Method for producing glass

Abstract

The present invention is a method for producing glass, which comprises a step for holding or flowing molten glass while in contact with a metal wall comprising platinum or a platinum alloy, the method being characterized in that the molten glass has an SO3 saturation solubility of 0.05 (wt%) or less, and in that the method also has an adjustment step for adjusting at least one of the sulfur concentration CS, the water vapor partial pressure pH2O and the oxygen partial pressure pO2, where the sulfur concentration in the molten glass is denoted by CS (wt%), the water vapor partial pressure in an outer space of the metal wall is denoted by pH2O (atm), and the oxygen partial pressure in the outer space of the metal wall is denoted by pO2 (atm), so that the SP value calculated from formula (1) is such that SP≤3.10.　Formula (1): SP = CS × pH2O / pO2.

Description

Glass manufacturing method

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

[0002] In glass production, how to remove bubbles in molten glass or how to prevent bubbles from being generated is a major issue.

[0003] In particular, in glass for pharmaceutical containers, if there are many bubbles, it becomes difficult to distinguish between bubbles in the container and foreign matter in the liquid medicine during visual inspection after filling the container with the liquid medicine, and there is a risk that the inspection will not be performed correctly, so producing glass with few bubbles is an important issue.

[0004] Furthermore, as glass plates used as substrates for liquid crystal displays or organic EL displays become larger, the required level of bubble prevention is increasing year by year, making it important to solve the above problem.

[0005] The technique of removing bubbles from molten glass is called fining. The most common fining method involves adding a fining agent, such as sulfate, which generates gas at high temperatures to the glass raw materials, and then generating gas from the fining agent during the fining process, causing the bubbles to expand and float up to the surface for degassing.

[0006] In the manufacturing process of glass for the above-mentioned applications, it is sometimes melted in a metal container such as platinum to avoid defects due to elution of refractories. However, when a metal container such as platinum is used, OH groups dissolved in the glass dissociate into hydrogen and oxygen, and the hydrogen permeates the platinum, generating O at the interface of the container. ２ Foaming is known to occur.

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

[0008] Special Publication No. 2001-503008

[0009] However, in the conventional techniques such as the above-mentioned Patent Document 1,２ No consideration was given to suppressing foam, and foam was not sufficiently suppressed.

[0010] When sulfate is used as a fining agent, SO 4 is formed as defects in the glass. ２ Bubbles may form. ２ There are various possible causes for the generation of bubbles. One of the causes is the formation of H ２ The molten glass is reduced by reverse permeation (permeation from the outside to the inside of the metal container) of hydrogen generated by the decomposition of O, and the SO ３ The decrease in saturated solubility allows SO to be released as so-called reboil bubbles. ２ In particular, the SO 2 content of borosilicate glass for pharmaceutical containers and alkali-free glass for display substrates is low. ３ In the production of glass with a composition in which the saturated solubility of SO is low, ２ The generation of bubbles tends to become significant. ２ It was difficult to suppress bubbles by simply controlling the hydrogen partial pressure inside and outside the platinum vessel.

[0011] Furthermore, an oxygen reference electrode made of zirconia is easily corroded in a high-temperature molten glass containing alkali metals. When zirconia dissolves in the molten glass, the SO ３ The saturated solubility decreases, and SO ２ There was concern that foaming would occur more easily.

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

[0013] A method for producing glass according to a first aspect of the present invention is a method for producing glass comprising a step of holding or flowing molten glass in contact with a metal wall made of platinum or a platinum alloy, wherein the molten glass is a mixture of SO ３ The saturated solubility is 0.05 (wt%) or less, and the sulfur concentration C of the molten glass Ｓ (wt%), water vapor partial pressure pH in the enclosed space of the metal wall ２ O (atm), and the oxygen partial pressure pO in the enclosed space of the metal wall ２(atm), the value SP calculated by the formula (1) is SP≦3.10, so that the sulfur concentration C Ｓ , water vapor partial pressure pH ２ O, and oxygen partial pressure pO ２ The present invention is characterized in that it further comprises an adjusting step of adjusting at least one of SP=C. Ｓ ×pH ２ O / pO ２ (1)

[0014] In the method for producing glass according to a second aspect of the present invention, in any one of the above aspects, the sulfur concentration C is adjusted so as to satisfy 0.0013≦SP in the adjusting step. Ｓ , water vapor partial pressure pH ２ O, partial pressure of oxygen pO ２ At least one of the above is adjusted.

