JPH03114785A - Manufacture of plate for thermal mimeograph - Google Patents

Abstract

PURPOSE:To improve a film opening-rate, the picture quality of printing, etc., by boring stencil paper for thermal mimeograph, in which a polyester film in thickness of 4mum or less is stuck to a porous support, while the conduction time of a thermal head is brought to 3.0ms or less. CONSTITUTION:A polyester film in thickness of 4mum or less is stuck to a porous support by adhesives or thermal adhesion, thus forming stencil paper for thermal mimeograph. The stencil paper for thermal mimeograph is bored while the conduction time of a thermal head is brought to 3.0ms or less, thus acquiring plate for thermal mimeograph. Porous thin sheet (a ceremony-thing note), porous synthetic-resin making paper, various nonwoven fabrics, a woven fabric, etc., can be used as said porous support. A thermal head for a line printer, a thermal head for a serial printer, etc., are employed as the thermal head.

Description

[Detailed Description of the Invention] [Technical Field] The present invention uses a method of drilling with a thermal head, instead of the conventional method of drilling in the image area by absorbing heat rays from a halogen lamp or xenon lamp. The present invention relates to a method for producing a plate for thermal stencil printing.

[Conventional method]

BACKGROUND OF THE INVENTION Stencil printing base papers that can be perforated by infrared irradiation have been known. A typical example is a thermoplastic synthetic resin film and porous thin paper bonded together using an adhesive. Furthermore, various synthetic resin films that can be perforated by infrared irradiation have been proposed. For example, in Japanese Patent Publication No. 4], -7623, propylene, polyamide, polyethylene, and vinyl chloride-vinylidene chloride copolymer are used, and in Japanese Patent Publication No. 47-1184, propylene, ethylene, butene-1, and isoprene are used. , tetramethylbutadiene and vinyl chloride
It is possible to use a copolymer with seeds and
No. 4969 describes the use of a vinyl synthetic resin film.

However, when stencil printing base paper is made using these synthetic resin films and then perforated with a thermal head for a thermal printer or thermal facsimile, the paper is hardly perforated and cannot be used for the desired thermal stencil printing. There is a problem that a plate cannot be obtained. This is infrared irradiation (tungsten halogen lamp, xenon lamp)
In the case of , the image area of the film receives a large amount of thermal energy, but in the case of a thermal head, the thermal energy is at most about 11 IIJ/dot, so this is thought to be due to the difference in heat capacity caused by the thickness of the film. .

Furthermore, when using the conventional perforation method using infrared irradiation, most of the synthetic resin films can be perforated up to a thickness of about 15 μm, but when using the perforation method using a thermal head, the perforation rate becomes extremely poor for thick films. Therefore, there is a problem in that the ink does not flow well through mimeograph printing, and as a result, the image density becomes low, resulting in only discontinuous images with broken line drawings.

In addition, base paper for heat-sensitive stencil printing is generally made by laminating a thermoplastic synthetic resin film and a porous support (tengucho paper, rayon mixed Japanese paper, nonwoven fabric, screen, etc.) with an adhesive resin. When a synthetic resin film or support material is expanded or contracted by heat, it curls in one direction due to the bimetal principle. In particular, the stretched synthetic resin film 11 shrinks due to temperature, time, etc., and curls toward the film side. It has been difficult to obtain a plate for thermal stencil printing using a thermal head.

On the other hand, in terms of the plate-making method for heat-sensitive stencil paper, the conventional perforation method using infrared irradiation requires a manuscript, and because the original and heat-sensitive stencil paper are overlapped and infrared rays are irradiated, 1-size contact plate-making is required. There are disadvantages in that the original after plate making is contaminated, and in the case of a copy where the original has countless thin toner particles scattered on the background, all of them are perforated, significantly deteriorating the printed image.

〔the purpose〕

The present invention has been made in view of the above-mentioned current situation, and its purpose is to enable digital plate making by thermal head perforation, increase film porosity and print image quality in thermal head perforation, and prevent curling of stencil paper. Another object of the present invention is to provide an industrially excellent method for manufacturing a plate for thermal stencil printing, which enables the fusion of a film to a thermal head and the reduction in the amount of perforation residue adhering to the thermal head.

