JP2001199150A - Ink set, method for forming colored portion on recording medium, and ink jet recording apparatus - Google Patents

Abstract

(57) [Problem] Coloring with a wide color reproduction area, excellent color uniformity, effective suppression of bleeding at a color boundary portion where different color areas are adjacent on a recording material, and excellent scratch resistance. Provided is a method of forming a portion on a recording material, an ink jet recording apparatus, and an ink set excellent in ink jet recording characteristics such as storage stability and ejection stability of a recording head. SOLUTION: An ink set having independently an anionic or cationic aqueous ink containing a coloring material and a liquid composition containing fine particles whose surface is charged in the opposite polarity to the ink in a dispersed state. In addition, the ink and the liquid composition are adjusted such that the pH of the mixed liquid when each of them is mixed at a weight ratio of about 1 to 1 is at least a pH that causes aggregation of the coloring material. A set, a method for forming a colored portion on a recording medium, and an ink jet recording apparatus.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for obtaining an image having excellent color developability and color uniformity in forming a color image, and more particularly to a liquid composition which can be optimally used for image formation utilizing an ink jet recording system. The present invention relates to an ink set in which an object and a colored aqueous ink are combined, a method for forming a colored portion on a recording medium, and an ink jet recording apparatus.

[0002]

2. Description of the Related Art In an ink jet recording method, recording is performed by flying ink and attaching the ink to a recording medium such as paper. For example, Japanese Patent Publication No. 61-59911, Japanese Patent Publication No. 61-59912 and Japanese Patent Publication No. 61-5
According to an ink jet recording method disclosed in Japanese Patent No. 9914, in which an electric converter is used as a discharge energy supply unit and droplets are discharged by applying heat energy to ink to generate bubbles, High-density multi-orifices can be easily realized, and high-resolution and high-quality images can be recorded at high speed.

[0003] The ink used in the conventional ink jet recording method is mainly composed of water, and a water-soluble high-boiling solvent such as glycol for the purpose of preventing drying of the ink in the nozzles and clogging of the nozzles. Is generally contained. Therefore, when recording is performed on a recording medium using such an ink, sufficient fixability cannot be obtained, or due to uneven distribution of fillers and sizing agents on the recording paper surface as the recording medium. In some cases, problems such as generation of an estimated non-uniform image may occur. on the other hand,
In recent years, there has been a strong demand for ink-jet recorded materials to have the same high image quality as silver halide photographs, increasing the image density of ink-jet recorded images, expanding the color reproduction area, and recording. The technical demands for improving the color uniformity of objects are very high.

[0004] Under such circumstances, various proposals have been made so far in order to stabilize the ink jet recording method and to improve the quality of recorded matter by the ink jet recording method. As one of the proposals regarding the recording medium, a method of applying a filler or a sizing agent on the surface of the base paper of the recording medium has been proposed. For example, a base material is coated with porous fine particles that adsorb a coloring material as a filler,
A technique of forming an ink receiving layer by using the porous fine particles is disclosed. As a recording medium using these techniques, coated paper for ink jet printing and the like are sold.

[0005] Some typical other techniques for improving the quality of recorded matter are summarized below. (1) a method of internally adding a volatile solvent or a penetrating solvent to the ink;
Japanese Patent Application Laid-Open No. Sho 55-55
Japanese Patent No. 65269 discloses a method of adding a compound that enhances permeability such as a surfactant to an ink. or,
JP-A-55-66976 discloses the use of an ink mainly composed of a volatile solvent.

(2) A method of mixing an ink and a liquid composition that reacts with the ink on a recording medium; recording a recorded image for the purpose of improving image density, improving water resistance, and suppressing bleeding. Prior to or after the ejection of the ink, a method of applying a liquid composition for improving an image on a recording medium has been proposed.

For example, Japanese Patent Application Laid-Open No. 63-60783 discloses a method in which a liquid composition containing a basic polymer is applied and then recording is performed using an ink containing an anionic dye. JP-A-63-22681 discloses a recording method in which a first liquid composition containing a reactive species and a liquid composition containing a compound which reacts with the reactive species are mixed on a recording medium. Further, JP-A-63-2999971 discloses that after applying a liquid composition containing an organic compound having two or more cationic groups per molecule onto a recording medium, the composition further contains an anionic dye. A method for recording with ink is disclosed. JP-A-64-9279 discloses a method in which an acidic liquid composition containing succinic acid or the like is applied onto a recording medium, and recording is performed with an ink containing an anionic dye.

Further, JP-A-64-63185 discloses a method in which a liquid composition for insolubilizing a dye is applied prior to recording of ink. Furthermore,
JP-A-8-224595 discloses a method of using a liquid composition containing a cationic substance having a different molecular weight distribution region together with an ink containing an anionic compound, and JP-A-8-72393 discloses a method of using a liquid composition containing an anionic compound. It discloses a method of using a liquid composition containing a reactive substance and finely ground cellulose together with an ink, all of which have high image density, good print quality, good water resistance, good color reproducibility, and good images in bleeding. Is described. or,
JP-A-55-150396 discloses a method of imparting a water-resistant agent for forming a lake with a dye after recording on a recording medium with a dye ink, and it is proposed to impart water resistance to a recorded image. Have been.

(3) a method of mixing the ink and the fine particle-containing liquid composition on a recording medium;
Japanese Patent Application Publication No. 90-902010 discloses a method in which a colorless liquid containing colorless fine particles made of an inorganic substance is applied onto a recording medium, and then a non-aqueous recording liquid is attached thereto. After applying a solution containing, or a solution containing fine particles and a binder polymer on the recording medium,
A method for adhering an ink containing a pigment, a water-soluble resin, a water-soluble solvent and water is disclosed, and it is described that an image having good print quality and color development can be obtained regardless of the type of paper. .

(Background Art) The present inventors have repeatedly studied various ink jet recording techniques as described above, and as a result, although excellent effects can be confirmed with respect to each technical problem, in exchange for that, other effects are obtained. It has been found that the ink jet recording characteristics may be deteriorated. For example, by adopting the technique (1), although the fixability of the ink to the recording medium is improved, the image density is reduced, and the color which is important for recording on plain paper and recording a color image is improved. In some cases, the reproduction range was reduced. Further, according to the technique (2), the coloring material in the ink can be retained on the surface of the recording medium, so that a recorded matter having a high image density can be obtained. However, in some cases, the color reproduction range and saturation may be reduced, probably because the color material is aggregated on the surface of the recording medium.

The recording medium (hereinafter referred to as coated paper) obtained by applying a filler or a sizing agent on the surface of the base paper of the recording medium has been recognized as a technique capable of forming a high quality image. I have. In general, it is known that in order to obtain a high-saturation image, it is necessary to leave the colorant in a monomolecular state on the surface of the recording medium without agglomeration. Has such a function. However, in order to obtain high image density and image saturation,
For the coloring material in a given ink, it is indispensable to form a thick ink receiving layer that covers the base paper with a large amount of porous fine particles, and as a result, the texture of the base paper is lost. There is. The present inventors have speculated that the reason why the ink receiving layer is required to lose the texture of the base paper is that the coloring material is not efficiently adsorbed on the porous fine particles.

The following description is based on the assumption that a coated paper has one ink receiving layer. FIG. 9 schematically shows a cross section near the surface of the coated paper. In the figure, 90
1 is a base paper, and 903 is an ink receiving layer. Generally, the ink receiving layer 903 has porous fine particles 905 and an adhesive 907 for fixing them. When the ink is applied, the ink penetrates the gaps between the porous fine particles 905 by capillary action, and forms an ink penetrating portion 909. As shown in the figure, since the porous fine particles in the ink receiving layer have locally different densities, the manner of permeation of the ink by the capillary phenomenon differs depending on the location. Therefore, during the ink permeation process, the coloring material cannot uniformly contact the surface of the porous fine particles, and the coloring material is not efficiently adsorbed on the porous fine particles.

Further, there are portions where the penetration of ink is inhibited by the adhesive 907, and there are portions in the ink receiving layer 903 where the ink cannot penetrate, and portions that do not contribute to color development are generated. That is, in the conventional coated paper, the coloring material cannot be efficiently adsorbed in a monomolecular state with respect to the amount of the porous fine particles for the above-described reason,
As a result, in order to obtain a high quality image, a large amount of porous fine particles is required, which impairs the texture of the base paper.

On the basis of the above-described new findings, the present inventors have proposed a method for using fine particles having a function of adsorbing a coloring material and for efficiently adsorbing or binding a coloring material to the fine particles. It is effective to disperse the fine particles in a liquid phase and use the ink in a liquid state together with the ink. With such a configuration, it is possible to cause the color material and the fine particles to react in a liquid-liquid state. It has been found that the density and the saturation can be improved.

On the other hand, another technical problem in ink jet recording is a problem of bleeding. That is, when an attempt is made to form a multi-color image by an ink jet recording method, a plurality of inks of different colors need to be superimposed on the recording medium or applied so as to be adjacent to each other. Colors are blurred or mixed unevenly at the boundary of the different color area, thereby deteriorating the image quality. In order to obtain a high-quality multicolor image, suppression of bleed is also one important technical element.

Therefore, the present inventors have also solved the problem of bleed based on the above-mentioned technology for efficiently adsorbing or binding a coloring material to fine particles to improve image density and saturation. We have been studying technologies that can do this. The present invention has been brought about by such studies.

[0017]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an ink used for obtaining a higher quality ink jet recorded matter having a high density, a high chroma and a highly suppressed bleed. To provide a set.
Another object of the present invention is to provide a wide color reproduction region, excellent color uniformity, and to effectively suppress bleeding at a color boundary portion when different color regions are adjacent on a recording material. It is another object of the present invention to provide a method for forming a colored portion having excellent abrasion properties on a recording material.

Another object of the present invention is to provide a wide color reproduction range, excellent color uniformity, and effectively suppress bleeding at a color boundary when different color regions are adjacent on a recording material. Another object of the present invention is to provide a method capable of forming a colored portion having excellent scratch resistance on a recording material. Still another object of the present invention is to provide a colorant having a wide color reproduction range, excellent color uniformity, suppressing bleeding at an adjacent boundary between images of different colors, and further having good scratch resistance. It is an object of the present invention to provide an ink jet recording apparatus capable of forming a portion on a recording material. Still another object of the present invention is to provide an ink set which is excellent in storage stability and ejection stability from a recording head and has excellent ink jet recording characteristics.

[0019]

According to one embodiment of the present invention, an anionic or cationic aqueous ink containing a coloring material and fine particles whose surface is charged to a polarity opposite to that of the ink are dispersed. An ink set having independently a liquid composition contained in a state, wherein the ink and the liquid composition have a pH of a mixed liquid when mixed at a weight ratio of about 1: 1 at least in the color composition. An ink set is provided that is adjusted to a pH that causes coagulation of the material.

According to another embodiment of the present invention, the ink contains an anionic or cationic aqueous ink containing a coloring material and fine particles whose surface is charged to a polarity opposite to that of the ink in a dispersed state. An ink set having a liquid composition independently, the ink and the liquid composition,
Each p is adjusted so that the pH of the mixed solution obtained by mixing the respective components at a weight ratio of about 1 to 1 is such that the coloring material causes aggregation.
An ink set is provided in which H is adjusted.

According to another embodiment of the present invention, an ink containing an anionic or cationic coloring material and a liquid composition containing fine particles reactive with the coloring material in a dispersed state are independently provided. An ink set, wherein the fine particles in the liquid composition include a color material in the ink on the surface of the fine particles when the ink and the liquid composition are mixed in a liquid state with each other. The ink is allowed to be adsorbed or bound while maintaining the molecular state, and the pH of the mixed liquid when the ink and the liquid composition are mixed and subjected to a liquid-liquid reaction, the pH of the coloring material is increased. Provided is an ink set adjusted to have a pH that causes aggregation.

According to another embodiment of the present invention, there is provided independently an anionic or cationic ink containing a coloring material and a liquid composition containing fine particles reactive with the coloring material in a dispersed state. An ink set, wherein the fine particles in the liquid composition, when the ink and the liquid composition are mixed with each other in a liquid state, a color material in the ink on the surface of the fine particles, and the color material is an ink. Is adsorbed or bonded while maintaining the molecular state of the particles, thereby destabilizing the dispersion state of the fine particles and causing aggregation of the fine particles, and mixing the ink and the liquid composition. And the pH of the mixture when the liquid-liquid reaction is performed,
There is provided an ink set adjusted to have a pH that causes the color material to aggregate.

According to another embodiment of the present invention, a droplet of an anionic or cationic aqueous ink containing a coloring material and fine particles whose surface is charged in the opposite polarity to the ink are dispersed in a dispersed state. A step of discharging both liquid droplets toward the recording medium so that a state in which the liquid composition containing the liquid composition and the liquid composition are in contact with each other on the recording medium in a liquid-liquid state is achieved. A method of forming a colored portion on a recording medium, wherein the aqueous ink and the liquid composition each have a pH of a mixed liquid obtained by mixing the respective aqueous inks and the liquid composition at a weight ratio of about 1 to 1 at least by agglomeration of the coloring material. To form a colored portion on a recording medium that is adjusted to have a pH that causes

According to another embodiment of the present invention, an ink containing section containing an anionic or cationic aqueous ink containing a coloring material, and fine particles whose surface is charged to the opposite polarity to the ink. An ink jet recording apparatus is provided, comprising: a liquid composition storage section that stores a liquid composition containing the liquid composition in a dispersed state; and a head for discharging each of the aqueous ink and the liquid composition. You.

According to still another embodiment of the present invention, an ink containing an anionic or cationic coloring material and a liquid composition containing fine particles reactive with the coloring material in a dispersed state are used. An image having a colored portion formed by reacting, the colored portion includes the fine particles and the aggregate of the coloring material, in which the coloring material is uniformly adsorbed or bonded to the surface with a single molecule. An image is provided.

[0026]

Next, the present invention will be described in more detail with reference to preferred embodiments. An ink set according to one embodiment of the present invention is a liquid composition comprising, in a dispersed state, an anionic or cationic aqueous ink containing a coloring material, and fine particles having a surface charged to a polarity opposite to that of the aqueous ink. Wherein the pH of the mixed liquid when the aqueous ink and the liquid composition are mixed at a weight ratio of about 1 to 1 is at least agglomeration of the coloring material. It has one feature in that the pH is adjusted to cause the pH.

