JPH0999635A - Ink jet recording sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording sheet excellent in ink absorbability, excellent in the glossiness and transparency of a high density part and not generating the lowering of image quality caused by image irregularity generated during the presevation before recording. SOLUTION: In an ink jet recording sheet wherein an ink receiving layer is provided on at least one surface of a support, the ink receiving layer contains an anionic urethane polymer with glass transition temp. of 60 deg.C or higher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording sheet, and more particularly to an ink jet recording sheet having improved gloss or transparency in a high density area.

[0002]

2. Description of the Related Art In recent years, ink jet recording type printers have been rapidly spread with the spread of personal computers. Especially, its use is drawing attention in the fields of printing and design where high image quality is required.

As a recording sheet used in the ink jet recording system, a recording sheet having an ink receiving layer (hereinafter, also referred to as an ink absorbing layer) provided on a support which is conventionally called a normal paper or an ink jet recording sheet is used. Sheets have been used. However, when these recording sheets are used, they cannot be used in the above-mentioned fields where high resolution and high gloss are required, such as ink bleeding and low gloss.

Further, even if a transparent support is used as an original for an OHP (overhead projector), there is a problem that the porous ink absorbing layer deteriorates the light transmittance.

In order to solve these problems, it has been proposed to use gelatin as an ink absorbing layer having high light transmittance and excellent water-based ink receptivity. For example, JP
9-255131 discloses the use of gelatin as a high ink absorption layer, and is disclosed in JP-A-62-263.
No. 084 discloses a receiving layer formed of gelatin having a specific pH. Further, JP-A-1-146784 discloses the combined use of acid-treated gelatin and a fluorine-containing surfactant. JP-A-6-64306 discloses that gelatin which has been applied is once in a gel state and then dried by a cold dry method. A recording sheet obtained by doing so has been proposed.

It is true that the receiving layer using these gelatins has excellent ink absorption characteristics and high gloss and light transmittance, but the gloss and transparency are deteriorated in the high density area after ink jet recording. There was found. For example, in a reflective inkjet recording sheet using resin-coated paper, cast-coated paper, synthetic paper or the like as a support, there arises a problem that the glossiness of a high density portion is lowered,
It has been found that in a transmissive inkjet recording sheet using a transparent support such as a plastic film as a support, the transparency of the high density portion is lowered.

On the other hand, it is possible to improve the ink absorbency by using a polyurethane resin.
181, 61-92886, 61-13578.
6, 61-158495, U.S. Pat. No. 4,578,
No. 285, No. 4,642, 247, No. 4, 849, 2
Known as No. 86. However, the ink absorbency is not sufficient even when the composition containing the polyurethane resin described in these patents is used, and when the sheet before recording is aged for several months after production, it causes image unevenness. It was found that the image quality deteriorates. Especially 3
It was found that the image quality was remarkably deteriorated when stored at a high temperature of 0 ° C or higher.

[0008]

SUMMARY OF THE INVENTION It is, therefore, a first object of the present invention to provide an ink jet recording sheet which is excellent in ink absorption and is excellent in glossiness and transparency in a high density area.

Another object of the present invention is to provide an ink jet recording sheet of high image quality which does not cause image quality deterioration due to image unevenness caused by storage before recording.

[0010]

As a result of intensive studies, the object of the present invention has been achieved by the following constitution.

(1) In an ink jet recording sheet having an ink receiving layer provided on at least one side of a support, the ink receiving layer contains an anionic urethane polymer having a glass transition temperature of 60 ° C. or higher. Characteristic inkjet recording sheet.

(2) The ink jet recording sheet according to the above item 1, wherein the ink receiving layer contains polyvinylpyrrolidone.

(3) Gelatin in the ink receiving layer, or
1) or 2) which has a gelatin derivative
Ink jet recording sheet according to the item.

(4) The ink jet recording sheet according to the above item 3, wherein the gelatin derivative is arylcarbamoyl gelatin.

(5) The ink jet recording sheet as described in the above item 1, 2, 3 or 4, wherein the anionic urethane polymer is a self-emulsifying latex polymer.

The present invention will be described in detail below.

The anionic urethane polymer according to the present invention is an addition polymerization product of a polyisocyanate compound and a polyol having two or more hydroxyl groups, and is a urethane polymer having an anionic group at its side chain or terminal.

