Foam for footwear midsole and the like
AssigneeColumbia Sportswear North America, Inc.
InventorsJohn F. Swigart, Wei Yi Jiang
Life of this patent
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Abstract
Embodiments herein provide high performance foam formulations and processing methods that address issues with traditional ethylene vinyl acetate (EVA) foams. In various embodiments, when used in midsoles, the high performance foam formulations may provide superior impact energy absorption per given load during compression, improved energy recovery during expansion, and reduced compression set over repeated impact cycles. In various embodiments, the high performance foam formulations may include a mixture of no more than about 75 PHR EVA foam and at least 15 PHR polyolefin foam.
Claims21
A high performance foam for a midsole comprising:
- at least 15 parts per hundred resin (PHR) polyolefin elastomer;
- at least 5 PHR olefin block copolymer;
- and
- no more than 75 PHR ethylene vinyl acetate (EVA).
A high performance foam for a midsole, comprising:
- ethylene vinyl acetate (EVA);
- and
- 25-50 PHR homogeneously branched, linear or substantially linear ethylene/alpha-olefin polymer, wherein the homogeneously branched, linear or substantially linear ethylene/alpha-olefin polymer has a density of from 0.85-0.92 g/cm3, and a melt index of 0.1-10 g/10 min.
A high performance foam for a midsole comprising:
- at least 15 PHR polyolefin;
- and
- no more than 75 PHR ethylene vinyl acetate (EVA), wherein the high performance foam has a compression set of less than 45%, a resilience of greater than 45%, and a bonding strength of greater than 25 N/cm.
A method of making a high performance midsole comprising:
- mixing ethylene vinyl acetate (EVA), a polyolefin elastomer, and an olefin block copolymer to form an EVA/polyolefin mixture;
- and
- compression molding the EVA polyolefin mixture to form the midsole.
Dependencies are inferred from the claim text.