JP2008246756A - Inkjet recording medium and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording medium which suppresses wet heat blurring in an ink accepting layer using pseudo-boehmite-like alumina hydrate and makes it possible to record an image having a high density and superior resistances to ozone and light. <P>SOLUTION: The ink accepting layer which the medium has on a water-resistant substrate contains the pseudo-boehmite-like alumina hydrate, polyvinyl alcohol having a saponification degree less than 90% and an average polymerization degree of 3,000 or more, a crosslinking agent for crosslinking the polyvinyl alcohol, a cationic polymer including quaternary ammonium in the skeleton, a water-soluble manganese compound and ammonium sulfate. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ink jet recording medium suitable for recording an image by applying ink by an ink jet method and a method for producing the same.

  With the rapid development of the information technology industry in recent years, various information processing systems have been developed, and recording methods and recording apparatuses suitable for each information processing system have been put into practical use. Among these, the ink jet recording method is widely used because it can record on various recording materials, the hardware (device) is relatively inexpensive and compact, and has excellent quietness. ing. In the recording using the ink jet recording method, it has become possible to obtain a so-called photographic-like high quality recorded matter.

  In general, recording materials for inkjet recording are (1) fast-drying (high ink absorption speed), (2) proper and uniform dot diameter (no bleeding), (3) granular (4) High dot roundness, (5) High color density, (6) High saturation (no dullness), (7) Water resistance of the image area (8) High whiteness, (9) High storage stability (no yellowing or image blurring after long-term storage), (10) It is required to have properties such as being hard to deform and having good dimensional stability (low curl) and (11) good hard running performance.

  In view of the above, in recent years, recording materials in which the ink receiving layer has a porous structure have been put into practical use. According to this, it is said that it is excellent in quick-drying and high gloss is obtained. However, there is a tendency for the quality of a recorded image to be constantly high, and in particular, there are severe requirements for image storability (light resistance, gas resistance, etc.), color density, and hue. For example, it is important that the high density region is dark in terms of image contrast and contrast, and that no bronzing occurs in terms of hue and color.

In relation to the above, a recording medium in which a porous ink receiving layer containing an alumina hydrate and a binder contains a water-soluble manganese compound and ammonium sulfate has been disclosed, and the light resistance and gas resistance of an ink image can be improved. (For example, refer to Patent Document 1). In this document, when a water-soluble manganese compound having the highest gas resistance among the metal salts is used, the light resistance and gas resistance of the printed part are improved, while the photooxidation and oxidizing gas of the manganese compound itself are improved. In view of the problem that browning occurs in the non-printing part (white part), ammonium sulfate is used in combination with the water-soluble manganese compound. This ammonium sulfate is used to suppress browning of non-printing parts (white parts) derived from manganese compounds.
JP2004-209650

  However, in the above-mentioned recording medium configuration, there is no specific description of the crosslinking agent and gelation can be achieved even if the light resistance and gas resistance improvement effect by using the water-soluble manganese compound and ammonium sulfate is obtained to some extent. Therefore, there is no specific description of a low-polar cationic polymer that adsorbs and immobilizes the dye, it does not bleed well with heat, has a high concentration and good color for a long period of time. A quality image is not obtained.

  Further, when trying to improve the light resistance and ozone resistance of an image, the image density generally tends to decrease, and the compatibility between the storage stability and the density with respect to light and ozone gas is one of the conventional problems.

  The present invention has been made in view of the above, suppresses the occurrence of wet heat bleeding in the ink receiving layer using pseudoboehmite-like alumina hydrate, and has an overwhelmingly high concentration compared to gas phase method silica and the like. It aims at providing the inkjet recording medium which can record the image excellent in ozone resistance and light resistance, and makes it a subject to achieve the objective.

  The present invention is based on the knowledge that there is a correlation between wet heat bleeding and ozone resistance and light resistance in an image portion recorded with ink, and between ozone resistance and light resistance and image density. is there. The present invention is technically compatible with technical matters that are mutually contradictory, has light resistance and ozone resistance while obtaining a high concentration, and also prevents wet heat bleeding.

Specific means for achieving the above object are as follows.
<1> On a water-resistant support, pseudoboehmite-like alumina hydrate, polyvinyl alcohol having a saponification degree of less than 90% and an average polymerization degree of 3000 or more, a crosslinking agent that crosslinks at least polyvinyl alcohol, and quaternary ammonium. An ink jet recording medium having an ink receiving layer containing a cationic polymer contained in a skeleton, a water-soluble manganese compound, and ammonium sulfate.

<2> The inkjet recording medium according to <1>, wherein at least one of the crosslinking agents is boric acid and / or a salt thereof.
<3> The ink jet recording medium according to <1> or <2>, wherein the ink receiving layer includes a plurality of layers, and the uppermost layer includes colloidal silica.

<4> The <1> to <3, wherein a mass ratio (al / PVA) of the pseudoboehmite-like alumina hydrate (al) and the polyvinyl alcohol (PVA) is 7.5 to 13. The inkjet recording medium according to any one of the above.
<5> The inkjet recording medium according to any one of <1> to <4>, wherein the cationic polymer has a polyurethane skeleton.

  <6> On a water-resistant support, pseudoboehmite-like alumina hydrate, polyvinyl alcohol having a saponification degree of less than 90% and a polymerization degree of 3000 or more, a cross-linking agent that cross-links at least polyvinyl alcohol, and quaternary ammonium as a skeleton The ink-receiving layer is formed by applying a preparation solution prepared by mixing a cationic latex, a water-soluble manganese compound, and ammonium sulfate.

  <7> A step of preparing an alumina dispersion in which the pseudo boehmite-like alumina hydrate is dispersed in an aqueous solvent, the alumina dispersion, an aqueous solution containing the polyvinyl alcohol, the crosslinking agent, the cationic latex, and the water solution. And a step of preparing a coating liquid by mixing a water-soluble manganese compound and the ammonium sulfate, and a step of forming an ink-receiving layer by coating the prepared coating liquid on a water-resistant support. The method for producing an inkjet recording medium according to <6>.

  According to the present invention, an ink jet recording medium capable of recording images with high density and excellent ozone resistance and light resistance by suppressing the occurrence of wet heat bleeding in the ink receiving layer using pseudoboehmite-like alumina hydrate. Can be provided.

Hereinafter, the ink jet recording medium of the present invention will be described in detail.
The ink jet recording medium of the present invention is constituted by providing at least one ink receiving layer on a water-resistant support (hereinafter also simply referred to as a support), and a plurality of layers can be provided as necessary. At least one layer of the ink receiving layer is composed of pseudoboehmite-like alumina hydrate, polyvinyl alcohol having a saponification degree of less than 90% and an average polymerization degree of 3000 or more, a crosslinking agent that crosslinks at least polyvinyl alcohol, and quaternary ammonium. It comprises a cationic polymer containing, a water-soluble manganese compound, and ammonium sulfate (hereinafter, this layer may be referred to as “ink receiving layer in the present invention”), and if necessary, contains other components. But you can.
Further, when a plurality of layers are provided on the water-resistant support, a layer using colloidal silica as the outermost layer farthest from the water-resistant support may be provided together with the ink receiving layer in the present invention. it can.

  In the present invention, when the ink-receiving layer is formed using pseudo boehmite-like alumina hydrate, the haze is lowered after the ink solvent penetrates (that is, after recording) using PVA having a relatively low saponification degree. In addition, the use of a cationic polymer containing quaternary ammonium as a skeleton, a water-soluble manganese compound, and ammonium sulfate together suppresses the generation of wet heat and the resistance to light and ozone gas in the image. (That is, light resistance and ozone resistance) can be effectively improved.

When the inkjet recording medium of the present invention has two or more layers on the water-resistant support, for example, (1) it has two or three or more “ink receiving layers in the present invention” on the water-resistant support. An ink jet recording medium, and (2) an ink jet recording medium having one or two or more “ink receiving layers in the present invention” and an uppermost layer containing colloidal silica in order from the water resistant support side on the water resistant support. included.
The ink receiving layer in the present invention is a layer mainly containing inorganic fine particles mainly composed of pseudoboehmite-like alumina hydrate, and the uppermost layer can be constituted as a layer mainly containing colloidal silica.
Here, “mainly containing inorganic fine particles” means that the content with respect to the total solid content constituting the ink receiving layer is 50% by mass or more. This content is preferably 60% by mass or more, particularly preferably 65% by mass or more.

Hereinafter, each component constituting the ink receiving layer will be described in detail.
-Pseudo boehmite-like alumina hydrate-
The ink receiving layer in the invention contains at least one kind of pseudo boehmite-like alumina hydrate. By being composed of alumina hydrate, the transparency of the layer is improved, and a high-density image can be recorded. Further, the ink absorbability and the absorption speed can be improved.

The pseudo boehmite-like alumina hydrate in the present invention is represented by a constitutional formula of Al ₂ O ₃ .nH ₂ O (1 <n <3), and the alumina hydrate when n is greater than 1 and less than 3. Sure.

  The average pore radius of the alumina hydrate is preferably 1 to 10 nm, and particularly preferably 2 to 7 nm, from the viewpoint of improving the ink absorption rate of the ink receiving layer. When the average pore radius is within the above range, the ink absorptivity is good, the fixing of the dye in the ink is good, and the occurrence of image bleeding can be avoided.

The pore volume of the alumina hydrate is preferably in the range of 0.1 to 0.8 ml / g, particularly in the range of 0.4 to 0.6 ml / g from the viewpoint of improving the ink absorption capacity of the ink receiving layer. A range is preferred. When the pore volume of the ink receiving layer is within the above range, it is possible to avoid the occurrence of cracks and powder falling in the ink receiving layer, and the ink absorption is improved. The pore volume at a pore radius of 2 nm to 10 nm is preferably 0.1 ml / g or more. Within this range, the adsorption of the dye in the ink becomes good. Further, the solvent absorption amount per unit area of the ink receiving layer is preferably 5 ml / m ² or more, and particularly preferably 10 ml / m ² or more. When the solvent absorption amount per unit area is within the above range, it is possible to prevent ink overflow particularly when multicolor printing is performed.

