JP2009073674A - Method for producing glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing glass which has optically high degree of homogeneity and where platinum foreign matter is hard to substantially increase when remelting. <P>SOLUTION: In the method for producing glass, a glass raw material batch is melted in a platinum vessel, a glass material is produced by forming and then the glass material is remelted in the platinum vessel. The selection of the glass raw material batch and/or the adjustment of melting conditions is performed so as to have a β-OH value of glass after remelting of 0.07/mm or more and 0.30/mm or less. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a glass manufacturing method, and more particularly to a glass manufacturing method used for optical pickup lenses of various optical disc systems such as CD, MD, DVD, video camera and general camera lens components.

Glasses of various compositions have been proposed as optical glasses used in optical pickup lenses for CD, MD, DVD and other various optical disk systems, video cameras and photographing lenses for general cameras. (For example, see Patent Documents 1 to 4)
This kind of glass is optically extremely homogeneous with no internal defects such as bubbles, foreign matter, striae, etc. as well as satisfying predetermined optical constants (refractive index, Abbe number). Is required.

Refractory melting containers are widely used for glass production. However, when melted in a refractory container, the refractory may erode and cause internal defects such as striae and bubbles in the glass. Therefore, it is common to use a platinum or platinum alloy container (hereinafter referred to as a platinum container) excellent in heat resistance and corrosion resistance for melting the optical glass. In particular, a glass raw material batch is melted in a platinum container and molded to produce a glass material once. Then, it is remelted in a platinum container and molded to obtain a glass product. High glass can be obtained.
JP 2000-302479 A JP 2004-292306 A JP 2005-15302 A JP 2005-139023 A Special table 2001-500098 gazette Japanese Patent No. 3485275 J. et al. H. Campbell et. al. , Elimination of Platinum Inclusions in Phosphate Laser Glasses, Lawrence Livermore National Laboratory, CA, UCRL-53932 (1989)

  When the glass is melted in the platinum container, minute foreign matters (hereinafter referred to as platinum bumps) due to the platinum container are likely to be generated in the glass. In particular, in the case where a method of once producing a material glass and remelting it, the amount of platinum is greatly increased by remelting. A large amount of platinum is a serious problem that can be a fatal defect for recent high-density image sensors.

  An object of the present invention is to provide a method for producing glass, which is optically high in homogeneity and hardly increases in platinum even when remelted.

  As a result of various experiments, the present inventors have found that the amount of water in the glass is closely related to the formation of platinum bumps, and have proposed the present invention.

  That is, the first glass production method of the present invention is such that the amount of platinum dissolved is 0.1 ppm or more and less than 100 ppm, and the β-OH value is 0.07 / mm or more and 0.30 / mm or less. The raw material batch is selected and / or the melting conditions are adjusted.

  In the first method, an appropriate melting equipment is selected, a glass raw material is appropriately selected, and melting is performed so that the platinum dissolution amount and β-OH value of the finally obtained glass are included in a predetermined range. It adjusts melting conditions such as temperature and melting time.

“Platinum dissolution amount” is measured by the following method. First, a crushed glass sample is decomposed with a mixed acid (HF, HCLO ₄ , HNO ₃ , HCl) and then heated and evaporated to dryness to obtain a salt. Nitric acid is added to the dried salt sample, classified, and platinum is analyzed and quantified with an ICP mass spectrometer.

  The “β-OH value” is an index indicating the amount of water in the glass, and can be expressed by the following formula.

β-OH value = (1 / X) log 10 (T ₁ / T ₂ )
X: Glass wall thickness (mm)
T ₁ : Transmittance (%) at a reference wavelength of 3846 cm ⁻¹ (= 2600 nm)
T ₂ : Minimal transmittance (%) in the vicinity of a hydroxyl group absorption wavelength of 3600 cm ⁻¹ (= 2800 nm) (range of 3400 cm ^{−1 to} 3700 cm ⁻¹ )
In the second glass production method of the present invention, a glass raw material batch is melted in a platinum container and molded to produce a material glass, and then the material glass is remelted in a platinum container and molded in a glass production method, The glass raw material batch is selected and / or the melting conditions are adjusted so that the β-OH value of the glass after remelting is 0.30 / mm or less, preferably 0.07 / mm or more and 0.30 / mm or less. It is characterized by that.

