JP2002103794A - Ink jet recording resin composition and recording sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording resin composition for obtaining an ink acceptive layer having excellent mechanical stability of a coating liquid used to form an ink acceptive layer, fresh, high ink absorbability, dryability, glossiness and water resistance, and a recording sheet using the composition. SOLUTION: The recording sheet comprises the ink acceptive layer formed by using an ink jet recording resin composition obtained by adding an aqueous solvent of 100 to 2,000 pts.wt. to a solid content of 100 pts.wt., containing a binder resin of 3 to 60 pts.wt. of an acrylic copolymer obtained by copolymerizing a polymerizable unsaturated monomer having a hydrolyzable silyl group and another polymerizable unsaturated monomer and inorganic fine particles of 97 to 40 wt.% and forming the ink acceptive layer by using the composition on the base.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for ink-jet recording and a recording sheet, and more particularly, to a coating liquid used for forming an ink-receiving layer which has excellent mechanical stability and which is clear and high in ink. The present invention relates to a resin composition for ink jet recording capable of obtaining an ink receiving layer having absorptivity, drying property, glossiness and water resistance, and a recording sheet having an ink receiving layer formed using the same.

[0002]

2. Description of the Related Art Ink jet recording systems have been rapidly spreading in recent years because they are inexpensive, can be easily made full color, have low noise, and have excellent print quality. In the inkjet recording, a water-based ink is mainly used in terms of safety and recording suitability, and recording is performed by flying ink dots from a nozzle toward a recording sheet. For this reason, the recording sheet is required to quickly absorb the ink. Further, by increasing the number of colors of the ink and reducing the particle diameter of the ink dots, it has become possible to obtain recording comparable to silver halide photographic images, and the recording speed has been increased. As described above, the recording apparatus and the recording method have been improved, and accordingly, a high degree of characteristics has been required for the ink jet recording material.

Various recording papers have been conventionally used as ink jet recording materials. For example, plain paper,
Coated paper (art paper, coated paper, cast-coated paper, etc.), and in addition to these papers, various substrates such as transparent or opaque plastic films, synthetic paper, and RC paper coated on both sides with plastic A recording sheet provided with an ink receiving layer is used.

As the ink receiving layer, a so-called swelling type ink receiving layer mainly composed of a water-soluble or hydrophilic resin such as polyvinyl alcohol, and a void layer mainly formed of a fine particle component such as silica are used. , A so-called void type ink receiving layer. As these ink receiving layers, for example, JP-A-63
Japanese Patent Application Laid-Open No. 115780/1999 contains synthetic silica (meth)
A polymer having a skeleton of an alkyl acrylate quaternary ammonium salt and / or a (meth) acrylamidoalkyl quaternary ammonium salt is disclosed in JP-A-6-227114. A pigment containing fine silica and a zwitterionic latex are mainly used. And those formed from aqueous compositions.

[0005] An ink jet recording material having a swelling type ink receiving layer has a silver salt of extremely high gloss and color density after the ink solvent composed of water and a high-boiling organic solvent (such as glycerin or ethylene glycol) is completely evaporated. This has the advantage that an image having a photographic feel can be obtained, but the ink absorption rate (drying rate) is slower than that of the void type ink receiving layer, and in some cases, several hours after printing due to the effect of the high boiling point solvent in the ink solvent The ink receiving layer remains swollen and wet for several days from the beginning, and has a disadvantage that it cannot be sticky or overlapped. In addition, in a portion where the amount of printing ink is large, there is a problem that an image defect such as beading occurs due to insufficient ink absorbency, and it is difficult to achieve both ink absorbency and water resistance. In particular, as the quality of the image is increased, such as by increasing the speed of a printer, using a photo ink, or printing at a high resolution of 1000 dpi or more, the ink absorption speed (drying speed) becomes slower. It is becoming mainstream.

On the other hand, an ink jet recording material having a void type ink receiving layer exhibits high ink absorbency because the voids absorb ink. For this reason, image defects such as beading are unlikely to occur, and the water resistance is high because of using water-insoluble inorganic fine particles as a main component. In addition, if the thickness of the ink receiving layer is set so that sufficient ink absorption capacity can be secured, even if the ink solvent such as a high boiling point organic solvent remains in the voids, the surface is apparently dry immediately after printing. And has a drying rate that can be touched and overlapped. However, despite such advantages, there is a problem that gloss is too low due to the presence of voids.

The above-mentioned void-type ink receiving layer is described in, for example, JP-A-60-219084 and JP-A-63-1.
7,0074, JP-A-2-43083, JP-A-4-9328
4, No. 7, 137431, and No. 8-197832, which disclose various inorganic particles. The coating liquid for forming such a void-type ink receiving layer on a base material may have a void formed between the inorganic fine particles if the binder content relative to the inorganic fine particles is excessively increased in order to increase gloss. Depending on the properties of the binder resin, the resin swells with the ink solvent and closes the voids, resulting in insufficient ink absorbency. Therefore, a formulation with a low binder resin content is used. However, if the ratio of the inorganic fine particles is excessively increased in order to secure the ink absorbency and the absorption capacity, the strength of the coating film forming the ink receiving layer decreases and becomes brittle, and the inorganic fine particles may fall off or crack. As a result, a surface having high flatness cannot be formed, and a clear printed image cannot be obtained. Also, when the ratio of inorganic fine particles is increased,
Due to poor mechanical stability of the coating solution, there is also a production problem that the inorganic fine particles settle and separate during the production of the coating solution. Therefore, there is a need for the development of a resin composition for ink jet recording, which is excellent in the mechanical stability of a coating liquid and provides an ink receiving layer having ink absorbency (drying property) and gloss, and a recording sheet using the same. Was.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the conventional resin composition for void-type ink jet recording by improving the mechanical stability of a coating solution used for forming an ink receiving layer. An object of the present invention is to provide a resin composition for ink jet recording, which is excellent, is clear, and provides an ink receiving layer having high ink absorbency, drying properties, glossiness and water resistance, and a recording sheet using the same.

