JP2008132787A - Method for manufacturing silica preliminary dispersion, silica finely pulverized particle dispersion liquid, and ink accepting layer application liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a silica preliminary dispersion liquid and a silica finely pulverized particle dispersion liquid with excellent handleabilities when an ink accepting layer application liquid is prepared by using the silica finely pulverized particle dispersion liquid prepared by furthermore finely pulverizing and dispersing the silica preliminary dispersion prepared by preliminarily dispersing a gas phase process silica, and to provide a method for manufacturing the ink accepting layer application liquid using the silica finely pulverized particle dispersion. <P>SOLUTION: The silica preliminary dispersion liquid is manufactured by kneading the gas phase process silica in the presence of a boric acid compound and a cationic polymer and at pH in a range of 2-5, and the silica finely pulverized particle dispersion liquid is manufactured by furthermore finely pulverizing and dispersing the silica preliminary dispersion liquid. In addition, the ink accepting layer application liquid is prepared by adding at least a water-soluble resin to the silica finely pulverized particle dispersion liquid. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a silica pre-dispersion liquid used in an ink-receiving layer coating liquid for forming an ink-receiving layer of an inkjet recording medium, and silica used in an ink-receiving layer coating liquid obtained by further atomizing and dispersing the pre-dispersion liquid. The present invention relates to a method for producing an atomized dispersion, and a method for producing an ink-receiving layer coating liquid in which a binder or the like is added to the silica atomized dispersion.

  In recent years, with the rapid development of the information industry, various information processing systems have been developed, and recording methods and apparatuses suitable for the information processing systems have been developed and put into practical use. Among the above recording methods, the inkjet recording method is capable of recording on a variety of recording materials, the hardware (device) is relatively inexpensive, compact, and excellent in quietness. Of course, it has been widely used in so-called home use.

  In addition, with the recent increase in resolution of inkjet printers, various recording materials have been developed, such as so-called photographic-like high-quality recorded matter. From the viewpoint of providing commercial value as a recording material, it has excellent ink absorbability and good image storage stability after recording, that is, the image may be faded or deteriorated by long-term storage. Not required.

For ink jet recording provided with an ink receiving layer having a high porosity and a three-dimensional structure formed from inorganic pigment fine particles such as vapor-phase method silica and water-soluble resins such as polyvinyl alcohol as an ink absorption enhancement A sheet is disclosed (for example, see Patent Documents 1 to 3), and a high-resolution image can be formed.
The ink receiving layer is formed by applying an ink receiving layer coating liquid to a support. The coating liquid is usually prepared by preparing a pre-dispersion liquid composed of a kneaded mixture of inorganic pigment fine particles, and further adding this pre-dispersion liquid to fine particles. Inorganic pigment fine particle dispersion liquid (this dispersion liquid) that has been subjected to a chemical dispersion treatment is added, and a binder, a mordant, a crosslinking agent, and the like are added to the inorganic pigment fine particle dispersion liquid to form an ink receiving layer coating liquid.
By the way, gas phase method silica, which is one of the inorganic pigments, is very fine particles and therefore has a strong interaction between the particles. When gas phase method silica is added to and mixed with a dispersion medium such as water, the pH of the liquid is 4. It shows ~ 5 and becomes thixotropic, and the liquid after mixing and dispersion has high viscosity and low handling properties. Further, when the atomization dispersion is further performed using a pre-dispersion liquid having a high viscosity, the viscosity of the obtained dispersion liquid (main dispersion liquid) or the ink receiving layer coating liquid tends to be high. Therefore, when vapor phase method silica is used as the inorganic pigment added to the ink receiving layer, it is not easy to prepare the pre-dispersion liquid and the atomized dispersion liquid.

Therefore, conventionally, for example, after vapor phase method silica is dispersed in water to prepare a silica pre-dispersion, a boric acid compound and a cationic polymer are added to this to adjust the pH to 5-8, and further atomization dispersion treatment is performed. To prepare a silica atomized dispersion (paragraphs 0043 to 0045 of Patent Document 4 below), or to add silica, water, boric acid and borax to vapor phase silica, and knead and disperse at pH 5 to 8 to prepare a silica preliminarily. A method is known in which a dispersion is prepared, a cationic polymer is added to the dispersion, and further atomized and dispersed to prepare a silica atomized dispersion (paragraphs 0046 to 0049 of Patent Document 4 below).
However, Patent Document 4 does not describe kneading at pH 2 to 5 in the presence of boric acid and a cationic polymer when preparing a silica pre-dispersion.
Further, in the method using borax, sodium is contained in the ink receiving layer, and there is a problem that bleeding occurs when image recording is performed.

Japanese Patent Laid-Open No. 10-203006 Japanese Patent Laid-Open No. 10-217601 JP-A-11-20306 JP 2002-79741 A

  The present invention has been made in view of the above problems, and an object thereof is to provide a method for producing a low-viscosity silica pre-dispersion and a silica atomization dispersion excellent in handling properties. Another object of the present invention is to provide a method for producing an ink receiving layer coating solution using the silica atomized dispersion.

The above-described problems are solved by providing the following silica pre-dispersion, silica atomization dispersion, and ink receiving layer coating solution.
(1) A silica pre-dispersion liquid for preparing a coating liquid for an ink receiving layer of an ink jet recording medium using a silica atomization dispersion liquid obtained by further atomizing and dispersing a silica pre-dispersion liquid obtained by pre-dispersing vapor phase silica. A method for producing an ink-receiving layer for an ink jet recording medium, characterized in that vapor phase method silica is kneaded in the presence of a boric acid compound and a cationic polymer in a pH range of 2 or more and less than 5 A method for producing a silica pre-dispersion when preparing a liquid.
(2) Silica pre-dispersion when preparing a coating liquid for an ink receiving layer of an ink jet recording medium according to (1), wherein the vapor phase silica has an average primary particle diameter of 5 nm to 30 nm. Liquid manufacturing method.
(3) A method for producing a silica finely divided dispersion used when preparing a coating liquid for an ink-receiving layer of an ink jet recording medium, wherein vapor phase silica is prepared in the presence of a boric acid compound and a cationic polymer and has a pH of 2 The silica pre-dispersion liquid obtained by kneading in a range smaller than 5 is further atomized and dispersed, and is used for preparing a coating liquid for an ink receiving layer of an ink jet recording medium. Liquid manufacturing method.
(4) A method for producing a coating solution for an ink receiving layer of an ink jet recording medium, which is obtained by kneading gas phase method silica in the presence of a boric acid compound and a cationic polymer and having a pH of 2 or more and less than 5. A method for producing a coating liquid for an ink receiving layer of an ink jet recording medium, comprising adding at least a water-soluble resin to a silica atomized dispersion obtained by further atomizing and dispersing the silica pre-dispersed liquid.

  The silica pre-dispersion obtained by the method for producing a silica pre-dispersion of the present invention has a low viscosity, and the silica pre-dispersion dispersion is further atomized and dispersed to prepare a silica atomized dispersion as described above. By using the silica pre-dispersed liquid obtained as described above, the atomization dispersion treatment is easy and the handling property is excellent. Further, the ink receiving layer coating solution prepared using the silica pre-dispersion and the silica atomization dispersion of the present invention has a low viscosity and excellent coating properties.

[Method for Producing Silica Pre-Dispersion and Silica Atomization Dispersion Used for Ink Receptor Layer Coating Liquid for Forming Inkjet Recording Medium Ink Receptive Layer]
The silica pre-dispersion liquid of the present invention is a pre-dispersion liquid used in an ink-receiving layer coating liquid for forming an ink-receiving layer of an ink jet recording medium, and vapor phase silica is adjusted to pH in the presence of a boric acid compound and a cationic polymer. Is kneaded in a range of 2 or more and less than 5.
When the vapor phase silica is added to water, the pH of the solution becomes 5 or less, and the thixotropic property is exhibited and the handling property is deteriorated. However, in the presence of the boric acid compound and the cationic polymer as described above, the pH is 2 or more and 5 When kneaded and dispersed in a smaller range, the viscosity does not increase and a low-viscosity silica pre-dispersion is obtained. When the silica pre-dispersion is further dispersed to prepare a silica atomized dispersion, the silica pre-dispersion obtained as described above is used, whereby the dispersion is easy and the handling property is excellent.
Further, the ink receiving layer coating solution prepared using the silica pre-dispersion and the silica atomization dispersion of the present invention has a low viscosity and excellent coating properties.

The pre-dispersion liquid of the present invention is obtained by adding and kneading gas phase method silica fine particles to an aqueous liquid containing a boric acid compound and a cationic polymer. The method for preparing the aqueous liquid is not particularly limited, and the vapor phase silica fine particles may be added as they are or as an aqueous dispersion. Kneading is performed with a high-speed rotary stirrer or the like. When the pH of the aqueous liquid is not in the pH range, kneading is performed after adjusting the pH appropriately.
In the present invention, “pre-dispersion” of vapor-phase process silica simply refers to a treatment in which vapor-phase process silica is made to conform to an aqueous liquid. There should be no phenomenon such as aggregation.

