JP4697133B2 - Method for producing microencapsulated color material - Google Patents

Description

The present invention relates to a microencapsulated material in which the surface of a core material is coated with a wall material mainly composed of a polymer, a microencapsulated color material using color material particles as the core material, and a method for producing the same. Further, the present invention relates to an ink composition containing the microencapsulated color material and particularly suitable as an ink composition for inkjet recording.
The present invention also relates to an ink jet recording method using the ink composition and a recorded matter using the recording method.

  As an inkjet recording ink, an aqueous pigment ink in which a pigment is dispersed in water is provided. This is because the ink using the pigment has the characteristics that the water resistance and the light resistance are superior to the ink using the water-soluble dye. In such a water-based pigment ink, it is generally performed to disperse a pigment in an aqueous dispersion medium using a dispersant such as a surfactant or a polymer dispersant.

  For example, in Patent Document 1, in a pigment ink using an acetylene glycol penetrant, a polymer dispersant is used as a dispersant for pigment particles, and water, a non-volatile organic solvent, and a lower alcohol are used as an aqueous medium. Studies are being conducted to ensure the dispersion stability. However, when a dispersant is used to disperse pigment particles in this way, there are many factors that need to be adjusted in the ink composition in order to obtain various characteristics desirable for the ink, and the ink physical properties such as viscosity are adjusted to desired values. Difficult to do. Moreover, it is difficult to obtain a printed matter having a sufficiently high printing density using this pigment ink.

  Further, in these water-based pigment inks, the dispersant is simply adsorbed on the surface of the pigment particles, and on the other hand, when the ink liquid is ejected through the thin nozzles of the nozzle head, the pigment particles Since a strong shearing force is applied to the surface of the pigment particles, the dispersant adsorbed on the surface of the pigment particles is detached, and as a result, the dispersibility of the pigment is lowered and the ink liquid tends to be unstable. Further, when the water-based pigment ink is stored for a long period of time, there is a case where the dispersibility tends to become unstable.

  As another technique for dispersing pigment particles in water, a technique for introducing sulfonic acid groups on the surface of the pigment particles has also been proposed. For example, a pigment ink containing a sulfonated surface-treated organic pigment obtained by treating an organic pigment dispersed in a solvent having no active protons with a sulfonating agent is known (Conventional Example 1; see, for example, Patent Document 2). ). According to Conventional Example 1, it is said that the pigment ink has excellent dispersion stability and discharge stability from the nozzles of the recording head (characteristic that the recording head is stably discharged in a certain direction). Yes.

  In addition, a method for preparing an organic pigment mass that positively charges the surface by treating the organic pigment mass into which the sulfonic acid group has been introduced with a monovalent metal ion is known. A water-based ink composition having excellent storage stability (dispersion stability) containing pigment fine particles prepared from a body, a dispersant, and water has been described (Conventional Example 2; see, for example, Patent Document 3).

  However, the ink using the surface-treated pigment particles of Conventional Example 1 and Conventional Example 2 as a colorant is superior in dispersion stability and ejection stability compared to conventional pigment-based inkjet recording inks. The rubbing resistance of the recorded matter obtained by printing this on a recording medium such as plain paper or an ink jet recording medium (a recording medium having an ink receiving layer for receiving ink for ink jet recording on the surface) is still unsatisfactory. It was enough. This is presumably because the fixability of the surface-treated pigment particles on the recording medium is not good.

  Further, for the purpose of improving the fixability of a pigment contained in a pigment-based ink jet recording ink to a recording medium, a polymer obtained by graft polymerizing the surface of pigment particles has been proposed (for example, see Patent Document 4). In these formulations, the pigment is generally prepared by surface-treating the pigment, generating a functional group on the pigment surface, and then graft polymerizing the polymer to the functional group. However, the amount of functional groups generated on the pigment surface by the surface treatment is limited, and the amount of polymer also depends on the amount of functional groups, so that it is difficult to sufficiently cover the pigment surface with the polymer. The recorded material obtained cannot be said to have sufficient abrasion resistance.

  On the other hand, for the purpose of improving the fixability of a pigment contained in a pigment-based inkjet ink to a recording medium, an ink using a pigment coated with a resin having a film-forming property at room temperature by a phase inversion emulsification method (for example, see Patent Document 5). And an ink using a pigment coated with an anionic group-containing organic polymer compound by an acid precipitation method (for example, see Patent Document 6).

  Furthermore, an ink using a polymer emulsion obtained by impregnating polymer fine particles with a colorant by a phase inversion emulsification method has been proposed (Conventional Example 3; see, for example, Patent Document 7). However, even in the colorant obtained by the phase inversion emulsification method or the acid precipitation method, depending on the type of the organic solvent such as the penetrant used in the ink, the polymer adsorbed on the pigment particles may be desorbed in the ink. In some cases, the ink may be dissolved, and ink dispersion stability, ejection stability, image quality, and the like may not be sufficient. In the ink of Conventional Example 3, since the polymer adsorbed on the pigment particles is desorbed not a little, the pigment content in the ink is limited from the viewpoint of dispersion stability. The recorded image has a low print density. In particular, when plain paper is used as the recording medium, there is a problem that the image tends to blur and the color developability is low.

On the other hand, a technique using a microencapsulated pigment in which colorant particles are coated with a polymer is known for the purpose of improving the fixability of a pigment contained in a pigment-based inkjet ink to a recording medium.
A method of microencapsulating pigment fine particles (for example, see Patent Document 8) and a method of microencapsulating a hydrophobic powder using an amphiphilic graft polymer have been proposed (for example, see Patent Document 9). The method described in the above patent document has a problem that the particle size after microencapsulation becomes too large.

  Further, as a microencapsulated pigment in which colorant particles are coated with a polymer, a method of aggregating particles by mixing an emulsion of an emulsifiable polymer resin in an anionic medium with a cationic surfactant dispersion of the pigment Has been proposed (Patent Document 10), but since a surfactant is used, depending on the solvent in the ink, the surfactant may be easily detached from the pigment, resulting in insufficient dispersion stability. There is a problem.

  In addition, a method for preparing a microencapsulated pigment by coating a pigment with a surfactant or a polymer having emulsifying ability, and then introducing a monomer and an initiator to polymerize the pigment is proposed (Patent Document 11). . However, all of these methods introduce monomers into the pigment interface and polymerize them, so there is a limit to the amount of monomers introduced and the surface coating tends to be insufficient. Depending on the solvent in the ink, dispersion stability There is a problem that is insufficient.

JP-A-3-157464 Japanese Patent Laid-Open No. 10-110129 JP-A-11-49974 JP-A-5-339516 JP 2000-7961 A Japanese Patent Application Laid-Open No. 11-199783 JP-A-9-286939 JP 2003-306611 A JP-A-5-320276 JP-A-9-124985 JP 2004-189928 A

The present invention has been made in view of the above-described conventional situation, and a microencapsulated color material capable of producing an ink for inkjet recording satisfying all of the following (1) to (6), and a method for producing the same: An object of the present invention is to provide an ink composition containing the microencapsulated color material, an ink jet recording method using the ink composition, and a recorded matter using the recording method.
(1) When used as a coloring material for an ink composition, it is excellent in dispersion stability in an aqueous dispersion.
(2) When the ink composition is used, the ejection stability from the recording head is excellent.
(3) When an ink composition is used, a recorded matter having excellent image fastness can be obtained.
(4) When an ink composition is used, a recorded matter having a high image printing density can be obtained.
(5) When an ink composition is used, a recorded matter having excellent image abrasion resistance can be obtained.
(6) When an ink composition is used, even when plain paper is used as a recording medium, it is possible to obtain a recorded matter in which an image is difficult to bleed and an image is highly colored.

Another object of the present invention is to provide a microencapsulated product satisfying all of the following i) to vi).
i) The core material can be either inorganic or organic.
ii) The thickness of the shell layer (core material coating layer) can be designed freely.
iii) Environmentally friendly.
iv) The function can be separated between the core material and the shell material.
v) It can be made less toxic or harmless by encapsulation of toxic core material.
vi) A powder having a particle size can be produced.

  As a result of diligent research regarding a method for microencapsulating a core material represented by pigment particles with a wall material mainly composed of a polymer, the present inventors have previously obtained a polymer having an ionic group on the surface of the core material particle. By adsorbing and forming a polymer of a polymer having an ionic group having a charge opposite to that of the polymer, a monomer having a polymerizable group and / or a polymerizable surfactant on the surface of the core material, It has been found that the object of the present invention can be achieved by microencapsulating the core material, and the present invention has been completed.

The method for producing the microencapsulated color material of the present invention includes :
(1) A first step of adsorbing the polymer A having an ionic group on the surface of the colorant particle in an aqueous medium. (2) The polymer in the aqueous dispersion of the colorant particle having the polymer A adsorbed on the surface. Second step of adding and mixing polymer B having an ionic group having a charge opposite to that of ionic group of A (3) Hydrophilic monomer, hydrophobic monomer and polymerizability to the aqueous dispersion It comprises a third step of mixing and polymerizing one or more selected from the group consisting of surfactants and a polymerization initiator (claim 1 ).

In this method for producing a microencapsulated color material, in the second step, the total amount of dissociated ionic groups of the entire polymer B added to the aqueous dispersion is the entire polymer A adsorbed on the surface of the color material particles. It is preferable that the total number of dissociated ionic groups is greater than ( 2 ).

In the second step, the polymer B preferably contains a polymerizable group (claim 3 ).

In the third step, one or more selected from the group consisting of a hydrophobic monomer and a polymerizable surfactant and a polymerization initiator are homogenized and then added to the aqueous dispersion. It is preferable to emulsify (claim 4 ).

  The microencapsulated color material of the present invention is excellent in dispersion stability in an aqueous dispersion when used as a color material for an ink composition. The ink composition of the present invention containing such a microencapsulated color material of the present invention has excellent ejection stability from the recording head, excellent image fastness, high image print density, and image resistance. A recorded matter having excellent rubbing properties can be obtained. In addition, according to the ink jet recording method of the present invention using such an ink composition of the present invention, even when plain paper is used as a recording medium, a recorded matter that is difficult to bleed and has high color developability of the image is obtained. Obtainable.

Further, the microencapsulated product of the present invention can be applied to the core material, whether it is inorganic or organic, and the thickness of the shell layer (core material coating layer) can be freely designed. In addition, since it can be produced by a water-based reaction without using a solvent, it does not adversely affect the environment, and it can be made less toxic or harmless by encapsulation of a toxic core material. Is possible.
Furthermore, according to the microencapsulated material of the present invention, the function can be separated between the core material and the shell material, and a powder having a uniform surface state and particle size can be produced. The effect of.

Hereinafter, embodiments of the present invention will be described in detail.
The description of the constituent requirements described below is an example (representative example) of an embodiment of the present invention, and the present invention is not specified in these contents unless it exceeds the gist.

The microencapsulated color material of the present invention is a microencapsulated color material in which the surface of color material particles is coated with a wall material mainly composed of a polymer, and the polymer is
1) Polymer A having an ionic group;
2) a polymer B having an ionic group having a charge opposite to that of the ionic group of the polymer A;
3) having a repeating structural unit derived from one or more selected from the group consisting of a hydrophilic monomer, a hydrophobic monomer and a polymerizable surfactant.

Such a microencapsulated color material of the present invention is
(1) A first step of adsorbing the polymer A having an ionic group on the surface of the colorant particle in an aqueous medium. (2) The polymer in the aqueous dispersion of the colorant particle having the polymer A adsorbed on the surface. Second step of adding and mixing polymer B having an ionic group having a charge opposite to that of ionic group of A (3) Hydrophilic monomer, hydrophobic monomer and polymerizability to the aqueous dispersion Preferably produced by the method for producing a microencapsulated color material of the present invention comprising a third step of polymerizing a polymerization initiator by mixing one or more selected from the group consisting of surfactants and a polymerization initiator. can do.

  The microencapsulated material of the present invention has the same configuration as the above-described microencapsulated color material of the present invention except that a core material other than the color material is used instead of the color material particles.

  Here, the ionic group having a charge opposite to the charge of the ionic group of the substance means a negative charge if the charge of the ionic group on the surface of the colorant particle is positive. If the charge of the ionic group on the surface of the material particle is negative, it means a positive charge. The same kind of charge means a positive charge for a positive charge and a negative charge for a negative charge.

  Hereinafter, the microencapsulated color material of the present invention will be described along with various raw materials used for producing the microencapsulated color material and a method for producing a microencapsulated color material using these materials.

[Color material particles]
As the color material that becomes the core material of the microencapsulated color material of the present invention, either a water-insoluble or water-nondispersible material, a water-soluble or water-dispersible material can be used. Examples of water-insoluble or non-dispersible colorant particles include water-nondispersible pigments and water-insoluble dyes, and examples of water-soluble or water-dispersible colorant particles include water-soluble dyes and water-dispersible pigments. It is done. Among these, pigments are preferable from the viewpoints of color developability and weather resistance, and water non-dispersible pigments that do not require pretreatment are particularly preferable, and water non-dispersible pigments increase the efficiency of polymer adsorption on the particle surface. Therefore, those having as few aqueous functional groups as possible are more preferable.
Specific examples of the color material particles suitable for the present invention are listed below, but the color material particles according to the present invention are not limited to the following.

<Water non-dispersible pigment>
Examples of inorganic pigments include carbon blacks such as furnace black, lamb black, acetylene black, and channel black (Cl pigment black 7), iron oxide pigments, and the like.
Organic pigments include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments), polycyclic pigments (eg, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane Pigments, thioindigo pigments, isoindolinone pigments, or quinofuranone pigments), dye chelates (including basic dye-type chelates or acidic dye-type chelates, etc.), nitro pigments, nitroso pigments, aniline black Can be mentioned. These include black pigments, cyan pigments, magenta pigments, and yellow pigments. If desired, other color pigments can also be used in the present invention.

These pigments that can be used in the present invention will be further described in detail.
Examples of the inorganic pigment carbon black used for black include No. 1 manufactured by Mitsubishi Chemical Corporation. 2300, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, No2200B, etc. (above, trade names); Raven 5750, Raven 5250, Raven 5000, Raven 3500, Raven 1255, Raven 1700, etc. (above, trade names) manufactured by Columbia; Regal 400R, Regal manufactured by Cabot Corporation 330R, Regal 660R, Mogul L, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, and Monarch 1400, etc. (above, trade names); or ckF made by Degussa 1 Color Black FW2, Color Black FW2V, Color Black FW18, Color Black FW200, Color Black S150, Color Black S160, Color Black S170, Printex 35, Printex U, Printex V, Printex 140U, Special Black 6, Spic, Bc Name).
Moreover, as the organic pigment for black, a black organic pigment such as aniline black (C.I. Pigment Black 1) can be used.

  Examples of organic pigments for yellow ink include C.I. l. Pigment Yellow 1 (Hansa Yellow); 2,3 (Hansa Yellow 10G); 4,5 (Hansa Yellow 5G); 6,7,10,11,12,13,14,16,17,24 (Flavans) Tron Yellow); 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, 99, 108 (anthrapyrimidine yellow); 109, 110 113, 117 (copper complex pigment); 120, 124, 128, 129, 133 (quinophthalone); 138, 139 (isoindolinone); 147, 151, 153 (nickel complex pigment); and 154 , 167, 172, 180 and the like.

  Examples of organic pigments for magenta ink include C.I. l. Pigment Red 1 (Paral Red); 2, 3 (Toluidine Red); 4, 5 (lTR Red); 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38 (pyrazolone red); 40, 41, 42, 48 (Ca); 48 (Mn), 57 (Ca), 57: 1, 88 (Thioindigo); 112 (naphthol AS); 114 (naphthol AS); 122 (dimethylquinacridone); 123, 144, 146, 149, 150, 166, 168 (antanthrone orange); 170 ( Naphthol AS system); 171, 175, 176, 177, 178, 179 (berylene maroon); 184, 185, 187, 202, 209 (dichloroquinacrid) Down); the 219,224 (perylene-based); the 245 (Naphthol AS yarn), or, C. I. Pigment violet 19 (quinacridone); 23 (dioxazine violet); 32, 33, 36, 38, 43, 50, and the like.

  Examples of organic pigments for cyan ink include C.I. l. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15:34, 15: 4, 16 (metal-free phthalocyanine); 18 (alkali blue toner); 22, 25, 60 (slen blue); 65 (violanthrone); 66 (indigo); and C.I. l. Vat blue 4, 60 and the like can be mentioned.

  Organic pigments used for color inks other than magenta, cyan or yellow inks include C.I. I. Pigment Green 7 (phthalocyanine green); 10 (green gold); 36, 37; C.I. I. Pigment brown 3, 5, 25, 26; and C.I. I. Pigment Orange 1, 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43, 63, and the like.

  As the colorant particles according to the present invention, one of the above pigments can be used alone, or two or more can be used in combination. It can also be used in combination with other color materials.

