Method of press-molding thermoplastic resins
US5795510A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 9, 1996 |
| Grant date | Aug 18, 1998 |
| Priority date | — |
| Expiry date | Oct 9, 2016 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29K2101/12
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A thermoplastic resin is molded by a press-molding method wherein a thermoplastic resin in a molten state is compressed to flow between a pair of female and male molds so as to be formed into a predetermined shape. A compression rate of the mold is controlled so that the following expression (1) is satisfied: EQU 0.5.ltorsim.B/A.ltorsim.2 (1) wherein A (mm/s.sup.2) is an acceleration which is realized at a time when the compression rate is 75% of a maximum rate in a compression-acceleration region, which region is defined as a period of time from a moment when the compression of the molten thermoplastic resin is started to a moment when the compression rate reaches the maximum rate; and B (mm/s.sup.2) is a deceleration which is realized at a time when the compression rate is 75% of the maximum rate in a compression-deceleration region, which region is defined as a period of time from a moment when the compression rate reaches the maximum rate to a moment when the closing of the molds is complete. By this method, a molded article having excellent surface appearance free from unevenness of gloss and surface irregularity can be obtained.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.