JP2006346914A - Manufacturing method of inkjet recording glossy cast-coated paper, coating liquid using thereto and glossy cast-coated paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the manufacturing method of an inkjet recording medium, which is excellent in ink absorbency, surface gloss and image quality and in which no microcrack develops. <P>SOLUTION: In this manufacturing method of the inkjet recording medium, after an upperlayer coating liquid including a polymer emulsion having a polymer compound (A), which shows hydrophilic nature in a temperature range not higher than a certain temperature (a temperature sensing point) and hydrophobic nature in a temperature range exceeding the temperature sensing point, is coated on an underlayer formed by a coating liquid including at least a pigment, a binder and polyhydric alcohols on a support and, while the coating layer is being under a moist state, the coating layer is brought into a pressingly contact with a heated solid mirror-finished surface so as to give gloss to the surface of the coated layer. Further, the coating liquid and the inkjet recording medium are provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a glossy cast paper for inkjet which has excellent ink absorbability and has no microcracks, a coating liquid useful for efficiently producing the glossy cast paper, and a method for producing the glossy cast paper.

The ink jet recording system has been used in a wide range of fields because it has low noise during recording, can be easily colored, and can perform high-speed recording.
However, high-quality paper used for general printing is inferior in ink absorbability and drying properties, and is inferior in image quality such as resolution, so special paper that improves these has been proposed, and ink color development and reproducibility have been proposed. In order to increase the recording medium, recording media coated with various inorganic pigments including amorphous silica have been developed (Patent Documents 1 and 2).

  In recent years, technological development of an ink jet recording medium for obtaining a high image quality equivalent to that of a silver salt photograph has been advanced. As a method for imparting such glossiness to the surface of a recording medium, a cast coating method is widely known. . In the cast coating method, a coating liquid composition mainly composed of a pigment or an adhesive is coated on a base paper, and then pressed onto the surface of a heated drum that is mirror-finished while the coating layer is in a wet state. Wet cast method (direct method) to dry, exfoliate, and wet coating layer once dried or semi-dried to solidify, then wet plasticized with rewetting liquid, and crimped to mirror-finished heated drum 3) of the rewet cast method for drying and peeling, and the gelled cast method (coagulation method) for bringing the wet coating layer into a gel state by coagulation treatment, pressing onto a mirror-finished heating drum, drying and peeling off. Various types of methods are generally known, and in each of these casting methods, the coating layer in a wet plasticized state is pressed on a heated drum that has been mirror-finished, dried, peeled off from the heated drum, and then mirror-finished. Copy It is common to take. The casting method is said to be excellent in terms of productivity, and the surface of the recording medium obtained by the casting method is highly glossy and highly smooth, but the surface of the coating layer is a micrometer of a few microns or less. There are many cracks in the form of ground cracks (hereinafter referred to as “microcracks”), and there is a problem that it is difficult to obtain a high resolution image.

  A method for producing an inkjet recording medium that does not generate the microcracks is disclosed in Patent Document 3, and a solution is achieved by including a (meth) acrylamide copolymer or a resin having a lactam group. Since an emulsion is not formed, the viscosity when added to the coating liquid tends to be high, and in order to perform a uniform and smooth coating, it is necessary to keep the content of the resin in the coating liquid low. Yes, the effect was limited.

  Recently, a polymer emulsion containing a thermosensitive polymer compound and an ink receiving layer formed on the outermost surface using the polymer emulsion, and a method for producing glossy cast glossy paper with high gloss and high printability have been disclosed in Patent Document 4, Patent It is disclosed in Document 5. However, due to the expansion of applications such as high-speed inkjet recording, high-definition recording images, and full-color recording, higher printability such as higher gloss, higher image quality, and higher recording density, or pigment ink and dye ink It is not enough to meet the broad demand for adaptation.

JP-A-55-51583 JP-A-56-148585 JP 2000-218927 A JP 2003-40916 A JP 2005-35277 A

  The present invention relates to a coating liquid that is excellent in ink absorptivity, surface gloss and image quality and does not generate microcracks, a method for producing glossy cast paper for ink jet using the coating liquid, and an ink jet produced by the production method The object is to provide glossy cast paper.

  As a result of various studies to solve the above problems, the present inventors applied a lower layer coating solution containing at least a pigment, a binder, and a polyhydric alcohol on the support, and further fixed on the lower layer. An upper layer coating solution containing a polymer emulsion containing a polymer compound (A) that exhibits hydrophilicity in the temperature range below the temperature (temperature sensitive point) and exhibits hydrophobicity in the temperature range above the temperature sensitive point is applied. A method for producing a glossy cast paper for ink jet, characterized in that after coating, the coating layer is pressed onto a heated mirror-finished solid surface while the coating layer is in a wet state, and gloss is imparted to the surface of the coating layer And it discovered that the above-mentioned coating liquid was effective in the solution of the said problem, and came to make this invention.

That is, the present invention is as follows.
(1) A lower layer coating solution containing at least a pigment, a binder, and a polyhydric alcohol is coated on a support, and the hydrophilicity is exhibited in a temperature range below a certain temperature (temperature sensitive point) on the lower layer. In the temperature range exceeding the temperature sensitive point, after coating the upper layer coating liquid containing the polymer emulsion containing the hydrophobic polymer compound (A), the coating layer is heated in a wet state. A method for producing a glossy cast paper for ink-jet printing, comprising: applying pressure to a mirror-finished solid surface to impart gloss to the surface of the coating layer.

(2) The method for producing glossy cast paper for ink jet according to (1), wherein the binder is polyvinyl alcohol.
(3) The method for producing glossy cast paper for ink jet according to (1) or (2), wherein the polyhydric alcohol is a plasticizer of polyvinyl alcohol.
(4) The polymer emulsion contains 50% by mass or more of a nonionic N-substituted (meth) acrylamide derivative, and exhibits a hydrophobic property at a temperature sensitive point of 25 ° C. or lower and / or a temperature region exceeding 25 ° C. The method for producing glossy cast paper for ink jet according to any one of (1) to (3) above, wherein the emulsion is a polymer emulsion containing the molecular compound (A).

(5) The above (1) to (4), comprising a step of cooling to a temperature below the temperature sensitive point after coating on the support at a temperature exceeding the temperature sensitive point of the polymer compound (A). The manufacturing method of the glossy cast paper for inkjet as described in any one of these.
(6) The coating liquid used for the manufacturing method of the glossy cast paper for inkjet as described in any one of said (1)-(5).
(7) Glossy cast paper for inkjets manufactured by the method for manufacturing glossy cast paper for inkjets according to any one of (1) to (5) above.

  INDUSTRIAL APPLICABILITY According to the present invention, a coating liquid that is excellent in ink absorbability, surface gloss and image quality and does not generate microcracks, a method for producing glossy cast paper for ink jet using the coating liquid, and an ink jet produced by the production method Glossy cast paper could be provided.

The present invention will be specifically described below.
Examples of the lower layer pigment used in the present invention include kaolin, delaminated kaolin, clay, aluminum hydroxide, satin white, heavy calcium carbonate, light calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide, calcined kaolin, talc, Colloidal silica, dry silica, wet silica, wet pulverized product of silica aggregate, zinc oxide, zinc carbonate, zinc sulfide, alumina, particulate alumina, diatomaceous earth, calcined diatomaceous earth, aluminum silicate, calcium silicate, magnesium silicate, magnesium oxide Mineral pigments such as magnesium carbonate, aluminosilicate, activated clay, bentonite, zeolite, sericite, lithopone, porous pigment, polystyrene resin, urea resin, acrylic resin, melamine resin, benzoguanamine resin, and other organic pigments Is . Preferably, colloidal silica, dry silica, wet silica, or a wet pulverized product of silica aggregate is used.

  Examples of the binder for the lower layer used in the present invention include gelatin or gelatin derivatives, polyvinyl pyrrolidone, pullulan, polyvinyl alcohol or derivatives thereof, polyethylene glycol, carboxymethyl cellulose, hydroxyethyl cellulose, dextran, dextrin, polyacrylic acid and salts thereof, agar , Κ-carrageenan, λ-carrageenan, ι-carrageenan, xanthene gum, locust bean gum, alginic acid, gum arabic, pullulan, casein, soy protein, synthetic protein and other starches, various starches such as starch and oxidized starch, etc. The polyalkylene oxide copolymerizable polymers, water-soluble polyvinyl butyral described in Kaihei 7-195826 and 7-9757, or JP-A-62-245260 It can be mentioned polymers such as a copolymer having repeat alone or of these vinyl monomers vinyl monomer having a carboxyl group or a sulfonic acid group of the mounting. These binders may be used alone or in combination of two or more. A preferred binder is polyvinyl alcohol or a derivative thereof.

  As the polyvinyl alcohol preferably used in the present invention, those having an average degree of polymerization of 300 to 4000 are preferably used. Particularly, those having an average degree of polymerization of 1000 or more have good viscosity increase at the time of coating, and can be obtained. It is preferable because the film strength of the work layer is good. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, particularly preferably 80 to 100%.

  A preferable addition amount of the binder is 5 to 100% by mass, and more preferably 20 to 50% by mass with respect to 100% by mass of the pigment for the lower layer. If the added amount of the binder is less than 5% by mass, the strength of the lower layer cannot be said to be sufficient, and if it exceeds 100% by mass, the ink absorbability tends to decrease.

In the glossy cast paper for inkjet of the present invention, the binder may be hardened with a hardener in order to obtain high strength of the coating layer.
The hardener is generally a compound having a group capable of reacting with the binder or a compound that promotes the reaction between different groups of the hydrophilic binder, and is appropriately selected according to the type of the binder. It is done. For example, boric acid and its salts are preferably used for polyvinyl alcohol.

In the present invention, polyhydric alcohols are aliphatic or alicyclic compounds containing two or more hydroxyl groups and derivatives thereof. Specifically, ethylene glycol derivatives such as ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol isopropyl ether, ethylene glycol monobutyl ether, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, etc. Diethylene glycol derivatives, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, and other triethylene glycol derivatives, polyethylene glycol, propylene glycol, propylene glycol monomethyl ether, propylene Propylene glycol derivatives such as ethylene glycol monoethyl ether, propylene glycol monobutyl ether, polypropylene glycol, trimethylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,5 pentanediol, Examples include hexylene glycol, octylene glycol, glycerol, glycerol monoacetate, glycerol diacetate, glycerol triacetate, glycerol derivatives such as glycerol monobutyrate, 1,2,6-hexanetriol, and the like.

  The polyhydric alcohols play a role of forming a uniform lower layer by suppressing the aggregation of the pigment and the binder. From such a viewpoint, the polyhydric alcohols preferably have excellent compatibility with the binder. Particularly preferred are polyhydric alcohols that can function as plasticizers for polyvinyl alcohol. Examples of polyhydric alcohols that function as plasticizers for polyvinyl alcohol include ethylene glycol, trimethylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, propylene glycol, glycerin, and diethylene glycol. Triethylene glycol and the like are preferably used. These polyhydric alcohols can be used alone or in combination of two or more.

The polyhydric alcohol is preferably added in an amount of 0.5 to 200 parts by mass based on the pigment for the lower layer. More preferably, it is 3 mass%-20 mass%. If it is less than 0.5% by mass, the pigment aggregation suppressing effect cannot be said to be sufficient, and if it exceeds 200% by mass, the drying process may be prolonged.
It is speculated that suppressing the aggregation of the pigment in the lower layer in this way promotes uniform void formation in the lower layer, suppresses non-uniform drying when forming the upper layer, and consequently suppresses microcracks. .

  In the present invention, the “temperature sensitive point” is a temperature at which the hydrophilicity-hydrophobicity of the polymer compound changes, and the “temperature responsiveness” is a property indicating the change in the hydrophilicity-hydrophobicity due to a temperature change. means. In the present invention, the term “hydrophilic” means that in a system in which a polymer compound and water coexist, the polymer compound in a state compatible with water is more stable than the phase separated state. “Hydrophobic” means that in a system in which a polymer compound and water coexist, the polymer compound is more stable in a phase-separated state than water than in a compatible state. The change in hydrophilicity-hydrophobicity is, for example, a sudden change in viscosity accompanying a temperature change in a system in which a polymer compound and water coexist, or a rapid change in transparency in a system in which a polymer compound and water coexist. It appears as a rapid change in the solubility of the polymer compound in water. In the present invention, the viscosity is measured when the temperature of the system in which the polymer compound coexists with water is gradually lowered from the temperature range where the polymer compound exhibits hydrophobicity (temperature exceeding the temperature sensing point). The temperature sensitive point of the polymer compound is determined as a transition point at which the obtained temperature-viscosity curve changes rapidly.

The polymer compound (A) used in the present invention exhibits hydrophilicity in a temperature range below a certain temperature (temperature sensing point) and hydrophobicity in a temperature range exceeding the temperature sensing point, and the polymer compound (A) is subjected to homopolymerization to produce the temperature. Homopolymeric polymer compound of monomer (main monomer (M)) or copolymer polymer compound of two or more main monomers (M) from which a polymer compound exhibiting responsiveness (hydrophilicity-hydrophobicity change) is obtained In addition, a monomer (submonomer (N)) that can react with the main monomer (M) to form a polymer compound and cannot obtain a polymer compound exhibiting the temperature responsiveness by homopolymerization. It is a copolymerized polymer compound with the monomer (M). The main monomer (M) and the submonomer (N) can be used alone or in combination of two or more.
A polymer compound having high temperature responsiveness can be obtained by homopolymerization, but by performing the copolymerization, a polymer compound having a temperature sensitive point different from that of the homopolymer polymer compound can be obtained, or a homopolymer polymer A film forming property different from that of the compound can be obtained.

