JPS6160865B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an aromatic polyamide having excellent stability against thermal oxidative decomposition, and more particularly to an aromatic polyamide composition containing an effective stabilizer against thermal oxidative decomposition. Substantially linear aromatic polyamides in which amide groups are directly bonded to aromatic groups (hereinafter referred to as aromatic polyamides) generally have high thermal stability and can be formed into fibers, papers, films, etc. It is used as a heat-resistant material. Aromatic polyamides are generally heated at 300℃ in air.
It is stable even if exposed to nearby high temperatures as long as the processing time is not long. However, if the processing time becomes longer even in the relatively low temperature range of around 200℃,
Because it undergoes thermal oxidative decomposition, its use as a heat-resistant material is limited. An example where such a phenomenon actually becomes a problem is when aromatic polyamide is incorporated into various electrical equipment as an electrical insulating material and used continuously for a long period of time. Recently, electrical equipment, especially motors and transformers, have become smaller and more sophisticated, and the temperature of the equipment during continuous operation can reach nearly 200°C. Generally, electrical equipment is required to have a very long service life, and it is not unusual for electrical equipment to be used for several years to more than ten years, especially in the field of heavy electrical equipment. During continuous use at high temperatures over such long periods of time, thermal oxidative decomposition of the insulating material progresses, albeit gradually, and the insulating structure is eventually destroyed. Heat resistance is required, and materials that are more stable against thermal oxidative decomposition are needed. In view of the above-mentioned current situation, the present inventors have conducted extensive research with the aim of improving the thermal oxidative decomposition properties of aromatic polyamides, and have found that by containing a specific amount of boron oxide, the thermal oxidative decomposition properties of aromatic polyamides can be improved. The inventors have discovered that an aromatic polyamide composition having excellent stability can be obtained, and have arrived at the present invention. That is, the present invention consists of (A) an aromatic polyamide and (B) an oxide of boron, and has a content of 0.01 to 10% relative to the component (A).
This is a heat-resistant aromatic polyamide composition containing % by weight of component (B). The compositions of the present invention have high stability against thermal oxidative degradation even when exposed to high temperatures in air, and can be used in the form of fibers, papers, films, and other articles, such as electrically insulating materials, etc. Suitable for use in fields exposed to The aromatic polyamide used in the present invention is a substantially linear polymer in which amide groups are directly bonded to aromatic groups. A portion of the hydrogens directly bonded to the aromatic ring of this aromatic polyamide may be substituted with a halogen, nitro group, sulfonate group, or low-temperature alkyl group, but the hydrogen bonded to the amide group must not be substituted. is desirable. Such an aromatic polyamide can be obtained, for example, by a bonding reaction between an aromatic diamine and an aromatic dicarboxylic acid dichloride or a condensation reaction of an aminobenzoyl halide salt, but the preferred production method for obtaining an aromatic polyamide is dimethylacetamide, N-methyl This is a polyamidation reaction by low-temperature solution polymerization in a lower alkylamide solvent such as pyrrolidone. Aromatic diamines suitable for producing aromatic polyamides include, for example, m-phenylene diamine,
4-methyl-m-phenylenediamine, 4-chloro-m-phenylenediamine, p-phenylenediamine and substituted derivatives thereof, 4,4'-diphenylenediamine, 4,4'-sulfonyldiphenyldiamine, etc. Examples of suitable aromatic dicarboxylic acid dichlorides include isophthaloyl chloride, 4-methyl-isophthaloyl chloride, 4-chloro-isophthaloyl chloride, terephthaloyl chloride, and substituted derivatives thereof. can give. Further, suitable aminobenzoyl halide salts include, for example, meta-aminobenzoyl chloride hydrochloride, para-aminobenzoyl chloride hydrochloride, and the like. Suitable aromatic polyamides used in the present invention include poly(m-phenylene isophthalamide), poly(m-phenylene/p-phenylene-isophthalamide) copolymer, poly(m-phenylene isophthalamide), poly(m-phenylene isophthalamide), poly(m-phenylene isophthalamide), and
-phenylene/p-phenylene-terephthalamide) copolymer, poly(p-phenylene terephthalamide), and the like. To produce molded articles from aromatic polyamide,
Conventionally known methods and devices can be employed.
For example, in the case of poly(m-phenylene isophthalamide), it is stabilized by performing low-temperature solution polymerization of m-phenylenediamine and isophthaloyl chloride in N-methylpyrrolidone, and then neutralizing it with calcium hydroxide. A polymer solution is obtained, and the solution is used as it is as a stock solution for molding, and fibers are manufactured by dry spinning or wet spinning. Further, a film is manufactured by a casting method. Also,
