JP6612582B2 - Method for producing ink jet recording material - Google Patents

Description

  The present invention relates to a method for producing an inkjet recording material having high gloss and excellent ink absorbability, and improved generation of cracks and coating defects.

  As a recording material used in the inkjet recording method, an inkjet recording material having a porous ink receiving layer made of a pigment such as amorphous silica and a water-soluble binder such as polyvinyl alcohol on a support is known.

  In recent years, a recording material having a photo-like glossiness using ultrafine particles such as gas phase method silica or wet method silica pulverized to about several hundreds nm has been known. For example, JP-A-3-56552, JP-A-10-119423, JP-A-2000-2111235 and JP-A-2000-309157 are examples of using vapor phase silica, and JP-A-9-286165. JP-A-10-181190 discloses a use example of pulverized sedimentation method silica, and JP-A-2001-277712 discloses an example of use of crushed gel method silica.

  However, when the above-mentioned ultrafine inorganic fine particles are used, high gloss can be obtained, but surface defects such as wind ripples (dry unevenness) and cracks tend to occur during coating and drying. In particular, when using non-absorbing supports such as polyolefin resin-coated paper (polyolefin resin such as polyethylene laminated on both sides of the paper) or polyester film to obtain high gloss and good texture, the support is ink. Ink absorbability of the ink receiving layer provided on the support is important. Therefore, in order to increase the void ratio and void volume of the ink receiving layer, the ink receiving layer needs to be composed of a large amount of pigment and a low ratio of binder, and as a result, wind ripples and cracks occur during the application and drying of the ink receiving layer. Increasingly more likely.

  In order to prevent such surface defects, a method is known in which a coating liquid for an ink receiving layer containing a crosslinking agent is applied to a support and then dried under relatively mild conditions. For example, in JP-A-10-119423, JP-A-2000-27093, JP-A-2001-96900, etc., a boron compound such as boric acid or borate is used as a crosslinking agent for polyvinyl alcohol, and a coating solution is applied. A method is disclosed in which the coating liquid is increased in viscosity by cooling once and then dried at a relatively low temperature. However, such conventional techniques are limited in coating and drying conditions, and as a result, productivity is reduced. Moreover, the occurrence of surface defects such as cracks may become noticeable with a slight change in drying temperature.

  On the other hand, an ink jet recording material having an ink receiving layer containing acetoacetyl group-modified polyvinyl alcohol and a crosslinking agent thereof is known. For example, they are described in JP-A-63-176173, JP-A-10-157283, JP-A-2000-52646, JP-A-2000-280600, JP-A-2003-335043, and the like.

  However, acetoacetyl group-modified polyvinyl alcohol has a problem that due to its high reactivity, aggregate formation and thickening of the coating solution occur when a crosslinking agent is added. In order to avoid this problem, a method of devising a method for adding a crosslinking agent has also been proposed. For example, JP 2005-335120 A (Patent Document 1) and JP 2006-205422 A (Patent Document 2). The ink receiving layer coating liquid containing acetoacetyl group-modified polyvinyl alcohol does not contain a cross-linking agent, and is supplied by diffusing after forming a coating film from an adjacent undercoat layer, and the top coat layer contains a cross-linking agent and ink. There are disclosed a method of simultaneously applying a receiving layer coating solution and a crosslinking agent coating solution, or a method of applying a crosslinking agent coating solution after the ink receiving layer coating solution is applied and before the drying is completed.

  However, the ink jet recording material obtained by the manufacturing method as described above is sufficiently satisfactory in terms of productivity, such as cracking of the ink receiving layer and occurrence of coating defects, although extremely high gloss and excellent ink absorbability can be obtained. It was not reached.

JP-A-2005-335120 JP 2006-205422 A

  An object of the present invention is to provide a method for producing an inkjet recording material having high gloss and excellent ink absorbability, and improved generation of cracks and coating defects.

The above object of the present invention is basically achieved by the following invention.
The ink receiving layer coating solution containing polyvinyl alcohol and boric acid and its salts with inorganic fine particles and keto groups supporting lifting member on the coating, to form an ink-receiving layer by drying, the water content of the ink receiving layer is 10 wt% A cross-linking agent coating liquid containing a compound selected from polyhydrazide compounds, polyvalent metal salts, aldehydes and methylol compounds as a cross-linking agent that reacts with the keto group of polyvinyl alcohol after the following conditions are satisfied. A method for producing an ink jet recording material, comprising applying to a receptor layer.

  According to the present invention, it is possible to provide a method for producing an ink jet recording material having high gloss and excellent ink absorbability and improved generation of cracks and coating defects.

  The present invention relates to a method for producing an ink jet recording material having an ink receiving layer containing inorganic fine particles, polyvinyl alcohol having a keto group and a crosslinking agent thereof, wherein the ink receiving layer is formed using boric acid or a salt thereof as a crosslinking agent. Thereafter, a coating liquid containing a cross-linking agent that reacts with a keto group is applied to the ink receiving layer. Conventionally, a method for separating an ink receiving layer coating solution containing a polyvinyl alcohol having a keto group and a crosslinking agent coating solution containing the crosslinking agent and mixing them at the time of coating is already known. After forming an ink receiving layer by adding boric acid or a salt thereof, by applying a coating solution for a crosslinking agent that reacts with a keto group, the occurrence of cracks and coating defects was suppressed, and production stability was successfully improved. Hereafter, the manufacturing method of the inkjet recording material of this invention is demonstrated in detail.

