JP2005001377A - Ink-jet recording paper sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink-jet recording paper sheet which is excellent in the ink-jet recording aptitude such as a gloss in the area of blank and print, print density, ink absorbency, recording quality of image and conveyance performance. <P>SOLUTION: The ink-jet recording paper sheet consisting of a substrate and at least one of coating layers formed on the substrate employs (A) an anion colloidal silica treated with a coupling agent and (B) a layer containing a polymer, at least in the surface layer of the coating layers. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ink jet recording paper, and more particularly to an ink jet recording paper excellent in glossiness and ink jet recording suitability of a white paper portion and a printing portion.

Inkjet printer recording has been used in many fields in recent years because it has low noise, enables high-speed recording, and can easily be multicolored.
As ink jet recording paper used for such ink jet printer recording, high-quality paper devised to be rich in ink absorbability, coated paper coated with a porous pigment on the surface, and the like are generally used. .
By the way, all of these papers are mainly of a so-called matte tone having a low surface glossiness, but with the recent advancement of printer technology, high-quality recording comparable to silver halide photography has become possible. Therefore, there is an increasing demand for ink jet recording paper having a high surface glossiness and an excellent appearance.

In general, as a paper having a high surface glossiness, a coated drum having a high gloss with a plate-like pigment applied to the surface and further subjected to a calendar treatment as necessary, or a heating drum having a mirror surface with a wet coating layer A so-called cast coated paper is known which is obtained by transferring a mirror surface by pressure bonding to a surface and drying.
This cast-coated paper has high surface gloss and superior surface smoothness compared to normal coated paper with a super calender finish, and provides excellent printing effects. Used exclusively for usage.

In Patent Document 1 (Japanese Patent Laid-Open No. 5-59688) and Patent Document 2 (Japanese Patent Laid-Open No. 5-78995), a coating layer mainly composed of a pigment and an adhesive is provided on a base paper, and the coating layer is provided. A polymer obtained by polymerizing a monomer having an ethylenically unsaturated bond, and a production method for obtaining cast paper by applying a rewetting liquid containing colloidal silica having an average particle size of 5 to 100 nm and a release agent Has been.
In this case, the film-forming substance such as an adhesive in the coating layer has a high gloss by copying the mirror drum surface of the cast coater. However, the presence of this film-forming substance causes the coating layer to be porous. And the problem is that the absorption of ink during ink jet recording is extremely reduced.

In order to solve this problem and improve the ink absorbability of the recording paper, it is important to make the coating layer porous so that the ink can be easily absorbed. Therefore, it is necessary to reduce the film formability. Become. However, when the amount of the film-forming substance is reduced, another problem arises that the glossiness of the recording paper is lowered.
As described above, it was extremely difficult to satisfy both the surface gloss of cast coated paper and the ink jet recording suitability at the same time.

  In Patent Document 3 (Japanese Patent Laid-Open No. 7-89220), 40 ° C. or higher obtained by polymerizing a monomer having an ethylenically unsaturated bond on a base paper provided with a recording layer mainly composed of a pigment and an adhesive. A cast coating layer is formed by applying a coating liquid mainly composed of a copolymer having a glass transition point, and is pressed against a heated mirror drum while the cast coating layer is wet and dried. It is described that, when finished, an ink-jet recording cast paper having both excellent gloss and ink absorbability can be obtained.

  However, in recent years, with the expansion of applications such as high speed inkjet recording, high definition of recorded images, and full color, there has been a demand for higher gloss, high image quality, and higher recording density. However, the cast paper of Patent Document 3 does not sufficiently satisfy such requirements. On the other hand, dye-based inks have been mainly used as inks for printing with full-color inks, but pigment-based inks have recently been used. Therefore, a recording medium capable of giving a high-resolution recording image to both of these inks is desired.

Patent Document 4 (Japanese Patent Application Laid-Open No. 2000-238418) discloses an ink jet recording comprising a polymer emulsion having an average particle size of 0.02 to 0.15 μm and colloidal silica having an average particle size of 0.01 to 0.15 μm. A surface coating agent for paper is described.
In Patent Document 5 (Japanese Patent Laid-Open No. 2000-238419), a polymer emulsion having an average particle diameter of 0.02 to 0.15 μm and colloidal silica having an average particle diameter of 0.01 to 0.15 μm are coated on the surface layer. To form a cast coating layer, and immediately press and dry the coated coating layer on a heated mirror drum, so that the glossiness, print density, ink absorbency, It is described that a cast paper for ink jet recording excellent in recording image quality and the like can be obtained.
In these methods, although ink jet recording paper having gloss and recording image quality superior to those of the conventional methods can be obtained, further improvements in recording image quality and the like have been demanded with the technical progress of the ink jet printer described above. is there.

JP-A-5-59688 (2nd page) Japanese Patent Laid-Open No. 5-78995 (page 2) JP-A-7-89220 (2nd page) JP 2000-238418 A (2nd, 5th, 6th pages) JP 2000-238419 A (No. 2, pages 9 to 11)

  The present invention has been made in view of the above circumstances, and provides an ink jet recording paper excellent in ink jet recording suitability such as glossiness, print density, ink absorbability, recording image quality, and transportability of a blank paper portion and a print portion. Objective. Furthermore, it aims at providing the inkjet recording paper excellent in the inkjet suitability of both dye-type ink and pigment-type ink.

  As a result of intensive studies to achieve the above object, the present inventors have made a base material comprising a layer containing an anionic colloidal silica treated with a coupling agent, preferably a silane coupling agent, and a polymer emulsion. The ink jet recording paper formed above has excellent transportability in the recording device, excellent glossiness of the blank paper portion and the print portion, and excellent print density, ink absorbability, recording image quality, etc., and uses dye-based ink. The present invention has been completed by finding that it is suitable for both printing using conventional inks and printing using pigment-based inks.

