Manufacturing method of glass

Abstract

To provide a manufacturing method of a glass capable of manufacturing a glass with less bubble.SOLUTION: A manufacturing method of a glass includes a step of holding or flowing a molten glass in a state where the molten glass is contacted with a metal wall composed of platinum or a platinum alloy. The molten glass has a SO3 saturation solubility of 0.05 (wt%) or less. The manufacturing method further includes an adjustment step of adjusting at least either of a sulfur concentration CS, a steam partial pressure pH2O and an oxygen partial pressure pO2 such that a value SP calculated with an equation (1) satisfies SP≤3.10 where a sulfur concentration of the molten glass is CS (wt%), a stream partial pressure of an enclosure space of the metal wall is pH2O (atm), and an oxygen partial pressure of an enclosure space of the metal wall is pO2 (atm). SP=CS×pH2O / pO2 (1).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing glass, and more particularly to a method for manufacturing glass with few bubbles.

Background Art

[0002] In glass manufacturing, how to remove bubbles in molten glass or how not to generate them has become a major issue.

[0003] In particular, in the case of glass for pharmaceutical containers, if there are many bubbles, it becomes difficult to distinguish between bubbles in the container and foreign substances in the chemical solution during the appearance inspection after filling the chemical solution, and there is a risk that the inspection cannot be performed correctly. Therefore, the production of glass with few bubbles has become an important issue.

[0004] In addition, for glass plates used for substrates of liquid crystal displays or organic EL displays, as the size increases, the required level of bubble quality has been increasing year by year, and the solution of the above problems has become important.

[0005] The method of removing bubbles in molten glass is called fining. As the most common fining method, a fining agent such as a sulfate that generates gas at high temperature is added to the glass raw material, and gas is generated from the fining agent in the fining process to expand the bubbles and float them for defoaming.

[0006] In the manufacturing process of glass for the above applications, in order to avoid defects caused by the elution of refractories, melting may be performed in a metal container such as platinum. However, when a metal container such as platinum is used, the OH groups dissolved in the glass dissociate into hydrogen and oxygen, and hydrogen permeates through the platinum, resulting in O 2 It is known that bubbles are generated at the interface of the container.

[0007] Such O 2As a technique for suppressing bubbles, for example, Patent Document 1 discloses a method of estimating the hydrogen partial pressure in a metal container using an oxygen reference electrode composed of zirconia in a glass melt and measuring and controlling the relative hydrogen partial pressures inside and outside the metal container.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] However, in the conventional technologies such as Patent Document 1 mentioned above, the suppression of SO 2 bubbles has not been considered, and sufficient bubble suppression has not been achieved.

[0010] When using sulfate as a clarifying agent, SO 2 bubbles may occur as defects in the glass. There are various possible causes for such SO 2 bubbles. As one factor, the reverse permeation of hydrogen (permeation from the outside to the inside of the metal container) generated by the decomposition of H 2 O at the outer interface of the metal container reduces the molten glass, and the SO 3 saturation solubility of the molten glass decreases, which may cause SO 2 bubbles as so-called reboil bubbles. In particular, in the production of glasses with a low SO 3 saturation solubility composition system such as borosilicate glass for pharmaceutical containers and alkali-free glass for display substrates, the generation of such SO 2 bubbles is likely to be prominent. And such SO 2 bubbles were difficult to suppress only by controlling the hydrogen partial pressures inside and outside the platinum container.

[0011] In addition, an oxygen reference electrode composed of zirconia is easily eroded in a glass melt at high temperature and containing an alkali metal. When zirconia elutes into the molten glass, the SO 3 saturation solubility of the glass decreases, and there is a concern that SO 2 bubbles are likely to occur.

[0012] An object of the present invention is to provide a method for producing glass with few bubbles.

Means for Solving the Problems

[0013] A method for producing glass according to a first aspect of the present invention is a method for producing glass including a step of holding or flowing a molten glass in contact with a metal wall made of platinum or a platinum alloy, wherein the molten glass has an SO 3 saturation solubility of 0.05 (wt%) or less, and the sulfur concentration C S (wt%) of the molten glass, the water vapor partial pressure pH 2 O (atm) in the outer space of the metal wall, and the oxygen partial pressure pO 2 (atm) in the outer space of the metal wall, and the numerical value SP calculated by the formula (1) satisfies SP ≦ 3.10. The sulfur concentration C S , the water vapor partial pressure pH 2 O, and the oxygen partial pressure pO 2 are further adjusted in an adjustment step. SP = C S ×pH 2 O / pO 2 (1)

[0014] A method for producing glass according to a second aspect of the present invention is a method for producing glass according to any of the above aspects, wherein in the adjustment step, the sulfur concentration C S , the water vapor partial pressure pH 2 O, and the oxygen partial pressure pO 2 are adjusted so that 0.0013 ≦ SP.

