JPH0331732B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a novel aromatic polyamide in which oxidation-induced adhesion is prevented by terminal treatment of the soluble heat-resistant polyamide. Prior Art Aromatic polyamide has a molecular structure in which rigid aromatic rings and intermolecular cohesive forces are connected by strong amide groups, so it has a high soft point and thermal decomposition point. In addition to heat resistance, it also has excellent chemical and physical properties such as chemical resistance, mechanical properties, and electrical properties. Therefore, aromatic polyamides are extremely useful materials, particularly for use in heat-resistant fibers, films, paints, adhesives, molded products, and the like. Aramids such as Kevlar generally have the above-mentioned characteristics, and are insoluble in most solvents and have difficulty in processability. Therefore, one way to overcome the problem of processability is to make it soluble. Korsiatsk et al., Journal of Macromol.Sci.
Rev. Macromol.Chem.Cll, 45, 1974) reports on soluble polyamides, but does not mention the prevention of oxidation and the prevention of discoloration thereby. Problems to be Solved by the Invention Although aromatic polyamides, which generally have great rigidity and high symmetry, have excellent mechanical properties, they have a high melting point and are close to the decomposition point, making it difficult to melt mold. be. Furthermore, it has the disadvantage of poor solubility, making it difficult to use as an industrial material. Poly(p-phenylene terephthalamide), a typical aromatic polyamide, can be dissolved in concentrated sulfuric acid, lithium chloride, calcium chloride, etc. in hexamethylphosphorylamide or N-methylpyrrolidone, but it still has poor solubility. The drawback is that it is difficult to use as a solution because of its low concentration. Furthermore, amino groups directly connected to aromatic rings are highly susceptible to oxidation; for example, it is well known that even though aniline is colorless and transparent during distillation, it is rapidly oxidized and its color progresses. Also in the present invention, the 9,9-bis(4-aminophenyl)fluorenes used as raw materials have two aniline groups, that is, amino groups directly connected to the aromatic ring. Therefore, coloring occurs during the polymerization reaction, and even after polymer formation, the terminal amino groups are colored due to oxidation by light, heat, air, etc. That is, polyamide without end treatment gradually becomes more colored. The object of the present invention is to provide a heat-resistant polyamide with improved solubility and coloration. Means for Solving the Problems That is, the present invention provides an organic polymer having an amide bond at the terminal represented by the general formula () R ¹ CO(-NH-Y-NH-X)-nNH -Y-NH-COR ¹ Molecular polyamide, dimethylacetamide
Intrinsic viscosity (ηinh) of at least 0.30 dl/g measured at 30°C in a solution of 0.5 g of the above polyamide in 100 ml
Soluble heat-resistant polyamide with [However, R ¹ represents an alkyl group or an aromatic group, and Y is

[Formula] (where R ² is either H, CH ₃ or C ₂ H ₅ ), and X is

[Formula] and

At least one member of the group consisting of [Formula], where n indicates the number of repeating units. ]. As the aromatic polyamide,

