JPH0911650A - Many-time printing thermal transfer sheet and production thereof - Google Patents

Abstract

PURPOSE: To obtain a many-time printing thermal transfer sheet capable of performing printing free from printing irregularity over many times, not generating such a problem that printing density changes suddenly according to the printing number of times and capable of easily ensuring the coating amt. of a transfer control layer, that is, excellent in coating aptitude. CONSTITUTION: In a many-time printing thermal transfer sheet wherein a hot- melt ink layer 2 and a transfer control layer 3 are laminated to a base material film 1 in this order, the transfer control layer 3 contains no coloring agent and is composed of a hot-melt wax component consisting of a porosity forming resin component and a polyester resin not compatible with the resin component and the porosity forming resin component and the hot-melt wax component are separated in phase.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer sheet having a heat-fusible ink layer used for printing a large number of times, and more specifically, a change in printing density with the number of times printing is used is small and a resolution is high. The present invention relates to a thermal transfer sheet for excellent multi-time printing and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, as a thermal transfer recording medium used in a thermal printer, a facsimile or the like, a thermal transfer sheet having a heat-fusible ink layer provided on one surface of a base film has been used. A conventional thermal transfer sheet uses a base material film such as capacitor paper or paraffin paper having a thickness of about 10 to 20 μm or a plastic film such as polyester or cellophane having a thickness of about 3 to 20 μm. A heat-meltable ink layer is formed by applying a heat-meltable ink prepared by mixing a wax with a colorant such as a pigment or a dye. Then, a predetermined portion is heated and pressed from the back side of the substrate film by a thermal head, and the heat-melting ink layer in the portion corresponding to the printing portion of the heat-melting ink layer is transferred to the printing paper to perform printing. .

However, in such a conventional thermal transfer sheet, since the heat-meltable ink layer at the portion heated and pressed by the thermal head is transferred to the printing paper by one use, the same portion is transferred. However, there is a problem that the printing is possible only once, the consumption of the thermal transfer sheet is large, the running cost is high, and it is not economical.

Therefore, various thermal transfer sheets that can be used many times have been developed. For example, (1) JP-A-54-
No. 68253, JP-A-55-105579, and the like, a base film as disclosed in JP-A-55-105579 is coated with a coating liquid in which a porous-forming resin component and a heat-meltable ink component are mixed and dried, Forming a microporous layer and a heat-melting ink at the same time, or applying a heat-melting ink on the microporous layer and drying it to cause the heat-melting ink to sink into the microporous layer, etc. To gradually exude the heat-meltable ink, (2) JP-A-3-15
Ink spillage is achieved by providing a heat-meltable ink layer on a substrate film as disclosed in Japanese Patent No. 595 and a fine porous layer containing a heat-meltable ink having poor affinity with a resin thereon. What controls the amount, (3) Japanese Patent Laid-Open No. 5-2
No. 46156, and a method of mixing a porosity-forming resin component and thermofusible particles having a releasing action with respect to the resin component, and determining the pore size of the porosity based on the particle size of the fusible particles. and so on.

Further, (4) Japanese Patent Application Laid-Open No. 2-127083 describes a method of forming a fine porous layer by melting a porous-forming resin component and a heat-meltable ink component in a common solvent. Further, (5) JP-A-6-143845 discloses that a porous-forming resin is dissolved in a volatile solvent and dried with air having a relative humidity in a specific range under drying conditions.
A method of forming a porous membrane is described.

[0006]

However, in the case of using the thermal transfer sheet as described in (1), since the heat-meltable ink is fused to the fine porous eyes with repeated printing, the ink outflow amount decreases. Along with that, there is a drawback that the print density decreases. Further, the thermal transfer sheet as in (2) is a fine porous material containing a colorant by applying and drying a coating liquid in which a resin component for forming a porosity and a heat-meltable ink component having a poor affinity with the resin are mixed and dried. When a layer is formed, carbon or the like is mixed in the resin for forming the porosity, and the mechanical strength of the fine porous layer decreases, so that the pore size of the porous layer cannot be increased or the fine porous layer peels off during printing. Occurs, causing a problem that the entire ink layer is transferred.