[0015] The method for producing glass according to a third aspect of the present invention is any of the above aspects, further comprising adjusting the sulfur concentration C so that 0.0040≦SP≦1.30 in the adjusting step. Ｓ , water vapor partial pressure pH ２ O, partial pressure of oxygen pO ２ At least one of the above is adjusted.

[0016] A fourth aspect of the present invention relates to a method for producing glass, comprising the steps of: providing a glass having a metal wall and an oxygen partial pressure pO ２ and an oxygen supply means for supplying oxygen to the surrounding space, and the measured oxygen partial pressure pO ２ By adjusting the oxygen supply amount based on ２ is adjusted to within the range of 0.0008 to 0.17 (atm).

[0017] A fifth aspect of the present invention relates to a method for producing glass, comprising the steps of: providing a metal wall surrounding a space where a water vapor partial pressure pH ２ and a water vapor supply means for supplying water vapor to the surrounding space, and the measured water vapor partial pressure pH ２ By adjusting the amount of water vapor supplied based on the water vapor partial pressure pH ２The O concentration is adjusted to within the range of 0.07 to 0.37 (atm).

[0018] A method for producing glass according to a sixth aspect of the present invention is any one of the above aspects, further comprising a step of preparing glass raw materials for obtaining molten glass, and ３ By adjusting the content, the sulfur concentration C Ｓ is adjusted to 0.005 wt% or less.

[0019] A seventh aspect of the present invention relates to a method for producing glass, in any of the above-mentioned aspects, wherein the viscosity of the molten glass in contact with the metal wall is 10 ４．０ It is characterized by having a viscosity of dPa·s or less.

[0020] A method for producing glass according to an eighth aspect of the present invention is any one of the above-mentioned aspects, wherein the glass obtained by forming the molten glass contains, as a glass composition, in mass %, SiO ２ 65-80%, B ２ O ３ It is characterized by containing 9.5 to 15%.

[0021] A ninth aspect of the present invention relates to a method for producing glass, in any one of the above-mentioned aspects, wherein the glass obtained by forming the molten glass contains, as a glass composition, in mass %, 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 The glass is characterized by containing 0 to less than 1% of total amount of magnesium oxide, 0 to 8% of magnesium oxide, 0 to 15% of calcium oxide, 0 to 12% of strontium oxide, and 0 to 15% of bamboo.

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

[0023] Schematic diagram of a glass manufacturing apparatus according to an embodiment of the present invention. Schematic diagram of an experimental apparatus according to an example of the present invention.

[0024] A glass manufacturing apparatus 1 and a method for manufacturing glass according to the present invention will now be described. Fig. 1 shows 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 container 10 , an enclosing container 20 , and an adjusting device 30 .

[0026] The glass holding container 10 is a component that holds and / or flows molten glass G therein. At least a part or all of the inner surface of the glass holding container 10, which comes into contact with the molten glass G, is composed of a metal wall made of platinum or a platinum alloy. The platinum alloy is typically an alloy of platinum and one or more metals selected from rhodium, iridium, osmium, rhenium, ruthenium, palladium, gold, and silver. In this embodiment, the glass holding container 10 is typically a platinum metal container and a small glass melting pot. The glass holding container 10 may be entirely made of platinum or platinum. The glass holding container 10 is heated and / or kept warm by a heat source (not shown), and the molten glass G therein is maintained in a molten state. In addition, the outer peripheral surface of the glass holding container 10 may be supported by a structure such as a refractory material. The concept of the glass storage container 10 can include any component that holds and / or flows molten glass G inside during glass production, regardless of its shape or size, such as a glass melting furnace with a metal-lined inner surface, a refining pipe, or a glass transport pipe.

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

[0028] In the case of batch production of molten glass G, for example, a part (for example, an upper part) of the glass storage container 10 may be configured to be openable with an openable lid or the like, thereby enabling the introduction and delivery of glass raw materials and 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 vessel 20 is a member that surrounds the periphery of the glass-containing vessel 10 at a distance. An enclosed space 21 is formed between the surrounding vessel 20 and the glass-containing vessel 10. In order to suitably control the atmosphere in the enclosed space 21, the surrounding vessel 20 preferably has high airtightness. The concept of the surrounding vessel 20 may include any member capable of surrounding the glass-containing vessel 10, regardless of its shape or size, such as a small refractory vessel, a furnace wall, or a building made of any building material.