  First, the components contained in the ink receiving layer coating solution of the present invention will be described. Examples of the inorganic fine particles contained in the ink receiving layer coating liquid include various known fine particles such as amorphous synthetic silica, alumina, alumina hydrate, calcium carbonate, magnesium carbonate, and titanium dioxide. In this respect, amorphous synthetic silica, alumina or alumina hydrate is preferred.

  Amorphous synthetic silica can be roughly classified into wet method silica, gas phase method silica, and others depending on the production method. Wet method silica is further classified into precipitation method silica, gel method silica, and sol method silica according to the production method. Precipitated silica is produced by reacting sodium silicate and sulfuric acid under alkaline conditions, and the silica particles that have grown are agglomerated and settled, and are then commercialized through the steps of filtration, washing, drying, pulverization and classification. Precipitated silica is commercially available, for example, from Tosoh Silica Co., Ltd. as a nip seal and from Tokuyama Co., Ltd. as a Toxeal. Gel silica is produced by reacting sodium silicate and sulfuric acid under acidic conditions. During the ripening, the fine particles dissolve and reprecipitate so as to bind other primary particles, so that the distinct primary particles disappear and form relatively hard aggregated particles having an internal void structure. For example, it is commercially available as nip gel from Tosoh Silica Co., Ltd. and as syloid and silo jet from Grace Japan Co., Ltd. The sol method silica is also called colloidal silica, and is obtained by heating and aging a silica sol obtained through metathesis of sodium silicate acid or the like through an ion exchange resin layer. Yes.

  Vapor phase silica is also called a dry method as opposed to a wet method, and is generally made by a flame hydrolysis method. Specifically, a method of making silicon tetrachloride by burning with hydrogen and oxygen is generally known, but silanes such as methyltrichlorosilane and trichlorosilane can be used alone or silicon tetrachloride instead of silicon tetrachloride. Can be used in a mixed state. Vapor phase silica is commercially available as Aerosil from Nippon Aerosil Co., Ltd. and QS type from Tokuyama Co., Ltd.

In the present invention, gas phase method silica can be preferably used. The average primary particle diameter of the vapor phase silica used in the present invention is preferably 30 nm or less. More preferably, an average primary particle diameter of 3 to 15 nm (especially 3 to 10 nm) and a specific surface area by the BET method of 200 m ² / g or more (preferably 250 to 500 m ² / g) are used. In addition, the average primary particle diameter referred to in the present invention is an average value obtained by taking the diameter of a circle equal to the projected area of each of 100 primary particles existing within a certain area by observation with an electron microscope as a particle diameter. It is. The BET method referred to in the present invention is one of the powder surface area measurement methods by the vapor phase adsorption method, and is a method for obtaining the total surface area, that is, the specific surface area of a 1 g sample from the adsorption isotherm. Usually, as the adsorbed gas, a large amount of nitrogen gas is used, and the method of measuring the adsorbed amount from the change in pressure or volume of the gas to be adsorbed is most often used. The most prominent expression for expressing the isotherm of multimolecular adsorption is the Brunauer, Emmett, and Teller equation, called the BET equation, which is widely used for determining the surface area. The adsorption amount is obtained based on the BET equation, and the surface area is obtained by multiplying the area occupied by one adsorbed molecule on the surface.

  As the vapor phase method silica, those dispersed in the presence of a cationic compound can be preferably used. The average secondary particle size of the vapor phase method silica is preferably 500 nm or less, more preferably 10 to 300 nm. As a dispersion method, gas phase method silica and a dispersion medium are premixed by ordinary propeller stirring, turbine type stirring, homomixer type stirring, etc., and then a media mill such as a ball mill, a bead mill, a sand grinder, a high pressure homogenizer, an ultrahigh pressure, etc. It is preferable to perform dispersion using a pressure disperser such as a homogenizer, an ultrasonic disperser, a thin film swirl disperser, or the like. The average secondary particle diameter as used in the present invention can be determined by photographing an ink receiving layer of the obtained recording material with an electron microscope. For simplicity, a laser scattering particle size distribution meter (for example, ( The number median diameter can be measured using LA920 manufactured by HORIBA, Ltd.

  In the present invention, wet process silica is also preferably used. As the wet method silica used here, precipitation method silica or gel method silica is preferable, and precipitation method silica is particularly preferable. The wet process silica particles used in the present invention are preferably wet process silica particles having an average primary particle diameter of 50 nm or less, preferably 3 to 40 nm, and an average secondary particle diameter of 500 nm or less, and more preferably an average secondary particle. It is preferable to use wet method silica fine particles having a particle diameter of 20 to 300 nm.

