JPS60135289A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To provide a thermal transfer recording medium having high transfer sensitivity and capable of printing with low energy, by a construction wherein a coloring agent in a coloring material layer is a dye, and a heat-fusible substance is a wax capable of dissolving the dye. CONSTITUTION:The thermal transfer recording medium comprises at least one coloring material layer on a base, which layer comprises at least one coloring agent and a heat-fusible substance. The coloring agent is a dye, e.g., one selected from direct dyes, acid dyes, basic dyes, dispersed dyes, oil-soluble dyes and the like. A wax capable of dissolving the dye used in the coloring material layer is selected as the heat-fusible substance. Accordingly, the covering power of the coloring material layer can be enhanced, the thickness of the layer required for obtaining a required density can be made to be relatively small, and since the sensitivity is high, it is also possible to record (print) at high speed.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a thermal transfer recording medium, and more specifically, the present invention relates to a thermal transfer recording medium that has high transfer sensitivity, can be printed with low energy, and has tamper resistance on a recording sheet such as plain paper. The present invention relates to a thermal transfer recording medium from which a dye transfer image with high resolution can be obtained.

[Prior Art] Thermal paper used as a recording medium cannot prevent printed (recorded) images from being tampered with, and has the drawback of poor preservation of printed (recorded) images because they easily develop color when exposed to heat or organic solvents. On the other hand, a type of thermal transfer recording medium using a heat-melting substance is known as a recording medium with excellent tampering resistance and storage stability. This heat-sensitive transfer recording medium has at least one coloring material layer on a support, and known examples of the coloring material layer include a layer containing a coloring agent and a heat-fusible substance. Pigments such as carbon black are used as the coloring agent. In addition, in order to obtain good visibility of the dye transfer image obtained from the color material layer coated on the support, heat-resistant polymer films with excellent surface smoothness and dimensional stability are used. is used.

When using a thermal printer or thermal facsimile with a thermal head to record a dye transfer image on plain paper or the like using such a thermal transfer recording medium,
Although it is desired to print with low energy, conventional thermal transfer recording media have been insufficient due to low transfer sensitivity. Another drawback is that when designed to have high transfer sensitivity, the result is a dye transfer image with poor resolution. In other words, if a thermal transfer recording medium is designed to have a relatively low transfer sensitivity, it is possible to obtain a clear dye transfer image, but if it is designed to have a high transfer sensitivity, the fixability and resolution of the dye transfer image may be affected. A problem will arise.

As one method for increasing transfer sensitivity, a technique for increasing the thermal conductivity of a coloring material layer is disclosed in Japanese Patent Application Laid-Open No. 75894/1983. This invention is a technology for containing a powdered thermally conductive substance in a coloring material layer, and although it certainly achieves high sensitivity, since the use of additives is stipulated in Article 1, it may vary depending on the type of additives. The purpose of the present invention is to provide a thermal transfer recording medium that has high transfer sensitivity and can be printed with low energy. be.

Another object of the present invention is to provide a heat-sensitive transfer recording medium that has good fixability on a recording sheet such as plain paper and is capable of producing a high-resolution dye transfer image.

Other objects of the invention will become apparent from the following description of the specification.

[Summary of the Invention] As a result of intensive research, the present inventor has discovered that a heat-sensitive transfer recording medium having a coloring material layer containing a coloring agent and a heat-melting substance on a heat-resistant polymer film support, the coloring material layer It has been found that the above object can be achieved when the coloring agent is a dye and the heat-melting substance is a wax capable of dissolving the dye.

This led to the present invention.

That is, in order to achieve the above object, the present inventor used a combination of a dye and a specific wax instead of the conventional method of adding a thermally conductive substance.
It is now possible to increase the covering power of the coloring material layer and make the coloring material layer relatively thin in order to obtain the necessary density.
As a result, the object of the present invention has been successfully achieved.

[Structure of the invention] The present invention will be explained in more detail below.

The thermal transfer recording medium of the present invention has at least one
It has at least one colorant layer containing a seed colorant and a heat-fusible substance.

The coloring agent to be contained in the coloring material layer of the present invention is a dye, and may be selected from, for example, direct dyes, acid dyes, basic dyes, disperse dyes, oil-soluble dyes, etc. 6 Basic dyes preferably used in the present invention Dyes include crystal violet CG, 1.42555 malachite green (
C,1,42000), methyl violet l-(C,1
, 42535), Victoria Blue (C, 1,440
45), triphenylmethane dyes such as Mazienta (c, ■, 42510), auramine (C:, 1.65
diphenylmethane dyes such as 5), astraphloxin FF (C, I.

48070), Eisencathilone Yellow 3GLH (Hodogaya Chemical Co., Ltd. product, [,1,48055), Eisencathilone Red BB)l (C,1,48020) Astrazon Golden Yellow GL (Bayer Co., Ltd. product,
Monothine and azamethine dyes such as C, 1,48054), xatene dyes such as Rhodamine B (C, 1,451?0) and Rhodamine 8G (C, 1,451f10), Astrazone Blue GL (C, 1, 1t.

