JP2006037087A - Dispersible colorant and method for producing the same, aqueous ink using the same, ink tank, ink jet recording apparatus, ink jet recording method, and ink jet recorded image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dispersible coloring material that uses a coloring material substantially insoluble in water and has sufficiently high dispersion stability, to provide a process for simply producing the dispersible coloring material and to provide an aqueous ink for inkjet recording using the dispersible coloring material that allows the dispersible coloring material to be stably dispersed therein and at the same time can impart excellent image grade (image density), excellent rub-off resistance and marker resistance to the resulting printed matter. <P>SOLUTION: The dispersible coloring material comprises a coloring material and electrically-chargeable resin pseudo-fine particles smaller than the coloring material which are fixedly bonded or fusion-bonded to the coloring material wherein the coloring material itself has a surface charge. The inkjet ink using the dispersible coloring material is provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a dispersible color material and a method for producing the same, and also relates to an aqueous ink jet recording ink, an ink tank, an ink jet recording apparatus, an ink jet recording method, and an ink jet recorded image using the same.

  The ink jet method is a method of recording images, characters, etc. by ejecting micro droplets of ink from nozzles to reach the recording medium (paper, etc.) based on various operating principles. Are easy to use, have high flexibility in recording patterns, and do not require development and fixing operations, and are rapidly spreading in various applications. Furthermore, in recent years, full-color multi-color ink jet recording system technology has been developed, and it is also possible to form multi-color images that are comparable to multi-color printing by conventional plate-making systems and printing by color photographic systems. In the case where the number of copies is small, printed matter can be obtained at a lower cost than ordinary multicolor printing or printing, and therefore it is being widely applied to the field of full-color image recording.

  In response to demands for further improvement in recording characteristics such as higher recording speed, higher definition, and full color, improvements have been made to ink jet recording apparatuses and recording methods. The performance required for the ink for ink jet recording used in the ink jet recording apparatus is as follows: (1) A uniform image with high resolution and high density without blurring or fogging can be obtained on paper; (2) Nozzle tip Clogging due to drying of the ink in the ink does not occur, the ejection responsiveness and ejection stability are always good, (3) the ink fixing property is good on the paper, and (4) the fastness of the image is good. (5) Long-term storage stability is good. In particular, with the recent increase in printing speed, there has been a demand for ink that can quickly dry and fix ink and obtain high-quality printing even when printing on plain paper such as copy paper.

  In response to such demands, as a coloring material for ink jet recording ink, an ink using a pigment that is a water-insoluble coloring material that is excellent in water resistance and weather resistance of an image has been energetically advanced, It has been introduced in the field of large format printers. Further, as a trend in recent years, in order to obtain better ink jet images for office and personal use printers, inks using pigments are being studied. In such applications, the use of plain paper is mainly used as the recording medium, and in consideration of compatibility with special paper such as glossy paper, image fixability, scratch resistance, character quality, and image density. Improvements in several properties such as water resistance are required more than ever.

  In order to use such a water-insoluble colorant, particularly a pigment, as an aqueous inkjet recording ink, it is first necessary to stably disperse the colorant in water. In general, when a water-insoluble colorant is used as an aqueous ink jet recording ink, the dispersion is stabilized using a surfactant or a polymer dispersant (also referred to as a dispersion resin).

  For example, Patent Document 1 discloses an ink for ink jet recording using a color material dispersed and stabilized by a dispersion resin. In this case, since the dispersion resin itself has a high affinity for water, that is, its solubility in water is large, there is a problem in that it is easily detached from the color material surface and cannot maintain sufficient stability in the long term. In particular, when the ink is landed on plain paper, the highly hydrophilic dispersion resin functions as a penetrant and penetrates with the colorant, resulting in a problem that a sufficient image density cannot be obtained. Occurred. In addition, when an ink for ink jet recording containing a water-soluble polymer component such as a dispersion resin is used, ink sticking may occur around or inside the nozzle of the ink jet recording apparatus. For this reason, the size and direction of the ejected ink droplets are not kept constant. As a result, the image is disturbed, and a problem may arise when a high-definition image is obtained. Furthermore, in order to improve the scratch resistance of images on plain paper and glossy paper, when the amount of water-soluble dispersion resin is increased, the viscosity of the ink increases and the ink discharge stability from the ink jet recording apparatus is increased. There was a problem that it was extremely difficult to maintain the sex.

  Patent Document 2 discloses an ink for ink jet recording in which a pigment is dispersed with a polyoxyethylene alkyl ether sulfate ester salt as a surfactant. Here, when a coloring material is dispersed using a surfactant, the surfactant strongly adsorbed to the coloring material may act simultaneously as a penetrating agent. Therefore, the color material penetrates deeply from the surface of the paper when it is landed on the recording paper, resulting in a problem that it is difficult to obtain a high print density. In addition, since the colorant dispersed using the surfactant does not have a component such as a resin having an action of binding on the paper surface, there is a problem that the scratch resistance and marker resistance of the image cannot be sufficiently obtained. There was a thing.

  Further, as a method of stably dispersing the color material without containing a dispersion resin or a surfactant, there is a method of chemically modifying the surface of the water-insoluble color material. For example, Patent Document 3 discloses an aqueous pigment ink using self-dispersing carbon black in which a hydrophilic group is bonded to the surface of carbon black directly or through another atomic group as a coloring material. Such a surface chemical modification pigment is called a self-dispersion pigment and does not require a water-soluble resin or the like, and thus exhibits good ink jet ejection stability. Since they are not included, the adhesion of the color material to the recording paper is weak, and it is necessary to improve the scratch resistance and marker resistance of the formed image.

  In addition to the above dispersion technique, Patent Document 4 discloses a method in which a colorant is dispersed in an organic solvent, followed by phase inversion emulsification, encapsulating the colorant with a self-dispersing resin, and then water dispersion and solvent removal. Has been. This is a so-called microcapsule-type pigment. In this case as well, it is necessary to increase the hydrophilicity of the resin to be coated in order to obtain sufficient dispersion stability. However, dispersibility increases by increasing hydrophilicity, but the coated resin may be detached from the pigment surface, which increases the viscosity of the ink and makes it difficult to balance ejection stability and dispersion stability. However, it has been clarified by the study of the present inventors.

  As a method for encapsulating the colorant with a resin, other methods such as Non-Patent Document 1, Patent Document 5, Patent Document 6, Patent Document 7, and Patent Document 8 are studied. Non-Patent Document 1 and Patent Document 5 describe the encapsulation of pigments by water-based precipitation polymerization or the combination of pigments and resins. Here, both of the colorants have a large particle size and water-based inkjet recording. The dispersion stability was insufficient for use in the production.

  Patent Document 6 and Patent Document 7 both have a dispersed particle size suitable for ink jet recording by dispersing a coloring material in advance with a reactive surfactant. A method is disclosed in which a resin is deposited by polymerizing with other monomers to coat or modify the color material surface. Furthermore, Patent Document 8 discloses a technique in which a coloring material is dispersed with a surfactant that satisfies special conditions, followed by aqueous precipitation polymerization. In these methods, the color material obtained by modifying the obtained resin is essentially dispersion-stabilized by the presence of a surfactant or a water-soluble polymer dispersant in the ink, as described above. There is a problem that it is extremely difficult to achieve both the discharge stability suitable for the ink jet recording apparatus and the print quality of the recorded image, particularly the quality sufficient in terms of the print density.

  As described above, insoluble colorants, in particular, methods of dispersing various pigment surfaces with resins and surfactants, methods of chemical modification, methods of microencapsulation, and the like have been proposed. There remain problems to be solved such as image density, ejection stability, scratch resistance, marker resistance, and dispersion stability. In particular, there is room for improvement in securing image density and scratch resistance in plain paper recording, and also in achieving both ejection stability.

  Furthermore, Patent Document 9 discloses an ink containing both a pigment having a water dispersibility-imparting group introduced on the pigment surface as a colorant and a pigment having a pigment surface including a water dispersible polymer. This method aims to improve the color developability of plain paper and the abrasion resistance of special paper, but only mixes the pigments with the respective characteristics into the ink, and after the ink has landed It is not satisfactory to compensate for the insufficient properties of each pigment. For this reason, even in the method of using the pigments having these two characteristics in combination, both the color developability and the abrasion resistance are still not sufficient, and there is room for improvement.

  Patent Document 10 and Patent Document 11 disclose inks using pigments in which the relationship between the color material of a microcapsule pigment and a coating resin, which is formed by coating an insoluble color material such as carbon black with organic polymers. ing. Specifically, the color density, high definition, color rendering, transparency, and color developability are improved by adjusting the pigment content and the resin coverage. However, these methods mainly use conventional microencapsulation by phase inversion emulsification, and are characterized in that the resin covering the color material surface is not uniform.

JP-A-10-120955 JP 2001-81372 A Japanese Patent Laid-Open No. 10-195360 JP-A-8-183920 JP-A-5-222109 Japanese Patent Laid-Open No. 7-10911 Japanese Patent Laid-Open No. 9-100303 JP 2003-34770 A International Publication No. 02/066564 Pamphlet JP-A-9-152342 JP 2001-152060 A Color material, 68 [9], 1995, p. 535-541

  The present inventors conducted various studies using the above-described method. As a result, it is possible to stably disperse the coloring material, which is essentially insoluble in water, in the ink, and to achieve excellent image quality (especially in plain paper recording), excellent scratch resistance, and marker resistance. Recognizing that coexistence is the issue to be solved.

  Further, according to the present inventors, the problem described above is that, particularly in the case of plain paper recording, when processing and modifying a water-insoluble color material, the material characteristics and amount of the resin, the amount thereof, and the processing and modification method Appropriate selection and methods are necessary, and it has been confirmed that any of the conventional methods has some adverse effects or insufficient performance.

  Furthermore, in order to solve these problems, the inventors of the present invention appropriately use a method of adhering and fixing a resin to a water-insoluble colorant, and the adhering and fixing state and shape of the adhering and fixing resin, and further water insoluble. It came to the conclusion that it was essential to improve the surface properties of the colorant. Here, in the conventional method described above, it is difficult to make the state of the resin for adhering and fixing the color material surface uniform, and it is not easy to control the adhering and fixing shape and arrangement state. Furthermore, it has been difficult to carry out processing that takes advantage of the characteristics of the resin that adheres and fixes the surface of the color material and the characteristics of the surface of the water-insoluble color material.

  Accordingly, an object of the present invention is to provide a dispersible color material having a sufficiently high dispersion stability using a color material that is essentially insoluble in water, and a simple production method thereof. Furthermore, using the dispersible colorant, not only can it be stably dispersed in the ink, but the resulting printed matter has both excellent image quality (image density), excellent scratch resistance, and marker resistance. It is to provide an aqueous ink jet recording ink. Still another object of the present invention is to provide an ink tank, an ink jet recording apparatus, an ink jet recording method, and an ink jet recorded image using the ink.

  As a means for solving the above problems, the inventors of the present invention maintain high dispersion stability without the need for a surfactant or a polymer dispersant, and also provide a coating shape of an insoluble colorant and surface characteristics of the colorant itself. Thus, a new dispersible color material was obtained.

  That is, the present invention is a dispersible color material in which a color material and chargeable resin pseudo fine particles smaller than the color material are fixed or fused, and the color material itself has a surface charge. Dispersible colorant.

  In addition, the present invention uses an aqueous radical polymerization initiator in a dispersed aqueous solution of a water-insoluble colorant in which at least one polar group is bonded to the surface directly or via another atomic group. A method for producing a dispersible colorant, characterized in that a radically polymerizable monomer is subjected to water-based precipitation polymerization to form chargeable resin pseudo fine particles that are fixed or fused to the surface of the water-insoluble colorant.

  The present invention also provides a water-based ink comprising the dispersible colorant.

  The present invention also provides an ink tank comprising the above water-based ink.

  In addition, the present invention is an ink jet recording apparatus comprising the above water-based ink.

  According to another aspect of the present invention, there is provided an ink jet recording method, wherein an image is formed by an ink jet recording apparatus using the water-based ink.

  In addition, the present invention is an ink jet recording image formed by an ink jet recording apparatus using the water-based ink.

  According to the present invention, the resin fixed and adhered by the method of adhering and fixing the resin to the coloring material, that is, by improving the adhesion and fixing state and shape of the adhered and fixed resin to the surface characteristics of the coloring material. By controlling the arrangement state, it was possible to make use of the characteristics of the resin adhered and fixed to the surface of the color material and the surface of the water-insoluble color material. Therefore, it was possible to provide a dispersible color material having a sufficiently high dispersion stability and a simple production method using a color material that is essentially insoluble in water. Further, the water-based ink suitable for ink-jet recording using the dispersible colorant and not only stably dispersing in the ink but also the obtained printed matter has both excellent image quality and excellent scratch resistance. In addition, it was possible to provide an ink tank, an ink jet recording apparatus, an ink jet recording method, and an ink jet recorded image using water-soluble ink.

  Next, the present invention will be described in detail with reference to the best mode for carrying out the invention. The meaning of the “dispersible colorant” used in the present invention is essentially dispersible in water or an aqueous medium without adding a surfactant or a polymer dispersant for dispersion. It is a color material having self-dispersibility.

(1) Adhesion or fusion of chargeable resin pseudo fine particles to color material and its form and effect The first feature of the present invention is a water-insoluble color material having a surface charge capable of stably dispersing the color material itself. The charged resin pseudo fine particles are fixed or fused. FIG. 1 is a schematic view that characterizes the present invention. Here, FIG. 1 (a) schematically shows a state where the chargeable resin pseudo fine particles 2 are fixed to the water-insoluble colorant 1, and 3 in FIG. 1 (b) indicates a chargeable resin fixed to the surface. This is a portion showing a state where a part of the pseudo fine particle 2-2 is fused. FIG. 1C schematically shows a state in which the flat chargeable resin pseudo fine particles 2-3 are fused.

  In the present invention, when the resin adheres and fixes to the surface of the water-insoluble coloring material, the above-mentioned chargeable resin pseudo fine particles are fixed while maintaining their shape to some extent, and the resin aggregate of the charge resin pseudo particles There is a great feature that is in a fused state in a flat shape. As a result, various effects can be obtained.

  First, the coloring material fixes or fuses the chargeable resin pseudo fine particles, so that the charge of the chargeable resin pseudo fine particles is imparted to the surface of the color material, thereby obtaining a dispersible color material that can be dispersed in water or an aqueous ink medium. . At the same time, the dispersible colorant has excellent adhesion to the recording medium due to the presence of the resin component adhering to the surface. At this time, if the charged resin pseudo fine particles are fixed or fused, which is a characteristic of the dispersible color material of the present invention, rather than simple physical adsorption of the resin component, the charged resin pseudo fine particles are detached from the surface of the color material. Since they are not separated, the dispersible colorant of the present invention is excellent in long-term storage stability.

  Here, the chargeable resin pseudo fine particles in the present invention are resin aggregates in which the resin component is strongly aggregated, and preferably have many physical crosslinks formed therein, and the resin aggregates are in the form of fine particles. Or it has a stable form as a micro-aggregate close | similar to it, and also a flat resin aggregate. Details of the chargeable resin pseudo fine particles will be described later.