The atomized dispersion of the present invention is obtained by further atomizing and dispersing the pre-dispersed liquid with a disperser, and measuring the liquid after atomization with a particle size measuring instrument (for example, LA910 manufactured by HORIBA). Then, it means to atomize so that the proportion of coarse particles having a volume average particle size of 5 μm or more which are coarse particles is 5% or less.
Atomization is performed by refining the pre-dispersed liquid using a disperser. Examples of the disperser include a high-speed rotating disperser, a medium stirring disperser (such as a ball mill and a sand mill), an ultrasonic disperser, a colloid. Various conventionally known dispersers such as a mill disperser and a high-pressure disperser can be used. From the standpoint of efficiently dispersing the formed fine particles, a medium stirring type disperser, a colloid mill disperser or a high pressure disperser is preferable.

Hereinafter, the vapor phase silica, boric acid compound and cationic polymer used for the pre-dispersion liquid will be described.
(Gas phase method silica)
Silica fine particles are generally roughly classified into wet method particles and dry method (vapor phase method) particles according to the production method, and the vapor phase silica according to the present invention is dry method (gas phase method) particles. The vapor phase method is a method by high-temperature vapor phase hydrolysis of silicon halide (flame hydrolysis method), a method in which silica sand and coke are heated and reduced and vaporized by an arc in an electric furnace and oxidized with air (arc). Method) to obtain anhydrous silica is the mainstream, and “gas phase method silica” means anhydrous silica fine particles obtained by the gas phase method. In the wet method, active silica is produced by acid decomposition of silicate, and this is a method in which this is appropriately polymerized and agglomerated and precipitated to obtain hydrous silica, which may be used together with gas phase method silica. .

Vapor phase silica is different from hydrous silica in terms of the density of silanol groups on the surface, the presence or absence of vacancies, etc., and exhibits different properties, but is suitable for forming a three-dimensional structure with a high porosity. The reason for this is not clear, but in the case of hydrous silica, the density of silanol groups on the fine particle surface is high at 5 to 8 / nm ² , and the silica fine particles tend to aggregate (aggregate) easily. In the case of the method silica, the density of silanol groups on the surface of the fine particles is 2 to 3 / nm ² , so that it is sparse soft agglomeration (flocculate), resulting in a structure with a high porosity. Is done.

  Vapor phase silica has a particularly large specific surface area, so it has high ink absorption and retention efficiency, and low refractive index, so it provides transparency to the ink receiving layer when dispersed to an appropriate particle size. And high color density and good color development can be obtained. The transparency of the receiving layer is important from the viewpoint of obtaining a high color density and good color developing gloss even when applied to uses such as photo glossy paper.

  The average primary particle diameter of the vapor phase silica is preferably 3 nm to 30 nm, more preferably 10 nm or less, and particularly preferably 3 to 10 nm. Vapor phase silica is easy to adhere to each other by hydrogen bonds with silanol groups, so it can form a structure with a large porosity when the average primary particle size is 30 nm or less, effectively improving ink absorption characteristics. In addition, the transparency and surface gloss of the ink receiving layer can be enhanced. In addition, the vapor phase method silica may be used as primary particles or may be contained in a state where secondary particles are formed.

  Vapor phase silica is preferably used in a dispersed state. Vapor phase silica can be dispersed by using a cationic resin, which will be described later, as a dispersant (aggregation inhibitor) and can be used as a vapor phase silica dispersion.

  Other inorganic fine particles can be used in combination with the vapor phase silica. Other inorganic fine particles include, for example, other silica fine particles, colloidal silica, titanium dioxide, barium sulfate, calcium silicate, zeolite, kaolinite, halloysite, mica, talc, calcium carbonate, magnesium carbonate, calcium sulfate, zinc oxide, water Examples thereof include zinc oxide, alumina, aluminum silicate, calcium silicate, magnesium silicate, zirconium oxide, zirconium hydroxide, cerium oxide, lanthanum oxide, and yttrium oxide. These fine particles can be contained in the form of primary particles or secondary particles, and the average primary particle diameter is preferably 2 μm or less, more preferably 200 nm or less.

  The total content (solid content) of the vapor phase silica (and other inorganic fine particles if necessary) in the ink receiving layer is preferably 60% by mass or more, and more preferably 65% by mass or more. When the total content is 60% by mass or more, a more favorable porous structure can be formed, and an ink jet recording medium having sufficient ink absorbability can be obtained. Here, the amount (solid content) in the ink receiving layer is an amount calculated based on components other than water in the composition constituting the ink receiving layer.

  When the vapor phase silica (and other inorganic fine particles if necessary) is used for an ink jet recording medium, for example, JP-A Nos. 10-81064, 10-119423, 10-157277, 10-217601, 11-348409, JP-A-2001-138621, JP-A-2000-431401, JP-A-2000-21235, JP-A-2000-309157, JP-A-2001-968627, JP-A-2001-138627, JP-A-11-91242, Also preferred are the embodiments disclosed in JP-A Nos. 8-2087, 8-2090, 8-2091, 8-2093, 8-174992, 11-192777, JP-A-2001-301314, etc. Can be used.

  Further, for the purpose of improving the dispersibility, the surface of the fine particles of the vapor phase method silica may be treated with a silane coupling agent. As the silane coupling agent, an organic functional group (for example, a vinyl group, an amino group, an epoxy group, a mercapto group, a chloro group, an alkyl group, a phenyl group, an ester group, etc.) in addition to the site where the coupling treatment is performed. What has is preferable.

(Boric acid compound)
Examples of the boric acid compound, boric acid, borates (eg, _{orthoborate, InBO 3, ScBO 3, YBO} 3, LaBO 3, Mg 3 (BO 3) 2, Co 3 (BO 3) 2, diborate Acid salts (eg, Mg ₂ B ₂ O ₅ , Co ₂ B ₂ O ₅ ), metaborates (eg, LiBO ₂ , Ca (BO ₂ ) ₂ , NaBO ₂ , KBO ₂ ), tetraborates (eg, _{Na 2 B 4 O 7 · 10H} 2 O), can be cited pentaborate _{(eg, KB 5 O 8 · 4H 2} O, Ca 2 B 6 O 11 · 7H 2 O, CsB 5 O 5) , etc. Of these, boric acid is preferred.
The addition amount of boric acid is preferably 0.1 to 15% by mass, more preferably 1 to 10% by mass with respect to the vapor phase silica.

(Cationic polymer)
As the cationic polymer, those having a primary to tertiary amino group or a quaternary ammonium base as a cationic functional group are suitably used.
Examples of the cationic polymer include a homopolymer of a monomer having a primary to tertiary amino group or a salt thereof, or a quaternary ammonium base (cationic monomer), the cationic monomer and another monomer ( Those obtained as copolymers or condensation polymers with non-cationic monomers) are preferred. Further, these cationic polymers can be used in any form of water-soluble polymer or water-dispersible latex particles.

  Examples of the cationic monomer include trimethyl-p-vinylbenzylammonium chloride, trimethyl-m-vinylbenzylammonium chloride, triethyl-p-vinylbenzylammonium chloride, triethyl-m-vinylbenzylammonium chloride, N, N-dimethyl- N-ethyl-Np-vinylbenzylammonium chloride, N, N-diethyl-N-methyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-Nn-propyl-Np-vinylbenzyl Ammonium chloride, N, N-dimethyl-Nn-octyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N-benzyl-Np-vinylbenzylammonium chloride, N, N-diethyl- -Benzyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N- (4-methyl) benzyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N-phenyl-Np- Vinylbenzylammonium chloride;

Trimethyl-p-vinylbenzylammonium bromide, trimethyl-m-vinylbenzylammonium bromide, trimethyl-p-vinylbenzylammonium sulfonate, trimethyl-m-vinylbenzylammonium sulfonate, trimethyl-p-vinylbenzylammonium acetate, trimethyl-m-vinyl Benzylammonium acetate, N, N, N-triethyl-N-2- (4-vinylphenyl) ethylammonium chloride, N, N, N-triethyl-N-2- (3-vinylphenyl) ethylammonium chloride, N, N-diethyl-N-methyl-N-2- (4-vinylphenyl) ethylammonium chloride, N, N-diethyl-N-methyl-N-2- (4-vinylphenyl) ethylammonium chloride Tate;

N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, N, N- Methyl chloride, ethyl chloride, methyl bromide of dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-diethylaminopropyl (meth) acrylamide , Quaternized products of ethyl bromide, methyl iodide or ethyl iodide, or sulfonates, alkyl sulfonates, acetates or alkyl carboxylates substituted with their anions.

