US20060228476A1 - Method for depositing tin oxide and titanium oxide coatings on flat glass and the resulting coated glass - Google Patents
Method for depositing tin oxide and titanium oxide coatings on flat glass and the resulting coated glass Download PDFInfo
- Publication number
- US20060228476A1 US20060228476A1 US11/447,862 US44786206A US2006228476A1 US 20060228476 A1 US20060228476 A1 US 20060228476A1 US 44786206 A US44786206 A US 44786206A US 2006228476 A1 US2006228476 A1 US 2006228476A1
- Authority
- US
- United States
- Prior art keywords
- titanium dioxide
- coating
- substrate
- glass
- film
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 title claims abstract description 106
- 239000011521 glass Substances 0.000 title claims abstract description 80
- 238000000034 method Methods 0.000 title claims abstract description 62
- 238000000576 coating method Methods 0.000 title abstract description 155
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 title abstract description 47
- 238000000151 deposition Methods 0.000 title abstract description 44
- 229910001887 tin oxide Inorganic materials 0.000 title abstract description 33
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 title description 32
- 239000005357 flat glass Substances 0.000 title description 11
- 239000000758 substrate Substances 0.000 claims abstract description 66
- 238000005229 chemical vapour deposition Methods 0.000 claims abstract description 12
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 34
- 239000000377 silicon dioxide Substances 0.000 claims description 15
- 238000004519 manufacturing process Methods 0.000 claims description 10
- 238000002834 transmittance Methods 0.000 claims description 6
- 239000004408 titanium dioxide Substances 0.000 claims 29
- 239000011941 photocatalyst Substances 0.000 claims 13
- 229910052681 coesite Inorganic materials 0.000 claims 4
- 229910052906 cristobalite Inorganic materials 0.000 claims 4
- 230000001699 photocatalysis Effects 0.000 claims 4
- 229910052682 stishovite Inorganic materials 0.000 claims 4
- 229910052905 tridymite Inorganic materials 0.000 claims 4
- 239000013078 crystal Substances 0.000 claims 1
- 238000007598 dipping method Methods 0.000 claims 1
- 239000004615 ingredient Substances 0.000 claims 1
- 239000011248 coating agent Substances 0.000 abstract description 117
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 abstract description 37
- 239000001301 oxygen Substances 0.000 abstract description 37
- 229910052760 oxygen Inorganic materials 0.000 abstract description 37
- 230000008021 deposition Effects 0.000 abstract description 36
- 150000002148 esters Chemical class 0.000 abstract description 30
- 229910052751 metal Inorganic materials 0.000 abstract description 23
- 239000002184 metal Substances 0.000 abstract description 23
- 150000001875 compounds Chemical class 0.000 abstract description 20
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 abstract description 18
- KPZGRMZPZLOPBS-UHFFFAOYSA-N 1,3-dichloro-2,2-bis(chloromethyl)propane Chemical compound ClCC(CCl)(CCl)CCl KPZGRMZPZLOPBS-UHFFFAOYSA-N 0.000 abstract description 17
- 239000001257 hydrogen Substances 0.000 abstract description 15
- 229910052739 hydrogen Inorganic materials 0.000 abstract description 15
- 150000004831 organic oxygen compounds Chemical class 0.000 abstract description 12
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 abstract description 11
- 125000000217 alkyl group Chemical group 0.000 abstract description 9
- 239000007789 gas Substances 0.000 description 88
- 239000002243 precursor Substances 0.000 description 63
- 239000000203 mixture Substances 0.000 description 58
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 57
- HPGGPRDJHPYFRM-UHFFFAOYSA-J tin(iv) chloride Chemical compound Cl[Sn](Cl)(Cl)Cl HPGGPRDJHPYFRM-UHFFFAOYSA-J 0.000 description 22
- 229910021627 Tin(IV) chloride Inorganic materials 0.000 description 21
- 238000006243 chemical reaction Methods 0.000 description 18
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 description 17
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 16
- 229910044991 metal oxide Inorganic materials 0.000 description 16
- 150000004706 metal oxides Chemical class 0.000 description 16
- 238000000354 decomposition reaction Methods 0.000 description 15
- 150000002894 organic compounds Chemical class 0.000 description 15
- 239000010410 layer Substances 0.000 description 12
- 239000012298 atmosphere Substances 0.000 description 11
- DKPFZGUDAPQIHT-UHFFFAOYSA-N butyl acetate Chemical compound CCCCOC(C)=O DKPFZGUDAPQIHT-UHFFFAOYSA-N 0.000 description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 10
- 239000005329 float glass Substances 0.000 description 10
- 239000001307 helium Substances 0.000 description 10
- 229910052734 helium Inorganic materials 0.000 description 10
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 10
- 238000005979 thermal decomposition reaction Methods 0.000 description 10
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 9
- 238000006124 Pilkington process Methods 0.000 description 9
- 230000015572 biosynthetic process Effects 0.000 description 9
- 229910052799 carbon Inorganic materials 0.000 description 9
- 239000012159 carrier gas Substances 0.000 description 9
- 239000000376 reactant Substances 0.000 description 9
- 229910052757 nitrogen Inorganic materials 0.000 description 8
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 7
- 239000003570 air Substances 0.000 description 7
- 230000001590 oxidative effect Effects 0.000 description 7
- 230000003068 static effect Effects 0.000 description 7
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 6
- 238000000137 annealing Methods 0.000 description 6
- 229910052731 fluorine Inorganic materials 0.000 description 6
- 239000011737 fluorine Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- XBDQKXXYIPTUBI-UHFFFAOYSA-M Propionate Chemical compound CCC([O-])=O XBDQKXXYIPTUBI-UHFFFAOYSA-M 0.000 description 5
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 5
- 239000002019 doping agent Substances 0.000 description 5
- FUZZWVXGSFPDMH-UHFFFAOYSA-N hexanoic acid Chemical compound CCCCCC(O)=O FUZZWVXGSFPDMH-UHFFFAOYSA-N 0.000 description 5
- 239000007788 liquid Substances 0.000 description 5
- 229910052710 silicon Inorganic materials 0.000 description 5
- 239000010703 silicon Substances 0.000 description 5
- WMOVHXAZOJBABW-UHFFFAOYSA-N tert-butyl acetate Chemical compound CC(=O)OC(C)(C)C WMOVHXAZOJBABW-UHFFFAOYSA-N 0.000 description 5
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical group [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 4
- 125000004432 carbon atom Chemical group C* 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 4
- FKRCODPIKNYEAC-UHFFFAOYSA-N ethyl propionate Chemical compound CCOC(=O)CC FKRCODPIKNYEAC-UHFFFAOYSA-N 0.000 description 4
- 239000007800 oxidant agent Substances 0.000 description 4
- 229910052814 silicon oxide Inorganic materials 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 3
- WFDIJRYMOXRFFG-UHFFFAOYSA-N Acetic anhydride Chemical compound CC(=O)OC(C)=O WFDIJRYMOXRFFG-UHFFFAOYSA-N 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- WBJINCZRORDGAQ-UHFFFAOYSA-N formic acid ethyl ester Natural products CCOC=O WBJINCZRORDGAQ-UHFFFAOYSA-N 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 150000002431 hydrogen Chemical class 0.000 description 3
- 229910000040 hydrogen fluoride Inorganic materials 0.000 description 3
- -1 isobutyl alcohols Chemical class 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 239000006060 molten glass Substances 0.000 description 3
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 238000002310 reflectometry Methods 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- ZTQSAGDEMFDKMZ-UHFFFAOYSA-N Butyraldehyde Chemical compound CCCC=O ZTQSAGDEMFDKMZ-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- BDAGIHXWWSANSR-UHFFFAOYSA-M Formate Chemical compound [O-]C=O BDAGIHXWWSANSR-UHFFFAOYSA-M 0.000 description 2
- RMOUBSOVHSONPZ-UHFFFAOYSA-N Isopropyl formate Chemical compound CC(C)OC=O RMOUBSOVHSONPZ-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 2
- DTQVDTLACAAQTR-UHFFFAOYSA-N Trifluoroacetic acid Chemical compound OC(=O)C(F)(F)F DTQVDTLACAAQTR-UHFFFAOYSA-N 0.000 description 2
- KXKVLQRXCPHEJC-UHFFFAOYSA-N acetic acid trimethyl ester Natural products COC(C)=O KXKVLQRXCPHEJC-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 2
- 239000008246 gaseous mixture Substances 0.000 description 2
- JMMWKPVZQRWMSS-UHFFFAOYSA-N isopropanol acetate Natural products CC(C)OC(C)=O JMMWKPVZQRWMSS-UHFFFAOYSA-N 0.000 description 2
- 229940011051 isopropyl acetate Drugs 0.000 description 2
- 125000001449 isopropyl group Chemical group [H]C([H])([H])C([H])(*)C([H])([H])[H] 0.000 description 2
- GWYFCOCPABKNJV-UHFFFAOYSA-M isovalerate Chemical compound CC(C)CC([O-])=O GWYFCOCPABKNJV-UHFFFAOYSA-M 0.000 description 2
- 239000006193 liquid solution Substances 0.000 description 2
- 239000003595 mist Substances 0.000 description 2
- 150000002895 organic esters Chemical class 0.000 description 2
- 150000004812 organic fluorine compounds Chemical class 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000010944 pre-mature reactiony Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 235000012773 waffles Nutrition 0.000 description 2
- 239000011787 zinc oxide Substances 0.000 description 2
- 241000251468 Actinopterygii Species 0.000 description 1
- FERIUCNNQQJTOY-UHFFFAOYSA-N Butyric acid Chemical class CCCC(O)=O FERIUCNNQQJTOY-UHFFFAOYSA-N 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- NTIZESTWPVYFNL-UHFFFAOYSA-N Methyl isobutyl ketone Chemical compound CC(C)CC(C)=O NTIZESTWPVYFNL-UHFFFAOYSA-N 0.000 description 1
- UIHCLUNTQKBZGK-UHFFFAOYSA-N Methyl isobutyl ketone Natural products CCC(C)C(C)=O UIHCLUNTQKBZGK-UHFFFAOYSA-N 0.000 description 1
- STSCVKRWJPWALQ-UHFFFAOYSA-N TRIFLUOROACETIC ACID ETHYL ESTER Chemical compound CCOC(=O)C(F)(F)F STSCVKRWJPWALQ-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 150000001336 alkenes Chemical class 0.000 description 1
- 239000012080 ambient air Substances 0.000 description 1
- 230000008033 biological extinction Effects 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 150000001722 carbon compounds Chemical class 0.000 description 1
- 150000001728 carbonyl compounds Chemical class 0.000 description 1
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- UHZZMRAGKVHANO-UHFFFAOYSA-M chlormequat chloride Chemical compound [Cl-].C[N+](C)(C)CCCl UHZZMRAGKVHANO-UHFFFAOYSA-M 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 239000012809 cooling fluid Substances 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000003085 diluting agent Substances 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005485 electric heating Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910001510 metal chloride Inorganic materials 0.000 description 1
- 238000001465 metallisation Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 125000004108 n-butyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 1
- 125000004123 n-propyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])* 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000005546 reactive sputtering Methods 0.000 description 1
- 230000002829 reductive effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 125000000999 tert-butyl group Chemical group [H]C([H])([H])C(*)(C([H])([H])[H])C([H])([H])[H] 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 150000003606 tin compounds Chemical class 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 150000003609 titanium compounds Chemical class 0.000 description 1
- HGBOYTHUEUWSSQ-UHFFFAOYSA-N valeric aldehyde Natural products CCCCC=O HGBOYTHUEUWSSQ-UHFFFAOYSA-N 0.000 description 1
- 239000003039 volatile agent Substances 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
- C03C17/22—Surface treatment of glass, not in the form of fibres or filaments, by coating with other inorganic material
- C03C17/23—Oxides
- C03C17/245—Oxides by deposition from the vapour phase
- C03C17/2453—Coating containing SnO2
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
- C03C17/22—Surface treatment of glass, not in the form of fibres or filaments, by coating with other inorganic material
- C03C17/23—Oxides
- C03C17/245—Oxides by deposition from the vapour phase
- C03C17/2456—Coating containing TiO2
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
- C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
- C23C16/40—Oxides
- C23C16/405—Oxides of refractory metals or yttrium
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C2217/00—Coatings on glass
- C03C2217/20—Materials for coating a single layer on glass
- C03C2217/21—Oxides
- C03C2217/211—SnO2
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C2217/00—Coatings on glass
- C03C2217/20—Materials for coating a single layer on glass
- C03C2217/21—Oxides
- C03C2217/212—TiO2
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C2218/00—Methods for coating glass
- C03C2218/10—Deposition methods
- C03C2218/15—Deposition methods from the vapour phase
- C03C2218/152—Deposition methods from the vapour phase by cvd
Definitions
- This invention relates to a process for depositing titanium oxide and tin oxide coatings on a flat glass substrate, and the resulting coated glass. More particularly, this invention relates to a chemical vapour deposition process for producing titanium oxide and tin oxide coatings on flat glass using a coating precursor gas mixture comprising the corresponding metal tetrachloride and an organic oxidant.
