JP2684559B2 - Thermal transfer receiving paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal transfer image receiving paper useful for making full-color copying of electronic images such as video, television and color graphics.

[Conventional technology and its problems]

The image receiving paper for thermal transfer printing is required to have appropriate cushioning properties and flatness so that the thermal head and its contact can be made soft and uniform during printing.

Therefore, various methods have been proposed in the past, but each method has drawbacks as described below, and a satisfactory method has not been obtained yet. That is, (1) a method in which a resin layer having a rubber-like shape is provided between the surface layer of the base material and the dyeing layer. When the dyeing layer is provided on the surface layer of the base material, it is difficult to obtain a resin having good adhesion to the surface layer. In addition, when a material having good adhesiveness is printed by using, for example, a sublimable dye, the dye continues to diffuse in a moist heat environment and an image is blurred.

(2) Method of dispersing inorganic filler in polymer and strongly stretching during melt film formation to provide voids between polymer and filler To provide effective voids, it is necessary to use a coarse filler. When using, the roughness affects the image and fine print dots cannot be reproduced.

(3) Method of obtaining a porous layer at the time of coating by using a polymer blend or a special coagulation method Since this is a special production method, the productivity is low and the cost is high.

(4) Method of applying a coating liquid containing a porous organic or inorganic filler In many cases, the roughness of the filler appears on the surface and the image is rough, and if the amount of the filler is reduced, sufficient cushioning properties can be obtained. However, the contact between the image receiving paper and the thermal head is poor, and the image is still rough.

There are problems such as.

[Means for solving the problem]

The inventor of the present invention does not have the above-mentioned problems of the prior art and has a proper cushioning property and flatness, and can make contact with the thermal head softly and uniformly. As a result of earnest research for the purpose of providing a thermal transfer image-receiving paper capable of copying an electronic image such as a full-color image with high quality, the results are as follows: 1 The outer diameter is 2 μm in an aqueous dispersion of a resin that is not resistant to organic solvents The following layer is formed by coating and drying a liquid in which a hollow spherical plastic pigment of a water dispersion system is dispersed, and an image receiving layer is laminated and formed on the intermediate layer. 2 An organic solvent is formed on a substrate. It is possible to form a layer obtained by coating and drying a liquid obtained by dispersing a hollow spherical plastic pigment of an aqueous dispersion having an outer diameter of 2 μm or less in an aqueous dispersion of a resin having no resistance to an image receiving layer. Become known the door, it was completed the present invention.

The resin which is not resistant to the organic solvent mentioned here is a resin which is not resistant to toluene, benzene, xylene, methyl ethyl ketone and the like.

An example of the resin having no resistance to the organic solvent in the present invention is an aqueous polyester resin.

In the present invention, the use of a resin that is not resistant to an organic solvent means that when an aqueous resin is used for the image receiving layer, it is not necessary to use an organic solvent resistant resin for the layer in contact with the image receiving layer in the first invention. This is because.

 Next, the present invention will be described in detail.

(1) Base material The base material used in the present invention includes plain paper, coated paper, plastic film, synthetic paper and the like.

(2) Hollow Spherical Plastic Pigment As the hollow spherical plastic pigment, a powder-like substance can be used by dispersing it in a solvent-based coating liquid, but in this case, swelling due to the solvent may occur, so that an aqueous dispersion system is used. It is preferable to use one of the following. The water-dispersion type is preferably, for example, an acrylic-styrene copolymer resin type, and the particle type is 2 μm or less in outer diameter, preferably 1 μm.
Finer than m is preferable in order to maintain the flatness and gloss of the image receiving paper.

As a hollow plastic pigment, there are inorganic ones, but this one is generally fragile and not only does not show sufficient cushioning property due to breakage of spheres at the time of preparing a coating solution, coating or printing. On the contrary, the fragments become small projections and hinder the flatness, which is not preferable.

(3) Binder of coating liquid As the binder of the coating liquid, various binder resins can be used. In the first invention, the adhesiveness with the base material, the affinity with the resin used in the image receiving layer, and the like are used. It is desirable to take into consideration the selection, and in the case of the second invention, it is desirable to take into consideration the adhesiveness with the base material.

