JP2011153042A - Production method of optical glass and optical instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method of optical glass for obtaining a P<SB>2</SB>O<SB>5</SB>component-containing glass which has high dispersion and yet is little discolored without being subjected to heat treatment, and of which the discoloring after subjected to heat treatment is reduced. <P>SOLUTION: There is provided the production method of optical glass which contains, as essential components, a P<SB>2</SB>O<SB>5</SB>component and one or more selected from the group consisting of an Nb<SB>2</SB>O<SB>5</SB>component, a TiO<SB>2</SB>component and a WO<SB>3</SB>component, and the method comprises a step of melting glass raw material (melting step), a step of refining molten glass raw material (refining step), a step of stirring refined molten glass (stirring step), a step of effusing stirred molten glass (effusing step), and a step of molding effused glass (molding step), wherein the stirring step is performed at a temperature higher than a liquid phase temperature of the molten glass by 0-200°C. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical glass manufacturing method and an optical apparatus.

  In recent years, optical devices that use optical lenses have been rapidly improved in functionality, and accordingly, there is an increasing demand for higher accuracy for optical lenses. The market requirements for high precision include, specifically, high homogeneity inside the glass, extremely high transmittance, and constant optical properties such as refractive index and Abbe number. Various methods are known for realizing these.

As such a method, a step of melting a glass raw material containing P ₂ O ₅ in a melting furnace heated to 1000 to 1300 ° C., homogenizing the glass raw material, casting the obtained molten glass into a mold, and gradually cooling it. The method which has is known (refer patent document 1-patent document 3).

Japanese Patent Laid-Open No. 06-345481 JP 2002-293572 A JP 2005-206433 A

  However, among the glasses produced by using the methods described in Patent Documents 1 to 3, glass having a large dispersion (small Abbe number) is particularly colored, so that the light beam has a high dispersion. Optical glass with high transmittance cannot be obtained.

  In particular, in the method described in Patent Document 1, it is essential to heat-treat by cooling again to a temperature higher than (glass transition temperature-100 ° C.) after cooling. Moreover, since the method described in Patent Document 1 has a large variation in light transmittance due to heat treatment, long-time heat treatment is required to obtain glass having high light transmittance uniformly. Therefore, even when a short heat treatment is sufficient for the glass, such as when the glass is press-molded or when the strain is removed, it is necessary to perform the heat treatment for a long time. Yes.

Further, in the method described in Patent Document 3, by increasing the Sb ₂ O ₃ component, to some extent the colored glass obtained is reduced. However, when the Sb ₂ O ₃ component is contained according to the method described in the example of Patent Document 3, even if heat treatment such as precision annealing is performed on the obtained glass, the light transmittance is not improved further. However, there is a problem that it cannot be used for an optical instrument that requires high optical performance.

The present invention has been made in view of the above circumstances. In a glass containing a P ₂ O ₅ component, it has a high dispersion, and is less colored without heat treatment and after heat treatment. An object of the present invention is to provide an optical glass manufacturing method capable of obtaining a glass with reduced coloration.

As a result of intensive studies and research to solve the above-mentioned problems, the present inventors are selected from the group consisting of P ₂ O ₅ component, Nb ₂ O ₅ component, TiO ₂ component and WO ₃ component in the molten glass. And a heat treatment is performed while having high dispersion by performing a stirring step of stirring the molten glass at a temperature 0 to 200 ° C. higher than the liquidus temperature of the molten glass. The inventors have found that the transmittance of glass before and after the visible light can be increased, and have completed the present invention. Specifically, the present invention provides the following.

(1) A method for producing an optical glass containing, as essential components, P ₂ O ₅ component and one or more selected from the group consisting of Nb ₂ O ₅ component, TiO ₂ component and WO ₃ component. ,
A step of melting the glass raw material (melting step), a step of clarifying the molten glass raw material (clarification step), a step of stirring the clarified molten glass (stirring step), a step of discharging the stirred molten glass (outflow step), And a step of forming the glass that has flowed out (forming step),
The method which performs the said stirring process at the temperature 0-200 degreeC higher than the liquidus temperature of a molten glass.

  (2) The method according to (1), wherein the outflow step is performed at a temperature 0 to 100 ° C. higher than the liquidus temperature of the molten glass.

  (3) The sum of the time that the molten glass stays in the clarification step and the stirring step is 0.20 times or more and 10.00 times or less the time that the molten glass stays in the melting step (1) or (2) The method described.

  (4) Through the melting step, the refining step, the stirring step, the outflow step, and the forming step, the temperature of the molten glass is adjusted so as not to be higher than the liquid phase temperature by 250 ° C. or more (1) to (3) Any one of the methods.

  (5) The method according to any one of (1) to (4), wherein the temperature of the molten glass is adjusted to less than 1300 ° C. through the melting step, the refining step, the stirring step, the outflow step, and the forming step.

(6) 1% or more selected from the group consisting of 10.0 to 40.0% of P ₂ O ₅ component and Nb ₂ O ₅ component, TiO ₂ component and WO ₃ component in mass% based on oxide The method according to any one of (1) to (5), wherein an optical glass containing 10.0 to 70.0% is produced.

(7) The method according to (6), wherein an optical glass containing at least 30.0% of at least one selected from the group consisting of an Nb ₂ O ₅ component and a TiO ₂ component at an oxide-based mass%.

(8)% by mass based on oxide,
Sb ₂ O ₃ component 0-1.0% and / or SnO ₂ component 0-0.5%
(1) The method in any one of (7) which manufactures the optical glass containing each component of.

(9) The method according to (8), wherein an optical glass having an oxide-based mass sum Sb ₂ O ₃ + SnO ₂ of more than 0% and 1.0% or less is produced.

(10)% by mass based on oxide,
Li ₂ O component 0-20.0% and / or Na ₂ O component 0-35.0% and / or K ₂ O component 0-20.0%
The method according to any one of (1) to (9), wherein an optical glass containing each of the components is produced.

(11) Optical glass in which the mass sum of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) is 35.0% or less in terms of mass% based on oxide. (10) The method of manufacturing.

(12)% by mass based on oxide,
MgO component 0-5.0% and / or CaO component 0-10.0% and / or SrO component 0-10.0% and / or BaO component 0-30.0%
(1) The method in any one of (11) which manufactures the optical glass containing each component of.

  (13) Optical glass in which the mass sum of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is 30.0% or less in terms of mass% based on oxide. (12) The method of manufacturing.

(14)% by mass based on oxide,
Y ₂ O ₃ component 0 to 10.0% and / or La ₂ O ₃ component 0 to 10.0% and / or Gd ₂ O ₃ component 0 to 10.0%
(1) The method in any one of (13) which manufactures the optical glass containing each component of.

(15) An optical component in which the mass sum of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of Y, La, and Gd) is 20.0% or less in terms of mass% based on oxide. The method according to (14), wherein glass is produced.

(16)% by mass based on oxide,
SiO ₂ component 0 to 10.0% and / or B ₂ O ₃ component 0 to 10.0% and / or GeO ₂ component 0 to 10.0% and / or Bi ₂ O ₃ component 0 to 20.0% and / Or ZrO ₂ component 0 to 10.0% and / or ZnO component 0 to 10.0% and / or Al ₂ O ₃ component 0 to 10.0% and / or Ta ₂ O ₅ component 0 to 10.0%
The method according to any one of (1) to (15), wherein an optical glass containing each of the components is produced.

  (17) An optical glass having a refractive index (nd) of 1.70 or more and 2.20 or less and an Abbe number (νd) of 10 or more and 29 or less is described in any one of (1) to (16) Method.

  (18) The method according to any one of (1) to (17), wherein an optical glass having an Abbe number (νd) of less than 19 is produced.

  (19) Spectral transmittance for light having a wavelength of 420 nm is 20% or more before and after a reheating test in which the glass subjected to the forming step is heated to a reheating temperature of (Tg−100) ° C. or more and (Tg + 100) ° C. or less. The method according to any one of (1) to (18), wherein the optical glass is produced.

  (20) An optical instrument using optical glass manufactured by the method according to any one of (1) to (19).

According to the present invention, the molten glass contains a P ₂ O ₅ component and at least one selected from the group consisting of an Nb ₂ O ₅ component, a TiO ₂ component, and a WO ₃ component. By performing the stirring step of stirring the molten glass at a temperature 0 to 200 ° C. higher than the liquidus temperature of the liquid, there is little coloring without performing heat treatment while having desired optical characteristics, particularly high dispersion, and heat treatment. The manufacturing method of the optical glass which can obtain the glass also reduced in coloring after performing can be provided.

The method for producing an optical glass of the present invention includes an optical glass containing, as essential components, a P ₂ O ₅ component and at least one selected from the group consisting of an Nb ₂ O ₅ component, a TiO ₂ component, and a WO ₃ component. A step of melting a glass raw material (melting step), a step of clarifying a molten glass raw material (clarification step), a step of stirring the clarified molten glass (stirring step), and stirring the molten glass. It has the process (outflow process) made to flow out, the process (molding process) of shape | molding the outflowed glass, and performs the said stirring process at 0-200 degreeC temperature higher than the liquidus temperature of a molten glass. Thus, the refractive index and dispersion are enhanced by one or more selected from Nb ₂ O ₅ component, TiO ₂ component and WO ₃ component, but visible light is not subjected to heat treatment by a stirring process at a predetermined temperature. The transmittance of the glass with respect to visible light is increased, and the transmittance of the glass with respect to visible light is increased even after the heat treatment. Therefore, it is possible to obtain a glass that has high dispersion but is less colored without heat treatment and reduced coloration after the heat treatment.

