Low-temperature tellurite glass mixtures for vacuum compaction at temperatures of 450 degrees C or less

Abstract

The present invention relates to a glass, in particular a glass for joining glass panes in order to produce vacuum insulated glasses at processing temperatures of 450 C., to the corresponding composite glass, and to the corresponding glass paste. The present invention further relates to a vacuum insulated glass produced by means of the glass paste according to the invention, to the production process thereof, and to the use of the glass according to the invention or of the composite glass and of the glass paste. The glass according to the invention is characterized in that said glass comprises the following components in wt %: TeO.sub.2V.sub.2O.sub.5 glass in the range of 60-100 wt %, high temperature glasses, selected from the group consisting of lead glass, bismuth glass, zinc glass, barium glass, calcium glass, alkali silicate glass, in the range of 0-20 wt %, and reactive oxides, selected from the group consisting of Al.sub.2O.sub.3, Y.sub.2O.sub.3, La.sub.2O.sub.3, ZnO, Bi.sub.2O.sub.3, SiO.sub.2, ZrO.sub.2, zircon, Nb.sub.2O.sub.5, V.sub.2O.sub.5, TeO.sub.2, CeO.sub.2, SnO, SnO.sub.2, FeO, MnO, Cr.sub.2O.sub.3, CoO, oxide pigments, or a combination thereof, in the range of 0-20 wt %.

Claims

1. A joining glass composition comprising: 60-99 wt % of a TeO.sub.2V.sub.2O.sub.5 glass, 0.5-20 wt % of a high-temperature glass selected from the group consisting of lead glass, bismuth glass including 75-85 wt % Bi.sub.2O.sub.3, 8-15 wt % ZnO, 5-12 wt % B.sub.2O.sub.3, calcium glass, alkali silicate glass, and combinations thereof, and 0.5-20 wt % of a reactive oxide selected from the group consisting of Y.sub.2O.sub.3, La.sub.2O.sub.3, Bi.sub.2O.sub.3, SiO.sub.2, ZrO.sub.2, zircon, Nb.sub.2O.sub.5, and combinations thereof.

2. The joining glass composition according to claim 1, wherein the TeO.sub.2V.sub.2O.sub.5 glass comprises 40-61 wt % TeO.sub.2, 9-40 wt % V.sub.2O.sub.5, and 5-20 wt % Al.sub.2O.sub.3.

3. The joining glass composition according to claim 2, wherein the TeO.sub.2V.sub.2O.sub.5 glass comprises 50-61 wt % TeO.sub.2, 20-35 wt % V.sub.2O.sub.5, and 10-20 wt % Al.sub.2O.sub.3.

4. The joining glass composition according to claim 1, wherein the high-temperature glass comprises the bismuth glass.

5. The joining glass composition according to claim 1, further comprising a filler in the range of 1-25 wt % with respect to a total combined amount of the TeO.sub.2V.sub.2O.sub.5 glass, the high-temperature glass, and the reactive oxide.

6. The joining glass composition according to claim 5, wherein the filler comprises cordierite, eucryptite, or a combination thereof.

7. The joining glass composition according to claim 1, further comprising a binder and a solvent.

8. A method of producing a vacuum insulated glass comprising: applying a glass composition according to claim 1 onto a first glass substrate, heating the glass composition and the first glass substrate to a temperature of 130 C. for 10 minutes, heating the glass composition and the first glass substrate to a temperature of 300 C. for 30-60 minutes, heating the glass composition and the first glass substrate to a joining temperature of 325-390 C. for 1-5 minutes, cooling the glass composition and the first glass substrate to room temperature, bringing a second glass substrate into contact with the glass composition and, heating the glass composition, the first glass substrate and the second glass substrate to the joining temperature of 325-390 C. for 10-15 minutes, and evacuating a gap between the first glass substrate and the second glass substrate while cooling the glass composition, the first glass substrate and the second glass substrate to room temperature.

9. The method according to claim 8, wherein the TeO.sub.2V.sub.2O.sub.5 glass comprises 40-61 wt % TeO.sub.2, 9-40 wt % V.sub.2O.sub.5, and 5-20 wt % Al.sub.2O.sub.3.

10. The method according to claim 9, the TeO.sub.2V.sub.2O.sub.5 glass comprises 50-61 wt % TeO.sub.2, 20-35 wt % V.sub.2O.sub.5, and 10-20 wt % Al.sub.2O.sub.3.

11. The method according to claim 8, wherein the glass composition further comprises a filler in the range of 1-25 wt % with respect to a total combined amount of the TeO.sub.2V.sub.2O.sub.5 glass, the high-temperature glass, and the reactive oxide.

