Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVED LACES FOR USE WITH FOOTWEAR,
SPORTS EQUIPMENT AND THE LIKE
FIELD OF THE INVENTION
The present invention relates to improved laces for use with footwear, sports
equipment and the like.
BACKGROUND OF THE INVENTION
Laces for footwear, such as shoes and boots, and for sports equipment, such
as skates, rollerblades, boxing gloves and sports padding, are typically made
from
conventional fibers - cotton, nylon or polyester. One problem with these prior
art
laces is that they wear out as a result of abrasion and break frequently,
usually at
inopportune moments and thus render the associated footwear or sports
equipment
inoperable. Laces made of aramid fiber, such as that sold under the trademark
KEVLAR by DuPont, have recently been made available, but testing and
experience
has shown that these do not last even as long as those made of the traditional
materials. Accordingly, it is desirable to use laces that are significantly
stronger and
resistant to wear and are less prone to breakage than the laces of the prior
art.
SUMMARY OF THE INVENTION
The above shortcomings may be addressed by providing, in accordance with
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the invention, laces for footwear or sporting equipment comprised of yarns
made
from liquid crystal polymer (LCP) fibers.
In another aspect, the present invention provides for the use LCP fiber in
laces
for footwear or sports equipment. In another aspect, the present invention
provides
methods of securing an item of footwear or sports equipment having eyelets
therein
for that purpose, the methods comprising providing laces comprised of LCP
fiber, and
threading the laces through the eyelets in a configuration that enables said
item to be
secured. In yet another aspect, the present invention provides methods of
manufacturing laces for footwear, sporting equipment and the like, comprising
providing yarns comprised of liquid crystal polymer (LCP) fibers and weaving
said
yarns into a braid suitable for use in laces.
In preferred embodiments of the present invention, the laces comprise of
100% high-modulus multifilament yarn that is made from melt-spun liquid
crystal
polymer (LCP), also known as aromatic polyester, such as that sold under the
trademark VECTRAN.
In alternative embodiments, of the present invention, the laces comprise
partially of liquid crystal polymer (LCP) fibers and partially of other
fibers. For
example, in such alternate embodiments, the amount of LCP fibers in the laces
by
percentage of total fibers may be in an amount from a minimum of 30%, 40%,
50%,
60%, or 70% to a maximum of 50%, 60%, 70%, 80%, 90% or 99%, wherein a range
may, for example, be selected from any of the foregoing minimum values in
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combination with any of the foregoing maximum values, or any value lesser
than,
greater than or in between, for example, 30% to 99%, 60% to 99% or 80% to 99%.
LCP fiber is a high-modulus fiber, meaning that it is stiffer in tension and
does
not stretch as much as conventional fibers. It was determined that LCP fiber
is very
resistant to abrasion, more than most conventional fibers. LCP fiber is also
much
stronger than the conventional fibers. As well, the greater tensile stiffness
and
strength of LCP fiber allows pulling the laces tighter. This is especially
advantageous
in sporting equipment where generally greater force is required to pull the
parts of the
equipment together.
The increased strength and reduced abrasion of laces made from LCP fiber
result in fewer breaks, increased reliability and longer lifetime of the
footwear or
sporting equipment.
The greater tensile stiffness of laces made from LCP fiber means that these
laces will stretch less as a person walks, runs, skates, etc. with the
associated
footwear or sports equipment. Repeated stretching and relaxing of conventional
laces causes the laces to move through the eyelets in the footwear or
equipment and
abrade against the eyelets as well as against other parts of the footwear or
equipment, or against the laces themselves. This abrasion leads to
deterioration and
breakage of the laces. It was determined that the laces made from LCP fiber do
not
stretch as much and thus are subjected to less abrasion and will last longer
than the
prior art laces.
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The greater tensile stiffness of laces made from LCP fiber also means that
after the LCP fiber laces are tied at a desired tightness, they will remain
tied at that
tightness. In contrast, conventional fiber laces stretch and loosen, and thus
require
frequent retightening.
These and other aspects, features and embodiments are set forth within this
application. The present invention comprises a variety of aspects, features
and
embodiments; such multiple aspects, features and embodiments can be combined
and permuted in any desired manner.
DETAILED DESCRIPTION
The present invention provides laces for footwear or sporting equipment
comprised of liquid crystal polymer (LCP) fibers. LCP fibers have much higher
tension stiffness than conventional fibers used in laces. They are also
significantly
stronger than conventional fibers. An example of liquid crystal polymer (LCP),
also
known as aromatic polyester, is the product produced and sold under the
trademark
VECTRAN by Kuraray America.
It was surprisingly discovered in laboratory performance tests on laces made
of LCP fiber and on commercially available laces made of polyester and aramid
fibers
(KEVLAR), that the LCP fiber laces lasted at least five times longer than the
best
polyester fiber laces, and about twenty times longer than the best aramid
fiber laces.
The LCP fiber laces in the tests were solid braid construction. In solid braid
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construction, all of the strand carriers on the braider move in the same
direction. A
strand moves under another, moves to the side in the interior of the rope,
comes
back to the surface, and goes under again. All of the strands on the surface
appear
aligned with the axis. Below the surface, the strands cross over to one side,
always
in the same direction.
