Classifications

• • A—HUMAN NECESSITIES
  • A43—FOOTWEAR
  • A43B—CHARACTERISTIC FEATURES OF FOOTWEAR; PARTS OF FOOTWEAR
  • A43B13/00—Soles; Sole-and-heel integral units
  • A43B13/02—Soles; Sole-and-heel integral units characterised by the material
  • A43B13/12—Soles with several layers of different materials
  • A43B13/125—Soles with several layers of different materials characterised by the midsole or middle layer
• • A—HUMAN NECESSITIES
  • A43—FOOTWEAR
  • A43B—CHARACTERISTIC FEATURES OF FOOTWEAR; PARTS OF FOOTWEAR
  • A43B13/00—Soles; Sole-and-heel integral units
  • A43B13/02—Soles; Sole-and-heel integral units characterised by the material
  • A43B13/04—Plastics, rubber or vulcanised fibre
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/0061—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof characterized by the use of several polymeric components
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
  • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
  • C08J2323/04—Homopolymers or copolymers of ethene
  • C08J2323/08—Copolymers of ethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2400/00—Characterised by the use of unspecified polymers
  • C08J2400/26—Elastomers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2453/00—Characterised by the use of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2453/00—Characterised by the use of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives of such polymers
  • C08J2453/02—Characterised by the use of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives of such polymers of vinyl aromatic monomers and conjugated dienes

