JP2001080228A - Base paper for thermal stencil printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To print a beautiful image from a first sheet even by printing by a high resolution type printer without changing a density of an image even by printing in a large quantity, by setting a pressure loss of the air in a porous support to a specific value. SOLUTION: In a porous support, a pressure loss of an inner air is set to less than 5 mmAg, preferably 4 mmAg or less or more preferalby 3 mmAg or less. If the loss of the air is 5 mmAg or more, a permeation resistance of an ink is increased. When printed by a high resolution type printer, a density of an image at initial several sheets becomes insufficient, and stable printed product cannot be obtained. A method for setting the resistance of the air to less than 5 mmAg includes the steps of mixing fibers of two or more types having different fiber diameters, regulating a crest amount or regulating a pressing pressure after papermaking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive stencil sheet which is formed by a thermal head, a laser beam, or the like without a change in image density in mass printing or an initial defective image in high-quality model printing. .

[0002]

2. Description of the Related Art Conventionally, heat-sensitive stencil printing paper used has a laminated structure in which a porous support made of a natural fiber or a synthetic fiber is adhered to a thin thermoplastic resin film with an adhesive. JP-A-57-18249
No. 5, JP-A-58-147396, and JP-A-5-147396.
No. 9-2896).

[0003] Thermosensitive stencil printing is a method in which a thermoplastic resin film surface of a base paper having such a structure is subjected to heat perforation stencil making, and an ink holding layer comprising a mesh screen composed of resin fibers or metal fibers on a porous support body. The plate-making master is wound around a rotatable plate cylinder having ink, ink is supplied from an ink supply unit provided inside the plate cylinder, and the printing paper is continuously pressed by a pressing unit such as a press roller. Thus, printing is performed by oozing ink from the plate cylinder opening and the master perforated portion.

In recent years, a thermal stencil printing apparatus has a thermal element density of 400 to prevent a copier or light printing from being performed.
The resolution has been increased from 600 dpi to 600 dpi. As a heat-sensitive stencil printing base paper for this purpose, for the purpose of improving image quality, a base paper having a structure without using an adhesive has been proposed (JP-A-6-305273, JP-A-7-186565, etc.). Further, in order to improve the adhesion to a thermal head, a porous support made of a thermoplastic resin fiber to reduce the fiber diameter has been proposed.

However, printing on a high-resolution model using the above-described heat-sensitive stencil printing base paper requires about ten discarded prints in order to stabilize the printed image, resulting in a waste of ink and paper. there were.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the conventional heat-sensitive stencil printing paper, and the image density does not change even when a large number of sheets are printed. It is an object of the present invention to provide a heat-sensitive stencil sheet capable of printing a beautiful image from the first printed matter even when printing.

[0007]

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 consisting of a thermoplastic resin film and a porous support, wherein the pressure loss of air inside the porous support is less than 5 mmAq. It is a feature.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention has been made to solve the above problem, that is, the image density does not change even when a large number of sheets are printed, and the first printed matter is beautiful even when printing on a high resolution model. The stencil base paper for heat-sensitive stencil printing capable of printing an image was studied diligently, and as a porous support constituting the base paper for heat-sensitive stencil printing, a specific pressure loss of air inside the support was used. Surprisingly, the present inventors have sought to solve such a problem at once and completed the present invention.

That is, the base paper of the present invention has a porous support having a pressure loss of internal air of less than 5 mmAq, preferably 4 mmAq or less, more preferably 3 mmAq.
It is important to use one having Aq or less. If the pressure loss of the air is 5 mmAq or more, the transmission resistance of the ink becomes large, and when printing with a high resolution model, the image density of the first few sheets becomes insufficient, and a stable printed matter cannot be obtained, 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, a copolymer thereof, or a blend thereof is used. be able to. Among these, a polyester film comprising a polyester, a copolymer thereof, and 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 among them, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid and the like are preferable. Can be used.

Further, as the aliphatic dicarboxylic acid component,
For example, adipic acid, suberic acid, sebacic acid, dodecanedioic acid and the like can be used, and among them, adipic acid and the like can be preferably used.

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

These acid components may be used alone.
Two or more kinds may be used in combination, and further, an oxyacid such as hydroxybenzoic acid may be partially copolymerized.

As the diol component, 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.

