CN101296872A - Optical glass, manufacturing device of optical glass, and manufacturing method thereof - Google Patents

Abstract

The present invention is used to produce optical glass that is excellent in aging resistance and suppresses the occurrence of platinum nodules. The invention provides an optical glass and a manufacturing method thereof. The optical glass contains 30-70% of SiO ₂ and/or 3-20% of B ₂ O ₃ in terms of mass percentage, and the Pt content is 5ppm or less, in the above optical glass manufacturing method, the gas in the melting device is replaced at a rate of 2 to 20 times per minute based on the volume of the melting furnace, and the non-oxidizing gas is blown into the molten glass.

Description

Optical glass, manufacturing device of optical glass, and manufacturing method thereof

technical field

The present invention relates to an optical glass containing SiO _{2 and} /or B ₂ O ₃ which is excellent _in solarization resistance. _3. Method for producing optical glass, method for producing optical glass containing SiO ₂ and/or B ₂ O ₃ while exhausting gas in a melting device, and method for producing optical glass containing SiO ₂ and/or B ₂ O ₃ device.

Background technique

When producing optical glass, it is important to sufficiently stir the molten material (blank glass or glass) in the cullet process and/or main melting process in which various glass raw materials are melted. As a method of stirring the molten material, there are provided a mechanical stirring method of stirring the molten material with stirring blades and a blowing method using a gas blowing device (for example, refer to Patent Document 1). Here, the blowing method refers to a method in which a gas blowing device is arranged in the melting tank or at the bottom of the melting tank, and bubbles of gas such as oxygen are blown from the gas blowing device so that the liquid moves with the rise of the bubbles, thereby Stir the liquid.

Furthermore, when it is intended to produce highly uniform optical glass with a high yield, it is necessary to prevent contamination (contamination) from melting devices such as the gas blowing device and the melting tank. Therefore, generally, a melting device is used in which at least part or all of the part in contact with the melt is made of platinum or a platinum alloy excellent in heat resistance and corrosion resistance.

Patent Document 1: Japanese Patent Application Publication No. 48-27724

However, when platinum or a platinum alloy is used in a melting tank or a gas blowing device, platinum dioxide (PtO ₂ ) is produced by reacting with oxygen in the air due to the high temperature of the platinum part or part of the platinum alloy part during melting. This _PtO2 turns into a gas and melts into the molten glass from the gas phase through the surface of the molten glass. Furthermore, platinum ions (Pt ⁴⁺ ) also melt into the molten glass from the interface between the molten glass containing SiO ₂ and/or B ₂ O ₃ and platinum or platinum alloy. It is generally believed that there is some correlation between platinum ions and aging phenomena, for example, when Pt ⁴⁺ (including PtO ₂ ) melted into a molten glass containing SiO ₂ and/or B ₂ O ₃ When used in optical glass as a product, the transmittance of the glass containing SiO ₂ and/or B ₂ O ₃ deteriorates or aging phenomenon caused by ultraviolet irradiation may be caused.

The aging phenomenon will degrade the performance of the optical lens containing SiO ₂ and/or B ₂ O ₃ , so whether the aging phenomenon can be suppressed becomes an important factor for using the optical lens. For example, for the optical lens of the i-line stepper, it is required that it will not age due to ultraviolet radiation.

In spite of the problem of aging phenomena as described above, in high-temperature glass production, for the reasons described above, it is unavoidable to use a melting tank or a gas blowing device made of platinum or a platinum alloy. Therefore, an optical glass containing SiO ₂ and/or B ₂ O ₃ excellent in aging resistance is desired.

Contents of the invention

The present invention was developed in view of the above-mentioned problems, and an object thereof is to provide an optical glass containing SiO ₂ and/or B ₂ O ₃ which is excellent in aging resistance, and an optical glass containing SiO 2 and/or B 2 O 3 which is used to manufacture glass excellent in aging resistance. ₂ and/or B ₂ O ₃ optical glass manufacturing method and manufacturing apparatus.

Specifically, the present invention provides the following contents.

(1) An optical glass containing SiO ₂ and/or B ₂ O ₃ , wherein the optical glass has a Pt content (mass basis) of 5 ppm or less.

(2) The optical glass according to (1), characterized in that, in terms of mass percentage, the optical glass contains 30% to 70% of SiO ₂ and/or 3% to 20% of B ₂ O ₃ .

(3) The optical glass according to (1) or (2), wherein

In terms of mass percentage, the optical glass contains the following components:

(a) SiO ₂ : 30-70% and/or

B ₂ O ₃ : 3-20% and/or

PbO: 0~2% and/or

Al ₂ O ₃ : 0~6% and/or

Li ₂ O: 0~5% and/or

CaO: 0~2% and/or

TiO ₂ : 0～0.5% and/or

As ₂ O ₃ : 0~1% and/or

Sb ₂ O ₃ : 0~1% and/or

Na ₂ O: 0～13% and/or

K ₂ O: 0～23% and/or

BaO: 0~42% and/or

ZnO: 0-7%

as well as

(b) The total amount of F in the fluoride obtained by substituting part or all of the oxides is 0-11%.

(4) The optical glass according to any one of (1) to (3), wherein Na ₂ O+K ₂ O+BaO+ZnO is 10 to 45% by mass percent.

(5) The optical glass according to any one of (1) to (4), wherein SrO is 0 to 2% and/or ZrO ₂ is 0 to 2% by mass percentage.

(6) The optical glass according to any one of (1) to (5), wherein CaO+SrO+ZrO ₂ is 0 to 2% by mass percentage.

