Coated lightweight fabrics, especially for glider wings

Abstract

1. A fabric for glider wings, particularly paraglider wings, formed from continuous warp and weft yarns, one or both of whose two surfaces are coated with polyurethane (PU), characterized in that the uncoated fabric has a coverage factor (TC) in the range of 1.8 to 4, the yarns being made of poly(ethylene terephthalate) (PET), the fabric has a density in the range of 30 to 50 threads / cm with respect to the density of the warp and weft yarns, the polyurethane being a crosslinked polyurethane (PU) of the polyether or polycarbonate type, and the PU is derived from (1) crosslinking a single-component polyurethane (PU) used in an organic solvent phase in production and having a modulus of elasticity of less than 5 MPa at 100% elongation according to standard DIN 53504, with (2) a crosslinking agent based on a ratio of dry crosslinking agent to dry elastomer in the range of about 5% to about 30%.

Description

[Technical Field]

[0001] The present invention relates to a lightweight fabric for a paraglider-type glider wing and a fabric manufacturing method for producing the fabric. [Background technology]

[0002] In the field of gliders, such as paragliders, fabric manufacturers have long sought to combine lightness, low porosity, and durability. This represents a difficult equation to solve, since a reduction in porosity is usually synonymous with an increase in mass. In fact, porosity depends on the density of the fabric, i.e., the number of warp and weft threads per unit area. Fabric porosity also depends on the presence of a coating intended to more or less close the pores of the fabric. Coatings are in fact crucial and constitute a significant part of the mass of the coated fabric, and therefore of the glider wing. Coatings are also important for giving the fabric adequate toughness across the bias.

[0003] The coating is a key element necessary to provide the required porosity, and it must be durable. The concept of durability can encompass various criteria, such as UV stability and hydrolytic stability, and therefore more comprehensively, atmospheric stability, weathering stability, and water resistance stability. Hydrolytic stability should be considered as the main factor in maintaining porosity characteristics over time. Currently, wing blades, such as paraglider blades, are made of polyamide and use polyester- or polycarbonate-based polyurethanes (PU) as coating materials. These coatings have relatively good resistance to UV, but on the other hand, they have limited durability in terms of hydrolytic stability. The fabric mass is usually 20-40 g / m 2 The range is.

[0004] The properties of the warp and weft yarns also have an influence on the properties and durability of the wing. In practice, the wing is made of polyamide 6.6; however, polyamide 6.6 is a hydrophilic polymer, giving the fabric a tendency to absorb water. Paraglider wings made from polyamide 6.6-based fabrics therefore tend to become heavy and age prematurely under the combined action of UV radiation and hydrolysis. The absorbed water reduces the mechanical performance of the polyamide and of the coating.

[0005] Thus, techniques are already known for producing coated fabrics that exhibit adequate porosity when the coated fabric is new. However, in paragliding practice, known coated fabrics have been found to be subject to degradation of this nature in humid environments, presenting longevity problems for wings made from them. Summary of the Invention [Problem to be solved by the invention]

[0006] One of the objects of the present invention is to remedy those deficiencies and provide a coated fabric which combines both lightweight properties and good mechanical performance, as well as properties of porosity, less susceptibility or even insensitivity to water absorption, and durability, which may have practical application for use in safe and durable glider wings, particularly paraglider wings.

[0007] Another object of the invention is to provide such a fabric which retains the best mechanical properties necessary for a high standard of paraglider wing, in particular with adequate toughness along the bias and high tear resistance.

[0008] Another object is to have the ability to print fabrics by sublimation printing and thus to be able to provide novel coated fabrics suitable for being printed in this manner.

[0009] Still other objects will become apparent upon reading the following description of the invention. [Means for solving the problem]

