JP3031432B2 - Thermal transfer sheet - Google Patents

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 novel co-winding thermal transfer sheet in which a thermal transfer sheet and a material to be transferred, such as paper, are temporarily bonded in advance.

[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 provided with a heat-meltable ink layer on one surface of a base film has been used. This conventional thermal transfer sheet is used as a substrate film such as a capacitor paper or a paraffin paper having a thickness of 10 to 20 μm or a thickness of 3 to 20 μm.
It is manufactured by using a plastic film such as polyester or cellophane having a thickness of μm, and coating a hot-melt ink layer obtained by mixing a coloring agent such as a pigment or a dye with wax. 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, these thermal transfer sheets, for example,
Even if it is diverted to a facsimile printer using conventional thermosensitive coloring paper, the above facsimile printer,
Since the recording paper itself develops heat, it cannot be diverted because there is no transfer device for the material to be transferred.
The same applies to a special printer. As a method for solving the above problems, the thermal transfer sheet and the material to be transferred are preliminarily bonded to each other and wound in a roll shape so as to be adapted to a facsimile printer or the like, and to simplify and reduce the size of the apparatus. A method has been devised.

[0003]

In the case of such a co-winding thermal transfer sheet, the thermal transfer sheet and the paper are firmly adhered to each other so that no wrinkles or deviations occur in the thermal transfer sheet. It is required that the ink layer be easily peeled off and that the ink layer be accurately transferred to the paper in the transfer area, and that the paper be not contaminated at all in the transfer area and 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. Therefore, the object of the present invention is
An object of the present invention is to provide a co-winding thermal transfer sheet which is excellent in both adhesiveness and releasability, has no problem in resolution of a printed image, and has no background stain.

[0004]

The above object is achieved by the present invention described below. That is, the present invention relates to 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 are releasably adhered by an adhesive layer. Contains α-olefin-maleic anhydride copolymer as an essential component
And the adhesive layer is an acrylic tacky resin (a)
And wax (b), and the weight ratio of both is a: b =
1: a thermal transfer sheet characterized by a ratio of 0.5 to 4 .

[0005]

The ink layer contains an α-olefin-maleic anhydride copolymer , and the adhesive layer has an acrylic adhesive.
Resin (a) and wax (b), weight ratio of both
Is set to a: b = 1: 0.5 to 4, it is possible to provide a co-wound thermal transfer sheet which is excellent in both adhesiveness and releasability, and has no printed image resolution and no background stain.

[0006]

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. The thermal transfer sheet of the present invention is a 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, wherein the ink layer of the thermal transfer sheet is an α-olefin-
Contains a maleic anhydride copolymer as an essential component , and
The adhesive layer is made of an acrylic adhesive resin (a) and a wax.
(B), and the weight ratio of both is a: b = 1: 0.5
-4 . Thermal transfer sheet A
As shown in the figure, a hot-melt ink layer 2 is formed on a base film 1.
Is formed, and if necessary, the base film 1 and the ink layer 2
And a slip layer 4 on the back surface.

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. Not restricted. 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. Paper, such as plastic, condenser paper, paraffin paper, and non-woven fabric, and a base film in which these are combined. The thickness of the base film can be appropriately changed depending on the material so that the strength and the thermal conductivity become appropriate, but the thickness is preferably, for example, 2 to 25 μm.

The hot-melt ink layer provided on the base film comprises a colorant and a binder containing an α-olefin-maleic anhydride copolymer as an essential component, and further contains various additives as necessary. It may be added. As this coloring agent, among organic or inorganic pigments or dyes,
It is preferable that the recording material has good characteristics, for example, a material that has a sufficient coloring density and does not discolor by light, heat, temperature, or the like. 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. The α-olefin-maleic anhydride copolymer as an essential component of the binder is a hard wax having a high polarity and a high melting point and a low penetration, and has a dispersing ability for various pigments such as carbon black and ceramics, and a dye dissolving power. It has excellent thermal properties such as low heat of fusion and is suitable for applications such as thermal transfer ink bases and carbon paper. In addition to the α-olefin-maleic anhydride copolymer, other waxes, drying oils, resins, mineral oils, derivatives of cellulose and rubber, and the like can be included. When other binders are used in combination with the α-olefin-maleic anhydride copolymer, the α-olefin-maleic anhydride copolymer preferably accounts for 5% by weight or more of all binders, If so, the operation and effect of the present invention are insufficient.

Representative examples of the wax used in combination 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. 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. 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 transfer material B, ordinary high-quality paper, plain paper, synthetic paper, tracing paper, plastic film, etc.
Any sheet or film that can be thermally transferred 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 used for forming the adhesive layer C for temporarily adhering the thermal transfer sheet A and the material B to be transferred is an acrylic agent that does not transfer the ink layer to the material B when the two are peeled off.
That use Le-based adhesive resin. One example of a preferable pressure-sensitive adhesive is a pressure-sensitive adhesive resin having a low glass transition temperature (or a particle thereof).
And wax. The glass transition temperature of such an adhesive resin is preferably in the range of -90C to -60C ,
Shape condition manner in a solvent solution type, aqueous solution type, hot melt type, there is an aqueous or oily emulsion type, both Ru can be used in the present invention. When the above-mentioned adhesive resin is used alone, excellent adhesiveness can be obtained, but the peelability of the transferred material is insufficient and non-uniform, and the production, storage, transportation, etc.,
If an unexpected force is applied before the thermal transfer, the ink layer of the thermal transfer sheet may be transferred to the material to be transferred, causing a background stain. In addition, during the thermal transfer, the ink layer may be poorly cut out of the foil. For example, the ink layer may be transferred to the periphery of the area to which heat is applied by the thermal head, and the resolution of the transferred image may be poor.

In the present invention, the above problem can be solved by adding a wax emulsion such as that used for forming the ink layer to the above emulsion tacky resin so that the tackiness can be adjusted to a preferable range. Were found to be solved, the breakage of the foil of the adhesive layer C was improved, and the resolution of the transferred image was significantly improved. The weight ratio of the adhesive resin (a) to the wax (b) is a: b = 1: 0.5 to 1: 4.
And Outside of this range, various problems as described above are likely to occur, which is not preferable. Further, by adding a resin emulsion having a higher glass transition temperature to the emulsion of the adhesive resin, the adhesiveness can be easily adjusted to a preferable range. Examples of such a resin emulsion include ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, polyethylene, polystyrene, polypropylene, polybutene, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, and acrylic resin. And the like, and particularly, an acrylic emulsion. Such a resin preferably has a higher glass transition temperature than the adhesive resin, for example, a glass transition temperature of 60 ° C. or higher, and may be a thermosetting resin in some cases.

When the resin particles having a high glass transition temperature are used, the weight ratio of the pressure-sensitive adhesive, the resin particles and the wax is preferably from 3 to 5: 1 to 2.5: 3 to 5.
The adhesive strength (g) of the adhesive layer formed as described above is 2
Cut out a sample of 5 mm (width) x 55 mm (length), and measure it with a surface friction meter (HEIDON-14, manufactured by Shinto Kagaku).
800 mm / min. 8 when measured at a pulling speed of
The range of 00 to 2000 g is preferred.

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. On the other hand, if the adhesive strength exceeds the above range, the adhesive strength is sufficient, but the ink layer is easily transferred to the material to be transferred even in the non-printed area, and the material to be transferred is contaminated. However, if the amount of the thermoplastic resin in the ink layer is, for example, an ethylene-vinyl acetate copolymer having a vinyl acetate content of 28% and the solid content in the ink layer is 9% by weight or more, the base film may be removed. Since the adhesiveness to the ink layer becomes higher, a thermal transfer sheet that does not cause contamination of the transfer material can be obtained even when the adhesive force of the adhesive layer to the transfer material is in the range of 1300 to 2000 g. 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 is 0.1 to 20 μm
A thickness of 0.1 to 5 g / m ² (as a solid coating amount) is preferable.

The adhesion between the thermal transfer sheet A and the transfer material B is
Preferably, the transfer material is continuously adhered while forming an adhesive layer on the surface of the ink layer of the thermal transfer sheet, and the transfer material is wound up in a roll shape. Alternatively, the thermal transfer sheet may be on the outside,
Further, 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, a 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. By providing a release layer 3 between the base film and the ink layer, thermal transfer, such as improving the release of the ink layer and functioning as a protective layer of the printed image after transfer, and changing the ink layer to a hue other than black, etc. Any of the techniques well known in the sheet art can be added to the 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. Is formed.

