JP2009209270A - Ink set, inkjet recording method using the same, and printed material - Google Patents

Abstract

An ink set capable of providing a printed matter having high scratch resistance and high print density is provided.
In an ink set including cyan ink, yellow ink, and magenta ink, a water-insoluble colorant particle contained in the yellow ink has a dispersion average particle diameter of 60 to 200 nm, and is at least one of inks different from the yellow ink. An ink set comprising a resin emulsion in which a water-insoluble colorant particle contained in one has a dispersion average particle diameter of 5 to 50 nm and a resin emulsion particle has a dispersion average particle diameter of 1 to 50 nm.
[Selection figure] None

Description

  The present invention relates to an ink set, an ink jet recording method using the ink set, and a printed matter.

  The ink jet recording method is capable of high-speed recording, has a high degree of freedom in drawing patterns, and has low noise during recording. Further, there are advantages that image recording is possible at low cost and color recording is easy. Therefore, it is rapidly spreading and further developing today. Conventionally, a dye ink in which a water-soluble dye is dissolved in an aqueous medium has been widely used as the recording liquid. However, since the dye ink is inferior in water resistance and weather resistance of the printed matter, a pigment ink capable of improving this has been studied.

In recent years, application of ink jet printing techniques has been studied in the fields of industrial and industrial printing such as letterpress, flat plate, gravure, and offset. However, in the inks used in these printing methods, since the solvent or solvent type used in the ink liquid is different, for example, colorants used in the fields of industrial and industrial printing such as letterpress, flat plate, gravure, offset, etc. In the colorant used in the ink jet system, the pigment type is different, and therefore the hue of the printed matter may be different.
In the industrial and industrial printing fields, the so-called “print sample” such as Japan Color has become a standard for printing colors, and various inks that reproduce hues close to this have been studied (for example, patents). Reference 6).
Furthermore, in the ink for inkjet recording, various studies have been made in order to improve the print density of the printed matter and expand the color reproduction range (see, for example, Patent Documents 1 and 3-5).
In addition, when the average particle size of the pigment particles contained in the ink is small, a clear image is easily obtained, but the scratch resistance and the image fixing property to the printed object after printing tend to deteriorate, and the concentration is uniform. An ink using emulsion particles having an average particle diameter of 50 nm or less in order to obtain a printed image is disclosed (for example, see Patent Document 2).
JP 2006-274020 A JP 2004-169008 A JP 2004-2715 A JP 2004-231692 A JP 2007-186697 A JP-A-10-219166

By the way, the hue in the printed matter is not only treated as a physical quantity, but is evaluated by a psychophysical quantity (how it is perceived). The wide color reproduction range measured and calculated by the optical measuring instrument does not necessarily coincide with the good texture of the printed matter actually printed in full color. In particular, in a water-based ink used in an ink jet recording method or the like, the yellow pigment type exhibiting a hue close to the above-mentioned “print sample” has a high coloring power, so that the color reproducibility of a single color or a secondary color or an intermediate color can be obtained. In some cases, it is difficult to achieve both the visual balance of the entire printed matter printed in full color.
On the other hand, in the field of industrial and industrial printing, there is a case where large-size photographic paper is handled as the speed increases, and even when printing in large quantities or under conditions such as storage and transportation, higher resistance is achieved. Abrasion is required.
SUMMARY OF THE INVENTION An object of the present invention is to provide an ink set that can provide a printed matter having excellent color reproducibility, color tone balance, and scratch resistance.
Another object of the present invention is to provide an ink jet recording method using an ink set that can provide a printed matter excellent in color reproducibility, color balance, and scratch resistance.
Furthermore, an object of the present invention is to provide a printed matter recorded using an ink set that can provide a printed matter excellent in color reproducibility, color balance, and scratch resistance.

<1> In an ink set containing cyan ink, yellow ink, and magenta ink, the water-insoluble colorant particles contained in the yellow ink have a dispersion average particle diameter of 60 to 200 nm, and are at least one ink different from the yellow ink. An ink set comprising a resin emulsion in which the water-insoluble colorant particles contained in the resin have a dispersion average particle diameter of 5 to 50 nm and the resin emulsion particles have a dispersion average particle diameter of 1 to 50 nm.
<2> The ink set according to <1>, wherein the water-insoluble colorant particles contained in at least one of the inks different from the yellow ink have a crystal structure.
<3> The polydispersity index (PDI) represented by the following formula (1) of water-insoluble colorant particles contained in at least one of the inks different from the yellow ink is <1> or < The ink set according to 2>.
Formula (1)
PDI = (D ₉₀ -D ₁₀ ) / D ₅₀
[In the formula, D ₉₀ , D ₅₀ , and D ₁₀ are integrals of the distribution function dG = F (D) dD (G is the number of pigment particles, D is the particle size), respectively, which is 0.9 of the total number of pigment particles. It represents a particle size equal to (90 number%), 0.5 (50 number%) and 0.1 (10 number%). ]
<4> At least one of the inks different from the yellow ink contains a dispersant, and the dispersant is one or more hydrophilic groups selected from a carboxylic acid group, a sulfone group, a phosphoric acid group, a hydroxyl group, and an ethylene oxide group. The ink set according to any one of the above items <1> to <3>, wherein the ink set is a compound having:
<5> The ink set according to any one of <1> to <4>, wherein the yellow ink includes a resin emulsion having a dispersion average particle diameter of 1 to 60 nm.
<6> Water-insoluble colorant particles contained in the yellow ink are C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 110, pigment yellow 138, C.I. I. Pigment yellow 151, and C.I. I. The ink set according to any one of <1> to <5>, wherein the ink set includes one or more pigments selected from CI Pigment Yellow 155.
<7> The water-insoluble colorant particles contained in the magenta ink are C.I. I. Pigment red 122, C.I. I. Pigment red 202, C.I. I. Pigment red 254, and C.I. I. The ink set according to any one of the above items <1> to <6>, comprising one or more pigments selected from pigment violet 19.
<8> The ink set according to any one of <1> to <7>, wherein the water-insoluble colorant particles contained in the cyan ink include a copper phthalocyanine pigment.
<9> An ink jet recording method using the ink set according to any one of <1> to <8>.
<10> A printed matter recorded using the ink set according to any one of <1> to <9>.

ADVANTAGE OF THE INVENTION According to this invention, the ink set which can provide the printed matter which is excellent in wide color reproducibility, color tone balance, and abrasion resistance can be provided.
Further, according to the present invention, it is possible to provide an ink jet recording method using an ink set that can provide a printed matter excellent in color reproducibility, color tone balance, and scratch resistance.
Furthermore, according to the present invention, it is possible to provide a printed matter having excellent scratch resistance, color reproducibility, and color balance recorded using an ink set.

The ink set according to the present invention includes at least three inks including yellow, magenta, and cyan inks.
In the ink set, the ink of each color includes a water-insoluble color material, and the average particle diameter of the water-insoluble color material particles in the ink of each color is in a specific range, thereby being excellent in abrasion resistance. The present inventors have found that it is possible to provide a printed material that can express a hue in a wide color reproduction range and has an excellent color balance when printed in full color.
Furthermore, it has been found that by selecting a specific water-insoluble color material, it is possible to provide a printed material having a hue close to “printed sample” or the like and capable of providing a higher definition.

  The present invention provides an ink set including cyan ink, yellow ink, and magenta ink, wherein the water-insoluble colorant particles contained in the yellow ink have a dispersion average particle size (volume) of 60 to 200 nm and are different from the yellow ink. The water-insoluble colorant particles contained in at least one of the above are characterized by containing a resin emulsion having a dispersion average particle size (volume) of 5 to 50 nm and a dispersion average particle size of 1 to 50 nm.

  That is, the water-insoluble colorant particles contained in the yellow ink and the water-insoluble colorant particles contained in at least one of the inks different from the yellow ink each have a dispersion average particle diameter in the above range, In a printed matter printed in full color, at least one of different inks contains a resin emulsion having a dispersion average particle diameter of 1 to 50 nm, and the color reproduction range that is measured and calculated using a color patch or the like is wide. It is possible to provide a printed matter which is visually excellent in color tone balance (color balance) and excellent in abrasion resistance.

  The reason for this is not clear, but by refining the water-insoluble colorant particles contained in the ink, the color reproduction range is expanded by increasing the transparency of the colorant, and the light scattering in the colorant particles is further increased. It is considered that the optical density in the ink and the printed material increases as the component decreases.

  On the other hand, the human eye has three types of photoreceptor cells sensitive to the wavelengths of red, green, and blue, and perceives color according to the degree of stimulation. Further, the visibility in the wavelength range of green to yellow-green is maximized by the number of these photoreceptor cells and the distribution of the spectral sensitivity range.

  On the other hand, in the printing field, a so-called “process color” called color ink including yellow, magenta, and cyan ink and ink set including black ink are mainly used. These colors are used to express various colors based on the principle of “subtractive color mixing”. Therefore, it is conceivable that the sensitivity of the hue expressed using yellow ink is high visually.

  In the present invention, by setting the dispersion average particle size (volume) of the water-insoluble colorant particles contained in the yellow ink to 60 to 200 nm, the yellow ink has a high optical density and a certain degree of concealment. As a result, when yellow ink is used together with other inks, a printed matter printed in full color while maintaining a wide color reproduction range has a smooth change in color tone and an excellent balance of the whole printed matter.

(Average particle size of water-insoluble colorant particles)
The average particle size of the water-insoluble colorant particles contained in the ink set of the present invention can be determined as follows.

[Dispersion average particle diameter by dynamic light scattering method (volume)]
The volume average particle diameter obtained by the following dynamic light scattering method is adopted as the dispersion average particle diameter of the water-insoluble colorant particles contained in the ink in the ink set of the present invention. This volume average particle diameter is obtained by measuring the ink diluted with water at a dilution ratio of 1 to 1000 times by Nikkiso Co., Ltd. (Microversion (Version 10.1.2-211BH)).
In the present invention, unless otherwise specified, the dispersion average particle diameter means a volume average particle diameter determined by a dynamic light scattering method.
In the present invention, the dispersion state of the water-insoluble colorant can be evaluated by determining the volume average particle diameter by the dynamic light scattering method. The principle is as follows.
Particles having a particle size in the range of about 1 nm to 5 μm change their position and orientation from moment to moment by Brownian motion such as translation and rotation in the liquid. Therefore, when these particles are irradiated with laser light and the scattered light emitted is detected, fluctuations in the scattered light intensity depending on the Brownian motion are observed. By observing the fluctuation of the scattered light intensity over time, the speed (diffusion coefficient) of the Brownian motion of the particles can be obtained, and further the size of the particles can be known.

  In the ink set of the present invention, when the resin emulsion is contained in each ink, the dynamic light scattering method described above is used to determine the volume average particle diameter of both the water-insoluble colorant particles and the resin emulsion particles contained in the ink. A value obtained by detecting is calculated. In such a case, the dispersion average particle diameter of the water-insoluble colorant particles in the ink is determined by using the transmission electron microscope observation (hereinafter referred to as TEM observation) described below and the dynamic light scattering method in combination. can do. Details are described below.

Using the dynamic light scattering method, the dispersion average particle size (volume) of the particles contained in the ink is measured, and the measured value is the average particle size (TEM average particle size) of the water-insoluble colorant obtained by TEM observation. ) Indicates that the water-insoluble colorant particles in the ink liquid are monodispersed (the particles are not joined or aggregated).
That is, in the dispersion medium, each particle is dispersed at a distance from each other and can move independently.
The case where the value of the dispersion average particle diameter (volume) by the dynamic light scattering method is close to the value of the TEM average particle diameter is specifically “dispersion average particle diameter (volume) calculated by the dynamic light scattering method. ”And“ TEM average particle size ”(dispersion average particle size (volume) calculated by dynamic light scattering method) /“ TEM average particle size ”) is 0.5 to 2.5. To tell.
From the viewpoint of the dispersion state, the value of “dispersion average particle diameter (volume) calculated by dynamic light scattering method” / “TEM average particle diameter” is more preferably 0.5 to 2.0, and dispersion In the medium, 0.5 to 1.5 is most preferable as a guideline that each particle is dispersed without being bonded or aggregated.

[Average particle diameter by TEM observation (TEM average particle diameter)]
In the present invention, the water-insoluble colorant particles contained in the ink can be calculated as follows by observing the shape of the particles by observation with a transmission electron microscope (TEM).
Ink containing fine particles of water-soluble coloring material is diluted in Cu200 mesh with a carbon film attached, dried and dried, and the diameter of 300 particles from an image taken with TEM (JEOL 1200EX) at a magnification of 100,000 times To obtain an average value.
At this time, since the ink is dried on the Cu 200 mesh as described above, even when the water-insoluble color material particles are well dispersed in the ink, the water-insoluble color material particles apparently appear during the drying process. Aggregation may occur, and it may be difficult to determine the exact particle size. In such a case, the average value is obtained by measuring the diameters of 300 independent particles that do not overlap. If the water-insoluble colorant is not spherical, the major axis of the particle (the longest diameter of the particle) is measured.

(Dispersion average particle size (volume) of water-insoluble color material contained in yellow ink)
In the present invention, the dispersion average particle size (volume) of the water-insoluble colorant particles contained in the yellow ink needs to be 60 to 200 nm.
In particular, when the dispersion average particle size (volume) of the water-insoluble colorant particles calculated by the dynamic light scattering method is 60 to 200 nm, the color reproducibility is excellent, and when it is 70 to 200 nm, both the coloring power and the hiding property are achieved. Therefore, it is more preferable. Furthermore, when it is 80 to 170 nm, the balance between coloring power and hiding properties is excellent, and in a printed matter printed in full color, the balance with other colors becomes good. Moreover, it is excellent also in light resistance. Furthermore, 80 to 130 nm is particularly preferable.
If the dispersion average particle size (volume) is too small, the transparency of the color material contained in the yellow ink is increased and the color reproducibility is excellent. However, since the coloring power becomes strong, a good balance with multiple colors cannot be maintained. There is a case. On the other hand, if it is too large, the hiding power of the color material increases, and a hue in a wide color reproduction range may not be obtained.

In this invention, it is preferable that the dispersion average particle diameter (volume) by the dynamic light scattering method performed with respect to the water-insoluble coloring material in a dispersion medium is close to the average particle diameter by the said TEM observation.
Specifically, the value of the dispersion average particle size (volume) by the dynamic light scattering method and the TEM average particle size are close to each other.
Ratio of “dispersion average particle diameter (volume)” calculated by dynamic light scattering method to “TEM average particle diameter” (“dispersion average particle diameter (volume) calculated by dynamic light scattering method) /“ TEM The average particle size ") is from 0.5 to 2.5.
Further, from the viewpoint of the dispersion state, it is more preferably 0.5 to 2.0, and 0.5 to 1.5 is the most preferable as a guideline that each particle is dispersed without being bonded or aggregated in the dispersion medium. This is the preferred case.

(Dispersion average particle diameter (volume) of water-insoluble color material contained in at least one of inks different from yellow ink)
In the present invention, the dispersion average particle size (volume) of the water-insoluble colorant contained in at least one kind of ink different from the yellow ink is 5 to 50 nm.
In particular, the dispersion average particle size (volume) of the water-insoluble colorant calculated by the dynamic light scattering method is more preferably 5 to 40 nm, and more preferably 5 to 30 nm from the viewpoint of enhancing transparency and coloring power. This is particularly preferable from the viewpoints of compatibility of ink transparency, dispersion stability in ink, and light resistance.
Within this range, it is possible to reproduce a hue of a wide color gamut and obtain a good color balance with multiple colors in a printed matter printed in full color. If the dispersion average particle size (volume) is too small, it may be difficult to maintain a stable dispersion state in the ink for a long period of time, and good light resistance may not be obtained. On the other hand, if it is too large, the transparency of the ink may not be obtained.

In the present invention, it is preferable that the dispersion average particle diameter (volume) by the dynamic light scattering method performed on the water-insoluble colorant in the dispersion medium is close to the average particle diameter by TEM observation.
The case where the value of the dispersion average particle diameter (volume) by the dynamic light scattering method is close to the value of the TEM average particle diameter is the same as that described in the section of the dispersion average particle diameter (volume) by the dynamic light scattering method. Meaning.

  In the present invention, water contained in yellow ink even when the primary particle size (TEM average particle size) of pigment particles contained in the water-insoluble colorant of the ink having a hue different from that of yellow ink is outside the above range. The dispersion average particle diameter of the insoluble colorant particles is in the range of 60 to 200 nm and the dispersion average particle diameter of the water-insoluble colorant particles contained in at least one ink of a hue different from that of the yellow ink is 5 to 200 nm. If it is 50 nm, it is the ink set of this invention.

  In the present invention, the primary particle size of the pigment particles contained in the water-insoluble colorant in the ink having a hue different from that of the yellow ink is preferably less than 50 nm, more preferably 10 to 45 nm, and further the colorant. From the viewpoint of enhancing the light resistance of the film, it is particularly preferably 15 to 45 nm.

In the present invention, at least one of the inks different from the yellow ink contains a dispersant, and the dispersant is selected from a carboxylic acid group, a sulfone group, a phosphoric acid group, a hydroxyl group, and an alkylene oxide (particularly, an ethylene oxide group). A compound having one or more hydrophilic groups is preferred. By containing the dispersant, the pigment can be favorably dispersed in an aqueous solvent.
Examples of the dispersant include dispersants (surfactants or polymer compounds) described in the later-described buildup pigment, and preferred examples are also the same.

