TWI379815B - - Google Patents

Description

IX. Description of the Invention: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for producing an alkali-free glass substrate. [Prior Art] Most of the glass substrates typified by the glass substrate for display are manufactured by a float method or a simmer method. The floating method differs from the melting method in that it is known for its ability to efficiently manufacture large-area glass substrates. The floating method generally includes a forming step of forming molten glass in molten tin in molten silox into a glass substrate, and a cooling step of causing the glass substrate formed by the forming step to be cooled. However, the glass substrate formed by the forming step is transported by the drum after being taken out of the molten tin bath. Therefore, there is a flaw in the back surface of the glass substrate (touching the surface of the drum) during the transfer process, resulting in the quality of the glass substrate. The problem of decline. Therefore, in order to prevent scratches on the back surface of the glass substrate generated during the transfer, a method is known in which sulfur dioxide (s〇2 gas) is sprayed onto the back surface of the glass substrate to form an alkali metal (for example, sodium) in the glass. In the reaction, the sodium sulfate is formed on the back surface of the glass substrate to act as a protective film, thereby preventing the occurrence of scratches (for example, refer to Patent Document 1 and Non-Patent Document 1). [Patent Document 1] International Publication No. 2002/051767 (Non-Patent Document 1) U. Senturk etc, J. Non-Cryst. Solids, Vol. 222, p 16〇 (1997) [Summary of the Invention] 122464.doc 15 [Problems to be Solved by the Invention] However, in order to achieve the high resistance to high-quality displays required in recent years, it is necessary to increase the thickness of the protective film. For this reason, a large amount of sulfur dioxide must be used, so that environmental load and working environment exist. The problem of deterioration. Further, since sulfur dioxide is a highly corrosive gas, there is a problem that corrosion of the surrounding furnace material is shortened. In particular, in the case of producing a glass substrate comprising a glass which does not substantially contain an alkali metal (hereinafter also referred to as "alkali-free glass"), the method of spraying sulfur dioxide does not produce sodium sulphate in the glass substrate. Further, a salt such as calcium sulfate or barium sulfate which is a reaction product with an alkaline earth metal is formed. These salts obtained from the soil-based metal function as a film for preventing scratches on the glass substrate, but the production efficiency is remarkably lower than that of sodium sulfate, and thus the effect may not be sufficient. Further, even if yttrium is formed, it is a water-soluble salt, and thus it is extremely difficult to remove it in the subsequent washing step. Although such a salt can be removed by polishing, in order to obtain a glass substrate having a high smoothness, it is necessary to grind a considerable thickness, so that there is a problem in that the manufacturing time and the manufacturing cost increase. In addition, high-quality surfaces such as bismuth-based glass-based flat panel displays, if there is a risk of damage on the glass board, it will be broken (4), so even if it is used as a window glass or automotive glass, even smaller flaws It will also become a problem. Therefore, an object of the present invention is to provide a method for producing an alkali-free glass substrate and a non-inspective glass substrate obtained by the method of manufacturing the same. The method for manufacturing a glass substrate is to include a liquid crystal display. The glass substrate of the alkali-free glass (hereinafter also referred to as "the glass substrate No. J") can effectively form a protective film which can be easily removed in the washing step, thereby achieving a reduction in the amount of sulfur dioxide used and suppressing the glass. [Technical means for solving the problem] The present inventors have conducted intensive studies to achieve the above object, and as a result, found that in the manufacturing process using the floating method, an inorganic substance containing an alkali metal is applied to a glass substrate. The surface on the side in contact with the molten tin is sprayed, and the alkali metal is supplied to the surface, and then the S〇2 gas is sprayed onto the surface, whereby the protective film which can be easily removed in the washing step can be efficiently formed to realize the use of sulfur dioxide. The present invention is completed by reducing 'and suppressing the generation of scratches on the back surface of the glass substrate. That is, the present invention provides the following (1) (14) (1) A method for producing an alkali-free glass substrate, which is a method for producing an alkali-free glass substrate by a floating method; comprising: a molding step of forming molten glass on a molten tin into a glass substrate; a cooling step of causing the glass substrate formed by the forming step to be cold-cooled, and a first supplying step of: spraying an inorganic substance containing a metal to the surface of the glass substrate on the side in contact with the molten tin; In the second supply step, after the first supply step, the S〇2 gas is sprayed onto the surface of the glass substrate on the side in contact with the molten tin. (2) The method for producing the alkali-free glass substrate according to (1) above The above-mentioned step (i) is to be carried out between the above-mentioned forming step and the above-mentioned cold-cold step. (3) The method for producing an alkali-free glass substrate according to the above (1), wherein the ith supply step is The glass transition point of the glass substrate is ±1〇〇. (3) The method of manufacturing the alkali-free glass substrate according to the above (1), wherein the ith supply step is (5) The method for producing an alkali-free glass substrate according to any one of the above (1) to (4), wherein the second supply step is performed in the forming step and the quenching step (6) The method for producing an alkali-free glass substrate according to any one of the above (1) to (4) wherein the second supply step is based on the glass transition point soil 100 of the glass substrate. (7) The method for producing a glass-free substrate according to any one of the above (1) to (4) wherein the second supply step is carried out at 600 to 800 ° C. (8) - A method for producing an alkali-free glass substrate, which is a method for producing an alkali-free glass substrate by a floating method; comprising: a molding step of molding molten glass on a molten tin into a glass substrate; and having a first supply Steps, at 600~800. (: the inorganic material containing the alkali metal is sprayed onto the surface of the glass substrate on the side in contact with the molten tin and the second supply step, and after the first supply step, the glass is applied to the glass at 600 800 C. The surface of the substrate on the side in contact with the molten tin is sprayed with a gas of 802. (9) The method for producing an alkali-free glass substrate according to any one of the above (1) to (8), which is further disclosed in the method of I22464.doc 1379815 (10) The method for producing a non-inspective glass substrate according to any one of the above (1) to (9), wherein the inorganic material having an alkali metal of the above 3 contains sodium and boron (11) The method for producing a glass-free substrate according to the above (1G), wherein the inorganic substance containing an alkali metal is sodium tetraborate. (12) A non-inspective glass substrate, which is the above (10) Manufacturer of the manufacturing method. (13) An alkali-free glass substrate produced by the method of (10) or (11) above, wherein the glass substrate is expressed by mass percentage based on oxides:

Si02: 30~85%,

Al2〇3 : 〇~35%, B2〇3: 〇~35%,

MgO : 〇~3 5%, • CaO : 〇~35%,

SrO : 0-3 5% >

BaO : 〇 〜 3 5%, • alkali metal component: 0.5% or less, • The average surface of the glass substrate on the side in contact with the molten tin has an average rot' concentration of 4 to 10 atom%, and boron is applied to the glass substrate. The internal diffusion depth is above 5 nm. (14) An alkali-free glass substrate, expressed as an oxide based on mass percentage, comprising: 122464.doc • 10· 1379815

Si〇2 : 30-85% > a12〇3 : 0~35%, B2〇3 : 〇~35%,

Mg〇 : 〇~35〇/0,

Ca〇 : 〇~35%,

Sr〇 : 〇~35〇/0,

BaO: 〇~35%, φ metal component: 0.5% or less, at least one of the surfaces has an average butterfly concentration of 4 to 10 atom%, and the diffusion depth from the surface to the inside is 5 nm or more. [Effect of the Invention] As described below, according to the present invention, a method for producing an alkali-free glass substrate and an alkali-free glass substrate obtained by the method can be provided, and the method for producing the glass-free substrate can be efficiently produced. The protective film is easily removed in the washing step, thereby achieving a reduction in the amount of sulfur dioxide used, and suppressing the occurrence of scratches on the back surface of the glass substrate. [Embodiment] Hereinafter, the present invention will be described in detail. The method for producing an alkali-free glass substrate according to a first aspect of the present invention (hereinafter also referred to as "the method for producing the present invention") is a method for producing an alkali-free glass substrate by using a floating method to produce an alkali-free glass substrate. a method comprising: forming a step of forming a molten glass on a molten tin into a glass substrate; and a step of cooling to cool the glass substrate formed by the forming step; and 122464.doc • 11 - having: 1 supply step, 6 μ.+, Α + contact with the glass substrate and the above-mentioned molten tin benefit machine 1 (hereinafter referred to as "bottom surface") sprayed with the test metal below 'also known as 'including a metal-inorganic substance ""; and a second supply step "after the step of supplying the above-mentioned first step, to the surface of the glass substrate on the side opposite to the surface of the molten tin, that is, the inorganic substance is sprayed The bottom surface is sprayed with so2 gas. Further, the manufacturing method of the present invention preferably further comprises a washing step of removing the protective film. Next, the molding step, the cold cooling step, the first supply step, and the second supply step ' of the production method of the present invention will be described in detail, and a washing step provided as needed. [Molding step] The above-described forming step is a step of forming molten glass on a molten tin in a molten tin bath into a glass substrate. The conventionally known step in the floating method is shown in Fig. 1. Fig. 1 shows a glass using a floating method. A conceptual diagram of an example of a manufacturing line. As shown in Fig. 1, in the floating method, first, the molten glass 4 is continuously flowed from the melting kiln 3 on the 'valley surface' of the molten tin/valley 2 filled with the molten tin 1 to form a glass ribon e. Next, the glass ribbon is advanced while floating along the bath surface of the molten tin bath 2, whereby the temperature is lowered and the glass ribbon is formed into a plate shape. Thereafter, the glass substrate which is formed into a plate shape is guided by the guide rolls 5 to be conveyed to the quenching furnace 6 in a state of being continuous in the longitudinal direction. Here, the above forming step is a step of passing the molten glass 4 through a glass ribbon until it is formed into a plate shape. 122464.doc -12· 1379815 In the present invention, with the general, the main 4 $ 曰 曰 PI .. ^ hang / / method, as a molten tin bath 2, the use of covered with special refractory A tin bath furnace and a ceiling on the inside of the gold layer box are used to prevent the oxidation of the tin. As the ambient gas in the molten tin bath, a mixed gas including hydrogen and nitrogen (including hydrogen gas) can be used.

Further, the temperature condition in the (iv) tin bath of the above-mentioned forming step is the same as that of the usual floating method, and is 6 () () 4 (four). c, that is, the temperature of the molten glass flowing from the flowing person to the dazzling tin bath is set to 9 〇〇 to 1 〇 5 〇 (> c on the upstream side, and is provided in the manufacturing method of the present invention on the downstream side, The glass substrate of the alkali-free glass is formed on the molten tin by the above-described forming step. Here, the alkali-free glass means a glass which does not substantially contain an alkali metal as described above. Specifically, the alkali-free glass is in the present invention. In terms of oxides and expressed in mass percent, containing:

The amount is 2~10 volume 〇/〇) is 600~8〇〇°C. Further, the temperature is usually maintained by the heat of the molten glass, and a heater or a cooler may be used for adjusting the temperature.