- Titanium oxide and tin oxide coatings have been proposed for use on glass containers, for example bottles, to improve the mechanical strength of the containers. It has also been proposed to use both titanium oxide and tin oxide coatings on flat glass to modify the characteristics of the glass for architectural use; titanium oxide coatings deposited under vacuum (by reactive sputtering) are used as components of sputtered multi-layer infrared reflecting coatings, while tin oxide coatings are used, not only as layers of multi-layer sputtered coatings, but also deposited pyrolytically with a dopant as infrared reflecting and/or electroconducting coatings.
- GB patent specification 1,115,342 describes a process for producing glass containers with good inherent strength and good abrasion resistance by spraying the containers, while still hot from the manufacturing process, with a solution or dispersion of stannic chloride (that is, tin tetrachloride) in an organic liquid, isopropyl alcohol being preferred.
- stannic chloride that is, tin tetrachloride
- a small amount of titanium chloride may be incorporated as a modifier.
- the liquid solution is fed to atomisers, which may be of the pressure jet variety, located on either side of a tunnel over a conveyor for hot glass bottles to produce a ‘mist of liquid reagent’ so that a layer of liquid is formed on all the external surfaces of the bottles where it reacts to form a layer of tin oxide.
- GB patent specification 1,187,784 describes an improvement of the process described in GB patent specification 1,115,342 and apparently more suitable for incorporation into a process for the automatic manufacture of glassware without interfering with the normal running of such process and without requiring additional supervision.
- the specification proposes to treat glass containers, at high temperature, with a liquid solution of an organic compound of tin “which compound has properties such that upon application of heat it decomposes into two materials, one of which is an organic compound of tin of high decomposition temperature which reacts with the glass surface to produce a diffusion layer of tin oxide within the glass surface, while the other is a volatile compound of tin such that a substantial proportion of vapour of said compound is produced, and subjecting the containers to a heat treatment such that a reaction is caused to occur between the glass at least the surfaces of the containers and the tin compounds”.
- the material used for treating the glass containers may be provided by reacting tin tetrachloride with organic substances containing carbonyl groups of moderate activity e.g. organic esters of ethyl, n-propyl, isopropyl, n-butyl and isobutyl alcohols with acetic, propionic and butyric acids.
- organic substances containing carbonyl groups of moderate activity e.g. organic esters of ethyl, n-propyl, isopropyl, n-butyl and isobutyl alcohols with acetic, propionic and butyric acids.
- the resulting solution may be sprayed, in the presence of ambient atmosphere, on to the hot containers e.g. in the form of a fine mist after they leave the forming machine and before they enter the annealing lehr.
- GB patent specification 1 187 783 describes an analogous process to that described in 1 187 784 in which an organic compound of titanium is sprayed on to the hot glass containers in place of the organic compound of tin.
- the organic titanium compound may be produced, in an analogous manner to the organic compound of tin, by reacting titanium tetrachloride with an organic ester e.g. n-butyl acetate. Again, the resulting solution is sprayed onto the glass in the ambient atmosphere on the container production line.
- tin tetrachloride applied either as a liquid spray or, more recently, in gaseous form, to apply a tin oxide coating to hot flat glass to form an electroconductive, infra-red reflecting coating on the hot glass surface; water is used to hydrolyse the tin tetrachloride and as a source of oxygen for formation of the tin oxide.
- GB patent specification 2 044 137A relates to such a process in which discrete laminar streams of each reactant are formed and projected on to a hot glass substrate by bringing the streams together in reciprocal tangential contact over the glass.
- Titanium tetrachloride may be used as one of the gaseous reactants, in place of the tin tetrachloride, in order to form a titanium oxide coating.
- the patent also suggests supplying hydrogen to one of the gas streams to attenuate the violent reaction between the tin tetrachloride and the water vapour. This may be done either by direct addition of gaseous hydrogen, or by the addition of methanol, which is said to react in situ to produce the desired gaseous hydrogen.
- GB patent specification 2 026 454B describes a process in which a coating chamber is positioned over a hot float glass ribbon as it advances from the float bath and successive gaseous streams of (1) preheated nitrogen carrier gas, (2) tin tetrachloride entrained in preheated nitrogen and (3) air, water vapour and hydrofluoric acid are introduced into the coating chamber so they flow along the glass substrate surface being coated as a substantially turbulence free layer.
- the patent specifies the concentration of water vapour and tin tetrachloride in the gaseous medium over the glass.
- European patent specifications 0 365 239B1 and 0 376 240B1 describe a method and apparatus for depositing a tin oxide coating on a hot glass ribbon.
- a first gaseous stream of tin tetrachloride in preheated dry air is caused to flow along the surface of the hot ribbon of glass advancing beneath a coating chamber, a second turbulent stream of hydrofluoric acid and steam introduced into the coating chambers at right angles to the plane of the glass and direction of flow of the first gaseous stream, and the combined first and second gas streams drawn through the coating chamber over the glass under turbulent flow conditions.
- the method and apparatus may also be used to apply a coating of titanium oxide using titanium tetrachloride in place of the tin tetrachloride.
- U.S. Pat. No. 4,590,096 describes a process in which a coating solution comprising a substantially solvent free mixture of an organotin chloride and a reactive organic fluorine compound soluble in or miscible with the organotin chloride is introduced to a preheated carrier gas stream which contains sufficient water vapour that the relative humidity of the gas stream at 18° C. is about 6% to about 100%.
- the resulting gas stream is passed over a hot glass surface to deposit a fluorine doped tin oxide coating on the hot glass.
- organotin compounds may be used, and the possibility of using tin tetrachloride is mentioned.
- organic fluorine compounds including oxygen containing compounds, for example trifluoroacetic acid and ethyltrifluoroacetate
- fluorine-containing dopants have limited solubilities in the organotin compounds used, and an optional solubiliser may be used to increase the solubility of the fluorine dopant on the organotin compound; acetic anhydride, ethyl acetate, hexane, methyl isobutyl ketone and butyraldehyde are listed as non-limiting examples of the solubilisers that may be used.
- the U.S. patent in common with the other patents utilising chemical vapour deposition methods to deposit a metal oxide from a gaseous metal tetrachloride, utilises water vapour as the source of oxygen.
- Vijaykumar et al is concerned with deposition of zinc oxide coatings by chemical vapour deposition at low temperature (60° to 350° C., preferably 100° to 200° C.) on heat sensitive photoconductor substrates, and proposes to deposit the zinc oxide coatings from an organozinc compound and an oxidant, which may be an oxygen containing organic compound e.g. an ester, and an inert carrier gas.
- an organozinc compound and an oxidant which may be an oxygen containing organic compound e.g. an ester, and an inert carrier gas.
- High deposition rates are important when coating substrates in a manufacturing process. This is particularly true for an on-line float glass process where the glass ribbon is traveling at a specific line speed and where the ribbon requires a specific coating thickness.
- the deposition rates obtained with the preferred embodiments of the present invention may be ten times higher than the deposition rates with other known methods for depositing titanium oxide coatings.
- Especially high deposition rates, particularly for titanium oxide may be achieved with the present invention using a precursor mixture including an ester with a ⁇ hydrogen.
- Another object of the present invention is to provide a method for obtaining a tin oxide or titanium oxide coating wherein the thickness of the coating can be varied based upon the particular organic compound utilized as a source of oxygen in the precursor mixture.
- a further object is to obtain a titanium oxide coating at high deposition rates with a refractive index of at least 2.4.
- a still further object is to produce tin and titanium oxide coatings at high deposition rates using low cost chlorinated precursors.
- a chemical vapour deposition process for laying down a tin oxide or titanium oxide coating on a hot glass substrate using a precursor gas mixture containing the corresponding metal tetrachloride and an organic source of oxygen, without the requirement for inclusion of water vapour and the consequent risk of premature reaction.
- the present invention provides a process for depositing a tin oxide or titanium oxide coating on hot flat glass comprising the steps of
- oxygen-containing organic compounds may be used as the source of oxygen, without requiring the presence of water vapour or gaseous oxygen, including compounds normally considered reducing agents rather than oxidising agents, for example, alcohols.
- the preferred organic compounds are carbonyl compounds, especially esters; and particularly good results have been obtained using esters having an alkyl group with a ⁇ hydrogen.
- the alkyl group with a ⁇ hydrogen will normally contain two to ten carbon atoms.
- organic compounds especially esters, containing from two to ten carbon atoms, since larger molecules tend to be less volatile and hence less convenient for use in the CVD process of the present invention.
- esters for use in the practice of the present invention include ethyl formate, ethyl acetate, ethyl propionate, isopropyl formate, isopropyl acetate, n-butyl acetate and t-butyl acetate.
- the method of the present invention is generally practiced in connection with the formation of a continuous glass ribbon substrate, for example during a float glass production process.
- the method of the present invention may be employed in coating other flat glass substrates either on-line or off-line.
- the present invention involves the preparation of a precursor gas mixture which includes tin or titanium tetrachloride and an organic oxygen containing compound; a carrier gas or diluent, for example, nitrogen, air or helium, will normally also be included in the gas mixture. Since thermal decomposition of the organic oxygen containing compound may initiate the metal oxide deposition reaction at a high rate, it is desirable that the precursor mixture be kept at a temperature below the thermal decomposition temperature of the organic oxygen compound to prevent prereaction of the gaseous mixture with formation of the metal oxide.
- the gaseous mixture is maintained at a temperature below that at which it reacts to form the metal oxide, and delivered to a location near a flat glass substrate to be coated, the substrate being at a temperature above said reaction temperature (and above the decomposition temperature of the organic oxygen compound in the precursor gas mixture).