[0015] A method for producing glass according to a third aspect of the present invention is a method for producing glass according to any of the above aspects, wherein in the adjustment step, the sulfur concentration C S, water vapor partial pressure pH 2 O, oxygen partial pressure pO 2 characterized by adjusting at least any one of them.

[0016] The method for producing glass according to the fourth aspect of the present invention is, in any of the above aspects, in the outer space of the metal wall, the oxygen partial pressure pO of the outer space 2 is provided with an oxygen partial pressure measuring means for measuring and an oxygen supply means for supplying oxygen to the outer space, and the supply amount of oxygen is adjusted based on the measured oxygen partial pressure pO 2 so that the oxygen partial pressure pO 2 is adjusted within the range of 0.0008 to 0.17 (atm).

[0017] The method for producing glass according to the fifth aspect of the present invention is, in any of the above aspects, in the outer space of the metal wall, the water vapor partial pressure pH in the outer space 2 O is provided with a water vapor partial pressure measuring means for measuring and a water vapor supply means for supplying water vapor to the outer space, and the supply amount of water vapor is adjusted based on the measured water vapor partial pressure pH 2 O so that the water vapor partial pressure pH 2 O is adjusted within the range of 0.07 to 0.37 (atm).

[0018] The method for producing glass according to the sixth aspect of the present invention further includes, in any of the above aspects, a step of preparing a glass raw material for obtaining molten glass, and adjusting the SO content in the glass raw material 3 so that the sulfur concentration C S is adjusted to 0.005 wt% or less.

[0019] The method for producing glass according to the seventh aspect of the present invention is, in any of the above aspects, characterized in that the viscosity of the molten glass in contact with the metal wall is 10 4.0 dPa·s or less.

[0020] The method for producing glass according to the eighth aspect of the present invention is, in any of the above aspects, the glass obtained by forming the molten glass has, as a glass composition, in mass%, SiO2 65 to 80%, B 2 O 3 characterized by containing 9.5 to 15%.

[0021] In the method for producing glass according to the ninth aspect of the present invention, in any of the above aspects, the glass obtained by shaping the molten glass has, as a glass composition, in mass%, SiO 2 50 to 70%, Al 2 O 3 12 to 25%, B 2 O 3 0 to 12%, Li 2 O + Na 2 O + K 2 O (total amount of Li 2 O, Na 2 O and K 2 O) less than 0 to 1%, MgO 0 to 8%, CaO 0 to 15%, SrO 0 to 12%, BaO 0 to 15%, characterized by containing.

Effects of the Invention

[0022] According to the present invention, glass with few bubbles can be produced.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0024] The glass manufacturing apparatus 1 and the method for manufacturing glass of the present invention will be described. FIG. 1 is an example of a glass manufacturing apparatus according to an embodiment of the present invention.

[0025] <Glass Manufacturing Apparatus> The glass manufacturing apparatus 1 includes a glass storage container 10, a surrounding container 20, and an adjustment device 30.

[0026] The glass-containing container 10 is a member that holds and / or allows the molten glass G to flow inside. At least a part or all of the inner surface of the glass-containing container 10 that comes into contact with the molten glass G is constituted by a metal wall of platinum or a platinum alloy. The platinum alloy is typically an alloy of platinum and one or more arbitrary metals selected from rhodium, iridium, osmium, rhenium, ruthenium, palladium, gold, and silver. In the present embodiment, the glass-containing container 10 is typically a platinum metal container and is a small glass melting pot. The glass-containing container 10 may be entirely constituted by platinum or platinum. The glass-containing container 10 is heated and / or kept warm by a heat source (not shown), and the molten glass G inside is maintained in a molten state. Also, the outer peripheral surface of the glass-containing container 10 may be supported by a structure such as a refractory. The concept of the glass-containing container 10 includes any member that holds and / or allows the molten glass G to flow inside in glass manufacturing, regardless of its shape and scale, such as a glass melting furnace with a metal-lined inner surface, a fining pipe, and a glass transport pipe.

