JP2009143127A - Inkjet recording medium for pigment ink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording medium for pigment ink which keeps bronze suppressed, and is excellent in glossiness and scratch resistance. <P>SOLUTION: This inkjet recording medium for pigment ink has at least one layer of an ink accepting layer containing a pigment and a binder on a supporting body. On the outermost surface layer which is farthest from the supporting body of the ink accepting layer, at least one kind of water-soluble comb type structure polymers is made to contain. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inkjet recording medium for pigment ink.

Ink-jet recording methods have been widely used in view of being capable of recording on various recording materials, relatively inexpensive hardware (devices), compact and excellent in quietness. With so-called high resolution recording of ink jet printers, development of hardware (devices), and various developments of ink jet recording media, so-called photographic-like high-quality recorded matter can be obtained.
In general, an ink jet recording method using a pigment ink is considered to be superior in storage stability compared to an ink jet recording method using a dye ink. However, it is known that the ink jet recording method using pigment ink may cause other problems such as the phenomenon that bronze, which is different from the original color of pigment, occurs on the surface, the glossiness is lowered, and the abrasion resistance is deteriorated. ing. As a method for solving such a problem, an ink jet recording method in which heating and pressurizing is performed after image formation is known (for example, see Patent Document 1).
Further, as a method for solving the deterioration of scratch resistance without requiring heat and pressure treatment, a method of incorporating a polymer resin contained in a pigment ink into an ink receiving layer is known (for example, see Patent Document 2). ).
JP 2004-181803 A JP 2003-72230 A

However, in the method described in Patent Document 1, the inkjet recording system and the printing process are complicated, and there are problems in terms of cost and the like. Further, the method described in Patent Document 2 is insufficient in terms of suppressing bronze and improving glossiness.
An object of the present invention is to provide an ink jet recording medium for pigment ink, which is suppressed in bronze and has good gloss and scratch resistance.

Specific means for solving the above problems are as follows.
<1> The support has at least one ink receiving layer containing a pigment and a binder, and the outermost surface layer farthest from the support of the ink receiving layer contains at least one water-soluble comb-type structural polymer. An ink jet recording medium for pigment ink.
<2> The water-soluble comb-type structure polymer is a co-polymer comprising (a) an ethylenically unsaturated 1,2-dicarboxylic acid derivative, (b) an unsaturated monocarboxylic acid derivative, and (c) a polyalkyleneoxyallyl ether. And a reaction product of at least one selected from the group consisting of ammonia, amine, water, alcohol, amino alcohol, alkali metal hydroxide, and alkaline earth metal hydroxide, and a copolymer. The ink jet recording medium for pigment ink according to <1>, wherein the ink jet recording medium is one type.

  According to the present invention, it is possible to provide an ink jet recording medium for pigment ink that is suppressed in bronze and has excellent gloss and scratch resistance.

  The inkjet recording medium for pigment ink of the present invention has at least one ink receiving layer containing a pigment and a binder on a support, and at least the outermost surface layer farthest from the support of the ink receiving layer, It contains at least one water-soluble comb structure polymer. By using the inkjet recording medium for pigment ink having such a configuration, the occurrence of bronzing can be suppressed without performing heat and pressure treatment after inkjet recording, good glossiness can be obtained, and scratch resistance can be improved.

[Water-soluble comb structure polymer]
Examples of the water-soluble comb-type structure polymer in the present invention include JP 2003-140330 A, Progress in Organic Coating 45, 83-93 (2002), Internet URL <http://www.byk.co.jp/ Polymer molecules as described in technical / literature / pdf / 060428.pdf>, <http://www.byk.co.jp/technical/literature/pdf/060519.pdf>, adsorbed to pigments Means a water-soluble polymer having a structure capable of functioning as a pigment dispersant, and having an adsorbing part that solvates with a solvent and stabilizes the dispersibility of the pigment in the polymer molecule. The water-soluble comb structure polymer is, for example, adsorbed in a planar shape on the surface of the pigment by a plurality of adsorption portions, and a plurality of polymer chains constituting the solvation portion are extended from the pigment surface into a comb shape. Good pigment dispersibility can be exhibited.

  The adsorption part is made of, for example, a hydrophobic polymer. The hydrophobic polymer is not particularly limited as long as it has a hydrophobic partial structure and can be adsorbed to a pigment. Specific examples include polymers having a structure such as polyalkylene and polystyrene.

  In the present invention, the adsorbing part preferably contains at least one selected from an amino group, a phosphoric acid group, and a carboxy group in addition to the hydrophobic polymer from the viewpoint of adsorption stability to the pigment, and includes a carboxy group. It is more preferable. Furthermore, the carboxy group is more preferably a carboxy group derived from a monomer having a monocarboxylic acid or a monomer having a dicarboxylic acid from the viewpoint of adsorption stability to the pigment, and is derived from a monomer having a monocarboxylic acid. It is particularly preferred to have at least two carboxy groups derived from a monomer having a carboxy group and a dicarboxylic acid.

  The solvation part is composed of, for example, a hydrophilic polymer. The hydrophilic polymer is not particularly limited as long as it has a hydrophilic group and can be solvated with a solvent. Specifically, from the viewpoint of suppressing pigment ink aggregation, it is preferably at least one selected from polyacrylic acid derivatives, polyester derivatives, polyurethane derivatives, and polyether derivatives, and at least one of polyurethane derivatives and polyether derivatives. It is more preferable that it is at least one kind of polyether derivative.

The hydrophilic polymer constituting the solvation part suppresses aggregation of pigment inks after printing, and the number of atoms in the polymer main chain is 10 from the viewpoint of suppression of bronze, improvement of gloss, and improvement of scratch resistance. It is preferable that it is -450, It is more preferable that it is 50-400, It is especially preferable that it is 100-350.
By setting the number of atoms in the polymer main chain to 10 or more, the steric hindrance effect becomes strong, and a sufficient pigment aggregation suppressing effect can be obtained. Further, when the number of atoms of the polymer main chain is 450 or less, the polymer molecular weight does not become too large, the diffusibility becomes good, and the pigment aggregation suppressing effect is sufficiently obtained.

  The respective monomer contents constituting the adsorbing part and solvating part of the water-soluble comb structure polymer in the present invention are 10 mol% to 99 mol% and 1 mol% to 90 mol%, respectively, with respect to the whole polymer molecule. It is preferably 40 mol% to 95 mol% and more preferably 5 mol% to 60 mol%, and particularly preferably 60 mol% to 90 mol% and 10 mol% to 40 mol%. By making the content of the monomer constituting the solvation part 1 mol% or more, the steric hindrance effect is strengthened, and a sufficient aggregation suppressing effect of the pigment is obtained, suppressing bronzing, improving glossiness, and improving scratch resistance. A sufficient effect is obtained. In addition, by setting the content of the monomer constituting the solvation part to 90 mol% or less, the affinity for the pigment surface is increased, and the effect of suppressing bronzing, improving glossiness, and improving scratch resistance is sufficient. can get.

  In the present invention, the water-soluble comb-type structure polymer contains (a) an ethylenically unsaturated 1,2-dicarboxylic acid derivative, (b) a non-reactive compound from the viewpoints of suppressing bronze, improving glossiness, and improving scratch resistance. A copolymer comprising a saturated monocarboxylic acid derivative, and (c) a polyalkyleneoxyallyl ether, and the copolymer and ammonia, amine, water, alcohol, aminoalcohol, alkali metal hydroxide, and alkaline earth metal hydroxide It is preferable that it is at least 1 sort (s) chosen from the group which consists of one reaction product chosen from these.

(A) Ethylenically unsaturated 1,2-dicarboxylic acid derivative The ethylenically unsaturated 1,2-dicarboxylic acid compound in the present invention (hereinafter sometimes referred to as “monomer (a)”) has 4 to 8 carbon atoms. An ethylenically unsaturated 1,2-dicarboxylic anhydride is preferred, and maleic anhydride is particularly preferred.

  In the present invention, such as maleic acid, fumaric acid, itaconic acid, mesaconic acid and citraconic acid in place of or in combination with ethylenically unsaturated 1,2-dicarboxylic acid anhydride having 4 to 8 carbon atoms. 1,2-dicarboxylic acid monoesters or diesters can be used. The alcohol constituting the ester is preferably a linear or branched alcohol having 1 to 30 carbon atoms, and the alcohol further has at least one of an alicyclic group, an aromatic group, and an aliphatic group if desired. You may do it. The alcohol suitable for the present invention includes an alkylene oxide adduct having 1 to 4 carbon atoms of the alcohol. For example, 2-butoxyethanol, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, 2-phenoxyethanol or 2- (2-phenoxyethoxy) ethanol can be used.

  Examples of the ester derivatives of ethylenically unsaturated 1,2-dicarboxylic acid include, for example, maleic acid monobutyl ester, maleic acid dibutyl ester, maleic acid monooctadecyl ester, maleic acid monooctadecyl triethyleneoxy ester, maleic acid dimethyl ester, Mention may be made of maleic acid di-2-ethylhexyl ester, fumaric acid di-2-ethylhexyl ester, maleic acid diisotridecyl ester and fumaric acid dioctadecyl ester.

Furthermore, examples of the monomer (a) may include monoamides, diamides and imides of a single amount of ethylenically unsaturated 1,2-dicarboxylic acid derivatives including maleic acid, fumaric acid, itaconic acid, mesaconic acid and citraconic acid. it can. These compounds can be composed of an ethylenically unsaturated 1,2-dicarboxylic acid derivative and a primary amine, a secondary amine, an amino alcohol having 1 to 20 carbon atoms, and at least one of ammonia. .
Specific examples of these compounds include, for example, N-cyclohexylmaleic acid amide, N-octadecenylmaleic acid amide, N, N'-dibutylmaleic acid amide, N-benzylmaleic acid amide and N, N'- And diisotridecylmaleic acid amide.

  Monomers (a) can be used alone or in combination of two or more different monomers (a). The content of the monomer (a) in the water-soluble comb structure polymer is 1 to 80 mol%, preferably 5 to 75 mol%, more preferably 20 to 70 mol%, still more preferably 40 to 65 mol. %. Adsorption to the pigment in the pigment ink can be strengthened by setting the content of the monomer (a) to 1 mol% or more. Moreover, the aggregation suppression property of a pigment improves by setting it as 80 mol% or less. As a result, bronzing is more effectively suppressed, and glossiness and scratch resistance are improved.

(B) Unsaturated monocarboxylic acid derivative The (b) unsaturated monocarboxylic acid derivative (hereinafter sometimes referred to as “monomer (b)”) in the present invention is an unsaturated monocarboxylic acid derivative having 12 to 30 carbon atoms. It is preferable that As the monomer (b), for example, synthetic and naturally-derived unsaturated monocarboxylic acids having 12 to 30 carbon atoms and derivatives thereof can be used. In particular, an unsaturated monocarboxylic acid having 12 to 30 carbon atoms having one or more carbon-carbon double bonds and derived from a natural product is preferable.

  Specifically, palmitoleic acid (for example, derived from marine animals and seed oil), oleic acid (for example, derived from coconut oil), elaidic acid, cis-vaccenic acid, linoleic acid (for example, vegetable oil) ), Α- and γ-linolenic acid (for example, derived from vegetable oil), eleostearic acid (for example, derived from vegetable oil), di-homo-γ-linolenic acid, arachidonic acid Examples thereof include fatty acids such as erucic acid and nervonic acid (for example, those derived from liver and animal fat).

  These fatty acids can be used alone or as a mixture of two or more. In the present invention, it is particularly preferable to use a natural product of these fatty acids or a natural product comprising a mixture of these fatty acids. For example, conjugated sunflower oil fatty acid rich in linoleic acid or oleic acid content or tall oil fatty acid rich in linoleic acid content can be used. These natural products are commercially available and are available at an advantageous price and with sufficient purity. The proportion of saturated fatty acids present in such natural products is preferably as low as possible, for example, less than 20% by weight, more preferably less than 10% by weight based on the total weight of monomer (b), more preferably 5% by weight. More preferably, it is less than.