<Water-dispersible pigment>
The water-dispersible pigment has a hydrophilic group on the particle surface, and the production method is not particularly limited, but it can be suitably prepared by treating the surface of the pigment particle with a hydrophilic group-imparting agent. .
The pigment constituting the pigment particles having a hydrophilic group on the surface is not particularly limited as long as it is a pigment that does not dissolve in the hydrophilic group-imparting agent, and the pigments mentioned as the water non-dispersible pigment can be used.
The hydrophilic group-imparting agent is not particularly limited, but is a sulfonating agent such as sulfuric acid, fuming sulfuric acid, sulfur trioxide, sulfonated pyridine salt or sulfamic acid, sodium hypochlorite or hypochlorite. Examples thereof include a carboxylating agent such as potassium acid and a cationizing agent such as diazonium salt.

<Water-insoluble dye>
The water-insoluble dye is not particularly limited, and examples thereof include oil-soluble dyes, disperse dyes, water-insoluble metal-containing dyes, vat dyes, other photochromic dyes, and resin colorants. Of these, oil-soluble dyes and disperse dyes having good color developability are preferred.

<Water-soluble dye>
Although it does not specifically limit as a water-soluble dye, For example, an acidic dye, a direct dye, a basic dye, a water-soluble metal-containing dye, a reactive dye etc. are mentioned. Among these, acidic dyes, direct dyes, and basic dyes having good color developability are preferable.

[Polymer A]
When the microencapsulated color material of the present invention is produced, first, a treatment for adsorbing the polymer A having an ionic group is performed on the surface of the color material particles as described above (first step).
Here, when a water-insoluble dye or a water non-dispersible pigment is used as the color material particles, the polymer A to be adsorbed on the surface of the color material particles is either an anionic or cationic ion in the polymer A. It is preferable to use those having a functional group and a hydrophobic group.
In general, inks for inkjet use are neutral to weakly alkaline for maintenance of the apparatus, and the ionic group in the outermost shell of the colorant is preferably an anionic group. Accordingly, although not particularly limited, the ionic group of the polymer A in the microencapsulated color material of the present invention is a cationic group, which reverses the charge of the outermost shell to an anionic group during capsule formation. It is more preferable because it can be easily made.
Specific examples of the polymer A having an ionic group and a hydrophobic group include the following.

<Polymer A having an ionic group and a hydrophobic group>
The polymer A containing both an ionic group and a hydrophobic group is not particularly limited as long as it has an ionic group and a hydrophobic group. For example, the polymer may be a synthetic polymer or a natural polymer such as a polysaccharide, or a derivative or modified product thereof.
Examples of the polymer A used in the present invention include homopolymers, random copolymers, diblock copolymers, triblock or more multiblock copolymers, gradient copolymers, graft copolymers, star copolymers, and the like.
The polymer A may contain a hydrophilic nonionic group as long as it contains both an ionic group and a hydrophobic group.

  The method for synthesizing the polymer A is not particularly limited. For example, a known polymerization method such as radical polymerization, ionic polymerization, polyaddition, polycondensation can be selected, and the polymer A is a derivative or modification of a polymer synthesized by these known methods. It may be a body. Among these, a polymer synthesized using a radical polymerization method is preferable because the synthesis method is simple. Among radical polymerization methods, a polymer having a narrow molecular weight distribution is obtained, and therefore, a polymer synthesized using a living radical polymerization method is most preferable. Monomers used for synthesizing these polymers by radical polymerization include hydrophobic monomers, anionic monomers, and cationic monomers exemplified below, but are not limited to the following examples, and are conventionally Known monomers can be used.

(Hydrophobic monomer)
Examples of hydrophobic monomers include olefins such as ethylene, propylene, 1-butene, and isobutene; methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, acrylic Acrylic acid esters such as i-butyl acid, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate , Methacrylic acid esters such as n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate; styrene, o-methoxystyrene, m-methoxystyrene Styrenes such as p-methoxystyrene, ot-butoxystyrene, mt-butoxystyrene, pt-butoxystyrene, o-chloromethylstyrene, m-chloromethylstyrene, p-chloromethylstyrene; N- Acrylamide derivatives such as methyl acrylamide, N-ethyl acrylamide, N, N-dimethyl acrylamide, diacetone acrylamide, N-methylol acrylamide and derivatives thereof; N-methyl methacrylamide, N-ethyl methacrylamide, N, N-dimethyl methacryl Methacrylamide derivatives such as amide, diacetane methacrylamide, N-methylol methacrylamide and derivatives thereof; methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, -Vinyl ethers such as butyl vinyl ether, t-butyl vinyl ether, benzyl vinyl ether, dodecyl vinyl ether and stearyl vinyl ether; Nitriles such as acrylonitrile and methacrylonitrile; Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride and vinylidene fluoride Examples: Allyl compounds such as allyl acetate and allyl chloride; dicarboxylic acid ester derivatives such as maleic acid ester and itaconic acid ester; vinylsilyl compounds such as vinyltrimethoxysilane; isopropenyl acetate and the like. These monomers may be used individually by 1 type, and may use 2 or more types together.

(Anionic monomer)
Examples of anionic monomers include carboxylic acid monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid; vinyl sulfonic acid, allyl sulfonic acid, methacryl sulfonic acid, styrene sulfonic acid, and 2-acrylamide ethane sulfone. Acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-methacrylamideamidoethanesulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid, 2-acryloyloxyethanesulfonic acid, 3-acryloyloxypropanesulfonic acid, 4 -Sulfonic acid monomers such as acryloyloxybutanesulfonic acid, 2-methacryloyloxyethanesulfonic acid, 3-methacryloyloxypropanesulfonic acid, 4-methacryloyloxybutanesulfonic acid; vinylphosphonic acid, Taacryloxyethyl phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxyethyl phosphate, dibutyl-2-methacryloyloxyethyl phosphate, dioctyl-2- Examples thereof include phosphoric acid monomers such as (meth) acryloyloxyethyl phosphate; and metal salts or ammonium salts of these alkali metals and alkaline earth metals. These monomers may be used individually by 1 type, and may use 2 or more types together.

(Cationic monomer)
Examples of cationic monomers include dimethylamino (methyl, ethyl, propyl or butyl) acrylate or methacrylate, diethylamino (methyl, ethyl, propyl or butyl) acrylate or methacrylate, di-n-propylamino (methyl, ethyl, propyl or butyl). ) Acrylate or methacrylate, diisopropylamino (methyl, ethyl, propyl or butyl) acrylate or methacrylate, di-n-butylamino (methyl, ethyl, propyl or butyl) acrylate or methacrylate, di-sec-butylamino (methyl, ethyl, Propyl or butyl) acrylate or methacrylate, diisobutylamino (methyl, ethyl, propyl or butyl) acrylate or methacrylate, dimethyla (Methyl, ethyl, propyl or butyl) acrylamide or methacrylamide, diethylamino (methyl, ethyl, propyl or butyl) acrylamide or methacrylamide, di-n-propylamino (methyl, ethyl, propyl or butyl) acrylamide or methacrylamide, Diisopropylamino (methyl, ethyl, propyl or butyl) acrylamide or methacrylamide, di-n-butylamino (methyl, ethyl, propyl or butyl) acrylamide or methacrylamide, di-sec-butylamino (methyl, ethyl, propyl or butyl) ) Acrylamide or methacrylamide, diisobutylamino (methyl, ethyl, propyl or butyl) acrylamide or methacrylamide, vinylpyridine, 2-methyl 5-vinylpyridine, 2-ethyl-5-vinylpyridine, N, N-dimethylaminostyrene, N, N-dimethylaminomethylstyrene, or a neutralized salt thereof such as hydrogen halide, sulfuric acid, nitric acid, organic acid, etc. Quaternized compounds such as alkyl halides, benzyl halides, dimethyl sulfate, diethyl sulfate and the like can be mentioned. These monomers may be used individually by 1 type, and may use 2 or more types together.

  When a water-soluble dye or a water-dispersible pigment is used as the color material particles, the polymer A adsorbed on the surface of the color material particles may contain either an anionic or cationic ionic group in the polymer. Others are not limited. For example, it is possible to use a polymer having the above-described ionic group and hydrophobic group, or a polymer that does not contain a hydrophobic group among these polymers.

  If the molecular weight of the polymer A is too large, the viscosity of the liquid increases and it becomes difficult to disperse the particles, the final dispersion becomes highly viscous and the dispersion stability decreases, and if it is too small, the heat resistance decreases, The number average molecular weight is preferably 2,000 or more and 50,000 or less, more preferably 5,000 or more and 20,000 or less because the solvent in the ink facilitates detachment from the particle surface.

  Polymer A may be used alone or in combination of two or more.

  Next, in the aqueous dispersion of colorant particles obtained by adsorbing the polymer A on the surface as described above, at least an ionic group having a charge opposite to the charge of the ionic group of the polymer A is included. After adding and mixing one kind of polymer B (second step), one or more kinds selected from the group consisting of at least one kind of hydrophilic monomer, hydrophobic monomer and polymerizable surfactant in this dispersion liquid or By adding two or more kinds, the aqueous dispersion is emulsified to form micelles (third step), and by adding a polymerization initiator to this to polymerize (fourth step), the surface of the colorant particles is formed. The microencapsulated color material of the present invention is obtained by being coated with an organic polymer and microencapsulated.

[Polymer B]
In the present invention, as a second step, the polymer B having an ionic group having a charge opposite to the charge of the ionic group of the polymer A is added to the aqueous dispersion of the colorant particles adsorbed by the polymer A. In addition, a mixing process is performed. As the polymer B added to the aqueous dispersion of the colorant particles adsorbed by the polymer A, for example, the following one having an ionic group having a charge opposite to the charge of the polymer A in the polymer is used. Can do.

The polymer B should just contain the ionic group which has the electric charge opposite to the electric charge which the said polymer A has, and others are not limited. For example, the polymer may be a synthetic polymer or a natural polymer such as a polysaccharide, or a derivative or modified product thereof.
Examples of the polymer B used in the present invention include homopolymers, random copolymers, diblock copolymers, triblock or more multiblock copolymers, gradient copolymers, graft copolymers, star copolymers, and the like.
Further, the polymer B only needs to contain an ionic group, and may further contain a hydrophobic group or a hydrophilic nonionic group.

  The method for synthesizing the polymer B is not particularly limited. For example, a known polymerization method such as radical polymerization, ionic polymerization, polyaddition, polycondensation can be selected, and the polymer B is a derivative or modification of a polymer synthesized by these known methods. It may be a body. Among these, a polymer synthesized using a radical polymerization method is preferable because the synthesis method is simple. Among radical polymerization methods, a polymer having a narrow molecular weight distribution is obtained, and therefore, a polymer synthesized using a living radical polymerization method is most preferable. Monomers used for synthesizing these polymers by radical polymerization include anionic monomers, cationic monomers, hydrophobic monomers, and hydrophilic (water-soluble) nonionic monomers exemplified below. It is not limited to these examples, and conventionally known monomers can be used.

(Anionic monomer)
Examples of anionic monomers include carboxylic acid monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid; vinyl sulfonic acid, allyl sulfonic acid, methacryl sulfonic acid, styrene sulfonic acid, and 2-acrylamide ethane sulfone. Acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-methacrylamideamidoethanesulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid, 2-acryloyloxyethanesulfonic acid, 3-acryloyloxypropanesulfonic acid, 4 -Sulfonic acid monomers such as acryloyloxybutanesulfonic acid, 2-methacryloyloxyethanesulfonic acid, 3-methacryloyloxypropanesulfonic acid, 4-methacryloyloxybutanesulfonic acid; vinylphosphonic acid, Taacryloxyethyl phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxyethyl phosphate, dibutyl-2-methacryloyloxyethyl phosphate, dioctyl-2- Examples thereof include phosphoric acid monomers such as (meth) acryloyloxyethyl phosphate; and metal salts or ammonium salts of these alkali metals and alkaline earth metals. These monomers may be used individually by 1 type, and may use 2 or more types together.

(Cationic monomer)
Examples of cationic monomers include dimethylamino (methyl, ethyl, propyl or butyl) acrylate or methacrylate, diethylamino (methyl, ethyl, propyl or butyl) acrylate or methacrylate, di-n-propylamino (methyl, ethyl, propyl or butyl). ) Acrylate or methacrylate, diisopropylamino (methyl, ethyl, propyl or butyl) acrylate or methacrylate, di-n-butylamino (methyl, ethyl, propyl or butyl) acrylate or methacrylate, di-sec-butylamino (methyl, ethyl, Propyl or butyl) acrylate or methacrylate, diisobutylamino (methyl, ethyl, propyl or butyl) acrylate or methacrylate, dimethyla (Methyl, ethyl, propyl or butyl) acrylamide or methacrylamide, diethylamino (methyl, ethyl, propyl or butyl) acrylamide or methacrylamide, di-n-propylamino (methyl, ethyl, propyl or butyl) acrylamide or methacrylamide, Diisopropylamino (methyl, ethyl, propyl or butyl) acrylamide or methacrylamide, di-n-butylamino (methyl, ethyl, propyl or butyl) acrylamide or methacrylamide, di-sec-butylamino (methyl, ethyl, propyl or butyl) ) Acrylamide or methacrylamide, diisobutylamino (methyl, ethyl, propyl or butyl) acrylamide or methacrylamide, vinylpyridine, 2-methyl 5-vinylpyridine, 2-ethyl-5-vinylpyridine, N, N-dimethylaminostyrene, N, N-dimethylaminomethylstyrene, or a neutralized salt thereof such as hydrogen halide, sulfuric acid, nitric acid, organic acid, etc. Quaternized compounds such as alkyl halides, benzyl halides, dimethyl sulfate, diethyl sulfate and the like can be mentioned. These monomers may be used individually by 1 type, and may use 2 or more types together.

(Hydrophobic monomer)
Examples of hydrophobic monomers include olefins such as ethylene, propylene, 1-butene, and isobutene; methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, acrylic Acrylic acid esters such as i-butyl acid, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate , Methacrylic acid esters such as n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate; styrene, o-methoxystyrene, m-methoxystyrene Styrenes such as p-methoxystyrene, ot-butoxystyrene, mt-butoxystyrene, pt-butoxystyrene, o-chloromethylstyrene, m-chloromethylstyrene, p-chloromethylstyrene; N- Acrylamide derivatives such as methyl acrylamide, N-ethyl acrylamide, N, N-dimethyl acrylamide, diacetone acrylamide, N-methylol acrylamide and derivatives thereof; N-methyl methacrylamide, N-ethyl methacrylamide, N, N-dimethyl methacryl Methacrylamide derivatives such as amide, diacetane methacrylamide, N-methylol methacrylamide and derivatives thereof; methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, -Vinyl ethers such as butyl vinyl ether, t-butyl vinyl ether, benzyl vinyl ether, dodecyl vinyl ether and stearyl vinyl ether; Nitriles such as acrylonitrile and methacrylonitrile; Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride and vinylidene fluoride Examples: Allyl compounds such as allyl acetate and allyl chloride; dicarboxylic acid ester derivatives such as maleic acid ester and itaconic acid ester; vinylsilyl compounds such as vinyltrimethoxysilane; isopropenyl acetate and the like. These monomers may be used individually by 1 type, and may use 2 or more types together.

(Water-soluble nonionic monomer)
Examples of water-soluble nonionic monomers include hydroxyl group-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, and 2-hydroxy. Examples include butyl methacrylate, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, and 2-hydroxy-3-phenoxypropyl acrylate.
In addition, as monomers having an amide group, acrylamide, methacrylamide, N-isopropylacrylamide, hydroxyethylacrylamide, acrylic acid aminoethylamide, acrylic acid methylaminoethylamide, acrylic acid methylaminopropylamide, acrylic acid ethylaminoethylamide , Ethyl aminopropylamide acrylate, aminopropyl amide acrylate, aminoethyl amide methacrylate, methylaminoethyl methacrylic acid methacrylate, methylaminopropyl methacrylic acid methacrylate, ethylaminoethyl methacrylic acid, ethyl aminopropylamide methacrylic acid, methacrylic acid Examples include aminopropylamide and vinyl pyrrolidone.
These monomers may be used individually by 1 type, and may use 2 or more types together.

  In the present invention, as the polymer B, it is desirable to use a polymer having a polymerizable group in the molecule. That is, it is desirable to use a polymer having a polymerizable group at the terminal and / or side chain of the polymer. Examples of the polymerizable group include acryloyl group, methacryloyl group, styryl group, vinylbenzyl group, allyl group, acrylamide group, vinyl ether group and the like. A polymer having a polymerizable group in the molecule is obtained by reacting with the reactive group after obtaining a reactive group-introduced polymer using a monomer having a reactive group such as a carboxyl group, an amino group or a hydroxyl group or a chain transfer agent. Can be synthesized by reacting a radical polymerizable unsaturated monomer such as glycidyl methacrylate and vinylbenzyl chloride with the above polymer.

  If the molecular weight of the polymer B is too large, the particles on which the polymer A has been adsorbed are remarkably aggregated so that the re-dispersion does not work. The final dispersion becomes highly viscous and the dispersion stability is lowered. The number average molecular weight is preferably 2,000 or more and 50,000 or less, more preferably 5,000 or more and 20,000 or less, because it is easy to be peeled off from the particles by the solvent in the ink.

  The polymer B may be used individually by 1 type, and may use 2 or more types together.

