JP2000229474A - Water base ink jet recording sheet, its manufacture and powdery coating material for manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water base ink jet recording sheet of superior water base ink jet ink absorbability forming a sharp and high density image, its manufacturing method and a powdery coating material for the manufacture. SOLUTION: A water base ink jet recording sheet is provided with ink acceptive layer 16 formed of powdery coating materials 13 having spaces 14 partially formed among respective materials and fusion bonded one another formed on a base 15, and the powdery coating material 13 is composed of hydrophobic resin composition particles 11 containing first inorganic fine particles of hydrophilic properties partially exposed on their surfaces and second inorganic fine particles 12 of hydrophilic properties coating the surfaces of the hydrophobic resin composition particles 11. Also water-absorption resin particles can be used in place of the first inorganic fine particles 11 of hydrophilic properties.

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 jet recording sheet having an ink receiving layer formed on a base material and having a mutually interfused ink receiving layer, with a powder coating having partial voids therebetween. In the above, the powder paint is a hydrophilic first paint.
While partially exposing the inorganic fine particles of the above to the surface, the hydrophobic resin composition particles contained therein and the hydrophilic second inorganic fine particles covering the surface of the hydrophobic resin composition particles comprise The aqueous ink jet recording sheet is provided.

According to the present invention, there is provided an aqueous ink jet recording sheet having, on a substrate, an ink-receiving layer formed by fusing mutually with a powder coating having partially voids therebetween. Body paint, some of the water-absorbent resin particles,
There is provided an aqueous inkjet recording sheet comprising hydrophobic resin composition particles contained while being exposed on the surface thereof, and hydrophilic inorganic fine particles covering the surface of the hydrophobic resin composition particles.

Further, according to the present invention, the hydrophobic resin and the hydrophilic first inorganic fine particles are melt-kneaded and pulverized, and a part of the hydrophilic first inorganic fine particles is mixed with the hydrophobic resin. After being exposed to the surface of the particles, the contained hydrophobic resin composition particles are mixed with hydrophilic second inorganic fine particles, and the surface of the hydrophobic resin composition particles is exposed to the hydrophilic resin particles. There is provided a method for producing a powder coating material for an aqueous inkjet recording sheet, comprising coating with a second inorganic fine particle.

According to the present invention, the hydrophobic resin and the water-absorbent resin particles are melt-kneaded and pulverized to partially expose the water-absorbent resin particles to the surface of the hydrophobic resin particles. After forming the hydrophobic resin composition particles contained therein, this is mixed with hydrophilic inorganic fine particles, and the surface of the hydrophobic resin composition particles is coated with the hydrophilic inorganic fine particles. A method for producing a powder coating is provided.

[0010] In addition to the above, according to the present invention, the hydrophobic first inorganic fine particles are partially exposed to the surface thereof, and the hydrophobic first resin fine particles are contained therein. A powder coating consisting of hydrophilic second inorganic fine particles covering the surface of the material particles is dry-coated on a substrate, and heated, so that the powder coating has partial voids therebetween. While doing
There is provided a method for producing an aqueous ink jet recording sheet, comprising forming an ink receiving layer fused together on a substrate.

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-absorbent resin particles to the surface thereof. An ink obtained by dry-coating a powder coating composed of hydrophilic inorganic fine particles on a base material and heating the powder coating to partially fuse the powder coating with each other while having a partial gap therebetween. There is provided a method for producing an aqueous inkjet recording sheet comprising forming a receiving layer on a substrate.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, preferred embodiments of the first aqueous ink jet recording sheet according to the present invention will be described. The first water-based inkjet recording sheet is a water-based inkjet recording sheet having, on a substrate, an ink-receiving layer formed by fusing mutually with a powder coating having partially voids therebetween. The paint has an average particle size of 1
A part of the hydrophilic first inorganic fine particles of 5 μm to 5 μm is exposed on the surface, and the average particle diameter of the first inorganic fine particles is 5 to 20 μm.
The hydrophobic resin composition particles of μm and hydrophilic second inorganic fine particles of 1 nm to 1 μm in average particle diameter covering the surface of the hydrophobic resin composition particles.

A description will now be given of a powder coating used for producing such a first aqueous ink jet recording sheet. This powder coating is prepared by melt-kneading a hydrophobic resin and hydrophilic first inorganic fine particles having an average particle size of 1 μm to 5 μm, and pulverizing the mixture so as to have an average particle size of 5 to 20 μm. A part of the inorganic fine particles of 1 is exposed to the surface of the hydrophobic resin particles to form the contained hydrophobic resin composition particles, which are then made of hydrophilic second inorganic fine particles having an average particle diameter of 1 nm to 1 μm. And coating the surface of the hydrophobic resin composition particles with the hydrophilic second inorganic fine particles.

