JP2011136884A - Method for producing optical glass and optical equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing optical glass by which optical glass hardly discolored while having a low Abbe's number is obtained. <P>SOLUTION: The optical glass contains, as essential components, a P<SB>2</SB>O<SB>5</SB>component and at least one selected from the group comprising a Nb<SB>2</SB>O<SB>5</SB>component, a TiO<SB>2</SB>component, and a WO<SB>3</SB>component. The method for producing the optical glass includes a cullet production process for producing glass cullets by melting a glass raw material and then rapidly cooling the molten glass raw material. In the cullet production process, the temperature in a melting furnace is set within a temperature range higher by 0 to 200°C than the temperature of a formed liquid phase of glass. <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 glass raw material containing P ₂ O ₅ is used, this glass raw material is vitrified at about 1000 ° C. to 1200 ° C. with a quartz crucible or a platinum crucible, and the obtained crude glass (cullet) is melted with a platinum crucible. A method is known in which a temperature is lowered after defoaming and clarification, and a step of pouring this out from an outflow pipe and casting it into a mold (see Patent Document 1).

In addition, a process of transferring the glass raw material containing P ₂ O ₅ to a quartz crucible or a platinum crucible, homogenizing the glass raw material melted at 1000 to 1300 ° C., then flowing it out of the crucible, casting it into a mold, and gradually cooling it. The method of having is known (refer patent document 2).

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

  However, when an optical glass is produced using the methods described in Patent Document 1 and Patent Document 2, the obtained glass is colored and has low light transmittance or devitrification, so that a particularly short wavelength of visible light is used. It cannot be used for applications that transmit side light.

  In particular, in the method described in Patent Document 2, it is indispensable that the temperature is again raised to a temperature equal to or higher than the temperature (glass transition temperature −100 ° C.) after cooling. However, even after heat-treated glass formed by the method described in Patent Document 2, the light transmittance is not sufficiently high, so that it is used for applications that transmit visible light, particularly on the short wavelength side. I can't.

The present invention has been made in view of the above circumstances, and in a glass containing a P ₂ O ₅ component, a method for producing an optical glass capable of obtaining a glass having high transmittance for visible light and little coloring. The purpose is to provide.

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 on the raw glass. And a glass having high dispersion by performing a cullet preparation step in which the raw glass is melted at a temperature 0 to 200 ° C. higher than the liquidus temperature of the glass to be formed. It has been found that a cullet having a high transmittance for visible light of glass can be obtained, and the present invention has been completed. 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. ,
Including a cullet preparation process in which the glass raw material is rapidly cooled after melting to create a cullet,
A method of maintaining the temperature in the melting furnace in the cullet production step in a temperature range 0 to 200 ° C. higher than the liquidus temperature of the glass to be produced.

  (2) The method according to (1), wherein a raw material containing at least one selected from the group consisting of orthophosphoric acid and a complex salt thereof is used as the glass raw material.

  (3) When melting the glass raw material, one or more selected from the group consisting of orthophosphoric acid and its complex salt and other raw materials are mixed and supplied to the melting furnace (2) Method.

  (4) One or more selected from the group consisting of orthophosphoric acid and a complex salt thereof and other raw materials are mixed to form a granular material, and then the granular material is set to 0 below the liquidus temperature. The method according to (2) or (3), wherein the method is divided and supplied to a melting furnace maintained at a temperature range of ~ 200 ° C.

  (5) The method according to (4), wherein, when the granular material is divided and supplied to the melting furnace, a new granular material is supplied after foaming of the already dissolved granular material is substantially completed.

  (6) The method according to any one of (1) to (5), wherein the oxygen concentration in the melting furnace during the melting is maintained at 5% or more.

  (7) The method according to any one of (1) to (6), wherein the temperature in the melting furnace during the melting is adjusted to less than 1300 ° C.

(8) 10.0% by mass of oxide basis, 10.0 to 40.0% of P ₂ O ₅ , and 10.0 or more selected from the group consisting of Nb ₂ O ₃ , TiO ₂ and WO ₃ The method according to any one of (1) to (7), wherein an optical glass containing ˜70.0% is produced.

(9) The method according to (8), 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%.

(10)% by mass based on oxide,
Sb ₂ O ₃ component 0 to less than 0.5% and / or SnO ₂ component 0 to 1.0%
The method according to any one of (1) to (9), wherein an optical glass containing each of the components is produced.

