TW201014810A - Method for producing flat glass - Google Patents

Abstract

A method is described for producing flat glass, in which glass is melted in a melting tank and the glass melt is poured onto a liquid metal bath contained in a float bath housing and shaped to form a glass ribbon, a protective gas containing hydrogen being introduced into the free internal volume of the float bath housing and discharged from the float bath housing. At least 0.2 Nm<SP>3</SP>/min of the protective gas is introduced per m<SP>3</SP> of the free internal volume of the float bath housing. Complete replacement of the entire protective gas volume contained in the float bath housing is carried out in a time tav, theo ≤ 1.2 minutes.

Description

201014810 VI. Description of the Invention: [Technical Field to Be Invented by the Invention] The present invention relates to a method for producing flat glass according to the scope of the patent application. [Prior Art] The flat glass produced by the float process is called float glass, and the process technology is mainly based on the patent issued by pukingt〇n (US 3, 083, 551, DE 147 1 9 50), and has been developing since the last century, and is now known as a system of law. In the floating process, a liquid glass is injected into a molten metal bath from a working tank by a passage, and the metal is usually tin. With the setting of a movable gate, not only the flow rate of the liquid glass can be controlled, but also the thickness of the glass can be controlled. Observing the direction of the flow of the liquid glass, 'the above movable gate is one; the main inlet, the liquid glass is continuously injected into the molten metal bath through the injection port' and is shaped and solidified in the molten metal bath To form a fixed-size glass ribbon. Subsequently, in order to take out the solidified glass ribbon from the molten metal bath, a lifting device (Hf1; ing instrument) is required after the floating bath. The flat glass produced by this method is generally thick. Less than millimeters (mm) is often used as a thin glass substrate, especially for the manufacture of flat panel displays such as plasma display panels (201014810 PDPs), field emission displays (Fieds-emission displays, FEDs), 溥Thin film transistor (TFT) liquid crystal display screen, super-twisted nematic (STN) liquid crystal display screen, plasma-assisted liquid-crystal (PALC) display, and electroluminescence (eiect rolumine scent, EL) displays, etc., can also be used to manufacture thin film solar cells. In the process of a flat panel display, depending on the type of display, φ can be used to fill a liquid crystal molecule between two glass plates, or a dielectric layer can be applied to the front side and the front of the rear glass sheet. The back side of the front sheet and the dielectric layers are used to form lattice cells that can accommodate the phosphor. In order to avoid the occurrence of perturbing colour deieets or similarity deviations, it is important to accurately maintain the thickness of the liquid crystal material layer or dielectric layer, especially for large-sized flat panel displays. Since the thickness of the material layer (currently about 3 〇 micro ® meters) tends to be thinner, and the size of the display is gradually larger, the precise control of the above conditions becomes more important. The surface quality of floating glass is reduced by surface defects, which are called top specks, mainly because of the tin-containing particles (such as kick or tin oxide particles) when using a molten tin bath. Deposited on the upper surface of the glass ribbon to form a foul. Although the process will flush the interior with a forming gas (typically 5 - 8% hydrogen, the rest being nitrogen). However, the air above the floating bath still has oxygen, and the residual oxygen will enter the molten tin bath. Tin oxide particles are formed therein. With the increase in bath temperature in 201014810, tin oxide or tin will evaporate and come into contact with air, causing particles containing tin to deposit on the upper surface of the glass ribbon to form a foul. In order to avoid the above surface defects, various methods must be used to prevent the glass ribbon from coming into contact with the contaminated air above it. - In terms of oxygen, it is not possible to enter the inside of the float bath h〇using from the outside, and the existing oxygen cannot enter the molten tin bath to contact its surface. In addition to surface defects, open bubbles caused by a protective atmosphere above or below the glass ribbon may occur on the bottom side of the ribbon. At the beginning of the shaping, the viscosity of the glass melt is very low, and an open-bottomed bubble formed under the glass is pressed into the glass by being squeezed by the gas. In the curing step, the open cells are retained and form defects of the glass. Such bubbles are also known as bottom open seed (BOS). Current Alkali-free speeial glass (for example, glass for LCD displays) is also manufactured by a floating method. Since a fine electronic structure is applied to the surface of the glass, even a small surface defect causes a problem. In general, the open-ended bubble has a diameter of