According to the present invention having the above-described structure, it has a wide color reproduction region, is excellent in color uniformity, can effectively suppress bleeding at a color boundary portion, and further has good scratch resistance. This has the effect that an ink-jet recorded matter having the above-mentioned characteristics can be formed stably. In addition, as described above, the aqueous ink and the liquid composition used for recording have a very simple configuration, so that both the aqueous ink and the liquid composition have excellent storage stability, and as a result, high quality Also, there is an effect that an image can be formed stably with a high ink jet recording quality.

Although it is not clear why the above-mentioned excellent effects are exhibited by the present invention, the present inventors believe that the reason is as follows. Hereinafter, a recorded image according to the present invention will be described with reference to FIG. First,
Before the explanation, words are defined. In the present invention,
The “monomolecular state” indicates that a coloring material such as a dye or a pigment substantially maintains a dissolved or dispersed state in the ink. At this time, even if the coloring material causes some aggregation, the coloring material is included in the “monomolecular state” as long as the saturation is not reduced. For example, in the case of a dye,
Since it is considered preferable to be a single molecule, a color material other than the dye is also referred to as “monomolecular state” for convenience.

FIG. 14 is a diagram schematically showing a state in which a coloring portion I of a recorded image according to the present invention is composed of a main image portion IM and a peripheral portion IS thereof. In FIG. 14, reference numeral 1401 denotes a recording medium, and 1402 denotes a gap generated between fibers of the recording medium. 1403 is the color material 140
5 schematically shows fine particles which are chemically adsorbed. As shown in FIG. 14, in the ink-jet recorded image of the present invention, the main image portion IM has a uniform surface of the color material 1405 in a state of a single molecule or a state close to a single molecule (hereinafter, abbreviated as “monomolecular state”). And a fine particle aggregate 1407 that retains the colorant in a monomolecular state. Reference numeral 1409 denotes an aggregate of fine particles existing near the recording medium fibers in the main image area IM. The main image portion IM is formed by a process in which the fine particles 1403 are physically or chemically adsorbed on the recording medium fibers, a color material 1405 and the fine particles 143.
03 is formed by a process of adsorbing in a liquid-liquid state. Therefore, even in a recording medium such as plain paper in which the ink easily sinks, the image density and saturation are high, and an image having a wide color reproduction range comparable to that of coated paper can be formed even on a recording medium such as plain paper in which the coloring properties of the coloring material itself are not impaired. It becomes possible.

According to the knowledge of the present inventors, when an aqueous ink and a liquid composition are recorded on a recording paper as a recording medium at a weight ratio of about 1 to 1 (that is, on a recording medium). When each dot is printed one dot at a time), the color material adsorbed by the fine particles is only about 30 to 50% of the entire color material. That is, the remaining 50 to 70% of the coloring material is not affected by the fine particles in the liquid composition, and contributes to the formation of the colored portion by dispersion, penetration or dispersion and penetration. The present inventors can achieve a color reproduction range similar to that of coated paper, even if the color material adsorbed on the surface of the fine particles is less than half of the entire color material contained in the ink, It has been confirmed that the presence of a coloring material that does not contribute to the reaction with the fine particles forms a very small bleeding around the pixel, and is extremely effective in eliminating streaks.

That is, the coloring material 1405 not adsorbed on the fine particle surface 1403 and remaining in the ink is applied to the recording medium 14.
Since the ink penetrates both in the lateral direction and in the depth direction with respect to 01, a slight bleeding of the ink is formed in the peripheral portion IS. As described above, since the coloring material remains near the surface of the recording medium 1401 and minute bleeding of the ink is formed around the recording medium 1401, even in an image area where a large amount of ink is applied, such as a shadow portion or a solid portion, the white haze and There is little color unevenness and excellent color uniformity.

On the other hand, according to further studies by the present inventors,
When forming a recorded material in which images of different colors are provided adjacent to each other, a color material that does not react with fine particles is formed at a color boundary portion where different color images are adjacent to each other. It has been found that it is preferable to control ink bleeding in the peripheral portion to a higher degree in order to suppress bleeding. Then, when applying the aqueous ink and the liquid composition so as to contact in a liquid state on the recording medium,
By controlling the pH of the mixed liquid of the aqueous ink and the liquid composition formed when mixed on the recording medium, it becomes possible to control the minute bleeding, and thus a great effect is exerted on suppressing bleeding. I found out.

That is, the pH of the mixture of the aqueous ink and the liquid composition is determined by the pH at which the coloring material (dye) starts to aggregate.
If the pH value is controlled to be lower than that of the coloring material 1 in the mixed solution,
405 can be controlled. This is considered to be one of the reasons that the present embodiment has the above-described effect. More specifically, among the coloring materials 1405 in the ink applied on the recording medium 1401, the fine particles 14
What is not involved in the reaction with 03 is a change in the properties of the solvent due to the mixing of the ink and the liquid composition, for example,
Aggregates 1411 of the coloring material are formed by the pH change. As described above, the aggregate of the coloring material itself is not preferable in terms of color development. However, in the present embodiment, the presence of the aggregate does not significantly deteriorate the color development of the image. Although the reason is not clear, as shown in FIG. 14, the color material aggregates 1411 are present in the gaps between the fine particles adsorbing or binding the color material in a monomolecular state. Is faster than that of the coloring material adsorbing or binding to the surface of the fine particles in a monomolecular state, and the agglomerates of the coloring materials are relatively large in the lower part of the colored portion constituting the image. It is presumed that there is a tendency.

FIGS. 15 (1) to 15 (4) are a schematic sectional view of a coloring section 1500 and a schematic view for explaining a forming process thereof according to an embodiment of the ink jet recording image forming method according to the present invention. 14, reference numeral 1501 denotes a portion mainly containing a reaction product of the ink and the liquid composition, for example, a reaction product of a coloring material and fine particles (hereinafter abbreviated as “reaction portion”), and corresponds to the main image portion IM in FIG. This is the part to do. Reference numeral 1502 denotes a portion (hereinafter, abbreviated as “ink outflow portion”) formed by the ink that has not substantially participated in the reaction with the liquid composition flowing out to the periphery of the reaction portion 1501. Corresponds to the peripheral portion IS. The colored portion 1500 is formed, for example, as follows. In addition, 1 shown in FIG.
Reference numeral 505 schematically represents a gap generated between fibers of the recording medium.

First, a liquid composition 1506 reactive with the coloring material 1504 is applied as droplets to the recording medium 1503 (FIG. 15A), and as a result, a liquid composition pool 1507 is formed. (FIG. 15 (2)). The sump 15
07, the fine particles 150 near the fiber surface of the recording medium.
9 is physically or chemically adsorbed on the fiber surface of the recording medium. At this time, it is considered that the dispersion state becomes unstable and an aggregate 1511 of fine particles is formed. On the other hand, it is considered that the fine particles 1509 maintain the original dispersion state in the portion of the liquid pool 1507 farther from the fibers.

Next, the ink 1513 is applied as droplets to the recording medium 1503 (FIG. 15 (2)). As a result, first, at the interface between the ink 1513 and the liquid reservoir 1507, the coloring material 1504 is chemically adsorbed on the fine particles 1509. Since this reaction is a reaction between liquids (liquid-liquid reaction), the coloring material 1504 is considered to be uniformly adsorbed on the surface of the fine particles 1509 in a monomolecular state (FIG. 15 (3)-).
2). That is, it is presumed that the coloring materials do not agglomerate on the surface of the fine particles, or even if the agglomeration is slight. As a result, the coloring material 1 in a monomolecular state
Since a large number of fine particles having 504 adsorbed thereon are formed, and the coloring material can remain in a monomolecular state on the surface layer that most affects color development, a recorded image with high image density and high saturation is formed. . On the other hand, a part of the coloring material 1504 that does not participate in the reaction with the fine particles forms an aggregate 1517 of the coloring material due to a change in the characteristics of the liquid medium due to the mixing of the ink and the liquid composition, for example, a change in pH, and Precipitates in the mixture on the medium.

Next, the fine particles adsorbed by the coloring material 1504 are considered to be aggregated by the fine particles because the dispersion state becomes unstable (FIG. 15 (3) -2). That is, the aggregate 1515 formed here also holds the monomolecular color material inside. The aggregate 1515 forms a recorded image with high image density and high saturation. Further, a part of the unreacted coloring material 1504 diffuses in the liquid pool 1507 and is adsorbed on the surface of the unreacted fine particles 1509. As described above, since the reaction proceeds further inside the liquid pool 1507, an image having higher density and higher saturation is formed. It is considered that the aggregate 1511 of fine particles formed on the fiber surface of the recording medium described above has a role of suppressing the penetration of the liquid phase of the liquid pool 1507 into the recording medium. For this reason, in the liquid pool 1507, it becomes possible to mix more of the fine particles 1509 and the coloring material 1504 in the liquid composition whose permeation is suppressed. Accordingly, the probability of contact between the coloring material 1504 and the fine particles 1509 is increased, and the reaction proceeds relatively uniformly and sufficiently to form a more uniform image with high image density and high saturation.

The liquid composition 1506 is applied to the recording medium 15.
03 (FIG. 15 (1)) or the liquid pool 150
When the ink 1513 is applied to the ink 7 (see FIG.
(2)) The dispersion of the fine particles 1509 becomes unstable due to a change in the dispersion medium in which the fine particles 1509 are dispersed, and some of them cause aggregation between the fine particles 1509 before the coloring material 1504 is adsorbed. The change in the dispersion medium referred to here is a change generally observed when two or more different liquids are mixed, such as a pH of a liquid phase, a solid content concentration, a solvent composition, and a dissolved ion concentration. It is thought that when the liquid composition comes into contact with the recording medium or ink, these changes occur rapidly and in a complex manner, destroying the dispersion stability of the fine particles, and generating aggregates. Can be

These aggregates have the effect of filling voids,
It is presumed that the fine particles adsorbing the coloring material have an effect of remaining more near the surface of the recording medium. Some of the aggregates formed in the liquid pool 1507 are adsorbed on the recording medium, and some of them can move in the liquid phase (have fluidity). Is similar to the above-described reaction process between the coloring material and the fine particles, in which the coloring material is adsorbed in a monomolecular state on the surface of the fine particle aggregates to form a larger aggregate, which contributes to the improvement of the coloring property. It is.

It is considered that when the liquid phase permeates along the fiber, it moves together with the liquid phase, fills the voids, smoothes the surface of the recording medium, and contributes to the formation of a more uniform and high-density image.
It is clear from the results described below that an image with high color development can be obtained by the present invention, which is, as described above,
This is presumably because the coloring material was adsorbed to the fine particles or fine particle aggregates in a monomolecular state, and remained near the surface of the recording medium in that state. The coloring material is adsorbed in a monomolecular state, and the fine particles remaining on the surface of the recording medium are fixed on the surface of the recording medium. Thereby, the robustness is improved. Further, the aqueous ink and the liquid composition according to this embodiment are adjusted so that aggregation of the coloring material is started when a mixed liquid is formed by contacting the recording medium in a liquid-liquid state. Therefore, a coloring material aggregate 1517 is formed by a part of the coloring material, and it is possible to effectively prevent the unreacted coloring material from penetrating into the recording medium randomly.

Hereinafter, the pH dependence of the solubility of the dye will be described. FIG. 10 is a diagram illustrating the pH of the solution and the relative solubility of the dye at that pH value. As can be seen from FIG. 10, when the solution is gradually made acidic from pH 10, the dye that has been dissolved precipitates from around pH 7.5 (aggregation start pH). Further, as the pH is lowered, this dye is insolubilized at about pH 6.5.
In this experiment, a black dye “Direct Black-195” was used as a dye, the dye was dissolved in water, and the pH was adjusted by adding nitric acid to the solution and stirring for 10 minutes to obtain the above data. .

That is, if the pH of the mixture of the liquid composition and the ink mixed on the recording medium is controlled to an appropriate value equal to or lower than the pH at which the dye in the ink starts to aggregate, the desired dye can be obtained. It can be seen that the molecules can be insolubilized at the desired rate. That is, the dye molecules that are not adsorbed by the fine particles in the liquid composition can be appropriately restrained by controlling the pH and can be suppressed and controlled. Therefore, by adjusting the pH of the liquid mixture of the liquid composition and the ink, it is possible to achieve both the reduction of the bleeding occurring between different colors and the wide color reproduction area.

Further, since fine particle dye remains near the surface of the recording medium, white haze and color unevenness are small even in an image area where a large amount of ink is applied, such as a shadow portion or a solid portion.
Excellent color uniformity. As for the fixability, it is effective to incorporate a penetrant such as the surfactant into the ink so as to satisfy the desired ink penetration performance. That is, in this way, the dye molecules of the ink can be appropriately adsorbed and agglomerated, so that even if the penetrant is contained in the ink, the image density decreases, and the edge sharpness decreases.
A mechanism for fixing at high speed while suppressing the adverse effects such as a decrease in resolution can be realized.

Further, in the method for forming a colored portion on a recording medium according to the present invention, the liquid composition and the ink are applied onto the recording medium in such a manner that they come into contact with each other in a liquid state. A liquid phase reaction between the cationic fine particles and the coloring material occurs on the surface of the medium, and the coloring material can be extremely efficiently adsorbed on the surface of the fine particles. On the other hand, in order to achieve the same level of colorant adsorption as in the present invention in ink-jet coated paper, a large amount of cationic porous fine particles is required, and the formation of a thick ink receiving layer that covers the base paper is indispensable. Becomes For this reason, the coated paper leads to the result of impairing the texture of the base paper, but in the present invention, since the amount of fine particles used in the liquid composition can be reduced, the printed portion and the unprinted portion can be reduced without impairing the texture of the recording medium. Thus, an image can be formed without a sense of discomfort.

Hereinafter, the aqueous ink and the liquid composition which characterize the present invention will be described in detail. First, the definition of a cationic ink or an anionic ink in this specification will be described. It is well known in the art that when referring to the ionic properties of an ink, the ink itself is uncharged and neutral in itself. The anionic ink or cationic ink referred to here is a component in the ink, for example,
It refers to an ink in which a coloring material has an anionic group or a cationic group, and in the ink, these groups are adjusted to behave as an anionic group or a cationic group.

<Liquid Composition> The liquid composition will be described below. The liquid composition used in the present invention is characterized in that the surface is charged to the polarity opposite to the ionicity of the ink used therewith. Therefore, a cationic liquid composition or an anionic liquid composition is used depending on the ionicity of the ink.

