CA2123263A1 - Uv-resistant and dimensionally stable sail fabric and sail - Google Patents

Abstract

A sail fabric constructed substantially of woven polyethylenenaphthalatebibenzoate (PENBB) yarns. The PENBB yarns of the fabric exhibit very low tenacity loss resulting from UV degradation, and exhibit very good dimensional stability, very low hot air shrinkage and very low creep.

Description

21 2 ~ 3 3 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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' ~ ,:,, ,~' '~1232~3 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 ~g~ 2--~, .~

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21 ~ t3~ 2~.3 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;

Pag- 3 21?,'3~63 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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Pag- 4--/ -212~3 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, ~g- 6--.,' ,... , : ~, ~s ,. ., ,.- ~ :

2~2~63 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 2123~6~

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 P~g- 8--`` 2.~232~3 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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2~ ~326^3 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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Claims (12)

We claim:

1. A sail fabric comprised substantially of woven polyethylenenaphthalatebibenzoate (PENBB) yarns.

2. A sail fabric according to claim 1, wherein said PENBB
yarns of said fabric exhibit a tenacity loss of 5 percent over twenty days resulting from UV degradation when tested in a QUV
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.

3. A sail fabric according to claim 1, wherein said sail fabric comprises a fabric having a construction chosen from the group of fabric constructions consisting of woven, warp-knitted, and warp-only fabric with the warp ends held together by film, and in the instance of a woven fabric, the fabric has a fabric pattern chosen from the group of fabric patterns consisting of plain weave, twill weave and satin weave.

4. A sail fabric according to claim 1, wherein the yarns of said fabric are yarns having a denier of between 50 to 1500.

5. A sail fabric according to claim 4, wherein said fabric exhibits a hot air shrinkage of between .5 and 1.5 percent.

6. A sail fabric according to claim 4, wherein said fabric exhibits warp-wise stretch of approximately 1.3 percent under a wind load of 200 pounds per inch.

7. A sail fabric according to claim 1, wherein the PENBB
yarns are spun yarns.

8. A sail fabric according to claim 1, wherein the PENBB
yarns are drawn yarns.

9. A sail fabric according to claim 7, wherein said spun PENBB yarns exhibit creep of 1.0 percent at 50 percent break load for 2000 hours.

10. A sail fabric according to claim 8, wherein said drawn PENBB yarns exhibit creep of 0.5 percent at 50 percent break load for 2000 hours.

11. A sail fabric according to claim 1, wherein one of the warp or filling yarns are PENa8 yarn3 and the other of the warp or filling yarns are chosen from the group consisting of PET and PPTA
yarns.

12. A sail constructed from the fabric according to claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11.