- the precursor gas mixture is thereafter introduced into the vapor space directly over the substrate.
- the heat from the substrate raises the temperature of the precursor gas above the thermal decomposition temperature of the organic oxygen compound.
- the organic oxygen compound then decomposes with reaction with the metal tetrachloride producing a metal dioxide coating on the substrate.
- the present invention permits the production of tin and titanium oxide coatings deposited on the hot glass at a high deposition rate e.g. over 130 ⁇ /second and, in preferred embodiments, over 250 ⁇ per second.
- the deposition rate is dependent upon the particular organic oxygen containing compound used, and the concentrations of both the organic oxygen containing compound and the metal chloride, as well as the temperature of the glass.
- the optimum concentrations (and in particular the optimum proportion of organic oxygen containing compound to metal tetrachloride) and flow rates for rapid coating deposition may be determined by simple trial.
- the use of higher concentrations of reactants and high gas flow rates is likely to result in a less efficient overall conversion of the reactants into coating, so that the optimum condition for commercial operation may differ from the conditions which provide the highest deposition rates.
- the method of the invention permits the production, at high rates, of titanium oxide and tin oxide coatings on hot flat glass substrates on line during the glass production process.
- the titanium oxide coatings may be produced with a high refractive index (at least 2.4) permitting the achievement of desired optical effects, especially when used in combination with other coating layers.
- the tin oxide coatings may be doped, for example with fluorine, increasing their electrical conductivity and infra red reflectivity, and hence their utility as electrical conducting coatings and/or low emissivity coatings in architectural glazing and other applications.
- FIG. 1 is a schematic view of a vertical section of an apparatus for practicing a float glass process which includes gas distributors suitably positioned to enable the practicing of the method of the present invention.
- FIG. 2 is broken sectional view of an article coated according to this invention.
- FIG. 3 is an enlarged schematic end view of a gas distributor beam suitable for use in practicing the present invention.
- FIG. 4 is an enlarged schematic end view of an alternative gas distributor beam which may be used in practicing the present invention.
- the float glass apparatus more particularly comprises a canal section 12 along which molten glass 14 is delivered from a melting furnace (not shown), to a float bath section 16 wherein a continuous glass ribbon 18 is formed in accordance with the well known float process.
- the glass ribbon 18 advances from the bath section 16 through an adjacent annealing lehr 20 and a cooling section 22 .
- the continuous glass ribbon 18 serves as the substrate upon which the metal oxide coating is deposited in accordance with the present invention.
- the float section 16 includes a bottom section 24 within which a bath of molten tin 26 is contained, a roof 28 , opposite sidewalls 30 , and end walls 32 .
- the roof 28 , side walls 30 , and end walls 32 together define an enclosure 34 in which a non-oxidizing atmosphere is maintained to prevent oxidation of the molten tin.
- gas distributor beams 64 , 66 and 68 are located in the bath section 16 .
- the gas distributor beams 64 and 66 in the bath section may be employed to apply additional coatings onto the substrate prior to applying the tin or titanium oxide coating by the method of the present invention.
- the additional coatings may include silicon and silica.
- the molten glass 14 flows along the canal 36 beneath a regulating tweel 38 and downwardly onto the surface of the tin bath 26 in controlled amounts.
- the molten glass spreads laterally under the influences of gravity and surface tension, as well as certain mechanical influences, and it is advanced across the bath to form the ribbon 18 .
- the ribbon is removed over lift out rolls 40 and is thereafter conveyed through the annealing lehr 20 and the cooling section 22 on aligned rolls 42 .
- the application of the coating of the present invention may take place in the float bath section 16 , or further along the production line, for example in the gap between the float bath and the annealing lehr, or in the annealing lehr.
- a suitable non-oxidizing atmosphere generally nitrogen or a mixture of nitrogen and hydrogen in which nitrogen predominates, is maintained in the bath enclosure 34 to prevent oxidation of the tin bath.
- the atmosphere gas is admitted through conduits 44 operably coupled to a distribution manifold 46 .
- the non-oxidizing gas is introduced at a rate sufficient to compensate for normal losses and maintain a slight positive pressure, on the order of about 0.001 to about 0.01 atmosphere above ambient atmospheric pressure, so as to prevent infiltration of outside atmosphere.
- Heat for maintaining the desired temperature regime in the tin bath 26 and the enclosure 34 is provided by radiant heaters 48 within the enclosure.
- the atmosphere within the lehr 20 is typically atmospheric air, while the cooling section 22 is not enclosed and the glass ribbon is open to the ambient atmosphere.
- Ambient air may be directed against the glass ribbon as by fans 50 in the cooling section.
- Heaters (not shown) may also be provided within the annealing lehr for causing the temperature of the glass ribbon to be gradually reduced in accordance with a predetermined regime as it is conveyed therethrough.
- FIG. 1 illustrates the use of gas distributor beams 64 , 66 and 68 positioned in the float bath 16 to deposit the various coatings on the glass ribbon substrate.
- the gas distributor beam is one form of reactor that can be employed in practicing the process of the present invention.
- FIG. 3 A conventional configuration for the distributor beams suitable for supplying the precursor materials in accordance with the invention is shown generally schematically at FIG. 3 .
- a suitable heat exchange medium is circulated through the enclosed cavities 76 , 78 in order to maintain the distributor beams at a desired temperature.
- the precursor gas mixture is supplied through a fluid cooled supply conduit 80 .
- the supply conduit 80 extends along the distributor beam and admits the gas through drop lines 82 spaced along the supply conduit.
- the supply conduit 80 leads to a delivery chamber 84 within a header 86 carried by the framework.
- Precursor gases admitted through the drop lines 82 are discharged from the delivery chamber 84 through a passageway 88 toward a coating chamber defining a vapour space opening on to the glass where they flow along the surface of the glass 18 in the direction of the arrows in FIG. 3 .
- Baffle plates 90 may be provided within the delivery chamber 84 for equalizing the flow of precursor materials across the distributor beam to assure that the materials are discharged against the glass 18 in a smooth, laminar, uniform flow entirely across the distributor beam. Spent precursor materials are collected and removed through exhaust chambers 92 along the sides of the distributor beam.
- distributor beams used for chemical vapour deposition are suitable for the present method and are known in the prior art.
- FIG. 4 of the drawings One such an alternative distributor beam configuration is illustrated schematically in FIG. 4 of the drawings.
- this distributor which is generally designated 100 (and more fully described in European patent EP 0 305 102B)
- the precursor gas mixture is introduced through a gas supply duct 101 where it is cooled by cooling fluid circulated through ducts 102 and 103 .
- Gas supply duct 101 opens through an elongated aperture 104 into a gas flow restrictor 105 .
- Gas flow restrictor 105 is of the kind more fully described in UK patent specifications GB 1 507 996, and comprises a plurality of metal strips longitudinally crimped in the form of a sine wave and vertically mounted in abutting relationship with one another extending along the length of the distributor. Adjacent crimped metal strips are arranged “out of phase” to define a plurality of vertical channels between them. These vertical channels are of small cross-sectional area relative to the cross-sectional area of gas supply duct 101 , so that the gas is released from the gas flow restrictor 105 at substantially constant pressure along the length of the distributor.
- the coating gas is released from the gas flow restrictor into the inlet side 107 of a substantially U-shaped guide channel generally designated 106 comprising inlet leg 107 , coating chamber 108 which opens onto the hot glass substrate 110 to be coated, and exhaust leg 109 , whereby used coating gas is withdrawn from the glass.
- the rounded corners of the blocks defining the coating channel promote a uniform laminar flow of coating parallel to the glass surface across the glass surface to be coated.
- Example 1 the glass was heated on a conveyor furnace to simulate the coating reaction conditions of a float glass process in order to test the method of the present invention.
- the furnace utilized in-line rollers to convey a glass substrate through a heating zone prior to practicing the method of the present invention.
- the glass substrate was float glass which had been initially provided with a silica coating.
- the silica coating was deposited on the float glass through a known chemical vapour deposition process utilizing a precursor of monosilane in an oxygen enriched atmosphere.
- the silica deposition forms no part of the present invention.
- a titanium oxide coating was deposited on the silica coated substrate.
- the substrate was at a temperature of a 1170° F./630° C. and the substrate line speed was at 300 inches/8 metres per minute.
- a precursor gas mixture comprising titanium tetrachloride, ethyl acetate, oxygen, and helium.
- Helium was included in the precursor mixture as a carrier for the reactants.
- the precursor mixture was prepared by simultaneously introducing all four gas streams through a manifold system. An in line static mixer was used to ensure a homogeneous precursor mixture.
- the volume percent composition of the precursor mixture was 0.7% titanium tetrachloride, 17.2% ethyl acetate, 7.2% oxygen, and 74.9% helium, with the flow rates for the components at the manifold being as shown in the accompanying Table 1.
- the temperature of the precursor mixture was kept above 300° F./150° C. in order to prevent the adduct reaction of titanium tetrachloride and ethyl acetate.
- the precursor temperature was also kept below the 950° F.-1130° F. (510° C.-610° C.) thermal decomposition temperature range of ethyl acetate in order to prevent the mixture from prereacting.
- the precursor mixture was introduced into the reactor just above the moving substrate.
- the temperature at the precursor tower was 250° F./120° C.
- the temperature at the reactor face was 350° F./175° C.
- the higher substrate temperature initiated the thermal decomposition of the ethyl acetate which then resulted in the deposition of the titanium oxide.
- the resulting coated glass was allowed to cool in air and the coating analysed. It was found to be titanium oxide with a carbon content of 2.5-3.5 atomic percent.
- the thickness of the titanium oxide coating was measured 490 ⁇ and the thickness and growth rate (150 ⁇ per second) are shown in Table 1.
- the optical properties of the resulting product included an observed Illuminant C transmittance (10° observer) of 62.3% and an observed Illuminant C reflectivity of 35.6%.
- the extinction coefficient was 0.008 at 550 nm, and the refractive index of the titanium oxide coating was 2.44.
- Example 2 the coating procedure set out in Example 1 was repeated, except that in Example 2 ethyl formate was used as the organic source of oxygen, and in Example 3 isopropanol was used as the organic source of oxygen and uncoated glass (in place of the silicon oxide coated glass of Examples 1 and 2) was used as the substrate.
- the gas flow rates used and, in the case of Example 2, the thickness and growth rate of the titanium oxide coating produced are shown in Table 1.
- Example 3 the isopropanol burned in the reactor leaving only particulate titanium oxide on the glass, the corresponding deposition rate therefore being quoted as 0 ⁇ /second.
- Example 4 The procedure for Examples 4 and 5 was as used in the previous Examples (the reactor temperature and the substrate being identical to Example 1), except that the substrate was static and not dynamic.
- the static sample was positioned under the reactor for 10 seconds. Under static conditions, the residence time of the substrate under the reactor is increased from the dynamic conditions by a factor of five.
- Example 4 methyl acetate was used as the organic source of oxygen, and in Example 5 t-butyl acetate was used; in each case a titanium oxide coating was produced.
- the gas flow rates, resulting titanium oxide coating thickness and coating growth rates are as shown in Table 1. The relatively slow growth rate achieved using methyl acetate is discussed hereinafter.
- a float glass process was used in producing a continuous glass ribbon having a thickness of 0.125 inches/3 mm at a line speed of 434 inches/11 metres per minute.