  In the second method, a glass raw material batch is once melted and vitrified to produce a raw material glass, which is then remelted to form a homogeneous glass to produce a high-quality glass product. At this time, select an appropriate melting equipment, select an appropriate glass raw material, and adjust melting conditions such as melting temperature and melting time so that the β-OH value of the glass after remelting is included in the predetermined range. To do. In addition, when remelting the material glass, in addition to the produced material glass, a different kind of glass may be added.

  The “container” is a general term for equipment that can accommodate molten glass inside. For example, crucibles in batch-type melting equipment, melting tanks in continuous melting equipment, clarification tanks, stirring tanks, fore-hearth, and the like are applicable. The term “platinum container” means a container having at least a contact surface with molten glass formed of platinum or a platinum alloy, and is not limited to a container made of platinum or a platinum alloy. Or a container covered with a platinum alloy foil.

  In the second method, it is preferable to further select the glass raw material batch, adjust the melting conditions, or select the melting equipment so that the β-OH value of the material glass is 0.35 / mm or less. .

  In the third glass production method of the present invention, a glass raw material batch is melted in a platinum container, molded to produce a material glass, then the material glass is remelted in a platinum container, and the glass production method for molding is performed. The glass raw material batch is selected and / or the melting conditions are adjusted so that the β-OH value of the material glass is 0.35 / mm or less, preferably 0.1 / mm or more and 0.35 / mm or less. And

  In the third method, as in the second method, the glass raw material batch is once melted and vitrified to produce a raw glass, which is then remelted to form a homogeneous glass to produce a high-quality glass product. Adopt the method to do. At this time, an appropriate melting facility is selected so that the β-OH value of the material glass is included in a predetermined range, a glass raw material is appropriately selected, and melting conditions such as a melting temperature and a melting time are adjusted. In addition, when remelting the material glass, in addition to the produced material glass, a different kind of glass may be added.

  Moreover, in said 2nd and 3rd method, it applies to the glass from which the platinum dissolution amount in raw material glass becomes 0.1 ppm or more, Preferably it is 0.5 ppm or more, Most preferably, it is 1 ppm or more, More preferably, it is 2 ppm or more. Is desirable.

  The glass raw material batch preferably contains 0.1 to 10% by mass of nitrate and / or 0.1 to 15% by mass of a raw material containing chlorine.

  The glass is preferably an alkali-containing silicate glass, particularly an alkali-containing borosilicate glass.

Examples of the glass raw material include SiO ₂ 5 to 75% by mass, B ₂ O _{3 3 to} 40%, RO (one or more selected from R: Ca, Sr, Ba, Zn) 2 to 30%, R ′. ₂ O (one or more selected from R ′: Li, Na, K) 0 to 12% glass, especially SiO ₂ 25 to 70% by mass%, B ₂ O _{3 3 to} 35%, RO (R : One or more selected from Ca, Sr, Ba, Zn) 5-30%, R ′ ₂ O (one or more selected from R ′: Li, Na, K) 0-12% glass Can be used. In consideration of the environment, it is desirable that the glass raw material batch does not substantially contain lead, arsenic, and fluoride. Here, “substantially does not contain” means that no active component is added except when it is inevitably mixed as an impurity. Specifically, it is preferable that the contents of lead, arsenic, and fluoride are each limited to less than 0.1% by mass. In the following description, “%” means “mass%” unless otherwise specified.

  The glass thus obtained is suitably used for optical glass applications or glass material applications for mold press molding glass.

  The glass of the present invention is manufactured by the above method.

  According to the method of the present invention, it is possible to produce a glass having high optical homogeneity and less platinum platinum. Therefore, it is suitable as a method for producing high-quality optical glass such as optical pickup lenses for CD, MD, DVD and other various optical disk systems, video cameras and photographing lenses for general cameras.

  In addition, a method called a mold press molding method is widely used for molding these lenses, but the method of the present invention is also suitable as a method for producing a glass material used for the mold press molding.

  According to the experiments by the present inventors, there is a certain relationship between the β-OH value of glass and platinum but, when the β-OH value of glass after remelting (glass product) is a certain value or more, it is remarkable. Generation of platinum bumps was observed. In addition, it was confirmed that the amount of platinum metal generated during remelting increases as the β-OH value of the material glass increases. From this result, it can be seen that if glass is produced so as to have a β-OH value of a certain value or less, the generation of platinum defects can be effectively suppressed.

