Note: Descriptions are shown in the official language in which they were submitted.
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W-RES~ ~ FA~RI5_~CL
Technical_~iel~ an~ Bac~q~Qyn~Lof the Inyen~lon
This invention relates to a sail ~abric and sails which
exhibit extremely good resistance to ultraviolet (W) light and
which also provide good dimensional stability. By "dimensional
, stability" is meant cloth that has high resistance to creep and
therefore resists changes in shape during use. These are
characteristics which enhance the performance and durability of
sails, particularly when used on vessels whero improvements in sail
performance and value are important. As is evident, resistance to
ultraviolet light prolongs other performance-enhancing
characteristics which are engineered into the fabric.
The sail fabric from which the sails are fabricated is
woven of yarns spun or drawn from polyethylenenaphthalatebibenzoate
tPENB~) fibers. This fiber and its synthesis is described in
applicant's published PCT Application No. WO 93/02122. Research
into the properti-s and charactQristics of PENBB fibers has
demonstrated that certain such properties and characteristics lend
themselves to application in high performance sails. PENBB fiber
sail fabric exhibits many of the advantageous characteristics of
polyethyleneteraphthalate (PET), such as light wei~ht and good
strength, while substantially exceeding other PET fiber
charactQristics which have heretofore boen barriers to optimal sail
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performance. Presently, the lower-priced end o~ the sail market
is dominated by PET-fiber sails, with the higher-priced end o~ the
market is dominated by poly(para-phenylene terephathalamide (PPTA),
sold under the trademark "Xevlar". PET sailcloth exhi'aits
satisfactory W results when treated with surface-coated resins or
films. PPTA sails exhibit poor W results even if treated with
surface-coated resins or films.
For example, PET ~iber is known to exhibit very poor W
stability. Sç~, I. Ouchi et al, 20 J. A~lied Poly~çr Scie~ce
(1976) at 1983. In contrast, PENBB exhibits exceptional W
stability.
Japanese Patent No. 4272250 discloses a sail cloth with
good light fastness characteristics, which includes a warp and
filling of multifilament yarn composed of PET-containing UV
absorbers of benzophenone and benzotriazole. The cloth comprises
warp and filling of multifilament yarn of PET, or of main component
of PET, containing 0.05-2 wt.S of a W a'a~orber of benzotriazole
and 0.05-2 wt.% of a UV absorber of benzophenone. Each cover factor
of warp and filling i~ preferably 1200-2600, and sum af the two
cover factors is more than 2800. The sail cloth is resin finished,
using preferably a polyester-, melamine-, urethane-resin.
Japane~e Patent No. 3193912 discloses a light resistant
polyestQr fiber which contains PET, benzotriazole and benzophenone
W adsorbQnts, used as seat belt, sailcloth, rope and the like.
The fiber is composed of polyester comprising PET or PET as the
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main component and also containing 0.05-2wt.% oS benzotriazole type
W absorbent and 0.05-2wt.% o~ benzophenone type W absorbent.
Japanese Patent No. 3097964 discloses a sailcloth with
high resistance to weathering. The sailcloth comprises a sheet of
plane-weave fabric of polyester filament coated with W shielding
agent. A film of a synthetic resin containing a W -absorbing-agent
of mol.wt. more than 300 and/or a W-~hielding-agent, is coated
onto both sides of surface of the sheet. The W absorbent is
preferably benzotriazole. The fabric is preferably - --
polybutyleneterephthalate, of ~etween 100-500 denier. The synthetic
resin is preferably melamine-, urea-, epoxy-,phenol-, poly -
urethane-, polyester-, polyvinylalcohol-, vinylacetate-resin.
~umma.~y of the Invention
Therefore, it is an object of the invention to provide
a sail fabric and sail which exhibits excellent resistance to
ultraviolet light.
It is another object of the invention to provide a sail
~abric and sail which has a much higher initial modulus than PET.
