U.S. patent application number 14/534717 was filed with the patent office on 2015-05-14 for abrasion resistant cords and ropes.
This patent application is currently assigned to POLTECO INC.. The applicant listed for this patent is Anagnostis E. Zachariades, Dimitris J. Zachariades, Nina Zachariades. Invention is credited to Anagnostis E. Zachariades, Dimitris J. Zachariades, Nina Zachariades.
Application Number | 20150128792 14/534717 |
Document ID | / |
Family ID | 53042536 |
Filed Date | 2015-05-14 |
United States Patent
Application |
20150128792 |
Kind Code |
A1 |
Zachariades; Nina ; et
al. |
May 14, 2015 |
ABRASION RESISTANT CORDS AND ROPES
Abstract
The abrasion resistance of organic fiber based ropes and cords
is increased by a outer woven cover of tapes of high molecular
weight and more preferably ultrahigh molecular weight
polyethylene
Inventors: |
Zachariades; Nina;
(Hillsborough, CA) ; Zachariades; Dimitris J.;
(Hillsborough, CA) ; Zachariades; Anagnostis E.;
(Hillsborough, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Zachariades; Nina
Zachariades; Dimitris J.
Zachariades; Anagnostis E. |
Hillsborough
Hillsborough
Hillsborough |
CA
CA
CA |
US
US
US |
|
|
Assignee: |
POLTECO INC.
Burlingame
CA
|
Family ID: |
53042536 |
Appl. No.: |
14/534717 |
Filed: |
November 6, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12579344 |
Oct 14, 2009 |
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14534717 |
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61107864 |
Oct 23, 2008 |
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61218875 |
Jun 19, 2009 |
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Current U.S.
Class: |
87/6 ; 87/7;
87/9 |
Current CPC
Class: |
D07B 1/04 20130101; D07B
2205/201 20130101; D07B 2205/201 20130101; D07B 2205/205 20130101;
A63B 29/028 20130101; B32B 2260/023 20130101; D07B 1/20 20130101;
B32B 2262/0253 20130101; D07B 2501/2092 20130101; D07B 2205/2046
20130101; D07B 2201/1096 20130101; D07B 1/147 20130101; D07B 1/025
20130101; D07B 2205/205 20130101; H01B 7/182 20130101; D07B 2801/12
20130101; D07B 2201/2092 20130101; D07B 2801/24 20130101; D07B
2801/22 20130101; D07B 2801/10 20130101; D07B 2801/10 20130101;
D07B 2801/22 20130101; D07B 2801/10 20130101; B32B 5/024 20130101;
D07B 2801/10 20130101; B32B 2262/0276 20130101; D07B 2501/2069
20130101; Y10T 428/2933 20150115; D07B 2201/209 20130101; D07B
2501/2061 20130101; B32B 2307/51 20130101; B32B 5/26 20130101; B32B
2307/54 20130101; D04C 1/12 20130101; D07B 2205/2014 20130101; B32B
2262/0261 20130101; D04C 1/02 20130101; D07B 2201/209 20130101;
D07B 2201/2003 20130101; D07B 2201/2003 20130101; B32B 2307/516
20130101; D07B 1/0673 20130101; B32B 27/02 20130101; B32B 2260/046
20130101; B32B 27/32 20130101; B32B 2307/56 20130101; D07B
2401/2075 20130101; D07B 2501/2038 20130101; D07B 2205/2014
20130101; D07B 2205/2046 20130101; Y10T 428/249922 20150401; Y10T
428/2967 20150115; Y10T 156/10 20150115 |
Class at
Publication: |
87/6 ; 87/9;
87/7 |
International
Class: |
D04C 1/12 20060101
D04C001/12; D07B 1/04 20060101 D07B001/04; D04C 1/02 20060101
D04C001/02; D07B 1/02 20060101 D07B001/02 |
Claims
1. A covering device having enhanced abrasion resistance
properties, said covering device comprising a braided construction
of at least one layer of a uniaxially oriented UHMWPE unitary tape
having a continuous and coherent structure.
2. A cord-like device having enhanced abrasion resistance
properties, said device comprising at least one interior cord
surrounded by an exterior covering, said exterior covering
comprising a braided construction of at least one layer of a
uniaxially oriented UHMWPE unitary tape having a continuous and
coherent structure.
3. A cord-like device having enhanced abrasion resistance
properties according to claim 2 wherein the core has a density
greater than water (1 gm/cc) and the cord-like device has a density
less than water (1 gm/cc).
4. A cord-like device having enhanced abrasion resistance
properties according to claim 2 wherein the interior cord comprises
a plurality of reinforcing structure selected from the group
consisting of fibers and tapes defining one or more strands, ropes,
cables, wires, coils or laces and the braid is woven tightly to
reduce the diameter of inner cord to a smaller diameter than the
initial diameter thereof.
5. A cord-like device having enhanced abrasion resistance
properties according to claim 2 wherein the braid substantially
compresses transversely the core of the cord-like device and
increases the abrasion resistance by a factor of at least about
1.4.
6. A cord-like device having enhanced abrasion resistance
properties according to claim 2 wherein the braid substantially
compresses transversely the core of the cord-like device and
increases the abrasion resistance by a factor of at least about
5.
7. A cord-like device having enhanced abrasion resistance
properties according to claim 5 wherein the weight fraction of the
braid is less than about 10% of the entire cord-like device.
8. (canceled)
9. (canceled)
10. A cord-like device having enhanced abrasion resistance
properties according to claim 2 wherein the interior cord comprises
bundles of fibers and the UHMWPE unitary tape that forms the braid
is impregnated with lubricating oil to reduce the internal abrasion
between the bundles of fibers in the interior cord.
11. A cord like device having enhanced abrasion resistance
properties, said device comprising a braided construction of
cord-like device members according to claim 2, wherein the UHMWPE
tape that forms the braid of each member of the cord like devices
of claim 2 is impregnated with lubricating oil to reduce the
surface abrasion between the crossing members of the braid
construction and the internal abrasion between the bundles of
fibers in the interior core of each member.
12. A cord-like device having enhanced abrasion resistance
properties according to claim 3 wherein the interior cord comprises
bundles of fibers and the UHMWPE unitary tape that forms the braid
is impregnated with lubricating oil to reduce the internal abrasion
between the bundles of fibers in the interior cord.
13. A cord-like device having enhanced abrasion resistance
properties according any of claim 2, wherein the UHMWPE has a
molecular weight greater than 3 millions.
14. A cord-like device having enhanced abrasion resistance
properties according to claim 2 wherein; a) the interior cord
comprises a reinforcing structure selected from the group
consisting parallel, braided, twisted fibers, woven fibers and
tapes, the fiber and tapes are high strength multifilament fibers
or tapes, b) said fibers or tapes being formed of at least one
polymer selected from the group consisting of ultra-high molecular
weight polyethylene, polyethylene, polypropylene, polyamide,
polyester, aromatic polyamide, and aromatic copolyester.
