JP2003054120A - Ink jet recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording medium being free of cracking of the surface of an ink receiving layer and excellent in ink absorption. SOLUTION: In the ink jet recording medium having at least one ink receiving layer on a water-resistant substrate, the ink receiving layer contains at least inorganic particulates having an average primary particle diameter of 3-30 nm and a polyvinyl alcohol having a silanol group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet recording medium on which an image is formed by an inkjet printer. More specifically, the present invention relates to a good ink jet recording medium which is free from cracks on the surface of the ink receiving layer, has high gloss, and is excellent in ink absorption.

[0002]

2. Description of the Related Art An ink jet recording system is a device for recording images, characters, etc. by ejecting minute droplets of ink by various operating principles and adhering them to a recording sheet such as paper. Inkjet printers have features such as high-speed printing, low noise, high flexibility of recording patterns, and no need for development-fixing, and complex images can be formed accurately and quickly. In recent years, it has been rapidly popularized for various purposes, especially as a hard copy creating apparatus for image information such as characters and various figures created by a computer.

Further, in the ink jet recording system, it is easy to perform multicolor recording by using a plurality of ink nozzles. The multi-color ink jet recording method can obtain images comparable to multi-color prints and color photographs, and can be cheaper than printing technology or photographic technology for applications with a small number of copies. Is being widely used by.

In recent years, the fields of use of ink jet printers, which have received a great deal of attention, include the production of color proofs and the output of design images in the design field in the printing field where high image quality close to that of photographs is required. Further, it is also common practice to output characters and image information created by a computer to a transparent recording sheet using an inkjet printer and use this as an original for an overhead projector for presentations at conferences.

The properties required of the recording sheet used in such an ink jet recording system are that the surface of the ink receiving layer has a high gloss, the image density is high, the color reproducibility is good, and the ink absorbability is high. And high dot reproducibility.

As an ink jet recording medium having a high ink absorption rate and improved transparency and glossiness, an ink jet recording medium using inorganic fine particles has recently been disclosed. For example, an ink jet recording medium using alumina hydrate is disclosed in Japanese Examined Patent Publication No. 3-24906 and Japanese Patent Laid-Open No. 2-2.
No. 76671, No. 3-67684, No. 3-215
No. 082, No. 3-251488, No. 4-6798
No. 6, Dohei 4-263983 and Dohei 5-16517
Japanese Patent Laid-Open No. 60-204390 and Japanese Patent Laid-Open No. 63-25 disclose ink-jet recording media using silica.
2779, JP-A-1-108083, and 3-27.
No. 976, No. 5-278324, No. 8-2698
No. 93 and No. 10-81064.

Further, Japanese Examined Patent Publication No. 3-56552 and Japanese Unexamined Patent Publication No.
188287, Dohei 10-81064, Dohei 10-
No. 119423, Dohei 10-175365, No. 10-
No. 200306, No. 10-217601, No. 11-
No. 20300, Dohei 11-20306, Dodai 11-3
Japanese Patent No. 4481 discloses a technique for improving gloss and ink absorbability by using synthetic silica fine particles according to a vapor phase method (hereinafter referred to as vapor phase method silica).

By the way, it is also necessary to use a hydrophilic binder in the ink receiving layer in order to increase the strength of the film. However, forming an ink receiving layer having a void layer formed of inorganic fine particles on the support as described above is one of the effective means for increasing the ink absorbability of the recording material,
The amount used is limited so that the hydrophilic binder used in combination with the ultrafine inorganic particles does not block the void layer and lower the ink absorbability.

As described above, in order to efficiently increase the void volume, the ink receiving layer film coated and dried by using the minimum necessary amount of the hydrophilic binder with respect to the inorganic fine particles has a low film strength, and the ink receiving layer is coated and dried. After that, fine cracks are generated on the film surface, the gloss is reduced, and image bleeding occurs, resulting in a marked deterioration in image quality. In particular, when an ink receiving layer containing inorganic fine particles having an average particle size of 0.1 μm or less is provided, cracking is likely to occur.

It is known to use a hydrophilic binder and a cross-linking agent thereof together in order to prevent the cracks. Known cross-linking agents include, for example, epoxy compounds, aldehyde compounds, active halogen compounds, boric acid and its salts, borax, alum and the like. In particular, JP-A-1
Boric acid and its salts are preferably used as shown in 0-119423 and 7-76161.

