JPH0643150B2 - Heat-sensitive stencil paper - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a stencil sheet used for stencil printing, and more particularly to a heat-sensitive stencil sheet that allows a clear image to be punched at high speed with a thermal printer.

(Prior art and its problems) In conventional stencil printing, the original and heat-sensitive stencil sheet are superposed and irradiated with infrared rays, and the parts corresponding to the characters on the original absorb the infrared rays. A heat-sensitive method in which the plastic film of the base paper is melted and punched by heat to form a punched image, and the heat generated by the thermal printer head, which is composed of electric dot-shaped heating elements, allows direct punching without using the original. There is a thermal method for forming an image.

Conventionally, as these heat-sensitive stencil sheets, films such as polyvinyl chloride, polyvinylidene chloride, polypropylene, polyethylene terephthalate and the like and a porous support such as Japanese paper are used by adhering them. As a result of requiring a large output when perforating a film that has not been processed using infrared rays or a thermal printer head,
The heat also affects the periphery of the original image, and the perforated image is in a so-called "fluffy" state, resulting in a reduction in resolution.

Furthermore, since the resin melted by infrared rays or the thermal printer head is welded to the surface of the porous support, even though the film is perforated, the microscopic holes of the support sheet are blocked by the molten resin of the film. It also has a drawback that the ink is difficult to pass evenly, and the printed image becomes unclear.

On the other hand, in order to improve the above-mentioned drawbacks, a biaxially stretched heat-shrinkable film such as polyvinyl chloride, polyvinylidene chloride, polypropylene and polyethylene terephthalate and a porous support such as Japanese paper are used by adhering.

When the film is attached to the porous support sheet, the film covering the porous support sheet has heat shrinkage because the upper part of the micropores of the porous support sheet is not adhered and floats. When the film is used, heat is applied to the film to accelerate perforation due to the contracting force of the film.

On the other hand, the film of the portion other than the fine pores of the porous support sheet is fixed to the support sheet and therefore does not move even when contracted.

That is, when heat is applied to the film and the film on the micropores of the porous support sheet is perforated, the film around the perforation part contracts, the opening expands and the perforation progresses, but the micropores of the support sheet Since the film above the non-part is fixed to the support sheet, the holes do not expand further. Therefore, it becomes possible to perforate with a small output, so that the so-called "blunt" state is eliminated and the reduction of resolution is improved, and at the same time, the film and the porous support sheet are melt-heat-shrinked by the perforation in the adhered part which is not the porous part. Since the film is welded and the holes are not blocked, the ink passes uniformly, resulting in a clear printed image.

However, as described in JP-A-51-134213, a stencil sheet made of a conventional infrared irradiation type biaxially stretched heat-shrinkable film naturally shrinks even if heat is not applied. A new drawback arises in that the smoothness of the stencil sheet is impaired and perforation mistakes frequently occur.

(Object of the Invention) The present invention solves such a problem, and provides a heat-sensitive stencil sheet capable of forming a clear image at low speed and at high speed when punching using a thermal printer head. It is a thing.

(Summary of the Invention) As a result of intensive studies, the present inventors have achieved the above object by the following means.

That is, the present invention provides one side of a longitudinally uniaxially stretched thermoplastic resin having a draw ratio of 1.5 to 7 times, a longitudinal heat shrinkage of 10% or more, and a transverse heat shrinkage of 3% or less. The present invention relates to a heat-sensitive stencil sheet for a thermal printer, in which a porous support sheet is attached so that the longitudinal direction of the porous support sheet and the stretching direction of the uniaxially stretched film coincide with each other.

(Detailed Description of the Invention) The thermoplastic resin referred to in the present invention includes polyethylene, polypropylene, polymethylpentene, polyacetal,
Use of vinylidene cyanide, polyvinylidene fluoride, polyvinylidene fluoride, polyethylene terephthalate, polycarbonate, polysulfone, polyarylate, polyether ether ketone, polyether sulfone, polyamide, polyimide and their copolymers, and mixtures thereof. Can be done.

