JP2001096911A - Ink jet recording paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording paper, which is excellent in ink- absorbing property. SOLUTION: This ink jet recording paper is constituted by providing a coloring matter-receiving layer on a supporting body. In such an ink jet recording paper, the coloring matter-receiving layer comprises vapor phase silica, colloidal silica and a water-soluble polymer.

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 (hereinafter, simply referred to as a recording sheet), and more particularly to an ink jet recording sheet having excellent ink absorbency.

[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 with the above recording methods, improvements have been made in both ink and device aspects, and are now rapidly spreading to various fields such as various printers, facsimile machines and computer terminals. ing.

[0003] The recording paper used for the ink jet recording has a high density of print dots, a bright and vivid color tone, and the ink is quickly absorbed and the ink flows out or bleeds even when the print dots overlap. It is required that the print dots do not smear, the diffusion of the print dots in the horizontal direction is not unnecessarily large, and 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, The colors tend to bleed in the boundary area of, and the image quality tends to be greatly reduced. In addition, when the ink absorption capacity is small, the output ink overflows and unevenness occurs in the printing portion. Therefore, it is necessary that the ink jet recording paper has high ink absorbency.

In order to solve these problems, an ink absorbing layer having a void structure composed of inorganic fine particles and a binder polymer has been proposed. As these inorganic fine particles,
Until now, colloidal silica has been widely used and is advantageous in terms of cost.However, if only colloidal silica is used as the inorganic fine particles, it is not possible to provide a sufficient porosity to the ink-absorbing layer. There was a drawback that the properties were poor.

[0006]

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 sheet having excellent ink absorbability.

[0007]

The above object of the present invention is achieved by the following constitution. (1) An ink jet recording sheet comprising a support provided with a color material receiving layer, wherein the color material receiving layer is formed from fumed silica, colloidal silica, and a water-soluble polymer. Paper. (2) The ink jet recording paper according to the above (1), wherein the colloidal silica is a beaded colloidal silica. (3) The weight ratio of fumed silica to colloidal silica is 1:
The inkjet recording paper according to the above (1) or (2), wherein the ratio is 20 to 20: 1. (4) The inkjet recording paper according to any one of (1) to (3), wherein the water-soluble polymer is polyvinyl alcohol. (5) The ink jet recording paper according to any one of the above (1) to (4), wherein the colorant receiving layer contains boric acid and / or borate. (6) The ink jet recording paper according to any one of the above (1) to (3), wherein the colorant receiving layer contains a cationic polymer. (7) The ink jet recording paper as described in any one of (1) to (6) above, wherein the support is a paper whose surface is coated with a polyolefin resin.

Hereinafter, the present invention will be described in detail. First, the fumed silica, colloidal silica, and water-soluble polymer used in the present invention will be described. Vapor phase silica is a synthetic silica compound composed mainly of silicon dioxide, ultrafine silica synthesized by the so-called dry method or gas phase method made by burning silicon tetrachloride with hydrogen and oxygen. It is. The primary particle diameter of fumed silica is 5 to 50.
nm. Examples of such fumed silica include AEROSIL series manufactured by Nippon Aerosil Co., Ltd. and Leoloseal series manufactured by Tokuyama Corporation.

Colloidal silica is obtained by dispersing silicon dioxide in water in a colloidal state and has a primary particle diameter of 5%.
It is spherical at about 100 nm. Examples of such colloidal silica include Snowtex series manufactured by Nissan Chemical Industries, Cataloid-S series manufactured by Catalysis Chemical Industry Co., Ltd., and Lebasil series manufactured by Bayer Corporation.

The rosary-shaped colloidal silica is formed by connecting a plurality of spherical colloidal silicas to form a rosary. Beaded colloidal silica (beaded colloidal silica) is obtained by bonding spherical primary particles of colloidal silica with divalent or higher metal ions. Ca ²⁺ , M
g ²⁺ , Ba ²⁺ , Al ²⁺ , Ti ²⁺ and the like.

The primary particle diameter of the colloidal silica from which the beads are connected is preferably from 5 to 100 nm, and preferably from 7 to 40 nm in order to increase the porosity. The beaded colloidal silica preferably has a length of 30 to 500 nm. Further, the beaded colloidal silica may be one in which colloidal silica and other inorganic particles are connected in a beaded shape. Other inorganic particles used here include:
For example, alumina, ceria, titania and the like can be mentioned.
Examples of the beaded colloidal silica include a Snowtex-PS series and a Snowtex-UP series of Nissan Chemical Industries, Ltd.