Further, the resin component for forming porosity as in (3) and the heat-fusible particles having a releasing effect on the resin component are mixed, and the pore size of the porous material is determined by the particle size of the heat-fusible particles. According to the method, it is difficult to control the particle diameter of the heat-meltable particles, and it is difficult to control the pore diameter of the porous material because the heat-meltable particles aggregate. Therefore, the transfer amount of the ink becomes uneven, and the printing unevenness appears especially in the printing of the solid portion.
In addition, the surface of the heat-meltable particles is covered with the resin for forming the porosity, and the formation of the porosity is unstable in many cases where the holes do not penetrate. In the initial printing, since the porous pores are not completely opened, problems such as low initial printing density occur. This tendency is particularly remarkable when a releasing resin or the like is mixed.

Further, the solubility of each component in the solvent can be increased only by the method of dissolving the porous resin component and the heat-melting substance component in a common solvent as in (4) to form the fine porous layer. Since it is not good, the solid content ratio of the ink for forming the fine porous layer is low, and a large amount of solvent is required to obtain the required coating amount, which is a problem in manufacturing cost. In addition, when the solvent is a solvent such as toluene that easily dissolves the wax, there is a problem that the lower heat-meltable ink layer is often dissolved and destroyed. In addition, as in (5), the method for forming a porous film by dissolving the porous-forming resin in a volatile solvent and drying it with air having a relative humidity of a specific range under the drying conditions If the (temperature, humidity) is not constant and changes, it is difficult to keep applying the air under the same conditions, and it is very difficult to control the size of the pore diameter.

Therefore, an object of the present invention is to solve the above-mentioned drawbacks, to enable printing without printing unevenness a number of times, and to decrease or increase the printing density drastically with the number of printings. It is an object of the present invention to provide a thermal transfer sheet for multi-use printing, which is free from the problems and can easily secure the coating amount of the transfer control layer, that is, has excellent coating suitability, and a method for producing the same.

[0010]

In order to achieve the above object, the thermal transfer sheet of the present invention comprises a base film, a heat-fusible ink layer, and a transfer control layer, which are laminated in this order for multiple printing. In the thermal transfer sheet, the transfer control layer comprises a resin component for forming a porosity, containing no colorant, and a heat-melting wax component made of a polyester resin incompatible with the resin component. A thermal transfer sheet for multi-use printing is characterized in that a component and a heat-meltable wax component are phase-separated. Further, the above-mentioned transfer control layer is characterized by containing a medium-chain linear saturated dibasic acid short-chain linear saturated diol oligoester as a heat-melting wax component. In addition, the above transfer control layer,
It is characterized by containing a release agent.

Further, in the method for producing a thermal transfer sheet for multi-printing in which a heat-fusible ink layer and a transfer control layer are laminated in this order on a substrate film, the transfer control layer does not contain a coloring agent, The resin component for forming a porosity and the heat-melting wax component consisting of a polyester resin incompatible with the resin component, the resin component for forming a porosity and the heat-melting wax component are dissolved in a solvent and mixed, A coating liquid in which the resin component and the wax component are incompatible is applied onto the heat-meltable ink layer and then dried, whereby phase separation of the resin component for forming a pore and the heat-meltable wax component is performed. It is characterized in that a transfer control layer utilizing is used.

