JP2000118162A - Unwoven fabric for heat sensitive stencil printing original paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a dimensional stability upon processing and a printed image by a method wherein a principal fiber for constituting the part of skeleton is formed of polyester, whose principal constituent is polyethylene terephthalate, while non-oriented fiber, constituting the part of binder, is formed of a polyester, whose principal constituent is polyethylene naphthalate. SOLUTION: An unwoven fabric is constituted of a principal fiber, constituting the part of a skeleton, and a non-oriented fiber, constituting the part of binder. The principal fiber, constituting the part of a skeleton, consists of a polyester, whose principal constituent is polyethylene terephthalate and whose ethylene terephthalate unit is 80 mol% or more of repeating unit. On the other hand, the non-oriented fiber, constituting the part of binder and low in the orientation of the fiber, is constituted of a polyester, whose principal constituent is polyethylene naphthalate, and 80 mol% or more of the repeated unit is the unit of ethylene-2 and naphthalate-6. According to this method a dimensional stability upon process can be improved and a printed image can also be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a nonwoven fabric for heat-sensitive stencil printing base paper. More specifically, the present invention relates to a nonwoven fabric used for a porous support constituting a heat-sensitive stencil sheet, and to a nonwoven fabric which has excellent dimensional stability and provides a good image.

[0002]

2. Description of the Related Art Conventionally, as heat-sensitive stencil printing paper, porous paper such as thin paper made of a thermoplastic resin film such as vinylidene chloride-vinyl chloride copolymer film, polypropylene film or polyester film and natural fibers such as manila hemp has been used. A structure in which a support and a support are bonded together with an adhesive is well known (JP-B-41-7623 or JP-A-51-2513). However, tissue paper containing natural fibers such as Manila hemp is susceptible to humidity, and therefore absorbs and expands particularly in humid conditions such as during the rainy season. For this reason, the base paper laminated with the thermoplastic resin film has a drawback that it is curled and changes in dimensions are large.

[0003] As a porous support, a mixture of natural fibers and some synthetic fibers may be used (Japanese Patent Publication No. 48-82).
No. 17 or JP-A-60-217197),
Although it has been proposed to impregnate the entire porous support with a synthetic resin (Japanese Patent Publication No. 55-47997), no satisfactory resin has yet been obtained.

For example, a porous support mixed with chemical fibers hardly contributes to dimensional stabilization when wet due to poor adhesiveness of natural fibers to natural fibers, and the entire porous support is impregnated with a synthetic resin. In this case, a decrease in print sharpness due to poor transmission of the printing ink is inevitable.

Further, nonwoven fabrics using 100% of a hydrophobic synthetic fiber such as polyester as a porous support have been proposed (JP-A-59-2896, JP-A-60-38193, JP-A-2-67197 or JP-A-3-76894), although the dimensional stability when wet is improved, there is a disadvantage that shrinkage occurs due to heat received from a thermal head during plate making. Was.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems by defining the fibers constituting the non-woven fabric used as the porous support, has excellent dimensional stability during plate making, An object of the present invention is to provide a non-woven fabric for heat-sensitive stencil printing paper that provides a good image.

[0007]

In the nonwoven fabric for heat-sensitive stencil printing paper of the present invention which achieves the above-mentioned objects, the main fiber constituting the skeleton portion is made of polyester mainly composed of polyethylene terephthalate, and the non-woven fabric constituting the binder portion is formed. A nonwoven fabric for heat-sensitive stencil printing paper, wherein the drawn fiber is made of polyester mainly composed of polyethylene naphthalate.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

The nonwoven fabric of the present invention comprises a main fiber constituting a skeleton portion and an undrawn fiber constituting a binder portion. Adhesion of the main fibers with an adhesive or the like without using unstretched fibers is not preferred because the adhesive inhibits the transmission of ink and reduces the image clarity.

In the present invention, the main fibers constituting the skeleton portion are made of polyester mainly composed of polyethylene terephthalate. Polyester mainly composed of polyethylene terephthalate means that at least 7
It is a polyester having 0 mol% as an ethylene terephthalate unit. It is preferably at least 80 mol%, more preferably at least 85 mol%. If the amount of the ethylene terephthalate unit is less than 70 mol%, not only is the shrinkage during plate making increased, but also the rigidity is reduced, so that wrinkles are easily formed in the printing machine, which is not preferable.

