JP2000094843A - Thermal transfer sheet, integrated thermal transfer sheet and recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a thermal transfer sheet and an integrated thermal transfer sheet for recording a plurality of colors (multicolor) on a body to be transferred by using a thermal printer to be used combinedly with heat-sensitive papers heretofore available and provided with the printing quality, sharpness and printing record sensitivity and provide a recording method thereof. SOLUTION: A thermal transfer sheet 1 is provided with a thermal transfer ink layer on one face of a base film 4, and the thermal transfer ink layer is formed of two layers or more, and hues of respective layers are different, and all layers of different hues of the thermal transfer ink layer are transferred at the time of low energy, while only an outermost layer 6 is substantially transferred at the time of high energy. Namely when the low energy is applied on the thermal transfer sheet 1, the sheet is released on the interface between the base film 4 and the thermal transfer ink layer 5, and all the layers 5 and 6 of different hues of the thermal transfer ink layer are transferred on a body to be transferred, while when high energy is applied on the thermal transfer sheet 1, the sheet is released on the interface between the respective ink layers of the thermal transfer ink layer formed of two layers or more, and only the outermost layer 6 is transferred on the body to be transferred.

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 thermal transfer ink layer formed on a base film, and more particularly, to an integrated thermal transfer sheet in which a thermal transfer sheet and a transfer object are temporarily bonded, and more particularly, to an A3 size or larger. One type of thermal transfer sheet that is effective for large printers capable of recording
The present invention relates to a thermal transfer sheet capable of reproducing hues of more than colors and a recording method thereof.

[0002]

2. Description of the Related Art In recent years, a thermal transfer medium utilizing a thermal fusion transfer method has been used for output printing of a computer, a processor, or the like. In general, a thermal transfer sheet using a thermal fusion transfer method uses a plastic film such as polyester or cellophane having a thickness of about 3 to 20 μm as a base material, and mixes a vehicle (mainly wax) with a coloring agent such as a pigment or a dye. The thermal transfer ink layer made of the heat-meltable ink is formed by coating. When printing on an object to be transferred using these thermal transfer sheets, the thermal transfer sheet is supplied from a roll around which the thermal transfer sheet is wound, and on the other hand, a continuous or single-sheet object is supplied, and both are stacked on a platen. In this state, the thermal transfer sheet is heated from the back side by a thermal head, and the ink layer is thermally melt-transferred to form a desired image on the transfer-receiving body.

However, even if these thermal transfer sheets are diverted to, for example, a thermal printer using thermosensitive coloring paper, the above thermal printer employs a configuration in which the recording paper itself develops thermal coloring. In the state of the printer as it is without the transfer device of
Diversion of the thermal transfer sheet was not possible. In order to solve this problem, the thermal transfer sheet, which is provided with a thermal transfer ink layer made of hot-melt ink on the substrate, can be temporarily bonded and peeled to the transfer object made of plain paper, synthetic paper, coated paper, etc. Has already been proposed.
In the integrated thermal transfer sheet, an image is formed on the transferred body by separating the transferred body from the thermal transfer sheet after printing.

[0004]

A number of attempts have been made to realize recording of a plurality of colors (multicolors) with one kind of the above-described thermal transfer sheet. For example, 4-4
In Japanese Patent No. 1052, a high-temperature transfer layer is provided on a substrate, a low-temperature transfer layer containing a leuco dye is provided thereon, and a color developer is provided on the receiving sheet side. In addition, 3-25355
In Japanese Patent Application Laid-Open Publication No. H11-264, there is proposed a thermal transfer sheet in which an ink layer that similarly transfers at a high temperature and a thermal paper that develops a color at a low temperature are removably integrated. Neither of them can record multiple colors on general-purpose plain paper. Further, many patents in which a high-temperature transfer layer and a low-temperature transfer layer are sequentially provided on a substrate have been proposed. In any case, the outermost layer is transferred when a low temperature is applied,
Since a plurality of colors are transferred in a mixed color when a high temperature is applied, there is a problem that a dark hue occurs when a high temperature is applied.

In Japanese Patent Publication No. 6-65516,
With respect to a recording medium and a recording method for transferring a two-color recording image, a proposal has been made to vary the hue by controlling the peeling time and the peeling distance, but this is applied to an integrated thermal transfer sheet to control the hue. It is impossible to do. Therefore, the present invention solves the above-mentioned problems, and enables recording of a plurality of colors (multicolors) on an object to be transferred by using a thermal transfer printer that can be shared with a conventional thermal paper. It is an object of the present invention to provide a thermal transfer sheet and an integrated thermal transfer sheet having excellent print recording sensitivity and a recording method thereof.

[0006]

Means for Solving the Problems In order to achieve the above object, the present invention relates to a thermal transfer sheet having a thermal transfer ink layer formed on one surface of a base film, wherein the thermal transfer ink layer comprises two or more thermal transfer ink layers. And the hue of each layer is different,
Further, at the time of low energy, all the layers having different hues of the thermal transfer ink layer are transferred, and at the time of high energy, substantially only the outermost layer is transferred. Preferably, the outermost layer of the thermal transfer ink layer has a bright hue, and the bright color is transferred at high energy. In the present invention, the bright color means a hue having high lightness among chromatic colors. Further, an integrated thermal transfer sheet of the present invention is characterized in that the thermal transfer sheet described above and a transfer receiving body are temporarily bonded and releasably bonded. Further, it is preferable that a temporary adhesive layer is provided between the thermal transfer ink layer and the transfer object.

