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
  • C03C17/25—Oxides by deposition from the liquid phase
• • 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
  • C03C2217/213—SiO2
• • 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
  • C03C2218/11—Deposition methods from solutions or suspensions
  • C03C2218/113—Deposition methods from solutions or suspensions by sol-gel processes

Definitions

• Tempered safety glass provided with a smudge-proof, porous SiO 2 anti-reflective layer and process for its production
• the invention relates to a toughened safety glass provided with a smudge-proof, porous Si0 2 anti-reflective layer, and to a method for its production.
• the porous Si0 2 anti-reflection coating shows excellent adhesion and it increases the transmission of visible or other electromagnetic radiation while preventing or minimizing unwanted reflections.
• the safety glass according to the invention is used, for example, for covers for solar collectors and photovoltaic cells. But it can also be used for automotive windshields or for building glazing.
• the conditions for destructive interference only apply to a certain wavelength and a certain angle of incidence.
• the refractive index of the layer determines the height of the reflection minimum. For the optimal anti-reflective coating of glass, it must be 1 .22 in order to achieve a reflection of almost zero at the wavelength ⁇ . This low refractive index cannot be achieved with dense layers.
• the development of single layers on glass with such a low refractive index started 50 years ago.
• the methods described since then can be divided into three groups.
• the first relates to the direct etching of glass, the second porous coatings and the third is a combination of the two, i.e. layers with low porosity are subsequently etched.
• Porous layers which are produced by etching glass, are characterized in principle by very good optical results.
• this is only suitable Glasses which undergo phase separation, such as, for example, borosilicate glass with the composition 55-82% SiO 2 , 12-30% B 2 O 3 , 2-12% alkali metal oxides and 0-7% Al 2 O 3 .
• the complex etching processes and the use of questionable acids such as NH 4 F-HF are disadvantageous.
• toughened safety glass cannot be retrofitted with a smudge-proof, ie well-adhering Si0 2 anti-reflective layer, because toughened safety glass cannot be heated to temperatures of 500 ° C after coating without the glass relaxing again and its properties as Safety glass loses. Such high temperatures are required to give the Si0 2 layer good adhesion to the glass substrate.
• a tempered safety glass which is provided with a smudge-proof, well-adhering, porous and sinter-stable Si0 2 anti-reflective layer.
• the safety glass according to the invention is obtained by coating a glass customary for the production of toughened safety glass with a colloidally disperse solution, drying the coated glass and heating it to temperatures of at least 630 ° C. to remove the organic constituents and tempering and then thermally quenching.
• the colloidally disperse solution was obtained by hydrolytic condensation of silicon compounds of the general formula I
• radicals are the same or different and R is an organic radical having 1 to 10 carbon atoms, which can be interrupted by oxygen and / or sulfur atoms and / or by amino groups
• X for hydrogen, halogen, hydroxy , Alkoxy, acyloxy, alkylcarbonyl, alkoxycarbonyl or NR ' 2 , where R' is hydrogen, alkyl or aryl, and a is 0, 1 or 2.
• Monomeric silicon compounds of the formula I or precondensates derived therefrom can be used to prepare the colloidally disperse solution.
• the hydrolytic condensation takes place by the action of water or moisture and optionally in the presence of a catalyst and / or a solvent.
• the colloidally disperse solution also contains one or more organic polymers which carry one or more OH and / or NH groups.
• the average molecular weight of these polymers is between 200 and 500,000, and the molar ratio of polymer to organically modified silane of the formula I is between 0.1 mmol / mol silane and 100 mmol / mol silane.
• alkyl radicals in general formula I are e.g. straight-chain, branched or cyclic radicals with 1 to 10 carbon atoms and preferably lower alkyl radicals with 1 to 6, particularly preferably with 1 to 4 carbon atoms. Specific examples are methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, n-pentyl, n-hexyl, cyclohexyl, 2-ethylhexyl, dodecyl and octadecyl .
• Preferred aryl radicals in general formula I are e.g. Phenyl, biphenyl and naphthyl.
• the alkoxy, acyloxy, alkylcarbonyl, alkoxycarbonyl, alkylamino and dialkylamino radicals are preferably derived from the above-mentioned alkyl and aryl radicals.
• the radicals mentioned can optionally carry one or more substituents, for example halogen, alkyl, hydroxyalkyl, alkoxy, aryl, aryloxy, alkylcarbonyl, alkoxycarbonyl, furfuryl, tetrahydrofurfuryl, amino, monoalkylamino, dialkylamino, trialkylammonium, amido, hydroxy, formyl, carboxy, mercapto, Cyano, isocyanate, nitro, epoxy, S0 3 H or P0 4 H 2 .
