Note: Descriptions are shown in the official language in which they were submitted.
132~193
CUT RESISTANT YARN, FABRIC AND GLOVES
BACKGROUND OF THE INVENTION
The first embodiment of this invention
relates to a cut resistant jacket for ropes, webbing,
straps, inflatables and the like, more particularly a
cut resistant article comprising a cut resistant jacket
surrounding a less cut resistant member where the
jacket comprises a fabric of a yarn and the yarn
consists essentially of a high strength, longitudinal
strand having a tensile strength of at least 1 GPa and
the strand is wrapped with a fiber.
The second embodiment of this invention
- relates to cut resistant yarns and their use in
protective garments. There are many applications for
such protective garments. Meat processing employees
exposed to sharp knives require such garments. Metal
and glass handlers who must be protected from sharp
edges during the handling of materials may use such
protective garments. Medical personnel who are exposed
to scalpels and other sharp instruments may obtain
protection through the use of such garments.
It is known to make cut resistant fabric for
gloves used for safety in the meat cutting industry as
described, for example, in U.S. Patent 4,470,251, U.S.
Patent 4,384,449 and U.S. Patent 4,004,295. It is also
known to make a composite line containing two different
filamentary materials in the form of a core and a
jacket of different tensile strengths and elongations
as in U.S. Patent 4,321,854. It is also known to make
composite strand, cables, yarns, ropes, textiles,
filaments and the like in other prior U.S. patents not
cited herein.
In the prior art, U.S. Pat. No. 3,883,898
suggests that an aramid fiber, such as KEVLAR*, be used
*Trademark
-2- 1325~03
in cut resistant gloves that are worn by meat processors.
U.S. Patent No. 3,953,893 teaches using an aramid fiber in
cut resistant aprons.
U. S. Patent No. 4,004,295 suggests the use of a
glove composed of yarn of metal wire and a nonmettalic
fiber such as an aramid fiber as protection from knife
cuts, especially in meat processing plants. U. S. Patent
No. 4,384,449 and 4,470,251 also suggest the use of metal
wire in combination with aramid fibers.
U. S. Patent No. 4,651,514 suggest the use of a
yarn composed of a monofilament nylon core that is wrapped
with at least one strand of aramid fiber and a strand of
nylon fiber. The stated advantage of this yarn over that
15 suggested in, for example, U. S. Patent No. 4,004,295 is
that this yarn is electrically nonconductive.
By ultrahigh molecular weight is meant 300,000
to 7,000,000. Normal molecular weight is then below
300,000.
By fiber herein is meant any thread, filament
or the like, alone or in groups of multifilaments,
continuous running lengths or short lengths such as staple.
By yarn herein is meant any continuous running
length of fibers, which may be wrapped with similar or
dissimilar fiber, suitable for further processing into
fabric by braiding, weaving, fusion bonding, tufting,
knitting or the like, having a denier less than lO~OOOo
By strand herein is meant either a running
length of multifilament end or a monofilament end of
continuous fiber or spun staple fibers, preferably
untwisted, having a denier less than 2,000, or, regarding
the first embodiment only, metal of diameter less than
0.01 inches.
For many applications, cut resistant garments
made using the prior art have undesirable disadvantages or
limitations. Garments made using only high strength
polyethylene or other fibers offer improved levels of cut
protection. Elowever, very sharp edges, such as newly
sharpened knives, can cut even very cut resistant fibers
132~103
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with only moderate cutting forces. The addition of metal
wire to a yarn containing one of the above high strength
fibers can improve yarn cut resistance. Even very sharp
edges can have difficulty cutting through a yarn made of
aramid and metal fiber. However, such yarns are much
less flexible due to the stiffness of the metal. If a
garment is too stiff the wearer may become fatigued by
using it, or in an extreme case may remove the garment and
lose the intended protection. Repeated use and flexing of
the garment may cause the relatively stiff metal wire to
break. In this case it is likely tllat the broken wire
ends will protrude from the yarn. These sharp wires
protruding from the garment may scratch the wearer or any
objects being handled.
The use of metal wire in a cut resistant yarn
makes the yarn electrically conductive. This means that a
garment made with such a yarn cannot be used in contact
with high-voltage electrical equipment. The use of a
nylon monofilament, instead of metal wire, in a cut
resistant yarn removes the problem of electrical
conductivity. However, the use of nylon monofilament
results in a less cut resistant yarn. The nylon is much
more easily cut by very sharp edges than is metal wire.
Therefore, the yarn as a whole is more easily cut.
The present invention overcomes many of the
limitations of cut resistant yarns made using the prior
art. The present invention can have a cut resistance
equal to or beter than that obtained by using yarn
containing metal wire, however, it does not have the
stiffness or electrical conductivity associated with a
yarn containing metal wire.
SUM~ARY OF THE INVENTION
The first embodiment of this invention is a cut
resistant article comprising a cut resistant jacket
surrounding a less cut resistant member. The jacket
comprises a fabric of yarn~ The yarn consists essentially
of a high strength, longitudinal strand having a tensile
strength of at least 1 GPa. More than one strand can be
- 132~103
used. This strand (or strands) is wrapped with a fiber.
