U.S. patent application number 13/924391 was filed with the patent office on 2013-12-26 for foam for footwear midsole and the like.
This patent application is currently assigned to COLUMBIA SPORTSWEAR NORTH AMERICA, INC.. The applicant listed for this patent is Columbia Sportswaer North America, Inc.. Invention is credited to Wei Yi Jiang, John F. Swigart.
Application Number | 20130340280 13/924391 |
Document ID | / |
Family ID | 49769453 |
Filed Date | 2013-12-26 |
United States Patent
Application |
20130340280 |
Kind Code |
A1 |
Swigart; John F. ; et
al. |
December 26, 2013 |
FOAM FOR FOOTWEAR MIDSOLE AND THE LIKE
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.
Inventors: |
Swigart; John F.; (Portland,
OR) ; Jiang; Wei Yi; (Zhuhai City, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Columbia Sportswaer North America, Inc. |
Portland |
OR |
US |
|
|
Assignee: |
COLUMBIA SPORTSWEAR NORTH AMERICA,
INC.
Portland
OR
|
Family ID: |
49769453 |
Appl. No.: |
13/924391 |
Filed: |
June 21, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61662826 |
Jun 21, 2012 |
|
|
|
Current U.S.
Class: |
36/43 ;
12/146R |
Current CPC
Class: |
A43B 13/125 20130101;
A43B 13/02 20130101; A43B 13/04 20130101 |
Class at
Publication: |
36/43 ;
12/146.R |
International
Class: |
A43B 13/02 20060101
A43B013/02 |
Claims
1. 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).
2. The high performance foam of claim 1, comprising: 15-25 PHR
polyolefin elastomer; 5-20 PHR olefin block copolymer; and 65-75
PHR EVA.
3. The high performance foam of claim 1, comprising 18-22 PHR
polyolefin elastomer.
4. The high performance foam of claim 1, comprising 9-16 PHR olefin
block copolymer.
5. The high performance foam of claim 1, comprising 68-72 PHR
EVA.
6. The high performance foam of claim 1, comprising: 18-22 PHR
polyolefin elastomer; 9-16 PHR olefin block copolymer; and 68-72
PHR EVA.
7. The high performance foam of claim 1, comprising: 20 PHR
polyolefin elastomer; 20 PHR olefin block copolymer; and 60 PHR
EVA.
8. The high performance foam of claim 1, comprising: 20 PHR
polyolefin elastomer; 10 PHR olefin block copolymer; and 70 PHR
EVA.
9. The high performance foam of claim 1, wherein the EVA is EVA
18%.
10. The high performance foam of claim 1, 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.
11. 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/cm.sup.3, and a melt index of 0.1-10 g/10 min.
12. The high performance foam of claim 11, wherein the
homogeneously branched, linear or substantially linear
ethylene/alpha-olefin polymer comprises a polyolefin elastomer
and/or an olefin block copolymer.
13. The high performance foam of claim 11, wherein the high
performance foam has a compression set of less than 45%.
14. The high performance foam of claim 11, wherein the high
performance foam has a resilience of greater than 45%.
15. The high performance foam of claim 11, wherein the high
performance foam has a bonding strength of greater than 25
N/cm.
16. The high performance foam of claim 11, 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.
17. 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.
18. The high performance foam of claim 17, comprising: 15-50 PHR
polyolefin.
19. The high performance foam of claim 17, wherein the polyolefin
comprises a polyolefin elastomer and/or an olefin block
copolymer.
20. 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.
21. The method of claim 20, wherein mixing the EVA, polyolefin
elastomer, and olefin block copolymer comprises mixing 65-75 PHR
EVA, 15-25 PHR polyolefin elastomer, and 5-20 PHR olefin block
copolymer.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to U.S. Provisional
Patent Application No. 61/662,826, filed Jun. 21, 2012, entitled
"Foam for Footwear Midsole and the Like," the entire disclosure of
which is hereby incorporated by reference in its entirety.
TECHNICAL FIELD
[0002] Embodiments herein relate to the field of foams for footwear
midsoles and other such applications.
BACKGROUND
[0003] Ethylene vinyl acetate (EVA) is commonly used as a polymer
in the foam chemistry of athletic footwear cushioned midsoles. EVA
is light, relatively inexpensive and has good cushioning properties
when new. However, the cushioning properties tend to diminish
quickly with use.
[0004] 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. But, 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.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] Embodiments will be readily understood by the following
detailed description in conjunction with the accompanying drawings
and the appended claims. Embodiments are illustrated by way of
example and not by way of limitation in the figures of the
accompanying drawings.
