Process for the continuous melt thermoforming of polymers
US4061706A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 22, 1975 |
| Grant date | Dec 6, 1977 |
| Priority date | — |
| Expiry date | Oct 22, 1995 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29C51/365
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A process for the continuous melt thermoforming of thermoplastic polymers is disclosed. The process comprises extruding a flat web of molten polymer in a downward direction and directly over a series of mould cavities moving at a predetermined speed thereby sequentially covering the mould cavities. A vacuum is applied to the mould cavities and the web of molten polymer is brought into contact with the surface of the mould cavity, the mould defining the mould cavity being comprised of porous metal. The polymer is cooled and the resultant article is removed from the mould. The process is controlled so that the articles thermoformed in the process are of substantially uniform thickness. In embodiments the mould cavities are located on the periphery of a continuous belt or preferably a wheel. The process may be operated with polymers of low zero shear viscosity. The preferred polymers are polyamides, especially polyhexamethylene adipamide, of relative viscosity in the range 25 to 65. Substantially inflexible open containers comprised of a polyamide having a relative viscosity in the range 25 to 65 are also disclosed. The containers may be of thickness in the range of 2 to 30 mils.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.