  In this second step, as long as at least one type of polymer B having a charge opposite to that of the ionic group of polymer A is used, a polymer other than polymer B is added. It doesn't matter. In this case, the other polymer is not particularly limited, and a hydrophobic polymer, a polymer having a water-soluble nonionic group and a hydrophobic group, and the like can be used.

[Hydrophilic monomer, hydrophobic monomer, polymerizable surfactant]
In the production of the microencapsulated color material of the present invention, the polymer B is added and mixed in an aqueous dispersion of color material particles obtained by adsorbing the polymer A on the surface as described above (second method). Step), one or more selected from the group consisting of a hydrophilic monomer, a hydrophobic monomer, and a polymerizable surfactant (hereinafter sometimes referred to as “monomer component C”) and polymerization in this dispersion. The micelle is formed by adding an initiator and mixing the aqueous dispersion (third step).

Examples of the monomer component C used in the third step include monomers exemplified below.
<Hydrophilic monomer>
Preferable specific examples of the hydrophilic monomer having an anionic group include carboxylic acid monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid and fumaric acid; vinyl sulfonic acid, allyl sulfonic acid, methacryl sulfonic acid, styrene sulfone. Acid, 2-acrylamidoethanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-methacrylamideamidoethanesulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid, 2-acryloyloxyethanesulfonic acid, 3- Sulfonic acid-based monoacids such as acryloyloxypropanesulfonic acid, 4-acryloyloxybutanesulfonic acid, 2-methacryloyloxyethanesulfonic acid, 3-methacryloyloxypropanesulfonic acid, 4-methacryloyloxybutanesulfonic acid -Vinylphosphonic acid, methacryloxyethyl phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxyethyl phosphate, dibutyl-2-methacryloyloxyethyl And phosphoric acid monomers such as phosphate and dioctyl-2- (meth) acryloyloxyethyl phosphate; and metal salts or ammonium salts of these alkali metals and alkaline earth metals.

  Moreover, as a hydrophilic monomer other than the hydrophilic monomer having an anionic group, as a monomer having a hydroxyl group, for example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, Examples include 2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, and 2-hydroxy-3-phenoxypropyl acrylate. Examples of the monomer having an amide group include acrylamide, methacrylamide, N-isopropylacrylamide, hydroxyethylacrylamide, acrylic acid aminoethylamide, acrylic acid methylaminoethylamide, acrylic acid methylaminopropylamide, and ethylaminoethyl acrylate. Amides, ethyl aminopropylamide acrylate, aminopropylamide acrylic acid, aminoethylamide methacrylate, methylaminoethylmethacrylate methacrylate, methylaminopropylamide methacrylate, ethylaminoethylmethacrylate methacrylate, ethylaminopropylamide methacrylate, methacrylic acid Acid aminopropylamide, vinyl pyrrolidone, etc. are mentioned.

  Furthermore, preferable specific examples of the hydrophilic monomer having a cationic group include dimethylaminoethyl methyl chloride methacrylate, dimethylaminoethyl benzyl methacrylate methacrylate, methacryloyloxyethyltrimethylammonium chloride, diallyldimethylammonium chloride, 2-hydroxy-3- And methacryloxypropyltrimethylammonium chloride.

  These may be used alone or in combination of two or more.

<Hydrophobic monomer>
Preferable specific examples of the hydrophobic monomer include, for example, olefins such as ethylene, propylene, 1-butene and isobutene; methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate and n-acrylate. Acrylic esters such as butyl, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, methacrylic acid Methacrylic acid esters such as i-propyl, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate; styrene, o-methoxystyrene, m −Me Styrenes such as xylstyrene, p-methoxystyrene, ot-butoxystyrene, mt-butoxystyrene, pt-butoxystyrene, o-chloromethylstyrene, m-chloromethylstyrene, p-chloromethylstyrene; Acrylamide derivatives such as N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, diacetone acrylamide, N-methylolacrylamide and derivatives thereof; N-methylmethacrylamide, N-ethylmethacrylamide, N, N- Methacrylamide derivatives such as dimethylmethacrylamide, diacethanemethacrylamide, N-methylolmethacrylamide and derivatives thereof; methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl Vinyl ethers such as ether, i-butyl vinyl ether, t-butyl vinyl ether, benzyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether; nitriles such as acrylonitrile and methacrylonitrile; vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, etc. Examples thereof include vinyl halides; allyl compounds such as allyl acetate and allyl chloride; dicarboxylic acid ester derivatives such as maleic acid ester and itaconic acid ester; vinylsilyl compounds such as vinyltrimethoxysilane; and isopropenyl acetate.

  These may be used alone or in combination of two or more.

In addition to the above-mentioned hydrophilic monomer and hydrophobic monomer, other polymerizable monomer components are used in order to polymerize the polymers A and B adsorbed on the surface of the colorant particles as long as the effects of the present invention are not impaired. be able to.
Examples of other polymerizable monomers used herein include crosslinkable monomers as exemplified below. The solvent resistance of the wall material can be improved by copolymerizing the crosslinkable monomer to form the wall material of the microencapsulated color material. By increasing the solvent resistance of the wall material, the dispersion stability of the microencapsulated color material particles can be improved even in an aqueous ink composition containing a solvent having a high affinity with the polymer constituting the wall material of the microencapsulated color material. It can be excellent.

<Crosslinkable monomer>
Examples of the crosslinkable monomer used in the present invention include compounds having two or more unsaturated hydrocarbon groups selected from a vinyl group, an allyl group, an acryloyl group, a methacryloyl group, a propenyl group, a vinylidene group and a vinylene group. For example, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, allyl acrylate, bis (acryloxyethyl) hydroxyethyl isocyanurate, bis (acryloxyneo) Pentyl glycol) adipate, 1,3-butylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, propylene Glycol diacrylate, polypropylene glycol diacrylate, 2-hydroxy-1,3-diacryloxypropane, 2,2-bis [4- (acryloxy) phenyl] propane, 2,2-bis [4- (acryloxyethoxy) ) Phenyl] propane, 2,2-bis [4- (acryloxyethoxy diethoxy) phenyl] propane, 2,2-bis [4- (acryloxyethoxy polyethoxy) phenyl] propane, hydroxypentyl glycol neopentyl glycol Diacrylate, 1,4-butanediol diacrylate, dicyclopentanyl diacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol Litol triacrylate, tetrabromopisphenol A diacrylate, triglycerol diacrylate, trimethylolpropane triacrylate, tris (acryloxyethyl) isocyanurate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene Glycol dimethacrylate, polyethylene glycol dimethacrylate, propylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol Dimethacrylate, 2-hydroxy-1,3-dimethacrylo Xylpropane, 2,2-bis [4- (methacryloxy) phenyl] propane, 2,2-bis [4- (methacryloxyethoxy) phenyl] propane, 2,2-bis [4- (methacryloxyethoxydiethoxy) phenyl ] Propane, 2,2-bis [4- (methacryloxyethoxypolyethoxy) phenyl] propane, tetrabromobisphenol A dimethacrylate, dicyclopentanyl dimethacrylate, dipentaerythritol hexamethacrylate, glycerol dimethacrylate, hydroxybivalic acid Neopentyl glycol dimethacrylate, dipentaerythritol monohydroxypentamethacrylate, ditrimethylolpropane tetramethacrylate, pentaerythritol trimethacrylate, pentaerythritol La methacrylate, triglycidyl Se roll dimethacrylate, trimethylolpropane trimethacrylate, tris (methacryloxyethyl) isocyanurate, allyl methacrylate, divinylbenzene, diallyl phthalate, diallyl terephthalate, diallyl isophthalate, and diethylene glycol bis allyl carbonate.

  These may be used alone or in combination of two or more.

<Monomer represented by general formula (7)>
In the third step, the monomer component C used for synthesizing the polymer that is the main component of the wall material of the microencapsulated color material of the present invention is further represented by the following general formula (7) within the range not impairing the effects of the present invention. ) Can be used.

（式中、Ｒ^１は水素原子又はメチル基を表す。Ｒ^２はｔ−ブチル基、脂環式炭化水素基、芳香族炭化水素基、又はヘテロ環基を表す。ｍは０〜３の整数を表し、ｎは０又は１の整数を表す。）

(In the formula, R ¹ represents a hydrogen atom or a methyl group. R ² represents a t-butyl group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, or a heterocyclic group. M is an integer of 0 to 3. And n represents an integer of 0 or 1.)

In the general formula (7), examples of the alicyclic hydrocarbon group represented by R ² include a cycloalkyl group, a cycloalkenyl group, an isobornyl group, a dicyclopentanyl group, a dicyclopentenyl group, and an adamantane group. Examples of the aromatic hydrocarbon group include a phenyl group, a naphthyl group, an anthranyl group, and a benzyl group. Examples of the heterocyclic group include a tetrahydrofuran group, which may further have a substituent.

  Specific examples of the monomer represented by the general formula (7) include the following.

  The monomers exemplified above may be used alone or in combination of two or more.

In the third step, the monomer represented by the general formula (7) is used as the monomer component C, and the polymer of the wall material of the microencapsulated color material of the present invention is represented by the general formula (7). By introducing the R ² group, which is a “bulky” group derived from a monomer, the flexibility of the molecule of the wall polymer is reduced, that is, the mobility of the molecule is reduced, and the mechanical strength of the polymer is reduced. And heat resistance can be increased. For this reason, the recorded matter recorded using the ink composition containing the microencapsulated color material coated with the polymer can have excellent abrasion resistance and durability. Further, the presence of the R ² group, which is a “bulky” group, in the polymer constituting the microcapsule wall material can suppress the penetration of the organic solvent in the ink composition into the polymer of the wall material, As a result, the solvent resistance of the microencapsulated color material can be improved, so that the ink composition in which the water-soluble organic solvent coexists can be ejected from the inkjet head, the dispersibility of the color material, the ink composition The shelf life of things can be improved.

  A polymer having a repeating structural unit derived from the crosslinkable monomer or a polymer having a repeating structural unit derived from the monomer represented by the general formula (7) has high Tg, mechanical strength, heat resistance, It has the advantage of excellent solvent resistance.

  However, since the microencapsulated color material coated with a polymer containing a large amount of the crosslinkable monomer and / or the monomer represented by the general formula (7) as a copolymerization component has low polymer plasticity, It may become difficult to adhere to. As a result, the fixability of the ink composition containing the microencapsulated color material to the recording medium and the abrasion resistance of the resulting image may be reduced, so the amount of these monomers used can be adjusted as appropriate. preferable.

  On the other hand, among the above-mentioned hydrophobic monomers, a polymer having a repeating structural unit derived from a monomer having a long-chain alkyl group has flexibility. Therefore, the ratio of the repeating structural unit derived from the crosslinkable monomer and / or the repeating structural unit derived from the monomer represented by the general formula (7) and the repeating structural unit derived from the monomer having a long-chain alkyl group. By appropriately adjusting the thickness, a wall material having excellent mechanical strength and excellent solvent resistance can be formed together with preferable plasticity. An ink composition containing microencapsulated colorant particles coated with such a polymer has excellent ejection stability from an ink jet head, even when it contains a water-soluble organic solvent, and has excellent dispersion stability and long-term storage. Also excellent in properties. Further, the ink composition containing the microencapsulated colorant particles has good fixability to a recording medium, and the image of the recorded matter recorded using the ink composition has excellent abrasion resistance, durability, and solvent resistance. Excellent.

<Polymerizing surfactant>
As the polymerizable surfactant that can be used in the third step for producing the microencapsulated color material of the present invention, a cationic polymerizable surfactant and an anionic polymerizable compound are used as long as the effects of the present invention are not impaired. Surfactants and nonionic polymerizable surfactants can be used, and examples thereof include the following polymerizable surfactants.

(Cationically polymerizable surfactant)
The cationic polymerizable surfactant used in the present invention is a compound having a cationic group as an ionic group, a hydrophobic group, and a polymerizable group.
The cationic group of the cationic polymerizable surfactant is preferably a cationic group selected from the group consisting of a primary ammonium cation, a secondary ammonium cation, a tertiary ammonium cation, and a quaternary ammonium cation. The primary ammonium cation is a monoalkyl ammonium cation (RNH ₃ ⁺ ) or the like, the secondary ammonium cation is a dialkyl ammonium cation (R ₂ NH ₂ ⁺ ) or the like, and the tertiary ammonium cation is a trialkyl ammonium cation (R ₃ NH). ⁺ ) And the like, and examples of the quaternary ammonium cation include (R ₄ N ⁺ ). Here, R is a hydrophobic group and a polymerizable group, and examples thereof include the following. Examples of the counter anion of the cationic group include Cl ⁻ , Br ⁻ , and I ⁻ .

The hydrophobic group of R is preferably one or more selected from the group consisting of an alkyl group and an aryl group, and has both an alkyl group and an aryl group in one surfactant molecule. You can also.
The polymerizable group of R is preferably an unsaturated hydrocarbon group, specifically, a group selected from the group consisting of vinyl group, allyl group, acryloyl group, methacryloyl group, propenyl group, vinylidene group and vinylene group. It is preferable that Among these, acryloyl group, methacryloyl group and allyl group are particularly preferable.

  Specific examples of the cationic polymerizable surfactant include cationic allyl acid derivatives and methacrylic acid derivatives as described in JP-B-4-65824.

For example, a compound represented by the general formula R ⁴⁴ _{[4- (a + b + c)]} R ⁴¹ _a R ⁴² _b R ⁴³ _c N ⁺ · Q ⁻ can be given (in the general formula, R ⁴⁴ is a polymerizable group). R ⁴¹ , R ⁴² and R ⁴³ are each an alkyl group or an aryl group, Q is Cl, Br or I, and a, b and c are each 1 or 0). Here, as the polymerizable group, a hydrocarbon group having an unsaturated hydrocarbon group capable of radical polymerization can be preferably exemplified, and more specifically, an allyl group, an acroyl group, a methacryloyl group, a vinyl group, a propylene group, and a propylene group. Nyl group, vinylidene group, vinylene group and the like can be mentioned.

  Specific examples of the cationic polymerizable surfactant include dimethylaminoethyl methyl chloride methacrylate, dimethylaminoethyl benzyl methacrylate, methacryloyloxyethyltrimethylammonium chloride, diallyldimethylammonium chloride, and 2-hydroxy- Examples thereof include 3-methacryloxypropyltrimethylammonium chloride salt.

Commercially available products may be used as the cationic polymerizable surfactant. For example, Acryester DMC (Mitsubishi Rayon Co., Ltd.), Acryester DML60 (Mitsubishi Rayon Co., Ltd.), and C-1615 (Daiichi Kogyo). Pharmaceutical Co., Ltd.).
The cationic polymerizable surfactants exemplified above may be used alone or in combination of two or more. It can also be used in combination with a nonionic polymerizable surfactant.

(Anionic polymerizable surfactant)
The anionic polymerizable surfactant used in the present invention is a compound having an anionic group, a hydrophobic group, and a polymerizable group as an ionic group.
Specific examples of the anionic polymerizable surfactant used in the present invention include anions as described in JP-B-49-46291, JP-B-1-24142, or JP-A-62-104802. Allyl derivatives, anionic propenyl derivatives as described in JP-A-62-221431, JP-A-62-34947 or JP-A-55-11525 Anionic acrylic acid derivatives, anionic itaconic acid derivatives as described in JP-B-46-34898 or JP-A-51-30284, and JP-A-62-11534 Examples thereof include an anionic compound having a radical polymerizable unsaturated carboxylic acid group and a sulfate group in the structure.

  As the anionic polymerizable surfactant used in the present invention, for example, a compound represented by the following general formula (1) or the following general formula (2) is preferable.

（式中、Ｒ^２１及びＲ^３１は、それぞれ独立して、水素原子又は炭素数１〜１２の炭化水素基であり、Ｚ^１は、炭素−炭素単結合又は式：
−ＣＨ_２−Ｏ−ＣＨ_２−
で表される基であり、ｘは２〜２０の整数であり、Ｘは式−ＳＯ_３Ｍ^１で表される基であり、Ｍ^１はアルカリ金属、アンモニウム基、又はアルカノールアミン残基である。）

(In the formula, R ²¹ and R ³¹ are each independently a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms, and Z ¹ is a carbon-carbon single bond or a formula:
—CH ₂ —O—CH ₂ —
X is an integer of 2 to 20, X is a group represented by the formula —SO ₃ M ¹ , and M ¹ is an alkali metal, ammonium group, or alkanolamine residue. . )

（式中、Ｒ^２２及びＲ^３２は、それぞれ独立して、水素原子又は炭素数１〜１２の炭化水素基であり、Ｄは、炭素−炭素単結合又は式：
−ＣＨ_２−Ｏ−ＣＨ_２−
で表される基であり、ｙは２〜２０の整数であり、Ｙは式−ＳＯ_３Ｍ^２で表される基であり、Ｍ^２はアルカリ金属、アンモニウム基、又はアルカノールアミン残基である。）
で表される化合物が好ましい。

(In the formula, R ²² and R ³² each independently represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms, and D represents a carbon-carbon single bond or a formula:
—CH ₂ —O—CH ₂ —
Y is an integer of 2 to 20, Y is a group represented by the formula —SO ₃ M ² , and M ² is an alkali metal, ammonium group, or alkanolamine residue. . )
The compound represented by these is preferable.

