JP2958063B2 - Thermal transfer sheet - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an improvement in a thermal transfer sheet, and more particularly, to a novel thermal transfer sheet capable of clear green printing.

(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.

Most of these conventional thermal transfer sheets are for printing using a black pigment, but some of them use a yellow, cyan or magenta pigment for a color image. Further, when printing other than these hues is required, these colors are combined. For example, when green printing is required, yellow and cyan thermal transfer sheets are combined.

However, clear green printing is difficult by such color synthesis, and a thermal transfer sheet capable of clear green printing is required. Of course, it is conceivable to prepare a thermal transfer sheet using a green pigment for green printing, but most of the conventional green pigments are difficult to finely disperse in wax or thermoplastic resin forming an ink layer, and are excellent. There was a problem that green printing having sharpness and density could not be performed.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide a thermal transfer sheet capable of performing clear green printing.

(Means for Solving the Problems) The above object is achieved by the present invention described below. That is,
The present invention is characterized in that a pigment in the ink layer is a copper phthalocyanine green having 14 or more chlorine atoms or bromine atoms in a thermal transfer sheet having a heat-fusible ink layer formed on one surface of a substrate film. Is a thermal transfer sheet.

(Function) By using copper phthalocyanine green having 14 or more chlorine atoms or bromine atoms as a pigment, it is possible to provide a thermal transfer sheet capable of performing clear and high-density green printing.

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

As the substrate film used in 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. Paper, such as plastic film, condenser paper, paraffin paper, and non-woven fabric.
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 formed on one surface of the base film is composed of copper phthalocyanine green having a chlorine number or bromine number of 14 or more and a vehicle, and various additives can be further added as necessary. .

Copper phthalocyanine green having a chlorine number or bromine number of 14 or more used in the present invention is finely dispersed in wax, excellent in heat stability, weather resistance, etc., and various grades are available from the market. Can be used. It is generally preferred that the amount of the copper phthalocyanine green having 14 or more chlorine atoms or bromines be about 5 to 50% by weight in the ink.

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 such a thermoplastic resin, for example, an ethylene-vinyl acetate copolymer (EV
A), ethylene-acrylate copolymer (EEA),
Polyethylene, polystyrene, polypropylene, polybutene, petroleum resin, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol, vinylidene chloride resin, methacrylic resin, polyamide, polycarbonate, fluororesin, polyvinyl formal, polyvinyl butyral, acetyl cellulose , Nitrocellulose,
Polyvinyl acetate, polyisobutylene, ethyl cellulose or polyacetal or the like is used, particularly a relatively low softening point conventionally used as a heat-sensitive adhesive, for example, 50 to 80
Those having a softening point of ° C are preferred. The use ratio of the wax to the thermoplastic resin is preferably in a weight ratio of the thermoplastic resin to wax 100 to 5 to 300.

As a method of applying the hot melt ink on the base film, a hot lacquer coat,
A gravure coat, a gravure reverse coat, a roll coat, and many other means are included.

The thickness of the ink layer is about 0.5 to 5 μm in the case of a thermal transfer sheet for one-time printing, and is about 5 to 15 μm in the case of multi-time printing or N-times mode printing.

In the present invention, a surface layer may be formed from the uncolored wax on the ink layer, and the surface layer can further effectively prevent the transfer material from being stained during printing.

The surface layer formed as described above preferably has a thickness of 0.1 μm or more and 5 μm so that the sensitivity does not become insufficient even when the printing energy is low like a high-speed linter.
m. If the thickness is less than 0.1 μm, the paper to be transferred and the ink layer may be rubbed to cause background contamination. The surface layer is substantially colorless after thermal transfer, and may be colored white by adding an appropriate amount of extender or white pigment.

When a material weak to heat is used for the base film, it is preferable to provide a layer for preventing sticking of the thermal head on the surface in contact with the thermal head. The sticking prevention layer has a heat-resistant resin and a substance acting as a heat release agent or a lubricant as basic constituent components. As the heat-resistant resin, a compound having two or more amino groups or a diisocyanate or a triisocyanate is added to a synthetic resin having a glass transition point of 60 ° C. or higher or a thermoplastic resin having an OH group or a COOH group, and the resin is slightly cross-linked and cured. Are preferred. Thermal release agents or lubricants are those that melt and act upon heating, such as amides, esters, and salts of waxes and higher fatty acids, and those that remain fixed, such as powders of fluororesins and inorganic substances. There is.

By providing such an anti-sticking layer, thermal printing can be performed without sticking even on a thermal transfer sheet based on a heat-sensitive plastic film, making the plastic film difficult to cut and easy to process. You can take advantage of such advantages.

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 polyethylene terephthalate film having a thickness of 6.0 μm was used as a base film, and a hot-melt ink composed of the following components was kneaded on one surface at 120 ° C. for 6 hours. It was applied at a rate of 3 g / m ² (dry state) by a melt roll coating method to obtain a thermal transfer sheet of the present invention.

Hot melt ink Copper phthalocyanine green with 16 chlorine atoms 15 parts Ethylene / vinyl acetate copolymer (EVA Flex 310, manufactured by Mitsui Polychemicals) 8 parts Paraffin washes (paraffin 150F, manufactured by Nippon Seiro) 50 parts Carnauba wax 25 Part Example 2 A thermal transfer sheet of the present invention was obtained in the same manner as in Example 1, except that copper phthalocyanine green having 15 bromine was used instead of copper phthalocyanine green having 16 chlorine.

Comparative Example 1 A thermal transfer sheet of Comparative Example was prepared in the same manner as in Example 1 except that a green pigment composed of a mixture of a yellow azo pigment and a copper phthalocyanine blue pigment was used instead of copper phthalocyanine green having 16 chlorine atoms in Example 1. I got

Use Example 1 Using the thermal transfer sheets of Examples 1 and 2 and Comparative Example 1, printing was performed under the following printing conditions, the printing quality was examined, and the results shown in Table 1 were obtained.

Printing conditions Applicable equipment: Line-type printer equipped with a thin-film thermal head (10dot / mm) Printing energy: 0.4mJ / dot (constant) Transfer object: Plain paper Evaluation Criteria Sharpness: Observed with the naked eye, and particularly excellent was evaluated as ◎, and slightly inferior was evaluated as Δ.

Image density: A particularly excellent product was evaluated as ◎, and a product poor in poor dispersion was evaluated as ×.

(Effect) According to the present invention as described above, by using copper phthalocyanine green having 14 or more chlorine atoms or bromine atoms as a pigment, it is possible to provide a thermal transfer sheet capable of clear green printing.

Continuation of the front page (56) References JP-A-63-13782 (JP, A) JP-A-3-79683 (JP, A) JP-A-3-180384 (JP, A) JP-A-63-312364 (JP) , A) JP-A-2-243377 (JP, A) JP-A-64-30788 (JP, A) Edited by The Japan Society of Colorants, New Color Science Handbook, University of Tokyo Press, February 25, 1980, first edition, P691-699 (58) Field surveyed (Int. Cl. ⁶ , DB name) B41M 5/38-5/40

Claims (1)

(57) [Claims] 1. A thermal transfer sheet having a heat-meltable ink layer formed on one surface of a base film, wherein the pigment in the ink layer is copper phthalocyanine green having 14 or more chlorine atoms or bromine atoms. Characteristic thermal transfer sheet.