  The wet process silica is preferably dispersed and pulverized in the presence of a cationic compound. As a pulverization method, a wet dispersion method in which silica dispersed in an aqueous medium is mechanically pulverized can be preferably used. A preferred method for pulverizing the wet process silica fine particles used in the present invention will be described. First, silica particles and a cationic compound are mixed in a dispersion medium mainly composed of water, and at least one of dispersion devices such as a sawtooth blade type dispersion machine, a propeller blade type dispersion machine, or a rotor stator type dispersion machine is used. Use to obtain a silica pre-dispersion. If necessary, an appropriate low boiling point solvent or the like may be added to the aqueous dispersion medium. The higher the solid content concentration of the silica pre-dispersion liquid, the higher the concentration. However, when the concentration is too high, the dispersion becomes impossible. Therefore, the preferred range is 15 to 40% by mass, and more preferably 20 to 35% by mass. Next, the silica pre-dispersion is subjected to mechanical means having a stronger shearing force to pulverize the silica particles, whereby a wet process silica fine particle dispersion is obtained. As a mechanical means, a known method can be adopted, for example, a media mill such as a ball mill, a bead mill, a sand grinder, a high pressure homogenizer, a pressure disperser such as an ultra high pressure homogenizer, an ultrasonic disperser, a thin film swirl disperser, etc. Can be used.

  As the cationic compound used for the dispersion of the gas phase method silica and the wet method silica, a cationic polymer can be preferably used. As the cationic polymer, polyethyleneimine, polydiallylamine, polyallylamine, alkylamine polymer, JP-A 59-20696, JP-A 59-33176, JP-A 59-33177, JP 59-1555088, JP 60-11389, JP 60-49990, JP 60-83882, JP 60-109894, JP 62-198493 JP-A-63-49478, JP-A-63-115780, JP-A-63-280681, JP-A-1-40371, JP-A-6-234268, JP-A-7-125411 A polymer having a primary to tertiary amino group or a quaternary ammonium base described in JP-A-10-193976 It used Mashiku. In particular, diallylamine derivatives are preferably used as the cationic polymer. In terms of dispersibility and dispersion viscosity, the weight average molecular weight of these cationic polymers is preferably about 2,000 to 100,000, and particularly preferably about 2,000 to 30,000.

  As the alumina used in the present invention, γ-alumina which is a γ-type crystal of aluminum oxide is preferable, and among them, a δ group crystal is preferable. γ-alumina can make primary particles as small as about 10 nm. Usually, secondary particles of several thousand to several tens of thousands nm are pulverized with ultrasonic waves, high-pressure homogenizers, opposed collision type jet pulverizers, etc. Can be used. The average secondary particle diameter of alumina is preferably 500 nm or less, more preferably 20 to 300 nm.

The alumina hydrate used in the present invention is represented by a constitutive formula of Al ₂ O ₃ .nH ₂ O (n = 1 to 3). The alumina hydrate used in the present invention can be obtained by a known production method such as hydrolysis of aluminum alkoxide such as aluminum isopropoxide, neutralization of aluminum salt with alkali, hydrolysis of aluminate, and the like. The average secondary particle size of the alumina hydrate used in the present invention is preferably 500 nm or less, more preferably 20 to 300 nm.

  As the above-described alumina and alumina hydrate used in the present invention, those dispersed by a known dispersant such as acetic acid, lactic acid, formic acid, nitric acid and the like are preferably used.

  Two or more kinds of inorganic fine particles may be used in combination from the inorganic fine particles described above. For example, combined use of finely divided wet method silica and vapor phase method silica, combined use of finely divided wet method silica and alumina or alumina hydrate, and combined use of vapor phase method silica and alumina or alumina hydrate. It is done.

  In the present invention, a modified polyvinyl alcohol having a keto group is used as a binder for inorganic fine particles. Specific examples of the modified polyvinyl alcohol having a keto group include acetoacetyl-modified polyvinyl alcohol.

  The acetoacetyl-modified polyvinyl alcohol can be produced by a known method such as a reaction between polyvinyl alcohol and diketene. The degree of acetoacetylation is preferably from 0.1 to 20 mol%, more preferably from 1 to 15 mol%. The saponification degree is preferably 80 mol% or more, more preferably 85 mol% or more. The degree of polymerization is preferably 500 to 5000, more preferably 2000 to 4500. As such an acetoacetyl-modified polyvinyl alcohol, a commercially available product can be obtained and used, for example, commercially available as Gosennex Z series from Nippon Synthetic Chemical Industry.

  In the present invention, in addition to polyvinyl alcohol having a keto group, other known polymer binders may be used in combination. For example, cellulose derivatives such as carboxymethyl cellulose and hydroxypropyl cellulose, starch and various modified starches, gelatin and various modified gelatins, chitosan, carrageenan, casein, soy protein, polyvinyl alcohol, various modified polyvinyl alcohols, polyvinylpyrrolidone, polyacrylamide, etc. are required It can be used together depending on the situation. Furthermore, various latexes may be used in combination as the binder resin.