[0027] A raw material supply pipe 11 and a glass delivery pipe 13 are connected to the glass-containing container 10. The raw material supply pipe 11 is a member that supplies the glass raw materials prepared and stored in the raw material preparation device 12 into the glass-containing container 10. The glass delivery pipe 13 is a member that delivers the molten glass G from inside the glass-containing container 10 to the outside. According to such a configuration, the molten glass G can be continuously produced.

[0028] In the case of batch production of the molten glass G, for example, a part (e.g., the upper part) of the glass-containing container 10 may be configured to be openable by a lid or the like that can be opened and closed, enabling the input and output of the glass raw materials and the molten glass G. When such a configuration is adopted, the raw material supply pipe 11 and the glass delivery pipe 13 may be omitted.

[0029] The surrounding container 20 is a member that surrounds the glass-containing container 10 at a distance. An outer surrounding space 21 is formed between the surrounding container 20 and the glass-containing container 10. In order to preferably control the atmosphere in the outer surrounding space 21, the surrounding container 20 preferably has high airtightness. The concept of the surrounding container 20 may include members that can surround the glass-containing container 10, regardless of their shape and scale, such as small refractory containers, furnace walls, and buildings composed of any building materials.

[0030] The adjustment device 30 is a device that adjusts the manufacturing conditions and atmosphere of the molten glass G. Specifically, the adjustment device 30 adjusts the sulfur concentration C S (wt%) of the molten glass G, the water vapor partial pressure pH 2 O (atm) of the outer surrounding space 21, and the oxygen partial pressure pO 2 (atm) of the outer surrounding space 21. The adjustment device 30 includes an oxygen partial pressure sensor 40, an oxygen supply device 41, a water vapor partial pressure sensor 50, a water vapor supply device 51, and a controller 60.

[0031] The oxygen partial pressure sensor 40 (oxygen partial pressure measuring means) is a device that measures the oxygen partial pressure of the outer surrounding space 21. As the oxygen partial pressure sensor 40, an oxygen sensor of a well-known method can be adopted. The oxygen partial pressure sensor 40 measures the oxygen partial pressure pO 2 of the outer surrounding space 21, and transmits the measured value of the oxygen partial pressure pO 2 to the controller 60.

[0032] The oxygen supply device 41 (oxygen supply means) is a device that supplies oxygen into the outer surrounding space 21. The oxygen supply device 41 includes, for example, a tank for storing oxygen, a pipe for transferring oxygen, and a damper for adjusting the oxygen supply amount. The oxygen supply device 41 is connected to the controller 60 and adjusts the oxygen supply amount according to an instruction signal from the controller 60.

[0033] The water vapor partial pressure sensor 50 (water vapor partial pressure measuring means) is a device that measures the water vapor partial pressure of the outer surrounding space 21. As the water vapor partial pressure sensor 50, a water vapor sensor of a well-known method can be adopted. The water vapor partial pressure sensor 50 measures the water vapor partial pressure pH 2Measure O, and transmit the measured water vapor partial pressure pH 2 The value of O to the controller 60.

[0034] The water vapor supply device 51 (water vapor supply means) is a device that supplies water vapor into the surrounding space 21. The water vapor supply device 51 includes, for example, a device that generates water vapor by heating or ultrasonic waves, and piping for transferring water vapor. The water vapor supply device 51 is connected to the controller 60 and adjusts the supply amount of water vapor according to an instruction signal from the controller 60.

[0035] The controller 60 controls the raw material preparation device 12, the oxygen supply device 41, and the water vapor supply device 51 to adjust the water vapor partial pressure pH 2 O, the oxygen partial pressure pO 2 , and the sulfur concentration C S (wt%) (adjustment process).

[0036] The controller 60 is typically a computer and includes an interface for receiving external inputs, an arithmetic device such as a CPU, and a storage device such as a memory and a storage. The controller 60 receives and stores the atmospheric information (pO 2 , pH 2 O) from the oxygen partial pressure sensor 40 and the water vapor partial pressure sensor 50. In addition, the controller 60 receives and stores the sulfur concentration C S from an input by an operator or an external device. Note that the sulfur concentration C S can be calculated in advance based on the glass raw material information, or measured by analyzing the molten glass G. The controller 60 calculates a numerical value SP based on the obtained sulfur concentration C S , the water vapor partial pressure pH 2 O, and the oxygen partial pressure pO 2 from the following formula (1). SP = C S × pH 2 O / pO 2 (1)

[0037] Furthermore, the controller 60 controls at least one of the raw material blending device 12, the oxygen supply device 41, and the steam supply device 51 so that the calculated SP value falls within a predetermined threshold range. Specifically, when the SP value is greater than the set upper limit value such that SP ≦ 3.10, the controller 60 reduces the amount of sulfate added to the raw material batch in the raw material blending device 12 to decrease the sulfur concentration C S by controlling to decrease it, decreases the steam supply amount from the steam supply device 51 to decrease the steam partial pressure pH 2 O, and increases the oxygen supply amount from the oxygen supply device 41 to increase the oxygen partial pressure pO 2 by controlling to increase it, and executes at least one of these controls.

