Coated lightweight fabric, in particular for a spinnaker

Abstract

The invention relates to a fabric for lightweight nautical sails for sailboats and other surface vessels, such as spinnakers, asymmetric spinnakers, and gennakers, the fabric being formed from warp yarns and continuous weft yarns made of polyester and being coated on one or both faces with a crosslinked polymer, characterized in that the polyester is polyethylene terephthalate (PET) having a tenacity of 6 cN / dtex or more, in that the fabric has a density of between 20 and 50 yarns / cm in warp and weft, in that the polymer is a polyether-, polyester- or polycarbonate-based cross-linked polyurethane (PU), and in that said PU is derived from the cross-linking (1) of a one-component polyurethane elastomer having a modulus at 100% elongation of between 1 and 15 MPa, better still between 2 and 15 MPa, in particular between 6 and 15 MPa, according to standard DIN 53504, carried out in a solvent phase, and (2) by a cross-linking agent, with a proportion of dry cross-linking agent relative to dry elastomer of between 20% and 75% by weight, in particular between approximately 30 and approximately 75%. The coated fabric has a bias extension at 20 Lbs of between 10 and 30 1 / 100 inch.

Description

[0001] The present invention relates to a lightweight fabric formed from continuous warp and weft threads, this fabric being coated on one and / or both sides with a polyurethane. This lightweight fabric finds its application in particular in the field of lightweight headsails of sailing boats and other surface vessels, such as spinnakers, asymmetric spinnakers, and gennakers. The invention also relates to a method for manufacturing this fabric.

[0002] A spinnaker, after inflation by the wind, must have a very precise aerodynamic shape. The use of a stiff fabric is therefore preferred to facilitate inflation and maintain the ideal shape. The counterpart of the stiffness of the fabric is the production of fabrics prone to tearing under high stress, causing the spinnaker to burst. Traditionally, the use of fabrics with a textile base of Polyamide 6.6 is preferred, the high elasticity and tenacity of polyamide 6.6 allowing shock absorption. But this polyamide has disadvantages. Polyamide 6.6 is a hydrophilic polymer which gives the fiber a propensity to absorb water. A spinnaker made from a polyamide 6.6 fabric then tends to become heavier and age prematurely under the combined action of UV and hydrolysis.Polyester fabrics, on the other hand, being less sensitive to water absorption, have proven in practice to be too stiff to be used on sails such as spinnakers. The use of high-tenacity polyester fibres, preferably polyethylene terephthalate, which are supposed to provide even better resistance to tearing, has not led to their use in spinnaker use, as the great stiffness of the sails thus produced makes them prone to breakage and bursting under high stress.

[0003] Another drawback of spinnaker fabrics is their unsuitability for long-lasting decoration after the sail has been made, particularly using modern printing techniques.

[0004] Document WO 2011 / 042653 A1 discloses a lightweight fabric, in particular for a flying sail, for example a paraglider, formed from continuous warp and weft threads, the fabric being coated on one or both sides with a polyurethane. The bare fabric has a coverage rate TC of 1.8 to 4, preferably 2.6 to 3.2. The polyurethane is polyether or polycarbonate based having a modulus at 100% elongation of less than or equal to 5 MPa. The take-up rate is greater than or equal to 10% by weight, preferably 12 to 30% by weight, more preferably 15 to 25% by weight. The fabric has a weight, including coating, of 25 to 40 g / m 2 < .

[0005] The objective of the present invention is to overcome the drawbacks of the prior art, by proposing a fabric formed from polyester fibers which has a tear resistance, a modulus and an elasticity allowing its use in the production and use of light headsails of sailing boats and other surface vessels, such as spinnakers, asymmetric spinnakers, and gennakers.

[0006] Another objective of the invention is to provide such a fabric having lower water absorption, and exhibiting better resistance to hydrolysis, than existing solutions based on polyamide fabric.

[0007] Another objective of the invention is to provide a fabric which has high thermal stability and which allows the fabric to be printed by sublimation.

[0008] Still other objectives will appear upon reading the description of the invention.