It is preferable that the thermal transfer ink layer on the transfer object side contains an adhesive component. Further, the recording method of the present invention is characterized in that a plurality of colors are recorded on an object to be transferred by using the above-mentioned thermal transfer sheet or the integrated thermal transfer sheet and changing the energy applied from a thermal head. Further, a recording method of the present invention is characterized in that the thermal transfer sheet described above or the integrated thermal transfer sheet is used to record a plurality of colors on a transfer object by a single scan from a thermal head.

The thermal transfer sheet of the present invention has a thermal transfer ink layer formed on one surface of a substrate film, the thermal transfer ink layer is composed of two or more layers, each layer has a different hue, and the thermal transfer All layers having different hues of the ink layer are transferred, and at the time of high energy, substantially only the outermost layer is transferred. That is, when low energy is applied to the thermal transfer sheet, the thermal transfer sheet is peeled off at the interface between the substrate film and the thermal transfer ink layer, and all the layers of the thermal transfer ink layer having different hues are transferred to the transfer target. When high energy is applied to the thermal transfer sheet, the thermal transfer sheet peels off at the interface between the ink layers of the thermal transfer ink layer composed of two or more layers (at the interface between the outermost layer and the layer adjacent to the outermost layer), and Only is transferred to the transfer object. Therefore, by changing the applied energy, it is possible to record a plurality of colors (multicolors) on the transfer object.

[0009]

Next, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, for example, the thermal transfer sheet 1 of the present invention has thermal transfer ink layers 5 and 6 formed on one surface of a base film 4, and the thermal transfer ink layers are composed of two layers, and each layer has a different hue. Further, when the energy is low, the entire two layers are transferred, and when the energy is high, only the outermost layer 6 is transferred. As shown in FIG. 2, the thermal transfer sheet 1 of the present invention can also form three thermal transfer ink layers of thermal transfer ink layers 5, 7, and 6 on one surface of a base film 4. The hues are different, the entire three layers are transferred at low energy, only the outermost layer 6 is transferred at high energy, and at intermediate energy,
Two layers of the thermal transfer ink layers 6 and 7 are transferred. FIG.
As shown in FIG. 1, in the present invention, the integrated thermal transfer sheet 2 is configured as a so-called integrated thermal transfer sheet 2 in which the thermal transfer sheet 1 and the transferred object 3 are bonded in a releasable manner.
It is possible to take a product form in which the transfer target 3 and the thermal transfer sheet 1 are co-wound.

As shown in FIGS. 2 and 5, the thermal transfer sheet 1 and the integrated thermal transfer sheet 2 of the present invention prevent the thermal head 12 from sticking to the other surface of the base film 4 if necessary. In addition, the back layer 8 that improves the slipperiness can be formed. As shown in FIG. 3, the integrated thermal transfer sheet 2 of the present invention comprises a thermal transfer ink layer 6 and a transfer target 3.
And a temporary adhesive layer 11 can be provided between them to bond them. Then, as shown in FIGS. 4 and 5, the receiving member 3 can be formed on the substrate 3 in order to improve the transferability and the fixability of the thermal transfer ink layer on the base material 9. still,
The integrated thermal transfer sheet 2 is conveyed as shown by the arrow in the figure,
By peeling off the transferred body 3 by changing the applied energy by the thermal head 12, a multicolor image of two or more colors can be formed on the transferred body 3. Hereinafter, these configurations will be described in detail.

(Substrate film) As the substrate film 4 used in the thermal transfer sheet of the present invention, the same substrate as that used in the conventional thermal transfer sheet can be used as it is, and other substrates can be used. And is not particularly limited. Specific examples of preferred base film include, for example, polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride, polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol,
Plastics such as fluororesins, chlorinated rubbers, and ionomers; papers such as condenser paper and paraffin paper; non-woven fabrics; The thickness of the substrate film can be appropriately changed depending on the material so that the strength and the thermal conductivity are appropriate, but the thickness is preferably, for example, 2 to 25 μm.

(Thermal Transfer Ink Layer) The thermal transfer ink layer formed on the base film is composed of two or more layers, that is, a plurality of layers, each layer having a different hue, and the hue of the thermal transfer ink layer at low energy. All different layers transfer,
At the time of high energy, substantially only the outermost layer is transferred. Each thermal transfer ink layer is mainly composed of a binder and a colorant, and the colorant can be appropriately selected from conventionally known dyes and pigments. For example, known black pigments such as carbon black, black pigments such as graphite, red pigments such as red iron oxide, antimony red, yellow pigments such as ocher, zinc yellow, blue pigments such as dark blue, ultramarine blue, titanium oxide, and zinc pigments such as zinc sulfide. Inorganic pigments can be used. In addition, benzimidazolone-based monoazo, quinacridone-based, phthalocyanine-based, sulene-based, dioxazine-based, isoindolinone-based, perylene-based, thioindigo-based, pyrocholine-based, fluorpine-based, and quinophthalone-based organic pigments are also included.
When used for outdoor applications such as posters and guide boards, the above-mentioned inorganic or organic pigments have excellent weather resistance without fading.