(Definition of crystallite diameter)
In the ink set of the present invention, the water-insoluble colorant particles contained in each ink contain one or more pigments, but may be composed only of pigments or may contain compounds other than pigments. Moreover, the part which has a crystal structure and the part which does not have a crystal structure may be mixed in particle | grains. In addition, pigments and / or other compounds may form the core of the particles, and adsorb so as to be coated with a dispersant (polymer compound, surfactant, etc.) described later to form particles.
Further, “having a crystal structure” in this case means that none of the following (i) and (ii) is performed when a powder X-ray diffraction analysis is performed on a water-insoluble colorant contained in each ink.
(I) When amorphous halos are observed.
(Ii) When the crystallite diameter determined by the measurement method described below is estimated to be less than 20 mm or in an amorphous state.

In the present invention, the crystallite diameter is measured and calculated as follows.
First, X-ray diffraction analysis using Cu—Kα1 line is performed. Thereafter, in the range of 2θ = 4 deg to 70 deg, the half width of the peak showing the maximum intensity or the peak showing a sufficiently large intensity that can be separated from the adjacent peak is measured, and the crystallite diameter is calculated according to the following Serrer's formula. Calculate:
D = K × λ / (β × cos θ) ... Scherrer's formula
[D: crystallite size (Å, crystallite size), λ: measured X-ray wavelength (Å), β: broadening of diffraction lines depending on crystal size (radians), θ: Bragg angle of diffraction lines (radians) ), K: constant (different depending on β and D constants)]

In general, it is known that K = 0.9 when a half width β / 2 is used for β. Also, since the wavelength of the Cu-Kα1 line is 1.54050 mm, the crystallite diameter D in the present invention is calculated based on the following formula:
D = 0.9 × 1.54050 / (β / 2 × cos θ)

  Here, when the peak of the spectrum obtained by measurement is broad and the half width of the peak cannot be determined, the crystallite diameter is less than 20 mm (microcrystalline state) or is in an amorphous state (amorphous). It is estimated to be.

In the ink set of the present invention, in order to maintain high light resistance and obtain a hue of the same color gamut as that of the solid crystal, the water-insoluble colorant particles contained in at least one of the inks different from the yellow ink have a crystal structure. It is preferable to have. The crystallite size of the crystal forming this crystal structure has a crystallite size comparable to the dispersion average particle size (5 to 50 nm) of the water-insoluble colorant contained in at least one of the inks different from the yellow ink. Is particularly preferred.
When the average particle size calculated by TEM observation (or SEM observation, etc.) of water-insoluble colorant particles contained in at least one of the inks different from the yellow ink is smaller than the above-mentioned dispersion average particle size (5 to 50 nm) Preferably, the crystallite size has a crystallite size comparable to the TEM average particle size.
Here, the same degree is a maximum value within a range not exceeding the average particle diameter, and is, for example, about 40 mm of the particle diameter observed in principle in SEM observation. As a sample to be observed at this time, for example, a sample in which a dispersion of water-insoluble colorant particles is dropped onto a filter membrane having a pore diameter of about 0.05 μm to trap the water-insoluble colorant particles and then osmium-deposited.

  In the ink set of the present invention, the average particle diameter of the water-insoluble colorant particles contained in the magenta ink and the cyan ink is particularly preferably from the viewpoint of expanding the color reproduction range, and either the magenta ink or the cyan ink is preferable. If is within the above range, the effect of the present invention is achieved. More preferably, both magenta ink and cyan ink are within the above range.

In the water-based ink in the ink set of the present invention, since the pigment used for the magenta ink may have a weak coloring power, it is preferable that at least one of the inks different from the yellow ink is a magenta ink.
When the dispersion average particle diameter of the water-insoluble colorant contained in the magenta ink is within the above range (5 to 50 nm), the printed matter printed in full color has a hue density expressed using magenta ink. This is preferable because the color tone balance of the entire printed matter is improved. Moreover, since the transparency of the colorant is improved, a hue of a wide color gamut can be reproduced.

  Further, in the present invention, the dispersion density of the water-insoluble color material contained in the cyan ink is within the above range (5 to 50 nm). This is preferable because the color balance of the whole printed matter printed in full color is improved. In particular, since the color tone is improved from yellowish green to green, a printed matter having a visually good tone is obtained. Furthermore, since the transparency of the colorant is improved, a hue of a wide color gamut can be reproduced.

(Monodispersibility of water-insoluble colorant particles)
In the present invention, the dispersion average particle diameter of the water-insoluble colorant particles dispersed in the ink is preferably monodispersed. The term “monodispersed” here means that the distribution of the dispersion average particle diameter is narrow.
Since the water-insoluble colorant particles are monodispersed, the influence of light scattering and the like of the particles having a large particle diameter can be reduced. For example, the aggregates formed when forming aggregates by printing, recording, etc. using ink This is advantageous for controlling the filling mode.
As an index for evaluating the dispersibility of the ink, for example, in the number average particle diameter obtained by the dynamic light scattering method, the particle diameter distribution function of the particles dG = f (D) × dD (G is the number of particles, D is the primary particle diameter Represents
The difference between the particle size (D90) occupying 90% by number of the total number of particles and the particle size (D10) occupying 10% by number can be used.
In the present invention, the difference between D90 and D10 is preferably 45 nm or less, more preferably 1 to 30 nm, and particularly preferably 1 to 20 nm. This method can also be applied to a particle size distribution curve prepared using the particle size observed with the transmission electron microscope described above.

  Further, as an index for evaluating the dispersibility of the water-insoluble colorant particles of the present invention, there is a polydispersity index (PDI). The polydispersity index (PDI) is as defined below.

  The polydispersity index (PDI: polydispersity index) referred to in the present invention is an index that defines the particle size distribution of the ink, and is defined by the following formula (1).

Formula (1)
_{PDI = (D 90 -D 10)} / D 50
In the formula (1), D ₉₀ , D ₅₀ , and D ₁₀ are the integrals of the distribution function dG = F (D) dD, respectively, 0.9 (90% by number) and 0.5 (50 Particle size) equal to 0.1 (10 number%). G represents the number of water-insoluble colorant particles, and D represents the particle size of the water-insoluble colorant particles.

The relational expression (1) will be further described.
In a coordinate system in which the particle size (D) of water-insoluble colorant particles is plotted on the abscissa and the particle number function (G) of each particle of a given size is plotted on the ordinate, the water-insoluble colorant particle dispersion The curve of the distribution function of the particle size of the liquid is shown as a solid line. In addition, in the same coordinate system, create an integral of the distribution function in which the 10%, 50% and 90% particle number function points and the particle size related points D ₁₀ , D ₅₀ and D ₉₀ are represented by crosses.

  In the above relational expression, the narrower the particle size distribution is, the closer PDI is to zero. Conversely, the wider the particle size distribution, that is, the greater the polydispersity, the larger the PDI.

In the ink set of the present invention, the polydispersity index (PDI) of the water-insoluble colorant particles contained in at least one of the inks different from the yellow ink is preferably 2 or less, more preferably 0.2. It is -1.8, More preferably, it is 0.2-1.6.
The water-insoluble colorant particles of the ink different from the yellow ink have a dispersion average particle diameter of 5 to 50 nm and a polydispersity index (PDI) in the above range, whereby the transparency of the ink liquid is increased, and the printed matter. In this case, a high concentration tends to be obtained. If the polydispersity index (PDI) is outside the above range, the scattering component of the ink liquid tends to increase.

  This method can also be applied to a particle size distribution curve prepared using the particle size observed with the transmission electron microscope described above.

  Further, as another example of an index indicating dispersibility, a ratio (Mv / Mn) of volume average particle diameter (Mv) and number average particle diameter (Mn) obtained by a dynamic scattering method can be used. In the ink of the present invention, the Mv / Mn value is preferably 1.5 or less, more preferably 1.3 or less in order to reduce the scattering component of the color material, and 1.2 or less. Is particularly preferred.

  Furthermore, the above-described monodispersibility greatly contributes to the reduction of light scattering components in water-insoluble colorant particles in inks containing finely divided water-insoluble colorant particles having a dispersion average particle diameter of 5 to 50 nm. Therefore, it is particularly preferable that the ink containing finely divided water-insoluble colorant particles having a dispersion average particle diameter of 5 to 50 nm has monodispersibility within the above range.

In the ink set of the present invention, it is preferable that each ink contains few coarse particles or coarse secondary aggregates (indicating primary particle aggregates). Of the water-insoluble colorant particles contained in each ink, the number of water-insoluble colorant particles having a dispersion average particle diameter of 0.57 μm or more is 1.2 × 10 ⁷ particles / ml or less from the viewpoint of scratch resistance. Preferably, it is 1.0 × 10 ⁷ pieces / ml or less, and more preferably 0.8 × 10 ⁷ pieces / ml or less from the viewpoint of ejection stability.

  The number of water-insoluble colorant particles having a dispersion average particle size of 0.57 μm or more can be measured using a single particle optical detection method (SPOS). Specifically, an ACCUSIZER manufactured by PARTICLE SIZING SYSTEMS is used. Can be measured. As the measurement method, 0.5 ml of ink diluted to 5 ml with pure water is used, and the number of particles having a dispersion average particle diameter of 0.57 μm or more contained in the ink is measured at a measurement temperature of 25 ° C.

  In the present invention, the organic pigment constituting the water-insoluble colorant particles is not particularly limited in terms of hue or structure, for example, perylene compound pigment, perinone compound pigment, quinacridone compound pigment, quinacridone quinone compound pigment, anthraquinone compound pigment, Anthanthrone compound pigment, benzimidazolone compound pigment, disazo condensation compound pigment, disazo compound pigment, azo compound pigment, indanthrone compound pigment, indanthrene compound pigment, quinophthalone compound pigment, quinoxalinedione compound pigment, metal complex azo compound pigment, Phthalocyanine compound pigment, triarylcarbonium compound pigment, dioxazine compound pigment, aminoanthraquinone compound pigment, diketopyrrolopyrrole compound pigment, naphthol AS compound pigment, thioin Gore compound pigments, isoindoline compound pigments, isoindolinone compound pigments, pyranthrone compound pigments, isoviolanthrone compound pigment, or a mixture thereof.

  More specifically, examples of the organic pigment contained in the water-insoluble colorant contained in the yellow ink include C.I. l. Pigment Yellow 1 (Hansa Yellow), 2, 3 (Hansa Yellow 10G), 4, 5 (Hansa Yellow 5G), 6, 7, 10, 11, 12, 13, 14, 16, 17, 24 (Flavantron Yellow) , 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, 99, 108 (anthrapyrimidine yellow), 109, 110, 113, 117 ( (Copper complex pigment), 120, 124, 128, 129, 133 (quinophthalone), 138, 139 (isoindolinone), 147, 151, 153 (nickel complex pigment), 154, 155, 167, 172, 180, etc. be able to.

  Among these, from the viewpoint of use in water-based ink, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 110, pigment yellow 138, C.I. I. Pigment yellow 151, and C.I. I. Pigment Yellow 155 is preferable, and examples of the coloring material having a preferable hue and high coloring power include C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 74, pigment yellow 138, and C.I. I. Pigment Yellow 155 is more preferable, and C.I. having a high coloring power and a hue close to that of a color material used in offset printing or the like. I. Pigment Yellow 74 is most preferred.

  Examples of organic pigments for magenta ink include C.I. l. Pigment Red 1 (Para Red), 2, 3 (Toluidine Red), 4, 5 (lTR Red), 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21 22, 23, 30, 31, 32, 37, 38 (pyrazolone red), 40, 41, 42, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 88 (thioindigo), 112 (Naphthol AS series), 114 (Naphthol AS series), 122 (Dimethylquinacridone), 123, 144, 146, 149, 150, 166, 168 (Anthanthrone orange), 170 (Naphthol AS series), 171, 175, 176 , 177, 178, 179 (berylene maroon), 184, 185, 187, 202, 209 (dichloroquinacridone), 219, 224 Perylene-based), 245 (Naphthol AS yarn), 254, or, C. I. Pigment violet 19 (quinacridone), 23 (dioxazine violet), 32, 33, 36, 38, 43, 50, and the like.

  Among these, as a coloring material having a preferable hue and high coloring power, C.I. I. Pigment red 122, C.I. I. Pigment red 202, C.I. I. Pigment red 254, and C.I. I. C.I. Pigment Violet 19 is preferable, and has a high coloring power and a hue close to that of a color material used in offset printing or the like. I. Pigment red 122, or C.I. I. Pigment violet 19 is most preferred.

  Further, as organic pigments for cyan ink, C.I. l. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15:34, 15: 4, 16 (metal-free phthalocyanine), 18 (alkali blue toner), 22, 25, 60 ( Slen Blue), 65 (Biolantron), 66 (Indigo), C.I. l. Vat blue 4, 60 etc. can be mentioned.

  Among these, a copper phthalocyanine pigment is preferable as a colorant having a preferable hue and high coloring power. l. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15:34, and 15: 4 are more preferable, and have a high coloring power and a hue close to a color material used in offset printing or the like. Having C. I. Pigment blue 15: 3, or C.I. I. Pigment Blue 15: 4 is most preferred.

  The ink set of the present invention preferably further contains black ink.

As an inorganic pigment used for black, the following carbon black, for example, No. manufactured by Mitsubishi Chemical Corporation is used. 2300, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, or No2200B, etc .; Columbia-made Raven5750, Raven5250, Raven5000, Raven3500, Raven1255, Raven700, etc .; 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc .; or Color from Degussa
Black FW1, Color Black FW2, Color Black FW2V, Color Black FW18, Color Black
FW200, Color Black S150, Color Black S160, Color Black S170, Printex 35, Printex U, Printex V, Printex 140U, Special Black 6, A Special Black 5S
Further, as the organic pigment for black, a black organic pigment such as aniline black (C.I. Pigment Black 1) can be used.

Furthermore, as organic pigments used for color inks other than magenta, cyan or yellow inks, C.I. I. Pigment green 7 (phthalocyanine green), 10 (green gold), 36, 37;
C. I. Pigment Brown 3, 5, 25, 26; or
C. I. Pigment Orange 1, 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43, 63, etc. can be used.

  In the ink set according to the present invention, the color materials described above can be used alone or in combination of two or more. Moreover, in order to obtain a preferable hue, the solid solution pigment which consists of 2 or more types of coloring materials mentioned above may be included.

The ink in the ink set of the present invention contains the water-insoluble colorant particles, and the water-insoluble colorant is preferably a water-dispersible pigment. The pigment is as described above. Moreover, what is necessary is just to have the function to form an image by coloring, and dye and colored fine particles can also be used.
Specific examples of the water-dispersible pigment include the following pigments (1) to (5).
(1) An encapsulated pigment, that is, a polymer emulsion in which a pigment is contained in fine polymer particles. More specifically, the pigment is coated with a hydrophilic water-insoluble resin and is made hydrophilic by a resin layer on the surface of the pigment. A pigment is dispersed in water.
(2) Self-dispersing pigments, that is, pigments having at least one hydrophilic group on the surface and exhibiting at least one of water dispersibility and water solubility in the absence of a dispersant, more specifically, mainly carbon black Etc. are hydrophilized by surface oxidation treatment so that the pigment alone is dispersed in water.
(3) A resin-dispersed pigment, that is, a pigment dispersed with a water-soluble polymer compound having a mass average molecular weight of 50,000 or less. (4) A surfactant-dispersed pigment, that is, a pigment dispersed with a surfactant.
(5) An organic pigment and a polymer dispersant, or a polymer compound as a dispersant is dissolved in an aprotic organic solvent in the presence of an alkali, and then this solution and water are mixed to prepare a pigment dispersion. Dispersed pigment prepared by the method (hereinafter, the dispersed pigment prepared by the above method is referred to as “build-up pigment”).
In the present invention, preferable examples of the pigment include (1) encapsulated pigment, (2) self-dispersing pigment, and (5) build-up pigment. Particularly preferable examples include (1) encapsulated pigment and ( 5) Build-up pigments can be mentioned.
Furthermore, when obtaining a dispersion of water-insoluble colorant particles having a dispersion average particle diameter of 5 to 50 nm, it is preferable to use (5) a build-up pigment.
(5) When a build-up pigment is used, particles having a fine particle diameter and monodispersed are obtained, and further, the above-described coarse particles or coarse secondary aggregates (showing aggregates of primary particles). Is preferable in that a pigment dispersion can be obtained. Moreover, although a reason is not certain, said (5) is preferable also at the point which is excellent in light resistance compared with said (1)-(4).

The microencapsulated pigment will be described in detail. The resin of the microencapsulated pigment is not limited, but is a high molecular compound having self-dispersibility or solubility in a mixed solvent of water and water-soluble organic and having an anionic group (acidic group) Is preferred.
This resin preferably has a number average molecular weight in the range of about 1,000 to 100,000, particularly preferably in the range of about 3,000 to 50,000, from the viewpoint of finer pigment particles and dispersion stability. . Further, it is preferable that this resin is dissolved in an organic solvent to form a solution.
When the number average molecular weight of the resin is within this range, the function as a coating film in the pigment or as a coating film in the ink can be sufficiently exhibited. The resin is preferably used in the form of an alkali metal or organic amine salt.