52), Astrazone Red F3BL (C, 1,110
55) and other thiazole azo and triazole azo dyes, Eisenryoku Chiron Blue-50) I (C, 1, 11
085), quinoneimine dyes such as methylene blue (C0■, 52015), Eisen Chironre, Do GTL
H (C, 1, 11085), Cevron Yellow 3RL (
DuPont product, C, 1, 1108? ), astrazone blue FGL (C, 1, 81512) and other insulating azo dyes and anthraquinone dyes having an onium group at the structural end.

In the present invention, it is also preferable to use oil-soluble dyes (5) In particular, oil-soluble dyes containing metal ions (e.g., Eisenspiron Black GMH Special, manufactured by Futani Kagaku Co., Ltd.)
is preferred. Other known dyes such as acid dyes, basic dyes, disperse dyes, and oil-soluble dyes may be used.

The dyes of the present invention can be used alone or in combination of two or more, and for example, basic dyes and other dyes may be used in combination.

The heat-melting substance to be contained in the coloring material layer of the present invention includes the dye to be contained in the coloring material layer dissolved (5% by weight at 150°C).
Above, preferably 10% by weight or more can be dissolved. ) is selected.

Specific examples of the wax used in the present invention include: 0) Ester wax (natural ester wax such as carnauba wax and Monkun wax, Hoech manufactured by Hoechst)
st WaxE, F, KP, KPS, BJ, OP, OM
.

X22. synthetic ester waxes such as U and 0).

<2) Oxidized wax (wax obtained by oxidizing wax such as paraffin wax and microcrystalline wax, L) NPS-9210, NPS- manufactured by Kiseiro Co., Ltd.
6115, Toyo Pe] PETR0NABA manufactured by Rolight Co., Ltd.
-C, CARDrs 3x4, etc.), ■Amide wax (Stearylamide, 1st/Ilami 1ha, Kao Amide C manufactured by Kao Atlas, etc.), +4) Acid wax (
(Hoechst Wax S, LP, etc.) manufactured by Hoechst.

The wax in the present invention is preferably an amide wax when the dye is, for example, the above-mentioned 11-base dye or oil-soluble dye (particularly one containing metal ions).

It is preferable that the color material layer of the present invention contains a resin. The resin used in the present invention preferably has a softening point (measured by the ring and ball method) of 40 to 200°C, and either a wood-philic polymer or a hydrophobic polymer can be used. Examples of wood-philic polymers include gelatin, gelatin derivatives, cellulose derivatives, proteins such as casein, natural products and natural product derivatives such as polysaccharides such as starch, water-soluble nylon, polyvinyl alcohol, polyvinylpyrrolidone, and acrylamide polymers. Examples include synthetic water-soluble polymers such as water-soluble polyvinyl compounds, and vinyl-based and polyurethane-based polymer latexes. Examples of hydrophobic polymers include U.S. Patent Nos. 3,142,588, 3,143,386, and 3,082.674;
Examples include the synthetic polymers described in 3,220,844, 3,287,289, and 3,411,811. Preferred polyamides include polyvinyl butyral, polyvinyl formal, polyethylene, polypropylene, polyamide, ethyl cellulose,
Cellulose derivatives such as cellulose acetate, polystyrene, polyvinyl butyrate, polyvinyl chloride, polyvinylidene chloride, ethylene-vinyl acetate, hinyl chloride-vinyl acetate copolymer, 1'AX-hinyl-acetic acid butyvinyl-malein resistant terpolymer, polymethyl methacrylate Examples include acrylic resins such as polyisobutylene, rosin derivatives such as ester gum, petroleum resins, coumaron indene resins, cyclic rubbers, and chlorinated combs. In the present invention, one kind or a combination of two or more kinds of these resins are used.

Although the composition ratio of the coloring material layer of the present invention is not limited, the wax is 40 to 90 parts, the dye is 2 to 20 parts, and the resin is 0-30
Department.

As long as the colorant layer of the present invention contains 40 to 90 parts of the wax of the present invention, it does not contain 0 to 20% of wax that has substantially no solubility for dyes (for example, paraffin wax, microcrystalline wax, etc.). But that's fine. Also,
Pigments may be used in combination as long as the effects of the present invention are not impaired.

The color material layer of the present invention may contain various additives in addition to the above components. For example, as a softener, castor oil,
Vegetable oils such as linseed oil, olive oil, animal oils such as whale oil and mineral oils may suitably be used.

The support used as a base material for the heat-sensitive transfer recording medium of the present invention is a polymer film having heat-resistant strength. As for the heat resistance strength, it is necessary to have the strength to maintain the toughness as a support without becoming softened or plasticized by the heating temperature of a heat source such as a thermal head, and to have stability in the SJ method. In addition, it is preferable that the surface is smooth, and it is desired that the coloring material layer containing a heat-fusible substance on the support (2) has sufficient smoothness to exhibit a good transfer rate.

