JP3055792B2 - Thermal transfer sheet - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a thermal transfer sheet, and more particularly, to a novel co-wound thermal transfer sheet in which a thermal transfer sheet and a material to be transferred, such as paper, are temporarily bonded in advance.

(Conventional technology and its problems) Conventionally, when printing an output print of a computer or a word processor by a thermal transfer method, a thermal transfer sheet provided with a heat-meltable ink layer on one surface of a base film is used. .

This conventional thermal transfer sheet has a thickness as a base film.
Using a 10-20 μm thick paper such as condenser paper or paraffin paper or a 3-20 μm thick plastic film such as polyester or cellophane, a wax is mixed with a coloring agent such as a pigment or dye to form a hot-melt ink layer. It is manufactured by coating.

When printing on transfer paper 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-transfer material is supplied, and both are supplied on a platen. In this state, heat is applied from the back of the thermal transfer sheet by a thermal head to melt-transfer the ink layer to form a desired image.

However, even if these thermal transfer sheets are diverted to, for example, a facsimile printer using conventional thermosensitive coloring paper, in the facsimile printer described above, since the recording paper itself thermally develops color, there is no transfer device for the material to be transferred, and the diverting is impossible. Such a problem also applies to a special printer such as a large plotter.

As a method of solving the above-mentioned problem, by temporarily bonding the thermal transfer sheet and the transfer-receiving material in advance and winding them in a roll shape, or adapting to a facsimile printer or the like,
Further, methods for simplifying and reducing the size of the device have been devised.

In the case of such a co-winding thermal transfer sheet, the thermal transfer sheet and the paper are firmly adhered to each other, and the thermal transfer sheet does not generate wrinkles or deviations, and easily peel off after thermal transfer,
The transfer area is required to have a performance in which the ink layer is accurately transferred to the paper, and the transfer area does not transfer at all and does not contaminate the paper. On the other hand, in the case of the conventional co-winding thermal transfer sheet, none of these requirements can be sufficiently satisfied.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide a co-wound thermal transfer sheet which is excellent in both adhesiveness and releasability, and has no printed image resolution and background contamination.

(Means for Solving the Problems) The above object is achieved by the present invention described below. That is,
The present invention provides a thermal transfer sheet in which a thermal transfer sheet having a heat-fusible ink layer formed on one surface of a base film and a transfer-receiving material are releasably bonded by an adhesive layer.
The adhesive layer is composed of pressure-sensitive adhesive particles, resin particles, and wax particles, and the weight ratio of pressure-sensitive adhesive particles: resin particles: wax particles is 3 to 5: 1 to 2.5: 3 to 5; Cut out a sample of 25mm (width) x 55mm (length) with an adhesive force (g) to the material to be transferred.
-14, manufactured by Shinto Kagaku Co., Ltd.), and when measured at a pulling speed of 1800 mm / min., It is in the range of 300 to 1500 g.

(Operation) The adhesive layer is composed of pressure-sensitive adhesive particles, resin particles, and wax particles, and the weight ratio of pressure-sensitive adhesive particles: resin particles: wax particles is 3 to 5: 1 to 2.5: 3 to 5, and thermal transfer is performed. By setting the adhesive force (g) between the sheet and the material to be transferred within the range of 300 to 1500 g, the thermal transfer sheet and the paper are firmly adhered to each other, and no wrinkles or deviations occur. A thermal transfer sheet is provided which does not contaminate the paper by peeling and transferring the ink layer accurately to the paper in the transfer area and not transferring the transfer area at all.

(Preferred Embodiment) Next, the present invention will be described in more detail with reference to preferred embodiments.

FIG. 1 is a sectional view of a preferred example of the thermal transfer sheet of the present invention.
Shown in the figure.

The thermal transfer sheet of the present invention comprises a thermal transfer sheet A as shown in the figure.
And a material to be transferred B, which are releasably adhered by an adhesive layer C, wherein the adhesive layer C is formed from adhesive particles, resin particles and wax particles. : The weight ratio of the wax particles is set to 3 to 5: 1 to 2.5: 3 to 5, and the adhesive force (g) between the thermal transfer sheet and the material to be transferred by the adhesive layer C is in the range of 300 to 1500 g. It is characterized by.