[0038] According to such control, without directly measuring the hydrogen partial pressure or the like of the molten glass G, by adjusting the atmosphere in the surrounding space 21, the state of the molten glass G can be appropriately controlled, and the generation of SO 2 foam can be preferably suppressed. Note that the controller 60 may be composed of a single computer or may be composed of a plurality of computers.

[0039] Furthermore, it is preferable that the controller 60 controls at least one of the raw material blending device 12, the oxygen supply device 41, and the steam supply device 51 so that 0.0013 ≦ SP. That is, when the SP value is less than the set lower limit value, the amount of sulfate added to the raw material batch in the raw material blending device 12 is increased to increase the sulfur concentration C S by controlling to increase it, increases the steam supply amount from the steam supply device 51 to increase the steam partial pressure pH 2 O, and decreases the oxygen supply amount from the oxygen supply device 41 to decrease the oxygen partial pressure pO 2 by controlling to decrease it, and executes at least one of these controls.

[0040] The upper limit value of the SP value is more preferably 2.0 or less, 1.3 or less, 1.1 or less. If the SP value is too large, SO 2 foam is likely to occur. In other words, SO 2 foam is related to the sulfur concentration C SThe higher the value, the higher the water vapor partial pressure pH 2 O, or the lower the oxygen partial pressure pO 2 , the easier it is to occur.

[0041] The lower limit value of the SP value is more preferably 0.0040 or more, 0.0060 or more, 0.0080 or more, 0.0100 or more, 0.0130 or more. If the SP value is too small, O 2 Bubbles are likely to occur. In other words, O 2 Bubbles are more likely to occur as the water vapor partial pressure pH 2 O is lower, or the oxygen partial pressure pO 2 is higher.

[0042] The sulfur concentration C S The preferred range is 0.0001 - 0.0050 wt%, more preferably 0.0003 - 0.0020 wt%, 0.0005 - 0.0016 wt%. If the value of the sulfur concentration C S is too small, it is difficult to obtain a clarification effect. On the other hand, if the value of the sulfur concentration C S is too high, even if the water vapor partial pressure pH 2 O and the oxygen partial pressure pO 2 are controlled, it becomes difficult to control the suppression of SO 2 bubbles.

[0043] The preferred range of the water vapor partial pressure pH 2 O is 0.07 - 0.37 atm, more preferably 0.10 - 0.30 atm. Depending on the glass composition, the adjustable range of the sulfur concentration C S may not be large. In such a case, if the value of the water vapor partial pressure pH 2 O is too large, it becomes difficult to adjust the SP value to an appropriate value, and it becomes difficult to suppress SO 2 bubbles. Similarly, if the value of the water vapor partial pressure pH 2 O is too small, it becomes difficult to adjust the SP value to an appropriate value, and it becomes difficult to suppress O 2 bubbles.

[0044] The oxygen partial pressure pO 2The preferable range is 0.0008 to 0.17 atm, more preferably 0.0010 to 0.11 atm. Depending on the glass composition, the adjustable range of sulfur concentration C S may not be large. In such a case, if the value of oxygen partial pressure pO 2 is too small, it becomes difficult to adjust the SP value to an appropriate value, and it becomes difficult to suppress SO 2 bubbles. Similarly, if the value of water vapor partial pressure pH 2 O is too large, it becomes difficult to adjust the SP value to an appropriate value, and it becomes difficult to suppress O 2 bubbles.

[0045] <Method for manufacturing glass> Hereinafter, the method for manufacturing the glass of the present invention using the glass manufacturing apparatus 1 will be described.

[0046] First, a glass batch is prepared by formulating glass raw materials so as to obtain a desired glass composition. Although the present invention can be applied to the production of glass having an arbitrary composition, it is used for glass having a relatively low SO 3 saturation solubility, typically glass having an SO 3 saturation solubility of 0.05 (wt%) or less. Specifically, it is applicable to the production of glass having the following composition.