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 a (meth) acrylic acid ester. Specifically, examples of the (meth) acrylic acid ester include 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 commercially available 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, the hydrophilic first inorganic fine particles are particles having an average particle size in the range of 1 μm to 5 μm, and commercially available products can be suitably used. Examples of such commercially available products include silica such as Carplex manufactured by Shionogi & Co., Ltd., Mizukasil manufactured by Mizusawa Chemical Industry Co., Ltd., and Fine Seal X-37, 40, 70, 80 manufactured by Tokuyama Corporation. ED-I, ED- manufactured by Yonesho Lime Industry Co., Ltd.
III, ED-V, calcium carbonate such as Callite KT manufactured by Shiraishi Calcium Co., Ltd., and the like.

According to the present invention, such a hydrophilic first
5-30% by weight of the inorganic fine particles based on the hydrophobic resin
These are melt-kneaded, cooled, and then pulverized to have an average particle size of 5 to 20 μm, whereby a part of the hydrophilic first inorganic fine particles is converted to hydrophobic resin particles. The hydrophobic resin composition particles dispersed and contained in the hydrophobic resin particles while being exposed on the surface of the resin can be obtained.

According to the present invention, the hydrophobic resin and the hydrophilic first inorganic fine particles having an average particle diameter in the range of 1 μm to 5 μm are melt-kneaded, cooled, and then cooled to an average particle diameter of 5 to 2 μm.
When crushed to have a particle size of 0 μm, the hydrophilic first
Since the inorganic fine particles of the above have a large average particle size, the kneaded material is cracked mainly at the interface between the hydrophobic resin and the inorganic fine particles, and the inorganic fine particles having such a large particle size are formed on the surface of the hydrophobic resin particles. Part, exposed hydrophobic resin composition particles can be obtained. When the average particle diameter of the hydrophilic first inorganic fine particles is smaller than 1 μm, the kneaded material is uniformly dispersed and contained in the hydrophobic resin particles, and the kneaded material is hardly cracked at the interface. On the other hand, when the average particle diameter of the hydrophilic first inorganic fine particles is larger than 5 μm, the inorganic fine particles are present as independent particles together with the hydrophobic resin composition particles. When dry coating is performed on a base material and heated for fixing, there is a concern that good fixing may be impaired.

As described above, according to the present invention, the hydrophobic resin and the first hydrophilic inorganic fine particles having an average particle size of 1 μm to 5 μm are melt-kneaded, cooled, and pulverized so as to have an average particle size of 5 to 20 μm. By dispersing the inorganic fine particles in hydrophobic resin particles, by containing, the inorganic fine particles,
Some are exposed on the surface of the hydrophobic resin particles, and thus,
By imparting hydrophilicity to the hydrophobic resin particles, it is possible to impart ink absorption and color development to the ink receiving layer formed therefrom.

According to the present invention, an appropriate amount and colorant or an anti-offset agent may be added to the hydrophobic resin composition particles.

The above-mentioned coloring agent 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. Coloring agent, in the resulting hydrophobic resin composition,
Usually, it is used in the range of 1 to 50% by weight, preferably 5 to 40% by weight.

As will be described later, the anti-offset agent is prepared by dry-coating a powder coating on a base material, and then heating and partially melting the coating material to form a gap therebetween. It is blended with a hydrophobic resin, if necessary, so as not to cause offset when forming the fused ink receiving layer.
The offset preventing agent usually has a melting point of 50 to 150.
Various waxes in the range of ° C are preferably used. Specifically, for example, paraffin wax, polyolefin wax such as polyethylene and polypropylene,
Examples thereof include fatty acid metal salts, fatty acid esters, higher fatty acids, and higher alcohols. Such an anti-offset agent is usually used in the obtained hydrophobic resin composition,
It is used in the range of 0.1 to 20% by weight, preferably 0.5 to 10% by weight.

The powder coating used for producing the first aqueous ink jet recording sheet contains the hydrophobic resin and the hydrophilic first inorganic fine particles having an average particle size of 1 μm to 5 μm as described above. Melt and knead at a temperature of about ℃
After cooling, the mixture is pulverized to have an average particle size of 5 to 20 μm to obtain hydrophobic resin composition particles, and then mixed with hydrophilic second inorganic fine particles having an average particle size of 1 nm to 1 μm. It can be obtained by coating the surface of the hydrophobic resin composition particles with the hydrophilic second inorganic fine particles.

