JPH05131767A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE:To provide a co-wound thermal transfer sheet excellent in both of adhesiveness and releasability, imparting a printing image of high resolving power and capable of performing printing of two or more colors generating no background staining. CONSTITUTION:In a thermal transfer sheet constituted by releasably joining a thermal transfer sheet A wherein a hot-melt ink layer 2 is formed to one surface of a base material film 1 to thermal color forming paper B through an adhesive layer C, the adhesive layer C is composed of adhesive particles.

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, and more particularly to a co-rolled thermal transfer sheet on which a thermal transfer sheet and a thermosensitive coloring paper are preliminarily adhered to each other and capable of forming images of two or more colors.

[0002]

2. Description of the Related Art Conventionally, when printing an output print of a computer or a word processor by a thermal transfer method, a thermal transfer sheet having a heat-fusible ink layer on one surface of a base film is used. This conventional thermal transfer sheet is a substrate film having a thickness of 10 to 20 μm, such as condenser paper or paraffin paper, or a thickness of 3 to 20 μm.
This is manufactured by using a film of plastic such as polyester or cellophane having a thickness of .mu.m and coating a hot-melt ink layer in which a coloring agent such as a pigment or a dye is mixed with wax. When printing on a transfer sheet using these conventional thermal transfer sheets, the thermal transfer sheet is supplied from a roll around which the thermal transfer sheet is wound, while a continuous or sheet-shaped transfer material is supplied and both are placed on a platen. In this state, heat is applied from the back surface of the thermal transfer sheet with a thermal head to melt transfer the ink layer to form a desired image.

[0003]

[Problems to be solved by the invention] However,
When it is required to form an image of two or more colors using these thermal transfer sheets, a thermal transfer sheet of two or more colors or a thermal transfer sheet in which inks of two or more colors are separately applied in a frame order is required. It is required to repeat the thermal transfer operation twice or more on the transfer surface of the same transfer material. As a method for solving such complexity, a so-called thermosensitive coloring paper is used as a material to be transferred, and an ink layer is transferred from the thermal transfer sheet to the coloring surface of the material. At this time, the hue of the ink layer of the thermal transfer sheet and the thermal coloring paper A method has been proposed in which an image of two or more colors is easily formed by combining different hues (for example, Japanese Patent Publication No. 3-25355 and 3).
-32476 publication etc.).

[0004]

[Problems to be solved by the invention] However,
In the above method, it is necessary to perform printing by the thermal head twice or more by changing the heat generation condition of the thermal head. At this time, if the positions of the thermal transfer sheet and the thermosensitive coloring paper are slightly misaligned, a fine image is formed. There is the problem of becoming difficult. As a method of solving such a problem, it is desirable to temporarily bond the thermal transfer sheet and the thermosensitive coloring paper in advance and wind them in a roll shape (co-rolling). However, in the case of such a co-rolling thermal transfer sheet, Does not cause wrinkles or misalignment on the thermal transfer sheet due to the firm adhesion between the thermal transfer sheet and the thermal color developing paper, and they easily separate after thermal transfer, and the ink layer in the transfer area is accurately transferred to the thermal color developing paper. In addition, it is required that the transferred area is not transferred at all and the thermosensitive color developing paper is not contaminated. On the other hand, in the case of the conventional co-winding thermal transfer sheet, none of them can sufficiently satisfy such requirements. Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, to have excellent adhesiveness and releasability, and a co-wound thermal transfer sheet capable of printing two or more colors without resolution of printed images and background stains. Is to provide.

[0005]

The above object can be achieved by the present invention described below. That is, the present invention relates to a thermal transfer sheet comprising a substrate and a heat transfer ink layer formed on one surface of a substrate film and a thermosensitive color developing paper, which are releasably adhered to each other by an adhesive layer. A thermal transfer sheet, wherein the layer is composed of adhesive particles.

[0006]

[Function] By forming the adhesive layer from a granular pressure-sensitive adhesive, the thermal transfer sheet and the thermosensitive coloring paper are firmly adhered to each other without causing wrinkles or deviations, and after thermal transfer, they are easily peeled off and transferred. There is provided a thermal transfer sheet in which the ink layer is accurately transferred to the thermosensitive color developing paper in the area and the non-transfer area is not transferred at all, and the thermosensitive color developing paper is not contaminated.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in more detail with reference to the preferred embodiments. A cross-sectional view of a preferred example of the thermal transfer sheet of the present invention is shown in FIG. The thermal transfer sheet of the present invention is a thermal transfer sheet in which a thermal transfer sheet A and a thermosensitive coloring paper B are releasably adhered by an adhesive layer C as shown in the figure, and the adhesive layer C has the constitution described below. ing. The thermal transfer sheet A has a heat-fusible ink layer 2 formed on a substrate film 1 as shown in the drawing, and if necessary, a mat layer 3 and / or a peeling layer between the substrate film 1 and the ink layer 2. A layer 4 is formed, and a slip layer 5 is formed on the back side.

