JP5975023B2 - Method for producing surface-treated glass substrate - Google Patents

Description

  The present invention relates to a method for producing a surface-treated glass substrate. In particular, a glass substrate capable of efficiently forming a layer having a refractive index lower than that of glass (hereinafter also simply referred to as “low refractive index layer”) on the glass surface by bringing a fluorine-based gas into contact with the glass substrate being conveyed. The present invention relates to a manufacturing method and a manufacturing method of chemically strengthened glass for chemically strengthening the surface-treated glass substrate.

Conventionally, in glass substrates used for applications requiring light transmission, such as glass for building materials, glass for automobiles, glass for displays, optical elements, glass substrates for solar cells, show window glasses, optical glasses, and eyeglass lenses. In order to increase the transmittance, an antireflection film may be formed on the surface of the glass substrate. For example, in order to obtain a highly permeable glass member, a fluoride film such as MgF _{2 is} formed on the surface by a method such as dry coating such as vapor deposition or sputtering, or wet coating such as coating or spin coating. An antireflection film made of a hollow SiO ₂ film has been formed.

However, since a functional film having a property different from that of the glass substrate is formed, the adhesion between the glass substrate and the functional film is poor, and there is a problem that the film is easily peeled off by an operation such as wiping. A method of forming an antireflection film by bringing a forming agent into contact with each other to form a porous structure on the glass surface (hereinafter also referred to as “etching”) is known (Patent Documents 1 to 3).
This is because, on the glass surface, the fluorine-based compound reacts with SiO ₂ which is a glass skeleton structure to generate SiF ₄ (gas), and as a result, the remaining components that have lost the skeleton become silicofluoride, It is presumed that a porous region is formed on the surface.

In Patent Document 1, as the fluorinating agent, fluorine alone (F ₂ ) or fluorine capable of forming a bond between a fluorine atom and a metal atom by cutting a bond between an oxygen atom and a metal atom in the glass skeleton. Compounds such as hydrogen fluoride (HF), silicon tetrafluoride, phosphorus pentafluoride, phosphorus trifluoride, boron trifluoride, nitrogen trifluoride, chlorine trifluoride are mentioned, among others It is described that fluorine alone is most preferable because it has high reactivity and can shorten the reaction time. Here, as the concentration of the fluorinating agent, it is described that if the concentration is too low, the reaction rate becomes slow and the treatment time becomes long, and if the concentration is too high, the reaction becomes fast and the control of the reaction becomes difficult. It is described that the fluorine atom concentration on the glass surface can be increased by increasing the temperature of the fluorinating agent and / or increasing the pressure. Specifically, in forming the porous structure, When fluorine alone is used as the fluorinating agent and the F ₂ concentration is 20 mol%, the surface treatment is performed at 20 to 80 ° C. for 1 to 8 hours, and when the F ₂ concentration is 2 mol%, 550 Surface treatment is performed at ˜600 ° C. for 15 minutes.

  Patent Document 2 discloses that by controlling the hydrogen fluoride concentration on the glass surface to 1 mol% or less, the surface of the glass is adhered at low cost without causing deterioration of surface characteristics due to excessive etching action. In order to control the above-mentioned hydrogen fluoride concentration to 1 mol% or less, it is described that hydrogen fluoride is not used as a fluorinating agent. In Patent Document 3, surface treatment is performed on a glass substrate at 10 ° C. to 60 ° C. using a gas containing hydrogen fluoride and water.

  On the other hand, in Patent Document 4, by supplying a gas containing a halogen element to the surface of a heated soda lime or glass ribbon on a molten metal bath, the alkali ions existing on the glass surface are reduced, A technique for preventing alteration of a conductive film formed on the surface is described.

International Publication No. 2008/156177 International Publication No. 2008/156176 Japanese Laid-Open Patent Publication No. 4-251437 Japanese Patent No. 4322596

As mentioned above, a technology for providing a low refractive index layer having a refractive index lower than that of glass by providing a porous structure (unevenness) on the surface by bringing a fluorinating agent into contact with the surface of the glass substrate is known. It is described that if the concentration of the agent is too low, the reactivity is poor and it takes time, while if the concentration is too high, it is difficult to control the reaction. However, it is desired to realize a technique for manufacturing a glass substrate having a low-reflectance layer with better performance and efficiency.
Further, Patent Document 4 exemplifies hydrogen fluoride as a halogen element. However, Patent Document 4 describes a technique for reducing alkali ions existing on the glass surface, and specifically, supplying chlorine-based gas. Although it is common in that a halogen-based gas is supplied onto the glass substrate, it is not a technique for obtaining a low reflectance layer, and specific reaction conditions in a fluorine-based gas are not described.

  As a result of various investigations under such circumstances, the present inventors have used a gas or liquid containing molecules having fluorine atoms in the structure while transporting the glass, and under specific temperature conditions. By treating the glass surface, the inventors have found that a glass substrate having an excellent low refractive index layer or a glass substrate with little warpage can be obtained even when chemically strengthened, and arrived at the present invention. . That is, the present invention has the following configuration.

