JP2006297819A - Ink jet recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet recording material having an excellent ink absorbency to enable high-speed recording, excellent in smoothness of an image recording part, high in image density, excellent in image uniformity, realizing high image quality in both dye ink and pigmented ink, excellent in scratch resistance on printed surface especially in pigmented ink, small in difference between white paper gloss and printed surface gloss printed in pigmented ink, and capable of being utilized for a photographing application, etc. <P>SOLUTION: In the ink jet recording material having at least two or more layer coating layers of first coating layers which contains a pigment a binder on a support and and second coating layers are set on a compatible ink jet recording material, the uppermost layer contains an ultrafine aggregate pigment having 0.008-0.7 μm of a mean particle diameter and a detailed aggregate pigment of 1-30 μm at a ratio of 100/1-100/15. Especially, if three or more sorts of colored pigments are contained in at least one-layer coating layers, ink jet printing paper approximating the color tone of a printing sheet is obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet recording material having good ink absorbability so that high speed recording is possible, excellent smoothness of an image recording portion, high image density, and extremely good image uniformity with both dye and pigment ink. It is. In particular, the present invention provides an ink jet recording material that can be used for printing, photographic use, etc., in which the printed portion has good rubbing property even with pigment ink, and the difference in printed portion gloss when printed with pigment ink is small.

  The ink jet recording method that ejects water-based ink from a fine nozzle toward the ink jet recording body to form an image on the surface of the ink jet recording body has low noise during recording, easy formation of a full color image, high speed It is widely used for photographs and various printing applications because it can be recorded and the recording cost is lower than other printing apparatuses.

  Particularly in recent years, high-definition and high-speed printers have made it possible to obtain images comparable to silver salt photography and plate-making multicolor printing. However, the quality of recorded images varies greatly depending on the recording medium, and the recording bodies are largely divided according to the purpose, such as for photographs, for printing, and for general offices.

  In order to achieve high image quality and high storage stability, the ink itself has been improved, and together with water-based dye inks (hereinafter referred to as dye inks) that use a highly hydrophilic colorant, which has been the mainstream, water resistance Ink (hereinafter referred to as “pigment ink”) in which a hydrophobic coloring pigment is dispersed, which has excellent properties and light resistance, has been put into practical use. There is a strong demand for a recording material that can realize high image quality for both the recording material, dye ink, and pigment ink. In particular, there is a strong demand for an ink jet recording material that can be used for printing, photographic use, etc., in which the printing portion has good rubbing properties even with pigment ink, and the difference in printing portion gloss when printed with pigment ink is small.

Various proposals have been made to realize image recording density, smoothness, and ink absorbability.
In order to achieve ink absorption, one or more layers are provided, the peak of the pore distribution curve of the uppermost layer is 0.2 to 10 μm, and the peak of the pore distribution curve of the entire ink receiving layer Is described in at least two locations of 0.2 to 10 μm and 0.05 μm or less (see, for example, Patent Document 1). Although the effect of improving the ink absorption speed is remarkable, in order to obtain such an ink jet recording material, it is indispensable that the coating layer (ink receiving layer) is designed mainly with a pigment having a particle diameter of 1 μm or more. In the case of a recording layer mainly composed of a pigment having a diameter of 1 μm or more, not only the gloss but also the image density is low and the roundness of the dots cannot be obtained, so the image uniformity is extremely low.

  In order to obtain gloss, print density, ink absorbency, and dot roundness, there have been attempts to use two or more types of fine pigments (both having a particle size of 1 μm or less) in the recording layer (see, for example, Patent Documents 2 and 3) ). If a fine pigment with a particle size of 1 μm or less is used, sufficient printing quality can be obtained with a dye ink. However, when a pigment ink is used, the scratch resistance of the pigment ink is insufficient, particularly when printing with white paper gloss and pigment ink. There is a problem that the difference in gloss of the printed part is so severe that it is difficult to use in photographic applications, particularly in printing applications where pigment ink is preferred.

  There was an attempt to use a fine pigment of 500 nm or less on a water-resistant support with a matting agent of 1 to 10 μm and a colored pigment of 1 μm or less for use in printing proofing (for example, see Patent Document 4). Receiving is basically performed with a single recording layer, so the solvent separation rate in the ink is slow, the scratching property of the pigment ink is insufficient, the print density is difficult to obtain, the color tone is not stable, and the print density is low. There was a difficult problem.

JP 58-110287 A JP 2004-174810 A JP 2003-2111825 A JP 2004-001449 A

  The present invention solves the above-mentioned problems and has good ink absorbability so that high-speed recording is possible, excellent image recording portion smoothness, high image density, and extremely good image uniformity. The present invention relates to an excellent ink jet recording material. In particular, the present invention provides an ink jet recording material that can be used for printing, photographic use, etc., in which the printed portion has good rubbing property even with pigment ink, and the difference in printed portion gloss when printed with pigment ink is small.

As a result of intensive studies in order to solve the above problems, the present inventors have found that this can be achieved by adopting the following configuration, and have reached the present invention.
[1] In an inkjet recording body having at least two coating layers of a first coating layer and a second coating layer containing a pigment and a binder on a support, the outermost layer has an average particle size of 0.008 to An ink jet recording material comprising an ultrafine aggregate pigment selected from 0.7 μm of silica, alumina and alumina hydrate and a matting pigment of 1 to 30 μm in a ratio of 100/1 to 100/15.

The present invention includes the following aspects.
[2] The ink jet recording material according to [1], wherein at least one coating layer contains three or more colored pigments selected from blue, bio red, red, and yellow.
[3] The inkjet recording material according to [2], wherein the colored pigment is a dispersion having an average particle diameter of 10 μm or less, and a dispersion liquid of the dispersion contains a propylene glycol compound.
[4] The ink jet recording material according to any one of [1] to [3], wherein the outermost layer does not contain a colored pigment.
[5] The inkjet recording material according to any one of [1] to [4], wherein the first coating layer contains a silica colloid pigment and a latex binder.
[6] The ultrafine aggregate pigment contained in the outermost layer is dry silica, and the dry silica is obtained by mixing particles obtained by mixing a cationic compound with particles obtained by agglomeration of the cationic compound with a content of 0.00. The ink jet recording material according to any one of [1] to [5], wherein the particles are silica-cationic compound aggregate fine particles pulverized and dispersed in a range of 01 to 0.5 μm.
[7] Any one of [1] to [6], wherein the matted pigment of 1 to 30 μm contained in the outermost layer is added to the ultrafine aggregate pigment after being mixed / dispersed with the cationic compound. 2. An ink jet recording material according to 1.
[8] Whiteness measured by JIS P8148 on the surface of an ink jet recording material is 80 to 90%, perceptual chromaticity index a * measured by JIS P8722 is −1 to 2, and perceptual chromaticity index b * is −2. The inkjet recording material according to any one of [1] to [7], which is from 5 to 1.0.

In the present invention, an ink jet recording material having two or more coating layers has excellent surface smoothness, ink absorbability, image quality of recorded images of dyes and pigment inks, scratch resistance of pigment inks, color tone stability, and blank paper gloss. And an ink jet recording material having a small difference in gloss between the printed portions of the pigment ink. Further, by blending a colored pigment in the coating layer, it has the same whiteness and color tone as the printed coated paper, and is excellent as an inkjet paper that replaces the printing calibration paper and general printing paper.

  The present invention is an ink jet recording body having at least two coating layers of a first coating layer and a second coating layer containing a pigment and a binder on a support, and the outermost layer has an average particle size of 0.008. It contains an ultrafine aggregate pigment selected from silica, alumina, and alumina hydrate of .about.0.7 .mu.m and a matting pigment of 1 to 30 .mu.m in a ratio of 100/1 to 100/15. When there are only two coating layers, the second coating layer corresponds to the outermost layer, and in an n-layer configuration having two or more layers, the outermost layer is the nth coating layer.

The present invention is described in detail below.
(Support)
The support of the present invention may be either a gas permeable support or a non-air permeable support, and can be appropriately selected depending on the purpose of use and application. A gas-permeable substrate is preferably selected in order to separate the ink absorptivity, particularly the pigment and the solvent of the pigment ink more quickly, and to increase the pigment fixing property and the print density.
(Air-permeable support)
As the air-permeable support, paper such as high-quality paper, art paper, coated paper, cast coated paper, foil paper, craft paper, baryta paper, impregnated paper, vapor-deposited paper, and water-soluble paper is appropriately used.

The air-permeable support is composed mainly of wood pulp and a filler containing it as necessary.
As the wood pulp, various chemical pulps, mechanical pulps, regenerated pulps and the like can be used, and these pulps can be beaten by a beating machine in order to adjust paper strength, papermaking suitability, and the like. The pulp beating degree (freeness) is not particularly limited, but generally 250 to 550 ml (CS)
F: about JIS P8121). In order to improve smoothness, it is desirable to advance the beating degree. However, when recorded on paper, paper blur and recording image bleeding caused by moisture in the ink often gives better results if the beating is not advanced. . Accordingly, the freeness is preferably about 300 to 500 ml.

The filler is blended for the purpose of imparting opacity or adjusting the ink absorbability, and calcium carbonate, calcined kaolin, silica, titanium oxide and the like can be used. In particular, calcium carbonate is preferable because it becomes a base material with high whiteness and glossiness of the ink jet recording material is enhanced. The content (ash content) of the filler in the paper substrate is preferably about 1 to 20% by mass, and if it is too much, the paper strength may be reduced. If the amount is too small, the air permeability of the paper base material is deteriorated. Therefore, a preferable filler content is 7 to 20% by mass. Within this range, the smoothness, air permeability, and paper strength are balanced, and as a result, an ink jet recording material with excellent smoothness can be easily obtained.

A sizing agent, a fixing agent, a paper strength enhancer, a cationizing agent, a yield improving agent, a dye, a fluorescent brightening agent, and the like can be added to the air-permeable support as an auxiliary agent. Furthermore, in the size press process of the paper machine, starch, polyvinyl alcohol, cationic resin and the like can be applied and impregnated to adjust the surface strength, sizing degree, and the like. The steecht degree (as 100 g / m ² paper) is preferably about 1 to 200 seconds. If the sizing degree is low, there may be operational problems such as wrinkling at the time of coating, and if it is high, the ink absorbability may be lowered, and curling and cockling after printing may be remarkable. A more preferred range of sizing is 4 to 120 seconds. Although the basic weight of a base material is not specifically limited, It is about 20-400 g / m < ² >. The range of 50 to 150 g / m ² is particularly preferable for printing applications. A range of 60 to 120 g / m ² is most preferred.

(Non-permeable support)
Examples of non-air-permeable supports include films such as polyethylene, polypropylene, soft polyvinyl chloride, hard polyvinyl chloride, polyester (including synthetic paper), metal foils, fine paper, art paper , Coated paper, cast coated paper, foil paper, kraft paper, impregnated paper, vapor-deposited paper, water-soluble paper, etc. and resin-coated paper in which a thermoplastic resin such as polyolefin is laminated to non-woven fabric, paper or non-woven fabric in films For example, laminated sheets and the like bonded together. As a preferable support, a so-called synthetic paper typified by YUPO (manufactured by YUPO Corporation) obtained by stretching polypropylene and specially processing, or a resin obtained by laminating a paper base material with a polyolefin resin (preferably a polyethylene resin) A coated paper is mentioned. The non-air-permeable support is slow in the separation rate of the dye or pigment in the ink and the solvent, but is effective in applications where cockling is a concern because the ink solvent does not penetrate into the substrate.

  Synthetic paper is usually obtained by extruding a polypropylene resin containing an inorganic pigment such as calcium carbonate and biaxially stretching to form voids in the interior. Among them, a laminated sheet composed of a plurality of layers is preferable. In particular, it is preferable to use a synthetic paper having a skin layer having no unevenness on the surface on which the recording layer is formed. Various layers such as an anchor layer, a primer layer, and an antistatic layer may be formed on the surface of the synthetic paper in order to improve coating suitability or chargeability.

  Among them, a resin-coated paper is particularly preferable because a support obtained by coating a polyethylene resin kneaded with titanium oxide on the surface of the paper is substantially the same as a photographic printing paper. The thickness of the polyethylene resin layer is preferably 3 to 50 μm, more preferably 5 to 30 μm. When the thickness of the polyethylene resin layer is less than 3 μm, defects such as holes in the polyethylene resin tend to increase during resin coating, and there are many cases where it is difficult to control the thickness, and it is difficult to obtain smoothness. Conversely, if it exceeds 50 μm, the effect obtained is small and uneconomical for an increase in cost.

  The paper base material used for the resin-coated paper is manufactured using wood pulp as a main material. As the wood pulp, various chemical pulps, mechanical pulps, regenerated pulps and the like can be used as appropriate, and these pulps can be adjusted in the beating degree by a beating machine in order to adjust paper strength, smoothness, papermaking suitability, and the like. The beating degree is not particularly limited, but generally about 250 to 550 ml (CSF: JIS P8121) is a preferable range. Also, chlorine-free pulp such as so-called ECF and TCF pulp can be preferably used. Moreover, a pigment can be added as needed. As the pigment, talc, calcium carbonate, clay, kaolin, calcined kaolin, silica, zeolite and the like are preferably used. Opacity and smoothness can be increased by adding a pigment, but if added excessively, paper strength may be reduced, and the amount of pigment added is preferably about 1 to 20% by mass with respect to wood pulp.

  Moreover, you may give an adhesion | attachment process or an adhesion | attachment process previously in order to improve the adhesiveness of a base material and a coating layer to the surface which forms a coating layer with a base material. In particular, when resin-coated paper is used as the substrate, it is preferable to subject the surface of the resin-coated layer to a corona discharge treatment or to provide an undercoat layer made of gelatin, polyvinyl alcohol or the like.

(Outermost layer)
The outermost layer of the present invention comprises an ultrafine aggregate pigment selected from silica, alumina and alumina hydrate having an average particle size of 0.008 to 0.7 μm and a matted pigment of 1 to 30 μm in a ratio of 100/1 to 100 /. It is contained at a ratio of 15.

The purpose, configuration, and formation method of providing the outermost layer will be described.
The purpose of the outermost layer is to quickly fix the dyes and pigments in the ink to obtain a high color (high printing density) and a uniform image (dot roundness). The pigment contains an ultrafine aggregate pigment selected from silica, alumina, and alumina hydrate having an average particle diameter of 0.008 to 0.7 μm and a matting pigment of 1 to 30 μm in a ratio of 100/1 to 100/15. By doing so, it is possible to obtain a highly colored and uniform image. In particular, even with pigment ink, the rubbing property of the printing part is good, and the difference between the glossiness of the printing part when printing with the blank paper and the pigment ink can be suppressed small. It can be used for photographs, print proofing, and inkjet paper that replaces general printing paper.

In order to obtain high image quality and suitability for pigment ink (image-containing uniformity, scratch resistance), the outermost layer of the present invention preferably has no cracks in the coating film. That is, it is preferable to control the pigment and the binder to be a continuous film. One way to control cracking is to thicken or crosslink the coating before the outermost layer is applied and during the drying of the formed coating layer and before the coating layer exhibits a reduced rate of drying. To form a film.
In the present invention, there is no particular limitation on the method of thickening or cross-linking the coating material at the same time as application or in the course of drying the formed coating layer and before the coating layer exhibits a reduced rate of drying. Contains a hydrophilic resin that forms a hydrogel by electron beam irradiation, immediately after coating, and during the drying of the formed coating layer, before the coating layer exhibits a reduced rate of drying. Irradiation method to thicken the coating layer (form hydrogel), the outermost layer contains polyvinyl alcohol, immediately after coating, and during the drying of the formed coating layer, Before the layer exhibits a decreasing rate of drying, a method of thickening and crosslinking the coating with a compound having crosslinkability with polyvinyl alcohol, a temperature-sensitive polymer as a binder (a constant temperature described in JP-A-2003-40916) (Temperature Sensitive Point) Including the hydrophilicity in the temperature range below and hydrophobic in the temperature range higher than the temperature sensitive point), the coating layer is thickened by lowering the coating temperature immediately after coating. The method is preferably selected.

(Pigment for outermost layer)
Examples of the ultrafine aggregate pigment selected from silica, alumina, and alumina hydrate having an average particle diameter of 0.008 to 0.7 μm used for the outermost layer include, for example, dry silica, mesoporous silica, and colloidally dispersed silica seed solution. After adding alkali to the seed solution, a secondary silica dispersion obtained by growing silica fine particles by adding a small amount of at least one feed liquid selected from an aqueous solution of active silicic acid and alkoxysilane to the seed solution, alumina, and At least one selected from alumina hydrate. Of these, vapor-phase method silica and alumina are preferable from the viewpoint of the film formability of the coating layer and the image density after printing.

Vapor phase silica used in the present invention is also called fumed silica, and is generally produced by flame hydrolysis. Specifically, a method of making silicon tetrachloride by burning with hydrogen and oxygen is generally known, but silanes such as methyltrichlorosilane and trichlorosilane can be used alone or silicon tetrachloride instead of silicon tetrachloride. Can be used in a mixed state.
The mesoporous silica used in the present invention is a porous silica material having an average pore diameter of 1.5 to 100 nm. In addition, mesoporous silica into which aluminum, titanium, vanadium, boron, manganese atoms or the like are introduced can also be used. The physical properties of the porous body are not particularly limited,
The BET specific surface area (nitrogen adsorption specific surface area) is preferably 200 to 1500 m ² / g, and the pore volume is preferably 0.5 to 4 cc / g. The method for synthesizing mesoporous silica is not particularly limited, but is described in U.S. Pat. No. 3,556,725, in which a quaternary ammonium salt containing a long-chain alkyl is used as a template. A quaternary ammonium salt having a long-chain alkyl group, using amorphous silica powder or alkaline silicate aqueous solution described in Table 5-5503499 as a silica source,
Alternatively, a hydrothermal synthesis method using a phosphonium salt as a template, a layered silicate such as kanemite as a silica source described in JP-A-4-238810, and an ion exchange method using a long-chain alkylammonium cation as a template And a method of synthesizing using active silica obtained by ion exchange of water glass or the like as a silica source using an amine such as dodecylamine or hexadecylamine, a nonionic surfactant or the like as a template. Examples of the method for removing the template from the nanoporous silica precursor include a method of baking at a high temperature and a method of extracting with an organic solvent.

After adding alkali to the colloidally dispersed silica seed solution used in the present invention, a silica fine particle is grown by adding a small amount of at least one feed solution selected from active silicic acid aqueous solution and alkoxysilane to the seed solution. The secondary silica dispersion obtained can be obtained by the method described in JP-A-2001-354408.
The alumina used in the present invention is generally called crystalline alumina oxide having crystallinity. In general, alumina oxide having χ, κ, γ, δ, θ, η, ρ, pseudo γ, and α crystals can be mentioned. In the present invention, gas phase method alumina oxide and alumina oxide having γ, δ, and θ crystals are preferably selected from the viewpoint of gloss and ink absorbability. Vapor phase alumina oxide (fumed alumina) having a sharp particle size distribution and particularly excellent film formability is most preferred. Vapor phase alumina is alumina formed by high temperature hydrolysis of gaseous aluminum trichloride, resulting in the formation of high purity alumina particles. The primary particle size of these particles is nano-order, and shows a very narrow particle size distribution (size distribution). Such vapor phase alumina oxide has a cationic surface charge. The use of vapor phase alumina in ink jet coating is shown, for example, in US Pat. No. 5,171,626.
The alumina hydrate used in the present invention is not particularly limited, but boehmite or pseudoboehmite is preferably selected from the viewpoint of ink absorbability and film formability. The method for producing alumina hydrate includes, for example, a method of hydrolyzing aluminum isopropoxide with water (BE Yoldas, amer. Ceram. Soc. Bull., 54, 289 (1975), etc.) and aluminum alkoxide. And a method of decomposing (Japanese Patent Laid-Open No. 06-064918).

  The ultrafine aggregate pigment selected from silica, alumina, and alumina hydrate having an average particle size of 0.008 to 0.7 μm is formed by agglomerating primary particles having an average primary particle size of 0.003 to 0.04 μm. It is preferable. In order to easily fix the dye or pigment in the ink to the outermost layer and to obtain the ink absorption rate, image density, and gloss, primary particles having an average primary particle diameter of 0.005 to 0.020 μm aggregate. A pigment having an average particle diameter of 0.01 to 0.5 μm is more preferable. More preferably, the pigment has an average particle diameter of 0.02 to 0.2 μm formed by agglomerating primary particles having an average primary particle diameter of 0.007 to 0.013 μm. In order to obtain an average particle size of 0.008 to 0.7 μm, for example, it is possible to obtain a strong force by mechanical means, that is, a so-called breaking down method (a method of subdividing a bulk material). Mechanical means include: ultrasonic homogenizer, pressure homogenizer, liquid collision homogenizer, high-speed rotary mill, roller mill, container drive medium mill, medium agitator mill, jet mill, mortar, disintegrator (covered in a bowl-shaped container) And a mechanical method such as a sand grinder or the like. Classification and repeated pulverization are necessary to reduce the particle size.

  In general, since the dyes and pigments in the ink are anionic, in order to further fix the dyes and pigments, silica, alumina, and alumina water having the average particle diameter of 0.008 to 0.7 μm may be used as necessary. A cationizable compound is added to an ultrafine aggregate pigment selected from Japanese. In particular, since the silica type is anionic, addition of a cationic compound is desired. Although the addition method is not particularly limited, for example, when a cationic compound is added to silica, alumina, or alumina hydrate having an average particle size of 0.008 to 0.7 μm, and aggregation or thickening does not occur at all. If it is lightly dispersed so as to be uniform, there is no problem. However, when aggregation or thickening occurs after addition, it is effective to pulverize and disperse using the breaking down method. Of course, there is also a method in which an aggregate pigment of silica, alumina, or alumina hydrate is added to a cationic compound solution and pulverized and dispersed so as to have an average particle size of 0.008 to 0.7 μm.

  From the standpoint of both ink absorbability and image density, the ultrafine aggregate pigment of the present invention is preferably dry silica. In particular, it is desirable to use particles obtained by mixing a cationic compound with dry silica and agglomerated particles of silica and a cationic compound. Dry silica-cationic compound aggregate fine particles having an average particle diameter in the range of 0.01 to 0.5 μm are most preferably used.

(Cationic compound)
Examples of the cationic compound used in the present invention include the following.
1) Polyalkylene polyamines such as polyethylene polyamine and polypropylene polyamine, and derivatives thereof 2) Acrylic resin having secondary amino group, tertiary amino group, and / or quaternary ammonium group 3) Polyvinylamine Polyvinylamidines, 5-membered cyclic amidines 4) Dicyan cationic resins such as dicyandiamide-formalin polycondensates 5) Polyamine cationic resins such as dicyandiamide-diethylenetriamine polycondensates 6) Epoxychlorohydrin-dimethylamine addition polymerization things 7) dimethyldiallylammonium chloride -SO ₂ copolymer 8) diallylamine -SO ₂ copolymer 9) dimethyldiallylammonium chloride polymer 10) polymer of allyl amine salt 11) dialkylamino ethyl (Meth) acrylate quaternary ammonium salt polymer 12) Acrylamide-diallylamine salt copolymer 13) Polyaluminum salts such as polyaluminum chloride, polyaluminum acetate, and polyaluminum lactate Among these, 1) 5-membered ring amidines, 2) It is preferable to use aluminum salts such as polyaluminum chloride, polyaluminum acetate, and polyaluminum lactate.
Among these, a cationic polymer is preferable from the viewpoint of dispersibility, and a cationic resin having primary, secondary, and tertiary amine groups is particularly preferable because of good dispersibility and print storage stability. Amidine compounds forming a 5-membered ring are the best.
The molecular weight of the cationic polymer is not particularly limited, but is preferably 10,000 to 100,000 in view of dispersibility and dispersion stability. More preferably, it is 20,000 to 70,000. If the molecular weight is too small, the dispersibility is poor, and if the molecular weight is too large, the dispersion stability may be inferior.
In addition, it is preferable that it is 1-30 parts with respect to 100 parts of pigments (solid content), and, as for the compounding quantity of a cationic compound, it is more preferable that it is 2-15 parts.

Matting pigments of 1-30 μm are gas phase method silica, wet method silica, colloidal silica, mesoporous silica, alumina, alumina hydrate, alumina silicate, kaolin, clay, calcined clay, zinc oxide, tin oxide, magnesium sulfate, water Various known and publicly known in the general coated paper field such as aluminum oxide, calcium carbonate, satin white, aluminum silicate, smectite, zeolite, magnesium silicate, magnesium carbonate, magnesium oxide, diatomaceous earth, styrene plastic pigment, urea resin plastic pigment, etc. A pigment is used. Wet silica and alumina are preferably selected in order to reduce the difference in ink absorbency, pigment rubbing property, glossiness of blank paper and printed portion gloss when printed with pigment ink. Wet silica is most preferred.
If the average particle size of the matted pigment is 1 to 30 μm, there is no problem, but in order to reduce the difference between the gloss of the printed part when printing with white paper and the pigment ink while maintaining the smoothness of the printed part of the pigment ink. A range of 1.5 to 15 μm is preferable, and a most preferable range is 2 to 5 μm.

The blending ratio of the ultrafine aggregate pigment selected from silica, alumina, and alumina hydrate having an average particle size of 0.008 to 0.7 μm to the matted pigment of 1 to 30 μm is 100/1 to 100/15. is there. Preferably it is the range of 100 / 1.5-100/10. The most preferred range is 100 / 2.5 to 100/6. When it is 100/1 or less, the pigment rubbing property is insufficient, and there is a problem that the difference in gloss of the printed portion particularly when printing with a blank paper gloss and pigment ink is conspicuous. When the ratio is 100/15 or more, the pigment rubbing property is saturated and there is a problem of image quality deterioration.
When the matting pigment is previously dispersed in the cationic compound and then added to the ultrafine aggregate pigment, a uniform dispersion can be obtained without causing aggregation or thickening. In the surface layer obtained by coating with a coating material containing such a dispersion, the matted pigment is uniformly distributed, and the uniformity of the image, particularly the uniformity of the printed image portion of the pigment ink, is excellent.

(Binder for outermost layer)
A conventionally well-known thing is mentioned as a binder contained in the outermost layer. For example, polyvinyl alcohol, polyvinylpyrrolidone, casein, soy protein, synthetic proteins, starch, carboxymethylcellulose, cellulose derivatives such as methylcellulose, polymer latex (emulsion type, solvent type, solventless type), water dispersion of synthetic resin emulsion, etc. Adhesives, temperature sensitive polymers and the like. From the viewpoint of adhesiveness to the pigment, polyvinyl alcohol is preferably the main component. Further, polyvinyl alcohol having a polymerization degree of 2000 or more is preferable from the viewpoint of ink absorbability and crack control, and polyvinyl alcohol having a polymerization degree of 3500 or more and a saponification degree of 95% or more is more preferable. Polyvinyl alcohol having a polymerization degree of 4000 or more and a saponification degree of 97% or more is most preferable. Two or more types of binders may be used in combination in order to improve ink absorbability.

For the purpose of improving the film formability (cracking control), a method of adding a compound having crosslinkability with polyvinyl alcohol to gel the coating film is effective. The content of the compound having crosslinkability with polyvinyl alcohol is 0.001 to 10 parts by mass, preferably 0.01 to 5 parts by mass, more preferably 0.05 to 1 part by mass with respect to 100 parts by mass of polyvinyl alcohol. It is. If the amount is too small, it is difficult to obtain a crosslinking effect. If the amount is too large, the coating film becomes too hard and the coating layer may be easily broken.
It is preferable to use a compound having a crosslinking property with polyvinyl alcohol as appropriate. The addition method of the compound having crosslinkability is not particularly limited. For example, a method of adding directly to the outermost layer coating, a coating layer in contact with the outermost layer, or coating the outermost layer after coating. Examples thereof include a method, a method of coating and impregnating a compound solution having crosslinkability after the outermost layer coating and before the coating layer exhibits a decreasing rate of drying.
Compounds having crosslinkability with polyvinyl alcohol include, for example, aldehyde-based crosslinking agents such as glyoxal, epoxy-based crosslinking agents such as ethylene glycol diglycidyl ether,
Examples thereof include vinyl-based crosslinking agents such as bisvinylsulfonylmethyl ether, and boron-containing compounds such as aluminum alum, boric acid and borax. In the present invention, a boron-containing compound having an excellent hardening effect is particularly preferable, and among these, borax is more preferable.

(Pigment / Binder ratio (PB ratio))
If the PB ratio of the outermost layer is in the range of 3 to 10, there is no problem, and the range of 4 to 8 is preferable and the range of 4 to 7 is more preferable from the balance of ink absorbability and coating film strength. If the PB ratio is less than 3, the ink absorption rate cannot be controlled, and beading may occur. If the PB ratio exceeds 10, the strength of the coating film is remarkably lowered and the practicality is lost.

The coating amount of the outermost layer is not particularly limited, but is adjusted to about ² to 40 g / m ² , preferably 3 to 15 g / m ² . If the amount is too small, the fixing ability of the dye or pigment, which is a color material in the ink, is insufficient, and if too much, the effect is saturated.

  Various auxiliary agents such as dispersants, thickeners, antifoaming agents, colorants, antistatic agents, preservatives and the like used in the production of general coated paper are appropriately added to the outermost layer.

(Coating layer other than the outermost layer)
When this invention is comprised by two coating layers, an outermost layer is a 2nd coating layer and coating layers other than an outermost layer are 1st coating layers. When the coating layer is composed of two or more layers and n layers, the outermost layer is an n layer, and the other coating layers are coating layers other than the outermost layer. The coating layer other than the outermost layer contains a pigment and a binder. Due to the multilayer structure, the coating layer other than the outermost layer quickly separates the solvent from the dye or pigment, and the color stability {so-called ΔE = (ΔL ² + Δa ² + Δb ² ) ^1/2 } and the printing density of the pigment ink are good. is there.

(Pigment for coating layer other than outermost layer)
Pigments used for coating layers other than the outermost layer are gas phase method silica, wet method silica, colloidal silica, mesoporous silica, alumina, alumina hydrate, alumina silicate, kaolin, clay, calcined clay, zinc oxide, tin oxide, sulfuric acid Known in the general coated paper field such as magnesium, aluminum hydroxide, calcium carbonate, satin white, aluminum silicate, smectite, zeolite, magnesium silicate, magnesium carbonate, magnesium oxide, diatomaceous earth, styrene plastic pigment, urea resin plastic pigment, etc. Various official pigments are used.
Particularly, commercially available wet silica, colloidal silica, kaolin, alumina, clay, calcined clay, and calcium carbonate are preferable from the viewpoint of the smoothness of the recording medium and the separation rate of the ink solvent. Most preferably, it contains wet silica aggregate particles having an average secondary particle diameter of 1 μm or less, colloidal silica, and kaolin. Two types of combination are also effective if necessary.
(Binder for coating layer other than outermost layer)
A conventionally well-known thing is mentioned as a binder contained in a coating layer. For example, polyvinyl alcohol, polyvinylpyrrolidone, casein, soy protein, synthetic proteins, starch, carboxymethylcellulose, cellulose derivatives such as methylcellulose, polymer latex (emulsion type, solvent type, solventless type), water dispersion of synthetic resin emulsion, etc. Adhesives, temperature sensitive polymers and the like. In particular, the latex of the coating layer adjacent to the surface layer is preferably a polymer latex in consideration of the strength of the coating film and the effect of the coating film becoming brittle with the crosslinking agent contained in the surface layer. Among these, it is preferable that an emulsion type latex is a main component in view of dispersion stability of the paint. More preferred are acrylic emulsion type latex, urethane emulsion type latex and SBR latex from the viewpoint of coating film strength and paint stability. It is the most desirable form to contain a silica colloid pigment and a latex binder from the balance of surface smoothness, solvent separation rate, and coating film strength.

If the PB ratio of the coating layer other than the outermost layer is in the range of 1 to 8, there is no problem, and the range of 2 to 7 is preferable from the balance of solvent absorption and coating strength, and the range of 2.5 to 6.5 is preferable. Further preferred.
If the PB ratio is less than 1, the solvent absorption rate is slow, and if it exceeds 8, the strength of the coating film may be significantly reduced.

The coating amount of the coating layer other than the outermost layer is not particularly limited, but is adjusted to about ² to 30 g / m ² , preferably 5 to 20 g / m ² . If it is less, the solvent separation function is insufficient, and if it is more, the effect is saturated.

Various auxiliary agents such as a dispersant, a thickener, an antifoaming agent, a colorant, an antistatic agent, and an antiseptic used in general coated paper production are appropriately added to the coating layer other than the outermost layer. Further, since a very small amount of dye is fixed as the solvent is absorbed, a cationic compound may be added and used for fixing the dye.

  The product of the present invention is particularly preferably used as an ink jet paper to replace printing proofing and printing paper. In order to use print proofing or ink jet paper instead of printing paper, the whiteness of the surface of the recording medium measured by JIS P8148 is 80 to 90%, the perceptual chromaticity index a * is −1 to 2, and the perceptual chromaticity It is desirable that the index b * is adjusted to −3 to 1.5. The most preferable range is whiteness of 83 to 88%, perceptual chromaticity index a * of 0 to 1.5, and perceptual chromaticity index b * of −2.5 to −1. In order to satisfy the white paper hue, at least one coating layer contains three or more colorants from blue, violet, red, and yellow. As the colorant, a color pigment is preferably used from the viewpoint of storage stability.

(Color pigment)
Examples of coloring pigments include water-soluble azo pigments, water-insoluble azo pigments, condensed azo pigments, phthalocyanine pigments, titanium black, titanium yellow, ultramarine blue, cobalt blue, carbon black, iron black, zinc oxide, participating cobalt, and aluminum hydroxide. However, it is not limited to this. Moreover, a white pigment can also be used for the purpose of improving the whiteness and adjusting the color tone. Examples include clay, calcined clay, calcium carbonate, magnesium carbonate, titanium dioxide, zeolite, kaolin, calcined kaolin, barium sulfate, magnesium silicate and other inorganic pigments, polystyrene resins, polycarbonate resins and other organic pigments. It is done.

Hue adjustment is often performed with only two types, but if at least three types are selected from blue, bio red, red, and yellow, a hue close to that of printing paper can be easily obtained.
It is preferable to mix the hue adjusting color pigment in a layer other than the surface layer. Since the outermost layer of the present invention has transparency, it is desired that the colored pigment for hue adjustment is placed in a layer other than the surface layer from the viewpoint of storage stability. As described in JP-A-2004-001449, when placed in the surface layer, the storage stability is inferior, and since the outermost layer uses a fine pigment, the transparency is high, and even if there is a patch of coating amount even a little There is a problem that color spots of white paper are likely to occur. If a coloring pigment is added to the outermost layer, not only the transparency is inhibited, but also the dispersibility of the paint may be lowered. In order to adjust the white paper hue without preservability and unevenness, it is preferable to add a colored pigment to the coating layer adjacent to the outermost layer.
The colored pigment is preferably added to the paint as a dispersion. The particle size of the colored pigment in the dispersion is preferably 10 μm or less, more preferably 2 μm or less, from the viewpoint of color development and storage. The most preferred range is 0.04 to 0.5 μm. When dispersing colored pigments, propylene glycol is most effective from the balance of dispersibility, environment and safety.

  It is also possible to provide a back layer for the purpose of improving curling and transportability.

  In order to further increase the gloss, a so-called casting method, which is obtained by pressure bonding to a heated mirror drum and drying while the outermost layer is in a wet state, is effective.

(Coating device and coating method)
Coating devices for obtaining the outermost layer and the coating layer other than the outermost layer include blade coaters, air knife coaters, roll coaters, bar coaters, gravure coaters, rod blade coaters, lip coaters, curtain coaters, and die coaters. Various known coating apparatuses can be mentioned. Of course, when two or more layers are applied, it is preferable to apply by wet on wet, which is a method of applying the upper layer on the lower layer while the lower layer is not dried.

(Calendar processing)
By smoothing at least one of the coating layers with a calendar, it is possible to improve the unevenness of the surface of the ink jet recording body and improve the glossiness and smoothness of appearance. The calendar pressure is preferably 30 to 250 kg / cm, and more preferably 50 to 180 kg / cm. If the calender pressure is lower than 30 kg / cm, the smoothing effect cannot be obtained. If the calender pressure is higher than 250 kg / cm, the coating layer is excessively crushed and the ink absorbability is inhibited.
(Average particle size)
The particle diameter of the aggregate pigment referred to in the present invention is a number average particle diameter. Immediately after stirring and dispersing a 5% dispersion with a homomixer at 2000 rpm for 30 minutes, the dispersion is applied to prepare a sample, and an electron microscope ( Observation with SEM and TEM), taking an electron microscope photograph of 10,000 to 400,000 times, and measuring and averaging the diameter of the secondary particles in a 5 cm square (“Particle Handbook”, Asakura Shoten, p52) 1991).

(ink)
As the ink used in the ink jet recording method of the present invention, a dye (dye, pigment) for forming an image and a liquid medium for dissolving or dispersing the dye are essential components, and various dispersants are used as necessary. It is adjusted by adding a surfactant, a viscosity modifier, a specific resistance modifier, a pH adjuster, a fungicide, and the like.

As the colorant used in the ink, there are a dye system and a pigment system. For example, there are various water-soluble dyes such as direct dyes, acid dyes, basic dyes, reactive dyes, edible dyes, disperse dyes, and oil-based dyes in the dye system. Examples thereof include carbon black surface-treated with an agent, organic pigments, and the like, and conventionally known ones can be used without particular limitation. The content of the dye or pigment is determined depending on the kind of the solvent component of the ink, the characteristics required for the ink, etc., but the ink used in the present invention is also similar to that in the conventional ink. There is no particular problem with blending, that is, use of about 0.1 to 20% by mass.

Examples of the solvent for the ink used in the present invention include water and various water-soluble organic solvents such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, and isobutyl alcohol. Alkyl alcohols, ketones such as acetone and diacetone alcohol, or polyalkylene glycols such as polyethylene glycol and polypropylene glycol, ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, tetraethylene glycol, thiodi Alkylene glycols having 2 to 6 alkylene groups such as glycol, hexylene glycol and diethylene glycol, amides such as dimethylformamide, tetrahydrofuran, etc. Ethers, glycerine, ethylene glycol methyl ether, diethylene glycol methyl (ethyl) ether, trimethylol propane, 1
, 2-hexanediol, lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl ether and triethylene glycol monoethyl ether, and pyrrolidones such as N-methyl-2-pyrrolidone.
In particular, the pigment ink contains 1,2-hexanediol and glycerin as water-soluble organic solvents in the pigment ink, and the sum of both is 80% or more of the water-soluble solvent, and the combination of the recording material of the present invention. However, it is suitable in terms of scratch resistance.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. Moreover, unless otherwise indicated, the part and% in an example are solid content except water, and show a mass part and mass%, respectively.

[Silica fine particle A]
Gas phase method silica having an average particle size of 1.0 μm (product name: Aerosil A3, manufactured by Nippon Aerosil Co., Ltd.)
00, average primary particle size: about 0.008 μm), and then dispersed with a sand grinder and further dispersed with a pressure homogenizer. Dispersion operation of the sand grinder and pressure homogenizer until the average particle size becomes 0.08 μm Was repeated to prepare a 10% aqueous dispersion. After adding 10 parts of a cationic compound having a 5-membered ring amidine structure (trade name: SC-700, molecular weight: 300,000) having a 5-membered ring amidine structure to the 10% aqueous dispersion and dispersing with a sand grinder, a pressure homogenizer Then, the dispersion operation of a sand grinder and a pressure homogenizer was repeated until an average particle size became 0.15 μm, thereby preparing a 10% aqueous dispersion.

[Silica fine particle B]
Gas phase method silica having an average particle size of 1.0 μm (manufactured by Nippon Aerosil Co., Ltd., trade name: Aerosil A300, average primary particle size: about 0.008 μm) Cationic compound having a 5-membered ring amidine structure in a 10% aqueous dispersion 10 parts (manufactured by Hymo Co., Ltd., trade name: SC-700, molecular weight: 300,000) is added, dispersed with a homomixer, and dispersed until the average particle size becomes 0.9 μm to prepare a 10% aqueous dispersion. did.

Example 1
[Coating fluid A]
4 parts of matted pigment (wet precipitated silica with an average particle size of 1.5 μm, manufactured by Tokuyama, trade name: Fine Seal F-80) are mixed and dispersed in 100 parts of silica fine particles A, and polyvinyl alcohol (manufactured by Kuraray Co., Ltd. (Product name: PVA-135, polymerization degree: 3500, saponification degree: 98.5%) 18 parts were mixed to prepare an 8% dispersion.
[Coating fluid B]
40 parts of an acrylic emulsion latex was mixed with 100 parts of a wet gel silica (Grace, trade name: 703A) having a particle size of 0.3 μm to prepare a 20% dispersion.
[Preparation of inkjet recording material]
Base paper (manufactured by Oji Paper Co., Ltd., marshmallow 104.7 g / m @ 2), the coating so that the amount of applying the coating liquid B is 15 g / ^{m 2,} dried, smoothed and 100 kg / cm pressure applied by calendering To obtain a first coating layer. Wet on Wet (2) so that the coating amount of 4% borax aqueous solution is 0.15 g / m ² and the coating amount of coating solution A is 10 g / m ² on the first coating layer. In the case of coating more than one layer, the outermost layer was coated and dried under the conditions of the method of coating the upper layer on the lower layer while the lower layer was not dried, and the outermost layer was obtained to prepare an ink jet recording material.

Example 2
[Coating fluid C]
10 parts of a cationic compound having a 5-membered ring amidine structure (product name: SC-700, molecular weight: 300,000) having a 5-membered ring amidine structure was added to 100 parts of the matted pigment of Example 1 and dispersed therein, and a 10% dispersion liquid was added. (1) was adjusted. 4 parts of dispersion (1) is added and dispersed in 100 parts of silica fine particles A, and 18 parts of polyvinyl alcohol (made by Kuraray Co., Ltd., trade name: PVA-135, polymerization degree: 3500, saponification degree: 98.5%) as a binder. Were mixed to prepare an 8% dispersion.
An ink jet recording material was produced in the same manner as in Example 1 except that the coating liquid A was changed to the coating liquid C in Example 1.

Example 3
An ink jet recording material was produced in the same manner as in Example 2 except that the wet precipitation silica having a particle size of 1.5 μm was changed to 3 μm wet precipitation silica in Example 2.

Example 4
An ink jet recording material was prepared in the same manner as in Example 2, except that the wet precipitation silica having a particle size of 1.5 μm was changed to 15 μm wet precipitation silica in Example 2.

Example 5
An ink jet recording material was prepared in the same manner as in Example 2 except that the wet precipitation silica having a particle size of 1.5 μm was changed to 25 μm wet precipitation silica in Example 2.

Example 6
In Example 2, an ink jet recording material was prepared in the same manner as in Example 2 except that the outermost silica fine particle A was changed to alumina (product name: PG-003, manufactured by CABOT) having a particle size of about 0.2 μm. did.

Example 7
In Example 2, the outermost silica fine particle A was changed to alumina hydrate having a particle size of about 0.5 μm (trade name: AS-3, manufactured by Catalyst Kasei Co., Ltd.). A recording body was produced.

Example 8
In Example 2, a wet gel silica having a particle size of 0.3 μm is made of kaolin (manufactured by Engelhard, trade name: Ultra White 90, average particle size 0.5 μm, oil absorption 46 ml / 100 g, specific surface area 14 m ² / g). An ink jet recording material was produced in the same manner as in Example 2 except that the above was changed.

Example 9
In Example 2, the wet gel method silica having a particle size of 0.3 μm was changed to colloidal silica (manufactured by Nissan Chemical Co., Ltd., trade name: Snowtex ST-YL, particle size: 0.065 μm). Thus, an ink jet recording material was produced.

Example 10
In Example 2, 100 parts of wet gel method silica having a particle size of 0.3 μm in the first coating layer was mixed with 50 parts of wet gel method silica having a particle size of 0.3 μm, kaolin (trade name: Ultra White, manufactured by Engelhard) 90, an average particle diameter of 0.5 μm, an oil absorption of 46 ml / 100 g, and a specific surface area of 14 m ² / g) An ink jet recording material was prepared in the same manner as in Example 2 except that the mixture was changed to 50 parts.

Example 11
In Example 10, with respect to 100 parts of the pigment of the first coating layer, 0.02 part of a blue color pigment (manufactured by Toyo Ink, trade name: EMT Blue DS18), a violet color pigment (manufactured by Toyo Ink, (Product name: EMT Violet BE) An ink jet recording material was produced in the same manner as in Example 10 except that 0.05 part was blended.

Example 12
In Example 10, with respect to 100 parts of the pigment of the first coating layer, 0.02 part of a blue color pigment (manufactured by Toyo Ink, trade name: EMT Blue DS18), a violet color pigment (manufactured by Toyo Ink, An ink jet recording material was prepared in the same manner as in Example 10 except that 0.04 part of a trade name: EMT violet BE) and 0.02 part of a yellow color pigment (manufactured by Toyo Ink Co., Ltd., trade name: EMT Yellow 5G) were blended. did.

Example 13
In Example 10, with respect to 100 parts of the pigment of the first coating layer, 0.02 part of a blue colored pigment (manufactured by Toyo Ink, trade name: EMT Blue DS18), a red colored pigment (manufactured by Toyo Ink, An ink jet recording material was prepared in the same manner as in Example 10, except that 0.04 part of a trade name: EMT Red KBS) and 0.02 part of a yellow color pigment (manufactured by Toyo Ink, trade name: EMT Yellow 5G) were blended. did.
Example 14
In Example 10, with respect to 100 parts of the outermost layer pigment, 0.02 part of a blue colored pigment (manufactured by Toyo Ink, trade name: EMT Blue DS18), a violet colored pigment (manufactured by Toyo Ink, trade name: EMT) An ink jet recording material was prepared in the same manner as in Example 10 except that 0.04 part of violet BE) and 0.02 part of yellow colored pigment (trade name: EMT Yellow 5G, manufactured by Toyo Ink Co., Ltd.) were blended.
(Comparative example)

Comparative Example 1
Base paper (manufactured by Oji Paper Co., Ltd., marshmallow 104.7 g / m @ 2), the coating amount of 4% borax solution is 0.15 g / ^{m 2,} the coating amount of the coating liquid A is 15 g / ^{m 2} As described above, coating and drying were performed under the conditions of Wet on Wet to prepare an ink jet recording material.

Comparative Example 2
An ink jet recording material was produced in the same manner as in Example 1 except that the matted pigment was omitted.

Comparative Example 3
An ink jet recording material was produced in the same manner as in Example 1 except that the silica fine particles A were changed to the silica fine particles B in Example 1.

Comparative Example 4
An ink jet recording material was produced in the same manner as in Example 1, except that the silica fine particles A were changed to colloidal silica silica (trade name: ST-YL, manufactured by Nissan Chemical Co., Ltd.) having an average particle size of 0.065 μm. .

Comparative Example 5
An ink jet recording material was prepared in the same manner as in Example 1, except that the matted pigment was changed to silica having an average particle diameter of 0.8 μm (obtained by pulverizing and dispersing the matted pigment of Example 1). did.

Comparative Example 6
An ink jet recording material was produced in the same manner as in Example 1 except that the matted pigment was changed to wet precipitation silica having an average particle size of 35 μm in Example 1.

Comparative Example 7
An ink jet recording material was produced in the same manner as in Example 1 except that the matted pigment was changed to 0.8 part in Example 1.

Comparative Example 8
An ink jet recording material was prepared in the same manner as in Example 1 except that the matting pigment was changed to 16 parts in Example 1.

[Evaluation Method 1]
About Examples 1-14 and Comparative Examples 1-8, the surface smoothness of the obtained ink jet recording material, ink absorptivity, image quality of recorded images of dye and pigment ink, scratch resistance of pigment ink, gloss of blank paper and pigment ink The gloss difference on the printed part was evaluated by the following method.
[Printer]
Dye inkjet printer: manufactured by Epson, model: PM-G800, printing in photo paper clean mode.
Pigment inkjet printer: manufactured by Epson Corporation, model: PX-6000, PX-MC photographic paper (thick and fine gloss) printing.

(Smoothness of blank paper)
The tested recording medium was judged visually and textured and evaluated according to the following three levels.
◯: Smooth feeling equal to or higher than gloss coated paper Δ: Smooth feeling equivalent to dull mat coated paper ×: Smooth feeling equal to or lower than dull mat paper.

(Ink absorption)
The sample recording medium was subjected to green and blue solid printing with the above two types of printers, and the ink absorptivity was visually observed and evaluated by the following methods.
○: The ink absorption speed is fast, and there is no ink overflow or beading.
Δ: Some beading is recognized, but there is no practical problem.
×: Ink overflow and beading.

(Recorded image quality)
The black solid print portion was measured with a Macbeth reflection densitometer (Macbeth RD-920), and the print density was measured.

(Friction of pigment ink)
The printed portion (black solid) of the pigment ink was rubbed with a cotton swab immediately after printing and evaluated by the following method.
○: Ink is not taken out and there is no problem Δ: Ink is taken out slightly, but there is no problem in practical use ×: Ink is taken out, practically problematic level

(Gloss difference between white paper gloss and pigment ink printing)
The gloss of the pigment ink printing part (solid printing of each color) and the blank paper part was visually observed and evaluated by the following method.
○: Level with almost no gloss difference Δ: Level with gloss difference but not significant ×: Large gloss difference

ΔE (tone stability)
ΔE (refer to “New edition Color Chemistry Handbook” (2nd edition), published by the University of Tokyo Press, p257 (1998))) 24 hours after the pigment ink printing portion (cyan solid portion) was measured. ΔE should be as small as possible, but if it is 3 or less, a change in color tone is generally unknown.

[Evaluation Method 2]
About Examples 10-14, printed matter (ISO-400 image, “high-definition color digital standard image data ISO / JIS-SCID”, p13, image name: fruit and basket) obtained with a white paper and pigment inkjet printer, Evaluation was carried out using coated paper for printing A2 gloss coated paper (manufactured by Oji Paper Co., Ltd., OK top coat + 127.9 g / m ² ) and its offset printed matter (the above image). The results are summarized in Table 2.
(Blank hue)
The hue tendency is shown in Table 2 in comparison with the blank hue of A2 gloss coated paper.
(Whiteness, perceived chromaticity index)
The whiteness of the surface of the test inkjet recording material was measured by the method of JIS P8148, the perceptual chromaticity index a *, and the perceptual chromaticity index b * were measured by the method of JIS P8722.
(Blank paper storage)
The recording surface of the ink jet recording material was placed on a desk in a general office and left for 3 months, and the change in the white paper hue was visually evaluated.

As is apparent from Table 1, the ink jet recording material of the present invention has excellent surface smoothness, ink absorbability, image quality of recorded images of dyes and pigment inks, excellent scratch resistance of pigment inks, color tone stability, and white paper gloss. This is an ink jet recording material having a small difference in gloss of the printed portion of the pigment ink.
Further, as apparent from Table 2, the ink jet recording material of the present invention has a good appearance and has the same whiteness and color tone as those of the coated paper by adding a colored pigment. It is also excellent as an inkjet paper that replaces paper.

The present invention provides an ink jet recording material that has good ink absorbability so that high-speed recording is possible, excellent smoothness of an image recording portion, high image density, and excellent dye and pigment inks with excellent image uniformity. can do.

Claims (8)

  In an ink jet recording body having at least two coating layers of a first coating layer and a second coating layer containing a pigment and a binder on a support, the outermost layer has an average particle size of 0.008 to 0.7 μm. An ink jet recording material comprising an ultrafine aggregate pigment selected from silica, alumina, and alumina hydrate of 1 to 30 μm in a ratio of 100/1 to 100/15.   2. The ink jet recording material according to claim 1, wherein at least one coating layer contains three or more colored pigments selected from blue, violet, red, and yellow.   The ink jet recording material according to claim 2, wherein the colored pigment is a dispersion having an average particle diameter of 10 µm or less, and the dispersion of the dispersion contains a propylene glycol compound.   The ink jet recording material according to claim 1, wherein the outermost layer does not contain a colored pigment.   The inkjet recording body according to any one of claims 1 to 4, wherein the first coating layer contains a silica colloid pigment and a latex binder.   The ultrafine aggregate pigment contained in the outermost layer is dry silica, and the dry silica is obtained by mixing particles obtained by mixing the cationic compound with particles of the cationic compound and 0.01 to 0. The ink jet recording material according to claim 1, which is fine particles of silica-cationic compound aggregates pulverized and dispersed in a range of 0.5 μm.   The inkjet recording material according to any one of claims 1 to 6, wherein the 1 to 30 µm matted pigment contained in the outermost layer is added to the ultrafine aggregate pigment after being mixed / dispersed with a cationic compound. The whiteness measured by JIS P8148 is 80 to 90%, the perceptual chromaticity index a * measured by JIS P8722 is −1 to 2, and the perceptual chromaticity index b * is −2.5 to It is 1.0, The inkjet recording body in any one of Claims 1-7.