JP2006008811A - Dispersible coloring material and aqueous inkjet recording ink containing the coloring material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recorded image which is excellent in image quality, especially image density and solid density uniformity, and an aqueous ink, an inkjet recording device and an inkjet recording method which provide the same. <P>SOLUTION: A dispersible coloring material has a coloring material and a charged resin-like particulate smaller than the coloring material, wherein the coloring material and the charged resin-like particulate are stuck to each other. The charged resin-like particulate is at least capable of ultraviolet absorption and/or light stabilization and/or antioxidation. The aqueous ink contains the dispersible coloring material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a dispersible color material, an aqueous inkjet recording ink using the color material, an inkjet recording apparatus, an inkjet recording method, and an inkjet recorded image.

  The ink jet method is a method for recording images, characters, etc. by causing a micro droplet of ink to fly from a nozzle to reach a recording medium (paper, etc.) based on various operating principles. It is easy to realize, has high flexibility in recording patterns, and does not require development and fixing operations, and is rapidly spreading in various applications. In particular, in recent years, full-color water-based inkjet recording technology has been remarkably developed, and it is possible to form multicolored images that are comparable to multicolor printing by conventional platemaking methods and printing by color photographic methods. In the case where the number of copies to be produced is small, printed matter can be obtained at a lower cost than ordinary multicolor printing or printing, so that it has been widely applied to the field of full-color image recording.

  In response to demands for further improvement in recording characteristics such as higher recording speed, higher definition, and full color, improvements in aqueous inkjet recording apparatuses and recording methods have been made. In general, the performance required for the ink for ink jet recording used in the ink jet recording apparatus is as follows: (1) A uniform image with high resolution and high density without blurring or fogging can be obtained on the paper; 2) Clogging due to ink drying at the nozzle tip does not occur, and ejection responsiveness and ejection stability are always good. (3) Ink fixability is good on paper. (4) Image robustness. Properties (that is, weather resistance, water resistance, etc.) and (5) good long-term storage stability. In particular, as the printing speed increases, there is a demand for ink that can quickly dry and fix the ink and obtain high-quality printing even when printing on plain paper such as copy paper. Furthermore, in recent years, printed materials using the inkjet recording method have rapidly spread in the printing field, and the demand for further weather resistance has increased along with the expansion of not only fixing speed and image quality, but also outdoor use. Yes.

  The coloring materials used in the water-based inkjet recording method mainly include dyes and pigments. Conventionally, water-soluble dyes have been mainly used because of their ease of handling as water-based inks and high color developability. As a coloring material for water-based inkjet recording ink that can achieve weather resistance and water resistance, development of an ink that uses an essentially water-insoluble coloring material, particularly a pigment, has been energetically advanced.

  In order to use a color material insoluble in water, particularly a pigment, as an aqueous inkjet recording ink, it is necessary to stably disperse the color material in water. In this case, generally, a method of stabilizing the dispersion using a surfactant or a polymer dispersant (hereinafter also referred to as a dispersion resin) has been used. In addition, a technique for chemically modifying the surface of a water-insoluble colorant has been proposed (see, for example, Patent Document 1).

  On the other hand, a microcapsule type pigment in which a pigment is coated with a resin has been proposed (see, for example, Patent Documents 2 and 3). In Patent Document 3, “in a water-based colored fine particle dispersion containing a water-insoluble colorant, the colored fine particle dispersion is added with a vinyl monomer after the water-insoluble colorant is dispersed in an aqueous medium in the presence of the dispersant. When the dispersant is dispersed with a water-insoluble colorant, it exhibits dispersion stability, and when the vinyl monomer is polymerized only in the presence of the dispersant, the stability of the latex that is produced A water-based colored fine particle dispersion characterized by poor properties "is disclosed, and when the emulsion polymerization is performed on a water-insoluble colorant dispersion, the affinity of the dispersant for the vinyl monomer and the resulting polymer is not so high. For this reason, the desorption of the dispersant from the pigment surface is unlikely to occur, and the polymerization has proceeded on the pigment surface where the dispersant is adsorbed. ” By using the colored fine particle dispersion, it is excellent in dispersion stability and printability, is not dependent on the paper type, has a low metallic luster, water resistance, light resistance, and scratch resistance. It is said that an ink for ink jet recording that gives an image with excellent properties is obtained.

  In addition, various ultraviolet absorbers and light stabilizers have been studied for the purpose of improving the weather resistance of the image, and it is said that an image having excellent weather resistance can be obtained by adding them (see, for example, Patent Document 4). ).