As specific examples of the polyester used for the thermoplastic resin film of the present invention, polyethylene terephthalate, a copolymer of ethylene terephthalate and ethylene isophthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, butylene terephthalate, Copolymer of ethylene terephthalate, copolymer of butylene terephthalate and hexamethylene terephthalate, hexamethylene terephthalate and 1,4
-Cyclohexane dimethylene terephthalate, ethylene terephthalate and ethylene-2,6-naphthalate, and blends thereof. Particularly preferred are copolymers of ethylene terephthalate and ethylene isophthalate, polyhexamethylene terephthalate, hexamethylene terephthalate and 1,4-cyclohexane dimethylene terephthalate, and copolymers of ethylene terephthalate and ethylene-2,6-naphthalate. Can be used.

If necessary, the thermoplastic resin film may contain 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, or a polysiloxane. And the like can be blended. Further, lubricity can be imparted as required.

The method for imparting lubricity is not particularly limited, but examples thereof include clay, mica, titanium oxide, calcium carbonate, kaolin, talc, inorganic particles such as wet or dry silica, alumina, zirconia, acrylic acids, and styrene. And the like, and a method using so-called internal particles for precipitating a catalyst and the like to be added during the polyester polymerization reaction.

The thermoplastic resin film of the present invention comprises:
Preferably stretched at least uniaxially,
More preferably, it is a biaxially stretched film. 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 0.1 to 5 μm, more preferably 0.1 to 5 μm.
It is 1 to 3 μm, particularly preferably 0.1 to 2 μm. The melting point of such a thermoplastic resin film is preferably 230
C. or lower, more preferably 220.degree. C. or lower, particularly preferably 210.degree. C. or lower. When two or more peaks of the melting point measured by a differential scanning calorimeter are present, those having at least one peak temperature of 230 ° C. or lower are preferably used. Further, the lower limit of the melting point of the thermoplastic resin film is 130 ° C. from the viewpoint of film forming stability.
It is preferable that this is the case.

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 of the present invention can be used as long as it has an ink-passing property and does not substantially cause thermal deformation under heating conditions under which a film is perforated. In terms of its meaning, in terms of ink retention and uniform dispersibility, fiber structures made from natural fibers, synthetic fibers, inorganic fibers, metal fibers, and the like, for example, porous materials such as papermaking paper, nonwoven fabric, and screen gauze Can be preferably used. Above all, a fiber structure composed of synthetic fibers is preferable in that the fiber diameter and the basis weight can be arbitrarily set, and those composed of polyester fibers are more preferably used. In addition, other fibers and the like may be used in combination with such a fiber structure as long as the effects of the present invention are not impaired.

The polyester used for the polyester fibers constituting the fibrous structure 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 fiber constituting the porous support is preferably in the range of 1 to 20 μm, more preferably 1 to 15 μm, particularly preferably 1 to 10 μm.
It is. In addition, the fiber diameter referred to in the present invention means 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 from the viewpoint of ink retention.
g / m ² .

The fibers constituting the porous support of the present invention may contain, if necessary, flame retardants, heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, pigments, dyes, fatty acid esters, waxes, 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. , Low-temperature plasma treatment or the like.

The thermoplastic resin film of the present invention and the porous support may be bonded to each other by using an adhesive, or may be bonded without using an adhesive, for example, by heat fusion. can do.

The method for controlling the pressure loss of air within the porous support used in the base paper of the present invention within the scope of the present invention is as follows.
Any method may be used. For example, in the case of papermaking such as tissue paper, two or more fibers having different fiber diameters are mixed, the basis weight is adjusted, and the press pressure after papermaking is adjusted. You may. In the case of a nonwoven fabric such as a synthetic fiber, it is preferable to adjust the fiber diameter and the basis weight, or to adjust the calender pressure after spinning to adjust the thickness of the nonwoven fabric. When a porous support is produced by biaxially stretching an unstretched nonwoven fabric such as polyester fiber, the basis weight and fiber diameter of the unstretched fiber are adjusted, the stretching ratio is adjusted, and the calender after stretching is adjusted. Adjusting the pressure is also effective.

