JP2000326626A - Aqueous ink jet recording sheet, its manufacture, and powder paint therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous ink jet recording sheet capable of forming a clear image in a high density with excellent aqueous ink jet ink absorbency, its manufacture and a powder paint therefor. SOLUTION: In the aqueous ink jet recording sheet comprising an ink receptive layer 26 containing powder paint 23 fusion bonded to each other while having partial air gaps 24 therebetween on a base material 25, the powder paint 23 contains hydrophobic resin composition particles 21 contained in partial water soluble resin while exposing with its surface, and hydrophilic second inorganic fine particles 22 covering the surfaces of the composition particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous ink jet recording sheet, and more particularly, to an aqueous ink jet recording sheet having excellent absorbability of an aqueous ink jet ink and capable of forming a clear and high-density image and its production. And powder coatings therefor.

[0002]

2. Description of the Related Art Conventionally, various recording methods have been known. In recent years, aqueous ink-jet recording methods in which aqueous ink is ejected directly from nozzles onto recording paper and adhered thereto for recording have been widely used. Has reached.

[0003] Conventionally, this aqueous ink jet recording sheet is prepared by wet-coating a solution containing a water-soluble or water-swellable resin, a pigment and other additives onto a substrate, removing the solvent, and drying. Forming a layer comprising the resin layer in which the pigment is dispersed as an ink receiving layer, adsorbing the colorant in the ink to the pigment, and absorbing the water in the ink into the resin, An image is formed thereon. Accordingly, in such an ink jet recording sheet, the surface of the ink receiving layer is generally covered with a continuous resin layer, so that the ink jet ink has a low absorption property and the ink is inferior in drying property. Also,
There are also problems such as being limited to those having high water absorption. Further, according to the receiving layer as described above, the coloring property of the ink is not sufficient.

Further, from the viewpoint of manufacturing, such a conventional ink jet recording sheet is prepared by applying a coating liquid containing a resin, a pigment, and other additives onto a substrate by wet coating, drying the coating liquid, and drying the ink. Since the receiving layer is formed, when the solvent is removed, not only environmental considerations are required, but also the manufacturing cost of the recording sheet has to be increased.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems in the conventional aqueous ink jet recording sheet, and has an excellent absorbability of the aqueous ink jet ink, and has a clear and high density. It is an object of the present invention to provide an aqueous inkjet recording sheet capable of forming an image of the type described above, its production, and a powder coating material therefor.

[0006]

According to the present invention, there is provided an aqueous ink composition having a resin layer formed by fusing with each other as an ink receiving layer on a base material, while the powder coating has a partial gap therebetween. In the ink jet recording sheet, the powder coating,
A part of the water-soluble resin, while being exposed on the surface thereof, the hydrophobic resin composition particles contained therein, and the hydrophilic resin fine particles covering the surface of the hydrophobic resin composition particles may be composed of fine inorganic particles. An aqueous ink jet recording sheet characterized by the features is provided.

Further, according to the present invention, there is provided an aqueous ink jet recording sheet having a surface layer made of hydrophilic second inorganic fine particles on the resin layer.

Further, according to the present invention, the hydrophobic resin and the water-soluble resin are melt-kneaded and pulverized, so that the water-soluble resin is partially contained while being exposed on the surface of the hydrophobic resin particles. After forming the hydrophobic resin composition particles, the mixture is mixed with hydrophilic second inorganic fine particles, and the surface of the hydrophobic resin composition particles is coated with the hydrophilic second inorganic fine particles. A method for producing a powder coating material for an aqueous inkjet recording sheet is provided.

Further, according to the present invention, the hydrophobic resin composition particles contained and the surface of the hydrophobic resin composition particles are coated while partially exposing the water-soluble resin to the surface thereof. A powder coating comprising hydrophilic second inorganic fine particles is dry-coated on a substrate, and heated, so that the powder coating is fused to each other while having a partial gap therebetween. A method for producing an aqueous ink jet recording sheet, comprising forming a resin layer formed on a substrate as an ink receiving layer.

