JP2001191659A - Base paper for thermal stencil printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate lowering with time of the surface smoothness of base paper for stencil printing wound up in the shape of a roll and thereby to provide the base paper for thermal stencil printing which causes no perforation fault even when printing is made by a model of high resolution, and thus enables attainment of a beautiful printed image. SOLUTION: This base paper for thermal stencil printing is constituted of a thermoplastic resin film and a porous substrate and the hardness of winding thereof on the occasion of being wound up in the shape of a roll is 30-80.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stencil sheet for heat-sensitive stencil printing which is perforated by a thermal head or a laser beam. The present invention relates to a heat-sensitive stencil printing paper that can prevent a reduction in the property.

[0002]

2. Description of the Related Art A heat-sensitive stencil sheet is made by laminating a porous support made of natural fibers or synthetic fibers to a thin thermoplastic resin film with an adhesive, and further applying a release agent for preventing sticking on the film surface. (See, for example, JP-A-57-182495 and JP-A-58-182495).
147396, JP-A-59-2896, etc.).

In the thermal stencil printing, a stencil master is prepared by perforating a thermoplastic resin film surface of a base paper having such a structure by heating a thermal head.

In recent years, thermal stencil printing has been required to further improve the image quality. In order to sharpen the printing of fine characters and the printing of photographs, the dot density of the thermal head is from 300 dpi to 400 dpi, and furthermore, 600 dpi.
And it is getting higher. In stencil making using such a thermal head with a high dot density, in order to perform accurate perforation, the surface of the heat-sensitive stencil printing base paper must have high accuracy,
Characteristics are required.

[0005] If irregularities are present on the surface of the heat-sensitive stencil printing paper, the state of adhesion between the film surface of the base paper and the thermal head will be poor, and there will be places that are easily perforated and places that are difficult to be perforated. There is a problem that the perforation is not performed and the image quality of the printed matter is deteriorated.

In order to solve such a problem, Japanese Patent Application Laid-Open No. 8-67081 specifies the surface roughness and smoothness of a thermoplastic resin film in a state where a porous support and a thermoplastic resin film are laminated. A base paper has been proposed. However, in order to supply the heat-sensitive stencil sheet to an actual printing press, the heat-sensitive stencil sheet is used as a roll-shaped heat-sensitive stencil sheet in which the base sheet is wound into a roll on a core such as a paper tube. Even if the surface smoothness of the heat-sensitive stencil printing base paper is good, when the base paper is wound up in a roll shape, the surface smoothness is reduced due to the winding pressure, and as a result, defective perforation occurs during plate making. there were.

As a method for solving the above problem, Japanese Patent Laid-Open No.
JP-A-239048 proposes a base paper in which the winding density of a roll is adjusted in order to prevent the surface smoothness of the base paper from lowering. Japanese Patent Application Laid-Open No. Hei 8-337069 proposes to use a roll-shaped stencil sheet having a specific compression elastic modulus. Further, JP-A-8-3370
No. 70 proposes a method in which a thermoplastic resin film and a porous support are attached to each other, calendered, and then wound into a roll.

[0008] However, although the roll-type heat-sensitive stencil printing paper described above has some improvement, it is still insufficient for use in a 600 dpi high-resolution printing press which has become mainstream in recent years.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the conventional heat-sensitive stencil sheet in roll form, and eliminates the deterioration of the surface smoothness over time of the stencil sheet roll-up. It is an object of the present invention to provide a heat-sensitive stencil sheet capable of printing a beautiful image without causing a perforation defect even when printing with a high-resolution model.

[0010]

The present invention employs the following means in order to solve the above problems. That is, the heat-sensitive stencil sheet of the present invention is a heat-sensitive stencil sheet comprising a thermoplastic resin film and a porous support, and has a winding hardness of 30 or more and 80 or less when wound into a roll. It is characterized by having.

[0011]

DETAILED DESCRIPTION OF THE INVENTION The present invention eliminates the above-mentioned problem, that is, a reduction in surface smoothness over time of a stencil sheet rolled up in a roll form, resulting in poor perforation even when printing on a high-resolution model. The stencil sheet for heat-sensitive stencil printing, which can print beautiful images without any problems, was studied diligently, and the hardness of the stencil sheet for heat-sensitive stencil wound in a roll was controlled to a specific range. It has been found that these problems can be solved all at once.