  The fixed or fused state in the present invention is due to a strong interaction between the color material surface and the chargeable resin pseudo fine particles, and is considered to be achieved in the following state. FIG. 4 shows a schematic diagram in which the interface between the chargeable resin pseudo fine particles and the color material is enlarged. First, at the interface with the color material, the chargeable resin pseudo fine particles are formed by intertwining polymers composed of various monomer unit compositions. At this time, the polymer has various structures locally, and the surface energy state is distributed. The two interfaces are firmly bonded in that the surface energy resulting from the chemical structure and surface structure of the colorant and the surface energy resulting from the chemical structure and surface structure of the polymer are well matched locally. Furthermore, at the interface where one chargeable resin pseudo fine particle is in contact with the color material, there are a plurality of points where the surface energies as shown by 10 in FIG. 4 are locally matched. It is expected that the fixed state or the fused state is established. In the present invention, a state in which, for example, 25% or more, preferably 35% or more of the surface area of the chargeable pseudo fine particles as shown in FIG. It is not necessary for the chargeable pseudo fine particles and the color material to melt at the interface.

  In particular, since the inside of the charged resin pseudo fine particles has a strong interaction between the constituent polymers, and in some cases, the constituent polymers are entangled with each other to form physical crosslinks. Even when the resin has many hydrophilic groups, the charged resin pseudo fine particles fixed or fused are detached from the coloring material, or the resin component having hydrophilic groups is eluted from the charge resin pseudo fine particles. There's nothing to continue.

  In addition, as a merit that the dispersible colorant of the present invention fixes or fuses the chargeable resin pseudo fine particles, the specific surface area of the dispersible colorant increases depending on the form, and the chargeable resin pseudo fine particles are in many parts. It is possible to distribute the charge on the surface. When the dispersible color material has a high specific surface area, the charge of the chargeable resin pseudo fine particles can be converted to the surface charge of the dispersible color material with extremely high efficiency. That is, the form of the dispersible color material of the present invention is a form in which more surface charges are more efficiently arranged on the surface of the dispersible color material, and is represented by JP-A-8-183920 by a conventional method. High dispersion stability can be imparted even when the substantial acid value or amine value of the resin component is smaller than the form in which such a color material is coated with a resin.

  Even in the case of the dispersible color material of the present invention in which the color material is an organic pigment, a plurality of interaction points of the chargeable resin pseudo fine particles are randomly distributed in the state of being fixed or fused with the color material as described above. Therefore, the chargeable resin pseudo fine particles adhere to several pigment molecules in the pigment crystal (see FIG. 5). Therefore, the “pigment peeling” caused by locally hydrophilizing the pigment molecules described in FIGS. 6A and 6B does not occur in the present invention. Preferably, when an organic pigment is used as a coloring material, the size of the chargeable resin pseudo fine particles is controlled to be smaller than the pigment particles and larger than the pigment molecules, thereby breaking the crystal structure of the pigment. In addition, an organic pigment dispersible colorant imparted with high dispersibility can be obtained.

  In the present invention, the state in which the coloring material “fixes” or “fuses” the chargeable resin pseudo fine particles can be simply confirmed by a technique involving the following three stages of separation. First, the coloring material to be confirmed in the first separation and the other water-soluble component (including the water-soluble resin component) contained in the ink or water dispersion are separated, and then in the second separation, The coloring material and the water-insoluble resin component contained in the precipitate in the first separation are separated. Further, in the third separation, the weakly adsorbed resin component is separated from the dispersible colorant to which the chargeable resin pseudo fine particles are fixed or fused, and the resin component contained in the third separation supernatant. The fixation of the coloring material and the chargeable resin pseudo fine particles is confirmed by performing the determination of the amount and comparison of the precipitate of the second separation and the precipitate of the third separation.

  Specifically, for example, it can be confirmed under the following conditions. Take 20 g of the ink or water dispersion in which the color material is dispersed, adjust the total solid content to about 10%, and use a centrifuge to perform the first test at 12,000 rpm for 60 minutes. Separation. Of the separated substances, the lower sediment containing the coloring material is redispersed in pure water approximately three times the amount of the sediment, and then the second sediment is obtained at 80,000 rpm for 90 minutes. Perform separation. The lower layer containing the color material is subjected to the third separation again under the condition of 80,000 rotations and 90 minutes by redispersing the sediment of the lower layer containing the color material in 3 times the amount of pure water. Re-disperse the sediment in 3 volumes of pure water. The sediment in the second separation and the sediment in the third separation were each taken to have a solid content of about 0.5 g and dried under reduced pressure at 30 ° C. for 18 hours using a scanning electron microscope. Observe at 50,000 times. It was confirmed that the observed dispersible colorant had a plurality of fine particle-like substances or micro-aggregates equivalent thereto attached to the surface, and the same sediments from the second separation and the third separation were the same. If it has this form, it is judged that this coloring material has fixed or fused resin pseudo fine particles. Further, the upper layer supernatant in the third separation was gently taken from the top so that the volume became about half, and the solid content mass was calculated from the mass change before and after drying at 60 ° C. for 8 hours, and 1% If it is less than this, it can be determined that there is no detachment of the resin pseudo fine particles from the dispersible color material, and the dispersible color material fixes or fuses the resin pseudo fine particles.

  The above-described separation conditions are preferable examples, and any other separation method or separation condition can be used as long as the method achieves the purpose of the first separation and the second and third separations described above. It can be applied as a method for determining a dispersible colorant. That is, in the first separation, when there is a color material contained in the ink and the aqueous dispersion and a resin component adsorbed thereto, the purpose is to separate the resin component from the water-soluble component, The purpose is to separate the color material and the resin component fixed or fused to the color material and the other resin component adsorbed to the color material in the second separation. Further, the third separation is intended to confirm that the resin component fixed or fused to the colorant does not desorb. Of course, as long as the separation method achieves the respective purposes in the first, second, and third separations, any other separation method that is known or newly developed may be used. Moreover, it is applicable even if it is at least.

  The second feature of the present invention is that the dispersible colorant is in a state where the water-insoluble colorant 1 is bonded to the chargeable resin pseudo fine particles 2 and 3, or the flat charge resin pseudo fine particles are fused. It is in the point of “distributed alone”.

  As described above, the dispersible colorant of the present invention is essentially a self-dispersible color that can be stably dispersed in water and water-based inks without the aid of other surfactants or polymer dispersants. It is a material. This definition and determination method will be described in detail later. Therefore, the dispersible colorant of the present invention needs to add a polymer dispersant or other resin component or surfactant component that may be released for a long period of time for the purpose of stabilizing the dispersion of the colorant. Absent. As a result, when the dispersible color material of the present invention is used as a water-based ink, the degree of freedom in design regarding components other than the dispersible color material is increased, and for example, recording with high ink permeability such as plain paper is performed. It is also possible to obtain a water-based ink that can obtain a sufficiently high print density even on the medium.

  For example, the self-dispersibility of the dispersible colorant of the present invention is confirmed as follows. The ink or water dispersion in which the color material is dispersed is diluted 10-fold with pure water, and concentrated to the original concentration using an ultrafiltration filter having a molecular weight cut off of 50,000. This concentrated solution is separated by a centrifuge at 80,000 rpm for 90 minutes, and the sediment is taken out and redispersed in pure water. At this time, it is judged that what the sediment can redisperse well has self-dispersibility. Whether or not it is well re-dispersed depends on whether it is uniformly distributed visually, or if there is no noticeable sediment during standing for 1 to 2 hours, or if it is shaken lightly When the dispersion particle diameter is measured by the dynamic light scattering method, it can be comprehensively determined from the fact that the average particle diameter is within twice the particle diameter before the operation.

  As described above, the dispersible colorant of the present invention takes a form having a high specific surface area by fixing or fusing the chargeable resin pseudo fine particles, and has a large amount of charges on its vast surface. In order to achieve excellent storage stability. Therefore, more preferable results can be obtained when the chargeable resin pseudo fine particles are scattered in large numbers and fixed or fused to the color material. In particular, it is desirable that there is a certain distance between the charged resin pseudo fine particles fixed or fused, preferably uniformly distributed, and more preferably the surface of the color material is exposed.

  Such a form is confirmed by observing the dispersible colorant of the present invention with a transmission electron microscope or a scanning electron microscope. A plurality of charged resin pseudo fine particles fixed to the surface of the color material are fixed at a certain distance, or the surface of the color material is exposed between the fixed charged resin pseudo fine particles. I can observe. In addition, the charged resin pseudo fine particles are sometimes close to each other, and in some cases, there may be observed what is fixed and fused, but there is a distance between the charged resin pseudo fine particles as a whole, When there is a portion where the surface of the color material is exposed and these states are distributed, it is considered that the charged resin pseudo fine particles are scattered or fixed or fused to the color material. This will be apparent to those skilled in the art.

  The surface functional group density due to the dispersible colorant of the present invention having a polar group is preferably 250 μmol / g or more and less than 1,000 μmol / g, more preferably 290 μmol / g or more and less than 900 μmol / g in terms of mass average. When the surface functional group density is smaller than this range, the dispersion stability may not be sufficiently maintained when the dispersible colorant is stored for a long period of time. Further, when the surface functional group density is considerably larger than this range, the dispersion stability is sufficiently high. However, when the dispersible colorant of the present invention is applied to the recording medium as an aqueous ink, the color on the recording medium is increased. The material is likely to penetrate and it may be difficult to ensure a high print density. On the other hand, when carbon black is used as the coloring material, the specific gravity of carbon black is high, so that a higher surface functional group density is required to maintain sufficient dispersion stability over a long period of time. Since a high black density is preferred, it is preferably set to 350 μmol / g or more and less than 800 μmol / g.

  In particular, when the surface charge of the dispersible colorant is anionic, the surface functional group density in the present invention is determined as follows, for example. A large excess amount of an aqueous HCl solution is added to the dispersible colorant or water-based ink, and the mixture is precipitated in a centrifuge at 20,000 rpm for 1 hour. The sediment is collected and redispersed in pure water, and then the solid content is measured by a drying method. The redispersed sediment is weighed, and a dispersion obtained by adding a known amount of sodium hydrogen carbonate and stirring the mixture is further sedimented in a centrifuge at 80,000 rpm for 2 hours. The supernatant is weighed, and is obtained as the number of moles per gram of the dispersible colorant by subtracting the known amount of sodium bicarbonate from the neutralized amount obtained by neutralization titration with 0.1 N HCl. In the case of having a cationic group as a polar group, it can be determined by using a similar method using NaOH instead of HCl and ammonium chloride instead of sodium bicarbonate.

(2) Surface charge of water-insoluble color material itself Next, a third feature of the present invention is that the water-insoluble color material itself has a surface charge. “Having a surface charge” means that the water-insoluble colorant itself is “stable without the aid of other surfactants or polymer dispersants” in an aqueous dispersion in which resin fine particles are fixed and dispersed. In other words, the color material itself is self-dispersible.

  In the present invention, not only the chargeable pseudo fine particles but also the water-insoluble colorant itself has a surface charge, so that the effect of coating by fixing or fusing the chargeable resin pseudo fine particles, which is the first feature of the present invention, is achieved. While developing, it is possible to control the affinity and resilience with the paper surface that is the recording medium to be recorded. As a result, the present inventors have been able to improve the point that it was difficult to obtain image density as a result of easy penetration and diffusion into paper, which was a problem of color materials microencapsulated by conventional methods in plain paper recording. As a result of examination, it was confirmed.

  The surface charge of the water-insoluble colorant itself in the present invention is such that after the chargeable resin pseudo fine particles fixed or fused to the water-insoluble colorant in the ink are detached and / or dissolved, the water-insoluble colorant is washed with water. Charge measured by being dispersed in This is different from what is adsorbed by a dispersing agent such as a surfactant or a polymer resin. That is, it indicates that the component to be dispersed is present on the surface of the water-insoluble colorant in a state where it is not easily detached and / or dissolved by an organic solvent or the like, and the polar group is bonded to the surface of the water-insoluble colorant itself. It is characterized by.

Specifically, the water-insoluble colorant of the present invention has a hydrophilic group bonded to the surface directly or through another atomic group and dispersed, and examples of the hydrophilic group include -COOM1, And anionic groups such as —SO ₃ M1 and —PO ₃ H (M1) ₂ (wherein M1 represents a hydrogen atom, an alkali metal, ammonium or organic ammonium).

  Various hydrophilic groups as described above may be directly bonded to the surface of the water-insoluble colorant. Alternatively, another atomic group may be interposed between the pigment particle surface and the hydrophilic group, and the hydrophilic group may be indirectly bonded to the surface of the pigment particle. In this case, it is preferable that the hydrophilic group as described above is bonded to the pigment particle surface via another atomic group.

Here, specific examples of the other atomic group include, for example, a linear or branched alkylene group having 1 to 12 carbon atoms, a substituted or unsubstituted phenylene group, and a substituted or unsubstituted naphthylene group. . Here, as a substituent of a phenylene group and a naphthylene group, an alkyl group (for example, methyl group etc.) is mentioned, for example. Specific examples of combinations of other atomic groups and hydrophilic groups include, for example, —C ₂ H ₄ —COOM1, —Ph—SO ₃ M1, —Ph—COOM1, etc. (where Ph represents a phenyl group). Is mentioned. Particularly Among the above anionic groups -COOM1, colorant having a -SO ₃ M1 group is dispersible at an aqueous medium constituting the ink are preferable than is good.

  Here, the water-insoluble color material in which the hydrophilic group is bonded to the surface of the water-insoluble color material as described above directly or through another atomic group is charged or fused to the water-insoluble color material. Even after detaching and / or dissolving the functional resin pseudo fine particles, this water-insoluble colorant has a characteristic that it can be dispersed in water. Specifically, whether or not the color material itself has a surface charge can be confirmed as follows.

  The dispersible colorant or ink of the present invention is centrifuged in a centrifuge at 12,000 rpm for 60 minutes. After the separation, the lower layer precipitate containing the dispersible colorant is taken out and put into an organic solvent having high solubility in a resin such as toluene or acetone. As a result, the charged resin pseudo fine particles fixed or fused are dissolved and detached from the water-insoluble color material, and the water-insoluble color material itself is present in the organic solvent. This is rotated 80,000 times in a centrifugal separator to precipitate and separate the water-insoluble colorant. The obtained color material is washed and then redispersed in pure water.

  When the water-insoluble colorant that is the core itself has a surface charge as in the dispersible colorant of the present invention, the extracted water-insoluble colorant is redispersed by the above method, and the surface charge can be measured. On the other hand, when it is obtained by adsorbing a dispersing agent such as a surfactant or a polymer resin, the aqueous dispersion or ink obtained by conventional microencapsulation is adsorbed when it is introduced into an organic solvent. Since the components are dissolved and desorbed from the water-insoluble colorant, they are not redispersed in pure water, and the surface charge of the water-insoluble colorant itself in the present invention cannot be measured.

  At this time, in order to re-disperse the water-insoluble colorant, it is naturally preferable that the water-insoluble colorant is finely divided, and in this state, it has a surface charge. Having a surface charge means that it is charged positively or negatively. When dispersed in water, the water-insoluble colorant is surrounded by ions of opposite polarity called an ion stationary phase. Further, on the outer side, ions having opposite polarity or the same polarity as the ion stationary phase are diffusely mixed to form an area like an ion cloud. This is called a diffusion double layer and is neutral as a whole.

  When the water-insoluble color material of the present invention itself is re-dispersed in water and a voltage of + − is applied to the left and right of the aqueous dispersion, the water-insoluble color material becomes part of the ion stationary phase and the diffusion bilayer (inside the slip surface). ) And is attracted to the opposite polarity electrode to move. Here, the potential inside the fine particles including the slip surface, that is, the insoluble colorant is called a zeta potential, and if the water-insoluble colorant has a surface charge, that is, is dispersible, this zeta potential is expressed in several ways. It can be measured. On the other hand, when the zeta potential approaches zero, the fine particles aggregate and are different from those of the present invention.

