JP2018080313A - Ink, recording method, and recording apparatus - Google Patents

Abstract

Kind Code: A1 Abstract: To provide an ink capable of suppressing a decrease in whiteness and maintaining sedimentation even when heated and when an organic solvent having a low SP value is used. SOLUTION: An IR spectrum of hollow resin particles containing a copolymer having structural units represented by structural formulas (1) and (2), an organic solvent, and water. , the peak ratio of the maximum values of the peaks at 1,600 cm −1 ± 10 cm −1 and 1,730 cm −1 ± 10 cm −1 is 3.0 to 6.0, and the mixed SP value of the organic solvent is 11.0 to 15.5 (cal/cm3) 1/2 ink. [Selection figure] None

Description

  The present invention relates to an ink, a recording method, and a recording apparatus.

  As a white color material for ink-jet white ink, a system using titanium dioxide is generally used. An ink using hollow resin particles having a hollow inner layer as a white color material is also known.

The hollow resin particles exhibit whiteness by utilizing the difference in refractive index between the inner layer and the outer shell resin. For example, an ink composition that includes hollow resin particles and at least one transparency inhibitor selected from hexylene glycol and trimethylolpropane has been proposed (see, for example, Patent Document 1).
In addition, multi-mode inks in which the hollow resin particles have different particle sizes of at least 0.1 μm have been proposed (for example, see Patent Document 2).

  An object of the present invention is to provide an ink capable of suppressing a decrease in whiteness and maintaining a sedimentation degree even when heated and when an organic solvent having a low SP value is used.

The ink of the present invention as means for solving the above problems is a hollow containing a structural unit represented by the following structural formula (1) and a copolymer having a structural unit represented by the following structural formula (2). containing resin particles, and an organic solvent, and water, in the IR spectrum of the hollow resin particles, and the maximum value of the peak at 1,600cm ^-1 ± 10cm ^-1 and X, 1,730cm ^-1 ± 10cm ^-1 The peak ratio (Y / X) when the maximum peak value in Y is Y is 3.0 or more and 6.0 or less, and the mixed SP value of the organic solvent is 11.0 (cal / cm ³ ) ^{0 .5} least 15.5 (cal ^/ cm ³⁾ is ^0.5 or less.

  According to the present invention, it is possible to provide an ink capable of suppressing a decrease in whiteness and maintaining a sedimentation degree even when heated and when an organic solvent having a low SP value is used.

FIG. 1 is an explanatory perspective view illustrating an example of an ink jet recording apparatus. FIG. 2 is an explanatory perspective view showing an example of a main tank in the ink jet recording apparatus.

(ink)
The ink of the present invention comprises a structural unit represented by the following structural formula (1), a hollow resin particle comprising a copolymer having a structural unit represented by the following structural formula (2), an organic solvent, water, containing, in the IR spectrum of the hollow resin particles, the maximum value of the peak at 1,600cm ^-1 ± 10cm ^-1 and X, when the maximum value of the peak at 1,730cm ^-1 ± 10cm ^-1 and the Y The peak ratio (Y / X) is 3.0 or more and 6.0 or less, and the mixed SP value of the organic solvent is 11.0 (cal / cm ³ ) ^0.5 or more and 15.5 (cal / cm). ³ ) ^0.5 or less, preferably containing a wax, and further containing other coloring materials, resins, and additives as necessary.
In the ink of the present invention, when the ink using the conventional hollow resin particles is heated or the organic solvent having a low SP value is contained in the ink, the resin dissolves and the hollow resin particles are crushed. This is based on the knowledge that there is a problem that the lightness L ^* is lowered and the whiteness is lowered, and that the hollow resin particles are crushed so that only the hollow resin particles are floated in the ink.

<Hollow resin particles>
The hollow resin particles include a copolymer having a structural unit represented by the structural formula (1) and a structural unit represented by the structural formula (2).

The hollow resin particles are white and have excellent opacity due to light scattering due to the difference in refractive index between the air layer inside the dried particles and the polymer layer of the shell.
When the copolymer contains a structural unit represented by the structural formula (1), the lightness L ^* of the ink itself can be improved. Moreover, since the said copolymer contains the structural unit represented by the said Structural formula (2), the intensity | strength of a hollow resin particle can be improved and it suppresses that a hollow resin particle is crushed, Hunter whiteness Can be improved.

Wherein in the IR spectrum of the hollow resin particles, 1,600cm ^-1 the maximum value of the peak at ± 10 cm ^-1 and X, the peak ratio when the maximum value of the peak at 1,730cm ^-1 ± 10cm ^-1 was Y ( Y / X) is 3.0 or more and 6.0 or less, and preferably 3.0 or more and 5.5 or less.
The peak ratio (Y / X) is the ratio of the structural unit represented by the structural formula (1) and the structural unit represented by the structural formula (2) in the hollow resin particles (the structural formula (2) The structural unit represented by the structural unit represented by the structural formula (1)).
This occurs because the infrared absorption at 1,600 cm ⁻¹ is derived from the C═C stretching vibration of the aromatic ring contained in the structural unit represented by the structural formula (1), and 1,730 cm ^−1. This is because the infrared absorption in is caused by the stretching vibration of the carbonyl group C═O contained in the structural unit represented by the structural formula (2).

  When the peak ratio (Y / X) is 3.0 or more, the ratio of the structural unit represented by the structural formula (2) in the copolymer of the hollow resin particles is increased, and the hollow resin particles Therefore, the decrease in the Hunter whiteness caused by the dissolution of the resin of the hollow resin particles by energy such as heat can be suppressed. Further, when the peak ratio (Y / X) is 6.0 or less, the structural unit represented by the structural formula (1) in the copolymer and the structure represented by the structural formula (2) It is possible to balance the units, to prevent the hollow resin particles from being crushed, and to improve the Hunter whiteness. Moreover, the problem that only the hollow resin particles float in the ink can be improved, and the sedimentation degree can be maintained.

The ratio of the structural unit represented by the structural formula (1) and the structural unit represented by the structural formula (2) in the hollow resin particles is the same as the structural unit represented by the structural formula (1) in the ink and The ratio of the structural unit represented by the structural formula (2) is almost the same.
Ratio of the structural unit represented by the structural formula (1) and the structural unit represented by the structural formula (2) in the ink (the structural unit represented by the structural formula (2) / the structural formula (1) Is preferably 3.0 or more and 6.0 or less.

As said hollow resin particle, what was synthesize | combined suitably may be used and a commercial item may be used.
The method for synthesizing the hollow resin particles is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a vinyl monomer, a surfactant, a polymerization initiator, and an aqueous dispersion medium are heated in a nitrogen atmosphere. A so-called emulsion polymerization method in which a hollow resin particle emulsion is formed by stirring while stirring is preferred.

  Examples of the vinyl monomer include nonionic monofunctional ethylenically unsaturated monomers, bifunctional vinyl monomers, trifunctional or higher functional vinyl monomers, and the like. These may be used alone or in combination of two or more.

  Examples of the nonionic monofunctional ethylenically unsaturated monomer include styrene, vinyl toluene, ethylene, vinyl acetate, vinyl chloride, vinylidene chloride, acrylonitrile, (meth) acrylamide, (meth) acrylic acid ester, and the like. These may be used alone or in combination of two or more. Among these, (meth) acrylic acid ester is preferable.

  Examples of the (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and benzyl (meth) ) Acrylate, lauryl (meth) acrylate, oleyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like.

  Examples of the bifunctional vinyl monomer include divinylbenzene, allyl (meth) acrylate, ethylene glycol di (meth) acrylate, 1,5-butanediol di (meth) acrylate, diethylene glycol di (meth) acrylate, and the like. .

  Examples of the trifunctional or higher vinyl monomer include trimethylolpropane tri (meth) acrylate.

  By copolymerizing the nonionic monofunctional ethylenically unsaturated monomer with at least one of the bifunctional vinyl monomer and the trifunctional or higher vinyl monomer to highly crosslink, not only light scattering characteristics but also heat resistance Hollow resin particles having properties such as property, solvent resistance and solvent dispersibility can be obtained.

  The surfactant is not particularly limited as long as it forms a molecular aggregate such as micelles in water. For example, an anionic surfactant, a nonionic surfactant, a cationic surfactant, an amphoteric surfactant, etc. Is mentioned. These may be used alone or in combination of two or more.

  As the polymerization initiator, a known compound soluble in water can be used, and examples thereof include hydrogen peroxide and potassium persulfate. These may be used alone or in combination of two or more.