In addition, as long as it is 30 mol% or less of the repeating unit, it may be modified with the following copolymer components. Examples of the copolymer component include components having a divalent ester-forming functional group such as a dicarboxylic acid component and a diol component. More specifically, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4 Aromatic dicarboxylic acids such as' -diphenyldicarboxylic acid, 4,4'-diphenylether dicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, 5-sodium sulfoisophthalic acid, succinic acid, adipic acid, suberic acid, sebacic acid, etc. Aliphatic dicarboxylic acids, alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,2-
Propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-
Butanediol, 1,5-pentanediol, 1,6-
Examples thereof include diols such as hexanediol, 1,4-cyclohexanedimethanol, diethylene glycol, polyalkylene glycol, and 2,2′-bis (4′-β-hydroxyethoxyphenyl) propane.
These may be used alone or in combination of two or more, and further, an oxyacid such as hydroxybenzoic acid may be partially copolymerized.

The main fiber in the present invention preferably has a highly oriented birefringence Δn of 0.15 to 0.25, more preferably 0.18 to 0.25. In density,
It is preferably in the range of 1.38 to 1.41 g / cm ³ .
In the case of polyethylene terephthalate, the crystallinity is 30.
６５65%.

In the present invention, the undrawn fibers constituting the binder portion are made of a polyester mainly composed of polyethylene naphthalate. The polyester mainly composed of polyethylene naphthalate means that at least 70 mol% of the repeating units are ethylene-2,6-naphthalate units. Preferably it is 80 mol% or more, more preferably 85 mol% or more.
Mol% or more. If the content of the ethylene-2,6-naphthalate unit is less than 70 mol%, the shrinkage during plate making is undesirably increased. If it is 30 mol% or less, it may be modified with the following copolymer components.

Examples of the copolymerization component include those similar to the terephthalic acid and the copolymerization component of the main fiber of the present invention except for 2,6-naphthalenedicarboxylic acid.

"Undrawn" means that the fiber orientation is low, and Δn is preferably 0.12 or less. It is more preferably at most 0.10, further preferably at most 0.08. If the orientation of the fibers is low, the adhesive force with the main fibers is strong, and the fibers are less likely to fall off, which is preferable. If Δn is 0.12 or less, a sufficient adhesive strength can be obtained.

The fiber diameter of the main fibers constituting the nonwoven fabric of the present invention is preferably 1 to 12 μm, more preferably 3 to 8 μm. The fiber diameter of the undrawn fiber is preferably 4 to 20 μm, more preferably 5 to 15 μm. The smaller the fiber diameter is, the more uniform the printed image becomes, which is preferable. Both the main fiber and the unstretched fiber may have any cross-sectional shape, but the unstretched fiber is preferably flat. In this case, it is particularly preferable that the portion corresponding to the major axis of the cross section is within the above-mentioned fiber diameter. Further, both the main fiber and the undrawn fiber may be continuous fibers, but more preferably short fibers of about 1 to 15 mm.

In the present invention, the mixing ratio of the main fiber and the undrawn fiber constituting the binder portion is 50:50 to 50:50.
A range of 95: 5 is preferred, and a range of 70:30 to 90:10 is more preferred. When the mixing ratio of the main fibers is high, the printed image becomes good, and when the mixing ratio of the undrawn fibers increases, the falling off of the fibers can be suppressed, and the above range is a preferable range in which shrinkage during plate making can be suppressed and other characteristics can be balanced. It is.

The basis weight of the nonwoven fabric of the present invention is preferably 2
-20 g / m ² , more preferably 3-15 g / m ^2
2 When the basis weight is ² to 20 g / m ² , ink permeability is good and image quality is good. Also, the basis weight is 3 to 15
With g / m ² , more sufficient strength can be obtained, which is preferable.

The thickness of the nonwoven fabric of the present invention is preferably 15
To 100 μm, more preferably 25 to 60 μm.
When the thickness is 15 to 100 μm, the ink permeability is good and the image quality is good. Further, it is more preferable that the thickness is 25 to 60 μm, because the loss of ink at the time of plate discharge is small.