  As the main monomer (M), N-alkyl or N-alkylene-substituted (meth) acrylamide derivatives (here, (meth) acryl is a simple notation of methacryl (or methacryl) or acryl), vinyl Examples include methyl ether. In particular, nonionic N-substituted (meth) acrylamide derivatives are preferable. For example, N-ethyl (meth) acrylamide, N, N-diethylacrylamide, N-isopropyl (meth) acrylamide, N-cyclopropyl (meth) acrylamide, N -Methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, Nn-propyl (meth) acrylamide, N-methyl-Nn-propyl (meth) acrylamide, N-methyl-N-isopropyl (meth) ) Acrylamide, N-tetrahydrofurfuryl (meth) acrylamide, N-methoxypropyl (meth) acrylamide, N-ethoxypropyl (meth) acrylamide, N-isopropoxypropyl (meth) acrylamide, N-ethoxyethyl (meth) acrylamide, - (2,2-dimethoxyethyl) -N- methyl (meth) acrylamide, N- methoxyethyl (meth) acrylamide, N- methylol acrylamide, diacetone acrylamide, such as methylene bisacrylamide. From the viewpoint of film formability (microcrack suppression), N-isopropylacrylamide, Nn-propylacrylamide, N, N-diethylacrylamide, and N, N-dimethylacrylamide are preferable.

  Examples of the auxiliary monomer (N) include lipophilic vinyl compounds, hydrophilic vinyl compounds, and ionic vinyl compounds. Specifically, lipophilic vinyl compounds include methyl (meth) acrylate and ethyl (meth) acrylate. , N-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, glycidyl methacrylate, styrene, α-methylstyrene, ethylene, isoprene, butadiene, vinyl acetate, vinyl chloride, and the like. As the hydrophilic vinyl compound, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, (meth) acrylamide, N-methyl (meth) acrylamide, N-methylol acrylamide, diacetone acrylamide, methylene bisacrylamide, 2-methyl 5-vinylpyridine, N-vinyl-2-pyrrolidone, N-acryloylpyrrolidine, acrylonitrile, and the like. Examples of the ionic vinyl compound include acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, crotonic acid, Carboxylic acid group-containing monomers such as butenetricarboxylic acid, monoethyl maleate, monomethyl maleate, monoethyl itaconate, monomethyl itaconate, 2-acrylamido-2-methyl-propane sulfonic acid, styrene sulfonic acid, vinyl sulfonic acid, (meth) Examples thereof include sulfonic acid group-containing monomers such as acrylic sulfonic acid, and amino group-containing monomers such as N, N-dimethylaminoethyl (meth) acrylate and N, N-diethylaminoethyl (meth) acrylate.

In particular, methyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, styrene, 2-hydroxypropyl (meth) acrylate, acrylamide, methacrylamide, diacetone acrylamide, and methylene bisacrylamide are preferably used. It is done. From the viewpoint of the film formability of the coating layer obtained using the polymer emulsion of the present invention, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, crotonic acid, butenetricarboxylic acid, monoethyl maleate, Carboxylic acid group-containing monomers such as monomethyl maleate, monoethyl itaconate and monomethyl itaconate, sulfonic acid groups such as 2-acrylamido-2-methyl-propane sulfonic acid, styrene sulfonic acid, vinyl sulfonic acid and (meth) acryl sulfonic acid It is preferable to use an anion group-containing monomer such as a containing monomer, and it is particularly preferable to use a carboxylic acid group-containing monomer such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and maleic acid.
The copolymerization ratio of the main monomer (M) and the submonomer (N) is within a range in which the obtained copolymer polymer compound exhibits temperature responsiveness in which hydrophilicity and hydrophobicity reversibly change at a certain temperature as a boundary. It is decided in. That is, when the proportion of the submonomer (N) is too large, the copolymeric polymer compound obtained does not exhibit the temperature responsiveness.

  In the case where the main monomer (M) is preferably contained in an amount of 50% by mass or more, more preferably 70% by mass or more, and still more preferably 80% by mass or more as a constituent component of the polymer compound (A). After coating the coating liquid on the support, the coating layer has a high gloss surface by undergoing a step of pressure-bonding the coating layer to a heated mirror-finished solid surface in a wet state, It has been found that it is possible to produce a recording medium that can provide a higher resolution image with fewer microcracks. That is, the proportion of the main monomer (M) in the main monomer (M) and submonomer (N) used for copolymerization is preferably 50% by mass or more, and more preferably 70% by mass or more. Moreover, 0.01 mass% or more is preferable in order that the addition effect of a submonomer (N) may be expressed better.

  When the polymer emulsion of the present invention is used in the production of an ink jet recording medium, the use of a dye ink having an anionic group in ink jet recording is often more durable than a dye ink having a cationic group. preferable. Therefore, it is preferable to add a cationic compound such as a cationic polymer or cationic particles to the coating liquid for inkjet recording medium for the purpose of fixing the dye ink having an anionic group to the recording medium. From the viewpoint of ease, the polymer compound (A) is more preferably cationic or nonionic. The cationic polymer compound (A) can be obtained, for example, by including an ethylenically unsaturated monomer having a cationic group as a submonomer (N) used for polymerization. It is preferable to use an ethylenically unsaturated monomer having a cationic group as a secondary monomer (N). The ethylenically unsaturated monomers having a cationic group can be used alone or in combination of two or more. In particular, the colloidal stability of the polymer emulsion obtained from the viewpoint of the degree of fading that occurs when a printed matter printed with an inkjet printer is exposed to sunlight or fluorescent light. From the viewpoint, it is more preferable that the ethylenically unsaturated monomer having the cationic group contains a tertiary amino group and / or a quaternary ammonium base.

  The polymer compound (A) containing a tertiary amino group and / or a quaternary ammonium base contains, for example, a main monomer (M) and a tertiary amino group and / or a quaternary ammonium base as a secondary monomer (N). It is obtained by copolymerizing with the monomer to be used. The main monomer (M) and submonomer (N) (including monomers containing a tertiary amino group and / or a quaternary ammonium base) can be used alone or in combination of two or more.

The tertiary amino group or quaternary ammonium base-containing monomer is not particularly limited as long as it has a structure containing a tertiary amino group or quaternary ammonium base in the monomer, but vinyloxyethyltrimethylammonium chloride, 2, 3-dimethyl-1-vinylimidazolinium chloride, trimethyl- (3- (meth) acrylamide-3,3-dimethylpropyl) ammonium chloride, trimethyl- (3-methacrylamidopropyl) ammonium chloride, trimethyl- (3-acrylamide) Propyl) ammonium chloride, N- (1,1-dimethyl-3-dimethylaminopropyl) (meth) acrylamide and its quaternary ammonium salt, trimethyl- (3- (meth) acrylamide) ammonium chloride, 1- Nyl-2-methyl-imidazole, 1-vinyl-2-ethyl-imidazole, 1-vinyl-2-phenyl-imidazole, 1-vinyl-2,4,5-trimethyl-imidazole, N, N-dimethylaminopropyl ( Meth) acrylate and quaternary ammonium salt thereof, N, N-dimethylaminoethyl (meth) acrylate and quaternary ammonium salt thereof, N, N-diethylaminoethyl (meth) acrylate and quaternary ammonium salt thereof, t-butylaminoethyl (Meth) acrylate and its quaternary ammonium salt, N- (3-dimethylaminopropyl) methacrylamide and its quaternary ammonium salt, N- (3-dimethylaminopropyl) acrylamide and its quaternary ammonium salt, N- (3 -Diethylaminopropyl) meta Rilamide and its quaternary ammonium salt, N- (3-diethylaminopropyl) acrylamide and its quaternary ammonium salt, o-, m-, p-aminostyrene and its quaternary ammonium salt, o-, m-, p-vinyl Benzylamine and its quaternary ammonium salt, N- (vinylbenzyl) pyrrolidone, N- (vinylbenzyl) piperidine, N-vinylimidazole and its quaternary ammonium salt, 2-methyl-1-vinylimidazole and its quaternary ammonium salt N-vinylpyrrolidone and its quaternary ammonium salt, N, N′-divinylethyleneurea and its quaternary ammonium salt, α-, or β-vinylpyridine and its quaternary ammonium salt, α-, or β-vinylpiperidine And its quaternary ammonium salts, 2-, and Is exemplified by 4-vinylquinoline and its quaternary ammonium salt. In particular, a methyl chloride quaternary compound of N, N-dimethylaminopropyl methacrylate, N, N-dimethylaminoethyl methacrylate, N, N-dimethylaminopropyl (meth) acrylamide is preferably used.
The copolymerization ratio of the main monomer (M) and the secondary monomer (N) containing a tertiary amino group and / or quaternary ammonium base-containing monomer is such that the resulting copolymeric polymer compound is hydrophilic with respect to the temperature sensitive point. The hydrophobicity is determined within a range exhibiting temperature responsiveness that reversibly changes.

The content of the tertiary amino group and / or quaternary ammonium base-containing submonomer (N) unit in the polymer compound (A) used in the present invention is 0.01% by mass from the viewpoint of easy adjustment of the coating liquid. The above is preferable, and 10% by mass or less is preferable from the viewpoint of film formability. More preferably, it is 0.1-5 mass%.
Furthermore, from the viewpoint of the degree of fading that occurs when the printed matter is exposed to sunlight or fluorescent light, it is more preferable to use a quaternary ammonium base-containing submonomer (N) than a tertiary amino group-containing monomer. preferable.
Furthermore, the inclusion of both a tertiary amino group and / or quaternary ammonium base-containing monomer and the anion group-containing monomer is due to the ease of preparation of the coating liquid described above and the polymer emulsion of the present invention. From the viewpoint of both the film formability of the resulting coating layer, it is particularly preferable that the anion group-containing monomer is a carboxylic acid group-containing monomer such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and maleic acid. .

The glass transition point of the polymer compound (A) used in the present invention is preferably 50 to 150 ° C. from the viewpoint of productivity of the recording medium, and more preferably a temperature equal to or higher than the surface temperature of the mirror-finished solid (cast drum).
In producing the polymer emulsion of the present invention, the polymerization reaction is preferably performed in a temperature range exceeding the temperature sensitive point of the polymer compound (A). Since the polymer compound (A) exhibits hydrophobicity and forms an emulsion in the temperature region, the polymer emulsion of the present invention can be obtained by using a widely known polymer emulsion production technique in the temperature region. It is done. Specifically, a surfactant is dissolved in water, and the copolymerization monomer component such as the main monomer (M) and the submonomer (N) is added and emulsified, and a radical polymerization initiator is added and emulsified by a reaction by batch charging. In addition to the method of performing polymerization, there may be mentioned a method of supplying the above-mentioned copolymerization component or radical polymerization initiator to the reaction system by a method such as continuous dropping or divided addition.

In order to produce a polymer emulsion containing the polymer compound (A) used in the present invention, it is preferable to use a surfactant.
The polymer emulsion of the present invention may be anionic, cationic, nonionic or amphoteric.
When the polymer emulsion containing the polymer compound (A) is anionic, an anionic surfactant and / or a nonionic surfactant is used. For example, fatty acid soap, alkyl sulfonate, alkyl sulfosuccinate, polyoxyethylene alkyl sulfate, polyoxyethylene alkyl aryl sulfate, p-styrene sulfonate, alkyl naphthalene sulfonate, naphthalene sulfonate, formalin heavy Condensate, higher fatty acid and amino acid condensate, dialkylsulfosuccinate ester salt, naphthenate salt, alkyl ether carboxylate, acylated peptide, α-olefin sulfonate, N-acylmethyl taurine, alkyl ether sulfate, Anionic surfactants such as secondary higher alcohol ethoxy sulfates, polyoxyethylene alkylphenyl ether sulfates, monoglyculates, alkyl ether phosphate salts, alkyl phosphate salts and the like can be mentioned. Examples of the nonionic surfactant include polyoxyethylene alkyl aryl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene sorbitan fatty acid ester, oxyethylene oxypropylene block copolymer, polyglycerin fatty acid ester and the like.

  Further, when the polymer emulsion containing the polymer compound (A) is cationic, a cationic surfactant and / or a nonionic surfactant is used. For example, examples of the cationic surfactant include laurylamine hydrochloride, alkylbenzyldimethylammonium chloride, lauryltrimethylammonium chloride, alkylammonium hydroxide, and polyoxyethylene alkylamine. Nonionic surfactants include Examples thereof include polyoxyethylene alkyl aryl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene sorbitan fatty acid ester, oxyethylene oxypropylene block copolymer, polyglycerin fatty acid ester and the like.

  When the polymer emulsion containing the polymer compound (A) is nonionic, a nonionic surfactant is used. Examples of the nonionic surfactant include polyoxyethylene alkyl aryl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene sorbitan fatty acid ester, oxyethylene oxypropylene block copolymer, polyglycerin fatty acid ester and the like.

When the polymer emulsion containing the polymer compound (A) is amphoteric, it is preferable to use an amphoteric surfactant from the viewpoint of stability against changes in pH of the polymer emulsion. When the polymer emulsion is cationic, a cationic surfactant can be used. When the polymer emulsion is anionic in the coating liquid of the present invention, a cationic surfactant is used. Can be used. Examples of amphoteric surfactants include carboxybetaine type, aminocarboxylate, and lecithin.
The amount of these surfactants used is preferably 0.05 to 50 parts by weight, more preferably 1 to 100 parts by weight with respect to 100 parts by weight of the resin solid content of the polymer emulsion containing the polymer compound (A). 30 parts by mass.