The thermal transfer sheet of the present invention comprises a plurality of thermal transfer ink layers, each layer having a different hue, and the outermost layer of the thermal transfer ink layer preferably has a bright hue, and the bright color is transferred at high energy. You. Then, it is desirable that the hue of the thermal transfer ink layer be dark under the outermost layer toward the base film. For example, as shown in FIG. 3, only one thermal transfer ink layer is transferred (thermal transfer ink layer 6), and as shown in FIG. 4, every two thermal transfer ink layers (thermal transfer ink layer 6 and thermal transfer ink layer 6) are transferred. As shown in FIG. 5, when the thermal transfer ink layer is transferred every three layers (the thermal transfer ink layer 5, the thermal transfer ink layer 7, and the thermal transfer ink layer 6), as shown in FIG. The hue of the lower layer (the thermal transfer ink layer 6 or the thermal transfer ink layer 7) of the transferred thermal transfer ink layer may make the hue of the upper layer (the thermal transfer ink layer 5 or the thermal transfer ink layer 7) turbid when the layers or every three layers are transferred. Because it has no adverse effect. For the thermal transfer ink layer composed of a plurality of layers, it is preferable in practice that the color of the thermal transfer ink layer on the substrate film side be black. The configuration of the thermal transfer ink layer can be selected from two layers, three layers or more, or two or more layers.

In the integrated thermal transfer sheet of the present invention, an opaque layer using a highly opaque white pigment such as titanium oxide or metal powder may be provided between the thermal transfer ink layers composed of a plurality of layers. Further, the above-mentioned concealing layer can be used for a surface layer remote from the substrate film side, or a heat transfer ink layer having high concealing property using brass or aluminum powder as a coloring agent can be provided on the substrate film side. The amount of the coloring agent used is preferably about 5 to 70% by weight based on the solid content of the thermal transfer ink layer.

As the binder contained in the thermal transfer ink layer, a wax is used as a main component, and a mixture of the wax and a drying oil, a resin, a mineral oil, a derivative of cellulose or rubber, or the like is used. Examples of the wax used include microcrystalline wax, carnauba wax, and paraffin wax. Furthermore, Fischer-Tropsch wax, various low molecular weight polyethylenes, wood wax, beeswax, whale wax, Ibota wax, wool wax, shellac wax, candelilla wax, petrolactam,
Various waxes such as polyester wax, partially modified wax, fatty acid ester, fatty acid amide, sterol wax, sugar cane wax, rice wax and the like can be mentioned. In the present invention, the wax can be mixed with a thermoplastic resin having a relatively low softening point to improve the adhesiveness of the ink to the thermal transfer image receiving paper.

The thermal transfer ink layer has a rubber elasticity as an adhesive component for the purpose of improving the film strength of the ink layer, imparting adhesiveness, or increasing the cohesive force of the ink layer. It is preferable to contain a thermoplastic elastomer having the following. In particular, in the thermal transfer sheet of the present invention, it is preferable that the thermoplastic elastomer is contained in the thermal transfer ink layer 5 in contact with the base film, and when low energy is applied, the thermal transfer ink layer 5 easily peels off at the interface between the base film and the thermal transfer ink layer. When high energy is applied, at the interface between the ink layers of the thermal transfer ink layer composed of two or more layers (at the interface between the outermost layer and the layer adjacent to the outermost layer)
Peel off, so that only the outermost layer is transferred to the transfer target,
The adhesion at the interface between the substrate film and the thermal transfer ink layer is increased, and the thermal transfer ink layer on the substrate film side does not transfer to the transfer object and remains on the substrate film side. In other words,
When high energy is applied, the thermal transfer ink layer on the base film side reversely transfers to the base film side. As described above, by changing the applied energy, it is possible to record a plurality of colors (multicolors) on the transfer target.

As described above, the thermal transfer ink layer 5 in contact with the base film is not limited to containing the thermoplastic elastomer, but is easily peeled off from the base film when low energy is applied, and when high energy is applied. A binder or an additive capable of adjusting the adhesive force with the base film by changing the temperature so that the adhesion to the base film is increased and the reverse transfer to the base film side is performed. Can be used for For example, the shell of the microcapsule is not broken by low-temperature printing, but is broken by high-temperature printing, so that the core contains a component having a relatively low glass transition temperature Tg. Will be possible.

Examples of the thermoplastic elastomer having rubber elasticity include ethylene-vinyl acetate copolymer, butadiene rubber, styrene-butadiene rubber, nitrile rubber, nitrile-butadiene rubber, high styrene rubber, isoprene rubber, and acrylic rubber. And the like, synthetic rubber, natural rubber and the like. Among the above thermoplastic elastomers, it is particularly preferable to use an ethylene-vinyl acetate copolymer, a styrene-butadiene rubber, and an acrylonitrile-butadiene rubber in that the printability becomes good. Such a thermoplastic elastomer basically exhibits its effect if it is contained in an amount of 1 to 50% by weight in terms of the solid content of the thermal transfer ink layer, but a good result is obtained particularly when the content is 5 to 40% by weight. Show. If the content of the thermoplastic elastomer is small, a problem arises in that a sufficient cohesive force cannot be obtained in the thermal transfer ink layer, and printing defects easily occur. On the other hand, if the content of the thermoplastic elastomer is too large, the film strength of the thermal transfer ink layer is increased, which causes a disadvantage that the resolution at the time of printing is reduced.

Such a thermoplastic elastomer having rubber elasticity has a tensile strength (JIS K6301) of 1 k.
Those having a g / cm ² or more and less than 100 kg / cm ² are preferable. May become the value of the tensile strength is less than 1 kg / cm ^2, when or a 100 kg / cm ² or more, disadvantageously lowering the printing quality. Further, the glass transition temperature Tg of the thermoplastic elastomer having rubber elasticity that can be used in the thermal transfer ink layer 5 is preferably in the range of 0 ° C to 60 ° C. When a material having a Tg of less than 0 ° C. is used,
The adhesion between the substrate film and the thermal transfer ink layer becomes too high, and it becomes difficult to separate the substrate film and the thermal transfer ink layer after printing. On the other hand, if the Tg exceeds 60 ° C., the film strength becomes weak, and for example, in a non-printed portion in a temporarily bonded state, a so-called background stain such as a heat transfer ink layer being taken on an image receiving paper for heat transfer is generated. Occurs.

