Tellurate joining glass having processing temperatures less than or equal to 420° C

Abstract

The present invention relates to a glass, in particular a glass for the joining of glass panes for the production of vacuum insulating glasses at processing temperatures 420 C., to the corresponding composite glass, and to the corresponding glass paste. Moreover, the present invention relates to a vacuum insulating glass produced using the glass paste according to the invention, to the production process thereof, and to the use of the inventive glass and/or composite glass, and glass paste. The glass according to the invention is characterized in that it comprises the following components, in units of mol-%: V.sub.2O.sub.5 5-58 mol-%, TeO.sub.2 40-90 mol-%, and at least one oxide selected from ZnO 38-52 mol-%, or Al.sub.2O.sub.3 1-25 mol %, or MoO.sub.3 1-10 mol-%, or WO.sub.3 1-10 mol-%, or a combination thereof.

Claims

1. A joining glass comprising the following components in units of mol-%: TABLE-US-00007 V.sub.2O.sub.5 5-54 mol-%, TeO.sub.2 40-89 mol-%, and at least one oxide selected from the group consisting of ZnO 38-52 mol-%, Al.sub.2O.sub.3 6-25 mol-%, and a combination thereof.

2. The glass according to claim 1, wherein the glass includes in units of mol-%: TABLE-US-00008 V.sub.2O.sub.5 6-33 mol-%, TeO.sub.2 42-57 mol-%, and at least one oxide selected from the group consisting of ZnO 38-52 mol-%, Al.sub.2O.sub.3 6-25 mol-%, and a combination thereof.

3. The glass according to claim 1, wherein the glass includes in units of mol-%: TABLE-US-00009 V.sub.2O.sub.5 32.7 mol-%, TeO.sub.2 56.3 mol-%, and Al.sub.2O.sub.3 11.0 mol-%.

4. The glass according to claim 1, wherein the glass has a glass transition temperature (Tg) in the range of 260-380 C.

5. The glass according to claim 1, wherein the glass is doped with up to 20 wt % additional Al.sub.2O.sub.3 particles.

6. The glass according to claim 1, wherein the glass is further doped with at least one additional oxide selected from the group consisting of Cr.sub.2O.sub.3, Fe.sub.2O.sub.3, Ga.sub.2O.sub.3 and ZnO, or with additional Al.sub.2O.sub.3 particles doped with said at least one additional oxide.

7. The glass according to claim 5, wherein the average grain size (d50) of Al.sub.2O.sub.3 is 5-90 m.

8. A composite glass comprising a glass according to claim 1 and 1 to 25 wt-% of at least one filling agent selected from the group consisting of zirconyl phosphates, dizirconium diorthophosphates, zirconium tungstates, zirconium vanadates, Zr.sub.2(WO.sub.4)(PO.sub.4).sub.2, aluminum phosphate, cordierite, eucryptite, keatite, (Hf,Zr)(V,P).sub.207, NaZr(PO.sub.4).sub.3 and alkaline earth zirconium phosphate.

9. The composite glass of claim 8, wherein the average grain size (d50) of the filling agent is 5-30 m.

10. A glass paste, comprising the glass of claim 1 and a screen printing medium.

11. A glass paste, comprising the composite glass of claim 8 and a screen printing medium.

12. A vacuum insulating glass comprising the glass of claim 1.

13. A vacuum insulating glass comprising the composite glass of claim 8.

14. An electrical or electronic device comprising the glass of claim 1, wherein the electrical or electronic device is selected from the group consisting of sensors and electro-mechanical systems.

15. An automotive glass or glass paint comprising the glass of claim 1.

16. A vacuum insulating glass comprising at least two glass substrates joined by the glass of claim 1 to define a cavity, wherein said cavity contains at least one solar cell.

17. A process for producing a vacuum insulating glass, comprising: applying the glass paste of onto a glass substrate, drying the paste on the glass substrate for 10 minutes at a temperature of 130 C., firing the glass substrate to a temperature of 300 C. for 30-60 minutes, firing to a joining temperature of 325-390 C. for 1-5 minutes, cooling to room temperature, attaching a second glass substrate, firing to a joining temperature of 325-390 C. for 10-15 minutes and cooling to room temperature.

18. The process of claim 17, wherein the firing is carried out by at least one selected from the group consisting of broadband IR heating, visible light heating, laser light heating, induction heating and microwave heating.

19. The glass according to claim 1, wherein the glass includes in units of mol-%: TABLE-US-00010 V.sub.2O.sub.5 5-37 mol-%, TeO.sub.2 40-70 mol-%, and at least one oxide selected from the group consisting of ZnO 38-52 mol-%, Al.sub.2O.sub.3 6-25 mol-%, and a combination thereof.

