BE1021658B1 - ELECTRICALLY CONDUCTIVE FABRIC - Google Patents

Abstract

Electrically conductive fabric, comprising: a set of electrically conductive, a set of non-electrically conductive threads and a set of evenly spaced warp-direction binding threads, a set of electrically conductive and a set of non-electrically conductive weft-direction threads, the sets of electrically conductive threads in the weft direction. warp direction and weft direction have substantially the same density and their threads have the same conductivity; the set of binding threads via a sling thread binding with the set of electrically conductive threads in warp direction provides the connection between the set of electrically conductive threads in warp direction and the set of electrically conductive threads in the weft direction.

Description

Electrically conductive fabric

Description Technical field

The invention relates to a woven electrically conductive fabric with electrical conductivity in the warp and weft direction and in the directions that make an angle with the warp and weft direction. Such electrically conductive fabrics can be used, for example, in electric heating elements, in textile electronics - these are electrical components that consist essentially of textile structures (e.g., conductive textiles, e.g., in clothing) -, as a sensor, and for electromagnetic shielding.

Technical background

Electrically conductive cloths for use in electrical heating elements or for use as a textile electronic component are known. US2004 / 173028, for example, describes the combined use of an electrically conductive cloth for heating a car seat and as a sensor. US 3,472,289 describes a number of textile fabric constructions in which metal filament yarns are used as a guide. This publication describes the use of such fabrics as a heating element. However, these fabrics are not optimal for all applications and have a series of defects in this regard.

Description of the invention

It is the object of the invention to provide an electrically conductive fabric that satisfies a combination of requirements: - sufficient isotropic electric conductivity (also and especially in conditions of use of the fabric) in warp and weft direction, but also in directions that form an angle with the warp and weft direction. Preferably, the specific surface resistance in the directions forming an angle of 45 ° with the warp and weft direction is at most six times higher than the average of the specific surface resistance in warp and weft direction. Sufficient isotropy is specifically important in conditions where the fabric will be used in applications where the electrodes are coupled to the fabric so that the straight connection between the electrodes is not in the warp or weft direction. - the fabric must have a textile character. By textile character is meant that the fabric must have a textile feel, more specifically a textile fiber feel as is obtained with fabrics based on natural fibers (cotton, wool ...) or synthetic fibers or filaments (polyester, polyamide ...) . - excellent durability under cyclic load (e.g. cyclic bending load; and with sufficient retention of the electrical conductivity values after cyclic load), and - resistant to corrosion.

Preferably, the fabric also has good air permeability and excellent electromagnetic shielding.

The objectives are achieved via an electrically conductive fabric, which comprises - a set of electrically conductive wires in the warp direction of the fabric, these wires being evenly distributed across the width of the fabric; - a set of electrically conductive threads in the weft direction of the fabric, preferably these threads are evenly distributed along the length of the fabric; - a set of non-electrically conductive wires in the warp direction of the fabric, preferably these wires are evenly distributed over the width of the fabric; - a set of non-electrically conductive wires in the weft direction of the fabric, preferably these wires are evenly distributed along the length of the fabric; - a set of binding threads in the warp direction of the fabric, these binding threads are evenly distributed over the width of the fabric; these wires are preferably non-electrically conductive, and wherein - the density of the set of electrically conductive wires in the warp direction and the density of the set of electrically conductive wires in the weft direction are substantially equal to each other; - the electrically conductive wires in the warp direction and in the weft direction have the same electrical conductivity (taken per unit of length); - the set of binding threads by means of a winding thread binding together with the set of electrically conductive threads in the warp direction provides the connection in the fabric between the set of electrically conductive threads in the warp direction and the set of electrically conductive threads in the weft direction.

With such tissues a sufficient isotropy of the surface resistivity is obtained when it is measured in different directions. By specific surface resistance of fabrics is meant the electrical resistance that is measured by placing two electrodes on the fabric. The two electrodes are parallel at a distance D from each other. The width of the electrodes is also D, so that a square fabric is enclosed between the electrodes with sides with length D. The length D for the measurements for determining the specific surface resistances shown is 10 cm.

