JPH04169288A - Thermal transfer recording medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is a method for transferring a heat-sensitive sublimation dye or a heat-melting migration dye to a transfer target using a heat-generating recording member such as a thermal head or a thermal pen. The present invention relates to a thermal transfer recording medium used in a method for recording transferred images.

<Prior art> As a means for printing video images, computer graphic images, etc. using a heat-generating recording member such as a thermal head or a thermal vent, a method containing a heat-sensitive sublimation or heat melt transferable disperse dye or an oil-soluble dye is used. There is a technique in which a heat-sensitive transfer recording medium in which a transfer layer is provided on a base film is used, and this is overlapped and transferred onto a transfer target.

In order to transfer a video image or a computer graphic image with high quality, it is desired that color development with high density can be obtained by the transfer. For this purpose, methods are used in which strong pressure is applied or high printing energy is applied when the thermal transfer recording medium and the transfer target are overlapped and transferred. At this time, if only a transfer layer containing a heat-sensitive sublimation dye or a heat-melt migration dye is provided on the polyester film that is the base material of the heat-sensitive transfer recording medium, the binder resin of the transfer layer will be transferred to the transferred material along with the dye. may transfer to other areas and damage the transferred image. As a solution to this problem, there is a method of providing an adhesive layer between the base film and the transfer layer.

Many studies have been conducted regarding this adhesive layer. However, generally, by providing an adhesive layer, some of the dye is adsorbed to the adhesive layer, resulting in less dye being transferred to the transfer target. Further, the thickness of the adhesive layer causes a decrease in thermal conductivity, which has the disadvantage of lowering the density of the image.

<Problems to be Solved by the Invention> The present invention has been made in view of the above-mentioned drawbacks of the prior art, and aims to provide an adhesive layer that does not impair adhesiveness or cause a decrease in density.

<Means to solve the problem> As a result of various studies to achieve the above objectives,
It has been found that the above-mentioned drawbacks of the prior art can be solved by forming an adhesive layer made of a specific material between the base film and the ink layer. In other words, by selecting a material that can maintain high adhesive strength even when the film thickness is thin, it is possible to provide a high-density and high-quality image, and at the same time, it is possible to improve the adsorption of the material to the adhesive layer without sacrificing thermal efficiency during transfer. can be reduced.

As a result of examining various resins to choose the preferred material for forming such an adhesive layer with strong adhesive strength, the experimental results showed that resins mainly composed of polyurethane resin and vinyl chloride vinyl acetate copolymer resin were the most preferable. I got it.

It was also found that the adhesive force was further strengthened by adding a platinum catalyst to this resin.

That is, the thermal transfer recording medium of the present invention has a polyester film as a base material, on which an ink layer containing a heat-sensitive sublimation dye or a heat-melting transferable dye is formed, and the ink layer is mainly composed of a polyurethane resin and a vinyl chloride-vinyl acetate copolymer resin. It is characterized by being bonded with an adhesive layer.

The mixing ratio of the polyurethane resin and vinyl chloride vinyl acetate copolymer resin is 10 parts by weight of the vinyl chloride vinyl acetate copolymer resin per 100 parts by weight of the polyurethane resin in terms of solid content ratio.

Heat-sensitive sublimation dyes or heat-melting migration dyes include diarylmethane, triarylmethane, thiazole, methine, azomethane, xanthine, acridine, thiazine, azine, acridine, azo,
Spirogipyran, isodorinospiropyran, fluoran, rhodamine ductam, anthraquinone, etc. are used, and these dyes are combined with binders such as polyvinyl butyral resin, vinyl acetal resin, polyester resin, cellulose resin, acrylic resin, polyamide resin, etc. to prepare an ink.

Note that conventional adhesive layers require a weight of 0.5 g/m or more, but the adhesive layer used in the present invention has a weight of 0.5 g/m" or more.
．． It is possible to reduce the amount to 5 g/m" or less, and in particular, it is preferably 0.2 g/m" or less when considering heat response etc., and in order to obtain the effect as an adhesive layer, 0.0 g/m" or less is preferable.
It is preferable to set it to 2 g/m'' or more.

<Example> A polyethylene terephthalate film with a thickness of 4.5 μm is used as the base film. The adhesive layer forming composition described below was applied onto the base film at a dry weight of 0.1 g/m.
A dye ink having the following composition was further applied thereon and dried to obtain a heat-sensitive transfer recording medium.

Adhesive layer forming composition composition dye ink composition Comparative example 1> This is the thermal transfer recording medium of Example with the adhesive layer removed.

<Comparative Example 2> The adhesive layer of the thermal transfer recording medium of Example was changed to an adhesive layer formed from a composition having the formulation shown below.

Adhesive layer forming composition composition Polyester resin (manufactured by Toyobo Co., Ltd., Vylon 600) 8 parts by weight Methyl ethyl ketone: Toluene - 12192 parts by weight <Transfer recording test and results> Thermal transfer recording media of Examples and Comparative Examples 1 and 2 were The ink layer is superimposed facing the dedicated image receptor, and a head applied voltage of 13.5V to 15V is applied from the back side of the thermal transfer recording medium. O
V, pulse width 3ms e c.

~1Bmsec, heated with a thermal rad under the conditions of 6
Four gradations of YELLOW SMAGENTA and CYAN colors were printed.

FIG. 1 shows the reflection density with respect to the gradation frequency of each recording medium.

As can be seen from these results, the reflection density of the curve of Comparative Example 2 is considerably lower than that of Comparative Example 1 without an adhesive layer, but the curve of Example is compared with that of Comparative Example 1 without an adhesive layer. It can be seen that the reflection density did not decrease that much.

<Effects of the Invention> The thermal transfer recording medium of the present invention prevents dyes in the transfer layer from being adsorbed to the adhesive layer and does not cause a decrease in thermal efficiency, so it is possible to suppress a decrease in image density, thereby producing high quality images. This makes it possible to stably form a transferred image.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the difference in reflection density between transferred images using the recording medium of the present invention and a conventional recording medium.

Claims (1)

[Claims] A heat-sensitive transfer recording medium characterized in that an ink layer containing a heat-sensitive sublimation dye or a heat-melt migration dye is adhered to a polyester film with an adhesive layer mainly made of a polyurethane resin and a vinyl chloride-vinyl acetate copolymer resin.