The fiber may be the same or different than the
longitudinal yarn.
It is preferred that the fiber wrapped around
the strand also have a tensile strength of at least 1 GPa.
The less cut resistant member can be selected
from the group consisting of rope, webbing, strap, hose
and inflatable structures.
The core strand fiber of the rope, webbing,
strap or inflatable structures could be fiber of nylon,
polyester, polypropylene, polyethylene, aramid, ultrahigh
molecular weight high strength polyethylene or any other
known fiber for the use.
The inflatable structure would be a less cut
resistant layer having the fabric of this invention as a
jacket or outer layer. The strand used for the fiber in
the jacket may be selected from the group consisting of an
aramid, ultrahigh molecular weight polyolefin, carbon,
metal, fiber glass and combinations thereof. The fiber
used to wrap the longitudinal strand (or strands) can be
selected from the group consisting of an aramid fiber,
ultrahigh molecular weight polyolefin fiber, carbon fiber,
metal fiber, polyamide fiber, polyester fiber, normal
molecular weight polyolefin fiber, fiber glass,
polyacrylic fiber and combinations thereof. When the
fiber wrapping is a high strength fiber having strength
over 1 GPa, the preferred fiber wrapping is selected from
the group consisting of aramid fiber, ultra high molecular
weight polyolefin fiber, carbon fiber, metal fiber, fiber
glass and combinations thereof.
The polyolefin fiber of this invention can be
ultrahigh molecular weight polyethylene or polypropylene,
preferably polyethylene, commercial examples are Spectra~
900 and Spectra~ 1000.
The fiber wrapping can also be a blend of a
lower strength fiber with the high strength fiber. Such
lower strength fiber can be selected from the group
consisting of polyamide, polyester, fiber glass,
1 3 2 ~ 3
polyacrylic fiber and combinations thereof.
The article of this invention can also have more
than one jacket surrounding the less cut resistant member.
In another example of the first embodiment, the
article of this invention has a material present in the
interstices of the fabric of the jacket to bond the yarn
of the fabric to adjacent yarn of the fabric thereby
increasing penetration resistance of the jacket. The
material used in the interstices can be any elastomer,
preferably a thermoplastic rubber and more preferably a
material selected from the group consisting of
polyurethane, polyethylene and polyvinyl chloride.
In a second embodiment, the present invention is
a highly cut resistant composite yarn. The yarn is
comprised of at least two fibrous materials. All
materials in the yarn are nonmetallic. At least one of
the materials is required to be highly flexible and
inherently cut resistant. At least one of the materials
is required to have a high level of hardness. An example
of such a yarn results from the combination of glass
fiber, which is a hard fibrous material, and high
strength, extended-chain polyethlyene fiber, which is a
flexible and inherently cut resistant fibrous material.
Garments, such as gloves, made from yarn of the
present invention are highly cut resistant. They are also
very flexible and nonconductive.
The present invention differs from the prior
art in that a nonmetallic, hard fibrous material is used
as a component of the yarn. The only hard fibrous
material suggested in the prior art is metal wire. Other
materials suggested by the prior art, such as nylon, are
not considred hard materials.
It is somewhat surprising that brittle, hard
materials, such as glass fibers, can add such a
significant level of cut resistance to the composite yarns
of the present invention. It would normally be assumed
that such brittle materials would easily break and provide
little protection when the yarn is impacted with a cutting
132~1~3
-- 6
edge. However, it has been found that when very small
diameter glass is used in the core of the yarn, and
optionally is protected by an outer wrapping of
flexible fiber or elastomeric coating, the composite
yarn is very resistant to breakage during cutting.
More specifically, the second embodiment of
this invention is a cut resistant yarn comprising at
least two nonmetallic fibers with at least one being
flexible and inherently cut resistant and at least
another having a high level of hardness. The level of
hardness is preferred to be above about 3 on the Mohs
hardness scale. It is preferred that the cut resistant
fiber would be resistant to being cut for at least 10
cycles on the cutting apparatus described in U.S.
