JPH01249389A - Thermosensitive stencil paper - Google Patents

Abstract

PURPOSE:To prevent excess sticking by heating melting between a thermal head for the manufacture of stencil paper and thermosensitive stencil paper and allow manufacture of stencil paper using low energy by providing a very finely patterned sticking preventive layer which allows the thermal head to be brought into contact with it partially. CONSTITUTION:Substantial manufacture of stencil paper at low energy is possible by reducing the thickness of a thermosensitive stencil layer 3 consisting of a thermoplastic polymer-coated layer. A sticking preventive layer 4 is formed in a finely patterned shape at a proper interval on the surface of the thermosensitive stencil layer 3 of an entire original paper which travels in such a manner that a thermal head is brought into contact with the original paper partially, that is, only a part of the tip surface of the head establishes the contact, while the other section comes directly in contact with the thermosensitive stencil layer 3. As a result of forming this sticking preventive layer 4, the thermal head is brought into contact with only a part of the sticking preventive layer 4. Consequently, the energy required for the manufacture of stencil paper can be reduced. In addition, the excess sticking by heat melting between the thermal head and the thermosensitive stencil layer 3 is favorably prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat-sensitive stencil paper for writing with a thermal head, which is formed by providing a heat-sensitive stencil layer on one side of a porous thin material.

BACKGROUND ART Conventionally, heat-sensitive stencil paper has been manufactured by laminating a thermoplastic resin film and a porous thin material using an adhesive.

The heat-sensitive stencil paper produced by this method is made by perforating the heat-sensitive stencil layer made of the above-mentioned film by heating, and during printing, the base paper is wound around an ink drum, and the porous thin material side is Printing is performed by supplying ink from

It is desirable for the thickness of such a heat-sensitive stencil layer to be as thin as possible. By making the thickness thinner, the precision of plate making increases and printing becomes easier. This also makes it possible to use high viscosity ink, allowing for high density and clear printing. In other words, high-quality printing with good sensitivity and image quality can be performed.

However, with the conventional heat-sensitive stencil paper, there is a limit to how thin the heat-sensitive stencil layer can be made, and it is difficult to make the heat-sensitive stencil layer thinner.
It was difficult to make the thickness less than P, for example, about 1P.

Therefore, in order to solve this problem, it has been proposed that the heat-sensitive stencil layer to be provided on the porous thin-sheet material be composed of a coating layer of a thermoplastic polymer, thereby achieving the above-mentioned IMII. For example, in JP-A-6O-6719FI and JP-A-62-173296, a thermoplastic polymer solution is applied onto a releasable temporary support, and this is applied with or without an adhesive layer. discloses transfer to one side of a porous thin film material.

If the heat-sensitive stencil layer is composed of a coating layer of such a thermoplastic polymer, unlike the conventional method using a pre-formed film, there is no restriction in film-forming technology. , the thickness of the coating layer can be made considerably thinner, which makes it possible to achieve high quality printing.

[Problems to be Solved by the Invention] However, during digital plate making using thermal head writing, which has become popular recently, the thinned heat-sensitive stencil J1 may stick to the thermal head (the contact between the thermal head and the heat-sensitive stencil J1). (excessive fusion), resulting in deterioration of resolution.

For this reason, Japanese Patent Application Laid-open Nos. 60-78788 and 60-9
As disclosed in Publications No. 7891 and No. 61-102294, a stick prevention layer is provided on the entire surface of the stencil layer of the heat-sensitive stencil paper to suppress excessive heat fusion with the thermal head. Efforts are being made to prevent resolution deterioration.

However, the formation of this stick-preventing layer increases the thickness of the stencil layer, which results in insufficient perforation and problems such as a decrease in print density when using low-energy, low heat capacity plate making, which is desired during hot perforation. In order to avoid this problem, the stenciling energy of the thermal head must be increased.

Therefore, the present invention provides a heat-sensitive stencil paper that prevents excessive heat fusion between the thermal head and the heat-sensitive stencil paper during digital plate-making by thermal head writing, and also enables stencil printing with the thermal head to be performed with low energy. The purpose is to provide

Means for Solving the Problem 1 As a result of intensive studies to achieve the above object, the inventors have developed a heat-sensitive material consisting of a coating layer mainly composed of a thermoplastic polymer provided on one surface of a porous thin sheet material. When a stick prevention layer with a very fine pattern is provided on the surface of the stencil layer so that the thermal head for plate making partially contacts it, excessive heat fusion between the thermal head and the heat-sensitive stencil paper may occur. This invention was completed based on the knowledge that it is possible to prevent stickiness and that stencil printing using a thermal head can be performed with lower energy than a conventional stick-preventing layer provided on the entire surface of the stencil layer.

