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Film-forming composition |
| T955009 |
Film-forming composition
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| Inventor: |
Lansbury, et al. |
| Date Issued: |
February 1, 1977 |
| Application: |
05/689,545 |
| Filed: |
May 24, 1976 |
| Inventors: |
Heggs; Thomas Geoffrey (Welwyn, Hertfordshire, EN)
Lansbury; Robert Clive (St. Albans, Hertfordshire, EN)
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| U.S. Class: |
264/211.12; 264/DIG.57; 426/127; 428/515; 428/520; 428/910; 525/240 |
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| Abstract: |
There is disclosed a thermoplastic, film-forming composition comprising a blend ofA. a propylene-ethylene copolymer, the propylene content of the copolymer being from 95 to 99.75% by weight of the copolymer, andB. a polymer of an alpha-olefin of 4 to 10 carbon atoms copolymerized with from 0 to 10% by weight of the copolymer of an alpha-olefin of 2 to 10 carbon atoms,The alpha-olefin polymer constituting from 41 to 90% by weight of the composition.The propylene-ethylene copolymer preferably contains from 2 to 4% by weight of ethylene, and preferably, in granular form, exhibits a Melt Flow Index of from 10 to 200 g/10 minutes, measured according to ASTM/D1238-65T (Condition N).The alpha-olefin component of the blend is suitably a polymer, preferably a homo-polymer, of butene-1, and suitably has a Melt Flow Index, by the aforementioned test, of less than 50 g/10 minutes, preferably between 5 and 40 g/10 minutes.To ensure the production of films having acceptable optical characteristics, the alpha-olefin component preferably comprises from 45 to 65% by weight of the composition. Additives, such as pigments, anti-static agents, and the like, conventionally employed in film production, may be included in the composition, if desired.The composition is suitably employed for the production of self-supporting films, and is particularly useful as a heat-sealable surface layer of a coextruded, biaxially oriented, multiple-layer film having a substrate layer of a propylene homo- or co-polymer. Such films are heat-sealable at comparatively low temperatures to provide strong heat seals, and are particularly suitable for the packaging of foodstuffs, and the like. |
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