Specific examples of the resin for the microencapsulated pigment include thermoplastic, thermosetting or modified acrylic, epoxy, polyurethane, polyether, polyamide, unsaturated polyester, phenol, silicone, and fluorine. Polymer compounds, polyvinyl chloride, vinyl acetate, polyvinyl alcohol, polyvinyl butyral, etc., polyesters such as alkyd resin, phthalic acid resin, melamine resin, melamine formaldehyde resin, aminoalkyd cocondensation resin, urea resin, urea resin, etc. And materials having an anionic group such as a copolymer or a mixture thereof.
Among the above resins, anionic acrylic resins include, for example, acrylic monomers having an anionic group (hereinafter referred to as anionic group-containing acrylic monomers), and other monomers that can be copolymerized with these monomers as necessary. Is obtained by polymerization in a solvent.
Examples of the anionic group-containing acrylic monomer include an acrylic monomer having one or more anionic groups selected from the group consisting of a carboxyl group, a sulfonic acid group, and a phosphonic group. Among these, an acrylic monomer having a carboxyl group Is particularly preferred.

  Specific examples of the acrylic monomer having a carboxyl group include acrylic acid, methacrylic acid, crotonic acid, ethacrylic acid, propylacrylic acid, isopropylacrylic acid, itaconic acid, fumaric acid and the like. Among these, acrylic acid or methacrylic acid is preferable.

  The microencapsulated pigment can be produced by the conventional physical and chemical methods using the components described above. In the present invention, preferably, in JP-A-9-151342, JP-A-10-140065, JP-A-11-209672, JP-A-11-172180, JP-A-10-25440, or JP-A-11-43636. Manufacturing by the disclosed method is mentioned.

In the present invention, self-dispersing pigments can also be mentioned as preferred examples. A self-dispersing pigment refers to a number of hydrophilic functional groups and / or salts thereof (hereinafter referred to as dispersibility-imparting groups) directly or indirectly via an alkyl group, an alkyl ether group, an aryl group, or the like on the pigment surface. Are pigments that are bonded together and dispersible in an aqueous medium without a dispersant.
Here, “dispersible in an aqueous medium without a dispersant” means that the pigment can be dispersed in an aqueous medium without using a dispersant for dispersing the pigment.
Inks containing a self-dispersing pigment as a colorant do not need to contain a dispersant as described above that is contained in order to disperse a normal pigment. It is easy to prepare ink that is excellent in ejection stability.
Examples of dispersibility-imparting groups to be bonded to the surface of the self-dispersion _{pigment, -COOH, -CO, -OH, -SO} 3 H, -PO 3 H 2 and quaternary ammonium and salts thereof can be exemplified.
Self-dispersing pigments containing these dispersibility-imparting groups or active species having a dispersibility-imparting group can be obtained by subjecting the pigment as a raw material to a physical treatment or a chemical treatment, thereby providing a dispersibility-imparting group or a dispersibility-imparting group. It is produced by bonding (grafting) the active species having to the surface of the pigment.
Examples of the physical treatment include vacuum plasma treatment. Examples of the chemical treatment include a wet oxidation method in which the pigment surface is oxidized with an oxidizing agent in water, and a method in which a carboxyl group is bonded via a phenyl group by bonding p-aminobenzoic acid to the pigment surface. It can be illustrated.
In the present invention, preferred examples include self-dispersing pigments that are surface-treated by oxidation treatment with hypohalous acid and / or hypohalite or oxidation treatment with ozone.
Commercially available products can also be used as the self-dispersing pigment, such as Microjet CW-1 (trade name; manufactured by Orient Chemical Co., Ltd.), CAB-O-JET200, CAB-O-JET300 (above products) Name; manufactured by Cabot Corporation).

In the present invention, examples of the dispersant used in the (1) encapsulated pigment or (3) resin-dispersed pigment include nonionic compounds, anionic compounds, cationic compounds, and amphoteric compounds.
Examples thereof include a copolymer of monomers having an α, β-ethylenically unsaturated group. Examples of monomers having an α, β-ethylenically unsaturated group include ethylene, propylene, butene, pentene, hexene, vinyl acetate, allyl acetate, acrylic acid, methacrylic acid, crotonic acid, crotonic acid ester, itaconic acid, itacone Acid monoester, maleic acid, maleic acid monoester, maleic acid diester, fumaric acid, fumaric acid monoester, vinyl sulfonic acid, styrene sulfonic acid, sulfonated vinyl naphthalene, vinyl alcohol, acrylamide, methacryloxyethyl phosphate, bismethacryloxy Styrene derivatives such as ethyl phosphate, methacryloxyethyl phenyl acid phosphate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, styrene, α-methylstyrene, vinyltoluene , Vinylcyclohexane, vinylnaphthalene, vinylnaphthalene derivatives, alkyl acrylates that may be substituted with aromatic groups, phenyl esters of acrylate, alkyl methacrylates that may be substituted with aromatic groups, phenyl esters of methacrylic acid, methacryl Acid cycloalkyl ester, crotonic acid alkyl ester, itaconic acid dialkyl ester, maleic acid dialkyl ester, vinyl alcohol, and derivatives of the above compounds.

A copolymer obtained by copolymerizing one or more monomers having the α, β-ethylenically unsaturated group is used as a polymer dispersant. Specifically, acrylic acid alkyl ester-acrylic acid copolymer, methacrylic acid alkyl ester-methacrylic acid copolymer, styrene-alkyl acrylic acid ester-acrylic acid copolymer, styrene-methacrylic acid phenyl ester-methacrylic acid, Styrene-methacrylic acid cyclohexyl ester-methacrylic acid copolymer, styrene-styrenesulfonic acid copolymer, styrene-maleic acid copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid copolymer, vinylnaphthalene-maleic Examples include acid copolymers, vinyl naphthalene-methacrylic acid copolymers, vinyl naphthalene-acrylic acid copolymers, polystyrene, polyester, and polyvinyl alcohol.
The dispersant preferably has a weight average molecular weight of 2,000 to 60,000.
In addition, the ratio of the dispersant added to the pigment is preferably from 10% to 100%, more preferably from 20% to 70%, and still more preferably from the viewpoint of pigment dispersion stability. 40% or more and 50% or less.

Subsequently, the build-up pigment will be described in detail.
The build-up pigment can be produced in a solid or dispersed form by the following steps (1) to (3) and further including steps (4) and (5).

The build-up pigment in the present invention is preferably
(1) a step of preparing a solution in which a water-insoluble colorant (organic pigment) and a dispersant are dissolved in an aprotic water-soluble organic solvent in the presence of an alkali;
(2) A step of mixing the solution and an aqueous medium to obtain a dispersion in which the water-insoluble colorant particles and the dispersing agent are dispersed in a medium containing water;
(3) a step of forming a soft aggregate obtained by agglomerating particles of the water-insoluble colorant so as to be redispersible, and separating the soft aggregate from the dispersion;
(4) A step of filtering and washing the soft aggregate with an ester solvent or a ketone solvent,
(5) The soft agglomerates can be produced by a process of releasing the aggregation and redispersing in the redispersion medium.

  As the aprotic solvent used in the present invention, any solvent capable of dissolving the organic pigment and the polymer compound in the presence of an alkali can be used. Further, those having a solubility in water of 5% by mass or more are preferably used, and those that are freely mixed in water are preferred.

Specifically, dimethyl sulfoxide, dimethyl imidazolidinone, sulfolane, N-methylpyrrolidone, dimethylformamide, acetonitrile, acetone, dioxane, tetramethylurea, hexamethylphosphoramide, hexamethylphosphorotriamide, pyridine, propionitrile , Butanone, cyclohexanone, tetrahydrofuran, tetrahydropyran, ethylene glycol diacetate, γ-butyrolactone, etc. are mentioned as preferred solvents, among which dimethylsulfoxide, N-methylpyrrolidone, dimethylformamide, dimethylimidazolidinone, sulfolane, acetone or acetonitrile, tetrahydrofuran Is preferred. Moreover, these can be used individually by 1 type or in combination of 2 or more types.
The proportion of the aprotic solvent used is not particularly limited, but in order to make the pigment in a better dissolved state, the ease of forming the desired fine particle diameter, and the color density of the aqueous dispersion better. The pigment is preferably used in an amount of 2 to 500 parts by mass, and further 5 to 100 parts by mass with respect to 1 part by mass of the pigment.

  As the alkali contained in the aprotic solvent, an inorganic base such as sodium hydroxide, calcium hydroxide or barium hydroxide, or an organic base such as trialkylamine, diazabicycloundecene (DBU) or metal alkoxide is used. Among them, it is preferable to use an inorganic base. The amount of alkali to be contained is not particularly limited, but in the case of an inorganic base, it is preferably 1.0 to 30 molar equivalents, more preferably 2.0 to 25 molar equivalents, and 3 to 20 relative to the pigment. A molar equivalent is particularly preferred. In the case of an organic base, it is preferably 1.0 to 100 molar equivalents, more preferably 5.0 to 100 molar equivalents, and particularly preferably 20 to 100 molar equivalents with respect to the pigment.

  In the present invention, the aqueous solvent is water alone or a mixed solvent of water-soluble organic solvents. At this time, the addition of the organic solvent is not sufficient only with water to uniformly dissolve the pigment and the dispersant, and when only water is insufficient to obtain the viscosity necessary to flow through the flow path. It is preferable to use for such as. For example, in the case of alkali, the organic solvent is preferably an amide solvent or a sulfur-containing solvent, more preferably a sulfur-containing solvent, and particularly preferably dimethyl sulfoxide (DMSO). In the case of acidity, a carboxylic acid solvent, a sulfur solvent, or a sulfonic acid solvent is preferable, a sulfonic acid solvent is more preferable, and methanesulfonic acid is particularly preferable. In addition, you may dissolve an inorganic compound salt, the dispersing agent mentioned later, etc. in an aqueous solvent as needed.

  At this time, the embodiment in which the solution in which the water-insoluble colorant is uniformly dissolved and the aqueous solvent are mixed is not particularly limited. For example, an embodiment in which a water-based solvent is stirred and a solution of a water-insoluble coloring material is added thereto, and the solution and the water-based solvent are respectively sent to a long flow path in the same longitudinal direction and pass through the flow path. An embodiment in which both liquids are brought into contact with each other during the process to deposit organic pigment fine particles is exemplified. The former (embodiment for stirring and mixing) is particularly preferably an embodiment by adding in a liquid in which a supply pipe or the like is introduced into an aqueous solvent and a solution of a water-insoluble colorant is added therefrom. More specifically, addition in liquid can be performed using the apparatus described in paragraphs 0036 to 0047 of the pamphlet of International Publication No. WO2006 / 121018. As for the latter (embodiment in which both are mixed using a flow path), for example, paragraphs 0049 to 52 of Japanese Patent Application Laid-Open No. 2005-307154 and FIGS. 1 to 4 and paragraphs 0044 to 0050 of Japanese Patent Application No. 2006-78637. Can be used.

  There are no particular restrictions on the conditions for precipitation of water-insoluble colorant particles, and a range from normal pressure to subcritical and supercritical conditions can be selected. The temperature at normal pressure is preferably −30 to 100 ° C., more preferably −10 to 60 ° C., and particularly preferably 0 to 30 ° C. The mixing ratio of the water-insoluble colorant solution and the aqueous solvent is preferably 1/50 to 2/3, more preferably 1/40 to 1/2, and particularly preferably 1/20 to 3/8 in volume ratio. The particle concentration in the mixed solution when the particles are precipitated is not particularly limited, but the water-insoluble colorant particles are preferably in the range of 10 to 40,000 mg, more preferably in the range of 20 to 30000 mg with respect to 1000 ml of the solvent. And particularly preferably in the range of 50 to 25000 mg.

In the preparation of the build-up pigment, the dispersant is soluble in an aprotic organic solvent in the presence of an alkali, and when a water-insoluble colorant, a solution in which the dispersant is dissolved, and an aqueous solvent are mixed, What can obtain a dispersion effect by forming pigment content particles in an aqueous solvent can be used suitably.
Preferably, it is a surfactant or a polymer compound, and the hydrophilic part thereof is one or more of carboxylic acid group, sulfonic acid group, phosphoric acid group, hydroxyl group and alkylene oxide (particularly ethylene oxide). What is configured is used.
More preferably, those which can be stably dissolved together with an organic pigment in an aprotic organic solvent in the presence of an alkali. An aqueous dispersion of an organic pigment containing an alkali when the hydrophilic part of the dispersant is composed only of those selected from the above, such as primary, secondary, tertiary amino groups, quaternary ammonium groups, etc. Although sufficient in the body, the degree of dispersion stabilization may be relatively low.
Further, in the conventional pigment dispersion method, it is necessary to devise a method such as selecting a dispersant that can efficiently contact the pigment surface in a dispersed state in the medium. However, in the present invention, both the dispersant and the pigment are dissolved. In the state in the medium, the desired action between them can be easily obtained, so there is no limitation on the dispersant based on the contact efficiency with the pigment surface as in the conventional pigment dispersion method, and a wide range A dispersant can be used.

  Specific examples of surfactants include alkylbenzene sulfonates, alkyl naphthalene sulfonates, higher fatty acid salts, higher fatty acid ester sulfonates, higher alcohol ether sulfates, higher alcohol ether sulfonates, higher Anionic surfactants such as alkyl carboxylates and alkyl phosphates of alkyl sulfonamides, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, ethylene oxide adducts of acetylene glycol , Nonionic surfactants such as ethylene oxide adducts of glycerin and polyoxyethylene sorbitan fatty acid esters, and other amphoteric boundaries such as alkylbetaines and amide betaines Active agents, silicone surface active agents, including such fluorine-based surfactant, can be appropriately selected from surfactants and derivatives thereof are known.

  Specific examples of the polymer dispersant include polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl methyl ether, polyethylene oxide, polyethylene glycol, polypropylene glycol, and polyacrylamide. Among them, polyvinyl pyrrolidone is preferably used.

  Other polymer compounds used as dispersants include styrene, styrene derivatives, vinyl naphthalene, vinyl naphthalene derivatives, aliphatic alcohol esters of α, β-ethylenically unsaturated carboxylic acids, acrylic acid, acrylic acid derivatives, methacrylic acid. Acid, methacrylic acid derivative, maleic acid, maleic acid derivative, alkenyl sulfonic acid, vinylamine, allylamine, itaconic acid, itaconic acid derivative, fumaric acid, fumaric acid derivative, vinyl acetate, vinylphosphonic acid, vinylpyrrolidone, acrylamide, N-vinyl At least two or more monomers selected from acetamide, N-vinylformamide, and derivatives thereof (of which at least one is any one of a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a hydroxyl group, and an alkylene oxide) Functional group A block copolymer composed of monomers), a random copolymer, a graft copolymer, a modified product thereof, a salt thereof, and the like.

  More specifically, the polymer compound in the present invention is preferably composed of a hydrophilic group site and a hydrophobic site, and a copolymer obtained by copolymerizing a hydrophilic monomer component and a hydrophobic monomer component is used. Is preferred. When using a polymer compound which is a polymer composed only of a hydrophobic monomer component, it may be difficult to impart good dispersion stability to the water-insoluble colorant. The hydrophilicity is a property that has a high affinity for water and is easily dissolved in water, and the hydrophobic property is a property that has a low affinity for water and is difficult to dissolve in water.

  For example, as a hydrophobic monomer component, a monomer component having a hydrophobic unit such as an isobutyl group, a t-butyl group, a phenyl group, a biphenyl group, or a naphthyl group as a structural unit can be mentioned. From the viewpoint of imparting high dispersion stability to the water-insoluble colorant, a block segment having a hydrophobic monomer such as styrene or t-butyl methacrylate as a repeating unit is preferable, but the hydrophobic monomer component is not limited thereto.

  Examples of the hydrophilic monomer component include monomer components containing a hydrophilic unit such as a structure having a functional group such as a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a hydroxyl group, and an alkylene oxide as a unit structure. . Among these, from the viewpoint of improving dispersion stability due to the charge repulsion effect between water-insoluble colorant particles, it is preferable to have a carboxylic acid group, a sulfonic acid group, and a phosphoric acid group as a unit structure, and the long-term stability of the dispersion, and From the viewpoint of improving image fixability when used as an ink, it is particularly preferable to have a carboxylic acid group as a unit structure. Specific examples include acrylic acid and methacrylic acid, or carboxylates such as inorganic salts and organic salts thereof, polyethylene glycol macromonomer, vinyl alcohol, 2-hydroxyethyl methacrylate, and the like. It is not limited to this.

  The copolymer may be a block copolymer or a copolymer having any form such as a random copolymer or a graft copolymer, but particularly when a block copolymer or a graft copolymer is used. The water-insoluble colorant is preferred because it easily imparts good dispersibility.

Moreover, as a high molecular compound used as another dispersing agent, natural high molecular compounds such as albumin, gelatin, rosin, shellac, starch, gum arabic, and sodium alginate, and modified products thereof can be preferably used. Moreover, these dispersing agents can be used individually by 1 type or in combination of 2 or more types.
The proportion of the dispersant used is not particularly limited, but 0.05 parts by mass or more with respect to 1 part by mass of a water-insoluble colorant (particularly, an organic pigment) and 100 parts by mass of an aprotic organic solvent. It is preferable to use in the range of 50 parts by mass or less.
When the dispersant is more than 50 parts by mass with respect to 100 parts by mass of the aprotic organic solvent, it may be difficult to completely dissolve the dispersant, and from 0.05 part by mass with respect to 1 part by mass of the organic pigment. If the amount is small, it may be difficult to obtain a sufficient dispersion effect.