When the thermal transfer ink layer 5 in contact with the substrate film of the present invention is formed of an emulsion ink in which a colorant and an aqueous dispersion of a thermoplastic elastomer are mixed, the thermal transfer ink layer 6 located at the outermost layer of the thermal transfer sheet is It is preferable to form by hot-melt coating with a binder mainly composed of wax, or by dissolving or dispersing the material constituting the ink layer in an organic solvent, and coating and forming. Specifically, the thermal transfer ink layer 6 contains wax as a main component so that printing can be performed under low energy, and the melting point of the wax is 50 ° C. to 85 ° C. in consideration of storability and transferability at low energy. Those in the range are preferred. The component ratio is wax / binder resin = 100/0.
It is preferably set to 70/30.

As shown in FIGS. 4 and 5, the thermal transfer ink layer 6 and the transfer medium 3 are mixed with a suitable amount of the above-mentioned adhesive component of the thermoplastic resin having a relatively low softening point. Can be directly releasably attached to the transfer target body 3 without providing a temporary adhesive layer between them. To form a thermal transfer ink layer on the base film, the above-mentioned binder mainly composed of wax, together with other necessary components,
A melt is prepared by melt-kneading, which is performed by a general method using hot melt coating, or, as another method, a wax-based binder in an aqueous medium which may contain alcohol or the like. Emulsions emulsified or dispersed in the emulsion ink obtained by mixing an aqueous dispersion of a colorant and a thermoplastic elastomer, gravure printing, screen printing, by a forming means such as a reverse or direct roll coating method using a gravure plate, Coating, drying and forming. Further, the material constituting the thermal transfer ink layer can be formed by dissolving or dispersing the material in an organic solvent, and applying the solution. In the present invention, the above forming means is repeated a plurality of times,
Layers having different hues are laminated a plurality of times. The thermal transfer ink layer thus formed usually has a thickness of about 0.3 to 10 μm as a single layer in a dry state and about 1 to 20 μm as a whole of a plurality of thermal transfer ink layers.

(Release Layer) In the present invention, a release layer may be provided between a plurality of thermal transfer ink layers or between a substrate film and a thermal transfer ink layer. For example, in a thermal transfer sheet, a release layer is provided on a substrate film, and when two or more thermal transfer ink layers are formed on the release layer, all layers of the thermal transfer ink layer are transferred with low energy,
At high energy, the thermal transfer ink layer 5 including the release layer is substantially reverse-transferred to the base film side by the action of the thermal transfer ink layer 5.

Materials used for the release layer include waxes, thermoplastic resins, a mixture thereof, and, if necessary, additives such as organic and inorganic fillers.
Examples of the wax used for the release layer include microcrystalline wax, carnauba wax, and paraffin wax. Furthermore, Fischer-Tropsch wax, various low molecular weight polyethylene, wood wax, beeswax,
Examples include various waxes such as whale wax, wax wax, wool wax, shellac wax, candelilla wax, petrolactam, polyester wax, partially modified wax, fatty acid ester, and fatty acid amide. Among them, those having a melting point of 50 to 85 ° C are particularly preferable. If the temperature is lower than 50 ° C., there is a problem in storage stability, and if the temperature is higher than 85 ° C., the sensitivity of printing becomes insufficient.

Specific examples of the thermoplastic resin used for the release layer include cellulose resin, melamine resin, polyester resin, polyamide resin, polyolefin resin, acrylic resin, styrene resin, and ethylene-vinyl acetate. Examples include a thermoplastic resin such as a polymer and styrene-butadiene rubber. In particular, 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. In the case where more than two layers are provided, it is preferable that the melting point or softening point of the binder decreases in order from the release layer on the base film side to the release layer on the transfer object side. The release layer is formed by applying a coating liquid for forming a release layer in a dry state by a conventionally known method such as hot melt coating, hot lacquer coating, gravure direct coating, gravure reverse coating, knife coating, air coating, or roll coating. Effort 0.1-3.0
g / m ² is desirable. If the coating amount of the release layer is less than 0.1 g / m ² , sufficient releasability cannot be obtained at the time of printing, while if it exceeds 3.0 g / m ² , the thermal energy of printing is excessively consumed. Therefore, sufficient heat is not applied to the thermal transfer ink layer.

(Back Layer) It is also possible to provide a back layer 8 on the other surface of the base film in order to prevent sticking of the thermal head and improve slipperiness. The back layer is formed by suitably using a binder resin to which a slip agent, a surfactant, inorganic particles, organic particles, a pigment, and the like are added. Binder resin used for the back layer, 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 , Polyvinylpyrrolidone, acrylic resin, polyacrylamide, acrylonitrile-vinyl copolymer such as styrene copolymer, polyester resin, polyurethane resin,
Silicone-modified or fluorine-modified urethane resins, melamine resins, urea resins, and the like can be given.