[0009] These and other objectives are achieved by a fabric formed from continuous warp and weft yarns of high tenacity polyester, the fabric being as described in claim 1. The fabric is coated on one or both sides with a crosslinked polyurethane (PU). The crosslinked PU has the ability to compensate for the excessive stiffness (the very high modulus) and low elasticity of fabrics made from high tenacity polyester fibers. The crosslinked polyurethane is flexible and is therefore durable in the face of the mechanical stresses that the sail undergoes during its life. The polyurethane is a polyether, polyester or polycarbonate-based PU. The preferred polyurethane is a polycarbonate-based PU. The PU is obtained from a single-component polyurethane elastomer. This elastomer is formed from the polyol segments (polyether, polyester or polycarbonate), the isocyanate segments, and a chain extender or a hydroxylated crosslinking agent, as is known per se.The elastomer has a modulus at 100% elongation of between 6 and 15 MPa, more particularly between 6 and 10 MPa, typically between 6 and 9.5 MPa, for example approximately 8 MPa, according to DIN 53504. The elastomer is mixed with a crosslinker (not to be confused with the crosslinking agent used to form the elastomer), and the proportion of dry crosslinker relative to the dry elastomer is between 20% and 75%, better still between 30% and 75% by weight, in particular between 40 and 75% by weight, in particular between 50 and 75% by weight (for example approximately 67%). The crosslinker comprises in particular an isocyanate, melamine, or a mixture of isocyanate and melamine. This crosslinker makes it possible in particular to block all or part of the reactive functions (notably NCO and alcohol) remaining on the elastomer, to create additional bonds or crosslinks, and to obtain the crosslinked PU forming the coating of the fabric.The fabric according to the invention is intended for, or capable of forming, headsails of sailing boats and other surface vessels, such as spinnakers, asymmetric spinnakers, and gennakers.

[0010] The invention relates in particular to a fabric for light nautical sails of sailing boats and other surface vessels, such as spinnakers, asymmetric spinnakers, and gennakers, the fabric being formed from continuous polyester warp and weft threads and being coated on one or both sides with a crosslinked polymer, where: the polyester is polyethylene terephthalate (PET); the fabric has a density of between 20 and 50 threads / cm, preferably between 25 and 50 threads / cm, in warp and weft; the polymer is a crosslinked polyurethane (PU) based on polyether, polyester or polycarbonate, preferably polycarbonate; the PU is obtained by crosslinking (1) a single-component polyurethane elastomer having a modulus at 100% elongation of between 6 and 15 MPa, typically between 6 and 10 MPa, for example between 6 and 9.5 MPa, for example approximately 8 MPa according to standard DIN 53504, implemented in organic solvent phase (in particular dissolved in a solvent), (2) by a crosslinker, at a rate of a proportion of dry crosslinker relative to the dry elastomer of between 20 and 75% by weight, better still between 30% and 75% by weight, in particular between 40 and 75% by weight, in particular between 50 and 75% by weight.

[0011] Advantageously, the coated fabric has an elongation in the bias under 20 Lbs (9.07 Kg), between 10 and 30 100ths of an inch (2.54 and 7.62 mm), preferably between 14 and 25 100ths of an inch (3.56 and 6.25 mm), according to the NF EN ISO 13934-1 standard. The combination of the modulus at 100% elongation of the PU and the crosslinker rate, each taken in the given intervals, makes it possible in particular to obtain this elongation in the bias making it possible to provide the flexibility to the fabric which is necessary for the application and which the intrinsic tenacity of the PET yarn did not suggest. In particular, it will be possible to favor the high range of modulus values ​​over the low range of crosslinker rate values, and vice versa.

[0012] The dry coating rate relative to the total dry fabric may be in particular greater than 5%, in particular between 5% and 30% by weight, in particular between 10 and 30% by weight, better still between 15 and 25% by weight. The dry coating rate is the ratio by weight of dry coating (crosslinked PU) on the coated fabric, it is representative of the weight of dried / crosslinked coating present on the final fabric. The dry coating rate mentioned here means the total coating rate, either on one side or on two sides, depending on the case chosen.

[0013] The polyester is poly(ethylene terephthalate) or PET. PET consists of repeating units of ethylene terephthalate; however, within the scope of the invention are variants comprising a minor amount of other units, for example less than 10 mol%, especially less than 5 mol% of other units, per molecular chain of the polyester (comonomers to form these other units include, for example, isophthalic acid, naphthalene dicarboxylic acids, adipic acid, hydroxybenzoic acids, diethylene glycol, propylene glycol, trimellitic acid and pentaerythritol).

[0014] The polyester yarns are multifilament. They are formed from multiple continuous filaments. According to one embodiment, the fabric comprises warp yarns and weft yarns which have a dtex of between 11 and 235 dtex, for example between 22 and 110 dtex, in particular between 22 and 78 dtex, with in particular a DPF (decitex per filament) of between 1 and 4, preferably between 1.3 and 3.5.

[0015] The tenacity of PET yarns is greater than or equal to 6 cN / dtex, in particular between 6 and 7 cN / dtex. Their elongation at break is in particular greater than or equal to 20%, in particular between 20 and 30%. Tenacity and elongation at break are measured according to DIN EN ISO 2062.

[0016] PET fibers or yarns with these characteristics are commercially available and / or can be custom produced.

[0017] Polyester fibers may contain one or more additives, for example a stabilizing agent and / or an antistatic agent.

