WO2008029799A1

WO2008029799A1 - Process for producing glass

Info

Publication number: WO2008029799A1
Application number: PCT/JP2007/067204
Authority: WO
Inventors: Satoko Konoshita; Fumio Sato; Akihiko Sakamoto
Original assignee: Nippon Electric Glass Co., Ltd.
Priority date: 2006-09-04
Filing date: 2007-09-04
Publication date: 2008-03-13
Also published as: CN101511742B; CN101511742A

Abstract

A process for producing a glass that is high in optical homogeneity degree and when remelted inhibits any substantial increase of platinum granules. There is provided a process for producing glass through melting of a glass raw material batch in a platinum vessel, molding into a preform glass, remelting of the preform glass in a platinum vessel and molding, characterized in that selection of the glass raw material batch and/or regulation of melting conditions is carried out so that the β-OH value of the glass after remelting is 0.30 /mm or less.

Description

Specification

Glass manufacturing method

Technical field

TECHNICAL FIELD [0001] The present invention relates to a glass manufacturing method, and more particularly to a glass manufacturing method used for optical pickup lenses of CD, MD, DVD and other various optical disk systems, video camera and general camera photographing lens components, and the like.

Background art

[0002] Glasses of various composition systems have been proposed as optical glasses used for optical pickup lenses of CD, MD, DVD and other various optical disk systems, and video cameras as photographing lenses for general cameras. (For example, see Patent Documents 1 to 4)

[0003] This kind of glass not only satisfies a predetermined optical constant (refractive index, Abbe number), but also has an optically very homogeneous degree free from internal defects such as bubbles, foreign matter, and striae. It is required to be high glass.

[0004] Melting containers made of refractory are widely used for glass production. However, when melted in a refractory container, the refractory is eroded and can cause internal defects such as bubbles in the glass. Therefore, for melting optical glass, it is common to use a platinum or platinum alloy container (hereinafter referred to as a platinum container) having excellent heat resistance and corrosion resistance. In particular, a glass raw material batch is melted in a platinum container and molded to produce a glass material once, and then remelted in a platinum container and molded to obtain a glass product. High glass can be obtained.

Patent Document 1: Japanese Published Patent: JP 2000-302479 A

Patent Document 2: Japanese Published Patent: Japanese Unexamined Patent Application Publication No. 2004-292306

Patent Document 3: Japanese Published Patent: JP 2005-15302

Patent Document 4: Japanese Patent: JP 2005-139023

Patent Document 5: Japanese Published Patent: Special Table 2001-500098

Patent Document 6: Japanese Published Patent: Japanese Patent No. 3485275

Non-Patent Document 1: JH Campbell et. Al., Elimination of Platinum Inclusio ns in Phosphate Laser Glasses, Lawrence Livermore National Labor atory, CA, UCRL- 53932 (1989)

Disclosure of the invention

Problems to be solved by the invention

[0005] When glass is melted in a platinum container, minute foreign substances (hereinafter referred to as platinum bush) due to the platinum container are likely to be generated in the glass. In particular, when a method of once producing a glass material and remelting it is used, the amount of platinum is greatly increased by remelting. A large amount of white gold is a serious problem that can be a fatal defect for recent high-density image sensors.

[0006] An object of the present invention is to provide a glass manufacturing method in which the homogeneity is optically high and the platinum bushing is hardly increased even after remelting.

Means for solving the problem

[0007] As a result of various experiments, the present inventors have found that the amount of water in the glass is related to the formation and close adhesion of platinum bush and came to propose the present invention.

[0008] That is, in the first glass production method of the present invention, the amount of platinum dissolved is 0.1 lppm or more and less than lOOppm, and the β-OH value is 0 · 07 / mm or more and 0 · 30 / mm or less. In addition, the glass raw material batch is selected and / or the melting conditions are adjusted.

[0009] In the first method, an appropriate melting equipment is selected and a glass raw material is appropriately selected so that the platinum dissolution amount and / 3—OH value of the finally obtained glass are included in a predetermined range. Shi

Also, the melting conditions such as the melting temperature and the melting time are adjusted.