(1) A method for producing a glass substrate in which at least one surface of the glass substrate is surface-treated, wherein the glass substrate temperature is 400 ° C. to Tg + 60 when the glass transition temperature of the glass substrate is Tg. A method for producing a surface-treated glass substrate, comprising bringing a gas or liquid containing a molecule having a fluorine atom in its structure into contact with a glass substrate being conveyed in a range of ° C. .
(2) A method for producing a glass substrate by subjecting at least one surface of the glass substrate to a surface treatment to form a layer having a refractive index lower than that of glass on the surface, wherein the surface treatment is carried out by changing the glass transition temperature of the glass substrate. When the glass substrate is in the range of 400 ° C. to Tg + 60 ° C. when the temperature of the glass substrate is Tg, a gas or liquid containing molecules having fluorine atoms in the structure is brought into contact with the glass substrate being conveyed. A method for producing a surface-treated glass substrate, characterized in that:
(3) The surface-treated glass as described in (1) or (2) above, wherein the surface treatment is carried out by contacting a gas or liquid containing hydrogen fluoride or hydrofluoric acid. A method for manufacturing a substrate.

(4) A glass in which the glass substrate includes a melting furnace that melts a glass raw material, a float bath that floats molten glass on a molten metal and forms a glass ribbon, and a slow cooling furnace that slowly cools the glass ribbon. The method for producing a glass substrate according to any one of the above (1) to (3), wherein the glass substrate is produced using a production apparatus.
(5) A gas containing a molecule having a fluorine atom in its structure by an injector disposed in the slow cooling region with respect to at least one surface of the glass ribbon that is transporting the slow cooling region in the surface treatment or The method for producing a glass substrate according to the above (4), which is carried out by blowing out a liquid.

(6) A glass substrate produced by the method described in (1) or (2) above and having a layer having a refractive index lower than that of glass on the surface.
(7) A method for producing chemically tempered glass, wherein the glass substrate produced by the method according to any one of (1) to (5) is chemically strengthened.
(8) Chemically strengthened glass produced by chemically strengthening the glass substrate according to (6) above.

According to the present invention, a gas or liquid containing a molecule having a fluorine atom in its structure is specified from 400 ° C. to a glass transition temperature (Tg) of the glass composition + 60 ° C. It has been found that a low refractive index layer having a very low refractive index and excellent performance can be obtained efficiently in a very short time by continuously contacting in the above temperature range.
According to the conventional known technique, a gas or liquid containing a molecule having a fluorine atom in its structure is considered to be too reactive, and even if used, it is processed at a low temperature. It is presumed that an appropriate treatment can be realized in a short time by continuously applying the surface treatment, while performing such a surface treatment in a temperature range of 400 ° C. to Tg + 60 ° C. It has been found that a low reflectivity layer having an excellent low refractive index and mechanical strength can be obtained.

That is, it is found that an excellent low-refractive-index layer can be formed by performing a short-time treatment at a high temperature above a certain temperature under a continuous conveyance process, and an etching process, that is, a fluorine-based material. When reacting a compound with SiO ₂ , which is a glass skeleton structure, it is not just a matter of raising the reactivity by simply raising the temperature, but the effect of reducing the reflectivity is drastically reduced at temperatures exceeding Tg + 60 ° C. Is found. This is presumed that when the temperature exceeds this temperature, the movement of each atom constituting the glass becomes somewhat free, so that the porous structure (uneven structure) once etched is relaxed, and the glass to be conveyed It has been found that the glass transition point is an excellent index in the high-speed and high-activity etching process for the above.
In addition, since the glass produced by the float process has different composition of the outermost layer between the contact surface and the non-contact surface with respect to the molten metal bath, there is a problem that if the chemical strengthening is performed as it is, the non-contact surface becomes convex and warpage is likely to occur. However, when the glass substrate obtained by performing the above surface treatment was chemically strengthened, it was found that an excellent chemically strengthened glass with less warpage can be obtained. Therefore, the surface-treated glass substrate has excellent performance as a glass substrate for chemical strengthening.

According to the present invention, a glass substrate having a low refractive index layer having a very low refractive index and good mechanical strength can be obtained efficiently in a very short time.
In addition, since the method of the present invention can continuously process the conveyed glass, it can be incorporated in the production process of a glass substrate produced by the float process, and the productivity is remarkably improved. Can be made. In particular, the low-reflectance layer can be provided more efficiently by performing the surface treatment on the glass substrate in the temperature range in the slow cooling region. Furthermore, by chemically strengthening the obtained glass substrate, an excellent chemically strengthened glass with less warpage can be obtained. Low-reflectivity layer efficiently in the same time as the conventional chemically tempered glass manufacturing process by continuously treating the glass substrate with a gas or liquid containing molecules with fluorine atoms in the structure. Chemically strengthened glass having

  Further, according to the present invention, a glass substrate obtained by a short-time treatment under a highly active condition with a gas or liquid containing a molecule having a fluorine atom in its structure exhibits a very excellent transmittance. The surface shape created on the glass substrate can control the concavo-convex shape, depth, etc. by controlling the processing temperature and gas conditions, and by using the present invention, the surface shape is more excellent. A glass substrate having a surface shape showing transmittance can be designed. Further, by chemically strengthening a glass substrate having a porous structure on the surface by bringing a fluorinating agent into contact with the surface of the glass substrate, it is possible to reduce the warp caused by making the molten metal bath non-contact surface convex. .