In this invention, the said surfactant can also be used individually by 1 type, and can also use 2 or more types together.
By using a “surfactant having a reactive group” during polymerization of a polymer emulsion containing the polymer compound (A) of the present invention, the amount of non-reactive surfactant used can be reduced in the resulting recording medium. This is preferable from the viewpoint of water resistance of the printed image. The surfactant having a reactive group is generally called a reactive surfactant, and examples thereof include a compound having a hydrophobic group, a hydrophilic group and a reactive group in the molecule. Examples of the reactive group include carbon-carbon double bonds such as (meth) allyl group, 1-propenyl group, 2-methyl-1-propenyl group, isopropenyl group, vinyl group and (meth) acryloyl group. The functional group which has is mentioned.

  Examples of the reactive surfactant having an anionic property include those having a structure such as a sulfonate group, a sulfate ester base, a carboxylate group, and a phosphate group. Examples of vinyl monomers having a sulfonate group include allyl sulfone. Acid, 2-methylallylsulfonic acid, vinylsulfonic acid, 4-vinylbenzenesulfonic acid, 2- (meth) acryloyloxyethanesulfonic acid, 3- (meth) acryloyloxypropanesulfonic acid, 2-acrylamido-2-methylpropane Examples thereof include those obtained by neutralizing various sulfonic acid group-containing vinyl monomers such as sulfonic acid with various basic compounds. Examples of the basic compound include lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, methylamine, ethylamine, n-butylamine, dimethylamine, diethylamine, trimethylamine, triethylamine, tri-n-butylamine, diethanolamine, 2-dimethylamine. Aminoethyl alcohol, tetramethylammonium hydroxide, tetra-n-butylammonium hydroxide, etc. are mentioned.

Examples of the vinyl monomer containing a sulfate ester base include those obtained by neutralizing vinyl monomers containing a sulfate ester group such as sulfate of allyl alcohol with the various basic compounds. Examples of vinyl monomers containing phosphate groups include those obtained by neutralizing phosphate group-containing vinyl monomers such as mono {2- (meth) acryloyloxyethyl} acid phosphate with the various basic compounds. Can be mentioned. Examples of the reactive surfactant having an anionic property containing an allyl group (CH ₂ ═C (—R) —CH ₂ —) (where R is an alkyl group) include, for example, sulfuric acid of polyoxyethylene allyl glycidyl nonyl phenyl ether Examples of commercially available products include “Adekaria Soap SE-10N” series (trademark: manufactured by Asahi Denka Kogyo Co., Ltd.), “Eleminol JS-2” (trademark: manufactured by Sanyo Chemical Industries, Ltd.). "Latemul S-180 or S-180A" (trademark: manufactured by Kao Corporation), "H3390A" and "H3390B" (trademark: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and the like.

As the reactive surfactant having an anionic property containing a (meth) acryloyl group (CH ₂ ═C (—R) —C (═O) —O—) (where R is an alkyl group), for example, a commercially available product Examples thereof include “Eleminol RS-30” series (trademark: manufactured by Sanyo Chemical Industries, Ltd.), “Antox, MS-60” series (trademark: manufactured by Nippon Emulsifier Co., Ltd.), and the like. Examples of the reactive surfactant having an anionic property containing a propenyl group (CH ₃ —CH═CH—) include ammonium sulfate ester of polyoxyethylene nonylpropenyl phenyl ether, and commercially available products include “ There are Aqualon HS-10 "series and Aqualon BC series (trademark: Daiichi Kogyo Seiyaku Co., Ltd.).

  Examples of the reactive surfactant having a cationic property include cationic vinyl monomers containing a structure having a cationic property such as an amine base. Examples of vinyl monomers having an amine base include neutralizing amino group-containing vinyl monomers such as allylamine, N, N-dimethylallylamine, N, N-diethylallylamine, and N, N-diethylaminopropyl vinyl ether with various acidic compounds. What can be obtained by this. Examples of the acidic compound include hydrochloric acid, formic acid, acetic acid, lauric acid and the like. Examples of commercially available reactive surfactants having cationic properties include "RF-751" (trademark: manufactured by Nippon Emulsifier Co., Ltd.) and "Blemmer QA" (trademark: manufactured by Nippon Oil & Fats Co., Ltd.).

Examples of nonionic reactive surfactants include various polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene higher fatty acid esters, and polyoxyethylene-polyoxypropylene block copolymers. Examples thereof include vinyl ethers having an ether chain in the side chain, monomers of allyl ethers or (meth) acrylic acid esters. Examples of the nonionic reactive surfactant containing an allyl group (CH ₂ ═C (—R) —CH ₂ —) (where R is an alkyl group) include polyoxyethylene allyl glycidyl nonyl phenyl ether. Examples of commercially available products include the “ADEKA rear soap NE” series (Asahi Denka Co., Ltd.). As a nonionic reactive surfactant containing a (meth) acryloyl group (CH ₂ ═C (—R) —C (═O) —O—) (where R is an alkyl group), as a commercially available product, “ RMA-560 "series (manufactured by Nippon Emulsifier Co., Ltd.)," Blenmer PE "series (manufactured by Nippon Oil & Fats Co., Ltd.) and the like. Examples of the nonionic reactive surfactant containing a propenyl group (CH ₃ —CH═CH—) include polyoxyethylene nonylpropenyl phenyl ether, and commercially available products include “AQUALON RN series” (No. Ichi Kogyo Seiyaku Co., Ltd.).
The amount of these reactive surfactants used is preferably 0.05 to 100 parts by weight, more preferably 1 with respect to 100 parts by weight of the solid content of the polymer emulsion resin containing the polymer compound (A). -50 mass parts.

In the present invention, the reactive surfactant can be used alone, or two or more of the reactive surfactants can be used together. Further, the reactive surfactant is used in combination with the surfactant having no reactivity. You can also
When the polymer emulsion of the present invention is used in the production of an ink jet recording medium, the use of a dye ink having an anionic group in ink jet recording is often more durable than a dye ink having a cationic group. preferable. For this reason, it is preferable to add a cationic compound such as a cationic polymer or cationic particles to the coating liquid for inkjet recording media for the purpose of fixing the dye ink having the anionic group. From the viewpoint, it is more preferable to use a cationic surfactant or a nonionic surfactant in the polymer emulsion containing the polymer compound (A). In particular, when particles having a main component of silica (silicon oxide) such as dry silica and a cationic polymer are used as the coating liquid, the polymer compound (A) is used from the viewpoint of ease of preparation of the coating liquid. It is preferable that the polymer emulsion containing contains a cationic surfactant. The reason for this is not clear, but when the polymer emulsion of the present invention contains only a nonionic surfactant, fine particles mainly composed of silica are aggregated, and the adjustment of the coating liquid is not easy. It has been found that the inclusion of the cationic surfactant makes it difficult to form aggregates.

  The average particle size of the polymer emulsion particles of the present invention is not particularly limited, but is preferably 10 to 200 nm, more preferably 10 to 100 nm, from the viewpoint of the film forming property of the coating layer and the production efficiency of the polymer emulsion. It is. When the polymer emulsion of the present invention is used in the production of an ink jet recording medium, it is particularly preferably 100 nm or less from the viewpoint of transparency and color developability of the coating layer. The average particle size referred to here is the number average particle size of the polymer emulsion measured by the dynamic light scattering method in the temperature range where the polymer compound (A) exhibits hydrophobicity.

  In the coating liquid before coating, it is preferable from the viewpoint of film formability that the polymer emulsion is formed by the core portion composed of the particles (B) and the shell portion containing the polymer compound (A). . The particles (B) forming the core part may be organic polymer compounds or inorganic fine particles. From the viewpoint of flexibility of the finally obtained coating film, the organic polymer compound is More preferably, inorganic fine particles are more preferable from the viewpoint of the size of the void volume of the finally obtained coating film, ink absorbability, and the like.

The polymer emulsion formed by the core part composed of the particles (B) and the shell part containing the polymer compound (A) around the core part is composed of the particles (B) as the core part in the first stage. Manufactured by reaction similar to the method for synthesizing the polymer emulsion containing the polymer compound (A) described above after synthesis by reaction or after preparing separately prepared core (B) particles in the reaction system. can do. In the present invention, the particle (B) may be anionic, cationic, nonionic, or amphoteric, but it is more preferable that the polymer compound (A) is cationic as described above. Therefore, when polymerizing a polymer emulsion containing the polymer compound (A) in the shell portion, the particles (B) are more preferably cationic from the viewpoint of polymerization stability.

The ratio (core / shell ratio (mass ratio)) between the core portion composed of the particles (B) and the shell portion containing the polymer compound (A) around the core portion is not particularly limited. The range of 1/10 to 10/1 is preferable from the viewpoint of the coating film strength and ink absorbability of the coating layer to be obtained.
When the particle (B) is an organic polymer compound, for example, conventionally known poly (meth) acrylate-based, polyvinyl acetate-based, vinyl acetate-acrylic obtained by radical polymerization, anionic polymerization, cationic polymerization, etc. in an aqueous medium. , Ethylene vinyl acetate, silicone, polybutadiene, styrene butadiene, NBR, polyvinyl chloride, chlorinated polypropylene, polyethylene, polystyrene, vinylidene chloride, polystyrene- (meth) acrylate, styrene Copolymers such as maleic anhydride, three-dimensional cross-linked resins, etc., including silicone-modified acrylic, fluorine-acrylic, acrylic silicone, epoxy-acrylic, etc. Two or more kinds can be contained. Here, the (meth) acrylate type is simply a methacrylate type (or methacrylate type) or acrylate type. In particular, an organic polymer compound classified into a poly (meth) acrylate (acrylic polymer) and / or a polystyrene- (meth) acrylate (styrene-acrylic polymer) is finally obtained. It is preferably used from the viewpoints of transparency of the construction layer, light yellowing resistance, storage stability of the resulting recording medium, and the like.

  The particles (B) in the case of an organic polymer compound are preferably obtained as a polymer emulsion, and can be obtained by using a widely known polymer emulsion production technique. In addition to the method of emulsifying by adding a monomer component to be described later, emulsifying, adding a radical polymerization initiator and carrying out emulsion polymerization by a batch charging reaction, the reaction system can be added to the reaction system by methods such as continuous dripping and divided addition. The method of supplying the said copolymerization component and a radical polymerization initiator to a reaction system is mentioned.

  As a monomer (monomer (L)) for obtaining particles (B) in the case of an organic polymer compound, one or more of ethylenically unsaturated monomers can be used in combination. (Meth) acrylic acid esters, (meth) acrylamide monomers, vinyl cyanides, and the like. Examples of (meth) acrylic acid esters include (meth) alkyl groups having 1 to 18 carbon atoms. Acrylic acid alkyl ester, (meth) acrylic acid hydroxyalkyl ester having 1 to 18 carbon atoms in the alkyl part, (poly) oxyethylene (meth) acrylate having 1 to 100 ethylene oxide groups, number of propylene oxide groups Of 1 to 100 (poly) oxypropylene (meth) acrylates and 1 to 100 ethylene oxide groups Poly) oxyethylene di (meth) acrylate.

Specific examples of (meth) acrylic acid alkyl esters having 1 to 18 carbon atoms in the alkyl portion include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, and (meth) acrylic. Examples include 2-ethylhexyl acid, cyclohexyl (meth) acrylate, methyl cyclohexyl (meth) acrylate, dodecyl (meth) acrylate, and the like. Specific examples of the hydroxyalkyl ester of (meth) acrylic acid having 1 to 18 carbon atoms in the alkyl part include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, (meth) acrylic acid 2 -Hydroxycyclohexyl, dodecyl (meth) acrylate, and the like. Specific examples of the (poly) oxyethylene (meth) acrylate having 1 to 100 ethylene oxide groups include (meth) acrylic acid ethylene glycol, methoxy (meth) acrylic acid ethylene glycol, (meth) acrylic acid diethylene glycol, Examples include methoxy (meth) acrylic acid diethylene glycol, (meth) acrylic acid tetraethylene glycol, and methoxy (meth) acrylic acid tetraethylene glycol.

  Specific examples of the (poly) oxypropylene (meth) acrylate having 1 to 100 propylene oxide groups include propylene glycol (meth) acrylate, propylene glycol methoxy (meth) acrylate, and dipropylene (meth) acrylate. Examples thereof include glycol, methoxy (meth) acrylic acid dipropylene glycol, (meth) acrylic acid tetrapropylene glycol, and methoxy (meth) acrylic acid tetrapropylene glycol. Specific examples of (poly) oxyethylene di (meth) acrylate having 1 to 100 ethylene oxide groups include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, and methoxy (meth) acrylic acid. Examples include diethylene glycol and tetraethylene glycol di (meth) acrylate. Examples of (meth) acrylamide monomers include (meth) acrylamide, N-methylol (meth) acrylamide, N-butoxymethyl (meth) acrylamide, and diacetone acrylamide. Examples of vinyl cyanides include (meta) ) Acrylonitrile and the like.

