JPH06239043A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE:To ensure the sufficient sliding to the smooth running of a thermal head by providing a specific heat-resistant protective layer consisting of a thermoplastic resin, an organometal salt and high mol.wt. silicone to the rear surface of a base material film having a thermal transfer ink layer arranged on the surface thereof. CONSTITUTION:A thermal transfer sheet is constituted by arranging a thermal transfer ink layer 102 on the surface of a base material film 101 composed of a plastic film. In this case, a heat-resistant protective layer 103 having specific constitution is provided on the rear surface of the base material film 101. That is, the heat-resistant protective layer 103 is formed from a compsn. consisting of at least a thermoplastic resin, an organometal salt and high mol.wt. silicone and the compounding ratio of this compsn. is set so that 5-50 pts.wt. of the organometal salt and 0.5-10 pts.wt. of high mol.wt. silicone are compounded with 100 pts.wt. of the thermoplastic resin. High mol.wt. silicone is formed from a compsn. having viscosity of 5000cst or more at 20 deg.C.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a thermal transfer sheet.
In particular, the present invention relates to a thermal transfer sheet for a thermal transfer printer used as a hard copy output device such as a personal computer or a word processor, and more particularly to a thermal transfer sheet having a heat resistant protective layer for preventing sticking during image formation and printing.

[0002]

2. Description of the Related Art Conventionally, when a hard copy of a personal computer or a word processor is printed by a thermal transfer method, wax is mixed with a coloring material such as a pigment or a dye on one surface (surface) of a base film as a thermal transfer sheet. The applied ink is applied by a coating device, and a fusion type thermal transfer sheet provided with a heat-fusible ink layer, or an ink in which a sublimable dye is dispersed in a binder is applied by a coating device,
Sublimation type thermal transfer sheets provided with a heat-sensitive sublimation ink layer are often used. In the heat-melting type heat transfer sheet, printing is performed by heating and pressing a predetermined portion from the back side of the substrate film with a thermal head to transfer the heat-melting ink layer to a heat transfer material such as paper. Further, in the sublimation type thermal transfer sheet, a predetermined position is heated and pressed from the back side of the base material film by a thermal head to sublimate the sublimable dye and permeate and color the dedicated image-receiving paper for image formation and printing.
The other surface (back surface) of these base films is usually called a back layer, and a heat-resistant protective layer is provided to prevent sticking during image formation and printing.

As a conventional heat-resistant protective layer, for example, a method of providing a curable silicone-modified resin layer on the back surface of a substrate film, a method of providing a layer composed of a thermoplastic resin and a high-molecular-weight silicone oil, a thermoplastic resin and an organic material. A method of providing a layer composed of a metal salt is known.

However, in such a conventional method, there were problems in production and it was not possible to satisfy all the performances required for the back layer. For example, when a curable silicone-modified resin layer was provided, long-term aging was required to obtain sufficient heat resistance. Therefore, there are manufacturing problems such as it takes time to evaluate the characteristics and confirm the quality of the backside processed base material film, and the space for equipment for aging becomes large. Furthermore, while aging in the wound state,
Since the front and back surfaces of the base film are in contact with each other, the silicone component moves from the back surface of the back surface of the base film processed to the front surface, and is applied to repel the coating ink when processing the thermal transfer ink layer. It could be impossible. On the other hand, a mixed system of thermoplastic resin and high-molecular-weight silicone does not require aging in the manufacturing process, but it is unavoidable that dirt adheres to the thermal head, and a thermal transfer printer that uses this type of thermal transfer sheet. Then, it was necessary to always pay attention to the contamination of the thermal head. Further, in the mixed system of the thermoplastic resin and the metal soap, the slipperiness for smooth running of the thermal head is insufficient, wrinkles occur on the thermal transfer sheet during printing work, and the problem of causing printing defects, Was often there.

[0005]

SUMMARY OF THE INVENTION The present invention aims to solve the above-mentioned individual drawbacks of the prior art and provides a comprehensively superior heat-resistant protective layer.