  Specific examples of the compound include monomethyl diallylammonium chloride, trimethyl-2- (methacryloyloxy) ethylammonium chloride, triethyl-2- (methacryloyloxy) ethylammonium chloride, trimethyl-2- (acryloyloxy) ethylammonium chloride, Triethyl-2- (acryloyloxy) ethylammonium chloride, trimethyl-3- (methacryloyloxy) propylammonium chloride, triethyl-3- (methacryloyloxy) propylammonium chloride, trimethyl-2- (methacryloylamino) ethylammonium chloride, triethyl- 2- (methacryloylamino) ethylammonium chloride, trimethyl-2- (acryloylua) C) ethylammonium chloride, triethyl-2- (acryloylamino) ethylammonium chloride, trimethyl-3- (methacryloylamino) propylammonium chloride, triethyl-3- (methacryloylamino) propylammonium chloride, trimethyl-3- (acryloylamino) Propylammonium chloride, triethyl-3- (acryloylamino) propylammonium chloride;

N, N-dimethyl-N-ethyl-2- (methacryloyloxy) ethylammonium chloride, N, N-diethyl-N-methyl-2- (methacryloyloxy) ethylammonium chloride, N, N-dimethyl-N-ethyl- 3- (acryloylamino) propylammonium chloride, trimethyl-2- (methacryloyloxy) ethylammonium bromide, trimethyl-3- (acryloylamino) propylammonium bromide, trimethyl-2- (methacryloyloxy) ethylammonium sulfonate, trimethyl-3- And (acryloylamino) propylammonium acetate.
In addition, examples of copolymerizable monomers include N-vinylimidazole and N-vinyl-2-methylimidazole.

In addition, allylamine, diallylamine, derivatives thereof, salts and the like can also be used. Examples of such compounds include allylamine, allylamine hydrochloride, allylamine acetate, allylamine sulfate, diallylamine, diallylamine hydrochloride, diallylamine acetate, diallylamine sulfate, diallylmethylamine and salts thereof (for example, Hydrochloride, acetate, sulfate, etc.), diallylethylamine and salts thereof (for example, hydrochloride, acetate, sulfate, etc.), diallyldimethylammonium salt (chloride, acetic acid as counter anions of the salt) Ion, sulfate ion, etc.). In addition, since these allylamines and diallylamine derivatives are inferior in polymerizability in the form of amine, it is a general production method to polymerize in the form of a salt and desalting as required.
In addition, a polymerization unit such as N-vinylacetamide, N-vinylformamide or the like, which is converted into a vinylamine unit by hydrolysis after polymerization, and a salt thereof can be used.

The non-cationic monomer does not contain a basic or cationic moiety such as a primary to tertiary amino group or a salt thereof, or a quaternary ammonium base, and does not interact with a dye in an inkjet ink. Or a monomer having a substantially small interaction.
Examples of the non-cationic monomer include (meth) acrylic acid alkyl ester; (meth) acrylic acid cycloalkyl ester such as cyclohexyl (meth) acrylate; (meth) acrylic acid aryl ester such as phenyl (meth) acrylate; Aralkyl esters such as (meth) benzyl acrylate; Aromatic vinyls such as styrene, vinyl toluene and α-methylstyrene; Vinyl esters such as vinyl acetate, vinyl propionate and vinyl versatic acid; Allyl esters such as allyl acetate Halogen-containing monomers such as vinylidene chloride and vinyl chloride; vinyl cyanides such as (meth) acrylonitrile; olefins such as ethylene and propylene.

  The (meth) acrylic acid alkyl ester is preferably a (meth) acrylic acid alkyl ester having 1 to 18 carbon atoms in the alkyl moiety, specifically, for example, methyl (meth) acrylate or ethyl (meth) acrylate. Propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, (meth) Examples include octyl acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and the like. Among these, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and hydroxyethyl methacrylate are preferable. The non-cationic monomers can also be used alone or in combination of two or more.

Further, as the cationic polymer, polydiallyldimethylammonium chloride, polymethacryloyloxyethyl-β-hydroxyethyldimethylammonium chloride, polyethyleneimine, polyallylamine and derivatives thereof, polyamide-polyamine resin, cationized starch, dicyandiamide formalin condensate, dimethyl Addition of 2-hydroxypropylammonium salt polymer, polyamidine, polyvinylamine, dicyandiamide-formalin polycondensate, dicyanamide-cachinic resin represented by dicyanamide-diethylenetriamine polycondensate, polyamine-type katine resin, epichlorohydrin-dimethylamine polymer, dimethyldiallylammonium phosphorus chloride -SO ₂ copolymers, diallylamine salt -SO ₂ copolymer It may be mentioned as being also preferred.

Specific examples of the cationic polymer include JP-A Nos. 48-28325, 54-74430, 54-124726, 55-22766, 55-142339, 60-23850, and 60. -23851, 60-23852, 60-23853, 60-57836, 60-60643, 60-118834, 60-122940, 60-122941, 60-122294 No. 60-235134, JP-A-1-161236, U.S. Pat.Nos. 2,484,430, 2,548,564, 3,148,061, 3,309,690, 4,115,124, 4,124,386, 4,193,800, 4,273,853, JP 4282305, JP 4450224, JP-A-1-1612. No. 6, No. 10-81064, No. 10-119423, No. 10-157277, No. 10-217601, No. 11-348409, JP-A No. 2001-138621, No. 2000-43401, No. 2000-212235 No. 2000-309157, No. 2001-96897, No. 2001-138627, JP-A-11-91242, No.8-2087, No.8-2090, No.8-2091, No.8-2093 8-174992, 11-192777, and JP-A-2001-301314.
The addition amount of the cationic polymer is preferably 1 to 20% by mass, more preferably 2 to 10% by mass with respect to the vapor phase silica.

  When preparing the pre-dispersion liquid, various additives can be added. Examples of additives include various nonionic or cationic surfactants (anionic surfactants are not preferred for forming aggregates), antifoaming agents, nonionic hydrophilic polymers (polyvinyl alcohol, Polyvinyl pyrrolidone, polyethylene oxide, polyacrylamide, various sugars, gelatin, pullulan, etc.), nonionic or cationic latex dispersions, water-miscible organic solvents (ethyl acetate, methanol, ethanol, isopropanol, n-propanol, acetone, etc.) , Inorganic salts, pH adjusters, and the like, and these can be used as needed.

  In particular, a water-miscible organic solvent is preferable in that formation of minute lumps when mixing vapor phase silica and a cationic resin is suppressed. The water-miscible organic solvent is used in the dispersion in an amount of 0.1 to 20% by mass, particularly preferably 0.5 to 10% by mass.

[Ink-receiving layer coating solution for forming ink-receiving layer of ink jet recording medium]
The ink receiving layer coating liquid is prepared by adding and mixing predetermined components necessary for the ink receiving layer to the atomized dispersion. As the component, a water-soluble resin as a binder is necessary. In addition, a crosslinking agent, a mordant, and the like of the water-soluble resin can be used.
Further, when the ink receiving layer coating liquid is prepared, it can be dispersed using the disperser used for preparing the atomized dispersion.
(Water-soluble resin)
The ink receiving layer coating liquid according to the present invention contains a water-soluble resin.
Examples of the water-soluble resin include polyvinyl alcohol resins that are resins having a hydroxy group as a hydrophilic structural unit [polyvinyl alcohol (PVA), acetoacetyl-modified polyvinyl alcohol, cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, silanol-modified. Polyvinyl alcohol, polyvinyl acetal, etc.], cellulosic resins [methyl cellulose (MC), ethyl cellulose (EC), hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), hydroxypropyl cellulose (HPC), hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, etc.] , Chitins, chitosans, starch, resins with ether linkages [polyethylene oxide (PEO), Propylene oxide (PPO), polyethylene glycol (PEG), poly ether (PVE)], and resins having carbamoyl groups [polyacrylamide (PAAM), polyvinyl pyrrolidone (PVP), polyacrylic acid hydrazide, etc.] and the like. Moreover, the polyacrylic acid salt which has a carboxyl group as a dissociable group, maleic acid resin, alginate, gelatins, etc. can be mentioned.

Among these, from the viewpoints of layer transparency and coating formability, the type of water-soluble resin to be combined with gas phase method silica is important, and polyvinyl alcohol resins are particularly preferable.
Examples of the polyvinyl alcohol include Japanese Patent Publication No. 4-52786, Japanese Patent Publication No. 5-67432, Japanese Patent Publication No. 7-29479, Japanese Patent No. 2537827, Japanese Patent Publication No. 7-57553, Japanese Patent No. 2502998, Japanese Patent No. 3053231. JP-A-63-176173, JP-A-2604367, JP-A-7-276787, JP-A-9-207425, JP-A-11-58941, JP-A-2000-135858, JP-A-2001-205924, JP 2001-287444, JP 62-278080, JP 9-39373, JP 2750433, JP 2000-18801, JP 2001-213045, JP 2001-328345, JP 8 -324105, JP-A-11-348417, etc. It is below.