  Specific examples other than the above include, for example, olefins such as ethylene, propylene and isobutylene, dienes such as butadiene, haloolefins such as vinyl chloride and vinylidene chloride, vinyl acetate, vinyl propionate, vinyl n-butyrate, and benzoate. Carboxylic acid vinyl esters such as vinyl acid, vinyl tert-butylbenzoate, vinyl pivalate, vinyl 2-ethylhexanoate, vinyl versatic acid, vinyl laurate, carboxylic acids such as isopropenyl acetate and isopropenyl propionate Isopropenyl esters, ethyl vinyl ether, isobutyl vinyl ether, vinyl ethers such as cyclohexyl vinyl ether, styrene derivatives such as styrene and methylstyrene, aromatic vinyl compounds such as vinyl toluene, allyl acetate, allyl benzoate, etc. Allyl esters such as allyl esters, allyl ethyl ether, allyl glycidyl ether, allyl phenyl ether, γ- (meth) acryloxypropyltrimethoxysilane, vinylmethyldiethoxysilane, vinylmethyldimethoxysilane, vinyldimethylethoxysilane, Vinyldimethylmethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine, 4- (meth) acryloyloxy-1,2,2,6 , 6-pentamethylpiperidine, perfluoromethyl (meth) acrylate, perfluoropropyl (meth) acrylate, perfluoropropylmethyl (meth) acrylate, vinyl pyrrolidone, trimethylolpropane tri (meth) ) Acrylate, glycidyl (meth) acrylate, 2,3-cyclohexene oxide (meth) acrylate, allyl (meth) acrylate, acid phosphooxyethyl methacrylate, 3-chloro-2-acid phosphooxypropyl methacrylate, methyl Carboxylic acid groups such as propanesulfonic acid acrylamide, divinylbenzene, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, crotonic acid, butenetricarboxylic acid, monoethyl maleate, monomethyl maleate, monoethyl itaconate, monomethyl itaconate -Containing monomers, sulfonic acid group-containing monomers such as 2-acrylamido-2-methyl-propanesulfonic acid, styrenesulfonic acid, vinylsulfonic acid, (meth) acrylsulfonic acid, N, N-dimethylaminoethyl ( Data) acrylate, N, amino group-containing monomers such as N- diethylaminoethyl (meth) acrylate. Here, (meth) acryl is a simple description of methacryl (or methacryl) or acryl.

From the viewpoint of film formability of the coating layer obtained using the polymer emulsion of the present invention, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, crotonic acid, butenetricarboxylic acid, monoethyl maleate, maleic acid Carboxylic acid group-containing monomers such as monomethyl, monoethyl itaconate and monomethyl itaconate, and sulfonic acid group-containing monomers such as 2-acrylamido-2-methyl-propanesulfonic acid, styrenesulfonic acid, vinylsulfonic acid and (meth) acrylsulfonic acid It is preferable to use an anion group-containing monomer such as carboxylic acid group-containing monomers such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid and maleic acid.

  The glass transition point of the particles (B) in the case of an organic polymer compound is not particularly limited, but the glass transition point is preferably −50 to 150 ° C. from the viewpoint of film formability, and generally to the obtained recording medium. From the viewpoint of imparting flexibility, -50 to 30 ° C is preferable. However, when the polymer emulsion of the present invention is used for the production of an ink jet recording medium, it is preferably 30 to 130 ° C. when the ink absorbability of the obtained ink jet recording medium is regarded as important. When importance is attached to the transparency of the ink absorbing layer, the glass transition point is preferably -50 to 30 ° C.

  The number average particle size of the particles (B) in the case of an organic polymer compound is not particularly limited, but those having a particle diameter of 3 to 150 nm are preferably used from the viewpoints of film forming properties of the coating layer and production efficiency of the polymer emulsion. 10 to 100 nm is more preferable. However, when the polymer emulsion of the present invention is used for the production of an ink jet recording medium, those having a thickness of 3 to 100 nm are preferably used from the viewpoints of transparency of the ink absorbing layer, color developability and production efficiency of the polymer emulsion. More preferably, it is 5-70 nm, Most preferably, it is 10-50 nm. The number average particle size referred to here is a number average particle size measured by a dynamic light scattering method.

  When the particles (B) forming the core portion are inorganic fine particles, examples of the particles (B) include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, and dioxide. Titanium, zinc oxide, zinc hydroxide, zinc sulfide, zinc carbonate, hydrotalcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, dry silica, alumina, colloidal alumina, pseudo boehmite Alumina, aluminum hydroxide, zeolite, magnesium hydroxide, and other metal oxides such as zirconium, titanium, tantalum, niobium, tin, tungsten, and metal phosphates such as aluminum, vanadium, zirconium, tungsten, etc. Some inorganic Those obtained by substituting another element or can also be used those obtained by modifying the surface by modifying with an organic material.

  Among these inorganic fine particles, one kind may be used alone, or two or more kinds may be used. In particular, it is preferable to use colloidal silica or dry silica as the particles (B). The use of colloidal silica or dry silica is preferable because good image quality can be obtained when printing on the resulting recording medium. It does not specifically limit as colloidal silica, Cationic colloidal silica obtained by methods, such as reacting polyvalent metal compounds, such as normal anionic colloidal silica and aluminum ion, is used. The dry silica is not particularly limited, but vapor phase silica synthesized by burning silicon tetrachloride with hydrogen and oxygen is preferably used. The dry method silica may be used as it is, or a surface modified with a silane coupling agent or the like.

  Further, when the polymer emulsion of the present invention is used for producing an inkjet recording medium, it is preferable to use alumina sol or pseudo boehmite-based alumina fine particles as the particles (B). By using alumina sol and pseudo boehmite-based alumina fine particles, it is possible to easily obtain a cationic polymer emulsion, improve image quality when printed on the resulting ink jet recording medium, and impart water resistance of the image. Can do.

The particles (B) forming the core part may be used as primary particles or in a state where secondary particles are formed. The particle diameter of the particles (B) forming the core portion is preferably a number average particle diameter of 200 nm or less, more preferably 100 nm or less in order to obtain a recording medium having a smooth surface. More preferably, those having a thickness of 50 nm or less are used. Furthermore, when the coating liquid of the present invention is used for the production of an inkjet recording medium, it is primary for the purpose of increasing the optical density (color density) of the printed part after printing and obtaining a gloss similar to silver salt photography. Particles (B) forming a core part having a number average particle diameter of 100 nm or less are preferably used, and more preferably 50 nm or less. The lower limit of the particle diameter of the particles (B) forming the core part is desirably a number average particle diameter of about 3 nm or more from the viewpoint of productivity.

In the recording medium coating liquid of the present invention, a pigment dispersant, a thickener, a flow regulator, an antifoaming agent, a defoaming agent, a release agent, a foaming agent, a colorant, and the like are blended as necessary. Can do.
In the present invention, it is preferable to contain a hydrophilic binder in the upper coating liquid from the viewpoint of surface gloss of the resulting coating layer, color development when printed using an ink jet printer, and the like. Binders similar to the binders for use can be used.
The addition amount of the hydrophilic binder is preferably 10% by mass or less, particularly preferably 5% by mass or less, based on the fine particles (C) described later, from the viewpoint of suppressing microcracks on the surface of the obtained recording medium.

When using polyvinyl alcohol, it is particularly preferable to use dry silica as fine particles (C) described later. Polyvinyl alcohol has a hydroxyl group in its structural unit, but this hydroxyl group and the silanol group on the surface of the silica fine particle form a hydrogen bond, and it is easy to form a three-dimensional network structure in which the secondary particle of the silica fine particle is a chain unit. To do. By forming the three-dimensional network structure, a porous structure having a high porosity can be formed, and a coating layer having good ink absorbability can be obtained. Furthermore, the thickening due to cooling immediately after coating is also improved by the formation of hydrogen bonds between the hydroxyl groups of polyvinyl alcohol and the silanol groups on the surface of the silica fine particles.
The ratio of the hydrophilic binder to the fine particles (C) is approximately 1:15 to 1: 1 by mass ratio, preferably 1:10 to 1: 2.

In order to obtain the ink jet recording medium of the present invention without deteriorating the high porosity of the coating layer, the hydrophilic binder is preferably hardened with a hardener.
The hardener is generally a compound having a group capable of reacting with the hydrophilic binder or a compound that promotes the reaction between different groups of the hydrophilic binder, and is appropriately selected depending on the type of the hydrophilic binder. Select and use.

  Specific examples of the hardener include, for example, epoxy hardeners (diglycidyl ethyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidyl cyclohexane, N, N- Diglycidyl 4-glycidyloxyaniline, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, etc.), aldehyde hardeners (formaldehyde, glioxal, etc.), active halogen hardeners (2,4-dichloro-4-hydroxy-1, 3,5-s-triazine, etc.), active vinyl compounds (1,3,5-trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether, etc.), boric acid and its salts, borax, aluminum alum, etc. Is mentioned.

When polyvinyl alcohol is used as a particularly preferred hydrophilic binder, from the viewpoint of the coating strength of the coating layer, at least one hardener selected from boric acid and its salts and / or epoxy hardeners is used. It is preferable to use it, and boric acid and / or borax are most preferable from the viewpoint of coating liquid thickening (gelation) immediately after coating.
The amount of the hardener used varies depending on the type of the hydrophilic binder, the type of the hardener, the type of inorganic fine particles, the ratio to the hydrophilic binder, and the like.
200 mg, preferably 5 to 100 mg.

  When gelatin is used as the hydrophilic binder, the following compounds known as gelatin hardeners can be used as hardeners. For example, aldehyde compounds such as formaldehyde, glyoxal and glutaraldehyde, ketone compounds such as diacetyl and cyclopentanedione, bis (2-chloroethylurea) -2-hydroxy-4,6-dichloro-1,3,5- Active halogen compounds such as triazine, 2,4-dichloro-6-S-triazine sodium salt, divinylsulfonic acid, 1,3-vinylsulfonyl-2-propanol, N, N′-ethylenebis (vinylsulfonylacetamide) ), Active vinyl compounds such as 1,3,5-triacryloyl-hexahydro-S-triazine, N-methylol compounds such as dimethylolurea and methyloldimethylhydantoin, isocyanate compounds such as 1,6-hexamethylene diisocyanate, US Patent No. 3017280 , Aziridine compounds described in U.S. Pat. No. 2,983,611, carboximide compounds described in U.S. Pat. No. 3,100,704, epoxy compounds such as glycerol triglycidyl ether, 1,6-hexamethylene-N, N Ethyleneimino compounds such as' -bisethyleneurea, halogenated carboxaldehyde compounds such as mucochloric acid and mucophenoxycyclolic acid, dioxane compounds such as 2,3-dihydroxydioxane, chromium alum, potash alum, zirconium sulfate And chromium acetate. In addition, the said hardening agent may be single 1 type, or may combine 2 or more types.

The above hardener is preferably used by dissolving the hardener in water and / or an organic solvent from the viewpoint of ease of adjustment of the coating liquid, stability, and the like. The concentration of the hardener in the hardener solution is preferably 0.05 to 20% by weight, particularly preferably 1 to 10% by weight, based on the weight of the hardener solution. As a solvent constituting the hardener solution, water is generally used, and an aqueous mixed solvent containing an organic solvent miscible with water may be used. The organic solvent can be arbitrarily used as long as it can dissolve the hardener, for example, alcohols such as methanol, ethanol, isopropyl alcohol and glycerin; ketones such as acetone and methyl ethyl ketone; methyl acetate and ethyl acetate. An ester such as toluene; an aromatic solvent such as toluene; an ether such as tetrahydrofuran; and a halogenated carbon-based solvent such as dichloromethane.
When polymerizing the polymer compound (A), polymerization in the presence of polyvinyl alcohol or a polyvinyl alcohol derivative is preferable from the viewpoints of film formability and film strength of the coating layer of the finally obtained recording medium.

  The polyvinyl alcohol and / or polyvinyl alcohol derivative used for the polymerization of the polymer compound (A) of the present invention is not particularly limited, but as the polyvinyl alcohol, polyvinyl alcohol having a saponification degree of 96% to 100% generally called fully saponified polyvinyl alcohol is used. Examples of the alcohol include polyvinyl alcohol having a saponification degree of 76% to 95%, generally called partially saponified polyvinyl alcohol. Examples of the polyvinyl alcohol derivative include silanol-modified polyvinyl alcohol, cation-modified polyvinyl alcohol, mercapto group-containing polyvinyl alcohol, and keto group. Examples thereof include polyvinyl alcohol. One kind of polyvinyl alcohol and / or polyvinyl alcohol derivative may be used, or a plurality of kinds may be mixed and used. The polymerization degree of the polyvinyl alcohol and the polyvinyl alcohol derivative is not particularly limited, but those having a polymerization degree of 300 to 4000 are preferably used.

  The use ratio of the main monomer (M) and the submonomer (N), polyvinyl alcohol and / or polyvinyl alcohol derivative is determined within the range in which the obtained polymer compound (A) exhibits temperature responsiveness. The content of polyvinyl alcohol and / or polyvinyl alcohol derivative in A) is not particularly limited within the range of the conditions, but from the viewpoint of water resistance of the coating film of the finally obtained recording medium, 50 wt% is preferably used, and more preferably 0.5 to 20 wt%.

Using a polymer emulsion containing the polymer compound (A) obtained by polymerization in the presence of polyvinyl alcohol and / or a polyvinyl alcohol derivative, the film formability and composition of the coating layer of the finally obtained recording medium From the viewpoint of film strength, it is preferable to add a crosslinking agent capable of crosslinking polyvinyl alcohol and / or polyvinyl alcohol derivative to the coating solution.
As the crosslinking agent, from the viewpoint crosslinking reaction is rapid, boron compounds are preferable, for example, borax, boric acid, borates (eg, _{orthoborate, InBO 3, ScBO 3, YBO} 3, LaBO 3, Mg ₃ (BO ₃ ) ₂ , Co ₃ (BO ₃ ) ₂ , diborate (eg, Mg ₂ B ₂ O ₅ , Co ₂ B ₂ O ₅ ), metaborate (eg, LiBO ₂ , Ca (BO ₂₎ ) ₂ , NaBO ₂ , KBO ₂ ), tetraborate (eg, Na ₂ B ₄ O ₇ .10H ₂ O), pentaborate (eg, KB ₅ O ₈ .4H ₂ O, Ca ₂ B ₆ O) ₁₁ · 7H ₂ O, CsB ₅ O ₅ ), glyoxal, melamine / formaldehyde (eg, methylolmelamine, alkylated methylolmelamine), methylolurea, resol resin, polyisocyanate, epoxy resin, etc. However, borax, boric acid, and borate are preferable in that a crosslinking reaction is quickly caused.