[0010] These and other objects are achieved by a lightweight fabric formed from continuous warp and weft yarns made of poly(ethylene terephthalate) (PET) and coated on one or both of its two surfaces, preferably only on the sole surface, with polyurethane (PU). The fabric preferably has a warp and weft density ranging from 30 to 50 threads / cm. The polyurethane is advantageously a crosslinked polyurethane (PU), which may be polyether, polyester, or polycarbonate-based. According to another preferred characteristic feature, the PU is obtained from a single-component polyurethane elastomer, which is formed, as known per se, from polyol segments (polyether, polyester, or polycarbonate), isocyanate segments, and a chain extender or hydroxylated crosslinker. One important preferred characteristic is that the elastomer has a modulus at 100% elongation according to DIN 53504 of about 5 MPa or less, particularly in the range of 1 to 4 MPa, and particularly in the range of 1 to 3 MPa, for example about 2 MPa. Another important preferred characteristic is that the elastomer is a mixture with a crosslinking agent (not to be confused with the crosslinking agent used to form the elastomer). In particular, the ratio of dry crosslinking agent to dry elastomer is in the range of about 5% to about 30% by weight, particularly in the range of about 7% to about 20% by weight, and particularly in the range of about 8% to about 18% by weight (e.g., about 8% to about 16% by weight). The crosslinking agent particularly includes isocyanates, melamines, or mixtures of isocyanates and melamines. The crosslinking agent particularly blocks all or part of the reactive functional groups (e.g., NCO and alcohol) remaining in the elastomer, allowing further bonds or crosslinks to form and obtain a crosslinked PU that forms a coating for the fabric. The fabric according to the invention is designed for or is suitable for forming a glider wing, in particular a paraglider wing. DETAILED DESCRIPTION OF THE INVENTION

[0011] The fabric advantageously has a coverage factor TC in the range of 1.8 to 4, in particular in the range of 2.6 to 3.2. This TC (coverage factor) is the coverage factor of the resulting PET fabric derived from the weaving operation and before any possible calendering or similar operation. This TC is calculated as follows: TC = ((number of threads / cm) x (diameter of one thread in cm)) (warp) + ((number of threads / cm) x (diameter of one thread in cm)) (weft). The TC value maintained in the present invention corresponds to a value that, on the one hand, limits the rate of absorption of the coating material in order to obtain a low porosity appropriate for the field of use of the fabric, and, as a result, makes it possible, on the other hand, to limit the final mass of the coated fabric, and, finally and advantageously, provides the fabric with a well-closed structure, possibly reinforced by the calendering process afterwards.

[0012] The invention relates in particular to a fabric for glider wings, in particular paraglider wings, formed from continuous warp and weft threads and coated on one or both of its two surfaces with polyurethane (PU), the uncoated fabric having a coverage factor TC in the range of 1.8 to 4, the threads being made of poly(ethylene terephthalate) (PET), the fabric having a warp and weft density in the range of 30 to 50 threads / cm, the polyurethane being a crosslinked polyurethane of polyether, polyester or polycarbonate type. The polyurethane (PU) is characterized in that it is derived from (1) a single-component polyurethane elastomer, which has a modulus at 100% elongation of less than 5 MPa, in particular in the range of 1 to 4 MPa, in particular in the range of 1 to 3 MPa, according to the standard DIN 53504, and is used in an organic solvent phase (in particular dissolved in a solvent) in the implementation, and (2) a crosslinking agent, based on a ratio of dry crosslinking agent to dry elastomer in the range of about 5% to about 30% by weight, in particular in the range of about 7% to about 20% by weight, in particular in the range of about 8% to about 18% by weight.

[0013] The fabrics according to the invention surprisingly have the ability to maintain their initial porosity (when new) or to experience only a slight increase in porosity over time, and therefore during the use of the fabric. At the same time, these fabrics also offer the advantage of experiencing only a low level of increase in water absorption over time or during their use. A way has been found that makes it possible to provide fabrics for glider wings, in particular paraglider wings, that have excellent properties with respect to porosity, less susceptibility to water absorption, or indeed no susceptibility, over time and use, thereby making it possible to substantially maintain the properties of lightness and good mechanical performance that allow the wing to be used efficiently and safely.

[0014] This fabric has a weight of 25 to 42 g / m, including the coating. 2 , especially 27-40g / m 2 The mass can range from 0.01 to 0.01.

[0015] According to one embodiment, the dry absorbency of the coating material is 10% by weight or more, in particular in the range of 10% to 30% by weight, preferably in the range of 12% to 30% by weight, more preferably in the range of 15% to 25% by weight. The dry absorbency is the ratio of the weight of the dry coating (in particular the crosslinked PU) on the coated fabric and represents the weight of the dry / crosslinked coating finally present on the fabric.

[0016] PET is made up of repeating units of ethylene terephthalate; however, the scope of the present invention actually extends to variants that also contain small amounts of other units, e.g., less than 10 mol %, particularly less than 5 mol %, per polyester molecular chain (comonomers for forming these other units include, for example, isophthalic acid, naphthalenedicarboxylic acid, adipic acid, hydroxybenzoic acid, diethylene glycol, propylene glycol, trimellitic acid, and pentaerythritol).