[0012]

The function of the transfer control layer in the thermal transfer sheet of the present invention is
It is composed of a resin component for forming a porosity and a heat-melting wax component made of a polyester resin which is incompatible with the resin component without containing a colorant, and the resin component for forming a porosity and the heat-melting wax component are used as a solvent. Formed in a state in which the resin component and the heat-meltable wax component are phase-separated by dissolving and mixing the coating liquid in which the resin component and the wax component are incompatible To be done. That is, when the transfer control layer forming coating liquid is applied, the resin component and the heat-meltable wax component can be stably applied in a good compatible state. After coating, the solvent is evaporated during drying and the thermal transfer sheet is formed in a state where the resin component and the heat-meltable wax component are phase-separated. Further, the heating at the time of printing melts the heat-melting wax component to form pores for controlling the outflow amount of the heat-melting ink. Here, the size of the pores can be controlled by adjusting the mixing ratio of the porosity forming resin component and the wax component. Therefore, by carrying out this adjustment, it is possible to stably form the transfer control layer having the optimum strength and pore size for printing many times. Furthermore, by adding a release agent when forming the transfer control layer, it is possible to prevent the heat-meltable ink from fusing to the porous resin and causing clogging, which reduces the print density with the number of prints. To do. At the time of peeling, the adhesion between the porous resin and the heat-fusible ink is kept low, and the entire transfer of the ink layer is prevented.

Further, according to the manufacturing method of the present invention, since the through holes can be easily formed, the initial print density does not decrease, and the pore diameter is uniform, so that there is no print unevenness. Further, according to the production method of the present invention, since the resin component for forming a porosity and the heat-melting wax component are phase-separated in a completely dissolved state, the resin component for forming a porosity or the heat-melting wax component has pores. Even if a release agent is added, it is difficult to close the pores without covering the surface of.

[0014]

Preferred Embodiments Next, preferred embodiments will be described with reference to the drawings. FIG. 1 is a sectional view showing a thermal transfer sheet of the present invention. As shown in FIG. 1, the thermal transfer sheet of the present invention has a substrate film 1, a heat-meltable ink layer 2 formed on one surface of the substrate film 1, and a transfer control layer 3 provided thereon. Is. FIG. 2 is an application example of the thermal transfer sheet of the present invention. The thermal transfer sheet of the present invention optionally contains a primer layer 4 for providing adhesiveness between the base film 1 and the heat-fusible ink layer 2, It is also possible to provide the back surface layer 5 on the other surface of the base film 1.

As the base film 1 used in the thermal transfer sheet of the present invention, the same base film as that used in the conventional thermal transfer sheet can be used as it is, and other materials can also be used. , Not particularly limited. Specific examples of the preferable substrate film 1 include, for example, polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride, polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin, chlorinated rubber, ionomer. Plastic, etc.
There are papers such as capacitor paper and paraffin paper, non-woven fabrics, and the like, and a base film that is a composite of these may be used. The thickness of the base film 1 can be appropriately changed depending on the material so that the strength and thermal conductivity thereof are appropriate, but the thickness is preferably, for example, 2 to 25.
μm.

It is also possible to provide a back layer 5 on the other surface of the base material in order to prevent the thermal head from sticking and to improve the slipperiness. The back layer 5 is formed by suitably using a binder resin to which a slip agent, a surfactant, inorganic particles, organic particles, a pigment, etc. are added.

The binder resin used for the back layer 5 is
For example, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose resin such as nitrified cotton, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal,
Examples include vinyl-based resins such as polyvinylpyrrolidone, acrylic resin, polyacrylamide, acrylonitrile-styrene copolymer, polyester resin, polyurethane resin, silicone-modified or fluorine-modified urethane resin. Among them, it is preferable to use a cross-linking resin using one having several reactive groups, for example, a hydroxyl group, and using a polyisocyanate as a cross-linking agent in combination.

The means for forming the back layer is as described above.
A material obtained by adding a slipping agent, a surfactant, inorganic particles, organic particles, a pigment, and the like to a binder resin is dissolved or dispersed in an appropriate solvent to prepare a coating liquid, and the coating liquid is coated with a gravure coater. Coating and drying are performed by conventional coating means such as a roll coater and a wire bar.

