JPH0480088A - Thermal transfer sheet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to improvements in thermal transfer sheets, and more particularly to a novel thermal transfer sheet capable of printing clear green prints.

(Prior art and its problems) Conventionally, when printing output prints from computers or word processors using a thermal transfer method, a thermal transfer sheet with a heat-melting ink layer provided on one side of a base film has been used. .

This conventional thermal transfer sheet has a thickness of 1 mm as a base film.
Using paper such as capacitor paper or paraffin paper with a thickness of 0 to 20 μm, or plastic film such as polyester or cellophane with a thickness of 3 to 20 μm, a layer of heat-melting ink made by mixing coloring agents such as pigments and dyes with wax is applied. It is manufactured by coating.

Most of these conventional thermal transfer sheets are for printing using black pigments, but some are also known for using yellow, cyan, or mazeta pigments for color images. Further, when printing in hues other than these is required, these colors are synthesized. For example, when green printing is required, color synthesis is performed using yellow and cyan thermal transfer sheets.

However, it is difficult to print a clear green color by such color composition, and a thermal transfer sheet capable of printing a clear green color is required. Of course, it is conceivable to use a green pigment to create a thermal transfer sheet for green printing, but most conventional green pigments are difficult to finely disperse in the wax or thermoplastic resin that forms the ink layer, making it difficult to finely disperse them into the wax or thermoplastic resin that forms the ink layer. There was a problem in that green printing with high clarity and density could not be achieved.

Therefore, it is an object of the present invention to solve the above-mentioned problems of the prior art,
An object of the present invention is to provide a thermal transfer sheet capable of printing clear green characters.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention is a thermal transfer sheet comprising a heat-melting ink layer formed on one surface of a base film, characterized in that the pigment in the ink layer is copper phthalocyanine green.

(Function) By using copper phthalocyanine green as a pigment, it is possible to provide a thermal transfer sheet capable of printing clear and high-density green printing.

(Preferred Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

The base film used in the present invention is not particularly limited, and the same base film used in conventional thermal transfer sheets can be used as is, and other films can also be used.

Specific examples of preferred base films include polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride,
Polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin, chlorinated rubber,
Examples include plastic films such as ionomers, papers such as condenser paper and paraffin paper, nonwoven fabrics, and base films made of composites of these materials.

The thickness of this base film can be changed as appropriate depending on the material so that its strength and thermal conductivity are appropriate, but the thickness is preferably, for example, 2 to 25 μm.

The heat-melting ink layer formed on one side of the base film is made of copper phthalocyanine green and a vehicle, and various additives can be added as necessary.

The copper phthalocyanine green used in the present invention has excellent fine dispersibility in wax, thermal stability, weather resistance, etc., and is available in various grades on the market. In terms of dispersibility, copper phthalocyanine green having 14 or more chlorines or bromines is particularly preferred. It is generally preferred that the copper phthalocyanine green be used in an amount of about 5 to 50% by weight in the ink.

The vehicle used includes wax as a main component, and mixtures of wax with drying oil, resin, mineral oil, cellulose, rubber derivatives, and the like.

Representative examples of wax include microcrystalline wax, carnauba wax, paraffin wax, and the like. In addition, various products such as Fischer-Tropsch wax, various low molecular weight polyethylenes, wood wax, beeswax, spermaceti wax, privet wax, wool wax, shellac wax, candelilla wax, petrolactam, polyester wax, assorted waxes, fatty acid esters, fatty acid amides, etc. Wax is used.

In the present invention, it is also possible to mix a thermoplastic resin with a relatively low melting voice into the wax to improve the adhesion of the ink to the transfer material. Examples of such thermoplastic resin include ethylene-vinyl acetate copolymer (EVA)
, ethylene-acrylic acid ester copolymer (EEA),
Polyethylene, polystyrene 5 polypropylene, bolybdenum, 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, etc., are used, and in particular, those having a relatively low softening point, such as 50 to 8, which are conventionally used as heat-sensitive adhesives.
Those having a softening point of 0°C are preferred. The ratio of the wax to the thermoplastic resin used is preferably within a weight ratio of 5 to 300 parts of the thermoplastic resin to 100 parts of the wax.