  Of these, those having a saponification degree of 90% or more, more preferably 95% or more are preferred. If the degree of saponification is less than 90%, the viscosity of the coating solution for forming the ink receiving layer is so high that coating becomes difficult, and layer formation may not be possible.

  The polyvinyl alcohol-based resin has a hydroxyl group in its structural unit, and since this hydroxyl group and the surface silanol group of the gas phase method silica form a hydrogen bond, a three-dimensional structure in which secondary particles of silica fine particles are network chain units. It becomes easy to form a network structure. By forming this three-dimensional network structure, it is considered that an ink receiving layer having a porous structure with a high porosity and sufficient strength can be formed. As described above, the porous ink receiving layer can absorb ink rapidly by capillary action, and can form dots with good roundness without ink bleeding.

The water-soluble resin may be used alone or in combination of two or more. The content of the water-soluble resin in the ink receiving layer is preferably 9 to 40% by mass, and more preferably 12 to 33% by mass with respect to the solid content (mass) of the layer.
In addition to the polyvinyl alcohol resin, other water-soluble resins may be used in combination. The amount of the polyvinyl alcohol-based resin in the total water-soluble resin when used in combination is preferably 50% by mass or more, and more preferably 70% by mass or more.

<Content ratio of gas phase method silica and water-soluble resin>
The mass content ratio [PB ratio (x / y)] of the vapor phase method silica (x) and the water-soluble resin (y) greatly affects the film structure and film strength of the ink receiving layer. That is, as the mass content ratio [PB ratio] increases, the porosity, pore volume, and surface area (per unit mass) increase, but the density and strength tend to decrease. The ink receiving layer according to the present invention has a PB ratio (x / y) that prevents a decrease in film strength due to the PB ratio being too large and cracks during drying, and the PB ratio is too small. From the viewpoint of preventing the ink absorbability from being lowered due to the void being easily blocked by the resin and decreasing the porosity, 1.5 to 10 is preferable.

  In addition, since stress may be applied to the recording sheet when passing through the conveyance system of the ink jet printer, the ink receiving layer needs to have sufficient film strength. Further, when cutting into a sheet shape, the ink receiving layer needs to have sufficient film strength in order to prevent cracking or peeling of the ink receiving layer. Considering these cases, the PB (x / y) is more preferably 5 or less, while it is more preferably 2 or more from the viewpoint of ensuring high-speed ink absorbency in an inkjet printer.

For example, a coating solution in which a vapor phase silica having an average primary particle size of 20 nm or less and a water-soluble resin are completely dispersed in an aqueous solution at a PB ratio (x / y) of 2 to 5 is applied on a support, When the coating layer is dried, a three-dimensional network structure is formed in which the secondary particles of silica fine particles are network chains, the average pore diameter is 30 nm or less, the porosity is 50 to 80%, and the pore specific volume is 0.5 ml. / G or more, and a translucent porous film having a specific surface area of 100 m ² / g or more can be easily formed.

(Crosslinking agent)
The ink receiving layer coating liquid in the invention preferably contains a crosslinking agent capable of crosslinking the water-soluble resin.
Boron compounds are preferred for crosslinking the above water-soluble resins, particularly polyvinyl alcohol resins. Examples of the boron compound, 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 ), tetraboric acid Salt (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 ), etc. Among them, borax, boric acid, and borate are preferable, and boric acid is particularly preferable in that a crosslinking reaction can be promptly caused.

  Moreover, the following compounds other than a boron compound can also be used. 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 and 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; melamine resins (for example, methylolmelamine, alkylated methylolmelamine) ;Epoxy resin;

Isocyanate compounds such as 1,6-hexamethylene diisocyanate; Aziridine compounds described in US Pat. Nos. 3,017,280 and 2,983,611; Carboximide compounds described in US Pat. No. 3,100,704; Glycerol triglycidyl Epoxy compounds such as ether; Ethyleneimino compounds such as 1,6-hexamethylene-N, N′-bisethyleneurea; Halogenated carboxaldehyde compounds such as mucochloric acid and mucophenoxycyclolic acid; 2,3-dihydroxy Dioxane compounds such as dioxane; Titanium lactate, aluminum sulfate, chromium alum, potash alum, metal-containing compounds such as zirconyl acetate and chromium acetate, polyamine compounds such as tetraethylenepentamine, and hydrazide compounds such as adipic acid dihydrazide It is a small molecule or polymer or the like containing an oxazoline group two or more. The above crosslinking agents may be used singly or in combination of two or more.

  1-50 mass% is preferable with respect to the mass of the water-soluble resin in a layer, and, as for the usage-amount of a crosslinking agent, 5-40 mass% is more preferable.

(mordant)
As the mordant, an organic mordant such as a cationic polymer (cationic mordant) and an inorganic mordant such as a water-soluble metal compound are preferable. The presence of the mordant in the ink receiving layer can stabilize the dye by interacting with the liquid ink having an anionic dye as a coloring material, and can obtain a high-density image, and it can be blurred and water-resistant over time. Can be improved.

  As the cationic polymer mordant, the cationic polymer can be used as a mordant.

  Examples of the inorganic mordant include polyvalent water-soluble metal salts and hydrophobic metal salt compounds. For example, magnesium, aluminum, calcium, scandium, titanium, vanadium, manganese, iron, nickel, copper, zinc, gallium, germanium, strontium, yttrium, zirconium, molybdenum, indium, barium, lanthanum, cerium, praseodymium, neodymium, samarium, Examples include salts or complexes of metals selected from europium, gadolinium, dysproprosium, erbium, ytterbium, hafnium, tungsten, bismuth.

  Specific examples include calcium acetate, calcium chloride, calcium formate, calcium sulfate, barium acetate, barium sulfate, barium phosphate, manganese chloride, manganese acetate, manganese formate dihydrate, manganese ammonium sulfate hexahydrate, chloride chloride Dicopper, ammonium copper (II) chloride dihydrate, copper sulfate, cobalt chloride, cobalt thiocyanate, cobalt sulfate, nickel sulfate hexahydrate, nickel chloride hexahydrate, nickel acetate tetrahydrate, nickel sulfate Ammonium hexahydrate, nickel amidosulfate tetrahydrate, alumina sulfate, alumina alum, basic polyaluminum hydroxide, sulfite alumina, thiosulfate alumina, polychlorinated alumina, alumina nitrate nonahydrate, alumina chloride hexahydrate , Ferrous bromide, ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, phenol Zinc sulfonate, zinc bromide, zinc chloride, zinc nitrate hexahydrate, zinc sulfate, titanium tetrachloride, tetraisopropyl titanate, titanium acetylacetonate, titanium lactate, zirconium acetylacetonate, zirconyl acetate, zirconyl sulfate, zirconium carbonate Ammonium, zirconyl stearate, zirconyl octylate, zirconyl nitrate, zirconium oxychloride,

Hydroxy zirconium chloride, chromium acetate, chromium sulfate, magnesium sulfate, magnesium chloride hexahydrate, magnesium citrate nonahydrate, sodium phosphotungstate, sodium tungsten citrate, 12 tungstophosphoric acid n hydrate, 12 tungsto Acid 26 hydrate, molybdenum chloride, 12 molybdophosphoric acid n hydrate, potassium nitrate, manganese acetate, germanium nitrate, strontium nitrate, yttrium acetate, yttrium chloride, yttrium nitrate, indium nitrate, lanthanum nitrate, lanthanum chloride lanthanum acetate, benzoic acid Lanthanum, cerium chloride, cerium sulfate, cerium octylate, praseodymium nitrate, neodymium nitrate, samarium nitrate, europium nitrate, gadolinium nitrate, dysprosium nitrate, erbium nitrate, glass Ytterbium, hafnium chloride, and bismuth nitrate.

Among the inorganic mordants, alumina-containing compounds, titanium-containing compounds, zirconium-containing compounds, and group IIIB series metal compounds (salts or complexes) of the periodic table are preferable.
The content of the ink receiving layer of the mordant is preferably ^{0.01~5g / m 2, 0.1~3g / m} 2 is more preferable.

  The ink-receiving layer coating solution may further contain various known additives, for example, acids, ultraviolet absorbers, antioxidants, fluorescent brighteners, monomers, polymerization initiators, polymerization inhibitors, if necessary. Anti-bleeding agents, preservatives, viscosity stabilizers, antifoaming agents, surfactants, antistatic agents, matting agents, anti-curling agents, water-proofing agents and the like can be added.