Japanese Patent Laid-Open No. 10-195360 JP-A-8-183920 JP 2003-34770 A JP-A-5-239389

  However, with the above-described technology, there are cases in which both the dispersion stability of ink and the long-term storage stability are not sufficient. In the method of chemically modifying the surface of the water-insoluble colorant by the method shown in Patent Documents 1 and 2, there is a limit to the functional group that can be modified and its density, and the colorant is particularly an organic pigment When the chemical modification is performed directly on the pigment, the pigment molecules that are originally insoluble in water and crystallized are solubilized by the bonding of hydrophilic groups and dissolved from the pigment particles. Such a problem arises (see FIGS. 6 (a) and 6 (b)) that the technical level is not sufficiently satisfactory.

  According to Patent Document 4, the weather resistance is improved by adding an ultraviolet absorber or an antioxidant to the dye ink, but these added additives diffuse in the recording medium together with the liquid. Therefore, a sufficient effect cannot be obtained with respect to the added amount, and when the additive is increased, the ink characteristics are deteriorated. Thus, according to the study by the present inventors, it was not satisfactory enough.

  Therefore, the object of the present invention is to solve these problems, and to produce a recorded image having sufficiently high dispersion stability, stable for a long period of time, functioning efficiently with respect to the amount of the desired functional agent, and having excellent weather resistance. To provide water-based ink. Another object of the present invention is to provide an aqueous ink jet recording ink, an ink tank, an ink jet recording apparatus, an ink jet recording method, and an ink jet recorded image using such an excellent aqueous ink.

  On the other hand, as a result of earnestly examining the means for solving the above problems, the present inventors have found that at least one function selected from ultraviolet absorbing ability, light stabilizing ability, and antioxidant ability (hereinafter referred to as “coloring material protecting function”). By developing a water-based ink containing a novel dispersible color material having a high degree of weatherability, development of a water-based ink that provides a recorded image that is stable for a long time and has excellent weather resistance has been achieved.

The above object is achieved by the present invention described below.
1. A dispersible color material having a color material and a chargeable resin pseudo fine particle smaller than the color material, wherein the charge property is the above-mentioned chargeability in the dispersible color material to which the color material and the charge resin pseudo fine particle are fixed. A dispersible color material, wherein the resin pseudo fine particles have a color material protecting function.
2. 2. The dispersion according to 1 above, wherein the chargeable resin pseudo fine particles include at least one functional agent (hereinafter sometimes referred to as “coloring material protective agent”) selected from an ultraviolet absorber, a light stabilizer, and an antioxidant. Sex color material.

3. 2. The dispersible color material according to 1 above, wherein the chargeable resin pseudo fine particles are a polymer composed of an ethylenically unsaturated monomer having a color material protecting function.
4). 4. A water-based ink comprising the dispersible colorant according to any one of items 1 to 3.
5. 5. An ink tank comprising the water-based ink as described in 4 above.
6). 5. An ink jet recording apparatus comprising the water-based ink described in 4 above.

7). 5. An ink jet recording method comprising forming an image by an ink jet recording apparatus using the water-based ink described in 4 above.
8). 5. An ink jet recorded image formed by an ink jet recording apparatus using the water-based ink described in 4 above.

  According to the present invention, it is possible to provide an aqueous ink that has a sufficiently high dispersion stability, is stable for a long period of time, and provides a recorded image having excellent weather resistance. Furthermore, according to the present invention, it is possible to provide an aqueous inkjet recording ink, an ink tank, an inkjet recording apparatus, an inkjet recording method, and an inkjet recorded image using such an excellent aqueous ink.

The present invention will be specifically described below with reference to preferred embodiments.
A feature of the present invention is a dispersible color material having a color material and chargeable resin pseudo fine particles smaller than the color material, and the dispersible color material is fixed to the color material and the chargeable resin pseudo fine particles. The dispersible colorant is characterized in that the chargeable resin pseudo fine particles have a colorant protection function. The characteristics of the dispersible color material and the components of the dispersible color material will be described in detail below.

[Characteristics of dispersible colorants]
The dispersible color material is a dispersible color material composed of a color material and a chargeable resin pseudo fine particle, and the color material fixes the chargeable resin pseudo fine particle, and the chargeable resin pseudo particle is adhered to the surface of the color material. It is a dispersible color material that is charged with fine particles and can be dispersed in water or an aqueous ink medium. FIG. 1 is a schematic diagram of a dispersible color material, which characterizes the present invention, in which chargeable resin pseudo fine particles 2 are fixed to a color material 1. A portion 2 ′ in FIG. 1B is a portion schematically showing a state in which a part of the chargeable resin pseudo fine particles 2 fixed to the surface of the color material 1 is fused.

