JPS6024877B2 - sheet - Google Patents

Description

[Detailed description of the invention] The present invention relates to sheets.

More specifically, the present invention relates to a sheet formed by mixing short fibers with pulp particles mainly made of aromatic polyamide or copolyamide having a specific structure, and pressurizing and heating the mixture. Conventionally, natural pulp is the most well-known pulp used for paper.

However, the above natural pulp has poor heat resistance. In recent years, pulps made of synthetic polymers have been known to eliminate these drawbacks.

For example, Hakama Publication No. 35-111851 describes a pulp-like object made of a synthetic polymer, and Japanese Patent Publication No. 38-1139
No. 122 describes a method for producing a sheet consisting of the above-mentioned freshly formed pulp-like material and fibers. However, sheets made of the pulp-like material described above still have poor mechanical properties such as heat resistance and strength. In order to eliminate such drawbacks, the present inventors have conducted extensive research and found that by making paper by mixing short fibers with pulp particles mainly made of aromatic polyamide or copolyamide having a specific structure and heating the mixture under pressure, the present inventors have achieved heat resistance, electrical insulation properties, A sheet with excellent mechanical properties such as flame retardancy and strength could be obtained. That is, the present invention is directed to '1' represented by the following general formula H--A [wherein Y is -○- or -S-].

] Diamine repeating unit (11A) represented by the following general formula (11B) -NH-Ar, -NH-...
(11B) [2' The following general formula (b) -CO -Ar2-CO-... (0) [In the formula, A may be the same as or different from Ar, and have the same definition as ~, It is the basis.

), and the number of moles of the diamine repeating units (1-A) and (1-B) is the same as the dicarboxylic acid repeating unit (0). substantially equal to the number of moles of and
An aromatic polyamide characterized in that the diamine repeating unit (11A) contains 7.5 to 50 mol% of the total repeating units at a concentration of 2 to 2% by weight,
Tetramethylurea, hexamethylphosphoramide, N,
N-dimethylacetamide, N,N-dimethylformamide, N-methylpyrrolidone-2, N-methylpiveridone-2, N,N dimethylethyleneurea, N,N,N',
N'-tetramethylmalonic acid amide, N-methylcaprolactam, N-acetylpyrrolidone, N,N-dimethylpropionic acid amide, N,N-dimethylisobutyropionic acid amide, N,N-dimethylisobutylamide, N −
Dissolved in an organic solvent selected from a mixed system of methylformamide, N,N-dimethylpropylene urea and mola in the presence of a halide or hydrogen halogen of Group 1 or Group 2 of the Mendelev Periodic Table, if necessary. This sheet is obtained by mixing pulp particles and short fibers obtained by introducing a precipitant into a precipitant, which is rapidly passing through a solution, and heating the mixture under pressure.

When producing the pulp particles used in the present invention, a method can be applied in which the polymer solution is introduced into a precipitant of a high-speed Tohai, and simultaneously subjected to a shearing or beating action while removing the solvent to form pulp particles. As the polymer solution, the solution obtained by polymerizing the raw materials may be used as is, or the polymer obtained by polymerization may be isolated, and then a solution dissolved in a solvent for the polymer may be used. Good too. Further, as the polymerization solution, a mixed solution obtained by adding and mixing inorganic filler fine particles described below to the solution may be used, or the filler may be added when the polymer is dissolved in a solvent. It is also possible to mix such inorganic filler fine particles with raw materials and solvents and to defecate the polymerized liquid. When producing the aromatic polyamide used in the present invention, polymerization methods normally used for producing polyamides, such as melt polymerization, phase polymerization, interfacial polymerization, and solution polymerization, can be used.

Among these, interfacial polymerization and solution polymerization are preferred, and solution polymerization is more preferred. * When producing the aromatic polyamide solution used in the present invention, the aromatic polyamide may be redissolved in the solvent system, but in the case of a solution polymerization method, the aromatic polyamide is produced in a solution, It is useful as it is or by diluting or concentrating it to obtain the aromatic polyamide solution used in the present invention.