The average particle diameter of the hydrophilic second inorganic fine particles is 1
When it is larger than μm, even if such inorganic fine particles are mixed with the hydrophobic resin composition particles and the surface of the hydrophobic resin composition particles is coated, the hydrophobic resin composition particles can be uniformly coated. It is difficult to increase the proportion of the surface not covered with the hydrophilic second inorganic fine particles. As a result, the hydrophobic resin composition particles do not have sufficient hydrophilicity. It is difficult to form an ink receiving layer having excellent ink absorbency and color development.

Such hydrophilic second inorganic fine particles include:
Commercial products can be easily obtained. Specific examples of commercially available products include, for example, Aerosil (registered trademark) 50, 90G, 13 which is anhydrous silica manufactured by Nippon Aerosil Co., Ltd.
0, 200, 200V, 200CF, 200FAD, 3
00, 300CF, 380, OX50, TT600, M
OX80, MOX170, COK84, etc., aluminum oxide C, titanium dioxide P25, etc., anhydrous silica S13, V15, N20, T30 manufactured by Clariant Japan,
T40 and the like can be mentioned.

According to the present invention, such a hydrophilic second
The 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. That is, the hydrophobic resin composition particles 10
The second inorganic fine particles having a hydrophilic content of 3 to 12 relative to 0 parts by weight.
Parts by weight to coat the surface of the hydrophobic resin composition particles, using this as a powder coating, dry-coating on a substrate, heating, and partially melting the powder coating. By having the powder paint partially void in between,
By fusing them together, a resin layer having voids between them is formed as an ink receiving layer on the substrate. 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 an ink receiving 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, as described above, while partially exposing the hydrophilic first inorganic fine particles to the surface, dispersion,
To form a hydrophobic resin composition particle, and a powder coating obtained by coating the surface of the hydrophobic resin composition particle with hydrophilic second inorganic fine particles forms an ink receiving layer. The surface of the ink receiving layer also has the hydrophilic first property.
And second inorganic fine particles.

Therefore, when the amount of the hydrophilic second inorganic fine particles is less than 3 parts by weight with respect to 100 parts by weight of the hydrophobic resin composition particles, the surface of the hydrophobic resin composition particles becomes hydrophilic. And the surface of the ink receiving layer is also not sufficiently coated with the hydrophilic inorganic fine particles, so that the obtained ink jet recording sheet has insufficient color developability, clear and high-density images. Cannot be formed. On the other hand, when the hydrophilic second inorganic fine particles are more than 12 parts by weight based on 100 parts by weight of the hydrophobic resin composition particles, particularly, the hydrophobic resin composition particles are less likely to directly contact the base material, Even if such a powder coating is heated, it is difficult to sufficiently fix it to the substrate.

According to the present invention, a layer composed of hydrophilic third inorganic fine particles can be provided on such an ink receiving layer. As the hydrophilic third inorganic fine particles, usually, the same as the hydrophilic second inorganic fine particles are used, but the type does not need to be the same as the hydrophilic second inorganic fine particles. . Therefore, the hydrophilic third inorganic fine particles may have an average particle diameter in the range of 1 nm to 1 μm, but preferably have an average particle diameter of 1 nm to 50 nm.
And most preferably, the average particle size is 5 to 30 n.
m.

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 powder coating as described above. A coating layer is formed, and then the hydrophilic third inorganic fine particles are dry-coated on the powder coating layer and heated under pressure to form a layer composed of the hydrophilic third inorganic fine particles. The ink receiving layer is fixed on the powder coating layer, thus forming an ink receiving layer which is fused to each other on the base material while the powder coating has a partial gap therebetween. It can be obtained by forming a layer composed of the hydrophilic third inorganic fine particles on the layer.

However, according to the present invention, if necessary,
The powder coating is dry-coated on a substrate to form a powder coating layer, and then the third inorganic fine particles having a hydrophilic property are dry-coated on the powder coating layer to form a hydrophilic coating. A layer composed of the third inorganic fine particles is formed, and then the powder coating layer having a layer composed of the hydrophilic third inorganic fine particles thereon is heated under pressure, and thus, the above-mentioned base material is formed on the base material. The powder coating forms an ink receiving layer which is fused to each other while partially leaving a gap therebetween, and a layer made of the hydrophilic third inorganic fine particles is formed on the ink receiving layer. It can also be obtained by forming.

The third hydrophilic inorganic fine particles have an average particle size of 1
When larger than μm, when inkjet recording is performed on a recording sheet having such a layer of inorganic fine particles on the surface, an obtained image may lack accuracy, and an inkjet recording sheet that gives a high quality image may be obtained. I can't get it. On the other hand, the hydrophilic third 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.

