Coated lightweight fabric, in particular for a spinnaker

Abstract

The invention relates to a fabric for lightweight nautical sails, such as spinnakers, asymmetric spinnakers, and gennakers, for sailboats and other surface vessels, the fabric being formed of continuous polyester warp and weft yarns and being coated on one or both of its two surfaces with a crosslinked polymer, characterised in that the polyester is poly(ethylene terephthalate) (PET) having a tenacity greater than or equal to 6 cN/dtex; in that the fabric has a density of between 20 and 50 threads/cm, in terms of warp and weft density; in that the polymer is a crosslinked polyurethane (PU) that is polyether-, polyester-, or polycarbonate based; and in that this PU is derived from the crosslinking (1) of a single-component polyurethane elastomer having a modulus at 100% elongation comprised between 1 and 15 MPa, better still between 2 and 15 MPa, in particular between 6 and 15 MPa, according to the standard DIN 53504, used in implementation in solvent phase; and (2) by a crosslinking agent, based on a proportion of dry crosslinking agent relative to the dry elastomer of between 20% and 75% by weight, in particular between approximately 30% and approximately 75% by weight. The coated fabric has an elongation in the bias direction under 20 Lbs, comprised between 10 and 30 hundredths of an inch.

Claims

1.-11. (canceled)

12. A fabric for lightweight nautical sails, such as spinnakers, asymmetric spinnakers, and gennakers, for sailboats and other surface vessels, the fabric comprising two surfaces, is formed of continuous polyester warp and weft yarns and is coated on one or both of its two surfaces with a crosslinked polymer, wherein the polyester is poly(ethylene terephthalate) (PET); the PET has a tenacity greater than or equal to 6 cN/dtex ; the fabric has a density of between 20 and 50 threads/cm, in terms of warp and weft density; the polymer is a crosslinked polyurethane (PU) that is polyether-, polyester-, or polycarbonate based; and this PU is derived from the crosslinking (1) of a single-component polyurethane elastomer having a modulus at 100% elongation comprised between 6 and 15 MPa, according to the standard DIN 53504, used in implementation in solvent phase; (2) by a crosslinking agent, based on a proportion of dry crosslinking agent relative to the dry elastomer of between 20% and 75% by weight.

13. The fabric according to claim 12, wherein said single-component polyurethane elastomer has a modulus at 100% elongation comprised between 6 and 10 Mpa, according to the standard DIN 53504.

14. The fabric according to claim 12, wherein said single-component polyurethane elastomer has a modulus at 100% elongation comprised between 6 and 9.5 MPa, according to the standard DIN 53504.

15. The fabric according to claim 12, wherein the proportion of dry crosslinking agent relative to the dry elastomer is between 30% and 75% by weight.

16. The fabric according to claim 12, wherein the proportion of dry crosslinking agent relative to the dry elastomer is between 50% and 75% by weight.

17. The fabric according to claim 12, wherein the PET has a tenacity of between 6 and 7 cN/dtex.

18. The fabric according to claim 12, wherein said fabric has a density of between 25 and 50 threads/cm, in terms of warp and weft density.

19. The fabric according to claim 12, wherein the coated fabric has an elongation in the bias direction under 20 lbs, comprised between 10 and 30 hundredths of an inch, measured on test specimens measuring 76 2 mm in width and 300 mm in length and according to the standard NF EN ISO 13934-1.

20. The fabric according to claim 12, wherein the coated fabric has an elongation in the bias direction under 20 lbs, comprised between 14 and 25 hundredths of an inch, measured on test specimens measuring 76.2 mm in width and 300 mm in length and according to the standard NF EN ISO 13934-1.

21. The fabric according to claim 12, wherein the fabric comprises warp yarns and weft yarns which have a count of between 11 and 235 dtex, with a DPF (decitex per filament) of between 1 and 4.

22. The fabric according to claim 12, wherein the fabric comprises warp yarns and weft yarns which have a count of between 22 and 110 dtex, with a DPF (decitex per filament) of between 1 and 4.

