JP2009242207A - Optical glass, optical element and optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain optical glass having high thermal stability regardless of having a refractive index (n<SB>d</SB>) and an Abbe's number (&nu;<SB>d</SB>) within their predetermined ranges and to provide a preform for precision press molding and an optical element using it. <P>SOLUTION: The optical glass contains, in mass%, an SiO<SB>2</SB>ingredient of 6.0-40.0%, a B<SB>2</SB>O<SB>3</SB>ingredient of 7.0-42.0%, an La<SB>2</SB>O<SB>3</SB>ingredient of 1.0-56.0%, a TiO<SB>2</SB>ingredient of 0.1-20.0% to the total mass of a glass composition in terms of an oxide. The optical element is produced by precisely press-molding the optical glass. In the optical glass, the thermal stability of the glass is enhanced because the difference between a glass transition point (Tg) and a crystallization starting temperature (Tx) becomes large by containing the SiO<SB>2</SB>ingredient and the B<SB>2</SB>O<SB>3</SB>ingredient in the glass. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an optical glass, an optical element, and an optical instrument.

  In recent years, the digitization and high definition of devices that use optical systems have been rapidly progressing, and the precision of optical elements such as lenses used in various optical devices, including photography devices such as digital cameras and video cameras, The demand for light weight and downsizing is increasing.

Among optical glasses for producing optical elements, it has a refractive index (n _d ) of 1.75 or more and 1.84 or less that can reduce the weight and size of the optical element, and 30.0 or more and 55. There is a great demand for high refractive index, low dispersion glass having an Abbe number (ν _d ) of less than or equal to 0.0. As such a high refractive index and low dispersion glass, for example, as an optical glass having a refractive index (n _d ) of 1.74 or more and 1.84 or less and an Abbe number (ν _d ) of 33 or more and 40 or less, a patent Glass compositions represented by Document 1 are known.
JP-A-61-2232243

  As a method for producing such an optical element, a method of grinding and polishing a glass molded product obtained by reheating and molding a glass material (reheat press molding), a preform material obtained by cutting and polishing a gob or a glass block, Alternatively, a method (precise press molding) is used in which a preform material formed by known flotation molding or the like is reheated and pressure-molded with a mold having a highly accurate molding surface.

  However, since the glass disclosed in Patent Document 1 has low thermal stability, the glass softened by heating often crystallizes when the glass is heated. Therefore, using these glasses, when trying to produce an optical element by performing reheat press molding or precision press molding, the optical element is devitrified due to crystallization of the glass, the optical element is milky whitened, The optical properties were affected.

The present invention has been made in view of the above problems, and its object is to achieve high thermal stability while the refractive index (n _d ) and Abbe number (ν _d ) are within the desired ranges. It is to obtain an optical glass having a property, and an optical element and an optical apparatus using the optical glass.

In order to solve the above-mentioned problems, the present inventors have conducted intensive studies and researches. As a result, the glass transition point (Tg) and the crystallization start are obtained by containing the SiO ₂ component and the B ₂ O ₃ component in the glass. the difference in temperature (Tx) becomes large, the thermal stability of the glass is increased, and, SiO _{2 component,} B 2 _{O 3} component, _La 2 _{O 3} component, and a combination of TiO ₂ component, SiO ₂ component In order to complete the present invention, it has been found that by suppressing the content ratios of B ₂ O ₃ component, La ₂ O ₃ component and TiO ₂ component within a predetermined range, the glass can achieve high refractive index and low dispersion. It came. Specifically, the present invention provides the following.

(1) 6.0 to 40.0% of SiO ₂ component, 7.0 to 42.0% of B ₂ O ₃ component, and La ₂ O _{3 in} terms of mass% with respect to the total glass mass of the oxide equivalent composition. An optical glass containing 1.0 to 56.0% of components and 0.1 to 20.0% of TiO ₂ components.

(2) The optical glass according to (1), further containing 0 to 15.0% of an Nb ₂ O ₅ component by mass% with respect to the total glass mass of the oxide equivalent composition.