In these tests, the laces were cycled back and forth through metal eyelets,
similar to those used in boots, shoes, and sporting equipment, with an applied
load of
2 lb (i.e. 907 g) weight until the laces failed. The average cycles to failure
for the
LCP fiber laces was 201,989 cycles, and these LCP laces significantly
outperformed
the polyester and aramid fiber laces.
The average cycles to failure for the best brand of polyester fiber laces was
37,802 cycles. Other brands of polyester fiber laces performed only to
averages of
10,593 cycles and 8,432 cycles. The best brand of all-aramid fiber laces
survived an
average of 9,518 cycles. Another brand of all-aramid fiber laces survived to
an
average of only 4,466 cycles. Another brand had only several strands of aramid
mixed with polyester fiber, and it survived 6,775 cycles. Yet another brand
which was
called aramid but actually had no aramid fiber and was made entirely of
polyester
fibers, survived an average of 7,380 cycles.
Table 1 summarizes information on the sources and characteristics of the
tested boot laces.
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TABLE 1
Label used in Boot Lace Type or Description Material Weight,
Charts herein Brand g/m
LCP LCP fiber small black firm VECTRAN 4.7
round braid
KEVLAR 1 gold KEVLAR flat braid, gold KEVLAR 6.4
KEVLAR 2 PROCARE Hiker large black hollo- Polyester sheath 6.3
KEVLAR lace braid sheath, Polyester core (no
multicolor solid-braid KEVLAR)
core
KEVLAR 3 Black & gold flat braid, black with KEVLAR and polyester 4.3
KEVLAR gold stripe
KEVLAR 4 BULL DOG small black round KEVLAR 2.9
KEVLAR braid
Polyester polyester lace brown small round polyester 7.4
braid sheath
COVINGTON COVINGTON brand brown and gold polyester sheath, cotton 6.8
lace round braid core
KIWI KIWI brand lace black and brown polyester sheath, 4.5
round braid green polypropylene core
core
Leather leather lace brown, square cut leather 5.4
The construction of the shoe laces varied. Several, including the LCP fiber
laces, were solid braid. Several were hollow braid sheath, with or without
core.
Several were flat braid. The PROCARE KEVLAR lace comprised a polyester hollow-
braid sheath and a solid-braid multi-color polyester core. There was actually
no
KEVLAR yarn in this product. The gold KEVLAR was a flat-braid construction of
KEVLAR strands. The black and gold KEVLAR was a flat-braid construction
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comprised of two gold KEVLAR strands and many black polyester strands.
The tests were conducted on a modification of the 4-station yarn-on-yarn
abrasion test machine. That test machine is usually used to conduct yarn-on-
yarn
abrasion tests in accordance with industry standards. The modified test
machine
was provided with 1/4 inch (6.35 mm) brass grommets, similar to those used in
boots,
inserted in holes drilled through aluminum angle bars. These bars were mounted
on
the four stations of the test machine. Each of the lace specimens was run
through the
brass grommet, and each lace specimen was pulled back and forth through the
grommet under an applied load of 2 lb (907g) with a stroke of 2 inches (50.8
mm) and
at a rate of one cycle per second. Cycles for each specimen were counted by
counters that shut off automatically when the lace failed or when it became so
damaged that it would be unusable.
With reference to the figures, Figure 1 is a chart of the performance test
results of the LCP fiber laces of the present invention against the four laces
that were
comprised of KEVLAR fibers (except in the case identified above which actually
contained no aramid fibers). Figure 2 is a chart of the performance test
results of the
LCP fiber laces of the present invention against four other laces comprised of
conventional fibers.
These performance tests demonstrated that, surprisingly, the LCP fiber laces
have a service life that is at least five times longer than the best polyester
fiber laces
and about twenty times longer than the best aramid fiber laces.
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In these tests, the principal cause of wear and failure of the laces was
determined to be internal abrasion resulting from fibers rubbing against each
other
when the lace flexed as it moved around the radius of the metal eyelet. Both
polyester and LCP fiber yarns are very resistant to this type of internal
wear. Aramid
is much less resistant to this type of wear.
Each of the laces in these tests were subjected to the same 2 inch (50.8 mm)
stroke around the radius of the metal eyelet. It was discovered that because
LCP
fiber laces exhibit virtually no stretch when compared to polyester and other
conventional fiber laces, they would not move as much around the radius of the
metal
grommet, and they would suffer even less internal abrasion. Thus, when used in
footware and sports equipment, the service life performance of the LCP fiber
laces is
expected to be even better relative to the polyester fiber laces than the five-
times
ratio demonstrated in these tests.
In the preferred embodiments of this invention, the laces are comprised 100%
high-performance multifilament yarn that is melt spun from liquid crystal
polymer
(LCP), also known as aromatic polyester, such as that sold under the trademark
VECTRAN.
In other embodiments of the present invention, the laces comprise partially of
liquid crystal polymer (LCP) fibers and partially of other fibers. For
example, in such
alternate embodiments, the amount of LCP fibers in the laces by percentage of
total
fibers may be in an amount from a minimum of 30%, 40%, 50%, 60%, or 70% to a
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maximum of 50%, 60%, 70%, 80%, 90% or 99%, wherein a range may, for example,
be selected from any of the foregoing minimum values in combination with any
of the
foregoing maximum values, or any value lesser than, greater than or in
between, for
example, 30% to 99%, 60% to 99% or 80% to 99%.
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