RU2318849C2 - Dispergated coloring agent and the method of its production, the water ink, the container for the ink, the ink-jet inscriber, the method of the ink-jet recording and the ink-jet recorded images produced at its application - Google Patents

Abstract

FIELD: nonferrous metallurgy industry; aircraft industry; other industries; production of the heat-resistant alloys on the basis of the nickel.

SUBSTANCE: the invention is pertaining to the dispergated coloring agents intended for the ink-jet recording. The invention describes the dispergated coloring agent containing the coloring agent and the pseudo-finely-dispergated particles of the polarizable polymer having the dimension less, than the particles of the coloring agent. In the dispergated coloring agent the coloring agent itself and the particles of the polarizable polymer are attached to each other. At that the pseudo-finely-dispergated particles of the polarizable polymer contain the interpolymer consisting of the monomeric components containing, at least, one type of the hydrophobic monomer and, at least, one type of the hydrophilic monomer, where the hydrophobic monomer contains, at least, the monomer having the methyl group in α - position and the radically-polymerizable non-saturated double bond. The invention also describes the method of production of the indicated dispergated coloring agent and the water ink produced on its basis. The presented dispergated coloring agent has the high stability for a long time and practically in the absence of the surface-active substance or the dispergator. The ink produced on its basis has stability of blowout in the ink-jet printing method.

EFFECT: the invention ensures, that the ink produced on the basis of the presented dispergated coloring agent has the high stability of blowout in the ink-jet printing method.

20 cl, 14 dwg, 7 tbl, 15 ex

Description

FIELD OF THE INVENTION

The present invention relates to a dispersible colorant and a method for its production, aqueous inkjet ink, an inkjet recording device, an inkjet recording method and images recorded by inkjet recording obtained by its use.

State of the art

In inkjet recording, various operating principles are applied to obtain images, letters or the like by dropping small droplets of ink from nozzles onto a recording medium (substrate) (paper or similar material). Inkjet recording has gained rapid spread in various fields due to its advantages, for example: high speed, low noise, ease of obtaining multi-color images, high flexibility of recorded samples and the absence of the need for manifestation / fixing. In particular, in recent years, significant progress has been made in full-color inkjet printing techniques using water-based ink, and it is now possible to obtain multi-color images that are no worse than those obtained by conventional printing or photography methods. Such techniques have become widespread in the field of full-color printing of images, since they allow you to obtain images at a lower cost than conventional printing methods or photographs, if the number of copies is limited.

The inkjet recording apparatus and the recording method using water inks have been improved to meet the requirements of improved printing characteristics such as higher speed, sharper images and full color images. In general, inkjet ink for an inkjet recording device must satisfy the following characteristics: (1) images must have a higher resolution and density, should not contain smudges or clouding, (2) ink should be ejected without drying at the edges of the nozzle to prevent clogging, while while maintaining good ejection and stability characteristics, (3) the ink should be well fixed on paper, (4) the images should be resistant (i.e. resistant to weather, water or similar phenomena) and (5) the image must be sustainable for a long time. Due to the recent increase in printing speed, inks are especially in demand, which quickly dry and fix, and also provide high print quality even on ordinary printing paper, such as copy paper.

Water-based inkjet dyes are made up primarily of ink or pigment. Water-soluble dyes are mainly used, as they are easy to handle and exhibit good color. Recently, however, water-insoluble paints, in particular pigments, which can provide higher resistance of the image obtained by ink-jet recording to weather and water, have been widely used for water inks. If a water-insoluble dye, in particular a pigment, is used in aqueous ink for inkjet recording, it must be stably dispersible in water. The high stability of the dispersion of water-insoluble dyes is mainly achieved by adding a surfactant or polymer dispersant (hereinafter referred to as "dispersing resin"). Other methods for producing a stable dispersion of water-insoluble dyes include chemical modification of their surfaces (for example, Japanese Patent Application Laid-Open No. H10-195360). On the other hand, a microcapsule-based pigment has been proposed, for example, a pigment with a resin coating (for example, Japanese Patent Application Laid-open No. H8-183920 and 2000-34770). Japanese Patent Application Laid-Open No. 2003-34770 describes a “water dispersion of finely dispersed colored particles that polymerizes in the presence of a vinyl monomer after a water-insoluble colorant is introduced into it, dispersed in an aqueous medium using a dispersant, where this dispersion is stable, when the dispersant helps disperse a water-insoluble colorant, and when the vinyl monomer polymerizes only in the presence of a dispersant, the resulting latex is not stable ", and described that “a dispersion of a water-insoluble dye can be obtained by polymerizing the emulsion in high yield in the absence of agglomeration of finely dispersed pigment particles in the shell, since the affinity of the dispersant to the vinyl monomer and its polymer is not so high, so that a limited separation from the surface of the pigment particles is obtained, and polymerization takes place on the surfaces of the pigment particles adsorbed by the dispersant. " The inventors of the present invention provide inkjet ink that has excellent dispersion and printing stability characteristics, gives a slight metallic sheen, and excellent water, light and scratch resistance regardless of paper type.

SUMMARY OF THE INVENTION

These techniques, however, do not always simultaneously and sufficiently satisfy the characteristics of dispersion stability and storage stability over long periods of time. The authors of this invention believe that in order to be stably dispersible in ink, the dye must have a high density functional group on the surface. When using conventional methods that use a polymer dispersant, and the methods described in Japanese Patent Application Laid-Open No. H8-183920, which uses a pigment with a polymer coating, increasing the acid number of the polymer to improve dispersion stability sometimes cannot provide sufficient stability when storage for a long time, since it is accompanied by increased hydrophilicity of the polymer and tends to lead to desorption of the polymer from the dye over time. On the other hand, surface modification of a water-insoluble colorant by chemical methods described in Japanese Patent Application Laid-Open No. H10-195360 also faces problems. For example, modifiable functional groups and their density are limited. Direct chemical modification, in particular, if the dye is an organic pigment, can bind the hydrophilic group 12 to the pigment molecules, which are initially insoluble in water and have a crystalline form, turning them into hydrophilic pigment molecules 13, which are separated from the molecules of the original pigment, significantly changing color , this phenomenon is called color stratification (Figs. 6A and 6B). Therefore, such conventional techniques are not developed to the extent that meets modern requirements.

The aim of this invention is a dispersible dye having a sufficiently high dispersion stability, in which there is no separation of the polymer component from the dye, and which is stable over a long period of time, which solves the problems characteristic of conventional methods. Another objective of the present invention is a method for easily obtaining the specified dye. Other objects of the present invention are aqueous inks comprising an excellent dispersible inkjet colorant, an ink tank, an inkjet recording apparatus, an inkjet recording method and an inkjet recording image.

The authors of this invention have developed, after a comprehensive study of ways to solve the above problems, a new dispersible dye having a new shape, which can maintain high dispersion stability in the absence of a surfactant or a polymer dispersant, and containing a polymer component that is initially adsorbed into the dye to achieve storage stability over a long period of time. They also developed an aqueous inkjet ink having ejection stability and dispersion stability sufficient for inkjet recording purposes to give a printed image of high quality and durability, which is achieved by incorporating the dispersible colorant described above. More specifically, the objects of the present invention can be described as follows.

1. A dispersible colorant containing a colorant and pseudo-fine dispersed particles of a polarizable polymer having a size smaller than the colorant particles, where the colorant and particles are attached to each other.

2. A dispersible colorant containing a colorant and pseudo-fine dispersed particles of a polarizable polymer having a size smaller than the colorant particles, where a plurality of particles are distributed on and attached to the colorant.

3. Dispersible dye according to claims 1 or 2, which has a density of surface functional groups of at least 250 μmol / g and not more than 1000 μmol / g.

4. Dispersible dye according to any one of claims 1 to 3, which has a surface energy of 70 mJ / m ² or less.

5. Dispersible dye according to any one of claims 1 to 4, in which the component copolymer containing pseudo-fine particles of a polarizable polymer has a glass transition temperature of at least -40 ° C and not more than 60 ° C.

6. Dispersible dye according to any one of claims 1 to 5, in which the pseudo-fine dispersed particles of the polarizable polymer contain a copolymer of monomer components containing at least one type of hydrophobic monomer and at least one type of hydrophilic monomer.

7. Dispersible dye according to claim 6, in which the hydrophobic monomer contains at least a monomer having a methyl group in position α and a radically polymerizable unsaturated double bond.

8. Dispersible dye according to any one of paragraphs.6 or 7, in which the hydrophobic monomer contains at least a compound of the type of (meth) acrylic ester.

9. The dispersible colorant of claim 8, wherein the hydrophobic monomer contains at least one compound selected from the group consisting of benzyl methacrylate and methyl methacrylate.

10. A dispersible colorant according to any one of claims 6 to 9, wherein the hydrophilic monomer contains at least an anionic monomer.

11. The dispersible colorant of claim 10, wherein the anionic monomer contains at least one compound selected from the group consisting of acrylic acid, methacrylic acid and p-styrenesulfonate salts.

12. A dispersible colorant according to any one of claims 6 to 9, wherein at least a cationic monomer is used as the hydrophilic monomer.

13. A method for producing a dispersible colorant, comprising the step of conducting an aqueous precipitation polymerization process capable of radical polymerizing a monomer in an aqueous dispersion of a water-insoluble colorant using a radical water polymerization initiator to combine a water-insoluble colorant with pseudo-fine dispersed particles of a polarizable polymer.

14. A method of producing a dispersible colorant, comprising the steps of (1) conducting an aqueous precipitation polymerization process capable of radical polymerizing a monomer in an aqueous dispersion of a water-insoluble colorant using a radical water polymerization initiator to combine a water-insoluble colorant with pseudo-fine dispersed particles of a polarizable dye; and

(2) product cleaning.

15. The method of producing a dispersible dye according to claims 13 or 14, wherein the aqueous dispersion of a water-insoluble dye is an aqueous solution containing a pigment dispersed with a polymer dispersant having an acid number of at least 100 and not more than 250.

16. The method of obtaining a dispersible dye according to clause 15, in which the dispersant is a copolymer of monomer components containing at least one type of monomer selected from the group consisting of acrylic acid, methacrylic acid and styrene monomer.

17. A method for producing a dispersible colorant according to claims 15 or 16, wherein the initiator of radical polymerization in water is anionic or ampholytic.

18. The method of producing a dispersible dye according to claims 13 or 14, wherein the aqueous dispersion of the water-insoluble dye is an aqueous solution containing a pigment dispersed with a polymer dispersant having an acid number of at least 150 and not more than 300.

19. The method of obtaining a dispersible dye according to claim 18, in which the initiator of radical polymerization in water is cationic or ampholytic.

20. A method for producing a dispersible colorant according to any one of claims 13-19, wherein the radically polymerizable monomer component is added to the polymerization system.

21. A method for producing a dispersible colorant according to any one of claims 13-20, wherein the radically polymerizable monomer component contains at least one type of hydrophobic monomer and at least one type of hydrophilic monomer.

22. The method of producing a dispersible dye according to any one of paragraphs.13-21, in which the initiator of radical polymerization in water is an initiator of azo-base polymerization in water.

23. Dispersible dye obtained by the method according to any one of paragraphs.13-22.

24. Aqueous inks containing a dispersible colorant according to any one of claims 1 to 12 and 23.

25. Aqueous ink containing a dispersible colorant containing a colorant and pseudo-fine dispersed particles of a polarizable polymer having a size smaller than the colorant particles, where the colorant and particles are attached to each other, and further comprising at least one type of fine dispersed particles of a self-dispersible polymer.

26. The aqueous ink of claim 25, wherein the polymer component that makes up the pseudo-finely dispersed polarizable particles and the polymer component that makes up at least one type of self-dispersing polymer particles comprise a polymerization product of a mixture comprising at least one type common monomer component.

27. The aqueous ink of claim 26, wherein the polymer component, which is at least one type of pseudo-finely dispersed polarizable particles, and the polymer component, which is at least one type of self-dispersing polymer particles, contains a polymerization product of a mixture comprising at least one type of common monomeric component.

28. Aqueous ink containing a dispersible colorant containing a colorant and negatively polarizable pseudo-fine dispersed particles of a polarizable polymer having a size smaller than the colorant particles, where the colorant and particles are attached to each other, and where the dispersible colorant has an average surface zeta potential of at least -80 mV and not more than -15 mV in an aqueous medium, which is part of aqueous ink, and the distribution of the surface zeta potential is less than 50, expressed as a standard deviation.

29. Aqueous ink containing a dispersible colorant containing a colorant and positively polarizable pseudo fine dispersed particles of a polarizable polymer having a size smaller than the colorant particles, where the colorant and particles are attached to each other, and where the dispersible colorant has an average surface zeta potential of at least +10 mV and not more than +60 mV in an aqueous medium, which is part of aqueous ink, and the distribution of the surface zeta potential is less than 50, expressed as a standard deviation.

30. Aqueous ink according to any one of paragraphs.24-29, where the dye included in the dispersible dye is a pigment, and where the ratio of the total polymer component to pigment (polymer / pigment or B / P mass.) Is not less than 0.3 and not more than 4.0.

31. An ink tank containing aqueous ink according to any one of paragraphs.24-30.

32. Inkjet recording device for obtaining images using ink according to any one of paragraphs.24-30.

33. The method of inkjet recording for obtaining images using aqueous ink according to any one of paragraphs.24-30 using an inkjet recording device.

34. The image obtained by the method of inkjet recording using aqueous ink according to any one of paragraphs.24-30 using an inkjet recording device.

The present invention provides a dispersible dye, which has a sufficiently high dispersion stability, with a high density of functional groups on the surface, contains a polymer component on the surface and has virtually no tendency to separate from the surface, and also provides a method for the simple preparation of a dispersible dye.

The present invention also provides a dispersible colorant having other advantages, for example, the ability to quickly dry on the recording substrate, the high scratch resistance of the recording substrate, and the excellent ejection characteristics exhibited by the inkjet recording apparatus.

Other advantages of the dispersible colorant in accordance with this invention are excellent color development properties and suitability for use in high or low pH environments. The present invention also provides a method for easily producing a dispersible colorant, which is another advantage of the present invention.

The present invention also provides aqueous inks suitable for use on a highly glossy or glossy recording substrate, having high scratch resistance on the glossy recording substrate and having excellent storage stability over a long period of time, which is another advantage of the present invention.

The present invention provides aqueous inks having sufficient ejection stability and dispersion stability for inkjet recording purposes and allowing printing plates with high image quality and durability due to the introduction of dispersible dye therein, and also provides an ink storage tank, an inkjet recording device, an inkjet method recordings and images obtained by the method of inkjet recording using aqueous ink.

Brief Description of the Drawings

On figa and 1B schematically shows the basic structure of the dispersible dye in accordance with this invention with attached pseudo-fine particles of a polarizable polymer.

On each of Fig.2A, 2B, 2C and 2D presents the characteristic stages of the method in accordance with this invention.

