Polyester film and method of manufacture thereof
AssigneeToray Industries, Inc.
InventorsMasaaki Ono, Kazuo Okabe, Yasuki Miura
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Abstract
A slippery and smooth-surfaced polyester film, at least one surface of which is covered with worm-like nodules, useful as a base film for high recording density magnetic tape.
Claims39
A polyester film at least one surface of which is covered with worm-like nodules containing a mixture of an essentially water soluble polymer having a molecular weight of about 10,000-2,000,000 and at least one water emulsifiable polymer selected from the group consisting of (A) polysiloxane having a molecular weight of about 30,000-300,000 and (B) styrene butadiene rubber having a molecular weight of about 20,000-1,000,000, the weight ratio of said water soluble polymer to said water emulsifiable polymer in the mixture being about 1-100:5-50.
A method of manufacturing a coated polyester film which comprises:
- (a) coating at least one surface of a unidirectionally oriented polyester film with a water emulsion containing a water soluble polymer having a molecular weight of about 10,000-2,000,000 and a water emulsifiable polymer selected from the group consisting of (A) polysiloxane having a molecular weight of about 30,000-300,000 and (B) a styrene butadiene rubber having a molecular weight of about 20,000-1,000,000, and water;
- (b) drying the coated film;
- (c) transversely stretching the dried film;
- and
- (d) heat setting the transversely stretched film,
- the weight ratio of said water soluble polymer to said water emulsifiable polymer in the mixture being about 1-100:5-50.
Dependencies are inferred from the claim text.