  Adsorption between the surface of the color material and the chargeable resin pseudo fine particles is not simple physical adsorption of the resin component, but is a state in which the chargeable resin pseudo fine particles are fixed to the color material, which is a characteristic of the dispersible color material according to the present invention Then, since the chargeable resin pseudo fine particles are not detached from the surface of the color material, the dispersible color material of the present invention is excellent in long-term storage stability.

  In the present invention, the state in which the coloring material “fixes” the chargeable resin pseudo fine particles can be simply confirmed by a technique involving the following three stages of separation. First, in the first separation, the color material to be confirmed is separated from other water-soluble components (including water-soluble resin components) contained in the ink or water dispersion, and then the second In the separation, the coloring material and the water-insoluble resin component contained in the precipitate in the first separation are separated. Furthermore, in the third separation, the weakly adsorbed resin component is separated from the dispersible colorant fixing the charged resin pseudo fine particles, and the quantitative determination of the resin component contained in the third separation supernatant, Then, the adhesion between the coloring material and the chargeable resin pseudo fine particles is confirmed by comparing the precipitate of the second separation and the precipitate of the third separation.

  Specifically, for example, it can be confirmed under the following conditions. Take 20 g of the ink or water dispersion in which the color material is dispersed and prepare it so that the total solid content weight is about 10%, and the first in a centrifuge at 12,000 rpm for 60 minutes. Separation. Of the separated substances, the lower sediment containing the coloring material is redispersed in pure water approximately three times the amount of the sediment, and then the second sediment is obtained at 80,000 rpm for 90 minutes. Perform separation. The lower layer containing the color material is subjected to the third separation again under the condition of 80,000 rotations and 90 minutes by redispersing the sediment of the lower layer containing the color material in 3 times the amount of pure water. Remove the sediment. The sediment in the second separation and the sediment in the third separation were each taken to have a solid content of about 0.5 g and dried under reduced pressure at 30 ° C. for 18 hours using a scanning electron microscope. Observe at 50,000 times. Then, it was confirmed that the observed dispersible colorant had a plurality of fine particle-like substances or fine aggregates equivalent thereto attached to the surface, and the respective sediments from the second separation and the third separation. If it has the same form, it is judged that this coloring material has fixed the resin pseudo fine particles. Further, the supernatant of the upper layer in the third separation is gently taken from the top so that the volume is about half, and the solid content weight is calculated from the weight change before and after drying at 60 ° C. for 8 hours, and 1% If it is less than that, it is considered that the resin pseudo fine particles are not detached from the dispersible color material, and it can be determined that the dispersible color material fixes the resin pseudo fine particles.

  The above-described separation conditions are preferable examples, and any other separation method or separation condition can be used as long as the method achieves the purpose of the first separation and the second and third separations described above. It can be applied as a method for determining whether or not it is a dispersible colorant.

  The dispersible color material used in the present invention is a dispersible color material in which the water-insoluble color material 1 is dispersed alone with the chargeable resin pseudo fine particles 2 fixed thereto. As described above, the dispersible colorant according to the present invention is essentially self-dispersible, which can be stably dispersed in water and water-based inks without the aid of other surfactants or polymer dispersants. It is a color material. This definition and determination method will be described in detail later.

  The self-dispersibility of the dispersible colorant of the present invention can be confirmed, for example, as follows. The ink or water dispersion in which the color material is dispersed is diluted 10-fold with pure water, and concentrated to the original concentration using an ultrafiltration filter having a molecular weight cut off of 50,000. This concentrated solution is separated in a centrifuge at 12,000 rpm for 2 hours, and the sediment is taken out and redispersed in pure water. At this time, it is judged that what the sediment can redisperse well has self-dispersibility. Whether or not it is well re-dispersed depends on whether it is uniformly distributed visually, or if there is no noticeable sediment during standing for 1 to 2 hours, or if it is shaken lightly It can be comprehensively judged from the fact that the average particle size is less than twice the particle size before operation when the dispersed particle size is measured by the dynamic light scattering method.

  As described above, the dispersible colorant according to the present invention takes a form having a high specific surface area by fixing the chargeable resin pseudo fine particles, and has a large amount of charges on its vast surface. Realizes excellent storage stability. Such a form is confirmed by observing the water-based inkjet recording ink of the present invention with a transmission electron microscope or a scanning electron microscope.

  The dispersible color material of the present invention is characterized in that the chargeable resin pseudo fine particles fixed to the color material have a color material protection function. As a method for imparting a coloring material protecting function to the chargeable resin pseudo fine particles, a method of incorporating a color material protecting agent into the chargeable resin pseudo fine particles, or a raw material component of a resin that forms the chargeable resin pseudo fine particles. Examples of the monomer include a method using a monomer having a coloring material protecting function.