less than 50 microns and a depth of less than 1 〇 microns. These open cells can be removed by grinding. However, this final grinding step also requires a lot of expense. US 20 04/01 1 0625 A1 discloses that the bubbles located on the bottom side of the glass are the result of interactions between the water escaping from the glass. The reason why this moisture cannot be dissolved in the molten tin is due to the concentration of hydrogen in the molten tin. Too high by 201014810. The diffusion of water in the glass is affected by the field strengths of the glass. By adding titanium dioxide (Ti〇〇, erbium oxide or neodymium) to increase the field strength, water diffusion can be reduced, thereby reducing the occurrence of defects. US 20 04/0107732 A1 discloses a method for floating baths The concentration of helium in the atmosphere in the hot zone is adjusted to less than 3% to avoid the occurrence of bubbles disclosed in us 2004/01 1 0625 A1. This method can reduce the concentration of hydrogen in the molten tin of φ and thus diffuse from the glass. Hydrogen can be dissolved in molten tin to avoid the generation of bubbles. In contrast to this prior art, US 3, 337, 322 discloses a protective gas atmosphere containing more than 5% of inert gas body 'the rest Part of it is a reducing gas, especially hydrogen. This patent discloses that the preferred composition of the protective atmosphere is 85% nitrogen and 15% hydrogen; 3-10% hydrogen, the rest is nitrogen; 2-8% hydrogen, The remainder is nitrogen; and 0.25-(10) hydrogen, the remainder being nitrogen. Especially when the hydrogen® gas content in the protective atmosphere is low, an environment of different hydrogen concentrations can be established inside the floating bath enclosure. US 5, 364, 435 discloses a The present invention provides a method for producing flat glass, comprising the steps of: placing a glass in a melting tank to obtain a glass melting. (glass melt); pouring the glass melt into a liquid metal bath 7 201014810 (liquid metal bath) and shaping the glass melt to take a glass ribbon, wherein the liquid metal bath is located a floating bath housing having a free internal volume; introducing a chlorine-containing protective atmosphere into the free internal volume of the floating bath cover, followed by the hydrogen containing The protective atmosphere is evacuated to the outside of the floating bath cover, wherein the flow rate into the protective atmosphere is 'at least 0.2 standard cubic meters per minute (^1) for each cubic volume of the floating bath cover. min [Embodiment] The purpose of the invention is to reduce the number and size of the bottom surface seed and the bottom 种pen seed (B〇s). The i-th term can achieve the purpose of the invention. The unit "N," is called the standard cubic meter of the protective atmosphere (4). The standard cubic system refers to a cubic meter of gas at the absolute force UI325 bar, the degree of fishing &quot; The amount measured under conditions of temperature and hunger (in accordance with ISO 2533). / Free moving inner volume of the bath housing (free inf al V〇1 滕 refers to the volume inside the housing of this * dynamic bath, which can be filled with a protective atmosphere, ^: used on the surface of the glass ribbon or above the surface of the molten tin bath Fix the heater under the suspended top cover. The internal atmosphere, introduce) the protective atmosphere, and for a floating bath cover per cubic meter, the self-flow rate is at least 0.2 standard cubic meters / minute min 201014810 at the same flow rate (gas volume / unit time The protective atmosphere is withdrawn from the floating bath cover to replace the protective atmosphere.疋 In the average theoretical replacement time tav, the. In the time of less than or equal to 12 minutes (purely calculated), the protective atmosphere equivalent to the freedom of the military outside the floating bath was replaced. ° In order to calculate the average theoretical replacement time t—(in minutes), divide the free internal volume (in cubic meters) by the atmospheric flow rate (in cubic meters) applied in the operating state • (〇Peratlng state) /minute). According to the convention, the atmospheric flow rate measured in the standard state is marked as L.S, and the early position is standard cubic meter/minute and one minute in order to calculate enthalpy. Relationship with 吖5 'The atmospheric flow rate Ls measured under standard conditions must be multiplied by the average absolute temperature τ~ν of the atmosphere in the floating bath (in hunger temperature κ)' and divided by the absolute temperature of the atmosphere under standard conditions. Ti.s. (in accordance with IS〇2533, n 288 15Κ). • The following relationship is therefore available: &quot;tev, theo

V

Free, FB iO sub-i.sTWav This case has proved that the rapid replacement of the atmosphere in the bath helps to reduce the surface stain and the bottom opening seed core 0-openseed, 卜min, floating, cubic meter (m3) The bath cover has a free internal volume and the flow rate of the protective atmosphere is preferably at least 0.23 standard cubic meters per minute JVm3.), preferably more preferably at least 0.26 standard cubic meters per minute.

