JPH03239589A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To prevent the generation of the so-called ghost such that the previous printing pattern is raised in a printing body on and after the second time by adding a non-heat-meltable particle to an ink layer. CONSTITUTION:As the non-heat-meltable particle contained in an ink layer, an inorg. particle such as a titanium oxide particle, a magnesium oxide particle or a metal powder and an org. particle mainly composed of a thermosetting resin such as a polystyrene resin or a benzoguanamine resin are designated. The particle may have any shape, but a spherical particle is pref. used and the pref. particle size thereof is 4 - 20 mum and the addition amount thereof is pref. 5 - 40 vol. % with respect to the total amount of heat-meltable ink. The ink layer is formed on a support by applying the components forming the ink layer on the support by a hot melt method or a solvent coating method.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a thermal transfer recording medium that can be printed multiple times, and more specifically, the present invention relates to a thermal transfer recording medium that can be printed multiple times. The present invention relates to a thermal transfer recording medium that prevents.

[Conventional technology]

Thermal transfer recording has recently become widespread because the device is lightweight, compact, noiseless, has excellent operability and maintainability, and can use plain paper. However, conventionally used thermal transfer recording media have the disadvantage that once they are used, the ink in the heating section bleeds through, making it impossible to use them repeatedly and resulting in high printing costs.

In order to improve these drawbacks, Japanese Patent Application Laid-Open No. 57-366
No. 98 and Japanese Unexamined Patent Publication No. 59-96992 disclose that by providing an adhesive layer between the base film and the ink layer,
A thermal transfer recording medium has been proposed in which the ink is gradually peeled off each time printing is performed, without being transferred all at once, so that it can be used repeatedly. In addition, other thermal transfer recording media based on the same idea were published in JP-A-59-21.
This method has been proposed in JP-A No. 8279, JP-A-63-178081, JP-A-64-77578, and the like. However, when such a method is used, the thickness of the ink layer in the area heated by -degrees (printed area) is thinner than that in the area that is not heated (unprinted area), so the heat capacity of the printed area is becomes smaller. Therefore, when the next printing is performed across the printed area and the unprinted area, due to the difference in heat capacity, the amount of ink transferred to the printed area is larger than that of the unprinted area, and shading occurs in the printed area. In particular, when printing a graphic pattern such as halftone dots, a so-called ghost occurs in which a previously printed pattern stands out within the graphic pattern, making accurate recording impossible.

[Problem to be solved by the invention]

An object of the present invention is to provide a thermal transfer recording medium that can be printed many times and does not cause so-called ghosts in which the previous print pattern stands out in the print after the second printing.

[Means to solve the problem]

By using a thermal transfer recording medium in which the ink layer contains non-thermofusible particles, the present invention enables recording without the occurrence of ghosts in the second and subsequent printings.

That is, the present invention provides a thermal transfer recording medium in which an ink layer is provided on a support and is transferred to another layer by being melted or softened by heat, in which the ink layer contains non-heat-fusible particles having a particle diameter of 4 μm to 20 μm. The present invention provides a thermal transfer recording medium characterized by the following.

The present invention will be explained in detail below.

The thermal transfer recording medium of the present invention is provided with an ink layer on a support that is melted or softened by heat and transferred to another layer, and the ink layer contains non-thermofusible particles.

The non-thermofusible particles contained in the ink layer include:
It may be either inorganic or organic.

Inorganic particles include titanium oxide, magnesium oxide, magnesium hydroxide, aluminum oxide, aluminum hydroxide, barium sulfate, verculite, perlite, acid clay, activated clay, diatomaceous earth, dolomite, mica, sericite, bentonite, kaolin, Examples include clay, talc, calcium carbonate, graphite, silica, nickel, aluminum, copper, iron, and other metal powders. Organic particles include polystyrene resin, benzoguanamine resin,
Mainly thermosetting resins include xylene resin, polyimide resin, urea resin, melamine resin, acrylic resin, epoxy resin, phenol resin, and silicone resin.

The shape of the non-thermofusible particles may be scale-like, amorphous, or spherical, but spherical particles are preferably used.

The particle size of the non-thermofusible particles is preferably 4 μm to 20 μm. In particular, it is preferable that the thickness be approximately the same as the thickness of the ink layer and within a range of ±20% with respect to the thickness of the ink layer. Therefore, the thickness of the ink layer is preferably changed depending on the size of the particles used. If the particle size is too small compared to the ink thickness, the effect of preventing ghosting may not be sufficient, and if particles exceeding 20 μm are used, the ink layer becomes too thick, which may reduce thermal sensitivity. , undesirable.

The amount of the non-thermofusible particles added is preferably 5 to 40% by volume based on the total amount of the thermofusible ink, particularly preferably,
It is 10 to 30% by volume. If it is less than 5% by volume, there may be no ghost prevention effect, and if it exceeds 40% by volume, the print quality may deteriorate.

In addition to the non-thermofusible particles, the ink layer of the thermal transfer recording medium of the present invention contains a low melting point resin and a colorant, and if necessary, additives such as polymers, surfactants, and softeners. Contains.

Low melting point resins include synthetic waxes such as paraffin wax, microcrystalline wax, ceresin wax, oxidized wax, ester wax, osikerite wax, and polyethylene wax, or natural waxes such as beeswax, carnauba wax, spermaceti wax, wood wax, and montan wax. Wax is preferably used. The amount added is preferably 10 to 70% by volume based on the total amount of ink.

As the colorant, carbon black, phthalocyanine pigments, azo pigments, other organic pigments, inorganic pigments, dyes, etc. are used. The amount added is preferably 10 to 40% by volume based on the total amount of ink.

Examples of polymers include ethylene-acrylic acid copolymer, ethylene-alkyl acrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl acetate-unsaturated acid copolymer, and saponified ethylene-vinyl acetate copolymer. , ethylene-based copolymers such as ethylene-vinyl acetate-maleic anhydride copolymer are preferably used, and in addition, polyamide-based resins,
Polyester resin, epoxy resin, polyurethane resin, durable resin, vinyl chloride resin, cellulose resin, polyvinyl alcohol resin, petroleum resin, phenol resin, styrene resin, natural rubber, styrene butadiene Examples include elastomers such as rubber, isoprene rubber, chloroprene rubber, butyl rubber, and butadiene rubber. The amount added is 5 to 2 to the total amount of ink.
0% by volume is preferred.

As the lubricant, polyhydric alcohol esters, higher alcohols, higher fatty acids, fluorocarbons, higher aliphatic amides, etc. are used.

As the surfactant, one selected from various anionic, cationic, nonionic, and amphoteric surfactants is used.

Softeners include organic acid esters such as phthalate esters and adipic esters, phosphate esters, epoxies, other plasticizers, oily substances such as mineral oil, vegetable oil, animal oil, and castor oil, liquid rubber, and Vaseline and other room temperature liquid or semi-solid substances are used.

The support used in the present invention may be any heat-resistant film, and includes, for example, plastic films such as polyester, polyamideimide, nylon, and polyimide, and papers such as capacitor paper and glassine paper.

The thickness of the support is preferably in the range of 1 to 20 μm. Thin ones are easy to tear, and if the thickness exceeds 20 um, excessive energy is required to perform thermal transfer, which is not practical.

The thermal transfer recording medium of the present invention as described above can be obtained by applying components for forming an ink layer onto a support by a hot melt method, a solvent coating method, or the like. The thickness of such an ink layer is suitably 4 to 20 μm.

[Effect]

The thermal transfer recording medium of the present invention can prevent the occurrence of ghosts by including the non-thermally fusible particles in the ink layer, and this is presumed to be due to the following reasons.

That is, in the first printing, some of the non-thermofusible particles in the ink layer of the heated portion are transferred to the paper, but some remain on the film side, which is the support of the thermal transfer recording medium. By the way, the size of the non-thermo-fusible particles is almost equal to the thickness of the ink layer, so in the second and subsequent printings, the non-thermo-fusible particles remaining on the film side will overlap the ink surface of the first heated part and the paper. Prevents close contact with. Therefore, it functions to prevent thermal conductivity and ink transferability during printing. Therefore, it is possible to offset the difference in ink transfer amount due to the difference in heat capacity between the ink layer in the unheated part and the ink layer in the heated part in the first printing, eliminating the difference in shading in printing from the second printing onwards, and preventing the occurrence of ghosts. It is thought that this can be prevented.

〔Example〕

Next, the present invention will be explained with reference to examples. Note that all percentages expressed are volume %.

Example 1 A thermal transfer recording medium was prepared by dissolving an ink with the following composition in toluene on a 6.0 μm thick polyester film, applying it with a wire bar, drying and removing the toluene, and providing a 10 μm thick ink layer. did.

Paraffin wax (5P-0145 manufactured by Nippon Seikasha) 40% carbon black (Printex 90 manufactured by Degussa) 20% ethylene-vinyl acetate copolymer (MFR = 400. Vinyl acetate content = 28 wt%) 2
0% benzoguanamine resin particles Particle size: 9 μm (Eposta-GP90 manufactured by Nippon Shokubai Kagaku Co., Ltd.) 20% Example 2 Same as Example 1 except that the composition of the hot-melt ink layer of Example 1 was replaced with the following. A thermal transfer recording medium of the present invention was produced in this manner.

Paraffin wax (manufactured by Nippon Seiren Co., Ltd. 5P-0145) Carbon black (manufactured by Degussa Corporation Printex 90) 40% 20% Ethylene-vinyl acetate copolymer (MFR = 150, vinyl acetate 7L/content = 33 wt%
) 20% Cross-linked polystyrene resin particles Particle size: 8 μm (Sumitomo Chemical Co., Ltd. Fine Var 5PA) 20% Comparative Example 1 Example 1 except that the composition of the hot-melt ink layer of Example 1 was replaced with the following. A thermal transfer recording medium was produced in the same manner as described above.

Paraffin wax (manufactured by Nippon Seirosha 5P-0145) 60% carbon black (manufactured by Degussa Corporation Printex 90) 20% ethylene-vinyl acetate copolymer (MFR = 150, vinyl acetate content = 19 wt%) 2
0% Comparative Example 2 A thermal transfer recording medium was produced in the same manner as in Example 1, except that the composition of the heat-melting ink layer in Example 1 was changed to the following.

Paraffin wax (manufactured by Nippon Seirosha 5P-0145) 40% carbon black (manufactured by Degussa Corporation Printex 90) 20% ethylene-vinyl acetate copolymer (MFR = 330, vinyl acetate content = 25 wt%) 2
0% benzoguanamine resin particles Particle size: 2 μm (Eposter MS manufactured by Nippon Shokubai Kagaku Co., Ltd.) 20% Comparative Example 3 The composition of the hot-melt ink layer of Example 1 was replaced with the following, and an ink layer with a thickness of 25 μm was provided. A thermal transfer recording medium was produced.

Paraffin wax (5P-0145 manufactured by Nippon Seirosha) 40% carbon black (Printex 90 manufactured by Degussa) 20% ethylene-vinyl acetate copolymer (VFR = 150, vinyl acetate content = 19 wt%) 2
0% benzoguanamine resin particles Particle size: 25 μm (Nippon Shokubai Kagaku Co., Ltd. Epostorum) Thermal transfer recording media of Example 1, Example 2, Comparative Example 1, Comparative Example 2, and Comparative Example 3 obtained as above 20% using thermal transfer paper (
A commercially available word processor (manufactured by Fujitsu, Oasis 30LX)
), and the printing was evaluated at an energy of 0.30 mj/dat. Printing was repeated twice, and the first printing pattern used the kanji ``kanpa'', and the second printing pattern used the same part as the first printing, and printed a shaded pattern. The clarity of the character "kan°°" in the second pattern was visually judged and evaluated as a ghost. Thermal sensitivity was also evaluated. In addition, the printing characteristics of multiple times are 5
Evaluation was made by repeatedly printing. The results are shown in Table 1.

Evaluation in Table 1 Ghost: No generation of O Thermal sensitivity: O Good Multiple printing performance: Possible x Occurrence X Poor x Impossible As shown in Table 1, Examples 1 and 2 of the present invention have no There is no occurrence, the sensitivity is good, and it is possible to print multiple times.

〔Effect of the invention〕

According to the present invention, by containing particles in the ink layer having a particle size equivalent to the thickness of the ink layer, it is possible to provide a thermal transfer recording medium that can be used many times without generating ghosts or decreasing sensitivity. can.

Claims (1)

[Scope of Claims] 1. In a thermal transfer recording medium comprising an ink layer on a support that is melted or softened by heat and transferred to another, the ink layer has non-thermo-fusible particles having a particle size of 4 μm to 20 μm. A thermal transfer recording medium characterized by containing. 2. The thermal transfer recording medium according to claim 1, wherein the non-thermofusible particles have a particle diameter that is approximately the same as the thickness of the ink layer.