  When an ultraviolet absorber or an antioxidant is externally added to the water-based ink, the color material and the ultraviolet absorber or the antioxidant are diffused as the ink penetrates into the recording medium. By fixing the chargeable resin fine particles having a color material protection function in the color material, the components that contribute to these effects are surely present in the vicinity of the color material, and thus contribute to the color material protection effect. The component can act on the colorant very effectively.

Next, each component of the dispersible color material (A) will be described.
[Color material]
The color material that is a constituent component of the dispersible color material according to the present invention will be described below. As the coloring material used in the present invention, any known or newly developed coloring material can be used, but preferably a hydrophobic dye, an inorganic pigment, an organic pigment, a metal colloid, a colored resin. It is desirable that the colorant is insoluble in water, such as particles, and can be stably dispersed in water together with the dispersant. Preferably, a coloring material having a dispersed particle size in the range of 0.01 to 0.5 μm (10 to 500 nm), particularly preferably in the range of 0.03 to 0.3 μm (30 to 300 nm) is used. The dispersible color material of the present invention using the color material dispersed in this range is a preferable dispersible color material that gives an image having high coloring power and high weather resistance when used as an aqueous ink.

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

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

  Other organic insoluble colorants that can be used in the present invention include, for example, azo, anthraquinone, indigo, phthalocyanine, carbonyl, quinoneimine, methine, quinoline, nitro, etc. Dyes. Of these, disperse dyes are particularly preferable.

[Charged resin pseudo fine particles with color material protection function]
The chargeable resin pseudo fine particles (hereinafter referred to as chargeable resin pseudo fine particles) having a color material protecting function, which is another constituent of the dispersible color material of the present invention, are substantially insoluble in water, and are to be fixed. The dispersion unit (dispersion particle diameter) of the coloring material in water (or in the ink) is small, and is defined as a microscopic body formed by collecting resin components having a sufficiently high degree of polymerization. The form of the minute body is pseudo close to a sphere, or a plurality of minute bodies (chargeable resin pseudo fine particles) are arranged within a certain range. It is preferable that the resin components constituting the chargeable resin pseudo fine particles are physically or chemically cross-linked with each other. The dispersion particle diameter of the chargeable resin pseudo fine particles in water is usually used in the range where the average cumulant value is 10 nm or more and 200 nm or less when it can be measured by the dynamic light scattering method.

  In the present invention, the chargeability refers to a state in which a functional group that is ionized in some form in the aqueous medium itself is retained, and is preferably self-dispersible by the chargeability. One method of imparting the above performance to the chargeable resin pseudo fine particles is to incorporate a dye protective agent into the chargeable resin pseudo fine particles.

  The presence of the color material protective agent in the charged resin pseudo fine particles includes physical interaction such as hydrophobic-hydrophobic interaction with the hydrophobic component of the resin forming the charge resin pseudo fine particles, and electrostatic charge with the charged site. May exist in any form, such as a chemical interaction such as a chemical interaction, an ionic bond, or a chemical bond. Further, the color material protective agent may be incorporated into the chargeable resin pseudo fine particles or may be present on the surface of the fine particles.

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

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

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

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

  Specific examples of nonionic hydrophilic monomers include, for example, monomers having a radically polymerizable unsaturated bond and a hydroxyl group exhibiting strong hydrophilicity in the structure, and (meth) acrylic. Hydroxyethyl acid, hydroxylpropyl (meth) acrylate, etc. are classified into this. In addition, various known or novel oligomers and macromonomers can be used without limitation.

  Furthermore, it is also preferable to use a crosslinkable monomer. For example, divinylbenzene, allyl (meth) acrylate, methylene bisacrylamide and the like can be mentioned, and other known or novel various crosslinking monomers can also be used.

[Synthesis of charged resin pseudo fine particles containing color material protective agent and fixation to color material]
The method for synthesizing the chargeable resin pseudo fine particles containing the color material protecting agent and the method for fixing to the color material are known procedures and methods for synthesizing the charge resin pseudo fine particles, and the charge resin pseudo fine particles and the color material. It can be carried out by the complexing method.