The details of the method for producing the aromatic polyamide used in the present invention will be described below. The aromatic polyamide used in the present invention is at least one of the aromatic diamines (1-A) represented by the following general formula (1-A).
The species is represented by the following general formula (1-A) (HX)n-day2N-Ar,
-NH2(HX)m. ．． ．． (1-A) In the formula, Ar is a phenylene group, a naphthylene group, or a biphenylene group in which the bonding chain extends in the coaxial direction or in the parallel axis direction, or Y in the following formula
2 is the same as the definition of Y above, and may be the same as or different from Y.

It is a group represented by

At least one aromatic diamine (1-B) represented by
Species and '2' The following general formula■ In the formula, ~2 is the same as the definition of ~, above, and mountain 2 and ~,
may be the same or different.

At least one aromatic dicarboxylic acid halide represented by
) is substantially equal to the number of moles of the aromatic dicarboxylic acid halide [21], and the number of moles of the aromatic diamine (1
-A) in an amount of 7.5 to 50 mol% of the amount of the diamines (1-A) and (1-) and the dicarboxylic acid halide [21].
They can be produced by reacting with each other using such amounts.

As x in the above formulas (1-A), (1-B) and '2'', a chlorine atom is particularly easily available and suitable. The preferred aromatic diamines of the above formulas (1-A) and (1-B) and the aromatic dicarboxylic acid halide of the above formula (2) are the same as the preferred repeating units corresponding to these mentioned above. do.

In addition, it is preferable that n and m in the formulas (1-A) and (1-B) are both 0 or 1. In the solution polymerization method, the above-mentioned at least two diamines and at least one dicarboxylic acid are reacted using substantially equal moles of the diamine and the dicarboxylic acid, so that at least a portion of the highly polymerized aromatic polyamide to be produced is The aromatic copolyamide used in the present invention can be produced by carrying out the reaction in an organic solvent in which the copolyamide can be dissolved, optionally in the presence of an acid acceptor, at a temperature in the range of -20 DEG C. to 100 qo.

In this case, it is preferable to carry out the above reaction in the presence of a halide of a metal of Groups 1 and 2 of the Mendelev Periodic Table or a hydrogen halide. It acts as a solubilization aid for aromatic copolyamides that produce halides of these metals and hydrogen halides. An amide solvent is suitable as the organic solvent, and preferable examples of such an amide solvent include tetramethylurea, hexamethylphosphoramide, N,N-dimethylacetamide, N,
N-dimethylformamide, N-methylpyrrolidone-2
, N-methylpiberidone-2, N,N-dimethylethyleneurea, N,N,N',N'-tetramethylmalonic acid amide, N-methylcaprolactam, N-acetylpyrrolidone, N,N'- Diethylacetamide, N-ethylpyrrolidone-2, N,N-dimethylpropionic acid amide,
Examples include N,N-dimethylisobutyramide, N-methylformamide, N,N'-dimethylpropylene urea, and mixtures thereof.

Among these, in particular, N-methylpyrrolidone-2, hexamethylphosphoramide, N,N-dimethylacetamide,
Preference is given to N,N-dimethylformamide and mixtures thereof. As a suitable polymerization operation, for example, the above formula (1-
After dissolving at least two diamines or hydrohalide salts thereof of A) and (1-B) in the amide solvent, the dicarboxylic acid halide, particularly dicarboxylic acid dichloride, is added to this solution while stirring vigorously. . Depending on the compound used, in some cases the viscosity increases rapidly after addition, and in other cases the viscosity increases slowly, but the polymerization reaction is substantially completed after 2 hours at the most. At this time, the amide solvent also acts as an acid acceptor for hydrohalides, such as hydrohalides, which are separated by the above reaction. The temperature of the reaction is -20
~100°C is preferable, more preferably -5~70q
It is o. In such a solution polymerization reaction, the concentration of monomers to be charged is such that the viscosity of the obtained polymerization solution and/or the viscosity of the obtained polymerization solution is appropriate.The concentration of monomers to be charged is determined by the species and proportion of selected monomers and the type of solvent. Although it varies depending on the reaction temperature and the like and can be determined through a series of experiments, it is generally preferably 2 to 3% by weight, and more preferably 4 to 2% by weight.