[0018] The bare fabric has a density of between 20 and 50 threads / cm, preferably between 25 and 50 threads / cm, in weft and a density of between 20 and 50 threads / cm, preferably between 25 and 50 threads / cm in warp. Preferably, the thread density is identical in warp and weft. Alternatively, the density in warp and weft may be different, in particular with a variation of between 10 and 30% between warp and weft, the density being higher in warp or weft, preferably in warp.

[0019] In one embodiment, the fabric has a hybrid construction, with the use of fibers or yarns of different counts between the warp and the weft. The fabric may then comprise warp yarns and weft yarns which have a dtex (count) of between 11 and 235 dtex, in particular between 22 and 110 dtex, in particular between 22 and 78 dtex, with the warp yarns having a count higher than the count of the weft yarns. In a non-preferred variant, it is the weft yarns which have a higher count. By higher, it may be understood in particular that the count of the yarns in one direction is higher by 1.5 or 2 to 5 times the count of the yarns in the other direction.

[0020] The weight of the coated fabric may be in particular between 25 and 130 g / m 2< , preferably between 30 and 120 g / m 2< .

[0021] The fabric of the present invention is characterized by a stiffness in the bias. The bias is said to be warp direction because it is measured in the direction at 45° relative to the warp threads. This stiffness in the bias is expressed by the elongation in 100ths of an inch (0.254 mm), which is measured under a force of 20 pounds (Lbs, or 89N) applied in the bias. This elongation characterizes the stiffness of the fabric in the bias. The standard used is NF EN ISO 13934-1: test pieces are produced with a width of 76.2 mm and a length of 300 mm. The jaws of the dynamometer are spaced 152.4 mm apart from each other and the measurement is carried out at a speed of 50 mm / min. In the bias, the test pieces are cut from the fabric according to these dimensions, applying an angle of 45° to the warp direction of the fabric, then the two pieces of fabric are superimposed and subjected together to the effect of the dynamometer.The elongation in 100ths of an inch in both the warp and weft directions is achieved according to the same standard, and in this case a single piece of fabric is used.

[0022] The elongation in the bias of the coated fabric under 20 Lbs (9.07 Kg), can in particular be between 10 and 30 100 ths of an inch (2.54 and 7.62 mm), preferably between 14 and 25 100 ths of an inch (3.56 mm and 6.25 mm). This is the preferred target that the invention sets itself. The flexible polyurethane coating makes it possible to achieve this objective, despite the fact that PET yarns with a high Young's modulus, generally between 3 and 15 GPa, give the fabric high stiffness and low elasticity. A coated fabric with a bias elongation of less than 10 100 ths of an inch (2.54 mm) will be too stiff and would risk bursting under high stress. A fabric with a bias stretch greater than 30 100ths of an inch (7.62 mm) will be too flexible and will result in a sail, such as a spinnaker, with degraded aerodynamic performance.

[0023] Young's modulus or elastic modulus characterizing polyester or PET fibers or yarns is the constant in pascals that links the stress and the deformation generated by this stress when we are in the elastic domain of the material. It is obtained by measuring the slope at the origin of the force=f(deformation) curve. The elongation at break is (L-L0) / L0*100, L being the length at break and L0 the initial length of the sample.

[0024] The modulus at 100% elongation as used to characterize the elastomer is no longer Young's modulus but an equivalent measured at 100% elongation.

[0025] The fabric of the present invention is obtained by solvent-borne polyurethane coating. The coating may have any of the characteristics mentioned below. Firstly, the fabric may be coated on one or both sides, preferably it is coated on one side.

[0026] A polyurethane comprises a stiff part (isocyanate) and a flexible part (polyol). A person skilled in the art knows how to find the compromise between the isocyanate / polyol ratio and the nature of the components to obtain the elastomer of desired stiffness, characterized by the modulus at 100% elongation. Preferably, the elastomer used in the coating is single-component, the isocyanate having reacted with the polyol, then with the chain extender or crosslinking agent, forming an elastomer generally still containing reactive functions such as NCO and alcohol. A person skilled in the art may refer to the literature on the production of copolymers or elastomers obtained from isocyanate, polyol and chain extenders or crosslinking agent, in particular the Thesis on Polymer and Composite Materials by Ségolène Hibon, INSA Lyon, France, 2006.

[0027] The coating composition is supplemented with a crosslinker, in particular an isocyanate or a melamine, or a mixture of the two. The term "isocyanate" means both an isocyanate and a polyisocyanate, alone or in a mixture with one or more other isocyanates and / or polyisocyanates. Unless otherwise indicated, the term "isocyanate" is to be understood herein as including the terms "isocyanate" and "polyisocyanate". Polyisocyanates are preferred. As regards melamine, this may in particular be melamine itself (1,3,5-triazine-2,4,6-triamine) or a compound or resin containing melamine, for example a melamine-formaldehyde resin.