  Examples of the aqueous dispersion medium include water and water containing a hydrophilic organic solvent.

  Examples of commercially available hollow resin particles include ROPAQUE ULTRA E (peak ratio (Y / X) = 1.5), DUAL, OP-62 manufactured by Dow Chemical Co., Ltd., Cybinol series manufactured by Seiden Chemical Co., Ltd. Examples include the SX series manufactured by JSR Corporation. These may be used alone or in combination of two or more.

There is no restriction | limiting in particular as a hollow rate of the said hollow resin particle, Although it can select suitably according to the objective, 20% or more and 80% or less are preferable, and 35% or more and 70% or less are more preferable. If the hollow ratio is 20% or more, the Hunter whiteness of the printed image can be improved, and if it is 80% or less, the particle diameter of the hollow resin particles can be kept small. Sedimentation can be suppressed.
Examples of the measurement of the hollow ratio include a method using a scanning electron microscope (SEM). In addition, the said hollow rate is ratio of the volume when it approximates with a spherical body from the outer diameter and inner diameter (diameter of a hollow part) of the said hollow resin particle, and can be represented by following formula (1).
Hollow ratio (%) = (internal volume of hollow resin particles / volume of hollow resin particles) × 100 (1)
Internal volume of hollow resin particles = 4π / 3 × (inner diameter of hollow resin particles) ³
Volume of hollow resin particles = 4π / 3 × (outer diameter of hollow resin particles) ³

The 50% cumulative volume particle size of the hollow resin particles is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 400 nm or more and 600 nm or less. When the 50% cumulative volume particle size is 400 nm or more, lightness can be secured even for a recording medium such as fine paper. When the 50% cumulative volume particle size is 600 nm or less, the sedimentation degree and ejection stability are excellent.
The 50% cumulative volume particle size can be measured using, for example, a particle size analyzer (device name: Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

The hollow resin particles are those in which the inner layer is hollow and the outer layer is covered with a resin, and the particle outer diameter is preferably 0.1 μm or more and 1 μm or less, and the inner diameter is 0.04 μm or more and 0.8 μm or less. preferable.
Examples of the measurement of the particle diameter include a method using a laser scattering / diffraction type particle diameter measuring apparatus.

Since the hollow resin particles have a hollow inner layer, the specific gravity as an ink is around 1, and unlike the titanium dioxide, the hollow resin particles do not easily settle over time.
In order to avoid sedimentation over time, the average thickness of the outer layer of the hollow resin particles is preferably 10% or more and 20% or less with respect to the overall size of the hollow resin particles.

  There is no restriction | limiting in particular as content of the said hollow resin particle, Although it can select suitably according to the objective, 3.0 mass% or more and 14.0 mass% or less are preferable with respect to the ink whole quantity. 0 mass% or more and 12.5 mass% or less are more preferable. When the content is 5.0% by mass or more, Hunter whiteness can be secured even for a recording medium such as fine paper. When the content is 12.5% by mass, the sedimentation degree and the ejection stability are excellent.

<Organic solvent>
In the organic solvent, the mixed SP value calculated from the solubility parameter of the organic solvent alone excluding water in the ink (hereinafter referred to as SP value) is 11.0 (cal / cm ³ ) ^0.5 or more and 15. 5 (cal / cm ³ ) ^0.5 or less.
When the mixed SP value is 11.0 (cal / cm ³ ) ^0.5 or more, the difference from the SP value of the outer shell resin of the hollow resin particles becomes large. Therefore, the organic solvent contained in the ink Thus, dissolution of the outer shell resin of the hollow resin particles can be suppressed. If the mixed SP value is 15.5 (cal / cm ³ ) ^0.5 or less, the organic solvent is likely to volatilize and good drying properties can be obtained. it can.

The mixed SP value in the mixed solution of the organic solvent contained in the ink can be calculated from the following formula (2).
Mixed SP value (cal / cm ³ ) in a mixed solution of organic solvents in the ink ^0.5
= [SP value of organic solvent A x volume fraction of organic solvent A] + [SP value of organic solvent B x volume fraction of organic solvent B] + ... Formula (2)

  The SP value is a numerical value of how easily each other is melted. The SP value is represented by a square root of an attractive force between molecules, that is, a cohesive energy density (CED). The CED is the amount of energy required to evaporate 1 mL.

The SP value can be calculated using the following formula (3) by the Fedors method.
SP value (dissolution parameter) = (CED value) ^1/2 = (E / V) ^1/2 Formula (3)
In the above formula (3), E is the molecular aggregation energy (cal / mol), V is the molecular volume (cm ³ / mol), and when the evaporation energy of the atomic group is Δei and the molar volume is Δvi, the following formula ( 4) and the equation (5).
E = ΣΔei (4)
V = ΣΔvi Equation (5)
Although there are various theories on the calculation method of the SP value, the Fedors method generally used in the present invention is used.

As various data of the calculation method, the evaporation energy Δei and the molar volume Δvi of each atomic group, the data described in “Basic Theory of Adhesion” (written by Imoto Satoshi, published by Kobunshi Shuppankai, Chapter 5) can be used. it can.
For those in which —CF ₃ group or the like is not shown, R.I. F. Fedors, Polym. Eng. Sci. 14, 147 (1974).
For reference, when the SP value represented by the above formula (3) is converted to (J / cm ³ ) ^1/2 , 2.046 is converted to SI unit (J / m ³ ) ^1/2 . To do so, multiply by 2,046.

  In the present invention, the organic solvent includes those classified as functional penetrants and foam suppressors. In the present invention, only the organic solvent contained in the ink in an amount of 3% by mass or more is considered in the calculation of the SP value. When only one organic solvent is used, the SP value of the one organic solvent is set as the mixed SP value.

  Examples of the organic solvent include polyhydric alcohols, ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, sulfur-containing compounds, propylene carbonate, Examples include ethylene carbonate. These may be used individually by 1 type and may use 2 or more types together.

  Examples of the polyhydric alcohols include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, isoprene glycol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentane Diol, 2,4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol Glycerin, 1,2,6-hexanetriol, 2 Examples include ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl-1,3-pentanediol, and petriol. .

  Examples of the polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether. It is done.

  Examples of the polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

  Examples of the nitrogen-containing heterocyclic compound include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, γ- Examples include butyrolactone.

  Examples of the amides include formamide, N-methylformamide, N, N-dimethylformamide, 3-methoxy-N, N-dimethylpropionamide, 3-butoxy-N, N-dimethylpropionamide and the like.

  Examples of the amines include monoethanolamine, diethanolamine, and triethylamine.

  Examples of the sulfur-containing compound include dimethyl sulfoxide, sulfolane, thiodiethanol, and the like.

Among these, glycerin (SP value = 17.4 (cal / cm ³ ) ^0.5 , boiling point: 290 ° C.), 1,2-propanediol (SP value = 14.3 (cal / cm ³ ) ^0.5 , Boiling point: 178 ° C.), 1,3-propanediol (SP value = 15.5 (cal / cm ³ ) ^0.5 , boiling point: 188 ° C.), 1,2-butanediol (SP value = 13.1 ( cal / cm ³ ) ^0.5 , boiling point: 194 ° C., 1,3-butanediol (SP value = 14.2 (cal / cm ³ ) ^0.5 , boiling point: 208 ° C.), isoprene glycol (SP value = 12.1 (cal / cm ³ ) ^0.5 , boiling point: 203 ° C.) and oxetane compounds (SP value = 11.0 (cal / cm ³ ) ^0.5 , boiling point: 110 ° C.) are particularly preferable.
The organic solvent preferably has a boiling point of 250 ° C. or lower because it not only functions as a wetting agent but also provides good drying properties.

A polyol compound having 8 or more carbon atoms and a glycol ether compound are also preferably used. Specific examples of the polyol compound having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, and the like.
Specific examples of glycol ether compounds include polyhydric alcohol alkyls such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether. Examples of ethers include polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

  A polyol compound having 8 or more carbon atoms and a glycol ether compound can improve ink permeability when paper is used as a recording medium.

  The content of the organic solvent in the ink is not particularly limited and can be appropriately selected according to the purpose, but is preferably 10% by mass or more and 60% by mass or less from the viewpoint of the drying property and ejection reliability of the ink, 20 mass% or more and 60 mass% or less are more preferable.

<Water>
The water content in the ink is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10% by mass or more and 90% by mass or less, and 20% by mass from the viewpoint of ink drying property and ejection reliability. % To 60% by mass is more preferable.