Further, according to the present invention, the hydrophobic resin composition particles contained and the surface of the hydrophobic resin composition particles are coated while partially exposing the water-soluble resin to the surface thereof. A powder coating comprising hydrophilic second inorganic fine particles is dry-coated on a substrate, and heated, so that the powder coating is fused to each other while having a partial gap therebetween. A water-based inkjet recording sheet, comprising: forming a resin layer formed on a base material; and forming a surface made of hydrophilic second inorganic fine particles on the resin layer. .

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the aqueous ink jet recording sheet according to the present invention will be described. This aqueous inkjet recording sheet is a water-based inkjet recording sheet having a resin layer formed on a substrate as an ink receiving layer on a substrate as an ink-receiving layer, while a powder coating material has a partial gap therebetween. The coating has a water-soluble resin that is partially exposed to the surface and contains an average particle diameter of 1
And a mean particle size of 1 nm to 1 μm covering the surface of the hydrophobic resin composition particles.
and hydrophilic inorganic fine particles of μm.

According to the present invention, the powder coating used for producing such an aqueous ink jet recording sheet is prepared by melt-kneading a hydrophobic resin and a water-soluble resin, and the resulting kneaded product has an average particle size of 1 to 30 μm. Pulverized to partially expose the water-soluble resin to the surface of the hydrophobic resin while forming hydrophobic resin composition particles having an average particle diameter of 1 to 30 μm. It can be obtained by mixing with 1 nm to 1 μm hydrophilic inorganic fine particles and coating the surface of the hydrophobic resin composition particles with the hydrophilic inorganic fine particles.

In the hydrophobic resin composition particles constituting such a powder coating, a part of the water-soluble resin is exposed on the surface of the hydrophobic resin particles. By providing water absorption, the ink receiving layer formed therefrom can be provided with ink absorbency and color development.

FIG. 1 schematically shows such powder coating composition particles. That is, the powder coating composition particles are composed of the water-soluble resin particles 11 and the hydrophobic resin 12, and a part of the water-soluble resin particles is exposed to the surface of the particles made of the hydrophobic resin. Is dispersed inside.

In the present invention, the above-mentioned hydrophobic resin is not particularly limited in a polymer material constituting the hydrophobic resin, but refers to a resin material having a deionized water absorption of 0.1 times or less of its own weight, Specific examples include, for example, a saturated polyester resin, a styrene-acrylic copolymer resin, an ethylene-vinyl acetate copolymer resin, a styrene-butadiene copolymer resin, and the like.

Commercial products can be suitably used as the saturated polyester resin. Such commercial products include, for example, Byron 103, 200, 290, 600
(Manufactured by Toyobo Co., Ltd.), KA-1038C (manufactured by Arakawa Chemical Co., Ltd.), TP-220, 235 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), Diacron ER-101, ER-50
1, FC-172, FC-344, FC-714 (manufactured by Mitsubishi Rayon Co., Ltd.), Tufton NE-382, 111
0, 2155 (manufactured by Kao Corporation) and the like.

The styrene / acrylic copolymer resin is a copolymer of styrene and (meth) acrylic acid ester. Specifically, the (meth) acrylic acid ester includes, for example, ethyl acrylate and butyl acrylate. , Methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate and the like.

As such a styrene-acrylic copolymer resin, various commercial products can be suitably used. Commercial products include, for example, Hymer UNi-3000, TB
-1800, TBH-1500 (Sanyo Chemical Industry Co., Ltd.)
CPR-100, 600B, 200, 300, X
PA4799, 4800 (manufactured by Mitsui Chemicals, Inc.) and the like.

In the present invention, such a hydrophobic resin is not particularly limited, but has a softening point of 70 to 70.
It is preferably in the range of 120 ° C.

In the present invention, examples of the water-soluble resin include polyvinyl alcohol, polyethylene oxide, polyethylene oxide-polypropylene oxide copolymer, hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, and polyvinylpyrrolidone. According to the present invention, such a water-soluble resin has a softening point of 40-1.
It is preferably in the range of 50 ° C., especially 50 to 12 ° C.
It is preferably in the range of 0 ° C.

