JPH03288694A - Base paper for thermal screen printing - Google Patents

Abstract

PURPOSE:To enhance dimensional stability and feed properties and to improve printing finish by constituting a porous support of a layer based on a natural fiber and a layer based on a synthetic fiber and providing a thermal layer to the surface of the layer based on the natural fiber. CONSTITUTION:For example, a layer having a wt. basis of 6g/m<2> is formed using a natural fiber based on Manila hemp. by a papermaking process and a layer having a basis wt. of 6g/m<2> is formed thereon using a polyester fiber by the same process to obtain a porous support of 12g/m<2> of basis weight. A polyester film of 2mum thickness is bonded to the surface of the natural fiber layer of the porous support by an adhesive composed of a vinyl chloride/vinyl acetate copolymer resin and a 0.2% MEK solution of a silicone resin is applied to the surface of the polyester film and dried to obtain base paper for thermal screen printing. Since one surface of the support is the layer based on the thermoplastic resin and the thermal layer is bonded to said layer and the porous layer based on the synthetic layer is provided to the surface opposite to the thermal layer in this base paper, the dimensional change difference of the surface and rear of the base paper due to the absorption and desorption of moisture is reduced and a curl is hard to generate and feed properties are improved. Further, the strength of the support itself is sufficient and the durability thereof in printing is also well.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a heat-sensitive stencil printing paper.

[Prior Art] A heat-sensitive stencil printing base paper is generally one in which a heat-sensitive layer is provided on the surface of a porous support. As the porous support, natural fibers such as manila hemp, kozo, and mitsumata, synthetic fibers such as polyester and nylon, and paper or nonwoven fabrics made by mixing these fibers, polyester fibers, silk screen gauze, etc. are used.

In addition, as a support proposed in the publication, polyester fibers with a circular or nearly circular cross section are used.
Thin paper containing more than 30% by weight of synthetic fibers (Japanese Patent Application Laid-Open No. 59-2896), porous support made of fine denier fibers (Japanese Patent Application Laid-Open No. 16793-1988), and synthetic fibers with a single fiber diameter of 8μ or less Thin paper (Japanese Unexamined Patent Application Publication No. 60-38193) made by blending and wet paper-making, basis weight 5-20 g /
l112 density 0.2 to 0.5 g/cn+'', wet area change rate 1.5% or less (Japanese Patent Application Laid-Open No. 81-2543
No. 96), porous thin paper made of natural fibers treated with viscose (Japanese Patent Application Laid-Open No. 62-92892), density 0.2-0.35 g/cmJ and density 0.30-0.50.
g/cI11'
-267094), etc. are known.

[Problems to be Solved by the Invention] When natural fibers such as manila hemp, kozo, mitsumata, etc. are used as a porous support, the heat-sensitive stencil printing base paper has a problem in that the porous support undergoes dimensional changes due to moisture absorption and desorption, etc. Because of this, it tends to cause curls. Therefore, conveyance defects may occur in a heat-sensitive stencil making device, a heat-sensitive stencil printing device, or an integrated device thereof. Further, there is a drawback that the heat-sensitive stencil paper tends to change in size and tear easily during printing. To deal with this, reinforcing methods such as adding, coating, or impregnating resin etc. are used, but these methods may not have sufficient strength or the resin etc. may block the minute holes in the porous support. This may cause problems such as deterioration of image quality, or it may not be sufficient.

Further, there are the following drawbacks when using synthetic fibers such as polyester and nylon.

Heat-sensitive stencil paper is weak and is prone to transport defects.

Synthetic fibers have low hygroscopicity, so they are easily charged with static electricity when used as base paper for heat-sensitive stencil printing, leading to poor conveyance due to sticking, and furthermore, in the case of a perforation method using a thermal head, there is a risk of destruction of the heating element. Furthermore, there is a risk that the porous support itself may shrink due to the heat generated during the production of heat-sensitive stencil printing base paper or the perforation during plate making.

This problem can be solved by coating the surface of the synthetic fiber with a heat-resistant resin or the like, but this increases manufacturing costs. Another problem is that white spots in the form of fiber grains are likely to occur on printed images.

In order to improve the above-mentioned drawbacks of natural fibers or synthetic fibers, examples using porous supports made of a mixture of natural fibers and synthetic fibers have been proposed. If the fiber content exceeds 20%, the fibers tend to stick out, resulting in poor image quality.In addition, in order to suppress dimensional changes due to moisture absorption and desorption, it is necessary to contain 60 to 80% or more of synthetic fibers. It cannot be a base paper for heat-sensitive stencil printing that is satisfactory.