<Color material>
The color material is not particularly limited, and pigments and dyes can be used.
An inorganic pigment or an organic pigment can be used as the pigment. These may be used alone or in combination of two or more. A mixed crystal may be used.
As the pigment, for example, a black pigment, a yellow pigment, a magenta pigment, a cyan pigment, a white pigment, a green pigment, an orange pigment, a glossy pigment such as gold or silver, a metallic pigment, or the like can be used.
Carbon black produced by known methods such as contact method, furnace method, thermal method in addition to titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow as inorganic pigments Can be used.
Organic pigments include azo pigments, polycyclic pigments (eg, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinofullerone pigments). Dye chelates (for example, basic dye type chelates, acidic dye type chelates), nitro pigments, nitroso pigments, aniline black, and the like can be used. Of these pigments, those having good affinity with the solvent are preferably used. In addition, resin hollow particles and inorganic hollow particles can also be used.
Specific examples of pigments include black for carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black, channel black, or copper, iron (CI pigment black 11). And metal pigments such as titanium oxide, and organic pigments such as aniline black (CI Pigment Black 1).
Further, for color use, C.I. I. Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104 , 108, 109, 110, 117, 120, 138, 150, 153, 155, 180, 185, 213, C.I. I. Pigment orange 5, 13, 16, 17, 36, 43, 51, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48: 2, 48: 2 (Permanent Red 2B (Ca)), 48: 3, 48: 4, 49: 1, 52: 2, 53: 1, 57: 1 (Brilliant Carmine 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81, 83, 88, 101 (Bengara), 104, 105, 106, 108 ( Cadmium red), 112, 114, 122 (quinacridone magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 184, 185, 190, 193, 202, 207, 208, 209, 213, 219, 224, 254, 264, C.I. I. Pigment violet 1 (rhodamine lake), 3, 5: 1, 16, 19, 23, 38, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue), 15: 1, 15: 2, 15: 3, 15: 4 (phthalocyanine blue), 16, 17: 1, 56, 60, 63, C.I. I. Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc.
The dye is not particularly limited, and an acid dye, a direct dye, a reactive dye, and a basic dye can be used. One kind may be used alone, or two or more kinds may be used in combination.
Examples of the dye include C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. I. Acid Red 52, 80, 82, 249, 254, 289, C.I. I. Acid Blue 9, 45, 249, C.I. I. Acid Black 1, 2, 24, 94, C.I. I. Food Black 1, 2, C.I. I. Direct Yellow 1,12,24,33,50,55,58,86,132,142,144,173, C.I. I. Direct Red 1,4,9,80,81,225,227, C.I. I. Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, C.I. I. Directed Black 19, 38, 51, 71, 154, 168, 171, 195, C.I. I. Reactive Red 14, 32, 55, 79, 249, C.I. I. Reactive black 3, 4, and 35 are mentioned.

  The content of the color material in the ink is preferably 0.1% by mass or more and 15% by mass or less, more preferably 1% by mass or more and 10% by mass from the viewpoints of improvement in image density, good fixability and ejection stability. It is as follows.

In order to disperse the pigment in the ink, a method of introducing a hydrophilic functional group into the pigment to form a self-dispersing pigment, a method of dispersing the pigment surface by coating with a resin, a method of dispersing using a dispersant, Etc.
Examples of a method for introducing a hydrophilic functional group into a pigment to form a self-dispersing pigment include a self-dispersing pigment that can be dispersed in water by adding a functional group such as a sulfone group or a carboxyl group to the pigment (for example, carbon). Can be used.
As a method for coating the surface of the pigment with a resin and dispersing it, a method in which the pigment is included in microcapsules and can be dispersed in water can be used. This can be paraphrased as a resin-coated pigment. In this case, it is not necessary that all pigments blended in the ink are coated with a resin, and within a range where the effects of the present invention are not impaired, uncoated pigments and partially coated pigments are dispersed in the ink. It may be.
Examples of the method of dispersing using a dispersant include a method of dispersing using a known low-molecular type dispersant or high-molecular type dispersant represented by a surfactant.
As the dispersant, for example, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, or the like can be used depending on the pigment.
RT-100 (nonionic surfactant) manufactured by Takemoto Yushi Co., Ltd. and naphthalenesulfonic acid Na formalin condensate can also be suitably used as a dispersant.
A dispersing agent may be used individually by 1 type, or may use 2 or more types together.

<Pigment dispersion>
An ink can be obtained by mixing a material such as water or an organic solvent with a color material. Further, it is also possible to produce an ink by mixing a pigment, other water, a dispersant, and the like into a pigment dispersion and mixing a material such as water or an organic solvent.
The pigment dispersion is obtained by dispersing water, a pigment, a pigment dispersant, and other components as required, and adjusting the particle size. For dispersion, a disperser is preferably used.
The particle size of the pigment in the pigment dispersion is not particularly limited, but the maximum frequency is 20 nm or more in terms of maximum number because the pigment dispersion stability is good and the image quality such as ejection stability and image density is also high. 500 nm or less is preferable and 20 nm or more and 150 nm or less are more preferable. The particle size of the pigment can be measured using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).
The content of the pigment in the pigment dispersion is not particularly limited and may be appropriately selected depending on the intended purpose. However, from the viewpoint of obtaining good ejection stability and increasing the image density, 0.1% by mass. % To 50% by mass is preferable, and 0.1% to 30% by mass is more preferable.
The pigment dispersion is preferably degassed by filtering coarse particles with a filter, a centrifugal separator or the like, if necessary.

<Resin>
The type of resin contained in the ink is not particularly limited and can be appropriately selected according to the purpose. For example, urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene Resin, styrene-butadiene resin, vinyl chloride resin, acrylic styrene resin, acrylic silicone resin, and the like. These may be used individually by 1 type and may use 2 or more types together.
Among these, acrylic silicone resins and urethane resins are particularly preferable. You may use the resin particle which consists of these.

The resin can be added to the ink in the state of a resin emulsion dispersed with water as a dispersion medium, and can be mixed with a material such as a coloring material or an organic solvent.
As said resin, what was synthesize | combined suitably may be used and a commercial item may be used.

The glass transition temperature (Tg) of the resin is preferably −45 ° C. or more and 0 ° C. or less because it greatly contributes to the fixability of the ink when a drying process is performed after recording.
The glass transition temperature is measured, for example, using a differential scanning calorimetry (DSC) device (device name: DSC120U, manufactured by Seiko Instruments Inc.), with a measurement temperature of 30 ° C. to 300 ° C. and a temperature increase of 2.5 ° C. per minute. It can be measured by speed.

The volume average particle diameter of the resin particles is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10 nm or more and 1,000 nm or less from the viewpoint of obtaining good fixability and high image hardness. It is more preferably 200 nm or less and particularly preferably 10 nm or more and 100 nm or less.
The volume average particle diameter can be measured using, for example, a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

  There is no restriction | limiting in particular as content of the said resin, Although it can select suitably according to the objective, 1 mass% or more and 10 mass% or less are preferable with respect to the ink whole quantity, and 1 mass% or more and 5 mass% or less. Is more preferable. When the content is 1% by mass or more, fixability can be improved, and when the content is 10% by mass or less, the storage stability of the ink can be improved.

<Wax>
The ink preferably contains a wax in order to impart slipperiness to the image area.
The wax is not particularly limited and may be appropriately selected depending on the intended purpose. However, polyethylene wax and carnauba wax are preferable from the viewpoints of film formability and slipperiness when ink is applied to the image area.
As the polyethylene wax, commercially available products can be used. Examples of the commercially available products include Nopcoat series manufactured by San Nopco, Nopcomal series manufactured by San Nopco, Hitech series manufactured by Toho Chemical Co., Ltd., and Big Chemie. -AQUACER series (for example, AQUACER-515) by Japan Corporation etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together.
As the carnauba wax, a commercially available product can be used, and examples of the commercially available product include Cellosol 524, Trasol CN and the like manufactured by Chukyo Yushi Co., Ltd. These may be used individually by 1 type and may use 2 or more types together.

  There is no restriction | limiting in particular as melting | fusing point of the said wax, Although it can select suitably according to the objective, 80 to 140 degreeC is preferable and 100 to 140 degreeC is more preferable. When the melting point is 80 ° C. or higher, the wax is less likely to be excessively melted or solidified even in a room temperature environment, and the storage stability of the ink can be maintained. Further, when the melting point is 140 ° C. or less, the wax is sufficiently melted even in a room temperature environment, and slipperiness can be imparted to the image portion.