[0015]

The present invention will be described more specifically below with reference to examples and comparative examples. In the following description, parts and% are based on weight unless otherwise specified. Example 1 A 6.0 μm-thick polyethylene terephthalate film having a slip layer on the back surface was used as a base film, and one of the surfaces 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 10 parts ethylene / vinyl acetate copolymer 14 parts α-olefin-maleic anhydride copolymer 7 parts paraffin wax 60 parts oxidized wax 15 parts (prepared by kneading at 120 ° C for 4 hours with an attritor) ) Further, a temporary adhesive having the following composition was applied onto the above ink layer by a gravure coating method at a ratio of a coating amount at the time of drying of 0.5 g / m ² , followed by plain paper (basis weight 64 g / m ² , Beck surface smoothness 1
40 sec. ) (Nip temperature: 50 ° C., nip pressure: 5 kg / cm ² ) to obtain a thermal transfer sheet of the present invention. Temporary adhesive composition Acrylic adhesive resin dispersion (solid content 40%, Tg = -58 ° C) 10 parts Carnauba wax aqueous dispersion (solid content 40%, melting point 83 ° C) 15 parts Water 10 parts Isopropanol 20 parts

Examples 2 to 4 The thermal transfer sheet of the present invention was obtained in the same manner as in Example 1 except that the amount of the α-olefin-maleic anhydride copolymer in Example 1 was changed as follows. Example 2: Amount of α-olefin-maleic anhydride copolymer 10 parts Example 3: Amount of α-olefin-maleic anhydride copolymer 20 parts Example 4: α-olefin-maleic anhydride copolymer Example 5 A 6.0 μm thick polyethylene terephthalate film provided with a slip layer on the back surface was used as a base film, and the ratio of the ink composition described below was 3 g / m ^{2 on} one surface. To form an ink layer. Ink composition : carbon black 13 parts ethylene / vinyl acetate copolymer 14 parts paraffin wax 60 parts α-olefin-maleic anhydride copolymer 10 parts oxidized wax 15 parts (prepared by kneading at 120 ° C for 4 hours with an attritor) ) Further, a temporary adhesive having the following composition was applied onto the above ink layer by a gravure coating method at a ratio of a coating amount at the time of drying of 0.5 g / m ² , followed by plain paper (basis weight 64 g / m ² , Beck surface smoothness 3
50 sec. ) (Nip temperature: 40 ° C., nip pressure: 5 kg / cm ² ) 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 to 10 µm) 10 parts Acrylic resin particle water-based dispersion (solid content 20%, glass transition temperature) 85 ° C, particle size 0.2-0.3 µm) 15 parts Carnauba wax aqueous dispersion (solid content 40%, melting point 83 ° C) 15 parts Water 10 parts Isopropanol 30 parts

Examples 6 to 8 The thermal transfer sheet of the present invention was obtained in the same manner as in Example 1 except that the amount of the α-olefin-maleic anhydride copolymer in Example 5 was changed as follows. Example 6: Amount of α-olefin-maleic anhydride copolymer 5 parts Example 7: Amount of α-olefin-maleic anhydride copolymer 20 parts Example 8: α-olefin-maleic anhydride copolymer Comparative Example 1 A thermal transfer sheet of a comparative example was obtained in the same manner as in Example 1 except that polyvinyl alcohol was used as an adhesive and an α-olefin-maleic anhydride copolymer was not used. Comparative Example 2 A thermal transfer sheet of a comparative example was obtained in the same manner as in Example 1 except that a polyurethane-based adhesive was used as an adhesive and an α-olefin-maleic anhydride copolymer was not used. The adhesive strength between the ink layer and the paper of the thermal transfer sheet of the above example was not easily peeled even after being left, but was easily peeled off with a fingertip after printing, and the paper had no background stain. On the other hand, in the case of the comparative example, when the paper was peeled after being left, a small amount of background stain on the paper was confirmed.

[0018]

According to the present invention as described above, by including an α-olefin-maleic anhydride copolymer in the ink layer, both the adhesiveness and the releasability are excellent, the resolution of the printed image and the background smear are improved. Can be provided. Further, in a preferred embodiment, by forming the adhesive layer with an adhesive having a specific composition, the thermal transfer sheet and the paper are firmly adhered to each other so that wrinkles and deviations do not occur, and both are easy after thermal transfer. In the transfer area, the ink layer is accurately transferred to the paper, and the non-transfer area does not transfer at all, thereby providing a thermal transfer sheet that does not contaminate the paper.

[Brief description of the 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 the thermal transfer sheet of the present invention.

[Explanation of symbols]

 A: Thermal transfer sheet B: Transfer material C: Adhesive layer 1: Base film 2: Ink layer 3: Release layer 4: Slip layer 5: Thermal head 6: Image

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B41M 5/38-5/40

Claims (1)

(57) [Claims] 1. A 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 material, which are releasably adhered by an adhesive layer. the adhesive layer contains an α-olefin-maleic anhydride copolymer as an essential component , and
Contains a cryl-based adhesive resin (a) and wax (b)
A thermal transfer sheet wherein the weight ratio of the two is a: b = 1: 0.5 to 4 .