JPS6321631B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ink sheet, and more particularly to an ink sheet that has improved printability and repeatability by providing an adhesive layer between a base material and an ink layer.

BACKGROUND OF THE INVENTION Conventionally, copying devices such as printers and facsimile machines have used ink sheets consisting of ink layers consisting of dyes, pigments, binders, low melting point agents, plasticizers, etc., and base materials such as plastics, metal foils, and paper. In such an ink sheet, it has been proposed to provide an adhesive layer as an intermediate layer between the ink layer and the base material in order to improve the adhesion between them. An ink sheet provided with such an adhesive layer has improved adhesion with the ink layer, but
There was a drawback that distortion occurred at the interface between the ink layer and the adhesive layer due to evaporation of the solvent in the ink, resulting in fine cracks in the ink layer. If no adhesive layer is provided between the ink layer and the base material, the problem of cracking does not occur, but the adhesion between the base material and the ink layer is completely insufficient, making repeated use impossible. .

Therefore, it has been desired to develop an ink sheet that can be used repeatedly without causing cracks as described above. The present invention is intended to meet such demands, and includes an ink sheet having a base material and an ink layer, in which an adhesive layer containing fine powder is provided between the base material and the ink layer. Features.

That is, the present invention alleviates strain at the interface between the ink layer and the intermediate layer by providing an adhesive layer containing fine powder as an intermediate layer in the ink sheet, and also improves the adhesion between the ink layer and the base material. It is intended to increase one's strength. In the present invention, it is particularly preferable that the fine powder added to the adhesive layer is the same type of fine powder as the fine powder in the ink layer. The reason for this is that the fine powder contained at the interface between the adhesive layer and the ink layer has the same physical and chemical properties, so they are easily compatible with each other, and as a result, the adhesion between both layers is improved. by.

The same type of fine powder means metal oxides such as zinc oxide and aluminum oxide, metal powders, and inorganic powders such as carbon black.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

The ink sheet S of the present invention includes a base material 1, an adhesive layer 2, and an ink layer 3.

The ink material constituting the ink layer can be obtained, for example, as follows. Dye (#151, manufactured by Nippon Kayaku)
It is obtained by kneading 1 g of polyethylene glycol (#4000, manufactured by NOF Corporation), and 4 g of carbon black (manufactured by Tokai Carbon Co., Ltd.) in 20 cc. of toluene in a ball mill for 8 hours. The obtained ink material is abbreviated as ink material A.

As the resin constituting the adhesive layer, a hot melt type resin such as polyvinyl acetate resin, acrylic resin, polyamide resin, etc. is used. The material for the adhesive layer is, for example, 1.6 g of polyamide resin (#1300 manufactured by Henkel) and 2 g of carbon black (manufactured by Tokai Carbon) mixed with 28 g of toluene.
It is obtained by kneading it with cc in a ball mill for 6 hours. The obtained adhesive material is abbreviated as adhesive material B.

As mentioned above, the powder blended into the hot melt resin is preferably the same type as the powder in the ink layer, but different types can also be used. The blending ratio of hot melt type resin and additive powder in the adhesive layer is about 0.6 to about 1.9 to 1 part resin. If the blending ratio is less than about 0.6, cracks will occur in the ink layer, and if it is greater than about 1.9, the adhesive force of the adhesive will be reduced.

The ink sheet S is manufactured, for example, as follows. Capacitor paper (16μm) as base material
The adhesive material B described above was coated on a 10×10 cm surface to a thickness of 10 μm using a bar coater, and dried with air to form an adhesive layer 2. Next, the above-described ink material A is applied onto the adhesive layer 2 to a thickness of 30 μm using a bar coater, and left to dry to form the ink layer 3.

The appearance of the obtained ink sheet S was smooth;
As is clear from the micrograph in Figure 2 (40x magnification), no abnormalities were observed. In FIG. 2, a large number of dark white small piece structures K are ink fine particle structures, and crack-like areas L are areas where the solvent in the ink has evaporated. A recording paper 4 such as plain paper was placed on top of the ink sheet S, and copies were made 10 times using a thermal printer.
As a result, the ink layer remained usable without peeling off.

For comparison, an ink sheet was produced that was exactly the same as described above, except that the adhesive (polyamide resin) layer did not contain particles. As is clear from the micrograph in Figure 3 (magnification: 40x), cracks can be seen on the surface of the ink sheet. In the photograph, the black part M is the part where the ink layer has separated into islands, and the white part N
is a part of the adhesive layer where the lower layer is exposed due to the separation, and the linear white part O indicates a crack. As described above, the above-mentioned ink sheet having an adhesive layer containing no particles as an intermediate layer can only be copied five times at the most.

As explained above, since the ink sheet of the present invention has a structure in which an adhesive layer containing fine powder is provided between the base material and the ink layer, the difference in shrinkage rate between the adhesive layer and the ink layer can be reduced. As a result, the generation of cracks in the ink layer can be prevented and a homogeneous ink layer can be obtained, and as a result, the adhesion between both layers is improved, which has the effect of enabling repeated use. It also has the effect of increasing the mechanical strength of the base material.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a state in which recording paper is superimposed on the ink sheet of the present invention, FIG. 2 is a micrograph showing the fine particle structure of ink in the ink layer of the ink sheet of the present invention, and FIG. , is a micrograph showing the fine particle structure of ink in the ink layer of a conventional ink sheet. 1... Base material, 2... Adhesive layer, 3... Ink layer,
S...Ink sheet.

Claims (1)

[Scope of Claims] 1. An ink sheet having a base material and an ink layer, characterized in that an adhesive layer containing fine powder is provided between the base material and the ink layer. 2. The ink sheet according to claim 1, wherein the adhesive layer is made of an adhesive and a fine powder of the same type as the fine powder in the ink layer. 3. The ink sheet according to claim 1 or 2, wherein the fine powder is carbon black.