The tensile modulus of the nonwoven fabric of the present invention is preferably 0.10 N / mm, more preferably 0.15 N / mm.
It is. When the tensile modulus is 0.10 N / mm or more,
Low elongation when printing is repeated and 0.15N
/ Mm or more, generation of wrinkles in the printing press is particularly suppressed.

The nonwoven fabric of the present invention is mainly intended for fibers made of polyester. However, it is acceptable to mix a third component which does not impair the basic performance such as rigidity of the nonwoven fabric, ink permeability and shrinkage. Absent.

As the third component, natural fibers such as mulberry, mitsumata, and manila hemp, polyvinyl alcohol,
Acrylic or aramid synthetic fibers or the like can be used.

Next, the method for producing the nonwoven fabric of the present invention will be described below.

In the present invention, the polyester used for the main fiber and the undrawn fiber may be, for example, an esterification reaction of a dicarboxylic acid component with a diol component, and then heating the product of the reaction under reduced pressure to obtain an excess of diol. A method of producing by performing polycondensation while removing components, a method of using a dialkyl ester as a dicarboxylic acid component, performing a transesterification reaction with this and a diol component, and then performing polycondensation in the same manner as described above, and the like. There is. At this time, if necessary, an alkali metal, an alkaline earth metal, manganese, cobalt, zinc, antimony, germanium, and a titanium compound can be used as a reaction catalyst.

In the present invention, the polyester 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 fatty acid ester, a wax, or a polysiloxane. A foaming agent or the like can be blended.

The polyester used for the undrawn fiber and the main fiber can be obtained in the same manner as described above, except that the main component is polyethylene terephthalate or the main component is polyethylene naphthalate.

Next, undrawn fibers can be obtained by a melt spinning method using a polyester mainly composed of polyethylene naphthalate.

The main fiber is made of polyester mainly composed of polyethylene terephthalate.
It can be obtained by stretching.

Each of the main fiber and the undrawn fiber is preferably cut into a predetermined length to be a short fiber.

The obtained main fibers and undrawn fibers are mixed and dispersed in water at a predetermined ratio with a pulper or a beater, and then formed on a circular, short or long net paper machine. Raw cotton is obtained by crimping.

For the nonwoven fabric of the present invention, the calendering conditions are as follows: for example, a sheet prepared at a paper dryer temperature of 110 to 150 ° C. is heated to a temperature lower than the lower one of the melting temperatures of the polyesters of the main fiber and the undrawn fiber. At a temperature of, for example, 180 to 240 ° C. As a calendering method, either a single-stage method or a multi-stage method can be used.

If necessary, the raw cotton or the nonwoven fabric constituting the nonwoven fabric may be subjected to an antistatic treatment, or a hydrophilic treatment may be performed to increase the ink permeability of the nonwoven fabric.

In order to form a heat-sensitive stencil sheet using the nonwoven fabric of the present invention, for example, an acrylic, vinyl chloride, polyester, vinyl acetate, urethane, etc. It is possible to apply an adhesive of a system or the like so that the dry application amount is 0.1 to 1 g / m ² , and to superimpose and press, heat, dry, or irradiate with ultraviolet rays or the like. Further, in order to prevent fusion with the thermal head, a release agent such as a fluorine-based, silicone-based or surfactant may be provided on the surface of the film opposite to the nonwoven fabric.

[0034]

[Method of measuring characteristics] (1) Average fiber diameter: The average fiber diameter is
Ten photographs were taken of arbitrary 10 places of the non-woven fabric with an electron microscope at a magnification of 2000 times, and arbitrary 1 was taken per photograph.
The diameters of five fibers were measured, and the measurement was performed on ten photographs. The diameters of a total of 150 fibers were measured, and the average value was shown.

(2) Birefringence (Δn): A birefringence (Δn) was calculated by using a sodium lamp as a light source with a polarizing microscope and determining the retardation of the sample by the Berk compensator method while immersing the sample in α-bromonaphthalene.

(3) Weight per unit area: The nonwoven fabric was cut into a size of 20 × 20 cm, the weight was measured, and the value converted to the weight per square meter was used.