In order for the alumina hydrate to sufficiently absorb and fix the dye in the ink, the BET specific surface area of the alumina hydrate is preferably in the range of 70 to 300 m ² / g. When the BET specific surface area is within the above range, the alumina hydrate can be dispersed well, the pore size distribution is not deviated, the fixing efficiency of the dye in the ink is improved, and image bleeding can be avoided.

In order to increase the concentration of the alumina hydrate dispersion, the number of surface hydroxyl groups of the alumina hydrate is preferably 10 ²⁰ / g or more. When the number of surface hydroxyl groups is small, the alumina hydrate tends to aggregate and it is difficult to increase the concentration of the dispersion.

  In order to stabilize the dispersion of alumina hydrate, various acids are usually added to the dispersion. Examples of such acids include nitric acid, hydrochloric acid, hydrobromic acid, acetic acid, formic acid, ferric chloride, aluminum chloride and the like, but the present invention is not limited thereto.

  The alumina hydrate can be produced by a known method such as hydrolysis of aluminum alkoxide such as aluminum isopropoxide, neutralization of aluminum salt with alkali, hydrolysis of aluminate. The particle size, pore size, pore volume, specific surface area, number of surface hydroxyl groups, etc. of the alumina hydrate can be controlled by the precipitation temperature, aging time, solution pH, solution concentration, coexisting salts and the like.

  For example, JP-A-57-88074, JP-A-62-56321, JP-A-4-275717, JP-A-6-64918, JP-A-7-10535, JP-A-7-267633, US Pat. 2,656,321, Am. Ceramic Soc. Bull. , 54, 289 (1975), etc. disclose a method for hydrolyzing aluminum alkoxide. These aluminum alkoxides include isopropoxide, propoxide, 2-butoxide and the like. By this method, a highly pure alumina hydrate can be obtained.

  In addition, as a method for obtaining alumina hydrate, as disclosed in JP-A Nos. 54-116398, 55-23034, 55-27824, 56-120508, etc., aluminum Generally, a method for obtaining an inorganic salt or a hydrate thereof as a raw material. Examples of these inorganic salts include inorganic salts such as aluminum chloride, aluminum nitrate, aluminum sulfate, polyaluminum chloride, ammonium alum, sodium aluminate, potassium aluminate, aluminum hydroxide, and hydrates of these inorganic salts. Etc.

  Specifically, for example, an alumina hydrate is obtained by a neutralization reaction between an aqueous solution of an acidic aluminum salt such as aluminum sulfate, aluminum nitrate, or aluminum chloride and a basic aqueous solution such as sodium aluminate, sodium hydroxide, or aqueous ammonia. Can be manufactured. In this case, it is common to mix within a range where the amount of alumina hydrate produced in the liquid does not exceed 5% by mass, and to react under conditions of pH 6 to 10 and temperature 20 to 100 ° C. Further, as described in JP-A-56-120508, a method for growing alumina hydrate crystals by alternately changing the pH to the acid side and the base side, aluminum described in JP-B-4-33728 It can also be produced by a method of rehydrating alumina by mixing alumina hydrate obtained from the inorganic salt and alumina obtained by the Bayer method.

  The average particle diameter (average primary particle diameter) of primary particles of alumina hydrate is preferably 5 to 50 nm. In order to obtain higher gloss, a plate-like or rod-like particle having an average primary particle diameter of 5 to 20 nm and an average aspect ratio (ratio of average particle diameter to average thickness) of 2 or more is used. Is preferred.

The average primary particle diameter of the alumina hydrate may be a nominal value of a commercial product manufacturer.
When measuring the average primary particle size from the prepared recording medium, after removing the ink receiving layer, removing the resin component with hot water, and then collecting only the particles by centrifugation, etc. The obtained particles can be obtained by observation with a TEM (transmission electron microscope). At this time, for example, the same processing is performed on a sample coated with only the ink receiving layer coating solution as a reference sample, and the known particle diameter (nm) of the alumina hydrate particles using the measured value (average value) is used. The average primary particle diameter in the produced recording medium can be determined by comparing and converting the measured value (average value) in the produced recording medium from the difference between the values obtained by the comparison. In addition, in order to obtain | require an average primary particle diameter, about 100-3000 particles are required as a measurement particle number.

  The content of the pseudo boehmite-like alumina hydrate in the ink receiving layer is preferably 10 to 25% by mass, and more preferably 13 to 20% by mass. When the content of the pseudo boehmite-like alumina hydrate is within the above range, the viscosity stability of the coating liquid after preparation is good and preferable.

-Polyvinyl alcohol-
The ink receiving layer in the invention contains at least one polyvinyl alcohol (PVA) having a saponification degree of less than 90% and an average polymerization degree of 3000 or more as a water-soluble binder. This PVA can be used as an aqueous solution in which one or more of them are dissolved in an aqueous solvent. As the aqueous solvent, water such as pure or ion-exchanged water, or a mixed solvent of water and an organic solvent soluble in the water can be used, and details will be described later.

When the degree of saponification of PVA is 90% or more, gelation with alumina hydrate tends to occur, the haze of the image receiving layer tends to increase, and the image receiving layer haze after printing with dye ink tends to increase. Since it is difficult to increase the concentration, the saponification degree must be less than 90%. Among these, polyvinyl alcohol having a saponification degree of 75 or more and less than 90% is preferable. By setting the degree of saponification to 75% or more, the coating film strength can be obtained and cracks can be prevented, and by making it less than 90, a high image density can be obtained. Furthermore, polyvinyl alcohol having a saponification degree of 85 or more and less than 90% is preferable from the viewpoint of preventing the occurrence of bronzing.
Incidentally, bronzing refers to a phenomenon in which the applied ink does not soak into the ink receiving layer and solidifies on the surface so that the image appears bronze (especially, the cyan image portion has a reddish brown color).

  When the average degree of polymerization of PVA is less than 3000, the mixing with the alumina hydrate, the adjustment of the coating liquid viscosity, and the film forming property are deteriorated, the image density is lowered, and the coating strength is reduced. Not enough cracks occur. Further, the haze after printing of the water-soluble dye ink is likely to increase, and the printing density is lowered, so PVA having an average polymerization degree of 3000 or more must be contained. Among these, polyvinyl alcohol in the range of 3000 to 5000 is preferable. By setting the average polymerization degree to 5000 or less, the viscosity stability of the coating solution can be imparted. The molecular weight can be determined from the product of the average degree of polymerization and the formula weight of the monomer.

  The degree of saponification can be obtained by reacting residual acetic acid groups in PVA with a known amount of sodium hydroxide and determining the saponification ratio in PVA from the amount of sodium hydroxide consumed.

  Examples of polyvinyl alcohol (PVA) include modified PVA such as cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, silanol-modified polyvinyl alcohol, and polyvinyl acetal derivatives such as polyvinyl acetal.

Moreover, in this invention, it is preferable to make the mass ratio (al / PVA) of the said pseudo boehmite-like alumina hydrate (al) and polyvinyl alcohol (PVA) into the range of 7.5-13. By setting the mass ratio al / PVA within the above range, haze can be suppressed and high image density and gloss can be obtained.
The mass ratio al / PVA is 8 to 11 in that it suppresses haze and maintains high image density and gloss, while maintaining mixing with alumina hydrate, adjustment of coating liquid viscosity, and film formability. A range is more preferred.

Along with polyvinyl alcohol (PVA), one or more water-soluble binders other than PVA may be used in combination.
Examples of the water-soluble binder include starch and modified products thereof, gelatin and modified products thereof, casein, pullulan, gum arabic, karaya gum, albumin and other natural polymer resins or derivatives thereof, cation modification, SBR latex, NBR latex. , Latexes such as methyl methacrylate-butadiene copolymer, ethylene-vinyl acetate copolymer, vinyl polymers such as polyacrylamide, polyvinyl pyrrolidone, polyethyleneimine, polypropylene glycol, polyethylene glycol, maleic anhydride or copolymers thereof. Can be mentioned.

  As content in the coating liquid of polyvinyl alcohol (PVA), the inside of the range of 7-14 mass% is preferable with respect to pseudo-boehmite-like alumina hydrate, and the inside of the range of 8-12 mass% is more preferable. When the amount of PVA is within the above range, film formation by coating is easy, cracks and powder falling of the coating film can be avoided, and ink absorbability is improved.

-Crosslinking agent-
The ink receiving layer in the present invention contains at least one crosslinking agent that crosslinks polyvinyl alcohol and other water-soluble binders contained as necessary. By containing a crosslinking agent, PVA and the water-soluble binder contained as needed can be crosslinked and hardened. Accordingly, the film strength, film formability, and water resistance of the ink receiving layer formed using pseudo boehmite-like alumina hydrate can be improved.

  The crosslinking agent can be used as an aqueous solution in which one or more of them are dissolved in an aqueous solvent. As the aqueous solvent, water such as pure or ion-exchanged water, or a mixed solvent of water and an organic solvent soluble in the water can be used, and details will be described later.

What is necessary is just to select suitably a crosslinking agent suitably with respect to PVA contained in an ink receiving layer, and the water-soluble binder contained as needed. Among these, boric acid and / or a salt thereof is preferable in the ink receiving layer according to the invention containing PVA in that the crosslinking reaction is rapid. For example, orthoboric acid, metaboric acid, hypoboric acid and the like can be used as boric acid, and these soluble salts are preferable as boric acid salts. Specifically, Na ₂ B ₄ O ₇ · 10H ₂ O, NaBO _{2 · 4H 2 0, K 2} B 4 O 7 · 5H 2 O, NH 4 HB 4 O 7 · 3H 2 O, NH 4 BO 2 , and the like. However, the present invention is not limited to these.

When gelatin is used in combination with PVA as a water-soluble binder, the following compounds other than boric acid and its salts can also be used as a crosslinking agent.
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; 1,6- Isocyanate compounds such as 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; Epoxys such as glycerol triglycidyl ether Compounds; ethyleneimino compounds such as 1,6-hexamethylene-N, N′-bisethyleneurea; halogenated carboxaldehyde compounds such as mucochloric acid and mucophenoxycyclolic acid; dioxane such as 2,3-dihydroxydioxane Compounds: titanium lactate, aluminum sulfate, chromium alum, potash alum, metal-containing compounds such as zirconyl acetate and chromium acetate, polyamine compounds such as tetraethylenepentamine, hydrazide compounds such as adipic acid dihydrazide, oxazo A low molecule or polymer containing two or more phosphorus groups. A crosslinking agent may be used alone or in combination of two or more.