In the ink of the present invention, the above-described dispersant can be preferably used when considering improvement in weather resistance, but the weather resistance is improved and low viscosity is maintained even when the concentration of the dispersion is increased. In view of the above, it is particularly preferable to use a polymer dispersant or a polymer compound that is soluble or dispersible in a specific organic solvent used in the washing treatment described later.
The molecular weight of the polymer dispersant or polymer compound is not particularly limited, but the weight average molecular weight is preferably 500 to 1,000,000, and more preferably 1,000 to 1,000,000. When the molecular weight is less than 500, the molecular weight is small, and when it exceeds 1,000,000, the entanglement between the polymer chains becomes too large and the function as a dispersant becomes difficult to be exhibited.
In the present invention, the term “molecular weight” means a weight average molecular weight, and the weight average molecular weight is an average molecular weight in terms of polystyrene measured by gel permeation chromatography (carrier: tetrahydrofuran) unless otherwise specified.
In the present invention, the “dispersion” refers to a composition in which predetermined fine particles are dispersed, and the form thereof is not particularly limited, and is a liquid composition (dispersion), a paste-like composition, and a solid composition. Used to mean including things.

  The amount of the dispersant contained in the solution in which the water-insoluble colorant is dissolved is 0.1 to 1000 parts by mass with respect to 100 parts by mass of the pigment in order to further improve the uniform dispersibility and storage stability of the pigment. Is preferable, it is more preferable that it is the range of 1-500 mass parts, and it is especially preferable that it is the range of 10-250 mass parts. If this amount is too small, the dispersion stability of the organic pigment fine particles may not be improved. The amount of the dispersant contained in the dispersion of the present invention is not particularly limited, but is practically 10 to 1000 parts by mass with respect to 100 parts by mass of the pigment.

In the dispersion, as described in detail below, the mixed solution in which the particles of the water-insoluble colorant are precipitated is acid-treated, and preferably, an acid is added to the formation of the agglomerates, and the particles are aggregated. It is preferable to form an aggregate.
The treatment using an acid preferably includes a step of aggregating the particles with an acid, separating the particles from a solvent (dispersion medium), and performing concentration, desolvation, and desalting (deoxidation). By making the system acidic, the electrostatic repulsion force due to the acidic hydrophilic portion can be reduced and the particles can be aggregated.

As the acid used here, it is usual to agglomerate fine particles that are difficult to precipitate into a slurry, paste, powder, granule, cake (lumb), sheet, short fiber, flake, etc. Any material can be used as long as it can be efficiently separated from the solvent by a separation method.
More preferably, an acid that forms a water-soluble salt with an alkali should be used, and the acid itself is preferably highly soluble in water. In order to efficiently perform desalting, the amount of acid to be added is preferably as small as possible within the range in which the particles aggregate.
Specific examples include hydrochloric acid, sulfuric acid, nitric acid, acetic acid, phosphoric acid, trifluoroacetic acid, dichloroacetic acid, methanesulfonic acid and the like, with hydrochloric acid, acetic acid and sulfuric acid being particularly preferred. An aqueous dispersion of pigment particles that can be easily separated by an acid can be easily separated by a centrifugal separator, a filtration device, or a slurry solid-liquid separation device. At this time, the degree of desalting and solvent removal can be adjusted by adding dilution water or increasing the number of decantations and washings.

  The agglomerates obtained here can be used as a paste or slurry having a high water content, but if necessary, drying such as spray drying, centrifugal drying, filtration drying or freeze drying may be used. Depending on the method, it can also be used as fine powder.

In the aqueous dispersion, the water-insoluble colorant has a crystal structure. In order to form this crystal structure, it is preferable to contact the soft aggregate of the particles with an organic solvent.
As this organic solvent, an ester solvent, a ketone solvent, an alcohol solvent, an aromatic solvent, and an aliphatic solvent are preferable, an ester solvent and a ketone solvent are more preferable, and an ester solvent is particularly preferable.

  Examples of the ester solvent include ethyl acetate, ethyl lactate, 2- (1-methoxy) propyl acetate and the like. Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples of the alcohol solvent include methanol, ethanol, n-butanol and the like. Examples of the aromatic solvent include benzene, toluene, xylene and the like. Examples of the aliphatic solvent include n-hexane and cyclohexane. Ethyl acetate, acetone, and ethyl lactate are preferable, and acetone and ethyl lactate are particularly preferable.

  Although the usage-amount of the said organic solvent is not specifically limited, For example, it is preferable to use 0.01-10000 mass parts with respect to 100 mass parts of pigments. The amount of the organic solvent contained in the aqueous dispersion of the present invention is not particularly limited, but is practically 0.0001 to 1% by mass.

  The method of bringing the obtained aggregate into contact with the organic solvent is not particularly limited, but a method capable of separating the aggregate and the organic solvent after contacting is preferable. In addition, a method in which the organic solvent can be separated in a liquid state at the time of separation is preferable, and for example, filter filtration is preferable.

Although the reason is not clear, the crystallite size can be increased without increasing the particle size of the water-insoluble colorant particles contained in the dispersion by performing the contact treatment with the organic solvent.
That is, the crystallinity of the water-insoluble colorant particles can be increased while maintaining the primary particle size at the time of precipitation of the particles. Furthermore, in the redispersion treatment described later, it is possible to redisperse in water or the like while maintaining the primary particle size at the time of precipitation of particles, and high dispersion stability is also maintained. Further, by performing the above treatment, a low viscosity can be maintained even when the concentration of the aggregate redispersion is increased. Furthermore, when used as an ink jet recording liquid, it has good ejection properties.
These effects are presumed to have occurred because the dispersion was brought into contact with the organic solvent and then separated to release and remove the excess dispersant contained in the dispersion.

  At this time, since the dispersant near the surface of the water-insoluble colorant particles in the dispersion is strongly fixed to the water-insoluble colorant particles, the particle size of the water-insoluble colorant particles does not increase, which will be described later. Even after the redispersion treatment, high dispersion stability is maintained while maintaining the primary particle size at the time of precipitation of the particles.

In the dispersion, it is preferable to redisperse the aggregate. Examples of the redispersion treatment include alkali treatment.
That is, it is preferable to neutralize particles aggregated using an acid with an alkali and re-disperse them in water or the like with a primary particle size at the time of precipitation. Since desalting and solvent removal have already been performed, a concentrated base with few impurities can be obtained.
The alkali used here functions as a neutralizing agent for the dispersant having an acidic hydrophilic portion, and increases the solubility in water. Any alkali can be used.
Specifically, various organic amines such as aminomethylpropanol, dimethylaminopropanol, dimethylethanolamine, diethyltriamine, monoethanolamine, diethanolamine, triethanolamine, butyldiethanolamine, morpholine, sodium hydroxide, lithium hydroxide, potassium hydroxide And alkali metal hydroxides such as ammonia. These 1 type (s) or 2 or more types can be used in combination.

  The amount of the alkali used is not particularly limited as long as the aggregated particles can be stably redispersed in water, but when used for applications such as printing ink and ink jet printer ink, corrosion of various members. Therefore, it is preferable to use an amount that makes the pH 6 to 12, more preferably 7 to 11.

In addition, a method different from the alkali treatment may be used depending on the dispersant used at the time of particle precipitation.
For example, the redispersion treatment using the low molecular dispersant or polymer dispersion described above can be mentioned. In this case, a conventionally known dispersion treatment means may be used. For example, a disperser such as a sand mill, a bead mill, a ball mill, or a dissolver, or an ultrasonic treatment may be used. These redispersion treatments may be used in combination with the alkali treatment described above.

Further, when re-dispersing the aggregated particles, a water-soluble organic solvent can be added as a re-dispersing medium to facilitate re-dispersion.
Specific examples of organic solvents that can be used include, but are not limited to, lower alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and tert-butanol, acetone, methyl ethyl ketone, and methyl isobutyl ketone. , Aliphatic ketones such as diacetone alcohol, ethylene glycol, diethylene glycol, triethylene glycol, glycerin, propylene glycol, ethylene glycol monomethyl or monoethyl ether, propylene glycol methyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, ethylene Glycol phenyl ether, propylene glycol phenyl ether, diethylene glycol monomethyl or Bruno ethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl or monoethyl ether, N- methylpyrrolidone, 2-pyrrolidone, dimethylformamide, dimethylimidazolidinone, dimethyl sulfoxide, dimethyl acetamide and the like. These can be used alone or in combination of two or more.
Further, when the pigment particles are redispersed to obtain an aqueous dispersion, the amount of water here is preferably 99 to 20% by mass, and more preferably 95 to 30% by mass. The amount of the water-soluble organic solvent is preferably 50 to 0.1% by mass, and more preferably 30 to 0.05% by mass.

When adding water, the said alkali, and a water-soluble organic solvent to the aggregated particle | grains, stirring, mixing, and a dispersion device can be used as needed. In particular, when using a paste or slurry of an organic pigment having a high water content, it is not necessary to add water.
Furthermore, heating, cooling, distillation or the like can be performed for the purpose of increasing the efficiency of redispersion and for removing unnecessary water-soluble organic solvents or excess alkali.

The ink in the present invention can be prepared by using the dispersion and mixing, for example, each component such as a polymer compound, a surfactant, and an aqueous solvent, and dissolving or dispersing uniformly.
The ink according to the present invention preferably contains 0.1 to 15% by mass of the water-insoluble colorant.
Further, when an excessive amount of a polymer compound or additive is contained in the prepared ink, the ink can be re-prepared by appropriately removing them by a method such as centrifugation or dialysis.

(Resin emulsion)
In the ink set of the present invention, at least one of the inks different from the yellow ink includes water-insoluble colorant particles having a dispersion average particle diameter of 5 to 50 nm, and the dispersion particle diameter of the resin emulsion particles is 1 to 50 nm. A resin emulsion.
By adding the resin emulsion to at least one ink different from the yellow ink, the obtained printed matter is prevented from irregular reflection of the pigment particles in the print image portion, and becomes a print image having a uniform density, In addition, the abrasion resistance of the printed portion is improved. The resin emulsion in the present invention refers to resin emulsion particles (also referred to as “emulsion particles”) in which the continuous phase is water and the dispersed phase is a component described later.

Dispersed phase components include acrylic, vinyl acetate, styrene-butadiene, vinyl chloride, acrylic-styrene, butadiene, styrene, crosslinked acrylic, crosslinked styrene, benzoguanamine, phenol, silicone, epoxy, urethane Resin of paraffin type, paraffin type and fluorine type. Of these, urethane is particularly preferably used from the viewpoint of improving the saturation of the formed image and ink dispersion stability when it is contained in the ink jet ink.
The emulsion of the urethane resin mentioned above includes an emulsion obtained by emulsifying a relatively hydrophilic ordinary polyurethane resin using an emulsifier on the outside, and means such as copolymerization of a functional group that functions as an emulsifier on the resin itself. There is a self-emulsifying emulsion introduced in. Either can be used.
The polyurethane resin emulsion is more preferably an anionic self-emulsifying polyurethane emulsion from the viewpoint of pigment dispersion stability.
The polyurethane-based resin is preferably a polyether-based, polyester-based, or polycarbonate-based from the viewpoints of ejection stability / dispersion stability, and more preferably a polycarbonate-based from the viewpoint of improving pigment fixing properties.

The glass transition point of the resin is preferably in the range of −50 to 0 ° C., more preferably in the range of −40 to −10 ° C.
The reason is not clear, but when the glass transition point exceeds 0 ° C., the film-forming property of the resin becomes glassy and hard, and the pigment particles and the resin land simultaneously on the object to be printed. It tends to become unexpectedly brittle.
On the other hand, when the glass transition point is −50 ° C. to 0 ° C., the resin film-forming property tends to be rubbery and soft and excellent in abrasion resistance.
In addition, the glass transition point of resin as used in the field of this invention is based on a DSC (Differential Scanning Calorimeter) measurement method.

The resin preferably has a minimum film-forming temperature of 60 ° C. or less, more preferably 50 ° C. or less from the viewpoints of industrial use and work / processing environment, and particularly heats an image-formed recording medium. Or 25 degrees C or less is more preferable from a viewpoint of making it bind to paper fiber, without performing processes, such as drying.
Here, the “minimum film-forming temperature” means that an aqueous resin emulsion obtained by dispersing a resin in water is thinly cast on a metal plate such as aluminum and is continuously transparent when the temperature is raised. The lowest temperature at which a film is formed. In the temperature range below the minimum film-forming temperature, a white powder is formed.
"Film-forming property" means that when resin fine particles are dispersed in water to form a resin emulsion, a resin film is formed when the water component that is a continuous layer of this resin emulsion is evaporated. Means. This resin film plays a role of firmly fixing the pigment in the ink to the surface of the recording medium. Thus, it is considered that an image excellent in abrasion resistance and water resistance can be realized.

In the ink set of the present invention, the dispersion average particle size of the resin particles of the resin emulsion contained in the ink containing the water-insoluble colorant particles having a dispersion average particle size of 5 to 50 nm needs to be 1 to 50 nm or less. is there. By using the resin emulsion in this range, the printed matter recorded using the ink set of the present invention is excellent in abrasion resistance and water resistance.
The reason for this is not clear, but I guess as follows.

  When the dispersion average particle diameter of the resin emulsion particles is larger than 50 nm, the dispersion particle diameter of the resin emulsion particles is larger than the water-insoluble colorant particles dispersed in the ink. In such a state, when the ink is applied to the recording medium, the water-insoluble colorant particles and the resin emulsion contained in the ink are not uniformly dispersed, and the water-insoluble colorant is unevenly distributed and aggregated or fixed. As a result, an image is formed. In this case, the aggregated water-insoluble colorant particles scatter light, leading to a decrease in the saturation of the printed portion. Further, when the dispersion average particle diameter of the resin emulsion particles is larger than 50 nm, light scattering by the resin emulsion particles becomes remarkable, and the image saturation of the print portion is lowered and the density is not uniform.

  Furthermore, since the agglomerated portion of the unevenly distributed water-insoluble colorant particles has a weak fixing force, poor fixing of the printed portion and a decrease in abrasion resistance occur. In particular, when the dispersion average particle diameter of the water-insoluble colorant particles is 50 nm or less and is monodispersed (that the particle size distribution of the dispersion average particle diameter is narrow), this phenomenon occurs more remarkably.

In addition, when an ink having a dispersion average particle size of water-insoluble colorant particles of 50 nm or less is printed on a recording medium having fine irregularities on the surface, the particle size of the water-insoluble colorant particles is very fine. For this reason, the water-insoluble colorant particles are likely to be unevenly distributed in the concave portions of the recording medium, or more easily settle due to a capillary phenomenon or the like, the image saturation of the printed portion is lowered, and the density becomes nonuniform.
In the present invention, since resin emulsion particles having a dispersion average particle diameter of 50 nm or less are used, such sedimentation and uneven distribution of water-insoluble colorant particles hardly occur, and an image having high saturation and uniform density can be obtained. I can do it.

  In addition, when used in combination with yellow ink containing water-insoluble colorant particles having a dispersion average particle size of 60 nm or more, when forming an image on a recording medium with a single color or in combination with other colors (so-called secondary color or tertiary color, etc.) Even in this case, since the change in saturation and density is small, in a printed matter (for example, a picture image) printed in full color, the color tone and gloss balance of the whole printed matter become good.

  Thus, at least one ink different from the yellow ink contains water-insoluble colorant particles having a dispersion average particle diameter of 5 to 50 nm or less, and the dispersion average particle diameter of the resin emulsion particles contained in the ink is 1 From 1 to 40 nm is preferable from the viewpoint of improving the balance between the color tone and gloss of the entire printed matter printed in full color, and 1 to 35 nm is most preferable from the viewpoint of improving the abrasion resistance of the printed portion. If the dispersion average particle diameter of the resin emulsion particles is less than 1 nm, the dispersion stability of the ink cannot be maintained.

The yellow ink in the present invention includes water-insoluble colorant particles having a dispersion average particle diameter of 60 nm to 200 nm. From the viewpoint of further improving the abrasion resistance of the printed portion, the resin emulsion particles have a dispersion average particle diameter of 1 to 1. It is preferable that the resin emulsion which is 60 nm is included.
The resin emulsion particles are more preferably 1 to 50 nm from the viewpoint of enhancing gloss.
When used in combination with the ink containing water-insoluble colorant particles having a dispersion average particle size of 5 to 50 nm, the range of 1 to 35 nm is the most from the viewpoint of improving the balance between the color tone and gloss of the entire picture image printed in full color. preferable.
If the dispersion average particle size of the resin emulsion particles is larger than 60 nm, the scattering component due to the resin particles tends to increase.

  When the ink in the present invention contains a resin emulsion, the content as resin emulsion particles is preferably 1% by mass or more and 20% by mass or less, more preferably 5% by mass or more and 10% by mass with respect to the total mass of the ink. It is below mass%. When the content of the resin emulsion particles is less than 1% by mass, the abrasion resistance and the printing density of the image portion are insufficient, and when the content is more than 20% by mass, the viscosity of the ink is too high and printing becomes difficult. There is.

<Water-soluble solvent>
In the ink of the present invention, the water-soluble solvent can be used for the purpose of an anti-drying agent, a wetting agent or a penetration accelerator.
Anti-drying agents are used for the purpose of preventing clogging due to drying of the ink used as ink-jet ink at the ink ejection port of the nozzle. Solvents are preferred.
In addition, a water-soluble organic solvent is preferably used as a penetration accelerator for the purpose of allowing the ink used as the inkjet ink to penetrate better into the paper.

