JPS5996993A - Color sheet for thermal transfer - Google Patents

Abstract

PURPOSE:To provide a color sheet for thermal transfer better in the environmental resistance and the color reproducibility of images by providing a colorant layer containing a mixture of a basic sublimating dye and a dispersing sublimating dye and a binder on a support. CONSTITUTION:A thermal transfer color sheet is arranged to have a colorant layer containing a mixture of a basic sublimating dye (e.g. dyes of the formulas I , II and III) and a dispersing sublimating dye (e.g. dyes of formulas IV, V and VI) and a binder (e.g. polysulfone and polycarbonate) on a support (e.g. condenser paper and thin sheet paper). The use of the basic dye alone may cause a change in the color tone during the prolonged preservation of images while the use of the dispersing dye alone provides a drawback of varying in the resolution and color tone of images during the prolonged preservation. The mixed use of the basic sublimating dye and the dispersing sublimating dye produces a transfer color sheet better in the environmental resistance and color reproducibility of images.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color sheet for thermal transfer used in a color hard copy using a thermal transfer recording method.

Conventional configuration and its problems A compact method for converting electrical signals from television images and character images from computer terminals into hard copies.

A thermal transfer color recording method is a recording method that is inexpensive and easy to maintain and inspect. This method uses a thermal transfer color sheet (hereinafter abbreviated as color sheet) in which a heat transferable coloring material is applied to a base material such as paper, and this coloring material is applied by a thermal head controlled by an image signal. This method involves thermal transfer dyeing on recording paper (hereinafter abbreviated as image-receiving paper). Full-color notebooks can be obtained by using colorants of yellow, cyan, agenta, and black. The dye as a colorant is transferred onto the receiver paper by a transfer process of melting, vaporization or sublimation. especially,
Sublimable basic dye 9 disperse dye is good in terms of gradation reproducibility and color tone. As the image-receiving paper, clay paper is generally used for basic dyes, and polyester coated paper is used for disperse dyes. However, if only a basic dye is used, a competitive reaction occurs between the color spots on the image receiving paper, which may cause a change in tone during long-term storage of the image. Further, when only disperse dyes are used, the dyes diffused into the image receiving paper are not preserved in certain cases during long-term storage, but move, resulting in changes in image resolution and color tone.

OBJECTS OF THE INVENTION An object of the present invention is to provide a color sheet for thermal transfer that has good environmental resistance and two-color reproducibility of images.

Structure of the Invention The present invention is a color sheet for thermal transfer, in which a coloring material layer containing a mixture of a basic sublimation dye and a dispersible sublimation dye and a binder is provided on a support.

The support here includes capacitor paper, electrolytic capacitor paper, glassine paper, cellulose paper such as tissue paper, other polyimide films that do not cause thermal adhesion under the heating conditions of the thermal head, polycarbonate films with silicone coatings, polysulfone, and polyester. Examples include films. Examples of the binder include polyester resin (for example, polyethylene phthalate), polycarbonate, aminated nylon, polysulfone, glulan, cyanoethyl pullulan, nitrocellulose, and the like.

Typical examples of dyes are shown below. However, the basic sublimable dye is not limited to colored dyes, but may be colorless or light-colored in normal state, but may be colored by electron acceptors.

Basic dye cyan type (71111) 2 (/F6.2) Magenta type (〆4) Yellow type (A5) Dispersible dye cyan type 11 o NHCH3 Magenta yellow type (boiled 12) In the following examples, the above compounds Quote with j6 in parentheses.

FIG. 1 shows a representative example of the structure of the color sheet and the principle of the image forming method of the present invention. In the figure, 1 is a thermal head, and 2 is a color sheet, which is composed of a support 21 and a color material layer 22 consisting of a basic dye, a disperse dye, and a binder. 3 is an image receiving paper having an electron acceptor on its surface, like clay paper. The heat supplied from the thermal head 1 passes through the support 21 and sublimates the dye in the color material layer 22, and an image is formed on the image receiving paper 3 that captures the dye.

A color sheet was prepared by applying a color material layer having the following composition (weight ratio) of dye and binder as a support.

Example cyan color sheet; (dye type 1 + flat 7): polycarbonate = 2:1 Magenta color sheet; (dye/f63 ten flat 9): borisulfone = 1.5:
1 Yellow color sheet; (dye type 5 +/F6.11) : polysulfone = 1
:1 The mixing ratio of the two types of dyes in each color sheet is 1=1 in terms of weight ratio.

Comparative Example 1 Cyan color sheet; dye jθ1: polycarbonate-2:1 magenta color sheet; dye form 3: polysulfone = 1.6:1 yellow color sheet; dye engraving 5: polysulfone-1:1 Comparative Example 2 Cyan color sheet; Dye j67: Polycarbonate = 2:1 Magenta color sheet; Dye form 9: Polysulfone = 1.6:1 Yellow color sheet; Dye form 11: Polysulfone - 1:1 Example and Comparative Example 1 Using a color sheet, an image was formed on clay paper with a thermal head under certain recording conditions. The image was stored in an atmosphere with a temperature of 40° C. and a relative humidity of 90%, and the chromaticity was measured after 5000 hours. The results are shown in Figure 2.

Product a of the present invention did not change from the initial value even after the test, but product b of Comparative Example 1 showed a change.

Next, an image formed on clay paper using the color sheet of Example and an image formed on polyester coated paper using the color sheet of Comparative Example 2 were stored in an atmosphere at 60°C, and after 5000 hours, the border of the image was was measured using a microdensitometer.

The results are shown in FIG. Inventive product a, the change in the boundary line was equivalent to the initial value, but in Comparative Example 2, product C, the boundary line became unclear.

Effects of the Invention The present invention can improve the environmental resistance and resolution stability of images by using a color sheet provided with a coloring material layer containing a mixture of a basic dye and a dispersible dye.

[Brief explanation of drawings]

Figure 1 is a diagram showing the configuration of color sorting and the principle of the image forming method. Figure 2 is a diagram showing changes in image chromaticity in an environmental resistance test. Figure 3 is a diagram showing changes in image resolution in an environmental resistance test. It is. 1...Thermal head, 2...Color sort,
21...Support, 22...Coloring material layer, 3...
...Receiving paper. Name of agent: Patent attorney Toshio Nakao (1st person)
Figure 2 Figure 3 ε-distance ()tyn no+

Claims (1)

[Claims] A color sheet for thermal transfer is provided with a coloring material layer containing a mixture of a basic sublimable dye and a dispersible sublimable dye and a binder on a support.