JP2000203173A - Heat sensitive stencil printing paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a high image quality printing and, at the same time, improve the conveyability of a stock paper by a method wherein a thin metal film layer is provided on the fibers of a porous support in a heat sensitive stencil printing paper consisting of a thermoplastic resin film and the porous support. SOLUTION: A heat sensitive stencil printing paper, which is boringly processed with a thermal head, laser beams or the like, is formed by providing a thermoplastic resin film and a porous support. In this case, in order to obtain a stock paper, which has a higher picture quality and develops no transposing fault and the conveyability of which is excellent, a thin metal film layer is formed over the fibers of the porous support comprising the stock paper. As the metal to be formed aluminum, nickel, zinc, tin or the like in a single form or their mixture and their oxide are employed. In addition, as the fibers comprizing the porous support, natural fibers, synthetic fibers, inorganic fibers or other fibers are employed and preferably polyester fibers are empolyed. As the thermoplastic resin film, polyester, its copolymer or their blend is suitable.

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 perforated by a thermal head, a laser beam or the like, and more particularly to a heat-sensitive stencil sheet having good image quality and excellent transportability. .

[0002]

2. Description of the Related Art Conventionally, as heat-sensitive stencil base paper,
There is known a structure in which a thermoplastic resin film such as polyester and a porous support made of natural fibers or synthetic fibers are adhered with an adhesive (for example, Japanese Patent Application Laid-Open No.
182495, JP-A-58-147396, JP-A-59-2896, etc.).

In recent years, in order to increase the resolution of a heat-sensitive stencil printing machine, the thermal element density of a thermal head has been reduced to a conventional 400 dp.
It is desired to increase the density from i to 600 dpi.

However, in the case of printing at a high resolution using the conventional heat-sensitive stencil printing paper, the resolution is improved, but the white spot defect in the solid black portion is conspicuous, and the image quality as a whole image is not necessarily good. It turned out that there was a problem of not becoming.

[0005] The reason is that when the dot density of the thermal head is increased from 400 dpi to 600 dpi, the perforated area per thermal element (1 dot) of the thermal head becomes smaller, and the fibers and binders constituting the porous support material reduce the perforated area. This is because the perforated portion of the film is likely to be closed, and the passage of ink is hindered. In addition, the perforation energy of the thermal head is 60 from 400 dpi.
Since 0 dpi is lower, one of the causes is that unperforated film is easily generated. In order to solve this drawback, the film is made thinner to increase the sensitivity, the fibers constituting the porous support are made as thin as possible, the binding of the fibers is eliminated, and the basis weight of the support fibers is made as low as possible. It is effective to reduce the amount of adhesive used. However, when the film is made thinner, the fibers constituting the porous support are made thinner, and the basis weight is reduced, the white spot defect is improved, but the transportability of the base paper is reduced, and the time required for plate making is reduced. It has been found that there is a new problem that wrinkles are likely to be generated on the plate making master during plate making, and the wrinkles are transferred to printing paper.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the conventional heat-sensitive stencil printing paper and to provide a heat-sensitive stencil printing paper having high image quality and excellent transportability. I do.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies on the porous support of heat-sensitive stencil printing paper in order to solve the above-mentioned problems. As a result, a thin metal layer was formed on the fibers of the porous support. By doing so, it has been found that the drawbacks of the conventional base paper can be improved, and the present invention has been completed.

That is, the present invention relates to a heat-sensitive stencil printing paper comprising a thermoplastic resin film and a porous support, wherein the fibers of the porous support have a metal thin film layer. It is a base paper.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention has been extensively studied in order to provide a heat-sensitive stencil printing paper having high image quality, no white spot defect, and excellent transportability of the base paper. By forming a thin film layer of metal on body fibers,
It has been found that such a problem can be solved.

That is, it is important that the porous support of the present invention has a metal thin film layer formed on the surface of the constituting fiber. Gold, silver,
Aluminum, palladium, nickel, cobalt, zinc, tin, titanium, indium, and the like may be used alone or in combination, or an oxide thereof. Particularly preferably, aluminum, nickel, zinc, tin, etc., alone or in combination, and oxides thereof are used.

The metal thin film layer does not necessarily need to be formed on the entire surface of the fiber constituting the porous support.
Preferably at least 10% of the fiber surface, more preferably 3%
What is necessary is just to be formed in 0% or more. The thickness of the metal film is not particularly limited, but is preferably at least 100 Å to 1000 Å.

In the present invention, the fibers in the porous support are not necessarily required to have a metal thin film layer. 10% or more fiber by ratio, more preferably 30%
% Or more of the fibers preferably has the thin film layer.

The reason why the transportability is improved by forming a thin film layer of metal on the fibers of the porous support is to reduce the slip resistance between the transport roll and the porous support or to reduce the ink on the plate cylinder. It is presumed to be due to a change in the affinity between the polymer and the porous support.

The fibers constituting the porous support of the present invention are:
There is no particular limitation as long as it has an ink passage property, and natural fibers, synthetic fibers, inorganic fibers, and other fibers can be used. Further, a mixture of these fibers may be used. Preferred are thermoplastic resin fibers such as polyamide, polypropylene, polyethylene, polyester and polyphenylene sulfide, whose fiber diameter can be arbitrarily selected. Among them, polyester fibers are particularly preferred in view of the strength of the support.

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 fiber constituting the porous support of the present invention is preferably 0.5 to 20 μm, more preferably 0.5 to 15 μm, and particularly preferably 0.5 to 10 μm.
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 an arbitrary cross-sectional shape can be used.

In the present invention, the basis weight of the porous support is preferably from 1 to ²⁰ g / m ² , more preferably from 1 to 15 g / m ² , particularly preferably from 1 to 10 g / m ² from the viewpoint of ink retention. 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 and the like. Organic lubricant or an antifoaming agent such as polysiloxane. Further, in order to impart an affinity with the metal film, the surface of the fiber may be subjected to a chemical treatment such as an acid or an alkali, a corona treatment, a low-temperature plasma treatment or the like, if necessary.

As the thermoplastic resin film in the present invention, polyester, polyamide, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, respective copolymers, blends thereof and the like are used. And a copolymer or blend thereof. The polyester is a polyester containing an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid or an alicyclic dicarboxylic acid and a diol as main components.

The aromatic dicarboxylic acid component includes, 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.

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.

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.
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-
Cyclohexanedimethanol, 1.3-cyclohexanedimethanol, 1.4-cyclohexanedimethanol,
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. One of these diol components may be used alone,
More than one species may be used in combination.

The polyester used for 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. Copolymer with terephthalate, copolymer of butylene terephthalate and hexamethylene terephthalate, hexamethylene terephthalate and 1,4-
Copolymers with 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, but examples thereof include inorganic particles such as clay, mica, titanium oxide, calcium carbonate, kaolin, talc, wet or dry silica, alumina and zirconia.
There are a method of blending organic particles containing acrylic acid, styrene or the like as a constituent, a method of so-called internal particles for precipitating a catalyst or the like to be added at the time of a polyester polymerization reaction, and the like.

The thermoplastic resin film of the present invention comprises:
Those stretched in at least one axial direction are preferred.
More preferably, it is a biaxially stretched film. The stretching ratio is not particularly limited, but is preferably 2 times or more 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 melting point of the thermoplastic resin film in the present invention is preferably 230 ° C. or lower, more preferably 220 ° C.
° C or lower, particularly preferably 210 ° C or lower. When there are two or more peaks of the melting point as measured by the differential scanning calorimeter, at least one peak temperature is 230 ° C.
It is preferred that: The lower limit of the melting point of the thermoplastic resin film is preferably 130 ° C. or more from the viewpoint of film forming stability.

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

The thermoplastic resin film of the present invention and the porous support may be bonded using an adhesive or may be bonded without using an adhesive. As a method of bonding without using an adhesive, the film and the porous support may be simply thermally bonded, or the undrawn thermoplastic resin film and the undrawn thermoplastic resin fiber are thermally bonded at a low temperature. rear,
A method in which both are simultaneously stretched and integrated may be adopted. In this case, the unstretched thermoplastic resin film and the unstretched thermoplastic resin fiber have substantially non-oriented molecules,
It is preferable that the crystallinity is as low as possible. Such an unstretched thermoplastic resin film can be produced, for example, by quenching a polymer on a cast drum by a T-die extrusion method, and an unstretched thermoplastic resin fiber can be formed directly by a melt blow method or the like. In the melt spinning method, it can be produced by controlling spinning conditions.

The method for forming the metal thin film layer on the fibers of the porous support is not particularly limited, but a vacuum evaporation method is preferred. The formation of the metal film may be performed by vacuum deposition after bonding the film and the porous support, or may be performed after forming the metal film on the porous support in advance.

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.

[0036]

[Measurement method of characteristics] (1) Fiber diameter (μm) Photographs at a magnification of 2000 times were taken with an electron microscope at arbitrary 10 places on the support side of the base paper, and 1 photograph was taken for each photograph.
Five fiber diameters were measured for a total of 150 fibers, and the average value was determined.

(2) Basis weight (g / m ² ) The film was peeled from the base paper, cut into a size of 20 cm × 20 cm, weighed, and converted to the weight per m ² .

(3) 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.

(4) Conveyability The prepared base paper was supplied to a printing machine “RISOGRAPH” GR377 manufactured by Riso Kagaku Kogyo Co., Ltd. An 8 chart (manufactured by Riso Kagaku Kogyo Co., Ltd.) was used as a manuscript to make a plate, and the plate was subjected to plate making, and the presence or absence of wrinkles was observed. This operation was performed 50 times, and the following judgment was made.

