JPS62220387A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To obtain a thermal transfer recording medium capable of transferring images with high density, excellent uniformity and excellent abrasion resistance onto a recording paper, by using a coloring agent and a binder in a specified ratio and providing the coloring agent in a particulate form in a transfer layer. CONSTITUTION:A thermal transfer recording medium comprises a transfer layer comprising a binder and a color agent on a base, which coloring agent comprises a dye and/or a pigment and a thermoplastic resin having a softening point of 70-140 deg.C as main constituents. In the recording medium, the binder is used in an amount of 0.02-0.2pts.wt. per 1pts.wt. of the coloring agent, and the coloring agent is present in a particulate form in the transfer layer. If the softening point of the resin is lower than 70 deg.C, transferred images have poor abrasion resistance under high-temperature environments. If the softening point is higher than 140 deg.C, recording speed is lowered, and the useful life of a thermal head is shortened. If the amount of the binder used per 1pts.wt. of the coloring agent is less than 0.02pts.wt., the coloring agent is not easily supported on the base, and may drop out at the time of recording to cause ground contamination, whereas if the amount is more than 0.2pts.wt., the coloring agent is bound to the base so strongly that clear-cut property of a boundary between an image part and a non-image part becomes poor, and transfer recording can not be easily performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a thermal transfer recording medium for printing and recording on recording paper by utilizing the heat-melting properties of an ink layer.

[Prior Art] Conventionally, thermal transfer recording media have been known in which a transfer layer made of a heat-fusible substance such as paraffin wax, dyes, and pigments is provided on a support, but paraffin waxes have low mechanical strength. Therefore, there is a drawback that the abrasion resistance of the transferred image is poor.

In order to improve these drawbacks, methods have been taken such as adding thermoplastic resins or making the transfer layer as thin as possible, but in the former case, as the resin component increases, the adhesive force becomes stronger and transfer becomes difficult. , heat sensitivity worsens. The disadvantage of this type is that the uniformity of the transferred image becomes poor and the image density becomes low.

[Objective] An object of the present invention is to provide a thermal transfer recording medium that can provide a transferred image with high density and excellent uniformity on a recording paper, and also provides a transferred image with excellent abrasion resistance.

[Structure] The present invention includes a dye and/or pigment on a support and a softening point of 70 to 70.
In a thermal transfer recording medium provided with a transfer layer containing a colorant and a binder whose main component is a thermoplastic resin at 140° C., the ratio of the colorant and the paint goo is such that the binder is used in a ratio of 0.00 parts by weight to 1 part by weight of the colorant. 02 to 0.2 parts by weight, and the colorant is present in the form of particles in the transfer layer.

In the thermal transfer recording medium of the present invention, the transfer layer is overlapped with recording paper, and a desired image is formed on the recording paper by thermal printing from the back side of the thermal transfer recording medium. Various conventionally known materials can be used as appropriate. For example, polyester film, polyamide film, polyvinyl chloride film, polyethylene film, polypropylene film, polyimide film,
Examples include plastic films such as polysal 7 film and polycarbonate film, and capacitor paper.

The coloring agent used in the transfer layer of the present invention is obtained by heating and kneading a conventionally known dye and/or pigment and a thermoplastic resin with a softening point of 70 to 140''C, and then pulverizing it into fine particles.The dye and pigment include: Inorganic and organic dyes and pigments used in printing inks, paints, etc. can be used.

Specific examples include carbon black, Disazo Yellow, Brilliant Cardin 6B, Lake Red C1 Phthalocyanine Blue, Kayaset Black KR (Nippon Herbal Medicine), Oil Yellow 3G (Orient Chemical), Kayaset Red -BE (Japanese Herbal Medicine), and Kayaset Blue. -KFL (
Japanese herbal medicines), etc.

As the thermoplastic resin, various resins having a softening point of 70 to 140"C can be used. For example, acrylic resin, methacrylic resin, styrene resin, vinyl acetate resin, vinyl chloride resin, vinylidene chloride resin, petroleum resin, novolac resin, olefin. Examples include resins, polyester resins, polyacetal resins, and copolymers thereof.

If the softening point is lower than 70℃, the high temperature environment of the transferred image (50℃~
If the temperature is higher than 140°C, high energy is required during thermal transfer recording, resulting in problems such as slow recording speed and shortened thermal head life.

The colorant used in the present invention is used in the form of fine particles, and the average particle size in the transfer layer is preferably about 0.1 to 5 μm.The smaller the particle size, the better the thermal sensitivity and resolution, but if it is too small, the abrasion resistance will be poor. If it is too large, thermal sensitivity and resolution will deteriorate.

The ratio of the dye and/or pigment to the thermoplastic resin having a softening point of 70 to 140 DEG C. is about 5 to 100 parts by weight of the thermoplastic resin per 1 part by weight of the dye and/or pigment.

Other binders are used in the transfer layer in an amount of 0.02 to 0.2 parts by weight per 1 part by weight of the colorant. If the amount of binder used is too small, the colorant will be difficult to retain on the support, and will fall off during recording, causing background stains.If the amount of binder used is too large, the colorant will harden on the support. This causes a problem in that the boundary between the transferred area and the non-transferred area becomes less sharp, making it difficult to transfer and record. Therefore, the amount of binder used is most preferably the minimum amount that allows the colorant to be retained on the support.

Conventional binders are used, such as polyvinyl alcohol, methoxycellulose, hydroxyethylcellulose-oxymethylcellulose, polyvinylpyrrolidone, polyacrylamide, starch, gelatin, polyacrylic acid,
These include ethylene/vinyl acetate copolymer, the above-mentioned thermoplastic resin, and the like.

As the recording paper used in the present invention, plain paper, synthetic paper, plastic film, etc. can be used as appropriate.

The thermal transfer recording medium of the present invention can be prepared by mixing the above-described transfer layer forming components with water or a solvent that does not dissolve the colorant, using a stirrer,
The colorant is dispersed using a dispersion means such as a ball mill or an attritor so that the average particle size is 0.1 to 5 μm, and then the colorant is dispersed onto a support with a total solid content of 1 to 10 (]/
It can be obtained by applying the resin to a thickness of m 2 and drying at a temperature below the softening point of the thermoplastic resin in the colorant so as not to fuse the colorant.

Next, the present invention will be roughly explained in detail with reference to Examples and Comparative Examples.

In addition, both "1 part" and "%" shown below are M.
It is based on quantity.

It was pulverized with a jet mill to produce a fine particle coloring agent with an average particle size of 3 μm.

Examples 1 to 4 The above compositions were uniformly mixed using a stirrer to prepare coating liquids. The coating liquid was applied onto a 6 μm thick polyester film using a wire bar so that the amount of adhesion after drying was 4 g/m2, and dried with warm air (50° C.) to obtain the thermal transfer recording medium of the present invention. Ta.

A fine particle coloring agent having an average particle size of 3 μm was prepared using the same composition as in the example. Comparative Comparative Example 3.4 Using the colorant, the following composition was prepared in the same manner as in the example. In Example 1, 1 part of polyvinyl alcohol (10% aqueous solution), 39 parts of water, and polyvinyl alcohol (
10% aqueous solution) 30 parts and 10 parts of water as in Example 1.
Thermal transfer recording media of Comparative Examples 3 and 4 were prepared in the same manner as described above.

A hot-melt ink composition is prepared by uniformly kneading the following composition using a roll mill at a temperature of 100°C, and is applied using a hot-melt coating method. 4 (1 part m, 2 coated on a 6μ thick polyester film,
A thermal transfer recording medium of Comparative Example 5.6 was prepared.

The transfer layer of the thermal transfer recording medium prepared as described above was brought into close contact with the surface of high-quality paper, and printing was performed using a thermal transfer printer by applying an energy of 0.7 mJ/dat.

In order to examine the abrasion resistance of the printed image, the abrasion resistance against cardboard was tested using a lab tester (manufactured by Toyo Seiki) (air temperature 20°C, 50°C). The results were as follows.

Note: Image density: Non-TMA (Macbeth reflection densitometer) uniformity of the solid print area: Good presence of voids (areas where ink has not been transferred) in the solid print area...No voids, rather poor...Slight voids Good/Bad...Many voids. II abrasion resistance: *Number of rubs: 1ω reciprocating load i1 10011/C12 Good...Ink in the printed area is removed and does not stick to the non-printed area.Slightly poor...Ink in the printed area A small amount of ink is removed and a small amount of ink sticks to the non-printed area. A lot of ink is removed from the printed area and a lot of ink sticks to the non-printed area. [Effect] As explained above, according to the thermal transfer recording medium of the present invention, the ink can be printed at high density. A transferred image with good uniformity and excellent abrasion resistance can be obtained.

Claims (1)

[Claims] dye and/or pigment on support and softening point 70-140℃
In a thermal transfer recording medium provided with a transfer layer containing a colorant and a binder whose main component is a thermoplastic resin, the ratio of the colorant and binder used is 0.02 to 1 part by weight of the binder to 1 part by weight of the colorant. A thermal transfer recording medium characterized in that the colorant is 0.2 parts by weight and is present in particulate form in the transfer layer.