Patent No. 4,864,852, issued September 12, 1989, with
cutting weight of 135 gr., mandrel speed of 50 rpm,
steel mandrel diameter of 19 mm, blade drop height of
9mm, using a single-edge industrial razor blade for
cutting, said fiber being tested as a knitted fabric
comprised of 2400 denier fiber, with less than 2 turns
per inch of twist, and being knitted on a 10 gauge
knitting machine to a fabric of 11 oz. per sq. yd. The
preferred cut resistant fiber is selected from the
group consisting of high strength polyethylene, high
strength polypropylene, high strength polyvinyl
alcohol, aramids, high strength liquid crystal
polyesters and mixtures thereof. The preferred fiber
having the high level of hardness is selected from the
group consisting of glass, ceramic, carbon and mixtures
thereof. It is preferred that the fiber having a high
level of hardness have a diameter of at most about 12
microns, most preferably the diameter is between about
2 and about 10 microns. Another preferred fiber having
a high level of hardness can be a multiple component
fiber of any diameter or thickness which can have a
softer core material and an outer coating of the hard
material, such as glass, ceramic or carbon. Likewise,
this hard fiber could be a composite fiber of any
thickness wherein the matrix is a softer material
impregnated with the hard material such as
'~
132~103
--7--
carbon, glass or ceramic. Mixtures of any of the hard
fibers mentioned above would also be useful. The fiber
having a high level of hardness can be coated with an
elastomeric coating. The second embodiment is also a
fabric made from the yarn of the combined fibers described
above, and garments such as gloves made of such fabric.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Yarns for Jacket Fabric (First Embodiment)
A yarn to be used to make the protective jacket
fabric of the first embodiment of this invention is made
by wrapping one longitudinal strand of stainless steel
wire having a diameter of 0.11 mm and one parallel strand
of an ultrahigh molecular weight polyethylene fiber having
a tensile strength of 3 GPa modulus of 171 GPa, elongation
of 2.7 percent, denier of 650 and 120 filaments per strand
or end. This yarn is commercially available as Spectra
1000 fiber from Allied Corporation. The wrapping fiber is
a polyester of 500 denier, 70 filaments per end, having a
tensile strength of 1.00 GPa, modulus of 13.2 GPa,
elongation of 14 percent. For yarn A two layered wraps of
the above polyester fiber are used to wrap the parallel
strands of wire and high strength polyethylene.
For yarn B one layer of the ultrahigh molecular
weight polyethylene fiber described above is used as the
innermost layer wrapped around the strands, the outer
layer being the polyester fiber.
Alternatively, an aramid such as Kevlar could be
used to replace the ultrahigh molecular weight
polyethylene, either as the strand or as the fiber for
wrapping.
Comparative Yarn C - a polyester of 3600 denier,
1 GPa tensile strength, 13.2 GPa modulus and 14 percent
elongation, without wrapping.
This wrapped yarn (A or B) or comparative yarn C
can then be braided, knitted, woven or otherwise made into
fabric used as the jacket of this invention.
This jacket can then be used to surround ropes,
webbing, straps, inflatable structure, and the like. The
,, ' ~ --
132~1~3
--8--
jacket can be made from one or more ends of yarn per
carrier in the braider apparatus. Either full or partial
coverage of the core of braided or parallel strands can be
achieved. The yarn for the fabric used for the jacket in
this invention can also be wrapped in a conventional
manner such as simply wrapping the strand of high strength
fiber or by core spinning or by Tazalanizing or any other
method to put a wrap of yarn around the strand or strands.
Cut Resistant Yarn (Second Embodiment)
The yarn of the second embodiment of the present
invention is comprised of at least two fibrous materials,
with at least one being flexible and cut resistanct and at
least another which must have a high level of hardness.
The desirability of using this particular combination of
materials has been made apparent through careful
observation of the cutting action of sharp edges against
various fibrous materials.
It is known that certain fibrous materials have
an inherently high level of cut resistance. For example,
aramid fibers, such as "Kevlar", are difficult to cut
compared to most other synthetic fibers. As an example,
more force is required to cut through an aramid fiber than
through an equivalent amount of polvester fiber, assuming
the cutting edge sharpness is the same in both cases.
It has been observed that extended-chain
polyethylene (ECPE) fibers, such as "Spectra", are also
inherently cut resistant. ECPE fibers, in addition to
being highly cut resistant, are very abrasion resistant
and flexible, providing a superior cut-resistant yarn.
The present invention requires that at least one
of the fibrous materials in the yarn be a flexible,
inherently cut resistant material such as, but not limited
to, an aramid fiber or ECPE fiber.
While materials such as aramid fibers and ECPE
fibers are cut resistant, even they can be cut through
with re'atively moderate force if an extremely sharp edge
is used during cutting and if the edge is pulled across
the material while the cuttiny force is being applied. In
1323l~3
the course of deve:oping the present invention it was
discovered that adding a hard fibrous material to the
flexible, inherently cut resistant material dramatically
increased the cut resistance of the yarn. It was
discovered that the hard material dulled the cutting edge
during the cutting process, and as a result made it more
difficult for the edge to cut through.
The assumption that the hard material was
responsible for dulling the sharp edge and making it more
difficult to cut the yarn was verified by the following
simple test. A sample of knitted ECPE fabric was cut with
a previously unused scalpel blade. Enough force was
applied, by hand, as the scalpel was pulled across the
fabric to cut through the fabric. Next, a similar unused
scalpel blade was brought in contact with a 25 denier
glass fiber. The cutting edge of the scalpel was pulled
over the glass fiber under moderate hand pressure, the
pressure being not so great as to break the glass fiber,
such that the entire cutting edge made contact with the
glass fiber. This scalpel was then used to cut the ECPE
fabric mentioned before. It was found that the force
required to cut through the fabric was greatly increased
for this case. It was obvious that pulling the scalpel
edge over the glass fiber had reduced the sharpness of the
edge. It was found that if the scalpel edge was
repeatedly made to contact the glass fiber, the edge could
be dulled to the extent that the ECPE fabric could not be
cut through at any level of hand pressure. In contrast,
if a previously unused scalpel was used to repeatedly cut
the ECPE fabric, the force required to cut did not
increase with the number of cuts. It was obvious that the
ECPE was not noticeably dulling the scalpel edge.