Among these, those having several reactive groups, for example, those having a hydroxyl group, are used.
It is preferable to use a crosslinked resin in combination with a polyisocyanate or the like. The means for forming the back layer may be formed by dissolving or dispersing a material obtained by adding a slipping agent, a surfactant, inorganic particles, organic particles, a pigment, etc. to a binder resin in an appropriate solvent, as described above, Is prepared, and the coating liquid is applied by a conventional coating means such as a gravure coater, a roll coater, and a wire bar, and dried. The thickness of the back layer is usually 0.01 to 10 in a dry state.
It is about μm.

Next, the transfer member 3 integrated with the thermal transfer sheet 1 will be described. Transfer object 3 used in the present invention
May be composed of the base material 9 alone, or may be formed by forming the receiving layer 10 on the base material 9. (Substrate) The material of the substrate 9 is not particularly limited, and is, for example, a synthetic paper such as polyolefin or polystyrene; plain paper, high-quality paper, PPC paper, art paper, lightweight coated paper,
Coated paper, cast coated paper, lightly coated paper, wallpaper, backing paper, synthetic resin or emulsion impregnated paper, synthetic rubber latex impregnated paper, synthetic resin internal paper, paperboard, etc .; polyester, polyvinyl chloride, polychlorinated paper Vinylidene, polyurethane, polyvinyl alcohol, polypropylene, polyethylene, polystyrene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, methylpentene polymer, polyimide, polyamide, fluorine resin, etc. A transparent or opaque plastic material is used.

A white opaque film or a foamed sheet formed by adding a white pigment or a filler to these plastic materials can also be used, and is not particularly limited. Further, a transparent plastic film used for an OHP (overhead projector) may be used as the base material of the transfer object. In general, synthetic papers include Yupo (Oji Yuka), Peachcoat (Nisshinbo), Tuffa (Tatsuno Chemical), Eleven (Tokai Pulp), Tyvek (DUPONT), Crispar, Toyopearl (Toyobo), etc. There is. Further, the base material may be a laminate made of any combination of the above materials. In this case, a laminate of cellulose fiber paper and synthetic paper or a laminate of cellulose fiber paper and plastic film is typically given.

(Receiving layer) On the above-mentioned base material, the receiving layer 10 was used in order to improve the transferability and fixability of the thermal transfer ink layer.
Can be formed. The receiving layer is a layer for receiving the ink transferred from the thermal transfer ink layer.
The resin binder forming the receiving layer is a resin having excellent ink fixing properties, for example, ethylene-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer, acrylonitrile-butadiene rubber, and acrylic copolymer such as styrene-acryl. Coalesce, polyester, polyvinyl alcohol, polyurethane, styrene-butadiene rubber, acrylic resin, naturally processed resin, petroleum resin, and the like. Further, wax such as carnauba wax and paraffin wax may be used.

The receiving layer preferably contains a filler in the above resin. At this time, to form the receiving layer, a filler (filling amount) for pulp paper, for example, kaolin, calcium carbonate, satin white, titanium dioxide,
White pigments such as aluminum hydroxide, SBR, NBR,
The coating is performed by coating and drying a latex containing a binder such as starch or a coating solution dispersed in a binder solution on the surface of a paper substrate. Use of a coating liquid in which a filler for pulp paper is dispersed in a latex containing an SBR binder, in particular, results in better thermal transfer printing quality. The solid content ratio between the filler and the binder used is important, and the amount of the binder used is preferably in the range of 1 to 100 parts by weight per 100 parts by weight of the filler. By setting the content within this range, the transfer quality of the thermal transfer print becomes good.
If the amount of the binder is less than 1 part by weight per 100 parts by weight of the filler, the amount of the binder used is too small,
The receiving layer breaks and peels, causing a problem of powder dropping. on the other hand,
The amount of the binder used is 10 per 100 parts by weight of the filler.
If it exceeds 0 parts by weight, the amount of the binder used is too large,
During storage of the integrated thermal transfer sheet, a so-called background stain occurs in which the thermal transfer ink layer is transferred to the transfer receiving body in the non-printed portion. In addition, it is natural that the above-mentioned coating liquid may further contain additives known in the paper coating technology.

The preferable coating amount of the receiving layer is about 0.5 to 30 g / m ² in terms of solid content. 0.5 coating amount
When it is less than g / m ² , the fixability of the thermal transfer ink layer is deteriorated depending on the surface properties of the substrate. On the other hand, the coating amount is 3
When it exceeds 0 g / m ² , the film strength of the receiving layer becomes weak, and the receiving layer is easily formed on the side of the thermal transfer sheet when peeling off with the integrated thermal transfer sheet. After the coating of the receiving layer, the surface smoothness can be increased by performing a calendering treatment for the purpose of improving printability. In order to improve the printability, the smoothness of the receiving layer is important.
It is particularly preferable to set the range to 000 sec. However, it is a condition measured by a Beck smoothness tester manufactured by Toyo Seiki. If the Beck smoothness is less than 100 sec, the surface is rough, so that voids are likely to occur in the solid portion in the transfer quality of the thermal transfer printed matter, while if the Beck smoothness exceeds 10,000 sec, the smoothness is high. , The adhesive strength is increased, and the soil is easily generated.

Means for forming the receptor layer include a gravure printing method, a screen printing method, and a coating liquid in which a resin or wax and a filler are dissolved or dispersed in an appropriate solvent.
It is formed by applying and drying by forming means such as a roll coating method and an air knife method. In order to improve the adhesion between the receiving layer and the substrate, it is also preferable to form the receiving layer on the substrate via a primer layer. Acrylic resin, nylon resin, vinyl chloride-vinyl acetate copolymer,
Using a polyester resin, urethane resin or the like, a gravure coat, a gravure reverse coat, a roll coat, a knife coat, etc., in a dry state, having a thickness of 0.1 to 5 μm
Is formed. Further, the film strength of the primer layer can be improved by performing a curing agent or self-crosslinking.