In the thermal transfer sheet of the present invention, the thickness of the heat-fusible ink layer 2 provided on one surface of the substrate film is 4 to 30 μm when dried, and preferably 5 to 15 μm. If it is 4 μm or less, sufficient printing density may not be obtained, and if it is 30 μm or more, printing sensitivity may decrease. When the adhesiveness between the base film and the heat-meltable ink layer is insufficient, the heat-meltable ink layer may be formed via the primer layer 4 as an adhesive layer. The adhesive can be formed of acrylic resin, nylon resin, vinyl chloride vinyl acetate copolymer, polyester resin, urethane resin, etc., and the thickness is 0.1 to 0.1 when dry.
About 0.2 μm is preferable.

The heat-fusible ink layer 2 comprises a conventionally known colorant and a binder, and if necessary, various mineral oils, vegetable oils, higher fatty acids such as stearic acid, plasticizers, thermoplastic resins and fillers. The one to which the additive of is added is used. Examples of the wax component used as the binder include microcrystalline wax, carnauba wax, and paraffin wax. Further, Fischer-Tropsch wax, various low molecular weight polyethylene, wood wax, beeswax, whale wax, ivowa wax, wool wax, shellac wax, candelilla wax, petrolactam, polyester wax, partially modified wax,
Various waxes such as fatty acid ester and fatty acid amide are used. Among them, those having a melting point of 50 to 85 ° C are particularly preferable. If it is 50 ° C. or lower, there is a problem in storage stability, and if it is 85 ° C. or higher, the sensitivity is insufficient. The melt viscosity at 100 ° C. is 10 to 15,000.
Waxes in the mPas range are preferred. 10 mPa
If it is s or less, bleeding etc. will occur in the print and 15,000 mP
If it is equal to or higher than as, the transfer becomes defective.

Examples of the resin component used as the binder include ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, polyethylene, polystyrene, polypropylene, polybutene, petroleum resin, vinyl chloride resin, vinyl chloride-acetic acid. Vinyl copolymer, polyvinyl alcohol, vinylidene chloride resin, methacrylic resin, polyamide, polycarbonate, fluororesin, polyvinyl formal, polyvinyl butyral, acetyl cellulose, nitrocellulose, polyvinyl acetate, polyisobutylene, ethyl cellulose or polyacetal. Particularly, those having a relatively low softening point conventionally used as a heat-sensitive adhesive, for example, a softening point of 50 to 80 ° C. are preferable.

The colorant can be appropriately selected from known organic or inorganic pigments or dyes,
For example, it has a sufficient coloring density, discolors due to light, heat, etc.
Those that do not fade are preferred. Further, it may be a substance that develops color by heating or a substance that develops color when it comes into contact with a component applied to the surface of the transfer-receiving body. Further, the color of the colorant is not limited to cyan, magenta, yellow, and black, and various colors of colorants can be used.

Further, in order to provide the heat-meltable ink layer with good heat conductivity and heat-melt transferability, a heat-conductive substance may be blended as a binder filler. Examples of such a filler include carbonaceous substances such as carbon black, and metals and metal compounds such as aluminum, copper, tin oxide, and molybdenum disulfide.

The hot-melt ink layer is formed by blending and adjusting the above-mentioned colorant component and binder component, and if necessary, solvent components such as water and organic solvent. The coating liquid is applied by a conventionally known method such as hot melt coating, hot lacquer coating, gravure coating, gravure reverse coating, or roll coating. Also, there is a method of forming using an aqueous or non-aqueous emulsion coating liquid.

