RU97112178A

RU97112178A - METHOD FOR PRODUCING CAPROLACTAM BY HYDROLYTIC CRIMPTION OF MELTED POLYCAPROLACTAM

Info

Publication number: RU97112178A
Application number: RU97112178/04A
Authority: RU
Inventors: Басслер Петер; Копитц Михаэль
Original assignee: Басф Акциенгезельшафт
Priority date: 1994-12-12
Filing date: 1995-12-01
Publication date: 1999-06-27

Claims

1. The method of separation of caprolactam from caprolactam-containing polymers in the presence of superheated water, characterized in that the polymers containing repeating units
- [- N (H) - (CH ₂ ) ₅ -C (O) -] -,
or mixtures consisting mainly of 40-99.99 weight. % of one polymer with repeating units
- [- N (H) - (CH ₂ ) ₅ -C (O) -] -,
from 0.01 to 50% by weight of additives selected from the group consisting of inorganic fillers, organic or inorganic pigments and dyes, from 0 to 10% by weight. organic and / or inorganic additives, from 0 to 40% weight. polyamide-free polymers, from 0 to 60% weight. polyamide, with the exception of polycaprolactam and copolyamides obtained on the basis of caprolactam, is brought into contact with superheated water with a temperature in the range from 280 to 320 ^o C and pressure in the region from 7.5 to 15 MPa with a weight ratio of water to polymer with repeating units - [ -N (H) - (CH ₂ ) ₅ -C (O) -] -, equal to from 5: 1 to 13: 1, and the reaction time is less than 3 hours, provided that the reaction mixture, consisting mainly of water and the polymer used or the mixture used, in the conditions of hydrolysis does not contain a gaseous phase.

2. The method according to p. 1, characterized in that the following stages are carried out: (a) melting and compressing the polymer or mixture at a temperature in the range from 250 to 350 ^{° C.} and a pressure in the region from 7.5 to 30 MPa to obtain melt A, (b) mixing water with a temperature in the range from 280 to 320 ^{° C.} and a pressure in the range of 7.5 to 15 MPa with melt A in the hydrolyzer, (c) unloading the non-gaseous phase from the hydrolyzer into a relaxation device to obtain a gaseous phase B, and non-gaseous phase C, (g) separation, if necessary, of the non-fluid part With the second phase to obtain a liquid phase D, containing caprolactam, and a solid phase E and (d) a liquid phase D optionally obtained in step (g) is fed to a purification stage for caprolactam.

3. Device for isolating caprolactam from polymers containing repeating units
- [- N (H) - (CH ₂ ) ₅ -C (O) -] -,
or mixtures, consisting mainly of 40-99.9 wt.% one polymer with repeating units
- [- N (H) - (CH ₂ ) ₅ -C (O) -] -,
from 0.01 to 50% weight. additives selected from the group consisting of inorganic fillers, organic and inorganic pigments and dyes, from 0 to 10% weight. organic and / or inorganic additives, from 0 to 40% weight. polyamide-free polymer, from 0 to 60% weight. polyamides, with the exception of polycaprolactam and copolyamides obtained on the basis of caprolactam, by hydrolysis with superheated water, consisting mainly of a device for melting (1), to which a hydrolyzer (2) is connected to mix and carry out hydrolysis, as well as a relaxation hydrolyzer (2) device (3) and separation device (4).

4. The use of the device according to p. 3 for the recycling of waste containing polycaprolactam.

5. The use of the method according to p. 1 and 2 for the recycling of waste containing polycaprolactam.

6. The method according to p. 1, characterized in that instead of polymers containing repeating units - [- M (H) - (CH ₂ ) ₅ -C (O) -] -, oligomers containing repeating units - [- N (H) - (CH ₂ ) ₅ -C (O) -] -.