The ratio of the water-soluble resin to the hydrophobic resin is usually in the range of 5 to 50% by weight.
Preferably, it is in the range of 10 to 30% by weight. When the ratio of the water-soluble resin to the hydrophobic resin is less than 5% by weight, the resulting hydrophobic resin composition particles do not have sufficient hydrophilicity, and the finally obtained ink jet recording sheet is an aqueous ink jet ink. Not sufficiently improved in absorbency. On the other hand, when the ratio of the water-soluble resin to the hydrophobic resin exceeds 50% by weight, the resulting hydrophobic resin composition particles have excessive hydrophilicity. When adhered, stickiness may occur and the image may be poor in sharpness.

According to the present invention, such a water-soluble resin is melt-kneaded together with the above-mentioned hydrophobic resin, cooled and then pulverized to have an average particle diameter of 1 to 30 μm, preferably 5 to 20 μm. Since the water-soluble resin has poor compatibility with the hydrophobic resin, the water-soluble resin is dispersed as fine particles in the kneaded material. Part, while being exposed on the surface of the hydrophobic resin, the hydrophobic resin composition particles having an average particle diameter of 1 to 30 μm can be obtained. That is, in the obtained hydrophobic resin composition particles, a water-soluble resin (island) is finely dispersed in a matrix (sea) of the hydrophobic resin, and a part thereof is exposed on the surface. The hydrophobic resin composition particles thus obtained are, as it were, particles composed of a sea-island resin composition having the hydrophobic resin as the sea and the water-soluble resin as the island.

Then, the average particle diameter is changed from 1 nm to 1 μm.
To obtain a powder coating in which the surface of the hydrophobic resin composition particles is coated with the hydrophilic inorganic fine particles.

In the present invention, the hydrophobic resin composition particles may contain additives such as a coloring agent and a filler, if necessary. The colorant is preferably white, and for example, titanium oxide is preferably used, but is not limited thereto. The colorant gives the substrate the required ground color. The white colorant gives the substrate a white ground color.
The coloring agent is usually 0.5 in the hydrophobic resin composition particles.
To 60% by weight, preferably 5 to 50% by weight. As the filler, for example, silica, calcium carbonate, or the like is used.

Furthermore, according to the present invention, when the hydrophobic resin composition particles are dry-coated on a substrate and then heated and melted to fix the particles on the substrate, an offset is caused. An anti-offset agent may be included, if necessary, so as not to cause any problem. As the anti-offset agent, usually, various waxes having a melting point in the range of 50 to 150 ° C. are preferably used. Specific examples include paraffin wax, polyolefin wax such as polyethylene and polypropylene, fatty acid metal salts, fatty acid esters, higher fatty acids, higher alcohols, and the like. Such an offset preventing agent is usually used in the powder coating composition in an amount of 0.1 to 20% by weight, preferably 0.5 to 10% by weight.
Used in the range.

As described above, the hydrophobic resin composition particles containing a colorant, a filler, and other additives together with the resin are mixed with each other, usually at about 100 to 200 ° C., preferably at 130 to 180 ° C. A few minutes at a moderate temperature, usually 3-5
It is obtained by melt-kneading for about a minute, cooling, pulverizing and classifying. The hydrophobic resin composition particles have an average particle diameter in the range of 1 to 30 μm, preferably 5 to 2 μm.
It is in the range of 0 μm.

The powder coating used in the production of the aqueous ink jet recording sheet according to the present invention is obtained by melting and kneading a hydrophobic resin and a water-soluble resin, usually at a temperature of about 100 to 200 ° C., and cooling. After pulverizing to have an average particle size of 1 to 30 μm to obtain hydrophobic resin composition particles,
This can be obtained by mixing this with hydrophilic inorganic fine particles having an average particle size of 1 nm to 1 μm, and coating the surface of the hydrophobic resin composition particles with the hydrophilic inorganic fine particles.

When the average particle size of the hydrophilic inorganic fine particles is larger than 1 μm, even if such inorganic fine particles are mixed with the hydrophobic resin composition particles and the hydrophobic resin composition particles are coated, It is difficult to uniformly coat the hydrophobic resin composition particles, and the ratio of the surface that is not coated with the hydrophilic inorganic fine particles increases, and as a result, the hydrophobic resin composition particles have sufficient hydrophilicity. In other words, it is difficult to form an ink receiving layer that is excellent in the absorbency and color development of the aqueous inkjet ink.