15. A cord-like device having enhanced abrasion resistance
properties according to claim 2 wherein the interior cord is an
electric or an electronic component.
16. A laminate structure comprised of one or more layers of a
thermoplastic sheet that is covered by a braided construction of at
least one layer of a uniaxially oriented UHMWPE unitary tape having
a continuous and coherent structure.
17. A laminate structure according to claim 16 wherein the UHMWPE
has a molecular weight greater than 3 million.
18. A laminate structure according to claim 16 wherein the
thermoplastic sheet is uniaxially oriented UHMWPE unitary tape
having a continuous and coherent structure.
19. A laminate structure according to claim 18 wherein the UHMWPE
has a molecular weight greater than 3 million.
20. A cord-like device according to claim 2 wherein the interior
cord comprises a plurality of uniaxially oriented UHMWPE unitary
tapes having a continuous and coherent structure.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a Continuation of and claims the
benefit of priority to the US Non-provisional patent application
having the same title and application Ser. No. 13/095,166, that was
filed on 27 Apr. 2011, which is incorporated herein by reference,
which is a Continuation-In-Part of and claims the benefit of
priority to the US Non-provisional patent application having the
same title and application Ser. No. 12/579,344 that was filed on
Oct. 14, 2009, which is incorporated herein by reference.
[0002] The present application claims the benefit of priority to
the US provisional patent application of the same title having
application Ser. No. 61/107,864 that was filed on Oct. 23, 2008,
which is incorporated herein by reference.
[0003] The present application also claims the benefit of priority
to the US provisional patent application of the same title having
application Ser. No. 61/218,875 that was filed on Jul. 19, 2009,
which is incorporated herein by reference.
BACKGROUND OF INVENTION
[0004] This invention relates to a covering device and a covering
material comprising high or ultra high molecular weight
polyethylene (UHMWPE). The invention is also directed to cord-like
devices such as ropes, cords, cables, conduits, strands of fibers
and tapes, etc. comprising the covering device or the covering
material mentioned above with superior abrasion resistance, reduced
weight and diameter.
[0005] New ropes are continually being developed to meet the needs
of specialized applications. Through rope engineering, it is
possible to design a rope with specific performance
characteristics. These characteristics are met by changing
materials and construction methods. Decisions as to what factors
are important must be made.
[0006] In a practical sense, advantages and disadvantages must be
traded off and compromises must be made to design the best rope for
a given application.
[0007] Some applications require: Strong low-elongation, light
weight and high abrasion resistance ropes for rescue;
Shock-absorbing ropes for the rock climber; Floating ropes for
marine uses and river rescue; Low-elongation, shock absorbing ropes
for caving and arborists; Soft responsive rappel ropes; Colored
rope for multi-rope management challenges; and Superior strength,
non stretching buoyant ropes for marine applications.
[0008] In general, ropes are constructed with multifilament fibers
in three strands twisted together or in various braided forms. The
various multifilament fibers used in rope manufacturing are
predominantly synthetic and made of polymers such as polyamides
(e.g. Nylon), polyesters (e.g. Dacron.RTM., polypropylene,
polyethylene (e.g. Dyneema.RTM. and Spectra.RTM.), aromatic
polyamides (e.g. Kevlar.RTM., Twaron.RTM.) and aromatic
co-polyesters (e.g. Vectran.RTM.).
[0009] Depending on the intended purpose of the rope, different
polymer fibers are used; polyamides for their stretching and shock
absorbing capability, polyesters for their UV and abrasion
resistance, polypropylene for its lightness and low cost,
polyethylene and aromatic polyamides for their high strength and
low extension.
[0010] However, these commonly used rope fibers also have certain
disadvantages that are associated with their particular chemical
structures. Polyamides and to a lesser extent polyesters absorb
water, polyamides and polypropylene are susceptible to UV
degradation, and aromatic polyamides are susceptible to fatigue
bending.
[0011] Also, whereas some of the rope fibers have higher abrasion
resistance than others, e.g. polyesters over polyamides, ultra high
molecular weight polyethylene over aromatic polyamides, all rope
fibers are made of bundles of multifilament fibers that is
structures that are produced to have a high degree of chain
orientation and extension and be strong in their axis direction. As
a result they are very weak in their lateral directions
perpendicular to their axis. For example, in high strength
polyethylene fibers, the molecular chains are held by weak van der
Waals forces in the lateral directions. Because of the very weak
lateral bonding between the filaments of multifilament fibers, when
ropes made of multifilament fibers are rubbed against other
materials encountered during their use, for example, rocks, stones,
cement, and salt crystals, their filaments shred and break down
into weaker microfilaments, a process that leads to the weakening
and destruction of the rope. The greater the degree of shredding
and break down of filaments and fibers the greater the destruction
of the rope.
[0012] In order to obtain the benefit of individual polymer
properties and manage the cost of the ropes particularly those
containing the costly high strength fibers of ultra high molecular
weight polyethylene and aromatic polymers, manufacturers combine
different polymer fibers for the construction of hybrid ropes, for
example a high strength ultra high molecular weight polyethylene or
aromatic polyamide as a core with a less expensive polyamide, a UV
resistant polyester or a light weight polypropylene as a braided
outside layer to protect the high strength core component.
[0013] This outside layer, or protective cover, is used to protect
the high strength performance core component for reasonable lengths
of time, and is used in proportions of 40-60% of the total weight
of the rope for example. It contributes a significant amount to the
weight of the rope for the role of protection as well as to the
overall volume of the rope, as the diameter is typically
substantially larger than that of the core component. This
protective layer can make the rope heavier, bulkier and more
difficult to handle.
[0014] Prior art shows various other efforts to improve the
abrasion resistance and hence the service life of the ropes. For
example, U.S. Pat. No. 4,534,163 (Issued to Schuerch on Aug. 13,
1985) shows the use of a urethane coating to impregnate a
polyethylene terephthalate fabric in the form of strips wound
around the core fibers and curing it to form a protective jacket
for abrasion. Polyurethanes are thermoplastic elastomers and may
exhibit better abrasion resistance over other rubbery materials,
however they fracture into debris between the fibers and can
contribute in the destruction of the fibers (Sloan, F., S. Bull,
and R. Longerich. "Design Modifications to Increase Fatigue Life of
Fiber Ropes." Oceans. 1. (2005): 829-835). Such failure mechanism
shows that polyurethanes provide a limited benefit as a coating and
a binder. Moreover, the addition of polyurethane to form a
protective jacket results in additional weight and larger volume,
i.e. the rope becomes heavier and larger in diameter. PCT Patent
Application no. WO 98/50621 (to Moraes Del Vecchio et al.,
published Nov. 12, 1998) reports (page 2, line 25-page 3, line 12)
that the application of polyurethane coatings has been tested and
found to have also other disadvantages, e.g. detachment,
concentration of stresses and strength reduction and manufacturing
problems.