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. Silicone oil,
Silicone resin, fluorine resin, or the like can be used. In these release agents, various additives can be used in combination as long as the effects of the present invention are not impaired. For example, an antistatic agent, a heat-resistant agent, an antioxidant, organic particles, inorganic particles, a pigment, and the like can be used.

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.

[0031]

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. The evaluation in the examples is based on the following measurement method. <Method of measuring characteristics> (1) Pressure loss of air The pressure loss was measured by preparing a sample for measurement by cutting a porous support into a circular shape having a diameter of 13.2 cm. It is sandwiched between two donut-shaped steel plates (1 mm thick) having an inner diameter of 5.8 cm, sealed so as not to leak air in the lateral direction, and set in a pressure loss measuring device for an air filter, and has a diameter of 5.8 cm. Flow rate 1
000 cm ³ / cm ² · min air flow, and the pressure difference between the entrance and exit of the sample is measured using a differential pressure gauge (Yamamoto ELECTRIC
MANKS (manufactured by WARKS). (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 photographs were taken for one photograph.
The diameters of fifty fibers in total were measured, and the average value was determined 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 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 determined. (5) Evaluation of printability The prepared base paper was supplied to a printing machine “Risograph” GR377 (600 dpi) manufactured by Riso Kagaku Kogyo Co., Ltd.
Perform plate making using CHART No. 11 as a manuscript, print 20 sheets, and visually observe the first image of the printed image for the interpretation of 5-point kanji, broken ruled lines, and white spots in black solid areas.
It was determined as follows.

<Comprehension of 5-point Kanji> Those that can be completely interpreted are marked with “○”, those that can be interpreted somehow are marked with “△”, and those that cannot be interpreted are marked with “x”. Δ and ○ are for practical use.

<Cleaning of Ruled Lines> A ruled line without any break was marked with “○”. A ruled line with a slight cut was marked with “△”. Δ and ○ are for practical use.

<Blank spots in solid black area> A blank spot is indicated by "O", a spot having a slight blank spot is indicated by "△", and a blank spot is marked by "X". Δ and ○ are for practical use. Example 1 Fabrication of Unstretched Nonwoven Fabric A raw material of polyethylene terephthalate (intrinsic viscosity 0.50, melting point 255 ° C.) was spun by a melt blow method to prepare an unstretched nonwoven fabric having a fiber diameter of 8 μm and a basis weight of 130 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
8 ° C., intrinsic viscosity 0.70) 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. C. and extruded on a cooling drum to produce a 20 μm thick unstretched film.

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 3.7 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 50 μm, the film thickness was 1.7 μm, the basis weight of the nonwoven fabric was 10 g / m ² , and the fiber diameter was 4 μm. The film portion of the base paper was carefully peeled off to separate only the porous support, and the pressure loss of the air of the porous support was measured to be 2.8 mmAq.

Table 1 shows the results of evaluation of printability using this base paper. The first printed matter printed using this base paper was clear. Example 2 In Example 1, the basis weight of the unstretched nonwoven fabric was 180 g / m.
^A stencil sheet for heat-sensitive stencil printing was prepared in the same manner as in Example 1 except that the number was changed to ² .

The thickness of the obtained base paper was 60 μm, the film thickness was 1.7 μm, the basis weight of the nonwoven fabric was 14 g / m ² , and the average fiber diameter was 4 μm. The film portion of the base paper was carefully peeled off to separate only the porous support, and the pressure loss of air in the porous support was measured.
Aq.

Table 1 shows the results of evaluation of printability using this base paper. The first printed matter printed using this base paper was clear. Comparative Example 1 In Example 1, the basis weight of the unstretched nonwoven fabric was 200 g / m.
^A stencil sheet for heat-sensitive stencil printing was prepared in the same manner as in Example 1 except that the number was changed to ² .

The thickness of the obtained base paper was 80 μm, the film thickness was 1.7 μm, the basis weight of the nonwoven fabric was 16 g / m ² , and the flat fiber diameter was 4 μm. The film portion of the base paper was carefully peeled off to separate only the porous support, and the pressure loss of air in the porous support was measured.
Met.

Table 1 shows the results of evaluation of printability using this base paper. The first printed matter printed using this base paper was unclear. Example 3 A heat-sensitive stencil sheet was prepared in the same manner as in Example 1 except that the fiber diameter of the unstretched nonwoven fabric was 6 μm.

The thickness of the obtained base paper was 45 μm, the film thickness was 1.7 μm, the basis weight of the nonwoven fabric was 10 g / m ² , and the fiber diameter was 3 μm. The film portion of the base paper was carefully peeled off to separate only the porous support, and the pressure loss of air of the porous support was measured.
Met.

Table 1 shows the results of evaluation of printability using this base paper. The first printed matter printed using this base paper was clear. Comparative Example 2 A heat-sensitive stencil sheet was prepared in the same manner as in Example 1 except that the fiber diameter of the unstretched nonwoven fabric was changed to 4 μm.

The thickness of the obtained base paper was 40 μm, the film thickness was 1.7 μm, the basis weight of the nonwoven fabric was 10 g / m ² , and the fiber diameter was 2 μm. The film portion of the base paper was carefully peeled off to separate only the porous support, and the pressure loss of air in the porous support was measured.
Met.

Table 1 shows the results of evaluation of printability using this base paper. The first printed matter printed using this base paper was unclear. Example 4 A heat-sensitive stencil sheet was prepared in the same manner as in Example 1 except that the nip roll linear pressure was changed to 10 N / cm.

The thickness of the obtained base paper was 40 μm, the film thickness was 1.7 μm, the basis weight of the nonwoven fabric was 10 g / m ² , and the average fiber diameter was 4 μm. The film portion of the base paper was carefully peeled off to separate only the porous support, and the pressure loss of air in the porous support was measured.
Aq.

Table 1 shows the results of evaluation of printability using this base paper. The first printed matter printed using this base paper was clear. Comparative Example 3 A heat-sensitive stencil sheet was prepared in the same manner as in Example 1, except that the nip roll linear pressure was changed to 50 N / cm. The thickness of the obtained base paper was 30 μm, the film thickness was 1.7 μm, the basis weight of the nonwoven fabric was 10 g / m ² , and the fiber diameter was 4 μm. The film portion of the base paper was carefully peeled off to separate only the porous support, and the pressure loss of air of the porous support was measured.
Met. Table 1 shows the results of evaluation of printability using this base paper. The first printed matter printed using this base paper was unclear. Example 5 Polyethylene terephthalate raw material (intrinsic viscosity 0.70,
(Melting point: 255 ° C.) by a spun bond method and a fiber diameter of 6
A nonwoven fabric having a thickness of 50 μm, a basis weight of 12 g / m ² and a thickness of 50 μm was prepared. When measuring the pressure loss of air of the nonwoven fabric,
It was 1.2 mmAq.

The nonwoven fabric and a 1.7 μm-thick polyester film were adhered with a vinyl acetate-based adhesive, and a silicone-based adhesive was applied to the film surface to prepare a heat-sensitive stencil sheet.

Table 1 shows the results of evaluation of printability using this base paper. The first printed matter printed using this base paper was clear. Example 6 A heat-sensitive stencil sheet was prepared in the same manner as in Example 5 except that the nonwoven fabric after spinning was calendered to a thickness of 40 μm. The pressure loss of air of the produced nonwoven fabric was 3.3 mmAq.

Table 1 shows the results of evaluation of printability using this base paper. The first printed matter printed using this base paper was clear. Comparative Example 4 A heat-sensitive stencil sheet was prepared in the same manner as in Example 1, except that the nonwoven fabric after spinning was calendered to a thickness of 30 μm. The pressure loss of air of the produced nonwoven fabric was 5.4 mmAq.

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

[0051]

[Table 1]

In Examples 1 to 6, a porous support having a pressure loss of the internal air of less than 5.0 mmAq is used. A printed matter was obtained. On the other hand, in Comparative Examples 1, 2, 3, and 4 using a porous support having a pressure loss of the internal air of 5.0 mmAq or more, the printing was unclear.

[0053]

According to the present invention, it is possible to provide an excellent heat-sensitive stencil sheet capable of obtaining a high-quality printed matter from the first sheet even when printing on a high-resolution model.

Claims (2)

[Claims] 1. A heat-sensitive stencil printing paper comprising a thermoplastic resin film and a porous support, wherein the pressure loss of air inside the porous support is less than 5 mmAq. Base paper. 2. The heat-sensitive stencil printing paper according to claim 1, wherein said porous support is made of polyester fiber.