A crosslinking agent (preferably boric acid and / or a salt thereof) may be used alone or in combination of two or more.
The total content of the crosslinking agent in the ink receiving layer is preferably 5 to 40 parts by mass, and more preferably 15 to 35 parts by mass with respect to 100 parts by mass of the total amount of PVA and other water-soluble binders. When the content of the crosslinking agent is within the above range, it is effective for preventing cracks and the like.
In the case of using boric acid and / or its salt, the total amount of boric acid and / or salts thereof is _preferably 5 to 40 mass% with respect to PVA in H 3 BO ₃ in terms, more preferably 15 to 35 weight% It is. By making the total amount within the above range, it is possible to improve film formability and water resistance while suppressing an increase in the viscosity of the coating solution to be prepared.

-Cationic polymer-
The ink receiving layer in the invention contains at least one cationic polymer containing quaternary ammonium in the skeleton. When an alumina hydrate is contained as in the ink-receiving layer in the present invention, good crack resistance and water resistance can be obtained without necessarily using a cationic compound, but the present invention contains this cationic polymer. As a result, it is possible to effectively suppress the occurrence of wet heat bleeding of the recorded image.

  In this case, by providing a layer (for example, the uppermost layer) containing colloidal silica and a cationic polymer on the ink receiving layer containing the cationic polymer, scratch resistance, water resistance, and ink absorbability can be further improved. Aggregation at the interface between the two layers is prevented, and as a result, uneven coating and uneven gloss can be eliminated.

  Examples of the cationic polymer include polydiallyldimethylammonium chloride, diallyldimethylammonium chloride derivatives, quaternary ammonium salt type cationic polymers containing a polyurethane skeleton, acrylic esters, and quaternary ammonium salt type cations containing an acrylic ester derivative skeleton. It can be selected from compounds containing quaternary ammonium in the polymer skeleton such as polymers. Preferably, it is a cationic polymer having a polyurethane skeleton with a low polarity (hereinafter referred to as a cationic polyurethane) from the viewpoint that the effect of preventing the occurrence of wet heat bleeding is high. “Polarity” as used herein refers to, for example, a so-called I / O value, and is a parameter indicating a measure of hydrophilicity / new oiliness of a compound or a substituent. (Organic conceptual diagram; Yoshio Koda, Sankyo Publishing) (1984) has a detailed explanation. I is inorganic, O is organic, and the larger I / O is, the higher the inorganicity (the higher the polarity and the higher the hydrophilicity). The I / O value of the cationic polymer used in the present invention is preferably less than 2.4, more preferably less than 2.1, considering the suppression of the occurrence of wet heat bleed, and in terms of greatly improving the wet heat bleed, Less than 1.8 is highly preferred.

  By containing the cationic polyurethane in the ink receiving layer, it is effective in improving wet heat blur of the image, water resistance and curling prevention.

  The cationic polyurethane is not particularly limited, and known ones can be used. Examples thereof include cationic polyurethanes obtained by the following preparations (1), (2) and the like. In particular, a composition in which cationic polyurethane is dispersed in water, that is, an aqueous dispersion is preferable.

Preparation of the cationic polyurethane
(1) Polyester polyol (B1) is used as a polyol for urethane reaction with polyisocyanate (A), and a urethane prepolymer is prepared using a chain extender (C) having a tertiary amino group. Cationic polyurethane can be obtained in the form of a composition by neutralizing a part of the group with an acid or quaternizing with a quaternizing agent so that the amine value is in the range of 1 to 40 (KOHmg / g). . Also,
(2) Polycarbonate polyol (B2), chain extender (C) having a tertiary amino group, and polyalkylene oxide (D) containing 50% by mass or more of an ethylene oxide chain, using the polyisocyanate (A) A cationic polyurethane can be obtained by preparing a urethane prepolymer and neutralizing the tertiary amino group introduced by the chain extender (C) with an acid or quaternizing with a quaternizing agent. By making the cationic polyurethane into a form dispersed in water, an aqueous dispersion can be obtained.

Hereinafter, the preparation (1) will be described.
As the polyisocyanate (A), conventionally used polyisocyanates such as aliphatic, alicyclic, aromatic and araliphatic can be used.
These polyisocyanates can be used alone or in combination of two or more.

  Specific examples of the aliphatic polyisocyanate include tetramethylene diisocyanate, dodecamethylene diisocyanate, 1,4-butane diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate. Lysine diisocyanate, 2-methylpentane-1,5-diisocyanate, 3-methylpentane-1,5-diisocyanate and the like.

  Specific examples of the alicyclic polyisocyanate include isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, 1,4-cyclohexane diisocyanate, methylcyclohexylene diisocyanate, 1,3-bis (isocyanate methyl). A cyclohexane etc. can be mentioned.

  Specific examples of the aromatic polyisocyanate include tolylene diisocyanate, 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, 4, Examples include 4′-dibenzyl diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, and the like.

  Specific examples of the araliphatic polyisocyanate include dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, α, α, α, α-tetramethylxylylene diisocyanate and the like.

  Although the said polyester polyol (B1) can use what is comprised by various polycarboxylic acid and polyol, it is comprised by the dicarboxylic acid and aliphatic glycol which consist of an aliphatic dibasic acid and an aromatic dibasic acid. A thing is more preferable at the point that adhesiveness becomes high. Examples of the aliphatic dibasic acid include malonic acid, succinic acid, tartaric acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, alkyl succinic acid, linolenic acid, maleic acid, fumaric acid , Mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, etc., or reactive derivatives thereof such as acid anhydrides, alkyl esters, acid halides, and the like. These aliphatic dicarboxylic acids can be used alone or in combination of two or more. Examples of the aromatic dibasic acid include phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, tetrahydro Examples thereof include phthalic acid and the like, or reactive derivatives thereof such as acid anhydrides, alkyl esters, and acid halides. These aromatic dicarboxylic acids can be used alone or in combination of two or more.

  Examples of the aliphatic glycol include ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 1,6- Hexanediol, propylene glycol and the like can be exemplified, and these may be used alone or in combination of two or more.

  The chain extender (C) having a tertiary amino group in the molecule is used for introducing the tertiary amino group into the urethane prepolymer. Examples of such chain extender (C) include N-alkyldialkanolamines such as N-methyldiethanolamine and N-ethyldiethanolamine, N-alkyldiaminoalkyls such as N-methyldiaminoethylamine and N-ethyldiaminoethylamine. Examples thereof include amines and triethanolamine. These chain extenders (C) having a tertiary amino group can be used singly or in combination of two or more.

  The addition amount of the chain extender (C) in the preparation (1) is 5 to 20% by mass with respect to the total amount of the polyisocyanate (A), the polyester polyol (B1) and the chain extender (C). More preferred. When the added amount of the chain extender (C) is 5% by mass or more, the introduced tertiary amino group is sufficient, and adhesion and water resistance of the ink can be obtained. Further, when the addition amount of the chain extender (C) is 20% by mass or less, the adhesion and ink water resistance improvement effect corresponding to the addition amount can be obtained, and also effective in terms of ease of preparation. It is.

  The content of free NCO at the end of the urethane prepolymer produced by the reaction of the polyisocyanate (A), the polyester polyol (B1), and the chain extender (C) having a tertiary amino group in the molecule is 1 to A range of 5% by mass is more preferable. When the content of the terminal free NCO is 1% by mass or more, it is easy to prepare a urethane prepolymer, and when it is 5% by mass or less, the cohesive force of the obtained water-based polyurethane resin can be kept low. This is preferable.

  A cationic urethane prepolymer in which the tertiary amino group introduced by the chain extender (C) and a part thereof are neutralized with an acid or quaternized with a quaternizing agent is prepared. When the tertiary amino group and a part thereof are neutralized with an acid, the acids include formic acid, acetic acid, propionic acid, butyric acid, lactic acid, malic acid, malonic acid, adipic acid and other organic acids, and hydrochloric acid, phosphoric acid, Mention may be made of inorganic acids such as nitric acid. These acids can be used alone or in combination of two or more.

  In addition, when quaternizing a tertiary amino group and a part thereof with a quaternizing agent, quaternizing agents include alkyl halides such as benzyl chloride and methyl chloride, sulfate esters such as dimethyl sulfate and diethyl sulfate. Etc. These quaternizing agents can be used alone or in combination of two or more.

  As described above, the tertiary amino group and a part thereof are not completely neutralized or quaternized, and only a part of the tertiary amino group is neutralized or quaternized. The amount of the tertiary amino group remaining without being neutralized or quaternized is an amount such that the amine value of the cationic polyurethane is 1 to 40 (KOHmg / g). It can be adjusted by quaternization.

Next, the preparation (2) will be described.
The polyisocyanate (A) used in the preparation (2) is the same as the polyisocyanate (A) used in the preparation (1) and is as described above.
Examples of the polycarbonate polyol (B2) used in the preparation (2) include compounds obtained by reacting glycols such as 1,4-butanediol, 1,6-hexanediol, and diethylene glycol with diphenyl carbonate and phosgene. Is mentioned. These aromatic dicarboxylic acids can be used singly or in combination of two or more.

  The addition amount of the polycarbonate polyol (B2) is in the range of 40 to 80% by mass with respect to the total amount of the polyisocyanate (A), the polycarbonate polyol (B2), the chain extender (C), and the polyalkylene oxide (D). It is preferable that When the addition amount of the polycarbonate polyol (B2) is 40% by mass or more, the weather resistance of the resulting urethane resin is good and the adhesion to the plastic sheet is also good. Moreover, the cohesive force of the obtained cationic polyurethane is enough as it is 80 mass% or less, and it is excellent also in water resistance.

  A polyalkylene oxide (D) containing 50% by mass or more of an ethylene oxide chain is used as a constituent component of the polyurethane, and this polyalkylene oxide (D) can enhance the absorbability of the ink. Examples of such polyalkylene oxide (D) include ethylene oxide, a copolymer of ethylene oxide and propylene oxide, and the like. These polyalkylene oxides (D) can be used individually by 1 type or in mixture of 2 or more types. The ethylene oxide chain in the polyalkylene oxide (D) needs to be 50% by mass or more as described above. By setting the ethylene oxide chain to 50% by mass or more, the ability to absorb ink can be enhanced.