12. The method according to claim 11, wherein the filler comprises cordierite, eucryptite, or a combination thereof.

13. The method according to claim 8, wherein a binder and a solvent are added to the glass composition to make a paste, and the paste, including the glass composition, is applied to the first glass substrate.

14. The method according to claim 8, wherein process steps are performed at a pressure that is below atmospheric pressure.

15. A glass paste comprising: a composite glass including: a) 75-99 wt % of a joining glass including: i. 60-99 wt % of a TeO.sub.2V.sub.2O.sub.5 glass; ii. 0.5-20 wt % of a high-temperature glass selected from the group consisting of lead glass, bismuth glass including 75-85 wt % Bi.sub.2O.sub.3, 8-15 wt % ZnO, 5-12 wt % B.sub.2O.sub.3, calcium glass, alkali silicate glass, and combinations thereof; iii. 0.5-20 wt % of a reactive oxide selected from the group consisting of Y.sub.2O.sub.3, La.sub.2O.sub.3, Bi.sub.2O.sub.3, SiO.sub.2, ZrO.sub.2, zircon, Nb.sub.2O.sub.5, and combinations thereof; and b) 1-25 wt % of a filler; and a screen printing medium including a binder and a solvent.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIGURE shows the dependence of the ball point temperature on the volume concentration of the additive.

DETAILED DESCRIPTION OF THE INVENTION

(2) The invention provides several options to control the viscosity: a) providing a TeO.sub.2V.sub.2O.sub.5 glass and b) addition of high temperature glasses or c) addition of reactive fillers, mainly oxide-based, which are added to the joining mixture or d) combinations of a) with b) and c).

(3) The above object has been achieved by providing a glass, in particular joining glass, which comprises the following components in wt %: TeO.sub.2V.sub.2O.sub.5 glass in the range of 60-100 wt %, high-temperature glasses selected from the group consisting of lead glass, bismuth glass, zinc glass, barium glass, calcium glass, alkali silicate glass, in the range of 0-20 wt %, and reactive oxides, selected from the group consisting of Al.sub.2O.sub.3, Y.sub.2O.sub.3, La.sub.2O.sub.3, ZnO, Bi.sub.2O.sub.3, SiO.sub.2, ZrO.sub.2, zircon, Nb.sub.2O.sub.5, V.sub.2O.sub.5, TeO.sub.2, CeO.sub.2, SnO, SnO.sub.2, FeO, MnO, Cr.sub.2O.sub.3, CoO, oxide pigments, or a combination thereof, in the range of 0-20 wt %.

(4) A preferred embodiment is when TeO.sub.2V.sub.2O.sub.5 glass, high temperature glasses and reactive oxides are used: TeO.sub.2V.sub.2O.sub.5 glass in the range of 60-100 wt %, high-temperature glasses selected from the group consisting of lead glass, bismuth glass, zinc glass, barium glass, calcium glass, alkali silicate glass, in the range of 0.5-20 wt %, and reactive oxides, selected from the group consisting of Al.sub.2O.sub.3, Y.sub.2O.sub.3, La.sub.2O.sub.3, ZnO, Bi.sub.2O.sub.3, SiO.sub.2, ZrO.sub.2, zircon, Nb.sub.2O.sub.5, V.sub.2O.sub.5, TeO.sub.2, CeO.sub.2, SnO, SnO.sub.2, FeO, MnO, Cr.sub.2O.sub.3, CoO, oxide pigments, or a combination thereof, in the range of 0.5-20 wt %.

(5) The requirement profile of a joining glass/composite as a solder for vacuum insulated glass panes is as follows: joining temperature 400 C. thermal expansion coefficient of the composite glass (joining glass+filler) between 7.5-910.sup.6/K compatibility with standard fillers: cordierite, beta-eucryptite between 1-25 wt % Begin of softening of the glass >300 C. (softening beginning >300 C. is necessary to ensure sufficient binder burnout of the glass with standard media.) no crystallization of the glasses in powder form between 300-420 C. moisture resistance, low water solubility good bonding of the glass to float glass (both on the bath side and on the air side) compatibility of the glass with standard solvents BDG, DPM processing in air possibility of processing by fast heating ramps and cooling ramps lead free, cadmium free ensuring a hermetic, low stress glass/glass composite possibility of industrial processing by means of dispensing, digital printing technology, screen printing etc.

(6) Due to the low joining temperature, thermally toughened glass panes can also be joined without losing their preload. In addition, due to the relatively low joining temperatures, it is possible to process coated float glasses without damaging the coating (low-E) of the glasses. This facilitates a simpler structure, since the use of thinner panes weight can be saved. Other applications in the field of conductive glass pastes (solar cell applications), as additives for automotive glass paints, are also conceivable.

(7) The TeO.sub.2V.sub.2O.sub.5 glass consists preferably of

(8) TABLE-US-00001 TeO.sub.2 40-61 wt %, V.sub.2O.sub.5 9-40 wt %, Al.sub.2O.sub.3 5-20 wt %.