[0006] 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; and
[0007] FIG. 2 is a table illustrating several properties of the
high performance foam of FIG. 1, as compared to conventional EVA
foam, in accordance with various embodiments.
DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS
[0008] In the following detailed description, reference is made to
the accompanying drawings which form a part hereof, and in which
are shown by way of illustration embodiments that may be practiced.
It is to be understood that other embodiments may be utilized and
structural or logical changes may be made without departing from
the scope. Therefore, the following detailed description is not to
be taken in a limiting sense, and the scope of embodiments is
defined by the appended claims and their equivalents.
[0009] Various operations may be described as multiple discrete
operations in turn, in a manner that may be helpful in
understanding embodiments; however, the order of description should
not be construed to imply that these operations are order
dependent.
[0010] 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 embodiments.
[0011] The terms "coupled" and "connected," along with their
derivatives, may be used. It should be understood that these terms
are not intended as synonyms for each other. Rather, in particular
embodiments, "connected" may be used to indicate that two or more
elements are in direct physical contact with each other. "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.
[0012] For the purposes of the description, a phrase in the form
"A/B" or in the form "A and/or B" means (A), (B), or (A and B). For
the purposes of the description, 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). For the purposes of the description, a phrase
in the form "(A)B" means (B) or (AB) that is, A is an optional
element.
[0013] The description may use the terms "embodiment" or
"embodiments," which may each refer to one or more of the same or
different embodiments. Furthermore, the terms "comprising,"
"including," "having," and the like, as used with respect to
embodiments, are synonymous, and are generally intended as "open"
terms (e.g., the term "including" should be interpreted as
"including but not limited to," the term "having" should be
interpreted as "having at least," the term "includes" should be
interpreted as "includes but is not limited to," etc.).
[0014] With respect to the use of any plural and/or singular terms
herein, those having skill in the art can translate from the plural
to the singular and/or from the singular to the plural as is
appropriate to the context and/or application. The various
singular/plural permutations may be expressly set forth herein for
sake of clarity.
[0015] Embodiments herein provide high performance foam
formulations and processing methods that address issues with
traditional 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.
[0016] In various embodiments, 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. In various embodiments, 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.
[0017] In various embodiments, 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., DOWLEX.TM. brand LLDPE, made
by The Dow Chemical Company, Midland, Mich.), and ultra low linear
density polyethylene (ULDPE; e.g., ATTANE.TM. brand ULDPE,
manufactured by The Dow Chemical Company), etc., homogeneously
branched, linear ethylene/alpha-olefin copolymers (e.g., TAFMER.TM.
brand copolymer, manufactured by Mitsui PetroChemicals Company
Limited, and EXACT.TM. brand copolymer, manufactured by Exxon
Chemical Company), homogeneously branched, substantially linear
ethylene/alpha-olefin polymers (e.g., AFFINITY.TM., ENGAGE.TM., and
INFUSE.TM. brand polymers, manufactured by The Dow Chemical
Company), and high pressure, free radical polymerized ethylene
copolymers, such as EAA (e.g., PRIMACOR.TM. polymer, manufactured
by The Dow Chemical Company) and EVA (e.g., ESCORENE.TM. polymer,
manufactured by Exxon Chemical Company, and ELVAX.TM. polymer,
manufactured by E. I. du Pont de Nemours & Co.).
[0018] In particular embodiments, 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.sup.3, especially from about
0.85 to about 0.90 g/cm.sup.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. In various embodiments, 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. Although the
disclosed high performance foams are typically described as
including EVA, one of skill in the art will appreciate that in some
embodiments, EAA (containing from about 0.5 to about 25 wt %
derived from acrylic acid) and similar ethylenically unsaturated
carboxylic acid containing polymers also may be substituted.
[0019] As described herein, various embodiments of the disclosed
foams may include polyolefin elastomers and/or olefin block
copolymers. As used herein, the term "polyolefin elastomer" may
refer to a copolymer of ethylene and another alpha-olefin such as
butene or octene. In various embodiments, 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. In various embodiments,
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.
[0020] In various embodiments, 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
cyclopentadienyl ring structures to form a sterically hindered
polymerization site. In various embodiments, 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.
[0021] As used herein, the term "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. In various
embodiments, because the alternating block types provide highly
differentiated material properties along the chain, the traditional
relationship of flexibility and heat resistance in the polymer may
be disrupted to a beneficial effect. The materials, meanwhile, may
provide improved compression set and elastic recovery properties
versus other polyolefin plastomers and elastomers. In various
embodiments, olefin block copolymers may have both the flexibility
of polyolefin plastomers and elastomers and the heat resistance of
high density polyethylene.