  In addition, although the reason for platinum platinum increasing when the β-OH value of glass increases is not clear, it can be considered as follows, for example. That is, according to Patent Document 5, glass containing a large amount of moisture in the glass is likely to be foamed at the platinum interface due to the reaction between moisture and platinum. If this explanation is correct, it is considered that platinum is oxidized and becomes brittle due to the influence of this reaction, and that part peels off and falls off. It is also possible that platinum dissolved in the glass is reduced and deposited.

  In the method of the present invention, the β-OH value of the material glass is 0.35 / mm or less (especially 0.25 / mm or less, more preferably 0.24 / mm or less, and most preferably 0.23 / mm or less). And / or the β-OH value of the glass after remelting is 0.30 / mm or less (especially 0.25 / mm or less, more preferably 0.23 / mm or less, 0.20 / mm or less, optimally 0) .18 / mm or less is preferable), and each step is adjusted to produce glass. Moisture in the glass is mainly brought from the glass raw material and from the melting atmosphere. In the present invention, the melting equipment and the glass raw material are selected and the melting conditions are adjusted so that the β-OH value representing the moisture content of the glass is below a predetermined level.

  In addition, selection of glass raw materials and / or adjustment of melting conditions to reduce the β-OH value of glass after remelting to less than 0.07 / mm, or to reduce the β-OH value of material glass to less than 0.1 / mm. If done, the amount of platinum dissolved in the glass becomes very large, and the risk of precipitation of platinum is very high despite the extremely small β-OH value. Therefore, selection of glass raw materials and / or melting conditions so that the β-OH value in the glass after remelting is 0.07 / mm or more, or the β-OH value of the material glass is 0.1 / mm or more. It is preferable to perform the adjustment.

  Moreover, the platinum in glass originates in the melt | dissolution from the platinum container etc. which are used for glass manufacturing equipment. The smaller the amount of platinum dissolved in the material glass, the smaller the possibility of platinum fluttering during remelting. On the other hand, a material glass having a large amount of dissolved platinum is likely to generate platinum defects, and therefore has a great merit by applying the present invention. However, if the amount of platinum dissolved in the material glass exceeds 100 ppm (as a result, the amount of platinum dissolved in the glass after remelting exceeds 100 ppm), even when the method of the present invention is adopted, a large increase in platinum is suppressed. Becomes difficult. In particular, the platinum dissolution amount of the material glass and the glass after remelting is preferably 50 ppm or less. Furthermore, 20 ppm or less is preferable, and 10 ppm or less is more preferable.

  Hereinafter, the method will be specifically described for each process.

  First, a glass raw material batch is prepared.

A glass raw material batch mixes various raw materials so that it may become a desired composition. Although the method of the present invention can be applied to various glass materials and is not limited to a specific composition, borosilicate glass widely used especially for optical glass can be preferably used. The “borosilicate glass” referred to in the present invention is a glass containing 5% or more, particularly 20% or more of SiO ₂ and 3% or more of B ₂ O ₃ . When a large amount of boric acid is contained, the β-OH value of the glass tends to increase because the boric acid raw material easily absorbs water. Therefore, it is effective to apply the present invention when manufacturing borosilicate glass. It can also be suitably applied to alkali-containing silicate glass. The “alkali-containing silicate glass” referred to in the present invention is a glass containing 5% or more, particularly 20% or more of SiO ₂ and containing an alkali metal component. Since this type of glass contains an alkali metal component, it easily reacts with platinum, and the amount of dissolved platinum is relatively high. Therefore, there is a higher risk of platinum defects than silicate glass containing no alkali. Therefore, a great merit can be obtained by applying the present invention. Naturally, when the present invention is applied to the production of an alkali-containing borosilicate glass containing B ₂ O ₃ and an alkali metal component, the effects of the present invention can be fully enjoyed. The “alkali-containing borosilicate glass” referred to in the present invention is a glass containing 5% or more of SiO ₂ , 3% or more of B ₂ O ₃ and an alkali metal component.
Note that a glass having a low melting point like the alkali-containing glass, specifically, a glass having a softening point of 650 ° C. or less is likely to react with platinum and has a high risk of generating platinum defects. Therefore, a great merit can be enjoyed by applying the present invention also to such a glass.