In the present invention, the surface charge of the water-insoluble colorant is confirmed by measuring the zeta potential described above, and the value is measured by a microscopic electrophoresis measurement method. Here, when water-insoluble color material is dispersed in water and voltage is applied, electrophoresis starts, that is, the ease of movement of water-insoluble color material, which is fine particles, is confirmed with a microscope, and it moves from its moving distance. It measures speed. At this time, the ease of movement of the fine particles is related to the relative dielectric constant and viscosity of the measurement liquid, and is also related to the potential difference at the boundary between the moving fine particles and the liquid. At this time, the measured zeta potential is expressed by the smoluchowski equation:
ζ = 4πη / ε × U × 300 × 300 × 1000 (1)
U is electrophoretic mobility = v / V / L (2)
Ζ = zeta potential (unit: mV)
η = liquid viscosity
v = velocity of fine particles (cm / sec)
V = Voltage (volt)
ε = dielectric constant of solution L = distance between electrodes (cm)
It is.

  In the present invention, after redispersing the water-insoluble coloring material in pure water, after diluting to an appropriate concentration with pure water, while observing the moving speed of the coloring material when a constant electric field is applied with a microscope, The moving speed of the observed object is a value measured by an image processing method.

  In the present invention, the zeta potential measured as the surface charge of the water-insoluble colorant itself is preferably -100 mV to -15 mV as a negative value, and 10 mV to 70 mV as a positive value. If the negative value is larger than this value, the insoluble colorant itself does not have a surface charge that can be stably dispersed. On the other hand, if the positive value is smaller than this value, the insoluble colorant itself does not have a surface charge that can be stably dispersed. Further, by being within the above range, that is, when the surface charge of the water-insoluble colorant is within this range, it is advantageous for the action of the surface charge described later and the sizing agent on the paper surface. On the other hand, when the zeta potential is smaller than −100 mV or larger than 70 mV, the surface charge and the sizing agent on the paper surface may be insufficient and it may be insufficient to improve the water resistance. is there.

(3) Interaction of fixed or fused chargeable resin pseudo fine particles and surface charge of water-insoluble colorant itself As described above in the present invention, the chargeable resin pseudofine particles are fixed or fused to the water-insoluble colorant and dispersed. By doing so, it becomes possible to improve the dispersion stability and improve the scratch resistance due to the binding force of the resin component of the resin fine particles to the paper. Further, the absorption of the solvent obtained and the improvement of the fixability can be realized by the capillary appearance of the ink solvent due to the resin fine particle shape. Furthermore, since the water-insoluble coloring material itself has a surface charge without impairing these characteristics, the surface charge acts on a sizing agent or the like processed on the paper surface in ordinary paper recording. Furthermore, it has been revealed that the image density can be improved by suppressing the penetration and diffusion of the water-insoluble colorant itself into the paper.

  In the present invention, it is desirable that the chargeable resin pseudo fine particles are scattered and fixed or fused to the water-insoluble colorant. In particular, it is preferable to fix or fuse the charged resin pseudo fine particles having a polar group, and there is a certain distance between the fixed resin fine particles, thereby preferably exposing a part of the surface of the water-insoluble colorant. It is desirable that In other words, in the present invention, the surface of the water-insoluble colorant is not entirely covered with the chargeable resin pseudo fine particles because the chargeable resin pseudo fine particles are scattered and fixed or fused. Therefore, there is a portion where the polar group of the water-insoluble color material itself appears, and the effect of the surface charge described above can be expressed more remarkably.

  In other words, since the chargeable resin pseudo fine particles are scattered and fixed, the solid-liquid separation that occurs here is promptly passed through the stage where the ink solvent is rapidly absorbed by the capillary phenomenon between the water-insoluble colorants described above. What is performed makes it easier to express the effect of the surface charge of the water-insoluble colorant itself. This is because the surface charge of the water-insoluble color material acts on the sizing agent on the paper surface, and at the same time, solid-liquid separation occurs quickly, and the dispersion of the color material itself is quickly performed. This is presumed to be due to a decrease in subduction. In other words, the control of image density and the reduction of blurring of characters in plain paper recording can be more advantageous.

  Furthermore, in terms of fixability, a solvent that easily stays on the paper surface while exhibiting the effect of fixing or fusing the chargeable resin pseudo fine particles, and a solvent that promotes absorption into paper fibers by solid-liquid separation, and a water-insoluble colorant The inventors have clarified that the fixability is further improved in order to promote separation from the above. Further, it has been clarified that the binding force of the charged resin pseudo fine particles fixed or fused is exhibited after fixing, and excellent scratch resistance can be obtained. As described above, in the conventional pigment ink, the expression of image density, fixability, and scratch resistance are contradictory, and it has been difficult to achieve both, but this is possible in the present invention. This separates the functions of the surface state of the chargeable resin pseudo fine particles and the insoluble colorant itself that are fixed or fused together, and can achieve both by synergistic effects that assist the effects obtained from each function in both. The present inventors recognize that it has become.

(4) Dispersible colorant and ink in difference from the conventional production method The feature of the dispersible colorant production method of the present invention is that at least one polar group is directly or via other atomic groups on the surface. The combined water-insoluble colorant is dispersed in water, and then a step of aqueous precipitation polymerization of a radical polymerizable monomer using an aqueous radical polymerization initiator is used. Charged resin pseudo fine particles are fixed or fused to the surface of a water-insoluble colorant.

  In the present invention, first, a water-insoluble colorant having at least one polar group bonded to the surface directly or via another atomic group is kept in a well-dispersed state in water. Next, in this aqueous dispersion, an aqueous radical polymerization initiator having high compatibility is used, and the radical polymerizable monomer is polymerized while being precipitated in an aqueous system. The precipitated polymerized particles are a polymer composed of a hydrophilic monomer and a hydrophobic monomer, and are sequentially deposited and fixed or fused to the hydrophobic surface of the water-insoluble colorant that is dispersed in water. This fixation or fusion is different from “adsorption” by a dispersant such as a conventional polymer resin, and is “strong fixation”. Further, in the present invention, it is different from the one manufactured by a solvent-dispersed system like conventional phase inversion emulsification microencapsulation. That is, after dispersing the coloring material in the resin solvent solution, the base is further mixed and dissolved, neutralized to make a self-dispersing resin, and then an aqueous medium containing water as an essential component is mixed and emulsified by dropping or the like. The conventional aqueous dispersion obtained through the so-called phase inversion emulsification method is greatly different from that obtained by the present invention.

  In the present invention, the water-insoluble coloring material having at least one polar group bonded to the surface directly or through other atomic groups is kept in a well-dispersed state in water, and the resin is precipitated and polymerized. The resin pseudo fine particles are fixed or fused on the surface of the water-insoluble colorant in the form of fine particles or flat. As described above, in the present invention, by performing all the steps in water, when the periphery of the water-insoluble colorant is coated with a resin, it becomes a fine particle shape and a flat shape, so that it is formed and coated in a shape having a high specific surface area. Can do. Moreover, it can carry out by covering with resin. That is, according to the present invention, since the resin fine particles are sequentially formed by the above-described method, it is possible to leave the surface of the water-insoluble color material partially, and to fix and coat, and the formation state has a certain degree of uniformity. Obtainable.

  On the other hand, when the conventional phase inversion emulsification method is used, a water-insoluble color material having at least one polar group bonded to the surface directly or through another atomic group is dried, for example, once, and the resin solvent Must be dispersed in solution. At this time, in the conventional method, the resin cannot be fixed and fused in the form of fine particles, and the resin cannot be scattered and fixed or fused. That is, it is difficult to make the water-insoluble colorant part having the surface charge of the water-insoluble color material uniformly scattered to some extent due to the covering shape. Therefore, the surface state and charge state of the obtained aqueous dispersion are different from those of the present invention.

(5) Detailed description of constituent materials and manufacturing method of dispersible colorant in the present invention (water-insoluble colorant)
The water-insoluble colorant, which is an essential component of the ink for ink jet recording of the present invention, will be described. The water-insoluble colorant used in the present invention is a water-insoluble colorant such as a hydrophobic dye, an inorganic pigment, an organic pigment, a metal colloid, or a colored resin particle, and the colorant itself can have a surface charge. Any material can be used as long as it is capable of fixing or fusing the charged resin pseudo fine particles in the present invention and stably dispersing in water. Preferably, a colorant having a dispersed particle diameter in the range of 0.01 to 0.5 μm (10 to 500 nm), particularly preferably 0.03 to 0.3 μm (30 to 300 nm) is used. . The dispersible color material of the present invention using the color material dispersed in this range is a dispersible color material having high coloring power and high weather resistance. In addition, let this dispersion | distribution particle size be the cumulant average value of the particle size measured by the dynamic light confusion method.

  Examples of the inorganic pigment that can be effectively used as a coloring material in the present invention include carbon black, titanium oxide, zinc white, zinc oxide, tripone, iron oxide, cadmium red, molybdenum red, chrome vermilion, molybdate orange, Yellow lead, chrome yellow, cadmium yellow, yellow iron oxide, titanium yellow, chromium oxide, pyridian, cobalt green, titanium cobalt green, cobalt chrome green, ultramarine blue, ultramarine blue, bitumen, cobalt blue, cerulean blue, manganese violet, cobalt Examples include violet and mica.

  Examples of organic pigments that can be effectively used in the present invention include azo, azomethine, polyazo, phthalocyanine, quinacridone, anthraquinone, indigo, thioindigo, quinophthalone, benzimidazolone, Various pigments such as indoline and isoindolinone are listed.

  Other organic water-insoluble colorants that can be used in the present invention include, for example, azo, anthraquinone, indigo, phthalocyanine, carbonyl, quinoneimine, methine, quinoline, nitro, and other hydrophobic materials. Sexual dyes. Of these, disperse dyes are particularly preferable.

(Surface charge treatment of water-insoluble colorant)
In the present invention, the water-insoluble colorant as described above is used and processed so as to have a surface charge. That is, it is bonded to the surface of the water-insoluble coloring material directly or via another atomic group. Here, the atomic group bonded to the surface of the water-insoluble colorant is preferably a polar group, and either an anionic group or a cationic group is appropriately selected as the polar group.

Examples of the anionic group, for _{example, -COOM, -SO 3 M, -PO} 3 HM, -PO 3 M 2, -SO 2 NH 2, -SO 2 NHCOR ( where, M in the formula is a hydrogen atom, an alkali metal And R represents an alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted naphthyl group. Here, as a substituent of a phenyl group and a naphthyl group, a C1-C6 linear or branched alkyl group is mentioned, for example. In the present invention, among these, in particular, -COOM, is suitable for -SO ₃ M is bonded to the water-insoluble coloring material surface.

  “M” in the hydrophilic group includes, for example, lithium, sodium, potassium and the like as an alkali metal, and examples of organic ammonium include mono to trimethyl ammonium, mono to triethyl ammonium, and mono to trimethanol ammonium. Is mentioned.

  Examples of a method for obtaining these water-insoluble color materials having an anionic surface charge include a method of oxidizing the color material with sodium hypochlorite as a method for introducing -COONa into the color material surface. Of course, the present invention is not limited to these.

  In particular, carbon black generally has a hydrophobic surface. In particular, carbon black produced by the furnace method has few hydrophilic groups such as carboxyl groups and hydroxyl groups on the pigment surface, and the surface is hydrophobic. It is sex. In order to make the surface of such carbon black hydrophilic, it is preferable to impart a hydroxyl group or a marine group by oxidation treatment. On the other hand, even with the same carbon black, gas black produced by Degussa, etc. produced in an environment where oxygen is relatively present has a hydrophilic group on the surface, and these may be used. Examples of such gas black include Degussa FW1, FW2, and FW200.

  The degree of oxidation of the carbon black surface is evaluated as the volatile content (%) of carbon black. Normally, when carbon black is heated to about 1,000 ° C. under vacuum, a gas corresponding to the type of functional group present on the surface is generated, and the total amount of the gas or the gas species is analyzed. The type and amount of surface functional groups can be known. Moreover, it turns out that it is carbon which has a large amount of hydrophilic groups, so that the sum total of heating weight reduction amount is high.

  In the present invention, the weight loss by heating is preferably 2% by mass or more and 20% by mass or less. When the amount is less than the above range, sufficient dispersion stability may not be obtained due to the low hydrophilicity of the color material surface. On the other hand, if the amount is larger than the above range, there may be a case where sufficient image density, bleed or the like cannot be obtained.

  A wet oxidation method is mentioned as a method which can raise the oxidation degree of the surface of carbon black. In this method, carbon black is impregnated in the aqueous phase, an oxidizing agent such as peroxodiacid or peroxodiacid salt is added, and the reaction is performed at about 60 to 90 ° C. to perform surface oxidation. More specifically, such wet oxidation on carbon black can be carried out by the method described in JP-A-2003-183539. As another wet oxidation method, there is a method of oxidizing using hypochlorous acid such as sodium hypochlorite and potassium hypochlorite as described in JP-A-2003-96372. At this time, more uniform oxidation is possible when relatively hydrophilic carbon such as gas black and acidic black is used as the carbon to be oxidized.

  As the cationic group, for example, a quaternary ammonium group is preferable, and more preferable examples include the quaternary ammonium groups listed below. In the present invention, any of these is bonded to the color material surface. Is preferred.

  As a method for producing a water-insoluble color material to which a cationic group is bonded as described above, for example, as a method for bonding an N-ethylpyridyl group having the structure shown below, for example, a color material is 3-amino-N- Although the method of processing with ethyl pyridinium bromide is mentioned, of course, this invention is not limited to this.

In the present invention, the polar group as mentioned above may be bonded to the surface of the pigment through another atomic group. Examples of other atomic groups include an alkyl group having 1 to 12 carbon atoms, a phenyl group which may have a substituent, or a naphthyl group which may have a substituent. Specific examples of the hydrophilic group described above is bonded to the surface of the colorant via other atomic group, for _{example, -C 2 H 4 COOM, -PhSO} 3 M, -C 5 H 10 NH 3 + , etc. Of course, the present invention is not limited to these.

  Examples of a method for introducing a polar group on the surface of the color material include a method in which p-aminobenzenesulfonic acid is diazotized in the color material and reacted with the color material. However, the present invention is not limited to these methods. In introducing the hydrophilic functional group by diazotization as described above, it is desirable that the coloring material does not have a primary amine in order to suppress side reactions.

(Chargeable resin pseudo fine particles)
The chargeable resin pseudo fine particles, which are another constituent of the dispersible color material of the present invention, are substantially insoluble in water and are smaller than the color material to be fixed or fused, and have a sufficient degree of polymerization. Is defined as a fine body formed by agglomeration of resin components having a high particle size, and what is fixed as its form is pseudo-spherical, and what is fused is a pseudo-flat spherical shape. Moreover, it is a minute body in which the sizes of the plurality of chargeable resin pseudo fine particles are aligned within a certain range. It is preferable that the resin components constituting the chargeable resin pseudo fine particles are physically or chemically cross-linked with each other. Whether or not the resin components constituting the chargeable resin pseudo fine particles are cross-linked with each other can be confirmed by the following method, for example. The resin component constituting the chargeable resin pseudo fine particles is estimated in advance by a known analysis method, and a linear polymer having the same chemical structure (or the same monomer unit composition) is synthesized by solution polymerization, and the polymer When the solubility of the chargeable resin pseudo fine particles is lower than the solubility of the polymer when the chargeable resin pseudo fine particles and the polymer are respectively immersed in an organic solvent that is a good solvent and their solubility is compared, It is confirmed that the inside of the chargeable resin pseudo fine particles is crosslinked.

