Polyester fabric for a boat traction structure

Abstract

A fabric for a ship traction structure, formed from multifilament continuous warp yarns and weft yarns and coated on one or both of its two surfaces with a polyurethane (PU), the bare fabric having a coverage rate TC of between 1.8 and 4, the yarns being made of poly(ethylene terephthalate) (PET), the fabric having a density of between 20 and 50 yarns/cm, in terms of warp and weft density, the polyurethane being a crosslinked PU that is polyether-, polyester-, or polycarbonate-based, and this PU being derived from the crosslinking (1) of a single-component polyurethane having a modulus at 100% elongation less than or equal to 5 MPa, in particular between 1 and 4 MPa, in particular between 1 and 3 MPa, according to the standard DIN 53504, implemented in organic solvent phase; (2) by a crosslinking agent, based on a proportion of dry crosslinking agent relative to the dry elastomer of between approximately 5% and approximately 30% by weight, the fabric having a weight, coating included, ranging from 43 or 44 to 250 g/m.sup.2. A ship traction structure, in particular of the paraglider sail type, made with such a fabric.

Claims

1.-13. (canceled)

14. An aerial traction structure for a ship, comprising at least one layer of a coated fabric made of a bare fabric having two surfaces and formed from multifilament continuous warp yarns and weft yarns and coated on one or both of its two surfaces with a polyurethane (PU) as a coating material, wherein the bare fabric has a coverage rate TC of between 1.8 and 4, the TC being calculated according to the formula TC=(number of filaments/cmdiameter of 1 filament in cm).sub.warp+(number of filaments/cmdiameter of 1 filament in cm).sub.weft, the yarns are made of poly(ethylene terephthalate) (PET), the bare fabric comprises or is made up of warp yarns and weft yarns that have a dtex of between 33 and 470 dtex and has a density of between 20 and 50 yarns/cm, in terms of warp and weft density, the polyurethane is a crosslinked PU that is polyether-, polyester-, or polycarbonate based, and this PU is obtained by the crosslinking (1) of a single-component polyurethane having a modulus at 100% elongation less than or equal to 5 MPa, according to the standard DIN 53504, used in implementation in organic solvent phase; (2) by a crosslinking agent, based on a proportion of dry crosslinking agent relative to the dry elastomer of between 5% and 30% by weight, and the coated fabric has a weight, including coating, ranging from 43 to 250 g/m.sup.2.

15. The structure according to claim 14, wherein the bare fabric has a coverage rate TC of between 2.6 and 3.2.

16. The structure according to claim 14, wherein the single-component polyurethane has a modulus at 100% elongation of between 1 and 4 MPa, according to the standard DIN 53504.

17. The structure according to claim 14, wherein the single-component polyurethane has a modulus at 100% elongation of between 1 and 3 MPa, according to the standard DIN 53504.

18. The structure according to claim 14, wherein the proportion of dry crosslinking agent relative to the dry elastomer is between 7 and 20% by weight.

19. The structure according to claim 14, wherein the tenacity of the PET yarns is greater than or equal to 6 cN/dtex, and the elongation at break of these PET yarns is greater than or equal to 20%, according to the standard DIN EN ISO 2062.

20. The structure according to claim 14, wherein the tenacity of the PET yarns is between 6 and 7 cN/dtex, and the elongation at break of these PET yarns is between 20% and 30%, according to the standard DIN EN ISO 2062.

21. The structure according to claim 14, wherein the coated fabric has a weight, including coating, ranging from 44 to 250 g/m.sup.2.

22. The structure according to claim 14, wherein the coated fabric has a weight, including coating, ranging from 44 to 130 g/m.sup.2.

23. The structure according to claim 14, wherein the dry uptake rate of the coating material is between 10 and 35% by weight.

24. The structure according to claim 14, wherein the bare fabric comprises or is made up of warp yarns and weft yarns that have a dtex of between 33 and 470 dtex, with a DPF (decitex per filament) of between 1 and 4.

25. The structure according to claim 14, wherein the crosslinking agent of the PU is an isocyanate, a polyisocyanate, melamine, a compound comprising melamine, or a mixture of isocyanate and melamine.

26. The structure according to claim 14, wherein the coated fabric has an air permeability of less than or equal to 20 L/m.sup.2/min under a pressure of 2000 Pa, as measured according to standard NFG 07111 over a measurement surface area of 100 cm.sup.2, and/or water absorption according to the standard Tappi 441 om-90 of less than or equal to 1%, whether new or post aging.

