JPS6099056A - Production of heat resistant high strength nonwoven fabric - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a nonwoven fabric having excellent strength, heat resistance, and dimensional stability.

Conventionally, non-woven fabrics include interlining, disposable clothing 2 synthetic leather base 4',
Clothing materials such as A, wall decorations, interior decoration items such as curtains, etc.
Felt, filters, insulation and sound absorbing materials.

It is widely used in industrial materials such as battery separators, and its applications have recently become increasingly expanded and diversified. Special IF RP J41 reinforcement cloth for clothing, etc., especially thin layer but with great heat resistance.

It is now being used in fields that require strength and dimensional stability.

In general, nonwoven fabrics are made of synthetic fibers:, semi-synthetic fibers, natural fibers, unwoven fibers,
+, inorganic g! 8 fibers, etc., depending on the purpose, and the web consisting of these short filaments 11 is interlaced by needle punching, the action of an adhesive or the constituent fiber bath) R7, etc. Combining methods are often used. The formation of the above-mentioned web is usually carried out by carding or air-laying, and the fibers used therein are crimped or bent to a certain degree in advance to improve workability. In addition, in the web immediately after carding, that is, the parallel web, ()η synthetic fibers: are arranged with considerable directionality, so the nonwoven fabric obtained therefrom is a nonwoven fabric from a non-oriented, so-called random web. In comparison, the strength in the orientation axis direction is large. However, even in parallel webs, it cannot be said that the fibers are completely parallel to each other due to oscillation of the fibers and residual crimping during the manufacturing process, and therefore, the nonwoven fabric obtained from it The strength of the constituent fibers was not sufficiently realized.

On the other hand, from a material perspective, synthetic wire parts that are commonly used, such as polyethylene terephthalate.

Fibers made of nylon 66, nylon 6, polyolefin, etc. have melting points of about 270°C or lower, and nonwoven fabrics made from them soften and shrink at about 120°C to 200°C, lose strength, and become unusable. .Also,
Inorganic fibers, such as glass fibers, ceramic fibers, silica fibers, and silicon carbide fibers.

Silicon nitride fibers, etc. are generally rigid and have low refractive strength, so they encounter difficulties in the carding process.
It is not only extremely difficult to produce a small thin sheet material with "" by a dry method, but also it is generally expensive except for the glass fiber thread 11, which is not preferred in practice. Additionally, natural fibers are severely limited in their use due to their strength and dimensional stability.

Furthermore, in recent years, aromatic polyamide fibers (aramid fibers) and carbon fibers have been developed and put into practical use as heat-resistant, high-strength fibers. For example, heat-resistant nonwoven fabrics made of aramid fibers and polyester fibers have already been developed. It is publicly known. However, its strength and dimensional stability are
Due to the inherent structural properties of the fabric, polyester fibers w, 10
There is no discernible difference from nonwoven fabric made of 0%, the breaking length is only about less than 5,000 m, and the breaking elongation is about 20% or more. is far from what it should be suitable for a specific use.

Against this current technical background, the present inventors have developed electrical insulating AA materials, flexible copper-clad laminated board (00L) base fabrics, belt base materials, reinforcing fabrics for multilayer FRP such as bulletproof clothing, etc. The present invention was arrived at as a result of intensive research aimed at economically advantageously providing a thin sheet material that is particularly advantageous in terms of heat resistance, strength, dimensional stability, and flexibility. It is.

That is, the moisture-resistant high-strength nonwoven fabric according to the present invention has stable heat-resistant fibers and stable thermo-NJ plastic fibers having a cohesive temperature lower than the heat deformation temperature of the heat-resistant fibers.
~9 years old. The heat-resistant fibers are uniformly mixed in a weight ratio of The thermoplastic fibers are at least partially adhered to form a matrix integral with the skeleton 4A of No. 1111, and the sheet paulownia material is at least about a,ooo
It is characterized by having a breaking length of m and a breaking elongation of at most about 5%, and further comprising such a sheet ion material and its H
The lifting platform of a resin-treated fiber structure consisting of a fiber resin finishing agent of 5 to 50% of the total fiber weight attached to the surface of the woven fibers has a tearing length of at least about 12,000, n, and at most about It is characterized by having a breaking elongation of 3%.