  Hereinafter, embodiments of the method for producing an optical glass of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and appropriate modifications are made within the scope of the object of the present invention. Can be implemented. In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the meaning of invention is not limited.

[Glass raw material]
First, the glass raw material used with the manufacturing method of this invention is demonstrated. The glass raw material used in the present invention contains P ₂ O ₅ and at least one selected from the group consisting of Nb ₂ O ₅ , TiO ₂ and WO ₃ as essential components, and can form glass. It is appropriately selected from the raw materials. Among these, it is preferable to use glass raw materials as described below.

  Hereafter, the composition range of each component which comprises the glass raw material used by this invention is described below. In the present specification, unless otherwise specified, the content of each component is expressed as mass% (mass% based on oxide) with respect to the total mass of the glass raw material having an oxide conversion composition. Here, the “oxide equivalent composition” means that when the oxide, composite salt, metal fluoride, etc. used as a glass raw material in the present invention are all decomposed and changed into an oxide when melted, the generated oxidation It is the composition which described each component contained in a glass raw material by making the total mass of a thing into 100 mass%.

<About essential and optional components>
The P ₂ O ₅ component is a glass forming component and is a component that lowers the melting temperature of glass. In particular, by setting the content of the P ₂ O ₅ component to 10.0% or more, it is possible to increase the stability of the glass and increase the devitrification resistance while increasing the transmittance of the glass with respect to visible light. On the other hand, by setting the content of P ₂ O ₅ component below 40.0%, it is possible to reduce the decrease in the refractive index of the glass. Therefore, the content of the P ₂ O ₅ component with respect to the total mass of the glass raw material having an oxide conversion composition is preferably 10.0%, more preferably 15.0%, and most preferably 20.0%, and preferably Is 40.0%, more preferably 35.0%, and most preferably 30.0%. The P ₂ O ₅ component can be contained in the glass raw material using, for example, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , H ₃ PO _{4 and the} like.

Nb ₂ O ₅ component is a component that raises the refractive index and dispersion of the glass, which is an optional component in the glass material. In particular, by setting the content of the Nb ₂ O ₅ component to 60.0% or less, the stability of the glass can be increased and the devitrification resistance can be increased. Therefore, the content of the Nb ₂ O ₅ component with respect to the total mass of the glass raw material having an oxide conversion composition is preferably 60.0%, more preferably 58.0%, and most preferably 56.0%. Incidentally, resulting is not technical disadvantages even without containing the Nb ₂ O ₅ component, by the content of Nb ₂ O ₅ ingredient 10.0% or more, the desired high refractive index and high dispersion Can be made easier. Accordingly, the content of the Nb ₂ O ₅ component with respect to the total mass of the glass raw material having an oxide equivalent composition is preferably 10.0%, more preferably 20.0%, and most preferably 30.0%. Nb ₂ O ₅ component can contain the glass raw material by using, for example, _Nb 2 _{O 5} or the like.

TiO ₂ component is a component that raises the refractive index and dispersion of the glass, which is an optional component in the glass material. In particular, by setting the content of the TiO ₂ component to 30.0% or less, the stability of the glass can be increased and the devitrification resistance can be increased. Therefore, the content of the TiO ₂ component with respect to the total mass of the glass raw material having an oxide conversion composition is preferably 30.0%, more preferably 28.0%, and most preferably 25.0%. Here, the content of the TiO ₂ component with respect to the total mass of the glass raw material having an oxide conversion composition is preferably 20.0 in that the visible light transmittance of the glass is particularly enhanced while obtaining a high refractive index and dispersion. %, More preferably 19.0%, and most preferably 18.0%. Incidentally, TiO ₂ component is not a technical disadvantage without containing, by containing a TiO ₂ component of 0.1% or more, it is possible to easily obtain the desired high refractive index and high dispersion. Therefore, in this case, the content of the TiO ₂ component with respect to the total mass of the glass raw material having an oxide conversion composition is preferably 0.1%, more preferably 1.0%, and most preferably 2.0%. . Here, from the viewpoint of further improving the chemical durability and dispersion of the glass, the content of TiO ₂ with respect to the total glass mass of the oxide conversion composition is preferably 10.0% or more, more preferably 12.0% or more, Most preferably, it may be 13.0% or more. TiO ₂ component can contain the glass raw material by using, for example, TiO ₂ or the like.

The WO ₃ component is a component that increases the refractive index and dispersion of the glass, and is an optional component in the glass raw material. In particular, by setting the content of the WO ₃ component to 20.0% or less, it is possible to increase the devitrification resistance of the glass and to suppress a decrease in the transmittance of the glass with respect to visible light having a short wavelength. Therefore, the content of the WO ₃ component with respect to the total mass of the glass raw material having an oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. Incidentally, WO ₃ component is not a technical disadvantage without containing, by containing a WO ₃ ingredient 0.1% or more, it is possible to easily obtain the desired high refractive index and high dispersion. Therefore, in this case, the content of the WO ₃ component with respect to the total mass of the glass raw material having an oxide conversion composition is preferably 0.1%, more preferably 1.0%, and most preferably 2.0%. . The WO ₃ component can be contained in the glass raw material using, for example, WO ₃ or the like.

Glass raw material used in the present invention, _Nb 2 _{O 5} ingredient, one or more selected from the group consisting of TiO ₂ component and WO ₃ components. In particular, since the refractive index and dispersion of the glass can be increased by setting the mass sum of one or more selected from the group consisting of Nb ₂ O ₅ component, TiO ₂ component and WO ₃ component to 10.0% or more, It is possible to reduce the size of an optical system using an optical element formed of glass while having a desired high refractive index and high dispersion. On the other hand, since the devitrification resistance of the glass is enhanced by setting the mass sum of one or more of these to 70.0% or less, it is possible to easily obtain a glass having a desired high transmittance. Accordingly, the mass sum of one or more selected from the group consisting of the Nb ₂ O ₅ component, the TiO ₂ component and the WO ₃ component with respect to the total mass of the glass raw material having an oxide equivalent composition is preferably 10.0%, more The upper limit is preferably 15.0%, most preferably 20.0%, preferably 70.0%, more preferably 68.0%, and most preferably 66.0%.

In particular, the present invention is useful when the _Nb 2 _{O 5} component and / or TiO ₂ component using a glass raw material containing more than 30.0%. According to the method of the present invention, Nb ₂ O which is difficult to reduce by simply adding the Sb ₂ O ₃ component and / or the SnO ₂ component described below, while obtaining a desired high refractive index and high dispersion is obtained. _Since the reduction of the _five components and / or the TiO ₂ component is reduced, the coloration of the glass due to this can be reduced. At the same time, the dissolution of melting equipment (especially noble metals such as Pt) that can be generated by adding an excessive amount of Sb ₂ O ₃ component and / or SnO ₂ component is reduced, so that it is difficult to remove glass even by heat treatment. Is reduced. That is, it is possible to obtain an optical glass that has desired optical characteristics, is less colored without heat treatment, and can be further reduced in color by heat treatment. Therefore, the content of at least one of the Nb ₂ O ₅ component and / or the TiO ₂ component is preferably 30.0%, more preferably 35.0%, and most preferably 40.0%.

The Sb ₂ O ₃ component is a component that increases the transmittance of the glass with respect to visible light having a short wavelength and has a defoaming effect when the glass is melted. In particular, by reducing the content of the Sb ₂ O ₃ component to 1.0% or less, the dissolution of dissolution equipment (particularly noble metals such as Pt) due to oxygen released from the Sb ₂ O ₃ component is reduced. It is possible to reduce the coloration of the glass that is difficult to remove even by heat treatment, which occurs due to the dissolution of the equipment. Therefore, the content of the Sb ₂ O ₃ component is preferably 1.0%, more preferably 0.8%, and most preferably 0.6% with respect to the total mass of the glass raw material having an oxide equivalent composition. Here, from the viewpoint of further increasing the light transmittance of the glass with respect to visible light, the content of the Sb ₂ O ₃ component with respect to the total mass of the glass raw material having an oxide conversion composition is preferably less than 0.5%, more preferably. The upper limit is less than 0.4%, and most preferably 0.3%. Sb ₂ O ₃ component is, for example, _{Sb 2 O 3, Sb 2 O} 5, Na may be contained in the glass raw material with _{2 H 2 Sb 2 O 7 ·} 5H 2 O and the like.

The SnO ₂ component is a component that lowers the glass transition point (Tg) and is a component that increases the transmittance of the glass with respect to visible light having a short wavelength. In particular, by setting the content of the SnO ₂ component to 0.5% or less, it is possible to make it difficult to lower the devitrification resistance of the glass. Further, by reducing the content of the SnO ₂ component, it is possible to reduce the coloration of the glass, which is difficult to remove even by heat treatment, which occurs due to dissolution of the melting equipment (especially a noble metal such as Pt). Therefore, the content of the SnO ₂ component with respect to the total mass of the glass raw material having an oxide equivalent composition is preferably 0.5%, more preferably 0.3%, and most preferably 0.1%. SnO ₂ component, for example _SnO, can be contained in the glass raw material with SnO 2, SnO ₃ and the like.

