Patent ID: 7655728
Filing Date: 2010-02-02
Classification: B29B,B29C,C08L

Abstract:
1. A method for preparing a thermoplastic vulcanizate within a ring extruder having a length and a diameter defined by a length to diameter ratio of 15-100, the extruder including at least three screws having a length and including intermeshing elements disposed along the length to achieve a screw profile that has 3 to 17 meshes per unit of length to diameter of the extruder, and where the extruder includes at least two screws including blocking elements disposed in the first ¼ portion of the length of the extruder defined from the feed throat of the extruder to prevent cross-over of material and thereby create at least two mixing portions within the first ¼ portion of the extruder, the method comprising: i. charging thermoplastic polymer to the extruder; ii. charging vulcanizable polymer to the extruder; iii. charging curative for the vulcanizable polymer to the extruder; iv. melt mixing the thermoplastic polymer and curative within a first mixing portion of the first ¼ portion of the length of the extruder; v. masticating the vulcanizable polymer within a second mixing portion of the first ¼ portion of the length of the extruder, where said step of melt mixing the thermoplastic polymer and curative and said step of masticating the vulcanizable polymer occurs simultaneously; vi. preventing the cross-over of the curative and thermoplastic polymer contained in the first mixing portion to the vulcanizable polymer contained in the second mixing portion for at least a portion of the first ¼ portion of the length of the extruder by using the blocking elements; vii. melt mixing the curative, thermoplastic polymer, and vulcanizable polymer after said step vi and viii. dynamically vulcanizing the vulcanizable polymer after said step vi to thereby form a thermoplastic vulcanizate.