However, these crosslinking agents generally have mutagenicity or skin irritation. Therefore, a substance that is not irreversibly released from the sheet after crosslinking is preferable in this respect, but there are many problems because, for example, the above boric acid is easily extracted with water even after crosslinking.

Further, as the support of the above-mentioned recording material,
Conventionally, paper is generally used, and the paper itself has a role as an ink absorbing layer. In recent years, as photo-like recording sheets have been demanded, recording sheets using a paper support have problems such as gloss, texture, water resistance, cockling (wrinkles or waviness) after printing, and are treated with water resistance. Also, a paper support such as a resin-laminated paper (polyolefin resin-coated paper) in which a polyolefin resin such as polyethylene is laminated on both sides of the paper has come to be used. However, since these water-resistant supports cannot absorb ink unlike the paper supports, the ink absorbability of the ink receiving layer provided on the supports is important, and therefore, the paper support is Compared to the recording material, the recording material of the water resistant support had to be coated with a large amount of pigment.
By increasing the coating amount of the pigment, cracks tended to occur during drying, and the quality was remarkably deteriorated.

On the other hand, the use of silanol-modified PVA as a binder for ink jet recording sheets is disclosed in JP-A-62-259882, JP-A-62-268682, JP-A-63-28889, JP-A-6-32046 and JP-A-6-32046. 9
No. 123,588 and No. 2000-15924. However, these are not intended to prevent cracking that occurs when a large amount of inorganic fine particles is used in order to improve ink absorbability.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording medium which does not have cracks on the surface of the ink receiving layer which could not be realized by the prior art, has excellent ink absorbency and does not adversely affect the environment. Is to do.

[0015]

The above-mentioned problems of the present invention have been basically solved by the following means. In an inkjet recording medium having at least one ink receiving layer on a water-resistant support, the ink receiving layer contains inorganic fine particles having an average primary particle diameter of at least 3 to 30 nm and a polyvinyl alcohol having a silanol group. Characteristic inkjet recording medium.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
As the inorganic fine particles used in the present invention, synthetic silica,
Alumina or its hydrate, calcium carbonate, barium sulfate, magnesium hydroxide and the like can be mentioned. Among them, synthetic silica is preferable, and vapor phase silica and alumina are particularly preferable.

Synthetic silica includes a wet method and a gas phase method. Usually, silica fine particles often refer to wet-process silica. As the wet process silica, silica sol obtained through metathesis of sodium silicate due to acid or the like or through an ion exchange resin layer, or colloidal silica obtained by heating and aging this silica sol, and gelation of silica sol, and changing the formation conditions thereof Silica gel, in which primary particles of several microns to 10 microns are siloxane-bonded to form three-dimensional secondary particles, and silica sol, sodium silicate, sodium aluminate, etc. are produced by heating. There is a synthetic silicic acid compound mainly containing an acid.

The vapor phase silica is also called a dry method as opposed to a wet method, and is generally produced by a flame hydrolysis method. Specifically, a method of burning silicon tetrachloride with hydrogen and oxygen is generally known, but instead of silicon tetrachloride, silanes such as methyltrichlorosilane and trichlorosilane may be used alone or in the form of silicon tetrachloride. It can be used as a mixture with. Vapor phase silica is commercially available as Aerosil from Nippon Aerosil Co., Ltd. and can be obtained.

The average particle diameter of the primary particles of vapor phase method silica which is particularly preferably used in the present invention is 30 nm or less, preferably 3 to 20 nm, and the specific surface area according to the BET method is 50 m ² / g or more, It is preferably 100 to 500 m ² / g. The BET method in the present invention is one of the surface area measurement methods for powders by the vapor phase adsorption method, and is a method for obtaining the total surface area of 1 g of a sample, that is, the specific surface area, from the adsorption isotherm. Nitrogen gas is often used as the adsorption gas,
The most commonly used method is to measure the amount of adsorption from the pressure or volume of the gas to be adsorbed. The most prominent of the isotherms for multimolecular adsorption are Brunauer, Emmett, and Teller.
Which is called the BET formula and is widely used for determining the surface area. The surface area is obtained by determining the adsorption amount based on the BET formula and multiplying the area occupied by one adsorbed molecule on the surface.