Examples of glass compositions that can enjoy the effects of the present invention include, for example, lead, arsenic, and fluoride,
(1) By mass%, SiO ₂ 5 to 75%, B ₂ O _{3 3 to} 40%, RO (R: one or more selected from Ca, Sr, Ba, Zn) 2 to 30%, R ′ ₂ O ( R ′: one or more selected from Li, Na, K) Borosilicate glass containing 0-12%,
(2) By mass%, SiO ₂ 10 to 70%, B ₂ O _{3 3 to} 35%, RO (one or more selected from R: Ca, Sr, Ba, Zn) 5 to 30%, R ′ ₂ O ( R ′: one or more selected from Li, Na, K) Borosilicate glass containing 0-12%,
(3) Alkali-containing borosilicate glass containing SiO ₂ 25 to 55% by mass%, B ₂ O _{3 3 to} 27%, RO 10 to 30%, R ′ ₂ O 5 to 12%,
(4) SiO ₂ 25~55% by _{mass%, Al 2 O 3 0.5~8%} , B 2 O 3 5~25%, RO 10~30%, CaO 4~10%, SrO 0~15% R ′ ₂ O 5-12%, La ₂ O ₃ 0-20% alkali-containing borosilicate glass,
(5) SiO ₂ 25 to 55% by mass, B ₂ O ₃ 19 to 25%, Al ₂ O ₃ 0.5 to 8%, RO 12 to 27%, CaO 4 to 10%, SrO 0 to 15% , R ′ ₂ O 5-10%, La ₂ O ₃ 0.5-15% containing alkali-containing borosilicate glass,
(6) Alkali-containing lanthanum containing 5 to 50% SiO ₂ , 20 to 30% B ₂ O ₃ , 15 to 30% RO, 3 to 12% R ′ ₂ O and 10 to 50% La ₂ O _{3 by} mass% Borosilicate glass,
(7) Alkali-containing borosilicate glass containing SiO ₂ 35 to 75%, B ₂ O _{3 3 to} 25%, RO 5 to 30%, R ′ ₂ O 5 to 10% by mass% is preferable.

  The reason for determining the composition range as described above will be described below.

As the amount of SiO ₂ increases, the solubility of platinum in glass tends to decrease, and the amount of platinum dissolved tends to fall below 0.1 ppm or 2 ppm. For this reason, SiO ₂ is preferably 5% or more, 10% or more, 20% or more, 25% or more, particularly 35% or more. However, if there is too much SiO ₂ , the melting temperature becomes high and the moisture in the glass tends to dissipate (as a result, the β-OH value becomes very low), so the merit of applying the present invention becomes small. . The amount of SiO _{2 in the} glass that can sufficiently enjoy the effects of the present invention is preferably 75% or less, 70% or less, 60% or less, 55% or less, particularly 50% or less.

When B ₂ O ₃ is small, β-OH introduced into the glass is small, so that the merit of applying the present invention is small. On the other hand, when there is too much B ₂ O ₃ , the melting temperature is lowered and the amount of platinum dissolved in the glass is reduced, so that the merit of applying the present invention is reduced. The amount of B ₂ O _{3 in the} glass that can fully enjoy the effects of the present invention is preferably 3% or more, 5% or more, 10% or more, 19% or more, particularly preferably 20% or more, and 40% or less, 35 % Or less, 30% or less, 27% or less, and particularly preferably 25% or less.

  RO (R: one or more selected from Ca, Sr, Ba, Zn) is a component that affects the amount of platinum dissolved in the glass. The total RO content is 2% or more, 5% or more, 10% or more, 12% or more, preferably 15% or more, preferably 30% or less, 27% or less, particularly 25% or less. Is preferred. Specifically, CaO is preferably 4 to 10%, and SrO is preferably 0 to 15%.

R ′ ₂ O (R ′: one or more selected from Li, Na, K) is also a component that affects the amount of platinum dissolved in the glass, like RO. The effect is greater than RO. R ′ ₂ O is not an essential component, but its total content is preferably 3% or more, particularly 5% or more, and preferably 12% or less, particularly 10% or less.