As such hydrophilic inorganic fine particles, commercially available products can be easily obtained. Specific examples of commercially available products include, for example, Aerosil (registered trademark) 50, 90G, 130, and 20 which are anhydrous silica manufactured by Nippon Aerosil Co., Ltd.
0, 200V, 200CF, 200FAD, 300, 3
00CF, 380, OX50, TT600, MOX8
0, MOX170, COK84, etc., aluminum oxide C, titanium dioxide P25, etc., anhydrous silica S13, V15, N20, T30, T40 manufactured by Clariant Japan.
And the like.

According to the present invention, such hydrophilic inorganic fine particles are used in an amount of 3 to 12 parts by weight, preferably 5 to 10 parts by weight, based on 100 parts by weight of the hydrophobic resin composition particles. Can be That is, with respect to 100 parts by weight of the hydrophobic resin composition particles, 3 to 12 parts by weight of hydrophilic inorganic fine particles are mixed to coat the surface of the hydrophobic resin composition particles, and this is used as a powder coating. By applying a dry coating on a substrate, heating and partially melting the powder coating, the powder coating is partially fused with each other while having a gap therebetween, and the powder coating is mutually fused. A resin layer having a gap therebetween can be formed on a substrate as an ink receiving layer. The voids between the powder coatings are usually in the range of 1 nm to 200 nm.

In the present invention, the thickness of such a resin layer is usually in the range of 2 to 80 μm, preferably in the range of 5 to 50 μm.

According to the present invention, the hydrophobic resin composition particles are dispersed and contained while exposing the water-soluble resin partially to the surface, and the hydrophobic resin composition particles are further formed. Since the powder coating whose surface is coated with hydrophilic inorganic fine particles forms the resin layer as the ink receiving layer, the surface of the resin layer is also coated with the hydrophilic inorganic fine particles.

Therefore, when the amount of the hydrophilic inorganic fine particles is less than 3 parts by weight based on 100 parts by weight of the hydrophobic resin composition particles, the surface of the hydrophobic resin composition particles is sufficiently covered by the hydrophilic inorganic fine particles. Since it is not coated, the surface of the ink receiving layer is also not sufficiently coated with the hydrophilic inorganic fine particles, so that the obtained inkjet recording sheet does not have sufficient coloring properties and cannot form a clear, high-density image. . On the other hand, when the hydrophilic inorganic fine particles are more than 12 parts by weight based on 100 parts by weight of the hydrophobic resin composition particles,
In particular, it is difficult for the hydrophobic resin composition particles to directly contact the substrate, and it is difficult to sufficiently fix the powder coating on the substrate even when the powder coating is heated.

FIG. 2 schematically shows a cross section of an embodiment of such an ink jet recording sheet according to the present invention. Each of the hydrophobic resin composition particles 21 partially disperses and contains a water-soluble resin (not shown) while exposing a water-soluble resin (not shown) on the surface thereof.
To form powder coatings 23, which are mutually fused and fixed on the base material 25, with a partial gap 24 therebetween, to form an ink receiving coating 23. A resin layer 26 is formed as a layer.

According to another preferred embodiment of the ink jet recording sheet according to the present invention, a surface layer comprising hydrophilic second inorganic fine particles is further provided on such a resin layer.
As the hydrophilic second inorganic fine particles, usually, the same hydrophilic first inorganic fine particles used in the preparation of the powder coating are used, and the type thereof is hydrophilic first inorganic fine particles. It need not be the same as the microparticle. Therefore, the hydrophilic second
The inorganic fine particles may have an average particle diameter in a range of 1 nm to 1 μm, and preferably have an average particle diameter of 1 nm to 5 μm.
0 nm, most preferably with an average particle size of 5 to 5 nm.
It is in the range of 30 nm.

