JP4509939B2 - Resin composition for ink recording medium and ink recording medium - Google Patents

Description

  The present invention relates to a resin composition for an ink recording material and an ink recording material. More specifically, it is formed by using a resin composition for an ink recording medium that has not only excellent ink absorption and water resistance but also improved scratch resistance on the surface of the image receiving layer, and the resin composition for an ink recording medium. The present invention relates to an ink recording body having an image receiving layer.

  Inkjet recording systems are rapidly becoming popular in recent years because they are inexpensive, easy to achieve full color, low noise, and excellent print quality. For inkjet recording, water-based dye ink is mainly used from the viewpoint of safety and recording suitability, and recording is performed by ejecting ink dots from a nozzle toward a recording sheet. For this reason, the recording sheet is required to absorb ink promptly. Furthermore, with the increase in the number of ink colors and the smaller ink dot particle size, it has become possible to obtain recordings that are comparable to silver salt photographic images, and the recording speed has been increased. As described above, the recording apparatus and the recording method have been improved, and in response to this, advanced characteristics have been required for the ink jet recording material.

  Various recording papers are used as ink jet recording materials. For example, ink is applied to various supports such as plain paper, coated paper (art paper, coated paper, cast coated paper, etc.), transparent or opaque plastic film, and synthetic paper or RC paper coated on both sides of paper. Recording paper provided with a receiving recording layer is used.

  The ink receiving layer can be roughly divided into a swelling type ink receiving layer mainly composed of a hydrophilic resin and a void type ink receiving layer mainly composed of a fine particle component. However, as the recording speed increases. A void-type ink receiving layer having excellent ink absorbability has become mainstream.

  The void-type ink-receiving layer exhibits high ink absorbability because it absorbs ink in the void, hardly causes image defects such as beading, and has high water resistance since it is mainly composed of water-insoluble inorganic fine particles. In addition, the surface of the ink receiving layer set to a thickness that can secure a sufficient ink absorption capacity is apparently dried immediately after printing, and a drying speed that allows touching and overlapping is obtained.

  With respect to the void type ink receiving layer, conventionally, in order to reduce the particle size of the inorganic fine particles contained in order to increase the glossiness of the ink receiving layer or to prevent the ink absorption from being lowered due to the gap being blocked, the binder resin is used. Studies such as reducing the content have been made (for example, see Patent Documents 1 to 6). However, since the coating film forming the ink receiving layer becomes brittle and inorganic fine particles fall off and cracks and high flatness cannot be obtained, high glossiness and a clear printed image cannot be obtained. Due to the low mechanical stability, there were problems such as precipitation and separation of inorganic fine particle components contained during production.

  Furthermore, as described above, in recent years, an image comparable to a silver salt photograph has been obtained, and accordingly, the influence on the printed image due to the scratches on the surface of the ink jet recording layer has become remarkable. Inkjet recordings are often stacked when stored or set in a printer, and the surface layer is very likely to be damaged by rubbing the backside and surface layer of the recording unit. Improving the scratch resistance of the layer has become a major challenge.

Japanese Unexamined Patent Publication No. 60-219084 JP 63-170074 A JP-A-2-43083 JP-A-4-93284 JP-A-7-137431 JP-A-8-197832

  The object of the present invention is to prevent inorganic fine particles from falling off or cracking, to obtain a high gloss and clear printed image, to improve the scratching of the surface, and to have high mechanical stability and the inorganic fine particle components are settled. An object of the present invention is to provide an ink recording material having a resin composition for an ink recording material that is difficult to separate and an image receiving layer formed of the composition.

  As a result of intensive studies to achieve the above object, the present inventors have found that a resin composition comprising a crosslinkable group-containing acrylic copolymer obtained by copolymerizing a monomer having a specific structure and inorganic fine particles, and a specific structure The resin composition comprising a monomer having a specific structure, a compound having a specific structure and inorganic fine particles has high mechanical stability in the form of a dispersion, and the inorganic fine particle components are difficult to settle and separate. In the case of forming, the present inventors have found that the inorganic fine particles are not dropped off or cracked, a high gloss and a clear printed image can be obtained, and the scratch resistance is excellent.

That is, the present invention is the ink record-body resin composition comprising an acrylic copolymer obtained by copolymerizing a monomer having a structure represented by the following formula (a1) and (A1) inorganic fine particles and (B) There,
The ratio of the monomer having the structure represented by the formula (a1) to the total monomer amount of the acrylic copolymer (A1) is 0.5 to 30% by weight,
The ratio of the nonionic monomer to the total monomer amount of the acrylic copolymer (A1) is 40 to 95% by weight,
The ratio of the cationic monomer to the total monomer amount of the acrylic copolymer (A1) is 1 to 30% by weight.
A resin composition for an ink recording medium is provided.