23. The fabric according to claim 12, wherein the fabric comprises warp yarns and weft yarns which have a count of between 22 and 78 dtex, with a DPF (decitex per filament) of between 1 and 4.

24. The fabric according to claim 21, wherein the fabric comprises warp yarns and weft yarns have a DPF (decitex per filament) of between 1.3 and 3.5.

25. The fabric according to claim 12, wherein the PET has an elongation at break greater than or equal to 20%, according to the standard DIN EN ISO 2062.

26. The fabric according to claim 12, wherein the PET has an elongation at break between 20 and 30%, according to the standard DIN EN ISO 2062.

27. The fabric according to claim 12, wherein the rate of dry coating of crosslinked PU relative to the fabric is greater than 5% by weight.

28. The fabric according to claim 12, wherein the rate of dry coating of crosslinked PU relative to the fabric is between 5% and 30% by weight.

29. The fabric according to claim 12, wherein the rate of dry coating of crosslinked PU relative to the fabric is between 10% and 30% by weight.

30. The fabric according to claim 12, wherein the rate of dry coating of crosslinked PU relative to the fabric is between 15% and 25% by weight.

31. The fabric according to claim 12, wherein the weight of the coated fabric is between 25 and 130 g/m.sup.2.

32. The fabric according to claim 12, wherein the crosslinking agent of the elastomer is selected from the group consisting of an isocyanate, a polyisocyanate, melamine, a compound comprising melamine, and a mixture of isocyanate and melamine

33. The fabric according to claim 32, wherein said isocyanate and said polyisocyanate, is aliphatic.

34. A lightweight nautical sail which comprises at least one fabric according to claim 12.

35. The lightweight nautical sail according to claim 12, which sail is selected from the group consisting of a spinnaker, an asymmetric spinnaker, and a gennaker.

36. The lightweight nautical sail according to claim 34, wherein said sail bears a pattern that is sublimation printed.

37. A fabric production method for producing a coated fabric according to claim 12, comprising the following steps: a fabric is provided, which is made of poly(ethylene terephthalate) (PET) having a density of between 20 and 50 threads/cm, in terms of warp and weft density; and the PET has a tenacity greater than or equal to 6 cN/dtex; said fabric has two surfaces, one or both of these two surfaces is/are coated making use of a mixture of: a single-component polyurethane elastomer having a modulus at 100% elongation comprised between 6 and 15 MPa, according to the standard DIN 53504; a solvent for the elastomer; and a crosslinking agent; based on a proportion of dry crosslinking agent relative to the dry elastomer of between 20% and 75% by weight; the fabric is heated until drying and crosslinking of the coating; a coated fabric is obtained; optionally, the fabric is printed by sublimation, on one or both of its two surfaces.

Description

EXAMPLE

Example 1

[0065] This example compares the impact of a polyurethane coating on conventional polyamide 6.6 fabrics coated with PU (Control) and high tenacity polyethylene terephthalate (PET) fabrics coated on one surface with a PU according to the invention.

[0066] PA6.6 is a conventional polyamide fabric in the spinnaker industry, with a PU coating obtained from PU elastomer having a 100% elongation modulus of 32.4 and melamine formaldehyde crosslinking agent. The proportion of dry crosslinking agent relative to the dry elastomer is 104%. The PU is used in a 50/50 mixture of toluene and isopropanol.

[0067] The PET has a PU coating obtained from PU elastomer having a 100% elongation modulus of 8, and melamine formaldehyde crosslinker. The proportion of dry crosslinking agent relative to the dry elastomer is 66.9%. The PU is used in a 50/50 mixture of toluene and isopropanol.

[0068] The tenacity of PET is 6.8 cN/dtex. The elongation at break is 24.6%.

[0069] The coating is effected by using a doctor blade, and is followed by a step of drying at 100° C., and then a step of crosslinking at 170° C. The speed is 27 m/min.