In addition, the above-mentioned sheet paulownia material is made of stable heat-resistant fiber,
Stable thermoplastic fibers having a sticking temperature below the heat distortion temperature of the heat-resistant fibers are heated at 4° to overnight. Preferably 2*o
A parallel web formed by uniformly mixing the thermoplastic fibers at a weight ratio of ~8*o is heated to a temperature higher than the adhesiveness of the thermoplastic fibers, and at the same time the web is heated to a temperature of 5 to 100% in the -axial direction, preferably 1
The heat-resistant fibers are stretched by 5 to 35% and thus bonded and held by the thermoplastic fibers in a softened or molten state, and the heat-resistant fibers are crimped.

The thermoplastic fibers are oriented in the stretching direction while being stretched, and then cooled and solidified so that the thermoplastic fibers are at least partially adhered to each other and integrally envelop the stretched and long-oriented heat-resistant fibers. The above-mentioned resin-treated tJA fiber structure, which can be obtained by a manufacturing method characterized by forming a sheet-like matrix and has further improved physical properties, is obtained by subjecting the sheet paulownia material to delicate resin processing. It can be manufactured by a manufacturing method characterized by applying resin in an amount of 5 to 50% (in terms of solid content) of the total fiber weight.

The heat-resistant tJAill applied to the present invention is preferably an organic or inorganic fiber having a heat deformation humidity of at least about 300°C, and also has a tensile strength of at least about 10'7 since it becomes the skeleton material of the nonwoven fabric of the present invention. It is preferable to have the following.

Here, the heat deformation temperature refers to the temperature at which the material forming the vA string undergoes substantial thermal contraction, plastic flow, or thermal decomposition. etc., but below the specific melting point 2
It is said that the temperature is about 0 to 80°C.

Examples of such heat-resistant fibers include aramid fibers such as polyparaphenylenetere-7-talamide and polymetaphenylene isophthalamide, and carbon fibers.

Mention may be made of phenolic fibers and inorganic fibers such as metal fibers, glass fibers, ceramic fibers, silicon carbide fibers, silicon nitride fibers, among others, with particular emphasis on price, availability and other properties such as folding resistance, workability, etc. From this point of view, polyparaphenylene terephthalamide and carbon fibers are particularly advantageous.

Such heat-resistant fibers have high heat resistance and high strength 9 of the nonwoven fabric of the present invention.
It serves as a framework material to maintain a high level of dimensional stability.

In addition, the thermoplastic fiber used in the present invention has a viscosity of
7AM degree is required to be lower than the heat distortion temperature of the above-mentioned heat-resistant fiber, for example, polyolefin taAI such as polyethylene, polypropylene [i: polyvinyl chloride,
Vinyl fibers such as polyvinylidene chloride and polyacrylonitrile; polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate,
Polyesters such as polyethylene-P, P'-diphenyldicarboxylate; nylon 61, nylon 66, nylon 6101, nylon 7, nylon 210. nylon 4
6. Nylon 56. Examples include m fibers formed from polyamides such as nylon 58, and polyester fibers and polyamide fibers are particularly preferred.Among them, when aramid fibers are selected as the heat-resistant fibers, BoIJ x stell,
In particular, it is most suitable to use polyethylene terephthalate fibers in combination. These fiber-forming polycondensates may contain other copolymer components or additives. Such thermal IJ plastic fibers are preferably applied in the state of undrawn fibers so as not to cause extreme shrinkage when forming an IJ sock by the heat treatment described below.

Both the above-mentioned heat-resistant fiber and thermoplastic fiber are used in stable form, and the fiber length is preferably about 15 to loo+nm. These fibers may be used alone or in a mixture of two or more, but the mixing ratio of the heat-resistant fibers and the thermoplastic fibers is 1O/6O to 9% in weight hk ratio. It is preferably in the range of 24 to 85% 4o. If the blending ratio falls outside the above range and the amount of heat-resistant fiber becomes too small,
The strength and elongation characteristics and thermal stability of the obtained sheet material will be impaired, and if it becomes too large, thermoplastic fibers will form (see below).
This is not acceptable because the IJ sock structure becomes too coarse, the enveloping force of the heat-resistant fibers is poor, and the tensile strength of the sheet material in the width direction becomes extremely low.

The above-mentioned fibers are crimped or bent using a gear crimper or stuffer box, or in the case of Funshugate fibers, crimps are made apparent by releasing internal strain, and then the blending ratio within the above range is applied. The fibers are then put into a mixer such as an opener mixer, where they are sufficiently mixed and defibrated to form a mixed fleece.