As described above, in the ink jet recording sheet having the layer composed of the hydrophilic third 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 Since it is captured by the layer of the third inorganic fine particles, a clear and high-density image is formed. On the other hand, the water in the ink is quickly filtered by the layer of the hydrophilic third inorganic fine particles to form a receiving layer. It penetrates into it and is quickly adsorbed by the voids between the powder coatings, and is also adsorbed by the hydrophilic inorganic fine particles on its surface.

According to the present invention, the layer composed of the hydrophilic third inorganic fine particles is usually in the range of 10 nm to 10 μm, particularly preferably in the range of 20 nm to 5 μm.

According to the present invention, when a layer composed of hydrophilic third inorganic fine particles is formed on the receiving layer, the powder coating for forming the receiving layer comprises the above-mentioned average particle size. The surface of 100 parts by weight of the hydrophobic resin composition particles having a diameter of 5 to 20 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 5 to 20 μm, the second hydrophilic inorganic fine particles and the hydrophobic inorganic fine particles 3 to 12 parts by weight of the mixture, preferably 5 to 1
It may be coated with 0 parts by weight.

According to such an ink jet recording sheet, when the ink jet ink adheres to the sheet, the colorant in the ink is captured by the layer of the hydrophilic third inorganic fine particles, so that the clear and high density On the other hand, the water in the ink is quickly filtered by the layer of the hydrophilic third inorganic fine particles, 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 adsorbed to the particles.

The hydrophobic inorganic fine particles are also desirably 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.

Commercially available 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, etc. 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 other synthetic resin as a resin component, a required inorganic filler, and the like.

FIG. 1 schematically shows a cross section of an embodiment of the ink jet recording sheet according to the present invention. Each of the hydrophobic resin composition particles 11 is dispersed and contained while partially exposing hydrophilic first inorganic fine particles (not shown) on the surface thereof, and further, the surface thereof is hydrophilic. Are coated with the second inorganic fine particles 12 to form a powder coating material 13,
These powder coatings are mutually fused and fixed on the base material 15 to form the ink receiving layer 16 while partially having the voids 14 therebetween.

FIG. 2 schematically shows a cross section of another embodiment of the ink jet recording sheet according to the present invention. As in the example shown in FIG. 1, each of the hydrophobic resin composition particles 21 partially has hydrophilic first inorganic fine particles (not shown) on its surface.
While dispersing and containing, the surface thereof is further covered with hydrophilic second inorganic fine particles 22;
The powder coatings 23 are formed, and these powder coatings are mutually fused and fixed on the base material 25 while partially forming the voids 24 therebetween, thereby forming the ink receiving layer 26. ing. In this embodiment, a layer 28 made of third inorganic fine particles 27 having a hydrophilic property is further formed on the ink receiving layer 26, and the ink receiving layer has a two-layer structure.

Next, a preferred embodiment of the second aqueous ink jet recording sheet according to the present invention will be described. The second aqueous inkjet recording sheet is a water-based inkjet recording sheet having, on a substrate, an ink receiving layer formed by fusing with each other while a powder coating has a partial gap therebetween. The coating contains a portion of the water-absorbent resin particles having an average particle size of 1 μm to 20 μm, while exposing the surface to the surface thereof, and containing the hydrophobic resin composition particles having an average particle size of 5 to 20 μm; It is composed of hydrophilic inorganic fine particles having an average particle diameter of 1 nm to 1 μm which coat the surface of the particles.

Thus, a powder coating used for producing such a second aqueous ink jet recording sheet will be described. This powder coating is obtained by melt-kneading a hydrophobic resin and water-absorbent resin particles having an average particle size of 1 μm to 20 μm,
２０20 μm, while partially exposing the water-absorbent resin particles to the surface of the hydrophobic resin particles,
After making the hydrophobic resin composition particles contained, this is mixed with hydrophilic inorganic fine particles having an average particle diameter of 1 nm to 1 μm,
It can be obtained by coating the surface of the hydrophobic resin composition particles with the hydrophilic inorganic fine particles.

That is, the powder coating used for producing the second aqueous inkjet recording sheet is the same as the first hydrophilic inorganic fine particles used for producing the powder coating for the first aqueous inkjet recording sheet described above. Instead, the only difference is that a water absorbent resin is used. Therefore, here, the hydrophobic resin composition particles used in the production of the powder coating for the second aqueous inkjet recording sheet will be described.

The above-mentioned water-absorbing resin is not particularly limited in a polymer material constituting the water-absorbing resin, but is preferably a chemically cross-linked water-absorbing resin, and the water absorption of deionized water per unit weight of the resin. Amount is 100-100
Those in the range of 0 g / g are preferable, and particularly, 300 to
Those in the range of 1000 g / g are preferred. Examples of such a water-absorbing resin include a crosslinked product of polyacrylic acid partial sodium salt (for example, Aqualic (registered trademark) CA manufactured by Nippon Shokubai Co., Ltd., Sun Fresh ST-500MPS manufactured by Sanyo Chemical Industry Co., Ltd.), and the like. , Starch / acrylic acid graft polymer partial sodium salt (for example, Sanfresh ST-500S or 100 manufactured by Sanyo Chemical Industries, Ltd.)
Can be mentioned.