[0030] The adjusting device 30 is a device for adjusting the manufacturing conditions and atmosphere of the molten glass G. Specifically, the adjusting device 30 adjusts the sulfur concentration C Ｓ (wt%), the water vapor partial pressure pH of the enclosed space 21 ２ O (atm), and the oxygen partial pressure pO ２ The adjusting 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 for measuring the oxygen partial pressure in the enclosed space 21. A known type of oxygen sensor can be used as the oxygen partial pressure sensor 40. The oxygen partial pressure sensor 40 measures the oxygen partial pressure pO ２ Measure the measured oxygen partial pressure pO ２ The value of is transmitted to the controller 60.

[0032] The oxygen supply device 41 (oxygen supply means) is a device that supplies oxygen into the enclosed space 21. The oxygen supply device 41 includes, for example, a tank for storing oxygen, a pipe for transporting oxygen, and a damper for adjusting the amount of oxygen supplied. The oxygen supply device 41 is connected to the controller 60, and adjusts the amount of oxygen supplied in response 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 for measuring the water vapor partial pressure in the enclosed space 21. A well-known water vapor sensor can be used as the water vapor partial pressure sensor 50. The water vapor partial pressure sensor 50 measures the water vapor partial pressure pH of the enclosed space 21. ２ O was measured, and the water vapor partial pressure pH was measured.２ The value of O is sent to the controller 60.

[0034] The water vapor supply device 51 (water vapor supply means) is a device that supplies water vapor into the enclosed space 21. The water vapor supply device 51 includes, for example, a device that generates water vapor by heating or ultrasonic waves, a pipe for transporting water vapor, etc. The water vapor supply device 51 is connected to the controller 60, and adjusts the amount of water vapor supplied in response to an instruction signal from the controller 60.

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

[0036] The controller 60 is typically a computer, and includes an interface for receiving external input, a calculation device such as a CPU, and a storage device such as a memory. The controller 60 receives atmospheric information (pO ２ , pH ２ The controller 60 also receives and stores the sulfur concentration C Ｓ The sulfur concentration C Ｓ can be calculated in advance based on glass raw material information or can be measured by analyzing the molten glass G. The controller 60 calculates the sulfur concentration C Ｓ , water vapor partial pressure pH ２ O, and oxygen partial pressure pO ２ Then, the value SP is calculated based on 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 apparatus 12, the oxygen supplying apparatus 41, and the steam supplying apparatus 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, the controller 60 reduces the amount of sulfate added to the raw material batch in the raw material blending apparatus 12 to reduce the sulfur concentration C Ｓ The amount of water vapor supplied from the water vapor supply device 51 is reduced to reduce the water vapor partial pressure pH ２ O2 is reduced, and the amount of oxygen supplied from the oxygen supply device 41 is increased to reduce the oxygen partial pressure pO2. ２ and (3) control to increase the

[0038] According to such control, the state of the molten glass G can be appropriately controlled by adjusting the atmosphere in the surrounding space 21 without directly measuring the hydrogen partial pressure of the molten glass G, and the SO ２ The generation of bubbles can be suitably suppressed. The controller 60 may be configured by a single computer or by multiple computers.

[0039] Furthermore, it is preferable that the controller 60 controls at least one of the raw material blending apparatus 12, the oxygen supplying apparatus 41, and the steam supplying apparatus 51 so that the SP value satisfies the condition of 0.0013≦SP. That is, when the SP value is lower than the set lower limit, the amount of sulfate added to the raw material batch in the raw material blending apparatus 12 is increased to reduce the sulfur concentration C Ｓ , and increasing the amount of water vapor supplied from the water vapor supply device 50 to increase the water vapor partial pressure pH ２ O2 is increased, and the amount of oxygen supplied from the oxygen supply device 41 is reduced to increase the oxygen partial pressure pO2. ２ and (3) performing control to reduce the

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

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

[0042] Sulfur concentration C Ｓ The preferred range of sulfur concentration C is 0.0001 to 0.0050 wt%, more preferably 0.0003 to 0.0020 wt%, or 0.0005 to 0.0016 wt%. Ｓ If the value of is too small, it is difficult to obtain a fining effect. Ｓ If the value of is too high, the water vapor partial pressure pH ２ O and oxygen partial pressure pO ２ Even if you control SO ２ It becomes difficult to suppress and control foam.