[0047] When manufacturing borosilicate glass for pharmaceutical containers, in terms of mass%, the glass composition contains SiO 2 60 to 80%, Al 2 O 3 3 to 10%, B 2 O 3 5 to 15%, MgO + CaO + BaO + SrO (total amount of MgO, CaO, BaO and SrO) 0 to 5%, Li 2 O + Na 2 O + K 2 O (total amount of Li 2 O, Na 2 O and K 2 O) is preferably 4 to 15%. It is preferable to formulate the glass raw materials so as to contain.

[0048] When manufacturing non-alkali glass for displays, as the glass composition, in terms of mass%, SiO2 50 to 70%, Al 2 O 3 12 to 25%, B 2 O 3 0 to 12%, MgO 0 to 8%, CaO 0 to 15%, SrO 0 to 12%, BaO 0 to 15%, Li 2 O + Na 2 O + K 2 O (Li 2 O, Na 2 O and K 2 O (total content of Li

[0049] The reasons for limiting the composition ranges of the respective components as described above will be described below. In the following description, unless otherwise specified, the % notation means mass%.

[0050] SiO 2 is one of the elements constituting the glass network. SiO 2 content is preferably 50 to 80%, 55 to 75%. SiO 2 content is too low, the chemical durability decreases. On the other hand, if the SiO 2 content is too high, the viscosity of the glass increases and the defoaming becomes poor.

[0051] Al 2 O 3 is a component that suppresses devitrification of the glass and also improves chemical durability and hydrolysis resistance. Al 2 O 3 content is preferably 4 to 25%, 5 to 20%, particularly 6 to 18%. Al 2 O 3 content is too low, the above effects cannot be obtained. On the other hand, if the Al 2 O 3 content is too high, the viscosity of the glass increases and the defoaming becomes poor.

[0052] B 2 O 3It not only reduces the melting point of the glass, but also increases the liquid-phase viscosity and has the effect of suppressing devitrification. B 2 O 3 The content of is 5 to 15%, preferably 9 to 13%, particularly preferably 10 to 12%. B 2 O 3 If the content of is too low, the viscosity of the glass increases and the defoaming property deteriorates. On the other hand, B 2 O 3 If the content of is too high, the hydrolysis resistance and chemical durability decrease.

[0053] MgO, CaO, BaO and SrO are alkaline earth metal oxides and have the effect of reducing the viscosity of the glass. They also affect the alkali elution amount. If the content of the alkaline earth metal oxides is too high, the alkali elution amount from the glass increases, and the thermal expansion coefficient increases, resulting in a decrease in thermal shock resistance. If the content of the alkaline earth metal oxides is too low, it becomes difficult to achieve an operating point of 1200 °C or lower. Therefore, for the use of borosilicate glass for pharmaceutical containers, MgO + CaO + BaO + SrO (the total amount of MgO, CaO, BaO and SrO) is preferably 0 to 5%, 0.1 to 4%, 0.3 to 3%, 0.5 to 2%, particularly preferably 0.9 to 1.8%.

[0054] MgO has the effect of improving chemical durability. The content of MgO is preferably 0 to 4%, 0 to 2%, particularly preferably 0 to 1%. If the content of MgO is too high, the hydrolysis resistance deteriorates.

[0055] CaO has the effect of reducing the high-temperature viscosity of the glass. The content of CaO is preferably 0 to 10%, 0.1 to 9%, particularly preferably 0.2 to 8.5%. If the content of CaO is too high, the hydrolysis resistance deteriorates.

[0056] SrO has the effect of improving chemical durability. The content of SrO is preferably 0 to 4%, 0 to 2%, particularly preferably 0 to 1%. If the content of SrO is too high, the hydrolysis resistance deteriorates.

[0057] BaO has the effect of reducing the high-temperature viscosity of the glass. The content of BaO is preferably 0 to 10%, 0 to 6%, 0.1 to 3%, particularly 0.5 to 2%. If the content of BaO is too high, the hydrolysis resistance deteriorates.

[0058] Li 2 O, Na 2 O and K 2 O is an alkali metal oxide and has the effect of reducing the viscosity of the glass. However, when the total amount of these components increases, the alkali elution amount from the glass increases, and further, the thermal expansion coefficient increases and the thermal shock resistance decreases. If the content of the alkali metal oxide is too low, it becomes difficult to achieve an operating point below 1200 °C. Therefore, in the case of borosilicate glass for pharmaceutical containers, Li 2 O + Na 2 O + K 2 O (total amount of Li 2 O, Na 2 O and K 2 O) is preferably 4 to 15%, 3 to 12%, 4 to 10%, 5 to 9%, 6 to 8%, particularly 7 to 8%. Also, in the case of non-alkali glass for displays, Li 2 O + Na 2 O + K 2 O (total amount of Li 2 O, Na 2 O and K 2 O) is preferably less than 0 to 1%.

