JPH03184895A - Releasable thermal transfer sheet - Google Patents

Abstract

PURPOSE:To form a uniform dye layer, to enhance the releasability of the dye layer and an image receiving sheet and to obtain a transfer image of high quality by constituting the dye layer of a thermal transfer sheet of two layers and adding a lubricant and/or a release agent only to the surface dye layer thereof. CONSTITUTION:Two dye layers are formed and a release agent (a lubricant and/or a release agent) is contained in the surface dye layer thereof. The first dye layer containing no release agent is formed by dissolving or dispersing a sublimable dye, a binder resin and arbitrary components in a proper solvent to prepare dye layer forming paint or ink and applying the paint or ink to a base film to dry the same. Continuously, the second dye layer is formed in the same way using a composition prepared by adding the release agent such as a silicone compound, a phosphoric ester type surfactant or wax to the previous paint or ink. The content of the release agent is set to 0.1 - 30% by wt. of the surface dye layer.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a releasable thermal transfer sheet, and more specifically, it is useful for a thermal transfer method using sublimable dyes (thermally transferable dyes), and The object of the present invention is to provide a releasable thermal transfer sheet that has excellent releasability between layers and an image-receiving sheet, and can provide monocolor or full-color images with excellent image density.

(Prior art and its problems) Inkjet methods, thermal transfer methods, etc. have been developed as methods for providing excellent monochrome or full-color images simply and at high speed in place of conventional general printing methods. Among these, the so-called sublimation thermal transfer method, which uses sublimable dyes, is the most excellent as it has excellent continuous gradation properties and provides full-color images comparable to color photographs.

The thermal transfer sheet used in the above-mentioned sublimation type thermal transfer method has a dye layer containing a sublimable dye formed on one side of a base film such as a polyester film, and a dye layer containing a sublimable dye on one side of the base film to prevent the thermal head from sticking. A heat-resistant layer provided on the other side is generally used.

The dye layer surface of such a thermal transfer sheet is placed on an image-receiving sheet having a dye-receiving layer made of polyester resin, etc., and the dye in the dye layer is transferred to the image-receiving sheet by heating the image-wise image from the back side of the thermal transfer sheet with a thermal head. The desired image is then formed.

In the thermal transfer method as described above, very high-speed thermal transfer is required, and the heating by the thermal head is performed in a very short time (msec unit), so the thermal head is required to have a high temperature.

As a result, when the temperature of the thermal head is raised, the binder forming the dye layer softens and sticks to the image receiving sheet, causing problems such as adhesion between the thermal transfer sheet and the image receiving sheet. When these layers are peeled off, the dye layer is peeled off and transferred as it is to the surface of the image-receiving sheet, which causes a problem called abnormal transfer.

One way to solve the above problems is to add a lubricant and/or release agent to the dye-receiving layer of the image-receiving sheet. When laminating a surface protective layer such as a transparent film on an image, there is a problem in that it is difficult to adhere the surface protective layer.

To solve this problem, a method has been proposed in which the lubricant and/or release agent is not added (or reduced) to the dye-receiving layer and the lubricant and/or release agent is added to the dye layer of the thermal transfer sheet. There is. However, with this method, when forming the dye layer, the coating solution for the dye layer is repelled by the base film, making it difficult to form a uniform dye layer, resulting in color unevenness in the formed image. There is a problem that occurs. Furthermore, there is a problem in that the adhesiveness between the formed dye layer and the base film is low, and so-called abnormal transfer, in which the dye layer itself peels off and transfers to the image receiving sheet during thermal transfer, tends to occur.

Therefore, an object of the present invention is to provide a thermal transfer sheet that can provide images of excellent quality without causing the above-mentioned problems.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention provides a thermal transfer sheet in which a dye layer containing a dye that is transferred by heating and transferred to an image receiving sheet is formed on a base film, in which the dye layer is composed of two layers,
This is a releasable thermal transfer sheet characterized in that only the dye layer on the surface contains a lubricant and/or a release agent.

(Function) The dye layer of the thermal transfer sheet has a two-layer structure, and by containing a lubricant and/or a release agent (hereinafter simply referred to as a release agent, etc.) only in the dye layer on the surface, the coating for forming the dye layer can be used. A uniform dye layer is formed without the problem of repelling when applying the liquid, and furthermore, the releasability between the dye layer and the image receiving sheet is improved without any abnormal transfer during thermal transfer, and high quality is achieved. It is possible to provide a transferred image of

(Preferred Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

The thermal transfer sheet of the present invention is basically formed by forming a dye layer on a base film in the same manner as in the prior art.
The dye layer has a two-layer structure, and is characterized in that only the dye layer on the surface contains a release agent and the like.

The base film of the thermal transfer sheet of the present invention as described above may be any conventionally known film as long as it has a certain degree of heat resistance and strength, for example, 0.5 to 50.
um, preferably about 3 to 10 μm thick paper, various processed papers, polyester film, polystyrene film, polypropylene film, polysulfone film, aramid film, polycarbonate film, polyvinyl alcohol film, cellophane, etc. Particularly preferred is polyester. It's a film. These base films may be sheet-fed or continuous films, and are not particularly limited.

The dye to be used is not particularly limited, and any dye used in conventionally known thermal transfer sheets can be effectively used in the present invention. For example, some preferred dyes include MS Red G, Ma
crolex Red Violet R, Ceres
Red7B, Samaron Red HBSL,
Examples include Re5olin Red F3BS, and
As a yellow dye, Holon Brilliant Yellow 6G
Examples of blue dyes include Kayacet Blue 14, Waxolin Blue AP-FW, Holon Brilliant Blue S-R, and MS Blue 100.

As the binder resin for supporting the above-described dye, any conventionally known binder resin can be used, and preferred examples include ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate,
Examples include cellulose resins such as cellulose acetate butyrate, vinyl resins such as polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acecool, polyvinyl pyrrolidone, polyacrylamide, and polyester. Among these, cellulose resins, acetal From the viewpoint of heat resistance, dye migration properties, etc., polyester-based dyes, butyral-based dyes, butyral-based dyes, and polyester-based dyes are preferred.

In the present invention, the dye layer is formed into two layers, and the surface dye layer contains a release agent and the like.

As such a release agent, any of the known release agents conventionally used in release papers and the like that does not interfere with the thermal transfer of the dye in the dye layer can be used. A mold release agent that does not hinder the thermal transfer of the dye in the dye layer can be easily selected and used by preparing a thermal transfer sheet using various mold release agents and performing a thermal transfer test.

Preferred compounds for the present invention include silicone compounds, phosphate ester surfactants, waxes, etc. For example, silicone compounds include silicone alkyds, silicone alkyds,
Examples include silicone graft polymers (acrylic resins, polyester resins, styrene resins, urethane resins), alkyl-modified silicones, fluorofatty acid-modified silicones, phenyl group-containing silicones, fatty acid-modified silicones, polyether-modified silicones, etc. Particularly preferred among these are One is a silicone graft polymer. or,
Examples of the phosphoric acid ester compound include sodium phosphate salt, and examples of the wax include polyethylene wax and carnauba wax.

The content of the release agent and the like is preferably from 0.1% to 30% by weight, preferably from 0.1% to 20% by weight, based on the dye layer on the surface.

Furthermore, the dye layer may also contain various other conventionally known additives as required.

Of the two dye layers described above, the dye layer that does not contain a release agent is preferably prepared by adding the sublimable dye, binder resin, and other optional components to an appropriate solvent and dissolving or dispersing each component. A paint or ink for forming a dye layer is prepared, and this is applied onto the above base film and dried to form the dye layer.On the other hand, the dye layer containing a release agent, etc. is prepared by adding a release agent, etc. to the same coating solution. Form in the same way using the added .

The dye layer formed in this way has a total thickness of about 0.2 to 5.0 μm, preferably about 0.4 to 2.0 μm, and the thickness of each dye layer is 10 to 90% of the total thickness.
It can be as thick as .

It is also preferred that the sublimable dye in the total dye layer is present in an amount of 5 to 90% by weight, preferably 10 to 70% by weight of the weight of the dye layer.

The dye layer to be formed may be formed by selecting one color from among the dyes mentioned above when the desired image is a monochrome image, or by selecting an appropriate color from among the dyes when the desired image is a full color image. Cyan, magenta and yellow (and black if necessary) are selected to form yellow, magenta and cyan (and black if necessary) dye layers.

The image-receiving sheet used to form an image using the thermal transfer sheet as described above may be of any type as long as its recording surface has dye-receptive properties for the above-mentioned dyes. If the material is paper, metal, glass, synthetic resin, etc., which does not have a dye, a dye-receiving layer may be formed on at least one surface thereof.

As the means for applying thermal energy used when performing thermal transfer using the above-mentioned thermal transfer sheet and image-receiving sheet as described above, any conventionally known means for applying thermal energy can be used. For example, thermal printers (for example, 5 to 100 mJ/mr by controlling the recording time using a recording device such as a video printer VY-100).
r? By applying a certain amount of thermal energy, the desired image is formed.

(Effect) According to the present invention as described above, the dye layer of the thermal transfer sheet can be
By having a layered structure and containing a release agent etc. only in the dye layer on the surface, a uniform dye layer can be formed without causing the problem of repelling during night coating.
Furthermore, the releasability between the dye layer and the image-receiving sheet is improved without causing any abnormal transfer during thermal transfer, and a high-quality transferred image can be provided.

(Example) Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. In the text, parts or percentages are based on weight unless otherwise specified.

Example 1 The following dye layer forming ink (A) was applied to the surface of a 9 μm thick polyethylene terephthalate film (S-PE, manufactured by Toyobo Co., Ltd.) which had been heat-resistant treated on the back side of the surface on which the dye layer was to be formed as a base film. The first dye layer was formed by coating and drying with Myabah #8 to a dry thickness of 0.5 g/rrr, and then the following ink (B) was similarly coated and dried to obtain a thickness of 0.5 g/rrr. A second dye layer of 0.5 μm was formed to prepare a thermal transfer sheet of the present invention.

Ink (A) KST-B-136 (manufactured by Nippon Kayaku) 5 parts polyvinyl butyral resin (manufactured by Block Chemical Industry Co., Ltd., S-LEC BX-1
) 5 parts methyl ethyl ketone
30 parts toluene
30 parts KST-B-136 (manufactured by Nippon Kayaku) 5 parts 2 Mold release agent (US-350, manufactured by Toagosei) 0, 5 parts Polyvinyl butyral resin (manufactured by Block Chemical Co., Ltd., S-LEC BX- 1) 5 parts methyl ethyl ketone 30 parts toluene
30 parts Example 2 In place of the release agent in ink B of Example 1, a release agent (
A thermal transfer sheet of the present invention was prepared in the same manner as in Example 1 using the same amount of fluorine-modified silicone resin FLloo (Shin-Etsu Chemical Co., Ltd.).

Example 3 In place of the release agent in ink B of Example 1, a release agent (
Polyethylene wax, manufactured by Astor Wax Company, USA, M
A thermal transfer sheet of the present invention was prepared in the same manner as in Example 1 using 0.3 parts of F8F).

Comparative Example 1 Using only ink A in Example 1, the thickness was 1.0μ.
A thermal transfer sheet of a comparative example was prepared in the same manner as in Example 1.

Preparation of image-receiving sheet Next, synthetic paper (Yubo FP manufactured by Tamago Yuka Co., Ltd.) was used as a base film.
Coating liquids (A) and (B) having the following compositions were applied to one side of the coating at a drying rate of 4.5 g/n, respectively, and dried at 100°C for 30 minutes. Two types of image-receiving sheets were obtained for use in the invention and comparative examples.

20 parts methyl ethyl ketone 40 parts toluene
40 parts direct solution Vinyl chloride-vinyl acetate copolymer (#1000A, manufactured by Denki Kagaku Kogyo) 20 parts Amine-modified silicone oil (manufactured by Shin-Etsu Chemical, KF393)
0.2 parts epoxy modified silicone oil (manufactured by Shin-Etsu Chemical, X-22-343)
0.2 parts methyl ethyl ketone
40 parts toluene 40 parts Thermal transfer test The thermal transfer sheets of the Examples and Comparative Examples and the image receiving sheet were placed one on top of the other with the dye layer and the image receiving layer facing each other, and a thermal head (KMT-85-6
, MPD2), head applied voltage 12, OV, applied pulse width 16.0 m5ec, /1ine to 1 m5
A step pattern in which the step pattern is sequentially decreased by ec, 61 ine/mm in the sub-scanning direction (33,3 m5 ec, /1 ine)
Thermal head recording was performed under these conditions.

As a result, in the case of the thermal transfer sheets of Examples, the dye layer did not directly transfer to the image-receiving layer surface during recording, and the peelability between the transfer sheet and the image-receiving sheet after recording was also good. Furthermore, the recorded image showed clear color development.

On the other hand, when the thermal transfer sheet of the comparative example was used, so-called abnormal transfer in which the dye layer was transferred as a layer occurred in some parts, and a good image could not be obtained.

5 Example 3 In place of the release agent in Ink B of Example 1, the following No. 1
The thermal transfer sheet of the present invention was obtained in the same manner as in Example 1 except that the release agent shown in the table was used, and the peelability during printing was examined in the same manner as in the thermal transfer test, and the results shown in Table 1 below were obtained. It was done.

(Margin below)

Claims (3)

[Claims] (1) In a thermal transfer sheet in which a dye layer containing a dye that is transferred by heating and transferred to an image receiving sheet is formed on a base film, the dye layer consists of two layers, and only the surface dye layer has a lubricant. A releasable thermal transfer sheet characterized by containing a release agent and/or a release agent. (2) The lubricant and/or mold release agent is a silicone compound,
The releasable thermal transfer sheet according to claim 1, which is a phosphate ester surfactant, wax, or the like. (3) The releasable thermal transfer sheet according to claim 1, wherein the content of the lubricant and/or release agent is 0.1% to 30% by weight of the dye layer on the surface.