Fibrids are produced by fibrid molding. Furthermore, paper is manufactured using flock and fibrids obtained by cutting the fibers into short pieces. In the case of aromatic polyamides that are difficult to dissolve in organic solvent systems, various molded products can be produced by dissolving them in concentrated sulfuric acid.
To produce moldings from aromatic polyamides, 96
The logarithmic viscosity was determined from the value measured at 25℃ of a solution of 0.5g of polymer dissolved in 100ml of wt% sulfuric acid.
It is preferred to use polymers of 0.6 to 6.0, preferably 1.0 to 3.0. In the present invention, boron oxide is used as a stabilizer. A particularly useful boron oxide is boron oxide. These oxides of boron as stabilizers may be mixed with the aromatic polyamide by any method. In addition, this mixing may be performed so that these stabilizers may be uniformly dispersed in the aromatic polyamide composition, or may be attached to the surface of the molded product or locally dispersed non-uniformly. However, it is desirable that these stabilizers are uniformly dispersed and mixed in the aromatic polyamide composition.
Furthermore, it is desirable that the powder be in the form of a fine powder with a diameter of about 10 μm or less and uniformly dispersed and mixed. Specific methods for mixing boron oxide and aromatic polyamide include dissolving the boron oxide in a stock solution or melt for producing molded products, or oxidizing finely ground boron. After the materials are dispersed and mixed, they can be molded. Alternatively, a solution or dispersion in which a boron oxide is dissolved or dispersed may be applied to the molded article by dipping or spraying, and then the molded article may be dried. Alternatively, a boron oxide is dissolved or dispersed in a solvent capable of swelling and dissolving aromatic polyamide, and the solution or dispersion is impregnated into the molded product under conditions such that the surface of the molded product swells. It may be dried. The amount of boron oxide to have sufficient effect as a stabilizer is from 0.01 to 10% based on the weight of the aromatic polyamide. If the amount of boron oxide is too small, sufficient effects cannot be obtained, while if it is too large, thermal oxidative decomposition will be accelerated. Particularly favorable results are obtained with amounts ranging from 0.5 to 5%. Further, in carrying out the present invention, there is no problem in using, for example, hindered phenol compounds, amine compounds, and other various conventionally known stabilizers. The present invention will be explained in more detail below by giving examples. Note that "parts" in the examples mean "parts by weight." Example 1, Comparative Example 1 A solution of 108 parts of m-phenylenediamine dissolved in 1000 parts of N-methylpyrrolidone was cooled to 0°C, and then 203 parts of isophthalic acid chloride was added and reacted for 1 hour. After the reaction was completed, 74 parts of calcium hydroxide was added to neutralize the hydrochloric acid produced by polymerization to obtain a transparent and viscous stock solution. [This stock solution (A)
]. (A) contained 17.2% by weight of poly(m-phenylene isophthalamide). A film with a thickness of 30 μm was obtained from (A) by the dry method described in JP-A-52-42560. On the other hand, boron oxide powder was added to (A) in an amount of 1.0% by weight based on the polymer in (A) to obtain a stock solution [this stock solution is referred to as (B)]. From the thus obtained (B), a thickness of 30 mm was obtained by the same dry method as above.
A film of μ was obtained. 10 pieces of each film obtained as above
Cut it into a size of cm x 10 cm and put it in a weighing jar.
Heat treatment was performed in an air furnace maintained at 300°C.
In addition, each film was cut into a size of 15 cm x 15 cm, fixed on a frame, and heat-treated in an air oven maintained at approximately 300°C. After the number of days shown in Table 1 had passed, the weighing bottle and frame were removed and the weight and tensile strength of the film were measured. The results are shown in Table-1. Next, (A) and (B) were prepared at 55°C containing 100% glycerin as described in JP-A-50-130849.
The fibers were extruded from the die into a coagulation bath, coagulated in the coagulation bath, and then subjected to wet heat stretching in hot water to obtain fibers. A few pieces of each of the obtained fibers were cut out every 1 m and placed in an air oven maintained at approximately 300°C for heat treatment.After the number of days shown in Table 1 had elapsed, the fibers were taken out and their weight and tensile strength were measured. The results are in the table.
Shown in 1. Next, N-methylpyrrolidone was added to (A) and (B) so that the content of poly(m-phenylene isophthalamide) was 8% by weight, and the mixture was sufficiently stirred. These stock solutions were added to a fruit juice mixer containing glycerin as described in JP-A-53-51252, and the mixture was stirred and mixed to obtain fibrids. 40 parts by weight of a floc obtained by cutting the previously spun fibers into short pieces and 60 parts by weight of this fibrid were dispersed in water and then made into paper to obtain paper. Cut this paper into 10cm x 10cm pieces and make approximately 300 pieces.
Heat treatment was performed in an air oven kept at ℃.
After the number of days shown in , the weight and tensile strength were measured. The results are shown in Table-1.