[Cationic Liquid Composition] The cationic liquid composition includes, for example, a liquid containing an inorganic fine particle having a cationic group on its surface and an acid, wherein such a cationic fine particle is stably dispersed. Compositions. In the present invention, as the cationic liquid composition, for example, a pH adjusted to 2 to 7 containing an acid, or by including cationic fine particles having a high zeta potential, the zeta potential of the liquid composition is increased. A voltage of +5 to +90 mV can be suitably used.

(Regarding pH and Zeta Potential) The zeta potential of the liquid composition will be described. The basic principle of zeta potential will be described below. In general, in a system in which a solid is dispersed in a liquid, when there is free charge on the surface of a solid phase, a charged layer having an opposite charge appears in the liquid phase near the solid phase interface so as to maintain electrical neutrality. This is called an electric double layer, and the potential difference caused by the electric double layer is called zeta potential. When the zeta potential is positive, the surface of the fine particles is cationic, and when the zeta potential is negative, it is anionic.
Generally, it is said that the higher the absolute value, the stronger the electrostatic repulsion acting between the fine particles and the better the dispersibility. At the same time, it is considered that the ionicity of the surface of the fine particles is strong. That is, the higher the zeta potential of the cationic fine particles, the stronger the cationicity,
It can be said that the power to attract the anionic compound in the ink is strong.

Further, as a result of diligent studies by the present inventors, when a liquid composition having a zeta potential in the range of +5 to +90 mV is used, the colored portion formed on the recording medium has
It has been found that they exhibit particularly excellent coloring properties. The reason for this is not clear, but probably because the anionic compound is thinly and uniformly adsorbed on the surface of the fine particles without rapid aggregation of the anionic compound due to the moderate cationicity of the fine particles, the color material is huge. It is considered that a proper rake is hardly formed, and as a result, the original coloring properties of the coloring material are expressed in a better state. Further, in the cationic liquid composition used in the present invention, even after the anionic compound is adsorbed on the surface of the fine particles, the fine particles are in a dispersion unstable state while exhibiting a weak cationic property, so that the fine particles are contained in the recording medium. It is considered that the ink is easily adsorbed on the surface of an anionic cellulose fiber or the like existing in the recording medium, and is likely to remain near the surface of the recording medium.

As a result, it is considered that the following excellent effects can be obtained. That is, in the image area where the amount of applied ink is large, such as a shadow portion and a solid portion, white haze and color unevenness are small, and the color uniformity is excellent. In addition, since the anionic compound is adsorbed to the fine particles more efficiently than the coated paper to form a color, the applied amount of the cationic fine particles can be reduced, and particularly when printed on plain paper,
It does not impair the texture of the paper and has excellent scratch resistance in the printed area. Further, the zeta potential of the liquid composition is more preferably +10 to +85 mV, and within this range, the boundary between dots becomes less noticeable when solid printing is performed, and a good image with less streaks due to head scanning can be obtained. . Further, when the zeta potential is in the range of +15 to +65 mV, it is possible to obtain an image having extremely excellent coloring properties regardless of the type of paper.

The pH of the cationic liquid composition used in the present invention is preferably adjusted to a range of 2 to 7 at around 25 ° C. from the viewpoints of storage stability and adsorption of an anionic compound. Within this pH range, when mixed with the anionic ink, the stability of the anionic compound is not significantly reduced, so that strong aggregation of the anionic compounds does not occur, and the color of the recorded image does not increase. It is possible to effectively prevent the degree of the image from decreasing or becoming a dull image. When the content is within the above range, the dispersion state of the cationic fine particles is good, so that the storage stability of the liquid composition and the stability of ejection from the recording head can be maintained well. Furthermore, when mixed with ink, the anionic substance is sufficiently adsorbed on the surface of the cationic fine particles, so that excessive penetration of the coloring material into the recording medium is suppressed,
An ink jet recorded matter having excellent coloring properties can be obtained. More preferably, the pH is in the range of 3 to 6. In this range, the corrosion of the recording head due to long-term storage can be extremely effectively prevented, and the scratch resistance of the printed portion is further improved.

(Cationic Fine Particles) Next, the components constituting the cationic liquid composition of the present invention will be described. In order to achieve the above-mentioned effects, the cationic fine particles mentioned as the first component require that the surface of the particles themselves exhibit cationicity in a state of being dispersed in the liquid composition. By making the surface cationic,
When mixed with an anionic ink, the anionic coloring material is quickly adsorbed on the particle surface, and excessive penetration of the coloring material into the recording medium is suppressed, so that an inkjet recorded matter having a sufficient image density can be obtained. can get. On the other hand, when the surface of the fine particles is not cationic and is present separately from the water-soluble cationic water-soluble metal salt in the liquid composition, the color is mainly focused on the cationic compound. Since the materials are agglomerated and the coloring properties of the coloring materials themselves are impaired, it is difficult to achieve coloring properties comparable to those of coated ink jet paper.
Therefore, the fine particles used in the liquid composition of the present invention need to have a cationic surface, but not only fine particles that are essentially cationic, but also electrostatically anionic or neutral in nature. Even if there are certain fine particles, any fine particles whose surface has been cationized by the treatment can be used.

Specific examples of the cationic fine particles suitably used in the present invention are not particularly limited to material types.
The following inorganic fine particles, organic fine particles, inorganic-organic composite fine particles, and the like can be used. For example, as inorganic fine particles, cationized silica, alumina, alumina hydrate, titania, zirconia, boria,
Silica boria, ceria, magnesia, silica magnesia, calcium carbonate, magnesium carbonate, zinc oxide, hydrotalcite, and the like.Examples of organic fine particles include styrene acrylic and acrylate copolymers,
Methacrylic acid ester copolymers, conjugated diene copolymers such as SBR latex, cationic emulsions and latexes of vinyl copolymers such as ethylene vinyl acetate copolymer, and cationic modified products such as melamine beads and plastic pigments Is mentioned. Further, examples of the inorganic-organic composite fine particles include inorganic fine particles having primary, secondary and tertiary amine salt type functional groups on the surface.

The above-mentioned cationic fine particles used in the present invention may have an average particle diameter measured by a dynamic light scattering method from the viewpoints of color development after printing, color uniformity, storage stability and the like. Is preferably in the range of 0.005 to 1 μm. Within this range, excessive penetration into the inside of the recording medium can be effectively prevented, and a decrease in color developability and color uniformity can be suppressed. In addition, sedimentation of the cationic fine particles in the liquid composition is suppressed, and a decrease in the storage stability of the liquid composition can be effectively prevented. More preferably, the average particle diameter is in the range of 0.01 to 0.8 μm, and if such fine particles are used, the abrasion resistance of the image after printing on the recording medium and the texture of the recorded matter are reduced. It becomes particularly preferable.

The content of the cationic fine particles as described above in the liquid composition used in the present invention may be appropriately determined according to the kind of the substance to be used. The range of -40% by mass is a preferable range for achieving the object of the present invention, more preferably 1-30% by mass, and further preferably 3-15% by mass. Within such a range, an image with excellent color development can be stably obtained regardless of the type of paper, and the storage stability and ejection stability of the liquid composition are particularly excellent.

(Acid) As described above, the cationic liquid composition used in the present invention contains an acid and has a pH of 2 to 7.
It is preferable that the acid used at this time ionizes the surface of the cationic fine particles and increases the surface potential, thereby improving the dispersion stability of the fine particles in the liquid, It plays a role in improving the adsorptivity of the anionic compound in the ink and adjusting the viscosity of the liquid composition.
The acid preferably used in the present invention is not particularly limited as long as the desired pH, zeta potential, and physical properties such as fine particle dispersibility can be obtained in combination with the cationic fine particles to be used. It can be freely selected from organic acids and used.

Specifically, examples of the inorganic acid include hydrochloric acid, sulfuric acid, sulfurous acid, nitric acid, nitrous acid, phosphoric acid, boric acid, and carbonic acid. Examples of the organic acid include carboxylic acid such as those described below. And sulfonic acids and amino acids. As the carboxylic acid, for example, formic acid, acetic acid, chloroacetic acid, dichloroacetic acid, trichloroacetic acid, fluoroacetic acid,
Trimethylacetic acid, methoxyacetic acid, mercaptoacetic acid, glycolic acid, propionic acid, butyric acid, valeric acid, caproic acid,
Caprylic acid, cabric acid, lauric acid, myristic acid,
Palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, cyclohexanecarboxylic acid, phenylacetic acid, benzoic acid, o-toluic acid, m-toluic acid, p
-Toluic acid, o-chlorobenzoic acid, m-chlorobenzoic acid, p-chlorobenzoic acid, o-bromobenzoic acid, m-bromobenzoic acid, p-bromobenzoic acid, o-nitrobenzoic acid, m-nitrobenzoic acid Acid, p-nitrobenzoic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, tartaric acid, maleic acid, fumaric acid, citric acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, p-hydroxybenzoic acid , Anthranilic acid, m-aminobenzoic acid, p
-Aminobenzoic acid, o-methoxybenzoic acid, m-methoxybenzoic acid, p-methoxybenzoic acid and the like.
Examples of the sulfonic acid include benzenesulfonic acid, methylbenzenesulfonic acid, ethylbenzenesulfonic acid, dodecylbenzenesulfonic acid, 2,4,6-trimethylbenzenesulfonic acid, 2,4-dimethylbenzenesulfonic acid, and 5-sulfosulfonic acid. Salicylic acid, 1-sulfonaphthalene, 2-sulfonaphthalene, hexanesulfonic acid, octanesulfonic acid, dodecanesulfonic acid and the like can be mentioned. As amino acids, glycine, alanine, valine, α-aminobutyric acid, γ-aminobutyric acid, β-alanine,
Examples include taurine, serine, ε-amino-n-caproic acid, leucine, norleucine, phenylalanine and the like.

In the liquid composition used in the present invention, these can be used alone or in combination of two or more. Among these, the primary dissociation constant p in water
An acid having a ka of 5 or less can be suitably used because it is particularly excellent in the dispersion stability of the cationic fine particles and the adsorptivity of the anionic compound. As such, specifically, hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, acetic acid, formic acid, oxalic acid,
Lactic acid, citric acid, maleic acid, malonic acid and the like can be mentioned.

In the liquid composition used in the present invention, the mixing ratio of the cationic fine particles and the acid in the liquid composition is 200: 1 to 5: 1, more preferably 150: 1, based on weight.
It is particularly preferable that the ratio be in the range of 1 to 8: 1 in order to improve the dispersion stability of the cationic fine particles and to improve the adsorption of the anionic compound contained in the ink to the fine particle surfaces.

(Other components) Next, other components constituting the cationic liquid composition will be specifically described. The cationic liquid composition used in the present invention contains the above-mentioned cationic fine particles as an essential component, preferably contains the above-mentioned acid, and, in addition, usually contains water as a liquid medium. Organic solvents and other additives. As the water-soluble organic solvent used at this time, for example, amides such as dimethylformamide, dimethylacetamide, ketones such as acetone, ethers such as tetrahydrofuran and dioxane, polyethylene glycol, polyalkylene glycols such as polypropylene glycol, Alkylene glycols such as ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol, ethylene glycol methyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl Lower alkyl ethers of polyhydric alcohols such as ethers, ethanol,
In addition to monohydric alcohols such as isopropyl alcohol, n-butyl alcohol and isobutyl alcohol, glycerin, N-methyl-2-pyrrolidone, 1,3-dimethyl-
Examples include imidazolidinone, triethanolamine, sulfolane, dimethyl sulfoxide and the like. The content of the water-soluble organic solvent is not particularly limited. For example, 5 to 60% by weight of the total weight of the liquid composition,
40% by weight is a suitable range.

The liquid composition used in the present invention may further contain, if necessary, a viscosity modifier, a pH regulator, a preservative, various surfactants, an antioxidant and an evaporation promoter, An additive such as a cationic cationic compound or a binder resin may be appropriately blended. The selection of the surfactant is particularly important in adjusting the permeability of the liquid composition into the recording medium. The water-soluble cationic compound can be freely selected and added within a range that does not inhibit the effects of the present invention, for the purpose of further imparting cationicity to the liquid composition.

Examples of the water-soluble cationic compound include, for example, polyallylamine, polyamine sulfone, polyvinylamine, chitosan, and neutralized or partially neutralized products thereof with an acid such as hydrochloric acid or acetic acid. Compounds in which a part of the nonionic compound of the molecule is cationized, for example, a copolymer of vinylpyrrolidone and quaternary salt of aminoalkyl alkylate, a copolymer of acrylamide and quaternary salt of aminomethylacrylamide, etc. First grade,
One or more selected from secondary and tertiary amine salt type compounds and amino acid type amphoteric compounds can be used. Further, the binder resin, for the purpose of further improving the abrasion resistance of the cationic fine particles, can be used in combination within a range that does not impair the texture of the recording medium and the storage stability and ejection stability of the liquid composition. , Water-soluble polymers, emulsions, latexes and the like can be freely selected and used.

(Surface Tension of Cationic Liquid Composition) The liquid composition used in the present invention is preferably colorless or white, but may be toned according to the color of the recording medium. Further, as a preferable range of various physical properties of the liquid composition as described above, the surface tension is set to 10 to 60 mN / m.
(Dyn / cm), more preferably 10 to 40 mN / m
(Dyn / cm) and a viscosity of 1 to 30 mPa · s (c
P).

(Coloring Material Aggregation Function of Cationic Liquid Composition) The pH of the cationic liquid composition used in the present invention
Is preferably 2 or more at around 25 ° C. from the viewpoint of storage stability and adsorptivity of anionic compounds as described above. That is, when the pH is 2 or more, the stability of the anionic compound in the ink does not significantly decrease when mixed with the ink, so that the fine particles in the liquid composition maintain a monomolecular state. It is possible to avoid the occurrence of strong aggregation between anionic compounds before they are adsorbed while performing. On the other hand, the upper limit of the pH is not particularly limited, but the dye molecules that are not adsorbed by the fine particles penetrate or diffuse freely on the recording medium or inside the recording medium, and in order to suppress bleeding or bleeding of an image. It is effective to aggregate unadsorbed dye molecules. Therefore, in the present invention, the pH of the mixed liquid obtained by mixing the liquid composition and the aqueous ink to be used on the recording medium is not less than pH 2 at which rapid aggregation does not occur, and not more than the pH at which the dye starts to aggregate. It is preferable to control the pH of the solution. This makes it possible to reduce bleeding and achieve color reproduction comparable to ink-jet coated paper, while recording on plain paper.