The characteristic feature of the vapor-phase process silica is that the primary particles exist in a state of being linked together in a network structure or in a chain form and secondarily aggregated, whereby high ink absorbability is obtained. The state of secondary aggregation is preferably maintained at about 50 to 500 nm, whereby high ink absorbency can be obtained without lowering gloss.

Alumina used in the present invention is fine particles having an average primary particle diameter of 30 nm or less. Alumina fine particles may be porous, and the shape thereof may be arbitrary, such as indefinite, acicular or spherical. The method for producing the alumina fine particles is not particularly limited, but the vapor phase method is preferable because it has few impurities and the average particle diameter is uniform.

The amount of the inorganic fine particles used depends on the required quality of the product, etc., but is 10 to 100 g / dry weight.
m ² , more preferably 12 to 50 g / m ² is used.

The polyvinyl alcohol having a silanol group used in the present invention is, for example, a radical copolymerization of an alkylene monomer having a silanol group with a lower fatty acid vinyl ester such as vinyl acetate, and the resulting copolymer is saponified. The polyvinyl alcohol-based polymer obtained by the method described above, etc., and preferably has a saponification degree of 85% or more and a polymerization degree of 500 or more and 2000 or less in view of water solubility, film-forming property, dissolution viscosity and the like. The silanol group content in the modified polyvinyl alcohol-based polymer having a silanol group in the molecule is 0.05 as a silanol group-containing monomer unit.
1.5 mol% is preferable, and if it is less than 0.05 mol%, curing that improves the coating strength cannot be obtained, and 1.5 mol%
If it exceeds the above range, the water solubility of the polymer is lowered, so that not only the ink absorbability of the ink receiving layer is lowered, but also the thickening of the coating liquid due to the interaction with the inorganic fine particles is remarkable and not practically preferable.

In the present invention, in addition to the above-mentioned polyvinyl alcohol having a silanol group, as a binder, etherified starch, cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, casein, gelatin, soybean protein, polyvinyl alcohol and its derivatives,
A maleic anhydride derivative, an ordinary styrene-butadiene copolymer or the like can be used.

Of these, polyvinyl alcohol and its derivatives are preferably used. From the viewpoint of preventing cracks, those having a high degree of polymerization are preferable, and those having a degree of polymerization of at least 2,000 or more, more preferably 3,000 or more,
More preferably, 4,000 or more are used.

The polyvinyl alcohol having a silanol group as described above is preferably used in combination with the above-mentioned other binder. The use amount of polyvinyl alcohol having a silanol group is 0.1% or more and 50% or less, and more preferably 0.5% or more and 20% or less by weight% with respect to the total binder. If too much is used, it causes excessive thickening of the coating liquid, which is not preferable.

The amount of the inorganic fine particles used is preferably 1 to 30 times the weight of all the binders used. It is more preferably 2 to 10 times.

In order to prevent cracking with less bander, the present invention preferably contains a compound containing a Group 4A element of the periodic table. Particularly preferred are those containing titanium or zirconium. These are preferably water-soluble. For example, titanium chloride, titanium sulfate, titanium lactate as the water-soluble compound containing titanium, zirconium acetate, zirconium chloride, zirconium oxychloride, zirconium hydroxychloride, zirconium nitrate, basic zirconium carbonate as the water-soluble compound containing zirconium.
Zirconium hydroxide, zirconium carbonate ammonium, zirconium carbonate potassium, zirconium sulfate,
Zirconium fluoride compounds and the like are known. Some of these compounds have an inappropriately low pH, and in that case, the pH can be adjusted appropriately before use.

In the present invention, a crosslinking agent (hardening agent) can be used together with the above hydrophilic binder. Specific examples of the cross-linking agent include aldehyde compounds such as formaldehyde and glutaraldehyde, ketone compounds such as diacetyl and chloropentanedione, bis (2-chloroethylurea) -2-hydroxy-4,6-dichloro-1, 3,5
Triazine, a compound having a reactive halogen as described in US Pat. No. 3,288,775, divinyl sulfone, a compound having a reactive olefin as described in US Pat. No. 3,635,718, US Pat. 732,3
N-methylol compounds as described in US Pat. No. 16, isocyanates as described in US Pat. No. 3,103,437, US Pat. Nos. 3,017,280 and 2,983,611.
Aziridine compounds as described in U.S. Pat.
Carbodiimide compounds such as those described in US Pat. No. 0,704, epoxy compounds such as those described in US Pat. No. 3,091,537, halogen carboxaldehydes such as mucochloric acid, dioxane derivatives such as dihydroxydioxane,
There are inorganic crosslinking agents such as chromium alum, zirconium sulfate, boric acid and borate, and these can be used alone or in combination of two or more.