  Examples of the polymerizable surfactant represented by the general formula (1) include compounds described in JP-A-5-320276 or JP-A-10-316909. Examples of the preferred polymerizable surfactant represented by the general formula (1) include compounds represented by the following general formula (3), and more specifically, the following structural formulas (3a) to (3) Mention may be made of the compounds represented by 3d).

（式中、Ｒ^３１、ｘ、及びＭ^１は一般式（１）におけると同義である。）

(In the formula, R ³¹ , x, and M ¹ have the same meanings as in general formula (1).)

A commercial item can also be used as said anionic polymerizable surfactant. Examples of commercially available products include Aqualon HS series (Aqualon HS-05, HS-10, HS-20, and HS-1025) (trade names) manufactured by Daiichi Kogyo Seiyaku Co., Ltd., or Asahi Denka Kogyo Co., Ltd. Examples include Adeka Soap SE-10N and SE-20N (trade name) manufactured by the company.
In addition, Adeka Soap SE-10N of Asahi Denka Kogyo Co., Ltd. is a compound having M ¹ = NH ₄ , R ³¹ = C ₉ H ₁₉ and x = 10 in the general formula (3). Adekaria Soap SE-20N manufactured by Asahi Denka Kogyo Co., Ltd. is a compound having M ¹ = NH ₄ , R ³¹ = C ₉ H ₁₉ , and x = 20 in the general formula (3).

  In addition, as the anionic polymerizable surfactant used in the present invention, for example, a compound represented by the following general formula (4) is preferable, and among those represented by the general formula (4), a preferable anionic polymerizable interface is preferable. Examples of the activator include a compound represented by the following general formula (4a).

（式中、ｐは９又は１１であり、ｑは２〜２０の整数であり、Ａは−ＳＯ_３Ｍ^３で表わされる基であり、Ｍ^３はアルカリ金属、アンモニウム基又はアルカノールアミン残基である。）

(In the formula, p is 9 or 11, q is an integer of 2 to 20, A is a group represented by —SO ₃ M ³ , and M ³ is an alkali metal, ammonium group or alkanolamine residue. is there.)

（式中、ｒは９又は１１、ｓは５又は１０である。）

(In the formula, r is 9 or 11, and s is 5 or 10.)

  A commercial item can also be used as said anionic polymerizable surfactant. Examples of commercially available products include Aqualon KH series (trade names: Aqualon KH-5 and Aqualon KH-10) manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Aqualon KH-5 is a mixture of a compound of r = 9 and s = 5 and a compound of r = 11 and s = 5 in the general formula (4a).

  Moreover, as an anionic polymerizable surfactant used for this invention, the compound represented by following General formula (5) is also preferable.

（式中、Ｒ^４は水素原子又は炭素数１〜１２の炭化水素基を表し、ｌは２〜２０の整数を表し、Ｍ^４はアルカリ金属、アンモニウム基、又はアルカノールアミン残基を表す。）

(In the formula, R ⁴ represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms, 1 represents an integer of 2 to 20, and M ⁴ represents an alkali metal, an ammonium group, or an alkanolamine residue.)

（式中、Ｒ^１１，Ｒ^１２，Ｒ^１３，Ｒ^１４はそれぞれ独立して、水素原子又は炭素数１〜１８の炭化水素基であり、ｅ，ｆはそれぞれ独立して２〜２０の整数である。） Furthermore, as the anionic polymerizable surfactant used in the present invention, for example, a compound represented by the following general formula (6) is also preferably used.

(Wherein R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are each independently a hydrogen atom or a hydrocarbon group having 1 to 18 carbon atoms, and e and f are each independently an integer of 2 to 20) is there.)

  A commercial item can also be used as said anionic polymerizable surfactant. Examples of commercially available products include Antox MS-60 (trade name) manufactured by Nippon Emulsifier Co., Ltd.

  The anionic polymerizable surfactants exemplified above may be used alone or in combination of two or more. Moreover, it can also be used in combination with a nonionic polymerizable surfactant.

(Nonionic polymerizable surfactant)
The nonionic polymerizable surfactant used in the present invention is a compound having a nonionic group, a hydrophobic group, and a polymerizable group as a water-soluble group.
Specific examples of the nonionic polymerizable surfactant used in the present invention include nonionic allyl derivatives as described in JP-A-62-2104802, and JP-A-62-2100502. Nonionic propenyl derivatives, nonionic acrylic acid derivatives as described in JP-A-56-28208, nonionic itaconic acids as described in JP-B-59-12681 Derivatives, nonionic maleic acid derivatives as described in JP-A-59-74102, and the like.

  Nonionic polymerizable surfactants used in the present invention include, for example, polyoxyethylene alkyl ether having (meth) allyl group, (meth) acryloyl group, vinyl group, isopropenyl group and the like as reactive groups in the molecule. , Polyoxyethylene phenyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene aralkyl phenyl ether, and the like.

  The nonionic polymerizable surfactants exemplified above may be used alone or in combination of two or more. Further, it can be used in combination with either a cationic polymerizable surfactant or an anionic polymerizable surfactant.

(Polymerization initiator)
A part of the polymer constituting the microencapsulated wall material of the microencapsulated color material of the present invention is obtained by polymerizing at least one monomer component C as described above. This polymerization reaction can be carried out using a known polymerization initiator. That is, polymer B is added and mixed in an aqueous dispersion of colorant particles formed by adsorbing polymer A on the surface, and then at least one monomer component C and a polymerization initiator are mixed in this dispersion. Then, the surface of the color material particles is coated with an organic polymer (third step).
As this polymerization initiator, it is particularly preferable to use a radical polymerization initiator. As the polymerization initiator, either a water-soluble polymerization initiator or an oil-soluble polymerization initiator can be used.
When at least one monomer component selected from only a hydrophobic monomer and a polymerizable surfactant is used as the monomer component C, a polymerization initiator can be uniformly introduced into the monomer, so that oil-soluble polymerization starts. More preferably, an agent is used.

<Water-soluble polymerization initiator>
Examples of the water-soluble polymerization initiator include 2,2′-azobis (2-amidinopropane) dihydrochloride, 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis [2- (2-Imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrate, 2,2′-azobis [ N- (2-carboxyethyl) -2-methylpropionamide], 2,2′-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} dihydrochloride, 2, 2′-azobis (1-imino-1-pyrrolidino-2-methylpropane) dihydrochloride, 2,2′-azobis {2-methyl-N- [2- (1-hydroxybutyl)] propionamide}, 2 , 2′-azobis [2- (5-methyl-imida Zolin-2-yl) propane] dihydrochloride, 2,2′-azobis [2- (3,4,5,6, -tetrahydropyrimidin-2-yl) propane] dihydrochloride and other azo compound initiators Oxidizers such as potassium persulfate, sodium persulfate, ammonium persulfate and hydrogen peroxide alone, or these oxidants and sodium sulfite, sodium hyposulfite, ferrous sulfate, ferrous nitrate, sodium formaldehyde sulfoxylate, A redox initiator combined with a water-soluble reducing agent such as thiourea can be mentioned.

<Oil-soluble polymerization initiator>
Examples of oil-soluble polymerization initiators include 2,2′-azobisisobutyronitrile, 1,1′-azobiscyclohexane 1-carbonitrile, 2,2′-azobis-4-methoxy-2,4-dimethyl. Valeronitrile, 2,2′-azobis-2,4-dimethylvaleronitrile, dimethyl-2,2′-azobis (2-methylpropionate), 1,1′-azobis (1-acetoxy-1-phenylethane) ) And 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile) initiators; acetylcyclohexylsulfonyl peroxide, isobutyryl peroxide, diisopropyl peroxydicarbonate, di-2- Ethylhexyl peroxydicarbonate, 2,4-dichlorobenzoyl peroxide, t-butylperoxypivale , 3,5,5-trimethylhexanonyl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, stearoyl peroxide, propionitrile peroxide, succinic acid peroxide, acetyl peroxide, t -Butylperoxy-2-ethylhexanoate, benzoyl peroxide, parachlorobenzoyl peroxide, t-butylperoxyisobutyrate, t-butylperoxymaleic acid, t-butylperoxylaurate, cyclohexanone peroxide Oxide, t-butylperoxyisopropyl carbonate, 2,5-dimethyl-2,5-dibenzoylperoxyhexane, t-butylperoxyacetate, t-butylperoxyben Ate, diisobutyl diperoxyphthalate, methyl ethyl ketone peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexane, t-butylcumyl peroxide, t-butyl hydroperoxide, di peroxide polymerization initiators such as t-butyl peroxide, diisopropylbenzene hydroperoxide, paramentane hydroperoxide, pinane hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide and cumene peroxide; Oil-soluble peroxides such as hydroperoxides (tret-butylhydroxyperoxide, cumenehydroxyperoxide, etc.), dialkyl peroxides (such as lauroyl peroxide) and diacyl peroxides (benzoyl peroxide, etc.) And oil-soluble reducing agents such as tertiary amines (triethylamine, tributylamine, etc.), naphthenates, mercaptans (mercaptoethanol, lauryl mercaptan, etc.), organometallic compounds (triethylaluminum, triethylboron, diethylzinc, etc.) An oil-soluble redox polymerization initiator used in combination.

In the production of the microencapsulated color material of the present invention, for example, when a water non-dispersible pigment is used as a color material, and a polymer having a cationic group and a hydrophobic group is used as the polymer A adsorbed on the pigment particle surface, for example. If there is, first, an aqueous dispersion of pigment particles having the polymer A adsorbed on the surface thereof is prepared (first step), and polymer B having an anionic group is added thereto and mixed (second step). Here, the anionic group of the polymer B having an anionic group is ionically bonded to the cationic group on the surface of the pigment particle that has adsorbed the polymer A having a cationic group to be immobilized. Next, the monomer component C and the polymerization initiator are added and mixed to carry out emulsion polymerization (third step). In order to mix these raw materials well, it is preferable to irradiate the mixed dispersion with ultrasonic waves. In addition, when the polymer B which has an anionic group has a hydrophobic group, since it can encapsulate more monomers and can encapsulate with the highly uniform coating state, it is more preferable.
By such a procedure, the polymer A having a cationic group and a hydrophobic group, and the polymer B having an anionic group, a hydrophilic monomer, a hydrophobic monomer, an anionic polymerizable surfactant, a nonionic polymerizable interface A microencapsulated pigment coated with a polymer having a repeating structural unit derived from one or more monomer components C selected from the group consisting of active agents can be suitably produced.

  When at least one monomer component selected from only a hydrophobic monomer and a polymerizable surfactant is used as the monomer component C, the monomer component C and the oil-soluble polymerization initiator are previously homogenized in the third step. It is preferable to carry out emulsion polymerization after adding and mixing the solution. By homogenizing the monomer component C and the oil-soluble polymerization initiator in advance, the polymerization initiator is uniformly arranged in the monomer, the monomer is more uniformly polymerized, and the colorant particles are more uniformly coated with the polymer. It becomes possible.

[Raw material usage ratio]
In the first step, the amount of the polymer A adsorbed on the surface of the color material particles is preferably in the range of about 1 to 500% by weight with respect to the color material particles, more preferably 10 to 200. % By weight. If the amount of the polymer A is too small, the color material becomes unstable in dispersion in the aqueous medium and causes aggregation. In addition, the amount of polymer A adsorbed to the color material is limited by the hydrophilic-hydrophobic balance of polymer A, the total surface area of the color material particles, the affinity between the hydrophobic group and the color material particle surface, and the like. If the amount is too large, the amount of the free polymer A that is not adsorbed on the coloring material increases, which causes viscosity increase of the dispersion and dispersion instability.
In the first step, if the concentration of the coloring material particles in the aqueous medium is excessively high, the increase in viscosity becomes extremely difficult to disperse, and if the concentration is low, the dispersion efficiency is extremely decreased. It is preferable that it is about.

  In order to adsorb the polymer A on the surface of the color material particles, for example, a predetermined amount of the polymer A and the color material particles are dispersed in a water medium containing water as a main component using a general disperser. As the disperser used for the dispersion treatment, various dispersers that are generally used for pigment dispersion can be appropriately used. The disperser is not particularly limited, and a paint shaker, ball mill, sand mill, attritor, pearl mill, coball mill, homomixer, homogenizer, wet jet mill, ultrasonic homogenizer, and the like can be used. Glass beads, zirconia beads, alumina beads, magnetic beads, and styrene beads can be used for those using media as a disperser. Among these, a particularly preferable dispersion treatment prescription is a method in which beads are dispersed in a mill using a medium and then dispersed with an ultrasonic homogenizer.

A method for obtaining a colorant dispersion having a preferable particle diameter is not particularly limited, but the colorant in the dispersion liquid is used to reduce the size of the dispersion medium of the disperser and increase the filling rate of the dispersion medium. Various methods such as increasing the concentration, extending the processing time, and classifying with a filter, a centrifugal separator or the like after dispersion, or a combination of these methods are used as appropriate.
When an undesirable phenomenon such as thickening or foaming of the dispersion occurs due to heat generation during dispersion, it is desirable to perform the dispersion treatment while cooling.

In the second step, the amount of the polymer B added to the aqueous dispersion of the colorant particles adsorbed by the polymer A is such that the total number of dissociated ionic groups of the whole added polymer B is the surface of the colorant particles. The total number of dissociated ionic groups in the adsorbed polymer A is preferably more than 1 time, more preferably 2 times or more. When the amount of the polymer B is smaller than this, the coloring material becomes unstable in dispersion in the aqueous medium and causes aggregation. In addition, if the amount of polymer B is too large, the amount of free polymer B not adsorbed on the coloring material increases and causes the viscosity of the dispersion to increase and the dispersion to become unstable. It is preferable that the total number of groups is 10 times or less, particularly 7 times or less of the total amount of dissociated ionic groups of the entire polymer A adsorbed on the surface of the colorant particles.
The amount of polymer added is generally not limited to the total dissociation of ionic groups in the polymer, so it is preferable to define the total amount of ionic groups actually dissociated as described above. .

  In order to adsorb the polymer B to the color material particles adsorbed by the polymer A, for example, a predetermined amount of the polymer B may be added to the aqueous dispersion having the color material particles adsorbed by the polymer A and mixed. . Here, for mixing the polymer B into the aqueous dispersion, various apparatuses that are usually used for mixing the solution may be used, and the apparatus is not particularly limited, but a homomixer, a homogenizer, a wet jet is used. A mill, a magnetic stirrer, an ultrasonic disperser, or the like can be used. Among these, a particularly preferable treatment prescription includes an ultrasonic disperser.

  In the third step, the amount of the monomer component C added to the dispersion is 0.1 to 10 parts by weight, particularly 0.2 to 5 parts by weight with respect to 1 part by weight of the colorant particles. It is preferable. If the amount of the monomer component C added is too small, only a polymer having a low molecular weight is formed as the wall material, and the coating of the color material particles becomes incomplete, which is not preferable. On the other hand, if the amount of the monomer component C added is too large, a large number of polymer fine particles not containing colorant particles are generated, which causes an increase in viscosity of the dispersion, which is not preferable. By adding an appropriate amount of the monomer component C, the following admicelle is formed, and the desired microencapsulated color material of the present invention can be obtained by a subsequent polymerization reaction.

In the third step, it is preferable to irradiate the aqueous dispersion with ultrasonic waves also when the monomer component C is added to the aqueous dispersion and mixed.
When the polymer A has a cationic group, the polymer B having an anionic group is electrostatically adsorbed on the cationic group of the polymer A having a cationic group adsorbed on the surface of the pigment particle by the above-described process. When a hydrophobic monomer is added to the polymer, the hydrophobic monomer is further localized on the outer side, and the polymer B having an anionic group on the outer side thereof, an anionic monomer as a monomer component C, a nonionic monomer, an anionic polymerization 1 or 2 or more types selected from the group consisting of a surfactant and a nonionic polymerizable surfactant are oriented with their hydrophilic groups (anionic groups or nonionic groups) oriented toward the aqueous phase, and admicelles It is estimated that (admicell) is formed. In the case of using a polymer having an anionic group as the polymer A, a cationic monomer, a cationic polymerizable surfactant and a nonionic polymerizable surfactant are used as the monomer component C and the polymer B having a cationic group. It is preferable to use one or more selected from the group consisting of agents.

  In the polymerization reaction in the third step, when a microencapsulated color material having excellent dispersion stability in an aqueous medium can be obtained without irradiating the aqueous dispersion with ultrasonic waves, Ultrasonic irradiation is not always necessary.

  In the third step, the polymerization initiator may be added simultaneously with the monomer component C or may be added and mixed separately. Further, the polymerization initiator may be added or mixed all at once or divided into the aqueous dispersion formed with the above admicelle heated to a temperature at which the polymerization initiator is activated, or continuously added and mixed. May be. In the present invention, as described above, either a water-soluble polymerization initiator or an oil-soluble polymerization initiator can be used as the polymerization initiator. When using at least one monomer component selected from a hydrophobic monomer and a polymerizable surfactant as the monomer component C, the monomer component C and the oil-soluble polymerization initiator are homogenized in advance, and then the solution is added and mixed More preferably. The added polymerization initiator is cleaved to generate initiator radicals, which attack the polymerizable group of the polymerizable surfactant and the polymerizable group of the polymerizable monomer to cause a polymerization reaction.