(3) The optical glass according to (2), wherein a mass ratio (TiO ₂ + Nb ₂ O ₅ ) / (SiO ₂ ) of the oxide equivalent composition is 1.90 or more and 3.00 or less.

(4) MgO component 0 to 15.0% and / or CaO component 0 to 20.0% and / or SrO component 0 to 20.0% and / or% by mass with respect to the total glass mass of the oxide equivalent composition. Or BaO component 0 to 20.0%
The optical glass according to any one of (1) to (3), further comprising:

(5) Weight ratio of the oxide composition in terms of (MgO + CaO + SrO + BaO ) / (SiO 2) is 2.00 or less (4), wherein the optical glass.

(6) The optical glass according to any one of (1) to (5), in which the mass sum SiO ₂ + B ₂ O ₃ with respect to the total glass mass of the oxide conversion composition is 25.0% or more and 60.0% or less.

(7) the weight ratio of the oxide composition in terms of _{(B 2 O 3) / (} SiO 2) is one wherein the optical glass is 1.25 or more 6.50 or less (1) to (6).

(8) The optical glass according to any one of (1) to (7), wherein the mass sum TiO ₂ + Nb ₂ O ₅ with respect to the total glass mass of the oxide equivalent composition is 19.0% or more and 35.0% or less.

  (9) Optical glass in any one of (1) to (8) whose mass sum (MgO + CaO + SrO + BaO) with respect to the glass total mass of an oxide conversion composition is 0 to 45.0%.

(10) ZnO component 0 to 20.0% and / or ZrO ₂ component 0 to 15.0% and / or Gd ₂ O ₃ component 0 to 30% by mass with respect to the total glass mass of the oxide equivalent composition. 0% and / or Y ₂ O ₃ component 0-9.0% and / or Li ₂ O component 0-10.0% and / or Na ₂ O component 0-25.0% and / or K ₂ O component 0 ˜25.0% and / or Ta ₂ O ₅ component 0 to 10.0% and / or WO ₃ component 0 to 10.0% and / or Sb ₂ O ₃ component 0 to 1.0%
The optical glass according to any one of (1) to (9), further containing each component of

  (11) The optical glass according to any one of (1) to (10), which contains substantially no lead compound and arsenic compound.

(12) The refractive index (n _d ) of 1.75 or more and 1.84 or less, and the Abbe number (ν _d ) of 30.0 or more and 55.0 or less, any one of (1) to (11) Optical glass.

  (13) An optical element having the optical glass according to any one of (1) to (12) as a base material.

  (14) An optical element produced by reheat press molding the optical glass according to any one of (1) to (12).

  (15) An optical element produced by precision press-molding a preform made of the optical glass according to any one of (1) to (12).

  (16) An optical device including an optical element made of the optical glass according to any one of (1) to (12).

According to the present invention, by containing the SiO ₂ component and the B ₂ O ₃ component in the glass, the difference between the glass transition point (Tg) and the crystallization start temperature (Tx) is increased, and the thermal stability of the glass. Is increased. Further, the SiO ₂ component, the B ₂ O ₃ component, the La ₂ O ₃ component, and the TiO ₂ component are used in combination, and the contents of the SiO ₂ component, the B ₂ O ₃ component, the La ₂ O ₃ component, and the TiO ₂ component are set as described above. By suppressing the amount within the range, the high refractive index and low dispersion of the glass can be achieved. Therefore, while the refractive index (n _d) and Abbe number ([nu _d) is within the desired range, it has a high thermal stability, and reheated in order to perform the reheat press molding or precision press molding However, it is possible to obtain an optical glass that hardly causes opacification and devitrification in the glass, and an optical element and an optical device using the optical glass.