(11) The method according to (10), wherein an optical glass having an oxide-based mass sum Sb ₂ O ₃ + SnO ₂ of 1.5% or less is produced.

(12)% 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%
(1) The method in any one of (11) which manufactures the optical glass containing each component of.

(13) The method according to (12), wherein an optical glass having an oxide-based mass sum Li ₂ O + Na ₂ O + K ₂ O of 35.0% or less is produced.

(14)% 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 according to any one of (1) to (13), wherein an optical glass containing each of the components is produced.

  (15) The method according to (14), wherein an optical glass having an oxide-based mass sum MgO + CaO + SrO + BaO of 30.0% or less is produced.

(16)% 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 according to any one of (1) to (15), wherein an optical glass containing each of the components is produced.

(17) The method according to (16), wherein an optical glass having an oxide-based mass sum Y ₂ O ₃ + La ₂ O ₃ + Gd ₂ O ₃ of 20.0% or less is produced.

(18)% 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%
(1) The method in any one of (17) which manufactures the optical glass containing each component of.

  (19) 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 25 or less is described in any one of (1) to (18) Method.

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

(21) The wavelength at which the spectral transmittance is 70% before and after the reheating test in which the glass subjected to the forming step is heated to a reheating temperature of (Tg−200) ° C. or more and (Tg + 100) ° C. or less (λ ₇₀ The method according to any one of (1) to (20), wherein an optical glass having a difference of 500 nm or less is produced.

  (22) An optical instrument using optical glass manufactured by the method according to any one of (1) to (21).

According to the present invention, the raw glass is obtained after containing a P ₂ O ₅ component and at least one selected from the group consisting of Nb ₂ O ₅ component, TiO ₂ component and WO ₃ component. It is possible to produce a highly dispersed glass by performing a cullet production process in which the raw glass is melted at a temperature 0 to 200 ° C. higher than the liquidus temperature of the glass, and the glass is transparent to visible light. A cullet with a high rate is obtained. Therefore, it is possible to provide an optical glass manufacturing method capable of obtaining a glass having a desired optical property, particularly a low Abbe number, and having a high transmittance for visible light and little coloring.

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 cullet preparation step of rapidly cooling the glass raw material after melting to create a cullet, and the cullet preparation step is performed at a temperature higher by 0 to 200 ° C. than the liquidus temperature of the glass. Accordingly, the visible light of the cullet formed by the cullet manufacturing process at a predetermined temperature while the refractive index and dispersion are increased by one or more selected from the Nb ₂ O ₅ component, the TiO ₂ component, and the WO ₃ component. The transmittance for is increased. Therefore, it is possible to obtain a glass having desired optical characteristics and capable of reducing coloring.

  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 in mass% with respect to the total mass of the glass raw material having an oxide equivalent composition. Here, the “oxide equivalent composition” means that the oxide, composite salt, metal fluoride, etc. used as a glass raw material in the present invention are all decomposed and / or melted to be converted into oxides. In addition, the total mass of the generated oxide is 100% by mass, and each component contained in the glass raw material is described.

<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 in the visible region of the glass. 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 is one or more selected from the group consisting of orthophosphoric acid and complex salts thereof, such as Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , It can be contained in the glass raw material with H ₃ PO ₄ or the like, is preferably contained in the glass raw material by using orthophosphoric acid _(H 3 PO _4). This reduces the refractive index of the glass and the increase of the liquidus temperature because the alkali metal component, alkaline earth metal component, etc. contained together when the P ₂ O ₅ component is contained in the raw glass are reduced. Thus, an optical glass having desired optical characteristics and light transmittance can be obtained. Further, since the respective components contained together when containing P ₂ O ₅ component in the raw material glass is reduced, because the flexibility of the composition of the raw material glass is enhanced to obtain a more Abbe number of low optical glass be able to.