“Platinum dissolution amount” is measured by the following method. First, a ground glass sample is decomposed with a mixed acid (HF, HCLO, HNO, HC1) and then evaporated by heating to dryness to obtain a salt. Dry

4 3

Add the nitric acid to the solid salt sample, classify it, and analyze and quantify platinum with the ICP mass spectrometer `` / 3-OH gj is an indicator of the amount of water in the glass and can be expressed by the following equation: [0011] / 3—OH value = (l / X) loglO (T / T)

1 2

X: Glass wall thickness (mm) T: Transmittance (%) at reference wavelength 3846cm— ¹ (= 2600nm)

T: hydroxyl absorption near 3600cm- ¹ (= 2800nm) (3400cm- ¹ to 3700cm- ¹

2

Range) (%)

[0012] The second glass production method of the present invention is a method for producing glass in which a glass raw material batch is melted in a platinum container and molded to produce a material glass, and then the material glass is re-melted in a platinum container. In the method, the selection of the glass raw material batch and / or the melting conditions 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 adjusting.

[0013] In the second method! /, Once the glass raw material batch is melted and vitrified to produce a raw glass, this is remelted to form a homogeneous glass, and a high-quality glass product is obtained. Adopt the production method. At this time, select an appropriate melting equipment, select an appropriate glass raw material so that the / 3-OH value of the glass after remelting falls within the specified range, and select the melting conditions such as melting temperature and melting time. Adjust. When remelting the material glass, it is possible to add a different kind of glass in addition to the produced material glass.

[0014] "Container" is a general term for equipment that can accommodate molten glass inside. For example, crucibles in batch-type melting equipment, melting tanks in refining melting equipment, clarification tanks, agitation tanks, forehouses, etc. “Platinum container” means a container in which at least the contact surface with molten glass is formed of platinum or a platinum alloy, and is not limited to a container of platinum or a platinum alloy force. Or a container covered with platinum alloy foil.

[0015] In the second method, the glass raw material batch is selected, the melting conditions are adjusted, and the melting equipment is selected so that the β-OH value of the material glass is 0.35 / mm or less. It is preferable.

[0016] The third glass production method of the present invention is a method for producing glass in which a glass raw material batch is melted in a platinum container and molded to produce a material glass, and then the material glass is re-melted in a platinum container. In the method, the glass raw material batch is selected and / or the melting condition is adjusted so that the / 3-OH value of the material glass is 0.35 / mm or less, preferably 0.1 / mm or more and 0.35 / mm or less. It is characterized by performing. [0017] In the third method, as in the second method, the glass raw material batch is once melted and made into glass to produce a material glass, which is then remelted to form a homogeneous glass. Adopt the method of manufacturing glass products. At this time, select an appropriate melting facility, select an appropriate glass raw material, and adjust the melting conditions such as melting temperature and melting time so that the / 3-OH value of the material glass is within the specified range. When remelting the material glass, in addition to the produced material glass, a different kind of glass may be added.

[0018] In the second and third methods, the amount of platinum dissolved in the material glass is 0.1 lppm or more, preferably 0.5 ppm or more, particularly preferably 1 ppm or more, and more preferably 2 ppm or more. It is desirable to apply to glass.

[0019] The glass raw material batch preferably contains 0.;! To 10% by mass of nitrate and / or a raw material containing chlorine of 0.;! To 15% by mass.

[0020] The glass is preferably an alkali-containing silicate glass, particularly an alkali-containing borosilicate glass.

[0021] Examples of the glass raw material include SiO 5 to 75%, B 2 O 3 to 40% by mass%, RO (R: Ca,

2 2 3

Sr ,: 1 or more selected from Ba, Zn) 2-30%, R 'O (R': selected from Li, Na, K 1

2

More than seeds) 0 ~; Glass containing 12%, especially SiO 25-70% by mass%, B O 3 ~ 3

2 2 3

5%, RO (R: Ca, Sr ,: one or more selected from Ba, Zn) 5-30%, R '〇 (R ,: Li, Na

2

, One or more selected from K) 0 ~; It is possible to use a glass formulated to contain 12% glass. In consideration of the environment, it is desirable that the glass raw material batch contains substantially no lead, arsenic or fluoride. Here, “substantially free” means that no active ingredients are added unless it is inevitably mixed in as an impurity. Specifically, it is preferable that the content of lead, arsenic, and fluoride is limited to less than 0.1% by mass. In the following description, “%” means “mass%” unless otherwise specified.

