JPS5939595A - Heat transfer recording material for gradational image - Google Patents

Abstract

PURPOSE:To provide a heat transfer recording material which enables the recording of a gradational image on a plain paper with one ink layer by providing more than one kind of heat transfer ink layers varied in the amount of coloring agents per unit area on the same base material in belts. CONSTITUTION:More than one kinds of heat transfer ink layers 2a, 2b, 2c... varied in the amount coloring agents per unit area are arranged on the same base material in belts employing thermal transfer inks comprising coloring agents (e.g. a black dye and an oil black), waxes (e.g. paraphine wax), resins (e.g. ethylene polymer) and oils (e.g. oleic acid to obtain a desired heat transfer recording material 3. Preferable for the base material are a proper 10-15mum thick and film of polyimide, polycarbonate, teflon, polyester and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel thermal transfer recording material for gradation images. More specifically, the present invention relates to a thermal transfer recording material capable of recording gradation images on plain paper.

In recent years, thermal printers, thermal facsimiles, and the like have used thermal transfer materials formed by applying thermal transfer ink onto a base material to obtain robust images on plain paper. However, since the entire amount of ink is generally transferred, it is not possible to record grayscale images such as photographs. Therefore, using a thermal transfer recording material coated with two layers of black ink with a high melting point and ink layer with a low melting point, we transfer and record the black ink onto plain paper using a low-energy heat pulse and the gray ink using a high-energy heat pulse. A method is proposed. However, with this method, it is difficult to uniformly smear the two layers, and it is also difficult to see the applied energy.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a thermal transfer recording material that uses a single layer of ink and is capable of recording gradation images on plain paper.

In the present invention, the above object is achieved by providing two or more types of thermal transfer ink layers having different amounts of colorants per unit area in the form of bands on a substrate. Here, "band-shaped" means that two or more types of thermal transfer ink layers with different amounts of colorant per unit area may be divided into strips in the width direction of the base material, or two or more types of thermal transfer ink layers with different amounts of coloring agent per unit area may be provided in the width direction of the base material, or in the same manner in the length direction of the base material. It may be provided.

Thermal transfer ink layers with different amounts of colorant per unit area are
Obtained by changing the amount of the same ink applied or by changing the content ratio of the colorant in the thermal transfer ink layer (in this case, the amount of ink applied may be the same or may be changed) be able to.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the thermal transfer recording material for gradation images of the present invention. In this figure, 1 is the base material, 2a, 2
b, 2e, . . . are thermal transfer ink layers having different amounts of colorants per unit area, and 3 is a thermal transfer material for gradation images of the present invention. Here 2a, 2b, 2c,
2d, 2a -.-* are thermal transfer ink layers exhibiting different optical reflection densities when the entire amount of ink is transferred to plain paper.

The thermal transfer recording method using the thermal transfer recording material 3 for gradation images of the present invention is as follows in the case of facsimile. That is, a document with shading, such as a photograph, is quantized in terms of density during transmission, and on the receiving side, transfer printing is performed on plain paper using a layer of thermal transfer ink that matches the density level. FIG. 2 shows how an image of one density level is printed. Before printing the next density level, the plain paper is noed and the plain paper is fed to the next density level so that it overlaps the thermal transfer ink layer. Plain paper may be cut paper or rolled paper. The number of gradations can be increased as required by increasing the types of thermal transfer ink layers.

The base material (1) used in the present invention preferably has a thickness of 8 to 20 .mu.m, particularly 10 to 15 .mu.m, from the viewpoint of transfer sensitivity and physical strength.

The material should be selected from those with excellent heat resistance and strength. Paper such as capacitor paper and resin films such as polyimide, polycarbonate, Teflon, and polyester are preferably used.

The thermal transfer ink layer used in the present invention is composed of colorants, waxes, resins, oils, and the like.

Examples of colorants include black dyes and pigments such as oil black and carbon black. Dyes and pigments of other colors can also be used.

Examples of waxes include parafille wax, carnauba wax, montan wax, low molecular weight polyethylene wax, hollow wax, beeswax, and rice wax.

Examples of resins include ethylene copolymers, tetradine derivatives, petroleum resins, and styrene resins.

Examples of oils include oleic acid and petrolatum.

Example: A carbon ink with a carbon black percentage of 12% and 896.3% was applied to a 10μ capacitor paper at 3 to 51/d.
A heat transfer paper for gradation was obtained by smearing. 5- When each was thermally transferred onto plain paper and the optical reflection density was measured, they were 1.7±0, 1.1, 2±0.1.
It became 0.7±0.1.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the thermal transfer recording material for gradation images of the present invention. In the figure, 1 is the base material, 2a% 2bb 2cb 2ds 2
1"--1 is a thermal transfer ink layer having a different amount of coloring agent per unit area, and 3 is a thermal transfer material for gradation images of the present invention. Figure 2 shows an image of one density level printed. In the figure, 4 is plain paper, 5 is a thermal head, and 6 is a platen roll.

Claims (3)

[Claims] (1) A thermal transfer recording material for gradation images, characterized in that two or more types of thermal transfer ink layers containing different amounts of colorants per unit area are provided in a band shape on the same substrate. (2) The thermal transfer recording material for gradation images according to claim 1, wherein the thermal transfer ink layers have different amounts of colorants per unit area, and the applied amount of the same ink is varied. (3) The thermal transfer recording material for gradation images according to claim 1, wherein the thermal transfer ink layers having different amounts of colorants per unit area are composed of inks having different content ratios of colorants.