JPH11348409A - Ink jet recording paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an image from smearing without lowering light-fastness by providing an ink absorbing layer containing a hydrophilic binder and cationic composite particles consisting of inorganic fine particles having primary particles of an average particle diameter or lower and a water soluble cationic polymer having a molecular weight of a predetermined quantity or lower expressed by a specific formula. SOLUTION: There is provided on a support with an ink jet absorbing layer that contains a cationic composite particles made up of a hydrophilic binder and cationic composite particles consisting of inorganic fine particles having primary particles of an average particle diameter of about 30 nm or lower and water soluble cationic polymer having an average molecular weight of about 100000 or lower expressed by formula. In the formula, R and R' denote hydrogen atoms or 1-4C alkyl groups, R1 -R3 and R'1 -R'3 are alkyl groups, A and J are bivalent combination groups, X1 and X2 are anion groups, Q is a repeat unit derived from a monomer having an ethylene unsaturated group (also included in the case of copolymerization of two or more kinds of simple substances), (x) is 10-90 mol.%, (y) is 5-90 mol.%, (z) is 0-60 mol.%, and (m) shows integers of 1-6.

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 image bleeding after printing without deteriorating light fastness.

[0002]

2. Description of the Related Art Ink-jet recording is a method in which fine droplets of ink are caused to fly according to various operating principles and adhere to a recording sheet such as paper to record images and characters. It has advantages such as easy noise and multicoloring. With regard to nozzle clogging and maintenance, which has been a problem in the past, improvements have been made in both ink and equipment, and are now rapidly spreading in various fields such as various printers, facsimile machines, and computer terminals. .

[0003] The recording paper used in this ink jet recording system has a high density of print dots, a bright and vivid color tone, and the ink is absorbed quickly so that even when the print dots overlap, the ink may flow out. It is required that bleeding does not occur, that the diffusion of print dots in the horizontal direction is not unnecessarily large, and that the periphery is smooth and not blurred.

[0004] In particular, when the ink absorption speed is low, when ink droplets of two or more colors are printed in an overlapping manner, the droplets cause a repelling phenomenon on the recording paper to become uneven, It is necessary for recording paper to have a high ink absorbency because the colors of each other are blurred in the boundary region of, and the image quality is easily deteriorated.

[0005] To solve these problems, a great many techniques have been proposed. For example, JP
JP-A-5-53012 describes a recording paper in which a coating for surface processing is wetted on a low-size base paper.
No. 5830, a recording paper provided with an ink-absorbing coating layer on the surface of a support, and a non-colloidal silica powder as a pigment in a coated layer described in JP-A-56-157. Recording paper, a recording paper using a combination of an inorganic pigment and an organic pigment described in JP-A-57-107878,
JP-A-58-11287 discloses a recording paper having two pore distribution peaks.
No. 1782, recording paper comprising two upper and lower porous layers, JP-A-59-68292 and JP-A-59-12.
Recording papers having irregular cracks described in JP-A Nos. 3696 and 60-18383.
No. 135786, No. 61-148092 and No. 62
And recording paper having a fine powder layer described in JP-A-149475, JP-A-63-252779,
-108083, 2-136279, 3-65
JP-A-57-14091 and JP-A-60-2190, which are described in JP-A-57-14091 and JP-A-60-2190.
No. 83, No. 60-210984, No. 61-20797
No. 61-188183, JP-A-5-278324
Nos. 6-92091, 6-183134, 7
Recording paper containing fine-particle silica such as colloidal silica described in JP-A-137431 and JP-A-7-276789, and JP-A-2-276671, JP-A-3-27671.
Nos. 67684, 3-215082 and 3-25
No. 1488, No. 4-67986, No. 4-263983
And a large number of recording papers containing alumina hydrate fine particles described in JP-A-5-16517 and JP-A-5-16517 are known.

[0006] Among them, a gap type recording paper using minute inorganic fine particles and a hydrophilic binder and having minute gaps formed in the ink receiving layer is preferable as a high quality glossy paper because relatively high gloss can be obtained. It is.

It is preferable to use fine particle silica having an anionic surface as such inorganic fine particles because excellent gloss can be obtained. In particular, the average particle size of primary particles synthesized by a gas phase method is preferable. Composite particles having an average particle size of 100 nm or less, which are obtained by combining a fine particle silica having a particle size of 30 nm or less and a cationic polymer, are particularly preferable because they can achieve both glossiness and high porosity.