Nm3 min at least 0.28 standard cubic meters per minute 9 201014810 It has also been demonstrated in this case that the protective atmosphere is continuously replaced by a volume of at least 8〇% of the free internal volume of the floating bath cover. Depending on the setting and operating position of the inlet and outlet of the protective atmosphere, at least 80% of the floating bath outside may be a change due to a fixed area inside the floating bath cover (for example, may migrate during operation) position). In order to avoid the accumulation of contaminant particles in the dead v〇lumes, the average theoretical replacement time tavthe of the protective atmosphere volume in the outer casing of the oceanic moving bath is completely replaced. It is preferably controlled to be 1.2 minutes or less ($12 min). Furthermore, it is preferred that all free internal volumes participate in the process of protecting the atmosphere. The fact that all free internal volumes participate in the protective atmosphere replacement process does not indicate that the replacement process without any internal volume is relatively fast, nor does it mean that the replacement process without any internal volume is slow. The process of protective atmosphere replacement preferably has at least 80% of the free internal volume having the same displacement velocity. It has also been demonstrated in this case that for a free internal volume of a floating bath enclosure per cubic meter (m3), when the flow rate of the protective atmosphere is at least 标准2 standard cubic meters per minute (^) and is withdrawn at the same flow rate The protective atmosphere replacement process in different regions with different replacement speeds should be harmless for the process. The introduction and/or extraction of the protective atmosphere can be carried out in a continuous or pulsed manner. In addition, 'in this case, it has also been confirmed that in the first half of the floating bath cover 201014810: the floating cubicle cover of the female cubic meter (ffl) is free from the internal volume and the flow rate is at least 〇 2 standard cubic meters / minute (^) &amp; min ^ atmosphere ' should be beneficial to the process. — The flow rate of the protective gas t can be reduced by, for example, half of the floating bath. P (ie hot zone) increases the flow rate into the protective atmosphere, for example, the free internal volume flow rate per cubic meter (m3) of the floating bath cover is standard cubic meters per minute (=_); in other areas it can be reduced The flow rate of the protective rolling mill is introduced, for example, for a free internal volume of the floating bath cover per cubic meter (ffl3), the flow rate is 0.15 standard cubic meters per minute (^). Only min ', text can ensure that the floating bath cover per cubic meter (Π) 3) free internal avoidance, the average flow of the protective atmosphere is at least G.2 standard cubic meters / minute (:). The process of introducing the protective atmosphere into the floating bath cover is preferably introduced at a uniform speed in this space. In the present case, the protective atmosphere is introduced at a uniform speed and through the entire sub-moving slot' preferably, at a uniform speed, the protective atmosphere is passed through the suction device on the floating bath wall (also known as the exhaust device, Veirting-out instruments). The floating bath can be divided into a plurality of floating bath zones (n〇at 讣 sections). This floating bath zone can also be referred to as bays. In each of the floating bath zones, it is preferred to introduce and evacuate the protective atmosphere at the same flow rate (flow rate/unit time). According to the size of the floating bath in this case, in order to make the protection atmosphere replacement time between 201014810 less than or equal to 1.2 minutes (S 1 · 2 in i η ), it is necessary to introduce a shielding gas with a flow rate of preferably up to 1 000 standard cubic meters per hour. Floating bath cover. Compared with the protective atmosphere replacement time of about h5 minutes, by controlling the protective gas replacement time of 1.2 minutes or less and 1.2 minutes, the number of defects and bubbles can be reduced by 60%. Preferably, the protective atmosphere replacement time is less than or equal to j knives min), and the optimum is less than or equal to 〇·8 minutes (SO. 8 min), and the number of defects and bubbles will be reduced with the protective atmosphere replacement time. reduce. According to the prior art, the content of argon in the protective atmosphere is between 10 and 12%. The case found that when the hydrogen content in the protective atmosphere is increased to more than 12%, it will enhance the positive impact of the rapid replacement of the protective atmosphere on the process. The content of hydrogen in the protective atmosphere is preferably greater than 12% to 14% (&gt; 12 _ 14/〇. For the floating bath zone located in the hot zone of the first half of the floating bath, the content of hydrogen in the protective atmosphere is preferably Between m and 14% 〇Η. Therefore, the density of the bottom open seed core (B0S) can be greatly reduced by this method. As shown in Fig. 1, for the floating bath cover per m ^ 3 free ® When the volumetric introduction flow rate is 0.23 standard cubic meters per minute (3⁄4 of the protective min atmosphere, and the content of hydrogen in the protective atmosphere is 5%, the average percentage of the number of bottom open cores (B0S) is determined to be about. However, when the atmosphere is protected When the content of medium gas increases by Yuan 1 q # is 13·5/°, the average percentage of the number of open end seed nucleus (B0S) is reduced to about 30%. Fig. 2 shows the plate surface area per square meter. Percentage of contamination is plotted against time 12 201014810. During the first 5 weeks, the floating bath cover of the parent cube is measured from the internal beta volume, and the average flow rate of the protective atmosphere is 〇9 standard cubic meters per minute (^). Theoretical replacement time ". two clocks; product, with double eyes The internal core material Η Η 体积 体积 Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η Η The η 1 ^ US map can confirm that the board surface stain number is significantly reduced by at least 80%. The above percentage is the relative ratio of the average values at each specified time. - The number of board surface stains in addition to hydrogen in the time interval The protective atmosphere also includes a nitrogen, helium and/or xenon. 'It is preferred that the method of the present invention is particularly suitable for the production of acid and acid, such as the application of the crucible (the number behind the component represents the weight percentage of the oxide) ): Si02 70 _ 8 ... τ .... 85 β2 〇 3 7 - 13, Na2 〇 + (4) -8, _ + Ca0 + Sr00, 3, Ai2 〇 32_7. Another example is no inspection ^ (4) reading glass, its composition includes :sim H, Al2〇3l0-25, Mg〇〇_1〇, Ca&quot;_i2, w 〇-12二〇〇一15, and such as + _ + _ + _8_ 2 -1°, Zr〇2°-5 'Ti〇2°~5, Sn〇2.-2. Another example is the use of glass for making money' including the following composition: siQ2&gt;55_65, β2〇3 5 — U, Al2. 3>14 — 25, _ 0 -8, Ca 〇〇 8 SrOO-8 gt; BaO, l 〇 ^ ^ Mg 〇 + Ca 〇 + Sr 〇 + Ba 〇 8 13 201014810 21, ZnO 〇 - 5, Zr 〇 2 〇 _ 2, Ti 〇2 0 - 3, Sn 〇 2 0 - 2 ; particularly including the following composition: Si〇2 &gt; 58 — 65, B2〇s &gt; 6 - l〇. 5, A1z〇3 &gt; 14 - 25, MgO 〇- &lt; 3, CaO 0 - 9, BaO &gt; 3 - 8, and MgO + CaO + BaO 8 - 18, ZnO 0 - &lt; 2, no As2〇3, no Sb::〇3 ' It is free of zinc oxide (Zn 〇xide), cerium oxide (ce 0Xlde), Zr oxide, and titanium oxide (Ti oxide). The method is particularly suitable for the manufacture of various green glasses for glass-ceramic, and the composition thereof includes: Si〇2 55 _ 69, 19 -25, Li 2 〇 3 - 5, Na 2 〇〇 - 1.5. K2〇0 - 1, 5, work + K2〇0.2-2'Mg00.1-2.2'CaOO-15'SrO〇- BaO 0 - 2. 5, Σ MgO + CaO + SrO + BaO &lt; 6, ZnO 〇 One