Al ₂ O ₃ is not an essential component but is preferably contained in an amount of 0.5% or more, more preferably 15% or less, and particularly preferably 8% or less.

La ₂ O ₃ is not an essential component but is preferably contained in an amount of 0.5% or more, particularly 10% or more, and is 50% or less, 40% or less, 30% or less, 20% or less, particularly 15% or less. It is preferable.

Moreover, the glass of said (1)-(7) can add a various component besides the said component. Furthermore, it is applicable also to the glass which has composition systems other than the illustrated silicate glass, borosilicate glass, alkali-containing borosilicate glass, and alkali-containing lanthanum borosilicate glass. In addition, so-called phosphate glass containing 5% or more of P ₂ O ₅ has high reactivity with platinum, but since there is almost no possibility that dissolved platinum is precipitated and platinum platinum is generated. The merit to apply is very small. However, application of the present invention to phosphate glass is not excluded.

  In selecting the glass raw material, it is desirable to select the raw material so that the water content is as low as possible. For example, hydroxide introduces moisture into glass and should be avoided as much as possible. On the other hand, an anhydrous compound is preferable because it does not contain moisture.

  Moreover, it is preferable to use nitrate as a raw material. The proportion is 0.1 to 10% by mass, preferably 0.1 to 5% by mass, based on the whole batch. If nitrate is used, since the nitric acid volatilizes together with the hydroxyl group when the glass is melted, the moisture content of the glass can be reduced. If the ratio of nitrate is 0.1% by mass or more, the above effect can be expected. However, using more than 10% by mass is not preferable because the amount of platinum dissolved in the glass from the platinum container increases.

  Use of a raw material containing chlorine is also effective in reducing moisture in the glass. When the chlorine-containing raw material is contained, moisture in the glass is reduced because chlorine volatilizes together with the hydroxyl group when the glass is melted. The ratio of the chlorine-containing raw material is 0.1 to 15% by mass, preferably 0.1 to 8% by mass. If the content of the chlorine-containing raw material is 0.1% by mass or more, the above effect can be expected. However, if it exceeds 15 mass%, the chlorine concentration in the glass product becomes too high, which may corrode the mold during press molding. Moreover, there is a concern that the weather resistance of the glass product will be lowered.

  Next, the glass raw material batch is melted in a platinum container. As a means to lower the β-OH value of the glass during melting, a method such as bubbling a halogen atom-containing gas (fluorine gas or chlorine gas) or an inert gas (argon gas or nitrogen gas) at the time of melting is effective. is there. It is desirable to select a heating method that reduces the moisture in the atmosphere as much as possible. For example, when the glass is melted by heating with a burner, the amount of moisture in the atmosphere can be reduced by adopting the air combustion method rather than the oxyfuel combustion method. Further, if part of the burner heating is switched to electric melting, the amount of moisture in the atmosphere can be further reduced.

  Next, molten glass is formed to produce a material glass. The forming of the material glass is not particularly limited. What is necessary is just to shape | mold in the shape convenient for remelting, for example, what is necessary is just to shape | mold in the marble form, flake form, powder form, film form etc.

  In this way, the material glass is once produced. The moisture content of the produced material glass is controlled by selecting a glass raw material batch, adjusting a melting condition, or the like. As a result, the β-OH value of the material glass is preferably adjusted to 0.35 / mm or less, more preferably 0.25 / mm or less, still more preferably 0.24 / mm or less, particularly 0.23 / mm or less. can do. By setting the β-OH value of the material glass to 0.35 / mm or less, it is possible to prevent a large amount of platinum from being deposited in the subsequent remelting step.

  Subsequently, the material glass is remelted in a platinum container. By performing remelting, it is possible to obtain a glass with extremely high homogeneity. Also in the case of remelting, it is desirable to adjust or select the melting conditions and the melting equipment so as to adjust the β-OH value of the glass after remelting to be within a predetermined range as described above.

  Thereafter, the molten glass is formed into a desired shape to obtain the target glass.

  The obtained glass has a moisture content controlled by selecting a glass raw material batch, adjusting a melting condition, or the like. As a result, the β-OH value of the glass finally obtained is 0.30 / mm or less, 0.25 / mm or less, 0.23 / mm or less, 0.20 / mm or less, 0.18 / mm or less. It becomes possible to adjust. If the β-OH value of the glass after remelting is adjusted to be 0.30 / mm or less, the amount of platinum contained in the glass will not increase significantly even if remelted.