By the way, after ink-jet recording, there is a problem that the recorded image tends to bleed when stored under high humidity or when water droplets adhere thereto. Many techniques have been proposed for solving this problem. JP 57
JP-A-36-6969 discloses the use of a basic mordant latex.
Nos. 86 and 59-198188 disclose a method of impregnating polyethyleneimine, and JP-A-58-24492 discloses an electrolyte polymer having a cationic group.
Japanese Patent Application Laid-Open No. Sho 61-197979 discloses that a cationic polymer mordant and a polymer having a hydrophilic group are contained.
61887, 61-72581, 61-252
Nos. 189 and 62-174184 disclose the use of polyallylamine as a mordant.
No. 62275 discloses the use of a combination of a cationic mordant and a cationic surfactant, and JP-A-6-143798 discloses a cation-modified polyvinyl call.
No. 96 describes that specific two kinds of cationic polymers are used in combination to improve water resistance.

Further, JP-A-59-20696 and JP-A-59-20696 are similar.
No. 33176, No. 59-33177, No. 59-96
987, 59-155088, 60-1138
No. 9, No. 60-49990, No. 60-83882,
Nos. 60-109894, 61-277484, 61-293886, 62-19483, 62
-198493, 63-49478 and 63-1
No. 15780, No. 63-203896, No. 63-27
No.4583, No.63-280681, No.63-260
No. 477, JP-A-1-9776 and JP-A-1-24784.
Nos. 1-40371, 3133686, 6
JP-A-234268 and JP-A-7-125411 disclose a number of techniques for improving the fixability of an ink dye by adding a cationic mordant.

However, most of the materials disclosed in the prior art tend to form aggregates when mixed with inorganic fine particles having an anionic surface, such as silica, so that a good coating solution cannot be prepared or a coating film cannot be formed. There was a problem that the glossiness of the surface was significantly reduced.

In order to improve this point, the present applicant has filed a patent application in a previous application (Japanese Patent Application No. 9-23808) for using a water-soluble cationic polymer having an average molecular weight of 50,000 or less. However, this has made it possible to obtain sufficiently excellent water resistance and gloss.

However, as a result of the subsequent examination, it has been found that if the images are superimposed in a relatively short time after being printed by an ink jet printer or stored in a clear file or the like, the image tends to gradually spread over time, and further improvement is desired. I was It has been found that the bleeding due to aging depends on the type of the dye used in the ink and the content of the water-soluble high-boiling organic solvent, but also on the fixing degree of the dye on the recording paper.

As a result of intensive studies on this point, the present inventors have found that the bleeding of an image after printing depends on the structure of the cationic polymer. In particular, it has been found that when the cationic component is a cationic monomer bonded to a mother nucleus such as styrene, the bleeding resistance is improved. On the other hand, when this kind of cationic polymer is used, light resistance is liable to decrease. It also turned out to have drawbacks.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an ink jet recording having a void layer comprising inorganic fine particles and a hydrophilic binder. An object of the present invention is to provide an ink jet recording sheet in which the bleeding of an image after printing is improved without adversely affecting light fastness while maintaining high gloss and high porosity of the sheet.

[0015]

Means for Solving the Problems The above problems are: A hydrophilic binder, inorganic fine particles having an average primary particle diameter of 30 nm or less, and a general formula (1)
An ink-jet recording paper comprising an ink absorbing layer containing cationic composite particles composed of a water-soluble cationic polymer having an average molecular weight of 100,000 or less,

[0016]

Embedded image In the formula, R and R ′ each have a hydrogen atom or a carbon atom number of 1 to 1.
4 represents an alkyl group represented by R ₁ , R ₂ , R ₃ , R ₁ ′, R
₂ ′ and R ₃ ′ each represent an alkyl group, and A and J each represent a divalent linking group. X ₁ ^- and _{X 2} ^- represents an anion group. Q represents a repeating unit derived from a monomer having an ethylenically unsaturated group. Q includes the case where two or more monomers are copolymerized. x is 10 to 95 mol%, y
Is 5 to 90 mol%, and z is 0 to 60 mol%. m is 1
Represents a positive number from to 6. Achieved by

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
Examples of the inorganic fine particles having an average primary particle size of 30 nm or less used in the present invention include light calcium carbonate,
Heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc hydroxide, zinc sulfide, zinc carbonate,
Hydrotalcite, aluminum silicate, diatomaceous earth,
Examples thereof include white inorganic pigments such as calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone, zeolite, and magnesium hydroxide.

In the present invention, silica or pseudo-boehmite is preferable, particularly from the viewpoint that the film has high transparency and fine voids can be formed, and silica synthesized by a gas phase method is most preferably used. Aerosil series manufactured by Nippon Aerosil Co., Ltd., for example, is commercially available as fine-particle silica synthesized by a gas phase method.

Here, the average particle size of the inorganic fine particles is obtained as a simple average value (number average) by observing with an electron microscope the particle size of 100 arbitrary particles. Here, each particle size is represented by a diameter assuming a circle equal to the projected area.