However, as described above, many of the above-mentioned cross-linking agents generally have toxicity such as mutagenicity, and it is necessary to select one that does not dissolve out from the formed film.
Of these, it is preferable not to use boric acid or to use a smaller amount thereof.

The ink receiving layer of the present invention preferably further contains a cationic compound. Examples of the cationic compound include a cationic polymer and a water-soluble metal compound. Examples of the cationic polymer include polyethyleneimine, polydiallylamine, polyallylamine, alkylamii polymers, JP-A-59-20696, JP-A-59-33176, JP-A-59-33177, and JP-A-59-3177.
No. 9-155088, No. 60-11389, No. 6
0-49990, 60-83882, 60
-109894, 62-198493, 6
3-49478, Do 63-115780, Do 6
3-280681, JP-A-1-40371, 6
-234268, Dohei 7-125411, Dohei 10
Polymers having a primary to tertiary amino group and a quaternary ammonium base described in JP-A-193776 and the like are preferably used. The molecular weight of these cationic polymers is
It is preferably 5,000 or more, more preferably about 5,000 to 100,000.

Examples of the above-mentioned water-soluble metal compound include water-soluble polyvalent metal salts. Examples thereof include water-soluble salts of metals selected from calcium, barium, manganese, copper, cobalt, nickel, aluminum, iron, zinc, zirconium, chromium, magnesium, tungsten and molybdenum. Specifically, for example, calcium acetate, calcium chloride, calcium formate, calcium sulfate, barium acetate, barium sulfate, barium phosphate, manganese chloride, manganese acetate, manganese formate dihydrate, manganese ammonium sulfate hexahydrate, chloride chloride. Dicopper, ammonium chloride copper (II) dihydrate, copper sulfate, cobalt chloride,
Cobalt thiocyanate, cobalt sulfate, nickel sulfate hexahydrate, nickel chloride hexahydrate, nickel acetate tetrahydrate, nickel ammonium ammonium hexahydrate, nickel amidosulfate tetrahydrate, aluminum sulfate, aluminum sulfite, Aluminum thiosulfate, polyaluminum chloride, aluminum nitrate nonahydrate, aluminum chloride hexahydrate,
Ferrous bromide, ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, zinc bromide, zinc chloride, zinc nitrate hexahydrate, zinc sulfate, zirconium acetate, zirconium chloride, chloride Zirconium oxide octahydrate, zirconium hydroxychloride, chromium acetate, chromium sulfate, magnesium sulfate, magnesium chloride hexahydrate, magnesium citrate nonahydrate, sodium phosphotungstate, sodium citrate tungsten, 12 tungstophosphate n Hydrate, 12 tungstosilicic acid 26 hydrate, molybdenum chloride, 12 molybdophosphoric acid n hydrate and the like can be mentioned.

In the present invention, a water-soluble aluminum compound is particularly preferable in terms of water resistance, weather resistance and prevention of cracking of inorganic fine particles. As the water-soluble aluminum compound, for example, as an inorganic salt, aluminum chloride or its hydrate, aluminum sulfate or its hydrate, ammonium alum and the like are known. Further, there is a basic polyaluminum hydroxide compound which is an inorganic aluminum-containing cationic polymer. Particularly, a basic polyaluminum hydroxide compound is preferable.

These substances are used as water treatment agents under the name of polyaluminum chloride (PAC) from Taki Chemical Co., Ltd., under the name of polyaluminum hydroxide (Paho) from Asada Chemical Co., Ltd. It is marketed by Riken Green under the name Purachem WT and from other manufacturers for the same purpose, and various grades are easily available. In the present invention, these commercial products can be used as they are, but
Is unsuitably low, and in such a case, it is possible to adjust the pH appropriately before use.

In the present invention, the content of the water-soluble metal compound in the ink receiving layer is 0.1 to 10 g / m ² , preferably 0.2 to 5 g / m ² . These can be used together.