  In another preferred embodiment, when the dispersed particle diameter of the charged resin pseudo fine particles in water can be measured by, for example, a dynamic light scattering method, the average value of the dispersed particle diameter is preferably It is desirable to be in the range of 10 nm or more and 200 nm or less. Furthermore, from the viewpoint of long-term storage stability of the dispersible color material, it is more preferable that the polydispersity index of the dispersed particle diameter is suppressed to less than 0.2. When the average value of the dispersed particle diameter is larger than 200 nm or when the polydispersity index is larger than 0.2, the original purpose of finely dispersing and stabilizing the coloring material may not be sufficiently achieved. Further, when the average value of the dispersed particle diameter is smaller than 10 nm, the form as the chargeable resin pseudo fine particles cannot be sufficiently maintained, and the resin is easily dissolved in water, so that the merit of the present invention cannot be obtained. There is a case. On the other hand, in the range of 10 nm or more and 200 nm or less, the particle size is smaller than the color material particles themselves, so that the dispersion stabilization of the color material by the fixing of the chargeable resin pseudo fine particles of the present invention is effectively expressed. The The above preferable aspect is the same when the dispersed particle size of the charged resin pseudo fine particles is not measurable. In this case, for example, the average diameter of the charged resin pseudo fine particles in the electron microscope observation is Is considered to be a preferred range or a range equivalent thereto.

  When the colorant is an organic pigment, in addition to the above range, as described above, the charged resin pseudo fine particles are smaller than the primary particle of the pigment and larger than the pigment molecule. This is desirable because a dispersible colorant having a very stable structure and high dispersibility can be obtained.

  In the present invention, the chargeability in the chargeable resin pseudo fine particles fixed or fused to the water-insoluble colorant means that the functional group is ionized in some form in the aqueous medium, and preferably the charge is charged. A state in which self-dispersion is possible depending on sex. Therefore, as to whether it is a chargeable resin pseudo fine particle, the surface zeta potential of the chargeable resin pseudo fine particle is measured by a publicly known and arbitrary method. Calculate, confirm the dependence of dispersion stability on the electrolyte concentration by adding an electrolyte to the aqueous dispersion of the charged resin pseudo fine particles, or analyze the chemical structure of the charged resin pseudo fine particles by a known method This can be achieved by any method of examining the presence or absence of a functional group.

  In a preferred embodiment, the chargeable resin pseudo fine particles are obtained by having a polar group. Since the chargeable resin pseudo fine particles have polar groups, high self-dispersion stability can be obtained. The polar group is preferably an anionic group or a cationic group. Further, it is desirable that the polar group possessed by the chargeable resin pseudo fine particles and the polar group chemically bonded to the water-insoluble colorant itself have the same polarity. As a result, the chargeable resin pseudo fine particles are firmly fixed without being repelled in a state where the water-insoluble colorant is stably dispersed. Further, an aqueous dispersion in which the chargeable resin pseudo fine particles are fixed or fused can exist stably.

  Here, the resin component constituting the chargeable resin pseudo fine particles may be any resin component such as any commonly used natural or synthetic polymer, or a polymer newly developed for the present invention. Can be used without limitation. Examples of resin components that can be used include acrylic resins, styrene / acrylic resins, polyester resins, polyurethane resins, polyurea resins, polysaccharides, and polypeptides. In particular, from the standpoint that it can be used generally and functional design of resin fine particles can be easily performed, a polymer or copolymer of a monomer component having a radical polymerizable unsaturated bond, such as acrylic resin and styrene / acrylic resin, is used. It can be preferably used.

  In the present invention, a monomer having a radical polymerizable unsaturated bond (hereinafter referred to as a radical polymerizable monomer or simply a monomer) is preferably used. For example, the following can be mentioned. Classified as hydrophobic monomers, for example, methyl acrylate, ethyl acrylate, isopropyl acrylate, acrylate-n-propyl, acrylate-n-butyl, acrylate-t-butyl, benzyl acrylate, methyl methacrylate (Meth) acrylic acid esters such as ethyl methacrylate, isopropyl methacrylate, methacrylate-n-propyl, methacrylate-n-butyl, isobutyl methacrylate, tert-butyl methacrylate, tridecyl methacrylate, benzyl methacrylate, etc. Styrene monomer such as styrene, α-methyl styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-tert-butyl styrene, etc .; itaconate such as benzyl itaconate; dimethyl maleate, etc. Such as Esters; fumaric acid such as fumaric acid esters such as dimethyl acrylonitrile, methacrylonitrile, vinyl acetate, and the like. In the present invention, (meth) acrylic acid means methacrylic acid and acrylic acid.

  In addition, those classified as the following hydrophilic monomers are also preferably used. For example, monomers having an anionic group include, for example, monomers having a carboxyl group such as acrylic acid, methacrylic acid, crotonic acid, ethacrylic acid, propylacrylic acid, isopropylacrylic acid, itaconic acid, fumaric acid, and the like. A monomer having a sulfonic acid group such as a salt, styrene sulfonic acid, sulfonic acid-2-propylacrylamide, acrylic acid-2-ethyl sulfonate, methacrylic acid-2-ethyl sulfonate, butyl acrylamide sulfonic acid, and the like; And monomers having a phosphonic acid group such as ethyl methacrylate-2-phosphonate and ethyl acrylate-2-phosphonate. Among these, it is particularly preferable to use acrylic acid and methacrylic acid.

  Monomers having a cationic group include monomers having a primary amino group such as aminoethyl acrylate, aminopropyl acrylate, methacrylamide, aminoethyl methacrylate, aminopropyl methacrylate, and the like, and methylaminoethyl acrylate. Secondary amino groups such as methylaminopropyl acrylate, ethylaminoethyl acrylate, ethylaminopropyl acrylate, methylaminoethyl methacrylate, methylaminopropyl methacrylate, ethylaminoethyl methacrylate, ethylaminopropyl methacrylate, etc. Monomers having dimethylaminoethyl acrylate, diethylaminoethyl acrylate, dimethylaminopropyl acrylate, diethylaminopropyl acrylate, dimethylaminoethyl methacrylate, Monomers having a tertiary amino group such as diethylaminoethyl silylate, dimethylaminopropyl methacrylate, diethylaminopropyl methacrylate, dimethylaminoethyl methyl chloride salt, dimethylaminoethyl methyl chloride salt, dimethylaminoethyl acrylate Examples thereof include monomers having a quaternary ammonium group such as benzyl chloride salt and dimethylaminoethyl benzyl chloride salt, and various vinylimidazoles.

  Specific examples of the nonionic hydrophilic monomer include monomers having a radical polymerizable unsaturated bond and a hydroxyl group exhibiting strong hydrophilicity in the structure at the same time. Hydroxyethyl (meth) acrylate, hydroxylpropyl (meth) acrylate, and the like are classified into this. In addition, various known or novel oligomers and macromonomers can be used without limitation.

  In particular, the chargeable resin pseudo fine particles are more preferably composed of a copolymer of monomer components including at least one kind of hydrophobic monomer and at least one kind of hydrophilic monomer among those described above. It is preferable at the point which obtains the ink for water-based inkjet recording which has a printing characteristic. That is, when preparing resin fine particles, for example, various types of resin fine particles fixed to the surface of the colorant depending on many control factors such as the type and concentration of the polymerization initiator to be used, the type of monomer to be constituted, and the copolymerization ratio The properties and the like can be appropriately controlled. At this time, at least one kind of good fixing property and heat stability to the water-insoluble colorant can be obtained by using at least one kind of hydrophobic monomer. By using this hydrophilic monomer, good form control and dispersion stability can be imparted, respectively. Therefore, by using these monomers at the same time, it is possible to obtain resin fine particles that are always well fixed to the colorant and have good dispersion stability. In addition to satisfying the above conditions, the water-insoluble colorant of the present invention and / or the resin fine particles fixed to the colorant can be further selected by appropriately selecting the monomer species and copolymerization ratio constituting the resin fine particles. Can add functionality.

  It is also a preferred embodiment that the hydrophobic monomer contains at least a monomer having a methyl group at the α-position and having a radical polymerizable unsaturated double bond. By fixing resin fine particles using a radically polymerizable monomer having a methyl group at the α-position, particularly in a thermal ink jet method in which ink is ejected by thermal energy, the ejectability of an aqueous inkjet recording ink containing a water-insoluble colorant Becomes very good. The reason for this is not clear, but resins using a radically polymerizable monomer having a methyl group at the α-position cause depolymerization at high temperatures, and therefore have a methyl group at the α-position when thermal energy is applied to the ink. Since the resin composed of the monomer component undergoes depolymerization and sticking into the discharge port is less likely to occur, it is considered that the discharge property is improved.

  Furthermore, when fusing the flat charged resin pseudo fine particles, at least one kind of hydrophobic monomer, at least one kind of nonionic hydrophilic monomer, and at least one kind of anionic or cationic, as described above. It is a desirable mode to consist of a copolymer of monomer components including a hydrophilic monomer. At this time, by using at least one kind of hydrophobic monomer, it is possible to form a good fusing property and thermal stability to the colorant, and by using at least one kind of nonionic hydrophilic monomer, the chargeability. Good dispersion stability can be imparted to each of the resin pseudo fine particles by forming a flat spherical shape and dispersion stability using at least one kind of anionic or cationic hydrophilic monomer.

  Moreover, it is also a preferable form to contain at least an acrylic acid alkyl ester compound and a methacrylic acid alkyl ester compound (hereinafter referred to as a (meth) acrylic acid alkyl ester compound) as the hydrophobic monomer. The (meth) acrylic acid alkyl ester compound has good adhesion to the hydrophobic surface of the water-insoluble colorant, and at the same time, is excellent in copolymerization with the hydrophilic monomer component, and has the surface properties of the resin fine particles. From the viewpoints of uniformity and uniform fixation / fusion to a water-insoluble colorant, preferable results are given.

  Furthermore, it is particularly preferable that at least one selected from benzyl methacrylate or methyl methacrylate is included among the preferred hydrophobic monomers described above. In addition to the above preferred reasons, the two types of monomers impart preferable heat resistance and transparency to the resin fine particles, and the water-based inkjet recording ink containing the water-insoluble color material to which the resin fine particles are fixed has a coloring property. Excellent ink.

  In addition, when the flat charged resin pseudo fine particles are fused, the nonionic hydrophilic monomer is specifically a structure such as hydroxyethyl (meth) acrylate or hydroxypropyl (meth) acrylate. Monomers having a radically polymerizable unsaturated bond and a hydroxyl group having strong hydrophilicity at the same time, methoxypolyethylene glycol (meth) acrylate, ethoxymethoxypolyethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, polypropylene ( Monomers containing an alkylene oxide group such as (meth) acrylate, other known or novel various oligomers, macromonomers, and the like can also be used without limitation. In particular, the alkylene oxide group-containing monomer is excellent in copolymerizability with the hydrophobic monomer component, and gives favorable results from the viewpoints of uniformity of the surface property of the chargeable resin pseudo fine particles and adhesion to a colorant. .

  In addition, the water-insoluble colorant and / or the colorant of the present invention can be fixed or fused by appropriately selecting the monomer species constituting the chargeable resin pseudo fine particles such as the hydrophobic monomer and the hydrophilic monomer and the copolymerization ratio. The property of the charged resin pseudo fine particles can be controlled. However, when the charge resin pseudo fine particles are fixed to the colorant, the glass transition temperature of the copolymer component contained in the charge resin pseudo fine particles is low. It is also a preferable form to control the temperature so that it is −40 ° C. or higher and 60 ° C. or lower. Moreover, when forming a flat fusion | fusion, it is also a preferable form to control so that the glass transition temperature of a copolymer component may be -100 degreeC or more and 0 degrees C or less. By setting the glass transition temperature within this range, the charged resin pseudo fine particles fixed or fused according to the present invention can have a desired shape and can be more firmly fused with the colorant. .

In order to obtain such a chargeable resin pseudo fine particle, a monomer group that is known to have a low glass transition temperature of a homopolymer obtained from the monomer among the monomer groups that are preferably used is selected and used. For example, it is also a preferable embodiment to use acrylic acid-n-butyl and acrylic acid as monomers in an appropriate ratio. It is also another preferred embodiment to use ethyl methacrylate and methacrylic acid as monomers in an appropriate ratio. In particular, when forming a flat fusion, a monomer group that is known to have a low glass transition temperature of a homopolymer obtained from the monomer among the monomer groups that are preferably used is selected and used. For example, examples of the hydrophobic monomer include those represented by the following (1).
_{CH 2 = CR-COOC n H} (2n + 1) (1)
(In (1) above, R represents H or CH ₃ and 3 ≦ n ≦ 10.)

  Specifically, (meth) acrylic acid propyl, (meth) acrylic acid isopropyl, (meth) acrylic acid-n-butyl, (meth) acrylic acid-t-butyl, (meth) acrylic acid isobutyl, (meth) acrylic Pentyl acid, hexyl (meth) acrylate, heptyl acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, (meth) acrylate-2-ethylhexyl, (meth) acrylic acid -2-ethylbutyl, dodecyl (meth) acrylate, 3,3-dimethyl-2-butyl methacrylate, 1,1-diethylpropyl methacrylate, isodecyl methacrylate, and 1-methylbutyl methacrylate. Further, examples of the hydrophilic monomer include monomers containing the above-described alkylene oxide group.

  The glass transition temperature of the chargeable resin pseudo fine particles can be measured by a commonly used differential scanning calorimetry. For example, in this invention, the value measured using DSC822e by a METTTLER company is used. The water-insoluble colorant obtained by fixing or fusing the resin fine particles having a glass transition temperature containing the copolymer component as described above has a high film-forming property imparted to the chargeable resin pseudo fine particles, A strong colored film can be formed by forming a film with a color material adjacent on the recording paper. Accordingly, not only high scratch resistance is imparted to the printed matter in plain paper recording, but also a printed matter having excellent scratch resistance even on a glossy medium that is extremely disadvantageous in scratch resistance.

  Further, in the case of using a pigment as the water-insoluble colorant, the ratio of the pigment to the chargeable resin pseudo fine particles (resin mass / pigment mass, expressed as B / P) is in the range of 0.1 to 4.0. This is also a desirable embodiment in order to improve the scratch resistance of the printed matter. By setting the B / P ratio to be 0.1 or more, excellent scratch resistance can be imparted to the printed matter by improving the adhesion between the color materials and between the color material and the recording medium. In particular, when a water-insoluble colorant formed by fixing or fusing the above-mentioned chargeable resin pseudo fine particles comprising a copolymer component having a glass transition temperature as described above is used, the film forming property thereof Can be expressed more effectively, resulting in an increase in scratch resistance on glossy paper. When B / P is significantly larger than 4.0, the ink becomes highly viscous as a whole, and the ejection stability as the ink for inkjet recording may be impaired. In addition, since the amount of resin is extremely large relative to the color material, the coloring property of the color material on the recording medium is hindered, and the print density of the printed matter may not be sufficiently obtained. B / P is controlled within the above-described range of 0.1 to 4.0, and further, the ink for water-based inkjet recording has both excellent scratch resistance and ejection stability due to the correlation with the surface charge of the coloring material. It can be. The resin mass as used herein refers to the total amount of the resin fine particles contained in the water-based inkjet recording ink of the present invention, but also includes resin components that are clearly strongly adsorbed on the color material surface. There is a case. However, the water-soluble resin component that can be easily separated from the coloring material is not included.

  The above-mentioned B / P can be generally obtained by a differential thermal mass measurement method, but in the present invention, it is a value measured and calculated by TGA / SDTA851 manufactured by METTTLER. In the present invention, the sediment obtained by centrifuging the ink for water-based inkjet recording of the present invention at 80,000 rpm for 2 hours is dried, weighed, and heated in a nitrogen atmosphere or air. The mass change before and after the decomposition temperature of each of the coloring material and the resin component was determined, and B / P was calculated.

