Abstract
Coated glass panes having a glass pane and a coating in at least one region of at least one side of the glass pane. The glass pane is composed of glass with SiO.sub.2 and B.sub.2O.sub.3. The coating includes first coating applied in at least one region of the at least one side. The first coating has a binder with SiO.sub.2 and a pigment. The glass pane, in the at least one region, has a flexural strength between at least 5 and at most 170 MPa.
Claims
1. A coated glass pane, comprising: a glass pane having a first side, the glass pane comprising SiO.sub.2 and B.sub.2O.sub.3; and a coating comprising a first coating applied in at least one region of the first side, wherein the first coating comprises a binder comprising SiO.sub.2 and a pigment, wherein the glass pane, in the at least one region, has a flexural strength between at least 5 and at most 170 MPa.
2. The coated glass pane of claim 1, wherein the flexural strength is between at least 20 and at most 170 MPa.
3. The coated glass pane of claim 1, wherein the flexural strength is at least 80 MPa.
4. The coated glass pane of claim 1, wherein the binder is glass-based.
5. The coated glass pane of claim 4, wherein the coating is an enamel layer that further comprises a filler.
6. The coated glass pane of claim 5, wherein the filler has a linear coefficient of thermal expansion between −10*10.sup.−6/K and +10*10.sup.−6/K.
7. The coated glass pane of claim 6, wherein the filler has the linear coefficient of thermal expansion between −6.5*10.sup.−6/K and +3*10.sup.−6/K.
8. The coated glass pane of claim 1, further comprising at least one feature selected from a group consisting of: second coating arranged between the glass pane and the first coating in at least one subregion or within an entirety of the at least one region; the first coating comprises between 0.5% by volume and 50% by volume of pigment; the first coating comprises between 0.5% by volume and 40% by volume of pigment; the first coating comprises between 20% by volume and 40% by volume of pigment; the first coating comprises between 99.5% by volume and 50% by volume of glass frit; the glass pane comprises glass having a linear coefficient of thermal expansion between 2*10.sup.−6/K and 6*10.sup.−6/K; the glass pane comprises at least 60% by weight of SiO.sub.2 to at most 85% by weight of SiO.sub.2; the glass pane comprises at least 7% by weight of B.sub.2O.sub.3 to at most 26% by weight of B.sub.2O.sub.3; the glass pane comprises at least 60% by weight of SiO.sub.2 to at most 85% by weight of SiO.sub.2 and at least 7% by weight of B.sub.2O.sub.3 to at most 26% by weight of B.sub.2O.sub.3; the first coating has a linear coefficient of thermal expansion between at least 3*10.sup.−6/K and at most 10*10.sup.−6/K; the first coating has a linear coefficient of thermal expansion between at least 3*10.sup.−6/K and less than 9*10.sup.−6/K; the glass pane has a thickness between at least 1 mm and at most 12 mm; and any combinations thereof.
9. The coated glass pane of claim 1, wherein the first coating further comprises a blowing agent or a filler.
10. The coated glass pane of claim 1, wherein the binder comprises a glass frit or consists thereof.
11. The coated glass pane of claim 10, wherein the glass frit comprises a coloring constituent.
12. The coated glass pane of claim 10, wherein the pigment in the coating comprises at most 40% by volume.
13. A laminate comprising: the glass pane of claim 1; and a further glass pane, wherein the coating is arranged between the glass pane and the further glass pane.
14. A paste for producing a coating on a glass pane, comprising: at least one binder comprising SiO.sub.2; at least one pigment; and a medium, wherein the binder comprises a glass frit or consists thereof and wherein the glass frit comprises a glass comprising, in % by weight based on oxide: SiO.sub.2 10 to 70; B.sub.2O.sub.3 10 to 26; and Al.sub.2O.sub.3 more than 0 to 9.
15. The paste of claim 14, wherein the at least one binder, the at least one pigment, and the medium have a viscosity, determined by plate viscometer, between 1500 and 8000 mPas.
16. The paste of claim 15, wherein the at viscosity is between 2000 mPas and 6500 mPas.
17. The paste of claim 15, wherein the at viscosity is between 2500 mPas and 5000 mPas.
18. The paste of claim 14, further comprising at least one feature selected from a group consisting of: between 0.5% by volume and 50% by volume of the at least one pigment; between 0.5% by volume and 40% by volume of the at least one pigment; between 99.5% by volume and 50% by volume of the at least one glass frit; the at least one glass frit having a linear coefficient of thermal expansion between at least 2*10.sup.−6/K and at most 10*10.sup.−6/K; the at least one glass frit having a linear coefficient of thermal expansion between at least 3*10.sup.−6/K and at most 8.5*10.sup.−6/K; a blowing agent; a filler; a filler having a linear coefficient of thermal expansion between −10*10.sup.−6/K and +10*10.sup.−6/K; the glass frit having a coloring constituent; a proportion of the at least one pigment of at most 40% by volume; a proportion of the at least one pigment of at most 20% by volume; and any combinations thereof.