The ink receiving layer in the present invention may contain various oil droplets in order to improve the brittleness of the film. Such oil droplets include hydrophobic high-boiling organic solvents having a solubility in water at room temperature of 0.01% by weight or less (for example,
Liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicone oil, etc.) and polymer particles (for example, particles obtained by polymerizing one or more polymerizable monomers such as styrene, butyl acrylate, divinylbenzene, butyl methacrylate, hydroxyethyl methacrylate).
Can be included. Such oil droplets can be used preferably in the range of 10 to 50% by weight with respect to the hydrophilic binder.

In the present invention, a surfactant can be added to the ink receiving layer. The amount of the surfactant added was 0.10 with respect to 100 g of the binder constituting the ink receiving layer.
001-5g is preferable, More preferably, it is 0.01-3.
It is g.

In the present invention, the ink receiving layer further includes a coloring dye, a coloring pigment, a fixing agent for the ink dye, an ultraviolet absorber, an antioxidant, a pigment dispersant, a defoaming agent, a leveling agent, a preservative, and a fluorescent agent. Various known additives such as a whitening agent, a viscosity stabilizer, and a pH adjusting agent can also be added.

In the present invention, the coating method is not particularly limited, and a known coating method can be used. For example, there are a slide bead method, a curtain method, an extrusion method, an air knife method, a roll coating method, a ked bar coating method and the like.

The polyolefin resin-coated paper support (hereinafter referred to as resin-coated paper) used in the present invention will be described in detail. The resin-coated paper used in the present invention has a water content of 6% or more. It is preferably in the range of 6.5 to 9.0%, more preferably in the range of 7.0 to 9.0%. The water content of the resin-coated paper can be measured using an arbitrary water content measuring method. For example, an infrared moisture meter, an absolute dry weight method, a dielectric constant method, a Karl Fischer method or the like can be used.

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

Further, a surface sizing agent, a surface paper strength agent, a fluorescent whitening agent, an antistatic agent, a dye, an anchor agent, etc. may be applied on the surface.

The thickness of the base paper is not particularly limited, but a material having good surface smoothness obtained by compressing the paper by applying pressure with a calender during or after the papermaking is preferable, and its basis weight is 30 to 250 g / m ² is preferable.

The polyolefin resin coated on the base paper is a homopolymer of olefin such as low density polyethylene, high density polyethylene, polypropylene, polybutene, polypentene or a copolymer of two or more olefins such as ethylene / propylene copolymer. And mixtures of these, those having various densities and melt viscosity indexes (melt indexes) can be used alone or by mixing them.

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

The resin-coated paper is produced by a so-called extrusion coating method in which a polyolefin resin is cast on a running base paper in a molten state by heating, and both surfaces thereof are coated with the resin. Further, it is preferable that the base paper is subjected to activation treatment such as corona discharge treatment or flame treatment before the base paper is coated with the resin. It is not necessary to coat the resin on the back surface, but it is preferable to coat the resin from the viewpoint of preventing curling. The back surface is usually a matte surface, and the front surface or both front and back surfaces can be subjected to activation treatment such as corona discharge treatment and flame treatment as required. Further, the thickness of the resin coating layer is not particularly limited, but it is generally coated on the surface or both front and back sides with a thickness of 5 to 50 μm.

A common method for adjusting the water content of the resin-coated paper is to adjust the drying by a dryer when the base paper (paper base) is made into paper, or to provide a humidity control zone after completion of the drying. is there.

The resin-coated paper used in the present invention is preferably a finely roughened surface so that the surface of the polyolefin resin layer has a 75-degree specular gloss of 30% or more and less than 70% according to JIS-P8142. Polyolefin resin coated paper is made by heating and melting polyolefin resin with an extruder and extruding it into a film between the base paper and a cooling roll, press bonding,
Manufactured by cooling. At this time, the cooling roll is used to form the surface shape of the polyolefin resin coating layer, and the surface of the resin layer has a high gloss, a matte surface, or a patterned surface such as a silky or matte shape depending on the shape of the cooling roll surface. Etc. can be formed. In the present invention, a cooling roll having a slightly roughened surface is used, and the surface of the polyolefin resin layer on the side where the ink receiving layer is provided is provided with JIS.
-75 degree specular gloss according to P8142 30% or more 70
Be less than%. The gloss is preferably 35% or more and less than 70%, and more preferably 40% or more and 68.
% Or less.