- the glass temperature was at 1140° F./615° C. at the desired point of application in the float bath section of a titanium oxide coating using a coating reactor similar to that shown in FIG. 3 .
- the temperature at the precursor tower was 400° F./205° C. and the temperature at the reactor face was 500° F./260° C.
- a silica coating was deposited on the glass substrate in the float bath section at a thickness of about 339 ⁇ .
- the same chemical vapor deposition process as described in Example 1 was used to deposit the silica coating.
- the silica deposition forms no part of the present invention.
- the precursor gas mixture was developed comprising titanium tetrachloride and ethyl acetate in a helium carrier gas. Oxygen was not used in the precursor as result of earlier Examples indicated that the coating reaction was not sensitive to the oxygen concentration.
- the precursor mixture was prepared by simultaneously introducing the three components through a manifold system. The volume percent composition of the precursor mixture was 0.6% titanium tetrachloride, 1.8% ethyl acetate, and 97.5% helium. The flow rates for the components were 480.0 l/m of helium, 3.0 l/m of titanium tetrachloride, 9.2. l/m of ethyl acetate. The total flow rate for the precursor mixture was 492.2 l/m.
- the resulting titanium oxide coating was 684 ⁇ thick.
- the carbon content of the coating was less than 2 atomic percent.
- the growth rate of the coating was 309 ⁇ per second.
- Example 6 The same procedure carried out Example 6 was utilized in this Example.
- the substrate comprised coatings of silicon and then silica over the glass substrate.
- the coatings were deposited by a known chemical vapor deposition process in the float bath section.
- the silicon coating was deposited by CVD from monosilane with a non-oxidizing carrier gas.
- the silica coating was then deposited onto the silicon coating through the use of the same procedure as described in Example 1.
- the precursor for the titanium oxide coating included titanium tetrachloride and ethyl acetate in a helium carrier gas.
- the volume percent composition of the precursor was 0.5% titanium tetrachloride, 1.9% ethyl acetate, and 97.6% helium.
- the corresponding flow rates for the components were 480.0 l/m of helium, 2.4 l/m of titanium tetrachloride, 9.2 l/m of ethyl acetate.
- the total flow rate for the precursor mixture was 491.6 1 /m.
- the resulting coated article 52 is illustrated in FIG. 2 .
- the glass substrate 54 is depicted with a stack of multiple coatings 56 .
- the coatings comprise a layer of silicon 58 , a layer of silica 60 , then a titanium oxide coating 62 on top of the article.
- the titanium oxide coating on the resulting article had a thickness of 836 ⁇ .
- the optical properties of the resulting coating stack included an observed Illuminant C transmittance of 13.1% and an observed Illuminant C reflectivity of 82.5%.
- the growth rate of the titanium oxide coating was 378 ⁇ per second.
- the float glass to be coated was supported on a nickel block in a reactor vessel and the block heated from below by electric heating elements to provide a glass temperature of 1085° F./585° C.
- a flat graphite plate was mounted approximately 0.4 inches/10 mm above the glass and parallel thereto to provide a gas flow path 0.4 inches/10 mm deep between the glass surface bearing the silicon oxide layer and the plate.
- the total carrier gas flow rate was 13 m 3 /hour.
- the flow rates of the tin tetrachloride, and the nature and flow rates of the organic compound used, were as shown in the accompanying Table 2.
- small amounts of 40% hydrogen fluoride were incorporated in the-precursor gas mixture to dope the resulting tin oxide coating with fluorine, as shown in the Table.
- the gas flow containing the reactant gases was applied for approximately 8 seconds, and the coating apparatus and coated glass then allowed to cool under a flow of air at 345° F./225° C.
- the delivery gas line, nozzle and plate defining the gas flow path over the glass found to be free, in each case, from deposit, indicating an absence of undesirable prereaction.
- the glass had a tin oxide coating applied over the silicon oxide, the thickness of the coating varying with distance from the fishtail nozzle.
- the maximum thickness and corresponding growth rate for each precursor gas mixture used is shown in Table 2.
- the emissivity, resistivity and haze of the samples producing using hydrogen fluoride to incorporate a fluorine dopant (Examples 9 and 11) were measured and the results reported in Table 2.
- an organic source of oxygen can be used as part of a premixed precursor gas mixture comprising tin tetrachloride to deposit a tin oxide coating without significant undesirable prereaction detrimentally affecting the coating process e.g. by deposition of tin oxide in the gas supply ducts.
- a source of dopant such as hydrogen fluoride, may be incorporated in the gaseous premixture to reduce the emissivity and resistivity of the coating while continuing to avoid significant detrimental prereaction.
- a coating distributor as illustrated schematically in FIG. 4 was used in a float bath to apply a coating of tin oxide by a method in accordance with the invention.
- the ribbon speed was approximately 233 inches per minute/350 minutes per hour and the glass thickness was 0.05 inches/1.2 mm.
- the glass temperature was approximately 1170° F./630° C.
- the temperature of the gas supply duct 101 which served as a primary gas mixing chamber was maintained at 300° F./150° C. and the ‘static’ waffle gas distributor 105 was approximately 645° F./340° C.
- the tin tetrachloride and butyl acetate vapors were delivered by bubbling nitrogen through the liquids maintained at 175° F./80° C.
- the invention is a continuous chemical vapor deposition process for laying down tin oxide and titanium oxide coatings onto a glass substrate at high deposition rates through the use of the corresponding metal tetrachloride and an organic compound used as a source of oxygen in a preformed precursor gas mixture.
- the metal tetrachlorides are preferred sources of the respective metals because of the availability and cost of the raw material.
- an organic oxygen containing compound which is an ester, particularly an ester in which the group derived from the alcohol is an alkyl group with a ⁇ hydrogen.
- the decomposition temperature of the ester should not be greater than the reaction temperature of the coating precursor gas mixture at the desired point of application. Esters utilized in the precursor gas mixture that have a ⁇ hydrogen and appropriate decomposition temperatures will deposit the coatings at high deposition rates.
- the preferred group of esters used in practicing the present invention includes the group consisting of ethyl formate, ethyl acetate, ethyl propionate, isopropyl formate, isopropyl acetate, n-butyl acetate, and t-butyl acetate.
- the thermal decomposition temperature of the ester is defined as the temperature at which the unimolecular decomposition rate constant of the ester is 0.01/sec.
- the unimolecular decomposition rate constants of common esters such as ethyl acetate and t-butyl acetate are well known and can be found in the chemical literature.
- the thermal decomposition temperatures using the above definition are 935 and 650° Fahrenheit (500° C. and 344° C.), respectively.
- ester and specific deposition temperature employed will determine the optimum coating growth rate. Reaction temperatures below the defined thermal decomposition temperature, but within the decomposition range of the selected ester, will result in lower coating growth rates.
- the alkyl group of an ester used in the coating precursor gas mixture may be a carbon compound having a range of 2-10 carbon atoms.
- the lower limit of the range is dictated by the ⁇ hydrogen requirement on the alkyl group.
- the upper limit is to avoid flammability and volatility issues that arise when the alkyl group contains more than ten carbon atoms.
- a manifold may be used to connect and regulate the individual gas streams to formulate the coating precursor gas mixture.
- a common delivery line may be used to deliver the precursor gas mixture from the manifold to the gas beam distributor.
- An in line static mixer may be used in the delivery line to ensure a homogeneous gas mixture.
- the baffles in the gas distributor beam, illustrated in FIG. 3 , or a gas flow restrictor as described with reference to FIG. 4 may provide further mixing of the precursor gas at the reactor stage.
- oxygen was included in the coating precursor gas mixture.
- the deposition rate of the metal oxide coating was not sensitive to the oxygen concentrations, and no oxygen gas was used in Examples 6 or 7 showing the inclusion of oxygen to be unnecessary.
- the concentration of the reactive components of the coating precursor gas mixture may be selected to obtain the optimum coating growth rate.
- the concentration of metal tetrachloride is generally 0.1 to 5.0 percent by volume in the precursor gas mixture.
- the concentration of metal tetrachloride is based upon the amount of metal needed to provide the desired coating thickness in the available residence time.
- the metal tetrachloride concentration is adjusted according to process variables, such as the line speed of the ribbon in a float glass process.
- the concentration of the organic oxygen compound in the coating precursor gas mixture is generally one to five times the concentration of the metal tetrachloride, being selected within this range based upon the deposition temperature.
- concentration of the metal tetrachloride is 1 to 3 times the concentration of the titanium tetrachloride. Concentrations above or below the optimum range will produce metal oxide coatings at lower coating growth rates.
- the temperature of the precursor gas mixture is critical for control of the reaction, in particular to avoid undesirable pre-reaction or adduct formation resulting in formation of an involatile product in the precursor lines. In one preferred embodiment, especially applicable when using an ester, the temperature is maintained above 300° F./150° C. in the precursor gas lines.
- the precursor gas mixture is also preferably kept below the thermal decomposition temperature of the organic oxygen. compound to prevent prereaction of the mixture.
- the present inventive process utilizes the heat from the substrate to initialize the coating reaction.
- the substrate is formed at extremely high temperatures. Therefore, the method of the present invention may be applied at a point in the float glass process where the substrate temperature is lowered but is still above the temperature at which the coating is formed (and preferably after the glass ribbon has substantially finished stretching i.e. below 1380° F./750° C.).
- Off-line applications of the present invention will require heating the substrate to a temperature above the decomposition temperature of the ester.
- the preferred point of application is in the float bath section.
- the temperature range at the point of application for the coating is usually about 1100°-1320° F./590°-715° C.
- the temperature is an important operating parameter because it influences the concentration of the organic compound utilized in the precursor gas mixture.
- the temperatures of the substrate in the float bath section are relatively stable and therefore exhibit little variation at the point of application.
- the preferred substrate temperature range is 1100°-1250° F./590° C.-680° C.
- the heat from the substrate raises the temperature of the precursor gas mixture above the temperature required for coating formation (and when an ester is used as the organic compound above thermal decomposition temperature of the ester).
- the metal deposition reaction may be initiated by the decomposition of the organic oxygen compound.
- titanium tetrachloride is used in combination with an ester having an alkyl group with a ⁇ hydrogen
- the titanium oxide coating then forms on the substrate at decomposition rates that are ten times higher than known coating methods.
- the ribbon passes under the gas distributor beam at a relatively fast rate.
- the metal oxide coating is deposited onto the float glass ribbon as the ribbon passes under the coater.
- the inventors propose the following theory regarding the chemical reaction that may take place when using an ester having an alkyl group with a ⁇ hydrogen.
- the inventors do not wish to limit the invention to just this possible explanation, and therefore offer it merely as an aid to understanding the results of the present inventive process.
- the inventors propose that as the ester decomposes, the carbon-hydrogen bond on one of the ⁇ hydrogens breaks and the hydrogen transfers to the carbonyl group eliminating an alkene and forming a caboxylic acid.
- the hydrolysis reaction simultaneously takes place between the carboxylic acid and the metal tetrachloride leading to the formation of the metal oxide coating on the substrate.
- the resulting article produced in accordance with the present invention comprises a substrate having a titanium oxide or tin oxide coating.
- the coating may be applied directly to the substrate or as a layer in a plurality of coatings on a substrate.
- the rate of deposition of the metal oxide coating is effected by the decomposition rate of the organic oxygen compound.
- the desired metal oxide coating growth rate for a given system is selected by matching a specific organic oxygen compound to the precursor gas mixture temperature and the substrate temperature at the point of application.