(7) The optical glass according to any one of (1) to (6), characterized in that, in terms of mass percentage, the optical glass contains 50.5-70% of the SiO ₂ , 3-15% The B ₂ O ₃ , the Al ₂ O ₃ is less than 2.9%, and the Li ₂ O is less than 4.9%.

(8) The optical glass according to any one of (1) to (7), characterized in that, in terms of mass percentage, the optical glass contains 55.35-70% of the SiO ₂ , 2.3% or less of The Al ₂ O ₃ and the Li ₂ O are less than 3%.

(9) The optical glass according to any one of (1) to (8), wherein V, Cr, Mn, Fe, Co, Ni, Cu, Ag, W, Ce, Pr, Nd, Pm , Sm, Eu, Gd, Dy, Ho, Fr, Tm, Yb, and Lu, the total content (mass basis) of each component is 3 ppm or less.

(10) A method for producing optical glass, comprising the steps of "melting a raw material mixture (hereinafter referred to as a batch) to obtain cullet (hereinafter referred to as a cullet process)" and/or "making the cullet A process of melting glass and/or batch materials to obtain glass (hereinafter referred to as the main melting process)", the manufacturing method of the optical glass is characterized in that

The composition of the obtained glass contains SiO ₂ and/or B ₂ O ₃ , and

A non-oxidizing gas is blown into the melt in the cullet process and/or the main melting process.

(11) The method for producing optical glass according to (10), wherein the non-oxidizing gas is blown to a depth of 100 mm or more from the liquid surface of the melt.

(12) The method for producing optical glass according to (10) or (11), wherein the non-oxidizing gas is blown at a supply rate of 0.002 to 0.05 liter/minute per liter of glass volume.

(13) The method for producing optical glass according to any one of (10) to (12), wherein the non-oxidizing gas is He, Ne, Ar, Kr, Xe, N ₂ , H ₂ , CO or a variety of mixed gases of these gases.

(14) A method for producing optical glass, comprising the steps of "melting a raw material mixture (hereinafter referred to as a batch) to obtain cullet (hereinafter referred to as a cullet process)" and/or "making the obtained The process of obtaining glass by melting the cullet and/or batch material (hereinafter referred to as the main melting process)", the manufacturing method of the optical glass is characterized in that

The composition of the obtained glass contains SiO ₂ and/or B ₂ O ₃ series, and

The gas in the space in the melting device in the cullet process and/or the main melting process is exhausted.

(15) The method for producing optical glass according to (14), wherein in the cullet forming step and/or the main melting step, the batch material and/or the cullet are melted, At the same time, the gas in the space in the melting device is exhausted.

(16) The method for producing optical glass according to (14) or (15), wherein the melting device is replaced at a rate of 2 to 20 times per minute based on the volume of the space in the melting device. gas inside.

(17) A manufacturing apparatus for optical glass containing at least SiO ₂ and/or B ₂ O ₃ , characterized in that the optical glass manufacturing apparatus is characterized in that

Including: a batch material melting device for melting batch materials to obtain cullet and/or a formal melting device for melting the cullet or the batch material to obtain glass melts, and a non-oxidizing gas bubbling device is arranged on the The raw material mixture melting device and/or the cullet melting device.

(18) A manufacturing device for optical glass containing at least SiO ₂ and/or B ₂ O ₃ , the manufacturing device for optical glass is characterized in that

Comprising: a melting tank for melting batch materials or cullets to obtain melts; a furnace body covering the periphery of the melting tank and having an opening for feeding the batch materials or cullets; and an exhaust mechanism , which is arranged or communicated near the opening, and is used to discharge the gas generated by the molten material in the melting tank.

The effect of the invention

According to the present invention, an optical glass containing SiO ₂ and/or B ₂ O ₃ excellent in aging resistance can be provided.

According to the method for producing optical glass of the present invention, it is possible to provide a method for producing optical glass capable of suppressing aging phenomenon and occurrence of platinum nodules in a melting process using a melting device using platinum or a platinum alloy as a material.

As a result, optical glass with "good initial light transmittance" and/or "less deterioration in light transmittance after light irradiation" can be obtained, which is used in the semiconductor industry (especially for steppers), bioengineering, etc. Optical glass used in various fields such as medical and medical.

Description of drawings

Fig. 1(A) is a plan view of a raw material melting device for melting glass raw materials. Fig. 1(B) is a plan view of an actual melting device for melting cullet.

Fig. 2(A) is a cross-sectional view along IV-IV of Fig. 1(A) of a batch material melting device using a gas blowing device according to an embodiment of the present invention. Fig. 2(B) is a cross-sectional view along line IV-IV of Fig. 1(B) of the main melting device using the gas blowing device according to the embodiment of the present invention.

3 is a graph showing i-ray irradiation time and the deterioration rate of the transmittance of optical glass.

Explanation of symbols

100 batch material melting device

200 Formal melting device

102, 202 melting furnace

106, 206 gas blowing device

110, 210 ventilation device

112, 212 conical part

114, 214 suction port

116, 216 exhaust pipe

121, 221 melting tank

122, 222 furnace body

126, 226 openings

203 outlet

204 delivery pipe

A batch melt

D formal melt

Detailed ways

Hereinafter, each embodiment of this invention is demonstrated based on drawing. In addition, in the description of the following embodiments, the same components are given the same reference numerals, and their descriptions are omitted or simplified.

In addition, the present invention is not limited to the embodiments described below, and modifications, improvements, and the like within the range that can achieve the object of the present invention belong to the present invention.

composition of glass

The composition range of each component constituting the optical glass of the present invention will be described below. Each component is expressed in mass percentage. In addition, all the glass compositions expressed by mass percentage in the specification of this application are expressed by mass percentage based on oxides. Here, "based on oxides" means that when oxides, nitrates, etc., which are used as raw materials for the glass constituents of the present invention, are all decomposed into oxides during melting, the mass sum of the generated oxides is set as It is 100% by mass, and then expresses the composition of each component contained in the glass:.

