JP2007144754A - Resin composition for ink recording body and ink recording body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition for an ink recording body, in which develops neither falling off nor cracking of fine inorganic particles, highly lustrous and clear printed images are obtained, the surface scratchiness can be improved and, in addition, which has a high mechanical stability and the fine inorganic particle component of which hardly settle down and separate, and also to provide an ink recording body having an image receiving layer made of the composition. <P>SOLUTION: This composition for the ink-jet recording body consists of an acrylic copolymer (A) obtained by copolymerizing a monomer shown by formula (a) and fine inorganic particles (B). Further, on one side of a base material, one image receiving layer made of the resin composition for the ink recording body is provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resin composition for an ink recording material and an ink recording material. More specifically, the ink recording material resin composition improved not only in ink absorbability and water resistance but also improved in scratch resistance on the surface of the image receiving layer, and the ink recording material resin composition. The present invention relates to an ink recording medium 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 high gloss and clear printed images, to improve the scratching properties of the surface, and to have high mechanical stability and the inorganic fine particle components are precipitated. 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 an acrylic copolymer copolymerized with a specific monomer and inorganic fine particles has high mechanical stability in the form of a dispersion. In addition to the fact that the inorganic fine particle components are difficult to settle and separate, when the image receiving layer is formed, the inorganic fine particles do not fall off or crack, and a high gloss and clear printed image can be obtained. As a result, the present invention was completed.

（式中、Ｒ¹及びＲ²は同一または異なって水素原子またはメチル基であり、ｋは１〜６の整数、ｓは１〜１０の整数、ｍは２〜１２の整数、ｔは１〜２０の整数であり、ｋ、ｓがそれぞれ２以上の場合、Ｒ²は同一又は異なっていても良い）
で示される単量体を共重合させたアクリル共重合体（Ａ）と無機微粒子（Ｂ）からなるインクジェット記録体用組成物を提供する。 That is, the present invention provides the following formula (a):

Wherein R ¹ and R ² are the same or different and are a hydrogen atom or a methyl group, k is an integer of 1 to 6, s is an integer of 1 to 10, m is an integer of 2 to 12, and t is 1 to And when k and s are each 2 or more, R ² may be the same or different)
The composition for inkjet recording bodies which consists of the acrylic copolymer (A) which copolymerized the monomer shown by and inorganic fine particle (B) 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 also provides an ink recording material having at least one image-receiving layer formed from the above resin composition for an ink recording material on at least one surface of a substrate.

  According to the production method of the present invention, the inorganic fine particle component has high mechanical stability and is difficult to settle and separate, and the inorganic fine particles do not fall off or crack in the image receiving layer, and a high gloss and clear printed image can be obtained. And the scratch resistance of the surface can be improved.

[Acrylic copolymer copolymerized with monomer represented by formula (a)]
The acrylic copolymer (A) is not particularly limited as long as the monomer represented by the formula (a) is copolymerized.

  The monomer represented by the formula (a) is a primary hydroxyl group rich in reactivity with a (meth) acrylic double bond having radical polymerizability, a polylactone moiety imparting elasticity, and a curing agent in the molecule. Is included. As for the molecular weight of the monomer represented by the formula (a), for example, the number average molecular weight is about 200 to 10000 (preferably 200 to 5000, more preferably 200 to 1500). Typical examples of the monomer represented by the formula (a) include lactone-modified acrylic monomers such as γ-butyrolactone, δ-butyrolactone, δ-butyrolactone, and ε-caprolactone.

  The ε-caprolactone-modified acrylic monomers are, for example, trade names “Placcel FA-1”, “Placcel FA-2”, “Placcel FA-3”, “Placcel FA-4”, “Placcel” manufactured by Daicel Chemical Industries, Ltd. Commercial products such as “FA-5”, “Placcel FM-1”, “Placcel FM-2”, “Placcel FM-3”, “Placcel FM-4”, and “Placcel FM-5” are available.

  By using the acrylic copolymer obtained by copolymerizing the monomer represented by the formula (a), the elasticity of the surface of the ink jet recording body is improved, so that the friction when an external force is applied can be reduced. In addition, the inorganic fine particles in the image receiving layer can be prevented from falling off or cracking. For this reason, the scratch resistance of the surface of the recording material can be improved.

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

  The method for imparting cationicity to the acrylic copolymer (A) (method for 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- Onium base-containing polymerizable unsaturation such as ₄ alkyl ammonium halides] 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 for imparting anionic property to the acrylic copolymer (A) (method for introducing an anionic group) is not particularly limited. For example, a simple substance 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 (A) obtained by copolymerizing the monomer represented by the formula (a), 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 and diacetone (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 (medium ) Acrylate, a polyoxyalkylene group-containing monomer such as polyethylene glycol mono (meth) 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.