In the present invention, the finely rough surface is not a mirror surface or a molded object such as a silk surface or a matte surface, but an object having extremely fine irregularities on the surface. For example, it can be represented by the center surface average roughness (SRa). This SRa value is preferably in the range of 0.11 to 0.50 μm, more preferably 0.11 to 0.35 μm, and even more preferably 0.1.
The range of 12 to 0.25 μm is preferable.

The center surface average roughness (SRa) is a cutoff value of 0. 0 measured by a stylus type three-dimensional surface roughness meter.
It is an SRa value at 8 mm and is defined by the following mathematical formula 1.

[0051]

[Equation 1] In Formula 1, Wx represents the length of the sample surface area in the x-axis direction, Wy represents the length of the sample surface area in the y-axis direction, and Sa represents the area of the sample surface area.

Specifically, as a stylus type three-dimensional surface roughness meter and three-dimensional roughness analyzer, SE-3A manufactured by Kosaka Laboratory Ltd.
Using a K-type machine and a SPA-11 type machine, the cutoff values are 0.8 mm, Wx = 20 mm, Wy = 8 mm,
It can be obtained under the condition of Sa = 160 mm ² .

The shape of the surface of the cooling roll used for the finely roughened surface is not particularly limited as long as it is finely roughened. For example, JP-A-5-118557, JP-A-7-261325 and JP-A-7-261325 can be used. 8-254789, Doppei 1
Cooling rolls such as those disclosed in JP-A No. 0-293379 and JP-B No. 62-19732 are used. For example, the surface has an average depth of 0.05 to 0.7 μm,
A cooling roll having fine irregularities with an average pitch of 0.1 to 100 μm is used.

A recording material having a high gloss, no cracks, and high ink absorbency is obtained by using a resin-coated paper having a specific water content and having a specific water content and a vapor-phase process silica, and further heating. can get.

The support in the present invention has an antistatic property,
Various back coat layers can be applied for transportability and curl prevention. The back coat layer may contain an inorganic antistatic agent, an organic antistatic agent, a hydrophilic binder, a latex, a curing agent, a pigment, a surfactant and the like in an appropriate combination.

[0056]

The present invention will be described in detail below with reference to examples, but the contents of the present invention are not limited to the examples. or,
Parts and% described below are parts by weight and% by weight, respectively.
Indicates.

Example 1 Preparation of Ink Receptive Layer <Preparation of Polyolefin Resin Coated Paper Support> A 1: 1 mixture of a bleached hardwood kraft pulp (LBKP) and a bleached softwood sulfite pulp (NBSP) was made up to 300 ml by Canadian standard freeness. It was beaten until it became a pulp slurry. Alkyl ketene dimer as a sizing agent to 0.5% by weight of pulp, polyacrylamide as a strength agent to 1.0% by weight of pulp, cationized starch to 2.0% by weight of pulp, and polyamide epichlorohydrin resin. 0.5% by weight of pulp was added and diluted with water to obtain a 1% slurry. This slurry was made into paper by a Fourdrinier paper machine so as to have a basis weight of 170 g / m ² , dried and conditioned to obtain a base paper for polyolefin resin-coated paper. Low-density polyethylene with a density of 0.918 g / cm ^{3 on} paper
A polyethylene resin composition in which 10% by weight of anatase-type titanium is uniformly dispersed in 32% by weight of the resin is 32%.
It was melted at 0 ° C., extrusion-coated to a thickness of 30 μm at 200 m / min, and extrusion-coated using a micro-roughened cooling roll. The other surface has a density of 0.
A blended resin composition of 70 parts by weight of 962 g / cm ³ high-density polyethylene resin and 30 parts by weight of low-density polyethylene resin having a density of 0.918 was melted at 320 ° C. in the same manner, and extrusion-coated to a thickness of 30 μm. The support thus obtained had an SRa value of 0.15 μm and a water content of 7.5%.
Met.

<Preparation of Ink Receiving Layer 1> An ink receiving layer coating solution having the following composition was applied to the above support by a slide coating apparatus and dried. The ink receiving layer coating liquid shown below was prepared so that the vapor phase silica had a solid content concentration of 9% by weight.
This coating liquid is 18 g when the coating amount of vapor-phase method silica is solid.
It was applied and dried so as to be / m ² . After drying, it was wound into a roll, which was further cut into A4 size and heated at 40 ° C. for 3 days.

