JPH0867081A - Thermosensitive stencil printing sheet - Google Patents

Abstract

PURPOSE: To obtain a thermosensitive stencil printing sheet with high perforation sensitivity and outstanding image sharpness. CONSTITUTION: A thermosensitive stencil printing sheet has thermoplastic resin film laminated on one surface of a porous support. The maximum surface roughness(Rt) of the thermoplastic resin film in a laminated state is less than 10μm and the smoothness measured by Open-type smoothness tester is, at least.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a heat-sensitive stencil printing base paper. More specifically, it relates to a heat-sensitive stencil printing base paper which is perforated by a thermal head or the like.

[0002]

2. Description of the Related Art Thermal stencil printing has been known as a simple printing method replacing conventional copying machines. In heat-sensitive stencil printing, an ink-permeable porous support laminated with a thermoplastic resin film is used as the base paper, and the image of the document read by the sensor is sent to the thermal head as a signal, and the heat generated by the thermal head causes the thermoplastic resin to flow. The film is heated and melted for perforation plate-making, printing ink is leached from the side of the porous support into the perforated portion, and printing is performed on printing paper.

Conventionally, as a base paper for heat-sensitive stencil, a porous support composed of a thermoplastic resin film such as a polyester film, a vinylidene chloride film or a polypropylene film, a thin paper made of natural fibers or synthetic fibers, a nonwoven fabric, a screen gauze, etc. A structure in which the body and the body are attached with an adhesive is known (Japanese Patent Laid-Open No. 57-182).
495, JP-A-58-147396, JP-A-59-15898, etc.).

However, these conventional heat-sensitive stencil sheets are not always satisfactory in terms of the clarity of the printed image. There are various possible reasons for insufficient image clarity, one of which is due to the perforability of the thermoplastic resin film. In order to improve the perforation sensitivity of the thermoplastic resin film, it is effective to reduce the thickness of the film to lower the perforation energy, but if the thickness of the film is reduced, the fibers constituting the porous support will be As a result, irregularities appear on the surface of the base paper, the contact with the thermal head becomes insufficient, the perforation of the film is incomplete, and as a result, high quality printed matter cannot be obtained.

In order to remedy these drawbacks, it has been proposed to use thin paper in which natural fibers are mixed with finer synthetic fibers. (JP-A-60-217197, JP-A-63-59394, etc.). Further, a method has been proposed in which, when the support and the film are bonded together with an adhesive, the film surface is moved while being brought into close contact with a mirror surface roll to smooth the film surface (Japanese Patent Laid-Open No. Sho 60).
-89396). Although some improvements were seen, they were not complete.

[0006]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned drawbacks and to provide a heat-sensitive stencil sheet having excellent perforation sensitivity and capable of high-quality printing.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the inventors of the present invention have conducted diligent research focusing on a perforation mechanism of a heat-sensitive stencil sheet (hereinafter referred to as a sheet). The inventors have found that the defects of the conventional base paper can be improved by specifying the smoothness, and have completed the present invention.

That is, the present invention relates to a heat-sensitive stencil sheet comprising a porous support and a thermoplastic resin film laminated on one surface thereof, wherein the thermoplastic resin film surface has a maximum surface roughness (Rt). ) Is 10 μm or less, and the Oken type smoothness is 1000 seconds or more, which is a heat-sensitive stencil base paper.

The thermoplastic resin film in the present invention is
For example, conventionally known materials such as polyester, polyamide, polypropylene, polyethylene, polyvinyl chloride, polyvinylidene chloride or copolymers thereof are used, and polyester film is particularly preferably used from the viewpoint of perforation sensitivity.

The polyester used in the polyester film is preferably polyethylene terephthalate, a copolymer of ethylene terephthalate and ethylene isophthalate, a copolymer of hexamethylene terephthalate and cyclohexane dimethylene terephthalate, and the like. Particularly preferred for improving the perforation sensitivity are a copolymer of ethylene terephthalate and ethylene isophthalate, a copolymer of hexamethylene terephthalate and cyclohexane dimethylene terephthalate, and the like.

