JP2004249721A - Coating composition for inkjet recording body, and inkjet recording body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating composition for an inkjet recording body suitable for high speed printing, and to provide a coating composition, for an inkjet recording body, which can yield an ink receiving layer excellent in glossiness, light resistance, transparency, ink absorption, high resolution of ink images and the like. <P>SOLUTION: This coating composition for inkjet recording body comprises, as active ingredients, (A) an aqueous dispersion of a crosslinked polymer having an average particle diameter of 10 to 200 nm and a glass transition temperature of 50°C or above prepared by emulsion polymerization of an unsaturated monomer (M1) and a crosslinkable monomer (M2) in the presence of cationic and/or amphoteric emulsifiers, and (B) at least one hydrophilic resin selected from the group consisting of polyvinyl alcohol, polyvinyl pyrrolidone, and gelatin. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a coating composition for an ink jet recording medium containing an aqueous dispersion of specific crosslinked polymer fine particles and a specific hydrophilic resin as active ingredients, and an ink jet recording medium obtained by applying the coating composition. About. More specifically, it can be applied to an ink receiving layer of an ink jet recording medium suitable for high-speed printing, and is excellent in terms of gloss, light resistance, transparency, ink absorption, high resolution of an ink image, and the like of the receiving layer. The present invention relates to a body coating composition and an ink jet recording body having an ink receiving layer provided with an ink receiving layer containing the coating composition.

  The ink jet recording system has excellent characteristics such as low noise and high speed recording performance, and is therefore awarded in various fields such as information equipment. In the ink jet recording method, inorganic fine particles such as silica and alumina are used in the receiving layer in order to improve the ink absorbency.However, when a coating composition containing the inorganic fine particles is applied to a high quality paper, The ink receiving layer of the obtained ink jet recording medium has disadvantages such as poor glossiness, and when applied to a transparent support such as a synthetic resin film, the obtained ink receiving layer has poor glossiness and transparency. Further, there is a drawback that the inorganic fine particles fall off when the recording medium is bent or cut.

  For this reason, instead of the coating composition using the inorganic fine particles, a coating composition using polymer fine particles has been studied as the ink receiving layer of the ink jet recording medium. As a method thereof, for example, it has been proposed to use crosslinked polymer fine particles having an average particle diameter of 200 nm or less (see Patent Document 1), but such polymer fine particles are compared with those using inorganic fine particles. Although the transparency is excellent, when the coating composition is applied to the support and dried, since the polymer fine particles are melted and a sufficient void structure is not formed, the ink absorption is unsatisfactory and sharp. No image is obtained. Attempts have also been made to improve gloss by providing at least one hydrophilic binder layer with a hydrophilic binder layer having polymer latex particles having a weight of 2 to 8 times the weight of the hydrophilic binder as a lower layer. (See Patent Documents 2 and 3). However, this method has disadvantages such as a complicated manufacturing process of the ink jet recording medium and an increase in product cost. Further, an acrylic emulsion using glycidyltrimethylammonium chloride and / or polydimethylmethylenebiberidinium chloride has been proposed (see Patent Document 4). However, since the degree of crosslinking is low, the coating composition is coated on a support. When applying and drying, or when trying to impart gloss by treatment with a calender or the like, the heat resistance and pressure resistance are inferior, and fusion of polymer particles occurs, and a sufficient void structure is not formed. Absorption is unsatisfactory, and a clear image cannot be obtained.

JP-A-9-156211 JP-A-9-164759 JP-A-10-151852 JP-A-2002-160443

  In the present invention, it is possible to solve the problems in the prior art, that is, problems such as poor gloss, opacity, and detachment of inorganic fine particles at the time of bending and cutting of a recording medium, which are observed in an ink receiving layer using inorganic fine particles. It is an object of the present invention to solve problems such as poor ink absorptivity, poor resolution, and a complicated production process of an ink jet recording medium, which are observed in an ink receiving layer using the polymer fine particles. That is, an object of the present invention is to provide a coating composition for an ink jet recording medium suitable for high-speed printing, which can eliminate the disadvantages of inorganic fine particles and conventional polymer fine particles, and to provide the ink formed from the coating composition. To provide an ink jet recording material coating composition which is excellent in terms of gloss, light resistance, transparency, ink absorbency, high resolution of an ink image, etc. of a receiving layer, and simplify the manufacturing process of an ink jet recording material (hydrophilic It is an object of the present invention to provide an ink jet recording medium which does not need to be provided with a special resin layer and can further improve gloss by only calendering treatment) and can exhibit excellent various performances only with the ink receiving layer.

