JPH02238993A - Thermal transfer ink sheet - Google Patents

Abstract

PURPOSE:To improve repeatability in the case of using a thermal transfer ink layer containing a wax having urethane linkage by a method wherein said ink layer of a thermal transfer ink sheet that can be repeatedly used contains the wax having urethane linkage, and an intermediate adhesive layer contains a vinyl chloride-vinyl acetate copolymer. CONSTITUTION:A thermal transfer ink sheet is formed by successively laminating an intermediate adhesive layer 2 and an ink layer 3 on a substrate 1 and capable of being repeatedly used. The ink layer 3 of the thermal transfer ink sheet contains a wax having urethane linkage, and the intermediate adhesive layer 2 contains a vinyl chloride-vinyl acetate copolymer. In this construction, a stable and satisfactory repeatability can be realized even when the wax having urethane linkage is contained in the thermal transfer ink layer 3. The thermal transfer ink sheet having a favorable film forming capacity given by the ink layer containing the wax having urethane linkage can be repeatedly used.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Prior art (Figure 4) Means for solving the problem to be solved by the invention (Figure 1) Working example (a) 1 Description of Examples (Figures 2 and 3) (B) Description of Other Examples Effects of the Invention [Summary] Regarding a thermal transfer ink sheet that can be used by repeated transfers, a thermal transfer ink containing a wax having a urethane bond. A reusable thermal transfer ink sheet in which an intermediate adhesive layer and an ink layer are sequentially laminated on a base material with the aim of improving the repeatability when using a layer, and the ink layer contains a wax having a urethane bond. The intermediate adhesive layer contains a vinyl chloride/vinyl acetate copolymer. [Industrial. Field of Application] The present invention relates to a thermal transfer ink sheet that can be repeatedly used for transfer, and more particularly to a repeatedly usable thermal transfer ink sheet that has an improved intermediate adhesive layer that adheres an ink layer to a base material. A thermal transfer recording device is a device in which a thermal transfer ink sheet is provided between a thermal head and a sheet of paper, and the thermal transfer ink on the thermal transfer ink sheet is melted or sublimated by applying heat from the thermal head and transferred onto the sheet of paper. In recent years, thermal transfer ink sheets that can be used repeatedly have been provided on the market in place of one-time thermal transfer ink sheets that consume an ink layer in one use. In such a heat transfer ink sheet that can be used repeatedly, maintaining sufficient adhesion with the ink layer is important.
This is necessary to ensure repeated use. [Conventional technology] Figure 4 is an explanatory diagram of the conventional technology. As shown in FIG. 4, a reusable thermal transfer ink sheet is constructed by forming an intermediate adhesive layer 2 on a base material I made of polyester resin, and forming a thermal transfer ink layer 3 on this intermediate adhesive layer 2. It will be done. Base material 1 of thermal transfer ink sheet
On the side, the thermal head HD has a thermal transfer ink layer of 3g!
The printing press PP is located at J, and the ink material of the thermal transfer ink layer 3 oozes out due to the heating of the thermal head hd, and transfer is performed. This intermediate adhesive layer 2 is an essential component of a heat transfer ink sheet that can be used repeatedly. In other words, this intermediate adhesive layer 2 firmly adheres the base material 1 and the ink layer 3, thereby preventing the ink layer from peeling off as in conventional one-time thermal transfer ink ribbons that consume the ink layer in one application. However, the ink material consisting of dye and wax gradually oozes out from the gaps between the fillers in the ink layer and is transferred, making it possible to print repeatedly. Therefore, the intermediate adhesive layer 2 is required to have good flexibility and adhesive properties under the environmental conditions of 10° C. to 35° C. (winter to summer) considered during actual printing. In this thermal transfer ink sheet, the thermal transfer ink layer 3 is a patent application in which a low melting point material consisting of fatty acid amide wax and paraffin wax, a dye, and carbon plank as a filler are coated and dried using an organic solvent. This is disclosed in Publication No. 56-89984, etc. In Patent Application Publications No. 49998/1980 and Publication No. 74892/1989, etc., polyamide resin is used as the material for the intermediate adhesive layer 2, which is compatible with or has adhesive strength with fatty acid amide wax, which is the ink layer material. and,
