JP2975404B2 - Single-sheet composite thermal transfer sheet - Google Patents

Description

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

(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 single 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 to be diverted to, for example, a facsimile printer using conventional thermosensitive coloring paper, the facsimile printer does not have a transfer device for the material to be transferred because the recording paper itself thermally develops color. Such a problem also applies to a special printer such as a large plotter.

As a method for solving the above-mentioned problems, by temporarily mounting the thermal transfer sheet and the transfer-receiving material in advance and winding them in a roll shape or by making them into a single-sheet type, or adapted to a facsimile printer or the like, Methods for simplifying and miniaturizing the device have been devised.

In the case of such a composite thermal transfer sheet, there is not much problem with a roll wound, but in the case of a single sheet type,
When the material to be transferred is paper, there is a problem of hygroscopicity, and the composite thermal transfer sheet curls due to moisture absorption due to humidity change,
There is a problem that biting in the printer becomes worse.

Also, in the case of the above-mentioned sheet-fed composite 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 misalignment. It is required that the ink layer transfer accurately to the paper, and that the paper does not contaminate the paper without transferring at all in the receiving area. On the other hand, in the case of the conventional single-sheet type composite 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 objects, to provide a composite thermal transfer sheet which is excellent in both curl prevention, adhesiveness and peelability, and has no printed image resolution and background stain.

(Means for Solving the Problems) The above object is achieved by the present invention described below. That is,
The present invention relates to a single-sheet composite thermal transfer sheet comprising a heat transfer sheet formed by forming a heat-fusible ink layer on one surface of a base film and a transfer-receiving material in a releasable manner with an adhesive layer. The adhesive layer has a weight ratio of 3 to 5: 1 to 2.5: 3 to
5. A sheet-fed composite thermal transfer sheet, characterized in that the sheet is a pressure-sensitive adhesive, a resin particle, and a wax, and a curl prevention layer is formed on the transfer material.

(Function) By providing a curl prevention layer on the surface of the transfer material and having a specific configuration of the adhesive layer, curl can be prevented irrespective of a change in humidity. It is firmly adhered and has good transportability without wrinkles and deviations, and both are easily peeled off after thermal transfer, the ink layer is accurately transferred to paper in the transfer area, and the transferred area is A sheet-type composite thermal transfer sheet that does not transfer at all and does not contaminate paper is provided.

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

FIG. 1 shows a cross-sectional view of a preferred example of the sheet-type composite thermal transfer sheet of the present invention.

The sheet-type composite thermal transfer sheet of the present invention is a sheet-type composite thermal transfer sheet in which a thermal transfer sheet A and a material to be transferred B are releasably adhered by an adhesive layer C as shown in the drawing. An anti-curl layer D is formed on the surface of the material.

In the thermal transfer sheet A, a heat-fusible ink layer 2 is formed on a base film 1 as shown in the figure.
A mat layer 3 is formed between the base film 1 and the ink layer 2 or a slip layer 4 is formed on the back surface of the base film.

As the base film used in the sheet-type composite thermal transfer sheet of the present invention, the same base film as used in the conventional thermal transfer sheet can be used as it is, and other materials can be used, There is no 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 discoloring by light, heat, temperature or 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. Further, 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 can be mixed with a thermoplastic resin having a relatively low melting point to improve the adhesion of the ink to the material to be transferred.

As a method of forming the hot melt ink layer on the base film, in addition to hot melt coat, hot lacquer coat, gravure coat, gravure reverse coat, roll coat and many other means, the thickness of these ink layers is The thickness may be several μm as in the conventional case.

As the material to be transferred B, high-quality paper, plain paper, synthetic paper, tracing paper, preferably having a stiffness in the range of 10 to 100,
Any sheet or film that can be thermally transferred, such as a plastic film, may be used. If the stiffness is less than the above range, the rigidity of the entire sheet-type composite thermal transfer sheet is insufficient, the waist is weak, and the transfer sheet peels off due to waving or wrinkles, causing a serious problem in transportability. As a result, good printing cannot be performed. On the other hand, if the stiffness exceeds the above range, it becomes uneconomical in terms of the thickness, weight and the like of the sheet-type composite thermal transfer sheet.
In a further preferred embodiment, the surface smoothness of the transferred material is in the range of 10 to 500 seconds, and the basis weight of the transferred material is 30 to 120 seconds.
By setting the ratio in the range of g / m ² , better results can be obtained. The size of the material to be transferred may be a sheet such as an A plate or a B plate, or a continuous sheet having an arbitrary width.

The anti-curl layer D provided on the surface of the base film,
It has a function of reducing the fluctuation of the moisture of the paper as the material to be transferred irrespective of the change of the surrounding humidity.

Preferred embodiments include (1) the case where the anti-curl layer is water-retaining and (2) the case where the anti-curl layer is airtight.

The water-retaining curl preventing layer is formed of a hydrophilic resin liquid such as polyethylene glycol, polypropylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, starch, and cationic starch, and is made of a hydrophobic resin. Even, as described above, hydrophilic resins, relatively low molecular weight mono-polyethylene glycol, mono-polypropylene glycol, glycerin, pentaerythritol, superabsorbent resin, silica gel, highly hydrated inorganic salts, various surfactants, etc. It can be formed by a resin liquid containing a hydrophilic material. Since these layers have high water retention and always adsorb a certain amount of water, it is possible to suppress changes in the water of the transfer material itself even when the humidity of the surrounding environment changes. Can be prevented from curling.