[0015] WO 98/50621 shows another approach to improve the internal
abrasion of the core fibers by using underneath the outside braided
protective layer a polyethylene strip placed helically on the core
fibers in order to prevent seabed debris that pass through the
outside protective layer from reaching the core fibers and cause
their destruction by abrasion. Such an arrangement does not protect
the outside braiding layer of e.g. nylon or Dacron which rubs
against the seabed nor the additional layer of the polyethylene
strip which relies on the outside layer for its protection. In
other words, it is expected that the polyethylene under-layer to
have an inferior abrasion resistance to the outside protective
layer.
[0016] Therefore, there is a need in the industry for a covering
device or a covering material that responds to at least one
drawback of what is known in the field. More particularly, there is
a strong need for a new covering material or coating allowing the
manufacture of a new generation of ropes that can provide high
mechanical performance and other useful attributes such as floating
capabilities with enhanced abrasion resistance and hence longer
service lifetime in smaller diameters and lower weights than
currently used traditional ropes.
SUMMARY OF INVENTION
[0017] The present invention responds to the above need by
providing a covering device or a covering material having: enhanced
abrasion resistance properties required in reduced volume; and/or
providing floating capability.
[0018] More particularly, according to a first preferred aspect,
the invention relates to a covering device or a covering material
which comprises a braid or woven construction of ultra high
molecular weight polyethylene unitary filaments in the form of a
tape with continuous and coherent structure of oriented and
extended molecular chains connected together by taut molecular
entanglements. By tape, we mean an elongated member having a
substantially flat cross-section in which the width is much greater
than the thickness. While the members may have a high elastic
modulus and/or strength, the thickness is sufficiently thin that
the material can be bent for shaping and weaving into a covering
member around rope, cords and lines having a diameter that is
larger than the tape width. Preferred dimensions for such tapes are
provided elsewhere in the specification and in specific
examples.
[0019] According to another preferred aspect, the invention also
relates to a cord-like device having enhanced abrasion resistance
properties and/or reduced volume and weight and/or floating
capability. The cord-like device comprises an interior cord
surrounded by an exterior covering including a braid or woven
construction of high molecular weight polyethylene unitary
filaments in the form of a tape with continuous and coherent
structure.
[0020] According to another preferred aspect, the invention relates
to a cord comprising a plurality of parallel, braided, twisted or
woven strands, cables, ropes, wires, coils or laces made of a
plurality of parallel, braided, twisted or woven tapes. The tapes
comprise high molecular weight polyethylene unitary filaments with
continuous and coherent structure.
[0021] More preferably, the high molecular weight polyethylene
mentioned above has a molecular weight greater than 300,000, and
even more preferably greater than 3 millions.
[0022] According to another preferred aspect, the invention relates
to the use of a covering device as defined above, for covering a
cord.
[0023] According to another preferred aspect, the invention relates
to the use of a covering device as defined above, for covering a
conduit or a plurality of conduits.
[0024] According to another preferred aspect, the invention relates
to a process for the manufacturing of a cord-like device as defined
above. The process comprises the steps of:
[0025] a) providing an interior cord; and
[0026] b) applying an exterior covering around the interior cord to
form the cord-like device.
[0027] These and other features of the present invention will
become more apparent from the following description. The above and
other objects, effects, features, and advantages of the present
invention will become more apparent from the following description
of the embodiments thereof taken in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1A is a cross-section elevation of a first embodiment
taken transverse to the principle axis of the cord or rope.
[0029] FIG. 1B is a partial cut-away exterior elevation transverse
to the cord or rope on FIG. 1A
[0030] FIG. 2 is a cross-section elevation of another embodiment
taken transverse to the principle axis of the cord or rope.
[0031] FIG. 3 is a cross-section elevation of another embodiment
taken transverse to the principle axis of the cord or rope.
[0032] FIG. 4 is a cross-section elevation of another embodiment
taken transverse to the principle axis of the cord or rope.
[0033] FIG. 5 is a cross-section elevation of another embodiment
taken transverse to the principle axis of the cord or rope.
[0034] FIG. 6A is a cross-section elevation of another embodiment
taken transverse to the principle axis of the cord or rope, whereas
FIG. 6B is an enlarged view of the indicated portion of FIG. 6A
[0035] FIG. 7A-C are cross-sectional elevations of further
embodiment of a tape deployed in the cord or rope covering, which
in FIGS. 7A and B is taken transverse to the principle axis of the
tape, while in FIG. 7C is taking along the principle axis of the
tape.
[0036] FIG. 8 is a cross-sectional elevation of a further
embodiment of the invention in which a core of flat tape is covered
by the inventive braid.
DETAILED DESCRIPTION
[0037] Referring to FIGS. 1 through 8, wherein like reference
numerals refer to like components in the various views, there is
illustrated therein a new and improved cord, rope or cable,
generally denominated 100 herein.
[0038] As stated above, the present invention is first directed to
a covering device or a covering material having enhanced abrasion
resistance and their respective use for the making of cords or
cord-like devices covered by the covering device or covered by the
covering material.
[0039] The enhanced abrasion resistance is attained by the use of a
covering device or material comprising a braided or woven
construction of UHMWPE unitary filaments with continuous and
coherent structure of oriented and extended molecular chains
connected together by taut molecular entanglements unlike the
bundles of multifilament fibers known to be currently in use.
[0040] UHMWPE, a polyethylene with an ultra high molecular weight,
is known to have the highest abrasion resistance among most of the
important thermoplastic polymers and metals. Also, within the
UHMWPE family of polyethylene, it is known that the abrasion
resistance of UHMWPE increases with its molecular weight. Hence, an
UHMWPE that is used in the manufacturing of tapes for the exterior
covering of braid or woven layer may not necessarily be the same
with the UHMWPE that is gel or solution spun for making the high
strength core component. The term UHMWPE refers to the UHMWPE as
defined by the ASTM-D4020-81 and for the purposes of this
application, it includes polyethylenes with a molecular weight of
at least 300,000; or higher such as 3 millions or higher.
[0041] High strength UHMWPE fibrillar tapes having a continuous
coherent structure can be produced from melt crystallized,
pseudo-gel and compacted powder precursors as described in prior
art U.S. Pat. Nos. 4,587,163; 5,407,623 and 5,479,952, which are
incorporated herein by reference. A common characteristic of the
processes used in making the UHMWPE unitary is that they do not
involve fiber spinning procedures that lead to multifilament
fibers. The UHMWPE unitary tapes are made of oriented and extended
molecular chains connected by taut molecular entanglements that
make the fibrillar tapes coherent and with a continuous structure
unlike the multifilament fibers that shred.
[0042] Such unitary and fibrillar tapes made of oriented and
extended molecular chains connected by taut molecular entanglements
were used for constructing different braid forms and ropes.
[0043] In alternative, but currently less preferred embodiments the
tapes may be formed from HMWPE by melt extrusion in the form of a
tape, but more preferably some combination of first melt extrusion
and then either drawings or solid state extrusion through a die
having a tape shaped cross section to provide at least some
molecular orientation to the polyethylene molecules to increase the
strength and abrasion resistance of the tape. Such tapes preferably
have a fibrillar structure, but are essentially unitary in the
sense that the boundaries between the fibrils and micro-fibrils are
not weak and the tape itself does not shred and is abrasion
resistant.