- the deposition rate of the titanium oxide coating in the present invention may be ten times greater than rates in known deposition methods.
- the present inventive process permits deposition rates over 130 ⁇ per second with some deposition rates measured well over 300 ⁇ per second.
- the higher deposition rates for titanium oxide yield a coating with a refractive index greater than 2.4.
- the resulting oxide coating contains little residual carbon from the decomposition of the organic oxygen compound, especially when an ester is used.
- Carbon is an undesirable by product of the coating reaction because high levels of carbon in deposition coatings create absorption problems with the coating.
- the concern in using an organic oxygen compound in the coating precursor gas mixture is that decomposition will result in levels of carbon that adversely affect the absorption properties of the finished glass.
- the carbon content in the coatings produced from the method of the present invention showed less than four atomic percent of carbon where measured. This low level of carbon will not significantly affect absorption properties of the coating.
Abstract
A chemical vapor deposition process for laying down a tin or titanium oxide coating on a glass substrate through the use of an organic oxygen-containing compound and the corresponding metal tetrachloride. The organic oxygen compound is preferably an ester having an alkyl group with a β hydrogen in order to obtain a high deposition rate. The resulting article has a tin or titanium oxide coating which can be of substantial thickness because of the high deposition rates attainable with the novel process, and, in the case of titanium oxide coating possesses a desirable refractive index greater than 2.4. The coating growth rates resulting from the method of the present invention may be at least 130 Å per second.
Description
- This application is a continuation of application Ser. No. 08/696,203 filed Aug. 13, 1996, which is hereby incorporated by reference. This application is claiming the benefit under 35 U.S.C. §120 of said application Ser. No. 08/696,203 filed under 35 U.S.C. §111.
- 1. Field of the Invention
- This invention relates to a process for depositing titanium oxide and tin oxide coatings on a flat glass substrate, and the resulting coated glass. More particularly, this invention relates to a chemical vapour deposition process for producing titanium oxide and tin oxide coatings on flat glass using a coating precursor gas mixture comprising the corresponding metal tetrachloride and an organic oxidant.
- 2. Summary of Related Art
- Titanium oxide and tin oxide coatings have been proposed for use on glass containers, for example bottles, to improve the mechanical strength of the containers. It has also been proposed to use both titanium oxide and tin oxide coatings on flat glass to modify the characteristics of the glass for architectural use; titanium oxide coatings deposited under vacuum (by reactive sputtering) are used as components of sputtered multi-layer infrared reflecting coatings, while tin oxide coatings are used, not only as layers of multi-layer sputtered coatings, but also deposited pyrolytically with a dopant as infrared reflecting and/or electroconducting coatings.
- GB patent specification 1,115,342 describes a process for producing glass containers with good inherent strength and good abrasion resistance by spraying the containers, while still hot from the manufacturing process, with a solution or dispersion of stannic chloride (that is, tin tetrachloride) in an organic liquid, isopropyl alcohol being preferred. A small amount of titanium chloride may be incorporated as a modifier. The liquid solution is fed to atomisers, which may be of the pressure jet variety, located on either side of a tunnel over a conveyor for hot glass bottles to produce a ‘mist of liquid reagent’ so that a layer of liquid is formed on all the external surfaces of the bottles where it reacts to form a layer of tin oxide.
- GB patent specification 1,187,784 describes an improvement of the process described in GB patent specification 1,115,342 and apparently more suitable for incorporation into a process for the automatic manufacture of glassware without interfering with the normal running of such process and without requiring additional supervision. The specification proposes to treat glass containers, at high temperature, with a liquid solution of an organic compound of tin “which compound has properties such that upon application of heat it decomposes into two materials, one of which is an organic compound of tin of high decomposition temperature which reacts with the glass surface to produce a diffusion layer of tin oxide within the glass surface, while the other is a volatile compound of tin such that a substantial proportion of vapour of said compound is produced, and subjecting the containers to a heat treatment such that a reaction is caused to occur between the glass at least the surfaces of the containers and the tin compounds”. The material used for treating the glass containers may be provided by reacting tin tetrachloride with organic substances containing carbonyl groups of moderate activity e.g. organic esters of ethyl, n-propyl, isopropyl, n-butyl and isobutyl alcohols with acetic, propionic and butyric acids. The resulting solution may be sprayed, in the presence of ambient atmosphere, on to the hot containers e.g. in the form of a fine mist after they leave the forming machine and before they enter the annealing lehr. GB
patent specification 1 187 783 describes an analogous process to that described in 1 187 784 in which an organic compound of titanium is sprayed on to the hot glass containers in place of the organic compound of tin. The organic titanium compound may be produced, in an analogous manner to the organic compound of tin, by reacting titanium tetrachloride with an organic ester e.g. n-butyl acetate. Again, the resulting solution is sprayed onto the glass in the ambient atmosphere on the container production line. - It has also been proposed to use tin tetrachloride, applied either as a liquid spray or, more recently, in gaseous form, to apply a tin oxide coating to hot flat glass to form an electroconductive, infra-red reflecting coating on the hot glass surface; water is used to hydrolyse the tin tetrachloride and as a source of oxygen for formation of the tin oxide.
- Processes involving use of the reactants in gaseous form (also called CVD or chemical vapour deposition processes) have certain advantages over spray processes for coating flat glass, especially when the reactants can be premixed before application to the glass. Unfortunately, tin tetrachloride reacts readily with water so that previous proposals to use tin tetrachloride and water vapour in gaseous form have usually involved supplying the gases separately to the glass surface and mixing them while in contact with the glass.
- GB patent specification 2 044 137A relates to such a process in which discrete laminar streams of each reactant are formed and projected on to a hot glass substrate by bringing the streams together in reciprocal tangential contact over the glass. Titanium tetrachloride may be used as one of the gaseous reactants, in place of the tin tetrachloride, in order to form a titanium oxide coating. The patent also suggests supplying hydrogen to one of the gas streams to attenuate the violent reaction between the tin tetrachloride and the water vapour. This may be done either by direct addition of gaseous hydrogen, or by the addition of methanol, which is said to react in situ to produce the desired gaseous hydrogen.
- GB patent specification 2 026 454B describes a process in which a coating chamber is positioned over a hot float glass ribbon as it advances from the float bath and successive gaseous streams of (1) preheated nitrogen carrier gas, (2) tin tetrachloride entrained in preheated nitrogen and (3) air, water vapour and hydrofluoric acid are introduced into the coating chamber so they flow along the glass substrate surface being coated as a substantially turbulence free layer. The patent specifies the concentration of water vapour and tin tetrachloride in the gaseous medium over the glass.
- European patent specifications 0 365 239B1 and 0 376 240B1 describe a method and apparatus for depositing a tin oxide coating on a hot glass ribbon. A first gaseous stream of tin tetrachloride in preheated dry air is caused to flow along the surface of the hot ribbon of glass advancing beneath a coating chamber, a second turbulent stream of hydrofluoric acid and steam introduced into the coating chambers at right angles to the plane of the glass and direction of flow of the first gaseous stream, and the combined first and second gas streams drawn through the coating chamber over the glass under turbulent flow conditions. The method and apparatus may also be used to apply a coating of titanium oxide using titanium tetrachloride in place of the tin tetrachloride.
- U.S. Pat. No. 4,590,096 describes a process in which a coating solution comprising a substantially solvent free mixture of an organotin chloride and a reactive organic fluorine compound soluble in or miscible with the organotin chloride is introduced to a preheated carrier gas stream which contains sufficient water vapour that the relative humidity of the gas stream at 18° C. is about 6% to about 100%. The resulting gas stream is passed over a hot glass surface to deposit a fluorine doped tin oxide coating on the hot glass. A wide range of organotin compounds may be used, and the possibility of using tin tetrachloride is mentioned. Similarly, a wide range of organic fluorine compounds, including oxygen containing compounds, for example trifluoroacetic acid and ethyltrifluoroacetate, may be used. Some of the fluorine-containing dopants have limited solubilities in the organotin compounds used, and an optional solubiliser may be used to increase the solubility of the fluorine dopant on the organotin compound; acetic anhydride, ethyl acetate, hexane, methyl isobutyl ketone and butyraldehyde are listed as non-limiting examples of the solubilisers that may be used. However, the U.S. patent, in common with the other patents utilising chemical vapour deposition methods to deposit a metal oxide from a gaseous metal tetrachloride, utilises water vapour as the source of oxygen.
- U.S. Pat. No. 4,751,149 Vijaykumar et al is concerned with deposition of zinc oxide coatings by chemical vapour deposition at low temperature (60° to 350° C., preferably 100° to 200° C.) on heat sensitive photoconductor substrates, and proposes to deposit the zinc oxide coatings from an organozinc compound and an oxidant, which may be an oxygen containing organic compound e.g. an ester, and an inert carrier gas. Although the patent is not entirely clear, it apparently proposes to introduce separate streams of the organozinc compound and oxidant into the deposition chamber, and certainly there is no proposal to pre-mix these components together before delivery to the coating chamber.
- It would be advantageous to provide a method for depositing tin or titanium oxide coatings by a CVD process applied to hot flat glass using a premixture of the corresponding metal tetrachloride as a low cost reactant and a source of oxygen without premature reaction between the metal tetrachloride and oxygen source (previously water) resulting in formation of metal oxide in the coating equipment with consequent problems and inefficiency. It would be particularly advantageous if the method allowed for deposition of the coating at high rates.
- It is an object of the present invention to provide a method for obtaining tin and titanium oxide coatings on a substrate at high deposition rates. High deposition rates are important when coating substrates in a manufacturing process. This is particularly true for an on-line float glass process where the glass ribbon is traveling at a specific line speed and where the ribbon requires a specific coating thickness. The deposition rates obtained with the preferred embodiments of the present invention may be ten times higher than the deposition rates with other known methods for depositing titanium oxide coatings. Especially high deposition rates, particularly for titanium oxide, may be achieved with the present invention using a precursor mixture including an ester with a β hydrogen.
- Another object of the present invention is to provide a method for obtaining a tin oxide or titanium oxide coating wherein the thickness of the coating can be varied based upon the particular organic compound utilized as a source of oxygen in the precursor mixture.
- A further object is to obtain a titanium oxide coating at high deposition rates with a refractive index of at least 2.4.
- A still further object is to produce tin and titanium oxide coatings at high deposition rates using low cost chlorinated precursors.
- In accordance with the present invention, there is provided a chemical vapour deposition process for laying down a tin oxide or titanium oxide coating on a hot glass substrate using a precursor gas mixture containing the corresponding metal tetrachloride and an organic source of oxygen, without the requirement for inclusion of water vapour and the consequent risk of premature reaction.
- The present invention provides a process for depositing a tin oxide or titanium oxide coating on hot flat glass comprising the steps of
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- (a) preparing a precursor gas mixture containing the corresponding metal tetrachloride and an organic oxygen containing compound as a source of oxygen for formation of the metal oxide,
- (b) maintaining said precursor gas mixture at a temperature below the temperature at which the metal tetrachloride reacts to form the metal oxide while delivering the mixture to a coating chamber opening on to the hot glass,
- (c) introducing the precursor gas mixture into the coating chamber whereby the mixture is heated to cause deposition of the corresponding metal oxide incorporating oxygen from the organic compound on to the hot glass surface.