During polymerization, it is preferable to add the above-mentioned solubilizing agent for the aromatic copolyamide to be produced to the polymerization reaction solution before, during and/or after the polymerization. I have already mentioned such solubilizing agents, such as lithium chloride,
Calcium chloride and hydrogen chloride are particularly preferred. Alternatively, an alkaline metal compound such as lithium hydroxide, lithium carbonate, calcium hydroxide, calcium oxide, calcium carbonate, lithium hydroxide, or calcium hydride may be added to the polymerization reaction solution before, during, or after the polymerization reaction. For example, the metal compound acts as a neutralizing agent for the polymerization reaction mixture, and the salts of the metal produced as a result of the neutralization reaction also act as a solubilizing agent for the aromatic polyamide produced. The aromatic polyamide solution (polymerization solution) obtained by the solution polymerization method described above can be used as the solution used in the present invention as it is after polymerization.D Such a polymerization solution may not contain the above-mentioned metal salt. However, those containing it are preferable.

If necessary, a chain terminator can be added as another additive to the polymerization solution, and a suitable chain terminator is a compound having only one group that reacts with an amide group or a haloformyl group. . Further, in the present invention, the solution obtained by the above polymerization reaction is mixed with water etc., the precipitate is taken, washed and dried, and the obtained polymer is again dissolved in a solvent to obtain the solution used in the present invention. It can be done.

The aromatic polyamide polymer used in the present invention is a polymer that provides pulp particles with excellent solubility, heat resistance, electrical insulation properties, and flame retardancy.

Conventionally, it has been known that polyamide polymers obtained only from compounds represented by the above formula (1-B) and formula '2}' provide fibers with excellent mechanical properties. Since coalescence does not have sufficient solubility in organic solvents, it is not easy to obtain a highly concentrated solution suitable for molding, and it is necessary to use solvents such as sulfuric acid, which are highly corrosive and difficult to handle, and are difficult to recover from aqueous solutions. No. The polymerization solution obtained by the solution polymerization method may be used as it is in the present invention, or not only the solution polymerization method but also a conventionally known melt polymerization method, solid phase polymerization method, oligomer polymerization method, interfacial polymerization method, or The copolyamide formed by the combination thereof is once separated and recovered from the polymerization reaction mixture, and the copolyamide is dissolved again in an appropriate solvent to prepare the solution used in the present invention. As mentioned above, those with a value of 0.5 to 7, particularly 0.8 to 40, are suitable. By using aromatic poly-IJ amide having such an intrinsic viscosity, it is not only possible to easily form a highly concentrated polymer solution that can be formed into a Q-form, but also to produce pulp particles with excellent impregnating properties and paper-making properties. .

Even if the above-mentioned solution manufacturing method is adopted, the solution of the aromatic copolyamide used in the present invention is such that the aromatic polyamide is mixed with tetramethylurea or hexamethylphosphoramide at a concentration of 2 to 2% by weight. , N,N-dimethylacetamide, N,N'-dimethylformamide, N-
Methylpyrrolidone-2, N-methylpiveridone-2, N
, N-dimethylethylene urea, N,N,N',N'-tetramethylmalonic acid amide, N-methyl cuff. Rolactam, N-acetylpyrrolidine, N,N-diethylacetamide, N-ethylpyrrolidone-2,N,N-diethylpropionic acid amide, N,N-dimethylisobutyramide, N-methylformamide, N,N -dimethylpropylene urea and a mixture thereof, in the presence of a halide or hydrogen halide of a metal of Group 1 or Group 2 of the Medeleph Periodic Table, if necessary. It is advantageous to use The solution used in the present invention contains 0.2 to 1% by weight of the total dope as a solubilizing agent for the aromatic copolyamide of the present invention, preferably 0.2 to 1% by weight of the total dope.
It is advantageous to add from 5 to 5% by weight of halides of metals from groups 1 or 2 of the Mendelev Periodic Table or hydrogen halides.

Addition of such a solubilization aid not only improves the solubility of the aromatic copolyamide in the organic solvent, but also increases the stability of high-temperature solutions. As the solubilizing aid, lithium chloride, calcium chloride, and magnesium bromide are particularly preferably used.