The volume average particle diameter of the wax is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.01 μm or more, more preferably 0.01 μm or more and 0.1 μm or less. When the volume average particle size is 0.01 μm or more, the wax particles are easily oriented on the image surface, and slipperiness can be imparted to the image portion.
The volume average particle size can be measured using, for example, a particle size analyzer (device name: Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

  The content of the wax is preferably 1% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 5% by mass or less with respect to the total amount of the ink. When the content is 1% by mass or more and 10% by mass or less, the slipperiness of the image portion is improved.

The number average particle size of the solid content in the ink is not particularly limited and can be appropriately selected according to the purpose. The maximum frequency is preferably 20 nm to 1,000 nm, and more preferably 400 nm to 600 nm.
The solid content of the ink includes coloring material particles, resin particles, wax, and the like. The number average particle diameter can be measured using, for example, a particle size analyzer (device name: Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

<Additives>
If necessary, a surfactant, an antifoaming agent, an antiseptic / antifungal agent, a rust inhibitor, a pH adjuster, and the like may be added to the ink.

<Surfactant>
As the surfactant, any of silicone surfactants, fluorine surfactants, amphoteric surfactants, nonionic surfactants and anionic surfactants can be used.
There is no restriction | limiting in particular in silicone type surfactant, According to the objective, it can select suitably. Among them, those that do not decompose even at high pH are preferable, and examples thereof include side chain modified polydimethylsiloxane, both terminal modified polydimethylsiloxane, one terminal modified polydimethylsiloxane, and side chain both terminal modified polydimethylsiloxane. Those having an oxyethylene group or a polyoxyethylene polyoxypropylene group are particularly preferred because they exhibit good properties as an aqueous surfactant. In addition, as the silicone surfactant, a polyether-modified silicone surfactant can be used, and examples thereof include a compound in which a polyalkylene oxide structure is introduced into the side chain of the Si portion of dimethylsiloxane.
Examples of the fluorosurfactant include a perfluoroalkyl sulfonic acid compound, a perfluoroalkyl carboxylic acid compound, a perfluoroalkyl phosphate compound, a perfluoroalkyl ethylene oxide adduct, and a perfluoroalkyl ether group in the side chain. Polyoxyalkylene ether polymer compounds are particularly preferred because of their low foaming properties. Examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid, perfluoroalkyl sulfonate, and the like. Examples of the perfluoroalkylcarboxylic acid compound include perfluoroalkylcarboxylic acid and perfluoroalkylcarboxylate. Examples of the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain include a sulfate ester salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain and a perfluoroalkyl ether group in the side chain. Examples thereof include salts of polyoxyalkylene ether polymers. As counter ions of salts in these fluorosurfactants, Li, Na, K, NH ₄ , NH ₃ CH ₂ CH ₂ OH, NH ₂ (CH ₂ CH ₂ OH) ₂ , NH (CH ₂ CH ₂ OH) ₃ etc. are mentioned.
Examples of amphoteric surfactants include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine.
Nonionic surfactants include, for example, polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkylamine, polyoxyethylene alkylamide, polyoxyethylene propylene block polymer, sorbitan fatty acid ester, polyoxyethylene sorbitan Examples include fatty acid esters and ethylene oxide adducts of acetylene alcohol.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, laurate, polyoxyethylene alkyl ether sulfate salt, and the like.
These may be used alone or in combination of two or more.

The silicone surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, side chain modified polydimethylsiloxane, both terminal modified polydimethylsiloxane, one terminal modified polydimethylsiloxane, side Since both ends of the chain are modified with polydimethylsiloxane, a polyether-modified silicone surfactant having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying group exhibits good properties as an aqueous surfactant. preferable.
As such a surfactant, an appropriately synthesized product or a commercially available product may be used. Commercially available products can be obtained from, for example, Big Chemie Co., Ltd., Shin-Etsu Chemical Co., Ltd., Toray Dow Corning Silicone Co., Ltd., Nippon Emulsion Co., Ltd., and Kyoeisha Chemical Co., Ltd.
There is no restriction | limiting in particular as said polyether modified silicone surfactant, According to the objective, it can select suitably, For example, the polyalkylene oxide structure represented by a general formula (S-1) type | formula is dimethylpolyethylene. Examples thereof include those introduced into the side chain of Si part of siloxane.
[General Formula (S-1)]
(In the general formula (S-1), m, n, a, and b represent integers. R and R ′ represent an alkyl group and an alkylene group.)
A commercial item can be used as said polyether modified silicone type surfactant, For example, KF-618, KF-642, KF-643 (Shin-Etsu Chemical Co., Ltd.), EMALEX-SS-5602, SS- 1906EX (Japan Emulsion Co., Ltd.), FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, FZ-2164 (Toray Dow Corning Silicone Co., Ltd.), BYK-33, BYK-387 (Bic Chemie Co., Ltd.), TSF4440, TSF4452, TSF4453 (Toshiba Silicon Co., Ltd.), etc. are mentioned.

As the fluorine-based surfactant, a fluorine-substituted compound having 2 to 16 carbon atoms is preferable, and a fluorine-substituted compound having 4 to 16 carbon atoms is more preferable.
Examples of the fluorosurfactant include perfluoroalkyl phosphate compounds, perfluoroalkylethylene oxide adducts, and polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group in the side chain.
Among these, a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain is preferable because of its low foaming property, and in particular, fluorine-based compounds represented by the general formulas (F-1) and (F-2) A surfactant is preferred.
[General Formula (F-1)]
In the compound represented by the general formula (F-1), m is preferably an integer of 0 to 10 and n is preferably an integer of 0 to 40 in order to impart water solubility.
[General Formula (F-2)]
_{C n F 2n + 1- CH 2} CH (OH) CH 2 -O- (CH 2 CH 2 O) a -Y
In the compound represented by the general formula (F-2), Y is H, or CnF _{2n + 1} , n is an integer of 1 to 6, or CH ₂ CH (OH) CH ₂ —CnF _{2n + 1,} where n is 4 to 6. An integer, or CpH _{2p + 1} , p is an integer of 1-19. a is an integer of 4-14.
A commercial item may be used as said fluorosurfactant. As this commercial item, for example, Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, S-145 (all manufactured by Asahi Glass Co., Ltd.); Fullrad FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (all manufactured by Sumitomo 3M Limited); Megafac F-470, F -1405, F-474 (all manufactured by DIC Corporation); Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR (all manufactured by DuPont) ); FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW (all manufactured by Neos Co., Ltd.), Refox PF-136A, PF-156A, PF-151N, PF-154, PF-159 (manufactured by Omninova), Unidyne DSN-403N (manufactured by Daikin Kogyo Co., Ltd.), etc., among these, good printing PF-300 manufactured by DuPont, FT-110 manufactured by Neos, FT-250, FT-251, FT -400S, FT-150, FT-400SW, Polynova PF-151N manufactured by Omninova, and Unidyne DSN-403N manufactured by Daikin Industries, Ltd. are particularly preferable.

  There is no restriction | limiting in particular as content of surfactant in an ink, Although it can select suitably according to the objective, From the point which is excellent in wettability and discharge stability, and image quality improves, it is 0.001 mass. % To 5% by mass is preferable, and 0.05% to 5% by mass is more preferable.

<Antifoaming agent>
There is no restriction | limiting in particular as an antifoamer, For example, a silicone type antifoamer, a polyether type | system | group antifoamer, a fatty-acid ester type | system | group antifoamer etc. are mentioned. These may be used alone or in combination of two or more. Among these, a silicone type antifoaming agent is preferable from the viewpoint of excellent foam breaking effect.

<Antiseptic and antifungal agent>
The antiseptic / antifungal agent is not particularly limited, and examples thereof include 1,2-benzisothiazolin-3-one.

<Rust preventive>
There is no restriction | limiting in particular as a rust preventive agent, For example, acidic sulfite, sodium thiosulfate, etc. are mentioned.

<PH adjuster>
The pH adjuster is not particularly limited as long as the pH can be adjusted to 7 or more, and examples thereof include amines such as diethanolamine and triethanolamine.

-Ink physical properties-
The physical properties of the ink are not particularly limited, and viscosity, dynamic surface tension, pH, and the like can be appropriately selected according to the purpose.