In traditional textile fabrics such as fabrics and knits, the structure and location of the conductive threads results in a very large inherent anisotropy of the surface resistivity as a function of the direction in which it is measured. If the electrodes are positioned so that the shortest distance between the electrodes is directed along the warp or weft threads (when they are conductive), the electrical resistance is much lower than when this shortest distance is at an angle to warp and weft threads (eg an angle of 45 °). However, the fabrics according to the invention have a sufficient degree of isotropy when the surface resistivity is measured in different directions. The objective here is a ratio of the resistivity in the direction of 45 ° with the average of the resistivity in the warp and weft direction of at most 6.

According to the invention, a conductive fabric is obtained which, due to the synergistic combination of its characteristics, contains a number of specific properties: the specific surface resistance of the fabric is isotropic in the warp and weft direction. Preferably, the specific surface resistance in warp direction is at most 10% higher or 10% lower than the specific surface resistance in weft direction. - the anisotropy of the specific surface resistance in other directions is limited (eg when conductivity is measured in other directions, eg in a 45 ° direction and compared with the specific surface resistance in the warp and / or weft direction of the fabric), so that the specific surface resistance of the tissue is sufficiently isotropic. - the conductivity and the isotropy of the conductivity are retained under mechanical stress (including under cyclical mechanical stress) of the fabric (eg under tensile stress in one or more directions), under shear stress, and under bending stress, - the fabric is durable under cyclical stress , while retaining its electrical properties, including isotropy of the electrical conductivity (surface resistivity), - the fabric is easy to drape, so that shapes other than flat shapes can easily be adopted. - The fabric has a textile character.

Preferably, the set of non-conductive warp threads has a density (number of threads per cm) in the warp direction that is at least five times, and preferably ten times, higher than the density (number of threads per cm) of the set of conductive threads in the warp direction.

Preferably, the set of non-conductive warp threads has a density (number of threads per cm) in the weft direction at least five times, and preferably ten times, higher than the density (number of threads per cm) of the set of conductive threads in the weft direction.

Preferably, the electrically conductive wires have a weave less than 5% in the warp direction, more preferably less than 2%.

The binding wires in the warp direction preferably have a weave which is at least 5% (absolute percentage) higher than the weave of the electrically conductive warps in the warp direction.

Preferably, the binding threads in the warp direction have a weave between 2 and 20%; more preferably between 7 and 20%.

Preferably, the non-electrically conductive wires have a weave between 2 and 10% in the warp direction.

Preferably, the non-electrically conductive wires have a weft of between 2 and 10% in the weft direction.

Preferably, the electrically conductive threads have a weft in the weft direction less than 10%, more preferably less than 5%, even more preferably less than 2%.

Tissues with good air permeability can be obtained. The fabric preferably has an air permeability above 1000 liters / (dm 2 min), measuring at a vacuum of 100 Pa and according to BS5636: 1990. More preferably, the air permeability is more than 2000 liters / (dm 2 minute) and, for example, less than 3000 liters / (dm 2 minute).

Conductive fabrics can also be made with a rather low conductivity (eg with a specific surface resistance in the range of 0.1 to 10 Ohm, when measured in warp or weft direction, preferably between 1 and 10 Ohm, more preferably between 5 and 10 Ohm ) and which still have the listed beneficial properties.

The winding thread bond is preferably formed by winding each thread from the set of binding threads relative to one thread from the set of electrically conductive threads in the warp direction, with in each case between one thread from the set of electrically conductive threads in weft direction.

It is a specific object of the invention to provide such fabrics in the range of a surface resistivity of fabrics from 0.1 to 10 ohms (and preferably between 1 and 10 ohms, more preferably between 5 and 10 ohms), when measured in the warp or weft direction of the fabric, because such fabrics are interesting as a heating element, e.g. for heating car seats.

In a preferred embodiment, in the electrically conductive fabric, the set of non-electrically conductive threads in the warp direction and the set of non-electrically conductive threads in the weft direction are connected to each other by means of a classical weave weave (with classical weave weave it is meant that this weave is not a winding thread; for example, it can be used for wading, twill or satin or derivative bindings). Preferably, there are no floating wires over more than two wires.