Figure 3 schematically shows the stage of formation of pseudo-fine dispersed particles of a polarizable polymer and another stage of attaching these particles to a dye in accordance with the method of this invention.

Figure 4 presents an enlarged pseudo-fine dispersed particles of a polarizable polymer in accordance with this invention, located on the contact surface of the dye to which they are attached.

Figure 5 shows an enlarged contact surface on which pseudo-fine particles of a polarizable polymer are attached to a dye in accordance with this invention.

FIGS. 6A and 6B schematically illustrate the phenomenon of pigment detachment taking place when modifying an organic pigment with a hydrophilic group, which is described in Japanese Patent Application Laid-Open No. H10-195360.

FIGS. 7A, 7B, and 7C schematically show agglomeration conditions of a dispersible colorant on a recording substrate.

BEST MODE FOR CARRYING OUT THE INVENTION

The invention is described in more detail in the variants of its implementation, which are considered the best ways. By the term “dispersible colorant” as used herein is meant a colorant that can be substantially dispersed in water or liquid ink medium in the absence of surfactants or polymeric dispersants, for example, a self-dispersible colorant.

A first embodiment of the invention is a dye and pseudo fine particles of a polarizable polymer, where dye particles are attached to the polymer particles. On figa and 1B schematically shows the dye 1, to which the particles 2 are attached, which is a feature of the present invention. 2B schematically shows pseudo-fine dispersed particles of a polarizable polymer 2 attached to the surface of a dye 1, being partially condensed in part 2 '.

The dye is provided with a charge, which is determined by the pseudo-finely dispersed particles of the polarizable polymer attached to its surface so that the dye can be dispersed in water or an aqueous ink medium. In this way, a dispersible colorant is obtained. At the same time, it has a high degree of adhesion to the recording substrate due to the presence of a polymer component on its surface. Moreover, the dispersible dye in accordance with this invention has high storage stability over a long period of time due to the pseudo-fine particles of a polarizable polymer attached to the surface of the dye, and not the physical adsorption of the polymer component, which is also a hallmark of the dispersible dye in accordance with this invention , which is difficult to separate from the surface.

The pseudo-finely dispersed particles of a polarizable polymer according to this invention consist of a polymer agglomerate in which the polymer components are highly agglomerated with each other, preferably have many cross-links within (the polymer agglomerate consists of a polymer component constantly present in the form of finely dispersed particles, which can be agglomerated in other finely dispersed particles. The pseudo-finely dispersed particles of a polarizable polymer are described in detail below. e.

The pseudo-finely dispersed particles of the polarizable polymer are attached to the dye in accordance with this invention due to the strong interaction between them. It is believed that it is achieved due to the following phenomenon. Figure 4 schematically shows an enlarged contact surface on which pseudo-finely dispersed polarizable particles come into contact with a dye. It is necessary, firstly, to note that pseudo fine dispersed particles of a polarizable polymer are formed from a polymer consisting of compositions of various monomer units woven together. The polymer in certain places takes a variety of structures on the surface of contact with the dye and, therefore, has surface energy distributed locally. The dye and polymer are firmly attached to each other in certain places in which their surface energies, determined by the chemical and surface structure, coincide with each other (dark circles in Figure 4). There are many places on the surface in which they coincide with each other (places 10 in FIG. 4). It is believed that the particles are attached to the dye in such places due to the strong interaction in accordance with this invention.

Each of the pseudo-finely dispersed particles of the polarizable polymer consists of polymers that interact strongly with each other with the conditional formation of physical cross-links. This prevents the particles from separating from the dye or polymer component having a hydrophilic group, and the constant leaching of particles, even if the particles contain many hydrophilic groups. On the contrary, the dye obtained by encapsulation (described, for example, in Japanese Patent Application Laid-Open No. H8-183920) does not always demonstrate sufficient storage stability over a long period of time, since a strongly hydrophilic polymer cannot be firmly bound to the dye.

Pseudo-finely dispersed particles of a polarizable polymer attached to a dye to obtain a dispersible dye according to this invention have another advantage, which is an increased specific surface area due to fixation morphology. The increased specific surface very effectively contributes to the appearance of a charge on the particles and on the surface of the dye. As a result, the surface of the dispersible colorant is very heavily charged. In other words, the dispersible dye in accordance with this invention has a morphology in which its surface is charged more efficiently and more strongly, and it has a higher dispersion stability than the dye coated with a polymer shell described in Japanese Patent Application Laid-Open No. H8- 183920, even if the polymer component has a lower acid or amine number.

In general, organic pigments are not solubilized (suitable pigments) when their color-bearing molecules crystallize by strong interaction. When using organic pigment as a colorant for a dispersible colorant in accordance with this invention, pseudo-fine particles of a polarizable polymer are attached to the pigment particles over several dye molecules, as shown in FIG. 5, due to the many interaction points on the contact surface between the pseudo-fine dispersed polarizable particles and the dye, as described above. Therefore, “pigment detachment” (shown in FIGS. 6A and 6B) caused by a dye becoming locally hydrophilic should not occur in this invention. When using organic pigment as a dye, it is preferable that the pseudo-finely dispersed particles of the polarizable polymer have a smaller size than the particles of the dispersed pigment, but larger than the dye molecules, which gives a dispersible dye containing a highly dispersible pigment, without destroying the crystal structure of the pigment.

The conditions for the “attachment” of pseudo-fine dispersed particles of a polarizable polymer to a dye in this invention can simply be confirmed by the following method, which involves separation in three stages. In a first step, the test dye is separated from another water-soluble component (including a water-soluble polymer) present in the ink or aqueous dispersion. In the second stage, the dye and the water-insoluble polymer component are separated from the precipitate obtained in the first stage. In the third stage, the weakly adsorbed polymer component and the dispersible dye, to which pseudo fine particles of the polarizable polymer are attached, are separated for quantitative analysis of the polymer component in the supernatant obtained in the third stage, and the precipitate obtained in the second stage is compared with the precipitate obtained in the third stage. This method can confirm the conditions under which pseudo fine particles of a polarizable polymer are attached to a dye.

More specifically, the conditions can be confirmed by the following methods. An ink or an aqueous dispersion (20 g) is obtained in which dye is dispersed in an amount of about 10 wt.% Of the total mass of solids, and centrifuged at 12,000 rpm for 60 minutes in the first stage. The obtained precipitate containing a dye deposited in the lower layer was redispersed in an almost triple volume of pure water and centrifuged at 80,000 rpm for 90 minutes in the second stage. Then, the obtained precipitate containing a dye deposited in the lower layer is redispersed in a triple volume of pure water and centrifuged again at 80,000 rpm for 90 minutes in the third stage. The resulting precipitate containing dye deposited in the lower layer is collected from the system. The precipitate obtained in the second and third stages is dried in vacuum at a temperature of 30 ° C for 18 hours and studied using a scanning electron microscope with an increase of 50,000, each sample containing about 0.5 g of solids. If the dispersible dye under study has many finely dispersed particles or similar agglomerates attached to the surface, and the precipitate obtained in the second and third stages has the same morphology, then it is believed that the pseudo fine dispersed particles of the polarizable polymer are attached to the dye. In addition, about half of the upper supernatant obtained in the third stage is slowly collected from the system and dried at 60 ° C for 8 hours to determine the solids content based on the difference in weight before and after drying. If it is less than 1%, it is believed that the pseudo fine dispersed particles of the polarizable polymer are not separated from the dispersible dye, and these particles are attached to the dye.

The separation conditions described above are a preferred example, but any methodology can be used to assess whether the dye is a dispersible dye in accordance with this invention if it satisfies the separation conditions in three stages. More specifically, in the first step, the dye present in the ink or aqueous dispersion is separated and the polymer components adsorbed therefrom from water-soluble components. In a second step, the dye and the polymer component attached to it are separated from the other polymer component (s) adsorbed into the dye. In a third step, it is confirmed that the polymer component attached to the dye does not separate from the dye. Needless to say, any technique that can meet the goals of each stage can be applied, whether it is known or new. They may include more or less than three stages.

A second embodiment of the invention is a dispersible colorant that is self-dispersible, with pseudo-fine particles of a polarizable polymer 2, attached to a water-insoluble colorant 1. As described above, the dispersible colorant in accordance with this invention is self-dispersible, i.e. it can be stably dispersed in water and aqueous ink, especially in the absence of surfactants or polymer dispersants. Definitions and assessment method are described below. The dispersible colorant in accordance with this invention can be dispensed without the use of a polymer dispersant, another polymer component or surfactants that can separate from the dye for extended periods and which are traditionally used to stabilize the dye dispersion. As a result, the dispersible colorant in accordance with this invention gives another advantage to aqueous ink, namely a greater degree of freedom in the selection of the composition of components other than the dispersible colorant. Therefore, aqueous ink containing a dispersible colorant in accordance with this invention can provide a sufficiently high print concentration even on an ink-permeable recording substrate, for example, ordinary printing paper.

The self-dispersibility of a dispersible colorant in accordance with this invention can be confirmed, for example, by the following method. The ink or aqueous dispersion in which the dye is dispersed is diluted ten times with pure water and concentrated to the initial concentration using an ultrafilter trapping a molecular weight of 50,000. The concentrated solution is centrifuged at 12,000 rpm for 2 hours, and the resulting precipitate is collected and redispersed in clean water. The dye is considered self-dispersible if the precipitate is well re-dispersed. Good or bad whether it is dispersible, evaluate, taking into account the following observations; the dispersion is visually homogeneous, after the solution has matured for 1-2 hours, no visible precipitate is observed, or the precipitate, if any, can be dispersed by lightly shaking the solution, and the diameter of the dispersed particles, determined by dynamic light scattering, is not more than 2 times larger particle diameter before processing.

As described above, the dispersible dye in accordance with this invention has a large specific surface area, which is obtained by attaching pseudo-fine dispersed particles of a polarizable polymer to the dye, and has excellent storage stability when heavily charged over a large area. More preferred results can be obtained by using pseudo-fine dispersed particles of a polarizable polymer, attached in large quantities to a dye in a uniform distribution. It is particularly preferred that these particles are at a certain distance from each other and, preferably, uniformly distributed. Even more preferably, the surface of the dye between such particles should be open. Such morphologies can be confirmed using a transmission or scanning electron microscope. In other words, microscopic studies can confirm whether the particles are at a certain distance from each other, or if the surface of the dye is open between such particles. Such particles may be places closer to each other or condensed with each other in some cases. However, in the art it is obvious that such particles are attached to the dye, if in general they are at a certain distance from each other or the surface of the dye between such particles is open, and these conditions prevail.

Moreover, it was found that aqueous ink containing a dispersible colorant in accordance with this invention, quickly dry on a recording substrate, presumably due to the mechanism below, which, however, is not fully confirmed. The dispersible colorant is dispersible in the ink with pseudo fine particles of a polarizable polymer attached to its surface, as described above. When ink enters the recording substrate, the solvent in the ink is absorbed into the fine pores of the substrate (voids between the paper pulp fibers, or the fine pores in the receiving layer for coated paper or glossy paper) due to the capillarity phenomenon. The dispersible colorant in accordance with this invention then forms many small gaps in the area over which the colorant is in contact with each other and the pseudo fine particles of the polarizable polymer are uniformly distributed, which is the result of its morphological characteristics. Therefore, the ink solvent present between the dye particles is rapidly absorbed into the recording substrate due to the capillarity phenomenon. Aqueous inks in accordance with this invention have more preferred drying speed characteristics if they contain a dispersible colorant containing pseudo fine particles of a polarizable polymer uniformly distributed on the surface. This observation confirms the above mechanism of quick drying.

The dispersible colorant in accordance with this invention preferably has functional groups on the surface with a density of not less than 250 μmol / g and not more than 1000 μmol / g, more preferably not less than 290 μmol / g and not more than 900 μmol / g. It may have worse storage stability over an extended period of time if the density is less than indicated. At a significantly higher density, on the other hand, it can be difficult to withstand a high print concentration due to the excessive stability of the dispersion and, therefore, the permeability of the recording substrate. The density of surface functional groups is more preferably not less than 350 μmol / g and not more than 800 μmol / g when used as a dye soot, since soot has a higher specific gravity, requiring higher dispersion stability and a higher black concentration on the recording substrate . The density of surface functional groups can be determined, for example, by the following method, if the dispersible dye is negatively charged. An aqueous dispersion or ink containing a dispersible colorant is diluted with excess hydrochloric acid (HCl) and centrifuged at 20,000 rpm for 1 hour. The precipitate obtained is collected and redispersed in pure water, and the concentration of solids in the precipitate is determined by drying. The redispersed precipitate is weighed and then a known amount of sodium bicarbonate is added to it. The mixture was stirred to obtain a dispersion, which was centrifuged at 80,000 rpm for 2 hours. The supernatant is weighed and titrated with 0.1 N hydrochloric acid to neutralize, which allows you to determine the density of surface functional groups (mol / g - dye) by subtracting a known amount of sodium bicarbonate from the amount to be neutralized. If the dispersible dye is charged with a cationic group as a polar group, the density of the surface functional groups is determined by a similar method except that hydrochloric acid and sodium bicarbonate are replaced by sodium hydroxide (NaOH) and ammonium chloride, respectively.

A dispersible colorant having a surface energy of 70 mJ / m ² or less is one of the preferred embodiments of the present invention. The inventors have found that a dispersible colorant can provide adequate fixation to the recording substrate if its surface energy is in the indicated range. A dye having a surface energy significantly greater than 70 mJ / m ² may make it difficult to uniformly release the dye from the aqueous medium of the ink due to excessive hydrophilicity of the surface of the dispersible dye, and may make it difficult to uniformly dry the printed image. In addition, a dried image may not be sufficiently resistant to water, presumably due to the strong hydrophilicity of the surface of the dispersible dye, which causes the dye to redisperse on the recording substrate after it agglomerates if the image is in contact with water or a water marker. The surface energy of the dispersible dye in accordance with this invention can be controlled by the surface charge of the dye, the structure of the functional group, and the chemical and surface structure of the pseudo-finely dispersed particles of the polarizable polymer attached to the dye. In addition, the chemical and surface structure of the pseudo-fine dispersed particles of the polarizable polymer can be controlled by any polymerization initiator and monomer components during particle synthesis.

"Surface energy" in this description means the free energy on the contact surface between the materials and depends on the chemical structure of the contact surface. Material with higher surface energy is more wettable and compatible with water. The surface energy of a dispersible colorant is determined as the value determined using a Surface Measurement System inverse gas chromatograph. More specifically, it is determined by extrapolating the gas retention time for a dispersible colorant, solidified into powder, as a stationary phase, and organic gas with different polarity in the mobile phase.

The following describes each component dispersible dye in accordance with this invention.