[0028] The proportion of dry crosslinker relative to the dry elastomer is between 20 and 75% by weight, better between 30% and 75% by weight, in particular between 40 and 75% by weight, in particular between 50 and 75% by weight.

[0029] According to one embodiment, the polyurethane (and the starting elastomer) is polyether-based. In particular, the polyether-based polyurethane is linear or branched and comprises a polyether-type polyol part and an isocyanate part.

[0030] According to one embodiment, the polyurethane (and the starting elastomer) is polyester-based. In particular, the polyester-based polyurethane is linear or branched and comprises a polyester-type polyol part and an isocyanate part.

[0031] According to another embodiment, the polyurethane (and the starting elastomer) is polycarbonate-based. In particular, the polycarbonate-based polyurethane is linear or branched and comprises a polycarbonate-type polyol part and an isocyanate part. A polycarbonate-based polyurethane is used in the examples and constitutes a particularly suitable embodiment.

[0032] As for the elastomer and the crosslinker, the isocyanate part is preferably aliphatic, in fact aromatic isocyanates have the disadvantage of yellowing over time, which makes them less preferred, even if they are usable.

[0033] In one embodiment, the lightweight fabric of the present invention is obtained by solvent-borne polyurethane coating. This method of producing a coated fabric from the polyester fabric is another object of the invention. The coating may have any of the characteristics mentioned below.

[0034] The coating step is carried out using techniques conventionally used in textile coating, such as direct coating. "Direct coating" means coating by direct application, for example using a doctor blade, a cylinder, an air knife, a scarf, a Meyer bar (or the Champion process).

[0035] A PU elastomer or a crosslinked PU coating as defined herein is used for coating a high tenacity PET fabric as defined herein. This coating is intended in particular to give it the property(ies) described herein, in particular an elongation in the bias as described herein. The coating also provides a porosity suitable for the use for which the fabric is intended. This use can be translated by the manufacturing method which follows and which is another object of the invention.

[0036] The method of manufacturing the coated fabric of the invention comprises the following steps: a poly(ethylene terephthalate) (PET) fabric having a density of between 20 and 50 threads / cm, preferably between 25 and 50 threads / cm, in warp and weft is provided; one or two faces of this fabric are coated using a mixture of single-component polyurethane elastomer having a 100% elongation modulus as described above, solvent for the elastomer and a crosslinker, at a rate of a proportion of dry crosslinker relative to the dry elastomer as described above; the fabric is heated until the coating dries and crosslinks, a coated fabric is obtained; optionally, the fabric is printed, for example by sublimation, on one or both of its faces.

[0037] This process aims to manufacture a fabric as described above and consequently, the characteristics of the elements entering into the composition of the fabric and its coating are applicable to the process, to the choice of these elements for their implementation in the process, without it being necessary to repeat them in the following.

[0038] In particular, the drying and crosslinking step first comprises drying, for example at a temperature of between about 90 and about 120°C, then crosslinking at a temperature of between about 140 and about 210°C.

[0039] In one embodiment, the method comprises, after the drying and crosslinking step, one or more post-treatment steps giving the fabric anti-fouling and / or water-repellent properties. The term "anti-fouling" treatment means a treatment using antistatic and / or anti-tack products. The term "water-repellent" treatment means a treatment using fluorinated resins with or without a crosslinker for the fluorinated resin, for example an isocyanate. The water-repellent treatment is followed by a drying / crosslinking step. In one embodiment, the post-treatment is applied by any method known to those skilled in the art, in particular by padding, coating, spraying or plasma treatment. A treatment with silicone can also be carried out to improve the slipperiness of the fabric.

[0040] According to one embodiment, before coating, the fabric is calendered. Calendering crushes the fabric and spreads out the threads and filaments, which helps to close the pores of the fabric and reduce its porosity. According to one embodiment, calendering is carried out between a calendering tool, cylinder or roller and a counter-plate. The face of the fabric that undergoes the passage of the calendering tool, called the "calendering face", is smoothed relative to the other face.

[0041] According to one method, the coating is carried out on this calendering face. The adhesion of the polymer can be improved by first applying a primer treatment to this smooth face. This can be a physical treatment or a chemical treatment called an adhesion treatment. For example, this is a chemical treatment providing functional groups capable of reacting with groups in the polymer to form chemical bonds.

[0042] Alternatively, the coating is carried out on the other, unsmoothed side. It is understood that the dry coating rate varies depending on the side concerned, this rate being higher on the unsmoothed side, which allows the person skilled in the art to vary the quantity and weight of the coating. It is also possible to coat both sides.