The present invention also includes an acrylic copolymer (A1) obtained by copolymerizing a monomer having a structure represented by the following formula (a1) and at least two structures represented by the following formula (a2). A resin composition for an ink recording medium comprising a compound (A2) and inorganic fine particles (B) ,
The ratio of the monomer having the structure represented by the formula (a1) to the total monomer amount of the acrylic copolymer (A1) is 0.5 to 30% by weight,
The ratio of the nonionic monomer to the total monomer amount of the acrylic copolymer (A1) is 40 to 95% by weight,
The ratio of the cationic monomer to the total monomer amount of the acrylic copolymer (A1) is 1 to 30% by weight.
A resin composition for an ink recording medium is provided.

  As the inorganic fine particles (B), for example, at least one selected from the group consisting of dry silica, wet silica, sol-gel silica, colloidal silica, and alumina sol can be used.

The present invention further provides an ink recording medium having at least one image-receiving layer formed from the above-mentioned resin composition for an ink recording medium on at least one surface of a substrate.
In this specification, in addition to the above-described invention, an ink recording comprising an acrylic copolymer (A1) copolymerized with a monomer having a structure represented by the following formula (a1) and inorganic fine particles (B) An acrylic copolymer (A1) obtained by copolymerizing a resin composition for body and a monomer having a structure represented by the following formula (a1) and at least two structures represented by the following formula (a2) A resin composition for an ink recording medium comprising the compound (A2) contained and the inorganic fine particles (B) will also be described.

  According to the resin composition for an ink recording material of the present invention, the mechanical stability is high and the inorganic fine particle component is difficult to settle and separate. Further, an ink recording material having an image receiving layer formed from this resin composition has extremely high scratch resistance on the surface. In addition, the image-receiving layer is less likely to cause the removal or cracking of inorganic fine particles, has high gloss, and can obtain a clear printed image by ink jet recording.

  The resin composition for an ink recording material of the present invention comprises an acrylic copolymer (A1) copolymerized with a monomer having a structure represented by the formula (a1) and inorganic fine particles (B), or the formula ( Acrylic copolymer (A1) copolymerized with a monomer having the structure represented by a1), compound (A2) containing at least two structures represented by the formula (a2), and inorganic fine particles (B ) And.

[Acrylic copolymer (A1) copolymerized with a monomer having the structure represented by formula (a1)]
The acrylic copolymer (A1) obtained by copolymerizing the monomer having the structure represented by the formula (a1) (hereinafter sometimes simply referred to as “acrylic copolymer (A1)”) has the formula ( It is not particularly limited as long as it is an acrylic copolymer having at least a structural unit (repeating unit) derived from a monomer having the structure represented by a1).

  As a monomer having a structure represented by the formula (a1), a polymerizable unsaturated bond such as a vinyl group, an allyl group, an acryloyl group, or a methacryloyl group is included in the molecule together with the group represented by the formula (a1). A variety of compounds having containing groups can be used. Representative examples of the monomer having the structure represented by the formula (a1) include diacetone acrylamide and diacetone methacrylamide. Monomers having a structure represented by the formula (a1) can be used alone or in combination of two or more.

  By using an acrylic copolymer obtained by copolymerizing such a monomer, the hardness of the surface of the ink recording material is improved, and the scratch resistance of the surface of the recording material is remarkably improved.

  The acrylic copolymer (A1) obtained by copolymerizing the monomer having the structure represented by the formula (a1) can be imparted with a cationic property or an anionic property as necessary.

  The method of imparting cationicity to the acrylic copolymer (A1) (method of introducing a cationic group) is not particularly limited. For example, (1) a tertiary amino group (disubstituted amino group) A method in which a monomer having a tertiary amino group is neutralized with an acid to form a salt, and (2) a monomer having a tertiary amino group is neutralized with an acid. (After making into a salt), a method for subjecting to copolymerization, (3) a method for subjecting a monomer having a quaternary ammonium base to copolymerization, (4) a monomer having a group capable of forming a quaternary ammonium base Any method such as a method of subjecting the product to quaternary ammonium conversion after copolymerization may be employed. Two or more of these methods may be combined. Examples of the group capable of forming a quaternary ammonium base include a tertiary amino group. A quaternary ammonium can be formed by reacting the tertiary amino group with an alkylating agent (for example, epichlorohydrin, methyl chloride, benzyl chloride, etc.).