  The chargeable resin pseudo fine particles may be composed of a copolymer of monomer components including at least one type of hydrophobic monomer and at least one type of hydrophilic monomer, and may include at least an anionic monomer as the hydrophilic monomer. Is a preferred form. In particular, by including an anionic monomer, more anionic groups can be introduced into the chargeable resin pseudo fine particles, and the surface functional group density of the colorant is controlled to a preferable value as described above. It is also effective. In addition, by including the anionic monomer, it is possible to obtain a dispersible colorant exhibiting high dispersion stability particularly in a high pH region to a medium pH region.

  The anionic monomer is not particularly limited as long as it is a monomer having a functional group exhibiting anionic property in water. From the viewpoint of copolymerization with other monomer components, versatility, anionic strength, etc., acrylic Acid, methacrylic acid, p-styrenesulfonic acid and salts thereof are particularly preferably used.

  Furthermore, in the above-described configuration, a configuration including at least a cationic monomer as a hydrophilic monomer is a preferable form capable of obtaining a dispersible colorant exhibiting high dispersion stability particularly in a medium pH region to a low pH region. The cationic monomer is not particularly limited as long as it is a monomer having a functional group that exhibits a cationic property in water, but among the radical polymerizable monomers described above, those mentioned as monomers having a cationic group are preferably used. .

(Synthesis of chargeable resin pseudo fine particles and fixation or fusion to water-insoluble colorant)
The method for synthesizing the chargeable resin pseudo fine particles and the method for fixing or fusing to the water-insoluble colorant are known in general procedures and methods for self-dispersing resin fine particles. It can be carried out by a composite method of the conductive resin fine particles and the color material.

  However, as a result of intensive studies, the present inventors have obtained a dispersible color material having a color material having a surface charge and charged resin pseudo fine particles smaller than the color material, which is a feature of the present invention. The inventors have invented a simple method for producing a dispersible colorant characterized in that the material and the chargeable resin pseudo fine particles are fixed or fused. Hereinafter, a method for producing a dispersible colorant of the present invention, which is preferably implemented in the present invention, will be described.

  As a result of the study by the present inventors, the water-insoluble colorant, which is dispersed in a state in which the charged resin pseudo fine particles having the above-described characteristics are fixed or fused, and is dispersed alone, is subjected to an aqueous precipitation weight under the following conditions. It became clear that it can be manufactured very simply by applying the legal method. That is, first, an aqueous dispersion in which a water-insoluble colorant having a surface charge on its surface is dispersed in water by the production method described above is obtained. Next, in this aqueous dispersion, the chargeable resin pseudo fine particles are fixed or fused by a step of aqueous precipitation polymerization of a radical polymerizable monomer using an aqueous radical polymerization initiator. Through this process, the chargeable resin pseudo fine particles synthesized in the water-based precipitation polymerization process are firmly fixed in a uniform and scattered state on the water-insoluble colorant. Excellent in properties. In the aqueous precipitation polymerization process, the characteristics of the chargeable resin pseudo fine particles can be easily controlled to the preferred form as described above, and also in this case, with the water-insoluble colorant that is a feature of the present invention. Adherence and fusion can be achieved satisfactorily. Hereinafter, preferred embodiments of the manufacturing method will be described in detail.

(Dispersion of water-insoluble colorant)
First, an aqueous dispersion in which a coloring material having a charge on its surface, which is preferably used in the present invention as described above, is dispersed in water. About the preparation method of this water dispersion, it processes so that it may have a surface charge as mentioned above. That is, it is bonded directly to the surface of the water-insoluble coloring material or via another atomic group, and is stably dispersed in water as shown in FIG.

  In the process of converting the water-insoluble colorant into an aqueous dispersion by the above-described treatment, the colorant preferably has an average dispersed particle diameter in the range of 0.01 μm to 0.5 μm (10 nm to 500 nm), particularly preferably. Disperses in the range of 0.03 μm to 0.3 μm (30 nm to 300 nm). The dispersed particle diameter in this process largely reflects the dispersed particle diameter of the dispersible colorant to be obtained, and the above range is preferable from the viewpoint of the above-mentioned coloring power, image weather resistance, and dispersion stability.

  The dispersion particle size distribution of the water-insoluble colorant used in the present invention is preferably monodispersed as much as possible. In general, the particle size distribution of the dispersible colorant obtained by fixing or fusing the chargeable resin pseudo fine particles is the particle size distribution of the dispersed aqueous solution before the polymerization step shown in FIG. However, it basically depends on the particle size distribution of the dispersed aqueous solution. It is also important to narrow the particle size distribution of the color material in order to reliably induce fixation due to heteroaggregation of the color material and the chargeable resin pseudo fine particles. According to the study by the present inventors, when the polydispersity index of the color material is in the range of 0.25 or less, the dispersion stability of the obtained dispersible color material becomes excellent.

  Here, the particle size of the colorant in a dispersed state varies depending on various measurement methods. In particular, the organic pigment is very small in the case of spherical particles, but in the present invention, the particle size is dynamically changed by ELS-8000 manufactured by Otsuka Electronics Co., Ltd. The average particle diameter and polydispersity index determined by measuring with the light scattering method as the principle and by cumulant analysis are used.

(Radical polymerization initiator)
As the radical polymerization initiator used in the present invention, any general water-soluble radical polymerization initiator can be used. Specific examples of the water-soluble radical polymerization initiator include persulfate. Or the redox initiator by the combination of a water-soluble radical polymerization initiator and a reducing agent may be sufficient. Specifically, it is designed and used so as to obtain an optimal combination in consideration of the characteristics such as the colorant and the monomer listed above. Desirably, a polymerization initiator that gives a polymerization initiator residue having the same charge as the surface characteristics of the water-insoluble colorant to which the chargeable resin pseudo fine particles to be obtained are fixed or fused is selected. That is, for example, when the water-insoluble colorant having an anionic group is obtained, the surface charge can be obtained more efficiently by selecting the initiator residue that is neutral or anionic. . Similarly, when the water-insoluble colorant having a cationic group is obtained, it is preferable to select one having an initiator residue that is neutral or cationic.

(Radically polymerizable monomer)
The radical polymerizable monomer used in the production method of the present invention is a component constituting the chargeable resin pseudo fine particles through the aqueous precipitation polymerization. Here, the radically polymerizable monomer is appropriately selected depending on the characteristics of the chargeable resin pseudo fine particles having the obtained performance and the characteristics of the aqueous dispersion obtained by fixing the chargeable resin pseudo fine particles to the surface of the water-insoluble colorant. That's fine. In the production method of the present invention, any conventionally known radically polymerizable monomer or a radically polymerizable monomer newly developed for the present invention can be used. Specific examples include various monomers having the radical polymerizable unsaturated bond as described above.

(Aqueous precipitation polymerization)
Subsequently, a preferred embodiment of aqueous precipitation polymerization, which is a step of synthesizing the chargeable resin pseudo fine particles, which is a feature of the present invention, and fixing it to the water-insoluble colorant will be described. FIG. 2 is a process diagram schematically showing a process flow of the manufacturing method. First, as shown in FIG. 2A, an aqueous dispersion in which a water-insoluble colorant is dispersed in an aqueous solution using a dispersant 3 is prepared. Next, the temperature of the dispersion prepared in FIG. 2A is raised while stirring, and the monomer component 4 is added to the dispersion together with, for example, the aqueous radical polymerization initiator aqueous solution 5 (see FIG. 2B). ). The added aqueous radical polymerization initiator cleaves when heated to generate radicals, and among the monomer components added to the aqueous dispersion, a hydrophobic monomer and an aqueous phase in which a trace amount is dissolved in the aqueous phase. Contributes to the reaction with the water-soluble monomer. As the reaction proceeds, the oligomers produced by the polymerization reaction of the monomer components become insoluble in water and precipitate from the aqueous phase, but the oligomers precipitated at this time do not have sufficient dispersion stability. Self-dispersing resin fine particles are formed (see FIG. 2C). FIG. 3 is a schematic diagram illustrating a process until the monomer 4 is polymerized to produce a dispersible colorant. When the reaction of the monomer 4 proceeds as described above, the oligomer 7 generated by the polymerization reaction of the monomer component becomes insoluble in water and precipitates from the aqueous phase (8 in the figure). Since they do not have stability, they are united to form the charged resin pseudo fine particles 2 having sulfonic acid groups. Further, the chargeable resin pseudo fine particles 2 cause hetero-aggregation with the hydrophobic surface of the color material 1 in the dispersed aqueous solution as a nucleus, and the resin component constituting the color material surface and the charge resin pseudo fine particles 2 is caused by hydrophobic interaction. Adsorbs strongly. At this time, the polymerization reaction continues to proceed inside the chargeable resin pseudo fine particles 2, and changes to a more energy-stable form while increasing the adsorption point with the color material 1. At the same time, since the physical cross-links are highly formed inside the chargeable resin pseudo fine particles, the form that adsorbs the color material 1 most stably is fixed and is in a fixed state. On the other hand, the coloring material 1 is stabilized by fixing a plurality of chargeable resin pseudo fine particles 2 and the dispersant 3 in an equilibrium state is detached from the coloring material surface (FIG. 2D and FIG. 2). 3).

  The self-dispersing resin fine particles are further stabilized by heteroaggregating with the water-insoluble colorant dispersed in the aqueous solution as a nucleus. Therefore, the water-insoluble color material used in the present invention is obtained in a form in which a plurality of chargeable resin pseudo fine particles 6 are fixed or fused to the surface of the water-insoluble color material for one dispersion unit of the color material. Further, in this process in which precipitation accompanying polymerization and fixation or fusion to the color material proceed simultaneously, the self-dispersing resin fine particles are aggregated at a stage that does not have sufficient dispersion stability. A strong intermolecular force and hydrophobic interaction act between the pseudo fine particles and the coloring material, and the chargeable resin pseudo fine particles are adsorbed in a more stable form with respect to the surface shape of the coloring material, and are strongly colored. Adhering or fusing to the material. Through the process described above, the water-insoluble colorant having the above-described configuration is easily formed (see FIG. 2D).

  The polymerization reaction conditions vary depending on the properties of the polymerization initiator, monomer, and the like to be used. For example, the reaction temperature is 100 ° C. or lower, preferably in the range of 40 to 80 ° C. The reaction time is 1 hour or longer, preferably 6 to 30 hours. The stirring speed during the reaction is 50 to 500 rpm, preferably 150 to 400 rpm. Depending on the properties of the polymerization initiator, monomer, and water-insoluble colorant used, a small amount of a protective colloid substance of chargeable resin pseudo fine particles may be previously placed in the polymerization system. Thereby, the particle diameter of the chargeable resin pseudo fine particles may be adjusted to be smaller. Examples of the protective colloid substance include water-soluble polymer resins. In the method for producing a dispersible color material of the present invention, since the color material itself has a surface charge that can be stably dispersed, the above-described steps are essentially performed without the need for a surfactant or a polymer dispersant. However, before or during the process of water-based precipitation polymerization of the radically polymerizable monomer using an aqueous radical polymerization initiator, the water-soluble polymer resin as described above is added to the polymerization system and fixed. It became clear that the size of the chargeable resin pseudo fine particles is smaller and uniform, and preferable results are obtained from the viewpoint of increasing the resin mass / pigment mass and the B / P ratio. At this time, the addition amount is preferably 0.05 to 5% by mass, and more preferably 0.1 to 2% by mass of the aqueous dispersion to be produced.

  In particular, a polymer dispersant having a hydrophobic portion that exhibits sufficient water solubility and serves as an adsorption site for the surface of the colorant fine particles and the radically polymerizable monomer added in the polymerization process, particularly the hydrophobic monomer to the oil droplet interface. Is preferably used. More preferably, at least one of the hydrophobic monomers used in the subsequent polymerization step is present as a unit constituting the dispersing agent, so that the color of the charged resin pseudo fine particles in the subsequent polymerization step. This is preferable from the viewpoint of easily inducing adhesion to the material. The method for producing the polymer dispersant and water-soluble polymer that can be used in the present invention is not particularly limited. For example, among the above-described monomers constituting the resin component constituting the chargeable resin pseudo fine particles, the polymer dispersant has an ionic group. It can be produced by reacting a monomer with another polymerizable monomer in a non-reactive solvent in the presence or absence of a catalyst.

  In particular, a styrene / acrylic polymer compound obtained by polymerizing a monomer having an ionic group and a styrene monomer as essential components, or a monomer having an ionic group, It is clear that good results are obtained when a dispersant selected from ionic group-containing acrylic polymer compounds obtained by polymerizing acrylate monomer as an essential component is used. In this case, the purpose is that the dispersible colorant to be obtained has an anionic group especially when the objective is to have an anionic group, while the dispersible colorant to be obtained has a cationic group in particular. In this case, it is desirable to select a dispersant having a cationic group or a nonionic dispersant.

  From the viewpoint of both promoting the fixation of the chargeable resin pseudo fine particles to the coloring material in the process of the aqueous precipitation polymerization described above and maintaining the dispersion stability of the coloring material in the polymerization process. In the case of using a dispersant, it is also desirable to use an acid value of 100 to 250, and in the case of using a cationic polymer dispersant, an amine value of 150 to 300. When the acid value and the amine value are smaller than this range, the affinity between the hydrophobic monomer and the dispersant becomes too high during the aqueous precipitation polymerization, so that the charged resin pseudo fine particles are fixed to the colorant. In some cases, it is strongly adsorbed with the dispersant and is less likely to adhere to the colorant. Also, if the acid value and amine value are larger than this range, the excluded volume effect of the dispersant around the color material and the electrostatic repulsion force become too strong, so that the chargeable resin pseudo fine particles adhere to the color material. May be inhibited. When an anionic dispersant is used, it is preferable to select a dispersant having a carboxyl group as the anionic group from the viewpoint of not inhibiting the adhesion of the resin fine particles to the colorant.

  In the above-described step, particularly when the charged resin pseudo fine particles are obtained by polymerizing a monomer component containing at least one hydrophobic monomer and at least one hydrophilic monomer, the monomer component is preferably an aqueous radical. It is desirable to drop it into an aqueous dispersion of a water-insoluble colorant containing a polymerization initiator. In order to uniformly obtain desired self-dispersing resin fine particles from a mixture of monomers having different properties such as a hydrophobic monomer and a hydrophilic monomer, it is desirable to always keep the copolymerization ratio of the monomers having different properties constant. . When the mixture of monomers is added to the polymerization system in excess of the amount of monomer consumed in the polymerization reaction within a certain time, only a specific monomer species is polymerized in advance, and the remaining monomers are polymerized in advance. There is a tendency to polymerize after the consumed monomer is consumed, and in this case, a large non-uniformity occurs in the properties of the generated chargeable resin pseudo fine particles. Among the chargeable resin pseudo fine particles generated in this way, those having a particularly large hydrophilic monomer component content may not be able to adhere to the surface of the water-insoluble colorant. Furthermore, when the resin component has a high content of the hydrophilic monomer component, it may not be precipitated due to its high hydrophilicity, and may remain in the system as a water-soluble resin component without forming the chargeable resin pseudo fine particles. . On the other hand, by dropping the monomer component into an aqueous dispersion of a water-insoluble colorant containing an aqueous radical polymerization initiator, the copolymerization ratio of the hydrophobic monomer and the hydrophilic monomer is always kept constant, and is desired. The chargeable resin pseudo fine particles composed of the copolymerization ratio can be obtained uniformly.