<Ink Receptive Layer Coating Liquid> Vapor Phase Silica 1
00 parts (average primary particle size 12 nm, specific surface area by BET method 30
0m ² / g) Dimethyldiallylammonium chloride homopolymer 4 parts (Daiichi Kogyo Seiyaku Co., Ltd., Charol DC9)
02P, molecular weight 9000) Polyvinyl alcohol 23 parts
(Saponification degree 88%, average degree of polymerization 4500), silanol-modified polyvinyl alcohol (Kuraray Co., Ltd., R1130) 2
Department

<Preparation of ink receiving layer 2> Ink receiving layer 1
In place of the vapor phase silica used in the preparation of the vapor phase alumina fine particles (trade name: aluminum oxide C, Degussa.
It was obtained in the same manner except that 25 parts of Huls's average primary particle diameter 13 nm) was added.

<Preparation of ink receiving layer 3> Ink receiving layer 1
21 parts of polyvinyl alcohol and 2 parts of silanol-modified polyvinyl alcohol used in the preparation of were prepared. Further, the same procedure as in the above was carried out except that 0.5 part of ZC-2 (manufactured by Daiichi Rare Element Co., Ltd.) was added as a zirconium compound.

<Preparation of ink receiving layer 4> Ink receiving layer 3
Was obtained in the same manner except that 0.5 part of ORGATICS TC-310 (manufactured by Matsumoto Kosho Co., Ltd.) was added as a titanium compound instead of zirconium used in the preparation of.

<Preparation of ink receiving layer 5> Ink receiving layer 1
In the same manner as in Example 1, except that the polyvinyl alcohol used in the preparation was changed to 25 parts and the silanol-modified polyvinyl alcohol was not used.

<Preparation of ink receiving layer 6> Ink receiving layer 1
Was obtained in the same manner except that wet-phase silica (trade name: Fineseal X60, manufactured by Tokuyama Corp., particle size 5.5 to 6.5 μm) was used in place of the vapor-phase silica used in the preparation.

◎ Sample evaluation

The recording material produced as described above was evaluated for cracks and ink absorbency. The results are shown in Table 1. <Crack> Visual observation and observation with a magnifying glass of 50 times were performed and evaluated according to the following criteria. ⊚: No crack is observed even with a magnifying glass. ◯: No crack is visually observed. Δ: Minor cracks are observed when observed carefully. X: Cracks are observed on the entire surface. ○ The above is required as a product. <Ink absorbency> Plotter (Novajet-PRO4 manufactured by ENCAD
2E) and GS ink are used to print C, M, and Y, respectively, and immediately after printing, PPC paper is overlaid on the printing section and lightly pressed, and the degree of ink transferred to the PPC paper is visually observed. The following criteria evaluated. The results are shown in Table 1. ⊚: No transfer even when 200% of C, M, and Y are printed. ◯: When C, M, and Y are printed at 200%, a slight transfer occurs. Δ: When C, M, and Y are printed at 100%, a slight transfer occurs. X: When C, M, and Y are printed at 100%, respectively, they are considerably transferred. ○ The above is required as a product.

[0067]

[Table 1]

[0068]

As is apparent from the above examples, according to the present invention, it is possible to obtain an ink receiving layer having high ink absorbency without cracks.

Claims (6)

[Claims] 1. An ink jet recording medium having at least one ink receiving layer on a water resistant support,
The ink receiving layer has an average primary particle size of at least 3 to 30.
An inkjet recording medium containing inorganic fine particles of nm and polyvinyl alcohol having a silanol group. 2. The amount of the inorganic fine particles is 12 to 50 g / m ^2.
The inkjet recording medium according to claim 1, wherein 3. The ink jet recording medium according to claim 1, wherein the inorganic fine particles are vapor grown silica or alumina. 4. The ink jet recording medium according to claim 1, wherein the amount of the polyvinyl alcohol having a silanol group used is 0.1 to 50% by weight with respect to the amount of all binders used in the ink receiving layer. 5. The amount of the inorganic fine particles used is 1 to 30 by weight with respect to the amount of all binders used in the ink receiving layer.
2. The ink jet recording medium according to claim 1, which is double the number. 6. The inkjet recording medium according to claim 1, which contains a compound of Group 4A element of the periodic table.