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 15.0%, and most preferably less than 10.0%. 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 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, and most preferably. May be 14.0% 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, the desired high refractive index and high dispersion can be obtained, but it is difficult to reduce the Nb ₂ by simply adding the Sb ₂ O ₃ component and / or the SnO ₂ component described below. Coloring of the glass due to the reduction of the O ₅ component and / or the TiO ₂ component is reduced. Therefore, it is possible to obtain an optical glass having desired optical characteristics and capable of reducing coloring. 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 and melted. In particular, by making the content of the Sb ₂ O ₃ component 1.0% or less, dissolution in the cullet of the melting equipment (particularly noble metals such as Pt) by oxygen released from the Sb ₂ O ₃ component is reduced. Therefore, coloring of glass can be reduced. 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. Less than 0.4%, most preferably less than 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, when the content of the SnO ₂ component is 1.0% or less, the devitrification resistance of the glass can be hardly lowered. 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 1.0%, more preferably 0.5%, still more preferably 0.25%, most preferably 0.1. % Is the upper limit. 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. This reduces the reduction of glass components, particularly Nb ₂ O ₅ components, TiO ₂ components and WO ₃ components, when melting and melting the glass. Therefore, it is possible to increase the transmittance for visible light of glass, which tends to be reduced by reduction of Nb ₂ O ₅ component, TiO ₂ component and WO ₃ component, thereby reducing the coloration of cullet. Coloring of the glass can be reduced. In particular, when one or more selected from the group consisting of Sb ₂ O ₃ component and SnO ₂ component is contained, the group consisting of Sb ₂ O ₃ component and SnO ₂ component with respect to the total mass of the glass raw material of the oxide equivalent composition The mass sum of one or more selected more preferably exceeds 0%, more preferably 0.005%, and most preferably 0.010%. On the other hand, oxygen released from the Sb ₂ O ₃ component and the SnO ₂ component by reducing the mass sum of at least one selected from the group consisting of the Sb ₂ O ₃ component and the SnO ₂ component to 1.5% or less. Since the dissolution of the melting equipment (particularly noble metals such as Pt) into the cullet due to is reduced, the coloring 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 the oxide equivalent composition is preferably 1.5%, more preferably 1. The upper limit is 0%, most preferably 0.5%.

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%. Although Li 2 _O component is possible to obtain an optical glass having a desired high dispersion and high transmittance even without containing the Li 2 _O component that contains more than 0%, the glass transition point ( Since Tg) becomes low, it is possible to obtain a glass that has a high dispersion and is easily softened at a low temperature. Accordingly, in this case, 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 more than 0%, more preferably more than 0.3%, and most preferably 0.5%. % Is the lower limit. 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 2.0. % 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 15.0%. 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 at the time of melting and melting the glass, and is an optional component in the glass raw material. In particular, by setting the content ratio of the Al ₂ O ₃ component to 10.0% or less, it is possible to weaken the devitrification tendency of the glass while improving the solubility and 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.

[Caret production process]
The cullet manufacturing step is a step of forming a cullet after melting a batch formed by mixing at least a part of the glass raw material supplied to the melting furnace. By forming a cullet with less blackening due to reduction of transition metal components such as Ti, Nb, and W in the cullet production process, the reduction of the transition metal component until the glass is produced by melting the cullet is included in the glass. It is reduced to such an extent that it can be eliminated by oxygen released from components such as Sb ₂ O ₃ component and / or SnO ₂ component. At the same time, by forming a cullet with less elution of components from the melting equipment in the cullet production process, it becomes easy to reduce the coloring of the glass obtained from the cullet. Therefore, it is possible to easily obtain an optical glass having a high visible light transmittance. Moreover, since the vitrification of the glass raw material is divided into a plurality of times, the vitrification of the glass raw material becomes easier to proceed, so that an optical glass with high devitrification resistance can be obtained.

  Among the glass raw materials described above, one or more selected from the group consisting of orthophosphoric acid and its complex salt is mixed with other raw materials to form a granular material, and the mixed glass raw materials are supplied to the melting furnace. Is preferred. As a result, the atmosphere in which the glass raw material was wet by the liquid normal phosphoric acid and its composite salt and was adjacent to the glass raw material until the reaction of the normal phosphoric acid and the composite salt started at the latest. Is estimated to be discharged. Therefore, it is possible to reduce the amount of gas generated when orthophosphoric acid or complex salt is dehydrated by heating, or when normal phosphoric acid or complex salt dehydrated by heating reacts with other raw materials, and the raw material for cullet production It is estimated that the heat transfer in the glass can be increased. Accordingly, since the unmelted residue at the time of cullet production can be reduced, a uniform optical glass having a desired high dispersion can be obtained. Here, as the orthophosphoric acid and the complex salt thereof, a heated liquid form may be used, or a cooled powder form may be used. In particular, by using the former, it is presumed that the atmosphere adjacent to the glass raw material before the raw material glass is heated is discharged, so that the raw material glass can be heated more uniformly. On the other hand, the use of the latter makes it difficult for other materials to be wetted by normal phosphoric acid and its composite salt during mixing, so that it is possible to easily mix the normal phosphoric acid or composite salt with other materials. The “molten glass” in the present specification includes a molten glass raw material before vitrification in addition to a molten glass raw material after vitrification.