Si02 : 30~85%, Al2〇3 : 0-3 5% > B2〇3 : 〇~3 5%,

MgO : 0-3 5% > CaO : 0-3 5% > SrΟ · 〇~35 °/〇 » BaO : 〇~35%, alkali metal component: 0.5% or less. In addition, the "alkali metal component" means an alkali metal component which is inevitably contained regardless of whether or not the following step 122464.doc is supplied. [Cold cooling step] The above-described cold cooling step is a step of quenching the glass substrate formed by the above-described forming step. Here, in the picture! In the above-described step of cooling, the glass substrate from the (four) plate-like shape is guided by the guide roller 5 to a step of being conveyed to the quenching furnace 6 in a state of being continuous in the longitudinal direction to be cooled. The towel of the present invention can be used as a quenching furnace to make the crucible the same as the quenching furnace used in the usual floating method. In order to control the temperature, a towel or the like can be provided. Further, the cold cooling condition of the above-mentioned cold cooling furnace is the same as that of the usual floating method, and can be set at 55 〇 to 75 Torr at the inlet of the cold furnace. For one time, the temperature drop rate can be 90 ° soil 10 ° C / m. [First Supply Step] The first supply step is a step of supplying an alkali metal to the bottom surface by spraying a metal-containing inorganic substance onto the bottom surface of the glass substrate. Here, the alkali metal-containing inorganic substance means an inorganic substance containing an alkali metal as described above, and for example, an inorganic substance containing (Li), sodium (Na), potassium (κ), cesium (Cs) or the like belongs to this. By using the alkali metal-containing inorganic substance described above, the alkali metal is supplied to the bottom surface of the glass substrate, and then the S〇2 gas is sprayed thereon, whereby a protective film containing a sulfate salt can be efficiently produced. Further, the protective film can be easily removed in the washing step. In addition, since the same protective effect can be obtained even if the amount of the S02 gas is reduced, the use amount of sulfur dioxide can be reduced, and the occurrence of scratches on the back surface of the glass substrate can be suppressed by 122464.doc -14 - 1379815. The reason for this is considered to be that the s〇2 gas sprayed by the second supply step described below preferentially reacts with the alkali metal supplied to the bottom surface, and the s〇2 gas and the alkali-free glass also have the poorly water-soluble alkaline earth. The reaction of a metalloid (Ca, etc.) is suppressed. Further, by spraying an alkali metal source containing an alkali metal-containing inorganic substance from the outside, it is possible to use a reactive organism (calcium sulfate, barium sulfate, etc.) for obtaining an S〇2 gas and an alkaline earth metal as a protective film. 〇2 The amount of S〇2 gas with less gas is used to obtain the same protective effect. Specific examples of the inorganic substance containing Na include NaOH, Na 2 S, NaCl, NaF, NaBr, and soda ash.

NaNH2, sodium f-ether, NaBH4, NaCN, NaN03, Na2B407-l〇H2〇 (sodium tetraborate decahydrate), Ν4Β4〇7, etc., may be used singly or in combination of two or more. As the inorganic substance containing K, specifically, for example, KOH, KC1, KF, KBr, KI, KCN, K2C03, potassium gluconate, KHF2, KNO3, K2B4〇7_4H2〇 (potassium tetraborate tetrahydrate) , 1^4〇7, KBF4, etc. 'These can be used alone or in combination of two or more. Specific examples of the inorganic substance containing Cs include:

Cs0H, CSC1, CSF, CsBr, CsI, acetoin, HC 2Cs, CsN03, etc., these may be used alone or in combination of two or more. The alkali metal-containing inorganic substance contains an inorganic substance of Na, and the rate of the formation of the protective film (sulfur_) formed by the second supply (four) towel described below can be further increased, thereby making it easier to remove the water. Preferably, the inorganic substance containing an alkali metal inorganic substance containing Na and boron is more preferable because the alkali-free glass substrate obtained by the production method of the present invention is further resistant after the following washing step. Abrasion. Specifically, Lu's preferably Na2B4〇7-10H2〇 'Na2B4〇7, more preferably Na2B4〇7-l〇H2〇 〇