In the thermal transfer sheet A, a heat-meltable ink layer 2 is formed on a base film 1 as shown, a mat layer 3 is provided between the base film 1 and the ink layer 2 if necessary, and Has a slip layer 4 formed thereon.

As the substrate film used in the thermal transfer sheet of the present invention, the same substrate film as used in the conventional thermal transfer sheet can be used as it is, and other materials can be used without any particular limitation.

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, fluororesin, chloride rubber, ionomer, etc. Plastic, condenser paper,
There are papers such as paraffin paper, non-woven fabric, and the like, and a base film in which these are combined may be used.

The thickness of the base 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.

The hot-melt ink layer provided on the base film is composed of a colorant and a vehicle, and may further contain various additives as necessary.

As the coloring agent, among organic or inorganic pigments or dyes, those having good characteristics as a recording material, for example, those having a sufficient coloring density and not changing brown due to light, heat, temperature and the like are preferable.

Of course, carbon black is preferable for black single-color printing, and chromatic colorants such as cyan, magenta, and yellow are used for multicolor printing. It is generally preferred that these coloring agents be used in a proportion of about 5 to 70% by weight in the ink layer.

As the vehicle, a mixture of wax as a main component, and other components such as a wax and a derivative of a drying oil, a resin, a mineral oil, cellulose, and rubber is used.

Representative examples of the wax include microcrystalline wax, carnauba wax, and paraffin wax. Furthermore, various types of Fischer-Tropsch wax, various low molecular weight polyethylenes, wood wax, beeswax, spermaceti, Ibota 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 wax may be mixed with a thermoplastic resin having a relatively low melting point to improve the adhesiveness of the ink to the material to be transferred and the adhesiveness between the base film and the ink.

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 prior art.

As the material to be transferred B, ordinary high quality paper, plain paper, synthetic paper,
Any sheet or film that can be thermally transferred, such as tracing paper or plastic film, may be used as long as it is used as a conventional transfer material for thermal transfer.
The size of the material to be transferred may be a sheet such as an A plate or a B plate, but is preferably a continuous sheet having an arbitrary width.

The adhesive layer C for temporarily adhering the thermal transfer sheet A and the transfer-receiving material B mainly characterizes the present invention, and the adhesive layer C is formed from an adhesive particle, a resin particle, and a wax particle. The weight ratio of particles: resin particles: wax particles is 3-5: 1-2.5: 3-5, and the adhesive force (g) is 25
Cut out a sample of mm (width) x 55 mm (length) and use a sliding friction meter (HEIDON-14, manufactured by Shinto Kagaku) at 1800 mm / mi
When measured at a pulling speed of n., the range is 300 to 1500 g.

When the adhesive strength is less than the above range, the adhesive strength between the thermal transfer sheet and the material to be transferred is too low, the two easily peel off, and the thermal transfer sheet is more likely to wrinkle. If the adhesive force exceeds the above range, the adhesive force is sufficient, but the ink layer is easily transferred to the non-transfer material even in the non-printed area, and the transfer material is contaminated. A particularly preferred range of adhesion is in the range of 400-800 g. However, the amount of the thermoplastic resin in the ink layer, for example,
In the case of ethylene-vinyl acetate copolymer having a vinyl acetate content of 28%, if the solid content in the ink layer is 9% by weight or more, the transfer material may be contaminated even if the adhesive strength is in the range of 800 to 1500 g. And a thermal transfer sheet free of heat.

The above-mentioned adhesive strength can be achieved by adjusting the adhesive strength of a conventionally known adhesive.In the present invention, the adhesive is composed of pressure-sensitive adhesive particles having a low glass transition temperature, resin particles having a high glass transition temperature, and wax particles. And

The glass transition temperature of the pressure-sensitive adhesive is preferably in the range of -90 ° C to -60 ° C. Examples of such a pressure-sensitive adhesive include a rubber-based pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, and a silicone-based pressure-sensitive adhesive. In addition, morphologically, there are solvent solution type, aqueous solution type, hot melt type, aqueous or oily emulsion type, any of which can be used in the present invention, but those particularly preferred in the present invention are acrylic It is an aqueous emulsion type, and its particle size is about 0.2 to 10 μm, and a preferable range is 1 to 6 μm. By using such an emulsion-type adhesive, the adhesive 5 of the adhesive layer maintains the particle shape as shown in FIG.

