JPH01275097A - Heat-perforable stencil paper and production thereof - Google Patents

Abstract

PURPOSE:To obtain a stencil paper having excellent solvent resistance and thermal perforability, by incorporating fine particles having a specified softening temperature in a crosslinked adhesive layer. CONSTITUTION:This heat-perforable stencil paper has a crosslinked adhesive layer comprising thermoplastic fine particles having a softening temperature of lower than 150 deg.C, between a heat-shrinkage plastic film and an ink-permeable base. The thermoplastic fine particles preferably have a softening temperature as low as possible, and may be, for example, fine particles of a thermoplastic resin having a low softening point, particularly, one that has a low molecular weight, or a wax. The thermoplastic substance must be incorporated in the state of being finely dispersed in the crosslinked adhesive layer. For this purpose, the thermoplastic substance may be preliminarily pulverized and dispersed. Where the thermoplastic substance is soluble in a common solvent for the substance and the crosslinkable adhesive and can be finely dispersed in the adhesive, the thermoplastic substance may be simply mixed into a solution of the crosslinkable adhesive.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a base paper for thermal perforation printing and a method for producing the same.

[Prior art] Base paper for thermal perforation stencil printing, which is made by adhesively laminating a plastic film that is easily perforated by heating and a base material such as ink-permeable porous thin paper or gauze, is widely used for digital stencil printing machines. . The inks used in this type of printing press often contain relatively strong solvents in order to improve the abrasion resistance after printing and to dry quickly. Since peeling of the film may occur, crosslinking adhesives are often used to prevent this.

JP-A-61-118595 describes a base paper using a crosslinkable urethane adhesive. However, cross-linked adhesives are difficult to flow when heated, and when trying to obtain sufficient solvent resistance, they tend to inhibit thermal perforation. Because of the lack of performance, it has been extremely difficult to balance these two performances.

[Problems to be Solved and Attempted by the Invention] The present invention provides a base paper having excellent solvent resistance and excellent thermal perforation performance, and a method for producing the same.

[Means for Solving the Problems] The present invention provides a heat-perforated printing base paper in which a heat-shrinkable plastic film and an ink-permeable base material are bonded and laminated with an adhesive. The main method is to include plastic fine particles in a crosslinked adhesive layer.

The thermoplastic fine particles used in the present invention have a softening temperature of 150
It is preferable to have a softening temperature lower than 'C and as low as possible. For example, a thermoplastic resin with a low softening point, particularly a low molecular weight thermoplastic resin with a low softening point, a fine particle of wax, etc. can be used. These thermoplastic substances must be contained in a finely dispersed state in the crosslinked adhesive layer.

For this purpose, it is necessary to atomize and disperse the particles in advance.
Or, in the case of a substance that dissolves in the same solvent as the crosslinking adhesive and is dispersed and mixed in the adhesive in the form of fine particles,
The thermoplastic material may simply be mixed into the crosslinkable adhesive solution.

It is preferable that it is smaller than . Further, the amount of fine particles to be dispersed and mixed is preferably about 5 to 40% by volume added to the nonvolatile content of the adhesive. When added in such a proportion, the effect of the addition is clearly seen, and the adhesion is not significantly impaired. Adding too much, exceeding 40% by volume, tends to cause side effects such as decreased adhesion. Thermoplastic substances that can be suitably used include polystyrene resins, especially low molecular weight polystyrene resins, acrylic resins, especially low molecular weight acrylic resins, polyolefin resins, especially low molecular weight polyolefin resins,
Other various waxes can also be used. As the cross-linkable adhesive, urethane-based adhesives, epoxy-based adhesives, etc. can be used, but epoxy-based adhesives in particular do not cause variations in cross-linking and curing performance due to moisture, and can be used with alcoholic solvents. It is particularly preferred because it dries quickly and does not attack many shrinkable films.

[Function] The fine particles of the thermoplastic substance with a low softening point contained in the crosslinked adhesive do not reduce the crosslinking density of the adhesive itself, so they hardly impair the adhesiveness or solvent resistance. . It is thought that the fine particles are easily softened and deformed during thermal perforation, and it is presumed that they become a stress concentration point and facilitate the thermal deformation of the entire adhesive layer.

For this reason, there is very little interference with thermal drilling.

[Examples] Example 1 Alcon P70, which is a thermoplastic petroleum resin manufactured by Arayo Kagaku ■ and has a softening temperature of 70°C, is ground into fine particles together with isopropyl alcohol in a ball mill. This was finely dispersed in isopropyl alcohol to make a masterbatch. As a crosslinking adhesive, a mixture of epoxy resin AER330 ('25 age) manufactured by Asahi Kasei Shinko Co., Ltd. and Sanmide 300' (75 parts) manufactured by Sansho Kagaku Co., Ltd., a curing agent for epoxy resin, was dissolved in isopropyl alcohol. The previously prepared Alcon P70 masterbatch was added to form a mixture with a nonvolatile content of 15%, and a nonvolatile composition of 30% Alcon P70 and 70% crosslinkable adhesive.

The above mixture was coated on a heat-shrinkable biaxially stretched polyester film with a thickness of 2 microns at a non-volatile content of 1.5 g/d and dried to produce an ink-permeable Manila hemp thin paper with an ink permeability of 8.5 g/rrl'. After overlapping and gluing, 40
It was left to cure for 72 hours at °C.

On the base paper obtained in this way, Casio Word HW manufactured by Casio Computer Co., Ltd.
With the thermal head of the 100OJ S printer,
A good image was obtained when printing was performed at a density of 4 and at high speed using a printing press RISOGRAPH AP 7200 manufactured by Riso Kagaku Kogyo. The thermal head of commercially available word processors has relatively low output, and Casio Word HW100OJ
The output of S can be adjusted in 8 steps from density 8 on the high output side to density 1 on the low output side, and a satisfactory image can be obtained at density 4, which indicates that the paper has good perforation sensitivity. Ta.

When the ink was left on the base paper in this state for 24 hours and further printing was performed, more than 5,000 sheets were successfully printed. As a result, the original paper becomes
It has also been shown to have sufficient resistance to solvent components in ink.

Comparative Example 1 The same procedure as in Example 1 was carried out except that a mixture of crosslinkable resin components was used without blending Alcon P70 in the form of fine particles. When printed, the print was unclear at a density of 4, and was insufficient at a density of 8.

Example 2 In Example 1, the same operation as in Example 1 was carried out using Picolastic A75, a low molecular weight thermoplastic polystyrene resin manufactured by Exxon Chemical Co., Ltd. and having a softening temperature of 75° C., instead of Alcon P70. went. At a density of 4, a satisfactory image was obtained, and more than 5,000 sheets could be successfully printed after being left for 24 hours.

[Effects of the Invention] According to the present invention, the thermal perforation has good perforation sensitivity and can withstand printing on a large number of sheets even if the base paper is left with ink attached to it for a long time after being installed in a printing machine. A base paper for stencil printing is obtained.

Patent applicant: Asahi Kasei Industries, Ltd.

Claims (1)

[Claims] 1. For thermal perforation stencil printing having a crosslinked adhesive layer containing thermoplastic fine particles with a softening temperature lower than 150° C. between a heat-shrinkable plastic film and an ink-permeable base material. Base paper. 2. Production of base paper for thermal perforation stencil printing, characterized in that a heat-shrinkable plastic film and an ink-permeable base material are adhesively laminated using a crosslinking adhesive containing thermoplastic fine particles whose softening temperature is lower than 150°C. Method.