Description
BRIEF DESCRIPTION OF THE FIGURES
[0160] The invention is hereinbelow more particularly elucidated with reference to the figures. In the figures:
[0161] FIG. 1 shows a schematic representation (not to scale) of a laminate according to one embodiment;
[0162] FIGS. 2 and 3 show schematic representations (not to scale) of a glass pane according to one embodiment,
[0163] FIG. 4 shows the results of measurements of flexural tensile strength on different glass panes coated according to the present disclosure, wherein the content of the frit and the pigments was varied in each case for the different measurement points,
[0164] FIG. 5 shows the results of flexural tensile strength measurements on different glass panes coated according to the present disclosure, wherein different fillers, namely pyrogenic silica, β-eucryptite and CoralPor® were used for the different measurement points, in each case at a proportion of 1.25% by volume.
[0165] FIG. 6 shows the results of two measurements of flexural tensile strength measurements on different glass panes coated according to the present disclosure, wherein rice starch was used as blowing agent for the first measurement point and sugar was used as blowing agent for the second measurement point, in each case at a proportion of 10% by volume.
[0166] FIGS. 7 to 12 show diagrams relating to the effect of filler and pigment contents in coatings on different coating/pane properties; and
[0167] FIG. 13 shows scanning electron micrographs of different coated glass panes.
DETAILED DESCRIPTION
[0168] FIG. 1 is a schematic representation (not to scale) of a laminate/a laminated glass pane 10 according to one embodiment of the present disclosure. The laminate 10 comprises two panes 1, 2, wherein pane 1 is a glass pane for a vehicle according to one embodiment of the present disclosure. Pane 2 is a further glass pane and may be composed for example of a soda lime glass or else of the presently disclosed glass of pane 1. Arranged between the two glass panes 1, 2 is a polymeric ply 3 and, here in the border region of the laminate 10, the coating 11. Said coating is arranged on one side (not described) of the glass pane 1 and in each case in the context of the description which follows can comprise the first coating or the first coating together with the further coating as an intermediate layer.
[0169] For ease of representation the coating 11 is represented as thick, i.e., comparable in thickness with the two panes 1, 2, but, as mentioned, this is only for ease of representation thereof. The coating 11 is generally markedly thinner than each of the two panes 1 and 2 and generally also thinner than the polymeric ply 3. The polymeric ply 3 may also be a film.
[0170] As is apparent, the laminate 10 is presently in the form of a curved laminated glass pane such as may be used as a windshield for example. However, it is generally also possible, without limitation to the example shown in FIG. 1, for the laminate 10 not to comprise bent panes 1, 2 and to be flat. It is also possible for the curve of the laminate 10 to be precisely opposite to that which is shown FIG. 1. In the example of FIG. 1 glass pane 1 would be the outside of the windshield but it is generally also possible for glass pane 1 to be arranged on the inside of the windshield. However, in any event the coating 3 is arranged between the two glass panes 1, 2.
[0171] However, an arrangement as in FIG. 1 may be advantageous since the glass pane 1 comprises SiO.sub.2 and B.sub.2O.sub.3 as components of the glassy material. Such a borosilicate glass is more scratch resistant than for example a soda lime glass and it may therefore be advantageous when, as shown in FIG. 1, the glass pane 1 is configured in the laminate 10 such that it faces “outwards”, i.e., would face outwards if used as a windshield. This is because this would ensure better protection from stone impacts and similar mechanical stresses.
[0172] To elucidate the construction of the glass pane 1 according to embodiments this is shown in the form of a schematic figure (not to scale) in FIGS. 2 and 3. FIG. 2 shows a side view. The glass pane 1 is not yet bent here. However, it is generally also possible, without limitation to the example of a glass pane 1 shown in FIG. 1, for the glass pane to be bent. However, it may be advantageous to initially use a flat, unbent pane 1 which is then bent later, for example in a thermal process. Here too, the thickness of the coating 11 is shown as markedly greater than in reality for ease of representation.
[0173] The arrangement of the pane 1 corresponds to that shown in FIG. 1, with the exception that the pane in FIG. 2 is not bent. As is apparent, the coating 11 is in this case on the side 102 facing the second pane 2 in the laminate 10. Not shown here is the polymeric ply 3 which is arranged between pane 1 and pane 2 in the laminate. It is expressly noted here that the polymeric ply 3 not only directly contacts side 102 of the pane but is also arranged on the coating 11 arranged in the region (or regions) of pane 1 (i.e., side 102 of pane 1).
[0174] The coating 11 is here arranged in the edge region of pane 1, in the representation of FIG. 2 both on the left-hand and right-hand sides. It may be the case here that the coating is altogether applied in the form of a “border”.
[0175] In this regard reference is made to FIG. 3 which, likewise in schematic form and not to scale, shows a plan view of a pane 1 according to an embodiment. The coating 11 is here in the form of a border running around the edge of the pane 1, wherein the coating is initially opaque, i.e., in the form of a layer without interruptions, and towards the middle of the pane 1 transitions via a matrix or dot pattern 111 into the uncoated region. When using the pane 1 in a laminate 10, this uncoated region is the vision area of a windshield for example. It goes without saying that it is generally possible for the border not to be as uniform as shown schematically in FIG. 3 but rather to comprise, for example, convexities, as is often the case in windshields in the region of the rearview mirror for example.