For the purposes of this invention, any
nonmetallic, hard fibrous material may be used. Glass
fibers and ceramic fibers are common examples o~ such
materials. For the purposes of this invention, "hard"
material is any material that has a hardness level such
that it is capable of significantly reducing the sharpness
-lO- 1~2~1~3
of a cutting edge.
The form that the hard fibrous material takes
can be quite varied. The hard fibrous material can be of
uniform composition and continuous in length, such as a
continuous filament glass fiber. It may be of
noncontinuous length, such as chopped glass fiber. It may
be nonuniform in composition. For example, the fibrous
material may be composed of an organic fiber coated with
layer of ceramic material. Another example would be that
of an organic fiber which is impregnated with ceramic
particles or fibrils. The foregoing examples are for
illustration only in that numerous modifications can
readily be imagined by one skilled in the art.
An assumption that might be made, even by one
skilled in the art, is that hard fibrous materials used as
part of this invention would be very brittle and,
therefore, of limited use in garments. In practice, the
brittleness of the hard materials used is not a major
concern. The glass or ceramic fibers that would normally
be used in this invention are extremely small in diameter.
If larger diameter is required, a coated or impregnated
fiber, described above, can be used. As a result, these
hard materials are still very flexible and can be bent
around a very small radius without breaking. It is
preferred that the hard fibrous material be placed in the
core of the composite yarn. In this manner, the hard
material is exposed to the least stress during bending of
the yarn. In addition, by placing the hard material in
the core of the yarn, the outer layers of flexible,
inherently cut resistant material help protect the more
brittle core material.
In many cases, it will be preferred that the
hard fibrous material be coated with a continuous layer of
elastic material. This coating has several important
functions. If the hard material is a multifilament fiber,
the coating holds the fiber bundle together and helps
protect it from stresses that develop during handling of
this fiber before it is placed in the composite yarn. The
- 11 132~1~3
coating may provide a physical barrier to provide
chemical protection for the hard material.
Additionally, if the hard material is broken during
use, the coating will trap the material so that it will
not leave the yarn structure.
A cut testing apparatus useful to measure
the cut resistant of fibers and yarns of this invention
is described in U.S. Patent No. 4,864,852, issued
September 12, 1989.
Example 1 - Tests on Ropes (First Embodiment)
Three different stranded ropes, jacketed
with a cut protective fabric, were tested for cut
resistance. Three conventional stranded 1/4-inch (0.6
cm) ropes were made and a special braided yarn fabric
was used to surround the rope core as a jacket. The
jacket can be formed either separately and placed on
the core of rope or formed around the core during one
of the manufacturing steps.
Comparative Sample 1 was a Kevlar stranded
rope jacketed with fabric braided from comparative yarn
C. Comparative Sample 2 was an ultrahigh molecular
weight high strength polyethylene (Spectra~ 900) fiber
stranded rope jacketed with fabric braided from
comparative yarn C. Example of this invention Sample 3
was the above-described ultrahigh molecular weight
polyethylene (Spectra~) fiber strand rope, surrounded
with a jacket braided from Yarn A. Spectra 900 fiber
has a denier of 1200, 118 filaments per strand
typically, tensile strength of 2.6 GPa, modulus of 120
GPa and elongation of 3.5 percent.
The three jacketed ropes were tested by a
guillotine test. In the guillotine test, the rope was
held in a fixture so its movement was restricted.
Clamps prevented it from moving along its axis and the
rope was inside two pieces of pipe to prevent it from
deflecting during cutting. The two pieces of pipe were
separated very slightly where the blade made the cut.
The maximum force needed to completely sever the rope
was measured.
In the second test, the cut-damage test, the
rope was laid on a wooden surface without further
1325~03
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restraint. A blade was then forced into the rope at 250
pounds (113.6 kg) of force. The damaged ropes were tested
for retained strength. In both tests a new Stanley blade
no. 1992 was used for each sample tested. The results of
the tests are given below.
Guillotine Test Results
Pounds of Force to Cut
Comparative Comparative
10 TestSample 1 Sample 2 Sample 3
(kg) (kg) (kg)
1 132 (60 ) 227 (103) 684 (311)
2 139 (61.8) 335 (152) 638 (290)
3 144 (65.5) 286 (130) 616 (280)
15 Avg. 138 (62.7) 282 (128) 646 (294)
Cut Damage Test Results, Percent Strength Retained
73 85 97
Observation of the cut damage test ("abused")
ropes showed that the Sample 1 rope was cleanly cut part
way through. The Sample 2 rope jacket was also partly cut
through but the filaments were not as cleanly cut. Sample
3 rope showed only a depression where the blade was
pressed. There was no evidence of even the jacket having
been cut. Because of this only Sample 3 rope was tested
at 500 pounds force in the cut damage test. It retained
92 percent strength and sustained no jacket cutting.
