EP2118349B1 - Electrically conductive, elastic compound thread, particularly for rfid textile labels, the use thereof, and the production of a woven fabric, knitted fabric, or meshwork therewith - Google Patents

Abstract

In order to provide an electrically conductive, elastic, textile-processable compound thread (2), and protect the same from breaking under stress, the invention provides that the compound thread (2) has at least one conductor thread (4), a textile tension relief thread (6), and a textile binder thread (8). The compound thread (2) is produced on a knitting or double rib machine using textile binder threads (8), or knitted threads, or on a weaving machine using weft threads and textile binder threads (8). The tension relief thread (6) is disposed at higher tension than the conductor thread (4) and can be stressed using higher tension.

Description

Technical area

The invention relates to an electrically conductive, elastic compound thread, in particular an antenna thread for RFID textile labels. A compound thread is to be understood here as meaning a thread which is composed of different thread elements or fibers. Furthermore, the invention relates to its use and the production of a fabric, knitted or braided with it.

State of the art

It is for example from the WO 2002/071605 it is known to incorporate in a textile material a conductor thread which serves as an antenna for a transponder in a label. Such a conductor consists for example of copper and is incorporated by weaving during the manufacture of the textile material or subsequently applied by embroidery technique on a textile. If now the conductor thread itself should be designed to be elastic, then the known conductor threads are not suitable, since in particular the elasticity of the metal thread is not sufficient to maintain the elasticity of the entire thread.

In the WO 2004/027 132 A1 - as in the priority-based first application DE 102 42 785 A1 in addition - an electrically conductive yarn is disclosed, with an elastic core thread and - at least - an electrically conductive thread wound around the core thread and - at least one wound around the core thread, electrically non-conductive Umwindefaden. The extensibility of the entire, electrically conductive yarn is to be limited by the Umwindefaden. Essential for the yarn of WO 2004/027 132 A1 is here that the elastic core thread gives the yarn an elasticity, while the binding thread ensures that the conductor thread can not break, since the binding thread limits the elasticity of the yarn. However, such a yarn is of limited use in textile applications and does not seem to make sense if a yarn is to be used which does not have to have any rubber-elastic properties. In the WO 2006/128633 as well as in the US 2004/237 494 A1 is also an elastic conductor thread with an elastic core and wound around the elastic core conductor thread disclosed with the same conditions for a meaningful application as in the WO 2004/027 132 A1 ,

In the alien US 4,750,324 A1 (Composite yarn for use in high-temperature area) is disclosed a composite yarn and a composite yarn for processing brittle yarns of ceramics or the like for knitting machines and sewing machines, in which a load-absorbing, flexible core yarn and the brittle yarn are arranged with a flexible twine, that Composite yarn in a curved state with a small radius has a higher tensile strength than the brittle yarn.

The above-mentioned yarns are all afflicted with the disadvantage that they can not be incorporated into a textile fabric in a trouble-free manner and that the electrical function after incorporation into or on a textile material is also not guaranteed to be secure.

Presentation of the invention

The object of the invention is to provide an electrically conductive, elastic compound thread, which can be incorporated as trouble-free as possible in a textile and whose function is guaranteed even after incorporation in or on a textile.

The object is achieved according to the invention by an electrically conductive, textile-processable compound thread according to claim 1. The Zugentlastungsfaden is arranged opposite the conductor thread under higher tensile stress, so that when a strain of the compound initially the strain relief thread is claimed. Furthermore, the strain relief thread is more resilient than the conductor thread. The Zugentlastungsfaden should have an elasticity of 3 to 40% - preferably 5 to 12%. The Compundfaden is with textile binding threads knitted or woven. As a result, the measures of the invention initially have the consequence that is protected by the Zugentlastungsfaden the metal thread or other conductor thread against mechanical overstretching and overstretching, the entire electrically conductive compound thread receives a mechanical strength through the textile binder thread. The strain relief thread should consist of textile materials.

Advantageous embodiments of the electrically conductive, elastic compound thread are described in claims 2 to 15.

It is advantageous according to claim 2, when the conductor thread is arranged such that it can be stretched at least to its proportional limit before the conductor could ever tear. For such strain relief threads for which no proportionality limit can be given, e.g. For Zugentlastungsfäden of certain plastics, it is advantageous if the strain relief thread is arranged so much shorter that the strength load of the conductor thread begins only when the tension of the strain relief thread has reached a size that corresponds to the tensile strength of the conductor (claim 3).

In order to protect the conductor even further, advantageously - as defined in claim 4 - the Zugentlastungsfaden be arranged in relation to the conductor so that the Zugentlastungsfaden can be stretched to its tear limit, before the conductor thread can tear. Advantageously, the conductor thread at the tear limit of Zugentlastungsfaden then still has not reached its tear limit, but there begins to be charged first, or has at most reached its proportionality limit.