Further, by suppressing the pH of the liquid composition, it is possible to suppress the deterioration of the dispersibility of the cationic fine particles. Therefore,
The storage stability of the liquid composition and the stability of ejection from the recording head can be improved. Then, in a mixed liquid of the anionic ink and the cationic liquid composition, an anionic ink and a cationic liquid composition capable of causing a pH change such that aggregation of the anionic dye in the anionic ink occurs. Examples of the specific combinations include the following examples.

(Anionic ink: pH = 9.8)-Direct Black 195 2.5 parts-2-Pyrrolidone 10 parts-Glycerin 5 parts-Isopropyl alcohol 4 parts-NaOH 0.4 part-Water balance (100 in total) Part)

(Cationic liquid composition: pH = 3.5) 7.5 parts of glycerin 7.5 parts of diethylene glycol 10 parts of alumina hydrate 3 parts of acetic acid The remaining part of water (100 parts in total)

When the anionic ink and the cationic ink are mixed at a weight ratio of 1: 1, the pH of the mixed liquid is adjusted to pH 6.5 to 6.5 at which direct black 195 shown in FIG. Changes to around 7.5,
Along with the adsorption or binding of the direct black 195 to the alumina hydrate surface in a monomolecular state, mild aggregation of the direct black 195 is observed.

[Anionic liquid composition] The anionic liquid composition used in the present invention contains fine particles having an anionic group on the surface as an essential component, and that the fine particles are stably dispersed. Although it is a feature, it is more preferable to use a substance containing a base and having a pH adjusted to 7 to 12, or a substance having a zeta potential of -5 to -90 mV.

(Regarding pH and Zeta Potential) As a result of extensive studies by the present inventors, the zeta potential of the liquid composition was -5.
Those having a range of -90 mV found that the cationic compound in the ink was particularly efficiently adsorbed on the surface of the anionic fine particles, and exhibited particularly excellent coloring properties on the recording medium. The reason is not clear, but probably, as in the case of the cationic liquid composition described above, because the anionicity of the fine particles is moderate, the rapid aggregation of the cationic compound in the ink does not occur, It is considered that the coloring material does not form a huge lake by adsorbing thinly and uniformly on the surface of the fine particles, so that the original coloring characteristics of the coloring material are better exhibited. Further, in the anionic liquid composition used in the present invention, the dispersion becomes unstable after the cationic compound is adsorbed on the surface of the fine particles, and the fine particles aggregate due to a change in concentration when the solvent component permeates on the recording medium. Therefore, it is considered that it is easy to remain near the surface.

As a result, it is considered that the following excellent effects can be obtained. In other words, the color development characteristics are as excellent as those of coated ink-jet paper, and there is little white haze and color unevenness in an image area where a large amount of ink is applied, such as a shadow portion or a solid portion, and the color uniformity is excellent. In addition, the cationic compound is adsorbed to the surface of the fine particles very efficiently as compared with the coated paper, and the color is formed.
In particular, when printing is performed on plain paper, the texture of the paper is maintained, and the scratch resistance of the printed portion is improved. More preferably, the zeta potential is -10 to -85 mV. In the liquid composition in this range, the anionic fine particles having the cationic compound adsorbed on the surface thereof are appropriately spread on the recording medium, and the dots between the dots when solid printing are performed. Is less noticeable, and a good image with less streak by head scanning can be obtained. Further, in the range of -15 to -65 mV, it is possible to obtain an image having extremely excellent coloring properties regardless of the type of paper.

The pH of the anionic liquid composition used in the present invention is preferably in the range of 7 to 12 at about 25 ° C. from the viewpoints of storage stability and adsorption of the cationic compound. Within this pH range, the stability of the cationic compound does not significantly decrease when mixed with the cationic ink, so that strong aggregation of the cationic compounds does not occur, and the saturation of the recorded image is reduced. Can be effectively prevented from dropping or becoming a dull image. In addition, when the content is within the above range, the dispersibility of the anionic fine particles is good, so that the storage stability of the liquid composition and the stability of ejection from the recording head can be maintained satisfactorily. Further, when mixed with the ink, the cationic substance is sufficiently adsorbed on the surface of the anionic fine particles to suppress excessive penetration of the coloring material into the recording medium, thereby obtaining an ink jet recorded matter having excellent coloring properties. Can be The more preferable pH range of the liquid composition is from 8 to 11. When the pH is within this range, corrosion of the recording head due to long-term storage can be extremely effectively prevented, and the scratch resistance of the printing portion is further improved. improves.

(Anionic Fine Particles) Next, the components constituting the anionic liquid composition of the present invention will be described. In order to achieve the above-mentioned effects, the anionic fine particles mentioned as the first component preferably have an anionic surface when dispersed in the liquid composition. When mixed with a cationic ink by making the surface anionic, the cationic coloring material can be adsorbed on the particle surface, and the coloring material is suppressed from excessively penetrating into the recording medium. An ink jet recorded matter having an image density can be obtained. On the other hand, when the surface of the fine particles is not anionic and the liquid composition is present separately from the water-soluble anionic compound, the coloring material aggregates around the anionic compound. In addition, since the coloring properties of the coloring material itself are impaired, it is difficult to achieve coloring properties comparable to those of inkjet coated paper. Therefore, the fine particles used in the liquid composition of the present invention need to have an anionically charged surface. Even neutral fine particles can be used as long as the fine particles have a surface anionized by the treatment.

Specific examples of the anionic fine particles suitably used in the present invention are not particularly limited to the material type.
The following inorganic fine particles, organic fine particles, inorganic-organic composite fine particles, and the like can be used. For example, examples of the inorganic fine particles include anionized silica, titania, zirconia, boria, silica boria, ceria, magnesia, silica magnesia, calcium carbonate, magnesium carbonate, and zinc oxide. , Styrene acrylic and acrylate copolymers, methacrylate copolymers, conjugated diene-based copolymers such as SBR latex, and anionic emulsions and latexes of vinyl-based copolymers such as ethylene-vinyl acetate copolymer, Alternatively, an anion-modified product such as melamine beads or plastic pigment may be used.
Examples of the inorganic-organic composite fine particles include, for example, inorganic fine particles having a functional group exhibiting anionic properties in water on the surface.

The anionic fine particles used in the present invention are, similarly to the cationic fine particles described above, from the viewpoint of dynamic light scattering from the viewpoint of color development after printing, color uniformity, and storage stability. The average particle diameter measured by the method is 0.00
Those having a range of 5 to 1 μm are preferred. More preferably, the average particle diameter is in the range of 0.01 to 0.8 μm, and if such fine particles are used, the abrasion resistance and texture after printing on the recording medium become particularly preferable. .

The content of the anionic fine particles in the liquid composition as described above depends on the type of the substance to be used.
The optimum range may be determined as appropriate, but is not more than 0.
The range of 1 to 40% by weight is a preferable range for achieving the object of the present invention, more preferably 1 to 30% by weight, and further preferably 3 to 15% by weight. Within such a range, an image with excellent color development can be stably obtained regardless of the type of paper, and the storage stability and ejection stability of the liquid composition are particularly excellent.

(Base) As described above, the anionic liquid composition used in the present invention contains a base and has a pH of 7 or less.
It is preferable that the base used at this time ionizes the surface of the anionic fine particles and increases the surface potential, thereby improving the dispersion stability in the liquid and improving the dispersion in the ink. Plays a role in improving the adsorptivity of the cationic compound and adjusting the viscosity of the liquid composition. The base suitably used in the present invention is not particularly limited as long as physical properties such as desired pH, zeta potential, and fine particle dispersibility can be obtained when combined with the anionic fine particles to be used. It can be used by freely selecting from various inorganic compounds and organic compounds.

Specifically, for example, sodium hydroxide,
Lithium hydroxide, sodium carbonate, ammonium carbonate,
Ammonia, sodium acetate, ammonium acetate, morpholine, monoethanolamine, diethanolamine,
Triethanolamine, ethyl monoethanolamine,
Alkanolamines such as normal butyl monoethanolamine, dimethylethanolamine, diethylethanolamine, ethyldiethanolamine, normal butyldiethanolamine, dinormalbutylethanolamine, monoisopropanolamine, diisopropanolamine, and triisopropanolamine can be used. Among them, a base having a primary dissociation constant pkb of 5 or less in water is particularly preferably used because it is particularly excellent in dispersion stability of anionic fine particles and adsorptivity of a cationic compound.

The mixing ratio between the anionic fine particles and the base in the liquid composition used in the present invention is 200: 1 by weight.
A range of from 5: 1 to 5: 1, more preferably from 150: 1 to 8: 1, is preferable because the dispersion stability of the anionic fine particles and the adsorptivity of the cationic compound to the surface of the fine particles are excellent.

(Other Components) Next, other components constituting the anionic liquid composition will be specifically described. The anionic liquid composition used in the present invention contains the above-mentioned anionic fine particles as an essential component, preferably contains the above-mentioned base, and, in addition, usually contains water as a liquid medium, and further contains Water-soluble organic solvents and other additives, for example, viscosity additives, pH regulators, preservatives, various surfactants, antioxidants and evaporation promoters, additives such as water-soluble anionic compounds and binder resins are appropriately compounded. It does not matter.

(Surface Tension of Anionic Liquid Composition) The liquid composition used in the present invention is more preferably colorless or white, but may be toned in accordance with the color of the recording medium. Furthermore, as a preferable range of various physical properties of the liquid composition as described above, the surface tension is set to 10 to 60 mN / m (d
yn / cm), more preferably 10 to 40 mN / m (d
yn / cm) and the viscosity is 1 to 30 mPa · s (cP)
It is what it was.

(Coloring Material Aggregation Function of Anionic Liquid Composition) The anionic liquid composition used in the present invention has the following two functions when mixed with ink on a recording medium. One is a function in which the fine particles contained in the liquid composition adsorb a cationic compound such as a dye molecule, which is a coloring material of the ink, with an appropriate adsorbing force. This is a function of setting the pH of the liquid to the aggregation pH value of the dye coloring material described above. Therefore, at least the surface of the fine particles themselves contained in the liquid composition preferably contains anionic fine particles and a base, and the zeta potential of the liquid composition is in the range of -5 to -90 mV. Preferably, it is adjusted.

<Aqueous Ink> [Anionic Ink] Next, the aqueous anionic ink constituting the ink set of the present invention in combination with the cationic liquid composition described above will be described. The ink set referred to here is a combination of the cationic liquid composition having the configuration as described above and at least one or more anionic inks.
Further, in the present specification, a combination of at least one or more inks except for the liquid composition from the ink set,
It is called an ink subset. The anionic ink used in the present invention can be prepared by incorporating an anionic compound. Is obtained by using an anionic compound in combination. These anionic inks used in the present invention further include a liquid medium such as water and a water-soluble organic solvent, and other components such as a viscosity adjuster, a pH adjuster, a preservative, and a surfactant. , An antioxidant and the like are included as necessary. Hereinafter, each component of these inks will be described.

(Water-soluble dye) The water-soluble dye having an anionic group used in the present invention includes, for example, water-soluble acid dyes, direct dyes, and reactive dyes described in Color Index. If it is, there is no particular limitation. In addition, there is no particular limitation on those not described in the color index as long as they have an anionic group such as a sulfone group and a carboxyl group.
Further, a water-soluble dye having a carboxyl group as an anionic group is preferably used because aggregation due to a change in pH is particularly likely to occur effectively. The water-soluble dyes mentioned here include those having a pH dependence of solubility.

(Pigment) As another form of the aqueous anionic ink, a pigment is used as a coloring material in place of the water-soluble dye having an anionic group as described above, and an anionic compound is used together with the pigment. The ink may include a liquid medium such as water and a water-soluble organic solvent, and other components such as a viscosity adjuster, a pH adjuster, a preservative, a surfactant, and an antioxidant, as necessary. Here, the anionic compound may be a dispersant for the pigment, or when the dispersant for the pigment is not anionic, an anionic compound other than the dispersant may be added. Of course, even when the dispersant is an anionic compound, the dispersant may further contain another anionic compound.

The pigment which can be used in the present invention is not particularly limited. For example, the following pigments can be suitably used. First, the carbon black used for the black pigment ink is a carbon black manufactured by a furnace method or a channel method, and has a primary particle size of 15 to 40.
Millimicron, specific surface area by BET method is 50-30
0 square meters / g, DBP oil absorption is 40-150m
1/100 g, volatile content 0.5-10%, pH value 2
Those having 9 are preferred. As such,
For example, no. 2300, no. 900, MCF88,
No. 40, no. 52, MA7, MA8, No. 22
00B (all made by Mitsubishi Kasei), RAVEN1255 (made by Columbia), REGAL400R, REGAL660
R, MOGUL L (above, made by Cabot), Colo
r Black FW1, Color Black F
W18, Color Black S170, Colo
r Black S150, Printex 35, P
Commercial products such as printx U (all manufactured by Degussa) can be used. Further, a prototype newly manufactured for the present invention may be used.

Examples of the pigment used in the yellow ink include C.I. I. Pigment Yellow
1, C.I. I. Pigment Yellow 2, C.I.
I. Pigment Yellow 3, C.I. I. Pi
gment Yellow 13, C.I. I. Pigme
nt Yellow 16, C.I. I. PigmentY
yellow 83 and the like.

Examples of the pigment used as the magenta ink include C.I. I. Pigment Red 5,
C. I. Pigment Red 7, C.I. I. Pig
Ment Red 12, C.I. I. Pigment R
ed 48 (Ca), C.I. I. Pigment Red
48 (Mn), C.I. I. Pigment Red 57
(Ca), C.I. I. Pigment Red 112,
C. I. Pigment Red 122 and the like.

Examples of the pigment used as the cyan ink include C.I. I. Pigment Blue 1,
C. I. Pigment Blue 2, C.I. I. Pi
gment Blue 3, C.I. I. Pigment
Blue 15, 3, C.I. I. Pigment Blu
e16, C.I. I. Pigment Blue 22,
C. I. Vat Blue 4, C.I. I. Vat Bl
ue 6 and the like. In addition, any color materials newly manufactured for the present invention can be used.