The transfer control layer 3 formed on the heat-meltable ink layer contains no colorant and comprises a heat-meltable wax component composed of a resin component for forming a porosity and a polyester resin incompatible with the resin component. The resin component for forming porosity and the heat-fusible wax component are dissolved in a solvent and mixed, and a coating liquid in which the resin component and the wax component are incompatible is applied and then dried. The resin component and the heat-meltable wax component are phase-separated. After that, the heat-melting wax component is melted by heating during printing, and pores through which the heat-melting ink flows out are formed. Here, the porosity-forming resin component is insoluble in the heat-meltable ink, and has heat resistance and physical strength to the extent that structural loss does not occur at the temperature at which the heat-meltable ink flows out and is transferred. It is retained on the thermal transfer sheet side without being transferred to the surface. As a result of the transfer control layer 3 being formed on the surface of the thermal transfer sheet, the thermal meltable ink layer is suppressed from being transferred in all layers in the thickness direction, and is gradually consumed at each printing. As a result, printing can be performed many times with little change in printing density. Further, by containing the release agent, it is possible to prevent the heat-meltable ink from being fused to the resin for forming the pores and causing clogging, and the print density from decreasing with the number of prints. Further, at the time of peeling, the adhesiveness between the porous resin and the hot-melt ink is suppressed to prevent the entire transfer of the ink layer.

Examples of the porosity forming resin used in the transfer control layer 3 include cellulose esters such as cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, and cellulose butyrate, benzyl cellulose, ethyl cellulose, carboxymethyl cellulose, and the like. Cellulose ethers, cellulose derivatives such as nitrocellulose having different hydroxyl groups substituted with different groups, or vinyl acetate such as polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, etc. -Based resin, polymethylmethacrylate, ethylene-ethyl acrylate copolymer, acrylic resin such as modified silicone acrylic resin, vinyl chloride resin, chlorine-based resin such as vinylidene chloride resin, polyvinyl formal Polyvinylacetoacetal, polyvinylbutyral, etc. polyacetal resin, modified maleimide, polyethylene, polystyrene, one or a mixture of two or more resins having heat resistance such as polycarbonate is used. Of these, cellulose acetate butyrate gives good results.

The hot-melt wax component which is incompatible with the resin component used in the transfer control layer 3 is a resin which is soluble in a solvent and has a melting point of up to about 80 ° C. and is a polyester resin. Include neopentyl type polyol short chain long chain saturated dibasic acid long chain linear saturated fatty acid ester, medium chain linear saturated dibasic acid short chain linear saturated diol oligoester, polyhydroxypolyolefin oligomer long chain linear saturated fatty acid Examples thereof include esters, and one or a mixture of two or more of these resins is used. Of these,
A medium-chain linear saturated dibasic acid short-chain linear saturated diol oligoester has high solubility in a solvent such as methyl ethyl ketone and is preferably used.

As a method for forming the transfer control layer, a coating solution using a solvent capable of dissolving both the above-mentioned porous-forming resin component and the above-mentioned heat-meltable wax component is applied onto the heat-meltable ink layer. Then, a transfer control layer having a thickness of 0.2 μm to 4 μm when dried is formed. Further, if necessary, after coating, it may be heated at the melting point of the hot-melt wax or higher. When the thickness of the transfer control layer is less than 0.2 μm, the physical strength of the transfer control layer is lowered, and when the thickness is more than 4 μm, the colorant is not contained in the transfer control layer. The print density decreases.

The solvent to be used is selected depending on the combination of the resin for forming the porosity and the hot-melt wax component. Cellulose acetate butyrate is used as the resin, and the medium-chain linear saturated dibasic acid short-chain acid is used as the hot-melt wax. When chain linear saturated diol oligoesters are used, methyl ethyl ketone is preferably used.

When forming the transfer control layer, the solvent used has a high solubility, such as toluene, in order to dissolve both the resin component for forming the pores and the heat-meltable wax component. However, in the thermal transfer sheet of the present invention, the heat-meltable ink layer is provided below the transfer control layer, and when the transfer control layer is coated, toluene melts the heat-meltable ink layer and cracks. It has an adverse effect. Therefore, when forming the transfer control layer, it is preferable that the solvent to be used is not one having a high solubility in a wax such as toluene, but a solvent having a relatively low solubility such as methyl ethyl ketone is mainly used.