[0043] In another embodiment, the fabric is calendered between two tools, cylinders or calendering rollers. Both sides of the fabric are smoothed. One or both sides are then coated, with or without a bonding treatment as described above.

[0044] The calendering is preferably carried out at a temperature of between about 150 and about 250°C, preferably between about 180 and about 210°C. The calendering is preferably carried out with a pressure of between about 150 and about 250 kg, preferably between about 180 and about 230 kg. The rotation speed of the calender may be between about 1 and about 30 m / min, preferably between about 10 and about 20 m / min.

[0045] The fabric of the present invention is obtained by coating polyurethane dissolved in a solvent. In particular, the coating contains the single-component elastomer (formed in particular from the isocyanate, the polyol and the chain extender or the crosslinking agent), in solution in the solvent. The film forms naturally during evaporation of the solvent. The solvent is an organic solvent and may in particular be chosen from the group consisting of aromatic solvents, alcohols, ketones, esters, dimethylformamide and n-methylpyrrolidone. In a particular embodiment, the solvent is selected from the group consisting of toluene, xylene, isopropanol, butanol, 1-methoxypropan-2-ol, methyl ethyl ketone, acetone, butanone, ethyl acetate, dimethylformamide, n-methylpyrolidone, and a mixture of at least two of them. For example, a mixture of toluene and isopropanol.

[0046] In one embodiment, the solvent-based polyurethane may be characterized by its concentration of between 20 and 50% by weight of uncrosslinked PU, in particular single-component elastomer, relative to the PU and solvent mixture. In one embodiment, this solvent-based polyurethane, in particular the elastomer in solution in the solvent, may be characterized by a viscosity of less than 100,000 mPa.s at 23°C, preferably between 5,000 and 60,000 mPa.s at 23°C (DIN EN ISO / A3 standard).

[0047] Therefore, in one embodiment, the lightweight fabric of the present invention is obtained or obtainable by coating polyurethane, preferably a single-component elastomer, in solvent phase.

[0048] The fabric coating composition of the present invention may further comprise additives. Said additives may be any additive commonly used in fabric coating compositions. They are in particular chosen from the group consisting of viscosity modifiers, UV stabilizers, dyes, dispersants, surfactants. According to one embodiment, the coating comprises an anti-UV agent.

[0049] The coated fabrics described here prove capable of being printed by the so-called sublimation technique. According to one aspect of the invention, this coated fabric is colored, printed or decorated by a sublimation technique. This can in particular be implemented by printing a pattern on a support (transfer support) with one or more dyes that can be sublimated at high temperature. The support is then applied in contact with the coated fabric, then heat calendered, for example at approximately 200°C and under pressure. The dyes pass into the gas phase and are transferred into the coating, and / or to the surface and / or into the fiber. The PET polyester remains stable at this temperature.

[0050] Spinnakers (standard or asymmetrical) and gennakers are windward inflatable sails, which generally comprise three angular peaks, commonly called the head or halyard point, the clew point and the tack point. These sails are obtained by assembling strips, in particular several radial strips which spread out from each angular peak, each radial strip being previously obtained in the form of a flat piece of fabric, cut according to the geometric needs of the strip to be obtained.

[0051] The invention thus relates to an article such as a headsail for a sailboat and other surface vessels, such as a spinnaker, asymmetric spinnaker, and gennaker, comprising a fabric coated according to the invention or made from one or more fabrics or widths of fabric coated according to the invention. In particular, the article may comprise several fabrics or widths according to the invention, assembled to form the article in question. In one embodiment, the nautical sail bears a pattern printed by sublimation. In particular, the nautical sail bears a pattern formed from dye inside the PU coating and / or on the surface or inside the PET threads.

[0052] The invention also relates to said strips cut from a fabric according to the invention.

[0053] The invention will now be described with the aid of examples corresponding to the preferred embodiments, these being given by way of illustration without being limiting. Example:

[0054] Example 1 :This example compares the impact of a polyurethane coating on conventional PU-coated polyamide 6.6 fabrics (Control) and high-tenacity polyethylene terephthalate (PET) fabrics coated on one side with a PU according to the invention.

[0055] PA6.6 is a classic polyamide fabric in the spinnaker field, with a PU coating obtained from PU elastomer having a 100% elongation modulus of 32.4 and melamine formaldehyde crosslinker. The proportion of dry crosslinker to dry elastomer is 104%. The PU is implemented in a 50 / 50 mixture of toluene and isopropanol.

[0056] The PET has a PU coating obtained from PU elastomer with a 100% elongation modulus of 8 and melamine formaldehyde crosslinker. The proportion of dry crosslinker to dry elastomer is 66.9%. The PU is implemented in a 50 / 50 mixture of toluene and isopropanol.