First, the composition range in which optical glass containing SiO ₂ and/or B ₂ O ₃ , especially optical glass having a SiO ₂ -B ₂ O ₃ component, excellent in aging resistance can be produced in the present invention will be described.

The reason why each component is limited to the said composition range is as follows.

For optical glass containing SiO ₂ , SiO ₂ is a useful component in glass formation. However, when the weight percentage of _SiO2 is less than 30%, it is not preferable, because it tends to require a large amount of components such as _B2O3 or _BaO , and the refractive index is also likely to become high, or the chemical properties are likely to deteriorate. . In addition, when SiO ₂ exceeds 70%, the viscosity of the glass tends to become high, and as a result, it tends to be difficult to obtain a glass with a uniform texture. Therefore, the lower limit of SiO ₂ is preferably 50.5% or more, more preferably 53.0% or more, and most preferably 55.35% or more, considering factors such as refractive index, deterioration characteristics of chemical properties, and glass viscosity. Also, the upper limit of _SiO2 is preferably 70% or less, more preferably 65% or less, and most preferably 61% or less.

In optical glass containing B ₂ O ₃ , B ₂ O ₃ is a glass-forming oxide like SiO ₂ , and is effective in reducing dispersion of glass or adjusting viscosity. However, it is not preferable when _B2O3 is less than 3% or more than 20%, because if _B2O3 is less than 3%, the effect is likely to be insufficient, and if _it exceeds 20% _, the chemical properties are likely to deteriorate. . Further considering factors such as low dispersion of glass, viscosity, and deterioration of chemical properties, B ₂ O ₃ is preferably 3% or more and 20% or less. Therefore, the upper limit of B ₂ O ₃ is preferably 20% or less, more preferably 17% or less, and most preferably 15% or less. Also, the lower limit of B ₂ O ₃ is preferably 3% or more, more preferably 5% or more, and most preferably 6% or more.

Al ₂ O ₃ is effective in improving the chemical durability of glass and adjusting viscosity or refractive index. However, when _Al2O3 exceeds 6%, the viscosity of glass tends _to become high. Furthermore, considering the chemical durability, viscosity, and refractive index of the glass, Al ₂ O ₃ is more preferably 2.9% or less, most preferably 2.3% or less.

Li ₂ O has an effect of promoting the melting of glass raw materials, and is an effective component because it is less likely to cause a decrease in the refractive index than other alkali metal oxides. However, when Li ₂ O exceeds 5%, it is not preferable because the devitrification of the glass tends to increase in this case. Furthermore, taking into account factors such as viscosity, refractive index, and deterioration of chemical properties, Li ₂ O is more preferably 4.9% or less, most preferably 3% or less.

Na ₂ O and K ₂ O are effective in accelerating melting of glass raw materials, and stable glass can be produced even if Na ₂ O and K ₂ O are contained in large amounts in glass. However, it is not preferable when the amounts of Na ₂ O and K ₂ O exceed 13% and 23% respectively, because chemical properties are easily deteriorated at this time. The upper limit of Na ₂ O is preferably 13% or less, more preferably 10% or less, and most preferably 7% or less. Furthermore, the upper limit of K ₂ O is preferably 23% or less, more preferably 20% or less.

BaO does not excessively increase the dispersion of the glass (does not excessively reduce the Abbe number), but can increase the refractive index, and can obtain a stable glass with high devitrification resistance in a wide composition range. However, when BaO exceeds 42%, the chemical durability of glass tends to deteriorate extremely. Therefore, the upper limit of BaO is preferably 42% or less, more preferably 25% or less, and most preferably 18% or less.

ZnO is a component effective in increasing the refractive index, adjusting viscosity, improving devitrification resistance, and the like. However, when ZnO exceeds 7%, it is not preferable because in this case, the transmittance in the short-wavelength region decreases. Therefore, the upper limit of ZnO is preferably 7% or less, more preferably 3% or less, and most preferably 1% or less.

In addition, in order to obtain a glass that is stable, excellent in chemical properties, and has good transmittance up to the short wavelength region, the range of the total amount of one or more components of _Na2O , _K2O , BaO, and ZnO (% ) is preferably 45% or less, more preferably 40% or less, most preferably 35% or less. Also, the lower limit is preferably 10% or more, more preferably 13% or more, and most preferably 15% or more.

For optical glass containing SiO ₂ and/or B ₂ O ₃ , especially for SiO ₂ -B ₂ O ₃ -alkali metal oxide and/or alkaline earth metal oxide glass, PbO and TiO ₂ play an important role in preventing aging. phenomenon is effective. However, if the content of the above-mentioned components is more than necessary, it is likely to cause deterioration of the light transmittance in the short-wavelength region. Therefore, the upper limits of the content of the above-mentioned components are preferably 2% or less and 1.0% or less, and more preferably 1%. Below and below 0.1%.

As ₂ O ₃ and Sb ₂ O ₃ have effects as glass clarification aids and can be added arbitrarily, but in order to obtain the above effects, it is sufficient to add 1% or less of each.

Fluorine can be added arbitrarily as a fluoride substituted for part or all of one or two or more of the above-mentioned oxides, and is effective in adjusting the refractive index and viscosity. However, when the total amount of the fluoride exceeds 11%, it is not preferable because the glass tends to become opalescent or the refractive index tends to be too small, and fluorine volatilizes excessively during melting, making it difficult to manufacture a uniform glass. . The upper limit of the total amount of fluoride is preferably 11% or less, more preferably 9.5% or less.

