JPH0790762A - Heat-resistant non-woven fabric and production thereof - Google Patents

Abstract

PURPOSE:To obtain a heat-resistant non-woven fabric having high air permeability and flexibility by using polyester fibers and/or polyphenylene sulfide fibers in an extremely low blending rate and pressing the produced web with a low pressure. CONSTITUTION:Wholly aromatic polyamide fibers as a main component are blended with 1-3wt.% of polyester fibers and/or polyphenylene sulfide fibers, and the formed web is heated with the irradiation of far IR light and subsequently pressed with a low pressure to produce the heat-resistant non-woven fabric in which the cross points of the fibers composing the non-woven fabric are thermally adhered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant non-woven fabric comprising a wholly aromatic polyamide fiber as a main constituent and a fiber composed of polyester and / or polyphenylene sulfide as a melting component, and a method for producing the same. Nonwoven fabric has a wide range of applications such as printed wiring base materials, heat-resistant electrical insulation sheets, heat-resistant filters, and heat-insulating and heat-insulating materials that require heat-resistant and flame-retardant properties, which have excellent heat-resistant insulation varnish impregnation properties. Used for.

[0002]

BACKGROUND OF THE INVENTION As a nonwoven fabric having heat resistance, a wet type paper-like nonwoven fabric in which wholly aromatic polyamide fibers, which are heat resistant fibers, are mixed with pulp-like particles of the same kind are widely known. JP-A-59-1818 discloses a method for producing a heat-resistant nonwoven fabric by thermocompression bonding using unstretched wholly aromatic polyamide fibers as an adhesive component.

The above-mentioned non-woven fabric composed of wholly aromatic polyamide fibers and pulp has high density and few voids, and therefore has low air permeability and poor flexibility. Therefore, when it is used as a filter, it has a resistance to liquid or gas passage. Remarkably high. Therefore, the impregnation property of the heat-resistant insulating varnish is low, and it is unsuitable for use as a varnish-impregnated insulating paper or a filter. In addition, since it is difficult to produce a thick non-woven fabric by this wet method, a thick one is produced by laminating a plurality of thin sheets, so that the layers are peeled off by heating and a bubbling phenomenon frequently occurs. It had the drawback of not being practical.

Next, since the nonwoven fabric made of aromatic polyamide fiber and polyester fiber has good heat resistance and excellent mechanical properties, it has been conventionally used for various purposes. For example, Japanese Patent Publication No. 52-27189 discloses a sheet obtained by impregnating a non-woven fabric containing aromatic polyamide fibers and low-oriented polyester fibers with a resin.

Japanese Unexamined Patent Publication No. 60-126400 discloses a paper-like material prepared by wet pressing a slurry prepared by mixing aromatic polyamide fibers and low-orientation polyester fibers and then hot-pressing the slurry, which is impregnated with a resin. Therefore, it can be applied to a flexible printed circuit board.

Further, in Japanese Patent Laid-Open No. 64-40649, mixing of aromatic polyamide fiber and low orientation polyester fiber (wherein 2 to 30% by weight of polyamide is uniformly dispersed in the polyester) is mixed at 50/50. A heat-resistant non-woven fabric characterized by being 80/20 is disclosed.

However, in all of these non-woven fabrics, the low-orientation polyester fiber has a high blending ratio of 15% or more, so that the polyester fiber melts when heat-treated at a temperature above the melting point, so that the dimensional stability of the non-woven fabric cannot be maintained. was there. That is, although the heat resistance was excellent, the heat resistance above the heat melting temperature of the polyester fiber could not be maintained. For example, when a non-woven fabric is impregnated with epoxy resin and further copper foil is attached to one side and floated on a solder bath exceeding 260 to 270 ° C, polyester fibers are melted and deposited on the surface of the epoxy resin. It cannot be used.

On the other hand, polyphenylene sulfide resins are disclosed in Japanese Examined Patent Publication No. 52-80609 and Japanese Patent Laid-Open No. 58-31.
The fiberizing technique disclosed in Japanese Patent Application Laid-Open No. 112 etc. is known, and a short fiber felt by a heat-resistant needle punching method using polyphenylene sulfide fiber and JP-A-57-1 are used.
A long-fiber nonwoven fabric made by the spunbond method of 6954 is known, but all of them are formed by mechanical entanglement, and there is no bond by heat fusion, so that a load is applied for a long time at high temperature. In some cases, shape retention is not sufficient. When the non-woven fabric is thermocompression-bonded in order to provide the heat-bonding bonding points, the whole is formed into a film, and the air permeability and the flexibility are greatly reduced.

