Abstract:
PROBLEM TO BE SOLVED: To provide a method of depolymerizing a polyamide, whereby depolymerization of a polyamide is carried out without causing corrosion in a metallic apparatus; and to provide a production method for a monomer of a polyamide. SOLUTION: The method of depolymerizing a polyamide and the production method for a monomer of a polyamide are carried out through depolymerization of a polyamide by subjecting a ≥2C alcohol to act on a polyamide. The alcohol is a secondary or tertiary alcohol, or a ≥4C alcohol, being subjected to act in the state of supercritical. COPYRIGHT: (C)2007,JPO&INPIT
Abstract:
The present invention provides a process for the preparation of purified caprolactam comprising the steps of: (a) depolymerizing polyamide-containing carpet in the presence of steam to obtain crude caprolactam and steam; (b) removing substantially all of said water from said crude caprolactam and steam; (c) distilling the resulting concentrated crude caprolactam at a pressure of less than about 8 mmHg and a temperature from about 110 DEG C to about 145 DEG C so as to form overheads and bottoms of the caprolactam; and (d) crystallizing the caprolactam overheads to obtain caprolactam crystals and mother liquor. The resulting purified caprolactam may then be used to make polycaprolactam which may then be used in engineered materials or spun into fiber.
Abstract:
The invention concerns the preparation of caprolactam by cyclizing 6-aminocapronitrile in the presence of water at high temperature and optionally of a catalyst and a solvent by: a) separating from the reaction yield ("reaction yield I") of the cyclizing process caprolactam and all the components boiling higher than caprolactam ("high boilers"); b) treating the high boilers from step a) with phosphoric acid and/or polyphosphoric acid at a temperature ranging from 200 to 350 DEG C, obtaining reaction yield II; and c) separating the caprolactam resulting from reaction yield II of step b) and optionally 6-aminocapronitrile from unreacted "high boilers" and the acid used.
Abstract:
A process for the preparation of epsilon -caprolactam starting from 6-aminocaproic acid, 6-aminocaproamide, 6-aminocaproic ester, 6-aminocapronitrile, oligomers or polymers of these compounds or mixtures comprising at least two of these compounds, which process is performed in the presence of N-(5-carboxypentyl)- epsilon -caprolactam and/or derivative thereof in an amount of less than 50 wt.% and more than 0.1 wt.% (based on the total reaction mixture).
Abstract:
The present invention relates to a process for purifying an impure stream of caprolactam while recovering not only pure caprolactam but also medium-to-high pressure steam. Preferably, the stream of impure or crude caprolactam which comprises at a minimum a substantial portion of water, is obtained from depolymerization of a polyamide-containing composition. The resulting purified caprolactam will have a purity greater than 90 weight percent and the recovered steam will have a temperature sufficiently high to provide a driving force for use with other equipment, for instance, heat exchange equipment.
Abstract:
Caprolactam is obtained from caprolactam-containing polymers in the presence of superheated water by bringing polymers which contain the repeating unit -[-N(H)-(CH2)5-C(O)-]- or mixtures consisting essentially of -from 40 to 99.9% by weight of a polymer containing the repeat- - ing unit -[-N(H)-(CH2)5-C(O)-]-, -from 0.01 to 50% by weight of additives selected from the group - consisting of inorganic fillers, organic and - inorganic pigments and dyes, -from 0 to 10% by weight of organic and/or inorganic - additives, -from 0 to 40% by weight of non-polyamide-containing - polymers and -from 0 to 60% by weight of polyamides, with the exception of - polycaprolactam and copolyamides prepared - from caprolactam, - into contact with superheated water at from 280 DEG to 320 DEG C. and from 7.5 to 15 MPa and a weight ratio of water to polymer containing the repeating unit -[-N(H)-(CH2)5-C(O)-]- of from 5:1 to 13:1 and in a reaction time of less than 3 hours, with the proviso that the reaction mixture, consisting essentially of water and the polymer used or the mixture used, contains no gaseous phase under the conditions of the hydrolysis.