The mixed fleece is further fed to a carding machine such as a roller card or a flat card, and is carded in a conventional manner to obtain a mesh size of about 60 or less, preferably 542 to 3.
While adjusting to 0 consultation, it will be made into a parallel sea bream.

There is a tendency for parallel web webs to be extremely small, especially in multi-layer web applications such as flexible OOL applications, and for the intended use of the present invention, sheets exceeding the above-mentioned values are required. Trading is not suitable because flexibility may be impaired.

The parallel web made in this way has a long shape, and the constituent fibers are oriented along the longitudinal axis, but the degree of torsion is low and there are crimps, bends, etc. Confounding and aggregating due to

The thus-produced parallel web can be immediately subjected to the heating and stretching process described below to form the nonwoven fabric of the present invention, but it can be prepared by heat treatment or heating [1: treatment] in advance.
After forming an intermediate nonwoven fabric in which heat-resistant fibers are integrally wrapped in a matrix formed by fusion of heat-of-plastic fibers, heating and stretching treatment is performed to ensure stable process 1 quality. Most preferred above. Such an intermediate nonwoven fabric can be obtained by laminating a plurality of parallel webs as necessary and heat-treating the web at a temperature higher than the bonding temperature of the thermoplastic fibers and lower than the heat deformation humidity of the heat-resistant fibers. Further, if necessary, the heat treatment may be performed under the action of pressure in the thickness direction of the parallel web, and the pressure is closely related to the set temperature, heating time, and other conditions, but it is approximately 0.5η to 150Ω. Preferably about 50 cm
A range of 100 mm is preferable, and if the above pressure range is not reached, the thermoplastic fibers may not be sufficiently fused and the IJ sock may not be formed satisfactorily and the stretching orientation described below may not be fully achieved. On the other hand, if the amount exceeds the above range, the intermediate nonwoven fabric will not lose its original properties, and in severe cases may be damaged.

The heating time depends on the pressure, temperature, web weight,
Although it varies depending on the diameter of the thermoplastic fiber, about 0.5 seconds to 1
It is appropriately selected within the range of 0 seconds. The heat treatment is carried out using a hot flue or, in the case of combined use of pressure, a known and commonly used machine such as a two or three roll calender or a hot press machine, but a continuous process using a calender machine is particularly advantageous.

By such heat treatment, the thermoplastic fibers in the parallel web are heated to a temperature higher than their bonding temperature, causing plastic deformation or plastic flow, and the fibers are at least partially bonded at the mutually contacting portions to form a sheet-like matrix. In this case, if the content of thermoplastic fibers is large, it will become an IJ sock with a substantially continuous dense structure, and even if the content is relatively small, especially if unstretched fibers are used, stretched fibers will be formed. The result is a porous or reticulated matrix in which the bonded parts are uniformly distributed throughout, without causing extreme heat shrinkage as with fibers.

Since the thermoplastic fibers were selected to have an adhesion temperature lower than the heat deformation temperature of the heat-resistant bond 111, they are not substantially altered or deformed in the web even by the heat treatment described above.

However, due to carding, the heat-resistant fibers are oriented to some extent along a single axis in the spreading direction of the web, that is, along the longitudinal axis in the case of a long web, but the degree of parallelism is still low, and crimping, The fibers remain bent and are integrally adhesively enveloped in a matrix formed by mutual fusion of thermoplastic fibers.

The parallel web is subjected to a heating stretching process with or without the above-mentioned heating treatment or heating and pressure treatment. The hot stretching step is carried out using a known hot stretching device comprising two sets of nip rolls or apron rolls and heating means provided between them.

The heating means may be any known and commonly used means, such as bringing the web into contact with a rod-shaped heater placed horizontally across the web's traveling direction, or using a plate heater placed horizontally along the web path. It is important that the capacity n1 is sufficient to heat the web therein above the sticking temperature of the thermoplastic fibers, ie, to the softening melting temperature.

In addition, the stretching is 5 to 100%, preferably 15 to 35%.
The stretching ratio is as follows. If the stretching ratio is less than the above range, the crimp, bending, elongation and orientation of the fibers will be insufficient, while if it is too much, uneven thickness will occur, and in extreme cases there is a risk of breakage. Not possible. Through this heated stretching process, the thermoplastic fibers in the parallel web or intermediate nonwoven fabric are softened and melted, and their adhesive strength causes them to fuse together to form a viscous matrix, while at the same time providing heat-resistant properties.
.