(Pigment Dispersant) As a pigment dispersant which can be used in the ink used in the present invention, a water-soluble dispersant having a function of stably dispersing the pigment in water or an aqueous medium due to the presence of an anionic group. Any resin can be used. In particular, a weight average molecular weight of 1,000
Those having a range of up to 30,000 are preferred. More preferably, it is in the range of 3,000 to 15,000. Specifically, for example, hydrophobic monomers such as styrene, styrene derivatives, vinyl naphthalene, vinyl naphthalene derivatives, aliphatic alcohol esters of α, β-ethylenically unsaturated carboxylic acids, or acrylic acid, acrylic acid derivatives , Maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, block copolymers comprising two or more monomers selected from fumaric acid derivatives, graft copolymers, or random copolymers, In addition, these salts and the like can be mentioned. These resins are alkali-soluble resins that are soluble in an aqueous solution in which a base is dissolved.

Further, a homopolymer comprising a hydrophilic monomer or a salt thereof may be used. Also, polyvinyl alcohol,
Water-soluble resins such as carboxymethylcellulose and condensates of naphthalenesulfonic acid formaldehyde can also be used. However, when an alkali-soluble resin is used, there is an advantage that the viscosity of the dispersion can be reduced and the dispersion is easy. The water-soluble resin is preferably used in a range of 0.1 to 5% by weight based on the total amount of the ink.

The pigment ink which can be used in the present invention is constituted by dispersing or dissolving the pigment and the water-soluble resin as described above in a water-soluble medium. An aqueous medium suitable for the pigment-based ink that can be used in the present invention is a mixed solvent of water and a water-soluble organic solvent. The water is not general water containing various ions, but deionized water (deionized water). ) Is preferred.

When the dispersant is not an anionic polymer, it is preferable to further add an anionic compound to the ink containing the pigment described above. Examples of the anionic compound suitably used in the present invention include, in addition to high molecular substances such as the alkali-soluble resins described in the section of the pigment dispersant, low molecular anionic surfactants as described below. .

Specific examples of the low molecular weight anionic surfactant include, for example, disodium lauryl sulfosuccinate, disodium polyoxyethylene lauroylethanolamide ester of sulfosuccinate, disodium polyoxyethylene alkyl sulfosuccinate, and carboxylated polysodium. Oxyethylene lauryl ether sodium salt, carboxylated polyoxyethylene lauryl ether sodium salt, carboxylated polyoxyethylene tridecyl ether sodium salt, polyoxyethylene lauryl ether sodium sulfate, polyoxyethylene lauryl ether triethanolamine sulfate, polyoxyethylene alkyl Sodium ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium alkyl sulfate, Le sulfate triethanolamine, and the like, but is not limited thereto. The preferred amount of the anionic substance as described above is in the range of 0.05 to 10% by weight based on the total amount of the ink.
More preferably, it is 0.05 to 5% by weight.

(Self-dispersion type pigment) As a pigment which can be used for an anionic ink, a self-dispersion type pigment which can be dispersed in water or an aqueous medium without using a dispersant can also be used. . The self-dispersion type pigment has at least one kind of anionic hydrophilic group bonded directly or via another atomic group to the surface of the pigment. As the anionic hydrophilic group, for example, at least one selected from the following hydrophilic groups, and further, another atomic group is an alkyl group having 1 to 12 carbon atoms, Those which are a phenyl group which may have a group or a naphthyl group which may have a substituent are mentioned.

The carbon black charged anionically by introducing a hydrophilic group onto the surface of the carbon black has excellent water dispersibility due to repulsion of ions. Even if no dispersant is added, a stable dispersion state can be maintained.

(Other Additives of Ink) In addition to the above-mentioned components, a surfactant, an antifoaming agent, a preservative, and the like are added as needed in order to obtain an ink having desired physical properties. Further, a commercially available water-soluble dye or the like can be added.

Examples of the surfactant include anionic surfactants such as fatty acid salts, higher alcohol sulfates, liquid fatty oil sulfates, alkylallyl sulfonates, polyoxyethylene alkyl ethers, and polyoxyethylene alkyl esters. , Polyoxyethylene sorbitan alkyl esters, non-ionic surfactants such as acetylene alcohol and acetylene glycol, and one or more of these can be appropriately selected and used. The amount used depends on the amount of the dispersant added,
Desirably, the content is 0.01 to 5% by weight based on the total amount of the ink.
At this time, the surface tension of the ink is 30 mN / m (dyn / c
It is preferable to determine the amount of the activator to be added so as to satisfy m) or more. This is because, in the ink jet recording system used in the present invention, generation of print distortion (deviation of the impact point of ink droplets) due to the wetting of the nozzle tip can be effectively suppressed.

As a method for preparing a pigment-based ink as described above, first, a pigment is added to an aqueous solution containing at least a dispersing resin and water, and the mixture is stirred. Then, if necessary, centrifugation is performed to obtain a desired dispersion. Next, the above-mentioned components may be further added to the dispersion and stirred to form an ink.

When an alkali-soluble resin is used, it is necessary to add a base to dissolve the resin. At this time, the amount of the amine or the base for dissolving the resin must be at least one time the amount of the amine or the base obtained by calculation from the acid value of the resin. The amount of the amine or the base can be calculated by the following equation.

Further, if the premixing is carried out for 30 minutes or more before the dispersion treatment of the aqueous solution containing the pigment, the dispersion efficiency is improved. This premixing operation improves the wettability of the pigment surface and promotes the adsorption of the dispersant on the pigment surface.

The bases to be added to the dispersion when the alkali-soluble resin is used include, for example, organic amines such as monoethanolamine, diethanolamine, triethanolamine, amine methylpropanol and ammonia, and potassium hydroxide. It is preferable to use an inorganic base such as sodium hydroxide.

On the other hand, the dispersing machine used for preparing the pigment ink may be any commonly used dispersing machine, and examples thereof include a ball mill and a sand mill.
Among them, a high-speed sand mill is preferable, for example,
Examples thereof include a super mill, a sand grinder, a bead mill, an agitator mill, a Glen mill, a dyno mill, a pearl mill, a Kobol mill (all trade names) and the like.

The ink used in the present invention may contain, if necessary, a water-soluble organic solvent, a surfactant,
Additives such as an H adjuster, a rust inhibitor, a fungicide, an antioxidant, an evaporation accelerator, a chelating agent, and a water-soluble polymer may be added.

The anionic ink used in the present invention is constituted by dissolving or dispersing the above-mentioned coloring materials in a liquid medium. The liquid medium used at this time is preferably a mixture of water and the following water-soluble organic solvents. Specific water-soluble organic solvents include:
For example, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-
Alkyl alcohols having 1 to 4 carbon atoms such as butyl alcohol, amides such as dimethylformamide and dimethylacetamide, ketones such as acetone, ethers such as tetrahydrofuran and dioxane, and polyalkylene glycols such as polyethylene glycol and polypropylene glycolicol. , Ethylene glycol, propylene glycol, butylene glycol, triethylene glycol,
1,2,6-hexanetriol, thiodiglycol,
Lower alkyl ethers of polyhydric alcohols such as alkylene glycols having an alkylene group containing 2 to 6 carbon atoms such as hexylene glycol and diethylene glycol, glycerin, ethylene glycol monomethyl (or ethyl) ether, and diethylene glycol monomethyl (or ethyl) ether , N-methyl-2-pyrrolidone,
1,3-dimethyl-2-imidazolidinone, sulfolane, dimethylsulfoxide, 2-pyrrolidone, ε
And cyclic amide compounds such as caprolactam and imide compounds such as succinimide.

In general, the content of the water-soluble organic solvent is preferably from 1% to 40% by weight, more preferably from 3% to 30%, based on the total weight of the ink.
When the content of water in the ink is in the range of 30 to 95% by weight, the solubility of the coloring material is good, the increase in the viscosity of the ink can be suppressed, and This is preferable because the fixing property can be sufficiently satisfied.

The anionic ink used in the present invention can be used as a general water-soluble writing instrument, but is particularly suitable when applied to an ink jet recording method of a type in which the ink is ejected by a bubbling phenomenon of the ink by thermal energy. There is a feature that the ejection becomes extremely stable and no generation of satellite dots or the like occurs. However, in this case, the thermal properties (for example, specific heat, thermal expansion coefficient, and thermal conductivity) may be adjusted.

[Cationic Ink] Next, the aqueous cationic ink constituting the ink set of the present invention in combination with the anionic liquid composition described above will be described. The ink set referred to here is a combination of the anionic liquid composition having the configuration described above and at least one or more cationic inks. Further, in this specification, a combination of at least one or more types of ink obtained by removing the liquid composition from the ink set is referred to as an ink subset. The cationic ink used in the present invention can be prepared by incorporating a cationic compound. Can be obtained by using a cationic compound in combination. The cationic ink used in the present invention includes, in addition to the above-described components, a liquid medium including water, a water-soluble organic solvent, and other components such as a viscosity adjuster, a pH adjuster, and a preservative. Agents, surfactants, antioxidants and the like are included as necessary. Hereinafter, each component of these inks will be described.

(Water-soluble dye) The water-soluble dye having a cationic group used in the present invention is not particularly limited as long as it is a cationic water-soluble dye described in, for example, Color Index. Can be used without. In addition, there is no particular limitation on those not described in the color index as long as they have a cationic group. In addition, among the water-soluble dyes mentioned here, the solubility p
Those having H dependency are also included.

(Pigment) As another form of the ink used in the present invention, a pigment is used instead of the above-mentioned water-soluble dye having a cationic group as a coloring material, and a cationic compound is used in combination with the pigment. Further, water, a liquid medium such as a water-soluble organic solvent, and other components, for example, a viscosity modifier, pH
It comprises a regulator, a preservative, a surfactant, an antioxidant and the like as necessary. At this time, the cationic compound used in combination may be a pigment dispersant, or if the pigment dispersant is not cationic, a cationic compound may be added separately from the dispersant. Of course, even when the dispersant is a cationic compound, another cationic compound may be further added. The pigment that can be used in the present invention is not particularly limited, and the pigments described above in the section of the anionic ink can be suitably used.

(Pigment Dispersant) As a pigment dispersant in the ink used in the present invention, any water-soluble resin having a function of stably dispersing the pigment in water or an aqueous medium due to the presence of a cationic group can be used. Anything can be used. As a specific example, what is necessary is just what is obtained by superposition | polymerization of a vinyl monomer, and at least one part of the obtained polymer has cationic property. Examples of the cationic monomer for constituting the cationic moiety include the following salts of tertiary amine monomers and quaternized compounds thereof.

N, N-dimethylaminoethyl methacrylate
[CH_Two= C (CH_Three) -COO-C_TwoH_FourN (C
H_Three)_Two], N, N-dimethylaminoethyl acrylate
[CH_Two= CH-COO-C_TwoH_FourN (CH_Three)_Two], N, N
-Dimethylaminopropyl methacrylate [CH_Two= C
(CH_Three) -COO-C_ThreeH₆N (CH_Three)_Two], N, N-dimension
Tylaminopropyl acrylate [CH_Two= CH-CO
OC_ThreeH₆N (CH_Three)_Two], N, N-dimethylacrylia
Mid [CH_Two= CH-CON (CH_Three)_Two], N, N-dimension
Tyl methacrylamide [CH_Two= C (CH_Three) -CON (C
H_Three)_Two], N, N-dimethylaminoethylacrylamido
C [CH_Two= CH-CONHC_TwoH_FourN (CH_Three)_Two], N,
N-dimethylaminoethyl methacrylamide [CH_Two=
C (CH_Three) -CONHC _TwoH_FourN (CH_Three)_Two], N, N-di
Methylaminopropylacrylamide [CH_Two= CH-
CONH-C_ThreeH₆N (CH_Three)_Two], N, N-dimethylamido
Propyl methacrylamide [CH_Two= C (CH_Three) -CO
NH-C_ThreeH₆N (CH_Three)_TwoAnd the like.

In the case of a tertiary amine, compounds for forming a salt include hydrochloric acid, sulfuric acid, and acetic acid. Compounds used for quaternization include methyl chloride, dimethyl sulfate, and benzyl chloride. And epichlorohydrin. Among them, methyl chloride, dimethyl sulfate and the like are particularly preferably used for preparing the pigment dispersant used in the present invention. The tertiary amine salt or the quaternary ammonium compound as described above behaves as a cation in water, and under neutralized conditions, acidity is a stable dissolution region. The content of these monomers in the copolymer is preferably in the range of 20 to 60% by weight.

Examples of other monomers used in the constitution of the polymer dispersant include acrylic acid esters having a hydroxy group, such as 2-hydroxyethyl methacrylate and acrylic acid esters having a long ethylene oxide chain in the side chain; Examples of hydrophobic monomers such as styrene monomers and water-soluble monomers that can be dissolved in water having a pH of about 7 include acrylamides, vinyl ethers, vinylpyrrolidones, vinylpyridines, and vinyloxazolines. As the hydrophobic monomer, styrene,
Hydrophobic monomers such as styrene derivatives, vinyl naphthalene, vinyl naphthalene derivatives, alkyl esters of (meth) acrylic acid, and acrylonitrile are used. In the polymer dispersant obtained by copolymerization, a water-soluble monomer is used to make the copolymer stably exist in an aqueous solution.
The hydrophobic monomer is used in an amount of 5 to 35% by weight and is used in an amount of 2 to increase the dispersing effect of the copolymer on the pigment.
It is preferable to use it in the range of 0 to 40% by weight.

(Self-dispersing Pigment) In the case of cationically charged carbon black, the hydrophilic group bonded directly or via another atomic group is at least one selected from the following quaternary ammonium groups. And a combination of the two. However, the present invention is not limited to these.

[0116]In the above formula, R is a linear or branched chain having 1 to 12 carbon atoms.
Alkyl group, substituted or unsubstituted phenyl group, or
Represents a substituted or unsubstituted naphthyl group. The above
For example, the cationic group of
If NO_Three ^-And CH _ThreeCOO^-Exists.

As a method for producing a cationically charged self-dispersible carbon black having a hydrophilic group bonded thereto as described above, for example, a method of bonding an N-ethylpyridyl group having the following structure is exemplified. As an example, there is a method of treating carbon black with 3-amino-N-ethylpyridinium bromide.

[0118]

The carbon black charged cationically by the introduction of a hydrophilic group on the surface of the carbon black has excellent water dispersibility due to repulsion of ions. In particular, it shows a stable dispersion state without adding a dispersant or the like.

(Surface Tension of Ink) Further, the above-mentioned aqueous ink used in the present invention has good matching with the ink jet head at the same time as the ink permeability of the printed matter recorded on plain paper or the like. In terms of the physical properties of the ink, the surface tension at 25 ° C. is 30 to 68 mN / m (dyn / cm), and the viscosity is 15 mPa · s (cP) or less, preferably 10 mPa
S (cP) or less, more preferably 5 mPa · s (c
P) It is desirable to adjust to the following.

