ELASTIC FABRIC, AND OCCULTING DEVICE INCLUDING SUCH FABRIC

Abstract

A fabric with a weft elasticity greater than 5% and a warp elasticity, comprising exclusively elastic yarns in the weft, characterized in that the weft yarns are covered yarns having an elastic core and at least one cover yarn wound around the core yarn, wherein: - the count of the covered yarn is less than 200 tex, - the number of turns of the cover yarn around the core yarn is between 200 and 2500 turns per meter, - the cover yarn is a multifilament with a count between 5 and 70 tex

Description

Title of the invention: ELASTIC FABRIC, AND HIDDEN DEVICE INCLUDING SUCH A FABRIC Technical field

[0001] The invention relates to the field of solar protection devices, and more particularly to occultation devices intended to be installed in front of building openings, comprising a screen which can be unrolled, manually or automatically, to end up covering all or part of the surface of the opening, through which light can penetrate.

[0002] It more specifically aims at a textile structure particularly adapted to form this screen, by giving the device an adjustable occultation rate.

[0003] The invention also relates to a screening device equipped with such a textile. Prior art

[0004] Generally speaking, screens of this type of device have a light transmission rate that is constant over their entire surface, and which is defined by the structure of the material forming the screen. In particular when it is a fabric, the transmission rate is directly linked to the opening rate of the fabric. Thus, when it is desired to adjust the quantity of light entering through the opening, it is necessary to unroll the sheet over a fraction of the height of the opening. This operation makes it possible to adjust the overall quantity of light entering the room, but certain areas of the room remain subject to full light radiation. There is therefore a need to be able to completely obscure an opening with an adjustable light transmission rate.

[0005] A solution has been proposed in document EP 2 847 411 which describes a light occultation device, equipped with an extensible screen whose light transmission rate varies according to the stretching rate of the sheet forming the screen. Thus, when the screen is unrolled so as to occupy the entire surface of the opening, a mechanism exerts traction on the screen so as to extend the latter, and to increase its opening rate, and thus allow a greater quantity of light radiation to pass through.

[0006] Various screen structures have already been proposed, such as perforated or elastic films, or even textile structures such as those described in documents EP3385493, US2015 / 247267 or BE1027899. The textile described in the latter document has warp threads which have a certain degree of elasticity. In this way, when this textile is stretched in the warp direction, the weft threads move away from each other, and the opening rate of the textile increases, allowing a greater quantity of light to pass through.

[0007] Several problems arise with the textile described in this document. Indeed, the elastic threads are arranged in the warp direction of the fabric, and the stretching of the textile must therefore take place in the warp direction to ensure the desired adjustment. However, the use of elastic threads as warp threads poses problems of control of the manufacturing process, in particular during warping and also during weaving. Furthermore, since the fabrics have a determined width fixed by the width of the loom, it is necessary to assemble several sections of fabric in parallel if one wishes to produce devices of great width. The assembly of these different sections is therefore done according to the direction of the warp threads, which creates a slight excess thickness of the textile at this level.The presence of these excess thicknesses is a source of creases when the fabric is rolled up, which makes it completely unsuitable for the production of large-width screening devices. In addition, a weld required to produce this assembly has an inextensible character, which disrupts or even blocks the elasticity of the screen in the warp direction, and therefore makes it incapable of having a variable rate of light transmission. Furthermore, this type of textile is by definition exposed to light radiation, and it is known that the materials constituting the elastic threads are generally very sensitive to solar radiation, and degrade under the effect of ultraviolet radiation. A problem therefore arises regarding the durability of the elastic threads of this type of fabric over time, their conservation and integrity, or at least their elastic properties. Statement of the invention

[0008] There is therefore a need to produce screens whose light permeability is adjustable with the degree of extension of the screen, and which can be produced without limitation of width, while retaining elastic properties that last over time, and without increasing their mass too much.