  As a result of the study by the present inventors, it has been clarified that the dispersible colorant according to the present invention having the above-described characteristics can be produced very easily by applying the aqueous precipitation polymerization method under the following conditions. . In such a production method, first, a water-insoluble colorant is dispersed with a dispersant to prepare a dispersed aqueous solution of the water-insoluble colorant. Subsequently, in this dispersed aqueous solution, the chargeable resin pseudo fine particles containing the color material protective agent are colored by a step of aqueous precipitation polymerization of the radical polymerizable monomer in the presence of the color material protective agent using an aqueous radical polymerization initiator. It is fixed to. The dispersible colorant obtained through this aqueous precipitation polymerization process is a water-insoluble color in which the chargeable resin pseudo fine particles synthesized in the aqueous precipitation polymerization process are strongly and firmly adhered to the colorant. It becomes a material and has excellent dispersion stability by itself.

[Radically polymerizable monomer]
Since the radically polymerizable monomer used in the production method of the present invention becomes a component constituting the chargeable resin pseudo fine particles through the aqueous precipitation polymerization step described above, the above [substantially water-insoluble resin fine particles ], As described in the section, may be appropriately selected depending on the characteristics of the chargeable resin pseudo fine particles and the dispersible colorant to be obtained.

  When preparing a water-based ink using the water-insoluble color material obtained by the above-described steps and having the chargeable resin pseudo fine particles fixed to the color material according to the present invention, in addition to the above steps, further purification treatment is performed. It is desirable to do. In particular, in the above, it is possible to carry out purification treatment on unreacted polymerization initiator, monomer component, dispersant, water-soluble resin component that has not been fixed, and chargeable resin pseudo fine particles, etc. Is important in maintaining high. As a purification method to be used, an optimum one may be selected from generally used purification methods. For example, purification using a centrifugal separation method or an ultrafiltration method is a preferred embodiment.

[Coloring material protective agent]
The color material protective agent used in the present invention is not particularly limited and may be a known material or, of course, a new substance developed for the present invention.
Examples of the ultraviolet absorber include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) -5-chloro. Benzotriazole ultraviolet absorbers such as benzotriazole, benzophenone ultraviolet absorbers such as 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, phenyl Phenylsalicylic acid UV absorbers such as salicylate and 4-t-butylphenyl salicylate, Oxalic acid bisallinide UV absorbers such as 2-ethoxy-2'-ethyloxalic acid bisallinide, 2-ethylhexyl 2-cyano-3,3-diphenyl acrylate, ethyl-2- Cyanoacrylate ultraviolet absorbers Ano-3,3'-diphenyl acrylate.

  Examples of the light stabilizer include bis- [2,2,6,6-tetramethyl-4-piperidinyl] sebacate, bis- (1,2,2,6,6-pentamethyl-4-piperidinyl) -2- ( And hindered amine light stabilizers such as 3,5-di-tetra-butyl-4-hydroxybenzyl) -2-n-butylmalonate.

  Antioxidants include phenolic antioxidants such as 2,6-t-dibutyl-p-cresol, stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2 Bisphenol antioxidants such as' -methylenebis (4-methyl-6-t-butylphenol), sulfur antioxidants such as dilauryl-3,3'-thiodipropionate, triphenyl phosphite, diphenylisodecyl phos Examples thereof include phosphorus antioxidants such as phyto.

  In the present invention, whether or not the chargeable resin pseudo fine particles fixed to the dispersible color material contain a color material protective agent can be determined as follows. Centrifugation is performed at 5,000 rpm for 10 minutes to remove the agglomerated components, and then further centrifugation is performed at 12,500 rpm for 2 hours to obtain a dispersible colorant. The dispersible colorant is redispersed in water and a 10% hydrochloric acid aqueous solution is added to obtain a precipitate. The precipitate is subjected to Soxhlet extraction with an organic solvent such as methyl ethyl ketone, and then the presence of the dye protecting agent is confirmed by high performance liquid chromatography, gas chromatography or the like.

[Fixing of chargeable resin pseudo fine particles containing a monomer having a color material protection function to the color material]
In the present invention, as a method for imparting a color material protection function to the chargeable resin pseudo fine particles, a monomer having a color material protection function is used as a monomer that is a raw material component of the resin forming the chargeable resin pseudo fine particles. Methods and the like.

  Specifically, as described in the section of [Synthesis of charged resin pseudo fine particles containing color material protecting agent and fixing to color material], an aqueous precipitation polymerization method can be applied. In the aqueous dispersion of a water-insoluble colorant, as described in the previous section “Resin microparticles that are substantially insoluble in water” and a radically polymerizable monomer having a colorant-protecting function using an aqueous radical polymerization initiator. Further, it can be obtained by polymerization with a radical polymerizable monomer or the like.