[0017] The polyester yarns are multifilament yarns. They are formed from multiple continuous fibers. According to one embodiment, the fabric comprises warp and weft yarns having a dtex of 11 to 14 dtex, for example 11 to 33 dtex, and in particular a DPF (decitex per fiber) of 1 to 4, preferably 1.3 to 3.5.

[0018] In one embodiment, the warp and weft yarns have the same count and have the same DPF.

[0019] In another embodiment, the warp and weft yarns have different counts, with the count of the yarns in one direction being strictly higher than the count of the yarns in the other direction. For example, the count of the yarns in one direction is in the range of 30-44 dtex, particularly in the range of 30-36 dtex, while the count of the yarns in the other direction is in the range of 11-33 dtex, particularly in the range of 19-26 dtex, with the count of the yarns in the first direction being strictly higher than the count of the yarns in the other direction. According to one embodiment, the higher count yarns are in the weft direction. In another embodiment, the higher count yarns are in the warp direction.

[0020] In other embodiments, it is possible to provide a variety of yarn counts in the same given direction in either the warp or weft, or in both the warp and weft directions, in which case there are at least two yarns in the warp direction and / or the weft direction with different yarn counts.

[0021] The tenacity (or tensile strength) of the PET yarns is in particular greater than 6 cN / dtex, in particular in the range of 6-7 cN / dtex. Their elongation at break is in particular greater than 20%, in particular in the range of 20% to 30%. Tenacity and elongation at break are measured according to the standard DIN EN ISO 2062.

[0022] PET fibers or yarns with these characteristic properties are commercially available and / or can be made to order.

[0023] The polyester yarn optionally contains one or more additives, such as stabilizers and / or antistatic agents.

[0024] In one embodiment, the fabrics of the present invention are characterized by tenacity across the bias. The bias is said to be in the warp direction if it is measured along a direction at 45° to the warp yarns. The bias is said to be in the weft direction if it is measured along a direction at 45° to the weft yarns. The stretch is measured as a percentage under a force of 3 pounds (1.36 kg) applied along the bias. This stretch characterizes the tenacity of the fabric across the bias. The standard used is NF EN ISO 13934-1, and test specimens are made having a width of 50 mm and a length of 300 mm.

[0025] The dynamometer clamps are spaced 200 mm apart and measurements are taken at a rate of 100 mm / min.

[0026] In particular, the coated fabric according to the invention has an elongation at 3 lbs, on the bias along the warp and weft directions, of 10% or less, the elongation therefore being in the range of 1% to 10%, preferably in the range of 3% to 10%, more preferably in the range of 5% to 10%.

[0027] According to one embodiment, the lightweight fabric is made according to standard NFG 07111 (100 cm 2 measured according to the measured surface area, under a pressure of 2000 Pa and 20 L / m 2 / min or less.

[0028] According to one embodiment, the PET fabric used in the implementation is a calendered fabric, which means that it has been calendered before being coated with PU. Calendering crushes the fabric and opens up the yarns and constituent fibers, which contributes to closing the pores of the fabric and reducing its porosity.

[0029] The fabric of the present invention is obtained by coating with polyurethane in a solvent phase. This coating can have any one of the characteristic properties mentioned below. First, the fabric can be coated on one or both of its two surfaces, preferably on one surface.

[0030] Polyurethanes contain a rigid portion (isocyanate) and a flexible portion (polyol). Those skilled in the art know how to find a compromise between the isocyanate / polyol ratio and the properties of the components to obtain an elastomer with the desired toughness, characterized by a modulus at 100% elongation. Preferably, the elastomers used in the coating are single-component elastomers, in which the isocyanate is reacted with a polyol and then with a chain extender or crosslinker to form an elastomer that usually still contains reactive functional groups, such as NCO and alcohols. Those skilled in the art can refer to the literature for the preparation of copolymers or elastomers obtained from isocyanates, polyols, and chain extenders or crosslinkers, in particular to *Thesis on Polymer Materials and Composites* by Segolene Hibon, Institut National de Sciences Appliquees-INSA (National Institute of Applied Sciences) in Lyon, France, 2006.

[0031] The coating composition is supplemented with a crosslinking agent, in particular an isocyanate or melamine, or a mixture of the two. The term "isocyanate" is understood to mean both isocyanates and polyisocyanates, either alone or as a mixture with one or more other isocyanates and / or polyisocyanates. The term "isocyanate" should be understood here to include the terms "isocyanate" and "polyisocyanate." Polyisocyanates are preferred. With regard to melamine, it can be, in particular, melamine itself (1,3,5-triazine-, 4,6-triamine) or a mixture or resin containing melamine, such as melamine-formaldehyde resin.