It is another object of the invention to provide a sail
fabric and sail which haa excellent dimensional stability.
It i9 another object of the invention to provide a sail
fabric and 5ail which has low creep;
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It is another object of the invention to provide a sail
fabric and sail which has excellent high temperature property
retention;
It is another object of the invention to provide a sail
fabric and sail which has very low hot air shrinkage.
These and other objects of the present invention are
achieved in the preferred embodiments disclosed below by
providing a sail fabric comprised substantially of woven
polyethylenenaphthalatebibenzoate (PENBB) yarns.
According to one preferred embodiment of the invention,
said PENBB yarns of ~aid fabric exhibit a tenacity loss of 5
percent over twenty days resulting from W degradation when tested
in a QW weatherometer in accordance with ASTM G-53, and a tenacity
loss of 40 percent when tested in a Xenon weatherometer in
accordance with ASTM G-53.
According to another preferred embodiment of the
invention, the sail fabric compri~es a plain weave fabric having
34 picks per inch and 34 warp ends per inch.
According to yet another preferred embodiment of the
invention, the yarns of said fabric are 750 denier.
According to yet another preferred em~odiment of the
invention, the fabric exhibits a hot air shrinkage of between .5
and 1.5 percent.
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It is another object of the invention to provide a ~abric
which exhi~its warp-wise stretch of approximately 1.3 percent under
a Ioad of 200 pounds per inch (35 kg per cm).
Accordinq to yet another preferred embodiment of the
invention, the PENBB yarns are spun yarns. ~ -
According to yet another pre~erred embodiment of the
invention, the PEN~B yarns are drawn yarns.
According to yet another preferred embodiment of the
invention, said spun PENBB yarns exhibit creep of 1.0 percent at
lo 50 percent break load for 2000 hours.
According to yet another preferred embodiment of the
invention, said drawn PENB8 yarns exhibit creep of 0.5 percent at
50 percent break load for 2000 hours.
According to yet another preferred embodiment of the
invention, the sail fabric according to the various embodiments
described in the application is constructed into a sail.
Brief DessL~ sn-D~ t~_nDaliL9~
Some of the objects of the invention have been set forth ~ -
above. Othor objocts and advantages of the invention will appear
as the invention procoeds when taken in conjunction with the
followinq drawinqs, in which~
Figure 1 is a overall perspective view of a sailing
vessol riggod with sails according to the present invention;
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Figure 2 is a chart plotting tenacity vs. elongation o~
PENBB spun fiber in comparison with PET;
Fiqure 3 i8 a table illustrating efrects on various
physical characteristics of yarns exposed to W in a Q W
s Weatherometer~
Figure 4 is a table illustrating effects on various
physical characteristics of yarns expo~ed to W in a Xenon
Weatherometer;
Figure 5 is a chart plotting W Stability of PENBB, PET
and PEN yarns in terms of yarn tenacity vs. W exposure time;
Figure 6 is a chart plotting W Stability of PENBB, P~T
and PEN yarns in terms of percent tenacity retention vs. exposure
time.
~escriptio~ of_5bçLE~fe~ odi~e~t and Best Mode
Referring now specifically to the drawings, a sail
constructed of a fabric according to the present invention is
illustrated in Figure 1 and shown generally at reference numeral
10. The sail~ ~0 are fabricatsd according to conventional sail
construction techniques. The sails 10 can replace sails heretofore
fabricated from PET or PPTA yarns. Sails 10 exhibit the desireable
characteristics, i~, light weight, ease of handling and non-
~oisture absorbency, of PET while exhibiting other characteristics,
e., superior W resistance and very good dimensional stability,
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which have heretofore generally unsati3factory characteristics o~
PET~fiber sailcloth.
