Methods for manufacturing foam material including systems with pressure restriction element
US6322347A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 2, 1999 |
| Grant date | Nov 27, 2001 |
| Priority date | — |
| Expiry date | Apr 2, 2019 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29K2105/16
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
The invention provides systems, methods, and articles useful in the production of foams, and, in particular microcellular foams. The systems include a restriction element that reduces the backflow of polymer melt in an extruder while polymeric material is injected into a mold or ejected from a die. The restriction element is positioned upstream of a blowing agent injection port to maintain the solution of polymer and blowing agent in the extruder above a minimum pressure throughout an injection or ejection cycle, and preferably above the critical pressure required for the maintenance of a single-phase solution of polymer and blowing agent. The systems can be used in injection molding, blow molding, or in any other processing techniques that include injection or ejection cycles. In some embodiments, the systems utilize reciprocating screws for injection or ejection. In other embodiments, the systems include an accumulator connected to an outlet of the extruder, in which a plunger moves to inject polymeric material into a mold or eject polymeric material from a die.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.