20. The glass according to claim 1, wherein the glass includes in units of mol-%: TABLE-US-00011 V.sub.2O.sub.5 5-35 mol-%, TeO.sub.2 40-70 mol-%, and at least one oxide selected from the group consisting of ZnO 38-52 mol-%, Al.sub.2O.sub.3 6-25 mol-%, and a combination thereof.

21. The glass according to claim 1, wherein the glass includes in units of mol-%: TABLE-US-00012 V.sub.2O.sub.5 27.3 mol-%, TeO.sub.2 54.4 mol-%, and Al.sub.2O.sub.3 18.3 mol-%.

22. A joining glass comprising the following components in units of mol-%: TABLE-US-00013 V.sub.2O.sub.5 5-37 mol-%, TeO.sub.2 40-70 mol-%, Al.sub.2O.sub.3 6-25 mol-%, and MoO.sub.3 1-10 mol-%.

23. The glass according to claim 22, wherein the glass includes in units of mol-%: TABLE-US-00014 V.sub.2O.sub.5 5-35 mol-%, TeO.sub.2 40-70 mol-%, Al.sub.2O.sub.3 6-25 mol-%, and MoO.sub.3 1-10 mol-%.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) FIGURE shows the thermal expansion coefficient (TEC) of glass B with content of glass.

(2) The object was met by providing a glass, in particular joining glass, that comprises the following components, in units of mol-%:

(3) TABLE-US-00001 V.sub.2O.sub.5 5-58 mol-%, TeO.sub.2 40-90 mol-%, and at least one oxide selected from ZnO 38-52 mol-%, or Al.sub.2O.sub.3 1-25 mol-%, or MoO.sub.3 1-10 mol-%, or WO.sub.3 1-10 mol-%, or a combination thereof.

(4) Preferably, the glass comprises the following components, in units of mol-%:

(5) TABLE-US-00002 V.sub.2O.sub.5 5-37 mol-%, TeO.sub.2 40-70 mol-%, and at least one oxide, selected from ZnO 38-52 mol-%, or Al.sub.2O.sub.3 6-25 mol-%, or MoO.sub.3 1-10 mol-%, or WO.sub.3 1-10 mol-%, or a combination thereof.

(6) Further the glass comprises preferably the following components, in units of mol-%:

(7) TABLE-US-00003 V.sub.2O.sub.5 5-35 mol-%, TeO.sub.2 40-70 mol-%, and at least one oxide selected from ZnO 38-52 mol-%, or Al.sub.2O.sub.3 6-25 mol-%, or MoO.sub.3 1-10 mol-%, or WO.sub.3 1-10 mol-%, or a combination thereof.

(8) The requirements profile of a joining glass/composite as solder for vacuum insulating glass panes is as follows: Joining temperature 420 C. Thermal expansion coefficient of the composite glass (joining glass+filling agent) in the range of 7.0-8.5 10.sup.6/K Compatibility with standard filling agents: Cordierite (EG0225), beta eukryptite, in the range of 1-25 wt-% Glass starts to soften >300 C. (start of softening >300 C. is required in order to ensure sufficient binder burn out of the glass with standard media.) No crystallization of the glasses in powdered form in the range of 300-420 C. Moisture resistance, low solubility in water Good bonding of the glass on float glass (on both bath side and air side), Compatibility of the glass with standard solvents BDG, DPM Processability when exposed to air Processability by rapid heating ramps and cooling ramps Lead-free, cadmium-free Provision of a hermetic, low-tension glass/glass composite Industrial processing by dispensing, digital printing technique, screen printing, etc. is feasible

(9) Due to the low joining temperature, even thermally pre-tensioned glass panes can be joined without losing their pre-tension. The relatively low joining temperatures also allow coated float glasses to be processed without any damage to the coating (low-E) of the glasses. This makes a simpler design easier, since weight can be saved through the use of thinner panes. Other applications in the field of conductive glass pastes (solar cell applications), as additives for auto glass paints such as silver bus bar hiding, are also conceivable.

(10) Preferably, the glass composition contains a mixture of ZnO and Al.sub.2O.sub.3. However, it is also of advantage if just one component of zinc oxide or aluminum oxide is present:

(11) Accordingly, the following glass composition is preferred:

(12) TABLE-US-00004 V.sub.2O.sub.5 6-33 mol-%, TeO.sub.2 42-57 mol-%, and at least one oxide selected from ZnO 38-52 mol-%, or Al.sub.2O.sub.3 6-25 mol-%, or a combination thereof.

(13) The following glass composition is particularly preferred:

(14) TABLE-US-00005 V.sub.2O.sub.5 32.7 mol-%, TeO.sub.2 56.3 mol-%, and Al.sub.2O.sub.3 11.0 mol-%.

(15) It is also preferred if an amount of 1-10 mol-% of molybdenum oxide and/or tungsten oxide is used aside from V.sub.2O.sub.5 and TeO.sub.2.