Example 2 - Abrasion Resistance (First Embodiment)
Comparative Sample 2 and Sample 3 (this
invention) were tested for abrasion resistance of the
jacket by the test described below. Sample 3 was a 1/4-inch
(0.6 cm) stranded rope jacketed with a braided fabric of
yarn A.
In the test each sample rope was bent in a 90
degree angle over a 10-inch (25.3 cm) diameter abrasive
wheel. The ropes were loaded with 180 pounds (81.8 kg)
and reciprocated through a 3-inch (7.6 cm) stroke as the
abrasive wheel rotated at 3 rpm. The test ended when the
jacket wore through. The number of strokes (cycles) for
each was 8 for Comparative Sample 2 and 80 for Sample 3.
-13- 132~1~3
Example 3 - Braided Rope (First Embodiment)
Four 1/4-inch (0.6 cm) braided ropes were tested
with various jackets. Comparative Sample 4 rope was
braided from the high strength, ultrahigh molecular weight
polyethylene yarn described above and the jacket was
braided from a polyester yarn of 1000 denier, 192
filaments per end, 1.05 GPa tensile strength, 15.9 GPa
modulus, and 15 percent elongation.
Sample 5 rope was braided from Kevlar yarn of
1875 denier, 2.53 GPa tensile strength, 60.4 GPa modulus
and 3.5 percent elongation. The jacket was as in Sample 3.
Sample 6 rope was also braided, from the high
strength ultrahigh molecular weight polyethylene yarn
described above, under low tension to give a "soft" rope.
The jacket used was as in Sample 3.
Sample 7 rope was identical to Sample 6 except
more tension was applied during braiding of the rope to
create a "hard" rope.
A fixed load was applied to the rope as in
Example 1. When the ropes were taut under the knife,
there was little difference in cut resistance between
ropes. In the cut damage test, the results are below.
Cut Damage Tolerance
Percent Strength Retained
Sample
; 4 5 6 7
43 54 100 82
Best Mode
The following is the best mode of the first
embodiment of this invention.
It is believed the most cut resistant structure,
rope, webbing or strap, would use either of the above
described ultrahigh molecular weight polyethylene fibers
as core, either braided or as strands, covered by a jacket
made, preferably braided, from a yarn having the inner
strands of 0.11 mm stainless laid parallel to a strand
of the ultrahigh molecular weight polyethylene fiber of
highest tensile strength (Spectra 1000), the strands being
132~1~3
-14-
wrapped with an inner wrap of the lower tensile strength
polyethylene fiber (Spectra 900) and outer wrap of
polyester fiber described in yarn B, above.
A laboratory study of eleven lines was
undertaken by an independent laboratory to ascertain the
degree of fishbite resistance which each one might have
when used as a deep sea mooring line. In addition to
general considerations based upon the cor,lposition and
construction of the lines, three laboratory tests were
used for objective MeaSUrement of resistance to stabbing
and cutting. Tests were run on the lines when unstressed
and when under a working load.
CONSTRUCTION OF LINES
All of the test lines had cores composed of
parallel synthetic fibers. Six lines had cores of
polyester fiber. Three had cores of Kevlar fiber, and
one had a core of Spectra~ 900.
The cores of lines with polyester cores were
wrapped with a tape of polyester cloth which in turn was
covered by a braided polyester cover. The cores of ropes
from other sources had a wrapping which appeared to be the
same. Table I contains a summary of information on the
test lines. Sample 9 is illustrative of the first
embodiment of the invention herein using polyurethane in
the interstices. All other samples are thought to be
comparative.
TEST METHODS
Resistance to penetration by sharp points was
measured in two ways: 1) using the Shore D scale of a
Durometer (ASTM method #2240), and by stabbing with a
simulated shark tooth of hardened steel as described in
the "Deep-Sea Lines Fishbite Manual" (Prindle & Walden,
1975). Each data point frorn the penetration tests is an
average of five measurements of the force required to
pierce the surface of a line to a standard distance.
Force-to-Cut tests were run on unstressed line
samples using the Baldwin Universal Testing Machine as
described and illustrated in the "Deep-Sea Lines Fishbite
- 15 - 132~
Manual."
In so far as possible within constraints of
time and availability of materials, stab and cut tests
were repeated on the lines loaded with 1125 lbs.
tension. The load was applied by lifting a weight with
the test line. The ends of most rope specimens were
secured by means of a "Chinese finger" method in which
the end of the test line was inserted inside a hollow
braid rope which secured it by friction when tension
was applied. Durometer and Stab tests were run in the
usual ways, but Force-to-Cut tests were done with the
cutting blade mounted in a stirrup which was used to
pull the blade across the test line. This method is
also illustrated in the "Deep-Sea Lines Fishbite
Manual" using a shark jaw as the cutting instrument.
All cutting force data are the result of
single cuts on the lines indicated. These were run on
line samples at ambient conditions of approximately 70
and variable relative humidity.
