JPH0251755B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD This invention relates to electrographic mimeograph paper. Conventionally, polyvinyl chloride film has been mainly used for electrical recording mimeograph films, but chlorine-based gases such as vinyl chloride and hydrogen chloride are generated during plate making, which gives off an unpleasant and irritating odor to people. There were problems with environmental hygiene and corrosion of the plate-making equipment. For this reason, many attempts have been made to use polyethylene in films based on chlorine-free resins such as polypropylene, polyethylene, polyester, and polystyrene due to its film formability and strength. When used as a recording mimeograph film,
Since the polyethylene film swells with the oils contained in the printing ink during printing, the film stretches, distorting the printed image, and causing excessive wrinkles on the film. In order to improve these drawbacks, various proposals have been made in the past, such as blending with other resins with good oil resistance, copolymerizing ethylene with other components to improve oil resistance, or using polyethylene from the beginning. In order to avoid problems caused by film elongation during printing, the elongation of the film due to printing ink must be 0.5.
% or less, preferably 0.3% or less,
At present, nothing suitable for practical use has yet been obtained. The present invention solves these drawbacks of the prior art, and has no unpleasant or irritating odor during plate making, and almost no elongation of the film due to ink during printing. That is, at a high temperature of 80 to 105°C, preferably 90 to 100°C, a film of a resin selected from polyolefin or polystyrene containing conductive fine powder is heated to 1.01°C.
Stretched to a low magnification of ~1.50 times, preferably 1.05 to 1.20 times, and cooled and set, internal strain tends to shrink (internal strain is latent strain,
It becomes apparent when heated or when it comes into contact with a solvent, plasticizer, etc. )
When the printing ink contacts and permeates the film, the latent internal strain is expressed and offset by the elongation caused by the printing ink. Therefore, the electrographic mimeograph paper using the film treated in this way has no unpleasant or irritating odor during plate making, and can suppress elongation due to printing ink to less than 0.3% during printing, resulting in less elongation during printing. there is no problem.
Furthermore, it is sufficient to use commercially available polyolefins, polystyrene, etc. as the resin for the film, and there is no need to add special resins or expensive additives, which is economically effective. However, if necessary, as long as it does not impair the effects of the present invention,
Some amount of additives or blending resins that are normally added to resins may be used. The stretching ratio is set to 1.01 to 1.50 times because if it is less than 1.01 times, there is almost no effect, and if it is more than 1.50 times, it tends to shrink too much when it comes into contact with printing ink, and netting occurs during stretching. Further, in order to perform the stretching stably and not to cause netting, it is more preferable to stretch the film by a factor of 1.05 to 1.20. Furthermore, it is necessary to carry out stretching at a high temperature, because when stretching is carried out at a temperature below room temperature, the effect of the present invention cannot be fully obtained because the low magnification as carried out in the present invention may be within the elastic limit of the resin. This is because it cannot be played. Note that although the effects of the present invention can be achieved even with uniaxial stretching, biaxial stretching is more preferable. The film may be stretched in a separate step and then laminated to the conductive mount by a known method, or the film may be laminated to the conductive mount immediately after stretching. Note that film stretching is sometimes carried out to increase strength, but in such cases, the stretching ratio is usually in the range of 3 to 10 times, and the desired effect of the present invention cannot be achieved. do not have. That is, at a stretching ratio of 3 to 10 times, the internal strain that tends to shrink is excessive, and the film shrinks too much during printing. Furthermore, the product tends to curl. Low-pressure polyethylene is particularly suitable as the resin used in the present invention in terms of its tendency to retain internal strain. The resins used in the present invention include polyolefins such as low-pressure, high-pressure, or medium-pressure polyethylene, ethylene-vinyl acetate copolymers, polypropylene, etc., and styrene resins such as polystyrene, styrene-butadiene copolymers, styrene-butadiene copolymers, etc.
Methyl methacrylate copolymers and blends thereof can be used. Further, as the conductive fine powder, conductive inorganic powder such as carbon black can be used. Examples of these formulations are as follows. Resin: 100 parts by weight Conductive powder: 5-40 parts by weight If necessary, the resin film of the present invention can contain mineral oils such as liquid paraffin.
If the content is too large, it becomes difficult to maintain internal strain, so in order to fully exhibit the effects of the present invention, the content should be 5% by weight or less, preferably 2% by weight or less ( (based on the total weight of the film including the mineral oil itself) is suitable. Further, the electrical resistance of the film of the present invention is preferably a volume resistivity of 10 ⁶ -10 ¹² Ω-cm. The thickness of the film is usually preferably 20 to 40 microns. Examples 1 to 4, Comparative Examples 1 to 4 The following resin raw materials were made into a film by an inflation method using a conventional method, and the stretched film was laminated with a conductive mount by a known method. It was used as an electrical record mimeograph. These plates were made into plates using "Toshya Fox SH-600" manufactured by Tokyo Aircraft Instruments Co., Ltd., and the plates were clear and there were no unpleasant or irritating odors during plate making. Furthermore, the plate made in this way was printed on a rotary mimeograph machine (manufactured by Dupro Co., Ltd., "Dupromate M-
760''), we conducted a printing test of 3,000 sheets each using medium-quality paper. The results are shown in the table below. Note that the vertical direction here refers to the vertical direction when the mimeograph paper is attached to the printing machine.
For raw film, this corresponds to the width direction. The lateral direction is a direction perpendicular to the longitudinal direction, and corresponds to the flow direction in the original film. In addition, in the case of a normal rotary mimeograph printing machine, due to its structure, the generation of wrinkles in the film during printing is largely influenced by the elongation in the lateral direction. In addition, as a comparative example, the results when a film similarly prepared by the inflation method was laminated to a conductive mount without any stretching operation, and the results when the stretching ratio was too high are also shown. Blend A Low pressure polyethylene 100 parts Carbon black 30 parts Blend B Low pressure polyethylene 100 parts Carbon black 20 parts Liquid paraffin 2.5 parts