(Temporary adhesive layer)
With the thermal transfer sheet, the recording surface side of the object to be transferred and the thermal transfer ink layer side are releasably attached and integrated. At this time, a temporary adhesive layer 11 is provided between the thermal transfer ink layer and the transfer-receiving body, integrated, and does not peel off during printer processing or other handling. It is preferable to do so. The temporary adhesive layer may use any conventionally known adhesive, but is preferably a tacky resin and wax having a low glass transition temperature, or a thermoplastic film which maintains a particle shape at room temperature but is heated to form a film. It is preferable to use one composed of fine particles and wax. An acrylic resin is generally used as the adhesive resin having a low glass transition temperature. In addition, as the thermoplastic fine particles, ethylene-vinyl acetate copolymer particles, ionomer particles, polyethylene resin particles, and the like are used.

The adhesive strength (g) of such a temporary adhesive layer is 2
When a sample of 5 mm (width) x 55 mm (length) was cut out and measured with a surface friction meter (HEIDEN-17, manufactured by Shinto Kagaku) at a pulling speed of 1,800 mm / min, 300 to 2 A range of 2,000 g is preferred. If the adhesive strength is less than the above range, the adhesive strength between the thermal transfer sheet and the transfer-receiving body is too low, so that the two easily peel off, and the thermal transfer sheet easily wrinkles in the width direction during printing. If the adhesive force exceeds the above range, the adhesive force is sufficient, but the thermal transfer ink layer is easily transferred to the transfer target even in the non-printed area, and the background smear of the transfer target occurs. Cheap. On the other hand, if the adhesive strength is too high, it is difficult to remove the thermal transfer sheet after printing.

The above adhesive resin used for such a temporary adhesive layer has a glass transition temperature of -90 ° C to -10 ° C.
Are preferred. Specifically, there are a rubber-based adhesive resin, an acrylic-based adhesive resin, a silicone-based adhesive resin, and the like. Examples of the form include a solvent solution type, an aqueous solution type, a hot melt type, an aqueous or oily emulsion type, and the like. Any of them can be used. Further, while maintaining the particle shape at room temperature, as the thermoplastic fine particles to form a film under heating, polyethylene resin, ionomer resin, ethylene-vinyl acetate copolymer resin and the like, and the minimum film forming temperature is 40 to 150 C. is preferred. When such an adhesive resin is used alone,
Excellent adhesiveness is obtained, but the transferability of the transferred object is insufficient and uneven, and if a sudden force is applied before thermal transfer, such as during manufacturing, storage, or transportation, thermal transfer of the thermal transfer sheet There is a problem in that the ink layer is transferred to the transfer-receiving body side, causing background stains. Further, at the time of thermal transfer, the thermal transfer ink layer has poor foil-cutting properties. For example, the thermal transfer ink layer transfers to the periphery of a region to which heat is applied by a thermal head, and the resolution of a transferred image is poor.

These problems can be solved by adding the wax emulsion used in the formation of the thermal transfer ink layer to the above emulsion tacky resin so that the adhesiveness can be adjusted to a preferable range, and Is solved, and the resolution of the transferred image is improved. The weight ratio of the above-mentioned adhesive resin and wax is preferably 1: 0.2-10. Outside of this range, various problems as described above are likely to occur, which is not preferable. The temporary adhesive layer composed of the above components may be provided on the surface of the transfer-receiving body side.However, in order to maintain the adhesiveness of the printed matter, the temporary adhesive layer may be provided on the surface of the thermal transfer ink layer on the thermal transfer sheet side. preferable. In this case, since the adhesive resin of the temporary adhesive layer is used as an aqueous emulsion, the thermal transfer ink layer is not damaged. The method of applying and drying the emulsion is not particularly limited, and various known methods can be selected.

The above-mentioned temporary adhesive layer has a thickness of 0.1 to 1
0 μm range (0.05 to 5 g / m
² ) is preferable. Adhesion between the thermal transfer sheet and the transfer-receiving member is preferably performed by continuously forming a temporary adhesive layer on the surface of the thermal transfer ink layer of the thermal transfer sheet and utilizing the adhesiveness imparted to the temporary adhesive layer. This is done by bonding the body and winding it into a roll. At the time of winding, the object to be transferred may be set outside or the thermal transfer sheet may be set outside.

(Recording Method) A recording method using the above-described thermal transfer sheet will be described below. By variably applying the energy applied from the thermal head to the back side of the thermal transfer sheet (the side opposite to the side on which the thermal transfer ink layer is provided), a plurality of colors can be recorded on the transfer-receiving body. Specifically, for example, the thermal head is 300 dpi.
, A low level of 0.1-0.6 mj / dot;
When a high level of two kinds of energy of 0.6 to 1.2 mj / dot is applied, two or more thermal transfer ink layers on the base film are transferred at a low level of energy, and substantially at a high level of energy. Only the outermost layer is transferred. In other words, when low energy is applied to the thermal transfer sheet, the thermal transfer ink layer is peeled off at the interface between the substrate film and the thermal transfer ink layer, and two or more thermal transfer ink layers are transferred to the transfer target,
When high energy is applied to the thermal transfer sheet, the thermal transfer ink layer composed of two or more layers peels off at the interface between the ink layers (at the interface between the outermost layer and the layer adjacent to the outermost layer), leaving only the outermost layer. It is transcribed on the transfer target.