Although the polymerization temperature and the polymerization reaction time vary depending on the type of polymerization initiator used and the type of polymerizable monomer, it is easy to appropriately set preferable polymerization conditions. In general, the polymerization temperature is preferably in the range of 40 ° C. to 90 ° C., and the polymerization time is preferably 3 hours to 12 hours.
Moreover, although the usage-amount of a polymerization initiator changes with kinds of polymerization initiator to be used, and the kind of polymerizable monomer, it is 0.0001-20 mol% normally with respect to a polymerizable monomer, Preferably it is 0.001-5 mol%. It is.

  In the polymerization reaction, monomer component C, that is, a polymerizable surfactant, a hydrophilic monomer, a hydrophobic monomer, a crosslinkable monomer, a compound represented by the general formula (7), and other known polymerizable monomers Can use 1 type (s) or 2 or more types, respectively. In the emulsion polymerization reaction, when a polymer having a hydrophilic group and a hydrophobic group is used, the emulsified state of the aqueous dispersion containing the raw material monomer is often good without using an emulsifier. Therefore, it is not always necessary to use an emulsifier, but at least one selected from the group consisting of known anionic, nonionic and cationic emulsifiers can be used as necessary.

  When the surface of the microencapsulated color material obtained by the polymerization reaction has an anionic group, the pH of the obtained aqueous dispersion is adjusted in the range of 7.0 to 9.0 after the polymerization is completed. It is preferable to perform filtration. This filtration is preferably ultrafiltration.

  According to the emulsion polymerization method described above, first, it is considered that the anionic polymer is adsorbed on the cationic group of the cationic polymer adsorbed on the surface of the colorant particle. Next, a polymerizable monomer and / or a polymerizable surfactant containing a hydrophobic monomer is added, and treatment is performed by irradiating ultrasonic waves. By this treatment, the arrangement form of the polymerizable surfactant and polymerizable monomer molecules present around the pigment particles is extremely highly controlled, and the outermost layer has a hydrophilic group (anionic group or nonionic group) toward the aqueous phase. ) Are oriented. Then, by emulsion polymerization of this aqueous dispersion, the monomer is polymerized into a polymer while the monomer molecules are highly controlled around the pigment particles, and the microencapsulated color material of the present invention is obtained. it is conceivable that. By using the emulsion polymerization method of the present invention, the production of water-soluble oligomers and polymers as by-products can be suppressed. Thereby, a low-viscosity microencapsulated color material dispersion can be obtained. With such a low-viscosity microencapsulated color material dispersion, a purification step such as ultrafiltration can be easily performed. In addition, the ink composition using the microencapsulated color material obtained by the polymerization method has excellent dispersion stability, excellent ejection stability from the recording head, hardly bleeds even on plain paper, and has high color development. A high density recorded image can be obtained.

  The microencapsulated color material of the present invention obtained as described above has high dispersion stability with respect to an aqueous solvent. This is because the color material particles are completely covered with the polymer layer (the uncoated part). This is considered to be because the hydrophilic groups in the polymer layer of the microcapsule wall material are regularly oriented toward the aqueous solvent.

  In the case of using the colorant particles having the polymer A having an anionic group adsorbed on the surface, the polymer B having a cationic group is used, and the monomer component C is a hydrophobic monomer, a cationic monomer, a water-soluble nonionic monomer, One type or two or more types selected from the group consisting of nonionic polymerizable surfactants and cationic polymerizable surfactants are used. Other raw materials such as a polymerization initiator, operations such as ultrasonic irradiation, polymerization conditions, and the like are the same as in the case of using pigment particles in which the polymer A having a cationic group is adsorbed on the surface.

  The microencapsulated color material of the present invention thus obtained has a form in which the surface of the color material particles is coated with a polymer which is also a microcapsule wall material. It is also possible to add an antioxidant, a plasticizer or the like to the polymer so that the additives are contained in the polymer. Known materials can be used as such antioxidants and plasticizers.

  The microencapsulated color material of the present invention thus obtained is coated on the polymer A on which the color material particles (core substance) are adsorbed on the color material surface with a microcapsule wall material mainly composed of a polymer. The polymer of the wall material is 2) a polymer B having an ionic group having a charge opposite to the ionic group of the polymer A adsorbed on the surface of the coloring material, and 3) a hydrophobic monomer, hydrophilic It includes a repeating structural unit derived from one or more selected from the group consisting of a polymerizable monomer and a polymerizable surfactant.

  The ratio of the polymer as the wall material to the microencapsulated colorant of the microencapsulated colorant of the present invention is preferably 10 to 1000% by weight, particularly 40 to 500% by weight. If the ratio of the polymer as the wall material to the color material is too small, the color material cannot be sufficiently coated, and if it is too large, the particle size of the microencapsulated color material will increase too much, so that the dispersion stability and dischargeability Cause a decline.

The particle size of the microencapsulated color material of the present invention is preferably 400 nm or less, more preferably 300 nm or less, and particularly preferably 10 to 200 nm. If the particle size of the microencapsulated color material is larger than this range, the dispersion stability and the dischargeability are lowered, and if it is smaller, the weather resistance of the color material is lowered.
The particle diameter of the microencapsulated color material can be measured using a commercially available laser Doppler particle size distribution analyzer. The particle diameter of the microencapsulated color material of the present invention is such that the reaction mixture is a mixture of ultrasonic waves in a predetermined irradiation condition (mainly the difference in irradiation energy, which can be controlled by, for example, frequency and irradiation time) before the start of the polymerization reaction. To the desired particle size by controlling the irradiation conditions when the reaction mixture is irradiated with ultrasonic waves, and the difference in whether or not the reaction mixture is irradiated with ultrasonic waves during the polymerization reaction. Can be controlled.

  The microencapsulated color material of the present invention produced as described above is obtained as an aqueous dispersion thereof, and a desired material can be further mixed with this to prepare the ink composition of the present invention. Prior to that, unreacted monomers (polymerizable compounds such as ionic polymerizable surfactants and reactive monomers) contained in the aqueous dispersion of the microencapsulated colorant are previously removed and purified before use. It is preferable. An image created by using the ink for inkjet recording using the microencapsulated color material of the present invention on plain paper by refining an aqueous dispersion containing the microencapsulated color material to reduce the concentration of the unreacted monomer. The (recorded material of the present invention) can have excellent saturation, a high printing density (printing density), and an effect of suppressing the occurrence of image bleeding. Further, an image obtained when this ink is used with a dedicated medium for ink-jet recording, particularly an ink-jet glossy medium, further has good glossiness.

The microencapsulated color material of the present invention can be used in an ink composition, and is particularly preferable as a color material used in an inkjet recording ink.
Next, an ink composition using the microencapsulated color material of the present invention will be described.

[Ink composition]
The ink composition of the present invention is an aqueous ink composition, and the microencapsulated color material of the present invention is dispersed and contained in an aqueous medium. The content of the microencapsulated color material in the ink composition is preferably 1 to 30% by weight, more preferably 3 to 20% by weight, based on the total weight of the ink composition. In particular, in order to obtain a high printing density and high color developability, the content of the microencapsulated color material is preferably 3 to 15% by weight.

  The solvent used in the ink composition of the present invention preferably contains water and a water-soluble organic solvent, and can further contain other components as desired.

  In order to impart water retention and wettability to the ink composition for ink jet recording, it is preferable to add a wetting agent comprising a high-boiling water-soluble organic solvent to the ink composition of the present invention. As such a high-boiling water-soluble organic solvent, a water-soluble organic solvent having a boiling point of 180 ° C. or higher is preferable.

Specific examples of the water-soluble organic solvent having a boiling point of 180 ° C. or higher that can be used in the present invention include ethylene glycol, propylene glycol, diethylene glycol, pentamethylene glycol, trimethylene glycol, 2-butene-1,4-diol, 2-ethyl-1,3-hexanediol, 2-methyl-2,4-pentanediol, tripropylene glycol, polyethylene glycol having a molecular weight of 2000 or less, 1,3-propylene glycol, isopropylene glycol, isobutylene glycol, glycerin, meso Mention may be made of erythritol and pentaerythritol.
The high boiling water-soluble organic solvent used in the present invention more preferably has a boiling point of 200 ° C. or higher.
One or more of these high-boiling water-soluble organic solvents can be used in the ink composition of the present invention.

  By adding a high-boiling water-soluble organic solvent to the ink composition, the fluidity and redispersibility can be maintained for a long time even when left in an open state (the ink composition is in contact with air at room temperature). Ink for ink jet recording can be obtained. Furthermore, since such an ink composition is less likely to be clogged with an inkjet nozzle during printing using an inkjet printer or upon restart after printing interruption, the ink composition has high ejection stability from the inkjet nozzle. Things are obtained.

  In particular, when glycerin is contained in the ink composition of the present invention, clogging of the ink jet nozzle when the ink composition is used for ink jet recording is less likely to occur, and the storage stability of the ink composition itself is further reduced. Can also be increased.

  The total content of the water-soluble organic solvents including these high-boiling water-soluble organic solvents is preferably about 10 to 50% by weight, more preferably 10 to 30% by weight with respect to the total weight of the ink composition. %.

The ink composition of the present invention further comprises 2-pyrrolidone, N-methylpyrrolidone, ε-caprolactam, dimethyl sulfoxide, sulfolane, morpholine, N-ethylmorpholine, 1,3-dimethyl-2-imidazolidinone, and the like. One or more polar solvents selected from the group can be added. By adding these polar solvents, the effect of improving the dispersibility of the microencapsulated color material in the ink composition can be obtained, and the ink ejection stability can be improved.
The content of these polar solvents is preferably 0.1 to 20% by weight, more preferably 1 to 10% by weight, based on the total weight of the ink composition.

  The ink composition of the present invention preferably further contains a penetrant for the purpose of promoting the penetration of the aqueous solvent into the recording medium. When the aqueous solvent quickly permeates the recording medium, a recorded matter with less image blur can be obtained.

  As such penetrants, polyhydric alcohol alkyl ethers (also referred to as glycol ethers) and / or 1,2-alkyldiols are preferably used. Examples of the alkyl ether of polyhydric alcohol include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, Ethylene glycol mono-iso-propyl ether, diethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol Mono-t-butyl ether, -Methyl-1-methoxybutanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, dipropylene glycol monomethyl ether , Dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-iso-propyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol mono-n-butyl ether, and the like. Examples of the 1,2-alkyldiol include 1,2-pentanediol and 1,2-hexanediol. In addition to these, straight-line such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, and 1,8-octanediol. Examples thereof include diols of chain hydrocarbons, which can be appropriately selected from these and used in the ink composition of the present invention.

  In particular, in the present invention, at least one selected from propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, 1,2-pentanediol, and 1,2-hexanediol penetrates. It is preferable to use it as an agent.

The content of these penetrants is preferably 1 to 20% by weight, more preferably 1 to 10% by weight, based on the total weight of the ink composition. By increasing the content of the penetrant to more than 1% by weight, the effect of improving the penetrability of the ink composition into the recording medium can be obtained, and by further reducing the content to 20% by weight or less, the ink composition can be used. Bleeding can be prevented from occurring in the printed image, and the viscosity of the ink composition can be prevented from becoming too high.
In particular, when a 1,2-alkyldiol such as 1,2-pentanediol or 1,2-hexanediol is used in the ink composition, the drying property of the ink composition after printing becomes good, and The bleeding of the image can be reduced.

  Further, when glycol ethers are used in the ink composition of the present invention, it is preferable to use an acetylene glycol surfactant described later together with the glycol ethers.

  The ink composition of the present invention preferably contains a surfactant, particularly an anionic surfactant and / or a nonionic surfactant. Specific examples of the anionic surfactant include alkane sulfonate, α-olefin sulfonate, alkyl benzene sulfonate, alkyl naphthalene sulfonic acid, acylmethyl tauric acid, dialkyl sulfosuccinic acid, alkyl sulfate ester salt, sulfate Oil, sulfated olefin, polyoxyethylene alkyl ether sulfate, fatty acid salt, alkyl sarcosine, alkyl phosphate, polyoxyethylene alkyl ether phosphate, monoglycerite phosphate, etc. It is done. Specific examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkyl amide, glycerin alkyl ester, sorbitan alkyl ester, sugar alkyl ester, And alkanolamine fatty acid amides.

  More specifically, examples of the anionic surfactant include sodium dodecylbenzenesulfonate, sodium laurate, and an ammonium salt of polyoxyethylene alkyl ether sulfate. Specific examples of the nonionic surfactant include polyoxyethylene. Ethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, and polyoxyalkylene alkyl ether Ether compounds such as polyoxyethylene oleic acid, polyoxyethylene oleate, polyoxyethylene distea Phosphate esters, sorbitan laurate, sorbitan monostearate, may be mentioned sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, and ester-based compounds such as polyoxyethylene stearate.

  In particular, the ink composition for ink jet recording according to the embodiment of the present invention preferably includes an acetylene glycol surfactant and / or an acetylene alcohol surfactant as a surfactant, and is thereby included in the ink composition. Since the aqueous solvent to be penetrated easily penetrates into the recording medium, it is possible to print an image with less bleeding on various recording media.

  Preferable specific examples of the acetylene glycol surfactant used in the present invention include compounds represented by the following general formula (8).

（式中、ｇ及びｈは、それぞれ０≦ｇ＋ｈ≦５０を満たす整数であり、Ｒ^１５、Ｒ^１６、Ｒ^１７及びＲ^１８は、それぞれ独立してアルキル基（好ましくは炭素数６以下のアルキル基）を表す。）

(In the formula, g and h are integers satisfying 0 ≦ g + h ≦ 50, respectively, and R ¹⁵ , R ¹⁶ , R ¹⁷ and R ¹⁸ are each independently an alkyl group (preferably an alkyl group having 6 or less carbon atoms). )

  Particularly preferable compounds represented by the general formula (8) include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6. -Diol, 3,5-dimethyl-1-hexyn-3-ol and the like. As the compound represented by the general formula (8), commercially available products available as acetylene glycol surfactants can be used. Specific examples include Surfynol 104, 82, 465, 485, And TG (both available from trade name, Air Products and Chemicals. Inc.), and Olphine STG and Olphine E1010 (above trade names, manufactured by Nisshin Chemical Co., Ltd.). Examples of the acetylene alcohol surfactant include Surfynol 61 (trade name, available from Air Products and Chemicals, Inc.).

  These acetylene glycol surfactants and / or acetylene alcohol surfactants are preferably in the range of 0.01 to 10% by weight, more preferably 0.1 to 5% by weight, based on the total weight of the ink composition. It is preferable to use so that it may become the range of%.

Polymer fine particles can be further added to the ink composition of the present invention. The polymer fine particles are preferably in the form of the following [1], particularly [2].
[1] Polymer fine particles having an ionic group on the surface and a volume average particle diameter of 10 to 200 nm.
[2] Polymer fine particles having an ionic group of the same type as that of the surface of the microencapsulated colorant of the present invention on the surface and having a volume average particle diameter of 10 to 200 nm.

  As described above, a microcapsule wall material mainly composed of a polymer having a repeating structural unit derived from a crosslinkable monomer and / or a polymer having a repeating structural unit derived from a monomer represented by the general formula (7) The microencapsulated color material coated with, has high mechanical strength, heat resistance, and solvent resistance, but the plasticity of the polymer becomes insufficient, and the fixability and heat resistance to the recording medium tend to decrease. It is in. However, even if the plasticity of the microcapsule wall material of the microencapsulated color material is insufficient, in combination with the polymer fine particles, an image formed on a recording medium using the obtained ink composition is microscopic. The encapsulated coloring material can be covered with the polymer fine particles, and the fixing property of the image to the recording medium and the abrasion resistance of the image can be increased.

  As the polymer fine particles, those having film-forming properties are particularly preferable. Here, “having film-forming properties” means that a polymer film can be formed when polymer fine particles are dispersed in water to form an aqueous emulsion and the water in the aqueous emulsion is evaporated. The ink composition of the present invention containing polymer fine particles having film-forming properties has a property of forming a polymer film when the solvent component is evaporated. By this polymer film, the microencapsulated pigment in the ink can be more firmly fixed to the surface of the recording medium. As a result, an image having better abrasion resistance and water resistance can be formed.

  In order for the polymer fine particles to have good film formability, the glass transition temperature of the polymer is preferably 30 ° C. or lower, more preferably 15 ° C. or lower, and particularly preferably 10 ° C. or lower. . The glass transition temperature of the polymer can be set within a preferable temperature range by appropriately selecting the type and composition ratio of the monomer to be used, and is a method well known to those skilled in the art. In the present invention, as the glass transition temperature of the polymer, the glass transition temperature obtained by temperature rise measurement using a thermal scanning calorimeter (DSC) was used. That is, in the differential heat curve obtained by measuring the temperature rise of the polymer with a thermal scanning calorimeter, when a tangent line is drawn from the bottom of the endothermic peak toward the end point of the endotherm, the intersection of the tangent line and the baseline Was the glass transition temperature (Tg) of the polymer.