TABLE-US-00001 TABLE 1 Invention - Control Example 1 Type of yarn PA6.6 PET Count (dtex) 33 33 DPF 3.3 2.1 Number of warp yarns × weft yarns 44 × 45 44 × 44.5 PU modulus at 100% elongation (MPa) - 32.4 8 standard DIN 53504 % crosslinking agent (in dry weight) 104 66.9 Weight (g/m.sup.2) - ISO2286-2 41.2 38.4 Bias elongation under 20 Lbs (in 100.sup.ths inch) 10.9 20.1 Warp elongation under 20 Lbs (in 100.sup.ths inch) 13.7 10.6 Weft elongation under 20 Lbs (in 100.sup.ths inch) 16.8 5.7 Breaking strength Warp (daN/5 cm) - 42.6 38.5 NF EN ISO 13934-1 Breaking strength Weft (daN/5 cm) - 41.5 44.4 NF EN ISO 13934-1 Tear resistance Warp (Lbs) - NF EN ISO 13937-2 5.7 5.3 Tear resistance Weft (Lbs) - NF EN ISO 13937-2 4.9 5.4 Water absorption - new (%) 0.3 0.02 Water absorption - post aging (%) 1.1 0.1

TABLE-US-00002 TABLE 2 Invention - Control Example 2 Type of yarn PA6.6 PET Count (dtex) 50 44 DPF 3.8 3.2 Number of warp yarns × weft yarns 42 × 42 39.3 × 39 PU modulus at 100% elongation (MPa) - 32.4 8 standard DIN 53504 % crosslinking agent (in dry weight) 104 66.9 Weight (g/m.sup.2) - ISO2286-2 55.0 47.0 Bias elongation under 20 Lbs (in 100.sup.ths inch) 9.3 16.1 Warp elongation under 20 Lbs (in 100.sup.ths inch) 9.8 9.3 Weft elongation under 20 Lbs (in 100.sup.ths inch) 13.3 7.9 Breaking strength Warp (daN/5 cm) - 63.2 50.9 NF EN ISO 13934-1 Breaking strength Weft (daN/5 cm) - 58.6 48.9 NF EN ISO 13934-1 Tear resistance Warp (Lbs) - NF EN ISO 13937-2 7.4 14.1 Tear resistance Weft (Lbs) - NF EN ISO 13937-2 5.6 12.8

Example 2

[0070] The fabric of the invention from Example 1 made of 33 dtex yarns is taken and compared with counter-examples 1 and 2, which differ therefrom by combinations of the modulus of the PU and proportion of crosslinking agent which are outside the limits of the invention.

TABLE-US-00003 TABLE 3 Invention Counter- Counter- Example Example Example 1 1 2 Type of yarn PET PET PET Count (dtex) 33 33 33 DPF 2.1 2.1 2.1 Number of warp yarns × weft yarns 44 × 44.5 44 × 44.5 44 × 44.5 PU modulus at 100% elongation 8 2 8 (MPa) - standard DIN 53504 % crosslinking agent (in dry 66.9 15.4 16.5 weight) Weight (g/m.sup.2) - ISO2286-2 38.4 38.6 38.5 Bias elongation under 20 Lbs (in 20.1 53.8 47.4 100.sup.ths inch) Warp elongation under 20 Lbs (in 10.6 8.8 10.4 100.sup.ths inch) Weft elongation under 20 Lbs (in 5.7 6.6 6.3 100.sup.ths inch) Breaking strength Warp (daN/5 cm) - 38.5 39.4 39.7 NF EN ISO 13934-1 Breaking strength Weft (daN/5 cm) - 44.4 40.4 43.3 NF EN ISO 13934-1 Tear resistance Warp (Lbs) - NF 5.3 9.7 7.5 EN ISO 13937-2 Tear resistance Weft (Lbs) - NF EN 5.4 9.5 8.0 ISO 13937-2 Water absorption - new (%) 0.02 0.4 0.1 Water absorption - post aging (%) 0.1 0.9 0.2

[0071] Methods and Measurements Used in the Application (Characteristic Features of the Invention and Examples):

[0072] NF EN ISO 2062—Determination of the breaking strength and elongation at break of individual yarns making use of a constant rate of elongation test apparatus, using Method A of the standard.