[0044] It should also be appreciated that terms HMWPE and UHMWPE
can also embrace compositions initially formed form lower molecular
weight PE that is increased in molecular weight by cross-linking,
either by irradiation or chemical cross-linking agent, as for
example after extrusion but before or the fabrication to the final
dimensions of the tape.
[0045] Because of their shape, that is a tape as compared to a
bundle of fibers twisted into a substantially bulkier thread, the
resultant braid construction of the UHMWPE unitary tape was also
substantially thinner, which result in a cord-like device with a
reduced weight and diameter. The enhanced abrasion resistance of
the UHMWPE unitary tapes reduces the required amount of material
for the exterior coating and results in reduced volume and
weight.
[0046] Braided constructions of UHMWPE unitary tapes exhibit a
unique combination of features and properties because of the shape
and profile of the tapes, their structure, composition and their
properties. The UHMWPE unitary tapes are flat and thin, their width
and thickness can be modified for using them with different size
ropes and purposes. For example, UHMWPE tapes 3.4 mm wide and with
thickness in the range from 0.05 mm to 0.3 mm were used for the
fabrication of ropes with diameters in the range from under 10 mm
to 30 mm and over. For ropes with larger diameters such as 40-100
mm, the width of the tapes was increased to 7-12 mm, with even
larger widths being available. For smaller diameter cords, e.g.
less than 10 mm, UHMWPE tapes with widths of 1.7 mm were also used.
The width of the tapes could be adjusted by juxtaposing two tapes,
e.g. two 6 mm wide tapes acting as a 12 mm wide tape.
[0047] The thickness of the UHMWPE tapes could be adjusted also by
staggering the tapes on top of each other, thus building a braided
structure using unitary tape multi-layers, e.g. for a total
thickness of 0.6 mm comprised of two 0.3 mm or three 0.2 mm thick
tapes. Multilayer tapes are thin and provide layers of protection
against abrasion as well as warnings for certain amounts of wear.
When a top layer eventually thins out, there is a second tape layer
below it to provide additional abrasion resistance. Additional tape
layers can be included for even longer protection. Such multilayer
approach is not practical with bundles of multifilament fibers as
the outside protective layer becomes extraordinarily thick and
heavy.
[0048] Another benefit of the flat shape of the UHMWPE unitary
tapes is making in situ repairs. The coherent and continuous
surface of the tape is a more amenable surface than a multifilament
bundle of fibers for attaching adjacent tapes by thermo-mechanical
means. Multifilament fibers such as UHMWPE fiber, in general,
shrink and loose their mechanical properties when using such
means.
[0049] The profile of the UHMWPE unitary tapes can also be varied
from a smooth surface to a textured surface for increased traction
or holding for special purposes. Texture patterns can include
various shapes and forms, for example, dimples and indented lines
or fish scale patterns which allow holding ability in one or two
directions.
[0050] The UHMWPE unitary tapes, having a structure of oriented and
extended molecular chains that are held together by taut molecular
entanglements throughout their structure, exhibit high breaking
strengths, e.g. of about 500 MPa and a remarkable elastic response
that makes the braided constructions of the UHMWPE unitary tapes
strong and dimensionally stable under certain loads and thus able
to apply sustainable compressive loads onto the core fibers of a
rope. Thus, ropes with outside protective braids of UHMWPE unitary
tapes have reduced diameters not only because the UHMWPE tapes are
thin, occupy small volume and are not needed in large volume in
comparison to the bundles of multifilament fibers, but also because
they are strong and also capable of compressing and compacting the
core fibers through their elastic deformation (extension) during
the braiding process. For example, UHMWPE unitary tapes deform
elastically under loads as high as at least 20 MPa, but preferably
above 30 MPa, and when such load was to be applied to each of the
tape members of the braiding, the compression on the core was very
high. Doubling the breaking strength of a rope for the same size or
delivering the breaking strength of a rope at half the rope size by
using the features and properties of the UHMWPE unitary tapes is
possible and can be seen clearly when comparing the breaking loads
of a traditional braided rope comprising Dacron for the outside
braided protective layer and Dyneema as the core fiber and a rope
of the new generation comprising an outside protective braiding of
UHMWPE unitary tapes and a core of Dyneema fibers. For example, a
1/2'' diameter rope of double braided polyester with Dyneema core
has a breaking strength of 17,000 lbs whereas a rope of this
invention with the same diameter has a strength of 31,000 lbs, i.e.
a 45% increase. For a 3/8'' rope, the increase in strength is 53%
(see at the Table below)
TABLE-US-00001 Double Braid Polyester with Dyneema core Braid of
UHMWPE unitary tapes with Dyneema core Diameter Av. Tensile
Strength Diameter Av. Tensile Strength (in.) Core/Sheath (lbs)
(in.) Core/Sheath (lbs) 3/8 Dyneema Polyester 8,400 3/8
Dyneema/UHMWPE 18,000 1/2 Dyneema Polyester 17,000 1/2
Dyneema/UHMWPE 31,000
[0051] Such ropes appear and behave like cable products, as the
outside braiding and the core are "embodied" into one solid product
in which there is little relative motion between the different
components. An important corollary of such constructions is that
they minimize: a) both the internal friction through the restricted
motion of the rope components and the barrier properties of the
braiding construction of UHMWPE unitary tapes which prevent solid
debris of passing through the UHMWPE braiding of the unitary tapes
and b) the external abrasion though their outstanding abrasion
resistance.
[0052] In contrast, the bundles of multifilament fibers in braided
ropes are displaced relative to each other, because of their weak
lateral bonding and the free space between them, particularly in
rope locations of threads passing in cross directions or when the
rope is abraded against sharp edges. Such displacement causes
significant "fuzzing" (shredding) of the fibers even when
polyurethane is used to protect the fibers (Sloan, F., S. Bull, and
R. Longerich. "Design Modifications to Increase Fatigue Life of
Fiber Ropes." Oceans. 1. (2005): 829-835).
[0053] The present invention relates also to a cord-like device 100
having enhanced abrasion resistance properties as it comprises an
interior cord 110 surrounded by an exterior covering 120, as shown
in FIGS. 1A and 1B. The exterior covering comprises high molecular
weight polyethylene, and preferably UHMWPE.
[0054] As further shown in FIG. 1B, the exterior covering of the
cord-like device mentioned above is made of a braid or woven
construction of ultra high molecular weight polyethylene unitary
filaments in the form of a tape 125 with continuous and coherent
structure, having at least two sets of parallel tape members 121
and 122 interwoven to alternatively overlap each other, and in this
embodiment each set being disposed generally at about 90 degrees to
the other set and 45 degrees with respect to the principle or
longitudinal axis of the cord 100. It will be appreciated that the
angle of the wrapping and the number of layers can be varied from
this example without departing from the scope and spirit of the
invention as defined in the claims that follow.
