Electrolyte conductor, process for manufacturing an electrolyte conductor as well as an electrochemical gas sensor and a gas-measuring device with such a gas sensor

Abstract

An electrolyte conductor (1) has a nonwoven fabric (2), onto which a plastic film (3) is laminated. A process is provided for the manufacture of the electrolyte conductor (1). An electrochemical gas sensor (10) is provided with such an electrolyte conductor (1). A gas-measuring device is provided with such a gas sensor (10).

Claims

1. A process for manufacturing an electrolyte conductor comprising a nonwoven fabric; and a plastic film laminated onto the nonwoven fabric, the process comprising the steps of: providing a first web of nonwoven fabric; providing a second web of plastic film; laying the first web of nonwoven fabric and the second web of plastic film on top of one another; bonding the first web and the second web together to form a composite web by laminating, wherein the second web of plastic film is laminated partially onto only one side of the first web of nonwoven fabric in a pattern, the first web of nonwoven fabric comprising another side located opposite the one side, wherein the another side is free of lamination; and punching or cutting a two-dimensional shape out of the composite web or winding up the composite web to form a roll.

2. A process in accordance with claim 1, wherein a third web of plastic separating film is placed onto the second web of plastic film and the third web of plastic separating film is bonded to the second web of plastic film by laminating.

3. A process in accordance with claim 2, wherein the third web of plastic separating film is removed from the second web of plastic film after the lamination.

4. A process in accordance with claim 1, wherein the lamination is carried out with a roller or with a punch, on which raised sections are arranged in a pattern, wherein no side of the first web of nonwoven fabric is laminated except for the one side of the first web of nonwoven fabric.

5. A process in accordance with claim 1, further comprising: providing an electrochemical gas sensor with the electrolyte conductor, an electrode, an electrolyte reservoir and an electrolyte with the electrolyte conductor forming an electrolyte conduction for conduction of the electrolyte from the electrolyte reservoir in a direction of the electrode in the electrochemical gas sensor.

6. A process in accordance with claim 1, wherein the nonwoven fabric is a glass fiber mat.

7. A process in accordance with claim 1, wherein the nonwoven fabric has a thickness of less than 300 μm.

8. A process in accordance with claim 1, wherein the plastic film has a film thickness of at most 80 μm.

9. A process in accordance with claim 1, wherein the plastic film is a hot-melt adhesive film.

10. A process in accordance with claim 1, wherein a plastic separating film is laminated onto the second web of plastic film, the plastic separating film having a heat resistance that is greater than a heat resistance of the second web of plastic film.

11. A process in accordance with claim 10, wherein the plastic separating film has a film thickness of at most 80 μm.

12. A process in accordance with claim 10, wherein the second web of plastic film has a film thickness of from 30 μm to 50 μm and the plastic separating film has a film thickness of from 30 μm to 50 μm.

13. A process in accordance with claim 10, wherein the plastic separating film consists of polytetrafluoroethylene (PTFE).

14. A process for manufacturing an electrolyte conductor, the process comprising the steps of: providing a first web, the first web comprising a nonwoven fabric; providing a second web, the second web comprising a plastic film; laying the first web and the second web on top of one another; partially laminating the second web onto only a single side of the first web in a pattern to form a composite web after laying the first web and the second web on top of one another, the first web comprising a second side opposite the single side, wherein the second side is not laminated; and punching or cutting a two-dimensional shape out of the composite web or winding up the composite web to form a roll.

15. A process in accordance with claim 14, wherein the nonwoven fabric is a glass fiber mat, wherein no other side of the first web is laminated except for the single side of the first web.

16. A process in accordance with claim 14, wherein the nonwoven fabric has a thickness of less than 300 μm.

17. A process in accordance with claim 14, wherein the plastic film has a film thickness of at most 80 μm.

18. A process in accordance with claim 14, wherein the plastic film is a hot-melt adhesive film.

19. A process in accordance with claim 14, wherein a plastic separating film is laminated onto the second web comprising the plastic film, the plastic separating film having a heat resistance that is higher than a heat resistance of the second web comprising the plastic film.

20. A process in accordance with claim 19, wherein the plastic separating film has a film thickness of at most 80 μm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings:

(2) FIG. 1 is a schematic view of a device for manufacturing an electrolyte conductor;

(3) FIG. 2 is a cross section through an electrochemical gas sensor with an electrolyte conductor; and

(4) FIG. 3 is a top view of an electrochemical gas sensor with an electrolyte conductor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(5) Referring to the drawings, a device for manufacturing an electrolyte conductor 1, which is wound up to form a roll R on a first spool or drum T1 at the output of the device, is seen in a schematic view in FIG. 1.