By spraying an inorganic substance containing Na and boron, not only Na but also boron is supplied, and as a result, boron diffuses from the bottom surface to the inside of the glass substrate, and the strength of the glass substrate itself is improved. Therefore, in addition to the alkali-free glass substrate, for example, a glass substrate for a DNA wafer, a microchip, a bio-wafer, a glass substrate, or the like can be used to satisfy a high degree of scratch resistance by utilizing the diffusion of boron. In the first supply step, the alkali metal-containing inorganic substance is sprayed onto the bottom surface of the glass substrate, and the metal is supplied to the bottom surface. The spraying time (timing) and the spraying method can be appropriately exemplified as follows. Show off. 〜 The time for spraying the alkali metal-containing inorganic substance is not particularly limited as long as it is earlier than the second supply step hereinafter. Specifically, t may be simultaneously with the above-mentioned forming step, or may be followed by the following cold cooling step. However, it is preferable that the above-mentioned forming step and the above: "cold step" can further suppress the occurrence of scratches on the back surface of the glass substrate. The term "and the forming step" means that in the above-mentioned forming step, the following is the step of forming the substrate, and then the step is included in the forming step, and 'for example, 'is set in the furnace (4) to melt the bath (10). The situation of the float 122464.doc 1J79815 and the outlet part of the furnace (shield rare 'unshadowed place) can be sprayed in the unshielded area. In addition, the so-called "simultaneous with the cold step" can also be sprayed near the person σ of the cold furnace or the upstream side of the cold furnace. Further, the term "between the above-described forming step and the above-mentioned cold-cold step" means that the glass substrate may be sprayed while the glass substrate is being conveyed between the forming furnace and the quenching furnace. On the other hand, a method of spraying the above-mentioned alkali metal-containing inorganic substance may, for example, be a method of heating the above-mentioned alkali metal-containing inorganic substance and vaporizing it, and spraying the vaporized substance onto the bottom surface of the glass substrate using a nozzle; And a method of heating and vaporizing an alkali metal-containing inorganic substance by heating by a heater, heating by an infrared lamp, laser heating, or the like. Further, it is preferred that the vaporization material is sprayed at a temperature within a range of ±100 〇c of the glass transition point of the glass substrate. Particularly preferred is the glass transfer point _30 on the glass substrate. 〇 ~ Glass transition point +100 °c range. This is because if the film is sprayed in this temperature range, the glass softens at the glass transition point, so that a film is formed in the region, whereby the occurrence of scratches can be more effectively prevented. Specifically, it is preferably carried out at 600 to 800 ° C in terms of effectively vaporizing the vaporized material and spraying the surface of the glass substrate without drastically lowering the temperature of the substrate. Further, the amount of the vaporized substance to be sprayed is preferably 22 to 1 〇 L/m2, more preferably 0.2 to 3 L/m2, and particularly preferably 〇_2 to 1 L/m2. If the amount of the spray is within the range, the amount of the S〇2 gas to be sprayed can be suppressed, and the supply amount of the metal to be supplied to the bottom surface of the glass substrate can be sufficiently increased, thereby further increasing with 122464.doc 17 1379815 The production efficiency of the protective film formed by the reaction of the s〇2 gas sprayed in the second supply step. In the case of using the tetra-sodium acid decahydrate as the above-mentioned alkali metal-containing inorganic substance, the following methods are exemplified as a preferred embodiment: a furnace for forming a glass substrate and a furnace other than a quench furnace (for example, in the examples) In the large-scale tube furnace used, etc., the sodium tetraborate is vaporized at a temperature of about 850 ° C, and the vaporized substance is sprayed up to 7 Torr using a nozzle. The bottom surface of the glass substrate that is formed by the furnace or the cold furnace or the glass substrate that is transported between the crucibles. The alkali metal-containing inorganic substance is sprayed by the above method, and an alkali metal is supplied to the bottom surface of the glass substrate. The presence of the alkali metal on the bottom surface of the glass substrate can be confirmed by analyzing the underside of the glass substrate by X-ray photoelectron spectroscopy (Xps: x-ray phot 〇 electr 〇 n spectr 〇 sc〇py) or fluorescent ray ray. [Second supply step] The second supply step is a step of spraying the SO 2 gas onto the bottom surface of the glass substrate to which the metal test is applied after the first supply step, and forming a protective film on the bottom surface. This second supply step is different from the conventionally known steps of the conventional floating method in that the protective film is formed on the bottom surface of the glass substrate to which the alkali metal is supplied. In the above-mentioned second supply step, the s〇2 gas is sprayed onto the bottom surface of the glass substrate to which the alkali metal is supplied by the first supply step, and the metal is reacted with the S〇2 gas. A protective film containing an alkali sulfate salt (for example, sodium sulfate or the like) is formed on the bottom surface of the glass substrate. I22464.doc 18 For the above-mentioned second supply step, the *contacting method; *·m body attachment time (timing) and spray method can be used to exemplify the following. The time when the f is attached to the S02 gas is not particularly limited, but since it is prevented from being transported, it is preferable to consider the above: It is between the above forming step and the above-mentioned quenching step. Further, if each gas is attached, it is difficult to form a film due to a reaction between the gases, which is not preferable. On the other hand, the method of spraying the S〇2 gas can be carried out by the same method as the conventional floating method. Specifically, for example, it can be carried out by a method of spraying from a nozzle provided under the glass substrate in the width direction of the glass substrate (for example, the method disclosed in claim 12 of Patent Document 1). In the present invention, it is possible to ensure the same protective effect as compared with the prior art of using a sulfuric acid π (for example, calcium sulfate or the like) obtained from a soil-ceramic metal as a protective film for an alkali-free glass substrate. On the one hand, it reduces the injection of S02 gas by $. The reason for this is that, as described above, the s〇2 gas sprayed by the second supply is preferentially reacted with the alkali metal supplied to the bottom surface, so that the S〇2 gas and the alkali-free glass are also known. The reaction of the alkaline earth metal (Ca, Sr, etc.) which is less reactive is suppressed. Specifically, the amount of gas sprayed in the present & ming s 〇 2 gas can be reduced to 〇 5 to 2 5 L/m 2 , especially to 〇. 〇 5 to 0.3 L/m 2 . Further, it is preferred that the S〇2 gas is sprayed at a temperature within a range of 100 c of the glass transition point of the glass substrate. The reason for this is that since the glass is softened at the transfer point of I22464.doc -19-1379815, a protective film is formed in this region, whereby damage can be prevented more effectively. Specifically, the spraying of the s〇2 gas is more preferably carried out at 600 to 800 °C. The reason for this is that if the "spraying" is carried out at this temperature, the protective film containing sulfate which can be easily removed in the washing step can be efficiently produced, and the occurrence of scratches on the back surface of the glass substrate can be further suppressed. [washing step]

The above-described washing step, which is carried out as desired, is a step of washing and removing the protective film formed by the above-described second supplying step, which is a previously known step of the usual floating method. The time (timing) and the washing method of the above washing step can be appropriately exemplified as follows.

