WIRED GLAZING AND A PROCESS FOR MANUFACTURE THEREOF

Abstract

A wired glazing is disclosed comprising a ply of interlayer material, having a first busbar and an auxiliary busbar and heating wires between them. An adhesive layer is arranged between the first busbar and the ply of interlayer material. An auxiliary adhesive layer is arranged where an edge of the auxiliary busbar extends beyond an edge of the first busbar. The auxiliary adhesive layer bonds the auxiliary busbar to the ply of interlayer material. A corresponding process for manufacturing a wired glazing is disclosed.

Claims

1) A glazing, comprising: a ply of interlayer material a first busbar laid over the ply of interlayer material at least one heating wire laid over the first busbar and an auxiliary busbar at least partly laid over the heating wire and at least partly laid over the first busbar wherein a solder layer suitable for melting in an autoclave covers at least part of a surface of the first busbar or the auxiliary busbar and is arranged to contact the heating wire wherein an adhesive layer is arranged between the first busbar and the ply of interlayer material for bonding them together characterised in that: an auxiliary adhesive layer is arranged where an edge of the auxiliary busbar extends beyond an edge of the first busbar for bonding the auxiliary busbar to the ply of interlayer material.

2) A glazing according to claim 1, wherein a distance between the edge of the auxiliary busbar and the edge of the first busbar is in a range 2 mm to 5 mm.

3) A glazing according to claim 1, wherein the first busbar has a width in a range 2 mm to 8 mm.

4) A glazing according to claim 1, wherein the auxiliary busbar has a width in a range 4 mm to 12 mm.

5) A glazing according to claim 1, wherein the first busbar is of metal of thickness in a range 50 um to 200 um.

6) A glazing according to claim 1, wherein the solder layer covers substantially all of a surface of the first busbar in contact with the heating wire or wherein the solder layer covers substantially all of a surface of the auxiliary busbar in contact with the heating wire.

7) A glazing according to claim 1, wherein the solder layer covers both a surface of the first busbar in contact with the heating wire and an opposite surface of the first busbar or wherein the solder layer covers both a surface of the auxiliary busbar in contact with the heating wire and an opposite surface of the auxiliary busbar.

8) A glazing according to claim 1, wherein the solder layer has thickness in a range 1 um to 50 um.

9) A glazing according to claim 1, wherein the solder layer melting point is in a range 120 degrees C. to 150 degrees C.

10) A glazing according to claim 1, wherein the adhesive layer has thickness in a range 10 um to 100 um.

11) A glazing according to claim 1, wherein an array of heating wires extends between, and is in electrical contact with, first and second busbars for supplying electrical power to the array of heating wires.

12) A glazing according to claim 1, wherein the ply of interlayer material is arranged between first and second plies of glazing material.

13) A process for manufacture of a glazing, comprising: providing a ply of interlayer material; laying a first busbar over the ply of interlayer material; laying at least one heating wire over the first busbar; laying an auxiliary busbar at least partly over the heating wire and at least partly over the first busbar; laying a solder layer on at least part of a surface of the first busbar or the auxiliary busbar and arranging the solder layer to contact the heating wire; arranging an adhesive layer between the first busbar and the ply of interlayer material for bonding them together; and arranging an auxiliary adhesive layer where an edge of the auxiliary busbar extends beyond an edge of the first busbar for bonding the auxiliary busbar to the ply of interlayer material.

14) A process for manufacture of a glazing according to claim 13, comprising positioning the edge of the auxiliary busbar and the edge of the first busbar such that the distance between them is in a range 2 mm to 5 mm.

15) A glazing according to claim 1, wherein the first busbar has a width in a range 4 mm to 5 mm.

16) A glazing according to claim 1, wherein the auxiliary busbar has a width in a range 8 mm to 9 mm.

17) A glazing according to claim 1, wherein the first busbar is made of copper with a thickness in a range 90 um to 100 um.

18) A glazing according to claim 1, wherein the solder layer has thickness in a range 5 um to 20 um.

19) A glazing according to claim 1, wherein the solder layer melting point is in a range 125 degrees C. to 135 degrees C.

20) A glazing according to claim 1, wherein the adhesive layer has thickness in a range 20 um to 50 um.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The invention will now be described by means of non-limiting examples with reference to the attached figures.

[0033] FIG. 1 shows a glazing according to the prior art in cross-section, viewed from an end of a first busbar.

[0034] FIG. 2 shows a glazing according to the invention in cross-section, viewed from an end of a first busbar, comprising an auxiliary adhesive layer for bonding an auxiliary busbar to a ply of interlayer material in a region where an edge of the auxiliary busbar extends beyond an edge of the first busbar.

[0035] FIG. 3 shows a glazing according to the invention in a plane containing heating wires (line A-A of FIG. 4).

[0036] FIG. 4 shows a glazing according to the invention in cross-section, viewed from an end of a heating wire (line B-B of FIG. 3).

[0037] FIG. 5 shows a glazing according to a preferred embodiment of the invention, wherein a first busbar and an auxiliary busbar are coated with low melting point solder on all surfaces of the first busbar.

[0038] FIG. 6 shows a glazing according to a preferred embodiment of the invention, wherein a first busbar and an auxiliary busbar are coated with low melting point solder on all surfaces and comprising an auxiliary adhesive layer for bonding an auxiliary busbar to a ply of interlayer material in a region where an edge of the auxiliary busbar extends beyond an edge of the first busbar.

DETAILED DESCRIPTION OF THE INVENTION

[0039] Although the invention is described herein with particular reference to an automotive windscreen, it will be understood that it has applications to other vehicle glazing, for example a rear window or a side window.