In addition, a crosslinked isobutylene-sodium maleate copolymer, a crosslinked styrene-sodium maleate copolymer, a starch-sodium polyacrylate grafted product, a saponified starch-polyacrylonitrile grafted product, cellulose-polystyrene Examples thereof include a grafted product of sodium acrylate and a vinyl alcohol-sodium (meth) acrylate copolymer. Commercially available products can be obtained for such a chemically crosslinked type water absorbent resin.

According to the present invention, the water-absorbent resin has a softening point of 70 to 100 ° C. so that it can be effectively dispersed in the hydrophobic resin when melt-kneaded with the hydrophobic resin particles.
Is preferably within the range. Similarly, when the hydrophobic resin is melt-kneaded with the water-absorbent resin particles, the softening point is in the range of 70 to 120 ° C. so that the water-absorbent resin is well dispersed in the obtained hydrophobic resin particles. Is preferred. As such a hydrophobic resin, the same one as described above is suitably used.

According to the present invention, the average particle size is from 1 μm to 2 μm.
5 μm to 30% by weight of water-absorbent resin particles having a mean particle size of 5 μm to 2 μm are mixed with a hydrophobic resin and cooled.
By pulverizing so as to have a particle diameter of 0 μm, the hydrophobic resin composition particles dispersed and contained in the hydrophobic resin particles while partially exposing the water-absorbent resin particles to the surface of the hydrophobic resin particles can be obtained. it can.

Generally, the above-mentioned chemically crosslinked water-absorbent resin does not melt by heating, and therefore has an average particle size of 20%.
If it exceeds μm, it is difficult to uniformly disperse the hydrophobic resin in the hydrophobic resin even if the resin is melted, kneaded with the resin, and pulverized. However, in the present invention, when the water-absorbent resin and the hydrophobic resin are melt-kneaded and pulverized, not all of the water-absorbent resin used need be dispersed in the hydrophobic resin, and a part is obtained. It may be present as particles independent of the hydrophobic resin composition particles.

According to the present invention, as described above, the hydrophobic resin and the water-absorbent resin particles having an average particle diameter in the range of 1 μm to 20 μm are melt-kneaded, and after cooling, have an average particle diameter of 5 to 20 μm. When pulverizing, since the water-absorbent resin particles have a large average particle size, the kneaded material mainly cracks at the interface between the hydrophobic resin and the water-absorbent resin particles, and the water-absorbent resin particles having such a large particle size are reduced. And hydrophobic resin composition particles exposed on the surface of the hydrophobic resin particles.
When the average particle size of the water-absorbent resin particles is smaller than 1 μm, the water-absorbent resin particles are uniformly dispersed in the kneaded material, and the kneaded material is less likely to crack at the interface. On the other hand, when the average particle diameter of the water-absorbent resin particles is larger than 20 μm, the water-absorbent resin particles are melt-kneaded with the hydrophobic resin, cooled, and cooled to an average particle diameter of 5 μm.
It is difficult to obtain hydrophobic resin particles in which some of the water-absorbent resin particles are exposed to the surface of the hydrophobic resin particles even if the water-absorbent resin particles are crushed to have a particle size of about 20 μm. Exists as

As described above, according to the present invention, the hydrophobic resin and the water-absorbent resin particles having an average particle diameter of 1 μm to 20 μm are melt-kneaded, cooled, and pulverized to have an average particle diameter of 5 to 20 μm. The water-absorbent resin particles are dispersed and contained in the hydrophobic resin particles by the hydrophobic resin particles,
Some are exposed on the surface of the hydrophobic resin particles, and thus,
By imparting hydrophilicity to the hydrophobic resin particles, it is possible to impart ink absorption and color development to the ink receiving layer formed therefrom.

According to the present invention, such a hydrophobic resin composition particle may be blended with an appropriate amount of a coloring agent or an anti-offset agent as described above.

The powder coating used for the production of the second aqueous ink jet recording sheet contains the hydrophobic resin and the water-absorbent resin particles having an average particle size of 1 μm to 20 μm as described above.
After being melt-kneaded at a temperature of about 100 to 200 ° C. and cooled, the mixture is pulverized so as to have an average particle size of 5 to 20 μm, thereby partially exposing the water-absorbent resin particles to the surface of the hydrophobic resin particles. And preparing hydrophobic resin composition particles dispersed in hydrophobic resin particles, and mixing the same with the hydrophilic second inorganic fine particles having an average particle diameter of 1 nm to 1 μm in the same manner as described above. By coating the surface of the hydrophobic resin composition particles with the hydrophilic second inorganic fine particles, a powder coating used for producing a second aqueous inkjet recording sheet can be obtained.