  When the ink composition containing such polymer fine particles and the microencapsulated color material of the present invention is used for recording on a recording medium such as plain paper or a dedicated medium for inkjet recording, the aqueous medium in the ink composition is The polymer particles and the microencapsulated colorant particles penetrate into the recording medium, approach the polymer particles and / or the microencapsulated colorant particle coating polymers, and / or the polymer microparticles and the microencapsulated colorant particle coating polymer. A polymer film is formed on the recording medium in a state in which the colorant particles are fused and enclose the colorant particles inside. Thereby, the fixing property of the image to the recording medium and the abrasion resistance of the image can be particularly improved.

  Further, when the polymer fine particle has the same kind of ionic group as the microencapsulated color material on the surface, the polymer fine particle and the microencapsulated color material of the present invention may coexist in the ink composition. It is preferable because it can be stably dispersed without agglomeration.

  In particular, when the polymer fine particle and the microencapsulated color material of the present invention coexist in the ink composition, the ionic group of the polymer fine particle is the same kind as the ionic group on the surface of the microencapsulated color material particle of the present invention. If so, the dispersion stability of each particle in the ink composition can be made excellent.

  The particle diameter of the polymer fine particles is particularly preferably in the range of 50 to 200 nm in terms of volume average particle diameter. When the volume average particle diameter of the polymer fine particles exceeds 200 nm, the discharge of the ink composition from the inkjet nozzle tends to be unstable. When the volume average particle diameter of the polymer fine particles is less than 50 nm, the permeability of the polymer fine particles into the paper becomes high, and the above-described effects are hardly obtained.

The polymer fine particles preferably have a contact angle of 70 ° or more on the Teflon plate of an aqueous emulsion in which the fine particles are dispersed in an aqueous medium at a concentration of 10% by weight. Furthermore, the surface tension of an aqueous emulsion in which polymer fine particles are dispersed in an aqueous medium at a concentration of 35% by weight is preferably 40 × 10 ⁻³ N / m (40 dyne / cm, 20 ° C.) or more. By using the polymer fine particles having such characteristics, it is possible to more effectively prevent the flying curve of the ink droplets in the ink jet recording method, and it is possible to print an image with a good image quality.

  Further, by incorporating polymer fine particles having a relatively large amount of ionic groups on the surface as described above into the ink composition, better image abrasion resistance and water resistance can be realized. The reason is not clear, but it can be considered as follows. That is, when the ink composition of the present invention is attached to the surface of a recording medium such as paper, first, water and a water-soluble organic solvent in the ink composition penetrate into the recording medium. Then, the microencapsulated color material of the present invention and polymer fine particles remain in the vicinity of the surface of the recording medium. At this time, the ionic groups on the surface of the polymer fine particles act on the hydroxyl groups and carboxyl groups of cellulose constituting the paper fiber, and the polymer fine particles are firmly adsorbed on the paper fiber. The water and water-soluble organic solvent in the vicinity of the polymer fine particles adsorbed on the paper fibers further penetrate into the paper and decrease.

  Further, as described above, since the polymer fine particles have film-forming properties, when water and the water-soluble organic solvent disappear from the vicinity of the microencapsulated colorant and the polymer fine particles on the recording medium, the particles are united, A polymer layer is formed by encapsulating the encapsulated color material, and a state in which the color material particles are coated with the polymer is formed. This polymer can be more firmly bonded to the surface of the recording medium by an ionic group. However, these are hypotheses for explaining the effects of the present invention.

  The specific fine polymer particles are preferably composed of a polymer containing at least 1 to 10% by weight of a repeating unit derived from an unsaturated vinyl monomer having an ionic group. Furthermore, it has a structure in which a repeating unit derived from an unsaturated vinyl monomer having an ionic group is contained by 1 to 10% by weight and is cross-linked by a cross-linkable monomer having two or more polymerizable double bonds. It is more preferable that it is made of a polymer containing 0.2 to 4% by weight of a structure derived from this crosslinkable monomer. Crosslinkable monomers having two or more, and more preferably three or more, double bonds capable of polymerization during polymerization are copolymerized with other polymerizable monomers to crosslink the polymer chain, and such crosslinked polymers By using the polymer fine particles made of the above in the ink composition, the nozzle plate surface of the ink jet recording apparatus is further difficult to wet with the ink composition, so that it is possible to prevent the ink droplets from flying and to improve the ejection stability.

  As the polymer fine particles used in the ink composition of the present invention, those having a single particle structure having a uniform structure throughout the particles can be used, while the polymer fine particles having a core-shell structure comprising a core portion and a shell portion surrounding the core portion. Alternatively, polymer fine particles having a phase separation structure can be used. The “core-shell structure” includes not only a form in which the shell part completely covers the core part but also a part in which a part of the core part is covered. Further, a part of the shell polymer may form a domain or the like in the core particle. Furthermore, it may have a multilayer structure of three or more layers including layers having different compositions in the middle between the core part and the shell part.

  The polymer fine particles used in the present invention can be produced by a known emulsion polymerization method. For example, polymer fine particles can be obtained by emulsion polymerization of an unsaturated vinyl monomer (unsaturated vinyl monomer) in water containing a polymerization initiator and an emulsifier.

  Examples of the unsaturated vinyl monomer include acrylic acid ester monomers, methacrylic acid ester monomers, aromatic vinyl monomers, vinyl ester monomers, vinyls generally used in emulsion polymerization. Examples include cyanide monomers, halogenated monomers, olefin monomers, and diene monomers. Further, specific examples include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, decyl acrylate, dodecyl acrylate. Acrylic acid esters such as octadecyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, and glycidyl acrylate; methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n- Hexyl methacrylate, 2- Methacrylic acid esters such as tilhexyl methacrylate, octyl methacrylate, decyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, and glycidyl methacrylate; vinyl esters such as vinyl acetate; vinyl such as acrylonitrile and methacrylonitrile Cyanogen compounds; halogenated monomers such as vinylidene chloride and vinyl chloride; aromatic vinyl monomers such as styrene, 2-methylstyrene, vinyltoluene, t-butylstyrene, chlorostyrene, vinylanisole, and vinylnaphthalene Olefins such as ethylene, propylene, and isopropylene; dienes such as butadiene and chloroprene; and vinyl Ethers, vinyl ketones, and vinyl monomers such as vinyl pyrrolidone.

  Examples of the unsaturated vinyl monomer having an ionic group include unsaturated vinyl monomers having an anionic group selected from a sulfonic acid group, a sulfinic acid group, a carboxyl group, a carbonyl group, and salts thereof. Specifically, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and maleic acid, sodium vinyl sulfonate, 2-sulfoethyl methacrylate, and 2-acrylamido-2-methylpropane sulfonic acid Etc. can be illustrated. Further, dimethylaminoethyl methyl chloride salt, dimethylaminoethyl benzyl methacrylate salt, methacryloyloxyethyltrimethylammonium chloride salt, diallyldimethylammonium chloride salt, 2-hydroxy-3-methacryloxypropyltrimethylammonium chloride salt, etc. An unsaturated vinyl monomer having a cationic group can also be exemplified.

  Further, in addition to the above monomers, polymer fine particles produced using acrylamides or hydroxyl group-containing vinyl monomers are used in the ink composition, so that when this ink composition is used in an ink jet recording method, ink jet recording is performed. The ejection stability of the ink composition from the head can be improved. Examples of the acrylamides include acrylamide and N, N′-dimethylacrylamide. Examples of the hydroxyl group-containing vinyl monomer include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate, and one or more of these are used. be able to.

  As described above, the polymer constituting the polymer fine particle is preferably a polymer having a structure in which the structural unit derived from the monomer is cross-linked by a cross-linkable monomer having two or more polymerizable double bonds. . Examples of the crosslinkable monomer having two or more polymerizable double bonds include polyethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,6-butylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, 1,9-nonanediol diacrylate, polypropylene glycol diacrylate, 2,2′-bis (4-acryloxypropyroxyphenyl) propane, and 2,2 Diacrylate compounds such as' -bis (4-acryloxydiethoxyphenyl) propane; Triacrylates such as trimethylolpropane triacrylate, trimethylolethane triacrylate, and tetramethylolmethane triacrylate Tetraacrylate compounds such as ditrimethylol tetraacrylate, tetramethylol methane tetraacrylate, and pentaerythritol tetraacrylate; hexaacrylate compounds such as dipentaerythritol hexaacrylate; ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate Polyethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, Polybutylene glycol dimeta Relate and dimethacrylate compounds such as 2,2′-bis (4-methacryloxydiethoxyphenyl) propane; trimethacrylate compounds such as trimethylolpropane trimethacrylate and trimethylolethane trimethacrylate; methylenebisacrylamide; and divinyl Benzene is mentioned.

The core-shell structured polymer fine particles can be produced by a known method, but can be generally produced by multi-stage emulsion polymerization or the like. For example, it can be produced by the method disclosed in JP-A-4-76004. Examples of the unsaturated vinyl monomer used for the production of the core-shell structured polymer fine particles include the same unsaturated vinyl monomers as described above.
In addition, a polymerization initiator, a surfactant, a molecular weight adjusting agent, a neutralizing agent, and the like used when polymer fine particles are emulsion-polymerized can also be used in accordance with the known method.

  The ink composition of the present invention can contain a pH adjuster. When the colorant particle or polymer particle surface has an anionic group, the pH of the ink composition is preferably adjusted to 7 to 11, more preferably 8 to 9, and a basic compound is used as the pH adjuster. It is preferable. Further, when the colorant particle or polymer particle surface has a cationic group, it is preferable to adjust the pH of the ink composition to 5 to 7, more preferably 6 to 7, and an acidic compound is used as the pH adjuster. It is preferable to use it.

Specific preferred basic compounds as pH adjusters are sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, lithium carbonate, sodium phosphate, potassium phosphate, lithium phosphate. Alkali metal salts such as potassium dihydrogen phosphate, dipotassium hydrogen phosphate, sodium oxalate, potassium oxalate, lithium oxalate, sodium borate, sodium tetraborate, potassium hydrogen phthalate, and potassium hydrogen tartrate; ammonia As well as methylamine, ethylamine, diethylamine, trimethylamine, triethylamine, tris (hydroxymethyl) aminomethane hydrochloride, triethanolamine, diethanolamine, diethylethanolamine, triisopropenolamine, butyrate Diethanolamine, morpholine, and the like amines such as propanolamine.
Among these, when an alkali hydroxide compound or an amine alcohol is added to the ink composition, the dispersion stability of the pigment particles having an anionic group in the ink can be improved.

Also, for the purpose of mold prevention, antiseptic or rust prevention, benzoic acid, dichlorophen, hexachlorophene, sorbic acid, p-hydroxybenzoic acid ester, ethylenediaminetetraacetic acid (EDTA), sodium dehydroacetate, 1,2-benchazoline One or more compounds selected from -3-one [product name: Proxel XL (manufactured by Avicia)] and 3,4-isothiazolin-3-one, 4,4-dimethyloxazolidine, and the like are used in the ink composition of the present invention. Can be added.
In addition, at least one selected from the group consisting of urea, thiourea, and ethylene urea can be added to the ink composition of the present invention for the purpose of preventing the nozzles of the inkjet recording head from drying.

An example of a particularly preferred embodiment of the ink composition of the present invention comprises the following components (1) to (5).
(1) Microencapsulated coloring material of the present invention (2) One or more compounds selected from the group consisting of diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, and 1,2-alkyldiol having 4 to 10 carbon atoms ( Penetrant)
(3) Acetylene glycol surfactant and / or acetylene alcohol surfactant (4) Glycerin (5) Water

  In the above embodiment, when diethylene glycol monobutyl ether and / or triethylene glycol monobutyl ether of (2) is used as a penetrant, the amount added is 10% by weight or less based on the total weight of the ink composition. Preferably, it is 0.5 to 5% by weight. By adding diethylene glycol monobutyl ether and / or triethylene glycol monobutyl ether to the ink composition, the penetrability of the ink composition into the recording medium can be improved, which is effective in improving the print quality. Further, diethylene glycol monobutyl ether and / or triethylene glycol monobutyl ether also has an effect of improving the solubility of the acetylene glycol surfactant.

In the above embodiment, when the 1,2-alkyldiol having 4 to 10 carbon atoms of (2) is used as the penetrant, the amount added is 15% by weight or less based on the total weight of the ink composition. It is preferable. When a 1,2-alkyldiol having 3 or less carbon atoms is used, sufficient penetrability of the ink composition with respect to the recording medium cannot be obtained, and 1,2-alkyldiol having more than 15 carbon atoms in water. It is not preferred because it is difficult to dissolve.
If the amount of 1,2-alkyldiol in the ink composition exceeds 15% by weight, the viscosity of the ink composition tends to increase, such being undesirable.
Specifically, 1,2-pentanediol or 1,2-hexanediol is preferably used as the 1,2-alkyldiol, and either one can be used alone or both can be used in combination. 1,2-pentanediol is preferably added in an amount of 3 to 15% by weight based on the total weight of the ink composition. By adding 3% by weight or more of 1,2-pentanediol to the ink composition, an ink composition having good permeability can be obtained. 1,2-hexanediol is preferably added in a range of 0.5 to 10% by weight with respect to the total weight of the ink composition, and an ink composition having good permeability can be obtained in this range.

  In addition, when the ink composition of the above embodiment is used in an ink jet recording method, a solid wetting agent is added to the ink composition so that clogging of the ink jet nozzle is less likely to occur (in order to improve clogging reliability). It is preferable to make it contain in the ratio of 3-20 weight% with respect to the total weight. The addition of the solid humectant is not limited to the above embodiment example, and can be added to the ink composition using the microencapsulated color material of the present invention.

The solid wetting agent refers to a water-soluble substance that is solid at room temperature (25 ° C.) and has a water retention function. Preferred solid wetting agents are saccharides, sugar alcohols, hyaluronate, trimethylolpropane, and 1,2,6-hexanetriol. Examples of sugars include monosaccharides, disaccharides, oligosaccharides (including trisaccharides and tetrasaccharides) and polysaccharides, preferably glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glucitol. Sorbitol, maltose, cellobiose, lactose, sucrose, trehalose, maltotriose and the like. Here, saccharide means saccharide in a broad sense, and is used to include substances that exist widely in nature, such as alginic acid, α-cyclodextrin, and cellulose. The derivatives of these saccharides are represented by reducing sugars of the saccharides (for example, sugar alcohol (general formula HOCH ₂ (CHOH) _k CH ₂ OH (where k represents an integer of 2 to 5)). ), Oxidized sugars (eg, aldonic acid, uronic acid, etc.), amino acids, thio sugars, etc.). Of these, sugar alcohols are particularly preferred, and specific examples include maltitol, sorbitol, and xylitol. As the hyaluronate, a commercially available sodium hyaluronate 1% aqueous solution (molecular weight 350,000) can be used. Particularly preferred solid wetting agents are trimethylolpropane, 1,2,6-hexatriol, sugars, and sugar alcohols. One or more of these solid wetting agents can be added to the ink composition of the present invention.

  By using a solid wetting agent in the ink composition, it is possible to suppress the evaporation of the moisture of the ink by its water retention function, so that the viscosity of the ink composition does not increase around the ink composition flow path of the ink jet printer or around the ink jet nozzle. In addition, since the formation of a film due to the evaporation of water in the ink composition is less likely to occur, nozzle clogging is less likely to occur. Further, since the solid wetting agent is chemically stable, the quality of the ink composition can be maintained over a long period of time without being decomposed in the ink composition. Even when the solid wetting agent is added to the ink composition, the ink composition does not wet the nozzle plate, and the ink composition can be stably discharged from the inkjet nozzle. When the compound selected from trimethylolpropane, 1,2,6-hexanetriol, saccharides, and sugar alcohols is used as the solid moisturizing agent, the above-described effect is particularly excellent.

  The total amount of the solid wetting agent added to the ink composition of the present invention is preferably 3 to 20% by weight, and preferably 3 to 10% by weight, based on the total weight of the ink composition. More preferably. A preferred combination in the case of using a mixture of two or more solid wetting agents is selected from one or more selected from saccharides, sugar alcohols, and hyaluronic acid salts, trimethylolpropane, and 1,2,6-hexanetriol. It is a combination with one or more types. When a solid wetting agent is added to the ink composition in this combination, an increase in the viscosity of the ink composition can be suppressed. By making the amount of the solid wetting agent contained in the ink composition 3% by weight or more, an effect of preventing clogging of the ink jet nozzle is obtained, and the amount of the solid wetting agent contained in the ink composition is 20% by weight. % Or less, the ink composition can be stably ejected from the ink jet nozzle, so that an ink composition having a sufficiently low viscosity can be obtained.

In the above embodiment, the acetylene glycol surfactant and / or acetylene alcohol surfactant (3) is added to the ink composition, and the total amount of these surfactants is the total weight of the ink composition. The content is preferably 0.01 to 10% by weight, particularly preferably 0.1 to 5% by weight.
In addition, the content of (1) the microencapsulated coloring material of the present invention in the ink composition is preferably 0.1 to 30% by weight, particularly preferably 1 to 20% by weight, and (4) the content of glycerin. Is preferably 1 to 30% by weight, more preferably 5 to 25% by weight.