  At this time, it is particularly preferable that the granular material formed by mixing orthophosphoric acid or a composite salt and other raw materials is divided and supplied to a melting furnace maintained at a cullet forming temperature described later. In particular, by supplying powder particles divided at different timings, the gas generated by heating the powder particles is divided and discharged from the raw glass multiple times. The amount can be reduced. That is, the raw glass can be heated more evenly, and unmelted raw material glass can be reduced. On the other hand, by dividing and supplying the granular material from different positions in the melting furnace, the gas generated by heating the granular material is divided and discharged from the raw glass into a plurality of locations. Generation of gas can be reduced. That is, the raw glass can be heated more evenly, and unmelted raw material glass can be reduced. In addition, by supplying powder particles separately from different timings and / or different positions in the melting furnace, local temperature drop due to the powder particles can be suppressed, so the heating temperature of the powder particles is culled. The temperature can be easily maintained, and devitrification due to crystallization of the glass component can be reduced.

  When the granular material is divided into different timings and supplied to the melting furnace, it is preferable to supply a new granular material after foaming of the already dissolved granular material is substantially completed. As a result, foaming from the already dissolved powder and foaming from the new powder do not occur at the same time, so the amount of gas generated from the raw glass per unit time can be further reduced, and the raw glass remains undissolved. Can be further reduced. Here, the time from the supply of the granular material to the almost complete foaming of the granular material is preferably 30 minutes, more preferably from the viewpoint of reducing the amount of gas generated per unit time from the raw glass. The lower limit is 40 minutes, most preferably 60 minutes. On the other hand, the time from the supply of the granular material to the completion of the foaming of the granular material is preferably 5 hours, more preferably from the viewpoint of reducing the dissolution of the components contained in the melting furnace into the molten glass. Is 4 hours, most preferably 3 hours.

The cullet preparation temperature for melting the raw glass in the cullet preparation step is (liquid phase temperature + 200 ° C.) or less in relation to the liquid phase temperature of the obtained glass. The cullet preparation temperature is more preferably (liquid phase temperature + 180 ° C.) or less, and most preferably (liquid phase temperature + 160 ° C.) or less. Thereby, excessive evaporation of the gaseous component from the melt | dissolved raw material glass, especially an oxygen component is reduced. Therefore, the transition metal component contained in the formed cullet, in particular the Nb ₂ O ₅ component, the TiO ₂ component and / or the WO ₃ component capable of providing high dispersion, the cullet coloring is reduced in the glass. It is reduced to such an extent that it can be eliminated by oxygen released from components such as ₂ O ₃ component and / or SnO ₂ component. That is, it is possible to obtain an optical glass capable of increasing the transmittance for visible light while having a desired high dispersion. The cullet production temperature is preferably less than 1250 ° C, more preferably less than 1200 ° C, and most preferably less than 1180 ° C. Thereby, since the elution to the molten glass of the component contained in a melting furnace is reduced, coloring of the cullet by these components can be reduced, and lifetime improvement of a melting furnace can be aimed at.

  On the other hand, the cullet production temperature is set to be equal to or higher than the liquid phase temperature of the obtained glass, more preferably (liquid phase temperature + 10 ° C.), and most preferably (liquid phase temperature + 20 ° C.). Thereby, crystallization of the melted glass component is reduced, and devitrification hardly occurs in the obtained cullet, so that an optical glass having high stability can be obtained. Further, the cullet production temperature of the molten glass in the cullet production process is preferably 1020 ° C. or higher, more preferably 1050 ° C. or higher, and most preferably 1080 ° C. or higher. This makes it difficult for the raw glass to melt, particularly the high-dispersion component, so that a homogeneous optical glass having a desired high dispersion can be obtained.

