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AssigneeKimberly-Clark Worldwide, Inc.
InventorsNeil T. Scholl, Ryan J. McEneany, Thomas A. Eby, Vasily A. Topolkaraev
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A thermoplastic composition that contains a rigid renewable polyester and has a voided structure and low density is provided. To achieve such a structure, the renewable polyester is blended with a polymeric toughening additive to form a precursor material in which the toughening additive can be dispersed as discrete physical domains within a continuous matrix of the renewable polyester. The precursor material is thereafter stretched or drawn at a temperature below the glass transition temperature of the polyester (i.e., “cold drawn”). This creates a network of voids located adjacent to the discrete domains, which as a result of their proximal location, can form a bridge between the boundaries of the voids and act as internal structural “hinges” that help stabilize the network and increase its ability to dissipate energy. The present inventors have also discovered that the voids can be distributed in a substantially homogeneous fashion throughout the composition.
A thermoplastic composition comprising at least one rigid renewable polyester having a glass transition temperature of about 0° C. or more and at least one polymeric toughening additive, wherein the thermoplastic composition has a morphology in which a plurality of discrete primary domains and voids are dispersed within a continuous phase, the domains containing the polymeric toughening additive and the continuous phase containing the renewable polyester, wherein the thermoplastic composition has a density of about 1.4 grams per cubic centimeter or less, and wherein the average percent volume of the composition that is occupied by the voids is from about 20% to about 80% per cubic centimeter.
A method for forming a low density thermoplastic composition for use in a molded article, the method comprising:
Dependencies are inferred from the claim text.