The ink jet recording sheet provided with such an ink receiving layer having a two-layer structure is obtained by dry-coating the above-mentioned powder coating on a substrate, heating and fixing the resin coating as described above. Is formed, and then the hydrophilic second inorganic fine particles are dry-coated on the resin layer and heated under pressure to form a surface layer made of the hydrophilic second inorganic fine particles on the resin layer. The powder coating is fixed on the base material, thus forming a resin layer formed by fusing the powder coating composition on the base material with the voids partially interposed therebetween, and forming the hydrophilic layer on the resin layer. Can be obtained by forming a surface layer composed of the second inorganic fine particles. Such a resin layer and a surface layer work together as an ink receiving layer.

However, according to the present invention, if necessary,
The powder coating is dry-coated on a substrate to form a coating layer composed of the powder coating, and then the hydrophilic second inorganic fine particles are dry-coated on the coating layer of the powder coating. Coating to form a coating layer of hydrophilic second inorganic fine particles, and then heating these two coating layers under pressure, so that the powder coating on the substrate is in between It is also obtained by forming a resin layer which is partially fused and mutually fused while having voids, and by forming a surface layer made of the above-mentioned hydrophilic second inorganic fine particles on this resin layer. Can be.

FIG. 3 schematically shows a cross section of such an ink jet recording sheet. As in the embodiment shown in FIG.
Each hydrophobic resin composition particle 31 has a part on its surface,
The inorganic fine particles 3 are dispersed and contained while exposing a water-soluble resin (not shown), and have a hydrophilic surface.
2 to form powder coatings 33, which are mutually fused and fixed on the base material 35, with a void 34 therebetween, and A layer 36 is formed, and a surface layer 38 composed of hydrophilic second inorganic fine particles 37 is further formed on the resin layer, so that the ink receiving layer has a two-layer structure.

The average particle diameter of the second hydrophilic inorganic fine particles is 1
When larger than μm, when inkjet recording is performed on a recording sheet having a surface layer of such inorganic fine particles on the surface, an obtained image may lack accuracy, and an inkjet recording sheet giving a high quality image may be obtained. Can not get. On the other hand, the hydrophilic second inorganic fine particles may have an average particle size smaller than 1 nm, but it is sufficient to use those having an average particle size of 1 nm or more from the viewpoint of availability.

According to the present invention, the surface layer composed of the second inorganic fine particles may contain an appropriate binder and other additives. In particular, by incorporating a binder into the surface layer made of the second inorganic fine particles, the surface layer can be more firmly fixed to the resin layer. As the binder, various resins are used without any particular limitation. For example, a resin for forming the powder coating composition is used. Above all, the above-mentioned hydrophobic resin, water-soluble resin, or a mixture thereof is mixed as powder into the second inorganic fine particles, which is dry-coated on the resin layer, and heated to form the second inorganic fine particles. Are pressed together on the resin layer while being bonded to each other by the binder, and are firmly adhered and fixed on the resin layer. The binder is used in an amount of usually 1 to 200 parts by weight, preferably 5 to 100 parts by weight, based on 100 parts by weight of the second inorganic fine particles.

However, according to the present invention, the surface layer composed of the second inorganic fine particles may be formed by wet coating, if necessary, instead of the above-mentioned dry coating.
That is, the second inorganic fine particles are dispersed in a medium, preferably an aqueous medium such as water, and a binder, for example, a water-soluble resin is added thereto to prepare a coating liquid, which is then ink-received. The surface layer made of the second inorganic fine particles can also be formed on the resin layer by drying after coating on the resin layer as a layer. When the powder coating composition forming the resin layer is not dissolved or swollen, a non-aqueous medium may be used in place of the aqueous medium in some cases.

In the image receiving sheet for ink jet recording thus obtained, the resin layer has a thickness of usually 1 to 100 μm, preferably 2 to 8 μm, as described above.
0 μm, particularly preferably in the range of 5 to 50 μm, and the surface layer composed of the second inorganic fine particles is usually in the range of usually 10 nm to 10 μm,
Preferably it is in the range from 20 nm to 5 μm.