（式中、Ｒ¹は水素原子またはメチル基を示し、Ｒ²は炭素数１〜２２の飽和もしくは不飽和の直鎖状または分岐状の脂肪族炭化水素基を示す。）
（ｃ）α，β−不飽和カルボン酸およびその塩類から選ばれる少なくとも１種のモノマー：０．５〜３０質量％
（ｄ）（ａ）〜（ｃ）のモノマーと共重合可能なモノマー：０〜２０質量％
７． 前記表層が、キャスト方式で形成されたことを特徴とする１〜６のいずれかのインクジェット記録用紙、
８． ＪＩＳ−Ｚ−８７４１に準拠した方法により測定した表面の７５°光沢度が、３０％以上であることを特徴とする１〜７のいずれかのインクジェット記録用紙
を提供する。 That is, the present invention
1. An anion recording paper comprising a substrate and at least one coating layer formed on the substrate, wherein at least a surface layer of the coating layer is treated with (A) a coupling agent. An ink jet recording paper comprising: a colloidal silica and (B) a polymer;
2. An inkjet recording paper having a base material, a base material, and a surface layer formed on the base material, wherein the surface layer comprises (A) an anionic colloidal silica treated with a coupling agent, and (B) a weight An ink jet recording paper comprising:
3. The (B) polymer is coated on the substrate as a polymer emulsion, and the average particle size of the polymer emulsion is 0.02 to 0.15 μm. Recording sheet,
4). The inkjet recording paper according to any one of 1 to 3, wherein the coupling agent is a silane coupling agent,
5. The ink jet recording paper according to any one of 1 to 4, wherein the surface layer further comprises (C) anionic colloidal silica;
6). The (B) polymer is a copolymer obtained by copolymerizing the following monomers (a) to (d) at the ratio shown below, and the glass transition temperature of this copolymer is 0 to 200 ° C. Any one of the ink jet recording papers 1 to 5,
(A) At least one monomer selected from styrene and α-methylstyrene: 5 to 95% by mass
(B) At least one monomer selected from acrylic acid ester and methacrylic acid ester represented by the following general formula (1): 0.5 to 94.5% by mass

(Wherein, R ¹ represents a hydrogen atom or a methyl group, R ² represents a linear or branched aliphatic saturated or unsaturated hydrocarbon group having 1 to 22 carbon atoms.)
(C) At least one monomer selected from α, β-unsaturated carboxylic acid and salts thereof: 0.5 to 30% by mass
(D) Monomer copolymerizable with monomers (a) to (c): 0 to 20% by mass
7. The ink jet recording paper according to any one of 1 to 6, wherein the surface layer is formed by a cast method,
8). The inkjet recording paper according to any one of 1 to 7, wherein the surface has a 75 ° glossiness of 30% or more measured by a method according to JIS-Z-8741.

The ink jet recording paper of the present invention has a layer containing an anionic colloidal silica treated with a coupling agent and a polymer at least on the surface layer, and in particular, gloss, print density, and ink absorption of a blank paper portion and a print portion. Excellent in ink jet recording suitability such as recording property, recording image quality, and transportability.
Further, it is possible to provide an ink jet recording paper having excellent ink jet recording suitability not only for dye-based inks but also for pigment-based inks.

Hereinafter, the present invention will be described in more detail.
As described above, the ink jet recording paper according to the present invention has a plurality of coating layers having at least a surface layer containing (A) an anionic colloidal silica treated with a coupling agent and (B) a polymer. It is provided on a base material or a surface layer containing (A) an anionic colloidal silica treated with a coupling agent and (B) a polymer directly on the base material.
Here, the anionic colloidal silica treated with the coupling agent is a colloidal solution in which spherical silica is dispersed in water, and the silanol groups on the particle surface are negatively charged. Sodium hydroxide, sodium silicate, organic It exhibits anionicity by neutralization with a base such as an amine.

As such anionic colloidal silica, commercially available products can be used. For example, silica dol (manufactured by Nippon Chemical Industry Co., Ltd.), Adelite AT (manufactured by Asahi Denka Kogyo Co., Ltd.), cataloid ( Catalytic Chemical Industry Co., Ltd.), Snowtex (Nissan Chemical Industry Co., Ltd.), etc., but a sol-like aqueous dispersion having a pH of 8-12 and a weight concentration of 20-50% It is preferable from the viewpoint of compatibility stability with the combined emulsion.
The average particle diameter of the anionic colloidal silica is not particularly limited, but is preferably 0.01 to 0.15 μm, more preferably 0.02 to 0.12 μm. If the average particle size is less than 0.01 μm, the ink absorbability may be lowered, and if it exceeds 0.15 μm, the sharpness of the recorded image may be lowered.

The coupling agent used for the treatment of anionic colloidal silica is not particularly limited, and various known coupling agents can be used, but from the viewpoint of excellent reactivity with colloidal silica, It is preferable to use a silane coupling agent.
Examples of the silane coupling agent include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropylmethyldichlorosilane, γ-chloropropylmethyldimethoxysilane, γ- Chloropropylmethyldiethoxysilane, γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ -Mercaptopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysila Can be used. These may be used alone or in combination of two or more.

In the present invention, the anionic colloidal silica treated with the coupling agent can be usually obtained by adding a coupling agent to the anionic colloidal silica.
Specific treatment methods include, for example, a method in which anionic colloidal silica is preferably heated to 40 to 95 ° C., particularly about 70 ° C., and a coupling agent is continuously added dropwise thereto, and an anionic colloidal silica and a coupling agent are added. After charging and mixing at room temperature, reacting by heating to the above temperature, dropping the coupling agent to the anionic colloidal silica under reduced pressure, dropping the coupling agent and the alkali catalyst simultaneously onto the anionic colloidal silica Method, a method in which a coupling agent and an acid catalyst are simultaneously dropped onto an anionic colloidal silica, a method in which a coupling agent is dissolved in a solvent, and a reaction system containing an anionic colloidal silica, a coupling agent by an emulsifier A method of supplying to a reaction system containing anionic colloidal silica in an emulsified state, etc. Among them, it is possible to use a method in which anionic colloidal silica is heated to drop a coupling agent, or a method in which anionic colloidal silica and a coupling agent are charged at room temperature, mixed and then heated to react. preferable.

When the anionic colloidal silica is treated with the silane coupling agent, the amount of the silane coupling agent used is, for example, the addition amount of the silane coupling agent is usually 0 with respect to the effective amount of SiO _{2 in} the colloidal silica. 0.01 to 20% by mass, preferably 0.02 to 10% by mass, more preferably 0.05 to 5.0% by mass. If the amount added is less than 0.01% by mass, a sufficient effect of improving the dispersion stability cannot be obtained, and at the same time, the suitability of the pigment ink may be insufficient, and if it exceeds 20% by mass, the dispersion stability may be lowered. is there.