The thermoplastic resin longitudinally uniaxially stretched film used in the present invention is dipped in a silicone oil bath heated to a temperature of 20 ° C. or lower below the melting point or softening point for 3 minutes and then cooled to room temperature. Shrinkage rate is 10% or more,
It is preferably 15% or more, and the heat shrinkage in the lateral direction is 3%
It is preferably not more than 2%.

When the thermal shrinkage in the longitudinal direction is less than 10%, it is not possible to punch a clear image at low output, and high output is required, which results in so-called "futatsuta" perforation, and the shrinkage of the melted portion due to perforation is unsatisfactory. Since it is sufficient, the film that has been melted and heat-shrinked adheres to the porous portion of the porous sheet, and the holes are closed, so that a clear printed image cannot be obtained.

When the temperature at which the heat shrinkage rate is 10% or more is higher than the temperature 20 ° C. lower than the melting point or the softening point,
The periphery of the image perforated by the thermal printer head contracts, resulting in what is called "blunt" perforation.Because the film melts and heat contracts almost at the same time, it melts before the film on the hole moves. The film that has been melt-heat-shrinked is welded to the pores of the porous sheet, and a clear printed image cannot be obtained.

If the heat shrinkage ratio in the transverse direction exceeds 3%, the smoothness of the heat-sensitive stencil sheet is impaired due to the natural shrinkage of the film, resulting in frequent perforation errors.

The heat shrinkage rate in the present invention is calculated by the following formula.

A known method is adopted as the method for stretching the thermoplastic resin longitudinal uniaxially stretched film used in the present invention, but a roll stretching method for stretching in the longitudinal direction by the peripheral speed difference between the low speed roll and the high speed roll is preferable.

As will be described later, since the film used in the present invention is preferably an ultrathin film having a thickness of 5 μm or less, a laminated stretching method is preferred in which after laminating and stretching, peeling to obtain the intended thin film.

The stretching ratio is 1.5 to 7 times, preferably 2 to 6 times.

Further, the tensile elastic modulus measured by JIS K-7113 in the stretching direction is preferably 20,000 Kg / cm ² or more.

Stretching ratio and tensile modulus are less than 1.5 times, respectively, 2
If it is less than 10,000 kg / cm ² , wrinkles are likely to occur due to the elongation of the film and the perforated image tends to be unclear.

On the other hand, if the stretching ratio exceeds 7 times, the film is likely to tear in the step of attaching the porous support, which is not preferable.

The thermoplastic resin longitudinal uniaxially stretched film has a thickness of 0.5 to
10 μ, preferably 1 to 5 μ is desirable.

If it is less than 0.5 μm, the strength is reduced and the film is easily broken in the step of attaching the porous support, which is not preferable.

On the other hand, when it exceeds 10 μm, the perforation by the electric point heating element becomes insufficient and a clear perforation image cannot be obtained.
Furthermore, when it exceeds 10 μ, natural contraction in the vertical direction causes
It is not preferable because the smoothness of the heat-sensitive stencil sheet is easily impaired.

The porous support referred to in the present invention is a synthetic fiber such as polyester fiber, vinylon fiber, nylon fiber or the like, or a natural fiber such as Manila hemp, Kozo or Mitsumata, or a non-woven fabric of natural fiber.

The porous support sheet has a basis weight of 5 to 20 g / m ² and a thickness of 1
It is preferably 0 to 70 μm. If the basis weight or thickness of the porous support is less than 5 g / m ^{2 and} less than 10 μm, respectively, the porous support is likely to be broken in the step of attaching the film, which is not preferable. The basis weight or thickness is 20
If it exceeds g / m ² or 70 μm, the printing ink excessively enters the porous support and a clear printed matter cannot be obtained, which is not preferable.

The film uniaxially stretched in the longitudinal direction is attached so that the stretching direction and the longitudinal direction of the support sheet coincide with each other.