[0055] The above mentioned cord-like device comprises an interior
cord 110. By the term "cord", it has to be understood any sort of
linear or longitudinal material such as, but not limited to,
strands, ropes, cables, wires, coils, laces or the like. The cord
is generally made of a plurality of fibers or tapes, preferably
made of a plurality of parallel, braided, twisted or woven fibers
or tapes.
[0056] The interior cord 110 may also comprise a plurality of
parallel, braided, twisted or woven strands, cables, ropes, wires,
coils or laces made of a plurality of parallel, braided, twisted or
woven fibers or tapes, generally illustrated as 109 in FIG. 2.
[0057] The fibers or tapes may be high strength polymer fibers or
tapes, or high strength fibers or tapes made of metal or metal
wires.
[0058] As for example in FIG. 3, the interior cord 110 has a first
set of fibers 111 surrounded by a second set of fibers 112 which is
then covered by the braided exterior cover of woven HMPE or UHMWPE
125 formed of unitary tapes 120.
[0059] The polymer fibers and tapes may be high strength
multifilament fibers or tapes comprising at least one polymer
selected from; but not limited to, the group consisting of
ultra-high molecular weight polyethylene, polyethylene,
polypropylene, polyamide, polyester, aromatic polyamide, and
aromatic co-polyester.
[0060] According to another aspect of the present invention, the
interior cord may also be an electric or an electronic component.
By electric component, it has to be understood any kind of electric
conductive material such as a conductive electric cable or wire
114. By electronic component, it has to be understood a television
cable, an optic-fiber cable, a coaxial cable, or the like. As for
example, as shown in FIG. 4 the electric cable or wire 114 is
surrounded by a plurality of parallel, braided, twisted or woven
strands, cables, ropes, wires, coils or laces made of a plurality
of parallel, braided, twisted or woven fibers or tapes 109 which is
which is then covered by the braided exterior cover 120 of woven
HMPE or UHMWPE tapes 120.
[0061] The interior cord may have a round or flat profile. An
example of flat profile may be the use of the covering device or
the coating material for covering or coating a HOMI cable or the
like (HDMI for "high definition multi media interface").
[0062] The interior cord may also be a cable wire, which can be
used in marine and other applications. As for example, FIG. 5
illustrates a cord 100 that is a cable having two electrical
conductors 114 and 114'.
[0063] It has to be understood that the cord-like device of the
invention may have a round or flat profile.
[0064] The covering device may be fully or partially intertwined
with the interior core, in order to enhance the cohesion between
the inside and outside parts of the cord-like device, enhancing
solidity and flexibility of the device, reducing its diameter and
enhancing security when it is used. The exterior covering device
comprised of UHMWPE unitary tapes will enhance the abrasion
resistance over multi-fibrillar fibers, and thus may be thinner and
hence lighter for a given abrasion resistance performance thus
allowing the construction of ropes of smaller diameter and reduced
weight.
[0065] According to another aspect, the invention also relates to a
cord comprising a plurality of parallel, braided, twisted or woven
strands, cables, ropes, wires, coils or laces made of a plurality
of parallel, braided, twisted or woven tapes. The tapes comprise
high molecular weight polyethylene unitary filaments with
continuous and coherent structure, providing to the cord higher
strength and resistance.
[0066] Preferably, the cord may further comprise fibers and/or
tapes made of at least one polymer selected from the group
consisting of ultra-high molecular weight polyethylene,
polyethylene, polypropylene, polyamide, polyester, aromatic
polyamide, and aromatic copolyester.
[0067] In other words, the cord of the invention may be made of any
sorts of strands or fibers known in the art of cords intermingled
with tapes of UHMWPE.
[0068] According to another embodiment of the invention a cord or
rope having a core comprising a plurality of bundles of
multifilament fibers has each bundle wrapped or intermingled with
UHMWPE unitary tapes impregnated with e.g. a mineral lubricating
oil to further reduce the internal abrasion between the bundles of
fibers in the core component.
[0069] A more preferred aspect of this embodiment are cord devices
600 with a large diameters, e.g. about 100 mm, which are
illustrated in FIGS. 6A and 6B comprising a braided construction of
ropes 109 with smaller diameter (e.g. about 9 mm), each such
smaller diameter rope made of bundles of multifilament high
strength fibers wrapped with a protective cover of UHMWPE braided
construction 601 of unitary tapes impregnated 602 with a mineral
lubricating oil to further reduce the internal abrasion between
crossing members and between the bundles of fibers in the core of
each small diameter rope. The amount of lubricating oil in the
UHMWPE tapes is in the range of 0.01-10.0% by weight.
[0070] Preferably, the UHMWPE unitary tapes deployed in the
embodiments of FIGS. 6 and 7 are high strength UHMWPE fibrillar
tapes having a continuous coherent structure, which optionally
retain a fraction of the oil medium used in the gel forming process
to provide the impregnated mineral lubricating oil.
[0071] In another aspect of the invention the UHMWPE unitary tapes
need not be flat, but can have a desired profile or texture at
least on the exterior, as shown in FIG. 7A-C. In FIG. 7A, the
texture extends out or bumps or knobs 921 from the top planar
surface 121a whereas in FIG. 7B the texture is provide by
depressions 922. In FIG. 7C the texture is provided by triangular
protrusions 923 that orient in a common direction so that the tape
can slip in a forward direction (arrow 901), but be grasped tighter
from movement in a backward direction (arrow 902). Although the
textures described above are on the upper tape surface 121a, which
is intended to be on the outside of the braided covering 120, the
textures can be on the upper surface and the lower surface
121b.
[0072] It should be appreciated the texture means may comprises any
manner or combinations of the deviations from a planar surface that
are illustrated in FIG. 7A-C.
[0073] To ensure a higher strength, the strands or fibers may be
preferably made of at least one polymer selected from the group
consisting of ultra-high molecular weight polyethylene,
polyethylene, polypropylene, polyamide, polyester, aromatic
polyamide, aromatic copolyester and combinations thereof.
[0074] The cord of the invention described above may be of course
covered by the covering device of the invention to ensure higher
abrasion resistance, to reduce the volume of the cord; and in some
occasions to provide a floating capability to the cord.
[0075] According to another aspect, the invention relates to a
process for the making of the cord like device defined above. The
process comprises the step of providing an interior core, which can
be the cord of the invention (including UHMWPE tapes) or any kind
of interior cords known in the art or defined above. The covering
device is then applied around the interior cord.
[0076] The covering device may have the form of a tape of UHMWPE.
The tape is applied around the interior cord as a bandage.
EXAMPLES
[0077] As an example of the present invention, a new line of
smaller diameter and lighter ropes with superior abrasion
resistance in comparison to existing ropes, has been made.
[0078] The higher abrasion resistance of the ropes is attained
through the incorporation in the rope of an outside braided layer
which is constructed with high strength UHMWPE unitary tapes of the
type described in this patent application.