LALORATORY TEST RESULTS
Data from three previously tested 13/32"
diameter polyester ropes both unprotected and armored
have been added as standards of reference. Of the two
armors, acetal copolymer (CELCON*M25-04) confers a high
degree of bite resistance. When tested at sea, it
proved adequate to protect a line under strong biting
attach. Unfortunately, the Celcon*M25-04 M25-04
formulation cracked during handling so it is not a
practical armor, but it is useful here as an example of
material with the degree of toughness needed. The
second reference line was armored with nylon 6/6 (ZYTEL*
ST 801). It is typical of many plastic covered lines
in that it has good handling qualities but it is less
bite resistant that the acetal copolymer. It is
regarded as a marginal fishbite armor marking the
bottom of the range of acceptable materials. If a
jacket has less stab and cut resistance than nylon 6/6,
it probably would not be a trustworthy barrier against
fishbite damage in all situations.
*Trademark
132~1~3
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Results of the laboratory tests are summarized,
and where available, the generic and trade names of fibers
and plastic jackets are given in Table II. The thickness
of plastic jackets was measured on pieces taken from the
test lines and is noted in parentheses after each generic
name. A few data are missing, as in the case of sample
#1, where the available sample was destroyed in
#6 is a duplicate with a heavier jacket. Problems in
finding adequate terminations for lines #10 were not
resolved in time for this report, so they were not tested
under tension.
EVAL~ATION OF THE LINES
Due to the variety of line constructions, and
the characteristics of test methods, there is no obvious
winner in all categories. To aid in interpreting the
data, tables have been prepared for each test used.
Table III illustrates data obtained with the
Durometer and it is evident that by this test none of the
lines submitted was equal to either of the armored
reference lines i.e. Acetal Copolymer (AC) or Nylon (N),
when tested without tension. The best of the test lines
were #l armored with 47 mils of ionomer, #6 armored with
76 mils of ionomer, and #10 armored with 114 mils of
polyester. The rest were below a level which would seem
to warrant further consideration. However, some mention
should be given to the samples armored with bralds. They
are #7 armored with polyolefin and aluminum braid, #8
armored with Kevlar braid, and #9 armored with
polyurethane and a metal braid. All three ranked low in
the Durometer test, probably because the conical point of
the Durometer slipped between the strands of the braids.
#8, which ranked last in this test, was first in cut
resistance. Hence, it appears that the Durometer test may
be a useful measure of toughness for homogeneous plastic
armors, but is not the whole story when used on items with
a discontinuous cover.
In all cases where lines were tested slack and
again when stressed, the Durorneter readings were either
132~10~
-17-
the same within experimental error or increased when the
line was under tension.
STAB TEST
The single tooth stab test is similar to the
Durometer test in that a point is forced into the line,
but there is the added possibility of cutting by the tooth
edges. Table IV illustrates the relative resistance of
the lines under this test.
When the lines were tested slack, the Acetal
Copolymer (AC) was again the most resistant, requiring 63
lbs. to pierce. Second place went to #10, armored with
114 mils of polyester. It had 70% the resistance of the
acetal copolymer reference line and out performed the
Nylon 6/6 (N) reference standard. Next in line was item
#9, armored with polyurethane and braid. The next few
spots went to items #1, 5, 6, and 7 with only 71~ the stab
resistance of the marginally acceptable nylon 6/6 covered
line.
Tension produced marked changes in the ratings.
#1 spot went to item ~9, urethane and braid armor, which
rose from 35 lbs. resistance to 58 lbs. Under tension, it
was substantially equal to acetal copolymer in the
unstressed condition. With tension, there were 3 lines
closely competitive for second place at a level of about
38 lbs. which is the same as the acetal copolymer
reference line, and better than the nylon 6/6 armored line
at 31 lbs. All three braid-covered lines showed an
increase in resistance to stabbing when a tensile load was
applied.
FORCE TO CUT
In the cutting force test, unlike the others,
progress of the cutting edge can only be made when armor
and fibers have been severed. The test results shown in
Table V are now quite different.
Four of the test lines were more resistant to
cutting than the two reference lines, both in the relaxed
and in the stressed conditions.
With two outstanding exceptions, items #8 and 9,
132~03
-18-
all lines lost cut resistance when tested under tension.
The five lines which were comparable to the nylon 6/6
reference, when tested slack, dropped to levels so low as
to eliminate them from further considera~ion.
CHOICE OF LINES FOR TEST AT SEA
A choice of lines for test at sea is complicated
by variables in line materials and construction. Overall,
there are three kinds of constructions represented:
1. Ropes armored with a layer of plastic only.
2. Ropes covered with a braid only.
3. Ropes jacketed with a combination of braid
- and plastic.
A review of the test data as illustrated in
Tables III, IV and V together with available information
on the lines will show that there is at least one rope in
each category that merits further study.
Taking the lines in order of their overall
resistance to puncture and cutting, the best five lines
are as follows:
Sample 10 - 5/8" dia. Kevlar*rope armored with 114
mils of polyester(I~YTREL)*. This line is bulky and very
stiff. It could only be handled with heavy machinery.