[0032] According to one embodiment, the ratio of dry crosslinker to dry elastomer is in the range of about 5% to about 30% by weight, particularly in the range of about 7% to about 20% by weight, and particularly in the range of about 8% to about 18% by weight.

[0033] According to one embodiment, the polyurethane (and starting elastomer) is polyether-based. In particular, the polyether-based polyurethane is linear or branched and contains polyol moieties and isocyanate moieties of the polyether type.

[0034] According to one embodiment, the polyurethane (and starting elastomer) is polyester-based. In particular, the polyester-based polyurethane is linear or branched and contains polyester-type polyol moieties and isocyanate moieties.

[0035] According to another embodiment, the polyurethane (and starting elastomer) is polycarbonate-based, in particular the polycarbonate-based polyurethane is linear or branched and contains polyol moieties of the polycarbonate type and isocyanate moieties.

[0036] For elastomers and crosslinkers, the isocyanate moiety is preferably aliphatic; indeed, aromatic isocyanates have the drawback of turning yellow over time, which makes them less preferred, although they can be used.

[0037] In one embodiment, the lightweight fabric of the present invention is obtained by coating polyurethane in a solvent phase. A fabric manufacturing method for producing a coated fabric from a polyester fabric is another object of the present invention. The coating can have any one of the characteristic properties mentioned below.

[0038] The coating step is carried out by techniques commonly used for coating textiles, such as direct coating. The term "direct coating" is understood to refer to direct deposition coating processes, for example using a doctor blade, cylinder, air knife, padder, or using a Mayer rod (or Champion process).

[0039] Another object of the present invention is the use of a PU elastomer or crosslinked PU coating as defined herein for coating a high tenacity PET fabric as defined herein, which coating is intended in particular to impart to the fabric the property or properties as defined herein, in particular bias stretch as described herein, and / or very low water absorption both new and after aging or use as described herein, and / or porosity that shows no or only a slight increase between the new coated fabric and the coated fabric after aging or use as described herein. This use can result in the following manufacturing method, which is another object of the present invention:

[0040] The fabric manufacturing method for producing the coated fabric includes, inter alia, the following steps: (a) A polyester fabric according to the present invention is provided, preferably the fabric is calendered. (b) One or both of the two surfaces of this fabric are coated using a solvent phase polyurethane according to the present invention, as described herein, preferably from a single component elastomer dissolved in a solvent and in a mixture with a crosslinker, at a coating rate according to the present invention. (c) The fabric is heated until the coating dries and crosslinks. (d) A coated fabric according to the present invention is obtained. (e) Optionally, the fabric is printed on one or both of its two surfaces, for example by sublimation printing.

[0041] The object of the present invention is to provide a method for producing a fabric, in particular a coated fabric, which method comprises the following features: A fabric is provided, the fabric being made from poly(ethylene terephthalate) (PET) having a warp and weft density in the range of 30-50 threads / cm. One or both of the two surfaces of the fabric is coated with a mixture of a single-component polyurethane elastomer having a modulus at 100% elongation of less than about 5 MPa, in particular in the range of 1-4 MPa, in particular 1-3 MPa, according to standard DIN 53504, a solvent for the elastomer, and a crosslinker, based on a ratio of dry crosslinker to dry elastomer in the range of about 5% to about 30% by weight, in particular in the range of about 7% to about 20% by weight, in particular in the range of about 8% to about 18% by weight. The fabric is heated until the coating dries and crosslinks. Coated fabric is obtained. Optionally, the fabric is printed on one or both of its two surfaces, for example by sublimation printing.

[0042] This method is intended to produce the fabric described above, and therefore the characteristic properties of the elements used in the production of this fabric are applicable to this method and to the selection of those elements for their use in this method, without the need to repeat them in the following sections.

[0043] The PET fabric may be advantageously calendered prior to coating.

[0044] According to one embodiment, the PET fabric is calendered between a tool, cylinder, or calender roll and a counterplate before coating. The surface of the fabric that has passed through the calender tool, referred to as the "calendered surface," is smoothed compared to other surfaces.

[0045] According to one embodiment, a coating is applied to the calendered surface. Adhesion of the polymer can be promoted by first applying a primer to the smooth surface. This can be a physical or chemical treatment, such as a chemical treatment that provides functional groups that can react with groups on the polymer to form chemical bonds.

