JPH0577568A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE:To provide a thermal transfer sheet imparting printing having durability such as excellent abrasion resistance, heat resistance, etc. CONSTITUTION:In a thermal transfer sheet, in which an ink layer 3 is formed on one surface of a base material film 1 through a peel ply 2 composed of wax, the ink layer 3 is formed of a resin not melted by heat by a thermal head 4.

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 thermal transfer sheet which gives printing having excellent abrasion resistance, solvent resistance, heat resistance and the like.

[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.

[0003]

These known thermal transfer sheets are image-wise heated from the back by a thermal head to melt the ink layer, and the adhesiveness of the ink layer generated at that time causes an image to be transferred onto the transfer material. Therefore, the ink layer is formed of a material having a low melting point. Therefore, the image of the transferred product has low abrasion resistance, solvent resistance, heat resistance, etc., and the image is easily worn, peeled off, or streaked due to friction to contaminate the white area around the printed area. There is. Such problems are caused by excellent abrasion resistance such as price tags, tag labels such as size and bar code labels,
This is a serious problem in fields requiring durability such as solvent resistance and heat resistance. For example, there are many opportunities for products to come into contact with each other, such as in automobile factories and other mechanical parts factories,
Barcodes using conventional thermal transfer cannot be used in locations where mechanical oil is present or where high temperatures are likely to occur. As a method of solving these problems, a transparent cover film such as a thin polyester film is laminated on the surface of a printed bar code label to form a surface protective layer. According to this method, a barcode label excellent in abrasion resistance and the like is produced, but since it is necessary to provide a film laminator in the barcode printer and the printer becomes large-scale, it is not suitable for small-lot production. There is a problem. Therefore, it is an object of the present invention to provide a thermal transfer sheet which solves the above-mentioned problems of the prior art and gives a print having excellent durability such as abrasion resistance and heat resistance.

[0004]

The above object can be achieved by the present invention described below. That is, the present invention is a thermal transfer sheet in which an ink layer is provided on one surface of a substrate film via a release layer made of wax, wherein the ink layer is formed of a resin that is not melted by heat from a thermal head. Is a thermal transfer sheet.

[0005]

The ink layer of the thermal transfer sheet is formed of a resin that is not melted by the heat of the thermal head through a release layer made of wax, and the ink is formed by some method, for example, by providing a heat-sensitive adhesive layer on the surface of the ink layer. Thermal transferability can be imparted to the layer, and printing that is excellent in durability such as abrasion resistance, solvent resistance, and heat resistance and that does not cause scumming is possible.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the drawings showing the preferred embodiments. FIG. 1 is a diagram schematically showing a cross section of a thermal transfer sheet of the present invention and a state of thermal transfer. The thermal transfer sheet of the present invention has a thermal head with a release layer 2 made of wax on one surface of a base film 1. It is characterized in that the ink layer 3 made of a resin that is not melted by the heat of 4 is provided. As the base film used in the present invention, the same base film as that used in the conventional thermal transfer sheet can be used as it is, and other films can also be used and are not particularly limited. Specific examples of the preferable substrate film, for example, polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride, polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin,
There are plastics such as chlorinated rubber and ionomer, papers such as condenser paper and paraffin paper, non-woven fabrics, and the like, and a base film in which these are compounded 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 thereof are appropriate, but the thickness is, for example, preferably 2 to 25 μm.

The peeling layer 7 made of wax formed on one surface of the base film is melted during thermal transfer to improve the peelability of the ink layer, and after transfer, at least a part of the ink layer is formed on the surface of the transferred image. It is transferred together with the protective layer of the ink layer, particularly, imparts good slipperiness to the transferred image, and improves the scratch resistance of the transferred image. In the present invention, first, the release layer 2 is formed on the surface of the base film 1. For the release layer 2, for example, acrylic resin, silicone resin, fluororesin, silicone, or various resins modified with fluorine, which have excellent releasability, can be used, but wax is preferable. As such a wax, various waxes that melt and exhibit peelability during printing are preferable. Suitable waxes include, for example, microcrystalline wax, carnauba wax, paraffin wax, Fischer-Tropsch wax, various low molecular weight polyethylene, wood wax, beeswax, spermaceti wax, ivowa wax, wool wax, shellac wax, candelilla wax. , Various waxes such as petrolactam, partially modified wax, fatty acid ester, and fatty acid amide. Particularly preferred waxes are microcrystalline wax, carnauba wax, etc., which have a relatively high melting point and are difficult to dissolve in a solvent. The release layer 2 is preferably a thin layer, for example, a thickness of about 0.1 to 2 μm so as not to reduce the sensitivity of the thermal transfer sheet.