  The inventor of the present invention has conducted intensive studies focusing on a coating composition for forming an ink receiving layer in order to solve the above problems, and as a result, has found that a coating composition for an ink jet recording medium containing specific crosslinked polymer fine particles as an active ingredient. The present inventors have found that the above problems can be completely solved by using a composition, and have completed the present invention.

  That is, the present invention has an average particle diameter of 10 to 200 nm obtained by emulsion polymerization of an unsaturated monomer (M1) and a crosslinkable monomer (M2) in the presence of a cationic and / or amphoteric emulsifier, Contains, as active ingredients, an aqueous dispersion (A) of a crosslinked polymer having a glass transition temperature of 50 ° C. or higher and at least one hydrophilic resin (B) selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone and gelatin. A coating composition for an ink jet recording medium; and an ink jet recording body provided with an ink receiving layer containing the coating composition for an ink jet recording medium on a support.

  The coating composition for an ink jet recording medium of the present invention can be applied to an ink receiving layer of an ink jet recording medium suitable for high-speed printing. That is, it is possible to easily obtain an ink jet recording material having a receptor layer which is excellent in terms of gloss, light resistance, transparency, ink absorption, ink image resolution, and the like. Since the ink jet recording medium of the present invention has a receiving layer having excellent gloss, there is no need to provide a hydrophilic overcoat layer as seen in the prior art, and it has a great effect in terms of manufacturing process and product price. .

  The coating composition for an ink jet recording medium of the present invention and the ink jet recording medium provided with the ink receiving layer containing the coating composition will be described in detail below. The coating composition for an inkjet recording medium of the present invention comprises, as the essential components, an aqueous dispersion (A) (hereinafter, referred to as a component (A)) of specific crosslinked polymer fine particles described below and a specific hydrophilic resin (B). ) (Hereinafter referred to as component (B)).

  It is essential that the component (A) has an average particle diameter of 10 to 200 nm, and preferably 20 to 150 nm. In the present specification, the average particle diameter refers to an average value of the particle diameter in a water dispersion state measured by a light scattering method. When the average particle size is less than 10 nm, the voids formed in the ink receiving layer of the ink jet recording medium obtained when the ink is coated on the support are small, and the ink absorbency is poor. If it exceeds 200 nm, the glossiness of the ink receiving layer of the obtained ink jet recording medium is poor when coated on high quality paper, and the obtained ink receiving layer when coated on a transparent support such as a synthetic resin film. Gloss and transparency tend to deteriorate, and both are not preferred.

Since the glass transition temperature (hereinafter, referred to as Tg) of the crosslinked polymer fine particles in the component (A) is not clearly observed in actual measurement based on the crosslinked structure, the unsaturated monomer ( The Tg value of the polymer composed of M1) is conveniently referred to as the Tg of the crosslinked polymer fine particles in the component (A). That is,
_{1 / Tg = Σ (w i} / Tg i)
(Wherein, Tg: Copolymer Glass transition temperature (absolute temperature display), _{w i:} the weight fraction of each monomer component in the unsaturated monomer (M1) (i), Tg i: unsaturated monomer It is a glass transition temperature (expressed as absolute temperature) of a homopolymer of each monomer component (i) in the monomer (M1).

  The Tg of the component (A) must be 50 ° C. or higher, preferably 55 ° C. or higher. When the Tg is lower than 50 ° C., the crosslinked polymer fine particles are melted or deformed when the coating composition is applied to a support and dried even if the crosslinked monomer (M2) is crosslinked. Since no void structure is formed, the ink absorbency is unsatisfactory and a clear image cannot be obtained.