Glass raw material used in the present invention preferably contains at least one selected from the group consisting of Sb ₂ O ₃ component and SnO ₂ component. Thereby, the oxygen deficient state caused by the unnecessary evaporation of the oxygen component contained in the molten glass is easily supplemented by the oxygen atoms released from the Sb ₂ O ₃ component and / or the SnO ₂ component. More specifically, the reduction of transition metal components, particularly Nb ₂ O ₅ component, TiO ₂ component and WO ₃ component contained in the molten glass is reduced by this oxygen atom. That is, the transmittance of the glass with respect to visible light on the short wavelength side, which was apt to decrease due to the reduction of the Nb ₂ O ₅ component, the TiO ₂ component, and the WO ₃ component, without the heat treatment, is increased to reduce coloring. be able to. In addition, when heat-treating the glass, the small amount of the Sb ₂ O ₃ component and / or SnO ₂ component promotes the oxidation of the transition metal component contained in the reduced state in the glass, The glass can be dedistorted, and coloring can be reduced by increasing the transparency of the glass especially for visible light on the short wavelength side. Therefore, the mass sum of one or more selected from the group consisting of the Sb ₂ O ₃ component and the SnO ₂ component with respect to the total mass of the glass raw material having an oxide equivalent composition is preferably more than 0%, more preferably 0.00. The lower limit is 01%, most preferably 0.05%. On the other hand, oxygen released from the Sb ₂ O ₃ component and the SnO ₂ component by reducing the mass sum of one or more selected from the group consisting of the Sb ₂ O ₃ component and the SnO ₂ component to 1.0% or less. Since the dissolution of the melting equipment (particularly noble metals such as Pt) is reduced, coloring that is difficult to remove even by heat treatment of the glass can be reduced. Therefore, the mass sum of one or more selected from the group consisting of the Sb ₂ O ₃ component and the SnO ₂ component with respect to the total mass of the glass raw material having an oxide equivalent composition is preferably 1.0%, more preferably 0.00. The upper limit is 5%, most preferably 0.25%.

The Li ₂ O component is a component that lowers the glass transition point (Tg) and increases devitrification resistance during glass formation, and is an optional component in the glass raw material. In particular, by setting the content of the Li ₂ O component to 20.0% or less, it is possible to easily obtain a desired high refractive index, and it is possible to increase the stability of the glass and reduce the occurrence of devitrification and the like. Therefore, the upper limit of the content of the Li ₂ O component with respect to the total mass of the glass raw material having an oxide equivalent composition is preferably 20.0%, more preferably 18.0%, and most preferably 15.0%. Li ₂ O component can contain in the glass raw material by using, for example, _{Li 2 CO 3, LiNO 3,} LiF and the like.

The Na ₂ O component is a component that lowers the glass transition point (Tg), is a component that increases devitrification resistance during glass formation, and is an optional component in the glass raw material. In particular, by setting the content of the Na ₂ O component to 35.0% or less, it is possible to easily obtain a desired high refractive index, and it is possible to increase the stability of the glass and reduce the occurrence of devitrification and the like. Therefore, the content of the Na ₂ O component with respect to the total mass of the glass raw material having an oxide conversion composition is preferably 35.0%, more preferably 30.0%, and most preferably 25.0%. Incidentally, Na 2 _O but component it is possible to obtain an optical glass having desired properties without containing, by containing a Na 2 _O component 0.1%, the liquidus temperature of the glass is lowered Further, the devitrification resistance of the glass can be further increased. Therefore, in this case, the content of the Na ₂ O component with respect to the total amount of glass in the oxide conversion composition is preferably 0.1%, more preferably 1.0%, and most preferably 2.0%. . Na ₂ O component, for example, _{Na 2 CO 3, NaNO 3,} NaF, be contained in the glass raw material by using the Na 2 SiF ₆ or the like.

The K ₂ O component is a component that lowers the glass transition point (Tg) and increases devitrification resistance during glass formation, and is an optional component in the glass raw material. In particular, by setting the content of the K ₂ O component to 20.0% or less, it is possible to easily obtain a desired high refractive index, and it is possible to increase the stability of the glass and reduce the occurrence of devitrification and the like. Therefore, the content of the K ₂ O component with respect to the total mass of the glass raw material having an oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. Although K 2 _O component it is possible to obtain an optical glass having desired properties without containing the K 2 _O component that contains less than 0.1%, the liquidus temperature of the glass is lowered Further, the devitrification resistance of the glass can be further increased. Therefore, in this case, the content of the K ₂ O component with respect to the total amount of glass in the oxide conversion composition is preferably 0.1%, more preferably 0.15%, and most preferably 0.2%. . K ₂ O component, for example, _{K 2 CO 3, KNO 3,} KF, can be contained in the glass raw material with KHF _2, K ₂ SiF ₆ and the like.

In the present invention, Li 2 _O component, preferably contains Na 2 _O component, and at least one of K _{2 O} component in the glass material, and more preferably contains two or more components. Thereby, since the glass transition point (Tg) of optical glass becomes low, the shaping | molding temperature in press molding can be lowered | hung and the unevenness | corrugation and cloudiness of the surface after performing press molding can be reduced. Moreover, since the liquidus temperature of optical glass becomes low and devitrification resistance is improved, optical glass having a desired light transmittance can be more stably produced.

Further, in this glass material, the mass sum of the content ratio of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) is 35.0% or less. preferable. In particular, when the mass sum of the content ratio of the Rn ₂ O component is 35.0% or less, a decrease in the refractive index of the glass can be suppressed, so that a desired high refractive index can be easily obtained. Moreover, since the stability of the glass is enhanced, the occurrence of devitrification or the like to the glass can be reduced. Therefore, the mass sum of the content ratio of the Rn ₂ O component with respect to the total mass of the glass raw material having an oxide conversion composition is preferably 35.0%, more preferably 30.0%, and most preferably 25.0%. To do. Although Rn 2 _O component it is possible to obtain an optical glass having desired properties without containing, by weight the sum of the content of Rn 2 _O component is 0.1% or more, the glass high While achieving dispersion, the glass transition point (Tg) can be lowered and the water resistance of the glass can be increased. Therefore, the mass sum of the content ratio of the Rn ₂ O component with respect to the total mass of the glass raw material having an oxide conversion composition is preferably 0.1%, more preferably 5.0%, and most preferably 7.0%. To do.

A BaO component is a component which raises the refractive index of glass and improves the devitrification resistance of glass, and is an arbitrary component in a glass raw material. In particular, by setting the content of the BaO component to 30.0% or less, it is possible to easily obtain a desired high refractive index, and it is possible to suppress a decrease in devitrification resistance and chemical durability. Therefore, the content of the BaO component with respect to the total mass of the glass raw material having an oxide equivalent composition is preferably 30.0%, more preferably 28.0%, and most preferably 25.0%. Here, the content of the BaO component with respect to the total mass of the glass raw material having an oxide conversion composition is preferably 17.0%, more preferably 15.5%, in that a glass with particularly large dispersion (small Abbe number) can be obtained. The upper limit is 0%, more preferably less than 7.0%, and most preferably less than 4.5%. In addition, even if it does not contain a BaO component, it is possible to obtain an optical glass having a desired high dispersion, high transparency to visible light, and high devitrification resistance. By doing so, since the liquidus temperature of glass becomes low, the devitrification resistance of glass can be improved more. Accordingly, the content of the BaO component with respect to the total glass mass of the oxide-converted composition in this case is preferably 0.1%, more preferably 0.5%, still more preferably 1.0%, and most preferably 1.5%. % Is the lower limit. Here, from the viewpoint of increasing the detergent resistance of the glass while lowering the liquidus temperature of the glass, the content of the BaO component with respect to the total glass mass of the oxide conversion composition is preferably 7.0%, more preferably The lower limit may be 10.0%, most preferably 12.0%. The BaO component can be contained in the glass raw material using, for example, BaCO ₃ , Ba (NO ₃ ) ₂ , BaF ₂ or the like.

The MgO component is a component that increases the devitrification resistance of the glass by lowering the liquidus temperature of the glass, and is an optional component in the glass raw material. In particular, when the content of the MgO component is 5.0% or less, a desired high refractive index and high dispersion can be easily obtained. Therefore, the content of the MgO component with respect to the total mass of the glass raw material having an oxide equivalent composition is preferably 5.0%, more preferably 4.0%, and most preferably 3.0%. The MgO component can be contained in the glass raw material using, for example, MgCO ₃ , MgF ₂ or the like.

A CaO component is a component which raises the devitrification resistance of glass by lowering | hanging the liquidus temperature of glass, and is an arbitrary component in a glass raw material. In particular, by setting the content of the CaO component to 10.0% or less, it is possible to easily obtain a desired high refractive index and high dispersion, and it is possible to suppress a decrease in devitrification resistance and chemical durability. Therefore, the content of the CaO component with respect to the total mass of the glass raw material having an oxide equivalent composition is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. CaO component can contain in the glass raw material by using, for example, a CaCO _3, CaF ₂ and the like.

The SrO component is a component that increases the devitrification resistance of the glass by lowering the liquidus temperature of the glass, and is an optional component in the glass raw material. In particular, by setting the content of the SrO component to 10.0% or less, it is possible to easily obtain a desired high refractive index and high dispersion, and it is possible to suppress a decrease in devitrification resistance and chemical durability. Therefore, the content of the SrO component with respect to the total mass of the glass raw material having an oxide equivalent composition is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. The SrO component can be contained in the glass raw material using, for example, Sr (NO ₃ ) ₂ , SrF ₂ or the like.

  In this glass raw material, the mass sum of the content of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably 30.0% or less. Thereby, since the fall of the refractive index and dispersion | distribution by RO component is suppressed, it can make it easy to obtain desired high refractive index and high dispersion | distribution. Therefore, the upper limit of the mass sum of the RO component content with respect to the total mass of the glass raw material having an oxide equivalent composition is preferably 30.0%, more preferably 25.0%, and most preferably 20.0%. An optical glass having desired characteristics can be obtained without containing any RO component, but the liquid phase temperature of the glass is lowered by containing at least one of the RO components in an amount of 0.1% or more. Therefore, the devitrification resistance of the glass can be further increased. Therefore, in this case, the mass sum of the content of the RO component with respect to the total mass of the glass raw material having an oxide conversion composition is preferably 0.1%, more preferably 0.5%, and most preferably 1.0%. And

The La ₂ O ₃ component, the Gd ₂ O ₃ component, and the Y ₂ O ₃ component are components that increase the refractive index of the glass and improve the chemical durability of the glass, and are optional components in the glass raw material. In particular, by increasing the content of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of Y, La, and Gd) to a predetermined level or less, the Abbe number is increased by the Ln ₂ O ₃ component Therefore, desired high dispersion can be easily obtained. Further, by setting the content of Ln ₂ O ₃ component to a predetermined or less, the liquidus temperature of the glass is lowered, it is possible to increase the light transmittance to increase the devitrification resistance of the glass. Accordingly, the content of each of the Ln ₂ O ₃ components with respect to the total mass of the glass raw material having an oxide conversion composition is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. To do. Further, the total content of the Ln ₂ O ₃ component with respect to the total mass of the glass raw material having an oxide conversion composition is preferably 20.0%, more preferably 18.0%, and most preferably 15.0%. To do. The Ln ₂ O ₃ component uses, for example, Y ₂ O ₃ , YF ₃ , La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ O (X is an arbitrary integer), Gd ₂ O ₃ , GdF _{3 and the} like. Can be contained in glass raw materials.

The SiO ₂ component is a component that reduces coloring and increases the transmittance for short-wavelength visible light, and lowers the liquidus temperature of the glass to increase the devitrification resistance of the glass, and is an optional component in the glass raw material. is there. In particular, by setting the content of the SiO ₂ component to 10.0% or less, a decrease in the refractive index due to the SiO ₂ component can be suppressed, so that a desired high refractive index can be easily obtained. Accordingly, the content of the SiO ₂ component with respect to the total mass of the glass raw material having an oxide conversion composition is preferably 10.0%, more preferably 8.0%, and even more preferably 5.0%, and most preferably Less than 2.0%. SiO ₂ component, for example, contained in the glass raw material with _{SiO 2, K 2 SiF 6,} Na 2 SiF 6 or the like.

The B ₂ O ₃ component is a component that lowers the liquidus temperature of the glass and increases the devitrification resistance, and is an optional component in the glass raw material. In particular, by setting the content of the B ₂ O ₃ component to 10.0% or less, a decrease in the refractive index due to the B ₂ O ₃ component can be suppressed, so that a desired high refractive index can be easily obtained. Therefore, the content of the B ₂ O ₃ component is preferably 10.0%, more preferably 8.0%, and most preferably 5.0% with respect to the total mass of the glass raw material having an oxide equivalent composition. . B ₂ O ₃ component is, for example, _{H 3 BO 3, Na 2 B} 4 O 7, Na 2 B 4 O 7 · 10H 2 O, can be contained in the glass raw material by using BPO ₄ and the like.

The GeO ₂ component is a component that increases the refractive index of the glass and lowers the liquidus temperature of the glass to increase the devitrification resistance of the glass, and is an optional component in the glass raw material. In particular, by setting the content of the GeO ₂ component is 10.0% or less, can reduce material costs of the glass. Therefore, the upper limit of the content of the GeO ₂ component with respect to the total mass of the glass raw material having an oxide equivalent composition is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. GeO ₂ component can contain the glass raw material by using, for example, GeO ₂ or the like.

Bi ₂ O ₃ component, increasing the refractive index of the glass, or to enhance the dispersion of the glass, which is an optional component in the glass material. In particular, by setting the content of the Bi ₂ O ₃ component to 20.0% or less, the liquidus temperature of the glass can be lowered to suppress a decrease in devitrification resistance. Can be suppressed. Therefore, the content of the Bi ₂ O ₃ component with respect to the total mass of the glass raw material having an oxide equivalent composition is preferably 20.0%, more preferably 15.0%, and even more preferably less than 10.0%. And most preferably less than 5.0%.

The ZrO ₂ component is a component that increases the transmittance for visible light and increases the devitrification resistance of the glass to increase the devitrification resistance of the glass, and is an optional component in the glass raw material. In particular, by making the content of the ZrO ₂ component 10.0% or less, a decrease in the refractive index due to the ZrO ₂ component can be suppressed, so that a desired high refractive index can be easily obtained. Therefore, the content of the ZrO ₂ component with respect to the total mass of the glass raw material having an oxide equivalent composition is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. ZrO ₂ component can contain in the glass raw material by using, for example, a _ZrO 2, ZrF _4, and the like.

A ZnO component is a component which raises the devitrification resistance of glass by lowering | hanging the liquidus temperature of glass, and is an arbitrary component in a glass raw material. In particular, the desired high refractive index and high dispersion can be easily obtained by setting the content of the ZnO component to 10.0% or less. Accordingly, the content of the ZnO component with respect to the total mass of the glass raw material having an oxide equivalent composition is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. ZnO components are, for example ZnO, can be contained in the glass raw material with ZnF ₂ and the like.

The Al ₂ O ₃ component is a component that improves the chemical durability of the glass and increases the viscosity when the glass is melted, and is an optional component in the glass raw material. In particular, by making the content of the Al ₂ O ₃ component 10.0% or less, it is possible to weaken the devitrification tendency of the glass while improving the meltability of the glass. Therefore, the upper limit of the content of the Al ₂ O ₃ component with respect to the total mass of the glass raw material having an oxide conversion composition is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. The Al ₂ O ₃ component can be contained in the glass raw material using, for example, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ or the like as the raw material.

Ta ₂ O ₅ component is a component that raises the refractive index of the glass, which is an optional component in the glass material. In particular, by making the content of the Ta ₂ O ₅ component 10.0% or less, the glass can be made hard to devitrify. Therefore, the content of the Ta ₂ O ₅ component with respect to the total mass of the glass raw material having an oxide equivalent composition is preferably 10.0%, more preferably 8.0%, and most preferably 4.0%. The Ta ₂ O ₅ component can be contained in the glass raw material using, for example, Ta ₂ O ₅ as a raw material.

<About ingredients that should not be included>
Other components can be added to the glass raw material as needed within a range that does not impair the properties of the glass. However, each transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo, excluding Ti, Nb, and W, tends to cause glass coloring, and the light transmittance of the present invention. It has the property of diminishing effects. Therefore, it is preferable to reduce the content of these transition metal components, and it is more preferable that they are not substantially contained.

  In addition, lead compounds such as PbO and components of Th, Cd, Tl, Os, Be, and Se tend to be refrained from being used as harmful chemical substances in recent years. In addition, measures for environmental measures are required until disposal after commercialization. Therefore, when importance is placed on the environmental impact, it is preferable not to substantially contain them except for inevitable mixing. As a result, the optical glass is substantially free of substances that pollute the environment. Therefore, the optical glass can be manufactured, processed, and discarded without taking special environmental measures.

[Production of optical glass]
In the production method of the present invention, an optical glass is produced by performing a melting step, a clarification step, a stirring step, an outflow step, and a forming step on the glass raw material.

  Here, in the melting step, the clarification step, the stirring step, and the outflow step, it is preferable that the raw glass is sequentially supplied to the melting tank, the clarification tank, and the stirring tank, and then discharged from the outflow means provided in the stirring tank. Thereby, while the optical glass is continuously produced, oxygen atoms contained in the raw glass and / or molten glass are appropriately discharged, so that they are included in melting equipment such as a melting tank, a clarification tank, and a stirring tank. Elution of components (especially noble metals such as Pt) is reduced. That is, an optical glass having a high light transmittance can be continuously produced, and the life of the melting equipment can be extended, so that the production efficiency of the optical glass having desired optical characteristics and shape can be increased.

  On the other hand, it is also preferable to perform two or more processes in the same tank among a melting process, a clarification process, and a stirring process, or to perform one process in a plurality of tanks. Thereby, since the capacity | capacitance of each tank will not be proportional to the time which each process requires, with respect to the raw material glass and / or molten glass of the optimal capacity | capacitance according to each process, a melting process, clarification over predetermined time mentioned later A process and a stirring process can be performed. Among these, it is more preferable to perform the melting step, the clarification step, and the stirring step in the same tank after the glass raw material is supplied to the tank, and to let the molten glass flow out from this tank. Thereby, since the optical glass according to the capacity | capacitance of a tank is produced, a small amount and many types of optical glass can be produced. In addition, the melting tank, the clarification tank, and the stirring tank in this specification are the layers which perform a melting process, a clarification process, and a stirring process, and the tank which serves as two or more of these shall also be included.

[Melting process]
In the melting step, the above glass raw material supplied to the melting tank is melted to form molten glass. Here, the method for forming the molten glass is appropriately selected depending on the properties of the glass raw material.

For example, it is preferable to melt a batch made of a glass raw material that has not been vitrified by a single heating operation and simultaneously perform vitrification of the raw glass and formation of molten glass. This
By forming the molten glass with a short heating time, the contact time between the glass raw material and the melting tank is reduced. Therefore, coloring due to elution of components (particularly noble metals such as Pt) contained in the melting tank into the glass can be reduced.

  On the other hand, it is also preferable to melt a cullet obtained by cooling one or more glass raw materials after melting and at least partially vitrifying them with other glass raw materials or other cullet. Thereby, it becomes easy to proceed to vitrification of the glass raw material multiple times, and by reducing the generation rate of bubbles from the raw glass or molten glass, soaking of the raw glass or molten glass is enhanced, An optical glass having a uniform composition and characteristics can be obtained.

  The melting temperature at which the raw glass is melted in the melting step is appropriately selected from temperatures at which the raw glass can be melted and vitrified after cooling. More specifically, the melting temperature is preferably 1000 ° C. or higher, more preferably 1030 ° C. or higher, and most preferably 1050 ° C. or higher. Thereby, since raw material glass becomes easy to be melt | dissolved and it becomes difficult to produce unmelted residue, a homogeneous optical glass can be obtained after the stirring process mentioned later. On the other hand, the melting temperature is preferably less than 1300 ° C, more preferably less than 1250 ° C, and most preferably less than 1240 ° C. Thereby, since the elution to the molten glass of the component contained in a melting tank is reduced, coloring of the glass by these components can be reduced. The melting temperature is preferably less than (liquid phase temperature + 250 ° C.), more preferably less than (liquid phase temperature + 220 ° C.) in relation to the liquid phase temperature of the glass obtained, Most preferably, it is less than (phase temperature + 200 ° C.). Thereby, since crystallization of the glass component in the molten glass is reduced, it is possible to make it difficult to reduce the visible light transmittance of the optical glass in that devitrification of the obtained glass can be reduced.

  In the present specification, “melting temperature” refers to the average of the temperature of the glass raw material in the upper part of the melting tank and the temperature of the glass raw material in the lower part of the melting tank. Here, the temperature of the glass raw material in the upper part and the lower part of a melting tank can be calculated | required, for example using the thermocouple provided in the inside of a melting tank, or a wall surface. Moreover, you may obtain | require the temperature of the glass raw material in the upper part of a melting tank using a radiation thermometer.

  Moreover, the liquid phase temperature of the glass obtained is formed from a glass having the same composition as the raw glass, and a glass sample crushed into granules having a diameter of about 2 mm is placed on a platinum plate and has a temperature gradient of 800 ° C. to 1220 ° C. It is measured by observing the presence or absence of crystals in the glass with a microscope with a magnification of 80 times after holding for 30 minutes in a heated furnace, and is the lowest at which no crystal is observed in the glass and devitrification does not occur. Calculated from temperature.

  The melting time for melting the raw glass in the melting step is appropriately selected depending on the shape and capacity of the melting tank, the type of heating means, and the like. More specifically, the melting time of the raw glass is preferably 0.01 hours or more, more preferably 0.1 hours or more, and most preferably 0.2 hours or more. This makes it difficult for the raw glass to remain melted, so that a homogeneous optical glass can be obtained after the stirring step described later. On the other hand, the melting time is preferably 10 hours or less, more preferably 8 hours or less, and most preferably 7 hours or less. Thereby, the contact time between the glass raw material and the melting tank is shortened, and the elution of the components contained in the melting tank into the glass raw material is reduced, so that the coloring of the glass due to the elution of these components can be reduced.

In addition, “melting time” in the specification of the present application indicates an average time for the raw glass to stay in the melting tank. For example, when the supply and discharge speeds of the raw glass are constant, when the supply of the glass raw material to the melting tank is started (when the raw glass is heated to the melting temperature after the supply of the raw glass, the temperature of the supplied glass raw material Δt _ab [h], from the time when the glass material reaches the above melting temperature) to the time when the discharge of the glass raw material from the melting tank (or the time when the process proceeds to the clarification step described later) starts to the glass raw material melting tank Discharging from the glass raw material melting tank is completed from the time when the supply of the glass is finished (when the raw glass is heated to the melting temperature after the raw glass is supplied, the temperature of the supplied glass raw material reaches the melting temperature described above) The melting time Δt ₁ [h] can be obtained from the following equation (1), where Δt _cd [h] is the time until the time to perform (or the time to shift to the clarification step described later).

[Clarification process]
In the clarification step, the glass raw material melted in the melting step is retained for a predetermined time to be clarified. As a result, the vitrification of the glass raw material is further promoted, and excess gas components generated by vitrification, for example, oxygen atoms and hydrogen atoms become bubbles and are discharged from the melt at an appropriate rate. Therefore, it is possible to increase the soaking property of the molten glass, obtain an optical glass having a uniform composition and characteristics, and reduce the devitrification of the glass. Therefore, it is possible to make it difficult to reduce the light transmittance of visible light of the optical glass. The “molten glass” in the present specification includes not only a molten glass material after vitrification but also a molten glass material before vitrification.

  The clarification temperature at which the molten glass is clarified in the clarification step is appropriately selected from the temperatures at which the vitrification can proceed and the bubbles can be precipitated, but the viewpoint of efficiently removing the bubbles while increasing the efficiency of vitrification Therefore, the temperature is preferably higher than the melting temperature. More specifically, the fining temperature in the fining step is preferably 1020 ° C. or higher, more preferably 1050 ° C. or higher, and most preferably 1080 ° C. or higher. Thereby, while the efficiency of vitrification of the glass raw material is increased, the viscosity of the molten glass is reduced and the bubbles are likely to float on the molten glass, so that it is possible to easily obtain an optical glass with less devitrification and coloring. . On the other hand, the fining temperature is preferably less than 1300 ° C, more preferably less than 1250 ° C, and most preferably less than 1240 ° C. Further, this fining temperature is preferably less than (liquid phase temperature + 250 ° C.), more preferably less than (liquid phase temperature + 220 ° C.) in relation to the liquid phase temperature of the glass obtained, Most preferably, it is less than (phase temperature + 200 ° C.). By setting the clarification temperature to a predetermined temperature or less, the interaction between the molten glass and the clarification tank, for example, the elution of the components contained in the clarification tank into the glass raw material is reduced, so the coloring of the glass due to the eluted components is reduced. it can.

  In addition, the “clarification temperature” in the present specification refers to the average of the temperature of the molten glass in the upper part of the clarification tank and the temperature of the molten glass in the lower part of the clarification tank. Here, the temperature of the molten glass in the upper part and the lower part of the clarification tank can be determined using, for example, a thermocouple provided in the clarification tank or on the wall surface. Moreover, you may obtain | require the temperature of the molten glass in the upper part of a clarification tank using a radiation thermometer.

  The clarification time for retaining the molten glass in the clarification step is preferably 0.01 hours or more, more preferably 0.2 hours or more, and most preferably 0.3 hours or more. Thereby, since vitrification of molten glass is advanced, optical glass with little devitrification can be obtained. On the other hand, the clarification time is preferably 10 hours or less, more preferably 8 hours or less, and most preferably 5 hours or less. Thereby, since the contact time between the molten glass containing a large amount of gas components and the clarification tank is reduced, elution of the components of the clarification tank can be reduced, and an optical glass with less coloring can be easily obtained.

In addition, the “clarification time” in the specification of the present application indicates an average time during which the molten glass stays in the clarification tank. For example, when the supply speed of the raw glass and the discharge speed of the molten glass are constant, the clarification of the molten glass from the time when the supply of the glass raw material to the clarification tank is started (or when the transition from the melting process to the clarification process). Δt _ab ′ [h], the time to start discharging from the tank (or time to shift to the stirring process described later), the time to end the supply of the glass raw material to the melting tank (or the melting process described above) Clarification time Δt when the time from the time when the discharge of the molten glass from the clarification tank to the time when the discharge from the clarification tank is completed (or the time when the process proceeds to the stirring step described later) is Δt _cd '[h]. ₂ [h] is obtained from the following equation (2).

[Stirring step]
In the stirring step, the clarified molten glass is stirred. Thereby, the formation of bubbles from the gas component from the molten glass is promoted, so that the removal of the gas component from the molten glass is promoted and the uniformity of the composition of the molten glass is enhanced. Therefore, coloring due to elution of components such as precious metals contained in the melting equipment into the glass can be reduced, and an optical glass with less precipitation of gas components can be obtained. Therefore, the light transmittance of visible light of the optical glass can be increased.

  The stirring means for stirring the molten glass in the stirring step is appropriately selected depending on the viscosity of the molten glass, the shape of the stirring tank, and the like. Here, it is preferable to use the stirring means provided so that the stirring means may include the bottom face and / or the vicinity of the wall surface of the stirring tank. Thereby, the flow of the molten glass is formed along the bottom surface and the wall surface of the stirring tank, so that the bubbles are efficiently removed from the bottom surface and the wall surface of the stirring tank in which bubbles are easily formed. Therefore, the elution to the molten glass of the component contained in a stirring tank can be reduced, and coloring of glass can be reduced. Among these, it is particularly preferable that the stirring means is provided along the bottom surface of the stirring tank. Accordingly, when the molten glass is discharged from the stirring tank, the molten glass is stirred until immediately before the stirring tank becomes empty, and the formation of bubbles is reduced. Therefore, in the outflow process described later, even when all of the molten glass in the stirring tank flows out, elution of the components in the stirring tank can be reduced until just before the stirring tank is empty, so at the start and end of the outflow process. The light transmittance of the optical glass can be made closer.

The stirring temperature at which the molten glass is stirred in the stirring step is adjusted to (liquid phase temperature + 200 ° C.) or lower with respect to the liquid phase temperature of the obtained glass. As a result, the unnecessary evaporation of the oxygen component contained in the molten glass is reduced, so that it is also removed by heat treatment by elution of components (particularly noble metal components such as Pt) contained in the melting equipment caused by excess oxygen atoms. It is possible to reduce discoloration due to reduction of the Nb ₂ O ₅ component, the TiO ₂ component and / or the WO ₃ component, which can bring about particularly high dispersion while reducing the discoloration of the glass which is difficult to achieve. At the same time, since the concentration of the oxygen component contained in the molten glass is not necessarily dependent on the Sb ₂ O ₃ component and / or the SnO ₂ component, when the glass is heat-treated, it is reduced to the glass. The oxidation of the contained Nb ₂ O ₅ component, TiO ₂ component and / or WO ₃ component can be promoted. That is, without performing heat treatment, it is possible to increase the transmittance of the glass for light on the short wavelength side of visible light, and by performing the heat treatment, the transmittance of the glass for light on the short wavelength side of visible light can be further increased. Can be increased. Here, the stirring temperature in the stirring step is more preferably adjusted to (liquid phase temperature + 180 ° C.) or lower, most preferably (liquid phase temperature + 170 ° C.) or lower. On the other hand, this stirring temperature is set to the liquid phase temperature or higher of the glass to be obtained, more preferably (liquid phase temperature + 10 ° C.) or higher, and most preferably (liquid phase temperature + 20 ° C.) or higher. Thereby, crystallization of the glass component contained in the molten glass is reduced, and devitrification is less likely to occur in the obtained glass, so that an optical glass having high stability can be obtained. At the same time, the oxygen component contained in the molten glass easily evaporates moderately, so that it can also be removed by heat treatment by elution of components (particularly noble metal components such as Pt) contained in the melting equipment caused by excess oxygen atoms. Difficult discoloration of glass can be reduced.

Since this stirring temperature should just be in the temperature range which can adjust the oxygen component contained in a molten glass, it does not necessarily need to be constant temperature over the predetermined | prescribed time which performs a stirring process. At this time, the highest temperature among the stirring temperatures is preferably a temperature equal to or lower than the clarification temperature from the viewpoint of reducing excessive vaporization of gas components, particularly oxygen components contained in the molten glass. The temperature may be higher than the fining temperature in order to promote the discharge of the components. That is, the highest temperature among the stirring temperatures is preferably less than 1300 ° C, more preferably less than 1250 ° C, and most preferably less than 1240 ° C. Thereby, the excessive evaporation of the oxygen component contained in the molten glass and the elution of the components contained in the melting equipment into the molten glass are reduced, so that the transition metal component, particularly Nb ₂ O ₅ contained in the molten glass is reduced. Discoloration due to reduction of components, TiO ₂ component and / or WO ₃ component, and discoloration due to elution of components contained in dissolution equipment are reduced, so that visible light transmittance is higher without heat treatment and heat treatment is performed. By doing so, an optical glass capable of further increasing the transmittance of visible light can be obtained.

  On the other hand, the lowest temperature among the stirring temperatures is preferably 1000 ° C. or higher, more preferably 1050 ° C. or higher, and most preferably 1100 ° C. or higher. Thereby, since the viscosity of a molten glass does not become high too much, the load concerning a stirring means is reduced, becoming easy to remove a bubble. Therefore, the stirring process can be performed efficiently.

  In addition, it is preferable to use the average temperature in the several location of the molten glass which retains in a stirring tank in a stirring process as "stirring temperature" in this specification. More specifically, it is preferable to use the average of the temperature of the molten glass in the upper part of the stirring tank and the temperature of the molten glass in the lower part of the stirring tank. As a result, even when a temperature gradient is generated inside the molten glass, it is easy to suppress the coloring of the molten glass and the crystallization of the glass component. can do. Here, the temperature of the molten glass in the upper part and the lower part of the stirring tank can be determined using, for example, a thermocouple provided in the stirring tank or on the wall surface. Moreover, the temperature of the molten glass in the upper part of a stirring tank can also be calculated | required using a radiation thermometer.

  The stirring time for stirring the molten glass in the stirring tank is preferably 0.01 hours or more, more preferably 0.2 hours or more, and most preferably 0.3 hours or more. Thereby, since the gas component contained in the molten glass is easily removed, elution of the component contained in the melting equipment into the glass can be reduced, and the light transmittance of the optical glass can be increased. Moreover, since the removal of the bubbles from the molten glass proceeds, the bubbles can hardly be left in the optical glass. On the other hand, the stirring time is preferably 10 hours or less, more preferably 8 hours or less, and most preferably 5 hours or less. Thereby, the excessive removal of the oxygen component contained in molten glass and the elution to the molten glass of the component contained in melting | dissolving equipment are suppressed, and coloring of glass is reduced. Therefore, it is possible to easily obtain an optical glass that has both the small number of bubbles and the high light transmittance.

In addition, the “stirring time” in the specification of the present application indicates an average time during which the molten glass is stirred by the stirring means. For example, when the supply speed of the molten glass to the stirring tank and the discharge speed from the stirring tank are equal and constant, and the stirring of the molten glass is always performed in the stirring tank, the volume of the molten glass stored in the stirring tank is When V [m ³ ], the supply rate and the discharge rate of the molten glass supplied to and discharged from the stirring tank are v [m ³ / h], the stirring time Δt ₃ [h] is approximately the following equation (3): More demanded.
Δt ₃ = V / v (3)
In addition, when the molten glass does not flow into the stirring tank and the molten glass is not discharged from the stirring tank during the stirring step, the time when the stirring of the molten glass by the stirring means is started is represented by t _S. when t _G when to terminate the agitation of the molten glass by a stirring time Δt 3 _[h] is determined from the following equation (4).
Δt ₃ = t _G -t _S (4)

In the production method of the present invention, the sum (Δt ₁ + Δt ₂ ) of the time during which the molten glass stays in the clarification step and the stirring step is 0.20 times or more and 10.00 times the time Δt ₃ during which the molten glass stays in the melting step. The following is preferable. In particular, by making the sum of the refining time and the stirring time 0.20 times or more of the melting time, it is easy to remove excess gas components, particularly oxygen components, contained in the molten glass. In particular, coloring due to elution of noble metals such as Pt into the glass can be reduced. On the other hand, by making the sum of the clarification time and the stirring time less than or equal to 10.00 times the melting time, it becomes difficult to remove excess oxygen components from the molten glass, so the transition metal component contained in the molten glass, particularly Coloring due to reduction of Nb ₂ O ₅ component, TiO ₂ component and / or WO ₃ can be reduced. Therefore, by making the sum of the clarification time and the stirring time within a predetermined range with respect to the melting time, the visible light transmittance is higher without performing heat treatment, and the visible light transmittance is increased by performing heat treatment. An optical glass that can be further increased can be obtained. The sum of clarification time and stirring time in the production method of the present invention is preferably 0.20 times the melting time, more preferably 0.30 times the melting time, most preferably 0.40 times the melting time, The upper limit is preferably 10.00 times the melting time, more preferably 9.50 times the melting time, and most preferably 9.00 times the melting time.

[Outflow process]
In the outflow step, the stirred molten glass is caused to flow out of the stirring tank. Thereby, since a flow of molten glass is formed, an optical glass having a high visible light transmittance can be continuously and / or intermittently formed into a desired shape.

  Here, as the outflow means for flowing out the molten glass in the outflow process, for example, an outflow pipe extending from the stirring tank can be used. Thereby, since the flow of the molten glass with a predetermined flow velocity is formed, the dimensional accuracy of the optical glass molded in the molding process can be further increased.

  The outflow temperature at which the molten glass is caused to flow out in the outflow step is preferably lower than the fining temperature and the stirring temperature in that excessive evaporation of the oxygen component from the molten glass can be reduced. More specifically, the outflow temperature in the outflow step is preferably less than 1200 ° C, more preferably less than 1180 ° C, and most preferably less than 1150 ° C. In addition, this outflow temperature is preferably (liquid phase temperature + 100 ° C.) or less, and more preferably less than (liquid phase temperature + 90 ° C.) in terms of the temperature relative to the liquid phase temperature of the obtained glass. It is preferably less than (liquid phase temperature + 80 ° C.). By setting the outflow temperature below the specified temperature, evaporation of excess oxygen components from the molten glass before outflow and elution of the components contained in the melting equipment into the molten glass are reduced. Optical glass can be formed. On the other hand, this outflow temperature is preferably set to a temperature higher than the liquid phase temperature of the obtained glass, more preferably (liquid phase temperature + 10 ° C.) or higher, and most preferably (liquid phase temperature + 15 ° C.) or higher. Thereby, crystallization of the glass component contained in the molten glass is reduced, and devitrification is less likely to occur in the obtained glass, so that an optical glass having high stability can be obtained. The outflow temperature is preferably 1020 ° C or higher, more preferably 1050 ° C or higher, and most preferably 1060 ° C or higher. As a result, desired fluidity is ensured in the fluidized glass, and the flow rate of the molten glass becomes substantially constant, so that clogging of the molten glass in the outflow means and molding failure of the optical glass can be reduced.

  In addition, the “outflow temperature” in the present specification refers to the temperature of the molten glass in the outflow means. Here, the temperature of the molten glass in the outflow means can be obtained by using, for example, a thermocouple or a radiation thermometer provided on the wall surface of the outflow means.

[Molding process]
In the forming step, molten glass supplied at a predetermined flow rate is formed. As a result, the molten glass is molded into a predetermined shape by a molding die or the like and loses fluidity, while the evaporation of gas components from the molten glass is stopped, so that the optical glass capable of further increasing the transmittance of visible light. Can be obtained.

  Here, the molding temperature at which the molten glass is molded in the molding step is the same as the outflow temperature described above, in that it can reduce the evaporation of excess oxygen components and the elution of components contained in the melting equipment. The following temperature is preferable. More specifically, it is preferably less than 1200 ° C, more preferably less than 1150 ° C, and most preferably 1100 ° C or less. In addition, this outflow temperature is preferably less than (liquid phase temperature + 250 ° C.) and more preferably less than (liquid phase temperature + 220 ° C.) in terms of the temperature relative to the liquid phase temperature of the glass obtained. It is preferably less than (liquid phase temperature + 200 ° C.). By setting the molding temperature to a predetermined temperature or less, evaporation of oxygen components from the molten glass and elution of components contained in the melting equipment are reduced, and a rapid temperature at which the molten glass and the mold come into contact with each other. Since the fluctuation is reduced, the visible light transmittance is higher without heat treatment, and the visible light transmittance can be further increased by heat treatment, and an optical glass with few cracks is obtained. Can do. On the other hand, this molding temperature is preferably set to the liquid phase temperature or higher of the glass to be obtained, more preferably (liquid phase temperature + 10 ° C.) or higher, and most preferably (liquid phase temperature + 15 ° C.) or higher. As a result, crystallization of the glass component contained in the molten glass is reduced, and devitrification is unlikely to occur in the obtained glass, so that an optical glass having a low visible light transmittance and high stability is obtained. Can do. The outflow temperature is preferably 900 ° C. or higher, more preferably 1000 ° C. or higher, and most preferably 1050 ° C. or higher. Thereby, since desired fluidity | liquidity is ensured to a fluid glass, the shaping | molding defect of an optical glass can be reduced.

  The “molding temperature” in this specification refers to the temperature at which the molten glass comes into contact with a molding means such as a mold. Here, the temperature at which the molten glass comes into contact with a forming means such as a mold can be determined using, for example, a radiation thermometer.

  As described above, in the production method of the present invention, the temperature of the molten glass is preferably adjusted to less than 1300 ° C. through the melting step, the clarification step, the stirring step, the outflow step, and the forming step, and is 250 ° C. higher than the liquidus temperature. It is preferable to adjust so that it does not become higher. As a result, excessive evaporation of the oxygen component from the molten glass is reduced, so that the visible light transmittance of the glass can be increased without performing heat treatment, and the heat treatment can be performed with respect to the visible light of the glass. It becomes possible to further increase the transmittance. Therefore, the temperature of the molten glass in the production method of the present invention is preferably adjusted to be less than 1300 ° C, more preferably less than 1250 ° C, and most preferably less than 1240 ° C. Further, from the viewpoint of the temperature relative to the liquidus temperature of the glass obtained, the temperature of the molten glass in the production method of the present invention is preferably less than (liquidus temperature + 250 ° C), and (liquidus temperature + 220 ° C). ) Is more preferable, and most preferably (liquid phase temperature + 200 ° C.).

[Optical glass]
The optical glass produced according to the present invention needs to have a high refractive index (n _d ) and a high dispersion. In particular, the refractive index ( _nd ) of the optical glass is preferably 1.75, more preferably 1.80, most preferably 1.90, and preferably 2.30, more preferably 2.20, most preferably 1.90. The upper limit is preferably 2.10. Further, the Abbe number (ν _d ) of the optical glass is preferably 29, more preferably 25, still more preferably 22, and most preferably 19. As a result, the degree of freedom in optical design is increased, and a large amount of light refraction can be obtained even if the device is made thinner. In particular, the method of the present invention is useful in producing optical glass having an Abbe number (νd) of less than 19, more specifically less than 18.5, more specifically less than 18. According to the method of the present invention, the coloration of the glass due to the heat treatment of the glass is reduced while the coloration of the glass generated when forming the glass having high dispersion is reduced. Therefore, it is possible to obtain an optical glass that can reduce coloration before and after the heat treatment while having a desired high dispersion. In addition, the lower limit of the Abbe number (ν _d ) of the optical glass is not particularly limited and is appropriately determined according to the technical level. The Abbe number (ν _d ) of the optical glass obtained by the present invention is approximately It is often 10 or more, specifically 12 or more, and more specifically 15 or more.

  Moreover, it is preferable that the optical glass produced by this invention has little coloring. In particular, the optical glass produced according to the present invention is a sample having a thickness of 420 nm and a light having a wavelength of 420 nm before and after the reheating test in which the temperature is raised to a reheating temperature of (Tg−100) ° C. to (Tg + 100) ° C. Is preferably 20% or more, more preferably 25% or more, and most preferably 30% or less. Thus, when the optical element is produced by cold working such as polishing without heat-treating the formed glass, and the optical element is produced by reheating (heat treatment) the glass for precision annealing or press molding. In each case, transparency to visible light is increased and coloring is reduced. That is, various processing steps can be performed on the optical glass to produce an optical element such as a lens having desired optical characteristics. The lower limit of the spectral transmittance of the optical glass with respect to the light having a wavelength of 420 nm is not particularly limited, and is appropriately determined according to the technical level. In many cases, the lower limit of the rate is approximately 80% or less, specifically 75% or less, and more specifically 70% or less.

  Moreover, it is more preferable that the optical glass produced according to the present invention has little color change when reheated (heat treatment). In particular, the optical glass produced according to the present invention has a spectroscopic analysis for light having a wavelength of 420 nm with a sample having a thickness of 10 mm before and after a reheating test in which the temperature is raised to a reheating temperature of (Tg-100) ° C. or higher and (Tg + 100) ° C. or lower. The difference in transmittance is preferably 50% or less, more preferably 30%, and most preferably 20% or less. Thereby, the time required for reheating the glass can be shortened, and when the reheating is performed, color unevenness can hardly be caused in the optical glass. The optical glass produced by the production method of the present invention has already increased the light transmittance before the reheating test, so the time for reheating the glass is shortened or the reheating is substantially performed. Even if it does not carry out automatically, the transparency of glass with respect to visible light can be improved and optical glass with little coloring can be obtained.

  Here, the optical glass produced according to the present invention may be heated to the above-described reheating temperature simultaneously with, for example, precision annealing or press molding. This allows the transition metal component contained in the glass to be oxidized when the glass is heat-treated while being molded into the desired shape or enhanced resistance to mechanical impacts. An optical glass having a high spectral transmittance can be obtained. In addition, the use of the optical glass produced by this invention is not limited to the use which requires temperature rising to reheating temperature.

  Moreover, it is preferable that the optical glass produced by this invention has high devitrification resistance. In particular, the optical glass produced according to the present invention preferably has a low liquidus temperature of 1200 ° C. or lower. More specifically, the upper limit of the liquidus temperature of the optical glass produced according to the present invention is preferably 1200 ° C, more preferably 1150 ° C, and most preferably 1100 ° C. This reduces the crystallization of the glass even when the temperature of the molten glass is lowered, so that the unnecessary evaporation of oxygen components from the molten glass and the elution of the components contained in the melting equipment are further suppressed, and the glass permeation is suppressed. The rate can be increased further. Moreover, since such glass is easy to vitrify, the clarification time in a clarification process can be shortened, and optical glass can be produced in a shorter time. On the other hand, the lower limit of the liquidus temperature of the optical glass produced according to the present invention is not particularly limited, but is generally approximately 500 ° C. or higher, specifically 550 ° C. or higher, and more specifically 600 ° C. or higher.

  Moreover, it is preferable that the optical glass produced by this invention has a low glass transition point (Tg). In particular, the optical glass produced according to the present invention preferably has a glass transition point (Tg) of 700 ° C. or lower. Thereby, since glass softens at lower temperature, glass can be press-molded at lower temperature. In addition, it is possible to extend the life of the mold by reducing oxidation of the mold used for press molding. Accordingly, the upper limit of the glass transition point (Tg) of the optical glass produced according to the present invention is preferably 700 ° C., more preferably 670 ° C., and most preferably 650 ° C. The lower limit of the glass transition point (Tg) of the optical glass produced according to the present invention is not particularly limited, but is generally 100 ° C. or higher, specifically 150 ° C. or higher, and more specifically 200 ° C. or higher. Many.

[Production of optical elements]
The optical glass produced according to the present invention can produce various optical elements and optical elements such as lenses and prisms useful for optical design. These optical elements are preferably used for optical devices such as cameras and projectors. As a result, the absorption of light by the optical element is reduced and the light transmittance is increased, so that high-definition and high-precision imaging characteristics and projection characteristics can be realized.

Table 1 shows the composition of the raw glass used for producing the optical glass, and the temperature and time of the melting step, the clarification step, the stirring step, the outflow step, and the molding step. In addition, the liquid phase temperature, refractive index (n _d ), Abbe number (ν _d ), glass transition point (Tg), and spectral transmittance for light having a wavelength of 420 nm before and after the reheating test are also produced. Table 1 shows. The following examples are merely for illustrative purposes and are not limited to these examples.

  In the examples (No. 1 to No. 4) and the comparative example (No. 1) of the present invention, oxides, hydroxides, carbonates, nitrates, fluorides, and water corresponding to the raw materials of the respective components. High-purity raw materials used for ordinary optical glasses such as oxides and metaphosphoric acid compounds were selected. After these were weighed so as to have the composition ratio of each Example and Comparative Example shown in Table 1, all raw materials were uniformly mixed, and melted at the melting temperature shown in Table 1 for 0.5 to 30 hours The cullet (raw glass) in which a part of the glass raw material was vitrified was cooled. Thereafter, the formed cullet was put into a tank made of platinum.

  Here, the liquidus temperature was calculated | required about the glass made from the same composition as raw material glass. The liquid phase temperature was measured by placing glass samples pulverized into granules with a diameter of about 2 mm on a platinum plate at intervals of 10 mm, holding them in a furnace with a temperature gradient of 800 ° C. to 1200 ° C. for 30 minutes, removing them, and cooling them. Later, the presence or absence of crystals in the glass sample was measured by observing with a microscope with a magnification of 80 times. Based on the value of the measured liquidus temperature, the melting temperature, fining temperature, stirring temperature, outflow temperature and molding temperature were determined as shown in Table 1.

  About the raw material glass put into the platinum tank, after melting the raw material glass at the melting temperature and melting time shown in Table 1, the temperature of the molten raw material glass is adjusted to the clarification temperature shown in Table 1, and the clarification shown in Table 1 is performed. The raw glass was clarified by standing for a period of time. Next, after adjusting the temperature of the molten glass to the stirring temperature shown in Table 1, using the stirring means provided along the bottom surface of the platinum tank, the stirring means was rotated along the bottom surface of the stirring tank. The molten glass was stirred for the stated stirring time. Thereafter, the temperature of the molten glass is adjusted to the outflow temperature shown in Table 1, the molten glass is caused to flow out from the outflow pipe provided on the bottom surface of the platinum tank, and the molten glass adjusted to the forming temperature shown in Table 1 is supplied to the mold. Then, these were gradually cooled to produce a glass.

Here, the refractive index of the glass obtained in Example (No.1~No.4) and Comparative Example (No.1) _{(n d)} and Abbe number ([nu _d), Japanese Optical Glass Industrial Standard JOGIS01 -Measured based on 2003. The glass used in this measurement was annealed under a slow cooling furnace with a slow cooling rate of −25 ° C./hr.

  Moreover, the glass transition point (Tg) of the glass obtained by an Example (No.1-No.4) and a comparative example (No.1) was calculated | required by measuring using a horizontal type | mold expansion measuring device. Here, the sample used for the measurement was φ4.5 mm and a length of 5 mm, and the heating rate was 4 ° C./min.

Moreover, about the transmittance | permeability of the glass obtained by an Example (No.1-No.4) and a comparative example (No.1), it measured according to Japan Optical Glass Industry Association standard JOGIS02. Specifically, the face-to-face parallel polished product having a thickness of 10 ± 0.1 mm was measured in accordance with JISZ8722 to measure the spectral transmittance with respect to light having a wavelength of 420 nm, and the presence / absence and degree of coloring of the glass were determined from the transmittance value. . In this example, the transmittance of the glass was measured before the reheating test assuming precision annealing and press molding and after the reheating test. Here, the glass reheating test was carried out by placing a prismatic glass sample of 15 mm × 15 mm × 30 mm prepared from the glass obtained in the examples and comparative examples on a refractory and placing it in an electric furnace for 150 minutes at room temperature. The temperature was raised to 20 ° C. higher than the glass transition point (Tg) of the glass sample, and the temperature was kept for 30 minutes. The glass after the reheating test was cooled to room temperature and taken out of the furnace, and then the two opposing surfaces were polished to a thickness of 10 mm ± 0.1 mm, and the spectral transmittance was measured by the same method as described above. .

  As shown in Table 1, each of the optical glasses obtained in Examples of the present invention has a spectral transmittance of 20% or more, more specifically, 40% for light having a wavelength of 420 nm before and after the reheating test. % Or more. On the other hand, the glass obtained in the comparative example has a spectral transmittance for light having a wavelength of 420 nm before the reheating test of lower than 20%, and a spectral transmittance for light having a wavelength of 420 nm before and after the reheating test is 40%. It was lower. For this reason, it is clear that the optical glass obtained by the example of the present invention has a higher spectral transmittance for visible light than the glass obtained by the comparative example before and after the reheating test, and is difficult to be colored. It was. In particular, in the optical glass obtained in the example of the present invention, the change in spectral transmittance with respect to light having a wavelength of 420 nm before and after the reheating test was suppressed to 20% or less, more specifically, 15% or less.

The optical glasses obtained in the examples of the present invention all have a refractive index (n _d ) of 1.80 or more, more specifically 1.84 or more, and this refractive index (n _d ) is 2. It was 20 or less, more specifically 2.00 or less, and was within the desired range.

The optical glasses obtained in the examples of the present invention all have an Abbe number (ν _d ) of 10 or more, more specifically 15 or more, and the Abbe number (ν _d ) of 29 or less, more specifically. Was 24 or less, and was within the desired range.

  In addition, the optical glasses of the examples of the present invention all have a liquidus temperature of 1200 ° C. or lower, more specifically less than 1100 ° C., and the liquidus temperature is 500 ° C. or higher, which is within a desired range. It was.

  Further, the optical glasses of the examples of the present invention all had a glass transition point (Tg) of 700 ° C. or less, more specifically 660 ° C. or less, and were within a desired range.

Therefore, the optical glass obtained in the examples of the present invention has a high dispersion (low Abbe number ν _d ) while having a refractive index (n _d ) within a desired range, and is less colored without heat treatment. It has been clarified that the coloring after the heat treatment is reduced, the devitrification resistance at the time of glass formation is high, and the press molding is easy to perform.

  Further, in the molding step of Example 2 of the present invention, the molten glass was molded into a predetermined shape, and when this molded body was heated to 650 ° C. for 12 hours and subjected to precision annealing, the spectral transmittance of the molded body after precision annealing was obtained. Was 45%.

  Although the present invention has been described in detail for the purpose of illustration, this embodiment is only for the purpose of illustration, and many modifications can be made by those skilled in the art without departing from the spirit and scope of the present invention. Will be understood.

Claims (20)

A method of producing an optical glass containing, as essential components, a P ₂ O ₅ component, and one or more selected from the group consisting of a Nb ₂ O ₅ component, a TiO ₂ component, and a WO ₃ component,
A step of melting the glass raw material (melting step), a step of clarifying the molten glass raw material (clarification step), a step of stirring the clarified molten glass (stirring step), a step of discharging the stirred molten glass (outflow step), And a step of forming the glass that has flowed out (forming step),
The method which performs the said stirring process at the temperature 0-200 degreeC higher than the liquidus temperature of a molten glass.   The method of Claim 1 which performs the said outflow process at the temperature 0-100 degreeC higher than the liquidus temperature of a molten glass.   The method according to claim 1 or 2, wherein the sum of the time during which the molten glass stays in the clarification step and the stirring step is 0.20 times or more and 10.00 times or less the time during which the molten glass stays in the melting step.   4. The method according to claim 1, wherein the temperature of the molten glass is adjusted not to be higher than the liquidus temperature by 250 ° C. or more through the melting step, the refining step, the stirring step, the outflow step, and the forming step. .   5. The method according to claim 1, wherein the temperature of the molten glass is adjusted to less than 1300 ° C. through the melting step, the clarification step, the stirring step, the outflow step, and the forming step. 10. One or more selected from the group consisting of 10.0 to 40.0% of P ₂ O ₅ component and Nb ₂ O ₅ component, TiO ₂ component, and WO ₃ component in mass% based on oxide. The method according to any one of claims 1 to 5, wherein an optical glass containing 0 to 70.0% is produced. % By mass on the oxide basis, _Nb 2 _{O 5} component and a method according to claim 6, wherein for producing an optical glass containing at least one of the foregoing 30.0% selected from the group consisting of TiO ₂ component. % By mass based on oxide,
Sb ₂ O ₃ component 0-1.0% and / or SnO ₂ component 0-0.5%
The method in any one of Claim 1 to 7 which manufactures the optical glass containing each component of these. The method according to claim 8, wherein an optical glass having an oxide-based mass sum Sb ₂ O ₃ + SnO ₂ of more than 0% and 1.0% or less is produced. % By mass based on oxide,
Li ₂ O component 0-20.0% and / or Na ₂ O component 0-35.0% and / or K ₂ O component 0-20.0%
The method in any one of Claim 1 to 9 which manufactures the optical glass containing each component of these. An optical glass in which the mass sum of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) is 35.0% or less in terms of mass% based on the oxide is produced. The method of claim 10. % By mass based on oxide,
MgO component 0-5.0% and / or CaO component 0-10.0% and / or SrO component 0-10.0% and / or BaO component 0-30.0%
The method of any one of Claim 1 to 11 which manufactures the optical glass containing each component of these.   An optical glass in which the mass sum of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is 30.0% or less based on the oxide-based mass%. The method of claim 12. % By mass based on oxide,
Y ₂ O ₃ component 0 to 10.0% and / or La ₂ O ₃ component 0 to 10.0% and / or Gd ₂ O ₃ component 0 to 10.0%
The method of any one of Claims 1-13 which manufactures the optical glass containing each component of these. An optical glass having a mass sum of 20.0% or less of Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of Y, La, and Gd) in terms of mass% based on oxide is produced. The method of claim 14. % By mass based on oxide,
SiO ₂ component 0 to 10.0% and / or B ₂ O ₃ component 0 to 10.0% and / or GeO ₂ component 0 to 10.0% and / or Bi ₂ O ₃ component 0 to 20.0% and / Or ZrO ₂ component 0 to 10.0% and / or ZnO component 0 to 10.0% and / or Al ₂ O ₃ component 0 to 10.0% and / or Ta ₂ O ₅ component 0 to 10.0%
The method of any one of Claims 1-15 which manufactures the optical glass containing each component of these.   The method according to any one of claims 1 to 16, wherein an optical glass having a refractive index (nd) of 1.70 or more and 2.20 or less and an Abbe number (νd) of 10 or more and 29 or less is produced.   The method according to claim 1, wherein an optical glass having an Abbe number (νd) of less than 19 is produced.   Optical glass having a spectral transmittance of 20% or more for light having a wavelength of 420 nm before and after a reheating test in which the glass subjected to the forming step is heated to a reheating temperature of (Tg-100) ° C. or higher and (Tg + 100) ° C. or lower. A method according to any one of claims 1 to 18 wherein   An optical apparatus using the optical glass produced by the method according to claim 1.