[Hunter Whiteness]
In the present invention, an image formed with the ink having a Hunter whiteness of 20 or more is defined as white.
The Hunter whiteness is preferably 60 or more, and more preferably 60 or more and 90 or less. When the Hunter whiteness is 60 or more, white can be expressed without being affected by the background color of the recording medium. When the Hunter whiteness is 90 or less, fixability and productivity can be further maintained.
The Hunter whiteness can be determined as follows.
By using a recording apparatus (apparatus name: IPSiO GXe5500, manufactured by Ricoh Co., Ltd.), the ink was recorded on a recording medium (trade name: Lumina Color Black 128 gsm, manufactured by Oji Ftex Co., Ltd.) at a recording resolution of 1,200 dpi × 1,200 dpi. And an adhesion amount of ² mg / cm ² and dried at 90 ° C. for 60 seconds to obtain an image formed. L ^* , a ^* , and b ^* of the obtained image were measured using a spectroscopic color densitometer (device name: X-Rite 939, manufactured by X-Rite). Whiteness can be calculated.
Hunter whiteness = 100 − [(100−L ^* ) ² + (a ^{* 2} + b ^{* 2} )] ^0.5 Formula (6)

[Difference in sedimentation before and after standing]
In the ink of the present invention, the difference in sedimentation degree (MV value) between before and after being left standing for a long time is preferably −2 or more, and more preferably −2 to 0. When the difference in the sedimentation degree is −2 or more, the sedimentation of the colorant that affects the ink ejection characteristics can be prevented even when the ink is left standing for a long time. When the difference in the sedimentation degree is 0 or less, it is possible to prevent only the hollow resin particles from floating in the ink.
The difference in the MV value is determined, for example, by allowing the ink to stand in an environment of 25 ° C. for 168 hours, and determining the sedimentation degree of the ink before and after standing for 168 hours (device name: Turbi scan). It can be calculated by subtracting the sedimentation degree before standing from the sedimentation degree of the obtained ink after standing for 168 hours.

[viscosity]
The viscosity of the ink at 25 ° C. is preferably 5 mPa · s or more and 30 mPa · s or less, from the viewpoint of improving printing density and character quality and obtaining good ejection stability. S or less is more preferable.
The viscosity can be measured by, for example, a rotary viscometer (device name: RE-80L, manufactured by Toki Sangyo Co., Ltd.). Measurement conditions are 25 ° C., standard cone rotor (1 ° 34 ′ × R24), sample liquid amount 1.2 mL, rotation speed 50 rpm, and measurement is possible for 3 minutes.

[Dynamic surface tension]
The dynamic surface tension of the ink is 20 mN / m under the conditions that the bubble life time is 1,500 ms and 25 ° C., because the ink is suitably leveled on the recording medium and the drying time of the ink is shortened. It is preferably 35 mN / m or less.
The dynamic surface tension is a value measured at 25 ° C. by the maximum bubble pressure method, and can be measured using, for example, a dynamic surface tension meter (manufactured by SITA Messtechnik). The “bubble lifetime” is the lifetime of bubbles generated in the maximum bubble pressure method, also referred to as “surface lifetime”, and the maximum bubble pressure from the point when a new interface is generated in the probe tip of the dynamic surface tension meter. It means time to become.

[PH]
The pH of the ink is preferably 7 to 12 and more preferably 8 to 11 in a 25 ° C. environment from the viewpoint of preventing corrosion of the metal member in contact with the liquid.

(Pretreatment liquid)
The pretreatment liquid contains a flocculant, an organic solvent, and water, and may contain a surfactant, an antifoaming agent, a pH adjuster, an antiseptic / antifungal agent, an antirust agent, and the like as necessary.
For organic solvents, surfactants, antifoaming agents, pH adjusters, antiseptic / antifungal agents, and rust preventive agents, the same materials as those used for ink can be used, and other materials used for known processing liquids can be used. .
The type of the flocculant is not particularly limited, and examples thereof include water-soluble cationic polymers, acids, and polyvalent metal salts.

(Post-treatment liquid)
The post-treatment liquid is not particularly limited as long as a transparent layer can be formed. The post-treatment liquid is obtained by selecting and mixing an organic solvent, water, resin, surfactant, antifoaming agent, pH adjuster, antiseptic / antifungal agent, rust inhibitor, and the like as necessary. Further, the post-treatment liquid may be applied to the entire recording area formed on the recording medium, or may be applied only to the area where the ink image is formed.

(recoding media)
The recording medium is not particularly limited, and plain paper, glossy paper, special paper, cloth, and the like can be used. Good image formation is possible even with a non-permeable substrate.
The non-permeable base material is a base material having a surface with low water permeability and absorbability, and includes materials that do not open to the outside even if there are many cavities inside, more quantitatively. In the Bristow method, it refers to a substrate having a water absorption of 10 mL / m 2 or less from the start of contact until 30 msec 1/2.
As said non-permeable base material, plastic films, such as a vinyl chloride resin film, a polyethylene terephthalate (PET) film, a polypropylene, polyethylene, a polycarbonate film, can be used conveniently, for example.

(Recorded material)
The ink recorded matter of the present invention has an image formed using the ink of the present invention on a recording medium.
Recording can be performed by recording with an inkjet recording apparatus and an inkjet recording method.

(Recording method and recording apparatus)
The recording method of the present invention includes an ink application process and a drying process, and includes other processes as necessary.
The recording apparatus of the present invention includes an ink application unit and a drying unit, and includes other units as necessary.
The recording method can be preferably implemented by the recording apparatus.

<Ink application step and ink application means>
The ink application step is a step of performing recording by ejecting the ink onto the recording medium. It should be noted that a step of attaching various treatment liquids or the like to the recording medium may be included before or after application of the ink.
The ink applying unit is a unit that performs recording by discharging the ink, various processing liquids, and the like onto the recording medium.
The ink application process can be suitably performed by the ink application means.
The recording medium means a medium on which ink or various processing liquids can be temporarily attached.

  The recording method and the recording apparatus can be suitably used for various recording apparatuses using an inkjet recording method, such as a printer, a facsimile apparatus, a copying apparatus, a printer / fax / copier multifunction machine, and a three-dimensional modeling apparatus.

  The recording method and the recording apparatus are not limited to those in which significant images such as characters and figures are visualized by ink. For example, what forms patterns, such as a geometric pattern, etc. includes what forms a three-dimensional image.

  The recording apparatus may include not only a head portion for ejecting ink but also means for feeding, transporting, and discharging a recording medium, and other devices called pre-processing devices and post-processing devices. .

Unless specifically limited, the recording apparatus includes both a serial type apparatus that moves the ejection head and a line type apparatus that does not move the ejection head.
In addition, this recording apparatus can use not only a desktop type but also a wide recording apparatus that can print on an A0 size recording medium, or a continuous paper wound in a roll shape, for example. Also included are continuous paper printers.

<Drying process and drying means>
The drying step is a step of drying the recording medium.
The drying means is means for drying the recording medium.
The drying step can be preferably performed by the drying means.
The drying means includes, for example, means for drying and heating the recording surface and the back surface of the recording medium. Although it does not specifically limit as said drying means, For example, a warm air heater and an infrared heater can be used. The drying can be performed before, during or after recording.

There is no restriction | limiting in particular in the said drying process and the said drying means, According to the objective, heating temperature, a heating time, etc. can be selected suitably.
As said heating temperature, 50 to 170 degreeC is preferable, 70 to 150 degreeC is more preferable, 90 to 150 degreeC is further more preferable, 120 to 150 degreeC is especially preferable. When the heating temperature is 50 ° C. or higher, fixability can be improved. Hunter whiteness can be improved as the said heating temperature is 170 degrees C or less.
The heating time is preferably 5 seconds to 90 seconds, more preferably 10 seconds to 60 seconds, and particularly preferably 10 seconds to 30 seconds. When the heating time is 5 seconds or longer, fixability can be improved. Hunter whiteness can be improved as the said heating time is 90 second or less.

An example of the recording apparatus will be described with reference to FIGS. FIG. 1 is a perspective view of the apparatus. FIG. 2 is an explanatory perspective view of the main tank.
An image forming apparatus 400 as an example of a recording apparatus is a serial type image forming apparatus. A mechanism unit 420 is provided in the exterior 401 of the image forming apparatus 400. Each ink storage portion 411 of the main tank 410 (410k, 410c, 410m, 410y) for each color of black (K), cyan (C), magenta (M), yellow (Y) is, for example, an aluminum laminate film or the like. It is formed of a packaging member. The ink storage unit 411 is stored in, for example, a plastic storage container case 414. The main tank 410 is used as an ink cartridge for each color.
A cartridge holder 404 is provided on the inner side of the opening when the cover 401c of the apparatus main body is opened. A main tank 410 is detachably attached to the cartridge holder 404. Thus, the ink discharge ports 413 of the main tank 410 and the discharge heads 434 for the respective colors communicate with each other via the supply tubes 436 for the respective colors, and ink can be discharged from the discharge heads 434 to the recording medium.