In the present invention, the inorganic fine particles are used by forming cationic composite particles together with a cationic polymer represented by the general formula (1) having an average molecular weight of 50,000 or less.

The method of forming the composite particles is to mix an aqueous solution containing a water-soluble cationic polymer and a dispersion containing inorganic fine particles having an anionic surface to eliminate aggregates generated at that time. This mixture is obtained by dispersion.

By performing this dispersion treatment, a dispersion liquid of cation-converted inorganic fine particles can be obtained. As the dispersion treatment method, various kinds of conventionally known dispersers such as a high-speed rotation disperser, a medium stirring type disperser (such as a ball mill and a sand mill), an ultrasonic disperser, a colloid mill disperser, a roll mill disperser, and a high-pressure disperser are used. Although it can be used, in the present invention, an ultrasonic disperser or a high-pressure disperser is preferably used from the viewpoint of efficiently dispersing the formed lumpy fine particles.

An ultrasonic disperser is usually used for dispersing energy by concentrating energy on a solid-liquid interface by irradiating an ultrasonic wave of 20 to 25 KHz, and is dispersed very efficiently. Is not very appropriate if you need to adjust.

On the other hand, the high-pressure disperser is provided with one or two homogenous valves at the outlet of a high-pressure pump having three or five pistons, the gap of which can be adjusted by screw or hydraulic pressure. The flow of the liquid medium sent by the high-pressure pump is restricted by the homogenous valve and pressure is applied. At the moment when the liquid medium passes through the homogenous valve, fine lump material is crushed.

This method is particularly preferable when a large amount of liquid is produced because a large amount of liquid can be dispersed continuously. The pressure applied to the homogeneous valve is approximately 50-1000
Kg / cm ² , and the dispersion can be performed in one pass or can be repeated many times.

In preparing the cationic dispersion, it can be adjusted by adding various additives. For example, various nonionic or cationic surfactants (anionic surfactants are not preferable because they form aggregates), antifoaming agents, nonionic hydrophilic polymers (polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide) , Polyacrylamide, various sugars, gelatin, pullulan, etc.), nonionic or cationic latex dispersion, water-miscible organic solvents (ethyl acetate, methanol, ethanol, isopropanol, n-propanol, acetone, etc.), inorganic salts, pH An adjusting agent and the like can be appropriately used as needed.

In particular, a water-miscible organic solvent is preferable because formation of fine lumps when inorganic fine particles and a cationic polymer are mixed is suppressed. Such a water-miscible organic solvent is present in the dispersion in an amount of 0.1 to 20% by weight, particularly preferably 0.1 to 20% by weight.
It is used in an amount of 5 to 10% by weight.

The pH at the time of preparing the cationic dispersion can vary widely depending on the type of inorganic fine particles, the type of cationic polymer, various additives and the like.
To 8, and particularly preferably 2 to 7. The above dispersion can be used in combination of two or more kinds.

The cationic polymer used in the present invention is represented by the general formula (1). In the general formula (1),
R and R 'are a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, preferably a hydrogen atom or a methyl group. R ₁ , R ₂ , R ₃ , R ₁ ′, R ₂ ′ and R ₃ ′
Each represents an alkyl group, preferably a methyl group or an ethyl group. Each of the alkyl groups may have a substituent. A and J each represent a divalent linking group, where A is a mere bond, -CONH-, or -COO.
-Is preferred. J is preferably a simple bond or a -CON (R ")-group (R" represents a hydrogen atom or an alkyl group which may have a substituent). X ₁ ^- and X ₂ ^- represent anion groups (halogen ion, methyl sulfate ion, p-toluenesulfonic acid ion and the like). Q represents a repeating unit derived from a monomer having an ethylenically unsaturated group. Specific examples of the monomer of Q include, for example, styrene, butadiene, methyl methacrylate, ethyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, hydroxyethyl methacrylate, vinyl acetate, vinyl ether, acrylamide, N-methylacrylamide , N-vinylimidazole, 4-vinylpyridine, N-vinylpyrrolidone, vinyl chloride and the like. Q includes the case where two or more monomers are copolymerized. x is 10 to 95 mol%, preferably 20 to 80 mol%, and y is 5 to 90 mol%, preferably 10 to 60 mol%.
And z is 0 to 60 mol%, preferably 0 to 4 mol%.
0 mol%.

Next, specific examples of the cationic polymer composition represented by the general formula (1) will be shown. In the general formula (1),

[0031]

Embedded image And a repeating unit represented by

[0032]

Embedded image The repeating unit represented by may be a mixture of two or more repeating units.