The smoothness was measured using a Beck tester (JISP).
8119) for 100 seconds or more, and 300 seconds
If it is ec or higher, images with better transfer rate and reproducibility can be obtained. Examples of materials include polyethylene,
Resin films such as polyethylene terephthalate, polystyrene, polypropylene, and polyimide are all suitably used. The thickness of the support is preferably about 80 gm or less, particularly 2 to 20 gm, in order to obtain good thermal conductivity. In the thermal transfer recording medium of the present invention, the structure of the back side of the support is arbitrary.

Techniques suitable for applying the colorant layer to a support such as a polymeric film in the heat-sensitive transfer recording medium of the present invention are known in the art, and these techniques can also be used in the present invention. . For example, the coloring material layer is a layer formed by hot-melt coating the composition. As a method for applying the color material layer of the present invention, any known technique such as a reverse roll coater method, an extrusion coater method, a gravure coke method, and a wire coating 1+i method can be employed. In addition, the coloring material layer of the present invention has a weight of 15 gm or less, preferably 1 to 5 g, m
It would be fine if it were.

[Effects of the Invention] According to the present invention, in a heat-sensitive transfer recording medium having a colorant layer containing a colorant and a heat-melting substance on a heat-resistant polymer film support, the colorant in the colorant layer is a dye. In addition, since the heat-melting substance is a wax that can dissolve the dye, the above-mentioned object of the present invention can be achieved, and in particular, by using the dye and a specific hook in combination,
It is now possible to increase the covering power of the coloring material layer and make the coloring material layer relatively thin in order to obtain the necessary density.
As a result, the object of the present invention has been successfully achieved. Furthermore, high sensitivity enables high-speed recording (printing).

[Examples] Examples are given below, but the embodiments of the present invention are not limited thereto. In addition, "department" used below means "
Parts by weight.

Example 1 The following colorant layer composition was coated on a 4 gm thick polyethylene terephthalate film support to give a dry film thickness of 21 parts m to obtain thermal transfer recording medium sample (2) of the present invention.

Coloring material layer composition Carnauba wax 50 parts Amid wax (Kao Amide C9 manufactured by Kao Atlas Co., Ltd.)
(Solubility of the following dye: 5.5% by weight) 50 parts oleic acid
30 parts Ethylene-vinyl acetate copolymer 10 parts Eisenspiron Black M) I (manufactured by Hodogaya Chemical Co., Ltd.) 10 parts Comparative Example 1 In the coloring material layer composition of sample 1, amide wax was not used, and 50 parts of paraffin wax was used. A comparative thermal transfer recording medium sample 1 was obtained with the only difference being that .

Comparative Example 2 In the coloring material layer composition, Eisenspiron blank Ml (
A comparative thermal transfer recording medium sample (2) was obtained in the same manner except that carbon black (RAVEN 1250, manufactured by Columbia Carbon Co., Ltd.) was used instead.

”-The thermal transfer recording medium samples obtained in the Examples and Comparative Examples were printed on a thermal printer (heating element density: 8 dots/m
A prototype machine equipped with a 1-m thin model line thermal head. ) was printed on paper (Beck smoothness: 500 sec) by varying the applied energy, and the light reflection density of the printed dye transfer image was measured using a reflection densitometer (manufactured by Konishiroku Photo Industries Co., Ltd.). The results shown in the figure were obtained.

Comparative Example 3 Since the concentration of the comparative sample (1) was low, a sample (2) was prepared in which the only difference was that the film thickness of the sample (2) was changed to 3.57 parts m to make it the same as the sample (0) of the present invention.

Comparative Example 4 In addition, another sample was prepared with the only difference being that the amount of carbon black added was increased by 1.5 times from Comparative Sample (1), and the film thickness was the same, 2p and 2m.

The printing results for these samples (Excellent and ■) are also shown in FIG.

As is clear from FIG. 1, sample (2) of the present invention can be printed with low energy and has extremely high sensitivity. In addition, sample ① of the present invention has a Bekk smoothness of 500s.
As a result of printing a checkerboard pattern on EC approval paper and observing it with a magnifying glass, it shows a checkerboard pattern, whereas the comparison sample ■ shows a checkerboard pattern.
Although a dye transfer image with high density was obtained, the resolution of the dye transfer image was significantly deteriorated.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between applied energy and reflection density for each sample in Examples. Special 31 Applicant Konishiroku Photo Industry Co., Ltd. Agent Nobuaki Sakaguchi (and 1 other person)

Claims (1)

[Claims] In a heat-sensitive transfer recording medium having a colorant layer containing a colorant and a heat-melting substance on a heat-resistant polymer film support,
A heat-sensitive transfer recording medium characterized in that the coloring agent of the coloring material layer is a dye, and the heat-melting substance is a wax capable of dissolving the dye.