Gel reduction in blends of thermoplastic polyurethane and hydroxyl functional polymers
AssigneeNIKE, Inc.
InventorsRichard L Watkins, Yihua Chang
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Abstract
Gas barrier layers and composites contain a low gel sheet produced from a composition containing a thermoplastic polyurethane (TPU), a hydroxyl functional copolymer, and a gel reducing additive. The gel reducing additive has functional groups that can react with isocyanate groups to reduce gel formation during the processing of blends of urethane containing polymers and hydroxyl functional polymers. Multilayer composites containing the low gel sheets can be made into inflatable membranes for containing an inflationary gas. In a particularly preferred embodiment, the membranes are used as bladders of cushioning devices in the soles of shoes, particularly athletic shoes.
Claims22
A shoe, comprising an upper and a sole, wherein the sole comprises one or more inflatable membranes for containing an inflationary gas, wherein at least one of the membranes comprises a multilayer composite, wherein the composite comprises at least one flexible layer comprising a low gel sheet formed from a composition comprising a blend of thermoplastic polyurethane, hydroxyl functional copolymer, and a gel reducing additive, wherein the composition comprises 0.05% to 20% by weight of the gel reducing additive,
- wherein the hydroxyl-functional copolymer comprises
- a) a polymer having 10 mole percent or more of repeating units of structure
- wherein n is 1, R1 and R2 are independently hydrogen, methyl, or ethyl, and R3 is hydrogen or C1-3 alkyl, or
- b) a copolymer of ethylene and vinyl alcohol with 25-60 mol % ethylene, and
- wherein the gel reducing additive is selected from the group consisting of compounds with two or more hydroxyl groups, compounds with at least one primary amino group, compounds with at least one secondary amino group, compounds with at least one carboxyl group, and compounds with at least one carboxylic anhydride group.
Dependencies are inferred from the claim text.