• halogens fluorine, chlorine and bromine and especially chlorine are preferred.
• silanes of the general formula I can be hydrolyzed and condensed via the radicals X. Via these hydrolytically condensable groups, an inorganic network with Si-O-Si units.
• silicon compounds of the general formula SiX are used.
• specific examples of such silanes are SiCl 4 , HSiCl 3 , Si (OCH 3 ) 4 , Si (OOCCH 3 ) 4 and Si (OC 2 H 5 ) 4 , tetraalkoxysilanes being particularly preferred and Si (OCH 3 ) 4 (TMOS) is very particularly preferred.
• Silanes of the general formula! are either commercially available or can be produced by methods as described in "Chemistry and Technology of Silicones” (W. Noll, Verlag Chemie, Weinheim / Bergstrasse, 1968). They can be used either as such or in precondensed form.
• the silanes of the general formula I are hydrolyzed and polycondensed.
• the polycondensation is preferably carried out by the sol-gel process, as described, for example, in DE-Al 2758414, 2758415, 301 1761, 382671 5 and 3835968.
• the hydrolytic condensation can be carried out, for example, by adding the required water directly to the silicon compounds to be hydrolyzed, which are present either as such or dissolved in a suitable solvent, at room temperature or with gentle cooling (preferably with stirring and in the presence of a Hydrolysis and condensation catalyst) and the resulting mixture then stirred for some time (one to several hours).
• the hydrolysis is generally carried out at temperatures between -20 and 130 ° C, preferably between 0 and 30 ° C or the boiling point of the solvent used.
• the best way of adding water depends primarily on the reactivity of the starting compounds used.
• the dissolved starting compounds can slowly be added dropwise to an excess of water, or water can be added in one portion or in portions to the starting compounds, which may be dissolved. It may also be useful not to add the water as such, but to add it to the reaction system with the aid of water-containing organic or inorganic systems.
• the water can also be added via a chemical reaction in which water is released in the course of the reaction. Examples of this are esterifications.
• ketones preferably lower dialkyl ketones, such as acetone or methyl isobutyl ketone, ethers, preferably lower dialkyl ethers such as diethyl ether or dibutyl ether, THF, amides, Esters, especially ethyl acetate, dimethylformamide, amines, especially triethylamine, and mixtures thereof.
• alcohols are used as solvents, preferably ethanol, i-propanol, n-propanol, 1-methoxy-2-propanol or 2-methoxyethanol and very particularly preferably methanol.
• the amount of solvent used depends on the amount and solubility of the (partially) condensed silicon compounds and the polymers used. It is crucial that the coating solution according to the invention is in colloidally disperse form.
• an alcohol can act as a solvent as a moderator for the hydrolysis and condensation, and the reactivity of the system can be controlled and adapted to the requirements of the respective application.
• the starting compounds do not necessarily all have to be present at the start of the hydrolysis (polycondensation), but in certain cases it can even prove advantageous if only some of these compounds is first brought into contact with water and later the remaining compounds are added.
• the water can be added all at once or in several stages, e.g. in three stages.
• the first stage e.g. one tenth to one twentieth of the amount of water required for the hydrolysis are added.
• a fifth to a tenth of the required amount of water can be added, and after a further brief stirring, the rest can finally be added.
• the condensation time depends on the respective starting components and their proportions, the catalyst used, the reaction temperature, etc. In general, the polycondensation is carried out at normal pressure, but it can also be carried out at elevated or reduced pressure.
• the coating solution contains one or more organic polymers in colloidally dispersed dissolved form. These polymers have OH and / or NH groups and the average molecular masses are between 200 and 500,000, the molar ratio of polymer to organically modified silane being 0.1 mmol / mol silane to 100 mmol / mol silane.
• the polymers added according to the invention contain OH, NH or SH groups, via which there is an interaction with the inorganic network, which was built up by the hydrolytic condensation of the silicon compounds. This interaction results in a uniform distribution of the organic polymers in the polycondensate, which then leads to a particularly homogeneous porosity of the antireflection coating.
• the organic polymers can be added either at the beginning of the hydrolytic condensation, during or after the end thereof. Without restricting generality, specific examples of such polymers are polyhydrazides
• the average molecular weight of the organic polymers is between 500 and 50,000.