Typical examples of the monomer used for imparting cationicity (hereinafter sometimes referred to as “cationic monomer”) include, for example, N- (dimethylaminoethyl) (meth) acrylamide, N- N-dialkylamino-alkyl (meth) acrylamides such as (diethylaminoethyl) (meth) acrylamide, N- (dimethylaminopropyl) (meth) acrylamide, N- (diethylaminopropyl) (meth) acrylamide or salts thereof [e.g. N- (diC _1-4 alkylamino-C _2-3 alkyl) (meth) acrylamide] or a salt thereof; dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylamino Propyl (meth) acrylate or salt thereof Dialkylamino - alkyl (meth) acrylates [for example, di-C _1-4 alkylamino -C _2-3 alkyl (meth) acrylate] or a salt thereof; 4- (2-dimethylaminoethyl) styrene, 4- (2- Didimethylaminopropyl) styrene or a di-C _1-4 alkylamino-C _2-4 alkyl group-substituted aromatic vinyl compound or salt thereof such as a salt; nitrogen atom such as vinylpyridine, vinylimidazole, vinylpyrrolidone or a salt thereof Containing heterocyclic monomers or salts thereof; (meth) acryloyloxyalkyltrialkylammonium halides such as (meth) acryloyloxyethyltrimethylammonium chloride [for example, (meth) acryloyloxy C _2-4 alkyl-tri C _{1- 4} alkylammonium halides such as] an onium salt group-containing polymerizable unsaturated such as And monomers. These cationic monomers can be used alone or in combination of two or more. Examples of the salt include hydrogen halide salts (hydrochloride, hydrobromide, etc.), sulfate, alkyl sulfate (methyl sulfate, ethyl sulfate, etc.), alkyl sulfonate, aryl sulfonate, carvone Examples thereof include acid salts (formate, acetate, propionate, etc.).

  The method of imparting anionicity to the acrylic copolymer (A1) (method of introducing an anionic group) is not particularly limited, but for example, a monomer containing an acid group such as a carboxyl group or a sulfonic acid group Examples thereof include a method in which a body is subjected to copolymerization, and then neutralized with a base to obtain a salt, and a method in which the acid group-containing monomer is neutralized with a base to obtain a salt and then subjected to copolymerization.

  As typical examples of monomers used for anionic property (hereinafter sometimes referred to as “anionic monomers”), for example, carboxyethyl (meth) acrylate, carboxypropyl (meth) acrylate, Vinyl carboxylic acid [(meth) acrylic acid, crotonic acid, sorbic acid, maleic acid, itaconic acid, cinnamic acid, etc.], vinyl sulfonic acid [vinyl sulfonic acid, allyl sulfonic acid, vinyl toluene sulfonic acid, styrene sulfonic acid, etc.] , (Meth) acrylic sulfonic acid [(meth) acrylic sulfoethyl, sulfopropyl (meth) acrylic acid, etc.], (meth) acrylamide sulfonic acid [such as 2-acrylamido-2-methyl-propanesulfonic acid], or salts thereof Etc. An anionic monomer can be used individually or in combination of 2 or more types. Examples of the salt include ammonium salts, alkali metal salts, alkaline earth metal salts, salts with amines, and the like.

For the preparation of the acrylic copolymer (A1), other monomers are usually used in combination in order to further adjust the film formability and film properties. Such other monomers can be divided into hydrophilic monomers and nonionic monomers. Examples of hydrophilic monomers include, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate Hydroxyl group-containing monomers such as (meth) acrylic acid hydroxy C _2-6 alkyl ester such as: (meth) acrylamide, α-ethyl (meth) acrylamide, N-methyl (meth) acrylamide, N-butoxymethyl Amide group-containing monomers such as (meth) acrylamide; ether group-containing monomers to which vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether belong; diethylene glycol mono (meth) acrylate, triethylene glycol mono (meta ) Acrylate, polyethylene grease Rumono (meth) polyoxyalkylene group-containing monomer such as acrylate can be exemplified. A hydrophilic monomer can be used individually or in combination of 2 or more types.

Nonionic monomers include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, ( Isobutyl acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, (meth) acrylic acid (Meth) acrylic acid C _1-18 alkyl ester such as stearyl; (meth) acrylic acid cycloalkyl ester such as (meth) acrylic acid cyclohexyl; (meth) acrylic acid aryl ester such as phenyl (meth) acrylate; (Meth) acrylic acid aralkyl esters such as benzyl methacrylate; styrene, vinyl tolu And aromatic vinyl compounds such as α-methylstyrene; vinyl esters such as vinyl acetate, vinyl propionate and vinyl versatate; allyl esters such as allyl acetate; halogen-containing monomers such as vinylidene chloride and vinyl chloride; And vinyl cyanides such as (meth) acrylonitrile; olefins such as ethylene and propylene. As the nonionic monomer, (meth) acrylic acid C _1-18 alkyl ester [especially acrylic acid C _2-10 alkyl ester, methacrylic acid C _1-6 alkyl ester], aromatic vinyl compounds ( For example, styrene) and vinyl esters (for example, vinyl acetate) are used. A nonionic monomer can be used individually or in combination of 2 or more types.