(Concentration of Aqueous Ink) The weight concentration of the coloring material component contained in the anionic and cationic aqueous inks having the above-mentioned constitutions used in the present invention is determined by using an aqueous dye,
It is appropriately selected according to the type of the coloring material such as a pigment or a self-dispersing pigment, but it is in the range of 0.1 to 20% by weight, particularly 0.1 to 12% by weight based on the weight of the ink. Is preferred. When the weight concentration of these coloring material components is in the range of 0.3 to 7% by weight, the relationship between the concentration of the fine particles contained in the liquid composition and the concentration of the coloring material in the ink is reduced. , On a weight basis, for the fine particles 1 in the liquid composition,
When the color material is 1.2 or less, particularly 1.0 or less, the color developability of an image formed under ordinary two-liquid recording conditions is particularly excellent.

<Method of Forming a Colored Part on a Recording Medium> Next, a method of forming a colored part on a recording medium of the present invention will be described. The method of forming a colored portion on a recording medium of the present invention uses an ink set in which the liquid composition and the aqueous ink configured as described above are combined, and (i) applying the aqueous ink to the recording medium. And (ii) applying the liquid composition to the recording medium, wherein the aqueous ink and the liquid composition are liquid-liquid on the recording medium.
The method is characterized in that both droplets are ejected toward a recording medium and applied so that a state of contact in a liquid state is formed.

Hereinafter, a method of applying the liquid composition and the aqueous ink having the above-described structures to a recording medium will be described. In the method for forming a colored portion on a recording medium of the present invention, specifically, a liquid composition is applied to a colored portion forming region formed by ink on a recording medium, or to the colored portion forming region and its vicinity. Then, a state where the aqueous ink and the liquid composition are in contact with each other in a liquid-liquid state is formed on the recording medium. The term "colored portion forming region" as used herein refers to a region where ink dots adhere, and the vicinity of the colored portion forming region refers to a region approximately 1 to 5 dots apart from the region where ink dots adhere. Refers to

In the method of forming a colored portion on a recording medium according to the present invention, if the liquid composition and the aqueous ink used in the present invention come into contact with each other in a liquid state on the recording medium, they are used. It may be provided by any method. Therefore, it does not matter which of the liquid composition and the ink is applied on the recording medium first. For example, the step (i) may be performed after the step (ii), or the step (ii) may be performed after the step (i). It is also preferable to perform the step (ii) after performing the step (i) and then perform the step (i) again. Further, when the liquid composition is first applied to the recording medium, the time from application of the liquid composition to the recording medium to application of the ink on the recording medium is particularly limited. However, it is preferable that the ink and the liquid composition be applied to the recording medium almost simultaneously or within a few seconds in order to contact each other in a liquid-liquid state.

(Recording Medium) The recording medium used in the above-described method of forming a colored portion on a recording medium of the present invention is not particularly limited, and conventionally used copy paper. So-called plain paper such as bond paper is preferably used. Of course, a coated paper specially prepared for ink jet recording or a transparent film for OHP is also preferably used. Furthermore, it can be suitably used for general high-quality paper and glossy paper.

(Method of Applying Liquid Composition) As a method of applying the liquid composition onto the recording medium, for example, a method of applying the liquid composition to the entire surface of the recording medium by a spray, a roller, or the like can be considered, but more preferably. An ink-jet recording method capable of selectively and uniformly applying the liquid composition only to the colored portion forming region formed by applying the ink, or only to the colored portion forming region and its vicinity. Is preferred. In this case, various ink jet recording methods can be used,
Particularly preferred is ink jet recording of a system in which droplets are ejected by generating bubbles by thermal energy.

<Inkjet Recording Apparatus> Next, the inkjet recording apparatus of the present invention will be described. An ink jet recording apparatus according to the present invention includes an ink container containing an anionic or cationic aqueous ink containing a colorant, a first recording unit including an ink jet recording head for discharging the ink, Is a second recording apparatus including a liquid composition storage section that stores a liquid composition containing fine particles whose surfaces are charged in the opposite polarity in a dispersed state, and an inkjet recording head that discharges the liquid composition. And a unit.
Further, as another type of ink jet recording apparatus, an ink containing section containing an anionic or cationic aqueous ink containing a coloring material, and fine particles whose surface is charged to a polarity opposite to that of the aqueous ink are dispersed. The liquid composition containing section containing the liquid composition contained in the state, the aqueous ink contained in the ink containing section, and the liquid composition contained in the liquid composition containing section are independently formed. An ink jet recording head for discharging. Hereinafter, these will be described.

The ink jet recording apparatus of the present invention is particularly preferably of the type in which a recording signal is applied to the recording ink of the recording head and droplets are ejected by the generated thermal energy. FIG. 1 shows a configuration of a recording head which is a main part of the apparatus.
This is shown in FIGS. FIG. 1 is a cross-sectional view of the head 13 along the ink flow path, and FIG. 2 is a cross-sectional view taken along line AB in FIG.

The recording head 13 is made of a glass, ceramic, or plastic plate having a groove 14 through which ink passes.
Heating head 1 having a heating resistor used for thermal recording
5 (a thin film head is shown in the figure, but is not limited to this). The heating head 15 includes a protective film 16 made of silicon oxide or the like, aluminum electrodes 17-1 and 17-2, a heating resistor layer 18 made of nichrome or the like, a heat storage layer 19, and a substrate having good heat dissipation such as alumina. It consists of 20.

The recording ink 21 reaches the discharge orifice 22 and forms a meniscus 23 by the pressure P. Here, when an electric signal is applied to the aluminum electrodes 17-1 and 17-2, the area indicated by n of the heating head 15 generates heat rapidly, and bubbles are generated in the ink 21 in contact with the area, and the pressure is increased by the pressure. The meniscus 23 projects and becomes an ink droplet 24 from the ejection orifice 22.
Fly towards. FIG. 3 is a schematic diagram of a recording head in which a number of nozzles shown in FIG. 1 are arranged. The recording head is formed by closely contacting a glass plate 27 having a large number of channels and a heating head 28 similar to that described with reference to FIG.

FIG. 4 shows an example of an ink jet recording apparatus incorporating the head described above. In FIG. 4, reference numeral 61 denotes a blade serving as a wiping member, one end of which is held by a blade holding member and serves as a fixed end, forming a cantilever lever. The blade 61 is disposed at a position adjacent to a recording area of the recording head 65,
Further, in the case of the present example, the recording head 65 is held in a form protruding into the moving path of the recording head 65. Reference numeral 62 denotes a cap on the ejection port surface of the recording head 65, which is disposed at a home position adjacent to the blade 61, moves in a direction perpendicular to the moving direction of the recording head 65, and comes into contact with the ink ejection port surface. A structure for performing capping is provided. Reference numeral 63 denotes an ink absorber provided adjacent to the blade 61, which is held in a form protruding into the movement path of the recording head 65, similarly to the blade 61. The blade 61, the cap 62, and the ink absorber 63 constitute an ejection recovery unit 64, and the blade 61 and the ink absorber 63 remove moisture, dust, and the like from the ink ejection port surface.

Reference numeral 65 denotes a recording head which has a discharge energy generating means and discharges ink on a recording material facing a discharge port surface provided with discharge ports to perform recording. Is a carriage for performing the following. The carriage 66 is slidably engaged with a guide shaft 67, and a part of the carriage 66 is connected to a belt 69 driven by a motor 68 (not shown). As a result, the carriage 66 can move along the guide shaft 67, and the recording head 65 can move the recording area and the adjacent area.

Reference numeral 51 denotes a paper feed unit for inserting a recording material,
Reference numeral 52 denotes a feed roller driven by a motor (not shown). With these configurations, the recording material is fed to a position facing the discharge port surface of the recording head 65, and is discharged to a discharge unit provided with a discharge roller 53 as recording proceeds.

In the above configuration, when the recording head 65 returns to the home position at the end of recording or the like, the cap 62 of the ejection recovery section 64 is retracted from the moving path of the recording head 65, but the blade 61 protrudes into the moving path. I have. As a result, the ejection port surface of the recording head 65 is wiped.
When capping is performed by contacting the cap 62 with the ejection port surface of the recording head 65, the cap 62 moves so as to protrude into the movement path of the recording head.

When the recording head 65 moves from the home position to the recording start position, the cap 62 and the blade 61 are at the same position as the position at the time of wiping. As a result, the ejection port surface of the recording head 65 is also wiped during this movement. The movement of the print head 65 to the home position is performed not only at the end of printing or at the time of ejection recovery, but also at the home position adjacent to the printing area at a predetermined interval while the printing head 65 moves through the printing area for printing. And the wiping is performed along with this movement.

FIG. 5 is a diagram showing an example of an ink cartridge 45 containing ink supplied to the head via an ink supply member, for example, a tube. Here, reference numeral 40 denotes an ink storage portion that stores the supply ink, for example, an ink bag, and a rubber stopper 42 is provided at the tip thereof. By inserting a needle (not shown) into the stopper 42, the ink in the ink bag 40 can be supplied to the head. An ink absorber 44 receives the waste ink.
It is preferable that the ink container has a surface in contact with the ink made of polyolefin, particularly polyethylene. Further, as another aspect of the cartridge according to the present invention, the cartridge has two storage portions in which the ink and the liquid composition constituting the ink set according to the present invention are individually stored,
Examples of the cartridge include a cartridge configured to be detachable from a head for discharging the ink and the liquid composition, and configured to be able to supply the recording head with the ink and the liquid composition.

FIG. 11 shows such a cartridge 100.
In the drawing, reference numeral 1003 denotes an ink storage unit that stores ink, and 1005 denotes a liquid composition storage unit that stores a liquid composition. As shown in FIG. 12, the cartridge is configured to be detachable from a recording head 1101 for ejecting each of the ink and the liquid composition, and when the cartridge 1001 is mounted on the recording head 1101, the liquid composition and Ink is configured to be supplied to the recording head 1101.

The ink jet recording apparatus used in the present invention is not limited to the one in which the head and the ink cartridge are separated as described above, and the one in which they are integrated as shown in FIG. Can be

In FIG. 6, reference numeral 70 denotes a recording unit, which is an ink storage unit which stores ink therein, for example,
An ink absorber is housed therein, and the ink in the ink absorber is ejected as ink droplets from a head unit 71 having a plurality of orifices. As a material of the ink absorber, for example, polyurethane can be used. Reference numeral 72 denotes an atmosphere communication port for communicating the inside of the recording unit with the atmosphere. This recording unit 70
Is used in place of the recording head shown in FIG. 4, and is detachable from the carriage 66.

Further, as another embodiment of the recording unit used in the present invention, the ink and the liquid composition are stored in respective storage sections in one ink tank, and the ink and the liquid composition are stored. A recording unit integrally provided with a recording head for ejecting each of them, specifically, for example, FIG.
As shown in FIG. 3, the liquid composition is stored in the storage portion 1201L, the black ink is stored in the storage portion 1201Bk, and the yellow, cyan, and magenta color inks are stored in the color ink storage portions 1201Y, 1201M, and 1201C, respectively. And a recording unit 1201 having a recording head 1203 having separate ink flow paths so that each ink can be ejected individually.

In the recording apparatus used in the present invention,
In the above description, an ink jet recording apparatus that ejects ink droplets by applying thermal energy to ink and a liquid composition has been described as an example. However, a piezoelectric ink jet recording apparatus using a piezoelectric element can be similarly used.

When the method of forming a colored portion on a recording medium according to the present invention is carried out, for example, a recording apparatus in which five recording heads shown in FIG. 3 are arranged on a carriage is used. FIG. 7 shows an example. Reference numerals 81, 82, 83, and 84 denote recording heads for ejecting recording inks of yellow, magenta, cyan, and black, respectively.
Reference numeral 85 denotes a head for discharging the liquid composition used in the present invention. The head is disposed in the above-described printing apparatus, and discharges printing ink of each color according to a printing signal. The liquid composition used in the present invention is applied, for example, at least to a portion where the recording ink of each color adheres to the recording paper before discharging the recording ink of each color. FIG. 7 shows an example in which five recording heads are used. However, the present invention is not limited to this, and as shown in FIG.
It is also preferable to carry out the treatment separately for each of 1M, cyan 801C, black 801Bk and colorless liquid composition 801S. Of course, the heads may be arranged such that the recording order of the liquid composition and the ink is opposite to the above-described order.

FIG. 16 is a schematic perspective view showing a schematic configuration of another embodiment of the ink jet printing apparatus according to the present invention. 16, reference numeral 1604 denotes a scanning rail extending in the main scanning direction of the carriage 1603 and slidably supporting the carriage.
This is a drive belt for transmitting a driving force for reciprocating the drive lever 03. Also, 1606 and 1607, and 1608 and 1
Reference numeral 609 denotes a pair of transport rollers disposed before and after the print position of the print head, and for nipping and transporting the printing material 1610. A printing material 1610 such as paper is guided and supported by a platen (not shown) for regulating a printing surface flat at a printing position in a press-contact state. At this time, each of the head cartridges (heads) 1601, 16 mounted on the carriage 1603
The ejection port forming surface of No. 02 protrudes downward from the carriage 1603 and the recording medium transport rollers 1607 and 1609.
The recording medium 1610 is positioned between the recording medium 1610 and pressed in parallel with a guide surface of a platen (not shown).

In FIG. 16, a total of six head cartridges are positioned and mounted on a carriage 1603. In this embodiment, the yellow print head 160 is moved from the left end to the right side on the carriage 1603 in the drawing.
1Y, magenta print head 1601M, cyan print head 1601C, black print head 1
601B, a liquid composition ejection head 1602, and a second black print head 1601BB. The liquid composition discharge head 1602 discharges a liquid composition having a reactivity with the coloring material in the ink to the recording medium 1610. The second black print head 1601BB at the right end is a print head that uses black ink used in sub-scanning printing in reciprocating printing. That is, the black print head 160
1B, a liquid composition ejection head 1602 is arranged (on the right side), and the black print head 1601BB is arranged on the next (right end),
As a result, first, a droplet of the aqueous ink is applied to the recording medium in the first step, and then, the aqueous ink and the liquid applied to the recording medium in the first step are applied in the second step. -Applying a droplet of the liquid composition so as to be in contact with the liquid state, and further mixing the aqueous composition and the liquid composition formed on the recording medium by the first and second steps in the third step. It is possible to further apply droplets of the aqueous ink so as to come into contact with the liquid in a liquid-liquid state.