  In addition, the produced glass does not necessarily need to be formed into a shape to be finally used. For example, when it is used as a glass material for mold press molding, it may be molded into a shape suitable for mold press molding.

  Hereinafter, the present invention will be described based on examples. Table 1 shows the composition of the glass used in this experiment. Tables 2 to 5 show examples of the present invention (Examples 1 to 8, 11 to 16) and comparative examples (Examples 9 and 10).

  Each sample was prepared as follows. First, silicon oxide, aluminum oxide, boric anhydride, orthoboric acid, barium carbonate, barium nitrate, calcium carbonate, so as to have the composition shown in Table 1 (the numerical values shown in Table 1 mean “% by mass”). Strontium carbonate, zinc oxide, lithium carbonate, soda ash, sodium nitrate, lanthanum oxide, and antimony trioxide were prepared. In addition, about the sodium raw material (soda ash, sodium nitrate), the barium raw material (barium carbonate, barium nitrate), and the boric acid raw material (anhydrous boric acid, orthoboric acid), the ratio of the used raw material was shown in Tables 2-5, respectively. Next, the raw material batch was put in a platinum crucible and melted in the air under the conditions shown in Tables 2 to 5. Thereafter, the molten glass was poured out on a carbon table and formed into a plate shape. About the obtained raw material glass, the beta-OH value and the platinum dissolution amount were measured. The number of platinum spots was counted.

  Subsequently, after each material glass was pulverized, it was put into a platinum crucible and remelted. Thereafter, the molten glass was poured out on a carbon table and formed into a plate shape. About the obtained glass sample, (beta) -OH value and platinum dissolution amount were measured. Moreover, the platinum amount was counted and the increase amount of the platinum amount before and after remelting was calculated.

  The results of evaluation are shown in each table. Table 1 shows the relationship between the β-OH value of the material glass and the number of platinum spots before and after remelting, and the β-OH value of the glass sample (glass after remelting) and the number of platinum spots contained in the sample. Table 2 shows the relationship.

As is apparent from the table, the glasses A to F have different glass compositions, but in either case, the lower the β-OH value of the material glass, the more the increase in platinum but due to remelting tends to be suppressed. I understand. Similarly, it can be confirmed that the lower the β-OH value of the finally obtained glass, the smaller the amount of platinum contained in the glass. Further, as shown in Examples 9 and 10, when the product was produced so that the β-OH value was 0.35 / mm or more, the number of platinum spots in the product increased by 100 pieces / cm ³ or more. On the other hand, in the product produced so that the β-OH value was less than 0.35 / mm, the platinum content was as small as 53.4 pieces / cm ³ or less.

  The β-OH value was measured as follows. First, the produced material glass or glass sample was cut into a size of 20 × 20 × 2 mm, the surface was processed into a mirror surface with cerium polishing powder, and then the transmission spectrum was measured using FT-IR. Then, it computed using the following formula | equation.

β-OH value = (1 / X) log 10 (T ₁ / T ₂ )
X: Glass wall thickness (mm)
T ₁ : Transmittance (%) at a reference wavelength of 3846 cm ⁻¹ (= 2600 nm)
T ₂ : Minimal transmittance (%) in the vicinity of a hydroxyl group absorption wavelength of 3600 cm ⁻¹ (= 2800 nm) (range of 3400 cm ^{−1 to} 3700 cm ⁻¹ )
The amount of platinum dissolved was measured as follows. First, the crushed glass sample was decomposed with a mixed acid (HF, HCLO ₄ , HNO ₃ , HCl) and then evaporated by heating to dryness to obtain a salt. Next, nitric acid was added to the dried salt sample and classified, followed by analysis and quantification using an ICP mass spectrometer.

The number of platinum bumps was determined as follows. First, the produced material glass or glass sample was cut into 35 × 35 × 15 mm, the surface was processed into a mirror surface with cerium polishing powder, and then placed on a microscope sample stage. Further, parallel light was incident from the side of the sample, platinum platinum was counted, and converted to the number per 1 cm ³ .

It is a graph which shows the relationship between (beta) -OH value of raw material glass, and the increase amount of platinum but before and after remelting. It is a graph which shows (beta) -OH value of the glass after remelting, and the relationship between the number of platinum spots contained in the glass.