The recording apparatus can include not only a portion that ejects ink but also a device called a pre-processing device or a post-processing device.
As one mode of the pretreatment device and the posttreatment device, as in the case of inks such as black (K), cyan (C), magenta (M), and yellow (Y), a pretreatment liquid and a posttreatment liquid are included. There is a mode in which a liquid container and a liquid discharge head are added, and a pretreatment liquid and a posttreatment liquid are discharged by an ink jet recording method.
As another aspect of the pretreatment apparatus and the posttreatment apparatus, there is an aspect in which, for example, a pretreatment apparatus or a posttreatment apparatus other than the ink jet recording method is provided by a blade coating method, a roll coating method, or a spray coating method.

  The method of using the ink is not limited to the ink jet recording method, and can be widely used. Besides the ink jet recording method, for example, a blade coating method, a gravure coating method, a bar coating method, a roll coating method, a dip coating method, a curtain coating method, a slide coating method, a die coating method, a spray coating method and the like can be mentioned.

The use of the ink of the present invention is not particularly limited and can be appropriately selected depending on the purpose. For example, it can be applied to printed materials, paints, coating materials, foundations and the like. Furthermore, it can be used not only to form two-dimensional characters and images using ink, but also as a three-dimensional modeling material for forming a three-dimensional three-dimensional image (three-dimensional modeled object).
A known three-dimensional modeling apparatus for modeling a three-dimensional model can be used, and is not particularly limited. For example, a three-dimensional modeling apparatus including an ink storage unit, a supply unit, a discharge unit, a drying unit, or the like is used. be able to. The three-dimensional structure includes a three-dimensional structure obtained by repeatedly applying ink. Further, a molded product obtained by processing a structure provided with ink on a substrate such as a recording medium is also included. The molded product is obtained by subjecting a recorded material or a structure formed in a sheet shape or a film shape to a molding process such as heat stretching or punching, for example, an automobile, an OA device, an electric -It is suitably used for applications in which surfaces are decorated after decorating, such as meters for electronic devices, cameras, etc., and panels for operation units.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

  In addition, “Hollow resin particles and ink X and Y”, “50% cumulative volume particle diameter of hollow resin particles”, and “mixing SP value of organic solvent” were measured as follows.

<Hollow resin particles and ink X and Y>
Hollow resin particles were prepared in the following, and more IR spectrum of the ink, the maximum value X of the peak at 1,600Cm ^-1, and 1,730cm the maximum value Y of the peak at ^-1, microscopic FT-IR measuring apparatus (apparatus Name: iN10MX / iZ10, manufactured by Thermo Fisher Scientific Co., Ltd.) and analysis software (trade name: OMNIC, manufactured by Thermo Fisher Scientific Co., Ltd.).
X and Y in the IR spectrum of the ink almost coincided with X and Y in the IR spectrum of the hollow resin particles.
Moreover, the peak ratio (Y / X) was calculated from the obtained X and Y.

<50% cumulative volume particle size of hollow resin particles>
The 50% cumulative volume particle size of the hollow resin particles produced below was measured using a particle size analyzer (device name: Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

<Mixed SP value of organic solvent>
The mixed SP value in a mixed solution of organic solvents contained in the ink prepared below was calculated from the following formula (2). However, when only one organic solvent was used, the SP value of the one organic solvent was used as the mixed SP value.
Mixed SP value (cal / cm ³ ) in mixed solution of organic solvent in produced ink ^0.5
= [SP value of organic solvent A x volume fraction of organic solvent A] + [SP value of organic solvent B x volume fraction of organic solvent B] + ... Formula (2)

(Preparation example 1 of hollow resin particles)
<Preparation of hollow resin particle B>
<< Synthesis of seed particle emulsion >>
A four-necked separable flask equipped with a stirrer, thermometer, cooler, and dropping funnel is charged with ion-exchanged water (726.0 g), methyl methacrylate (5.0 g), and methacrylic acid (0.1 g) and stirred. While warming. And when the internal temperature in a separable flask became 70 degreeC, the 10 mass% ammonium persulfate solution (1.0g) was added, and it heated at 80 degreeC for 20 minutes. On the other hand, methyl methacrylate (141.0 g), methacrylic acid (94.9 g), anionic emulsifier, sodium alkylbenzenesulfonate (5.0 g, trade name: Neogen SF-20, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and Ion-exchanged water (120.0 g) was emulsified with a homodisper to make a pre-emulsion, and then charged into a dropping funnel.
Next, while maintaining the internal temperature in the separable flask at 80 ° C., the pre-emulsion obtained above was uniformly added dropwise over 3 hours, and at the same time, 10% by mass ammonium persulfate solution (10.0 g) was added to 3%. It was dripped uniformly over time. After completion of dropping, the mixture was aged at 80 ° C. for 3 hours, cooled, and filtered through a 120 mesh filter cloth to obtain a seed particle emulsion.

<< Synthesis of hollow resin particles >>
A four-necked separable flask equipped with a stirrer, a thermometer, a cooler, and a dropping funnel was charged with ion-exchanged water (188.2 g), the seed particle emulsion (66.0 g) was added, and the mixture was stirred while stirring. Warmed to ° C. On the other hand, butyl acrylate (2.4 g), butyl methacrylate (1.1 g), methyl methacrylate (19.5 g), methacrylic acid (0.7 g), sodium alkylbenzenesulfonate (5.0 g, trade name: Neogen SF-20) Daiichi Kogyo Seiyaku Co., Ltd.) and ion-exchanged water (55.3 g) were emulsified with a homodisper to give pre-emulsion 1 and then charged into a dropping funnel. Then, while maintaining the internal temperature in the separable flask at 80 ° C., the pre-emulsion 1 obtained above was dropped uniformly over 30 minutes, and at the same time, a 10% by mass sodium persulfate solution (1.2 g) was added. It was dripped uniformly over 30 minutes.

Next, styrene (75.0 g), sodium alkylbenzenesulfonate (5.0 g, trade name: Neogen SF-20, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and ion-exchanged water (51.8 g) are emulsified with a homodisper. And pre-emulsion 2 was added to the dropping funnel. Then, while maintaining the internal temperature of the separable flask at 80 ° C., 1 hour after the completion of the dropwise addition of the pre-emulsion 1, the pre-emulsion 2 obtained above was uniformly dropped over 60 minutes. At the same time, a 10 mass% sodium persulfate solution (3.5 g) was uniformly added dropwise over 60 minutes. After the dropping of Pre-Emulsion 2 was completed, 28% by mass of ammonia water (7.5 g) was added dropwise and aged at 80 ° C. for 1 hour. After cooling, the mixture was filtered through a 120 mesh filter cloth to obtain hollow resin particles B.
The hollow resin particle B emulsion had a peak ratio (Y / X) = 3.0, a 50% cumulative volume particle size: 600 nm, and a solid content concentration: 20% by mass.

(Preparation Example 2 of Hollow Resin Particles)
<Preparation of hollow resin particle C>
Hollow resin particles C were obtained in the same manner as in Hollow resin particle production example 1 except that the hollow resin particle production example 1 was changed to 39.0 g of styrene.
The hollow resin particle C emulsion had a peak ratio (Y / X) = 4.5, a 50% cumulative volume particle size: 600 nm, and a solid content concentration: 20.5% by mass.

(Preparation Example 3 of Hollow Resin Particles)
<Preparation of hollow resin particle D>
Hollow resin particles D were obtained in the same manner as in Hollow resin particle production example 1 except that the hollow resin particle production example 1 was changed to 22.3 g of styrene.
The hollow resin particle D emulsion had a peak ratio (Y / X) of 6.0, a 50% cumulative volume particle size: 400 nm, and a solid content concentration: 26% by mass.

