JPH11321080A - Ink jet recording paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the slip properties of a surface without deteriorating the degree of luster so much by a method wherein a plurality of porous layers are formed on a substrate and monodisperse matting agent, provided with the degree of dispersion of a specified value or less, is contained in the uppermost layer positioned at the most distant side among the porous layers from the substrate. SOLUTION: A plurality of porous layers, containing inorganic fine particles, employing white inorganic pigment such as light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate or the like, and a hydrophilic binder such as gelatin, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid or the like, are formed on a substrate. Monodisperse matting agent, having the degree of dispersion of 2 or less, is contained in the uppermost layer positioned at the most distant side among the porous layers from the substrate. According to this method, the slip properties of a surface can be improved without deteriorating the degree of luster of the surface so much.

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 a high gloss ink jet recording sheet having improved transportability and paper feedability.

[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 from both the ink and device aspects.
It is rapidly spreading in various fields such as facsimile 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.

[0006] For example, a recording paper described in JP-A-52-53012 in which a paint for surface processing is wetted on a low-size base paper, and a support surface described in JP-A-55-5830 is disclosed. Recording paper having an ink-absorbing coating layer thereon, recording paper containing a non-colloidal silica powder as a pigment in a wearable layer described in JP-A-56-157, JP-A-57-107878. Japanese Patent Application Laid-Open No.
JP-A-110287 discloses a recording sheet having two pore distribution peaks, JP-A-62-111782 discloses a recording sheet comprising two upper and lower porous layers, and JP-A-59-68292. No. 59-123696
Recording paper having irregular cracks described in JP-A-61-13578 and JP-A-60-18383.
No. 6, No. 61-148092 and No. 62-14947
JP-A-63-252779, JP-A-1-1080
No. 83, No. 2-136279, No. 3-65376 and No. 3-27976, etc., recording paper containing pigments having specific physical properties and fine-particle silica,
JP-A-57-14091, JP-A-60-219083,
Nos. 60-210984, 61-20797, 6
1-1188183, JP-A-5-278324, 6
No. 92011, No. 6-183134, No. 7-137
No. 431, No. 7-276789, and the like, and recording paper containing fine particle silica such as colloidal silica, and JP-A-2-276671, JP-A-3-67684.
Nos. 3-215082, 3-251488, 4-67986, 4-263983, and 5-1
There are many known recording papers containing alumina hydrate fine particles described in, for example, Japanese Patent No. 6517.

Among the above, the 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 a relatively high gloss can be obtained. It is.

However, since the surface of the high gloss ink jet recording paper has a relatively high smoothness, there is a problem in the paper feeding when a plurality of papers are fed one upon another and in the transportability inside the recording apparatus. Often easy.

This problem is ameliorated by adding relatively coarse particles, so-called matting agents, to the surface.

However, when the ink receiving layer is a void type, the ink receiving layer itself contains fine particles, so that the surface thereof has a lower gloss than an ink jet recording paper made of a hydrophilic binder alone, and usually has a lower gloss. It has been found that the use of a matting agent as used has a disadvantage that the glossiness tends to be extremely reduced.

JP-B-63-65036 and JP-B-63-6
No. 5038 describes a recording material containing filler particles that are exposed on the surface of the ink receiving layer at 10,000 to 100,000 particles per mm ^{2 of} 3 to 25 μm in size.

However, it has been found that such a recording material cannot obtain a sufficient glossiness because of too many filler particles.

[0013]

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 paper having a void layer composed of inorganic fine particles and a hydrophilic binder, which has a high glossiness. An object of the present invention is to provide an ink jet recording sheet which has improved paper feeding properties and transportability inside a recording apparatus by improving the surface slipperiness without significantly lowering the degree.

[0014]

The above object of the present invention is achieved by the following constitution.

1. A monodisperse matting agent having a plurality of void layers containing inorganic fine particles and a hydrophilic binder on a support, and having a dispersity of 2 or less in an uppermost layer of the void layers located farthest from the support. An inkjet recording paper comprising:

Hereinafter, the present invention will be described in detail.