That is, the present invention provides a heat-sensitive stencil paper for thermal head writing, in which a coating layer mainly composed of a thermoplastic polymer is provided as a heat-sensitive stencil layer on one side of a porous thin sheet material. , relates to a heat-sensitive stencil paper characterized in that it is provided with a stick prevention layer in the form of a fine pattern with which the thermal head partially contacts.

[Structure and operation of the invention] Hereinafter, this invention will be explained in detail with reference to FIGS. 1 and 2.

FIG. 1 shows an example of the heat-sensitive stencil paper of the present invention, in which 1 is a porous thin material, 2 is an adhesive layer, and 3 is provided on one surface of the porous thin material 1 with an adhesive layer 2 interposed therebetween. A heat-sensitive stencil layer consisting of a coating layer mainly composed of a thermoplastic polymer,
Reference numeral 4 denotes a finely patterned anti-stick layer provided on the surface of the heat-sensitive stencil layer 3 so that the thermal head 5 for plate making partially contacts the surface of the heat-sensitive stencil layer 3.

The porous thin material 1 includes natural fibers such as manila hemp, kozo, and mitsumata, and polyester.

Synthetic fibers such as polyimide, and paper or nonwoven fabric made by mixing these fibers, with a basis weight of 5 to 15! /lrf, polyester fiber, silk screen gauze, etc.

The thermoplastic polymer applied to one side of the porous thin sheet material 1 may be any one that is non-adhesive and solid at room temperature in order to form the heat-sensitive stencil layer 3, such as acrylic resin, One or more kinds can be arbitrarily selected and used from a wide range of conventionally known polymers such as olefin resins and butyral resins.

These polymers may be a single polymer or a copolymer, and the copolymer is random.

It may be either a block copolymer or a graft copolymer. The molecular weight of the polymer varies depending on its type, but it is generally desirable that the weight average molecular weight is in the range of 20,000 to 200,000.

Particularly recommended polymers in this invention include thermoplastic polymers having hydroxyl and/or carboxyl groups in the molecule, and the use of such polymers provides good results in terms of printing sensitivity and printing durability. can be obtained.

The above hydroxyl group and/or carboxyl group may be present at the end of the molecule or at any position within the molecule (including the side chain).

Specific examples of such thermoplastic polymers include polyester resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate copolymers, polyether resins, polybutadiene resins, acrylic polyols, polyvinyl butyral, and polymers having hydroxyl groups. Examples include urethane-based or epoxy-based prepolymers, nitrocellulose, cellulose acetate flobionate resin, cellulose acetate phthalate resin, ethyl cellulose, and cellulose acetate.

In this invention, the above-mentioned thermoplastic polymer is provided as a coating layer on one surface of the porous thin sheet material 1.
At this time, various additives such as antioxidants, lubricants, plasticizers, and antistatic agents may be included in the coating layer as necessary. The content of these additives is 50% by weight or less of the entire coating layer. That is, the coating layer may not only consist of a thermoplastic polymer alone, but may also consist of this polymer as a main component, with an appropriate amount of the above-mentioned additives added thereto.

When forming the heat-sensitive stencil layer 3 consisting of a coating layer mainly composed of such a thermoplastic polymer, the above polymer is appropriately mixed with an organic solvent such as hexane, benzene, toluene, xylene, ethyl acetate, methyl ethyl ketone, or methyl isobutyl ketone. A polymer solution is prepared by dissolving the polymer in one or more of them.

In order to form a heat-sensitive stencil layer 3 consisting of a coated layer of this solution on one surface of the porous thin sheet material 1 via an adhesive layer 2 using such a polymer solution, for example, the above-mentioned polymer is placed on a temporary support. There is a method of applying a solution, adhering it to one surface of the porous thin sheet material 1 via an adhesive layer 2, and then peeling off the coating film from the temporary support.