That is, according to the present invention, when wound up in a roll and used, the surface smoothness of the film surface of the base paper does not decrease, and even if printing is performed on a high-resolution model of 600 dpi, poor perforation occurs. And high-quality printing is possible.

That is, the heat-sensitive stencil sheet of the present invention has a winding hardness of 30 to 80, preferably 35 to 75, more preferably 40 to 70 when wound into a roll. It is important. When the winding hardness is less than 30, the winding appearance is easily disturbed,
It is not preferable because wrinkles are likely to occur during transportation in the printing press. On the other hand, when the winding hardness exceeds 80, the surface smoothness of the film surface of the base paper is remarkably reduced, resulting in poor perforation and defects such as white spots in a printed image, which is not preferable.

As the thermoplastic resin film in the present invention, a film made of polyester, polyamide, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, their respective copolymers, a blend thereof, or the like can be used. However, among these, a polyester-based film made of polyester, a copolymer thereof, or a blend thereof is preferably used. As such a polyester, a polyester containing an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid or an alicyclic dicarboxylic acid and a diol as main components is preferably used.

Here, as the aromatic dicarboxylic acid component, for example, terephthalic acid, isophthalic acid, phthalic acid,
1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,
4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid and the like can be used, and terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid and the like are preferably used. be able to.

As the aliphatic dicarboxylic acid component, for example, adipic acid, suberic acid, sebacic acid, dodecanedioic acid and the like can be used, and adipic acid is particularly preferably used.

Further, as the alicyclic dicarboxylic acid component,
For example, 1,4-cyclohexanedicarboxylic acid or the like can be used.

These acid components may be used alone or in combination of two or more. Further, an oxyacid such as hydroxybenzoic acid may be partially copolymerized.

The diol component includes, for example, ethylene glycol, 1,2-propanediol, 1,3-
Propanediol, neopentyl glycol, 1,3-
Butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-
Cyclohexane dimethanol, 1,3-cyclohexane dimethanol, 1,4-cyclohexane dimethanol,
Diethylene glycol, triethylene glycol, polyalkylene glycol, 2,2'bis (4'-β-hydroxyethoxyphenyl) propane and the like can be used. Among them, ethylene glycol is preferably used. These diol components may be used alone,
Two or more kinds may be used in combination.

The polyester used in the thermoplastic resin film of the present invention is preferably polyethylene terephthalate, a copolymer of ethylene terephthalate and ethylene isophthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, butylene terephthalate and ethylene. A copolymer of terephthalate, a copolymer of butylene terephthalate and hexamethylene terephthalate, a copolymer of hexamethylene terephthalate and 1,4-cyclohexane dimethylene terephthalate,
Copolymers of ethylene terephthalate and ethylene-2,6-naphthalate, blends thereof, and the like can be used. Particularly preferred are copolymers of ethylene terephthalate and ethylene isophthalate, polyhexamethylene terephthalate, hexamethylene terephthalate and 1,4-cyclohexane dimethylene terephthalate, copolymers of ethylene terephthalate and ethylene-2,6-naphthalate, and the like. Can be used.

The thermoplastic resin film of the present invention may contain, if necessary, an organic lubricant such as a flame retardant, a heat stabilizer, an antioxidant, an ultraviolet absorber, an antistatic agent, a pigment, a dye, a fatty acid ester, or a wax. An antifoaming agent such as polysiloxane can be blended. Further, lubricity can be imparted as required.

The method for imparting lubricity is not particularly limited, and examples thereof include clay, mica, titanium oxide,
Calcium carbonate, kaolin, talc, wet or dry silica, alumina, inorganic particles such as zirconia, acrylic acid, a method of blending organic particles having styrene or the like as a constituent, a catalyst to be added at the time of polyester polymerization reaction, A method using so-called internal particles can be employed.

The thermoplastic resin film of the present invention comprises:
Those stretched in at least one direction, more preferably biaxially, are preferably used. The stretching ratio is not particularly limited, but is preferably at least 2 times in each of the vertical and horizontal directions.