(9) A preferred range is

(10) TABLE-US-00002 TeO.sub.2 50-61 wt %, V.sub.2O.sub.5 20-35 wt %, Al.sub.2O.sub.3 10-20 wt %.

(11) Very particularly preferred is the use of the following glass:

(12) TABLE-US-00003 TeO.sub.2 56.00 wt %, V.sub.2O.sub.5 32.00 wt %, Al.sub.2O.sub.3 12.00 wt %.

(13) The high-temperature glass preferably consists of bismuth glass, with

(14) TABLE-US-00004 Bi.sub.2O.sub.3 in the range of 75-85 wt %, ZnO in the range of 9-15 wt %, and B.sub.2O.sub.3 in the range of 5-12 wt %.

(15) The reactive oxides are preferably selected from the group consisting of Al.sub.2O.sub.3, Y.sub.2O.sub.3, La.sub.2O.sub.3, ZnO, Bi.sub.2O.sub.3, SiO.sub.2, ZrO.sub.2, zircon, Nb.sub.2O.sub.5, or combinations thereof. Most preferably, the reactive oxides are selected from the group consisting of Al.sub.2O.sub.3, Y.sub.2O.sub.3, Bi.sub.2O.sub.3, ZnO, or combinations thereof.

(16) Another aspect of the invention is a composite glass, further comprising a filler in addition to the glass according to the invention.

(17) This filler is in the range of 1 to 25 wt % and is selected from cordierite or eucryptite. Preferred is a filler range of 20-25 wt %.

(18) Another subject of the invention is a glass paste which is produced from the glass according to the invention or from the composite glass according to the invention by means of a screen printing medium. It is preferred that the glass paste comprises a binder. Here, preferably a polypropylene carbonate is used.

(19) Another subject of the invention is a process for producing a vacuum insulated glass. In the process shown herein, the glass solder according to the invention is used in the form of a paste, which is, however, only illustrated by way of example. Alternatively, the glass solder itself or the composite material can also be used to produce a vacuum insulated glass.

(20) The process is characterized by the following steps: applying the glass paste according to claims 8-9 onto a glass substrate, drying the paste on the glass substrate for 10 minutes at 130 C., heating the glass substrate to a temperature of 300 C. for 30-60 minutes, heating to a joining temperature of 325-390 C. for 1-5 minutes, cooling to room temperature, attaching a second glass substrate, heating to a joining temperature of 325-390 C. for 10-15 minutes, and evacuating the glass/glass composite while cooling to room temperature.

(21) Another subject of the invention is the vacuum insulated glass, which was produced by the process described above.

(22) 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 insulated glasses.

(23) In addition, uses as joining material for solar cell applications and as additives for automotive glass paints are also contemplated.

(24) The following raw materials can be used for the production of the joining glasses: tellurium oxide powder 75-80% d50=3-10 m vanadium pentoxide V.sub.2O.sub.5 95-99% calcined alumina

(25) The raw materials are well mixed in a planetary mixer, paddle mixer, etc. and melted in a ceramic crucible, refractory material under air at 650-750 C. in an electric furnace.

(26) The low melting temperatures are necessary to prevent evaporation of the TeO.sub.2. Melting under oxidizing conditions is necessary but no O.sub.2 bubbling. Quenching may be in water or optionally on water-cooled rollers. The glass has a reddish, brown black color. Quenching the glass on a roller is not trivial due to the low viscosity of the glass. Here a casting is recommended at temperatures of about 650 C. In order to prevent the subsequent re-melting of the glass with each other, the use of double-rotating rollers is recommended.

(27) Subsequently, the quenched frit is ground to particle sizes d9060 m in ball mills, jet mills, etc. Optionally, the CTE is set either during grinding by adding a ceramic filler or in a final mixing step.

(28) For the production of the glass, the glass is processed with a screen printing medium 801022 or 801026 via a three-roll mill to form a paste.

(29) Preferably, the glass may be processed with a binder of polypropylene carbonate (e.g. QPac 40 binder, company: Empower materials, USA). This binder has the advantage that it decomposes at temperatures as low as 250-300 C. and thus ensures that no carbon residues remain trapped in the joining glass.

(30) The glasses are then applied to 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. Ideally, the glass solder-coated float glass is heated in an oven with electrically heated infrared elements to a temperature of 300 C. and held at this temperature for 30-60 minutes, then heated to the joining temperature of 325-390 C., held for 1-5 minutes, and cooled to room temperature. In a second process step, the second float glass pane can be placed on the pre-coated float glass pane and mechanically fixed by means of clamping. Spacers between the panes ensure a uniform soldering height.