The thermoplastic resin film in the present invention is
Usually, it is preferably stretched, and can be produced by a conventionally known T-die method, inflation method, or the like. For example, in the T-die method, an unstretched film can be produced by extruding a polymer on a cast drum, then longitudinally stretched by a heating roll group, and if necessary, supplied to a tenter or the like for lateral stretching. The thickness of the unstretched film can be adjusted by adjusting the slit width of the die, the discharge amount of the polymer, and the rotation speed of the cast drum.Also, the rotation speed of the heating roll group and the setting of the tenter can be adjusted. By changing the width, it is possible to stretch at a desired stretching ratio.

In the thermoplastic resin film of the present invention, 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, a wax, or a polysulfate. An antifoaming agent such as siloxane can be blended.

Further, slipperiness can be imparted if necessary. The method for imparting slipperiness is not particularly limited, but examples thereof include clay, mica, titanium oxide, calcium carbonate, kaolin, talc, inorganic particles such as wet or dry silica, organic particles containing acrylic acid, styrene and the like as constituent components. And the like, a method using internal particles, a method of applying a surfactant, and the like.

The thickness of the thermoplastic resin film in the present invention is usually preferably 0.1 to 10 μm, more preferably 0.1 to 5.0 μm, and more preferably 0.1.
Is about 3.0 μm. If the thickness exceeds 10 μm, the piercing property may decrease, and if it is less than 0.1 μm, the film forming stability may deteriorate.

The porous support in the present invention is not particularly limited as long as it is permeable to printing ink, and thin paper, papermaking paper, non-woven fabric, woven fabric, screen gauze, etc. can be used. In the present invention, a non-woven fabric made of synthetic fiber is more preferably used.

The non-woven fabric can be produced by a conventionally known direct melt spinning method such as a flash spinning method, a melt blow spinning method and a spun bond spinning method. In the present invention, the melt blow spinning method and the spun bond spinning method are more preferably used. . For example, in the melt blow spinning method, when the molten polymer is discharged from the spinneret, hot air is blown from the periphery of the spinneret, the discharged polymer is made finer in fineness, and then sprayed on a net conveyor arranged at an appropriate position. It is manufactured by collecting and collecting a web to form a web.

Similarly, in the spunbond method, the polymer discharged from the die is pulled by an air ejector, and the obtained filament is collided with a collision plate to open the fiber,
It is manufactured by collecting it on a conveyor to form a web.

In the porous support of the present invention, the surface of the fiber constituting the ink is optionally subjected to chemical treatment with acid, alkali or the like, corona treatment, low-temperature plasma treatment, etc. in order to impart affinity with the ink. Good.

As the synthetic fiber in the present invention, conventionally known ones such as polyester, polyamide, polyphenylene sulfide, polyacrylonitrile, polypropylene, polyethylene or a copolymer thereof can be used. Polyester is particularly preferably used. Preferable examples of the polyester include polyethylene terephthalate, polyethylene naphthalate, polycyclohexane dimethylene terephthalate, and a copolymer of ethylene terephthalate and ethylene isophthalate. From the viewpoint of thermal dimensional stability during perforation, polyethylene terephthalate and polyethylene naphthalate are particularly preferable. These polymers may include flame retardants, heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, pigments, if necessary.
Organic lubricants such as dyes, fatty acid esters and waxes, defoaming agents such as polysiloxanes and the like can be added.

The polyester used in the synthetic fiber and the thermoplastic resin film of the present invention is a polyester having an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid or an aliphatic dicarboxylic acid and a diol as main constituent components. Here, as the aromatic dicarboxylic acid, 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'-diphenyl sulfone dicarboxylic acid and the like can be mentioned. Examples of the aliphatic dicarboxylic acid component include adipic acid, suberic acid, sebacic acid, dodecanedioic acid and the like. Of these, terephthalic acid and isophthalic acid are preferred. These acid components may be used alone or in combination of two or more, and further, an oxy acid such as hydroxybenzoic acid may be partially copolymerized. Examples of the diol component include 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-
Examples thereof include cyclohexanedimethanol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, and 2,2'bis (4'-β-hydroxyethoxyphenyl) propane. Among them, ethylene glycol is preferably used. These diol components may be used alone or in combination of two or more.

The polyester in the present invention can be produced by a conventionally known method. For example, a method in which an acid component is directly esterified with a diol component and then the product of this reaction is heated under reduced pressure to polycondense while removing the excess diol component, or a dialkyl as the acid component There is a method in which an ester is used, an ester exchange reaction is carried out between the ester and a diol component, and then polycondensation is carried out in the same manner as described above. At this time, if necessary, a conventionally known alkali metal, alkaline earth metal, manganese, cobalt, zinc, antimony as a reaction catalyst,
Germanium, a titanium compound, etc. can also be used.

In the porous support of the present invention, the area fraction of the openings formed by the support is preferably 5 to 80%, more preferably 5 to 50% when the support is observed in a plane. , And more preferably 5 to 30%. If the open area fraction is less than 5%, the ink permeability is poor, and the printed image becomes faint and the sharpness deteriorates. If it exceeds 80%, the ink holding property is lowered, so that the printed image becomes bleeding and the show-through easily occurs. The open area ratio in the present invention is a percentage of the area occupied by the open area when a certain area of the support is observed in a plane.

The porous support according to the present invention preferably has a mesh-like structure in which fibers are irregularly fused to each other at the entanglement points. Particularly preferably, a thin film-like fold is formed in a part of the fusion-bonded portion. That is, the fibers of the support can be formed into a mesh-like body having a fused portion formed by forming a thin film fold, so that the strength of the support can be stabilized and a uniform opening shape can be formed. It is possible to obtain a base paper having a good balance between printing ink retention and transparency.

The basis weight of the porous support in the present invention is
Usually preferably ^{2 to 20} g / m ² , more preferably 5
Is about 15 g / m ² . If the weight per unit area exceeds 20 g / m ² , the ink permeability decreases and the image clarity decreases.
If the basis weight is less than 2 g / m ² , sufficient strength as a support cannot be obtained.

The base paper in the present invention is made by laminating and integrating the above thermoplastic resin film and a porous support made of synthetic fiber. Lamination may be performed by using an adhesive under conditions that do not reduce the perforation sensitivity of the film, or the film and the support may be heat-adhered without using an adhesive, but from the viewpoint of surface smoothness. It is preferable that the thermoplastic resin film and the porous support are directly fixed to each other by thermal bonding without using an adhesive.

Thermal bonding is usually carried out by thermocompression bonding in which the thermoplastic resin film and the porous support are directly bonded while heating. The method of thermocompression bonding is not particularly limited, but thermocompression bonding with a heating roll is particularly preferable from the viewpoint of processability.

As a preferred embodiment of the present invention, it is particularly preferred that the unstretched thermoplastic resin film and the porous support having a low orientation degree are co-stretched in a thermocompression bonded state. By co-drawing both, the fiber diameter is reduced and
The cross-sectional shape of the fiber is deformed from a circular shape to an elliptical shape or a semicircular shape on the surface fixed to the film. Therefore, the unevenness of the fibers does not appear on the surface of the base paper, and the surface roughness can be small and the smoothness can be excellent. At this time, the fibers of the support are stretched in a state where they are fused to each other at the entanglement point, so that it is possible to form a reticulated body suitable as a support, and by co-stretching the both together, heat The plastic resin film and the porous support are preferably directly fixed to each other.

The method of co-stretching is not particularly limited, but biaxial stretching is particularly preferred in the present invention. The biaxial stretching may be either sequential biaxial stretching or simultaneous biaxial stretching. In the case of sequential biaxial stretching, it is general to stretch in the longitudinal direction and then in the transverse direction, but the stretching may be reversed. The draw ratio is not particularly limited and is appropriately determined depending on the type of the thermoplastic resin used, but usually about 2 to 7 times in both the length and width are suitable. Further, after biaxial stretching, it may be re-stretched longitudinally or laterally or simultaneously in longitudinal and lateral directions.

Further, in the present invention, it is preferable to heat-treat the base paper after biaxial stretching. This is because the smoothness of the surface of the raw paper is further improved by heat-treating the support and the film integrally. The heat treatment temperature is not particularly limited and is appropriately determined depending on the kind of the thermoplastic resin used, but in the case of the polyester resin, it is 100 to 24.
It is preferably carried out in the range of 0 ° C.

The base paper of the present invention has a maximum surface roughness (Rt) of 10 μm on the surface of the laminated thermoplastic resin film.
m or less, preferably 8 μm or less, more preferably 6 μm or less, and further preferably 5 μm or less. Rt
Is more than 10 μm, the contact with the thermal head becomes extremely poor and the perforation property deteriorates.

The base paper of the present invention has a Oken type smoothness of 1000 seconds or more, preferably 2000 seconds or more, and more preferably 3000 seconds or more on the surface of the laminated thermoplastic resin film. When the smoothness is less than 1000 seconds, the contact with the thermal head becomes extremely poor, and the piercing property deteriorates.

The peel strength between the thermoplastic resin film constituting the base paper of the present invention and the porous support is preferably 1 g / 25.
mm or more, more preferably 3 g / 25 mm or more, and further preferably 5 g / 25 mm or more. Peel strength is 1g
If it is smaller than / 25 mm, the perforated shape of the thermoplastic resin film tends to be non-uniform.

A release agent is preferably applied to the film surface of the base paper of the present invention to prevent sticking during perforation. As the release agent, a conventionally known release agent such as silicone oil, silicone resin, fluorine resin, and surfactant can be used.

Further, various additives such as an antistatic agent, a heat-resistant agent, an antioxidant, an organic particle, an inorganic particle and a pigment can be mixed and used in the release agent.

[0035]

[Characteristics measurement method]

(1) Maximum surface roughness (μm) Based on JISB-0601, the maximum surface roughness (Rt) in the MD and TD directions was measured with a roughness measuring machine SE-3E manufactured by Kosaka Seisakusho.
Was measured at each of 5 points, and the average value was calculated.

(2) Oken-type smoothness (second) Five samples of 15 cm × 15 cm were prepared and the smoothness was measured using Asahi Seiko KK-made smoothness tester type KB15. The average value was calculated.

(3) Perforation rate (%) The prepared base paper is "Lisograph" R manufactured by Ideal Science Co., Ltd.
It is supplied to A205, and a plate with a side of 10 mm is prepared by a thermal head type plate making method, and the plate making part is observed with a scanning electron microscope at a magnification of 100 times.
The number of unpierced holes corresponding to 25 dots was counted, and the perforation rate was calculated from the following equation.

Perforation rate = [(225-number of unperforated holes) / 225] × 100

(4) Evaluation of printability The prepared base paper is "Lisograph" R manufactured by Ideal Science Industry Co., Ltd.
It was supplied to A205, and a thermal head type plate making method was used to make a plate having a character size of 6 to 10.5 and a (circle filled in black) of 0.5 to 15 mmφ as an original. . By visually deciding what was printed using a plate-making manuscript, the letters are clear and there are no white spots on the solid black areas, and the letters are unclear and the black solid portions are marked with white areas. It was evaluated as Δ when it was in the middle of the above range and was practically manageable.

[0040]

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

Examples 1 to 3 A polyethylene terephthalate raw material ([η] = 0.61, Tm = 265 ° C.) was melt-blown at a die temperature of 300 ° C. using a rectangular die having a hole diameter of 0.3 mm and 75 holes. By spinning method, average fiber diameter 8μm, 10μm, 12μ
A non-woven fabric having a m and a basis weight of 100 g / m ² was prepared. The crystallinity of the nonwoven fabric was 5%.

Then, polyethylene terephthalate 86
Copolyester resin raw material ([η] = 0.67, T
(m = 226 ° C.) was extruded at a T-die die temperature of 280 ° C. using an extruder having a screw diameter of 40 mm and cast on a cooling drum to prepare an unstretched film.

The above-mentioned non-woven fabric was laid on the unstretched film, supplied to a heating roll and thermocompression-bonded at a roll temperature of 80 ° C. to prepare a laminated sheet.

The laminated sheet was placed between heating rolls at 90 ° C.
After stretching 3.5 times in the length direction, it was fed into a tenter type stretching machine, stretched 4 times in the width direction at 95 ° C, and further heat-treated at 165 ° C inside the tenter. On the film surface, at the inlet of the tenter, a wax release agent was applied by a gravure coater to a dry weight of 0.1 g / m ² to prepare heat-sensitive stencil base papers of Examples 1 to 3. . The film thickness of the base paper was 1.2 μm.

Examples 4 and 5 A polyethylene terephthalate raw material ([η] =) was used at a die temperature of 280 ° C. using a die having a hole diameter of 0.3 mm and 70 holes.
(0.64, Tm = 265 ° C.) is spun and dispersed and collected on a conveyor by an air ejector at a spinning speed of 1200 and 1400 m / min to prepare a nonwoven fabric having an average fiber diameter of 15 μm, 18 μm and a basis weight of 60 g / m ^2. did. The crystallinity of the nonwoven fabric was 8%.

Then, polyethylene terephthalate 80
Copolyester resin raw material ([η] = 0.67, T
m = 205 ° C) is extruded at a T-die die temperature of 270 ° C using an extruder with a screw diameter of 40 mm, and the diameter is 300 mm.
An unstretched film was produced by casting on a cooling drum of

The above nonwoven fabric was laid on the unstretched film, supplied to a heating roll and thermocompression bonded at a roll temperature of 90 ° C. to prepare a laminated sheet.

The laminated sheet was stretched 3 times in the length direction with a heating roll at 90 ° C. and then fed into a tenter type stretching machine,
It was stretched 3.3 times in the width direction at 90 ° C. Further, it was heat-treated at 165 ° C. inside the tenter. Further, at the inlet of the tenter, a wax-based release agent was applied to the film surface with a gravure coater at a dry weight of 0.1 g / m ² to obtain heat-sensitive stencil base papers of Examples 4 and 5. The film thickness of the base paper was 1.8 μm.

Comparative Example 1 A nonwoven fabric having an average fiber diameter of 12 μm and a basis weight of 12 g / m ² was prepared by changing the collection speed under the same raw materials and spinning conditions as in Example 1. The non-woven fabric and the thickness produced in Example 1: 1.
A 2 μm polyester film was laminated using a vinyl acetate resin, and a wax-based release agent was applied to the film surface to prepare a heat-sensitive stencil sheet.

Comparative Example 2 The same raw material as in Example 4 was used, and the spinning speed was 1200.
m / min, the collection speed was changed to obtain an average fiber diameter of 15 μm,
A nonwoven fabric having a basis weight of 13.5 g / m ² was produced. The nonwoven fabric and the 1.8 μm-thick polyester film prepared in Example 4 were bonded together using a vinyl acetate resin, and a wax-based release agent was applied to the film surface to prepare a heat-sensitive stencil sheet.

Comparative Example 3 A polyethylene terephthalate raw material ([η] =) was used at a die temperature of 290 ° C. using a die having a hole diameter of 0.3 mm and 70 holes.
(0.65, Tm = 257 ° C.) is spun out, dispersed and collected on a conveyor by an air ejector at a spinning speed of 4500 m / min, and then wound by being pressed by an embossing roll at 220 ° C. and having an average fiber diameter of 17 μm. A non-woven fabric having a basis weight of 16 g / m ² was produced.

Next, the 1.8 μm-thick polyester film prepared in Example 4 was laminated on the non-woven fabric using a vinyl acetate resin, and a wax release agent was applied to the film surface to prepare a heat-sensitive stencil sheet. did.

Comparative Example 4 A thin paper having a basis weight of 10.5 g / m ² made from Manila hemp and the 1.2 μm-thick polyester film prepared in Example 1 were bonded together using a vinyl acetate resin, and the film surface was adhered. A wax release agent was applied to prepare a heat-sensitive stencil sheet.

[0054]

[Table 1] As can be seen from the results in Table 1, the maximum surface roughness is 10 μm.
Below, the heat-sensitive stencil sheet of the present invention having a surface smoothness of 1000 seconds or more is excellent in perforability and image sharpness.

[0055]

The base paper for heat-sensitive stencil of the present invention has the maximum surface roughness of 10 μm or less and the surface smoothness of 1000 seconds or more in the state where the porous support and the thermoplastic resin film are laminated. By doing so, it is possible to obtain a heat-sensitive stencil sheet having excellent perforation properties and capable of high-quality printing.

Claims (4)

[Claims] 1. A heat-sensitive stencil sheet comprising a thermoplastic resin film laminated on one surface of a porous support, wherein the thermoplastic resin film surface in the laminated state has a maximum surface roughness (Rt) of 10 μm or less, Oken type stencil sheet having a smoothness of 1000 seconds or more. 2. The heat-sensitive stencil sheet according to claim 1, wherein the porous support is mainly composed of synthetic fibers. 3. The base paper for heat-sensitive stencil according to claim 2, wherein the synthetic fiber is made of polyester resin. 4. The base paper for heat-sensitive stencil according to claim 1, wherein the thermoplastic resin film is a polyester resin film.