The thickness of the thermoplastic resin film in the present invention is preferably from 0.1 to 5 μm, more preferably from 0.1 to 3 μm, particularly preferably from 0.1 to 2 μm. .

The thermoplastic resin film preferably has a melting point of 230 ° C. or lower, more preferably 220 ° C. or lower, and particularly preferably 210 ° C. or lower. When two or more peaks of the melting point measured by the differential scanning calorimeter are present, it is preferable that at least one peak temperature is 230 ° C. or lower. Further, the lower limit of the melting point of the thermoplastic resin film is preferably at least 130 ° C. from the viewpoint of film forming stability.

The crystal melting energy of the thermoplastic resin film is preferably 5 to 50 J / g, more preferably 10 to 40 J / g.

The porous support in the present invention has a property of passing ink and does not substantially cause thermal deformation under heating conditions for perforating the film. In this respect, porous materials such as papermaking paper, nonwoven fabric, and screen gauze using natural fibers, synthetic fibers, inorganic fibers, and metal fibers as raw materials can be preferably used. Among them, those made of synthetic fibers are preferable, and those made of polyester fibers are particularly preferable in that the fiber diameter and the basis weight can be arbitrarily set. In addition, other fibers and the like can be used in combination as long as the effects of the present invention are not impaired.

The polyester used for the polyester fiber is mainly composed of an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid or an alicyclic dicarboxylic acid and a diol. Preferably, polyethylene terephthalate, polyethylene-2,6-naphthalate, poly-1,
4-cyclohexane dimethylene terephthalate, a copolymer of ethylene terephthalate and ethylene isophthalate, and the like can be used.

The fiber diameter of the porous support of the present invention is from 1 to 2
It is preferably within a range of 0 μm, more preferably 1 μm.
It is preferably from 15 to 15 μm, particularly preferably from 1 to 10 μm. The fiber diameter in the present invention refers to a diameter when the fiber is viewed perpendicularly from a plane formed by the base paper. The cross-sectional shape of the fiber is not particularly limited, and any cross-sectional shape can be used.

The basis weight of the porous support of the present invention is preferably from 1 to 20 g / m ² , more preferably from 3 to 15 g / m ² , particularly preferably from 4 to 12 g, from the viewpoint of ink retention.
g / m ² .

The fibers constituting the porous support of the present invention may contain, if necessary, a flame retardant, a heat stabilizer, an antioxidant, an ultraviolet absorber, an antistatic agent, a pigment, a dye, a fatty acid ester, a wax, etc. Organic lubricants or antifoaming agents such as polysiloxane may be blended, and if necessary, chemical treatment of the fiber surface with acid or alkali or corona treatment to impart affinity with the ink. , A low-temperature plasma treatment or the like may be applied.

The thermoplastic resin film of the present invention and the porous support may be bonded with an adhesive or may be bonded without using an adhesive.

The method for controlling the winding hardness of the heat-sensitive stencil sheet of the present invention within the scope of the present invention may be any method. For example, after the thermoplastic resin film and the porous support are bonded together, It can be achieved by adjusting the winding speed and the winding tension when winding on a paper tube or the like. Alternatively, in a case where the thermoplastic resin film and the porous support are attached to each other and wound on an intermediate spool and then slit and wound on a paper tube or the like, the unwinding tension, the winding tension, or the winding up is performed. This can be achieved by adjusting the speed. Further, in the case where the winding shaft of the slitter is not a tension control but a touch roll type, it can be achieved by adjusting the contact pressure of the touch roll.

It is preferable to apply a release agent to the film surface of the base paper in the present invention in order to prevent fusion with a thermal head or the like. As such a release agent, silicone oil, silicone resin, fluorine resin and the like can be used. Among these release agents, various additives are used as long as the effects of the present invention are not impaired, such as an antistatic agent, a heat-resistant agent, an antioxidant, organic particles, inorganic particles, and pigments. can do.

