摘要:
A process for producing polyamides by reacting at least one lactam and optionally further polyamide-forming monomers with aqueous monomer and oligomer extracts obtained during the extraction with water of the polymer product obtained in the production of polyamides, the water content of the reaction mixture being in the range from 0.5 to 13% by weight comprises conducting the reaction in the presence of metal oxides, beta-zeolites, sheet-silicates or silica gels, which may be doped, as heterogeneous catalysts, the heterogeneous catalysts being used in the form which permits mechanical removal from the reaction mixture and are removed from the reaction mixture in the course of the polymerization or after it has ended.
摘要:
A process for preparing a polyamide by reacting at least one aminonitrile with water comprises: (1) reacting at least one aminonitrile with water at a temperature from 100 to 360° C. and a pressure from 0.1 to 35×106 Pa to obtain a reaction mixture, (2) further reacting the reaction mixture at a temperature from 150 to 400° C. and a pressure which is lower than the pressure in step 1, the temperature and the pressure being selected so as to obtain a first gas phase and a first liquid or a first solid phase or a mixture of first solid and first liquid phase, and the first gas phase is separated from the first liquid or the first solid phase or from the mixture of first liquid and first solid phase, and (3) admixing the first liquid or the first solid phase or the mixture of first liquid and first solid phase with a gaseous or liquid phase comprising water at a temperature from 150 to 360° C. and a pressure from 0.1 to 30×106 Pa to obtain a product mixture.
摘要:
An apparatus (1) is proposed for drying and heat-treating pellets with a stream of inert gas, wherein the apparatus has a cuboid base unit (2) with a feed (3) for the pellets in its upper part and an outlet (4) in its lower part, with a feed (5) on one lateral surface and with an exhaust base (6) on the opposite lateral surface of the cuboid base unit (2) for the stream of inert gas, and also with distribution and retention equipment (7, 8) in the region of the feed (5) and, respectively, of the exhaust (6) for the stream of inert gas, where each of these extends essentially over the entire vertical cross section of the cuboid base unit (2).
摘要:
A process for continuous extraction of polyamide particles using a recirculating extractant in a vertical extraction column that is divided into two zones comprises treating the polyamide with an aqueous extractant comprising from 40 to 95% by weight of &egr;-caprolactam in a first zone at from 100 to 140° C., and then effecting an aftertreatment with water in a second zone. The caprolactam can then be extracted in a conventional manner. The process provides for economical production of polyamide having a low dimer content.
摘要:
A process for continuous extraction of polyamide particles in an essentially vertical extraction column using an aqueous extractant comprises using an extraction column that is divided into two zones and performing an extraction with a recirculating 15-40% strength by weight aqueous &egr;-caprolactam solution in the first zone and then with countercurrent water at a from 5 to 40° C. lower temperature in the second zone. The process provides for economical extraction of polyamides with a low level of monomers and oligomers.
摘要:
A process for continuous production of copolyamides based on a lactam (I), a diamine (II) and a dicarboxylic acid (III) comprises reacting a mixture (IV) comprising a diamine (II), a dicarboxylic acid (III) and water in a first reaction zone at a pressure in the range from 1.3*105 to 2.5*105 Pa in the entry zone of the reaction zone and at a temperature above the melting point of polymer (V) to a conversion, based on the molar amounts of diamine (II) and dicarboxylic acid (III), of at least 80% to form a polymer (V), reacting a mixture (VI) comprising lactam (I) and water in a second reaction zone at a pressure in the range from 5*105 to 40*105 Pa and at a temperature above the melting point of polymer (VII) to a conversion, based on the molar amount of lactam (I), of at least 80% to form a polymer (VII), then reacting polymer (V) and polymer (VII) with each other in a third reaction zone at a pressure in the range from 1*105 to 1.5*105 Pa in the entry zone of the reaction zone at temperatures above the melting point of polymer (VIII) to form a polymer (VIII), said polymer (VIII) having a 95° C. water extractables content, based on lactam (I), diamine (II) and dicarboxylic acid (III), of not more than 10% by weight, and then extracting the polymer (VIII) with water to obtain the copolyamide.
摘要:
A process for preparing salts of polyaspartic acid by treating polycondensates in aqueous medium with bases, employing at least 0.7 equivalent of an alkali metal and/or alkaline earth metal base per mole of the aspartimide, aspartic acid and/or aspartamide units present in the polycondensates, and the bases being added within from 30 min to 20 hours to an aqueous suspension of polycondensates of aspartic acid which has been heated to 40.degree.-140.degree. C., and the reaction mixture being allowed to react further where appropriate, and the use of alkali metal and/or alkaline earth metal salts of polyaspartic acids obtainable by treating polycondensates of aspartic acid in aqueous medium with more than 1 equivalent of an alkali metal and/or alkaline earth metal base, with the molecular weight of the polycondensates being reduced, as additive to detergents and cleaners.
摘要:
The disclosure is a process for preparing polyamides by concentrating the wash water extract from the extraction of polyamide to an extractables content of not more than 85% by weight, adding fresh lactam down to a water content of from 0.5 to 13% by weight, and effecting at least one adiabatic expansion during the polymerization.
摘要:
A process for preparing polyaspartic acid by polycondensation of fine-particle aspartic acid at temperatures above 150.degree. C. in the presence of acidic catalysts, wherein first contact between the acidic catalysts and the fine-particle aspartic acid takes place in the reaction zone where the polycondensation takes place.