[Radically polymerizable monomer having color material protection function]
As the radical polymerizable monomer having a color material protecting function, any of general-purpose radical polymerizable monomers and radical polymerizable monomers developed for the present invention can be used. Examples thereof include monomers having sites such as a benzophenone skeleton, a benzotriazole skeleton, a hindered phenol skeleton, a salicylate skeleton, a cyanoacrylate skeleton, and a hindered amine skeleton. Specifically, 2- (2′-hydroxy-5-methylacryloxyethylphenyl) -2H-benzotriazole (manufactured by Otsuka Chemical Co., Ltd.) containing a benzotriazole skeleton having ultraviolet absorption ability, and a light stabilizing ability having a hindered amine skeleton 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate (Asahi Denka Kogyo Co., Ltd.), 2,2,6,6-tetramethyl-4-piperidyl methacrylate (Asahi Denka Kogyo Co., Ltd.) ) And the like.

  In the dispersible colorant, it can be determined by the following method, for example, whether the chargeable resin pseudo fine particles are a polymer composed of an ethylenically unsaturated monomer having a colorant protecting function. Centrifugation is performed at 5,000 rpm for 10 minutes to remove the agglomerated components, and then further centrifugation is performed at 12,500 rpm for 2 hours to obtain a dispersible colorant. The dispersible colorant is redispersed in water and a 10% hydrochloric acid aqueous solution is added to obtain a precipitate. After the precipitate is subjected to Soxhlet extraction with an organic solvent such as methyl ethyl ketone, an ethylenically unsaturated monomer having a coloring material protecting function as a raw material monomer can be detected by pyrolysis gas mass chromatography.

[Water-based ink]
The aqueous inkjet recording ink according to the present invention includes the dispersible colorant according to the present invention described above. When the water-insoluble colorant is a pigment, the pigment content is generally 0.1 to 20% by mass, preferably 0.3 to 15% by mass with respect to the ink. Furthermore, it is also preferable to contain water and a water-soluble organic solvent as an aqueous medium as required. Further, it may contain a penetrant, an antiseptic, an antifungal agent and the like for helping the permeability to the recording medium.

[Recorded image]
The ink jet recording image according to the present invention is formed on a recording medium by an ink jet recording apparatus as will be described later, using the aqueous ink of the present invention including the color material having the above-described configuration. The recording medium used in the present invention can be used without limitation even if it is a medium capable of ink jet recording.

[Image recording method and recording apparatus]
The dispersible color material and the water-based ink containing the color material according to the present invention are used in an ink jet discharge type head, and also as an ink tank in which the ink is stored or an ink for filling the ink tank It is also effective. In particular, the present invention provides an excellent effect in a bubble jet (registered trademark) type recording head and recording apparatus among ink jet recording methods.

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

  As the configuration of the recording head, in addition to the combination configuration (linear liquid channel or right-angle liquid channel) of the discharge port, the liquid channel, and the electrothermal transducer as disclosed in each of the above-mentioned specifications, the heat acting part The present invention is also effective for configurations using US Pat. No. 4,558,333 and US Pat. No. 4,459,600, which disclose configurations in which the lens is disposed in a bending region. In addition, the present invention is also effective for a configuration (Japanese Patent Laid-Open No. 59-123670, etc.) in which a discharge hole is used as a discharge portion of the electrothermal transducer when common to a plurality of electrothermal transducers. . Furthermore, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length is set by combining a plurality of recording heads as disclosed in the above specification. Either the satisfying configuration or the configuration as a single recording head formed integrally may be used, but the present invention can exhibit the above-described effects more effectively.

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

  Next, an Example and a comparative example are given and this invention is demonstrated concretely. The present invention is not limited by the following examples unless it exceeds the gist. In the text, “part” or “%” is based on mass unless otherwise specified.

[Example 1]
A recording ink 1 according to Example 1 was prepared in the following manner.
<Adjustment of dispersible colorant (A-1)>
First, a mixed liquid composed of 10 parts of a yellow pigment (CI Pigment Yellow 74), 10 parts of a styrene-acrylic acid resin dispersant, and 74 parts of water was mixed with a sand mill manufactured by Kanada Rika Kogyo Co., Ltd. The pigment dispersion 1 was obtained by dispersing at 500 rpm for 5 hours. In the sand mill, zirconia beads having a diameter of 0.6 mm were used, and the filling rate in the pot was 70%. A styrene-acrylic acid resin dispersant having a copolymerization ratio of 70:30, Mw = 8,000, and an acid value of 170 was used. As this styrene-acrylic acid resin dispersant, water and potassium hydroxide equivalent to the above acid value were added in advance and stirred at 80 ° C. to obtain an aqueous solution. The resulting pigment dispersion 1 had an average dispersed particle size of 110 nm.