The void layer of the ink jet recording paper of the present invention contains inorganic fine particles. Examples of such inorganic fine particles 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, White inorganic pigments such as hydrotalcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone, zeolite, magnesium hydroxide, etc. Can be mentioned.

Such inorganic fine particles can be used either as primary particles or in a state where secondary aggregated particles are formed.

In the present invention, silica or pseudo-boehmite is preferred from the viewpoint that particularly fine voids can be formed,
In particular, silica, colloidal silica, and pseudoboehmite synthesized by a gas phase method having an average particle diameter of 100 nm or less are preferable.

The average particle size of the inorganic fine particles can be determined by observing the cross section or surface of the particles or the void layer with an electron microscope.
The particle size of any number of particles is determined, and the value is determined as a simple average value (number average). Here, each particle size is represented by a diameter assuming a circle equal to the projected area.

As the hydrophilic binder used for the void layer, any conventionally known hydrophilic binder can be appropriately selected and used, for example, gelatin, polyvinyl alcohol,
Examples include polyvinylpyrrolidone, polyethylene oxide, polyacrylic acid, polyacrylamide, agar, carrageenan, dextran, dextrin, pullulan, hydroxyethyl cellulose, and carboxymethyl cellulose.

Two or more of these hydrophilic binders can be used in combination.

A particularly preferred hydrophilic binder is polyvinyl alcohol.

The polyvinyl alcohol used in the present invention includes, in addition to ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, polyvinyl alcohol having a cation-modified terminal or anion-modified polyvinyl alcohol having an anionic group. Of modified polyvinyl alcohol.

The polyvinyl alcohol obtained by hydrolyzing vinyl acetate preferably has an average degree of polymerization of 300 or more, and particularly preferably has an average degree of polymerization of 1,000 to 4,000.

The degree of saponification 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 used in the main chain or side chain of the polyvinyl alcohol. Which is 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-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,
Hydroxyethyltrimethylammonium chloride,
Trimethyl- (methacrylamidopropyl) ammonium chloride, N- (1,1-dimethyl-3-dimethylaminopropyl) acrylamide and the like.

The ratio of the cation-modified group-containing monomer of the cation-modified polyvinyl alcohol is 0.1 to 10 mol%, preferably 0.2 to 5 mol%, based on vinyl acetate.

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 disclosed in
Modified polyvinyl alcohol having a water-soluble group as described in -285265.

Examples of the nonion-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. And a block copolymer of a vinyl compound having a hydrophobic group and vinyl alcohol described in Japanese Patent Application Laid-Open Publication No. H11-157,086.

Two or more kinds of polyvinyl alcohols such as different degrees of polymerization and different types of modification can be used in combination.

The amount of the inorganic fine particles used is 1 m of recording paper.
^{It is 3 to} 50 g per ² and particularly preferably 5 to 30 g. The amount of the hydrophilic binder used is 1 m ² of recording paper.
0.5 to 10 g, especially 1 to 5 g per unit. The ratio of the inorganic fine particles to the hydrophilic binder is approximately 3 to 10 in weight ratio.

The void layer contains boric acid or a salt thereof in order to improve the film forming property of the film and increase the strength of the film. The boric acid or a salt thereof refers to an oxyacid having a boron atom as a central atom and a salt thereof, and specifically includes orthoboric acid, metaboric acid, hypoboric acid, tetraboric acid, pentaboric acid and salts thereof.

The amount of boric acid or a salt thereof can vary widely depending on the amount of the inorganic fine particles and the hydrophilic binder in the coating solution.
Preferably it is 5 to 40% by weight.

The ink jet recording paper of the present invention has at least two layers of the above-mentioned void layer on a support, and contains a monodisperse matting agent having a degree of dispersion of 2 or less in the uppermost layer farthest from the support. Things.

The matting agent used in the present invention is water-insoluble organic or inorganic particles such as titanium oxide, silica particles, glass powder, barium sulfate, polystyrene, polymethyl methacrylate, polycarbonate and polyacrylate copolymer. Any particles can be used in the present invention as long as they are particles and have a degree of dispersion of 2 or less. The matting agent preferably used in the present invention is represented by the following general formula (1).

