Composite polyester films and process for producing the same
US3983285A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 4, 1974 |
| Grant date | Sep 28, 1976 |
| Priority date | — |
| Expiry date | Jun 4, 1994 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/31786
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A monoaxially or biaxially drawn composite polyester film comprising at least two layers of polyesters having different physical properties. At least one polyester layer is produced utilizing a catalytic system wherein the catalyst residue is insoluble in the polymer and at least one other polyester layer is produced using a catalyst system wherein the catalytic residue is soluble or only slightly insoluble in the polyester. A process for producing such composite polyester film comprises coextruding at least two polyester polymers into a layered film, one of these polyester layers containing crystallization sites in the form of the residue of the interchange catalyst used to form the polyester, and at least one polyester layer comprising a polyester wherein the interchange catalyst system is soluble or only slightly insoluble in the polyester; and drawing the layered film either monoaxially or biaxially. These films have particular utility as support for magnetic recording tapes wherein one face of the film to be coated is smooth and the opposite face (undersurface) of the film has surface roughness.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.