SU565045A1 - Method for obtaining polyimides - Google Patents

Description

A mixture of hexamethylenediamine with a longer chain diamip is also used as an aliphatic component in order to obtain more flexible polymers, with the molar ratio of the latter varying from 0.9: 0.1 to 0.1: 0.9. The copolymiids obtained have a relatively low melt viscosity, which allows them to be processed by injection molding, extrusion, pressing, etc. Mixed polyimides are obtained in one stage at elevated temperatures (up to 215-220 ° C) in nitrobenzene solution, or two-stage method with thermal and chemical cyclization of previously obtained polyamic acid in solution by mixtures of tertiary amines with carboxylic anhydrides or alkali metal carboxylates with carboxylic anhydrides or chlorides or with the help of other agents. The copolymiids obtained are completely amorphous polymers with a glass transition temperature well below the onset of decomposition, soluble in various organic solvents (chloroform, methylene chloride, C.sub.2-tetrachloroethane, M, 1H-dimethylformamide, M, M-dimethylacetamide, N -methylpyrrolidone, dimethyl sulfoxide, nitrobenzene, benzonitrile, cresol, dioxane, etc.) with a logarithmic viscosity of at least 0.6 dl / g. These polymers are processed by extrusion, molding, extrusion and other methods and produce durable products that retain high mechanical and electrical characteristics under conditions of high temperatures and high humidity. Polyimides retain almost unchanged their electrical insulating properties after exposure for 56 days under conditions of tropical humidity, as well as at high temperatures (up to 250-270 ° C) and after heat aging for 1000 h at 200 ° C. The weight and dimensions of the discs of this polyimide stabilize after 400 hours of heat shrinkage at 200 ° C. The shrinkage of the product during this time is 0.45%, and the loss in weight is 0.5%. Polyimides obtained by the proposed method have high heat resistance: according to TGA, polymers lose 5% in weight at 400–420 ° C. Polyimides do not lose their technological properties during processing and may be repressed or re-cast several times. Polyimides obtained by the proposed method can be recommended as structural casting materials for contact body and thin-walled (at least 0.5 mm) parts for an operating temperature of 200 ° C. Example 1. In a three-liter flask with a capacity of 2 liters, equipped with a stirrer, a bubbler to pass through a dry inert gas (argon or nitrogen), 87 g (0.25 mol) 9.9 bis - (4-aminophenyl) - Fluorene, 29 g (0 , 25 mol) hexamethylenediamine, 155 g 0.5 mol) 3.3, 4.41-tetracarboxydiphenyloxide and 1300 mol / g-nitrobenzene. With stirring and passing argon, raise the temperature in the bath for 1 -1.5 hours to 150-160 C. After 1-2 hours, the temperature in the bath is raised to 215-220 ° C and the reaction is carried out at this temperature for 12-14 hours At the end of the reaction and cooling, the reaction mixture is diluted with LNG tetrachloroethane to a concentration of 5–7% and the polymer is isolated by precipitation into methanol. The precipitated polymer is filtered off, and then subjected to extraction with acetone in a Soxhlet apparatus. The washed polymer is dried first in air at room temperature, and then in a vacuum oven at 80 ° C for 6-8 hours. The polymer has 0.6 dl / g (0.05 g of polymer in 10 ml syl-tetrachloroethane), soluble in nitrobenzene, cresol, tetrachloroethane, chloroform, etc. Monolithic samples with a specific impact strength of 40 kgf cm / cm and a tensile strength at static bend 1500 kgf / were made from the polymer obtained at 370-280 ° C and a pressure of 1200-1700 kgf / cm / cm, tensile strength at stretching is 1000 kgf / cm, electrical strength is 45 kg / mol. The specific volume electrical resistance is 5–10 cm. The dielectric loss tangent at a frequency of 10 Hz is 0.005. The dielectric constant 4, 0 after exposure for 100 h at 200 ° C, the samples lose 0.5% in weight; product shrinkage during this time is 0.45%. Example 2. To a solution containing 3.48 g of 9,9-bis- (4-aminophenyl) -fluorene, 1.16 g of hexamethylenediamine and 39 ml of 1,1-dimethylacetamide was added with stirring 6.2 g 3, PS, 4-tetracarboxydiphenyloxide and react at room temperature for 3 hours. Thereafter, the thick reaction solution is diluted with 32 ml of M, | M-dimethylacetamide, and acetic acid dianhydride and pyridine are added at a rate of 5 mol of acetic anhydride and 3.5 mol of pyridine per elemental link polymer. The reaction solution is stirred at room temperature for 2 hours, then the temperature is raised to 150 ° C and maintained at this temperature for another 2 hours. At the end of the reaction, the polymer is separated by precipitation into water, filtered, washed with water and acetone, and dried in a vacuum oven at 80 ° C. The polymer has 0.75 dl / g (0.05 g polymer in 10 ml of symmtetrachloroethane). According to X-ray analysis, the polymer has an amorphous structure. Example 3. In a three-necked flask equipped with a stirrer, a barbater for introducing an inert gas and a heated by-pass tube (example 1), 3.873 g of hexamethylenediamine, 3.4646 g of decamethylenediamine, 4.64 g of 9.9 bis (4-am-neofine) -fluorene, 20.667 g 3,3,4, 4-tetracarboxidiphenes (1lokl) and 167 ml of dry nitrobenzene. The molar ratio of the listed components is 0.5: 0.3:: 0.2: 1. With stirring and passing dry argon at a rate of 20 ml / min, raise the temperature of the reaction mixture to 150-160 ° C and maintain at this temperature for 1-1.5 hours. Then the temperature in the bath is raised to 210 ° C and the reaction is carried out at this temperature for 7-10 hours. At the end of the reaction, the heating is turned off, the reaction solution is cooled to room temperature, the polymer is separated by precipitation into acetone, filtered and extracted with acetone in a Soxhlet apparatus. The dried polymer has Tjin 0.8 dl / g (0.5 g of polymer in 100 ml of sylt-tetrachloroethane), soluble in nitrobenzene, cresol, tetrachloroethane, etc. According to X-ray structural analysis, the polymer has an amorphous structure.

