摘要:
The present invention relates to a process for preparing a polyamide based on dicarboxylic acids and diamines, comprising the following stages: A) providing an aqueous monomer mixture composed of dicarboxylic acids and diamines, where the molar ratio of dicarboxylic acids to diamines is adjusted such that, at the outlet of stage C), there is a molar deficiency of dicarboxylic acids or diamines of 1 to 10 mol%, based on the respective other component, B) transferring the aqueous mixture from stage A) into a continuous evaporator reactor in which diamines and dicarboxylic acids are converted at a temperature in the range from 100 to 370° C. and a pressure in the range from 1 to 50 bar, C) transferring the mixture from stage B) into a separator which is operated at a temperature in the range from 100 to 370° C. and a pressure in the range from 1 to 50 bar with removal of gaseous components, D) transferring the mixture from stage C) together with diamine or dicarboxylic acid in an amount suitable for compensation for the molar deficiency into a tubular reactor which is operated at a temperature in the range from 100 to 370° C. and a pressure in the range from 1 to 50 bar, for a residence time in the range from 10 seconds to 30 minutes, E) transferring the mixture from stage D) into an extruder which is operated at a temperature in the range from 150 to 400° C. for a residence time in the range from 10 seconds to 30 minutes with removal of gaseous components through venting orifices.
摘要:
The present invention relates to an improved pultrusion process for producing semifinished products based on polymers, in particular polyesters or polyamides, which comprises adding reactive chain extenders during the process of saturation (impregnation) of the fibers.
摘要:
The present invention relates to a process for preparing a composition comprising (A) at least one lactam, (B) at least one catalyst, (C) an activator from the group consisting of isocyanates, acid anhydrides, acyl halides, reaction products thereof with (A) and mixtures thereof, (D) at least one polyethyleneimine. The invention likewise relates to a composition comprising (i) 0.01 to 10 wt %, based on the sum total of components (A) and (D), of at least one polyethyleneimine, and (ii) 90 to 99.99 wt %, based on the sum total of components (A) and (D), of at least one lactam (A) and/or polyamide obtainable from (A).
摘要:
Semiaromatic, semicrystalline copolyamide molding compositions, comprising A) from 35 to 100% by weight of a copolyamide composed of a1) from 35 to 69% by weight of units which derive from hexamethylenediamine and from an aromatic dicarboxylic acid having from 8 to 16 carbon atoms, a2) from 31 to 65% by weight of units which derive from 3,3′-dimethyl-4,4′-diaminodicyclohexylmethane and from terephthalic acid, a3) from 0 to 30% by weight of units of a semicrystalline polyamide different from a1) and a2), B) from 0 to 65% by weight of further additives, where the total of the percentages by weight of A) and B) is 100%.
摘要:
The invention relates to a process for producing fiber-reinforced flat semifinished products based on a polyamide matrix, comprising the following steps: (a) saturation of textile structures with a mixture comprising molten lactam, catalyst, and optionally activator, (b) cooling of the saturated textile structures, and (c) finishing of the cooled textile structures to give the fiber-reinforced flat semifinished product. The invention further relates to a process for producing a component made of the fiber-reinforced flat semifinished product.
摘要:
The invention relates to a process for producing moldings made of a fiber-reinforced polymer, comprising the following steps:(a) inserting a fiber structure into a mold and injecting a polymer precursor compound around the fiber structure or saturating a fiber structure with a polymer precursor compound and inserting the saturated fiber structure into a mold, where the viscosity of the polymer precursor compound is at most 2000 mPas,(b) polymerizing the polymer precursor compound to give the polymer, to produce the molding,(c) removing the molding from the mold as soon as the polymerization process has proceeded at least to the extent that the molding is in essence dimensionally stable.
摘要:
A process for producing an activated monomer composition comprising at least one lactam and/or lactone, one catalyst, and one activator permits storage of the resultant monomer composition, since this is stable with respect to polymerization. Said monomer composition is used inter alia in producing a polyamide molding via ring-opening, anionic polymerization.
摘要:
Polyamides based on dicarboxylic acids and on diamines are produced in a batch process by 1) feeding the entire amount of monomer composed of dicarboxylic acids, of diamines, and, if appropriate, of further polyamide-forming monomers, in the desired stoichiometry, in a closed stirred-tank reactor, 2) heating the monomer mixture in the stirred-tank reactor, with stirring, and with setting of a certain pressure, to a desired reaction temperature for the production of a prepolymer, 3) if appropriate, completely or partially depressurizing the reaction mixture from stage 2), 4) if appropriate, carrying out further thermal treatment of the reaction mixture from stage 2) or 3), and 5) reacting the reaction mixture from stage 2), 3), or 4) in the melt in a vented extruder for further increase of the molecular weight, with discharge of water vapor, and without use of additional polyamide-forming monomers or of polyamides.