On the other hand, for the purpose of lowering the viscosity of the solution to an appropriate value, it is effective to contain hydrogen halide, particularly preferably hydrogen chloride. When producing a grade yarn stock solution by the redissolution method, it is preferable to grind the aromatic polyamide into sufficiently fine particles in advance, and it is preferable to use particles with a degree of crystallinity of 4. Further, it is advantageous to sufficiently enrich the aromatic polyamide with the organic solvent at a low temperature of, for example, 0° C. or lower, especially 110° C. or lower, and then mix it at a high temperature of about 50 to 100° C. to form a solution. It is. Pulp particles of the aromatic polyamide can be produced by introducing the above solution into a precipitant which is being rapidly discharged through a suitable opening. The precipitant used in the production of the pulp particles used in the present invention is preferably a liquid or solution that is miscible with the solvent of the polymer solution but is a non-solvent for the polymer and inorganic filler fine particles.

Such precipitating agents will vary depending on the type of solvent used. When using an organic solvent as a solvent, use water alone, glycerin,
It may be an aqueous solution of ethylene glycol, glycerin-water temperature compound, ether, etc., or the above-mentioned organic solvent, or an aqueous solution in which one or more salts represented by MXn are dissolved. good. Here, M is Li, Na,
K, Mg, Ca, Sr, Ba, Sn, Zn, AI or N
In i, X is CI, N03, Br, CH3COO or SCN
n is an integer from 1 to 4.

Examples of such salts include calcium chloride, lithium chloride, aluminum chloride, and the like. Calcium chloride
Water-based precipitants are preferred because they are easy to handle and inexpensive.

When an inorganic solvent is used as the solvent, the precipitant is preferably water alone or an aqueous solution of the inorganic solvent. Depending on the composition of the aromatic polyamide, or if the solution contains metal halides and/or hydrogen halides, depending on their type and content, lithium chloride or sodium chloride may be dissolved in water or water containing the organic solvent. , at least one inorganic salt selected from the group consisting of calcium chloride, magnesium chloride, zinc chloride, strontium chloride, aluminum chloride, stannic chloride, nickel chloride, calcium bromide, calcium nitrate, zinc nitrate, and aluminum nitrate. Preferably, a precipitant containing a precipitant is used.
Examples of the inorganic filler fine particles that may be contained in the polymer solution when producing the pulp particles used in the present invention include mica, asbestos, glass fiber, glass flakes, quartz powder, talc, alumina, calcium sulfate, calcium carbonate, and kaolin clay. , silica, feldspar powder, magnesium carbonate, magnesium oxide, etc.

In the present invention, an excellent sheet can be obtained by mixing pulp particles with short fibers and making paper.

It is preferable to make paper from the pulp particles and short fibers by a wet process using a fourdrinier type or cylinder type paper making machine, as in conventional paper making from natural pulp. The short fibers can be the same type or different type of the aromatic polyamide polymer constituting the pulp particles, but short fibers made of an inorganic compound may also be used. . In the present invention, it is preferable that the short fibers used in paper making together with the pulp are heat-resistant fibers, and usually have a twill degree of 0.
．． The fiber length is preferably 5 to 10 denier and 1 to 2 denier.

Various polymers can be used to form such heat-resistant fibers, and examples include the following fibers. 1. The short fiber aromatic polyamide made of aromatic polyamide is a condensation polyamide of a highly active derivative of a dicarboxylic acid having an aromatic ring, preferably an acid halide, and a diamiso having an aromatic ring.

For example, dicarboxylic acids include terephthalic acid and isophthalic acid, and diamines include metaphenylene diamine and 4.4
It may be a homopolymer consisting of a type of dicarboxylic acid or a type of diamine using ``-diaminophenyl ether, 4, page aminophenyl methane, xylylene diamine, N-methyl-paraphenylene diamine, etc.; A copolymer consisting of two or more compounds of either one or both of the acid component and the diamine component may be used.

Typical examples include polymetaphenylene isophthalamide, polymethaxylene terephthalamide, a copolymer of metaphenylene diamine, isophthalic acid, and terephthalic acid, and polyN-methylparaphenylene terephthalamide.