As the base material film used in the thermal transfer sheet of the present invention, the same base material film as that used in the conventional thermal transfer sheet can be used as it is, and other materials can also be used. Not limited. Specific examples of preferable substrate film include, for example, polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride, polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin, chlorinated rubber, ionomer and the like. Plastics, condenser paper, paper such as paraffin paper, non-woven cloth, woven cloth, etc.,
Further, it may be a base film in which these are combined. The thickness of this base film can be appropriately changed according to the material so that its strength and thermal conductivity are appropriate.
The thickness is preferably, for example, 2 to 25 μm.

The heat-fusible ink layer provided on the substrate film may be composed of a colorant and a vehicle, and may further contain various additives if necessary. The colorant is preferably an organic or inorganic pigment or dye having good properties as a recording material, for example, a pigment having a sufficient coloring density and not fading due to light, heat, temperature or the like. Of course, carbon black is preferable for black monochromatic printing, and cyan, magenta, and
A chromatic colorant such as yellow is used. The amount of these colorants used is generally preferably about 5 to 70% by weight in the ink layer. As the vehicle, a mixture containing wax as a main component and other wax and a drying oil, a resin, a mineral oil, a derivative of cellulose, a rubber or the like is used.

Typical waxes include microcrystalline wax, carnauba wax and paraffin wax. Furthermore, various types of Fischer-Tropsch wax, various low-molecular-weight polyethylene, wood wax, beeswax, spermaceti wax, ivowa wax, wool wax, shellac wax, candelilla wax, petrolactam, polyester wax, partially modified wax, fatty acid ester, fatty acid amide, etc. Wax is used. In the present invention, the above wax is further mixed with a thermoplastic resin having a relatively low melting point,
It is possible to improve the adhesion of the ink to the thermosensitive coloring paper. Examples of the method for forming the hot melt ink layer on the base film include hot melt coating, hot lacquer coating, gravure coating, gravure reverse coating, roll coating and many other means. The thickness of these ink layers may be several μm as in the conventional case.
When forming the ink layer, the mat layer 3 having a thickness of about 0.1 to 20 μm is formed on the surface of the base film.
Matte can be given to the printed matter. Alternatively, the release layer 4 made of wax may be previously formed on the surface of the base film or the mat layer, and the release layer may be used as a surface protective layer for a transferred image after transfer. The release layer may be formed by hot melt coating, hot lacquer coating or emulsion coating. Such a release layer is generally 0.1-5.
It has a thickness of about μm.

The thermosensitive color developing paper B itself is conventionally known,
Any conventionally known thermosensitive coloring paper can be used as the transfer material of the present invention. These thermosensitive coloring papers are those in which a coloring layer containing a colorless dye that is colored by an acid and a solid acid that is a color developer is provided on the surface of the paper that is a base material,
In such a color-developing layer, the dye and the color developer may be divided into separate layers, or they may be mixed in one layer.
The dye and / or the developer may be microencapsulated by a shell material that is destroyed by heat in order to improve stability. Typical examples of dyes include crystal violet lactone and 3-diethylamino-6.
-Methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-indolino-3-p-dimethylaminophenyl-6-dimethylaminophthalide and the like, but of course, It is not limited to these dyes. In addition, as a typical example of the color developer, 4,4 '
-Phenolic properties such as isopropylidene diphenyl, 4,4'-isopropylidene bis (2-chlorophenol), 4,4'-isopropylidene bis (2-tert-butylphenol), 4-phenylphenol, 4-hydroxydiphenoxide There are substances, but of course
It is not limited to these phenols.