[0043] Water vapor partial pressure pH ２ The preferred range of O is 0.07 to 0.37 atm, more preferably 0.10 to 0.30 atm. Depending on the glass composition, the sulfur concentration C Ｓ In some cases, the adjustable range of the water vapor partial pressure pH ２ If the value of O is too large, it becomes difficult to adjust the SP value to an appropriate value, and ２ Similarly, the water vapor partial pressure pH ２ If the value of O is too small, it becomes difficult to adjust the SP value to an appropriate value. ２ It becomes difficult to suppress foam.

[0044] Oxygen partial pressure pO ２ The preferred range of sulfur concentration C is 0.0008 to 0.17 atm, more preferably 0.0010 to 0.11 atm. Ｓ In some cases, the adjustable range of the oxygen partial pressure pO２ If the value is too small, it becomes difficult to adjust the SP value to an appropriate value, and ２ Similarly, the water vapor partial pressure pH ２ If the value of O is too large, it becomes difficult to adjust the SP value to an appropriate value. ２ It becomes difficult to suppress foam.

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

[0046] First, glass raw materials are mixed to prepare a glass batch having a desired glass composition. ３ Glasses with relatively low saturated solubility, typically SO ３ It is used for glasses with a saturated solubility of 0.05 (wt%) or less. Specifically, it can be applied to the production of glasses with the following compositions.

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

[0048] When producing alkali-free glass for displays, the glass composition contains, in mass %, SiO ２ 50-70%, Al ２ O ３ 12-25%, B ２ O ３ 0-12%, MgO 0-8%, CaO 0-15%, SrO 0-12%, BaO 0-15%, Li ２ O + Na ２O+K ２ O(Li ２ O, Na ２ O and K ２ It is preferable that the composition contains 0 to less than 1% of alkali metal oxide components (total amount of O). It is more preferable that the composition does not substantially contain alkali metal oxide components.

[0049] The reasons for limiting the composition range of each component as described above will be explained below. In the following explanation, unless otherwise specified, % means % by mass.

[0050] SiO ２ is one of the elements that make up the glass network. ２ The content of SiO is preferably 50 to 80%, more preferably 55 to 75%. ２ If the content is too low, the chemical durability will decrease. ２ If the content is too high, the viscosity of the glass increases and foam removal becomes poor.

[0051] Al ２ O ３ is a component that suppresses devitrification of the glass and improves chemical durability and hydrolysis resistance. ２ O ３ The content of Al is preferably 4 to 25%, 5 to 20%, and particularly preferably 6 to 18%. ２ O ３ If the content of Al is too small, the above effect cannot be obtained. ２ O ３ If the content is too high, the viscosity of the glass increases and foam removal becomes poor.

[0052] B ２ O ３ Not only does B lower the melting point of the glass, but it also increases the liquidus viscosity and suppresses devitrification. ２ O ３ The content of is 5 to 15%, preferably 9 to 13%, and particularly preferably 10 to 12%. ２ O ３ If the content of B is too low, the viscosity of the glass increases and bubbles do not disappear easily. ２ O ３ If the content is too high, the hydrolysis resistance and chemical durability will decrease.

[0053] MgO, CaO, BaO, and SrO are alkaline earth metal oxides that have the effect of reducing the viscosity of the glass. They also affect the amount of alkali elution. If the alkaline earth metal oxide content is too high, the amount of alkali elution from the glass increases, and the thermal expansion coefficient increases, reducing thermal shock resistance. If the alkaline earth metal oxide content is too low, it becomes difficult to achieve a working point of 1200°C or less. Therefore, in borosilicate glass for pharmaceutical containers, the content of 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%, or particularly 0.9 to 1.8%.

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

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

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

[0057] BaO has the effect of reducing the high-temperature viscosity of the glass. The BaO content is preferably 0 to 10%, 0 to 6%, 0.1 to 3%, and particularly preferably 0.5 to 2%. If the BaO content 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, if the total amount of these components is large, the amount of alkali elution from the glass increases, and further, the thermal expansion coefficient increases, reducing the thermal shock resistance. If the content of alkali metal oxides is too small, it becomes difficult to achieve a working point of 1200°C or less. Therefore, in the use of borosilicate glass for pharmaceutical containers, Li２ O + Na ２ O+K ２ O(Li ２ O, Na ２ O and K ２ The total amount of Li, O, etc. is preferably 4 to 15%, 3 to 12%, 4 to 10%, 5 to 9%, 6 to 8%, and particularly preferably 7 to 8%. ２ O + Na ２ O+K ２ O(Li ２ O, Na ２ O and K ２ The total amount of O is preferably 0 to less than 1%.

