JPH0521757B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heat-melting transfer type heat-sensitive transfer sheet capable of expressing halftones.

(Prior Art of the Invention and Problems Therewith) In recent years, information technology has progressed with captain systems, text-based multiplex televisions, etc., and it has become possible to print out text images from some televisions.

Conventionally, heat-sensitive coloring and heat-sensitive transfer methods have been considered promising for printing out TV images due to their low noise, maintenance-free, simplicity, compactness, and light weight, but binary recording is the main method. The reproduction of halftones has various problems in terms of resolution, density gradation reproducibility, etc.

Conventionally, methods for reproducing photographic images such as binary recording images and halftones include methods that use sublimation dyes and lamination of multiple layers of thermofusible inks containing pigments and having different melting points. A method of using a multilayer heat-sensitive transfer sheet made of
No. 43881 and Japanese Patent Application No. 1982-205798), but the former has poor storage stability after printing, and the latter has insufficient reproduction of halftones, each of which has drawbacks and has not been put to practical use.

(Problems to be Solved by the Invention) The present invention solves the disadvantages of a multilayer heat-sensitive transfer sheet formed by laminating multiple heat-melt ink layers containing colorants and having different melting points. This solves the problem of insufficient shading and reproduction (the fact that only extreme shading can be expressed).

(Detailed Description of the Invention) The present invention will be described in detail below with reference to the drawings. FIG. 1 shows a multilayer thermal transfer sheet 1 according to the present invention.
2, 3 and 4 are heat-sensitive transfer layers, 5 is a coloring agent, 6 is a heat conduction regulator, and 7 is a support, respectively.

As the support 7, those used as supports for conventional heat-sensitive transfer sheets, such as polyester film, polyimide film, cellophane film, and capacitor paper, can be used.

The multilayer thermal transfer sheet 1 of the present invention has this support 7
Thermal transfer layers 2, 3, and 4 are sequentially laminated thereon.
The transfer layer only needs to be multi-layered, and the transfer layer has three layers as shown in the drawing.
Although the number of layers is not limited, approximately 3 to 5 layers are suitable. Each of the heat-sensitive transfer layers 2, 3, and 4 is a layer containing at least a thermoplastic resin and/or wax, a colorant 5, and a heat conduction regulator 6. Specific examples of the thermoplastic resin include polyester, polyamide, polystyrene, polyethylene-vinyl acetate copolymer, and the like.

In addition, specific waxes include carnauba wax, Montan wax, Candy wax,
Examples include microcrystal wax and paraffin wax.

As the coloring agent 5, carbon black, yellow lead,
Organic pigments such as cadmium yellow, red iron, cobalt purple, ultramarine blue, chrome green, and chromium oxide, as well as organic pigments such as Hansa Yellow G, permanent orange, parallette, fire red, rhodamine lake B, and phthalocyanine blue, as well as disperse dyes and oil-soluble dyes. Examples include dyes such as

On the other hand, the heat conduction regulator 6 specifically includes silica,
It is an inorganic fine powder of precipitated calcium carbonate, magnesium carbonate, calcium hydroxide, calcium silicate, aluminum hydroxide, barium sulfate, titanium oxide, glass, kaolin, etc. that has heat resistance and appropriate thermal conductivity. The particle size is preferably 15μ or less.