Each of the dyes and the color developers as described above can form a color of any hue and form a color forming layer at any color forming temperature depending on the kind and combination thereof. For example, it may be a color-forming layer that does not develop color at the transfer temperature of the ink layer of the thermal transfer sheet and develops color at the transfer temperature or higher, or a color-forming layer that develops color at a temperature lower than the transfer temperature of the ink layer. In the former case, an image of two colors is formed, that is, an ink image formed by transferring the ink layer and an image formed by a mixed color of the coloring hue of the coloring layer and the coloring of the ink layer, and in the latter case, a coloring image formed by the coloring layer. And a color of the ink layer, a two-color image is formed. Particularly in the former case, the coloring portion of the coloring paper, which is inferior in durability, is covered with the ink layer, so that the overall durability is good, which is preferable. Further, a transparent protective layer may be formed on the surface of the coloring layer of the thermosensitive coloring paper. Furthermore, the size of these thermosensitive coloring papers is A version,
Although it may be a sheet such as B plate, it is preferably a continuous sheet having an arbitrary width.

The constitution of the adhesive layer C for temporarily adhering the thermal transfer sheet A and the thermosensitive coloring paper B characterizes the present invention. The adhesive layer C is characterized by being composed of pressure-sensitive adhesive particles. A particularly preferable adhesive is composed of sticky resin particles having a low glass transition temperature and wax particles. The adhesive force (g) of the adhesive layer composed of such particles is 2
A sample of 5 mm (width) x 55 mm (length) is cut out, and it is 1800 mm / min. The range of 300 to 2,000 g is preferable when measured at a pulling speed of. When the adhesive force is less than the above range, the adhesive force between the thermal transfer sheet and the transfer material is too low, the two are easily separated, and the thermal transfer sheet is more likely to be wrinkled. When the adhesive force exceeds the above range, the adhesive force is sufficient, but the ink layer is easily transferred to the transfer material even in the non-printed portion, and the transfer material is contaminated. However,
When the amount of thermoplastic resin in the ink layer is, for example, ethylene-vinyl acetate copolymer having a vinyl acetate content of 28%, the solid content in the ink layer is 9% by weight or more, the base film and the ink layer. Because the adhesiveness with is so high,
The adhesive force of the adhesive layer to the transfer material is 1,300 to 2,
Even in the case of the range of 000 g, it is possible to obtain a thermal transfer sheet which does not cause contamination of the material to be transferred.

The glass transition temperature of the adhesive resin is -90.
C. to -60.degree. C. is preferable, and examples of such adhesive resin particles include rubber adhesive resin, acrylic adhesive resin and silicone adhesive resin, and morphologically. Is an aqueous or oily emulsion type, and any of them can be used in the present invention, but an acrylic aqueous emulsion type is particularly preferable in the present invention. When the above-mentioned adhesive resin is used alone, excellent adhesiveness is obtained, but the releasability of the transferred material is insufficient and non-uniform, and it may occur unexpectedly before thermal transfer such as during production, storage and transportation. When a force is applied, there is a problem that the ink layer of the thermal transfer sheet is transferred to the material to be transferred and scumming occurs. Further, during thermal transfer, foil breakage of the ink layer is inferior, and for example, the ink layer is transferred to the periphery of the heat application area by the thermal head, and the resolution of the transferred image is inferior. In the present invention, the above problem is caused by adding an emulsion of wax particles as used in the formation of the ink layer to the emulsion adhesive resin particles, whereby the adhesiveness can be adjusted within a preferable range, and the problem of the background stain occurs. It was found that the foil breakage of the adhesive layer C was improved and the resolution of the transferred image was significantly improved. The weight ratio of the adhesive resin to the wax is preferably 1: 0.5 to 4, and if it is out of this range, various problems as described above are likely to occur, which is not preferable. .

Further, as shown in FIG. 3, by adding the emulsion of the resin particles 9 having a higher glass transition temperature to the mixture of the emulsion of the adhesive resin particles 8 and the emulsion of the wax 10, the adhesiveness is improved. It is also possible to easily adjust to a preferable range. Examples of such resin emulsion include ethylene-vinyl acetate copolymer, ethylene-acrylic ester copolymer, polyethylene, polystyrene, polypropylene, polybutene, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, acrylic resin. Thermoplastic resins such as, especially acrylic emulsions are suitable. Such a resin preferably has a glass transition temperature higher than that of the adhesive resin, for example, a glass transition temperature of 60 ° C. or higher, and may be a thermosetting resin in some cases. The weight ratio of the adhesive resin, the resin having a high Tg, and the wax is preferably 3-5: 1 to 2: 3-5. Further, when beads or particles having a large particle size are added to the above-mentioned pressure-sensitive adhesive to bring the material to be transferred to a point-adhesive state, if the material to be transferred is unclean, for example, in the case of the present invention, It is preferable to use a transparent transfer material such as a sheet for OHP, a sheet for OHP, or a tracing paper, and these transfer materials are not contaminated. The adhesive layer C composed of the above components may be provided on the surface of the material B to be transferred, but in this case, since the printed matter remains tacky, it is preferably provided on the surface of the ink layer 2 of the thermal transfer sheet. In this case, since the adhesive resin is used as an aqueous emulsion, it is preferable because it does not damage the ink layer. The coating method and drying method of the emulsion are not particularly limited. The adhesive layer preferably has a thickness of 0.1 to 20 μm (solid coating amount of 0.1 to 5 g / m ² ). The heat transfer sheet A and the heat sensitive color developing paper B are preferably adhered by continuously adhering the heat sensitive color developing paper while forming an adhesive layer on the surface of the ink layer of the heat transfer sheet, and winding it into a roll. When winding, the thermosensitive coloring paper may be placed outside or the thermal transfer sheet may be placed outside, and these may be cut into sheets.

