Elastic fabric and shading device comprising the same

Abstract

A fabric having an elasticity in the weft direction greater than 5% and which is inelastic in the warp direction, comprising only elastic yarns in the weft direction, characterized in that the weft yarns are covered yarns comprising an elastic core and at least one covering outer layer yarn wound around said core yarn, wherein: - the linear density of the covered yarn is less than 200 dtex, - the number of turns of the covering outer layer yarn around the core yarn is between 200 and 2500 turns per meter, - the covering outer layer yarn is a multifilament with a linear density between 5 and 70 dtex.

Description

Technical Field

[0001] This invention relates to the field of shading devices, and more particularly to shading devices intended for installation in front of a building's skylight, the shading device comprising a manually or automatically deployable shield that ultimately covers all or part of the surface area of ​​the skylight through which light can pass.

[0002] More specifically, the present invention relates to a textile structure particularly suitable for forming the shield by imparting an adjustable shading rate to the device.

[0003] The present invention also relates to a light-blocking device equipped with such a textile. Background Technology

[0004] Typically, the cover of such devices has a constant light transmittance over its entire surface area, and this transmittance is defined by the material structure forming the cover. Specifically, when it is a fabric, the transmittance is directly related to the fabric's aperture coefficient. Therefore, when it is desired to adjust the amount of light entering through the light opening, a portion of the sheet must be unfolded along the height of the door. This adjusts the total amount of light entering the room, but some areas of the room still receive sufficient light radiation. Therefore, there is a need for a light opening that can be completely covered with adjustable transmittance.

[0005] Document EP 2 847 411 proposes a solution describing a light-shielding device equipped with an extendable shield whose light transmittance varies with the elongation of the sheet forming the shield. Therefore, when the shield is unfolded to occupy the entire surface area of ​​the light-receiving opening, the mechanism applies tension to the shield to extend it and increase its aperture factor, thereby allowing a greater amount of light radiation to pass through.

[0006] Various shielding structures have been proposed, such as perforated or elastic films, or textile structures as described in documents EP3385493, US2015 / 247267, or BE1027899. The textiles described in the latter document have warp yarns exhibiting a degree of elasticity. Thus, when the textile is stretched in the warp direction, the weft yarns move away from each other, and the opening factor of the textile increases, allowing a greater amount of light to pass through.

[0007] The textiles described in the latter document present several problems. In fact, the elastic yarns are laid out in the warp of the fabric, thus requiring the textile to be stretched in the warp to ensure the necessary adjustment. However, using elastic yarns as warp yarns creates difficulties in controlling the manufacturing process, particularly during warping and weaving. Furthermore, since the fabric has a predetermined width determined by the loom width, when intending to manufacture wide-width devices, it is necessary to splice several pieces of fabric side-by-side. Therefore, these different pieces are spliced ​​according to the warp direction, resulting in a slight increase in the thickness of the textile at this location. The presence of these areas of increased thickness can lead to wrinkles when the fabric is rolled up, making it completely unsuitable for producing wide-width shading devices. Moreover, the weld seams required to form such splices are non-stretchable, thus impairing or even hindering the elasticity of the shading in the warp direction and therefore preventing it from providing variable light transmittance. Furthermore, by definition, this type of textile is exposed to light radiation, and the materials constituting the elastic yarns are known to be generally very sensitive to solar radiation and degrade under the influence of ultraviolet radiation. Therefore, problems arise regarding the long-term durability, preservation and integrity, or at least the elastic properties of the elastic yarns in such fabrics. Summary of the Invention

[0008] Therefore, there is a need for a shield that can adjust its light transmittance as the shield extends, can be produced without width limitations, maintains durable elasticity over time, and does not excessively increase its weight.

[0009] To this end, the applicant designed a fabric with greater than 5% elasticity in the weft direction and inelasticity in the warp direction, comprising only elastic yarns in the weft direction. According to the present invention, the elastic weft yarn is a covered yarn (fils guipés), comprising an elastic core and at least one covered outer yarn (fil de couverture) wrapped around the core yarn, wherein: - The linear density of the covered yarn is less than 200 tex, preferably less than 180 tex. - The number of wraps of the outer layer yarn around the core yarn is between 200 and 2500 per meter, preferably between 500 and 2000 per meter, and very preferably between 700 and 1500 per meter. - The outer layer yarn is multifilament with a linear density between 5 and 70 tex, preferably between 8 and 60 tex.