In FIG. 16, a recovery unit 1611 is provided on the left side of the print area. In the recovery unit 1611, the head cartridge 160
1, 1602, print heads 1601Y, 1601M, 1601C, 1601 from left to right.
Cap 1612 for capping B respectively
Are sequentially arranged, and then (on the right side) a cap 1613 for capping the liquid composition ejection head 1602
, And a cap 1612 for capping the second black print head 1601BB is disposed on the right (right end) thereof. Each cap is provided so as to be able to move up and down in the vertical direction. When the carriage 1603 is at the home position, the corresponding caps 1612 and 1613 are pressed against the discharge port forming surfaces of the heads 1601 and 1602, respectively. As a result, the ejection openings of the heads 1601 and 1602 are sealed (capped), thereby preventing the ink from thickening and sticking due to evaporation of the ink solvent in the ejection openings, thereby preventing occurrence of ejection failure.

The recovery unit 1611 is provided with a suction pump 1614 communicating with each of the caps 1612 and 1613 and a suction pump 1615 communicating with the cap 1613. These pumps 1614 and 1615 are used to perform a suction recovery process by capping their discharge port forming surfaces with caps 1612 and 1613 when a discharge failure occurs in the print head 1601 or the liquid composition discharge head 1602. used. Further, a blade 1617 for the liquid composition ejection head 1602 is disposed between the fifth liquid composition cap 1613 from the left end and the sixth (right end) black ink cap 1612, and the right end cap Right side of 1612 (print area side)
, A blade 1616 for each print head 1601 is arranged. The blade 1617 is held by a blade holder 1619, and the blade 1616 is held by a blade holder 1618. In this embodiment, the blade holders 1618 and 161
9 is moved up and down by a blade elevating mechanism (not shown) each driven by the movement of the carriage 1603, so that the blades 1616 and 1617 move the head 16
Positions (wiping position) protruding for wiping ink and foreign matter adhered to the ejection port forming surfaces of Nos. 01 and 1602
And a retracted position (standby position) not in contact with the discharge port forming surface. In this case, the print head 16
16 wiping the liquid composition ejection head 1602 and the blade 1617 wiping the liquid composition ejection head 1602
Is configured to be able to ascend and descend independently of each other.

FIG. 17 is a schematic diagram showing the wiping operation of the ink jet printing apparatus of FIG. In FIG. 16, as shown in FIG. 16A, after the print head blade 1616 protrudes (rises), the carriage 160
Each head mounted on 3 moves from the right side (print area side) toward the home position. The raised print head blade 1616 sequentially wipes the print head 1601 as the carriage 1603 moves leftward as shown in FIG. And
As shown in (C), when the liquid composition ejection head 1602 comes before (to the right of) the print head blade 1616, the blade 1616 retreats (down) to the standby position, and the blade 1616 and the liquid composition Object ejection head 1
Contact with 602 is prevented.

Further, when the carriage 1603 moves to the left and the liquid composition discharge head 1602 has passed the print head blade 1616, as shown in (D), the print head blade 1616 and the liquid composition discharge head Both of the blades 1617 protrude (raise). As the carriage 1603 moves to the left, the blade 1617 wipes the liquid composition ejection head 1602 with the blade 1617 and moves the blade 1616 as shown in FIG.
16, the wiping of the rightmost print head 1601BB is performed at the same time. After the wiping of all the heads 1601 and 1602 is completed, both blades 1616 and 1617 are retracted (downward) as shown in FIG.

In the embodiment shown in FIGS. 16 and 17, when the carriage 1603 moves from the print area side (right side) to the home position side where the recovery unit 1611 is located,
Although the wiping is performed by the blades 1616 and 1617, the wiping direction is not limited to this, and the wiping may be performed when moving from the home position side to the right side (print area side).

The ink jet printing apparatus shown in FIG.
The liquid composition discharging head 1602 discharges the liquid composition according to the present invention, which has reactivity with the coloring material in the ink, onto the printing material 1610, and print heads 1601.
The recording medium 1610 is configured so that a recorded matter can be formed by contacting the ink ejected from the recording medium 1610 on the recording medium 1610. On the recording medium 1610, the coloring material in the ink reacts with the liquid composition, so that the coloring material in the ink is adsorbed on the surface of the fine particles in a monomolecular state, and the fine particles form an image. And an image having excellent color uniformity can be obtained.

[0151]

Next, the present invention will be described more specifically with reference to examples and comparative examples. In the following description, parts and% are based on weight unless otherwise specified. The zeta potential in the text is determined by dispersing the liquid composition with ion-exchanged water so that the solid content of the fine particles becomes 0.1%, and then measuring the zeta potential with a BI-ZETA plu (Brookhaven).
s, liquid temperature 20 ° C., using an acrylic cell). pH, the prepared liquid composition as a measurement sample,
pH meter (manufactured by Horiba, Ltd., Castany pH)
The measurement was performed under the condition of a liquid temperature of 25 ° C. using a meter D-14). The average particle diameter of the fine particles contained in the liquid composition is determined by dispersing the liquid composition with ion-exchanged water so that the solid content concentration of the fine particles becomes 0.1%, and then using a dynamic light scattering particle size distribution analyzer ( Brookhaven BI-90, liquid temperature 20
C., using an acrylic cell).

First, a method for preparing the liquid composition used in the present invention will be described. After mixing and dissolving each of the components shown below, the mixture is pressure-filtered with a membrane filter having a pore size of 1 μm (trade name, Fluoropore Filter, manufactured by Sumitomo Electric Industries, Ltd.), and the liquid compositions A and B used in the present invention. , C and D. <Composition of liquid composition A>-Glycerin 7.5% by weight-Diethylene glycol 7.5% by weight-Alumina hydrate (average particle diameter: 0.17 µm) 1
0.0% by weight, acetic acid 3.0% by weight, water 72.0% by weight

Here, the alumina hydrate used above is:
It was obtained by the following synthesis method. (Synthesis example of alumina hydrate) US Pat. No. 4,24
Aluminum dodexide was produced by the method described in US Pat. No. 2,271. Next, U.S. Pat. No. 4,202,870
The aluminum dodecoxide was hydrolyzed to produce an alumina slurry by the method described in the above item. Water was added to the alumina slurry until the solid content of the alumina hydrate became 7.9% by weight. The pH of the alumina slurry is 9.3.
Met. Adjust the pH by adding 3.9% nitric acid solution,
A colloidal sol was obtained. This colloidal sol was spray-dried at 83 ° C. to produce an alumina hydrate. The surface of the alumina hydrate is positively charged in water, and shows a cationic property.

The pH of the liquid composition A obtained above was 3.
5, and the zeta potential was +39 mV. Further, the ink tank was filled with the liquid composition A, and a storage test at 60 ° C./Dry was performed for 1 month. Thereafter, the inside of the ink tank was visually observed, but no sediment was found in the ink tank. When recording was performed using the stored ink, the ejection stability from the recording head was also good.

<Composition of Liquid Composition B> Glycerin 7.5% by weight Diethylene glycol 7.5% by weight Colloidal silica (average particle diameter: 0.02 μm, trade name: Snowtex AK, Nissan Chemical Industries, Ltd.) 10).
0% by weight, acetic acid 3.0% by weight, water 72.0% by weight Here, the above-mentioned colloidal silica has been subjected to a cationic treatment on its surface, and exhibits cationicity in water.

The pH of the liquid composition B obtained above was 3.
7, and the zeta potential was +68 mV. The ink tank was filled with the liquid composition B, and a storage test at 60 ° C./Dry was performed for 1 month. Thereafter, the inside of the ink tank was visually observed, but no sediment was found in the ink tank. When recording was performed using the stored ink, the ejection stability from the recording head was also good.

<Composition of Liquid Composition C> Glycerin 7.5% by weight Diethylene glycol 7.5% by weight Alumina hydrate (average particle diameter: 0.17 μm) 1
0.0% by weight ・ 2.5% by weight of formic acid ・ 72.5% by weight of water As the alumina hydrate used above, the same as the liquid composition A was used.

The pH of the liquid composition C obtained above was 3.
4, and the zeta potential was +39 mV. Further, the ink tank was filled with the liquid composition C, and a storage test at 60 ° C./Dry for 1 month was performed. After that, the inside of the ink tank was visually observed, but no sediment was found in the ink tank. When recording was performed using the stored ink, the ejection stability from the recording head was also good.

<Composition of Liquid Composition D> Glycerin 7.5% by weight Diethylene glycol 7.5% by weight Colloidal silica (average particle diameter: 0.02 μm, trade name: Snowtex AK, Nissan Chemical Industries, Ltd.) 10).
0% by weight ・ Formic acid 2.5% by weight ・ Water 72.5% by weight Here, the above-mentioned colloidal silica has been subjected to a cationic treatment on the surface similarly to the case of the liquid composition B, and has a cationic property in water. The ones shown were used.

The pH of the liquid composition D obtained above was 3.
5, and the zeta potential was +68 mV. Also, the ink tank was filled with the liquid composition D, and a storage test at 60 ° C./Dry was performed for 1 month. Thereafter, the inside of the ink tank was visually observed, but no sediment was found in the ink tank. When recording was performed using the stored ink, the ejection stability from the recording head was also good.

Next, the production of the ink subsets 1 and 2 used in Examples and Comparative Examples of the present invention will be described. <Preparation of Ink Subset 1> The components shown below were mixed, sufficiently stirred and dissolved, and then pressure-filtered with a fluoropore filter (trade name, manufactured by Sumitomo Electric Industries, Ltd.) having a pore size of 0.45 μm. Black and cyan dye inks, B
k1 and C1 were obtained, and the combination of these dye inks was designated as ink subset 1.

[Black Ink Bk1] C.I. I. Direct Black 195 2.5 parts ・ 2-Pyrrolidone 10 parts ・ Glycerin 5 parts ・ Isopropyl alcohol 4 parts ・ Sodium hydroxide 0.4 part ・ Water 78.1 parts

The pH of the black ink Bk1 was 9.8.
Met. The black ink Bk1 is a pH-dependent dye, and the aggregation start pH of the dye is 7.5 (that is, the pH of the solution).
Is less than 7.5, the dye begins to aggregate). The pH of the liquid mixture obtained by mixing the liquid compositions A, B, C and D with the black ink Bk1 at a weight ratio of 1: 1 was 4.3, 4.6, 4.3 and 4 respectively. Was 5.5.

[Cyan Ink C1] 3 parts of CuPc (COOH) ₄ 7 parts of ethylene glycol 10 parts of diethylene glycol 0.3 parts of acetylenol EH (manufactured by Kawaken Chemicals) 0.3 parts of water 79.7 parts of water

The pH of the cyan ink C1 obtained above was 10.2. Cyan C1 is a pH-dependent dye, and the aggregation initiation pH of the dye is 8.0 (that is, the pH of the solution).
Is less than 8.0, the dye begins to aggregate). The pH of a liquid mixture obtained by mixing the liquid compositions A, B, C and D with the cyan ink C1 at a weight ratio of 1: 1.
Was 4.9, 5.1, 4.7 and 4.9, respectively.

The liquid compositions A to A obtained as described above
D and the ink subset 1 were used to construct the ink set of the present invention, and recording was performed on PPC paper (manufactured by Canon). FIG. 4 shows the used inkjet recording apparatus.
A color image was formed using the same recording apparatus as shown in FIG. 8 and the five recording heads shown in FIG. On this occasion,
First, the liquid composition was first deposited on the recording paper, and then the ink was deposited. Specifically, three-pass fine printing for printing the printing area by three scans was performed. At this time, the liquid composition was printed at each pixel position where one of the cyan and black inks was printed for each pass. That is, the logical sum of the print data of cyan and black for each pass was used as print data of the liquid composition. The type of the fine mask at the time of fine printing is not particularly limited, and a known technique can be used.

The recording head used here was 600 dpi.
And a driving frequency of 9.
6 kHz. When a 600 dpi head was used, the ejection amount per dot was 15 ng for the cyan ink and the liquid composition, and 30 ng per dot for the black ink. These recording conditions are the same throughout the examples and comparative examples where the dye ink described below is used.

[Examples 1 to 4] The liquid compositions A, B, C, and D obtained above and ink subset 1 (Bk
Printing was performed using each color ink of 1 and C1). Table 1 shows the recording conditions.

[0169]

[Comparative Examples 1 and 2] <Preparation of Ink Subset 2> The following components were mixed, sufficiently stirred and dissolved, and then a fluoropore filter having a pore size of 0.45 μm (trade name, Sumitomo Electric Industries, Ltd.) )), And filtered under pressure to obtain black and cyan dye inks, B
k2 and C2 are obtained, and this recording liquid is designated as ink subset 2.

[Black ink Bk2]-Food black 2 2.5 parts-2-Pyrrolidone 10 parts-Glycerin 5 parts-Isopropyl alcohol 4 parts-Sodium hydroxide 0.3 part-Water 78.2 parts

The pH of the thus-obtained black ink Bk2 was 9.5. PH of a mixture obtained by mixing the liquid composition A and the black ink Bk2 at a weight ratio of 1: 1
Was 4.2. In the case of the black ink Bk2, there is no aggregation start pH of the dye.

[Cyan Ink C2] C.I. I. Acid Blue 7 3 parts ・ Ethylene glycol 7 parts ・ Diethylene glycol 10 parts ・ Acetyleneol EH (manufactured by Kawaken Chemicals) 0.2 part ・ Water 79.8 parts

The pH of the cyan ink C2 obtained above was 10.0. Liquid composition A and cyan ink C
The pH of the mixture obtained by mixing 1 and 1 at a weight ratio of 1: 1 is 4.
It was 8. In the case of the cyan ink C2, there is no aggregation start pH of the dye.

Printing was performed using ink subsets 1 and 2 and liquid composition A. Table 2 shows the recording conditions. The recording head used in the recording using only the ink subset 1 and the ink subset 2 (Comparative Examples 1 and 2)
It had a recording density of 600 dpi, and the driving conditions were a driving frequency of 9.6 kHz. When a 600 dpi head is used, the ejection amount per dot is about 15 ng for cyan ink and about 30 ng per dot for black ink under the same conditions as in Examples 1 to 4. Recordings were made.

[0176]

[Evaluation] Examples 1 to 4 and Comparative Example 1
Each of the recorded images obtained in and 2 was evaluated according to the following evaluation methods and evaluation criteria. Table 3 shows the results.