(6) This first drum T1 pulls down a first web B1 of nonwoven fabric 2 and a second web B2 of plastic film 3 from a second and a third drum T2, T3. The second and third drums T2 and T3 lie behind one another, so that the first web B1 and the second web B2 are pulled approximately parallel and adjacent to one another over a punch support 102.

(7) The first web B1 and the second web B2 are placed on top of one another at the latest during the traveling of a punch 100 in the direction of the punch support 102. In addition, the first web B1 and the second web B2 are bonded with one another to form a composite web VB during the traveling of the punch 100, as a result of which the plastic film 3 is laminated onto the nonwoven fabric 2 on one side. The plastic film 3 is hereby heated at least partially to a temperature above the melting point. Besides a pure pressurization by the punch, this may optionally be carried out by heating the punch 100, ultrasound, heat pulses or high frequency.

(8) In principle, the plastic film 3 can be laminated all over onto the nonwoven fabric 2. In the variant preferred and shown, lamination is, however, carried out in a dot matrix.

(9) For this, the punch 100 has pointed raised sections 101 on the punch surface, which raised sections are arranged in a pattern. These raised sections 101 may have a pyramid-shaped, conical, truncated-pyramid-shaped or frustoconical configuration.

(10) According to the image direction of the enlarged section shown on the bottom right-hand side, the resulting selective penetration of molten plastic film 3 into the nonwoven fabric 2 is seen. In the areas not traversed by plastic, the nonwoven fabric 2 remains hydrophilic and can later ensure the transport of electrolyte. The nonwoven volume susceptible to electrolyte is adjusted by the ratio of laminated to nonlaminated surface.

(11) The first web B1 of nonwoven fabric 2 consists of a glass fiber mat, is binder-free as well as free from plasticizers, silicones and binders. The nonwoven fabric 2 has a nonwoven thickness of less than 300 μm, preferably less than 200 μm, more preferably less than 140 μm, especially preferably less than 80 μm and most preferably less than 50 μm.

(12) Furthermore, the plastic film 3 has a film thickness of at most 80 μm, preferably at most 50 μm and most notably 30 μm to 50 μm. It is resistant to electrolyte and heat as well as free from plasticizers and silicones. It is especially a so-called hot-melt adhesive film, which preferably consists of polyethylene (PE), polyvinyl chloride (PVC) or ethylene vinyl acetate (EVA).

(13) So that the plastic film 3, which lies visibly on the side of the nonwoven fabric 2, which points towards the punch 100, does not remain adhered to the punch 100 or to the raised sections 101, a third web B3, which is parallel to the first and second web B1, B2, is stretched parallel and on the side of the punch 100 over the punch support 102. The third web B3 is hereby pulled from a fourth drum T4 to a fifth drum T5.

(14) During the lamination, first the third web B3, which is a plastic separating film 4, is placed onto the second web B2 of the plastic film 3 due to the traveling of the punch 100. As is seen, the third web B3 of plastic separating film 4 is, however, directly removed again from the plastic film 3 during the removal of the punch 100, i.e., after the lamination (first case). If the tension of the third web B3 is set lower, the first drum T1 and the fifth drum T5, which are arranged adjacent to one another, again remove the third web B3 from the second web B2 (second case). In the first case, the feed rate of the third web B3 may deviate from the feed rate of the first and second web B1, B2, may especially be lower, in order to consume as little plastic separating film 4 as possible. In the second case, the feed rates of all three webs B1, B2 and B3 are selected to be identical (except for shrinkage patterns during bonding).

(15) The plastic separating film 4 has a higher heat resistance than the plastic film 3. As a result of this, a stable intermediate layer is formed on the punch 100, which consequently does not bond with the melting plastic film 3 and also not with the plastic separating film 4. In order to be able to readily exert pressure with the raised sections 101 through the plastic separating film 4 onto the plastic film 3 and onto the nonwoven fabric 2, the plastic separating film 4 shall have a film thickness of at most 80 μm, preferably at most 50 μm and most notably from 30 μm to 50 μm. The plastic separating film 4 preferably consists of polytetrafluoroethylene PTFE.

(16) In an optional variant of the present invention, the plastic separating film 4 may remain as part of the composite web VB. It would then be wound up onto the drum T1 with the composite web VB as electrolyte conductor 1 to form a roll R.

(17) Electrolyte conductors 1 with defined two-dimensional contour may later be cut or punched out of the composite web VB.

(18) Optionally, the cutting out may be carried out between the punch support 102 and the first drum T1. Only the remaining residual web is then wound up to form the roll R.

(19) FIG. 2 shows a cross section through an electrochemical gas sensor 10. FIG. 3 shows a top view of such an electrochemical gas sensor 10.

(20) According to FIGS. 2 and 3, a sensor housing 11 of the gas sensor 10 has an annular outer wall 13 and an annular inner wall 14, so that an annular electrolyte reservoir 12 is formed between the outer wall 13 and the inner wall 14. An electrolyte conductor 1 lies on the reservoir bottom 15 of the electrolyte reservoir 12, especially at least partially annularly around the inner wall 14.