The urethane polymer used in the present invention is preferably an aqueous dispersion that does not require the use of an organic solvent at the time of coating from the viewpoint of environmental problems. There are two types of urethane polymer aqueous dispersions: a "forced emulsification type" which emulsifies by using an external surfactant and a "self-emulsifying type" which emulsifies after introducing hydrophilicity into the urethane polymer skeleton. In the present invention, any type can be used, but it is preferable that the ink jet recording sheet is “self-emulsifying type” in terms of gloss and transparency.

Polyisocyanates useful for forming polyurethanes include 1,2-diisocyanate ethane, 1,3-diisocyanate propane, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, nona as those having two isocyanate groups. Methylene diisocyanate, decamethylene diisocyanate, ω, ω'-dipropyl ether diisocyanate, cyclohexane-1,4-diisocyanate, dicyclohexylmethane-4,4'-
Diisocyanate, hexahydrodiphenyl-4,4 '
-Diisocyanate, hexahydrodiphenyl ether-4,4'-diisocyanate, phenylene-1,4-
Diisocyanate, toluylene-2,6-diisocyanate, toluylene-2,4-diisocyanate, 1-methoxybenzene-2,4-diisocyanate, 1-chlorophenylene diisocyanate, tetrachlorophenylene diisocyanate, metaxylylene diisocyanate, paraxylylene diisocyanate, Diphenylmethane-4,4'-diisocyanate, diphenylsulfide-4,4'-diisocyanate, diphenylsulfone-4,4-'diisocyanate, diphenylether-
4,4'-diisocyanate, diphenyl ether-
3,4'-diisocyanate, diphenyl ketone-4,
4'-diisocyanate, naphthalene-1,4-diisocyanate, naphthalene-1,5-diisocyanate,
2,4'-biphenyl diisocyanate, 4,4'-biphenyl diisocyanate, 3,3'-dimethoxy-
4,4'-biphenyl diisocyanate, anthraquinone-2,6-diisocyanate, triphenylmethane
4,4'-diisocyanate, azobenzene-4,4 '
-Diisocyanate and the like.

As the compound containing three isocyanate groups, for example, compounds represented by the following structural formulas (I) to (IV) can be used.

[0021]

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Suitable polyols having two or more hydroxyl groups include diols such as ethylene glycol, diethylene glycol, triethylene glycol and propylene glycol, trimethylolethane, trimethylolpropane, hexanetriol and glycerin. Triols, hexaols such as sorbitol, polyester polyols, polyether polyols, polyester polyether polyols are mentioned. The polyester polyol is a compound produced from a polybasic acid and a polyhydroxy compound, and a terminal hydroxy polyester is preferable. Is. As polybasic acids, oxalic acid,
Saturated fatty acids such as succinic acid, adipic acid and pimelic acid, unsaturated fatty acids such as maleic acid and fumaric acid, phthalic acid,
An aromatic acid such as isophthalic acid or an anhydride thereof is used alone or as a mixture, and as a polyhydroxy compound, diols such as ethylene glycol, diethylene glycol, triethylene glycol, and propylene glycol, trimethylolpropane, trimethylolethane, hexanetriol, glycerin, etc. Or one or more of hexaols such as triol and sorbitol.

The polyether polyol used in the present invention is a compound containing two or more hydroxyl groups in one molecule and having an ether bond, and is a homopolymer of ethylene oxide (EO) and propylene oxide (PO). Or a copolymer, and a polyhydric alcohol such as glycerin, trimethylolpropane, triol such as hexanetriol, hexaol such as sorbitol, or ethylenediamine, benzenesulfamide, 2-aminoethanolamine, N-methyldiethanolamine, diethylenetriamine, aroma To an amine such as an amine having a group, E
A polyol formed by optionally adding O or PO,
Or derivatives thereof, and one or two of these
More than one species can be mixed and used. The polyester polyether polyol is obtained by condensing the above polybasic acid and polyether polyol so as to be a terminal hydroxyl group.

Examples of other polyols include castor oil, tall oil or their derivatives, acrylic polyol, urethane polyol and the like. Further, the above-mentioned various polyols can be used alone or as a mixture.

Any polyurethane can be prepared by a known method from the above components.

The glass transition temperature of the urethane polymer of the present invention is 60 ° C. or higher, preferably 70 ° C. or higher. It has been found that when the glass transition temperature is 60 ° C. or lower, the problem of deterioration of the uniformity of the image area occurs during long-term storage.