[0073] Breaking force (unit centiNewton—cN): maximum force developed to break the sample during a tensile test leading to breakage

[0074] Elongation at break (%): increase in the length of the sample measured at breaking of the latter

[0075] Tenacity (cN/tex): quotient of the breaking force expressed in cN by the linear density of the yarn expressed in dtex (1 tex=1 g per 1000 m of yarn length).

[0076] The test makes it possible to measure the force and the elongation at break of the sample, characteristic variables of the yarn.

[0077] The yarn is placed between two fixing clamps, spaced apart by 500 mm. The apparatus (Dynamometer) then moves the clamps away from each other at a constant displacement speed of 500 mm/min and measures the applied force continuously. The force required to break the yarn is measured as well as the increase in length of the yarn upon breaking.

[0078] The mean breaking strength and mean elongation at break are the two data items characterised by this test. The tenacity is calculated based on dividing the breaking force by the linear density.

[0079] The modulus at 100% elongation of the single-component polyurethane elastomer is measured according to the standard DIN 53504. The modulus is defined in 3.4 of the standard “Spannungswerte”. The measurement is carried out on test specimens that are dumbbell-shaped (Schulterstab) of type S2, however with a bar length I.sub.S of 55 mm and a thickness of 200 μm. The equipment used is a dynamometer. The dumbbell specimen is placed in the fixing clamps, spaced apart by a length L.sub.0 with the minimum possible pre-tension. The clamps are then moved away from each other at a constant speed of 400 mm/min and the dynamometer measures the force applied as a function of the elongation. The modulus or stress at 100% elongation in MPa is the force ratio measured at 100% elongation on the initial section of the specimen. This is described in paragraph 9.4 Spannungswerte of the standard DIN 53504.

[0080] The elongations of the fabric are measured according to the standard NF EN ISO 13934-1, as described in the general description. The lesser elongation in the direction of the warp and weft yarns due to the polyester nature is compensated by a greater elongation in the bias (measured herein in the warp direction). This elongation in the bias effectively serves to compensate for the excessive rigidity of the PET and enables avoiding the risks of breaking and bursting under high stresses. The mechanical performance results are equivalent or indeed even superior, this consequently leads to a polyester fabric that is suitable for use in spinnaker production.

[0081] The absorption of water by the coated fabric of Example 1 was measured according to the standard Tappi 441 om-90. One measurement was performed on the new coated fabric, with another performed post aging. The measurement is expressed in percentage. The equipment consists of a square rubber substrate and a metal ring clad at its base with a rubber gasket. The sample is placed on the square substrate and the metal ring is placed on the sample. A clamping device is used to make the system watertight. A certain quantity of water (100 ml) is placed in the ring, in contact with the sample for a determined time (1 minute). When the time has elapsed, the water is removed from the cylindrical ring, the water residue remaining on the surface of the sample is removed by using a cylinder as described in the standard, via a to-and-fro movement of this cylinder over the sample placed between two blotters, without applying pressure. The percentage of water absorbed is determined by calculating the difference in weight before and after the contact with water.

[0082] For the aging, the fabric is placed for 4 hours in a ‘Cocotte Minute’ pressure cooker with salted water (30 g/l) at operating temperature and pressure. Subsequently 1 hour of treatment is applied by floating the fabric in open air and at high speed, the fabric being fixed to a mill-type assembly (4 blade assembly, the fabric being fixed to the end of one of the blades).

[0083] It is thus demonstrated that the fabric according to the invention undergoes practically no unfavourable evolution in terms of its water absorption after aging. This level of resistance to water uptake is another surprising positive result.