Examples of the water-soluble polymer include polyvinyl alcohol, gelatin, polyethylene oxide,
Polyvinylpyrrolidone, dextran, dextrin,
Carrageenan (κ, ι, λ, etc.), agar, pullulan, water-soluble polyvinyl butyral, hydroxyethylcellulose, carboxymethylcellulose and the like can be mentioned, and the water-soluble polymer used in the present invention is preferably polyvinyl alcohol.

The polyvinyl alcohol includes, in addition to ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, cation-modified polyvinyl alcohol having a cation-modified terminal, anion-modified polyvinyl alcohol having an anionic group, and the like. And nonionic modified polyvinyl alcohol.

The polyvinyl alcohol obtained by hydrolyzing vinyl acetate preferably has an average degree of polymerization of 1000 or more, and particularly preferably has an average degree of polymerization of 1500 to 5000. If the average degree of polymerization is low, the film-forming properties are poor and cracks may occur. The saponification degree is preferably from 70 to 100%, particularly preferably from 80 to 99.5%.

As the cation-modified polyvinyl alcohol, for example, a tertiary amino group or a quaternary ammonium group as described in JP-A-61-10483 can be prepared by adding a main chain or a side chain of polyvinyl alcohol. And polyvinyl alcohol contained therein. These cation-modified polyvinyl alcohols are obtained, for example, 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-acrylamido-2,2-dimethylethyl) ammonium chloride and trimethyl- (3-acrylamido-3,3-dimethylpropyl). ) Ammonium chloride, N-vinylimidazole, N-vinyl-2-methylimidazole, N
-(3-dimethylaminopropyl) methacrylamide,
Examples include hydroxylethyl trimethylammonium chloride, trimethyl- (methacrylamidopropyl) ammonium chloride, and N- (1,1-dimethyl-3-dimethylaminopropyl) acrylamide.

The ratio of the monomer having a cationic modifying group in the copolymer of an ethylenically unsaturated monomer having a cationic group (monomer having a cationic modifying group) and vinyl acetate is 0 to vinyl acetate. Is preferably from 0.1 to 10 mol%, more preferably from 0.2 to 5 mol%.

The anion-modified polyvinyl alcohol is described in, for example, polyvinyl alcohol having an anionic group as described in JP-A-1-2060888, JP-A-61-237681 and JP-A-63-307979. Copolymer of vinyl alcohol and a vinyl compound having a water-soluble group as described in JP-A-7-2852
No. 65, a modified polyvinyl alcohol having a water-soluble group.

Examples of the nonionic modified polyvinyl alcohol include polyvinyl alcohol derivatives having a polyalkylene oxide group added to a part of vinyl alcohol as described in JP-A-7-9758, and JP-A-8-25795. Examples thereof include a block copolymer of a vinyl compound having a hydrophobic group and vinyl alcohol as described in the gazette. As the polyvinyl alcohol, two or more kinds of polyvinyl alcohols having different degrees of polymerization and types of modification can be used in combination.

In the ink jet recording paper of the present invention, it is preferable to use a cationic polymer in order to improve water resistance and bleeding resistance after recording. The cationic polymer can be arbitrarily selected from the known cationic polymers for ink jet recording paper.

The cationic polymer used in the present invention is preferably a polymer having a quaternary ammonium group, and more preferably a homopolymer of a monomer having a quaternary ammonium group or another copolymerizable 1 or 2 monomer. It is a copolymer with the above monomers. It is particularly preferred that the weight average molecular weight is from 2,000 to 100,000.
Examples of the monomer having a quaternary ammonium base include, for example, the following examples.

[0022]

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[0023]

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Examples of the monomer copolymerizable with the monomer having a quaternary ammonium base include a compound having an ethylenically unsaturated group, and examples thereof include the following specific examples.

[0025]

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In particular, when the cationic polymer having a quaternary ammonium base is a copolymer, the ratio of the cationic monomer used is preferably at least 10 mol%, more preferably at least 20 mol%, and particularly preferably. 3
0 mol% or more. The monomer having a quaternary ammonium base may be used alone or in combination of two or more. Hereinafter, specific examples of the cationic polymer of the present invention will be described, but the present invention is not limited thereto.

[0027]

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[0028]

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[0029]

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[0030]

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The cationic polymer having a quaternary ammonium group has generally high water solubility because it has a quaternary ammonium group. However, depending on the composition and ratio of a monomer which does not contain a quaternary ammonium group to be copolymerized, water may be used. Some do not dissolve sufficiently. However, even if these polymers can be dissolved in a mixed solvent of a water-miscible organic solvent and water, they can be used in the present invention.
Further, as a cationic polymer, a silane coupling agent having a quaternary ammonium salt structure is hydrolyzed,
Those polycondensed can also be used.