It has been proposed to use a mixture of the above-mentioned base material 1 and a polyester resin with adhesive strength to increase the adhesive strength to both the ink layer and the base material. (Problems to be Solved by the Invention) By the way, three thermal transfer ink layers made of wax having at least urethane bond are disclosed in Japanese Patent Application Publication No. 142690/1982 and Japanese Patent Application Publication No. 1987-1989. It is disclosed in Japanese Patent No. 144996. When such a material is made of urethane-bonded wax, the thermal transfer ink layer 3 has a high ability to form a film, is not brittle even after use, forms a strong film, and is easily transferred to recording paper. It has the unique advantage of preventing background smudges.When this urethane-bonded wax is used for the thermal transfer ink layer 3, the intermediate adhesive layer 2 can be made of polyamide resin, which has been conventionally proposed. Then, since the compatibility (adhesive force) between the polyamide resin and the urethane-bonded wax is low, the effectiveness as the intermediate adhesive layer 2 is reduced, resulting in a problem that the repeatability is deteriorated. An object of the present invention is to provide a thermal transfer ink sheet that can improve the repeatability when a thermal transfer ink layer containing a wax having urethane bonds is used. (Means for solving the problem) Figure 1 shows the present invention. As shown in FIG. 1, the present invention provides a reusable thermal transfer ink sheet in which an intermediate adhesive layer 2 and an ink layer 3 are sequentially laminated on a base material 1, in which the ink layer 3 is The intermediate adhesive layer 2 contains a wax having a urethane bond, and the intermediate adhesive layer 2 contains a vinyl chloride/vinyl acetate copolymer. It was discovered that vinyl/vinyl acetate copolymer has good compatibility, and the intermediate adhesive layer 2 contains the vinyl chloride/vinyl acetate copolymer to bond with the thermal transfer ink layer 3 made of wax having urethane bonds. [Example] (a) Description of one example The thermal transfer ink sheet according to the present invention uses a polyester resin film with a thickness of 6 pm as the base material 1, and on this film base material 1, a polyester 100 parts by weight of resin (manufactured by Hitachi Chemical Polymer) and vinyl chloride/vinyl acetate copolymer (
A resin mixed with 40 parts by weight (manufactured by Nippon Kayaku) was coated to a thickness of 2 am to form the intermediate adhesive layer 2. Further, on the intermediate adhesive layer 2, as a thermal transfer ink layer 3, 25 parts by weight of dye (manufactured by Nippon Kayaku), 50 parts by weight of wax having urethane bonds (urethane wax, manufactured by Nippon Oil & Fats), and paraffin wax (manufactured by Nippon Kayaku) are added. By applying an ink coating liquid prepared by dissolving and dispersing 25 parts by weight of 25 parts by weight of fine wax (made from fine wax) and 10 parts by weight of fine powder of carbon black (manufactured by Tokai Carbon) in an organic solvent such as acetone, and drying it, a thick A thermal transfer ink sheet having a length of 101 m and which can be repeatedly transferred was constructed. The thermal transfer ink sheet formed in this way was repeatedly printed on the same spot with a recording energy of 35 mJ/mm'', and the first transfer density (0.D.) = 1.2.
3rd, 5th, and 71st transfer density ratios were 40%. Therefore, even in the fifth transfer, 40% of the transfer density was changed from the first transfer, and it was proved that the transfer density could be repeated at least five times. Also, the first transfer density was 1.23, which was appropriate.
It was demonstrated that the vinyl chloride/vinyl acetate copolymer properly adhered to the wax having urethane bonds in the thermal transfer ink layer 3. Regarding the above example, in order to further examine the composition of the intermediate adhesive layer 2, 0 to 85 parts of vinyl chloride/vinyl acetate copolymer was added to 100 parts by weight of the polyester resin.
A reusable thermal transfer ink sheet is constructed using an intermediate adhesive layer 2 formed by coating a resin mixed in a range of parts by weight to a thickness of 2 μm, and a recording energy of 35 μm is used.
mJ/mm", the same location was repeatedly printed. Figure 2 is a first transfer density characteristic diagram of this example, and the horizontal axis shows vinyl chloride/acetic acid relative to 100 parts by weight of polyester resin in intermediate adhesive layer 2. Addition of vinyl copolymer liF
(parts by weight), and the vertical axis shows the first transfer density (0. D.
). Moreover, FIG. 3 shows the fifth example of the related embodiment.
This is a characteristic diagram of the 1st/1st transfer density ratio, where the horizontal axis shows the amount (parts by weight) of the vinyl chloride/vinyl acetate copolymer added to 00 parts by weight of the polyester resin in the intermediate adhesive layer 2.
, and the 5th/1st transfer density ratio (%) is plotted on the vertical axis. The experimental results shown in Figure 2 revealed that when the amount of vinyl chloride/vinyl acetate copolymer added exceeds 60 parts by weight, the first transfer density decreases. This means that the amount added is 6
If it exceeds 0 parts by weight, the adhesive force with the wax having urethane bond of the thermal transfer ink layer 3 will be too strong, and the thermal transfer ink N
3 is thought to be difficult to transfer. or,
From the experimental results shown in Figure 3, it was found that a good transfer density ratio was achieved when the amount of vinyl chloride/vinyl acetate copolymer added was 20 parts by weight or more. This suggests that if the amount added is less than 20 parts by weight, the adhesive force between the thermal transfer ink layer 3 and the wax having urethane bonds is insufficient, and the thermal transfer ink layer 3 becomes easily transferred. From the above two points, the amount of vinyl chloride/vinyl acetate copolymer added is:
It is preferably in the range of 20 to 60 parts by weight per 100 parts by weight of the polyester resin. In addition, for comparison, experiments were conducted using a conventional intermediate adhesive layer to form a reusable thermal transfer ink sheet consisting of the ink layer made of wax having at least urethane bonds. That is, a resin prepared by mixing 100 parts by weight of a polyester resin and 50 parts by weight of a polyamide resin is coated to a thickness of 2 μm as an intermediate adhesive layer 2 on a polyester resin film base material 1 having a thickness of 6 μm, and then an ink layer is formed. 3, 25 parts by weight of dye (Nippon Kayaku ml) and wax having urethane bond (
5'0 parts by weight of urethane wax (manufactured by Nippon Oil & Fats), 25 parts by weight of paraffin wax (manufactured by Nippon Seiro), and 1O fine powder of carbon black (Tokai Carbon I1) as a filler.
An ink sheet was prepared by dissolving and dispersing parts by weight in an organic solvent such as acetone. Using this conventional ink sheet using an intermediate adhesive layer containing polyamide resin, printing was repeatedly performed on the same location at a recording energy of 35 mJ/mm''.The results showed that the first printing density was 1.3 (0.D. ) 5
The 1st/1st transfer density ratio was 20% or less. Even if the amount of polyamide resin added to intermediate adhesive layer 2 was changed, this value did not change. As can be seen from Figures 2 and 3, the experimental results for this conventional example show the same tendency as when no vinyl chloride/vinyl acetate copolymer is added to the intermediate adhesive layer 2 (0 parts by weight added). There is. Therefore, even if polyamide resin is mixed in the intermediate adhesive layer 2,
It was revealed that the adhesive strength of the thermal transfer ink layer 3 with the wax having a urethane bond could not be expected, and that the adhesive strength was poor. On the other hand, in the case of a mixture of vinyl chloride and vinyl acetate copolymer, even if even 1% of vinyl chloride and vinyl acetate copolymer is added, the adhesive layer 2 is repeatedly It was found to be effective in improving characteristics. Moreover, by changing the amount of vinyl chloride/vinyl acetate copolymer added in the intermediate adhesive layer 2, the first transfer density and the fifth transfer density can be adjusted.
The first transfer density ratio can be controlled arbitrarily. (b) Description of other examples When experiments were conducted by varying the amount of wax having urethane bonds added to the thermal transfer ink layer 3, the results showed the same tendency as in FIGS. 2 and 3. Therefore, it was proven that the adhesive effect of the vinyl chloride/vinyl acetate copolymer was exhibited regardless of the amount of wax having urethane bonds added to the thermal transfer ink layer 3. Furthermore, since polyester resin is used as the base material l, polyester resin is included in the intermediate adhesive layer 2 for adhesion to this, but materials compatible with other polyester resins may also be used. If the base material 1 is not a polyester resin, other well-known resin materials having compatibility with the materials of the base material 1 may be used. Although the present invention has been described above using examples, the present invention can be modified in various ways according to the gist of the present invention, and these are not excluded from the present invention. [Effects of the Invention] As explained above, according to the present invention, even if the thermal transfer ink layer 3 contains a wax having a urethane bond, stable and good repeatability can be achieved. This greatly contributes to making it possible to repeatedly use a thermal transfer ink sheet that has a good film formation by the ink layer containing the wax, and further contributes to reducing the running cost of such a thermal transfer ink sheet.

[Brief explanation of drawings]

FIG. 1 is a principle diagram of the present invention. FIG. 2 is a first transfer density characteristic diagram according to an embodiment of the present invention. FIG. 3 is a fifth/first transfer density ratio characteristic diagram according to an embodiment of the present invention. Figure 4 is an explanatory diagram of the conventional technology. In the figure, 1.1 base material, 2.-intermediate adhesive layer, 3.thermal transfer ink layer.

Claims (1)

[Claims] A reusable thermal transfer ink sheet in which an intermediate adhesive layer (2) and an ink layer (3) are sequentially laminated on a base material (1), wherein the ink layer (3) has a urethane bond. A thermal transfer ink sheet comprising wax, and the intermediate adhesive layer (2) comprising a vinyl chloride/vinyl acetate copolymer.