[0022] The glass thus obtained is suitably used for optical glass or glass material for mold press molding glass.

The glass of the present invention is manufactured by the above method. The invention's effect [0023] According to the method of the present invention, it is possible to produce a glass having high optical homogeneity and less 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.

[0024] For molding these lenses, a method called a mold press molding method is widely adopted, but the method of the present invention is suitable as a method for producing a glass material used for the mold press molding. .

BEST MODE FOR CARRYING OUT THE INVENTION

[0025] According to the experiments by the present inventors, there is a fixed relationship between the / 3—OH value of glass and platinum bush, and the / 3—OH value of glass (glass product) after remelting is above a certain value. In the case of, significant white gold generation was observed. It was also confirmed that the amount of platinum black generated during remelting increased as the / 3—OH value of the material glass increased. From this result, if the glass is produced so that the / 3—OH value is below a certain value, the generation of platinum batter can be effectively suppressed.

[0026] It is not clear why the platinum content increases as the β-OH value of the glass increases, but it can be considered, for example, as follows. 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, the influence of this reaction will cause the gold to oxidize and become brittle, and that part will peel and drop off. It is also possible that platinum dissolved in the glass is reduced and deposited.

[0027] In the method of the present invention, the 13 OH value of the material glass is 0.35 / mm or less (especially 0.25 / mm or less, further 0.24 / mm or less, optimally 0.23 / mm or less. Preferred), and / or after remelting, the / 3 OH value of the glass is 0.30 / mm or less (especially 0.25 / mm or less, furthermore 0.23 / mm or less, 0.20 / mm or less, Optimally, it is preferably 0.18 / mm or less), and the glass is produced by adjusting each step so that Moisture in the glass is mainly brought from the glass raw material and melted 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 / 3-OH value representing the moisture content of glass is below a predetermined level. [0028] It should be noted that selection of the glass raw material and / or adjustment of the melting conditions to reduce the β OH value of the glass after remelting to less than 0 · 07 / mm, or the β β value of the material glass to less than 0.1 / mm. When the preparation is performed, the amount of platinum dissolved in the glass becomes very large, and the risk of precipitation of platinum is very high even though the β OH value is extremely small. 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.

[0029] Platinum in glass is caused by melting from a platinum container or the like used in a glass production facility. The smaller the amount of platinum dissolved in the material glass, the smaller the possibility that platinum will occur during remelting. On the other hand, a material glass having a large amount of platinum dissolved is likely to generate platinum batter, and thus has a great merit by applying the present invention. However, if the amount of platinum dissolved in the material glass exceeds 1 OOppm (as a result, the amount of platinum dissolved in the glass after remelting exceeds 1 OOppm), even when the method of the present invention is adopted, the platinum amount increases significantly. It becomes difficult to suppress. 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.

[0030] Hereinafter, the method will be specifically described for each process.

[0031] First, a glass raw material batch is prepared.

[0032] In the glass raw material batch, various raw materials are prepared so as to have a desired composition. The method of the present invention can be applied to various glass materials, and is not limited to a specific composition, but borosilicate glass widely used especially for optical glass can be preferably used. The “borosilicate glass” as used in the present invention contains 5% or more, particularly 20% or more of SiO, and 3% of B 2 O.

2 2 3

% Glass or more. When a large amount of boric acid is contained, the / 3-OH value of the glass tends to increase because the boric acid raw material easily absorbs water. Therefore, it is effective if the present invention is applied to the production of borosilicate glass. It can also be suitably applied to alkali-containing silicate glasses. In the present invention, “alkali-containing silicate glass” is composed of 5% SiO.

A glass containing 2 or more, particularly 20% or more, and containing an alkali metal component. This type of glass contains an alkali metal component, so it has a relatively high amount of platinum that easily reacts with platinum. Therefore, it does not contain alkali! /, And there is a high risk of platinum platinum formation compared to silicate glass. Therefore, a great merit can be obtained by applying the present invention. Naturally, for the production of alkali-containing borosilicate glass containing BO and alkali metal components.

twenty three

When the present invention is applied, the effects of the present invention can be enjoyed to the maximum. The “alkali-containing borosilicate glass” as used in the present invention is composed of 5% or more of SiO, 3% or more of B 2 O, and an alkali metal component.