  The polymer (B) contained in at least the surface layer of the inkjet recording paper of the present invention is not particularly limited, and various adhesives commonly used in the field of coated paper can be used. Polymers (polyvinyl alcohols containing modified polyvinyl alcohol such as polyvinyl alcohol, cation-modified polyvinyl alcohol, silyl-modified polyvinyl alcohol, casein, soy protein, synthetic proteins, starch and modified products thereof, gelatin and modified products thereof, pullulan, arabian Natural polymer resins such as rubber, karaya gum, albumin or derivatives thereof, cellulose derivatives such as carboxymethylcellulose, methylcellulose, methylhydroxyethylcellulose, methylhydroxypropylcellulose, hydroxyethylcellulose ); Conjugated diene polymers such as (meth) acrylic acid ester polymers or copolymers, ethylene-vinyl acetate copolymers, styrene-butadiene copolymers, methyl methacrylate-butadiene copolymers, Water-dispersible resins such as vinyl copolymers such as ethylene-vinyl acetate copolymer; water-based acrylic resin, water-based polyurethane resin, water-based polyester resin, SBR latex, NBR latex and the like. These may be used alone or in combination of two or more.

As the polymer (B) in the present invention, various polymers can be used as described above. In particular, a copolymer obtained by copolymerizing the monomers (a) to (d) in the above ratio is used. preferable.
In this case, specific types and copolymerization ratios of the monomers (a) to (d) are determined in consideration of the performance of the resulting composition and ink jet recording paper.
The monomer (a) is at least one monomer selected from styrene and α-methylstyrene, and the copolymerization ratio thereof is preferably 5 to 95% by mass, more preferably 30 to 90% by mass. If it is less than 5% by mass, the print gloss may be insufficient, and if it exceeds 95% by mass, the light resistance may be insufficient.
In addition, when using this copolymer and the other polymer illustrated above together, the compounding quantity of another polymer consists of anionic colloidal silica (A) and the monomer of (a)-(d). It is 0.1-50 mass% normally with respect to the total amount with a copolymer, Preferably it is 1-30 mass%.

The monomer (b) is at least one monomer selected from the acrylic ester and methacrylic ester represented by the above formula (1), and the copolymerization ratio is preferably 0.5 to 94.5 mass. %, More preferably 1 to 85% by mass. If the amount is less than 0.5% by mass, the sharpness of the color of the recorded image may be lowered. If the amount exceeds 94.5% by mass, the resolution of the recorded image may be lowered.
In the formula (1), examples of the saturated or unsaturated linear or branched aliphatic hydrocarbon group having 1 to 22 carbon atoms include methyl, ethyl, n-butyl, s-butyl, t-butyl, A pentyl, 2-ethylhexyl, lauryl, a stearyl group etc. are mentioned.

  Specific examples of the monomer (b) include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, and lauryl acrylate. Lauryl methacrylate, stearyl acrylate, stearyl methacrylate and the like. These may be used alone or in combination of two or more. In particular, it is particularly preferable to use an acrylate ester for the purpose of improving the transportability in the recording apparatus and the resolution of the recorded image in a well-balanced manner.

The monomer (c) is at least one monomer selected from α, β-unsaturated carboxylic acids and salts thereof, and the copolymerization ratio is preferably 0.5 to 30% by mass, more preferably, 1 to 20% by mass. If it is less than 0.5% by mass, the resolution of the recorded image may be lowered, and if it exceeds 30% by mass, the water resistance may be lowered.
Specific examples of the monomer (c) include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, and their sodium, potassium and ammonium salts. These may be used alone or in combination of two or more. In particular, sodium salt or ammonium salt of acrylic acid or methacrylic acid is preferred because of cost and adhesion strength to the substrate.

The monomer (d) is an arbitrary monomer that can be copolymerized with the monomers (a) to (c) and is used in a range that does not inhibit the effect of the coating layer, and the copolymerization ratio thereof is 20 mass. % Or less, preferably 0.1 to 15% by mass. If it exceeds 20% by mass, the print gloss may be lowered.
Specific examples of the monomer (d) include, for example, acrylamide, methacrylamide, N-hydroxymethyl acrylamide, 2-hydroxyethyl acrylate, methoxypolyethylene glycol methacrylate, vinyl acetate, acrylonitrile, methylene bisacrylamide, polyethylene glycol diacrylate, Examples thereof include divinylbenzene, trimethylolpropane triacrylate, styrenesulfonic acid and its salts, 2-acrylamido-2-methylpropanesulfonic acid and its salts.

  Although the glass transition temperature Tg of the polymer in this invention is not restrict | limited in particular, Preferably it is 0-200 degreeC, More preferably, it is 20-180 degreeC. When the glass transition temperature is less than 0 ° C, the thermal stability of the coating layer (coating film) is insufficient, and there is a risk of causing problems such as fusion when the coated surfaces are overlaid. There is a possibility that a coating layer (coating film) cannot be formed.

In the present invention, the glass transition temperature Tg of the polymer is a value calculated from the following Fox (FOX) equation.
In the following formula 1, Tg _{a to} Tg _d represent the glass transition temperature (K) of the homopolymer of each monomer of the above (a) to (d), and a to d represent the above (a) to (d). The copolymerization mass ratio of each monomer is shown, and a + b + c + d = 1.

The polymerization method and polymerization conditions for obtaining the polymer (B) are not particularly limited. For example, a usual emulsion polymerization method or the like can be used. In particular, the solid content of the polymer emulsion is 20 to 50 mass. %, And the average particle diameter is preferably 0.02 to 0.15 μm, particularly preferably 0.03 to 0.10 μm.
Here, if the average particle size is less than 0.02 μm, the print gloss may be lowered, whereas if it exceeds 0.15 μm, the sharpness of the recorded image may be lowered.

  Specifically, an emulsifier or the like is dissolved in water and, for example, the copolymer components (a), (b), (c), and (d) are added to emulsify, and a radical polymerization initiator is added to simultaneously react. In addition to the method of carrying out emulsion polymerization, there are methods of supplying the above-mentioned copolymerization component or radical polymerization initiator to the reaction system by methods such as continuous dropping and split charging, among these, the aggregate The continuous dripping method is preferred from the viewpoint that it is difficult to generate byproducts. In each of the above methods, a method of supplying the monomer composition to the reaction system in an emulsified state with an emulsifier can also be used. The polymerization temperature is preferably 40 to 95 ° C. In addition, in the emulsion polymerization method by continuous dripping, the method described in Japanese Patent Application No. 2002-146460 can be used in which the copolymer component is divided and polymerized in two stages.

In the case of employing emulsion polymerization, various conventionally known emulsifiers can be used as the emulsifier, but an anionic emulsifier is preferably used from the viewpoint of efficiently controlling the average particle size of the copolymer emulsion. preferable. Examples of such anionic emulsifiers include higher alcohol sulfates, alkylbenzene sulfonates, aliphatic sulfonates, dialkyl sulfosuccinates, alkyl naphthalene sulfonates, alkyl diphenyl ether disulfonates, and polyoxyethylene alkyl ethers. Emulsifiers such as sulfate ester salt, polyoxyethylene alkylphenyl ether sulfate ester, allyl alkylphenyl polyethylene oxide sulfate ester salt, and allyl alkyl sulfosuccinic acid diester salt can be used.
In addition, nonionic emulsifiers such as polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, and polymer emulsifiers such as sodium polystyrene sulfonate and sulfonated polyvinyl alcohol are used in combination with anionic emulsifiers. There is no problem.