At this time, 50 parts by weight to 600 parts by weight of the heat-meltable wax component is added to 100 parts by weight of the resin for forming porosity.
Preferably, the transfer control layer is formed by mixing 200 parts by weight to 400 parts by weight in a solvent. If the amount of the heat-meltable wax component is less than 50 parts by weight, the pore size becomes small and the printing density decreases, which is not preferable. On the other hand, if it is more than 600 parts by weight, the pore diameter becomes large, and the strength of the porous membrane decreases, which is not preferable. According to the above method, 0.5 μm to 10 μm, more preferably 1 μm
A porous membrane having a pore size of m to 5 μm is formed.
The compounding ratio of the porous resin and the heat-melting wax, the thickness of the transfer control layer, etc. are appropriately determined depending on the printing conditions such as printing energy and printing pressure.

Further, when the transfer control layer is formed, by adding a releasing agent, the porous forming resin and the heat-meltable ink can have a releasing effect on the other. As a result, the heat-meltable ink is prevented from being fused with the porous resin to cause clogging, and the print density is prevented from decreasing with the number of prints. Further, at the time of peeling, the adhesiveness between the porous resin and the hot-melt ink is suppressed to prevent the entire transfer of the ink layer. Suitable release agents include silicone-modified acrylic resin, silicone resin, fluorine resin, fluorine-modified acrylic resin, and the like, and these are used as a mixture with a porous-forming resin.

The amount of the release agent added is 100
5 to 200 parts by weight is preferable with respect to parts by weight. When the amount of the releasing agent is less than 5 parts by weight, a good releasing action cannot be obtained at the time of printing, and the ink is likely to be completely transferred. Further, if the amount of the releasing agent is more than 200 parts by weight, the strength of the transfer control layer is lowered.

Needless to say, the multi-print thermal transfer sheet of the present invention can be applied to color printing, and the thermal transfer printer for printing the multi-print thermal transfer sheet of the present invention is not limited to a line type or a serial type.

[0035]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the text, "part" or "%" means
Unless otherwise specified, it is based on weight. (Example 1) As a base film, a heat-fusible ink layer coating solution having the following composition was applied to one surface of a 4.5 μm-thick polyethylene terephthalate film that had been subjected to heat treatment, and dried to obtain a thick film. A heat-meltable ink layer having a thickness of 10 μm is formed, a transfer control layer coating solution having the following composition is applied onto the layer, and dried to form a transfer control layer having a thickness of 0.3 μm. Prepare a thermal transfer sheet for reprinting. The pore size of the transfer control layer is 1.5 μm to 2.5 μm. Hot-melt ink layer coating solution Carbon black (Mitsubishi Chemical Co., Ltd. Diablack) 20 parts Carnauba wax 10 parts Paraffin wax 60 parts Ethylene-vinyl acetate copolymer 10 parts transcriptional control layer coating liquid cellulose acetate butyrate 10 parts Medium chain linear saturated dibasic acid Short chain linear saturated diol oligoester 25 parts (ZN manufactured by Nisshin Fine Chemical Co., Ltd.) Silicone modified acrylic resin (20% methyl ethyl ketone solution) 5 parts Methyl ethyl ketone 250 parts

(Example 2) A thermal transfer sheet for multiple printing according to the present invention is prepared in the same manner as in Example 1 except that the coating solution for the transfer control layer has the following composition. The pore size of the transfer control layer is
It is 0.5 μm to 2 μm. Transfer Control Layer Coating Solution Cellulose Acetate Butyrate 10 parts Medium-chain linear saturated dibasic acid short-chain linear saturated diol oligoester 25 parts (SAH manufactured by Nisshin Fine Chemical Co., Ltd.) Silicon modified acrylic resin (20% methyl ethyl ketone solution) 5 Part Toluene 50 parts Methyl ethyl ketone 200 parts