[0057] The toughness of PET is 6.8 cN / dtex. The elongation at break is 24.6%.

[0058] The coating is carried out using a doctor blade, and is followed by a drying step at 100°C, then a crosslinking step at 170°C). The speed is 27 m / min. [Table 1] Witness Invention - example 1 Nature thread PA6.6 PET Title (dtex) 33 33 DPF 3,3 2,1 Number of warp threads x weft threads 44x45 44x44,5 PU modulus at 100% elongation (MPa) - DIN 53504 standard 32,4 8 % crosslinker (dry weight) 104 66,9 Weight (g / m 2 < ) - ISO2286-2 41,2 38,4 Bias elongation under 20 lbs (in 100ths of an inch) 10,9 20,1 Chain elongation under 20 lbs (in 100ths of an inch) 13,7 10,6 Weft elongation under 20 lbs (in 100ths of an inch) 16,8 5,7 Breaking strength ch (daN / 5cm) - NF EN ISO 13934-1 42,6 38,5 Breaking strength tr (daN / 5cm) - NF EN ISO 13934-1 41,5 44,4 Tear resistance ch (Lbs) - NF EN ISO 13937-2 5,7 5,3 Tear resistance tr (Lbs) - NF EN ISO 13937-2 4,9 5,4 Water absorption when new (%) 0,3 0,02 Water absorption after aging (%) 1,1 0,1 [Table 2] Witness Invention - example 2 Nature thread PA6.6 PET Title (dtex) 50 44 DPF 3,8 3.2 Number of warp threads x weft threads 42x42 39,3x39 PU modulus at 100% elongation (MPa) - DIN 53504 standard 32,4 8 % crosslinker (dry weight) 104 66,9 Weight (g / m 2 < ) - ISO2286-2 55.0 47.0 Bias elongation under 20 lbs (in 100ths of an inch) 9,3 16,1 Chain elongation under 20 lbs (in 100ths of an inch) 9,8 9,3 Weft elongation under 20 lbs (in 100ths of an inch) 13,3 7,9 Breaking strength ch (daN / 5cm) - NF EN ISO 13934-1 63,2 50,9 Breaking strength tr (daN / 5cm) - NF EN ISO 13934-1 58,6 48,9 Tear resistance ch (Lbs) - NF EN ISO 13937-2 7,4 14,1 Tear resistance tr (Lbs) - NF EN ISO 13937-2 5,6 12,8 Example 2:

[0059] The fabric of the invention of example 1 in 33 dtex yarns is taken and compared with counter-examples 1 and 2, which differ by combinations of PU modulus and crosslinker content which are outside the limits of the invention. [Table 3] Invention example 1 Counterexample 1 Counterexample 2 Nature thread PET PET PET Title (dtex) 33 33 33 DPF 2,1 2,1 2,1 Number of warp threads x weft threads 44x44,5 44x44,5 44x44,5 PU modulus at 100% elongation (MPa) - DIN 53504 standard 8 2 8 % crosslinker (dry weight) 66,9 15.4 16.5 Weight (g / m 2 < ) - ISO2286-2 38,4 38.6 38.5 Bias elongation under 20 lbs (in 100ths of an inch) 20,1 53.8 47.4 Chain elongation under 20 lbs (in 100ths of an inch) 10,6 8.8 10.4 Weft elongation under 20 lbs (in 100ths of an inch) 5,7 6.6 6.3 Breaking strength ch (daN / 5cm) - NF EN ISO 13934-1 38,5 39.4 39.7 Breaking strength tr (daN / 5cm) - NF EN ISO 13934-1 44,4 40.4 43.3 Tear resistance ch (Lbs) - NF EN ISO 13937-2 5,3 9.7 7.5 Tear resistance tr (Lbs) - NF EN ISO 13937-2 5,4 9.5 8.0 Water absorption when new (%) 0,02 0.4 0.1 Water absorption after aging (%) 0,1 0.9 0.2

[0060] Methods and measures used in the application (characteristics of the invention and examples): NF EN ISO 2062 - Determination of breaking force and elongation at break of individual yarns using a constant rate of elongation test apparatus, using Method A of the standard. Breaking force (unit centiNewton - cN): maximum force developed to break the sample during a tensile test conducted up to breakage Elongation at break (%): increase in the length of the sample measured at breakage of the latter 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).

[0061] The test measures the strength and elongation at break of the sample, characteristic quantities of the wire.

[0062] The wire is placed between two clamps, 500 mm apart. The device (Dynamometer) then moves the clamps away from each other at a constant speed of 500 mm / min and continuously measures the applied force. The force required to break the wire is measured as well as the increase in length of the wire upon breaking.