Definitions

• Embodiments herein relate to the field of foams for footwear midsoles and other such applications.
• EVA Ethylene vinyl acetate
• Some footwear manufacturers blend more durable polymers (e.g., polyolefin elastomer) with EVA or replace EVA altogether in order to reduce compression set and enhance resiliency and durability.
• polyolefin elastomer elastomeric foams
• certain elastomeric foams can be expensive and the ranges of performance properties are somewhat limited.
• Polyolefins have excellent chemical resistance, which renders them difficult to bond with solvent cements, and the surfaces of polyolefin foams have a greater tendency to become oily to the touch.
• Some manufacturers address this by limiting the amount of polyolefin blended throughout the midsole (typically less than 15%).
• Other manufacturers apply the polyolefinic foam in a localized fashion, such as under the center of the heel, and then use standard foam throughout the rest of the midsole.
• Figure 1 is a table illustrating the composition of one specific, non- limiting example of a high performance foam as compared to conventional EVA foam, in accordance with various embodiments.
• Figure 2 is a table illustrating several properties of the high
• the description may use perspective-based descriptions such as up/down, back/front, and top/bottom. Such descriptions are merely used to facilitate the discussion and are not intended to restrict the application of disclosed
• Coupled may mean that two or more elements are in direct physical contact. However, “coupled” may also mean that two or more elements are not in direct contact with each other, but yet still cooperate or interact with each other.
• a phrase in the form "A B” or in the form “A and/or B” means (A), (B), or (A and B).
• a phrase in the form "at least one of A, B, and C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).
• a phrase in the form "(A)B” means (B) or (AB) that is, A is an optional element.
• Embodiments herein provide high performance foam formulations and processing methods that address issues with traditional EVA foams.
• the high performance foam formulations when used in midsoles, may provide superior impact energy absorption per given load during compression, improved energy recovery during expansion, and reduced compression set over repeated impact cycles.
• the high performance foam formulations may utilize block copolymers to achieve stability. Certain embodiments may use greater concentrations of polyolefins as compared to traditional foams, without degrading the ability to bond adjoining footwear parts. For example, in various embodiments using such high performance foams, an entire midsole may be formed using a greater percentage of polyolefin compared to known foams, and yet, in embodiments, may remain easy to bond, provide an oil-free feel, and/or deliver superior cushioning performance and durability.
• one or more polyolefin elastomers and/or olefin block copolymers may be combined with ethylene vinyl acetate (EVA) to create a foam having greater resilience, greater tensile strength, reduced shrinkage, reduced compression set, and/or improved bonding, as compared to EVA alone and/or other EVA polyolefin foams.
• EVA ethylene vinyl acetate
• suitable olefinic polymers for the production of the high performance foam formulations disclosed herein may include linear high density polyethylene (HDPE), linear low density polyethylene (LLDPE; e.g.,
• DOWLEXTM brand LLDPE made by The Dow Chemical Company, Midland, M l
• ultra low linear density polyethylene ULDPE
• homogeneously branched, linear ethylene/alpha-olefin copolymers e.g., TAFMERTM brand copolymer, manufactured by Mitsui Petrochemicals Company Limited, and EXACTTM brand copolymer, manufactured by Exxon Chemical Company
• homogeneously branched, substantially linear ethylene/alpha-olefin polymers e.g., AFFINITYTM, ENGAGETM , and INFUSETM brand polymers, manufactured by The Dow Chemical Company
• high pressure, free radical polymerized ethylene copolymers such as EAA (e.g., PRIMACORTM polymer, manufactured by The Dow Chemical Company) and EVA (e.g., ESCORENETM polymer, manufactured by Exxon Chemical Company, and EL
• the olefinic polymers may include homogeneously branched linear and substantially linear ethylene copolymers with a density (measured in accordance with ASTM D-792) from about 0.85 to about 0.92 g/cm 3 , especially from about 0.85 to about 0.90 g/cm 3 and a melt index (measured in accordance with ASTM D-1238 (190/2.16)) from about 0.1 to about 10 g/10 minutes.
• the EVA may contain from about 0.5 to about 50 wt% derived from vinyl acetate, and may include one or more EVA polymers having a melt index (ASTM D-1238 (190/2.16)) from about 0.5 to about 10 g/10 minutes.
• various embodiments of the disclosed foams may include polyolefin elastomers and/or olefin block copolymers.
• polyolefin elastomer may refer to a copolymer of ethylene and another alpha- olefin such as butene or octene.
• a metallocene catalyst may be used to selectively polymerize ethylene and comonomer sequences, and increasing the comonomer content may produce polymers with higher elasticity as the comonomer incorporation disrupts the polyethylene crystallinity.
• the molecular weight of the copolymer may help determine the processing characteristics and end-use performance properties of the polyolefin elastomer, with higher molecular weights providing enhanced polymer toughness.
• polyolefin copolymers may be produced using refined metallocene catalysts often referred to as single-site or constrained geometry catalysts. These catalysts may have a constrained transition metal (generally a Group 4B metal such as Ti, Zr, or Hf) sandwiched between one or more constrained transition metal (generally a Group 4B metal such as Ti, Zr, or Hf) sandwiched between one or more constrained transition metal (generally a Group 4B metal such as Ti, Zr, or Hf) sandwiched between one or more
• a constrained transition metal generally a Group 4B metal such as Ti, Zr, or Hf
• this catalyst may provide a single polymerization site instead of the multiple sites of conventional catalysts, and may provide the capability to tailor the molecular architecture of ethylene copolymers.
• olefin block copolymer may refer to a polymer having chains with alternating blocks of “hard” (highly rigid) and “soft” (highly elastomeric) segments that are created and assembled via a shuttling process.
• hard highly rigid
• soft highly elastomeric
• olefin block copolymers may have both the flexibility of polyolefin plastomers and elastomers and the heat resistance of high density polyethylene.
• the high performance foams may contain a mixture of EVA, polyolefin elastomer (e.g., ENGAGETM), and/or olefin block copolymer (e.g., INFUSETM).
• this mixture may produce a high-performance foam that has an increased resilience compared to traditional EVA foams.