(4) Tensile elastic modulus: A base paper was cut in a length direction and a width direction by 20 mm × 150 mm, and was gripped by an air chuck of a “Tensilon” tensile tester (manufactured by Toyo Sokki Co., Ltd.) to determine the elastic modulus. It was measured. The measurement conditions were a chuck interval of 50 mm and a tensile speed of 50 mm / min, and a load-elongation diagram (SS curve) was recorded. It was calculated by dividing the tensile load at an elongation of 1% by the sample width from the initial rising slope of the SS curve.

(5) Plate making shrinkage: Marking is made at intervals of 200 mm in the length direction on the nonwoven fabric surface side of the base paper and at intervals of 100 mm in the width direction. It was supplied to a RISOGRAPH "TR153, and a plate made of a B4 plate having an area of 360 mm × 260 mm and a solid black was used as a plate. After plate making, remove the base paper from the printing press,
The interval between marks was measured with high precision, and the shrinkage was calculated.

The level of 0.2% or less in both the length and width directions is a practically usable level.

(6) Image quality: base paper is Riso Kagaku Kogyo Co., Ltd.
The plate was supplied to "RISOGRAPH" GR375, and plate making and printing were performed using a black solid document as a document. Twenty sheets were printed, and the state of white spots and density unevenness of the twentieth printed image was visually determined based on the following criteria.

<White spots> No white spots, "O" White spots were slightly observed, "△" White spots were noticeable, "x"<Light and light spots> No spots And “「 ”indicates that the unevenness is slightly observed,“ △ ”indicates that the unevenness is conspicuous, and“ × ”. Here,“ ○ ”or“ △ ”is a practically usable level.

[0042]

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 [Preparation of main fiber] A polyethylene terephthalate chip was melted at 290 ° C and passed through a die having 900 holes.
It was discharged at 5 ° C. and wound up at a speed of 1000 m / min. Next, the undrawn yarn is drawn at a magnification of 3.8 times in warm water at 80 ° C., subjected to a tension heat treatment at 200 ° C., a relaxation heat treatment at 125 ° C., cut into 5 mm, and birefringent at an average fiber diameter of 5 μm. Was 0.20.

[Production of Undrawn Fiber] On the other hand, a polyethylene naphthalate chip was melted at 295 ° C.
At 290 ° C. and cut into 5 mm to obtain undrawn fiber a having an average fiber diameter of 8 μm and a birefringence of 0.05.

[Paper making] The main fiber A and the undrawn fiber a
After thoroughly mixing and dispersing in a pulper at a weight ratio of 0:20, the mixture was heated and dried at a speed of 9 m / min at a surface temperature of a Yankee dryer of 130 ° C. using a circular paper machine. The weight per unit area is 10
g / m ² .

Then, the metal roll surface temperature was 215 ° C. and the linear pressure was 20 kg / cm using a metal / elastic roll calendering machine.
Under the following conditions to obtain a nonwoven fabric having a thickness of 25 μm.

[Production of base paper] A 2 μm-thick biaxially stretched film made of a copolymer of ethylene terephthalate and ethylene isophthalate (isophthalic acid copolymerization amount: 15 mol%) was prepared by using a vinyl acetate adhesive. The above nonwoven fabric was adhered, and a silicone release material was applied to the opposite surface of the film from the nonwoven fabric side to obtain a base paper.

[Evaluation] The properties of the obtained base paper are shown in Table 1. It can be seen that the base paper has excellent dimensional stability during plate making and also has good image quality.

Comparative Example 1 [Production of Undrawn Fiber] On the other hand, a polyethylene terephthalate chip was melted at 290 ° C., discharged at 285 ° C. through a die having 900 holes, cut into 5 mm, and cut to an average fiber diameter of 8 mm.
An undrawn fiber b having a birefringence of 0.05 μm was obtained.

[Paper making] The main fiber A and the undrawn fiber b
After thoroughly mixing and dispersing in a pulper at a weight ratio of 0:20, the mixture was heated and dried at a speed of 9 m / min at a surface temperature of a Yankee dryer of 130 ° C. using a circular paper machine. The weight per unit area is 10
g / m ² .

Next, the metal roll surface temperature was 210 ° C. and the linear pressure was 15 kg / cm using a metal / elastic roll calendering machine.
Under the following conditions to obtain a nonwoven fabric having a thickness of 25 μm.

