Foamed and expanded beads of polypropylene resin for molding
US6077875A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 23, 1999 |
| Grant date | Jun 20, 2000 |
| Priority date | — |
| Expiry date | Mar 23, 2019 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08J2323/16
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
Disclosed herein are foamed and expanded beads of a polypropylene resin for molding, which comprise an uncrosslinked propylene random copolymer having a melting point of at least 140.degree. C. as a base resin, wherein the time required to attenuate an air pressure within the foamed beads applied by a pressurizing treatment with air from 1.2 kgf/cm.sup.2 (G) to 0.8 kgf/cm.sup.2 (G) under atmospheric pressure at 23.degree. C. is at least 80 minutes, and the CNI value of the foamed beads, which is defined by the following equation (1): EQU CNI=log.sub.10 [Pw.times.Er.div.(2.24.times.D.sup.3 .times.B)](1) wherein Pw is an average weight (mg) per foamed bead, Er is a bulk expansion ratio (time) of the foamed beads, D is a cell diameter (mm) of the foamed beads, and B is a density of the base resin, is smaller than 3.80.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.