Further, undrawn polyphenylene sulfide fiber having a high mixing ratio of 8 to 80% is used as a fusion component at a low temperature (183
The method of pressing at a high linear pressure (30 to 270 kg / cm) at ˜257 ° C.) is disclosed in JP-A-61-289162. In this case, a very large pressure is required, so that there is a mechanical restriction, and the air permeability and flexibility of the obtained nonwoven fabric are greatly reduced, so that the impregnation property of the heat resistant insulating varnish is reduced. Further, when it is used as a filter, the permeability of liquid or gas becomes poor.

Further, as a method for producing a heat-resistant nonwoven fabric according to JP-A-3-137259 and JP-A-3-137260, 97-92% by weight of heat-resistant fiber (whole aromatic polyamide fiber) and 3-8% by weight are used. 245-345 to form a web by blending with the stretched polyphenylene sulfide fiber or the unstretched polyphenylene sulfide fiber.
Pressure heat treatment at ℃ (2 to 100 rolls with linear pressure 5-100)
A method of pressing at (kg / cm) is disclosed.

By the way, when manufacturing a thick non-woven fabric,
Even if pressed with low pressure with two anti-metal rolls to maintain air permeability and flexibility, it is difficult to evenly transmit the heating temperature to the inside of the non-woven fabric, that is, the difference between the surface temperature of the non-woven fabric and the internal temperature. Mechanical properties are not sufficient because they are generated and do not heat-bond uniformly. Therefore, when manufacturing a practical thick nonwoven fabric, there is a limit in thickness (weight).

[0012]

The present invention has been made to solve the above problems, and uses polyamide fibers and / or polyphenylene sulfide fibers having an extremely low mixing ratio,
Moreover, they have found that a heat-resistant nonwoven fabric having breathability and flexibility can be obtained by pressing at a low pressure.

[0013]

In order to solve the above problems, the production method according to the present invention is a method for producing a heat-resistant non-woven fabric excellent in heat-insulating varnish impregnation property by spot-bonding the intersections of the non-woven fabric constituent fibers. In the method, the non-woven fabric-constituting fiber is a wholly aromatic polyamide fiber as a main component, and is a fiber of polyester and / or polyphenylene sulfide, and the point adhesion is 1 wt% or more and 3 wt% of the polyester and / or polyphenylene sulfide fiber.
It is characterized in that it is formed by kneading with less than the above to form a web, followed by light pressurization and heat treatment by irradiation with far infrared rays, and then pressurizing and thermally adhering.

In a preferred embodiment of the present invention, the non-woven fabric-constituting fibers are composed mainly of wholly aromatic polyamide fibers, and polyester fibers and / or polyphenylene sulfide fibers are mixed in an amount of 1% by weight or more and less than 3% by weight to form a web. The temperature of the web is gradually increased by irradiation with far-infrared rays during conveyance by a roller conveying means that is lightly pressed (linear pressure 0.2 to 0.8 kg / cm) in order to point-bond the intersection points of the nonwoven fabric constituent fibers. Is a manufacturing method for obtaining a heat-resistant nonwoven fabric excellent in heat-insulating varnish impregnation by pressurizing at a linear pressure of 1 to 100 kg / cm immediately after the temperature rises to the heat melting temperature of the thermoplastic resin.

The heat-resistant non-woven fabric according to the present invention comprises wholly aromatic polyamide fibers as a main constituent, and polyester and / or
Alternatively, it is characterized in that the intersection points of the non-woven fabric constituent fibers obtained by mixing polyphenylene sulfide fibers in an amount of 1% by weight or more and less than 3% by weight are point-bonded.

The wholly aromatic polyamide fibers used in the present invention include poly-m-phenylene isophthalamide fibers and modified products thereof, and poly-p-phenylene terephthalamide fibers and modified products thereof. Further, while being transported by the roller transporting means, a plurality of heating means are arranged to gradually heat the heating means. As a heating method of the heating means, the web is heated uniformly by the irradiation of far infrared rays, and the inner and outer layers are uniformly heated, so that the surface can be uniformly heated without burning. In the conventional heating method, heat is transmitted in sequence from the surface, whereas far infrared rays directly reach the object to be heated and generate heat without being absorbed by the medium such as the air layer. That is, the web can be spot-heated without raising the ambient temperature, and it is not necessary to seal the heating device. Therefore, the heating efficiency is high and the temperature control is extremely easy.