[0079] A high strength UHMWPE tape of this application is unitary
in the form of a narrow strip or filament with a continuous
coherent structure in which the fibers are held together
intrinsically by molecular entanglements unlike the multifilament
fibers obtained by melt for example, solution or gel-spinning and
used in rope manufacturing in which the fibers are loose and
separate in their lateral directions. It has been found that such
unitary UHMWPE tapes are resistant to fibrillation, have a superior
abrasion and shredding resistance in comparison to the
multifilament fibers of polyamide, polyester, polyethylene,
polypropylene and aromatic polyamides and polyesters used in rope
manufacturing and can be braided into smaller diameter and lighter
constructions.
[0080] Other applications for such HMWPE unitary tapes, and more
particularly high strength UHMWPE unitary tape is to form
biocompatible and durable covering for a medical or bioimplantable
cord or device that deploys as the inner member natural tendons or
ligaments, as well as biopolymers and synthetic analogs thereof,
which may be desirable, for example in spinal applications.
Alternatively, such HMWPE unitary tapes, and more particularly high
strength UHMWPE unitary tape may be combined in the manner
disclosed herein, as well as with other materials, including
fibers, for deployment as tendons or ligaments in the above or
other applications. Such structures may in fact be shaped to match
the natural tissue that it replaces, and is not intended to be
limited to structures with constant round, flat or other
cross-sectional profiles.
[0081] One preferred application of the invention relates to
synthetic ligaments and in particular a synthetic ligament for
replacing the natural anterior cruciate ligament of the knee joint
which can be injured commonly during various activities such as
sporting and by sudden movements. The human anterior cruciate
ligament experiences loads ranging from over 100N to 700 N
(22.5-158 lbs) and tears under loads in the range of about 500 to
1700N (112.6-382 lbs), as is disclosed in U.S. Pat. No.
4,932,972.
[0082] A synthetic ligament device under the teachings of this
invention is a cord-like product made of an outside protective
braiding of UHMWPE unitary tapes and a core of braided or parallel
UHMWPE high strength fibers with the outside braiding applied
tightly on the core so that the outside braiding and the core are
embodied as one solid flexible cable. Such a cable-like product can
be flexed, bent or twisted by torsion and maintain the state of
deformation that it is subjected to. A synthetic anterior cruciate
ligament in the form described above allows for a more uniform and
better distribution of the tensorial, bending and torsional loads
that are generated during the joint movement on the high strength
fibers in the core which are held compacted together by the outside
braiding into a unified body in comparison to synthetic braided
ligaments of the prior art in which there is no mechanism for
compacting and holding the core fibers in such state during their
intended function in the body, as for example in the disclosures of
U.S. Pat. Nos. 4,731,084; 4,932,972; 5,456,722; 4,610,688 and
4,917,699, which are incorporated herein by reference. Synthetic
ligament samples based on the cord-like construction described
above having a diameter of about 6 mm (which is in the range of the
diameter of 4-6 mm of the human anterior cruciate ligamant) exhibit
an average tensile strength of 4200 lbs, a value that exceeds by
far the load conditions encountered in human use.
[0083] Braiding constructions of UHMWPE unitary tapes, having the
highest abrasion resistance of all other synthetic fibers used for
biomedical applications, are the most durable for surface abrasion
protection. In addition, because of the tight compaction of the
core fibers under the compressive action of the outside braiding,
the displacement between the outside braiding and the core fibers
is small to cause internal friction and wear of the high strength
fibers.
[0084] Synthetic ligaments with the braiding construction of this
invention have been prepared also having a flat profile, that is
comprised of a flat braided construction of UHMWPE unitary tapes
with a core of UHMWPE high strength fibers or tapes as described in
Examples 1 and 5. FIG. 8 illustrates in a cross-sectional elevation
transverse to the core of such a synthetic ligament 800 in which a
braided covering 120 of UHMWPE high strength tapes covers a core
801 of stacked parallel UHMWPE high strength tapes 125. The ends of
the ligaments can be spliced, sawed or fit to interlocking devices
for their fixation on the bones.
[0085] For example, a braid construction of UHMWPE tape 0.05 mm
thick and 3.00 mm wide had a total thickness of 1.00 mm. The
thickness of the braid construction could be modified with the
thickness of the UHMWPE tape that was used, the number of tapes
incorporated in the braid structure in twisted or untwisted form
and the braiding pattern.
[0086] Ropes made with fibers of ultra high molecular weight
polyethylene and aromatic polyamides and polyesters have superior
strength to weight performance as compared to metal wires. However,
their strength is reduced with abrasion wear, chaffing and soil and
dirt contamination and requires a sheath or cover with abrasion
resistance to protect the high strength core component or the rope
itself. Protection of such high performing fibers with an abrasion
resistant braided construction of UHMWPE unitary tapes of this
invention is beneficial against external and other environmental
factors.
[0087] This invention also relates to the use of high strength
UHMWPE unitary tapes in woven, braided and knitted structures, such
as:
[0088] a. A woven webbing product in which the structural element
is a unitary fibrillar tape of UHMWPE (as compared to a
multifilament UHMWPE fibrillar product).
[0089] b. A woven webbing product comprised of two outside layers
made of woven webbings of UHMWPE in which the structural element is
a unitary fibrillar tape or a multifilament fiber and one internal
multilayer component that is comprised of uniaxially oriented
UHMWPE fibrillar reinforcing tapes, the total layered structure
when bound together having an enhanced load bearing capacity that
depends on the load bearing performance of the two outside woven
layers and the number of the UHMWPE reinforcing tapes comprising
the internal multilayer component.
[0090] c. A woven webbing product comprised of two outside layers
of woven webbings of a polymer multifilament fiber such as a
polyamide, polyester, polypropylene and an internal multilayer
component that is comprised of UHMWPE fibrillar reinforcing tapes,
the total layered structure when bound together having an enhanced
load bearing capacity that depends on the load bearing performance
of the outside woven layers and the number of the number of the
UHMWPE reinforcing tapes comprising the inside multilayer
component.
[0091] d. A homogeneous braided or woven product, comprised of a
continuous outside sheath of an UHMWPE unitary tape or
multifilament fiber and a core multilayer comprised of a plurality
of UHMWPE fibrillar reinforcing tapes, in twisted or untwisted
form, having an enhanced load bearing capacity that depends on the
load bearing performance of the outside sheath layer and the number
of the UHMWPE reinforcing tapes that comprise the core.
[0092] e. A homogeneous braided or woven product comprised of a
continuous exterior sheath of a UHMWPE unitary tape or
multifilament fiber and a core multilayer comprised of a plurality
of high strength tapes, such as aromatic polymers such as
Vectran.RTM..
[0093] The concentration of the UHMWPE in the sheath as well as the
width of the UHMWPE tape can be varied to adjust the abrasion
resistance of the braided product to meet various requirements. A
sheath made of 100% UHMWPE tape has a superior abrasion resistance
compared to a sheath made with 30% UHMWPE and 70% polyester. A
braided product with a large diameter will have a better abrasion
resistance when the UHMWPE tape in the sheath is wider e.g. 2.5 mm
as compared to 1.0 mm.