  When other polymer binders are used in combination, it is preferable to use a polymer binder having a high compatibility with the modified polyvinyl alcohol having a keto group in terms of surface gloss after coating, either completely or partially saponified polyvinyl alcohol, or Cationic modified polyvinyl alcohol can be preferably used in combination. In particular, those having a saponification degree of 80% or more and an average polymerization degree of 200 to 5000 can be preferably used. Moreover, it is preferable that content of another polymer binder is less than 100 mass% with respect to the polyvinyl alcohol which has a keto group.

  Examples of the cation-modified polyvinyl alcohol include a polyvinyl alcohol having a primary to tertiary amino group or a quaternary ammonium group in the main chain or side chain of polyvinyl alcohol as described in JP-A-61-10383. It is alcohol.

  Further, the content of the binder in the ink receiving layer in the invention is preferably in the range of 3 to 40% by mass, particularly preferably 5 to 30% by mass with respect to the inorganic fine particles.

  The ink receiving layer coating liquid of the present invention contains boric acid or borate as a cross-linking agent for polyvinyl alcohol having a keto group. Examples of the boric acid used in the present invention include orthoboric acid, metaboric acid, and hypoboric acid. Examples of the boric acid salt include sodium salt, potassium salt, and ammonium salt. The addition amount of boric acid or borate is preferably 0.1 to 40% by mass, more preferably 0.5 to 30% by mass with respect to polyvinyl alcohol having a keto group.

  In the present invention, a cationic polymer similar to that used for cationization of the above-mentioned amorphous synthetic silica may be further used as an additive in the ink receiving layer. The ink receiving layer may contain a water-soluble polyvalent metal compound for improving water resistance. A water-soluble aluminum compound is preferably used as the water-soluble polyvalent metal compound.

  As the water-soluble aluminum compound, for example, as the inorganic salt, aluminum chloride or its hydrate, aluminum sulfate or its hydrate, ammonium alum and the like are known. Furthermore, a basic polyaluminum hydroxide compound which is an inorganic aluminum-containing cationic polymer is known.

Among these water-soluble aluminum compounds, those that can be stably added to the coating solution for forming the ink receiving layer are preferable, and a basic polyaluminum hydroxide compound is preferably used. The main component of this compound is represented by the following formula 1, 2 or 3, for example, [Al ₆ (OH) ₁₅ ] ³⁺ , [Al ₈ (OH) ₂₀ ] ⁴⁺ , [Al ₁₃ (OH) ₃₄ ] ⁵⁺ , It is a water-soluble polyaluminum hydroxide that stably contains a basic and high-molecular polynuclear condensed ion such as [Al ₂₁ (OH) ₆₀ ] ³⁺ .

[Al ₂ (OH) _n Cl _6-n ] _m ·· Formula 1
[Al (OH) ₃ ] _n AlCl ₃ .. Formula 2
Al _n (OH) _m Cl _(3n−m) 0 <m <3n Formula 3

  These are water treatment agents in the name of polyaluminum chloride (PAC) from Taki Chemical Co., Ltd., in the name of polyaluminum hydroxide (Paho) from Asada Chemical Industry Co., Ltd., and Riken Co., Ltd. It is commercially available from Green under the name of Purachem WT and from other manufacturers for the same purpose, and various grades are readily available. In the present invention, these commercially available products can be used as they are.

  The content of the water-soluble polyvalent metal compound is preferably in the range of 0.1 to 10% by mass with respect to the inorganic fine particles contained in the ink receiving layer.

  The ink receiving layer further includes coloring dyes, coloring pigments, ultraviolet absorbers, antioxidants, pigment dispersants, antifoaming agents, leveling agents, preservatives, fluorescent whitening agents, viscosity stabilizers, pH adjusting agents, etc. Various known additives can also be added. Further, the pH of the coating solution for the ink receiving layer of the present invention is preferably in the range of 3.3 to 6.5, particularly preferably in the range of 3.5 to 5.5.

  Further, the preservability after printing can be improved by incorporating a thioether compound, carbohydrazide and derivatives thereof in the ink receiving layer.

  The carbohydrazide derivative used in the present invention may be a compound having one or more of the same structure in the same molecule, or a polymer having the same structure in the molecular main chain or side chain.

  Examples of the thioether compound used in the present invention include an aromatic thioether compound in which an aromatic group is bonded on both sides of a sulfur atom, and an aliphatic thioether compound having an alkyl group on both sides of the sulfur atom. Among these, an aliphatic thioether compound having a hydrophilic group is particularly preferable.

  These compounds can be synthesized with reference to known synthesis methods and the synthesis methods described in JP-A Nos. 2002-321447 and 2003-48372. Moreover, about some compounds, a commercially available chemical product can be used as it is.

In the present invention, the solid content coating amount of the ink receiving layer is preferably from 10 to 60 g / ^{m 2,} when the support is a resin-coated paper is preferably 20 to 60 g / ^{m 2.}

  In the present invention, the coating method of the ink receiving layer is not particularly limited, and a known coating method can be used. For example, there are a slide bead method, a curtain method, an extrusion method, an air knife method, a roll coating method, a rod bar coating method, and the like.

  Next, components contained in the crosslinking agent coating solution will be described. The following compounds are mentioned as a crosslinking agent which reacts with the keto group which the polyvinyl alcohol of this invention has.

