Purging agent and purging method
US6294120A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 18, 1997 |
| Grant date | Sep 25, 2001 |
| Priority date | — |
| Expiry date | Jun 18, 2017 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29C48/10
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A purging agent which contains an ethylene-vinyl alcohol copolymer and which satisfies the conditions specified by the equations (1) and (2) below: EQU 20.gtoreq.BT.sub.(120).gtoreq.0.1 (1) EQU 500.gtoreq.BT.sub.(250) /BT.sub.(120).gtoreq.1.5 (2), PA1 where BT.sub.(120) is weight loss (%) on heating in nitrogen at 120.degree. C. for 24 hours, and BT.sub.(250) is weight loss (%) on heating in nitrogen at 250.degree. C. for 6 hours, rapidly discharges residual thermoplastic resin containing EVOH from molding equipment, and also rapidly discharges itself when a fresh resin is fed again to the equipment. This leads to a remarkable reduction in loss due to residual purging agent. In addition, the purging agent causes only a small amount of resin to stick to the equipment, even after repeated purging. After purging, it is possible to restore normal operation within a short period of time.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.