  Examples of water-soluble organic solvents include glycerin, 1,2,6-hexanetriol, trimethylolpropane, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, dipropylene glycol, 2-butene -1,4-diol, 2-ethyl-1,3-hexanediol, 2-methyl-2,4-pentanediol, 1,2-octanediol, 1,2-hexanediol, 1,2-pentanediol, Alkanediols (polyhydric alcohols) such as 4-methyl-1,2-pentanediol; glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glucitol, maltose, cellobiose, lacto Sugars such as sucrose, trehalose, maltotriose; sugar alcohols; hyaluronic acids; so-called solid wetting agents such as ureas; alkyl alcohols having 1 to 4 carbon atoms such as ethanol, methanol, butanol, propanol, isopropanol; Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol mono -Iso-propyl ether, ethylene glycol mono-n-butyl ether, Lenglycol mono-t-butyl ether, diethylene glycol mono-t-butyl ether, 1-methyl-1-methoxybutanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl Glycol ethers such as ether, propylene glycol mono-iso-propyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-iso-propyl ether; 2 -Pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, formamide, aceto Examples include amide, dimethyl sulfoxide, sorbit, sorbitan, acetin, diacetin, triacetin, sulfolane and the like, and one or more of these can be used.

  For the purpose of drying inhibitors and wetting agents, polyhydric alcohols are useful. For example, glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-butanediol. 2,3-butanediol, 1,4-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, tetraethylene glycol, 1,6-hexanediol, 2-methyl-2, Examples include 4-pentanediol, polyethylene glycol, 1,2,4-butanetriol, 1,2,6-hexanetriol, and the like. These may be used individually by 1 type and may use 2 or more types together.

  For the purpose of the penetrant, a polyol compound is preferable. Examples of the aliphatic diol include 2-ethyl-2-methyl-1,3-propanediol, 3,3-dimethyl-1,2-butanediol, 2, 2-diethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2,4-dimethyl-2,4-pentanediol, 2,5-dimethyl-2,5-hexane Examples include diol, 5-hexene-1,2-diol, and 2-ethyl-1,3-hexanediol. Among these, preferred examples include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol.

The water-soluble solvent used in the present invention may be used alone or in combination of two or more. The content of the water-soluble solvent is 1 to 60% by mass, preferably 5 to 40% by mass, more preferably 10 to 30% by mass.
Although there is no restriction | limiting in particular in the addition amount of the water used for this invention, Preferably it is 10 to 99 mass%, More preferably, it is 30 to 80 mass%. More preferably, it is 50 mass% or more and 70 mass% or less.

<Surfactant>
Examples of the surface tension adjusting agent include nonionic, cationic, anionic and betaine surfactants. The addition amount of the surface tension adjusting agent is preferably an amount that adjusts the surface tension of the ink in the present invention to 20 to 60 mN / m, more preferably 20 to 45 mN / m, in order to achieve good ink jetting. Preferably, the amount can be adjusted to 25 to 40 mN / m.
As the surfactant, a compound having a structure having both a hydrophilic part and a hydrophobic part in the molecule can be used effectively. Anionic surfactant, cationic surfactant, amphoteric surfactant, nonionic surfactant Any of the surfactants can be used. Furthermore, the above-mentioned polymer substance (polymer dispersing agent) can also be used as a surfactant.

Specific examples of anionic surfactants include, for example, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium alkyldiphenyl ether disulfonate, sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate, sodium stearate, potassium oleate, sodium dioctyl Sulfosuccinate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, sodium dialkylsulfosuccinate, sodium stearate, sodium oleate, t-octylphenoxyethoxypolyethoxyethyl Examples include sodium sulfate, etc., and select one or more of these Rukoto can.
Specific examples of the nonionic surfactant include, for example, polyoxyethylene lauryl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene oleyl phenyl ether, polyoxyethylene nonyl phenyl ether, oxyethylene / oxypropylene block copolymer, t- Examples include octylphenoxyethyl polyethoxyethanol, nonylphenoxyethyl polyethoxyethanol, and the like, and one or more of these can be selected.
Examples of the cationic surfactant include tetraalkylammonium salts, alkylamine salts, benzalkonium salts, alkylpyridium salts, imidazolium salts, and the like. Specific examples thereof include dihydroxyethyl stearylamine and 2-heptadecenyl. -Hydroxyethyl imidazoline, lauryl dimethyl benzyl ammonium chloride, cetyl pyridinium chloride, stearamide methyl pyridium chloride and the like.
The amount of the surfactant added to the ink in the present invention is not particularly limited, but is preferably 0.1% by mass or more, more preferably 0.5 to 10% by mass, and still more preferably 1%. ~ 3% by mass.

<Other ingredients>
The ink in the present invention may contain other additives. Other additives include, for example, ultraviolet absorbers, anti-fading agents, anti-mold agents, pH adjusters, rust inhibitors, antioxidants, emulsion stabilizers, preservatives, antifoaming agents, viscosity modifiers, and dispersion stabilizers. Known additives such as agents and chelating agents are included.

  Examples of the UV absorber include benzophenone UV absorbers, benzotriazole UV absorbers, salicylate UV absorbers, cyanoacrylate UV absorbers, nickel complex salt UV absorbers, and the like.

  As the antifading agent, various organic and metal complex antifading agents can be used. Organic anti-fading agents include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, heterocycles, etc. Complex, zinc complex and the like.

  Antifungal agents include sodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide, p-hydroxybenzoic acid ethyl ester, 1,2-benzisothiazolin-3-one, sodium sorbate, sodium pentachlorophenol, etc. Can be mentioned. These are preferably used in the ink in an amount of 0.02 to 1.00% by mass.

  The pH adjuster is not particularly limited as long as it can adjust the pH to a desired value without adversely affecting it, and can be appropriately selected according to the purpose. For example, alcohol amines (for example, diethanolamine, Triethanolamine, 2-amino-2-ethyl-1,3-propanediol, etc.), alkali metal hydroxides (eg lithium hydroxide, sodium hydroxide, potassium hydroxide etc.), ammonium hydroxides (eg water Ammonium oxide, quaternary ammonium hydroxide), phosphonium hydroxide, alkali metal carbonate and the like.

  Examples of the rust inhibitor include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

  Examples of the antioxidant include phenol antioxidants (including hindered phenol antioxidants), amine antioxidants, sulfur antioxidants, phosphorus antioxidants, and the like.

  Examples of the chelating agent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, sodium uramil diacetate and the like.

(Liquid composition for improving printability)
In the present invention, a liquid composition for improving printability may be applied to a recording medium.
A preferred example of the liquid composition that can be used in the present invention to improve the printability is a liquid composition that generates an aggregate by changing the pH of the ink. At this time, the pH of the liquid composition is preferably 1 to 6, more preferably 2 to 5, and still more preferably 3 to 5. As components of the liquid composition, polyacrylic acid, acetic acid, glycolic acid, malonic acid, malic acid, maleic acid, ascorbic acid, succinic acid, glutaric acid, fumaric acid, citric acid, tartaric acid, lactic acid, sulfonic acid, orthophosphoric acid, It is preferably selected from pyrrolidone carboxylic acid, pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, derivatives of these compounds, or salts thereof. . These compounds may be used alone or in combination of two or more.

  A preferred example of a liquid composition that can be used in the present invention to improve printability is a treatment liquid to which a polyvalent metal salt or polyallylamine is added. As a component of the liquid composition, as a polyvalent metal salt, an alkaline earth metal of Group 2A of the periodic table (for example, magnesium and calcium); a transition metal of Group 3B of the periodic table (for example, lanthanum); from Group 3A of the periodic table Cations (for example, aluminum); lanthanides (for example, neodymium); and polyallylamine and polyallylamine derivatives. Preferred examples include calcium and magnesium. Anions that are preferably employed as a counter salt of calcium or magnesium include carboxylate (formic acid, acetic acid, benzoate, etc.), nitrate, chloride, and thiocyanate. As an addition amount to the treatment liquid, the salt is contained in the treatment liquid in an amount ranging from about 1 to about 10% by weight, preferably from about 1.5 to about 7% by weight, more preferably from about 2 to about 6% by weight. Can exist.

(Physical properties of ink and liquid composition)
The surface tension of the ink and the liquid composition is preferably 20 mN / m or more and 60 mN / m or less. More preferably, it is 20 mN or more and 45 mN / m or less, More preferably, it is 25 mN / m or more and 40 mN / m or less.
The viscosity of the ink and the liquid composition at 20 ° C. is preferably 1.2 mPa · s or more and 15.0 mPa · s or less, more preferably 2 mPa · s or more and less than 13 mPa · s, and further preferably 2.5 mPa · s. · It is s or more and less than 10 mPa · s.

<Inkjet recording method, printed matter>
The inkjet recording method of the present invention is a recording method using the ink set of the present invention. As a preferred ink jet recording method of the present invention, energy is supplied to the ink in the ink set, and a known recording medium, that is, plain paper, resin-coated paper, for example, JP-A-8-169172 and 8-27693. JP-A-2-276670, JP-A-7-276789, JP-A-9-323475, JP-A-62-238783, JP-A-10-153789, JP-A-10-217473, JP-A-10-235995. No. 10-337947, No. 10-217597, No. 10-337947, etc., such as dedicated inkjet paper, film, electrophotographic paper, cloth, glass, metal, ceramics, etc. It is a method of forming. In addition, the description of paragraph numbers 0093 to 0105 in JP-A No. 2003-306623 can be applied as an ink jet recording method preferable for the present invention.

The printed matter of the present invention is recorded using the ink set of the present invention, and more specifically, the printed matter is preferably recorded on the recording medium by the ink jet recording method. . The above-mentioned recording media can be used.
The printed material obtained in this way has a wide color reproduction range that is measured and calculated using color patches, etc., and in a printed material printed in full color, the color balance is visually excellent. Can have a smooth color tone.

  In forming an image, a polymer latex compound may be used in combination for the purpose of imparting glossiness or water resistance or improving weather resistance. The timing of applying the latex compound to the image receiving material may be before, after, or simultaneously with the application of the colorant, and therefore the addition location may be in the image receiving paper. It may be in ink or may be used as a liquid material of polymer latex alone. Specifically, JP 2002-166638 (Japanese Patent Application 2000-363090), JP 2002-121440 (Japanese Patent Application 2000-315231), JP 2002-154201 (Japanese Patent Application 2000-354380), JP 2002-144696 ( The methods described in Japanese Patent Application No. 2000-343944) and Japanese Patent Application Laid-Open No. 2002-080759 (Japanese Patent Application No. 2000-268952) can be preferably used.

As an example of a preferred image forming method for the present invention,
1st process: The process of providing the liquid composition which improves printability to a recording medium.
Second step: a step of applying ink of an ink set to a recording medium to which the liquid composition is applied.
Other steps: Other steps are not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a drying removal step and a heat fixing step. The drying removal step is not particularly limited except that the ink solvent in the ink composition applied to the recording medium is removed by drying, and can be appropriately selected according to the purpose. The heat fixing step is not particularly limited except that the latex particles contained in the ink used in the ink jet recording method are melt-fixed, and can be appropriately selected depending on the purpose.

As another example of an image forming system preferable for the present invention,
1st process: The process of providing the liquid composition which improves printability to an intermediate transfer body.
Second step: a step of applying ink of an ink set to the intermediate transfer body to which the liquid composition has been applied.
Third step: a step of transferring an ink image formed on the intermediate transfer member to a recording medium.
Other steps: Other steps are not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a drying removal step and a heat fixing step.

  The present invention will be described below in more detail based on examples, but the present invention is not limited to these examples. In the text, “parts” and “%” are based on mass unless otherwise specified.

(Measurement of volume average particle diameter and number average particle diameter by dynamic light scattering method)
The average particle size of each ink described below by dynamic light scattering is determined by diluting the ink with ultrapure water at the dilution ratio of each ink, and at 25 ° C., the particle permeability is “transmitted” and the particle shape is “ The measurement was performed under the measurement conditions of “non-spherical” and particle density “1.2”.
The average particle diameter of each pigment dispersion described below by the dynamic light scattering method was diluted with ultrapure water, and then measured using Microtrac (Version 10.1.2-211BH) manufactured by Nikkiso Co., Ltd.
At this time, in addition to the volume average particle diameter Mv of each dispersion, the number average particle diameter Mn was also measured.
At the same time, D90, D50 and D10 (respectively equal to 0.9 (90 number%), 0.5 (50 number%) and 0.1 (10 number%) of the total number of pigment particles are represented. ) Was calculated, and the polydispersity index (PDI: polydispersity index) of the following formula (1) was estimated.

Formula (1)
PDI = (D ₉₀ -D ₁₀ ) / D ₅₀

(Measurement of average particle diameter by observation with a transmission electron microscope (TEM))
The average particle diameter evaluation by observation with a transmission electron microscope (TEM) was performed by dropping the diluted dispersion on Cu200 mesh with a carbon film attached and then drying, and the magnification was increased 100,000 times with TEM (JEOL 1200EX). From the images, the major axis of 300 independent non-overlapping particles was measured and the average value was calculated as the average particle size (hereinafter, the average particle size calculated by TEM observation is described as the TEM average particle size).

<Polymer synthesis example>
(Polymer synthesis example 1)
The inside of a 2000 ml separable flask equipped with a stirrer, a reflux tube, a thermometer, and a dropping funnel was purged with nitrogen, and then 200.0 parts of diethylene glycol monomethyl ether was placed in the separable flask and heated to 80 ° C. while stirring. Next, 200.0 parts of diethylene glycol monomethyl ether, 483.0 parts of benzyl acrylate, 50.4 parts of acrylic acid and 4.8 parts of t-butylperoxy (2-ethylhexanoate) are put into a dropping funnel at 80 ° C. It was made to react by dripping in a separable flask over 4 hours. After completion of the dropwise addition, the mixture was kept at 80 ° C. for 1 hour, 0.8 parts of t-butylperoxy (2-ethylhexanoate) was added, and the reaction was further carried out at 80 ° C. for 1 hour. Thereafter, diethylene glycol monomethyl ether was removed by distillation under reduced pressure. Then, 600.0 parts of methyl ethyl ketone was added to obtain a polymer composition solution having a resin solid content of 50%. After taking a part of the polymer composition solution thus obtained and drying for 1 hour in an ignition dryer at 105 ° C., the acid value of the solid matter of the polymer composition obtained is 65 mgKOH / g, The weight average molecular weight was 34,000.

(Polymer synthesis example 2)
A polymer was synthesized in the same manner as in Polymer Synthesis Example 1 except that 77.5 parts of acrylic acid was used instead of 50.4 parts of acrylic acid. After taking 1 part of this polymer composition solution and drying it with a dryer at 105 ° C. for 1 hour, the resulting polymer composition had an acid value of 100 mg KOH / g and a weight average molecular weight of 29000. .

(Polymer synthesis example 3)
A polymer was synthesized in the same manner as in Polymer Synthesis Example 1 except that 100.8 parts of acrylic acid was used instead of 50.4 parts of acrylic acid. After taking 1 part of this polymer composition solution and drying it with a dryer at 105 ° C. for 1 hour, the resulting polymer composition had a solid acid value of 130 mgKOH / g and a weight average molecular weight of 29000. .

(Polymer synthesis example 4)
A polymer was synthesized in the same manner as in Polymer Synthesis Example 1 except that 116.3 parts of acrylic acid was used instead of 50.4 parts of acrylic acid. After taking 1 part of this polymer composition solution and drying it with a dryer at 105 ° C. for 1 hour, the resulting polymer composition had a solid acid value of 150 mgKOH / g and a weight average molecular weight of 34,000. .

<Preparation of water-insoluble colorant particle dispersion>
(Preparation of yellow inks A-1 and A-2)
To 120.0 parts of the polymer composition solution prepared in Polymer Synthesis Example 1, 3.0 parts of a 30% aqueous sodium hydroxide solution was added and stirred for 5 minutes with a high-speed disper. I. 480.0 parts of PY74 was added and stirred with a high-speed disper for 1 hour to obtain a pigment-dispersed slurry.
The pigment dispersion slurry was repeatedly dispersed 10 times at a pressure of 200 MPa with an ultrahigh pressure homogenizer (Microfluidizer, manufactured by Mizuho Kogyo Co., Ltd.) to obtain a pigment dispersion.

Further, methyl ethyl ketone and a part of water were distilled off from the pigment dispersion thus obtained by vacuum distillation using an evaporator, and centrifuged at 5000 rpm for 30 minutes with a centrifuge (05P-21, manufactured by Hitachi, Ltd.). After that, ion-dispersed water was added to adjust the pigment dispersion A so that the pigment concentration was 15%.
And it pressure-filtered using the 2.5 micrometer membrane filter (made by Advantech).
After the pigment dispersion A was diluted with ultrapure water so that the pigment concentration became 0.1%, the volume average particle size determined by the dynamic light scattering method was 105.7 nm (TEM average particle size: 61.5 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersibility, was 1.64.
This pigment dispersion A and the resin emulsion shown in Table 1 were combined to produce yellow ink A-1 and yellow ink A-2 having the ink composition shown in Table 3, and the ink was then added 1000 times with ultrapure water. After dilution, the volume average particle diameter (TEM average particle diameter) and volume average particle diameter Mv / number average particle diameter Mn determined by the dynamic light scattering method were measured.