When the heat-resistant fibers are adhesively held together and stretched in that state, the crimps, bends, etc. are removed by stretching while the heat-resistant fibers are held in the viscous matrix, and the heat-resistant fibers become 1 (i-linear) and are further stretched. The thermoplastic fibers are oriented with a high degree of orientation in the direction and become the skeleton side.After that, when appropriately cooled, the adhesive force of the thermoplastic fibers is lost and solidified into the above-mentioned M) IJ Lux sheet form, which is substantially linear and highly oriented. The sheet material of the present invention, ie, the heat-resistant high-strength nonwoven fabric, is obtained in which the skeleton side made of the heat-resistant fibers is integrally wrapped.

The sheet phased sheet obtained as described above has excellent properties and is useful as it is, but it can be further strengthened by further heating and pressurizing if necessary. This heating and pressure treatment is carried out in a manner similar to the heating and pressure treatment applied before stretching as described above.

The sheet material in the present invention is made up of a sheet-like matrix and a substantially linear and highly oriented skeleton integrally adhesively enveloped therein, as is clear from the above description. acts to support the load acting on the sheet material and provide the sheet material with high tensile strength, low elongation at break, high heat resistance and low thermal shrinkage. -1 The sheet material according to the present invention has a basis weight of 6 o's or less,
Since it is preferably formed into an extremely thin layer of 30 trigrams, it exhibits good flexibility even if most of the fibers are fused together. In addition, if high-strength aramid fibers are used as the heat-resistant fibers that form the framework material, and polyester fibers are used as the matrix, the two types of combination have poor affinity for each other, so the relationship between the framework material and the matrix is caused by mechanical stress. It peels off easily and becomes loose, so that the flexibility of the sheet material is not impaired.

The sheet material thus obtained exhibits a breaking length of at least about 8,00 ohm and an elongation at break of no more than about 5%, measured along its longitudinal axis. In other words, since the framework material is already substantially linear and highly oriented, when an elongation force is applied, the elongation associated with the increase in stress is extremely small, and it exhibits excellent dimensional stability. . As described above, in the nonwoven fabric according to the present invention, the heat-resistant fibers that are its constituent fibers form a linear and highly oriented skeleton material, and the sheet-like matrix formed from the thermoplastic fibers mixed with the heat-resistant fibers serves as a skeleton material. Because it is made by integrally bonding and enveloping the fibers, it has the high tensile strength derived from the linear skeleton material and the distorted heat resistance inherent to the fiber, and is flexible because it is formed into a thin layer. In addition, when a rigid material is selected as the frame material, it has excellent bending durability because it is enveloped and protected by IJ Lux, and also has good τ method stability, symbolized by a small elongation at break. In order to further improve the above-mentioned favorable properties of the nonwoven fabric of the present invention, the weight of the sheet material f'F is 5 to 50% (
- Resin processing agent for fibers corresponding to (in terms of shape), preferably a resin whose main ingredient is at least one organic polymer compound selected from the group consisting of melamine resin, phenol resin, and epoxy resin. It is extremely effective to form a resin-processed fiber structure in which the processing agent is applied to the surface of the fibers constituting the sheet material.

In addition, by selecting an appropriate type of resin processing depending on the use of the nonwoven fabric of the present invention, such a resin-processed fiber structure can increase its affinity with the resin during FRP production and produce high-quality FR.
P can be produced.

For example, phenol resin processing is used for reinforcing phenolic resin moldings, epoxy resin processing is used for reinforcing epoxy resin moldings, and melamine resin processing is used for polyamide and polyimide melamine resin moldings. good. These resin treatments are carried out using known and commonly used methods that are normally applied to textile products.
If it is less than the above range, the effect of the resin processing will not be realized substantially, while if it is too large, the nonwoven fabric will be coarse and hard9 and its flexibility will be reduced, which is not preferable.

By applying the above resin processing, the nonwoven fabric of the present invention can be
At least 7 and about 12.
It has a tear UIt length of QOoff+ and a breaking elongation of about 3%, and its tensile strength and dimensional stability are further increased.

The thin-layer nonwoven fabric of the present invention obtained as described above has properties such as excellent heat resistance, high strength, low elongation, one-dimensional stability, bending durability, and flexibility, so it can be used as an electrically insulating thin nonwoven fabric. Impregnated base material, flexible aaL, multilayer OOL base fabric, special PR, P reinforcing fabric, belt base material, magnet wire, taping, mica-lined sleeves! It is particularly effective against i'ii kidnapping.

Examples of the present invention are shown below.