The above is the basic constitution of the co-rolled thermal transfer sheet of the present invention. Of course, as shown in FIG. 1, a slip layer 5 for preventing the thermal head from sticking and improving the slipperiness is provided on the back surface of the thermal transfer sheet. Any of the well-known techniques in the thermal transfer sheet field, such as providing or providing a peeling layer 4 between the base film and the ink layer to impart scratch resistance to printing, making the ink layer a hue other than black, etc. Can also be added to the thermal transfer sheet of the present invention. The thermal transfer sheet of the present invention described above, for example, set in a facsimile printer,
The desired image of two or more colors, that is, 7'and 7 is printed on the thermosensitive coloring paper B by conveying the thermosensitive coloring paper B after printing by changing the amount of heat applied by the thermal head 6 as shown by the arrow in FIG. "Is formed.

[0017]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples. In the text, “part” or “%” is based on weight unless otherwise specified. Example 1 A 6.0 μm-thick polyethylene terephthalate film having a slip layer provided on the back surface was used as a base film, and one surface thereof was coated with the following ink composition at a rate of 4 g / m ^2. , And an ink layer was formed. Ink composition Carbon black 15 parts Ethylene / vinyl acetate copolymer 8 parts Paraffin wax 50 parts Carnauba wax 25 parts (prepared by kneading at 120 ° C for 4 hours at an attritor) Furthermore, a temporary adhesive having the following composition on the above ink layer Was applied by a gravure coating method at a coating amount of 0.5 g / m ² when dried, and then thermosensitive coloring paper (dye: crystal violet lactone, developer: 4.4'-isopropylidenediphenyl). Nip (nip temperature 50 ° C, nip pressure 500
Kg), and the co-rolled thermal transfer sheet of the present invention was obtained. Temporary adhesive composition Acrylic adhesive particles Water-based dispersion (solid content 40%, glass transition temperature -70 ° C, particle size 3 to 10 µm) 10 parts Acrylic resin particle water-based dispersion (solid content 20%, glass transition temperature 85 ° C) , Particle size 0.2 to 0.3 μm) 15 parts Carnauba wax aqueous dispersion (solid content 40%, melting point 83 ° C.) 15 parts Water 10 parts Isopropanol 30 parts

Examples 2 to 4 Using the same dispersions as in Example 1, the composition (weight ratio) of the temporary adhesive was changed as shown in Table 1 below. A thermal transfer sheet was obtained. Example 5 The ink composition in Example 1 was replaced with an ink composition having the following composition, the composition (weight ratio) of the temporary adhesive was changed as shown in Table 1 below, and the thermosensitive coloring paper was changed to red coloring paper (dye: 3). A co-wound thermal transfer sheet of the present invention was obtained in the same manner as in Example 1 except that -diethylamino-5-methyl-7-chlorofluorane and a developer: 4,4 'isopropylidenediphenol) were used. Ink composition Blue azo pigment 17 parts Ethylene / vinyl acetate copolymer 10 parts Paraffin wax 50 parts Carnauba wax 24 parts (Prepared by kneading at 120 ° C for 4 hours in an attritor)

[0019]

[Table 1]