  Here, the liquidus temperature of the obtained glass is formed from a glass having the same composition as the raw glass, and a glass sample pulverized into particles having a diameter of about 2 mm is placed on a platinum plate and has a temperature gradient of 800 ° C. to 1220 ° C. The glass is held for 30 minutes in a connected furnace, taken out, and after cooling, is measured by observing the presence or absence of crystals in the glass with a microscope with a magnification of 80 times. Required from low temperature.

  In addition, it is preferable to use the average temperature of the molten glass which retains in a melting furnace in a cullet preparation process as "cullet preparation 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 melting furnace and the temperature of the molten glass in the lower part of the melting furnace. This makes it easy to suppress blackening of the molten glass and crystallization of the glass component even when a temperature gradient is generated inside the molten glass, so that an optical glass having a high visible light transmittance can be obtained. Can be made easier. Here, the temperature of the molten glass in the upper part and the lower part of the melting furnace can be determined using, for example, a thermocouple provided in the melting furnace or on the wall surface. Moreover, the temperature of the molten glass in the upper part of a melting furnace can also be calculated | required using a radiation thermometer.

  The time for holding the molten glass obtained by melting the raw glass is appropriately selected depending on the shape and capacity of the melting furnace. More specifically, the time for holding the molten glass after the raw glass is supplied is preferably 0.5 hours or more, more preferably 2 hours or more, and most preferably 5 hours or more. This makes it difficult for the raw glass to melt, particularly the high-dispersion component, so that a homogeneous optical glass having a desired high dispersion can be obtained. On the other hand, the time for holding the molten glass is preferably 24 hours or less, more preferably 12 hours or less, and most preferably 8 hours or less. Thereby, the contact time between the molten glass and the melting furnace is shortened, and the elution of the components contained in the melting furnace into the molten glass is reduced, so that the coloring of the glass by these components can be reduced.

In the specification of the present application, the above-mentioned time for holding the molten glass refers to an average time during which the molten glass stays in the melting furnace within the range of the cullet production temperature. For example, when the supply and discharge rates of the raw material glass are constant, when the supply of the glass raw material to the melting furnace is started (if the raw glass is heated to the cullet preparation temperature after the supply of the raw glass, Δt _ab is the time from when the temperature reaches the above-mentioned cullet production temperature) to when the glass raw material starts to be discharged from the melting furnace (or when the melting furnace temperature is cooled below the above-mentioned cullet production temperature). The glass from the time when the supply of the glass raw material to the melting furnace is completed (when the raw glass is heated to the cullet preparation temperature after the supply of the raw glass, the temperature of the supplied glass raw material reaches the above cullet preparation temperature). Δt _cd is the time until the end of discharging the raw material from the melting furnace (or the time when the melting furnace temperature is cooled to the cullet production temperature or lower). At this time, the melting time Δt ₁ is obtained from the following equation (1).

  It is preferable to keep the oxygen concentration in the melting furnace at 5% or more while melting and holding the raw glass in the cullet production process. This is because the atmosphere adjustment in the cullet production process for producing the cullet from the batch greatly affects the oxidation and reduction of the transition metal. By maintaining the oxygen concentration in the melting furnace at 5% or more and forming a state in which the reducing atmosphere is weak in the melting furnace, reduction of transition metal components that cause high dispersion of Ti, Nb, W, etc. contained in the cullet is reduced. Reduced. Therefore, it is possible to obtain an optical glass that has low absorption in the vicinity of 400 to 450 nm and 600 to 700 nm and can increase the transparency to visible light. Here, the oxygen concentration in the melting furnace is preferably 5% or more, more preferably 10% or more, and most preferably 15% or more. In the present specification, “oxygen concentration” refers to an average oxygen concentration in the melting furnace. On the other hand, the oxygen concentration in the melting furnace is preferably maintained at 30% or less. Thereby, since excessive dissolution of oxygen into the molten glass is reduced, a cullet with less elution of components from the melting equipment can be formed. Here, the upper limit of the oxygen concentration in the melting furnace is preferably 30%, more preferably 25%, and most preferably 20%.

  After holding the molten glass for a predetermined time, the molten glass is cooled to room temperature to form a cullet. As a result, a transition metal component that causes high dispersion such as Ti, Nb, and W is contained, but a cullet with less elution of the component from the melting equipment and less coloring can be obtained. An optical glass with high transmittance can be easily manufactured.