(1) Polyamines Aliphatic polyamines;
Alkylene diamines (for example, ethylene diamine, propylene diamine, trimethylene diamine, tetramethylene diamine, hexamethylene diamine, etc.).
-Polyalkylene polyamines (for example, diethylenetriamine, iminobis (propylamine), bis (hexamethylene) triamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, etc.).
-These alkyl or hydroxyalkyl substituents (for example, aminoethylethanolamine, methyliminobis (propylamine), etc.).
-Alicyclic or heterocyclic-containing aliphatic polyamines such as 3,9-bis (3-aminopropyl) -2,4,8,10-tetraoxaspiro [5,5] undecane.
-Aromatic ring-containing aliphatic amines (for example, xylylenediamine, tetrachloro-p-xylylenediamine, etc.).

C4-C15 alicyclic polyamines;
For example, 1,3-diaminocyclohexane, isophorone diamine, menthane diamine, 4,4'-methylene dicyclohexane diamine (hydrogenated methylene dianiline) and the like.

A C4-C15 heterocyclic polyamine;
For example, piperazine, N-aminoethylpiperazine, 1,4-diaminopiperazine and the like.

C6-C20 aromatic polyamines;
Unsubstituted aromatic polyamines (eg 1,2-, 1,3- and 1,4-phenylenediamine, 2,4'- and 4,4'-diphenylmethanediamine, polyphenylpolymethylenepolyamine, diaminodiphenylsulfone, benzidine Thiodianiline, bis (3,4-diaminophenyl) sulfone, 2,6-diaminopyridine, m-aminobenzylamine, triphenylmethane-4,4 ′, 4 ″ -triamine, naphthylenediamine and the like.
Aromatic polyamines having a nucleus-substituted alkyl group (for example, a C1-C4 alkyl group) (for example, 2,4- and 2,6-tolylenediamine, crude tolylenediamine, diethyltolylenediamine, 4,4'- Diamino-3,3'-dimethyldiphenylmethane, 4,4'-bis (o-toluidine), dianisidine, diaminoditolylsulfone, 1,3-dimethyl-2,4-diaminobenzene, 1,3-diethyl-2, 4-diaminobenzene, 1,3-dimethyl-2,6-diaminobenzene, 1,4-diethyl-2,5-diaminobenzene, 1,4-diisopropyl-2,5-diaminobenzene, 1,4-dibutyl- 2,5-diaminobenzene, 2,4-diaminomesitylene, 1,3,5-triethyl-2,4-diaminobenzene, 1,3,5- Riisopropyl-2,4-diaminobenzene, 1-methyl-3,5-diethyl-2,4-diaminobenzene, 1-methyl-3,5-diethyl-2,6-diaminobenzene, 2,3-dimethyl- 1,4-diaminonaphthalene, 2,6-dimethyl-1,5-diaminonaphthalene, 2,6-diisopropyl-1,5-diaminonaphthalene, 2,6-dibutyl-1,5-diaminonaphthalene, 3,3 ′ , 5,5'-tetramethylbenzidine, 3,3 ', 5,5'-tetraisopropylbenzidine, 3,3', 5,5'-tetramethyl-4,4'-diaminodiphenylmethane, 3,3 ', 5,5′-tetraethyl-4,4′-diaminodiphenylmethane, 3,3 ′, 5,5′-tetraisopropyl-4,4′-diaminodiphenylmethane, 3,3 ′, , 5'-tetrabutyl-4,4'-diaminodiphenylmethane, 3,5-diethyl-3'-methyl-2 ', 4-diaminodiphenylmethane, 3,5-diisopropyl-3'-methyl-2', 4-diamino Diphenylmethane, 3,3'-diethyl-2,2'-diaminodiphenylmethane, 3,3 ', 5,5'-tetraethyl-4,4'-diaminobenzophenone, 3,3', 5,5'-tetraisopropyl- 4,4'-diaminobenzophenone, 3,3 ', 5,5'-tetraethyl-4,4'-diaminodiphenyl ether, 3,3', 5,5'-tetraisopropyl-4,4'-diaminodiphenyl sulfone, etc. ).

Polyamide polyamines;
For example, low molecular weight (for example, molecular weight 200 to 5000) obtained by condensation of dicarboxylic acid (such as dimer acid) and excess (more than 2 moles per mole of acid) polyamines: (such as alkylenediamine, polyalkylenepolyamine, etc.) Polyamide polyamine etc.

Polyether polyamines;
For example, a hydride of a cyanoethylated polyether polyol (polyalkylene glycol, etc.) having a molecular weight of 100 to 5000.

(2) Dicyandiamide derivative;
Dicyandiamide, dicyandiamide / formalin polycondensate, dicyandiamide / diethylenetriamine polycondensate, etc.

(3) a hydrazine compound;
Inorganic salts of hydrazine, monoalkyl hydrazine, hydrazine (eg, inorganic salts such as hydrochloric acid, sulfuric acid, nitric acid, nitrous acid, phosphoric acid, thiocyanic acid, carbonic acid), organic salts of hydrazine (eg, organic salts such as formic acid, oxalic acid, etc.) ).