The amount of boric acid or its salt used is selected from a wide range depending on the concentration, pH, etc. of other components in the coating liquid, such as inorganic fine particles, polyvinyl alcohol or polyvinyl alcohol derivatives, but is approximately 1 with respect to polyvinyl alcohol. It is preferable that it is -60 mass%, and 5-40 mass% is still more preferable.
In addition to the polyvinyl alcohol or polyvinyl alcohol derivative, polyvinyl acetal, cellulose resins (methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, etc.), chitins, chitosans, starch, polyethylene oxide which is an ether bond, polypropylene Water-soluble resins such as oxide, polyethylene glycol, polyvinyl ether, amide group or polyacrylamide, polyvinyl pyrrolidone, polyacrylate, maleic acid resin, alginate, and gelatin having a amide bond can be used. Polyvinyl alcohol or polyvinyl alcohol derivatives are most preferably used.

It is preferable to add a crosslinking agent capable of crosslinking the polymer emulsion of the present invention to the recording medium coating solution from the viewpoint of coating strength and water resistance of the coating layer of the recording medium.
In particular, it is industrially desirable that the crosslinking reaction does not proceed in the coating solution before coating, but the crosslinking reaction proceeds after coating. The reaction is preferably a reaction of a carbonyl group with a hydrazine group or a semicarbazide group. That is, it is preferable to polymerize a polymer emulsion having a carbonyl group and use a hydrazine derivative having a hydrazine group and / or a semicarbazide group as a crosslinking agent.

  The carbonyl group is preferably contained in the polymer compound (A) from the viewpoint of coating film strength. The polymer compound (A) containing a carbonyl group is obtained, for example, by copolymerizing a main monomer (M) and a submonomer (N) containing a monomer containing a carbonyl group. The main monomer (M) and the submonomer (N) containing a monomer containing a carbonyl group can be used alone or in combination of two or more. The content of the carbonyl group-containing monomer unit in the polymer compound (A) is preferably from 0.01 to 50 mass%, more preferably from 0.1 to 20 mass%, from the viewpoint of film formability.

The carbonyl group-containing monomer is not particularly limited as long as it has a structure containing a keto group or an aldo group, but acrolein, diacetone acrylamide, diacetone methacrylamide, formylstyrene, vinyl methyl ketone, vinyl ethyl Examples include ketone, vinyl isobutyl ketone, acryloxyalkylpropanals, methacryloxyalkylpropanals, diacetone acrylate, diacetone methacrylate, acetonitrile acrylate, 2-hydroxypropyl acrylate acetyl acetate, butanediol acrylate acetyl acetate, and the like.

  When the polymer emulsion of the present invention contains a carbonyl group, it is possible to use a hydrazine derivative having at least two hydrazine groups and / or semicarbazide groups as a crosslinking agent in the coating liquid used for recording paper production. It is preferable from the viewpoint of the water resistance and strength of the coating film. A coating layer containing a compound having a molecular structure in which a carbonyl group site is cross-linked by a hydrazine derivative by adding, mixing, coating, and drying the hydrazine derivative to the coating solution containing the polymer emulsion of the present invention. Can be obtained. The hydrazine derivative is not particularly limited as long as it is a compound having at least two hydrazine groups and / or semicarbazide groups. Among these compounds, carbohydrazide, isophthalic acid dihydrazide, malonic acid dihydrazide, amber Acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, itaconic acid dihydrazide, polyacrylic acid hydrazide, ethylene-1,2-dihydrazine, propylene-1,3-dihydrazine, Examples include butylene-1,4-dihydrazine and hydrated hydrazine, and examples of the compound having a semicarbazide group include products obtained by the reaction of a polyisocyanate compound and the hydrazine compound. That. As the hydrazine derivative, a compound having a semicarbazide group is preferable because the resulting recording medium has high water resistance. Although content of this hydrazine derivative is not specifically limited, 0.01-10 times mole amount is preferably used with respect to the carbonyl group containing monomer unit in the obtained polymer emulsion.

  The temperature sensitive point can be lowered by adding alcohols such as ethyl alcohol to the polymer emulsion containing the polymer compound (A) of the present invention. That is, when the temperature sensitive point is room temperature or outside air temperature or higher, by adding alcohols, the polymer compound (A) can be kept in an emulsion state at a temperature below room temperature or outside air temperature. The polymer emulsion containing A) can be transported and stored very easily and economically, which is preferable. Although there is no restriction | limiting in particular as alcohol, Ethyl alcohol, methyl alcohol, n-propyl alcohol, n-butyl alcohol, isopropyl alcohol, n-pentyl alcohol, n-hexyl alcohol, ethylene glycol, propylene glycol, glycerol etc. are mentioned. However, methyl alcohol, ethyl alcohol, and isopropyl alcohol are preferably used from the viewpoint of effects. These alcohols can also be used independently and can also be used in combination of 2 or more types. In the case of ethanol, the alcohol is preferably added in an amount of usually 5 to 200 parts by mass with respect to 100 parts by mass of water in the polymer emulsion.

The coating liquid of the present invention is preferably prepared and used at a temperature exceeding the temperature sensitive point of the polymer compound (A). That is, the coating liquid has a relatively low viscosity at a temperature exceeding the temperature sensitive point, but when the coating liquid is cooled to a temperature below the temperature sensitive point, the coating liquid rapidly increases in viscosity. (Or gelation).
The inclusion of fine particles (C) in the coating liquid of the present invention is preferable from the viewpoint of ink absorbability of the resulting recording medium. The fine particles (C) may be organic compounds or inorganic compounds.

When the fine particles (C) are organic compounds, for example, conventionally known poly (meth) acrylates, polyvinyl acetates, vinyl acetate-acrylics obtained by radical polymerization, anion polymerization, cationic polymerization in an aqueous medium, Ethylene vinyl acetate, silicone, polybutadiene, styrene butadiene, NBR, polyvinyl chloride, chlorinated polypropylene, polyethylene, polystyrene, vinylidene chloride, polystyrene- (meth) acrylate, styrene-anhydrous malee Examples include acid-based copolymers, three-dimensional crosslinked resins, and silicone-modified acrylic, fluorine-acrylic, acrylic silicone, and epoxy-acrylic modified copolymers. The above can be contained. Here, the (meth) acrylate type is simply a methacrylate type (or methacrylate type) or acrylate type. In particular, an ink in which an organic polymer compound classified into a poly (meth) acrylate (acrylic polymer) and / or a polystyrene- (meth) acrylate (styrene-acrylic polymer) is finally obtained. It is preferably used from the viewpoints of transparency of the absorbing layer, light yellowing resistance, storage stability of the resulting recording medium, and the like.

  The fine particles (C) in the case of an organic polymer compound are preferably obtained as a polymer emulsion, and can be obtained by using a widely known polymer emulsion production technique. In addition to the method of emulsifying by adding a monomer component to be described later, emulsifying, adding a radical polymerization initiator and carrying out emulsion polymerization by a batch charging reaction, the reaction system can be added to the reaction system by methods such as continuous dripping and divided addition. The method of supplying the said copolymerization component and a radical polymerization initiator to a reaction system is mentioned.

  As the monomer for obtaining fine particles (C) in the case of an organic polymer compound, one or more of ethylenically unsaturated monomers can be used in combination. Specifically, (meth) Acrylic acid esters, (meth) acrylamide monomers, vinyl cyanides and the like. Examples of (meth) acrylic acid esters include (meth) acrylic acid alkyl esters having 1 to 18 carbon atoms in the alkyl portion, alkyls (Meth) acrylic acid hydroxyalkyl ester having 1 to 18 carbon atoms, (poly) oxyethylene (meth) acrylate having 1 to 100 ethylene oxide groups, and 1 to 100 propylene oxide groups (Poly) oxypropylene (meth) acrylate, (poly) oxye having 1 to 100 ethylene oxide groups Di (meth) acrylate. Specific examples of (meth) acrylic acid alkyl ester having 1 to 18 carbon atoms in the alkyl part include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, and (meth) acrylic. Examples include 2-ethylhexyl acid, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, dodecyl (meth) acrylate, and the like.

  Specific examples of the hydroxyalkyl ester of (meth) acrylic acid having 1 to 18 carbon atoms in the alkyl portion include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, (meth) acrylic acid 2 -Hydroxycyclohexyl, dodecyl (meth) acrylate, and the like. Specific examples of the (poly) oxyethylene (meth) acrylate having 1 to 100 ethylene oxide groups include (meth) acrylic acid ethylene glycol, methoxy (meth) acrylic acid ethylene glycol, (meth) acrylic acid diethylene glycol, Examples include methoxy (meth) acrylic acid diethylene glycol, (meth) acrylic acid tetraethylene glycol, and methoxy (meth) acrylic acid tetraethylene glycol. Specific examples of the (poly) oxypropylene (meth) acrylate having 1 to 100 propylene oxide groups include propylene glycol (meth) acrylate, propylene glycol methoxy (meth) acrylate, and dipropylene (meth) acrylate. Examples thereof include glycol, methoxy (meth) acrylic acid dipropylene glycol, (meth) acrylic acid tetrapropylene glycol, and methoxy (meth) acrylic acid tetrapropylene glycol.

Specific examples of (poly) oxyethylene di (meth) acrylate having 1 to 100 ethylene oxide groups include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, and methoxy (meth) acrylic acid. Examples include diethylene glycol and tetraethylene glycol di (meth) acrylate. Examples of (meth) acrylamide monomers include (meth) acrylamide, N-methylol (meth) acrylamide, N-butoxymethyl (meth) acrylamide, and diacetone acrylamide. Examples of vinyl cyanides include (meta) ) Acrylonitrile and the like.

  Specific examples other than the above include, for example, olefins such as ethylene, propylene and isobutylene, dienes such as butadiene, haloolefins such as vinyl chloride and vinylidene chloride, vinyl acetate, vinyl propionate, vinyl n-butyrate, Carboxylic acid vinyl esters such as vinyl benzoate, p-t-butyl vinyl benzoate, vinyl pivalate, vinyl 2-ethylhexanoate, vinyl versatate, vinyl laurate, etc. Carboxyl such as isopropenyl acetate and isopropenyl propionate Acid isopropenyl esters, ethyl vinyl ether, isobutyl vinyl ether, vinyl ethers such as cyclohexyl vinyl ether, styrene derivatives such as styrene and methyl styrene, aromatic vinyl compounds such as vinyl toluene, allyl acetate, allyl benzoate Allyl esters, allyl ethyl ether, allyl glycidyl ether, allyl phenyl ether and other allyl ethers, γ- (meth) acryloxypropyltrimethoxysilane, vinylmethyldiethoxysilane, vinylmethyldimethoxysilane, vinyldimethylethoxysilane , Vinyldimethylmethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine, 4- (meth) acryloyloxy-1,2,2, 6,6-pentamethylpiperidine, perfluoromethyl (meth) acrylate, perfluoropropyl (meth) acrylate, perfluoropropylmethyl (meth) acrylate, vinyl pyrrolidone, trimethylolpropane tri (me Acrylate), glycidyl (meth) acrylate, 2,3-cyclohexene oxide (meth) acrylate, allyl (meth) acrylate, acid phosphooxyethyl methacrylate, 3-chloro-2-acid phosphooxypropyl methacrylate, Examples include methyl propane sulfonic acid acrylamide and divinyl benzene. Here, (meth) acryl is a simple description of methacryl (or methacryl) or acryl.

The glass transition point of the fine particles (C) in the case of an organic polymer compound is preferably from 50 to 150 ° C, more preferably from 90 to 150 ° C, from the viewpoint of ink absorbability of the recording paper to be obtained.
When the fine particles (C) are inorganic compounds, for example, light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc hydroxide, zinc sulfide, Zinc carbonate, hydrotalcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, dry silica, alumina, colloidal alumina, pseudo boehmite alumina, aluminum hydroxide, zeolite, magnesium hydroxide, Other examples include metal oxides such as zirconium, titanium, tantalum, niobium, tin, and tungsten, and metal phosphates such as aluminum, vanadium, zirconium, and tungsten. A part of the inorganic compound is substituted with another element. Things or organic It can also be used in those who modify the surface by modifying. Among these inorganic fine particles, one type may be used alone, or two or more types may be used.

In particular, it is preferable to use colloidal silica, dry silica, alumina sol, or pseudo boehmite-based alumina as the fine particles (C). Especially when used for an ink jet recording medium, from the viewpoint of ink absorbability, dry silica and pseudo-boehmite alumina are preferable. preferable. By using colloidal silica or dry silica, the image quality when printed on the resulting recording medium is improved, and gloss can be imparted. As the colloidal silica, anionic colloidal silica, cationic colloidal silica obtained by a method of reacting a polyvalent metal compound such as aluminum ion, or a material whose surface is modified with a silane coupling agent is preferably used. As dry silica, vapor phase silica synthesized by burning silicon tetrachloride with hydrogen and oxygen is preferably used. The dry silica may be used as it is, but from the viewpoints of easy adjustment of the coating solution and stability of the coating solution viscosity over time, a product whose surface is modified with a silane coupling agent is preferably used. Those modified with a silane coupling agent having a group are more preferably used.
Also, by using alumina sol and pseudo boehmite-based alumina fine particles, a recording paper with higher gloss can be easily obtained, image quality when printed on a recording medium can be improved, and water resistance of the image can be imparted. .

  The fine particles (C) used in the present invention may be used as primary particles or in a state in which secondary particles are formed. Any particle size of the fine particles (C) can be used. In order to obtain a recording medium having a smooth surface, those having a number average particle size of 10 μm or less are usually used, preferably 1 μm or less. Things are used. Furthermore, when manufacturing an inkjet recording medium, the number average particle diameter of primary particles is 200 nm or less for the purpose of increasing the optical density (color density) of the printed part after printing and obtaining gloss similar to that of a silver salt photograph. The fine particles (C) are preferably used, more preferably those having a number average particle size of 100 nm or less, and still more preferably 50 nm or less.