[0094] The load bearing capacity of the tape reinforced woven and
braided structures, varies with the number of the tape elements
used. The UHMWPE tapes can be made to stand various breaking loads.
Assuming that a given UHMWPE tape breaks under a load of 100 Lbs,
then a woven or braided structure comprised of ten tapes for
reinforcement or load-bearing purposes can be made to break at 1000
lbs, excluding the load bearing capacity of the two woven external
layers or the braided sheath surrounding the UHMWPE reinforcing
tapes. Considering that each of the two external braided layers can
have a breaking load of 250 Lbs, the breaking performance of the
entire braided structure is 1500 Lbs. for a small thickness
increase of 0.5 mm.
[0095] Such woven structures have the following features: Enhanced
load bearing performance, High load bearing performance to weight
ratio, Superior abrasion resistance, Not water absorbing, Chemical
Resistance and UV Resistant.
[0096] The covering device of the invention may be used for: ropes,
cord, protective sheath for ropes, lines, belts, webbings,
protective siding, electronic components, and the like.
Example 1
[0097] Example 1. In one experiment a rope was made with a
protective braided layer of UHMWPE unitary tapes (0.05 mm thick and
3.4 mm) wide on a core of braided high strength UHMWPE fibers
having a diameter of 0.375 in. The weight of the protective UHMWPE
braided construction was 10% of the total rope weight. The outside
protective braiding of the UHMWPE unitary tapes was braided tightly
on the core of the rope and had the same diameter as the core
component. Samples of the rope were tested for their abrasion
resistance in comparison to the braided core of high strength
UHMWPE fibers for the same length of time, for example, 10 hours.
The abrasive material had a surface roughness of 68 micrometers.
The rope samples were held under tension against the abrasive
material that came in contact with the rope samples with a
periodicity of 60 cycles/minute.
[0098] The abrasion resistance of the samples was assessed by the
weight loss of the rope, the amount of dust trail of worn material
on the abrasive and the amount of shredding that was generated
during the test. The rope samples with the protective braiding of
the UHMWPE unitary tapes maintained their firmness throughout the
test and abraded very slowly and over a narrow contact area as was
manifested by a small and narrow dust trail of UHMWPE particles on
the abrasive material. The thickness of the UHMWPE unitary tapes of
the outside braiding that came in direct contact with the abrasive
material was somewhat reduced without the occurrence of any
shredding or any other onset of failure.
[0099] In comparison, the samples of the braided core of high
strength UHMWPE fibers without the outside protection changed
shape, became flatter against the abrasive material and were
abraded and failed by shredding and breaking the fibers of the
multifilament bundles over a broader contact area as was suggested
also by the wider dust trail on the abrasive material. Unlike other
high strength fibers such as nylon and polypropylene which shredded
and generated a lot of wear debris and exhibited a large weight
loss at the same time (see below), these unprotected samples
shredded but being more abrasion resistant they exhibited a smaller
weight loss. On the basis of weight loss the rope samples with the
protective braiding of the UHMWPE unitary tapes were 1.4.times.
more abrasion resistant over the unprotected braided core samples
of the high strength fibers discounting their shredding. It is
interesting that the two structures of chain oriented and extended
molecular chains of UHMWPE that is one unitary the other
multifilament fiber, show different modes of abrasion and wear out
to different extent under the same testing conditions.
Example 2
[0100] A braid construction with the unitary UHMWPE tape of this
invention (0.05 mm thick and 3.0 mm wide) was used as an outside
layer to a high strength core component of braided aromatic
polyamide (Kevlar.RTM.) fibers having a diameter of 0.5 in (12.7
mm). The UHMWPE tapes were braided snugly over the Kevlar.RTM. core
component. The resultant rope product had a diameter 0.33 in (8.38
mm), was firm and looked like a wire cable.
[0101] With the strength of the Kevlar.RTM. core unchanged, the
rope product featured the combined properties of the excellent
mechanical properties of Kevlar.RTM. in terms of breaking strength,
low extension and negligible creep with the superior abrasion wear
resistance of the exterior UHMWPE braided component that
Kevlar.RTM. lacks.
Example 3
[0102] A braid of unitary UHMWPE tapes of this invention (0.05 mm
thick and 3.0 mm wide) was used over a 0.5 in. (12.7 mm) double
braided Nylon rope construction. The weight fraction of the UHMWPE
exterior component was approximately 9% of the total rope weight.
The combination of the UHMWPE braided structure of this application
over the double braided nylon allowed the production of a floating
rope featuring the good shock absorbing characteristics and high
elongation of the nylon core with the superior abrasion resistance,
excellent UV resistance and non-water absorption behavior of
UHMWPE. The weight of the protective UHMWPE braided construction
was 9% of the total rope weight. The outside protective braiding of
the UHMWPE unitary tapes was braided tightly on the double braided
nylon rope, and had the same diameter as the double braided Nylon
rope before braiding it with the UHMWPE unitary tapes. Samples of
the rope were tested for their abrasion resistance in comparison to
the double braided Nylon rope of the same diameter and for the same
length of time (10 hours). The abrasive material had a surface
roughness of 68 micrometers. The rope samples were held under
tension against the abrasive material that came in contact with the
rope samples with a periodicity of 60 cycles/minute.
[0103] As in Example 1, the abrasion resistance of the samples was
assessed by the weight loss of the rope, the amount of dust trail
of worn material on the abrasive material and the amount of
shredding that was generated during the test. The Nylon rope
samples with the protective braiding of the UHMWPE unitary tapes
maintained their firmness throughout the test, and abraded very
slowly and over a narrow contact area as was manifested by a small
and narrow dust trail of UHMWPE particles on the abrasive material.
The thickness of the UHMWPE unitary tapes of the outside braiding
that came in direct contact with the abrasive material was somewhat
reduced without the occurrence of any shredding or other onset of
failure.
[0104] In comparison, the samples of the double braided Nylon rope
without the outside protection changed shape, became flatter as
they were squeezed under tension against the abrasive material.
They failed by shredding and breaking the fibers of the
multifilament bundles over a broader contact area as was suggested
also by the wider dust trail on the abrasive material and generated
a lot of wear debris. On the basis of weight loss the rope samples
with the protective braiding of the UHMWPE unitary tapes were
5.5.times. more abrasion resistant over the unprotected double
braided Nylon rope samples.
Example 4
[0105] A braid of unitary UHMWPE tapes (0.05 mm thick and 3.0 mm
wide) was used over a 0.5 in (12.7 mm) double braided multifilament
polypropylene construction. The combination of the UHMWPE braided
structure of this application over the double braided multifilament
polypropylene core allowed the production of non-water absorbing
and light floating rope also featuring superior abrasion resistance
and excellent UV resistance that polypropylene lacks on its
own.
[0106] The weight of the protective UHMWPE braided construction was
10% of the total rope weight. The outside protective braiding of
the UHMWPE unitary tapes was braided tightly on the double braided
polypropylene rope, and had the same diameter as the double braided
polypropylene rope before braiding it with the UHMWPE unitary
tapes. Samples of the rope were tested for their abrasion
resistance in comparison to the double braided polypropylene rope
of the same diameter using the same abrasion test conditions that
were used in Examples 1 and 3.