As described above, in the ink jet recording sheet having the surface layer made of the hydrophilic second inorganic fine particles on the receiving layer, when the ink jet ink adheres to the ink jet recording sheet, the colorant in the ink becomes Is captured by the surface layer of the second inorganic fine particles, so that a clear and high-density image is formed. On the other hand, the water in the ink is quickly filtered by the surface layer composed of the hydrophilic second inorganic fine particles. And penetrates into the receiving layer, is quickly adsorbed in the gap between the powder coatings, is absorbed by the water-soluble resin of the hydrophobic resin particles, and is also adsorbed by the hydrophilic inorganic fine particles on the surface thereof. .

According to the present invention, when the surface layer composed of the hydrophilic second inorganic fine particles is formed on the receiving layer as described above, the powder coating for forming the receiving layer comprises the above-mentioned average coating composition. The surface of 100 parts by weight of the hydrophobic resin composition particles having a particle diameter of 1 to 30 μm may be coated with 3 to 12 parts by weight, preferably 5 to 10 parts by weight of hydrophobic inorganic fine particles. Further, the powder coating for forming the receiving layer, the surface of 100 parts by weight of the hydrophobic resin composition particles having an average particle size of 1 to 30 μm, the surface of the second hydrophilic inorganic fine particles and the hydrophobic inorganic fine particles. 3 to 12 parts by weight of the mixture, preferably 5 to
It may be one coated with 10 parts by weight.

According to such an ink jet recording sheet, when the ink jet ink adheres to the ink jet recording sheet, the colorant in the ink is captured by the surface layer of the hydrophilic second inorganic fine particles, so that the ink is clear and high. The water in the ink is quickly filtered by the hydrophilic second inorganic fine particle layer, penetrates into the receiving layer, and is quickly adsorbed in the gap between the powder coatings. When the hydrophobic resin composition particles have hydrophilic inorganic fine particles on their surfaces, they are absorbed by the water-soluble resin of the hydrophobic resin composition particles.

Preferably, the hydrophobic inorganic fine particles are also sufficiently smaller than the average particle diameter of the hydrophobic resin composition particles so that the surface of the hydrophobic resin composition particles can be sufficiently covered. Considering this point, usually, those having an average particle size of 5 μm or less, preferably 1 nm to 1 μm are preferably used. The hydrophobic inorganic fine particles may be about １ ／ of the average particle diameter of the hydrophobic resin composition particles,
Preferably it is 1/10 or less, particularly preferably 1
/ 100 or less.

Commercial products can also be suitably used for such hydrophobic inorganic fine particles. Examples of such commercially available products include, for example, Aerosil (registered trademark) R972, R972V, and R97, which are anhydrous silicas of Nippon Aerosil Co., Ltd.
2CF, R974, R202, R805, R812S,
Titanium dioxide T805, RX200, RY200, etc.,
Anhydrous silica H15, H2 manufactured by Clariant Japan
0, H30, H2000, H2000 / 4, H300
4, H2015EP, H2050EP and the like.

In the present invention, the substrate is not particularly limited, but usually, paper, synthetic paper, synthetic resin sheet and the like are preferably used. Examples of the synthetic resin sheet include sheets made of polyester, polyvinyl chloride, polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polyamide, and the like. Examples of the synthetic paper include those obtained by extruding a mixture of a polyolefin resin or another synthetic resin as a resin component, a required inorganic filler, and the like.

[0049]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited by these examples.

Example 1 (Preparation of powder coating) 100 parts by weight of a styrene-acrylic copolymer resin (Hymer UNI-3000, manufactured by Sanyo Chemical Industries, Ltd., softening point 98 ° C.) was mixed with a water-soluble resin polyethylene oxide-polypropylene oxide. The mixture was melt-kneaded with 30 parts by weight of a polymer (CP-1000L, manufactured by Sumitomo Seika Co., Ltd.), cooled, pulverized and classified to obtain an average particle size of 11.0 μm
Was prepared. 100 parts by weight of this hydrophobic resin powder composition and 3.9 parts by weight of hydrophilic silica fine particles (200 manufactured by Nippon Aerosil Co., Ltd., average particle size: 12 nm) as hydrophilic inorganic fine particles were mixed and stirred to obtain a powder coating material. Was prepared.

