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US 8,574,695 B2Granted
Biodegradable composite barrier film
AssigneeToray Plastics (America), Inc.
InventorsMark Lee, Nao Yokota, Keunsuk P. Chang
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AssigneeToray Plastics (America), Inc.
InventorsMark Lee, Nao Yokota, Keunsuk P. Chang
Estimating the term…
The present invention is directed to a multilayer film having, as its main component, a hydroxy acid polymer with improved gas barrier and optional heat sealability. The oriented film of predominately hydroxy acid polymer having controlled shrink can be produced by melting and coextruding a hydroxy acid polymer with a much thinner layer of an amorphous aromatic copolyester to form a multilayer film that is quench cooled, then biaxially stretched at a process temperature above the glass transition and below the cold crystallization temperature of the hydroxy acid polymer. A heat-setting treatment with a controlled relaxation of the film above the hydroxy acid polymer glass transition temperature and below its melt temperature may be used to control shrinkage. The films thus obtained are vacuum metallized on the aromatic copolyester surface to produce environmentally friendly packaging from predominately renewable resources having improved gas barrier properties.
A multilayer film comprising (i) a core layer comprising a major fraction by weight of the core layer of a poly(hydroxy acid), (ii) a polymeric barrier receiving layer adjacent to one side of the core layer and comprising amorphous poly(hydroxy acid) blended with an amorphous aromatic copolyester in which a major fraction by weight of the polymeric barrier receiving layer is amorphous aromatic copolyester, and (iii) a barrier layer adjacent the polymeric barrier receiving layer opposite the core layer, the barrier layer comprising an inorganic compound as a major fraction by weight of the barrier layer,
A multilayer film comprising (i) a core layer comprising a major fraction by weight of the core layer of a poly(hydroxy acid), (ii) a polymeric barrier receiving layer adjacent to one side of the core layer and comprising a major fraction by weight of the polymeric barrier receiving layer of an amorphous aromatic copolyester, (iii) a barrier layer adjacent the polymeric barrier receiving layer opposite the core layer, the barrier layer comprising an inorganic compound as a major fraction by weight of the barrier layer, and (iv) on a side of the film opposite the barrier layer at least one additional layer of which the farthest from the core layer is a heat seal layer comprising a major fraction by weight of the heat seal layer of an amorphous polyester having at most about 10% crystallinity and being selected from the group consisting of a polyhydroxy acid, an amorphous aromatic copolyester which is the same as any amorphous aromatic copolyester of the polymeric barrier receiving layer and a blend thereof,
Dependencies are inferred from the claim text.