It is advantageous if the binding threads - according to claim 5 - set between 15 and 30 times per cm, preferably between 20 and 24 times per cm.

The textile binding threads are - as set forth in claim 6 - preferably made of natural or synthetic fibers.

Under the Zugentlastungsfaden should be understood here either a single thread, possibly consisting of several fibers or a compound of different individual threads. The Zugentlastungsfaden can - for advantageous production - consist of thermally shrinkable material. The strain relief thread may consist of natural fibers or of synthetic fibers, preferably of polyamide, polyester or aramid (claim 8). Also, the conductor may advantageously have a metallic elasticity (claim 9) and of metal or metal alloys, but also of metallic coated, synthetic fibers, preferably made of polyamide, consist (claim 10). But it may also be advantageous if the conductor is a compound having at least one metallic and at least one metallic coated synthetic thread (claim 11). This is advantageous, in particular, if electrical bridging takes place, at least in sections, between the metallic and the metallic coated synthetic thread (claim 12). However, it is also possible to provide a plurality of conductor filaments or conductor fibrils, which then maintain a continuous conductor function upon breakage of one of the conductor filaments by electrical bridge formation (claim 13).

Advantageous is the use of an electrically conductive, elastic, textile compound thread described above as an antenna for RFID textile labels or - more generally - as a conductor in fabrics, knitted fabrics and braids (claim 14).

With such an electrically conductive, elastic, textile compound thread, according to claim 15, a woven, knitted or braided fabric is advantageously produced in a separate process and finally incorporated into a woven fabric, knitted fabric or braid.

The above-mentioned as well as the claimed and described in the following embodiments, according to the invention to be used elements are subject to their size, shape design, material usage and their technical Conception no special exceptions, so that the well-known in the respective field of application selection criteria can apply without restriction.

Brief description of the drawings

Figur 1

einen gewirkten, elektrisch leitenden, elastischen Compoundfaden gemäss einem ersten Ausführungsbeispiel zu der vorliegenden Er- findung;

Figur 2

einen gewebten, elektrisch leitenden, elastischen Compoundfaden gemäss einem zweiten Ausführungsbeispiel zu der vorliegenden Er- findung;

Figur 3

einen Compoundfaden mit Reissfestigkeitsdiagramm.

Exemplary embodiments of the invention will be described in greater detail below with reference to the drawings, in which:

FIG. 1

a knitted, electrically conductive, elastic compound thread according to a first embodiment of the present invention;

FIG. 2

a woven, electrically conductive, elastic compound thread according to a second embodiment of the present invention;

FIG. 3

a compound thread with tear resistance chart.

Ways to carry out the invention

The FIG. 1 shows a Compoundfaden 2 according to a first embodiment of the present invention, in which a loose lying conductive thread 4 and a stretched compared to the latter arranged Zugendlastungsfaden 6 with a binder thread 8 are verwirkt together. In other words, this means that the strain relief 6 is arranged under higher tensile stress than the conductor thread 4. The conductor 4 and the strain relief thread 6 are placed here so that the conductor thread 4 is only claimed at point a + b to train when the Strain relief thread 6 has already reached its rupture limit 62 - at about 28% elongation. The tensile strength of the Zugentlastungsfadens 6 is also greater than that of the conductor thread 4. This corresponds to the case II of the tensile strength diagram of FIG. 3 ,

This compound thread 2 is produced on a knitting or raschel machine. The compound thread has about 22 stitches per cm in this embodiment. The strain relief thread 6 is made of synthetic fibers - here made of polyamide - and has a tensile strength 62 of about 28% based on its Stretching on. The conductive thread 4 is made of metal, in this case of a silver / copper alloy, but may alternatively consist of metallically coated fibers, here of polyamide. According to a further alternative of this first embodiment, a conductor thread 4 made of a metallic thread and a metallic coated thread made of polyamide fibers. In this case, then takes place at least in places, an electrical bridge formation between the metal thread and the metallic coated thread of polyamide fibers by the geometric arrangement. As a result, a higher conductivity of the metal filament can be combined with a breaking strength, which combines the advantages of a metallic filament and a metallic coated filament.

In a second embodiment according to FIG. 2 the compound thread 22 is produced on a weaving machine. In this case, the conductor thread 4 is interwoven as a weft thread with the binding thread 8 and the stretched Zugendlastungsfaden 6 held stretched. Again, all other features and alternatives of the above-described knitted compound thread 2 also apply to the woven compound thread 22.

The FIG. 3 shows in Example II the example of a tear resistance diagram of a compound yarn 2 with two conductor threads 4. It can be seen that the tensile strength 62 and the elasticity 60 of the strain relief thread 6, which in this case consists of Trevira 55 dtex, is substantially greater than the tensile strength 42 and the elasticity 40 of the conductor 4, which consists of an AgCU wire. The strain relief yarn 6 reaches its proportionality limit 60 at about 5% elongation and its tear limit 62 at about 28% elongation at a tensile strength of up to 10 Newton.