FIG. 1 is a diagram schematically showing a double-flow type injector that can be used in the present invention. FIG. 2 is a diagram schematically showing a single-flow injector that can be used in the present invention. FIG. 3 is an AFM image of the glass substrate obtained in Example 1 (viewing field 2 micron angle).

Hereinafter, the present invention will be described in detail.
The glass substrate used in the present invention is not necessarily flat and plate-like, and may be curved or irregular, for example, a glass substrate called a template having a surface formed with a molding roller surface pattern during glass molding. Good.
As the glass substrate, use a transparent glass plate made of colorless and transparent soda lime silicate glass, aluminosilicate glass, borate glass, lithium aluminosilicate glass, quartz glass, borosilicate glass substrate, alkali-free glass substrate, and other various glasses. Can do.
Moreover, when using for the base | substrate for solar cells, it is preferable that the thickness of a glass base | substrate is 0.2-6.0 mm. Within this range, the glass substrate is preferred because of its high strength and high transmittance. The substrate preferably has a high transmittance in the wavelength region of 350 to 800 nm, for example, a transmittance of 80% or more. Moreover, it is desirable that it is sufficiently insulating and has high chemical and physical durability.

  In the present invention, a glass substrate in which an alkali element, alkaline earth element, or aluminum is contained in the component is preferable, and specific examples include soda lime silicate glass and alumino silicate glass. In the case of a glass substrate containing an alkali element, an alkaline earth element or aluminum, the surface of the glass substrate is treated with a gas or liquid containing a molecule in which a fluorine atom is present in the structure, whereby F is formed on the outermost glass layer. This is preferable because the transmittance of the glass substrate can be increased by taking advantage of the low refractive index characteristic of fluoride. Zirconium may be contained in the components of the glass substrate.

Alkali elements, alkaline earth elements and aluminum are known to form compounds with fluorine. The compound of these elements and fluorine has a refractive index (n ₁ ) lower than that of glass, and when formed on the glass substrate surface, an intermediate refractive index between the refractive index (n ₂ ) of the glass substrate and the refractive index of air (n ₀ ). It becomes the film which has. That is, n ₀ <n ₁ <n ₂ . The glass substrate, the coating with the fluorine compound, and the air are arranged in this order to reduce the reflectivity. As a result, the transmittance of the glass substrate treated with a gas or liquid containing a molecule having fluorine atoms in its structure is untreated. Since the transmittance is higher than that of the glass substrate, it is more suitable as the glass substrate of the present invention.

  In the present invention, a “low refractive index layer” having a refractive index lower than that of glass can be formed by forming a porous structure on the surface of the glass substrate. By the method of the present invention, the average transmittance from 400 nm to 1100 nm can be increased by 1.0% or more, and further by 1.5% or more, compared with an untreated glass substrate.

  Here, “a porous structure is formed on the surface of the glass substrate” means that a large number of holes (open holes) are formed on the surface of the glass substrate, as shown in FIG. It means a state. The size of the holes formed on the surface of the glass substrate is not particularly limited, but in order to form a low refractive index layer on the surface of the glass substrate, Ra (JIS B 0601 (1994) in the surface shape observed by AFM. ) Is preferably 1 to 200 nm, more preferably 2 to 100 nm, and even more preferably 2 to 70 nm. Further, the maximum height difference is preferably 35 to 400 nm, more preferably 35 to 350 nm, and still more preferably 35 to 200 nm.

Moreover, although the surface area is increased by the pores formed on the surface of the oxide glass, as described later, a low refractive index layer is formed on the surface of the oxide glass and / or the surface of the oxide glass is made hydrophilic. In order to impart, the surface area ratio (S-ratio) of the oxide glass surface is preferably 1.1 to 3.0, more preferably 1.1 to 2.7, and 1.1 to 3.0. More preferably, it is 2.5.
Moreover, the oxide glass surface-treated by the method of the present invention has improved wettability of the surface due to the formation of a porous structure on the surface, and fluorine has been introduced into the surface of the oxide glass. Hydrophilicity is imparted to the surface of the oxide glass by an action such as the presence of a polar group on the surface of the oxide glass. And, by imparting hydrophilicity to the surface of the oxide glass, the effects of improving the antifouling property of the surface and improving the antifogging property are exhibited.

The low refractive index layer of the present invention is formed by etching a glass substrate with a gas or liquid containing molecules having fluorine atoms in the structure. The atomic concentration of fluorine on the surface of the glass substrate provided with the low refractive index layer is preferably 1% or more. In general, fluorides are known to have many low refractive index compounds. Examples of the fluoride include crystalline compounds such as NaF, KF, MgF ₂ and CaF ₂ . The NaF, _KF, amorphous compounds of similar composition as such MgF 2, CaF ₂ may be mentioned. In addition, a crystalline compound and an amorphous compound containing two or more elements and F, as typified by Na ₃ AlF ₆ , can be mentioned, but the invention is not limited thereto.