[0038]

Embedded image

In the formula, R ₁ , R ₂ and R ₃ each represent a hydrogen atom, an alkyl group or an aryl group, and R ₄ and R ₅ each represent an alkyl group, an aryl group or a heterocyclic group. M
Represents a hydrogen atom or a cationic group. x, y and z each represent a molar ratio of the ethylenically unsaturated compound, and z / (x
+ Y) <0.3.

Specific examples of the composition of the matting agent particles particularly preferably used in the present invention are shown below.

[0041]

Embedded image

The degree of dispersion referred to in the present invention is defined as (、 NV ² / ΣNV) (where V represents the diameter of each particle) from the equivalent particle diameter of a sphere obtained by measuring the particle size distribution of a matting agent using a Coulter counter. , N represents the number of particles having a particle diameter of V), and shows a value represented by a ratio of standard deviation / average particle diameter from the standard deviation and the average particle diameter calculated based on the standard.

In the present invention, the degree of dispersion of the matting agent is 2
Or less, preferably 1.0 or less, particularly 0.8
The following is preferred.

The average particle size of the matting agent used in the present invention is preferably at least 2 μm, more preferably at least 5 μm, larger than the dry film thickness of the uppermost layer to which the matting agent is added. The dry film thickness of the uppermost layer is generally 1 to 20 μm, and the matting agent preferably has an average particle diameter larger than the dry film thickness by 2 μm or more, preferably 5 μm or more.

The upper limit of the average particle size of the matting agent is determined by the tactile sensation of the surface and the likelihood of occurrence of abrasion, etc., but is generally not more than 30 μm larger than the dried film thickness of the uppermost layer.
In particular, a size not larger than 20 μm is preferable.

The amount of the matting agent to be used is 10 to 300 per 1 mm ^{2 of} the ink jet recording paper, and the surface smoothness can be improved without significantly lowering the gloss.

The dry thickness of the uppermost layer to which the above-mentioned matting agent is added is in the range of 1 to 20 μm, preferably 3 to 15 μm.

The ink jet recording paper of the present invention has at least two or more void layers, and a matting agent is added to the uppermost layer.

When the matting agent is added to this layer with only one void layer, it is necessary to use a larger matting agent in order to obtain a sufficient effect of improving the slipperiness of the surface. Cracks are liable to occur in the void layer formed of a hard film, or the height of the particles protruding from the surface is too large, so that the tactile sensation of the surface is significantly impaired or easily damaged.

From this viewpoint, the dried film thickness of the uppermost layer is preferably about 1/2 or less of the entire void layer, and most preferably 1/3 or less.

The total dry thickness of the void layer is generally 10 to 60 μm.
m, preferably 15 to 50 μm.

The ink jet recording paper of the present invention is a recording paper which obtains a high gloss by minimizing a reduction in gloss due to a matting agent, and has a surface gloss (75 ° mirror gloss specified in JIS Z8741) of 40% or more. The glossiness is preferably 50% or more.

The glossiness of the surface of the recording paper depends on the matting agent in the uppermost layer as described above. In addition, the glossiness of the support and the inorganic fine particles constituting the uppermost layer and the void layer thereunder are also provided. It is also affected.

The support preferably has a gloss of about 20% or more. The inorganic fine particles preferably have a gloss of 1% or more.
Those having an average particle size of 00 nm or less are preferable from the viewpoint of obtaining high glossiness.

It is also preferable to add oil droplets having an average particle diameter of 0.2 μm or less to the uppermost layer in order to improve gloss. As such oil droplets, a dispersion of silicone oil is particularly preferred.

Various additives other than those described above can be added to the void layer of the ink jet recording paper of the present invention.

Of these, cationic mordants are preferred for improving water resistance and moisture resistance after printing.

As the cationic mordant, a polymer mordant having a primary to tertiary amino group and a quaternary ammonium group is used, but the discoloration and deterioration of light resistance with time are small, and the mordant ability of the dye is sufficient. Due to its high cost,
Polymer mordants having a quaternary ammonium base are preferred.

Preferred polymer mordants are obtained as a homopolymer of the above-mentioned monomer having a quaternary ammonium salt group, as a copolymer with other monomers or as a condensation polymer.

In addition to the above, see, for example, JP-A-57-741.
Nos. 93, 57-87988 and 62-2
UV absorber described in JP-A-61476;
Nos. 74192, 57-87989, 60-7
Nos. 2785, 61-146591, JP-A-1-95091, and JP-A-3-13376, etc .; anti-fading agents; various anionic, cationic or nonionic surfactants; JP-A-59-42993, JP-A-59-52689, and JP-A-62-280069
JP-A-61-242871 and JP-A-4-24-2
Known additives such as a fluorescent whitening agent, an antifoaming agent, a lubricant such as diethylene glycol, a preservative, a thickener, an antistatic agent, a matting agent and the like described in 19266 and the like can also be contained. .

As the support used for the ink jet recording paper of the present invention, any known support can be used, but a preferred support is a non-water-absorbing support.

Examples of such non-water-absorbing supports include polyester films, diacetate films, triacetate films, acrylic films,
A transparent film made of a material such as a polycarbonate film, a polyvinyl chloride film, a polyimide film, cellophane, or celluloid, or a resin-coated paper having a polyolefin resin coating layer in which a white pigment or the like is added to at least one of base papers (so-called RC) Paper) and a translucent or opaque support such as a so-called white pet obtained by adding a white pigment such as titanium oxide or barium sulfate to polyethylene terephthalate.

In applying the coating composition of the present invention to the support, the support is subjected to a corona discharge treatment, an undercoating treatment or the like for the purpose of increasing the adhesive strength between the surface and the coating layer. Is preferred. Further, the recording paper of the present invention is not necessarily colorless, and may be a colored support.

The support particularly preferably used in the present invention is a transparent polyester film, an opaque polyester film, an opaque polyolefin resin film, and a paper support in which both sides of a base paper support are laminated with polyethylene.

Particularly preferred is a paper support laminated with polyethylene, as described below.

The base paper used for the paper support is made of wood pulp as a main raw material, and if necessary, in addition to wood pulp, is made of synthetic pulp such as polypropylene or synthetic fiber such as nylon or polyester. As wood pulp, LBKP, LBSP, NBKP, NBSP, LDP,
Any of NDP, LUKP and NUKP can be used, but LBKP, NBSP, LBSP, N
It is preferable to use more DP and LDP. However,
The ratio of LBSP and / or LDP is 10% by weight or more,
% By weight or less is preferred.

As the pulp, a chemical pulp containing a small amount of impurities (sulfate pulp or sulfite pulp) 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 the pulp used for papermaking is preferably 200 to 500 cc according to the specification of CSF, and the fiber length after beating is calculated based on 24 mesh residual weight% specified in JIS-P-8207 and 42 mesh. 30% by weight
To 70% is preferable. The weight percentage of the remaining 4 mesh
Is preferably 20% by weight or less.

The basis weight of the base paper is preferably 30 to 250 g, particularly preferably 50 to 200 g. Base paper thickness is 4
It is preferably from 0 to 250 μm.

The base paper can be calendered at the papermaking stage or after the papermaking to give high smoothness. The base paper density is 0.
7 to 1.2 g / m ² (JIS-P-8118) is common. 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.

The pH of the base paper is preferably 5 to 9 as measured by the hot water extraction method specified in JIS-P-8113. The polyethylene covering the front and back surfaces of the base paper is mainly low-density polyethylene ( LDPE) and / or high-density polyethylene (HDPE), but other LLDPE, polypropylene, etc. can also be used partially.

In particular, the polyethylene layer on the coating 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, preferably 4 to 13% by weight, based on polyethylene.

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 perform a coating process. 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 film thickness of the aqueous coating composition and the curl at low and high humidity after the back layer is provided. The polyethylene layer on the side to which the coating composition is applied is 20
４０40 μm, and the thickness of the back layer is 10-30 μm.

Further, the polyethylene-coated paper support preferably has the following characteristics.

Tensile strength: 2 to 30 kg in the vertical direction and 1 in the horizontal direction at a strength specified by JIS-P-8113.
The tear strength is 10 to 200 g in the vertical direction and 20 to 200 in the horizontal direction according to the method defined by JIS-P-8116.
g is preferable. Compression elastic modulus ≧ 10 ³ 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 even if it is less than this in so-called molded products. Good opacity: The transmittance for visible light rays is preferably 20% or less, particularly preferably 15% or less under the measurement conditions of linear light incidence / diffuse light transmission conditions.

In the recording paper of the present invention, the application of a plurality of void layers on a support can be appropriately selected from known methods, but it is preferable to apply all void layers simultaneously.

The coating method includes 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 coating method using a hopper described in US Pat. No. 2,681,294. It is preferably used.

On the side opposite to the side having the void layer of the ink jet recording paper of the present invention, various types of back layers are provided in order to prevent curling, to further improve sticking when superimposed immediately after printing, and to further improve ink transfer. Is preferred.

Although the structure of the back layer varies depending on the type and thickness of the support and the structure and thickness on the front side, generally a hydrophilic binder or a hydrophobic binder is used. The thickness of the back layer is usually in the range of 0.1 to 10 μm.

The surface of the back layer can be roughened in order to prevent sticking to other recording papers, to improve writing properties, and to improve transportability in an ink jet recording apparatus. Organic or inorganic fine particles having a particle size of 2 to 20 μm are preferably used for this purpose.

These back layers may be provided in advance, or may be provided after applying the coating composition of the present invention.

[0085]

EXAMPLES The present invention will be described below in detail with reference to examples, but embodiments of the present invention are not limited thereto. In the examples, “%” indicates absolute dry weight% unless otherwise specified.

Example 1 Preparation of Silica Dispersion B1 The primary particles which have been dispersed uniformly in advance have an average particle size of about 0.1 μm.
450 l of an aqueous solution A1 (pH = 2.6, containing 1% by weight of ethanol) of an 18% aqueous solution A1 of 007 μm fumed silica (A300 manufactured by Nippon Aerosil Co., Ltd.), 16% by weight of a cationic polymer P-1, and n-propanol An aqueous solution C1 containing 5% by weight and 2% by weight of ethanol (pH =
2.7, 2 g of defoamer SN381 manufactured by Sannobuco
(Containing) with stirring at room temperature.

Then, 42 l of a mixed aqueous solution D of boric acid and borax at a 1: 1 weight ratio (each having a concentration of 3% by weight) were gradually added with stirring.

Then, the mixture was dispersed at a pressure of 500 kg / cm ² with a high-pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd., and the total amount was adjusted to 630 liters with pure water to obtain a substantially transparent dispersion.

This dispersion has a filtration accuracy of 30 μm.
Filtration was performed using a TCP-30 type filter manufactured by Advantech Toyo Corporation. Thus, a silica dispersion liquid B1 was prepared.

[0090]

Embedded image

Using the above silica dispersion B1, the following four types of coating liquids were prepared for coating an ink jet recording paper having a four-layer structure. (All values are for coating liquid 1
The amount was shown per 1 and the order of addition was mixed in the order described. 1) Coating solution for first layer: 580 ml of silica dispersion B1 10% aqueous solution of polyvinyl alcohol (PVA203 manufactured by Kuraray Co., Ltd.) 5 ml aqueous solution of 5% polyvinyl alcohol (PVA235 manufactured by Kuraray Co., Ltd.) 250 ml Dispersion of fluorescent whitening agent (described below) 30 ml latex Dispersion (AE803, manufactured by Showa Kogyo Kogyo Co., Ltd.) 20 ml Ethanol 8.5 ml Pure water (to make the total amount 1000 ml) Coating solution for the second layer: Silica dispersion B1 620 ml Polyvinyl alcohol (Kuraray Co., Ltd. PVA203) 10% aqueous solution 5 ml 5% aqueous solution of polyvinyl alcohol (PVA235 manufactured by Kuraray Co., Ltd.) 270 ml Dispersion of optical brightener (described below) 30 ml Ethanol 3.5 ml Pure water (total volume is adjusted to 1000 ml) Coating solution for third layer: silica dispersion B1 630 l 10% aqueous solution of polyvinyl alcohol (PVA203 manufactured by Kuraray Co., Ltd.) 5 ml 5% aqueous solution of polyvinyl alcohol (PVA235 manufactured by Kuraray Co., Ltd.) 280 ml Fluorescent whitening agent dispersion liquid (described below) 10 ml ethanol 10 ml pure water (total volume is adjusted to 1000 ml) Coating solution for layer (top layer): silica dispersion B1 590 ml polyvinyl alcohol (PVA203 manufactured by Kuraray Co., Ltd.) 10% aqueous solution 5 ml polyvinyl alcohol (Pura235 manufactured by Kuraray Co., Ltd.) 5% aqueous solution 240 ml saponin aqueous solution (20%) 20 ml silicon emulsion ( (BY-22-839, manufactured by Dow Corning Toray Silicone Co., Ltd.) 45 ml ethanol 11 ml pure water (to make the total amount 1000 ml) Preparation of fluorescent brightener dispersion 3% acid-treated gelatin aqueous solution In 00L (a saponin 4k
g, containing 2 kg of cationic polymer P-1), an oil-soluble fluorescent whitening agent (UVITE) manufactured by Ciba-Geigy, Inc.
X-OB) 600 g and diisodecyl phthalate 12 kg
Was heated and dissolved in 25 L of ethyl acetate, and the mixture was emulsified and dispersed with a high-pressure homogenizer, and the total amount was adjusted to 140 L with pure water to prepare a fluorescent whitening agent dispersion.

The above coating solution was simultaneously coated on a paper support (thickness: 240 μm, glossiness at 75 ° of the coated surface of 30%) coated on both sides with polyethylene at the following wet film thickness, and the ink jet recording paper 1 was coated at the same time. Obtained.

First layer: 55 μm Second layer: 55 μm Third layer: 55 μm Fourth layer: 35 μm Coating was performed by simultaneously applying a coating solution at 40 ° C. and passing through a cooling zone at 0 ° C. for 20 seconds. Drying was performed by blowing air at ５０50 ° C. for 4 minutes.

When the section of the obtained recording paper was observed with a microscope, the dry film thickness was 32 μm in total from the first layer to the third layer, and the thickness of the fourth layer (uppermost layer) was about 7 μm.

Next, a coating solution was prepared by adding a matting agent having the composition of the exemplary matting agent M-1 to the fourth layer of the ink-jet recording paper 1 and applied in the same manner as the ink-jet recording paper 1 to form a four-layered ink. Inkjet recording papers 2 to 12 were prepared.

The following evaluation was performed on each of the obtained recording sheets.

Gloss: The glossiness of the recording surface was measured at 75 degrees using Nippon Denshoku Industries Co., Ltd. (VGS-1001DP).

Coefficient of friction: The coefficient of kinetic friction between the front and back of each recording sheet was measured.

Cracking: The number of cracks on the film surface after coating was examined and expressed as an amount per 0.5 m ² .

Paper feedability: 23 ° C., 80 ° C. using an ink jet printer, PM-750C manufactured by Epson Corporation.
%, 20 sheets were continuously fed, and this was repeated 10 times. The number of times paper was not fed or multiple paper feeding was performed was examined, and the number of times paper feeding was evaluated.

Scratch failure: A4 size recording paper was printed by an ink jet printer (PhotoSmart) manufactured by Hewlett-Packard Co., Ltd., and the abrasion on the surface during transportation was examined. The degree of abrasion was evaluated according to the following criteria.

◎: No scratches at all ：: One or two weak scratches are observed △: Weak streak on the entire surface but print quality is not significantly degraded ×: Strong scratches on entire surface, greatly deteriorating print quality Table 1 shows the above results.

[0103]

[Table 1]

As is clear from Table 1, the recording papers 2 to 5 and 7 to 12 in which the matting agent of the present invention was added to the protective layer were all supplied with the same high gloss as the comparative sample 1. It can be seen that the paper properties and the scratch resistance are improved.

On the other hand, the recording paper 6 using a matting agent having a degree of dispersion of 2 or more has improved paper feedability and scratch resistance, but has a large decrease in gloss, and has a quality that cannot be said to be glossy paper. .

Among the recording papers according to the present invention, those having a dispersity of 1 or less have particularly good glossiness.

Further, the glossiness of the recording papers 2 to 4, 7, 10, 11, and 12 using the matting agent in which the average particle size of the matting agent is larger than the dry film thickness (7 μm) of the uppermost layer by 2 μm or more is more excellent. You can see that.

On the other hand, in the case of recording paper in which the particle size of the matting agent exceeds 30 μm from the dry film thickness of the uppermost layer, the coating film surface has many cracks, and the number of scratches during printing has increased. Preferably, the particle size is not increased.

Comparative Example 1 Recording papers 1, 2, 10, 11, 12 prepared in Example 1
Recording paper (R1, R2, R10, R11, R1) in which each of the fourth layer coating solutions was applied in a single layer with a wet film thickness of 200 μm.
2) was produced.

The obtained recording paper was evaluated in the same manner as in Example 1, and the results shown in Table 2 were obtained.

[0111]

[Table 2]

As is clear from Table 2, when the void layer is formed as a single layer and a matting agent is added to this layer, the effect of improving the surface slipperiness is smaller than that of the present invention. Significant decrease in gloss.

Further, the number of cracks on the surface of the coating film is extremely increased. This is a condition in which coarse particles are mixed in a hard void layer. This is because cracks tend to occur more rapidly as coarse particles are present on the side closer to the support.

Example 2 Recording sheets 21 to 25 in which the amount of the matting agent added was changed as shown in Table 3 in the recording sheet 2 produced in Example 1.
Was produced in the same manner as in Example 1.

The number of particles of the matting agent is determined by measuring the aqueous solution of the matting agent dispersion having a known concentration using a particle counter (manufactured by Nozaki Sangyo Co., Ltd., Hiac / Leuco Intelligent Particle Counter 8000A), and the particle size is 2 μm Absolute numbers of the above were determined and measured.

[0116]

[Table 3]

As is evident from the results in Table 3, when the number of matting agents is in the range of 10 to 300 per m ² of recording paper, the decrease in gloss is particularly small, and the paper feedability is improved. .

Example 3 A recording sheet was prepared in the same manner as in Example 1 except that the wet film thickness of the recording sheet 2 prepared in Example 1 was changed as shown in Table 4.

The results shown in Table 4 were obtained in the same manner as in Example 1.

[0120]

[Table 4]

As is clear from the results shown in Table 4, as the dry thickness of the uppermost layer increases, the glossiness gradually decreases, and the friction coefficient also decreases. The dry thickness of the uppermost layer to which a particularly preferable matting agent is added is 1/3 or less of the dry thickness of all the void layers.

As described above, according to the present invention, it is possible to improve the paper feeding property and the transport property in the recording apparatus by improving the surface slipperiness without significantly lowering the gloss.

[0123]

According to the present invention, in an ink jet recording paper having a void layer composed of inorganic fine particles and a hydrophilic binder, the glossiness of the paper is not significantly reduced.
An ink jet recording paper having improved paper feedability and transportability inside the recording apparatus by improving the surface slipperiness could be provided.

Claims (1)

[Claims] 1. A support having a plurality of void layers containing inorganic fine particles and a hydrophilic binder on a support, wherein the uppermost layer of the void layers located farthest from the support has a dispersity of 2%.
An ink jet recording paper comprising the following monodisperse matting agent.