  When the acrylic copolymer (A1) is synthesized by combining the above monomers, the proportion of each monomer used is not particularly limited. For example, the formula (a1) with respect to the total amount of monomers The ratio of the monomer having a structure represented by the formula is 0.1 to 50% by weight (preferably 0.5 to 30% by weight, more preferably 1 to 20% by weight, particularly 5 to 20% by weight). . The ratio of the nonionic monomer to the total amount of monomers is, for example, about 30 to 99% by weight, preferably about 40 to 95% by weight, more preferably about 50 to 93% by weight (particularly about 60 to 83% by weight). is there. Furthermore, the ratio of the cationic monomer or the anionic monomer to the total monomer amount is, for example, 0 to 50% by weight, preferably 1 to 30% by weight, more preferably 2 to 20% by weight (particularly 3 to 15%). % By weight).

The weight-average molecular weight of the acrylic copolymer (A1) is not particularly limited, for example, 1.0 × 10 ³ ~1.0 × 10 ^7, preferably about 5.0 × 10 ³ ~5.0 × 10 approximately ⁵ It is.

  As a polymerization method for obtaining the acrylic copolymer (A1), known polymerization methods such as emulsion polymerization can be used, but after solution polymerization of each of the above copolymerization components in a suitable organic solvent, Water is added to the resulting resin solution to emulsify, and the solvent used in the solution polymerization is removed to obtain an aqueous resin composition, or after removing the organic solvent from the resin solution, water is added to the aqueous resin composition. The method of obtaining the composition is preferably used. The polymerization operation may be a batch type or a continuous type.

  Examples of the organic solvent used for the solution polymerization include alcohols (eg, ethanol, isopropyl alcohol, n-butanol, etc.), aromatic hydrocarbons (eg, benzene, toluene, xylene, etc.), aliphatic hydrocarbons (eg, pentane, Hexane, heptane, etc.), alicyclic hydrocarbons (eg, cyclohexane, etc.), esters (eg, ethyl acetate, n-butyl acetate, etc.), ketones (eg, acetone, methyl ethyl ketone, etc.), ethers (eg, diethyl ether, Dioxane, tetrahydrofuran, etc.) can be used. These organic solvents may be used alone or in combination of two or more. As the organic solvent, alcohols such as isopropanol, aromatic hydrocarbons such as toluene, and ketones such as methyl ethyl ketone are usually used.

  The amount of the organic solvent used is not particularly limited. For example, the weight ratio of the amount of the organic solvent to the total amount of the polymerizable unsaturated monomers is usually 0.1 / 1 to 5/1, preferably 0.5 / The range can be selected from 1 to 2/1.

  In solution polymerization, polymerization may be started by irradiation heating with an electron beam or ultraviolet rays, but the polymerization is often started using a polymerization initiator. Examples of the polymerization initiator include azo compounds [for example, azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile, azobiscyanovaleric acid, 2,2′-azobis (2-amidinopropane] ) Hydrochloride, 2,2′-azobis (2-amidinopropane) acetate, etc.], inorganic peroxides (eg, persulfates such as potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide), organic peroxides Oxides [eg, benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, bis (2-ethoxyethyl) peroxydicarbonate], and redox catalysts [eg, sulfites or bisulfites (eg, , Alkali metal salts, ammonium salts, etc.), reduction of L-ascorbic acid, erythorbic acid, etc. And a persulfate (for example, alkali metal salt, ammonium salt, etc.), a catalyst system comprising a combination with an oxidizing agent such as a peroxide] etc. The polymerization initiator may be used alone or in combination of two or more. Can be used.

  The amount of the polymerization initiator used is not particularly limited, and is, for example, 0.001 to 20% by weight, preferably 0.01 to 10% by weight, particularly preferably 0, based on the total weight of the polymerizable unsaturated monomer. .1 to 10% by weight can be selected.

