Stock material or miscellaneous articles – Composite – Of addition polymer from unsaturated monomers
Reexamination Certificate
2005-04-26
2008-08-19
Ahmed, Sheeba (Department: 1794)
Stock material or miscellaneous articles
Composite
Of addition polymer from unsaturated monomers
C428S034600, C428S516000, C264S479000
Reexamination Certificate
active
07413812
ABSTRACT:
A thermoformed polypropylene article, or sheet for preparing such articles, is formed from a layer of substantially syndiotactic polypropylene and a thin outer layer of substantially isotactic polypropylene that is joined to the layer of syndiotactic polypropylene. At least one of the layers is a non-oriented layer. Two layers of isotactic polypropylene may be used with the layer of syndiotactic polypropylene, so that the syndiotactic polypropylene is sandwiched between the two layers of isotactic polypropylene. The use of the isotactic polypropylene enhances the processability of the syndiotactic polypropylene, which is oftentimes difficult to process because of its lower melting point and slow solidification rate. Because the sheet is comprised predominantly of syndiotactic polypropylene, utilizing only thin outer layers of isotactic polypropylene, it has better transparency and higher impact strength than those conventional articles formed entirely of isotactic polypropylene.
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Pitt Supaphol et al.;Thermal Properties and Isothermal Crystalization of Syndiotactic Polypropylenes: Differential Scanning Calorimetry and Overall Crystallization Kinetics, Journal of Applied Polymer Science, vol. 75, pp. 444-459 (2000).
Ahmed Sheeba
Fina Technology, Inc.
Kilpatrick-Lee Diane L.
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