Although the minimum of the particle diameter of microparticles | fine-particles (C) is not specifically limited, From a viewpoint of the manufacture efficiency of microparticles | fine-particles (C), it is desirable that it is a number average particle diameter of about 3 nm or more.
Furthermore, as the fine particles (C), a porous material produced through a process of producing a composite by using a metal oxide and / or a precursor thereof as a metal source and mixing and reacting the metal source, template and water is used. This is preferable from the viewpoint of ink absorbability of the resulting coating layer. And (a) a step of producing a composite by using a metal oxide and / or a precursor thereof as a metal source as the fine particles (C), and (a) the composite. The difference between the converted specific surface area SL obtained from the number average particle diameter DL measured by the dynamic light scattering method and the nitrogen adsorption specific surface area SB by the BET method (SB-SL) ) Is more preferably 250 m ² / g or more from the viewpoint of ink absorbability of the resulting coating layer. Here, “porous” means having pores in the pore distribution determined by the nitrogen adsorption method. The converted specific surface area SL (m ² / g) calculated from the average particle diameter DL measured by the dynamic light scattering method assumes that the particles are spherical, and SL = 6 × 10 ³ / (density (g / cm ³ ) × DL (nm)). The difference between this value and the nitrogen adsorption specific surface area SB by the BET method (SB-SL) is 250 m ² / g or more indicates that the particles are extremely porous. It is particularly preferable to use the ink jet recording medium from the viewpoint of ink absorbability.

In order to obtain a recording medium having a smooth surface, the porous material usually has a DL of 10 μm or less, preferably 1 μm or less. Furthermore, in the production of an inkjet recording medium, fine particles (C) having a DL of 300 nm or less for the purpose of increasing the optical density (color density) of the printed portion after printing and obtaining a gloss similar to silver salt photography. Is preferably used, and more preferably 150 nm or less.
The lower limit of the particle size of the porous material is preferably a number average particle size of about 10 nm or more from the viewpoint of production efficiency of the porous material.

  The metal source used in the synthesis of the porous material is a metal oxide and / or a precursor thereof, and as the metal species, silicon, an alkaline earth metal such as group 2 magnesium or calcium, zinc, group 3 aluminum Gallium, rare earth, etc., Group 4 titanium, zirconium, etc., Group 5 phosphorus, vanadium, Group 7 manganese, tellurium, etc., Group 8 iron, cobalt and the like. Examples of the precursor include inorganic salts such as nitrates and hydrochlorides of these metals, organic acid salts such as acetates and naphthenates, organic metal salts such as alkylaluminums, alkoxides and hydroxides.

When silicon is selected as the metal, an alkoxide such as tetraethoxysilane or activated silica can be preferably used as the metal source. The active silica can be prepared by extraction from water glass with an organic solvent or ion exchange of the water glass. Use of inexpensive water glass as a raw material is preferable from the viewpoint of industrial use. In particular, when water glass is prepared by contacting with an H ⁺ type cation exchanger, it is industrially preferable to use No. 3 water glass, which has a low Na content and is inexpensive. As the cation exchanger, for example, a sulfonated polystyrene divinylbenzene-based strongly acidic exchange resin (for example, Amberlite IR-120B: trade name, manufactured by Rohm & Haas) is preferable.

When aluminum is selected as the metal, an alkali aluminate, specifically sodium aluminate, potassium aluminate, lithium aluminate, primary ammonium aluminate, guanidine aluminate, or the like can be used as the metal source.
As the template, one having an interaction with a compound serving as a metal source is used. When a nonionic surfactant is used, when producing the porous material, water or water is used in the template removal step described later. The template can be easily removed using a mixed solvent of organic solvents, which is preferable.

Examples of the nonionic surfactant, the structural formula _{HO (C 2 H 4 O)} a - (C 3 H 6 O) b - (C 2 H 4 O) c H ( where, a, c are the 10 to 110 , B represents 30 to 70), or a structural formula R (OCH ₂ CH ₂ ) _n OH (where R represents an alkyl group having 12 to 20 carbon atoms, and n represents 2 to 30). ) Is preferred. Specifically, “Pluronic P103”, “Pluronic P123”, “Pluronic P85” (manufactured by Asahi Denka Kogyo Co., Ltd., surfactant: trade name), polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, poly Examples thereof include oxyethylene stearyl ether.
In order to change the pore diameter of the porous material, as an organic auxiliary, an aromatic hydrocarbon having 6 to 20 carbon atoms, an alicyclic hydrocarbon having 5 to 20 carbon atoms, an aliphatic carbonization having 3 to 16 carbon atoms Hydrogen and their amines and halogen substituents such as toluene, trimethylbenzene, triisopropylbenzene and the like can be added.

Below, the manufacturing method of this porous substance is demonstrated.
The reaction between the metal source and the template can be carried out, for example, after stirring and mixing the metal source dissolved or dispersed in the solvent and the template dissolved or dispersed in the solvent, but is not limited thereto. Absent. As the solvent, either water or a mixed solvent of water and an organic solvent may be used, and as the organic solvent, alcohols are preferable. As alcohols, lower alcohols such as ethanol and methanol are preferred.

  The composition of the raw materials used in these reactions varies depending on the template, the metal source, and the solvent, but it is necessary to select a range in which aggregation, precipitation, etc. occur and the particle diameter does not increase. In order to prevent aggregation and precipitation of particles, an alkali such as NaOH or a stabilizer such as low molecular weight polyvinyl alcohol may be added.

For example, when using active silica as the metal source, “Pluronic P103” as the template, and water as the solvent, the following composition can be used. The mass ratio of P103 / SiO ₂ is preferably 0.01 to 30, more preferably 0.1 to 5. The mass ratio of organic assistant / P103 is preferably 0.02 to 100, more preferably 0.05 to 35. The mass ratio of water / P103 during the reaction is preferably in the range of 10 to 1000, more preferably 20 to 500. As a stabilizer, NaOH may be added in a range of 1 × 10 ^{−4 to} 0.15 as a mass ratio of NaOH / SiO ₂ .

When the porous material contains silicon and aluminum, the element ratio of Al / Si is preferably 0.003 to 0.1, and more preferably 0.005 to 0.05.
Although the reaction proceeds easily even at room temperature, it can be carried out under heating up to 100 ° C., if necessary. The reaction time is 0.5 to 100 hours, preferably 3 to 50 hours. The pH during the reaction is preferably in the range of 2 to 13, more preferably 4 to 12, and an alkali such as NaOH or an acid such as hydrochloric acid or sulfuric acid may be added to control the pH.

  After the production of the composite, a step of denaturing by heating to 40 to 95 ° C. in the presence of alkali aluminate can also be performed. When the composite contains silicon, a sol that is stable even when acidified or added with a cationic substance and can withstand long-term storage can be produced by performing this step. As the alkali aluminate to be used, sodium aluminate, potassium aluminate, lithium aluminate, ammonium ammonium aluminate, guanidine aluminate and the like can be used, and sodium aluminate is preferable. The denaturing step may be performed before or after removing the template from the complex.

Hereinafter, the modification method will be described taking the case before the template removal as an example.
After producing the composite, an alkali aluminate solution is added to the reaction solution. The addition is performed with stirring at 0-80 ° C, preferably 5-40 ° C. Although the density | concentration of the aluminate alkali to add is not specifically limited, It is preferable to use at 1-20 mass%. The amount to be added is preferably 0.003 to 0.1, more preferably 0.005 to 0.05, as an element ratio of Al / Si. It is preferable to heat at 40-95 degreeC after addition, and it is more preferable to heat at 60-80 degreeC. Heating at 40 ° C. or lower tends to gel when the sol is made and is made acidic, and sufficient stability cannot be obtained.

Next, a template removal method will be described.
A porous material is obtained by adding a solvent such as alcohol to the obtained reaction solution and removing the template from the composite using an ultrafiltration device or the like. At this time, an alkali such as NaOH or a stabilizer such as low molecular weight polyvinyl alcohol may be added to prevent aggregation of particles. The solvent used for removal is not particularly limited as long as it dissolves the template, and alcohols that are easy to handle and have high dissolving power are preferable. As alcohols, lower alcohols such as methanol and ethanol are preferred. The removal temperature varies depending on the solvent and template used, but is preferably 20 to 80 ° C. The removed template can be reused by removing the solvent. Further, the obtained composite is separated by filtration, washed with water, dried, and then the contained template is contacted with a solvent such as a supercritical fluid or alcohol, or removed by a method such as baking. A porous material may be obtained. The baking temperature is not less than the temperature at which the template disappears, and generally not less than 500 ° C. The firing time is appropriately set in relation to the temperature, but is about 30 minutes to 6 hours. As a removing method, a method of stirring and mixing the solvent and the composite, a method of filling the composite in a column or the like and circulating the solvent can be used.

  Further, the fine particles (C) used in the present invention are selected from a dispersion or suspension containing silica seed particles surface-treated with a hydrophobic silane coupling agent, and an aqueous solution of active silicic acid and alkoxysilane in the presence of alkali. It is obtained by wet pulverizing a silica fine particle aggregate dispersion obtained by growing each silica primary particle constituting the silica seed particles by adding at least one of the above, using a known disperser such as an ultra-high pressure homogenizer. Are also preferred.

In the present invention, when producing an inkjet recording medium, it is preferable that at least one of the ink absorbing layers contains a cationic polymer (D). By containing the cationic polymer (D), the water resistance of the printed portion is improved. As the cationic polymer (D), any cationic polymer can be used as long as it exhibits a cationic property, but at least of primary amine, secondary amine, tertiary amine substituents and salts thereof, and quaternary ammonium salt substituents. Those containing one kind are preferably used. Examples thereof include dimethyldiallylammonium chloride polymer, dimethyldiallylammonium chloride-acrylamide copolymer, alkylamine polymer, polyamine dicyan polymer, and polyallylamine hydrochloride. The cationic polymer (D) preferably has a weight average molecular weight of 1,000 to 200,000. The amount of the cationic polymer (D) used is preferably from 0.1 to 200 parts by weight, more preferably from 1 to 100 parts by weight, still more preferably from 100 parts by weight of the polymer emulsion, from the viewpoint of the water resistance of the coating film. Is 5 to 20 parts by mass. Furthermore, it is preferable to use a cationic polymer (D) having only a quaternary ammonium substituent from the viewpoint of the degree of fading that occurs when the printed material is exposed to sunlight or fluorescent light.

  In the present invention, when producing an inkjet recording medium, at least one of the coating layers contains one or more of an ultraviolet absorber, a hindered amine light stabilizer, a singlet oxygen quencher, an antioxidant, and the like. It is preferable. By containing this substance, the light resistance of the printed part is improved. Although it does not specifically limit as an ultraviolet absorber, A benzotriazole type | system | group, a benzophenone type | system | group, a titanium oxide, a cerium oxide, a zinc oxide etc. are used preferably. Although it does not specifically limit as a hindered amine light stabilizer, N atom of a piperidine ring is NR (R is a hydrogen atom, an alkyl group, a benzyl group, an allyl group, an acetyl group, an alkoxyl group, a cyclohexyl group, a benzyloxy group, etc.). Some are preferably used. As the singlet oxygen quencher, an aniline derivative, an organic nickel series, a spirochroman series, or a spiroindane series is preferably used. As the antioxidant, phenol, hydroquinone, organic sulfur, phosphorus, and amine are preferably used. The amount of the substance used is preferably 0.0001 to 5 parts by mass with respect to 100 parts by mass of the ink absorption layer in the ink absorption layer containing the substance.

  In the present invention, when producing an inkjet recording medium, it is preferable that at least one of the ink absorbing layers contains an alkaline earth metal compound. Light resistance improves by containing an alkaline-earth metal compound. As the alkaline earth metal compound, oxides, halides and hydroxides of magnesium, calcium and barium are preferably used. As a method of incorporating an alkaline earth metal compound into the ink absorption layer, it may be added to the coating liquid, or after forming the ink absorption layer, the ink absorption layer is impregnated with an aqueous solution of an alkaline earth metal compound. May be. The content of the alkaline earth metal compound is preferably 0.5 to 5 parts by mass in terms of oxide with respect to 100 parts by mass of the solid content in the ink absorption layer in the ink absorption layer containing the alkaline earth metal compound. .

  In the present invention, it is preferable that the coating layer contains a thiocyanic acid compound because ozone resistance and light resistance can be improved. Examples of the thiocyanate compound include ammonium thiocyanate, zinc thiocyanate, calcium thiocyanate, potassium thiocyanate, sodium thiocyanate, magnesium thiocyanate, aluminum thiocyanate, lithium thiocyanate, silver thiocyanate, chloromethyl thiocyanate, and thiocyanate. Cobalt, copper thiocyanate, lead thiocyanate, barium thiocyanate, benzyl thiocyanate, and the like, and ammonium thiocyanate, zinc thiocyanate, and calcium thiocyanate are preferable in terms of further improving ozone resistance and light resistance. Particularly preferred are ammonium acid and zinc thiocyanate.

  As content of said thiocyanic acid compound, 0.3-10 mass% is preferable with respect to the total solid of a coating layer, and 0.5-8 mass% is further more preferable. When the content is in the range of 0.3 to 10% by mass, it is preferable in terms of ozone resistance, water resistance, and aging blur (a phenomenon in which bleeding occurs due to the printing portion being passed for a long time). Moreover, the said thiocyanic acid compound may be used individually by 1 type, and may use 2 or more types together.