Dye

Described dye, which is one of the components of the dispersible dye in accordance with this invention. It can be any known or new dye. However, it is preferable that it is a hydrophobic dye, inorganic pigment, organic pigment, metallic colloid or colored polymer powder, which is insoluble in water and can be stably dispersed in water in the presence of a dispersant. Preferably, its particle diameter is, in dispersion, from 0.01 to 0.5 μm (from 10 to 500 nm), more preferably from 0.03 to 0.3 μm (from 30 to 300 nm). The dispersible colorant in accordance with this invention, the particles of which, in the dispersion, have a diameter within the above ranges, is an excellent dispersible colorant for aqueous inks, since such a colorant has a high stainability and gives the images a high degree of environmental resistance. The diameter in the dispersion is defined as the cumulative average diameter determined by dynamic light scattering.

Inorganic pigments used for the dye include carbon black, titanium oxide, white zinc, zinc oxide, tripon, iron oxide, alumina, silica, kaolinite, montmorillonite, talc, barium sulfate, calcium carbonate, quartz, alumina, red cadmium, red iron oxide, red molybdenum, chromium vermillion, orange molybdate, yellow lead, yellow chromium, yellow cadmium, yellow iron oxide, yellow titanium, chromium oxide, pyridian, green cobalt, green titanium cobalt, green chromium cobalt, saturated blue, ultramarine blue, b rlinskuyu blue, cobalt blue, cerulean blue, manganese violet, cobalt violet and mica.

Organic pigments used in this invention include those based on azo compounds, azomethine, polyazo, phthalocyanite, quinacridone, anthraquinone, indigo, thioindigo, quinophthalone, benzimidazolone, isoindoline and isoindolinone.

Organic, water-insoluble dyes used in accordance with this invention include hydrophobic dyes, for example, based on azo compounds, anthraquinone, indigo, phthalocyanate, carbonyl, quinonymine, methine, quinoline and nitro. Among them, dispersible colorants are particularly preferred.

Pseudo-fine dispersed particles of a polarizable polymer

Pseudo-finely dispersed particles of a polarizable polymer, which are another component of a dispersible dye in accordance with this invention, are defined as small polymer agglomerates with a sufficiently high degree of polymerization, having small dispersible units (diameter in dispersion) in water (or ink) by which they are attached to the dye . A small agglomerate is morphologically close to a sphere in a pseudo-species or in the form of agglomerated finely dispersed particles (pseudo-finely dispersed particles of a polarizable polymer) having the same size in a certain range. The polymer component of the pseudo-fine dispersed particles of the polarizable polymer preferably consists of particles physically or chemically crosslinked to each other. Whether they are cross-linked with each other can be checked using, for example, the following method. The polymer component, which consists of pseudo-finely dispersed polarizable particles, is evaluated in advance by a known analysis method and a linear polymer having the same chemical structure (or composition of monomer units) is synthesized by polymerization in solution. Then the pseudo fine particles of the polarizable polymer and the polymer are mixed in an organic solvent, which is a good solvent for the polymer, to compare their solubility. Pseudo-finely dispersed particles of a polarizable polymer are considered cross-linked internally if they have a lower solubility compared to the polymer.

Another preferred embodiment are particles having a cumulative average diameter of not less than 10 nm and not more than 200 nm, as measured by dynamic light scattering. More preferably, the particles have a coefficient of polydispersity of the diameter in the dispersion of at least 0.2, from the point of view of stability during storage of the dispersible dye for a long period of time. The stabilization of the finely dispersed dye, which is one of the main objectives of the present invention, cannot be achieved if the dispersed particles have an average diameter of more than 200 nm or a polydispersity coefficient of more than 0.2. On the other hand, pseudo-fine dispersed particles of a polarizable polymer having an average diameter of less than 10 nm may not have the advantages of the present invention, since they will not be able to sufficiently preserve the morphology of the pseudo-fine particles of a polarizable polymer, and the polymer will more readily dissolve in water. Dispersed particles having an average diameter of not less than 10 nm and not more than 200 nm can effectively give a stable dye dispersion, which is achieved by attaching pseudo-fine dispersed particles of a polarizable polymer to the dye, since they are smaller than the dye particles. The preferred embodiments presented above are valid for cases where the diameter of the dispersed pseudo fine particles of a polarizable polymer cannot be measured. In this case, the diameter can be determined using an electron microscope. The preferred diameter range should be as close to or as indicated above.

If the dye is an organic pigment, it is particularly preferred that the dispersed pseudo-fine dispersed particles of the polarizable polymer have an average diameter within the above ranges and, at the same time, are smaller than the particles of the dispersible pigment and larger than the molecules of the dispersed dye, since when the data are satisfied conditions can be obtained very stable in structure and highly dispersible dye.

The polarizable particles in accordance with this invention are those particles that have a certain ionized functional group in an aqueous medium, preferably self-dispersing due to its polarizability. Whether pseudo-finely dispersed particles are polarizable can be confirmed by one of the following known methods; measuring the zeta potential of the particle surface, potentiometric titration to determine the density of functional groups described below, confirming the dependence of the stability of the dispersion of pseudo-fine particles of a polarizable polymer on the concentration of the electrolyte after the aqueous dispersion of particles is mixed with the electrolyte, and analysis of the chemical structure of the pseudo-fine particles of a polarizable polymer to confirm the presence of ionic functional groups.

The polymer component of the pseudo-fine dispersed particles of the polarizable polymer is not limited and can be selected from any natural or synthetic polymer compound, as well as from the polymer compound obtained in accordance with this invention. The polymers used as the polymer component in accordance with this invention include acrylic, styrene / acrylic, polyester, polyurethane and polyurea, as well as polysaccharides and polypeptides. In particular, polymers and copolymers having a radically polymerizable unsaturated bond, which are characterized by acrylic, styrene / acrylic polymers, are preferred since they can be widely used and are easily processed to obtain characteristics of pseudo-finely dispersed polarizable particles.

Monomers having a radical polymerizable unsaturated bond (hereinafter referred to as "radical polymerizable monomers" or simply monomers), preferably used in accordance with this invention, include hydrophobic monomers such as (meth) acrylic esters, for example methyl acrylate, ethyl acrylate, isopropyl acrylate, n propyl acrylate, n-butyl acrylate, tert-butyl acrylate, benzyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, tridecylmeth rilat and benzyl; styrene-based monomers, for example styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene and p-tert-butylstyrene; itaconic acid esters, for example benzyl lithic acid; maleic acid esters, for example dimethyl maleate; fumaric acid esters, for example dimethyl fumarate; and acrylonitrile, methacrylonylryl and vinyl acetate.

The following compounds, which belong to the category of hydrophilic monomers, are also preferably used in accordance with this invention: monomers having an anionic group, such as monomers having a carboxyl group, for example, acrylic acid, methacrylic acid, crotonic acid, ethacrylic acid, propyl acrylate, isopropyl acrylate tacon acid, fumaric acid and their salts; monomers having a sulfonic acid group, for example styrene sulfonate, 2-propyl acrylamide sulfonate, (acrylic acid) -2-ethyl sulfonate, (methacrylic acid) -2-ethyl sulfonate, butyl acrylamide sulfonate and their salts; and monomers having a phosphonic acid group, for example (methacrylic acid) -2-ethylphosphonate and (acrylic acid) -2-ethylphosphonate. Among them, acrylic acid and methacrylic acid are more preferred.

Monomers having a cationic group include monomers having a primary amino group, for example aminoethyl acrylate, aminopropyl acrylate, amide methacrylate, amino ethyl methacrylate, aminopropyl methacrylate; monomers having a secondary amino group, for example methylaminoethyl acrylate, methylaminopropyl acrylate, ethylamino ethyl acrylate, ethyl aminopropyl acrylate, methylamino ethyl methacrylate, methyl aminopropyl methacrylate, ethyl amino ethyl methacrylate and ethyl aminopropyl methacrylate; monomers having a tertiary amino group, for example dimethylaminoethyl acrylate, diethylaminoethyl acrylate, dimethylaminopropyl acrylate, diethylaminopropyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminopropyl methacrylate and diethylaminopropyl methacrylate; monomers having a quaternary ammonium group, for example, dimethylaminoethyl methyl acrylate chloride, dimethylaminoethyl methyl methacrylate chloride, dimethylaminoethyl benzyl acrylate chloride, dimethylaminoethyl benzyl methacrylate chloride; and vinyl imidazoles.

Nonionic hydrophilic monomers include compounds having both a radical polymerizable unsaturated bond and a hydroxyl group that are highly hydrophilic. These include hydroxymethyl (meth) acrylate, hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate. Other known or new oligomers and macronomers of various types may be used without limitation.

The use of cross-linked monomer is another preferred option. Such monomers include divinylbenzene, allyl (meth) acrylate and methylene bisacrylamide. Other known or new cross-linked monomers of various types may be used.

The various characteristics of the dispersible colorant and the pseudo-fine particles of the polarizable polymer can be suitably controlled by a variety of control parameters, such as the type and ratio of copolymerization of the monomer, which is the pseudo-fine particles of the polarizable polymer, and the type and concentration of the polymerization initiator to polymerize the monomer. The use of a copolymer consisting of at least one type of hydrophobic monomer and at least one type of hydrophilic monomer selected from the above for pseudo fine particles of a polarizable polymer is one of the particularly preferred options. The use of at least one type of hydrophobic monomer gives particles with good dye attachment properties and thermal stability, and the use of at least one type of hydrophilic monomer gives good controllability of morphology and dispersion stability. Therefore, the introduction of such monomers at the same time can produce pseudo fine dispersed particles of a polarizable polymer that adhere well to the dye and have good dispersion stability. Pseudo-finely dispersed particles of a polarizable polymer attached to each other, to a dispersible colorant and / or colorant in accordance with this invention, can have one or more additional functions, due to the correct choice of the type of monomer and its copolymerization ratio for a polymer component that has one or more functions in addition to those described above.

For example, in one embodiment, at least one type of hydrophobic monomer is used that has a methyl group at position α and a radically polymerizable unsaturated bond. Aqueous inks containing a dispersible colorant with pseudo-finely dispersed particles of a polarizable polymer attached to the colorant have very good emissivity, in particular in thermal inkjet recordings where ink is emitted using thermal energy if a radically polymerizable monomer having methyl type is used as the polarizable particle. a group at position α. Improved ejection is considered the result of depolymerization of a polymer consisting of a radically polymerizable monomer having a methyl group in the α position at high temperatures to prevent the polymer from sticking to the inside of the ejection port when the ink is exposed to thermal energy, although this concept has not yet been fully confirmed.

In another preferred embodiment, a hydrophobic monomer is used that contains at least an acrylic or methacrylic acid alkyl ester (hereinafter referred to as (meth) acrylic acid alkyl ester). The (meth) acrylic acid alkyl ester has a high degree of attachment to the dye and copolymerizes to a large extent with the hydrophilic monomer component and, therefore, gives favorable characteristics to the pseudo-fine dispersed particles of the polarizable polymer, for example, uniform surface characteristics and uniform attachment to the dye.

Among the preferred hydrophobic monomers, benzyl methacrylate and methyl methacrylate are more preferred, and it is particularly preferred to use at least one of them, since they give, in addition to the above characteristics, favorable characteristics of heat resistance and transparency to the pseudo fine particles of a polarizable polymer. As a result, a dispersible colorant containing such particles has an excellent degree of color development.

As described above, the characteristics of the pseudo-fine particles of the polarizable polymer attached to the dispersible colorant of the present invention and / or the colorant thereof can be properly controlled by the choice of the type and ratio of copolymerization of the monomer that makes up the particles. The copolymer component of the particles preferably has a glass transition temperature of not less than -40 ° C and not more than 60 ° C, more preferably not less than -30 ° C and not more than 55 ° C, even more preferably not less than -25 ° C and not more than 53 ° C, which is another preferred option. To obtain such particles, a monomer that produces a homopolymer having a low glass transition temperature is selected from the preferred monomers described above. The combination of n-butyl acrylate and acrylic acid in an appropriate ratio is one of the preferred monomeric components. The combination of ethyl methacrylate and methacrylic acid in an appropriate ratio is also one of the preferred monomeric components. The glass transition temperature of pseudo fine particles of a polarizable polymer can be determined by analysis on a differential scanning calorimeter. For example, it is determined on the analyzer (METTLER, DSC822e). The analysis is described in detail in the examples.

A dispersible colorant containing a copolymer component having a glass transition temperature of not less than -40 ° C and not more than 60 ° C is obtained in a film formed with a dye on a recording substrate to obtain a strong, colored film due to the excellent properties of pseudo fine particles of polarizable particles to form a film polymer. Therefore, a dispersible colorant having the composition described above produces high scratch resistance images even if it is formed on a glossy recording substrate, which is not very preferred in terms of scratch resistance of the image.

Aqueous ink containing a dispersible colorant in accordance with this invention containing a copolymer component having a glass transition temperature within the above ranges gives an image that is highly scratch resistant even if it is applied to a recording substrate at temperatures not significantly different from room temperature . The reason for this phenomenon is not clear, but the authors of the present invention suggest the following mechanism. The glass transition temperature of the polymer, determined by analysis on a differential scanning calorimeter, is generally characteristic of the polymer in the dried state, and it is known to be lower for a polymer that contains absorbed water. In the pseudo-fine dispersed particles of the polarizable polymer that make up the dispersible colorant of the present invention, the polymer contains absorbed water in at least that part that is around the ionic functional group. Pseudo-finely dispersed particles of a polarizable polymer have a lower glass transition temperature than measured if they comprise a dispersible colorant in an aqueous medium to produce aqueous ink. Therefore, such particles can exhibit film formation and adhesion characteristics when they are on a recording substrate. The authors of the present invention found that such particles demonstrate these characteristics if their glass transition temperature is in the range of not less than -30 ° C and not more than 55 ° C, more preferably not less than -25 ° C and not more than 53 ° C, and give an even more favorable result if the polymer component for such particles contains at least one type of hydrophilic monomer.

A composition with an anionic monomer as a hydrophilic monomer is another preferred embodiment of the pseudo-finely dispersed particles of a polarizable polymer constituting a copolymer containing at least one type of hydrophobic monomer and at least one type of hydrophilic monomer. In particular, introducing an anionic monomer can introduce more anionic groups into the pseudo-fine dispersed particles of the polarizable polymer, and therefore it is also an effective practice to control the density of surface functional groups on the surface of the dye at the desired level, as described above. A dispersible colorant may exhibit higher dispersion stability at high pH if it contains an anionic monomer.

The anionic monomer used in accordance with this invention is not limited if it has a functional group that is anionic in water. Particularly preferred examples include acrylic acid, methacrylic acid, p-styrenesulfonate and their salts, considered in terms of copolymerizability with another monomer component, availability and anionic strength.

If the above composition also contains at least a cationic monomer as a hydrophilic monomer, the dispersible colorant will have higher dispersion stability in a low pH environment. Such compositions, therefore, are another preferred option. The cationic monomer used in accordance with this invention is not limited if it has a functional group that is cationic in water. Of the radical polymerizable monomers mentioned above, preferably those having a cationic group are used.

Synthesis of pseudo fine dispersed particles of a polarizable polymer and their attachment to a dye.