In addition, in addition to the above-mentioned components, in order to adjust the refractive index and improve the chemical properties of the glass, optional components such as CaO, SrO and ZrO ₂ may be added in an amount not exceeding 2%. Furthermore, when these components are added, the total amount of one or two or more selected from CaO, SrO, and ZrO ₂ is preferably not more than 2%, more preferably 1% or less.

Moreover, transition metals other than Ti, such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, W, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Dy, Ho, Fr, Tm, Yb The total content of each component of Lu is preferably 3 ppm or less. The above-mentioned components contained as impurities have a large absorption coefficient, and even if mixed in a small amount, the transmittance will be deteriorated.

In order to prevent aging phenomenon, the Pt content of the optical glass of the present invention is preferably 5 ppm or less. More preferably 1 ppm or less, more preferably 0.5 ppm or less, most preferably 0.2 ppm or less.

Batch melting device, cullet vitrification process

Hereinafter, a batch melting device and a cullet process for producing glass with a low platinum content and good aging resistance will be described in detail.

As shown in Fig. 1(A) and Fig. 2(A), the batch material melting device 100 used in the cullet vitrification process includes: a melting furnace 102, which is used to melt the batch material to obtain the batch material melt A; and gas blowing Device 106, blowing gas into the batch melt A. Furthermore, the melting furnace 102 includes: a melting tank 121 serving as a container when the batch material is melted; a furnace body 122 covering the periphery of the melting tank 121; and a heating device (not shown).

For the melting tank 121, considering factors such as the melting of the batch material melt A, heat resistance required for clarification, corrosion resistance, and less influence on the quality of the batch material melt A, it is The part in contact with molten material A is, for example, a melting tank made of quartz, platinum (Pt) or a platinum alloy (Pt alloy), more preferably a melting tank 121 made of platinum or a platinum alloy.

The furnace body 122 covers the periphery of the melting tank 121 and is formed of heat-resistant materials such as refractory bricks. On the upper portion of the furnace body 122, an opening 126 for injecting glass raw materials into the melting tank 121 is formed. Furthermore, the opening 126 serves as an inlet for introducing the gas remaining in the batch melt A in the melting tank 121 to a discharge device (not shown) connected to discharge the gas remaining from the inside of the furnace body 122 . Gas ventilation device 110 .

The gas blowing device 106 is inserted into the melting tank 121 through the opening 126 . That is, the opening 126 also serves as an insertion hole for the gas blowing device 106 for blowing gas into the melt. In order to sufficiently stir the batch melt A, the structure of the gas blowing device 106 is a well-known structure capable of generating large bubbles as much as possible. For this gas blowing device 106, considering factors such as their heat resistance, corrosion resistance to the batch material melt A, and less influence on the quality of the batch material melt A, it is preferable, for example, to be combined with the batch material A The part in contact with the molten material A is a gas blowing device made of quartz, platinum or a platinum alloy, more preferably a gas blowing device made of platinum or a platinum alloy.

When platinum or a platinum alloy is used in the part of the melting tank 121 and other components constituting the batch material melting device 100 or the gas blowing device 106, which is in contact with the batch material melt A, _PtO2 is generated because oxygen reacts with the platinum or platinum alloy. Therefore, as the gas used for blowing by the gas blowing device 106, a non-oxidizing gas is preferable. Examples of non-oxidizing gases include gases with an oxygen partial pressure of 1% or less, preferably 0.01% or less, more preferably 0.0001% or less, preferably helium (He), neon (Ne), argon (Ar), and krypton Neutral gases such as (Kr), xenon (Xe) or nitrogen (N ₂ ), or reducing gases such as carbon monoxide (CO) or/and hydrogen (H ₂ ), or a mixture of two or more selected from the above gases gas.

The depth at which the non-oxidizing gas is blown into the batch material melt A using the gas blowing device 106 can be set arbitrarily, but it is preferable to inject the non-oxidizing gas into the batch material melt A at a depth of 100 mm or more from the liquid surface of the batch material melt A. Blow in non-oxidizing gas.

In addition, the ventilation device 110 is installed on the upper part of the melting furnace 102 . The ventilator 110 includes: a conical portion 112 formed with a suction port 114 whose opening surface shape is substantially the same as that of the opening 126 ; and an exhaust pipe 116 connected to the conical portion 112 . In addition, the ventilation device 110 is an example of an exhaust mechanism for exhausting the gas generated from the batch melt A in the melting tank 121 .

The conical portion 112 has a conical shape, that is, gradually becomes thinner as it goes upward from the suction port 114 .

The gas in the batch melting device 100 is discharged at a rate of 2 to 20 times/min using the ventilation device 110 based on the space volume of the melting furnace 102 during melting (batch melting process).

The exhaust pipe 116 is formed to be divided into two from the uppermost part of the conical part 112 to the direction perpendicular to the gas blowing device 106, and only one of the left and right sides (the right side in this embodiment) is exhausted. The pipe 116, whose direction is changed to be parallel to the direction of the gas blowing device 106, that is, the anti-gravity direction, is extended, and the other side (the left side in this embodiment) exhaust pipe 116 is closed halfway.

In addition, in the ventilator 110, the air pressure in the melting space above the batch melt A is controlled by suctioning the opening on the opposite side to the conical portion 112 by a suction pump as an example of a suction mechanism (suction device). 0.1kPa to 100.0kPa (1hPa to 1000hPa), and at the same time, the gas present in the space above the batch melt A in the batch melting device 100 is discharged. Further, in this embodiment, only one of the left and right sides (in this embodiment, the right side) exhaust pipe 116 is extended and connected to the suction mechanism, but as long as the air pressure above the batch material melt A is controlled to Within the above range, the exhaust pipe on the left side can also be extended to connect to other melting devices.