When the above-mentioned pressure-sensitive adhesive is used alone, excellent adhesiveness is obtained, but the peelability of the material to be transferred is insufficient and non-uniform, and unexpected force before thermal transfer during production, storage, transportation, etc. However, there is a problem that the ink layer of the thermal transfer sheet is transferred to the material to be transferred to cause background contamination. In addition, the foil of the ink layer is inferior at the time of thermal transfer. For example, the ink layer is transferred to the periphery of the area to which heat is applied by the thermal head, and the resolution of the transferred image is inferior.

In the present invention, the above problem can be adjusted to a preferable range by adding a resin emulsion containing fine resin particles, for example, a resin particle 6 having a particle diameter of about 0.01 to 0.5 μm to the emulsion adhesive. In addition, the problem of the background stain is solved, and the addition of the wax emulsion 7 used in the formation of the ink layer improves the breakage of the foil of the adhesive layer C and significantly improves the resolution of the transferred image. I found to do.

Examples of the above resin emulsion include ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, polyethylene, polystyrene, polypropylene, polybutene, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, acrylic resin, and the like. Thermoplastic resins, especially acrylic emulsions are preferred. Such resin particles preferably have a glass transition temperature higher than that of the pressure-sensitive adhesive, for example, a glass transition temperature of 60 ° C. or higher, and in some cases, may be thermosetting resin particles.

The wax emulsion is obtained by emulsifying the above-described wax by a known method, and the finer the particle diameter, the better, but not particularly limited.

The weight ratio of the pressure-sensitive adhesive, resin particles and wax is 3 to 5:
The ratio is preferably from 1 to 2.5: 3 to 5, and if it is out of this range, various problems as described above are likely to occur, which is not preferable.

The adhesive layer C composed of the above components may be provided on the surface of the material to be transferred B. However, in this case, the adhesiveness is left on the printed matter, so it is preferably provided on the surface of the ink layer 2 of the thermal transfer sheet. In this case, since the adhesive is used as an aqueous emulsion, it is preferable without damaging the ink layer. The method of applying and drying the emulsion is not particularly limited, but the drying is preferably performed at a low temperature so that the emulsion particles remain.

The adhesive layer has a thickness of 0.1 to 20 μm (as a solid coating amount)
A thickness of 0.1-5 g / m ² ) is preferred.

Adhesion between the thermal transfer sheet A and the transfer material B is preferably performed by continuously bonding the transfer material while forming an adhesive layer on the surface of the ink layer of the thermal transfer sheet, and winding the roll material into a roll. In winding, the material to be transferred may be on the outside, the thermal transfer sheet may be on the outside, and these may be cut into single sheets.

The above is the basic configuration of the co-winding thermal transfer sheet of the present invention. Of course, as shown in FIG. 1, the slip layer 4 for preventing adhesion of the thermal head and improving the slipperiness is provided on the back surface of the thermal transfer sheet. Any technique known in the field of thermal transfer sheets, such as matte printing by providing a mat layer 3 between the base film and the ink layer, and making the ink layer have a hue other than black, of the present invention. It can be added to a thermal transfer sheet.

The above-described thermal transfer sheet of the present invention is set on, for example, a facsimile printer, conveyed as indicated by an arrow in FIG. A desired image 9 is formed.

Examples Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the following description, parts and% are based on weight unless otherwise specified.

Example 1 A film of polyethylene terephthalate having a thickness of 6.0 μm having a slip layer provided on the back surface was used as a base film, and the following ink composition was coated on one surface at a rate of 4 g / m ² , 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 with an attritor) Further, a temporary adhesive having the following composition is formed on the above ink layer Is applied by gravure coating at a rate of 0.5 g / m ² when dried, and plain paper (basis weight 64 g / m ² , Beck surface smoothness 140se
c.) and a nip (nip temperature: 50 ° C., nip thickness: 500 kg) and bonded to obtain a thermal transfer sheet of the present invention.