Pseudo-finely dispersed particles of a polarizable polymer can be synthesized by known techniques or methods and can be attached to a dye by a known dye preparation method. The authors of this invention have developed, as a result of extensive research, a method for easily producing a dispersible dye with desired characteristics, containing a dye and pseudo fine particles of a polarizable polymer having a size smaller than a dye where the dye and particles are attached to each other. A method of obtaining a dispersible dye in accordance with this invention, which is preferably carried out in this invention, is given below.

The inventors of the present invention have found that a dispersible colorant having the above characteristics can be very easily obtained by polymerization by precipitation in water, carried out under the following conditions.

First, a water-insoluble colorant is dispersed in the presence of a dispersant to form an aqueous solution of the dispersed colorant. The radical polymerizable monomer is then polymerized in the presence of a radical polymerization initiator in an aqueous dispersion by precipitation polymerization to attach the pseudo fine particles of the polarizable polymer to the dye. The dispersible colorant obtained by water-precipitation polymerization contains pseudo-fine dispersed particles of a polarizable polymer, which are also obtained in this method, uniformly distributed, attached to the colorant. The dispersible colorant has excellent dispersion stability per se. The above-described preferred characteristics of the pseudo-finely dispersed particles of the polarizable polymer can be easily controlled during the polymerization by precipitation in water, while achieving the characteristics of the dye attachment indicated in this invention. Preferred variants of the above production method are described in detail below.

Dispersion of water-insoluble dye.

First, a water-insoluble colorant selected from the preferred embodiments of the invention is dispersed in the presence of a dispersant to form an aqueous dispersion. A dispersant for dispersing a dye in an aqueous medium is not limited and may be ionic or non-ionic. However, it is preferable to use a polymer dispersant or a water-soluble polymer compound to maintain the stability of the dispersion in the subsequent polymerization step. Particularly preferred is a radically polymerizable monomer that is sufficiently soluble in water and must be introduced into the surface of the dye particles at the polymerization stage. Even more preferably, it has a hydrophobic segment that provides adsorption centers for the hydrophobic monomer on the surface of the oil droplets. Even more preferably, it contains at least one type of hydrophobic monomer used in the subsequent polymerization step, as this may enhance the attachment of pseudo fine particles of the polarizable polymer to the dye in this step.

A method for producing a polymer dispersant or a water-soluble polymer compound used as a dispersant in accordance with this invention is not limited. For example, it can be prepared by reacting a monomer having an ionic group with another polymerizable monomer in a non-reactive solvent in the presence or absence of a catalyst. It has been found that good results can be obtained with a dispersant based on a styrene / acrylic polymer compound obtained by polymerizing the above monomer having an ionic group and a styrene monomer as main components, or based on an acrylic polymer compound having an ionic group obtained by polymerizing a monomer having an ionic group and an (meth) acrylic acid ester monomer having at least 5 carbon atoms as main components. It is preferable to use an anionic dispersant if a dispersible dye containing an anionic group is obtained, and a dispersant having a cationic or nonionic group if a dispersible dye having a cationic group is obtained.

If the attachment of pseudo-finely dispersed particles of a polarizable polymer to a dye is to be enhanced during the polymerization with precipitation in water and, at the same time, the dispersion stability is to be maintained at the polymerization stage, it is preferable to use an anionic dispersant having an acid number of at least 100 and not more than 250, or cationic dispersant having an amine number of not less than 150 and not more than 300. In the presence of a dispersant having an acid or amine number below the above limits, pseudotonodisperse The dispersed particles of the polarizable polymer may not retain good dispersibility, since the hydrophobic monomer is more compatible with the dispersant than with the dye during polymerization by precipitation in water, as a result of which the dispersant is separated from the surface of the dye before the pseudo fine particles of the polarizable polymer adhere to the dye. On the other hand, in the presence of a dispersant having an acid or amine number above the above limits, the attachment of pseudo fine particles of a polarizable polymer to the surface of the dye can be slowed down because it is very strong with respect to the effect of volume displacement or static repulsion on the surface of the dye. If an anionic dispersant is used, it should preferably have a carboxyl group as an anionic group, from the point of view of preventing the attachment of pseudo fine particles of a polarizable polymer to a dye.

In the step of dispersing a water-insoluble colorant to form an aqueous dispersion, the colorant preferably has a diameter of not less than 0.01 μm and not more than 0.5 μm (not less than 10 nm and not more than 500 nm), particularly preferably not less than 0.03 microns and not more than 0.3 microns (not less than 30 nm and not more than 300 nm), after dispersion. The diameter in the dispersion at this stage greatly affects the diameter in the dispersion of the resulting dispersible dye. Therefore, it is preferable that it is within the above limits, from the point of view of controlling the possibilities of the dye, the stability of the image to the environment and the stability of the dispersion.

The water-insoluble colorant in accordance with this invention preferably has a dispersed particle size close to a monodisperse distribution. In general, a dispersible colorant with pseudo-fine dispersed particles of a polarizable polymer attached to a colorant typically has a particle diameter distribution narrower than that in the aqueous dispersion processed in the polymerization step, as shown in Fig. 2B, although it mainly depends on a later distribution. It is important to narrow the distribution of the particle diameter of the dye, as this allows you to cause the attachment of pseudo-fine dispersed particles of a polarizable polymer to the dye by heteroagglomeration. The inventors have found that the use of a dye having a polydispersity coefficient of 0.25 or less provides a dispersible dye with excellent dispersion stability.

Different analytical techniques give different particle diameters of the dispersible colorant. In particular, organic pigment particles are rarely spherical. In this description, the particle diameter is represented by the average particle size and polydispersity coefficient measured by dynamic light scattering (analyzer: Otsuka Electronics ELS-8000) and determined by cumulative analysis.

The method of dispersing a water-insoluble dye in water is not limited as long as it is selected from methods giving a stable dispersion of the dye in water under the conditions described above, in the presence of a dispersant, also described above. It may be known or new, developed for the present invention. If the pigment is a water-insoluble colorant, the polymer dispersant is added in an amount of not less than 10% and not more than 130% by weight with respect to the weight of the pigment.

The water-insoluble dye in accordance with this invention is preferably not self-dispersible, since this allows you to control the characteristics of the dispersible dye obtained by the preferred embodiment of the pseudo-fine dispersed particles of the polarizable polymer described above.

The method for dispersing a dye in accordance with this invention is not limited insofar as it is widely used for dye and can be selected from those methods that use a dispersing machine, for example, a dye shaker, a sand mill, a three-shaft mill and the like, a homogenizer high pressure, for example microfluidizer, nanomizer or multimizer, or an ultrasonic dispersion machine.

Radical polymerization initiator

The radical polymerization initiator of the present invention is not limited as long as it is a well-known water soluble radical polymerization initiator.

Specific examples of a water soluble radical polymerization initiator include persulfates and water soluble azo compounds. It may be a reduction-oxidation initiator consisting of a combination of a water-soluble radical polymerization initiator and a reducing agent. More specifically, the optimal combination is created and applied depending on the characteristics of the dye, dispersant and monomer described above. Preferably, it is selected from initiators giving the remainder of the polymerization initiator having the same polarity sign as the surface characteristics of the resulting dispersible colorant. For example, it is selected from initiators giving a neutral or anionic residue of the polymerization initiator if a water-insoluble dye having an anionic group is obtained. This allows you to more effectively receive a surface charge. Similarly, it is preferably selected from initiators giving a neutral or cationic residue of the polymerization initiator if a dispersible dye having a cationic group is obtained.

The use of a water-soluble azo compound as a radical polymerization initiator (hereinafter referred to as an “aqueous azo-based radical polymerization initiator”) is another preferred embodiment of the present invention. Azo-based radical polymerization initiators, including water, are compounds having at least one azo group, where the azo group is decomposed by heat (or light) to produce radicals, thereby initiating polymerization. The azo-based radical polymerization initiator gives a lower pH in the polymerization system to the lower limit, since it interacts with persulfate and, therefore, more effectively controls the formation of large particles as a result of the poor dispersibility of the system. The azo-based radical polymerization initiator is used for the polymerization in accordance with this invention with a specific organic pigment, in particular a quinacridone-based pigment, since a water-insoluble colorant reduces the amount of unreacted monomer after polymerization and provides sufficient conversion. Therefore, this option is particularly preferred. The quinacridone-based pigment has a structure represented by the general formula (1):

More specifically, these pigments include PV (purple pigment) 19, PR (red pigment) 122, PR 192, PR 202, PR 206, PR 207 and PR 209, PR 122, as one of the preferred pigments in accordance with this invention, is presented general formula (1), where R ² and R ⁹ are each CH ₃ , and R ¹ , R ³ , R ⁴ , R ⁸ , R ¹⁰ and R ¹¹ are each N.

Azo compounds-based radical polymerization initiators preferred in accordance with this invention include those typically used for emulsion polymerization or the like. In addition, they may be new, designed for emulsion polymerization. More specifically, they include VA-080 (2,2'-azobis (2-methyl-N- (1,1-bis (hydroxymethyl) -2-hydroxyethyl) propionamide)), VA-086 (2,2'-azobis (2-methyl-N- (2-hydroxyethyl) propionamide)), VA-057 (2,2'-azobis (2- (N- (2-carboxyethyl) amidino) propane)), VA-058 (2,2 '-azobis (2- (3,4,5,6-tetrahydropyrimidin-2-yl) propane) dihydrochloride)), VA-060 (2,2'-azobis (2- (1- (2-hydroxyethyl) -2 -imidazolin-2-yl) propane) dihydrochloride)), V-50 (2,2'-azobis (2-amidinopropane) dihydrochloride)) and V-501 (4,4'-azobis (4-cyanopentanoic acid)) ( all supplied by Wako Pure Chemical Industries). Among the initiators of radical polymerization based on azo compounds, an initiator having a carboxylic acid group and an amino group, for example, VA-057 (2,2'-azobis (2- (N- (2-carboxyethyl) amidino) propane)), provides another advantage in addition to those described earlier. The initiator residue associated with the surface of the pseudo-finely dispersed particles of the polarizable polymer is ampholytic and gives a dispersible dye having good dispersion stability over a wide pH range. The use of such an initiator is another preferred option in accordance with this invention.

Radically Polymerizable Monomer

The radical polymerizable monomer for the process of this invention is a component that comprises pseudo fine particles of a polarizable polymer after undergoing the polymerization by precipitation in water as described above. It can be appropriately selected taking into account the characteristics of the pseudo-finely dispersed particles of the polarizable polymer and the resulting dispersible colorant, as described above for finely dispersed, finely dispersed polymer particles in water. The radical polymerizable monomer in accordance with this invention is not limited. It may be famous or new.

Water Deposition Polymerization

The following will describe preferred options for polymerization with precipitation in water as a stage of synthesis of pseudo fine particles of a polarizable polymer and their attachment to a dye, which is a feature of this invention. It should be understood that the invention is not limited to the options described below. 2A-2D schematically show this process. It is believed that the process includes the following steps for the preparation of a dispersible colorant. First, dye 1 is dispersed in an aqueous solution in the presence of dispersant 3 to obtain an aqueous dispersion (Fig. 2A). The dispersion of dye 1 is stabilized in the presence of an adsorbed dispersant 3, wherein the adsorption is thermally equilibrium. Then, the aqueous dispersion obtained above is heated with stirring, and the monomer component 4 is added to it together, for example, with the aqueous radical polymerization initiator 5 (Fig. 2B). The initiator 5 decomposes upon heating with the release of radicals, thereby enhancing the reaction between a hydrophobic monomer dissolved in trace amounts in the aqueous phase and a water-soluble monomer present in the aqueous phase.

Figure 3 schematically shows the stage of polymerization of monomer 4 to obtain a dispersible dye 6 (Fig.2C). As the reaction of the monomer 4 described above proceeds, the oligomer 1 formed by the polymerization of the monomer component becomes insoluble in water and becomes precipitate 8 after separation from the aqueous phase. The particles of the separated oligomer are not sufficiently stable in dispersion, and they combine with each other to produce pseudo fine particles of a polarizable polymer 2. These fine particles 2 undergo hetero-agglomeration with the hydrophobic dye surfaces in the aqueous dispersion as nuclei, and the polymer component that makes up the pseudo fine particles particles of polarizable polymer 2 are strongly adsorbed onto the surface of dye 1 due to hydrophobic interactions, whereas in pseudo on-dispersed particles of polarizable polymer 2 undergoes a polymerization reaction. As a result, these finely divided particles 2 are transformed into a form with a more energetically stable morphology, while increasing the number of adsorption centers. At the same time, to a large extent, physical cross-links are formed inside the pseudo-finely dispersed particles of the polarizable polymer 2, as a result of which the finely dispersed particles 2 solidify after reaching a morphology in which they are adsorbed more stably. On the other hand, the dye 1 stabilizes upon attachment of pseudo fine particles of the polarizable polymer 2 to it, which allows the dispersant adsorbed on it to separate from the surface.

Figure 4 schematically shows both sides of the contact surface between the pseudo-fine dispersed particles of the polarizable polymer 2 obtained above and the dye 1. As shown, the pseudo-fine dispersed particles of the polarizable polymer 2, which are agglomerates of the polymer component, have units of a hydrophilic monomer 9-1 and units of a hydrophobic monomer 9-2. They are distributed arbitrarily, which gives a distribution of local surface energy, and there are many adsorption centers 10 in which their surface energy coincides with the surface energy of the dye.

5 schematically shows an enlarged contact surface on which pseudo fine particles of a polarizable polymer 11 are attached to a portion of the particles of dye 1a. Pseudo-finely dispersed particles of the polarizable polymer 11 are adsorbed at the adsorption center 10 shown in FIG. 4 on the contact surface, attached to the dye, with stable morphology, which depends on the surface shape of the part of the dye 1a. As described above, the polymerization of pseudo-finely dispersed particles of a polarizable polymer also takes place at this stage, and the particles adhere to the dye after reaching a morphology in which they are adsorbed more stably. A dispersible colorant with the composition described above can be easily obtained using these steps (FIG. 20). In a system in which pseudo-fine dispersed particles of a polarizable polymer are sufficiently charged on the surface to be self-dispersing, they are separated from each other by (electro) static repulsion, while they are adsorbed on the dye and adhere to the dye during heteroagglomeration uniformly distributed on the surfaces of the dye particles. As a result, they obtain the preferred morphology described above.

The polymerization conditions depend on the characteristics of the polymerization initiator, dispersant and monomer. Examples of conditions include reaction temperature: not more than 100 ° C, preferably not less than 40 ° C and not more than 80 ° C, reaction time: 1 hour or more, preferably not less than 6 hours and not more than 30 hours, and stirring speed, not less than 50 rpm and not more than 500 rpm, preferably not less than 150 rpm and not more than 400 rpm.