Na2〇 1.5, 1.5,

Ti〇2 into:

TiCh 1 - 5, Zr〇2 Bu 2. 5, Sn〇2 0-&lt; 1, Σ

Sn〇2 2· 5 - 5, P2〇5 〇 - 3 ; or have the following groups

Si〇2 55 -69 A 1 2〇3 19 -25 Li2〇3. 2 -5 Na2〇0 _ -1.5 K2〇0 - 1.5 MgO 0 - 2. 2 CaO 0 - 2. 0 SrO 0 - 2. 0 BaO 0 - 2. 5 ZnO 0 - &lt; 1. Ti〇2 0 - 3 14 201014810

Zr〇2 1

Sn〇2 0. 1 - &lt; i Σ Ti〇2 + Zr〇2 + Sn〇22. 5-5 P2O5 O-3 F 0-1 B2O3 0-2

Nd2〇3 0. 01 - 〇. 6

Or a glass-ceramic precursor glass comprising: Si 〇 2 55 -75, AI2O3 15 - 30, LhO 2. 5 - 6, Σ Na2 〇 + K2O &lt; 6, Σ MgO + CaO + SrO + BaO &lt; 6 ' B2O3 0 - &lt; 4 ' Σ Ti〇2 + Zr〇2 &lt;2. Or a glass-ceramic precursor glass, the composition of which includes:

Si〇2 60 - 72, Al2〇3 18 - 28, U2O 3 - 6, Σ Na2〇 + K2O 0.2-2, Σ MgO + CaO + SrO + BaO &lt; 6 ' ZnO 0 - 1· 5, B2〇3 0 -&lt; 4, SnO 0. 1 - 1· 5, x Ti〇2 + Zr〇2 &lt; 2, P2〇5 〇_3'F〇-2° Other suitable for manufacturing by the method provided by the present invention The glaze comprises: glazing glass having at least 55 wt% SiCh, preferably at least 60 wt%, and most preferably 64 wt%. Wherein Si (the upper limit of h is 7〇% by weight, preferably less than 68% by weight, most preferably at most 67% by weight. (4) The acid glass is still packaged...she is ..., preferably up to 5 wt%, And the minimum content of 40%. The maximum content of Βζ〇3 of the (4) acid glass is 2% by weight, and preferably 15% by weight. 重量% by weight or more; 2〇3, more than 20% by weight; and αι2 〇3 max. The aluminosilicate glass further comprises at least 18% at least 19% by weight, and most preferably at least 15 201014810 content is 25% by weight, preferably 24.5% by weight, and most preferably 24% by weight of the aluminophthalic acid The glass further comprises from 3 wt% to up to 5% by weight of Li2〇, the minimum content of Li2〇 is 3.25 wt%, and preferably 3.5 wt/〇; and the maximum content of Li 2〇 is up to 5% by weight, preferably at most重量重量。 The upper limit is at most 4.75% by weight, and most preferably at most 4.6% by weight. The aluminite glass further comprises 0% by weight to up to 3% by weight of Na2 〇 and K2O, wherein The upper limit of the Na2 content is at most 1.5% by weight, preferably at most 1% by weight; and the maximum content of K2O is 1.5% by weight, preferably 1% by weight. The total content of the metal oxides, the total content of the metal oxides, from 0% by weight to at most 3% by weight, the minimum total content is 0.25% by weight, preferably 0.5% by weight, and the maximum total content. The content of 5% by weight, preferably 2.75% by weight, and most preferably at most 2.5% by weight. The aluminosilicate glass further comprises CaO and SrO, wherein the contents of CaO and SrO are independent of each other, respectively 0% by weight. 5%。 The maximum content of CaO and SrO is preferably 2% by weight, preferably 1.5%, respectively. % by weight. The aluminosilicate glass further comprises from 0% by weight to up to 3% by weight of Ti〇2 and from 1% by weight to at most 2.5% by weight of 21*〇2, wherein the minimum content of Ti〇2 is 0.5% by weight. Preferably, the content of Ti〇2 is 2.75% by weight, most preferably 2.5% by weight, and the minimum content of Zr〇2 is preferably 1.5% by weight; the maximum content of Zr〇2 is 2.25. % by weight, preferably 2% by weight. The aluminosilicate glass further comprises from 0.1% by weight to at most 1% by weight of Sn 〇 2, wherein the minimum content of Sn 〇 2 0. 15% by weight, preferably 16 201014810 0.18% by weight; The maximum content of SnOz is 〇·9% by weight 'optimally 0.8% by weight. In this name acid glass, 'oxide Ti〇2, Zr〇2 And the total content of Sn 〇 2 is at least 2. 5 wt% to at most 5% by weight 'minimum total content is 3% by weight, most preferably 3.25 wt%; and the maximum total content is 4.9 wt%, most preferably at most 4. 8 wt%. 5重量%。 The content of the BaO content is 0% by weight to 2.5% by weight, and the content of BaO is 0% by weight to 2.5% by weight. . In the aluminosilicate glass, the minimum content of MgO and BaO is 〇. 〇 5% by weight, preferably the minimum content is 0.1% by weight, respectively, and the preferred maximum content of MgO and BaO is 2% by weight, respectively. The aluminosilicate glass further comprises ZnO and/or P2〇s, and the contents of ZnO and/or P2〇s are independent of each other and can be adjusted as needed, wherein the ZnO content is from 0% by weight to less than 5% by weight, and the p2〇5 content is 〇% by weight to 3 parts by weight, wherein the minimum content of ZnO is preferably 〇〇5% by weight, most preferably 0.1% by weight; the maximum content of ZnO is preferably [% by weight, • optimally 〇.75% by weight. The minimum content of P❿ is preferably 0.5% by weight, most preferably 1% by weight; the maximum content of P2〇5 is 2.5% by weight, most preferably 2% by weight. The aluminosilicate glass further comprises d1% by weight to 〇6% by weight of Nd2〇3, and the minimum content of Nd2〇3 is preferably 〇〇5% by weight, most preferably % by weight; and the maximum content of NchCh is better* 〇 Σς 旦 η / π double live horse ϋ. 55% by weight, preferably 0.5% by weight. The present invention has been described as a preferred embodiment, and the present invention has been described in terms of several preferred embodiments, which are intended to be within the scope and spirit of the invention. , when can be 17 201014810 decorated 'so the protection of the invention (four) is defined by the scope of the patent after the m ★ patent. [Simple description of the figure] The first circle is the average percentage of the number of bottom open seed nucleus (B0S) 舆 time relationship diagram ' to illustrate the achievable effect of the present invention. The second step is the percentage and time of a board surface stain to illustrate the achievable effect of the present invention. ^