In the present invention, the longitudinal direction of the support sheet means the direction in which tension is applied in the step of attaching the support sheet, generally the flow direction of the support sheet.

Adhesion between the thermoplastic resin longitudinally uniaxially stretched film and the porous support sheet can be carried out by using an adhesive or by heat welding. When using an adhesive,
As the adhesive, an adhesive such as an acrylic adhesive, a vinyl chloride adhesive, a polyester adhesive, a vinyl acetate adhesive, or a rubber adhesive known as this type of adhesive can be used, and the adhesive is not particularly limited.

It is preferable to apply the adhesive so that the dry coating amount is 0.3 to 3 g / m ² .

As a method for adhering the thermoplastic resin longitudinally uniaxially stretched film and the porous support, it is preferable that an appropriate amount of the adhesive is applied to the film side, and then the porous support sheets are superposed and adhered and heated and dried.

In the present invention, the effect of natural shrinkage in the longitudinal direction is not expressed, in the attaching step of the film and the porous support sheet, the stretching direction of the film and the longitudinal direction of the porous support sheet are matched, Since the film is attached while applying tension in the longitudinal direction of the porous support sheet while preventing wrinkles from occurring, the direction of natural shrinkage of the film matches the direction of shrinkage due to relaxation of the tension in the longitudinal direction of the porous support sheet. It is estimated that this is due to

On the other hand, the film of the present invention does not impair the smoothness after sticking because the natural shrinkage in the lateral direction is small, but in the case of a biaxially stretched film that naturally shrinks in both the longitudinal and lateral directions, after sticking,
Since the film shrinks in the lateral direction due to the natural shrinkage, the smoothness is impaired.

When the heat-sensitive stencil sheet of the present invention is used, an electric point heater element is made to act on the surface of the thermoplastic resin longitudinal uniaxially stretched film to perforate the film to form a perforated image.
Next, the surface of the porous support is brought into contact with the printing ink supply surface of the rotary press to set so that the printing ink is absorbed and retained in the porous support, and the perforated image is formed from the perforation of the film to the surface of the printing paper that abuts the film. It can be printed by leaching as per the following.

(Effects of the Invention) As described above, when the heat-sensitive stencil sheet of the present invention is used,
With a thermal printer, it is possible to directly make a stencil sheet without using a document.

Further, the output of the thermal printer can be reduced, the head can be moved smoothly, and a clear image can be formed at high speed without accumulating deposits.

Hereinafter, the effects of the present invention will be described with reference to examples.

Example 1 Poly (vinylidene fluoride) [melting point 171 ° C., KYNAR (registered trademark) manufactured by Penwalt Co.] and polypropylene (Nobrene (registered trademark) manufactured by Mitsubishi Petrochemical Co., Ltd.) are coextruded on the front and back sides of the polyvinylidene fluoride. Then, after uniaxially stretching 5 times at 125 ° C., the polypropylene on both sides is peeled off, and the heat shrinkage rate in each of the machine direction and the transverse direction is 18% after the predetermined immersion process in which the immersion temperature of the oil bath is 140 ° C., A polyvinylidene fluoride thin film having a tensile elastic modulus in the stretching direction of 25,000 Kg / cm ² and a thickness of 4 μm measured at 1% according to JIS K-7113 was obtained. Acrylic adhesive (solids concentration 20%) was applied to the obtained film so that the dry coating amount was 1 g / m ² , and 80 parts of polyester fiber and 20 parts of Manila hemp were mixed to obtain the paper. Further, porous supports having a basis weight of 10 g / m ² and a thickness of 40 μ were superposed and heated and dried at 90 ° C. to obtain a heat-sensitive porous printing paper.

The obtained heat-sensitive stencil base paper was set in a thermal printer (PCPR 405) manufactured by NEC Corporation, and punched. At the time of perforation, low molecular weight substances did not adhere to the thermal head, and the thermal head moved smoothly. The obtained perforated image was clear with no erroneous markings or the like.