In the process described above, in particular when the pseudo-fine dispersed particles of a polarizable polymer are prepared by polymerizing a monomer component containing at least one type of hydrophobic monomer and at least one type of hydrophilic monomer, the monomer component is preferably placed in an aqueous dispersion of a water-insoluble dye introduced in advance with an aqueous radical polymerization initiator. Or, conversely, the monomer component and the aqueous radical polymerization initiator are placed in an aqueous dispersion of a water-insoluble dye simultaneously or separately, which is also a preferred option. If the monomer mixture consists of various monomers, for example, hydrophobic monomers and hydrophilic monomers, it is preferable to keep the monomer copolymerization ratio at a constant level to uniformly obtain the desired pseudo-fine particles of a polarizable polymer. If the mixture of monomers is introduced into the polymerization system in excess of the amount consumed by the polymerization reaction in a certain period of time, a certain monomer can preferably polymerize, while leaving another that polymerizes after consuming the first monomer. In this case, the obtained pseudo-fine dispersed particles of the polarizable polymer can have significantly heterogeneous characteristics. Some of these particles, in particular those that contain most of the hydrophilic monomer component, may not adhere to the surface of the dye.

In addition, a polymer component containing a high proportion of the hydrophilic monomer component may not even stand out due to its high hydrophilicity, remaining as a water-soluble polymer component in the system without forming pseudo-fine particles of a polarizable polymer. On the other hand, the copolymerization ratio of the hydrophobic / hydrophilic monomer can be kept constant to uniformly obtain pseudo fine dispersed particles of the polarizable polymer at the desired copolymerization ratio if the monomer component is placed in an aqueous dispersion of a water-insoluble dye containing an aqueous radical polymerization initiator.

Some hydrophilic monomers, in particular anionic ones, for example acrylic acid and methacrylic acid, may become partially unstable with respect to agglomeration, depending on the characteristics of the polymer dispersant used to disperse the dye. The preferred embodiment of the present invention is the introduction of the anionic monomer in the form of a sodium or potassium salt after neutralization to avoid the above problems.

The above method of producing pseudo-finely dispersed particles of a polarizable polymer, attached to a water-insoluble dye, is preferably followed by a subsequent purification step to obtain aqueous ink containing the dye. To obtain a dispersible colorant with a high degree of storage stability over a long period of time, it is important to clean the mixture containing the unreacted polymerization initiator, the monomer component or dispersant, or the water-soluble polymer component or pseudo fine particles of the polarizable polymer that are not attached to the colorant. The purification step can be selected from the well-known. Cleaning by centrifugation or ultrafiltration is the preferred option.

A dispersible colorant with pseudo-fine dispersed particles of a polarizable polymer containing the desired copolymer attached to the surface of the colorant can be obtained using the above steps, since they allow good control of many regulatory parameters. If an anionic monomer is introduced in particular in order to obtain a high dispersion stability, the steps of the present invention provide a high density of surface functional groups and, thus, a high dispersion stability of a dispersible colorant, even if anionic monomer is used in relatively small amounts. Therefore, these stages can improve the stability of the dispersion of pseudo-finely dispersed particles of a polarizable polymer without compromising storage stability of the dispersible dye for a long period of time.

The authors of this invention suggest that improved dispersion stability of the dispersible dye is obtained as a result of the following mechanisms, which, however, are not fully confirmed. While pseudo-fine dispersed particles of a polarizable polymer are formed from oligomers released during the polymerization initiated by radicals formed in water, the oligomers constituting the component obtained from the anionic monomer in large quantities are preferably oriented towards the aqueous phase, i.e. proximity to pseudo-fine particles of a polarizable polymer. This condition persists after the pseudo-finely dispersed particles of the polarizable polymer are attached to the dye with a further concentration of the anionic group obtained from the anionic monomer component on the surface of the dispersible dye in accordance with this invention having a structure with a large specific surface area. As a result, the dispersible colorant obtained by the method in accordance with this invention can be stabilized with a small amount of anionic monomer component.

Water ink

Aqueous inks in accordance with this invention are characterized by the content of dispersible dye described above. If pigment is used for the dye, it is usually added in an amount of not less than 0.1% and not more than 20 wt.% With respect to the weight of the ink, preferably not less than 0.3% and not more than 15 wt.%. Preferably, the aqueous ink medium contains water or a water-soluble organic solvent, as necessary. A penetrating agent may be added to the ink to enhance their penetration into the recording substrate, preservative or antifungal agent.

The dispersible colorant of the present invention, which is present in the ink, contains pseudo fine dispersed particles of a polarizable polymer 2 attached to the surface of the colorant 1 (FIGS. 1A and 1B). Therefore, dye particles are attached to the recording substrate or to adjacent substrate particles using pseudo-fine dispersed particles of a polarizable polymer attached to its surface. Therefore, images obtained using aqueous ink in accordance with this invention must be very scratch resistant. One of the more preferred options is aqueous ink, which in addition to the above characteristics, incorporate self-dispersing finely dispersed polymer particles. This allows you to get very smooth images on a glossy substrate, which is usually difficult when using a conventional water-insoluble dye, such as pigment. More preferably, the ink contains pseudo-fine particles of a polarizable polymer (A) attached to a dye, and self-dispersible fine particles of a polymer (B) present in the ink, where the monomer component of particles (A) and the monomer component of particles (B) have at least one common monomer component. Such an ink composition provides highly improved image resistance to scratches on a glossy recording substrate, since particles (A) attached to the dye and particles (B) are more compatible with each other, which increases the stickiness of the ink.

The dispersible colorant in accordance with this invention has an average surface zeta potential of not less than -80 mV and not more than -20 mV in an aqueous medium that is part of aqueous ink, in particular if it contains an anionic group, and not less than +10 mV and not more than +60 mV if it contains a cationic group. This is also the preferred option. Aqueous inks can have excellent storage stability over a long period of time if the dispersible colorant included in them has a surface zeta potential within the above ranges. A dispersible colorant having a surface zeta potential of not less than -15 mV and not more than +10 mV may not have its inherent high dispersion stability when exposed to an aqueous medium, which gives water inks with insufficient dispersion stability for a long period of time. On the other hand, a dispersible colorant having a surface zeta potential of less than -80 mV and more than +60 mV can produce images having insufficient water resistance, although the ink will have excellent storage stability.

The term "zeta (ξ) potential", used in this description, sometimes called the "dynamic" potential at the phase boundary, means the potential obtained at the phase separation between a solid and a liquid in relative motion when they are in contact with each other. It is used to analyze the surface conditions of a solid present in a liquid. In the electric double layer obtained at the solid / liquid phase separation, the stationary phase (or adsorbed phase) is located on the side of the solid phase, where the stationary phase and the surface of the solid are charged by ions with opposite charges. When the solid and liquid are in relative motion, the stationary phase moves with the solid. Therefore, a potential arises between the surface of the stationary phase and the inner part of the solution, which actually controls the movement, and this potential is called the zeta potential. The zeta potential can be positive or negative depending on the charge of the stationary phase. If the water-insoluble colorant is stably dispersed in the ink, the colorant particles remain separated from each other and stably dispersed by the zeta potential of the colorant. Therefore, the zeta potential is a significant characteristic for dispersion stability and storage stability of inks containing water-insoluble inkjet dye.

In addition, the absolute value of the zeta potential in itself greatly affects the stability of the dispersion, and its distribution is also an important parameter. In a dispersion in which colloidal dispersions with different zeta potential are present, in particular, usually there is an attractive force between a dispersion with a higher potential and another dispersion with a lower potential with their agglomeration, even if they have the same sign (positive or negative) of the potential . This phenomenon is known as heteroagglomeration. In other words, a dispersible colorant in accordance with this invention, having a uniform absolute value of the zeta potential, affects the stabilization of dispersion in the ink in accordance with this invention. The inventors have found that the dispersible colorant of the invention exhibits the desired effect of stabilizing the dispersion if its zeta potential distribution is less than 50 with respect to the standard deviation within the mid-range.

The zeta potential varies depending on various conditions, for example, dielectric constant, pH and salt concentration in the aqueous medium in which the dye is present, and this is true for any other colloidal dispersion. Therefore, the zeta potential should be considered in relation to its absolute value and distribution, measured under certain conditions of the environment in which the dye is dispersed. The zeta potential of a dispersible colorant in aqueous ink can be determined by a conventional method. The zeta potential in this invention is determined on an analyzer (Microtech Nitchion ZEECOM), where an aqueous mixed solvent for aqueous ink, to which a dye is diluted in an appropriate ratio, is placed in a constant electric field to monitor the movement of the dispersed particles (dispersible dye in accordance with by this invention) and determining particle velocity by image processing.

However, it should be noted that the zeta potential may not be determined using the analysis method described above for inks containing a specific electrolyte in high concentration, even in an aqueous medium with the same composition, due to the very high electrical conductivity of the medium. In this case, the zeta potential of the dispersible colorant can be determined after processing the aqueous medium to obtain a pH corresponding to the level in the ink used, by removing or lowering the electrolyte to 0.01 M. The above ink actually contains a high concentration of electrolyte, and tends to decrease in storage stability. However, they can have improved storage stability by keeping the zeta potential of the dye within the limits of this invention.

If pigment is used as a dye, the preferred option is to introduce the pigment in a certain ratio with the polymer component of the pseudo fine dispersed particles of the polarizable polymer, or the polymer / pigment ratio (B / P ratio) of not less than 0.3 and not more than 4.0 for improved scratch resistance image obtained using aqueous ink. Maintaining a B / P ratio of at least 0.3 can improve the degree of attachment between the dye particles and between the dye particles and the recording substrate and, therefore, improve the scratch resistance of the image. In particular, aqueous ink containing a dispersible colorant may have more suitable film formation characteristics if the copolymer component of the pseudo fine dispersed particles of the polarizable polymer attached to the colorant has a glass transition temperature of at least -40 ° C and not more than 60 ° C, as described above, which also improves the scratch resistance of glossy paper. With a B / P ratio well above 4.0, the ink can be quite viscous and have poor ejection characteristics, in particular for inkjet recording devices. In addition, such inks may have insufficient image density, since a very high polymer content impairs the appearance of the color of the dye on the recording substrate. Keeping the B / P ratio in the above ranges of not less than 0.3 and not more than 4.0 allows you to get water inks, which at the same time have excellent scratch resistance and good ejection characteristics in inkjet recording devices. The polymer mass described above means the total number of pseudo-finely dispersed particles of the polarizable polymer and may include other polymer components that are strongly adsorbed on the surface of the pigment, however, it does not include a water-soluble polymer component that is easily separated from the pigment.

The B / P ratio can be determined by differential thermogravimetric analysis and determined on an analyzer (METTLER, TGA / SDTA851) in accordance with this invention. More specifically, the dispersible colorant of the invention or aqueous ink containing it, is ink-jet centrifuged at 80,000 rpm for 2 hours, dried, weighed and heated in a nitrogen atmosphere or in air to obtain a weight change of each of the pigment and polymer components before and after processing at the decomposition temperature, from which the ratio B / P is determined.

Recorded image

An image in accordance with this invention recorded on a substrate for recording using aqueous ink in accordance with this invention containing a dispersible dye with the above composition is obtained using an inkjet recording device described below. The recording substrate used in accordance with this invention is not limited, as long as it allows you to get an image on it using inkjet recording.

Dispersible dye in accordance with this invention, has the functions due to its characteristic forms shown in Figa, 7B and 7C, to obtain an inkjet image in accordance with this invention. Among these functions, those shown in Figs. 7B and 7C are more preferable, and they appear simultaneously during actual recording. The function shown in FIG. 7A occurs if the aqueous ink described above also contains finely dispersed particles of a self-dispersing polymer (B) to produce very smooth images on a recording substrate 14, where the pseudo-fine particles of a polarizable polymer or self-dispersing finely dispersed particles B are accumulated on substrate for smoothing irregularities between dye particles. In FIG. 7B, pseudo fine dispersed particles of a polarizable polymer 2 are present between adjacent dye particles and are simultaneously attached to these dye particles to provide a strong colored film for a recorded image with high scratch resistance. On Figs shows another preferred function, where the ratio of the surface of the dye to which the pseudo-fine dispersed particles of the polarizable polymer is attached, is partially reduced, which allows agglomeration of the dye particles, while realizing the function shown in Fig.7B. Fig. 7C illustrates the agglomeration of dye particles in ink, which form an image on a recording substrate, where the static repulsion between the pseudo-finely dispersed particles of the polarizable polymer (represented by arrow 15 in the figure) is balanced by the agglomeration force of the dye particles during the agglomeration, controlling the agglomeration. This control of agglomeration on the recording substrate allows you to control the density of the image and the spreading of ink.

A method of recording images and a recording device. The dispersible colorant and the aqueous ink containing it in accordance with this invention exhibit excellent performance when used in the head of an inkjet printing apparatus and when stored in an ink tank. Ink is also useful for filling ink. This invention demonstrates particularly excellent performance when used in a recording head and recorder according to the Bubble Jet® recording method.

The exemplary structure and operating principles are preferably based on the structure and basic principles described in US Pat. Nos. 4,723,129 and 4,740,796. This principle applies to the pulse type (“on request”) and to the continuous type. It is especially effective if applied in a pulsed type, where at least one signal supplied to the drive is transmitted to an electrothermal converter placed in a position corresponding to each of the sheets and channels for the liquid that hold the ink to quickly heat the ink to temperatures above the bubble boiling point, where the transducer generates enough heat to boil the film on the heated surface of the head for recording, which produces ink bubbles corresponding to their signal. Ink is ejected through the port for ejection under the influence of growing and expanding bubbles, with the formation of at least one drop. A pulsed signal is more preferable, as it can immediately and adequately cause the growth and expansion of bubbles to produce an ejection of ink with a high reaction. US Pat. Nos. 4,463,359 and 4,345,262 describe preferred pulsed signals. Recording can be made more efficiently under the conditions described in US patent No. 4313124, which describes the rate of temperature increase on the heated working surface of the head.

Preferred heads include a combination of ejection ports, fluid channels (linear or right-angled fluid channels), and electrothermal transducers as described in the aforementioned US patents. The invention is also effective in structures where the components are located on a corrugated heated work surface, as described in US Pat. Nos. 4,558,333 or 4,459,600. It is also effective in other structures with a plurality of 2 electrothermal converters having one or more common ink ejection ports, and native ports for ejecting ink, such as those described in Japanese Patent Application Laid-Open No. S59-123670. A “full-line” type recording head that covers a length corresponding to the maximum width over which the recording apparatus can record images may have a combination of a plurality of recording heads described in the above descriptions to cover a desired length, or may have such a structure, where they are assembled on one block. The present invention allows such types to demonstrate the above-described actions more efficiently.

The present invention is also effective if attached to a removable type recording head housing, in which it can be electrically connected to the ink supply body, and also to a cartridge into which it is mounted as an integral part on the recording head itself. The present invention can demonstrate its advantages more efficiently if it contains, as one of the components of the recording head, a reducing device or other auxiliary devices, which is another advantage in accordance with this invention. More specifically, these devices include nozzles, cleaning or sealing or inducing devices, an electric heat converter or other heating device, pre-heating devices including a combination of such devices, and a combination of such devices for a pre-ejection mode that is not used for recording.