[0009]

Means for Solving the Problems In view of the above-mentioned problems, the present inventors have conducted intensive studies, and as a result, specified as a binder resin in a recording resin composition containing a binder resin, inorganic fine particles and an aqueous solvent. The present inventors have found that this problem can be solved by adopting the acrylic copolymer described above and setting the content of each of these components at a specific ratio, thereby completing the present invention.

That is, according to the first aspect of the present invention,
In the recording resin composition containing the binder resin (A), the inorganic fine particles (B) and the aqueous solvent (C), the binder resin (A) is a polymerizable unsaturated monomer (a) having a hydrolyzable silyl group. ) An acrylic copolymer (c) obtained by copolymerizing 0.5 to 15% by weight and 99.5 to 85% by weight of another polymerizable unsaturated monomer (b), and
The aqueous solvent (C) is contained at a ratio of 100 to 2000 parts by weight based on 100 parts by weight of a solid component composed of 3 to 60% by weight of the binder resin (A) and 97 to 40% by weight of the inorganic fine particles (B). The present invention provides a resin composition for inkjet recording characterized by the following.

According to the second aspect of the present invention, the first aspect is provided.
In the invention, the acrylic copolymer (c) is an aqueous resin composition obtained by adding water to a resin solution obtained by solution polymerization, emulsifying the resin solution, and then removing a polymerization solvent. A recording resin composition is provided.

Further, according to the third invention of the present invention, in the first invention, the inorganic fine particles (B) are added to the first solution which is a resin solution of the acrylic copolymer (c) obtained by solution polymerization. An aqueous resin composition obtained by adding a second solution, which is an aqueous solution containing, to emulsify and then removing a polymerization solvent contained in the first solution, wherein the resin is an aqueous resin composition. A composition is provided.

According to the fourth aspect of the present invention, the first aspect is provided.
In the invention of the above, the acrylic copolymer (c) is prepared by combining a polymerizable unsaturated monomer (a) having a hydrolyzable silyl group with another polymerizable unsaturated monomer in the presence of the inorganic fine particles (B). (B) is a resin composition obtained by copolymerizing the same with (b).

Further, according to a fifth aspect of the present invention, in the first aspect, the mechanical stability test according to JIS K 6392 is characterized in that the resin composition is stable under a load of 15 kgf. Is provided.

Further, according to the sixth aspect of the present invention, the first aspect is provided.
In the invention, the inorganic fine particles (B) are colloidal silica, and a resin composition for inkjet recording is provided.

Further, according to a seventh aspect of the present invention, there is provided an ink receiving layer formed of the resin composition for ink jet recording obtained according to any one of the first to sixth aspects on a substrate. A recording sheet is provided.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. 1. Binder resin (A) (a) Polymerizable unsaturated monomer having hydrolyzable silyl group The acrylic copolymer (c) used as the binder resin (A) of the present invention has a hydrolyzable silyl group. Use is made of a polymerizable unsaturated monomer (a) copolymerized with another polymerizable unsaturated monomer (b). As the polymerizable unsaturated monomer (a) having a hydrolyzable silyl group,
For example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, vinylmethoxydimethylsilane, vinylethoxydimethylsilane, vinylisobutoxydimethylsilane, vinyldimethoxymethylsilane, vinyldiethoxymethylsilane, vinyltris (β-methoxyethoxy) ) Silane, vinyldiphenylethoxysilane, vinyltriphenoxysilane, γ-
(Vinylphenylaminopropyl) trimethoxysilane, γ- (vinylbenzylaminopropyl) trimethoxysilane, γ- (vinylphenylaminopropyl) triethoxysilane, γ- (vinylbenzylaminopropyl) triethoxysilane, divinyldimethoxysilane,
Divinyldiethoxysilane, divinyldi (β-methoxyethoxy) silane, vinyldiacetoxymethylsilane,
Vinyltriacetoxysilane, vinylbis (dimethylamino) methylsilane, vinylmethyldichlorosilane, vinyldimethylchlorosilane, vinyltrichlorosilane,
Vinylmethylphenylchlorosilane, allyltriethoxysilane, 3-allylaminopropyltrimethoxysilane, allyldiacetoxymethylsilane, allyltriacetoxysilane, allylbis (dimethylamino) methylsilane, allylmethyldichlorosilane, allyldimethylchlorosilane, allyltrichlorosilane, Allylphenyldichlorosilane, β- (meth) acryloxyethyltrimethoxysilane, β- (meth) acryloxyethyltriethoxysilane, γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acryloxypropyltri Ethoxysilane, γ- (meth) acryloxypropylmethyldimethoxysilane, γ- (meth) acryloxypropylmethyldichlorosilane, γ- (meth) acryloxypropyltris (β -Methoxyethoxy) silane and the like. Preferably, it is a polymerizable unsaturated compound having an alkoxysilyl group (a _C1-4 alkoxysilyl group such as a methoxysilyl group and an ethoxysilyl group).

(B) Other polymerizable unsaturated monomers The acrylic copolymer (c) used as the binder resin (A) of the present invention includes a polymerizable unsaturated monomer having a hydrolyzable silyl group. A copolymer obtained by copolymerizing the monomer (a) and another polymerizable unsaturated monomer (b) is used. As the other polymerizable unsaturated monomer (b), at least one kind is preferably used. Is used as a copolymerization component. By using this monomer as a component for copolymerization, the resulting polymer has an ion-forming group, and the polymer can be easily emulsified.

Examples of the ion-forming group include a cation-forming group such as an amino group and an imino group, and an anion-forming group such as a carboxyl group. Examples of the polymerizable unsaturated monomer having a cation-forming group include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylaminopropyl (meth) acrylate, and dimethylamino. Ethyl (meth) acrylamide, (meth) acryloyloxyethyltrimethylammonium chloride, (meth) acryloyloxyethyltrimethylammonium sulfate and the like can be mentioned. Monomers having such a cation-forming group include
They can be used alone or in combination of two or more.