[0059] Na 2 O has the effect of reducing the viscosity of the glass and increasing the linear thermal expansion coefficient. Na 2 O is preferably not actively added to non-alkali glass, but addition is allowed in borosilicate glass for pharmaceutical containers. When adding Na 2 O, its content is preferably 3 to 10%, 4 to 9%, particularly 5 to 8%. If the content of Na 2 O is too low, the viscosity of the glass increases and the defoaming property deteriorates. On the other hand, if the content of Na 2 O is too high, the hydrolysis resistance deteriorates.

[0060] K 2O is Na 2 O has the effect of reducing the viscosity of the glass and increasing the linear thermal expansion coefficient, similar to that of K 2 O is preferably not actively added to the non-alkali glass, but its addition is allowed in the borosilicate glass for pharmaceutical containers. K 2 When adding K 2 O, its content is preferably 0 - 6%, 0 - 4%, 0 - 3%, especially 0.5 - 2.5%. K 2 If the content of K 2 O is too much, the hydrolysis resistance deteriorates. In addition, K

[0061] Li 2 O is similar to Na 2 O and K 2 O in that it has the effect of reducing the viscosity of the glass and increasing the linear thermal expansion coefficient. However, when adding Li 2 O, the refractory is easily eroded during glass melting. Also, it leads to an increase in production costs. Therefore, the content of Li 2 O is preferably 0 - 1%, 0 - 0.5%, especially 0 - 0.1%. Without special circumstances, it is preferable to use other alkali oxides other than Li 2 O.

[0062] Furthermore, it is preferable to add sulfates to the glass raw materials formulated to have the above glass composition within the range where the above SP value is satisfied.

[0063] Next, this glass batch is put into the above-mentioned glass manufacturing apparatus 1 and melted to obtain molten glass. According to the above-mentioned glass manufacturing apparatus 1, based on the SP value, the sulfur concentration C S , the water vapor partial pressure pH 2 O, and the oxygen partial pressure pO 2 are preferably adjusted. That is, while adjusting to SP ≤ 3.10, it is possible to manufacture glass with fewer SO 2 bubbles.

[0064] Incidentally, the method for manufacturing glass according to the present invention can also be implemented in such a manner that an operator manually performs the processing of the adjustment step performed by the controller 60 in the above-described glass manufacturing apparatus 1. That is, the operator calculates the sulfur concentration C S based on the raw material information, measures the atmosphere information (pO 2 , pH 2 O) using the oxygen partial pressure sensor 40 and the water vapor partial pressure sensor 50, and can calculate the SP value. Further, the operator can control at least any one of the raw material blending device 12, the oxygen supply device 41, and the water vapor supply device 51 based on the calculated SP value. Also, it is possible to adopt a mode in which the operator is responsible for only a part of the adjustment process of the controller 60.

[0065] The method for manufacturing glass according to the present invention preferably further includes a forming step of forming the molten glass G to obtain a glass article. The molten glass G can be formed into an arbitrary shape using an arbitrary forming method. For example, the glass for pharmaceutical containers can be formed into a tubular shape using the Danner method, the Vello method, the down-draw method, or the like. Also, the glass for displays can be formed into a plate shape using the overflow down-draw method, the slot down-draw method, the float method, the roll-out method, or the like.

[0066] The number of bubbles in the obtained glass article is preferably 25,000 bubbles / ton or less, 20,000 bubbles / ton or less, particularly 18,000 bubbles / ton or less.

Examples

[0067] Hereinafter, the present invention will be described based on examples. In this example, the results of simulating the method for manufacturing glass according to the present invention using the experimental apparatus J shown in FIG. 2 are shown. Tables 1 to 6 show the examples (No. 1 to 20, 22 to 26, 29 to 40) and comparative examples (No. 21, 27, 28) of the present invention.