(Preparation of Ink-Jet Recording Paper) The above-mentioned powder coating is sprayed onto the entire surface of a commercially available plain paper using a commercially available electrostatic spraying device, and then adhered thereto. Then, the powder coating was fixed on plain paper, and the powder coating particles were partially fused to each other at the same time to form a 20 μm thick resin layer having voids between the particles as an ink receiving layer.

(Inkjet Recording Characteristics) Using a commercially available inkjet printer (Epson PM-750C), inkjet recording was carried out on the above inkjet recording paper, and the ink absorbency and color development were examined. Immediately after ink-jet recording the color chart prescribed by the Japan Standards Association on the recording paper, the ink absorbability was touched with the fingertip on the image. The time was marked as x. The color development of the ink was measured using a Macbeth densitometer (model number RD-914) at the darkest part. Table 1 shows the results.

Example 2 A powder was prepared in the same manner as in Example 1, except that 30 parts by weight of polyvinyl alcohol (PVA-117, manufactured by Kuraray Co., Ltd.) was used as the water-soluble resin. A coating material was prepared, and using this, an ink jet recording paper was prepared. In the same manner as in Example 1, the ink absorptivity and color development were examined. Table 1 shows the results.

Example 3 A powder coating composition was prepared in the same manner as in Example 1 except that 30 parts by weight of hydroxyethyl cellulose (AH-15 manufactured by Sumitomo Seika Co., Ltd.) was used as the water-soluble resin. Was prepared, and using this, an ink jet recording paper was prepared. In the same manner as in Example 1, the ink absorptivity and color development were examined. Table 1 shows the results.

Comparative Example 1 In place of the hydrophobic resin powder composition comprising the styrene / acrylic copolymer resin and the water-soluble resin polyethylene oxide-polypropylene oxide copolymer in Example 1, only the styrene / acrylic copolymer resin was used. A powder coating was prepared in the same manner as in Example 1 except that a hydrophobic resin powder having an average particle size of 11.0 μm was used, and an ink jet recording paper was prepared using the same. In the same manner as in Example 1, the ink absorptivity and color development were examined. Table 1 shows the results.

[0056]

[Table 1]

[0057]

According to the aqueous ink jet recording sheet of the present invention, while the powder coating has a partial gap therebetween,
In an aqueous inkjet recording sheet having a resin layer fused to each other as an ink receiving layer on a base material, the powder coating material partially exposes the water-soluble resin, while exposing the surface of the water-soluble resin to an average particle content. It is composed of hydrophobic resin composition particles having a diameter of 5 to 20 μm, and hydrophilic second inorganic fine particles having an average particle diameter of 1 nm to 1 μm and covering the surfaces of the hydrophobic resin composition particles.

Accordingly, when the aqueous inkjet ink adheres to such an aqueous inkjet recording sheet, the colorant in the ink is quickly captured by the water-soluble resin and the hydrophilic inorganic fine particles of the ink receiving layer, and
Moisture is not only quickly captured by such a water-soluble resin and hydrophilic inorganic fine particles, but also penetrates and is captured by the voids between the powder coating particles.

Thus, according to the ink jet recording sheet of the present invention, while the ink receiving layer is made of a single layer powder coating made of a hydrophobic resin, the hydrophobic resin particles are made of a water-soluble resin and hydrophilic inorganic fine particles. Thus, while the ink receiving layer is a single layer made of a hydrophobic resin, the ink receiving layer is excellent in ink absorption and coloring.

As described above, in the aqueous ink jet recording sheet according to the present invention, the powder coating material for forming the ink receiving layer mainly has a hydrophobic resin and has excellent ink absorbability by itself. The material is not particularly limited, and in addition to paper having excellent hygroscopicity, it is possible to form a high-performance ink receiving layer on various hydrophobic base materials, for example, base materials made of various synthetic resins and metals. it can.

Further, according to the present invention, by forming a surface layer made of hydrophilic second inorganic fine particles on the resin layer, the colorant in the ink is coated on the surface made of the above hydrophilic second inorganic fine particles. Since it is more quickly captured by the layer, a clear image can be formed at a high density without bleeding.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional perspective view schematically showing one example of a hydrophobic resin composition particle used in the present invention.