  The addition amount of polyalkylene oxide (D) is 3-10 mass% with respect to the total amount of polyisocyanate (A), polycarbonate polyol (B2), chain extender (C), and polyalkylene oxide (D). Preferably there is. When the addition amount of the polyalkylene oxide (D) is 3% by mass or more, good ink absorbability can be obtained, and when it is 10% by mass, the water resistance can be improved.

The chain extender (C) used in the preparation (2) is the same as in the preparation (1).
The addition amount of the chain extender (C) used in the preparation (2) is based on the total amount of the polyisocyanate (A), the polycarbonate polyol (B2), the chain extender (C), and the polyalkylene oxide (D). 5 to 15% by mass is preferable. The amount of the chain extender (C) added is 5% by mass or more, so that a tertiary amino group can be sufficiently introduced and adhesion can be obtained. The effect of improving the property is obtained.

  Acid and quaternizing agent when the tertiary amino group introduced by the chain extender (C) used in the preparation (2) and a part thereof are neutralized with an acid or quaternized with a quaternizing agent Is the same as in the case of the preparation (1).

  In the preparation of the above (1) and (2), the cationic urethane prepolymer obtained by neutralizing or quaternizing the tertiary amino group and a part of the tertiary amino group is added to the polyamine compound (D1) as needed when dispersed in water. ) May be used. Examples of the polyamine compound (D1) that can be used include hydrazides such as ethylenediamine, propylenediamine, diethylenetriamine, hexylenediamine, triethylenetetramine, tetraethylenepentamine, isophoronediamine, piperazine, diphenylmethanediamine, hydrazine, and adipic acid dihydrazide. Examples thereof include compounds having two or more amino groups.

  In the preparation of the above (1) and (2), a polyol having 3 or more hydroxyl groups may be further added. When a polyol having 3 or more hydroxyl groups is added, adhesion to a plastic sheet can be improved. However, it is necessary to use the obtained cationic polyurethane as long as the water dispersibility is not impaired. Examples of such polyols include sorbitol, 1,2,3,6-hexanetetraol, 1,4-sorbitan, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerin, trimethylol. Ethane, trimethylolpropane, pentaerythritol and the like can be mentioned, and these can be used alone or in combination of two or more.

In the preparation of (1) and (2) above, the cationic urethane prepolymer obtained by neutralizing or quaternizing the tertiary amino group or a part thereof is then dispersed in water and used in the present invention. It is obtained as a cationic polyurethane and its dispersion.
The cationic polyurethane can be used in the form of a dispersion.

  Further, the cationic polyurethane may be in a form further containing an inorganic water absorbing material. Inorganic water-absorbing materials include light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium oxide, zinc oxide, zinc sulfate, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, none Examples thereof include regular silica, aluminum hydroxide, alumina, ritbon, etc. Amorphous silica is preferable from the viewpoint of printing speed and color developability.

  The use of cationic polyurethane is also effective in that it can be satisfactorily applied to plastic sheets such as soft polyvinyl chloride, semi-rigid polyvinyl chloride, hard polyvinyl chloride, polyethylene terephthalate (PET), polypropylene, and polyethylene.

  Specifically, the resins described in paragraph numbers 0006 to 0048 of JP-A No. 2002-307811 and paragraph numbers 0006 to 0053 of JP-A No. 2002-307812 can be used as the cationic polyurethane.

  The content of the cationic polymer (preferably cationic polyurethane) in the ink receiving layer is preferably 0.1 to 10% by mass, more preferably 0.3 to 5% by mass with respect to pseudoboehmite-like alumina hydrate. %, Particularly preferably 0.5 to 3% by mass.

-Water-soluble manganese compounds-
The ink receiving layer in the invention contains at least one water-soluble manganese compound. By containing the water-soluble manganese compound, the light resistance and ozone resistance of the recorded image can be improved.

  Examples of the water-soluble manganese compound include manganese sulfate, manganese nitrate, manganese chloride, manganese acetate, manganese benzoate and the like, and are not particularly limited as long as they are divalent manganese compounds.

  The content of the water-soluble manganese compound in the ink-receiving layer is preferably 0.2 to 2.0 parts by mass, more preferably 0.2 to 1 with respect to 100 parts by mass of the pseudoboehmite-like alumina hydrate. 0.0 part by mass. When the content of the water-soluble manganese compound is within the above range, the light resistance and ozone resistance are more effective while avoiding photo-oxidation of the manganese compound itself and browning of the non-printed part (white part) due to oxidizing gas. Can be improved.

-Ammonium sulfate-
The ink receiving layer in the invention contains at least one ammonium sulfate. In the presence of ammonium sulfate, failure of the non-printing part (white part) that occurs when the water-soluble manganese compound is used to improve light resistance and ozone resistance, that is, due to photooxidation of the manganese compound itself or an oxidizing gas The browning of the non-printing part (white part) can be prevented.

  Ammonium sulfate is not particularly limited, and those commonly used in reagents and the like can be used.

  The content of ammonium sulfate in the ink receiving layer is preferably 50 to 500 parts by mass, more preferably 150 to 300 parts by mass with respect to 100 parts by mass of the water-soluble manganese compound. By setting the ammonium sulfate content to 50 parts by mass or more, the photo-oxidation of the manganese compound itself and the browning of the non-printing part (white part) due to the oxidizing gas can be effectively suppressed, and by setting it to 500 parts by mass or less. The light resistance and ozone resistance of the image are not lowered by the addition of the water-soluble manganese compound.

When the specific surface area of the ink receiving layer is adjusted to 100 to 300 m ² / g in consideration of the glossiness of the ink receiving layer and the decrease in density of the black (Bk) image due to the white haze of the image, Since the browning due to photo-oxidation of the manganese compound itself may become more prominent, in such a case, it is one of preferred modes to add glycerin together with ammonium sulfate into the ink receiving layer.

The glycerin is not particularly limited, and may be a general one that is usually used as a reagent. When glycerin is added, the amount of glycerin added in the ink receiving layer is preferably 0.2 to 3.0 parts by weight, more preferably 0.3 parts per 100 parts by weight of the pseudoboehmite-like alumina hydrate. -1.0 mass part. When the specific surface area of the ink receiving layer is adjusted to 100 to 300 m ² / g by setting the addition amount of glycerin to 0.2 parts by mass or more, browning due to photooxidation of the manganese compound itself is effectively suppressed, When the content is 3.0 parts by mass or less, good ink absorptivity can be obtained, and bleeding and beading can be prevented.

  The method for adding the water-soluble manganese compound, ammonium sulfate, and glycerin to the ink receiving layer in the present invention is not particularly limited. For example, (i) a direct addition to a liquid containing pseudoboehmite-like alumina hydrate and PVA is applied. And a method of forming an ink receiving layer by applying the solution and (ii) after forming the ink receiving layer, an aqueous solution containing a water-soluble manganese compound, ammonium sulfate and glycerin is applied onto the ink receiving layer and absorbed. (Iii) A method of finishing a glossy surface by using an aqueous solution containing a water-soluble manganese compound, ammonium sulfate, and glycerin as a casting solution in the rewet method.

-Colloidal silica-
The uppermost layer constituting the ink receiving layer in the invention preferably contains at least one colloidal silica. By including colloidal silica, the glossiness of the ink receiving layer surface is further improved, and a smooth hand-feel is obtained.

  The uppermost layer can be configured as a layer mainly containing colloidal silica. Containing mainly colloidal silica means that the content of colloidal silica is 70% by mass or more based on the total solid content (mass) of the layer. Preferably, the amount of colloidal silica mainly contained is 80% by mass or more, more preferably 90% by mass or more.

In particular, by adjusting the solid coating amount of colloidal silica to such an amount that a thin film of 0.3 g / m ² or less can be obtained, high glossiness and good touch feeling can be obtained while maintaining high ink absorption, and pigment ink This can improve the darkness (loss of gloss) in high density areas when recorded with. The lower limit of the solid content coating amount of colloidal silica is 0.05 g / m ² . When the solid content coating amount of colloidal silica is 0.05 g / m ² or more, it is possible to ensure high gloss and good touch feeling. The solid content coating amount of colloidal silica is more preferably 0.1 to 0.25 g / m ² .

  Colloidal silica is a colloidal dispersion of silicon dioxide obtained by heating and aging a silica sol obtained through metathesis with an acid of sodium silicate or the like through an ion exchange resin layer. The colloidal silica preferably has an average primary particle size of 20 to 80 nm, more preferably 20 to 60 nm, from the viewpoint of glossiness of the white paper portion and ink absorbability.

  As commercial products of colloidal silica, PL-10A, PL-3L, PL-1 manufactured by Fuso Chemical Co., Ltd., Snowtex ST-20, ST-30, ST-40 manufactured by Nissan Chemical Industries, Ltd., ST-C, ST-N, ST-20L, ST-O, ST-OL, ST-S, ST-XS, ST-XL, ST-YL, ST-ZL, ST-OZL, ST-UP, ST- OUP, ST-PS-MO, etc. can be used.

  In addition, the uppermost layer can contain a hydrophilic binder, a surfactant, a pH adjuster and the like. About a hydrophilic binder, it is preferable that the content is 5 mass% or less with respect to colloidal silica from an ink absorptive viewpoint, More preferably, it is not adding.

-Other ingredients than the above-
Hereinafter, in addition to the above, components that can be contained in the ink receiving layer will be described in detail.
(Inorganic fine particles)
The ink receiving layer in the present invention may contain inorganic fine particles other than pseudoboehmite-like alumina hydrate as long as the effects of the present invention are not impaired.
Further, in the present invention, in addition to the ink receiving layer in the present invention containing pseudo boehmite-like alumina hydrate, ink receiving containing other inorganic fine particles with or without pseudo boehmite-like alumina hydrate. A layer may be provided.

  The kind of the inorganic fine particles is not particularly limited, but a porous layer can be formed, and vapor phase silica, alumina, or alumina hydrate is preferable in terms of gloss and ink absorbability. The inorganic fine particles may be used alone or in combination.

