JPH0867082A - Thermosensitive stencil printing sheet - Google Patents

Abstract

PURPOSE: To obtain a thermosensitive stencil printing sheet with superb image sharpness and free from any running and crease-resistance problem. CONSTITUTION: This thermosensitive stencil printing sheet consists of thermoplastic resin film and a porous support composed mainly of synthetic fiber with an average fiber diameter of 2 to 15μm. The synthetic fiber has a fiber diameter distribution with a coefficient of variation of 5 to 50%.

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, the present invention relates to a heat-sensitive stencil sheet which is perforated by flash light irradiation with a halogen lamp or a xenon lamp, pulsed irradiation with a laser beam, or a thermal head.

[0002]

2. Description of the Related Art Conventional base papers used for heat-sensitive stencil printing include thermoplastic films such as polyester film, vinylidene chloride film, or polypropylene film, and thin paper, non-woven fabric, screen mainly composed of natural fibers or synthetic fibers. A structure having a structure in which a porous support made of gauze or the like is bonded with an adhesive is known (JP-A-57-182495, JP-A-58-58).
147396, JP-A-59-15898, etc.).

However, these conventional heat-sensitive stencil sheets have not always been satisfactory in terms of sharpness of printed images and printing durability. There are various possible reasons for insufficient image clarity, one of which is due to the fibers constituting the support. That is, since the thin paper made of natural fibers that has been used most often conventionally is thick and uneven, and is flat, the ink transmission tends to be uneven, and in particular, it exists in the perforated portion of the film. The fibers impede the ink transmission, and there are drawbacks such as faint printing and white spots in solid printing.

In order to improve these drawbacks, papermaking paper or non-woven fabric mainly made of synthetic fiber such as polyester fiber or polypropylene fiber is used in place of thin paper made of natural fiber to thin the fiber of the support or Have been proposed (JP-A-59-2896, JP-A-59-16793, JP-A-2-67197, etc.).

However, although the image clarity is improved by thinning the fibers of the support or reducing the basis weight, there is a problem that the strength and rigidity of the base paper are reduced. If the strength of the base paper is low, the running strength in the printing machine is insufficient, causing jams and tearing of the base paper. Further, when the rigidity is low, there is a drawback that wrinkles occur when the perforated base paper is wound around the printing drum, and the wrinkles deteriorate the printing quality.

In order to improve these drawbacks, it has been proposed to use thin paper made by combining two or more types of paper layers having different densities, or to make a multi-layer of fibers having different fineness. Has the problem that the manufacturing process becomes complicated and the cost becomes high, and the printing clarity and running stability are not completely satisfied at present (Japanese Patent Laid-Open No. 1-267094). Gazette, JP-A-3-193445, etc.).

[0007]

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 image clarity, running property and printing durability.

[0008]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the inventors of the present invention have conducted diligent research by paying attention to a running mechanism and a printing mechanism of a thermal stencil sheet (hereinafter referred to as a sheet) in a printing machine, and as a result, a support has been obtained. The inventors have found that the defects of the conventional base paper can be improved by specifying the fiber diameter and the distribution of the fibers, and have completed the present invention.

That is, the present invention is a heat-sensitive stencil sheet comprising a thermoplastic resin film and a porous support mainly composed of synthetic fibers having an average fiber diameter of 2 to 15 μm, which are laminated,
The heat-sensitive stencil base paper is characterized in that the fibers constituting the porous support have a fiber diameter distribution with a coefficient of variation of 5 to 50%.

A non-woven fabric is more preferably used as the porous support in the present invention.

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, but in the present invention, the melt blow spinning method and the spun bond method are more preferable.

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 to make the discharged polymer finer, and then on a net conveyor arranged at an appropriate position. It is manufactured by spraying, collecting, and forming 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 or the like in order to impart affinity with ink. Good.

In the porous support according to the present invention, when the support is observed two-dimensionally, the area fraction of the openings formed by the support is preferably 5 to 80%, more preferably 10 to 50%. Is. 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 the fibers are irregularly fused to each other at the entanglement points. Particularly preferably, a thin film fold is formed on a part of the fused portion. That is, the fibers of the support are a mesh-like body having a fused portion formed by forming a thin film fold, and the strength of the support is stable,
It is possible to form a uniform opening form, and it is possible to obtain a base paper in which the retention and the permeability of printing ink are well balanced.

The fiber basis weight of the porous support in the present invention is usually preferably ^{2 to 20} g / m ² , and more preferably 5 to 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 may not be obtained.

The average diameter of the synthetic fibers used for the porous support in the present invention is usually 2 to 15 μm, preferably 2-1.
The thickness is 2 μm, more preferably 2 to 10 μm, and further preferably 3 to 8 μm. If the average diameter is smaller than 2 μm,
The strength and heat resistance of the support are insufficient. Average diameter is 1
When it exceeds 5 μm, the thickness and basis weight of the support are likely to be non-uniform, and the ink transmission is likely to be non-uniform.

It is important that the synthetic fiber in the present invention has a fiber diameter distributed in a specific range. The range of the distribution is usually 5 to 50% of the coefficient of variation calculated by the following formula.
Is preferred, and more preferably 10-40%,
It is more preferably 10 to 30%.

Coefficient of variation = (standard deviation / average diameter) × 100 (%) If the coefficient of variation is less than 5%, the fiber diameter distribution becomes uniform,
When the average fiber diameter is small, strength and rigidity tend to be insufficient, and when the average fiber diameter is large, white spots are likely to occur during printing. When the coefficient of variation exceeds 50%, the distribution width of the fiber diameter becomes too large, and the printing performance and running performance required for the base paper cannot be satisfied at the same time. That is, in the base paper of the invention, fibers having different fiber diameters are randomly mixed in the entire support in a specific range to achieve both printing clarity and running stability.

As the synthetic fiber in the present invention, conventionally known fibers such as polyester, polyamide, polyphenylene sulfide, polyacrylonitrile, polypropylene, polyethylene or a copolymer thereof can be used. These synthetic fibers may be used alone, or may be used in combination of two or more kinds, and may also include natural fibers and regenerated fibers. From the viewpoint of thermal stability during perforation, polyester fiber 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.

In these polymers, if necessary, flame retardants, heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, pigments, dyes, fatty acid esters, organic lubricants such as waxes, or defoaming agents such as polysiloxanes. Agents and the like can be added.

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, or a copolymer of hexamethylene terephthalate and cyclohexane dimethylene terephthalate. 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 flame retardant, heat stabilizer, antioxidant, ultraviolet absorber, antistatic agent, pigment, dye, fatty acid ester, wax, or poly 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 polyester used in the synthetic fiber and the thermoplastic resin film of the present invention is a polyester mainly containing an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid or an aliphatic dicarboxylic acid and a diol. 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.

The base paper in the present invention is made by laminating and integrating the above-mentioned thermoplastic resin film and a porous support mainly composed of synthetic fibers. The lamination may be carried out by using an adhesive under the condition that the perforation sensitivity of the film is not lowered, or the film and the support may be thermally bonded without using the adhesive. From the viewpoint of printing clarity, it is preferable to directly fix the thermoplastic resin film and the porous support by heat 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.

In the present invention, it is particularly preferable to co-stretch an unstretched thermoplastic resin film and a porous support made of synthetic fiber having a low degree of orientation while being thermocompression bonded. That is, by co-stretching the film and the support fiber, the film can be stretch-oriented and the support fiber can also be stretch-oriented. At this time, the fiber diameter distribution of the support fibers can be controlled within a range suitable for the heat-sensitive stencil sheet by specifying the stretching conditions. At this time, the molecular orientation distribution of the film is specified, so that a base paper having excellent perforation properties such as a thermal head can be obtained. Further, by co-stretching, the fibers of the support are stretched in a state of being fused to each other at their entanglement points, so that a mesh suitable for the support can be formed, and the ink permeability and the holding property are balanced. Can be one. Furthermore, by co-stretching the both together, the thermoplastic resin film and the porous support are directly fixed and integrated at their contact points, so that it is not necessary to use an adhesive and the printability is excellent. It can be base paper.

The method of co-stretching is not particularly limited, but biaxial stretching is preferred from the viewpoints of improving the perforation sensitivity of the thermoplastic resin film and specifying the fiber diameter distribution of the support fibers. 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, but in order to obtain a fiber diameter distribution of the support fibers suitable as a base paper, usually 3 to 7 times in each of 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, the base paper of the present invention is preferably heat treated after biaxial stretching. The heat treatment temperature is not particularly limited and is appropriately determined depending on the type of thermoplastic resin used, but in the case of polyester resin, 100 to 240 ° C.
Is preferred.

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 thermoplastic resin film and the porous support may be separated from each other when the base paper is fed and conveyed to the printing machine.

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.

[0039]

[Characteristics measurement method]

(1) Average fiber diameter: dn (μm) Magnification 1000 at 20 arbitrary points of the sample with an electron microscope
A photograph was taken at a magnification of twice, and the diameters of arbitrary 10 fibers were measured for each photograph. This was performed for 20 photographs, and the diameter of 200 fibers was measured in total, and the average value thereof was determined.

(2) Coefficient of variation (%) The standard deviation (σ) was calculated from the above fiber diameter measured value (di) by the following equation, and the coefficient of variation was calculated.

[0041]

[Equation 1]

[Equation 2] (3) Evaluation of printability The prepared base paper is "Lisograph" R manufactured by Ideal Science Co., Ltd.
After being supplied to A205, a plate having a character size of 6 to 10.5 and a circle having a circle (the inside of which is filled in black) of 0.5 to 15 mmφ were prepared as an original by a thermal head plate making system. 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.

(4) Evaluation of running stability When the base paper runs smoothly and no wrinkles are generated on the printing drum, ◯, clogging occurs on the way of the base paper, or wrinkles are generated on the printing drum. What was done was marked with x.

[0043]

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

Example 1 Using a rectangular die having a hole diameter of 0.35 mm and 80 holes, a polyethylene terephthalate raw material ([η] = 0.60, Tm = 254 ° C.) was spun by a melt blow method at a die temperature of 285 ° C. The fibers were taken out and the fibers were dispersed and collected on a conveyor to prepare a nonwoven fabric having an average fiber diameter of 5 μm and a basis weight of 160 g / m ² .

Then, polyethylene terephthalate 85
Copolyester resin raw material ([η] = 0.65, T
m = 211 ° C) is extruded at a T-die mouthpiece temperature of 275 ° 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 80 ° C. to prepare a laminated sheet.

The laminated sheet was placed between heating rolls at 85 ° C.
After stretching 3.5 times in the length direction, it was fed into a tenter type stretching machine, stretched 4.5 times in the width direction at 95 ° C, and further heat-treated at 170 ° C inside the tenter. A wax release agent was applied to the film surface at the inlet of the tenter with a gravure coater to give a dry weight of 0.1 g / m ² to prepare a heat-sensitive stencil sheet.

The fiber basis weight of the obtained base paper was 10.2 g /
m ² , and the film thickness was 1.5 μm. The average diameter of the support fibers is 2.6 μm, and the coefficient of variation is 8.8.
%Met.

Example 2 The polymer discharge amount was changed in Example 1, and the average fiber diameter was 8 μm.
A non-woven fabric having a m and a basis weight of 150 g / m ² was produced.

Then, an unstretched film was produced using the same raw materials as in Example 1. The non-woven fabric is overlaid on the unstretched film and supplied to a heating roll to obtain a roll temperature of 85 ° C.
Was thermocompression bonded to prepare a laminated sheet.

The laminated sheet was placed between heating rolls at 85 ° 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 170 ° C inside the tenter. A wax release agent was applied to the film surface at the inlet of the tenter with a gravure coater to give a dry weight of 0.1 g / m ² to prepare a heat-sensitive stencil sheet.

The fiber basis weight of the obtained base paper was 10.7 g /
m ² , and the film thickness was 1.5 μm. The average diameter of the support fibers was 4.3 μm, and the coefficient of variation was 16.
It was 5%.

Example 3 Similarly, in Example 1, the polymer discharge rate was changed to prepare a nonwoven fabric having an average fiber diameter of 13 μm and a basis weight of 140 g / m ² .

Then, an unstretched film was prepared using the same raw materials as in Example 1. The non-woven fabric is overlaid on the unstretched film and supplied to a heating roll at a roll temperature of 90 ° C.
Was thermocompression bonded to prepare a laminated sheet.

The laminated sheet was placed between heating rolls at 85 ° C.
After stretching 3 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 170 ° C inside the tenter. A wax release agent was applied to the film surface at the inlet of the tenter with a gravure coater to give a dry weight of 0.1 g / m ² to prepare a heat-sensitive stencil sheet.

The fiber basis weight of the obtained base paper was 11.7 g /
m ² , and the film thickness was 1.5 μm. The average diameter of the support fibers was 6.9 μm, and the coefficient of variation was 23.
It was 2%.

Example 4 A polyethylene terephthalate raw material ([η] was used at a die temperature of 280 ° C. using a die having a hole diameter of 0.25 mm and 77 holes.
= 0.66, Tm = 261 ° C.) was spun out and dispersed and collected on a conveyor by an air ejector at a spinning speed of 1400 m / min to prepare a nonwoven fabric having an average fiber diameter of 20 μm and a basis weight of 100 g / m ² .

Then, using the same raw material as in Example 1, an extruder having a screw diameter of 40 mm was used, and the temperature of the T-die base was 2
It was extruded at 80 ° C. and cast on a cooling drum having a diameter of 300 mm to prepare an unstretched film. The non-woven fabric was laid on the unstretched film, supplied to a heating roll and thermocompression bonded at a roll temperature of 85 ° C. to prepare a laminated sheet.

The laminated sheet was stretched 3.5 times in the length direction with a heating roll at 90 ° C., then fed into a tenter type stretching machine and stretched 4 times in the width direction at 95 ° C. Furthermore, it heat-processed at 170 degreeC inside a tenter. In addition, at the inlet of the tenter, a wax-based release agent was applied to the film surface by a gravure coater with a dry weight of 0.1 g / m ² . The fiber basis weight of the obtained base paper was 7.1 g / m ² , and the film thickness was 1.9 μm. The average diameter of the support fibers was 10.3 μm, and the coefficient of variation was 18.9%.

Example 5 The polymer discharge amount was changed in Example 4 to obtain an average fiber diameter of 25.
A non-woven fabric having a micrometer and a basis weight of 100 g / m ² was prepared.

Then, an unstretched film was prepared using the same raw materials as in Example 1. The non-woven fabric is overlaid on the unstretched film and supplied to a heating roll at a roll temperature of 80 ° C.
Was thermocompression bonded to prepare a laminated sheet.

The laminated sheet was placed between heating rolls at 85 ° C.
After stretching 3 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 170 ° C inside the tenter. A wax release agent was applied to the film surface at the inlet of the tenter with a gravure coater to give a dry weight of 0.1 g / m ² to prepare a heat-sensitive stencil sheet.

The fiber basis weight of the obtained base paper was 8.5 g / m.
^{2. The} film thickness was 1.5 μm. The average diameter of the support fibers is 13.4 μm, and the coefficient of variation is 26.
It was 5%.

Comparative Example 1 The polymer discharge amount was changed in Example 1 to obtain an average fiber diameter of 3.
A nonwoven fabric having a weight of 0 μm and a basis weight of 160 g / m ² was prepared.

Then, an unstretched film was prepared using the same raw materials as in Example 1. The non-woven fabric is overlaid on the unstretched film and supplied to a heating roll to obtain a roll temperature of 100.
Thermocompression bonding was performed at 0 ° C. to produce a laminated sheet.

The laminated sheet was placed between heating rolls at 85 ° C.,
After stretching 4 times in the length direction, it was fed into a tenter type stretching machine, stretched 4.5 times in the width direction at 95 ° C, and further heat-treated at 170 ° C inside the tenter. A wax release agent was applied to the film surface at the inlet of the tenter with a gravure coater to give a dry weight of 0.1 g / m ² to prepare a heat-sensitive stencil sheet.

The fiber basis weight of the obtained base paper was 9.0 g / m.
^{2. The} film thickness was 1.5 μm. The average diameter of the support fibers is 1.6 μm, and the coefficient of variation is 7.5%.
Met.

Comparative Example 2 Similarly to Example 1, the polymer discharge amount was changed to prepare a nonwoven fabric having an average fiber diameter of 15 μm and a basis weight of 80 g / m ² .

Then, an unstretched film was prepared using the same raw materials as in Example 1. The non-woven fabric is overlaid on the unstretched film and fed to a heating roll at a roll temperature of 75 ° C.
Was thermocompression bonded to prepare a laminated sheet.

The laminated sheet was placed between heating rolls at 85 ° C.
After stretching 2.5 times in the length direction, it was fed into a tenter type stretching machine, stretched 3.0 times in the width direction at 95 ° C, and further heat-treated at 170 ° C inside the tenter. A wax release agent was applied to the film surface at the inlet of the tenter with a gravure coater to give a dry weight of 0.1 g / m ² to prepare a heat-sensitive stencil sheet.

The fiber basis weight of the obtained base paper was 10.7 g /
m ² , and the film thickness was 1.5 μm. The average diameter of the support fibers is 9.1 μm, and the coefficient of variation is 53.
It was 3%.

Comparative Example 3 The polymer discharge amount was changed in Example 4 to obtain an average fiber diameter of 25.
A non-woven fabric having a thickness of μm and a basis weight of 80 g / m ² was produced.

Then, using the same raw material as in Example 1, an extruder having a screw diameter of 40 mm was used, and the temperature of the T-die base was 2
It was extruded at 80 ° C. and cast on a cooling drum having a diameter of 300 mm to prepare an unstretched film. The non-woven fabric was placed on the unstretched film, supplied to a heating roll, and thermocompression-bonded at a roll temperature of 75 ° C. to prepare a laminated sheet.

The laminated sheet was stretched 2.5 times in the lengthwise direction with a heating roll at 90 ° C., then fed into a tenter type stretching machine, and stretched 2.7 times in the widthwise direction at 95 ° C. Furthermore, it heat-processed at 170 degreeC inside a tenter. In addition, at the inlet of the tenter, a wax-based release agent was applied to the film surface by a gravure coater with a dry weight of 0.1 g / m ² . The fiber basis weight of the obtained base paper was 11.8 g / m ² , and the film thickness was 1.9 μm. The average diameter of the support fibers was 15.5 μm, and the coefficient of variation was 42.2%.

Comparative Example 4 Similarly, in Example 4, the polymer discharge amount was changed and the spinning speed was 5
It was dispersed and collected on a conveyor at 000 m / min to prepare a nonwoven fabric having an average fiber diameter of 15 μm and a basis weight of 18 g / m ² . The coefficient of variation of the fiber diameter of the non-woven fabric was 4.5%. The non-woven fabric was pressure-treated with an embossing roll at 220 ° C., and then the polyester film having a thickness of 1.9 μm prepared in Example 4 was laminated with a vinyl acetate resin, and the film surface was coated with a wax release agent. Then, a base paper for heat-sensitive stencil was prepared.

[0076]

[Table 1] As can be seen from the results in Table 1, the base paper having a support fiber having an average diameter of 2 to 15 μm and a coefficient of variation of 5 to 50% has good printability and excellent runnability and wrinkle resistance.

[0077]

In the heat-sensitive stencil sheet of the present invention, the average diameter of the fibers constituting the porous support and the coefficient of variation thereof are specified, and the support is a mixture of different fiber diameters. It is possible to obtain a base paper that satisfies both stability and wrinkle resistance at the same time.

Claims (5)

[Claims] 1. A thermoplastic resin film having an average fiber diameter of 2
A base paper for a heat-sensitive stencil, which is obtained by laminating a porous support mainly composed of synthetic fibers having a size of ˜15 μm, wherein the synthetic fibers have a fiber diameter distribution with a coefficient of variation of 5 to 50%. Raw paper. 2. The fibers of the porous support form a mesh-like body in which the fibers are irregularly fused to each other at the points of entanglement, and a thin film fold is formed on a part of the fused portion. The base paper for heat-sensitive stencil according to claim 1, wherein 3. The heat-sensitive stencil sheet according to claim 1 or 2, wherein the thermoplastic resin film and the synthetic fiber constituting the porous support are directly fixed at their contact points. 4. The heat-sensitive stencil sheet according to claim 1, wherein the synthetic fiber is made of a polyester resin. 5. The base paper for heat-sensitive stencil according to any one of claims 1 to 3, wherein the thermoplastic resin film is made of polyester resin.