Gel reduction in blends of thermoplastic polyurethane and hydroxyl functional polymers
AssigneeNIKE, Inc.
InventorsRichard L Watkins, Yihua Chang
Life of this patent
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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.
Claims29
A composition comprising:
- a first component comprising thermoplastic polyurethane;
- a second component comprising a hydroxyl-functional copolymer;
- and
- a third component comprising a gel reducing additive having a molecular weight of less than the molecular weight of the hydroxyl-functional copolymer;
- 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,
- wherein the gel reducing additive is selected from the group consisting of compounds with at least one hydroxyl group, 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.
A method for preparing a sheet comprising a blend of thermoplastic polyurethane and at least one hydroxyl-functional copolymer, comprising the steps of:
- combining a first component comprising at least one thermoplastic polyurethane, a second component comprising a hydroxyl-functional copolymer, and a third component comprising a gel reducing additive;
- applying thermal energy, mechanical energy, or both, to the combination of thermoplastic polyurethane, ethylene vinyl alcohol copolymer, and gel reducing additive to produce a blend;
- and
- producing a sheet from the blend,
- 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 has a molecular weight lower than that of the hydroxyl-functional copolymer and is selected from the group consisting of compounds with at least one hydroxyl group, 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.
A multilayer composite comprising a plurality of flexible layers, wherein at least one of the flexible layers is the product of forming a sheet from a blend comprising thermoplastic polyurethane, hydroxyl-functional copolymer, and 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 has a lower molecular weight than that of the hydroxyl-functional copolymer, and contains at least one functional group that is reactive with isocyanate.
Dependencies are inferred from the claim text.