  In the case where an acrylic copolymer (A) obtained by copolymerizing the monomer represented by the formula (a) is synthesized by combining the above monomers, the use ratio of each monomer is particularly limited. However, for example, the ratio of the monomer represented by the formula (a) to the total monomer amount is 0.1 to 50% by weight (preferably 0.5 to 40% by weight, more preferably 1 to 30%). % By weight). Moreover, the ratio of the nonionic monomer with respect to the total amount of monomers is 30 to 99 weight%, for example, Preferably it is 35 to 97 weight%, More preferably, it is about 45 to 96 weight%. Furthermore, the ratio with respect to the monomer total amount of a cationic monomer or an anionic monomer is 1 to 60 weight%, for example, Preferably it is 3 to 50 weight%, More preferably, it is about 4 to 45 weight%.

Although the weight average molecular weight of the acrylic copolymer (A) obtained by copolymerizing the monomer represented by the formula (a) is not particularly limited, for example, about 1.0 × 10 ^{3 to} 1.0 × 10 ⁷ , Preferably it is about 5.0 * 10 < ³ > -5.0 * 10 < ⁵ >.

  As a polymerization method for obtaining the acrylic copolymer (A) obtained by copolymerizing the monomer represented by the formula (a), a known polymerization method such as emulsion polymerization can be used. After solution polymerization of each copolymer component in a suitable organic solvent, water is added to the obtained resin solution to emulsify, and the solvent used for solution polymerization is removed to obtain an aqueous resin composition, or A method of removing the organic solvent from the resin solution and then adding water to obtain an aqueous resin 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, the polymerization may be started by irradiation with 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 catalyst system comprising a combination of persulfate (for example, alkali metal salt, ammonium salt, etc.) and an oxidizing agent such as peroxide] etc. The polymerization initiators 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 15 hours, preferably 2 to 10 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 (A) obtained by copolymerizing the monomer represented by the formula (a) is obtained by emulsion polymerization, a general method for carrying out emulsion polymerization can be employed.

[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 have excellent transparency and gloss when forming an image receiving layer (ink receiving layer) and can form fine voids. Can be used. In particular, colloidal silica is preferably used because it can be easily dispersed in an aqueous emulsion of the acrylic copolymer (A) to obtain a uniform resin composition. 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 is obtained by blending an acrylic copolymer (A) obtained by copolymerizing the monomer represented by the formula (a) and inorganic fine particles (B). The blending ratio is not particularly limited, but is generally (A) 99 to 1% by weight, (B) 1 to 99% by weight, preferably (A) 60 to 5% by weight, ( B) 40 to 95% by weight, more preferably (A) 30 to 10% by weight, and (B) 70 to 90% by weight.

  If necessary, other hydrophilic polymer can be blended in the resin composition for ink recording medium. Examples of the other hydrophilic polymers 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, carboxy). Methyl cellulose, cellulose sulfate, cyanoethyl cellulose, etc.), polyalkylene oxide (polyethylene oxide, ethylene oxide-propylene oxide block copolymer, etc.), polymer having carboxyl group or sulfonic acid group (including acid anhydride group) or the like Salt [ethylene-based polymer such as ethylene-maleic anhydride copolymer; poly (meth) acrylic acid or a salt thereof (alkali metal salt such as ammonium salt and sodium), methacrylic acid Acrylic polymers such as chill- (meth) acrylic acid copolymer and acrylic acid-vinyl alcohol copolymer; vinyl ether polymers such as methyl vinyl ether-maleic anhydride copolymer; styrene-maleic anhydride copolymer , 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), Nitrogen atom-containing polymer (or cationic polymer) or a salt thereof [quaternary ammonium salt such as polyvinylbenzyltrimethylammonium chloride and polydiallyldimethylammonium chloride, polydimethylaminoethyl (meth) acrylate salt Salts, polyvinyl pyridine, 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 (A) 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 (A) and inorganic fine particles (B) obtained by copolymerizing the monomer represented by the formula (a) are usually in the form of a dispersion (for example, an aqueous emulsion) or a solution (for example, an aqueous solution), respectively. However, at least one of them can be used in the form of a solid.

[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.