- Surprisingly, a wide range of oxygen-containing organic compounds may be used as the source of oxygen, without requiring the presence of water vapour or gaseous oxygen, including compounds normally considered reducing agents rather than oxidising agents, for example, alcohols. However, the preferred organic compounds are carbonyl compounds, especially esters; and particularly good results have been obtained using esters having an alkyl group with a β hydrogen. The alkyl group with a β hydrogen will normally contain two to ten carbon atoms.
- It is preferred to use organic compounds, especially esters, containing from two to ten carbon atoms, since larger molecules tend to be less volatile and hence less convenient for use in the CVD process of the present invention.
- Particularly preferred esters for use in the practice of the present invention include ethyl formate, ethyl acetate, ethyl propionate, isopropyl formate, isopropyl acetate, n-butyl acetate and t-butyl acetate.
- The method of the present invention is generally practiced in connection with the formation of a continuous glass ribbon substrate, for example during a float glass production process. However, the method of the present invention may be employed in coating other flat glass substrates either on-line or off-line.
- The present invention involves the preparation of a precursor gas mixture which includes tin or titanium tetrachloride and an organic oxygen containing compound; a carrier gas or diluent, for example, nitrogen, air or helium, will normally also be included in the gas mixture. Since thermal decomposition of the organic oxygen containing compound may initiate the metal oxide deposition reaction at a high rate, it is desirable that the precursor mixture be kept at a temperature below the thermal decomposition temperature of the organic oxygen compound to prevent prereaction of the gaseous mixture with formation of the metal oxide.
- The gaseous mixture is maintained at a temperature below that at which it reacts to form the metal oxide, and delivered to a location near a flat glass substrate to be coated, the substrate being at a temperature above said reaction temperature (and above the decomposition temperature of the organic oxygen compound in the precursor gas mixture).
- The precursor gas mixture is thereafter introduced into the vapor space directly over the substrate. The heat from the substrate raises the temperature of the precursor gas above the thermal decomposition temperature of the organic oxygen compound. The organic oxygen compound then decomposes with reaction with the metal tetrachloride producing a metal dioxide coating on the substrate.
- The present invention permits the production of tin and titanium oxide coatings deposited on the hot glass at a high deposition rate e.g. over 130 Å/second and, in preferred embodiments, over 250 Å per second.
- The deposition rate is dependent upon the particular organic oxygen containing compound used, and the concentrations of both the organic oxygen containing compound and the metal chloride, as well as the temperature of the glass. For any particular combination of compounds, the optimum concentrations (and in particular the optimum proportion of organic oxygen containing compound to metal tetrachloride) and flow rates for rapid coating deposition may be determined by simple trial. However, it will be appreciated that the use of higher concentrations of reactants and high gas flow rates is likely to result in a less efficient overall conversion of the reactants into coating, so that the optimum condition for commercial operation may differ from the conditions which provide the highest deposition rates.
- The method of the invention permits the production, at high rates, of titanium oxide and tin oxide coatings on hot flat glass substrates on line during the glass production process. The titanium oxide coatings may be produced with a high refractive index (at least 2.4) permitting the achievement of desired optical effects, especially when used in combination with other coating layers. The tin oxide coatings may be doped, for example with fluorine, increasing their electrical conductivity and infra red reflectivity, and hence their utility as electrical conducting coatings and/or low emissivity coatings in architectural glazing and other applications.
- The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of preferred embodiments when considered in the light of the accompanying drawings in which:
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FIG. 1 is a schematic view of a vertical section of an apparatus for practicing a float glass process which includes gas distributors suitably positioned to enable the practicing of the method of the present invention. -
FIG. 2 is broken sectional view of an article coated according to this invention; and -
FIG. 3 is an enlarged schematic end view of a gas distributor beam suitable for use in practicing the present invention. -
FIG. 4 is an enlarged schematic end view of an alternative gas distributor beam which may be used in practicing the present invention. - Referring now more particularly to the drawings, there is illustrated generally at 10 in
FIG. 1 a float glass installation utilized as a means for practicing the method of the present invention. The float glass apparatus more particularly comprises acanal section 12 along whichmolten glass 14 is delivered from a melting furnace (not shown), to afloat bath section 16 wherein acontinuous glass ribbon 18 is formed in accordance with the well known float process. Theglass ribbon 18 advances from thebath section 16 through anadjacent annealing lehr 20 and acooling section 22. Thecontinuous glass ribbon 18 serves as the substrate upon which the metal oxide coating is deposited in accordance with the present invention. - The
float section 16 includes abottom section 24 within which a bath ofmolten tin 26 is contained, aroof 28,opposite sidewalls 30, and endwalls 32. Theroof 28,side walls 30, and endwalls 32 together define anenclosure 34 in which a non-oxidizing atmosphere is maintained to prevent oxidation of the molten tin. - Additionally, gas distributor beams 64, 66 and 68 are located in the
bath section 16. The gas distributor beams 64 and 66 in the bath section may be employed to apply additional coatings onto the substrate prior to applying the tin or titanium oxide coating by the method of the present invention. The additional coatings may include silicon and silica. - In operation, the
molten glass 14 flows along thecanal 36 beneath a regulatingtweel 38 and downwardly onto the surface of thetin bath 26 in controlled amounts. On the tin bath the molten glass spreads laterally under the influences of gravity and surface tension, as well as certain mechanical influences, and it is advanced across the bath to form theribbon 18. The ribbon is removed over lift out rolls 40 and is thereafter conveyed through theannealing lehr 20 and thecooling section 22 on aligned rolls 42. The application of the coating of the present invention may take place in thefloat bath section 16, or further along the production line, for example in the gap between the float bath and the annealing lehr, or in the annealing lehr. - A suitable non-oxidizing atmosphere, generally nitrogen or a mixture of nitrogen and hydrogen in which nitrogen predominates, is maintained in the
bath enclosure 34 to prevent oxidation of the tin bath. The atmosphere gas is admitted throughconduits 44 operably coupled to adistribution manifold 46. The non-oxidizing gas is introduced at a rate sufficient to compensate for normal losses and maintain a slight positive pressure, on the order of about 0.001 to about 0.01 atmosphere above ambient atmospheric pressure, so as to prevent infiltration of outside atmosphere. Heat for maintaining the desired temperature regime in thetin bath 26 and theenclosure 34 is provided byradiant heaters 48 within the enclosure. The atmosphere within thelehr 20 is typically atmospheric air, while thecooling section 22 is not enclosed and the glass ribbon is open to the ambient atmosphere. Ambient air may be directed against the glass ribbon as byfans 50 in the cooling section. Heaters (not shown) may also be provided within the annealing lehr for causing the temperature of the glass ribbon to be gradually reduced in accordance with a predetermined regime as it is conveyed therethrough. -
FIG. 1 illustrates the use of gas distributor beams 64, 66 and 68 positioned in thefloat bath 16 to deposit the various coatings on the glass ribbon substrate. The gas distributor beam is one form of reactor that can be employed in practicing the process of the present invention. - A conventional configuration for the distributor beams suitable for supplying the precursor materials in accordance with the invention is shown generally schematically at
FIG. 3 . An inverted generally channel-shapedframework 70 formed by spaced inner andouter walls cavities enclosed cavities - The precursor gas mixture is supplied through a fluid cooled
supply conduit 80. Thesupply conduit 80 extends along the distributor beam and admits the gas throughdrop lines 82 spaced along the supply conduit. Thesupply conduit 80 leads to adelivery chamber 84 within aheader 86 carried by the framework. Precursor gases admitted through thedrop lines 82 are discharged from thedelivery chamber 84 through apassageway 88 toward a coating chamber defining a vapour space opening on to the glass where they flow along the surface of theglass 18 in the direction of the arrows inFIG. 3 . -
Baffle plates 90 may be provided within thedelivery chamber 84 for equalizing the flow of precursor materials across the distributor beam to assure that the materials are discharged against theglass 18 in a smooth, laminar, uniform flow entirely across the distributor beam. Spent precursor materials are collected and removed throughexhaust chambers 92 along the sides of the distributor beam. - Various forms of distributor beams used for chemical vapour deposition are suitable for the present method and are known in the prior art.
- One such an alternative distributor beam configuration is illustrated schematically in
FIG. 4 of the drawings. Using this distributor, which is generally designated 100 (and more fully described in European patent EP 0 305 102B), the precursor gas mixture is introduced through agas supply duct 101 where it is cooled by cooling fluid circulated throughducts Gas supply duct 101 opens through anelongated aperture 104 into agas flow restrictor 105. -
Gas flow restrictor 105 is of the kind more fully described in UKpatent specifications GB 1 507 996, and comprises a plurality of metal strips longitudinally crimped in the form of a sine wave and vertically mounted in abutting relationship with one another extending along the length of the distributor. Adjacent crimped metal strips are arranged “out of phase” to define a plurality of vertical channels between them. These vertical channels are of small cross-sectional area relative to the cross-sectional area ofgas supply duct 101, so that the gas is released from thegas flow restrictor 105 at substantially constant pressure along the length of the distributor. - The coating gas is released from the gas flow restrictor into the
inlet side 107 of a substantially U-shaped guide channel generally designated 106 comprisinginlet leg 107,coating chamber 108 which opens onto thehot glass substrate 110 to be coated, andexhaust leg 109, whereby used coating gas is withdrawn from the glass. The rounded corners of the blocks defining the coating channel promote a uniform laminar flow of coating parallel to the glass surface across the glass surface to be coated. - The following examples (in which gas volumes are expressed under standard conditions, i.e. one atmosphere pressure and ambient temperature, unless other stated) which constitute the best mode presently contemplated by the inventor for practicing the invention, are presented solely for the purpose of further illustrating and disclosing the present invention, and are not to be construed as a limitation on, the invention:
- In this series of Examples, a bi-directional coating reactor of the type shown in
FIG. 3 was employed in the laboratory to deposit a titanium oxide coating. - In Examples 1, 2 and 3, the glass was heated on a conveyor furnace to simulate the coating reaction conditions of a float glass process in order to test the method of the present invention. The furnace utilized in-line rollers to convey a glass substrate through a heating zone prior to practicing the method of the present invention. In Example 1, the glass substrate was float glass which had been initially provided with a silica coating. The silica coating was deposited on the float glass through a known chemical vapour deposition process utilizing a precursor of monosilane in an oxygen enriched atmosphere. The silica deposition forms no part of the present invention.
- In accordance with the present invention, a titanium oxide coating was deposited on the silica coated substrate. The substrate was at a temperature of a 1170° F./630° C. and the substrate line speed was at 300 inches/8 metres per minute.
- To deposit the titanium oxide, a precursor gas mixture was developed comprising titanium tetrachloride, ethyl acetate, oxygen, and helium. Helium was included in the precursor mixture as a carrier for the reactants. The precursor mixture was prepared by simultaneously introducing all four gas streams through a manifold system. An in line static mixer was used to ensure a homogeneous precursor mixture. The volume percent composition of the precursor mixture was 0.7% titanium tetrachloride, 17.2% ethyl acetate, 7.2% oxygen, and 74.9% helium, with the flow rates for the components at the manifold being as shown in the accompanying Table 1.
- The temperature of the precursor mixture was kept above 300° F./150° C. in order to prevent the adduct reaction of titanium tetrachloride and ethyl acetate. The precursor temperature was also kept below the 950° F.-1130° F. (510° C.-610° C.) thermal decomposition temperature range of ethyl acetate in order to prevent the mixture from prereacting.