Although the reaction temperature in solution polymerization is not specifically limited, For example, it is 50-150 degreeC, Preferably, it is 70-130 degreeC. The reaction time is not particularly limited, and is, for example, 1 to 10 hours, preferably 2 to 8 hours. The end point of the polymerization can be confirmed by the disappearance of the double bond absorption (1648 cm ⁻¹ ) in the infrared absorption spectrum or the decrease of the unreacted monomer using gas chromatography.

  In solution polymerization, in order to adjust the molecular weight of the polymer, a chain transfer agent, for example, alcohol such as catechol or phenols, mercaptans (for example, n-lauryl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan). , 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane) and the like.

  Emulsification of the copolymer obtained by solution polymerization can be carried out in the presence or absence of an organic solvent. When the copolymer is emulsified in water in the presence of an organic solvent, for example, an additive (eg, an emulsifier, a pH adjuster, an acid, etc.) is added to the organic solution containing the copolymer, and then water is added. Emulsify. In this case, water is preferably added gradually by dropping or the like. The emulsification temperature is preferably lower, and can be selected from the range of, for example, 5 to 70 ° C, preferably 10 to 50 ° C. As the organic solvent, a water-soluble organic solvent (for example, alcohol such as isopropanol) is often used.

  When the copolymer is emulsified in water in the presence of an organic solvent, the organic solvent is removed by evaporation or the like after emulsification. The removal of the organic solvent is often performed, for example, at a temperature of 5 to 80 ° C. under normal pressure or reduced pressure [for example, 0.0001 to 1 atmosphere (0.00001 to 0.1 MPa)]. In addition, when removing an organic solvent before emulsifying a copolymer, a low boiling point organic solvent (for example, ketones, such as methyl ethyl ketone) is used in many cases.

  When the acrylic copolymer (A1) is obtained by emulsion polymerization, a general method for carrying out emulsion polymerization can be employed.

[Compound (A2) containing at least two structures represented by formula (a2)]
Polyhydrazide compounds such as various dihydrazide compounds are used as the compound (A2) containing at least two structures represented by the formula (a2) (hereinafter sometimes simply referred to as “compound (A2)”) it can. Specific examples of the compound (A2) include, for example, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, suberic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, Aliphatic polyhydrazide compounds such as saturated or unsaturated aliphatic dicarboxylic acid dihydrazides (for example, aliphatic dicarboxylic acid dihydrazides having about 2 to 14 carbon atoms) such as acid dihydrazide and citraconic acid dihydrazide; cyclohexane-1,4-biscarbohydrate Cycloaliphatic polyhydrazide compounds such as alicyclic dicarboxylic acid dihydrazide such as hydrazide and cyclohexane-1,2-biscarbohydrazide; phthalic dihydrazide, isophthalic dihydrazide, terephthalic acid And aromatic polyhydrazide compounds such as an aromatic dicarboxylic acid dihydrazide such as hydrazide. Among these, aliphatic dicarboxylic acid dihydrazide and alicyclic dicarboxylic acid dihydrazide are preferable, and aliphatic dicarboxylic acid dihydrazide having about 2 to 14 carbon atoms such as adipic acid dihydrazide is particularly preferable. A compound (A2) can be used individually or in combination of 2 or more.

  The compound (A2) reacts with the group (a1) in the acrylic copolymer (A1) to give a crosslinked structure to the polymer. Therefore, when the image receiving layer is formed from a composition containing the compound (A2) and the acrylic copolymer (A1), the hardness of the surface of the ink recording body is further improved, and the scratch resistance of the surface of the recording body is further improved.

[Inorganic fine particles (B)]
Examples of the inorganic fine particles (B) include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc hydroxide, zinc sulfide, zinc carbonate, Fine particles such as hydrosulfite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, dry silica, wet silica, sol-gel silica, colloidal silica, aluminum oxide, alumina sol, pseudoboehmite, litbon, zeolite, and aluminum hydroxide . Of these, dry silica, wet silica, sol-gel silica, colloidal silica, alumina sol, and the like are preferable because they are excellent in transparency and gloss when forming an image receiving layer (ink receiving layer) and can form fine voids. Can be used. These inorganic fine particles can be used alone or in combination of two or more.

  The shape of the inorganic fine particles (B) is not particularly defined and may be any of spherical, flat, columnar, beaded, etc. The average particle size of the inorganic fine particles (B) is, for example, 3 nm to 10 μm, preferably 10 to 200 nm, More preferably, it is 20-100 nm.