The monomer (b) in the present invention is preferably a linear unsaturated monocarboxylic acid having a double bond in the molecule at or near the center, not the terminal or exo position of the molecule. Since the monomer (b) has such a structure, the molecular ends on both sides of the double bond become two side chains extending from the main chain of the copolymer, and the adsorptivity to the pigment is improved and more effective. In particular, bronzing is suppressed, and glossiness and scratch resistance are improved.
The unsaturated monocarboxylic acid used as the monomer (b) can be esterified or amidated in whole or in part as in the case of the monomer (a).

  By using an unsaturated monocarboxylic acid derivative as the monomer (b), it is possible to avoid the disadvantages caused by the olefinic monomer contained in a known customary dispersant. On the other hand, since polarity is added to a polymer by including a carboxy group, the aggregation suppression property of a pigment improves more. Furthermore, the carboxy group can preferably act as an adsorption promoter on the pigment surface.

  Monomers (b) can be used alone or in combination of two or more different monomers (b). The content of the monomer (b) in the water-soluble comb structure polymer can be, for example, 2 to 80 mol%, preferably 5 to 60 mol%, more preferably 10 to 40 mol%.

(C) Polyalkyleneoxyallyl ether In the present invention, the polyalkyleneoxyallyl ether (allyl polyether derivative, hereinafter sometimes referred to as “monomer (c)”) is a compound represented by the following general formula (1) Is preferred.

CH ₂ = CH—CH ₂ —O— [AO] _p —R ¹ ... (1)

Here, AO represents an alkyleneoxy unit having 2 to 10 carbon atoms, and R ¹ represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or CO—R ² . Here, R ² represents an alkyl group having 1 to 6 carbon atoms. p can be selected so that the number average molecular weight Mn of the allyl polyether derivative is 5,000 g / mol or less.

  In the present invention, when a carboxylic acid anhydride is used as the monomer (a), an undesired ring opening of the acid anhydride ring may occur during the polymerization, and therefore the monomer (c) does not have a hydroxyl group. Those are preferred.

  In the monomer (c), AO in the same molecule means the same or different alkyleneoxy unit having 2 to 10 carbon atoms. As AO, an ethyleneoxy (= EO) unit or a propyleneoxy (= PO) unit is preferable. The water solubility and / or polarity of the copolymer can be controlled by the chemical composition and molecular weight of the polyether moiety of the allyl polyether derivative. Thus, for example, increasing the EO moiety in an allyl polyether having EO and PO can increase the hydrophilicity of the copolymer, resulting in better water solubility.

  The monomer (c) in the present invention is also preferably an EO / PO allyl polyether derivative. The EO / PO allyl polyether derivative is represented by the following general formula (2).

_{CH 2 = CH-CH 2 -O-} [EO] m - [PO] n -R 1 ·· (2)

Here, R ¹ is the same as R ¹ in the general formula (1), and the sum of m and n corresponds to p in the general formula (1). That is, m and n can be selected so that the number average molecular weight Mn of the allyl polyether derivative is 5,000 g / mol or less.

By setting the number average molecular weight of the monomer (c) to 5,000 g / mol or less, the resulting copolymer can have sufficient solubility and wide compatibility without excessively high molecular weight. The number average molecular weight Mn is preferably 200 g / mol or more from the viewpoint of adsorptivity to the pigment.
The number average molecular weight of the monomer (c) is preferably 300 to 3,000 g / mol, and more preferably 400 to 2,000 g / mol.

  In the present invention, for example, the following allyl polyether derivatives can be preferably used. Polyoxyethylene allyl methyl ether, polyoxypropylene allyl methyl ether, polyoxypropylene monoallyl ether monoacetate, polyoxyethylene-polyoxypropylene allyl methyl ether. These can be obtained, for example, from Nippon Oil & Fats Co., Ltd. under the trademarks Uniox PKAR, Unisafe PKAR and Unicelin PKAR.

  When the allyl polyether derivative represented by the general formula (2) having different alkyleneoxy units is used, for example, different alkyleneoxy units (in this case, [EO] and [PO]) are present in the polyalkyleneoxy group. It may be dispersed randomly, or may exist as a gradient structure or a block structure.

  These allyl polyether derivatives can be produced using all known methods from allyl alcohol and in particular oxiranes such as ethylene oxide, propylene oxide and / or butylene oxide. The subscripts m and n described above can be controlled by appropriately selecting the molar ratio. Furthermore, using well-known methods and selecting the reaction conditions for oxirane, different block polyalkylene oxide units or randomly dispersed polyalkylene oxide units can be produced.

  Monomers (c) can be used alone or in combination of two or more different monomers (c). The content of the monomer (c) in the water-soluble comb-type structure polymer is, for example, 1 to 90 mol%, preferably 5 to 60 mol%, more preferably 10 to 40 mol%. By setting the content of the monomer (c) to 1 mol% or more, a sufficient adsorption layer can be provided on the surface of the pigment particles. Moreover, by setting it as 90 mol% or less, affinity to the pigment particle surface can be made sufficiently large. As a result, bronzing is more effectively suppressed, and glossiness and scratch resistance are improved.

  In the present invention, a monomer (c) having a relatively hydrophobic alkyleneoxy chain (for example, PO), a monomer (c) having a relatively hydrophilic alkyleneoxy chain (for example, EO), and the like It is preferable to use a mixture comprising two or more different monomers (c). Thereby, the suppression effect of bronze, the improvement effect of glossiness, and the improvement effect of abrasion resistance can be acquired more effectively.

(D) Other monomer The said water-soluble comb-type structure polymer in this invention can be comprised using (d) other monomers as needed in addition to the said monomers (a)-(c). The (d) other monomer means a monomer other than the monomer (a), the monomer (b), and the monomer (c) (hereinafter sometimes referred to as “monomer (d)”).

  Examples of the monomer (d) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and stearyl (meth). ) Acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, trifluoromethyl (meth) acrylate, hexafluoropropyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, propylene glycol mono (meth) ) Acrylic esters and / or methacrylic esters such as acrylates and polyethylene glycol mono (meth) acrylates; styrene, α-methylstyrene, vinyl Vinyl compounds such as ene and vinylcyclohexane; vinyl acetate, vinyl propionate, vinyl butanoate, vinyl hexanoate, vinyl octoate, vinyl decanoate, vinyl stearate, vinyl palmitate, vinyl propionate, divinyl adipate, sebacic acid Aliphatic or aromatic carboxylic acid vinyl esters such as divinyl, vinyl 2-ethylhexanoate and vinyl trifluoroacetate; allyl acetate, allyl propionate, allyl butanoate, allyl hexanoate, allyl octanoate, allyl decanoate Allyl stearate, allyl palmitate, allyl salicylate, allyl lactate, diallyl oxalate, allyl stearate, diallyl succinate, diallyl glutarate, diallyl adipate, diallyl pimelate, diallyl maleate, phthalate Mention may be made of aliphatic or aromatic allyl esters such as diallyl acid and diallyl isophthalate; alkyl vinyl ethers such as vinyl ethyl ether and / or vinyl polyether.

  In the present invention, the monomer (d) is not critical to the pigment aggregation inhibiting property, but can be used in combination to finely adjust various properties of the copolymer, particularly compatibility.

  Monomers (d) can be used alone or in combination of two or more monomers (d). The content of the monomer (d) in the water-soluble comb structure polymer is, for example, 0 to 30 mol%, preferably 0 to 15 mol%, more preferably 0 to 5 mol%, still more preferably 0 mol%. can do.

  The water-soluble comb structure polymer in the present invention can be produced by known and frequently used polymerization methods such as emulsion, suspension, precipitation, solution and bulk polymerization. Among these, it is preferable to manufacture using free radical solution polymerization and bulk polymerization.

  As the polymerization method, for example, a method in which all or a part of the monomer is added as initial filling and a reaction initiator is added during the polymerization can be applied. Polymerization can be carried out using a normal vessel or, if necessary, a pressure vessel. A stirrer, a supply tank, and a metering device can be attached to this container as needed.

  In the present invention, for example, it is preferable to include at least one of the monomers (b) and (c) in the initial filling, and slowly supply the monomer (a) to the initial filling. This method is particularly desirable when a dicarboxylic acid derivative having low solubility such as maleic anhydride is used as the monomer (a). In such cases, monomer (a) can be added with the initiator within a few hours, preferably less than 4 hours, more preferably within about 2 hours. After the reaction, a post-polymerization reaction time of up to several hours, preferably less than 4 hours, more preferably about 2 hours can be provided. Thereafter, the completion of the polymerization reaction can be confirmed using, for example, nuclear magnetic resonance spectroscopy. In some cases, the completion of the reaction can be further improved by adding the monomer (a) and, if necessary, an initiator within the reaction time after the polymerization.

Depending on the polymerization method used, the water-soluble comb-type structure polymer in the present invention can be produced in bulk or in the presence of a suitable solvent, mixed solvent or other suitable carrier medium, depending on the viscosity.
There is no restriction | limiting in particular as a solvent which can be used for this invention. For example, hydrocarbons such as toluene, xylene, aliphatic and / or alicyclic petroleum fractions; chlorinated hydrocarbons such as chloroform, trichloroethane; cyclic and acrylic acids such as dioxane, tetrahydrofuran, polyalkylene glycol dialkyl ethers Ethers; esters such as ethyl acetate, butyl acetate, butyl lactone, phthalates; or other plasticizers, dicarboxylic or polycarboxylic esters, dialkyl esters of dicarboxylic acids having 2 to 4 carbon atoms (hereinafter “dibasic” An alkyl glycol ester such as ethyl glycol acetate and methoxypropyl acetate; a ketone such as methyl isobutyl ketone, cyclohexanone and acetone; an aliphatic alcohol such as propylene glycol; Ethers such as 2-butoxy-ethanol, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, 2-phenoxyethanol or 2- (2-phenoxyethoxy) ethanol; polyethers; dimethylformamide, N- Examples include acid amides such as methylpyrrolidone.

  In the present invention, the polymerization reaction is preferably performed using a water-soluble solvent. The solvent used in the polymerization reaction may be left as it is in the reaction mixture, or may be completely or partially removed and replaced with another solvent or a carrier medium (for example, water) as necessary. Depending on the compatibility, the copolymers in the present invention are such as resins, resin solutions, reactive diluents, binders or other wetting and dispersing agents, anti-precipitation agents, surface active additives such as silicon. Can be combined.

In the present invention, after the polymerization reaction, the solvent can be completely or partially removed by distillation or the like by an appropriate method such as azeotropic distillation under reduced pressure and / or water. Alternatively, a poor solvent such as an aliphatic hydrocarbon, for example hexane, can be added to precipitate the copolymer and then filtered to separate the copolymer, which can be further dried as required. . The copolymer thus obtained can be diluted with an appropriately selected solvent. Further, if necessary, it can be used in an undiluted form as in the case of powder coating.
If necessary, after removing the solvent of the copolymer solution by distillation under reduced pressure and / or using an appropriate method such as adding water to azeotrope, an appropriately selected high boiling point solvent can be added. In this way, the copolymer can be transferred to a carrier medium suitable for use in the present invention.

  Furthermore, the water-soluble comb-type structure polymer in the present invention can produce a copolymer without using any solvent for the monomer for producing the copolymer. In this case, it is not necessary to remove the solvent used for the polymerization reaction, which is advantageous when the copolymer is used in a solvent-free or aqueous system.

  The water-soluble comb structure polymer in the present invention is preferably 60 to 220 ° C., more preferably 100 to 180 ° C. in the presence of a commonly used free radical forming initiator. Preferably, it can manufacture by performing a copolymerization at 120-160 degreeC.

The initiator that forms free radicals can be selected from peroxides, hydroperoxides, persulfates, azo compounds and redox catalysts. The redox catalyst is composed of an oxidizing component and a reducing component such as ascorbic acid, glucose, and bisulfite.
Preferred initiators include 2,2-azodi (isobutyronitrile), 2,2-azodi (2-methylbutyronitrile), t-butyl-permaleate, t-butylperoxyisopropyl carbonate, t -Butyl perbenzoate (TBPB), dicumyl peroxide, di-t-amyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, didodecanoyl peroxide, dibenzoyl peroxide, tert-butyl peracetate, Examples thereof include tert-butyl-2-methyl perpropinate, and 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane and di-t-butyl peroxide are particularly preferable. The amount of the reaction initiator used is, for example, 0.1 to 10% by mass, preferably 0.2 to 5% by mass based on the monomer used.