In this way, the pressure in the space above the batch material melt A is controlled to be approximately the same as the atmospheric pressure or the negative pressure side lower than the atmospheric pressure, and at the same time, the gas present in the space above the batch material melt A in the melting tank 121 is released from the furnace body. 122 inside is discharged toward the suction port 114 of the ventilator 110 through the opening 126 .

In addition, as the gas remaining in the batch material melt A, there are oxygen which is an oxidizing gas, the gas blown in when blowing with the gas blowing device 106, and _PtO2 produced by the reaction between oxygen and platinum or a platinum alloy. wait.

Main melting device, main melting process

Hereinafter, the main melting device and the main melting process for producing glass with a low platinum content and good aging resistance will be described in detail.

As shown in Figure 1 (B) and Figure 2 (B), the formal melting device 200 used in the formal melting process includes: a melting furnace 202, which is used to melt the batch material to obtain a formal melt, or to make the broken glass chemically The cullet obtained in the procedure is melted to obtain the main molten material D; the discharge port 203 for discharging the main molten material D; the delivery pipe 204 as a path (conduit) of the main molten material D from the melting furnace 202 to the subsequent process; gas blowing The device 206 blows gas into the main melt D;

The melting furnace 202 includes: a melting tank 221 serving as a container for cullet melting; a furnace body 222 made of heat-resistant materials such as refractory bricks covering the periphery of the melting tank 221; and a heating device (not shown).

For the melting tank 221, considering factors such as the melting of the official melt D, the heat resistance required for clarification, the erosion resistance, and the less impact on the quality of the official melt D, it is preferred that at least the same as the official melt D The portion in contact with D is, for example, a melting tank made of quartz, platinum or a platinum alloy, more preferably a melting tank made of platinum or a platinum alloy.

The furnace body 222 covers the periphery of the melting tank 221 and is made of heat-resistant materials such as refractory bricks. An opening 226 for feeding cullet into the melting tank 221 is formed on the upper portion of the furnace body 222 . And this opening 226 serves as an inlet for introducing the gas remaining in the main melt D in the melting tank 221 to the suction port 214 for exhausting the remaining gas from the inside of the furnace body 222 .

On the delivery pipe 204, a heating device (not shown) is provided. The temperature of the conveying pipe 204 is controlled by the heating device, thereby controlling the viscosity of the formal melt D in the conveying pipe 204 and controlling the flow rate of the formal melt D in the conveying pipe 204 . Furthermore, as described above, the transfer pipe 204 serves as a conduit for the main melt D from the main melting step to the subsequent steps (clarification step, stirring step, and slow cooling step).

The gas blowing device 206 is inserted into the melting tank 221 through the opening 226 . That is, the opening also serves as an insertion hole for a gas blowing device for blowing gas into the melt. In order to sufficiently stir the main melt D, the structure of the gas blowing device 206 is a well-known structure capable of generating large bubbles as much as possible. For this gas blowing device 206, considering factors such as their heat resistance, corrosion resistance to the official melt D, and less influence on the quality of the official melt D, it is preferable, for example, at least with the official melt The portion in contact with D is a gas blowing device made of quartz, platinum or a platinum alloy, and a gas blowing device made of platinum or a platinum alloy is particularly preferable.

The gas used for blowing by the gas blowing device 206 can be set arbitrarily. However, when the melting tank 221, the conveying pipe 204, etc. constitute the components of the main melting device 200 or the gas blowing device 206, the part in contact with the main molten material D is platinum or platinum alloy, because oxygen will react with platinum or platinum alloy. Since PtO ₂ is generated, the gas used for blowing with the gas blowing device 206 is preferably a non-oxidizing gas. Examples of non-oxidizing gases include gases with an oxygen partial pressure of 1% or less, preferably 0.1% or less, more preferably 0.01% or less, preferably helium (He), neon (Ne), argon (Ar), and krypton (Kr), neutral gas such as xenon (Xe) or nitrogen (N ₂ ), or reducing gas such as carbon monoxide (CO) or hydrogen (H ₂ ), or a mixed gas of two or more selected from the above gases.

The depth at which the non-oxidizing gas is blown into the main molten material D using the gas blowing device 206 can be set arbitrarily, but it is preferable to blow into the cullet molten material D at a depth of 100 mm or more from the liquid surface of the main molten material D. into the non-oxidizing gas.

Ventilation device 210 is installed on the upper portion of melting furnace 202 . The ventilator 210 includes: a conical portion 212 formed with a suction port 214 whose opening surface shape is substantially the same as that of the opening 226 ; and an exhaust pipe 216 connected to the conical portion 212 . In addition, the ventilation device 210 is an example of an exhaust mechanism for exhausting the gas generated from the molten cullet in the melting tank 221 .

The conical portion 212 has a conical shape, that is, gradually becomes thinner as it goes upward from the suction port 214 .

The gas in the main melting device 200 is discharged at a rate of 2 to 20 times/min using the ventilation device 210 based on the space volume of the melting furnace 202 during melting (the main melting process).

The exhaust pipe 216 is formed to be divided into two from the uppermost part of the conical part 212 to the direction perpendicular to the gas blowing device 206, and only one of the left and right sides (in this embodiment, the right side) is exhausted. The pipe 216, whose direction is changed to be parallel to the direction of the gas blowing device 206, that is, the anti-gravity direction, is extended, and the other side (the left side in this embodiment) exhaust pipe 216 is closed halfway.

