Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Shaping by extrusion
Reexamination Certificate
2008-11-25
2010-02-09
Teskin, Fred M (Department: 1796)
Plastic and nonmetallic article shaping or treating: processes
Forming continuous or indefinite length work
Shaping by extrusion
C264S331170, C526S126000, C526S131000, C526S160000, C526S348100
Reexamination Certificate
active
07658875
ABSTRACT:
A polymer film having a thickness of 10 microns or less and improved barrier characteristics to both water vapor and oxygen is formed from a biaxially-oriented polypropylene film of isotactic polypropylene. The polypropylene is prepared by the polymerization of propylene in the presence of an isospecific metallocene catalyst. The film has a permeability to water vapor of less than about 2.5 g/m2day/25 μm and a permeability to oxygen of less than about 2200 cc/m2day/25 μm. The film also has a haze properties of less than about 1%. The polypropylene contains 0.1 to 1% 2,1 insertions and has an isotacticity of at least 96% meso pentads. The isotactic polypropylene thus produced is then extruded into a sheet that is biaxially-oriented by stressing the sheet in the transverse and longitudinal directions to a draw ratio of at least about 6:1 in the transverse direction, and at least about 4:1 in the longitudinal direction.
REFERENCES:
patent: 5795946 (1998-08-01), Agarwal et al.
patent: 6090325 (2000-07-01), Wheat et al.
patent: 2007/0235896 (2007-10-01), McLeod et al.
Fina Technology, Inc.
Kilpatrick-Lee Diane L.
Teskin Fred M
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