  The ink compositions shown in the above embodiment examples are particularly excellent in the dispersion stability of the coloring material and the ejection stability from the ink jet head nozzle when used in the ink jet recording method, and further, the nozzle clogging over a long period of time. Therefore, stable printing is possible. In addition, when the ink composition is printed on a recording medium such as plain paper, recycled paper, and coated paper, the drying property of the ink after printing is good, and there is no bleeding by using this ink composition. A high-quality image having a high printing density and excellent color developability can be obtained.

The ink jet recording method of the present invention is a method in which droplets of the above-described ink composition of the present invention are ejected from an ink jet head, and the droplets are attached to a recording medium. The recorded matter of the present invention can be obtained by recording on a print medium.
As described above, the present invention has been described. However, between the ink composition of the present invention prepared using the microencapsulated color material of the present invention and the ink composition prepared using a conventionally known color material, the following There are differences.

  A pigment dispersion in which a pigment is dispersed using a dispersant such as a surfactant or a polymer dispersant, and penetration of the acetylene glycol surfactant and / or acetylene alcohol surfactant and diethylene glycol monobutyl ether The ink composition using the agent is easily ejected from the pigment surface due to the strong shearing force applied when ejected through a thin inkjet nozzle, resulting in deterioration of dispersibility, and unstable ejection. Tend to be. On the other hand, in the ink composition of the present invention, such a phenomenon is not recognized at all, and the ink composition can be stably ejected through an inkjet nozzle for a long period of time. Further, since the microencapsulated color material particles of the present invention have good solvent resistance, the penetrant may cause the polymer of the microcapsule wall material to be detached from the surface of the color material particles or the polymer to swell. It is difficult to keep the color material particles stably dispersed in the ink composition over a long period of time.

  In addition, in a known ink composition that uses a pigment dispersion obtained by dispersing a pigment using a dispersant such as a surfactant or a polymer dispersant and has improved penetrability, the pigment is generally dispersed in the dispersion. Since not all of the dispersant is initially adsorbed on the pigment surface when dispersed in the medium, the viscosity of the ink composition tends to increase due to the dispersant dissolved in the pigment dispersion, As the time elapses, the dispersant is desorbed from the pigment, and the viscosity of the ink composition tends to increase due to the desorbed dispersant. For this reason, there are many cases where the content of the pigment contained in the pigment dispersion cannot be increased. When an ink composition using a pigment dispersion with a low pigment content is used, particularly when printing on plain paper or recycled paper, a sufficient print density cannot be obtained, and good color development of images can be obtained. Often not. On the other hand, in the ink composition using the microencapsulated color material of the present invention, the viscosity of the ink composition is hardly increased over time. Accordingly, the ink composition using the microencapsulated color material of the present invention has the advantages that it is easy to lower the viscosity and can contain more color material particles, and plain paper or recycled paper is used as a printing medium. Even in such a case, a sufficiently high printing density can be obtained.

  The ink composition of the present invention is preferably prepared such that the viscosity measured by the measurement method described in the Examples section below is 1 to 10 cP, particularly 1.5 to 5 cP. If the viscosity is too high, the discharge performance is lowered, and if it is too low, it becomes difficult to control the image formation on the paper.

[Microencapsulated product]
Next, the microencapsulated product of the present invention will be described.
The microencapsulated material of the present invention is the same as the above-described microencapsulated colorant of the present invention except that the drug substance, inorganic compound, metal powder, ceramics, organic compound, and polymer are used as the core material instead of the color material particles. Can be manufactured.
In the microencapsulated product of the present invention produced as described above, when the core substance is a drug substance, the encapsulated product of the drug substance can be a delayed-acting drug, and the core substance is an inorganic compound. The encapsulated materials are each useful as inorganic-organic hybrid (composite) particles. In addition, the microencapsulated polymer particles are useful as composite polymer particles, and these can be hybridized by using polymers having different physical properties as the core material. By encapsulating, a liquid material can be pulverized.

  Hereinafter, the present invention will be described more specifically with reference to examples.

[Synthesis Example 1]: Cationic Copolymer I; Synthesis of Poly (styrene-co-2-methacryloyloxyethyltrimethylammonium chloride) As a solvent, 13.9 g of 2,2′-azobisisobutyronitrile was added and “Solmix A-11” (mixture of ethanol / methanol / isopropyl alcohol = 85.5 / 13.4 / 1.1 was used as a solvent. Solvent, manufactured by Nippon Alcohol Sales Co., Ltd.) 2200.0 g, distilled water 330.0 g, monomer as styrene 415.0 g, “acrylic ester DMC” (80% aqueous solution of 2-methacryloyloxyethyltrimethylammonium chloride, manufactured by Mitsubishi Rayon Co., Ltd.) 442.0 g of lath as chain transfer agent Lil mercaptan 35.1g, were charged in the flask, respectively. This separable flask was immersed in an oil bath, the bath temperature was raised from room temperature to 78 ° C. over 1 hour, and polymerization was carried out at 78 ° C. for 10 hours.

  After the completion of the polymerization, the polymerization solution was concentrated under reduced pressure using an evaporator, and then the polymer formed by dropping the concentrated polymerization solution in an isopropanol / tetrahydrofuran (1/2: v / v) mixed solvent was precipitated. The supernatant was removed by decantation, 5000.0 g of distilled water was added and mixed, and then the residual organic solvent was removed by atmospheric distillation to obtain an aqueous polymer solution. The obtained aqueous polymer solution was dried to obtain poly (styrene-co-2-methacryloyloxyethyltrimethylammonium chloride): cationic copolymer I.

The structure of the copolymer was confirmed by ¹ H-NMR using DMSO (dimethyl sulfoxide) as a solvent. The composition ratio of the styrene unit and 2-methacryloyloxyethyltrimethylammonium chloride unit in the copolymer, determined by ¹ H-NMR, was 70:30 (molar ratio). Moreover, the number average molecular weight (Mn) measured by GPC (gel permeation chromatography) was 13000, and molecular weight distribution was 1.6.

[Production Example 1]: Preparation of cationic copolymer I black pigment dispersion (dispersion α) 28.0 g of black pigment (Mitsubishi Chemical Corporation: carbon black # 960), aqueous solution of cationic copolymer I obtained in Synthesis Example 1 (Solid content 20.57% by weight) 81.7 g and 170.0 g of distilled water were mixed, and 0.5 mmφ zirconia beads were used as media to disperse at 25 ° C. for 4 hours to remove the beads. Thereafter, a dispersion I was obtained by adjusting the pigment concentration to 8% by weight.
This dispersion I is put into a 500 mL tall beaker, the beaker is immersed in ice water, and dispersed for 40 minutes with an ultrasonic homogenizer (Nippon Seiki Seisakusho; US-600T; chip used 36 mmφ) to obtain pigment dispersion II. It was.
Distilled water was added to the dispersion II to dilute it twice, and then the free polymer was removed by ultrafiltration, followed by concentration to obtain a dispersion α having a pigment concentration of 8% by weight.

<Chlorine ion concentration measurement>
A liquid prepared by mixing 0.20 g of an ionic strength adjusting agent (Thermo Electron Corporation: Cat. No. 940011) with 10.0 g of a dispersion α10-fold diluted with distilled water was prepared. A chlorine composite electrode (Thermo Electron Corporation: model 9617) was attached to the sample, and the chlorine ion concentration was measured.
The obtained chlorine ion concentration was 0.044 mol / L.

[Synthesis Example 2]: Random Copolymer I; Synthesis of poly (sodium acrylate-co-n-butyl acrylate-co-styrene) To a condenser with a nitrogen-substituted interior, a nitrogen introduction tube, a stirrer and a thermometer , 30 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was charged as a catalyst, 3500.0 g of tetrahydrofuran as a solvent, 600.0 g of acrylic acid as a monomer, 600.0 g of n-butyl acrylate, and 400.0 g of styrene. , Each was charged into the above flask. This flask was immersed in an oil bath, the bath temperature was raised from room temperature to 70 ° C. over 1 hour, and a polymerization reaction was performed at 70 ° C. for 8 hours.

  After completion of the reaction, the reaction solution was cooled to room temperature, neutralized with a sodium hydroxide / methanol solution, and then poured into isopropyl alcohol to form a precipitate. The precipitate was filtered and vacuum dried to obtain a mixture of poly (sodium acrylate-co-n-butyl acrylate-co-styrene) and sodium acrylate.

  The number average molecular weight (Mn) measured by GPC of this polymer was 11000, and the molecular weight distribution was 1.6.

After dissolving 30.0 g of the random copolymer and sodium acrylate mixture in 970.0 g of water, sodium acrylate was removed by ultrafiltration. After removing the sodium acrylate, the polymer aqueous solution was concentrated and dried to obtain the random copolymer I.
The structure of this random copolymer I was confirmed by ¹ H-NMR using heavy water as a solvent. The composition ratio of the sodium acrylate unit, n-butyl acrylate unit, and styrene unit in the random copolymer I determined by ¹ H-NMR was 47:21:32 (molar ratio).

<Measurement of sodium ion concentration of random copolymer I>
A solution obtained by mixing 1 g of an ionic strength adjusting agent (Thermo Orion Corporation: Cat. No. 841111) with 10.0 g of a solution obtained by diluting a random copolymer I aqueous solution (13.6 wt%) 10 times with distilled water, A sodium composite electrode (Thermo Orion Corporation: Model 8611BN ROSS (registered trademark)) was attached to an ion meter (Thermo Orion Corporation: Model 290Aplus), and the sodium ion concentration was measured.
The value of the obtained sodium ion concentration was 0.49 mol / L.

[Production Example 2]: Preparation of microencapsulated black pigment dispersion (dispersion A) 276.3 g of an aqueous solution (13.6 wt%) of random copolymer I obtained in Synthesis Example 2 was diluted with 181.6 g of distilled water. The aqueous solution was added dropwise to a dispersion obtained by adding 266.7 g of distilled water to 300.0 g of the dispersion α, while stirring with a stirrer, and subjected to ultrasonic irradiation with an ultrasonic cleaner (“5510J-DTH” manufactured by BRANSONIC) for 30 minutes. Thereafter, stirring with a stirrer was further performed for 10 minutes to obtain dispersion A ′.

  Styrene monomer 37.2 g, crosslinker light ester TMP (trimethylolpropane trimethacrylate, Kyoeisha Chemical Co., Ltd.) 0.39 g, initiator V-65 (2,2′-azobis (2,4-dimethylvaleronitrile), Wako Pure Chemical Industries, Ltd.) 0.97 g was mixed to form a homogeneous solution, and 12.6 g of this solution was stirred into a dispersion obtained by diluting 450.0 g of dispersion A ′ with 59.7 g of distilled water while stirring with a stirrer. The mixture was gradually added dropwise, and stirring was continued for 30 minutes after completion of the addition. This was subjected to ultrasonic irradiation with an ultrasonic cleaner (BRANSONIC 5510J-DTH) for 30 minutes, and then treated with an ultrasonic disperser (“ULTRASONIC HOMOGENIZER UH-600” manufactured by SMT) for 5 minutes under ice cooling, Stirring was further performed for 1 hour. Thereafter, the flask was transferred to a 1 L four-necked flask equipped with a stirrer, a cooler, and a thermometer, and polymerized at 60 ° C. for 6 hours under a nitrogen stream while stirring at 250 rpm. After the polymerization is completed, ultrafiltration removes free random copolymers and excess ions in the aqueous phase, and after further concentration, the pH is adjusted to 8 with an aqueous sodium hydroxide solution, and the pigment concentration is 8% by weight. Liquid A was obtained.

[Production Example 3]: Preparation of microencapsulated black pigment dispersion (dispersion B) Styrene monomer 16.9 g, crosslinker light ester TMP (Kyoeisha Chemical Co., Ltd.) 0.18 g, initiator V-65 (Wako Pure) Yaku Kogyo Co., Ltd.) 0.90 g was mixed to form a homogeneous solution, and 8.7 g of the solution was added to the reactive surfactant Aqualon HS-10 (Daiichi Kogyo Seiyaku Co., Ltd., polyoxyethylene alkylpropenyl phenyl ether). (Sulfuric ester ammonium salt) was added dropwise to 88.8 g of a solution diluted with distilled water to 4.5% by weight and stirred with a stirrer for 10 minutes. This was treated with an ultrasonic disperser (“ULTRASONIC HOMOGENIZER UH-600” manufactured by SMT) for 10 minutes under ice cooling to prepare an emulsion.

  78.1 g of an aqueous solution (13.6% by weight) of the random copolymer I obtained in Synthesis Example 2 was added dropwise to the dispersion α160.0 g while stirring with a starter, and then for 30 minutes with an ultrasonic cleaner (BRANSONIC 5510J-DTH). Ultrasonic irradiation. Further, 94.7 g of the previous emulsion was dropped while stirring with a stirrer, and the mixture was again treated with an ultrasonic cleaner for 30 minutes.

  The obtained dispersion was transferred to a 1 L four-necked flask equipped with a stirrer, a cooler, and a thermometer, and polymerized at 60 ° C. for 6 hours under a nitrogen stream while stirring at 250 rpm. After the polymerization is completed, ultrafiltration removes free random copolymers and excess ions in the aqueous phase, and after further concentration, the pH is adjusted to 8 with an aqueous sodium hydroxide solution, and the pigment concentration is 8% by weight. Liquid B was obtained.

[Production Example 4]: Preparation of Cationic Copolymer I Black Pigment Dispersion (Dispersion β) Except for using # 47 (Mitsubishi Chemical Corporation) instead of # 960 (Mitsubishi Chemical Corporation) as carbon black. In the same manner as in Production Example 1, a dispersion β was obtained.
As a result of measuring the chlorine ion concentration by the same method as the dispersion α, a value of 0.037 mol / L was obtained.

[Production Example 5]: Preparation of microencapsulated black pigment dispersion (dispersion C) 14.1 g of styrene monomer, 0.15 g of crosslinker light ester TMP (Kyoeisha Chemical Co., Ltd.), initiator V-65 (Wako Pure) 6. 0.75 g of Yakuhin Kogyo Co., Ltd. is mixed to form a uniform solution, and 4.5 g of the solution is added to the reactive surfactant Aqualon HS-10 (Daiichi Kogyo Seiyaku Co., Ltd.) with distilled water. The solution was added dropwise to 45.8 g diluted to 4% by weight and stirred with a stirrer for 10 minutes. This was treated with an ultrasonic disperser (“ULTRASONIC HOMOGENIZER UH-600” manufactured by SMT) for 10 minutes under ice cooling to prepare an emulsion.

  An aqueous solution diluted by adding 2.1 g of distilled water to 30.6 g of the aqueous solution (13.6 wt%) of the random copolymer I obtained in Synthesis Example 2 was added dropwise to the dispersion β80.0 g while stirring with a stirrer. Ultrasonic irradiation was performed for 5 minutes with an ultrasonic cleaner (“5510J-DTH” manufactured by BRANSONIC). Further, while stirring with a stirrer, 47.3 g of the previous emulsion was dropped, and the mixture was again treated with an ultrasonic cleaner for 30 minutes.

  The obtained dispersion was transferred to a 1 L four-necked flask equipped with a stirrer, a cooler, and a thermometer, and polymerized at 60 ° C. for 6 hours under a nitrogen stream while stirring at 250 rpm. After the polymerization is completed, the free random copolymer in the aqueous phase and excess ions are removed by ultrafiltration. After further concentration, the pH is adjusted to 8 with an aqueous sodium hydroxide solution, and the pigment concentration is 8% by weight. Liquid C was obtained.

[Production Example 6]: Preparation of microencapsulated black pigment dispersion (dispersion D) trifluoroethyl methacrylate (light ester M-3F (Kyoeisha Chemical Co., Ltd.) 9.4 g), crosslinker light ester TMP (Kyoeisha Chemical ( Co.) 0.10 g and initiator V-65 (Wako Pure Chemical Industries, Ltd.) 0.50 g were mixed to form a homogeneous solution, and 4.5 g of the solution was obtained as a random copolymer I obtained in Synthesis Example 2. An aqueous solution (13.6 wt%) of 33.2 g was added dropwise to an aqueous solution diluted with 12.5 g of distilled water, and stirred for 10 minutes with an ultrasonic disperser (“Ultrasonic Homogenizer UH-600” manufactured by SMT). ) To prepare an emulsion by treatment for 10 minutes under ice cooling.

36.0 g of random copolymer I aqueous solution (13.6% by weight) was added dropwise to the dispersion α80.0 g while stirring with a stirrer, and was subjected to ultrasonic irradiation with an ultrasonic cleaner (BRANSONIC 5510J-DTH) for 30 minutes. Further, while stirring with a stirrer, 47.3 g of the previous emulsion was dropped, and the mixture was again treated with an ultrasonic cleaner for 30 minutes.
The obtained dispersion was transferred to a four-necked flask having an internal volume of 200 mL equipped with a stirrer, a cooler, and a thermometer, and polymerized at 60 ° C. for 6 hours under a nitrogen stream while stirring at 250 rpm. After the polymerization is completed, the free random copolymer in the aqueous phase and excess ions are removed by ultrafiltration. After further concentration, the pH is adjusted to 8 with an aqueous sodium hydroxide solution, and the pigment concentration is 8% by weight. Liquid D was obtained.