[Table] Atsuta.
As mentioned above, when a film formed by a conventional method is used as it is (Comparative Examples 1 to 3), it stretches too much during printing and wrinkles occur, making it unusable as an electrical recording mimeograph paper. As shown in each example, those stretched at a low magnification under appropriate conditions have almost no elongation and no wrinkles. When uniaxially stretched as shown in Example 4, the elongation in the stretching direction is improved, but in the direction perpendicular to the stretching direction, the elongation tends to be slightly larger. Therefore, although uniaxial stretching as in Example 4 causes almost no wrinkles and poses no practical problem, biaxial stretching is more preferred in order to achieve the effects of the present invention more fully. Furthermore, as shown in Comparative Examples 1 and 2, even if the blowing ratio during film formation is increased, it does not have the same effect on elongation during printing as stretching does, but rather tends to increase elongation. In addition, an electrical recording mimeograph paper using the stretched film was subjected to aging tests at 60°C for two weeks and at room temperature for one year.
In all cases, the stretching effect was sufficiently maintained, and there were no problems caused by stretching during printing.

Claims (1)

[Claims] 1. A film made of at least one resin selected from polyolefin and styrene resin containing conductive fine powder, and stretched at a low magnification of 1.01 to 1.50 times at 80-105°C. Electric record mimeograph paper characterized by its use. 2. The electrographic mimeograph paper according to claim 1, characterized in that the film contains up to 5% by weight of mineral oil based on the total weight of the film. 3. The electrographic mimeograph paper according to claim 1, characterized in that the film contains up to 2% by weight of mineral oil based on the total weight of the film. 4. The electrical recording mimeograph paper according to any one of claims 1 to 3, characterized in that the resin is low-pressure polyethylene. 5. The electrographic mimeograph paper according to any one of claims 1 to 4, characterized in that the low-magnification stretching is biaxial stretching.