Examples

The invention is described in more detail in the examples and comparative examples, which, however, do not limit the invention, in which variations can be made that are not beyond the scope of this invention. In the examples and comparative examples, “part (s)” and “%” are massive, unless otherwise indicated.

Example 1

Ink for recording 1 is obtained by the method described in example 1. First, a mixed solution having a composition of 10 parts of carbon black, 6 parts of glycerin, 10 parts of a styrene / acrylic acid dispersant and 74 parts of water is obtained as a pigment dispersion solution 1 by treating these components in a sand mill (Kaneda Scientific) with 0.6 mm diameter zirconia balls at 1500 rpm for 5 hours to disperse the pigment, where the container is filled at a filling rate of 70%. Soot is Black Pearls 880 (hereinafter referred to as BP880) obtained from Cabot Co., USA. The styrene / acrylic acid based dispersant has a copolymerization ratio of 70/30, a molecular weight (Mw) of 8000 and an acid number of 170. It is an aqueous solution obtained by mixing the dispersant with water and potassium hydroxide in an amount equivalent to the acid number at a temperature of 80 ° C. In the resulting pigment dispersion solution 1, pigment particles are stably dispersed having an average particle diameter of 98 nm in the dispersion and a polydispersity coefficient of 0.16.

Then, the mixed solution described below is slowly added dropwise into 100 parts of a pigment dispersion solution 1 with electric stirring at a temperature of 70 ° C. under a nitrogen atmosphere for polymerization, which lasts for 5 hours. The mixed solution contains 5.5 parts of methyl methacrylate, 0.5 parts of acrylic acid, 0.12 parts of potassium hydroxide, 0.05 parts of potassium persulfate and 20 parts of water. The resulting dispersion solution was diluted 10 times with water and centrifuged at 5000 rpm for 10 minutes to remove agglomerates. Then it is purified by centrifugation at 12500 rpm for 2 hours to obtain a precipitate in the form of a dispersible dye 1.

The dispersible colorant 1 is dispersed in water and purified by centrifugation at 12,000 rpm for 60 minutes. The resulting precipitate was redispersed in water and dried for analysis on a scanning electron microscope (JOEL Hightech, JSM-6700) at a magnification of 50,000. Analysis showed that dispersible dye 1 contains finely divided polymer particles attached to the carbon black surface. Dyes obtained in other examples are examined by the same procedure to confirm the dye morphology.

The composition below is added to dye 1 and filtered on a membrane filter (pore size: 2.5 μm) under pressure to obtain a recording ink containing dye 1 in an amount of 4%.

Glycerol 7 pieces Diethylene glycol 5 pieces Trimethylol propane 7 pieces Acetylenol EN (commercial Brand Name: Kawaken Fine Chemicals) 0.2 parts Ion exchange water balance

Example 2

The mixed solution described below is slowly added dropwise in 100 parts of a pigment dispersion solution 1 obtained in Example 1, with electric stirring at a temperature of 70 ° C. under a nitrogen atmosphere for polymerization, which lasts for 8 hours. The mixed solution contains 5.7 parts of styrene, 0.3 parts of acrylic acid, 0.07 parts of potassium hydroxide, 0.05 parts of potassium persulfate and 20 parts of water. The mixture after polymerization is purified by centrifugation according to the procedure of example 1 to obtain a dispersible dye 2. Ink for recording 2 containing dispersible dye 2 in the amount of 4%, obtained by the method of example 1.

Example 3

The mixed solution described below is slowly added dropwise in 100 parts of a pigment dispersion solution 1 obtained in Example 1, with electric stirring at a temperature of 70 ° C. under a nitrogen atmosphere for polymerization, which lasts for 6 hours. The mixed solution contains 5.7 parts of methyl methacrylate, 0.3 parts of acrylic acid, 0.07 parts of potassium hydroxide, 0.05 parts of potassium persulfate and 20 parts of water. The mixture after polymerization is purified by centrifugation according to the method of example 1 to obtain a dispersible dye 3.

The polymerization is carried out according to the procedure of example 1 except that 100 parts of the solution of the dispersion of pigment 1 is replaced by 100 parts of a 2% aqueous solution of potassium hydroxide, in an amount equivalent to the styrene / acrylic acid dispersant used in example 1, and the polymerization mixture is centrifuged according to the method example 1, except that apply 20,000 rpm for 1 hour, to obtain finely dispersed particles of polymer B1.

Ink for recording 3 containing dispersible dye 3 and finely dispersed particles of polymer B1 in an amount of 4% and 1.2%, respectively, was obtained by the method of example 1.

Example 4

The mixed solution described below is slowly added dropwise in 100 parts of a pigment dispersion solution 1 obtained in Example 1, with electric stirring at a temperature of 70 ° C. under a nitrogen atmosphere for polymerization, which lasts for 6 hours. The mixed solution contains 4.5 parts of benzyl methacrylate, 1.2 parts of butyl acrylate, 0.3 parts of acrylic acid, 0.07 parts of potassium hydroxide, 0.05 parts of potassium persulfate and 20 parts of water. The mixture after polymerization is purified by centrifugation according to the method of example 1 to obtain a dispersible dye 4.

Dispersible dye 4 is analyzed according to the method of example 1. The analysis confirms that the dye also contains finely dispersed particles attached to the surface of the carbon black, but more condensed than in the dye obtained in example 1.

The polymerization is carried out according to the method of example 3 to obtain finely dispersed particles of polymer B1, replacing 100 parts of a solution of the dispersion of pigment 1 from example 1, to obtain finely dispersed particles of polymer B2. Ink for recording 4, containing dispersible dye 4 and finely dispersed particles of polymer B2 in the amount of 4% and 1.2%, respectively, was obtained by the method of example 1.

Example 5

The mixed solution described below is slowly added dropwise in 100 parts of a pigment dispersion solution 1 obtained in Example 1, with electric stirring at a temperature of 50 ° C. under a nitrogen atmosphere for polymerization, which lasts for 5 hours. The mixed solution contains 6 parts of butyl acrylate, 0.05 parts of potassium persulfate, the same number of moles of sodium thiosulfate as potassium persulfate, and 20 parts of water. The mixture after polymerization is purified by centrifugation according to the method of example 1 to obtain a dispersible dye 5.

Dispersible dye 5 is analyzed according to the method of example 1. The analysis confirms that the dye also contains finely dispersed particles attached to the surface of the carbon black, but more condensed than in the dye obtained in example 1. Ink for recording 5 containing dispersible dye 5 in an amount of 4% receive according to the method of example 1.

Example 6

The mixed solution described below is slowly added dropwise into 100 parts of a pigment dispersion solution 1 obtained in Example 1, with electric stirring at a temperature of 70 ° C. under a nitrogen atmosphere for polymerization, which lasts for 5 hours. The mixed solution contains 17.2 parts of methyl methacrylate, 0.8 parts of sodium p-styrene sulfonate, 0.05 parts of potassium persulfate and 20 parts of water. The mixture after polymerization is purified by centrifugation according to the procedure of Example 1 to obtain a dispersible colorant 6. Ink for recording 6 containing dispersible colorant 6 in an amount of 4% is obtained according to the procedure of Example 1.

Example 7

Ink for recording 7 is obtained by the method described in example 7. First, a mixed solution having a composition of 10 parts of carbon black, 6 parts of glycerol, 10 parts of a styrene / dimethylaminoethyl acrylate copolymer dispersant and 74 parts of water is obtained as a pigment dispersion solution 2 by treating these components in a sand mill (Kaneda Scientific Co.) with 0.6 mm diameter zirconia balls at 1500 rpm for 5 hours to disperse the pigment, where the container is filled at a filling rate of 70%. Soot is the same as in example 1 (BP880). The styrene / dimethylaminoethyl acrylate copolymer dispersant has a copolymerization ratio of 70/30, a molecular weight (Mw) of 8000 and an amine number of 170. It is an aqueous solution obtained by mixing the dispersant with water and acetic acid in an amount slightly higher than the amine number above at a temperature of 80 ° C. The resulting solution of the dispersion of pigment 2 is stably dispersed with pigment particles having an average particle diameter in the dispersion of 105 nm and a polydispersity coefficient of 0.18.

Then, the mixed solution described below is slowly added dropwise into 90 parts of a pigment dispersion solution 2 with electric stirring at a temperature of 55 ° C. under a nitrogen atmosphere for polymerization, which lasts for 7 hours. The mixed solution contains 4.2 parts of benzyl methacrylate, 1.8 parts of dimethylaminoethyl acrylate, 0.3 parts of V-50 (Wako Pure Chemical Industries) and 20 parts of water. The resulting dispersion solution was diluted 10 times with water and centrifuged at 5000 rpm for 10 minutes to remove agglomerates. Then it is purified by centrifugation at 12500 rpm for 2 hours to obtain a precipitate in the form of a dispersible dye 7. Get ink for recording 1 containing dye 7 in an amount of 4%, where dye 7 is filtered and combined with the composition according to the method of example 1.

Example 8

Ink for recording 8 is obtained by the method described in example 8. First, a mixed solution having a composition of 10 parts of a blue pigment (PB) 15:13 (Clariant Co.) as a dye, 6 parts of glycerol, 10 parts of a styrene / acrylic acid dispersant and 74 parts of water, are obtained as a pigment dispersion solution 3 by treating these components in a sand mill (Kaneda Scientific Co.) with 0.6 mm diameter zirconia balls at 1500 rpm for 5 hours to disperse the pigment, where capacity is filled with a filling rate of 70%. The styrene / acrylic acid based dispersant has a copolymerization ratio of 70/30, a molecular weight (Mw) of 8000 and an acid number of 170. The resulting pigment dispersion solution 3 is stably dispersed with pigment particles having an average particle diameter of 108 nm and a polydispersity coefficient of 0.14 .

Then, the mixed solution described below is slowly added dropwise into 100 parts of a pigment dispersion solution 3 with electric stirring at a temperature of 70 ° C. under a nitrogen atmosphere for polymerization, which lasts for 5 hours. The mixed solution contains 5.7 parts of methyl methacrylate, 0.3 parts of acrylic acid, 0.07 parts of potassium hydroxide, 0.05 parts of potassium persulfate and 20 parts of water. The resulting dispersion solution was diluted 10 times with water and centrifuged at 5000 rpm for 10 minutes to remove agglomerates. Then it is purified by centrifugation at 12,500 rpm for 2 hours to obtain a precipitate in the form of a dispersible dye 8. Get ink for recording 8 containing dye 8 in an amount of 3.5%, where dye 8 is filtered and combined with the composition according to the method of example 1 .

Example 9

Ink for recording 9 is obtained by the method described in example 9. First, a mixed solution having a composition of 10 parts of a yellow pigment (PY) 180 (Clariant Co.) as a dye, 6 parts of glycerol, 10 parts of a styrene / acrylic acid dispersant and 74 parts of water are obtained in the form of a pigment dispersion solution 4 by treating these components in a sand mill (Kaneda Scientific) with 0.6 mm diameter zirconia balls at 1500 rpm for 5 hours to disperse the pigment, where the container is filled at a speed filling 70%. The styrene / acrylic acid based dispersant has a copolymerization ratio of 70/30, a molecular weight (Mw) of 8000 and an acid number of 170. The resulting pigment dispersion solution 4 is stably dispersed with pigment particles having an average particle diameter of 126 nm and a polydispersity coefficient of 0.16 .

Then, the mixed solution described below is slowly added dropwise into 100 parts of a pigment dispersion solution 4 with electric stirring at a temperature of 70 ° C. under a nitrogen atmosphere for polymerization, which lasts for 5 hours. The mixed solution contains 5.7 parts of methyl methacrylate, 0.3 parts of acrylic acid, 0.07 parts of potassium hydroxide, 0.05 parts of potassium persulfate and 20 parts of water. The resulting dispersion solution was diluted 10 times with water and centrifuged at 5000 rpm for 10 minutes to remove agglomerates. Then it is purified by centrifugation at 12500 rpm for 2 hours to obtain a precipitate in the form of a dispersible dye 9.

Receive ink for recording 9 containing dye 9 in an amount of 3.5%, where dye 9 is filtered and combined with the composition according to the method of example 1.

Example 10

Ink for recording 10 is obtained by the method described in example 10. First, a mixed solution is obtained having a composition of 10 parts of red pigment (PR) 122 (Ciba Specialty Chemicals Co.) as a dye, 6 parts of glycerol, 10 parts of a styrene dispersant / acrylic acid and 74 parts of water, in the form of a pigment dispersion solution 5, by treating these components in a sand mill (Kaneda Scientific) with 0.6 mm diameter zirconia balls at 1500 rpm for 5 hours to disperse the pigment, where the capacity filled with a filling rate of 70%. The styrene / acrylic acid based dispersant has a copolymerization ratio of 70/30, a molecular weight (Mw) of 8000 and an acid number of 170. The resulting pigment dispersion solution 5 is stably dispersed with pigment particles having an average particle diameter of 96 nm and a polydispersity coefficient of 0.13 .

Then, the mixed solution described below is slowly added dropwise into 100 parts of a pigment dispersion solution 5 with electric stirring at a temperature of 70 ° C. under a nitrogen atmosphere for polymerization, which lasts for 5 hours. The mixed solution contains 5.7 parts of methyl methacrylate, 0.3 parts of acrylic acid, 0.07 parts of potassium hydroxide, 0.05 parts of VA-057 (Wako Pure Chemical Industries) and 20 parts of water. The resulting dispersion solution was diluted 10 times with water and centrifuged at 5000 rpm for 10 minutes to remove agglomerates. Then it is purified by centrifugation at 12500 rpm for 2 hours to obtain a precipitate in the form of a dispersible dye 10.

Receive ink for recording 10 containing dye 10 in an amount of 3.5%, where dye 10 is filtered and combined with the composition according to the method of example 1.

Dispersible Dye Characteristics

Dispersible dyes obtained in examples 1-10 are analyzed by the methods described below to determine their properties. The results are given in table 1.

Fixation and presence of finely dispersed polymer particles.

Each dispersible dye is dispersed in water and dried for analysis on a scanning electron microscope (JOEL Hightech, JSM-6700) at a magnification of 50,000. The state and characteristics of the finely dispersed particles attached to the dye are evaluated according to the following standards:

Attachment state of finely dispersed polymer particles to a dye O: attachment of finely dispersed polymer particles to a dye is confirmed.

x: the attachment of finely dispersed polymer particles to the dye is not confirmed.

The presence of finely dispersed polymer particles.

A: finely dispersed polymer particles are uniformly distributed.

x: finely dispersed polymer particles are distributed unevenly or attached unevenly to the dye.

Dispersion stability.