[0033]

Embedded image

[0034]

Embedded image

[0035]

Embedded image

[0036]

Embedded image

[0037]

Embedded image

The cationic polymer represented by the general formula (1) needs to have a number average molecular weight of 100,000 or less. Here, the number average molecular weight is a value converted into a polystyrene value determined by gel permeation chromatography. When the number average molecular weight exceeds 100,000,
When an aqueous solution of a cationic polymer is added to a dispersion containing inorganic fine particles whose surface is anionic, agglomerates are severely generated, and a large number of coarse particles are hard to be formed into a uniform dispersion even after the subsequent dispersion treatment. To make a uniform dispersion. When such a composite fine particle dispersion liquid comprising a cationic polymer and inorganic fine particles is used for glossy paper for inkjet, high gloss cannot be obtained. Preferably it is 50,000 or less. The lower limit of the number average molecular weight is generally 2,000 or more from the viewpoint of the water resistance of the dye.
000 or more is preferable.

The ratio of the inorganic fine particles to the cationic polymer can vary depending on the type and particle size of the inorganic fine particles, or the type and average molecular weight of the cationic polymer, but is generally about 1:
It is 0.01 to 1: 1. The cationic polymer used in the present invention is described in the prior art (JP-A-8-14249).
6), the prior art differs from the present application in that separate water-soluble polymers having two different types of repeating units are used in combination. Further, in the prior art, since the ink absorbing layer is substantially a so-called swelling type ink absorbing layer, it is difficult to obtain a good ink absorbing speed, and these points are clearly different from the present application.

As the hydrophilic binder used for the recording paper of the present invention, various conventionally known hydrophilic binders are used. When the hydrophilic binder is mixed with the cationic composite fine particles of the present invention, they exhibit an aggregation and a remarkable thickening action. No hydrophilic binders are preferred. Examples of such a hydrophilic binder include gelatin (preferably acid-treated gelatin), polyvinylpyrrolidone (preferably having an average molecular weight of about 200,000 or more), pullulan, polyvinyl alcohol or a derivative thereof, and polyethylene glycol (average molecular weight of 100,000 or more). ), Hydroxyethylcellulose, dextran, dextrin, and water-soluble polyvinyl butyral. These hydrophilic binders may be used alone or in combination of two or more. Particularly preferred hydrophilic binders are polyvinyl alcohol or cationically modified polyvinyl alcohol.

The polyvinyl alcohol preferably used in the present invention preferably has an average degree of polymerization of 300 to 4,000, and is particularly preferable because the film having an average molecular weight of 1,000 or more has good brittleness.
The saponification degree of polyvinyl alcohol is 70 to 100.
%, Particularly preferably 80 to 100%.

Further, the cation-modified polyvinyl alcohol can be obtained by saponifying a copolymer of an ethylenically unsaturated monomer having a cationic group and vinyl acetate. Examples of the ethylenically unsaturated monomer having a cationic group include trimethyl- (2-acrylamide-2,
2-dimethylethyl) ammonium chloride, trimethyl- (3-acrylamido-3,3-dimethylpropyl) ammonium chloride, N-vinylimidazole, N-vinyl-2-methylimidazole, N- (3-
Dimethylaminopropyl) methacrylamide, hydroxylethyltrimethylammonium chloride, trimethyl-(-methacrylamidopropyl) ammonium chloride, N- (1,1-dimethyl-3-dimethylaminopropyl) acrylamide and the like.

The proportion of the cation-modified group-containing monomer in the cation-modified polyvinyl alcohol is 0.1 to 10 mol%, preferably 0.2 to 5 mol%, based on vinyl acetate. The polymerization degree of the cation-modified polyvinyl alcohol is usually 500 to 4000, preferably 1000 to 4000. The degree of saponification of the cation-modified polyvinyl alcohol is usually 60 to 100 mol%, preferably 70 to 9 mol%.
9 mol%.

Amount of the above-mentioned hydrophilic binder A relatively small amount is used based on the inorganic fine particles so that the ink-absorbing layer becomes a void layer, so that the film is formed stably and the adhesion to the support can be sufficiently maintained. It is preferable to use as little as possible. Generally, the weight ratio is about 1/3 to 1/10, especially 1/4 to 1/8 with respect to the inorganic fine particles.

In the ink jet recording paper of the present invention, the hydrophilic binder is preferably hardened with a hardener in order to obtain a high gloss and a high porosity without deteriorating the brittleness of the film.

The hardener is generally a compound having a group capable of reacting with the hydrophilic binder or a compound which promotes a reaction between different groups of the hydrophilic binder. Is appropriately selected and used according to the conditions.

Specific examples of the hardener include, for example, epoxy hardeners (diglycidyl ethyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidyl cyclohexane, N , N-diglycidyl-4-glycidyloxyaniline, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, etc., aldehyde hardeners (formaldehyde, glyoxal, etc.), active halogen hardeners (2,4-dichloro-4-) Hydroxy-1,3,5-s-triazine, etc.), active vinyl compounds (1,3,5-trisacryloyl-hexahydro-)
s-triazine, bisvinylsulfonyl methyl ether, etc.), boric acid and its salts, borax, aluminum alum and the like.