27. The structure according to claim 14, wherein the coated fabric has an elongation in the bias along the warp and weft directions under 1.36 kg, that is less than or equal to 10%, according to the standard NF EN ISO 13934-1.

28. The structure according to claim 14, wherein the coated fabric has an elongation in the bias along the warp and weft directions under 1.36 kg, that is between 1% and 10%, according to the standard NF EN ISO 13934-1.

29. The structure according to claim 14, wherein the coated fabric bears a pattern printed by sublimation.

30. The structure according to claim 14, wherein it has a structure of paraglider sail with box section type, including a lower surface and an upper surface, the lower surface and the upper surface being made with this coated fabric.

31. The structure according to claim 30, wherein the lower surface and the upper surface have a surface area of between 50 and 800 m.sup.2.

32. A method for manufacturing an aerial traction structure for a ship according to claim 14, comprising manufacturing a coated fabric, said manufacturing comprising: providing a bare fabric having two surfaces, said fabric being made of poly(ethylene terephthalate) (PET) having a density of between 20 and 50 yarns/cm, in terms of warp and weft density; wherein one or both of the two surfaces of this fabric is/are coated making use of a mixture comprising a single-component polyurethane elastomer having a modulus at 100% elongation less than or equal to 5 MPa, according to 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 5% and 30% by weight; and heating the fabric with said mixture until drying and crosslinking of the coating so that a coated fabric is obtained; wherein all or part of the aerial structure is made with this coated fabric.

Description

EXAMPLES 1 AND 1BIS

[0088] These examples compare the impact of a polyurethane coating on one surface of a conventional polyamide 6.6 fabric coated with stiff PU (Control 1), a polyester fabric coated with stuff PU on one surface (Control 2) and high tenacity polyethylene terephthalate (PET) fabrics coated on one surface with a PU (examples according to invention).

[0089] Control 1: PA6.6 is a conventional polyamide fabric in the spinnaker field, with a PU coating obtained from PU elastomer having a modulus at 100% elongation of 8 MPa and isocyanate+melamine formaldehyde crosslinking agent. 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.

[0090] Control 2: a PU coating obtained from PU elastomer having a modulus at 100% elongation of 32.4 MPa and isocyanate+melamine formaldehyde crosslinking agent. The proportion of dry crosslinking agent relative to the dry elastomer is 137%. The PU is used in a 50/50 mixture of toluene and isopropanol.

[0091] The PET has a PU coating obtained from PU elastomer having a modulus at 100% elongation of 2 MPa and isocyanate+melamine formaldehyde crosslinking agent. The proportion of dry crosslinking agent relative to the dry elastomer is 8.4%. Examples 1 and 1bis differ by the dry uptake rate of the coating material. The PU is used in a 50/50 mixture of toluene and isopropanol.

[0092] In both controls and in the example of the invention, the PU is a single-component PU that is aliphatic polycarbonate based.

[0093] The tenacity of the PET is 6.6 cN/dtex. The elongation at break is 21%.

[0094] 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 180 C. The speed is 27 m/min.

TABLE-US-00001 TABLE 1 Example 1 Example 1bis According to According to Control 1 Control 2 the invention the invention Type of yarn PA6.6 PET PET PET Count (dtex) (warp and 110 114 114 114 weft) DPF 3.2 3.6 3.6 3.6 Number of warp yarns 35 30.0 33.6 30.5 33.6 30.5 33.6 30.5 weft yarns Coated weight (g/m.sup.2) 85.2 84 90 100 Dry uptake rate of the 9.3 9.4 13.2 22.7 coating material (%) Porosity - new (L/m.sup.2/min) 5 6 2 2 Porosity - post aging 44 >200 7 2 (L/M.sup.2/min) Water absorption - new 0.2 0.1 0.1 0.1 (%) Water absorption - post 1.8 1.3 0.7 0.7 aging (%) Elongation in the bias 0.9 0.5 4.1 3.6 under 3 lbs or 1.36 kg (%) Methods for measuring the porosity and the water absorption outlined later.

Examples 2 and 2Bis

[0095] These examples compare the impact of a polyurethane coating on one surface of a conventional polyamide 6.6 fabric coated with stiff PU (Control 3), a polyester fabric coated with stuff PU on one surface (Control 4) and high tenacity polyethylene terephthalate (PET) fabrics coated on one surface with a PU (examples according to invention).

[0096] Control 3: PA6.6 is a conventional polyamide fabric in the spinnaker field, with a PU coating obtained from PU elastomer having a modulus at 100% elongation of 8 MPa and isocyanate+melamine formaldehyde crosslinking agent. 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.