  On the other hand, the radical polymerization initiator used in the emulsion polymerization is not particularly limited, and examples thereof include peroxides such as hydrogen peroxide, ammonium persulfate, sodium persulfate, and potassium persulfate, and those peroxides. Various redox initiators usually used in combination, and azo initiators such as 2,2-azobis (aminodipropane) hydrochloride can be used. Further, if necessary, a molecular weight modifier such as dodecyl mercaptan, dialkylamine, or allyl alcohol may be used.

  In the present invention, the composition ratio between the anionic colloidal silica (A) treated with the coupling agent and the polymer (emulsion) (B) is preferably 9.7 / 0.3 to 4/6 in terms of solid content, More preferably, it is 9.5 / 0.5-5 / 5, More preferably, it is the range of 9.3 / 0.7-6 / 4. If the ratio of the polymer (emulsion) exceeds 60% by mass, the sharpness of the recorded image may be reduced, and if it is less than 3% by mass, the glossiness may decrease.

When the polymer (B) is used in the form of an emulsion, the ratio (X) / (Y) of the average particle size (X) of the anionic colloidal silica and the average particle size (Y) of the polymer emulsion is , Preferably 0.2 to 2.0, more preferably 0.3 to 1.5. If (X) / (Y) is outside the range of 0.2 to 2.0, the sharpness and glossiness of the recorded image may be reduced.
In the present invention, each average particle diameter refers to a value measured by an electrophoretic light scattering photometer (ELS-800, manufactured by Otsuka Electronics Co., Ltd.).

  In the ink jet recording paper of the present invention, the coating layer containing the components (A) and (B) can further contain (C) anionic colloidal silica that is not subjected to a coupling treatment. In this case, the addition amount is preferably 500 parts by mass or less with respect to 100 parts by mass of the anionic colloidal silica treated with the coupling agent. Beyond this, there is a high possibility that the dispersion stability is particularly impaired.

  In the inkjet recording paper of the present invention, at least the surface layer in the plurality of coating layers formed on the base material, or the surface layer directly formed on the base material is, as described above, (A) a coupling agent. It contains treated anionic colloidal silica and (B) copolymer. The blending ratio of these components is not particularly limited, but is usually 10 to 100% by mass, preferably 30 to 100% by mass, based on the total mass of the layer containing these components.

Moreover, in addition to the anionic colloidal silica processed with the said (A) coupling agent, another pigment can also be mix | blended with each said surface layer. As the kind of pigment, colloidal silica, amorphous silica, aluminum oxide, zeolite, synthetic smectite and the like other than those described above are preferable from the viewpoint of enhancing gloss, transparency, and ink absorbability. The average particle diameter of these pigments is preferably from 0.01 to 5 μm, more preferably from 0.05 to 1 μm. When the average particle diameter is less than 0.01 μm, the ink absorbability may not always be sufficient, and when it exceeds 5 μm, there is a possibility that gloss and a decrease in print density may occur.
Particularly, when silica fine particles having an average primary particle diameter of 3 to 40 nm and an secondary particle average particle diameter of 10 to 300 nm are used as amorphous silica, the gloss and ink absorbability are extremely excellent. It becomes.
In addition, it is preferable that the anionic colloidal silica and the polymer (emulsion) treated with each of the pigments and the coupling agent have the same ionicity from the viewpoint of improving the mixing property.

  Further, in the coating liquid when forming the coating layer such as the surface layer of the present invention, it is used for general printing coating liquid and inkjet paper in order to adjust the whiteness, viscosity, fluidity, etc. Various auxiliary agents such as pigments, antifoaming agents, colorants, fluorescent brighteners, antistatic agents, preservatives and dispersants, thickeners, and the like can be appropriately added. It is also possible to add ink dye fixing properties by blending a cationic resin.

  In the formation of each surface layer, a cast method or a film transfer method using a heated mirror surface, which will be described later, can be adopted. In such an aspect, for the purpose of imparting releasability from a cast drum or a film. A mold release agent can be added. As the release agent, a release agent used in the production of ordinary printing coated paper or printing cast paper can be used. Specifically, polyolefin waxes such as polyethylene wax and polypropylene wax, higher fatty acid alkali salts such as calcium stearate, zinc stearate, potassium oleate and ammonium oleate, silicone compounds such as silicone oil and silicone wax, polytetrafluoro Fluorine compounds such as ethylene, lecithin, higher fatty acid amides and the like.

The substrate of the inkjet recording paper of the present invention is not particularly limited, and is a paper substrate such as acid paper or neutral paper used for general coated paper, various synthetic resin film sheets, laminated paper, and the like. Are used as appropriate.
However, when adopting a cast method or a film transfer method, which will be described later, in forming the surface layer, it is preferable to use a gas-permeable substrate, and a paper substrate or a resin film sheet having gas permeability can be used.

The paper base is composed mainly of wood pulp and a pigment (filler) blended as necessary. As the wood pulp, various chemical pulps, mechanical pulps, regenerated pulps and the like can be used, and these pulps can be beaten by a beating machine in order to adjust paper strength, papermaking suitability, and the like.
Here, the beating degree (freeness) of the pulp is not particularly limited, but is generally about 250 to 550 ml (CSF: JIS-P-8121).
In addition, chlorine-free pulp such as so-called ECF pipe and TCF pipe can be preferably used.
The pigment blended as needed is blended for the purpose of imparting opacity or adjusting the ink absorbability, and uses, for example, calcium carbonate, calcined kaolin, silica, titanium oxide and the like. be able to. In this case, about 1-20 mass% is preferable with respect to the whole base material. If the amount is too large, the paper strength may decrease.
In addition, a sizing agent, a fixing agent, a paper strength enhancer, a cationizing agent, a yield improving agent, a dye, a fluorescent brightening agent, and the like can be added as an auxiliary agent.

The base material can be coated and impregnated with starch, polyvinyl alcohol, cationic resin, etc. in the size press process of the paper machine, and the surface strength, sizing degree, etc. can be adjusted. About 200 seconds is preferable. If the sizing degree is low, there may be a problem in operation such as wrinkling during coating. On the other hand, if the sizing degree is high, the ink absorbability decreases and the ink shows through. And cockling may be noticeable. In addition, although the basic weight of a base material is not specifically limited, Usually, it is about 20-400 g / m < ² >.