<Evaluation Method and Evaluation Criteria of Recorded Image> (1) Color Development A halftone patch pattern of cyan ink was printed using a printer. Specifically, 10 patches of a halftone patch pattern with a printing ratio increased by 10% were printed up to solid patches, and each patch was measured. The evaluation of the color development was performed by calculating the saturation value of each patch. For details,
On the basis of the saturation value of Comparative Example 2, the ratios of the saturation values of the corresponding patches of the respective Examples and Comparative Examples were calculated and averaged. At this time, the image processing of the printed image was performed under the same conditions, and the colorimetry was performed 24 hours after printing, using a light source: D5
0, visual field: measured at 2 °. Colorimetric value is L of CIE
^The values were output as ^* a ^* b ^* values, and the saturation value was defined as the square root of the sum of the square values of the a ^* and b ^* values. In addition, coated paper for inkjet (trade name: Color BJ Paper LC-101, Canon Inc.)
Was printed with Ink Subset 1 and the average chroma ratio with the printed matter of Comparative Example 2 was 1.2 times.

The evaluation criteria are as follows. A: Average saturation ratio is more than 1.15 times B: Average saturation ratio is more than 1.00 to 1.15 times or less C: Average saturation ratio is 1.00 times or less

(2) Bleeding After using a printer to print solid cyan and black images adjacent to each other, the bleeding at the boundary between colors was visually evaluated. The evaluation criteria are as follows. A: Bleeding cannot be visually recognized. B: Bleeding is hardly noticeable. C: Bleeding is at a level where there is practically no problem. D: Bleeding so that the color boundary paper is not clear.

(3) Uniformity After printing a solid image of cyan and black inks using the above-described printer, the uniformity of color with respect to white haze and color unevenness was visually evaluated. In particular, colors having poor uniformity were evaluated. The evaluation criteria are as follows. A: Almost no white haze or color unevenness occurs. B: White haze and color unevenness are slightly visible along the paper fibers,
It is a level with virtually no problem. C: White haze and color unevenness are remarkably observed along the fiber of the paper.

(4) Scratch Resistance Solid images of cyan and black inks were printed using the printer described above. Sixteen hours after the printing, a silk-bon paper was overlaid on the printing part, and 3.5 cm × 3.
Place the weight of 5cm, while applying a pressure of 40g / cm ³ 15cm / sec. The abrasion resistance of the printed portion was evaluated by pulling the silk paper at the speed shown in FIG. In particular, colors having poor abrasion resistance were evaluated. The evaluation criteria are as follows. A: Ink drop hardly occurs. B: Ink slightly adheres to the silbon paper, but the color fading of the printed portion is not noticeable. C: A large amount of ink adheres to the silk paper, and the color of the printed portion is clearly discolored.

(5) Texture After printing solid images of cyan and black inks using the above-described printer, the texture of the recording medium was visually evaluated. The evaluation criteria are as follows. A: Both the printed portion and the non-printed portion have no uncomfortable feeling and leave the texture of plain paper. B: The texture differs between the printed portion and the unprinted portion, or the texture of the entire recording medium is significantly different from the texture of plain paper.

[0184]

[0185]

As described above, according to the present invention,
Bleeding is suppressed at the color boundary, has a wide color reproduction range similar to that of coated paper, and has little white color unevenness even in image areas where the amount of applied ink is large, such as shadows and solids, and improves color uniformity. An ink set combining a liquid composition and an aqueous ink capable of providing an excellent recorded image, a method of forming a colored portion on a recording medium, and an ink jet recording apparatus are provided. According to the present invention, particularly, when color inkjet recording is performed on plain paper, excellent color developability and color uniformity comparable to inkjet coated paper can be obtained while leaving the texture of plain paper, and An ink jet recorded image having less solid streaks in the solid image portion and excellent scratch resistance in the printed portion can be obtained. Further, according to the present invention, there is provided an ink set which is excellent in storage stability and ejection stability from a recording head and excellent in ink jet recording characteristics.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a head section of an ink jet recording apparatus.

FIG. 2 is a cross-sectional view of a head section of the inkjet recording apparatus.

FIG. 3 is an external perspective view of a head unit of the inkjet recording apparatus.

FIG. 4 is a perspective view illustrating an example of an ink jet recording apparatus.

FIG. 5 is a vertical sectional view of the ink cartridge.

FIG. 6 is a perspective view of a recording unit.

FIG. 7 is a perspective view showing a recording unit in which a plurality of recording heads used in an embodiment of the present invention are arranged.

FIG. 8 is a perspective view of another recording head used in the present invention.

FIG. 9 is a schematic cross-sectional view illustrating a state of a colored portion when inkjet recording is performed on coated paper.

FIG. 10 is an explanatory diagram illustrating the relationship between the solubility of the ink dye and the solution pH.

FIG. 11 is a schematic view showing an embodiment of the ink cartridge according to the present invention.

FIG. 12 is a schematic view of a recording head equipped with the ink cartridge of FIG. 11;

FIG. 13 is a schematic view showing one embodiment of a recording unit according to the present invention.

FIG. 14 is a schematic cross-sectional view illustrating a state of a colored portion of an inkjet image according to the present invention.

FIG. 15 is a schematic view showing a process of forming a colored portion of an ink jet recorded image according to the present invention.

FIG. 16 is a partially broken perspective view schematically showing one embodiment of an ink jet printing apparatus according to the present invention.

17A and 17B are schematic diagrams showing a wiping operation of the ink jet printing apparatus of FIG. 16, wherein FIG. 17A is an elevation of an ink blade, FIG.
(C) lowers the ink blade, (D) raises both blades after the liquid composition has reached the proper position, (E) wipes the liquid composition and the second black ink head, (F) Indicates the lowering of both blades, respectively.

[Explanation of symbols]

 13: Head 14: Groove 15: Heating Head 16: Protective Film 17-1: Aluminum Electrode 17-2: Aluminum Electrode 18: Heating Resistor Layer 19: Heat Storage Layer 20: Substrate 21: Ink 22: Discharge Orifice 23: Mesnicus 24 : Ink droplet 25: recording material 26: multi-groove 27: glass plate 28: heating head 40: ink bag 42: stopper 44: ink absorber 45: ink cartridge 51: paper feed section 52: paper feed roller 53: discharge Paper roller 61: Blade 62: Cap 63: Ink absorber 64: Head recovery unit 65: Recording head 66: Carriage 67: Guide shaft 68: Motor 69: Belt 70: Recording unit 71: Head unit 72: Atmospheric communication hole 81- 84: Recording head 85: Liquid composition discharge head

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masao Kato 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Yutaka Kurabayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Kya Inside Non-corporation (72) Inventor Yuji Kondo 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hiroshi Tomioka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Makiko Endo 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc.

Claims (37)

[Claims] 1. An ink set independently comprising an anionic or cationic aqueous ink containing a coloring material and a liquid composition containing fine particles having a surface charged to the opposite polarity to the ink in a dispersed state. Wherein the ink and the liquid composition are adjusted so that the pH of the mixed liquid when they are mixed at a weight ratio of about 1 to 1 is at least a pH that causes aggregation of the coloring material. An ink set, characterized in that: 2. The ink set according to claim 1, wherein the fine particles in the liquid composition, when mixed with the aqueous ink, adsorb the coloring material on the surface of the fine particles while preventing aggregation of the coloring material. 3. The ink set according to claim 1, wherein when the fine particles in the liquid composition are mixed with the aqueous ink, the coloring material in the ink is adsorbed on the surface of the fine particles in a monomolecular state. 4. The liquid composition has a zeta potential of +5 to +9.
The ink set according to claim 1, wherein the ink set is 0 mV. 5. The liquid composition comprises an acid and has a pH of 2 to 5.
The ink set according to claim 1, wherein the ink set is adjusted to 7. 6. The ink set according to claim 5, wherein the primary dissociation constant pKa of the acid in water is 5 or less. 7. The liquid composition having a zeta potential of -5 to -9.
The ink set according to claim 1, wherein the ink set is 0 mV. 8. The liquid composition comprises a base and has a pH of 7
The ink set according to any one of claims 1 to 3, wherein the ink set is adjusted to a value of from 12 to 12. 9. A base having a first-order dissociation constant pKb of 5 in water.
The ink set according to claim 8, wherein: 10. The ink set according to claim 1, wherein the fine particles of the liquid composition have an average particle diameter in a range of 0.005 to 1 μm. 11. The ink set according to claim 1, wherein the coloring material is a dye. 12. The ink according to claim 1, wherein the ink is at least one selected from a yellow ink, a magenta ink, a cyan ink, a black ink, a red ink, a blue ink, and a green ink. set. 13. The ink set according to claim 1, wherein the ink contains an anionic compound. 14. The ink set according to claim 13, wherein the anionic compound contains at least one carboxylic acid group. 15. The ink set according to claim 1, wherein the ink contains a water-soluble dye having an anionic group. 16. The ink set according to claim 1, wherein the ink contains a pigment having an anionic group on its surface as an anionic compound. 17. The ink set according to claim 1, wherein the ink contains a pigment and an anionic compound that is a dispersant for the pigment. 18. A water-soluble dye having an anionic group,
16. The ink set according to claim 15, comprising at least one carboxylic acid group. 19. The ink set according to claim 1, further comprising a pigment having an anionic group on the surface as the anionic compound. 20. The ink set according to claim 1, wherein the aqueous ink contains a pigment and an anionic compound which is a dispersant for the pigment. 21. The ink set according to claim 1, wherein the ink contains a cationic compound. 22. The ink set according to claim 1, wherein the cationic compound is a water-soluble dye having a cationic group. 23. The ink set according to claim 1, further comprising a pigment having a cationic group on the surface as the cationic compound. 24. The aqueous ink according to claim 1, further comprising a pigment and a cationic compound which is a dispersant for the pigment.
0. The ink set according to any one of 0. 25. Drops of an anionic or cationic aqueous ink containing a coloring material and droplets of a liquid composition containing, in a dispersed state, fine particles whose surface is charged to a polarity opposite to that of the ink. Is a method of forming a colored portion on a recording medium, the method including a step of ejecting both droplets toward the recording medium so that a liquid-liquid contact state is formed on the recording medium. In addition, each of the aqueous ink and the liquid composition is adjusted so that the pH of a mixed liquid obtained by mixing the respective aqueous inks at a weight ratio of about 1 to 1 is at least a pH that causes aggregation of the coloring material. A method for forming a colored portion on a recording medium, characterized in that: 26. After the step of applying the liquid composition droplets to a recording medium, the aqueous ink droplets are formed as follows:
26. The forming method according to claim 25, further comprising a step of applying the liquid composition on the recording medium so as to be in contact with the liquid composition in a liquid-liquid state. 27. The method according to claim 27, wherein the step of applying the droplets of the aqueous ink to a recording medium includes the steps of:
26. The forming method according to claim 25, further comprising a step of applying the aqueous ink on the recording medium so as to come into contact with the aqueous ink in a liquid-liquid state. 28. The method according to claim 28, wherein the step is a first step of applying the aqueous ink droplets to the recording medium, and the aqueous ink and the liquid-liquid state applied on the recording medium in the first step. A second step of applying droplets of the liquid composition so as to be in contact with each other, and a liquid-liquid mixture of the aqueous ink and the liquid composition formed on the recording medium by the first and second steps. 26. The forming method according to claim 25, further comprising: a third step of further applying a droplet of the aqueous ink so as to come in contact with the state. 29. At least one of the application of a droplet of the liquid composition to a recording medium and the application of an aqueous ink droplet to a recording medium is ejected from an orifice according to a recording signal. The forming method according to any one of claims 25 to 28, wherein the forming method is performed by an ink jet recording method. 30. The forming method according to claim 29, wherein the ink jet recording method is a method of ejecting liquid droplets by applying thermal energy. 31. A storage unit that uses the ink set according to any one of claims 1 to 24, and that stores the aqueous ink and the liquid composition that constitute the ink set independently.
An ink jet recording apparatus comprising: heads for individually discharging the liquid composition and the aqueous ink. 32. The ink jet recording apparatus according to claim 31, wherein the head is an ink jet recording head. 33. An ink set independently comprising an ink containing an anionic or cationic coloring material and a liquid composition containing fine particles reactive with the coloring material in a dispersed state, When the ink and the liquid composition are mixed in a liquid state, the fine particles in the composition are in a molecular state in which the color material has a color material in the ink on the surface of the fine particles in the ink. So that the pH of the mixture when the ink and the liquid composition are mixed and subjected to a liquid-liquid reaction is adjusted to a pH that causes the aggregation of the coloring material. An ink set characterized by being adjusted. 34. An ink set independently comprising an ink containing an anionic or cationic coloring material and a liquid composition containing fine particles reactive with the coloring material in a dispersed state, When the ink and the liquid composition are mixed in a liquid state, the fine particles in the composition are in a molecular state in which the color material has a color material in the ink on the surface of the fine particles in the ink. Is maintained while maintaining the above conditions, thereby destabilizing the dispersion state of the fine particles to cause aggregation of the fine particles, and mixing the ink and the liquid composition to cause a liquid-liquid reaction. An ink set, wherein the pH of the mixed liquid when adjusted is adjusted to a pH that causes the aggregation of the coloring material. 35. An ink set independently comprising an ink containing an anionic or cationic coloring material and a liquid composition containing fine particles reactive with the coloring material in a dispersed state, The fine particles in the composition, when the ink and the liquid composition are mixed in a liquid state with each other, is to uniformly adsorb a single molecule of the coloring material in the ink on the surface,
And an ink set wherein the pH of the mixed liquid when the ink and the liquid composition are mixed and subjected to a liquid-liquid reaction is adjusted to a pH that causes the aggregation of the coloring material. . 36. Coloring formed by performing a liquid-liquid reaction between an ink containing an anionic or cationic coloring material and a liquid composition containing fine particles reactive with the coloring material in a dispersed state. An image having a colored portion, wherein the colored portion includes the fine particles and the aggregate of the coloring material, in which the coloring material is uniformly adsorbed or bonded to the surface in a single molecule state. 37. An anionic or cationic aqueous ink containing a coloring material and a liquid composition containing fine particles whose surface is charged in the opposite polarity to that of the ink in a dispersed state are independently contained. Wherein the ink and the liquid composition are each mixed so that the pH of a mixture obtained by mixing the inks and the liquid composition at a weight ratio of about 1 to 1 is such that the color material causes aggregation. An ink set, wherein the pH of the ink set is adjusted.