JPH0221396B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of an ink sheet for thermal copying.

FIG. 1 shows the structure of a copying paper using a conventional thermal copying ink sheet. In the figure, 1
is a thermal copying ink sheet, which has a thermal recording layer 1 coated on a thin base paper 12 of about 40 to 70 μm.
1 and a thermofusible solid ink layer 13 coated on the other side of the base paper 12. On the side of the solid ink layer 13 of the thermal copying ink sheet 1, plain paper 2, which is a transfer medium, is placed.

Recording on a conventional thermal copying ink sheet is carried out as follows. Heat generating part 1 of thermal recording head 100
001 is heated while being pressed against the heat-sensitive recording layer 11 side, a part 11a of the heat-sensitive recording layer 11 develops color, and then a part 13a of the solid ink layer 13 on the back side is heated and melted through the base paper 12 to form a normal ink layer. Weld onto paper 2. Next, by moving the plain paper 2 and the thermal copying ink sheet 1 in the direction of the arrow and peeling the thermal copying ink sheet 1 from the plain paper 2, a solid ink image 13a,
13b on the thermosensitive recording layer 11, the thermosensitive coloring image 11a,
11b can be obtained respectively.

In conventional thermal copying ink sheets, the thermal recording layer 11 is formed by applying an emulsion of a thermal composition onto the base paper 12 using aqueous coating. It was necessary to make it thicker than at least 40 μm. This has resulted in two drawbacks: a decrease in heat transfer efficiency to the solid ink layer 13 on the back surface of the base paper 12 and a decrease in resolution due to heat diffusion.

This invention was made in order to eliminate the drawbacks of the above-mentioned conventional thermal recording layer.This invention allows the use of a base paper thinner than 40μm, reduces resolution deterioration, has good thermal efficiency, and improves the printing quality of the thermal recording layer. The present invention provides an ink sheet for copying.

FIG. 2 shows an embodiment of the invention. In the figure, the same reference numerals as in FIG. 1 indicate the same or corresponding parts, respectively. 14 is a base film such as thin capacitor paper or glassine paper with a thickness of about 8 to 35 μm;
On one side of the base film 14 is a vapor-deposited metal layer 15 of aluminum or the like, and on the other side is a waterproof layer 1 consisting of a layer of wax, lacquer, resin, or vapor-deposited resin such as polyparaxylylene with a thickness of about 0.1 μm to 20 μm.
6 are formed respectively. Together, these constitute what corresponds to the conventional base paper 12. A heat-sensitive recording layer is coated on the waterproof layer 16 by a water-based coating method, and a solid ink layer 13 is coated on the metal vapor deposited layer 15 on the other side by a hot-melt coating method, and these are integrated. A thermal copying ink sheet 10 is constituted. or,
A plain paper 2 is placed in contact with the solid ink layer 13.

The recording method of the thermal copying ink sheet of this invention is the same as that of the conventional example shown in FIG. 1, so the explanation will be omitted. In the thermal copying ink sheet according to the present invention, a metal vapor deposition layer 15 and a waterproof layer 16 are provided.
has the following characteristic functions.

That is, the upper waterproof layer 16 is the heat-sensitive recording layer 11.
Acts as a water-resistant layer when applied onto the base film 14, and 8~
Thin base paper of about 35μm, such as capacitor paper,
This makes it possible to use glassine paper etc. as a base film. This makes the base paper itself retain its aqueous coating properties, compared to thermal copying ink sheets that use conventional thick base paper.
Print resolution and thermal efficiency can be significantly improved.
For example, when comparing the conventional thermal copying ink sheet with a base paper of 40 μm and the thermal copying ink sheet of this invention with a base paper of 10 μm, the resolution is about 3 lines/mm and 10 lines/mm, and the thermal efficiency is about 40%.
We found that each could be improved.

Further, in conventional thermal copying ink sheets, when a thin base paper is used, the solid ink layer 13 becomes more transparent on the thermal recording layer 11 side, resulting in a blackish image and a significant decrease in contrast. In this invention, since the metal vapor deposition layer 15 acts as an opaque layer, the solid ink layer 13
Since the image does not show through, a good image without so-called background fog can be obtained.

Here, it is most advantageous to use aluminum for the metal vapor deposition layer 15 in terms of cost, but it is not limited to a specific metal vapor deposition layer or metal compound layer as long as the transmittance is at least less than 50%.

Further, as the waterproof layer 16, waxes such as ester or carnauba wax, paints such as varnishes, or paints such as lacquer are suitable. The coating layer is not limited to a specific material or a specific mixture or combination of materials as long as the coating layer can add properties that can improve the water resistance of the film 14.

Furthermore, in order to increase the water resistance of the waterproof layer 16, hydrophobic waxes, varnishes, and lacquers are suitable, but in order to uniformly and firmly apply the heat-sensitive recording layer 11, it is necessary to add hydrophilic properties. . For this reason,
In this invention, a surfactant such as metal soap is added to the waterproof layer for the purpose of adding hydrophilicity, or inorganic pigment particles are added at a concentration of 15 to 95 weight percent to increase the adhesive strength of the heat-sensitive recording layer by creating fine irregularities on the surface. It was confirmed that adding it was effective.

In addition, in the above embodiments, only capacitor paper or glassine paper was used as the base paper, but this was selected because it was easy to obtain thin paper with a thickness of about 8 to 35 μm, and it was also possible to use a specific type of paper. It is not limited to paper.

FIG. 3 shows another embodiment of the thermal copying sheet 10 of the present invention. A is metal vapor deposition layer 1
5 and a waterproof layer 16 are laminated on the same side of the base film 14, and the thermosensitive recording layer 11 is formed by coating on the waterproof layer 16. In embodiment B, the stacking order of the metal vapor deposited layer 15 and the waterproof layer 16 is reversed. In C, waterproof layers 16 are provided on both sides of the base film 14, and the water resistance of the base film 14 can be further improved. D is one in which the base film 14 is impregnated with a waterproofing agent for the waterproof layer 16, and the structure is simplified using the waterproofed base layer 17.

As described above, many changes are possible when implementing this invention, but in any case, 1. the base film is waterproofed, 2. an opaque layer made of a metal vapor deposited layer on the base film. It is necessary to satisfy the following two points:

As detailed above, according to the thermal copying ink sheet of the present invention, since the base film is provided with a waterproof layer, a thin base paper can be used, and the recorded image quality can be significantly improved by inserting the metal vapor deposited layer. There is an effect that can be achieved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the structure of a conventional thermal copying ink sheet, FIG. 2 is a diagram showing an embodiment of the thermal copying ink sheet of the present invention, and FIG. 3 is a diagram showing another example of the thermal copying ink sheet of the present invention. It is a figure showing an example of. In the figure, 11 is a heat-sensitive recording layer, 13 is a solid ink layer, 14 is a base film, 15 is a metal vapor deposition layer, and 16 is a waterproof layer. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1 A base film, a metal vapor deposited layer provided on one side of the base film, and a waterproof layer provided on one or both sides of the base film, and at least the waterproof layer is provided. 1. An ink sheet for thermal copying, comprising a heat-sensitive layer formed by an aqueous coating method on one side and a heat-melting solid ink layer on the other side. 2. The thermal copying according to claim 1, wherein the waterproof layer has sufficient waterproofness for aqueous coating of the thermal recording layer and sufficient adhesiveness for adhering the thermal recording layer. ink sheet. 3. The ink sheet for thermal copying according to claim 1 or 2, characterized in that the base film is made waterproof by impregnating a waterproof layer into the base film.