JPH0482789A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To obtain a thermal transfer recording medium from which an image having high transferability during printing and also superb abrasion and scratch resistance be obtained by providing a peel-off layer consisting mainly of an ethylene-vinyl acetate copolymer resin and lubricant. CONSTITUTION:The peel-off layer of the thermal transfer recording medium is composed mainly of ethylene-vinyl acetate copolymer resin (EVA) and lubricant. The content of vinyl acetate in EVA should preferably be 19 to 30wt.%. The EVA which deviates from this range becomes less compatible with the lubricant and also becomes deteriorated in terms of the abrasion and scratch resistance of a transferred image. The ratio of the contents of EVA and the lubricant is 1 to 50/99 to 50, and should preferably be 3 to 30/97 to 90. The EVA which forms the surface layer of the transferred image is highly compatible with the lubricant. Thus the coagulative force of the lubricant surface layer is increased by the EVA and therefore, the surface is highly resistant to scratches and rubbing such as by a pan scanner test. In addition, the surface layer, being of a lubricant property, is protected against fouling caused by rubbing such as by a carton box test.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a thermal transfer recording medium for performing thermal transfer recording on recording paper using the heat-melting properties of an ink layer, and is applicable to printers such as computers, word processors, etc. It can also be applied to code printers, etc.

[Conventional technology]

Thermal transfer recording media generally consist of either (1) a heat-melt ink layer provided on a support, or (2) a release layer and a heat-melt ink layer laminated in sequence on a support. It has become.

Many such thermal transfer recording media (hereinafter sometimes referred to as "recording media") have been proposed, and some of them are listed below. (1) An ink layer made by dispersing resin (including ethylene-vinyl acetate copolymer) and wax in an insoluble solvent (resin and wax exist independently in the form of particles) (JP-A-1-291986) (2) A polar wax is used as a release layer, and an ethylene-vinyl acetate copolymer (rEVA hereinafter) is used in the release layer.
(sometimes referred to as J) (Japanese Patent Application Laid-Open No. 1-27
8389), (3) an ink layer containing an elastomer (Japanese Unexamined Patent Publication No. 1-247194), (4) a transfer layer having a fixing layer compatible with the thermal transfer latent (
JP-A No. 64-49672).

However, although the recording medium described in (1) above provides a transferred image with relatively high resolution, the resin and wax are not compatible with each other in the ink layer and exist independently in the form of particles. There is a tendency that the areas where the resin particles are exposed have poor slippage, and the areas where the wax particles are exposed have poor adhesion to the transfer target. The recording medium of (2) has relatively good ink transfer properties, but tends to have poor abrasion resistance and scratch resistance.

The recording medium of (3) has the advantage of having a simple layer structure, but since the uppermost portion of the transferred image contains carbon, it tends to have poor abrasion resistance.

Further, although the recording medium of (4) has excellent abrasion resistance, since the transfer paper is a special paper, it is expensive and tends to lack the appearance of paper.

[Problems to be Solved by the Invention] The present invention provides a thermal transfer recording medium that has excellent transferability during printing and provides a transferred image with excellent abrasion resistance and scratch resistance.

The present inventors have confirmed that the above object can be achieved if the release layer is formed of a specific composition.

The present invention has been achieved thereby.

The present invention will be explained in more detail below.

As the support used in the present invention, heat-resistant plastic films such as polyester, polycarbonate, triacetylcellulose, nylon, and polyimide, cellophane, parchment paper, condenser paper, etc. can be used, and if necessary, the heat head of the support can be used. A heat-resistant layer made of silicone resin, fluorine resin, polyimide resin, epoxy resin, phenol resin, melamine resin, cellulose resin, etc. may be provided on the surface in contact with the resin.

The appropriate thickness of the support is about 3 to 10 thick.

The release layer is ethylene-vinyl acetate copolymer resin (EVA)
and a lubricant as the main components, and its thickness is 0.2 to 3.
OIa is preferably 0.5-1.5 μm.

The vinyl acetate content in EVA is preferably 19-19.
It is 30% by weight (according to JIS K 6730). EVA that deviates from this range has poor compatibility with lubricants,
Furthermore, the abrasion resistance and scratch resistance of the transferred image become inferior.

Lubricants include natural waxes such as carnauba wax, candelilla wax, beeswax, wood wax, montan wax, spermaceti wax, paraffin wax, microcrystalline wax, and oxidized wax.

Synthetic waxes such as polyethylene wax, margaric acid, lauric acid, mystylic acid, palmitic acid,
Examples include higher fatty acids such as stearic acid, fromene acid, and behenic acid and their metal salts, higher alcohols such as stearyl alcohol and behenyl alcohol, esters such as fatty acid ester of sorbitan, and amides such as stearinamide and oleinamide.

The EVA/lubricant ratio is 1-50/99-50, preferably 3-30797-90.

The heat-melting ink layer is a conventionally known heat-melting layer.
The main components are colorants, waxes, and resins, and the thickness is about 0.5 to 5 tiles, preferably 1 to 3 thick.

The colorant is appropriately selected from conventionally known dyes and pigments. As waxes, those used for the above-mentioned release layer can be used.

Examples of resins include polyamide-based, polyester-based, polyurethane-based, vinyl chloride-based, cellulose-based, petroleum-based, styrene-based, butyral-based, and phenol-based resins, as well as ethylene-vinyl acetate copolymers and ethylene-acrylic resins. Examples include resin.

The ratio of colorant/wax/resin is 5 to 50/30
9075-50, preferably 10-3 (1150-80
It is 15-30.

In addition to these, the ink layer also contains small amounts of known plasticizers and oils such as fatty acid esters, glycol esters, phosphate esters, and epoxidized linseed oil (30
% by weight or less) may be added.

Actually, in order to produce the thermal transfer recording medium of the present invention, it is sufficient to prepare a release layer forming liquid and a heat-melting ink layer forming liquid, respectively, and sequentially apply these to a support.

By using the thermal transfer recording medium of the present invention, a high-quality transferred image can be obtained without any inconvenience, but this effect is due to the fact that EVA forming the surface layer of the transferred image has good compatibility with the lubricant. By increasing the cohesive force of the layer, it is resistant to scratching and rubbing as in the pan scanner test, and the surface layer has lubricant properties, making it slippery and resistant to large scratches as in the cardboard test. Seem.

〔Example〕

All percentages and parts herein are based on weight.

Example I A mixture consisting of 1 part EVA (vinyl acetate content 28%) 9 parts carnauba wax (melting point 83°C) 90 parts methyl ethyl ketone
A release layer forming solution was prepared by dispersing in a ball mill for 2 hours.

This was applied onto a polyester film (support) having a thickness of about 4.52 parts using a wire bar, and was dried to form a release layer having a thickness of about 1 μm. Carbon black 3 parts Candelilla wax 10 parts Styrene-acrylic copolymer resin 2 parts Toluene
A thermal transfer recording medium was prepared by dispersing a mixture of 85 parts in a ball mill for 12 hours, applying an ink layer forming liquid using a wire bar, and drying to form a heat-melting ink layer about 2.5 parts thick. Ta.

Example 2 EVA (vinyl acetate content 20%) as release layer 3
A thermal transfer recording medium was prepared in exactly the same manner as in Example 1 except that a mixture consisting of 1 part paraffin hook (melting point 65-66 DEG C.) 7 parts methyl ethyl ketone 90 parts was dispersed in a ball mill for 12 hours.

Comparative Example 1 A comparative thermal transfer recording medium was prepared in exactly the same manner as in Example 1, except that EVA with a vinyl acetate content of 5% was used in the release layer.

Comparative Example 2 Vinyl acetate content is 40% as EVA in release layer
A comparative thermal transfer recording medium was prepared in exactly the same manner as in Example 1, except that .

A commercially available Tsuku-coat thermal transfer printer (BC-8MKI manufactured by Autonics Co., Ltd.) uses these four types of thermal transfer recording media.
I) was given an energy of 15.2n+J/mm" to print on a transfer material (surface-treated mirror-coated paper with smooth characters for about 4000 seconds, manufactured by Kanzaki Paper Co., Ltd.). In the test to examine the friction properties, cardboard paper was used as the transfer target.The results are shown in Table 1.

Table 1 (Note) Transferability: Evaluation was made based on whether the barcode part was clearly printed.

○ means that the barcode portion is clearly printed and transferred.

× means that the barcode portion is printed unclearly, and some barcodes are not partially transferred.

Friction resistance: Place a 4cm x 7cm square Danbo (cardboard test) board on the barcode area and apply a load of 500gf.

The same spot was rubbed 100 times using a love tester for evaluation.

The barcode part of O is almost clean.

This means that it can be read with a barcode scanner without any problems.

× means that the barcode part is quite dirty and difficult to read with a barcode scanner.

Abrasion resistance: Tracing the same spot on a barcode (pen scanner test) printed with a pen scanner 150 times, assuming the number of readings is n times, n150 x 100 (%)
It was evaluated by applying the following formula. 100% means that everything could be read.

Scratch resistance: Evaluation was made based on whether or not the image was missing when scratched 5 times with a fingernail. O means no omission, and X means omission.

〔Effect of the invention〕

As is clear from the description of the Examples, the intended purpose can be fully achieved by using the thermal transfer recording medium of the present invention.

Claims (3)

[Claims] (1) A thermal transfer recording medium in which a release layer is provided on a support and a heat-melt ink layer is provided thereon, characterized in that the release layer mainly contains an ethylene-vinyl acetate copolymer resin and a lubricant. thermal transfer recording media. (2) The thermal transfer recording medium according to claim 1, wherein the mixing ratio of the ethylene-vinyl acetate copolymer resin and the lubricant is 1-50/99-50. (3) The thermal transfer recording medium according to claim 1 or 2, wherein the vinyl acetate content of the ethylene-vinyl acetate copolymer resin is 19 to 30% by weight.