  As a number average molecular weight of the copolymer in this invention, it can be set as 1,000-50,000 g / mol, for example, Preferably it is 1,500-25,000 g / mol.

The molecular weight and molecular weight distribution of the copolymer can be controlled by the reaction conditions to be applied, in particular, the type and amount of the initiator, the ratio of monomers, and the polymerization temperature. In the present invention, a polymerization regulator that is usually used can be used as necessary.
Examples of the polymerization regulator include sulfur compounds such as short chain aldehyde, mercaptoacetic acid, mercaptopropionic acid, n-dodecyl mercaptan, t-dodecyl mercaptan, mercaptoethanol and thioglycolic acid ester. The usage-amount of these polymerization regulators is 0.1-5 mass% on the basis of the monomer to be used, for example.

  To carry out the polymerization reaction, the initially charged monomer can be heated to the reaction temperature, if desired, under an inert gas atmosphere such as nitrogen gas. The reaction initiator can be added separately or can be added simultaneously with the monomer (a). The same applies to the polymerization regulator.

  The copolymer obtained as described above can be directly used as the water-soluble comb-type structure polymer in the present invention. On the other hand, in order to further demonstrate the control of the wet performance and dispersion performance of the obtained copolymer, all or part of the carboxyl groups and acid anhydride groups of the copolymer are amidated, esterified, neutralized, Alternatively, it can be hydrolyzed.

  For this purpose, this is optionally carried out in the presence of customary catalysts such as p-toluenesulfonic acid, sulfonic acids such as alkylbenzene sulfonic acids or organometallic compounds such as dibutyltin dilaurate, tetraalkoxytitanium. The copolymer can be pressurized as desired and mixed with, for example, an appropriately selected alcohol, amine and / or aminoalcohol at 20 to 250 ° C, preferably 50 to 200 ° C.

  This reaction can be carried out in bulk or in a suitable inert solvent. This reaction rate is similar to that of a single carboxylic acid anhydride, and the reaction is generally completed in 1 to 6 hours. In the case of partial solvolysis, anhydride groups remain in the copolymer, which can be further hydrolyzed with water. If necessary, it can be neutralized with an alkali metal hydroxide, an alkaline earth metal hydroxide, an aqueous ammonia solution and / or an amino alcohol. Furthermore, it can be left unreacted in the copolymer.

  If necessary, the hydrolysis can be performed simultaneously with the neutralization treatment of the subsequent copolymer. This is equally applicable to polymers that have not reacted with alcohols, amines and / or aminoalcohols.

When the copolymer in the present invention is amidated, the amide can be formed using ammonia or a primary or secondary amine generally having 1 to 50 carbon atoms, preferably 2 to 30 carbon atoms.
Examples of the primary amine and the secondary amine include methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, hexylamine, cyclohexylamine, methylcyclohexylamine, 2-ethylhexylamine, n -Octylamine, isotridecylamine, tallow fatty amine, stearylamine, oleylamine, etc., as well as dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, diisobutylamine, dihexylamine, dicyclohexylamine N-methyl-cyclohexylamine, N, N-bis (methylcyclohexyl) amine, di-2-ethylhexylamine, di-n-octylamine, diisotridecylamine, di- Saturated and unsaturated aliphatic amines such as aliphatic aliphatic amines, distearylamine and dioleylamine and alicyclic amines; aniline, naphthylamine, o-, m- and p-toluidine and 2-phenylethylamine, and N-ethyl Aromatic amines such as o-toluidine; alkanolamines such as ethanolamine, n-propanolamine, aminomethylpropanol, diethanolamine and di-n-propanolamine; morpholine, 4,9-dioxadodecane-1, Ethers such as 12-diamine, 4,7,10-trioxatridecane-1,13-diamine, bis (3-aminopropyl) polytetrahydrofuran and amine-terminated polyoxyalkyleneamines (commercial product: Jeffamines from Huntsman) Amines and polyethers Min; ethylenediamine, 1,3-diaminopropane, hexamethylenediamine, dipropylenediamine and 3,3′-dimethyl-4,4′-diaminophenoxymethane, and diethyltriamine, dipropyltriamine, bishexamethylenetriamine and N- Examples thereof include diamines such as tallow aliphatic 1,3-diaminopropane and oligoamines.

  In the present invention, 2- (diethylamino) ethylamine, 3- (diethylamino) propylamine, N, N-diethyl-1,4-butane-diamine, 1-diethylamino-4-aminopentane, N- (3-amino- Propyl) morpholine, N- (2-aminoethyl) piperazine, 1-methylpiperazine and aminoethylpiperazine can be preferably used, more preferably 3- (dimethylamino) propylamine and / or N- (3-amino Examples thereof include aliphatic diamines having primary or secondary amino groups and tertiary amino groups such as propyl) imidazole. In the case of having a tertiary amino group, the tertiary amino group may be a heterocyclic partial structure.

In the present invention, the carboxyl group or acid anhydride group in the copolymer may be esterified with, for example, primary, secondary, and tertiary alcohols having 1 to 50 carbon atoms, preferably 4 to 30 carbon atoms. it can. These alcohols may be linear or branched and may be saturated or unsaturated.
Examples of the alcohol suitable for the present invention include the following alcohols.

  Methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, pentanol, hexanol, octanol, 2-ethylhexanol, nonaol, decanol, dodecanol, tridecanol and their isomers, cyclohexanol, tallow fatty alcohol, Aliphatic alcohols such as stearyl alcohol and oleyl alcohol, aliphatic and alicyclic alcohols such as oxo alcohols such as C9 / C11 oxo alcohol and C13 / C15 oxo alcohol; Ziegler alcohol having 12 to 24 carbon atoms; alkylphenol Aromatic alcohols such as bisphenol A and ethoxylated alkylphenols; ethylene glycol, 1,10-decanediol, 2-ethyl-2-hydroxy Diols such as methylpropane-1,3-diol, glycerol, pentaerythritol, sorbitol and glucose, oligools and polyols; ethylene glycol monoethyl ether, di and triethylene glycol monoethyl ether, 2-butoxyethanol, di and tri Ether alcohols and polyether diols such as ethylene glycol monobutyl ether, propylene glycol monomethyl ether, 2-phenoxyethanol or 2- (2-phenoxyethoxy) ethanol, polytetrahydrofuran, polyethylene glycol and polypropylene glycol.

  In the present invention, in order to neutralize the acid group in the copolymer, in addition to the alkali metal hydroxide, alkaline earth metal hydroxide and ammonia described above, primary, secondary or tertiary amine and amino acid are used. Alcohol can be used. Specifically, for example, calcium hydroxide, magnesium hydroxide, butylamine, dibutylamine, triethylamine, N-oleyl-1,3-propanediamine, dimethylaminoethanol, diethylaminoethanol, aminomethylpropanol, 2-dibutylaminoethanol, monoamine Diamines or polyamine alkoxylates, monoethanolamine, diethanolamine or triethanolamine, N, N-bis [poly (oxyethylene)]-N-oleylamine. Particularly preferred are those in the form of an alkali solution of 25 to 50% by weight of sodium hydroxide and / or potassium hydroxide or an amino alcohol.

The degree of neutralization can be guided by the hydrophilicity of the desired copolymer. For example, the neutralization amount in the hydrophilically adjusted copolymer can be less than the neutralization amount in the hydrophobically adjusted copolymer.
The degree of neutralization also depends on the type of neutralizing agent. For example, when triethyleneamine is used, it is necessary to increase the degree of neutralization compared to when potassium hydroxide is used. In general, the degree of neutralization of the acid groups remaining in the copolymer after complete hydrolysis of the acid anhydride groups can be, for example, 0-100%, and 50-100% Is preferred. In the present invention, a copolymer can be used without neutralizing the acid group.

  Neutralization is preferably performed at a temperature of 40 to 100 ° C., more preferably 50 to 70 ° C., by homogenization with water or addition of a neutralizing agent. In a pressurized reaction vessel, a high temperature is used, but in this case, it is necessary to consider the hydrolysis stability of the existing ester groups and amide groups. The anhydride group present in the copolymer is hydrolyzed into a carboxyl group in this process, and is subject to neutralization. In the present invention, the pH of the polymer dispersion in a ready-to-use state is, for example, 4 to 10, preferably 5 to 8, more preferably 7 ± 0.5.

Similar to the solvolysis or hydrolysis and / or neutralization of the carboxyl group or acid anhydride group in the copolymer, the copolymer can be obtained by appropriately selecting the reaction conditions using ammonia or a primary amine. It is also possible to make an imide structure from the dicarboxylic anhydride structure therein. These imide functional groups can be converted into aqueous dispersions or aqueous solutions in the same manner as esterified or amidated copolymers.

As the water-soluble comb-type structural polymer in the present invention, from the viewpoint of suppressing bronze, improving glossiness, and improving scratch resistance, maleic anhydride is used in an amount of 1 to 80 mol% as monomer (a), and monomer (b ) As tall oil fatty acid and conjugated sunflower oil fatty acid in an amount of 2-80 mol%, and monomer (c) as polyoxyethylene allyl methyl ether, polyoxypropylene monoallyl ether monoacetate, polyoxyethylene-polyoxypropylene-allyl It is preferably a copolymer obtained by using 1 to 90 mol% of methyl ether and 0 to 30 mol% of monomer (d), and using 40 to 65 mol% of maleic anhydride or the like as monomer (a). And 10-40 mol% of tall oil fatty acid, conjugated sunflower oil fatty acid, etc. as monomer (b) And a copolymer obtained using 10 to 40 mol% of polyoxyethylene allyl methyl ether, polyoxypropylene monoallyl ether monoacetate, polyoxyethylene-polyoxypropylene-allylmethyl ether, etc. as the monomer (c). Is more preferable.
Furthermore, the water-soluble comb structure polymer in the present invention is also preferably a reaction product of the above-mentioned suitable copolymer with diethanolamine, oleylamine ethoxylate, or the like.

  In the inkjet recording medium for pigment ink of the present invention, a coating liquid for forming an ink receiving layer containing a pigment and a binder is coated on a support to form a first coating layer, and the first coating layer is formed on the first coating layer. It can manufacture by apply | coating the coating liquid containing the said water-soluble comb-type structure polymer so that the 2nd application layer containing the said water-soluble comb-type structure polymer may be formed.

  In the production of the ink-jet recording medium for pigment ink, the first coating layer and the second coating layer may be formed simultaneously, and then the first and second coating layers may be dried. After the coating layer is formed and dried, the second coating layer may be formed and dried. In the present invention, it is preferable that the first coating layer is formed and dried, and then the second coating layer is formed and dried.

  For example, an extrusion die coater, an air doctor coater, a bread coater, a rod coater, a knife coater, a squeeze coater, and a reverse roll can be applied to the ink receiving layer forming coating solution and the coating solution containing the water-soluble comb structure polymer. It can be performed by a known coating method using a coater, bar coater or the like.

  In the present invention, the coating solution containing the water-soluble comb-type structural polymer has a solid content coating amount of the water-soluble comb-type structural polymer of 5% by mass to the coating amount of the ink-receiving layer-forming coating solution. It is preferable to apply so that it may become 50 mass%, It is more preferable to apply so that it may become 10 mass%-45 mass%, It is especially preferable to apply so that it may become 15 mass%-40 mass%. By setting the coating amount to 5% by mass or more, bronzing can be more effectively suppressed, and glossiness and scratch resistance can be improved more effectively. Moreover, the fall of the density | concentration at the time of printing can be suppressed by setting it as 50 mass% or less.

[Support]
As the support, 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 CD-ROM or DVD-ROM, a write-once optical disk such as CD-R or DVD-R, or a rewritable optical disk may be used as a support, and an ink receiving layer may be provided on the label surface side. it can.

