Method for producing transparent plastic molded articles
US4118454A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 27, 1976 |
| Grant date | Oct 3, 1978 |
| Priority date | — |
| Expiry date | Aug 27, 1996 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29C51/002
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
This invention provides a simple and advantageous method for producing plastic moldings with good surface gloss, very excellent transparency and high stiffness from crystalline polypropylene sheets manufactured by a generally employed industrial method without adversely affecting mechanical strength, shape retention at high temperatures and other properties according to a thermoforming process. This invention, more specifically, concerns a method for producing transparent polypropylene molded articles, characterized by heating a polypropyleneretention at high temperatures and other properties according to a thermoforming process. This invention, more specifically, concerns a method for producing transparent polypropylene molded articles, characterized by heating a polypropylene sheet at a temperature higher than the melting point thereof, stretching it by more than 5%, rapidly cooling it to a temperature of not more than 120.degree. C, and then subjecting the thus treated sheet to thermoforming at a temperature below the melting point of the sheet.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.