In a specific embodiment, the connection between the set of electrically conductive threads in the warp direction and the set of non-electrically conductive threads in the weft direction is achieved by a classical weave weave (with classical weave weave it is meant that this weave is not a winding weave weave; become a wad weave, twill weave or satin weave or derived bindings, preferably there are no floating threads over more than two threads.

In a specific embodiment, the connection between the set of non-electrically conductive threads in the warp direction and the set of electrically conductive threads in the weft direction is achieved by a traditional weave weave (such as, for example, lining weave, twill weave or satin weave or derived weaves), preferably there is no floating wires over more than two wires.

In a specific embodiment, the connection between the set of non-electrically conductive threads in the weft direction and the set of warp threads in the warp direction is achieved by a traditional weave weave (such as, for example, lining weave, twill weave or satin weave or derived weaves), preferably there are no floating wires over more than two wires.

These embodiments - each individually or in combination - have the advantage that even better retention of properties - including electrical properties and isotropy of the conductivity and their durability with dynamic mechanical stress, including with bending stress - is achieved with mechanical stress on the fabric.

Preferably the same wires are used for the set of conductive wires in the warp direction as for the set of conductive wires in the weft direction. This gives the advantage that better isotropy values are achieved, especially under mechanical stress on the tissue.

The two non-electrically conductive wire systems preferably contain wires from monofilaments or from multi-filaments or from spun fiber yarns; preferably from polymeric material.

Multifilament yarns of polyester or polyamide, e.g. finer than 200 dtex. Such yarns improve the durability of the fabric.

Use of textured multi-filament yarns for the set of non-electrically conductive threads in weft direction and / or use of textured multi-filament yarns for the set of non-electrically conductive threads in warp direction are advantageous for achieving good air permeability of the electrically conductive fabric.

For the two non-electrically conductive wire systems, thermally stabilized (heat-set) monofilaments or thermally-stabilized (heat-set) multifilament yarns are used.

Thermally stabilized multifilament yarns are preferably used for the threads of the set of binding threads. An example is thermally stabilized (heat set) textured polyester multifilament in the range of 50 - 2000 dtex, for example in the range of 100 - 500 dtex, e.g. 165 dtex. In an embodiment of the invention, the electrically conductive fabric has a specific surface resistance of the fabric between 1 and 10 ohms measured according to the warp direction of the fabric.

In one embodiment of the invention, part of the binding threads of the set of binding threads make a winding thread binding in the S direction, while another part of the binding threads of the set of the binding threads make a winding thread binding in the Z direction upon binding with the same conductive weft thread. Preferably - taken over a unit of width of the fabric (and considered for a conductive weft thread) - the number of binding threads that make a winding thread binding in the S direction is substantially equal to the number of binding threads that make a winding thread binding in the Z direction.

The characterizing feature of this specific embodiment synergistically increases the retention of the isotropy of the electrical conductivity (of the specific surface resistance) of the fabric (in warp and weft direction, but also in other directions) under mechanical stress of the fabric, since the fabric remains even more stable under mechanical loading, because the fabric deforms more evenly.

In one embodiment, the electrically conductive wires in the set of electrically conductive wires in the warp direction and the electrically conductive wires in the set of electrically conductive wires in the weft direction contain metal fibers and / or metal filaments, preferably steel fibers and / or steel filaments, more preferably fibers and / or filaments from stainless steel. Metal monofilaments or metal multifilaments are preferably used because they give a low change in resistance under mechanical stress (e.g. tensile stress on the fabric). However, it is also possible to use spun yarns, e.g. blending yarns from non-conductive fibers (e.g. cotton or polyester) and metal fibers (e.g. from stainless steel).

The use of metal filaments (i.e. with virtually unlimited length) is preferred over the use of metal fibers (these have a certain length). Fibers are spun into yarns. Filaments - alone (monofilament) or combined (twisted, twisted, cabled) into a yarn (or also into a multiple yarn) have the advantage of giving fabrics with better isotropy of the surface resistivity.