The airtight anti-curl layer is formed from various hydrophobic resin liquids such as polyester resin, acrylic resin, polyurethane resin, polyamide resin, polyvinyl acetate resin, polyvinyl chloride resin, and binders for various printing inks. . These layers have high airtightness, so that even if the humidity of the surrounding environment changes, the change in the water content of the transfer-receiving material can be effectively suppressed, and similarly, the curl of the composite thermal transfer sheet can be prevented.

The curl prevention layer as described above is easily formed by a known coating method, and can be formed on the surface of the material to be transferred before or after lamination with the thermal transfer sheet. The thickness of these layers is 0.
About 5 to 5 μm has a sufficient effect.

The adhesive layer C for temporarily bonding the thermal transfer sheet A and the material to be transferred B includes pressure-sensitive adhesive particles having a low glass transition temperature, resin particles having a high glass transition temperature, and wax particles.

The glass transition temperature of the adhesive is preferably in the range of -90 ° C to -60 ° C. Examples of such an adhesive include a rubber-based adhesive, an acrylic-based adhesive, and a silicone-based adhesive. The form is a solvent solution type, an aqueous solution type, a hot melt type, an aqueous or oily emulsion type, and any of them can be used in the present invention. 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.

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 may be thermosetting resin particles in some cases.

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 above-mentioned adhesiveness, resin particles and wax is 3 to 5:
1 to 2.5: 3 to 5. Outside 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 adhesiveness is used as an aqueous emulsion, the ink layer 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.

The 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. When the film is to be wound, the transfer material may be on the outside or the thermal transfer sheet may be on the outside, and these are cut into single sheets.

The above is the basic structure of the single-wafer composite thermal transfer sheet of the present invention. Of course, as shown in FIG. 1, a slip layer 4 is provided on the back of the thermal transfer sheet to prevent adhesion of the thermal head and improve the slipperiness. Or matte printing by providing a mat layer 3 between the base film and the ink layer,
Any technique known in the field of thermal transfer sheets, such as making the ink layer a hue other than black, can be added to the sheet-fed composite thermal transfer sheet of the present invention.

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) Next, the present invention will be described more specifically with reference to examples and comparative examples. In the description, parts and% are based on weight unless otherwise specified.

Example 1 A 6.0 μm thick polyethylene terephthalate film having a slip layer formed on the back surface was used as a base film, and the surface of the base film was coated with the following ink composition at a rate of 4 g / m ² to form an ink. A 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 Was coated by a gravure coating method at a rate of 0.5 g / m ² when dried, and then a 1 μm-thick anti-curl layer was formed from an aqueous solution of polyethylene glycol on the back side of plain paper (basis weight 64 g / m ^2). m ² ,
A nip (a nip temperature of 50 ° C. and a nip pressure of 500 Kg) was applied to the nip, and cut into an A4 plate to obtain a single-sheet composite 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 to 10 µm) 10 parts Acrylic resin particle aqueous dispersion (solid content 20
%, Glass transition temperature 85 ° C, particle size 0.2-0.5 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 The same plain paper as in Example 1 having a curl preventing layer shown in Table 1 below was used as a material to be transferred. Using the same respective dispersions as in Example 1, the composition (weight ratio) of the temporary mounting agent was changed as shown in Table 2 below, and the other conditions were the same as in Example 1 to obtain a single-leaf composite thermal transfer sheet of the present invention. .

Comparative Example 1 A single-sheet composite thermal transfer sheet of Comparative Example was obtained in the same manner as in Example 1 except that the same plain paper having no curl preventing layer was used as the material to be transferred in Example 1.

The sheet-type composite thermal transfer sheets of the above Examples and Comparative Examples were
℃, 15% RH atmosphere for 30 minutes, 25 ℃, 90% RH
After being left in the atmosphere for 30 minutes, the one of the example curled only slightly, while the one of the comparative example curled remarkably according to the change in humidity.

Further, the adhesive strength between the ink layer and the paper of the sheet-type composite thermal transfer sheets of Examples 1 to 4 was measured, and the results are shown in Table 3. It does not peel off easily even when left, and easily peels off with a fingertip after printing. expressed. From these results, the adhesive strength is 300-1000 g, especially 400
A range of ~ 800 g has been found to be suitable.

The adhesive strength (g) was measured by cutting a sample of 25 mm (width) x 50 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, a curl preventing layer is provided on the surface of a transfer-receiving material, and a specific configuration of an adhesive layer prevents curling irrespective of a change in humidity. In addition, the thermal transfer sheet and the paper are firmly adhered to each other and have good transportability without wrinkles and deviations, and they are easily peeled off after thermal transfer, and the ink layer in the transfer area has a paper layer. The present invention provides a sheet-type composite thermal transfer sheet that transfers images accurately, does not transfer the transfer target area at all, and does not contaminate the paper.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are diagrams schematically illustrating a cross section of a single-wafer composite thermal transfer sheet of the present invention, and FIG. 3 is a schematic diagram illustrating a structure of an adhesive layer. FIG. A: Thermal transfer sheet, B: Transfer material C: Adhesive layer, D: Anti-curl 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

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41M 5/38-5/40

Claims (3)

(57) [Claims] 1. A single-sheet composite thermal transfer sheet comprising a heat transfer sheet having a heat-fusible ink layer formed on one surface of a substrate film and a transfer-receiving material, which are releasably bonded by an adhesive layer. The adhesive layer has a weight ratio of 3 to 5: 1 to 2.5: 3.
5. A sheet-type composite thermal transfer sheet comprising an adhesive, a resin particle and a wax, wherein the anti-curl layer is formed on the material to be transferred. 2. The single-sheet composite thermal transfer sheet according to claim 1, wherein the anti-curl layer is water-retentive. 3. The sheet-type composite thermal transfer sheet according to claim 1, wherein the curl prevention layer is airtight.