[0068] The experimental apparatus J shown in Fig. 2 includes a quartz container Q, an electric furnace E, and a metal tube T. The quartz container Q is a container-shaped member made of quartz, having visible light transmissibility and heat resistance, and capable of holding molten glass G inside. The electric furnace E is a device that houses and heats the quartz container Q inside. The electric furnace E is provided with an observation window through which the inside can be observed with a camera. The metal tube T is a platinum U-shaped tubular member composed of a metal wall with an outer diameter of 6 mm and a thickness of 0.8 mm. The bent portion of the metal tube T is immersed in the molten glass G inside the quartz container Q. Inside the metal tube T, a mixed gas of the components and partial pressures described in each table can be introduced from a gas inlet (Tin) with one opening to an outlet (Tout) with the other opening. That is, the metal tube T is a platinum member that contacts the molten glass G, and is a model of the glass storage container 10 in the above-described glass manufacturing apparatus 1. Also, the inside of the metal tube T is a model of the surrounding space 21.

[0069] First, glass raw materials were formulated and mixed to obtain base glass batches of glass compositions a and b so as to have the following compositions. Glass composition a is a borosilicate glass containing 73% SiO₂, 7% Al₂O₃, 10% B₂O₃, 1% CaO, 1% BaO, 6% Na₂O, and 2% K₂O by mass as the glass composition. Glass composition b is a non-alkali glass containing 59.2% SiO₂, 19.3% Al₂O₃, 6.5% B₂O₃, 2.5% MgO, 6.3% CaO, 0.5% SrO, and 5.7% BaO by mass as the glass composition. Further, for the above base glass batches, sulfate raw materials were externally added and adjusted as necessary so as to have the sulfur concentration C shown in each table, and the glass batches of each example were adjusted. 2 73%, Al 2 O 3 7%, B 2 O 3 10%, CaO 1%, BaO 1%, Na 2 O 6%, K 2 O 2% is a borosilicate glass containing. Glass composition b is a non-alkali glass containing 59.2% SiO 2 59.2%, Al 2 O 3 19.3%, B 2 O 3 6.5%, MgO 2.5%, CaO 6.3%, SrO 0.5%, BaO 5.7% contains. Further, for the above base glass batches, the sulfate raw material is externally added and adjusted as necessary so that the sulfur concentration C shown in each table is obtained, and the glass batch of each example is adjusted. S and the glass batches of each example were adjusted.

[0070] After the obtained glass batch was put into the quartz container Q, the quartz container Q was placed in the electric furnace E and heated for 10 minutes until a predetermined viscosity η was reached to obtain the molten glass G. Specifically, in the example of the glass composition a, it was heated so that the viscosity η became 720 dPa·s. In the example of the glass composition b, it was heated so that the viscosity η became 890 dPa·s.

[0071] Incidentally, the saturation solubility of SO in the glass of the glass composition a at 720 dPa·s is 0.009% by mass. The saturation solubility of SO in the glass of the glass composition b at 890 dPa·s is 0.005% by mass. 3 Incidentally, the saturation solubility of SO in the glass of the glass composition a at 720 dPa·s is 0.009% by mass. The saturation solubility of SO in the glass of the glass composition b at 890 dPa·s is 0.005% by mass. 3 is 0.005% by mass.

[0072] Next, gas was supplied at 0.5 L / min from the gas inlet (Tin) of the metal tube T so that the pH shown in each table was reached, and the treatment of discharging from the discharge port (Tout) was continued for 45 minutes. Then, an observation image of the interface where the metal tube T contacts the molten glass G was taken with a CCD camera (not shown) through the quartz container Q from the observation window of the electric furnace E. 2 O, pO 2 , pN 2 was reached, and the treatment of discharging from the discharge port (Tout) was continued for 45 minutes. Then, an observation image of the interface where the metal tube T contacts the molten glass G was taken with a CCD camera (not shown) through the quartz container Q from the observation window of the electric furnace E.

[0073] From the observation images of each example obtained in this way, when foaming or an increase in bubble diameter was not observed at the interface between the molten glass G and the metal tube T, it was designated as "A". When the shrinkage of the bubble diameter was slow or the increase in the bubble diameter was slight and no floating was observed at the interface between the molten glass G and the metal tube T, it was designated as "B". When bubbles were observed floating or detaching at the interface between the molten glass G and the metal tube T, it was designated as "C", and the foaming state was determined.

[0074] Furthermore, for the examples and comparative examples in which foaming was recognized, the molten glass G was cooled to obtain a glass sample containing bubbles, and the main component of the gas in the bubbles was analyzed from the sample using a laser Raman spectrophotometer.