Fabrication of the sail~ 10 of PENBB basically involves
substitution of PENBB yarns for PET yarns--the respective fibers
being sufficiently similar in overall mechanical respects that
changes in fabric design and conctruction will ordinarily be
minimal. The differences in the two fibers--PENBB and PET--exhibit
themselves in two primary ~odes. First, PENBB fibers and yarns
exhibit greatly enhanced dimensional stability which directly
results in an improvement in sail performance at any given time.
Second, the inherent superior W resistance permits the improved
sail performance at any given time to extend substantially beyond
the point in time when PET sails would have deteriorated to the
point of needing replacement.
Example
A suitable sailcloth construction using PENBB yarns would
be a fabric having 34 picks per inch and 34 warp ends per inch in
a plain weave patt~rn, using 750 denier PENBB spun yarns without
yarn twist. PET film is coated onto the fabric to prevent air
permeation. The 750 denier PENBB spun yarn has the following
properties:
Denier per ~ilament 10
Tenacity (g/den) 8.4
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Initial Modulus ~g/d~n) 300
Elongation (%) 5
Hot Air Shrinkage 0.5% at 177 C
Properties of P~NBB are also shown in the several drawing
s figures. For example, in Figure 2 a comparison is shown between
the tenacity and elongation of PENBB and PET fibers. For example,
a force of 5 grams per denier on PENBB will result in an elongation
of 2 percent, whereas a liXe force on PET results in an elongation
of approximately 5.5 percent. A force of 8 grams per denier on
PENBB will result in an elongation of 4 percent, whereas a like
force on PET results in an elongation oS approximately 10 percent.
Further~ore, note that at elongations of more than 9 percent, PET
exhibits a su~stantial reduction in tenacity.
In a hypothetical example, a wind pressure of 200 pounds
per inch will stretch a conventional PET sail by 4 percent in the
warp direction, but will stretch a PEN~B sail of similar
construction by only 1.3 percent or less. Thus, dimensional
stability is three times greator for PENBB as contrasted with PET
sails .
The effect of W radiation on PENBB and PET fibers is
shown in Figures 3 and 4.
In Figure 3, the e~fects of a QW Weathering Study
comparing PENBB, PET and PEN (polyethylenenaphthalate) yarns is
shown. Note the dramatic differences between the percent change
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in initial modulus, break tenacity and elongation at break betwe-n
PENBB and PET--particularly at 10 and 20 days.
In Figure 4, similar e~ects are noted in a Xenon
weathering study which more clo~ely approximates sunlight than the
s QW Study of Figure 3. Note again the dramatic differences in the
percent change in initial modulus, breaX tenacity and elongation
at break between PENBB and PET--particularly at 10 and 20 days.
The results of Figure 3 is plotted in Figures 5 and 6.
Note the dramatic differences between PENBB and PET yarns.
The~e differences tran~late directly into substantially
improved ~ervice life for the sails 10. In particular, hot air
shrinkage is substantially improved, with values of .5 to 1.5
percent hot air shrinkage at 177 C., as contrasted with 5.4
percent or greater for PET.
It is known that as typically used, stretch in sails does
not often exceed 1.0 percent. It has been determined that fabrics ~
woven from PENBB yarns exhibit much greater dimensional stability ;
in the first 1 percent of stretch that similar fabrics of PET.
Creep resistance tests also show that at a 50 percent of
Z0 break load for Z000 hours, PET yarns crept 1.5 percent, PENBB spun
yarn 1.0 percent and PENBB drawn yarn 0.5 percent. The creep test
was conducted by measuring the change in distance between two
defined points on a loaded, vertically hung sample. The PENBB
samples tested were 80 inchs long, with no twist, and were loaded
with 50~ of their breaking loads. ;
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A sailcloth and sail i5 described above. Various details
of the invention may be changed without departing from its scope.
Furthermore, the foregoing description of the preforred embodiment
of the invention and the best ~ode for practicing the invention are
S provided for the purpose of illustration only and not for the
purpose of limitation--the invention being defined by the claims.
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