As the adhesive used for the adhesive layer 2, known adhesives can be used depending on the materials of the heat-sensitive stencil layer 3 and the porous thin film material l. Specific examples include polyvinyl acetate resin, polyvinyl Examples include butyral resin, chloroprene, urethane resin, and acrylic resin.

The adhesive layer 2 contributes to improving the printing durability of the heat-sensitive stencil layer 3, but may be omitted depending on the case. In an embodiment in which the adhesive layer 2 is omitted, the heat-sensitive stencil layer 3 can be formed by applying the polymer solution directly onto the porous thin film material 1 filled with water and drying it, in addition to the method described above. methods can also be adopted.

The thickness of the coating layer as the heat-sensitive stencil layer 3 thus obtained is 2P or less, usually about 0.5 to 1.5 .mu.m. Since the thickness of the heat-sensitive stencil layer 3 made of a polymer coating layer can be made thin in this manner, plate making using low energy, which is one of the objects of the present invention, becomes substantially possible.

As shown in FIG. 1, the stick prevention layer 4 is in partial contact with the thermal head 5, that is, only a part of the tip end surface 5a of the head 5 is in contact with it, and the other part is in contact with the heat-sensitive stencil layer 3. A fine pattern is formed at appropriate intervals on the surface of the heat-sensitive stencil layer 3 over the entire area of the base paper that runs so as to be in direct contact with it.

By forming the stick prevention layer 4 in this manner, the thermal head 5 during stenciling comes into contact with only a portion of the stick prevention layer 4, so that the energy required for stenciling can be reduced. In addition, the thermal head 5
Excessive heat fusion between the heat-sensitive stencil layer 3 and the heat-sensitive stencil layer 3 is suitably prevented.

The size of the fine pattern forming the stick prevention layer 4 cannot be determined unconditionally depending on the density of the heating elements of the thermal head 5, its shape, and other factors, but the partial contact of the head 5 covers the entire area of the base paper. In order to achieve this, the area ratio of the stick prevention layer 4 on the surface of the stencil layer 3 is usually in the range of 10 to 50%, particularly preferably 15 to 40%, within any 100p angle on the surface of the stencil layer 3. It is better to do so.

When the above-mentioned occupied area ratio is lower than 10%, the thermal head 5 hardly comes into contact with the stick prevention layer 4, making it impossible to prevent excessive heat fusion between the thermal head 5 and the heat-sensitive stencil layer 3 during stencil printing. There is a possibility that the
If it is higher than %, the contact area between the thermal head 5 and the stick prevention layer 4 will be too large, resulting in a decrease in perforation performance in a low-energy stencil, so both are unfavorable.

Although various known methods can be used to form the stick prevention layer 4, for example, a method using a direct gravure coater is preferable as it allows coating in any desired pattern. In addition to this method, a method using a Mayer bar or the like can also be used.

The shape of the fine pattern of the stick prevention layer 4 may be, for example, a discontinuous pattern with diagonal lines in the longitudinal direction of the base paper as shown in FIG. 2, or a continuous pattern such as a lattice pattern. You can. The cross-sectional shape of each pattern is not limited to the illustrated rectangular shape, but can take various shapes such as a triangular shape like a pyramid pattern.

The thickness of the stick prevention layer 4 made of such a fine pattern is desirably the minimum thickness that does not cause the sticking phenomenon, and is usually 0.01 to 0.01.
0.3. If the film thickness becomes too thick, low-energy stencil printing by forming a fine pattern becomes substantially difficult.

As the material for the stick prevention layer 4, any material known for use in heat-sensitive stencil paper or heat-sensitive transfer recording media can be used. Specifically, silicone resin, fluorine resin, lubricant-containing heat Plastic resin and wax are used.

[Effects of the Invention] As described above, the heat-sensitive stencil paper of the present invention prevents the thermal head for plate-making from partially contacting the surface of the heat-sensitive stencil layer, which is composed of a coating layer mainly composed of a thermoplastic polymer, from sticking. By providing this layer, it is possible to prevent excessive heat fusion between the thermal head and the heat-sensitive stencil paper during digital plate making by thermal head writing, and also to allow the thermal head to perform stencil printing with low energy, resulting in improved resolution. A special effect can be achieved in that printed matter with excellent quality and high density can be obtained.

[Examples] Examples of the present invention will be described below to explain more specifically.