The gas phase method silica is also called a dry method as opposed to a wet method, and is generally made by a flame hydrolysis method. Specifically, a method of making silicon tetrachloride by burning with hydrogen and oxygen is generally known, but silanes such as methyltrichlorosilane and trichlorosilane can be used alone or tetrachlorosilane instead of silicon tetrachloride. It can be used in a mixed state with silicon.
Gas phase method silica is commercially available in the Aerosil series manufactured by Nippon Aerosil Co., Ltd., the QS type manufactured by Tokuyama Co., Ltd., etc., and can be easily obtained. The average primary particle diameter of the vapor phase method silica is preferably 5 to 50 nm, and in order to obtain higher gloss, it is preferably 5 to 20 nm and a specific surface area by the BET method of 90 to 400 m ² / g. The BET method is one of the methods for measuring the surface area of a powder by a vapor phase adsorption method, and is a method for obtaining the total surface area, that is, the specific surface area of a 1 g sample from an adsorption isotherm. Generally, nitrogen gas is often used as the adsorbed gas, and the most frequently used method is to measure the amount of adsorption from the change in pressure or volume of the gas to be adsorbed. The most prominent one representing the isotherm of multimolecular adsorption is the Brunauer Emmett Teller equation (BET equation), which is widely used for determining the surface area. The adsorption amount is obtained based on the BET equation, and the surface area is obtained by multiplying the area occupied by one adsorbed molecule on the surface.

  As the alumina, γ-alumina, which is a γ-type crystal of aluminum oxide, is preferable, and among them, a δ group crystal is preferable. Although γ-alumina can reduce the primary particles to about 10 nm, usually, secondary particles of several thousand to several tens of thousands of nm are converted to 50 to 50 with an ultrasonic wave, a high-pressure homogenizer, a counter collision type jet pulverizer, or the like. What grind | pulverized to about 300 nm is used preferably.

(Cationic compound)
The ink receiving layer in the invention may contain a cationic compound other than the cationic polymer containing quaternary ammonium as described above in the skeleton. For example, when vapor phase silica is contained as the inorganic fine particles, the use of a cationic compound can prevent cracking of the ink receiving layer and improve water resistance.

  As the cationic compound, a cationic polymer other than the cationic polymer containing quaternary ammonium in the skeleton or a water-soluble polyvalent metal compound is preferably used. These cationic compounds and water-soluble polyvalent metal compounds can be used singly or in combination of two or more.

  Examples of the cationic polymer include water-soluble cationic polymers having a phosphonium group and a primary to tertiary amine acid adduct. For example, polyethylenimine, polyallylamine, allylamine epichlorohydrin polycondensate, JP-A-59-20696, 59-33176, 59-33177, 59-155888, 60-11389, 60- 49990, 60-83882, 60-109894, 62-198493, 63-49478, 63-115780, 63-280681, JP-A-1-40371, 6-234268 No. 7, 7-125411, and 10-1937776.

The weight average molecular weight of the cationic polymer is preferably 100,000 or less, more preferably 50,000 or less, and the lower limit is about 2,000.
Moreover, the usage-amount of a cationic polymer has the preferable range of 1-10 mass% with respect to a gaseous-phase method silica.

Examples of the polyvalent metal in the water-soluble polyvalent metal compound include calcium, barium, manganese, copper, cobalt, nickel, aluminum, iron, zinc, zirconium, titanium, chromium, magnesium, tungsten, and molybdenum. It can be used as a water-soluble salt of these metals. Specific examples of water-soluble polyvalent metal compounds include calcium acetate, calcium chloride, calcium formate, calcium sulfate, barium acetate, barium sulfate, barium phosphate, manganese chloride, manganese acetate, manganese formate dihydrate, manganese sulfate Ammonium hexahydrate, cupric chloride, ammonium copper (II) chloride dihydrate, copper sulfate, cobalt chloride, cobalt thiocyanate, cobalt sulfate, nickel sulfate hexahydrate, nickel chloride hexahydrate, acetic acid Nickel tetrahydrate, nickel ammonium sulfate hexahydrate, amido nickel sulfate tetrahydrate, aluminum sulfate, aluminum sulfite, aluminum thiosulfate, polyaluminum chloride, aluminum nitrate nonahydrate, aluminum chloride hexahydrate, Ferrous bromide, ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, zinc bromide Zinc chloride, zinc nitrate hexahydrate, zinc sulfate, zirconium acetate, zirconium nitrate, basic zirconium carbonate, zirconium hydroxide, zirconium carbonate / ammonium, zirconium carbonate / potassium, zirconium sulfate, zirconium fluoride, zirconium chloride, zirconium chloride Octahydrate, zirconium oxychloride, hydroxyzirconium chloride, titanium chloride, titanium sulfate, chromium acetate, chromium sulfate, magnesium sulfate, magnesium chloride hexahydrate, magnesium citrate nonahydrate, sodium phosphotungstate, citric acid Examples thereof include sodium tungsten, 12 tungstophosphoric acid n hydrate, 12 tungstosilicic acid 26 hydrate, molybdenum chloride, 12 molybdophosphoric acid n hydrate, and the like. Among these, aluminum or a water-soluble salt of a periodic table group IVa element (zirconium, titanium) is preferable.
Here, “water-soluble” means that 1% by mass or more dissolves in water at room temperature and normal pressure.

As a water-soluble aluminum compound other than the above, a basic polyaluminum hydroxide compound is preferably used. The main component of this compound is represented by the following formula 1, formula 2 or formula 3, and, for example, [Al ₆ (OH) ₁₅ ] ³⁺ , [Al ₈ (OH) ₂₀ ] ⁴⁺ , [Al ₁₃ (OH) ₃₄ ] ⁵⁺ and [Al ₂₁ (OH) ₆₀ ] ^{3+ and the} like are water-soluble polyaluminum hydroxides stably containing a basic and high-molecular polynuclear condensed ion.

[Al ₂ (OH) _n Cl _6-n ] _m Formula 1
[Al (OH) ₃ ] _n AlCl ₃ Formula 2
Al _n (OH) _m Cl _{(3 nm)} [0 <m <3n] Formula 3

  These are water treatment agents under the name of polyaluminum chloride (PAC) from Taki Chemical Co., Ltd., under the name of polyaluminum hydroxide (Paho) from Asada Chemical Co., Ltd., and Purachem from Riken Green Co., Ltd. It is commercially available under the name of WT and from other manufacturers for the same purpose, and various grades can be easily obtained. In the present invention, these commercially available products may be used as they are. These basic polyaluminum hydroxide compounds are also described in Japanese Patent Publication Nos. 3-24907 and 3-42591.

When the water-soluble polyvalent metal compound is contained, the content in the ink receiving layer is preferably 0.1 to 10 g / m ² , more preferably 0.2 to 5 g / m ² .

(Surfactant)
The ink receiving layer in the present invention can be constituted using a surfactant. When the surfactant is contained, application failure such as application stripes on the coating film formed by application can be suppressed.
The surfactant is preferably a nonionic one. In addition to nonionic properties, any type of anionic, cationic, nonionic, and betaine types can be selected and used as required. Moreover, a low molecular thing or a high molecular thing may be used, and it may be used individually by 1 type or in combination of 2 or more types.
The content of the surfactant in the ink receiving layer is preferably 0.001 to 5 parts by mass, more preferably 0.01 to 3 parts by mass with respect to 100 parts by mass of pseudoboehmite-like alumina hydrate.

(Oil drop)
Various oil droplets can be contained for the purpose of improving the brittleness of the ink receiving layer. As oil droplets, hydrophobic high boiling point organic solvents (for example, liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicon oil, etc.) having a solubility in water at room temperature of 0.01% by mass or less, and polymer particles (for example, , Particles obtained by polymerizing one or more polymerizable monomers such as styrene, butyl acrylate, divinylbenzene, butyl methacrylate, and hydroxyethyl methacrylate). The amount of oil droplets used is preferably in the range of 10 to 50% by mass relative to the hydrophilic binder.

  In addition to the above, the ink-receptive layer in the present invention includes colored dyes, colored pigments, ink dye fixing agents, ultraviolet absorbers, antioxidants, pigment dispersants, antifoaming agents, leveling agents, preservatives, fluorescent enhancers. Various known additives such as a whitening agent, a viscosity stabilizer, and a pH adjuster can also be added.

  The coating liquid for forming the ink receiving layer (ink receiving layer coating liquid) preferably has a pH in the range of 3.3 to 6.0, particularly preferably in the range of 3.5 to 5.5. By combining the pH of this ink-receiving layer coating solution with the pH of the coating solution for forming the uppermost layer when the uppermost layer contains colloidal silica (= 3.3 to 6), better ink absorbability , Glossy and uniform coated surface.

  Further, in order to improve the resolution of the image, if it does not cause aggregation or the like when mixed with a dispersion of alumina hydrate, the ink receiving layer may be a fluororesin, silicone resin, or alkylketene. By containing a dimer-based water repellent or sizing agent, the resolution of the image can be improved by controlling the print dot diameter. As these water repellents or sizing agents, commercially available ones can be used. In addition, either a solution or an aqueous emulsion can be used. The print dot diameter can be controlled by the amount added to the ink receiving layer. The amount added varies depending on each component and concentration and the desired print dot diameter, but as an effective solid component, it is usually 0.05 to 10% by mass, preferably 0.1%, based on the total solid content of the ink receiving layer. ˜5 mass%.

  The inkjet recording medium of the present invention is prepared by forming pseudoboehmite-like alumina hydrate, polyvinyl alcohol having a saponification degree of less than 90% and a polymerization degree of 3000 or more, a crosslinking agent for crosslinking the polyvinyl alcohol, and a quaternary ammonium skeleton. Can be suitably prepared by a method in which an ink-receiving layer is formed by applying a prepared solution prepared by mixing a cationic latex, a water-soluble manganese compound, and ammonium sulfate onto a water-resistant support. In particular, since alumina hydrate exists in the liquid in a bare state, non-particulate cationic polymers tend to adsorb on the surface of the alumina hydrate and tend to cause aggregation of the coating solution, but have a hydrophobic property. By using a cationic latex, aggregation with alumina hydrate can be suppressed, and an image with high density and suppressed bleeding can be obtained. Furthermore, light resistance and ozone resistance are also good due to the presence of the water-soluble manganese compound and ammonium sulfate.

