Polyester films with improved processability and tear resistance
AssigneeMinnesota Mining and Manufacturing Company
InventorAndrew H. Wong
Life of this patent
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Abstract
Polyester films consisting of a homogeneous fused, intimate mixture of polyethylene terephthalate (PET) with sufficient polytetramethylene terephthalate (PTMT) to increase film tear strength in excess of 10%. Mixed PET and PTMT resins are extruded and used to produce unoriented, uniaxially oriented, and biaxially oriented polyester films with significantly increased tear strengths. Increased tear strengths are exhibited at different PET-PTMT weight ratios depending upon the orientation of the film.
Claims12
A tear resistant polyester film consisting essentially of a homogeneous blended mixture of polyethylene terephthalate (PET) resin and sufficient polytetramethylene terephthalate (PTMT) resin so as to increase the tear strength of the film by at least 10% more than that exhibited by either PET or PTMT, said film being heat set at a temperature in the range of about 160.degree. C. to 220.degree. C. and having a thickness between about 6.3 micrometers and about 500 micrometers.
A uniaxially oriented, heat set polyester film comprising the extrusion product of a homogeneous mixture of polyethylene terephthalate resin, and polytetramethylene terephthalate resin, wherein said film comprises 20 to 80 percent by weight polyethylene terephthalate, the remainder of said film comprising polytetramethylene terephthalate, said uniaxial orientation is accomplished by elongating said film along an axis in the range of 2.5.times. to 3.5.times., heat setting is accomplished at in the range of 175.degree. C. to 205.degree. C., and wherein said film has a thickness in the range of 12.5 micrometers to 130 micrometers.
Dependencies are inferred from the claim text.