Patent Application
20110305899
The invention relates to a method for producing a reflection-reduced pane, a pane produced using the method according to the invention, and its use.
In addition to the high optical transparency desired in many cases, many panes also have strong light reflections. When light strikes an interface between media with different refractive indices, part of the incident light is reflected. Depending on the light source, wavelength, and the angle of incidence, these reflections can be significant. For example, reflections of sunlight on buildings or preceding vehicles can blind other road users. Light reflections are also usually undesirable in photovoltaics since they reduce the amount of light on the surface of photocells. With the reduced amount of light, the efficiency of the solar cell is also reduced in many cases.
Basically, many methods are applied in practice to reduce the reflection of panes. The reflection reduction of panes is based in many cases on the creation of a porous, structured layer on the glass surface. This porous structured layer can be created by etching with an appropriate acid or base. Another possibility is the creation of a porous SiO2 layer by deposition of SiO2 on the glass surface, for example, in a sol-gel process. In principle, combinations of the two processes of etching and deposition are also possible.
Because of the mechanical stability of glass, the methods for reflection reduction are usually not possible until after the tempering and bending processes. Thus, usually only customized pane segments and, consequently, a limited number of panes can be etched at the same time.
U.S. Pat. No. 2,486,431 A discloses a method for creating a low-glare glass surface. The glass surface is etched with an H2SiF6 solution. Depending on the duration of the etching process, the glass surface is removed in varying degrees and, thus, the optical properties of the surface are adapted and varied.
DE 822 714 B discloses a method for producing a reflection-reducing film on the surface of a glass object. For this, the glass object is dipped into a solution of H2SiF6 and colloidally dissolved SiO2. Depending on the F−and SiO2 concentration, the surface of the pane is removed (etched) and/or built up.
U.S. Pat. No. 4,019,884 A discloses a method for producing a reflection-reducing layer on a glass substrate. The method includes heating at a temperature of 630° C. to 660° C. The glass is then etched in aqueous hydrofluoric acid.
DE 196 42 419 A1 discloses a method for producing an antireflection coating. In the method, an organic silicon compound is applied to the glass surface in a sol-gel process. A hydrophilic, colloidally dissolved polymer or a solvent are preferably added as a catalyst.
DE 199 18 811 A1 discloses a tempered safety glass with a smudge-proof, porous SiO2 antireflective layer. The production of the safety glass is carried out in a first step by coating the glass with a colloidally dispersed solution. The glass of the coated pane is heated to at least 600° C. and then thermally quenched.
The object of the invention is to provide a method for etching and tempering panes that enables time and cost effective etching of large-area panes before the tempering process.
The object of the present invention is accomplished according to the invention by a method for producing a reflection reduced pane, a pane obtained with the method, and its use according to the independent claims 1, 7, and 14. Preferred embodiments emerge from the subclaims.
The method for producing a reflection-reduced pane comprises in a first step the etching of a pane. The pane preferably contains glass, particularly preferably flat glass (float glass), quartz glass, borosilicate glass, and/or soda lime glass.
In the context of the invention, “etching” includes both the treatment of the surface of the pane with an acid and with a basic solution. These two steps can even occur one after another in any order. After etching or in the case of different etching solutions, the pane is washed and/or cleaned preferably with deionized water. All (multiple) areas of the pane as well as only one area of the pane can be etched.
The etched pane is then heated to a temperature of 500° C., to 800° C. Rapid cooling (quenching) of the heated, etched pane follows the heating. In this process, the surface of the pane cools faster than the core zone, such that tensions develop in the glass. These increase the stability and the strength of the glass. Together, heating and rapid cooling constitute the tempering process of the method according to the invention. The pane is cooled preferably to a temperature of 25° C. to 70° C., particularly preferably 35° C. to 50° C. within 30 s to 150 s by cold air jet.
The etching takes place preferably by applying and/or spraying a solution of an acid and/or base on the surface of the pane.
The etching takes place preferably by dipping the pane in a solution of an acid and/or base.
The pane is preferably etched with HF, H2SiF6, (SiO2)m*nH2O (m, n=0, 1, 2, 3, . . . ), HCl, H2SO4, H3PO4, HNO3, CF3COOH, CCl3COOH, HCOOH, CH3COOH, NaOH, KOH, Ca(OH)2, and/or mixtures thereof.
The pane is preferably treated in a first step with an HF or NaOH solution. The pane is then washed one or a plurality of times with deionized water. The actual etching of the pane takes place preferably with a solution of H2SiF6 and (SiO2)m*nH2O. The concentration of colloidally dissolved (SiO2)m*nH2O is preferably as much as 3 mmol above the (SiO2)m*nH2O saturation concentration. A more detailed description in this regard is found in DE 822 714 B, the content of which is part of the present application.