[0046] According to another embodiment, the coating is applied to another surface that is not smoothed. It should be understood that the rate of uptake of the coating varies depending on the surface involved, this rate being higher on the non-smoothed surface, thereby allowing the skilled person to adjust the amount and mass of the coating. It is also possible to coat both surfaces.

[0047] According to another embodiment, the PET fabric is calendered between two calendering devices, cylinders, or calendering rolls before coating. Both surfaces of the fabric are smoothed. One or both of the two surfaces are then coated, with or without an adhesive treatment as described above.

[0048] The calendering of the PET fabric is preferably carried out at a temperature in the range of 150 to 250° C., preferably in the range of 180 to 210° C. The calendering is preferably carried out at a pressure in the range of 150 to 250 kg, preferably in the range of 180 to 230 kg. The rotation speed of the calender can be in the range of 1 to 30 m / min, preferably in the range of 1 to 20 m / min.

[0049] The lightweight fabrics of the present invention are obtained by coating with polyurethane in a solvent phase, which coating can have any one of the characteristic properties mentioned below.

[0050] The PU has a modulus at 100% elongation according to standard DIN 53504 of less than about 5 MPa, in particular in the range of 1 to 4 MPa, in particular in the range of 1 to 3 MPa. The PU is placed in solution in an organic solvent. The polymer is dissolved in the medium. A crosslinker for the PU is added to this solution. In particular, the ratio of dry crosslinker to dry polyurethane is in the range of about 5% to about 30% by weight, in particular in the range of about 7% to about 20% by weight, in particular in the range of about 8% to about 18% by weight.

[0051] The fabric of the present invention is obtained by coating with polyurethane dissolved in a solvent. In particular, the coating contains a single-component elastomer (particularly formed from an isocyanate, a polyol, and a chain extender or crosslinker) in solution in the solvent. The film forms spontaneously during solvent evaporation. The solvent is an organic solvent and may be selected from the group consisting of aromatic solvents, alcohols, ketones, esters, dimethylformamide, and n-methylpyrrolidone. In one 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-methylpyrrolidone, and mixtures of at least two of the above, such as a mixture of toluene and isopropanol.

[0052] In one embodiment, the solvent-phase polyurethane can be characterized by its concentration of non-crosslinked PU, particularly a single-component elastomer, relative to the mixture of PU and solvent of 20% to 50% by weight. In one embodiment, this solvent-phase polyurethane, particularly an elastomer in solution in a solvent, can be characterized by a viscosity (according to standard DIN EN ISO / A3) of less than 100,000 mPa.s at 23°C, preferably in the range of 5,000 to 60,000 mPa.s at 23°C.

[0053] In particular, the drying and crosslinking step involves first drying, for example at a temperature in the range of about 90 to about 120°C, followed by crosslinking at a temperature in the range of about 140 to about 210°C.

[0054] The fabric coating composition of the present invention can further comprise additives. The additives can be any additives commonly used in fabric coating compositions. They are particularly selected from the group consisting of viscosity modifiers, UV stabilizers, dyes, dispersants, and surfactants. In one embodiment, the coating comprises an anti-UV agent.

[0055] In one embodiment, the method includes one or more post-treatment steps, after the drying and cross-linking steps, to impart soil- and / or water-repellent properties to the fabric. The term "soil-repellent treatment" is understood to refer to a treatment using an antistatic and / or anti-blocking product. The term "water-repellent treatment" is understood to refer to a treatment using a fluorinated resin, with or without a cross-linking agent for the fluorinated resin, such as an isocyanate. The water-repellent treatment is followed by a drying / cross-linking step. In one embodiment, the post-treatment is applied by any method known to those skilled in the art, and in particular by padding, coating, spraying, or plasma treatment.

[0056] The present invention has the advantage of using fine yarns containing a large number of constituent fibers. In addition to imparting lightness to the fabric, this allows the porosity of the fabric to be significantly reduced prior to coating, especially if the coating is preceded by a step of opening up the fibers by calendering, which reduces the polymer uptake and therefore the relative mass of the coating, and finally, this also allows the final mass of the fabric to be reduced while still ensuring that the fabric has good properties in terms of porosity and durability.