  In addition, when adding an anionic monomer such as acrylic acid or methacrylic acid to the polymerization system as a hydrophilic monomer, depending on the characteristics of the water-insoluble colorant having a charge on the surface by binding polar groups May become unstable and cause aggregation. In order to prevent this, it is also a preferred embodiment that the anionic monomer is neutralized in advance and added in the form of sodium salt or potassium salt.

  When preparing an ink jet recording ink using the water-insoluble color material obtained by fixing or fusing the chargeable resin pseudo fine particles of the present invention obtained in the above-described process, in addition to the above-described process, a water-insoluble color is used. In order to remove resin fine particles that have not adhered to the surface of the material, monomers that have not reacted, impurities, and the like, further purification treatment may be performed. As a method for purification used at this time, an optimum method may be selected from generally used purification methods. For example, a method of purification using a centrifugal separation method or an ultrafiltration method may be mentioned as a preferred embodiment.

  Through the above-described steps, resin fine particles made of a desired copolymer can be formed on the surface of the water-insoluble colorant by controlling many control factors. In particular, when an anionic monomer is used for the purpose of high dispersion stability, the water-insoluble colorant having undergone the process of the present invention is highly dispersed even if the amount of the anionic monomer used in the above process is relatively small. Stability can be imparted. As a result, it is possible to increase the dispersion stability of the water-insoluble colorant without impairing water resistance. The reason for this is not clear, but according to the study by the present inventors, polymerization is initiated by radicals generated in water, and when an oligomer is precipitated to form a charged resin pseudo fine particle, Many portions are preferentially oriented near the water phase, that is, near the surface of the chargeable resin pseudo fine particles. This state is maintained even after the chargeable resin pseudo fine particles are fixed or fused to the water-insoluble colorant, and the surface of the water-insoluble colorant of the present invention having a structurally large specific surface area further comprises an anionic monomer component. As a result, it is expected that the water-insoluble colorant to which the chargeable resin pseudo fine particles are fixed or fused is stabilized with a smaller amount of anionic monomer component.

(6) Ink and ink set The water-based ink of the present invention includes the dispersible colorant described above. When the colorant is a pigment, the pigment content is generally 0.1% by mass or more and 20% by mass or less, and preferably 0.3% by mass or more and 15% by mass or less with respect to the ink.

  Next, components other than the aqueous dispersion constituting the ink in the present invention and the ink set will be described. The aqueous liquid medium used in the present invention preferably contains water as a main component, and the water content in the ink is 10 to 95% by mass, preferably 25 to 93% by mass with respect to the total mass of the ink. %, More preferably 40 to 90% by mass. As the water used in the present invention, ion-exchanged water is preferably used.

  In the ink of the present invention, water may be used alone as an aqueous liquid medium, but the effect of the present invention can be made more remarkable by using a water-soluble organic solvent in combination with water. Specific examples of the water-soluble organic solvent that can be used in the present invention include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, and isobutyl alcohol. Alkyl alcohols having 1 to 5 carbon atoms such as n-pentanol; amides such as dimethylformamide and dimethylacetamide; ketones or ketoalcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; Oxyethylene or oxypropylene such as triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, polypropylene glycol Lene addition polymers; alkylene glycols containing 2 to 6 carbon atoms such as ethylene glycol, propylene glycol, trimethylene glycol, butylene glycol, pentanediol, hexylene glycol; glycerin, trimethylolethane, trimethylol Triols such as propane and 1,2,6-hexanetriol; thiodiglycol; bishydroxyethyl sulfone; ethylene glycol monomethyl (or ethyl, butyl) ether, diethylene glycol monomethyl (or ethyl, butyl) ether, triethylene glycol monomethyl ( Or lower alkyl glycol ethers such as ethyl, butyl) ether; triethylene glycol dimethyl (or ethyl) ether, tetraethylene glycol dimethyl ether Lower dialkyl glycol ethers such as ru (or ethyl) ether; alkanolamines such as monoethanolamine, diethanolamine and triethanolamine; sulfolane, N-methyl-2-pyrrolidone, 2-pyrrolidone and 1,3-dimethyl-2 -Imidazolidinone and the like. The above water-soluble organic solvents can be used alone or as a mixture.

  The content of these water-soluble organic solvents in the ink is generally 50% by mass or less, preferably 5 to 40% by mass, more preferably 10 to 30% by mass with respect to the total mass of the ink. It is desirable to be in the range. Among these solvents, ethylene glycol, diethylene glycol, triethylene glycol, 2-pyrrolidone, glycerin, polyethylene glycol, 1,2,6-hexanetriol and the like are preferably used.

  In the ink of the present invention, in addition to the above components, if necessary, a surfactant, an antifoaming agent, a surface tension adjusting agent, a pH adjusting agent, a viscosity adjusting agent, and an antiseptic for imparting desired performance to the ink. Additives such as antioxidants, evaporation accelerators, rust inhibitors, fungicides, and chelating agents may be blended. As the surfactant, a nonionic surfactant may be added in order to adjust the surface tension and improve the discharge property. As the nonionic surfactant, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, ethylene oxide adduct of acetylene glycol and the like are preferable. HLB is preferably 10 or more, particularly 12 or more, and more preferably 15 or more. These surfactants are used in an amount of 0.3% by mass or more, particularly 0.5% by mass or more, and more preferably 0.8% by mass or more with respect to the total mass of the ink in order to obtain a sufficient discharge sustaining effect. If the amount is too large, the viscosity of the ink becomes too high. Therefore, it is preferably 3% by mass or less, particularly 2.5% by mass or less, more preferably 2.0% by mass or less, based on the total mass of the ink. .

  Furthermore, the chargeable resin pseudo fine particles (A) fixed or fused to the coloring material and the self-dispersible resin fine particles (B) dispersed and present in the ink may be present. When the monomer component constituting the chargeable resin pseudo fine particles (A) and the monomer component constituting the self-dispersing resin fine particles (B) comprise one or more types of common monomer components, the chargeable resin Since the affinity between the dispersible colorant to which the pseudo fine particles (A) are fixed and the self-dispersing resin fine particles (B) is increased and the adhesive force is increased, the scratch resistance of the printed matter particularly on the glossy medium is increased. The effect which improves is acquired.

  The viscosity of the ink of the present invention is preferably in the range of 0.7 to 12 mPa · s at 25 ° C. It is preferable that the viscosity of the ink is within the above-mentioned range because normal ejection can be performed in ink jet recording, and the penetration into the recording medium is quick due to the viscosity resistance, and there is no problem in terms of fixing properties. The surface tension of the ink used in the present invention is preferably adjusted to a range of 20 to 60 mN / m at 25 ° C. When the surface tension is 20 mN / m or more, after droplets are ejected in ink jet recording, the force to pull back the meniscus is strong. There is no problem of embracing or causing the orifice to get wet. By using the ink as described above, the ink proposed in the present invention is excellent in the water resistance of the obtained image, the ink storage stability, and the recording density, particularly as the ink used for plain paper compatible ink jet recording. In addition, it is possible to provide an ink excellent in performance of fixing property, printing quality, and fixing property.

  The water-based ink of the present invention configured as described above can be used as a stamp or pen ink, but is particularly effective when used in ink jet recording. Inkjet recording methods include a recording method in which mechanical energy is applied to ink to eject droplets, and an inkjet recording method in which thermal energy is applied to ink and droplets are ejected by foaming of the ink. The recording ink of the present invention is particularly suitable for the method.

  In the ink set of the present invention, at least one type of ink set having ink for black and color (including various possible colors such as yellow, magenta, cyan, red, blue, green, orange, and bio red) is used. The ink is the ink of the present invention. That is, an ink set in which all combinations of inks used are the inks of the present invention, or an ink that uses one ink (for example, black ink) as the ink of the present invention and another ink that uses a dye as a coloring material. A set is also included. These inks can be selected and combined as appropriate, and can be selected according to the purpose of use.

(7) Recorded image, image recording method and recording apparatus (recorded image)
The ink jet recording image of the present invention is formed on a recording medium using the water based ink of the present invention by an ink jet recording apparatus as will be described later. The recording medium in the present invention can be used without limitation even if it is an ink-jet recordable medium.

(Image recording method and recording apparatus)
The dispersible color material and the water-based ink of the present invention are used in an ink jet ejection type head, and are effective as an ink tank in which the ink is stored or as a filling ink. In particular, the present invention provides an excellent effect in a bubble jet type recording head and recording apparatus among ink jet recording types.

  As for the typical configuration and principle, for example, those performed using the basic principle disclosed in US Pat. Nos. 4,723,129 and 4,740,796 are preferable. . This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, the electric circuit arranged corresponding to the sheet or liquid path holding the ink is used. By applying at least one drive signal corresponding to the recording information and giving a rapid temperature rise exceeding nucleate boiling to the heat conversion body, heat energy is generated in the electrothermal conversion body, and the heat acting surface of the recording head This is effective because the film can be boiled and, as a result, the drive signals can be made to correspond one-to-one and bubbles in the ink can be formed. By the growth and contraction of the bubbles, ink is ejected through the ejection openings to form at least one droplet. It is more preferable that the drive signal has a pulse shape, because the bubble growth and contraction is performed immediately and appropriately, and thus ink discharge with particularly excellent responsiveness can be achieved. As this pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further excellent recording can be performed by employing the conditions described in US Pat. No. 4,313,124 of the invention relating to the temperature rise rate of the heat acting surface.

  As the configuration of the recording head, in addition to the combination configuration (linear liquid channel or right-angle liquid channel) of the discharge port, the liquid channel, and the electrothermal transducer as disclosed in each of the above-mentioned specifications, the heat acting part The present invention is also effective for configurations using US Pat. No. 4,558,333 and US Pat. No. 4,459,600, which disclose configurations in which the lens is disposed in a bending region. In addition, the present invention is also effective for a configuration (Japanese Patent Laid-Open No. 59-123670, etc.) in which a discharge hole is used as a discharge portion of the electrothermal transducer when common to a plurality of electrothermal transducers. .

  Furthermore, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length is set by combining a plurality of recording heads as disclosed in the above specification. Either a satisfying configuration or a single recording head configuration may be used, but the present invention can exhibit the above-described effects more effectively.

  In addition, it is mounted on the main body of the device so that it can be electrically connected to the main body of the device and supplied with ink from the main body of the device. The present invention is also effective when a cartridge type recording head is used. In the present invention, it is preferable to add recovery means for the recording head, preliminary auxiliary means, etc. provided as the configuration of the recording apparatus to be applied, because the effects of the present invention can be further stabilized. . Specifically, capping means for the recording head, cleaning means, pressurization or suction means, electrothermal converter or preheating means using a heating element different from these, or a combination thereof, and recording This is a preliminary discharge mode in which another discharge is performed.

Next, an Example and a comparative example are given and this invention is demonstrated concretely. The present invention is not limited by the following examples unless it exceeds the gist. In the text, “part” or “%” is based on mass unless otherwise specified.
[Examples 1 to 4]
Color materials 1 to 4 used as water-insoluble color materials in Examples and Comparative Examples are as follows. Using these coloring materials 1 to 4, the dispersible coloring material and the aqueous inkjet ink of Examples 1 to 4 of the present invention were produced.
Color material 1: C.I. I. Pigment Black (Cabot Jet 300: self-dispersing pigment / carboxylic acid group)
Color material 2: C.I. I. Pigment Blue 15: 3 (Cabot Jet 253: Self-dispersing pigment / sulfonic acid group)
Color material 3: C.I. I. Pigment Red 122 (Cabot Jet 266: Self-dispersing pigment / sulfonic acid group)
Color material 4: C.I. I. Pigment Yellow 74 (Cabojet, Cabojet 273: Self-dispersing pigment / sulfonic acid group)

Example 1
A recording ink 1 according to Example 1 was prepared in the following manner. First, in order to produce a black ink, water was added and adjusted so that the coloring material 1 was 10 parts in terms of solid content, whereby a pigment dispersion 1 was obtained. The obtained pigment dispersion 1 was stably dispersed with an average dispersion particle size of 97 nm, and the polydispersity index was 0.18. Next, with 100 parts of the pigment dispersion 1 heated to 70 ° C. under a nitrogen atmosphere, the following three liquids were respectively charged into a dropping device while being stirred with a motor, added dropwise, and polymerized for 5 hours. Went. The three solutions were (1) methyl methacrylate 5.5 parts, (2) acrylic acid 0.5 parts, potassium hydroxide 0.12 parts and water 20 parts, (3) potassium persulfate 0.05 parts and water. 20 parts. The obtained dispersion was diluted 10-fold with water and centrifuged at 5,000 rpm for 10 minutes to remove the aggregating component.

  At this time, the surface oxygen amount of the carbon black was measured for the coloring material 1 by the following method. The amount of surface oxygen of carbon black was measured by the following heat loss method. In this method, carbon black is heated for about 10 minutes at 950 ° C. under vacuum, and the amount of surface oxygen is estimated from the weight loss that occurs. That is, the gas generated by heating under the above conditions is carbon monoxide and carbon dioxide, and these gases are caused by carboxyl groups, hydroxyl groups, quinones, etc. present on the carbon surface. It can be said that the greater the weight loss, the greater the amount of surface oxygen. As a result of the measurement, the loss on heating was 10%.

  Then, the dispersible color material 1 which is a sediment was obtained by further centrifuging at 12,500 rpm for 2 hours. The dispersible colorant 1 is dispersed in water, centrifuged at 80,000 rpm for 90 minutes, and the precipitate is redispersed in water, dried, and scanned with a scanning electron microscope JSM-6700 (JEOL Hi-Tech). When the dispersible colorant 1 was observed at a magnification of 50,000, a state in which the resin pseudo fine particles were fixed to the surface of the carbon black was observed. Further, it was confirmed that the mass solid content of the supernatant obtained by centrifuging the dispersion under conditions of 80,000 revolutions and 90 minutes was within 1%, and the dispersible colorant 1 was smaller than the colorant. It was confirmed that the chargeable pseudo fine particles were fixed to the coloring material. In addition, the form is confirmed about the subsequent color material described in a present Example with the same method.

  In addition, the dispersible colorant prepared in the same manner is prepared separately, separated by a centrifuge at 12,000 rpm for 60 minutes, and after separation, the lower layer precipitate containing the colorant is removed. It was taken out and poured into toluene to dissolve it. Next, this was rotated 80,000 times in a centrifugal separator to precipitate and separate the water-insoluble colorant. Furthermore, when this coloring material was washed and then redispersed in pure water, it was dispersed without causing precipitation. In addition, it is confirmed whether the color material itself has a surface charge and is dispersible by the same method also about the color material after this described in a present Example. Further, the zeta potential was measured by the method shown in the following evaluation. The above results are shown in Table 1.

The following components were mixed so that the obtained dispersible colorant 1 had a concentration of 4% in the ink, and further filtered under pressure with a membrane filter having a pore size of 2.5 microns, and the recording of this example. Ink 1 was obtained. The total amount of ink was adjusted with water so as to be 100 parts. The same applies to the subsequent inks.
・ Glycerol 7 parts ・ Diethylene glycol 5 parts ・ Trimethylolpropane 7 parts ・ Acetylenol EH (trade name: manufactured by Kawaken Fine Chemicals Co., Ltd.) 0.2 part ・ Ion-exchanged water remaining

(Example 2)
A recording ink 2 according to Example 2 was produced in the following manner. First, in order to produce cyan ink, water was added and adjusted so that the coloring material 2 was 10 parts in terms of solid content, whereby a pigment dispersion 2 was obtained. The obtained pigment dispersion 2 was stably dispersed with an average dispersion particle size of 123 nm, and the polydispersity index was 0.20. Next, a dispersible colorant 2 was obtained in the same manner as in Example 1. In the obtained dispersible color material, observation and confirmation of adhesion of the chargeable pseudo fine particles to the color material and confirmation of dispersibility of the color material itself were performed in the same manner as in Example 1.