Here, the water-miscible organic solvent includes, for example, alcohols such as methanol, ethanol, isopropanol and n-propanol; glycols such as ethylene glycol, diethylene glycol and glycerin; esters such as ethyl acetate and propyl acetate; A ketone such as acetone and methyl ethyl ketone, and an amide such as N, N-dimethylformamide, etc., are usually organic solvents that can be dissolved in water by 10% or more. The amount of the water-miscible organic solvent used is preferably equal to or less than the amount of water used.

The cationic polymer used in the present invention preferably has a number average molecular weight (Mn) of 100,000 or less.
Here, the number average molecular weight is a value converted into a polyethylene glycol value determined by gel permeation chromatography (GPC).

When the number average molecular weight exceeds 100,000,
When a solution of a cationic polymer is added to a dispersion containing inorganic fine particles having an anionic surface, agglomerates are generated intensely. A large number of particles are present, making it difficult to form a uniform dispersion. A particularly preferred number average molecular weight is 50,000 or less. The number average molecular weight of the cationic polymer is usually preferably 2000 or more from the viewpoint that the dye is adsorbed on the cationic polymer to prevent bleeding and outflow of the dye by water.

In the present invention, the ratio of the colloidal silica to the cationic polymer can vary depending on the type and particle size of the colloidal silica, or the type and number average molecular weight of the cationic polymer. In the present invention, the ratio is preferably 1: 0.01 to 1: 1 since the surface of the colloidal silica needs to be stabilized by replacing it with cationic. In the present invention, it is preferable to gradually replace the anionic portion of the colloidal silica having an anionic surface with the cation portion of the cationic polymer so as to finally make the cation portion excessive, and therefore, a method of adding the colloidal silica and the cationic polymer Care must be taken, and it is preferable to add colloidal silica to the cationic polymer solution.

On the other hand, when the cationic polymer solution is added to the colloidal silica while stirring, the whole solution becomes one huge lump in the middle and stirring becomes almost difficult. The reason for this is that when the cationic polymer is gradually added while the entire liquid is anionic,
It is presumed that the anion is gradually reduced and the liquid as a whole tends to form a huge mass because it passes through the neutral region in the middle of charge. Even in such a case, if a sufficient amount of the cationic polymer is present, a sufficient stirring is carried out over a long period of time to eventually gradually liquefy, but this is not preferable in terms of production efficiency.

By gradually adding colloidal silica to the cationic polymer solution, a dispersion can be obtained because the entire liquid is always kept cationic, which is preferable. On this occasion,
In the process of adding colloidal silica, it is preferable to perform sufficient stirring. In some cases, it is preferable to use a disperser during or after the addition in terms of production efficiency.

In the mixed solution thus obtained, when viewed microscopically, a large number of fine lump-like aggregates are present. This is presumed to be due to the lack of cationic polymer relative to colloidal silica locally at the location where the colloidal silica was added, resulting in the formation of an unstable charge.

Such fine lump-like aggregates are reduced by performing a subsequent dispersion treatment. Examples of the dispersion treatment method include various conventionally known dispersion methods 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. A disperser can be used, but 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.

The ultrasonic disperser normally irradiates an ultrasonic wave of 20 to 25 kHz and disperses energy by concentrating energy on a solid-liquid interface, and is dispersed very efficiently.
It is not very suitable when a large amount of dispersion needs to be prepared. On the other hand, a 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 screws or hydraulic pressure. Then, the flow of the liquid medium sent by the high-pressure pump is restricted by the homogeneous valve and pressure is applied. At the moment when the medium passes through the homogeneous valve, fine lump material is crushed.

This dispersion treatment 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 homogenous valve is usually 50-
The dispersion is 1000 kg / cm ² , and the dispersion can be performed in one pass or can be repeated many times. Two or more of the above dispersion processing methods can be used in combination.

When preparing the above-mentioned dispersion, it can be prepared by adding various additives. For example, various nonionic or cationic surfactants (anionic surfactants are not preferred because they form aggregates),
Antifoaming agent, nonionic hydrophilic polymer (eg, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, polyacrylamide, various sugars, gelatin, pullulan, etc.), nonionic or cationic latex dispersion, water-miscible organic solvent (Ethyl acetate, methanol, ethanol, isopropanol, n-propanol, acetone, etc.), inorganic salts, pH adjusters, etc., can be used as needed.

In particular, a water-miscible organic solvent is preferable because the formation of fine lumps when colloidal silica and a cationic polymer are mixed is suppressed. Such a water-miscible organic solvent is preferably present in the dispersion at 0.1 to 20% by weight,
Particularly preferably, 0.5 to 10% by weight is used. The pH at which the cationic dispersion is prepared can vary widely depending on the type of colloidal silica, the type of cationic polymer, various additives, etc., but generally the pH is 1 to 8,
Particularly, 2 to 7 are preferable.