[0057] It has been found that the coated fabrics described herein can be printed by the so-called sublimation printing technique. According to one embodiment of the invention, the coated fabrics are colored, printed, or decorated by sublimation techniques. The latter is carried out by printing a pattern on a substrate (transfer substrate) with one or more dyes that can be sublimated, especially at high temperatures. This substrate is then applied in contact with the coated fabric and then thermally calendered under pressure, for example at about 200°C. The dyes migrate into the gas phase and migrate into the coating and / or to the surface and / or into the fabric. Polyester PET remains stable at these temperatures.

[0058] An object of the present invention also relates to the lightweight fabrics that are obtained or can be obtained by carrying out the method according to the invention.

[0059] An object of the present invention therefore also relates to an article comprising or made from a fabric according to the invention, such as a glider wing, in particular a paraglider wing, which is capable of carrying a sublimation printed pattern.

[0060] The fabrics of the present invention advantageously exhibit high durability, particularly high water stability, which can be assessed by various accelerated aging methods described in the Examples section. Porosity after hydrolysis and mechanical loading: The porosity should preferably be 20 L / m according to standard NFG07111 2 / min or less, especially 12L / m 2 / min or less, especially 10L / m 2 / min or less, and / or Water absorption of less than 1%, in particular less than 0.9%, e.g. less than 0.5%, either new or after aging, according to standard Tappi 441 om-90.

[0061] The present invention is described below using examples that represent preferred embodiments, which are provided for illustrative purposes and are not intended to be limiting in any way. [Example]

[0062] This example compares the effect of a polyurethane coating on one surface of a conventional polyamide 6.6 coated with PU (control) to a high tenacity polyethylene terephthalate (PET) fabric coated on one surface with PU according to the present invention.

[0063] PA6.6 is a polyamide fabric commonly used in the paragliding sector, but with a PU elastomer with a modulus of 2 MPa at 100% elongation and a PU coating made from an isocyanate + melamine formaldehyde crosslinker. The ratio of dry crosslinker to dry elastomer is 8.4%. The PU is used in a 50 / 50 mixture of toluene and isopropanol.

[0064] In Example 1, PET is coated with a PU elastomer having a modulus of 2 MPa at 100% elongation and a PU coating made from an isocyanate + melamine formaldehyde crosslinker. The ratio of dry crosslinker to dry elastomer is 8.4%. The PU is used in a 50 / 50 mixture of toluene and isopropanol.

[0065] In Example 2, the PET has a PU coating made from a PU elastomer with a modulus of 2 MPa at 100% elongation and an isocyanate + melamine formaldehyde crosslinker. The ratio of dry crosslinker to dry elastomer is 15.4%. The PU is used in a 50 / 50 mixture of toluene and isopropanol.

[0066] In both cases, the PU is a single-component PU based on aliphatic polycarbonate.

[0067] The tenacity of this PET is 6.25 c / dtex. The elongation at break is 24.6%.

[0068] The coating is applied by means of a doctor blade and then followed by a step of drying at 100° C. and then a step of crosslinking at 180° C. The speed is 27 m / min.

[0069] [Table 1]

[0070] NF EN ISO 2062: Method A of this standard is used to measure the breaking strength and elongation at break of individual yarns using a constant speed elongation tester. Breaking Force (unit: centinewtons, cN): The maximum force that can be applied to break a specimen during a tensile test that results in failure. Elongation at break (%): The percentage increase in length of the sample measured at the time of breaking. Tenacity (cN / tex): The quotient of the breaking force expressed in cN divided by the linear density of the yarn expressed in dtex (1 tex = 1 g / 1000 m of yarn length). This test makes it possible to measure the characteristic variables of the yarn: the force at break and the elongation of the sample. The yarn is placed between two fixed clamps spaced 500 mm apart. The device (dynamometer) then moves the clamps away from each other at a travel speed of 500 mm / min and continuously measures the applied force. The force required to break the yarn is measured, as well as the rate of increase in yarn elongation at break. Average break force and average elongation at break are two data points characterized by this test. Tenacity is calculated by dividing the break force by the linear density.

[0071] The modulus of elasticity at 100% elongation of single-component polyurethane elastomers is measured in accordance with standard DIN 53504. The modulus is specified in 3.4 of the standard "Spannungswerte (Tension Values)." Measurements were performed on specimens of type S2 dumbbell shape, but with a bar length ls of 55 mm and a thickness of 200 μm. The equipment used was a dynamometer. The dumbbell specimens were placed on fixed clamps spaced apart by a length L0 with the smallest possible initial load. The clamps were then moved apart at a constant speed of 400 mm / min, and the applied force was measured in the dynamometer as a function of elongation. The modulus of elasticity or stress in MPa at 100% elongation is the ratio of the force to the initial cross-section of the specimen measured at 100% elongation. This is described in the Spannungswerte of standard DIN 53504, paragraph 9.4.