(Comparative Example 1) A thermal transfer sheet for multiple printing of the present invention is prepared in the same manner as in Example 1 except that the coating solution for the transfer control layer has the following composition. Transfer control layer coating liquid Cellulose acetate butyrate 10 parts Particulate carnauba wax with an average particle size of 2.2 μm 80 parts (25% methyl ethyl ketone dispersion) Toluene 100 parts Methyl ethyl ketone 140 parts

Comparative Example 2 A thermal transfer sheet for multi-printing of the present invention is prepared in the same manner as in Example 1 except that the coating composition for the transfer control layer has the following composition. Transfer control layer coating liquid Cellulose acetate butyrate 10 parts Particulate carnauba wax with an average particle size of 2.2 μm 20 parts (25% methyl ethyl ketone dispersion) Silicon modified acrylic resin (20% toluene solution) 25 parts Toluene 100 parts Methyl ethyl ketone 180 parts

Using the thermal transfer sheets of Examples and Comparative Examples described above, printing was carried out under the following conditions to measure the print density, and the results shown in Table 1 were obtained. Printing conditions Equipment: Line thin film head type Printing energy: 23 mj / mm ² Image receiving paper; Fine paper (Beck smoothness 400 seconds) Printing density Measured with a Macbeth reflection densitometer.

[0040]

[Table 1]

[0041]

As described above, according to the present invention, when the transfer control layer forming coating liquid is applied, the resin component and the wax component are in a good compatible state and the coating amount can be easily adjusted. Can be secured. After coating, the solvent evaporates during drying and the thermal transfer sheet is formed with the resin component and the wax component phase-separated. Furthermore, the heating during printing melts the wax component and forms pores that control the outflow amount of the hot-melt ink. Here, the size of the pores can be controlled by adjusting the mixing ratio of the porosity forming resin component and the wax component. Therefore, by carrying out this adjustment, it is possible to stably form the transfer control layer having the optimum strength and pore size for printing many times. Further, according to the manufacturing method of the present invention, since the through holes can be easily formed, the initial print density does not decrease, and the pore size is uniform, so that there is no print unevenness.

[0042]

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a thermal transfer sheet of the present invention.

FIG. 2 is a cross-sectional view showing an application example of the thermal transfer sheet of the present invention.

[Explanation of symbols]

 1 Base Film 2 Heat Melt Ink Layer 3 Transfer Control Layer 4 Primer Layer 5 Back Layer

Claims (4)

[Claims] 1. A thermal transfer sheet for multi-use printing comprising a base film, a heat-fusible ink layer, and a transfer control layer laminated in this order, wherein the transfer control layer does not contain a colorant and is porous. Resin component for heat treatment and a heat-meltable wax component consisting of a polyester resin incompatible with the resin component, wherein the resin component for forming a pore and the heat-meltable wax component are phase-separated. Thermal transfer sheet for printing. 2. The transfer control layer contains a medium-chain linear saturated dibasic acid short-chain linear saturated diol oligoester as a heat-melting wax component, as described above.
The thermal transfer sheet for multi-time printing described in. 3. The thermal transfer sheet for multiple printing according to claim 1, wherein the transfer control layer contains a release agent. 4. A method for producing a thermal transfer sheet for multi-time printing, comprising a base film, a heat-fusible ink layer, and a transfer control layer laminated in this order, wherein the transfer control layer does not contain a colorant. The resin component for forming a porosity and the heat-melting wax component consisting of a polyester resin incompatible with the resin component, the resin component for forming a porosity and the heat-melting wax component are dissolved in a solvent and mixed, A coating liquid in which the resin component and the wax component are incompatible is applied onto the heat-meltable ink layer and then dried, whereby phase separation of the resin component for forming a pore and the heat-meltable wax component is performed. A method for producing a thermal transfer sheet for multi-use printing, which comprises forming a transfer control layer using