[0059] Na ２ O has the effect of decreasing the viscosity of the glass and increasing the linear thermal expansion coefficient. ２ It is preferable not to actively add O to alkali-free glass, but its addition is permitted in borosilicate glass for pharmaceutical containers. ２ When O is added, the content is preferably 3 to 10%, 4 to 9%, and particularly preferably 5 to 8%. ２ If the O content is too low, the viscosity of the glass increases and bubbles do not disappear easily. ２ If the O content is too high, the hydrolysis resistance deteriorates.

[0060] K ２ O is Na ２ Like O, it has the effect of lowering the viscosity of the glass and increasing the linear thermal expansion coefficient. ２ It is preferable not to actively add O to alkali-free glass, but its addition is permitted in borosilicate glass for pharmaceutical containers. ２ When O is added, its content is preferably 0 to 6%, 0 to 4%, 0 to 3%, and particularly preferably 0.5 to 2.5%. ２ If the O content is too high, the hydrolysis resistance will be deteriorated. ２ O and Na ２ The combined use of both components O is preferred because the mixed alkali effect improves hydrolysis resistance.

[0061] Li ２ O is Na ２O and K ２ Like O, it has the effect of lowering the viscosity of the glass and increasing the linear thermal expansion coefficient. ２ Addition of O makes it easier for refractories to corrode during glass melting, and also leads to increased production costs. ２ The content of O is preferably 0 to 1%, 0 to 0.5%, and particularly preferably 0 to 0.1%. ２ It is preferable to use alkali oxides other than O.

[0062] Furthermore, it is preferable to add sulfate to the glass raw materials prepared to obtain the above glass composition in a range in which the above-mentioned SP value is satisfied.

[0063] Next, this glass batch is introduced into the above-described glass manufacturing apparatus 1 and melted to obtain molten glass. Ｓ , the water vapor partial pressure pH ２ O, and the oxygen partial pressure pO ２ is suitably adjusted. That is, while adjusting so that SP≦3.10, ２ It is possible to produce glass with few bubbles.

[0064] The glass manufacturing method of the present invention can also be implemented in an embodiment in which the adjusting process performed by the controller 60 in the glass manufacturing apparatus 1 is manually performed by an operator. Ｓ is calculated based on the raw material information, and atmospheric information (pO ２ , pH ２ O) can be measured and the SP value can be calculated. Furthermore, the operator can control at least one of the raw material blending apparatus 12, the oxygen supplying apparatus 41, and the steam supplying apparatus 51 based on the calculated SP value. Also, the operator may be responsible for only a part of the adjustment process of the controller 60.

[0065] The glass manufacturing method of the present invention preferably further comprises a forming step of forming the molten glass G to obtain a glass article. The molten glass G can be formed into any shape using any forming method. For example, glass for pharmaceutical containers can be formed into a tubular shape using the Danner method, the Bellow method, the downdraw method, etc. Furthermore, glass for displays can be formed into a plate shape using the overflow downdraw method, the slot downdraw method, the float method, the rollout method, etc.

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

[0067] The present invention will be described below based on examples. In these examples, the results of simulating the glass manufacturing method of the present invention using experimental apparatus J shown in Figure 2 are shown. Tables 1 to 6 show examples of the present invention (Nos. 1 to 20, 22 to 26, and 29 to 40) and comparative examples (Nos. 21, 27, and 28).

[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, capable of holding molten glass G therein, and having visible light transparency and heat resistance. The electric furnace E is a device for housing and heating the quartz container Q. The electric furnace E is equipped with an observation window through which the interior can be observed with a camera. The metal tube T is a platinum U-shaped tubular member having an outer diameter of 6 mm and a metal wall thickness of 0.8 mm. The bent portion of the metal tube T is immersed in the molten glass G in the quartz container Q. The interior of the metal tube T is configured so that a mixed gas having the composition and partial pressure listed in each table can be introduced from a gas inlet (Tin) at one opening to an outlet (Tout) at the other opening. That is, the metal tube T is a platinum member that comes into contact with the molten glass G and simulates the glass container 10 in the glass manufacturing apparatus 1 described above. The interior of the metal tube T simulates the enclosed space 21.