Filaments from stainless steel are preferably used. The use of stainless steel multifilaments provides a synergistic increase in durability against cyclical bending stress on the fabric. Multifilaments from stainless steel can be produced, for example, via the technology of bundled drawing. Such multi-filaments have a characterizing hexagonal cross-section.

Metal multi-filaments as conductive threads in warp and weft direction preferably have a twist of at least 40 revolutions per meter; and preferably at most 200 revolutions per meter. Such a twist improves the isotropy of the conductivity of the fabric.

In a preferred embodiment, the electrically conductive threads in chains weft direction are multifilament yarns of stainless steel filaments, e.g. bundled steel fibers. These wires preferably have a twist of at most 200 revolutions per meter; and preferably a twist of at least 40 revolutions per meter. Such a twist improves the isotropy of the conductivity of the fabric.

The use of metal fibers or metal filaments as or in the electrically conductive wires has the additional advantage that the electrically conductive fabric offers good shielding properties against electromagnetic radiation.

In an embodiment of the invention, the coverage of the fabric is higher than 0.5, preferably higher than 0.7. With cover factor is meant the proportion of the area that the yarns of the textile fabric cover relative to the surface that covers the textile fabric. With a covering factor equal to one, the entire surface is covered and there is no space between the threads that form the textile fabric; with a covering factor equal to 0.5, half of the surface is covered by threads and half of the surface is uncovered because there is space between the threads that form the textile fabric. The additional feature of this specific embodiment contributes to and increases the retention of the isotropic electrical conductivity properties of the fabric under mechanical stress.

In a specific embodiment, the electrical resistance of the fabric in the warp direction is at most 10% higher or 10% lower than the electrical resistance in the weft direction.

In a preferred embodiment, the specific surface resistance in the direction that makes an angle of 45 ° with the two electrically conductive wire systems is at most six times the average of the specific surface resistance in the warp and weft direction. And preferably at most five times, more preferably at most three times, and even more preferably at most twice the specific surface resistance in the warp and weft direction.

In a specific embodiment of any embodiment of the invention, the tissue includes electrical contact points through which an electrical current and / or electrical voltage is applied to the tissue.

The electrically conductive fabric provides effective shielding against electromagnetic radiation with a wavelength greater than ten times the size of the meshes between the electrically conductive wires in the fabric. Therefore, the distance between successive electrically conductive wires is preferably at most 3 cm, more preferably at most 1 cm, more preferably at most 6 mm, for suitable shielding against electromagnetic radiation. Such fabrics (with a limited distance between successive conductive wires) have - due to the synergistic effect of this feature - an improved isotropy of the specific surface resistance of the fabric.

The second aspect of the invention is the use of the electrically conductive fabric as a sensor, as a capacity, as a component in electronic components (e.g. textile electronic components) or as an electric heating element.

Fabrics according to the invention can be used, for example, in heating elements, e.g. in clothing applications (coats, underwear, scarves ...), in seat heating in vehicles or in domestic seats, or as a textile electronic component (e.g. in process control in clothing - electrical or electronic textiles, e.g. as a sensor).

Examples of embodiments

In an example of the invention, the fabric comprises the following wire systems: - a set of twisted stainless steel multifilaments in the warp direction (eg multifilaments consisting of 200 bundled stainless steel filaments each with a diameter of 14 microns, twisted together at 200 revolutions in the Z direction), with a density of two wires per centimeter. These threads have a weave of 1% in the fabric. in the warp direction a set of polyester binding threads, e.g. a 480/1 dtex monofilament, with the same density of two threads per centimeter. These threads have a weave of 7% in the fabric. - in a chain direction a set of polyester multifilament threads (e.g. 167/1 dtex), with a density of 14 threads per centimeter. These threads have a weave of 5%. a set of twisted stainless steel multifilaments in the weft direction (e.g. multifilaments consisting of 200 bundled stainless steel multifilaments each with a diameter of 14 microns, twisted together at 200 revolutions in the Z direction), with a density of two wires per centimeter. These threads have a weave of 2%. in the weft direction a set of polyester multifilament threads (e.g. 167/1 dtex), with a density of 14 threads per centimeter. These threads have a weave of 5%.

The sets of polyester multifilament threads in the warp and weft direction make a line winding.

