JPH0435356B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a thermal transfer material. (Prior Art and its Problems) In recent years, thermal transfer materials have been widely used in facsimile machines, word processors, computer terminal printers, and the like. A typical thermal transfer material is a thin plastic film with a layer of thermal transfer ink on it, and when applied to a thermal printer, the thermal transfer ink is transferred onto receiving paper, creating a clear transferred image. For general office use, currently available thermal transfer materials are considered to be sufficient for the purpose. However, thermal transfer materials have also come into widespread use in label printers used in logistics and manufacturing plants. Particularly in manufacturing factories, transfer images are increasingly required to have heat resistance of 100 to 120° C. or higher due to the environment, the type of filler, post-processing issues, etc. However, the reality is that there is currently no thermal transfer material on the market that can form a transferred image that satisfies heat resistance characteristics of 100 to 120°C or higher. (Means for Solving the Problems) The present inventors have discovered that when thermal transfer ink is formed using a specific substance having a melting point of 120°C or higher, the thermal transfer material has high heat resistance, for example, can withstand temperatures of 100 to 120°C or higher. The present inventors have discovered that the following can be obtained, and have completed the present invention. That is, the present invention is shown in FIG. 1 (cross-sectional view of thermal transfer material).
As shown in the figure, in a thermal transfer material having a thermal transfer ink layer 1 on the surface of a plastic film 2 with a thickness of 2 to 15 μm and a heat-resistant protective layer 3 on the back side, the thermal transfer ink is (a) a fatty acid amide or a fatty acid imide having a melting point of 120°C or higher. , and (b) a polyamide resin or vinyl resin having a melting point of 100° C. or higher. Fatty acid amides that can be incorporated into the thermal transfer ink of the present invention have a melting point of 120° C. or higher, and include methylene bis-stearamide and ethylene bis-stearamide. A more specific example is Armowax EBS commercially available from Armor Company. Similarly, the fatty acid imide must have a melting point of 120 DEG C. or higher, and for example, Akrawax-C, commercially available from Glyco Chemical Company, is suitable as the fatty acid imide. Fatty acid amide and imide may be used alone or in combination. Polyamide resin and vinyl resin also have a melting point of 100℃
or more is required. Examples of polyamide resins include polymerized fatty acid polyamide resins, and a more suitable example is Tomide #1310 commercially available from Fuji Kasei Kogyo Co., Ltd. Examples of vinyl resins include vinyl chloride resin, vinyl acetate resin, and ethylene vinyl acetate copolymer. EVA-150 commercially available from Mitsui Polychemical Co., Ltd. is particularly suitable. In the composition of thermal transfer ink, when the ratio of (a) fatty acid amide or fatty acid imide with a melting point of 140°C to (b) polyamide resin or vinyl resin is in the range of 1:1 to 5:1, the most appropriate resin ratio is 1:1. 1
If the amount increases, thermal transferability becomes extremely poor. Wax ratio of fatty acid amide and fatty acid imide is 5:1
If the amount increases, the coated thermal transfer ink will peel off more easily than the film, especially at low temperatures in winter (10
(°C or below), ink flakes off from the film during printer operation and adheres to the printer head or image receiving paper, causing various troubles. The thermal transfer ink contains a coloring agent in addition to the above components. The coloring agent is usually carbon black, but other coloring agents such as cyanine blue, lake red, carmine red, cyanine green, Hanser yellow, and permanent yellow may be used if desired. The content of the colorant in the ink is usually 3 to 30% by weight, preferably 5 to 20% by weight. The thermal transfer ink is dissolved in a solvent and applied onto the plastic film 2. Examples of solvents that can be used include toluene, ethanol, isopropyl alcohol, ethyl acetate, butyl acetate, and the like. The coating layer of thermal transfer ink is a dry solid layer.
A coating layer of 1.5μ to 5.0μ is appropriate, and the optimal coating layer is determined by each printer and the type of image receiving paper (for example, for the Kanzaki thermal printer K-8108, a thermal transfer ink coating layer of 3.7μ to 4.0μ is optimal. ). The plastic film 2 and heat-resistant protective layer 3 used in the present invention may be those commonly used in conventional heat-sensitive transfer materials. Examples of the plastic film 2 include polyethylene terephthalate, polyester film, polycarbonate film, and triacetyl cellulose film having a thickness of 2 to 15 μm, but polyethylene terephthalate is particularly preferred because it has good heat resistance and can yield an extremely thin film. It is. The heat-resistant protective layer 3 is constructed for the purpose of preventing the plastic film from causing a fusion phenomenon (stacking) on the thermal head and causing problems in the running of the printer, and is preferably described in Japanese Patent Application Laid-Open No. 1983-1993 by the present inventors. Examples include a combination of nitrocellulose and cellulose acetate described in Japanese Patent No. 190390. The mixing ratio of nitrocellulose and cellulose acetate and the coating layer (as a dry solid content) are determined by the printer model. (Example) The present invention will be described below with reference to Examples. Example 1 A thermal transfer ink of the present invention was prepared by the following method. Ingredients by weight Armowax EBS 20.0 Tomide #1310 10.0 Carbon Black 8.0 Ethanol 20.0 Toluene 42.0 100.0 The raw materials in the above formulation were milled in a ball mill, sand mill,
Thermal transfer ink is obtained by kneading using an attritor, etc., and the dry solid content is 1.5 to 1.5% using a Mayer bar film coater.
A thermal transfer material (thermal transfer ink layer only) was obtained by applying a 5.0μ coating layer to a plastic film. Example 2 A thermal transfer ink of the present invention was prepared as follows. Ingredient parts by weight Akurawax-C 20.0 EVA-150 5.0 Carbon black 5.0 Toluene 70.0 100.0 The raw materials of the above formulation were produced and coated in the same manner as in Example 1 to obtain a thermal transfer film (thermal transfer ink layer only). Comparative Example 1 A conventionally formulated thermal transfer ink was prepared as follows. Ingredient parts by weight Carnauba wax 40.0 Ester gum 5.0 Parafine wax 35.0 Carbon black 20.0 100.0 By melting and dispersing each raw material in the above recipe at 90 to 100°C and kneading it using a three-roll, sand mill, attritor, etc. Thermal transfer ink is obtained, 90 ~
A thermal transfer film (thermal transfer ink layer only) was obtained by coating a plastic film with a coating layer of 1.5 μm to 5.0 μm at 110° C. using a flexographic film coater. Test Example A thermal transfer film was obtained by coating the above thermal transfer material (thermal transfer ink layer only) with a heat-resistant protective ink having the following composition in a coating layer of 0.2 μm to 1.5 μm using a Meyer bar film coater. Heat-resistant protective ink Nitrocellulose SS1/4 12.0 parts by weight Cellulose acetate L-20 3.0 Ethanol 25.0 Ethyl acetate 10.0 Butyl acetate 10.0 Nitropropane 40.0 100.0 The thermal transfer film obtained as above was mounted on Kanzaki Thermal Printer K-8108. The heat resistance of the printed images was as shown in Table 1, proving the effectiveness of the present invention. 【table】

[Brief explanation of drawings]

FIG. 1 is a sectional view of the heat-sensitive transfer material of the present invention. In the figure, 1 is a carbon ink layer, 2 is a plastic film, and 3 is a heat-resistant protective layer.

Claims (1)

[Scope of Claims] 1. A thermal transfer material having a thermal transfer ink layer 1 on the surface of a plastic film 2 with a thickness of 2 to 15 μm and a heat-resistant protective layer 3 on the back surface, in which the thermal transfer ink is (a) a fatty acid amide having a melting point of 120° C. or higher; or fatty acid imide,
and (b) a heat-sensitive transfer material containing a polyamide resin or vinyl resin with a melting point of 100°C or higher. 2. The thermal transfer material according to item 1, wherein the blending ratio of components (a) and (b) is 1:1 to 5:1. 3. The thermal transfer material according to item 1, wherein the thermal transfer ink layer has a thickness of 1.5 to 5.0μ. 4. The thermal transfer material according to item 1, wherein the thermal transfer ink further contains a colorant. 5. The heat-sensitive transfer material according to item 1, wherein the heat-resistant protective layer contains a mixture of nitrocellulose and cellulose acetate.