In the ink jet recording paper of the present invention, it is preferable that boric acid and / or borate is contained in the ink absorbing layer in order to enhance the film forming property by crosslinking the ink absorbing layer. The boric acid or a salt thereof refers to an oxygen acid having a boron atom as a central atom and a salt thereof, and specifically, orthoboric acid, diboric acid, metaboric acid, tetraboric acid, pentaboric acid, and octaboric acid. Includes acids and their salts. These boric acids or salts thereof are used in an amount of 0.05 to ² g, preferably 0.1 to 1 g per 1 m ^{2 of} recording paper.
Used in the range.

The support used for the recording paper of the present invention is preferably a non-water-absorbing support, and may be a transparent support or an opaque support. Examples of the transparent support include, for example, a film made of a material such as a polyester resin, a diacetate resin, a triacetate resin, an acrylic resin, a polycarbonate resin, a polyvinyl chloride resin, a polyimide resin, cellophane, and celluloid. No.

When the recording paper of the present invention is used as an OHP, a support having a property of resisting radiant heat is preferable, and a polyester resin, particularly, polyethylene terephthalate is preferable in terms of cost. The thickness of such a transparent support is preferably about 10 to 200 μm.

Examples of the opaque support include resin-coated paper (so-called RC paper) having a polyolefin resin-coated layer in which a white pigment or the like is added to at least one of base papers; polyethylene terephthalate (PET); So-called white PET obtained by adding a white pigment such as titanium is preferable. When a colorant image-receiving layer is provided on a support, a corona discharge treatment or a subbing treatment is performed on the support prior to the application of the colorant-receiving layer, for the purpose of increasing the adhesive strength between the support and the colorant image-receiving layer. It is preferable to perform the above. Furthermore,
The ink jet recording paper of the present invention does not necessarily need to be colorless, and may be colored.

In the ink jet recording paper of the present invention, when a paper support in which both sides of the base paper are laminated with polyethylene is used as the support, the recorded image is close to photographic quality, and a high quality image can be obtained at low cost. Especially preferred for.

Hereinafter, the paper support laminated with the above polyethylene will be described. The base paper used for the paper support can be obtained by making wood pulp as a main raw material and adding synthetic pulp such as polypropylene or synthetic fiber such as nylon or polyester as necessary. For wood pulp, LBKP, LBSP, NB
KP, NBSP, LDP, NDP, LUKP, NUKP
Can be used, but LBK having a large amount of short fibers
It is preferable to use more P, NBSP, LBSP, NDP, and LDP. However, LBSP and / or L
The ratio of DP is preferably from 10 to 70% by weight. As the pulp, a chemical pulp (sulfate pulp or sulfite pulp) having a small amount of impurities is preferably used, and pulp having improved whiteness by 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 pulp used for papermaking is determined by CSF
The fiber length after beating is 30 to 70% when represented by the sum of 24 mesh residual weight% and 42 mesh residual weight% specified in JIS P 8207. It is preferred that In addition,
The weight percentage of the remaining 24 mesh is preferably not more than 20 weight%. The basis weight of the base paper is preferably 30 to 250 g,
Particularly, 50 to 200 g is preferable. Base paper thickness is 40-2
50 μm is preferred.

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 agents as those which can be added to the base paper can be used. The pH of the base paper is preferably 5 to 9 when measured by a hot water extraction method specified in JIS P 8113.

The polyethylene covering the front and / or back side of the base paper is mainly low density polyethylene (LDPE)
And / or high-density polyethylene (HDPE), but other LLDPE, polypropylene, etc. may also be used in part. 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 about 3 to 20 with respect to polyethylene.
% By weight, preferably 4 to 13% by weight.

The polyethylene-coated paper can be used as glossy paper, or when polyethylene is melted, extruded and coated on the surface of a base paper, a so-called embossing treatment is performed to obtain a matte sheet which can be obtained with ordinary photographic printing paper. It can be used even if a surface or a silk surface is formed. The amount of polyethylene used on the front and back of the base paper is selected so as to optimize the curl in low and high humidity after providing the ink receiving layer and the back layer, but the polyethylene layer on the ink receiving layer side is generally used. The thickness is 20 to 40 μm, and the thickness of the back layer is 10 to 30 μm.

