Heat-sealable polypropylene blends and methods for their preparation
AssigneeRJ Archer Inc.
InventorsJohn G. Brandt, Joyce H. Dickerson, William R. Schmitt
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Abstract
This invention relates to blends of polypropylene and styrene-terpene copolymers which provide biaxially oriented, corona discharge treated, heat-sealable films useful in the packaging art. Preferably the compositions also contain a saturated fatty amide, e.g., stearamide slip agent and/or a Fischer-Tropsch wax. A process is described when the films after biaxial orientation, are treated by a corona discharge and in some cases heat aged prior to use in the packaging art.
Claims31
A heat-sealable film consisting essentially of a corona discharge treated, biaxially oriented film comprising a blend of stereoregular polypropylene containing about 5% to about 25% by weight based on the total composition of a terpene-styrene or substituted styrene copolymer consisting of about 85% to about 25% terpene and about 15% to about 75% styrenic monomer.
A heat-sealable film comprising a corona discharge treated, biaxially oriented film comprising a blend of stereoregular polypropylene containing about 5% to about 25% by weight based on the total composition of a terpene-styrene or substituted styrene copolymer consisting of a copolymer of about 85% to about 25% terpene and about 15% to about 75% styrenic monomer, and containing a coefficient of friction reducing, nonheat-seal preventing amount between about 0.02% to about 0.1% of a saturated fatty amide slip agent.
A method of forming a heat-sealable polypropylene film which comprises subjecting a biaxially oriented film consisting essentially of a film comprising a blend of stereoregular polypropylene containing about 5% to about 25% by weight based on the total composition of a terpene-styrene or substituted styrene copolymer consisting of about 85% to about 25% terpene and about 15% to about 75% styrenic monomer to a corona discharge in an amount sufficient to enhance the heat-sealability of the film.
A method of forming a heat-sealable polypropylene film which comprises subjecting a biaxially oriented corona discharge treated film consisting essentially of a film comprising a blend of stereoregular polypropylene containing about 5% to about 25% by weight based on the total composition of a terpene-styrene or substituted styrene copolymer consisting of a copolymer of about 85% to about 25% terpene and about 15% to about 75% styrenic monomer, and containing a coefficient of friction reducing, non-heat-seal preventing amount between about 0.02% to about 0.1% of a saturated fatty amide slip agent to an aging at an elevated temperature for a time sufficient to reduce the coefficient of friction of the film.
A film having enhanced heat-sealability comprising a corona discharge treated, biaxially oriented film comprising a blend of stereoregular polypropylene containing about 5% to about 25% by weight based on the total composition of a terpene-styrene or substituted styrene copolymer consisting of a copolymer of about 85% to about 25% terpene and about 15% to about 75% styrenic monomer, where the film has been treated with corona discharge in an amount sufficient to enhance the heat sealability of the film, the corona discharge being conducted in a manner such that the temperature of the film is maintained below about 150.degree. F.
Dependencies are inferred from the claim text.