The material that can be used for the transparent support is preferably a material that is transparent and can withstand radiant heat when used in an OHP or a backlight display. Examples of such materials include polyesters such as polyethylene terephthalate (PET); polysulfone, polyphenylene oxide, polyimide, polycarbonate, polyamide, and the like. Of these, polyesters are preferable, and polyethylene terephthalate is particularly preferable.
Although there is no restriction | limiting in particular as thickness of the said transparent support body, 50-200 micrometers is preferable at the point of the ease of handling.

  As the highly glossy opaque support, one having a glossiness of 40% or more on the surface on which the ink receiving layer is provided is preferable. The glossiness is a value determined according to the method described in JIS P-8142 (75-degree specular gloss test method for paper and paperboard). Specifically, the following supports are mentioned.

For example, high gloss paper support such as art paper, coated paper, cast coated paper, baryta paper used for silver salt photographic support, etc .; polyesters such as polyethylene terephthalate (PET), nitrocellulose, cellulose acetate , Cellulose esters such as cellulose acetate butyrate, and plastic films such as polysulfone, polyphenylene oxide, polyimide, polycarbonate, and polyamide are made opaque by adding a white pigment or the like (surface calendering may be applied). Glossy film; or a support in which a polyolefin coating layer containing or not containing a white pigment is provided on the surface of a highly glossy film containing the various paper supports, the transparent support or the white pigment. Etc.
A white pigment-containing foamed polyester film (for example, foamed PET containing polyolefin fine particles and forming voids by stretching) can also be suitably exemplified. Furthermore, resin-coated paper used for silver salt photographic printing paper is also suitable.

Although there is no restriction | limiting in particular also about the thickness of the said opaque support body, 50-300 micrometers is preferable at the point of the ease of handling.
In addition, it is preferable to use a surface of the support that has been subjected to corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet irradiation treatment or the like in order to improve wettability and adhesion.

Next, a base paper used for a paper support such as resin-coated paper will be described.
The base paper is made from wood pulp as a main raw material and, if necessary, paper using synthetic pulp such as polypropylene or synthetic fibers such as nylon or polyester in addition to wood pulp. As the wood pulp, any of LBKP, LBSP, NBKP, NBSP, LDP, NDP, LUKP, NUKP can be used, but it is preferable to use more LBKP, NBSP, LBSP, NDP, LDP with a lot of short fibers. preferable. However, the ratio of LBSP and / or LDP is preferably 10% by mass to 70% by mass.

As the above-mentioned pulp, chemical pulp (sulfate pulp or sulfite pulp) with few impurities is suitably used, and a pulp whose whiteness is improved by performing a bleaching treatment 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. The 4 mesh residue is preferably 20% by mass or less.

The basis weight of the base paper is preferably 30 to 250 g / ^{m 2,} especially 50 to 200 g / ^{m 2} is preferred. 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 polyethylene covering the front and back surfaces of the base paper is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but some other LLDPE, polypropylene, etc. can also be used.

  In particular, the polyethylene layer on the side that forms the ink-receiving layer is added with rutile or anatase-type titanium oxide, fluorescent whitening agent, ultramarine, and polyethylene, as is widely done for 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.

  Polyethylene-coated paper can be used as glossy paper, or matte or silky surface that can be obtained with ordinary photographic printing paper by applying a so-called molding process when polyethylene is melt-extruded and coated on the base paper surface. 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 contained in the backcoat layer include light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, and aluminum silicate. , Diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, colloidal alumina, pseudoboehmite, aluminum hydroxide, alumina, lithopone, zeolite, hydrous halloysite, magnesium carbonate, magnesium hydroxide, white inorganic pigment, styrene And organic pigments such as polyethylene plastic pigments, acrylic plastic pigments, polyethylene, microcapsules, urea resins, and melamine resins.

Examples of the aqueous binder used in the backcoat 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 an antifoaming agent, an antifoaming agent, a dye, a fluorescent brightening agent, a preservative, and a water-proofing agent.

[Ink receiving layer]
The ink receiving layer in the present invention contains at least one kind of pigment and at least one kind of binder. Preferably, the pigment, the binder, a crosslinking agent capable of crosslinking the binder, and a mordant and other components as necessary. (Surfactant etc.) can be used. Moreover, you may comprise previously further including the water-soluble comb type | mold structure polymer as stated above.

  The ink receiving layer contains a pigment (hereinafter sometimes referred to as “fine particles”) to have a porous structure, thereby improving the ink absorption performance. In particular, when the solid content of the fine particle ink receiving layer is 50% by mass or more, and more preferably more than 60% by mass, it is possible to obtain a more favorable porous structure, thereby further improving the ink absorbability. be able to. Here, the solid content of the fine particle ink receiving layer is a content calculated based on components other than water in the composition constituting the ink receiving layer.

  The porous ink-receiving layer is a layer having a porosity of 50 to 75%, preferably 60 to 70%. If the porosity is 50% or less, ink absorbability may be insufficient, and if it is 75% or more, a problem of powder falling due to insufficient binder may occur. Further, in view of the quality of the ink jet recording medium, the layer thickness of the ink receiving layer is preferably 10 to 40 μm.

-Pigment-
As the pigment (fine particles), either organic fine particles or inorganic fine particles can be used. Preferred examples of the organic fine particles include polymer fine particles obtained by, for example, emulsion polymerization, microemulsion polymerization, soap-free polymerization, seed polymerization, dispersion polymerization, suspension polymerization, and the like. Specifically, polyethylene, polypropylene, Examples include polystyrene, polyacrylate, polyamide, silicon resin, phenol resin, natural polymer powder, latex or emulsion polymer fine particles, and the like.

  Examples of the inorganic fine particles include silica fine particles, colloidal silica, titanium dioxide, barium sulfate, calcium silicate, zeolite, kaolinite, halloysite, mica, talc, calcium carbonate, magnesium carbonate, calcium sulfate, pseudoboehmite, zinc oxide, Examples thereof include zinc hydroxide, alumina, aluminum silicate, calcium silicate, magnesium silicate, zirconium oxide, zirconium hydroxide, cerium oxide, lanthanum oxide, and yttrium oxide.

  Among these, inorganic fine particles are preferable from the viewpoint of ink absorbability and image stability, and silica fine particles, colloidal silica, alumina fine particles, or pseudoboehmite are preferable from the viewpoint of forming a better porous structure. The fine particles may be used as primary particles or in a state where secondary particles are formed. The average primary particle size of these fine particles is preferably 2 μm or less, and more preferably 200 nm or less.

  Among these, silica fine particles are generally roughly classified into wet method particles and dry method (vapor phase method) particles according to the production method. In the wet method, a method is mainly used in which active silica is produced by acid decomposition of silicate, and this is appropriately polymerized and coagulated and precipitated to obtain hydrous silica. On the other hand, the gas phase method is a method by high-temperature gas phase hydrolysis of silicon halide (flame hydrolysis method), a method in which silica sand and coke are heated and reduced by an arc in an electric furnace and oxidized with air. The method of obtaining anhydrous silica by the (arc method) is the mainstream, and the “gas phase method silica” means anhydrous silica fine particles obtained by the gas phase method. As the silica fine particles in the present invention, gas phase method silica fine particles are particularly preferable.

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.

  Since the vapor phase silica has a particularly large specific surface area, the ink absorption and retention efficiency is high, and since the refractive index is low, transparency can be imparted to the receiving layer by dispersing it to an appropriate particle size. It is characterized by high color density and good color development. The transparency of the receiving layer is important not only for applications that require transparency, such as OHP, but also for obtaining high color density and good color development gloss even when applied to recording media such as photo glossy paper. It is.

  The average primary particle size of the vapor phase silica is preferably 30 nm or less, more preferably 20 nm or less, particularly preferably 10 nm or less, and most preferably 3 to 10 nm. Vapor phase silica is easy to adhere to each other by hydrogen bonds with silanol groups, so that when the average primary particle size is 30 nm or less, a structure with a large porosity can be suitably formed, and ink absorption characteristics are effective. Can be improved.

  Silica fine particles may be used in combination with the other fine particles described above. When the other fine particles and the vapor phase silica are used in combination, the content of the vapor phase silica in all the fine particles is preferably 30% by mass or more, and more preferably 50% by mass or more.

As the inorganic fine particles, alumina fine particles, alumina hydrate, a mixture or a composite thereof are also preferable. Of these, alumina hydrate is preferable because it absorbs and fixes ink well, and pseudoboehmite (Al ₂ O ₃ .nH ₂ O) is particularly preferable. Alumina hydrates can be used in various forms, but it is preferable to use sol boehmite as a raw material because a smooth layer can be easily obtained.

  About the pore structure of pseudo boehmite, the average pore radius is preferably 1 to 25 nm, and more preferably 2 to 10 nm. The pore volume is preferably 0.3 to 2.0 ml / g, more preferably 0.5 to 1.5 ml / g. Here, the pore radius and the pore volume are measured by a nitrogen adsorption / desorption method, and can be measured using, for example, a gas adsorption / desorption analyzer (for example, trade name “Omni Soap 369” manufactured by Coulter).

  Among the alumina fine particles, vapor-phase method alumina fine particles are preferable because of their large specific surface area. The average primary particle diameter of the vapor phase alumina fine particles is preferably 50 nm or less, and more preferably 20 nm or less. Furthermore, colloidal silica having an average primary particle size of 50 nm or less is also preferable.

  The above-mentioned fine particles are, for example, JP-A-10-81064, JP-A-10-119423, JP-A-10-157277, JP-A-10-217601, JP-A-11-348409, JP-A-2001-138621, JP-A-2000-43401. 2000-212235, 2000-309157, 2001-96897, 2001-138627, JP-A-11-91242, 8-2087, 8-2090, 8-2091, The embodiments disclosed in JP-A-8-2093, JP-A-8-174992, JP-A-11-192777, JP-A-2001-301314 and the like can also be preferably used.

-Binder-
Examples of the binder (hereinafter sometimes referred to as “water-soluble resin”) include, for example, polyvinyl alcohol resins (polyvinyl alcohol (PVA), acetoacetyl-modified polyvinyl alcohol, cations, which are resins having a hydroxy group as a hydrophilic structural unit). Modified polyvinyl alcohol, anion modified polyvinyl alcohol, silanol modified polyvinyl alcohol, polyvinyl acetal, etc.], cellulose resin [methyl cellulose (MC), ethyl cellulose (EC), hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), hydroxypropyl cellulose (HPC) ), Hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, etc.], chitins, chitosans, starch, trees with ether bonds [Polyethylene oxide (PEO), polypropylene oxide (PPO), polyethylene glycol (PEG), polyvinyl ether (PVE), etc.], resins having a carbamoyl group [polyacrylamide (PAAM), polyvinyl pyrrolidone (PVP), polyacrylic hydrazide, etc. ] Etc. are mentioned. Among these, polyvinyl alcohol resins, cellulose resins, resins having an ether bond, resins having a carbamoyl group, resins having a carboxyl group, and gelatins are preferable.
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, polyvinyl alcohol resin is 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, and 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.

  These water-soluble resins may be used alone or in combination of two or more. As content of the said water-soluble resin, 9-40 mass% is preferable with respect to the total solid content mass of an ink receiving layer, and 12-33 mass% is more preferable.

The water-soluble resin and the fine particles mainly constituting the ink receiving layer of the ink jet recording medium may be a single material or a mixed system of a plurality of materials.
From the viewpoint of maintaining transparency, the type of water-soluble resin combined with the fine particles, particularly silica fine particles, is important. When the gas phase method silica is used, the water-soluble resin is preferably a polyvinyl alcohol resin, more preferably a polyvinyl alcohol resin having a saponification degree of 70 to 100%, and a saponification degree of 80 to 99.5. % Of polyvinyl alcohol resin is particularly preferable.

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 silica fine particle form a hydrogen bond, a three-dimensional network having a secondary particle of the silica fine particle as a network chain unit. It becomes easy to form a structure. By forming this three-dimensional network structure, it is considered that a porous ink receiving layer having a high porosity and sufficient strength is formed.
In ink jet recording, the porous ink receiving layer obtained as described above can absorb ink rapidly by a capillary phenomenon, and can form dots with good roundness without ink bleeding.