Comparative Example 1 A thermal transfer sheet of Comparative Example was obtained in the same manner as in Example 1 except that only the adhesive particle dispersion in Example 1 was used as the temporary adhesive. Comparative Example 2 The thermal transfer sheet of Comparative Example was prepared in the same manner as in Example 1 except that the adhesive particles and the resin particles were used as the temporary adhesive in Example 1 in a weight ratio of 1: 1 and no wax was used. Obtained. Comparative Example 3 A temporary adhesive layer was formed of polyvinyl alcohol. Comparative Example 4 A temporary adhesive layer was formed with a polyurethane adhesive. (Each of the temporary adhesive layers of the above Comparative Examples has a thickness of 0.5 g / m ² ) The adhesive force between the ink layer and the thermosensitive color developing paper of the thermal transfer sheets of Examples 1 to 5 and Comparative Example above was measured, The results are shown in Table 2. It does not peel easily even if left unattended, it is easily peeled off with a fingertip after printing, and if the paper does not have scumming, it is marked with ○, and if it peels off naturally or scumming occurs, it is marked with x. expressed. From these results, the adhesive strength is 300 to 1,500.
It has been found that g, especially in the range 400 to 800 g, is suitable. The adhesive force (g) between the temporary adhesive layer and the thermosensitive coloring paper is 25 mm (width) x 55 mm (length), and a sample is cut into a sliding friction measuring machine (HEIDON-14, manufactured by Shinto Kagaku). 1,800 mm / min. The pulling speed was measured.

[0021]

[Table 2] * 1: Without measuring adhesive strength. Use Example 1 Using the co-rolled thermal transfer sheets of Examples 1 to 4, the printing speed was fixed at 15 msec / line, the thermal head applied energy was 1200 μsec, printing was performed every other line, and then the applied energy was 500 μsec. When the unprinted portion was printed and the thermal transfer sheet was peeled off after printing was completed, a black ink print and a blue color print were formed every other line, and a clear print image without background stain was obtained. USE EXAMPLE 2 Using the co-rolled thermal transfer sheet of Example 5, printing speed is 15
Fixed at msec / line, the thermal head applied energy was 500 μsec and the thermosensitive color paper was printed without transferring the ink layer, then the applied energy was 1200 μsec and the ink layer was transferred and developed at the same time. After that, when the heat transfer sheet was peeled off, blue color printing and black (color mixture of red and blue) printing were formed every other line, and a clear printed image without background stain was obtained.

[0022]

[Effects] According to the present invention as described above, by constituting the adhesive layer with a specific adhesive, the thermal transfer sheet and the thermosensitive color developing paper are firmly adhered to each other without causing wrinkles or deviations, and after thermal transfer. It is possible to provide a thermal transfer sheet in which both are easily separated, the ink layer is accurately transferred to the thermosensitive coloring paper in the transfer area, and the non-transfer area is not transferred at all, and the thermosensitive coloring paper is not contaminated.

[Brief description of drawings]

FIG. 1 is a diagram schematically illustrating a cross section of a thermal transfer sheet of the present invention.

FIG. 2 is a diagram schematically illustrating a cross section of a transfer mechanism of the thermal transfer sheet of the present invention.

FIG. 3 is a diagram schematically illustrating a structure of an adhesive layer.

[Explanation of symbols]

 A: Thermal transfer sheet B: Thermosensitive coloring paper C: Adhesive layer 1: Substrate film 2: Ink layer 3: Matt layer 4: Release layer 5: Slip layer 6: Thermal head 7 ': Ink image 7 ": Ink image and Mixed colored portion of color image 8: Adhesive particle 9: Resin particle 10: Wax particle

Claims (7)

[Claims] 1. A thermal transfer sheet comprising a base film and a thermosensitive ink layer formed on one surface of the base film, and a thermosensitive coloring paper releasably adhered to each other by an adhesive layer. Is a pressure-sensitive adhesive particle. 2. The thermal transfer sheet according to claim 1, wherein the adhesive layer comprises pressure-sensitive adhesive particles having a low glass transition temperature and wax particles. 3. The thermal transfer sheet according to claim 1, wherein the adhesive layer comprises adhesive particles having a low glass transition temperature, resin particles having a high glass transition temperature, and wax particles. 4. The glass transition temperature of the pressure-sensitive adhesive is from −90 ° C.
It is in the range of -60 ° C and the glass transition temperature of the resin particles is 6
The thermal transfer sheet according to claim 1, which has a temperature of 0 ° C or higher. 5. The adhesive layer is formed from a dispersion containing adhesive particles, resin particles and wax particles.
The thermal transfer sheet described in. 6. The thermal transfer sheet according to claim 1, wherein the transfer temperature of the ink layer is lower than the color development temperature of the thermosensitive color paper. 7. The thermal transfer sheet according to claim 1, wherein the transfer temperature of the ink layer is higher than the color development temperature of the thermosensitive color paper.