Also, using the above-mentioned integrated thermal transfer sheet,
When changing the applied energy, it is preferable to record a plurality of colors on the transfer target body by one scan from the thermal head. This is because wrinkles and breaks are less likely to occur when printing is performed in a single scan from the thermal head by varying the energy applied from the thermal head than when the thermal head is scanned multiple times. Further, printing can be performed in a short time in one scan, which is efficient.

[0040]

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 <Preparation of Thermal Transfer Sheet> A 4.5 μm-thick polyethylene terephthalate film having a back surface layer provided on the back surface was used as a base film, and an ink layer composition 1 having the following composition was provided on the surface opposite to the back surface layer. Is applied so as to have a solid content of 2.0 g / m ^2, and an ink layer composition 2 having the following composition is coated on the ink layer 1 composed of the composition 1 at a solid content of 2.0 g / m ^2.
by coating the ink layer 2 so that m ^2, to form a thermal transfer ink layer to give a thermal transfer sheet of Example 1.

Ink layer composition 1 (hue is black) Carbon black aqueous dispersion (solid content 30%) 15 parts Styrene-butadiene latex (solid content 50%, Tg 20 ° C.) 70 parts Carnauba wax aqueous dispersion (solid content 40) %) 15 parts

Ink layer composition 2 (hue is red) Carmine 6B aqueous dispersion (solid content 20%) 20 parts Paraffin wax aqueous dispersion (melting point 62 ° C., solid content 40%) 80 parts

(Example 2) Using the thermal transfer sheet of Example 1 above, a temporary adhesive having the following composition was applied onto the thermal transfer ink layer by gravure coating so that the coating amount during drying was 0.5 g /
After coating so as to obtain m ² , the ink receiving surface and the temporary adhesive layer were bonded to each other using a transfer object under the following conditions to obtain an integrated thermal transfer sheet of Example 2 of the present invention. However, the bonding conditions are a nip temperature of 50 ° C. and a nip pressure of 5 kg / cm ^2.
And

Temporary adhesive layer composition Acrylic adhesive resin dispersion 10 parts (solid content 40%, glass transition temperature -58 ° C.) Carnauba wax aqueous dispersion 40 parts (solid content 40%, melting point 82 ° C.) Water 10 Parts isopropanol 20 parts

<Preparation of Transferred Body> A coated paper having a basis weight of 84 g / m ² was used as a transferred body.

(Example 3) The ink layers 1 and 2 of the thermal transfer ink layer of the thermal transfer sheet used in Example 1 were changed to the ink layers 3 and 4 having the following composition. The layer 3 was changed to the ink layer 4 and the ink layer 2 was changed to the ink layer 4. Further, without using the temporary adhesive layer of Example 2,
Under the same conditions as described above, an integrated thermal transfer sheet of Example 3 was prepared. (Because the thermal transfer ink layer 4 contains particles having adhesive properties)

Ink layer composition 3 (hue is black) Carbon black 5 parts Polyester resin (Tg 67 ° C.) 5 parts Carnauba wax dispersion (solid content 20%, melting point 82 ° C.) 40 parts Methyl ethyl ketone 25 parts Toluene 25 parts

Ink layer composition 4 (hue is yellow) Disazo yellow aqueous dispersion (solid content 20%) 20 parts Candelilla wax aqueous dispersion (solid content 30%, melting point 62 ° C.) 60 parts ethylene-vinyl acetate copolymer 20 parts of aqueous dispersion of coalesced particles (solid content 30%, minimum film formation temperature 70 ° C)

Example 4 The ink layers 1 and 2 of the thermal transfer ink layer of the thermal transfer sheet used in Example 1 were changed to ink layers 5 and 6 having the following compositions. That is, the ink layer 1 was changed to the ink layer 5 and the ink layer 2 was changed to the ink layer 6. Otherwise, the procedure of Example 2 was repeated to prepare an integrated thermal transfer sheet of Example 4.

Ink layer composition 5 (hue is black) Carbon black aqueous dispersion (solid content 30%) 20 parts Microcapsule aqueous dispersion 30 parts (solid content 20%, core Tg 0 ° C, shell Tg 60 ° C) Carnauba wax emulsion (Solid content 40%, melting point 82 ° C) 50 parts

Ink layer composition 6 (hue is red) Carmine 6B aqueous dispersion (solid content 20%) 20 parts Paraffin wax emulsion (solid content 30%, melting point 67 ° C.) 70 parts Styrene-butadiene latex (solid content 40%) , Tg 0 ° C) 10 parts

Example 5 An integrated thermal transfer sheet of Example 5 was prepared in the same manner as in Example 2 except that the transfer object used in Example 2 was changed to the following. Basis weight 64g /
by applying a following ink layer composition 7 to the ink receiving surface A3 coated paper of m ² such that 15 g / m ² in solid content was transferred object.

Ink layer composition 7 Disazo Yellow 10 parts Kaolin 40 parts Calcium carbonate 15 parts Styrene-butadiene rubber latex (solid content 50%, Tg = 0 ° C.) 35 parts Ink layer 7 contains styrene-butadiene rubber latex The above filler was dispersed therein, dried at 90 ° C., and adjusted to a solid content of 15 g / m ² .