Before the release agent is applied, a corona discharge treatment or the like may be applied to the coated surface of the film in air or other various atmospheres, if necessary. <Measurement Method of Characteristics> (1) Roll Hardness The roll hardness of the heat-sensitive stencil sheet is measured using an Asker rubber hardness tester type C manufactured by Kobunshi Keiki Co., Ltd. in accordance with the spring-type hardness test of JIS K6301. did. As the measurement conditions, 110 m of the base paper was wound into a roll around a paper tube having an outer diameter of 44 mm and a length of 320 mm, and the measurement was performed at five places in the width direction of the roll-shaped heat-sensitive stencil sheet, and the average value was obtained and expressed. . (2) Fiber diameter (μm) Photographs were taken at an arbitrary magnification of 1000 times with an electron microscope at arbitrary 10 places of the porous support, and 10 fibers per one photograph were measured. The average value was determined and defined as the fiber diameter. (3) Weight (g / m ² ) The porous support was cut into a size of 20 cm × 20 cm, the weight was measured, and the weight was converted to the weight per 1 m ² to obtain the weight. (4) Film thickness (μm) Optical interference thickness gauge (HIT-25 manufactured by Toray Techno Co., Ltd.)
Was used to measure the film thickness at five locations in the width direction of the base paper, and the average value was calculated and represented. (5) Perforation The prepared base paper was supplied to a printing machine “RISOGRAPH” GR377 (600 dpi) manufactured by Riso Kagaku Kogyo Co., Ltd.
Plate making was performed using CHART No. 11 as a manuscript. Any five spots of the belt-shaped black solid portion of the plate-making master were observed at a magnification of 250 times with a microscope manufactured by KEYENCE CORPORATION, and the portions corresponding to the number of dots of the thermal head (513 per one observation point) were observed. The number of unperforated holes was counted, and the perforation rate (%) was calculated by the following equation.

Perforation rate = ｛(total number of observations−total number of unperforated) /
Total number of observations × 100% The judgment of the piercing property was indicated by を when the piercing rate was 95% or more, Δ when the piercing rate was 90% or more and less than 95%, and を when the piercing rate was less than 90%. Here, Δ and ○ are for practical use. (6) Evaluation of printability The prepared base paper was supplied to a printing machine “RISOGRAPH” GR377 (600 dpi) manufactured by Riso Kagaku Kogyo Co., Ltd.
Plate making was performed using CHART No. 11 as a manuscript, and 20 sheets were printed. The image of the twentieth printed sheet was visually observed for broken ruled lines and white spots in solid black portions, and the following judgment was made.

<Cut of Ruled Line> A ruled line without any break is represented by “○”, a ruled line with a slight cut is indicated by “△”, and a ruled line with severe cut is represented by “×”. Here, Δ and ○ are for practical use.

<White spots in solid black areas> A sample having no white spots is indicated by "O", a spot having a few white spots is indicated by "△", and a spot having significant white spots is indicated by "X". Here, Δ and ○ are for practical use.

[0039]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 Fabrication of Unstretched Nonwoven Fabric A polyethylene terephthalate raw material (intrinsic viscosity: 0.52, melting point: 254 ° C.) was spun by a melt blow method to prepare an unstretched nonwoven fabric having a fiber diameter of 9 μm and a basis weight of 105 g / m ² . The crystallinity of the unstretched nonwoven fabric is 3
% And birefringence were 0.002. (Film formation) Ethylene terephthalate-ethylene isophthalate copolymer containing 0.4% by weight of silica having an average particle size of 1.5 μm (isophthalic acid 14 mol% copolymer, melting point 21
6 ° C., intrinsic viscosity 0.69) was pre-crystallized in an oven at 120 ° C., and then dried under reduced pressure at 150 ° C. for 3 hours using a rotary drier. Using a 40 mm screw diameter extruder, the T die die temperature was 270. C. and extruded on a cooling drum to produce an unstretched film having a thickness of 25 μm.

The unstretched non-woven fabric is superimposed on the unstretched film and supplied to a multi-roll longitudinal stretching machine to provide a peripheral speed difference between the rolls so that the nip roll linear pressure is 1 N / c.
As m, the film was stretched 3.5 times in the longitudinal direction. Next, it is sent to a tenter type horizontal stretching machine, and heated to 95 ° C.
Then, the film was stretched 3.8 times in the width direction and heat-treated at 140 ° C. for 10 seconds, and then a silicone-based release agent was applied to the film surface to prepare a heat-sensitive stencil sheet.