A 5% aqueous dispersion of each dye is diluted ten times with pure water and concentrated to the initial concentration on an ultrafilter trapping a molecular weight of 50,000. The concentrated solution is centrifuged at 12,000 rpm for 2 hours, and the resulting precipitate is collected and redispersed in pure water. The dye is visually evaluated for uniformity of particle distribution and analyzed by dynamic light scattering to confirm that the particle diameter is 2 times or less larger than the original diameter before processing. Assessment is carried out according to the following standards.

A: The above conditions are satisfied.

x: the above conditions are not satisfied.

Storage stability over a long period of time.

Storage stability over a long period of time is evaluated visually after placing the aqueous dispersion of each dye in a closed glass bottle and standing at a temperature of 60 ° C for 1 month. Assessment is carried out according to the following standards.

A: no agglomeration or precipitation of solids.

B: solids deposition to a small extent, but the solution returns to its original dispersed state with gentle shaking.

C: agglomeration or precipitation of solids takes place, and the solution does not return to its original dispersed state with gentle shaking.

The average particle size.

Each dispersed dye is analyzed by dynamic light scattering (analyzer: Otsuka Electronics ELS-8000), and the average particle diameter is presented as a cumulative average value.

Glass transition temperature: Tg (° C)

The glass transition temperature of the finely dispersed polymer particles attached to the dye is analyzed on an analyzer (METTLER-TOLEDO's DSC822e), where the dried sample of the dispersible dye is heated at a rate of 0.5 ° C / minute.

Density of surface functional groups

The density of the surface functional groups of each dispersible dye is determined by the following method. The aqueous dispersion of the dispersible colorant is diluted with excess hydrochloric acid (HCl) and centrifuged at 20,000 rpm for 1 hour. The precipitate obtained is redispersed in pure water and its solids content is determined. The redispersed precipitate was weighed and then combined with a known amount of sodium bicarbonate and stirred, then centrifuged at 80,000 rpm for 2 hours. The supernatant is weighed and titrated with 0.1 N hydrochloric acid before neutralization to determine the density of surface functional groups by subtracting the known amount of sodium bicarbonate and the value for pure water from the amount to neutralize. If the dispersible colorant contains a cationic group as a polar group, the density of the surface functional groups is determined by the same procedure, except that sodium hydroxide (NaOH) and ammonium chloride are used instead of hydrochloric acid and sodium bicarbonate, respectively.

Surface energy

The dried and ground dispersible colorant is placed in a column and analyzed using a Surfase Measurement System, in which hexane, heptane, pentane, chloroform, ethanol or acetone are used as a sample gas. Surface energy is determined by extrapolating the dispersion dye gas retention time for each sample gas. The ink composition and evaluation results obtained in Examples 1-8 are shown in Table 1, where MMA: methyl methacrylate, AAc: acrylic acid, St: styrene, BzMA: benzyl methacrylate, VA: butyl acrylate, NaSS: sodium p-styrene sulfonate, DMAEA: dimethylaminoethyl acrylate KPS: potassium persulfate; and NaTS: sodium thiosulfate.

Methods for evaluating water-based ink for inkjet recording and evaluation results.

Ink characteristics are evaluated using the following methods. Using each ink, images are obtained on a recording substrate using an inkjet recording device (Canon's BJ S600) and evaluated. The image is evaluated for optical density (OD), sharpness, scratch resistance, marker resistance, storage stability at ordinary temperature and ejection stability. The results are shown in table 2.

The mass ratio of polymer / pigment (ratio B / P).

The B / P ratio is analyzed by differential thermogravimetric analysis (METTLER-TOLEDO, TGA / SDTA851) and calculated for dried ink.

Zeta (ξ) surface potential.

The dispersible dye obtained in each example is diluted about 100,000 times in the aqueous solvent used in Example 1, which does not contain a dispersible dye and finely dispersed polymer particles, and ξ the fixed surface potential of the cells is measured on an analyzer (Microtech Nitchion ZEECOM) for 100 particles. The average potential and standard deviation for 100 particles are recorded.

Optical Density (OD)

Optical density (OD) is determined for a black text image recorded using each ink for recording on Canon's PPC paper and left for 1 day. Ink is evaluated according to the following standards, with the exception of the ink obtained in Example 8, in which OD is estimated as cyan instead of black OD, and is designated “A” if not less than 1.0.

A: OD images of at least 1.3.

B: OD images of at least 0.8 and less than 1.3.

C: OD images less than 0.8.

Scratch resistant.

The image is scratched 5 times with a carbon paper to which a pressure of 40 g / cm ² is applied to visually assess the damage to the image and evaluated according to the following standards.

A: Scratching does not damage the image or leave paint on an empty part.

Q: Scratching damages the image or leaves paint on an empty part, but not on a significant scale.

C: Scratching significantly damages the image or leaves paint on an empty part.

Marker Resistance.

Stripes are applied onto the image with a fluorescent yellow marker (ZEBRA's OPTEX) to visually assess image damage, and evaluated according to the following standards.

A: Applying stripes does not damage the image.

Q: Applying stripes damages the image on a limited scale, slight staining of the marker rod.

C: Applying stripes damages significantly the image, staining of the marker rod.

Storage stability over a long period of time.

Storage stability over a long period of time is evaluated visually after each ink sample is placed in a closed glass bottle and left to stand at room temperature for 1 month. It is evaluated according to the following standards.

A: Agglomeration or precipitation of solids is not observed.

Q: A slight precipitation of solids occurs, but the ink returns to its original dispersed state with a slight shaking.

C: Agglomeration or precipitation of solids takes place, and the ink does not return to its original dispersed state with slight shaking.

Ejection stability.

Specific black text is recorded on 100 sheets to assess the stability of the ejection by visual inspection of the first and last pages according to the following standards.

A: Lines, image unevenness or similar phenomena are not observed, there are no differences between the images on the first and last pages.

B: the image is obtained without problems, although one or more lines, image unevenness or image distortion are slightly present.

C: Image is significantly degraded or printing is not possible.

The dispersible colorant obtained in each of examples 1-10 gives good results, which proves its dispersion stability, as shown in table 1. The recording ink obtained in each example also exhibits excellent recording characteristics, although the ink obtained in example 5 containing dispersible dye 5, have a lower density of surface functional groups and lower L, the potential is slightly lower than that of other inks when evaluating storage stability over a long period of time and stability ejection emission, as shown in table 2. From the point of view of scratch resistance, the recording ink obtained in example 3 containing finely dispersed particles of self-dispersing polymer B, exhibit higher stability compared to ink for recording 1, although the dispersible dye is synthesized from the same monomers for these dyes.

Table 1
The properties of dispersible dyes 1-10 and the results of their assessment dispersible colorant 1 dispersible colorant 2 dispersible dye 3 dispersible dye 4 dispersible colorant 5 dispersible dye 6 dispersible dye 7 dispersible colorant 8 dispersible dye 9 the disperser
curable dye 10 dye BP880 BP880 BP880 BP880 BP880 BP880 BP880 PB15: 3 PY180 PR122 acid number
dispersant 170 170 170 170 170 170 kyationny (Yamino number 170) 170 170 170 and similar monomers MMA AAAs St ae MMA AAAs BzMA VA AAs VA MMA NaSS BzMA DMAEA MMA AAAs MMA
AAA MMA
AAA degree of charge of monomers 5.5 0.5 5.7 0.3 5.7 0.3 4.5 1.2 0.3 6 17.2 0.8 4.2 1.8 5.7
0.3 5.7 0.3 5.7
0.3 total monomer content 6 6 6 6 6 eighteen 6 6 6 6 initiator
polymerization KPS KPS KPS KPS KPS / NaTS KPS V-50 KPS KPS VA-057 results 0 about about 0 0 0 0 0 0 0 the presence of finely dispersed polymer particles 0 about about 0 about 0 0 0 0 0 dispersion stability 0 about about 0 about 0 0 0 0 0 average diameter of dispersed seeded particles (km) 126 118 123 134 121 135 130 121 141 101 Tg [° C] 105 110 105 thirty -fifteen 115 95 105 105 105 density
surface functional groups (μmol / g) 370 290 342 321 87 274 272 286 292 261 surface energy
(mJ / m ² ) 45.8 40,2 45,2 32,7 22.5 46.5 38.5 43.7 46.8 44.1 long-term storage stability BUT BUT BUT BUT AT BUT BUT BUT BUT BUT

MMA: methyl methacrylate, AAA: acrylic acid, St: styrene

BzMA: benzyl methacrylate, VA: butyl acrylate, NaTS: sodium thiosulfate

NaSS: sodium p-styrenesulfonate

DMAEA: dimethylaminoethyl acrylate

table 2 Record Ink Properties 1-10 and Evaluation Results
their recording characteristics ink for writing 1 writing ink 2 ink
for recording 3 ink for writing 4 writing ink 5 recording ink 6 ink for writing
7 ink for writing 8 writing ink 9 writing ink 10 dispersible colorant one 2 3 four 5 6 7 8 9 10 starting momomers MMA AAAs St
AAA MMA
AAA BzMA VA AAs VA MMA NaSS BzMA DMAEA MMA
AAA MMA
AAA MMA
AAA the presence of finely dispersed polymer particles 0 0 0 0 0 0 0 0 0 0 finely dispersed MMA Bzma
DA polymer particles B AAA AAA Tg [° C] 105 110 105 thirty -fifteen 115 95 105 105 105 polymer / pigment ratio (B / P ratio) 0.2 0.2 0.5 0.5 0.4 0.8 0.4 0.3 0.4 0.3 ξ potential [mV] -thirty -25 -28 -26 -12 -31 eighteen 28 thirty -26 standard deviation
ξ 35 37 35 38 25 33 42 32 28 25 of capacity superficial energy
(mJ / m ² ) 45.8 40,2 45,2 32,7 22.5 46.5 38.5 43.7 46.8 44.1 optical image density (OD) BUT BUT BUT BUT BUT BUT BUT BUT BUT BUT Scratch resistant AT AT BUT BUT BUT BUT BUT BUT BUT BUT Marker Resistance BUT BUT BUT BUT BUT BUT BUT BUT BUT BUT storage stability during
long period
time BUT BUT BUT BUT AT BUT BUT BUT BUT BUT emission stability BUT BUT BUT BUT AT BUT AT BUT BUT BUT

MMA: methyl methacrylate, AAA: acrylic acid, St: styrene

BzMA: benzyl methacrylate, VA: butyl acrylate

NaSS: sodium p-styrenesulfonate

DMAEA: dimethylaminoethyl acrylate

Example 11

The mixed solution described below is slowly added dropwise into 100 parts of a pigment dispersion solution 1 obtained in Example 1, with electric stirring at a temperature of 70 ° C. under a nitrogen atmosphere for polymerization, which lasts for 5 hours. The mixed solution contains 4.28 parts of styrene, 1.42 parts of hydroxyethyl methacrylate, 0.3 parts of acrylic acid, 0.07 parts of potassium hydroxide, 0.05 parts of potassium persulfate and 20 parts of water. The resulting dispersion was diluted 10 times with water, and centrifuged at 5000 rpm for 10 minutes to remove agglomerates. Then it is purified by centrifugation at 12,500 rpm for 2 hours to obtain a dispersible dye 11. Ink for recording 11 containing dispersible dye 11 in an amount of 4% is obtained by filtering dye 11 and combining it with the composition according to the procedure of Example 1.

Example 12

The mixed solution described below is slowly added dropwise into 100 parts of a pigment dispersion solution 1 obtained in Example 1, with electric stirring at a temperature of 70 ° C. under a nitrogen atmosphere for polymerization, which lasts for 5 hours. The mixed solution contains 45.6 parts of ethyl methacrylate, 2.4 parts of acrylic acid, 0.6 parts of potassium hydroxide, 0.1 parts of potassium persulfate and 20 parts of water. The resulting polymerization mixture was purified by centrifugation as described in Example 9 to obtain a dispersible colorant 12. Ink for recording 12 containing 4% dispersible colorant 12 was obtained by filtering the colorant 12 and combining it with the composition as described in Example 1.

Example 13

The mixed solution described below is slowly added dropwise into 100 parts of a pigment dispersion solution 1 obtained in Example 1, with electric stirring at a temperature of 70 ° C. under a nitrogen atmosphere for polymerization, which lasts for 5 hours. The mixed solution contains 5.7 parts of benzyl methacrylate, 0.3 parts of methacrylic acid, 0.07 parts of potassium hydroxide, 0.01 parts of potassium persulfate and 20 parts of water. The resulting polymerization mixture was purified by centrifugation according to the procedure of Example 1 to obtain dispersible dye 13 as a precipitate. Ink for recording 13 containing dispersible dye 13 in an amount of 4% is obtained by filtering dye 13 and combining it with the composition according to the procedure of Example 1.

Example 14

The mixed solution described below is slowly added dropwise in 100 parts of a pigment dispersion solution 1 obtained in Example 1, with electric stirring at a temperature of 70 ° C. under a nitrogen atmosphere for polymerization, which lasts for 7 hours. The mixed solution contains 10 parts of methyl methacrylate, 8 parts of acrylic acid, 1.9 parts of potassium hydroxide, 0.05 parts of potassium persulfate and 20 parts of water. The resulting polymerization mixture was purified by centrifugation according to the procedure of Example 1 to obtain a dispersible colorant 14. Ink for recording 14 containing 4% dispersible colorant 14 was obtained by filtering the colorant 14 and combining it with the composition according to the procedure of Example 1.

Example 15

The mixed solution described below is slowly added dropwise into 100 parts of a pigment dispersion solution 1 obtained in Example 1, with electric stirring at a temperature of 70 ° C. under a nitrogen atmosphere for polymerization, which lasts for 5 hours. The mixed solution contains 4.5 parts of benzyl methacrylate, 1.2 parts of butyl acrylate, 0.3 parts of acrylic acid, 0.07 parts of potassium hydroxide, 0.05 parts of potassium persulfate and 20 parts of water. The resulting mixture for polymerization is purified by centrifugation according to the method of example 1 to obtain a dispersible dye 15.

The polymerization is carried out according to the method of example 1, except that 100 parts of the solution of the dispersion of pigment 1 is replaced by 100 parts of a 2% aqueous solution of potassium hydroxide in an amount equivalent to the amount of the styrene / acrylic acid dispersant used in example 1, the polymerization mixture is purified according to the method of example 1, except that it is carried out at 20,000 rpm for 1 hour, to obtain finely dispersed particles of polymer B3.

Ink for recording 15, containing dispersible dye 15 and finely dispersed particles of polymer B3 in the amount of 4% and 19.2%, respectively, was obtained by the method of example 1.

Ink properties to record their assessment

results

The dispersible dye obtained in each of examples 11-15 is evaluated using different methods and its properties are analyzed according to the analysis method of examples 1-10. The results are given in table 3, where St: styrene, NEMA: hydroxyethyl methacrylate, AAA: acrylic acid, EMA: ethyl methacrylate, MAC: methacrylic acid, BzMA: benzyl methacrylate, MMA: methyl methacrylate, VA: butyl acrylate and KPS: potassium persulfate.