Examples of the polymerizable unsaturated monomer having an anion-forming group include 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) acryl sulfonic acid [(meth) acrylic] Sulfoethyl acid, sulfopropyl (meth) acrylate], (meth) acrylamidosulfonic acid [such as 2-acrylamido-2-methylpropanesulfonic acid] and the like. Such monomers having an anion-forming group can be used alone or in combination of two or more.

The acrylic copolymer (c) of the present invention uses the remainder of the polymerizable unsaturated monomer (a) having a hydrolyzable silyl group and the other polymerizable unsaturated monomer (b). And copolymerized. As the other polymerizable unsaturated monomer (b), a polymerizable unsaturated monomer having at least one kind of ion-forming group, for example, 1
It is preferable to use a monomer containing from 20 to 20% by weight, particularly from 2 to 10% by weight.

As the above monomer (b), at least 1
When a polymerizable unsaturated monomer other than a polymerizable unsaturated monomer having a type of ion-forming group is used as a copolymer component,
The polymerizable unsaturated monomer is appropriately selected from known polymerizable unsaturated monomers according to the use to which the resin composition is applied.

Examples of the polymerizable unsaturated monomer (b) include (meth) acrylic monomers, aromatic vinyls, vinyl esters, halogen-containing vinyls, and vinyl ethers (for example, vinyl Ethyl ether),
Vinyl ketones (for example, methyl vinyl ketone, etc.),
Vinyl heterocyclic compounds (for example, N-vinyl compounds such as N-vinylpyrrolidone and N-vinylimidazole;
N-vinylpyridine and the like; olefin-based monomers (eg, ethylene and propylene); allyl compounds (eg, allyl esters such as allyl acetate). This polymerizable unsaturated monomer (b) can be used alone or in combination of two or more.

(Meth) of the above polymerizable unsaturated monomer (b)
The acrylic monomer includes, for example, (meth) acrylate, (meth) acrylamides, (meth) acrylonitrile, and the like. (Meth) acrylates include, for example, alkyl (meth) acrylates [eg, methyl (meth) acrylate, ethyl (meth) acrylate,
Propyl (meth) acrylate, isopropyl (meth)
C such as acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and lauryl (meth) acrylate
_{1 over 18} alkyl (meth) acrylate, etc.], cycloalkyl (meth) acrylates [e.g., cyclohexyl (meth) acrylate, etc.], aryl (meth) acrylates [e.g., phenyl (meth) acrylate], aralkyl (meth) acrylate [ for example, benzyl (meth) acrylate, etc.], hydroxyalkyl (meth) acrylates [e.g., 2-hydroxyethyl, 2-hydroxypropyl (hydroxyethyl (meth) -C _{2 -4} alkyl (meth) acrylates such as acrylate etc.], glycidyl (Meth) acrylate, dialkylamino-alkyl (meth) acrylate [for example, 2
-(Dimethylamino) ethyl (meth) acrylate, 2
- (diethylamino) ethyl (meth) di C _{1 - 4} alkylamino -C _{2 - 4} alkyl, such as acrylates (meth)
Acrylate, etc.].

(Meth) acrylamides include, for example,
(Meth) acrylamide, hydroxyalkyl (meth)
Acrylamide, [for example, N-hydroxy-C _1-4 alkyl (meth) acrylamide such as N-methylol (meth) acrylamide, etc.], alkoxyalkyl (meth) acrylamide, [for example, N-hydroxymethyl (meth) acrylamide, etc. C _1-4 alkoxy-C _1-4 alkyl (meth) acrylamide], diacetoxy (meth) acrylamide and the like.

Preferred (meth) acrylic monomers include, for example, (meth) acrylates [eg, C
_{1 over 18} alkyl (meth) acrylate, hydroxy -
C _2-4 alkyl (meth) acrylate, glycidyl (meth) acrylate, di C _1-4 alkylamino-C
_2-4 alkyl (meth) acrylate, etc.], (meth)
Acrylamides and the like. Further, preferred (meth) acrylic monomers include C _2-10 alkyl acrylate, C _1-6 alkyl methacrylate,
Hydroxy-C _2-3 alkyl (meth) acrylate,
Glycidyl (meth) acrylate, di-C _1-3 alkylamino-C _2-3 alkyl (meth) acrylate and the like can be mentioned.

The aromatic vinyls include, for example, styrene,
α-methylstyrene, vinyltoluene and the like are included, and styrene is often used. Vinyl esters include, for example, vinyl acetate, vinyl propionate, vinyl versatate (VeoVa), and the like. Halogen-containing vinyls include, for example, vinyl chloride, vinylidene chloride, and the like. Further, as the polymerizable unsaturated monomer (b) other than the polymerizable unsaturated monomer having at least one kind of ion-forming group, the above-mentioned polymerizable unsaturated monomer having a hydrolyzable silyl group ( a) may be used.

As such a polymerizable unsaturated monomer (b), a hard monomer [for example, a glass transition temperature of 80 to 120 of methyl (meth) acrylate, styrene, etc.] is usually used.
° C. (in particular 90 to 105 ° C.) and the monomer component forming the homopolymer of the order, the soft monomer [e.g., a glass transition temperature -8 such as acrylic acid C _{2 -10} alkyl ester
Monomer component that forms a homopolymer at about 5 ° C. to 10 ° C. (particularly −85 ° C. to −20 ° C.)].

As described above, when a hard monomer and a soft monomer are usually used as the polymerizable unsaturated monomer (b), the mixing ratio thereof is not particularly limited. For example, 10 to 90% by weight of the hard monomer (for example, 15-85% by weight, preferably 20-80% by weight, more preferably 25-75% by weight, especially 30-70% by weight, soft monomer 10-90% by weight (for example, 15-85% by weight,
Preferably 20 to 80% by weight, more preferably 25 to 80% by weight.
75% by weight, especially 30 to 70% by weight).

In the acrylic copolymer (c) of the present invention,
Each of the above copolymerizable components is composed of 0.5 to 15% by weight of a polymerizable unsaturated monomer containing a hydrolyzable silyl group and another polymerizable unsaturated monomer containing a polymerizable unsaturated monomer containing an ion-forming group. Solution polymerization is carried out using 99.5 to 85% by weight of the saturated monomer (b).