Temporary adhesive composition Acrylic adhesive particle water-based dispersion (solid content 40
%, Glass transition temperature -70 ° C, particle size 3-10μm) 10 parts Acrylic resin aqueous dispersion (solid content 20%,
Glass transition temperature 85 ° C, particle size 0.2-0.5μm) 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 respective dispersions as in Example 1, the composition (weight ratio) of the temporary adhesive was changed as shown in Table 1 below. Otherwise in the same manner as in Example 1, a thermal transfer sheet of the present invention was obtained.

Example 5 The ink composition in Example 1 was replaced with the ink composition having the following composition, and the composition (weight ratio) of the temporary adhesive was changed to the following first composition.
The thermal transfer sheet of the present invention was obtained in the same manner as in Example 1 except that the conditions were changed as shown in the table.

Ink composition carbon black 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 with an attritor) Comparative Example 1 A thermal transfer sheet of a comparative example was obtained in the same manner as in Example 1 except that only the pressure-sensitive 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 pressure-sensitive adhesive particles and resin particles were used as a temporary adhesive in Example 1 at a weight ratio of 1: 1 and no wax was used. Obtained.

Comparative Example 3 A temporary adhesive layer was formed with polyvinyl alcohol.

Comparative Example 4 A temporary adhesive layer was formed with a polyurethane-based adhesive. (All the temporary adhesive layers of the above comparative examples have a thickness of 0.5 g / m ² ) The adhesive strength between the ink layer and the paper of the thermal transfer sheets of the above Examples and Comparative Examples was measured, and the results are shown in Table 2. It was shown to. It does not peel off easily even when left, and easily peels off with a fingertip after printing. expressed. From these results, it was found that the adhesive strength was suitably in the range of 300 to 1500 g, particularly 400 to 800 g.

The adhesive force (g) was measured by cutting a sample of 25 mm (width) × 55 mm (length) and using a sliding friction measuring machine (HEIDON-14, manufactured by Shinto Kagaku) at a pulling speed of 1800 mm / min.

(Effects) As described above, according to the present invention, by setting the adhesive force (g) between the thermal transfer sheet and the material to be transferred within the range of 300 to 1500 g, the thermal transfer sheet and the paper are firmly adhered and wrinkled. There is provided a thermal transfer sheet which does not cause any slippage, easily peels off after thermal transfer, accurately transfers the ink layer to the paper in the transfer area, does not transfer the transfer area at all, and does not contaminate the paper. You.

[Brief description of the drawings]

1 and 2 are diagrams schematically illustrating the cross section of the thermal transfer sheet of the present invention, and FIG. 3 is a diagram schematically illustrating the structure of an adhesive layer. A: Thermal transfer sheet, B: Transfer material C: Adhesive layer 1: Base film, 2: Ink layer 3: Matt layer, 4: Slip layer 5: Adhesive particles, 6: Resin particles 7: Wax particles, 8 : Thermal head 9: Image

Claims (5)

(57) [Claims] 1. A heat transfer sheet comprising a heat transfer sheet having a heat fusible ink layer formed on one surface of a base film and a transfer material, which is releasably adhered by an adhesive layer. From the pressure-sensitive adhesive particles, the resin particles, and the wax particles, wherein the weight ratio of the pressure-sensitive adhesive particles: resin particles: wax particles is 3 to 5: 1 to 2.5: 3 to 5; Adhesive strength (g) is 25mm (width) x 55mm
(Length) sample and cut it out with a sliding friction measurement machine (HE
(IDON-14, manufactured by Shinto Kagaku) at a tensile speed of 1800 mm / min. 2. The thermal transfer sheet according to claim 1, wherein the adhesive layer comprises pressure-sensitive adhesive particles having a low glass transition temperature, resin particles having a high glass transition temperature, and wax particles. 3. The glass transition temperature of the pressure-sensitive adhesive is from −90 ° C. to −60 ° C.
2. The thermal transfer sheet according to claim 1, wherein the glass transition temperature is in a temperature range of 60 ° C. or higher. 4. The thermal transfer sheet according to claim 1, wherein the adhesive layer has a thickness of 0.2 to 20 μm. 5. The thermal transfer sheet according to claim 1, wherein the adhesive layer is formed from a dispersion containing pressure-sensitive adhesive particles, resin particles and wax particles.