Example 1 Copolymer of vinyl chloride and vinyl acetate (composition ratio 88:1
2. A polymer solution consisting of 10 parts by weight of a polymer with a degree of polymerization of 800), 45 parts by weight of toluene, and 45 parts by weight of methyl ethyl ketone was coated on a temporary support made of a polyester film that had been subjected to mold release treatment with a silicone resin liquid, and the coating amount after drying. is 1.5fi! /nl with a Mayer bar and dried at 100°C for 1 minute to a film thickness of 1.
'2. A heat-sensitive stencil layer consisting of a thin polymer film was obtained.

Next, polyvinyl acetate resin (Nippon Gosei T-50) 20
An adhesive consisting of 80 parts by weight of toluene and 80 parts by weight of toluene was applied to the heat-sensitive stencil layer using a Mayer bar so that the coating amount after drying was 2 y/lri, and a basis weight of 99 y/lri was applied to the coated surface.
A porous thin film material made of Manila hemp thin film paper of /lri was laminated together, and after drying at 100° C. for 1 minute, the stencil layer was peeled off from the temporary support to obtain a heat-sensitive stencil paper.

Further, on the heat-sensitive stencil layer of the heat-sensitive stencil paper, silicone resin (Toray Silicon Co., Ltd. fM 5R-2411) 10
An anti-sticking coating liquid (coating liquid for abrasion prevention) consisting of 90 parts by weight of methyl ethyl ketone was coated with a gravure coater so that the area occupied was 40% and the thickness after drying was 0.
．． It was coated to a thickness of 1 μm to form a stick prevention layer.

Example 2 Polyvinyl butyral (16000C manufactured by Denki Kagaku Co., Ltd.) 1
1 part by weight of carnauba wax was placed on the surface of the heat-sensitive stencil layer of a heat-sensitive stencil paper prepared by carrying out the same treatment as in Example 1 except that a polymer solution consisting of 0 parts by weight, 40 parts by weight of toluene, and 50 parts by weight of methanol was used. An anti-sticking coating liquid containing 99 parts by weight of toluene was coated with a gravure coater so that the area occupied by the coating liquid was 20% and the thickness after drying was 0.
04. ” to form a stick prevention layer.

Comparative Example 1 A heat-sensitive stencil paper was prepared in the same manner as in Example 1 except that the anti-stick layer in Example 1 was not formed.

Comparative Example 2 Heat-sensitive stencil paper was prepared in the same manner as in Example 1, except that the stick prevention layer in Example 1 was formed on the surface of the heat-sensitive stencil layer so that its occupied area ratio was oO%. was created.

Next, the heat-sensitive stencil paper of Example 1.2 produced as described above and the heat-sensitive stencil paper of Comparative Examples 1 and 2 were stenciled with a thermal head using a thermal transfer recording word processor. I investigated the duplicating performance. The results are shown in Table 1.

Table 1 Also, when the stencil samples shown in Table 1 above were printed using a stencil printer AP9800 manufactured by Riso Kagakusha,
In the sample of Example 1.2, good printed matter with high density and excellent resolution was obtained, but in the sample of Comparative Example 1, deterioration in resolution was observed, and in the sample of Comparative Example 2, the print density was low. A decrease was observed.

[Brief explanation of the drawing]

FIG. 1 is a partially broken longitudinal cross-sectional view showing a schematic structure of a heat-sensitive stencil paper according to the present invention, and FIG. 2 is a perspective explanatory view showing a form of diagonal line pattern formation of the same stick prevention layer. l...Porous thin film material, 2 - Adhesive layer, 3... Heat-sensitive stencil layer, 4 - Stick prevention layer, 5... Thermal head patent applicant Nitto Electric Industry Co., Ltd. Figure 1 Figure 2 Figure 3 : ken51Jft! to

Claims (2)

[Claims] (1) In a heat-sensitive stencil paper for thermal head writing, in which a coating layer mainly composed of a thermoplastic polymer is provided as a heat-sensitive stencil layer on one side of a porous thin-sheet material, the above-mentioned thermal A heat-sensitive stencil paper characterized by being provided with a finely patterned anti-stick layer with which the head partially contacts. (2) The area occupied by the stick prevention layer on the surface of the heat-sensitive stencil layer is in the range of 10 to 50% in terms of occupied area ratio within any 100 μm square of the stencil layer, and the thickness is 0.01 to 0.
The heat-sensitive stencil paper according to claim 1, which has a diameter of 3 μm.