The hydrolyzable silyl group-containing polymerizable unsaturated monomer (a) comprises 0.5 to 1 of all polymerizable unsaturated monomers.
5% by weight is used, preferably 1 to 12% by weight, particularly preferably 2 to 10% by weight. If the proportion of the monomer (a) is less than 0.5% by weight, there may be a problem that the water resistance and the strength of the coating film are deteriorated. on the other hand,
If it exceeds 15% by weight, there may be a problem that the polymerization stability of the acrylic copolymer (c) and the storage stability when emulsified are reduced.

The polymerizable unsaturated monomer (b) containing a polymerizable unsaturated monomer containing an ion-forming group is used in an amount of 85 to 99.5% by weight of the total polymerizable unsaturated monomer. It is preferably used in an amount of 88 to 99% by weight, particularly preferably 90 to 98% by weight. When the proportion of the monomer (b) is less than 85% by weight,
The polymerization stability of the acrylic copolymer (c) and the storage stability when emulsified are reduced. On the other hand, if it exceeds 99.5% by weight, the water resistance and the strength of the coated film are deteriorated.

In the present invention, various known polymerization methods such as emulsion polymerization can be used. However, each of the above-mentioned copolymer components is subjected to solution polymerization, and the emulsion is obtained by adding water to the obtained resin solution. Thereafter, a method of removing the solvent used for the solution polymerization to obtain an aqueous resin composition is preferably used. That is, the above copolymer components are mixed and copolymerized in the presence of a suitable organic solvent, and the polymer is alkali (for example, an alkylamine such as triethylamine,
Cyclic amines such as morpholine, alkanolamines such as triethanolamine, pyridine, ammonia, etc.)
And acids [eg, inorganic acids (eg, hydrochloric acid, sulfuric acid, etc.), organic acids (eg, carboxylic acids such as acetic acid, propionic acid, etc.)
Sulfonic acid, etc.). The polymerization operation may be a batch type or a continuous type.

The organic solvent used in the solution polymerization includes, for example, alcohols (eg, ethanol, isopropanol, n-butanol, etc.) and 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.), and the like can be used. These organic solvents may be used alone or in combination of two or more. As the organic solvent, an alcohol such as isopropanol, an aromatic hydrocarbon such as toluene, and a ketone such as methyl ethyl ketone are usually used.

The amount of the organic solvent used is not particularly limited. For example, the amount of the organic solvent relative to the total amount of the polymerizable unsaturated monomers is (0.1 / 1 to 5/1) by weight, and preferably (0/1). .5
/ 1 to 2/1).

In the solution polymerization, the polymerization may be started by irradiation with an electron beam or ultraviolet rays, but the polymerization is often started using a polymerization initiator. Examples of the polymerization initiator include, for example, azo compounds [for example, azobisisobutyronitrile, 2,2-azobis (2,4-dimethylvaleronitrile, azobiscyanovaleric acid), 2,2-azobis (2-amidinopropane) hydro Chloride, 2,2-azobis (2-amidinopropane) acetate, etc.], inorganic peroxides (for example, potassium persulfate, sodium persulfate,
Persulfates such as ammonium persulfate, hydrogen peroxide, etc.), organic peroxides [for example, benzoyl peroxide, di-
t-butyl peroxide, cumene hydroxy peroxide, di (2-ethoxyethyl) peroxydicarbonate, etc.] and a redox catalyst [for example, sulfite or bisulfite (for example, alkali metal salt, ammonium salt, etc.), L-ascorbin] A catalyst system comprising a combination of a reducing agent such as an acid or erythorbic acid and an oxidizing agent such as a persulfate (eg, an alkali metal salt or an ammonium salt) or a peroxide]. The polymerization initiators can be used alone or in combination of two or more.

The amount of the polymerization initiator used is, for example, from 0.001 to 20% by weight based on the total weight of the polymerizable unsaturated monomers,
Preferably 0.01 to 10% by weight (for example, 0.1 to 1%)
0% by weight).

The reaction temperature in the solution polymerization is, for example, 5
The temperature is 0 to 150 ° C, preferably about 70 to 130 ° C.
The reaction time is, for example, about 1 to 10 hours, preferably about 2 to 7 hours. The end point of the polymerization is determined by the absorption of a double bond (1648c
It can be confirmed by disappearance of m ^-1 ) or reduction of unreacted monomer by using gas chromatography.

When the polymer contains a cationic group such as an amino group, an imide group or another cation-forming group, the use of an acid enhances the hydrophilicity and easily dissolves or emulsifies the polymer. can do. Such acids include:
For example, inorganic acids (eg, hydrochloric acid, phosphoric acid, sulfuric acid, nitric acid, etc.), organic acids [eg, saturated aliphatic monocarboxylic acids such as formic acid, acetic acid, propionic acid, etc .; saturated aliphatic polycarboxylic acids such as oxalic acid, adipic acid, etc. Acids, unsaturated aliphatic polycarboxylic acids such as (meth) acrylic acid; unsaturated aliphatic polycarboxylic acids such as maleic acid and itaconic acid; aliphatic oxycarboxylic acids such as lactic acid and citric acid].

When the polymer has an acidic group such as a carboxyl group, the use of a base can easily dissolve or emulsify the polymer. Such bases include, for example, organic bases (eg, alkylamines such as triethylamine, cyclic amines such as morpholine, alkanolamines such as triethanolamine, pyridine, etc.), and inorganic bases (eg, ammonia, alkali metal hydroxides) Such)
And so on. The amount of the base used can be selected, for example, from the range of about 0.3 / 1 to 1.5 / 1 (molar ratio) of the base / acid group based on the total amount of the acid groups.