This polyamide is obtained by activating and condensing an aminocarboxylic acid having an aromatic ring.

For example, the aminocarboxylic acid may be a homopolymer of only one type of aminocarboxylic acid such as para- or meta-amidobenzoic acid or para-aminomethylbenzoic acid, or a copolymer of two or more types of aminocarboxylic acids.

A typical example is a condensate of para-aminobenzoic acid.

Furthermore, a polyamide obtained by polymerizing the above polymer.

A typical example is a polyamide made by condensing three components: metaphenylenediamine, isophthalic acid chloride, para-aminobenzoic acid chloride, and hydrochloride.

can be mentioned.

The aromatic polyamide suitable for the present invention is (11
In the general formula and/or formula, R, , R2, and R3 are the same or different hydrogen atoms or alkyl groups having 5 or less carbon atoms, and ~,, ~2, and 3
are the same or different groups represented by the general formula -1.

[Here, Y is -○- or -S-, and A represents a 1,4-phenylene group or a 4,4-biphenylene group in which both bond chains extend in the same or parallel axes.

], and at least 7 of the total amount of Ar, , A et al., Ar3 in the repeating unit
．． An aromatic polyamide in which 5 mol% is (Y is the same as above).

'21 A carbocyclic aromatic homo- or copolyamide in which the linking chains extend from each aromatic trench in a coaxial or parallel axial direction.

Among the above-mentioned carbocyclic aromatic homo- or copolyamides, the carbocyclic aromatic homo- or copolyamide in which the bond chains extend coaxially or in parallel is an aromatic ring in which the bond chains extend in the coaxial direction, such as 1 , 4-phenylene, 4,4'-piphenylene, etc. These aromatic rings may have substituents, but the substituents must not cause undesirable reactions during polymerization and processing steps. No.

Examples of such substituents include halogen groups (e.g. C
I, Br, F) Lower alkyl groups (eg, methyl, ethyl, isopropyl, n-propyl), lower alkoxy groups (eg, methoxy, ethoxy), cyano groups, acetyl groups, and nitro groups.

The above polymer chain consists of an amide bond (one COHN) and an aromatic ring, but in addition to this, for example, the aromatic polyamide bond may not extend coaxially or parallel to the aromatic ring. (e.g. meta-orientation)
Polymers containing about 10 mol% of bonds other than amide bonds, such as urea bonds, ester bonds, and hydrazide bonds, can also be used.

Examples of such aromatic polyamides include the following.

Poly(P-benzamide) Poly(P-phenylene terephthalamide) Poly(2-chloroP-phenylene terephthalamide) Poly(P-phenylene-2,6-naphthalene dicarboxylic acid amide) Poly(2,6-dichloro-P-phenylene-2, 6-naphthalene dicarboxylic acid amide) poly(P,P'-phenylenebenzamide) poly(1,5 naphthylene terephthalamide) regular aromatic copolyamide (e.g. P,P'-
copolymer of diaminobenzanilide terephthalamide) random copolyamide (e.g. P-benzamide/P
- Phenylene terephthalamide 50/50, etc.

) These polymers are used as a homopolymer alone, a copolymer alone, a mixture of homopolymers, a mixture of a homopolymer and a copolymer, and a mixture of copolymers. The above-mentioned polymers can be produced by a method using a low-temperature solution polycondensation method of an aromatic dicarboxylic acid halide and an aromatic diamine, or a method using a hydrohalide salt of an aromatic aminocarboxylic acid halide.
It can be synthesized by the method shown below. 2 Short fibers made of inorganic compounds Examples of short fibers made of inorganic compounds include glass fibers, asbestos fibers, rock wool, Shisuren cotton,
Dissolved silica fiber, glassy silica fiber, Setomono fiber,
There are inorganic fibers such as kaolin fiber, bauxite fiber, khanite fiber, boron fiber, potassium titanate fiber, magnesium fiber, and whiskers such as alumina and silicon nitride.

Such short fibers can be used alone or in combination of two or more.