[0075]

Table 1

[0076] [Table 2]

[0077] [Table 3]

[0078] [Table 4]

[0079] [Table 5]

[0080] [Table 6]

[0081] As is clear from Tables 1 to 6, in Examples No. 21, 27, and 28, since the SP value was excessive, SO 2 foaming of bubbles was observed. On the other hand, in other examples, as a result of suppressing the SP value, SO 2 there was little foaming of bubbles or no foaming was observed.

Industrial Applicability

[0082] The method for producing glass of the present invention is useful as a material for pharmaceutical containers such as vials, ampoules, and the like, and syringes of syringes.

Explanation of Symbols

[0083] 1 Glass manufacturing apparatus 10 Glass storage container 11 Raw material supply pipe 12 Raw material blending device 13 Glass delivery pipe 20 Surrounding container 21 Outer surrounding space 30 Adjusting device 40 Oxygen partial pressure sensor (oxygen partial pressure measuring means) 41 Oxygen supply device (oxygen supply means) 50 Water vapor partial pressure sensor (water vapor partial pressure measurement means) 51 Water vapor supply device (water vapor supply means) 60 Controller J Experimental device Q Quartz container E Electric furnace T Metal tube G Molten glass

Claims

1. 1. A method for producing glass, comprising: holding or flowing molten glass in contact with a metal wall made of platinum or a platinum alloy, The molten glass is SO ３ with a saturation solubility of 0.05 (wt%) or less, The sulfur concentration C of the molten glass Ｓ (wt%), the water vapor partial pressure pH ２ O (atm) of the outer space of the metal wall, and the oxygen partial pressure pO ２ (atm) of the outer space of the metal wall, the numerical value SP calculated by the formula (1) satisfies SP ≦ 3.10, the sulfur concentration C Ｓ , the water vapor partial pressure pH ２ O, and the oxygen partial pressure pO ２ A method for producing glass, further comprising an adjustment step of adjusting at least any one of them. SP=C Ｓ ×pH ２ O / pO ２ (1)

2. In the adjusting step, the sulfur concentration C is adjusted so as to satisfy 0.0013≦SP. Ｓ , the water vapor partial pressure pH ２ O, the oxygen partial pressure pO ２ The method for producing glass according to claim 1 , further comprising adjusting at least one of the following:

3. In the adjustment step, the sulfur concentration C is adjusted so as to satisfy 0.0040≦SP≦1.

30. Ｓ , the water vapor partial pressure pH ２ O, the oxygen partial pressure pO ２ The method for producing glass according to claim 1 or 2, further comprising adjusting at least one of the following:

4. The metal wall is provided in an enclosed space. The oxygen partial pressure pO in the surrounding space ２ An oxygen partial pressure measuring means for measuring the oxygen partial pressure; an oxygen supply means for supplying oxygen to the surrounding space; The measured oxygen partial pressure pO ２ The oxygen partial pressure pO ２ The method for producing glass according to claim 1 or 2, wherein the concentration of the glass is adjusted to within a range of 0.0008 to 0.17 (atm).

5. The metal wall is provided in an enclosed space. The water vapor partial pressure pH in the surrounding space ２ A water vapor partial pressure measuring means for measuring O; a water vapor supply means for supplying water vapor to the surrounding space; The measured water vapor partial pressure pH ２ The water vapor partial pressure pH ２ 3. The method for producing glass according to claim 1, wherein O is adjusted to fall within the range of 0.07 to 0.37 (atm).

6. The step of preparing a glass frit for obtaining the molten glass further comprises the step of: ３ By adjusting the content, the sulfur concentration C Ｓ The method for producing glass according to claim 1 or 2, wherein the content of is adjusted to 0.005 wt % or less.

7. The viscosity of the molten glass in contact with the metal wall is 10 ４．０ The method for producing glass according to claim 1 or 2, wherein the viscosity of the glass is dPa·s or less.

8. The glass obtained by forming the molten glass has a glass composition, in mass %, of SiO ２ 65-80%, B ２ O ３ The method for producing glass according to claim 1 or 2, wherein the content is 9.5 to 15%.

9. The glass obtained by forming the molten glass has a glass composition, in mass %, of SiO ２ 50-70%, Al ２ O ３ 12-25%, B ２ O ３ 0-12%, Li ２ O+Na ２ O+K ２ O (Li ２ O, Na ２ O and K ２ 3. The method for producing glass according to claim 1 or 2, comprising the steps of: (a total amount of ZnO and O) 0 to less than 1%, MgO 0 to 8%, CaO 0 to 15%, SrO 0 to 12%, and BaO 0 to 15%.

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