  In the inkjet recording paper of the present invention, when a plurality of coating layers are formed on a substrate, a layer containing (A) an anionic colloidal silica treated with a coupling agent and (B) a polymer is a surface layer. In addition, an undercoat layer can be provided between the surface layer and the substrate, and by providing such an undercoat layer, the ink absorption capacity and the absorption speed can be increased. In this case, a plurality of layers each including the components (A) and (B) and the undercoat layer may be formed.

Here, the undercoat layer preferably contains a pigment and an adhesive as main components.
Examples of the pigment contained in the undercoat layer include kaolin, clay, calcined clay, amorphous silica (also referred to as amorphous silica), synthetic amorphous silica, and colloidal silica, which are commonly used in the coated paper manufacturing field. , Zinc oxide, aluminum oxide, aluminum hydroxide, calcium carbonate, satin white, aluminum silicate, alumina, zeolite, synthetic zeolite, sepiolite, smectite, synthetic smectite, magnesium silicate, magnesium carbonate, magnesium oxide, diatomaceous earth, styrene plastic pigment, Hydrotalcite, urea resin-based plastic pigment, benzoguanamine-based plastic pigment, and the like can be used singly or in appropriate combination of two or more. Among these, it is preferable to use amorphous silica, alumina, or zeolite having high ink absorbability as a main component.

  On the other hand, examples of the adhesive contained in the undercoat layer include casein, soy protein, synthetic protein and other starches commonly used in the field of coated paper production, various starches such as starch and oxidized starch, and polyvinyl alcohol. , Cationic polyvinyl alcohol, polyvinyl alcohols containing modified polyvinyl alcohol such as silyl modified polyvinyl alcohol, cellulose derivatives such as carboxymethyl cellulose and methyl cellulose, styrene-butadiene copolymer, conjugated diene polymer of methyl methacrylate-butadiene copolymer Latex, acrylic polymer latex, vinyl polymer latex such as ethylene-vinyl acetate copolymer and the like can be used singly or in appropriate combination of two or more.

In this case, the blending ratio of the pigment and the adhesive is generally adjusted in the range of 1 to 100 parts by weight, preferably 2 to 50 parts by weight with respect to 100 parts by weight of the pigment, although it depends on the type.
In addition, in the undercoat layer, in addition to the pigment and the adhesive, various auxiliary agents such as a dispersant, a thickener, an antifoaming agent, an antistatic agent and an antiseptic used in the production of general coated paper, Fluorescent dyes, colorants and the like can be added as appropriate.

  Moreover, it is preferable to mix a cationic compound in the undercoat layer for the purpose of fixing the dye component in the ink for ink jet recording. That is, by adding a cationic resin to the undercoat layer, the surface layer containing the anionic colloidal silica formed on the (A) coupling agent formed thereon is agglomerated and penetrates into the surface layer forming coating solution. The surface layer having particularly excellent gloss can be obtained.

Examples of such a cationic compound include a cationic resin and a low molecular weight cationic compound (for example, a cationic surfactant), and it is preferable to use a cationic resin from the viewpoint of the effect of improving the printing density. The cationic compound is preferably used as a water-soluble resin or emulsion.
Further, it can be used as a cationic organic pigment in which a cationic resin is insolubilized by means of crosslinking or the like to form a particulate form. This cationic organic pigment is obtained by copolymerizing a polyfunctional monomer into a crosslinked resin when polymerizing a cationic resin, or a reactive functional group (hydroxyl group, carboxyl group, amino group, acetoacetyl group, etc.). A crosslinking agent is added to the cationic resin as necessary, and a crosslinked resin is obtained by means such as heat and radiation. The cationic compound, particularly the cationic resin, may play a role as an adhesive.

The following can be illustrated as said cationic compound. Specifically, 1) polyalkylene polyamines such as polyethylene polyamine and polypropylene polyamine or derivatives thereof, 2) acrylic resin having secondary amine group, tertiary amine group or quaternary ammonium group, 3) polyvinyl amine , Polyvinylamidines, 4) a dicyan cationic resin represented by a dicyandiamide-formalin polycondensate, 5) a polyamine cationic resin represented by a dicyandiamide-diethylenetriamine polycondensate, 6) an epichlorohydrin-dimethylamine addition polymer, 7 ) dimethyldiallylammonium chloride -SO ₂ copolymer, 8) diallylamine salt -SO ₂ copolymer, 9) dimethyldiallylammonium chloride polymer, 10) polymers of allylamine salts, 11) dialkylaminoethyl (meth) And cationic compounds such as acrylate quaternary salt polymer and 12) acrylamide-diallylamine salt copolymer. These cationic compounds also have the effect of improving the printed image water resistance.

1-100 mass parts is preferable with respect to 100 mass parts of pigments contained in an undercoat layer, and, as for the cationic compound mix | blended with the said undercoat layer, More preferably, it is 5-50 mass parts. If the blending amount is small, the effect of improving the printing density and printing water resistance may not be sufficiently obtained. If the blending amount is large, the printing density may be lowered or the image may be blurred.
The undercoat layer forming coating liquid comprising the above-described components is generally adjusted to a solid content concentration of about 5 to 50% by mass, and about ² to 100 g / m ² in terms of dry mass on the paper substrate. The undercoat layer is formed by coating preferably at about 5 to 50 g / m ² , more preferably about 10 to ²⁰ g / m ² .

  In this case, if the coating amount of the coating liquid for forming the undercoat layer is small, the ink absorbability improving effect is not sufficiently exhibited, and bleeding of the recorded image and a decrease in the gloss improving effect when the surface layer is provided are caused. In addition, if base paper is used as the base material, the amount of ink absorbed by the base paper increases, and as a result, the paper after recording causes rippling (cockling), and the spur of the printer (paper suppression roll and gear after recording) ) May cause problems such as noticeable press marks (spurs). On the other hand, if the coating amount is large, the printing density may be lowered and the strength of the coating layer (undercoating layer) may be reduced, and problems such as easy powdering and scratching may occur.

  The coating method is not particularly limited, and various publicly known coating apparatuses such as a blade coater, an air knife coater, a roll coater, a brush coater, a champlex coater, a bar coater, a lip coater, a die coater, a gravure coater, and a curtain coater. Apply and dry by

In the present invention, the surface layer containing (A) the anionic colloidal silica treated with the coupling agent and (B) the polymer, the coating liquid containing these components can be applied directly on the substrate or the above. It can be coated on the undercoat layer.
In this case, the coating liquid can be applied on a substrate or undercoat layer, dried, and then smoothed by a supercalender, etc., to give gloss, but high gloss and excellent ink jet recording suitability In view of the above, it is preferable to adopt a cast method or a film transfer method (hereinafter referred to as “cast method”) using a mirror drum described later.