[Synthesis Example 3]: Random Copolymer II; Synthesis of poly (sodium acrylate-co-2-ethylhexyl acrylate) In a flask equipped with a nitrogen-substituted condenser, a nitrogen introduction tube, a stirrer and a thermometer, 2, '-Asobis (2,4-dimethylvaleronitrile) 5.5 g was charged, and further, 547.0 g of tetrahydrofuran as a solvent, 156.0 g of acrylic acid as a monomer, and 244.0 g of 2-ethylhexyl acrylate were charged into the flask. . This flask was immersed in an oil bath, the bath temperature was raised from room temperature to 70 ° C. over 1 hour, and polymerization was carried out at 70 ° C. for 8 hours.

  After completion of the polymerization, the polymerization solution was concentrated with an evaporator, and the polymer was precipitated in acetonitrile. Thereafter, the resulting polymer was vacuum-dried to obtain poly (acrylic acid-co-2-ethylhexyl acrylate). Next, 200.0 g of the poly (acrylic acid-co-2-ethylhexyl acrylate) was suspended in 600 mL of water, and then neutralized and dissolved with an aqueous sodium hydroxide solution to obtain an aqueous polymer solution. Random copolymer II was obtained by drying the resulting aqueous polymer solution.

The structure of the above polymer was confirmed by ¹ H-NMR using heavy water as a solvent. The composition ratio of the sodium acrylate unit and the 2-ethylhexyl acrylate unit in the random copolymer II determined by ¹ H-NMR was 42:58 (molar ratio). Moreover, the number average molecular weight (Mn) measured by GPC was 7000, and molecular weight distribution was 1.6.

[Production Example 7]: Preparation of microencapsulated black pigment dispersion (dispersion E) 9.4 g of styrene monomer, 0.10 g of crosslinker light ester TMP (Kyoeisha Chemical Co., Ltd.), initiator V-65 (Wako Pure) Yaku Kogyo Co., Ltd.) was mixed with 0.50 g to form a homogeneous solution, 4.4 g of this solution was added to 24.1 g of an aqueous solution (18.8 wt%) of random copolymer II obtained in Synthesis Example 3, and distilled water The solution was added dropwise to an aqueous solution diluted with 21.7 g and stirred with a stirrer for 10 minutes. This was treated with an ultrasonic disperser (“ULTRASONIC HOMOGENIZER UH-600” manufactured by SMT) for 10 minutes under ice cooling to prepare an emulsion.

  An aqueous solution diluted by adding 9.0 g of distilled water to 23.6 g of the aqueous solution (18.8 wt%) of the random copolymer II obtained in Synthesis Example 3 was added dropwise to the dispersion α80.0 g while stirring with a stirrer. Ultrasonic irradiation was performed for 5 minutes with an ultrasonic cleaner (“5510J-DTH” manufactured by BRANSONIC). Further, while stirring with a stirrer, 47.3 g of the previous emulsion was dropped, and the mixture was again treated with an ultrasonic cleaner for 30 minutes.

  The obtained dispersion was transferred to a four-necked flask having an internal volume of 200 mL equipped with a stirrer, a cooler, and a thermometer, and polymerized at 60 ° C. for 6 hours under a nitrogen stream while stirring at 250 rpm. After the polymerization is completed, the free random copolymer in the aqueous phase and excess ions are removed by ultrafiltration. After further concentration, the pH is adjusted to 8 with an aqueous sodium hydroxide solution, and the pigment concentration is 8% by weight. Liquid E was obtained.

[Production Example 8]: Preparation of microencapsulated black pigment dispersion (dispersion F) 9.4 g of trifluoroethyl methacrylate (light ester M-3F (Kyoeisha Chemical Co., Ltd.)), crosslinker light ester TMP (Kyoeisha Chemical Co., Ltd.) )) 0.10 g and initiator V-65 (Wako Pure Chemical Industries, Ltd.) 0.50 g were mixed to form a homogeneous solution, and 4.5 g of the solution was added to the random copolymer II aqueous solution obtained in Synthesis Example 3. (18.8% by weight) 24.1 g was added dropwise to an aqueous solution diluted with 21.7 g of distilled water, and stirred for 10 minutes. This was treated with an ultrasonic disperser (“ULTRASONIC HOMOGENIZER UH-600” manufactured by SMT) for 10 minutes under ice cooling to prepare an emulsion.
An aqueous solution diluted by adding 9.0 g of distilled water to 23.6 g of the aqueous solution (18.8 wt%) of the random copolymer II obtained in Synthesis Example 3 was added dropwise to the dispersion α80.0 g while stirring with a stirrer. Ultrasonic irradiation was performed for 5 minutes with an ultrasonic cleaner (“5510J-DTH” manufactured by BRANSONIC). Further, while stirring with a stirrer, 47.3 g of the previous emulsion was dropped, and the mixture was again treated with an ultrasonic cleaner for 30 minutes.
The obtained dispersion was transferred to a four-necked flask having an internal volume of 200 mL equipped with a stirrer, a cooler, and a thermometer, and polymerized at 60 ° C. for 6 hours under a nitrogen stream while stirring at 250 rpm. After the polymerization is completed, the free random copolymer in the aqueous phase and excess ions are removed by ultrafiltration. After further concentration, the pH is adjusted to 8 with an aqueous sodium hydroxide solution, and the pigment concentration is 8% by weight. Liquid F was obtained.

[Production Example 9]: Preparation of microencapsulated black pigment dispersion (dispersion G) Dispersion G in the same manner as in Production Example 8 except that octafluoropentyl acrylate was used instead of trifluoroethyl methacrylate as a monomer. Got.

[Example 1]
(Preparation of ink composition)
An ink composition was prepared according to the following formulation.
Dispersion A: 7.50 g
Distilled water: 3.82 g
Glycerin: 2.10 g
Triethylene glycol monobutyl ether: 0.15 g
1,2-hexanediol: 0.45 g
2-pyrrolidone: 0.38 g
Triethylene glycol: 0.30 g
Triisopanolamine: 0.15g
Olfine E1010 (Surfactant manufactured by Air Products): 0.15 g

  The above components were mixed, stirred for 15 minutes, subjected to ultrasonic dispersion treatment for 30 minutes, filtered through a membrane filter with a pore size of 8 μm (Millipore: made of nitrocellulose), and further filtered with a membrane filter with a pore size of 0.45 μm (ADVANTEC: made of cellulose acetate). Filtration was performed to obtain the ink composition of Example 1.

With respect to the obtained ink composition or dispersion A of Example 1, the following properties (a) to (h) were evaluated by the following test methods, and the results are shown in Table 1.
As a printer, an inkjet recording system printer (“EM-930C” manufactured by Seiko Epson Corporation) is used, and commercially available plain paper (“XEROX“ 4024 ”) and glossy paper (Seiko Epson glossy paper“ KA420PSK ”are used as printing paper. )).

(A) Average particle diameter of dispersed particles The average particle diameter was measured by diluting the ink composition 10,000 times with distilled water and attaching a diluted probe to Otsuka Electronics Co., Ltd. “FPAR-1000”. The value of the average particle diameter was calculated by the Cumulant method. Further, the same measurement was performed for the dispersion A.

(B) Viscosity The viscosity was measured using a rheometer (REOLOGICA AB Instruments; VAR-100; cone 1 ° / 55φ), and the value at a shear rate of 100 / sec was read.

(C) Stability The average particle diameter after holding the ink composition at 70 ° C. for 15 hours was measured by the same method as in the above (a). The smaller the increase in average particle size, the more stable.

(D) Polymer coating amount A solid content is measured using a moisture meter (Sartorius Co., Ltd .: MA45), and the residual ratio when the dispersion A is dried at 180 ° C. for 90 minutes is defined as a solid content value. : CB) and the weight ratio of the polymer (CB / polymer ratio).

(E) Ejection stability After filling the ink composition into a cartridge with a Seiko Epson EM-930C printer, 50 sheets were printed in plain paper mode, and visually observed for blurring, etc. It was evaluated with an indicator.
○: No fading △: Fading during printing ×: Image cannot be printed neatly

(F) Scratch resistance of recorded image On glossy paper (Seiko Epson Corp. “KA420PSK”) printed with an ink composition, the scratch resistance test was performed immediately after printing and after 1 hour according to the following indicators.
○: Color will not fade even when rubbed with fingers △: Color will fade slightly when rubbed with fingers ×: Peel off when rubbed with fingers

(G) Optical density (OD value) of recorded image
The optical density of a plain paper (“4024” manufactured by XEROX) printed with the ink composition was dried for 1 day at room temperature. The optical density measurement was performed using a Macbeth densitometer (Gretag-Macbeth AG: SpectroEye).

(H) Gloss of recorded image
The gloss of a glossy paper printed with an ink composition (“KA420PSK” manufactured by Seiko Epson Corporation) was dried at room temperature for 1 day, and the gloss was measured. Gloss measurement was performed using a Haze-Gloss meter (“Cat. No. 4601” manufactured by BYK Gardner), and the Gloss value was measured at 20 °.

[Examples 2 to 7]
Ink compositions of Examples 2 to 7 were obtained in the same manner as in Example 1 except that the dispersion A of Example 1 was changed to dispersions B to G, respectively. The characteristics (a) to (h) were evaluated in the same manner as in Example 1 for each dispersion and the obtained ink composition. The results are shown in Table 1.

[Production Example 10]: Preparation of random copolymer I black pigment dispersion (dispersion γ) 28.0 g of black pigment (Mitsubishi Chemical Corporation: carbon black # 960), aqueous solution of random copolymer I obtained in Synthesis Example 2 (13.6 wt% solid content) 205.9 g and 46.1 g of distilled water were mixed, and 0.5 mmφ zirconia beads were used as a medium and dispersed at 25 ° C. for 4 hours using a self-made bead mill. The pigment concentration was adjusted to 8% to obtain dispersion III.
Dispersion III was placed in a 500 mL tall beaker, the beaker was immersed in ice water, and dispersed for 60 minutes with an ultrasonic homogenizer (Nippon Seiki Seisakusho; US-600T; used chip 36 mmφ) to obtain Pigment Dispersion IV .
Distilled water was added to the dispersion IV to dilute it twice, and then the free polymer was removed by ultrafiltration, followed by concentration to obtain a dispersion γ having a pigment concentration of 8% by weight.

[Comparative Example 1]
An ink composition of Comparative Example 1 was produced in the same manner as in Example 1 except that the dispersion liquid A of Example 1 was changed to the above dispersion liquid γ. With respect to this ink composition, the characteristics (a) to (h) were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Production Example 11]: Preparation of random copolymer II black pigment dispersion (dispersion δ) 28.0 g of carbon black (Mitsubishi Chemical Corporation: # 960), aqueous solution of random copolymer II obtained in Synthesis Example 3 (solid) (18.8% by weight) 89.4 g and 162.6 g of distilled water were mixed, and 0.5 mmφ zirconia beads were used as a medium and dispersed at 25 ° C. for 4 hours using a self-made bead mill. Dispersion V was obtained by adjusting the concentration to 8%.
Dispersion V was placed in a 500 mL tall beaker, the beaker was immersed in ice water, and dispersed with an ultrasonic homogenizer (Nippon Seiki Seisakusho, US-600T; chip used 36 mmφ) for 60 minutes to obtain dispersion δ.

[Comparative Example 2]
An ink composition of Comparative Example 2 was produced in the same manner as in Example 1 except that the dispersion A of Example 1 was changed to the above dispersion δ. The properties (a) to (h) of the dispersion δ and this ink composition were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Production Example 12]: Preparation of microencapsulated black pigment dispersion (dispersion H) 14.1 g of styrene monomer, 0.15 g of crosslinker light ester TMP (Kyoeisha Chemical Co., Ltd.), initiator V-65 (Wako Pure) Yaku Kogyo Co., Ltd.) was mixed with 0.75 g to form a uniform solution, and 3.37 g of the solution was gradually added dropwise to the dispersion γ80.0 g obtained in Production Example 11 while stirring with a stirrer. Stirrer stirring was continued for a minute. This was irradiated with ultrasonic waves for 30 minutes with an ultrasonic cleaner (“5510J-DTH” manufactured by BRANSONIC), and then with an ultrasonic disperser (“ULTRASONIC HOMOGENIZER UH-600” manufactured by SMT) under ice cooling, 5 The mixture was treated for 1 minute, and further stirred for 1 hour with stirring. The mixture was transferred to a 200-mL four-necked flask equipped with a stirrer, a cooler, and a thermometer, and polymerized at 60 ° C. for 6 hours under a nitrogen stream while stirring at 250 rpm. After completion of the polymerization, the free anionic polymer in the aqueous phase is removed by ultrafiltration, and after further concentration, the pH is adjusted to 8 with an aqueous sodium hydroxide solution to obtain a dispersion H having a pigment concentration of 8% by weight. It was.

[Comparative Example 3]
An ink composition of Comparative Example 3 was produced in the same manner as in Example 1 except that the dispersion A in Example 1 was changed to the above-mentioned dispersion H. With respect to the dispersion H and the ink composition, the characteristics (a) to (h) were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Production Example 13]: Preparation of surfactant black pigment dispersion (dispersion ε) 28.0 g of black pigment (Mitsubishi Chemical Corporation: carbon black # 960), surfactant Neogen S-20 (Daiichi Kogyo Seiyaku) Ltd .; Active ingredient (sodium dodecylbenzenesulfonate 20% by weight) 140.0 g) and distilled water 112.0 g were mixed, and 0.5 mmφ zirconia beads were used as a medium for 4 hours at 25 ° C. using a self-made bead mill. After dispersing and removing the beads, dispersion VII was obtained by adjusting the pigment concentration to 8%.
Dispersion VII was placed in a 500 mL tall beaker, the beaker was immersed in ice water, and dispersed for 60 minutes with an ultrasonic homogenizer (Nippon Seiki Seisakusho; US-600T; used chip 36 mmφ) to obtain pigment dispersion VIII.
Distilled water was added to the obtained dispersion VIII to dilute it twice, and then the free surfactant was removed by ultrafiltration. After further concentration, the pH was adjusted to 8 with an aqueous sodium hydroxide solution, A dispersion ε having a pigment concentration of 8% by weight was obtained.

[Production Example 14]: Preparation of Microencapsulated Black Pigment Dispersion (Dispersion I) To dispersion ε37.5 g obtained in Production Example 13, 217.5 g of distilled water was added and diluted, and then 15 g of styrene monomer was obtained. Was added to a 1 L separable flask, and after substitution with nitrogen, the mixture was stirred at 200 rpm for 1 hour, slowly heated to an internal temperature of 70 ° C., and maintained at an internal temperature of 70 ° C., while maintaining potassium persulfate at room temperature. After stirring at 200 rpm for 1 hour, 10.0 g of an aqueous solution in which 0.3 g of KPS was dissolved as a polymerization initiator was added, and then 30.0 g of styrene monomer was slowly added dropwise over 6 hours, followed by further stirring for 2 hours. The polymerization was continued. After completion of the polymerization, the pH was adjusted to 8 with an aqueous sodium hydroxide solution, and then the polymer fine particles were removed by ultrafiltration, followed by concentration to obtain a dispersion I having a pigment concentration of 8% by weight.

[Comparative Example 4]
An ink composition of Comparative Example 4 was produced in the same manner as in Example 1 except that Dispersion A in Example 1 was changed to Dispersion I. About the dispersion liquid I and this ink composition, it carried out similarly to Example 1, and evaluated the characteristic of said (a)-(h). The results are shown in Table 1.

  From Table 1, the microencapsulated color material of the present invention has excellent dispersion stability, and the ink composition of the present invention using this microencapsulated color material has high ejection stability, high print density of recorded images, and abrasion resistance. It can be seen that it has excellent properties and color development.

Claims (4)

(1) A first step of adsorbing the polymer A having an ionic group on the surface of the colorant particle in an aqueous medium. (2) The polymer in the aqueous dispersion of the colorant particle having the polymer A adsorbed on the surface. Second step of adding and mixing polymer B having an ionic group having a charge opposite to that of ionic group of A (3) Hydrophilic monomer, hydrophobic monomer and polymerizability to the aqueous dispersion A method for producing a microencapsulated color material, comprising a third step of mixing and polymerizing one or more selected from the group consisting of surfactants and a polymerization initiator.   In the second step, the total number of dissociated ionic groups of the whole polymer B added to the aqueous dispersion is larger than the total number of dissociated ionic groups of the whole polymer A adsorbed on the surface of the colorant particles. The method for producing a microencapsulated color material according to claim 1.   The method for producing a microencapsulated color material according to claim 1 or 2, wherein in the second step, the polymer B contains a polymerizable group.   In the third step, one or more selected from the group consisting of a hydrophobic monomer and a polymerizable surfactant and a polymerization initiator are homogenized, and then added to the aqueous dispersion and emulsified. The method for producing a microencapsulated color material according to any one of claims 1 to 3, wherein: