JPH11157239A - Heat sensitive stencil printing base sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high image quality by preventing a plate attaching wrinkle in a printed matter attained in a stencil printing using a heat sensitive stencil printing base sheet. SOLUTION: The heat sensitive stencil printing base sheet obtained by laminating a thermoplastic resin film and a porous support made of thermoplastic resin fibers without adhesive comprises a fiber layer having a circular section and a fiber layer having an elliptical section in the support. In this support, the layer having the circular section is disposed at the film side, and the layer having the elliptical section is disposed on an outer surface.

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. More specifically, the present invention relates to a heat-sensitive stencil sheet which is perforated and made by a thermal head or a laser beam, and particularly relates to a heat-sensitive stencil sheet which does not generate plate wrinkles and provides a high quality printed matter. .

[0002]

2. Description of the Related Art In recent years, a thermal stencil printer has been designed to increase the dot density of a thermal head from 400 dpi to 6 dots for the purpose of high resolution.
Improvements such as reducing the energy of plate making of a thermal head have been made in order to increase the plate making speed to 00 dpi and to shorten the plate making speed. For this purpose, high-sensitivity and high-quality heat-sensitive stencil printing base paper (hereinafter referred to as base paper) is used. ) Is required.

In order to meet these demands, improvements have been made such as reducing the thickness of a film for the purpose of improving sensitivity, increasing the heat shrinkage and heat shrinkage stress of the film, and improving the image quality. For the purpose, improvements have been made such as using synthetic fibers for the support to make the fibers thinner and the basis weight smaller.

[0004] However, even if the sensitivity of the film is improved, the conventional base paper having a structure in which the support and the film are bonded to each other with an adhesive has a problem that the binder or the adhesive in the support partially forms aggregates to form an ink. And there is a problem that white spot defects occur in printed matter. In addition, it was found that when the film was made thinner or the fiber diameter and the basis weight of the support were reduced, there were problems such as wrinkling and lamination of the film when the film and the support were laminated.

In order to solve these problems, the present inventors have disclosed Japanese Patent Application Laid-Open Nos. Hei 6-305273 and Hei 7-18.
No. 6565 and the like have proposed a heat-sensitive stencil printing base paper obtained by thermally bonding an unstretched polyester film and an unstretched polyester fiber and biaxially stretching them.

[0006] Since the base paper is formed by integrating a thin film and a support without using any binder or adhesive, the perforation sensitivity of the film is high, and a good image can be obtained by printing with the base paper. Can be

However, it has been found that the base paper is liable to cause plate wrinkles, and the printing quality of a low-resolution (300 dpi) printing machine is conversely degraded in image quality.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and eliminates the occurrence of wrinkles on the plate.
An object of the present invention is to provide a heat-sensitive stencil sheet having good image properties.

[0009]

Means for Solving the Problems In view of the above problems, as a result of diligent studies, it has been found that this can be achieved by forming the support of the base paper with fiber layers having different cross-sectional shapes, and the present invention has been accomplished.

That is, the present invention relates to a heat-sensitive stencil sheet obtained by laminating a thermoplastic resin film and a porous support made of thermoplastic resin fibers without using an adhesive, wherein the porous support has a circular cross section. And a fibrous layer having an elliptical cross-section.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The thermoplastic resin film and the thermoplastic resin fiber of the present invention include polyester, polyamide, polyethylene, polypropylene, their copolymers, and blends thereof. Polyester and its copolymer or blend are used for both the plastic resin film and the thermoplastic resin fiber. As the polyester, a polyester containing an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid, or an alicyclic dicarboxylic acid and a diol as main components is preferable. Here, as the aromatic dicarboxylic acid component, for example, terephthalic acid, isophthalic acid, phthalic acid,
4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4 ′
-Diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid and the like can be used, and terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid and the like are particularly preferable. Can be. As the aliphatic dicarboxylic acid component, for example, adipic acid, suberic acid, sebacic acid, dodecandioic acid and the like can be used, and among them, adipic acid and the like can be preferably used. As the alicyclic dicarboxylic acid component, for example, 1,4-cyclohexanedicarboxylic acid or the like can be used. One of these acid components may be used alone, or two or more thereof may be used in combination. 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. These diol components may be used alone or in combination of two or more.

The polyester used for the thermoplastic resin film of the present invention is preferably polyethylene terephthalate, a copolymer of ethylene terephthalate and ethylene isophthalate, a copolymer of ethylene terephthalate and ethylene naphthalate, and hexamethylene terephthalate and cyclohexanediphthalate. Copolymers of methylene terephthalate, blends of polyethylene terephthalate and polybutylene terephthalate, and the like can be used. Particularly preferably, a copolymer of ethylene terephthalate and ethylene isophthalate, a copolymer of ethylene terephthalate and ethylene naphthalate, and the like can be used from the viewpoint of perforation sensitivity and stretchability.

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 siloxane can be blended. Further, lubricity can be imparted as required. There is no particular limitation on the method of imparting lubricity, but, for example, clay, mica, titanium oxide, calcium carbonate, kaolin, talc, inorganic particles such as wet or dry silica, acrylic acid, organic particles containing styrene and the like as constituents And the like, a method using so-called internal particles for precipitating a catalyst or the like to be added during the polyester polymerization reaction, a method using a surfactant, and the like.

As the polyester used for the thermoplastic resin fiber in the present invention, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, a copolymer of ethylene terephthalate and ethylene isophthalate, and the like can be preferably used. Particularly preferably, polyethylene terephthalate, polyethylene naphthalate and the like can be used from the viewpoint of thermal dimensional stability.

The thermoplastic resin fiber 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 siloxane can be blended.

The thermoplastic resin fiber of the present invention may be subjected to a chemical treatment such as an acid or alkali treatment, a corona treatment, a low-temperature plasma treatment or the like on the surface of the fiber, if necessary, in order to impart an affinity for the ink. Good.

The base paper of the present invention is formed by laminating a film and a porous support without using an adhesive. Adhesion using an adhesive is not preferable because white spots occur.

It is essential that the porous support of the present invention comprises a fiber layer having a circular cross section and a fiber layer having an elliptical cross section. A fiber made of only a fiber having a circular cross section is not preferred because plate-form wrinkles easily occur. According to the present invention, by forming a fiber layer having a circular cross section and a fiber layer having an elliptical cross section, it is possible to prevent plate wrinkles without deteriorating image quality.

The porous support of the present invention preferably has a layer structure in which fiber layers having a circular cross section and fiber layers having an elliptical cross section are alternately laminated. More preferably, a fiber layer having a circular cross section is disposed on the side in contact with the film, and a fiber layer having an elliptical cross section is disposed on the outer surface.

In the porous support of the present invention, the ratio of the fiber layer having a circular cross section to the fiber layer having an elliptical cross section can be set arbitrarily. It is at least 10% of the thickness of the whole support, more preferably 20 to 80%, particularly preferably 30%.
~ 70%. It is particularly preferable that the thickness of the fiber layer having an elliptical cross section is within the above range, since the plate formation wrinkles can be suppressed without deteriorating the image quality.

In the fiber having an elliptical cross section according to the present invention,
The ratio A / B of the major axis (A) and the minor axis (B) of the cross section is 1.2 to 5
And more preferably 1.5 to 5. When A / B is within the above range, plate wrinkles are less likely to occur, which is particularly preferable.

The fineness of the support fiber of the present invention is 0.001 d.
-10d, more preferably 0.00
5d to 5d, particularly preferably 0.01d to 3d.
When the support fineness is in the above range, the strength becomes sufficient, so that it is preferable.

The thickness of the porous support in the present invention is 3
It is preferably from 0 to 120 μm, more preferably from 4 to 120 μm.
It is 0 to 100 μm, particularly preferably 40 to 90 μm. When the thickness of the support is in the above range, the ink retainability is good, and even if a large number of sheets are printed, the image is not blurred, which is preferable.

The basis weight of the porous support in the present invention is 4
-20 g / m ² , more preferably 6 g / m ^2.
１８18 g / m ² , particularly preferably 8 to 16 g / m ² . When the basis weight is in the above range, it is preferable because the ink permeability is good and a clear printed image can be obtained.

The degree of crystallinity of the thermoplastic resin fiber in the present invention is preferably 10% to 50%, more preferably 15% to 50%.
% To 50%, particularly preferably 20% to 50%. When the crystallinity is in the above range, the heat resistance of the support is sufficient, which is preferable.

The thermoplastic resin film of the present invention comprises:
The melting point is preferably at most 230 ° C, more preferably at most 220 ° C, particularly preferably at most 210 ° C. When the melting point is 230 ° C. or lower, the heat perforation property of the film becomes good, and thus it is particularly preferable in terms of sensitivity.

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. If the thickness is 5 μm or less, the piercing property is good,
When the thickness is 0.1 μm or more, the film formation stability is good.

The thermoplastic resin film of the present invention comprises:
The crystal melting energy is preferably 10 to 50 J / g, more preferably 10 to 40 J / g. When the crystal melting energy is in the above range, the perforated shape of the film is stabilized, which is preferable.

The method for producing the heat-sensitive stencil sheet of the present invention is not particularly limited, but the following method is particularly preferred.

That is, two or more layers of an unstretched thermoplastic resin film, a thermoplastic resin fiber layer having a circular cross section and a thermoplastic resin fiber layer having an elliptical cross section are superposed and thermally bonded, and then biaxially co-stretched. Can be manufactured.

The thermoplastic resin film and the thermoplastic resin fiber used in the present invention, for example, in the case of polyester,
It can be manufactured by the following 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 remove the excess diol component and polycondensate to produce a dialkyl acid. There is a method of using an ester, performing a transesterification reaction between the ester and a diol component, and then performing polycondensation in the same manner as described above. At this time, if necessary, a conventionally known alkali metal as a reaction catalyst,
Alkaline earth metals, manganese, cobalt, zinc, antimony, germanium, titanium compounds and the like can also be used.

The unstretched thermoplastic resin film used in the production of the base paper of the present invention may be prepared by using, for example, the above polyester.
For example, it can be manufactured by extruding a polymer onto a cooling drum by a T-die extrusion method. The intrinsic viscosity of the polyester used for the film is preferably 0.5 or more, more preferably 0.6 or more, and particularly preferably 0.65 or more. When the intrinsic viscosity is 0.5 or more, the film-forming stability is good, and particularly, casting of a thin film becomes easy.

The unstretched thermoplastic resin fibers used in the production of the base paper of the present invention can be produced in a nonwoven fabric form by a direct melt spinning method such as a melt blow method or a spun bond method. Melt blown nonwoven fabrics are more preferable in view of co-stretchability with a film and adhesiveness between nonwoven fabrics.

When the melt-blown nonwoven fabric discharges a molten polymer from a die, hot air is blown from a peripheral portion of the die to make the discharged polymer finer, and then the melted polymer is placed on a net conveyor arranged at an appropriate position. It is produced by spraying and collecting. Since the nonwoven fabric is sucked together with the hot air by a suction device provided on the net conveyor, the fibers are collected before the fibers are completely solidified. That is, the fibers are collected in a state where they are fused to each other. By appropriately setting the hot air temperature, the hot air flow rate, or the collection distance between the base and the net conveyor, the degree of fusion between the fibers can be adjusted. Also, by appropriately adjusting the amount of discharged polymer, the temperature of hot air, the flow rate of hot air, the conveyor speed, and the like, the thickness and basis weight of the fibers can be adjusted. The melt-blow spun thermoplastic resin fiber is solidified in a non-oriented or extremely low-oriented so-called undrawn state, and the polymer discharged from the die is rapidly cooled from a molten state to a room temperature atmosphere, so that it is almost amorphous. Since it is solidified in a low crystalline state, it can be made to have excellent co-stretchability with a thermoplastic resin film. The birefringence of the unstretched nonwoven fabric preferably used for the production of the base paper of the present invention is 10 × 10 ⁻³ or less, and the crystallinity is 5% or less.

Although the cross-sectional shape of the melt-blown nonwoven fabric is generally circular, an unstretched nonwoven fabric having an elliptical cross-section can be manufactured by forming the cross-sectional shape of the die hole into an elliptical shape.

The intrinsic viscosity of the polymer used for the melt blown nonwoven fabric is preferably 0.4 or more, more preferably 0.1 wt.
45 or more. If the intrinsic viscosity is 0.4 or more, there is no shot or yarn breakage in the spinning process, and
It is particularly preferable because the fiber is not broken at the time of co-drawing with the film.

In the production of the base paper of the present invention, the method for thermally bonding the unstretched thermoplastic resin film and the unstretched thermoplastic resin fiber layer is not particularly limited, but the thermal bonding using a heating roll is particularly preferred. For example, an unstretched nonwoven fabric having a circular cross section and an unstretched nonwoven fabric having an elliptical cross section may be supplied by being superimposed on a cast unstretched film at the stage of longitudinal stretching in the film production process. Alternatively, the unstretched nonwoven fabric having a circular cross section and the unstretched nonwoven fabric having an elliptical cross section may be previously heat-bonded with a heating roll or the like, and then may be co-stretched by overlapping with an unstretched thermoplastic resin film. Furthermore, in the above-mentioned unstretched nonwoven fabric spinning step, after spinning an unstretched nonwoven fabric having a circular cross section, from above, spinning an unstretched nonwoven fabric having an elliptical cross section to form a laminated nonwoven fabric, The laminated nonwoven fabric and the unstretched thermoplastic resin film may be overlapped and co-stretched. The thermal bonding temperature between the unstretched thermoplastic resin film and the unstretched thermoplastic resin fiber is preferably around the glass transition point (Tg) of the film, and particularly preferably in the range of 50C to 100C. The pressure at the time of heat bonding is preferably in the range of 0.1 to 100 N / cm in roll linear pressure.

The method of co-stretching the thermoplastic resin film and the thermoplastic resin nonwoven fabric is not particularly limited, but biaxial stretching is more preferred. Biaxial stretching can be performed by sequential biaxial stretching or simultaneous biaxial stretching.
Any of the axial stretching methods may be used. In the case of sequential biaxial stretching, it is general that transverse stretching is generally performed by a tenter after longitudinal stretching by a group of heating rolls, but may be reversed. The co-stretching temperature is preferably between 50 ° C and 150 ° C, more preferably between 60 ° C and 130 ° C. Further, in order to uniformly perform heating during stretching, only the unstretched thermoplastic resin nonwoven fabric may be preheated alone and then supplied to the stretching roll. Further, in order to uniformly stretch the film and the nonwoven fabric, the thermally bonded film and the nonwoven fabric may be heated by an infrared heater or the like immediately before stretching.

The magnification of the co-stretching is not particularly limited, but is usually preferably 2 to 8 times each in the longitudinal and transverse directions, more preferably 3 to 8 times.
~ 8 times is appropriate. Also, after biaxial stretching, vertical or horizontal,
Alternatively, they may be co-stretched vertically and horizontally again.

In the above method, the unstretched thermoplastic resin film and the unstretched thermoplastic resin nonwoven fabric are heat-bonded and co-stretched, so that the thermoplastic resin film and the thermoplastic resin fiber pass through an adhesive. Can be adhered without any problems. Also, the thermoplastic resin nonwoven fabrics can be bonded to each other without using an adhesive.

Thereafter, it is preferable to heat-treat the base paper of the present invention after the biaxial co-stretching. Although the heat treatment temperature is not particularly limited, it is preferably in the range of 100 ° C. to 200 ° C., and the treatment time is usually about 0.5 to 60 seconds.

After the base paper obtained by the heat treatment is once cooled to about room temperature, it can be further aged at a relatively low temperature of 40 to 90 ° C. for about 5 minutes to 1 week.
When such aging is employed, curling and wrinkles are less likely to occur during storage of the base paper, which is particularly preferable.

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,
Those composed of a silicone resin, a fluorine resin, a surfactant and the like are preferable. 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, antistatic agents, heat-resistant agents, antioxidants, organic particles, inorganic particles, pigments and the like can be mentioned.

The thickness of the release agent layer is preferably 0.005 μm.
m or more and 0.4 μm or less, more preferably 0.01 μm or more and 0.2 μm or less. The thickness of the release agent layer is 0.005 μm
If it is above, the runnability of the base paper becomes good, and the thickness is 0.1 mm.
If it is 4 μm or less, there is no contamination of the thermal head.

The release agent may be applied at any stage before or after the film is stretched. The application method is not particularly limited, but the application can be appropriately performed using a roll coater, a gravure coater, a reverse coater, a bar coater, or the like.

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 as needed.

Next, a method for measuring and evaluating characteristics according to the present invention will be described.

(1) Cross-sectional shape of fiber A cross section of the base paper in the thickness direction was cut out with a microtome, and a photograph at a magnification of 500 to 1000 was taken with an electron microscope and observed.

(2) Thickness of support fiber layer (μm) A cross section in the thickness direction of the base paper was cut out, and magnification of 5 was observed with an electron microscope.
Photos were taken at a magnification of 00 to 1000 times and the thickness was determined.

(3) Weight (g / m ² ) After carefully peeling the film from the base paper,
It was cut out to a size of cm, weighed, and converted to a weight per m ² .

(4) Film Thickness (μm) The thickness was measured using a light interference type thickness meter (HIT25 manufactured by Toray Techno Co., Ltd.).

(5) Evaluation of Plate Wrinkles The prepared base paper was supplied to a printing machine “RISOGRAPH” (TR135) manufactured by Riso Kagaku Kogyo Co., Ltd. Was determined.

◎: No wrinkles were generated. 回: One time was generated. ２: Two times was generated. Δ or above is a level that can be practically used.

(6) Evaluation of Image Quality The produced base paper was supplied to a printing machine “Risograph” (TR135) manufactured by Riso Kagaku Kogyo Co., Ltd., and printed using all B4 size solid originals. With respect to the twentieth print sample, white spots and shading were visually observed and judged as follows.

<Blank spots> な い indicates no blank spots, を indicates very few blank spots, △ indicates that white spots are slightly conspicuous, and × indicates marked white spots. Δ or above is a level that can be practically used.

<Shading unevenness> A sample having no shading was evaluated as ◎ A shading with slight shading was observed, a shading was slightly noticeable, and a shading was marked as x. Δ or above is a level that can be practically used.

[0057]

The present invention will be described in more detail with reference to the following examples.

Example 1 Using a melt blow spinning machine having a circular hole (diameter: 0.3 mm), a die temperature of 290 ° C. and a hot air temperature of 2
95 ° C., a discharge rate of 30g / min, spun polyethylene terephthalate material ([η] = 0.495, Tm2 = 254 ℃) , fineness 0.5d, unstretched nonwoven having a circular cross-section having a basis weight of 60 g / m ² ( A) was prepared. Next, a non-stretched nonwoven fabric (B) having an elliptical cross-section having a fineness of 0.5 d and a basis weight of 60 g / m ² was produced by changing the die having an oval hole (major axis: 0.45 mm, minor axis: 0.3 mm).

Then, a copolymerized polyester resin raw material ([η] = 0.70, Tm1 = 2) comprising 80 mol% of ethylene terephthalate and 20 mol% of ethylene isophthalate.
(00 ° C.) using a 40 mm screw diameter extruder at a T die die temperature of 275 ° C., and cast on a cooling drum having a diameter of 300 mm to produce an unstretched film.