FIG. 2 is a schematic view showing a cross section of one embodiment of the ink jet recording sheet according to the present invention.

FIG. 3 is a schematic view showing a cross section of another embodiment of the ink jet recording sheet according to the present invention.

[Explanation of symbols]

11: water-soluble resin particles, 12: hydrophobic resin, 21, 31
... hydrophobic resin composition particles, 22, 32 ... hydrophilic inorganic fine particles, 23, 33 ... powder paint, 24, 34 ... voids, 2
5, 35: base material, 26, 36: resin layer (ink receiving layer), 37: hydrophilic second inorganic fine particles, 38: surface layer.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 201/00 B41J 3/04 101Y F-term (Reference) 2C056 FC06 2H086 BA15 BA16 BA33 BA35 BA36 BA45 4J038 BA032 BA042 CA041 CB051 CC061 CE022 DD001 DF022 HA216 HA286 HA446 KA15 KA20 MA02 MA14 NA06 PA07 PB11 PC10

Claims (9)

[Claims] An aqueous ink jet recording sheet having a resin coating formed on a substrate as an ink receiving layer on a substrate as a powder coating, wherein the powder coating has a partial gap therebetween, and wherein the powder coating is A part of the water-soluble resin is exposed on the surface thereof, and the hydrophobic resin composition particles contained therein and the hydrophilic inorganic fine particles covering the surface of the hydrophobic resin composition particles. An aqueous ink jet recording sheet characterized by the above-mentioned. 2. A powder coating composition according to claim 1, wherein said water-soluble resin particles are partially exposed to the surface thereof and have an average particle diameter of 1 to 30 μm.
The aqueous ink jet recording sheet according to claim 1, comprising m hydrophobic resin composition particles, and hydrophilic inorganic fine particles having an average particle diameter of 1 nm to 1 µm covering the surface of the hydrophobic resin composition particles. 3. The aqueous inkjet recording sheet according to claim 1, wherein the proportion of the water-soluble resin is in the range of 5 to 50% by weight based on the total amount of the hydrophobic resin and the water-soluble resin. 4. The aqueous ink jet recording sheet according to claim 1, wherein the powder coating is obtained by coating 100 parts by weight of hydrophobic resin composition particles with 3 to 12 parts by weight of hydrophilic inorganic fine particles. 5. The method according to claim 1, wherein the hydrophilic inorganic fine particles are silica, alumina,
The aqueous inkjet recording sheet according to any one of claims 1 to 4, wherein the aqueous inkjet recording sheet is titanium oxide or calcium carbonate. 6. The aqueous ink jet recording sheet according to claim 1, further comprising a surface layer formed of hydrophilic second inorganic fine particles on the resin layer. 7. A method of melting and kneading a hydrophobic resin and a water-soluble resin,
After pulverization, a part of the water-soluble resin is exposed on the surface of the hydrophobic resin particles, and the resulting hydrophobic resin composition particles are mixed with hydrophilic inorganic fine particles.
A method for producing a powder coating for an aqueous inkjet recording sheet, comprising: coating the surface of the hydrophobic resin composition particles with the hydrophilic inorganic fine particles. 8. A hydrophobic resin composition particle contained while partially exposing the water-soluble resin to the surface thereof, and hydrophilic inorganic fine particles covering the surface of the hydrophobic resin composition particle. Dry coating of the powder coating consisting of and on the substrate, and heated, while the powder coating partially has a gap between them,
A method for producing an aqueous inkjet recording sheet, comprising forming a resin layer fused to each other as an ink receiving layer on a substrate. 9. Hydrophobic resin composition particles contained while partially exposing the water-soluble resin to the surface thereof, and hydrophilic inorganic fine particles covering the surfaces of the hydrophobic resin composition particles. Dry coating of the powder coating consisting of and on the substrate, and heated, while the powder coating partially has a gap between them,
Forming a resin layer fused together on a base material,
A method for producing an aqueous ink jet recording sheet, comprising forming a surface layer made of hydrophilic second inorganic fine particles on the resin layer.