[Production of optical glass]
In the production method of the present invention, the optical glass is produced by supplying the cullet produced in the above-described cullet production process to the melting tank. The optical glass production procedure is not particularly limited. For example, a melting process for forming molten glass from cullet, a clarification process for retaining molten glass raw material for a predetermined period of time, and agitation of the clarified molten glass to remove bubbles. An optical glass is produced by performing an agitation process, an outflow process for causing the stirred molten glass to flow out of the agitation tank, and a molding process for molding the molten glass supplied at a predetermined flow rate.

  In the production method of the present invention, it is preferable to adjust the temperature of the molten glass to less than 1300 ° C. through the melting step, the clarification step, the stirring step, the outflow step, and the molding step, so as not to be higher than 250 ° C. above the liquidus temperature. It is preferable to adjust. Thereby, excessive evaporation of oxygen from the molten glass is reduced, reduction of the transition metal component is reduced, and elution of components contained in the melting tank is reduced. Therefore, it is possible to obtain an optical glass that takes advantage of the characteristics of cullet having a high visible light transmittance. Here, 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.).

  Moreover, in the manufacturing method of this invention, it is preferable that the time which a melt | dissolution process, a clarification process, a stirring process, and an outflow process require is short within the range with which the effect by each process is acquired. More specifically, the total time required for the melting step, the clarification step, the stirring step, and the outflow step is preferably 24 hours or less, more preferably 20 hours or less, and most preferably 15 hours or less. Thereby, excessive evaporation of oxygen from the molten glass is reduced, reduction of the transition metal component is reduced, and elution of components contained in the melting tank is reduced. Therefore, it is possible to obtain an optical glass that takes advantage of the characteristics of cullet having a high visible light transmittance. On the other hand, the lower limit of the total time of these steps is not particularly limited and is appropriately determined according to the technical level, but is generally approximately 3 hours or more.

[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 (n _d ) of the optical glass is preferably 1.70, more preferably 1.75, and most preferably 1.80, preferably 2.20, more preferably 2.15, The upper limit is preferably 2.10. Further, the upper limit of the Abbe number (ν _d ) of the optical glass is preferably 25, 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 coloring of the glass that occurs when forming a highly dispersed glass is reduced. In particular, when the Sb ₂ O ₃ component and / or SnO ₂ component is used for the raw glass, even the coloring of the glass, which is difficult to reduce simply by adding the Sb ₂ O ₃ component and / or SnO ₂ component, is also possible. Reduced. Therefore, an optical glass capable of reducing coloring while having a desired high dispersion can be obtained. 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 has a spectral transmittance of 70% with a 10 mm thick sample after a reheating test in which the temperature is raised to a reheating temperature of (Tg−200) ° C. or more and (Tg + 100) ° C. or less. The wavelength (λ ₇₀ ) shown is 500 nm or less, more preferably 480 nm or less, and most preferably 450 nm or less. By reheating the glass, the glass is dedistorted while the dissolution of impurities in the glass is suppressed. In particular, when an Sb ₂ O ₃ component and / or SnO ₂ component is used for the raw glass, the transition metal component contained in the reduced state in the glass is oxidized by the Sb ₂ O ₃ component and / or the SnO ₂ component. As a result, coloring is reduced. From the above, the absorption edge of the obtained glass can be positioned in the vicinity of the ultraviolet region, and the transparency of the glass in the visible region can be enhanced. Therefore, this optical glass can be used as a material for optical elements such as lenses.

Moreover, it is more preferable that the optical glass produced according to the present invention has little color change when reheated. In particular, the optical glass produced according to the present invention has a wavelength (λ) in which the spectral transmittance is 70% before and after the reheating test in which the temperature is raised to a reheating temperature of (Tg−200) ° C. or more and (Tg + 100) ° C. or less. ₇₀ ) is 500 nm or less, more preferably less than 300 nm, still more preferably less than 200 nm, and most preferably less than 100 nm. Since such glass has already increased light transmittance before the reheating test, the time required for the reheating process for reheating the glass is shortened, or the reheating process is substantially included. Without it, the transparency of the glass in the visible range can be increased. In addition, since the optical glass produced by this invention should just have desired transparency at least after reheating, the wavelength ((lambda) ₇₀ ) which shows the spectral transmittance 70% of the optical glass before reheating is measured. You don't have to.