[0097] Control 4: a PU coating obtained from PU elastomer having a modulus at 100% elongation of 8 MPa and isocyanate+melamine formaldehyde crosslinking agent. 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.

[0098] The PET has a PU coating obtained from PU elastomer having a modulus at 100% elongation of 2 MPa and isocyanate+melamine formaldehyde crosslinking agent. The proportion of dry crosslinking agent relative to the dry elastomer is 15.4% for example 2 and 8.4% for example 2bis. Examples 2 and 2bis also differ by the dry uptake rate of the coating material. The PU is used in a 50/50 mixture of toluene and isopropanol.

[0099] In both controls and in the example of the invention, the PU is a single-component PU that is aliphatic polycarbonate based.

[0100] The tenacity of the PET is 6.6 cN/dtex. The elongation at break is 21%.

[0101] 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 180 C. The speed is 27 m/min.

TABLE-US-00002 TABLE 2 Example 2 Example 2bis According to According to Control 3 Control 4 the invention the invention Type of yarn PA6.6 PET PET PET Count (dtex) (warp and 50 44 44 44 weft) DPF 3.8 3.2 3.2 3.2 Number of warp yarns 42 42 39.3 39 39.3 39 39.3 39 weft yarns Coated weight (g/m.sup.2) 54.8 47 44.9 52 Dry uptake rate of the 15.4 21.9 18.0 30.0 coating material (%) Porosity - new (L/m.sup.2/min) 5 2 2 2 Porosity - post aging 75 >200 27 4 (L/M.sup.2/min) Water absorption (%) 0.2 0.1 0.1 0.1 Water absorption - post 0.8 0.3 0.2 0.2 aging (%) Elongation in the bias 1.2 0.9 3.2 8.9 under 3 lbs or 1.36 kg (%) Methods for measuring the porosity and the water absorption outlined later.

Conclusions on the Two Examples:

[0102] The PA6.6 substrate is not ideal because of its higher water uptake after aging. The coated fabrics according to the invention have good porosity (air permeability) properties, and this good porosity is stable, as demonstrated by the test with aging. The superior test across the bias for the fabrics according to the invention contributes to this maintenance of the porosity. The fabrics of the invention also have the best behavior in terms of water absorption when new and after aging. These properties make these fabrics suitable for use to form aerial traction structures used in a marine environment.

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

[0103] 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. [0104] Breaking force (unit centiNewtoncN): maximum force developed to break the sample during a tensile test leading to breakage [0105] Elongation at break (%): increase in the length of the sample measured at breakage of the latter [0106] 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). [0107] The test makes it possible to measure the force and the elongation at break of the sample, characteristic variables of the yarn. [0108] 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 breakage.

[0109] The mean breaking force and mean elongation at break are the two data items characterized by this test. The tenacity is calculated based on dividing the breaking force by the linear density.

[0110] 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 Is of 55 mm and a thickness of 200 m. The equipment used is a dynamometer. The dumbbell specimen is placed in the fixing clamps, spaced apart by a length Lo 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 test specimen. This is described in paragraph 9.4 Spannungswerte of the standard DIN 53504.

[0111] The porosity (air permeability) and water absorption are to be, and have been evaluated when new and post aging.

[0112] For the aging, the porosity of the fabric after hydrolysis is also measured. In order to do this, the fabric is placed for 4 hours in a Cocotte Minute pressure cooker with saltwater at 30 g/l at operating temperature and pressure. Subsequently, 30 minutes 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).

[0113] The water absorption when new and post aging is to be and has been measured according to the Tappi 441 om-90 standard. It 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.

[0114] The porosity is to be, and has been measured when new and post aging in accordance with standard NFG 07111 or the standard NF EN ISO 9237-Determination of the air permeability of fabrics; the latter replacing the former, however giving identical results. The sample is mounted on a circular sample holder. A suction is started in order to create a depression of 2000 Pa which induces an air flow through the sample. The flow rate of this flow is measured and given in L/m.sup.2/min.

[0115] The elongation in percentage of the fabric is to be measured, and has been measured, under a force of 3 pounds (lbs) or 1.36 kg, applied across the bias. This elongation characterizes the stiffness of the fabric across the bias. The standard used is NF EN ISO 13934-1. Test specimens measuring 50 mm in width and 300 mm in length are to be, or have been, produced. The clamp jaws of the dynamometer are moved away from each other by 200 mm and the measurement is to be, and has been performed at a speed of 100 mm/min.