[0040] The wrinkles that did not occur at all 50 times were
“O”: Wrinkles occurred once in 50 times, “Δ”: Wrinkles occurred twice or more in 50 times, “X”. "△" and above are practical levels.

(5) Image Properties The produced base paper is supplied to a printing machine “Risograph” GR377 manufactured by Riso Kagaku Kogyo Co., Ltd. Printed sheets. With respect to the 100th image, the white spot defect in the solid black portion was visually observed and determined as follows.

When no white spot defect was generated, “◎”: less than 5 white spot defects, “○”: 5 to 10 white spot defects, “△”: white spot defect The ones having more than 10 were designated as "x". "△" and above are practical levels.

[0043]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

Example 1 Polyethylene terephthalate raw material ([η] = 0.50,
Tm = 255 ° C.) by a melt blow method to produce an unstretched nonwoven fabric having a fiber diameter of 7.8 μm and a basis weight of 100 g / m ² .

Then, a copolyester resin raw material ([η] = 0.65, Tm = 220 ° C.) composed of ethylene terephthalate and ethylene isophthalate was extruded with a T-die die, cast on a cooling drum having a diameter of 500 mm, and uncoated. A stretched film was produced.

The unstretched film and the unstretched nonwoven fabric were stacked and supplied to a roll-type stretching machine, stretched 4.0 times in the longitudinal direction at a roll temperature of 95 ° C., and cooled to room temperature. Next, the film is fed into a tenter type horizontal stretching machine, stretched 3.5 times in the width direction at a temperature of 95 ° C., and further subjected to a heat treatment for 5 seconds in an atmosphere of 140 ° C., a film thickness of 1.5 μm and a fiber diameter of the support of 4 μm. And a composite sheet having a basis weight of 7.2 g / m ² .
Aluminum metal was deposited to a thickness of 400 to 500 angstroms on the support fiber side of the composite sheet using an electron beam heating type vacuum evaporator. Thereafter, a water-soluble release agent was applied to the film surface to prepare a heat-sensitive stencil printing base paper of the present invention. Table 1 shows the results of a printing test performed using the base paper.

Comparative Example 1 A heat-sensitive stencil sheet was prepared in the same manner as in Example 1 except that aluminum metal was not deposited. Table 1 shows the results of a printing test performed using the base paper.

Example 2 Only the unstretched nonwoven fabric sheet prepared in Example 1 was supplied to a roll-type stretching machine, and rolled at a roll temperature of 95 ° C. in the longitudinal direction.
The film was stretched 0 times and cooled to room temperature. Next, it is sent to a tenter type horizontal stretching machine, stretched 3.5 times in the width direction at a temperature of 95 ° C., and further subjected to a heat treatment for 5 seconds in an atmosphere of 180 ° C. to obtain a fiber diameter of 4.2 μm and a basis weight of 7.4 g / m. ^Two porous supports were prepared. Using an electron beam heating type vacuum evaporator on the porous support, aluminum metal was 400 to 500
Angstrom thickness was deposited.

On the other hand, a biaxially stretched polyester film having a thickness of 1.5 μm was produced using the same copolymerized polyester raw material as in Example 1 under the same conditions as in Example 1. The film and the vapor-deposited porous support were adhered with a vinyl acetate-based adhesive, and a water-soluble release agent was applied to the film surface to prepare a heat-sensitive stencil sheet. Table 1 shows the results of a printing test performed using the base paper.

Comparative Example 2 A heat-sensitive stencil sheet was prepared in the same manner as in Example 2, except that aluminum metal was not deposited on the porous support. Table 1 shows the results of a printing test performed using the base paper.

[0051]

[Table 1] As is clear from Table 1, Examples 1 and 2 formed a thin film layer of aluminum metal on the fibers of the porous support.
Those printed with the base paper have good image properties and excellent transportability. On the other hand, Comparative Examples 1 and 2 are inferior in transportability because a thin film layer of aluminum metal is not formed on the fibers of the porous support.

[0052]

According to the heat-sensitive stencil printing paper of the present invention, the fibers of the porous support have a thin film layer of metal. Since the base paper is excellent in transportability, even when a large number of sheets are printed, the base paper does not wrinkle and the image quality does not deteriorate.

Claims (3)

[Claims] 1. A heat-sensitive stencil sheet comprising a thermoplastic resin film and a porous support, wherein the fibers of the porous support have a thin film layer of metal. 2. The heat-sensitive stencil printing paper according to claim 1, wherein the porous support comprises polyester fibers. 3. The heat-sensitive stencil printing paper according to claim 1, wherein the thermoplastic resin film is a polyester film.