2 2 3

Glass containing minutes.

[0033] It is to be noted that a glass having a low melting point, specifically a glass having a softening point of 650 ° C or lower, similarly to the alkali-containing glass, has a high risk of reacting with platinum and immediately producing platinum. Therefore, it is possible to enjoy great merits by applying the present invention to such glass.

Yes

[0034] Examples of glass compositions capable of enjoying the effects of the present invention include, for example, lead, arsenic, and fluoride,

(1) By mass% SiO 5—75%, B 3 O 3-40%, RO (R: selected from Ca, Sr, Ba, Zn

2 2 3

2 to 30%, R '〇 (R': one or more selected from Li, Na, K) 0 to 12%

2

A borosilicate glass containing,

(2) Weight ^_0/0 in SiO 10-70%, BO 3~35%, RO (R: Ca, Sr ,: Ba, Zn force, et chosen

2 2 3

5-30%, R '〇 (R': one or more selected from Li, Na, K) 0-; 12%

2

A borosilicate glass containing,

(3) By mass% SiO 25-55%, B 3 3-27%, RO 10-30%, R'O 5 ~; 12

2 2 3 2

Alkali-containing borosilicate glass containing

(4) By mass% SiO 25-55%, Al O 0.5-5%, B O 5-25%, RO 10-3

2 2 3 2 3

0%, CaO 4-10%, SrO 0-15%, R'O 5-12%, La O 0-20%

2 2 3

Alkali-containing borosilicate glass,

(5) By mass% SiO 25-55%, B O 19-25%, Al O 0.5-5%, RO 12 ~

2 2 3 2 3

27%, CaO 4-10%, SrO 0-15%, R'O 5-10%, La O 0.5 ~; 15% included

2 2 3

Having an alkali-containing borosilicate glass,

(6) By mass, SiO 5-50%, B 2 O 20-30%, RO 15-30%, R 'O 3 ~; 12

2 2 3 2

%, La O 10-50% alkali-containing lanthanum borosilicate glass, (7) By mass% SiO 35-75%, BO 3-25%, RO 5-30%, R, O 5-10%

2 2 3 2

An alkali-containing borosilicate glass to be contained is suitable.

[0035] The reason for determining the composition range as described above will be described below.

[0036] As the amount of SiO increases, the solubility of platinum in glass decreases, and the amount of platinum dissolved becomes 0.1 ppm.

2

Or tend to be below 2ppm. For this reason, SiO is 5% or more, 10% or more, 20% or less

2

In addition, it is preferably 25% or more, particularly 35% or more. However, if too much SiO is melted

2

As the temperature increases, the moisture in the glass tends to dissipate (as a result, the β OH value becomes very low), so that the merit of applying the present invention is reduced. The amount of SiO in the glass that can fully enjoy the effects of the present invention is 75% or less, 70% or less, 60% or less, 55% or less, especially 50%.

2

It is preferable to be less than%.

[0037] When the amount of B 2 O is small, β OH introduced into the glass is small, so the present invention is applied.

twenty three

Merit power S to be smaller. On the other hand, if there is too much B 2 O, the melting temperature decreases and platinum gas is reduced.

twenty three

Since the amount of melt into the lath is reduced, the merit of applying the present invention is reduced. The amount of B 2 O in glass that can fully enjoy the effects of the present invention is 3% or more, 5% or more, 10% or more, 1

twenty three

It is preferably 9% or more, particularly 20% or more, and preferably 40% or less, 35% or less, 30% or less, 27% or less, particularly 25% or less.

[0038] 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, particularly preferably 15% or less, 30% or less, 27% or less, especially 25% or less. It is preferable. Specifically, CaO is preferably 4 to 10%, and SrO 0 to 15%.

[0039] R'0 (R ': one or more selected from Li, Na, K) is also dissolved in platinum in the same manner as RO.

2

It is a component that affects the amount of penetration. The impact is greater than RO. R'O is essential

2

Although it is not a minute, the total content is preferably 3% or more, particularly preferably 5% or more. It is preferably 12% or less, particularly preferably 10% or less.