- The precursor mixture was introduced into the reactor just above the moving substrate. The temperature at the precursor tower was 250° F./120° C. The temperature at the reactor face was 350° F./175° C. The higher substrate temperature initiated the thermal decomposition of the ethyl acetate which then resulted in the deposition of the titanium oxide.
- The resulting coated glass was allowed to cool in air and the coating analysed. It was found to be titanium oxide with a carbon content of 2.5-3.5 atomic percent. The thickness of the titanium oxide coating was measured 490 Å and the thickness and growth rate (150 Å per second) are shown in Table 1. The optical properties of the resulting product included an observed Illuminant C transmittance (10° observer) of 62.3% and an observed Illuminant C reflectivity of 35.6%. The extinction coefficient was 0.008 at 550 nm, and the refractive index of the titanium oxide coating was 2.44.
- In Examples 2 and 3 the coating procedure set out in Example 1 was repeated, except that in Example 2 ethyl formate was used as the organic source of oxygen, and in Example 3 isopropanol was used as the organic source of oxygen and uncoated glass (in place of the silicon oxide coated glass of Examples 1 and 2) was used as the substrate. The gas flow rates used and, in the case of Example 2, the thickness and growth rate of the titanium oxide coating produced are shown in Table 1. In Example 3, the isopropanol burned in the reactor leaving only particulate titanium oxide on the glass, the corresponding deposition rate therefore being quoted as 0 Å/second.
- The procedure for Examples 4 and 5 was as used in the previous Examples (the reactor temperature and the substrate being identical to Example 1), except that the substrate was static and not dynamic. The static sample was positioned under the reactor for 10 seconds. Under static conditions, the residence time of the substrate under the reactor is increased from the dynamic conditions by a factor of five.
- In Example 4, methyl acetate was used as the organic source of oxygen, and in Example 5 t-butyl acetate was used; in each case a titanium oxide coating was produced. The gas flow rates, resulting titanium oxide coating thickness and coating growth rates are as shown in Table 1. The relatively slow growth rate achieved using methyl acetate is discussed hereinafter.
TABLE 1 Flow rates (litres/minute) Organic Growth Exam- Titanium oxygen Oxy- He- Thick- te ple tetrachloride compound gen lium ness Å Å/s 1 0.2 4.8 ethyl 2.0 20.9 490 150 acetate 2 0.5 1.6 ethyl 6.0 17.4 800 250 formate 3 0.45 1.5 isopropanol 4.0 15.45 0 0 4 0.5 1.2 methyl 6.0 17.4 <100 <10 formate 5 0.5 0.5 t-butyl 6.0 16.5 1300 130 acetate - A float glass process was used in producing a continuous glass ribbon having a thickness of 0.125 inches/3 mm at a line speed of 434 inches/11 metres per minute. The glass temperature was at 1140° F./615° C. at the desired point of application in the float bath section of a titanium oxide coating using a coating reactor similar to that shown in
FIG. 3 . The temperature at the precursor tower was 400° F./205° C. and the temperature at the reactor face was 500° F./260° C. Prior to practicing the method of the present invention, a silica coating was deposited on the glass substrate in the float bath section at a thickness of about 339 Å. The same chemical vapor deposition process as described in Example 1 was used to deposit the silica coating. The silica deposition forms no part of the present invention. - The precursor gas mixture was developed comprising titanium tetrachloride and ethyl acetate in a helium carrier gas. Oxygen was not used in the precursor as result of earlier Examples indicated that the coating reaction was not sensitive to the oxygen concentration. The precursor mixture was prepared by simultaneously introducing the three components through a manifold system. The volume percent composition of the precursor mixture was 0.6% titanium tetrachloride, 1.8% ethyl acetate, and 97.5% helium. The flow rates for the components were 480.0 l/m of helium, 3.0 l/m of titanium tetrachloride, 9.2. l/m of ethyl acetate. The total flow rate for the precursor mixture was 492.2 l/m.
- The resulting titanium oxide coating was 684 Å thick. The carbon content of the coating was less than 2 atomic percent. The growth rate of the coating was 309 Å per second.
- The same procedure carried out Example 6 was utilized in this Example. The substrate comprised coatings of silicon and then silica over the glass substrate. The coatings were deposited by a known chemical vapor deposition process in the float bath section. The silicon coating was deposited by CVD from monosilane with a non-oxidizing carrier gas. The silica coating was then deposited onto the silicon coating through the use of the same procedure as described in Example 1.
- The precursor for the titanium oxide coating included titanium tetrachloride and ethyl acetate in a helium carrier gas. The volume percent composition of the precursor was 0.5% titanium tetrachloride, 1.9% ethyl acetate, and 97.6% helium. The corresponding flow rates for the components were 480.0 l/m of helium, 2.4 l/m of titanium tetrachloride, 9.2 l/m of ethyl acetate. The total flow rate for the precursor mixture was 491.6 1/m.
- The resulting
coated article 52 is illustrated inFIG. 2 . Theglass substrate 54 is depicted with a stack ofmultiple coatings 56. The coatings comprise a layer ofsilicon 58, a layer ofsilica 60, then atitanium oxide coating 62 on top of the article. The titanium oxide coating on the resulting article had a thickness of 836 Å. The optical properties of the resulting coating stack included an observed Illuminant C transmittance of 13.1% and an observed Illuminant C reflectivity of 82.5%. The growth rate of the titanium oxide coating was 378 Å per second. - In this series of Examples, a static coater was used in the laboratory to apply a tin oxide coating on to a float glass substrate carrying a colour suppressing silicon oxide layer produced as described in European patent EP 0 275 662B.
- The float glass to be coated was supported on a nickel block in a reactor vessel and the block heated from below by electric heating elements to provide a glass temperature of 1085° F./585° C. A flat graphite plate was mounted approximately 0.4 inches/10 mm above the glass and parallel thereto to provide a gas flow path 0.4 inches/10 mm deep between the glass surface bearing the silicon oxide layer and the plate.
- A precursor gas mixture containing tin tetrachloride and an organic source of oxygen, in air and a small proportion of additional nitrogen as carrier gas, was delivered through a gas line maintained at a temperature of 435° F.±25° F./225° C.±15° C. and provided with a fish tail nozzle opening on to the gas flow path over the hot glass in a general direction parallel to the glass surface. The total carrier gas flow rate was 13 m3/hour. The flow rates of the tin tetrachloride, and the nature and flow rates of the organic compound used, were as shown in the accompanying Table 2. In Examples 9 and 11, small amounts of 40% hydrogen fluoride were incorporated in the-precursor gas mixture to dope the resulting tin oxide coating with fluorine, as shown in the Table.
- The gas flow containing the reactant gases was applied for approximately 8 seconds, and the coating apparatus and coated glass then allowed to cool under a flow of air at 345° F./225° C. On dismantling the coating apparatus, the delivery gas line, nozzle and plate defining the gas flow path over the glass found to be free, in each case, from deposit, indicating an absence of undesirable prereaction. In each case, the glass had a tin oxide coating applied over the silicon oxide, the thickness of the coating varying with distance from the fishtail nozzle. The maximum thickness and corresponding growth rate for each precursor gas mixture used is shown in Table 2. The emissivity, resistivity and haze of the samples producing using hydrogen fluoride to incorporate a fluorine dopant (Examples 9 and 11) were measured and the results reported in Table 2.
- This series of Examples shows that an organic source of oxygen can be used as part of a premixed precursor gas mixture comprising tin tetrachloride to deposit a tin oxide coating without significant undesirable prereaction detrimentally affecting the coating process e.g. by deposition of tin oxide in the gas supply ducts. Moreover, if desired, a source of dopant, such as hydrogen fluoride, may be incorporated in the gaseous premixture to reduce the emissivity and resistivity of the coating while continuing to avoid significant detrimental prereaction.
TABLE 2 Precursor Gas Mixture Organic Oxygen Source SnCl4 Flow 40% HF Max tin Max growth Flow Rate Rate Flow Rate oxide rate Resistivity Example (ml/min) Compound (ml/min) (ml/min) thickness Å Å/second Emissivity ohm/cm Haze 8 12 ethyl acetate 10 — 2750 344 — — — 9 12 ethyl acetate 10 1 2680 335 0.25 5.3 × 10−4 0.4% 10 12 butyl acetate 13.4 — 3460 432 — — — 11 12 butyl acetate 13.4 1.3 2880 360 0.25 6.9 × 10−4 0.6% 12 6 isopropyl 120 — 2284 262 — — — alcohol 13 17 trifluoracetic 16.2 — 2840 335 — — — acid - In this Example, a coating distributor as illustrated schematically in
FIG. 4 was used in a float bath to apply a coating of tin oxide by a method in accordance with the invention. The ribbon speed was approximately 233 inches per minute/350 minutes per hour and the glass thickness was 0.05 inches/1.2 mm. The glass temperature was approximately 1170° F./630° C. The temperature of thegas supply duct 101 which served as a primary gas mixing chamber was maintained at 300° F./150° C. and the ‘static’waffle gas distributor 105 was approximately 645° F./340° C. The tin tetrachloride and butyl acetate vapors were delivered by bubbling nitrogen through the liquids maintained at 175° F./80° C. in bubblers and, hence, through separate heated conduits togas supply duct 101. The vapors mixed at the primary chamber, passed through the waffle pack gas distributor, and then under laminar flow conditions throughU-shaped guide channel 106 comprisingcoating chamber 108 opening on to the hot glass ribbon. - The flow rates used were sufficient to obtain tin tetrachloride:butyl acetate molar ratios of between 1:1 and 1:5. The trial was carried out for 5 hours. On dismantling the coater it was discovered that the cooled surfaces and the associated conduits were over 90% free of deposits, thus showing that tin tetrachloride and butyl acetate used for producing a tin dioxide coating on glass can be premixed with one another without substantial prereaction. A thin tin oxide coating was obtained on the glass ribbon.
- It will be appreciated that various changes and modifications can be made from the specific details of the invention as incorporated in the foregoing Examples without departing from the spirit and scope thereof as defined in the appended claims.
- In its essential details, the invention is a continuous chemical vapor deposition process for laying down tin oxide and titanium oxide coatings onto a glass substrate at high deposition rates through the use of the corresponding metal tetrachloride and an organic compound used as a source of oxygen in a preformed precursor gas mixture.
- The metal tetrachlorides are preferred sources of the respective metals because of the availability and cost of the raw material.
- It has been found, especially when depositing titanium oxide coatings from titanium tetrachloride, that, in order to form the metal oxide at the optimum deposition rates, it is desirable to use an organic oxygen containing compound which is an ester, particularly an ester in which the group derived from the alcohol is an alkyl group with a β hydrogen. Additionally, the decomposition temperature of the ester should not be greater than the reaction temperature of the coating precursor gas mixture at the desired point of application. Esters utilized in the precursor gas mixture that have a β hydrogen and appropriate decomposition temperatures will deposit the coatings at high deposition rates. The preferred group of esters used in practicing the present invention includes the group consisting of ethyl formate, ethyl acetate, ethyl propionate, isopropyl formate, isopropyl acetate, n-butyl acetate, and t-butyl acetate.