  As the emulsifier used in the production of the component (A), it is essential to use a cationic emulsifier and / or an amphoteric emulsifier, taking into account the stability of the coating liquid during preparation. In the case of a crosslinked polymer fine particle dispersion prepared using an anionic emulsifier, the interaction with an additive (cationic polymer solution) for the purpose of improving printing density and water resistance during preparation of a coating liquid. And the coating liquid is apt to cause aggregation, which is not preferable. Examples of the cationic emulsifier include primary amine salts, secondary amine salts, tertiary amine salts, imidazole salts, alkyl quaternary ammonium salts, alkyl benzene quaternary ammonium salts, sulfonium salts and phosphonium salts. Low molecular surfactants include cationic polymers containing a tertiary amino group or a quaternary ammonium group, including those having an unsaturated group in the molecular structure. Among the cationic emulsifiers exemplified above, alkyl quaternary ammonium salts are particularly preferred. Further, as a cationic reactive emulsifier, those having a polymerizable double bond in the molecular structure, for example, a repeating unit based on a nonionic unsaturated monomer, an unsaturated monomer having a tertiary amino group And a repeating unit based on a quaternized unsaturated monomer having a tertiary amino group (quaternary ammonium base) and a structural unit having a polymerizable double bond. Contained cationic emulsifier.

  Examples of the amphoteric emulsifier include amphoteric surfactants such as alanine-based, imidazonium betaine-based, amidopropyl betaine-based, and aminocarboxylates represented by aminodipropionate. Salts are preferred because they are readily available.

  In addition, besides the cationic emulsifier and the amphoteric emulsifier, various known anionic emulsifiers and nonionic emulsifiers may be used as long as the amount is small enough not to deteriorate the performance of the obtained ink jet recording material coating composition. .

  The unsaturated monomer (M1) used in the production of the component (A) is not particularly limited. For example, an alkyl (meth) acrylate (here, (meth) acrylate means the acrylate or methacrylate). The same applies hereinafter), hydroxyalkyl (meth) acrylate, polyethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, glycidyl (meth) acrylate and other (meth) acrylates; styrene, Styrenes such as α-methylstyrene and vinyltoluene; dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, N, N- An unsaturated monomer having a tertiary amino group such as ethylaminopropyl (meth) acrylamide or triallylamine; an unsaturated monomer having the tertiary amino group, and an inorganic acid such as hydrochloric acid, sulfuric acid or acetic acid. Salts of an unsaturated monomer having a tertiary amino group with an organic acid such as (meth) acrylic acid; salts of the tertiary amino group-containing unsaturated monomer, methyl chloride, benzyl chloride, Unsaturated monomer containing a quaternary ammonium salt obtained by reaction with a known quaternizing agent such as dimethyl sulfate, diethyl sulfate, epichlorohydrin, alkyl glycidyl ether, glycidyl methacrylate, sultone, substituted sulfonate, p-chloromethylstyrene. And body. The salts may be formed on the crosslinked polymer fine particles after producing the crosslinked polymer fine particles having a structural unit of an unsaturated monomer having a tertiary amino group. In addition, various known compounds such as vinyl esters such as vinyl acetate and (meth) acrylamide can be used. Any of the above unsaturated monomers can be used alone or in an appropriate combination of two or more.

  In the production of the component (A), the crosslinkable monomer (M2) is indispensably used in order to give the obtained crosslinked polymer fine particles a higher physical strength. Specific examples thereof include di (meth) acrylates such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, and triethylene glycol di (meth) acrylate, methylenebis (meth) acrylamide, and ethylenebis (meth) acrylamide. Bis (meth) acrylamide such as hexamethylenebis (meth) acrylamide, divinyl esters such as divinyl adipate and divinyl sebacate, allyl (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate, N-methylol ( (Meth) acrylamide, diallylamine, diallyldimethylammonium, diallylphthalate, diallylchlorendate, divinylbenzene, divinylbiphenyl, divinylnaphthalene Any bifunctional monomer; 1,3,5-tri (meth) acryloylhexahydro-s-triazine, triallyl isocyanurate, triallylamine, triallyl trimellitate, N, N-diallyl (meth) acrylamide, etc. Trifunctional monomer: tetramethylolethane tetra (meth) acrylate, tetraallyl pyromellitate, N, N, N ', N'-tetraallyl-1,4-diaminobutane, tetraallylamine salt, tetraallyloxyethane And the like. Among them, divinylbenzene is preferred from the viewpoint of reactivity, crosslinked structure, and availability. Any of these crosslinkable monomers can be used alone or in an appropriate mixture of two or more. The ratio of the unsaturated monomer (M1) to the crosslinkable monomer (M2) is usually 98 to 60% by weight of (M1) and 2 to 40% by weight of (M2) based on the total amount of the monomer. (M1) is 97 to 65% by weight, and (M2) is 3 to 35% by weight. When the amount of (M2) used is less than 2% by weight, when the ink jet recording medium is provided with an ink receiving layer containing the component (A) on a support, crosslinked fine particles of the component (A) are obtained. Intermediate fusion occurs and ink absorption tends to be poor. When the amount of (M2) used exceeds 40% by weight, agglomeration of produced particles occurs during polymerization, which tends to be larger than the target particle diameter.