In general, the casting method means that the coating layer is dried on a smooth cast drum (mirror finish metal, plastic, glass, etc.), mirror finish metal plate, plastic sheet, film, or glass plate. In this method, a smooth and glossy coating layer surface is obtained by copying a smooth surface onto the coating layer.
In the present invention, as a method of providing a surface layer by a casting method using a heated mirror drum, the coating liquid is applied directly on a base material or on an undercoat layer provided on the base material, and (1 ) Method to press and dry the heated mirror drum while this coating layer is in a wet state (wet casting method), (2) After re-wetting after drying once, press to the heated mirror drum, A method of drying and finishing (rewet casting method), (3) gelation casting method, (4) coating the coating liquid directly on the heated mirror drum, and then providing it on the substrate surface or on the substrate For example, a method (precast method) of pressing and drying to the surface of the undercoat layer can be used. The temperature of the mirror drum heated in the above method is, for example, 50 to 150 ° C, preferably 70 to 120 ° C.

As the film transfer method, (1) the surface layer forming coating solution is applied to the surface of the base material or the surface of the undercoat layer provided on the base material, and the coating layer is in a wet state. A method in which a smooth film or sheet is stacked and dried, followed by peeling and finishing the smooth film or sheet. (2) Anionic colloidal silica treated with a coupling agent on the smooth film or sheet (A) (B) A base layer to be bonded while a coating layer is provided by coating a surface layer-forming coating solution containing a polymer (emulsion) and the coating layer is in a wet state. There is a method in which the surface or undercoat layer surface is wet to some extent, and after both are pressed and dried, a smooth film or sheet is peeled off and finished.
In this case, the smooth film or sheet preferably has a surface roughness (JIS-B-0601) of Ra = 0.5 μm or less, and more preferably Ra = 0.05 μm or less.

Among the above cast methods, the cast method using a heated mirror surface tends to be superior in surface smoothness compared to the film transfer method, and is more advantageous in terms of productivity and cost. It is preferable in that there are many.
Further, the coating amount of the surface layer forming coating solution is preferably 1 to 30 g / m ² on a dry solids, more preferably 2 to 20 g / m ^2, and more preferably from 3 to 15 g / m ^2. Here, if it is less than 1 g / m ² , the print density and gloss may not be sufficiently obtained. If it exceeds 30 g / m ² , the effect is saturated, drying is burdened, and operability may be reduced. In addition, after providing a coating layer by cast finishing, a smoothing process can also be performed by a super calendar etc. further.

  In the above casting methods, when applying the surface layer forming coating solution, various known coating methods can be used, for example, blade coater, air knife coater, roll coater, brush coater, Champlex coater, A coating method using a coating apparatus such as a bar coater or a gravure coater can be employed.

  The ink jet recording paper of the present invention described above is a recording body excellent in glossiness. In particular, the 75 ° glossiness (JIS-Z-8741) of the surface of the recording surface is preferably 30% or more, More preferably, it is 40% or more, More preferably, it is 65% or more. In this case, there is no particular upper limit, but it is, for example, 95%. With such an ink jet recording paper having excellent glossiness, a high-quality recorded image with excellent image quality and photographic tone can be obtained.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to the following Example. In the following description, “mass%” and “part by mass” are abbreviated as “%” and “part”, respectively, unless otherwise specified.

[1] Preparation of paper base material 100 parts of wood pulp (LBKP; freeness 500 mlCSF), 9 parts of calcined kaolin (trade name: Ansilex, Engelhard & Minerals), 0.05 part of commercial sizing agent (PM356, Arakawa Chemical Co., Ltd.), 1.5 parts of sulfuric acid band, 0.5 parts of wet paper strength agent (WS570 manufactured by Nippon PMC), and 0.75 parts of starch are used. A paper substrate of / m ² was produced. This paper substrate had a Steecht size of 10 seconds. In the following examples and comparative examples, this paper substrate was used.

[2] Production of anionic colloidal silica treated with a coupling agent [Production Example 1]
An apparatus equipped with a stirrer, a thermometer, a reflux condenser, and a dropping funnel was charged with 985 parts of anionic colloidal silica having an average particle size of 50 nm and a solid content of 40% (catalyst chemical industry Co., Ltd .: Cataloid SI-45P). And heated to 75 ° C. Next, 15 parts of γ-glycidoxypropylmethyldimethoxysilane was added dropwise over 15 minutes while maintaining at 75 ° C. with stirring, and the reaction was completed by incubating at the same temperature for 30 minutes. This was cooled to obtain an anionic colloidal silica (S-1) treated with a coupling agent.

[Production Example 2]
The same procedure as in Production Example 1 was performed except that the anionic colloidal silica was changed to one having an average particle size of 30 nm and a solid content of 30% (manufactured by Nippon Chemical Industry Co., Ltd., Silica Doll-30), and a coupling agent An anionic colloidal silica (S-2) treated with the above was obtained.

[3] Production of polymer emulsion [Production Example 3]
In an apparatus equipped with a stirrer, thermometer, reflux condenser, dropping funnel and nitrogen introduction tube, 641 parts of deionized water, 9 parts of sodium salt (emulsifier) of polyoxyethylene (n = 5) lauryl ether sulfate and the following table 10 parts of the monomer composition shown in 1 was charged and heated to 75 ° C. under a nitrogen stream. Next, while maintaining at 75 ° C. with stirring, 10 parts of a deionized aqueous solution in which 1.5 parts of ammonium persulfate was dissolved was added to initiate the polymerization reaction. Next, 290 parts of the remaining monomer composition was added dropwise over 2 hours while maintaining the temperature at 75 ° C. Further, the polymerization reaction was completed by incubating at the same temperature for 1 hour. After cooling, the pH was adjusted to 8.0 with 10% ammonia water and diluted with deionized water to obtain a copolymer emulsion 1 having a solid content of 30%, a glass transition temperature of 70 ° C., and an average particle size of 0.053 μm. .

[Production Example 4]
A copolymer emulsion 2 having a solid content of 30%, a glass transition temperature of 63 ° C., and an average particle size of 0.061 μm was obtained except that the monomer composition was changed to the composition shown in Table 2 below. Got.