(Example 3)
A recording ink 3 according to Example 3 was prepared in the following manner. First, for the production of magenta ink, the coloring material 3 was adjusted by adding water so that the amount of the coloring material 3 was 10 parts in terms of solid content, whereby a pigment dispersion 3 was obtained. The obtained pigment dispersion 3 was stably dispersed with an average dispersion particle size of 127 nm, and the polydispersity index was 0.22. Next, a dispersible colorant 3 was obtained in the same manner as in Example 1. In the obtained dispersible color material, observation and confirmation of adhesion of the chargeable pseudo fine particles to the color material and confirmation of dispersibility of the color material itself were performed in the same manner as in Example 1.

Example 4
A recording ink 4 according to Example 4 was produced in the following manner. First, in order to produce a yellow ink, water was added and adjusted so that the coloring material 2 was 10 parts in terms of solid content, whereby a pigment dispersion 4 was obtained. The obtained pigment dispersion 4 was stably dispersed with an average dispersion particle size of 115 nm, and the polydispersity index was 0.17. Next, a dispersible colorant 4 was obtained in the same manner as in Example 1. In the obtained dispersible color material, observation and confirmation of adhesion of the chargeable pseudo fine particles to the color material and confirmation of dispersibility of the color material itself were performed in the same manner as in Example 1.

[Examples 5 to 10]
Using the color material of Example 1, a dispersible color material and an ink were prepared by changing the type, blending, and production conditions of the monomer mixture.

(Example 5)
Using 100 parts of the same pigment dispersion 1 prepared in Example 1 and heating to 70 ° C. in a nitrogen atmosphere, the following three liquids were filled in the dropping device while being stirred with a motor, and dropped. Then, polymerization was carried out for 8 hours. The three liquids were (1) 5.7 parts styrene, (2) 0.3 parts acrylic acid, 0.07 parts potassium hydroxide and 20 parts water, (3) 0.05 parts potassium persulfate and 20 parts water. Part. After the polymerization, purification was performed by centrifugation in the same manner as in Example 1 to obtain a dispersible colorant 5. Further, the recording ink 5 of this example was prepared in the same manner as in Example 1 so that the obtained dispersible colorant 5 had a concentration of 4%.

(Example 6)
Using 100 parts of the same pigment dispersion 1 prepared in Example 1 and heating to 70 ° C. in a nitrogen atmosphere, the following three liquids were filled in the dropping device while being stirred with a motor, and dropped. Then, polymerization was carried out for 6 hours. The three solutions are (1) 5.7 parts methyl methacrylate, (2) 0.3 parts acrylic acid, 0.07 parts potassium hydroxide and 20 parts water, (3) 0.05 parts potassium persulfate and 20 parts of water. After polymerization for 5 hours as described above, purification was performed by centrifugation in the same manner as in Example 1 to obtain dispersible colorant 6.

  Further, in the above, polymerization was carried out in the same manner using 100 parts of a 2% aqueous solution of the styrene-acrylic acid resin dispersant used in Example 1 instead of the pigment dispersion 1 and an equal amount of potassium hydroxide. In the same manner as in Example 1, purification was performed by centrifugation under the conditions of 20,000 rotations and 1 hour to obtain resin fine particles B1. The recording ink 6 of this example was prepared in the same manner as in Example 1 so that the obtained dispersible colorant 6 was 4% concentration and the resin fine particle B1 was 1.2% concentration.

(Example 7)
Using 100 parts of the same pigment dispersion 1 prepared in Example 1 and heating to 70 ° C. in a nitrogen atmosphere, the following three liquids were filled in the dropping device while being stirred with a motor, and dropped. Then, polymerization was carried out for 6 hours. The three solutions were (1) 4.5 parts benzyl methacrylate and 1.2 parts butyl acrylate, (2) 0.3 parts acrylic acid, 0.07 parts potassium hydroxide and 20 parts water, (3) It consists of 0.05 part of potassium persulfate and 20 parts of water. After the polymerization, purification was performed by centrifugation in the same manner as in Example 1 to obtain a dispersible colorant 7.

  Furthermore, in the above, the same replacement as in Example 6 was performed, and purification by polymerization and centrifugation was performed to obtain resin fine particles B2. When observation was performed in the same manner as in Example 1, it was observed that the resin pseudo fine particles were fixed to the surface of the carbon black even in the dispersible colorant 7. In the case of Example 1, It was confirmed that there were many fused parts compared to. The recording ink 7 of this example was prepared in the same manner as in Example 1 so that the obtained dispersible colorant 7 was 4% concentration and the resin fine particle B2 was 1.2% concentration.

(Example 8)
Using 100 parts of the same pigment dispersion 1 prepared in Example 1 and heating to 70 ° C. in a nitrogen atmosphere, the following three liquids were filled in the dropping device while being stirred with a motor, and dropped. In addition, polymerization was carried out for 5 hours. The three solutions were (1) 17.2 parts methyl methacrylate, (2) 0.8 parts sodium p-styrenesulfonate and 20 parts water, (3) 0.05 parts potassium persulfate and 20 parts water, Consists of. After polymerization for 7 hours as described above, purification was performed by centrifugation in the same manner as in Example 1 to obtain dispersible colorant 8. A recording ink 8 of this example was prepared in the same manner as in Example 1 so that the obtained dispersible colorant 8 had a concentration of 4%.

Example 9
Using 100 parts of the same pigment dispersion 1 prepared in Example 1 and heating to 70 ° C. in a nitrogen atmosphere, the following three liquids were filled in the dropping device while being stirred with a motor, and dropped. In addition, polymerization was carried out for 5 hours. The three liquids were: (1) 4.0 parts of butyl acrylate and 1.5 parts of methoxypolyethylene glycol monomethacrylate (molecular weight about 1,100, manufactured by Shin-Nakamura Chemical Co., Ltd., trade name M230G), (2) acrylic It consists of 0.5 part of acid, 0.35 part of potassium hydroxide and 20 parts of water, (3) 0.05 part of potassium persulfate and 20 parts of water. After polymerization for 5 hours as described above, purification was performed by centrifugation in the same manner as in Example 1 to obtain dispersible colorant 9. Observation was made in the same manner as in Example 1, and in the dispersible colorant 9, flat spherical charged resin pseudo fine particles in which the resin pseudo fine particles were smaller than carbon black were fused to the surface of carbon black. I was able to confirm the status. A recording ink 9 of this example was prepared in the same manner as in Example 1 so that the obtained dispersible colorant 9 had a concentration of 4%.

(Example 10)
Using 100 parts of the same pigment dispersion 1 prepared in Example 1 and heating to 70 ° C. in a nitrogen atmosphere, the following three liquids were filled in the dropping device while being stirred with a motor, and dropped. Then, polymerization was carried out for 8 hours. The three liquids were (1) 3.0 parts of benzyl methacrylate and 2.5 parts of methoxypolyethylene glycol monomethacrylate (molecular weight of about 500, manufactured by Shin-Nakamura Chemical Co., Ltd., trade name M230G), (2) acrylic acid 0 5 parts, 0.35 parts of potassium hydroxide and 20 parts of water, (3) 0.05 part of potassium persulfate and 20 parts of water. After the polymerization, purification was performed by centrifugation in the same manner as in Example 1 to obtain a dispersible colorant 10. Further, the recording ink 10 of this example was prepared in the same manner as in Example 1 so that the obtained dispersible colorant 10 had a concentration of 4%.

(Comparative Example 1)
A recording ink according to Comparative Example 1 was prepared as follows. That is, an ink using a conventional self-dispersing pigment was prepared. The same pigment dispersion used in Example 1 was used, and this pigment dispersion was used so that the pigment concentration would be 4% without subjecting the pigment dispersion to polymerization treatment. A recording ink of this comparative example was prepared in the same manner.

(Comparative Example 2)
A recording ink according to Comparative Example 2 was prepared as follows. That is, it was prepared using a pigment dispersed with a conventional polymer resin dispersion. First, a mixed liquid composed of 10 parts of carbon black (Black Pearls 880 manufactured by Cabot, USA), 6 parts of glycerin, 10 parts of styrene-acrylic acid resin dispersant, and 74 parts of water was placed in a sand mill manufactured by Kanada Rika Kogyo Co., Ltd. And dispersed at 1,500 rpm for 5 hours to obtain a pigment dispersion 12. At this time, the surface oxygen amount of carbon black was measured by the following heating loss method. In this method, carbon black is heated for about 10 minutes at 950 ° C. under vacuum, and the amount of surface oxygen is estimated from the weight loss that occurs. That is, the gas generated by heating under the above conditions is carbon monoxide and carbon dioxide, and these gases are caused by carboxyl groups, hydroxyl groups, quinones, etc. present on the carbon surface. It can be said that the greater the weight loss, the greater the amount of surface oxygen. As a result of the measurement, the heat loss was 1.5%. When dispersing with a sand mill, zirconia beads having a diameter of 0.6 mm were used, and the filling rate in the pot was 70%. Here, a styrene-acrylic acid resin dispersant having a copolymerization ratio of 70:30, Mw = 8,000, and an acid value of 170 was used. As the styrene-acrylic acid resin dispersant, water and potassium hydroxide equivalent to the above acid value were added in advance and stirred at 80 ° C. to obtain an aqueous solution. The obtained pigment dispersion was stably dispersed with an average dispersion particle size of 98 nm, and the polydispersity index was 0.16. Next, a recording ink of this comparative example was prepared in the same manner as in Example 1 using this pigment dispersion so that the pigment concentration would be 4%.

(Comparative Example 3)
A recording ink according to Comparative Example 3 was prepared in the following manner, that is, by a microcapsule method using a conventional phase inversion emulsification method. First, a mixed solution comprising 175 parts of n-butyl methacrylate, 10.5 parts of n-butyl acrylate, 37.5 parts of β-hydroxyethyl methacrylate, 26.8 parts of methacrylic acid and 20 parts of t-butyl peroxyoctoate was prepared. Further, the mixture was heated to 250 ° C. with stirring in 250 parts of methyl ethyl ketone under a nitrogen atmosphere, the above mixed solution was dropped over 2 hours, and further reacted for 15 hours while maintaining the temperature to prepare a resin solution. Next, 11.6 parts of this resin solution, 1.6 parts of diethanolamine and 30 parts of carbon black (Black Pearls 880 manufactured by Cabot, USA) are added, and the total amount is 150 parts, and 500 g of zirconia beads having an average particle diameter of 0.5 mm are added. It knead | mixed for 4 hours with the paint shaker. Finally, zirconia beads were separated by filtration to obtain a dispersion composed of a resin and a pigment.

  Next, pure water was further added, diluted 1-fold, and 1N hydrochloric acid was added while stirring, and dropped until the color material was covered with the resin. In addition, pH at this time was 3-5. Subsequently, suction filtration was performed, and the salt was washed with water to obtain a water-containing cake. A 10% aqueous solution of diethanolamine was added so that the pH was 8.5 to 9.5. Further, after stirring for 1 hour, the pigment dispersion was adjusted so that the colorant concentration became 10%. The obtained pigment dispersion was stably dispersed with an average dispersion particle size of 98 nm, and the polydispersity index was 0.16. Next, using this pigment dispersion, a recording ink 13 of this comparative example was prepared in the same manner as in Example 1 so that the pigment concentration was 4%.

(Comparative Example 4)
A recording ink according to Comparative Example 4 was prepared in the following manner, that is, a mixed ink of a conventional self-dispersed pigment and a pigment prepared by a microcapsule method using a conventional phase inversion emulsification method. Using the pigment dispersion prepared in Comparative Example 1 and the pigment dispersion prepared in Comparative Example 3, these pigment concentrations are each 2%, that is, the total pigment concentration is 4%. Thus, a recording ink of this comparative example was prepared in the same manner as in Example 1.

(Comparative Example 5)
A recording ink according to Comparative Example 5 was prepared in the following manner, that is, a pigment ink prepared by coating a conventional self-dispersed pigment by a microcapsule method using a conventional phase inversion emulsification method. First, the pigment dispersion liquid 1 of Example 1 was dried in a 90 ° C. oven to obtain a powder. Next, a mixed solution consisting of 175 parts of n-butyl methacrylate, 10.5 parts of n-butyl acrylate, 37.5 parts of β-hydroxyethyl methacrylate, 26.8 parts of methacrylic acid and 20 parts of t-butyl peroxyoctoate was prepared. Then, the mixture was heated to 75 ° C. with stirring in 250 parts of methyl ethyl ketone under a nitrogen atmosphere, the above mixed solution was dropped over 2 hours, and further reacted for 15 hours while maintaining the temperature to prepare a resin solution. Next, 11.6 parts of this resin solution, 1.6 parts of diethanolamine, and 30 parts of carbon black pigment obtained by drying were added, and a total amount of 150 parts of zirconia beads having an average particle diameter of 0.5 mm was added, and paint was added. It knead | mixed for 4 hours with the shaker. Finally, zirconia beads were separated by filtration to obtain a dispersion composed of a resin and a pigment.

  Next, pure water was further added, diluted 1-fold, and 1N hydrochloric acid was added while stirring, and dropped until the color material was covered with the resin. In addition, pH at this time was 3-5. Subsequently, suction filtration was performed, and the salt was washed with water to obtain a water-containing cake. A 10% aqueous solution of diethanolamine was added so that the pH was 8.5 to 9.5. Further, after stirring for 1 hour, the pigment dispersion was adjusted so that the colorant concentration became 10%. The obtained pigment dispersion was stably dispersed with an average dispersion particle size of 98 nm, and the polydispersity index was 0.16. Next, a recording ink of this comparative example was prepared in the same manner as in Example 1 using this pigment dispersion so that the pigment concentration was 4%.

[Evaluation]
(Dispersible colorant characteristics)
Each of the dispersible color materials obtained in Examples 1 to 10 and Comparative Examples 1 to 5 or the color material constituting the pigment dispersion (hereinafter referred to as dispersible color material) is observed by the methods described below, and various color materials are used. Table 1 to Table 3 show the obtained results.

<Observation results / spotting>
Each dispersible colorant is dispersed in water and dried, and is observed with a scanning electron microscope JSM-6700 (manufactured by JEOL Hi-Tech Co., Ltd.) at a magnification of 50,000, and resin fine particles are fixed or fused. The case where the state could be confirmed was evaluated as ○, and the case where the state was not confirmed was evaluated as ×. In addition, during observation, evaluation was made with ◯ indicating that the resin fine particles were scattered, and X indicating localized or non-uniform fusion. did. Furthermore, the state of fixation and fusion was confirmed.

<Dispersion stability>
A 5% aqueous dispersion of each dispersible colorant is diluted 10-fold with pure water, concentrated to the original concentration using an ultrafiltration filter with a molecular weight cut off of 50,000, and the concentrated solution is centrifuged. At 12,000 rpm for 2 hours. The separated sediment is taken out and redispersed in pure water, and is visually dispersed uniformly. The average particle diameter measured by the dynamic light scattering method described later is 2 before the operation. It was confirmed that the dispersion was within the range, and the single dispersibility was evaluated by ◯ indicating that the condition was satisfied and × indicating that the condition was not satisfied.