[0040] Al O is not an essential component, but it is preferable to contain 0.5% or more, and 15% or less.

twenty three

In particular, it is preferably 8% or less.

[0041] La O is not an essential component, but 0.5% or more, particularly 10% or more is preferable. In addition, it is preferably 50% or less, 40% or less, 30% or less, 20% or less, particularly 15% or less.

[0042] In addition to the above components, various components may be added to the glasses of the above (1) to (7). Furthermore, the present invention can also be applied to glasses having a composition system other than the exemplified 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 PO has high reactivity with platinum.

twenty five

However, the merit of applying the present invention is very small because there is almost no possibility that the dissolved platinum is precipitated and platinum platinum is generated. However, application of the present invention to phosphate glass is not excluded.

[0043] 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 the glass and should be avoided as much as possible. On the other hand, an anhydrous compound is preferable because it does not contain moisture.

[0044] It is preferable to use nitrate as a raw material. Its proportion of the whole batch 0.1 to; 10 mass ^_0/0, preferably 0.5; a ~ 5 wt%!. When nitrate is used, nitric acid volatilizes with the hydroxyl group when the glass is melted, so that the moisture content of the glass can be reduced. The above effect can be expected when the ratio of nitrate is 0.1% by mass or more. However, using more than 10% by mass is not preferable because the amount of platinum dissolved in the glass from the platinum container increases.

[0045] Use of a raw material containing chlorine is also effective in reducing moisture in the glass. If a chlorine-containing raw material is included, chlorine will volatilize with the hydroxyl groups when the glass is melted, reducing the moisture in the glass. The proportion of the chlorine-containing raw material is 0.;! To 15% by mass, preferably 0.;! 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 of lowering the glass's 3 / 3-OH value during melting, a method such as bubbling an inert gas (argon gas or nitrogen gas) or a halogen atom-containing gas (fluorine gas or chlorine gas) at the time of melting is available. It is effective. Also It is desirable to select a heating method that reduces the moisture in the atmosphere as much as possible. For example, when glass is melted by burner heating, the amount of moisture in the atmosphere can be reduced by adopting the air combustion method rather than the oxyfuel combustion method. Moreover, if part of the burner heating is switched to electric melting, the amount of moisture in the atmosphere can be further reduced.

[0047] Next, a molten glass is formed to produce a material glass. The material glass molding is not particularly limited. What is necessary is just to shape | mold into the shape convenient for remelting, for example, a mull shape, flake shape, powder shape, a film shape etc.

[0048] In this way, the material glass is once produced. The amount of moisture in the produced material glass is controlled by selecting the glass raw material notch and adjusting the melting conditions. As a result, the / 3-OH of the material glass is preferably 0.35 / mm or less, more preferably 0.25 / mm or less, even more preferably 0.24 / mm or less, especially 0.23 / mm or less. Can be adjusted. By setting the / 3—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 process.

[0049] Subsequently, the material glass is remelted in a platinum container. By remelting, it becomes possible to obtain glass with extremely high homogeneity. In the case of remelting, it is desirable to adjust or select the melting conditions and melting equipment so that the / 3-OH value of the glass after remelting is within the specified range, as described above.

[0050] Thereafter, the molten glass is formed into a desired shape to obtain the target glass.

[0051] The water content of the obtained glass is controlled by selecting a glass raw material batch, adjusting a melting condition, or the like. As a result, the / 3-OH value of the glass finally obtained is 0.30 / mm or less, preferably 0.25 / mm or less, more preferably 0.23 / mm or less, and even more preferably 0.20 / mm. In the following, it becomes possible to adjust especially to below 0.18 / mm. If the / 3—OH value of the glass after remelting is adjusted to 0.30 / mm or less, the amount of platinum contained in the glass will not increase significantly even after remelting.

[0052] The produced glass is not necessarily formed into a shape to be finally used. For example, when it is used as a glass material for mold press molding, it should be molded into a shape suitable for mold press molding.

Example 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, 1;! To 16) and comparative examples (Examples 9 and 10).