The upper layer coating solution of the present invention has a solubility parameter (hereinafter referred to as SP value) of 10 to 13 (cal / cm ³ ) ^1/2 , more preferably 10.5 to 11.5 (cal / cm ^3). It is preferable to contain a high boiling point solvent having a vapor pressure of ^1/2 at 20 ° C. of 40 mmHg or less in order to suppress partial drying of the coating liquid. The content of the high boiling point solvent is preferably 50 to 500 parts by mass, more preferably 100 to 200 parts by mass with respect to 100 parts by mass of the polymer emulsion. When the content is large, the coating liquid is likely to be aggregated, and when it is 5 parts by mass or less, there is no effect of suppressing partial drying.

As the high boiling point solvent, alcohols are preferable from the viewpoints of safety and handling, and isopropyl alcohol (SP value 11.5, vapor pressure 32 mmHg), 1-butyl alcohol (SP value 11.4, vapor pressure 4. 4 mmHg), 2-butyl alcohol (SP value 11.1, vapor pressure 12.7 mmHg), isobutyl alcohol (SP value 11.0, vapor pressure 8 mmHg), 1-pentanol (SP value 10.6, vapor pressure 4) 0.0 mmHg) is more preferable.
Solvents other than those described above may be added to the recording medium coating solution of the present invention. Although a solvent is not specifically limited, Water-soluble solvents, such as alcohol, a ketone, and ester, and / or water are used preferably.

Lower coating liquid of the present invention, the solid content concentration was adjusted to about 5 to 65 wt%, 1 to 30 g / m ² dry weight on the support of the above, preferably 2 to 20 g / m ² It is obtained by coating and drying with various publicly known coating apparatuses such as a blade coater, an air knife coater, a roll coater, a brush coater, a chamber coater, a bar coater, and a gravure coater. Furthermore, if necessary, after the recording layer is dried, a smoothing process such as super calendering or brushing can be performed.

  Moreover, it is preferable to contain the above-mentioned cationic polymer (D) in a lower layer coating liquid. By containing the cationic polymer (D), the water resistance of the printed portion is improved. The content of the cationic polymer (D) is 1 to 30 masses with respect to 100 parts by mass of the fine particles (C) in the undercoat layer from the viewpoints of the above-described addition effect and the water resistance and ink absorbability of the undercoat layer itself. Part is preferable, and more preferably 3 to 20 parts by mass.

The upper layer coating liquid of the present invention is adjusted to a solid content concentration of about 5 to 65% by mass, and ^{2 to} 30 g / m ² , preferably 5 in terms of dry weight, from the viewpoint of surface gloss and occurrence of powder falling off of the ink absorbing layer. It is preferable to perform coating by a coating method described later so as to be ˜20 g / m ² .
The support used in the present invention may be transparent or opaque as long as it has air permeability. In the present invention, for example, high-quality paper, photographic paper base paper, drawing paper, image paper, art paper, coated paper, cast paper, craft paper, and the like, non-woven fabric, and the like can be used as appropriate according to the application. . From the viewpoint of recording paper productivity, the air permeability of the support measured in accordance with JIS-P-8117 is preferably 1,000 seconds / 100 ml or less, more preferably 500 seconds / 100 ml or less. Further, if the air permeability is too low, it can be easily damaged in actual use of the obtained recording medium.

  Various back coat layers can be coated on the support in the present invention for antistatic properties, transport properties, anticurling properties, and the like. The backcoat layer can contain an appropriate combination of inorganic antistatic agent, organic antistatic agent, latex, curing agent, pigment, surfactant and the like.

The production apparatus according to the present invention comprises a means for coating a coating liquid containing at least the polymer emulsion of the present invention on a support at a temperature exceeding the temperature sensitive point of the polymer emulsion, and a coating solution immediately after coating. Means for cooling the coating layer to a temperature below the temperature sensitive point, means for pressure-bonding the coating layer to a heated mirror-finished solid surface when the coating layer is wet, and means for drying the coating layer It is preferable that it is a manufacturing apparatus.
As means for coating on the support, various blade coaters, roll coaters, air knife coaters, bar coaters, rod blade coaters, curtain flow coaters, gate roll coaters, short dwell coaters, extrusion die coaters, size presses, sprays, etc. These various devices can be used on-machine or off-machine.

  For forming a plurality of coating layers on the support, simultaneous multilayer coating can be performed. The simultaneous multilayer coating can be performed, for example, by a coating method using an extrusion die coater or a curtain flow coater. An extrusion die coater is more preferable for the purpose of avoiding mixing or coalescence of a plurality of coating layers. When using an extrusion die coater, a plurality of coating solutions discharged at the same time are layered near the extrusion die coater discharge port, i.e., just before moving onto the support, and in that state, a multilayer coating is applied on the support. Is done. When performing the simultaneous multi-layer coating, in order to avoid mixing of a plurality of coating liquids, a barrier layer liquid (intermediate layer liquid) may be interposed between the coating layers and the coating layers simultaneously. it can. The barrier layer solution can be selected without particular limitation as long as it is difficult to mix with the upper and lower coating layers, but a liquid having thixotropic properties is preferably used. Examples of the liquid preferably used include aqueous solutions of polymers such as hydroxypropylmethylcellulose, methylcellulose, hydroxyethylmethylcellulose, polyvinylpyrrolidone and gelatin.

In addition, regarding the thickness of the base paper, a paper having good surface smoothness, such as a paper that is compressed during or after paper making by applying pressure, is preferable, and the basis weight is preferably 30 to 450 g / m ^2. .
As means for cooling the coating layer, known means such as natural cooling, a cold air blower, a blower, and a refrigerator can be used. A blower or a cool air blower is preferably used, and the temperature of the wind changes variously depending on the temperature sensitive point of the polymer emulsion of the present invention, preferably a temperature below the temperature sensitive point, and a temperature 5 ° C. or more lower than the temperature sensitive point. More preferred is a temperature that is 10 ° C. or more lower than the temperature sensitive point. When natural cooling is performed, it is preferable to set the temperature sensing point higher by 10 ° C. than the environmental temperature.

  The method of performing the cast finish in the present invention is a method in which, when the coating layer is in a wet state, the coating layer is pressed onto a heated mirror-finished solid surface and dried, and then peeled off from the solid surface to copy the mirror surface. This is generally called the cast method. The casting method is roughly classified into a wet casting method (direct method), a gelled casting method (solidification method), and a rewet casting method (rewetting method). The direct method is a method in which a coating solution is applied and then pressed onto a mirror-finished solid surface heated in an undried state (wet state) and dried. The solidification method is a method in which the coating layer composition is acidified. This is a method of coagulating with a solution, an alkaline solution or the like, and pressing it onto a heated mirror-finished solid surface. The solidification method includes a thermal solidification method in which the composition is irradiated with infrared rays to solidify the surface. The re-wetting method is a method in which a coating liquid is applied and dried, and then the coating layer composition is re-wet with a liquid mainly composed of water, and is pressure-bonded to a heated mirror-finished solid surface and dried. . In the present invention, any casting method may be used as necessary, but a direct method or a re-wetting method is preferable from the viewpoints of homogeneity inside the obtained coating layer and in-plane homogeneity of ink absorption, The direct method is most preferable from the viewpoint of productivity.

  In the present invention, the mirror-finished solid material used for the cast finish includes, for example, metals such as stainless steel, glass, polyacryl, polyethylene terephthalate, silicone resin, fluororesin, etc., but metals such as stainless steel Is the most excellent and presently preferred from the viewpoint of surface smoothness, and preferred shapes are cylindrical, flat, etc., but cylindrical is most preferred.

As means for drying the coating layer, known drying means such as a hot air dryer, a steam heating dryer, a far-infrared dryer and the like can be used. A hot air dryer is preferably used, and examples thereof include a drum dryer, an air cap dryer, an air foil dryer, an air conditioner dryer, and combinations thereof. The drying temperature varies depending on the type of dryer, but the temperature inside the dryer is 50 to 200 ° C, preferably 100 to 150 ° C.

  The recording medium of the present invention is useful for recording using an ink composition containing a water-soluble dye, an oil-soluble dye, an aqueous pigment, an oily pigment and the like. As the recording method, for example, an ink jet recording method in which printing is performed by ejecting fine droplets of the ink composition to attach the ink composition to the surface of the recording medium, and printing is performed by coloring the ink composition by heating. Examples include thermal recording, gravure printing, offset printing and other various printing methods, recording with a writing instrument such as a pen, and the recording medium of the present invention is particularly preferably used for printing by an inkjet recording method. That is, the polymer emulsion of the present invention, the method for producing the polymer emulsion of the present invention, the coating liquid for the recording medium of the present invention, and the method of producing the recording medium of the present invention are also preferred recording media for recording and printing by the above recording method. It is useful for manufacturing the ink jet recording medium, and particularly useful for manufacturing an ink jet recording medium.

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
In the following Examples and Comparative Examples, “parts” and “%” mean “parts by mass” and “% by mass”.

The number average particle diameter by the dynamic light scattering method was measured by using Nikkiso Co., Ltd .; Microtrac UPA-9230. When measuring the particle diameter of the polymer emulsion, it was measured at a temperature higher than the temperature sensitive point.
The average pore diameter, pore volume, and specific surface area were measured with nitrogen using an autosorb-1 manufactured by Cantachrome.
The pore size distribution was calculated by the BJH method.
The specific surface area was determined by the BET method.

The temperature sensitive point of the polymer compound (A) in the polymer emulsion used in the present invention is the temperature of the polymer emulsion obtained by adjusting the concentration of the polymer compound (A) to 10% by mass with an aqueous solvent. While decreasing, the viscosity of the emulsion was successively measured using a B-type viscometer, and the transition point at which the obtained temperature-viscosity curve changed rapidly was determined as the temperature sensitive point of the polymer compound (A).
The ink absorptivity at the time of printing was sensorially evaluated using a commercially available ink jet printer (manufactured by Seiko Epson; PM-G800) using a dye ink. The evaluation result was evaluated by a 10-level evaluation. The extremely good result was 10, the good result was 8, the slightly good result was 6, the slightly inferior result was 2, the inferior result was 2, and the extremely inferior result was 1.

Microcracks on the surface of the recording medium were observed with a digital microscope (manufactured by Scalar; DG-2), magnified 200 times, and evaluated on a 10-point scale. Ten very good results with almost no microcracks were obtained. 8. A slightly good result was 6, a slightly inferior result was 4, an inferior result was 2, and a very inferior result was 1.
The gloss of the recording medium surface was evaluated sensuously by looking at the reflection of a fluorescent lamp. The evaluation results were evaluated on a 10-point scale, with 10 being a very good result, 8 being a good result, 6 being a slightly good result, 4 being a slightly inferior result, 2 being a poor result, and 1 being a very poor result.

(Preparation Example 1)
In a reaction vessel equipped with a stirrer, a reflux condenser, a dropping tank, and a thermometer, 202 parts of water was added to bring the inside of the reaction vessel to 80 ° C. Next, 3 parts of 29% aqueous solution of “Coatamine 86W” (manufactured by Kao Corporation, cationic surfactant: trade name), “Emulgen 1135S-70” (manufactured by Kao Corporation, nonionic surfactant: commodity Name) 2 parts 70% aqueous solution, 2 parts 70% aqueous solution of N, N-dimethylaminopropylacrylamide methyl chloride quaternary salt, 1 part dimethylaminoethyl methacrylate, 1 part 70% aqueous solution of methanesulfonic acid and 2, 2 4 parts of a 3% aqueous solution of '-azobis (2-methylpropionamidine) dibasic acid salt was added into the reactor. 5 minutes later, 1 part of diacetone acrylamide, 6 parts of methyl methacrylate, 6 parts of butyl acrylate, 6 parts of styrene, 1 part of 2-hydroxyethyl methacrylate and 2,2′-azobis (2- A solution in which 4 parts of a 3% aqueous solution of (methylpropionamidine) dibasic acid was dissolved was started to be added to the reaction vessel, and the addition was completed over 30 minutes. After the addition was completed, the liquid temperature in the reaction vessel was maintained at 80 ° C. for 45 minutes, and then 832 parts of water was added with 170 parts of N-isopropylacrylamide, 5 parts of 2-hydroxyethyl methacrylate, and N, N-dimethylaminopropylacrylamide methyl chloride. 2 parts of 70% aqueous solution of quaternary salt, 4 parts of dimethylaminoethyl methacrylate, 1 part of N, N′-methylenebis (acrylamide), 4 parts of 70% aqueous solution of methanesulfonic acid, 10 parts of 29% aqueous solution of Cotamine 86W and 2 parts , 2′-azobis (2-methylpropionamidine) dibasic acid 20% 3% aqueous solution, 5 parts of styrene and 22 parts of methyl methacrylate were added to the reaction vessel, respectively. The addition was completed over time. After the addition was completed, the temperature in the reaction vessel was kept at 80 ° C. for 30 minutes, and then cooled to 40 ° C. to obtain a polymer emulsion 7 having a number average particle size of 260 nm. The temperature point was measured and found to be 25 ° C. The main monomer content [(main monomer (M) addition mass) / (main monomer (M) addition mass + submonomer (N) addition amount) × 100] in the shell part of the polymer emulsion 7 is 82% by mass. there were. The polymer emulsion 7 was stored in a thermostat controlled at 40 ° C.