As described above, the hydrophilic second 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, 3 to 12 parts by weight of hydrophilic second inorganic fine particles are mixed with 100 parts by weight of the hydrophobic resin composition particles to coat the surface of the hydrophobic resin, and this is used as a powder coating. , Dry coating on the substrate, heating,
By partially melting the powder coating, the powder coating is partially fused with each other while having a gap therebetween, and a resin layer having a gap between each other is used as an ink receiving layer. Form on top. The voids between the powder coatings are usually in the range of 1 nm to 200 nm. Also,
In the present invention, such a thickness of the ink receiving layer,
Usually, it is in the range of 2 to 80 μm, preferably 5 to 80 μm.
The range is 50 μm.

According to the present invention, the water-absorbing resin particles are partially exposed on the surface, and the hydrophobic resin composition particles having the surface coated with hydrophilic inorganic fine particles form the ink receiving layer. As a result, the surface of the receiving layer is also covered with water-absorbent resin particles and hydrophilic inorganic fine particles.

Accordingly, 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 with the hydrophilic inorganic fine particles. In addition, the surface of the ink receiving layer is not sufficiently covered with the hydrophilic inorganic fine particles, so that the obtained ink jet recording sheet has insufficient coloring properties and cannot form a clear and high-density image.
On the other hand, when the hydrophilic inorganic fine particles are the hydrophobic resin composition particles 100
When the amount is more than 12 parts by weight with respect to parts by weight, particularly, the hydrophobic resin composition particles are hardly in direct contact with the substrate, and even when such a powder coating is heated, it is sufficiently fixed to the substrate. It is difficult to let.

According to the present invention, the powder coating is dry-coated on the substrate and heated to form the above-described ink-receiving layer on the substrate. Similarly, a layer composed of hydrophilic third inorganic fine particles can be provided thereon.

[0061]

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 material) 80 parts by weight of styrene / acrylic copolymer resin (Hymer UNI-3000, manufactured by Sanyo Chemical Industries, Ltd., softening point 98 ° C) was used as the first hydrophilic inorganic fine particles. The mixture was melt-kneaded together with 20 parts by weight of hydrophilic silica fine particles (“Mizukasil P-527, average particle size 1.6 μm” manufactured by Mizusawa Chemical Industry Co., Ltd.), cooled, pulverized and classified to obtain an average particle size of 1.1.
A 0 μm hydrophobic resin powder composition was prepared. 100 parts by weight of the hydrophobic resin powder composition and 5 parts by weight of hydrophilic silica fine particles (200 manufactured by Nippon Aerosil Co., Ltd., average particle size: 12 nm) as the second hydrophilic inorganic fine particles were mixed and stirred.
A powder coating 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 In Example 1, hydrophilic calcium carbonate fine particles (“E” manufactured by Yonesho Lime Industry Co., Ltd.) were used as the first hydrophilic inorganic fine particles.
DV ", average particle size 5.0 [mu] m), except that 20 parts by weight of a powder coating material was prepared, 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.

COMPARATIVE EXAMPLE 1 In Example 1, styrene-acrylic copolymer resin 90 was used.
Parts by weight and as the first hydrophilic inorganic fine particles, hydrophilic silica fine particles (Nippon Aerosil Co., Ltd. 5
A powder coating was prepared in the same manner as in Example 1, except that 10 parts by weight (0, average primary particle diameter 30 nm) was used, and an ink jet recording paper was prepared using the powder coating. In the same manner as in Example 1, the ink absorptivity and color development were examined. Table 1 shows the results.