[0010] In other words, the textile according to the invention consists only of elastic yarns in the weft direction, and its elastic core is protected by a covering outer yarn that prevents or at least substantially limits the core yarn's exposure to ultraviolet light. More specifically, the covering outer yarn itself has ultraviolet-blocking properties, thereby increasing the lifespan of the elastic core. Different linear densities of the core yarn, the covering outer yarn, and the degree to which the covering outer yarn covers the core yarn allow for a minimum elongation of 5% for the fabric, while elongation can reach up to 30%, 40%, or even 50%, while ensuring protection of the elastic portion of the weft yarns. Stretching is measured as elongation, which is the ratio between the length of the fabric under tensile stress and its length at rest without any tensile stress.

[0011] Furthermore, the presence of weft elastic yarns enables the production of fabrics for extremely wide Venetian blinds, as these weft yarns are oriented in the unfolding direction of the blinds, and the width of the blinds, measured in the warp direction of the fabric, has no significant manufacturing limitations. When the width of the textile used according to the invention, measured in the weft direction, is less than the required blind length, multiple pieces of fabric can be joined together by welding or similar means along a line parallel to the warp direction of the fabric and therefore perpendicular to the rolling direction of the blinds. Thus, the increase in thickness at this joint is parallel to the generatrix of the winding cylinder, and therefore produces an increase in thickness distributed across the entire winding width, thereby limiting or even eliminating the risk of wrinkles.

[0012] Various types of materials can be used to form the core yarn of elastic yarns, particularly those from the polyurethane family, and typically spandex, but also, where appropriate, yarns based on elastomeric dienes or silicone-based yarns. Materials from the elastomeric olefin family can also be used; these are fibers composed almost entirely of partially cross-linked macromolecules based on one or more olefins and exhibit elastic properties after treatment. Examples of such elastomeric olefins are described in documents WO 99 / 60 060 and CN115652476.

[0013] As described above, the protection of the elastic core yarn is provided by the outer covering yarn wound around it. Depending on the required elongation and the material used, a single wrap (i.e., a single outer covering yarn) or a double wrap (i.e., two outer covering yarns wound around the same core yarn) can be used. In a preferred embodiment, the two yarns are wound around the core yarn in different directions to optimize the coverage and the torsional behavior of the outer covering yarn. Of course, higher-order wrap arrangements can also be considered.

[0014] In the specific case of a core yarn sensitive to ultraviolet radiation, ensuring maximum coverage of the core yarn is important. Therefore, when using spandex core yarn, the number of turns of the outer wrapping yarn around the core yarn is selected such that when the outer wrapping yarn is stretched by 60%, it completely covers the core yarn. In other words, as the outer wrapping yarn stretches, the core yarn stretches, and the number of turns formed by the outer wrapping yarn shifts relative to each other. In this specific case, the number of turns of the outer wrapping yarn is selected such that, at a given stretch, no part of the core yarn is visible when observing the yarn, for example, using an image analysis tool.

[0015] Regarding the outer covering yarn, various materials can be used, as long as they possess the property of blocking ultraviolet radiation. Among the anticipated materials, polyamide, polyester, polyacrylate, polypropylene, glass, and carbon, used alone or in combination, are particularly noteworthy.

[0016] Advantageously, the outer covering yarn is multifilament, which allows the outer covering yarn to unfold during the stretching of the covering yarn and continues to ensure optimal coverage throughout the entire stretch of the covering yarn.

[0017] Advantageously, in practice, the linear density of the outer covering yarn is less than 700 dtex, preferably less than 600 dtex. This keeps the total thickness of the textile within a limited range, aiming to avoid excessive thickness when used in rolled-up coverings.

[0018] Embodiments of the present invention

[0019] As previously stated, the present invention relates to a woven textile in which elastic yarns are introduced in the weft direction.

[0020] More specifically, these elastic yarns are covered yarns, comprising a core yarn and one or more outer covering yarns wound around the core yarn.

