JPS6160796B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In electrographic printing paper, a surface white coating layer is provided on a semiconductive film base in order to improve readability after plate making. Because of this surface coating layer (hereinafter referred to as the surface layer), it contrasts with the characters, figures, etc. that have been blackened by discharge perforation, and is therefore readable. Therefore, in order to be able to easily distinguish perforated and blackened characters, figures, etc., the surface layer does not necessarily have to be achromatic, but must have an appropriate brightness.

In addition, in order not to impair the plate-making properties of the Tensha base paper, it is desirable that the surface layer has a volume resistivity of 10 ⁶ to 10 ¹⁴ Ωcm, and since this surface layer comes into direct contact with the recording needle during plate-making, it is difficult to record. The surface must be smooth to avoid excessive wear on the needle.

Conventionally, in order to meet these requirements, a white pigment such as titanium oxide has been added to the surface layer to give it whiteness, and carbon black has been added to adjust the electrical resistance. However, since carbon black is originally black, the addition of carbon black reduces its whiteness.
Readability deteriorates. If the amount of white pigment is increased to compensate for this, the amount of pigment will be excessive compared to the amount of binder in the surface layer, which will reduce the coating strength of the surface layer and the adhesion with the film base. There are problems such as the surface layer peeling off due to the scanning of the needle.
Moreover, since the surface smoothness is also reduced, the wear of the recording stylus is accelerated.

In particular, the performance of plate-making machines has improved in recent years, and the speed of plate-making machines has increased, and the strength and smoothness of the surface layer are required to be even greater due to the increase in cylinder rotation speed and recording needle contact pressure. . In addition, since polyvinyl chloride is used for the base film of conventional electric recording paper, there are environmental health problems.
Attempts have been made to use polyethylene that does not contain chlorine, but as is well known, polyethylene is non-polar and has poor adhesion, and when coating a surface layer on it, it requires even greater adhesion than the polyvinyl chloride type. However, conventional surface layers cannot satisfactorily meet these requirements for the reasons mentioned above.

However, as a result of research, the present inventors have found that these requirements can be met by using leafing-shaped scaly aluminum powder or brass powder in the surface layer.

In other words, these leafing-type aluminum powders or brass powders are conductive, and unlike carbon black, their color tone is silvery white or golden white, so even if they are added, they do not impair readability; It is something that improves. Therefore, even if these metal powders are used to adjust the electrical resistance, there is no need to increase the amount of white pigment added.

In particular, if leafing-type aluminum powder or brass powder is used, these metal powders tend to concentrate near the surface and align parallel to the surface, so the light reflection is large compared to the amount added. This improves readability, and since there is less metal powder at the adhesive interface between the film base and the surface layer, the adhesive strength is less likely to deteriorate.

As described above, since the leafing type scaly aluminum powder or brass powder tends to be arranged parallel to the surface, it also gives favorable results in terms of surface smoothness.

In addition, the sheer effect of these scaly aluminum powders or brass powders has the effect of blocking light, moisture, etc. and preventing deterioration of the surface layer. It also contributes to improving value.

By using leafing-type aluminum powder or brass powder in this way, not only is it adaptable to high-speed plate-making machines, but performance is also improved for use in low- and medium-speed plate-making machines.

These leafing-type aluminum powders or brass powders can be used alone to adjust electrical resistance and provide readability, or they may be used in combination with carbon black, titanium oxide, etc.

In addition, colored metal powder may be used to give a favorable effect particularly on the appearance of the product.

Example: Modified rubber 10 parts Plasticizer manufactured by Itoto Metal Foil Co., Ltd. 3 parts Silver powder fine mouth 19 parts Toluene 100 parts The above-mentioned mixture was rotated in a ball mill for 30 minutes, dissolved, and dispersed to prepare a surface layer coating material. . This coating was dry applied to a polyethylene-based electrical recording paper to a thickness of 1 μm. The volume resistivity of this surface layer was measured10 ¹¹
It was Ωcm. The electric record printing base paper created in this way was processed using a high-speed plate making machine (700 rpm, recording needle tip pressure 20
Although the plate was made in step g), there was no peeling of the surface layer at all. The plate-making properties are also good, and when the optical densities of the surface layer and the blackened area due to perforation were measured with a Macbeth densitometer, they were 1.18 and 1.46, respectively, which was sufficient contrast, and it was also very good visually. It had good readability. When this material was printed using a rotary transfer printing machine, a very clear image was obtained.

Claims (1)

[Claims] 1. A surface coating layer for electrical recording paper, which is characterized by containing leafing-type aluminum powder or brass powder.