Pr 1 m s p 4. To the solution containing 5.8 g of 9,9-bis- (4-aminophenyl) -fluorene, 1.93 g of hexamethylenediamine and 120 ml of N, N-dimethylacetamide are added with stirring 11 2 g of 2,2-bis (3,4-dicarboxphenyl) propane. The reaction is carried out at room temperature for 2 hours, then the temperature is raised to 1500 ° C and heated further for 2 hours. The polymer precipitate from the solution is filtered, washed with acetone and dried in a vacuum oven at 80 ° C. The polymer has a Tiin of 0.65 to / g (0.05 g of polymer in 10 ml of symmtetrachloroethane) and a body softening point of 245 ° C.

Example 5. In a three-neck flask, 17.0 g (0.085 mol) of dodecamethylenediamine are charged.

5.22 g (0.015 mol) of 9,9-bis- (4-aminophenyl) fluorene, 21.8 g (0.1 mol) of the pyromellane dianhydride and 330 ml of dry nitrobenzene. When mixing and passing dry

argon raise the temperature of the reaction mixture to 170-180 ° C and is maintained at this temperature for 1.5 hours. Then the temperature is raised to 200 ° C and stirred at this temperature for 7-10 hours.

the end of the reaction, the reaction solution is cooled to room temperature, while the polymer precipitates, which is filtered and washed with acetone. The polymer is amorphous, according to IR spectroscopy has an imide structure.

Example 6. Under conditions similar to those described in Example 5, the interactions were 3.48 g (0.01 mol) of 9.9-bis- (4-aminophenyl) -fluorene and 15.48 g (0.09 mol)

decamethylenediamine with 26.8 g (0.1 mol) of 1,4,5,8-naphthalene tetracarboxylic acid dianhydride in 330 ml of dry nitrobenzene. The polymer obtained according to IR spectroscopy has an imide structure.

Formula isobretiches

The method of producing polyimides by the interaction of tetracarboxylic acid dianhydrides

and diamonds of the cardaceous type, differing from the fact that, in order to give polymers the possibility of processing nz of the melt, aliphatic diamines are introduced into the reaction mixture at the molar ratio of dianhydride

tetracarboxylic acid, aliphatic diamine and diamine of the carda type from 1: 0.1:: 0.9 to 1: 0.9: 1.