In addition, in the ventilator 210, the air pressure in the melting space above the main molten material D is controlled by sucking the opening portion on the opposite side to the conical portion 212 with a suction pump as an example of a suction mechanism (suction device). 0.1kPa to 100.0kPa (1hPa to 1000hPa), while discharging the gas existing in the upper space of the main melt D in the main melting device 200 . Further, in this embodiment, only one of the left and right sides (in this embodiment, the right side) exhaust pipe 216 is extended and connected to the suction mechanism, but as long as the air pressure in the space above the actual molten material D is controlled at Within the stated range, then the exhaust pipe on the left side can also be extended to connect to other melting devices.

In this way, the air pressure in the upper space of the actual molten material D is controlled to be substantially the same as the atmospheric pressure or lower than the negative pressure side of the atmospheric pressure, and at the same time, the gas existing in the upper space of the cullet molten material D in the melting tank 221 is released from the furnace body 222 The inside is discharged toward the suction port 214 of the ventilator 210 through the opening 226 .

In addition, as the remaining gas in the main molten material D, there are oxygen which is an oxidizing gas, the gas blown in when blowing with the gas blowing device 206, and _PtO2 produced by the reaction between oxygen and platinum or a platinum alloy, etc. .

On the delivery pipe 204, a heating device (not shown) is provided. The temperature of the conveying pipe 204 is controlled by the heating device, thereby controlling the viscosity of the formal melt D in the conveying pipe 204 , and as a result, the flow rate of the formal melt D in the conveying pipe 204 is controlled. Furthermore, as described above, the transfer pipe 204 serves as a conduit for the main melt D from the main melting step to the subsequent steps (clarification step, stirring step, and slow cooling step).

Furthermore, in this embodiment, the gas blowing devices 106, 206 are respectively inserted into the melting tanks 121, 221 through the openings 126, 226 on the upper part of the furnace body 122, 222, but it is not limited thereto. The blowing device 106, 206 may penetrate the side part or the bottom of the melting tank 121, 221, and blow the gas into the batch melt A or the main melt D from the side part or the bottom.

In addition, in the present embodiment, in the two melting steps of the culletization step and the main melting step, the gas blowing devices 106 and 206 are used to blow the gas into the batch melt A and the main melt D, respectively. The gas may be blown only in either the cullet process or the main melting process. And, in the process of not performing gas blowing, it is also possible to prepare a stirrer equipped with stirring blades for stirring the melt (for example, the batch melt A) in the melting tank (for example, melting tank 121 or melting tank 221). or formal melt D). The shape of this stirring blade is not specifically limited, For example, the stirring blade of a well-known shape and structure, such as a spiral shape, can be used.

Furthermore, in the present embodiment, the exhaust mechanism is provided in the batch material melting process and the main melting process, but the exhaust mechanism may be provided in either process.

In addition, in this embodiment, only the ventilator 210 as an example of the discharge mechanism is provided in the main melting device 200 installed in the main melting process, but the ventilator 210 may be omitted as necessary. Furthermore, the ventilator 110 as a discharge mechanism may also be provided in the batch melting device 100 installed in the cullet process. In addition, when the ventilator 110 as a discharge mechanism is provided in the batch material melting apparatus 100, the ventilator 210 may be omitted in the main melting apparatus 200 as needed.

As long as the ventilators 110 and 210 have the function of discharging the gas present in the upper space of the batch melt A and the cullet melt D, well-known ventilators having various shapes and structures can be used.

Moreover, for the delivery pipes 204 and the like constituting the main melting device 200, considering factors such as their heat resistance, corrosion resistance to glass, and less influence on the quality of the main molten product D, it is preferable that at least The part in contact with the main melt D is made of platinum or a platinum alloy, but it is not necessarily limited to these materials.

Moreover, when the flow rate of the molten material is controlled by parameters other than the viscosity of the molten material, such as the pressure in the melting tank 221 , it is not necessarily necessary to install a heating device (not shown) on the conveying pipe 204 .

The heating device can use a well-known heating device, such as an electric heater, an electric heater, an electric heating element, a high-frequency induction heating device, or a heating device that uses a burner or the like to heat through combustion of gas, etc., and further, transport The tube 204 can preferably be heated by direct energization, but it is not necessarily limited thereto.

Manufacturing method of optical glass

Next, the manufacturing method which manufactures the optical glass of this invention using the said melting apparatus and manufacturing method is demonstrated using FIG.2(A) and FIG.2(B).

First, as shown in FIG. 2A , in terms of mass percentage, a batch capable of producing optical glass that is formulated to contain 30% to 70% of SiO ₂ and/or 3% to 20% of B ₂ O ₃ is prepared. The material is put into the melting tank 121 of the batch material melting device 100 and melted. At this time, a non-oxidizing gas is blown into the batch melt A obtained by melting (roughly melting) the glass raw material using the gas blowing device 106 . This gas blowing is carried out as follows: at a depth of 100 mm or more from the liquid surface of the batch molten material A in the melting tank 121, the volume of the batch molten material A is supplied at a rate of 0.002 to 0.05 liters per minute. Speed blowing non-oxidizing gas (crushed vitrification process). The obtained batch melt A was cast outside the furnace and recovered as cullet.

Next, as shown in FIG. 2(B), the recovered cullet is put into the melting tank 221 of the main melting device 200 and melted. At this time, a non-oxidizing gas (for example, argon) is blown into the main melt D obtained by melting (mainly melting) the cullet using the gas blowing device 206 . This gas blowing is carried out by blowing gas at a supply rate of 0.002 to 0.05 liter/min per 1 liter of the volume of the main melt D at a depth of 100 mm or more from the liquid surface of the main melt D in the melting tank 221. into the non-oxidizing gas.