The web gradually heated by irradiation with far-infrared rays is heated to a heat melting temperature of the thermoplastic resin used as an adhesive component, for example, 260 ° C. for polyester and 290 ° C. for polyphenylene sulfide, and then heated. It is pressed by a calendar roller. The pressure applied by the thermal calendar roller is in the range of linear pressure of 1 to 100 kg / cm, and when the basis weight of the nonwoven fabric is less than 100 g / m ² , the linear pressure is 1 to 10 kg / cm, and 100 to 200 g / m ^2.
The linear pressure in the following cases is 20-50 kg / cm, 200 g /
When the pressure exceeds m ² , the linear pressure is 60 to 100 kg / cm. The surface temperature of the calender roller is preferably set slightly higher than the heat melting temperature in consideration of heat loss and the like.

[0018]

According to the method for producing a heat-resistant nonwoven fabric of the present invention, the point of intersection of the fibers constituting the nonwoven fabric is point-bonded to
It has excellent breathability and flexibility, good impregnation with heat resistant insulating varnish, and excellent mechanical properties, so it is used as a substrate for printed wiring, heat resistant electrical insulation sheets, filters that require heat resistance, and even heat resistance. It can be used in a wide range of applications such as heat insulating materials and heat insulating materials that require heat resistance and flame retardancy.

[0019]

EXAMPLES The present invention will be specifically described below with reference to examples. Example 1 97.5% by weight of wholly aromatic polyamide fiber having a fineness of 2 denier and a fiber length of 51 mm (manufactured by DuPont, trade name "Nomex (registered trademark)"), a fineness of 1.3 denier and a stretched polyester fiber having a fiber length of 38 mm 2.5% by weight and each of them are sufficiently opened by an opener and then uniformly mixed by a mixing device to form an oriented web by a roller card. On the other hand, after making a web with a roller card of another series, laminating the web with a cross layer, and then performing a draft ratio of 1.5 to 2.5 times with a web drafter to adjust the basis weight of the web, The oriented web was superposed to form a web having a basis weight of 100 g / m ² . Next, the web in which the polyester melting temperature was raised to 265 ° C. was heated by a far infrared ceramic heater type heating device, and the surface temperature of the thermal calendar roller was 270 ° C. and the linear pressure was 50 kg / c.
The desired heat resistant nonwoven fabric was obtained by thermocompression bonding with m. Table 1 shows the physical properties of this nonwoven fabric. From Table 1, this non-woven fabric has high strength, breathability, flexibility, good impregnation with heat resistant insulating varnish, low heat shrinkage and weight loss, heat resistant electrical insulating base material, heat resistant filter, heat insulating material, It turns out that it is excellent as a heat insulating material.

Comparative Example 1 A web was formed by the same composition and method as in Example 1,
When thermocompression bonding was performed without using the far infrared ceramic heater type heating device at a surface temperature of a thermal calendar roller of 280 ° C. and a linear pressure of 300 kg / cm, the whole pressure was formed into a film because the pressure bonding conditions were high temperature and high pressure. The air permeability and varnish impregnation were low, and the flexibility was poor and the handling was poor.

Comparative Example 2 A wholly aromatic polyamide nonwoven fabric was obtained by a wet method. Table 1
As shown in, the varnish impregnation property is remarkably poor.

Example 2 98% by weight of wholly aromatic polyamide fiber having a fineness of 1.5 denier and a fiber length of 47 mm (manufactured by DuPont, trade name "Kevlar (registered trademark))" and a fineness of 2 denier and a fiber length of 51 mm
In the same manner as in Example 1, a stretched polyphenylene sulfide fiber (manufactured by Toyobo Co., Ltd., trade name “Procon (registered trademark)” 2% by weight was used to form a web having a basis weight of 74 g / m ² and a melting temperature of 290 with a heating device. The temperature of the web raised to ℃ is 300 ℃ on the surface of the thermal calendar roller, and the linear pressure is 8kg.
Thermocompression bonding was performed at a pressure of / cm to obtain a heat resistant nonwoven fabric.