If the time of the cleaning step is later than the second supply step, there is no special limitation, but since the protective bead is set for the flaw on the surface (bottom surface) of the glass substrate during the roller conveyance process, Preferably, it is followed by the final stage of the above-mentioned cold step or the above-mentioned cold step. In addition, in the cleaning method of the above-mentioned washing step, since a protective film containing a sulfate (9) such as sodium sulfate water-salt salt derived from an alkali metal is formed in the present invention, it can be utilized. An easy way to go can be done by washing with water. Furthermore, when not implementing the glass beauty ~. When the S〇2 gas is sprayed in the case of the step, the protective film formed on the bottom surface of the glassy acid = the sulfur-soluble salt such as sulfuric acid obtained from the soil-based metal, and becomes It is difficult to easily 122464.doc -20^ 1379815 in the manufacturing method of the present invention, in order to improve the smoothness of the obtained glass-free substrate, and to reduce deformation, warpage, micro-corrugation, and flaws or foreign matter defects of the glass substrate, The surface product f having a higher uniformity may be provided with a polishing step as needed after the above washing step. This polishing step is a previously known step of the usual floating method, and as the polishing method, specifically, a method of polishing a glass substrate placed on a foamed amine group using a cerium oxide-based abrasive can be cited.

A method for producing a non-glass-based substrate according to a second aspect of the present invention is a method for producing an alkali-free glass substrate by using a floating method to produce an alkali-free glass substrate, comprising: a molding step of forming molten glass on molten tin a glass substrate; and a first supply step of ejecting a metal-containing inorganic substance 'and a second supply step' to the surface of the glass substrate on the side in contact with the molten tin at _800 kt to the first supply After the step, the SO 2 gas is sprayed onto the surface of the glass substrate on the side in contact with the (4) tin. The forming step of the second aspect of the present invention and the first aspect of the present invention In the same manner as described above, the first supply step and the second supply step are the same as those described in the first aspect of the present invention except that the f-degree is set to 6 GG to 8 GG ° C. In the second aspect, it is preferable to further include the above-described washing step, and the polishing step may be further provided. The present invention also provides a non-inspective glass substrate which is in the second aspect of the manufacturing method of the present invention. Like. The following ' In the case where the inorganic substance containing hydrazine and ^ 122464.doc 1379815 is used in the same), it is obtained by the production method of the present invention. Specifically, the inorganic substance containing Na and boron is supplied to the first one. The step is sprayed onto the bottom surface of the glass substrate, and the above-described cleaning step is carried out as needed, and an alkali-free glass substrate can be provided. The alkali-free glass substrate of the present invention preferably has the following composition. In the alkali-free glass substrate of the present invention, the glass substrate is expressed by mass percentage based on the oxide, and contains

Si02 : 30-85% »

Al2〇3 : 〇~3 5%, B2〇3 : 〇~3 5%,

MgO : 0-3 5% »

CaO : 0~3 5〇/〇,

SrO: 0~35%,

BaO: 0 to 35%, metal composition: 0 · 5 ° /. Following, and

The average boron concentration of the bottom surface of the glass substrate is a private atomic %, and the diffusion depth of boron into the inside of the glass substrate is 5 nm or more. Here, the content of Si〇2 (expressed on the basis of oxide and expressed by mass percentage) is preferably 50%, more preferably 5〇~7〇%, and even more preferably 56~66°/ Oh, especially good is 58~60%. Further, ~屮3 of 3 has 竿 (based on oxide and expressed by mass percentage), preferably 0 to Guan, more preferably 3 to 22%, and even more preferably 3 to 20%, especially good. It is 15~2〇%, and the best is 15~19%. Further, the content ratio of B2〇3 (based on the oxide [indicated by the quality " rate table 122464.doc • 22-1379815) is preferably 0 to 30%, more preferably 〇 15 15 / ( ), better is 5 to 12%. Further, the content ratio of MgO (based on oxides and expressed by mass percentage) is preferably 〇20%, more preferably 〇~8%, and even more preferably 〇~6% 〇 again, CaO The content ratio (expressed as an oxide and expressed in mass percentage) is preferably 〇20%, more preferably 〇~9%, and even more preferably 〇~8% 〇, and the content ratio of SrO ( Preferably, it is 0 to 20%, more preferably 〇~12 5%, and even more preferably 3 to 12, 5% ,, and the content ratio of BaO (in terms of oxide and expressed by mass percentage). The oxide is based on the mass percentage and is preferably 0 to 20%. More preferably, it is more than 〇% and less than 2〇/〇. Further, the content of the metal component (expressed as an oxide and expressed by mass percentage) is preferably 0.5% or less, more preferably 〇2% or less, and still more preferably 0.1% or less. The content of Si〇2, Al2〇3, B2〇3, MgQ, CaO, Sr〇, BaO and alkali metal components of the glass substrate is as described above, and is within the range of the composition of the alkali-free glass used in the alkali-free glass substrate. By. In the present invention, the average rotten concentration of the bottom surface of the glass substrate can be determined as an average value when five points are arbitrarily measured by X-ray photoelectron spectroscopy. Further, in the X-ray photoelectron spectroscopy, an X-ray spectrometer (Model 5500, manufactured by PHI Corporation) was used, and an X-ray source of monochromatic X-rays monochromated by a monochromator was used as an X-ray source. Further, the detection angle of the ray photoelectron was 75 Å, and in order to perform the charge correction, the cascade was irradiated to perform the measurement. In the present invention, the depth of diffusion of boron into the interior of the glass substrate can be evaluated by the secondary ion mass spectroscopy (MS) from the depth of the secondary ion intensity reaching the same level as the substrate. Specifically, the average value of the five-point diffusion depth was measured by a secondary ion mass spectrometer (ADEpT1®, manufactured by Ulvac 1 A) at five points on the glass substrate. Here, the sputter time is converted into a spatter depth by SiO 2 conversion (4 nm = 1 min). Furthermore, in the case where the primary ion is an oxygen ion beam, the accelerating voltage is 5 keV, the beam current is 400 nA, the incident angle of the primary ion is 45 degrees with respect to the normal to the sample surface, and the beam scanning range is 4〇〇χ4〇〇pm2. The measurement was carried out under the conditions. In the glass-free substrate of the present invention, the average thickness of the bottom surface of the glass substrate is 4 to 10% by atom, and the diffusion depth to the inside of the glass substrate is 5 nm or more and 80 nm or less. It is preferably 50 nm or less, so that the strength of the glass substrate itself is improved, and the abrasion resistance is excellent, and the scratch resistance is excellent in the transportation and processing steps after the film is removed. It is considered that the mesh structure of the glass is strong by allowing the shed to be diffused from the bottom surface to the inside of the glass substrate and remaining on the surface layer of the glass substrate to improve wear resistance and scratch resistance. The alkali-free glass substrate of the present invention does not wait until before the step of performing the above-described cleaning step, and after the above-described cleaning step is carried out as needed, boron remains on the surface layer of the glass substrate, so that the production of scratches on the back surface of the glass substrate can be continuously suppressed. .doc -24 · Health, so it is better. It is presumed that the reason why boron remains in the surface of the glass in the glass-free substrate of the present invention is that the shed easily enters the inside of the glass substrate by the first supply step, and is likely to remain on the surface layer of the glass substrate. • The present invention can also provide an alkali-free glass substrate, which is based on an oxide and is expressed in mass percent, and contains:

Si02 : 30-85% > • AI2O3 * 0~35% > B2〇3 : 〇~3 5% ,

MgO : 0-3 5%,

CaO . 〇~35%,

SrO : 〇~350/〇,

BaO: 0 to 3 5%, alkali metal component: 〇.5% or less, and the average boron concentration on the surface thereof is 4 to 1 atom. /. And the diffusion depth of boron from the surface of the crucible to the inside is 5 nm or more. [Examples] Hereinafter, the present invention will be specifically described using examples, but the present invention is not limited thereto. (Embodiment 1) The gg, =, test device shown in Fig. 2 was used. Figure 2 is a cross-sectional view of a large tubular furnace used in the embodiment. Specifically, a quartz tube is placed in a large tubular furnace having an adjustable temperature; an alkali-free glass substrate having a thickness of 0.7 mm is placed in the English s 12 122464. .doc -25· 1379815 13 (10 cm square), the large tubular furnace U is heated to 7 〇 (rc. Here, as the "alkali-free glass substrate" is used as an oxide based and expressed by mass percentage" The non-test glass consisting of: 68%$ Si〇2$8〇0/〇, 〇%^A12〇3<12% >0%<B2〇3<7%> 0%^MgO^12% ' 〇%SCa〇S15%, 0%$SrO^40/0, Oo/ogBaOgio/, and the content of the alkali component is 0.05% by mass or less. Further, the glass transition point of the glass is 700 °C. The reagent 15 of sodium tetraborate decahydrate placed in the alumina boat 14 is locally heated to about 85 (rc to vaporize it, and the vaporized material is sprayed from the end of the quartz tube in the direction indicated by the arrow 16 The steel as an alkali metal is supplied to the surface of the glass-free substrate 13. At this time, the amount of sodium tetraborate tetrahydrate is 0.4 L/m 2 'the temperature of the alkali-free glass substrate 13 7〇,〇c>c. Next, 8 〇 2 gas is sprayed from the direction indicated by the arrow 17 in such a manner that the amount of the surface of the alkali-free glass substrate .13 is 〇i L/m2 to form a protection. The film is used to produce an alkali-free glass substrate with a protective film. The temperature of the alkali-free glass substrate 13 at this time is 7 〇〇. Further, the conditions of the present embodiment and the above-mentioned forming step and the above-mentioned cold After the alkali metal-containing inorganic substance was sprayed between the steps, the conditions for spraying the gas of s〇2 were the same. (Example 2) The same as Example 1 except that the amount of the S02 gas sprayed was set to 〇4 L/m2. The method is to produce an alkali-free glass substrate with a protective film. (Example 3) Except that the S 0 2 gas is a < 1 λ τ / 2 and the spray 5 is 丨.0 L/m, Manufactured in the same manner as in Example 122464.doc -26-1 (Comparative Example 1) Except that the tetraboron inversion was not used, _^7廿+^ 1 The same square is used to make the alkali-free glass substrate with the protective film attached. (Comparative Example 2) ', the sodium tetraborate is not used, and only s〇2 is sprayed. A glass-free substrate with a protective film was produced in the same manner as in Example 2 except for the gas.

(Comparative Example 3) > An alkali-free glass substrate with a protective film was produced in the same manner as in the case of real J3 except that sodium tetraborate was not used and only s〇2 gas was sprayed. (Comparative Example 4) The s〇2 gas was not sprayed but only 7 Å except that sodium tetraborate was not used. An alkali-free glass substrate was produced in the same manner as in Example 1 except that the crucible was heated for 15 minutes. (Comparative Example 5)