Example 3 93 parts by weight of a styrene / acrylic copolymer resin (Hymer UNI-3000, manufactured by Sanyo Chemical Industries, Ltd., softening point: 98 ° C.) were mixed with 93 parts by weight of a water-absorbing resin (polyacrylic acid partial sodium salt crosslinked product, average particle size). (6.0 μm) was melt-kneaded together with 7 parts by weight, cooled, pulverized and classified to prepare a hydrophobic resin powder composition having an average particle size of 11.0 μm. 100 parts by weight of the hydrophobic resin powder composition and 5 parts by weight of hydrophilic silica fine particles (200 manufactured by Nippon Aerosil Co., Ltd., average primary particle diameter: 12 nm) were mixed and stirred to prepare a powder coating. 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 1 (Preparation of Powder Coating) 80 parts by weight of styrene-acrylic copolymer resin (Hymer UNI-3000, manufactured by Sanyo Chemical Industries, Ltd., softening point 98 ° C.) was used as first hydrophilic inorganic fine particles. The mixture was melt-kneaded together with 20 parts by weight of hydrophilic silica fine particles (“Mizukasil P-527, average particle size 1.6 μm” manufactured by Mizusawa Chemical Industry Co., Ltd.), cooled, pulverized and classified to obtain an average particle size of 1.1.
A 0 μm hydrophobic resin powder composition was prepared. 100 parts by weight of the hydrophobic resin powder composition and 5 parts by weight of hydrophilic silica fine particles (200 manufactured by Nippon Aerosil Co., Ltd., average particle size: 12 nm) as the second hydrophilic inorganic fine particles were mixed and stirred.
A powder coating 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.

Next, hydrophilic silica fine particles (380, manufactured by Nippon Aerosil Co., Ltd., average primary particle diameter: 7 nm) are sprayed on the ink receiving layer by using an electrostatic spraying device, and are adhered. The ink was heated to about 80 to 100 ° C. to fix a layer having a thickness of 3 μm made of the above-mentioned hydrophilic silica fine particles on the ink receiving layer, thereby preparing an ink jet recording paper.

(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 specified by the Japan Standards Association on the recording paper, the ink absorbability was touched with the fingertip on the image, and when the ink did not adhere to the fingertip, it was evaluated as ○, and the ink partially adhered to the fingertip The time was indicated by x. The color development of the ink was measured using a Macbeth densitometer (Model No. RD-914) at the darkest portion. Table 1 shows the results.

[0072]

[Table 1]

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The first aqueous ink jet recording sheet according to the present invention is an aqueous ink jet recording sheet having an ink receiving layer formed on a base material and having an ink receiving layer fused to each other, with a powder coating having a gap therebetween. In the recording sheet, the powder coating material contains a hydrophobic first inorganic fine particle having an average particle diameter of 1 μm to 5 μm while partially exposing it to the surface thereof, and contains a hydrophobic resin having an average particle diameter of 5 to 20 μm. The composition comprises composition particles 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.

Therefore, if the aqueous ink jet ink adheres to such an aqueous ink jet recording sheet, the colorant in the ink becomes the first and second ink receiving layers.
Is quickly captured by the hydrophilic inorganic fine particles, and moisture is not only rapidly captured by such 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 doubled by hydrophilic inorganic fine particles. The ink receiving layer is excellent in ink absorbency and coloring even though the ink receiving layer is a single layer made of a hydrophobic resin.

The second water-based ink jet recording sheet according to the present invention is a water-based ink-jet recording sheet having an ink receiving layer formed on a base material and having a powder coating partially fused with each other and having a mutually fused ink receiving layer. In the above, the powder coating, while partially exposing the water-absorbent resin particles having an average particle size of 1 μm to 20 μm, on the surface thereof, containing hydrophobic resin composition particles having an average particle size of 5 to 20 μm, It is composed of hydrophilic inorganic fine particles having an average particle size of 1 nm to 1 μm which cover the surfaces of the hydrophobic resin composition particles.

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

Thus, according to the aqueous ink jet recording sheet of the present invention, while the ink receiving layer is composed of a single layer powder coating mainly composed of a hydrophobic resin, the hydrophobic resin particles are made of a hydrophilic resin and a hydrophilic resin. The hydrophilicity is imparted doubly by the inorganic fine particles, and therefore, the ink receiving layer is excellent in ink absorbency and color developability even though it is a single layer mainly composed of a hydrophobic resin.

As described above, in the water-based 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, by forming a layer comprising hydrophilic inorganic fine particles on the ink receiving layer according to the present invention, the colorant in the ink is more quickly captured by the layer comprising hydrophilic inorganic fine particles. A clear image can be formed at a high density without bleeding.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a cross section of one embodiment of an ink jet recording sheet according to the present invention.

FIG. 2 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, 21 ... hydrophobic resin composition particles, 12, 22 ... second
Hydrophilic inorganic fine particles, 13, 23 ... powder paint, 14, 2
4 ... voids, 15, 25 ... base material, 16, 26 ... ink receiving layer, 27 ... hydrophilic third inorganic fine particles, 28 ... hydrophilic third inorganic fine particles.