[Production Example 5]
In a reactor similar to Production Example 3, 490 parts of deionized water and 13 parts of the emulsion of the monomer composition shown in Table 3 below were charged and heated to 70 ° C. under a nitrogen stream. Subsequently, while maintaining the temperature at 70 ° C. with stirring, 10 parts of a deionized aqueous solution in which 2.3 parts of sodium persulfate was dissolved was added to initiate the polymerization reaction. Subsequently, 640 parts of the emulsion of the remaining monomer composition was added dropwise over 3 hours while maintaining the temperature at 100 ° C. Further, the polymerization reaction was completed by incubating at the same temperature for 1 hour. After cooling, the pH is adjusted to 7.7 with 10% sodium hydroxide and diluted with deionized water to obtain a copolymer emulsion 3 having a solid content of 40%, a glass transition temperature of 91 ° C., and an average particle size of 0.085 μm. Obtained.

Table 4 summarizes the monomer composition, glass transition temperature, and average particle size of the copolymer emulsions 1 to 3 obtained in Production Examples 3 to 5. The average particle diameter is a value measured with an electrophoretic light scattering photometer (ELS-800, manufactured by Otsuka Electronics Co., Ltd.).
In Table 4, St is styrene, MMA is methyl methacrylate, BA is n-butyl acrylate, EA is ethyl acrylate, EMA is ethyl methacrylate, MAA is methacrylic acid, and AA is acrylic. Acid, MAm represents methacrylamide.

[4] Production of water-soluble polymer [Production Example 6]
10 parts of commercially available polyvinyl alcohol (PVA217, manufactured by Kuraray Co., Ltd.) was added to 90 parts of ion-exchanged water, heated to 50 ° C., stirred for 2 hours with a stirrer, and 10% aqueous polyvinyl alcohol solution (water-soluble polymer 1). )

[5] Performance evaluation of inkjet recording paper [Example 1]
On the paper substrate, the following undercoat layer-forming coating solution was applied and dried with an air knife coater so that the dry mass was 15 g / m ² . Next, the following surface layer-forming coating solution is applied onto the undercoat layer with a roll coater, immediately pressed against a mirror drum having a surface temperature of 80 ° C., dried, and released to obtain a glossy ink jet recording paper. Obtained. The coating amount of the surface layer at this time was 10 g / m ² in terms of solid content.

[Coating liquid for forming undercoat layer] (Solid content concentration: 17%, part indicates solid content part by mass)
100 parts of amorphous silica (specific surface area 340 m ² / g, average secondary particle diameter 4.5 μm, trade name; Fine Seal X-45, manufactured by Tokuyama Corporation) as a pigment, and silyl-modified polyvinyl alcohol (adhesive) Product name: R1130; 25 parts by Kuraray Co., Ltd., 5 parts of dicyandiamide resin (Neofix E-117; Nikka Chemical Co., Ltd.) as a cationic resin, and cationic acrylamide resin (Smiletz resin SR1001) ; 15 parts by Sumitomo Chemical Co., Ltd.), 2 parts fluorescent dye (Whiteex BPSH; made by Sumitomo Chemical), 0.5 parts of sodium polyphosphate as a dispersant, and an undercoat layer forming coating solution with a solid content of 18% Was prepared.

[Coating liquid for surface layer formation] (solid content concentration 12%, part indicates solid content part by mass)
The coupling agent-treated anionic colloidal silica S-1 synthesized in Production Example 1 and the polymer emulsion 1 obtained in Production Example 3 were mixed so that the solid content ratio was 9/1, and purified water was used. A composition having a solid content of 45% was prepared by dilution.
A coating solution for forming a surface layer having a solid content concentration of 30% comprising 1 part of an alkyl vinyl ether / maleic acid derivative copolymer as a thickening / dispersing agent and 2 parts of lecithin as a release agent is prepared for 100 parts of the composition. did.

[Examples 2 to 5]
Coating for surface layer formation by changing the solid content ratio of the coupling agent-treated anionic colloidal silica (S-1) and the polymer emulsion 1 to 7/3, 5/5, 3/7, and 1/9, respectively. A glossy ink jet recording paper was obtained in the same manner as in Example 1 except that the liquid was prepared and used.

[Example 6]
A glossy ink jet recording paper was obtained in the same manner as in Example 1 except that the polymer emulsion 1 was changed to the polymer emulsion 2 obtained in Production Example 4.

[Examples 7 to 10]
Coating for surface layer formation by changing the solid content ratio of the coupling agent-treated anionic colloidal silica (S-1) and the polymer emulsion 2 to 7/3, 5/5, 3/7, and 1/9, respectively. A glossy ink jet recording paper was obtained in the same manner as in Example 6 except that the liquid was prepared and used.

[Examples 11 to 14]
Except that the coupling agent-treated anionic colloidal silica and polymer emulsion shown in Table 5 below were used, and the composition ratio (solid content ratio) of the polymer emulsion to the anionic colloidal silica was changed to 7/3. A surface layer forming coating solution was prepared in the same manner as in Example 1, and a glossy ink jet recording paper was obtained in the same manner as in Example 1.

[Example 15]
Coupling agent-treated anionic colloidal silica (S-1) and polymer emulsion 1 were mixed so that the solid content ratio was 9/1, and diluted with purified water to prepare a composition having a solid content of 45%. . To 50 parts of this composition, 50 parts of anionic colloidal silica (S-3) having an average particle size of 0.045 μm, pH of 9.5 and a solid content of 40%, and an alkyl vinyl ether / maleic acid derivative as a thickener / dispersant A coating liquid for forming a surface layer having a solid content concentration of 30% comprising 1 part of a coalescence and 2 parts of lecithin as a release agent was prepared, and a glossy ink jet recording paper was obtained in the same manner as in Example 1.

[Example 16]
In the same manner as in Example 1, the coating solution for forming the undercoat layer was coated on a paper substrate with an air knife coater so as to have a dry mass of 15 g / m ² and dried. Next, the surface layer forming coating solution used in Example 1 was applied onto the above-mentioned undercoat layer with an air knife coater, dried, and then subjected to a thermal super calender (calendar surface temperature of 100 ° C.) at a pressure of 500 N / cm. The glossy ink jet recording paper was obtained twice. The coating amount of the surface layer at this time was 10 g / m ² in terms of solid content.

[Example 17]
The surface layer / surface layer forming coating solution used in Example 1 was directly coated on a paper substrate with an air knife coater, and after drying, a thermal super calender (calendar surface temperature was 100 ° C.) at a pressure of 500 N / cm. The glossy ink jet recording paper was obtained twice. The coating amount of the surface layer at this time was 10 g / m ² in terms of solid content.

[Example 18]
A glossy ink jet recording paper was obtained in the same manner as in Example 1 except that the polymer emulsion 1 was changed to the water-soluble polymer 1 obtained in Production Example 6.

