JPH01214477A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE:To prevent staining on a transfer recording paper from being caused by a heat-fusible ink layer in an N-times mode process, by providing a transfer material comprising the heat-fusible ink layer and a surface layer on one side of a base film, and causing the surface layer to comprise a lubricating material and become substantially colorless after thermal transfer. CONSTITUTION:A heat-fusible ink layer is provided on a base film, and a surface layer provided on the ink layer comprises a lubricating material. The lubricating material may is a lubricant such as a silicone resin having a relatively low melting point, a silicone wax, a fluororesin, a fluorine-containing wax, a higher fatty acid amide and an ester, which may be used either singly or in combination. The surface layer is provided by applying an aqueous dispersion containing the lubricating material, followed by drying at a temperature not higher than the melting point of the lubricating material. Thus, the surface layer comprising the lubricating material is provided in a substantially uncolored state, whereby the coefficient of friction between a transfer recording material and this thermal transfer sheet is lowered even in an N-times mode process, and staining on the recording material and stringing in printing can be obviated.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to improvements in thermal transfer sheets, and more specifically to a general thermal transfer method and a thermal transfer method in which the conveyance speed of the transfer material is set higher than the conveyance speed of the thermal transfer sheet. The present invention relates to a thermal transfer sheet that can prevent scumming of transfer paper due to a heat-fusible ink layer in a thermal transfer sheet (hereinafter simply referred to as the N-time mode method).

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

This conventional thermal transfer sheet uses a paper such as capacitor paper or paraffin paper with a thickness of 10 to 20 μm, or a plastic film such as polyester or cellophane with a thickness of 3 to 20 μm as a base film, and contains pigments, dyes, etc. in wax. This product is manufactured by coating a layer of hot-melt ink mixed with a coloring agent.

When a conventional thermal transfer sheet is used to print on a transfer paper, the ink layer comes into direct contact with the transfer paper surface, and the friction between the two often causes scumming in non-printed areas.

In addition, in the N times mode method, the conveyance speed of the transferred material is N,
If the transport speed of the thermal transfer sheet is N', and N>N', the printing distance is N, but the consumption distance of the thermal transfer sheet is N', so the amount of consumption of the thermal transfer sheet can be saved relative to the printing distance. However, since the transfer material and the thermal transfer sheet constantly move relative to each other and are rubbed against each other, the printed characters are rubbed and smeared, and the printed characters become stringy and the printed characters are damaged. There are problems in that the density is low and the print quality is poor.

The present invention was made against the background of the above-mentioned circumstances,
The purpose is to provide a thermal transfer sheet that does not cause scumming or stringiness even when thermal transfer is performed using the N-times mode method, and can provide clear prints.

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

That is, the present invention provides a thermal transfer sheet in which a transfer material consisting of two layers, a heat-melting ink layer and a surface layer, is formed on one side of a base film, the surface layer being made of a slippery material, The thermal transfer sheet is characterized in that the layer is substantially uncolored after thermal transfer.

(Function) When forming the surface layer, by forming the surface layer substantially uncolored from a slippery material such as a silicone material or a fluorine material, the transfer material and the thermal transfer sheet can be easily bonded even in the N-fold mode method. The coefficient of friction of the paper was reduced, and the problems of scumming on the transfer material and stringy printing were solved.

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

The thermal transfer sheet of the present invention has a heat-fusible ink layer on one surface of a base film, and further has a surface layer made of a slippery material formed thereon.

As the base film used in the present invention, the same base film used in conventional thermal transfer sheets can be used as is, and other base films can also be used, and there are no particular limitations.

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, ionomer, etc. Examples include plastics, papers such as condenser paper and paraffin paper, and nonwoven fabrics, and base films made of composites of these materials may also be used.

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.
It is m.

The hot-melt ink used in the present invention comprises a colorant 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.

Further, 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 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. Furthermore, Fischer-Tropsch wax, various low molecular weight polyethylenes, wood wax, beeswax, spermaceti wax, privet wax, wool wax, shellac wax, candelilla wax, petrolactam, polyester wax, partially modified wax, fatty acid ester, fatty acid amide, etc. Various waxes are used. 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 directly or indirectly forming a hot-melt ink layer on the base film include applying the above-mentioned ink by hot melt coating, hot lacquer coating, gravure coating, gravure reverse coating, roll coating, and many other methods. Examples include methods. The thickness of the ink layer formed should be determined to balance the required concentration and thermal sensitivity and is in the range of 0.1 to 30 μm, preferably in the range of 1 to 20 μm.

In the present invention, the surface layer formed on the ink layer is made of a slippery material. Preferred lubricant materials for the purpose of the present invention include lubricants such as silicone resins, silicone waxes, fluorine resins, fluorine waxes, higher fatty acid amides, and esters having relatively low melting points. They can be used alone, mixed with each other, or mixed with the various waxes mentioned above. When mixed with wax, an oily lubricant such as silicone oil can also be used. Further, when used in combination with the above-mentioned waxes, it is preferred that the lubricating material accounts for at least 10% by weight of the mixture.

The surface layer made of the above material may be formed by any method, but a preferred method is to use an aqueous dispersion containing a slippery material (and wax). A particularly preferred method is to use a mixture of an aqueous dispersion of a slippery material and an aqueous dispersion of wax, coat the mixture on a hot melt ink layer, and dry at a temperature below the melting point of the slippery material (and wax). It is. By doing this, the surface layer is formed while the slippery material (and wax) maintains its particle shape, and the slipperiness of the surface layer is best exhibited.

The aqueous medium containing the lubricating material (and wax) is water or a mixture of water and a water-soluble organic solvent, such as methanol, ethanol, isopropanol, such as water-soluble organic solvent per 100 parts by weight of water. By using 5 to 200 parts by weight, the wettability of the wax aqueous dispersion to the hot-melt ink layer is improved.

Furthermore, the aqueous dispersion of the lubricating material (and wax) may contain a small amount of known additives such as an emulsifier (surfactant) and a leveling agent. The solid content of this dispersion is approximately 1
It is about 0 to 50% by weight.

In the present invention, a thermoplastic resin having a relatively low melting point can also be mixed into the dispersion, thereby improving the adhesion of the formed surface layer to the material to be transferred. Examples of such thermoplastic resins include ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid ester 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, etc. Particularly preferred are those having a softening point lower than those conventionally used as heat-sensitive adhesives, for example, from 50 to 80°C.

The ratio of the lubricating material (and wax) to the thermoplastic resin is preferably within a weight ratio of 5 to 300 parts of the thermoplastic resin to 100 parts of the lubricating material (and wax).

The surface layer formed from the slippery material (and wax) is formed by applying an ink composition containing the slippery material (and wax) using a conventionally known coating method and drying. Drying at a temperature above the melting point of the slippery material (and wax) will form a smooth surface layer, while drying at a temperature lower than the melting point of the slippery material (and wax) will result in the formation of a smooth surface layer. A surface layer having a finely uneven surface in which the particle shape remains is formed.

In the present invention, the thickness of the surface layer formed as described above is preferably 0.1 μm or more and less than 5 μm so that sensitivity will not be insufficient even when the printing energy is low as in a high-speed printer. be. This thickness is 0
．． If the thickness is less than 1 μm, there is a risk that the transfer paper and the ink layer will rub against each other, resulting in scumming.

The surface layer is substantially uncolored, and may be colored white by adding an appropriate amount of extender pigment or white pigment.

When a heat-resistant 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 remain solid, such as fluororesin and inorganic substance powders. There is.

By providing such an anti-sticking layer, thermal printing can be performed without causing sticking even on thermal transfer sheets based on heat-sensitive plastic films, thereby reducing the difficulty of cutting and processing of plastic films. Benefits such as ease of use can be taken advantage of.

Thermal transfer images generally have glossy and beautiful prints, but the documents may become difficult to read, so matte prints are sometimes desirable. In such a case, for example, as proposed by the applicant (Japanese Patent Application No. 58-208306),
It is preferable to form a matte layer by coating a base film with an inorganic pigment such as silica, calcium carbonate, etc. dispersed in an appropriate solvent, and then coat a heat-melting ink layer to form a thermal transfer sheet. . Alternatively, the base film itself may be matted and used (this is the technique disclosed in Japanese Patent Application No. 1983-208307, also proposed by the applicant).

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.

(Effects) According to the present invention as described above, when forming the surface layer, by forming the surface layer substantially uncolored from a slippery material such as a silicone material or a fluorine material, -numerical thermal transfer Of course, even in the N-time mode method, the coefficient of friction between the transfer material and the thermal transfer sheet was reduced, and the background smearing of the transfer material and the stringy print phenomenon were solved.

(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 on one side of the base film, a heat-melting ink and a surface layer material having the following compositions were prepared, applied and dried by the methods described respectively. A thermal transfer sheet of the present invention was obtained.

Carbon black (dia black G, manufactured by Mitsubishi Kasei)
15 parts ethylene/vinyl acetate copolymer (EV Hachiraflex 310 manufactured by Mitsui Polychemicals) 8 parts paraffin wax (paraffin 15
50 parts carnauba wax (manufactured by Nippon Seiro) 50 parts carnauba wax 25 parts Using an attritor, the mixture was kneaded at 120°C for 6 hours, and then 3',
It was coated and dried at a rate of 5 g/rn' (dry state).

Surface layer silicone modified polyurethane resin (molecular placement piece 2.800
, melting point 84°C) (solid content 40%, aqueous emulsion) 20 parts paraffin wax (solid content 40%, aqueous emulsion)
20 parts 60% Impropatool aqueous solution
It was applied at a rate of 0.8 g/rn2 (dry state) by a 15-part gravure coating method and dried at 60°C to form a matte surface layer.

The thickness of the ink layer and the surface layer is 3.5 μm and 0.8 μm, respectively.
Thermal transfer printing was carried out using the above-mentioned thermal transfer sheet of M, and several types of transfer papers were selected from high-quality paper with high smoothness to medium-quality paper with low smoothness, using a commercially available thermal head. The energy of the thermal head is 0.7 W/dot, the conveying speed of the transfer paper (N) is 40 cm/sec, and the conveying speed of the thermal transfer sheet (
N') When high-speed printing was performed at 20 cm/sec in the N-times mode of N/N' = 2, high-quality printing was performed on all transfer papers with no background smudges or stringy prints. .

Example 2 Using the same base film as in Example 1, two layers having the following compositions were formed to obtain a thermal transfer sheet of the present invention.

Mixed Enemy Ino Nbrow Carbon Black (Tire Black G, manufactured by Mitsubishi Kasei)
15 parts ethylene/vinyl acetate copolymer (EVA Flex 310, manufactured by Mitsui Polychemicals) 8 parts paraffin wax (paraffin 15
50 parts carnauba wax (manufactured by Hiki Seiro) 50 parts carnauba wax 25 parts Attritor was kneaded at 120°C for 6 hours, and the ink temperature was 3.5% by hot melt roll coating at 120°C.
It was applied and dried at a rate of g/rn' (dry state).

Surface layer fluorine-modified acrylic resin (molecular weight 3,200, melting point 7
0°C, solid content 40%, aqueous emulsion) 40 parts Paraffin wax emulsion (solid content 40%, aqueous emulsion) 30 parts EVA resin emulsion (Bond Wax 62-357, manufactured by Pond Wax Co., Ltd., solid content 40%) 10 parts 50 % isopropanol aqueous solution 50 parts was coated by gravure coating at a rate of 0.5 g/rn' (dry state) and dried at 73°C to form a surface layer with a smooth surface.

The thickness of the ink layer and surface layer is 3.5 μm and 0.5 μm, respectively.
This thermal transfer sheet of Example 1 also showed good transfer performance as in Example 1.

Example 3 Using the same base film as in Example 1, two layers having the following compositions were formed to obtain a thermal transfer sheet of the present invention.

Butyosis Melting Eyebrow Carbon Black (Diablack G, manufactured by Mitsubishi Kasei)
15 parts ethylene/vinyl acetate copolymer (EV Yahelex 31O5 manufactured by Mitsui Polychemicals) 8 parts paraffin wax (Paraffin 15 Ko, manufactured by Nippon Sabaro) 50 parts carnauba wax 25 parts 6 parts using an attritor at 120°C 3.5g of the kneaded material was coated with hot melt roll coating at an ink temperature of 120°C.
/rn' (dry state) and dried.

Surface layer silicone oil: 3 parts Carnauba wax: 10 parts Ethylene/vinyl acetate copolymer resin: 2 parts After melting and emulsifying (solid content: 20%), 0.3 parts was coated using a roll coating method.
g/rn' (dry state) and dried at 60°C to form a matte surface layer.

The thickness of the ink layer and the surface layer is 3.5 μm and 0.3 μm, respectively.
The transfer sheet of this example also exhibited good transfer performance with no scumming.

Example 4 A polyethylene terephthalate film with a thickness of 6 μm was used as a film to produce yellow (Y) having the following composition.
A thermal transfer sheet of the present invention was obtained by forming an ink layer and a surface layer using heat-melting inks of each color, magenta (M), cyan (C), and black (B) and a surface layer ink.

Pigment (yellow, magenta, cyan or black pigment), 4-part ethylene/vinyl acetate copolymer (Sumitate KC-10, manufactured by Sumitomo Chemical)
7.5 parts oxidized paraffin ester complex compound (
Amidopolymer T-820, made by Denka Polymer) 12.5
Part paraffin wax (Paraffin 5P-0145, manufactured by Nippon Seiro) 15 parts Microcrystalline wax (Himic 2065, manufactured by Nippon Seiro)
10 parts isoproper tool
5 parts xylene 46
Section: An ink layer was formed by sequentially printing yellow, magenta, cyan, and black in the order of yellow, magenta, cyan, and black by a gravure printing method using the ink compositions of the above four colors. The coating weight at that time was 4 g/+772 (dry).

Surface layer silicone modified polyurethane resin (molecular setting piece 3.200
, melting point 73°C, solids content 40%, aqueous emulsion)
10 parts carnauba emulsion (WE-95, manufactured by Bond Wax Co., Ltd., solid content 40%)
30 parts 75% Impropatool aqueous solution
60 parts Using the above ink composition, a dry weight of 0.0.
A surface layer was formed by coating at a concentration of 7 g/rn2. The drying conditions at that time were 65°C for 3 seconds.

When the thermal transfer sheet of the present invention created through the above process was used to print with a color thermal printer in the N-fold mode with N/N' = 1.7, there was no background smudge caused by rubbing the paper and film. There wasn't.

Patent applicant: Dai Nippon Printing Co., Ltd. Agent: Patent Attorney Yoshi 1) Katsutou＼

Claims (3)

[Claims] (1) A thermal transfer sheet in which a transfer material consisting of two layers, a heat-melting ink layer and a surface layer, is formed on one side of a base film, the surface layer being made of a slippery material, and after thermal transfer, A thermal transfer sheet characterized by a substantially uncolored layer. (2) Claim No. 1 used in a thermal transfer method in which the conveyance speed of the transfer material is higher than the conveyance speed of the thermal transfer sheet when the thermal transfer sheet and the transfer material are overlapped and thermal transfer is performed with a thermal head. ) Thermal transfer sheet described in section. (3) The thermal transfer sheet according to claims (1) and (2), wherein the slippery material is a silicone-based material or a fluorine-based material.