Example 1
3-ethyl-3-hydroxymethyloxetane (manufactured by Tokyo Chemical Industry Co., Ltd., SP value = 11.0 (cal / cm ³ ) ^0.5 , boiling point: 110 ° C.) 33.0% by mass, silicone surfactant ( Product name: KF-640, manufactured by Shin-Etsu Chemical Co., Ltd.) 1.0% by mass, as an antifoaming agent, product name: KF-353 (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5% by mass, antibacterial agent, product Name: Proxel LV (S) (manufactured by Nitto Denko Avicia Co., Ltd.) 0.1 mass%, 2-amino-2-ethyl-1,3-propanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.4 as a pH adjuster Mass% and ion-exchanged water 54.0 mass% were stirred and mixed uniformly for 1 hour. Next, as a wax, polyethylene wax emulsion (trade name: AQUACER-515, manufactured by Big Chemie Japan Co., Ltd., melting point: 135 ° C., solid content concentration: 35% by mass) is added by 1.0% by mass, and further for 1 hour. Stir to mix evenly. Thereafter, 10.0% by mass of the hollow resin particle D emulsion (peak ratio (Y / X) = 6.0, 50% cumulative volume particle size: 400 nm, solid content concentration: 26% by mass) was added, and further 1 hour. Stir to mix evenly. This mixture was subjected to pressure filtration through a polyvinylidene fluoride membrane filter having an average pore diameter of 5 μm to remove coarse particles and dust, whereby the ink of Example 1 was produced. In addition, content of each hollow resin particle in Table 1 is the quantity as an emulsion.

(Examples 2 to 10 and Comparative Examples 1 to 4)
In Example 1, inks of Examples 2 to 10 and Comparative Examples 1 to 4 were prepared in the same manner as Example 1, except that the composition was changed as shown in Table 1, Table 2, and Table 4 below. did. In addition, content of each resin emulsion in Table 1, Table 2, and Table 4 is the quantity as an emulsion.

(Example 11)
1,2-propanediol (manufactured by Tokyo Chemical Industry Co., Ltd., SP value = 14.3 (cal / cm ³ ) ^0.5 , boiling point: 178 ° C.) 24.9% by mass, 1,2-butanediol (Tokyo Kasei) Manufactured by Kogyo Co., Ltd., SP value = 13.1 (cal / cm ³ ) ^0.5 , boiling point: 194 ° C., 8.0% by mass, silicone surfactant (trade name: KF-640, Shin-Etsu Chemical Co., Ltd.) Product name: KF-353 (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5 mass%, as antibacterial agent, product name: Proxel LV (S) (Nitto Denko Avicia) 0.1 mass%, 2-amino-2-ethyl-1,3-propanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.4 mass%, and ion-exchanged water 54.0 mass% Was stirred for 1 hour and mixed uniformly. Next, as resin, acrylic silicone resin emulsion (trade name: RKP-02, manufactured by Toyochem Co., Ltd., glass transition temperature (Tg) = − 7 ° C., solid content concentration: 40 mass%) 0.1 mass%, and wax As a polyethylene wax emulsion (trade name: AQUACER-515, manufactured by Big Chemie Japan Co., Ltd., melting point: 135 ° C., solid content concentration: 35 mass%) 1.0 mass% was added, and the mixture was further stirred for 1 hour to be uniform. Mixed. Thereafter, 10.0% by mass of the hollow resin particle D emulsion (peak ratio (Y / X) = 6.0, 50% cumulative volume particle size: 400 nm, solid content concentration: 26% by mass) was added, and further 1 hour. Stir to mix evenly. This mixture was subjected to pressure filtration through a polyvinylidene fluoride membrane filter having an average pore diameter of 5 μm to remove coarse particles and dust, and ink of Example 11 was produced.

(Examples 12 to 16)
Inks of Examples 12 to 16 were produced in the same manner as in Example 11 except that the composition was changed as shown in Table 2 and Table 3 in Example 11.

  Next, “difference in sedimentation”, “hunter whiteness”, and “fixing rate” were evaluated as follows. The results are shown in Tables 1 to 4 below.

<Difference in sedimentation before and after standing>
About 5 g of each of the obtained inks was placed in a 25 g capacity glass tube (trade name: Screw mouth test tube, manufactured by AS ONE Corporation) and allowed to stand in a 25 ° C. environment for 168 hours. The sedimentation degree of the ink before standing and after standing for 168 hours was measured with a sedimentation degree measuring device (device name: Turbiscan Classic MA2000, manufactured by Eihiro Seiki Co., Ltd.). The difference in the sedimentation degree was calculated by subtracting the sedimentation degree before standing from the sedimentation degree of the ink after standing for 168 hours. In addition, the difference in the sedimentation level is −2 or more, which is a feasible level.

[Image formation]
Each ink prepared was recorded on a recording medium (trade name: Lumina Color Black 127 gsm, manufactured by Oji F-Tex Co., Ltd.) with a recording device (device name: IPSiO GXe5500, manufactured by Ricoh Co., Ltd.) at 1,200 dpi × 1,200 dpi. The sample was deposited with a recording resolution and a deposition amount of ² mg / cm ² and dried by heating at 90 ° C. for 60 seconds to produce an image sample.
The recording chart used was a 3 cm square solid image formed with a dot pattern.

<Hunter whiteness>
About the solid image of each image sample, L ^* , a ^* , and b ^* are measured using a spectral side color densitometer (device name: X-Rite 939, manufactured by X-Rite), and the following equation (6) Hunter whiteness was calculated. In addition, a Hunter whiteness of 60 or more is a practicable level.
Hunter whiteness = 100 − [(100−L ^* ) ² + (a ^{* 2} + b ^{* 2} )] ^0.5 Formula (6)

<Fixing rate>
About the solid image of each image sample, cotton cloth (trade name: TexTile Innovators, manufactured by SDL ATLAS Co., Ltd.) was attached and rubbed 5 times with a clock meter (manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.) having a load of 9N. The image forming part before and after rubbing was measured with a spectral color densitometer (trade name: X-Rite 939, manufactured by X-Rite). The value before rubbing was taken as 100%, and the value after rubbing was shown as a percentage. The larger the value, the better the image fixability. Note that a fixing rate of 75% or more is a feasible level.

  Details of the ink components in Tables 1 to 4 are as follows.

<Hollow resin particles>
Hollow resin particle A emulsion (trade name: ROPAQUE ULTRA E, manufactured by Dow Chemical Co., Ltd., peak ratio (Y / X) = 1.5, 50% cumulative volume particle size: 400 nm, solid content concentration: 30% by mass)
Hollow resin particle E emulsion (trade name: SX868, manufactured by JSR Corporation, peak ratio (Y / X) = 9.3, 50% cumulative volume particle size: 600 nm, solid content concentration: 20.3% by mass)
Hollow resin particle F emulsion (trade name: X-212-902E, manufactured by Seiden Chemical Co., Ltd., peak ratio (Y / X) = 3.1, 50% cumulative volume particle size: 890 nm, solid content concentration: 28% by mass )

<Organic solvent>
・ Glycerin (manufactured by Sakamoto Pharmaceutical Co., Ltd., SP value = 17.4 (cal / cm ³ ) ^0.5 , boiling point: 290 ° C.)
1,2-propanediol (manufactured by Tokyo Chemical Industry Co., Ltd., SP value = 14.3 (cal / cm ³ ) ^0.5 , boiling point: 178 ° C.)
1,2-butanediol (manufactured by Tokyo Chemical Industry Co., Ltd., SP value = 13.1 (cal / cm ³ ) ^0.5 , boiling point: 194 ° C.)
・ 3-Ethyl-3-hydroxymethyloxetane (manufactured by Tokyo Chemical Industry Co., Ltd., SP value = 11.0 (cal / cm ³ ) ^0.5 , boiling point: 110 ° C.)
3-methoxy-N, N-dimethylpropionamide (manufactured by Idemitsu Kosan Co., Ltd., SP value = 9.2 (cal / cm ³ ) ^0.5 , boiling point: 216 ° C.)

<Resin>
Acrylic silicone resin emulsion (trade name: RKP-02, manufactured by Toyochem Co., Ltd., glass transition temperature (Tg) = − 7 ° C., solid content concentration: 40% by mass)
Urethane resin emulsion A (trade name: Superflex 420, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., glass transition temperature (Tg) = − 10 ° C., solid content concentration: 38% by mass)
Urethane resin emulsion B (trade name: Superflex 210, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., glass transition temperature (Tg) = 41 ° C., solid content concentration: 35 mass%)

<Wax>
Polyethylene wax emulsion (trade name: AQUACER-515, manufactured by Big Chemie Japan, melting point: 135 ° C., solid content concentration: 35 mass%)

<Surfactant>
・ Silicone surfactant (trade name: KF-640, manufactured by Shin-Etsu Chemical Co., Ltd.)

<Antifoaming agent>
・ Product name: KF-353, manufactured by Shin-Etsu Chemical Co., Ltd.

<Antimicrobial agent>
・ Product name: Proxel LV (S) (Nitto Denko Avicia)

<PH adjuster>
・ 2-Amino-2-ethyl-1,3-propanediol (manufactured by Tokyo Chemical Industry Co., Ltd.)