(Preparation of yellow ink B)
In the production of yellow ink A, stirring using a high-speed disper was performed using Asako Steel Co., Ltd. Picomill (dispersion media: zirconia, temperature: 20 ° C., dispersion media / liquid separation weight ratio: 8/2) and a peripheral speed of 8 m. Pigment dispersion B was obtained in the same manner except that the dispersion treatment was changed to 12.5 hours at / s.
After this pigment dispersion B was diluted with ultrapure water so that the pigment concentration was 0.1%, the volume average particle size determined by the dynamic light scattering method was 80.3 nm (TEM average particle size: 54.8 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersity, was 1.45.
This pigment dispersion B and the resin emulsion shown in Table 1 are combined to produce a yellow ink B having the ink composition shown in Table 3. Thereafter, the ink is diluted 1000 times with ultrapure water, and the dynamic light scattering method is used. The obtained volume average particle diameter (TEM average particle diameter), volume average particle diameter Mv / number average particle diameter Mn were measured.

(Preparation of yellow ink C)
A pigment dispersion C was obtained in the same manner as in the production of yellow ink B, except that the processing conditions of Asahi Steel Co., Ltd. Picomill were changed to a peripheral speed of 13 m / s and a processing time of 2 hours.
After the pigment dispersion C was diluted with ultrapure water so as to have a pigment concentration of 0.1%, the volume average particle size determined by the dynamic light scattering method was 120.3 nm (TEM average particle size: 71.4 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersibility, was 1.66.
This pigment dispersion C and the resin emulsion shown in Table 1 are combined to produce a yellow ink C having the ink composition shown in Table 3. Thereafter, the ink is diluted 1000 times with ultrapure water, and the dynamic light scattering method is used. The obtained volume average particle diameter (TEM average particle diameter), volume average particle diameter Mv / number average particle diameter Mn were measured.

(Preparation of yellow ink D)
As a dispersant, 10 parts of a dried product of the polymer composition solution prepared in Polymer Synthesis Example 2 was dissolved in 80 parts of dimethyl sulfoxide. I. 10 parts of PY128 were suspended in a flask at 25 ° C. under an air atmosphere. Next, a 25% tetramethylammonium hydroxide methanol solution (manufactured by Wako Pure Chemical Industries, Ltd.) was dropped in small portions to dissolve the pigment, thereby obtaining a red solution. After stirring this pigment solution for 3 hours, the system dispenser (Musashi Engineering Co., Ltd.) was added to the cooled and kept ion-exchanged water (400 parts: 0 ° C. for 10 parts of pigment) stirred with an impeller-type stirring blade (800 rpm). Made by a company, needle inner diameter: 0.58 mm, discharge pressure: 4.0 kgf / cm ² ), and rapidly charged to obtain an aqueous dispersion of pigment-containing particles having a volume average particle diameter of 39.8 nm.

  Next, a 5% aqueous sulfuric acid solution was dropped into the aqueous dispersion of pigment-containing particles to adjust the pH to 4.0, and the pigment-containing particles were aggregated from the aqueous dispersion of pigment-containing particles. Thereafter, the agglomerate is filtered under reduced pressure using a membrane filter (retained particle size is 0.45 μm), washed three times with ion-exchanged water (500 parts), and the aqueous dispersion of the pigment-containing particles is desalted and desolvated. A body paste was obtained.

Next, 2.0 g of potassium hydroxide was added to this paste, and then ion-exchanged water was added so that the total mass became 100 g, followed by stirring for 1 hour. Thereafter, potassium hydroxide was added to adjust the pH to 9.5 to obtain a pigment dispersion D having a pigment content of 10% by weight.
After the pigment dispersion D was diluted with ultrapure water so that the pigment concentration was 0.1%, the volume average particle size determined by the dynamic light scattering method was 43.2 nm (TEM average particle size: 33.6 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersity, was 1.37, and the film had high transparency.
The pigment dispersion D and the resin emulsion shown in Table 1 are combined to produce a yellow ink D having the ink composition shown in Table 3. Thereafter, the ink is diluted 40 times with ultrapure water, and the dynamic light scattering method is used. The obtained volume average particle diameter (TEM average particle diameter), volume average particle diameter Mv / number average particle diameter Mn were measured.

(Preparation of yellow inks E-1 to E-3)
Pigment dispersion E was obtained in the same manner except that the polymer composition solution used in the preparation of yellow ink B was changed to the polymer composition solution prepared in Polymer Synthesis Example 2.
After the pigment dispersion E was diluted with ultrapure water so that the pigment concentration became 0.1%, the volume average particle size determined by the dynamic light scattering method was 70.5 nm (TEM average particle size: 45.1 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersibility, was 1.60.
This pigment dispersion E and the resin emulsion shown in Table 1 were combined to produce yellow inks E-1 to E-3 having the ink composition shown in Table 3, and then the ink was diluted 1000 times with ultrapure water, The volume average particle diameter (TEM average particle diameter) and volume average particle diameter Mv / number average particle diameter Mn determined by the dynamic light scattering method were measured.

(Preparation of yellow ink F)
Pigment dispersion F was obtained in the same manner as in the preparation of yellow ink A, except that the processing conditions of an ultrahigh pressure homogenizer (Microfluidizer, manufactured by Mizuho Kogyo Co., Ltd.) were changed to a pressure of 200 MPa and the number of continuous repetitions was 8.
After the pigment dispersion F was diluted with ultrapure water so as to have a pigment concentration of 0.1%, the volume average particle size determined by the dynamic light scattering method was 160.1 nm (TEM average particle size: 90.8 nm) The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersibility, was 1.72.
This pigment dispersion F and the resin emulsion shown in Table 1 are combined to produce a yellow ink F having the ink composition shown in Table 3. Thereafter, the ink is diluted 1000 times with ultrapure water, and subjected to a dynamic light scattering method. The obtained volume average particle diameter (TEM average particle diameter), volume average particle diameter Mv / number average particle diameter Mn were measured.

(Preparation of yellow ink G)
The yellow pigment used in the production of yellow ink F is C.I. I. A pigment dispersion G was obtained in the same manner except that the amount was changed to 480.0 parts of PY155.
After the pigment dispersion G was diluted with ultrapure water so as to have a pigment concentration of 0.1%, the volume average particle size determined by the dynamic light scattering method was 186.4 nm (TEM average particle size: 100.3 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersibility, was 1.75.
This pigment dispersion G and the resin emulsion shown in Table 1 are combined to produce a yellow ink G having the ink composition shown in Table 3. Thereafter, the ink is diluted 1000 times with ultrapure water, and the dynamic light scattering method is used. The obtained volume average particle diameter (TEM average particle diameter), volume average particle diameter Mv / number average particle diameter Mn were measured.

(Preparation of yellow ink H)
A pigment dispersion H was obtained in the same manner as in the preparation of the yellow ink F, except that the processing conditions of an ultrahigh pressure homogenizer (Microfluidizer, manufactured by Mizuho Kogyo Co., Ltd.) were changed to a pressure of 200 MPa and the number of continuous repetitions was 7.
After the pigment dispersion H was diluted with ultrapure water so as to have a pigment concentration of 0.1%, the volume average particle size determined by the dynamic light scattering method was 208.3 nm (TEM average particle size: 118.1 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersibility, was 1.70.
This pigment dispersion H and the resin emulsion shown in Table 1 are combined to produce a yellow ink H having the ink composition shown in Table 3. Thereafter, the ink is diluted 1000 times with ultrapure water, and the dynamic light scattering method is used. The obtained volume average particle diameter (TEM average particle diameter), volume average particle diameter Mv / number average particle diameter Mn were measured.

(Preparation of yellow ink I)
Pigment dispersion I was obtained in the same manner as in the preparation of yellow ink F, except that the processing conditions of an ultrahigh pressure homogenizer (Microfluidizer, manufactured by Mizuho Kogyo Co., Ltd.) were changed to a pressure of 200 MPa and the number of continuous repetitions was six.
After this pigment dispersion I was diluted with ultrapure water so as to have a pigment concentration of 0.1%, the volume average particle size determined by the dynamic light scattering method was 245.6 nm (TEM average particle size: 123.8 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersibility, was 1.81.
This pigment dispersion I and the resin emulsion shown in Table 1 are combined to produce a yellow ink I having the ink composition shown in Table 3. Thereafter, the ink is diluted 1000 times with ultrapure water, and the dynamic light scattering method is used. The obtained volume average particle diameter (TEM average particle diameter), volume average particle diameter Mv / number average particle diameter Mn were measured.

(Preparation of magenta inks J-1 to J-4)
As a dispersant, 10 parts of a dried product of the polymer composition solution prepared in Polymer Synthesis Example 3 was dissolved in 80 parts of dimethyl sulfoxide. I. 10 parts of PR122 quinacridone pigment was suspended in a flask at 25 ° C. in an air atmosphere. Next, a 25% tetramethylammonium hydroxide methanol solution (manufactured by Wako Pure Chemical Industries, Ltd.) was dropped in small portions to dissolve the pigment, and a dark blue-violet solution was obtained.
After stirring this pigment solution for 3 hours, the system dispenser (Musashi Engineering Co., Ltd.) was added to the cooled and kept ion-exchanged water (400 parts: 0 ° C. for 10 parts of pigment) stirred with an impeller-type stirring blade (800 rpm). Made by a company, needle inner diameter: 0.58 mm, discharge pressure: 4.0 kgf / cm ² ), and rapidly charged to obtain an aqueous dispersion of transparent and reddish pigment-containing particles.
The volume average particle diameter of the aqueous dispersion of pigment-containing particles determined by the dynamic light scattering method is 30.0 nm (TEM average particle diameter: 23.0 nm), and the volume average particle diameter Mv, which is an index of monodispersity. The ratio of / number average particle diameter Mn was 1.19.

  Next, concentrated hydrochloric acid was added dropwise to the pigment-containing particle aqueous dispersion to adjust the pH to 3.5, and the pigment-containing particles were aggregated from the pigment-containing particle aqueous dispersion. Thereafter, this aggregate is filtered under reduced pressure using a membrane filter (average pore size 0.2 μm), washed twice with 500 parts of ion-exchanged water, and a paste of an aqueous dispersion of pigment-containing particles that has been desalted and desolvated is obtained. Obtained.

  Next, 100 parts of acetone was added to the paste, followed by stirring and ultrasonic treatment. Then, it filtered under reduced pressure using the membrane filter (average pore diameter of 0.2 micrometer), and obtained the paste of the aqueous dispersion containing a pigment containing particle | grain. This paste was washed with ion-exchanged water and filtered under reduced pressure again using a membrane filter (average pore size 0.2 μm) to obtain a paste of an aqueous dispersion of pigment-containing particles.

Next, a small amount of ion-exchanged water was added to this paste, and after further adding a 15% tetramethylammonium hydroxide aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.), ion-exchanged water was added and stirred for 1 hour. Thereafter, ion-exchanged water was added so that the pigment content was 10%. Further, 15% tetramethylammonium hydroxide aqueous solution was added to adjust the pH to 9.5, and then pigment dispersion J was obtained.
After this pigment dispersion J was diluted with ultrapure water so as to have a pigment concentration of 0.1%, the volume average particle size determined by the dynamic light scattering method was 30.5 nm (TEM average particle size: 25.3 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersity, was 1.17. No change was observed in the particle size after storage for 2 weeks, no sediment was observed, and no discoloration was observed.
This pigment dispersion J and the resin emulsion shown in Table 1 were combined to produce magenta inks J-1 to J-4 having the ink composition shown in Table 3, and then the ink was diluted 40 times with ultrapure water, The volume average particle diameter (TEM average particle diameter) and volume average particle diameter Mv / number average particle diameter Mn determined by the dynamic light scattering method were measured.

(Preparation of magenta ink K)
As a dispersant, 10 parts of a dried product of the polymer composition solution prepared in Polymer Synthesis Example 4 was dissolved in 80 parts of dimethyl sulfoxide. I. Ten parts of PV19 quinacridone pigment was suspended in a flask at 25 ° C. in an air atmosphere. Next, a 25% tetramethylammonium hydroxide methanol solution (manufactured by Wako Pure Chemical Industries, Ltd.) was dropped in small portions to dissolve the pigment, and a dark blue-violet solution was obtained. After stirring this pigment solution for 3 hours, the system dispenser (Musashi Engineering Co., Ltd.) was added to the cooled and kept ion-exchanged water (400 parts: 0 ° C. for 10 parts of pigment) stirred with an impeller-type stirring blade (800 rpm). Made by a company, needle inner diameter: 0.58 mm, discharge pressure: 4.0 kgf / cm ² ), and rapidly charged to obtain an aqueous dispersion of transparent and reddish pigment-containing particles.
The volume average particle size of the pigment dispersion determined by the dynamic light scattering method is 21.5 nm (TEM average particle size: 17.7 nm), and the volume average particle size Mv / number average particle, which is an index of monodispersity. The ratio of the diameter Mn was 1.18.

  Next, concentrated hydrochloric acid was added dropwise to the pigment-containing particle aqueous dispersion to adjust the pH to 3.5, and the pigment-containing particles were aggregated from the pigment-containing particle aqueous dispersion. Thereafter, the agglomerate is filtered under reduced pressure using a membrane filter (average pore size 0.2 μm), washed twice with ion exchange water (500 parts), desalted and desolvated pigment-containing particle dispersion paste. Got.

  Next, 100 parts of acetone was added to the paste, followed by stirring and ultrasonic treatment. Thereafter, filtration under reduced pressure was performed using a membrane filter (average pore size 0.2 μm) to obtain a paste of an aqueous dispersion of pigment-containing particles. This paste was washed with ion-exchanged water and filtered under reduced pressure again using a membrane filter (average pore size 0.2 μm) to obtain a paste of an aqueous dispersion of pigment-containing particles.

Next, a small amount of ion-exchanged water was added to this paste, and after further adding a 15% tetramethylammonium hydroxide aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.), ion-exchanged water was added and stirred for 1 hour. Thereafter, ion-exchanged water was added so that the pigment content was 10%. Further, 15% tetramethylammonium hydroxide aqueous solution was added to adjust the pH to 9.5, and then a pigment dispersion K was obtained.
After this pigment dispersion K was diluted with ultrapure water so as to have a pigment concentration of 0.1%, the volume average particle size determined by the dynamic light scattering method was 22.3 nm (TEM average particle size: 18.3 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersity, was 1.17. No change was observed in the particle size after storage for 2 weeks, no sediment was observed, and no discoloration was observed.
The pigment dispersion K and the resin emulsion shown in Table 1 are combined to produce a magenta ink K having the ink composition shown in Table 3. Thereafter, the ink is diluted 40 times with ultrapure water, and the dynamic light scattering method is used. The obtained volume average particle diameter (TEM average particle diameter), volume average particle diameter Mv / number average particle diameter Mn were measured.

(Preparation of magenta ink L)
Similarly to the preparation of Pigment Dispersion Liquid J, 10 parts of a dried product of the polymer composition solution prepared in Polymer Synthesis Example 3 as a dispersant was dissolved in 80 parts of dimethyl sulfoxide. I. 10 parts of PR122 quinacridone pigment was suspended in a flask at 25 ° C. in an air atmosphere. Next, a 25% tetramethylammonium hydroxide methanol solution (manufactured by Wako Pure Chemical Industries, Ltd.) was dropped in small portions to dissolve the pigment, and a dark blue-violet solution was obtained.
After stirring this pigment solution for 3 hours, the system dispenser (Musashi Engineering Co., Ltd.) was added to the cooled and kept ion-exchanged water (400 parts: 0 ° C. for 10 parts of pigment) stirred with an impeller-type stirring blade (800 rpm). Made by a company, needle inner diameter: 0.58 mm, discharge pressure: 4.0 kgf / cm ² ), and rapidly charged to obtain an aqueous dispersion of transparent and reddish pigment-containing particles.
The volume average particle size of the pigment dispersion determined by the dynamic light scattering method is 31.8 nm (TEM average particle size: 24.1 nm), and the volume average particle size Mv / number average particle, which is an index of monodispersity. The ratio of diameter Mn was 1.20.

  Next, concentrated hydrochloric acid was added dropwise to the pigment-containing particle aqueous dispersion to adjust the pH to 3.5, and the pigment-containing particles were aggregated from the pigment-containing particle aqueous dispersion. Thereafter, the agglomerate was filtered under reduced pressure using a membrane filter (average pore size 0.2 μm) and washed twice with 500 parts of ion-exchanged water to obtain a paste of a dispersion of pigment particles which has been desalted and desolvated. .

Next, a small amount of ion-exchanged water was added to this paste, and after further adding a 15% tetramethylammonium hydroxide aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.), ion-exchanged water was added and stirred for 1 hour. Thereafter, ion-exchanged water was added so that the pigment content was 10%. Further, 15% tetramethylammonium hydroxide aqueous solution was added to adjust the pH to 9.5, and then pigment dispersion L was obtained.
After this pigment dispersion L was diluted with ultrapure water so as to have a pigment concentration of 0.1%, the volume average particle size determined by the dynamic light scattering method was 31.4 nm (TEM average particle size: 25.5 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersibility, was 1.16. No change was observed in the particle size after storage for 2 weeks, no sediment was observed, and no discoloration was observed.
The pigment dispersion L and the resin emulsion shown in Table 1 are combined to produce a magenta ink L having the ink composition shown in Table 3. Thereafter, the ink is diluted 40 times with ultrapure water, and the dynamic light scattering method is used. The obtained volume average particle diameter (TEM average particle diameter), volume average particle diameter Mv / number average particle diameter Mn were measured.