[0107] The polypropylene rope samples with the protective braiding
of the UHMWPE unitary tapes maintained their firmness throughout
the test, and were abraded very slowly and over a narrow contact
area as was manifested by a small and narrow dust trail of UHMWPE
particles on the abrasive material. The thickness of the UHMWPE
unitary tapes of the outside braiding that came in direct contact
with the abrasive material was somewhat reduced without any
shredding or other form of failure.
[0108] In comparison, the samples of the double braided
polypropylene rope without the outside protection changed shape,
became flatter as they were squeezed under tension against the
abrasive material. They failed by shredding and breaking the fibers
of the multifilament bundles over a broader contact area as was
suggested also by the wider dust trail on the abrasive material and
generated a lot of wear debris. On the basis of weight loss the
rope samples with the protective braiding of the UHMWPE unitary
tapes were 11.5.times. more abrasion resistant over the unprotected
double braided Nylon rope samples.
[0109] Accelerated abrasion testing was performed on various
constructions with and without the UHMWPE tape cover of this
invention under load against rotated abrasive surfaces with
roughness exceeding 60 micrometers. Ropes with an outside braid
construction of unitary UHMWPE tapes of this invention outperformed
all ropes in which the outside braid was constructed of a
traditional fiber such as nylon, polypropylene, and even
Dyneema.RTM.. The weight loss of a rope of this invention was about
6.5 times less in comparison to a rope with an outside braid of
nylon, about 8.4 times less in comparison to a rope with an outside
braid of polypropylene and about 1.5 times less in comparison to a
Dyneema.RTM. construction over the same length of time, 10 hours
testing time for example. Noteably, the UHMWPE tapes did not fray
during this test, while all the other constructions did.
Accordingly, it is expected the actual useful life of the inventive
product will greatly exceed comparable uncovered ropes by a much
greater factor than the above weight loss ratios. The accelerated
tests with and without the protecting braids of the UHMWPE unitary
tapes show that ropes with such protective braidings outperform all
the traditional multifilament fibers used in rope manufacturing.
Multifilament fibers begin to shred fast with abrasion whereas the
UHMWPE unitary tapes show no signs of failure even after 10 hours
of testing under the same abrasion conditions.
Example 5
[0110] Hollow braid constructions of unitary UHMWPE tapes were
prepared in different diameters, e.g. 0.375, 0.5 and 1.0 in (9.52;
12.7 and 25.4 mm), for covering three strand ropes and other linear
products e.g. cables, cords, strands of fibers, pluralities of
tapes, and wires and protecting them from wear.
[0111] For example, a flexible tubular braid or woven construction
of unitary UHMWPE tapes with a diameter of approximately 1 in. was
used as the outside layer to make flat "braid-on-core"
constructions in which the core was comprised of a number of high
strength UHMWPE tapes assembled into a flat multilayer structures
from a few to a large number of layers instead of the traditional
strands or threads of high strength fibers with round cross
section. Using UHMWPE tape that was less than 0.002 in. (0.05 mm)
thick and had a breaking strength of for example 100 lbs, a very
thin and light flat braid-on-core construction was made in which
the core made of a multilayer structure of for example 20 layers,
had a breaking load performance of 2000 lbs. The high strength core
component could be made with different pluralities of high strength
UHMWPE tapes, 5, 10, 20 and higher number of tape layers and
incorporates tapes of different polymers for different
performances. Flat "braid-on-core" structures can be useful in the
manufacturing of thin and strong line products such as slings.
[0112] The development of strong, light weight and small diameter
ergonomic ropes combining the superior abrasion resistance
characteristics of the braided constructions with the unitary
UHMWPE tapes of this invention with core components of high
strength fibers can be valuable for various uses and applications
where external and environmental factors degrade the strength of
the rope, and where space and weight limitations are issues of
consideration.
[0113] Webbings are used commonly for various load-bearing
applications such as seat belts, outdoor gear and equipment, belts
and tightening straps and in lifting operations such as for pipes,
lumber and boats. The load-bearing performance of the webbing
depends on the strength of the multifilament fiber and the webbing
pattern. Traditionally webbings are made by weaving multifilament
fibers of polyamides, polyesters, polypropylene or in combination
with fibers of high strength such as aromatic polyamides (such as
Kevlar.RTM.) for improving the load-bearing performance of the
webbing.
Example 6
Laminates
[0114] Laminate structures are a form of composite structures
combining certain mechanical performance. For enhanced mechanical
performance, the laminates are reinforced with traditional and high
performance multifilament fibers, which are laid in various
patterns and configurations between the laminating layers.
[0115] The laminate structures of the present invention relates to
the use of unitary fibrillar reinforcing tapes of UHMWPE for the
reinforcement of composite structures. More particularly, the
laminate structures comprised of one or more layers of
thermoplastic non-woven or woven sheet and one or more layers of
unitary uniaxially oriented UHMWPE fibrillar reinforcing tapes in
woven and nonwoven form.
[0116] A feature of the unitary UHMWPE reinforcing tapes is that
the fibers in their fibrillar structure are bound intrinsically
together without voids between the fibers and without the need for
binding media. This allows the construction of less bulky and more
flexible laminate structures. Said reinforcement tapes are less
susceptible to fraying than multifilament reinforcing fibers.
[0117] Having a larger surface area, the said reinforcing tapes
promote better adhesion in comparison to multifilament fibers.
UHMWPE reinforcing tapes have widths from 0.1 mm to over 25 mm and
greater. In addition, they distribute working loads more uniformly
and prevent more effectively the tearing of the non-woven or woven
sheet that they are reinforced.
[0118] One example of such laminate consists of two Mylar.RTM.
sheets with said reinforcing tapes in between, the layers being
bound with adhesive. Another example involves a woven sheet, such
as that of Nylon or polyester, with said reinforcing tapes attached
to or sandwiched in between.
[0119] Reinforcing tapes may be used alone or in combination with
other reinforcing monofilament or multifilament fibers such as
Kevlar.RTM.. They can also be used with thermosetting types of
polymers for more rigid composite structures. Applications of the
materials and constructions include: sails, fabric reinforcement,
technical apparel outdoor gear, cargo siding and covering,
coverings, reinforced plastic paneling among others.
[0120] Although the present invention has been explained
hereinabove by way of preferred embodiments thereof, it should be
pointed out that any modifications to this preferred embodiment
within the scope of the appended claims is not deemed to alter or
change the nature and scope of the present invention. For example,
the cover can be applied or braided under different degrees of
tension to fit loosely or tightly and thereby give different
degrees of flexibility and rigidity to the cord.
[0121] While the invention has been described in connection with a
preferred embodiment, it is not intended to limit the scope of the
invention to the particular form set forth, but on the contrary, it
is intended to cover such alternatives, modifications, and
equivalents as may be within the spirit and scope of the invention
as defined by the appended claims.
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