The glass transition temperature can be measured by a known method by utilizing the fact that the coefficient of thermal expansion and the specific heat change discontinuously in the process of changing the temperature.

The anionic urethane polymer usable in the present invention is preferably a "self-emulsifying type" in which an anionic group is introduced into the urethane polymer skeleton and then emulsified.

Typical examples of the anionic group are:
A carboxyl group, a sulfonic group, a sulfate group, a phosphate group and the like.

A method for preparing these self-emulsifying anionic urethane polymers is described in JP-B-43-9076.
42-24194, JP-A-50-112490,
The methods described in JP-A-51-60294, JP-B-49-28653, JP-A-46-15517 and JP-A-51-36294 can be used.

In the present invention, it is preferable to use gelatin as the binder used in the ink receiving layer of the ink jet recording sheet.

As the gelatin, any gelatin made from animal collagen can be used, but gelatin made from pig skin, cowhide and cow bone collagen is preferable. Further, the kind of gelatin is not particularly limited, but lime-processed gelatin, acid-processed gelatin, gelatin derivatives (for example, Japanese Patent Publication Nos. 38-4854 and 39-39).
No. 5514, No. 40-12237, No. 42-2634.
5, US Pat. Nos. 2,525,753 and 2,594,
No. 293, No. 2,614,928, No. 2,763,6
No. 39, No. 3,118,766, No. 3,132,94
No. 5, No. 3,186,846, No. 3,312,553
And the gelatin derivatives described in British Patents Nos. 861,414, 103,189, etc.) can be used alone or in combination.

The term "derivative gelatin" as used in the present invention means gelatin having an amino group, an imino group or a carboxyl group, which gelatin has, but in the present invention, a gelatin having an amino group or an imino group substituted is particularly preferable. More preferably, the amino group-substituted gelatin is used, and examples thereof include phenylcarbamoyl gelatin and phthalated gelatin.

In the present invention, the derivative gelatin obtained by substituting the amino group is, for example, US Pat.
Nos. 91,582, 2,614,928, 2,52
5,753, etc.

In the present invention, useful substituents for obtaining a derivative gelatin by substituting the amino group include (a)
Alkylacyl, arylacyl, acetyl and substitution,
Acyl groups such as unsubstituted benzoyl, (b) sulfonyl groups such as alkylsulfonyl and arylsulfonyl, (c)
Carbamoyl groups such as alkylcarbamoyl and arylcarbamoyl; (d) thiocarbamoyl groups such as alkylthiocarbamoyl and arylthiocarbamoyl; (e) linear and branched alkyl groups having 1 to 18 carbon atoms; (f) substituted and unsubstituted And aryl groups such as aromatic heterocycles such as phenyl, naphthyl and pyridyl and furyl.

Of these, the derivative gelatin in the present invention is preferably one in which the amino group is substituted with an acyl group (-COR ¹ ) or a carbamoyl group (-CONR ¹ R ² ).

R ¹ of the acyl group or carbamoyl group is a substituted or unsubstituted aliphatic group (eg, an alkyl group having 1 to 18 carbon atoms, an allyl group, etc.), an aryl group or an aralkyl group (eg, a phenethyl group, etc.). And R ² is a hydrogen atom, an aliphatic group, an aryl group or an aralkyl group.

Particularly preferred in the present invention is R ¹
Is an aryl group, and R ² is a hydrogen atom. Hereinafter, examples of the amino group substituent of the derivative gelatin used in the present invention are shown, but the present invention is not limited thereto.

-Examples of Amino Group Substituents of Derivative Gelatin-

[0040]

Embedded image

In the derivative gelatin in the present invention, 60% or more of the total amount of at least one selected from an amino group and an imino group is capable of reacting with the amino group or the imino group in order to quickly absorb the ink into the receiving layer. It is preferable to use those which have been previously substituted with groups, and it is particularly preferable to use a derivative gelatin in which 80% or more of the total amount of amino groups is substituted.

The jelly strength of the gelatin according to the present invention (PA
GI method, by Bloom type jelly strength meter) is 1
It is preferably 50 g or more, and particularly preferably 200 to 300 g.