The recording characteristics of the recording ink obtained in Examples 11-15 are also evaluated by the parameters used for the samples obtained in Examples 1-10. In addition, the following additional recording characteristics are evaluated.

The ability to dry quickly.

The image is obtained using each ink according to the method of examples 1-10 and scratch with a finger one minute after the recording is completed, to evaluate staining according to the following standards.

A: No staining is observed on the empty part.

Q: The empty part is slightly colored, but there are no problems with recognizing letters.

C: The letters are blurry and the empty part is clearly colored.

Resistant to water.

The recording substrate, on which a black text image is applied according to the methods of examples 1-10, is tilted at an angle of 45 ° horizontally with the image facing up, 1 ml of water is dripped onto it from a height of 20 cm using a syringe and the smudges of the image are observed. Resistance to water is evaluated according to the following standards.

A: Image spreading is practically absent.

Q: There is a slight spreading of the image, but no traces of it are visible on the empty part.

C: The dye drains from the image and leaves traces on an empty part.

The results are given in table 4.

Table 4 summarizes the composition, properties and grades of the ink obtained in each example 11-15.

As shown in table 4, good results were achieved for all inks, which confirms the content of self-dispersible dye in them. However, the ink obtained in Example 13 contains polymer particles agglomerated with the pigment surface to a greater extent and less uniformly distributed. All recording inks exhibit superior recording performance. However, the ink obtained in example 11, having a higher surface energy, is slightly worse than the rest in terms of speed of drying and resistance to water. The ink obtained in example 13, containing finely dispersed particles of the polymer, is distributed less uniformly compared to others, and slightly worse than others in image density, ability to dry quickly and ejection stability. The ink obtained in example 14 has a higher density of functional surface groups and is slightly worse than others in marker resistance and, more notably, in water resistance, although they have sufficient image density and ejection stability. On the other hand, the ink obtained in Example 15 has a higher B / P ratio compared to others and is slightly worse than others in ejection stability, as they sometimes produce curved images during the initial ejection stage and high-speed printing, which is presumably from - due to the increased viscosity of the ink, which worsens the response to high-speed ejection.

Table 3
Compositions and properties of dispersible dyes 11-15 the results of their evaluation. dispersible dye 11 dispersible dye 12 dispersible dye 13 dispersible dye 14 dispersible dye 15 dye BP880 BP880 BP880 BP880 BP880 dispersant acid number 170 170 170 170 170 raw materials St
NEMA
AAc Ema
MAc Bzma
AAc MMA
AAc Bzma
VA
AAc degree of charge of monomers 4.28
1.42
0.3 45.6
2,4 5.7
0.3 10
8 4,5
1,2
0.3 total monomer content 6 48 6 eighteen 6 polymerization initiator KPS KPS KPS KPS KPS results 0 0 0 0 0 the presence of finely dispersed polymer particles 0 0 X 0 0 dispersion stability 0 0 0 0 0 finely dispersed polymer B particles - - - - Bzma
VA
AAc average diameter
dispersed
particles (nm) 122 170 320 152 134 Tg [° C] 60 45 108 102 thirty surface functional density
groups (μmol / g) 275 302 180 1086 321 surface energy (mJ / m ² ) 82.7 47.2 45.5 92.5 32,7 storage stability during
long period of time BUT BUT BUT BUT BUT

St: styrene, NEMA: hydroxyethyl methacrylate, AAc: acrylic acid

EMA: ethyl methacrylate, MAc: methacrylic acid, BzMA:

benzyl methacrylate

MMA: methyl methacrylate, VA: butyl acrylate

Table 4
Properties of ink for writing 11-15 and the results of their assessment
recording characteristics writing ink 11 12 ink recording ink 13 recording ink 14 recording ink 15 dispersible
dye eleven 12 13 fourteen fifteen starting monomers St
NEMA
AAc Ema
MAc Bzma
AAc MMA
AAc Bzma
VA
AAc finely dispersed particles of polymer b - - - - Bzma
VA
AAc finely dispersed
polymer particles 0 0 × 0 0 Tg [° C] 60 45 108 102 thirty polymer / pigment ratio (B / P ratio) 0.3 1,5 1,2 0.4 5.1 ξ
potential [mV] -27 -26 -27 -90 -26 standard deviation
ξ
of capacity 33 32 72 45 38 density of surface functional groups (μmol / g) 275 302 180 1086 321 surface energy (mJ / m ² ) 82.7 47.2 45.5 92.5 32,7 optical image density (OD) BUT BUT AT BUT AT Scratch resistant BUT BUT BUT AT BUT Marker Resistance BUT BUT BUT AT BUT long-term storage stability BUT BUT AT BUT AT quick drying ability AT BUT AT BUT BUT water resistance BUT BUT BUT FROM BUT emission stability BUT BUT AT BUT FROM

St: styrene, NEMA: hydroxyethyl methacrylate, AAc: acrylic acid

EMA: ethyl methacrylate, MAc: methacrylic acid, BzMA: benzyl methacrylate

MMA: methyl methacrylate, VA: butyl acrylate

Comparative Example 1

Comparative ink 1 containing pigment in an amount of 4% is obtained according to the procedure of Example 1; dispersion solution 1 obtained in Example 1 is used for the pigment. Comparative ink 1 obtained according to the procedure of Example 1 does not contain finely dispersed polymer particles attached to the dye.

Reference Example 2

Comparative ink 2 is prepared according to the procedure of Example 1, except that the surface treated self-dispersing carbon black (Cabot's Cabojet 200) is contained in an amount of 4% of the solids content, and the finely dispersed particles of polymer B1 obtained in Example 3 are contained in an amount of 1.6 % Comparative ink 2 obtained by the method of example 1, contain a finely dispersed particle of polymer attached to the dye in places. However, the fixation distribution of such particles is not uniform, and there is some agglomeration with each other.

The dyes obtained in each of comparative examples 1 and 2 are examined using various methods and their properties are analyzed according to the methods of examples 1-15. The results are given in table 5. Ink for recording, obtained in each of comparative examples 1 and 2, evaluated by the methods of examples 9-15. The results are given in table 6.

The dyes obtained in each of comparative examples 1 and 2 are examined using various methods and their properties are analyzed according to the methods of examples 1-13. The results are given in table 5. Ink for recording, obtained in each of comparative examples 1 and 2, evaluated by the methods of examples 9-13. The results are given in table 6.

It is obvious that the ink obtained in each of comparative examples 1 or 2 is significantly worse than the ink in accordance with this invention obtained in each example, in particular, in image density, storage stability over a long period of time, and ejection stability . The ink obtained in comparative example 2 is significantly worse than the ink in accordance with this invention in scratch resistance, resistance to water and the ability to quickly dry, since the dye, although it is self-dispersing, does not contain finely dispersed particles attached to it sufficiently .

Table 5
Properties of the dyes obtained in comparative examples 1 and 2 and the results of their evaluation. comparative example 1 comparative example 2 dye BP880 Cababoet200 dispersant acid number 170 - results X X the presence of finely dispersed polymer particles - - dispersion stability X 0 finely dispersed particles of polymer b - MMA
AAA the average diameter of the dispersed particles (nm) 98 102 Tg [° C] - 105 density of surface functional groups (μmol / g) - 270 surface energy (mJ / m ² ) - - long-term storage stability FROM FROM

MMA: methyl methacrylate and AAA: acrylic acid

Table 6
Properties of ink for writing obtained in comparative
examples 1 and 2, and the results of the assessment of their recording characteristics comparative ink 1 comparative ink 2 dye comparative example 1 comparative example 2 results x x the presence of finely dispersed polymer particles - - finely dispersed particles of polymer b - MMA
AAA Tg [° C] - 105 polymer / pigment ratio (B / P ratio) - 0.4 ξ, potential [mV] - -25 standard deviation of ξ, potential - 37 density of surface functional groups (μmol / g) 270 surface energy (mJ / m ² ) - - optical image density (OD) FROM FROM scratch resistant AT AT marker resistance AT FROM storage stability during
long period of time FROM FROM quick drying ability AT FROM water resistance FROM FROM emission stability FROM FROM

MMA: methyl methacrylate and AAA: acrylic acid

In addition, the ink for recording obtained in examples 1-4, 6, 12 and 15 was further evaluated using the following methods, and the results are presented in table 7. Solid streaks (5 square cm) are applied using black ink obtained in each of examples on glossy inkjet paper (Canon's PR-101) using a recording device and conduct the above studies to evaluate image density, scratch resistance and gloss on glossy paper.

Image density on glossy paper.

The image is examined one day after application to determine the optical density (OD) and evaluated according to the following standards.

A: OD images of at least 2, 3.

B: OD images of 1, 7 or more and less than 2, 3.

C: OD images less than 1, 7.

Scratch resistant on glossy paper.

The image is scratched 5 times with a carbon paper to which a pressure of 40 g / cm ² is applied to visually assess the damage to the image and evaluated according to the following standards.

A: Scratching slightly damages the image and leaves virtually no paint on the empty part.

Q: The image is damaged, but at least 90% of the printed image remains.

C: Image is significantly damaged.

Gloss image

Visually evaluate the gloss of the image according to the following standards.

A: The image is glossy in almost the same degree as the clean part.

Q: The image is quite glossy, although it shows a greater irregular reflection compared to the clean part.

C: The image is not glossy and practically does not reflect light.

The ink obtained in example 2 containing styrene and obtained in example 15 containing a higher B / P ratio produces an image with a slightly lower image density on glossy paper compared to others containing methacrylic acid ester monomer. The ink obtained in examples 2, 12 and 15, having lower Tg and obtained in example 3, containing finely dispersed particles of polymer B, give images that are better in scratch resistance on glossy paper.

Table 7
Compositions and properties of ink for recording obtained in examples 1-4, 6, 12 and 15 and the results of their evaluation example 1 example 2 example 3 example 4 example 6 example 12 Example 15 dispersible colorant one 2 3 four 6 12 fifteen Fine-dispersed particles of polymer B - - MMA
AAA Bzma
VA
AAA - - Bzma
VA
AAA Tg [° C] 105 110 105 thirty 115 45 thirty polymer / pigment ratio (B / P ratio) 0.2 0.2 0.5 0.5 0.8 1,5 5.1 glossy image density
paper BUT AT AT BUT AT BUT AT gloss scratch resistance AT AT BUT BUT AT BUT BUT gloss BUT AT BUT BUT BUT BUT AT

BzMA: benzyl methacrylate, AAc: acrylic acid

MMA: methyl methacrylate, VA: butyl acrylate.

Industrial application

The present invention provides a dispersible colorant having a sufficiently high dispersion stability, in which the polymer component does not separate from the colorant, and which is stable over a long period of time, and a method for easily producing said colorant. The present invention also provides aqueous inks comprising an excellent dispersible colorant, an ink tank, an ink jet recording apparatus, an ink jet recording method, and ink jet recording images. Another advantage of the present invention is a dispersible colorant that can quickly dry on a recording substrate. Another advantage of the present invention is a dispersible colorant having high scratch resistance on the recording substrate. Another advantage of this invention is a dispersible colorant having excellent emission characteristics in an inkjet recording apparatus. Another advantage of the present invention is a dispersible colorant having excellent development on a recording substrate. A further advantage of the present invention is a dispersible colorant stably applied in high to medium and medium to low pH environments. The method in accordance with this invention makes it easy to obtain a dispersible dye having the above characteristics. A further advantage of the present invention is aqueous recording inks, which can produce a glossy image on a glossy recording substrate. A further advantage of the present invention is aqueous recording inks having excellent scratch resistance on a glossy recording substrate. Another advantage of the present invention are aqueous recording inks having excellent storage stability over long periods of time.

Claims (20)

1. Dispersible dye containing a dye and pseudo-fine particles of a polarizable polymer having a size smaller than the dye particles, where the dye and particles are attached to each other, and the pseudo-fine particles of a polarizable polymer contain a copolymer of monomer components containing at least one type of hydrophobic monomer and at least one type of hydrophilic monomer, where the hydrophobic monomer contains at least a monomer having a methyl group in the α-position and a radical no-polymerizable unsaturated double bond. 2. Dispersible dye according to claim 1, which has a density of surface functional groups of not less than 250 μmol / g and not more than 1000 μmol / g 3. Dispersible dye according to claim 1, which has a surface energy of 70 mJ / m ² or less. 4. Dispersible dye according to claim 1, in which the component copolymer containing pseudo-fine particles of a polarizable polymer has a glass transition temperature of not less than -40 ° C and not more than 60 ° C. 5. Dispersible dye according to claim 1, in which the hydrophobic monomer contains at least a compound of (meth) acrylic ester. 6. The dispersible colorant of claim 5, wherein the hydrophobic monomer contains at least one compound selected from the group consisting of benzyl methacrylate and methyl methacrylate. 7. Dispersible dye according to any one of claims 1 to 6, in which the hydrophilic monomer contains at least anionic monomer. 8. Dispersible dye according to claim 7, in which the anionic monomer contains at least one compound selected from the group consisting of acrylic acid, methacrylic acid and p-styrenesulfonate salts. 9. A dispersible colorant according to any one of claims 1 to 6, wherein at least a cationic monomer is used as the hydrophilic monomer. 10. A method of producing a dispersible dye, comprising the step of carrying out a polymerization process by precipitating in a water medium a radical polymerizable monomer in an aqueous dispersion of a water-insoluble dye, using a radical water polymerisation initiator to combine a water-insoluble dye with pseudo-fine dispersed particles of a polarizable polymer. 11. The method of producing a dispersible dye of claim 10, in which the aqueous dispersion of a water-insoluble dye is an aqueous solution containing a pigment dispersed with a polymer dispersant having an acid number of not less than 100 and not more than 250. 12. The method of producing a dispersible dye according to claim 11, in which the dispersant is a copolymer of monomer components containing at least one type of monomer selected from the group consisting of acrylic acid, methacrylic acid and styrene monomer. 13. The method of producing a dispersible dye according to claim 11, in which the initiator of radical polymerization in water is anionic or ampholytic. 14. The method of obtaining a dispersible dye according to claim 10, in which the aqueous dispersion of a water-insoluble dye is an aqueous solution containing a pigment dispersed with a polymer dispersant having an acid number of not less than 150 and not more than 300. 15. The method of producing a dispersible dye according to 14, in which the initiator of radical polymerization in water is cationic or ampholytic. 16. The method of producing a dispersible dye according to claim 10, in which the radically polymerizable monomer component is added to the polymerization system. 17. The method of producing a dispersible dye of claim 10, in which the radically polymerizable monomer component contains at least one type of hydrophobic monomer and at least one type of hydrophilic monomer. 18. The method of producing a dispersible dye of claim 10, in which the initiator of radical polymerization in water is an initiator of azo-base polymerization in water. 19. Dispersible dye obtained by the method according to any one of paragraphs.10-18. 20. Aqueous inks containing a dispersible colorant according to any one of claims 1 to 9 and 19.

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