  The ink jet recording medium of the present invention preferably comprises a step of preparing an alumina dispersion in which pseudoboehmite-like alumina hydrate is dispersed in an aqueous solvent (hereinafter sometimes referred to as “dispersion preparation step”). A step of preparing a coating solution by mixing an alumina dispersion, an aqueous solution containing polyvinyl alcohol, a crosslinking agent, a cationic latex, a water-soluble manganese compound, and ammonium sulfate (hereinafter sometimes referred to as “coating solution preparation step”); The prepared coating liquid is applied to a water-resistant support to form an ink receiving layer (hereinafter, also referred to as “layer forming step”).

  In the dispersion preparation step, an alumina dispersion in which pseudo boehmite-like alumina hydrate is dispersed in an aqueous solvent is prepared. The preparation of the alumina dispersion is preferably obtained by mixing pseudoboehmite-like alumina hydrate with an aqueous solvent (for example, ion-exchanged water) and dispersing with a high-pressure disperser. More preferably, first, pseudoboehmite-like alumina hydrate is mixed with water (for example, ion-exchanged water), stirred with a stirrer to prepare a coarse dispersion, and this is further finely dispersed with a high-pressure disperser. A dispersion is obtained. By using a high-pressure disperser to disperse pseudoboehmite-like alumina hydrate, it becomes more finely divided, so even after the ink solvent penetrates (that is, after recording), the haze is kept low to maintain transparency and high concentration. A glossy photo-like image can be obtained.

  In the present invention, an alumina dispersion may be prepared, or a commercially available alumina dispersion prepared in advance may be obtained and used.

  Examples of the stirrer include a dissolver and a suction disperser. As stirring conditions, the temperature is preferably 10 to 50 ° C., and the stirring time is preferably 1 to 30 minutes from the viewpoint of viscosity.

  As the high-pressure disperser, for example, a high-pressure homogenizer such as an optimizer (for example, HJP25005 manufactured by Sugino Machine Co., Ltd.) that makes pressurized slurry-like raw materials collide with each other at an ultra high speed and a cavitation is used. Can be used.

  The dispersed particle size after fine dispersion is preferably 0.10 to 0.14 μm, more preferably 0.10 to 0.12 μm in terms of the particle size immediately after fine dispersion, from the viewpoint of printing density.

  The concentration of the pseudo boehmite-like alumina hydrate in the (A) alumina dispersion can be selected according to the desired amount required for the coating solution prepared in the subsequent step, but from the viewpoint of the coating solution viscosity, the total mass 20-40 mass% is preferable with respect to.

  Examples of the aqueous solvent include water such as pure and ion-exchanged water and a mixed solvent of water and an organic solvent soluble in the water. As the organic solvent soluble in water, for example, methanol, ethanol, propanol, butanol and the like can be selected according to the purpose.

  The coating liquid preparation step includes an alumina dispersion obtained in the dispersion preparation step, an aqueous solution containing polyvinyl alcohol having a saponification degree of less than 90% and an average polymerization degree of 3000 or more, a crosslinking agent that crosslinks at least polyvinyl alcohol, and quaternary ammonium. Is mixed with cation latex containing water in a skeleton, a water-soluble manganese compound, and ammonium sulfate to prepare a coating solution.

  It is desirable to prepare a coating solution by mixing while keeping the temperature at 50 ° C. or higher. By performing the mixing while keeping the temperature at 50 ° C. or higher, secondary aggregation can be suppressed, so that an increase in the viscosity of the liquid can be prevented. For example, when pseudoboehmite-like alumina hydrate and PVA are mixed, the viscosity tends to increase with time or thixotropy tends to appear. By controlling the temperature of the coating solution within the above range, it is possible to avoid a change with time in the viscosity of the coating solution. Thereby, the coating stability is improved, and the film quality of the coating film surface can be kept good.

There is no restriction | limiting in particular in a mixing method, The method of mixing in arbitrary orders and stirring using a dissolver, a suction disperser, etc. are mentioned, for example. The stirring temperature is desirably kept at 50 ° C. or more in view of preventing thickening, and is preferably kept at 55 to 65 ° C.
Further, from the viewpoint of obtaining a higher printing density by obtaining a higher density and lowering the glossiness and haze after ink penetration into the solvent (after recording), it is preferable to mix the crosslinking agent by in-line mixing. For example, an aqueous crosslinking agent solution may be mixed in-line with a mixed solution of an alumina dispersion and a PVA aqueous solution.

An aqueous solution containing PVA (PVA aqueous solution) can be prepared by dissolving the aforementioned PVA and, if necessary, one or more other water-soluble binders in an aqueous solvent. As an aqueous solvent, the thing similar to the aqueous solvent which can be used at the above-mentioned dispersion liquid preparation process can be used.
The density | concentration in PVA aqueous solution of PVA can be selected according to the desired quantity required for a coating liquid. For the preparation of the coating solution, the aqueous PVA solution can be used so that the amount of the water-soluble binder contained in the coating solution is within the above range.

The crosslinking agent can be used as an aqueous crosslinking agent solution. The aqueous crosslinking agent solution can be prepared by dissolving one or more crosslinking agents (preferably boric acid and / or a salt thereof) in an aqueous solvent. As an aqueous solvent, the thing similar to the aqueous solvent which can be used at the above-mentioned dispersion liquid preparation process can be used.
The concentration of the crosslinking agent in the aqueous crosslinking agent solution can be selected according to the desired amount required for the coating solution. For the preparation of the coating solution, the aqueous crosslinking agent solution can be used so that the amount of the crosslinking agent contained in the coating solution is within the above range.

  In the present invention, the cationic polymer in the ink receiving layer is preferably contained using a cationic latex containing quaternary ammonium as a skeleton. Among them, it is preferable to use a composition in which cationic polyurethane is dispersed in water, that is, an aqueous dispersion, and the compositions and aqueous dispersions obtained by the preparations (1) and (2) described above are particularly preferable.

  In addition, the water-soluble manganese compound and ammonium sulfate may be added directly to the previously prepared alumina dispersion, PVA aqueous solution, cross-linking agent aqueous solution, cationic latex, or a mixture of at least two of these, and each used as an aqueous solution. Also good.

In the layer forming step, the ink receiving layer is formed by applying the coating solution prepared in the coating solution preparing step onto a water-resistant support. The coating is preferably performed while keeping the coating solution at a temperature of 35 to 70 ° C. When the temperature of the coating solution is 35 ° C. or higher, the gelation of the coating solution can be suppressed, and the coating can be performed satisfactorily. Can be obtained.
Furthermore, by setting the temperature of the coating solution at the time of coating to 50 ° C. or higher, the coating solution is more difficult to thicken with time, and a uniform coated surface can be obtained. For the same reason, the coating solution temperature is preferably 50 to 70 ° C, more preferably 50 to 60 ° C.

  Application | coating can be performed using a coating apparatus. As a coating method, for example, a known coating method such as a slide hopper method, a curtain method, an extrusion method, an air knife method, a roll coating method, or a rod bar coating method is used.

The coating amount of the coating liquid for the ink receiving layer is preferably 3 to 50 g / ^{m 2} in terms of solid content, more preferably 20~45g / ^{m 2.} When the coating amount is within the above range, the drying property of the coating film is good, and the occurrence of cracks can be avoided.

  After application, it is usually dried. Although drying temperature is based also on the heat resistance of a water-resistant support body, 60-200 degreeC is preferable, More preferably, it is 70-150 degreeC. When the drying temperature is within the above range, the ink receiving layer can be sufficiently dried to improve the ink absorbency when heat-treated within a range that does not adversely affect the support, and the ink receiving layer has water resistance. It can be improved. The temperature of the heat treatment here depends on the heat resistance of the water-resistant support, but is preferably 100 to 200 ° C, more preferably 120 to 150 ° C.

  Drying is preferably performed under conditions including the case where the film surface temperature of the coating film is less than 30 ° C. In the drying process, it is only necessary to include a drying step in which the film surface temperature is less than 30 ° C. Specifically, the film surface temperature may be 30 ° C. or lower in the initial stage of drying, or the film surface temperature is decreased to 30 ° C. or lower after a predetermined time has elapsed from the start of drying or in the latter stage of drying. It may be. Among these, from the viewpoint of uniform coated surface shape and void volume, it is preferable to carry out the drying step in which the film surface temperature is less than 30 ° C. at the initial stage of drying, particularly immediately after the start of drying. By performing drying so that the film surface temperature is less than 30 ° C. at the initial stage of drying (particularly immediately after the start of drying), uneven drying can be avoided even when the coating solution has a low viscosity, and glossiness can be enhanced.

  As minimum film surface temperature, 0-30 degreeC is preferable and 5-20 degreeC is still more preferable. By setting the film surface temperature to 0 ° C. or higher, it is possible to suppress the excessive increase in the viscosity of the coating liquid, prevent the formation of unevenness on the surface of the coating film, and obtain a glossy feeling. The film surface temperature is the temperature of the coating film surface during drying, and can be measured with a radiation thermometer.

  In addition to the above, coating conditions (coating apparatus, coating liquid temperature, viscosity, etc.) and drying conditions (drying temperature, drying time, temperature gradient, air volume, how to apply wind, humidity) of the ink receiving layer coating liquid Etc.) can be selected as appropriate to control the physical properties of the ink receiving layer to be formed.

The preparation of the coating liquid (ink receiving layer coating liquid) for forming the ink receiving layer constituting the ink jet recording medium of the present invention can be performed, for example, as follows.
First, pseudoboehmite-like alumina hydrate is added to water (for example, ion-exchanged water), stirred with a stirrer such as a dissolver to prepare a coarse dispersion, and further finely dispersed with a high-pressure disperser. An alumina-containing dispersion is obtained. Subsequently, the alumina-containing dispersion is made of polyvinyl alcohol, boric acid and / or a salt thereof (crosslinking agent), a cationic polyurethane aqueous dispersion (cationic latex), a water-soluble manganese compound, and ammonium sulfate. Stir and mix with other ingredients accordingly. At this time, each component (for example, each aqueous solution containing each component) is adjusted to a desired temperature (preferably 50 ° C. or higher) before mixing, and each component (for example, each aqueous solution) is adjusted to a desired temperature (preferably 50 ° C.). It is preferable to perform mixing while keeping the temperature as above.