[0009] To this end, the Applicant has designed a fabric having an elasticity rate in the weft direction greater than 5%, and inelastic in the warp direction, and which comprises exclusively elastic threads in the weft. In accordance with the invention, the elastic weft threads are covered threads comprising an elastic core and at least one covering thread wound around the core in which: - the count of the covered yarn is less than 200 tex, preferably less than 180 tex, - the number of turns of the covering yarn around the core yarn is between 200 and 2500 turns per meter, preferably between 500 and 2000 turns per meter, and very preferably between 700 and 1500 turns per meter, - the covering thread is a multi-filament with a count between 5 and 70 tex, preferably between 8 and 60 tex.

[0010] In other words, the textile according to the invention is made up in the weft direction exclusively of elastic yarns whose elastic core is protected by a covering yarn which prevents or at least greatly limits the exposure of this core yarn to ultraviolet rays. More precisely, the covering yarn itself has the properties of blocking ultraviolet rays, increasing the life of the elastic core. The choices of the different counts of the core yarn, the covering yarn, and the rate of coverage of the core yarn by the covering yarns make it possible to obtain a minimum fabric elongation rate of 5%, which can go up to 30%, or even 40% and even 50% elongation, while ensuring protection of the elastic part of the weft yarns.Stretch is measured as the rate of elongation, that is, the ratio between the length of the tissue on which a tensile stress is exerted, and the length of the tissue at rest, when it is not subjected to any tensile stress.

[0011] Furthermore, the presence of elastic threads in the weft direction makes it possible to make fabrics for very wide blinds, since these weft threads are oriented in the unwinding direction of the screen, and the width of the screen is measured in the warp direction of the fabric, without any real manufacturing limitation. When the textile according to the invention used has a width, measured in the weft direction, which is less than the desired length of the screen, it is appropriate to assemble several sections of fabric, by welding or the like, along a line parallel to the warp direction of the fabric, and therefore perpendicular to the winding direction of the screen. It follows that the excess thickness generated by this assembly is parallel to a generatrix of the winding cylinder, and therefore creates an excess thickness distributed over the entire width of the winding, thus limiting, or even eliminating the risk of creases appearing.

[0012] Different types of materials can be used to form the core threads of the elastic threads, in particular materials from the polyurethane family, and typically elastanes, but also possibly elastodiene-based threads, or silicone-based threads. It is also possible to use materials from the elastolefin family, which are fibers composed so that almost all of them are partially crosslinked macromolecules based on one or more olefins, and which after treatment adopt elastic properties. Examples of such elastolefins are described in documents WO 99 / 60 060 or CN115652476.

[0013] As mentioned, the protection of the elastic core yarn is ensured by the covering yarn wound around the core yarn. Depending on the desired elongation rates and the materials used, it is possible to use a single covering, i.e. a winding of a single covering yarn, but also a double covering, i.e. a winding of two covering yarns wound around the same core yarn. In a preferred embodiment, the two yarns are wound around the core yarn in different directions, to optimize the coverage rate and the torsional behavior of the covered yarn. Of course, higher order coverings can also be considered.

[0014] In the particular case of a core yarn having sensitivity to ultraviolet radiation, it is important to ensure maximum coverage of the core yarn, and thus, in the context of the use of an elastane core, the number of turns of covering yarns around the core yarn is chosen so that at a stretch of 60% of the covered yarn, the covering yarns completely cover the core yarn. In other words, when the covered yarn is stretched, the core yarn lengthens and the turns formed by the covering yarn move relative to each other.In this particular case, the number of turns of the cover yarn is chosen so that at a given stretch, no fraction of the core yarn is visible when observing the yarn, for example with image analysis tools.

[0015] As regards the covering yarns, different materials can be used, provided that they have ultraviolet radiation blocking properties. Among the materials envisaged, mention may be made in particular of polyamides, polyesters, polyacrylics, polypropylene, glass and carbon, taken individually or as a mixture.

[0016] Advantageously, the covering yarns are multi-filaments, thus allowing the covering yarns to spread during elongation of the covered yarn, and to continue to ensure optimal coverage over the entire elongation range of the covered yarn.

[0017] Advantageously in practice, the covering yarns have a count of less than 700 decitex, preferably less than 600 decitex. In this way, the total thickness of the textile remains within limited ranges, with the aim of not creating too much excess thickness when rolling up the screen. Examples of embodiments of the invention

[0018] As already mentioned, the invention relates to a woven textile, which incorporates elastic threads in the weft direction.