Each of the heat-sensitive transfer layers 2, 3, and 4 may be formed by an appropriate coating method using a composition containing at least one of the above-mentioned thermoplastic resin and wax, a colorant 5, and a heat conduction regulator 6. . In forming each layer, as can be understood to some extent from the drawings, the melting point of the thermoplastic resin and/or wax constituting each layer is 5 to 25 degrees Celsius as the layer is farther away from the support 7. The filling amount of the heat conduction modifier 6 is 0.5 to 2.5 parts by weight relative to 100 parts by weight of the ink used for forming the heat-sensitive transfer layer, as the distance from the support 7 increases.
Furthermore, the filling amount of the colorant 5 is set so that the filling amount of the colorant 5 decreases sequentially at intervals of 100 parts by weight of the ink used for forming the heat-sensitive transfer layer as the distance from the support 7 increases. It is necessary to set the values so that they decrease sequentially at intervals of 3 to 7% by weight. The numerical values that define the spacing between these layers are the values necessary to reliably express halftones; below each lower limit, the melting point difference will not be clear, and above the upper limit, the ink will not work properly. This is not preferable because it results in poor coating suitability. With this configuration, the filling rate of the heat conduction modifier is higher toward the support, so that the difference in temperature rise of the heat-sensitive transfer layers 2, 3, and 4 due to the amount of heat applied from the support 7 side is small. As a result, the efficiency of providing a difference in melting point appears more clearly, resulting in a good intermediate tone surface. FIG. 2 is an explanatory diagram showing the state of thermal transfer using the multilayer thermal transfer sheet 1 of the present invention. When a high amount of heat is applied, the thermal transfer layer 2,
When a low amount of heat is applied, only the heat-sensitive transfer layer 4 is transferred, and when an intermediate amount of heat is applied, the heat-sensitive transfer layers 3 and 4 are transferred to the heating head 10. It will be understood that the expression of intermediate tones is performed in accordance with the amount of heat applied.

(Example) Prescribed black ink (melting point 86-96
℃) with a solid gravure plate (20μ depth), then overprint the prescribed black ink (melting point 83℃), and then overprint the prescribed black ink (melting point 70℃) on top of that to create a three-layer A multilayer thermal transfer sheet was created. This is image receiving paper (manufactured by Mitsubishi Paper Industries; TTR-T; Beck 460).
0.25mj in 2msec) and transferred using a thermal transfer recording machine (manufactured by Toshiba; thermal simulator) (0.25mj in 2msec,
Under conditions of 0.35 mj and 0.5 mj/dot), transfer occurred from each layer depending on the amount of heat, and stepwise shading was obtained.

Prescription Thyroid #244 (fine silica powder, manufactured by Fuji Davison Chemical) 5 parts by weight Unbleached Montan Wax 6715 (manufactured by Kato Yoko)
35 parts by weight Sumitate (ethylene vinyl acetate) 5 parts by weight KA-10 (manufactured by Sumitomo Chemical) Toluene 20 parts by weight Methyl ethyl ketone 15 parts by weight Methyl isobutyl ketone 10 parts by weight Carbon Black #1000 (manufactured by Mitsubishi Chemical)
10 parts by weight Prescription Thyroid #244 (fine silica powder) 3 parts by weight Carnauba Wax No. 1 (manufactured by Kato Yoko) 35 parts by weight Sumitate KA-10 (manufactured by Sumitomo Chemical) 5 parts by weight Toluene 22 parts by weight Methyl ethyl ketone 20 parts by weight Methyl isobutyl Ketone 10 parts by weight Carbon Black #1000 5 parts by weight Prescription Rice Wax A (manufactured by Kokura Gosei) 35 parts by weight Sumitate KA-10 5 parts by weight Toluene 24.5 parts by weight Methyl ethyl ketone 19 parts by weight Methyl isobutyl ketone 14 parts by weight Carbon Black #1000 2 parts by weight Thyroid #244 0.5 parts by weight

[Brief explanation of the drawing]

FIG. 1 is a schematic structural explanatory diagram of a multilayer thermal transfer sheet of the present invention, and FIG. 2 is an explanatory diagram showing the state of thermal transfer. 1... Multilayer thermal transfer sheet, 2, 3, 4... Heat sensitive transfer layer, 5... Colorant, 6... Heat conduction regulator.

Claims (1)

[Claims] 1. On a support, a thermoplastic resin and/or wax, a colorant, and a heat-resistant inorganic solid powder (hereinafter referred to as a heat conduction modifier) for increasing the thermal conductivity of the heat-sensitive transfer layer. The melting point of each heat-sensitive transfer layer is 5 to 5 as the layer farther from the support is.
The loading rate of the colorant decreases sequentially at intervals of 25°C, and the filling rate of the colorant is 3 to 7% by weight based on 100 parts by weight of the ink used to form the heat-sensitive transfer layer as the layer is farther away from the support. The filling rate of the heat conduction modifier gradually decreases with time, and the filling rate of the heat conduction modifier decreases as the layer is further away from the support.
1. A multilayer thermal transfer sheet, characterized in that the content is set to decrease sequentially at intervals of 0.5 to 2.5% by weight relative to 100 parts by weight.