Then, in the step of melting the cullet, the gas above the main melt D is sucked by a suction pump as an example of a suction mechanism (suction device) from the ventilation device 210 (main melting step). At this time, if the suction pump is controlled so that the air pressure above the main melt D is 0.1 kPa to 100.0 kPa (1 hPa to 1000 hPa), the gas above the main melt D can be discharged well. Furthermore, it is preferable to replace the gas in the main melting device 200 at a rate of 2 to 20 times/min based on the space volume during melting in the melting furnace 202 . The obtained main melt D is transferred from the main melting step to subsequent steps (clarification step, stirring step, cold preservation step), and optical glass is produced in the subsequent step.

In addition, in the present embodiment, after the glass raw material is melted in the raw material melting step, it is rapidly cooled to produce solidified cullet, and the produced cullet is put into the melting tank 221 to obtain the main melt D, and then The molten material is then continuously supplied to the subsequent process, but the actual melting process may also be carried out in a batch mode instead of a continuous mode.

Hereinafter, the present invention will be described in more detail using examples and comparative examples, but the present invention is not limited to the following examples.

Example

The optical glass produced by the production method of the present invention is used as the optical glass of the example, and the optical glass produced by other methods is used as the optical glass of the comparative example, and these glasses are irradiated with the i-line (365nm) of the ultra-high pressure mercury lamp. , and measure the change in transmittance at this time.

Example 1

The raw materials for optical glass (glass raw materials) were weighed according to the composition ratio shown in Table 1, and these were mixed.

Table 1

No. Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 comparative example SiO ₂ 63 60 60 60 58 51 60 B ₂ O ₃ 8 15 11 6 10 17 15 Al ₂ O ₃ 1 0 0 0 2 0 0 K ₂ O 20 15 18 14 6 10 15 F 8 10 5 0 0 0 10 BaO 0 0 3 10 15 10 0 PbO 0 0 1 1 0 0 0 Li ₂ O 0 0 0 1 0 0 0 Na ₂ O 0 0 1 1 5 7 0 ZnO 0 0 1 7 3 5 0 As ₂ O ₃ 0.1 0.01 0.01 0.01 0.01 0.01 0 Sb ₂ O ₃ 0 0 0 0 0 0 0.01 Total 100.1 100.01 100.01 100.01 99.01 100.01 100.01 advocating Ar Ar Ar Ar Ar Ar O ₂ Pt content (ppm) 0.10 0.12 0.14 0.21 0.26 0.29 0.70 Amount of transition metals (ppm) 2.6 2.4 2.3 2.9 2.5 2.8 3.1 Transmittance deterioration rate (%) (500hr irradiation) -0.098 -0.084 -0.100 -0.110 -0.138 -0.157 -0.214

Subsequently, the glass raw material was put into the melting tank 121 of the batch material melting apparatus 100, and the cullet process was performed at 1300 degreeC for 14 hours. At this time, without gas blowing, the batch melt was cooled and recovered as cullet. The recovered cullet was put into the melting tank 221 of the main melting device 200, and melting was performed at 1150° C. for 15 hours. At this time, argon gas was blown into the main melt D obtained by melting (main melting) the cullet using the gas blowing device 206 . This blowing was performed at a gas supply rate of 0.024 liter/minute per liter of glass at a depth of 500 mm from the liquid surface to be blown. In addition, in this melting step, the space above the main melt D is reduced in pressure compared to the atmospheric pressure (the pressure in the space above the main melt D is 0.3 kPa), thereby making the upper space of the main melt D The gas present in the inside is sucked by the ventilation device 210 and discharged into the atmosphere (main melting process). The obtained full-scale melt D was transferred to subsequent steps (clarification step, stirring step, and cold preservation step) to manufacture the optical glass of this example.

comparative example

The glass raw material of the optical glass of this comparative example was weighed by the same composition ratio as Example 1, and they were mixed. Subsequently, this glass raw material was put into the melting tank 121 of the raw material melting apparatus 100, and the cullet process was performed at 1300 degreeC for 14 hours. At this time, without gas blowing, the batch melt was cooled and recovered as cullet. The recovered cullet was put into the melting tank 221 of the main melting device 200, and melting was performed at 1150° C. for 15 hours. At this time, "oxygen" is blown into the main melt D obtained by melting (main melting) the cullet using the gas blowing device 206 . This blowing was performed at a gas supply rate of 0.024 liter/minute per liter of glass at a depth of 500 mm from the liquid surface to be blown. In addition, in the process of melting this glass gob, gas is not exhausted from the upper space of the main melt D (main melting process). The obtained main molten material D was transferred to the subsequent process (clarification process, stirring process, cold storage process), and the optical glass of this comparative example was manufactured.

Next, the optical glass of the example and the optical glass of the comparative example were irradiated with i-rays (365 nm) under the condition of 2.5 W/cm ² , and changes in transmittance at that time were measured. In addition, the transmittance is the transmittance of light rays with a wavelength of 365 nm measured using U-4000 (manufactured by Hitachi, Ltd.).

FIG. 3 shows changes in transmittance when i-rays (365 nm) are irradiated to the optical glass of the example and the optical glass of the comparative example. As shown in FIG. 3 , immediately after the irradiation, the deterioration rate of the optical glass of the comparative example was larger than that of the optical glass of the example. And, this tendency becomes remarkable as the irradiation time elapses. In this way, an optical glass with excellent aging resistance can be provided by providing an air duct to exhaust the gas in the space above the cullet melt, and using a gas blowing device to blow gas into the batch melt and/or the main melt.

In addition, Table 1 shows the composition of the optical glass according to the example of the present invention, the amount of deterioration of the transmittance under i-ray irradiation (500 hours), and the Pt content.