[0054] [Table 1]

[0055] [Table 2]

Example 1 Example 2 Example 3 Example 4 Glass composition Glass A Glass B Glass B Glass B Batch weight (g) 300 300 300 300

Soda ash 60% ― ― Monosodium nitrate 40% ― ― Barium raw material

Barium carbonate 1 00% 1 0 (·)% 8 9% 1 00% Barium nitrate-1 1 1%-Boric acid raw material

Anhydrous boric acid 1 00% 1 00% 1 00% 1 00% Orthoboric acid----Material glass

Melting temperature 1 400¾ 1 500 ° C 1 40 O 1 500 ° C Melting time 3 hours 3 hours 3 hours 1 hour β—OH value C / mm) 0. 1 1 0. 1 1 0. 1 5 0. 1 8 Platinum Dissolved amount (p pm) Not measured Not measured Not measured Not measured Platinum count (pieces Zcm ³ ) 9. 1 1 0. 5 1 3. 3 8. 0 Glass sample

Melting temperature 1 300 ° C 1 300 ° C 1 30 O; 1 300¾ Melting time 1 hour 1 hour 1 hour 1 hour β_ΟΗ value (/ "mm) 0. 1 0 0. 1 3 0. 1 3 0. 1 1 Dissolved amount of platinum (p pm) Not measured 1 0. 3 9. 5 Not measured Number of platinum balls (pieces / cm ³ ) 8. 8 1 5. 9 1 8. 5 1 6. 8 Increase in platinum amount

-0.3 5.4 5.2 8.8 (cm ³ ) 3]

Example 5 Example 6 Example 7 Example 8 Glass composition Glass B Glass B Glass B Glass B

/ Tut weight (g) 4000 300 4000 4000

Barium carbonate 89% 100% 100% 100% Barium nitrate 1 1% ― ― ― Boric acid raw material

Anhydrous boric acid 100% ― 100% 100% Orthoboric acid ― 100% ― ― Material glass

Melting temperature 1400 ° C 1400 ° C at 1400 1300¾ Melting time 2 hours 3 hours 3 hours 1 hour β_ΟΗ value (/ mm) 0. 19 0. 23 0. 24 0. 26 Platinum dissolution (p pm) Not measured Not measured Measurement 3.0 Unmeasured platinum count (pieces Zcm ³ ) 0. 4 26. 7 9. 9 17. 0 Glass sample

Melting temperature 1 300. C 130 O: 1300 1 300. C Melting time 1 hour 1 hour 1 hour 1 hour

| 3_ΟΗ value (/ mm) Not measured 0. 14 0. 1 1 0. 1 6 Dissolved platinum (p pm) Not measured Not measured 3.6 Unmeasured platinum count (cm ³ ) 3. 7 37. 2 34. 6 53.4 Addition amount of platinum

3.3 10.5 24.7 36.4 (piece Zcm ³ )]

Example 9 Example 10 Example 1 1 Example 12 Glass composition Glass B Glass B Glass C Glass D Batch weight (g) 4000 4000 500 500

Barium carbonate 100% 100% 90% 90% Barium nitrate ― ― 10% 10% Boric acid raw material

Anhydrous boric acid--100% 100% Orthoboric acid 100% 100%--Material glass

Melting temperature 1 270 1300 ° C 1 30 O: 1 300. C Melting time 1 hour 1 hour 2 hours 2 hours

/ 3—OH value (/ mm) 0. 37 0. 36 0. 18 0. 1 9 Dissolved amount of platinum (P pm) Not measured Not measured Not measured Not measured Platinum book count (piece Zcm ³ ) 10. 5 1 2 8 2. 3 3. 8 Glass sample

Melting temperature 1200 ° C 1 200 ° C 1 250 ° C 1 250t Melting time 1 hour 1 hour 1 hour 1 hour j3—OH value (/ mm) 0. 35 0. 35 0. 13 0. 13 Platinum dissolution (P pm) 5.5 Unmeasured 5.2 Unmeasured platinum book count (cm ³ )>100> 100 3. 2 5. 3 Increase in platinum book

>100> 100 0. 9 1. 5 (pieces / cm ³ ) 5]

Example 1 3 Example 14 Example 15 Example 16 Glass composition Glass E Glass E Glass F Glass F Batch weight (g) 300 300 300 300

Soda ash ― 100% ― 90% Sodium nitrate 100% ― 100% 10%

Barium carbonate 100% 100% 90% 100% Barium sulfate--10% Mono boric acid raw material