Unfortunately, a method for terminating this line could
not be managed in time for this report, but results on the
unstressed line indicate that it is worth consideration
for further tests.
Sample 9 - 1/4" dia. rope of Spectra~ 900 fiber
coated with a polyurethane over SPECTRA fiber plus metal
core yarn braid jacket. This line is flexible and has
good handling qualities. It is vulnerable to stabbing
when slack but gains resistance when under a working load.
It was superior to the acetal copolymer reference line in
resistance to cutting. 15 Information on the suscep-
tibility to deterioration in sea water is needed tocomplete the information required for an unqualified
recommendation of this line for a test at sea.
Sample 7 - 5/16" dia. KEVLAR*rope with polyolefin
and aluminum braid armor. The armor on this line was
*Trademark
132~1~3
-19-
composed of 35 mils of polyolefin over the KEYLA~*fiber
plus a layer of aluminum braid plus 41 mils of polyolefin.
It was a good handling line albeit a bit stiffer than some
others. The Durometer test was below that of nylon 6/6.
Stab test on the relaxed roye was below that of nylon 6/6
but when the line was loaded it became much more resistant
to stabbing and was about equal to acetal copolymer. In
the cut test, it ranked third when unstressed and when
stressed, it was superior to both of the reference lines.
This is a yood line and worth a test at sea.
Sample 6 - 1/2" dia. polyester fiber (SY~COP~E)*
rope with 76 mils of ionomer SURLYN* jacket. This line
had good handling properties, however, overall it was a
little below the nylon 6/6 reference line in the ~hree
tests. It would be interesting in a test at sea as a line
with minimal resistance for the job of fishbite preven-
tion.
_ Sample 8 - 5/8" dia.KEVLAR* with a coarse KEVLAR
2C braided jacket. This line was interesting in that it was
near the bottom in resistance to penetration, especially -
when slack, however, it was number one in cut resistance.
The effect of tension was to increase its resistance in
all three tests. Loaded, it became so resistant to
cutting that the steel blade was broken before the line
suffered any significant damage. More testing of this
type of line with reference to fishbite is definitely
indicated.
Overall, the results indicate that braids have
interesting properties in resistance to cutting Dut thev
are susceptible to penetration by sharp points especially
when a line is slack. Plastic armors, on the other hand,
lose cut resistance when stretched. Combinations of the
two should probably be investigated further toward making
a line with effective bite resistance under all conditions.
*Trademar~
-20- 132~103
TABLE I
Lines submitted for laboratory tests
Relative to Fishbite resistance
Construction
5 Sample No. Core Jacket (mils)
(All lines parallel
fiber core)
1 1/2" polyester Ionomer (47)
Surlyn
2 " Polyurethane
Texin
3 " Thermoplastic
elastomer (41)
Kraton
4 " Thermoplastic
elastomer (43)
Santoprene
" Polyester (52)
Hytrel
6 " Ionomer (76)
Surlyn
7 5/16" Kevlar Polyolefin and
aluminum braid
8 3/8" Kevlar Kevlar braid
9 1/4" Spectra ~rethane coated
braid~
5/8 Kevlar Polyester (114)
Hytrel
* braid made from yarn of strands of SPECTRA~ fiber
combined with stainless wire, first wrapped with SPECTRA
fiber, then wrapped with polyester fiber.
` -
13251ia3
-21-
TABLE II
Resistance of lines to cutting and stabbing
Sample Construction Durom.-Shore D
Number Core Jacket (mils) Un- 1125 lb.
Stressed Tension
1 1/2" Polyester Ionomer(47) 65 __
2 " Polyurethane
(56) 34 44
3 " Thermoplastic
elastomer(41) 23 28
4 " Thermoplastic
santoprene(43) 19 28
"Polyester (52) 49 52
6 PolyaramideIonomer (76) 65 66
157 5/16" Kevlar Polyolefin and
al~,linum braid 50 51
8 3/8" Kevlar Kevlar braid 14 30
9 1/4" Spectra Polyurethane
coated braid** 46 51
20105/8" Kevlar Polyester (114) 59 --
AC 13/32" Poly-
ester Acetyl copolymer
(7~) 81 --
N " Nylon 6/6 (63) 78 --
250 " None -- --
**See footnote Table I
132~103
-22-
TABLE II (Continued)
Resistance of lines to cutting and stabbing
Sample Stab Force-lbs. Cut Force-lbs.
Number Unstressed 1125 lb. Un- 1125 lb.