  In the emulsion polymerization reaction for producing the component (A), the ratio between the total amount of the monomers (M1) and (M2) and the amount of the emulsifier used is determined by the average particle diameter of the component (A) obtained. Also, it must be carefully determined from the viewpoint of stability during emulsion polymerization. From the viewpoint of preventing the generation of aggregates, the amount of the emulsifier used (in terms of solid content) is about 0.5 to 20 parts by weight based on 100 parts by weight of the total of the monomers (M1) and (M2). Preferably, it is 0.7 to 18 parts by weight.

  In the emulsion polymerization, there are various conditions such as a polymerization temperature, a polymerization time, a polymerization initiator, a chain transfer agent, and a polymerization medium, but these conditions are not particularly limited, and may be appropriately selected from those in normal emulsion polymerization. May be selected and determined. For example, an emulsifier, water, an unsaturated monomer (M1) and a crosslinkable monomer (M2) are charged into a predetermined reaction vessel under an inert gas stream, emulsified, and a polymerization initiator is added thereto. The polymerization may be carried out by heating to a temperature of, for example, a chain transfer agent may be used if necessary. In addition, as a method for adding the monomer, any method such as batch addition, divided addition, and continuous dropping may be used. In producing the crosslinked polymer fine particles, the polymerization temperature and the polymerization time are not particularly limited, but are usually about 60 to 90 ° C. and about 1 to 8 hours. Examples of the polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, 2,2′-azobis (2-amidinopropane) dihydrochloride, and 2,2′-azobis [2-methylpropionamidine] dihydrochloride Water-soluble azo polymerization initiators such as salts, 2,2'-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} dihydrochloride, and water-soluble solutions such as hydrogen peroxide Redox-based polymerization initiators obtained by combining the above-mentioned persulfate and a reducing agent such as sodium hydrogen sulfite and sodium thiosulfate. The amount used is about 0.03 to 5 mol per 100 mol of the total amount of the monomers. In addition, at the time of emulsion polymerization, a light stabilizer such as a light stabilizer and an ultraviolet absorber, a fluorescent whitening agent, and the like may be added as necessary.

  The component (A) obtained as described above contains crosslinked polymer fine particles having an average particle diameter of 10 to 200 nm and a Tg of 50 ° C. or more in a solid content of 5 to 50% by weight, It is an aqueous dispersion having a pH of 3 to 8 and a viscosity at 25 ° C. of 1000 mPa · s or less.

  Various known water-soluble polymers are added to the coating composition for ink jet recording material from the viewpoint of coating suitability. In the coating composition for ink jet recording material of the present invention, the strength and support of the coating layer are improved. In order to further improve the adhesion to the body and the transparency, the component (B) which is a specific hydrophilic resin is an essential component in addition to the component (A). That is, the component (B), which is at least one selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone, and gelatin, has been selected from various known polymer resins through intensive studies. Among components (B), polyvinyl alcohol is particularly preferred from the viewpoint of price and storage stability. The amount of the component (B) used (in terms of solid content) is about 3 to 50 weight, preferably about 5 to 45 weight per 100 weight parts of the solid content of the component (A). When the value is below the lower limit, the crosslinked polymer fine particles tend to fall off the surface of the inkjet recording material product, and when the value exceeds the upper limit, the voids formed by the crosslinked polymer fine particles cause the hydrophilic resin (B ) Tends to be buried and ink absorptivity tends to decrease. Incidentally, within a range not departing from the object of the present invention, in order to further increase the water absorption of the ink in the ink receiving layer, silica, clay, talc, diatomaceous earth, calcium carbonate, blended various known fillers such as alumina. You may. Further, the coating composition for an inkjet recording medium of the present invention, if necessary, a viscosity modifier, a leveling agent, an antifoaming agent, a coloring agent, a stabilizer, an ultraviolet absorber, a reactive ultraviolet absorber, a sizing agent, Various additives such as a fixing agent and a retention aid can also be blended. The solid content concentration of the coating composition for an ink jet recording medium is usually about 1 to 70% by weight, preferably 5% by weight at the lower limit and 60% by weight at the upper limit. The viscosity of the composition is usually about 5 to 1000 mPa · s (25 ° C.).