Hydrofluoric acid 100% ― 100% ― Orthoboric acid ― 100% One 100% Material glass

Melting temperature 1400 ° C 1400 ° C 1400¾ 1350 ° C Melting time 2 hours 2 hours 2 hours 2 hours β_ΟΗ value (/ mm) 0.21 0.15 0.12 0.18 Platinum dissolution (P pm) Not measured Not measured Not measured Not measured Number (pieces / cm ³ ) 0. 4 1.2 3.2 4.0 Glass sample

Melting temperature 1 300t 130 1300¾ 1300¾ Melting time 1 hour 1 hour 1 hour 1 hour β-one OH value (Zmm) 0.13 0.15 0. 12 0.13 Platinum dissolution (p pm) Not measured Not measured Not measured Not measured Zc m ³ ) 10.1 31.5 5.3 10.5 Increase in platinum

9.7 30.3 2.1 6.5 (piece cm ³ ) Each sample was prepared as follows. First, the oxides, aluminum oxide, boric anhydride, orthoboric acid, barium carbonate, barium nitrate, carbonate so as to have the composition shown in Table 1 (the numerical values shown in Table 1 mean “mass%”). Calcium, strontium carbonate, zinc oxide, lithium carbonate, soda ash, sodium nitrate, lanthanum oxide, and antimony trioxide were prepared. Tables 2-5 show the ratios of the raw materials used for sodium raw materials (soda ash, sodium nitrate), barium raw materials (barium carbonate, barium nitrate), and boric acid raw materials (boric anhydride, orthoboric acid). Next, the raw material batch was placed in a platinum crucible and melted in the air under the conditions shown in Tables 2-5. Thereafter, the molten glass was poured out on a carbon table and formed into a plate shape. The obtained material glass was measured for —OH value and platinum dissolution. Platinum platinum We counted the number of pieces.

[0060] Subsequently, each material glass was pulverized, put into a platinum crucible, and remelted. Thereafter, the molten glass was poured onto a carbon table and formed into a plate shape. About the obtained glass sample, (beta) OH value and platinum dissolution amount were measured. In addition, the number of platinum books was counted and the amount of increase in platinum books before and after remelting was calculated.

[0061] The results of the evaluation are shown in each table. Figure 1 shows the relationship between the / 3 — OH value of the glass material and the increase in the number of platinum particles before and after remelting. Figure 3 shows the relationship between the / 3 — OH value of the glass sample (glass after remelting) and the platinum particles contained in the sample. Figure 2 shows the relationship between the numbers.

[0062] As is clear from the table, glasses A to F have different strengths of glass S. In each case, the lower the / 3 — OH value of the base glass, the lower the increase in platinum black due to remelting. It can be seen that there is a tendency to Similarly, it can be confirmed that the lower the / 3-OH value of the finally obtained glass, the smaller the amount of platinum contained in the glass. Also, as shown in Examples 9 and 10, when the final glass has a / 3—OH value of 0.35 / mm or more, the number of platinum books in the glass sample is 100 m. There were ³ or more. On the other hand, when the / 3—OH value was made to be less than 0.35 / mm, the platinum book in the sample was less than 53.4 / cm ³ .

[0063] Note that the / 3 — OH value was measured as follows. First, the produced glass material 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 the transmission spectrum was measured using FT-IR. Then, it calculated using the following formula.

[0064] β ΟΗ value = (1 / X) log 10 (Τ / Ύ)

1 2

X: Glass wall thickness (mm)

T: Transmittance (%) at reference wavelength 3846cm— ¹ (= 2600nm)

T: hydroxyl absorption near 3600cm- ¹ (= 2800nm) (3400cm- ¹ to 3700cm- ¹

2

Range) (%)

[0065] The amount of dissolved platinum was measured as follows. First, the ground glass sample was decomposed with a mixed acid (HF, HC LO, HNO, HC1) and then evaporated by heating to dryness to obtain a salt. Then dry

4 3

Nitric acid was added to the salt sample and classified, and then analyzed and quantified with an ICP mass spectrometer. [0066] The number of platinum books was determined as follows. First, the produced material glass or glass sample was cut into 35 X 35 XI 5 mm, and the surface was processed into a mirror surface with cerium polishing powder, and then placed on a microscope sample stage. Furthermore, parallel light was incident from the side of the sample, and platinum books were counted and converted to the number per lc m ³ .