[Comparative Examples 1 and 2]
The same as Example 1 except that anionic colloidal silica (S-3) and polymer emulsion having an average particle size of 0.045 μm, pH 9.5 and solid content of 40%, which were not treated with a coupling agent, were used. A glossy ink jet recording paper was obtained.

[Comparative Examples 3 and 4]
Coupling agent-treated anionic colloidal silica (S-1) and (S-2) were prepared in the same manner as in Example 1 except that a surface layer-forming coating solution was prepared and each was used. Inkjet recording paper was obtained.

Dye-based inks (MJIC7, PMIC1C, both Seiko Epson) were used for the ink jet recording papers obtained in Examples 1 to 18 and Comparative Examples 1 to 4 using an ink jet printer (PM-750C, manufactured by Seiko Epson Corporation). (Manufactured by Co., Ltd.) and evaluated for ink jet suitability (solid uniformity of printed portion, print bleeding, print density after ink jet recording), glossiness, surface strength and transportability in the recording apparatus. The results are shown in Table 5.
In addition, each of the ink jet recording papers described above is pigmented ink (ICBK22, ICC22, ICY22, all manufactured by Seiko Epson Corporation) using an ink jet printer (PX-V700, manufactured by Seiko Epson Corporation) that is compatible with pigment ink. Were used for full-color printing, and were evaluated for ink jet suitability (solid uniformity of the printed part, print bleeding) and scratch resistance. The results are shown in Table 6.

In Tables 5 and 6, each item was evaluated according to the following criteria.
[1] Inkjet recording suitability [1-1] Solid uniformity of printing portion The printing unevenness (darkness unevenness) of a solid printing portion of a two-color mixture of cyan ink and magenta ink was visually evaluated.
◎: Good level with no printing unevenness ○: Printing unevenness is slightly seen, but there is no problem in practical use △: There is some printing unevenness, practically slightly problematic level ×: Printing unevenness is remarkable, practical use The level that is the most serious problem

[1-2] Printing bleeding Solid printing portions of black, cyan, magenta, and yellow color inks were printed so that the boundary portions were in contact with each other, and blurring at the boundaries was visually evaluated.
A: Good level with no blurring B: Slight blurring, but no problem in practical use B: Slight blurring, slightly problematic level in practical use ×: Significant blurring, serious practical problem Level [1-3] Print Density after Inkjet Recording The print density of the black solid print portion was measured with Macbeth RD-914.

[2] Glossiness The 75 ° glossiness of the surface was measured by a method according to JIS-Z-8741.
[3] Surface Strength A mending tape (Scotch 810: width 12 mm, length 3 cm) was applied to the surface of the recording paper, uniformly pressed, peeled off after 3 seconds, and the state taken on the tape was visually evaluated.
○: Almost no peeling Δ: Although there is some peeling, there is no problem in general use ×: Level where peeling occurs considerably and becomes a serious problem in practical use

[4] Transportability in recording apparatus Ten sheets of paper were loaded on an ink jet printer PM750C (manufactured by Seiko Epson Corporation), and continuous printing was performed, and the state of transport was observed. The number of sheets that can be transported without any problem in practice is displayed (unable to transport 9 sheets or more).

[5] Scratch resistance After 2 minutes had passed after printing, the printed surface was lightly rubbed 3 times with tissue paper, and how much the recorded image was retained was visually evaluated according to the following criteria.
A: The recorded image is almost completely retained. O: The recorded image is slightly retained, and the original image can be read sufficiently. Δ: The recorded image has lost its clarity. It is difficult to determine what is X: Most of the pigment-based ink on the surface has disappeared

As shown in Table 5, the inkjet recording paper of the present invention of Examples 1 to 18 has a surface layer containing (A) an anionic colloidal silica treated with a coupling agent and (B) a copolymer. Therefore, it can be seen that the printability, glossiness, surface strength, and transportability when printing with dye-based ink are superior to those of the comparative example. Moreover, the composition ratio (solid content mass ratio) of the component (A) and the component (B) is from 1/9 to 9/1 to 3/7 to 7/3, or 3/7 to 5/5. As can be seen, each evaluation item is improved in a balanced manner.
In addition, as shown in Table 6, the inkjet recording papers of the present invention of Examples 1 to 18 are superior in printability and scratch resistance when printed with pigment-based inks compared to those of Comparative Examples, It can be seen that pigment-based ink also exhibits excellent ink jet aptitude.

  Examples 16 and 17 are not cast coating, but are subjected to thermal calendering after coating with an air knife coater, but a surface layer containing anionic colloidal silica treated with the coupling agent of the present invention and a polymer. It can be seen that a recording paper having a considerably high glossiness and excellent printability and transportability can be obtained without using a casting method.

Claims (8)

An inkjet recording paper having a substrate and at least one coating layer formed on the substrate,
At least a surface layer of the coating layer contains (A) anionic colloidal silica treated with a coupling agent, and (B) a polymer. An inkjet recording paper having a substrate and a surface layer formed on the substrate,
The ink jet recording paper, wherein the surface layer contains (A) anionic colloidal silica treated with a coupling agent and (B) a polymer.   The inkjet recording paper according to claim 1 or 2, wherein the polymer (B) is applied as a polymer emulsion on the substrate, and the average particle size of the polymer emulsion is 0.02 to 0.15 µm.   The inkjet recording paper according to claim 1, wherein the coupling agent is a silane coupling agent.   The inkjet recording paper according to any one of claims 1 to 4, wherein the surface layer further contains (C) anionic colloidal silica. The polymer (B) is a copolymer obtained by copolymerizing the following monomers (a) to (d) at the ratio shown below, and the copolymer has a glass transition temperature of 0 to 200 ° C. The inkjet recording paper according to claim 1, wherein the inkjet recording paper is provided.
(A) At least one monomer selected from styrene and α-methylstyrene: 5 to 95% by mass
(B) At least one monomer selected from acrylic acid ester and methacrylic acid ester represented by the following general formula (1): 0.5 to 94.5% by mass

(In the formula, R ¹ represents a hydrogen atom or a methyl group, and R ² represents a saturated or unsaturated linear or branched aliphatic hydrocarbon group having 1 to 22 carbon atoms.)
(C) At least one monomer selected from α, β-unsaturated carboxylic acid and salts thereof: 0.5 to 30% by mass
(D) Monomer copolymerizable with monomers (a) to (c): 0 to 20% by mass   The inkjet recording paper according to any one of claims 1 to 6, wherein the surface layer is formed by a casting method. The inkjet recording paper according to any one of claims 1 to 7, wherein the surface has a 75 ° glossiness of 30% or more as measured by a method according to JIS-Z-8741.