There is an alkali-free glass substrate that protects the bedding. An alkali-free glass substrate was produced in the same manner as in Example 1 except that sodium tetraborate was not used and s〇2 gas was not sprayed. By the method shown below, the adhesion of the protective film, the damage resistance, the average boron concentration, the diffusion depth, and the wear resistance of the protective film of the non-glass-coated substrate each having the smear-protected film obtained in Example U and Comparative Example U were used. Sex determination and S parity. The results are disclosed in Table 1 below. Further, the glass substrates for the flat panel glass obtained in Comparative Examples 4 and 5 were not sprayed with the S〇2 gas, and the protective film was not formed. Therefore, only the abrasion resistance was obtained by the method described below. The measurement was carried out. The results I22464.doc • 27· 1379815 are disclosed in Table 1 below. <protection film adhesion amount> The protective film of the obtained alkali-free glass substrate with the protective film obtained was dissolved in pure water, and lCP (lnduCtively plasma) emission spectroscopy was used to sulphur Quantification was performed and sodium was quantified using atomic absorption. Based on the quantitative values, the amount of the adhered sodium sulfate was calculated as the adhesion of the protective film. The amount of adhesion was determined as the average value calculated from the obtained one-piece alkali-free glass substrate. <Injury" The evaluation of the scratch resistance was carried out by using the test according to JIS R3221 (199 years). Further, the Taber test was carried out under the conditions of a Tdedyne Taber Model 503, a wear wheel fixed to cs_1〇F, a load of 250 g, and a fixed number of wear times of three times. Thereafter, in order to remove the protective film used as the alkali-free glass substrate with the protective film as the test body, the substrate was washed with water under a stream of pure water (3 liters/min) for 30 seconds. The surface of the obtained glass substrate from which the protective film was removed was observed with a microscope, and the number of scratches (the number of flaws) in the length of 1 cm x ! cm and the length in the long axis direction of 〇 2 mm or more was measured. The measurement unit is a central portion of a portion for Taber test (see Fig. 3). In Fig. 3, the wear portion is formed by the wear wheel in the test body (..., alkali glass substrate) 8 and the measuring portion 2 is the central portion of the wear portion 19. Further, the measurement of the number of scars was carried out on any of the respective glass substrates of 122464.doc -28- 1379815, and the average value thereof was determined. Further, the number of damage occurrences was obtained as an average value calculated from the obtained ten glass substrates. <Average boron concentration. Diffusion depth> (1) The obtained alkali-free glass substrate with the protective film obtained was washed with water at a place where 2 (TC pure water (flow rate '·3 liter/min) was poured, The protective film was removed. Then, the average value of the boron concentration on the surface of the glass substrate after the cleaning was determined as an average value measured by X-ray photoelectron spectroscopy at five points. Further, in X-ray photoelectron spectroscopy Using an xps spectrometer (Model 55, manufactured by PHI), the X-ray source is monochromated by a monochromator, and the detection angle of the X-ray photoelectron is 75. In order to perform charging correction, the cascade is irradiated and the measurement is performed. (2) The depth of diffusion of boron into the glass substrate is secondary to the depth of secondary ion intensity equivalent to the substrate by secondary ion mass spectrometry (SIMS). Start the assessment. Specifically, §, using a secondary ion mass spectrometer (ADEpT1〇i〇,

The Phi company's product) measured the diffusion depth of the point at 5 points on the cleaned glass substrate, and determined the average value. Here, the sputter time is converted into a spatter depth by using sia conversion (4 nm = 1 min). Furthermore, in the primary ion is an oxygen ion beam, the accelerating voltage is 5 kev, and the beam current is 400 nA'. The incident angle of the primary ion is 45 degrees with respect to the normal to the sample surface, and the beam scanning range is 40〇χ4〇〇μηη2. The measurement was carried out under the conditions. In Table 1 below, the diffusion depths of Comparative Examples 1 to 3 were "-", indicating that diffusion could not be confirmed. <Abrasion resistance> 122464.doc •29- 丄:)丄2) Abrasion resistance I& 左 Left is also measured by the rate of change of turbidity rate before and after the Tabe1j test (turbidity change rate) ongoing. 5 The turbidity rate of each non-inspected glass substrate obtained by the measurement of the enthalpy meter. Then, each of the obtained alkali-free glass substrates was subjected to a Taber test in accordance with JIS (9 years). Further, the Taber test was carried out using a Taber tester (Tdedyne Taber M〇del 5〇3), and the wear wheel was fixed to a condition that the load of cs_φ 10F' was fixed at 5 〇〇g. Then, the turbidity rate after 1000 times of Taber abrasion was measured by a turbidimeter. The rate of change was determined from the turbidity rate before the Taber test. Here, the haze value can be defined as follows by using scattered light (Td) and transmitted light (Tt). Turbidity rate = (Td / Tt) x l00% Further, the rate of change (ΔΗ) of the turbidity rate (Η) can be expressed by the following formula. △ Η = turbidity rate after 1000 times of abrasion turbidity rate before H-Taber test • Η [Table 1] 122464.doc 30- 丄:) Table 1 '---- sodium tetraborate spray amount (L /m2) So2 gas spray amount (L/m2) Protected film adhesion amount (mg/10 cm square) Damage resistance number (units / 10 cm square) Average boron concentration (at%) Diffusion depth (nm) Resistance Abrasion turbidity change rate (%) Lean application 1 0.4 0.011 0.011 12 7.4 10 2.3 Example 2 0.4 0.4 0.035 1 7.4 10 2.3 Lean application 3 0.4 1.0 0.058 0 7.4 10 2.3 Comparative Example 1 0.1 — 0.010 24 3.1 3.4 Comparative Example 2 0.4 0.011 10 3.1 3.4 Comparative Example 3 1.0 0.011 5 3.1 3.4 Comparative Example 4 Comparative Example 5 -- _ - - - 3.2 3.3 ..- sucking the corpse / r after the application of the case 曰 ' _ glass The substrate was effectively formed with a protective film even when compared with the comparative examples] to 3, even if the gas was sprayed to be equal or lower. Further, it has been found that the boron concentration is also improved, and the scratch resistance is also particularly excellent. Further, in Comparative Examples 1 to 3, although the amount of sodium sulfate was equivalent, the number of scars was decreased as the amount of the two gas sprayed was increased, because the sulfate derived from the alkaline earth metal was formed. (calcium sulfate, barium sulfate, etc.), and these functions as a protective film. Further, it has been confirmed that the alkali-free glass substrates of Examples 1 to 3 are usually washed with water, and the protective film formed on the surface of the glass substrate is removed to exhibit a clean surface. On the other hand, in the case of the alkali-free glass base of the comparative examples i to 3, 122464.doc 1379815, the protective film formed on the surface of the glass substrate could not be removed and left. Further, when the film component remaining is measured, it is calcium sulfate and barium sulfate. Further, it is known that the alkali-free glass substrates of Examples 1 to 3 have a reduced turbidity change rate and an improved wear resistance as compared with the alkali-free glass substrates of Comparative Examples 1 to 5 due to boron diffusion. The present invention has been described with reference to the particular embodiments of the invention, and the invention may be modified or modified without departing from the spirit and scope of the invention. The present application is based on a patent application filed on Jul. 7, 2006, the entire disclosure of which is hereby incorporated by reference. [Industrial Applicability] According to the present invention, it is possible to provide a protective film which can be easily removed in the washing step, thereby achieving a reduction in the amount of sulfur dioxide used, and suppressing the occurrence of damage on the back surface of the glass substrate. A method for producing an alkali-free glass substrate, and an alkali-free glass substrate obtained by the method. The alkali-free glass substrate of the present invention can be suitably used in a high-quality display. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a conceptual diagram showing an example of a glass manufacturing line using a floating method. Figure 2 is a cross-sectional view of a large tubular furnace used in the examples. Fig. 3 is an explanatory view showing a portion (abrasion portion) touched by the abrasion wheel of the Taber test machine used for the evaluation of the scratch resistance, and a measurement portion (measurement portion) of the number of damages. 122464.doc •32· 1379815