By coating the coating composition for an ink jet recording medium of the present invention on various known supports, the ink jet recording medium of the present invention can be easily obtained. The support is not limited to paper or synthetic paper, and various types of synthetic resin films and supports provided with an ink receiving layer are also applicable. The method of applying the coating composition is not particularly limited, and a size press, a roll coater, an air doctor coater, an air knife coater, a blade coater, a curtain coater, a rod coater, a bar coater, and other types of coaters are used. can be applied to the support Te, coated amount of coated composition (in terms of solid content) is usually 1 to 30 g / ^{m 2} approximately, preferably 2~25g / ^{m 2.}

  Various conventionally known aqueous inks can be used for the ink jet recording medium of the present invention without any problem. The aqueous ink contains at least one of a water-soluble acid dye, a water-soluble direct dye, a water-soluble basic dye, a water-soluble reactive dye, a water-soluble dye such as a food colorant, and a water-dispersible pigment, If necessary, wetting agents, dye dissolving agents, preservatives, fungicides and the like are also added. The water-soluble acid dye includes C.I. I. Acid black, C.I. I. Acid blue, C.I. I. Acid Red, C.I. I. Acid Yellow and the like. Examples of the water-soluble direct dye include C.I. I. Acid Direct Black, C.I. I. Acid Direct Blue, C.I. I. Acid Direct Red, C.I. I. Acid Direct Yellow and the like. Examples of the water-dispersible pigment include pigment black, pigment blue, pigment red, pigment bio red, and pigment yellow. Water and various water-soluble organic solvents can be used as the solvent for the water-soluble ink.

  Hereinafter, the present invention will be described more specifically with reference to Synthesis Examples and Examples, but the present invention is not limited to such Synthesis Examples and Examples. In each example, all parts and percentages are by weight unless otherwise specified.

Synthesis Example 1
In a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen gas inlet tube and a thermometer, 732.5 parts of ion-exchanged water and sodium β-laurylaminodipropionate (a product of Cognis Japan, trade name) After charging 24.9 parts of "Deriphat 160C", active ingredient 30%), 196.2 parts of styrene, 24.2 parts of methyl methacrylate, divinylbenzene (trade name, manufactured by Nippon Steel Chemical Co., Ltd.) are stirred. 21.5 parts of “DVB-570” (purity: 57%) was added and emulsified. Then, 0.6 parts of 2,2'-azobis (2-amidinopropane) dihydrochloride was added, and the mixture was heated to 80 ° C. with stirring under a nitrogen atmosphere and kept at the temperature for 4 hours to complete the polymerization. An aqueous dispersion of crosslinked polymer fine particles having a particle diameter of 60 nm and a Tg of 101 ° C. was obtained.

Synthesis Example 2
After charging 720.9 parts of ion-exchanged water and 41.6 parts of the above-mentioned sodium β-laurylaminodipropionate into the same reaction vessel as in Synthesis Example 1, 150.9 parts of styrene and 23.7 parts of methyl methacrylate were stirred under stirring. And 62.4 parts of the above-mentioned divinylbenzene, and emulsified. Then, 0.6 parts of ammonium persulfate was added, and the mixture was heated to 80 ° C. with stirring under a nitrogen atmosphere and kept at that temperature for 4 hours to complete the polymerization, thereby obtaining a crosslinked polymer fine particle having an average particle diameter of 85 nm and a Tg of 101 ° C. An aqueous dispersion was obtained.