In the present invention, the coating amount of gelatin or gelatin derivative contained in the ink receiving layer is 0.
5 to 30 g / m ² is preferable, and more preferably 1 to 2
It is 0 g / m ² . Gelatin in the ink receiving layer is 0.5
If it is less than g / m ² , the ink receptivity is poor and the ink overflows from the receptive layer after printing. Further, when the amount is more than 30 g / m ² , the ink receptivity is improved, but problems such as cracking and curling are likely to occur.

In the present invention, it is preferable to use the anionic urethane polymer of the present invention in combination with gelatin and the following polymers for the purpose of improving ink receptivity and dot reproducibility. Examples of the polymers to be used in combination include vinyl formal such as polyvinyl alcohol, polyvinylpyrrolidone, polyvinylpyridinium halide, various modified polyvinyl alcohols, and derivatives thereof (JP-A-60-60).
-145879, 60-220750, 61-
No. 143177, No. 61-235182, No. 61-2
No. 35183, No. 61-237681, No. 61-26.
No. 1089), polyacrylamide, polydimethylacrylamide, polydimethylaminoacrylate, polyacrylic acid soda, acrylic acid methacrylic acid copolymer salt, polymethacrylic acid sodium salt, acrylic acid vinyl alcohol copolymer salt, etc. Polymer (described in JP-A-60-168651 and JP-A-62-1988), starch, oxidized starch, carboxyl starch, dialdehyde starch, cationized starch, dextrin, sodium alginate, gum arabic, casein, pullulan, dextran, Natural polymer materials such as methyl cellulose, ethyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose and their derivatives (Japanese Patent Laid-Open No. 59-174).
No. 382, No. 60-262885, No. 61-1431
No. 77, No. 61-181679, No. 61-19387
9 and 61-287782), polyethylene glycol, polypropylene glycol, polyvinyl ether, polyglycerin, maleic acid alkyl vinyl ether copolymer, maleic acid-N-vinylpyrrole copolymer, styrene-maleic anhydride copolymer. Polymers, synthetic polymers such as polyethyleneimine (JP-A-61-32787)
No. 61-237680, No. 61-277483, etc.) and the like. Of these polymers, polyvinylpyrrolidones, polyvinyl alcohols, and methacrylic acid / acrylic acid copolymers and salts thereof are preferable.

Particularly preferred are polyvinylpyrrolidones having an average molecular weight of 100,000 to 500,000 and polyvinyl alcohol having a molecular weight of 20,000 to 70,000, which are excellent in image resolution and uniformity and do not affect the image resolution even when stored for a long period of time. It is a kind.

In the present invention, the addition ratio (weight) of polymer to gelatin is from 1/20 to 2/1, preferably from 1/10 to 1/1 from the viewpoint of ink receptivity and dot reproducibility. preferable.

In the present invention, the ink receiving layer may be hardened with an appropriate hardener for the purpose of improving water resistance and dot reproducibility. Specific examples of the hardener include aldehyde compounds such as formaldehyde and glutaraldehyde, ketone compounds such as diacetyl and chlorpentanedione, bis (2-chloroethylurea), 2-hydroxy-4,6-dichloro-1. , 3,5-triazine,
Reactive halogen-containing compounds such as those described in US Pat. No. 3,288,775, divinyl sulfone, US Pat.
Compounds having a reactive olefin as described in US Pat. No. 635,718, N-methylol compounds described in US Pat. No. 2,732,316, isocyanates as described in US Pat. No. 3,103,437, US Pat. , 280,
No. 2,983,611, aziridine compounds, US Pat. No. 3,100,704, carbodiimide compounds, US Pat. No. 3,091,537, epoxy compounds, and mucochloric acid, halogen carboxy. There are aldehydes, dioxane derivatives such as dihydroxydioxane, chromium alum, potassium alum, and inorganic hardeners such as zirconium sulfate, and these may be used alone or in combination of two or more. The amount of the hardener added is 100 g of the binder that constitutes the ink receiving amount.
Is preferably 0.01 g to 10 g, and more preferably 0.1 to 5 g. However, as an embodiment for carrying out the present invention, no hardener is used.

That is, when a hardening agent is used, the effect of the present invention becomes small, and since the hardening film changes with time, there is a problem in that the ink absorbency and the image resolution change depending on the time of use, which is not preferable.

In the present invention, the ink receiving layer further contains a surfactant, a binder, an inorganic pigment, a coloring dye, a coloring pigment, an ink dye fixing agent, an ultraviolet absorber, an antioxidant, and a pigment dispersant. Various known additives such as a defoaming agent, a leveling agent, a fluorescent brightening agent, a viscosity stabilizer, and a pH adjusting agent can be added.