In an even looser laying of due to the loose arrangement of the conductor 4, the Compoundfaden can be stretched further up to 40% - the strain relief thread 6 is already torn in this case - until then the conductor thread 4 starts at a + b + c, stretched and at a further extension of 1% reaches its proportional limit 40 and then at one stretch and a tear strength of 0.48 Newton then also breaks. This corresponds to case III in FIG. 3 ,

The advantages of the invention itself but also in the case I according to Figure 3 - or even below - achieved in which the conductor thread 4 is arranged only so much looser than the Zugentlastungsfaden 6, that the conductor thread 4 already at a at the Proportionalitätsgrenze 62 of Strain relief thread 6 begins to be loaded, so that the conductor thread 4 is claimed under an additional load up to its proportional limit 42 and then up to its tear limit 40.

LIST OF REFERENCE NUMBERS

2

knitted compound thread

4

Head thread

6

tension relief

8th

binding thread

22

woven compound thread

40

Proportional limit or flow limit of the conductive thread

42

Rupture limit of the conductive thread

60

Proportional limit of the strain relief thread

62

Rupture limit of the strain relief thread

I

Laying the conductor thread further than the proportional limit of the strain relief thread

II

Laying the conductor thread further than the tear limit of the strain relief thread

III

Laying the ladder thread 40% farther than the strain relief thread, far beyond the tear limit of the strain relief thread

a

Beginning of the strain of the conductor in case I

a + b

Start of strain of the conductor in Case II

a + b + c

Start of strain of the conductor in case III

Claims (15)

1. An electrically conductive, elastic, textile-processable compound thread (2, 12, 22, 32) which has at least one conductor thread (4), one textile tension relief thread (6) and one textile binding thread (8), characterized in that the tension relief thread (6) is arranged under higher tension and has a higher load-bearing capacity than the conductor thread (4), the tension relief thread (6) having an elasticity (60) of 3 to 40%, preferably 5 to 12%, and the compound thread (2) being produced on a knitting or Raschel machine with textile binding threads (8) or stitch threads or on a weaving machine with weft threads and textile binding threads (8).
2. The compound thread as claimed in claim 1, characterized in that the conductor thread (4) is arranged in such a way that, when the proportionality limit (60) of the tension relief thread (6) is reached, the tensile load upon the conductor thread (4) is lower than its breaking limit (40).
3. The compound thread as claimed in claim 1, characterized in that the conductor thread (4) is arranged in such a way that its strength load commences when the tension of the tension relief thread (6) has reached a magnitude which corresponds to the breaking strength (42) of the conductor thread.
4. The compound thread as claimed in claim 1 or 2, characterized in that the conductor thread (4) is arranged in such a way that, when the breaking limit (62) of the tension relief thread (6) is reached, the tensile load upon the conductor thread (4) is lower than its breaking limit (42), preferably also lower than its proportionality limit or yield point (42).
5. The compound thread as claimed in one of claims 1 to 4, characterized in that the textile binding threads (8) bind off up to 30 times per cm, preferably 20 to 24 times per cm.
6. The compound thread as claimed in claim 5, characterized in that the textile binding threads (8) consist of natural or synthetic fibers.
7. The compound thread as claimed in one of claims 1 to 6, characterized in that the tension relief thread (6) consists of thermally shrinkable material.
8. The compound thread as claimed in claims 1 to 6, characterized in that the tension relief thread (6) consists of natural fibers or of synthetic fibers, preferably of polyamide or polyester or aramide.
9. The compound thread as claimed in one of the preceding claims, characterized in that the conductor thread (4) has a metallic elasticity (40) of up to 2%.
10. The compound thread as claimed in claim 9, characterized in that the conductor thread (4) consists of metal or of metal alloys or of metallically coated, synthetic fibers, preferably of polyamide.
11. The compound thread as claimed in one of claims 1 to 9, characterized in that the conductor thread (4) has at least one metallic and at least one metallically coated, synthetic thread.
12. The compound thread as claimed in claim 11, characterized in that electrical bridge formation takes place at least in pieces between the metallic and the metallically coated, synthetic thread.
13. The compound thread as claimed in one of claims 1 to 11, characterized in that at least two conductor threads or conductor fibrils are incorporated in such a way that electrical bridge formation occurs in the event of the break of one of the conductor threads.
14. The use of an electrically conductive, elastic compound thread as claimed in one of claims 1 to 13 as a current conductor in woven fabrics, knitted fabrics and meshworks, in particular as an antenna for RFID textile labels.
15. A method for the production of a woven fabric, knitted fabric or meshwork, characterized in that a compound thread as claimed in one of claims 1 to 13 is produced in a separate process and is finally incorporated into a woven fabric, knitted fabric or meshwork.

Images