[0176] FIG. 7 shows a representation of the change in flexural tensile strength relative to a coated substrate without filler for different glass panes coated according to the present disclosure, wherein different fillers, namely a pyrogenic silica, O-eucryptite and CoralPor® were used, in each case at a proportion of 1.25% by volume. Flexural tensile strength was in each case determined by the double ring method according to DIN 1288-5. The respective region of the glass pane subjected to the measurement was in each case coated all over so that uncoated regions of the glass pane had essentially no influence on the measured results. The effect of the proportion of the pigments on flexural tensile strength in particular is readily apparent from this figure.
[0177] FIG. 8 shows the effect of filler content for different fillers on the average fracture modulus (or, synonymously, modulus of rupture, MOR) of the coated glass panes. It is apparent that even an only small addition of only 1.2% by volume result in an improvement, i.e., an increase, in the fracture modulus, compared to coatings comprising no filler, i.e., only glass flux/binder and pigment. It has surprisingly been found that an addition of silica in particular may be particularly advantageous, in particular at relatively high contents of 13% by volume. This is especially surprising compared to a filler such as O-eucryptite which has a particularly low (in fact negative) coefficient of thermal expansion. It would therefore be expected that such a negative-expansion filler such as O-eucryptite should particularly simply contribute to minimizing/adapting to the glass substrate the resulting coefficient of thermal expansion of the coating, in which the pigments which are relatively high-expansion compared to the glass substrate should optimally even be compensated. However, it appears that the positive effect of such special low-expansion fillers or even negative-expansion fillers is surprisingly less than was thought. This also applies accordingly to porous glass spheres such as “CoralPor®” which were also previously regarded as potentially very advantageous for the resulting thermal expansion and, due to their inherent porosity, also for compensating thermally induced stresses.
[0178] FIG. 9 shows the effect of fillers and filler contents on optical density as determined through the pane. It is apparent that filler addition can even improve optical density, in particular when only a small filler amount is added. This could potentially be due to better distribution of the pigment particles in the coating which could be brought about by small amounts of fillers. However, it goes without saying that this is dependent on the type of filler added. However, for most of the fillers investigated and in particular for higher filler contents the addition of filler is associated with a reduction in optical density, though this is still considered sufficient.
[0179] FIG. 10 is a schematic diagram of the effect of pigment and filler content on the resulting average fracture modulus. Higher contents of pigments and higher contents of fillers (wherein the filler used here is a silica) generally also result in higher fracture moduli.
[0180] FIG. 11 shows the effect of the filler content and the pigment content of the coating on optical density for the specimens investigated in respect of the resulting fracture modulus in FIG. 10. It is apparent here that up to filler contents of about 10% by volume the effect on optical density is still acceptably small and the above-described negative effect on optical density occurs only at higher filler contents. At low filler contents optical density even initially increases, as already discussed above, at least for the filler considered here, a silica.
[0181] FIG. 12 should the effects of different pigment and filler contents on the resulting color coordinates of the coating. The effect on the resulting coloring of the coating is very small, so that even in the presently considered “achromatic zone” of color coordinates a* and b* only very small and non-systematic divergences occur. This also applies for quite high filler content of 13% by volume.
[0182] FIG. 13 shows the layer formation for different coatings. The top-left and bottom-left of the figure show two coatings comprising only pigment, at different contents, in addition to the glass flux. The coating shown at the bottom left, which comprises 23% by volume of pigment, shows a smooth, dense coating, while at higher pigment contents a slightly porous layer, which is in particular non-uniform, of up to 4 μm in thickness is formed. Coatings in the middle region of FIG. 13 comprise 23% by volume of pigment and in each case 15% by volume of a filler. While the quartz glass filler (d.sub.50 between 1 and 5 μm) results in very unsettled layer buildup where a low scratch resistance results, if only because individual constituents of the coating protrude, the silicone-based fillers of the “Silres®” coating result in a smooth layer with uniformly distributed pores which are formed by the baking of the organic constituents of the filler. However, the coating has become obviously unstable due to the uniformly distributed pores and is therefore disadvantageous in terms of mechanical layer stability.
[0183] By contrast, a coating as shown at the top-right of FIG. 13 is associated with particularly great advantages. Even at non-binder contents of more than 37% percent by volume (i.e., comparable to the coating at the top-left of FIG. 10 with 35% by volume of pigment) the employed filler, a silica, nevertheless and very surprisingly results in smooth layer formation comparable to a layer having a markedly lower particulate content (such as the coating with 23% by volume of pigment at the bottom-left). However, the filler addition is here associated with a graduated porosity which in particular increases towards the coating-glass pane interface. It is thought by the inventors that it is precisely this gradient of porosity that results in particularly advantageous formation, so that the coating remains sufficiently scratch resistant while nevertheless achieving a high mechanical strength of the coated glass pane.
LIST OF REFERENCE NUMERALS
[0184]
TABLE-US-00024 1 Glass pane 10 laminate, laminated pane 11 Coating 101, 102 Sides of the glass pane 111 Dot matrix 2 Further glass pane 3 Polymeric ply