[Production of base paper] A 2 μm-thick biaxially stretched film made of a copolymer of ethylene terephthalate and ethylene isophthalate (isophthalic acid copolymerization amount: 15 mol%) was prepared by using a vinyl acetate adhesive. The above nonwoven fabric was adhered, and a silicone release material was applied to the opposite surface of the film from the nonwoven fabric side to obtain a base paper.

[Evaluation] The properties of the obtained base paper are shown in Table 1. As a result, the shrinkage during plate making was large, and wrinkles occurred during plate formation and repeated printing, resulting in poor images. .

Example 2 [Preparation of main fiber] A polyethylene terephthalate chip was melted at 290 ° C and passed through a die having 900 holes.
It was discharged at 0 ° C. and wound up at a speed of 1000 m / min. Next, the undrawn yarn is drawn at a magnification of 3.0 times in warm water of 80 ° C., subjected to a tension heat treatment at 200 ° C., a relaxation heat treatment at 125 ° C., cut into 5 mm, and birefringent at an average fiber diameter of 5 μm. Was 0.15.

[Paper making] The main fiber B and the undrawn fiber a
After thoroughly mixing and dispersing in a pulper at a weight ratio of 0:20, the mixture was heated and dried at a speed of 9 m / min at a surface temperature of a Yankee dryer of 130 ° C. using a circular paper machine. The weight per unit area is 10
g / m ² .

Next, the metal roll surface temperature was 215 ° C. and the linear pressure was 20 kg / cm using a metal / elastic roll calendering machine.
Under the following conditions to obtain a nonwoven fabric having a thickness of 25 μm.

[Production of base paper] A 2-μm-thick biaxially stretched film made of a copolymer of ethylene terephthalate and ethylene isophthalate (isophthalic acid copolymerization amount: 15 mol%) was prepared by using a vinyl acetate adhesive. The above nonwoven fabric was adhered, and a silicone release material was applied to the opposite surface of the film from the nonwoven fabric side to obtain a base paper.

[Evaluation] The properties of the obtained base paper are shown in Table 1. It can be seen that the shrinkage during plate making is small and the image quality is good.

Example 3 [Preparation of Main Fiber] A polyethylene terephthalate chip was melted at 290 ° C., and was passed through a die having 900 holes.
It was discharged at 5 ° C. and wound up at a speed of 1000 m / min. Next, the undrawn yarn is drawn at a magnification of 4.2 times in warm water of 80 ° C., subjected to a tension heat treatment at 200 ° C., further subjected to a relaxation heat treatment at 125 ° C., cut into 5 mm, and birefringent at an average fiber diameter of 5 μm. Was 0.25.

[Paper making] The main fiber C and the undrawn fiber a
After thoroughly mixing and dispersing in a pulper at a weight ratio of 0:20, the mixture was heated and dried at a speed of 9 m / min. At a surface temperature of a Yankee dryer of 130 ° C. using a round paper machine. The weight per unit area is 10
g / m ² .

Then, using a metal / elastic roll calendering machine, the metal roll surface temperature was 215 ° C., and the linear pressure was 20 kg / cm.
Under the following conditions to obtain a nonwoven fabric having a thickness of 25 μm.

[Production of base paper] A 2-μm-thick biaxially stretched film made of a copolymer of ethylene terephthalate and ethylene isophthalate (isophthalic acid copolymerization amount: 15 mol%) was prepared by using a vinyl acetate adhesive. The above nonwoven fabric was adhered, and a silicone release material was applied to the opposite surface of the film from the nonwoven fabric side to obtain a base paper.

[Evaluation] The properties of the obtained base paper are shown in Table 1, and it can be seen that the shrinkage during plate making is small and the image quality is good.

Example 4 [Production of undrawn fiber] On the other hand, a polyethylene terephthalate chip was melted at 290 ° C, discharged at 280 ° C through a die having 900 holes, cut into 5 mm, and cut into an average fiber diameter of 5 mm.
An undrawn fiber b having a birefringence of 0.12 μm was obtained.

[Paper making] The main fiber A and the undrawn fiber b
After thoroughly mixing and dispersing in a pulper at a weight ratio of 0:20, the mixture was heated and dried at a speed of 9 m / min at a surface temperature of a Yankee dryer of 130 ° C. using a circular paper machine. The weight per unit area is 10
g / m ² .