In addition, in the above-mentioned Japanese Patent Application Laid-open No. 1-267094, a high-density support layer is newly added, but increasing the density significantly deteriorates image quality and dimensional changes due to moisture absorption and desorption are sufficiently satisfied. It's not a thing.

The present invention aims to solve the problems of the prior art. That is, the present invention provides a heat-sensitive stencil printing paper that has excellent dimensional stability, good transportability, and a good printing finish.

[Means for Solving the Problems] The present invention provides a heat-sensitive stencil printing base paper comprising a porous support and a heat-sensitive layer mainly made of a thermoplastic resin, in which the porous support is mainly made of natural fibers. The heat-sensitive stencil printing base paper is composed of a layer consisting mainly of synthetic fibers and a layer mainly composed of synthetic fibers, and the heat-sensitive layer is provided on the surface of the layer mainly consisting of natural fibers.

The layer mainly composed of natural fibers and the layer mainly composed of synthetic fibers may be bonded together during papermaking, or may be bonded together with an adhesive after each papermaking process. These may have a multilayer structure of two layers or three or more layers, but in either case, the heat-sensitive layer is provided on the surface of the layer mainly composed of natural fibers.

[Example] Next, examples and comparative examples will be described.

Example 1 Basis weight 6g/m using natural fiber mainly made of Manila hemp
2, and using polyester fiber, the basis weight is 6g/
M2 is made into paper (so-called paper combination), and the basis weight is L2g/m.
A porous support of No. 2 was obtained.

A polyester film with a thickness of 2 microns is adhered to the natural fiber side of this porous support with an adhesive made of vinyl chloride-vinyl acetate copolymer resin, and a silicone resin is applied to the surface of the polyester film. A 2% MEK solution was applied and dried to obtain a heat-sensitive stencil paper.

Example 2 Paper made using Manila hemp fiber, basis weight 6g/l1
A porous thin paper made of Manila hemp is used as a support, and a porous thin paper made of porous thin paper of No. 12 and a porous thin paper with a basis weight of Bg/m' made using polyester fibers is laminated with a vinyl chloride-vinyl acetate copolymer resin. A 2 micron thick polyester film was attached to the side of the tissue paper using vinyl chloride-vinyl acetate copolymer resin, and a 0.2% MEK solution of silicone resin was applied to the surface of the polyester film and dried. A heat-sensitive stencil paper was obtained.

Example 3 On the surface using the polyester fibers of Example 2, a porous thin paper having a thickness of 14 g/m 2 made from Manila hemp fibers was adhered using a vinyl chloride-vinyl acetate copolymer resin.

Comparative Example 1 Paper made using Manila hemp fiber, basis weight 12 g/m
The porous tissue paper No. 2 and a polyester film with a thickness of 2 microns were attached using a vinyl chloride-vinyl acetate copolymer resin, and a 0.2% MEK solution of silicone resin was applied to the surface of the polyester film, dried, and heat-sensitive. A base paper for stencil printing was obtained.

Comparative Example 2 A mixture of 10% Manila hemp and 90% polyester was prepared.
A porous thin paper with a basis weight of 12 g/m2 and a polyester film with a thickness of 2 microns were attached using vinyl chloride vinyl acetate copolymer resin, and a 0.2% MEK solution of silicone resin was applied to the surface of the polyester film. It was coated and dried to obtain a heat-sensitive stencil paper.

The results of testing the properties of the heat-sensitive stencil paper obtained in the above Examples and Comparative Examples are shown in the table.

Table O...Excellent ×...Poor O...Intermediate between O and △△...Intermediate between O and × [Effects of the Invention] The base paper for heat-sensitive stencil printing of the present invention has a support structure that is One side is a layer mainly made of thermoplastic resin, and a heat-sensitive layer is attached to this, and the opposite side of the heat-sensitive layer has a porous layer mainly made of synthetic resin, so that absorption on both sides is possible. Since there is little difference in dimensional changes due to dehumidification, etc., curling is less likely to occur and transportability is good. In addition, the support itself has sufficient strength and has good durability in printing (printing durability).

Claims (1)

[Claims] A heat-sensitive stencil printing base paper comprising a porous support and a heat-sensitive layer mainly composed of a thermoplastic resin, wherein the porous support is composed of a layer mainly composed of natural fibers and a layer mainly composed of synthetic fibers. A base paper for heat-sensitive stencil printing, characterized in that the heat-sensitive layer is provided on the surface of a layer mainly made of natural fibers.