  The low refractive index layer obtained in the present invention has a glass substrate surface that the atomic ratio Na / Si calculated from the elemental composition of the surface is at least twice that of the original glass substrate Na / Si. It is preferably treated with a gas or liquid containing a molecule having a fluorine atom in its structure. Similarly, it is preferable that the atomic ratio F / Si calculated from the elemental composition of the surface is 0.05 or more in that a sufficiently low refractive layer is formed on the surface of the glass substrate.

  When surface treatment is performed by supplying a gas or liquid containing molecules having fluorine atoms in the structure to the surface of the glass substrate being transported, for example, when the glass substrate is flowing on a conveyor It may be supplied from the side not touching the conveyor. Moreover, you may supply from the side which touches a conveyor by using the mesh raw material in which some glass base | substrates, such as a mesh belt, are not covered for a conveyor belt. Alternatively, two or more conveyors may be arranged in series, and an injector may be installed between adjacent conveyors to supply the gas from the side in contact with the conveyor to treat the glass substrate surface. In addition, when the glass substrate is flowing on the roller, the gas may be supplied from the side not touching the roller, or the gas is supplied from between adjacent rollers on the side touching the roller. May be. In any case, in order to produce a chemically strengthened glass according to the present invention, a surface treatment is performed by supplying a gas or a liquid containing molecules having fluorine atoms in the structure from the non-contact surface side to the molten metal bath. May be. Further, the molten metal bath may be subjected to surface treatment by supplying a gas or a liquid containing molecules having fluorine atoms in the structure from both the contact surface and the non-contact surface. When treating from both sides, it is preferable that the number of fluorine atoms contained in the chemical treated from the non-contact surface side of the molten metal bath is greater than the number of fluorine atoms contained in the chemical treated from the contact side of the molten metal bath. When the number of fluorine atoms contained in the chemical treating the molten metal bath contact surface is equal to or less than the number of fluorine atoms contained in the chemical treating the non-contact surface, warpage during chemical strengthening is not reduced. Moreover, when processing from both sides, it is not necessary to use the same drug, and different drugs may be used.

In the present invention, the temperature of the glass substrate when the gas or liquid containing molecules having fluorine atoms in its structure is supplied to the surface of the glass substrate being transported to treat the surface is important, When the glass transition temperature of the glass substrate is Tg, the surface temperature of the glass substrate is in the range of 400 ° C. to Tg + 60 ° C.
When the surface temperature of the glass substrate is lower than 400 ° C., the reaction rate constant in the reaction between a gas or liquid containing molecules having fluorine atoms in the structure and an element such as Si forming the glass skeleton becomes small. The reaction that forms the low refractive index layer is unlikely to occur, and because it is a treatment for the glass substrate being transported, a gas or liquid containing molecules having fluorine atoms in the structure can be sufficiently supplied. In addition, since the reaction time with the glass substrate cannot be sufficiently provided, it is difficult to form the low refractive index layer. The surface temperature of the glass substrate is typically 450 ° C. or higher. When the surface temperature of the glass substrate is 450 ° C. or higher, the chemical strengthening treatment temperature typical when chemically strengthening the glass substrate produced by performing the surface treatment of the present invention is lower than the surface treatment temperature. It becomes easy to hold the low refractive index layer. On the other hand, when the surface of the glass substrate is treated at a temperature exceeding Tg + 60 ° C., the viscosity of the glass is low and atoms in the glass are easy to move, even if irregularities are generated on the surface. Will be relaxed. A more preferable temperature range is 400 ° C. to Tg + 50 ° C., further 450 ° C. to Tg + 50 ° C., more preferably 400 ° C. to Tg + 40 ° C., and further 450 ° C. to Tg + 40 ° C.

  The pressure of the glass substrate surface when supplying a gas or liquid containing molecules having fluorine atoms in the structure to the glass substrate surface is an atmosphere in the pressure range of atmospheric pressure−100 Pascal to atmospheric pressure + 100 Pascals. It is preferably carried out in an atmosphere, and more preferably in an atmosphere in the pressure range of atmospheric pressure−50 Pascal to atmospheric pressure + 50 Pascal.

  In addition, it reacts with a gas or liquid supply port containing a molecule having a fluorine atom in its structure, a gas or liquid containing a molecule having a fluorine atom in its structure, and a glass substrate. Or a gas exhaust port formed by reaction of two or more gases out of a gas or a liquid containing molecules having fluorine atoms in the structure thereof, and a gas exhaust port on the same side surface of the glass substrate. It is preferable.

