Electromagnetic shielding fabric and yarn for its manufacture

Abstract

An assembled yarn comprises a first yarn and a second yarn. The first yarn comprises a core yarn and a first wrap yarn. The core yarn comprises a spun yarn, wherein the spun yarn comprises a blend of fibers, wherein the blend of fibers comprises first electrically conductive fibers. The first wrap yarn comprises or consists out of one or a plurality of metallic filaments. The first wrap yarn is wrapped around the core yarn with at least 300 turns per meter. The second yarn comprises second electrically conductive fibers. The second yarn is wrapped around the first yarn; or the second yarn is ply-twisted with the first yarn thereby forming a plied yarn. The assembled yarn can be used in electromagnetic shielding fabrics.

Claims

1. An assembled yarn comprising a first yarn and a second yarn, wherein the first yarn comprises a core yarn and a first wrap yarn, wherein the core yarn comprises a spun yarn, wherein the spun yarn comprises a blend of fibers, wherein the blend of fibers comprises first electrically conductive fibers, wherein the first wrap yarn comprises one or a plurality of metallic filaments, and wherein the first wrap yarn is wrapped around the core yarn with at least 300 turns per meter, wherein the second yarn comprises a spun yarn from a blend of fibers, wherein the blend of fibers comprises second electrically conductive fibers, and wherein the second electrically conductive fibers are stainless steel fibers, and wherein the second yarn is either wrapped around the first yarn; or ply-twisted with the first yarn thereby forming a plied yarn.

2. The assembled yarn according to claim 1, wherein the one or the plurality of metallic filaments comprises a stainless steel filament a silver plated copper filament, a silver filament, a metal plated copper filament, or a metal plated steel filament.

3. The assembled yarn according to claim 1, wherein the first conductive fibers are stainless steel fibers.

4. The assembled yarn according to claim 1, wherein the second yarn is wrapped around the first yarn, wherein the first wrap yarn is wrapped in a first direction around the core yarn, and wherein the second yarn is wrapped around the first yarn in the direction opposite to the first direction.

5. The assembled yarn according to claim 1, wherein the fibers of the spun yarn of the core yarn are twisted in a first direction, wherein the first wrap yarn is wrapped in a first direction around the core yarn, wherein the second yarn is a spun yarn having fibers that are twisted in the first direction, and wherein the second yarn is wrapped around the first yarn in the opposite direction to the first direction.

6. An electromagnetic shielding fabric comprising the assembled yarn according to claim 1, wherein the electromagnetic shielding fabric is a knitted fabric.

7. An electromagnetic shielding fabric comprising electrically conductive yarns in a warp direction and in a weft direction of the electromagnetic shielding fabric, wherein the electromagnetic shielding fabric is a woven fabric, and wherein the warp direction or the weft direction or the warp direction and the weft direction comprise the assembled yarn according to claim 1 as an electrically conductive yarn.

8. The electromagnetic shielding fabric according to claim 7, wherein the electromagnetic shielding fabric comprises the assembled yarn as electrically conductive yarn in the warp direction and the weft direction, wherein the warp direction comprises a second type of warp yarns and wherein the weft direction comprises a second type of weft yarns, wherein, in the warp direction, one or more than one second type of warp yarns alternates with one or more than one assembled yarn, and wherein, in the weft direction, one or more than one second type of weft yarns alternates with one or more than one assembled yarns.

9. The electromagnetic shielding fabric according to claim 7, wherein the woven fabric comprises, in the warp direction and/or in the weft direction, a first set of the assembled yarn and a second set of the assembled yarn, wherein, in the first set of the assembled yarn, the first wrap yarn comprises one or a plurality of stainless steel filaments, wherein, in the second set of the assembled yarn, the first wrap yarn comprises one or a plurality of metal plated copper filaments, and wherein, in the warp and/-or in the weft direction of the woven fabric, yarns of the first set of assembled yarn alternate according to a pattern with yarns of the second set of assembled yarn.

10. An apparel product comprising the electromagnetic shielding fabric according to claim 6.

11. The apparel product according to claim 10, wherein the electromagnetic shielding fabric has a first side that provides an outer side of the apparel product, and wherein the electromagnetic shielding fabric has a second side that provides an inner side of the apparel product.

12. An apparel product comprising at least two panels of an electromagnetic shielding fabric comprising electrically conductive yarns in a warp direction and in a weft direction of the electromagnetic shielding fabric, wherein the electromagnetic shielding fabric is a woven fabric, wherein the warp direction or the weft direction or the warp direction and the weft direction comprise the assembled yarn according to claim 1 as an electrically conductive yarn, wherein the apparel product comprises a stitching yarn, wherein the at least two panels of the electromagnetic shielding fabric are stitched together by means of the stitching yarn, and wherein the stitching yarn comprises electrically conductive fibers.

13. A sensor comprising the assembled yarn according to claim 1.

14. A textile heating product comprising the assembled yarn according to claim 1, wherein, when the textile heating product is in use, heat is generated by the Joule effect in the assembled yarn.