Further, the polyethylene-coated paper support preferably has the following characteristics. 1) Tensile strength: strength specified in JIS P 8113, 2-30 kg in the vertical direction, 1-20 kg in the horizontal direction 2) Tear strength: 10-200 g in the vertical direction, horizontal direction in the method specified by JIS P 8116 20) to 200 g 3) Elasticity: Compressive elastic modulus ≧ 103 kgf / cm ² 4) Surface Beck smoothness: 20 seconds or more (gloss surface) under the conditions specified in JIS P 8119, and less than this for molded products 5) Opacity : Under measurement conditions of linear light incidence / diffuse light transmission conditions, the transmittance of light in the visible region is 20% or less (particularly 15%
Less than)

In the ink jet recording paper of the present invention, a water-soluble reducing agent, a sulfur-containing compound or an emulsified dispersion of a hydrophobic antioxidant can be added to the ink absorbing layer as a discoloration preventing agent. The water-soluble reducing agent is described in JP-A-8-3.
No. 00807, 8-150773, 8-
No. 108617, No. 9-267544, and the like. For example, sulfites, nitrites, phosphites, thiosulfates, ascorbic acid or salts thereof, hydroxylamine derivatives (eg, N, N-diethyl Hydroxylamine, N, N-disulfoethylhydroxylamine sodium salt, N-hydroxyphthalimide,
N, N-dicarboxyethylhydroxylamine / sodium salt), glucose and the like.

The above sulfur-containing compounds are described in JP-A-61-177.
Nos. 279, 61-163886 and 64-
No. 36479, JP-A-7-314883, JP-A-7-314882 and 1-1115677, and examples thereof include thiocyanate, thiourea, 2-mercaptobenzimidazole, and 2-mercapto. Benzthiazole, 2-mercaptobenzoxazole, 5-mercapto-1-methyltetrazole, 2,5
-Dimercapto-1,3,4-triazole, 2,4,
6-trimercaptocyanuric acid, thiosalicylic acid, thiouracil, 1,2-bis (2-hydroxyethylthio)
Ethane and the like. Examples of the hydrophobic antioxidant include JP-A-57-74192 and JP-A-57-879.
No. 89, JP-A-1-115667 and 3-1
Known antioxidants, such as those described in JP-A-3376, can be used. Particularly preferred antioxidants are so-called hindered phenolic antioxidants in which at least one of the ortho positions of the hydroxyl group is substituted by a tertiary alkyl group, and two carbon atoms linked to a nitrogen atom are both substituted by an alkyl group. Piperidine-based antioxidants (so-called hindered amines), phenols or polyhydroxybenzenes in which at least one hydroxyl group is etherified with an alkyl group.

The hydrophobic antioxidant is preferably used together with a hydrophobic high-boiling organic solvent (eg, di-2-ethylhexyl phthalate, di-i-decyl phthalate, tricresyl phosphate, tri-2-ethylhexyl phosphate) to form a hydrophilic antioxidant. It is added in a state of being emulsified and dispersed in a binder. When the hydrophobic antioxidant is dissolved in an organic solvent such as acetone or methanol and added, or added by a wet pulverization method, the effect of preventing fading is small.

The ratio between the hydrophobic antioxidant and the high-boiling organic solvent is approximately 1: 5 to 10: 1 by weight. Further, it may contain a water-soluble polyvalent metal ion for the purpose of preventing bleeding after printing.

Examples of the water-soluble polyvalent metal ion that can be used include divalent to tetravalent polyvalent metal ions. Specifically, Ca ²⁺ , Mg ²⁺ , Zn ²⁺ , Cu ²⁺ , Fe ³⁺ , N
i ²⁺ , Co ²⁺ , Al ^{3+ and the} like.
a ²⁺ , Mg ²⁺ , Zn ²⁺ , and Al ³⁺ are preferable. The addition amount of the polyvalent metal ion, generally per recording sheet 1 m ² 0.1 to 1
0 mmol. When the amount is less than 0.1 mmol, the effect is small, and when it exceeds 10 mmol, aggregation of the dye is promoted, and the bronzing phenomenon on the surface is easily caused.
Particularly preferred is 0.2 to 2 mmol. Various additives other than those described above can be added to the ink absorbing layer provided on the ink jet recording paper of the invention and other layers provided as needed.

Examples of these additives include polystyrene, polyacrylates, polymethacrylates, polyacrylamides, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, and copolymers thereof, and urea resins. Or latex fine particles of melamine resin or the like; various cationic or nonionic surfactants; JP-A-57-74193;
UV absorbers described in JP-A-7-87988 and JP-A-62-261476; JP-A-57-74192, JP-A-57-87989, JP-A-60-72785, JP-A-61-146591, 1-950 Kaihei
No. 91 and No. 3-13376; anti-fading agents described in JP-A-59-42993;
Nos. 9-52689 and 62-280069,
JP 61-242871 and JP-A-4-21926
No. 6, etc .; fluorescent brighteners; sulfuric acid, phosphoric acid,
PH adjusting agents such as citric acid, sodium hydroxide, potassium hydroxide and potassium carbonate; and various known additives such as antifoaming agents, preservatives, thickeners, antistatic agents and matting agents. The porous colorant receiving layer may be composed of two or more layers. In this case, the constitution of these two or more layers may be the same or different.