(16) The glass preferably has a glass transition temperature (Tg) in the range of 260-380 C.

(17) Moreover, it has also been evident that doping the glass with up to 20 wt-% of aluminum oxide (Al.sub.2O.sub.3) particles, preferably up to 10 wt-%, has an advantageous effect on the further crystal growth of Al-containing crystals in the glass matrix.

(18) Likewise, doping with oxides such as Cr.sub.2O.sub.3, Fe.sub.2O.sub.3, Ga.sub.2O.sub.3 or ZnO, or doping with aluminum oxide (Al.sub.2O.sub.3) particles doped with the oxides specified above has a beneficial effect.

(19) Referring to the doping, it has been evident that it is preferred to use the corundum structure of aluminum oxide. But other modifications of aluminum oxide such as -, -, -, -Al.sub.2O.sub.3 can be used just as well.

(20) The average grain size (d50) of Al.sub.2O.sub.3 is 5-90 m. Preferred ranges are 5-20 m.

(21) In addition to aluminum oxide and the further oxides mentioned above, the use of other materials, such as mullite (3Al.sub.2O.sub.3.2SiO.sub.2), gahnite (ZnO.Al.sub.2O.sub.3) or Al(OH).sub.3 such as boehmite, bayerite, and gibbsite, can be taken into consideration as well.

(22) The glass according to the invention can also comprise a second glass. Although it was mentioned above that it is preferable to use lead-free glasses, in particular for vacuum insulating glasses, lead-containing glasses can well be conceivable as second glass for other applications.

(23) Accordingly, the second glass is another Te-glass or V-glass or Bi-glass or Zn-glass or Ba-glass or alkali-Ti-silicate glass or a lead glass or a combination thereof.

(24) A further aspect of the invention is a composite glass that comprises a filling agent in addition to the glass according to the invention.

(25) The amount of said filling agent is in the range of 1-25 wt-% and it preferably has an average grain size (d50) of 5-30 m. The grain size is preferred to be 10-25 m and most preferred to be 20 m. Mixtures of two or more grain size distributions (coarse: d50=15-25 m and fine: d50=1-10 m) can be used in order to obtain said preferred range.

(26) The filling agent is selected from zirconyl phosphates, dizirconium diorthophosphates, zirconium tungstates, zirconium vanadates, Zr.sub.2(WO.sub.4)(PO.sub.4).sub.2, aluminum phosphate, cordierite, eukryptite, keatite, (Hf,Zr)(V,P).sub.2O.sub.7, NaZr(PO.sub.4).sub.3, alkaline earth zirconium phosphates such as (Mg,Ca,Ba,Sr)Zr.sub.4P.sub.5O.sub.24, either alone or in combination.

(27) A filling agent amount in the range of 20-25 wt-% is preferred.

(28) It should be noted in this context that the thermal expansion coefficient can be controlled in specific manner by means of the added amount of filling agent. This is illustrated in more detail below using exemplary embodiment B.

(29) Moreover, a subject matter of the invention is a glass paste that is produced from the glass according to the invention or the composite glass according to the invention by means of a screen printing medium. Preferably, the glass paste comprises a binding agent. It is preferred to use a polypropylene carbonate for this purpose.

(30) Another subject matter of the invention is a method for the production of a vacuum insulating glass. In the method shown presently, the glass solder according to the invention is used in the form of a paste, although this is shown for exemplary reasons only. Alternatively, the glass solder itself and/or the composite material can be used for the production of a vacuum insulating glass.

(31) The method is characterized by the following steps of: Applying the glass paste according to claims 15-16 onto a glass substrate; drying the paste on the glass substrate for 10 minutes at a temperature of 130 C.; heating the glass substrate to a temperature of 300 C. for 30-60 minutes; firing to a joining temperature of 325-390 C. for 1-5 minutes; cooling to room temperature; applying a second glass substrate; firing to a joining temperature of 325-390 C. for 10-15 minutes; and cooling to room temperature.

(32) The firing can involve various heating processes, such as broadband IR or visible light heating, laser light heating, induction heating or microwave heating.

(33) A further subject matter of the invention is the vacuum insulating glass produced by means of the method described above.

(34) The glass solder according to the invention, the composite glass according to the invention, and the glass paste according to the invention are used as joining material for glass panes for the production of vacuum insulating glasses.

(35) Moreover, as described above, the glass according to the invention and/or the composite glass according to the invention can be added, as admixture, to another basic flow, e.g. a bismuth-containing frit, in order to lower the melting point.

(36) Moreover, the glass solder according to the invention, the composite glass according to the invention, and the glass paste according to the invention can be used as joining material for solar cell applications, such as encapsulating solar cells on the basis of silicon and/or silicon-organic systems and thin layers, encapsulating other electronic devices, such as organic LEDs (OLED), for windows, and as additives for auto glasses and auto glass paints.