• the high performance foam may have a resilience of 48-52% (for example, using the DIN 53512 test for determining the rebound resilience of rubber using the Schob pendulum published by the International Organization for Standardization (IOS); standard 45% min.), as compared to a resilience of about 45% (standard 40% min.) for EVA foam.
• resilience may refer to the percentage of energy used to compress a foam that is recovered as mechanical work during expansion of the foam. In some embodiments, resilience may be measured by dropping a missile from a known height onto the foam below, then measuring how high the missile rebounds.
• the high performance foams also may have reduced compression set when compared to traditional EVA foams.
• the compression set of the high performance foam may have a maximum of about 45%, whereas EVA foam may have a maximum of about 60% using the ASTM D-395 (B) Standard Test Method for Rubber Property - Compression Set, or the SATRA TM64 Compression Set - Constant Stress Method published by SATRA Technology Centre.
• compression set may be measured as a percentage of original thickness of the sample, and may refer to the degree to which a sample loses some of its original dimensions due to permanent deformation.
• the high performance foams also may have a reduced shrinkage rate, as compared to EVA foams.
• the shrinkage rate of the high performance foam may be about 1 % (70 Asker C, one hour), whereas EVA foam may have a shrinkage rate of about 1 .5% (Comparable Example 1 : 70 Asker C, 15 minutes; Comparable Example 2: 50 Asker C, 24 hours).
• Shrinkage may be measured in a variety of ways. In one example, a specimen may be heated to 70°C for 15 minutes, cooled to room temperature, and the resulting length and width are compared to the starting dimensions. In another example, a specimen may be heated to 50°C for 24 hours before length and width are measured.
• FIG. 1 is a table illustrating the composition of one specific, non- limiting example of a high performance foam as compared to conventional EVA foam, in accordance with various embodiments.
• the high performance foam may include about 65-75 PHR (parts per hundred resin) of EVA (for instance, about 66-74 PHR, about 67-73 PHR, about 68-72 PHR, or about 69-71 PHR); about 15-25 PHR of a polyolefin elastomer (e.g., ENGAGETM) (for instance, about 16-24 PHR, about 17-23 PHR, about 18-22 PHR, or about 19-21 PHR); and about 5-20 PHR of an olefin block copolymer (e.g., INFUSETM) (for instance, about 7-18 PHR, about 9-16 PHR, or about 1 1 -14 PHR).
• a polyolefin elastomer e.g., ENGAGETM
• INFUSETM an olefin block
• the terms “PHR” and “parts per hundred resin” refer to the parts in weight of the referenced component in relation to the total weight of the plastics and other polymers in the formulation.
• a foam that contains 350g of polyolefin elastomer and 650g of EVA has a total "resin" weight of 1000g, with polyolefin elastomer at 35 PHR and EVA at 65 PHR.
• the "resin” does not include additional ingredients, such as pigments, fillers, blowing agents, and/or crosslinking agents, and varying the amounts of these ingredients does not change the total resin weight for the purpose of calculating PHR.
• a high performance foam in accordance with the present disclosure also may include small amounts of pigments, fillers, blowing agents, and/or crosslinking agents.
• a high performance form in accordance with the present disclosure may include about 1 .25 to about 1 .75 PHR of ZnO (for example, about 1 .3-1 .6 PHR, or about 1 .1 -1 .4 PHR), about 0.3-0.7 PHR STA (stearic acid) (for example, about 0.4- 0.6 PHR), about 5-15 PHR of filler, about 1 .25-1 .75 PHR of Ti0 2 (for example, about 1 .4-1 .6 PHR), about 2.25-2.75 PHR of blowing agent (for example, about 2.4-2.6 PHR), and/or about 0.4-0.7 PHR of the crosslinker DCP (dicumyl peroxide; for example, about 0.5 to about 0.6 PHR).
• ZnO for example, about 1 .3-1 .6 PHR, or about 1
• a high performance foam in accordance with the present disclosure may include about 70 PHR of EVA 18%, about 20 PHR of a polyolefin elastomer (e.g., ENGAGETM, for example ENGAGETM 8200), and about 10 PHR of olefin block copolymer (e.g., INFUSETM, such as INFUSETM 9107).
• a polyolefin elastomer e.g., ENGAGETM, for example ENGAGETM 8200
• olefin block copolymer e.g., INFUSETM, such as INFUSETM 9107
• a high performance foam in accordance with the present disclosure also may include about 1 .5 PHR of ZnO, about 0.5 STA, about 10 PHR of filler, about 1 .5 PHR of Ti0 2 , about 2.5 PHR of blowing agent, and/or about 0.5 PHR of DCP (crosslinker).
• DCP crosslinker
• a high performance foam may include about 70 PHR of EVA, about 10 PHR of a polyolefin elastomer (e.g., ENGAGETM), and about 20 PHR of olefin block copolymer (e.g., INFUSETM).
• a polyolefin elastomer e.g., ENGAGETM
• olefin block copolymer e.g., INFUSETM
• Another specific, non-limiting embodiment may include about 60 PHR of EVA, about 20 PHR of polyolefin elastomer (e.g., ENGAGETM), and about 20 PHR of olefin block copolymer (e.g., INFUSETM).
• the stiffness and/or other performance elements of the footwear may be varied in order to suit a particular application.
• the amount of olefin block copolymer (e.g., INFUSETM) in the formula may be increased, whereas if a stiffer midsole is desired, a harder EVA and/or olefin block copolymer (e.g., INFUSE ) formulation may be selected.
• Figure 2 is a table illustrating several properties of the high
• the polyolefins selected and the amounts used in the high performance foams may be varied in order to obtain a desired resilience, density, hardness, tensile strength, shrinkage, or other properties.
• the high performance foam formulation produces a foam with characteristics that are superior to those of traditional EVA foams.
• the illustrated foam has a hardness (Asker C) of 53, versus 55 for EVA foam; a density of 0.22 g/cm 3 , versus 0.23 g/cm 3 for EVA foam; and a resilience of 48% versus 43% for EVA foam.
• the illustrated foam also has a tensile strength of 31 .1 kg/cm 2 versus 30 kg/cm 2 for EVA foam, and both the illustrated foam and the EVA foam have a bonding strength with a substrate of greater than 25 N/cm, both pass the Ross Flex cracking test (e.g., ASTM D1052) with greater than 50,000 times with no damage, the illustrated foam has a
• a high performance foam may include 25-50 PHR or more polyolefin elastomer (e.g., ENGAGETM), and no olefin block copolymer (e.g., INFUSETM).
• a high performance foam may include 25-50 PHR or even more of olefin block copolymer (e.g.,

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Citations (6)

• 2013
  • 2013-06-21 WO PCT/US2013/047167 patent/WO2013192581A1/fr not_active Ceased
  • 2013-06-21 CN CN201380033063.0A patent/CN104684432A/zh active Pending
  • 2013-06-21 US US13/924,391 patent/US20130340280A1/en not_active Abandoned

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