Example 1 Single fiber fineness 1.5d, average fiber length 38M! vL polyparaphenylene terephthalamide fiber with a deformation temperature (carbonization temperature) of 450°C (manufactured by DuPont, USA, product name: “Kevlar”)
) 60 parts by weight of stable and 41. Fineness 5. Od
, an undrawn polyethylene terephthalate fiber stable with an average fiber length of 38 fil and a melting point temperature of 265°C (Toshi Co., Ltd.)
After mixing and fibrillating 40 parts by weight of Lyester l'T. An intermediate nonwoven fabric was produced by passing it through a roll calender machine and heating and pressurizing it at 200°C and 80°C.The polyparaphenylene terephthalamide fibers in the intermediate nonwoven fabric maintained their crimps and were lowered in the longitudinal direction of the nonwoven fabric. A sheet-like material formed by fusing polyethylene terephthalate fibers with some degree of orientation)
It was buried integrally in IJ Lux. This product was designated as control product (1).

The control product (1) was an epoxy resin (manufactured by Tobu Kasei Co., Ltd.).

The non-woven material I'I was processed by epoxy resin processing using a conventional method using the product (trade name "Evotonito") to deposit about 28% of the epoxy resin on the fiber surface on average on the fiber surface.
i was used as a control product (2).

Next, the comparative product (1) in Item 1''1j was continuously stretched by 30% between two sets of nip rolls arranged in series while being brought into contact with a rod-shaped heater heated to 260°C. Thereafter, the obtained paulownia wood sheet was heated to 210°C.

The nonwoven fabric was treated again using a roll calender at a temperature and pressure of 80°C (up to 80°C), and the obtained nonwoven fabric was designated as product (1) of the present invention.

The product (1) of the present invention is subjected to the same epoxy resin processing as described above, and about 28% of the epoxy resin of the total fiber set fft is adhered to the fiber surface on average, and the resulting resin-treated fiber 1 "structure of the present invention is Product (2).

The physical properties of these control products and the product of the present invention were compared in Example 2. As the heat-resistant fiber 1F, the same polybara phenylene terephthalamide ta fiber stave/l/f as in Example 1 was used.
As a thermoplastic delicate, single fiber fineness 5.5d, uniform fiber breakdown 1
Using a 4-point WIM 225°C nylon 6-fiber stable with a length of 40 TnIn (bias cut +), the mixing ratio was varied to obtain a 30 f! /n? created a parallel web.

They were heated to 205℃ and 50℃ using a two-roll calender machine.
This was heated and pressed under the conditions of η to obtain an intermediate nonwoven fabric, which was further subjected to heat stretching treatment in the same manner as in Example 1 except that the heating temperature was 215° C. to form a sheet of paulownia wood.

The above-mentioned sheet kA material is treated with methyl methacrylate-butadiene copolymer latex (MBR), which is commonly used as a rubber binder. MBR of ('=
I made him wear J.

Table 2 shows the breaking length and breaking elongation of the obtained nonwoven fabric, which were measured in the fiber orientation direction (longitudinal direction) and in the direction crossing it (width direction).

(Margins below) Table 2 As is clear from Table 2, if the mixing ratio of heat-resistant fibers and thermoplastic fibers is too small, the tensile strength in the longitudinal direction of the nonwoven fabric will be insufficient, and if it is too large, the tensile strength in the width direction will be insufficient. The tensile strength of the mixture becomes extremely small, which is unacceptable in any case, and the above mixing weight ratio is 10/9 to 9 years. , preferably a seat. It can be seen that it is within the range of ~8*o.

Example 3 Polymetaphenylene isophthalamide fiber stabilizer (manufactured by DuPont, USA, trade name 1 Nomex) with a single fiber fineness of 1.7 cl, average fiber length of 42 M, and heat deformation temperature of 350° C. was used with 65 claws. Fiber fineness 7.5d, average yarn 11
44 tnm in length + 35 parts by weight of tactical polypropylene fiber stable with a melting point temperature of 170°C.
0t/H? A parallel web was formed. Various nonwoven fabrics were produced using the same stretching apparatus as in Example 1 except that the temperature of the heater was 150° C., and by varying the stretching ratio.

The results are shown in Table 3.

Table 3 From the results shown in Table 3, if the stretching ratio is less than 5%, the elongation at break will be excessive, and the tearing length will also be small, making it unsuitable as a reinforcing base fabric.On the other hand, if the stretching ratio exceeds 100%, It is understood that this method is unsuitable because the stretched bed is large and can lead to breakage.