As a method for applying the ink receiving layer coating liquid in the present invention, a commonly used application method (for example, curtain method, extrusion method, air knife method,
Roll coating method, rod bar coating method, etc.) are used.

In the present invention, the ink receiving layer may have a single layer structure or a multilayer structure. Examples of the multi-layer structure include JP-A Nos. 57-89954, 60-224578 and 61.
Examples thereof include those described in No. 12388 and the like. For example, the ink permeable layer described in JP-A-61-2138 may be further received on the ink receiving layer of the present invention.

In the present invention, the ink receiving layer is provided on at least one side of the support, but a preferred embodiment of the present invention is to provide a layer called a back layer different from the ink receiving layer. By providing the back layer, curling of the recording paper and sticking of the surfaces due to changes in temperature and humidity can be prevented.

The pH of the film surface of the ink receiving layer of the present invention is 3
-10 is preferable and 4-8 is especially preferable. pH
When the value is less than 3, glossiness is lost, and when the pH exceeds 10, the whiteness of the unprinted part deteriorates over time.

As the support used in the present invention, either a transparent support or an opaque support can be used depending on the purpose of use.

As the transparent support, any of the conventionally known supports can be used, and examples thereof include films of polyester resin, cellulose acetate resin, acrylic resin, polycarbonate resin, polyvinyl chloride resin, polyimide resin, cellophane, celluloid and the like. is there. Among these, a polyester resin, particularly a polyethylene terephthalate film, is preferable from the viewpoint of rigidity and transparency of the support.

Such a transparent support has a thickness of about 10
About 200 μm, more preferably 5 μm
It is about 0 to 150 μm.

As the opaque support, any conventionally known one such as resin-coated paper, pigment-containing opaque film, foamed film and the like can be used, but resin-coated paper and various films are preferable from the viewpoint of glossiness and smoothness, and the touch is good. A resin-coated paper, a polyolefin resin-coated paper, and a polyester film are more preferable from the viewpoint of feeling and high quality.

The base paper which constitutes the resin-coated paper which is preferably used is not particularly limited, and commonly used paper can be used, but more preferably, for example, a smooth base paper used for a photographic support is used. preferable. As the pulp constituting the base paper, natural pulp, recycled pulp, synthetic pulp or the like may be used alone or in combination of two or more. Additives such as a sizing agent, a paper strength enhancer, a filler, an antistatic agent, an optical brightening agent and a dye, which are generally used in papermaking, are added to the base paper.

Further, a surface sizing agent, a surface paper strength agent, a fluorescent whitening agent, an antistatic agent, a dye, an anchoring agent and the like may be coated on the surface.

The thickness of the thick paper is not particularly limited, but it is preferable that the paper has good surface smoothness, such as being compressed by applying a pressure with a calendar or the like during or after the paper is made, and its weight is from 30 to 30. 250 g / m ² is preferred.

As the resin for the resin-coated paper, a polyolefin resin or a resin curable with an electron beam can be used.
Examples of the polyolefin resin are low-density polyethylene, high-density polyethylene, polypropylene, polybutene, a homopolymer of an olefin such as polypentene or a copolymer of two or more olefins such as an ethylene-propylene copolymer and a mixture thereof, Those having various densities and melt viscosity indices (melt index) can be used alone or in combination.

In the resin of the resin-coated paper, white pigments such as titanium oxide, zinc oxide, talc and calcium carbonate, fatty acid amides such as stearic acid amide and arachidic acid amide, zinc stearate, calcium stearate, stearic acid. Aluminum, fatty acid metal salts such as magnesium stearate, antioxidants such as Irganox 1010 and Irganox 1076, blue pigments and dyes such as Cobalt Blue, Ultramarine Blue, Cecilian Blue, Phthalocyanine Blue, Cobalt Violet, Fast Violet, Manganese Purple It is preferable to add various additives such as magenta pigments and dyes, fluorescent whitening agents, and ultraviolet absorbers in an appropriate combination.