The set of conductive threads in weft direction makes a line winding with the set of polyester multifilament threads in warp direction.

The set of conductive threads in the warp direction and the set of binding threads in the warp direction do not bind with the set of polyester multifilament threads in the weft direction, but one set runs above and the other set below the set of polyester multifilament threads in the weft direction.

Each binding thread forms a winding thread bond with a thread from the set of twisted stainless steel multifilaments in the warp direction, between which one thread of the twisted stainless steel multifilaments is bonded in the weft direction.

The specific surface resistance of this fabric is 0.2 ohm in warp direction, 0.2 ohm in weft direction and in the direction that makes a 45 ° angle with warp and 1 ohm weft.

The air permeability is 1370 l / (dm2.min), which is measured at a vacuum of 100 Pa and according to BS5636: 1990.

This fabric has good bendability (e.g., a small bend radius) and excellent durability with mechanical loading, including in cyclic bending load over 180 °. With mechanical deformation of the tissue, the change in surface resistivity remains limited.

After bending to a bending radius of 1 mm, the surface resistivity of differently tested samples of the fabric was up to 10% higher.

Features of the various embodiments and of the examples can be combined with these combinations falling within the scope of the invention.

Claims (11)

Conclusions An electrically conductive fabric comprising - a set of electrically conductive wires in the warp direction of the fabric, these wires being evenly distributed across the width of the fabric; - a set of electrically conductive wires in the weft direction of the fabric; - a set of non-electrically conductive wires in the warp direction of the fabric; - a set of non-electrically conductive wires in the weft direction of the fabric; - a set of binding threads in the warp direction of the fabric, these binding threads are evenly distributed over the width of the fabric; these wires are preferably non-electrically conductive, and wherein - the density of the set of electrically conductive wires in the warp direction and the density of the set of electrically conductive wires in the weft direction are substantially equal to each other; - the electrically conductive wires have the same electrical conductivity in the warp direction and in the weft direction; - the set of binding threads by means of a winding thread binding together with the set of electrically conductive threads in the warp direction provides the connection in the fabric between the set of electrically conductive threads in the warp direction and the set of electrically conductive threads in the weft direction. The electrically conductive fabric of claim 1, wherein the set of non-electrically conductive threads in the warp direction and the set of non-electrically conductive threads in the weft direction are connected to each other by means of a traditional weave weave, preferably there no floating wires over more than two wires. The electrically conductive fabric as in any of the preceding claims, wherein the specific surface resistance of the fabric is between 0.1 and 10 ohms when measured in the warp direction of the fabric. The electrically conductive fabric of any one of the preceding claims, wherein part of the binding threads of the set of binding threads make a sling thread in the S direction, while another part of the binding threads of the set of the threads are a sling thread binding make in Z direction. The electrically conductive fabric of any of the preceding claims, wherein the electrically conductive threads in the set of electrically conductive threads in the warp direction and the electrically conductive threads in the set of electrically conductive threads in the weft direction metal fibers and / or contain metal filaments. The electrically conductive fabric of claim 5, wherein the electrically conductivity of the electrically conductive wires in the set of electrically conductive wires in the warp direction; and the electrical conductivity of the electrically conductive wires in the set of electrically conductive wires in the weft direction is achieved through the use of metal filaments in these wires. The electrically conductive fabric of any of the preceding claims, wherein the coverage of the fabric is higher than 0.5. The electrically conductive fabric of any of the preceding claims, wherein the specific surface resistance of the fabric in warp direction is at most 10% higher or 10% lower than the specific surface resistance in the weft direction. The electrically conductive fabric as in any of the preceding claims, wherein the specific surface resistivity in the direction that makes an angle of 45 ° with the two electrically conductive wire systems is at most six times the average of the specific resistivity in the warp and the weft direction. The electrically conductive fabric as in any one of the preceding claims, wherein the fabric contains electrical contact points through which an electric current and / or an electric voltage is applied to the fabric. Use of the electrically conductive fabric as in any of the preceding claims, in an electric heating element, and / or for electrostatic shielding, and / or as part of electronic components - for example textile electronic components, and / or as a sensor .