(Comparative Example 1) Thermal transfer sheet used in Example 1
Into a single layer of the ink layer 8 having the following composition
changed. Other than that, the same as in Example 2
A body type thermal transfer sheet was prepared. Ink layer composition 8 Carbon black 15 parts Carnauba wax (melting point 82 ° C) 20 parts Paraffin wax (melting point 65 ° C) 50 parts Ethylene-vinyl acetate copolymer (MI = 400, VA = 20%) 15 parts

Using the integrated thermal transfer sheets of Examples and Comparative Examples described above, the thermal transfer sheets were set in a prototype printer,
0.3 mj / dot and 1.0 at 50 ° C and 50% RH
By applying two types of energy, mj / dot, to the thermal head, a desired image was formed on the transfer medium, and the print quality, hue stability, and the number of hues that could be expressed were examined. However, the thermal head is 300 dpi and the printing pressure is 4 kg /
A4 width (210 mm). In Comparative Example 1, an energy of 0.5 mj / dot was applied to the thermal head. In Example 1, the above-described printing was performed by superimposing a transferred body of coated paper having a basis weight of 84 g / m ^{2 on} the prepared thermal transfer sheet of Example 1. The evaluation method is as follows.

(Print Quality) After printing with a prototype printer in an environment of 25 ° C. and 50% RH, the quality (presence or absence of voids in a solid print portion, etc.) was visually evaluated. The criteria are as follows. ：: good. X: Printing failure occurs. (There are voids in the solid part.)

(Hue Stability) After printing with a prototype printer in an environment of 25 ° C. and 50% RH, the printed matter was visually evaluated for color reproducibility of each layer and occurrence of color mixing. The criteria are as follows. ：: The hue of each layer was reproduced and good. X: Color mixture was recognized and defective.

(Number of hues that can be expressed) 25 ° C., 50% R
After printing with a prototype printer in the environment of H, the number of hues expressed on the printed matter was visually checked. However, the background color of the transfer target paper itself is not included in the number. In the transfer member of Example 5, since the ink layer (colored layer) was provided on the paper, 1
Color.

The evaluation results are shown in Table 1 below.

[Table 1]

[0060]

According to the present invention, as described above,
The thermal transfer sheet of the present invention has a thermal transfer ink layer formed on one surface of a base film, the thermal transfer ink layer is composed of two or more layers, the hue of each layer is different, and the thermal transfer ink layer All layers having different hues are transferred, and at the time of high energy, substantially only the outermost layer is transferred. That is, when low energy is applied to the thermal transfer sheet, the thermal transfer sheet is peeled off at the interface between the base film and the thermal transfer ink layer, and all of the two or more thermal transfer ink layers are transferred to the transfer object. When high energy is applied to the thermal transfer sheet, the thermal transfer sheet peels off at the interface between the ink layers of the thermal transfer ink layer composed of two or more layers (at the interface between the outermost layer and the layer adjacent to the outermost layer), and Only is transferred to the transfer object. Therefore, by changing the applied energy, it is possible to record a plurality of colors (multicolors) on the transfer object.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view illustrating another embodiment of the thermal transfer sheet of the present invention.

FIG. 3 is a diagram schematically illustrating a cross section of a mechanism in which one layer of a thermal transfer ink layer of the integrated thermal transfer sheet of the present invention is transferred.

FIG. 4 is a diagram schematically illustrating a cross section of a mechanism where two layers of a thermal transfer ink layer of the integrated thermal transfer sheet of the present invention are transferred.

FIG. 5 is a diagram schematically illustrating a cross section of a mechanism in which three thermal transfer ink layers of the integrated thermal transfer sheet of the present invention are transferred.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 thermal transfer sheet 2 integrated thermal transfer sheet 3 object to be transferred 4 substrate film 5 thermal transfer ink layer (substrate film side) 6 thermal transfer ink layer (outermost layer) 7 thermal transfer ink layer (middle) 8 back layer 9 substrate 10 receiving layer 11 Temporary adhesive layer 12 Thermal head

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C068 AA06 AA15 AA21 BB04 BB08 BB19 BB22 BB26 BB27 BB34 BC03 BD17 BD27 BD31 BD49 2H111 AA26 AA33 AA43 AA47 AB01 BA03 BA12 BA62

Claims (7)

[Claims] 1. A thermal transfer sheet having a thermal transfer ink layer formed on one surface of a substrate film, wherein the thermal transfer ink layer comprises two or more layers, and each layer has a different hue;
A thermal transfer sheet wherein all layers having different hues of the thermal transfer ink layer are transferred at low energy, and substantially only the outermost layer is transferred at high energy. 2. The thermal transfer sheet according to claim 1, wherein the outermost layer of the thermal transfer ink layer has a bright hue, and the bright color is transferred at high energy. 3. An integrated thermal transfer sheet, characterized in that the thermal transfer sheet according to claim 1 or 2 is temporarily bonded to a transfer object and releasably bonded. 4. The integrated thermal transfer sheet according to claim 3, wherein a temporary adhesive layer is provided between the thermal transfer ink layer and the transfer object. 5. The integrated thermal transfer sheet according to claim 3, wherein an adhesive component is contained in the thermal transfer ink layer on the transfer object side. 6. The thermal transfer sheet according to claim 1 or 2, or the integrated thermal transfer sheet according to any one of claims 3 to 5, wherein the energy applied from a thermal head is varied. A recording method for recording a plurality of colors on an object to be transferred. 7. The thermal transfer sheet according to claim 1 or 2, or the integrated thermal transfer sheet according to any one of claims 3 to 5, wherein a transfer is performed by a single scan from a thermal head. A recording method characterized by recording a plurality of colors on a body.