Example 3 99% by weight of wholly aromatic polyamide fiber having a fineness of 1.5 denier and a fiber length of 47 mm (trade name "Kevlar (registered trademark)" manufactured by DuPont), a fineness of 1.3 denier and a fiber length of 38
mm stretched polyester fiber 1% by weight was used to form a web having a basis weight of 77 g / m ^{2 in} the same manner as in Example 1, and the web heated to a melting temperature of 265 ° C. was heated by a heating device. Then, thermocompression bonding was performed at a linear pressure of 10 kg / cm to obtain a heat resistant nonwoven fabric.

As shown in Table 1, the heat-resistant non-woven fabrics of Examples 2 and 3 are excellent in impregnation property of heat-resistant insulating varnish, have high breakdown voltage, and have been subjected to the heat-resistant tensile strength deterioration test by the Arrhenius method. It is suitable as a heat-resistant electrical insulating sheet, as it is compatible with the H type specified by Further, it has a function excellent in electrical properties such as dielectric constant, dielectric loss tangent, and insulation resistance, and is particularly useful as a substrate for printed wiring.

Comparative Example 3 A paper-like nonwoven fabric of wholly aromatic polyamide fiber was obtained by a wet method. As shown in Table 1, the electrical properties are excellent, but the varnish impregnation property is remarkably poor.

[0026]

[Table 1] (Note) 1. All physical property values are average values in the vertical and horizontal directions. 2. Thickness and density are measured based on JIS-8118. 3. The strength and elongation test is measured according to JIS-P-8113. 4. The heat shrinkage rate and the weight loss rate are values when exposed to hot water of 300 ° C. for 30 minutes and returned to room temperature. 5. The air permeability is JIS using a Frazier type air permeability tester.
-L-1096 (Method 1990A). 6. The method of measuring castor oil impregnation is 18 x 18 mm.
Cut into 4 pieces each and heat the castor oil to 30 ± 0.5 ℃
To Drop the test piece with the front or back surface facing upward, parallel to the liquid surface of castor oil. Measure the time from the time it falls on the liquid surface to the time when the liquid completely penetrates and sinks, and read it in units of 1/10 seconds (the number of seconds of the average value of a total of 4 sheets, 2 on each of the front and back sides) . 7. The measuring method of silicon oil impregnation is 12.5 for the sample.
Cut into × 200mm, the viscosity of silicon (100cs,
The test piece is soaked in 6 mm in 1,000 cs and 10,000 cs, and the suction height (mm) after 1 hour is read. 8. JIS-for dielectric breakdown voltage, dielectric constant and dielectric loss tangent tests
It measures based on C-2111. 9. The insulation resistance (volume resistivity) is measured based on JIS-C-6521.

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[Procedure amendment]

[Submission date] August 25, 1993

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be amended] Claims

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[Claims]

[Procedure 3]

[Document name to be amended] Statement

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[0001]

The present invention relates to a wholly aromatic polyamide fibers as the main structure, relates polyester and / or polyphenylene Heat resistance not <br/> woven and manufacturing method thereof The fiber and molten component comprising sulfide, nonwoven fabric obtained by the present invention has excellent resistance to thermal insulating varnish impregnation, printed wiring substrate, heat-resistant electrically insulating sheet, heat resistance of the required filter, even necessary insulation heat resistance and flame retardancy It is used for a wide range of purposes such as heat insulation materials.

[Procedure amendment 4]

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[Correction target item name] 0008

[Correction method] Change

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On the other hand, polyphenylene sulfide resins are disclosed in Japanese Examined Patent Publication No. 52-80609 and Japanese Patent Laid-Open No. 58-31.
The fiberizing technique disclosed in Japanese Patent Application Laid-Open No. 112 etc. is known, and a short fiber felt by a heat-resistant needle punching method using polyphenylene sulfide fiber and JP-A-57-1 are used.
Such as long-fiber nonwoven fabric by spun bond method 6954 JP are known, both are those formed by mechanical entanglement, because there is no binding by thermal fusion, a long time load at high temperature In such cases, the shape retention is not sufficient. When the non-woven fabric is thermocompression-bonded in order to provide the heat-bonding bonding points, the whole is formed into a film, and the air permeability and the flexibility are greatly reduced.