The blending ratio of pulp particles in the sheet is preferably 10 to 9% by weight. If the content of pulp particles is less than 1% by weight, the tensile strength, elongation, and dielectric breakdown voltage will be poor, which is not preferable.
On the other hand, if it exceeds 9% by weight, the tensile strength and elongation will be poor, which is not preferable. After the sheet obtained as described above is dried, it can be heated under pressure using a hot press or a hot roll to impart excellent physical properties such as strength and elongation.

The appropriate pressure temperature is 200 to 40,000. The pressure to be applied is preferably 200k9/carp or less. The sheet according to the present invention can be used as a diaphragm for electroacoustic transducer equipment by taking advantage of its excellent heat resistance, mechanical properties such as strength, and electrical insulation properties.
It is applied to structural materials, building materials, electrical insulation paper, etc.

The method for measuring the main characteristic values of the present invention will be described below.

Logarithmic viscosity: Measured in concentrated sulfuric acid at a concentration of 0.5/100' at 3000.

Tensile strength: Measured according to JISP8113 method, k9
/Represented by legs.

Tensile elongation: Measured by the method of JISP8132 and expressed in %.

Dielectric breakdown voltage: Measured using AC voltage according to the method of JISC2111 and expressed in KV/sail.

Oxygen index: In accordance with ASTM D2863-70, the oxygen percentage was determined when the flame continued to burn for about 1.5 degrees by upward ignition with downward support.

Example 1 (Manufacture of pulp) 3.48% of 3,4-diami/phenyl ether and 1.8% of paraphenylenediamine were mixed with N-methylpyrrolidone.
A powder of 7.07 g of terephthalic acid chloride was dissolved in 2.150 g of the solution and added at room temperature under high speed.

After polymerizing at 60°C for 3 hours, 1.95 g of calcium oxide was added to neutralize the by-product hydrochloric acid, and N-methylpyrrolidone-2
The mixture was heated for about 200 hours, and then lit for 2 hours at 50 o'clock to obtain a solution with a polymer concentration of about 2.5%.

The logarithmic viscosity of this polymer was 2.25. The resulting polymer solution was introduced as a trickle stream using a funnel into a 2% by weight N-methylpyrrolidone-400% aqueous solution in a home blender which had been running at high speed for about 50 minutes.
(Manufacture of sheet) After thoroughly washing the pulp particles with water, the pulp particles were dispersed in water, and a wet warp and hot-stretched fiber (warpth: 1. red e, fiber length: 5 side) was prepared from the N-methylpyrrolidone-2 solution of the polymer. ) was mixed with a dispersion in water and paper was made at various blending ratios.

After drying, the sheet was hot pressed at 340° C. and 100k9/m to obtain a sheet. Table 1 shows the physical properties of the sheet.
Table 1: Shameful. Case 1 is a case where the blending ratio of pulp in the sheet is too low, which is undesirable because the tensile strength, elongation, and dielectric breakdown voltage are poor.

No. 2 to 4 are within the scope of the present invention, and both tensile strength and elongation and dielectric breakdown voltage are excellent. No. No. 5 is a case where the blending ratio of pulp in the sheet is too high, and the dielectric breakdown voltage is good, but the tensile strength is poor. Earth. 6 is a comparative example and shows the physical properties of commercially available Nox Vapor Type 410 (registered trademark of DuPont) made of polymetaphenylene sophthalamide, which has good tensile elongation and dielectric breakdown voltage, but poor tensile strength. snake. It is inferior to 3. Example 2 In place of the polymer in Example 1, 7.57 g of 3,4'-diaminophenyl thioether and 1.62 g of paraphenyl diamine were added to 15 g of N,N-dimethylacetamide.
After dissolving the powder and cooling it to 0°C, add 10.15 g of terephthalic acid dichloride powder while stirring vigorously, polymerize at 30 g, add 3.70 g of calcium hydroxide, and stir. The mixture was further diluted by adding 100' of N,N-dimethylacetamide, and continued to be heated at 5,000 for about 3 hours.