[Main component symbol description] None

18

Claims (1)

201014810 VII. Patent application scope: 1. A method for manufacturing flat glass, comprising the following steps: placing a glass in a melting tank to obtain a glass melt; pouring the glass melt Into a liquid metal bath and shaping the glass melt to form a glass ribbon (where the liquid metal bath is located in a floating bath housing, and the float The bath cover has a free internal volume; a protective atmosphere containing hydrogen is introduced into the free internal volume of the floating bath cover'. The protective atmosphere containing the crucible is then withdrawn to the outside of the floating bath enclosure, wherein each cube For the internal volume of the floating bath cover of the meter, the flow rate into the protective atmosphere is at least 〇·2 standard cubic meters per minute (:^). Min 2. The method for manufacturing the flat glass according to the scope of the patent application, wherein the flow rate of the protective atmosphere is at least G. 23 standard for the internal volume of the floating loft cover per cubic meter. Cubic meters / minute (^1). Min 3· As in the manufacture of flat glass described in the first or second paragraph of the patent application, the flow rate of introducing the protective atmosphere to the internal volume of the floating bath cover per cubic meter is At least 02 m / min (^1). Min 2 is the method of any of the items i to 3 of the patent application scope, wherein the protective atmosphere is introduced into the standard cubic meter per minute (M) for the internal volume of the cover 19 201014810 per cubic meter of the float tank. ). ^ ^ °*28 min 5·If you apply for a patent range! The method for fabricating a flat glass according to any one of the items 4 to 4, wherein, in the floating squeezing, the average theoretical replacement time t~ of the protective atmosphere volume in the grooved cover is replaced by the element. Less than equal minutes. The method of producing a flat glass according to claim 5, wherein the protective atmosphere is continuously replaced with a volume of at least 80% of the volume of the floating bath cover. 7. The method for producing a flat glass according to any one of the preceding claims, wherein the introduction of the protective atmosphere is carried out in a continuous or pulsed manner. f 8· The method for manufacturing a half-panel glass according to any one of the claims of the invention, wherein the protection and the ceremonial 疋Μ 疋Μ 每 每 每 每 每 3 3 3 3 3 3 Volume and a (4) 3 U. 2 standard cubic meters / minute (1 ^) flow rate into the front half of the floating bath cover. 9. In the method of making the glass of the first to eighth items of the patent application, the protective atmosphere is introduced into the floating bath cover in a uniform manner. 10. The method of making the i-th to the ninth flat glass of the patent scope, in the same flow rate (flow/unit time n, λ λ * s s) 'In phase time' is introduced and extracted from the protective atmosphere. 11. For the production method of 20 201014810 flat glass as described in any of the scope of the patent application, item 12%, 12%. The hydrogen content in the protective atmosphere is greater than 12. The production of the flat glass described in the above-mentioned patent application, wherein the hydrogen content in the protective atmosphere is greater than 12-14%. 13. The method for fabricating a flat glass according to claim U, wherein the hydrogen content in the protective atmosphere is 5% to 14% for the floating bath region located in the hot portion of the first half of the floating bath. between. Sweet twenty one