[0069] First, glass raw materials were prepared and mixed to obtain base glass batches of glass compositions a and b, as shown below. Glass composition a contained, in mass %, SiO ２73%, Al ２ O ３ 7%, B ２ O ３ 10%, CaO 1%, BaO 1%, Na ２ O 6%, K ２ The glass composition b is a borosilicate glass containing 2% of SiO in mass %. ２ 59.2%, Al ２ O ３ 19.3%, B ２ O ３ The base glass batches were each made of alkali-free glass containing 6.5% of sulfur, 2.5% of MgO, 6.3% of CaO, 0.5% of SrO, and 5.7% of BaO. Ｓ The sulfate raw material was externally added as necessary to adjust the glass batch for each example so as to satisfy the above.

[0070] The obtained glass batch was charged into a quartz container Q, which was then placed in an electric furnace E and heated for 10 minutes until a predetermined viscosity η was reached, to obtain molten glass G. Specifically, in the example of glass composition a, the glass was heated to a viscosity η of 720 dPa s. In the example of glass composition b, the glass was heated to a viscosity η of 890 dPa s.

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

[0072] Next, the gas shown in each table was injected from the gas inlet (Tin) of the metal tube T. ２ O, pO ２ , pN ２ The gas was supplied at 0.5 L / min so that the gas pressure became equal to or greater than 100 psi, and the gas was discharged from the outlet (Tout). This process was continued for 45 minutes. Thereafter, an image of the interface where the metal tube T and the molten glass G came into contact with each other was taken with a CCD camera (not shown) through an observation window of the electric furnace E and through the quartz container Q.

[0073] From the observation images of each example obtained in this manner, the foaming state was judged as follows: "A" if no foaming or expansion of bubble diameter was observed at the interface between the molten glass G and the metal tube T; "B" if the contraction of the bubble diameter was slow or the expansion of the bubble diameter was slight and no floating up was observed at the interface between the molten glass G and the metal tube T; and "C" if the floating up or detachment of bubbles was observed at the interface between the molten glass G and the metal tube T.

[0074] Furthermore, for the Examples and Comparative Examples in which bubbles were observed, the molten glass G was cooled to obtain a glass sample containing bubbles, and the main components of the gas in the bubbles were analyzed from the sample using a laser Raman spectrophotometer.

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081] As is clear from Tables 1 to 6, Examples 21, 27, and 28 had excessively large SP values, and therefore, ２ On the other hand, the SP value was suppressed in the other example, and as a result, the SO ２ Little or no foaming was observed.

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

[0083] REFERENCE SIGNS LIST 1 Glass manufacturing apparatus 10 Glass container 11 Raw material supply pipe 12 Raw material mixing apparatus 13 Glass delivery pipe 20 Enclosing container 21 Enclosing space 30 Regulating 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 measuring 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. A method for producing glass comprising a step of holding or flowing molten glass in contact with a metal wall made of platinum or a platinum alloy, the molten glass being heated to a temperature of 1000° C. ３ The sulfur concentration C of the molten glass is 0.05 (wt%) or less. Ｓ (wt%), the water vapor partial pressure pH of the space surrounding the metal wall ２ O (atm), and the oxygen partial pressure pO ２ (atm), the sulfur concentration C is set so that the value SP calculated by the formula (1) is SP≦3.

10. Ｓ , the water vapor partial pressure pH ２ O, and the oxygen partial pressure pO ２ The method for producing glass further comprises an adjusting step of adjusting at least one of SP=C. Ｓ ×pH ２ O / pO ２ (1) 2. In the adjustment step, the sulfur concentration C is adjusted so that 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 that 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 oxygen partial pressure pO ２ and an oxygen supplying means for supplying oxygen to the surrounding space, 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 water vapor partial pressure pH in the enclosed space of the metal wall ２ a water vapor partial pressure measuring means for measuring water vapor partial pressure pH O; and a water vapor supplying means for supplying water vapor to the surrounding space. 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 of, in mass %, 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 molding 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) 0 to less than 1% of ZnO (total amount of ZnO), 0 to 8% of MgO, 0 to 15% of CaO, 0 to 12% of SrO, and 0 to 15% of BaO.

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