The solution obtained by this operation was introduced into a 3% by weight aqueous solution of N,N-dimethylacetamide in a homomixer running at high speed to obtain pulp particles. After thoroughly washing the pulp particles, Example 1 was prepared. Paper was made by mixing it with short fibers made of the same polymer as in No. 3. After drying such a sheet, 34
A sheet was obtained by hot pressing at 0qo and 100k9/m.
The sheet had the following physical properties.

Tensile strength 9k9/Yanagi2 tensile elongation
3% breakdown voltage
2 Female V/Rib Example 3 The same method as in Example 1 was used except that the polymer solution in Example 1 was mixed so that the content of muscovite in the final pulp obtained was 65% by weight. Pulp was obtained by precipitation.

After washing the pulp with water, the ship of Example 1. The physical properties of a sheet made with the same composition as No. 3 and pressed at 100k9/m at 360:00 were as follows. Tensile strength 8.5k9/side 2 tensile elongation
3% breakdown voltage
1 Peach V/side Example 4 Example 1 Shame. When poly P-phenylene phthalamide short fibers (fiber 1.e, fiber length 5) were used as the short fibers in Example 3, the physical properties of the sheet were as follows.

Tensile strength: 11kg/side 2 Tensile elongation: 5% Breakdown voltage
It was a secondary V/rib.

Example 5 Example INo. When glass fibers with a diameter of 10 strands and a fiber length of 4 were used as the short fibers in Example 3, the physical properties of the sheet were as follows.

Tensile strength 6k9/Yanagi2 tensile elongation
2% breakdown voltage
2 Dish V/Skin Example 6 Example IM. 3
When the sheet was subjected to heating deterioration in air at 260°C for 10 hours, the results shown in Table 2 were obtained.

Table 2 Center rudder. No. 3 has excellent tensile strength and tensile elongation retention after heat deterioration.

On the other hand, the comparative example Nomex Vapor Type 4
No. 10 (registered trademark of DuPont) is inferior in retention of tensile elongation after heat deterioration. Example 7 Example INo. Regarding seat 3, Toyo Rika Kogyo O
Using an N-1 type flammability tester, the oxygen index was determined according to the method of ASTM D2863-70, and it was 28.
Flame retardancy was extremely good.

Claims (1)

[Claims] 1 General formula (I-A) ▲There are numerical formulas, chemical formulas, tables, etc.▼ [In the formula, Y_1 is -O- or -S-. ] A diamine repeating unit (I-A) represented by
General formula (I-B) -NH-Ar_1-NH-(I-B) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Diamine repeating unit (I-B) represented by
2) General formula (II) -CO-Ar_2-CO-...(II) [In the formula, Ar_2 may be the same as or different from Ar_1, and is a group with the same definition as Ar_1. ], and the number of moles of the diamine repeating units (IA) and I-B) is equal to the dicarboxylic acid repeating unit (II). An aromatic polyamide having a concentration of 2 to 20% by weight, which is substantially equal to the number of moles of the diamine repeating unit (I-A) and containing 7.5 to 50 mol% of the total repeating units, A sheet obtained by mixing short fibers with pulp particles obtained by introducing a solution dissolved in an amide solvent into a precipitant that is being stirred at high speed, and then pressurizing and heating the mixture. 2 The amide solvent is tetramethylurea, hexamethylphosphoramide, N,N'-dimethylacetamide,
N,N-dimethylformamide, N-methyl-pyrrolidone-2, N-methylpiperidone-2, N,N diethyleneurea, N,N,N',N'tetramethylmalonic acid amide, N-methylcabrolactam, N -acetylpyrrolidine, N,N-diethylacetamide, N-ethylperolidone-2, N,N-dimethylpropionic acid amide, N,
N-dimethylisobutylopionamide, N,N-dimethylisobutylamide, N-methylformamide, N,
The sheet according to claim 1, wherein the organic solvent is selected from N'-dimethylpropylene urea and a mixture thereof. 3. The sheet according to claim 2, wherein the amide solvent contains a halide or hydrogen halide of a metal of Group 1 or Group 2 of the Mendelev Periodic Table. 4 -Ar in the general formulas (I-B) and (II)
The sheet according to claim 1, 2 or 3, wherein _1- and -Ar_2- are each paraphenylene groups.