(37) The use as a joining material for joining applications for micro-electromechanical systems (MEMS) is also conceivable. Moreover, a use as low temperature joining materials for sensors or a use in thick layer applications, in particular as sintering aid for conductive pastes and as overglaze pastes, is conceivable as well.

(38) The following raw materials can be used for production of the joining glasses: Tellurium oxide powder 75-80% d50=3-10 m Vanadium pentoxide V.sub.2O.sub.5 95-99%: no ammonium vanadate Calcinated aluminum oxide (technical quality) Zinc oxide 99.9% (technical quality) Molybdenum oxide (technical quality) Tungsten oxide (technical quality)

(39) The raw materials are mixed well in a planetary mixer, wing mixer, etc., and are melted in a ceramic crucible made of refractive material on air at 650-750 C. in an electrical furnace.

(40) The low melting temperatures are required in order to prevent evaporation of the TeO.sub.2. An oxidizing melt procedure is required, but no O.sub.2 bubbling.

(41) The quenching can be done in water or, optionally, on water-cooled rollers. The glass has a reddish, brown black color. Due to the low viscosity of the glass, quenching of the glass on a roller is not trivial. In this context, it is recommended to cast at temperatures of approx. 650 C. In order to prevent subsequent re-fusion of the glass, the use of doubly-rotating rollers is recommended.

(42) Subsequently, the quenched frit is ground to grain sizes d9060 m using ball mills, jet mills, etc. The thermal expansion coefficient (TEC) is adjusted, optionally, by adding a ceramic filling agent already during the grinding or in a concluding mixing step.

(43) For glass production, the glass is processed to a paste using a three-roll mill and screen printing medium 801022 or 801026.

(44) Preferably, the glass can be processed using a binding agent made of polypropylene carbonate (e.g. QPac 40 binder, from: Empower Materials, USA). Said binding agent is advantageous in that it decomposes already at temperatures in the range of 250-300 C., which ensures that no carbon residues remain enclosed in the joining glass.

(45) The glasses are then applied onto the glass substrate by means of a dispenser: h=0.3-0.5 mm, b=4-6 mm, and the paste is dried with the float glass for 10 minutes at 130 C.

(46) Ideally, the glass solder-coated float glass pane is heated to a temperature of 300 C. in a furnace and maintained at this temperature for 30-60 minutes, then fired to the joining temperature of 325-390 C., maintained at this temperature for 1-5 minutes, and cooled to room temperature again. In a second process step, the second float glass pane can be placed on the pre-coated float glass pane and can be affixed mechanically by means of clamps. Spacers between the panes provide for a uniform solder height. In the subsequent firing cycle, the composite is heated directly to the joining temperature of 325-390 C. and maintained at this temperature for 10-15 minutes. Finally, the composite is cooled to room temperature again. This procedure ensures that the composite is largely free of pores, since the binding agent was previously burned off at 300 C.

(47) The invention is described in the following on the basis of examples, which do not limit the invention in any form or shape.

Exemplary Embodiments

(48) TABLE-US-00006 TABLE 1 shows the chemical composition and physical properties of the glasses A B C D E F G Composition [mol %] TeO.sub.2 49.3 56.3 54.4 44.2 42.6 60.6 57.5 V.sub.2O.sub.5 11.2 32.7 27.3 10.9 6.7 30.4 36.1 ZnO 39.5 38.6 50.7 Al.sub.2O.sub.3 11.0 18.3 6.3 6.4 WO.sub.3 9 DSC Tg [ C.] 327 298 302 322 373 272 270 Softening point 380 337 334 394 417 311 302 [ C.] TMA-Thermal expansion coefficient 50_250 [10.sup.6/K] 12 12.8 12.1 12.4 12.9 50_200 [10.sup.6/K] 12.3 12.3 11.9 12.1 12.5 14.5 13.5

(49) FIGURE shows that it is feasible to variably adapt the expansion coefficient (TEC) of the glasses. The special feature in this context is that the glasses tolerate high filling agent contents without deterioration of the wetting properties. Whereas the flow properties of high bismuth-containing glasses are clearly reduced already at filling agent contents of 5 wt-%, the glasses described presently allow expansion coefficients of less than 8.10/K to be attained without difficulty without suffering any loss of wettability.

(50) Chemical Resistance in Boiling Water:

(51) 2 g sample, example B (d50 approx. 6 m, d90<50 m) was weighed into a 50-mL volumetric flask, fully deionized water was added to the mark, and this was homogenized. Subsequently, the volumetric flasks were exposed to a temperature of 980.5 C. in a heating bath for 60 min. After cooling, renewed homogenization, topping up to the mark, and a sedimentation period (20 min), the sample was filtered through a 0.45 m filter.

(52) Solubility in water [%]=0.4