For coating the colorant receiving layer and the undercoat layer of the ink jet recording paper of the present invention, and other various hydrophilic layers appropriately provided as necessary, on a support, a known coating method is appropriately selected. Can be used. A preferred method is to coat and dry a coating solution constituting each layer on a support. In this case, two or more layers can be applied simultaneously, and in particular, simultaneous application in which all the hydrophilic binder layers need only be applied once is preferable.

Examples of the coating method include a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a curtain coating method, and an extrusion method using a hopper described in US Pat. No. 2,681,294. The coating method is preferably used. When performing image recording using the inkjet 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 a colorant, a 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. Among them, those having a particularly large effect are those containing a phthalocyanine dye as a cyan dye. Phthalocyanine dyes are particularly widely known and used among cyan dyes.

Examples of the solvent for the aqueous ink include water and various water-soluble organic solvents, for example, alcohols such as methyl alcohol, i-propyl alcohol, butyl alcohol, t-butyl alcohol, and i-butyl alcohol; dimethylformamide, dimethyl alcohol Amides such as acetamide;
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, 1,2,2 6-hexanetriol, thiodiglycol, hexylene glycol,
Polyhydric alcohols such as diethylene glycol, glycerin and triethanolamine; and lower alkyl ethers of polyhydric alcohols such as ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether and triethylene glycol monobutyl ether.

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

Other additives for the aqueous ink include, for example, a pH adjuster, a metal sequestering agent, a fungicide, a viscosity adjuster,
Examples include surface tension modifiers, wetting agents, surfactants, and rust inhibitors. The aqueous ink liquid is 25 to 60 dyn / 20 ° C. in order to improve the wettability on the recording paper.
cm, preferably in the range of 30 to 50 dyn / cm.

[0068]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Below, the silica mixed aqueous dispersion used in the examples (a)
To (f).

-Silica mixed aqueous dispersion (a)-While stirring 69.4 L of the following silica mixed aqueous dispersion (A), 7.0 L of an aqueous solution containing 270 g of boric acid and 230 g of borax was added, and 1 g of a foaming agent (SN381: manufactured by San Nopco) was added. This mixed solution was subjected to a pressure of 250 kg / cm ^{2 with} a high pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd.
The mixture was dispersed once and the whole amount was adjusted to 79 L with pure water to prepare a substantially clear silica dispersion liquid (a).

-Silica mixed water dispersion (b)-While stirring the following silica mixed water dispersion (B) (69.4 L), 7.0 L of an aqueous solution containing 270 g of boric acid and 230 g of borax was added, and 1 g of a foaming agent (SN381: manufactured by San Nopco) was added. This mixed solution was subjected to a pressure of 250 kg / cm ^{2 with} a high pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd.
The mixture was dispersed once and the whole amount was adjusted to 79 L with pure water to prepare a substantially clear silica dispersion liquid (b).

-Silica mixed water dispersion (c)-18 L of a water mixed solution (pH = 2.5) containing 1.29 kg of cationic polymer (P-10), 4.2 L of ethanol and 1.5 L of n-propanol 69.4 L of the following silica mixed aqueous dispersion (A) was added to the mixture while stirring, and then 7.0 L of an aqueous solution containing 270 g of boric acid and 230 g of borax was added, and an antifoaming agent (SN381: Sannopco Co., Ltd.) was added. 1 g) was added. This mixed solution was dispersed twice with a high-pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd. at a pressure of 250 kg / cm ² , and the whole amount was made up to 97 L with pure water to prepare a substantially clear silica dispersion (C).

-Silica mixed water dispersion (d)-18 L of a water mixed solution (pH = 2.5) containing 1.29 kg of the cationic polymer (P-10), 4.2 L of ethanol and 1.5 L of n-propanol Was added while stirring with 69.4 L of the following silica-mixed aqueous dispersion (B), and then 7.0 L of an aqueous solution containing 270 g of boric acid and 230 g of borax was added, and an antifoaming agent (SN381: Sannopco) was added. 1 g). This mixed solution was subjected to a pressure of 250 kg / cm ^{2 with} a high pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd.
The mixture was dispersed once and the total amount was made up to 97 L with pure water to prepare a substantially clear silica dispersion (C).

-Silica mixed aqueous dispersion (e)-Snowtex-O (primary particle diameter 10-20 nm, 20
% Aqueous dispersion) (Nissan Chemical Industries) (Colloidal silica)
While stirring 62.5 L, 270 g of boric acid and borax 2
7.0 L of an aqueous solution containing 30 g was added, and an antifoaming agent (S
N381: San Nopco). This mixed solution is subjected to 250k with a high pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd.
The mixture was dispersed twice at a pressure of g / cm ² , and the total amount was adjusted to 97 L with pure water to prepare an almost clear silica dispersion liquid (e).