[Preparation of resin composition for ink recording medium]
The resin composition for an ink recording material of the present invention comprises the acrylic copolymer (A1) and inorganic fine particles (B), or the acrylic copolymer (A1) and compound (A2) and inorganic fine particles (B). Can be obtained. The blending ratio is not particularly limited. For example, the blending ratio (weight ratio) between the sum of (A1) and (A2) and the inorganic fine particles (B) is [(A1) + (A2) ] / (B) = 1/99 to 99/1, preferably [(A1) + (A2)] / (B) = 5/95 to 60/40, more preferably [(A1) + (A2)] / (B) = 10/90 to 30/70. Further, the mixing ratio of the acrylic copolymer (A1) and the compound (A2) is not particularly limited. For example, the compound (A2) 0 per 1 mol of the (a1) structure in the acrylic copolymer (A1). -5 mol (e.g. 0.1-5 mol), preferably 0-3 mol (e.g. 0.2-3 mol), more preferably 0-1 mol (e.g. 0.3-1 mol).

  If necessary, other hydrophilic polymer can be blended in the resin composition for ink recording medium. Examples of the hydrophilic polymer include hydrophilic natural polymers or derivatives thereof (starch, corn starch, sodium alginate, gum arabic, gelatin, casein, dextrin, etc.), cellulose derivatives (methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, Cellulose sulfate, cyanoethyl cellulose, etc.), polyalkylene oxide (polyethylene oxide, ethylene oxide-propylene oxide block copolymer, etc.), a polymer having a carboxyl group or a sulfonic acid group (including an acid anhydride group) or a salt thereof [ Ethylene-based polymers such as ethylene-maleic anhydride copolymer; poly (meth) acrylic acid or salts thereof (alkali metal salts such as ammonium salts and sodium), methyl methacrylate- Acrylic polymers such as (meth) acrylic acid copolymers and acrylic acid-vinyl alcohol copolymers; vinyl ether polymers such as methyl vinyl ether-maleic anhydride copolymers; styrene-maleic anhydride copolymers, styrene- (Meth) acrylic acid copolymers, styrene polymers such as sodium polystyrene sulfonate; sodium polyvinyl sulfonate, etc.], vinyl ether polymers (polyvinyl alkyl ethers such as polyvinyl methyl ether and polyvinyl isobutyl ether), containing nitrogen atoms Polymer (or cationic polymer) or salt thereof [quaternary ammonium salts such as polyvinylbenzyltrimethylammonium chloride and polydiallyldimethylammonium chloride, polydimethylaminoethyl (meth) acrylate hydrochloride, Vinylpyridine, polyvinyl imidazole, polyethylene imine, polyamide polyamine, polyacrylamide, polyvinyl pyrrolidone, etc.] and the like. These hydrophilic polymers can be used alone or in combination of two or more.

  The resin composition for an ink recording medium may contain a granular material (such as a pigment). Examples of the granular material include inorganic granular materials (white carbon, particulate calcium silicate, zeolite, magnesium aluminosilicate, calcined siliceous soil, particulate magnesium carbonate, particulate alumina, silica, talc, kaolin, deramikaolin, Clay, heavy calcium carbonate, light calcium carbonate, magnesium carbonate, titanium dioxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, magnesium silicate, calcium sulfate, sericite, bentonite, smectite, etc.) , Organic powder particles (crosslinked or non-crosslinked organic fine particles such as polystyrene resin, acrylic resin, urea resin, melamine resin, and benzoguanamine resin, and organic powder particles such as fine hollow particles). These powders can be used by selecting one or more kinds as appropriate. In addition, when using a granular material, the said acrylic copolymer (A1) and / or the said hydrophilic polymer can be used as binder resin. The ratio of the powder and binder resin is, for example, about 0.1 to 80 parts by weight, preferably about 0.2 to 50 parts by weight with respect to 100 parts by weight of the binder resin.

  In the resin composition for ink recording medium, conventional additives such as an antifoaming agent, a coating property improving agent, a thickener, a lubricant, a stabilizer (antioxidant, ultraviolet absorber, Heat stabilizers, etc.), antistatic agents, antiblocking agents and the like may be added.

  A solvent in the case where the resin composition for an ink recording medium is a dispersion or a solution is not particularly limited, and a wide range of solvents can be used, but it is often a water or a mixed solvent of water and a water-soluble organic solvent. .

  The resin composition for an ink recording medium can be prepared using a conventional apparatus. For example, a method in which the components constituting the resin composition for an ink recording medium are simply mixed using a stirring blade, a turbine stator type high-speed rotating stirring disperser (for example, a homogenizer, etc.), a colloid mill, an ultrasonic emulsifier And a method of mixing using a conventional disperser such as a high-pressure homogenizer. The acrylic copolymer (A1), the compound (A2) and the inorganic fine particles (B) are usually provided in the form of a dispersion (for example, an aqueous emulsion) or a solution (for example, an aqueous solution). One component can also be used in the form of a solid or a liquid free of solvent.