  Next, 100 parts of the pigment dispersion 1 obtained above was added at 70 ° C. under a nitrogen atmosphere, and the following two kinds of mixed liquids were gradually added dropwise at the same time, followed by polymerization for 5 hours. . The mixed solution was composed of 5.5 parts of methyl methacrylate and 0.5 part of 2,4-dihydroxybenzophenone, 0.5 part of acrylic acid, 0.12 part of potassium hydroxide, 0.05 part of potassium persulfate. And 20 parts of water. The obtained dispersion was diluted 10 times and centrifuged at 5,000 rpm for 10 minutes to remove the aggregating components. Then, it further refine | purified by centrifuging on conditions of 12,500 rpm and 2 hours, and the dispersible color material 1 which is a sediment was obtained.

  This dispersible colorant 1 is dispersed in water, centrifuged at 12,000 rpm for 60 minutes, and the precipitate redispersed in water is dried, and then scanned with an electron microscope JSM-6700 (JEOL Hi-Tech). When the dispersible colorant 1 was observed at a magnification of 50,000 times, a state where the resin fine particles were fixed to the surface of the pigment was observed.

  Dispersible colorant 1 was redispersed in water, and a 10% aqueous hydrochloric acid solution was added to obtain a precipitate. The precipitate was dried, and the dried product was Soxhlet extracted with tetrahydrofuran. When the extract was analyzed by high performance liquid chromatography (Waters), 2,4-dihydroxybenzophenone was detected.

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

[Example 2]
100 parts of Pigment Dispersion Liquid 1 was added dropwise at 70 ° C. under a nitrogen atmosphere while simultaneously adding the following two kinds of mixed liquids while stirring, and polymerization was performed for 5 hours. The mixed solution is a mixed solution composed of 5.0 parts of methyl methacrylate and 1.0 part of 2- (2′-hydroxy-5-methylacryloxysethylphenyl) -2H-benzotriazole, 0.5 part of acrylic acid. , 0.12 part of potassium hydroxide, 0.05 part of potassium persulfate and 20 parts of water. The obtained dispersion was diluted 10 times and centrifuged at 5,000 rpm for 10 minutes to remove the aggregating components. Then, it further refine | purified by centrifuging on conditions of 12,500 rpm and 2 hours, and the dispersible color material 2 which is a sediment was obtained.

This dispersible colorant 2 is dispersed in water, centrifuged at 12,000 rpm for 60 minutes, and the precipitate redispersed in water is dried, and then scanned with an electron microscope JSM-6700 (JEOL Hi-Tech). When the dispersible colorant 2 was observed at a magnification of 50,000 times, a state where the resin fine particles were fixed to the surface of the pigment was observed.
The same components as in Example 1 were mixed so that the obtained colorant dispersion 2 had a concentration of 4% in the ink, and further filtered under pressure with a membrane filter having a pore size of 2.5 microns, The recording ink 2 of this example was used.

  The dispersible colorant 2 was redispersed in water and a 10% aqueous hydrochloric acid solution was added to obtain a precipitate. The precipitate was dried, and the dried product was Soxhlet extracted with tetrahydrofuran. When the extract was analyzed by pyrolysis gas mass chromatography (Waters), a fragment derived from 2- (2'-hydroxy-5-methylacryloxysethylphenyl) -2H-benzotriazole was detected.

[Reference example]
100 parts of Pigment Dispersion Liquid 1 was added dropwise at 70 ° C. under a nitrogen atmosphere while simultaneously adding the following two kinds of mixed liquids while stirring, and polymerization was performed for 5 hours. The mixed solution is a mixed solution consisting of 6.0 parts of methyl methacrylate, 0.5 part of acrylic acid, 0.12 part of potassium hydroxide, 0.05 part of potassium persulfate and 20 parts of water. The obtained dispersion was diluted 10 times and centrifuged at 5,000 rpm for 10 minutes to remove the aggregating components. Then, it further refine | purified by centrifuging on conditions of 12,500 rpm and 2 hours, and the dispersible color material 3 which is a sediment was obtained.

  This dispersible colorant 2 is dispersed in water, centrifuged at 12,000 rpm for 60 minutes, and the precipitate redispersed in water is dried, and then scanned with an electron microscope JSM-6700 (JEOL Hi-Tech). When the dispersible colorant 3 was observed at a magnification of 50,000 times, a state where the resin fine particles were fixed on the surface of the pigment was observed. The same components as in Example 1 were mixed so that the resulting color material dispersion 3 had a concentration of 4% in the ink, and further filtered under pressure with a membrane filter having a pore size of 2.5 microns, The recording ink 3 of this reference example was obtained.