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2C056 EA04 FC06 2H086 BA13 BA15 BA32 BA34 BA35 BA36 BA41 BA45 4J038 CA041 CB051 CC041 CC061 CF031 CG141 CJ031 DD041 HA216 HA286 HA446 KA02 KA20 LA06 LA07 MA03 MA04 NA12 MA06

Claims (14)

[Claims] An aqueous ink jet recording sheet having an ink-receiving layer on a base material, wherein the ink-receiving layer is mutually fused while the powder coating has a partial gap therebetween. The first inorganic fine particles are partially exposed to the surface thereof, and the hydrophobic resin composition particles contained therein and the hydrophilic second inorganic particles covering the surfaces of the hydrophobic resin composition particles An aqueous ink jet recording sheet comprising fine particles. 2. A hydrophobic resin having an average particle size of 5 to 20 μm, wherein the powder coating contains a part of the hydrophilic first inorganic fine particles having an average particle size of 1 μm to 5 μm and exposes them on the surface. 2. The aqueous ink jet recording sheet according to claim 1, comprising composition particles and hydrophilic second inorganic fine particles having an average particle diameter of 1 nm to 1 [mu] m covering the surfaces of the hydrophobic resin composition particles. 3. The aqueous ink jet 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 second inorganic fine particles. Recording sheet. 4. The aqueous inkjet recording sheet according to claim 1, wherein the hydrophilic first or second inorganic fine particles are silica, alumina, titanium oxide or calcium carbonate. 5. The aqueous ink jet recording sheet according to claim 1, wherein a layer comprising hydrophilic third inorganic fine particles is formed on the ink receiving layer. 6. An aqueous ink jet recording sheet having an ink receiving layer formed on a base material and having mutually fused ink receiving layers, wherein the powder coating has a water absorbing property. It is characterized by being composed of hydrophobic resin composition particles contained therein and hydrophilic inorganic fine particles covering the surface of the hydrophobic resin composition particles while partially exposing the resin particles to the surface thereof. Aqueous ink jet recording sheet. 7. The powder coating material has an average particle size of 1 μm to 20 μm.
A part of the water-absorbing resin particles is exposed to the surface, and the hydrophobic resin composition particles having an average particle diameter of 5 to 20 μm are contained, and the average covering the surface of the hydrophobic resin composition particles The aqueous ink jet recording sheet according to claim 6, comprising hydrophilic inorganic fine particles having a particle size of 1 nm to 1 µm. 8. The aqueous ink jet recording sheet according to claim 6, 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. 9. The aqueous ink jet recording sheet according to claim 6, wherein the hydrophilic inorganic fine particles are silica, alumina, titanium oxide or calcium carbonate. 10. The water-absorbent resin has a water absorption of deionized water in the range of 100 to 1000 g / g, and 70 to 100 g / g.
C. in the range of 70 to 120.degree.
The aqueous inkjet recording sheet according to claim 5, having a softening point in the range of: 11. A method of melting and kneading a hydrophobic resin and hydrophilic first inorganic fine particles and pulverizing them to expose a part of the hydrophilic first inorganic fine particles on the surface of the hydrophobic resin particles. Meanwhile, after making the hydrophobic resin composition particles contained therein, this 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 paint for an aqueous ink jet recording sheet, which comprises coating. 12. A hydrophobic resin and an average particle diameter of 1 μm to 5 μm.
Is melt-kneaded with the first hydrophilic fine inorganic particles, and pulverized so as to have an average particle size of 5 to 20 μm, and a part of the first hydrophilic fine particles is formed on the surface of the hydrophobic resin particles. After the exposed hydrophobic resin composition particles were exposed, the particles were mixed with hydrophilic second inorganic fine particles having an average particle diameter of 1 nm to 1 μm, and the surface of the hydrophobic resin composition particles was treated as described above. 2. A coating with hydrophilic second inorganic fine particles.
2. The method for producing a powder coating material for an aqueous inkjet recording sheet according to item 1. 13. The hydrophobic resin composition particles contained and the surface of the hydrophobic resin composition particles are partially exposed to the surface of the hydrophilic first inorganic fine particles. A powder coating composed of hydrophilic second inorganic fine particles is dry-coated on a substrate and heated, so that the powder coating is fused to each other while partially having a gap therebetween. A method for producing an aqueous inkjet recording sheet, comprising forming an ink receiving layer on a substrate. 14. Hydrophobic resin composition particles having an average particle size of 5 to 20 μm while partially exposing hydrophilic first inorganic fine particles having an average particle size of 1 μm to 5 μm to the surface thereof; A powder coating composed of hydrophilic second inorganic fine particles having an average particle diameter of 1 nm to 1 μm and covering the surface of the hydrophobic resin composition particles is dry-coated on a substrate, and heated to form the powder. 14. The method for producing an aqueous ink jet recording sheet according to claim 13, wherein an ink receiving layer formed by fusing with each other is formed on the base material while the powder coating has a partial gap therebetween.