(31) In the following firing cycle, the composite is heated directly to the joining temperature of 325-390 C. and held at this temperature for 10-15 minutes. Finally, the composite is cooled again to room temperature. This process ensures that the composite is largely free of pores, since the binder has been burned out at 300 C. Individual process steps are carried out at reduced atmospheric pressure such as light vacuum (about 100-600 mbar), medium vacuum (about 0.1-100 mbar) and high vacuum (<0.01 mbar) to control pore formation.

(32) The invention will now be described by way of examples, which do not limit the invention.

Exemplary Embodiments

(33) High-temperature glasses selected from the group consisting of lead glass, bismuth glass, zinc glass, barium glass, calcium glass, alkali silicate glass in the range of 0.5-20 wt %, were added to the joining glass mixtures from PCT/EP2015/072207. Here, an advantageous effect at joining conditions in a vacuum was observed.

(34) Furthermore, reactive oxides selected from the group consisting of Al.sub.2O.sub.3, Y.sub.2O.sub.3, La.sub.2O.sub.3, ZnO, Bi.sub.2O.sub.3, SiO.sub.2, ZrO.sub.2, zircon, Nb.sub.2O.sub.5, V.sub.2O.sub.5, TeO.sub.2, CeO.sub.2, SnO, SnO.sub.2, FeO, MnO, Cr.sub.2O.sub.3, CoO, oxide pigments, or a combination thereof, in the range of 0.5-20 wt %, were added to the joining glass mixtures from PCT/EP2015/072207. Here, the particle size of the reactive oxides is 0.1-4 m, preferably 0.1 to 20 m.

(35) Test conditions: pellet test and flow test both at atmospheric pressure firing conditions and vacuum firing conditions at 400, 100, 10, 0.1 and 0.01 mbar.

(36) Success criteria: wetting and bonding to the glass substrate, no foaming in the pellet tests, as well as in the cross sections.

(37) The results are promising, there is good bonding to the float glass. Flow at temperatures 450 C., more preferably 420 C., no foaming during vacuum firing.

(38) Preferred reactive oxides: Y.sub.2O.sub.3, ZnO, Bi.sub.2O.sub.3, Al.sub.2O.sub.3

(39) It is also possible to use mixtures of the reactive oxides.

(40) It is also conceivable, after the application of vacuum, to fill the vacuum device with inert gas (N.sub.2 or argon) to protect certain components during the joining process.

(41) In the following two examples will be described specifically.

Example 1: Addition of Different Amounts of a Bismuth-Containing Glass to a Tellurium Vanadium Glass

(42) 5 wt % or 10 wt % EG9824 were added to TDF9533a. (TDF9533a, composition TeO.sub.2 56.00 wt %, V.sub.2O.sub.5 32.00 wt % and Al.sub.2O.sub.3 12.00 wt %, EG9824A7: Bi.sub.2O.sub.3ZnOB.sub.2O.sub.3 glass). Table 1 shows clearly the increase in the softening point and the respective temperatures with increasing concentration of EG9824.

(43) TABLE-US-00005 TABLE 1 Heating microscopy Addition of bi glass TDF9533a TDF9533a TDF9533a wt % 0 5 10 vol % 0 2.9 6 Softening point ( C.) 352 352 372 Ball point temperature ( C.) 377 386 413 Hemisphere point temperature ( C.) 435 452 505 Flow temperature ( C.) 920 985 992

Example 2: Addition of Different Amounts of Al.SUB.2.O.SUB.3 .to a Tellurium Vanadium Glass

(44) TABLE-US-00006 TABLE 2 Heating microscopy Addition of Al.sub.2O.sub.3 TDF9533a TDF9533a TDF9533a wt % 0 5 10 vol % 0 5.6 11.2 Softening point ( C.) 323 346 369 Ball point temperature ( C.) 335 378 400 Hemisphere point temperature ( C.) 397 433 475 Flow temperature ( C.) 426 499 >1350

Example 3 Addition of Different Amounts of SiO.SUB.2 .to a Tellurium Vanadium Glass

(45) TABLE-US-00007 TABLE 3 Heating microscopy Addition of SiO.sub.2 TDF9533a TDF9533a TDF9533a TDF9533a wt % 0 5 10 20 vol % 0 9.1 17.5 32.3 Softening point ( C.) 323 352 347 412 Ball point temperature 335 387 436 ( C.) Hemisphere point 397 447 temperature ( C.) Flow temperature ( C.) 426 1010 >1350 >1350

(46) If there is no information in the table, the temperature is not reached.

(47) The changes in the softening point, the ball point temperature at vol % 0 are due to the use of different particle sizes of the cordierite filler. A particle size of cordierite of d50 of about 20 m has proven to be suitable.

(48) Figure shows the dependence of the ball point temperature on the volume concentration of the additive.