The resin-coated paper, which is a support preferably used in the present invention, is produced by a so-called extrusion coating method in which a resin melted by heating is cast in the case of a polyolefin resin on a running base paper, and both sides of the resin are coated. Is covered by. In the case of a resin that is cured by an electron beam, the resin is applied by a commonly used coater such as a gravure coater or a blade coater, and then irradiated with an electron beam to cure and coat the resin. Further, before coating the resin on the base paper, the base paper is preferably subjected to an activation treatment such as a corona discharge treatment or a flame treatment. The surface (surface) of the support on which the ink receiving layer is applied has a glossy surface, a matte surface, and the like, depending on the application, and the glossy surface is used particularly advantageously. It is not necessary to coat the back surface with a resin, but it is preferable to coat the resin from the viewpoint of preventing curling. The back surface is usually a matte surface, and the front surface or both front and back surfaces can be subjected to an activation treatment such as a corona discharge treatment or a flame treatment as required. The thickness of the coating resin layer is not particularly limited, but is generally 5 to 50 μm and is coated on the surface or both front and back surfaces.

The ink suitable for the ink jet recording sheet of the present invention is a water-based ink, and the water-based ink is a recording liquid containing the following colorant, liquid medium and other additives. As the colorant, direct dye, acid dye,
Examples thereof include basic dyes, reactive dyes, and water-soluble dyes such as food dyes.

As the solvent for the aqueous ink, water and various water-soluble organic solvents such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, sec-butyl alcohol, t
ert-butyl alcohol, isobutyl alcohol, and other alkyl alcohols having 1 to 4 carbon atoms; amides such as dimethylformamide and dimethylacetamide; ketones and ketone alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; Polyalkylene glycols such as polyethylene glycol and polypropylene glycol; alkylene groups such as ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol and diethylethylene glycol. 2-6 alkylene glycols; glycerin, ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether, trie Glycol, lower alkyl ethers of polyhydric alcohols such as mono-methyl ether,
Pyrrolidinones such as 2H-pyrrolidinone, 1-methyl-
Examples thereof include pyrrolidones such as 2-pyrrolidone and 2-pyrrolidone. Among these many water-soluble organic solvents,
Preferred are polyhydric alcohols such as diethylene glycol, lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl ether and triethylene glycol monoethyl ether, and pyrrolidones.

In the present invention, it is preferable to use a mixed solvent of water and the organic solvent as the solvent of the ink from the viewpoint of preventing clogging of the ink head nozzle. At this time, the mixing ratio of water and the organic solvent is 1 by weight. / 9 to 9/1 is preferable, and more preferably 4/6 to 9/1.

Other additives include, for example, a pH adjusting agent, a sequestering agent, an antifungal agent, a viscosity adjusting agent, a surface tension adjusting agent, a wetting agent, a surfactant and a rust preventive agent.

[0068]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In the following description, “part” means part by weight. Example 1 Resin-coated paper (20 g / m ^{2 of a} resin composition consisting of low-density polyethylene (70 parts) and high-density polyethylene (20 parts) was applied to the surface of a base paper having a basis weight of 100 g, and low-density polyethylene ( 50 parts) and high density polyethylene (50 parts)
20 g / m ^{2 of a} resin composition consisting of) was applied to the surface by a bar coating method so that the film weight after drying was 10 g / m ^2, and then dried. Then, an ink jet recording sheet sample was obtained.

<Coating liquid composition for ink receiving layer> Lime-treated gelatin (Bloom strength; 250 g) 39.7 parts by weight PVP-K90 (BASF) 30 parts by weight Additive polymer A (described in Table 1) 30 parts by weight Surfactant (Megafax F-120) 0.3 parts by weight * Solid content concentration of coating solution 8% (wt / vol) Coating solution pH: adjusted to 7.5 using a 5% NaOH aqueous solution.

The composition of each ink at this time is as follows.

Y: Direct Yellow 50 (CI.29025) 6 parts Diethylene glycol 47 parts Water 47 parts M: Xylene Red B (CI.45100) 6 parts Diethylene glycol 47 parts Water 47 parts C: Light Green SF Yellowish 6 parts Diethylene glycol 47 Part water 47 parts Next, a part of the sample obtained was used for ink jet printer (M
Using J-5000C, manufactured by Epson, each color of yellow (Y), magenta (M), cyan (C), blue (B), green (G), red (R), and black (K) is printed. Then, the unevenness and glossiness of the uniform image area were observed and evaluated, and the sample was stored in a cool dark place. This sample is referred to as (A).

Next, the rest of the sample was stored for 1 month in an environment of 30 ° C.-55% RH and evaluated in the same manner as above. This sample is referred to as (B).