  Examples of the gas or liquid containing a molecule having a fluorine atom in the structure used in the present invention include hydrogen fluoride (HF), hydrofluoric acid, fluorine alone, trifluoroacetic acid, carbon tetrafluoride, tetrafluoride. Examples thereof include silicon fluoride, phosphorus pentafluoride, phosphorus trifluoride, boron trifluoride, nitrogen trifluoride, and chlorine trifluoride, but are not limited to these gases or liquids. When a liquid is used, the liquid may be supplied to the glass substrate surface by spray coating, for example, or may be supplied to the glass substrate surface after vaporizing the liquid. Moreover, you may dilute with another liquid and gas as needed. As the gas or liquid containing a molecule having a fluorine atom in its structure, hydrogen fluoride or hydrofluoric acid is preferable because of its high reactivity with the glass substrate surface. Moreover, you may mix and use 2 or more types among these gases.

The gas or liquid containing a molecule having a fluorine atom in its structure used in the present invention may contain a liquid or a gas other than those liquids or gases, and a molecule having a fluorine atom at room temperature. It is preferably a liquid or gas that does not react with. Examples thereof include N ₂ , air, H ₂ , O ₂ , Ne, Xe, CO ₂ , Ar, He, and Kr, but are not limited to these. Moreover, 2 or more types of these gases can also be mixed and used. As a gas carrier gas containing molecules having fluorine atoms in its structure, it is preferable to use an inert gas such as N ₂ or argon.

Further, the gas containing a molecule having a fluorine atom in its structure may further contain SO ₂ . SO ₂ is used when a glass substrate is continuously produced by a float process or the like, and has a function of preventing wrinkles from being generated on the glass due to the conveyance roller coming into contact with the glass substrate in the slow cooling region. Moreover, the gas decomposed | disassembled at high temperature may be included.

  Further, the gas or liquid containing a molecule having a fluorine atom in its structure may contain water vapor or water. Water vapor can be extracted by bubbling an inert gas such as nitrogen, helium, argon, carbon dioxide in heated water. When a large amount of water vapor is required, it is also possible to take a method in which water is sent directly to the vaporizer and vaporized directly. When HF is used as a gas or liquid containing a molecule having a fluorine atom in its structure, the molar ratio of HF to water ([water] / [HF]) is preferably 10 or less. When HF and water coexist, it is considered that hydrogen bonds are formed between HF molecules and water molecules, and HF acting on the glass substrate is reduced. When [water] / [HF] exceeds 10, the amount of HF acting on the glass is very small. As a result, the increase in average transmittance from 400 nm to 1100 nm compared with the untreated glass substrate is 1.0. %. [Water] / [HF] is more preferably 5 or less from the viewpoint that HF acting on the glass substrate does not decrease.

Here, the case where HF is used as a gas or liquid containing a molecule having a fluorine atom in its structure will be described as a representative. When processing the glass substrate with HF, the higher the HF flow rate, the higher the average transmittance of 400 to 1100 nm, which is preferable. When the total gas flow rate is the same, the higher the HF concentration, the higher the average transmittance of 400 to 1100 nm. Will increase. When the flow rate of HF gas is the same, the average transmittance of 400 to 1100 nm increases as the total gas flow rate decreases. In this case, the fact that the total gas flow rate is small means that the gas flow rate passing through the blowout port when the gas is blown onto the surface of the glass substrate is small. That is, it can be paraphrased that the average transmittance of 400 to 1100 nm increases as the gas flow rate decreases.
When both the total gas flow rate and the HF gas flow rate are the same, the longer the time for processing the glass substrate, the higher the average transmittance of 400 to 1100 nm. For example, when the glass substrate surface is treated with a gas or a liquid containing molecules having fluorine atoms in the structure after the glass substrate is heated, the average transmittance of 400 to 1100 nm is reduced as the conveyance speed of the glass substrate is lower. Will increase. Even in facilities where the total gas flow rate and HF flow rate cannot be controlled well, the degree of increase in the average transmittance of 400 to 1100 nm can be controlled by controlling the conveyance speed of the glass substrate.

  The glass substrate of the present invention can be produced by conveying the glass substrate by ordinary roller conveyance, as represented by the float process. In the float process, a glass manufacturing apparatus having a melting furnace for melting glass raw materials, a float bath for floating glass on a molten metal (such as tin) to form a glass ribbon, and a slow cooling furnace for gradually cooling the glass ribbon Is used to produce a glass substrate. When glass is formed on a molten metal (tin) bath, the glass substrate transported on the molten metal bath contains molecules with fluorine atoms in the structure from the side not touching the metal surface. The surface of the glass substrate may be treated by supplying a gas or liquid to be supplied. In the slow cooling region following the molten metal (tin) bath, the glass substrate is conveyed by roller conveyance. Here, the slow cooling region includes not only the inside of the slow cooling furnace but also the portion from the time when the molten metal (tin) bath is carried out in the float bath to the time when it is carried into the slow cooling furnace. In the slow cooling region, the gas may be supplied from the side not touching the molten metal (tin). Especially in the range from the float bath to the slow cooling region, the glass is cooled from the temperature at the time of melting the glass and takes a temperature of 400 ° C. to Tg + 60 ° C. More cost savings.