Further, such an acrylic copolymer (c)
When the copolymerization is carried out, from the viewpoint of improving the mechanical stability of the coating solution, the copolymerization may be performed in the presence of part or all of the inorganic fine particles (B) to be mixed in the coating solution. The amount of the inorganic fine particles (B) to be present in the polymerization solution is
It is preferably 3 to 80 parts by weight, particularly preferably 5 to 100 parts by weight based on the total weight of the polymerizable unsaturated monomer contained.
-30 parts by weight.

The emulsification of the polymer obtained by the solution polymerization is as follows:
It can be performed in the presence or absence of an organic solvent.
When the polymer is dissolved or emulsified and dispersed in the presence of an organic solvent, a water-soluble organic solvent (for example, an alcohol such as isopropanol) is often used as the organic solvent. When the polymer is emulsified in the presence of an organic solvent, the organic solvent may be removed after the emulsification by evaporation or the like, and the emulsion may contain an organic solvent. When the organic solvent is removed before emulsifying the polymer, a low-boiling organic solvent (for example, a ketone such as methyl ethyl ketone) is often used.

When the polymer obtained by the solution polymerization is emulsified in the presence of an organic solvent, an additive (eg, an emulsifier, a pH adjuster, an acid, etc.) is added to the organic solution containing the polymer, and then added to water. Can be added to emulsify. In this case, it is preferable that water is gradually added by dropping or the like. The temperature at the time of emulsification is preferably low, for example, 5 to 70 ° C,
Preferably, it can be selected from a range of about 10 to 50 ° C. The removal of the organic solvent after emulsification by adding water can be performed by, for example, 5
At a temperature of about ~ 80 ° C, under normal pressure or reduced pressure (for example,
(At about 0.0001 to 1 atm) in many cases.

In this case, from the viewpoint of improving the mechanical stability of the coating solution, the inorganic fine particles (B) mixed in the coating solution
May be mixed with water to be added. The content of the inorganic fine particles (B) mixed in the water to be added is preferably 3 to 70% by weight, particularly preferably 10 to 70% by weight.
50% by weight.

In the solution polymerization, a chain transfer agent such as alcohols such as catechol, thiols, and mercaptans (for example,
n-Lauryl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane) and the like may be used.

The average particle size of the polymer particles in the aqueous emulsion thus obtained is in a range that does not impair the dispersion stability, adhesion, etc., for example, 0.01 to 2 μm.
Preferably 0.01-1 μm, more preferably 0.01
To 0.5 μm, still more preferably 0.01 to 0.3
It can be selected from a range of about μm.

The aqueous resin composition obtained by emulsifying the acrylic copolymer (c) of the present invention may be an aqueous solution or an aqueous emulsion (aqueous polymer emulsion).
Such an aqueous resin composition is an aqueous resin composition formed without using a special cross-linking resin such as a cross-linked product of an acrylic silicone oligomer containing a hydrolyzable alkoxysilyl group. Is high.
In addition, by using this water-based resin composition, it is possible to obtain a coating agent with less fear of air pollution, poisoning, fire and the like, and with good workability.

The acrylic copolymer (c) of the present invention may contain, if necessary, a stabilizer such as a lubricant, an antioxidant, a light stabilizer, an ultraviolet absorber, a heat stabilizer, and the like. Various known additives such as a trapping agent, a quencher, an antistatic agent, a plasticizer, a thickener, and a defoaming agent may be added.

Light stabilizers and ultraviolet absorbers such as hindered amine compounds, benzoate compounds, benzotriazoles, benzophenones and formamidines are effective for imparting and improving weather resistance.

2. Inorganic fine particles (B) As the inorganic fine particles (B) used in the present invention, for example,
Examples include alumina, silica, calcium carbonate, aluminum hydroxide, and calcium silicate. Preferred is silica, and particularly preferred is colloidal silica. For the gloss and transparency of the ink receiving layer, those having a small particle size are preferred. For example, 1 to 500 nm, preferably 2 to 1
00 nm, more preferably 3 to 30 nm. The shape of the inorganic fine particles may be any of a spherical shape, a flat shape, a column shape, and a bead shape.

3. Aqueous Solvent (C) As the aqueous solvent (C) used in the present invention, various known solvents such as water and alcohols can be used, but water or a mixed solvent containing water as a main component is preferably used.

The thus obtained binder resin (A), the inorganic fine particles (B) and the aqueous solvent (C) are mixed to prepare a coating liquid used for forming the ink receiving layer.
As a mixing method, a conventionally known method can be used.
The mixing ratio is such that the aqueous solvent (C) is 100 to 20 parts by weight per 100 parts by weight of the solid component composed of 3 to 60% by weight of the binder resin (A) and 97 to 40% by weight of the inorganic fine particles (B).
00 parts by weight. Preferably, the binder resin (A)
The aqueous solvent (C) is 150 to 1000 parts by weight based on 100 parts by weight of a solid component comprising 5 to 30% by weight and 95 to 70% by weight of the inorganic fine particles (B).

In the above resin composition as a solid component, when the amount of the inorganic fine particles (B) exceeds 97% by weight (when the amount of the binder resin (A) is less than 3% by weight), a tendency of a decrease in film forming property is observed. On the other hand, if less than 40% by weight,
(If the amount of the binder resin (A) is more than 60% by weight), the quick-drying property and the ink absorbency are reduced. Further, a solid component 10 comprising a binder resin (A) and inorganic fine particles (B)
If the amount of the aqueous solvent (C) is less than 100 parts by weight with respect to 0 parts by weight, the storage stability decreases due to the sedimentation of the binder resin (A) and the inorganic fine particles (B). On the other hand, if it exceeds 2,000 parts by weight, it is difficult to form a coating film having a sufficient thickness, and the drying load increases, resulting in a decrease in productivity.

The ink receiving layer may contain, if necessary, other components such as a polymer having no crosslinkable group or an aqueous emulsion containing the polymer (eg, an ethylene-vinyl acetate copolymer emulsion, acetic acid Vinyl emulsion, etc.).