-Silica mixed water dispersion (f)-18 L of a water mixed solution (pH = 2.5) containing 1.29 kg of the cationic polymer (P-10), 4.2 L of ethanol and 1.5 L of n-propanol , Snowtex-
62.5 L of O (primary particle diameter 10 to 20 nm, 20% aqueous dispersion) (manufactured by Nissan Chemical Industries, Ltd.) (colloidal silica) is added with stirring, and then 270 g of boric acid and borax 23 are added.
7.0 L of an aqueous solution containing 0 g was added, and an antifoaming agent (SN
381: San Nopco). 250 kg of this mixed solution using a high pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd.
/ Cm ² twice, and the whole amount was made up to 79 L with pure water to prepare an almost clear silica dispersion liquid (f).

<< Silica mixed aqueous dispersion (A) >> Snowtex-O (20% aqueous dispersion having a primary particle diameter of 10 to 20 nm) (Nissan Chemical Industries, Ltd.) (colloidal silica)
AEROSIL300 (primary particle size 7n) in 5kg
m) (manufactured by Nippon Aerosil Co., Ltd.) (fumed silica) 62.5
The kg was suction-dispersed at room temperature using a jet stream inductor mixer TDS manufactured by Mitamura Riken Kogyo Co., Ltd., and the whole amount was made up to 694 L with pure water.

<< Silica Mixed Water Dispersion (B) >> 521 kg of Snowtex-PS-SO (12% aqueous dispersion) (manufactured by Nissan Chemical Industries, Ltd.) (beaded colloidal silica)
62.5 kg of ROSIL300 (primary particle diameter 7 nm) (manufactured by Nippon Aerosil Co., Ltd.) (vapor-phase silica) was suction-dispersed at room temperature using a jet stream inductor mixer TDS manufactured by Mitamura Riken Kogyo Co., Ltd. 6
Finished with pure water to 94L.

Example 1 While stirring at 40 ° C., a silica mixed aqueous dispersion (a) 53
The following additives were sequentially mixed with 0 ml to prepare a coating liquid (1). (1) 10% aqueous solution of polyvinyl alcohol (Kuraray Industries: Kuraray Poval PVA203): 0.6 ml (2) 5% aqueous solution of polyvinyl alcohol (Kuraray Industries: Kuraray Poval PVA235): 442.8 ml (3) Pure Make up to 1000 ml with water.

The above coating solution was applied to a paper support (thickness: 220 μm: 13% by weight of anatase type titanium oxide based on polyethylene in the polyethylene on the colorant absorbing layer side) coated on both sides with polyethylene. 180 μm
To obtain an ink jet recording paper.
Coating is performed by heating the coating solution to 40 ° C., coating with a slide hopper, and immediately after coating in a cooling zone maintained at 0 ° C.
After cooling for 2 seconds, 45 ° C. for 60 seconds with a wind of 20-30 ° C.
For 60 seconds and then at 50 ° C. for 60 seconds.

With respect to the obtained ink jet recording paper, the water absorption and the ink absorbency were evaluated as follows. Table 1 shows the obtained results. (1) Water absorption The water absorption of the ink absorbing layer was measured by the following method, and the absorbability was evaluated. The recording paper is cut into a size of 10 cm × 10 cm, and the dry weight (this is referred to as (a)) is measured. Thereafter, the substrate is immersed in pure water for 30 seconds, the water on the surface is wiped off, and the weight after the immersion (this is referred to as (b)) is measured. In addition, the weight of only the paper support having both sides coated with polyethylene without the ink absorbing layer (this is referred to as (c)) is measured. From the obtained values (a), (b) and (c), the water absorption is calculated as follows. It is assumed that the water absorption of the paper support coated on both sides with polyethylene was zero. Water absorption = ((b)-(a)) / ((a)-(c))

(2) Ink Absorbability Overprinting was performed with an ink jet printer DesignJet 2000CP manufactured by Hewlett-Packard Company at 100% output for each of three colors of YMC ink and a total of 300%. The state of the printing surface immediately after printing was visually observed and evaluated as follows. ：: The ink is uniformly absorbed. Δ: Ink was not partially absorbed and unevenness occurred. X: The ink is overflowing over the entire surface.

Example 2 A silica-mixed aqueous dispersion (b) 53 was stirred at 40 ° C.
The following additives were sequentially mixed with 0 ml to prepare a coating liquid (2). (1) 10% aqueous solution of polyvinyl alcohol (Kuraray Industries: Kuraray Poval PVA203): 0.6 ml (2) 5% aqueous solution of polyvinyl alcohol (Kuraray Industries: Kuraray Poval PVA235): 442.8 ml (3) Pure Make up to 1000 ml with water.