[0019] More precisely, these elastic threads are covered threads, comprising a core thread on which one or more covering threads are wound.

[0020] In a first example, the core yarn is a yarn of the reference D850F48102 DB marketed by the company XLANCE with a count of 850 decitex. The core yarn is covered by two identical covering yarns wound, one in the S direction and the other in the Z direction. The covering yarn is a polyester-based multi-filament. More precisely, the yarn comprises 48 elementary filaments assembled and twisted, with an overall count of 150 decitex. The covering yarns are wound onto the core yarn by a traditional covering process. The number of turns of the first covering yarn on the core yarn is 700 rpm, the number of turns of the second covering yarn on the core yarn is 900 rpm measured according to standard ASTM D 1423 / 03.

[0021] The tests were also carried out to verify the resistance of the yarn to ultraviolet radiation and demonstrate that the yarn retains its elastic stiffness properties almost unchanged after a period ten times longer than that after which an equivalent core yarn without a covering yarn has lost its stiffness.

[0022] A fabric was made from this covered yarn, using polyvinyl chloride-coated polyester yarns in the warp, and the covered yarn described above in the weft. The weave was made in a 2 / 1 basket weave, also called Louisine 2 / 1, with warp yarns of a count of 1400 decitex, and 6 yarns per centimeter in the weft.

[0023] This fabric therefore has a stretching capacity in the weft direction, and its opening rate is less than 1% for zero elongation, and 10% for 25% elongation. The thickness of the fabric in an unstretched state is 0.8mm.

[0024] A second embodiment was carried out using as core yarn an elastane-based yarn (polyurethane), with a count of 940 decitex. The core yarn is covered by two identical covering yarns wound, one in the S direction and the other in the Z direction. The covering yarn is a polyester-based multi-filament. More precisely, the yarn comprises 48 elementary filaments assembled and twisted, with an overall count of 150 decitex. The covering yarns are wound onto the core yarn by a traditional covering process. The number of turns of the first covering yarn on the core yarn is 760 rpm, the number of turns of the second covering yarn on the core yarn is 1090 rpm measured according to standard ASTM D 1423 / 03

[0025] A fabric was made from this covered yarn, using polyvinyl chloride-coated polyester yarns in the warp, and the covered yarn described above in the weft. The weave was made in plain weave, with warp yarns of a count of 1400 decitex, and 6 threads per centimeter in the weft.

[0026] This fabric therefore has a stretching capacity in the weft direction, and its opening rate is 0.1% for zero elongation, and 10% for an elongation of 22.5%.

[0027] Such a textile has the advantage of being able to be used in a device such as described in patent EP 2 847 411.

Claims

Claims

1. Fabric having an elasticity rate in the weft direction greater than 5%, and inelastic in the warp direction, comprising exclusively elastic threads in the weft, characterized in that the weft threads are covered threads comprising an elastic core and at least one covering thread wound around the core thread, in which: - the count of the covered thread is less than 200 tex, - the number of turns of covering thread around the core thread is between 200 and 2500 turns per meter, - the covering thread is a multifilament whose count is between 5 and 70 tex

2. Fabric according to claim 1 characterized in that the core yarn is made of a material from the polyurethane family, typically elastane.

3. Fabric according to claim 1 characterized in that the core yarn is made of a material chosen from the family of elastolefins, elastodienes and silicones.

4. Fabric according to claim 1 characterized in that the core yarn is covered with several covering yarns.

5. Fabric according to claim 4 characterized in that the cover yarns are wound in two different directions around the core yarn.

6. Fabric according to claim 2 characterized in that the number of turns of the covering yarns around the core yarn is chosen so that in a state of stretching of the covered yarn of 60%, said covering yarns completely cover the core yarn.

7. Fabric according to claim 2 characterized in that the covering yarns are multifilament yarns based on a material chosen from the group comprising polyamides, polyesters, polyacrylics, polypropylenes, glass and carbon.

8. Device for obscuring light radiation including a roll-up screen formed by a fabric according to one of claims 1 to 7, having its weft threads parallel to the direction of unrolling of the screen.