Particularly in the case of the sublimation type thermal transfer image receiving paper, a saturated copolymer resin is usually used for the image receiving layer.
It is preferable to use the same type of resin for the intermediate layer in terms of adhesion to the image receiving layer, image quality, and particularly sharpness of dot reproduction. The reason why the dots are sharply reproduced is not clear, but the resin with good affinity for the dye is thin in the surface layer and distributed in the vertical direction of the paper in the middle layer, so it is wider than the one that is thickly distributed in the surface layer. It is thought that this is because the boundary of the spread in the direction becomes clear.

Further, the mixing ratio of the resin and the pigment is practically used in a wide range, but when the mixed layer directly becomes the image receiving layer, the ratio of the resin is relatively increased from the viewpoint of affinity with the dye or the ink resin, In the case of the intermediate layer, relative to the weight of the resin,
The weight of the pigment can be used in an equivalent amount to about 8 times.

Further, in order to improve the coatability, other components such as a thickener and a small amount of a wetting agent, a defoaming agent and a filler may be added to the coating liquid. The use of the above additives can improve the function of the coating layer.

Generally, an aqueous dispersion of a saturated copolyester resin is relatively expensive, and when other inorganic fillers are mixed, there is a drawback that the stability of the system is likely to collapse, but the plastic spherical hollow pigment used in the present invention is Since it can be optionally added without impairing the stability of the system, there is an advantage that an effect as an inexpensive bulking agent and an opacifying agent can be expected.

As a coating method of the coating liquid, various methods such as known reverse roll coating and air knife coating can be adopted, and various methods such as normal hot air drying and infrared drying can be used for drying after coating.

〔Example〕

 Example-1 Next, examples of the present invention will be described.

A 100 μm-thick polypropylene film coated with 1 μm of chlorinated polypropylene was coated with a coating liquid-1 having the following composition using a reverse roll and dried with a hot air dryer. The coating thickness after drying was 20 μm.

Composition of coating liquid-1 Aqueous polyester resin (Vylonal MD 1200 Toyobo Co., Ltd.) 30 parts Hollow spherical plastic pigment liquid (Lowpaque OP-3
4J Rohm and Haas Co., Ltd.) 60 parts Isopropyl alcohol 10 parts This product has a coating thickness of 3 μm after drying with a liquid of the following composition
Was coated and dried.

Composition of coating liquid-2 Aqueous polyester resin (Vylonal MD 1200, Toyobo) 90 parts Release agent (SF 8421 Toray Silicone) 5 parts The obtained image receiving paper was printed using a printer (Hitachi VY50). The color density and dot reproducibility were good.

Example-2 Chlorinated polypropylene having a thickness of 1 μm was coated on cast-coated paper having a continuous amount of 110 kg. A coating liquid having the following composition was applied to this product using a reverse roll and dried with a hot air dryer to obtain an image receiving paper.

 The coating thickness after drying was 20 μm.

Composition of coating liquid Water-based polyester resin (Vylonal MD 1200, Toyobo) 30 parts Hollow plastic pigment liquid (Ropaque OP-62, manufactured by Rohm and Haas) 10 parts Release agent Amino-modified silicone (KF 3935, Shin-Etsu Silicone) 0.5 parts Above When the image receiving paper of No. 2 was printed using a printer (VY50 manufactured by Hitachi, Ltd.), a good image was obtained with a slightly low color density but no missing dots peculiar to the paper base.

Claims (5)

(57) [Claims] 1. An intermediate layer comprising a base material, which is obtained by coating and drying a liquid obtained by dispersing a hollow spherical plastic pigment of an aqueous dispersion having an outer diameter of 2 μm or less in an aqueous dispersion of a resin having no resistance to an organic solvent. And a heat-transfer image-receiving paper characterized by being formed by laminating an image-receiving layer on the intermediate layer. 2. The thermal transfer image receiving paper according to claim 1, wherein the image receiving layer is formed of an aqueous resin. 3. The thermal transfer image receiving paper according to claim 2, wherein the aqueous resin of the image receiving layer is an aqueous polyester resin. 4. An image receiving layer comprising a base material, which is obtained by coating and drying a liquid obtained by dispersing a hollow spherical plastic pigment of an aqueous dispersion having an outer diameter of 2 μm or less in an aqueous dispersion of a resin having no resistance to an organic solvent. A thermal transfer image-receiving paper characterized by being laminated as. 5. The thermal transfer image-receiving paper according to claim 1, wherein the resin having no resistance to an organic solvent is an aqueous polyester resin.