Using the above coating liquid (2) instead of coating liquid (1), coating and drying were carried out in the same manner as in Example 1 to obtain an ink jet recording paper. The obtained ink jet recording paper was evaluated for water absorption and ink absorbability in the same manner as in Example 1. Table 1 shows the obtained results.

Example 3 While stirring at 40 ° C., a silica mixed water dispersion (C) 65
The following additives were sequentially mixed with 0 ml to prepare a coating liquid (3). (1) 10% aqueous solution of polyvinyl alcohol (Kuraray Industries: Kuraray Poval PVA203): 0.6 ml (2) 5% aqueous solution of polyvinyl alcohol (Kuraray Industries: Kuraray Poval PVA235): 270 ml (3) Pure water Make up the total volume to 1000 ml.

Instead of the coating liquid (1), the coating liquid (3) was applied and dried in the same manner as in Example 1 to obtain an ink jet recording paper. The obtained ink jet recording paper was evaluated for water absorption and ink absorbability in the same manner as in Example 1. Table 1 shows the obtained results.

Example 4 While stirring at 40 ° C., a silica mixed water dispersion (d) 65
The following additives were sequentially mixed with 0 ml to prepare a coating liquid (4). (1) 10% aqueous solution of polyvinyl alcohol (Kuraray Industries: Kuraray Poval PVA203): 0.6 ml (2) 5% aqueous solution of polyvinyl alcohol (Kuraray Industries: Kuraray Poval PVA235): 270 ml (3) Pure water Make up the total volume to 1000 ml.

Instead of the coating liquid (1), the coating liquid (4) was applied and dried in the same manner as in Example 1 to obtain an ink jet recording paper. The obtained ink jet recording paper was evaluated for water absorption and ink absorbability in the same manner as in Example 1. Table 1 shows the obtained results.

Comparative Example 1 A silica-mixed aqueous dispersion (e) 53 was stirred at 40 ° C.
The following additives were sequentially mixed with 0 ml to prepare a coating liquid (5). (1) 10% aqueous solution of polyvinyl alcohol (Kuraray Industries: Kuraray Povar PVA203): 0.6 ml (2) 5% aqueous solution of polyvinyl alcohol (Kuraray Industries: Kuraray Poval PVA235): 442.8 ml (3) Pure Make up to 1000 ml with water.

Instead of the coating liquid (1), the coating liquid (5) was applied and dried in the same manner as in Example 1 to obtain an ink jet recording paper. The obtained ink jet recording paper was evaluated for water absorption and ink absorbability in the same manner as in Example 1. Table 1 shows the obtained results.

Comparative Example 2 While stirring at 40 ° C., a silica mixed water dispersion (f) 65
The following additives were sequentially mixed with 0 ml to prepare a coating liquid (6). (1) 10% aqueous solution of polyvinyl alcohol (Kuraray Industries: Kuraray Poval PVA203): 0.6 ml (2) 5% aqueous solution of polyvinyl alcohol (Kuraray Industries: Kuraray Poval PVA235): 270 ml (3) Pure water Make up the total volume to 1000 ml.

Instead of the coating liquid (1), the coating liquid (6) was applied and dried in the same manner as in Example 1 to obtain an ink jet recording paper. The obtained ink jet recording paper was evaluated for water absorption and ink absorbability in the same manner as in Example 1. Table 1 shows the obtained results.

[0091]

[Table 1]

From the results shown in Table 1, it can be seen that the ink jet recording paper of the present invention has excellent ink absorbency.

[0093]

The ink jet recording paper of the present invention has excellent ink absorbency.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H086 BA15 BA21 BA33 BA35 4L055 AG18 AG23 AG64 AG71 AH02 AH37 AH50 AJ01 BE09 FA30 GA09

Claims (7)

[Claims] 1. An ink jet recording sheet comprising a support provided with a colorant receiving layer, wherein the colorant receiving layer is formed from fumed silica, colloidal silica, and a water-soluble polymer. Ink jet recording paper. 2. The ink jet recording paper according to claim 1, wherein the colloidal silica is a bead-shaped colloidal silica. 3. The ink jet recording paper according to claim 1, wherein the weight ratio of fumed silica to colloidal silica is 1:20 to 20: 1. 4. The ink-jet recording paper according to claim 1, wherein the water-soluble polymer is polyvinyl alcohol. 5. The ink jet recording paper according to claim 1, wherein the color material receiving layer contains boric acid and / or borate. 6. The ink jet recording paper according to claim 1, wherein the color material receiving layer contains a cationic polymer. 7. The paper according to claim 1, wherein the support is a paper in which the surface of a base paper is coated with a polyolefin resin.
The inkjet recording paper according to any one of the above.