[0063] Mean breaking force and mean elongation at break are the two data characterized by this test. Toughness is calculated from the breaking force related to the linear mass.

[0064] The modulus at 100% elongation of the single-component polyurethane elastomer is measured according to DIN 53504. The modulus is defined in 3.4 of the "Spannungswerte" standard. The measurement is carried out on dumbbell-shaped specimens (Schulterstab) of type S2, however, with a bar length IS of 55 mm and a thickness of 200 µm. The equipment used is a dynamometer. The dumbbell specimen is placed in the clamps, spaced apart by a length L 0 with the minimum possible pre-tension. The clamps are then moved apart at a constant speed of 400 mm / min and the dynamometer measures the applied force as a function of the elongation. The modulus or stress at 100% elongation in MPa is the ratio of force measured at 100% elongation to the initial cross-section of the specimen. This is described in paragraph 9.4 Spannungswerte of DIN 53504.

[0065] The fabric elongations are measured according to the NF EN ISO 13934-1 standard, as described in the general description. The lower elongation in the direction of the warp and weft yarns due to the polyester nature is compensated by a higher elongation in the bias (measured here in the warp direction). This elongation in the bias compensates for the excessive rigidity of PET and avoids the risk of breakage and bursting under high stresses. The mechanical performances are equivalent or even superior, this translates into a polyester fabric suitable for spinnaker use.

[0066] The water absorption of the coated fabric in Example 1 was measured according to Tappi 441 om-90. One measurement was carried out on the new coated fabric, another after aging. It is expressed in %. The equipment consists of a square rubber support and a metal ring coated at its base with a rubber gasket. The sample is placed on the square support and the metal ring is placed on the sample. A clamping device makes the system watertight. A certain quantity of water (100 ml) is placed in the ring, in contact with the sample for a specific time (1 minute). When the time is up, the water is removed from the cylindrical ring, the water residue remaining on the surface of the sample is removed using a cylinder as described in the standard, by moving this cylinder back and forth over the sample placed between two blotters, without applying pressure.The percentage of water absorbed is calculated by the difference in weight before and after contact with water.

[0067] For aging, the fabric is placed for 4 hours in a pressure cooker with salt water (30 g / l) at operating temperature and pressure. A 1-hour treatment is then applied by floating the fabric attached to a mill-type assembly (4-blade assembly, with the fabric attached to the end of one of the blades) in the open air at high speed.

[0068] The fabric according to the invention saw its water absorption change almost unchanged after aging. This level of resistance to water absorption is another surprising result.

[0069] The test measures the strength and elongation at break of the sample, characteristic quantities of the wire.

[0070] The wire is placed between two clamps, 500 mm apart. The device (Dynamometer) then moves the clamps away from each other at a constant speed of 500 mm / min and continuously measures the applied force. The force required to break the wire is measured as well as the increase in length of the wire at break. Mean breaking force and mean elongation at break are the two data characterized by this test. Toughness is calculated from the breaking force related to the linear mass.

[0071] The modulus at 100% elongation of the single-component polyurethane elastomer is measured according to DIN 53504. The modulus is defined in 3.4 of the "Spannungswerte" standard. The measurement is carried out on dumbbell-shaped specimens (Schulterstab) of type S2, however, with a bar length IS of 55 mm and a thickness of 200 µm. The equipment used is a dynamometer. The dumbbell specimen is placed in the clamps, spaced apart by a length L 0 with the minimum possible pre-tension. The clamps are then moved apart at a constant speed of 400 mm / min and the dynamometer measures the applied force as a function of the elongation. The modulus or stress at 100% elongation in MPa is the ratio of force measured at 100% elongation to the initial cross-section of the specimen. This is described in paragraph 9.4 Spannungswerte of DIN 53504.

[0072] The fabric elongations are measured according to the NF EN ISO 13934-1 standard, as described in the general description. The lower elongation in the direction of the warp and weft yarns due to the polyester nature is compensated by a higher elongation in the bias (measured here in the warp direction). This elongation in the bias compensates for the excessive rigidity of PET and avoids the risk of breakage and bursting under high stresses. The mechanical performances are equivalent or even superior, this translates into a polyester fabric suitable for spinnaker use.

[0073] The water absorption of the coated fabric in Example 1 was measured according to Tappi 441 om-90. One measurement was carried out on the new coated fabric, another after aging. It is expressed in %. The equipment consists of a square rubber support and a metal ring coated at its base with a rubber gasket. The sample is placed on the square support and the metal ring is placed on the sample. A clamping device makes the system watertight. A certain quantity of water (100 ml) is placed in the ring, in contact with the sample for a specific time (1 minute). When the time is up, the water is removed from the cylindrical ring, the water residue remaining on the surface of the sample is removed using a cylinder as described in the standard, by moving this cylinder back and forth over the sample placed between two blotters, without applying pressure.The percentage of water absorbed is calculated by the difference in weight before and after contact with water.