• the size and amount of the organic polymer added allow the porosity and thus the refractive index of the antireflection coating to be specifically controlled and adapted to the requirements of the particular application. For example, an increase in the pore volume results in a decrease in the refractive index.
• the safety glass according to the invention shows refractive indices which are between 1.22 and 1.44, preferably between 1.22 and 1.33.
• the coating specialist can do just a few
• the layer thickness of the coating allows its anti-reflection behavior to be specifically adapted to the wavelength of the incident radiation.
• the coating solution has a pH of> 7.
• base-reacting polymers such as, for example, polyethyleneimines.
• the coating solution is applied to the glass surfaces to be antireflection coated and dried by customary methods. All types of glass can be used, which are usually used for the production of thermally toughened safety glass. It goes without saying that, depending on the desired layer thickness, the viscosity of the coating solution and the parameters of the coating process, e.g. the speed of immersion and extraction of the glass to be coated in or from the coating solution must be coordinated. However, this is part of the expertise of every coating specialist.
• the coated glass is then dried and heated to temperatures of at least 630 ° C. This removes the organic constituents of the coating and results in a porous Si0 2 framework. At temperatures of at least 630 ° C, the porous Si0 2 framework has excellent adhesion to the glass surface.
• the glass is then thermally tempered by quenching so that it acquires the properties of a safety glass.
• Another advantage of the method according to the invention is that smudge-proof antireflection coatings can be obtained within only 3 minutes at temperatures between 630 and 700 ° C.
• the method according to the invention is preferably used when temperatures of at least 700 ° C. are required for the thermal tempering of the glass, and particularly preferably at temperatures of at least 800 ° C.
• the coated and heated glass is subjected to a shaping process before thermal quenching. It was surprisingly found that the any damage to the porous layer that occurs in this process is negligible.
• the coated and heated glass can be bent before quenching. In this way, for example, car windshields or building glazing are available.
• the anti-reflective coating according to the invention can e.g. can be used for anti-reflective treatment and to increase the transmission of solar systems.
• the safety glass according to the invention finds e.g. Application in photovoltaic cells and in solar collectors, as automotive windshields and as building glazing.
• Example 1 First, a coating solution according to the embodiment of DE 196 42 419 AI is made. Eight pebbles of silica glass are immersed in this solution and pulled out at a constant speed. Then these eight slices are each exposed to different temperatures between 500 and 1200 ° C for 15 minutes and then measured spectrophotometrically. The results are shown in Figure 1. For samples that were exposed to temperatures between 500 and 1000 ° C, reflection minima of less than 0.5% are measured. Surprisingly, the resulting residual reflection even decreased up to a temperature of 1000 ° C instead of increasing. The porous SiO 2 layer only densifies above 1000 ° C. These antireflection layers only sinter in a temperature range that is 500 ° C above that known from the literature.
• a glass pane with an area of 1 m 2 is immersed in the solution from Example 1 and pulled out at a constant speed.
• the pane is then vented at room temperature for about 5 minutes before it leaves the Coating is taken and passed through a zone oven within 3 minutes.
• the coated glass is brought to temperatures of over 600 ° C and then quenched in an air shower.
• safety glass is obtained which is equipped with an anti-reflective layer.
• a solar transmission of 96% is achieved.
• the visual transmission increases from 91.5% in the uncoated state to over 95.5% in the coated state.

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• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Surface Treatment Of Glass (AREA)
• Glass Compositions (AREA)
• Surface Treatment Of Optical Elements (AREA)

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• 1999
  • 1999-04-26 DE DE19918811A patent/DE19918811A1/de not_active Ceased
• 2000
  • 2000-04-22 ES ES00940146T patent/ES2261209T3/es not_active Expired - Lifetime
  • 2000-04-22 AU AU55204/00A patent/AU5520400A/en not_active Abandoned
  • 2000-04-22 DE DE50012487T patent/DE50012487D1/de not_active Expired - Lifetime
  • 2000-04-22 AT AT00940146T patent/ATE321740T1/de active
  • 2000-04-22 EP EP00940146A patent/EP1181256B1/de not_active Expired - Lifetime
  • 2000-04-22 WO PCT/DE2000/001301 patent/WO2000064830A1/de not_active Ceased
  • 2000-04-22 JP JP2000613785A patent/JP4278875B2/ja not_active Expired - Fee Related

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