When polyvinyl alcohol and / or cation-modified polyvinyl alcohol is used as a particularly preferred hydrophilic binder, boric acid and its salts,
It is preferable to use a hardening agent selected from epoxy hardeners.

Most preferred are hardeners selected from boric acid and its salts. In the present invention, the boric acid or a salt thereof refers to an oxyacid having a boron atom as a central atom and a salt thereof, specifically, orthoboric acid, diboric acid,
Includes metaboric, tetraboric, pentaboric, and octanoic acids and their salts.

The amount of the hardener used varies depending on the type of the hydrophilic binder, the type of the hardener, the type of the inorganic fine particles, the ratio to the hydrophilic binder, and the like. Preferably 10 to 40
0 mg.

The above-mentioned hardener may be added to the coating liquid for forming the void layer and / or to the coating liquid for forming another layer adjacent to the void layer when the coating liquid for forming the void layer is applied. Alternatively, on a support on which a coating solution containing a hardener has been applied in advance, a coating solution for forming the void layer may be applied, or a hardener-free coating solution for forming a void layer may be further applied. The hardener can be supplied to the gap layer by overcoating the hardener solution after coating and drying, but preferably, from the viewpoint of manufacturing efficiency, the coating solution for forming the gap layer or the adjacent layer can be used. It is preferable to add a hardening agent to the coating solution and supply the hardening agent at the same time as forming the void layer.

The ink absorbing layer of the ink jet recording paper of the present invention and other layers provided as necessary include:
Various additives other than those described above can be added.
For example, organic latex fine particles such as polystyrene, polyacrylates, polymethacrylates, polyacrylamides, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, or a copolymer thereof, a urea resin, or a melamine resin. , Liquid paraffin, dioctyl phthalate, tricresyl phosphate, oil droplet fine particles such as silicone oil, various cationic or nonionic surfactants, JP-A-57-74193, JP-A-57-87988 and JP-A-62-2614.
No. 76, JP-A-57-741.
Nos. 92, 57-87989 and 60-7278
No. 5, JP-A-61-146591, JP-A No. 1-9
No. 5091 and JP-A-3-13376, anti-fading agents described in JP-A-59-42993,
JP-A-59-52689, JP-A-62-280069, JP-A-61-242871, and JP-A-4-21.
No. 9266, a fluorescent whitening agent, sulfuric acid,
Contains various known additives such as pH adjusters such as phosphoric acid, citric acid, sodium hydroxide, potassium hydroxide, and potassium carbonate, defoamers, preservatives, thickeners, antistatic agents, matting agents, and the like. Can also.

The void volume of the ink absorbing layer of the ink jet recording paper of the present invention is approximately 20 to 40 ml / m ² ,
The porosity of this layer is approximately 0.5 to 0.8. The ink absorbing layer may be composed of two or more layers. In this case, the constitutions of the ink absorbing layers may be the same or different. The film surface pH of the ink absorbing layer of the recording paper of the present invention is generally in the range of 3 to 6.

In the present invention, as a support for the ink jet recording paper, a paper support, a plastic support, a composite support, etc., which are conventionally known as the ink jet recording paper, can be used as appropriate, but in order to obtain a clear image at a higher density. It is preferable to use a hydrophobic support that does not penetrate the ink liquid into the support.

As the hydrophobic support, a transparent or opaque plastic resin film support and a paper support in which the surface of paper is laminated with polyethylene are preferably used.

The transparent support is made of, for example, a material such as polyester resin, diacetate resin, triatesate resin, acrylic resin, polycarbonate resin, polyvinyl chloride resin, polyimide resin, cellophane, and celluloid. Film and the like.
Those having the property of resisting radiant heat when used as HP are preferable, and polyethylene terephthalate is particularly preferable. The thickness of such a transparent support is about 10 to
200 μm is preferred. It is preferable to provide a known undercoat layer on the ink receiving layer side and the back layer side of the transparent support from the viewpoint of the adhesion between the ink receiving layer and the back layer and the support.

As the support used when it is not necessary to be transparent, for example, resin-coated paper (so-called RC paper) having a polyolefin resin-coated layer obtained by adding a white pigment or the like to at least one of the base paper, polyethylene terephthalate A so-called white pet obtained by adding a white pigment to the ink is preferred.

Prior to the application of the ink-receiving layer, for the purpose of increasing the adhesive strength between the support and the ink-receiving layer,
The support is preferably subjected to a corona discharge treatment, an undercoating treatment, or the like. Furthermore, the recording sheet of the present invention is not necessarily colorless, and may be a colored recording sheet.