(Preparation Example 2)
In a reaction vessel equipped with a stirrer, a reflux condenser, a dropping tank, and a thermometer, 202 parts of water was added to bring the inside of the reaction vessel to 80 ° C. Next, 3 parts of 29% aqueous solution of “Coatamine 86W” (manufactured by Kao Corporation, cationic surfactant: trade name), “Emulgen 1135S-70” (manufactured by Kao Corporation, nonionic surfactant: commodity 2 parts of 70% aqueous solution of No. 2) and 4 parts of 3% aqueous solution of 2,2′-azobis (2-methylpropionamidine) dibasic acid salt were added into the reactor. After 5 minutes, 1 part of methacrylamide, 1 part of dimethylaminoethyl methacrylate, 6 parts of styrene, 6 parts of methyl methacrylate, 6 parts of butyl acrylate and 2,2′-azobis (2-methylpropionamidine) Addition of 4 parts of a 3% dibasic acid solution into the reaction vessel was started, and the addition was completed over 30 minutes. After completion of the addition, the temperature in the reaction vessel was kept at 80 ° C. for 30 minutes, and then 155 parts of N-isopropylacrylamide and 2 parts of 70% aqueous solution of N, N-dimethylaminopropylacrylamide methyl chloride quaternary salt were added to 656 parts of water. 3 parts of dimethylaminoethyl methacrylate, 1 part of N, N′-methylenebis (acrylamide), 4 parts of 70% aqueous solution of methanesulfonic acid, 10 parts of 29% aqueous solution of Cotamine 86W and 2,2′-azobis (2-methyl) Addition of 20 parts of a 3% aqueous solution of propionamidine) dibasic acid and 40 parts of butyl acrylate was started in the reaction vessel, and the addition was completed over 3.5 hours. The liquid temperature in the reaction vessel was kept at 80 ° C. during the addition and for 1 hour after the completion of the addition, and then cooled to 40 ° C. to obtain a polymer emulsion 3 having a number average particle size of 200 nm. The temperature point was measured and found to be 7 ° C. The main monomer content [(main monomer (M) addition mass) / (main monomer (M) addition mass + submonomer (N) addition amount) × 100] in the shell part of the polymer emulsion 3 is 78% by mass. there were

(Preparation Example 3)
In a reaction vessel equipped with a stirrer, a reflux condenser, a dropping tank, and a thermometer, 202 parts of water was added to bring the inside of the reaction vessel to 80 ° C. Next, 3 parts of 29% aqueous solution of “Coatamine 86W” (manufactured by Kao Corporation, cationic surfactant: trade name), “Emulgen 1135S-70” (manufactured by Kao Corporation, nonionic surfactant: commodity 2 parts of 70% aqueous solution of No. 2) and 4 parts of 3% aqueous solution of 2,2′-azobis (2-methylpropionamidine) dibasic acid salt were added into the reactor. After 5 minutes, a mixture of 1 part dimethylaminoethyl methacrylate, 6 parts styrene, 6 parts methyl methacrylate, 6 parts butyl acrylate and 2,2′-azobis (2-methylpropionamidine) dibasic acid salt Addition of 4 parts of a 3% aqueous solution into the reaction vessel was started, and the addition was completed over 1 hour. After the addition was completed, the temperature in the reaction vessel was kept at 80 ° C. for 30 minutes, and then 95 parts of N-isopropylacrylamide and 2 parts of 70% aqueous solution of N, N-dimethylaminopropylacrylamide methyl chloride quaternary salt were added to 656 parts of water. 3 parts of dimethylaminoethyl methacrylate, 0.3 part of N, N′-methylenebis (acrylamide), 4 parts of 70% aqueous solution of methanesulfonic acid, 10 parts of 29% aqueous solution of Cotamine 86W and 2,2′-azobis (2 -Methylpropionamidine) A solution obtained by dissolving 20 parts of a 3% aqueous solution of dibasic acid and 105 parts of methyl methacrylate were respectively added to the reaction vessel, and the addition was completed over 2 hours. The liquid temperature in the reaction vessel was kept at 80 ° C. during the addition and for 1 hour after the completion of the addition, and then cooled to 40 ° C. to obtain a polymer emulsion 5 having a number average particle size of 150 nm. The temperature point was measured and found to be 1 ° C. Further, the main monomer content [main monomer (M) addition mass / main monomer (M) addition mass + submonomer (N) addition amount) × 100] of the shell portion of the polymer emulsion 5 was 46 mass%. The polymer emulsion 5 was stored in a thermostat controlled at 40 ° C.

(Preparation Example 4)
Distilled water was mixed with a sodium silicate solution (No. 3 sodium silicate, manufactured by Tokuyama Corporation) having a SiO ₂ concentration of 30% by mass and a SiO ₂ / Na ₂ O molar ratio of 3.1, and a SiO ₂ concentration of 4.0% by mass. A dilute aqueous sodium silicate solution was prepared. This aqueous solution was passed through a column filled with a hydrogen-type cation exchange resin (Diaion SK-1B, manufactured by Mitsubishi Chemical Corporation) to prepare an active silicic acid aqueous solution. The obtained active silicic acid aqueous solution had a SiO ₂ concentration of 4.0% by mass and a pH of 2.9.
In a glass reaction vessel, 500 g of distilled water was heated to 100 ° C. While maintaining the hot water at 100 ° C., a total of 660 g of the above active silicic acid aqueous solution was added at a rate of 2 g / min.
The reaction solution was a semi-gelled suspension that was viscous and translucent as a whole.

An amount of 6.28 g of trimethoxymethylsilane corresponding to 23.8% by mass of SiO ₂ contained in this dispersion was added all at once, and the mixture was kept at 100 ° C. for 30 minutes with stirring to prepare a seed solution. The seed particles had a specific surface area of 810 m ² / g and a pore volume of 0.5 ml / g. To the seed solution, 0.030 mol of potassium hydroxide was added and stabilized, and the mixture was heated to 100 ° C. A total of 2480 g of the above active silicic acid aqueous solution was added to the seed solution at a rate of 2 g / min. After the addition of activated silicic acid was completed, the solution was kept as it was at 100 ° C. and heated to reflux for 6 hours to obtain a silica fine particle aggregate suspension.
The pH of the silica fine particle aggregate suspension was 9.7, and white silica aggregates settled when left standing. The above-mentioned silica fine particle aggregate suspension is treated twice at a treatment pressure of 1500 kg / m ² using an ultra-high pressure homogenizer [manufactured by Mizuho Kogyo Co., Ltd., Microfluidizer M110-E / H type] to disperse colloidal silica. Liquid 1 was prepared to 20%.
The particle diameter of the silica dispersion 1 was about 200 nm.

(Preparation Example 5)
Water is added to dry silica (manufactured by Nippon Aerosil Co., Ltd., A50: trade name, hereinafter referred to as A50) to a solid content of 15%, and dispersed using an ultrasonic disperser to obtain silica dispersion 2. It was.
(Preparation Example 6)
Commercially available vapor phase silica (trade name: Aerosil A200, manufactured by Nippon Aerosil) was dispersed using an ultrasonic disperser to prepare a 15% dispersion having an average secondary particle size of 80 nm. 10 parts of diallyldimethylammonium chloride-acrylamide copolymer (trade name: PAS-J-81, manufactured by Nitto Boseki Co., Ltd.) was added as a cationic compound to the dispersion, and again using an ultrasonic disperser. Dispersed and prepared with water so as to be a 10% dispersion, thereby obtaining a silica dispersion 3 having an average secondary particle diameter of 150 nm.

[Example 1]
5% aqueous solution of partially suspended polyvinyl alcohol (manufactured by Kuraray Co., Ltd., PVA235: trade name), 3% boric acid aqueous solution, ethylene glycol in A50 / PVA235 / boric acid / After adding ethylene glycol = 100/30/4/5 (dry mass ratio), coat with a bar coater on one side of a 190 g / m ² base paper (Zita Snow Kona 190, trade name). Work and dry to obtain a lower layer. The coating amount at this time was 10 g / m ² in terms of dry mass.

Next, to the silica dispersion 3 obtained in Preparation Example 6, the polymer emulsion 1 obtained in Preparation Example 1 is heated to 60 ° C. at a ratio of A200 / polymer emulsion 1 = 100/20 (dry mass ratio). Were added and mixed to prepare a coating liquid 1.
On the lower layer, after applying the coating liquid at 60 ° C. with a bar coater in which the coating liquid 1 is heated to 60 ° C., linear pressure is applied to a mirror drum having a surface temperature of 100 ° C. in a wet state. The film was pressure-bonded at 100 kg / cm, dried and then released to obtain a glossy ink jet recording medium. The coating amount of the coating liquid 1 at this time was 10 g / m ² in terms of dry mass. Table 1 shows the evaluation results of the ink jet recording paper.

[Example 2]
A recording medium was obtained in the same manner as in Example 1 except that propylene glycol was used instead of ethylene glycol in Example 1. Table 1 shows the evaluation results of the ink jet recording paper.
[Example 3]
A recording medium was obtained in the same manner as in Example 1 except that glycerin (polyvinyl alcohol dissolution temperature; 160 ° C.) was used instead of ethylene glycol in Example 1. Table 1 shows the evaluation results of the ink jet recording paper.

[Example 4]
A recording medium was obtained in the same manner as in Example 1 except that the polymer emulsion 2 obtained in Preparation Example 2 was used instead of the polymer emulsion 1 in Example 3. Table 1 shows the evaluation results of the ink jet recording paper.
[Example 5]
A recording medium was obtained in the same manner as in Example 1 except that the polymer emulsion 3 obtained in Preparation Example 3 was used instead of the polymer emulsion 1 in Example 3. Table 1 shows the evaluation results of the ink jet recording paper.

[Example 6]
A 5% aqueous solution of partially suspended polyvinyl alcohol (manufactured by Kuraray Co., Ltd., PVA235: trade name) and glycerin in the silica dispersion 1 obtained in Preparation Example 4 were dispersed in dispersion 1 / PVA235 / glycerin = 100/30/0. After adding to 5 (dry mass ratio), a lower layer was obtained by coating and drying on one side of a 190 g / m ² base paper (Kita Snow 190, trade name, manufactured by Zizuta Corporation) with a bar coater. The coating amount at this time was 10 g / m ² in terms of dry mass.
Next, in the A200 dispersion 2 obtained in Preparation Example 6, the polymer emulsion 2 obtained in Preparation Example 2 is heated to 60 ° C. at a ratio of A200 / polymer emulsion 1 = 100/20 (dry mass ratio). Were added and mixed to prepare a coating liquid 1.

On the lower layer, after applying the 60 ° C. coating solution with a bar coater heated to 60 ° C., the coating layer is wet and the surface temperature is 100 ° C. The film was pressure-bonded at a pressure of 100 kg / cm, dried and then released to obtain a glossy ink jet recording medium. The coating amount of the coating liquid 1 at this time was 10 g / m ² in terms of dry mass. Table 1 shows the evaluation results of the ink jet recording paper.

[Example 7]
A recording medium was obtained in the same manner as in Example 6 except that the blending ratio of the coating liquid in Example 6 was changed to dispersion 1 / PVA235 / glycerin = 100/30/5 (dry mass ratio). . Table 1 shows the evaluation results of the ink jet recording paper.
[Example 8]
A recording medium was obtained in the same manner as in Example 6 except that the blending ratio of the coating liquid in Example 6 was changed to dispersion 1 / PVA235 / glycerin = 100/30/10 (dry mass ratio). . Table 1 shows the evaluation results of the ink jet recording paper.

[Example 9]
A recording medium was obtained in the same manner as in Example 6 except that the blending ratio of the coating liquid in Example 6 was changed to dispersion 1 / PVA235 / propylene glycol = 100/30/75 (dry mass ratio). It was. Table 1 shows the evaluation results of the ink jet recording paper.
[Example 10]
Recording was carried out in the same manner as in Example 7, except that the blending ratio of the upper layer coating solution of Example 7 was changed to A200 / polymer emulsion 1 / 1-butanol = 100/20/20 (dry mass ratio). A medium was obtained. Table 1 shows the evaluation results of the ink jet recording paper.

[Comparative Example 1]
A recording medium was obtained in the same manner as in Example 1 except that ethylene glycol of Example 1 was not added. Table 1 shows the evaluation results of the ink jet recording paper.

  According to the present invention, it is possible to efficiently produce an ink jet recording medium that does not generate microcracks excellent in ink absorbability, surface gloss, and image quality, and the industrial utility value is very large.

Claims (8)

  A lower layer coating solution containing at least a pigment, a binder, and a polyhydric alcohol is coated on the support, and the layer is hydrophilic in the temperature range below a certain temperature (temperature sensitive point) on the lower layer. Mirror surface in which the coating layer is heated in a wet state after coating an upper layer coating solution containing a polymer emulsion containing a hydrophobic polymer compound (A) in a temperature range exceeding the point A method for producing a glossy cast paper for ink jet, characterized by pressure-bonding to a finished solid surface and imparting gloss to the surface of a coating layer.   The method for producing glossy cast paper for ink jet according to claim 1, wherein the binder is polyvinyl alcohol.   The method for producing glossy cast paper for ink jet according to claim 1 or 2, wherein the polyhydric alcohol is a plasticizer of polyvinyl alcohol.   The polymer emulsion contains 50% by mass or more of a nonionic N-substituted (meth) acrylamide derivative, and a polymer compound exhibiting hydrophobicity at a temperature sensitive point of 25 ° C. or lower and / or a temperature range exceeding 25 ° C. ( The method for producing glossy cast paper for inkjet according to any one of claims 1 to 3, wherein the emulsion is a polymer emulsion containing A).   The method according to any one of claims 1 to 4, further comprising a step of cooling to a temperature not higher than the temperature sensitive point after coating on the support at a temperature exceeding the temperature sensitive point of the polymer compound (A). The manufacturing method of the glossy cast paper for inkjet as described.   The lower layer coating liquid used for the manufacturing method of the glossy cast paper for inkjet as described in any one of Claims 1-5.   The upper layer coating liquid used for the manufacturing method of the glossy cast paper for inkjet as described in any one of Claims 1-5.   The glossy cast paper for inkjets manufactured by the manufacturing method of the glossy cast paper for inkjets as described in any one of Claims 1-5.