Process for the production of finely divided and free-flowing powders of thermotropic polymers
US5100605A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 13, 1990 |
| Grant date | Mar 31, 1992 |
| Priority date | — |
| Expiry date | Nov 13, 2010 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08J2367/02
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
Finely divided and free-flowing powders of a thermotropic polymer, e.g., a wholly aromatic polyester or a wholly aromatic polyesteramide, are produced by (a) extruding a melt of such thermotropic polymer through an extrusion apparatus including a downstream die member to provide at least one solid cylindrical profile thereof, during which extrusion (i) the molten thermotropic polymer is at a temperature T.sub.1 greater than the melting temperature T.sub.M thereof at which the liquid crystal phase develops, while (ii) cooling such molten thermotropic polymer no later than the instant of its inlet entry into the die member to a temperature T.sub.2 ranging from a value 7.degree. C. less than the temperature T.sub.M to a minimum value equal to the crystallization temperature T.sub.c thereof, and (iii) maintaining this temperature T.sub.2 of the molten thermo-tropic polymer during extrusion thereof through the die member, and then (b) granulating and grinding the at least one solid cylindrical profile thus provided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.