JPH0550996B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to improvements in thermal transfer sheets. In recent years, thermal recording methods using thermal heads have come into widespread use due to their advantages such as being noiseless, making the apparatus relatively inexpensive and compact, and being easy to maintain. One technology for thermal recording is thermal transfer, which does not develop secondary color due to heat or organic solvents and has excellent recording stability.In other words, thermal transfer sheets have a transfer ink layer that melts when heated on a base film. There is a method in which this transfer ink layer is transferred onto paper using a thermal head. Conventionally, paper such as condenser paper has been used as a base film for thermal transfer sheets. Since such thin paper has low strength and is particularly susceptible to tearing, it is desirable to use a strong plastic film such as polyester resin as the base material, but this is not actually used. This is because during printing, high heat of around 300° C. is applied from the thermal head to the thermal transfer sheet, which tends to cause the so-called staking problem in which the thermal head fuses to the base film. As a measure to enable the use of plastic film as a base material for heat-sensitive transfer sheets, a metal layer is provided by vapor deposition (Japanese Patent Application Laid-open No. 143152/1983).
or providing a heat-resistant protective layer of thermosetting resin (Japanese Patent Laid-Open No. 55-746), or using a supercooling substance as a lubricant (Japanese Patent Laid-Open No. 55-146790).
etc. were proposed. However, metal deposition must be done in batches, which inevitably increases costs, and if the thickness is made thick enough to be effective in preventing staking, resolution will be affected. The use of a protective layer of thermosetting resin is also usually 100℃.
The above-mentioned high heat treatment is necessary for curing, complicating the manufacturing process, and supercooling substances have drawbacks such as toxicity, odor, and corrosiveness to thermal heads. The present invention has been made in view of the drawbacks of the prior art as described above, and provides a thermal transfer sheet having a transfer ink layer that melts when heated on one side of a plastic film base material. Thermoplastic resin with alcoholic OH group on the surface
The present invention relates to a heat-sensitive transfer sheet characterized in that a protective layer is provided using a composition containing 5 to 40 parts by weight of a butylated polyvalent amine per 100 parts by weight. The present invention will be explained in more detail below. The base material of the plastic film used in the heat-sensitive transfer sheet of the present invention preferably has heat resistance and good thermal conductivity, and examples thereof include polyester film, polypropylene film, cellophane film, and cellulose acetate film. Appropriately, the thickness is around 10 μm, and for example, one as thin as 6 μm can also be used. The ink that is melted and transferred by heating uses a wax with an appropriate melting point, such as paraffin wax, microcrystalline wax, carba wax, etc., as a binder, and colorants such as carbon black, various dyes, and pigments. It is made by blending. Its manufacture and application onto a base film can be carried out according to known techniques. Next, to explain the protective layer that mainly characterizes the present invention, this protective layer is alcohol-based.
It is constructed using a composition containing a thermoplastic resin having an OH group and a butylated product of a polyvalent amine. In the above, thermoplastic resins having alcoholic OH groups include polyester resins, saponified vinyl chloride/vinyl acetate copolymers, polyether resins, OH-modified polybutadiene resins, acrylic polyols, urethanes or epoxy resins having alcoholic OH groups. Prepolymers or nitrocellulose resins, cellulose acetate butyrate resins, cellulose acetate resins, etc. are preferably selected. The above-mentioned resin may have an alcoholic OH group in its polymerized unit or may have an unreacted alcoholic OH group at the terminal or side chain. A butylated polyvalent amine is further added to the above thermoplastic resin having an alcoholic OH group. Polyvalent amines to be butylated include melamine, methylolmelamine, dicyandiamide, guanidine, biguanide, cyanomelamine, guanylmelamine, biuret, urea, ammeline, ammelide, guanamines such as formoguanamine, acetoguanamine, benzoguanamine, and phenylacetate. Guanamine, methoxyguanamine, etc. can be used. When using the butylated product of the above polyvalent amine, the curing catalyst may include ammonium phosphate, triethanolamine, acetamide, urea, pyridine,
Para-toluenesulfonic acid, sulfanilic acid, guanidine stearate, guanidine carbonate, etc. can be used in combination. The above butylated polyvalent amine is preferably added in an amount of 5 to 40 parts by weight, preferably 10 to 20 parts by weight, per 100 parts by weight of the thermoplastic resin having an alcoholic OH group. The degree of crosslinking and curing of the layer is too low to be effective;
If the amount exceeds 1 part by weight, the product produced by the reaction between butylated polyvalent amines will not have anti-stacking performance, which is not preferable. In addition, by adding the above butylated polyvalent amines to a thermoplastic resin having an alcoholic OH group, the adhesive strength of the protective layer to the plastic film is improved compared to when the butylated polyvalent amines are not added. increases. To construct a protective layer using each of the above compounds,
After each compound is dissolved in a suitable solvent and adjusted to a viscosity suitable for coating, it may be coated on one side of a plastic film base material by a known coating method. The thermal transfer sheet of the present invention basically has the above structure, but may be further modified as follows. First, a plus swimmer layer may be provided between the plastic film substrate and the protective layer to improve adhesion. The primer layer can be provided using a known primer paint, but for example, as a binder, acrylic resin, polyester resin, polyvinyl acetate resin, vinyl chloride/vinyl acetate resin, polyol and diisocyanate, polyol and melamine, epoxy resin. and diisocyanates, etc., and when a primer paint made with these binders is used, the adhesion strength is particularly improved when a polyester film is used as the base material. Second, in order to improve the slippage of the thermal head, it is recommended to add a lubricant or a heat release agent to the protective layer.
Waxes such as polyethylene wax and paraffin wax, higher fatty acid amides, higher fatty acid esters, higher fatty acid salts, higher alcohols, the first group such as phosphate esters such as lecithin, and powders of fluororesins such as polytetrafluoroethylene. Examples of the second group include powders of vinyl fluoride resin, powders of guanamine resin, boron nitride, silica, wood powder, talc, etc. The above-mentioned lubricants or thermal mold release agents can be used in any desired mixture, and it is desirable to add them to the protective layer in an amount of about 10 to 100% by weight. These lubricants or thermal release agents are added and kneaded when preparing the coating material for forming the protective layer. In the above, those belonging to the first group are melted by heating and exhibit the action of a lubricant or heat mold release agent, and those belonging to the second group are those that exhibit the action of a lubricant or heat mold release agent in the state of solid powder. It is. Since the thermal transfer sheet of the present invention has the above-described structure, thermal printing is possible without staking even on a thermal transfer sheet based on plastic film, and the plastic film is difficult to cut and processing is easy. Benefits such as ease of use can be taken advantage of. Further, the protective layer in the present invention can be formed using a common coating device and does not require any special high heat treatment. Examples and comparative examples are listed below to explain the present invention more specifically. Example 1 The following inks were prepared. Ink A Cellulose acetate propionate resin (manufactured by Kodatsu, CAP504-02) 10 parts by weight Butylated melamine (manufactured by Nippon Reichhold, Supervecamine J-820) 1 part by weight para-toluenesulfonic acid 0.3 parts by weight Toluene 13 parts by weight Isopropanol 13 parts by weight Methyl ethyl ketone 13 parts by weight Ink B Parafine wax 10 parts by weight Carnauba wax 10 parts by weight Polybutene (manufactured by Nippon Oil, HV-100)
1 part by weight carbon black (manufactured by Tokai Electrode, Seast S)
2 parts by weight 6μmm thick polyester film (manufactured by Toray,
A protective layer was formed by applying Ink A to the surface of the 2000 (Lumirror) by a gravure coating method so that the dry thickness was 1.5 g/m ² . Next, use ink B on the back side of the film to check the temperature.
A transfer ink layer with a thickness of 5 μm was formed by hot melt coating at 100°C. Ink A and Ink B were applied using a polyester film having a thickness of 12 μm in the same manner as above. The head runnability etc. when printing was performed using the heat-sensitive transfer sheet obtained as described above are summarized in Table 1 below together with other examples. Example 2 Ink C and Ink D having the following compositions were prepared. Ink C (primer) Polyester resin (manufactured by Toyobo, Pylon 200)
3 parts by weight Vinyl chloride/vinyl acetate copolymer (Union Carbide, Vinyrite VAGH) 3 parts by weight isocyanate (Takenate D-110N, Takeda Pharmaceutical) 1 part by weight Toluene 20 parts by weight Methyl ethyl ketone 20 parts by weight Ink D Cellulose Acetate Pro Pionate resin (manufactured by Kodatsu, CAP504-02) 10 parts by weight Butylated melamine (manufactured by Nippon Reichhold, Supervetsukamine J-820) 1 part by weight para-toluenesulfonic acid 0.3 parts by weight Polyethylene wax (manufactured by Asahi Denka, Mark)
FC113, 30% toluene dispersion) 3 parts by weight Phosphate ester thermal mold release agent 3 parts by weight Toluene 13 parts by weight Isopropanol 13 parts by weight Methyl ethyl ketone 13 parts by weight One side of the same polyester film as used in Example 1 Using the gravure coating method, ink C and ink D were applied in order to a dry thickness of 1 g/
It was applied so that it was ² m2. Furthermore, in the same manner as in Example 1, a transfer ink layer was formed on the back side of the polyester film using Ink B. The above operations were performed to a thickness of 6 μm.
and 12μmm film. Thermal transfer sheets obtained in the above first and second examples, Comparative Example 1 in which a protective layer was provided, and Comparative Example 2 in which the protective layer was formed with a phenol resin paint and cured at a temperature of 150°C. The runnability of the head when printing under the following conditions using a
The conditions of the thermal transfer sheets and the printing quality were compared, and the results shown in Table 1 below were obtained. Head Thin film type Printing energy 1mJ/dot (4 x 10 ^-4 cm ² ) Transfer layer High quality paper (Sanyo Kokusaku Pulp, KYP135Kg)

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Claims (1)

[Scope of Claims] 1. In a thermal transfer sheet having a transfer ink layer that melts when heated on one side of a plastic film base material, 100% by weight of a thermoplastic resin having an alcoholic OH group on the other side of the base material. 1. A heat-sensitive transfer sheet comprising a protective layer formed using a composition containing 5 to 40 parts by weight of a butylated polyamine. 2. The heat-sensitive transfer sheet according to claim 1, wherein a substance having the action of a lubricant or a heat release agent is added to the protective layer.