[Ink recording medium]
The ink recording material of the present invention has at least one image receiving layer (ink receiving layer) formed from the above resin composition for an ink recording material on at least one surface of a substrate. As the substrate, those generally used as the substrate (support) of the ink recording medium can be used, and for example, any of paper, plastic film, laminates thereof and the like may be used.

  The ink recording material of the present invention is obtained by using the resin composition for an ink recording material as it is or using the resin composition in an appropriate solvent (water, a hydrophilic solvent that may be water-soluble, a hydrophobic solvent, or a mixed solvent thereof). The coating solution obtained by dilution or solvent exchange in step 1) is applied to at least one surface of the substrate and dried. The coating solution can be applied by a conventional casting or coating method such as a roll coater, an air knife coater, a blade coater, a rod coater, a bar coater, a comma coater, a gravure coater, or a silk screen coater method. If necessary, after applying the coating solution, a crosslinked image-receiving layer may be formed by heating at an appropriate temperature selected from the range of about 40 to 150 ° C.

  The thickness of the image receiving layer formed from the resin composition for an ink recording medium can be selected depending on the application, and is, for example, 3 to 50 μm, preferably 6 to 30 μm, and more preferably about 5 to 30 μm.

  On the image receiving layer, other layers such as a porous layer, an antiblocking layer, a slipping layer, and an antistatic layer may be formed as necessary.

  The ink recording material of the present invention is useful as a recording sheet by an ink jet method for recording by ejecting small ink droplets, but is not limited thereto, and is a printing sheet (especially water-based ink) such as offset printing and flexographic printing. Sheet).

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Preparation Example 1 [Preparation of acrylic copolymer (A1-1)]
In a 2 L reaction vessel equipped with a stirrer, reflux condenser, dropping funnel, nitrogen inlet tube and thermometer, 44.55 parts by weight of isopropyl alcohol and 0.25 parts by weight of azobisisobutyronitrile were placed, and Heated. As monomer components, 44.5 parts by weight of methyl methacrylate, 2.5 parts by weight of diacetone acrylamide, and 3 parts by weight of dimethylaminoethyl methacrylate were mixed and dropped into the reaction vessel over 4 hours. After completion of the dropwise addition, 0.2 parts by weight of azobisisobutyronitrile and 5 parts by weight of isopropyl alcohol were added, and the reaction was further continued for 4 hours. After completion of the reaction, with stirring, 0.998 parts by weight of 88% by weight aqueous formic acid solution was added, and then 180 parts by weight of ion exchange water was added. Finally, isopropyl alcohol and water were distilled off from the reaction mixture to obtain an aqueous emulsion of acrylic copolymer (A1-1) (nonvolatile content: 25% by weight, pH: 4.0, viscosity at 23 ° C .: 130 mPa · s).

Preparation Example 2 [Preparation of acrylic copolymer (A1-2)]
The aqueous acrylic copolymer (A1-2) was prepared in the same manner as in Preparation Example 1 except that 42 parts by weight of methyl methacrylate, 5 parts by weight of diacetone acrylamide, and 3 parts by weight of dimethylaminoethyl methacrylate were used as monomer components. An emulsion was obtained (nonvolatile content: 25% by weight, pH: 4.5, viscosity at 23 ° C .: 130 mPa · s).

Preparation Example 3 [Preparation of acrylic copolymer (A1-3)]
As in the case of Preparation Example 1 except that 39.5 parts by weight of methyl methacrylate, 7.5 parts by weight of diacetone acrylamide, and 3 parts by weight of dimethylaminoethyl methacrylate were used as monomer components, an acrylic copolymer (A1- An aqueous emulsion of 3) was obtained (nonvolatile content: 25% by weight, pH: 4.5, viscosity at 23 ° C .: 400 mPa · s).

Preparation Example 4 [Preparation of acrylic copolymer (X)]
Preparation Example 1 except that 48 parts by weight of methyl methacrylate and 2 parts by weight of dimethylaminoethyl methacrylate were used as monomer components, and 0.665 parts by weight of an 88% by weight aqueous formic acid solution was added with stirring after the completion of the reaction. In the same manner, an aqueous emulsion of an acrylic copolymer (X) was obtained (nonvolatile content: 25 wt%, viscosity: 4.1, 23 ° C., viscosity: 450 mPa · s).