  Here, the optical glass produced according to the present invention may be subjected to, for example, precision annealing and press molding at the same time when the temperature is raised to the above-described reheating temperature. As a result, the glass is reheated while being molded into a desired shape or enhanced resistance to mechanical impact, so that it has a high spectral transmittance while having the desired shape and mechanical properties. An optical glass having the same 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 melted raw glass is lowered, so that the evaporation of oxygen components more than necessary in the cullet production process and the elution of the components contained in the melting equipment are further suppressed. The transmittance can be further increased. Moreover, since such glass is easily vitrified, the time required for the cullet production process can be shortened, and a high-quality cullet 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 the production of the optical glass, the temperature and oxygen concentration in the melting furnace in the cullet production process, and the time for holding the molten glass in the melting furnace. Moreover, the liquid phase temperature, refractive index (n _d ), Abbe number (ν _d ), glass transition point (Tg), and wavelength at which the spectral transmittance before and after the reheating test is 70% of the optical glass to be produced. (Λ ₇₀ ) is also shown in Table 1. The following examples are merely for illustrative purposes and are not limited to these examples.

In Examples (No. 1 to No. 4) and Reference Examples (No. 1 to No. 2) of the present invention, oxides, hydroxides, carbonates, nitrates, and the like corresponding to the raw materials for each component, respectively. High-purity raw materials used for ordinary optical glass such as fluorides, hydroxides, and metaphosphoric acid compounds were selected. Among these, orthophosphoric acid was selected as a raw material for the P ₂ O ₅ component. These were weighed so as to have the composition ratio of each Example and Reference Example shown in Table 1, and after mixing raw materials other than normal phosphoric acid uniformly, liquid normal phosphoric acid was added and mixed uniformly. Thus, a granular material was produced.

  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 temperature in the melting furnace in the cullet production process was determined as shown in Table 1.

  The granular material which consists of glass raw materials was divided | segmented and supplied to the melting furnace hold | maintained at the cullet formation temperature of Table 1, 1 to 50 times, and the granular material was dissolved. The supply of the powder particles was performed every 0.5 to 3 hours so that the new powder particles were supplied after foaming of the already dissolved powder particles was substantially completed. After holding the molten glass for 0.5 to 5 hours after all of the powder particles were supplied, the molten glass was cooled to room temperature to form cullet.

  The formed cullet is put into a platinum crucible, melted in a temperature range of 1000 to 1300 ° C. for 2 to 10 hours in accordance with the melting difficulty of the glass composition, homogenized with stirring and blown out of bubbles, etc. The temperature was lowered to 1250 ° C. or lower, and the mixture was homogenized with stirring, cast into a mold, and slowly cooled to produce glass.

Here, as for the refractive index (n _d ) and Abbe number (ν _d ) of the glass obtained in Examples (No. 1 to No. 4) and Reference Examples (No. 1 to No. 2), Nippon Optical Glass Measurement was performed based on the industry association standard JOGIS01-2003. 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 reference example (No.1-No.2) is by measuring using a horizontal type | mold expansion measuring device. Asked. 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 reference example (No.1-No.2), it measured according to Japan Optical Glass Industry Association standard JOGIS02. Specifically, a facing parallel polished product having a thickness of 10 ± 0.1 mm is measured according to JISZ8722 to measure a spectral transmittance of 200 to 800 nm to obtain λ ₇₀ (wavelength at a transmittance of 70%), and coloring of the glass We asked for the presence and degree. 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 reference examples on a refractory and placing it in an electric furnace in 150 minutes at room temperature. The temperature was raised to −200 to + 100 ° 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, then the two opposing surfaces were polished to a thickness of 10 mm ± 0.1 mm, and λ ₇₀ was measured by the same method as described above.

As shown in Table 1, all of the optical glasses obtained in the examples of the present invention have a λ ₇₀ (wavelength at 70% transmittance) after reheating test of 500 nm or less, more specifically 450 nm or less. there were. On the other hand, in the glass obtained in Reference Example 1, λ ₇₀ after the reheating test was larger than 450 nm. For this reason, it became clear that the optical glass obtained by the Example of this invention is hard to be colored compared with the glass obtained in Reference Example 1. In particular, the λ ₇₀ of the optical glass obtained in Example 1 of the present invention was suppressed to 50 nm or less, more specifically 10 nm or less, before and after the reheating test.

The optical glasses obtained in the examples of the present invention all have a refractive index (n _d ) of 1.70 or more, more specifically 1.80 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 16 or more, and the Abbe number (ν _d ) of 25 or less. Was 24.5 or less, which was within the desired range.