Claims (1)

[Claims] (1) A staple-shaped heat-resistant fiber and a staple-shaped hot-open plastic fiber having a sticking temperature lower than the heat deformation temperature of the heat-resistant fiber (1% 0 to 9%). Parallel web f made of homogeneous fibers with a weight ratio of: thermoplastic fibers that are heated to a temperature higher than the adhesive temperature of the thermoplastic fibers and stretched 5 to 100% in a uniaxial direction, thus softening or melting the fibers. The heat-resistant fibers bonded and held by the thermoplastic fibers are crimped and bent and oriented in the stretching direction while being stretched, and then cooled and solidified so that all of the thermoplastic fibers are at least partially bonded to each other and A method for producing a heat-resistant, high-strength nonwoven fabric characterized by forming a sheet-like matrix formed by integrally enveloping elongated and oriented heat-resistant fibers. 2. The method for producing a heat-resistant, high-strength nonwoven fabric according to claim 1, wherein the heat-resistant fiber is an aramid fiber. 8. A method for producing a heat-resistant, high-strength nonwoven fabric in which aramid fibers are made of polyparaphenylenetere. 4. Claim 1 in which the heat-resistant fiber is carbon fiber
A method for producing a heat-resistant, high-strength nonwoven fabric as described in Section 1. 5. The method for producing a heat-resistant high-strength nonwoven fabric according to any one of claims 1 to 4, wherein the thermoplastic fiber is a polyester fiber. 6. The method for producing a heat-resistant, high-strength nonwoven fabric according to claim 5, wherein the polyester fiber is a polyethylene terephthalate fiber. 7. A method for producing a nonwoven fabric as claimed in the claims, wherein the thermoplastic fibers are undrawn fibers. 8. A method for producing a heat-resistant high-strength nonwoven fabric according to any one of claims 1 to 7, wherein the stretching is carried out at a stretching ratio of 15 to 35%. 9. Production of the heat-resistant high-strength nonwoven fabric according to any one of claims 1 to 8, which is a mixed type of heat-resistant fiber and thermoplastic fiber; Law. 10. Stable heat-resistant fibers and stable thermoplastic fibers having a sticking temperature lower than the heat deformation temperature of the heat-resistant fibers are uniformly mixed at a weight ratio of 1% to 9%. The parallel web made of the thermoplastic fibers is heated to a temperature higher than the adhesive temperature of the thermoplastic fibers and stretched 5 to 100% in the uniaxial direction, and the heat-resistant fibers bonded and held by the thermoplastic fibers in a softened or molten state are wound. The thermoplastic fibers are oriented in the stretching direction while being stretched and bent, and then cooled and solidified so that the thermoplastic fibers are at least partially adhered to the phase U and integrally envelop the stretch-oriented heat-resistant fibers. A process for producing a heat-resistant, high-strength nonwoven fabric, which is characterized by forming a sheet-like matrix consisting of a fiber, and then subjecting it to a delicate resin treatment to provide resin in an amount of 5 to 50% (in terms of solid content) of the total fiber weight. 11 A patent claim in which the resin processing for fibers comprises forming on the fiber surface a film of at least one organic polymer compound selected from the group consisting of melamine resin, phenol resin, unsaturated polyester resin, polyimide resin, and epoxy resin. A method for producing a heat-resistant high-strength nonwoven fabric according to claim 10. 12. A method for producing a heat-resistant high-strength nonwoven fabric according to claim 10 or 11, wherein the heat-resistant fiber is an aramid fiber. A method for producing a heat-resistant high-strength nonwoven fabric according to claim 12, wherein the aramid fiber is polyparaphenylene terephthalamide fiber. 14. Feature 111: Claims 10 to 14, wherein the heat-resistant wire 41I' is carbon fiber. 15. The heat-resistant high-strength nonwoven fabric according to any one of claims 10 to 14, wherein the thermoplastic fiber is a polyester fiber. A method for producing a nonwoven fabric. 16. A method for producing a heat-resistant high-strength nonwoven fabric according to any one of claims 10 to 15, wherein the thermoplastic fibers are unstretched and delicate. 17. Stretching is 15 to 35%. A method for producing a heat-resistant high-strength nonwoven fabric according to any one of claims 10 to 16, which is carried out at a stretching ratio of 18. The mixed ifk ratio of heat-resistant fibers and thermoplastic fibers is 1°. A method for producing a heat-resistant, high-strength nonwoven fabric according to any one of claims 10 to 17.