The unstretched film, the unstretched nonwoven fabric (A) and the unstretched nonwoven fabric (B) were superposed and supplied to a longitudinal stretching machine, stretched 3.5 times in the longitudinal direction, and cooled to room temperature. At this time, the non-stretched nonwoven fabric (A) having a circular cross section was overlapped so as to be on the film surface side. At this time, the set temperature of the four preheating rolls of the vertical stretching machine is 8 in order from the front.
The temperature was set at 2 ° C, 84 ° C, 86 ° C, and 88 ° C. The temperature of the stretching roll was 90 ° C., and the nip linear pressure was 20 N / cm. Immediately before the stretching roll, the film surface side was heated at 0.8 kW by an infrared heater.

Then, it is sent to a tenter type horizontal stretching machine,
The film was stretched 3.8 times in the width direction at a preheating temperature of 90 ° C. and a stretching temperature of 95 ° C., and was further heat-treated at 110 ° C. in a tenter and wound into a roll. A heat-sensitive stencil sheet of the present invention was prepared by applying a silicone release agent to the film surface.

The base paper had a film thickness of 1.5 μm, the basis weight of the support fiber was 10 g / m ² , and the thickness of the support was 75 μm. The fineness of the fiber layer having a circular cross section on the film surface side was 0.14 d and the thickness was 35 μm, and the fineness of the fiber layer having an elliptical cross section on the outer surface was 0.15 d and the thickness was 40 μm.

Example 2 Example 1 was the same as Example 1 except that the fiber layer (B) having an elliptical cross section was overlapped so as to be on the film surface side.
In the same manner as in the above, a heat-sensitive stencil sheet was prepared.

The base paper had a film thickness of 1.5 μm, the basis weight of the support fiber was 10 g / m ² , and the thickness of the support was 75 μm. The fineness of the fiber layer having an elliptical cross section on the film surface side was 0.15 d and the thickness was 40 μm, and the fineness of the fiber layer having a circular cross section on the outer surface was 0.14 d and the thickness was 35 μm.

Comparative Example 1 In Example 1, the fineness was 0.5 d and the basis weight was 120 g / m ^2.
An unstretched nonwoven fabric having a circular cross section was prepared. Then
Under the same conditions as in Example 1, a heat-sensitive stencil sheet was prepared.

The base paper had a film thickness of 1.5 μm, the basis weight of the support fiber was 10 g / m ² , the fineness was 0.14 d, and the thickness of the support was 70 μm.

[0067]

[Table 1]

As shown in Table 1, in Examples 1 and 2 of the present invention in which the porous support was composed of a fiber layer having a circular cross section and a fiber layer having an elliptical cross section, plate wrinkles occurred at all. And the image quality was good. On the other hand, in the case of Comparative Example 1 in which the porous support was composed of only fibers having a circular cross section, wrinkling occurred frequently.

[0069]

According to the heat-sensitive stencil printing paper of the present invention, since the support is composed of a fiber layer having a circular cross section and a fiber layer having an elliptical cross section, stencil wrinkling occurs in stencil printing using the base paper. A clear image with no white spots or uneven shading can be obtained.

Claims (5)

[Claims] 1. A heat-sensitive stencil sheet obtained by laminating a thermoplastic resin film and a porous support made of thermoplastic resin fibers without using an adhesive, wherein the porous support has a circular cross section. A heat-sensitive stencil sheet comprising a layer and a fiber layer having an elliptical cross section. 2. The heat-sensitive stencil printing according to claim 1, wherein a fiber layer having a circular cross section is disposed on the film side and a fiber layer having an elliptical cross section is disposed on the outer surface of the porous support. Base paper. 3. The heat-sensitive stencil printing according to claim 1, wherein the thickness of the fiber layer having an elliptical cross section in the porous support is 10% or more of the total thickness of the support. Base paper. 4. The base paper for heat-sensitive stencil printing according to claim 1, wherein the thermoplastic resin film is a polyester film. 5. The thermoplastic resin film for heat-sensitive stencil printing according to claim 1, wherein the thermoplastic resin fiber is a polyester fiber.