Patent Number: 6,169,143

Title: Elevated temperature dimensionally stable, impact modified polyester with low gas permeability

Abstract: Polyester composition with improved impact properties, improved oxygen permeability and improved dimensional shrinkage during heating. Impact modifiers are dissolved into a molten polyester to form a eutectic alloy. On slow cooling, the eutectic alloy of the invention freezes to form a mixture of particles of the impact modifier embedded in a matrix of the polyester. By controlling the solidification of the melt, the size and distribution of the precipitates from the melt can be controlled, which allows control of the mechanical properties. The precipitation can also be controlled either by homogenous nucleation or by heterogeneous nucleation through the addition of a nucleating agent or the introduction of a suitable surface for nucleation. The invention also provides a process of manufacturing the above polyester, an article comprising this polyester and a process for making this article. The crystalline polyester article is useful as a container for microwavable, ovenable and/or frozen foods, and has improved gas barrier properties, impact strength, and post-mold dimensional stability between -60.degree. C. and 200.degree. C.

Inventors: Dalgewicz, III; Edward J. (Millstone, NJ), Bond; John (Pittsburgh, PA), Freundlich; Richard (Plainsboro, NJ)

Assignee: Lawson Mardon Thermaplate Corporation

International Classification: B29C 49/00 (20060101); B65D 81/34 (20060101); C08G 63/88 (20060101); C08G 63/00 (20060101); C08L 67/02 (20060101); C08L 67/00 (20060101); B29C 71/00 (20060101); C08L 101/00 (20060101); C08G 063/48 ()

Expiration Date: 01/02/2018