- In general an ester decomposes in a continuous fashion over a given temperature range. In the present invention, the thermal decomposition temperature of the ester is defined as the temperature at which the unimolecular decomposition rate constant of the ester is 0.01/sec. The unimolecular decomposition rate constants of common esters such as ethyl acetate and t-butyl acetate are well known and can be found in the chemical literature. For ethyl acetate and t-butyl acetate, the thermal decomposition temperatures using the above definition are 935 and 650° Fahrenheit (500° C. and 344° C.), respectively. One skilled in the art will recognize that the choice of ester and specific deposition temperature employed will determine the optimum coating growth rate. Reaction temperatures below the defined thermal decomposition temperature, but within the decomposition range of the selected ester, will result in lower coating growth rates.
- In accordance with the present invention, the alkyl group of an ester used in the coating precursor gas mixture may be a carbon compound having a range of 2-10 carbon atoms. The lower limit of the range is dictated by the β hydrogen requirement on the alkyl group. The upper limit is to avoid flammability and volatility issues that arise when the alkyl group contains more than ten carbon atoms.
- In practicing the method of the present invention, a manifold may be used to connect and regulate the individual gas streams to formulate the coating precursor gas mixture. A common delivery line may be used to deliver the precursor gas mixture from the manifold to the gas beam distributor. An in line static mixer may be used in the delivery line to ensure a homogeneous gas mixture. Additionally, the baffles in the gas distributor beam, illustrated in
FIG. 3 , or a gas flow restrictor as described with reference toFIG. 4 , may provide further mixing of the precursor gas at the reactor stage. - In many of the Examples, oxygen was included in the coating precursor gas mixture. However, the deposition rate of the metal oxide coating was not sensitive to the oxygen concentrations, and no oxygen gas was used in Examples 6 or 7 showing the inclusion of oxygen to be unnecessary.
- The concentration of the reactive components of the coating precursor gas mixture may be selected to obtain the optimum coating growth rate. The concentration of metal tetrachloride is generally 0.1 to 5.0 percent by volume in the precursor gas mixture. The concentration of metal tetrachloride is based upon the amount of metal needed to provide the desired coating thickness in the available residence time. Thus the metal tetrachloride concentration is adjusted according to process variables, such as the line speed of the ribbon in a float glass process.
- The concentration of the organic oxygen compound in the coating precursor gas mixture is generally one to five times the concentration of the metal tetrachloride, being selected within this range based upon the deposition temperature. When using an ester, lower deposition temperatures will result in slower ester decomposition rates and therefore, will require greater concentrations of the ester to react with the metal tetrachloride. In Examples 6 and 7, the optimum concentration of the ethyl. acetate in the precursor gas mixture is 1 to 3 times the concentration of the titanium tetrachloride. Concentrations above or below the optimum range will produce metal oxide coatings at lower coating growth rates.
- The temperature of the precursor gas mixture is critical for control of the reaction, in particular to avoid undesirable pre-reaction or adduct formation resulting in formation of an involatile product in the precursor lines. In one preferred embodiment, especially applicable when using an ester, the temperature is maintained above 300° F./150° C. in the precursor gas lines. The precursor gas mixture is also preferably kept below the thermal decomposition temperature of the organic oxygen. compound to prevent prereaction of the mixture.
- The present inventive process utilizes the heat from the substrate to initialize the coating reaction. In on-line situations, such as the float glass process, the substrate is formed at extremely high temperatures. Therefore, the method of the present invention may be applied at a point in the float glass process where the substrate temperature is lowered but is still above the temperature at which the coating is formed (and preferably after the glass ribbon has substantially finished stretching i.e. below 1380° F./750° C.). Off-line applications of the present invention will require heating the substrate to a temperature above the decomposition temperature of the ester.
- In practicing the method of the present invention in the float glass process, the preferred point of application is in the float bath section. The temperature range at the point of application for the coating is usually about 1100°-1320° F./590°-715° C. The temperature is an important operating parameter because it influences the concentration of the organic compound utilized in the precursor gas mixture. The temperatures of the substrate in the float bath section are relatively stable and therefore exhibit little variation at the point of application. In examples 6 and 7 using ethyl acetate, the preferred substrate temperature range is 1100°-1250° F./590° C.-680° C.
- The heat from the substrate raises the temperature of the precursor gas mixture above the temperature required for coating formation (and when an ester is used as the organic compound above thermal decomposition temperature of the ester). The metal deposition reaction may be initiated by the decomposition of the organic oxygen compound. When titanium tetrachloride is used in combination with an ester having an alkyl group with a β hydrogen, the titanium oxide coating then forms on the substrate at decomposition rates that are ten times higher than known coating methods. In the on-line application with a float glass ribbon process, the ribbon passes under the gas distributor beam at a relatively fast rate. The metal oxide coating is deposited onto the float glass ribbon as the ribbon passes under the coater.
- The inventors propose the following theory regarding the chemical reaction that may take place when using an ester having an alkyl group with a β hydrogen. However, the inventors do not wish to limit the invention to just this possible explanation, and therefore offer it merely as an aid to understanding the results of the present inventive process.
- The inventors propose that as the ester decomposes, the carbon-hydrogen bond on one of the β hydrogens breaks and the hydrogen transfers to the carbonyl group eliminating an alkene and forming a caboxylic acid. The hydrolysis reaction simultaneously takes place between the carboxylic acid and the metal tetrachloride leading to the formation of the metal oxide coating on the substrate.
- In general, the resulting article produced in accordance with the present invention comprises a substrate having a titanium oxide or tin oxide coating. The coating may be applied directly to the substrate or as a layer in a plurality of coatings on a substrate. The rate of deposition of the metal oxide coating is effected by the decomposition rate of the organic oxygen compound. At constant reaction temperatures different organic oxygen compounds will provide different coating growth rates because of the difference in the decomposition temperatures. Therefore, the desired metal oxide coating growth rate for a given system is selected by matching a specific organic oxygen compound to the precursor gas mixture temperature and the substrate temperature at the point of application.
- The deposition rate of the titanium oxide coating in the present invention may be ten times greater than rates in known deposition methods. The present inventive process permits deposition rates over 130 Å per second with some deposition rates measured well over 300 Å per second. The higher deposition rates for titanium oxide yield a coating with a refractive index greater than 2.4.
- In the present invention, the resulting oxide coating contains little residual carbon from the decomposition of the organic oxygen compound, especially when an ester is used. Carbon is an undesirable by product of the coating reaction because high levels of carbon in deposition coatings create absorption problems with the coating. The concern in using an organic oxygen compound in the coating precursor gas mixture is that decomposition will result in levels of carbon that adversely affect the absorption properties of the finished glass. The carbon content in the coatings produced from the method of the present invention showed less than four atomic percent of carbon where measured. This low level of carbon will not significantly affect absorption properties of the coating.
- It is to be understood that the forms of the invention herewith shown and described are to be taken as illustrative embodiments only of the same, and that various changes in the shape, size and arrangement of parts, as well as various procedural changes, may be resorted to without departing from the spirit of the invention.
Claims (14)
1-32. (canceled)
33. A titanium dioxide photocatalyst structure comprising:
a transparent glass substrate having first and second opposing surfaces, said transparent glass substrate containing alkaline ingredients therein, the first surface of said substrate receiving light from an external light source;
a titanium dioxide film having first and second opposing surfaces, a light transmittance of said titanium dioxide film being at least 50% for light having a wavelength of 550 nm, the first surface of said titanium dioxide film being formed on the second surface of said substrate, whereby light transmitted from said external source through the first and second opposing surfaces of said substrate and through the first surface of said titanium dioxide film to the second surface thereof causes photocatalytic activity to be generated on the second surface of said titanium dioxide film; and
a transparent precoat film interposed between the second surface of said substrate and the first surface of said titanium dioxide film.
34. The titanium dioxide photocatalyst structure according to claim 33 , wherein said transparent precoat film has a thickness of 0.02 μm to 0.2 μm.
35. The titanium dioxide photocatalyst structure according to claim 34 , wherein said precoat film is composed of SiO2.
36. A titanium dioxide photocatalyst structure comprising:
a transparent substrate;
a titanium dioxide film formed on said substrate, said titanium dioxide film having photocatalytic activity and a light transmittance of at least 50% for light having a wavelength of 550 nm; and
a transparent precoat film disposed between the transparent substrate and the titanium dioxide film.
37. The titanium dioxide photocatalyst structure according to claim 36 , wherein the precoat film has a thickness of 0.02 μm to 0.2 μm.
38. The titanium dioxide photocatalyst structure according to claim 36 , wherein the precoat film is composed of SiO2.
39. A method for producing a titanium dioxide photocatalyst structure according to claim 36 comprising a producing process which includes the step of forming the titanium dioxide film on the transparent substrate by a method selected from the group consisting of a pyro-sol method, a dipping method, a printing method and a CVD method.
40. A titanium dioxide photocatalyst structure comprising:
a transparent substrate;
a titanium dioxide film formed on said substrate, said titanium dioxide film having a thickness of 0.1 μm to 5 μm, photocatalytic activity and a light transmittance of at least 50% for light having a wavelength of 550 nm; and
a transparent precoat film disposed between the transparent substrate and the titanium dioxide film.
41. The titanium dioxide photocatalyst structure according to claim 40 , wherein the precoat film has a thickness of 0.02 μm to 0.2 μm.
42. The titanium dioxide photocatalyst structure according to claim 40 , wherein the precoat film is composed of SiO2.
43. A titanium dioxide photocatalyst structure comprising:
a transparent substrate;
a titanium dioxide film, containing an anatase crystal, formed on said substrate, said titanium dioxide film having photocatalytic activity and a light transmittance of at least 50% for light having a wavelength of 550 nm; and
a transparent precoat film disposed between the transparent substrate and the titanium dioxide film.
44. The titanium dioxide photocatalyst structure according to claim 43 , wherein the precoat film has a thickness of 0.02 μm to 0.2 μm.
45. The titanium dioxide photocatalyst structure according to claim 43 , wherein the precoat film is composed of SiO2.
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US11/447,862 US20060228476A1 (en) | 1996-08-13 | 2006-06-07 | Method for depositing tin oxide and titanium oxide coatings on flat glass and the resulting coated glass |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
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US19953998A | 1998-11-25 | 1998-11-25 | |
US66218100A | 2000-09-14 | 2000-09-14 | |
US11/447,862 US20060228476A1 (en) | 1996-08-13 | 2006-06-07 | Method for depositing tin oxide and titanium oxide coatings on flat glass and the resulting coated glass |
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US66218100A Division | 1996-08-13 | 2000-09-14 |
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US11/447,862 Abandoned US20060228476A1 (en) | 1996-08-13 | 2006-06-07 | Method for depositing tin oxide and titanium oxide coatings on flat glass and the resulting coated glass |
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US09/657,275 Expired - Lifetime US6238738B1 (en) | 1996-08-13 | 2000-09-07 | Method for depositing titanium oxide coatings on flat glass |
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EP2780108A4 (en) * | 2011-11-16 | 2015-08-19 | Cristal Usa Inc | Neutral, stable and transparent photocatalytic titanium dioxide sols |
US9352299B2 (en) | 2011-11-16 | 2016-05-31 | Cristal Usa Inc. | Neutral, stable and transparent photocatalytic titanium dioxide sols |
US9938619B2 (en) | 2014-09-11 | 2018-04-10 | Pilkington Group Limited | Chemical vapor deposition process for depositing a titanium oxide coating |
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US11325859B2 (en) | 2016-11-17 | 2022-05-10 | Cardinal Cg Company | Static-dissipative coating technology |
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