  In addition, the polyvinyl alcohol resin may be used in combination with the other water-soluble resin. When the other water-soluble resin and the polyvinyl alcohol resin are used in combination, the content of the polyvinyl alcohol resin in the total water-soluble resin is preferably 50% by mass or more, and more preferably 70% by mass or more.

<Content ratio of fine particles to water-soluble resin>
The mass ratio [PB ratio; = x / y] of the mass (x) of the fine particles and the mass (y) of the water-soluble resin greatly affects the film structure and film strength of the ink receiving layer. That is, as the mass ratio (PB ratio) increases, the porosity, pore volume, and surface area (per unit mass) increase, but the density and strength tend to decrease.
As the PB ratio (x / y) in the ink receiving layer, the decrease in film strength and cracking during drying caused by the PB ratio being too large are prevented, 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 ink jet recording medium when passing through the transport system of the ink jet printer, the ink receiving layer needs to have sufficient film strength and is cut into a sheet shape. In addition, the ink receiving layer needs to have sufficient film strength from the viewpoint of preventing the ink receiving layer from cracking or peeling. In consideration of these, the PB ratio is more preferably 5 or less, and more preferably 2 or more from the viewpoint of ensuring high-speed ink absorbability in an inkjet printer.

For example, a coating solution in which gas phase method silica fine particles 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 and dried. In this case, a three-dimensional network structure in which the secondary particles of silica fine particles are network chains is formed, the average pore diameter is 25 nm or less, the porosity is 50 to 80%, the pore specific volume is 0.5 ml / g or more, 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 is a porous layer in which a coating layer containing fine particles and a water-soluble resin further contains a crosslinking agent capable of crosslinking the water-soluble resin, and is cured by a crosslinking reaction between the crosslinking agent and the water-soluble resin. Some embodiments are preferred.

Boron compounds are preferred for crosslinking the water-soluble resin, particularly polyvinyl alcohol resin. Examples of the boron compound include borax, boric acid, borate (for example, orthoborate, InBO ₃ , ScBO ₃ , YBO ₃ , LaBO ₃ , Mg ₃ (BO ₃ ) ₂ , Co ₃ (BO ₃ ) ₂ , two Borate (eg, Mg ₂ B ₂ O ₅ , Co ₂ B ₂ O ₅ ), metaborate (eg, LiBO ₂ , Ca (BO ₂ ) ₂ , NaBO ₂ , KBO ₂ ), tetraborate (eg, Na _{2 B 4 O 7 · 10H 2} O), can be mentioned five borate _{(e.g., KB 5 O 8 · 4H 2} O, Ca 2 B 6 O 11 · 7H 2 O, CsB 5 O 5) or the like. Among them, Of these, borax, boric acid, and borate are preferable, and boric acid is particularly preferable in that a crosslinking reaction can be promptly caused.

As the crosslinking agent for the water-soluble resin, the following compounds other than the boron compound may 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 2,983611; 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-based compounds such as dioxane; titanium-containing aluminum sulfate, chromium alum, potassium alum, metal-containing compounds such as zirconyl acetate, chromium acetate, polyamine compounds such as tetraethylenepentamine, hydrazide compounds such as adipic acid dihydrazide, A low molecule or polymer containing two or more oxazoline groups.
The crosslinking agents may be used alone or in combination of two or more.

  In the cross-linking curing, a coating liquid for forming an ink receiving layer containing fine particles, a water-soluble resin and the like (hereinafter also referred to as “ink receiving layer forming coating liquid” or “first liquid”) and / or the following. A cross-linking agent is added to the basic solution and (1) the first liquid is applied to form a coating layer, or (2) the coating layer formed by applying the first liquid is being dried. In any case before the coating layer exhibits reduced-rate drying, a basic solution having a pH of 7.1 or higher (hereinafter also referred to as “second liquid”) is applied to the coating layer. It is preferable.

The application of the cross-linking agent is preferably performed as follows when a boron compound is taken as an example. That is, when the ink receiving layer is a layer obtained by crosslinking and curing a coating layer coated with a coating solution (first solution) containing a water-soluble resin containing fine particles and polyvinyl alcohol, crosslinking curing is performed by (1) At the same time that one liquid is applied to form a coating layer, (2) any one of the coating layers formed by applying the first liquid and being dried and before the coating layer exhibits reduced-rate drying Sometimes, it is carried out by applying a basic solution (second liquid) having a pH of 7.1 or higher to the coating layer. The boron compound as the crosslinking agent may be contained in either the first liquid or the second liquid, and may be contained in both the first liquid and the second liquid.
1-50 mass% is preferable with respect to water-soluble resin, and, as for the usage-amount of a crosslinking agent, 5-40 mass% is more preferable.

-Mordant-
In the present invention, a mordant is preferably contained in the ink receiving layer in order to further improve the water resistance and aging resistance of the formed image. As the mordant, any of an organic mordant such as a cationic polymer (cationic mordant) and an inorganic mordant such as a water-soluble metal compound can be used. Of these, organic mordants are preferable, and cationic mordants are particularly preferable.

  The presence of the mordant in at least the upper layer of the ink receiving layer allows interaction with the liquid ink having an anionic dye as a coloring material, thereby stabilizing the coloring material and preventing water resistance and aging resistance. Further improvements can be made.

  In this case, it may be contained in either the ink receiving layer coating liquid (first liquid) or the basic solution (second liquid) when forming the ink receiving layer, but inorganic fine particles (especially gas phase method silica). It is preferable to contain and use in the 2nd liquid used as a liquid different from the liquid containing. That is, when the mordant is added directly to the ink receiving layer coating solution, aggregation may occur in the presence of an anion charge-containing silica vapor, but the mordant containing solution and the ink receiving layer coating solution are respectively If the method of independently preparing and coating each is employed, it is not necessary to consider the aggregation of inorganic fine particles, and the range of mordant selection is expanded.

As the cationic mordant, a polymer mordant having a primary to tertiary amino group or a quaternary ammonium base as a cationic functional group is preferably used, but a cationic non-polymer mordant is also used. be able to.
Examples of the polymer mordant include a homopolymer of a monomer having a primary to tertiary amino group and a salt thereof, or a quaternary ammonium base (hereinafter referred to as “mordant monomer”), the mordant monomer, Those obtained as copolymers or condensation polymers with other monomers (hereinafter referred to as “non-mordant polymer”) are preferred. These polymer mordants can be used in any form of a water-soluble polymer or water-dispersible latex particles.

  Examples of the mordant 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-N Benzyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N- (4-methyl) benzyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N-phenyl-Np-vinyl Benzylammonium 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.
Other examples of the copolymerizable monomer 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, etc.). In addition, since these allylamines and diallylamine derivatives are inferior in polymerizability in the amine form, 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-mordant monomer does not contain a basic or cationic moiety such as a primary to tertiary amino group and 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-mordant 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 cyanide such as (meth) acrylonitrile; olefins such as ethylene and propylene; and the like.

  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-mordant monomer can also be used alone or in combination of two or more.

Further, as a cationic mordant, 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 addition polymer, dimethyldiallylammonium phosphorus chloride -SO ₂ copolymers, diallylamine salt -SO ₂ copolymer, a Can be exemplified grade ammonium base-substituted alkyl group having an ester moiety (meth) acrylate-containing polymers, as preferred styryl polymers having a quaternary ammonium base-substituted alkyl group.

  Specific examples of the cationic mordant include JP-A Nos. 48-28325, 54-74430, 54-124726, 55-22766, 55-142339, 60-23850, and the like. 60-23851, 60-23852, 60-23853, 60-57836, 60-60643, 60-118834, 60-122940, 60-122941, 60- Nos. 122942, 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, 4,227,8353 Nos. 4282305 and 4450224, JP No. 161236, 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- 211235, 2000-309157, 2001-96897, 2001-138627, JP-A-11-91242, 8-2087, 8-2090, 8-2091, 8-2093 No. 8, No. 8-174992, No. 11-192777, JP-A No. 2001-301314, JP-B Nos. 5-35162, No. 5-35163, No. 5-35164, No. 5-88846, No. 7-88846 118333, JP-A 2000-344990, etc., Patents 2648847, 2666177, etc. Such as those described in the specifications and the like. Among these, polyallylamine and derivatives thereof are preferable, and diallyldialkyl cationic polymers are preferable in terms of structure.

  As the polyallylamine or a derivative thereof, various known allylamine polymers and derivatives thereof can be used. Examples of such derivatives include salts of polyallylamine and acids (acids include inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid, methanesulfonic acid, toluenesulfonic acid, acetic acid, propionic acid, cinnamic acid, (meth) An organic acid such as acrylic acid, or a combination thereof, or a salt of only a part of allylamine), a derivative of polyallylamine by a polymer reaction, a copolymer of polyallylamine and another copolymerizable monomer Specific examples of the monomer include (meth) acrylic acid esters, styrenes, (meth) acrylamides, acrylonitrile, vinyl esters and the like.

  Specific examples of polyallylamine and derivatives thereof include JP-B-62-31722, JP-B-2-14364, JP-B-63-43402, JP-A-63-43403, JP-A-63-45721, JP-A-63-29881, Japanese Patent Publication Nos. 1-26362, No. 2-56365, No. 2-57084, No. 4-41686, No. 6-2780, No. 6-45649, No. 6-15592, No. 4-68622, Patents No. 3199227, No. 3008369, JP-A-10-330427, JP-A-11-21321, JP-A-2000-281728, JP-A-2001-10636, JP-A-62-2256801, JP-A-7-173286, 7-213897, 9-235318, 9-302026, 11-21321, WO99 / 21901, WO99 / 193 No. 2, JP-A-5-140213, compounds described in JP Kohyo No. 11-506488, and the like.

Among the above-mentioned cationic mordants, diallyl dialkyl cationic polymers are preferable, and diallyl dimethyl cationic polymers are particularly preferable. The cationic mordant is preferably a cationic polymer having a weight average molecular weight of 60000 or less, particularly 40000 or less, from the viewpoint of dispersibility, particularly prevention of thickening.
The cationic mordant is also useful as the fine particle dispersant described above.

  Further, when added to the ink receiving layer coating solution, the sulfate ion concentration in the coating solution is preferably 1.5% by mass or less from the viewpoint of preventing thickening of the solution. This sulfate ion is contained in the polymerization initiator at the time of production of the cationic polymer, and since it remains in the polymer, the cationic mordant is formed using a polymerization initiator that does not emit sulfate ion. Is desirable.

  Examples of the inorganic mordant include polyvalent water-soluble metal salts and hydrophobic metal salt compounds. Specifically, 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, europium, gadolinium, dysprosium, erbium, ytterbium, hafnium, tungsten, bismuth metal salts or complexes.

  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, and second chloride. Copper, ammonium chloride (II) chloride dihydrate, copper sulfate, cobalt chloride, cobalt thiocyanate, cobalt sulfate, nickel sulfate hexahydrate, nickel chloride hexahydrate, nickel acetate tetrahydrate, nickel ammonium sulfate Hexahydrate, nickel amidosulfate tetrahydrate, aluminum sulfate, aluminum alum, basic polyaluminum hydroxide, aluminum sulfite, aluminum thiosulfate, polyaluminum chloride, aluminum nitrate nonahydrate, aluminum chloride hexahydrate , Ferrous bromide, ferrous chloride, ferric chloride, sulfuric acid Ferrous sulfate, ferric sulfate, zinc phenolsulfonate, zinc bromide, zinc chloride, zinc nitrate hexahydrate, zinc sulfate, titanium tetrachloride, tetraisopropyl titanate, titanium acetylacetonate, titanium lactate, zirconium acetylacetonate , Zirconyl acetate, zirconyl sulfate, zirconium ammonium carbonate, zirconyl stearate, zirconyl octylate, zirconyl nitrate, zirconium oxychloride, zirconium hydroxychloride, chromium acetate, chromium sulfate, magnesium sulfate, magnesium chloride hexahydrate, magnesium citrate Hydrate, sodium phosphotungstate, sodium tungsten citrate, 12 tungstophosphoric acid n hydrate, 12 tungstosilicic acid 26 hydrate, molybdenum chloride, 12 molybdophosphoric acid n hydrate, gallium nitrate, Germanium nitrate, strontium nitrate, yttrium acetate, yttrium chloride, yttrium nitrate, indium nitrate, lanthanum nitrate, lanthanum chloride, lanthanum acetate, lanthanum benzoate, cerium chloride, cerium sulfate, cerium octylate, praseodymium nitrate, neodymium nitrate, samarium nitrate, Examples include europium nitrate, gadolinium nitrate, dysprosium nitrate, erbium nitrate, ytterbium nitrate, hafnium chloride, and bismuth nitrate.