[Evaluation of effects on heat drying]
<Test Examples 1 to 7>
In the formation of the image, the image of the image of Example 5 was used in the same manner as in the formation of the image except that the heating conditions (heating temperature and heating time) after recording were changed as shown in Table 5 below. A sample was made. Using the produced image samples, the “hunter whiteness” and the “fixing rate” were evaluated in the same manner as in Example 1. The results are shown in Table 5 below.

As an aspect of this invention, it is as follows, for example.
<1> A hollow resin particle containing a structural unit represented by the following structural formula (1) and a copolymer having a structural unit represented by the following structural formula (2), an organic solvent, and water. in the IR spectrum of the hollow resin particles, and the maximum value of the peak at 1,600cm ^-1 ± 10cm ^-1 and X, the peak ratio when the maximum value of the peak at 1,730cm ^-1 ± 10cm ^-1 and the Y (Y / X) is 3.0 or more and 6.0 or less, and the mixed SP value of the organic solvent is 11.0 (cal / cm ³ ) ^0.5 or more and 15.5 (cal / cm ³ ) ^{0 .5} or less.
<2> The ink according to <1>, wherein the hollow resin particles have a 50% cumulative volume particle size of 400 nm to 600 nm.
<3> The ink according to any one of <1> to <2>, wherein the content of the hollow resin particles is 5.0% by mass or more and 12.5% by mass or less.
<4> The ink according to any one of <1> to <3>, further including at least one of acrylic silicone resin particles and urethane resin particles.
<5> The ink according to <4>, wherein a glass transition temperature of at least one of the acrylic silicone resin particles and the urethane resin particles is 0 ° C. or lower.
<6> The ink according to any one of <4> to <5>, wherein the content of at least one of the acrylic silicone resin particles and the urethane resin particles is 1% by mass or more and 10% by mass or less. .
<7> The ink according to any one of <1> to <6>, wherein the peak ratio (Y / X) is 3.0 or more and 5.5 or less.
<8> Ratio of the structural unit represented by the structural formula (1) and the structural unit represented by the structural formula (2) in the hollow resin particles (the structural unit represented by the structural formula (2) / the above The ink according to any one of <1> to <7>, wherein the structural unit represented by the structural formula (1) is 3.0 or more and 6.0 or less.
<9> The organic solvent is at least one selected from glycerin, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, isoprene glycol, and an oxetane compound. The ink according to any one of <1> to <8>, which is a seed.
<10> The ink according to any one of <1> to <9>, wherein the organic solvent has a boiling point of 250 ° C. or lower.
<11> The ink according to any one of <1> to <10>, further including a wax.
<12> The ink according to <11>, wherein the wax has a melting point of 80 ° C. or higher and 140 ° C. or lower.
<13> The ink according to any one of <11> to <12>, wherein a content of the wax is 1% by mass or more and 10% by mass or less.
<14> The ink according to any one of <1> to <13>, wherein the number average particle size of solids in the ink is 20 nm to 1,000 nm in terms of maximum number.
<15> The ink according to any one of <1> to <14>, wherein the ink has a viscosity at 25 ° C. of 5 mPa · s to 30 mPa · s.
<16> The dynamic surface tension of the ink according to any one of <1> to <15>, wherein the ink has a bubble lifetime of 1,500 ms and a temperature of 25 m to 20 mN / m to 35 mN / m. Ink.
<17> The above-mentioned <1> to <16, wherein a Hunter whiteness of an image formed by adhering the ink to a recording medium at an adhesion amount of ² mg / cm ² and drying at 90 ° C. for 60 seconds is 60 or more. > The ink according to any one of the above.
<18> The ink according to any one of <1> to <17>, wherein a difference in sedimentation degree before and after the ink is allowed to stand for 168 hours at 25 ° C. is −2 or more.
<19> An ink application step for applying the ink according to any one of <1> to <18> to a recording medium, and a drying step for drying the recording medium to which the ink has been applied. The recording method is characterized in that the heating temperature is 70 ° C. or more and 150 ° C. or less, and the heating time is 10 seconds or more and 60 seconds or less.
<20> An ink applying step of applying the ink according to any one of <1> to <18> to the recording medium, and a drying step of drying the recording medium applied with the ink, the drying step The recording method is characterized in that the heating temperature is from 120 ° C. to 150 ° C. and the heating time is from 10 seconds to 30 seconds.
<21> An ink applying unit that applies the ink according to any one of <1> to <18> to a recording medium; and a drying unit that dries the recording medium to which the ink is applied. In the recording apparatus, the heating temperature is from 70 ° C. to 150 ° C. and the heating time is from 10 seconds to 60 seconds.
<22> An ink applying unit that applies the ink according to any one of <1> to <18> to the recording medium; and a drying unit that dries the recording medium to which the ink has been applied. The recording apparatus is characterized in that the heating temperature in the means is 120 ° C. or higher and 150 ° C. or lower, and the heating time is 10 seconds or longer and 30 seconds or shorter.

  The ink according to any one of <1> to <18>, the recording method according to any one of <19> to <20>, and the recording apparatus according to any one of <21> to <22>. According to the above, the above-described problems can be solved and the object of the present invention can be achieved.

JP 2014-28964 A Japanese Patent No. 3747033

400 Image forming apparatus 401 Exterior of image forming apparatus 401c Cover of apparatus main body 404 Cartridge holder 410 Main tank 410k, 410c, 410m, 410y For each color of black (K), cyan (C), magenta (M), yellow (Y) Main tank 411 Ink storage section 413 Ink discharge port 414 Storage container case 420 Mechanism section 434 Discharge head 436 Supply tube

Claims (12)

A hollow resin particle containing a structural unit represented by the following structural formula (1) and a copolymer having a structural unit represented by the following structural formula (2), an organic solvent, and water,
Wherein in the IR spectrum of the hollow resin particles, 1,600cm ^-1 the maximum value of the peak at ± 10 cm ^-1 and X, the peak ratio when the maximum value of the peak at 1,730cm ^-1 ± 10cm ^-1 was Y ( Y / X) is 3.0 or more and 6.0 or less,
The ink having a mixed SP value of the organic solvent of 11.0 (cal / cm ³ ) ^0.5 or more and 15.5 (cal / cm ³ ) ^0.5 or less.
  The ink according to claim 1, wherein the hollow resin particles have a 50% cumulative volume particle size of 400 nm or more and 600 nm or less.   The ink according to claim 1, wherein the content of the hollow resin particles is 5.0% by mass or more and 12.5% by mass or less.   The ink according to any one of claims 1 to 3, further comprising at least one of acrylic silicone resin particles and urethane resin particles.   The ink according to claim 4, wherein a glass transition temperature of at least one of the acrylic silicone resin particles and the urethane resin particles is 0 ° C. or less.   The ink according to any one of claims 4 to 5, wherein the content of at least one of the acrylic silicone resin particles and the urethane resin particles is 1% by mass or more and 10% by mass or less. 7. The Hunter whiteness of an image formed by adhering the ink to a recording medium with an adhesion amount of ² mg / cm ² and drying at 90 ° C. for 60 seconds is 60 or more. Ink.   The ink according to any one of claims 1 to 7, wherein a difference in sedimentation degree before and after the ink is allowed to stand at 25 ° C for 168 hours is -2 or more. An ink application step of applying the ink according to any one of claims 1 to 8 to a recording medium;
Drying the recording medium to which the ink has been applied,
A recording method, wherein a heating temperature in the drying step is 70 ° C. or more and 150 ° C. or less, and a heating time is 10 seconds or more and 60 seconds or less. An ink application step of applying the ink according to any one of claims 1 to 8 to the recording medium;
Drying the recording medium to which the ink has been applied,
A recording method, wherein a heating temperature in the drying step is 120 ° C. or more and 150 ° C. or less, and a heating time is 10 seconds or more and 30 seconds or less. Ink application means for applying the ink according to any one of claims 1 to 8 to a recording medium;
Drying means for drying the recording medium provided with the ink,
A recording apparatus, wherein a heating temperature in the drying means is 70 ° C. or more and 150 ° C. or less, and a heating time is 10 seconds or more and 60 seconds or less. Ink application means for applying the ink according to any one of claims 1 to 8 to the recording medium;
Drying means for drying the recording medium provided with the ink,
A recording apparatus, wherein a heating temperature in the drying means is 120 ° C. or more and 150 ° C. or less, and a heating time is 10 seconds or more and 30 seconds or less.