(21) The electrolyte conductor 1 consists of a nonwoven fabric 2, which is laminated onto a plastic film 3 (shown only in FIG. 1). This nonwoven fabric 2 may have one of the optional configuration variants according to the explanations in the general description and concerning FIG. 1. In this case, the plastic film 3 (shown only in FIG. 1) of the electrolyte conductor 1 lies on the reservoir bottom 15 and the nonwoven fabric 2 points away from the reservoir bottom 15. Because of the inherent stiffness of the electrolyte conductor 1 based on the plastic film 3 (shown only in FIG. 1), a fixing on the reservoir bottom 15 is not necessary.

(22) An inner area 16 is formed in the center of the inner wall 14. An electrode 19 (shown only in FIG. 1) is arranged in this inner area 16. A plurality of electrodes may optionally also be arranged in the inner area 16.

(23) The inner wall 14 has a wave-shaped upper edge, over which, however, flow is possible over the entire circumference. For this, a housing cover, not shown, can be arranged spaced apart from the inner wall 14. An electrolyte E will flow over the inner wall 14 on the path from the electrolyte reservoir 12 to the inner area 16 or vice versa, i.e., primarily through the wave valleys in the upper edge.

(24) A second electrolyte conductor 18, which is contacted with the electrolyte conductor 1 in the electrolyte reservoir 12 and protrudes over the inner wall 14 into the inner area 16 in the area of a wave valley of the upper edge, is provided for supporting the transport of the electrolyte E from the electrolyte reservoir 12 to the inner area 16. It is seen that the second electrolyte conductor 18 extends approximately over the entire inner area 16. Space for electrodes is provided under the second electrolyte conductor 18 in the inner area 16 and electrolyte E can collect here. A closed inner area bottom 17 is provided for this (shown only in FIG. 1).

(25) The second electrolyte conductor 18 consists of a nonwoven fabric. The nonwoven fabric is a glass fiber mat, the material thickness of which is between 100 μm and 500 μm. This nonwoven fabric is thus so thick that it is inherently stable and manageable even without plastic film laminated onto it. Optionally, the second electrolyte conductor 18 can be configured directly as an electrode by the nonwoven fabric being bonded with a noble metal, e.g., a noble metal film.

(26) Due to the arrangement, the second electrolyte conductor 18 can remove electrolyte E from the electrolyte conductor 1 at the contact point in the electrolyte reservoir 12 and conduct this electrolyte to the electrode 19 (shown only in FIG. 1) in the inner area 16. For example, sulfuric acid is suitable as electrolyte E.

(27) Thus, the electrolyte conductor 1 in the electrolyte reservoir 12 forms here an electrolyte conduction for an electrolyte E from the electrolyte reservoir 12 in the direction of the electrode 19, namely up to the second electrolyte conductor 18, which takes over the transport of the electrolyte E over the remaining distance up to the electrode 19.

(28) Due to the arrangement of the electrolyte conductor 1 in the electrolyte reservoir 12, the electrode 19 may also be supplied with electrolyte E even in the case of a low filling level in the electrolyte reservoir 12 and also, to a certain extent, independent of position for the electrochemical reaction.

(29) The isolated drops of electrolyte E in the electrolyte reservoir 12 shown as an example are namely absorbed by the nonwoven fabric 2 of the electrolyte conductor 1 and distributed in the volume of the nonwoven fabric 2. If the reservoir bottom 12 is, for example, slanted, the electrolyte E is, as a result, also fed upwards geodetically. Thus, the electrolyte E changes its position at least partially over the distribution in the nonwoven fabric 2 and can again be removed from the nonwoven fabric 2 at another point, namely at the contact to the second electrolyte conductor 18.

(30) The present invention is not limited to one of the described embodiments, but rather can be varied in many ways.

(31) All features and advantages, including design details, spatial arrangements and process steps, appearing from the claims, the description and the drawings may be essential to the present invention both in themselves and in the widest variety of combinations.

(32) While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

LIST OF REFERENCE NUMBERS

(33) 1 Electrolyte conductor 2 Nonwoven fabric 3 Plastic film 4 Plastic separating film 10 Electrochemical gas sensor 11 Sensor housing 12 Electrolyte reservoir 13 Outer wall 14 Inner wall 15 Bottom of reservoir 16 Inner area 17 Bottom of inner area 18 Second electrolyte conductor 19 Electrode 100 Punch 101 Raised section 102 Punch support B1 First web B2 Second web B3 Third web E Electrolyte R Roll T1 First drum T2 Second drum T3 Third drum T4 Fourth drum T5 Fifth drum VB Composite web