[Main component symbol description] 1 Molten tin 2 Molten tin bath 3 Melting kiln 4 Brilliant glass 5 Guide roller 6 Xu cold furnace 11 Large tubular furnace 12 Quartz tube 13 No glass substrate 14 Emulsified Ming Jing Zhou 15 Reagent 16, 17 Arrow 18 Test Body 19 Wear part 20 Measuring part 122464.doc •33 ·

Claims (1)

1379815 十, _ 年月曰!f (more) is replacing the second recession patent application No. 2.^ ―" --1 Chinese patent application scope replacement 4^ (August 101), A please insult range: A method for producing an alkali-free glass substrate, which is a method for producing a glass-free substrate by a floating method; comprising: a molding step of forming molten glass on a molten tin into a glass substrate; and a step of cooling The glass substrate formed by the forming step is cold-cooled, and includes a first supply step of spraying an inorganic substance containing an alkali metal onto a surface of the glass substrate on the side in contact with the molten tin, and a second supply step. After the first supply step, the SO 2 gas is sprayed onto the surface of the glass substrate on the side in contact with the molten tin. 2. The method for producing an alkali-free glass substrate according to claim 1, wherein the first supply step is performed between the forming step and the quenching step; 3. The method for producing an alkali-free glass substrate according to claim 1, The first supply step is carried out at a temperature within a range of ±100 ° C of the glass transition point of the glass substrate. 4. The method for producing an alkali-free glass substrate according to claim 1, wherein the first supplying step is carried out at 600 to 8 °C. 5. The method of producing an alkali-free glass substrate according to any one of claims 1 to 4, wherein the second supply step is performed between the forming step and the quenching step. The method for producing an alkali-free glass substrate according to any one of claims 1 to 4, wherein the second supply step is carried out at a temperature within a range of ±10 〇C of the glass transition point of the glass substrate. 7. The method for producing an alkali-free glass substrate according to any one of claims 1 to 4, wherein: 122464-1010822.doc 1379815 (a) year 'the sleeve is replacing the page. The second supply step is 6 〇〇~ 8〇〇t: Under implementation. 8. A method for producing an alkali-free glass substrate, which comprises producing a non-alkali glass substrate by a floating method, comprising: forming a molten glass on a molten tin to form a glass substrate; 1 supply step 'at 600~800. (: the inorganic substance containing the metal to be inspected is sprayed onto the surface of the glass substrate on the side in contact with the molten tin; and the second supply step 'after the first supply step, the glass is applied to the glass at 600 to 800 ° C The surface of the substrate on the side in contact with the molten tin is sprayed with the so2 gas. The method for producing an alkali-free glass substrate according to any one of claims 1 to 4 and 8, further comprising the step of removing the protective film The method for producing an alkali-free glass substrate according to any one of claims 1 to 4, wherein the alkali metal-containing inorganic substance contains sodium and boron. 11. The manufacture of the alkali-free glass substrate according to claim 10. The method wherein the inorganic substance containing the metal detector is sodium sulphate. 12. An alkali-free glass substrate produced by the method of claim 7 or the method of manufacturing. 13. an alkali-free glass substrate, It is manufactured by the manufacturing method of the claim (7) or the above-mentioned glass substrate, which is represented by mass percentage, and contains: Si〇2: 30 to 85%, Al2〇3: 0 to 35%, B2O3 · 〇~35% > I22464-1010822.doc 1379815 New Year's Heart Repair (Imperial Digestion I MgO: 0~35%, CaO: 0~35%, SrO: 0~35%, BaO: 0~35%, Alkali Metal Composition: 0.5% or less, the surface of the glass substrate on the side in contact with the molten tin has an average boron concentration of 4 to 10% by atom, and the diffusion depth of boron into the glass substrate is 5 nm or more. 122464-1010822.doc