〔composition〕

According to the findings of the present inventors, it has been found that, in addition to the melting point of the synthetic resin film, the heat capacity of the film controls the degree of perforation (porosity) when perforating stencil printing paper using a thermal head. It was done.

In other words, the heat capacity of the film is related to the thickness of the film, and the thinner the film, the more holes can be formed. However, most films other than polyester have a thickness of 10
At present, even the thinnest film that is industrially produced has a thickness of 4 to 6 μm. A film with a thickness of 4 μm or more has a very poor porosity even if the melting point is low. Also,
It was also found that films other than polyester are easily affected by temperature and humidity and have large expansion and contraction. Therefore, when it is laminated with a porous support to form a stencil printing base paper, curling is large due to temperature, humidity and aging. Furthermore, it has been found that the lower the melting point of the film and the thicker the film, the greater the fusion with the thermal head, and that the thicker the film, the more debris is attached. Therefore, when a certain level of energy (temperature) is applied to the thermal head to perforate the film, the higher the melting point of the film and the thinner the film, the more advantageous it is to prevent these phenomena. However, perforation will not occur unless the melting point of the film is lower than the temperature of the thermal head.

The present invention has been made based on these findings, and when producing a plate for heat-sensitive stencil printing, a base paper made by laminating a thermoplastic synthetic resin film and a porous support is used as a base paper, and Its thickness is 4 μ or less, preferably 1 to 3
The first feature is that a polyester film having a μ range is used.

As is clear from the above findings, the main reason for limiting the thickness of the polyester film to 4 μm or less is to improve the print image quality by increasing the film porosity in the thermal head perforation.

As the porous support used in the present invention, porous thin paper (tengucho), porous synthetic fiber paper, various woven fabrics, non-woven fabrics, etc. can be used. Further, the porous support and the polyester film can be bonded together with or without using an adhesive (eg, thermal bonding). Further, in order to prevent fusion (sticking) with the thermal head, an overcoat layer made of a surfactant or the like may be provided on the surface of the film after being applied to the laminate 1.

The second feature of the present invention is that a thermal head is used as the perforation means, and the energization time is limited to 3 ms.

Any known thermal head can be used, and specific examples include a thermal head for a line printer that prints using thermal paper or thermal transfer ribbon, and a thermal head for a serial printer. facsimiles, word processors, label printers,
Examples include those used in printing units such as CAD.

In addition, it is preferable to set the energization time by the thermal head within ms, preferably within 2 ms. If the 1° energization time exceeds 3 ms, the plate making time will become longer, the hole opening will deteriorate, and the thermal head Sticking with the surface becomes larger. If the sticking is large, slippage occurs in the feeding of the stencil paper, resulting in a decrease in image quality, poor transportability during plate making, and furthermore, poor dimensional reproducibility of printed images. When applying the same energy with a thermal head, these phenomena are more likely to be formed by increasing the power and increasing the head temperature rather than by increasing the current application time. Regarding sticking, when the head temperature is high, the temperature of the molten film increases and the tackiness decreases, and since the current application time is short, the plate making speed (line speed) is faster.
Sticking is small because the stencil paper is fed in steps with low adhesion.

On the other hand, if the power is reduced and the energization time is increased, the stickiness of the melt increases and the line speed decreases, so the melt is cooled, its temperature lowers, and the melt is fed in steps in an assimilated or solidified state. Therefore, sticking becomes large and a blocking phenomenon occurs.

Furthermore, if various anti-sticking layers are provided on the surface of the film to prevent this sticking, the running performance of the 8 head will be reduced, the surface of the thermal head will become scorched, and the perforation performance will be reduced.

For the above reasons, if the energization time exceeds 3 ms, the plate making time will become longer, the pore opening will deteriorate, and the amount of sticking will increase, so it is very difficult to select a sticking prevention method to prevent this. The intended purpose of the invention cannot be achieved.

〔Example〕

The present invention will be further explained below with reference to Examples, but the present invention is not limited thereto.

Example 1 A thin film was selected from various stretched thermoplastic synthetic resin films currently on the market, and a stencil printing base paper was prepared according to the following procedure.

Types of films used 7-rJl/A (7-110) Vinylidene chloride Vinyl chloride (hard) (soft) Vinyl chloride-vinylidene chloride copolymer polypropylene 7 Nylon 615 8 Polystyrene 309 Polyethylene (low pressure) 15 10 Polyacrylic 1- Lil 101
1 Polyester 624 32 Vinyl acetate-based adhesive is applied to the above various films using a wire bar, and porous thin paper (tengucho) with a thickness of 40 μm is layered and laminated by wet lamination to produce stencil printing base paper. did.