[0040] FIG. 1 shows a glazing 1, according to the prior art, wherein a first busbar 21 is laid over the ply of interlayer material 13 and an array of heating wires 41 is laid over the first busbar 21. A low melting point solder layer 51 has been applied on a surface of the first busbar 21 facing the heating wires 41. An auxiliary busbar 22 is laid over the heating wires 41. The interlayer material 13 is arranged on a first ply of glazing material 11, and a second ply of glazing material 12 is laid over the auxiliary busbar 22.

[0041] The low melting point solder layer 51 serves two purposes: firstly of improving an electrical connection between the heating wires and the busbars, and secondly of filling the gaps around the heating wires 41, so as to prevent moisture ingress.

[0042] Between the first busbar 21 and the ply of interlayer material 13 is an adhesive layer 61. The adhesive layer 61 serves the purpose of providing positional stability of the heating wires 41, which is also achievable by firstly embedding the first busbar in the ply of interlayer material 13 and secondly embedding the heating wires 41 in the ply of interlayer material by means of a heated presser roller on a drum of a wire laying apparatus.

[0043] FIG. 2 shows a glazing 1, according to the invention, similar to the glazing 1 of

[0044] FIG. 1, wherein an auxiliary adhesive layer 62 is arranged where an edge of the auxiliary busbar 22 extends beyond an edge of the first busbar 21. The auxiliary adhesive layer 62 bonds the auxiliary busbar 22 to the ply of interlayer material 13, thus providing additional positional stability to the heating wires 41.

[0045] FIG. 3 shows a glazing 1, according to the invention, similar to the glazing 1 of FIG. 2, wherein an auxiliary adhesive layer 62 is arranged where an edge of the auxiliary busbar 22 extends beyond an edge of the first busbar 21. FIG. 3 is a plan view of the plane of the heating wires 41, i.e. line A-A of FIG. 4.

[0046] FIG. 4 is a cross-section of the glazing 1 of FIG. 3, on line B-B.

[0047] FIG. 5 is similar to FIG. 1, but the first busbars 21 is provided with a low melting point solder layer 51 on all surfaces.

[0048] The low melting point solder layer 51 serves two purposes: firstly of improving electrical contact between the heating wires and the busbars 21, 22, and secondly of filling the gaps around the heating wires 41, so as to prevent moisture ingress.

[0049] Optionally an edge of the auxiliary busbar 22 extends beyond an edge of the first busbar 21, so that a heated iron may be used to embed the auxiliary busbar 22 in the interlayer material 13, to fix the auxiliary busbar in position.

[0050] FIG. 6 is similar to FIG. 2, but each of the busbars 21, 22 is provided with a low melting point solder layer 51, 52 on all surfaces.

[0051] In FIGS. 1, 2, 4, 5 and 6, the ply of interlayer material 13 comprises first and second regions of interlayer material 13a, 13b, which have flowed between the original ply of interlayer material 13 and the second ply of glazing material 12, such that the busbars 21, 22 and heating wires 41 are embedded in the ply of interlayer material 13, 13a, 13b. In FIGS. 2 and 6, the second region of interlayer material 13b is bounded by the auxiliary adhesive layer 62. Because the ply of interlayer material 13 comprises a thermoplastic material it flows under elevated temperature and pressure in an autoclave to form first and second regions of interlayer material 13a, 13b.

EXAMPLES OF THE INVENTION

[0052] A glazing was prepared according to the invention in the following process steps. A ply of interlayer material 13, such as polyvinyl butyral (PVB) was provided. The PVB thickness was 0.76 mm. First and second busbars 21, 31 were laid on the ply of interlayer material 13. The busbars comprised copper strip, width 4 mm, thickness 100 um, and a low melting point solder layer 51 substantially covering all of a surface for contacting heating wires 41. The ply of interlayer material 13 was arranged on a drum of a wire laying apparatus known in the art (such as US2009/0206191). Heating wires 41 were laid on the first and second busbars 21, 31, extending between them.

[0053] To simplify a process of manufacture of the busbar, the first busbar 21 was also coated with a low melting point solder layer 51 on an opposite surface to the surface for contacting the heating wires 41. The inventors have found that a first busbar 21 or auxiliary busbar 22 having a low melting point solder layer 51 on both surfaces is suitable for use with the invention. Surprisingly, a result is a reduction in “solder splash” faults compared with the prior art, in which a narrow strip of low melting point solder is applied to a busbar on a surface for contact the heating wires only.

[0054] An adhesive layer 61 was arranged between the first busbar 21 and the ply of interlayer material 13, to bond them together.

[0055] An auxiliary busbar 22 was laid on the array of heating wires 41. An auxiliary adhesive layer 62 was arranged where an edge of the auxiliary busbar 22 extended beyond an edge of the first busbar 21.

[0056] The ply of interlayer material 13 was laid on a ply of glazing material 11. The glazing material was soda-lime silicate float glass. A second ply of glazing material 12 was laid on the auxiliary busbar 22, forming a completed assembly. The completed assembly was pressed at its edges and then de-gassed in a manner known in the art. The assembly was introduced to an autoclave and heated under pressure in a manner known in the art.

[0057] The resultant product was first tested by visual inspection and no “solder splash” faults was observed. The product was further tested using a Salt Spray Test according to International Standard ISO 9227 (similar to DIN 50021, now discontinued). Salt water was sprayed in to a chamber in which the glazing had been placed. Electrical power was supplied to the heating wires 41 via first and second busbars 21, 31 for a period; then electrical power was switched off for a period. The test was repeated over approximately seven weeks. The glazing was observed using a thermal imaging camera. No loss of function due to corrosion by the salt water was observed.