【formula】

【formula】

[Formula] Contains at least one of the structural units (a), (b) and (c) in the chain, and as can be seen from the general formula () above,
This is a polyamide obtained by reacting the component represented by (a) with approximately equimolar amounts of the components represented by (b) and (c). In addition, in the present invention, in order to convert the terminals into amide, the reaction is carried out with slightly more component (a) so that the ends of the polyamide before terminal treatment become component (a). That is. In the present invention, polyamides include 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(3-
Polymerization using methyl-4-aminophenyl) fluorene or 9,9-bis(3-ethyl-4-aminophenyl) fluorene and either or both of terephthalic acid chloride and isophthalic acid chloride in a solvent such as dimethylacetamide under cooling. It can be manufactured by performing the following steps. In the polymerization, coloring during the polymerization reaction can be suppressed by using 9,9-bis(4-aminophenyl)fluorenes with good monomer purity and adding acid chloride as a solid powder. The terminal amino group in the obtained polyamide is treated by using an alkyl chloride or acyl chloride to introduce an alkyl group, an aromatic group, or a group of a derivative thereof as R ¹ at the polyamide terminal. For example, an acetyl group, a benzoyl group, etc. are introduced, and R ¹ in the general formula is a methyl group, an ethyl group,
Preferably, it is a phenyl group. Due to the end treatment of polyamide, polymer solutions can be stored for long periods of time without turning yellow-brown, and films and fibers made from this polymer also remain white and transparent, with almost no coloration observed over time. I can't. Furthermore, coloring due to air oxidation is also prevented from increasing. The intrinsic viscosity (ηinh) of the polyamide of the present invention is at least 0.30 dl/g, preferably 0.35 dl/g
That's all. When the intrinsic viscosity is less than 0.30 dl/g, the degree of polymerization is low and moldability and processability are poor. That is, it is difficult to form into a film or the like, and its physical properties such as tensile strength are sufficient. In addition, the intrinsic viscosity is dimethylacetamide 100
It was determined by measuring at 30°C using a solution in which 0.5g of the polyamide of the present invention was dissolved in ml. The heat resistance of the obtained polyamide is such that the glass transition temperature is 280°C to 420°C, preferably 300 to 400°C, and the decomposition temperature is 420°C or higher in air, preferably 440°C.
℃ or higher, and has sufficient heat resistance for practical use. The polyamide of the present invention is soluble in pyridine, m-cresol, o-chlorophenol N-methylpyrrolidone (NMP), dimethylacetamide (DMAC), etc., and is insoluble in chloroform, methylene chloride, toluene, and benzene. Note that by changing the ratio of the components (b) and (c), the heat resistance and solubility will change. As can be seen from the examples described below, the higher the ratio of isophthalic acid to terephthalic acid, the better the solubility. By increasing the proportion of terephthalic acid, N-
Solubility in methylpyrrolidone and dimethylacetamide is decreased. Furthermore, the glass transition temperature tends to be higher when the proportion of terephthalic acid is higher. According to the present invention, it is possible to provide a polyamide with good mechanical properties and electrical insulation properties, and the obtained polyamide is suitable for the field of electrical insulation. Further, the polyamide of the present invention can be made into a thin film with a thickness of about 0.005 to 0.20 mm without any coloring by a conventionally known method, and can be used for various purposes. A more detailed explanation will be given below based on examples. Example 1 In a three-necked flask (1) equipped with a stirrer,
34.8g of 9-bis(4-aminophenyl)fluorene (mp233-235℃) and triethylamine
20.2g was dissolved in 500g of dimethylacetamide. While maintaining the bath temperature at 5 to 10°C, a mixture of 10.15 g of terephthalic acid chloride and 10.15 g of isophthalic acid chloride was gradually added as a solid. After 3 hours, 1.1 g of benzoyl chloride was added, and after further stirring for 2 hours, triethylamine hydrochloride was filtered off to obtain a polyamide solution. When benzoyl chloride is not added, coloration begins several hours after the reaction, but with this method, there was almost no coloration and it could be stored for a long time. The physical properties of the obtained polyamide are as follows:
The intrinsic viscosity was 0.41 dl/g, the glass transition temperature was 320°C, and the decomposition temperature was 470°C in air. The polyamide solution was cast onto a glass plate and dried under reduced pressure to obtain a polyamide film. The tensile strength of this film is 9.0Kgf/mm ² and the tensile modulus is 570.
It was Kgf/ ^mm2 . This polymer was dissolved in N-methylpyrrolidone, dimethylacetamide, pyridine, o-chlorophenol, and m-cresol. The intrinsic viscosity (ηinh) was measured by dissolving 0.5 g of polyamide in 100 ml of dimethylacetamide and using an Ostwald viscometer in a constant temperature water bath at 30°C. Example 2 Using the same apparatus as in Example 1, 9,9-bis(4-aminophenyl)fluorene (mp232-234
℃) was dissolved in 200 ml of dimethylacetamide, and further 4.04 g of triethylamine was added.
The mixture was kept at 5° C. and 4.06 g of isophthalic acid chloride was gradually added thereto. After stirring for 3 hours, benzoyl chloride
1 g was added and further stirred for 2 hours. This polyamide solution was poured into water, filtered, washed with water and methanol, and dried to obtain a white powder polymer. The powdered polymer was dissolved in dimethylacetamide and cast onto a glass plate to produce a film. The tensile strength of the obtained film was 8.5Kgf/mm ² ,
The tensile modulus was 560 Kgf/mm ² . In this example, isophthalic acid chloride was replaced with terephthalic acid chloride, and the same procedure was carried out. The results are summarized in Table 1 together with the results of Example 3. Example 3 In the same manner as in Example 2, 6.96 g of 9,9-bis(4-aminophenyl)fluorene (mp 232-234°C) was dissolved in 200 ml of dimethylacetamide, and 4.04 g of triethylamine was added. The mixture was kept at 5° C. and a mixture of 2.03 g of terephthalic acid chloride and 2.03 g of isophthalic acid chloride was added, and after stirring for 3 hours, 1 g of benzoyl chloride was added and stirred for 2 hours. After filtering the polymer solution, it was poured into methanol, and the polymer was filtered, further washed with methanol, and dried. The obtained polymer was dissolved in dimethylacetamide and cast onto a glass plate to produce a film. No coloration was observed on the film, and no coloration was observed even after it was left in the air for one month. The film had a tensile strength of 11.9 Kgf/mm ² and a tensile modulus of 590 Kgf/mm ² . Other characteristics include:
Volume resistivity 5.4×10 ¹⁵ Ωcm (23℃), 3.7×10 ⁷ Ωcm
(200℃), dielectric constant 4.02, dielectric loss tangent 0.054 (1MHz),
The dielectric breakdown strength was 88 kv/mm, the total light transmittance was 90.3%, and the yellowness was 4.1%.

[Table] Note that commercially available Kevlar (registered trademark) was insoluble in all of the above solvents. Effects of the Invention The aromatic polyamide according to the present invention has excellent heat resistance, solubility, and processability, and is not colored, so it is preferable and useful when used as a paint or film.

Claims (1)

[Claims] 1 General formula R ¹ CO(-NH-Y-NH-X)-nNH-Y-NH-
COR ¹ is an organic polymer polyamide having an amide bond at the terminal represented by (), and is made of dimethylacetamide.
A soluble heat-resistant polyamide having an intrinsic viscosity (ηinh) of at least 0.30 dl/g, measured at 30° C. in a solution of 0.5 g of said polyamide in 100 ml. [However, R ¹ represents an alkyl group or an aromatic group, Y represents [formula] (however, R ² is either H, CH ₃ or C ₂ H ₅ ), and X represents [formula] and [ is at least a member of the group consisting of the formula], where n indicates the number of repeating units. 2. The soluble heat-resistant polyamide according to claim 1, which has an intrinsic viscosity of 0.35 dl/g or more. 3 At least pyridine, m-cresol, o-
Claim 1 dissolved in chlorphenol
Soluble heat-resistant polyamide as described in Section. 4. The soluble heat-resistant polyamide according to claim 1, wherein R ¹ in the general formula () is a methyl group, an ethyl group, or a phenyl group.