[Table] Example 2 Films, fibers, and paper were obtained in the same manner as in Example 1 except that the amount of boron oxide added was changed to 5.0% by weight, and tested in the same manner as in Example 1. Table of results-2
Shown below.

[Table] Example 3 Films, fibers, and paper were obtained in the same manner as in Example 1 using (A) in Example 1. A solution prepared by dispersing boron oxide in water was sprayed onto this molded product and dried to obtain a molded product having a boron oxide content of 7.5% by weight based on the polymer. The weight and tensile strength of this product were measured in the same manner as in Example 1. The results are shown in Table-3.

[Table] Example 4, Comparative Example 2 A solution of 92 parts of m-phenylenediamine and 16 parts of p-phenylenediamine dissolved in 1400 parts of N-methylpyrrolidone was cooled to 0°C, and then 203 parts of terephthalic acid chloride was added. The mixture was added and reacted for 1 hour. After the reaction was completed, 74 parts of calcium hydroxide was added to neutralize the hydrochloric acid produced by polymerization to obtain a transparent and viscous raw material [this stock solution is referred to as (C)]. This (C) contained 12.3% by weight of poly(m-phenylene/p-phenylene terephthalamide) copolymer. next
Boron oxide powder was added to (C) in an amount of 10.0% by weight based on the polymer in (C) [this stock solution is referred to as (D)]. Using these (C) and (D), a film with a thickness of 25 μm was obtained by the dry method in the same manner as in Example 1. The obtained film was subjected to the same test as in Example 1.
The results are shown in Table 4.

[Table] Example 5 A solution of 76 parts of m-phenylenediamine and 32 parts of p-phenylenediamine dissolved in 1000 parts of N-methylpyrrolidone was cooled to 0°C, and 203 parts of isophthalic acid chloride was added thereto for 1 hour. Made it react. After the reaction was completed, 74 parts of calcium hydroxide was added to neutralize the hydrochloric acid produced by polymerization to obtain a transparent and viscous stock solution (this stock solution is referred to as (E)). This (E) contained 17.2% by weight of poly(m-phenylene/p-phenylene isophthalamide) copolymer. next
Boron oxide powder was added to (E) in an amount of 3.0% by weight based on the polymer in (E) [this stock solution is referred to as (F)]. Using these (E) and (F), a film with a thickness of 25μ was obtained by the dry method in the same manner as in Example 1, and then in Example 1.
The test was conducted in the same manner. Table of results-4
Shown below.

Claims (1)

[Claims] 1 Consisting of (A) a substantially linear aromatic polyamide in which amide groups are directly bonded to aromatic groups, and (B) an oxide of boron, 0.01 to 10% by weight of ( B)
A heat-resistant aromatic polyamide composition containing the following ingredients.