JPS6270087A - Thermal transfer ink - Google Patents

Abstract

PURPOSE:To increase the cohesive force of an ink in a molten state, enhance adhesion of the ink to a paper and enable clear images to be printed, by incorporating a coloring agent and a thermoplastic organic substance comprising at least a polyamide resin having a softening point in a specified range. CONSTITUTION:A coloring agent and a thermoplastic organic substance comprising at least a polyamide resin are incorporated in an ink. The polyamide resin may be produced by any method, as far as the resin has a softening point of 50-100 deg.C. If the softening point is higher than 100 deg.C, the melting temperature of the ink is so high that it is difficult to obtain a temperature at which transfer can be effected, by ordinary thermal transfer energy. A polyamide resin having a softening point of lower than 50 deg.C has an effect on blocking during preservation of ink sheets, and therefore it can not be used. The polyamide resin is preferably used in an amount of 50-20wt%. With this arrangement, the melting temperature of the ink is not high, and the adhesion of the ink to a transfer recording paper is strong, so that clear printing can be performed even on a paper having low smoothness.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ink composition used for a thermal transfer recording sheet used in a thermal transfer printer.

[Conventional technology]

In recent years, thermal transfer recording has been used in many fields such as facsimiles, computer terminals, recorders, and printers due to its advantages of being non-impact, noiseless, maintenance-free, low cost, compact and lightweight, and capable of color printing. It's here.

The ink for thermal transfer recording sheets used in thermal transfer printers is heat-melting, and in order to achieve a sharp phase change from solid to liquid to solid during thermal transfer, the main component of the ink composition has traditionally been entirely hydrocarbon. It is made by dispersing natural wax and/or synthetic wax on colorants such as pigments and dyes, and some amount of synthetic resin or plasticizer is added to this to strengthen the film and improve adhesion. .

[Problem that the invention seeks to solve]

As mentioned above, since the main component of conventional thermal transfer inks is wax, they have a weak cohesive force when melted, resulting in unclear images when printed on rough paper (low smooth paper).

Rough Hl has large diameter and deep pores on the paper surface, and the contact area with the ink during transfer is small, so the cohesive force is small.
If the ink has weak adhesion to paper, the portion that is not in contact will remain on the base material of the thermal transfer ink sheet and will not be transferred to the paper. In addition, simply increasing the proportion of synthetic resins that are compatible with wax to increase cohesive force will increase the adhesion of the ink sheet to the base material, resulting in poor peeling from the base material and an increase in the softening point. Therefore, it cannot be transferred using a conventional thermal head.

This invention attempts to solve this problem, and its purpose is to increase the cohesive force in the molten state without increasing the melting temperature of the wax, which is the main component, and to improve the adhesion to paper.
To provide a thermal transfer ink capable of obtaining a clear printed image even when transferred to rough paper (low smooth paper).

[Means for solving problems]

The above problem? The structure to solve this problem is a thermal transfer ink containing at least a polyamide resin as a colorant and a thermoplastic organic substance. Specifically, a polyamide resin having a softening point of 50°C to 100°C is used, and a colorant and a polyamide resin are used as the thermoplastic organic substance. As such, pigments and/or oil-soluble dyes are used.

[For production]

Polyamide resin has polar groups such as amine groups, carbonyl groups, and amide groups in its molecules, and is suitable for metals, paper, wood, ceramics,
Shows good adhesion to a wide range of materials such as plastics,
This invention is an application of this property.

The main properties required of thermal transfer inks include strong adhesion to paper, which is the transfer medium, and weak adhesion to the base material of the ink sheet. takes advantage of the property that the polyamide resin used has poor compatibility with other thermoplastic organic substances (especially wax), and during transfer, the ink melts and is transferred to the medium. The cellulose of certain papers and polyamide resin adhere strongly, and after being transferred, it solidifies upon cooling, and due to the properties of the wax, it becomes easy to peel off from the base material of the ink sheet. These effects enable clear printing even on rough paper (low-smooth paper).

The polyamide resin used in this invention has a softening point of 50°C.
Any manufacturing method may be used as long as the temperature is 100°C. If the temperature is 100° C. or higher, the melting temperature is high, and it is difficult to raise the temperature to a level at which transfer can be performed using normal thermal transfer energy, and therefore, it cannot be used. If the temperature is below 50℃, it will affect the blocking during storage of the ink sheet.
Cannot be used.

The amount of polyamide resin used in this invention is 50
~20% by weight is adequate.

Other thermoplastic organic substances include wax and/or thermoplastic resin, and the softening point is 50°C to 50°C.
0°C is suitable.

As the wax, both natural wax and synthetic wax can be used.

Examples of natural waxes include carnauba wax, paraffin wax, and microcrystalline wax.

Synthetic waxes include polyethylene wax and the like. These waxes can be used alone or in combination,
The appropriate amount to use is 50 to 90 kg/kts.

The thermoplastic resin may be any resin as long as it is well compatible with the above-mentioned wax, and specific examples thereof include ethylene vinyl acetate copolymer, polyurethane ethyl acrylate copolymer, polyethylene, and polyester, which may be used alone or in combination. The appropriate amount is 3 to 10% by weight.

The coloring materials used in this invention are pigments and oil-soluble dyes, and these can be used alone or in combination.

The amount used is 2-20% by weight.

Hereinafter, this invention will be specifically explained with reference to Examples.

〔Example〕

All amounts (%) of ink components shown in the following examples are by weight.

Example 1 Composition of ink Paraffin wax 150°y 72 inches [Nippon Seiro (manufactured by M)] Carnauba wax No. 1 10% Polyamide resin 10% [Macromelt 607
1. Henkel Hakusui (manufactured) Kagen Black
8% (MA-100 manufactured by Mitsubishi Chemical Industries, Ltd.) A mixture of the above composition was predispersed with a planetary mixer at 120°C for 60 minutes), cooled and solidified, pulverized, and then dispersed in a three-roll mill (afterwards). One black thermal transfer ink was prepared (roll and middle roll were passed through 15 times at 100°C and the front roll was cooled with water).

Comparative Example 1 A mixture of the same components as in Example 1 was used in the same manner except that an ethylene vinyl acetate copolymer (Evaflex 31〇 Mikata Polychemical (manufactured by Kai)) was used instead of the polyamide resin in Example 1 above. , to make thermal transfer ink through dispersion treatment.

Example 2 Composition of ink Paraffin wax 130°F 60% [manufactured by Nippon Seikon (…) Oxidized wax 16th grade (1i
s p 6o 1a, Nippon Seikon (manufactured by 轡) ethylene vinyl acetate copolymer 3% [Ebachi] D20
21. Polyamide resin manufactured by Sumitomo Chemical
15% (DPXTO55, Henkel Hakusui (candle lining) C, L Pigment Red 22 6
% [Brilliant Fast Scarlet] A mixture of the above composition was dispersed in the same manner as in Example 1 to form a red thermal transfer ink. I made it.

Comparative Example 2 A mixture of the same components as in Example 2 was dispersed by the same method except that ethylene ethyl acrylate copolymer (A, 702, manufactured by Mikata Polychemical ■) was used instead of the polyamide resin in Example 2. Then, we created a thermal transfer ink.

Example 5 Composition of ink Paraffin wax 120°F 50% [Nippon Spirit (made in barrel)] Polyethylene wax 22% [Sunwax 16SP, Mitsubishi Chemical Industries (El, dJ Carnauba Wax No. 1 12%) Polyamide Jugetsuji 8% (GRILTE)
X5G, Dainippon Ink & Chemicals (3) 231! ” Carbon black 6% (MA-100
, Mitsubishi Chemical Industries (Sushi C, 1, Nrubento Black 6 2% [Oil Blank HBB, manufactured by Rient Kagaku Kogyo Co., Ltd.]) A mixture of the above composition was dispersed in the same manner as in Example 1 to make a black thermal transfer. I made ink money.

Comparative Example 3 Ethylene ethyl acrylate) (NUC6070, Nippon Unicar (ELM)) was used instead of the polyamide resin of Example 6.
A thermal transfer ink was prepared by dispersing a mixture of the same components as in Example 3 in the same manner as in Example 3, except that T- was used.

Each ink obtained from Examples 1, 2.3 and Comparative Examples + and 2.3 was heated and melted to a thickness of 4
The ink was coated onto a μm PET film using a wire coating to create a 445 μm ink for thermal transfer.

This thermal transfer ink sheet is all around, bond paper with Beck smoothness of 4 seconds and 15 seconds, PPC copy paper with 40 seconds,
At a heat application amount of 10 DPI on thermal transfer paper for 180 seconds, it was transferred at [16 J/ (Lot:)].

The results are shown in the table.

table ○: Very good with no omissions.

Δ: There is a slight omission.

×: There are many omissions.

〔Effect of the invention〕

As explained above, the thermal transfer ink of the present invention has a lower melting temperature (transfer temperature) than conventional thermal transfer inks, and has strong adhesion to the transfer paper, so it can be used on rough paper (low smooth paper). Clear printing is possible even on surfaces.

Also, the thermal transfer ink of this invention? If used, thermal transfer using a thermal head, energizing thermal transfer using a current-carrying head, etc.
Since the heat applying means may be based on any principle, it can be used with any type of printer that attempts to obtain a record by transferring heat-fusible ink to a transfer medium.

that's all

Claims (3)

[Claims] (1) A thermal transfer ink characterized by containing at least a polyamide resin as a colorant and a thermoplastic organic substance. (2) The thermal transfer ink according to claim 1, wherein the polyamide resin has a softening point of 50°C to 100°C. (3) The thermal transfer ink according to claim 1, wherein the colorant is a pigment and/or an oil-soluble dye.