As shown in Table 1, it can be seen that the Pt content of Examples 1 to 6 is smaller than that of the comparative example, and the aging resistance is excellent.

Claims (18)

1, a kind of opticglass, it contains SiO ₂And/or B ₂O ₃, this opticglass is characterised in that,

Pt content (quality criteria) wherein is below the 5ppm.

2, opticglass according to claim 1 is characterized in that,

Come in mass percent, described opticglass contains the SiO more than 30%, below 70% ₂And/or 3% above, B below 20% ₂O ₃

3, opticglass according to claim 1 and 2 is characterized in that,

Come in mass percent, described opticglass contains following compositions:

(a) SiO ₂: 30～70% and/or

B ₂O ₃: 3～20% and/or

PbO:0～2% and/or

Al ₂O ₃: 0～6% and/or

Li ₂O:0～5% and/or

CaO:0～2% and/or

TiO ₂: 0～0.5% and/or

As ₂O ₃: 0～1% and/or

Sb ₂O ₃: 0～1% and/or

Na ₂O:0～13% and/or

K ₂O:0～23% and/or

BaO:0～42% and/or

ZnO：0～7％

And

(b) the total amount of part or all of described oxide compound F in the fluorochemical of displacement gained is 0～11%.

4, according to the described opticglass of arbitrary claim in the claim 1 to 3, it is characterized in that,

Come Na in mass percent ₂O+K ₂O+BaO+ZnO is 10～45%.

5, according to the described opticglass of arbitrary claim in the claim 1 to 4, it is characterized in that,

Come in mass percent, SrO is 0～2% and/or ZrO ₂Be 0～2%.

6, according to the described opticglass of arbitrary claim in the claim 1 to 5, it is characterized in that,

Come CaO+SrO+ZrO in mass percent ₂Be 0～2%.

7, according to the described opticglass of arbitrary claim in the claim 1 to 6, it is characterized in that,

Come in mass percent, described opticglass contains 50.5～70% described SiO ₂, 3～15% described B ₂O ₃, the described Al below 2.9% ₂O ₃And the described Li below 4.9% ₂O.

8, according to the described opticglass of arbitrary claim in the claim 1 to 7, it is characterized in that,

Come in mass percent, described opticglass contains 55.35～70% described SiO ₂, the described A1 below 2.3% ₂O ₃And the described Li below 3% ₂O.

9, according to the described opticglass of arbitrary claim in the claim 1 to 8, it is characterized in that,

The total content (quality criteria) of V, Cr, Mn, Fe, Co, Ni, Cu, Ag, W, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Dy, Ho, Fr, Tm, Yb, each composition of Lu is below the 3ppm.

10, a kind of manufacture method of opticglass, it comprises following operation: " with raw mix (below be called batch of material) fusion and obtain the operation (below be called glass cullet chemical industry preface) of glass cullet " and/or " with glass cullet and/or batch of material fusion and obtain the operation (below be called formal fusion operation) of glass ", the manufacture method of described opticglass is characterised in that

Contain SiO in the composition of the glass that is obtained ₂And/or B ₂O ₃, and

In the melts of described glass cullet chemical industry preface and/or described formal fusion operation, advertise non-oxidizing gas.

11, the manufacture method of opticglass according to claim 10 is characterized in that,

Described non-oxidizing gas is blown into apart from the degree of depth more than the liquid level 100mm of described melts.

12, according to the manufacture method of claim 10 or 11 described opticglass, it is characterized in that,

Be blown into described non-oxidizing gas at per 1 liter of glass volume with 0.002～0.05 liter/minute feed speed.

13, according to the manufacture method of the described opticglass of arbitrary claim in the claim 10 to 12, it is characterized in that,

Described non-oxidizing gas is He, Ne, Ar, Kr, Xe, N ₂, H ₂, CO or these gases various mixed gases.

14, a kind of manufacture method of opticglass, it comprises following operation: will " raw mix (below be called batch of material) fusion and obtain the operation (below be called glass cullet chemical industry preface) of glass cullet " and/or " described glass cullet and/or batch of material fusion being obtained the operation (below be called formal fusion operation) of glass ", the manufacture method of described opticglass is characterised in that

Contain SiO in the composition of the glass that is obtained ₂And/or B ₂O ₃System, and

Gas in the space in the melting plant in described glass cullet chemical industry preface and/or the described formal fusion operation is discharged.

15, the manufacture method of opticglass according to claim 14 is characterized in that,

In described glass cullet chemical industry preface and/or described formal fusion operation, make described batch of material and/or described glass cullet fusion, simultaneously the gas in the space in the described melting plant is discharged with it.

16, according to the manufacture method of claim 14 or 15 described opticglass, it is characterized in that,

With the spatial volume in the described melting plant is benchmark, replaces gas in this melting plant with 2～20 times/minute speed.

17, a kind of manufacturing installation of opticglass, described opticglass contains SiO at least ₂And/or B ₂O ₃, the manufacturing installation of this opticglass is characterised in that,

Comprise: the batch of material fusion is obtained the batch of material melting plant of glass cullet and/or described glass cullet or described batch of material fusion are obtained the formal melting plant of glass melting thing, the non-oxidizing gas bubbling device is arranged in the described raw mix melting plant and/or in the described glass cullet melting plant.

18, a kind of manufacturing installation of opticglass, described opticglass contains SiO at least ₂And/or B ₂O ₃, the manufacturing installation of this opticglass is characterised in that,

Comprise: fusion tank is used for making batch of material or glass cullet fusion and obtains melts; Body of heater, cover described fusion tank around, and have the peristome that drops into described batch of material or described glass cullet; And air-releasing mechanism, its configuration or connection are used for the gas that described melts produced in the described fusion tank is discharged near described peristome.

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