[0021] In the first embodiment, the core yarn is XLANCE yarn, reference D850F48102 DB, with a linear density of 850 décitex. The core yarn is covered by two identical outer covering yarns, one wound in the S direction and the other in the Z direction. The outer covering yarns are polyester-based multifilaments. More specifically, the yarn comprises 48 monofilaments assembled and twisted together, with a bus density of 150 décite. The outer covering yarns are wound around the core yarn using a conventional covering process. Measured according to standard ASTM D1423 / 03, the first outer covering yarn wound around the core yarn 700 rpm, and the second outer covering yarn wound around the core yarn 900 rpm.

[0022] Tests were also conducted to examine the yarn’s resistance to ultraviolet radiation and to demonstrate that the yarn retained its essentially unchanged elastic stiffness properties after a period of time ten times longer than that of the equivalent core yarn without the outer covering yarn, which had lost its stiffness.

[0023] The fabric made from this covered yarn uses polyvinyl chloride-coated polyester yarn in the warp and the aforementioned covered yarn in the weft. The fabric is woven in a 2 / 1 weave (armure natté 2 / 1) (or also known as 2 / 1 Louisine weave), using warp yarns with a linear density of 1400 dtex and 6 yarns per centimeter in the weft.

[0024] Therefore, the fabric is stretchable in the weft direction and has an opening factor of less than 1% at zero elongation and 10% at 25% elongation. The thickness of the fabric in its unstretched state is 0.8 mm.

[0025] A second exemplary embodiment was fabricated using a spandex (polyurethane)-based yarn with a linear density of 940 dtex as the core yarn. The core yarn is covered by two identical outer covering yarns, one wound in the S-direction and the other in the Z-direction. The outer covering yarns are polyester-based multifilaments. More specifically, the yarn comprises 48 primary monofilaments assembled and twisted together, with a bus density of 150 dtex. The outer covering yarns are wound around the core yarn using a conventional covering process. Measured according to standard ASTM D 1423 / 03, the first outer covering yarn wound around the core yarn 760 rpm, and the second outer covering yarn wound around the core yarn 1090 rpm.

[0026] The fabric made from this covered yarn uses polyvinyl chloride-coated polyester yarn in the warp and the aforementioned covered yarn in the weft. The fabric is woven in a plain weave, using warp yarns with a linear density of 1400 dtex and 6 yarns per centimeter in the weft.

[0027] Therefore, the fabric is stretchable in the weft direction, with an opening factor of 0.1% at zero elongation and 10% at 22.5% elongation.

[0028] This textile has the advantage of being usable in the apparatus described in patent EP 2 847 411.

Claims

1. A fabric having greater than 5% elasticity in the weft direction and being inelastic in the warp direction, comprising only elastic yarns in the weft direction, characterized in that... The weft yarn is a covered yarn, comprising an elastic core and at least one outer covering yarn wound around the core yarn, wherein: - The linear density of the covering yarn is less than 200 tex. - The number of turns of the outer layer yarn around the core yarn is between 200 and 2500 turns per meter. - The outer layer yarn is multifilament with a linear density between 5 and 70 tex.

2. The fabric according to claim 1, characterized in that, The core yarn is made of materials from the polyurethane family, typically spandex.

3. The fabric according to claim 1, characterized in that, The core yarn is made of materials selected from the elastic olefin, elastic diene and organosilicon family.

4. The fabric according to claim 1, characterized in that, The core yarn is covered by multiple outer yarns.

5. The fabric according to claim 4, characterized in that, The outer layer yarn is wound around the core yarn in two different directions.

6. The fabric according to claim 2, characterized in that, Select the number of turns of the outer covering yarn around the core yarn such that when the covering yarn is in a 60% stretch state, the outer covering yarn completely covers the core yarn.

7. The fabric according to claim 2, characterized in that, The outer covering yarn is a multifilament yarn based on materials selected from the group consisting of polyamide, polyester, polyacrylate, polypropylene, glass, and carbon.

8. An apparatus for blocking light radiation, comprising a rolled-up shield formed of a fabric according to any one of claims 1 to 7, wherein the weft yarns are parallel to the unfolding direction of the shield.