  From the viewpoint of further improving the coating property of the coating liquid, or from the viewpoint of adjusting the dot diameter when the ink adheres to the ink receiving layer, a surfactant is added to the coating liquid for forming the ink receiving layer. It is preferable. The details of the surfactant are as described above.

-Water resistant support-
The water-resistant support constituting the ink jet recording medium of the present invention is preferably a resin-coated paper provided with a resin coating layer on both sides of the base paper.
The pulp used for the base paper constituting the resin-coated paper is, for example, virgin pulp such as chemical pulp such as LBKP, NBKP, LBSP, NBSP, LUKP, NUKP, LUSP, NUSP, mechanical pulp such as GP, TMP, newspaper Recycled pulp from waste paper, magazines, office waste paper, etc. can be used.

  The base paper is filled with a white pigment having an average particle size of 0.3 to 10 μm as a filler, for example, at least one of calcium carbonate, magnesium carbonate, talc, kaolin, silica, alumina, titanium dioxide, barium sulfate, etc. It is used in an amount of 2 to 30% by mass, preferably 4 to 30% by mass, based on the minute. White pigments having an average particle size of less than 0.3 μm have poor yield on paper during papermaking, and white pigments having a mean particle size of more than 10 μm have poor paper texture. In particular, a white pigment having a whiteness degree defined by JIS-M8016 of 88% or more is preferably used. When the white pigment is less than 2% by mass of the base paper, it is difficult to obtain a sufficiently white base paper. When the white pigment is more than 30% by mass, problems such as dirt and a reduction in the strength of the base paper occur in the production process. The base paper is mixed with additives such as various sizing agents, paper strength enhancers, antistatic agents, fluorescent whitening agents, and dyes that are generally used in papermaking.

  Furthermore, the surface of the base paper may be coated with a surface sizing agent, surface paper strength agent, fluorescent brightening agent, antistatic agent, dye, anchor agent or the like.

  The thickness of the base paper is preferably 70 to 200 μm. The thickness is adjusted by applying pressure on the paper during paper making or after paper making and compressing it. Those having good surface smoothness are preferred, but if they are compressed too much, the whiteness tends to decrease.

As the resin, a low density polyethylene having a density of 0.91~0.93g / cm ^3, high density polyethylene having a density of 0.94~0.96g / cm ^3, medium density polyethylene of medium density, polypropylene, polybutene, polypentene A copolymer of two or more olefins such as an olefin homopolymer or an ethylene-propylene copolymer and a mixture thereof, such as polyolefin resin, polyvinyl chloride, polyvinylidene chloride, polymethyl methacrylate, polystyrene, etc. Those having various densities and melt viscosity indices (melt index) can be used alone or as a mixture thereof. In particular, a polyolefin resin is preferably used from the viewpoint of handleability, and it is particularly preferable to contain 50% by mass or more of low density polyethylene having a density of 0.91 to 0.93 g / cm ³ in the total resin solid content of the resin coating layer.

  Further, in the resin coating layer on the side where the ink receiving layer is provided on at least the resin-coated paper, white particles such as titanium dioxide, barium sulfate, zinc oxide, calcium carbonate, magnesium carbonate having an average particle diameter of 0.1 to 1 μm. At least one pigment can be contained in an amount of 5 to 20% by mass, preferably 7 to 15% by mass, based on the solid content of the total resin. A white pigment having an average particle size of less than 0.1 μm has a low concealing effect. In particular, a white pigment having a whiteness degree defined by JIS-M8016 of 88% or more is preferably used. By setting the white pigment to 5% by mass or more based on the solid content of the resin, sufficient opacity of the resin-coated paper can be obtained even when the thickness of the base paper is thin. Moreover, by setting it as 20 mass% or less, the nonuniformity by the generation | occurrence | production of a crack etc. on the surface of a resin layer is suppressed, and intensity | strength can be maintained. Other additives include fatty acid amides such as stearic acid amide and arachidic acid amide, fatty acid metal salts such as zinc stearate, calcium stearate, aluminum stearate and magnesium stearate, antioxidants such as Irganox 1010 and Irganox 1076, Various additives such as blue pigments and dyes such as cobalt blue, ultramarine blue, cecilian blue, and phthalocyanine blue, magenta pigments and dyes such as cobalt violet, fast violet, and manganese purple, fluorescent whitening agents, and UV absorbers are appropriately used. Add in combination.

  The main production method of the resin-coated paper is produced by a so-called extrusion coating method in which a thermoplastic resin is cast on a traveling base paper in a heated and melted state, and the base paper is coated with the resin. Further, before the resin is coated on the base paper, the base paper is preferably subjected to an activation treatment such as corona discharge treatment or flame treatment. The resin coating layer on the back surface is usually a matte surface, and an active treatment such as a corona discharge treatment or a flame treatment can be applied to the front surface or both the front and back surfaces as necessary.

  The front side resin layer on which the ink receiving layer of the resin-coated paper is formed is obtained by mainly heating and melting a thermoplastic resin on one side of the base paper with an extruder, extruding it into a film between the base paper and a cooling roll, pressing and cooling. Manufactured. At this time, the cooling roll is used to form the surface shape of the resin coating layer, and the surface of the resin layer is molded into a mirror surface, a fine rough surface, or a patterned silk or mat shape depending on the shape of the cooling roll surface. can do.

  The back side resin layer opposite to the front side resin layer of the resin-coated paper can also be produced by heating and melting the resin with an extruder, extruding it into a film between the base paper and a cooling roll, pressing and cooling. At this time, preferably, from the viewpoint of transportability in the printer, the cooling roll is preferably a finely roughened surface or patterned depending on the shape of the cooling roll surface so that Ra specified in JIS-B-0601 is 0.8 to 5 μm. For example, it is preferable to mold the material into a silky shape or a mat shape.

  The method of providing the resin coating layer on the base paper includes the method of irradiating the electron beam after applying the electron beam curable resin, in addition to extruding the heated molten resin, and drying after applying the coating solution of the polyolefin resin emulsion. And a method of performing a surface smoothing treatment. In any case, a resin-coated paper applicable to the present invention can be obtained by performing molding with a hot roll having irregularities.

An undercoat layer may be provided on the front side surface of the resin-coated paper in order to improve adhesion. The undercoat layer is applied and dried in advance on the surface of the resin layer of the support before the ink receiving layer is applied. The undercoat layer is a layer mainly comprising a water-soluble polymer capable of forming a film, a polymer latex or the like, and preferably a water-soluble polymer such as gelatin, polyvinyl alcohol, polyvinyl pyrrolidone, or water-soluble cellulose is used. Preferably it is formed using gelatin. 10-500 mg / m < ² > is preferable and, as for the adhesion amount of a water-soluble polymer, 20-300 mg / m < ² > is more preferable. The undercoat layer preferably further contains a surfactant or a hardener. Moreover, it is preferable to perform a corona discharge treatment before forming the undercoat layer (by coating or the like) on the resin-coated paper.

  Appropriate selection of application conditions (coating equipment, coating liquid temperature, viscosity, etc.) and drying conditions (drying temperature, drying time, temperature gradient, air volume, air flow, humidity, etc.) when forming the ink receiving layer By doing so, the physical properties of the ink receiving layer can be controlled.

The drying temperature of the coating film formed by coating depends on the heat resistance of the support, but is preferably in the range of 60 to 200 ° C, more preferably 70 to 150 ° C.
In addition, after the application, after the ink receiving layer is sufficiently dried, the pore volume of the ink receiving layer can be increased by performing a heat treatment within a range that does not adversely affect the support, so that the ink absorbability is improved. Furthermore, the water resistance of the ink receiving layer can be improved. The temperature for the heat treatment depends on the heat resistance of the support, but is preferably from 100 to 200 ° C, more preferably from 120 to 150 ° C.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof. Unless otherwise specified, “part” is based on mass. Further, in this example, an example of producing an ink jet recording sheet as an example of the ink jet recording medium is mainly shown.

Example 1
-Preparation of alumina white transparent dispersion-
While stirring 2042 g of ion-exchanged water with a dissolver, 708 g of Cataloid AP-5 (manufactured by Catalytic Chemical Industry Co., Ltd .; pseudoboehmite-like alumina hydrate) was added to obtain a white coarse dispersion of alumina. The number of revolutions of the dissolver at this time was 3000 rpm, and the rotation time was 10 minutes.

  Subsequently, the alumina coarse dispersion is finely dispersed with a high-pressure disperser (Ultimizer HJP25005, manufactured by Sugino Machine Co., Ltd.) to obtain a white transparent alumina dispersion (alumina white transparent dispersion) having a solid content concentration of 25%. It was. The pressure at this time was 100 MPa, and the discharge rate was 600 g / min.

  About the obtained alumina white transparent dispersion, the liquid temperature was adjusted to 30 ° C., and diluted with ion-exchanged water so that the transmittance measured with LA-920 (manufactured by Horiba, Ltd.) was 80%. The particle diameter of the dispersed particles was measured with LA-920 (manufactured by Horiba, Ltd.). As a result of the measurement, the particle diameter was 0.1043 μm.

-Preparation of coating solution for ink receiving layer-
100 parts of the alumina white transparent dispersion obtained above, 10 parts of 7% aqueous solution (binder aqueous solution) of PVA-245 (polyvinyl alcohol having a saponification degree of 88% and an average polymerization degree of 3500, manufactured by Kuraray Co., Ltd.), 7.5 3 parts of 10% aqueous boric acid solution (crosslinking agent aqueous solution), 10% aqueous surfactant solution (Emulgen 109P, manufactured by Kao Corporation, HLB13.6; surfactant), 0.02 part, Superflex 650-5 (Daiichi Kogyo) Cationic polyurethane manufactured by Pharmaceutical Co., Ltd .; 3 parts quaternary ammonium salt type cationic polymer), 2 parts manganese (II) sulfate pentahydrate (manufactured by Kishida Chemical Co., Ltd.), and ammonium sulfate (manufactured by Kishida Chemical Co., Ltd.) ) 40.5 parts of ion-exchanged water, in which 4 parts are dissolved, is kept warm at 60 ° C. before mixing, and each solution after keeping warm is mixed well while keeping the temperature at 60 ° C. It was liquid.