Methods for applying the hot melt ink onto the base film include hot melt coating, hot lacquer coating, gravure coating, gravure reverse coating, roll coating, and many other methods.

The thickness of the ink layer is approximately 0.5 to 5 μm in the case of a thermal transfer sheet for one-time printing, and approximately 5 to 15 μm in the case of multiple 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 this surface layer can better prevent scumming on the transfer material during printing.

The thickness of the surface layer formed as described above is preferably 0.1 um or more to prevent insufficient sensitivity even when printing energy is low as in high-speed printers.
I am a μm detective. This thickness is 0. Below lLLm,
There is a risk that the transfer paper and the ink layer will rub against each other, causing background stains. The surface layer is substantially uncolored after thermal transfer,
It may be colored white by adding an appropriate amount of extender pigment or white pigment.

When a heat-sensitive material is used for the base film, it is preferable to provide a layer on the surface in contact with the thermal head to prevent sticking of the thermal head. The anti-sticking layer basically includes a heat-resistant resin and a substance that functions as a heat release agent or a lubricant. Heat-resistant resins include synthetic resins with a glass transition point of 60°C or higher, or thermoplastic resins having OH or COOH groups, and a compound having two or more amino groups, or diisocyanate or triisocyanate added to slightly crosslink and cure. Preferably, those that cause Thermal mold release agents or lubricants include those that melt when heated, such as waxes and amides, esters, and salts of higher fatty acids, and those that act as solids, such as fluororesin and inorganic substance powders. There is.

By providing such a sticking prevention layer,
Thermal printing is possible even on thermal transfer sheets based on heat-sensitive plastic films, without causing sticking, and the advantages of plastic films, such as resistance to cutting and ease of processing, can be utilized.

(Example) Hereinafter, the present invention will be explained in more detail by giving Examples and Comparative Examples. In the text, parts or percentages are based on weight unless otherwise specified.

Example 1 A polyethylene terephthalate film with a thickness of 6.0 μm was used as a base film, and on one side of the base film, a hot-melt ink consisting of the following components was kneaded at 120°C for 6 hours. The thermal transfer sheet of the present invention was obtained by coating at a rate of 3 g/rrl' (dry state) using a hot melt roll coating method.

Copper phthalocyanine green with 16 chlorines 15 parts Ethylene/vinyl acetate copolymer (EVA Flex 31
0, Mitsui Polychemical Fissure) 8 parts paraffin wax (paraffin 150F, manufactured by Hiki Seiro)
50 parts carnauba wax
25 parts 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 bromines was used in place of the copper phthalocyanine green in Example 1.

Comparative Example 1 A thermal transfer sheet of a comparative example was obtained in the same manner as in Example 1 except that a green pigment consisting of a mixture of a yellow azo pigment and a copper phthalocyanine blue pigment was used in place of the copper phthalocyanine green in Example 1.

Use Example 1 Using the thermal transfer sheets of Examples 1 to 2 and Comparative Example 1, printing was carried out under the following printing conditions, and the printing quality was examined to obtain the results shown in Table 1.

Equipment used: Thin film thermal head (10 dots/
Line type printer printing energy + equipped with mm)
0.4 mJ/dot (constant) Transferred object: Plain paper Sharpness: Observed with the naked eye, and those that were particularly excellent were rated OL, those that were slightly inferior were rated △.

Image density: Especially excellent was rated 0, and poor due to poor dispersion was rated x.

(Effects) According to the present invention as described above, by using copper phthalocyanine green as a pigment, it is possible to provide a thermal transfer sheet capable of printing clear green prints.

patent applicant Dai Nippon Printing Co., Ltd.

Claims (2)

[Claims] (1) A thermal transfer sheet comprising a heat-melting ink layer formed on one side of a base film, characterized in that the pigment in the ink layer is copper phthalocyanine green. (2) Copper phthalocyanine green has a chlorine number or bromine number of 1
The thermal transfer sheet according to claim 1, wherein the thermal transfer sheet has four or more copper phthalocyanine greens.