In the ink jet recording paper of the present invention, it is particularly preferable to use a paper support in which both sides of the base paper support are laminated with polyethylene, since the recorded image is close to the photographic quality and a high quality image can be obtained at low cost. preferable.
Such a paper support laminated with polyethylene is described below.

The base paper used for the paper support is made from wood pulp as a main raw material, and if necessary, in addition to wood pulp, using synthetic pulp such as polypropylene or synthetic fiber such as nylon or polyester. As wood pulp, LBKP, LBSP, NBKP, NBSP, LD
Any of P, NDP, LUKP, and NUKP can be used, but LBKP, NBSP, and LBS containing a large amount of short fibers
It is preferable to use more P, NDP, and LDP.
However, the ratio of LBSP and / or LDP is 10% by weight.
At least 70% by weight is preferred.

As the pulp, a chemical pulp containing less impurities (sulfate pulp or sulfite pulp) is preferably used, and pulp having improved whiteness by performing a bleaching treatment is also useful.

In the base paper, sizing agents such as higher fatty acids and alkyl ketene dimers, white pigments such as calcium carbonate, talc and titanium oxide, paper strength agents such as starch, polyacrylamide and polyvinyl alcohol, fluorescent whitening agents, Water retention agents such as polyethylene glycols, dispersants, and softening agents such as quaternary ammonium can be appropriately added.

The freeness of the pulp used for papermaking is preferably 200 to 500 ml according to the CSF standard, and the fiber length after beating is 24 mesh residual weight% and 42 mesh residual weight specified in JIS-P-8207. 30% by weight
~ 70% is preferred. In addition, it is preferable that the weight% of the 4 mesh residue is 20% by weight or less. Base paper weight is 3
The amount is preferably from 0 to 250 g, particularly preferably from 50 to 200 g. The thickness of the base paper is preferably from 40 to 250 μm.

The base paper may be calendered at the papermaking stage or after the papermaking to provide high smoothness. The base paper density is generally 0.7 to 1.2 g / m ² (JIS-P-8118). Further, the rigidity of the base paper is preferably from 20 to 200 g under the conditions specified in JIS-P-8143.

A surface sizing agent may be applied to the surface of the base paper. As the surface sizing agent, the same sizing agent as can be added to the base paper can be used. Base paper pH is JIS-
When measured by the hot water extraction method specified in P-8113, it is preferably 5 to 9.

The polyethylene covering the front and back surfaces of the base paper is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but other LLDPE, polypropylene and the like can also be partially used.

In particular, the polyethylene layer on the ink receiving layer side is preferably a layer obtained by adding rutile or anatase type titanium oxide to polyethylene to improve opacity and whiteness as widely used in photographic printing paper. The content of titanium oxide is approximately 3 to 20% by weight based on polyethylene,
Preferably it is 4 to 13% by weight.

The polyethylene-coated paper may be used as a glossy paper, or may be subjected to a so-called embossing process when the polyethylene is melt-extruded onto the base paper surface to carry out a matting process or a silk-like process which can be obtained with ordinary photographic printing paper. Those having a surface can also be used in the present invention.

The amount of polyethylene used on the front and back of the base paper is selected so as to optimize the curl at low and high humidity after the ink receiving layer and the back layer are provided. Is in the range of 20 to 40 μm, and the back layer side is in the range of 10 to 30 μm.

Further, the polyethylene-coated paper support preferably has the following characteristics. Tensile strength: The strength specified in JIS-P-8113 is preferably 2 to 30 kg in the vertical direction and 1 to 20 kg in the horizontal direction. The tear strength is preferably 10 to 200 g in the vertical direction and 20 to 200 g in the horizontal direction according to the method defined in JIS-P-8116. Compression elasticity ≧ 103 Kgf / cm ² Surface Beck smoothness: 20 seconds or more is preferable as a glossy surface under the conditions specified in JIS-P-8119, but may be less than this for so-called molded products. Opacity: Under the measurement conditions of linear light incidence / diffuse light transmission conditions, the transmittance for visible light rays is preferably 20% or less, particularly preferably 15% or less.

The method of applying various hydrophilic layers, which are appropriately provided as necessary, such as a void layer and an undercoat layer, of the recording paper of the present invention to a support can be appropriately selected from known methods. A preferred method is obtained by applying a coating solution constituting each layer on a support and drying it. In this case, 2
More than one layer can be coated simultaneously, and in particular, simultaneous coating is preferable, in which all the hydrophilic binder layers need only be coated once.

As a coating method, a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a curtain coating method or an extrusion coating method using a hopper described in US Pat. No. 2,681,294 is preferably used.

