JPS59165691A - Thermal transfer ink sheet - Google Patents

Abstract

PURPOSE:To provide the titled sheet hardly generating irregularity in transfer density even when being repeatedly used and favorable in fixability of a transfer recording surface, wherein particulates coated thereon with a vinyl acetate base resin are used as solid particulates for constituting an ink layer. CONSTITUTION:An ink consisting of solid particulates (preferably, carbon black) 3a coated thereon with a vinyl acetate base resin (e.g., ethylene-vinyl acetate copolymer), a dye 3b and a low melting point material (e.g., a fatty acid amide) 3c is applied onto a base 1 to provide an ink layer 3, thereby obtaining the objective sheet. EFFECT:The period of time required for kneading an ink coating liquid can be shortened, and smoothness of the ink layer is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field) The present invention relates to a heat transfer ink sheet that can be used repeatedly, and in particular to a process in which ink is transferred to a medium by heating the ink sheet with a printing element. The present invention relates to a structure of a thermal transfer ink sheet to prevent deterioration of transfer ability due to seepage.

(Prior art and background) The printing method that has traditionally been called thermal printing uses a heating element (thermal head) that can generate heat using electrical signals.
This depended on the combination of a special paper (thermal paper) that develops color when heated. However, this conventional configuration uses two heating elements but repeatedly uses thermal transfer ink sheets (or ribbons) due to the high cost of paper during operation, poor storage stability, and lack of development potential such as colorization. A printing method that uses a possible material to transfer onto plain paper is being considered.

The object of the present invention is an ink sheet used in such a thermal transfer printing method.

In conventional reusable ink sheets used in such printing methods, the most effective means is to add fine powder to the ink layer in order to provide a repeatable function.

This fine powder includes organic and inorganic pigments.

All kinds of powders such as metals and metal oxides can be used.

Repeated transfer was possible. However, all of these repeated transfers were so-called peeling transfers in which the ink layer itself, including the powder, was gradually consumed to varying degrees. For this reason, unevenness corresponding to the pattern area is formed on the surface of the ink layer after transfer, and as the transfer is repeated, contact between the recording paper and the surface of the ink layer becomes uneven, resulting in a decrease in print quality. invite Further, although the ink transferred to the recording paper either permeates the paper or solidifies as it is, the powder cannot help but remain on the paper surface, which worsens the fixing performance.

This is thought to be due to the fact that the structure, which corresponds to a stone wall formed of fine powder, does not have sufficient strength. Among the powders mentioned above, carbon blank has a strong cohesive force and exhibits relatively good repeatability, but even in this case, repeated use often caused partial peeling transfer.

(Purpose and Features) The present invention was conceived in view of the above background, and the purpose is to provide a thermal transfer ink sheet with improved repeated use characteristics. In a reusable ink sheet for thermal transfer recording comprising an ink layer having a dye, a low melting point material, and a solid fine powder formed thereon, the solid fine powder includes:
The ink layer is formed using a powder whose surface is coated with a material containing vinyl resin as a component.

(Embodiment) The figure is an explanatory diagram of one embodiment of the present invention, and is for explaining the structure of an ink sheet. As shown in the figure, the ink sheet is
Strength base material 1 made of a plastic sheet such as polyethylene or terephthalate (thickness 10.t+ in this example)
m) A polyamide resin having a thickness of about 10 pm is applied thereon as the intermediate layer 2, and then an ink layer 3 is formed by the process shown below. As the composition of the ink layer 3.

3a: o, s parts by weight of a carbon blank whose surface is coated with an ethylene-vinyl acetate copolymer 3b: 1 part by weight of a black dye (for example, Nippon Kayaku Kaya's trade name Kayaset Black K-R) 3C: 2 parts by weight of a low-melting binder (for example fatty acid amide) together with 25 parts by weight of acetone as a solvent.

After kneading and dispersing for 24 hours using a ball mill.

It was applied onto the intermediate layer 2 and heated to evaporate the acetone to form an ink layer with a thickness of 22 m.

Then, in order to evaluate the ink sheet produced in this way, using a hand-held thermal facsimile device, each dot of the print head was heated for 0.4 W''T4 ms, and as a result, the applied energy density was 4 Q Ilj
Transfer recording was performed on printing paper under the condition of "/va".

As a control group, a carbon black whose surface was coated with polyethylene-vinyl acetate copolymer in the composition described above was replaced with untreated carbon black, and the performance between the two was compared. We compared the differences.

Using both ink sheets under the above conditions of the thermal facsimile device described above, printing was performed repeatedly using the same location on the ink sheet and the recording paper was repeatedly printed at new locations one after another.1 As a result, high-density printing was obtained in both cases. Even on the 10th printing, the printing was sufficiently legible and clear, but as printing was continued while changing the printing pattern, unevenness in transfer density became noticeable in the control group.

In addition, when the ink layer of the control group was viewed under a microscope, there were dents on the surface, and when the transferred image on the recording paper was rubbed by hand, the transferred image was scratched and smudged, and even one hand was stained.
During repeated printing, even though the transfer density was sufficient up to that point, the ink layer occasionally peeled off in blocks or leaves much larger than a single dot. .

This seems to clearly indicate that the carbon black itself was also transferred and consumed during printing.

On the other hand, the printing example in the embodiment shows that even if you rub it with your hands, it will not get dirty.
There was no scratching or staining of the transferred image, and unevenness in ink density was not noticeable.

(Discussion and supplementary information) Considering these results, solid fine powder can be compared to “
It is a structural material in the ink layer, like a stone wall, and contains dye and low-melting point material between them, and is bonded by them. However, when the dye and low-melting point material melt due to heating, there is nothing to bond with and it falls off. It is thought that if unevenness is formed on the surface due to falling off, there will be a difference in the adhesion to the recording paper and uneven transfer will occur.In the present invention, the solid fine powder itself can also add mutual bonding force. During the process of forming an ink layer using acetone as a solvent using a surface coated with vinyl acetate resin in advance, bonding occurs between the vinyl acetate resins on the surface, making the stone wall look like a stone wall.
It can be said that by changing to a "sponge", the dye and the low melting point material will not fall off even if they melt.

Although carbon black was used as the solid fine powder in the examples, since it is originally a kind of structural material, it may be a material that is not compatible with other ink components, is solid at the thermal transfer temperature, and has mechanical strength. Ba.

Needless to say, it is possible to use both organic and inorganic materials and to coat the surface.

(Effects) As explained above, according to the present invention, since only the ink bleeds out and is transferred, the thermal transfer ink is an excellent thermal transfer ink that is unlikely to cause uneven transfer density even after repeated use and has good fixation properties on the transfer recording surface. A sheet is obtained.

3.The surface-coated powder is kneaded using acetone as a solvent.In the process of manufacturing the ink coating liquid before coating, the dispersibility is better than that of carbon black itself, and the kneading time can be shortened. Another feature is that it can improve sexual performance.

[Brief explanation of drawings]

The figure is an explanatory diagram of one embodiment of the present invention. In the figure, 1 is a base material, 2 is an intermediate layer, 3 is an ink layer 3a, a dye,
3b is a low melting point material, 3c is a surface coated solid fine powder

Claims (1)

[Claims] A reusable ink sheet for thermal transfer recording, which is formed by forming an ink layer containing a dye, a low-melting point material, and a solid fine powder on a base material, the solid fine powder having a vinyl acetate resin on the powder surface. A thermal transfer ink sheet, characterized in that the ink layer is formed using a material whose surface is coated with a material containing as a component.