JPS62196185A - Thermal transfer material - Google Patents

Abstract

PURPOSE:To provide a thermal transfer material giving high resolution and capable of copying with high-speed printing, by using a fatty acid ester and paraffin wax as a binder, in a specified weight ration of 1:1-1:5. CONSTITUTION:A fatty acid ester and paraffin wax are used in a weight ratio of 1:1-1:5. If the amount of the ester is less than the weight ratio range, the capability of dispersing a coloring agent is lowered, so that reflection density is lowered, resulting in obscure prints. In addition, penetration is raised, so that ground contamination is more liable to occur on high-speed printing, and since an ink becomes softer, transfer area ratio exceeds 100%, and resolution is lowered. On the other hand, if the amount of the ester is in excess of the weight ratio range, the properties of the ester are displayed predominantly over the properties of the wax, so that the ink becomes harder, the coefficients of expansion and contraction of the ink become higher, and the transfer area ratio becomes too low to obtain clear prints.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a heat-sensitive transfer member, and more particularly to an improvement in the binder of a heat-meltable ink thereof.

[Conventional technology]

A heat-sensitive transfer member is basically composed of a support such as a polyester film and a heat-meltable ink provided in a layer on the support.

The above-mentioned heat-melting ink is, for example, JP-A No. 55-3
As shown in Japanese Patent Application No. 919, it is composed of coloring agents such as pigments and dyes, a hot-melt binder made of wax, petroleum resin, and a softener.

[Problem that the invention seeks to solve]

However, in the heat-melting inks that have been proposed so far, the selection of constituent materials and their composition ratios have not been deeply studied, and as a result, the melting point, heat of fusion, penetration, expansion/contraction rate, viscosity, etc. There was a problem that the physical properties of the ink were unbalanced, and either the reflection density or the transfer area ratio was deviated from the appropriate value, and the ink could not adequately support high-resolution and high-speed printing.

[Means for solving problems]

The present invention solves the above problems by using fatty acid ester and paraffin wax as a binder and limiting the composition ratio to a specific range, thereby making it possible to cope with high-resolution and high-speed printing.

In the present invention, examples of the fatty acid ester used as a binder component of the hot-melt ink include natural waxes such as carnauba wax, ochuri wax, and cardelia wax, myricyl palmitate, myricyl stearate, cetyl palmitate, and stearic acid. Examples include cetyl. These fatty acid esters are
It has a low penetration rate and belongs to the so-called hard wax category, and has the advantage of facilitating the dispersion of colorants. However, it expands and contracts in response to heat, and when ink is applied in a thin film, the product tends to curl. It has the disadvantage that it is difficult to form a film.

On the other hand, paraffin wax has a high penetration rate and belongs to the so-called soft wax, and has a moderate thermal response (
Melting point, heat of fusion), and expansion/contraction is smaller than fatty acid esters, so when applying ink, it has the advantage that the product does not curl or cracks occur in the film, but it hardly disperses the colorant. Therefore, it has the disadvantage that ink that allows clear printing cannot be obtained.

Therefore, in the present invention, by mixing fatty acid ester and paraffin wax, we take advantage of the advantages of both.
In order to compensate for the shortcomings, various studies were carried out and the objective was achieved by specifying the composition ratio of fatty acid ester and paraffin wax to a weight ratio of 1:1 to 1:5.

In the present invention, the composition ratio of fatty acid ester and paraffin wax is set to 1:1 to 1:5 by weight, as is clear from the above description of their characteristics and the description of the examples below. If the composition ratio of the fatty acid ester is less than the above range, the ability to disperse the colorant will decrease,
As a result, the reflection density becomes low, making the print unclear, and the penetration becomes high, so when printing at high speed, background smudges tend to occur, and the ink becomes soft, so the transfer area ratio exceeds 100%. This is because the resolution decreases.

On the other hand, if the composition ratio of the fatty acid ester exceeds the above range, the characteristics of the fatty acid ester will be strong, the characteristics of the paraffin wax will be canceled out, the ink will become hard (and the expansion and contraction rate will increase, and the transfer area ratio will decrease). This is because if it becomes too much, the print becomes unclear.

The cleavage of the heat-melting ink is carried out by adjusting the composition ratio of fatty acid ester and paraffin wax to the above range, and adding colorant 6 to this.
, a softener, a film-forming agent, etc., and further optionally additives such as an antioxidant, an antistatic agent, a lubricant, etc., and are melted and mixed.

The amounts of these components in the hot-melt ink are not particularly limited, but include 40 to 80 parts by weight of the binder (fatty acid ester and paraffin wax) and 10 parts by weight of the colorant, based on 100 parts by weight of the total N of the hot-melt ink. ~30 parts by weight,
When 5 to 30 parts by weight of a film forming agent, 3 to 20 parts by weight of a softener, and other additives are required, it is preferable to use 10 to 30 parts by weight of the additives.

As the colorant, various pigments or dyes conventionally used in the field of copying paper, such as carbon black, aniline blank, and nigrosine, can be used without any particular restrictions.

Examples of film-forming agents include petroleum resins, polyvinyl acetate, polystyrene, styrene-butadiene copolymers, cellulose esters, cellulose ethers, acrylic resins, etc., which have film-forming properties and are easily heat-meltable. Substances that can be used are preferably used.

Further, as the softening agent, for example, liquid paraffin, process oil, polyethylene glycol, vaseline, various vegetable oils, etc. are preferably used.

As the support, for example, polyester film (polyethylene terephthalate film), polyimide film, polycarbonate film, nylon film, etc. are used.

〔Example〕

Using a polyester film with a thickness of 3.5 μm as a support, hot-melt ink having the composition shown in Table 1 was applied to the surface of this film using a hot-melt coating method so that the coating thickness was 3 μm, and after cooling, It was cut into a predetermined width to produce a ribbon-shaped thermal transfer body with a width of 13 mm.

The paraffin wax used in the preparation of the hot melt ink shown in Table 1 above was HNP manufactured by Nippon Seiro Co., Ltd.
-10 (product symbol), and the fatty acid ester has 4 carbon atoms.
80-85i of fatty acid ester of 8-64! ! (Contains 3% natural carnauba wax.

In addition, the petroleum resin was Escoretz 1102 (trade name) manufactured by EXXON, the softener was liquid paraffin, and the colorant was carbon blank. The ink was prepared by heating and melting each of the materials of sample numbers (1) to (Vl), and then kneading them in a homomixer for 8 hours to ensure that the carbon black was sufficiently dispersed in the ink.

Using the thermal transfer body produced as described above, the performance of the ink was evaluated by printing on plain paper using a high-density thermal printer (a printer with a thermal head of 8 dots/1111). The results are shown in Table 2.

In general, when the reflection density, which indicates ink performance, is 1.5 or more, the print is clear, and when it exceeds 1.9, the contrast with the background color of the transfer paper is too strong, making it easy for the eyes to get tired. In addition, when the transfer area ratio is 100%, the printed dots faithfully reproduce the dots of the thermal head, and the resolution is considered to be excellent, and when the transfer area ratio goes below 100%, the printing becomes worse. If the transfer area ratio greatly exceeds 100%, the lines constituting the characters will overlap and the resolution will decrease.

The smaller the expansion/contraction rate, the easier it is to produce a thermal transfer material, and the smaller the difference in the size of the characters when the ink is thermally melted and the size of the characters after printing.
Approximately 6 is appropriate; if the penetration is smaller than the above range, the ink will become hard and the transfer area ratio will be small; if the penetration is larger than the above range, the ink will become soft, and when printing at high speed, background stains may occur. This tends to occur, and the transfer area ratio exceeds 100%.

The evaluation criteria for ink performance are as described above, but as shown in Table 2, the composition ratio of fatty acid ester and paraffin wax is within the range of 1:1 to 1:5 by weight, Sample numbers (I), (IV) and (
The thermal transfer material V) has a high reflection density, a transfer area ratio of around 100%, an expansion/contraction rate not so large, and an appropriate penetration degree, and sample numbers (I) and (2) outside the present invention.
The overall print evaluation was excellent compared to the thermal transfer materials n) and (■).

〔Effect of the invention〕

As explained above, in the present invention, fatty acid ester and paraffin wax are used as the binder, and by specifying the composition ratio in the range of IX 1 to 1:5 by weight, the present invention provides a high-resolution print that can support high-speed printing. We were able to provide a thermal transfer material.

Claims (1)

[Claims] (1) In a heat-sensitive transfer material having a heat-melting ink layer on a support, the heat-melting ink layer contains a fatty acid ester and a paraffin wax as a binder, and the composition ratio of the fatty acid ester and the paraffin wax is by weight. A thermal transfer material characterized in that the ratio is 1:1 to 1:5.