  When the “gas or liquid containing molecules having fluorine atoms in its structure” supplied from the injector is a gas, the distance between the gas outlet of the injector and the glass substrate is preferably 50 mm or less. Since gas diffuses in air | atmosphere as it is 50 mm or more, the gas which reaches | attains a glass base | substrate will decrease with respect to desired gas amount. On the other hand, when the glass substrate produced by the float process is on-line, for example, when the distance from the glass substrate is too short, the glass substrate and the injector may come into contact with each other due to fluctuations in the glass ribbon. In addition, when the “gas or liquid containing a molecule having a fluorine atom in its structure” supplied from the injector is a liquid, there is no particular limitation on the distance between the liquid discharge port of the injector and the glass substrate. Any arrangement may be used as long as the substrate can be processed uniformly.

  The injector may be used in any mode such as double-flow or single-flow, and two or more injectors may be arranged in series in the flow direction of the glass substrate to treat the surface of the glass substrate. As shown in FIG. 1, the double-flow injector is an injector in which the gas flow from discharge to exhaust is equally divided in the forward direction and the reverse direction with respect to the moving direction of the glass substrate. The single-flow injector is an injector in which the gas flow from discharge to exhaust is fixed in either the forward direction or the reverse direction with respect to the moving direction of the glass substrate, as shown in FIG. When a single-flow injector is used, it is preferable that the gas flow on the glass substrate and the moving direction of the glass substrate are the same in terms of airflow stability.

  In the present invention, the gas may be supplied from both the side not touching the roller and the side touching the roller to perform the surface treatment of the present invention. For example, when supplying gas from both sides in the slow cooling region, place the injector against the glass that is being continuously conveyed so that it faces the glass substrate, and the roller that does not touch the roller. You may supply the said gas from the both sides of the side which touches. Moreover, you may arrange | position the injector arrange | positioned at the side which is contacting the roller, and the injector arrange | positioned at the side which is not touching a roller in the position which differs in the flow direction of a glass base | substrate. In arranging at different positions, any of them may be arranged upstream or downstream with respect to the flow direction of the glass substrate.

  The same gas may be supplied from both sides to give the same function to both sides of the glass substrate. For example, when a glass substrate surface is treated by supplying a gas or a liquid containing molecules having fluorine atoms in the structure on both sides, and one side is treated, it is from 400 nm as compared with an untreated glass substrate. While the average transmittance up to 1100 nm can be increased by 1.0% or more, the average transmittance from 400 nm to 1100 nm can be increased by 2.0% or more compared to an untreated glass substrate. . For example, in the slow cooling region of the float process, a gas or a liquid containing molecules having fluorine atoms in the structure is supplied to each surface of both surfaces of the glass substrate, without changing the glass composition and once. With this process, a glass substrate having a high transmittance can be produced. Since a glass substrate having a high transmittance can be produced in a single process in accordance with a normal method for producing a glass substrate, it is very useful as a low-cost process.

  It is also possible to give different functions to both surfaces of the glass substrate. It is widely known that a glass substrate with a transparent conductive film is manufactured on-line by combining a glass manufacturing technique using a float process and a CVD technique. In this case, it is known that the transparent conductive film and the underlying film are formed on the glass substrate by supplying gas from the surface not touching the tin or the surface not touching the roller. Yes. For example, in the production of a glass substrate with a transparent conductive film by this on-line CVD, an injector is arranged on the surface in contact with the roller, and a gas or liquid containing molecules having fluorine atoms in the structure from the injector to the glass substrate May be supplied to treat the surface of the glass substrate. As a result, the surface of the glass substrate opposite to the surface on which the transparent conductive film is provided is treated, and the transparent conductive film is provided on the glass substrate having a high transmittance in a series of processes of the float process. It is possible to produce a highly transparent glass substrate.

In the present invention, the chemical strengthening treatment can be performed by a conventionally known method. Prior to the chemical strengthening treatment, it is preferable to perform shape processing according to the application, for example, mechanical processing such as cutting, end surface processing and drilling processing.
By contacting the glass substrate by chemical strengthening treatment, such as by immersion in a metal salt (for example, potassium nitrate) melt containing a metal ion (typically K ion) having a large ionic radius, Metal ions of ionic radius (typically Na ions or Li ions) are replaced with metal ions of large ionic radius.

  The treatment conditions for the chemical strengthening treatment are not particularly limited, and the optimum conditions may be selected in consideration of the characteristics of the glass, the molten salt, and the like. It can be performed by soaking for a time. As ion exchange conditions, optimum conditions may be selected in consideration of the viscosity characteristics of glass, application, plate thickness, tensile stress inside the glass, and the like. Examples of the molten salt for performing the ion exchange treatment include alkali nitrates such as sodium nitrate, potassium nitrate, sodium sulfate, potassium sulfate, sodium chloride and potassium chloride, alkali sulfates and alkali hydrochlorides. These molten salts may be used alone or in combination of two or more. In order to adjust the degree of chemical strengthening, another element may be added to the molten salt. Other elements that can be added include, but are not limited to, magnesium, calcium, strontium, aluminum and the like. These additives may be used alone or in combination of two or more.