Synthesis Example 3
In a reaction vessel similar to that of Synthesis Example 1, 691.8 parts of ion-exchanged water and lauryltrimethylammonium chloride as a cationic surfactant (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., trade name “Katiogen TML”, active ingredient 30%) After charging 83.1 parts, 22.5 parts of styrene, 143.0 parts of methyl methacrylate, and 59.1 parts of the above-mentioned divinylbenzene were added to the mixture while stirring to emulsify. Then, 0.6 parts of 2,2'-azobis (2-amidinopropane) dihydrochloride was added, and the mixture was heated to 80 ° C. with stirring under a nitrogen atmosphere and kept at the temperature for 4 hours to complete the polymerization. An aqueous dispersion of crosslinked polymer fine particles having a particle diameter of 81 nm and a Tg of 104 ° C. was obtained.

Synthesis Example 4
After 666.6 parts of ion-exchanged water and 123.4 parts of lauryltrimethylammonium chloride were charged into the same reaction vessel as in Synthesis Example 1, 21.0 parts of styrene, 123.1 parts of methyl methacrylate, and butyl acrylate were stirred. 10.5 parts and 55.2 parts of the above-mentioned divinylbenzene were added and emulsified. Then, 0.6 parts of 2,2'-azobis (2-amidinopropane) dihydrochloride was added, and the mixture was heated to 80 ° C. with stirring under a nitrogen atmosphere and kept at the temperature for 4 hours to complete the polymerization. An aqueous dispersion of crosslinked polymer fine particles having a particle diameter of 90 nm and a Tg of 90 ° C. was obtained.

Synthesis Example 5
611.8 parts of ion-exchanged water and 204.0 parts of lauryltrimethylammonium chloride were charged into the same reaction vessel as in Synthesis Example 1, and then 18.4 parts of styrene, 66.3 parts of methyl methacrylate, and butyl acrylate were stirred. 18.5 parts and 80.5 parts of the above-mentioned divinylbenzene were added and emulsified. Then, 0.6 parts of 2,2'-azobis (2-amidinopropane) dihydrochloride was added, and the mixture was heated to 80 ° C. with stirring under a nitrogen atmosphere and kept at the temperature for 4 hours to complete the polymerization. An aqueous dispersion of crosslinked polymer fine particles having a particle diameter of 110 nm and a Tg of 77 ° C. was obtained.

Synthesis Example 6
After charging 737.7 parts of ion-exchanged water and 39.1 parts of lauryltrimethylammonium chloride in the same reaction vessel as in Synthesis Example 1, 40.1 parts of styrene, 63.9 parts of methyl methacrylate, and butyl acrylate were stirred. 60.1 parts and 58.6 parts of the above-mentioned divinylbenzene were added and emulsified. Then, 0.6 parts of 2,2'-azobis (2-amidinopropane) dihydrochloride was added, and the mixture was heated to 80 ° C. with stirring under a nitrogen atmosphere and kept at the temperature for 4 hours to complete the polymerization. An aqueous dispersion of crosslinked polymer fine particles having a particle diameter of 85 nm and a Tg of 40 ° C. was obtained.

Synthesis Example 7
717.1 parts of ion-exchanged water and 42.3 parts of cetyltrimethylammonium chloride (trade name “Katiogen TMP” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) were charged into the same reaction vessel as in Synthesis Example 1, and then stirred. Below, 90.9 parts of styrene, 89.7 parts of methyl methacrylate, 14.6 parts of methyl chloride salt of dimethylaminoethyl methacrylate (trade name “Acryester DMC”, manufactured by Mitsubishi Rayon Co., purity: 80%), the divinyl The mixture was emulsified by adding 40.8 parts of benzene, and 1.6 parts of 2,2'-azobis (2-amidinopropane) dihydrochloride was added thereto. The temperature was maintained for a period of time to complete the polymerization, and an aqueous dispersion of crosslinked polymer fine particles having an average particle diameter of 90 nm and a Tg of 98 ° C. was obtained.