[Procedure Amendment 5]

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[Correction method] Change

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Further, undrawn polyphenylene sulfide fiber having a high mixing ratio of 8 to 80% is used as a fusion component at a low temperature (183
The method of pressing at a high linear pressure (30 to 270 kg / cm) at ˜257 ° C.) is disclosed in JP-A-61-289162. In this case, a very large pressure is required, so that there is a mechanical restriction, and the air permeability and flexibility of the obtained nonwoven fabric are greatly reduced, so that the impregnation property of the heat resistant insulating varnish is reduced. In the case of using the application of the filter becomes poor passing over sexual liquid or gas.

[Procedure correction 6]

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[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is possible to use polyester fibers and / or polyphenylene sulfide fibers having an extremely low mixing ratio and by pressing at a low pressure. It has been found that a heat-resistant nonwoven fabric having breathability and flexibility can be obtained.

[Procedure Amendment 7]

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[Correction target item name] 0013

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[0013]

In order to solve the above problems, the production method according to the present invention is a method for producing a heat-resistant non-woven fabric excellent in heat-insulating varnish impregnation property by spot-bonding the intersections of the non-woven fabric constituent fibers. in the method, the nonwoven fabric constituting fibers as a main constituting the wholly aromatic polyamide fibers are fibers of polyester and / or polyphenylene sulfide, and said point bonding, polyester and / or polyphenylene sulfide fibers 3 wt 1 wt% or more of de % To form a web, which is lightly pressed and heat-treated by irradiation with far infrared rays, and then pressure-bonded for thermal bonding.

[Procedure Amendment 8]

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The heat-resistant non-woven fabric according to the present invention comprises wholly aromatic polyamide fibers as a main constituent, and polyester and / or
Or polyphenylene sulfide fiber cotton mixing with the intersection of the nonwoven fabric constituent fiber comprising less than 1 wt% to 3 wt%, characterized in that it is point bonded.

[Procedure Amendment 9]

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The wholly aromatic polyamide fibers used in the present invention include poly-m-phenylene isophthalamide fibers and modified products thereof, and poly-p-phenylene terephthalamide fibers and modified products thereof. Further, while being transported by the roller transporting means, a plurality of heating means are arranged to gradually heat the heating means. As a heating method of the heating means, the web is heated uniformly by the irradiation of far infrared rays, and the inner and outer layers are uniformly heated, so that the surface can be uniformly heated without burning. In the conventional heating method, heat is transmitted in sequence from the surface, whereas far infrared rays directly reach the object to be heated and generate heat without being absorbed by the medium such as the air layer. That is, the web can be spot-heated without raising the ambient temperature, and it is not necessary to seal the heating device. Therefore, the heating efficiency is high and the temperature control is extremely easy.

[Procedure Amendment 10]

[Document name to be amended] Statement

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The web gradually heated by far-infrared irradiation rises in temperature to a heat melting temperature of the thermoplastic resin used as an adhesive component, for example, 265 ° C. for polyester and 290 ° C. for polyphenylene sulfide, and then the heat is applied. It is pressed by a calendar roller. The pressure applied by the thermal calendar roller is in the range of 1 to 100 kg / cm of linear pressure. When the basis weight of the nonwoven fabric is less than 100 g / m ² , the linear pressure is 1 to 10 kg / cm, and 100 to 200 g / m ^2.
The linear pressure in the following cases is 20-50 kg / cm, 200 g /
When the pressure exceeds m ² , the linear pressure is 60 to 100 kg / cm. The surface temperature of the calender roller is preferably set slightly higher than the heat melting temperature in consideration of heat loss and the like.

[Procedure Amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0026

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[0026]