  By chemically strengthening the chemically strengthened glass substrate of the present invention, a chemically strengthened glass product having a functional film on the surface of the chemically strengthened glass substrate can be obtained. Examples of such chemically tempered glass products include cover glasses for display devices such as digital cameras, mobile phones, and PDAs, and glass substrates for displays.

  EXAMPLES The present invention will be described in further detail below using examples, but the present invention is not limited to these examples.

[Example A1]
A gas containing hydrogen fluoride was brought into contact with the surface of the glass substrate of the base plate A shown in Table 1 using the double-flow injector 10 used in the atmospheric pressure CVD method as shown in the schematic diagram of FIG. The surface in contact with the gas containing hydrogen fluoride was a non-contact surface of a molten metal bath of a glass substrate manufactured by a float process.
That is, from a central slit 1 shown in FIG. 1, a gas in which HF0.56 SLM (liters of gas in a standard state and liter per minute) and nitrogen (N ₂ ) 9 SLM are mixed is heated to 150 ° C. and flowed at a flow rate of 64 cm / s. the 45.5SLM the _{N 2} from the slit 2 was blown toward the glass substrate. The gas flows on the substrate 20 through the flow path 4, and the exhaust slit 5 blows and exhausts twice the gas flow rate. A hot-wire anemometer (manufactured by Kanomax Co., Ltd., Kurimo Master 6543) was used for measurement of gas temperature and flow velocity. Asa glass glass soda lime glass (thickness 1.8 mm) was used (glass transition point 560 ° C.). The glass substrate is heated to 600 ° C. and the speed is 2 m / min. It was conveyed by. The temperature of the glass substrate was measured by installing a radiation thermometer immediately before blowing the gas.

[Examples A2, A3 and A4]
In Example A1, the glass substrate surface treatment was carried out in the same manner as in Example A1, except that the glass substrate temperature was 560 ° C. (Example A2), 400 ° C. (Example A3), or 620 ° C. (Example A4). went.

[Example A5]
Surface treatment of the glass substrate was performed in the same manner as in Example 1A, except that the amount of HF in the central slit 1 was 1.12 SLM.

[Comparative Examples A1 and A2]
In Example A1, the glass substrate was subjected to a surface treatment in the same manner as in Example A1, except that the glass substrate temperature was 350 ° C. (Comparative Example A1) or 650 ° C. (Comparative Example A2).

[Examples B1 to B4]
In Example A1, instead of the base plate A, a base plate B having a glass transition temperature of 620 ° C. shown in Table 1 was used as the glass substrate. Further, the glass substrate temperature and the amount of HF in the central slit 1 were respectively shown in Table 2. The glass substrate was subjected to a surface treatment in the same manner as in Example A1 (Examples B1 to B4) except that the glass substrate was treated as described above.

[Examples C1 and C2]
In Example A1, it was carried out except that the base plate C having a glass transition temperature of 560 ° C. shown in Table 1 was used instead of the base plate A as the glass substrate, and the glass substrate temperature was changed to the temperature shown in Table 2, respectively. The glass substrate was surface treated in the same manner as in Example A1.

  The glass substrate obtained as described above was subjected to ultrasonic cleaning with pure water for 5 minutes, and then measured for transmittance, physical properties measured by AFM, Δ warpage, weather resistance and abrasion resistance as follows. .

<Transmissivity>
Apparatus: Spectrophotometer (manufactured by Shimadzu Corporation, model number UV-3100PC)
Light was incident from the treated surface and measured as an integrating sphere transmittance. The increase in transmittance with respect to the untreated glass was obtained as the antireflection performance of the obtained glass substrate, and the average value in each wavelength range of 400 to 1100 nm, 400 to 700 nm, and 600 to 900 nm was obtained.

<Ra, PV, S-ratio>
Surface roughness (Ra) when observed in DFM mode using a scanning probe microscope (SII Nanotechnology, model number SPI3800N) with an observation area of 2 μm square and a number of acquired data of 1024 × 1024 , Maximum height difference (P-V), S-ratio (value obtained by dividing the area including irregularities by the observation area).

<Weather resistance>
The surface of the treated surface was sprayed with 5 wt% saline for 2 hours, and then left in a furnace at 60 ° C. and 95% RH for 7 days. This was repeated as 4 cycles, and then washed with pure water, and the transmittance was measured. Compared with the transmittance before the test, the decrease in average transmittance in the wavelength range of 400 to 700 nm was defined as weather resistance.

<Abrasion resistance>
A felt (10.3 mm × 15 mm × 49 mm) was placed so that the 10.3 mm × 49 mm surface was in contact with the glass substrate, and a load of 1 kg was applied and reciprocated on the substrate at a speed of 10 cm / s. The transmittance after 100 reciprocations was measured and compared with the transmittance before abrasion, the decrease in average transmittance in the wavelength range of 400 to 700 nm was defined as wear resistance. The larger the value, the stronger the wear resistance, and the smaller the value, the smaller the wear resistance.