The ink receiving layer may contain a powder (eg, a pigment). Here, as the powder, for example, inorganic powder (white carbon, fine-particle calcium silicate, zeolite, magnesium aminosilicate, calcined silica, fine-particle magnesium carbonate, fine-particle alumina,
Talc, kaolin, deramikaolin, clay, heavy calcium carbonate, light calcium carbonate, magnesium carbonate,
Titanium dioxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, magnesium silicate, calcium sulfate, mineral powders such as sericite, bentonite, scumite, etc.), organic powders (polystyrene resin, urea resin, melamine resin) Or crosslinked or non-crosslinked organic fine particles such as benzoguanamine resin, and organic powders such as fine hollow particles. These powders are 1
Species or two or more species can be appropriately selected and used in combination.

In the case of using a powdery or granular material, a hydrophilic polymer such as a saponified vinyl acetate copolymer can be used as the binder resin. The ratio of the granular material to the binder resin is 0.1 to 80 parts by weight, preferably about 0.2 to 50 parts by weight, based on 100 parts by weight of the binder resin.

The coating liquid used for forming the ink receiving layer includes:
In addition, conventional ink fixing agents, cross-linking agents, light stabilizers, UV absorbers, anti-blocking agents, film forming aids, etc., as well as improvements in ink jet recording properties, storage stability of recording materials, and coating liquid properties, as long as properties are not lost. Additives for such purposes may be blended. The coating liquid comprising the resin composition for inkjet recording of the present invention has excellent mechanical stability. For example, J
The mechanical stability test of IS K 6392 is stable under a load condition of 15 kgf. Preferably, it is stable even under a load condition of 25 kgf.

4. In the present invention, the substrate on which the ink receiving layer is formed on the surface may be opaque, translucent or transparent depending on the application,
A substrate used for an overhead projector (OHP) or the like is usually transparent. The material of the substrate is not particularly limited, and examples of the substrate that can be used include paper,
Coated papers, nonwovens, plastic films and synthetic papers are included.

Examples of the polymer constituting the plastic film and the synthetic paper include polyolefins such as polyethylene and polypropylene, ethylene-vinyl acetate copolymer, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, and poly (meth) acrylic. Acid esters, polystyrene, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, cellulose derivatives such as cellulose acetate,
Polyester (polyalkylene terephthalate such as polyethylene terephthalate and polybutylene terephthalate, polyalkylene naphthalate such as polyethylene naphthalate and polybutylene naphthalate, etc.), polycarbonate, polyamide (polyamide 6, polyamide 6)
/ 6, polyamide 6/10, polyamide 6/12, etc.), polyesteramide, polyether, polyimide, polyimideamide, polyetherester, and the like. Is also good.

As the polymer constituting these films or synthetic papers, polyolefins (especially polypropylene), polyesters (especially polyethylene terephthalate, etc.), polyamides and the like are usually used, and particularly, such as mechanical strength, workability and cost. From the viewpoint, polyester (particularly, polyethylene terephthalate) is preferred. As the paper or coated paper, for example, high quality paper, art paper, RC paper and the like can be used.

The thickness of the substrate can be selected according to the application, and is usually from 5 to 500 μm, preferably from about 10 to 300 μm. The base material has a sizing agent, an antioxidant, an ultraviolet absorber, a heat stabilizer,
Conventional additives such as lubricants and pigments may be used.

In order to improve the adhesion to the ink receiving layer, a surface treatment such as a corona discharge treatment or an undercoat treatment may be performed.

5. Method for Producing Recording Sheet The recording sheet of the present invention can be produced by forming an ink receiving layer on at least one surface of the above-mentioned base material with a coating liquid comprising the resin composition for inkjet recording of the present invention. That is, the ink receiving layer can be formed by applying the prepared coating liquid to the substrate. The coating solution is formed 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, a silk screen coater method, or the like. Is cast or applied. The ink receiving layer can be formed by applying a coating liquid containing the above components to at least one surface of the base material and drying. Further, if necessary, after the coating liquid is applied, a crosslinked ink absorbing layer may be formed by heating at an appropriate temperature selected from the range of about 50 to 150 ° C. In addition, a porous layer, an anti-blocking layer, a lubricating layer, an antistatic layer, and the like may be formed on the ink receiving layer, if necessary. Further, if necessary, the surface of the ink receiving layer such as a super calender may be subjected to a smoothing treatment.

The thickness of the ink receiving layer formed of the resin composition for inkjet recording containing the binder resin (A), the inorganic fine particles (B) and the aqueous solvent (C) can be selected according to the intended use. 3 to 50 μm, preferably about 6 to 30 μm, usually 5 to 30 μm
It is about.

[0065]

The present invention will be described below in more detail with reference to Examples, but the present invention is not limited to these Examples. Unless otherwise specified, the parts by weight of the acrylic copolymer (c) and the inorganic fine particles (B) are:
Convert to solid content.

The coating solutions obtained in Examples and Comparative Examples were evaluated as follows. (Mechanical stability) 15 or 2 using Marlon testing machine
A load of 5 kgf is applied and 1000 r. p. The degree of precipitation when stirring at 15 m for 15 minutes was visually determined. A: No solidified product was precipitated when a load of 25 kgf was applied. ：: No solidified product was precipitated when a load of 15 kgf was applied. ×: A solidified substance is precipitated when a load of 15 kgf is applied.

Synthesis Example 1 Synthesis of Hydrolyzable Silyl Group-Containing Anionic Acrylic Copolymer (c-1) A 2 liter reaction vessel equipped with a stirrer, a reflux condenser, a dropping funnel, a nitrogen inlet tube and a thermometer. , 175 parts by weight of isopropyl alcohol (hereinafter abbreviated as "IPA") and azobisisobutyronitrile (hereinafter referred to as "AIB") while stirring.
N ”. ) Add 0.62 parts by weight and dissolve,
Was heated. As copolymerization components, 96 parts by weight of methyl methacrylate (hereinafter abbreviated as “MMA”), 62 parts by weight of n-butyl acrylate (hereinafter abbreviated as “BA”), 3-
6 parts by weight of methacryloxypropyltrimethoxysilane (manufactured by Nippon Unicar Co., Ltd., A-174) and 6 parts by weight of acrylic acid (hereinafter abbreviated as "AA") are mixed, and the mixture is taken using a dropping funnel for about 4 hours. It was dropped into the reaction vessel. After dropping, 0.25 parts by weight of AIBN was added as an additional catalyst to IPA2.
It was dissolved in 5 parts by weight, added dropwise to the reaction vessel, and the reaction was maintained for another 2 hours. After the polymerization is completed, stirring is continued for 25 minutes.
% Aqueous ammonia was added to the reaction vessel, and 70 parts of water was added.
5 parts by weight was dropped into the reaction vessel over about 2 hours to emulsify. After emulsification, the IPA was evaporated using a rotary evaporator to obtain the desired hydrolyzable silyl group-containing anionic acrylic copolymer (c-1). The solid content of this resin composition was 40% by weight.