[0074] For aging, the fabric is placed for 4 hours in a pressure cooker with salt water (30 g / l) at operating temperature and pressure. A 1-hour treatment is then applied by floating the fabric attached to a mill-type assembly (4-blade assembly, with the fabric attached to the end of one of the blades) in the open air at high speed.

[0075] The fabric according to the invention saw its water absorption change almost unchanged after aging. This level of resistance to water absorption is another surprising result.

Claims

1. A fabric for light nautical sails of sailing ships and other surface vessels, such as spinnakers, asymmetric spinnakers, and gennakers, the fabric being formed of continuous polyester warp and weft yarns and being coated on one or both sides with a cross-linked polymer, wherein: the Polyester is made of polyethylene terephthalate (PET), the PET has a tenacity greater than or equal to 6 cN / dtex, in particular between 6 and 7 cN / dtex, the fabric has a density of between 20 and 50 threads / cm, preferably between 25 and 50 threads / cm, in both warp and weft, the polymer is a cross-linked polyurethane (PU) based on polyether, polyester or polycarbonate, and this PU is derived from cross-linking (1) of a single-component polyurethane elastomer having a modulus at 100% elongation of between 6 and 15 MPa, more particularly between 6 and 10 MPa, typically between 6 and 9.5 MPa, according to standard DIN 53504, used in the solvent phase, (2) with a crosslinker, in a proportion of dry crosslinker to dry elastomer of between 20% and 75% by weight, in particular between 30% and 75% by weight, in particular between approximately 50% and approximately 75% by weight.

2. Fabric according to claim 1, characterized in that the coated fabric has a bias elongation under a load of 20 Lbs (9.07 Kg) of between 10 and 30 100ths of an inch (2.54 and 7.62 mm), preferably between 14 and 25 100ths of an inch (6.56 and 6.25 mm), measured on specimens 76.2 mm wide and 300 mm long in accordance with standard NF EN ISO 13934-1.

3. Fabric according to claim 1 or 2, characterised in that the fabric comprises warp threads and weft threads which have a titre of between 11 and 235 dtex, in particular between 22 and 110 dtex, more particularly between 22 and 78 dtex, with a DPF (decitex per filament) of between 1 and 4, preferably 1.3 and 3.5.

4. Fabric according to any one of the preceding claims, characterised in that the PET has an elongation at break greater than or equal to 20%, in particular between 20 and 30%, according to the DIN EN ISO 2062 standard.

5. Fabric according to any one of the preceding claims, characterised in that the ratio of dry coating of crosslinked PU to the total dry fabric is greater than 5% by weight, in particular between 5 and 30% by weight, preferably between 10 and 30% by weight, in more preferably between 15 and 25% by weight.

6. Fabric according to any one of the preceding claims, characterised in that the weight of the coated fabric is between 25 and 130 g / m2preferably between 30 and 120 g / m2.

7. Fabric according to any one of the preceding claims, characterized in that the crosslinker of the elastomer is an isocyanate, a polyisocyanate, melamine, a compound comprising melamine, or a mixture of isocyanate and melamine.

8. Fabric according to any one of the preceding claims, characterised in that the isocyanates or polyisocyanates and / or the crosslinker are aliphatic.

9. Light nautical sail, in particular spinnaker, asymmetric spinnaker, or gennaker, comprising a fabric according to any one of claims 1 to 8, or formed from the assembly of several fabrics according to any one of claims 1 to 8.

10. Lightweight nautical sail as claimed in claim 9, characterised in that it bears a sublimation-printed motif.

11. A method of manufacturing the coated fabric according to any one of claims 1 to 8, comprising: - a polyethylene terephthalate (PET) fabric with a density of between 20 and 50 threads / cm, preferably between 25 and 50 threads / cm, in warp and weft, and the PET has a tenacity greater than or equal to 6 cN / dtex, in particular between 6 and 7 cN / dtex; - one or both sides of this fabric are coated with a mixture of a single-component polyurethane elastomer having a 100% elongation modulus of between 6 and 15 MPa, in particular between 6 and 10 MPa, typically between 6 and 9.5 MPa, according to standard DIN 53504; a solvent for the elastomer; and a crosslinker, in a proportion of dry crosslinker to dry elastomer of between approximately 20% and approximately 75% by weight, in particular between approximately 30% and approximately 75% by weight, and more specifically between approximately 50% and approximately 75% by weight; - the fabric is heated until the coating dries and cross-links, - a coated fabric is obtained; - optionally, the fabric is printed, for example by sublimation, on one or both sides.