JP2008266122A - Method for producing glass, preform for precision press molding formed from the glass and optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide high quality glass containing phosphorus, by suppressing wetting-up to an outer periphery of a platinum pipe. <P>SOLUTION: This method for producing glass comprises a process of melting a glass raw material and flowing out the molten glass from a flow-out nozzle made of platinum or a platinum alloy, wherein a gas comprising a halogen gas and/or a halide gas containing an element selected from chlorine, bromine and iodine is introduced to the vicinity of the flow-out nozzle. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing glass, particularly fluorophosphate glass, phosphate glass, a method for producing boric acid-containing glass, glass produced by the method, precision press-molding preform and optical element, and their It relates to a manufacturing method.

  Phosphorus-containing glasses such as fluorophosphate glass and phosphate glass are used in a wide range of applications such as optical glass such as high refractive index and high dispersion glass and low dispersion glass, and filter glass for color sensitivity correction (for example, patents). Reference 1).

  To produce high quality glass such as optical glass, clarification and homogenization are performed in a platinum or platinum alloy container so that impurities do not dissolve in the molten glass in an ultra high temperature state. A method of forming by flowing out from a nozzle made of metal is suitable.

However, in this method, when glass is produced, the glass that has flowed out wets from the lower end of the nozzle to the outer peripheral surface, and the wetted glass is exposed to the outside air for a long time at a high temperature. There was a problem that the quality of the glass deteriorated by taking in the altered glass. Similar problems exist with boric acid-containing glasses.
Japanese National Patent Publication No. 3-500162

  The present invention solves the above-mentioned wet-up problem of such phosphorus-containing glass and boric acid-containing glass, and is used for precision press-molding comprising high-quality optical glass, particularly phosphorus-containing glass, boric acid-containing glass, and the glass. It is an object of the present invention to provide a preform and an optical element, and manufacturing methods thereof.

  As a result of intensive studies to achieve the above object, the present inventor has found that a halogen gas having an element selected from chlorine, bromine and iodine around the molten glass outflow nozzle made of platinum or a platinum alloy and / or It is found that by introducing a halide gas, high-quality glass, for example, phosphorus-containing glass or boric acid-containing glass can be obtained and the object can be achieved, and the present invention is completed based on this finding. It came.

That is, the present invention

(1) In a method for producing glass, comprising melting a glass raw material and flowing out the molten glass from an outflow nozzle made of any material of platinum, platinum alloy, gold, and gold alloy; A method for producing glass, characterized in that molten glass flows out from an outflow nozzle placed in an atmosphere containing a halogen gas and / or halide gas having an element selected from bromine and iodine,
(2) The method for producing glass according to (1) above, wherein the glass is a fluorophosphate glass having a fluorine content of 25% or more in terms of anionic%.
(3) The method for producing a glass as described in (1) above, wherein the glass is phosphate glass having a fluorine content of anionic% of less than 25%.
(4) The method for producing a glass according to (1) above, wherein the outflow nozzle is made of platinum or a platinum alloy, and the glass is boric acid-containing glass.
(5) A method for producing a precision press-molding preform, which produces a precision press-molding preform by processing the glass produced by the method according to any one of (1) to (4) above,
(6) From the outflow nozzle made of any material of platinum, platinum alloy, gold or gold alloy, the molten glass is flowed out to obtain the molten glass lump, and the precision press molding process is performed in the process of cooling the molten glass lump. In a method for producing a precision press-molding preform to be molded into a reformed glass, molten glass is discharged from an outflow nozzle placed in an atmosphere containing a halogen gas and / or a halide gas having an element selected from chlorine, bromine and iodine. A method for producing a precision press-molding preform, characterized by
(7) The method for producing a precision press-molding preform as described in (6) above, wherein the glass is a fluorophosphate glass having a fluorine content of 25% or more in terms of anionic%.
(8) The method for producing a precision press-molding preform as described in (6) above, wherein the glass is a phosphate glass having a fluorine content of anionic% of less than 25%,
(9) The method for producing a precision press-molding preform as described in (6) above, wherein the glass is boric acid-containing glass,
(10) A method for producing an optical element, wherein an optical element is produced by processing the glass produced by the method according to any one of (1) to (4) above,
(11) A method for producing an optical element, characterized in that a precision press-molding preform produced by the method according to any one of (5) to (9) above is heated and precision press-molded,
Is to provide.

  According to the present invention, a method for producing high-quality glass, for example, fluorophosphate glass, phosphate glass, boric acid-containing glass, and a precision press-molding preform and an optical element are produced from the glass produced by the method. A method can be provided.

In the present specification, among phosphorous-containing glass (cationic%, P ⁵⁺ is usually contained 10% or more), a glass having a fluorine content of anionic% of 25% or more is referred to as fluorophosphate glass. Glass having an anionic% content of less than 25% is referred to as phosphate glass.

  In the following description, the platinum outflow nozzle and the platinum alloy outflow nozzle may be collectively referred to as a platinum outflow nozzle. The gold outflow nozzle and the gold alloy outflow nozzle may be collectively referred to as a gold outflow nozzle.

  Moreover, about a platinum alloy and a gold alloy, what is normally used in the glass manufacture field may be used.

  Phosphorus-containing glass such as fluorophosphate glass and phosphate glass has the property of easily getting wet on the outer peripheral surface of the platinum outflow nozzle, but the present inventor has an element selected from an appropriate amount of chlorine, bromine and iodine. By introducing the halogen gas and / or halide gas into the outer peripheral surface of the platinum outflow nozzle or the outer surface of the gold outflow nozzle, the amount of wetting is suppressed and high-quality fluorophosphate glass and phosphate glass are obtained. I found out. The boric acid-containing glass is also a glass whose quality is likely to deteriorate due to the above-mentioned wetting up, but the boric acid-containing glass is also suppressed in the amount of wetting-up by introducing the gas, and a high-quality boric acid-containing glass can be obtained. I found it.

  As the halogen species, the effect is large in the order of chlorine <bromine <iodine. Fluorine gas or fluoride gas is rather unsuitable because it promotes wetting. In addition, even if a halogen element is introduced into the glass itself, the same effect can be obtained. However, the quality may become unstable due to a composition variation caused by the volatilization of the halogen element. Also, when a colorant such as copper ion is introduced into the glass, the color changes and it is difficult to use. On the other hand, introduction of a halogen gas or a halide gas only in the glass outflow atmosphere can prevent wetting without changing the properties of the glass.

  As a method of introducing a gas of halogen gas or halide, a method of introducing chlorine gas using a chlorine gas cylinder, a method of introducing bromine vapor from liquefied bromine, a method of introducing iodine vapor from iodine crystals, diiodomethane, etc. For example, a method of introducing a volatile compound can be used.

  Among these methods, iodine is solid at room temperature and normal pressure, has sublimation properties, is easy to use because it is easy to generate steam, has relatively low toxicity, and has the greatest effect of suppressing wetting. Therefore, it is particularly suitable.

  In the present invention in general, the gas concentration of the halogen gas and / or halide in the atmosphere around the platinum outflow nozzle or the gold outflow nozzle, or the gas in the gas introduced around the platinum outflow nozzle or the gold outflow nozzle The gas concentration of the halogen gas and / or halide depends on the type of halogen element, but from the viewpoint of the effect of suppressing wetting, the halogen element is usually 10 ppm by volume or more, preferably 10 to 1000 ppm by volume, more preferably Is 10 to 500 ppm by volume, more preferably 10 to 200 ppm by volume.

  The glass production method of the present invention includes a step of melting glass raw material and flowing out the molten glass from an outflow nozzle made of any material of platinum, platinum alloy, gold, and gold alloy. In the production method, the molten glass is caused to flow out from an outflow nozzle placed in an atmosphere containing a halogen gas and / or a halide gas having an element selected from chlorine, bromine and iodine. That is, the present invention is a method for producing a glass, comprising a step of melting a glass raw material and flowing out the molten glass from an outflow nozzle made of any material of platinum, platinum alloy, gold, and gold alloy. As described above, a halogen gas and / or a halide gas having an element selected from chlorine, bromine and iodine is introduced around the outflow nozzle.

The present invention is classified into the following three typical embodiments depending on the glass to be produced.
The first aspect is a manufacturing method characterized in that the glass is a fluorophosphate glass having a fluorine content of 25% or more in terms of anionic%, and the second aspect is that the glass has a fluorine content. It is a manufacturing method characterized in that it is a phosphate glass having anionic% of less than 25%. In the third aspect, the outflow nozzle is made of platinum or a platinum alloy, and the glass is made of boron. It is a manufacturing method characterized by being acid-containing glass.

  That is, the first aspect is a method for producing a glass including a step of melting a glass raw material, and outflowing and forming molten glass from an outflow nozzle made of any material of platinum, platinum alloy, gold, and gold alloy. In the method, the glass is a fluorophosphate glass having a fluorine content of 25% or more in terms of anionic%, and an element selected from chlorine, bromine and iodine is disposed around the outflow nozzle as described above. A glass manufacturing method characterized by introducing a halogen gas and / or a halide gas.

  Among the materials of the above outflow nozzles, platinum and platinum alloys are superior in heat resistance to gold and gold alloys. Therefore, considering the durability of the nozzles, it is possible to use outflow nozzles made of platinum or platinum alloys. preferable.

The present invention also provides a fluorophosphate glass (hereinafter sometimes referred to as a first glass) produced by the above method.
[Fluorophosphate glass]
This fluorophosphate glass contains F ⁻ at 25% or more in anionic% and usually contains P ⁵⁺ at 10% or more in cationic%, and is suitable as a glass for realizing a low dispersion glass. This glass contains fluorine, which exhibits extremely high volatility in the melt state, as a main component. Therefore, the volatilization from the glass wetted on the outer peripheral surface of the platinum nozzle is remarkable, and the quality of the glass is greatly deteriorated due to the wettability. Therefore, the effect obtained by applying the present invention to a fluorophosphate glass is very large.

Examples of the fluorophosphate glass include P ⁵⁺ 10 to 45%, Al ³⁺ 5 to 35%, Mg ²⁺ 0 to 20%, Ca ²⁺ 0 to 25%, Sr ²⁺ 0 to 30%, and Ba in terms of cationic%. ^{2+ 0 to} 33%, Li ⁺ 1 to 30%, Na ⁺ 0 to 10%, K ⁺ 0 to 10%, Y ³⁺ 0 to 5%, B ³⁺ 0 to 15%, F ⁻ and O ^A glass having a molar ratio F ⁻ / (F ⁻ + O ²⁻ ) of the content of F ⁻ with respect to the total amount of ² is 0.25 to 0.85.

  The preferred optical constants in the fluorophosphate glass are a refractive index (nd) of 1.40 to 1.58 and an Abbe number (νd) of 67 to 90.

  The cationic% display is based on the molar ratio of the ratio of each cation component, and the anionic% display is based on the molar ratio of the ratio of each anionic component.

  In the following description, unless otherwise noted, the cation percentage indicates the cationic percentage, and the anion percentage indicates the anionic percentage.

P ⁵⁺ is an important cation component as a glass network former. If it is less than 10%, the stability of the glass is lowered, and if it exceeds 45%, P ⁵⁺ needs to be introduced as an oxide raw material, so the oxygen ratio increases. Does not meet the target optical characteristics. Therefore, the amount is usually 10 to 45%. A preferable range is 10 to 40%.

Al ³⁺ is a component that improves the stability of fluorophosphate glass. If it is less than 5%, the stability is lowered, and if it exceeds 35%, the glass transition temperature (Tg) and the liquidus temperature (LT) are greatly increased. Further, since the molding temperature rises and striae due to surface volatilization at the time of molding occurs, a homogeneous glass molded body, particularly a press molding preform cannot be formed. Therefore, the amount is usually 5 to 35%. A preferable range is 5 to 30%.

A divalent cation component ^{(R 2+) Mg 2+, Ca} 2+, Sr 2+, the introduction of ^{Ba 2+} is contributes to the improvement of stability, two or more than introducing singly, more preferably ^{Ca 2+} , Sr ²⁺ and Ba ²⁺ are introduced. In order to further enhance the effect of introducing the divalent cation component (R ²⁺ ), the total content of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ is preferably 1% or more. Moreover, when it introduces exceeding each upper limit, stability will fall rapidly. Ca ²⁺ and Sr ²⁺ can be introduced in a relatively large amount, but Mg ²⁺ and Ba ²⁺ particularly lower the stability. However, since Ba ²⁺ is a component capable of realizing a high refractive index while maintaining low dispersion, it is preferably introduced in a large amount within a range not impairing stability. Therefore, the amount of Mg ²⁺ is usually 0 to 20%, preferably 0 to 15%, more preferably 1 to 15%. The amount of Ca ²⁺ is usually 0 to 25%, preferably 0 to 20%, more preferably 1 to 20%, and the amount of Sr ²⁺ is usually 0 to 30%, preferably 0 to 25%. Preferably it is 1 to 25%, and the amount of Ba ²⁺ is usually 0 to 33%, preferably 0 to 30%, more preferably 1 to 30%, and further preferably 4 to 30%.

Li ⁺ works to lower the glass transition temperature (Tg) and the melting temperature without impairing the stability, but if it exceeds 30%, the durability of the glass is impaired and at the same time the workability is lowered. Therefore, the amount is usually 1 to 30%. A preferable range is 1 to 25%, and a more preferable range is 5 to 25%.

Na ⁺ and K ⁺ have the effect of lowering the glass transition temperature (Tg), respectively, like Li ⁺ , but at the same time, the thermal expansion coefficient tends to be larger than that of Li ⁺ . Moreover, since NaF and KF have a very high solubility in water as compared with LiF, the water resistance is also deteriorated. Therefore, the amounts of Na ⁺ and K ⁺ are usually 0 to 10%, respectively. Preferred ranges for both Na ⁺ and K ⁺ are 0 to 5% and 0 to 5%, respectively, and more preferably 0 to 3% and 0 to 3%, respectively.

Y ³⁺ has the effect of improving the stability and durability of the glass, but if it exceeds 5%, the stability deteriorates conversely and the glass transition temperature (Tg) rises greatly, so the amount is usually 0-5. %. A preferable range is 0 to 3%.

B ³⁺ tends to volatilize during melting as BF ₃ and causes striae, so the amount is usually 0 to 15%, preferably 0 to 10%, more preferably 0 to 5%. .

From the viewpoint of stably producing high-quality optical glass, the total amount of P ⁵⁺ , Al ³⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , Li ⁺ and Y ³⁺ is over 80% in terms of cationic%. It is preferable to make it more than 90%.

  The glass can contain lanthanoids such as Ti, Zr, Zn, La, and Gd as the cation component in addition to the above cation component as long as the object of the present invention is not impaired.

Ratio of anionic components, while realizing the desired optical properties, in order to obtain an optical glass having excellent stability, F ^- and O ^2-F to the total amount of ^- the molar ratio of the content of F ^- / ( F ⁻ + O ²⁻ ) is usually 0.25 to 0.80, preferably 0.3 to 0.8.

  The first glass exhibits a high transmittance in the visible light region except when a colorant is added. The first glass has a transmittance at a wavelength of 400 nm to 2000 nm (excluding reflection loss on the sample surface) when light is incident on a 10 mm thick sample with both surfaces flat and parallel to each other from a direction perpendicular to the both surfaces. However, it exhibits a light transmittance characteristic of usually 90% or more, preferably 95% or more.

The first glass has a relatively low glass transition temperature among phosphorus-containing glasses. Therefore, it can be used as glass for precision press molding, but when the precision press molding temperature fluctuates to the high temperature side, the glass foams or the surface becomes cloudy, and when it fluctuates to the low temperature side, the glass breaks. Sex is reduced. Thus, by further lowering the glass transition temperature, the appropriate range of the precision press molding temperature can be widened, and the productivity of precision press molding can be improved. From such a viewpoint, the first glass preferably has a glass transition temperature (Tg) of 470 ° C. or lower, and more preferably 430 ° C. or lower. In order to realize such a glass having a low transition temperature, it is preferable to introduce Li ⁺ as a cation component, and the amount is more preferably 5 to 30%.

In the first glass, the glass positively containing Li ⁺ among the alkali metal ions has a relatively small coefficient of thermal expansion and relatively excellent water resistance. Therefore, the glass surface can be finished with a smooth and high quality by polishing the glass and processing it into a preform for press molding or processing into an optical element.

In addition, according to the first glass containing 5% or more of Li ⁺ , it has an optical constant equivalent to that when Li ⁺ is not included, and the melting temperature can be reduced by about 50 ° C. Problems such as coloring of glass, mixing of bubbles and striae due to platinum melting from the container can be further reduced and eliminated.

  Next, the second aspect of the present invention includes a step of melting a glass raw material and flowing out the molten glass from an outflow nozzle made of any material of platinum, platinum alloy, gold, and gold alloy. In producing a phosphate glass having a fluorine content of anionic% of less than 25%, a halogen gas having an element selected from chlorine, bromine and iodine as described above around the outflow nozzle and It is characterized in that a halide gas is introduced.

  The present invention also provides a phosphate glass (hereinafter sometimes referred to as a second glass) produced by the above method.

In addition, since the melting temperature of phosphate glass is higher than the melting temperature of fluorophosphate glass, platinum or a platinum alloy excellent in heat resistance is preferable as the material of the outflow nozzle.
[Phosphate glass]
As the phosphate glass, there are the following 2-a glass and 2-b glass.

  The 2-a phosphate glass is particularly suitable as a low-dispersion glass, and is particularly preferred as a glass that realizes an Abbe number (νd) in the range of 60 to 70.

The phosphate glass, F ^- content is less than 25% anionic% of the normal ^{P 5+,} is intended to include by cationic% 20% or more, for example, by cationic% _{display, PO} 2.5 20 -50%, MgO 0-20%, CaO 0-20%, SrO 0-15%, BaO 0-25%, ZnO 0-15%, LiO _0.5 0-25%, NaO _0.5 0-10 _{%, KO 0.5 0~15%, BO} 1.5 0~40%, AlO 1.5 0~10%, GdO 1.5 0~10%, the glass containing _SbO 1.5 0 to 1% Can be mentioned.

  The glass of the said composition is suitable as glass which implement | achieves glass with a refractive index (nd) of 1.55-1.65.

In the above composition, PO _2.5 is a formed product of glass network structure, and is an essential component for imparting stability that can be produced to glass. However, if the content of PO _2.5 exceeds 50%, the glass transition temperature and yield point temperature increase and the refractive index and weather resistance deteriorate, whereas if it is less than 20%, the glass tends to devitrify. Becomes stronger and the glass becomes unstable, so the content of PO _2.5 is usually in the range of 20 to 50%. Preferably it is 25 to 45% of range.

  MgO serves to increase the weather resistance of the glass, and has the effect of lowering the glass transition temperature, yield point temperature, and liquidus temperature by introducing a small amount of MgO. However, when introduced in a large amount, the devitrification stability of the glass is remarkably deteriorated, and the liquidus temperature may be increased. Therefore, the MgO introduction amount is usually 0 to 20%. Preferably it is 5 to 25% of range.

  CaO improves the stability of the glass and lowers the liquidus temperature. However, the introduction of an excessive amount reduces the durability of the glass and the refractive index. %, Preferably 0 to 15%.

  SrO also works to improve the stability of the glass and lower the liquidus temperature. However, since the durability of the glass is lowered and the refractive index is lowered due to the introduction of an excessive amount, the amount introduced is usually 0-15. %, Preferably 0 to 10%.

  BaO is a component that increases the refractive index of glass, improves devitrification stability, and lowers the liquidus temperature. However, when introduced excessively, not only the glass becomes unstable, but also the liquidus temperature, transition temperature, and yield point temperature increase, so the amount introduced is usually in the range of 0-25%. Preferably it is 0 to 20% of range.

  ZnO functions to greatly reduce the glass transition temperature and increase the stability. However, if introduced excessively, the Abbe number is rapidly reduced, making it difficult to obtain a low dispersion glass. Therefore, the introduction amount is usually in the range of 0 to 15%. Preferably it is 0 to 10% of range.

LiO _0.5 is a component used for lowering the glass forming temperature and the yield point temperature, and lowering the press molding temperature when the optical element is press molded (including precision press molding). When a small amount of LiO _0.5 is introduced, the glass transition temperature is significantly reduced. However, when a large amount is introduced, the weather resistance and stability of the glass are deteriorated, and the refractive index may be drastically lowered. Therefore, the introduction amount is usually set to 0 to 25%. Preferably it is 5 to 20% of range.

Alkali metal oxides such as NaO _0.5 and KO _0.5 both improve the devitrification resistance of the glass, lower the yield point temperature and liquidus temperature, and improve the high-temperature meltability of the glass. It is a component introduced into The introduction of appropriate amounts of NaO _0.5 and KO _0.5 improves the stability of the glass and leads to a decrease in liquidus temperature and transition temperature, but NaO _0.5 exceeds 10% and KO _0.5 increases to 15 If it is introduced in excess of%, not only the stability of the glass is deteriorated but also the weather resistance is remarkably deteriorated. Therefore, the amount of NaO _0.5 introduced is usually 0 to 10%, preferably 0 to 5%. The amount of KO _0.5 introduced is usually 0 to 15%, preferably 0 to 10%.

BO _1.5 is a very effective component for improving the meltability of glass and homogenizing the glass, and at the same time, by introducing a small amount of BO _1.5 , the bonding property of OH inside the glass is changed, and during pressing, It is a very effective component that does not foam glass. However, if BO _1.5 is introduced excessively, the weather resistance of the glass is deteriorated and the stability is also deteriorated. Therefore, the introduction amount is usually in the range of 0 to 40%. Preferably it is 5 to 35% of range.

AlO _1.5 is used as an effective component for improving the weather resistance of glass. However, when introduced excessively, the glass transition temperature is increased, the stability is deteriorated, the high-temperature meltability is also deteriorated, and the refractive index may be lowered. Therefore, the introduction amount is usually 0 to 10%. Preferably it is 0 to 5%.

GdO _1.5 works to greatly improve the weather resistance and refractive index of glass, but if introduced excessively, the Abbe number may decrease and the stability of the glass may deteriorate. Therefore, the introduction amount is usually 0 to 10%. Preferably it is 0 to 5%.

SbO _1.5 is effective as a glass refining agent. However, if added over 1%, the glass is colored or the glass tends to foam during precision press molding, so the amount of introduction is usually 0 to 1%.

In addition, components such as SiO ₂ , YO _1.5 , ZrO ₂ , TaO _2.5 , BiO _1.5 , TeO ₂ , NbO _2.5 , WO ₃ , TiO ₂ , LaO _1.5 are also included in the second glass. As long as the characteristics are not impaired, introduction of 0 to 2% is possible. However, considering the influence on the environment, it is preferable not to use TeO ₂ , PbO, or AsO _1.5 .

  When using the said glass for precision press molding, it is preferable that a transition temperature (Tg) is 550 degrees C or less, and it is more preferable that it is 530 degrees C or less.

  Next, the second-b phosphate glass has an F- content of less than 25% in anionic% and usually contains P5 + in 15% or more in cationic%, and is particularly suitable as a high refractive index and high dispersion glass. It is a thing.

The glass of 2-b is a phosphate glass suitable for realizing high dispersion characteristics, and is suitable for obtaining an Abbe number (νd) of 35 or less, preferably 20-30. The A third glass, by cationic% _{display, PO 2.5 15~40%, NbO 2.5} 3~30%, TiO 2 0~15%, WO 3 0~30%, BiO 1.5 0 _{~15%, BO 1.5 0~25%,} BaO 0~20%, 0~10% ZnO, 0~10% MgO, CaO 0~10%, SrO 0~10%, BaO 0~20%, LiO _0.5 5-30%, NaO _0.5 0-30%, KO _0.5 0-15%, AlO _1.5 0-10%, SiO ₂ 0-10%, LaO _1.5 0-10% it can be exemplified _{GdO 1.5 0~10%, YbO 1.5 0~10} %, ZrO 2 0~10%, the glass containing TaO 2.5 0%.

PO _2.5 is a glass network structure, and is an essential component for providing the glass with a manufacturable stability. However, if the content of PO _2.5 exceeds 40%, the glass transition temperature increases and the weather resistance tends to deteriorate. If it is less than 15 mol%, the glass tends to devitrify and the glass becomes unstable. Therefore, the PO _2.5 content is preferably in the range of 15 to 40%, and in the range of 20 to 35 mol%. Is more preferable.

NbO _2.5 is an indispensable component for imparting characteristics such as high refractive index and high dispersion as described above. However, when the introduced amount exceeds 30%, the glass transition temperature and yield point are increased, the stability is deteriorated, the high temperature melting property is also deteriorated, and there is a tendency that foaming and coloring are easily caused during precision pressing. On the other hand, if the introduction amount is less than 3%, the durability of the glass deteriorates and it becomes difficult to obtain the required high refractive index. Therefore, the introduction amount is preferably in the range of 3 to 30%. A range of 25% is more preferable.

LiO _0.5 is an effective component for lowering the glass transition temperature as described above. Compared with other alkalis, LiO _0.5 is less likely to lower the refractive index and does not deteriorate durability. However, if it exceeds 30%, the stability of the glass is remarkably deteriorated and the durability is also deteriorated. Therefore, the amount of LiO _0.5 introduced is preferably in the range of 5 to 30%. More preferably, it is 5 to 25% of range.

TiO ₂ has the effect of imparting high refractive index and high dispersibility and improving devitrification stability. However, if its content exceeds 15%, the devitrification stability and transmittance of the glass are rapidly deteriorated, the yield point and the liquidus temperature are also rapidly increased, and the glass is easily colored during precision press molding. Therefore, the introduction amount is preferably 0 to 15%, and more preferably 0 to 5%.

WO ₃ is an effective component for imparting a high refractive index / high dispersion characteristic and a low temperature softening property. WO ₃ works to lower the transition temperature and yield point of glass and raise the refractive index, like alkali metal oxides. And since there exists an effect which suppresses the wettability of glass and a press-molding die, there exists an effect that the mold release property of glass becomes very good in the case of precision press molding. However, if excessive introduction of WO ₃ is introduced, for example, exceeding 30%, the glass is likely to be colored, while the high temperature viscosity of the glass is lowered, so that hot forming becomes difficult. Therefore, the content is preferably 0 to 30%, and more preferably 0 to 25%.

BiO _1.5 is a component that imparts a high refractive index and high dispersibility, is a component that has the effect of greatly expanding and stabilizing the glass generation region, and a component that increases the weather resistance of glass. is there. Therefore, by introducing BiO _1.5 , it is possible to vitrify even a glass having a small PO _2.5 content. However, if the introduction amount exceeds 15%, the glass tends to be devitrified and at the same time, the glass tends to be colored, so the content of BiO _1.5 is preferably 0 to 15%. More preferably, it is 10%.

BO _1.5 is an effective component for improving the glass meltability and homogenizing the glass, and at the same time, by introducing a small amount, it changes the bondability of the OH inside the glass, and foams the glass during precision press molding. The effect of suppressing is acquired. However, if BO _1.5 is introduced in an amount of more than 25%, the weather resistance of the glass deteriorates or the glass becomes unstable. Therefore, the amount introduced is preferably in the range of 0 to 25%. A more preferred range is from 0 to 20%.

BaO is a component having an effect of imparting a high refractive index, improving devitrification stability, and lowering the liquidus temperature. When introducing WO3, particularly when introducing a large amount of WO _3, suppressing the coloration of the glass with the introduction of BaO, large effect of enhancing devitrification stability, if less PO _2.5 content, the weather resistance of the glass There is also an effect to increase. However, if the introduced amount of BaO exceeds 20%, not only the glass becomes unstable, but also the transition temperature and the yield point increase, so the introduced amount of BaO is preferably 0 to 20%. More preferably, it is 15%.

  ZnO is a component that can be introduced to increase the refractive index and dispersion of the glass. The introduction of a small amount of ZnO also has the effect of lowering the glass transition temperature, yield point, and liquidus temperature. However, when introduced excessively, the devitrification stability of the glass is remarkably deteriorated, and the liquidus temperature may be increased. Therefore, the ZnO introduction amount is preferably 0 to 10%, more preferably 0 to 5%.

  MgO, CaO, and SrO are components that can be introduced to adjust the stability and weather resistance of the glass. However, if too much is introduced, the glass becomes very unstable. Preferably, 0 to 5% is more preferable.

NaO _0.5 is a component that can be introduced to improve the devitrification resistance of the glass, lower the glass transition temperature and the liquidus temperature, and improve the meltability of the glass. However, when NaO _0.5 is excessive, not only the stability of the glass is deteriorated, but also the weather resistance and durability of the glass may be deteriorated. Therefore, the amount of NaO _0.5 introduced is set to 0 to 30%. And is more preferably 0 to 25%.

KO _0.5 is a component that can be introduced to improve the devitrification resistance of the glass, lower the glass transition temperature and the liquidus temperature, and improve the meltability of the glass. However, if KO _0.5 is excessive, not only the stability of the glass deteriorates, but also the weather resistance and durability of the glass may deteriorate, so the amount of KO _0.5 introduced is 0 to 15%. Is preferable, and it is more preferable to make it 0 to 10%.

AlO _1.5 , SiO ₂ , LaO _1.5 , GdO _1.5 , YbO _1.5 , ZrO ₂ , TaO _2.5 are components that can be introduced when adjusting the stability and optical constant of glass. is there. The content of AlO _1.5 is 0 to 10%, the content of SiO ₂ is 0 to 10%, the content of LaO _1.5 is 0 to 10%, the content of GdO _1.5 is 0 to 10%, The content of YbO _1.5 is preferably 0 to 10%, the content of ZrO ₂ is 0 to 10%, and the content of TaO _2.5 is preferably 0 to 10%.

However, when used for precision press molding, all of the above components increase the glass transition temperature, so in precision press molding glass, the content of AlO _1.5 is 0 to 5% and the content of SiO ₂ is 0-5%, LaO _1.5 content 0-1.5%, GdO _1.5 content 0-5%, YbO _1.5 content 0-5%, ZrO ₂ content The amount is preferably 0 to 5%, and the content of TaO _2.5 is preferably 0 to 5%.

SbO _1.5 is effective as a glass refining agent, but if added over 1%, the glass tends to foam during precision press molding, so the amount introduced should be 0-1%.

Since TeO ₂ is toxic, it is desirable not to use it from the viewpoint of environmental impact. Similarly, it is desirable not to use compounds such as PbO, AsO _1.5 , CdO, TlO _0.5 , radioactive substances, Cr, and Hg. Also, AgO _0.5 is not particularly necessary and is preferably not introduced.

  The preferable range of the optical constant in the second-b glass is that the refractive index (nd) is 1.65 or more, the refractive index (nd) is more preferably 1.75 or more, and 1.8 or more. Further preferred. The upper limit of the refractive index (nd) is not particularly limited, but 2.1 may be used as a guide. On the other hand, the Abbe number (νd) is more preferably 35 or less, and further preferably 30 or less. The lower limit of the Abbe number (νd) is not particularly limited, but 15 may be used as a guide.

  When the second-b glass is used for precision press molding, a glass transition temperature (Tg) of 600 ° C. or lower is preferable.

  When both the 2-a glass and the 2-b glass contain a large amount of volatile alkali metal components, a more remarkable effect can be obtained by applying the present invention. As such glass, there is glass for precision press molding or glass containing about 5 to 40 mol% in total of alkali metal oxides.

  In the melting of the first and second glasses, it is preferable to perform each step of clarification, preferably melting and homogenizing in an inert atmosphere such as nitrogen, and in particular, dry inert gas in a sealed container. It is desirable to carry out while flowing.

Next, the specific manufacturing method of the fluorophosphate glass and phosphate glass of this invention is demonstrated.
[Specific production method of fluorophosphate glass]
Using raw materials such as phosphates, fluorides, carbonates, nitrates and oxides as appropriate, the raw materials are weighed so as to have a desired composition and melted at about 900 to 1200 ° C. in a heat-resistant crucible. Hydroxides and hydrates should not be used because they promote the volatilization of fluorine. Moreover, it is desirable to use a heat-resistant lid at the time of melting. After the molten glass is stirred and clarified, the molten glass is flowed out from an outflow nozzle made of platinum or a platinum alloy to form the glass. The formed glass is transferred to an annealing furnace heated in the vicinity of the glass transition point in advance, and cooled to room temperature to produce a glass molded body. As described above, the molten glass flows out by introducing a halogen gas and / or a halide gas having an element selected from chlorine, bromine and iodine around the platinum outflow nozzle or the gold outflow nozzle. While doing.
[Specific production method of phosphate glass]
Using raw materials such as phosphates, carbonates, nitrates, oxides, and fluorides as appropriate, the raw materials are weighed to obtain a desired composition, and glass raw materials are prepared. Thereafter, in the same manner as in the method for producing the fluorophosphate glass, glass is molded to produce a glass molded body.

  According to a third aspect of the present invention, there is provided a glass including a step of melting a glass raw material and flowing out the molten glass from an outflow nozzle made of any material of platinum, platinum alloy, gold, and gold alloy. In the production method, the molten glass is caused to flow out from an outflow nozzle placed in an atmosphere containing a halogen gas and / or a halide gas having an element selected from chlorine, bromine and iodine. That is, the third aspect is a glass manufacturing method including a step of melting a glass raw material, and outflowing and forming molten glass from an outflow nozzle made of platinum or a platinum alloy, wherein the glass contains boric acid. This is a glass manufacturing method in which a halogen gas and / or a halide gas having an element selected from chlorine, bromine and iodine is introduced around the outflow nozzle as described above.

  The melting temperature of the glass tends to increase in the order of fluorophosphate glass, phosphate glass, and boric acid-containing glass. Therefore, in this embodiment for producing boric acid-containing glass, an outflow nozzle made of platinum or platinum alloy having high heat resistance is used.

The present invention also provides a boric acid-containing glass (hereinafter sometimes referred to as a third glass) produced by the above method.
[Boric acid-containing glass]
A typical boric acid-containing glass in the present invention is a glass containing ₅ to 70 mol% of B ₂ O ₃ . In order to increase the refractive index of the boric acid-containing glass, a glass further containing 5 to 30 mol% of La ₂ O ₃ is also practical. Furthermore, in order to adjust the optical characteristics or lower the glass transition temperature to lower the heating temperature when forming by heating and softening, glass containing 1 to 50 mol% of ZnO is also practical. It can exhibit the following glass Examples of such _{B 2 O 3 -La 2 O 3} -ZnO -containing glass.

In mol% display, as a glass component,
B ₂ O ₃ 5~70%,
SiO ₂ 0-50%,
ZnO 1-50%,
La ₂ O ₃ 5-30%,
Gd ₂ O ₃ 0-22%,
Y ₂ O ₃ 0-10%,
Yb ₂ O ₃ 0-10%,
Li ₂ O 0-20%,
Na ₂ O 0-10%,
K ₂ O 0-10%,
MgO 0-10%,
CaO 0-10%,
SrO 0-10%,
BaO 0-10%,
ZrO ₂ 0-15%,
Ta ₂ O ₅ 0-20%,
WO ₃ 0~20%,
Nb ₂ O ₅ 0-15%,
TiO ₂ 0-40%,
Bi ₂ O ₃ 0-10%,
GeO ₂ 0-10%,
Ga ₂ O ₃ 0~10%,
Al ₂ O ₃ 0-10%,
Including glass.

The glass will be described below. Hereinafter, unless otherwise specified, the amount of each component is expressed in mol%.

B ₂ O ₃ plays the role of an oxide that forms a glass network. When a large amount of high refractive index component such as La ₂ O ₃ is introduced, 5% or more of B ₂ O ₃ is introduced as a main network component for forming glass, and sufficient stability against devitrification is given. At the same time, it is necessary to maintain the meltability of the glass. However, if it is introduced in excess of 70%, the refractive index of the glass is lowered, and it is not suitable for the purpose of obtaining a high refractive index glass. Therefore, the amount of B ₂ O ₃ introduced is 5 to 70%, preferably 10 to 65%, more preferably 10 to 60%, and still more preferably 15 to 60%.

SiO ₂ is a glass containing a large amount of a rare earth oxide component such as La ₂ O ₃ , lowering the liquidus temperature of the glass, improving the high temperature viscosity, and further greatly improving the stability of the glass, Excessive introduction lowers the refractive index of the glass and increases the glass transition temperature, making precision press molding difficult. Therefore, the amount of SiO ₂ introduced is 0 to 50%, preferably 0 to 40%, more preferably 0 to 30%, and still more preferably 0 to 25%.

  ZnO lowers the melting temperature, liquidus temperature and transition temperature of glass, and is indispensable for adjusting the refractive index. When the content is less than 1%, the above effect is weak. When the content exceeds 50%, the dispersion increases, the stability against devitrification deteriorates, and the chemical durability also decreases. The preferred range is 3 to 45%, the more preferred range is 5 to 40%, and the still more preferred range is 10 to 35%.

La ₂ O ₃ increases the refractive index and improves the chemical durability without reducing the stability to devitrification of the glass or without increasing the dispersion. However, if it is less than 5%, a sufficient effect cannot be obtained, and if it exceeds 30%, the stability against devitrification is remarkably deteriorated. Therefore, the introduction amount is 5 to 30%, preferably 5 to 25%, more preferably 5 -22%, more preferably 5-20%.

Gd ₂ O ₃ , like La ₂ O ₃ , is a component that improves the refractive index and chemical durability of glass without deteriorating the stability to glass devitrification and low dispersibility. When Gd ₂ O ₃ is introduced in excess of 22%, the stability against devitrification deteriorates, and the glass transition temperature tends to increase and precision press formability tends to deteriorate. Preferably it is 0 to 20%, more preferably 0 to 18%, still more preferably 0 to 15%.

Y ₂ O ₃ and Yb ₂ O ₃ are optional components that realize a glass having a high refractive index and low dispersion. When introduced in a small amount, the stability of the glass is improved and the chemical durability is improved. By introducing it, the stability of the glass against devitrification is greatly impaired, and the glass transition temperature and yield point temperature are increased. Therefore, the Y ₂ O ₃ content is 0 to 10%, and the Yb ₂ O ₃ content is 0 to 10%.

Li ₂ O has a great effect of lowering the glass transition temperature. However, when it is excessively introduced, the refractive index is lowered and the glass stability is also lowered. Therefore, the amount of Li ₂ O is 0 to 20%, preferably 0 to 15%, more preferably 0 to 10%, and still more preferably 0 to 8%. Incidentally, the amount of Li ₂ O is the case of prioritizing the low-temperature softening property of imparting to 0.1% or more.

Na ₂ O and K ₂ O have a function of improving the meltability. However, since the refractive index and the glass stability are reduced by excessive introduction, the respective introduction amounts are set to 0 to 10%.

  MgO, CaO, and SrO also have a function of improving the meltability. However, since the refractive index and the glass stability are reduced by excessive introduction, the respective introduction amounts are set to 0 to 10%.

  BaO works to increase the refractive index, but the glass stability decreases due to excessive introduction, so the introduction amount is made 0 to 10%.

ZrO ₂ is an essential component used to realize a glass having a high refractive index and maintain the low dispersibility of the glass. By introducing ZrO ₂ , the effect of improving the stability against high temperature viscosity and devitrification can be obtained without lowering the refractive index of the glass, but when introduced over 15%, the liquidus temperature rises rapidly. Since the stability against devitrification is also deteriorated, the introduction amount is 0 to 15%, preferably 0 to 12%, more preferably 0 to 10%, and further preferably 0 to 8%.

Ta ₂ O ₅ is an optional component that realizes a glass having a high refractive index and low dispersion. By introducing Ta ₂ O ₅ , there is an effect of improving the stability against high temperature viscosity and devitrification without lowering the refractive index of the glass, but when introduced over 20%, the liquidus temperature rapidly increases. Since the dispersion increases, the introduction amount is 0 to 20%, preferably 0 to 17%, more preferably 0 to 14%, and still more preferably 0 to 10%.

WO ₃ is a component that is introduced as appropriate in order to improve the stability and meltability of the glass and improve the refractive index. However, if the amount introduced exceeds 20%, the dispersion becomes large and the necessary dispersion characteristics are required. Is not obtained, and the coloration of the glass also increases. Therefore, the introduction amount is 0 to 20%, preferably 0 to 18%, more preferably 0 to 16%, and still more preferably 0 to 14%.

Nb ₂ O ₅ is an optional component that increases the refractive index while maintaining the stability of the glass. However, since dispersion increases due to excessive introduction, the introduction amount is 0 to 15%, preferably 0 to 13%. Preferably it is 0 to 10%, more preferably 0 to 8%.

TiO ₂ is an optional component that can be introduced to improve the refractive index of the glass, but excessive introduction increases the dispersion, making it impossible to obtain the desired optical constant or increasing the coloration of the glass. Therefore, the introduction amount is 0 to 40%. Preferably it is 0 to 35%, more preferably 0 to 30%, and still more preferably 0 to 25%.

Bi ₂ O ₃ is an optional component that functions to increase the refractive index of the glass and improve the stability of the glass. However, excessive introduction reduces the stability of the glass and raises the liquidus temperature. Therefore, the introduction amount is set to 0 to 10%.

GeO ₂ is an optional component that functions to increase the refractive index of the glass and improve the stability of the glass, and its introduction amount is 0 to 10%, preferably 0 to 8%. However, it is more preferable not to introduce since it is extremely expensive compared with other components.

Ga ₂ O _{3 is} also an optional component that functions to increase the refractive index of the glass and improve the stability of the glass, and its introduction amount is 0 to 10%, preferably 0 to 8%. However, it is more preferable not to introduce since it is extremely expensive compared with other components.

Al ₂ O ₃ is an optional component that increases the high temperature viscosity of the glass and lowers the liquidus temperature, improves the moldability of the glass, and also improves the chemical durability. However, the refractive index decreases due to excessive introduction, and the stability against devitrification also decreases, so the introduction amount is set to 0 to 10%.

In addition, Sb ₂ O ₃ is optionally added as a defoaming agent. However, if the amount of Sb ₂ O ₃ added exceeds 1% by weight with respect to the total content of all glass components, press molding is performed during precision press molding. Since the molding surface of the mold may be damaged, Sb ₂ O ₃ is preferably added in an amount of 0 to 1% by weight, preferably 0 to 0.5% by weight, based on the total content of all glass components. It is more preferable to add 0 to 0.1% by weight.

  On the other hand, PbO is mentioned as a preferable material that is not introduced as a glass component. PbO is harmful, and when a preform made of glass containing PbO is precision press-molded in a non-oxidizing atmosphere, lead is deposited on the surface of the molded body and transparency as an optical element is impaired or deposited. There arises a problem that metallic lead adheres to the press mold.

Lu ₂ O ₃ can be introduced as little as 0 to 3%. However, in general, the component of the optical glass is less frequently used than the other components, and is rare and expensive as an optical glass raw material.

  It is desirable not to introduce environmental elements such as cadmium and tellurium, radioactive elements such as thorium, and toxic elements such as arsenic. Moreover, it is desirable not to introduce fluorine because of problems such as volatilization during glass melting.

The glass having the composition in the above range has an optical property with an Abbe number νd of 35 or more and a refractive index nd of 1.70 or more, or an Abbe number νd of less than 35, and the refractive index nd has the following value (1) It is suitable as glass for realizing optical characteristics satisfying the formula.
nd ≧ 2.4−0.02 × νd (1)
In order to obtain desired optical characteristics in such a range, the introduction amount of each component may be determined within the composition range according to the above description.

Next, the specific manufacturing method of the boric acid containing glass of this invention is demonstrated.
[Specific manufacturing method of boric acid-containing glass]
Using raw materials such as carbonates, nitrates and oxides as appropriate, the raw materials are weighed so as to have a desired composition, introduced into a heat-resistant crucible, and heated and melted. After the molten glass is stirred and clarified, the molten glass is flowed out from an outflow nozzle made of platinum or a platinum alloy to form the glass. The formed glass is transferred to an annealing furnace heated in the vicinity of the glass transition point in advance, and cooled to room temperature to produce a glass molded body. As described above, the molten glass flows out while introducing a halogen gas and / or a halide gas having an element selected from chlorine, bromine and iodine around the platinum outflow nozzle.

The glass molded body obtained by the production method of the present invention is appropriately cut, ground and polished. If necessary, the glass molded body can be cut and heat-pressed, or a precision press preform can be produced and heated to be precision press-molded into an aspherical shape or the like. In this way, a desired optical element can be manufactured.
[Precision press molding preform manufacturing method]
There are two embodiments of the method for producing a precision press-molding preform of the present invention.

  A 1st aspect is a manufacturing method of the precision press molding preform which processes the glass produced with the manufacturing method of the glass of the said invention, and produces the preform for precision press molding. For example, the annealed glass is divided into glass pieces called cut pieces, and the obtained glass pieces are ground and polished to produce a preform with a desired shape having a smooth surface.

  The second aspect is a precision press in the process in which the molten glass mass flows out from the outflow nozzle made of any material of platinum, platinum alloy, gold, and gold alloy to obtain the molten glass mass, and the molten glass mass cools. An outflow nozzle placed in an atmosphere containing a halogen gas and / or a halide gas having an element selected from chlorine, bromine and iodine in a method for producing a precision press-molding preform to be molded into a molding preform It is characterized in that the molten glass flows out from. That is, in the second aspect, the molten glass is flowed out from the outflow nozzle made of any material of platinum, platinum alloy, gold, and gold alloy to obtain the molten glass lump, and the molten glass lump is cooled. A method for molding into a precision press-molding preform, wherein a halogen gas and / or a halide gas having an element selected from chlorine, bromine and iodine is introduced around the outflow nozzle.

  In the second aspect, the precision is made of any one of fluorophosphate glass having a fluorine content of 25% or more in anionic%, phosphate glass having a fluorine content of less than 25% in anionic%, and boric acid-containing glass. It is suitable for production of a preform for press molding. The details of each glass are as described above. The outflow nozzle used to manufacture the boric acid-containing glass preform is made of platinum or a platinum alloy, and the outflow nozzle used to manufacture the fluorophosphate glass preform and the phosphate glass preform is heat resistant. Considering the properties, it is preferable to use platinum or a platinum alloy.

  A precision press-molding preform (hereinafter, simply referred to as a preform) is a glass molded body having a weight equal to that of a precision press-molded product, and is preformed in a shape suitable for precision press molding. Is the body. Examples of the shape of the preform include a sphere and a rotating body having one axis of symmetry. The rotating body has a smooth outline with no corners or depressions in an arbitrary cross section including the symmetry axis, for example, an outline having an ellipse whose minor axis coincides with the rotational symmetry axis in the cross section. . In addition, the angle of one of the angles formed by a line connecting an arbitrary point on the contour of the preform in the cross section and the center of gravity of the preform on the axis of symmetry and a tangent tangent to the contour at the point on the contour When θ is θ, when the point starts on the rotational symmetry axis and moves on the contour line, θ increases monotonously from 90 °, then decreases monotonically, then monotonously increases, and the contour line becomes the symmetry axis. A shape that is 90 ° at the other point that intersects with is preferable. The preform is heated and used for press molding so as to have a press-moldable viscosity.

  The preform may be provided with a thin film such as a release film on the surface as necessary. Examples of the release film include a carbon-containing film and a self-assembled film. The preform can be press-molded with an optical element having a required optical constant.

  Next, the second embodiment of the preform manufacturing method of the present invention will be specifically described. In this aspect, precision press molding is performed by forming a glass lump obtained by separating molten glass flowing out from a nozzle made of any material of platinum, platinum alloy, gold, and gold alloy while the glass cools. Manufactures preforms. In addition, the outflow of the molten glass has an element selected from chlorine, bromine and iodine around the outflow nozzle made of any material of platinum, platinum alloy, gold, and gold alloy as described above. The process is carried out while introducing a halogen gas and / or a halide gas. By introducing the halogen gas and / or halide gas around the outflow nozzle, it is possible to suppress the molten glass from getting wet to the outer peripheral surface of the outflow nozzle. In addition, what material should be selected among the said materials should just determine with the glass to be used. The relationship between the nozzle material and the glass is as described above.

  This manufacturing method has an advantage that machining such as cutting, grinding, and polishing is unnecessary. In preforms that have been machined, the distortion of the glass must be reduced to such an extent that it is not damaged by annealing prior to machining. However, according to the preform manufacturing method, the annealing treatment for preventing damage is not necessary. A preform having a smooth surface can also be formed. Furthermore, since the entire surface is a surface formed by solidifying glass in a molten state, there are no fine scratches or latent scratches due to polishing. Therefore, in addition to the excellent chemical durability and weather resistance of the glass itself, the surface area of the preform is small compared to that having scratches due to the smooth surface. For this reason, even if it is placed in the atmosphere, it is difficult for the surface to change in quality, so that a clean surface state immediately after molding can be maintained for a long time.

Further, in the preform manufacturing method, the preform is preferably molded in a floating state to which wind pressure is applied, from the viewpoint of providing a smooth and clean surface. In the said manufacturing method, when it cuts and isolate | separates with a cutting blade when isolate | separating a molten glass, the cutting trace called a shear mark will generate | occur | produce. When the shear mark of the preform remains in the precision press-molded product, the portion becomes a defect, and therefore separation that cannot perform the shear mark is desired. As a method of separating molten glass without using a cutting blade and generating a shear mark, a method of dropping molten glass from an outflow pipe, or a molten glass lump of a predetermined weight that supports the tip of the molten glass flow flowing out of the outflow pipe There is a method of removing the above-mentioned support at a timing that can be separated (referred to as descending cutting method). In the descending cutting method, the glass is separated at the constricted portion formed between the front end side and the outflow pipe side of the molten glass flow, and a molten glass lump having a predetermined weight can be obtained. Subsequently, a preform can be obtained by forming the molten glass ingot into a shape suitable for use in press molding while the molten glass ingot is in a softened state.

When forming a preform in the process of cooling a molten glass lump, surface defects such as devitrification and striae that occur during the forming process can be obtained by precision press molding the surface of the preform as a result. It also remains on the surface of the optical element. Among these, fluorophosphate glass, phosphate glass, and boric acid-containing glass are glasses that tend to deteriorate in quality due to wetting on the outer peripheral surface of the nozzle. According to the present invention, the wet-up is suppressed, the occurrence of defects in the preform can be prevented, and a high-quality preform can be produced efficiently.
[Method for Manufacturing Optical Element]
There are two modes in the method for producing an optical element of the present invention. The first aspect is an optical element manufacturing method in which an optical element is manufactured by processing glass prepared by the glass manufacturing method of the present invention, and the second aspect is the precision press-molding process of the present invention. An optical element manufacturing method comprising heating a precision press-molding preform produced by a reforming manufacturing method and performing precision press-molding.

  According to the method for producing an optical element of the present invention, it is possible to efficiently produce a high-quality optical element, for example, an optical element composed of any one of the above-mentioned fluorophosphate glass, phosphate glass, and boric acid-containing glass. it can.

  Specific examples of the first aspect are shown below. In the first example, molten glass is cast into a mold and formed into a block shape, and then annealed, cut or cleaved, and divided into glass pieces called cut pieces. Then, the glass piece is ground or ground and polished to obtain a glass material for press molding. This glass material is heated and softened and press-molded to produce an optical element blank approximating the shape of the optical element. The blank is annealed and then ground and polished to finish the optical element. In the second example, the block-like glass obtained in the first example is annealed, cut, ground, and polished to obtain an optical element. In the third example, the glass piece obtained in the first example is heated and softened and pressed with a plurality of rotating rollers to form a round bar shape. The obtained round bar glass is annealed and then cut perpendicular to the longitudinal direction. The obtained glass piece is ground and polished to obtain an optical element. In the fourth example, the glass piece obtained in the third example is ground or ground and polished to obtain a glass material for press molding, and the glass material is heated and softened, and press molded to obtain an optical element blank. After the obtained optical element blank is annealed, it is ground and polished to finish the optical element. In the fifth example, molten glass is supplied to a press mold, and before the glass is cooled and solidified, press molding is performed to obtain an optical element blank, which is then finished into an optical element by grinding and polishing. In the sixth example, molten glass is cast into a cylindrical mold and formed into a rod shape, annealed, cut or cleaved to obtain a glass piece, and the glass piece is ground and polished to obtain an optical element. In the seventh example, the glass piece obtained in the sixth example is heated and softened, press-molded to obtain an optical element blank, and further ground and polished to obtain an optical element. In the eighth example, the glass material for press molding obtained by grinding and polishing in the first example or the fourth example is used as a preform, and this preform is heated and precision press-molded to obtain an optical element. In the eighth example, the non-optical functional surface of the precision press-molded product may be ground, polished, or ground and polished to finish the optical element. For example, an aspherical lens may be produced by precision press molding and finished by centering.

  Examples of the optical element produced by the method of the present invention include various lenses such as a spherical lens, an aspherical lens, and a microlens, a diffraction grating, a lens with a diffraction grating, a lens array, and a prism.

  The optical element may be provided with an optical thin film such as an antireflection film, a total reflection film, a partial reflection film, or a film having spectral characteristics, if necessary.

  Next, precision press molding in the eighth example of the first aspect and the second aspect will be described.

  The precision press molding method is also called a mold optics molding method, which is already well known in the technical field to which the present invention belongs.

  A surface that transmits, refracts, diffracts, or reflects light rays of the optical element is called an optical functional surface. For example, taking a lens as an example, a lens surface such as an aspherical surface of an aspherical lens or a spherical surface of a spherical lens corresponds to an optical function surface. The precision press molding method is a method of forming an optical functional surface by press molding by precisely transferring a molding surface of a press mold to glass. That is, it is not necessary to add machining such as grinding or polishing to finish the optical functional surface.

  Therefore, this method is suitable for manufacturing optical elements such as lenses, lens arrays, diffraction gratings, and prisms, and is particularly optimal when manufacturing aspherical lenses with high productivity.

  As a press mold used in the precision press molding method, a known mold, for example, a mold surface of a mold material such as silicon carbide, cemented carbide, stainless steel, etc., can be used. A press-molding die made is preferable. As the release film, a carbon-containing film, a noble metal alloy film, or the like can be used, but a carbon-containing film is preferable from the viewpoint of durability and cost.

  In the precision press molding method, it is desirable that the molding atmosphere be a non-oxidizing gas in order to keep the molding surface of the press mold in a good state. The non-oxidizing gas is preferably nitrogen or a mixed gas of nitrogen and hydrogen.

Next, a precision press molding method particularly suitable for a method of manufacturing an optical element using a preform will be described.
[Precision press molding method 1]
This method is characterized in that the preform is introduced into a press mold, the mold and the preform are heated together, and precision press molding is performed (referred to as precision press molding method 1).

In the precision press molding method 1, the temperature of the press mold and the preform is heated to a temperature at which the glass constituting the preform exhibits a viscosity of 10 ⁶ to 10 ¹² dPa · s to perform precision press molding. preferable.

In addition, the glass is cooled to a temperature at which the glass exhibits a viscosity of 10 ¹² dPa · s or more, more preferably 10 ¹⁴ dPa · s or more, more preferably 10 ¹⁶ dPa · s or more, and then the precision press-molded product is removed from the press mold. It is desirable to take it out.

Under the above conditions, the shape of the molding surface of the press mold can be accurately transferred with glass, and the precision press molded product can be taken out without being deformed.
[Precision press molding method 2]
This method is characterized by introducing a preheated preform into a press mold and performing precision press molding (referred to as precision press molding method 2).

  According to this method, since the preform is preliminarily heated before being introduced into the press mold, it is possible to manufacture an optical element with good surface accuracy free from surface defects while shortening the cycle time.

  The preheating temperature of the press mold is preferably set lower than the preheating temperature of the preform. Thus, by lowering the preheating temperature of the press mold, the consumption of the mold can be reduced.

In the precision press molding method 2, it is desirable that the glass constituting the preform is preheated to a temperature exhibiting a viscosity of 10 ⁹ dPa · s or less, more preferably 10 ^5.5 to 10 ⁹ dPa · s. Further, it is preferable to preheat the preform while floating.

  Furthermore, it is preferable to start cooling the glass simultaneously with the start of pressing or in the middle of pressing.

The temperature of the press mold is adjusted to a temperature lower than the preheating temperature of the preform, and the temperature at which the glass exhibits a viscosity of 10 ⁹ to 10 ¹² dPa · s may be used as a guide.

In this method, it is preferable that after the press molding, the glass is cooled to a viscosity of 10 ¹² dPa · s or more and then released.

  The precision press-molded optical element is taken out from the press mold and gradually cooled as necessary. When the molded product is an optical element such as a lens, an optical thin film may be coated on the surface as necessary.

  Phosphorus-containing glass such as fluorophosphate glass and phosphate glass has the property of easily getting wet on the outer peripheral surface of the platinum outflow nozzle and the outer peripheral surface of the gold outflow nozzle. Wetting can be reduced by introducing a halogen gas and / or halide gas having an element selected from chlorine, bromine and iodine around the periphery, and avoiding the contamination and coloring of platinum. Therefore, it is possible to provide high-quality fluorophosphate glass and phosphate glass, and high-quality optical elements made of these glasses.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
Example 1
As raw materials for glass, phosphates and fluorides corresponding to the respective glass components are used, and Table 1-1, Table 1-2, Table 1-3, Table 1-4, Table 2-1, Table 2- 2, Table 2-3, Table 3-1, Table 3-2, Table 3-3, Table 3-4, Table 3-5, and the raw materials are weighed so that the glass has the composition shown in Table 3-6. did. In these tables, each cation component, O anion component and F anion component indicate the abundance ratio in the obtained glass. After sufficiently mixing the raw materials, the mixture was put into a platinum crucible and heated and melted in the atmosphere over 1 to 3 hours with stirring in a temperature range of 850 to 950 ° C. in an electric furnace. The glass melt that has been homogenized and clarified flows out at a constant flow rate from a platinum alloy nozzle that has been temperature adjusted to a temperature range that allows stable outflow without devitrification of the glass, and puts it into a carbon mold. Casted. The cast glass was allowed to cool to the transition temperature and then immediately put into an annealing furnace, annealed near the transition temperature for 1 hour, and gradually cooled to room temperature in the annealing furnace to obtain each optical glass.

  Note that nitrogen containing iodine gas was introduced around the platinum alloy nozzle through the iodine crystal. At this time, it was confirmed that nitrogen gas contained 50 ppm by volume of iodine. As a result, when iodine gas was not introduced, wetting was observed on the entire circumference of the platinum nozzle in any glass composition, and the wetting portion was crystallized. When iodine was introduced, no wetting was observed in any glass composition.

  When each obtained glass was magnified and observed with a microscope, no precipitation of crystals or unmelted raw material was observed.

  About the obtained optical glass, the result of having measured refractive index (nd), Abbe number ((nu) d), and glass transition temperature (Tg) as follows is shown in Table 1-1, Table 1-2, Table 1-. 3, Table 1-4, Table 2-1, Table 2-2, Table 2-3, Table 3-1, Table 3-2, Table 3-3, Table 3-4, Table 3-5, Table 3- It is shown in FIG.

In addition, about a fluorophosphate glass, the same result can be obtained using the outflow nozzle made from a gold alloy.
(1) Refractive index (nd) and Abbe number (νd)
It measured about the optical glass obtained by making slow cooling temperature-fall rate -30 degreeC / hour.
(2) Glass transition temperature (Tg)
The temperature was increased by a thermomechanical analyzer (Thermo Plus TMA 8310) manufactured by Rigaku Denki Co., Ltd. at a heating rate of 4 ° C./min.

表１−１、表１−２、表１−３、表１−４、表２−１、表２−２、表２−３、表３−１、表３−２、表３−３、表３−４、表３−５、表３−６に示すように、いずれの光学ガラスも、所望の屈折率、アッベ数、ガラス転移温度を有し、優れた低温軟化性、熔解性を示し、精密プレス成形用の光学ガラスとして好適なものであった。

Table 1-1, Table 1-2, Table 1-3, Table 1-4, Table 2-1, Table 2-2, Table 2-3, Table 3-1, Table 3-2, Table 3-3, As shown in Table 3-4, Table 3-5, and Table 3-6, each optical glass has a desired refractive index, Abbe number, and glass transition temperature, and exhibits excellent low-temperature softening properties and meltability. It was suitable as an optical glass for precision press molding.

  Next, Table 1-1, Table 1-2, Table 1-3, Table 1-4, Table 2-1, Table 2-2, Table 2-3, Table 3-1, Table 3-2, Table 3- 3, the temperature range in which each clarified and homogenized molten glass having each composition shown in Table 3-4, Table 3-5, and Table 3-6 can be stably discharged without devitrification. The temperature was adjusted from a platinum alloy nozzle to a constant flow rate, and after dropping or supporting the molten glass flow tip using a support, the support was rapidly lowered to separate the glass mass. The molten glass mass with the weight of the preform to be separated was separated. Next, each of the obtained molten glass lumps was received in a receiving mold having a gas outlet at the bottom, and gas was ejected from the gas outlet and molded while the glass lumps were floated to prepare a press molding preform. The shape of the preform was made spherical or flat spherical by adjusting and setting the separation interval of the molten glass. The weights of the obtained preforms precisely matched the set values, and all of the preforms had a smooth surface. Note that iodine gas was introduced around the platinum alloy nozzle in the same manner as described above.

  At that time, wetting of the glass melt from the glass outlet of the platinum alloy pipe to the outer peripheral surface of the pipe was not observed.

  As another method, the entire surface of the molded spherical preform was polished by a known method, and the entire surface layer was removed to obtain an optically homogeneous preform.

  Separately, a glass melt is cast into a mold from a platinum alloy nozzle with iodine gas introduced in the periphery, molded into a plate glass or cylindrical rod shape, annealed, and then obtained by cutting the glass. The surface of the piece was ground and polished to obtain a preform having a smooth entire surface.

  In any of the methods, wetting of the glass melt from the glass outlet of the platinum alloy pipe to the outer peripheral surface of the pipe was not recognized.

The preform obtained as described above was precision press-molded using the press apparatus shown in FIG. 1 to obtain an aspheric lens. Specifically, after the preform 4 is placed between the lower mold 2 and the upper mold 1 of the press mold composed of the upper mold 1, the lower mold 2 and the body mold 3, the inside of the quartz tube 11 is placed in a nitrogen atmosphere as a heater. The quartz tube 11 was heated by energization. The temperature inside the press mold is set to a temperature at which the glass to be molded exhibits a viscosity of 10 ⁸ to 10 ¹⁰ dPa · s, and while maintaining the same temperature, the push bar 13 is lowered and the upper mold 1 is pressed to form. The preform set in the mold was pressed. The press pressure was 8 MPa, and the press time was 30 seconds. After pressing, the pressure of the press is released, and the glass molded product that has been press-molded is gradually brought to a temperature at which the viscosity of the glass reaches 10 ¹² dPa · s or more with the lower mold 2 and the upper mold 1 in contact with each other. It was cooled and then rapidly cooled to room temperature, and the glass molded product was removed from the mold and an aspherical lens was obtained. The obtained aspherical lens had extremely high surface accuracy.

  In FIG. 1, reference numeral 9 is a support rod, reference numeral 10 is a lower mold, a barrel holder, and reference numeral 14 is a thermocouple.

  An aspherical lens obtained by precision press molding was provided with an antireflection film as required.

Next, the same preform as the above preforms was precision press-molded by a method different from the above method. In this method, first, the preform was preheated to a temperature at which the viscosity of the glass constituting the preform was 10 ⁸ dPa · s while the preform floated. On the other hand, a press mold having an upper mold, a lower mold, and a body mold is heated to a temperature at which the glass constituting the preform exhibits a viscosity of 10 ⁹ to 10 ¹² dPa · s, and the preheated preform is pressed. It was introduced into the mold cavity and precision press-molded at 10 MPa. Cooling of the glass and the press mold was started at the start of pressing, and the glass was cooled until the viscosity of the molded glass reached 10 ¹² dPa · s or more, and then the molded product was released to obtain an aspheric lens. The obtained aspherical lens had extremely high surface accuracy.

An aspherical lens obtained by precision press molding was provided with an antireflection film as required.
In this way, a glass optical element with high internal quality could be obtained with high productivity and high accuracy.

  Next, the glass is melted so that each of the above-mentioned fluorophosphate glass and phosphate glass can be obtained, and the molten glass is cast into a mold and formed into a block shape, and then annealed, cut or cleaved to obtain a glass piece. Divided into Then, these glass pieces were ground to form a glass material for press molding, and an optical element blank approximated to the optical element shape was prepared by heating, softening, and press molding. Furthermore, the obtained optical element blank was annealed and then ground and polished to produce a spherical lens.

  Next, the block-shaped glass was annealed, cut, ground, and polished to produce a spherical lens, a prism, and the like.

  Furthermore, the lath piece is heated and softened, pressed with a plurality of rotating rollers, formed into a round bar shape, annealed, cut perpendicular to the longitudinal direction, and the resulting glass piece is ground and polished. A spherical lens was produced.

  Next, the glass piece obtained from the round bar glass was ground to obtain a glass material for press molding. This glass material was heated, softened, press molded, annealed, ground, and polished to obtain a spherical lens. .

  Next, the molten glass was supplied to a press mold, and before the glass cooled and solidified, press molding was performed to obtain an optical element blank, and a spherical lens was produced by grinding and polishing.

  Further, the molten glass was cast into a cylindrical mold, formed into a rod shape, annealed, and then cleaved to obtain a glass piece. The glass piece was ground and polished to obtain a spherical lens and a prism.

  Furthermore, the glass piece obtained from the rod-shaped glass was heated and softened, press-molded to obtain an optical element blank, and further ground and polished to obtain a spherical lens and a prism.

  Next, the preform obtained by annealing, cutting, grinding and polishing the block glass and round bar glass was heated and precision press molded to obtain an aspherical lens.

  In each of the above examples, a spherical lens, an aspherical lens, and a prism are manufactured. In addition, various lenses such as a microlens, a diffraction grating, a lens with a diffraction grating, and various optical elements such as a lens array are also manufactured. be able to.

  These optical elements may be provided with an optical thin film such as an antireflection film, a total reflection film, a partial reflection film, or a film having spectral characteristics, if necessary.

Example 2
As raw materials for glass, boric acid, oxides, carbonates, nitrates and the like corresponding to the respective glass components were used, and the raw materials were weighed so as to become glasses having the compositions shown in Tables 4-1 and 4-2. . After sufficiently mixing the raw materials, the mixture was put into a platinum crucible and melted by heating in the atmosphere over 1 to 3 hours while stirring in an electric furnace. The glass melt that has been homogenized and clarified flows out at a constant flow rate from a platinum alloy nozzle that has been temperature adjusted to a temperature range that allows stable outflow without devitrification of the glass, and puts it into a carbon mold. Casted. The cast glass was allowed to cool to the transition temperature and then immediately put into an annealing furnace, annealed near the transition temperature for 1 hour, and gradually cooled to room temperature in the annealing furnace to obtain each optical glass.

  In addition, nitrogen containing iodine gas was introduced around the platinum alloy nozzle through the iodine crystal. At this time, it was confirmed that the nitrogen gas contained 50 ppm by volume of iodine. As a result, when iodine gas was not introduced, wetting was observed on the entire circumference of the platinum nozzle in any glass composition, and the wetting portion was crystallized. When iodine was introduced, no wet-up was observed in any glass composition.

  When each obtained glass was magnified and observed with a microscope, no precipitation of crystals or unmelted raw material was observed.

About the obtained optical glass, the result of having measured refractive index (nd), Abbe number ((nu) d), and glass transition temperature (Tg) as follows is shown to Table 4-1, Table 4-2.
(1) Refractive index (nd) and Abbe number (νd)
It measured about the optical glass obtained by making slow cooling temperature-fall rate -30 degreeC / hour.
(2) Glass transition temperature (Tg)
The temperature was increased by a thermomechanical analyzer (Thermo Plus TMA 8310) manufactured by Rigaku Denki Co., Ltd. at a heating rate of 4 ° C./min.

表４−１、表４−２に示すように、いずれの光学ガラスも、所望の屈折率、アッベ数、ガラス転移温度を有し、優れた低温軟化性、熔解性を示し、精密プレス成形用の光学ガラスとして好適なものであった。

As shown in Tables 4-1 and 4-2, each optical glass has a desired refractive index, Abbe number, and glass transition temperature, exhibits excellent low-temperature softening properties and meltability, and is used for precision press molding. It was suitable as an optical glass.

  Next, the clarified and homogenized molten glass having each composition shown in Table 4-1 and Table 4-2 was temperature adjusted to a temperature range in which stable outflow was possible without causing the glass to devitrify. The weight of the target preform by a method in which a glass alloy nozzle is made to flow out from a platinum alloy nozzle at a constant flow rate and supports the molten glass flow tip using a support or a support, and then the support is rapidly lowered to separate the glass block. The molten glass ingot was separated. Next, each of the obtained molten glass lumps was received in a receiving mold having a gas outlet at the bottom, and gas was ejected from the gas outlet and molded while the glass lumps were floated to prepare a press molding preform. The shape of the preform was made spherical or flat spherical by adjusting and setting the separation interval of the molten glass. The weights of the obtained preforms precisely matched the set values, and all of the preforms had a smooth surface. In addition, iodine gas was introduced into the periphery of the platinum alloy nozzle in the same manner as described above.

  At that time, wetting of the glass melt from the glass outlet of the platinum alloy pipe to the outer peripheral surface of the pipe was not observed.

  As another method, the entire surface of the molded spherical preform was polished by a known method, and the entire surface layer was removed to obtain an optically homogeneous preform.

  Separately, a glass melt is cast into a mold from a platinum alloy nozzle with iodine gas introduced in the periphery, molded into a plate glass or cylindrical rod shape, annealed, and then obtained by cutting the glass. The surface of the piece was ground and polished to obtain a preform having a smooth entire surface.

  In any of the methods, wetting of the glass melt from the glass outlet of the platinum alloy pipe to the outer peripheral surface of the pipe was not recognized.

The preform obtained as described above was precision press-molded using the press apparatus shown in FIG. 1 to obtain an aspheric lens. Specifically, after the preform 4 is placed between the lower mold 2 and the upper mold 1 of the press mold composed of the upper mold 1, the lower mold 2 and the body mold 3, the inside of the quartz tube 11 is placed in a nitrogen atmosphere as a heater. The quartz tube 11 was heated by energization. The temperature inside the press mold is set to a temperature at which the glass to be molded exhibits a viscosity of 10 ⁸ to 10 ¹⁰ dPa · s, and while maintaining the same temperature, the push bar 13 is lowered and the upper mold 1 is pressed to form. The preform set in the mold was pressed. The press pressure was 8 MPa, and the press time was 30 seconds. After pressing, the pressure of the press is released, and the glass molded product that has been press-molded is gradually brought to a temperature at which the viscosity of the glass reaches 10 ¹² dPa · s or more with the lower mold 2 and the upper mold 1 in contact with each other. It was cooled and then rapidly cooled to room temperature, and the glass molded product was removed from the mold and an aspherical lens was obtained. The obtained aspherical lens had extremely high surface accuracy.

  In FIG. 1, reference numeral 9 is a support rod, reference numeral 10 is a lower mold, a barrel holder, and reference numeral 14 is a thermocouple.

  An aspherical lens obtained by precision press molding was provided with an antireflection film as required.

Next, the same preform as the above preforms was precision press-molded by a method different from the above method. In this method, first, the preform was preheated to a temperature at which the viscosity of the glass constituting the preform was 10 ⁸ dPa · s while the preform floated. On the other hand, a press mold having an upper mold, a lower mold, and a body mold is heated to a temperature at which the glass constituting the preform exhibits a viscosity of 10 ⁹ to 10 ¹² dPa · s, and the preheated preform is pressed. It was introduced into the mold cavity and precision press-molded at 10 MPa. Cooling of the glass and the press mold was started at the start of pressing, and the glass was cooled until the viscosity of the molded glass reached 10 ¹² dPa · s or more, and then the molded product was released to obtain an aspheric lens. The obtained aspherical lens had extremely high surface accuracy.

  An aspherical lens obtained by precision press molding was provided with an antireflection film as required.

  In this way, a glass optical element with high internal quality could be obtained with high productivity and high accuracy.

  Next, the glass was melted so as to obtain each of the boric acid-containing glasses, and the molten glass was cast into a mold and formed into a block shape, and then annealed, cut or cleaved, and divided into glass pieces. Then, these glass pieces were ground to form a glass material for press molding, and an optical element blank approximated to the optical element shape was prepared by heating, softening, and press molding. Furthermore, the obtained optical element blank was annealed and then ground and polished to produce a spherical lens.

  Next, the block-shaped glass was annealed, cut, ground, and polished to produce a spherical lens, a prism, and the like.

  Furthermore, the lath piece is heated and softened, pressed with a plurality of rotating rollers, formed into a round bar shape, annealed, cut perpendicular to the longitudinal direction, and the resulting glass piece is ground and polished. A spherical lens was produced.

  Next, the glass piece obtained from the round bar glass was ground to obtain a glass material for press molding. This glass material was heated, softened, press molded, annealed, ground, and polished to obtain a spherical lens. .

  Next, the molten glass was supplied to a press mold, and before the glass cooled and solidified, press molding was performed to obtain an optical element blank, and a spherical lens was produced by grinding and polishing.

  Further, the molten glass was cast into a cylindrical mold, formed into a rod shape, annealed, and then cleaved to obtain a glass piece. The glass piece was ground and polished to obtain a spherical lens and a prism.

  Furthermore, the glass piece obtained from the rod-shaped glass was heated and softened, press-molded to obtain an optical element blank, and further ground and polished to obtain a spherical lens and a prism.

  Next, the preform obtained by annealing, cutting, grinding and polishing the block glass and round bar glass was heated and precision press molded to obtain an aspherical lens.

  In each of the above examples, a spherical lens, an aspherical lens, and a prism are manufactured. In addition, various lenses such as a microlens, a diffraction grating, a lens with a diffraction grating, and various optical elements such as a lens array are also manufactured. be able to.

  These optical elements may be provided with an optical thin film such as an antireflection film, a total reflection film, a partial reflection film, or a film having spectral characteristics, if necessary.

  According to the glass manufacturing method of the present invention, by introducing a halogen gas and / or a halide gas having an element selected from chlorine, bromine and iodine around the platinum outflow nozzle, the outer periphery of the platinum nozzle As a result, wetting can be reduced and high-quality glass can be obtained.

It is a figure which shows the precision press molding example of the preform for press molding of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper mold | type 2 Lower mold | type 3 Drum type | mold 4 Preform 9 Support rod 10 Lower mold | type, barrel type | mold holder 11 Quartz tube 13 Push rod 14 Thermocouple

Claims (11)

In a glass manufacturing method including a step of melting a glass raw material and outflowing and forming molten glass from an outflow nozzle made of any material of platinum, platinum alloy, gold, and gold alloy,
A method for producing glass, characterized in that molten glass flows out from an outflow nozzle placed in an atmosphere containing halogen gas and / or halide gas having an element selected from chlorine, bromine and iodine.   The method for producing glass according to claim 1, wherein the glass is a fluorophosphate glass having a fluorine content of 25% or more in terms of anionic%.   The method for producing glass according to claim 1, wherein the glass is phosphate glass having a fluorine content of anionic% of less than 25%.   The method for producing glass according to claim 1, wherein the outflow nozzle is made of platinum or a platinum alloy, and the glass is boric acid-containing glass.   The manufacturing method of the precision press molding preform which processes the glass produced by the method in any one of Claims 1-4, and produces the precision press molding preform. From the outflow nozzle made of any material of platinum, platinum alloy, gold, gold alloy, molten glass is flowed out to obtain a molten glass lump, and molded into a precision press molding preform in the process of cooling the molten glass lump. In the manufacturing method of the precision press molding preform,
A precision press molding preform characterized in that molten glass flows out from an outflow nozzle placed in an atmosphere containing a halogen gas and / or a halide gas having an element selected from chlorine, bromine and iodine. Production method.   The method for producing a precision press-molding preform according to claim 6, wherein the glass is a fluorophosphate glass having a fluorine content of 25% or more in terms of anionic%.   The method for producing a precision press-molding preform according to claim 6, wherein the glass is phosphate glass having a fluorine content of anionic% and less than 25%.   The method for producing a precision press-molding preform according to claim 6, wherein the outflow nozzle is made of platinum or a platinum alloy, and the glass is boric acid-containing glass.   The manufacturing method of the optical element which processes the glass produced by the method in any one of Claims 1-4, and produces an optical element.   A method for producing an optical element, wherein the precision press-molding preform produced by the method according to claim 5 is heated and precision press-molded.

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