Abstract: The invention relates to a method for synthesizing a polyamide, in which method an aqueous solution is sprayed onto the polyamide before and/or during a solid-state post-condensation process. The aqueous solution comprises at least a first compound, selected from the group comprising phosphoric acid, fully neutralized salts of phosphoric acid, partially neutralized salts of phosphoric acid, and mixtures thereof, and a second compound, selected from the group comprising an acid, an anhydride, a lactone, ammonia, an amine, and mixtures thereof, with the stipulation that the second compound is not phosphoric acid and is not phosphoric acid anhydride. The spraying occurs at a temperature that lies below the boiling point of water. A polyamide that can be produced by means of the method according to the invention can be used in particular to produce films, monofilaments, fibers, threads, or textile sheet materials.

Abstract: The present invention provides a process for producing polyamides, which comprises a) providing a monomer composition comprising at least one lactam or at least one aminocarbonitrile and/or oligomers of these monomers, b) reacting the monomer composition provided in step a) in a hydrolytic polymerization at elevated temperature in the presence of water to obtain a reaction product comprising polyamide, water, unconverted monomers and oligomers, c) the reaction product obtained in step b) being fed into at least one kneader (3) and subjected to a postpolymerization, d) optionally forming the reaction product obtained in step c) to obtain polyamide particles, e) optionally treating the reaction product obtained in step c) or the polyamide particles obtained in step d) with at least one extractant.

Abstract: The invention relates to a method for synthesizing a polyamide, in which method an aqueous solution is sprayed onto the polyamide before and/or during a solid-state postcondensation process. The aqueous solution comprises at least a first compound, selected from the group comprising phosphoric acid, fully neutralized salts of phosphoric acid, partially neutralized salts of phosphoric acid, and mixtures thereof, and a second compound, selected from the group comprising an acid, an anhydride, a lactone, ammonia, an amine, and mixtures thereof, with the stipulation that the second compound is not phosphoric acid and is not phosphoric acid anhydride. The spraying occurs at a temperature that lies below the boiling point of water. A polyamide that can be produced by means of the method according to the invention can be used in particular to produce films, monofilaments, fibers, threads, or textile sheet materials.

Abstract: The invention relates to a process for working up particulate crude polyoxymethylene, which comprises the following steps: (a) introduction of the particulate crude polyoxymethylene into an extraction column (13) operated at a pressure in the range from 1 to 6 bar, (b) introduction of a polar extractant into the extraction column (13) with a temperature in the range from 95 to 140° C. and a pressure in the range from 1 to 6 bar, wherein from 10 to 1000 ppm, based on the amount of polar extractant introduced, of a buffer substance which buffers in the pH range from 7.5 to 11.5 are introduced into the extraction column (13).

Abstract: A process for producing polyamides from the corresponding monomers and/or prepolymers comprises the steps of (a) reacting the monomers and/or prepolymers and optionally further components under polyamide-forming reaction conditions to form polyamide, (b) treating the polyamide obtained in step (a) in a kneader above the melting temperature of the polyamide, (c) further processing the polyamide from step (b) into pellet, film, fiber or moldings, preferably pelletizing the polyamide, (d) extracting some or all unconverted monomers and any product dimers and oligomers and also optionally further components from the polyamide and/or drying the polyamide.

Abstract: The invention relates to a process for working up particulate crude polyoxymethylene, which comprises the following steps: (a) introduction of the particulate crude polyoxymethylene into an extraction column (13) operated at a pressure in the range from 1 to 6 bar, (b) introduction of a polar extractant into the extraction column (13) with a temperature in the range from 95 to 140° C. and a pressure in the range from 1 to 6 bar, wherein from 10 to 1000 ppm, based on the amount of polar extractant introduced, of a buffer substance which buffers in the pH range from 7.5 to 11.5 are introduced into the extraction column (13).