The evaluation method is shown below.

<Uniformity in uniform image area, unevenness: B, G,
Each color of R and K was printed at the maximum density, and the uniformity of this maximum density part was visually evaluated> Evaluation criteria ◎: No codling or unevenness was observed with the naked eye, and it was uniform ○: Some codling or unevenness Existence, but cannot be recognized without staring. Δ: Presence of cod and unevenness can be confirmed at one eye, but practically acceptable. X: Codling and unevenness are remarkable, which is a problem in practical use.

<Glossiness: The uniform image area of K was visually observed and the degree of glossiness thereof was judged> Evaluation Criteria ◯: Excellent without problems Δ: Gloss slightly lost, but practically problematic There is no x: The gloss is lost and it cannot be practically used.

[0076]

[Table 1]

As is clear from the results shown in Table 1, the use of the anionic urethane polymer having a high glass transition temperature according to the present invention deteriorates the uniformity of the image area even when the sample is printed after being stored for a long period of time. And no deterioration of glossiness was observed,
Good results have been obtained. In particular, it can be seen that good results can be obtained by using a self-emulsifying anionic urethane polymer having a high glass transition temperature.

Example 2 Sample No. 1 in the coating composition for ink receiving layer of Example 1
The addition polymer A used in −2, 1-6 was changed as shown in Table 2, and the same evaluation as in Example 1 was performed. However, the storage period was two months.

Table 2 shows the results.

[0080]

[Table 2]

As is clear from Table 2, when the amount of the polymer A added is 1.0 g / m ^{2 to} 3.5 g / m ² , the image uniformity and the glossiness do not change before and after aging, and both are excellent. I understand.

Example 3 PVP-K of the coating liquid composition for the ink receiving layer in Example 1
The same evaluation as in Example 1 was performed except that 90 was changed as the combined polymer as shown in Table 3.

The results are shown in Table 3. As the added polymer A, Superflex 126 (Daiichi Kogyo Seiyaku Co., Ltd.)
Manufactured) was used, and the addition amount was 3 g / m ² .

[0084]

[Table 3]

As is clear from Table 3, it is found that the image uniformity is kept high and the image is not deteriorated by using other polymers together.

Example 4 Except that a transparent polyethylene terephthalate film having a film thickness of 100 μm was used as the base material for coating the ink receiving layer.
It carried out similarly to Example 1. However, instead of the gloss evaluation, the transparency was evaluated based on the following criteria.

<Transparency: A red uniform image portion composed of M ink and Y ink was visually observed with transmitted light and its transparency was judged> Evaluation criteria ◯: Excellent without problems Δ: Slightly transparency Is lost, but there is no problem in practical use. X: Table 4 shows the results in which transparency is lost and it cannot be used practically.

[0088]

[Table 4]

As is clear from the results in Table 4, even when a transparent support is used, the use of the urethane polymer of the present invention causes deterioration of the uniformity of the image area and the deterioration of transparency even during long-term storage. No good results were obtained.

Example 5 A sample was prepared by using the gelatin derivative shown in Table 5 in place of the lime-processed gelatin in the composition of the ink receiving layer coating solution of the sample 1-2 of Example 1. The evaluation is Example 1
Image uniformity and glossiness were evaluated in the same manner as in.

[0091]

[Table 5]

As is clear from Table 5, the image uniformity is further improved by using the aryl carbamoyl gelatin which is a gelatin derivative.

[0093]

According to the constitution of the present invention, an ink jet recording sheet is obtained which has good image uniformity and glossiness and is not deteriorated with time.

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Claims (5)

[Claims] 1. An ink jet recording sheet having an ink receiving layer provided on at least one side of a support, wherein the ink receiving layer contains an anionic urethane polymer having a glass transition temperature of 60 ° C. or higher. Inkjet recording sheet to be. 2. The ink jet recording sheet according to claim 1, wherein the ink receiving layer contains polyvinylpyrrolidone. 3. The ink jet recording sheet according to claim 1, wherein the ink receiving layer contains gelatin or a gelatin derivative. 4. The ink jet recording sheet according to claim 3, wherein the gelatin derivative is arylcarbamoyl gelatin. 5. The ink jet recording sheet according to claim 1, 2, 3 or 4, wherein the anionic urethane polymer is a self-emulsifying latex polymer.