  When an acid is added to the ink receiving layer coating solution to adjust the surface pH of the ink receiving layer to 3 to 8, preferably 5 to 7.5, yellowing resistance of the white background can be improved. The surface pH can be measured by the A method (coating method) among the surface PH measurements determined by the Japan Paper Pulp Technology Association (J.TAPPI), for example, Kyoritsu Co., Ltd., which corresponds to the A method. It can be performed using a PH measurement set for paper “type MPC” manufactured by RIKEN.

  Specific examples of acids include formic acid, acetic acid, glycolic acid, oxalic acid, propionic acid, malonic acid, succinic acid, adipic acid, maleic acid, malic acid, tartaric acid, citric acid, benzoic acid, phthalic acid, isophthalic acid , Glutaric acid, gluconic acid, lactic acid, aspartic acid, glutamic acid, salicylic acid, salicylic acid metal salts (Zn, Al, Ca, Mg, etc.), methanesulfonic acid, itaconic acid, benzenesulfonic acid, toluenesulfonic acid, trifluoromethanesulfone Acid, styrenesulfonic acid, trifluoroacetic acid, barbituric acid, acrylic acid, methacrylic acid, cinnamic acid, 4-hydroxybenzoic acid, aminobenzoic acid, naphthalenedisulfonic acid, hydroxybenzenesulfonic acid, toluenesulfinic acid, benzenesulfinic acid, Sulfanilic acid, sulfamic acid, α-le Rucinic acid, β-resorcinic acid, γ-resorcinic acid, gallic acid, phloroglicin, sulfosalicylic acid, ascorbic acid, erythorbic acid, bisphenolic acid, hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, boric acid, boronic acid, etc. Can be mentioned. The amount of these acids added may be determined so that the surface PH of the ink receiving layer is 3-8.

  The above acid may be a metal salt (eg, sodium, potassium, calcium, cesium, zinc, copper, iron, aluminum, zirconium, lanthanum, yttrium, magnesium, strontium, cerium, etc.) or an amine salt (eg, ammonia, triethylamine). , Tributylamine, piperazine, 2-methylpiperazine, polyallylamine, etc.).

In addition, the ultraviolet absorber, antioxidant, bleeding inhibitor and the like act as preservability improvers and are preferable additives.
These UV absorbers, antioxidants and anti-bleeding agents that can be used in combination include alkylated phenolic compounds (including hindered phenolic compounds), alkylthiomethylphenolic compounds, hydroquinone compounds, alkylated hydroquinone compounds, tocopherol compounds, thiols Diphenyl ether compounds, compounds having two or more thioether bonds, bisphenolic compounds, O-, N- and S-benzyl compounds, hydroxybenzyl compounds, triazine compounds, phosphonate compounds, acylaminophenolic compounds, ester compounds, amide compounds, Ascorbic acid, amine antioxidant, 2- (2-hydroxyphenyl) benzotriazole compound, 2-hydroxybenzophenone compound, acrylate, water-soluble or hydrophobic metal salt, organic gold Compounds, metal complexes, hindered amine compounds (including TEMPO compounds), 2- (2-hydroxyphenyl) 1,3,5, -triazine compounds, metal deactivators, phosphite compounds, phosphonite compounds, hydroxyamine compounds, nitrones Compound, peroxide scavenger, polyamide stabilizer, polyether compound, basic auxiliary stabilizer, nucleating agent, benzofuranone compound, indolinone compound, phosphine compound, polyamine compound, thiourea compound, urea compound, hydrazide compound, amidine compound, sugar A compound, a hydroxybenzoic acid compound, a dihydroxybenzoic acid compound, a trihydroxybenzoic acid compound, and the like.

  Among these, alkylated phenolic compounds, compounds having two or more thioether bonds, bisphenolic compounds, ascorbic acid, amine-based antioxidants, water-soluble or hydrophobic metal salts, organometallic compounds, metal complexes, hindered amines It is preferable to use a combination of at least one of compounds, polyamine compounds, thiourea compounds, hydrazide compounds, hydroxybenzoic acid compounds, dihydroxybenzoic acid compounds and trihydroxybenzoic acid compounds.

  Specific examples of the compound include Japanese Patent Application No. 2002-13005, Japanese Patent Application Laid-Open No. 10-182621, Japanese Patent Application Laid-Open No. 2001-260519, Japanese Patent Application No. 4-34953, Japanese Patent Application No. 4-34513, Japanese Patent Application Laid-Open No. 11-170686, No. 4-34512, EP 1138509, JP-A-60-67190, JP-A-7-276808, JP-A-2001-94829, JP-A-47-10537, JP-A-58-111942, and JP-A-58-212844. 59-19945, 59-46646, 59-109055, 63-53544, JP 36-10466, 42-26187, 48-30492, 48-31255, 48-41572, 48-54965, 50-10726, U.S. Pat.No. 2,719,086, 3 No. 707,375, the 3,754,919 Patent, the 4,220,711 Patent,

Japanese Patent Publication Nos. 45-4699, 54-5324, European Published Patent Nos. 223739, 309401, 309402, 3105301, 310552, 459416, German Published Patent No. 3435443, Kaisho 54-48535, 60-107384, 60-107383, 60-125470, 60-125471, 60-125472, 60-287485, 60-287486, 60-287487, 60-287488, 61-160287, 61-18854, 61-2111079, 62-146678, 62-146680, 62-146679, 62- No. 282885, No. 62-262047, No. 63-051174, Nos. 63-89877, 63-88380 same issue, same 66-88381 JP, same 63-113536 issue,

63-163351, 63-203372, 63-224989, 63-251282, 63-267594, 63-182484, JP-A-1-239282, JP-A-2-262654, 2-71262, 3-121449, 4-291865, 4-291684, 5-611166, 5-119449, 5-188687, 5-188686, 5 No. 110490, No. 5-110437, No. 5-170361, No. 48-43295, No. 48-33212, US Pat. Nos. 4,814,262, No. 4,980,275, and the like. It is done.

Other components may be used alone or in combination of two or more. Other components may be added after being water-solubilized, dispersed, polymer-dispersed, emulsified or formed into oil droplets, or may be encapsulated in microcapsules. The amount of addition when other components are added is preferably 0.01 to 10 g / m ² .

  The ink-receiving layer coating liquid in the invention may contain a surfactant. As the surfactant, any of cationic, anionic, nonionic, amphoteric, fluorine, and silicon surfactants can be used. These surfactants may be used alone or in combination of two or more.

  Examples of the nonionic surfactant include polyoxyalkylene alkyl ethers and polyoxyalkylene alkyl phenyl ethers (for example, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyalkylene ether) Ethylene nonylphenyl ether), oxyethylene / oxypropylene block copolymer, sorbitan fatty acid esters (for example, sorbitan monolaurate, sorbitan monooleate, sorbitan trioleate, etc.), polyoxyethylene sorbitan fatty acid esters (for example, polyoxyethylene) Sorbitan monolaurate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitant Oleate, etc.), polyoxyethylene sorbitol fatty acid esters (eg, polyoxyethylene sorbitol tetraoleate), glycerin fatty acid esters (eg, glycerol monooleate), polyoxyethylene glycerin fatty acid esters (polyoxymonostearate) Ethylene glycerol, monooleic acid polyoxyethylene glycerin, etc.), polyoxyethylene fatty acid esters (polyethylene glycol monolaurate, polyethylene glycol monooleate, etc.), polyoxyethylene alkylamine, acetylene glycols (eg, 2, 4, 7) , 9-tetramethyl-5-decyne-4,7-diol, and ethylene oxide adducts and propylene oxide adducts of the diols), and the like. Sharp emission alkyl ethers are preferable. The nonionic surfactant can be contained in both the first coating solution and the second coating solution.

  Examples of the amphoteric surfactant include amino acid type, carboxyammonium betaine type, sulfoammonium betaine type, ammonium sulfate betaine type, imidazolium betaine type, and the like, for example, US Pat. No. 3,843,368, Those described in JP-A-59-49535, JP-A-63-236546, JP-A-5-303205, JP-A-8-262742, and JP-A-10-282619 can be suitably used. As the amphoteric surfactant, an amino acid type amphoteric surfactant is preferable, and as the amino acid type amphoteric surfactant, as described in JP-A-5-303205, for example, an amino acid (glycine, glutamic acid, Histidine acid etc.) and N-aminoacyl acids and salts thereof into which long chain acyl groups have been introduced.

Examples of the anionic surfactant include fatty acid salts (for example, sodium stearate, potassium oleate), alkyl sulfate esters (for example, sodium lauryl sulfate, triethanolamine lauryl sulfate), and sulfonates (for example, sodium dodecylbenzenesulfonate). Alkyl sulfosuccinate (for example, sodium dioctyl sulfosuccinate), alkyl diphenyl ether disulfonate, alkyl phosphate, and the like.
Examples of the cationic surfactant include alkylamine salts, quaternary ammonium salts, pyridinium salts, imidazolium salts, and the like.

  Examples of the fluorosurfactant include compounds derived via an intermediate having a perfluoroalkyl group using a method such as electrolytic fluorination, telomerization, or oligomerization. Examples thereof include perfluoroalkyl sulfonates, perfluoroalkyl carboxylates, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl trialkyl ammonium salts, perfluoroalkyl group-containing oligomers, and perfluoroalkyl phosphate esters.

  The silicone surfactant is preferably a silicone oil modified with an organic group, and can have a structure in which a side chain of a siloxane structure is modified with an organic group, a structure in which both ends are modified, or a structure in which one end is modified. Examples of the organic group modification include amino modification, polyether modification, epoxy modification, carboxyl modification, carbinol modification, alkyl modification, aralkyl modification, phenol modification, and fluorine modification.

  The content of the surfactant in the coating solution for forming the ink receiving layer is preferably 0.001 to 2.0%, more preferably 0.01 to 1.0%. Further, when coating is performed using two or more liquids as the ink receiving layer coating liquid, it is preferable to add a surfactant to each coating liquid.

  The ink receiving layer according to the present invention preferably contains a high-boiling organic solvent for preventing cracking and curling. The high-boiling organic solvent is an organic compound having a boiling point of 150 ° C. or higher at normal pressure and water-soluble or A hydrophobic compound can be contained, and it may be liquid or solid at room temperature, and may be a low molecule or a polymer.

[Inkjet recording medium and production thereof]
(Support)
As the support in the ink jet recording medium of the present invention, either a transparent support made of a transparent material such as plastic or an opaque support made of an opaque material such as paper can be used. In order to make use of the transparency of the ink receiving layer, it is preferable to use a transparent support or a highly glossy opaque support. Further, a read-only optical disk such as a CD-ROM or DVD-ROM, a write-once optical disk such as a CD-R or DVD-R, or a rewritable optical disk can be used as a support, and an ink receiving layer can be provided on the label surface side. .
Further, as the support, it is used for resin-coated paper in which a thermoplastic resin layer is provided on both surfaces of an opaque material such as paper, for example, art paper, coated paper, cast-coated paper, and a silver salt photographic support. Preferable examples include those having a thermoplastic resin layer on both surfaces of a highly glossy paper substrate such as baryta paper, and resin-coated paper used for silver salt photographic printing paper.

  Next, the resin-coated paper will be described in detail. The base paper of the resin-coated paper is made from wood pulp as a main raw material, and if necessary, paper is made using synthetic pulp such as polypropylene or synthetic fiber such as nylon or polyester in addition to wood pulp. As the wood pulp, any of LBKP, LBSP, NBKP, NBSP, LDP, NDP, LUKP, and NUKP can be used, but it is preferable to use more LBKP, NBSP, LBSP, NDP, and LDP with a large amount of short fibers. preferable. However, the ratio of LBSP and / or LDP is preferably 10% by mass or more and 70% by mass or less. The pulp is preferably a chemical pulp (sulfate pulp or sulfite pulp) with few impurities, and a pulp having a whiteness improved by bleaching is also useful.

  In the base paper, sizing agents such as higher fatty acids and alkyl ketene dimers, white pigments such as calcium carbonate, talc and titanium oxide, paper strength enhancing agents such as starch, polyacrylamide and polyvinyl alcohol, fluorescent whitening agents, polyethylene glycols A water retaining agent such as a dispersant, a softening agent such as a quaternary ammonium, and the like can be appropriately added.

The freeness of the pulp used for papermaking is preferably 200 to 500 ml as defined by CSF, and the fiber length after beating is a 24 mesh residual mass% and a 42 mesh residual as defined in JIS P-8207. 30 to 70% of the sum with the mass% of is preferable. In addition, it is preferable that the mass% of 4 mesh remainder is 20 mass% or less. The basis weight of the base paper is preferably 30 to 250 g, and particularly preferably 50 to 200 g. The thickness of the base paper is preferably 40 to 250 μm. The base paper can be given a high smoothness by calendering at the paper making stage or after paper making. The density of the base paper is generally 0.7 to 1.2 g / m ² (JIS P-8118). Furthermore, the base paper stiffness is preferably 20 to 200 g under the conditions specified in JIS P-8143.

  A surface sizing agent may be applied to the surface of the base paper. As the surface sizing agent, a sizing agent similar to the size that can be added to the base paper can be used. The pH of the base paper is preferably 5 to 9 when measured by a hot water extraction method defined in JIS P-8113.

  The surfaces on both sides of the base paper are generally coated with polyethylene. The polyethylene is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but other LLDPE, polypropylene and the like can also be used in part.

  In particular, the polyethylene layer on the side on which the ink receiving layer is formed is obtained by adding rutile or anatase type titanium oxide, fluorescent whitening agent, ultramarine to polyethylene, as is widely done in photographic paper. Those having improved whiteness and hue are preferred. Here, as a titanium oxide content, about 3-20 mass% is preferable with respect to polyethylene, and 4-13 mass% is more preferable. Although the thickness of a polyethylene layer does not have limitation in particular, 10-50 micrometers is suitable for both front and back layers. Further, an undercoat layer can be provided on the polyethylene layer in order to provide adhesion to the ink receiving layer. As the undercoat layer, aqueous polyester, gelatin and PVA are preferable. Moreover, as thickness of this undercoat layer, 0.01-5 micrometers is preferable.

  Those coated with polyethylene can be used as glossy paper, or when the polyethylene is melt-extruded and coated on the surface of the base paper, a so-called typing treatment is applied to produce a matte surface or silk A surface formed can also be used.

  A back coat layer can be provided on the support, and examples of components that can be added to the back coat layer include a white pigment, an aqueous binder, and other components. Examples of white pigments include light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, and silicic acid. Magnesium, synthetic amorphous silica, colloidal silica, colloidal alumina, pseudoboehmite, aluminum hydroxide, alumina, lithopone, zeolite, hydrohalloysite, magnesium carbonate, magnesium hydroxide, white inorganic pigments, styrene plastic pigment, acrylic plastic Examples thereof include organic pigments such as pigments, polyethylene, microcapsules, urea resins, and melamine resins.

  Examples of the aqueous binder used in the back coat layer include styrene / maleate copolymer, styrene / acrylate copolymer, polyvinyl alcohol, silanol-modified polyvinyl alcohol, starch, cationized starch, casein, gelatin, carboxy Examples thereof include water-soluble polymers such as methyl cellulose, hydroxyethyl cellulose, and polyvinyl pyrrolidone, and water-dispersible polymers such as styrene butadiene latex and acrylic emulsion. Examples of other components contained in the backcoat layer include antifoaming agents, foam suppressors, dyes, fluorescent brighteners, preservatives, and water resistance agents.

  In addition, if necessary, polyesters such as polyethylene terephthalate (PET), cellulose esters such as nitrocellulose, cellulose acetate, and cellulose acetate butyrate, polysulfone, polyphenylene oxide, polyimide, polycarbonate, polyamide, and other plastic films such as white pigment On the surface of a highly glossy film which may be contained and made opaque (surface calender treatment may be applied), or a highly glossy film containing the various paper supports, the transparent support or the white pigment, etc. Further, it may be constituted by a support provided with a polyolefin coating layer containing or not containing a white pigment. A white pigment-containing foamed polyester film (for example, foamed PET containing polyolefin fine particles and forming voids by stretching) may be applied.

  Although there is no restriction | limiting in particular as thickness of a support body, 50-300 micrometers is preferable at the point of handleability. The surface of the support may be subjected to corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet irradiation treatment, etc. in order to improve wettability and adhesion.

(Preparation of inkjet recording medium)
The ink jet recording medium of the present invention is produced by applying the ink receiving layer coating liquid to at least one of the supports to form an ink receiving layer. The ink receiving layer is preferably crosslinked and cured.
In order to crosslink and cure the ink receiving layer, a method of adding a crosslinking agent to the ink receiving layer coating solution, an adjacent layer containing a crosslinking agent adjacent to the coating layer from the ink receiving layer coating solution with or without the addition of a crosslinking agent. There is a method of providing a layer and diffusing the crosslinking agent from the adjacent layer. As the latter method, for example, a crosslinker-containing coating solution is applied to a support in advance, and an ink-receiving layer coating solution is applied thereon, or an ink-receiving layer coating solution is applied and then a crosslinking agent-containing coating solution is applied ( There are methods such as overcoating and dipping. Further, the adjacent layer can be formed (multilayer formation) simultaneously with the ink receiving layer coating solution coating layer.
In addition, the crosslinking and curing of the coating layer from the ink-receiving layer coating solution may be performed simultaneously with (1) the formation of the coating layer, or (2) during the drying of the coating layer and before the coating layer exhibits reduced-rate drying. In any case, it is preferable to carry out by applying a basic solution having a pH of 8 or higher to the coating layer. The crosslinking agent may be contained in either the ink receiving layer coating solution or the basic solution, or may be contained in both.

  The basic solution having a pH of 8 or more can contain a crosslinking agent and a mordant as necessary. The pH of the basic solution is 8 or higher, preferably 8.5 or higher, more preferably 9.0 or higher. If the pH is less than 8, the crosslinking agent does not sufficiently perform the crosslinking reaction of the water-soluble polymer contained in the ink-receiving layer coating solution, and defects such as cracks occur in the ink-receiving layer. The basic solution includes at least a basic substance (for example, ammonia, primary amines (ethylamine, polyallylamine, etc.), secondary amines (dimethylamine, triethylamine, etc.), tertiary amines (N-ethyl-N -Methylbutylamine, etc.), alkali metal or alkaline earth metal hydroxides) and / or salts of the basic substances.

  The basic solution includes, for example, ion-exchanged water, polyallylamine that is a basic compound (for example, 1 to 5%), and, if necessary, p-toluenesulfonic acid (for example, 0.5 to 3%) It can be prepared by adding ammonium chloride (for example, 0.05 to 2%) and stirring sufficiently. “%” In each composition means solid mass%.

The simultaneous application method (multilayer application method) in which the basic solution is applied simultaneously with the formation of the application layer of the ink-receiving layer application liquid in (1) is performed by, for example, an application method using an extrusion die coater or a curtain flow coater. be able to. After the simultaneous application, the formed application layer is dried. In this case, the drying is generally performed by heating the application layer at 15 to 150 ° C. for 0.5 to 10 minutes, preferably 40 to 100. It is carried out by heating at a temperature of 0.5 to 5 minutes.
When the simultaneous application is performed by, for example, an extrusion die coater, the two types of coating liquid discharged at the same time are formed in layers near the discharge port of the extrusion die coater, that is, before moving onto the support. In this state, it is coated on the support in a multilayer manner. Since the two-layer coating liquid layered before coating is likely to cause a cross-linking reaction at the interface between the two liquids when transferred to the support, the two liquids to be ejected are mixed in the vicinity of the discharge port of the extrusion die coater. As a result, thickening is likely to occur, which may hinder the application operation. Therefore, when applying simultaneously as described above, it is preferable to apply the triple layer coating simultaneously with the application of the ink receiving layer coating solution and the basic solution, with the barrier layer solution (intermediate layer solution) interposed between the two solutions. .

  The barrier layer solution can be selected without particular limitation. For example, an aqueous solution containing a trace amount of water-soluble resin, water, or the like can be given. The water-soluble resin is used in consideration of applicability for the purpose of a thickener and the like. For example, cellulose resin (for example, hydroxypropylmethylcellulose, methylcellulose, hydroxyethylmethylcellulose) And polymers such as polyvinylpyrrolidone and gelatin. The barrier layer liquid may contain a mordant.

Further, in the method of applying the basic solution during the drying of the coating layer of the ink-receiving layer coating liquid of (2) and before the coating layer exhibits reduced-rate drying, “Before showing” usually means a process for several minutes immediately after the application of the ink-receiving layer coating solution, during which the content of the solvent (dispersion medium) in the applied coating layer is in time. It shows the phenomenon of “constant rate drying” that decreases proportionally. About the time which shows this "constant rate drying", it describes in chemical engineering handbook (pages 707-712, Maruzen Co., Ltd. issue, October 25, 1980), for example.
Drying until the coating layer of the ink receiving layer coating solution shows reduced-rate drying is generally performed at 40 to 180 ° C. for 0.5 to 10 minutes (preferably 0.5 to 5 minutes). . The drying time naturally varies depending on the coating amount, but usually the above range is appropriate.

In this method, as a method for applying the ink receiving layer coating liquid, for example, a known coating method such as an extrusion die coater, an air doctor coater, a bread coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, a bar coater, etc. Can be done by.
In the case of (2) above, the application method of the basic solution to the coating layer of the ink-receiving layer coating solution is as follows: 1) a method of further applying the basic solution on the coating layer, and 2) a method such as spraying. Examples thereof include a spraying method, and 3) a method in which the support on which the coating layer is formed is immersed in a basic solution. As the coating method of 1), for example, a known coating method such as curtain flow coater, extrusion die coater, air doctor coater, bread coater, rod coater, knife coater, squeeze coater, reverse roll coater, bar coater or the like is used. be able to. However, it is preferable to use a method in which the coater does not directly contact the already formed first coating layer, such as an extrusion die coater, a curtain flow coater, a bar coater or the like.

  After the application of the basic solution, it is generally heated at 40 to 180 ° C. for 0.5 to 30 minutes, followed by drying and curing. Especially, it is preferable to heat at 40-150 degreeC for 1 to 20 minutes.

  After the ink receiving layer is formed on the support, the ink receiving layer is subjected to, for example, super calender, gloss calender, etc., and is subjected to calender treatment through the roll nip under heat and pressure, so that surface smoothness, glossiness, It is possible to improve transparency and coating strength. However, the calendar process may cause a decrease in the porosity (that is, the ink absorbability may be decreased), so it is necessary to set the conditions under which the decrease in the porosity is small.

  As roll temperature in the case of performing a calendar process, 30-150 degreeC is preferable and 40-100 degreeC is more preferable. Moreover, as a linear pressure between rolls at the time of a calendar process, 50-400 kg / cm is preferable and 100-200 kg / cm is more preferable.

  The ink receiving layer is preferably excellent in transparency. As a guide, the haze value when the ink receiving layer is formed on a transparent film is preferably 30% or less, and 20% or less. It is more preferable. The haze value can be measured with a haze meter (HGM-2DP: manufactured by Suga Test Instruments Co., Ltd.).

  A polymer fine particle dispersion may be added to a constituent layer (for example, an ink receiving layer) of the ink jet recording medium of the present invention. The polymer fine particle dispersion is used for the purpose of improving film properties such as dimensional stabilization, curling prevention, adhesion prevention, film cracking prevention and the like. The polymer fine particle dispersion is described in JP-A Nos. 62-245258, 62-1316648, and 62-110066. When a polymer fine particle dispersion having a low glass transition temperature (40 ° C. or lower) is added to the ink receiving layer, cracking and curling of the layer can be prevented. Further, even when a polymer fine particle dispersion having a high glass transition temperature is added to the back layer, curling can be prevented.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. In the following, “parts” and “%” mean “parts by mass” and “% by mass”, respectively, and “average molecular weight” and “degree of polymerization” are “weight average molecular weight” and “weight average degree of polymerization”. Represents.

[Examples 1 to 4 and Comparative Examples 1 to 5 (Manufacturing method of silica pre-dispersion, silica atomization dispersion, ink receiving layer coating liquid)]
(Example 1)
<Manufacture of silica pre-dispersion>
In 50 parts of ion-exchanged water, 0.3 part of boric acid was dissolved, and 2 parts of a cationic polymer (Chemistat 7005, manufactured by Sanyo Chemical Co., Ltd., 40% aqueous solution) was added thereto. A solution with a pH of 3.0 was obtained. While stirring this solution at a rotational speed of 9000 rpm using a dissolver (manufactured by Tokki Kikai Kogyo Co., Ltd.), gas phase method silica fine particles (Reorosil QS-30, manufactured by Tokuyama Co., Ltd., average primary particle diameter of 7 nm) were added to this solution. 10 parts were added and stirred (kneaded) for 30 minutes to obtain a pre-dispersion liquid 1.
The viscosity of the pre-dispersion was measured at a constant liquid temperature of 30 ° C. The results are shown in Table 1.

<Manufacture of silica atomized dispersion>
The silica pre-dispersion liquid 1 obtained as described above was finely dispersed using a sand mill type disperser (manufactured by Shinmaru Enterprises Co., Ltd., KD-P) to prepare a silica fine dispersion liquid 1. .

<Manufacture of ink receiving layer coating liquid>
An aqueous solution composed of the following components was added to the silica atomized dispersion 1 and stirred for 20 minutes at a rotation speed of 8000 rpm using a dissolver (manufactured by Tokki Kikai Kogyo Co., Ltd.) to obtain an ink receiving layer coating liquid 1. .
Polyvinyl alcohol 8% aqueous solution 27.8 parts (PVA124, manufactured by Kuraray Co., Ltd., saponification degree 98.5%, polymerization degree 2400)
Boric acid 0.4 parts Polyoxyethylene lauryl ether 1.2 parts (Emulgen 109P (10% aqueous solution), HLB value 13.6, manufactured by Kao Corporation)
10 parts of ion exchange water

(Example 2)
In Example 1, the pre-dispersion liquid 2 was obtained in the same manner as in Example 1 except that the cationic polymer was changed to 2 parts of the following structural formula (40% aqueous solution) (pH of the solution was 3.2). Similarly, the viscosity was measured. Further, an atomized dispersion liquid 2 was prepared in the same manner as in Example 1, and an ink receiving layer coating liquid 2 was prepared using the same. The results are shown in Table 1.

(Example 3)
In Example 1, the pre-dispersion liquid 3 was obtained in the same manner as in Example 1 except that the cationic polymer was changed to 4 parts (20% aqueous solution) having the following structural formula (pH of the solution was 2.8). Similarly, the viscosity was measured. Further, the atomized dispersion liquid 3 was prepared in the same manner as in Example 1, and the ink receiving layer coating liquid 3 was prepared using the same. The results are shown in Table 1.

Example 4
In Example 1, the cationic polymer was changed to 1 part of Charol DC902P (Daiichi Kogyo Seiyaku Co., Ltd., 51.5% aqueous solution) in the same manner as in Example 1 except that the pH of the solution was 2.9. Pre-dispersion 4 was obtained and the viscosity was measured in the same manner. Further, the atomized dispersion liquid 4 was prepared in the same manner as in Example 1, and the ink receiving layer coating liquid 4 was prepared using this. The results are shown in Table 1.

(Comparative Example 1)
In Example 1, except that boric acid was not added (pH of the solution was 3.1), a pre-dispersion liquid 5 was obtained in the same manner as in Example 1, and the viscosity was measured in the same manner. Further, the atomized dispersion liquid 5 was prepared in the same manner as in Example 1, and the ink receiving layer coating liquid 5 was prepared using the same. The results are shown in Table 1.

(Comparative Example 2)
In Example 2, except that boric acid was not added (pH of the solution was 3.4), a pre-dispersion liquid 6 was obtained in the same manner as in Example 2, and the viscosity was measured in the same manner. Further, the atomized dispersion liquid 6 was prepared in the same manner as in Example 2, and the ink receiving layer coating liquid 6 was prepared using the same. The results are shown in Table 1.

(Comparative Example 3)
In Example 3, except that boric acid was not added (pH of the solution was 3.1), a pre-dispersion liquid 7 was obtained in the same manner as in Example 3, and the viscosity was measured in the same manner. Further, the atomized dispersion liquid 7 was prepared in the same manner as in Example 3, and the ink receiving layer coating liquid 7 was prepared using this. The results are shown in Table 1.

(Comparative Example 4)
A pre-dispersion liquid 8 was obtained in the same manner as in Example 1 except that Chemistat 7005 was not added in Example 1 (pH of the solution was 3.6), and the viscosity was measured in the same manner. Further, the atomized dispersion liquid 8 was prepared in the same manner as in Example 1, and the ink receiving layer coating liquid 8 was prepared using this. The results are shown in Table 1.

(Comparative Example 5)
A pre-dispersion liquid 9 was obtained in the same manner as in Example 1 except that the pH during kneading was changed to 6 in Example 1, and the viscosity was measured in the same manner. Further, the atomized dispersion liquid 9 was prepared in the same manner as in Example 1, and the ink receiving layer coating liquid 9 was prepared using this. The results are shown in Table 1.

  As can be seen from Table 1, the silica pre-dispersions 1 to 4 of the present invention have a low viscosity. On the other hand, pre-dispersions 5 to 9 in which boric acid is not added, a cationic polymer is not added, or the pH at the time of kneading is 5 or more have a high viscosity of the silica pre-dispersion.

[Example 5 (inkjet recording medium)]
<Production of support>
Wood pulp made of LBKP was adjusted to 300 ml Canadian freeness with a disc refiner. Subsequently, to this pulp slurry, 1.3% cationic starch (CATO 304L, manufactured by NCS Japan) per an pulp, 0.145% anionic polyacrylamide (Polyaclon ST-13, manufactured by Hoshiko Chemical Co., Ltd.), alkyl ketene dimer After adding 0.285% (Size Pine K, manufactured by Araki Chemical Co., Ltd.), 0.285% epoxidized behenamide, and 0.2% polyamide polyamine epichlorohydrin (Arafix 100, manufactured by Araki Chemical Co., Ltd.) Further, an antifoaming agent was added.

The pulp slurry prepared as described above is made with a long paper machine, and the photographic emulsion coating surface of the web is pressed against a drum dryer cylinder through a dryer canvas and dried. Alcohol (KL-118, manufactured by Kuraray Co., Ltd.) was applied at 1 g / m ² , dried and calendered. The base paper was weighed at 166 g / m ² to obtain a base paper having a thickness of 160 μm.

After the corona discharge treatment was performed on the wire surface (back surface) side of the obtained base paper, high-density polyethylene was coated to a thickness of 25 μm using a melt extruder to form a resin layer consisting of a mat surface. (Hereinafter, the resin layer surface is referred to as “back surface”). The resin layer on the back side is further subjected to corona discharge treatment, and then, as an antistatic agent, aluminum oxide (alumina sol 100, manufactured by Nissan Chemical Industries, Ltd.) and colloidal silicon dioxide (Snowtex O, Nissan Chemical Industries, Ltd.) )) Was dispersed in water at a ratio (mass ratio) of 1: 2 so that the dry mass was 0.2 g / m ² .

Furthermore, after performing a corona discharge treatment on the felt surface (front surface) side on which the resin layer is not provided, anatase titanium dioxide 10%, a content of ultramarine made by Tokyo Ink Co., which is 60 mg / m ² , And a low-density polyethylene having a MFR (melt flow rate) of 3.8, in which the whitening agent “Whitefloor PSN conc” manufactured by Nippon Chemical Industry Co., Ltd. was adjusted to a content of 13 mg / m ² , Is used to melt and extrude to a thickness of 25 μm, and a high gloss thermoplastic resin layer is formed on the front side of the base paper (hereinafter, this high gloss side is referred to as “front side”), and the support. It was.

<Preparation of basic solution of pH 8 or higher>
The following components were mixed to prepare a basic solution having a pH of 8 or higher.
Boric acid (crosslinking agent) 0.65 part polyallylamine 15 parts (PAA-03 (20% aqueous solution), manufactured by Nittobo Co., Ltd .; mordant)
Ion-exchanged water 72.25 parts ammonium chloride (surface pH adjuster) 0.1 parts polyoxyethylene lauryl ether (surfactant) 10 parts (Emulgen 109P, 2% aqueous solution, HLB value 13.6, manufactured by Kao Corporation) )
Fluorosurfactant 2.0 parts (Megafac F1405 (10% aqueous solution), manufactured by Dainippon Ink & Chemicals, Inc.)

<Preparation of inkjet recording medium>
After the corona discharge treatment is applied to the front surface of the support, the ink receiving layer coating liquids 1 to 4 obtained above are respectively applied to the front surface of the support at 200 ml / m ² using an extrusion die coater. It was applied in an amount (application step), and dried with a hot air dryer at 80 ° C. (wind speed 3 to 8 m / sec) until the solid content concentration of the application layer reached 20%. This coating layer exhibited a constant rate of drying during this period. Immediately after that, it was immersed in a basic solution having a pH of 8 or more of the above composition for 30 seconds to deposit 20 g / m ² on the coating layer (step of applying a mordant solution), and further dried at 80 ° C. for 10 minutes. (Drying process). Thereby, inkjet recording media 1 to 4 of the invention provided with an ink receiving layer having a dry film thickness of 32 μm were prepared.

Claims (4)

  Method for producing silica pre-dispersion liquid when preparing coating liquid for ink-receiving layer of ink jet recording medium using silica pre-dispersion liquid obtained by pre-dispersing silica vapor-phase process silica A gas phase method silica is kneaded in the presence of a boric acid compound and a cationic polymer in a pH range of 2 or more and less than 5 to prepare a coating liquid for an ink receiving layer of an ink jet recording medium A method for producing a silica pre-dispersion liquid.   2. The method for producing a silica pre-dispersion liquid when preparing a coating liquid for an ink receiving layer of an ink jet recording medium according to claim 1, wherein the vapor phase silica has an average primary particle diameter of 5 nm to 30 nm. .   A method for producing a silica finely divided dispersion used for preparing a coating liquid for an ink-receiving layer of an ink jet recording medium, wherein vapor phase silica is prepared in the presence of a boric acid compound and a cationic polymer and has a pH of 2 or more. Manufacture of a silica atomized dispersion for use in preparing a coating liquid for an ink receiving layer of an ink jet recording medium, wherein the silica pre-dispersion obtained by kneading in a smaller range is further atomized and dispersed. Method.   A method for producing a coating liquid for an ink-receiving layer of an ink jet recording medium, comprising: a silica precursor obtained by kneading vapor phase silica in the presence of a boric acid compound and a cationic polymer and having a pH of 2 or more and less than 5. A method for producing a coating liquid for an ink receiving layer of an ink jet recording medium, comprising adding at least a water-soluble resin to a silica atomized dispersion obtained by further atomizing and dispersing the dispersion.