JPH0249918B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ink ribbon used in a thermal printer or the like, and particularly to an ink ribbon that performs multiple transfers.

Currently, it is desired that such ink ribbons have a long service life without deteriorating their printing characteristics.

[Conventional technology]

An example of a conventional multiple transfer ink ribbon is shown in FIG. In the figure, 1' is a thermal head,
2' is the base material, 3' is the intermediate adhesive layer, 4' is the ink layer,
5' is a filler.

In the conventional multi-transfer ink ribbon, as shown in the figure, an ink layer 4' is formed by coating and drying ink containing filler 5', all of which have the same particle size, on a base material 2' on which an intermediate adhesive layer 3' has been coated and dried. was forming.

The multi-transfer ink ribbon process is such that when the ink in the part of the ink layer in contact with the paper is consumed, the ink stored between the fillers behind seeps out and replenishes the ink, making the next printing possible. be.
Therefore, in order to extend the life of the ink ribbon, conventional methods have been to reduce the number of fillers contained in the ink layer as shown in Figure 2, or increase the size of one filler (not shown) to reduce the gap between the fillers. It was made wider to increase the amount of ink it could store.

[Problem that the invention seeks to solve]

As mentioned above, if the number of fillers is reduced in order to increase the amount of ink stored in the ink layer, the fillers will separate from each other, making the ink layer unstable, reducing the peel strength of the ink layer, and causing the ink layer including the fillers to Peeling transfer occurs where the toner is peeled off and transferred to the paper, which deteriorates printing characteristics and makes it impossible to perform multiple transfers.

In addition, in the case of an ink layer formed with large filler particles, the gaps between the fillers become wider and the amount of ink that can be stored in the ink layer can be increased, resulting in a longer life. This results in large unevenness and a significant deterioration in printing characteristics.

The object of the present invention is to solve these problems and obtain a multi-transfer ink ribbon with a long life and high print quality.

[Means for solving problems]

In order to solve the above problems, the present invention provides a thermal transfer ink ribbon in which an ink layer containing a filler is adhered and formed on a base material, and the ink layer contains a filler with a large particle size on the base material side. To provide a thermal transfer ink ribbon characterized in that the ink layer has a multilayer structure having an ink layer containing a filler smaller in diameter than the filler in the ink layer on the base material side on the contact surface side with printing paper.

[Effect]

By configuring two or more ink layers containing fillers with different particle sizes as in the present invention, the contact surface with printing paper can be made flat, and the amount of ink stored in the ink layer can also be increased.

〔Example〕

The thermal transfer ink ribbon of the present invention will be explained below with reference to the drawings.

FIG. 1 is a diagram for explaining the thermal transfer ink ribbon of the present invention, in which 1 is a thermal head, 2 is a polyester base material, 3 is an intermediate adhesive layer, 4 is an ink layer containing large filler particles, and 5 is a small particle filler-containing ink layer. 6 is a printing paper, and 7 is a platen.

As the filler, conventionally used inorganic and organic powders such as alumina, diatomaceous earth, Zn powder, Cu powder, Fe powder, and carbon may be used.

First, a 15μmφ filler, dye, paraffin wax, low melting point material (fatty acid ester), and acetone are mixed in a ball mill (a method of mixing the materials and an alumina ball or plastic coating ball in a capped bottle, etc. by rotating it. ) to create ink containing large droplets of filler, and then add 3 μmφ filler, dye, paraffin wax, low melting point material (fatty acid ester),
Acetone is mixed in a ball mill to create a small filler-containing ink.

Then, an intermediate adhesive layer 3 prepared by mixing arbitrary amounts of polyester resin, polyamide resin, carbon black resin, and a solvent using a ball mill is coated on the polyester base material 2 and dried. The thickness at this time is 10μm
(intermediate adhesive layer 3 μm, base material 7 μm).

Thereafter, the ink containing the large filler particles is applied onto the intermediate adhesive layer 3 and dried to form an ink layer 4 containing the large filler particles with a thickness of 7 μm. The ink containing the small filler particles is further coated on the ink layer 4 and dried to form an ink layer 5 containing the small filler particles with a thickness of 3 μm.

At this time, heating is performed for drying and sensitivity improvement, and this heating causes the interface between the ink layer 4 containing large filler particles and the ink layer 5 containing small filler particles to fuse, and the ink from the ink layer 4 to the ink layer 5 during printing is heated. This allows for a smooth flow of water.

Then, the printing paper 6 is sent through the platen 7 to a position where it comes into contact with the surface of the ink layer containing small filler particles, and the ink is transferred to the printing paper 6 by the heat of the head 1 to perform printing.

Using such an ink ribbon, printing was performed by a serial head under the following conditions: energy received by the ink ribbon from the heating dot of the thermal head was 40 mJ/mm ² , the pulse width of the printing pulse to the heating dot was 1.4 mS, and the ambient temperature was 20 ± 1°C. When printed, the following results were obtained.

Table 1 Number of solid black prints 1 2 3 4 Optical reflection density (OD) 1.0 0.9 0.9 0.8 Number of solid black prints 5 Optical reflection density (OD) 0.8 The following table shows the results when using a conventional ink ribbon under the same conditions. This is the result.

Table 2 Number of solid black prints 1 2 3 4 Optical reflection density (OD) 0.9 0.8 0.7 0.6 Number of solid black prints 5 Optical reflection density (OD) 0.5 In this example, the ink layer had a two-layer structure, but from the base material side If the structure is such that the particle size of the filler contained decreases toward the contact surface of the printing paper, there will be no problem with three or more layers.

〔effect〕

By forming multiple ink layers each containing fillers with different particle sizes as in the present invention, when the thickness of the ink layer, the number of fillers, etc. are set to the same conditions, it is possible to Compared to the case where the ink layer contains ink, the contact surface of the paper can be made flat, and the amount of ink stored in the ink layer can also be increased. As a result, as is clear from Tables 1 and 2 above, an ink ribbon with excellent printing characteristics and long life can be obtained.

Furthermore, the ink layer itself is less likely to peel off and transfer to paper.

[Brief explanation of the drawing]

FIG. 1 shows a thermal transfer ink ribbon according to the present invention, and FIG. 2 shows a conventional thermal transfer ink ribbon. In the figure, 1 is a thermal head, 2 is a polyester base material, 3 is an intermediate adhesive layer, 4 is an ink layer containing large filler particles, 5 is an ink layer containing small filler particles, 6 is printing paper, and 7 is a platen. .

Claims (1)

[Scope of Claims] 1. A thermal transfer ink ribbon in which an ink layer containing a filler is adhered and formed on a base material, wherein the ink layer contains an ink layer containing a filler with a large particle size on the base material side, A thermal transfer ink ribbon characterized by having a multilayer structure including an ink layer containing a filler smaller in diameter than the filler in the ink layer on the base material side on the side of the contact surface with printing paper.