When recording an image using the ink jet recording paper of the present invention, a recording method using an aqueous ink is preferably used. The aqueous ink referred to in the present invention is a recording liquid comprising the following colorant, liquid medium, and other additives. As the colorant, a water-soluble dye or a water-dispersible pigment such as a direct dye, an acid dye, a basic dye, a reactive dye, or a food colorant known by inkjet can be used.

Examples of the solvent for the aqueous ink include water and various water-soluble organic solvents, for example, alcohols such as methyl alcohol, isopropyl alcohol, n-butyl alcohol, tert-butyl alcohol and isobutyl alcohol; dimethylformamide, dimethylacetamide and the like. Amides; ketones or ketone alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol, propylene glycol, butylene glycol, triethylene glycol; 1,2,6
Polyhydric alcohols such as hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol, glycerin and triethanolamine; polyhydric alcohols such as ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether and triethylene glycol monobutyl ether; And lower alkyl ethers.

Among these many water-soluble organic solvents,
Preferred are polyhydric alcohols such as diethylene glycol, triethanolamine and glycerin, and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monobutyl ether.

Other additives for the aqueous ink include, for example, a pH adjuster, a metal sequestering agent, an anti-binder, a viscosity adjuster,
Surface tension adjusters, wetting agents, surfactants, rust inhibitors, and the like. The aqueous ink liquid is 25 to 60 dy at 20 ° C. in order to improve the wettability on the recording paper.
It preferably has a surface tension in the range of n / cm, preferably 30 to 50 dyn / cm.

[0077]

The present invention will be described below with reference to examples of the present invention.
The present invention is not limited to these examples. In addition,
In Examples, "%" indicates absolute dry weight% unless otherwise specified.

Example 1 The average particle size of the primary particles dispersed uniformly in advance is about 0.5.
012 μm fumed silica (manufactured by Nippon Aerosil Co., Ltd .:
A200) (4500 ml) of an 18% aqueous solution A1 (pH = 2.5, containing 3% by weight of ethanol), 12% by weight of exemplified cationic polymer P-1 (average molecular weight = about 25,000)
To 1000 ml of an aqueous solution C1 (pH = 2.5, containing 0.2 g of an antifoaming agent SN381 manufactured by Sannobuco) containing 3% by weight of n-propanol and 1% by weight of ethanol was added with stirring at room temperature. Next, 400 ml of a 1: 1 mixed aqueous solution of boric acid and borax (both boric acid and borax each containing 5% by weight) was gradually added with stirring.
Then, a high pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd.
g / cm ² , uniform and almost transparent dispersion liquid B
1 was obtained.

Next, the following four kinds of coating liquids were prepared using the dispersion B1. Preparation of coating solution for first layer (amount per liter of coating solution) Silica dispersion B1 620 ml Fluorescent whitening agent dispersion (described below) 30 ml Titanium oxide dispersion (described below) 20 ml Polyvinyl alcohol (Kuraray PVA203) 10% Aqueous solution 5 ml Polyvinyl alcohol (Pura235, Kuraray) 5% aqueous solution 270 ml Latex dispersion (AE803, Showa Kogaku Kogyo Co., Ltd.) 30 ml Pure water (total volume 1000 ml)

Coating solution for second layer (amount per liter of coating solution) Silica dispersion B1 640 ml Fluorescent whitening agent dispersion (described below) 25 ml Polyvinyl alcohol (PVA203 manufactured by Kuraray Co., Ltd.) 10% aqueous solution 5 ml Polyvinyl alcohol (Kuraray Co., Ltd.) PVA 235) 5% aqueous solution 270 ml Latex dispersion (AE803 manufactured by Showa Kogyo Kogyo Co., Ltd.) 30 ml Pure water (total volume 1000 ml)

Coating solution for third layer (amount per liter of coating solution) Silica dispersion B1 650 ml Fluorescent whitening agent dispersion (described below) 20 ml Polyvinyl alcohol (PVA203 manufactured by Kuraray Co., Ltd.) 10% aqueous solution 5 ml Polyvinyl alcohol (Kuraray Co., Ltd.) PVA 235) 5% aqueous solution 270 ml Latex dispersion (AE803, Showa Kogaku Kogyo KK) 15 ml Pure water (total volume 1000 ml)

Coating solution for fourth layer (amount per liter of coating solution) Silica dispersion B1 610 ml Polyvinyl alcohol (PVA203 manufactured by Kuraray) 10% aqueous solution 5 ml Polyvinyl alcohol (PVA235 manufactured by Kuraray) 5% aqueous solution 270 ml Surfactant (Saponin) 10% aqueous solution 10 ml Silicon dispersion (BY-22-839, manufactured by Dow Corning Toray Silicone Co., Ltd.) 20 ml Pure water (total amount is finished to 1000 ml)