[0072] Porosity and water absorption must be and are evaluated for new and aged cases.

[0073] The porosity of the hydrolyzed fabric is also measured over time. To do this, the fabric is placed in a "Cocotte Minute" pressure cooker at operating temperature and pressure with water for 4 hours. The fabric is then treated for 1 hour by floating it in open air at high speed, and the fabric is clamped to a mill-type assembly (a four-blade assembly, the fabric is clamped to the end of one of the blades).

[0074] The water absorption rate of new and aged specimens must be measured according to standard Tappi 441 om-90. It is expressed as a percentage. The apparatus consists of a square rubber substrate and a metal ring covering, the base of which is in contact with a rubber gasket. The specimen is placed on the square substrate, and the metal ring is placed on the specimen. A clamping device is used to make the system watertight. A specific amount of water (100 mL) is placed in the ring and allowed to contact the specimen for a specified time (1 minute). After that time, the water is removed from the cylindrical ring, and the residual water remaining on the specimen's surface is removed without pressure using a cylinder, as described in this standard, by reciprocating the cylinder against the specimen placed between two sheets of blotting paper. The percentage of water absorbed is determined by calculating the difference in mass before and after contact with water.

[0075] The porosity, new and after aging, must be and is measured according to standard NFG 07111 or standard NF EN ISO 9237: Determination of the air permeability of fabrics; the latter replaces the former but gives the same results. The sample is mounted on a circular sample holder. Suction is started so that a vacuum of 2000 Pa is created, which induces an air flow through the sample. The flow rate of this flow is measured and expressed in L / m 2 / min.

[0076] The percent elongation of the fabric must be, and was, measured under a force of 3 pounds (lbs) applied across the bias. This elongation characterizes the tenacity of the fabric across the bias. The standard used is NF EN ISO 13934-1. Test specimens are made with a width of 50 mm and a length of 300 mm. The clamps of the dynamometer are moved 200 mm apart from each other, and measurements must be, and were, made at a rate of 100 mm / min.

[0077] Example 2: This example compares the effect of tenacity on PET yarns. [Table 2]

[0078] In the above example, "Control Low Tenacity PET," the PET has a tenacity of 4.3 cN / dtex, lower than the tenacity of the yarn used in this invention. The fabrics in both cases have a PU elastomer with a modulus of 2 MPa at 100% elongation and a PU coating derived from an isocyanate + melamine formaldehyde crosslinker. The ratio of dry crosslinker to dry elastomer is 15.4% in both tests. The PU was used in a 50 / 50 mixture of toluene and isopropanol, and the formulation was the same for both tests.

[0079] The elongation at bias of the control fabric was less than the 5.2% of the inventive example, and its porosity after aging was also significantly higher than that of the inventive example, a surprising result given that the coating rate in the control was higher than that of the fabric in the inventive example.

[0080] Example 3: This example shows the effect of the PU modulus at 100% elongation. [Table 3]

[0081] The "Control PET" example has a PU coating made from a PU elastomer with a modulus of 8 MPa at 100% elongation and a melamine formaldehyde crosslinker. The dry crosslinker to dry elastomer ratio is 15.1%. This PU is used in a 50 / 50 mixture of toluene and isopropanol in the same manner as in the other examples. The fabric substrate is the same.

[0082] The use of a PU with a modulus of 8 MPa at 100% elongation results in the outward elongation envisaged by the present invention in the bias direction, and a very high porosity after aging.

[0083] The water absorption of the fabrics of the present invention is remarkable. Furthermore, it has been found that the fabrics are also printable by sublimation printing. Finally, the fabrics of the present invention have a high level of porosity stability over time, a performance that was unexpected.