(4) polyhydrazide compounds (dihydrazide, trihydrazide);
Carbohydrazide, succinic acid dihydrazide, adipic acid dihydrazide, citric acid trihydrazide, sebacic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide and the like.

(5) Aldehydes;
Monoaldehyde such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, crotonaldehyde, benzaldehyde, glyoxal, malondialdehyde, succindialdehyde, glutardialdehyde, maleindialdehyde, 1,8-octane dial, phthalaldehyde, isophthalaldehyde , Terephthalaldehyde, dialdehydes such as aldehyde-terminated PVA, side chain aldehyde-containing copolymer obtained by saponifying arylidene acetate vinyl diacetate copolymer, dialdehyde starch, polyacrolein and the like.

(6) methylol compounds;
Methylolphosphine, dimethylolurea, dimethylolmelamine, trimethylolmelamine, urea resin initial polymer, melamine resin initial polymer, and the like.

(7) an activated vinyl compound;
Divinyl sulfone compounds, β-hydroxyethyl sulfone compounds, and the like.

(8) epoxy compound;
Epichlorohydrin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin di or triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, diglycidyl amine, polyepoxy compounds, etc. .

(9) Isocyanate compounds;
Tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylolpropane-tolylene diisocyanate adduct, triphenylmethane triisocyanate, methylenebis-4-phenylmethane triisocyanate, isophorone diisocyanate, and their ketoxime block or phenol block, poly An isocyanate etc. are mentioned.

(10) phenolic compounds;
Phenol resin initial condensate, resorcinol resin, etc.

(11) a polyvalent metal salt;
-Zirconium salts (zirconium nitrate, basic zirconium carbonate, zirconium acetate, zirconium sulfate, zirconium oxychloride, zirconium chloride, zirconium zirconium chloride, zirconium carbonate, ammonium zirconium carbonate, potassium zirconium carbonate, zirconium fluoride compound, etc.).
-Titanium salts (titanium tetrachloride, titanium lactate, tetraisopropyl titanate, etc.).
-Aluminum salt (aluminum chloride, aluminum sulfate, aluminum lactate, etc.).
・ Calcium salts (calcium chloride, calcium sulfate, calcium acetate, calcium propionate, etc.).
-Magnesium salts (magnesium chloride, magnesium sulfate, etc.).
・ Zinc salts (zinc chloride, zinc sulfate, zinc acetate, etc.).

  As the cross-linking agent used in the present invention, polyhydrazide compounds, polyamines, polyvalent metal salts, aldehydes, methylol compounds, epoxy compounds, dicyandiamide derivatives, and isocyanate compounds are preferable, and in particular, polyhydrazide compounds and polyvalent metal salts. Aldehydes and methylol compounds are preferred.

  Among the polyhydrazide compounds, dihydrazide compounds are particularly preferable, and adipic acid dihydrazide and succinic acid dihydrazide are more preferable. Among the above polyvalent metal salts, a zirconium salt is particularly preferable, and zirconium oxychloride, zirconium nitrate, ammonium zirconium carbonate, and potassium zirconium carbonate are more preferable. The amount of the crosslinking agent added to the ink receiving layer by the crosslinking agent coating solution is preferably 0.1 to 50% by mass, more preferably 1 to 20% by mass with respect to the polyvinyl alcohol having a keto group in the ink receiving layer. preferable.

  In addition to the crosslinking agent, the crosslinking agent coating solution may contain a surfactant, a hydrophilic binder, inorganic fine particles, and the like.

  In the present invention, the crosslinking agent coating solution is applied after the ink receiving layer is formed. In the present invention, “after forming the ink receiving layer” refers to a state where the ink receiving layer coating liquid is applied and dried and the water content of the ink receiving layer is 10% by mass or less. As means for applying the crosslinking agent coating solution, a sliding bead method, a curtain method, an extrusion method, a slot die method, a gravure roll method, an air knife method, a blade coating method, a rod bar coating method, and the like are suitable, Since the wet coating amount of the crosslinking agent coating liquid is preferably not more than the void volume of the ink receiving layer, a slide bead method, which is a method of applying a coating liquid that has been measured in advance so as to have a predetermined coating amount, A curtain method, an extrusion method, a slot die method, a gravure roll method, and the like are preferable. Among these, the gravure roll method is particularly preferable from the viewpoint of the amount of shearing force applied to the crosslinking agent coating solution.

  Examples of the support for the inkjet recording material of the present invention include high-quality paper, art paper, coated paper, cast coated paper, and resin-coated paper in which at least one surface of a base paper is coated with a resin. From the viewpoint, a resin-coated paper is preferable, and a polyolefin resin-coated paper in which at least one surface of the base paper is coated with a polyolefin resin layer is particularly preferable. The thickness of these supports is 50 to 300 μm, preferably 80 to 260 μm.