Fluorescent Whitening Agent Dispersion: An oil-soluble fluorescent whitening agent (UVITEX-OB, manufactured by Ciba-Geigy Co., Ltd.) was added to 100 ml of a 3% acid-treated gelatin aqueous solution (containing 4 g of saponin and 2 g of cationic polymer P-9). ) A solution prepared by heating and dissolving 0.6 g and 12 g of diisodecyl phthalate in 25 ml of ethyl acetate was added, and emulsified and dispersed by an ultrasonic homogenizer.
Make up to 140ml with pure water. Titanium oxide dispersion: Titanium oxide manufactured by Ishihara Sangyo (W10)
Is 40% by weight. The viscosity of each of the above coating liquids is 30 to 40 cp at 40 ° C.
It had a viscosity of 10,000 to 20,000 at 5 ° C.

The coating solution obtained as described above was
0 g / m ² base paper coated on both sides with polyethylene (240 μm thick, about 35 μm thick polyethylene layer on the recording side containing 6% by weight of anatase type titanium dioxide, back side about 30 μm thick The first layer (50 μm) and the second layer (50 μm) on the recording surface side (75 ° gloss of the support is 32% and gelatin is coated as a subbing layer of about 0.1 g / m ² ) on the recording layer side. 50 μm), third layer (50 μm)
m) and the fourth layer (50 μm). The figures in parentheses indicate the respective wet film thicknesses, and the first layer to
The fourth layer was applied simultaneously.

Each coating solution was applied at 40 ° C. with a four-layer slide hopper, immediately after coating, cooled in a cooling zone maintained at 0 ° C. for 20 seconds, and then blown with a wind of 20 to 30 ° C. for 60 seconds. , 45 ° C for 60 seconds, 50 ° C for 6 seconds
The recording paper-1 of the present invention was obtained by successively drying for 0 seconds. The recording paper obtained was then stored at 35 ° C. for 2 days.

Next, in recording paper-1, the cationic polymer was changed as shown in Table 1 to obtain dispersions B2 to B1.
No. 0 was prepared in the same manner as the dispersion B1, and using this, recording paper-2 to 10 were prepared in the same manner as the recording paper-1.

The following items were evaluated for the obtained ink jet recording paper. (1) Image bleeding: M, C, and K lines were printed with a width of about 0.3 mm using an ink jet printer PM750C manufactured by Seiko Epson Corporation, and after 10 minutes from printing, they were stored in a clear file for 30 days. . After the storage, the line width of each line was measured with a microdensitometer to determine the spread ratio of the line width (the ratio of the line width after storage to the original line width).

(2) Light fastness: Using the ink jet printer used in (1), a magenta image was formed on each recording sheet, and this was irradiated with light for 200 hours using a xenon fade meter to maintain the density after light irradiation. The rate was checked. Table 1 shows the obtained results.

(3) Glossiness: A 75-degree specular glossiness was measured with a goniophotometer (VGS-1001DP) manufactured by Nippon Denshoku Industries Co., Ltd.

[0090]

[Table 1]

[0091]

Embedded image

From the results in Table 1, it can be seen that the recording papers 1 to 1 of the present invention were used.
It can be seen that Sample No. 6 showed little bleeding even when stored in a clear file after printing, and exhibited good light fastness. On the other hand, since the average molecular weight of the recording paper-7 exceeded 100,000, the glossiness was lowered, and the recording paper using the comparative cationic polymer RP1 was used.
No. 8 has good light fastness but poor image bleeding. The recording papers -9 and 10 using the comparative cationic polymers RP2 and RP3 had good image bleeding, but were inferior in light resistance to the present invention.

[0093]

According to the present invention, it is possible to obtain an ink-jet recording paper in which bleeding of an image is improved even when stored in a high humidity state after printing or when stored by overlapping.

Claims (1)

[Claims] 1. A hydrophilic binder, an inorganic fine particle having an average primary particle size of 30 nm or less, and a water-soluble cationic polymer having an average molecular weight of 100,000 or less represented by the following general formula (1) on a support. An ink jet recording sheet having an ink absorbing layer containing cationic composite particles composed of: Embedded image In the formula, R and R ′ each have a hydrogen atom or a carbon atom number of 1 to 1.
4 represents an alkyl group represented by R ₁ , R ₂ , R ₃ , R ₁ ′, R
₂ ′ and R ₃ ′ each represent an alkyl group, and A and J each represent a divalent linking group. X ₁ ^- and _{X 2} ^- represents an anion group. Q represents a repeating unit derived from a monomer having an ethylenically unsaturated group. Q includes the case where two or more monomers are copolymerized. x is 10 to 95 mol%, y
Is 5 to 90 mol%, and z is 0 to 60 mol%. m is 1
Represents a positive number from to 6.