Claims

1. 1. A fabric for hang glider wings, particularly for paraglider wings, formed from continuous warp and weft yarns and coated on one or both of its two surfaces with polyurethane (PU), the uncoated fabric having a coverage factor TC in the range of 1.8 to 4, TC being calculated according to the formula TC = ((number of yarns / cm) x (diameter of one yarn in cm)) (warp yarns) + ((number of yarns / cm) x (diameter of one yarn in cm)) (weft yarns), the yarns being made from poly(ethylene terephthalate) (PET), the PET having a tenacity in the range of 6 to 7 cN / dtex, the fabric having a density in terms of warp and weft yarn densities in the range of 30 to 50 yarns / cm, the polyurethane being a crosslinked polyurethane (PU) based on polyether, polyester, or polycarbonate, and the PU being: (1) a crosslinked polyurethane (PU) based on a standard DIN 53504, and characterized in that it is derived from crosslinking of a single-component polyurethane, which is used in an organic solvent phase in practice, with a crosslinking agent based on a ratio of dry crosslinking agent to dry elastomer in the range of 5% to 30% by weight.

2. 10. The fabric of claim 1, wherein the single-component polyurethane has a modulus of elasticity in the range of 1 to 4 MPa at 100% elongation according to standard DIN 53504.

3. 10. The fabric of claim 1, wherein the single-component polyurethane has a modulus of elasticity in the range of 1 to 3 MPa at 100% elongation according to standard DIN 53504.

4. The fabric according to any one of claims 1 to 3, wherein the ratio of the dry crosslinking agent to the dry elastomer is in the range of 7% by mass to 20% by mass.

5. The fabric of claim 4, wherein the ratio of dry crosslinker to dry elastomer is in the range of 8% to 18% by weight.

6. The fabric of any one of claims 1 to 3, wherein the uncoated fabric has a coverage factor TC in the range of 2.6 to 3.

2.

7. 4. The fabric of claim 1, wherein the PET yarns have an elongation at break according to standard DIN EN ISO 2062 of 20% or more.

8. 8. The fabric of claim 7, wherein the PET yarns have an elongation at break according to standard DIN EN ISO 2062 in the range of 20% to 30%.

9. The fabric has a weight of 25 to 42 g / m, including the coating. ２ The fabric of any one of claims 1 to 3, having a mass in the range of

10. The fabric according to any one of claims 1 to 3, wherein the dry absorption rate of the coating material is 10% by mass or more.

11. The fabric of claim 1, wherein the fabric comprises warp and weft yarns having a dtex in the range of 11 to 44 dtex.

12. 12. The fabric of claim 11, wherein the fabric comprises warp and weft yarns having a dtex of 11 to 33 dtex.

13. 13. The fabric of claim 11 or 12, wherein the fabric comprises warp and weft yarns having a DPF (decitex per fiber) in the range of 1-4.

14. The fabric of any one of claims 1 to 3, wherein the crosslinking agent of the PU is an isocyanate, a polyisocyanate, a melamine, a mixture containing melamine, or a mixture of an isocyanate and a melamine.

15. The fabric is 100 cm ２ 20 L / m measured under a pressure of 2000 Pa over a measured surface area of ２ 4. The fabric of claim 1, having a breathability of 1 / min or less and / or a water absorption of 1% or less, either new or after aging, measured according to standard Tappi 441 om-90.

16. 4. The fabric of any one of claims 1 to 3, wherein the fabric has an elongation of 10% or less under 3 lbs according to standard NF EN ISO 13934-1 on bias along the warp and weft directions.

17. 17. The fabric of claim 16, wherein the fabric has an elongation in the range of 1% to 10% under 3 lbs according to standard NF EN ISO 13934-1 on bias along the warp and weft directions.

18. 17. The fabric of claim 16, wherein the fabric has an elongation in the range of 5% to 10% under 3 lbs according to standard NF EN ISO 13934-1 on bias along the warp and weft directions.

19. A glider wing comprising the fabric of any one of claims 1 to 18.

20. 20. The glider wing of claim 19, wherein the glider wing is a paraglider wing.

21. 21. The glider wing of claim 19 or 20, wherein the glider wing has a dye-sublimation printed pattern.

22. A method for producing the coated fabric according to any one of claims 1 to 18, comprising: a fabric is provided, said fabric being made of poly(ethylene terephthalate) (PET) having a density in the range of 30 to 50 threads / cm for warp and weft densities; one or both of the two surfaces of this fabric is coated using a mixture of a one-component polyurethane elastomer having a modulus of elasticity of less than or equal to about 5 MPa at 100% elongation according to standard DIN 53504, a solvent for said elastomer, and a crosslinker, based on a ratio of dry crosslinker to dry elastomer ranging from about 5% to about 30% by weight; The fabric is dried and heated until the coating is crosslinked; - A coated fabric is obtained, method.

23. 23. The method of claim 22, wherein the coated fabric is printed on one or both of its two surfaces by sublimation printing.

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