Using the perforated heat-sensitive stencil sheet as described above, printing was carried out by a Gesuttoner type Gess 420W rotary printing machine, and as a result, 3000 very clear printed materials were obtained.

(Comparative Example 1) The material used in Example 1 was coextruded in the same manner as in Example 1, uniaxially stretched at a stretching ratio of 1.5 times at 125 ° C, polypropylene on both sides was peeled off, and the mixture was heated to 160 ° C. Heat treatment while shrinking by 5% in the vertical direction, and the heat shrinkage rate in the vertical direction and the horizontal direction after the predetermined immersion treatment in the oil bath at 150 ° C. is 8% and 1%, respectively. %, A polyvinylidene fluoride thin film film having a tensile modulus of elasticity in the stretching direction of 19000 Kg / cm ² and a thickness of 4 μm as measured by JIS K-7113 was obtained.

When the porous support sheet was superposed on the obtained thin film under the same conditions as in Example 1, wrinkles were formed in the sticking step and in the thin film.

The obtained heat-sensitive stencil base paper was set in a thermal printer (PCPR 405) manufactured by NEC Corporation, and punched.

The perforated heat-sensitive stencil sheet was used to print with a Guess 420W rotary printing machine manufactured by Gestettner Co., Ltd. As a result, the printing ink did not pass uniformly and was unclear.

(Comparative Example 2) A porous support sheet was attached to a biaxially stretched polyethylene terephthalate film having a thickness of 3μ and a heat shrinkage rate at 160 ° C of 3.2% lengthwise and 2.5% widthwise under the same conditions as in Example 1. Then, a heat-sensitive stencil sheet was obtained.

The obtained heat-sensitive stencil sheet was set in a thermal printer (PCPR405) manufactured by NEC Corporation to perform perforation plate making.

Using the perforated heat-sensitive stencil sheet, printing was carried out by a Gesuttner Co., Ltd. Guess 420W rotary printing machine. As a result, the printing ink did not pass uniformly and it was unclear.

Example 2 Polycarbonate [softening point 230 ° C., Iupilon (registered trademark) manufactured by Mitsubishi Gas Chemical Co., Inc.] and polypropylene (Nobrene (registered trademark) manufactured by Mitsubishi Yuka Co., Ltd.) are coextruded on the front and back sides of the polycarbonate. 2.5 at 120 ° C
After being uniaxially stretched twice, the polypropylene on both sides is peeled off, and the heat shrinkage rates in the longitudinal direction and the transverse direction after the above predetermined immersion treatment at 160 ° C. are 55% and 1.5%, respectively, and JIS K-
The tensile elastic modulus in the stretching direction measured by
A polycarbonate thin film with a thickness of 00 kg / cm ² and a thickness of 5 μm was obtained.

A porous support was superposed on the obtained thin film under the same conditions as in Example 1 to obtain a heat-sensitive stencil sheet.

The obtained heat-sensitive stencil sheet was set in a thermal printer (PCPR 405) manufactured by NEC Corporation and punched.

The obtained perforated image was clear with no erroneous markings or the like.

Using the heat-sensitive stencil pierced paper which was perforated, printing was carried out by a Gesut Toner's Guess 420W rotary printing machine, and as a result, 3000 very clear printed materials were obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyasu Mizutani 1 Toho-cho, Yokkaichi-shi, Mie Prefecture Resin Research Laboratory, Mitsubishi Petrochemical Co., Ltd. (56) References JP-A-60-85996 (JP, A) JP 43-23713 (JP, B1) JP-B 47-1183 (JP, B1) JP-B 48-17370 (JP, Y1)

Claims (1)

[Claims] 1. A thermoplastic resin longitudinally uniaxially stretched film having a draw ratio of 1.5 to 7 times, a longitudinal heat shrinkage of 10% or more, and a transverse heat shrinkage of 3% or less. A heat-sensitive stencil sheet for a thermal printer, which is obtained by sticking a porous support sheet so that the longitudinal direction of the porous support sheet and the stretching direction of the uniaxially stretched film coincide with each other.