[0022] As described above, in various embodiments, the high
performance foams may contain a mixture of EVA, polyolefin
elastomer (e.g., ENGAGE.TM.), and/or olefin block copolymer (e.g.,
INFUSE.TM.). In various embodiments, this mixture may produce a
high-performance foam that has an increased resilience compared to
traditional EVA foams. For example, in various embodiments, 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. In some embodiments, 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.
[0023] In various embodiments, the high performance foams also may
have reduced compression set when compared to traditional EVA
foams. For example, in various embodiments, 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. In various embodiments, 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.
[0024] In various embodiments, the high performance foams also may
have a reduced shrinkage rate, as compared to EVA foams. For
example, in various embodiments, 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.degree. 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.degree. C. for 24 hours before
length and width are measured.
[0025] 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. In the specific, non-limiting example illustrated in
FIG. 1, 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., ENGAGE.TM.) (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.,
INFUSE.TM.) (for instance, about 7-18 PHR, about 9-16 PHR, or about
11-14 PHR). As used herein, 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. For example, a foam that contains 350 g of
polyolefin elastomer and 650 g of EVA has a total "resin" weight of
1000 g, with polyolefin elastomer at 35 PHR and EVA at 65 PHR. As
used herein, 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.
[0026] In various embodiments, a high performance foam in
accordance with the present disclosure also may include small
amounts of pigments, fillers, blowing agents, and/or crosslinking
agents. For example, in one specific, non-limiting example, 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 TiO.sub.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).
[0027] As further illustrated in FIG. 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., ENGAGE.TM.,
for example ENGAGE.TM. 8200), and about 10 PHR of olefin block
copolymer (e.g., INFUSE.TM., such as INFUSE.TM. 9107). In another
specific, non-limiting example, 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
TiO.sub.2, about 2.5 PHR of blowing agent, and/or about 0.5 PHR of
DCP (crosslinker). In some embodiments, up to about 20 PHR of
olefin block copolymer (e.g., INFUSE.TM.) may be used. For example,
in another specific, non-limiting embodiment, a high performance
foam may include about 70 PHR of EVA, about 10 PHR of a polyolefin
elastomer (e.g., ENGAGE.TM.), and about 20 PHR of olefin block
copolymer (e.g., INFUSE.TM.). Another specific, non-limiting
embodiment may include about 60 PHR of EVA, about 20 PHR of
polyolefin elastomer (e.g., ENGAGE.TM.) and about 20 PHR of olefin
block copolymer (e.g., INFUSE.TM.). In some embodiments, the
stiffness and/or other performance elements of the footwear may be
varied in order to suit a particular application. For example, to
increase rebound, the amount of olefin block copolymer (e.g.,
INFUSE.TM.) in the formula may be increased, whereas if a stiffer
midsole is desired, a harder EVA and/or olefin block copolymer
(e.g., INFUSE.TM.) formulation may be selected.
[0028] FIG. 2 is a table illustrating several properties of the
high performance foam of FIG. 1, as compared to conventional EVA
foam, in accordance with various embodiments. In various
embodiments, 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. In the specific, non-limiting example illustrated
in FIG. 2, the high performance foam formulation produces a foam
with characteristics that are superior to those of traditional EVA
foams. For example, the illustrated foam has a hardness (Asker C)
of 53, versus 55 for EVA foam; a density of 0.22 g/cm.sup.3, versus
0.23 g/cm.sup.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.sup.2 versus 30 kg/cm.sup.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 compression set of 43%, as
compared to a compression set of 55% for EVA foam, and the
illustrated foam has a shrinkage rate of 0.8%, versus 1.2% for EVA
foam.
[0029] Although the exemplary foams illustrated in FIGS. 1 and 2
include more than one polyolefin, one of skill in the art will
appreciate that single polyolefins may be used. For instance, in
one example, a high performance foam may include 25-50 PHR or more
polyolefin elastomer (e.g., ENGAGE.TM.), and no olefin block
copolymer (e.g., INFUSE.TM.). Similarly, in another example, a high
performance foam may include 25-50 PHR or even more of olefin block
copolymer (e.g., INFUSE.TM.), and no polyolefin elastomer (e.g.,
ENGAGE.TM.)
[0030] Although certain embodiments have been illustrated and
described herein, it will be appreciated by those of ordinary skill
in the art that a wide variety of alternate and/or equivalent
embodiments or implementations calculated to achieve the same
purposes may be substituted for the embodiments shown and described
without departing from the scope. Those with skill in the art will
readily appreciate that embodiments may be implemented in a very
wide variety of ways. This application is intended to cover any
adaptations or variations of the embodiments discussed herein.
Therefore, it is manifestly intended that embodiments be limited
only by the claims and the equivalents thereof.
* * * * *