[0006]

[Means for Solving the Problems] In order to achieve such an object, the inventors of the present invention have earnestly studied, and as a result, formed a dye layer composed of a dye and a binder resin on one surface of the substrate film. In a thermal transfer sheet having a heat-resistant protective layer formed on the other surface, the heat-resistant protective layer contains at least a thermoplastic resin, an organic metal salt and a high molecular weight silicone as a composition, and the blending ratio of these compositions is a thermoplastic resin. 100
5 to 50 parts by weight of the organometallic salt, 0.5 to 10 parts by weight of the high molecular weight silicone, and the high molecular weight silicone is composed of a composition having a viscosity of not less than 5000 cSt at 20 ° C. It was found that the thermal head has sufficient slipperiness for smooth running, and at the same time prevents dirt from adhering to the thermal head.

[0007]

EXAMPLES The thermal transfer sheet of the present invention will be described in more detail with reference to the drawings. As shown in FIG. 1, the thermal transfer sheet of the present invention has a thermal transfer ink layer 1 of a thermal melting transfer type or a thermal sublimation transfer type on one surface (front surface) of a substrate film 101.
02 is formed. Further, the back surface layer 103 is formed on the other surface (back surface) of the base material film 101, and this back surface layer is a heat-resistant protective layer and comprises a thermoplastic resin, a high molecular weight silicone, and an organic metal salt. The main composition is to have sufficient slipperiness for smooth running of the thermal head, and at the same time prevent dirt from adhering to the thermal head. As for the type of the thermal transfer ink layer 102, it is obvious that the present invention can be applied to any type, and therefore, the thermal melt transfer type will be described below as an example.

The substrate film 101 used in the present invention may be the same as the substrate film used in the conventional thermal transfer sheet and is not particularly limited. Specific examples of preferred substrate film include, for example, polyester, polypropylene, cellophane, polycarbonate, cellulose acetate,
Examples include polyethylene, polyvinyl chloride, polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin, chlorinated rubber, plastic films such as ionomers, paper such as condenser paper and paraffin paper, and non-woven fabrics. It may be a base film that is a composite of any of the above. The thickness of such a base film 101 can be appropriately selected depending on the material used so that the strength and thermal conductivity are appropriate, and for example, is preferably about 2 to 25 μm.

The thermal transfer ink layer 102 formed on the surface of the substrate film 101 contains a colorant and a vehicle as main components, and various additives can be added if necessary. The thickness of the ink layer 102 to be formed can be determined so that the required concentration and thermal sensitivity can be balanced, and normally a range of about 1 to 10 μm is preferable.

The colorant can be appropriately selected from known organic or inorganic pigments or dyes,
For example, those having a sufficient coloring density and not discolored or discolored by light, heat or the like are preferable. Further, it may be a substance that develops a color by heating or a substance that develops a color by coming into contact with a component applied to the surface of the transfer target.
Furthermore, the color of the colorant is not limited to cyan, magenta, yellow and black, and colorants of various colors can be used.

As the vehicle, wax is the main component, and in addition, a mixture of wax with a drying oil, a resin, a mineral oil, cellulose, a rubber derivative or the like is used. Typical examples of waxes include microcrystalline wax, carnauba wax, and paraffin wax. Further, Fischer-Tropsch wax, various low-molecular-weight polyethylene, wood wax, beeswax, spermaceti wax, ivowa wax, wool wax, shellac wax, candelilla wax, petrolactam, partially modified wax, fatty acid ester, fatty acid amide and other waxes are used. . Among these, waxes having a freezing point of 50 to 70 ° C. and a melt viscosity at 100 ° C. of 10 to 200 mPas are particularly preferable.

When the adhesiveness between the base film 101 and the thermal transfer ink layer 102 is insufficient, the thermal transfer ink layer 102 may be formed via an adhesive layer. The adhesive layer can be formed of an acrylic resin, a nylon resin, a vinyl chloride copolymer, a polyester resin, a urethane resin or the like, and preferably has a thickness of about 0.1 to 0.2 μm.

In the present invention, the above thermal transfer ink layer 1
You may form the background stain prevention layer which consists of colorless wax on 02 as a surface layer. Further, the surface layer may have a property of improving the transferability to the heat transfer sheet.

In the thermal transfer sheet of the present invention, the back layer formed on the other surface of the base film 101 has a thermoplastic resin, a high molecular weight silicone, and an organic metal salt as a main composition, and if necessary, various materials can be used. Additives can be added. The thermoplastic resin used is not particularly limited, but is preferably an acrylic resin, for example, polymethyl methacrylate, polyethyl methacrylate polyacrylic acid ester, polyacrylic acid ethyl ester, polyacrylic acid butyl ester, etc. are mainly used. A component having a molecular weight of 100,000 or more and a Tg of 80 ° C. or more is excellent in sticking resistance and head contamination resistance.
As a high molecular weight silicone, the viscosity at 20 ° C is 5
It is preferably 000 cSt or more, more preferably 1
The blocking property is further improved by using one having a viscosity of 1,000,000 to 1,000,000 cSt. Examples of these include polydimethylsiloxane, methylphenyl silicone, methylhydrogen silicone, and the like. Two
If the viscosity at 0 ° C. is 5000 cSt or less, problems such as set-off occur. The organic metal salt has 18 to 18 carbon atoms.
Preferred are 30 alkylphosphoric acid metal salts and 30 alkylcarboxylic acid metal salts such as zinc stearate, sodium stearate, zinc behenyl phosphate, and aluminum behenate. The preferred blending ratio of these compositions is 100 parts by weight of the thermoplastic resin,
5 to 50 parts by weight of an organic metal salt, and 0.5 to 0.5 of a high molecular weight silicone having a viscosity at 20 ° C. of 5000 cSt or more.
It is 10 weight. If the amount of the organic metal salt is less than 5 parts by weight, head scum is generated, and if the amount of the organic metal salt is more than 50 parts by weight, the friction of the head is increased, and problems such as wrinkles and head scum are generated. High molecular weight silicone is 0.5
If it is less than 10 parts by weight, wrinkles are generated, and if the amount of high molecular weight silicone is more than 10 parts by weight, storability is poor and an organometallic salt or high molecular weight silicone is deposited to cause problems such as blocking.

As an additive, a polyester resin, a polyurethane resin or the like can be used in order to impart adhesiveness to the substrate. Further, various kinds of inorganic and organic fillers can be added, and the addition thereof improves the characteristics. For example, the addition of a melamine filler has the function of increasing the blocking prevention effect of the thermal transfer sheet.

These compositions are dispersed in an organic solvent such as MEK or toluene by using a dispersing device such as an attritor, a ball mill, a sand mill, etc. to produce a coating liquid for the back layer, and a gravure coater and a roll are used. Using a coating device such as a coater to coat the base film with a thickness of 0.01 to 1.0
Form a backside layer of μm. The thermal transfer sheet of the present invention is produced by kneading the composition of the above ink layer on the other surface of the substrate film thus provided with the back layer by using a sand mill while heating at 90 ° C. Then, it is applied by a roll coating method or the like to form an ink layer, and the thermal transfer sheet of the present invention is manufactured.

(Example 1) Ink composition for back layer PMMA (manufactured by Mitsubishi Rayon Co., Ltd., Dianal BR85) 100.0 parts Polydimethylsiloxane (manufactured by Shin-Etsu Chemical Co., Ltd. KF-96-5000 cSt) 5.0 Parts (Note) Viscosity at 20 ° C 5000 cSt Organometallic salt (Sakai Chemical Co., Ltd. LBT2230) 10.0 parts Polyester resin (Unitika Co., Ltd. Elitel 3200) 3.0 parts MEK 800.0 parts Toluene 50.0 parts Ink composition for ink layer Wax ink layer 28.9 parts Carbon black (Diamond Black manufactured by Mitsubishi Chemical Co., Ltd.) 6.6 parts Ethylene / vinyl acetate copolymer (Evaflex 310 manufactured by Mitsui Polychemical Co., Ltd.) 10. 0 parts Carnauba wax 9.0 parts Paraffin wax (freezing point = 70 ° C., melt viscosity = 80 mPas ) In 70.0 parts The above ink composition, firstly the substrate film is
The back layer ink composition was applied to one surface of a polyethylene terephthalate film (Lumirror thickness of 4.5 μm manufactured by Toray Industries, Inc.) and dried to form a back layer having a thickness of 0.15 μm. Next, the ink composition for the ink layer is prepared, and the other side of the substrate film is coated and dried using a wire bar to form a heat-meltable ink layer having a thickness of 2 μm to obtain the thermal transfer sheet of the present invention. Obtained. (Example 2) Ink composition for back layer High molecular weight silicone was changed to polydimethylsiloxane (KF-96H-300000cSt, Shin-Etsu Chemical Co., Ltd.) 5.0 parts (Note): Viscosity at 20 ° C was changed to 300,000 cSt, and melamine filler (Japan) was used. Same as Example 1 except that 10.0 parts of Eposter S manufactured by Catalyst Co., Ltd. was added.

Comparative Example 1 Ink composition for back layer Organic metal salt (LTB2230, manufactured by Sakai Chemical Industry Co., Ltd.) 3.0 parts The same as in Example 1 except that 3.0 parts were used. (Comparative Example 2) The same as Example 1 except that the ink composition for the back layer, organometallic salt (LBT2230, manufactured by Sakai Chemical Industry Co., Ltd.) was 100.0 parts. (Comparative Example 3) Ink composition for back layer polydimethylsiloxane (KF-96-5000 cSt, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.3 part (Note) Same as Example 1 except that the viscosity at 20 ° C is 5000 cSt. (Comparative Example 4) Ink composition for back layer polydimethylsiloxane (KF-96-5000 cSt, manufactured by Shin-Etsu Chemical Co., Ltd.) 50.0 parts (Note) Same as Example 1 except that the viscosity at 20 ° C is 5000 cSt. (Comparative Example 5) Ink composition for back layer polydimethylsiloxane (KF-96-3000 cSt, manufactured by Shin-Etsu Chemical Co., Ltd.) 5.0 parts (Note) Same as Example 1 except that the viscosity at 20 ° C was 3000 cSt.

The results of evaluating the printability, the printability after storage, and the smearing of the thermal head in the above Examples and Comparative Examples are shown in Table 1, which shows that the present invention is excellent. ing. The examples 1 and 2 are good in terms of printability, printability after storage, and head contamination without any problems. In Example 2, a higher molecular weight silicone is used, and the addition of a melamine filler makes it more excellent in blocking resistance. In Comparative Example 1, the compounding ratio of the organic metal salt is small, and the head is contaminated. Comparative example 2
In the case of, the blending ratio of the organic metal salt is too large, resulting in poor sliding and wrinkling. In Comparative Example 3, the mixing ratio of the silicone resin is small and the head does not stain, but wrinkles occur during printing. In Comparative Example 4, although the blending ratio of the silicone resin is too large and the printability is good, blocking and set-off occur after storage, and the thermal transfer ribbon runs poorly and the head becomes dirty. In Comparative Example 5, the viscosity of the silicone resin is low and set-off is easy.

[Table 1]

[0020]

EFFECTS OF THE INVENTION The backside layer of the thermal transfer sheet is composed mainly of a thermoplastic resin, a high molecular weight silicone and an organic metal salt, so that the thermal head has sufficient slipperiness for smooth running and at the same time is applied to the thermal head. It was possible to provide a thermal transfer sheet having a comprehensively excellent heat-resistant protective layer capable of preventing the adhesion of dirt.

[Brief description of drawings]

FIG. 1 is a sheet cross-sectional view showing the structure of a thermal transfer sheet of the present invention.

[Explanation of symbols]

 101 Base Film 102 Thermal Transfer Ink Layer 103 Heat Resistant Protective Layer

Claims (1)

[Claims] 1. A thermal transfer sheet having a thermal transfer ink layer on the surface of a base film made of a plastic film, wherein at least a thermoplastic resin, an organic metal salt and a high molecular weight silicone are used as a composition on the back side of the base film. The blending ratio of these compositions is 5 to 50 parts by weight of the organic metal salt, 0.5 to 10 parts by weight of the high molecular weight silicone, and the viscosity at 20 ° C. of the high molecular weight silicone is 100 parts by weight of the thermoplastic resin. A thermal transfer sheet comprising a heat-resistant protective layer composed of a composition having a viscosity of 5000 cSt or more.