JPH04197792A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE:To eliminate fear about secret leakage from a used thermal transfer sheet by providing a heat-melting ink layer on one end of a base film through a mat layer, and providing this mat layer having the same color as the ink layer and in a patterned fashion. CONSTITUTION:A colored mat layer is formed in a patterned fashion on one surface of a base film. The mat layer is obtained by printing a pattern using ink for mat layer formation consisting of a coloring pigment of the same color as the ink layer and an inorganic pigment as a matting agent dispersed in any appropriate resin solution on the base film. In addition, a heat-melting ink which is composed of a coloring agent and a vehicle and, if necessary, various additives is formed on the surface of the mat layer. The recommended ink layer and mat layer are such as appearing black. Subsequently, void characters on a thermal transfer sheet cannot be interpreted, if the ink layer is transferred, so that no secret leakage occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a thermal transfer sheet, and more specifically, to a new thermal transfer sheet that is free from the risk of leaking confidential information from a used thermal transfer sheet.

(Prior Art) Conventionally, when printing output prints from computers or word processors by a thermal transfer method, a thermal transfer sheet having 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.

When a conventional thermal transfer sheet is used to print onto paper, the ink layer is transferred to the surface of the paper, and the used thermal transfer sheet is discarded in the form of white characters.

(Problem to be solved by the invention) In the above conventional method, there is no problem of confidentiality leakage when creating general documents (particularly non-confidential documents), such as contract documents, patent documents, know-how documents, etc. When creating highly confidential documents such as documents, the content of those documents is recorded as white characters on used thermal transfer sheets, so there is a problem in that sufficient care must be taken when disposing of them. be.

There are methods to solve the above problems, such as coloring the base film, but even then, the ink removal characters can be read due to the difference in density between the areas where the ink has come out and the areas where the ink has not come out, and sufficient confidentiality can be maintained. You can't get sex.

Therefore, an object of the present invention is to provide a thermal transfer sheet that is free from leakage of confidential information from a used thermal transfer sheet.

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

That is, the present invention provides a thermal transfer sheet in which a heat-fusible ink layer is provided on one surface of a base film via a matte layer, and the matte layer has the same hue as the ink layer and is provided in a pattern. This is a thermal transfer sheet characterized by:

(Function) By providing the matte layer with the same hue as the ink layer and in a pattern, even if the ink layer is transferred, the white characters on the used thermal transfer sheet will be unreadable, and the used thermal transfer sheet will not be readable. There is no risk of confidential information being leaked from the sheet.

(Preferred Embodiments) Next, the present invention will be explained in more detail with reference to 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 plastics 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.

In the present invention, a colored matte layer is formed in a pattern on one surface of the base film. This mat layer is
For example, gravure printing is performed on a base film using a matte layer forming ink in which a colored pigment having the same hue as the ink layer and an inorganic pigment as a matting agent, such as silica or calcium carbonate, are dispersed in an appropriate resin solution. Depending on the method etc.
Obtained by printing a pattern. The pattern may be any pattern such as letters, symbols, background patterns, straight lines, curved lines, etc. Alternatively, it may be a black and white reversed image (negative) of the above pattern. The thickness of such a matte layer is preferably about 0.05 to 1.0 μm, for example.

Also, as an example of a pattern, a large number of diagonal lines with a certain width may be provided using ink for the matte layer (in this case,
Since irregularities may occur in the printed matter or the gloss of the printed matter may change locally, clear mud ink may be applied to the entire surface including the pattern to fill in the irregularities. Furthermore, in the present invention, these patterns form a heat-melting ink layer on the surface of the matte layer on the surface of the base film opposite to the matte layer (heat-resistant layer side). The hot-melt ink consists of a colorant and a vehicle, and may further contain various additives as required.

The hot-melt ink used in the present invention comprises a colorant and a vehicle, and may further contain various additives as required.

The coloring agent is preferably an organic or inorganic pigment or dye that has good properties as a recording material, for example, one that has sufficient color density and does not discolor or fade due to light, heat, temperature, etc.

Alternatively, it may be a substance that is colorless when not heated but develops color when heated, or a substance that develops color when it comes into contact with something coated on the transfer target. In addition to the colorants forming cyan, magenta, yellow, and black, colorants of various other colors can also be used.

The vehicle used is a mixture of a wax as a main component and a drying oil, a resin, a mineral oil, a cellulose, a rubber derivative, or the like.

Representative examples of wax include microcrystalline wax, carnauba wax, paraffin wax, and the like. Furthermore, various waxes are used, such as Fischer-Tropsch wax, various low molecular weight polyethylenes, wood wax, beeswax, spermaceti wax, privet wax, wool wax, shellac wax, candelilla wax, petrolatum, assorted waxes, fatty acid esters, and fatty acid amides. It will be done.

Further, in order to provide the hot-melt ink layer with good thermal conductivity and melt transferability, a thermally conductive substance can be blended into the hot-melt ink. Examples of this substance include carbonaceous substances such as carbon black, aluminum, copper, tin oxide, and molybdenum dioxide.

Methods for forming the ink layer on the matte layer include methods of applying the ink by hot melt coating, hot lacquer coating, gravure coating, gravure reverse coating, roll coating, and many other methods.

The thickness of the ink layer formed should be determined to balance the required density and thermal sensitivity, and should be between 0.1 and 30 μm.
m range, preferably 1 to 20 μm.

In the present invention, a surface layer can be further formed on the ink layer. The surface layer forms a part of the transfer film, forms the surface in contact with the transfer paper, seals the printed area of the transfer paper during transfer, prevents scumming, and prevents the ink layer from being covered. It has the function of improving adhesion to transfer paper. The wax used to form the surface layer is the same as the wax used in the hot-melt ink layer described above.

Further, when a heat-sensitive material is used as the base film, it is preferable to provide a heat-resistant slipping layer on the surface in contact with the thermal head to improve the slipperiness of the thermal head and prevent sticking. The basic components of the heat-resistant slipping layer are a heat-resistant resin and a substance that functions as a heat release agent or a lubricant. By providing such a heat-resistant slipping layer, thermal printing is possible without sticking even on thermal transfer sheets made of heat-sensitive plastic films as a base material. Benefits such as ease of use can be taken advantage of.

Since it goes without saying that the present invention can be applied to thermal transfer sheets for color printing, multicolor thermal transfer sheets are also included within the scope of the present invention. Further, as a thermal transfer printer, it can be applied to either a line or serial type.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

In the text, parts or percentages are based on weight unless otherwise specified.

Example 1 A polyethylene terephthalate film with a thickness of 3.5 μm was used as a base film, and one side of the film was used as a gravure roll with a fine tint pattern engraved with a matte layer forming ink having the composition shown below, and a gravure printing method was used. 0.3g/
A patterned matte layer was formed by printing and drying at a rate of rrr (dry state). Next, a heat-melting ink material having the following composition was applied at a rate of 3.5 g/r+f (dry state) and cooled to obtain a thermal transfer sheet of the present invention.

Matte ink, ■ CAP (482-05, manufactured by Kodak) 4.
0 parts PET (11E3200, Tg 65℃, manufactured by Unitika) 3, 0 parts colored carbon (Geast S, 66 mμ, manufactured by Tokai Electrode)
8.0 parts soybean lecithin (lecithin, Aji no Sodo) 0.2 parts crystalline cellulose (KC Flock W400, manufactured by Isumi Kokusaku Valve)
3.0 parts solvent (MEK/h
Ruen = 1/ri 81.8 part Shudankan Yue 2 fake carbon black (Diablack G, manufactured by Mitsubishi Kasei)
15 parts ethylene/vinyl acetate copolymer (EVA Frerus 31O1 manufactured by Mitsui Polychemicals) 8 parts paraffin wax (Paraffin 150
F, manufactured by Nippon Seiro Co., Ltd.) 50 parts carnauba wax 25 parts Next, using the above thermal transfer sheet, high-quality paper was used as the transfer paper, and thermal transfer printing was performed using a commercially available thermal head. It was difficult to read the white characters on the thermal transfer sheet after slight printing.

Example 2 Using a polyethylene terephthalate film with a thickness of 3.5 μm as a base film, gravure printing was performed using a gravure roll having fine wavy curves in parallel with a matte layer forming ink having the following composition on one side of the base film. 0 depending on the method
．． A patterned matte layer was formed by printing and drying at a rate of 3 g/rrr (dry state). Next, a heat-melting ink material having the composition shown below was applied at a rate of 3.5 g/rf (dry state) and cooled to obtain a thermal transfer sheet of the present invention.

Matte Ink SAN (Sevian AD, made by Daicel Chemical) 10.0 parts PET (TP220, Tg70℃, Nihon Gosei Kajikun) 2.0 parts Potassium titanate (Tismo D, made by Human Urine Chemical) 6.0 parts Conductive carbon (Ketchen Black EC, manufactured by Lion Akzo) 1.0 part mold release agent (Mold Vic F57, manufactured by Axel Plastics)
1.0 part solvent (MEK/l-luene=
1/l) 80.0 parts sad and longing Yuenoma 1 Carbon black (Diablack G, manufactured by Mitsubishi Kasei)
15 parts ethylene/vinyl acetate copolymer (EVA Flex 31O1 manufactured by Mitsui Polychemicals) 8 parts paraffin wax (paraffin 1
50F, made by Nippon Seiro) 50
25 parts carnauba wax Next, using the above thermal transfer sheet and using high-quality paper as the transfer paper, thermal transfer printing was performed using a commercially available thermal head.The resulting prints were thermal transfer after fine printing. The white text on the sheet was difficult to read.

Example 3 A polyethylene terephthalate film with a thickness of 3.5 μm was used as a base film, and one surface of the film was coated with a matte layer forming ink having the following composition to form 10 “r” particles per inch width.
A patterned matte layer was formed by printing and drying at a rate of 4.0 g/r/(dry state) by a gravure printing method using a gravure roll having the letters DIP J.

Next, 3.5 g/m of hot-melt ink material having the following composition was applied.
(I2 dry state) and cooling to obtain a thermal transfer sheet of the present invention.

Matte multi-ink SAN (Sevian AD, made by Daicel Chemical) 8.0 parts Potassium titanate (Tismo D, made by Human Urine Chemical) 6.0 parts Carbon (Geast 50143m 1tm, made by Tokai Electrode) 10.0 parts Soybean lecithin ( Lecithin, Ajinomoto W) 0,2i mold release agent (Mark FC
113, manufactured by Adeka Argus) 1.5 parts solvent (MEK/toluene = 1/1) 74.
Part 3 Anal Crest Yue 2/1 Carbon Black (Diamond Black G, manufactured by Mitsubishi Kasei)
15 parts ethylene/vinyl acetate copolymer (EVA Flex 31O1 manufactured by Mitsui Polychemicals) 8 parts paraffin wax (paraffin 1
50F, made by Nippon Seiro) 5
0 parts carnauba wax 25 parts Next, using the above thermal transfer sheet, high-quality paper was used as the transfer paper, and thermal transfer printing was performed using a commercially available thermal head. , The white characters on the thermal transfer sheet after printing were difficult to read.

(Effects) According to the present invention as described above, by having the same hue as the ink layer and providing it in a pattern, the white characters on the used thermal transfer sheet will be unreadable even if the ink layer is transferred. , there is no risk of leaking confidential information from used thermal transfer sheets.

Claims (2)

[Claims] (1) In a thermal transfer sheet in which a heat-melt ink layer is provided on one side of a base film via a matte layer, the matte layer has the same hue as the ink layer and is provided in a pattern. Features thermal transfer sheet. (2) The thermal transfer sheet according to claim 1, wherein the ink layer and the matte layer are black.