[Evaluation method and evaluation result of water-based inkjet recording ink]
Using each recording ink obtained by the above-described method, the ink characteristics were evaluated as follows. Further, printing on a recording medium was performed with an inkjet recording apparatus, and the obtained images were evaluated. A color text image was formed using BJ S600 marketed by Canon Inc. as the ink jet recording apparatus used. And the weather resistance of the printed matter printed was evaluated as follows, and the result was shown in Table 1.

<Long-term storage stability of ink>
Storage stability was determined by visual observation of the state of dispersion in the ink after each ink was placed in a glass sample bottle and allowed to stand at room temperature for one month in that state. The evaluation criteria are as follows.
A: No aggregation or sedimentation of solid content is observed.
B: Sedimentation of solid content is slightly observed, but when shaken lightly, it returns to the original uniform dispersion state.
C: Aggregation / sedimentation of solid content is observed, and even if lightly shaken, it does not become uniform.

<Weather resistance>
Text was printed on glossy paper (PR101 manufactured by Canon Inc.) using each recording ink. A weather resistance test was performed on the recorded image having an image density of about 1.0 under the following conditions. The image density after the test was measured, and the image density before and after the test was compared.

[Weather resistance test]
The recorded image was subjected to a weather resistance test with a xenon fade meter under the conditions of 0.39 W / m ² and 100 hr.

[Image density]
The image density of the image before and after the weather resistance test was measured with a reflection densitometer (RD914 from Macbeth).

  As shown in Examples 1 and 2, a water-based ink that gives an image having excellent dispersion stability and excellent weather resistance can be obtained.

  According to the present invention, a novel dispersible color material is provided. Also provided are water-based inks, ink jet recording inks, ink tanks, ink jet recording apparatuses, and ink jet recording methods using such dispersible color materials. As another effect of the invention, a water-based ink that provides an image having excellent dispersion stability and excellent weather resistance is provided.

It is a schematic diagram which shows the basic structure of the dispersible color material which has fixed the chargeable resin pseudo fine particles by this invention. It is a schematic diagram of the typical process in the manufacturing method of this invention. It is a schematic diagram which shows the refinement | purification of the chargeable resin pseudo fine particles and the adhering process to a color material in the manufacturing method of this invention. It is the schematic diagram which expanded the chargeable resin pseudo fine particle of this invention from the interface side fixed to a coloring material. It is the schematic diagram which expanded the interface which the chargeable resin pseudo fine particles of this invention and the coloring material adhere. It is a schematic diagram of a pigment peeling phenomenon when a hydrophilic group is directly modified on an organic pigment, represented by Patent Document 1.

Explanation of symbols

1: Color material 1a: Part of color material 2: Charged resin pseudo fine particles 3: Dispersion resin 4: Monomer 5: Polymerization initiator aqueous solution 6: Dispersible color material 7: Oligomer 8 formed by polymerizing monomers: Precipitate in which oligomer is insolubilized in water 9-1: Hydrophilic monomer unit portion 9-2 in charged resin pseudo fine particle: Hydrophobic monomer unit portion 10 in charged resin pseudo fine particle 10: Binding site 11 with coloring material 11: Interfacial portion 12 of the chargeable resin pseudo fine particle with the color material: hydrophilic group 13 directly modified with the color material 13: hydrophilic color material molecule

Claims (8)

  A dispersible color material having a color material and a chargeable resin pseudo fine particle smaller than the color material, wherein the charge property is the above-mentioned chargeability in the dispersible color material to which the color material and the charge resin pseudo fine particle are fixed. A dispersible colorant, wherein the resin pseudo fine particles have at least one function selected from an ultraviolet absorbing ability, a light stabilizing ability, and an antioxidant ability.   The dispersible colorant according to claim 1, wherein the chargeable resin pseudo fine particles include at least one functional agent selected from an ultraviolet absorber, a light stabilizer, and an antioxidant.   2. The polymer according to claim 1, wherein the chargeable resin pseudo fine particles are a polymer composed of an ethylenically unsaturated monomer having at least one function selected from an ultraviolet absorbing ability, a light stabilizing ability, and an antioxidant ability. Dispersible colorant.   A water-based ink comprising the dispersible colorant according to any one of claims 1 to 3.   An ink tank comprising the water-based ink according to claim 4.   An ink jet recording apparatus comprising the water-based ink according to claim 4.   An ink jet recording method comprising forming an image by an ink jet recording apparatus using the water-based ink according to claim 4. An ink jet recording image formed by an ink jet recording apparatus using the water-based ink according to claim 4.

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