Synthesis Example 2 Synthesis of Hydrolyzable Silyl Group-Containing Cationic Acrylic Copolymer (c-2) A 2 liter reaction vessel equipped with a stirrer, reflux condenser, dropping funnel, nitrogen inlet tube and thermometer was used. , IPA (219 parts by weight) was added, and AIBN (1.23 parts by weight) was added thereto with stirring to dissolve the mixture, followed by heating to 80 ° C. MMA9 as a copolymer component
3.7 parts by weight, BA 98.7 parts by weight, 3-methacryloxypropyltrimethoxysilane (Nihon Unicar Co., Ltd.)
(A-174), 4.93 parts by weight of diethylaminoethyl methacrylate, and 49.3 parts by weight of the mixture were added dropwise to the reaction vessel over about 4 hours using a dropping funnel. After dropping, 0.25 parts by weight of AIBN was added as an additional catalyst to IPA2.
It was dissolved in 5 parts by weight, added dropwise to the reaction vessel, and the reaction was maintained for another 2 hours. After completion of the polymerization, 16 parts by weight of acetic acid was added to the reaction vessel while stirring was continued, and 705 parts by weight of water was added dropwise to the reaction vessel over about 2 hours to emulsify. After the emulsification, IP was obtained using a rotary evaporator.
A was evaporated to obtain a hydrolyzable silyl group-containing cationic acrylic copolymer (c-2). The solid content of this resin composition was 40% by weight.

Synthesis Example 3 Synthesis of Hydrolyzable Silyl Group-Containing Anionic Acrylic Copolymer (c-3) One of water added for emulsification after completion of polymerization.
70 parts by weight (wet weight) of colloidal silica dispersed in water (manufactured by Nissan Chemical Industries, Ltd., ST-20, solid content 20)
%), Except that the polymerization reaction and emulsification were carried out in the same manner as (c-1), except that the desired hydrolyzable silyl group-containing anionic acrylic copolymer (c-3) was obtained. The solid content of this resin composition was 40% by weight.

Synthesis Example 4 Synthesis of Hydrolyzable Silyl Group-Containing Anionic Acrylic Copolymer (c-4) 175 parts by weight of IPA used as a polymerization solvent was mixed with IPA9.
6 parts by weight and 113 parts by weight (wet weight) of colloidal silica dispersed in IPA (manufactured by Nissan Chemical Industries, Ltd., IPA-ST, solid content 30%, hereinafter abbreviated as “IPA-ST”) A polymerization reaction and emulsification were carried out in the same manner as (c-1) except for the above, to obtain a target hydrolyzable silyl group-containing anionic acrylic copolymer (c-4). The solid content of this resin composition was 40% by weight.

Synthesis Example 5 Synthesis of Anionic Acrylic Copolymer (c-5) The polymerization reaction and emulsification were carried out in the same manner as in (c-1) except that 3-methacryloxypropyltrimethoxysilane was not used. Then, the desired acrylic copolymer (c
-5) was obtained. The solid content of this resin composition was 40% by weight.

Synthesis Example 6 Synthesis of Hydrolyzable Silyl Group-Containing Anionic Acrylic Copolymer (c-6) A 2 liter reaction vessel equipped with a stirrer, reflux condenser, dropping funnel, nitrogen inlet tube, and thermometer. Then, 318 parts by weight of ion-exchanged water was added, stirred, and heated to 75 ° C. 73 parts by weight of MMA, 24 parts by weight of BA, 3-methacryloxypropyltrimethoxysilane (manufactured by Nippon Unicar Co., Ltd., A-17
4) An emulsion obtained by emulsifying 0.7 parts by weight, 5 parts by weight of a surfactant (Newcol 707SF, manufactured by Nippon Emulsifier Co., Ltd.) and 60 g of ion-exchanged water, and a catalyst aqueous solution (0.5 g of potassium persulfate and (16.5 g of an aqueous solution of ion-exchanged water) was dropped into the reaction vessel over 2 hours. One more
After reacting for an hour, the mixture was cooled to room temperature to obtain the desired aqueous emulsion of the hydrolyzable silyl group-containing anionic acrylic copolymer (c-6). The solid content of this resin composition was 40% by weight.

[Synthesis Example 7] Synthesis of anionic acrylic copolymer (c-7) A polymerization reaction was carried out in the same manner as in (c-6) except that 3-methacryloxypropyltrimethoxysilane was not used. Aqueous emulsion of anionic acrylic copolymer (c-7) was obtained. The solid content of this resin composition is 40
% By weight.

Example 1 Spherical colloidal silica (manufactured by Nissan Chemical Co., Ltd., ST-) was added to 100 parts by weight of a hydrolyzable silyl group-containing anionic acrylic copolymer (c-1).
(50, solid content: 50%) 400 parts by weight, and ion-exchanged water was added so that the solid content concentration of the coating solution was 40% by weight to obtain a coating solution 1. The coating liquid 1 is composed of 20% by weight of the acrylic copolymer (c-1), 80% by weight of spherical colloidal silica, and 150 parts by weight of ion-exchanged water with respect to 100 parts by weight of the solid component.