<Δ Warpage>
Each glass substrate obtained in Example B1 to Example B4, Comparative Example B1, Comparative Example B2, Example C1, and Example C2 was chemically strengthened by potassium nitrate molten salt at 435 ° C. for 4 hours. A glass was obtained, and the value obtained by subtracting the amount of warpage before chemical strengthening from the amount of warpage after chemical strengthening (measuring instrument: three-dimensional shape measuring instrument (NH-3MA) manufactured by Mitaka Kogyo Co., Ltd.) in the 50 mm square sample was Δ Warped. When the Δ warp is a positive value, it indicates that the warp changes so that the molten metal bath non-contact surface is convex, and when the Δ warp is negative, the molten metal bath non-contact surface is concave. It shows that the warpage changes.

Table 2 shows the results of transmittance, physical property values measured by AFM, and Δ warpage.
Moreover, when the weather resistance of the glass substrate obtained in Example A1 was measured, it was -1.8%, and sufficient weather resistance was obtained.
Moreover, when the abrasion resistance of each glass substrate obtained in Example 1, Example 2 and Example 5 was measured as follows, -0.3%, -0.7% and -1. It was 4%, and sufficient wear resistance was obtained.

  As shown in Table 2, in Examples A1 to A5 in which HF gas was brought into contact with the glass surface in the temperature range of the present invention, the glass substrate having a low reflectance superior to Comparative Examples A1 and A2 was 2 m / It can be seen that it can be obtained efficiently at a high speed of minutes. It can also be seen that the weather resistance and abrasion resistance are sufficient.

  Moreover, it turns out that the glass base | substrate which has the low reflectance similarly excellent also in Example B1-B4 and Example C1 and Example C2 which used another glass base | substrate is obtained. Furthermore, it can be seen that when these glass substrates are chemically strengthened, Δ warpage before and after chemical strengthening is remarkably reduced as compared with the case where no surface treatment is performed (Comparative Example B1 and Comparative Example B2).

  In addition, using the AFM image obtained in Example A1 (scanning probe microscope (manufactured by SII Nano Technology, model number SPI3800N), the observation area is 2 μm □, the number of acquired data is 1024 × 1024, and in DFM mode. What was observed) is shown in FIG.

  This application is based on a Japanese patent application filed on April 15, 2011 (Japanese Patent Application No. 2011-091437), the contents of which are incorporated herein by reference.

  According to the method of the present invention, it is possible to efficiently and continuously produce a glass substrate having an excellent low reflectance layer. Further, the performance of the obtained low reflectance layer is sufficiently excellent. Therefore, the surface-treated glass substrate obtained according to the present invention is used for light transmission of glass for building materials, glass for automobiles, glass for displays, optical elements, glass substrates for solar cells, show window glass, optical glass, eyeglass lenses, etc. It is widely used for applications that require high performance, and can be used particularly in the fields of TCO substrates for thin film silicon solar cells, cover glasses for crystalline silicon solar cells, displays and the like. The TCO substrate for thin-film silicon solar cells has been tandemly used in order to efficiently use sunlight. The light in the wavelength range of 400 to 700 nm has high quantum efficiency particularly in the amorphous silicon layer, and the light in the wavelength range of 600 to 900 nm has high quantum efficiency in particular in the microcrystalline silicon layer. Therefore, the glass substrate of the present invention is used. Thus, efficient solar power generation can be performed. In addition, since chemically tempered glass having a low reflection layer can be produced, a solar cell cover glass having a thickness of 2 mm or less and high transmittance can be produced, which can contribute to power generation efficiency and weight reduction. Further, since the warpage due to chemical strengthening can be reduced, it can be used for a large display having a low reflection layer and a display integrated product.

1 Central slit (HF and N ₂ )
2 Outer slit (N ₂ )
4 Flow path 5 Exhaust slit 10 Processing device 20 Glass substrate 21 Moving direction of glass substrate

Claims (3)

A method for producing a glass substrate, comprising: surface-treating at least one surface of a glass substrate ; and forming a layer having a lower refractive index than glass on the surface ,
When the glass transition temperature of the glass substrate is Tg in the surface treatment, the glass substrate temperature is in the range of 400 ° C to Tg + 60 ° C. There line by contacting the gas or liquid containing molecules,
A glass manufacturing apparatus, wherein the glass substrate includes a melting furnace for melting a glass raw material, a float bath for floating a molten glass on a molten metal to form a glass ribbon, and a slow cooling furnace for gradually cooling the glass ribbon. Is manufactured using,
In the surface treatment, a gas or a liquid containing molecules having fluorine atoms in the structure is blown out to at least one surface of the glass ribbon being conveyed through the slow cooling region by an injector disposed in the slow cooling region. It is characterized by
A method for producing a surface-treated glass substrate. The surface treatment, and carrying out by contacting the gas or liquid containing hydrogen fluoride or hydrofluoric acid, according to claim 1 Symbol mounting surface treated process for producing a glass substrate. Claim 1 or 2, chemically strengthened glass substrates produced by the method according to method of manufacturing a chemically strengthened glass.

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