Brief Description of Drawings

[0067] Garden 1] Draft the relationship between the 0 OH value of the material glass and the increase in the amount of platinum before and after remelting.

[Figure 2] The relationship between the / 3 OH value of glass after remelting and the number of platinum books contained in the glass

[0068] It will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit, scope and spirit of the invention, which has been described in detail with reference to specific embodiments. This application is based on a Japanese patent application filed on September 4, 2006 (Japanese Patent Application No. 2006-238853), which is incorporated by reference in its entirety. All references cited here are also incorporated in their entirety.

Claims

The scope of the claims

[1] Selection and / or melting conditions of glass raw material batch so that the platinum dissolution amount is 0.1 Ippm or more and less than lOOppm and the β-OH value is 0.07 / mm or more and 0.30 / mm or less. A method for producing glass, characterized by performing the adjustment described above.

[2] A glass raw material batch is melted in a platinum container and molded to produce a raw glass, and then the raw glass is remelted in a platinum container and molded. 3— A glass production method comprising selecting a glass raw material batch and / or adjusting a melting condition so that an OH value is 0 · 30 / mm or less.

[3] The glass raw material batch is selected and / or the melting conditions are adjusted so that the / 3—OH value of the glass after remelting is from 0.07 / mm to 0.30 / mm. The method for producing glass according to claim 2.

[4] 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. Law.

[5] 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 raw material glass is A glass production method comprising selecting a glass raw material batch and / or adjusting a melting condition so as to be 35 / mm or less.

6. The glass raw material notch is selected and / or the melting condition is adjusted so that the amount of platinum dissolved in the material glass is 0 · Ippm or more and less than lOOppm. Any glass manufacturing method.

[7] The method for producing a glass according to any one of [1] to [6], wherein a glass raw material batch containing 0 .;

[8] 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 chlorine-containing raw material is used.

[9] The method for producing a glass according to any one of [1] to [8], wherein the glass obtained is a borosilicate glass, an alkali-containing silicate glass, or an alkali-containing borosilicate glass.

[10] By mass% SiO 5 to 75%, BO 3 to 40%, RO (R: Ca, Sr ,: selected from Ba, Zn 2 to 30%, R '〇 (R': one or more selected from Li, Na, K) 0 to 12%

2

The glass raw material batch prepared so that it may become the glass to contain is used, The manufacturing method of the glass in any one of Claims 1-9 characterized by the above-mentioned.

[11] SiO 25-70% by mass, B O 3 ~ 35%, RO (R: Ca, Sr .: selected from Ba, Zn

2 2 3

5 to 30%, R '〇 (R': one or more selected from Li, Na, K) 0 to 12%

2

The glass raw material batch prepared so that it may become the glass to contain is used. The manufacturing method of the glass in any one of Claims !!-10.

[12] The method for producing glass according to any one of [1] to [11], which is a method for producing optical glass.

[13] The method for producing a glass according to any one of [1] to [12], which is a method for producing a glass material for mold press molding.

[14] A glass produced by the method of any one of claims 1 to 13;

[15] The amount of platinum dissolved is 0.1 Ippm or more and less than lOOppm, and the β-OH value is 0.07.

Glass characterized in that it is not less than / mm and not more than 0.30 / mm.

16. The glass of claim 15, which is a silicate glass.

[17] SiO 5~75% by mass ^{_{0/0, BO 3~40%,}} RO (R: Ca, Sr ,: Ba, selected from Zn

2 2 3

2 to 30%, R '〇 (R': one or more selected from Li, Na, K) 0 to 12%

2

The glass according to claim 15 or 16, characterized in that a glass raw material batch prepared so as to be contained glass is used.

[18] SiO 25-70% by mass, B O 3 ~ 35%, RO (R: Ca, Sr .: selected from Ba, Zn

2 2 3

5 to 30%, R '〇 (R': one or more selected from Li, Na, K) 0 to 12%

2

The glass according to any one of claims 15 to 17, which is contained.

[19] The glass according to any one of [15] to [18], which is an optical glass.

[20] The glass according to any one of claims 15 to 19, which is a glass material for mold press molding.