The etched pane is preferably heated to 550° C. to 650° C.
The heated, etched pane is cooled, preferably within 50 s to 90 s. The cooling takes place preferably with a cold air jet.
The invention further includes a reflection-reduced pane produced in accordance with the method according to the invention. The pane comprises at least one pane body and at least one reflection-reduced pane surface.
The surface of the pane has preferably a transmission (as energy transmission according to DIN-EN 410:1998) of >80%, preferably of >90%.
The surface of the pane has preferably a refractive index of 1.20 to 1.45, particularly preferably of 1.25 to 1.40.
The layer thickness of the surface of the pane is preferably 10 nm to 1000 nm, particularly preferably 50 nm to 200 nm.
The surface of the pane contains HF, H2SiF6, (SiO2)m*nH2O, HCl, H2SO4, H3PO4, HNO3, CF3COOH, CCl3COOH, HCOOH, CH3COOH, NaOH, KOH, Ca(OH)2, and/or mixtures thereof.
The body of the pane has preferably a transmission of >80%, preferably of >90%.
The body of the pane has preferably an area of >0.5 m2, preferably of >5 m2, and particularly preferably of >19 m2.
The invention further includes the use of the pane according to the invention as a reflection-reduced pane.
The pane according to the invention is used preferably as building glass, motor vehicle glazing, and/or photovoltaic glazing.
In the following, the invention is explained in detail with reference to a drawing and one embodiment as well as one comparative example. The drawing is a purely schematic depiction and is not true to scale. It is no way restricts the invention.
An exemplary embodiment of the invention is depicted in the drawing and is described in detail in the following.
The figures depict:
The reference characters signify:
(1) Pane surface,
(2) Pane body,
(3) Pane.
In the following, the invention is explained in detail with reference to an example of the method according to the invention and a comparative example.
In two series of experiments, the relative fluorine concentration of the pane surface (1) of a pane according to the invention (Example 1) and a control pane (Comparative Example 2) made of soda lime glass was compared. In the context of the invention, the expression “relative fluorine concentration” refers to the intensity of the Cs2F+ signal in the ToF-SIMS experiment. Based on the signal intensities, it is possible to make a statement concerning the relative concentration ratio of fluorine in the pane surface (1) of the pane (3) according to the invention (Example 1) and the control pane (3) (Comparative Example 2).
The pane was pre-etched with an HF solution (2 wt.-%), washed with deionized water, and etched with H2SiF6 (1.2 mol/L) for 30 min to 120 min in an immersion bath. The pane was then washed with deionized water and dried. In a second step, the pane was heated to 600° C. and cooled within 70 s in the cold air jet (tempering).
For the subsequent analysis and detection of the Cs2F+ signal, an IONTOF “TOF.SIMS 5” of the company ION-TOF (Tascon) GmbH (48149 Münster, Germany) was used. For the sputtering, a 1-keV Cs+ ion beam, a current of 100 nA was used on a sample area of 300×300 μm2. The analysis was carried out with a 25-keV Bi3+ ion beam and a current of 0.5 pA on an area of 100×100 μm2. The polarity was positive. The resulting spectrum is depicted in
The control pane (3 differs from the Example 1 according to the invention in that the control pane was tempered at approx., 600° C. before etching and was cooled within approx. 70 s in the cold air jet. The etching was then carried out under the same conditions as is in Example 1.
For the subsequent analysis and detection of the Cs2F+ signal, an IONTOF “TOF.SIMS 5” of the company ION-TOF (Tascon) GmbH (48149 Münster, Germany) was used. For the sputtering, a 1-keV Cs+ ion beam, a. current of 100 nA was used on a sample area of 300×300 μm2. The analysis was carried out with a 25-keV Bi3+ ion beam and a. current of 0.5 pA on an area of 100×100 μm2. The polarity was positive. The resulting spectrum can be seen in
A comparison of the maxima of the relative intensities of Example 1 according to the invention and of the Comparative Example 2 is found in Table 1.
Table 1 indicates a signal intensity for fluorine in Example 1 according to the invention that is higher by a factor of 10 than in the Comparative Example 2. Thus, a. higher proportion of fluorine is bound by the etching process on the pane surface (1) of a pane (3) produced in accordance with the method according to the invention (Example 1), than with a control pane (3) produced according to the prior art (Comparative Example 2) from the same basic material.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102009025788.8 | May 2009 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2010/056433 | 5/11/2010 | WO | 00 | 8/26/2011 |