The thickness of the obtained base paper was 55 μm, the film thickness was 1.8 μm, the basis weight of the nonwoven fabric was 8 g / m ² , and the fiber diameter was 5 μm.

Using a slit winder, the base paper was slit to a width of 320 mm with a winding shaft tension of 20 N and a winding speed of 50 m / min, and a length of 110 m was wound on a paper tube having an outer diameter of 44 mm. A heat-sensitive stencil sheet was prepared.

The roll hardness of the obtained roll-shaped heat-sensitive stencil sheet was 56.

Table 1 shows the results of evaluation of printability using this base paper. The printed matter printed using this base paper is
It was clear. Example 2 A roll-shaped heat-sensitive stencil sheet was prepared in the same manner as in Example 1 except that the tension of the unwinding shaft of the slit winder was changed to 10 N.

The roll hardness of the obtained roll-shaped heat-sensitive stencil sheet was 33.

Table 1 shows the results of evaluation of printability using this base paper. The printed matter printed using this base paper is
It was clear. Example 3 A roll-shaped heat-sensitive stencil sheet was prepared in the same manner as in Example 1 except that the tension of the unwinding shaft of the slit winder was set to 30 N.

The roll hardness of the obtained heat-sensitive stencil sheet for rolls was 77.

Table 1 shows the results of evaluation of printability using this base paper. The printed matter printed using this base paper is
It was clear. Example 4 A roll-shaped heat-sensitive stencil sheet was prepared in the same manner as in Example 1 except that the winding speed of the slit winder was 25 m / min.

The roll hardness of the obtained roll-shaped heat-sensitive stencil sheet was 44.

Table 1 shows the results of evaluation of printability using this base paper. The printed matter printed using this base paper is
It was clear. Example 5 A roll-shaped heat-sensitive stencil sheet was prepared in the same manner as in Example 1 except that the winding speed of the slit winder was changed to 100 m / min.

The roll hardness of the obtained roll-shaped thermosensitive stencil sheet was 62.

Table 1 shows the results of evaluation of printability using this base paper. The printed matter printed using this base paper is
It was clear. Comparative Example 1 A roll-shaped heat-sensitive stencil sheet was prepared in the same manner as in Example 1 except that the tension of the unwinding shaft of the slit winder was 5 N.

The roll hardness of the roll-shaped heat-sensitive stencil sheet thus obtained was 28.

When this base paper was supplied to a printing machine, wrinkles occurred and a normal printed matter could not be obtained. Comparative Example 2 A roll-shaped heat-sensitive stencil sheet was prepared in the same manner as in Example 1 except that the winding shaft tension of the slit winder was set to 40 N.

The winding hardness of the obtained roll-shaped heat-sensitive stencil sheet was 82.

Table 1 shows the results of evaluation of printability using this base paper. The printed matter printed using this base paper is
It was unclear.

[0057]

[Table 1]

As is clear from Table 1, Examples 1 to 5
Uses a heat-sensitive stencil sheet having a winding hardness of 30 or more and 80 or less when wound into a roll. Therefore, even when printed on a high-resolution model, the piercing rate is high and clear printed matter is obtained. was gotten. On the other hand, the base paper of Comparative Example 1 in which the roll hardness of the heat-sensitive stencil printing base paper when wound into a roll is less than 30 and the base paper of Comparative Example 2 in which the roll hardness exceeds 80 are low in perforation rate, The print was unclear.

[0059]

According to the present invention, it is possible to stably provide a heat-sensitive stencil sheet capable of obtaining high-quality printed matter without perforation defects even when printing on a high-resolution model.

Claims (2)

[Claims] 1. A heat-sensitive stencil sheet comprising a thermoplastic resin film and a porous support, wherein the roll has a hardness of 30 or more and 80 or less when wound into a roll. Base paper for stencil printing. 2. The heat-sensitive stencil printing paper according to claim 1, wherein said porous support is made of polyester fiber.