(Preparation of magenta ink M)
In preparing the pigment dispersion J, C.I. I. 10 parts of quinacridone pigment of PR122 are added to C.I. I. PR 122 quinacridone pigment 5.2 parts and C.I. I. A pigment dispersion M was obtained in the same manner except that the PV19 quinacridone pigment was changed to 4.8 parts.
After this pigment dispersion M was diluted with ultrapure water so as to have a pigment concentration of 0.1%, the volume average particle size determined by the dynamic light scattering method was 35.3 nm (TEM average particle size: 28.1 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersibility, was 1.20. No change was observed in the particle size after storage for 2 weeks, no sediment was observed, and no discoloration was observed.
The pigment dispersion M and the resin emulsion shown in Table 1 are combined to produce a magenta ink M having the ink composition shown in Table 3. Thereafter, the ink is diluted 40 times with ultrapure water, and the dynamic light scattering method is used. The obtained volume average particle diameter (TEM average particle diameter), volume average particle diameter Mv / number average particle diameter Mn were measured.

(Preparation of magenta ink N)
A pigment dispersion N was obtained in the same manner as in the preparation of the pigment dispersion J, except that 10 parts of the dried polymer composition solution was changed to 4 parts.
After the pigment dispersion N was diluted 50 times with ultrapure water, the volume average particle size determined by the dynamic light scattering method was 48.1 nm (TEM average particle size: 39.8 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn as an index was 1.20. No change was observed in the particle size after storage for 2 weeks, no sediment was observed, and no discoloration was observed.
The pigment dispersion N and the resin emulsion shown in Table 1 are combined to produce a magenta ink N having the ink composition shown in Table 3. Thereafter, the ink is diluted 40 times with ultrapure water, and the dynamic light scattering method is used. The obtained volume average particle diameter (TEM average particle diameter), volume average particle diameter Mv / number average particle diameter Mn were measured.

(Preparation of magenta ink O)
In the preparation of yellow ink E, the yellow pigment C.I. I. 480.0 parts of PY74 were added to magenta pigment C.I. I. A pigment dispersion was obtained in the same manner except that PR122 was changed to 480.0 parts.
The supernatant obtained by centrifuging this pigment dispersion at 18000 rpm for 30 minutes in a centrifuge is concentrated and adjusted using an evaporator so that the pigment concentration becomes 10% by weight. Got.
After this pigment dispersion O was diluted with ultrapure water so as to have a pigment concentration of 0.1%, the volume average particle size determined by the dynamic light scattering method was 43.2 nm (TEM average particle size: 33.3 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersibility, was 1.69.
This pigment dispersion O and the resin emulsion shown in Table 1 are combined to produce a magenta ink O having the ink composition shown in Table 3. Thereafter, the ink is diluted 40 times with ultrapure water, and the dynamic light scattering method is used. The obtained volume average particle diameter (TEM average particle diameter), volume average particle diameter Mv / number average particle diameter Mn were measured.

(Preparation of magenta ink P)
In the preparation of yellow ink E, the yellow pigment C.I. I. 480.0 parts of PY74 was added to magenta pigment C.I. I. Pigment dispersion P was obtained in the same manner except that PR122 was changed to 480.0 parts.
After the pigment dispersion P was diluted with ultrapure water so as to have a pigment concentration of 0.1%, the volume average particle size determined by the dynamic light scattering method was 68.4 nm (TEM average particle size: 40.5 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersibility, was 1.70.
The pigment dispersion P and the resin emulsion shown in Table 1 are combined to produce a magenta ink P having the ink composition shown in Table 3. Thereafter, the ink is diluted 500 times with ultrapure water, and subjected to dynamic light scattering. The obtained volume average particle diameter (TEM average particle diameter), volume average particle diameter Mv / number average particle diameter Mn were measured.

(Preparation of cyan inks Q-1 to Q-4)
C. I. 3 parts of PB15: 3 and 6 parts of polyvinylpyrrolidone K25 (manufactured by Tokyo Kasei Kogyo Co., Ltd.) are added to 50 parts of methanesulfonic acid at room temperature and stirred for 2 hours. A solution was obtained.

After ultrasonically treating this pigment solution, a system dispenser (manufactured by Musashi Engineering Co., Ltd., needle inner diameter: 0.58 mm, discharge pressure: 1000 parts of cooled and heat-exchanged water stirred with an impeller type stirring blade (800 rpm). 4.0 kgf / cm ² ), which was quickly charged to obtain a transparent and bluish pigment dispersion.
After that, after purifying while adding distilled water with an ultrafiltration device (Advantech Toyo Co., Ltd., UHP-62K, molecular weight cut off 50,000) to eliminate the filtrate and concentrating to 10.0% of pigment. Thus, a pigment dispersion Q was obtained.
After the pigment dispersion Q was diluted with ultrapure water so as to have a pigment concentration of 0.1%, the volume average particle size determined by the dynamic light scattering method was 29.8 nm (TEM average particle size: 24.8 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersity, was 1.18.
Cyan ink Q-1 to Q-4 having the ink composition shown in Table 3 was prepared by combining this pigment dispersion Q and the resin emulsion shown in Table 1, and then the ink was diluted 40 times with ultrapure water, The volume average particle diameter (TEM average particle diameter) and volume average particle diameter Mv / number average particle diameter Mn determined by the dynamic light scattering method were measured.

(Preparation of cyan inks R-1 and R-2)
A pigment dispersion was obtained in the same manner as in the preparation of pigment dispersion Q, except that 6 parts of polyvinylpyrrolidone K25 (trade name) (manufactured by Tokyo Chemical Industry Co., Ltd.) was changed to 2.5 parts.
The obtained pigment dispersion was purified by adding distilled water with an ultrafiltration device (manufactured by Advantech Toyo Co., Ltd., UHP-62K, molecular weight cut off 50,000) to eliminate the filtrate and keeping the volume constant. The pigment dispersion R was obtained by concentrating to 0%.
After this pigment dispersion R was diluted with ultrapure water so as to have a pigment concentration of 0.1%, the volume average particle size determined by the dynamic light scattering method was 38.3 nm (TEM average particle size: 31.8 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersity, was 1.19.
This pigment dispersion R and the resin emulsion shown in Table 1 are combined to produce cyan ink R-1 and cyan ink R-2 having the ink composition shown in Table 3, and then the ink is diluted 40 times with ultrapure water. Then, the volume average particle diameter (TEM average particle diameter) and volume average particle diameter Mv / number average particle diameter Mn determined by the dynamic light scattering method were measured.

(Preparation of cyan ink S)
The pigment used in the preparation of yellow ink E is yellow pigment C.I. I. 480.0 parts of PY74 I. A pigment dispersion S was obtained in the same manner except that PB15: 3 was changed to 480 parts.
After the pigment dispersion S was diluted with ultrapure water so as to have a pigment concentration of 0.1%, the volume average particle size determined by the dynamic light scattering method was 68.3 nm (TEM average particle size: 40.8 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersibility, was 1.72.
The pigment dispersion S and the resin emulsion shown in Table 1 were combined to produce a cyan ink S having the ink composition shown in Table 3. Thereafter, the ink was diluted 500 times with ultrapure water, and the dynamic light scattering method was used. The obtained volume average particle diameter (TEM average particle diameter), volume average particle diameter Mv / number average particle diameter Mn were measured.

(Preparation of black ink T)
After mixing 30 parts of carbon black “MA-100” (pH 3.5, manufactured by Mitsubishi Kasei Co., Ltd.) well with 100 parts of ion-exchanged water, 50 parts of sodium hypochlorite (effective chlorine concentration: 12%) was added dropwise thereto. And stirred at 100 to 105 ° C. for 12 hours. The obtained dispersion stock solution was designated as Toyo Filter Paper No. The mixture was filtered through 2 (manufactured by Advantis) and washed with water until the pigment particles leaked. This pigment wet cake was redispersed in 300 parts of water, and desalted with a reverse osmosis membrane to an electric conductivity of 2 mS / cm. Further, this pigment dispersion (pH = 8 to 10) was concentrated to a pigment concentration of 10% using an evaporator to obtain a pigment dispersion T containing carbon black subjected to surface treatment.
After the pigment dispersion T was diluted with ultrapure water so as to have a pigment concentration of 0.1%, the volume average particle size determined by the dynamic light scattering method was 130.1 nm (TEM average particle size: 75.2 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersity, was 1.74.
A black ink T having the ink composition shown in Table 3 was prepared by combining the pigment dispersion T and the resin emulsion shown in Table 1. Thereafter, the ink was diluted 1000 times with ultrapure water, and a dynamic light scattering method was used. The obtained volume average particle diameter (TEM average particle diameter), volume average particle diameter Mv / number average particle diameter Mn were measured.

(Preparation of black ink U)
Carbon black “S170” (Evonik Degussa Japan Co., Ltd.) 10 parts, water-soluble resin dispersant “John Krill J62” (Johnson Polymer Co., Ltd.) 15 parts, sodium hydroxide 0.6 parts, water 25 parts are mixed, and zirconia Dispersed for 10 hours in a ball mill with beads. The obtained pigment dispersion was filtered through glass fiber filter paper GA-100 (manufactured by Advantech Toyo Co., Ltd.) and further washed with water. This pigment wet cake was redispersed in 500 parts of water, and desalted with a reverse osmosis membrane to an electric conductivity of 2 mS / cm. Furthermore, the pigment dispersion liquid U which concentrated and adjusted so that the pigment density | concentration might be 15 weight% using an evaporator, and disperse | distributed carbon black using the polymer dispersing agent was obtained.
After the pigment dispersion U was diluted with ultrapure water so as to have a pigment concentration of 0.1%, the volume average particle size determined by the dynamic light scattering method was 119.3 nm (TEM average particle size: 67.1 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersity, was 1.75.
This pigment dispersion U and the resin emulsion shown in Table 1 are combined to produce a black ink U having the ink composition shown in Table 3. Thereafter, the ink is diluted 1000 times with ultrapure water, and the dynamic light scattering method is used. The obtained volume average particle diameter (TEM average particle diameter), volume average particle diameter Mv / number average particle diameter Mn were measured.

(Preparation of black ink V)
In the preparation of yellow ink E, the yellow pigment C.I. I. A pigment dispersion V was obtained in the same manner except that 480.0 parts of PY74 were changed to 480 parts of carbon black “S170” (Evonik Degussa Japan).
After the pigment dispersion V was diluted with ultrapure water so that the pigment concentration became 0.1%, the volume average particle size determined by the dynamic light scattering method was 68.5 nm (TEM average particle size: 42.4 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersibility, was 1.61.
This pigment dispersion U and the resin emulsion shown in Table 1 are combined to produce a black ink U having the ink composition shown in Table 3. Thereafter, the ink is diluted 1000 times with ultrapure water, and the dynamic light scattering method is used. The obtained volume average particle diameter (TEM average particle diameter), volume average particle diameter Mv / number average particle diameter Mn were measured.

(Preparation of black inks W-1 to W-3)
In the preparation of the pigment dispersion E, the yellow pigment C.I. I. A pigment dispersion was obtained in the same manner except that 480.0 parts of PY74 were changed to 480 parts of carbon black “S170” (Evonik Degussa Japan). The supernatant obtained by centrifuging this pigment dispersion at 20000 rpm for 30 minutes with a centrifugal separator is concentrated and adjusted using an evaporator so that the pigment concentration becomes 10%. Obtained.
After the pigment dispersion W was diluted with ultrapure water so as to have a pigment concentration of 0.1%, the volume average particle size determined by the dynamic light scattering method was 38.3 nm (TEM average particle size: 24.3 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersibility, was 1.50.
This pigment dispersion W and the resin emulsion shown in Table 1 were combined to produce black inks W-1 to W-3 having the ink composition shown in Table 3, and then the ink was diluted 500 times with ultrapure water, The volume average particle diameter (TEM average particle diameter) and volume average particle diameter Mv / number average particle diameter Mn determined by the dynamic light scattering method were measured.

Abbreviations of components used in the present invention will be described below.
DEGmBE: diethylene glycol monobutyl ether TEGmBE: triethylene glycol monobutyl ether PGmBE: polyethylene glycol monobutyl ether DPGmBE: dipropylene glycol monobutyl ether 1,2-HD: 1,2-hexanediol

[Evaluation 1]
(Evaluation of ink)
For each ink shown in Table 4, using an inkjet printer EM930C printer (manufactured by Seiko Epson Corporation), the optical density (OD) of plain paper that is a non-glossy medium and the glossiness of glossy paper that is a glossy medium. evaluated.
The optical density (OD) of plain paper was Xerox 4024 paper (manufactured by Xerox, USA) as plain paper and printed in a photo 720 dpi print mode.
The glossiness of glossy paper, which is a glossy medium, was obtained by using PM photographic paper (manufactured by Seiko Epson Corporation) as the glossy paper and printing in a photo 1440 dpi printing mode.

(Measurement of optical density (OD))
About the said sample printed on the plain paper, the optical density (OD) measurement was performed using GRETAG MACBETH SPECTROSCAN SPM-50 (made by GRETAG (USA)). Table 4 shows the measurement results.

(Evaluation of glossiness of glossy paper)
The glossiness of the above sample printed on glossy paper was measured. The specular glossiness of the recording surface at an incident angle of 60 degrees was measured with a gloss checker IG-320 (manufactured by Horiba Seisakusho), and an average of 5 times was taken for each recording paper. Table 4 shows the measurement results.

(Eraser friction test)
The sample printed on the glossy paper obtained above was rubbed 10 times with a weight of 750 g applied to a commercially available eraser, and the peeled state of the image before and after the friction was visually observed. Evaluation was performed according to the following evaluation criteria. The evaluation results are shown in Table 4.
-Evaluation criteria-
3: No peeling.
2: Slight peeling is observed.
1: Partial peeling was observed and visibility was also lowered.

As can be seen from Table 4, it can be seen that the sample (printed material) obtained using each ink satisfying the requirements of the present invention has excellent optical density and high gloss.
Further, it can be seen that each ink satisfying the requirements of the present invention is excellent in abrasion resistance from the result of the eraser friction test. In addition, since the cyan ink Q-4 was better than the cyan ink Q-2, the dispersant (component derived from an anionic group) contained in the ink was water-insoluble colorant particles and emulsion. It is presumed that the image was fixed with the particles more uniformly dispersed.

[Examples 1-14, Comparative Examples 1-5]
[Preparation of ink set]
Using each of the yellow, magenta, cyan, and black inks obtained above, an ink set was prepared in combination as shown in Table 5 below. Incidentally, the in each ink, the ink weight of duty of 100% was 14~16mg / inch ^2.

[Evaluation 2]
(Evaluation of color reproducibility)
Using an ink jet printer (trade name “MC-2000”, manufactured by Seiko Epson Corporation), the ink set (black ink) shown in Table 5 was used on a recording medium (trade name “PM Photo Paper”, manufactured by Seiko Epson Corporation). Were printed at 100% duty at 1440 × 720 dpi to obtain a printed matter.
“Duty” is defined by the following formula (A) and indicates a unit of the calculated value D. 100% duty means the maximum ink weight of a single color for a pixel.
Formula (A)
D = (actual printing dot number / (vertical resolution × horizontal resolution)) × 100 (duty)

The optical density (OD) of each printed matter thus obtained was measured with a light source D65 and a viewing angle of 2 degrees using “SPM-50” manufactured by Gretag, and defined in the CIELAB color space for each printed matter. L ^* , a ^* and b ^* values were determined.

  Evaluation color: 100% duty formed by one color ink selected from yellow, magenta, and cyan ink and 100% duty formed by 50% duty of each of two colors ink selected from yellow, magenta, and cyan ink Duty color mixture.

The area including the origin of the graph drawn by the a ^* value and b ^* value of the evaluation color in each printed matter (the area surrounded by the a ^* value, the b ^* value, and the origin) was determined, and this was used as the saturation area. . The results are shown in Table 5. The larger the saturation area value, the wider the color reproduction range of the ink set.

(Texture evaluation of printed materials)
Using each ink set shown in Table 5, the ink jet printer PM900C (manufactured by Seiko Epson Corporation) was used for a recording medium (trade name “PM Photo Paper”, manufactured by Seiko Epson Corporation) with a duty of 10 to 100% ( In the case of a single color), printing was performed at 10 to 120% (when a plurality of inks were arbitrarily mixed).
At the time of printing, when forming a mixed color portion of a secondary color or higher, the mixed color portion was formed by at least two of yellow, magenta, and cyan inks. Further, in this case, each ink was used in the above-described preferred combination according to the range of a ^* and b ^* described below. Specifically, when a ^* and b ^* form a mixed color portion where a ^* = about −50 to about 50 and b ^* = about −50 to about 50, respectively, yellow, magenta, A picture image of the Japanese Standards Association SCID sample “bicycle” was printed at 1440 × 720 dpi using cyan ink and black ink.

The color tone and balance of the printed matter thus obtained were visually evaluated. The evaluation criteria are as follows. The results are shown in Table 5.
-Evaluation criteria-
A: The color tone change from the high-density part of yellowish color to the light-density part in the printed material is smooth, the density of the entire printed material is high, and the color tone is smooth.
B: The yellowish high density part in the printed matter is slightly conspicuous, and the yellowness is slightly felt in the high density part of the red and green hues.
C: The yellowness in the printed material is conspicuous, and the density of the blue hue feels light.
D: The density of yellowishness in the printed matter is slightly felt, and a change in color is felt in the hues of green and red.