[Table 1] 1. All physical property values are average values in the vertical and horizontal directions. 2. Thickness and density are measured based on JIS-8118. 3. The strength and elongation test is measured according to JIS-P-8113. 4. The heat shrinkage rate and the weight loss rate are values when exposed to dry heat of 300 ° C. for 30 minutes and returned to room temperature. 5. The air permeability is JIS using a Frazier type air permeability tester.
-L-1096 (Method 1990A). 6. The method of measuring castor oil impregnation is 18 x 18 mm.
Cut into 4 pieces each and heat the castor oil to 30 ± 0.5 ℃
To Drop the test piece with the front or back surface facing upward, parallel to the liquid surface of castor oil. Measure the time from the time it falls on the liquid surface to the time when the liquid completely permeates and sinks, and read it in units of 1/10 seconds (the number of seconds of the average value of a total of 4 sheets on each of the front and back sides) . 7. The measuring method of silicon oil impregnation is 12.5 for the sample.
Cut into 200 mm, the viscosity of silicon is 100 cs,
The test piece is soaked in 6 mm in 1,000 cs and 10,000 cs, and the suction height (mm) after 1 hour is read. 8. JIS-for dielectric breakdown voltage, dielectric constant and dielectric loss tangent tests
It measures based on C-2111. 9. The insulation resistance (volume resistivity) is measured based on JIS-C-6521. ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] January 10, 1994

[Procedure Amendment 1]

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[Name of item to be corrected] 0024

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As shown in Table 1, the heat-resistant non-woven fabrics of Examples 2 and 3 are excellent in impregnation with a heat-resistant insulating varnish, have a high breakdown voltage, and have been subjected to the Arrhenius type heat-resistant tensile strength deterioration test.
And conforms to the H-class specified by the International Electrotechnical Commission
I think that the. Therefore, it is suitable as a heat resistant electrical insulating sheet. Further, it has a function excellent in electrical properties such as dielectric constant, dielectric loss tangent, and insulation resistance, and is particularly useful as a substrate for printed wiring.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

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[0026]

[Table 1] (Note) 1. All physical property values are average values in the vertical and horizontal directions. 2. Thickness and density are measured based on JIS-8118. 3. The strength and elongation test is measured according to JIS-P-8113. 4. The heat shrinkage rate and the weight loss rate are values when exposed to dry heat of 300 ° C. for 30 minutes and returned to room temperature. 5. The air permeability is JIS using a Frazier type air permeability tester.
-L-1096 (Method 1990A). 6. The method of measuring castor oil impregnation is 18 x 18 mm.
Cut into 4 pieces each and heat the castor oil to 30 ± 0.5 ℃
To Drop the test piece with the front or back surface facing upward, parallel to the liquid surface of castor oil. Measure the time from the time it falls on the liquid surface to the time when the liquid completely penetrates and sinks, and read it in units of 1/10 seconds (the number of seconds of the average value of a total of 4 sheets, 2 on each of the front and back sides) . 7. The measuring method of silicon oil impregnation is 12.5 for the sample.
Cut into × 200mm, the viscosity of silicon (100cs,
The test piece is soaked in 6 mm in 1,000 cs and 10,000 cs, and the suction height (mm) after 1 hour is read. 8. JIS-for dielectric breakdown voltage, dielectric constant and dielectric loss tangent tests
It measures based on C-2111. 9. The insulation resistance (volume resistivity) is measured based on JIS-C-6521.

Claims (4)

[Claims] 1. A method for producing a heat-resistant non-woven fabric excellent in impregnation with a heat-resistant insulating varnish by spot-bonding intersection points of non-woven fabric constituting fibers, wherein the non-woven fabric-constituting fibers mainly consist of wholly aromatic polyamide fibers, and polyester and And / or polyphenylene sulfide fibers, and the point bonding is a heat treatment by light pressure and far infrared irradiation by blending polyester and / or polyphenylene sulfide fibers in an amount of 1% by weight or more and less than 3% by weight. After that, the heat-resistant nonwoven fabric is formed by applying pressure and heat-bonding. 2. The thermal bonding of the non-woven fabric is gradually heated by far-infrared irradiation during transportation by a roller transporting means for applying light pressure, and after the temperature of the web is raised to the heat melting temperature of the thermoplastic resin, The method for producing a heat-resistant nonwoven fabric according to claim 1, wherein the pressure is applied at a linear pressure of 1 to 100 kg / cm. 3. The light pressure is a linear pressure of 0.2 to 0.8 kg.
It is / cm, The manufacturing method of the heat resistant nonwoven fabric of Claim 1 or 2 characterized by the above-mentioned. 4. A non-woven fabric comprising, as main constituent, wholly aromatic polyamide fibers and containing polyester and / or polyphenylene sulfide fibers in an amount of 1% by weight or more and less than 3% by weight, and the point of intersection of the fibers constituting the nonwoven fabric is point-bonded. Heat resistant non-woven fabric.