Synthesis Example 8
696.6 parts of ion-exchanged water and 42.3 parts of cetyltrimethylammonium chloride were charged into the same reaction vessel as in Synthesis Example 1, and then 90.9 parts of styrene, 78.1 parts of methyl methacrylate, and acrylamide ( 46.6 parts of “Acrylamide” (trade name, manufactured by Diatrinix Co., Ltd., purity: 50%) and 40.8 parts of the above-mentioned divinylbenzene were added and emulsified. Then, 1.8 parts of 2,2′-azobis (2-amidinopropane) dihydrochloride was added, and the mixture was heated to 80 ° C. with stirring under a nitrogen atmosphere and kept at that temperature for 4 hours to complete the polymerization. An aqueous dispersion of crosslinked polymer fine particles having a particle diameter of 95 nm and a Tg of 107 ° C. was obtained.

Synthesis Example 9
733.8 parts of ion-exchanged water and 42.3 parts of the above cetyltrimethylammonium chloride were charged into the same reaction vessel as in Synthesis Example 1, and then, with stirring, 79.3 parts of styrene, 78.1 parts of methyl methacrylate, and dimethylamino 14.6 parts of methyl chloride salt of ethyl methacrylate, 46.6 parts of acrylamide and 40.8 parts of the above-mentioned divinylbenzene were added and emulsified. Then, 1.7 parts of 2,2′-azobis (2-amidinopropane) dihydrochloride was added, and the mixture was heated to 80 ° C. with stirring under a nitrogen atmosphere and kept at the temperature for 4 hours to complete the polymerization. An aqueous dispersion of crosslinked polymer fine particles having a particle diameter of 105 nm and a Tg of 103 ° C. was obtained.

表中、乳化剤（ａ）とは、β−ラウリルアミノジプロピオン酸ナトリウム（コグニスジャパン社製、商品名「デリファット１６０Ｃ」）を、乳化剤（ｂ）とは、ラウリルトリメチルアンモニウムクロライド（第一工業製薬（株）製、商品名「カチオーゲンＴＭＬ」）を、乳化剤（ｃ）とは、セチルトリメチルアンモニウムクロライド（第一工業製薬（株）製、商品名「カチオーゲンＴＭＰ」）をいう。乳化剤使用量（固形分換算）とは、乳化剤固形分、不飽和単量体（Ｍ１）および架橋性単量体（Ｍ２）の合計量に対する乳化剤固形分使用量の百分率をいう。ジビニルベンゼン使用量とは、当該単量体の合計量に対するジビニルベンゼン使用量の百分率をいう。

In the table, the emulsifier (a) is sodium β-laurylaminodipropionate (trade name “Deriphat 160C” manufactured by Cognis Japan), and the emulsifier (b) is lauryltrimethylammonium chloride (Daiichi Kogyo Seiyaku) The emulsifier (c) refers to cetyltrimethylammonium chloride (trade name "Katiogen TMP", manufactured by Daiichi Kogyo Seiyaku Co., Ltd.). The used amount of the emulsifier (in terms of solid content) refers to the percentage of the used amount of the emulsifier solid content to the total amount of the emulsifier solid content, the unsaturated monomer (M1) and the crosslinkable monomer (M2). The amount of divinylbenzene used refers to the percentage of the amount of divinylbenzene used relative to the total amount of the monomer.

Example 1 (Preparation of Coating Composition for Inkjet Recording Body and Inkjet Recording Body)
40 parts (solid content: 10 parts) of an aqueous dispersion of the crosslinked polymer fine particles obtained in Synthesis Example 1 and 10 parts of polyvinyl alcohol (manufactured by Kuraray Co., Ltd., trade name “PVA-117”, average degree of polymerization: 1700 to 2400) % Aqueous solution and 5.0 parts of ion-exchanged water were uniformly mixed to prepare a coating composition having a solid content of 20%. Next, the coating composition was applied to one side of a support (commercially available high-quality paper (basis weight: 80 g / m ² ) and a transparent OHP film) using a bar coater so as to have a solid content of 10 g / m ^2. And dried at 100 ° C. for 10 minutes to obtain an ink jet recording material.

Examples 2 to 8
In the same manner as in Example 1, except that an aqueous dispersion of various crosslinked polymer fine particles shown in Table 1 was used instead of the aqueous dispersion of crosslinked polymer fine particles (the one in Synthesis Example 1), the solid content was 20%. Was prepared. Similarly, an ink jet recording medium was obtained.