Then, the metal roll surface temperature was 210 ° C. and the linear pressure was 15 kg / c using a metal / elastic roll calendering machine.
By pressing under a condition of m, a nonwoven fabric having a thickness of 25 μm was obtained.

[Production of base paper] A 2-μm-thick biaxially stretched film made of a copolymer of ethylene terephthalate and ethylene isophthalate (isophthalic acid copolymerization amount: 15 mol%) was prepared by using a vinyl acetate adhesive. The above nonwoven fabric was adhered, and a silicone release material was applied to the opposite surface of the film from the nonwoven fabric side to obtain a base paper.

[Evaluation] The properties of the obtained base paper are shown in Table 1. The shrinkage during plate making was small, and the image quality was good.

Example 5 [Papermaking] After sufficiently mixing and dispersing the main fiber B and the undrawn fiber b in a pulper at a weight ratio of 80:20, the speed was 9 m / min using a circular paper machine and the surface temperature of a Yankee dryer. 13
It was dried by heating at 0 ° C. The weight per unit area was 10 g / m ² .

Then, the metal roll surface temperature was 210 ° C. and the linear pressure was 15 kg / cm using a metal / elastic roll calendering machine.
Under the following conditions to obtain a nonwoven fabric having a thickness of 25 μm.

[Production of base paper] A 2-μm-thick biaxially stretched film made of a copolymer of ethylene terephthalate and ethylene isophthalate (isophthalic acid copolymerization amount: 15 mol%) was prepared by using a vinyl acetate adhesive. The above nonwoven fabric was adhered, and a silicone release material was applied to the opposite surface of the film from the nonwoven fabric side to obtain a base paper.

[Evaluation] The properties of the obtained base paper are shown in Table 1. The shrinkage during plate making was small, and the image quality was usable.

Examples 6 to 8 and Comparative Example 2 A base paper was obtained in the same manner as in Example 1 except that the weight ratio between the main fiber A and the undrawn fiber a was changed as shown in Table 1.

[Evaluation] The properties of the obtained base paper are shown in Table 1. The nonwoven fabric of the present invention has excellent dimensional stability during plate making.
It can be seen that the image quality is also good.

Examples 9 and 10 Base papers were obtained in the same manner as in Example 1 except that the basis weight of the paper was changed to 7 g / m ² and 12 g / m ² .

[Evaluation] The properties of the obtained base paper are shown in Table 1. The nonwoven fabric of the present invention has excellent dimensional stability during plate making.
It can be seen that the image quality is also good.

[0077]

[Table 1]

[0078]

The nonwoven fabric for heat-sensitive stencil printing paper of the present invention is
Since it is excellent in dimensional stability at the time of plate making and the image is also good, it is possible to provide a support particularly suitable for heat-sensitive stencil printing base paper.

Continued on the front page F-term (reference) 2H114 AB23 DA56 EA04 EA06 FA02 FA10 4F100 AK22G AK42 AK42B AK79D AS00A BA02 BA04 BA07 BA10A BA10D DG01A DG15A EJ37A GB90 JK04 JK07A JL04 JL14C JN18AFA18 GA4A

Claims (5)

[Claims] The main fiber constituting the skeleton portion is made of a polyester mainly composed of polyethylene terephthalate,
A nonwoven fabric for heat-sensitive stencil printing paper, wherein the unstretched fibers constituting the binder portion are made of polyester mainly composed of polyethylene naphthalate. 2. The nonwoven fabric for heat-sensitive stencil printing paper according to claim 1, wherein the main fiber has a birefringence of 0.15 to 0.25. 3. The nonwoven fabric for heat-sensitive stencil printing paper according to claim 1, wherein the birefringence of the undrawn fiber is 0.12 or less. 4. The heat-sensitive material according to claim 1, wherein the mixing ratio of the main fiber and the undrawn fiber constituting the binder portion is in the range of 50:50 to 95: 5. Non-woven fabric for stencil printing paper. 5. The non-woven fabric for heat-sensitive stencil printing paper according to claim 1, wherein the tensile elastic modulus is 0.10 N / mm or more.