Description

MODE(S) FOR CARRYING OUT THE INVENTION

(1) An exemplary fabric according to the second aspect of the invention has been made. The fabric comprises in weft and in warp direction the same assembled yarn according to the first aspect of the invention. The assembled yarn comprises a core yarn which is a spun yarn of count Nm50/1 (20 tex) out of an intimate blend of polyester fibers (70% by weight) and stainless steel fibers (30% by weight); the core yarn is twisted in Z-direction. The core yarn is wrapped with a 40 μm diameter silver plated copper filament as first wrap yarn. Alternatively, a 50 μm diameter (or a 30 μm diameter) stainless steel fiber filament can be used as first wrap yarn. The metallic filament is e.g. wrapped in Z-direction with 1000 turns per meter around the core yarn. The second yarn is a spun yarn of count Nm 50/1 (20 tex) out of an intimate blend of polyester fibers (70% by weight) and stainless steel fibers (30% by weight). The second yarn is twisted in Z-direction. The second wrap is wrapped in S-direction with 1000 turns per meter around the combination of the core yarn and the first wrap yarn. The fabric construction is a 2/1 twill weave. In an example, the fabric was woven consisting out of 25 assembled yarns in weft per centimeter and 31 assembled yarns per centimeter in warp direction, the weight of the fabric was approximately 300 g/m.sup.2.

(2) In another example, the core yarn comprises meta-aramid fibers in addition to or replacing the polyester fibers of the first example; and the second wrap comprises meta-aramid fibers in addition to or replacing the polyester fibers of the first example.

(3) An example of the invention is a woven fabric for use in protective clothing, e.g. for workwear for workers working at high voltage electricity lines. The fabric comprises an assembled yarn in the warp direction and in the weft direction. The assembled yarn comprises a first yarn and a second yarn. The first yarn comprises a core yarn and a first wrap yarn. The core yarn is a Nm 40/1 (25 tex) blended spun yarn comprising 70% by weight meta-aramid fibers, 5% by weight para-aramid fibers and 25% by weight stainless steel fibers. The first wrap yarn consists out of one silver-coated copper filament of 40 pm diameter, wrapped around the core yarn with 1000 turns per meter. The second yarn is a Nm 40/1 (25 tex) blended spun yarn comprising 70% by weight meta-aramid fibers, 5% by weight para-aramid fibers and 25% by weight stainless steel fibers. In a first example, the second yarn is wrapped around the first yarn, with at least 300 turns per meter. In a second example, the second yarn is ply-twisted, with 300 turns per meter, with the first yarn thereby forming a plied yarn. In an example, the fabric was woven consisting out of 22 assembled yarns per centimetre in the weft and 27 assembled yarns per centimetre in warp direction, the weight of the fabric was approximately 315 g/m.sup.2.

(4) In another example, a fabric was woven with 22 weft yarns per centimetre and with 27 warp yarns per centimetre, in weft direction 2 assembled yarns were alternated with 1 blended yarn and in warp direction 1 assembled yarn was alternated with 2 blended yarns as described in this paragraph, the weight of the fabric was approximately 280 g/m.sup.2.

(5) An example of the invention is a woven fabric for use in protective clothing, e.g. for workwear for workers working at high voltage electricity lines. The fabric comprises an assembled yarn in the warp direction and in the weft direction. The assembled yarn comprises a first yarn and a second yarn. The first yarn comprises a core yarn and a first wrap yarn. The core yarn is a Nm 50/1 (20 tex) blended spun yarn comprising 65% by weight meta-aramid fibers, 5% by weight para-aramid fibers and 30% by weight stainless steel fibers. The first wrap yarn consists out of one silver plated copper filament of 40 μm diameter, wrapped around the core yarn with 1000 turns per meter. The second yarn is a Nm 50/1 (20 tex) blended spun yarn comprising 65% by weight meta-aramid fibers, 5% by weight para-aramid fibers and 30% by weight stainless steel fibers. In a first example, the second yarn is wrapped around the first yarn, with at least 1000 turns per meter. In a second example, the second yarn is ply-twisted, with 600 turns per meter, with the first yarn thereby forming a plied yarn. In an example, the fabric was woven consisting out of 20 assembled yarns in weft per centimetre and 20 assembled yarns per centimetre in warp direction, the weight of the fabric was 250 g/m.sup.2.

(6) The woven fabric can be made consisting in weft and in warp direction out of the assembled yarns of the previous paragraphs. It is also possible to position in weft and in warp direction in between two consecutive assembled yarns other yarns; e.g. Nm 50/2 (20*2 tex) blended yarns consisting out of an intimate blend of 65% by weight meta-aramid fibers, 5% by weight para-aramid fibers and 30% by weight stainless steel fibers, and having 600 turns per meter ply twist. E.g. 1, 2, 3 or more of such yarns can be provided between each two consecutive assembled yarns. In an example, a fabric was woven with 20 weft yarns per centimetre and with 20 warp yarns per centimetre, in each direction assembled yarns and blended yarns as described in this paragraph were alternated.

(7) Several weaves of the fabric are possible, e.g. plain weave, twill weaves, satin weave, ripstop weaves, chevron twill weaves. Preferred is a reinforced twill weave.

(8) The electromagnetic shielding fabrics of the invention show excellent electrical conductivity, even after laundry. The electrical conductivity of an inventive fabric has been measured between two electrodes that make a point contact with the fabric. After 10 laundry cycles, the electrical resistance of the fabric is below 0.7 Ohm per meter distance between the point electrodes, in warp direction, in weft direction and in the direction making a 45° angle with the warp and with the weft direction. After 20 laundry cycles, the electrical resistance of the fabric was still below 1.2 Ohm per meter distance between the point electrodes in each of the three test direction.

(9) The electromagnetic shielding fabric according to the invention showed excellent electromagnetic shielding results in a broad range of frequencies.