Example 1
10 parts by weight of an aqueous emulsion of the acrylic copolymer (A1-1) obtained in Preparation Example 1 is added to 90 parts by weight of colloidal silica [trade name “KLEBOSOL30CAL50” manufactured by Clariant Japan Co., Ltd.] while stirring. Thus, a coating solution was prepared. On a paper base material [Seiko Epson Co., Ltd., trade name “Photomat Paper”], the above coating solution was applied with a # 30 coater bar, and then dried at 100 ° C. for 3 minutes. An ink jet image-receiving film (ink recording material) having a dry coating thickness of 10 μm was obtained by sandwiching between SUS plates and hot pressing at 100 ° C.

Example 2
In Example 1, an inkjet image-receiving film was obtained in the same manner as in Example 1 except that 0.13 part by weight of a 10% by weight adipic acid dihydrazide aqueous solution was added to the prepared coating liquid (100 parts by weight) with stirring. It was.

Example 3
In Example 1, except that the same amount of the aqueous emulsion of the acrylic copolymer (A1-2) obtained in Preparation Example 2 was used instead of the aqueous emulsion of the acrylic copolymer (A1-1). In the same manner as in Example 1, an inkjet image-receiving film was obtained.

Example 4
In Example 3, an inkjet image-receiving film was obtained in the same manner as in Example 3 except that 0.26 parts by weight of a 10% by weight adipic acid dihydrazide aqueous solution was added to the prepared coating liquid (100 parts by weight) with stirring. It was.

Example 5
In Example 1, except that the same amount of the aqueous emulsion of the acrylic copolymer (A1-3) obtained in Preparation Example 3 was used instead of the aqueous emulsion of the acrylic copolymer (A1-1). In the same manner as in Example 1, an inkjet image-receiving film was obtained.

Example 6
In Example 5, an inkjet image-receiving film was obtained in the same manner as in Example 5 except that 0.39 parts by weight of a 10% by weight adipic acid dihydrazide aqueous solution was added to the prepared coating liquid (100 parts by weight) with stirring. It was.

Comparative Example 1
Example 1 is the same as Example 1 except that the same amount of the aqueous emulsion of the acrylic copolymer (X) obtained in Preparation Example 4 was used instead of the aqueous emulsion of the acrylic copolymer (A1-1). In the same manner, an ink jet image receiving film was obtained.

Evaluation test About the inkjet image-receiving film obtained in Examples and Comparative Examples, an evaluation test on scratch resistance was performed as follows. The results are shown in Table 1.

(Scratch resistance)
Using an ink-jet printer PM-950C manufactured by Seiko Epson Corporation, two ink-jet image-receiving films obtained in Examples and Comparative Examples are stacked and set under the photo matte paper, and the paper mode is set to PM photo paper. Then, two sheets of blue were continuously printed on the lower surface of the paper. The image printed on the second sheet was visually observed for the presence or absence of scratches and evaluated according to the following criteria.
A: Scratches are hardly confirmed by visual inspection.
○: Slight scratches can be confirmed.
Δ: Scratches can be clearly observed.
X: A remarkable abrasion can be confirmed.

Claims (4)

A resin composition for an ink recording medium comprising an acrylic copolymer (A1) copolymerized with a monomer having a structure represented by the following formula (a1) and inorganic fine particles (B) ,
The ratio of the monomer having the structure represented by the formula (a1) to the total monomer amount of the acrylic copolymer (A1) is 0.5 to 30% by weight,
The ratio of the nonionic monomer to the total monomer amount of the acrylic copolymer (A1) is 40 to 95% by weight,
The ratio of the cationic monomer to the total monomer amount of the acrylic copolymer (A1) is 1 to 30% by weight.
Resin composition for ink recording medium .

An acrylic copolymer (A1) obtained by copolymerizing a monomer having a structure represented by the following formula (a1) and a compound (A2) containing at least two structures represented by the following formula (a2); A resin composition for an ink recording medium comprising inorganic fine particles (B) ,
The ratio of the monomer having the structure represented by the formula (a1) to the total monomer amount of the acrylic copolymer (A1) is 0.5 to 30% by weight,
The ratio of the nonionic monomer to the total monomer amount of the acrylic copolymer (A1) is 40 to 95% by weight,
The ratio of the cationic monomer to the total monomer amount of the acrylic copolymer (A1) is 1 to 30% by weight.
Resin composition for ink recording medium .

  The resin composition for an ink recording medium according to claim 1 or 2, wherein the inorganic fine particles (B) are at least one selected from the group consisting of dry silica, wet silica, sol-gel silica, colloidal silica, and alumina sol.   An ink recording medium comprising at least one image-receiving layer formed from the resin composition for an ink recording medium according to any one of claims 1 to 3 on at least one surface of a substrate.