  The polyolefin resin-coated paper support (hereinafter referred to as polyolefin resin-coated paper) that is preferably used in the present invention will be described in detail. The water content of the polyolefin resin-coated paper used in the present invention is not particularly limited, but is preferably in the range of 5.0 to 9.0% by mass, more preferably 6.0 to 9.0% by mass, due to curling properties. % Range. The moisture content of the polyolefin resin-coated paper can be measured using any moisture measuring method. For example, an infrared moisture meter, an absolute dry weight method, a dielectric constant method, a Karl Fischer method, or the like can be used.

  The base paper constituting the polyolefin resin-coated paper is not particularly limited, and commonly used paper can be used. However, for example, a smooth base paper used for a photographic support is preferable. As the pulp constituting the base paper, natural pulp, regenerated pulp, synthetic pulp or the like is used alone or in combination. This base paper is blended with additives such as sizing agent, paper strength enhancer, filler, antistatic agent, fluorescent whitening agent, and dye generally used in papermaking.

  Further, a surface sizing agent, a surface paper strength agent, a fluorescent brightening agent, an antistatic agent, a dye, an anchor agent, and the like may be applied on the surface.

Further, the thickness of the base paper is not particularly limited, but preferably has a good surface smoothness such as a paper that is compressed during or after paper making by applying pressure with a calender or the like, and the basis weight thereof is 30 to 250 g. / M ² is preferred.

  Examples of the polyolefin resin that coats the base paper include olefin homopolymers such as low density polyethylene, high density polyethylene, polypropylene, polybutene, and polypentene, or copolymers comprising two or more olefins such as ethylene-propylene copolymer, and the like. Of various densities and melt viscosity indices (melt index) can be used alone or as a mixture thereof.

  In addition, in the resin of polyolefin resin-coated paper, white pigments such as titanium dioxide, zinc oxide, talc and calcium carbonate, fatty acid amides such as stearic acid amide and arachidic acid amide, zinc stearate, calcium stearate, aluminum stearate, Fatty acid metal salts such as magnesium stearate, antioxidants such as hindered phenol compounds, blue pigments and dyes such as cobalt blue, ultramarine blue, cecilian blue, phthalocyanine blue, magenta such as cobalt violet, fast violet, manganese purple It is preferable to add various additives such as pigments, dyes, fluorescent brighteners and ultraviolet absorbers in appropriate combinations.

  As a main method for producing a polyolefin resin-coated paper, it is produced by a so-called extrusion coating method in which a polyolefin resin is cast on a traveling base paper in a heated and melted state, and both surfaces of the base paper are coated with the resin. Further, before the resin is coated on the base paper, the base paper is preferably subjected to an activation treatment such as corona discharge treatment or flame treatment. The thickness of the resin coating layer is suitably 5 to 50 μm.

The side of the support used in the present invention on which the ink receiving layer is coated preferably has an undercoat layer. This undercoat layer is applied and dried in advance on the surface of the support before the ink receiving layer is applied. The undercoat layer mainly contains a water-soluble polymer or polymer latex that can form a film. Preferred are water-soluble polymers such as gelatin, polyvinyl alcohol, polyvinyl pyrrolidone and water-soluble cellulose, and particularly preferred is gelatin. Adhesion amount of the water-soluble polymer is preferably ^{10~500mg / m 2, 20~300mg / m} 2 is more preferable. Further, the undercoat layer preferably contains a surfactant and a hardener. By providing the undercoat layer on the support, it effectively works to prevent cracking when the ink receiving layer is applied, and a uniform coated surface is obtained.

  Various types of backs are provided on the ink-absorbing side of the ink jet recording material of the present invention on the side opposite to the support to prevent curling and to further improve the adhesion and ink transfer when superimposed immediately after printing. A layer may be provided.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, the content of this invention is not restricted to an Example. Parts and% are based on mass.

Example 1
<Preparation of polyolefin resin-coated paper 1>
A 1: 1 mixture of hardwood bleached kraft pulp (LBKP) and hardwood bleached sulfite pulp (LBSP) was beaten to 300 ml with Canadian Standard Freeness to prepare a pulp slurry. As a sizing agent, alkylketene dimer is 0.5% to pulp, polyacrylamide is 1.0% to pulp, and cationized starch is 2.0% to pulp. Polyamide epichlorohydrin resin is 0 to pulp. 0.5% added and diluted with water to give a 0.2% slurry. This slurry was made with a long paper machine to a basis weight of 170 g / m ² , dried and conditioned to obtain a polyolefin resin-coated paper base paper. A polyethylene resin composition in which 10% anatase-type titanium is uniformly dispersed in a low density polyethylene resin having a density of 0.918 g / cm ³ is melted at 320 ° C. to a paper base having a density of 35 μm. The surface was extrusion-coated using a cooling roll that had been extrusion-coated as described above and fine-roughened. Melted at similarly 320 ° C. The blend resin composition of the low density polyethylene resin 30 parts of a density 0.962 g / cm 70 parts high density polyethylene resin of ³ and a density 0.918 g / cm ³ on the other surface, the thickness Extrusion-coating to a thickness of 30 μm, and extrusion coating using a cooling roll having a roughened surface was used as the back surface.

The surface of the polyolefin resin-coated paper was subjected to a high-frequency corona discharge treatment, and then an undercoat layer having the following composition was applied and dried so that gelatin was 50 mg / m ² to prepare a support.