Among inorganic mordants, an aluminum-containing compound, a titanium-containing compound, a zirconium-containing compound, and a metal compound (salt or complex) of Group IIIB of the Periodic Table of Elements are preferable.
The addition amount in the ink receiving layer of the mordant is preferably ^{0.01~5g / m 2, 0.1~3g / m} 2 is more preferable.

-Other ingredients-
In addition to the above components, the ink-receiving layer or the coating solution for forming the ink-receiving layer (ink-receiving layer coating solution) may further include various known additives such as ultraviolet absorbers and antioxidants as necessary. Agent, optical brightener, monomer, polymerization initiator, polymerization inhibitor, anti-bleeding agent, preservative, viscosity stabilizer, antifoaming agent, surfactant, antistatic agent, matting agent, anti-curl agent, water resistance agent Etc. can be contained.

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 .

  Further, for the purpose of improving the dispersibility of the inorganic fine particles, the inorganic surface may be treated with a silane coupling agent. The silane coupling agent includes 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 a coupling treatment site. Those having the following are preferred.

  In the present invention, an embodiment in which the ink receiving layer coating solution contains a surfactant is preferred. Surfactants here include any of cationic, anionic, nonionic, amphoteric, fluorine, and silicon surfactants.

  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 may be contained in the ink receiving layer 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 total amount of the surfactant in the ink-receiving layer coating solution is preferably 0.001 to 2.0%, more preferably 0.01 to 1.0%.

  The ink-receiving layer is formed by applying a coating solution containing fine particles and a water-soluble resin to the support surface to form a coating layer, and further adding a crosslinking agent to the coating solution and / or the following basic solution, and ( 1) at the same time when the coating solution is applied to form a coating layer, or (2) during the drying of the coating layer formed by coating the coating solution and before the coating layer exhibits reduced-rate drying, In any case, it is preferably formed by a method (Wet-on-Wet method) in which a basic solution having a pH of 7.1 or higher is applied to the coating layer and the coating layer is crosslinked and cured. Here, the crosslinking agent capable of crosslinking the water-soluble resin is preferably contained in at least one or both of the coating solution and the basic solution. Providing the ink-receiving layer crosslinked and cured in this manner is preferable from the viewpoint of ink absorbability and prevention of film cracking.

  The mordant is desirably present so that the thickness of the mordant-existing portion from the surface of the receptor layer is 10 to 60% of the receptor layer thickness. For example, (1) a method of forming a coating layer containing the fine particles, a water-soluble resin, and a crosslinking agent, and applying a mordant-containing solution thereon, (2) a coating solution containing the fine particles, a water-soluble resin, and a mordant-containing solution. It can be formed by any method such as a method of applying multiple layers. The mordant-containing solution may contain inorganic fine particles, a water-soluble resin, a crosslinking agent, and the like.

  As described above, since a large amount of mordant is present in a predetermined part of the ink receiving layer, the ink-jet coloring material is sufficiently mordanted, color density, aging blur, gloss of printed part, and water resistance of characters and images after printing. This is preferable because ozone resistance is improved. Part of the mordant may be contained in the layer initially provided on the support, and in that case, the mordant to be applied later may be the same or different.

In the present invention, the ink-receiving layer coating liquid (first liquid) containing fine particles (for example, vapor phase silica) and a water-soluble resin (for example, polyvinyl alcohol) can be prepared, for example, as follows. . That is,
Fine particles such as vapor phase method silica are added to water together with a dispersant or the like (for example, silica fine particles in water are 10 to 20% by mass), pre-dispersed (primary dispersion) with a homomixer or the like, and then obtained dispersion The liquid is further dispersed (secondary dispersion) in, for example, one pass using a disperser such as an optimizer (manufactured by Sugino Machine Co., Ltd.), and then an aqueous polyvinyl alcohol (PVA) solution (for example, 1/3 of the above-mentioned gas phase method silica). Can be prepared by adding PVA of a moderate mass). In order to impart stability to the coating solution, it is preferable to adjust the pH to about 9.2 with aqueous ammonia or the like, or to use a dispersant. The obtained coating liquid is in a uniform sol state, and a porous ink-receiving layer having a three-dimensional network structure can be formed by coating this on a support by the following coating method and drying it.

  As the disperser used for dispersion, various conventionally known dispersers such as a colloid mill disperser, a high-speed rotating disperser, a medium stirring disperser (ball mill, sand mill, etc.), an ultrasonic disperser, and a high-pressure disperser are used. be able to. Among these, an ultrasonic disperser or a high-pressure disperser (particularly a high-pressure jet disperser) is preferable from the viewpoint of effectively dispersing the formed fine particles.

  Moreover, water, an organic solvent, or these mixed solvents can be used as a solvent in each process. Examples of the organic solvent that can be used for this coating include alcohols such as methanol, ethanol, n-propanol, i-propanol, and methoxypropanol, ketones such as acetone and methyl ethyl ketone, tetrahydrofuran, acetonitrile, ethyl acetate, and toluene. It is done.

Furthermore, a chaotic polymer can be used as the dispersant. Examples of the chaotic polymer include the aforementioned mordants. It is also preferable to use a silane coupling agent as the dispersant.
The amount of the dispersant added to the fine particles is preferably 0.1 to 30% by mass, and more preferably 1 to 10% by mass.

  The ink receiving layer coating solution is applied by a known coating method using, for example, 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, or the like. Can do.

  A basic solution (second liquid) is applied to the coating layer at the same time as or after the coating of the ink receiving layer coating liquid (first liquid), and the second liquid is applied to the coating layer after coating. You may give before it comes to show decremental drying. That is, after the application liquid for the ink receiving layer (first liquid) is applied, the second liquid is introduced while the applied layer exhibits constant rate drying. This second liquid may contain a mordant.

  Here, “before the coating layer comes to show reduced drying” usually refers to a process for several minutes immediately after the coating of the coating liquid for the ink-receiving layer. This shows a phenomenon of “constant rate drying” in which the content of the solvent (dispersion medium) of the ink decreases in proportion to time. 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.

  As described above, after the application of the first liquid, the coating layer is dried until the coating layer exhibits a reduced rate of drying. This drying is generally performed at 40 to 180 ° C. for 0.5 to 10 minutes (preferably, 0 .5-5 minutes). The drying time naturally varies depending on the coating amount, but usually the above range is appropriate.

  As a method of applying before the coating layer composed of the first liquid shows a reduced rate of drying, (1) a method of further coating the second liquid on the coating layer, (2) by a method such as spraying Examples of the spraying method include (3) a method in which the support on which the coating layer is formed is immersed in the second liquid.

  In the method (1), the application method for applying the second liquid is, for example, curtain flow coater, extrusion die coater, air doctor coater, bread coater, rod coater, knife coater, squeeze coater, reverse roll coater, bar A known coating method such as a coater can be used. Among them, 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 application | coating of a 2nd liquid, generally it heats at 40-180 degreeC for 0.5 to 30 minutes, and drying and hardening are performed. Especially, it is preferable to heat at 40-150 degreeC for 1 to 20 minutes.

  Further, when the basic solution (second liquid) is applied simultaneously with the application of the ink-receiving layer coating liquid (first liquid), the first liquid and the second liquid are brought into contact with the support. Thus, the ink receiving layer can be formed by simultaneously coating (multilayer coating) on the support, followed by drying and curing.

  The simultaneous coating (multilayer coating) can be performed by a coating method using, for example, an extrusion die coater or a curtain flow coater. After the simultaneous coating, the formed coating layer is dried. In this case, the drying is generally performed by heating the coating layer at 40 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 coating (multilayer coating) is performed by, for example, an extrusion die coater, the two types of coating liquid discharged at the same time are close to the discharge port of the extrusion die coater, that is, before moving onto the support. A multilayer is formed, and in that state, the multilayer is applied on the support. Since the two-layer coating liquid that has been layered before coating is likely to cause a crosslinking reaction at the interface between the two liquids when transferred to the support, the two liquids to be discharged 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 mentioned above, it is preferable to apply a triple layer coating with a barrier layer solution (intermediate layer solution) interposed between the two solutions together with the application of the first solution and the second solution.

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

  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 absorptivity may be decreased), so it is necessary to set 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 layer thickness of the ink receiving layer needs to be determined in relation to the void ratio in the layer since it needs to have an absorption capacity sufficient to absorb all droplets when used for inkjet recording. For example, when the ink amount is 8 nL / mm ² and the porosity is 60%, the layer thickness is preferably about 15 μm or more.
Considering this point, when used for inkjet recording, the thickness of the ink receiving layer is preferably 10 to 50 μm.

Further, the pore diameter of the ink receiving layer is preferably 0.005 to 0.030 μm, more preferably 0.01 to 0.025 μm in terms of median diameter.
The porosity and pore median diameter can be measured using a mercury porosimeter (trade name “Bore Sizer 9320-PC2” manufactured by Shimadzu Corporation).

Further, the ink receiving layer is preferably excellent in transparency, but as a guide, the haze value when the ink receiving layer is formed on a transparent film support is preferably 30% or less, More preferably, it is 20% or less.
The haze value can be measured using a haze meter (HGM-2DP: Suga Test Instruments Co., Ltd.).

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

[Pigment ink]
The pigment ink is not particularly limited as long as it is an inkjet recording ink containing at least one pigment as a colorant. For example, at least one pigment, at least one water-soluble organic solvent, and water can be used.
The amount of the pigment contained in the pigment ink in the present invention is preferably 1 to 20% by mass, more preferably 2 to 12% by mass with respect to the entire pigment ink.

  The carbon black that can be used as a pigment contained in the black ink is preferably a furnace method, a channel method, or high specific surface area carbon produced by activating petroleum coke with a large amount of alkali. These carbon blacks have a primary particle size of 15 to 40 μm, a BET specific surface area of 50 to 3000 square m / g, a DBP oil absorption of 40 to 150 ml / 100 g, a volatile content of 0.5 to 10% by mass, Those having a pH of 2 to 9 are preferred.

  These carbon black pigments (CI Pigment Black 7) are No.2300, No.900, MCF-88, No.33, No.40, No.45, No.52, MA7, MA8, MA100, No.2200B (Mitsubishi Chemical Co., Ltd.); Raven 700, Raven 5750, Raven 5250, Raven 5000, Raven 3500, Raven 1255 (above Colombia); Regal 400R, Regal 330R, Regal 660R, Mogul L, Monarch 700 , Monarch 800, Monarch 880, Monarch 900, Monarch1000, Monarch 1100, Monarch 1300, Monarch 1400 (above, manufactured by Cabot); ColorBlack FW1, ColorBlack FW2, ColorBlack FW2V, ColorBlack FW18, ColorBlack FW200, ColorBlack S150, ColorBlack S160, ColorBlack S170, Printex 35, Printex U, Printex V, Printex 140U, Printex 140V, SpecialBlack 6, Special Black 5, Special Black 4A, Special Black 4, (above, manufactured by Degussa); MAXSORB G-40, MAXSORB G-15 , Maxsorb G-08 (manufactured by Kansai Thermochemical Co., Ltd.) can be used.

