Opaque molecularly oriented and heat set linear polyester film and process for making same
AssigneeImperial Chemical Industries PLC
InventorsCarl Fraser Mathews, Christopher Deverell, Gordon Edmund Alfred Pears, Peter George Knowles
Life of this patent
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Abstract
Opaque voided films having a total luminous transmission not exceeding 25% are made from blends of a polyester preferably polyethylene terephthalate, with 3 to 27% of an ethylene or propylene polymer, prepared by dry blending. One end use of the film, as a base for photographic prints is also described.
Claims12
A process for the production of an opaque molecularly oriented and heat set linear polyester film, which comprises forming a loosely blended mixture of particles of a linear polyester produced by condensing at least one dicarboxylic acid, a lower alkyl diester thereof or bis-p-carboxyphenoxyethane with at least one glycol with from 3 to 27% by weight of particles of a homopolymer of ethylene or propylene, there being no intimate bond between the polyester and homopolymer, extruding the blended mixture as a film, quenching and biaxially orienting the film by stretching it in mutually perpendicular directions, and heat setting the film.
An opaque molecularly oriented and heat set linear polyester film produced from a blend of particles of a linear polyester produced by condensing at least one dicarboxylic acid, a lower alkyl diester thereof or bis-p-carboxyphenoxyethane with at least one glycol and from 3 to 27% by weight of particles of a homopolymer of ethylene or propylene and having a total luminous transmission of up to 30%, the homopolymer being dispersed in the form of discrete particles throughout the oriented and heat set film.
Dependencies are inferred from the claim text.