Example 2 Cationic colloidal silica (manufactured by Nissan Chemical Co., Ltd.) was used with respect to 100 parts by weight of a hydrolyzable silyl group-containing cationic acrylic copolymer (c-2).
(Snowtex AK, solid content 19%) was mixed with 400 parts by weight, and ion-exchanged water was added so that the solid content concentration of the coating solution was 20% by weight to obtain a coating solution 2. The coating liquid 2 is composed of 20% by weight of the acrylic copolymer (c-2), 80% by weight of the cationic colloidal silica, and 400 parts by weight of ion-exchanged water with respect to 100 parts by weight of the solid component.

Example 3 Spherical colloidal silica (manufactured by Nissan Chemical Industries, Ltd., ST-120) was added to 120 parts by weight of a hydrolyzable silyl group-containing cationic acrylic copolymer (c-3).
380 parts by weight (50, solid content: 50%) was added, and ion-exchanged water was added so that the solid content concentration of the coating solution was 40% by weight, to obtain a coating solution 3. The coating liquid 3 is composed of 20% by weight of the acrylic copolymer (c-3), 80% by weight of spherical colloidal silica, and 150 parts by weight of ion-exchanged water with respect to 100 parts by weight of the solid component.

Example 4 Spherical colloidal silica (manufactured by Nissan Chemical Industries, Ltd., ST-120) was added to 120 parts by weight of a hydrolyzable silyl group-containing cationic acrylic copolymer (c-4).
380 parts by weight (50, solid content: 50%) were mixed, and ion-exchanged water was added so that the solid content concentration of the coating solution was 40% by weight to obtain a coating solution 4. The coating liquid 4 is composed of 20% by weight of the acrylic copolymer (c-4), 80% by weight of spherical colloidal silica, and 150 parts by weight of ion-exchanged water with respect to 100 parts by weight of the solid component.

Example 5 Spherical colloidal silica (manufactured by Nissan Chemical Co., Ltd., ST-) was added to 100 parts by weight of an anionic acrylic copolymer containing a hydrolyzable silyl group (c-6).
(50, solid content: 50%), 400 parts by weight, and ion-exchanged water was added so that the solid content concentration of the coating solution was 40% by weight to obtain a coating solution 5. The coating liquid 5 is composed of 20% by weight of the acrylic copolymer (c-6), 80% by weight of spherical colloidal silica, and 150 parts by weight of ion-exchanged water with respect to 100 parts by weight of the solid component.

Comparative Example 1 A spherical colloidal silica (manufactured by Nissan Chemical Industries, Ltd., ST-50, solid content 50%) was added to 100 parts by weight of the anionic acrylic copolymer (c-5).
00 parts by weight, and the solid content concentration of the coating solution is 40% by weight.
Ion-exchanged water was added to obtain coating solution 6. The coating liquid 6 was composed of 20% by weight of an acrylic copolymer (c-5), 80% by weight of spherical colloidal silica,
It consists of 150 parts by weight of ion exchange water with respect to 0 parts by weight.

Comparative Example 2 Spherical colloidal silica (manufactured by Nissan Chemical Co., Ltd., ST-50, solid content 50%) was added to 100 parts by weight of anionic acrylic copolymer (c-7).
00 parts by weight, and the solid content concentration of the coating solution is 40% by weight.
Ion-exchanged water was added to obtain coating solution 7. The coating liquid 7 was composed of 20% by weight of an acrylic copolymer (c-7), 80% by weight of spherical colloidal silica,
It consists of 150 parts by weight of ion exchange water with respect to 0 parts by weight.

The coating solution of the example was applied to a 190 μm thick art paper (NK Whitening loss 180.0) to form an ink receiving layer having a dry thickness of 45 μm, and printed with an Epson printer (Epson PM770C). An accurate full-color image was obtained. Table 1 shows the evaluation results of the coating solutions of the examples and the comparative examples.

[0082]

[Table 1]

[0083]

According to the present invention, a resin composition in which a hydrolyzable silyl group-containing acrylic copolymer, inorganic fine particles and an aqueous solvent are mixed at a specific ratio is used for a coating liquid for forming an ink receiving layer of an ink jet recording sheet. Thereby, the mechanical stability of the coating liquid is improved.

Claims (7)

[Claims] 1. A recording resin composition containing a binder resin (A), inorganic fine particles (B) and an aqueous solvent (C), wherein the binder resin (A) is a polymerizable unsaturated compound having a hydrolyzable silyl group. 0.5 to 15% by weight of a monomer (a) and 99.5 to 99.5% of another polymerizable unsaturated monomer (b)
Acrylic copolymer (c) obtained by copolymerizing 85% by weight with an aqueous solvent (C) containing 3 to 60% by weight of binder resin (A) and 97 to 40% of inorganic fine particles (B).
100% by weight of the solid component consisting of 100% by weight.
A resin composition for ink-jet recording, characterized in that it is contained in a proportion of up to 2000 parts by weight. 2. The acrylic copolymer (c) is an aqueous resin composition obtained by adding water to a resin solution obtained by solution polymerization, emulsifying the resin solution, and then removing the polymerization solvent. The ink-jet recording resin composition according to claim 1. 3. A second solution, which is an aqueous solution containing inorganic fine particles (B), is added to a first solution, which is a resin solution of the acrylic copolymer (c) obtained by solution polymerization, to form an emulsion. The resin composition for inkjet recording according to claim 1, wherein the resin composition is an aqueous resin composition obtained by removing a polymerization solvent contained in the first solution. 4. An acrylic copolymer (c) is prepared by mixing a polymerizable unsaturated monomer (a) having a hydrolyzable silyl group with another polymerizable unsaturated monomer in the presence of inorganic fine particles (B). The resin composition for inkjet recording according to claim 1, which is a resin composition obtained by copolymerizing the compound (b). 5. The resin composition for ink jet recording according to claim 1, wherein a mechanical stability test according to JIS K 6392 is stable under a load of 15 kgf. 6. The ink-jet recording resin composition according to claim 1, wherein the inorganic fine particles (B) are colloidal silica. 7. A recording sheet comprising, on a base material, an ink receiving layer formed of the resin composition for ink jet recording according to claim 1.