TensionStressedTension
1 28 -- 115 --
2 23 31 97 22
3 11 22 98 14
4 12 17 34 6
10 5 27 36 107 23
6 29 38 107 45
7 27 38 306 264
8 13 50 377 >480
g 35 5~ 221 300
1510 44 -- 352 --
AC 63 38* 121 >45*
N 39 31* 104 >37*
O -- -- 14 2*
*1200 lbs. tension on the line
132~1~3
-23-
TABLE III
Durometer Test
ArmorResistance to Reaction
: SampleMaterialDurometer - Shore D
5 No. Thickness Mils Rank Unstressed Under Tension
-
1 47 3 63 --
2 56 8 36 ~3
3 41 9 23 25
4 43 10 19 24
52 6 48 52
6 76 3 63 64
7 -- 5 48 50
8 -- 11 14 26
9 __ 7 44 52
114 4 58 --
AC 78 1 80 --
~ 63 2 78 --
132~103
-24-
Table IV
Stab Test
Sample Force to Stab-lbs.
No. R~nkUnstressed Under Tension
1 6 26 --
2 8 23 31
3 11 12 21
4 10 13 17
7 24 38
6 5 28 38
7 7 24 38
8 9 14 16
9 4 35 58
2 43 --
AC 1 63 38
~ 3 39 31
-25- 13251~3
Table V
Force to Cut
Sample Force to Cut-lbs.
No. Rank Unstressed Under Tension
1 6 110 --
2 10 95 20
3 9 95 15
4 11 25 5
7 105 20
10 6 7 105 30
7 3 310 270
8 1 360 >480
9 4 230 300
2 340 -~
15Unjacketed12 10 5
AC 5 230 >30
N 8 105 >25
132~3
-26-
Example of Second Embodiment
Tests of Cut Resistant Fabrics
Sample A was a knitted glove made from a ECPE
fiber, Spectra 1000. The glove was knitted on a 7 gauge
Shima Seiki glove knitting machine. The yarn used to
produce the glove was composed of 2 ends of 1200 denier
fiber, with 1 turn per inch twist in each fiber end,
resulting in a total yarn denier of 2400. The glove
fabric was approximately 0.045 inches thick, with a weight
of approximately 13.8 oz. per sq. yd.
Sample B was a woven fabric made using glass
fiber (E-glass). The fabric was a satin~weave 57x54,
using 595 denier untwisted glass fiber, with a thickness
of 0.009 inches and a weight of 8.9 oz. per sq. yd.
Sample C was a knitted glove made from the
combination of ECPE fibers (Spectra 1000) and a glass
fiber (E-glass). The yarn used in the glove was
constructed by placing a 595 denier glass fiber and a 650
denier ECPE fiber in the yarn core, with no twist, and
wrapping the core in one direction with 650 denier ECPE
fiber and then wrapping in the other direction with
another 650 denier ECPE fiber. The composite yarn denier
was 2900. The glove was knitted on a 7 gauge Shima Seiki
glove knitting machine. The glove fabric was
approximately 0.055 inches thick, with a weight of
approximately 18 oz. per sq. yd.
The test used to measure the cut resistance of
the mentioned samples is described in U.S. Patent
NO. 4,864,852. The test involves repeatedly
contacting a sample with a sharp edge until the sample is
penetrated by the cutting edge. The higher the number of
cutting cycles (contacts) required to penetrate the
sample, the higher the reported cut resistance of the
sample. During testing, the following conditions were
used: 135 grams cutting weight, mandrel speed of 52 rpm,
rotating steel mandrel diameter of 19 mm, cutting blade
drop height of 9 mm, use of a single-edged industrial
razor blade (Red Devil brand) for cutting, cutting arm
-
132~
-27-
distance from pivot point to center of blade being 6
inches. The two glove fabrics (sample A and C) were
tested by cutting fingers from the gloves and mounting the
finger on the tester mandrel. The fingers were held on
the mandrel with a band clamp placed over the cut end of
the fingers. The woven fabric sample (sample B) was
tested by cutting a 2 by 2 inch piece from the fabric,
wrapping the sample around the tester mandrel and holding
it on the mandrel with adhesive tape. The woven fabric
was mounted so that the cutting blade did not contact the
sample where the mounted fabric edges overlapped. The
cutting cycles reported are an average of multiple tests.
For each test a new, unused razor blade was used so that
the sharpness of the cutting edge was the same for each
test.
Sample A Sample B Sample C
Cutting Cycles to45 1 114
Penetrate Sample
Fabric Thickness 45 9 55
(mils)
Fabric Weight 13.8 8.9 18
(oz/sq. yd.)
Cycles per Thickness 1.0 0.1 2.1
(cycles/mils)
Cycles per Weight3.3 0.1 6.3
(cycles/oz/sq. yd.)
It is surprising that adding glass fiber to ECPE
fibers (sample C) can result in such a large increase in
the cut resistance of the fibers. It is clear that tlle
glass fiber by itself offers very little cut resistance.
The glass fibers are easily broken during the impact of
the cutting process, when used alone. A synergistic
effect is observed when ECPE fibers and glass fiber are
combined to produce a cut resistant yarn.
For this comparative testing, a w~ven glass
fabric was used because of its availability. It would
have been desireable to test a knitted glass fabric as
well. However, glass fibers are difficult to knit due to
- \
132~
-28-
their brittleness and such fabrics were not readily
available. It is not expected that a knitted glass fabric
would have a significantly different level of cut
resistance as compared to a woven glass fabric.
