Elastic fabric and shading device including such a fabric

Abstract

The invention relates to a fabric that has an elasticity greater than 5% in the weft direction and is inelastic in the warp direction, including exclusively elastic yarns in the weft, characterised in that the weft yarns are covered yarns including an elastic core and at least one covering yarn wound around the core yarn, wherein: - the yarn count of the covered yarn is less than 200 tex; - the number of turns of covering yarn around the core yarn is between 200 and 2500 turns per meter; and - the covering yarn is a multifilament, the yarn count of which is between 5 and 70 tex.

Description

[0001] DESCRIPTION

[0002] TITLE: ELASTIC FABRIC, AND SCREEN-OUT DEVICE INCLUDING SUCH A FABRIC

[0003] Technical field

[0004] 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.

[0005] It more specifically targets a textile structure particularly suited to forming this screen, giving the device an adjustable occultation rate.

[0006] The invention also relates to a screening device equipped with such a textile.

[0007] Previous techniques

[0008] 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. Particularly when it is a fabric, the transmission rate is directly linked to the opening rate of the fabric. Thus, when one wishes 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.

[0009] A solution has been proposed in document EP 2 847 411 which describes a light occultation device, equipped with an extendable 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.

[0010] Various screen structures have already been proposed, such as perforated or elastic films, or textile structures such as those described in documents EP3385493, US2015 / 247267 or BE1027899. The textile described in the latter document has warp threads that have a certain degree of elasticity. As a result, when this textile is stretched in the warp direction, the weft threads move apart from each other, and the openness rate of the textile increases, allowing a greater quantity of light to pass through.

[0011] There are several problems with the textile described in this document. 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 in controlling the manufacturing process, particularly during warping and also during weaving. Furthermore, since the fabrics have a specific width determined by the width of the loom, it is necessary to assemble several sections of fabric in parallel if one wishes to produce large-width devices. 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 preservation and integrity, or at least their elastic properties.

[0012] Statement of the invention

[0013] 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 declined without limitation of width, while retaining elastic properties lasting over time, and without increasing their mass too much. 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:

[0014] - the count of the covered yarn is less than 200 tex, preferably less than 180 tex,

[0015] - 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,

[0016] - the covering yarn is a multi-filament yarn with a count between 5 and 70 tex, preferably between 8 and 60 tex.

[0017] In other words, the textile according to the invention is made 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 service 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.

[0018] 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.

[0019] Different types of materials can be used to form the core yarns of elastic yarns, in particular materials from the polyurethane family, and typically elastanes, but also possibly elastodiene-based yarns, or even silicone-based yarns. 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.

[0020] 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 mode, the two yarns are wound around the core yarn in different directions, to optimize the covering rate and the torsional behavior of the covered yarn. Of course, higher-order coverings can also be considered.

[0021] In the particular case of a core yarn with sensitivity to ultraviolet radiation, it is important to ensure maximum coverage of the core yarn, and thus, when using an elastane core, the number of turns of cover yarns around the core yarn is chosen so that at a 60% stretch of the covered yarn, the cover 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 cover 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.

[0022] Regarding the covering yarns, different materials can be used, as long as they have ultraviolet radiation blocking properties. Among the materials considered, we can notably cite polyamides, polyesters, polyacrylics, polypropylene, glass and carbon, taken individually or in mixtures.

[0023] Advantageously, the covering yarns are multi-filaments, thus allowing the covering yarns to spread out as the covered yarn is stretched, and to continue to provide optimum coverage over the entire stretch range of the covered yarn.

[0024] 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.

[0025] Examples of embodiments of the invention

[0026] As already mentioned, the invention relates to a woven textile, which incorporates elastic threads in the weft direction.

[0027] More precisely, these elastic threads are covered threads, comprising a core thread on which one or more covering threads are wound.

[0028] 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, one wound 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 using 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.

[0029] The tests were also carried out to verify the yarn's resistance 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.

[0030] 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 threads per centimeter in the weft.

[0031] This fabric therefore has a stretch 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 0.8 mm.

[0032] A second example of realization was made using as core yarn an elastane-based yarn (polyurethane), with a count of 940 decitex. The core yarn is covered by two identical cover yarns wound, one in the S direction and the other in the Z direction. The cover 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 cover yarns are wound on the core yarn by a traditional covering process. The number of turns of the first cover yarn on the core yarn is 760 rpm, the number of turns of the second cover yarn on the core yarn is 1090 rpm measured according to the ASTM D 1423 / 03 standard.

[0033] 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.

[0034] This fabric therefore has a stretch capacity in the weft direction, and its opening rate is 0.1% for zero elongation, and 10% for an elongation of 22.5%.

[0035] Such a textile has the advantage of being able to be used in a device 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 title of the covered yarn is less than 200 tex, - the number of turns of the covering yarn around the core yarn is between 200 and 2500 turns per meter, - the covering thread is a multifilament with a count 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 covering threads are wound in two different directions around the core thread.

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 occulting 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.