<Underlayer>
Lime-processed gelatin 100 parts Sulfosuccinic acid-2-ethylhexyl ester salt 2 parts Chromium alum 10 parts

On the surface provided with the undercoat layer of the polyolefin resin-coated paper prepared as described above, the ink receiving layer coating solution 1 having the following composition was applied by a slide bead coater so that the dry coating amount was 25 g / m ² . Then, after cooling at 10 ° C. for 20 seconds, heated air of 30 to 55 ° C. was blown and dried. After drying, the water content of the ink receiving layer was 5% by mass. Furthermore, the crosslinking agent coating liquid 1 having the following composition was coated with a coating apparatus using a slanted gravure roll, dried by blowing hot air of 45 ° C., and the inkjet recording material of Example 1 was obtained. The wet coating amount of the crosslinking agent coating solution was adjusted to 20 ml / m ² (0.24 g / m ^{2 in} terms of solid content) by adjusting the rotational speed of the oblique gravure roll.

<Preparation of gas phase method silica dispersion 1>
After adding 4 parts of dimethyldiallylammonium chloride homopolymer (molecular weight 9000) and 100 parts of vapor phase method silica (average primary particle size 7 nm, specific surface area 300 m ² / g by BET method) to water, a preliminary dispersion was prepared, and then high pressure A gas phase method silica dispersion having a solid content concentration of 20% was prepared by a homogenizer treatment. The average secondary particle diameter of the vapor phase method silica was 135 nm.

<Ink-receiving layer coating solution 1>
Gas phase silica dispersion 1 (as solid content of gas phase method silica) 100 parts Boric acid 4 parts Acetoacetyl-modified polyvinyl alcohol 25 parts (Gosenx Z-410, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
14% solid content of coating solution

<Crosslinking agent coating solution 1>
Adipic acid dihydrazide coating solution solids content 1.2%

(Example 2)
An ink jet recording material of Example 2 was obtained in the same manner as in Example 1 except that the crosslinking agent coating solution 1 of Example 1 was changed to the following crosslinking agent coating solution 2.

<Crosslinking agent coating solution 2>
Zirconium ammonium carbonate (Zircozol AC-7, manufactured by Daiichi Elemental Chemical Co., Ltd.)
Solid content concentration of coating liquid 1.2%

(Comparative Example 1)
An ink jet recording material of Comparative Example 1 was obtained in the same manner as in Example 1 except that the ink receiving layer coating liquid 1 of Example 1 was changed to the following ink receiving layer coating liquid 2.

<Ink-receiving layer coating solution 2>
Gas phase silica dispersion 1 (as solid phase of gas phase method silica) 100 parts Acetacetyl-modified polyvinyl alcohol 25 parts (Gosenx Z-410, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
14% solid content of coating solution

(Comparative Example 2)
The ink-receiving layer coating solution 2 and the following crosslinking agent coating solution 3 are applied by a slide bead coater so that the crosslinking agent coating solution 3 is an upper layer, and dried in the same manner as in Example 1 to perform inkjet recording of Comparative Example 2. Obtained material. At this time, ^{25 g} / m 2 as respective coating amount of the ink receiving layer coating solution and a crosslinking agent coating liquid drying coating amount was 0.24 g / ^{m 2.}

<Crosslinking agent coating solution 3>
Adipic acid dihydrazide 100 parts Nonionic surfactant 2 parts Solid content concentration of coating solution 1.2%

(Comparative Example 3)
An ink jet recording material of Comparative Example 3 was obtained in the same manner as in Example 1 except that the ink receiving layer coating liquid 1 and the crosslinking agent coating liquid 1 were mixed immediately before coating in Example 1 and coated with a slide bead coater.

  The ink jet recording material produced as described above was evaluated as follows. The results are shown in Table 1. Note that all of the produced inkjet recording materials had high gloss and excellent ink absorbability.

<Cracks on the coated surface>
The coated surface of the recording material was observed and evaluated according to the following criteria.
○: No cracks at all.
Δ: Slight cracking is observed.
X: The occurrence of cracks is clearly recognized.

<Coating defects>
Of the coating defects of 3 mm or more present in 10 m ^{2 of the} recording material, the frequency of coating liquid aggregates was visually evaluated and evaluated according to the following criteria.
○: Less than 5.
Δ: 5 or more and less than 20
X: 20 or more.

  From the results in Table 1, it can be seen that the ink jet recording material produced by the method of the present invention has high gloss and excellent ink absorbency, and the occurrence of cracks and coating defects is improved.

Claims (1)

An ink receiving layer is formed by applying and drying an ink receiving layer coating solution containing inorganic fine particles, polyvinyl alcohol having a keto group and boric acid or a salt thereof on a support, and the water content of the ink receiving layer is 10% by mass or less. Then, a coating solution for a crosslinking agent containing a compound selected from a polyhydrazide compound, a polyvalent metal salt, an aldehyde, and a methylol compound as a crosslinking agent that reacts with the keto group of polyvinyl alcohol is obtained. A method for producing an ink jet recording material, comprising applying to a layer.