Polyester film and process for producing the same
AssigneeToray Industries, Inc.
InventorsKatsuya Okamoto, Koichi Abe, Shoji Nakajima
Life of this patent
Estimating the term…
Abstract
A polyester film has a surface layer whose major component is polyester A wherein protrusions formed on the film surface originating from the crystallization of polyester A. The number of protrusions formed on the surface of the film is not less than 5.times.10.sup.3 /mm.sup.2, and the ratio N.sub.R of the number of protrusions to the number of particles contained in a surface layer forming the surface of the film is not less than 5. Since most of or the whole of the protrusions are formed by the crystallization of polyester A as opposed to particles, generation of voids can be prevented fine and uniform protrusions having excellent chipping resistance and scratch resistance can be formed.
Claims13
A polyester film comprising a biaxially oriented polyester film comprising polyester A, wherein the number of protrusions formed on at least one surface of said film is not less than 5.times.10.sup.3 /mm.sup.2 and the ratio N.sub.R of said number of protrusions to the number of particles contained in a surface layer forming said at least one surface of said film is not less than 5, and the crystallization parameter .DELTA. Tcg of said polyester A is not more than 70.degree. C., wherein not less than 70% of said protrusions are formed from crystallization.
A laminated polyester film comprising:
- a layer B of a polyester film comprising polyester B;
- and
- a layer A of a biaxially oriented polyester film laminated on at least one surface of said layer B, said biaxially oriented polyester film comprising polyester A, the number of protrusions formed on the surface of said layer A being not less than 5.times.10.sup.3 /mm.sup.2, the ratio N.sub.R of said number of protrusions to the number of particles contained in a surface layer forming said surface of said layer A being not less than 5, wherein the crystallization parameter .DELTA. Tcg of said polyester A is not more than 70.degree. C., wherein not less than 70% of said protrusions are formed from crystallization.
Dependencies are inferred from the claim text.