Comparative Example 1
40 parts of an aqueous dispersion of the crosslinked polymer fine particles obtained in Synthesis Example 6 (solid content: 10 parts), 10 parts of a 10% aqueous solution of polyvinyl alcohol (same as above), and 5.0 parts of ion-exchanged water are uniformly mixed. A coating composition having a solid content of 20% was prepared. Then, the coating composition was applied to one side of the support and dried in the same manner as in Example 1 to obtain an ink jet recording medium.

Comparative Example 2
In Example 1, 100 parts of an aqueous dispersion of colloidal silica (trade name "Snowtex O", manufactured by Nissan Chemical Industries, Ltd.) was used in place of the aqueous dispersion of the crosslinked polymer fine particles obtained in Synthesis Example 1. Other than that obtained the inkjet recording body similarly.

(Performance of inkjet recording medium)
The performance evaluation of the ink jet recording materials obtained in Examples 1 to 8 and Comparative Examples 1 and 2 was performed using an ink jet printer (manufactured by Canon Inc., trade name “BJF-9000”) using black, yellow, cyan, Each color of magenta was printed in a grid pattern of a 10 mm image (setting conditions for glossy film), and the measurement was performed based on the following measurement method. The results are shown in Table 2.

(1) Ink Absorbability A state in which the image immediately after printing is touched by the finger and no ink adheres and the adjacent image is not bleeding is indicated by “O”, and ink partially adheres to the fingertip slightly or is adjacent to the fingertip. The state in which the images slightly permeated each other was indicated by Δ, and the state in which some of the ink adhered to the fingertips or in which the adjacent images permeated each other was indicated by x.
(2) Gloss Using a variable-angle gloss meter (trade name “VG-1001DP” manufactured by Nippon Denshoku Industries Co., Ltd.), the surface gloss (75 °) of the unprinted white portion was measured.
(3) Print density After printing each color of black, yellow, cyan, and magenta, it was measured by SpectroEye (Gretag Macbeth).
(4) Transparency haze meter (trade name “NDH-2000” manufactured by Nippon Denshoku Industries Co., Ltd.) was used to measure the parallel light transmittance.
(5) The powder-removing surface was rubbed with a toe, and the state where the ink-receiving layer was easily peeled off was evaluated as x, and the state where the ink-receiving layer was not peeled off even when strongly rubbed was evaluated as ○.
(6) Heat resistance After the ink jet recording medium provided with the ink receiving layer is heated at 100 ° C. for 10 minutes and further at 150 ° C. for 15 minutes using a normal air dryer, the surface of the ink jet recording medium is subjected to an electron microscope (manufactured by Hitachi, Ltd.). It was observed at a magnification of 100,000 using a trade name “S-800”). The state where the shape of the polymer fine particles was lost was evaluated as X, the state where the shape was confirmed but partially fused was evaluated as △, and the state where the shape was maintained was evaluated as ○.

表中、（Ａ）／（Ｂ）とは、（Ａ）成分と（Ｂ）成分の各固形分比率を示す。

In the table, (A) / (B) indicates the respective solid content ratios of the component (A) and the component (B).

Claims (6)

Emulsion polymerization of an unsaturated monomer (M1) and a crosslinkable monomer (M2) in the presence of a cationic and / or amphoteric emulsifier has an average particle size of 10 to 200 nm and a glass transition temperature of 50 ° C. The aqueous dispersion of the crosslinked polymer (A) described above and at least one hydrophilic resin (B) selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone and gelatin are contained as active ingredients. Coating composition for ink jet recording medium. The coating composition for an ink jet recording material according to claim 1, wherein the cationic emulsifier is an aliphatic quaternary ammonium salt. The coating composition for an ink jet recording material according to claim 1, wherein the amphoteric emulsifier is an aminocarboxylate. The coating composition for an ink jet recording material according to any one of claims 1 to 3, wherein the crosslinkable monomer (M2) is divinylbenzene. The coating composition for an ink jet recording medium according to any one of claims 1 to 4, wherein the proportion of (A) and (B) used is 100 parts by weight: (3 to 50) parts by weight in terms of solid content. An ink jet recording material provided with an ink receiving layer comprising the coating composition for an ink jet recording material according to claim 1 on a support.