<Confirmation of presence or absence of charge on color material surface, measurement of zeta potential>
Each dispersible colorant is dispersed in water and separated in a centrifuge at 12,000 rpm for 60 minutes. After separation, the lower layer precipitate containing the colorant is taken out and put in toluene. And dissolved. Next, this was rotated 80,000 times in a centrifugal separator to precipitate and separate the water-insoluble colorant. Furthermore, this coloring material was washed and then redispersed in pure water to confirm the presence of precipitates. If there is no precipitate, the mark is ○, and if there is no precipitate, each dispersible colorant is diluted with pure water to about 100,000 times, and the cell is stopped with ZEECOM manufactured by Microtech Nichion. The value of the ζ potential on the surface was measured for 100 particles, and the average value was taken as the ζ potential of each color material. Furthermore, the standard deviation of each value measured for 100 was obtained.

<Average dispersed particle size>
Each dispersible colorant was measured by a dynamic light scattering method using ELS-8000 manufactured by Otsuka Electronics Co., Ltd., and the cumulant average value was defined as the average particle size.

<Glass transition temperature: Tg (° C.)>
The glass transition temperature of the resin fine particles adhering to each dispersible colorant was measured with a DSC822e manufactured by METTLER TOLEDO using a sample obtained by drying the dispersible colorant.

<Surface functional group density>
The surface functional group density of each dispersible colorant was determined as follows. A large excess of HCl aqueous solution is added to the aqueous dispersion of the color material, and the precipitate precipitated at 20,000 rpm for 1 hour in a centrifugal separator is redispersed in pure water, and the solid content is determined to obtain the precipitate. The dispersion obtained by weighing, adding a known amount of sodium hydrogen carbonate and stirring the mixture was further precipitated in a centrifuge at 80,000 rpm for 2 hours. The supernatant was weighed, and the surface functional group density was calculated by subtracting the blank value obtained by measuring the known amount of sodium bicarbonate and pure water from the neutralization amount obtained by neutralization titration with 0.1 N HCl. When it was clear that it had a cationic group as a polar group, NaOH was used instead of HCl and ammonium chloride was used instead of sodium bicarbonate in the same manner.

(Evaluation method and evaluation result of recording ink)
Each recording ink obtained by the above-described method was used to print on a recording medium with an ink jet recording apparatus, and the obtained image was evaluated. As an ink jet recording apparatus used, an image was formed using an ink jet printer BJS700 manufactured by Canon Inc. At this time, black ink was injected into the BCI-3eBk tank, and cyan, magenta, and yellow were injected into the tanks of the respective colors and set. Then, the optical density (OD), scratch resistance, marker resistance and ejection stability of the printed matter printed under the above conditions are evaluated as follows, and further, the long-term storage stability of the ink itself is confirmed. The results are shown in Tables 4-6.

<Optical density (OD)>
After printing Bk text on Canon PPC paper using each recording ink, the optical density (OD) of the printed matter after one day was measured. The case where the OD of the printed matter was 1.4 or more was evaluated as A, the case where the OD was 0.8 or more and less than 1.4 was evaluated as B, and the case where the OD was less than 0.8 was evaluated as C. However, in Examples 2, 3, and 4, instead of Bk text, cyan, magenta, and yellow texts are printed, the optical density in each color is measured, and the case where OD is 1.0 or more is designated as A. evaluated.

<Abrasion resistance>
The scratch resistance of the printed matter was evaluated based on the following criteria by rubbing the printed portion with a Silbon paper having a weight of 40 g / cm ² 5 times, visually observing the disorder of the printed portion.
A: There is no disorder of printing due to rubbing or smearing of the white part.
B: There is almost no disorder of printing due to rubbing and no smearing of the white part, and it is not worrisome.
C: Printing is greatly disturbed by rubbing, and white portions are stained.

<Marker resistance>
The marker resistance of the printed matter was evaluated based on the following criteria by tracing the printed portion once with a fluorescent yellow marker pen (Zebra Optix) and visually observing the disorder of the printed portion.
A: The printed part is not disturbed.
B: There is little disorder of printing in the traced part, and the pen tip is hardly soiled.
C: The trace of the traced part is greatly disturbed, and the pen tip is colored.

  As shown in the table, the observation results were good in any of the examples, and it was confirmed that a color material having good dispersion stability was obtained. In addition, any of the recording inks showed excellent printing performance.

[Example 11 to Example 12]
Using the color material of Example 1, a dispersible color material was produced by changing the production conditions without changing the type and composition of the monomer mixture.

(Example 11)
Using 100 parts of the same pigment dispersion 1 prepared in Example 1, heated to 70 ° C. in a nitrogen atmosphere, the following mixture was gradually added dropwise with stirring by a motor, and polymerization was performed for 8 hours. went. The mixed solution was 5.5 parts of methyl methacrylate, 0.5 part of acrylic acid, 0.12 part of potassium hydroxide, 0.05 part of potassium persulfate, styrene-acrylic acid resin dispersant (copolymerization ratio 70: 30, Mw = 8,000, acid value 170) 0.2 part and water 20 part. The styrene-acrylic acid resin dispersant used in this example was prepared by adding water and potassium hydroxide equivalent to the above acid value in advance and stirring at 80 ° C. to obtain a 20% aqueous solution. . The obtained dispersion was diluted 10-fold with water and centrifuged at 5,000 rpm for 10 minutes to remove the aggregating component. Then, the dispersible color material 11 which is a sediment was obtained by further centrifuging at 12,500 rpm for 2 hours. A recording ink 11 of this example was prepared in the same manner as in Example 1 so that the obtained dispersible colorant 11 had a concentration of 4%.

(Example 12)
Using 100 parts of the same pigment dispersion 1 prepared in Example 1, heated to 70 ° C. in a nitrogen atmosphere, the following mixture was gradually added dropwise with stirring by a motor, and polymerization was performed for 8 hours. went. The mixed solution was 5.5 parts of methyl methacrylate, 0.5 part of acrylic acid, 0.12 part of potassium hydroxide, 0.05 part of potassium persulfate, styrene-acrylic acid resin dispersant (copolymerization ratio 25: 75, Mw = 6,000, acid value 420) 0.2 part and water 20 part. The styrene-acrylic acid resin dispersant used in this example was prepared by adding water and potassium hydroxide equivalent to the above acid value in advance and stirring at 80 ° C. to obtain a 20% aqueous solution. . The obtained dispersion was diluted 10-fold with water and centrifuged at 5,000 rpm for 10 minutes to remove the aggregating component. Then, the dispersible color material 12 which is a sediment was obtained by further centrifuging at 12,500 rpm for 2 hours. A recording ink 12 of this example was prepared in the same manner as in Example 1 so that the obtained dispersible colorant 12 had a concentration of 4%.

[Evaluation]
(Resin dispersible colorant mass / pigment mass ratio)
For each dispersible colorant obtained in Examples 1, 11 and 12, the ratio of resin mass / pigment mass (B / P) was measured. The sediments centrifuged at 80,000 rpm for 2 hours were dried, weighed, and each of the pigment and the resin component when heated in the atmosphere using TGA / SDTA851 manufactured by METTTLER. The mass change before and after the decomposition temperature was determined, and B / P was calculated.

(Evaluation method and evaluation result of recording ink)
Printing was performed in the same manner as in Examples 1 to 10 and Comparative Examples 1 to 5, and scratch resistance was evaluated. The results are shown in Table 7. All showed good scratch resistance, but it was visually confirmed that Example 11 having a particularly large B / P ratio showed particularly excellent scratch resistance.

(Example 13)
A recording ink 16 was produced in the following manner using the color material 5 having a surface charge having a polarity different from that of Example 1. First, H of water ^{_{30g 3 N + C 6 H 4}} N + (CH 3) 3 Cl - · I - is in a solution dissolved 3.08 g, added with stirring silver nitrate 1.69 g. The generated precipitate is removed by filtration, and the filtrate is added to a suspension in which 10 g of carbon black having a specific surface area of 230 m ² / g and DBPA of 70 ml / 100 g is dispersed in 70 g of water. Next, 2.25 g of concentrated nitric acid is added, and then a solution of 0.83 g of sodium nitrite dissolved in 10 g of water is added. Then, a diazonium salt having an N ₂ ⁺ C ₆ H ₄ N ⁺ (CH ₃ ) ₃ group having the structure shown below reacts with carbon black to generate nitrogen gas. When nitrogen gas bubbles stop, the dispersion is dried in an oven at 120 ° C. As a result, a product having C ₆ H ₄ N ⁺ (CH ₃ ) ₃ groups on the surface of carbon black was obtained. The obtained carbon black powder was redispersed in water to obtain a self-dispersing carbon black dispersion having a pigment concentration of 15%. The obtained carbon black counter ion was converted to a conjugate base of acetic acid with an ion exchange resin to obtain a carbon black dispersion (coloring material 5), and then water was added so that it became 10 parts in terms of solid content Thus, a pigment dispersion liquid 16 was obtained. The obtained pigment dispersion liquid 16 was stably dispersed with an average particle diameter of 105 nm, and the polydispersity index was 0.19.

  Next, 100 parts of the pigment dispersion 16 was heated to 55 ° C. in a nitrogen atmosphere, and a liquid mixture having the following composition was gradually added dropwise while stirring with a motor, and polymerization was performed for 7 hours. The mixture consists of 4.2 parts of benzyl methacrylate, 1.8 parts of dimethylaminoethyl acrylate, 0.3 part of potassium persulfate, equimolar amount of sodium thiosulfate and 20 parts of water. After the polymerization, the obtained dispersion was diluted 10 times with water, and centrifuged at 5,000 rpm for 10 minutes to remove the aggregating component, thereby obtaining a dispersible colorant 16.

  Observation and confirmation of fixation of the obtained chargeable pseudo fine particles of the dispersible color material and confirmation of dispersibility of the color material itself were carried out in the same manner as in Example 1. Further, an ink was prepared in the same manner as in Example 1. Next, observation and various physical properties were measured in the same manner as in Example 1, and the obtained results are shown in Table 8. Further, printing was performed using the recording ink in the same manner as in Example 1, and the same evaluation was made. The results are shown in Table 9.

  According to the present invention, adhesion is improved by a method of adhering and fixing a resin to a water-insoluble coloring material, that is, by improving the adhesion and fixing state and shape of the adhering and fixing resin to the surface characteristics of the water-insoluble coloring material. By controlling the fixed arrangement state, processing that makes use of the characteristics of the resin that adheres and fixes to the surface of the colorant and the surface of the water-insoluble colorant can be performed. Therefore, it is possible to provide a dispersible color material having a sufficiently high dispersion stability and a simple production method using a color material that is essentially insoluble in water. Furthermore, using the dispersible colorant, not only can it be stably dispersed in the ink, but the resulting printed matter has both excellent image quality (image density), excellent scratch resistance, and marker resistance. It became possible to provide an aqueous inkjet recording ink.

It is a schematic diagram which shows the basic structure of the dispersible color material which has fixed or fused the chargeable resin pseudo fine particles according to the present invention. It is a schematic diagram of the typical process in the manufacturing method of this invention. It is a schematic diagram which shows the process of the refinement | purification of the chargeable resin pseudo fine particles and the adhering to a color material, or a fusion | melting in the manufacturing method of this invention. It is the schematic diagram which expanded the chargeable resin pseudo fine particle of this invention from the interface side fixed or melt | fused with a coloring material. It is the schematic diagram which expanded the interface where the chargeable resin pseudo fine particles of the present invention and the coloring material are fixed or fused. It is a schematic diagram of a pigment peeling phenomenon when a hydrophilic group is directly modified on a conventional organic pigment.

Explanation of symbols

1: Color material 2-1: Charged resin pseudo fine particles 2-2: Partially fused charge resin pseudo fine particles 2-3: Fused flat chargeable resin pseudo fine particles 3: Dispersant 4: Monomer 5: Polymerization initiator aqueous solution 6: Dispersible colorant 7: Oligomer formed by polymerization of monomer 8: Precipitate in which oligomer is insolubilized in water 9-1: Hydrophilic monomer unit portion 9-2 in charged resin pseudo fine particles : Hydrophobic monomer unit portion 10 in the chargeable resin pseudo fine particles 10: Bonding site with the color material 11: Interface portion with the color material of the charge resin pseudo fine particle 12: Hydrophilic group directly modified on the color material

Claims (22)

  A dispersible color material in which a color material and a chargeable resin pseudo fine particle smaller than the color material are fixed or fused, and the color material itself has a surface charge.   The dispersible color material according to claim 1, wherein a plurality of the chargeable resin pseudo fine particles are scattered and fixed to the color material.   The dispersible color material according to claim 1, wherein flat colored resin fine particles are scattered and fused to the color material.   The surface charge of the color material itself is measured by a surface zeta potential in pure water, an average value thereof is -100 mV or more and -15 mV or less, and its distribution is less than 50 in standard deviation. The dispersible color material according to any one of the above items.   The surface charge of the coloring material itself is measured by a surface zeta potential in pure water, the average value is +10 mV or more and +70 mV or less, and the distribution is less than 50 in standard deviation. The dispersible colorant according to item 1.   The dispersible color material according to any one of claims 1 to 5, wherein a polar group is bonded to the surface of the color material itself.   The dispersible colorant according to claim 6, wherein the polar group bonded to the surface of the colorant itself is an anionic group or a cationic group.   The dispersible colorant according to any one of claims 1 to 7, wherein a polar group having the same polarity as the chargeable pseudo fine particles is chemically bonded to the surface of the colorant itself.   The dispersible colorant according to any one of claims 1 to 8, wherein the dispersible colorant has a surface functional group density of 250 µmol / g or more and less than 1,000 µmol / g.   The dispersible colorant according to any one of claims 1 to 9, wherein a loss on heating of the colorant is 2% by mass or more and 20% by mass or less.   The dispersion according to any one of claims 1 to 10, wherein the chargeable pseudo fine particles comprise a copolymer of monomer components including at least one kind of hydrophobic monomer and at least one kind of hydrophilic monomer. Sex color material.   In an aqueous dispersion of a water-insoluble colorant in which at least one polar group is bonded to the surface directly or via another atomic group, the radical polymerizable monomer is dissolved in an aqueous system using an aqueous radical polymerization initiator. A method for producing a dispersible colorant, characterized by forming a chargeable resin pseudo fine particle that is precipitated and polymerized to adhere or fuse to the surface of the water-insoluble colorant.   The method for producing a dispersible colorant according to claim 12, wherein the radical polymerizable monomer includes at least one kind of hydrophobic monomer and at least one kind of hydrophilic monomer.   The method for producing a dispersible colorant according to claim 12 or 13, wherein the water-soluble polymer is polymerized before or during the process of aqueous precipitation polymerization of the radical polymerizable monomer using the aqueous radical polymerization initiator. A method for producing a dispersible colorant, characterized by being added inside.   The method for producing a dispersible colorant according to claim 14, wherein the water-soluble polymer comprises at least a polymer dispersant having an acid value of 100 to 250 or an amine value of 150 to 300. .   A dispersible colorant produced by the production method according to any one of claims 12 to 15.   A water-based ink comprising the dispersible colorant according to any one of claims 1 to 11 and 16.   The color material constituting the dispersible color material is a pigment, and the ratio of the pigment to the total resin components contained in the ink (resin mass / pigment mass = B / P) is 0.1 or more and 4. The water-based ink according to claim 16 or 17, which is in a range of 0 or less.   An ink tank comprising the water-based ink according to claim 17 or 18.   An ink jet recording apparatus comprising the water-based ink according to claim 16.   An ink jet recording method comprising forming an image with an ink jet recording apparatus using the water-based ink according to claim 16. An inkjet recording image formed by an inkjet recording apparatus using the water-based ink according to claim 16 or 18.

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