-Formation of ink receiving layer-
And after cooling this coating liquid for ink receiving layers to 50 degreeC, ultrasonic deaeration process was performed for 10 minutes, keeping at 50 degreeC. Immediately after the ultrasonic defoaming treatment, the ink receiving layer coating solution was added to a transparent polyester film (trade name: Lumirror 125T (haze (cloudiness value) according to JIS-K-7105 = 2.19, surface-adhesion treated). (Toray Industries, Inc .; water-resistant support) was applied so that the dry solid content of pseudoboehmite alumina was 40 g / m ² . After coating, set drying was performed for 2 minutes so that the film surface temperature was 20 ° C., and then drying was performed at 80 ° C. for 10 minutes to form an ink receiving layer.
As described above, the inkjet recording sheet of the present invention was produced.

(Example 2)
An ink jet recording sheet was prepared in the same manner as in Example 1, except that manganese sulfate used in the preparation of the ink receiving layer coating solution was replaced with manganese acetate.

(Example 3)
An ink jet recording sheet was prepared in the same manner as in Example 1, except that the manganese sulfate used in the preparation of the ink receiving layer coating solution was changed to manganese nitrate.

(Examples 4 and 5)
An ink jet recording sheet was prepared in the same manner as in Example 1, except that the amount of PVA-245 used in the preparation of the ink receiving layer coating solution was changed to 7 parts and 14 parts, respectively. .

(Example 6)
In Example 1, a coating solution for colloidal silica-containing layer having the following composition was further applied onto the ink receiving layer so that the amount of colloidal silica applied was 0.2 g / m ² and dried to form the uppermost layer. Except that, an ink jet recording medium was produced in the same manner as in Example 1.
<Composition of coating liquid for colloidal silica-containing layer>
・ PL-3 (manufactured by Fuso Chemical Co., Ltd., colloidal silica) 0.5 part ・ Polyfix 700 (manufactured by Showa Polymer Co., Ltd.) 0.1 part ・ PVA-117 (7% aqueous solution, manufactured by Kuraray Co., Ltd.) ... 0.6 parts ・ Swanol AM3130 (manufactured by Nippon Surfactant Co., Ltd.) ... 0.0015 parts

(Comparative Example 1)
A comparative ink jet recording sheet was prepared in the same manner as in Example 1 except that Superflex 650-5 (cationic polymer) was not added in the preparation of the ink receiving layer coating solution of Example 1.

(Comparative Example 2)
For the preparation of a comparative ink jet recording, the same procedure as in Example 1 except that neither 2 parts of manganese (II) sulfate pentahydrate and 4 parts of ammonium sulfate were added in the preparation of the ink receiving layer coating solution of Example 1. A sheet was produced.

(Comparative Example 3)
In Example 1, except that PVA-245 used for the preparation of the ink receiving layer coating liquid was replaced with PVA-145 (saponification degree 99%, average polymerization degree 4500, manufactured by Kuraray Co., Ltd.). In the same manner as in No. 1, a comparative inkjet recording sheet was produced.

(Comparative Example 4)
Example 1 except that PVA-245 used in the preparation of the ink receiving layer coating solution in Example 1 was replaced with PVA-220 (saponification degree 88%, average polymerization degree 2000, manufactured by Kuraray Co., Ltd.). In the same manner as in No. 1, a comparative inkjet recording sheet was produced.

(Comparative Example 5)
Example 1 except that PVA-245 used in the preparation of the ink receiving layer coating solution in Example 1 was replaced with PVA-424 (saponification degree 79%, average polymerization degree 2000, manufactured by Kuraray Co., Ltd.). In the same manner as in No. 1, a comparative inkjet recording sheet was produced.

(Evaluation)
The following measurements and evaluations were carried out for the respective ink jet recording media obtained in the above examples and comparative examples. The results of measurement and evaluation are shown in Table 1 below.

1) Print density Black (Bk) solid printing was performed using an inkjet printer PM-G800 (manufactured by Seiko Epson Corporation). The image density of the solid print portion was measured using Gretag Spectrolino SPM-50 (manufactured by Gretag Macbeth) under the conditions of a viewing angle of 2 °, a light source D50, and no filter.

2) Bronzing Using an inkjet printer PM-A820 (manufactured by Seiko Epson Corporation), cyan solid printing was performed in an atmosphere of 35 ° C./80% RH, and this solid printing portion was visually observed under a fluorescent lamp. Evaluation was performed according to the following evaluation criteria.
<Evaluation criteria>
A: The reflected fluorescent light did not turn red at all, and a good cyan color was maintained.
○: The reflected fluorescent light looked slightly red.
Δ: The reflected fluorescent light looked red.
X: All the light from the reflected fluorescent lamp looked red.

3) Moist heat bleed A black grid line pattern (line width 0.28 mm) was printed on each ink jet recording medium using an ink jet printer (Pixus 850i, manufactured by Canon Inc.), and X light 310TR (manufactured by X light company). ) To measure the magenta concentration (OD1). After printing, leave it at room temperature and humidity for 3 hours, and store it in a constant temperature and humidity chamber at 35 ° C and 80% relative humidity for 3 days. Then measure the magenta concentration (OD) again, The rate was obtained and used as an index for evaluating the bleeding from wet heat.
Moist heat bleed rate (%) = (OD / OD1) x 100

4) Light resistance Solid printing was performed with cyan ink using an inkjet printer PM-G800 (manufactured by Seiko Epson Corporation). The solid printing part was subjected to a light resistance test using an Atlas Fade Meter Ci-35 (manufactured by Atlas Electric Devices Co.) and irradiated with xenon light with an illuminance of 0.39 W / m ² for 30 hours. At this time, the cyan density in the solid print portion was measured before and after the test, and the residual density after the light resistance test was obtained from the following formula, which was used as an index for evaluating the light resistance.
Light resistance (%) = (Concentration after light resistance test / Concentration before light resistance test) × 100

5) Ozone resistance Solid printing was performed with cyan ink using an inkjet printer PM-G800 (manufactured by Seiko Epson Corporation). This solid printed part is put in an ozone exposure tester (manufactured by Suga Test Instruments Co., Ltd.) and left in ozone at a concentration of 2.7 ppm for 2.5 hours under an environmental condition of 40 ° C. and 55% RH. A resistance test was performed. At this time, the cyan density in the solid printing part was measured before and after the test, and the residual density ratio after the ozone resistance test was obtained from the following formula, which was used as an index for evaluating the ozone resistance.
Gas resistance (%) = (concentration after ozone resistance test / concentration before ozone resistance test) × 100

6) Ink absorption speed Recording was performed using a color ink jet printer PM-770C (manufactured by Seiko Epson Corporation), and after the recording was completed, the time until the print portion was lightly rubbed with a fingertip and no stain was measured was measured. Evaluation was performed according to the evaluation criteria. The allowable degree is 4 or more.
<Evaluation criteria>
5: The ink absorption speed was less than 10 seconds.
4: The ink absorption speed was 10 seconds or more and less than 30 seconds.
3: The ink absorption speed was 30 seconds or more and less than 60 seconds.
2: The ink absorption speed was 1 minute or more and less than 5 minutes.
1: The ink absorption speed was 5 minutes or more.

7) Glossiness Black (Bk) solid printing was performed using an inkjet printer PM-G800 (manufactured by Seiko Epson Corporation). The glossiness of this solid image portion was measured at an incident angle of 60 ° and a received light of 60 ° using a digital variable gloss meter UGV-5D (measuring hole 8 mm, manufactured by Suga Test Instruments Co., Ltd.).

As shown in Table 1, in the example, an image excellent in light resistance and ozone resistance was obtained, and generation of wet heat bleeding in the image could be suppressed. Further, the image density, ink absorbability and glossiness were also good.
On the other hand, in the comparative example, it was not possible to achieve both light resistance and ozone resistance and prevention of wet heat bleeding, and an image that could be stably held at a high concentration without discoloration for a long period of time was not obtained. In Comparative Example 5, the degree of saponification of PVA was too low and bronzing deteriorated.

Claims (7)

  A quasi-boehmite-like alumina hydrate, polyvinyl alcohol having a saponification degree of less than 90% and an average polymerization degree of 3000 or more, a crosslinking agent that crosslinks at least polyvinyl alcohol, and quaternary ammonium are contained in the skeleton on the water-resistant support. An ink jet recording medium having an ink receiving layer containing a cationic polymer, a water-soluble manganese compound, and ammonium sulfate.   The inkjet recording medium according to claim 1, wherein at least one of the crosslinking agents is boric acid and / or a salt thereof.   The ink jet recording medium according to claim 1, wherein the ink receiving layer comprises a plurality of layers, and the uppermost layer contains colloidal silica.   The mass ratio (al / PVA) of the pseudo boehmite-like alumina hydrate (al) and the polyvinyl alcohol (PVA) is 7.5 to 13, wherein any one of claims 1 to 3 is provided. 2. An ink jet recording medium according to item 1.   The inkjet recording medium according to any one of claims 1 to 4, wherein the cationic polymer has a polyurethane skeleton.   On a water-resistant support, pseudoboehmite-like alumina hydrate, polyvinyl alcohol having a saponification degree of less than 90% and a polymerization degree of 3000 or more, a crosslinking agent that at least crosslinks polyvinyl alcohol, and a cation containing quaternary ammonium in the skeleton A method for producing an ink jet recording medium, wherein a preparation liquid prepared by mixing latex, a water-soluble manganese compound, and ammonium sulfate is applied to form an ink receiving layer. Preparing an alumina dispersion in which the pseudo boehmite-like alumina hydrate is dispersed in an aqueous solvent with a high-pressure disperser;
Mixing the alumina dispersion, the aqueous solution containing the polyvinyl alcohol, the crosslinking agent, the cationic latex, the water-soluble manganese compound, and the ammonium sulfate to prepare a coating solution;
Applying the prepared coating solution on a water-resistant support to form an ink receiving layer;
The method for producing an ink jet recording medium according to claim 6, wherein: