JPH0624165A - Thermally transcribed sheet and preparation of the same - Google Patents

Abstract

PURPOSE:To obtain directly from electric signals a coloring image having a continuous gradation like a photograph, high concentration, and good transparency, prevented from discoloration even after storage for a long period, keeping a high resolution and to provide a combination between a thermal transcription sheet and a thermally transcribed sheet which prevents peeling and migration of a thermal transcription layer to a thermally transcribed layer and fusion between the thermal transcription sheet and the thermally transcribed sheet during thermal transcription. CONSTITUTION:In the preparation of a thermally transcribed sheet which is used in combination with a thermal transcription sheet having a thermal transcription layer containing a coloring material that can be thermally transcribed and has a receiving layer which receives the migration of a coloring material by contacting and heating the thermal transcription layeron its substrate, a suspension film is placed on the substrate which contains two or more kinds of suspensions comprising at least a resin and water, and then the suspension film is dried to form the receiving layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-transferable sheet, and more specifically, a heat-transferable sheet used in combination with a heat-transferable sheet, in which heat-printing is carried out according to image information by a thermal head or a laser, and its production. Concerning the law.

[0002]

2. Description of the Related Art In order to obtain an image according to image information by a thermal head or a laser, a heat-sensitive color developing paper has been mainly used. In this heat-sensitive color-developing paper, a colorless or light-colored leuco dye and a developer provided on the base paper are brought into contact with each other by heating to obtain a color-developed image. As such a color developer, a phenolic compound, a zinc salicylate derivative, rosin and the like are generally used. However, the above-mentioned thermosensitive coloring paper has a fatal defect that the obtained colored image is erased when stored for a long period of time, and color printing is limited to two colors and has continuous gradation. It was not possible to obtain a color image.

On the other hand, in recent years, heat-sensitive transfer paper, in which a heat-melting wax layer having a pigment dispersed therein is provided on a base paper, has begun to be used. When the heat-sensitive transfer paper and the heat-transferred material are superposed and heat printing is performed from the back surface of the heat-sensitive transfer paper, the wax layer containing the pigment is transferred onto the heat-transferred paper to obtain an image. According to such a printing method, a durable image can be obtained, and a multicolor image can be obtained by printing a plurality of times using a thermal transfer paper containing pigments of three primary colors,
It is not possible to obtain photographic-like images with essentially continuous tone.

By the way, in recent years, there has been an increasing demand for directly obtaining an image such as a photograph from an electric signal, and various attempts have been made. One of such attempts is a method of transferring an image onto a CRT and photographing it with a silver salt film. However, when the silver salt film is an instant film, there is a drawback that running cost increases, and silver is also used. When the salt film is a 35 mm film, there is a drawback that it is not immediate because development processing is required after photography. As another method, an ink-pact ribbon method or an inkjet method has been proposed, but the former has a drawback that the image quality is poor, and the latter requires image processing, so that an image like a photograph cannot be easily obtained. It has the drawback of being difficult.

In order to solve such a drawback, a thermal transfer sheet provided with a sublimable disperse dye layer having a property of transferring by heating is used in combination with a heat transferable sheet, and the sublimable disperse dye is controlled while being controlled. A method has been proposed in which the image is transferred onto a thermal transfer sheet to obtain a photographic image with gradation. According to this method, an image having continuous gradation can be obtained from a television signal by a simple process, and a device used at that time is not complicated, and therefore, it is attracting attention. As one of the conventional techniques close to such a method,
A dry transfer printing method of polyester fibers is mentioned.This dry transfer printing method is a dye obtained by dispersing or dissolving a coloring material such as a sublimable disperse dye in a synthetic resin solution to form a dye on a thin paper. This is a method in which a thermal transfer sheet is obtained by coating and drying, and the thermal transfer sheet is superposed on the polyester fiber which is the thermal transfer sheet, and heated in close contact, and the disperse dye is dyed on the polyester fiber to obtain an image.

However, it is not possible to obtain a high density color image by superposing the thermal transfer sheet and the thermal transfer sheet made of polyester fiber as described above and printing them by heating with a thermal head or the like. The reason is that the surface smoothness of the polyester fiber cloth is not good, but it is considered to be mainly due to the following reason. That is, in the usual dry transfer printing method or wet transfer printing method, transfer of the sublimable dye onto the polyester fiber cloth is carried out for a sufficient heating time, whereas heating by a thermal head or the like is usually extremely short. Therefore, this is because the coloring material does not sufficiently migrate onto the fiber cloth.
By the way, in the dry transfer printing method, at 200 ℃ for about 1 minute,
While the transfer of coloring material is achieved by heating,
The heating by the thermal head is as short as several msec at 400 ° C.

The present inventors have found the following facts as a result of researches aimed at achieving the above drawbacks mainly by improving the heat transferable sheet.

When clay-coated paper or synthetic paper is used as the heat transfer sheet, the color material transferred from the heat transfer sheet cannot be sufficiently received, and therefore a high density color image cannot be obtained. There is.

On the other hand, when a heat transferable sheet having a low melting point synthetic resin as a receiving layer is used, the synthetic resin layer itself has thermal adhesiveness due to the action of heat and pressure applied to the thermal transfer sheet. The thermal transfer layer of the thermal transfer sheet may be transferred onto the thermal transfer sheet, which has the drawback that the clarity and resolution of the obtained image are impaired.

Further, when a heat transferable sheet having a synthetic resin having a low glass transition temperature as a receiving layer is used, the color material thermally transferred onto the heat transferable sheet is sufficiently fixed and a high density color image is temporarily obtained. However, it was found that the coloring material thermally diffused with time and the image was disturbed. On the other hand, it has been found that when the receiving layer of the heat transfer sheet is made of a synthetic resin having a high glass transition temperature, the above-mentioned thermal diffusion can be prevented, but the fixing property of the color material transferred from the heat transfer sheet is poor. Although it is an extreme example, if a soft polyvinyl chloride resin sheet containing an ester group-containing plastic such as dioctyl phthalate is used as the receiving layer of the heat-transferable sheet, a high-concentration color-developed image can be obtained immediately after thermal transfer. However, since the coloring material dissolves in the plasticizer and diffuses in the sheet, the color image obtained is usually unclear when left at room temperature for about a week, and it is virtually impossible to store the color image. It turned out to be possible.

[0011]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above-mentioned drawbacks associated with the prior art, and to achieve the following objects.

A) Obtaining a color image having continuous gradation like a photograph directly from an electric signal.

B) To obtain a highly concentrated and highly transparent colored image, and to obtain a clear and highly resolved image without decolorization of the colored image even when stored for a long period of time.

C) To provide a combination of a heat transfer sheet and a heat transfer sheet which does not cause the transfer of the heat transfer layer to the heat transfer layer during the heat transfer so that the heat transfer sheet does not adhere to the heat transfer sheet. .

In order to achieve the above objects, the method for producing a heat transferable sheet according to the present invention is used in combination with a heat transfer sheet having a heat transfer layer containing a color material capable of heat transfer, and is brought into contact with the heat transfer layer. In producing a thermal transfer sheet having a receptive layer that receives a transfer of a coloring material by heating on a thermal transfer sheet substrate, a dispersion coating film containing at least two kinds of dispersion liquids containing at least a resin and water is used. It is characterized in that the receiving layer is formed by providing the coating film on the base material and then drying the dispersion coating film.

The present invention will be described in more detail below.

The heat transferable sheet according to the present invention is constructed by providing a receiving layer on a base material.

As the base material, in addition to plain paper, various synthetic papers, a flexible thin layer sheet such as a plastic film can be used. Since this base material has a role of holding the receiving layer and heat is applied at the time of thermal transfer, it is desirable that the base material has a mechanical strength that does not hinder the handling even in a heated state.

The receiving layer is formed by providing a dispersion coating film comprising at least two kinds of resins and water on a substrate and then drying.

As the resin as the dispersoid constituting the dispersion with water, (a) a resin having a single type of dyeability,
(B) A mixture of the same type of resin having a high dyeability and a low dyeability, and (c) two or more resins having at least one dyeability and incompatible with each other. A mixture of
Etc. can be used.

It is considered that the size of the dyeing ability of the resin is substantially proportional to the physical properties of the resin, particularly the glass transition temperature. Generally, it can be said that a resin having a glass transition temperature of −100 ° C. to 20 ° C. generally has a low dyeing ability, and a resin having a glass transition temperature of 40 ° C. or higher generally has a high dyeing ability.

Usually, different kinds of resins have poor compatibility with each other, and the compatibility may be lowered even in a solvent, so that a uniform coating film may not be obtained. However, it is necessary to mix the resins using water dispersion. This makes it possible to obtain a uniform coating film.

In the present invention, the term "dispersion liquid" includes both a liquid-liquid dispersion system (emulsion) and a liquid-solid dispersion system (suspension).

