JPS6359394B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a base paper for heat-sensitive stencil printing, which is a laminate of a film and a porous thin paper.

Conventionally, various types of porous thin paper for heat-sensitive stencil printing base paper, which is a laminate of a film and a porous thin paper, have been proposed.

For example, porous thin paper with a certain roughness containing up to 70 wt% of short fibers up to 10 denier based on bast fiber (Japanese Patent Publication No. 1982-8217), natural fibers containing 20 to 70 wt% of rayon or vinylon, etc. (Japanese Patent Publication No. 49-5933), those whose fiber surfaces are coated with viscose (Japanese Patent Publication No. 46-35707), and those whose fibers are impregnated with synthetic resin (Japanese Patent Publication No. 55-1982).
Publication No. 4799). In all of these conventional methods, a thin film is laminated with natural fibers such as bast fibers, synthetic fibers, or semi-synthetic fibers of about 1.5 denier or more, or a mixture thereof, to provide strength. However, those using porous thin paper as the base paper can be superimposed on the original manuscript.
When xenon flashing was used, there were problems with light transmittance and scattering, resulting in thick prints, poor resolution, and poor clarity compared to the original manuscript.
This phenomenon occurs because the paper is laminated with porous thin paper that originally blocks light. That is, it is thought that more energy than necessary must be given to the xenon flash in order to increase the amount of light transmission, and furthermore, because the fiber density is low, the perforations tend to expand to where the fibers are. Therefore,
To reduce the amount of porous thin paper as much as possible,
The conditions for obtaining good printed matter are to increase the density of the fibers and to minimize the spread of the perforations.

FIG. 1 is an enlarged conceptual diagram of a base paper for thermal stencil printing. Fibers 1 are entangled with each other, and a thin film 2 is pasted thereon. When a document is superimposed on the base paper for thermal stencil printing having this structure and xenon flashed, a portion of the film 2 corresponding to the black portion of the document is perforated to form a perforated portion 3. Originally, the perforation 3 should have a shape surrounded by imaginary lines, but in reality, the perforation is caused by shrinkage of the film, resulting in a thickening 4. In severe cases, the entire area surrounded by fibers 1 will be perforated. Therefore, in order to reduce the thickness 4, it is sufficient to make the area surrounded by the fibers 1 extremely small to prevent the film from expanding due to shrinkage. In fact, in some cases, good results have been obtained by using polyester mesh (150 to 200 mesh) as a support for supporting the film. However, such fine meshes, including polyester meshes with 150 to 200 meshes, are too expensive to be widely used.

Therefore, we decided to use paper as the support and laminate it with the lowest possible basis weight. The smaller the basis weight, the fewer fibers there are in the paper and the better the light transmittance. However, since the paper used for this is all produced using a wet process, the current limit is about 8 g/m ² .
Moreover, since fibers of 1.5 denier (hereinafter abbreviated as d) or more are used, the fibers are thick and there is a limit to the improvement of light transmittance.

From the above, in order to more faithfully reproduce the original manuscript, it is necessary to have high strength even if the basis weight is small, fibers with a small diameter and high light transmission, and fibers with high density and no spread of perforations. It can be seen that it is sufficient to use a base paper for heat-sensitive stencil printing in which a thin film is laminated with a support that satisfies the problem of the absence of such defects.

In view of the above points, the present invention uses a porous thin paper with a small basis weight using extremely thin fibers of 0.1 denier or less, which is not generally used as a raw material for thin paper, as a support, and a thin film is attached to this paper. They are pasted together to form a base paper for thermal stencil printing. By using fibers of 0.1 denier or less, the fiber density can be extremely increased even though the basis weight is small, resulting in high strength and no thickening of the perforated area.
Moreover, the light transmittance is improved due to the small basis weight.
Furthermore, if the degree of dispersion of the fibers is good, the base paper for heat-sensitive stencil printing can be made without partial light shielding.

A detailed explanation will be given below using examples.

Example 0.03D polypropylene paper (10g/m ² , 8g/m ² , 5g/m ² ,
Prototype manufactured by Tonen Petrochemical Co., Ltd.) was used as a porous support.
3μ polyester film (Torel Mirror #3)
was laminated with polyvinyl acetate as an adhesive. In terms of strength, all of them were strong and had no problems.

When these were used as base paper to make plates using a heat-sensitive flash plate-making machine, the results were extremely clear and without thickening, and the resolution was greatly increased compared to conventional base paper. Even with a basis weight of 10 g/m ² , the resolution is higher than that of base paper using a conventional porous support, which proves that the perforations are less thick due to the higher fiber density. However, at 10 g/m ² , there was a slight amount of blurring due to insufficient plate making, and a smaller basis weight was preferable. This is thought to be because the density of the fibers is so high that there are areas with poor dispersion that block light. Therefore, there is no problem with strength, and although it is difficult with current technology, by using a material with a low basis weight and good dispersion as a support, resolution can be further improved and the original manuscript can be copied more faithfully. It seems possible to do so. In order to clearly bring out the above effects compared to the current commercially available base paper for thermal stencil printing, which is made of porous thin paper made of fibers of 1.5 denier or more and laminated with a thin film as a support, it is necessary to , if the fiber diameter is about 1/2 of 1.5 denier, it will not be noticeable, but at least 1/10
It is necessary to use a porous thin paper using fibers (fine denier fibers) of a certain degree, preferably 0.1 denier or less, as a support.

By laminating a porous base paper for heat-sensitive stencil printing, which is laminated with a porous thin paper made of fine denyl fibers as described above, with a film, a base paper for heat-sensitive stencil printing with good resolution can be obtained.

In addition, as fine denier fibers other than the examples, there are nylon type (0.03 d) manufactured by Tonen Petrochemical Co., Ltd. and rayon type (0.01 d) manufactured by Toray Industries. In principle, it is believed that a stencil printing paper with good resolution can be obtained. As described above, by using the base paper for thermal stencil printing of the present invention, printed matter with high resolution and excellent clarity can be obtained using a light printing machine more easily than offset printing, etc., and is extremely useful industrially. be.

[Brief explanation of drawings]

The figure is an enlarged conceptual diagram of base paper for thermal stencil printing. 1...Fiber, 2...Film, 3...Perforation part,
4...I'm overweight.

Claims (1)

[Claims] 1 A base paper for heat-sensitive stencil printing made by laminating a thin film to a porous thin paper made of a nonwoven fabric with a basis weight of 8 g/m ² or less and made of synthetic fibers of 0.1 denier or less.