A thermal head (Ricoh Thermal Facsimile RIFAX5320
A thermal stencil is created by reading the document with H and writing with a thermal head (head energy 1, fixed at 0 mJ/dot), and printing with a mimeograph machine (Ricoh High Printer E80) to print various films. Applicability was evaluated.

The results are shown in Table 1 below.

From the above results, it is clear that even if the film has a low melting point, if the film is thick, the hole-opening performance is poor when the holes are formed using a thermal head. This is considered to be due to the heat capacity caused by the difference in thickness.

Example 2 Five types of polyesters having different thicknesses were laminated using a vinyl acetate adhesive (2 g/m2) on a 40 μm thick porous support made of Tengujo paper. A base paper for stencil printing was prepared by overcoating the surface of the laminated film with a polyoxyethylene alkyl phosphate surfactant to prevent sticking with the thermal head.

Samples Nα 4 to 9 1 1.5 2 3 3.0 4 3.5 4 Next, for these samples, the applied voltage (power) and energization time of the thermal spatula 2 1 were varied. The following results were obtained by investigating the relationship between the energy generated, the state of the pores (photographic observation), and the print quality.

Table 2 shows the results when the current application time was set to 3.0 ms, and Table 3 shows the results when the current application time was set to 2.0 ms.

In addition, Table 4 shows the degree of sticking when the stencil was made with an energizing time of 3.0 ms, and Table 1 and 5 show the degree of sticking when the energizing time was 2.0 ms.
The results of sticking are shown when s is set.

Table 2 Table 3 0 Good continuous holes and good print quality.

Δ The holes are discontinuously formed, and the line drawings in the printed image are broken like a dot pattern, but can be clearly identified.

X: The holes are not opened at all and ink cannot pass through.

Table 4 Table 5 0 No sticking @ Almost no sticking Δ Too much sticking From the above results, it can be seen that the perforation state of the stencil paper and the degree of sticking change depending on the thickness of the film and the energy of the thermal head. Recognize.

However, in reality, when applying the same energy (energy = power x time), it is better to increase the power (voltage) than to increase the energization time, and the output of the thermal head has a limit due to the head life. Yes (currently maximum 1
．． (about 5mJ/dot). Regardless of the above results, a polyester film with a thickness of 4 μm or less can achieve the desired effects of the present invention.

As described above, the digital plate making manufacturing method of the present invention, which uses a thermal head to perforate, has the following features: (1) A clear printed matter with no background stains can be obtained even from a copy document made by a PPC copying machine.

(2) Reduction, enlargement, editing, shading, position specification, etc. can be easily performed by simply performing image processing (signal processing).

(3) Even without a hard original, printed matter can be easily obtained from signal-processed image information. (It can be used as a printer.) (4) The plate making equipment can be made compact.

This method has significant advantages over plate-making methods that use infrared irradiation.

〔effect〕

The method of manufacturing a plate for thermal stencil printing of the present invention configured as described above has the following effects.

■ The perforations in the film are even and continuous, so when performing mimeograph printing, a continuous line drawing with excellent ink alignment can be obtained, and the image density in the solid image area is also high, resulting in excellent quality printing. Since it is possible to reduce the amount of sticking to the thermal head, it is easy to select a sticking prevention layer, and the conveyance during plate making is good, resulting in good dimensional reproducibility.

■ The stencil paper does not curl over time during the manufacture of plates for thermal stencil printing.

■ The lamination strength of the stencil paper is high (unlike polyolefin films, wet lamination or 1-ly lamination is possible without corona discharge treatment), so the resulting plate for thermal stencil printing has excellent durability. show.

Claims (1)

[Claims] (1) In a method of producing a plate for heat-sensitive stencil printing by perforating a base paper for heat-sensitive stencil printing with a thermal head, in which a plastic film is laminated to a porous support, a polyester film with a thickness of 4 μm or less is used as the plastic film. In addition, the thermal head energization time is 3.
．． A method for producing a plate for heat-sensitive stencil printing, characterized in that perforation is performed at a time of 0 ms or less.