(Evaluation of glossiness)
The degree of glossiness of the entire print portion in the print obtained in the texture evaluation of the print was visually observed and evaluated according to the following criteria. The evaluation results are shown in Table 5.
-Evaluation criteria-
3: High glossiness.
2: There is glossiness.
1: A glossy feeling is not recognized.

(Evaluation of abrasion resistance by eraser friction test)
Each print obtained in the texture evaluation of the print was rubbed 10 times with a commercial eraser under a load of 750 g, and the peeled state of the image before and after the friction was observed. Evaluation was performed according to the following criteria. The evaluation results are shown in Table 5.
-Evaluation criteria-
3: No peeling.
2: Slight peeling is observed.
1: Partial peeling was observed and visibility was also lowered.

(Evaluation of ejection properties)
In the printed matter obtained in the texture evaluation of the printed matter, the printed portion was visually observed and evaluated according to the following criteria. The evaluation was performed on a portion printed at a high duty. The evaluation results are shown in Table 5.

-Evaluation criteria-
A: The ink does not get on the printed part, and the fine part where the color of the paper fabric appears is not seen at all.
B: Although a minute portion in which the color of the paper fabric appears without the IN on the printed portion is slightly recognized, it is practically acceptable.
C: A minute portion in which the color of the paper fabric appears without ink on the printed portion can be seen.

As is clear from the results shown in Table 5, it can be seen that the ink sets of Examples 1 to 14 have a large saturation area calculated by color measurement and are excellent in color reproducibility. Further, it can be seen that in a printed matter (picture image) printed in full color, the printing density is high, the color tone balance of the whole printed matter is good, and the abrasion resistance is also excellent.
In addition, since the entire printed matter (picture image) has a glossy feeling and excellent ejection properties, a high-quality and high-quality printed matter can be provided.

In addition, the printed matter printed using the ink set of Example 4 had vivid red and blue hues, and had a good color balance (texture). Further, it was found that the printed matter printed using the ink set of Example 6 had a good color tone from yellowish green to green, and a printed matter having a good color tone was obtained.
Furthermore, it was found that the prints using the ink sets of Examples 1 to 7 and 9 to 13 were excellent in blackening.

[Production of special color ink]
(Preparation of special color inks X-1, X-2, X-3)
In preparing the pigment dispersion J, C.I. I. Instead of 10 parts of PR122 quinacridone pigment, C.I. I. A pigment dispersion X having a pigment content of 10% containing pigment-containing particles was obtained in the same manner except that the PV23 was changed to 10 parts.
After the pigment dispersion X was diluted with ultrapure water so that the pigment concentration was 0.1%, the volume average particle size determined by the dynamic light scattering method was 28.5 nm (TEM average particle size: 23.3 nm). The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersibility, was 1.16. The calculated polydispersity index (PDI) was 1.18, no change was observed in the particle size after storage for 2 weeks, no sediment was observed, and no discoloration was observed.

  To 20.0 parts of pigment dispersion X having a pigment concentration of 10%, 15.0 parts of glycerin, 5.0 parts of ethylene glycol, 2.0 parts of 2-pyrrolidone, 5.0 parts of 1,2-hexanediol, and Olphine E1010 0.5 parts and ion-exchanged water were added so that the pigment concentration was 4.0% with respect to the total amount of the ink, thereby producing a special color ink X-1. Thereafter, the ink was diluted 40 times with ultrapure water, and the volume average particle size determined by the dynamic light scattering method was 28.9 nm (TEM average particle size: 23.8 nm), volume average particle size Mv / number average. The ratio of particle size Mn was 1.18.

  Similarly, 15.0 parts of glycerin, 5.0 parts of ethylene glycol, 2.0 parts of 2-pyrrolidone, 5.0 parts of 1,2-hexanediol, orufine are added to 20.0 parts of pigment dispersion X having a pigment concentration of 10% 0.5 parts of E1010, 4 parts of emulsion (v) shown in Table 1 as emulsion solid content%, and ion-exchanged water were added so that the pigment content was 4.0% with respect to the total amount of ink. -2 was produced. Thereafter, the ink was diluted 40 times with ultrapure water, and the volume average particle size determined by the dynamic light scattering method was 26.8 nm (TEM average particle size: 23.7 nm), volume average particle size Mv / number average. The ratio of particle size Mn was 1.17.

  Similarly, 15.0 parts of glycerin, 5.0 parts of ethylene glycol, 2.0 parts of 2-pyrrolidone, 5.0 parts of 1,2-hexanediol, orufine are added to 20.0 parts of pigment dispersion X having a pigment concentration of 10% 0.5 parts of E1010, 4 parts of emulsion (iv) shown in Table 1 as emulsion solid content%, and ion-exchanged water were added so that the pigment content was 4.0% with respect to the total amount of ink. -3 was produced. Thereafter, the ink was diluted 40 times with ultrapure water, and the volume average particle size determined by the dynamic light scattering method was 35.1 nm (TEM average particle size: 23.9 nm), volume average particle size Mv / number average. The ratio of particle size Mn was 1.44.

(Preparation of special color ink Y)
In the preparation of yellow ink E, the yellow pigment C.I. I. 480.0 parts of PY74 I. A pigment dispersion Y was obtained in the same manner except that the pigment orange was changed to 480 parts.
To 13.3 parts of this pigment dispersion Y, 15.0 parts of glycerin, 5.0 parts of ethylene glycol, 2.0 parts of 2-pyrrolidone, 5.0 parts of 1,2-hexanediol, 0.5 part of Olfine E1010, Then, ion-exchanged water was added so that the pigment concentration was 2.0% with respect to the total amount of the ink, and a special color ink Y was produced.
After this special color ink Y was diluted 400 times with ultrapure water, the volume average particle size determined by the dynamic light scattering method was 81.6 nm (TEM average particle size: 51.0 nm), and it was an index of monodispersity. The volume average particle diameter Mv / number average particle diameter Mn ratio was 1.61. The calculated polydispersity index (PDI) was 2.28.

(Preparation of special color inks Z-1, Z-2, Z-3)
In preparing the pigment dispersion J, C.I. I. Instead of 10 parts of PR122 quinacridone pigment, C.I. I. A pigment dispersion Z having a pigment concentration of 10% containing pigment-containing particles was obtained in the same manner except that PR254 was changed to 10 parts.
After this pigment dispersion Z was diluted with ultrapure water to a pigment content of 0.1%, the volume average particle size determined by the dynamic light scattering method was 25.5 nm (TEM average particle size: 21.2 nm), The ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersibility, was 1.20. The calculated polydispersity index (PDI) was 1.21, no change was observed in the particle size after storage for 2 weeks, no sediment was observed, and no discoloration was observed.

  To 20.0 parts of this pigment dispersion Z having a pigment concentration of 10%, 15.0 parts of glycerin, 5.0 parts of ethylene glycol, 2.0 parts of 2-pyrrolidone, 5.0 parts of 1,2-hexanediol and Olphine E1010 0.5 parts and ion-exchanged water were added so that the pigment concentration was 4.0% with respect to the total amount of the ink, thereby producing a special color ink Z-1. Thereafter, the ink was diluted 40 times with ultrapure water, and the volume average particle diameter determined by the dynamic light scattering method was 26.1 nm (TEM average particle diameter: 21.5 nm), volume average particle diameter Mv / number average. The ratio of the particle size Mn was 1.21.

  In the same manner as described above, 15.0 parts of glycerin, 5.0 parts of ethylene glycol, 2.0 parts of 2-pyrrolidone, 5.0 parts of 1,2-hexanediol were added to 20.0 parts of pigment dispersion Z having a pigment concentration of 10%. In addition, 0.5 part of Olfine E1010, 4 parts of emulsion (ii) shown in Table 1 as emulsion solid content%, and ion exchange water were added so that the pigment concentration was 4.0% with respect to the total amount of ink. Ink Z-2 was produced. Thereafter, the ink was diluted 40 times with ultrapure water, and the volume average particle diameter determined by the dynamic light scattering method was 24.8 nm (TEM average particle diameter: 21.4 nm), volume average particle diameter Mv / number average. The ratio of particle size Mn was 1.17.

  In the same manner as described above, 15.0 parts of glycerin, 5.0 parts of ethylene glycol, 2.0 parts of 2-pyrrolidone, 5.0 parts of 1,2-hexanediol were added to 20.0 parts of pigment dispersion Z having a pigment concentration of 10%. In addition, 0.5 part of Olfine E1010, 4 parts of the emulsion (iv) shown in Table 1 in% of emulsion solid content, and ion-exchanged water were added so that the pigment content was 4.0% with respect to the total amount of ink. Ink Z-3 was produced. Thereafter, the ink was diluted 40 times with ultrapure water, and the volume average particle size determined by the dynamic light scattering method was 35.6 nm (TEM average particle size: 21.9 nm), volume average particle size Mv / number average. The ratio of particle size Mn was 1.61.

[Evaluation 3]
(Evaluation of special color ink)
Using the special color inks X1 to X-3 and the special color inks Z-1 to Z-3 obtained as described above, the optical density (OD) of plain paper as a non-glossy medium and glossy paper as a glossy medium The glossiness was evaluated. Note that Xerox 4024 paper (manufactured by Xerox, USA) was used as plain paper, and PM photo paper (manufactured by Seiko Epson Corporation) was used as glossy paper. The printer used was an ink jet printer EM930C manufactured by Seiko Epson Corporation, and evaluation was performed using a sample printed in a printing mode of 720 dpi for plain paper and 1440 dpi for glossy paper. The measurement apparatus and measurement conditions were the same as in Evaluation 1. The results are shown in Table 6.

  As can be seen from Table 6, samples using spot color inks X-2 and Z-2 have excellent optical density and high gloss. Moreover, it turns out that it is excellent in abrasion resistance from the result of an eraser friction test.

[Examples 15 to 18]
[Preparation of ink set containing special color ink]
Ion exchange water was added to each of the special color inks X1 to X-3, the special color ink Y, and the special color inks Z-1 to Z-3 obtained above so that the pigment concentration was 2.0%. Ink sets were prepared in combination as shown in Table 7 below. Incidentally, the in each ink, the ink weight of duty of 100% was 14~16mg / inch ^2.

[Evaluation 4]
(Evaluation of color reproducibility)
As in Evaluation 2, using an inkjet printer (trade name “MC-2000”, manufactured by Seiko Epson Corporation), a recording medium (trade name “PM Photo Paper”, manufactured by Seiko Epson Corporation) 100% duty was printed at 1440 × 720 dpi using each of the ink sets shown in FIG. 7 except for the black ink to obtain a printed matter.

The optical density (OD) of each of the obtained printed materials was measured with a light source D65 and a viewing angle of 2 degrees using “SPM-50” manufactured by Gretag Co., and L ^* defined in the CIELAB color space for each printed material, The a ^* and b ^* values were determined.

Evaluation color:
100% duty single color formed with one color ink, one of yellow ink and special color ink Y or special color inks Z1 to Z3, one of magenta ink and special color ink Y or special color inks Z1 to Z3 In combination inks of special color ink and cyan ink, cyan ink and yellow ink, such as any one of magenta ink and special color inks X-1 to X3, each ink is formed at 50% duty. 100% duty color mixture.

In the same manner as in Evaluation 2, the area on the side including the origin of the graph drawn by the a ^* value and b ^* value of the evaluation color in each printed matter was obtained, and this was used as the saturation area. The results are shown in Table 7.

(Texture evaluation of printed materials)
Using each ink set shown in Table 7, the ink jet printer PM900C (manufactured by Seiko Epson Corporation) was used for a recording medium (trade name “PM Photo Paper”, manufactured by Seiko Epson Corporation) with a duty of 10 to 100% (single color). ) And 10 to 120% (when a plurality of inks are arbitrarily mixed).
At the time of printing, when forming a mixed color portion of a secondary color or higher, the mixed color portion was formed by at least two kinds of yellow, magenta, and cyan inks and the special color inks X1 to X3, Y, and Z1 to Z3.
Further, in this case, each ink was used in the above-described preferred combination according to the range of a ^* and b ^* described below.
Specifically, when a ^* and b ^* form a mixed color portion where a ^* = about −50 to about 50 and b ^* = about −50 to about 50, respectively, yellow, magenta, A picture image of the Japanese Standards Association SCID sample “bicycle” was printed at 1440 × 720 dpi, using cyan and cyan inks, special color inks X1 to X3, Y and Z1 to Z3, and black ink.

  The color tone / balance and glossiness of the printed matter obtained in the same manner as in Evaluation 2 were evaluated by visual evaluation and an eraser friction test. The results are shown in Table 7.

  As can be seen from the results shown in Table 7, when the ink sets of Examples 15 to 18 were used, a wider saturation was obtained as compared with the case of printing with CMYK (cyan, magenta, yellow, black) process colors. It can be seen that the area can be obtained and the color reproducibility is very excellent. Further, it can be seen that even in a printed matter printed with full color using special color ink, the printing density is high, the color tone balance of the whole printed matter is good, and the abrasion resistance is excellent.

  In addition, streaks and unevenness were not observed for the printed matter printed using the ink set shown in Table 7, and it was found that the discharge property was excellent.

(X-ray diffraction measurement)
RINT2500 manufactured by Rigaku Corporation was used for the following X-ray diffraction measurement. The X-ray diffraction measurement was performed using a Cu-Kα1 line using a copper target.

The magenta pigment dispersion J and the magenta pigment dispersion L prepared above were dried using an evaporator to form powders, and X-ray diffraction measurement was performed using RINT2500 manufactured by Rigaku Corporation. When the respective crystallite diameters were calculated from the obtained spectra, the pigment dispersion J had a crystallite diameter of 180 ± 20 mm in the dispersion, and the pigment dispersion L had a spectrum of 2θ = 4 deg to A halo was observed at 70 deg.
Similarly, when magenta pigment dispersions K, M, N, and O, cyan pigment dispersions Q and R, black pigment dispersion W, and special color pigment dispersions X and Z were measured by X-ray diffraction, crystals were obtained. The child diameters were 105 ± 20 mm, 202 ± 20 mm, 216 ± 20 mm, 233 ± 20 mm, 197 ± 20 mm, 222 ± 20 mm, 165 ± 20 mm, 163 ± 20 mm, and 157 ± 20 mm, respectively.
From this result, the pigment fine particles contained in the magenta inks J, K, M, N, O, cyan inks Q and R, black ink W, special color inks X1 to X3, and special color inks Z1 to Z3 have a crystal structure. I guess that.

[Other evaluations]
Each printed matter obtained above was set in a fading tester, and a xenon lamp was irradiated with an illuminance of 170,000 lux for 4 days to perform a light resistance test. Compared with other examples not using the magenta ink L, the printed matter printed using the ink set containing the magenta ink L was visually perceived to have a slight color change including magenta. The printed matter printed using the ink set of another example not using the magenta ink L was excellent in color tone and balance of the printed matter.

Claims (10)

  In an ink set including cyan ink, yellow ink, and magenta ink, the water-insoluble colorant particles contained in the yellow ink have a dispersion average particle diameter of 60 to 200 nm and are contained in at least one of the inks different from the yellow ink. An ink set comprising a resin emulsion in which a water-insoluble colorant particle has a dispersion average particle diameter of 5 to 50 nm and a resin emulsion particle has a dispersion average particle diameter of 1 to 50 nm.   The ink set according to claim 1, wherein the water-insoluble colorant particles contained in at least one of the inks different from the yellow ink have a crystal structure. The polydispersity index (PDI) represented by the following formula (1) of water-insoluble colorant particles contained in at least one of the inks different from the yellow ink is 2 or less. Ink set.
Formula (1)
PDI = (D ₉₀ -D ₁₀ ) / D ₅₀
[In the formula, D ₉₀ , D ₅₀ , and D ₁₀ are integrals of the distribution function dG = F (D) dD (G is the number of pigment particles, D is the particle size), respectively, which is 0.9 of the total number of pigment particles. It represents a particle size equal to (90 number%), 0.5 (50 number%) and 0.1 (10 number%). ]   A compound in which at least one of the inks different from the yellow ink contains a dispersant, and the dispersant has one or more hydrophilic groups selected from a carboxylic acid group, a sulfone group, a phosphoric acid group, a hydroxyl group, and an ethylene oxide group The ink set according to any one of claims 1 to 3.   The ink set according to any one of claims 1 to 4, wherein the yellow ink contains a resin emulsion having a dispersion average particle diameter of 1 to 60 nm.   The water-insoluble colorant particles contained in the yellow ink are C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 110, pigment yellow 138, C.I. I. Pigment yellow 151, and C.I. I. The ink set according to any one of claims 1 to 5, comprising one or more pigments selected from CI Pigment Yellow 155.   The water-insoluble colorant particles contained in the magenta ink are C.I. I. Pigment red 122, C.I. I. Pigment red 202, C.I. I. Pigment red 254, and C.I. I. The ink set according to claim 1, comprising one or more pigments selected from CI pigment violet 19.   The ink set according to any one of claims 1 to 7, wherein the water-insoluble colorant particles contained in the cyan ink contain a copper phthalocyanine pigment.   The inkjet recording method using the ink set of any one of Claims 1-8.   A printed matter recorded using the ink set according to any one of claims 1 to 9.