  The pigments used in yellow ink include CI Pigment Yellow 1, CI Pigment Yellow 2, CI Pigment Yellow 3, CI Pigment Yellow 12, CI Pigment Yellow 13, CI Pigment Yellow 14, CI Pigment Yellow 16, CI Pigment Yellow 17, CI Pigment Yellow 73, CI Pigment Yellow 74, CI Pigment Yellow 75, CI Pigment Yellow 83, CI Pigment Yellow 93, CI Pigment Yellow 95, CI Pigment Yellow 97, CI Pigment Yellow 98, CI Pigment Yellow 109, CI Pigment Yellow 110, CI Pigment Yellow 114, CI Pigment Yellow 128, CI Pigment Yellow 129, CI Pigment Yellow 151, CI Pigment Yellow 154, CI Pigment Yellow 155 and the like.

CI Pigment Red 5, CI Pigment Red 7, CI Pigment Red 12, CI Pigment Red 48 (Ca), CI Pigment Red 48 (Mn), CI Pigment Red 57 (Ca), CI Pigment Red 57: 1, CI Pigment Red 112, CI Pigment Red 122, CI Pigment Red 123, CI Pigment Red 168, CI Pigment Red 184, CI Pigment Red 202, and the like.
CI Pigment Blue 1, CI Pigment Blue 2, CI Pigment Blue 3, CI Pigment Blue 15: 3, CI Pigment Blue 15:34, CI Pigment Blue 16, CI Pigment Blue 22, CI Pigment Blue 60, CI Vat Blue 4, CI Vat Blue 60 and the like.

  The pigment ink in the present invention can be configured to include at least one pigment dispersing resin. The pigment-dispersing resin is preferably an alkali-soluble water-soluble resin because it can lower the viscosity of the dispersion and can be easily dispersed. The weight average molecular weight of these polymer dispersed resins is preferably 1000 to 30000, more preferably 3000 to 15000. By using a resin having a weight average molecular weight of 30000 or less, the viscosity of the pigment dispersion can be lowered, and when used in an ink jet recording system, it is advantageous in that the discharge characteristics are improved. Further, the use of a resin having a weight average molecular weight of 1000 or more is advantageous in that a sufficient dispersion effect due to steric hindrance can be obtained and the dispersion stability is improved.

  Specifically, hydrophobic monomers such as styrene, styrene derivatives, alkyl esters of acrylic acid, alkyl esters of methacrylic acid, and hydrophilic properties such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, fumaric acid, and derivatives thereof. Copolymers composed of functional monomers and their salts are preferred. The copolymer may have any structure such as random, block, and graft, and the acid value is preferably in the range of 20 to 400, more preferably 100 to 300. The amount of these water-soluble polymer-dispersed resins used is preferably in the range of pigment mass; dispersant mass = 10: 6 to 10: 0.5. The appropriate ratio is experimentally determined using the selected pigment and the water-soluble polymer resin, but the amount of the resin dissolved without adsorbing to the pigment should be 2% by mass or less in the ink. preferable.

  Basic substances for solubilizing the alkali-soluble resin in water include alkanols such as monoethanolamine, diethanolamine, triethanolamine, ethyl monoethanolamine, ethyldiethanolamine, monoisopropanolamine, diisopropanolamine, and triisopropanolamine. Organic amines such as amine and ammonia, or inorganic bases such as potassium hydroxide and sodium hydroxide can be used.

  The pigment as described above can be dispersed in an aqueous medium containing a water-soluble polymer using a known dispersion method.

  For the pigment ink in the present invention, an aqueous medium mainly composed of water and mixed with a water-soluble organic solvent can be used. The total amount of the water-soluble organic solvent is preferably 5 to 40% by mass with respect to the whole ink. In preparing the pigment ink, the selection of the solvent system is important in order to adjust the storage stability, moisture retention at the nozzle tip and fixability on the recording paper, and the boiling point of the solvent, volatility, viscosity, surface Adjustment can be made with sufficient consideration of the characteristics of the solvent such as tension and the content of the solvent.

  Preferred specific examples of the water-soluble organic solvent include ethylene glycol, diethylene glycol, triethylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, dimethyl sulfoxide, diacetone alcohol Glycerin monoallyl ether, propylene glycol, butylene glycol, polyethylene glycol 300, thiodiglycol, N-methyl-2-pyrrolidone, 2-pyrrolidone, γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, sulfolane, Trimethylolpropane, trimethylolethane, neopentyl glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether , Ethylene glycol monoallyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, β-dihydroxyethyl urea, urea, acetonyl Acetone, pentaerythritol, 1,4-cyclohexanediol, hexylene glycol, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, ethylene glycol monophenyl ether, diethylene glycol diethyl ether, diethylene glycol monobutyl ether, diethylene Glycol monoisobutyl ether, triethylene glycol monobutyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monopropyl ether , Dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, glycerin, glycerin monoacetate, glycerin diacetate, glycerin triacetate, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether acetate, cyclohexanol, 1 2-cyclohexanediol, 1-butanol, 3-methyl-1,5-pentanediol, 3-hexene-2,5-diol, 2,3-butanediol, 1,5-pentanediol, 2,4-pentanediol 2,5-hexanediol, ethanol, n-propanol, 2-propanol, 1-methoxy-2-propanol, furfuryl alcohol, tetrahydrofurfuryl alcohol and the like.

  In addition to the above materials, surfactants, preservatives, antioxidants, and other auxiliary materials for adjusting physical properties can be added to the pigment ink.

  Preferred specific examples of the surfactant include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenol ethers, polyoxyethylene alkyl esters, acetylene glycol compounds, sorbitan esters, sorbitan ester ethers, and oxyethyleneoxypropylene block polymers. Nonionic surfactants such as oxyethylene alkylamines, fatty acid alcohol amides, polyhydric alcohol fatty acid esters, acetylene glycol ethylene oxide adducts, etc .; dimethylalkyl (coconut) betaine, dimethylalkyllauryl betaine, alkylglycine Amphoteric surfactants such as amide betaine type and imidazoline type; octadecylamine acetate, tetradecylamine acetate, beef tallow alkyl propylene Diamine acetate, octadecyltrimethylammonium chloride, alkyl (tallow) trimethylammonium chloride, dodecyltrimethylammonium chloride, alkyl (palm) trimethylammonium chloride, hexadecyltrimethylammonium chloride, behenyltrimethylammonium chloride, alkyl (tallow) imidazolinone quaternary salt And cationic surfactants such as alkyldimethylbenzylammonium chloride, octadecyldimethylbenzylammonium chloride, dioleyldimethylammonium chloride, and polyoxyethylene dodecylmethylammonium chloride.

  These surfactants are used as necessary for the purpose of increasing the permeability to paper, the wettability with the discharge device member, the flow characteristics, and the auxiliary for dispersion stability.

  As a method for producing the ink, for example, first, a pigment dispersing resin is dissolved in an aqueous base solution, the pigment is added to the aqueous solution, the surface of the pigment is wetted by premixing, and then a dispersing machine such as a ball mill, a roll mill, or a sand mill is used. Use to disperse. Among them, a high-speed sand mill is preferable, and examples thereof include a super mill, a sand grinder, a bead mill, an agitator mill, a glen mill, a dyno mill, a pearl mill, and a cobol mill (all are trade names). The pigment dispersion thus prepared can be subjected to centrifugal separation and pressure filtration using a membrane to remove coarse particles, and a desired dispersion can be obtained. Next, the above-mentioned water-soluble organic solvent is added to this dispersion, and other additives (surfactant, pH adjuster, preservative, etc.) are added as necessary and stirred to obtain a recording ink.

  The recording ink has physical properties of pH 7 to 12, surface tension 20 to 60 dyn / cm (0.02 to 0.06 N / m), and viscosity 1 to 30 cps (0.001 to 0.03 Pa · s). It is preferable to adjust in the range.

  The preferred composition of the ink used in the present invention is that the pigment content is 2 to 12% by mass and the alkali-soluble water-soluble resin content is 0.1 to 7.2% by weight based on the whole ink. It is preferable that the content of the water-soluble organic solvent is 5 to 40% by mass, and other auxiliary materials such as surfactants, preservatives, and antioxidants are added as necessary.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, “part” and “%” are based on mass.

-Preparation of pigment ink-
(Preparation of black pigment dispersion)
A styrene / acrylic acid / ethyl acrylate copolymer (acid value 210, weight average molecular weight 9000, glass transition point 92 ° C.) was used as a pigment dispersing resin, and its aqueous ammonia solution (neutralization rate 150%, resin solid content 2.5). 15 parts by weight of carbon black (MCF-88, manufactured by Mitsubishi Chemical Corporation) washed with pure water is added to a solution consisting of 75 parts by mass, 5 parts of ethylene glycol, and 5 parts of ethyl alcohol, premixed, and then used with a sand mill. For 3 hours to prepare an aqueous dispersion. This dispersion was centrifuged with a centrifuge to remove coarse particles and the like to prepare a black pigment dispersion.

  A composition having the following composition was stirred for 3 hours and filtered through a 1 micron membrane filter, and then impurities such as calcium were removed through an ion exchange resin layer to obtain a desired black pigment ink.

(Black ink composition)
Black pigment dispersion obtained above 40 parts glycerin 10 parts polyethylene glycol 8 parts acetylenol EH (manufactured by Kawaken Fine Chemical Co., Ltd.) 1 part ion-exchanged water 41 parts

(Preparation of yellow pigment dispersion)
In the preparation of the black pigment dispersion, CI Pigment Yellow 74 was used instead of carbon black, and a styrene / acrylic acid / ethyl acrylate copolymer (acid value 180, weight average molecular weight 12000, glass transition point 75 ° C. as a pigment dispersion resin). A yellow pigment dispersion was prepared in the same manner as the black pigment dispersion except that a lithium hydroxide aqueous solution (a neutralization rate of 150% and a resin solid content of 2.5% by mass) was used.

(Preparation of yellow pigment ink)
In the preparation of the black pigment ink, a yellow pigment ink was prepared in the same manner as in the preparation of the black pigment ink except that 50 parts of the yellow pigment dispersion prepared above was used instead of the black pigment dispersion.

(Preparation of magenta pigment dispersion)
In the preparation of the black pigment dispersion, CI Pigment Red 122 was used instead of carbon black, and α-methylstyrene / styrene / acrylic acid / ethyl acrylate copolymer (acid value 210, weight average molecular weight 9000, glass, as a resin for pigment dispersion) A magenta pigment dispersion was prepared in the same manner as the above black pigment dispersion except that the transition point was 88 ° C.

(Preparation of magenta pigment ink)
In preparing the black pigment ink, a magenta pigment ink was prepared in the same manner as the black pigment ink except that 40 parts of the magenta pigment dispersion prepared above was used instead of the black pigment dispersion.

(Preparation of cyan pigment dispersion)
A cyan pigment dispersion was prepared in the same manner as the black pigment dispersion except that CI Pigment Blue 15: 3 was used instead of carbon black in the preparation of the black pigment dispersion.

(Preparation of cyan pigment ink)
In preparing the black pigment ink, a cyan pigment ink was prepared in the same manner as the black pigment ink except that 40 parts of the cyan pigment dispersion prepared above was used instead of the black pigment dispersion.
The physical properties of the produced pigment inks are shown below.

Black pigment ink pH 9.25, surface tension 33.4 mN / m, viscosity 3.5 mPa · s
Yellow pigment ink pH 8.80, surface tension 32.4 mN / m, viscosity 2.9 mPa · s
-Magenta pigment ink pH 9.10, surface tension 34.1 mN / m, viscosity 3.5 mPa.s
Cyan pigment ink pH 9.11, surface tension 33.2 mN / m, viscosity 3.1 mPa · s

<Example 1>
(Preparation of polymer solution P1)
12 mol maleic anhydride (MAA), 4 mol tall oil fatty acid, 5 mol polyoxyethylene allyl methyl ether (number average molecular weight (Mn) = 1,100 g / mol) and 5 mol polyoxypropylene monoallyl ether A copolymer C1 of monoacetate (number average molecular weight (Mn) = 1,600 g / mol) was prepared as follows.
7.2 g of tall oil fatty acid, 14.7 g (0.15 mol) of MAA, 68.9 g (0.0626 mol) of polyoxyethylene allyl methyl ether and 106 g (0.0663 mol) of polyoxypropylene monoallyl ether monoacetate The mixture was placed in a reaction vessel and heated to 137 ° C. with stirring. A solution prepared by dissolving 5.25 g of tert-butyl perbenzoate (TBPB) in 66 g of dipropylene glycol dimethyl ether was added dropwise over 4 hours. After completion of the addition, the mixture was further stirred at 137 ° C. for 0.5 hour to obtain the desired copolymer C1.
79 g of the obtained copolymer C1 was slowly added at 60 ° C. to a solution obtained by homogenizing 6.1 g of diethylethanolamine with 41 g of distilled water and 37.6 g of dipropylene glycol dimethyl ether. This mixture was further stirred at 60 ° C. for 15 minutes to obtain a polymer solution P1 containing a water-soluble comb structure polymer.