The following are preferred specific examples of the above resin-water dispersion. (A) Natural rubber latex (concentrate of natural rubber sap) (b) Synthetic rubber latex (aqueous dispersion of synthetic rubber obtained by emulsion polymerization) SBR (styrene / butadiene copolymer) latex,
Polychloroprene latex, polybutadiene latex, butyl rubber (polybutene) latex, etc. (C)
Synthetic resin emulsion (Aqueous dispersion of synthetic resin obtained by emulsion polymerization) Polyacrylic ester emulsion, polyvinyl acetate emulsion, ethylene / vinyl acetate copolymer emulsion, polystyrene emulsion, polyvinyl chloride emulsion, etc. (D) Synthetic resin aqueous dispersion (synthetic resin solution or synthetic resin aqueous dispersion obtained by dispersing synthetic resin melt in water) Polyester aqueous dispersion, polyurethane aqueous dispersion, polyethylene aqueous dispersion and the like.

The above-mentioned resin water dispersion may contain a dispersant for stabilizing the dispersion. Specific preferred examples of the dispersant to be added include the following. (I) Emulsifiers Anionic surfactants such as carboxylates, sulfonates, sulfates, phosphates, phosphonates, amine salts, quaternary ammonium salts, phosphonium salts, sulfonium salts, etc. Cationic surfactant,
Amphoteric surfactants such as betaine and sulfobetaine, nonionic surfactants such as fatty acid monoglycerin ester and fatty acid polyglycol ester. (II) Protective colloid Polyvinyl alcohol, ethylene / vinyl alcohol copolymer, polyacrylic acid, polymethacrylic acid, hydroxyethyl cellulose, hydroxypropyl cellulose,
Methyl cellulose, ethyl cellulose, etc. (III) Self-emulsifying resin A resin such as a polar group-containing polyurethane which has a polar property and which is localized on the particle surface to impart dispersion stability.

The composition of the above-mentioned resin aqueous dispersion has a weight ratio of the resin component of 20 to 70%, more preferably 30 to 60%, and water content.
It is in the range of 30 to 80%, more preferably 40 to 70%. The dispersant is added in a weight ratio of 0.1 to 10%, preferably 1 to 5%, relative to the resin component.

Various additives may be added to the resin aqueous dispersion, but those components should be selected from those which do not interfere with the fixing of the dye transferred to the thermal transfer sheet during heating. . Examples of such an additive include a cured product of a silicone compound, such as a cured product of an epoxy-modified silicone oil and an amino-modified silicone oil, which enhances releasability from the thermal transfer sheet.

To form the receiving layer with the resin aqueous dispersion having the above composition, first, a resin aqueous dispersion coating film is formed on a substrate by an appropriate printing method or coating method, for example, wire bar coating, and the like. This is done by drying. The thickness of the receptive layer may be appropriately selected depending on the type of the substrate, etc., but usually the thickness after drying is 1 to 20.
It is desirable that the thickness is in the range of μm, preferably 2 to 10 μm.

Further, if necessary, a release layer may be formed on the surface of the receiving layer to enhance the release property from the thermal transfer sheet. A cured product of a silicone compound, for example, a cured product of an epoxy-modified silicone oil and an amino-modified silicone oil, is preferably used as the composition for forming such releasability.

The heat transferable sheet produced by the above-mentioned method is used in combination with the heat transfer sheet.

A typical thermal transfer sheet is constructed by providing a thermal transfer layer on one surface of a support, and when the thermal transfer layer is heated, the coloring material contained therein migrates onto the thermal transfer sheet. It is like this.

As such a coloring material, about 150-40
Examples thereof include disperse dyes having a relatively small molecular weight of about 0, oil dyes, certain basic dyes, and intermediates that can be converted into these dyes. Among these, thermal transfer temperature, thermal transfer efficiency, hue, It is selected and used in consideration of color rendering properties and weather resistance.

The above coloring material is provided on a support by being dispersed in an appropriate synthetic resin binder forming a thermal transfer layer. As such a synthetic resin binder, usually,
It is preferable to select a material that has high heat resistance and does not hinder the transfer of the coloring material that occurs when heated. For example, the following materials are used. (I) Cellulose-based resin Ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxycellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, cellulose acetate butyrate, etc. (Ii) Vinyl resin Polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl pyrrolidone, polyester, polyacrylamide and the like.

Among the above synthetic resin binders, polyvinyl butyral resin or cellulose resin is preferable from the viewpoint of heat resistance.

To provide the thermal transfer layer on the support, the coloring material and the synthetic resin binder are kneaded together with a solvent or a diluent to prepare a dye composition for the thermal transfer layer, which is applied to the support by an appropriate printing method or coating method. Should be provided in.
If desired, any additive may be added to the composition for thermal transfer layer.

The basic constitution of the thermal transfer sheet is as described above. However, when the surface of the support is directly heated by a contact type heating means such as a thermal head, the thermal transfer layer of the support is provided. By providing a slippery layer containing a lubricant such as wax or a release agent on the non-coated side, it is possible to prevent fusion between the heating means such as a thermal head and the support and improve the slip.

The thermal transfer sheet and the thermal transfer sheet prepared as described above are faced to each other so that the thermal transfer layer of the thermal transfer sheet and the receiving layer of the thermal transfer sheet are in contact with each other, and the interface between the thermal transfer layer and the receiving layer responds to image information. By applying the heat energy, the coloring material in the thermal transfer layer can be transferred to the receiving layer according to the heat energy.

[0038]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. Example 1 As a base material, P having a thickness of 9 μm and having one surface subjected to corona treatment
Using ET film (S-PET manufactured by Toyobo), the dye composition for the thermal transfer layer having the following composition is applied by wire bar coating on the surface of the corona-treated film so as to have a dry thickness of 1 μm. And silicone oil on the back (X-41.4003A, made by Shin-Etsu Silicone)
Was applied in a small amount and subjected to back surface treatment to obtain a thermal transfer sheet. Heat transfer layer coating composition Disperse dye (Nippon Kayaku Kayaset Blue 136) 4 parts by weight Ethyl hydroxyethyl cellulose (Hercules)
5 parts by weight Toluene 40 parts by weight Methyl ethyl ketone 40 parts by weight Dioxane 10 parts by weight 150 μm synthetic paper as base material (YUPO-manufactured by Oji Yuka)
FPG-150) was used to apply a coating composition for a heat transferable layer having the following composition on the surface by wire coating so that the thickness when dried was 7 μm, and dried at 60 ° C. for 1 hour. Coating composition for heat transferable layer Bayronal MO-1200 75 parts by weight (solid content inclusion) (Toyobo polyester resin) Aizelax S-1040 25 parts by weight (Hoya Chemical Co. polyurethane dispersion) (solid content inclusion) The coating composition for release layer having the following composition is applied to the surface of the receptor layer formed as described above by wire bar coating so that the thickness when dried is 0.2 μm, and the temperature is 100 ° C. for 1 hour. A heat-transferred sheet was formed by drying. Coating composition for release layer KF-393 (amino-modified silicone oil manufactured by Shin-Etsu Silicon) 3 parts by weight X-22-393 (epoxy-modified silicone oil manufactured by Shin-Etsu Silicon) 3 parts by weight Ethyl alcohol 100 parts by weight Obtained as described above The thermal transfer sheet and the thermal transfer sheet are combined, and thermal transfer is performed by a thermal transfer printer under the conditions of a thermal head output of 1 W / dot, a pulse width of 0.3-4.5 msec, and a dot density of 3 dots / mm. Macbeth RD918 When the optical reflection density of the high color density recording portion was measured with a reflection densitometer, the values of 2 and 1 were obtained.

The thermal transfer-completed thermal transfer sheet and the synthetic paper used as the base material of the thermal transfer sheet are superposed and
When a load of g / cm was applied and the plate was allowed to stand at 60 ° C. for 60 hours, no staining of the synthetic paper due to migration of the dye from the thermal transfer sheet was observed. Further, the thermal transfer image was not disturbed due to the diffusion of the dye inside the heat transfer sheet. Example 2 The same thermal transfer sheet as that obtained in Example 1 and the coating composition for the layer to be thermally transferred in Example 1 were used to prepare Vylonal M.
When thermal transfer was performed in the same manner as in Example 1 by combining with a heat transferable sheet obtained in the same manner as in Example 1 except that D-1200 was excluded, the optical reflection density of the high color density recording portion was 2. We got a value of 0.

When the above-mentioned thermally transferred heat-transferable sheet and the synthetic paper used as the base material of the heat-transferable sheet in Example 1 were overlaid and allowed to stand under the same conditions as in Example 1, the dye from the heat-transferable sheet was dyed. Although the synthetic paper was not contaminated due to the transfer of the dye, the image on the heat-transferred image was slightly disturbed due to the diffusion of the dye inside the heat-transferred sheet. Example 3 Similar to Example 1 except that 2.55 parts by weight of Nippon Kayaku Cassette Red B was used instead of Nippon Kayaku Cassette Blue 136 as the disperse dye of the thermal transfer layer coating composition in Example 1. Then, a thermal transfer sheet was obtained.

A heat transferable sheet was formed in the same manner as in Example 1 except that the composition of the coating composition for the heat transferable layer was changed as follows. Coating composition for heat transfer layer MD-1930 67 parts by weight (Toyobo polyester resin water dispersion (solid content)) ACNAROLL YJ-1100D 33 parts by weight (Okaka Birdish acrylic emulsion (solid content)) ) When the thermal transfer sheet and the thermal transfer sheet obtained as described above were combined and thermal transfer was carried out in the same manner as in Example 1, a value of 1.2 was obtained as the optical reflection density of the high color density portion. It was

The above-mentioned thermally transferred sheet to be thermally transferred and Example 1
When left standing under the same conditions as above, no disturbance of the thermally transferred image due to contamination of the synthetic paper due to migration of dye from the heat transfer sheet and diffusion of dye inside the heat transfer sheet was observed. Example 4 A thermal transfer sheet obtained in the same manner as in Example 1 except that the same thermal transfer sheet as that obtained in Example 1 and the composition of the coating composition for the layer to be thermally transferred in Example 1 were changed as follows. When thermal transfer was carried out in the same manner as in Example 1 in combination with the above, a value of 1.8 was obtained as the optical reflection density of the high color density recording portion. Paint composition for heat transferable layer Acronal YJ-2730D 33 parts by weight (Acrylic emulsion made by Yuka Birdishe (solid content)) 67 parts by weight of VINYSOL DU-230 (Polyamide water dispersion made by Daido Kasei (solid content)) When the heat-transferred sheet having undergone thermal transfer and the synthetic paper used as the base material of the heat-transferred sheet in Example 1 were overlaid and allowed to stand under the same conditions as in Example 1, the synthesis was carried out by migration of the dye from the heat-transferred sheet. Disturbance of the heat-transferred image due to paper stains and stains inside the heat-transferred sheet was not observed. Example 5 A thermal transfer sheet obtained in the same manner as in Example 1 except that the same thermal transfer sheet as that obtained in Example 3 and the composition of the coating composition for the layer to be thermally transferred in Example 1 were changed as follows. When thermal transfer was performed in the same manner as in Example 1 in combination with a sheet, the optical reflection density of the high color density recording portion was 1.1.
I got the value. Heat-transferable layer coating composition Aizerax S-0180 67 parts by weight (Hodogaya Chemical Polyurethane water dispersion (solid content)) Aizerax S-4040N 33 parts by weight (Hodogaya Chemical Polyurethane water dispersion (solid content) Hug))) The above-mentioned thermally transferred thermal transfer sheet and the synthetic paper used as the base material of the thermal transfer sheet in Example 1 were combined and allowed to stand under the same conditions as in Example 1, and the dye from the thermal transfer sheet was obtained. Disturbance of the heat-transferred image due to the contamination of the synthetic paper due to the transfer of the dye and the diffusion of the dye inside the heat-transferred sheet was not observed.

Claims (8)

[Claims] 1. A receiving layer, which is used in combination with a thermal transfer sheet having a thermal transfer layer containing a thermally transferable coloring material and which is transferred to the thermal transfer layer and is subjected to the transfer of the coloring material by heating, is formed on a thermal transfer sheet substrate. In producing the heat-transferable sheet, a dispersion coating film containing at least two kinds of dispersion liquids containing at least a resin and water is provided on the substrate, and then the dispersion coating film is dried to A method for producing a heat-transferable sheet, which comprises forming a receptive layer. 2. A heat transferable sheet obtained by the method of claim 1. 3. The method according to claim 1, wherein the resin is composed of the same type of resin and is a mixture of a resin having a high dyeability and a resin having a low dyeability. 4. The method according to claim 1, wherein the resin comprises a mixture of two or more resins having at least one dyeability and incompatible with each other. 5. The method according to claim 3 or 4, wherein the resin comprises a mixture of synthetic resin emulsions. 6. The method according to claim 3, wherein the resin comprises a mixture of a synthetic resin emulsion and a synthetic resin aqueous dispersion. 7. The method according to claim 3, wherein the resin comprises a mixture of synthetic resin aqueous dispersions. 8. A heat-transferable sheet obtained by the method according to any one of claims 3 to 7.