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

  The optical glasses of the examples of the present invention all had a glass transition point (Tg) of 700 ° C. or lower, more specifically 680 ° C. or lower, and were within a desired range.

Therefore, the optical glass obtained in the example of the present invention has a high dispersion (low Abbe number ν _d ) while the refractive index (n _d ) is within a desired range, and particularly in the visible region after reheating. It became clear that the transparency with respect to the light of a wavelength was high, the devitrification resistance at the time of glass formation was high, and it was easy to press-mold.

Moreover, when the glass produced using the cullet of Example 2 of the present invention was molded into a predetermined shape and this molded body was heated to 630 ° C. for 48 hours and precision annealed, λ of the molded body after precision annealing was obtained. ₇₀ was 441 nm.

  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 (22)

A method for producing an optical glass containing, as an essential component, one or more selected from the group consisting of a P ₂ O ₅ component, a Nb ₂ O ₅ component, a TiO ₂ component, and a WO ₃ component,
Including a cullet preparation process in which the glass raw material is rapidly cooled after melting to create a cullet,
A method of maintaining the temperature in the melting furnace in the cullet production step in a temperature range 0 to 200 ° C. higher than the liquidus temperature of the glass to be produced.   The method according to claim 1, wherein a raw material containing at least one selected from the group consisting of orthophosphoric acid and a complex salt thereof is used as the glass raw material.   The method according to claim 2, wherein when the glass raw material is melted, one or more selected from the group consisting of orthophosphoric acid and a complex salt thereof and another raw material are mixed and supplied to the melting furnace.   One or more selected from the group consisting of orthophosphoric acid and its complex salt and other raw materials are mixed to form a powder, and then the powder is 0 to 200 ° C. above the liquidus temperature. The said method of any one of Claim 2 to 3 divided | segmented and supplied to the melting furnace hold | maintained at the high temperature range.   5. The method according to claim 4, wherein when the granular material is divided and supplied to the melting furnace, a new granular material is supplied after foaming of the already dissolved granular material is substantially completed.   The method according to any one of claims 1 to 5, wherein the oxygen concentration in the melting furnace during the melting is maintained at 5% or more.   The method in any one of Claim 1 to 6 which adjusts the temperature in the said melting furnace in the said melting | dissolving to less than 1300 degreeC. One or more selected from the group consisting of 10.0 to 40.0% of P ₂ O ₅ and Nb ₂ O ₃ , TiO _2, and WO ₃ in terms of mass% based on oxides, 10.0 to 70. The method according to any one of claims 1 to 7, wherein an optical glass containing 0% is produced. % By mass on the oxide basis, _Nb 2 _{O 5} component and a method according to claim 8, 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 to less than 0.5% and / or SnO ₂ component 0 to 1.5%
The method in any one of Claim 1 to 9 which manufactures the optical glass containing each component of these. The method of claim 10, wherein the mass sum _{Sb 2 O} 3 + SnO 2 on the oxide basis is for producing an optical glass is 1.5% or less. % 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 of any one of Claim 1 to 11 which manufactures the optical glass containing each component of these. The method of claim 12, wherein the mass sum _{Li 2 O + Na 2 O +} K 2 O based on oxides to produce an optical glass is not more than 35.0%. % 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 Claims 1-13 which manufactures the optical glass containing each component of these.   The method of Claim 14 which manufactures the optical glass whose mass sum based on an oxide MgO + CaO + SrO + BaO is 30.0% or less. % 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 1-15 which manufactures the optical glass containing each component of these. 17. The method of claim 16, wherein the mass sum of oxide basis _{Y 2 O 3 + La 2 O} 3 + Gd 2 O 3 to produce a optical glass is not more than 20.0%. % 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 in any one of Claim 1 to 17 which manufactures the optical glass containing each component of these.   The method according to any one of claims 1 to 18, 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 25 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. Difference in wavelength (λ ₇₀ ) at which the spectral transmittance shows 70% before and after the reheating test in which the glass subjected to the forming step is heated to a reheating temperature of (Tg−200) ° C. or more and (Tg + 100) ° C. or less. The method according to any one of claims 1 to 20, wherein an optical glass having a thickness of 500 nm or less is produced.   An optical apparatus using the optical glass produced by the method according to claim 1.