Claims (20)

  The glass raw material batch is selected and / or the melting conditions are adjusted so that the platinum dissolution amount is 0.1 ppm or more and less than 100 ppm and the β-OH value is 0.07 / mm or more and 0.30 / mm or less. A method for producing glass, characterized in that.   In a glass manufacturing method in which a glass raw material batch is melted in a platinum container and molded to produce a raw material glass, and then the raw material glass is remelted in a platinum container and molded, the β-OH value of the glass after remelting is A glass production method comprising selecting a glass raw material batch and / or adjusting a melting condition so as to be 0.30 / mm or less.   The glass raw material batch is selected and / or the melting conditions are adjusted so that the β-OH value of the glass after remelting is 0.07 / mm or more and 0.30 / mm or less. Glass manufacturing method.   The method for producing glass according to claim 2 or 3, wherein the glass raw material batch is selected and / or the melting conditions are adjusted so that the β-OH value of the material glass is 0.35 / mm or less.   In a glass manufacturing method in which a glass raw material batch is melted in a platinum container and molded to produce a raw material glass, and then the raw material glass is remelted in a platinum container, and the glass has a β-OH value of 0.35. Glass manufacturing method, wherein the glass raw material batch is selected and / or the melting conditions are adjusted so as to be equal to or less than / mm.   The glass production according to any one of claims 2 to 5, wherein the glass raw material batch is selected and / or the melting conditions are adjusted so that the amount of platinum dissolved in the material glass is 0.1 ppm or more and less than 100 ppm. Method.   The glass raw material batch containing 0.1-10 mass% of nitrate is used, The manufacturing method of the glass in any one of Claims 1-6 characterized by the above-mentioned.   The method for producing glass according to any one of claims 1 to 7, wherein a glass raw material batch containing 0.1 to 15% by mass of a raw material containing chlorine is used.   The method for producing a glass according to any one of claims 1 to 8, wherein the glass obtained is borosilicate glass, alkali-containing silicate glass, or alkali-containing borosilicate glass. SiO ₂ 5 to 75% by mass%, B ₂ O _{3 3 to} 40%, RO (R: one or more selected from Ca, Sr, Ba, Zn) 2 to 30%, R ′ ₂ O (R ′: 1 or more types chosen from Li, Na, and K) The glass raw material batch prepared so that it may become glass containing 0-12% is used, The manufacture of the glass in any one of Claims 1-9 characterized by the above-mentioned. Method. SiO ₂ 25 to 70% by _{mass%, B 2 O 3 3~35%} , RO (R: Ca, Sr, Ba, 1 or more selected from _{Zn) 5~30%, R '2} O (R': 1 or more types chosen from Li, Na, and K) The glass raw material batch prepared so that it may become glass containing 0-12% is used, The manufacture of the glass in any one of Claims 1-10 characterized by the above-mentioned. Method.   It is a manufacturing method of optical glass, The manufacturing method of the glass in any one of Claims 1-11 characterized by the above-mentioned.   It is a manufacturing method of the glass material for mold press molding, The manufacturing method of the glass in any one of Claims 1-12 characterized by the above-mentioned.   A glass produced by the method according to claim 1.   A glass having a platinum dissolution amount of 0.1 ppm or more and less than 100 ppm and a β-OH value of 0.07 / mm or more and 0.30 / mm or less.   The glass of claim 15 which is a silicate glass. SiO ₂ 5 to 75% by mass%, B ₂ O _{3 3 to} 40%, RO (R: one or more selected from Ca, Sr, Ba, Zn) 2 to 30%, R ′ ₂ O (R ′: The glass according to claim 15 or 16, wherein a glass raw material batch prepared so as to be a glass containing 0 to 12% is selected from Li, Na and K. SiO ₂ 25 to 70% by _{mass%, B 2 O 3 3~35%} , RO (R: Ca, Sr, Ba, 1 or more selected from _{Zn) 5~30%, R '2} O (R': 1 or more types chosen from Li, Na, K) 0-12% is contained, Glass in any one of Claims 15-17 characterized by the above-mentioned.   The glass according to claim 15, which is an optical glass.   The glass according to any one of claims 15 to 19, which is a glass material for mold press molding.

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