Production of improved pellets from melt-processable polymer which is capable of forming and anisotropic melt
US4581443A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 9, 1984 |
| Grant date | Apr 8, 1986 |
| Priority date | — |
| Expiry date | Oct 9, 2004 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29K2077/00
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
Improved pellets comprising a melt-processable thermotropic liquid crystalline polymer (e.g., a wholly aromatic polyester) are provided. The molten anisotropic melt-forming polymer, while present as a thin film of the specified thickness at an appropriate temperature, is subjected to reduced pressure conditions whereby residual volatiles are evolved and removed, and the polymer thereby is densified to the specified degree prior to pellet formation. The resulting densified polymer next is melt-extruded and is cut to form pellets while at an appropriate temperature. It surprisingly has been found to be of prime importance that the resulting pellets possess a density of at least 95 percent of the theoretical maximum (e.g., a polymer density of approximately 1.35 to 1.4 gram/cc.) if the advantages of the present invention are to be fully realized. These pellets have been found to be capable of undergoing melt processing to form shaped articles having improved physical properties. For instance, such shaped articles exhibit markedly smoother surface characteristics and can be used at elevated temperatures for extended periods of time while better retaining the desired surface characteris…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.