Ink layer 3 formed on the surface of the release layer 2
Is not formed from a conventional wax ink, but is formed from an ink containing a resin that does not melt by heat as a binder. Particularly preferred ink is a resin such as that used in conventional gravure ink as a resin binder, for example,
Natural resins such as shellac, rosin, rosin-modified maleic acid, nitrification cotton, cellulose acetate, polyamide, chlorinated rubber, chlorinated polymethylpentene, cyclized rubber and their derivatives, polyvinyl chloride, ethylene-vinyl acetate copolymer,
Synthetic resin such as polypropylene chloride, acrylic resin, urethane resin, isocyanate resin is used. When these resin binders alone are melted by heat, a curing agent may be added to the ink to crosslink and cure the resin binder. In this case, it is preferable that the resin binder has a reactive group such as a hydroxyl group, a carboxyl group, an amino group, and an isocyanate group. Further, even if it does not have such a reactive group, the curing agent itself may be crosslinked to solidify the resin binder to form an ink layer which is not melted by heat.

A pigment such as carbon black is used as a colorant to be added to the binder, and an alcohol solvent such as methanol, ethanol, IPA, n-butanol, methyl acetate, ethyl acetate, n-butyl acetate, etc. is used as a solvent. Ester solvents, acetone, MEK, MIBK,
A ketone solvent such as cyclohexanone, an alcohol derivative such as methyl cellosolve, ethyl cellosolve and butyl cellosolve, an aromatic solvent such as benzol, toluene and xylol, and an aliphatic solvent such as n-hexane and cyclohexane are used. Further, as additives, for example, phthalate ester-based, fatty acid ester-based, phosphate ester, epoxy-based plasticizers, metal soap-based, phenol-based,
Antioxidants such as sulfide-based and phosphite-based, UV absorbers such as benzophenone-based, triazole-based, acrylate-based, paraffin wax, hydrocarbon-based, fatty acid and its amide-based, ester-based, alcohol-based lubricants, alcohol-based , Fatty acid and its ester type, amide type, phosphate ester, silicone oil type antifoaming agent, anionic type, cationic type, nonionic type, antistatic agent such as amphoteric activator, etc. are added as necessary Be done. Further, in order to improve the cutting of the ink layer at the time of thermal transfer, inorganic particles such as silica, alumina and clay and organic particles such as plastic pigments can be added.

However, if the ink layer 3 to be formed is too thick, the ink film is not easily cut during thermal transfer. Therefore, the thickness of the ink layer is preferably about 0.1 to 5 μm. When the resin as described above is used, the pigment is sufficiently dispersed, so that it is possible to obtain a sufficient coloring density even if the ink film thickness is thin. Examples of the method for forming the ink layer 3 include gravure coating, gravure reverse coating, roll coating, and other methods of coating and drying and curing the ink, and the coating method is not particularly limited. As shown in FIG. 1, the transfer method using the thermal transfer sheet is performed by superposing the thermal transfer sheet on a transfer target material 7 having a heat-sensitive adhesive layer 5 on the surface, and heating the image transfer image from the back side by the thermal head 4. As a result of the heat-sensitive adhesive layer 5 exhibiting adhesiveness and the ink layer 3 being easily broken by heat, the ink image 6 is transferred to the heat-sensitive adhesive layer 5. As described above, in the present invention, the ink layer 3 does not melt during thermal transfer, but it is easily transferred due to the presence of the heat-sensitive adhesive layer 5. Since the ink image 6 thus transferred is not composed of a wax having a low melting point but a resin having a high softening point or an infusible crosslinked resin, it has excellent abrasion resistance, solvent resistance, and It has robustness such as water resistance and heat resistance, so it rubs, solvents, water,
It does not contaminate the white background around the printing area due to heat or the like.

Further, since the heat-sensitive adhesive layer 5 is present on the surface of the printed matter formed as described above, it is possible to easily laminate a cover film such as a transparent film on the entire surface thereof. As the transfer material used in the above, as long as it has a heat-sensitive adhesive layer on the surface, any material such as general paper, bar code label paper, synthetic paper, plastic film, sheet, metal, wood, glass, resin molded product, etc. However, it is not particularly limited. In a preferred embodiment of the present invention, a heat-sensitive adhesive layer 5 is formed on the surface of the ink layer 3 as shown in FIG. When the adhesive layer is not formed, the ink layer 3 is not transferred as it is. Therefore, for example, as described with reference to FIG. 1, a means such as forming the heat-sensitive adhesive layer 5 on the transfer material 7 is used. However, by forming the adhesive layer 5 on the surface of the ink layer 3 in advance as shown in FIG. 2, it is possible to obtain a good transfer property to any transfer target material 7 having no adhesive layer. I will have it.

The heat-sensitive adhesive layer 5 provided on the surface of the ink layer 3 is the same as the adhesive layer provided on the transfer material 7 described with reference to FIG. 1, and is softened at a temperature of about 50 to 200 ° C. Is a thermoplastic resin that exhibits adhesiveness, for example, ethylene-vinyl acetate copolymer (EVA), ethylene-
Acrylic ester copolymer (EEA), polyester resin, polyethylene, polystyrene, polypropylene, polybutene, petroleum resin, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol, vinylidene chloride resin, methacrylic resin, polyamide, polycarbonate , Polyvinyl formal, polyvinyl butyral, acetyl cellulose, nitrocellulose, polyvinyl acetate, polyisobutylene, ethyl cellulose, polyacetal, and the like, and particularly a relatively low softening point conventionally used as a heat-sensitive adhesive, for example, 50 to 150. ℃
Those having a softening point of are preferable.

The layer 5 composed of these heat-sensitive adhesives can be formed by hot-melt coating the above-mentioned adhesive resin or by coating and drying a coating solution prepared by dissolving or dispersing it in an appropriate organic solvent or water, The preferable thickness is about 1 to 20 μm. These heat-sensitive adhesive layers 5 may be transparent or colored. The above heat-sensitive adhesive layer 5 contains waxes, amides, esters and salts of higher fatty acids, powders of fluororesins and inorganic substances in order to prevent blocking when the resulting thermal transfer sheet is wound into a roll. An antiblocking agent can be added as described above. Further, these antiblocking agents can also prevent the adhesion between the thermal transfer sheet and the material to be transferred during thermal transfer. Further, in the present invention, it is also preferable to form a back surface layer 8 on the back surface of the substrate film 1 to prevent the thermal head from sticking to improve the running property of the head and to prevent charging. In addition, while the thermal transfer image is generally glossy and beautiful on the print,
Matte printing may be desirable because it can make the document difficult to read. In such a case, for example, a base film is coated with an inorganic pigment such as silica or calcium carbonate dispersed in an appropriate solvent to form a mat layer (not shown), and the ink is added. A layer may be formed, or the base film itself may be matted and used.

The transfer method using the thermal transfer sheet shown in FIG. 2 is the same as the general thermal transfer method, and for the same reason as in the case of FIG. 1, it is very excellent in abrasion resistance, solvent resistance, water resistance and the like. Therefore, it is possible to provide printing that does not contaminate the white background around the printing portion due to scratching and the like. Needless to say, the present invention can be applied to a thermal transfer sheet for color printing, so that a multicolor thermal transfer sheet is also included in the scope of the present invention.

[0015]

EXAMPLES Next, the present invention will be described more specifically with reference to examples. In the text, “part” or “%” is based on weight unless otherwise specified. Example 1 A 6 μm-thick polyester film having an anti-adhesion layer formed on the back surface was coated with a release layer coating solution having the following composition at a rate of 0.5 g / m ^{2 based} on solid content and dried. ,
Next, an ink having the following composition is applied to the surface of the release layer by a gravure reverse method at a rate of 0.7 g / m ^{2 based on} the solid content and dried, and a coating liquid for an adhesive layer having the following composition is solidified on the surface. A thermal transfer sheet of the present invention was prepared by coating and drying at a rate of 0.8 g / m ^{2 on} a minute basis. Coating solution for release layer Carnauba wax 80 parts Ethylene-vinyl acetate copolymer 20 parts Ink composition Carbon black (Shiast S, Tokai Carbon) 10.0 parts Chlorinated rubber 10.0 parts Chlorinated polymethylpentene (Super Clone 602 , Sanyo Kokusaku Pulp) 11.0 parts Plasticizer (dibutyl adipate DBA, manufactured by Daihachi Chemical Industry) 3.0 parts Polyethylene wax (A wax, manufactured by BASF) 2.0 parts Toluene 60.0 parts n-heptane 4.0 Part Adhesive layer coating liquid Styrene-butadiene rubber (Sorprene 1204, manufactured by Asahi Kasei) 2.4 parts Chlorinated polypropylene (Super Clone 907LL, Sanyo Kokusaku Pulp) 2.0 parts Ethylene / vinyl acetate copolymer (Smitate KC10, Sumitomo Chemical Co., Ltd. 10.0 parts Petroleum resin (Neopolymer 130, Nippon Oil Co., Ltd.) 5.0 parts Microsilica (Erosir OK-412) Degussa) 0.4 parts of polyethylene wax (Microfine 8F gold, manufactured by Goodyear) 1.5 parts amide wax (AP65, manufactured by Denka polymer) 1.5 parts of xylene 80.0 parts

Example 2 A thermal transfer sheet of the present invention was prepared in the same manner as in Example 1 except that the following coating liquid was used in place of each coating liquid in Example 1. Coating solution for release layer Carnauba wax 80 parts Paraffin wax 20 parts Ink composition Carbon black (Shiast S, Tokai Carbon) 10.0 parts Acrylic polyol 10.0 parts Chlorinated polymethylpentene (Super Clone 602, Sanyo Kokusaku Pulp) ) 11.0 parts Plasticizer (dibutyl adipate DBA, manufactured by Daihachi Chemical Industry) 3.0 parts Polyethylene wax 2.0 parts Curing agent (polyisocyanate, manufactured by Morohoshi Ink) 3.0 parts Toluene 60.0 parts n-heptane 4 0.0 parts Adhesive layer coating liquid styrene-butadiene rubber (Sorprene 1204, manufactured by Asahi Kasei) 2.4 parts Chlorinated polypropylene (Super Clone 907LL, Sanyo Kokusaku Pulp) 2.0 parts Ethylene / vinyl acetate copolymer (Smitate) KC10, Sumitomo Chemical Co., Ltd. 10.0 parts Petroleum resin (Neopolymer 130, Nippon Oil Co., Ltd.) 5.0 parts My Roshirika (Aerosil® OK-412, manufactured by Degussa) 0.4 parts of polyethylene wax (Microfine 8F gold, manufactured by Goodyear) 1.5 parts amide wax (AP65, manufactured by Denka polymer) 1.5 parts of xylene 80.0 parts

Example 3 A thermal transfer sheet of the present invention was prepared in the same manner as in Example 1 except that the following coating liquid was used in place of each coating liquid in Example 1. Coating liquid for release layer Carnauba wax 85 parts Microcrystalline wax 15 parts (emulsion coating) Ink composition Carbon black (SEAST S, Tokai Carbon) 10.0 parts Cyclized rubber 10.0 parts Chlorinated polymethylpentene (Super) Clon 602, Sanyo Kokusaku Pulp) 8.0 parts Toluene 72.0 parts Adhesive layer coating liquid Polyester resin (softening point 165 ° C) 10.0 parts Polyethylene wax 5.0 parts Carnauba wax 5.0 parts

Comparative Example 1 A thermal transfer sheet was prepared in the same manner as in Example 2, except that the ink having the following composition was used instead of the ink in Example 2. Ink composition Carbon black (Shiest SO, Tokai Carbon) 20 parts Carnauba wax (manufactured by Nippon Seiro Co., Ltd.) 40 parts Paraffin wax 150 ° F (manufactured by Nippon Seiro Co., Ltd.) 40 parts Performance comparison Next, thermal transfer of the above-mentioned examples and comparative examples. The sheet was used to print a barcode on a barcode sheet with a barcode printer (BC8, manufactured by Autonics). When this bar code label was tested by a bar code label reading / verifying machine, it was found to have very good readability.
Further, the obtained label was also very excellent in durability such as abrasion resistance, oil resistance and heat resistance. When the bar code labels of the thermal transfer sheets of Examples 1 to 3 and Comparative Examples 1 and 2 were tested for abrasion resistance, heat resistance and solvent resistance, the results shown in Table 1 below were obtained.

[0019]

[Table 1] ⊚: No bleeding of print and no background stain. ◯: There is some blurring of printing and background stains. Δ: There are many print bleeds and background stains. X: Unreadable due to large print bleeding, stains and dissolution.

Evaluation conditions Iron: 180 ° C for 3 seconds with a cloth applied, 3.5 Kg /
Heat press at cm ² (air pressure). Eraser: Plastic eraser (dragonfly, PE-04A)
Rub 10 times (load about 500g). IPA: Rub 10 times with gauze impregnated with isopropyl alcohol (made by Nippon Oil Co., Ltd., first grade) (load approx. 200)
g). Kerosene: Rub it 10 times with gauze impregnated with kerosene (load about 200g). Car wax: Rub 5 times with wax (New Hope, using Newclean wax) (load approx. 200 g).

[0021]

As described above, it is clear that the printed image formed by the thermal transfer sheet of the present invention is significantly excellent in abrasion resistance, solvent resistance and heat resistance as compared with the conventional one.

[0022]

[Brief description of drawings]

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

FIG. 2 is a diagram schematically illustrating a thermal transfer sheet and a thermal transfer method according to another embodiment.

[Explanation of symbols]

 1: Substrate film 2: Release layer 3: Ink layer 4: Thermal head 5: Adhesive layer 6: Ink image 7: Transfer material 8: Back layer

Claims (4)

[Claims] 1. A thermal transfer sheet in which an ink layer is provided on one surface of a substrate film via a release layer made of wax, wherein the ink layer is formed of a resin that is not melted by heat from a thermal head. And a thermal transfer sheet. 2. The thermal transfer sheet according to claim 1, wherein a heat-sensitive adhesive layer is formed on the surface of the ink layer. 3. The thermal transfer sheet according to claim 1, wherein the ink layer has a thickness of 0.1 to 5 μm. 4. The thermal transfer sheet according to claim 1, wherein the ink layer is formed by using a resin used for gravure printing ink as a binder.