で表されるε−カプロラクトン変性アクリルモノマー［商品名「プラクセルＦＭ３」、ダイセル化学工業（株）製：分子量４７２］５重量部、ジメチルアミノエチルメタクリレート２重量部を混合し、反応容器中に４時間かけて滴下した。滴下終了後、アゾビスイソブチロニトリル０．２重量部及びイソプロピルアルコール５重量部を添加し、さらに４時間反応を継続させた。反応終了後、撹拌しながら、８８重量％ギ酸水溶液０．９９８重量部を添加し、次いでイオン交換水を１８０重量部添加した。最後に、反応混合物よりイソプロピルアルコールおよび水を留去することにより、式（ａ）で表される単量体を共重合させたアクリル共重合体（A-1）の水性エマルジョンを得た（不揮発分２５重量％、ｐＨ４．２、２３℃での粘度１５０ｍＰａ・ｓ）。
調製例２［アクリル共重合体（Ｂ）の調製］
モノマー成分として、メチルメタクリレート４８重量部、ジメチルアミノエチルメタクリレート２重量部を用いた点、及び反応終了後、撹拌しながら、８８重量％ギ酸水溶液０．６６５重量部を添加した点以外は、調製例１と同様にして、アクリル共重合体（Ｂ）の水性エマルジョンを得た（不揮発分２５重量％、ｐＨ４．１、２３℃での粘度４５０ｍＰａ・ｓ）。 Preparation Example 1 [Preparation of Acrylic Copolymer (A-1) Copolymerized with Monomer Represented by Formula (a)]
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 a monomer component, 43 parts by weight of methyl methacrylate, the following formula (a-1)

5 parts by weight of ε-caprolactone-modified acrylic monomer [trade name “Placcel FM3”, manufactured by Daicel Chemical Industries, Ltd .: molecular weight 472] and 2 parts by weight of dimethylaminoethyl methacrylate are mixed for 4 hours. It was dripped over. 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-exchanged water was added. Finally, isopropyl alcohol and water were distilled off from the reaction mixture to obtain an aqueous emulsion of an acrylic copolymer (A-1) obtained by copolymerizing the monomer represented by the formula (a) (nonvolatile). Min. 25 wt%, pH 4.2, viscosity at 23 ° C. 150 mPa · s).
Preparation Example 2 [Preparation of acrylic copolymer (B)]
Preparation Example, 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 88% by weight aqueous formic acid solution was added with stirring after the reaction was completed. In the same manner as in Example 1, an aqueous emulsion of an acrylic copolymer (B) was obtained (nonvolatile content: 25 wt%, viscosity: 4.1, 23 ° C., viscosity: 450 mPa · s).

Example 1
An acrylic copolymer obtained by copolymerizing the monomer represented by the formula (a) obtained in Preparation Example 1 with 90 parts by weight of colloidal silica silica [manufactured by Clariant Japan Co., Ltd., trade name “KLEBOSOL30CAL50”] A coating solution was prepared by adding 10 parts by weight of the aqueous emulsion A-1) with stirring. The above coating solution was applied with a # 30 coater bar on a paper substrate [Seiko Epson Co., Ltd., trade name “Photomat Paper”], and then dried at 100 ° C. for 3 minutes. An ink-jet image receiving film (ink recording material) having a dry coating thickness of 5 μm was obtained by sandwiching between SUS plates and hot pressing at a temperature of 100 ° C.

Comparative Example 1
Instead of the aqueous emulsion of the acrylic copolymer (A-1) obtained by copolymerizing the monomer represented by the formula (a) in Example 1, the acrylic copolymer (A An inkjet image-receiving film was obtained in the same manner as in Example 1 except that the same amount of -2) was used.
Evaluation test About the inkjet image-receiving film obtained in Examples and Comparative Examples, an evaluation test on scratch resistance was performed as follows.

(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 were stacked and set, and the paper mode was set to PM photographic paper. Was printed on one side of the paper. With respect to the image printed on the second sheet, the presence or absence of scratches was observed with the naked eye. As a result, no scratches could be visually confirmed with the ink recording medium of Example 1, but there was a clear scratch with the ink recording medium of Comparative Example 1. It was confirmed in several places.

Claims (3)

The following formula (a)

Wherein R ¹ and R ² are the same or different and each represents a hydrogen atom or a methyl group, k is an integer of 1 to 6, s is an integer of 1 to 10, m is an integer of 2 to 12, and t is 1 to 6. It represents an integer of 20. When k and s are each 2 or more, R ² may be the same or different.
A composition for an ink jet recording material comprising an acrylic copolymer (A) obtained by copolymerizing the monomer represented by formula (A) and an inorganic fine particle (B).   The resin composition for an ink recording material according to claim 1, 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 claim 1 or 2 on at least one surface of a substrate.