(Preparation of inkjet recording medium for pigment ink)
-Preparation of inorganic fine particle dispersion-
(1) Gas phase method silica fine particles having the following composition, (2) ion-exchanged water, and (3) Charol DC902P are mixed and dispersed using a non-media disperser (ultrasonic disperser manufactured by MSTAY Co., Ltd.). After that, the dispersion was heated to 45 ° C. and held for 20 hours.

[Composition of inorganic fine particle dispersion]
(1) Gas phase method silica fine particles (inorganic fine particles) 10 parts (AEROSIL300SF75 manufactured by Nippon Aerosil Co., Ltd.)
(2) Ion-exchanged water 62.8 parts (3) Charol DC-902P (dispersant, 51.5% aqueous solution) 0.87 parts (Daiichi Kogyo Seiyaku Co., Ltd.)

―Coating solution for forming ink receiving layer―
A composition comprising 50 parts of the above-mentioned inorganic fine particle dispersion in terms of solid content of silica and 50 parts of polyvinyl alcohol (PVA235, saponification degree 88%, manufactured by Kuraray Co., Ltd.) is dissolved and mixed in ion-exchanged water to obtain an ink receiving layer. A forming coating solution was prepared.
The obtained ink-receiving layer-forming coating liquid was coated on a polyethylene terephthalate film (trade name: Lumirror, thickness 100 μm, manufactured by Toray Industries, Inc.) as a support using a wire bar. After coating to a layer thickness of 10 μm, the ink receiving layer was formed on the support by drying at 120 ° C. for 3 minutes.
On the ink receiving layer obtained above, the polymer solution P1 obtained above was adjusted so that the solid content of the water-soluble comb structure polymer was 30% with respect to the coating solution for forming the ink receiving layer. It applied using the wire bar. Then, it dried for 5 minutes at 80 degreeC, and produced the inkjet recording medium for pigment inks.

<Example 2>
(Preparation of polymer solution P2)
12 mol of MAA, 8 mol of tall oil fatty acid, 3 mol of polyoxyethylene allyl methyl ether (number average molecular weight Mn = 1,100 g / mol) and 1 mol of polyoxypropylene monoallyl ether monoacetate (number average molecular weight Mn = 1,600 g / mol) of copolymer C2 was prepared as follows.
Reaction of a mixture of 14.4 g tall oil fatty acid, 27.1 g (0.2765 mol) MAA, 76 g (0.0692 mol) polyoxyethylene allyl methyl ether and 39 g (0.0244 mol) polyoxypropylene monoallyl ether monoacetate Placed in bath and heated to 137 ° C. with stirring. A solution prepared by dissolving 5.92 g of t-butyl perbenzoate (TBPB) in 74 g of dipropylene glycol dimethyl ether was added dropwise over 4 hours. After completion of the addition, the mixture was further stirred at 137 ° C. for 0.5 hour to obtain a copolymer C2. The solid content (SC) of the product containing the copolymer C2 was 75%.
66 g of the product containing the copolymer C2 obtained above was slowly added at 60 ° C. to a solution obtained by homogenizing 6 g of diethylethanolamine with 40 g of distilled water and 26.6 g of dipropylene glycol dimethyl ether. This mixture was further stirred at 60 ° C. for 15 minutes to obtain a polymer solution P2 containing a water-soluble comb structure polymer.

(Preparation of inkjet recording medium for pigment ink)
An ink jet recording medium for pigment ink was prepared in the same manner as in Example 1 except that the polymer solution P2 was used instead of the polymer solution P1.

<Example 3>
(Preparation of polymer solution P3)
50 g of the product containing copolymer C2 obtained in the same manner as in Example 2 was mixed with a solution obtained by homogenizing 4.1 g of diethylethanolamine and 12.8 g of oleylamine ethoxylate with 0.6 g of distilled water and 41 g of butyl glycol. Slowly added at 60 ° C. The mixture was further stirred at 60 ° C. for 15 minutes to obtain a polymer solution P3 containing a water-soluble comb structure polymer.

(Preparation of inkjet recording medium for pigment ink)
An ink jet recording medium for pigment ink was prepared in the same manner as in Example 1 except that the polymer solution P3 was used instead of the polymer solution P1.

<Example 4>
(Preparation of polymer solution P4)
13.2 mol MAA, 4.5 mol tall oil fatty acid, 4 mol polyoxyethylene allyl methyl ether (number average molecular weight Mn = 1,100 g / mol), 1.5 mol polyoxypropylene monoallyl ether mono A copolymer C3 of acetate (number average molecular weight Mn = 1,600 g / mol) and 2 mol of polyoxyethylene-polyoxypropylene-allylmethyl ether (EO / PO = 70/30, Mn = 1850 g / mol) is as follows: It produced as follows.
Tall oil fatty acid 26.1 g, MAA 26 g (0.265 mol), polyoxyethylene allyl methyl ether 88.4 g (0.08 mol), polyoxypropylene monoallyl ether monoacetate 48.2 g (0.03 mol) and A mixture of 72.3 g (0.039 mol) of polyoxyethylene-polyoxypropylene-allylmethyl ether was put in a reaction vessel and heated to 140 ° C. with stirring. 4.9 g of di-tert-butyl peroxide was added dropwise over 4 hours. After completion of the addition, the mixture was further stirred at 140 ° C. for 0.5 hour to prepare a copolymer C3.
The obtained copolymer C3 was designated as a polymer solution P4 containing a water-soluble comb structure polymer.

(Preparation of inkjet recording medium for pigment ink)
An ink jet recording medium for pigment ink was produced in the same manner as in Example 1 except that the polymer solution P4 was used instead of the polymer solution P1.

<Example 5>
(Preparation of polymer solution P5)
68 g of copolymer C3 obtained in the same manner as in Example 4 was slowly added at 60 ° C. to a homogenized solution of 8 g of diethylethanolamine and 114 g of distilled water. This mixture was further stirred at 60 ° C. for 30 minutes to prepare a polymer solution P5 containing a water-soluble comb structure polymer.

(Preparation of inkjet recording medium for pigment ink)
An ink jet recording medium for pigment ink was produced in the same manner as in Example 1 except that the polymer solution P5 was used instead of the polymer solution P1.

<Example 6>
(Preparation of inkjet recording medium for pigment ink)
An ink jet recording medium for pigment ink was prepared in the same manner as in Example 1, except that DispersBYK190 (manufactured by Big Chemie Japan Co., Ltd.) was used instead of the polymer solution P1.

<Example 7>
(Preparation of inkjet recording medium for pigment ink)
An ink jet recording medium for pigment ink was produced in the same manner as in Example 1 except that DispersBYK194 (manufactured by Big Chemie Japan Co., Ltd.) was used instead of the polymer solution P1.

<Example 8>
(Preparation of inkjet recording medium for pigment ink)
In Example 1, DisperBYK194 (manufactured by Big Chemie Japan Co., Ltd.) was added and mixed in the ink receiving layer forming coating solution so that the solid content of the water-soluble comb structure polymer was 30%. A coating solution was prepared. The obtained ink-receiving layer-forming coating liquid was coated on a polyethylene terephthalate film (trade name: Lumirror, thickness 100 μm, manufactured by Toray Industries, Inc.) as a support using a wire bar. After coating so as to have a layer thickness of 15 μm, it was dried at 120 ° C. for 3 minutes to form an ink-receiving layer on the support to produce an ink jet recording medium for pigment ink.

<Comparative Example 1>
(Preparation of inkjet recording medium for pigment ink)
In Example 1, an ammonia aqueous solution (neutralization rate 150%) of a styrene / acrylic acid / ethyl acrylate copolymer (weight average molecular weight 9000, glass transition temperature 92 ° C.) was used instead of the polymer solution P1. In the same manner as in Example 1, an inkjet recording medium for pigment ink was produced.

<Comparative example 2>
(Preparation of inkjet recording medium for pigment ink)
An ink jet recording medium for pigment ink was produced in the same manner as in Example 1 except that the polymer solution P1 was not applied on the ink receiving layer.

[Evaluation]
Next, using the ink jet recording medium for pigment ink and the pigment ink obtained above, a color image is formed by a recording apparatus equipped with an ink jet recording head that ejects ink droplets by the action of heat having a recording nozzle of 600 DPI. The formed images were evaluated as follows.

<Black solid density>
A black solid image was printed on each of the pigment ink inkjet recording media obtained above, and the optical density was measured using an optical densitometer X-Rite MODEL310TR (manufactured by X-Rite). The results are shown in Table 1.

<Abrasion resistance>
Each pigment ink inkjet recording medium was printed at the highest density of black, yellow, magenta, and cyan, and cut into A4 size sheets. Two ink jet recording media for pigment ink cut to A4 size were superposed on a horizontal and flat test table. At this time, the sheets are overlaid so that the ink receiving layer surface of the lower sheet and the back surface of the upper sheet are in contact with each other. While applying a load of 500 g / A4 size on the upper upper sheet, the lower sheet was pulled out at a speed of 1 cm / second, and scratches formed on the surface of the ink receiving layer of the lower sheet were evaluated according to the following evaluation criteria. evaluated. The results are shown in Table 1.

~Evaluation criteria~
AA: No scratch was observed.
A: Slight scratching was observed.
B: Scratches were observed, but there was no practical problem.
C: Scratches could be clearly observed and there was a problem in practical use.

<Bronze>
A cyan solid image having the maximum density was printed on the ink jet recording medium for each pigment ink obtained above. It observed visually and evaluated according to the following evaluation criteria. The results are shown in Table 1.

~Evaluation criteria~
AA: Almost no confirmation was possible.
A: Slightly confirmed.
B: Although confirmed, there was no problem in practical use.
C: Clearly confirmed and practically problematic.

<Glossiness>
For each ink-jet recording medium for pigment ink, the 75-degree specular gloss of the white background (conforming to JIS Z8741) and the 75-degree specular gloss of solid images of each color of Y, M, C, R, G, B, and Bk The average value was obtained, the difference between both gloss values was calculated, and evaluated according to the following evaluation criteria. The results are shown in Table 1.

~Evaluation criteria~
AA: The difference in gloss value was less than 5.
A: The difference in glossiness value was 5 or more and less than 15 (no problem in practical use).
B: The difference in glossiness value was 15 or more and less than 20 (practical limit).
C: The difference in glossiness value was 20 or more (problematically problematic).

  From Table 1, it can be seen that the inkjet recording medium for pigment ink of the present invention has a high black solid density, excellent scratch resistance, bronze suppression, and good glossiness.

Claims (2)

  A pigment having at least one ink-receiving layer containing a pigment and a binder on a support, wherein the outermost surface layer farthest from the support of the ink-receiving layer contains at least one water-soluble comb structure polymer Inkjet recording medium for ink. The water-soluble comb-type structure polymer comprises a copolymer comprising (a) an ethylenically unsaturated 1,2-dicarboxylic acid derivative, (b) an unsaturated monocarboxylic acid derivative, and (c) a polyalkyleneoxyallyl ether; At least one selected from the group consisting of the copolymer and a reaction product of at least one selected from ammonia, amine, water, alcohol, amino alcohol, alkali metal hydroxide, and alkaline earth metal hydroxide. The inkjet recording medium for pigment ink according to claim 1, wherein the inkjet recording medium is a pigment ink.