The optical glass of the present invention is composed of 6.0 to 40.0% of SiO ₂ component and 7.0 to 42.0% of B ₂ O ₃ component in mass% with respect to the total glass mass of the oxide equivalent composition. It contains 1.0 to 56.0% La ₂ O ₃ component and 0.1 to 20.0% TiO ₂ component. By including the SiO ₂ component and the B ₂ O ₃ component in the glass within the above range, the difference between the glass transition point (Tg) and the crystallization start temperature (Tx) is increased, so that the thermal stability of the glass is improved. improves. In addition, the SiO ₂ component, the B ₂ O ₃ component, the La ₂ O ₃ component and the TiO ₂ component are used in combination, and the content rates of the SiO ₂ component, the B ₂ O ₃ component, the La ₂ O ₃ component and the TiO ₂ component are described above. By keeping it within the range, the refractive index of the glass increases and the dispersion of the glass decreases. Therefore, an optical glass having high thermal stability and having a refractive index (n _d ) of 1.75 or more and 1.84 or less and an Abbe number (ν _d ) of 30.0 or more and 55.0 or less. Obtainable.

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

[Glass component]
The composition range of each component constituting the optical glass of the present 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 in terms of oxide. Here, the “oxide equivalent composition” means that the oxide, composite salt, metal fluoride, etc. used as the raw material of the glass component of the present invention are all decomposed and changed into oxides when melted. It is the composition which described each component contained in glass by making the total mass of the said production | generation oxide into 100 mass%.

<About essential and optional components>
The SiO ₂ component is a component that increases the devitrification resistance of the glass and increases the chemical durability of the glass. In particular, when the content of the SiO ₂ component is 6.0% or more, the glass melt can have an appropriate viscosity when molding glass. On the other hand, by setting the content of SiO ₂ component below 40.0%, it is possible to improve the meltability of the glass. Therefore, the content of the SiO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably 6.0%, more preferably 7.0%, and most preferably 8.0%, and preferably 40.0%. %, More preferably 35.0%, and most preferably 30.0%. SiO ₂ component may be contained in the glass by using as a raw material such as _{SiO 2, K 2 SiF 6,} Na 2 SiF 6 or the like.

B ₂ O ₃ component is a component for enhancing the devitrification resistance of the glass. In particular, the devitrification resistance of the desired glass can be easily obtained by setting the content of the B ₂ O ₃ component to 7.0% or more. On the other hand, the content of B ₂ O ₃ component by the following 42.0%, it is possible to easily obtain the refractive index of the desired glass. Therefore, the content ratio of the B ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 7.0%, more preferably 10.0%, and most preferably 12.0%, and preferably 42%. The upper limit is 0.0%, more preferably 35.0%, and most preferably 30.0%. The B ₂ O ₃ component can be contained in the glass using, for example, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ .10H ₂ O, BPO ₄ or the like as a raw material.

In the optical glass of the present invention, the mass sum of the content of the SiO ₂ component and _B 2 _{O 3} component is preferably not less 60.0% 25.0% or more. By making this mass sum 25.0% or more, devitrification of the glass can be reduced. Moreover, a desired refractive index can be easily obtained by setting the mass sum to 60.0% or less. Therefore, the mass sum of the content ratios of the SiO ₂ component and the B ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 25.0%, more preferably 28.0%, and most preferably 30.0. % Is the lower limit, preferably 60.0%, more preferably 58.0%, and most preferably 55.0%.

Further, in the optical glass of the present invention, the weight ratio of the content of _B 2 _{O 3} component to the content of SiO ₂ component is preferably 1.25 or more 6.50 or less. By setting this mass ratio to 1.25 or more, the degree of wear of the glass can be reduced. Moreover, the chemical stability of glass can be improved by making this mass ratio 6.65 or less. The mass ratio of the content ratio of the B ₂ O ₃ component to the content ratio of the SiO ₂ component is preferably 1.25, more preferably 1.50, most preferably 1.75, and preferably 6.50. The upper limit is preferably 5.00, and most preferably 3.50.

The La ₂ O ₃ component is a component that increases the refractive index of the glass and increases the Abbe number of the glass by reducing the dispersion of the glass. In particular, by making the content of the La ₂ O ₃ component 1.0% or more, it is possible to easily obtain a desired high refractive index and low dispersibility. On the other hand, by setting the content of the La ₂ O ₃ component to 56.0% or less, the specific gravity of the glass can be prevented from becoming excessive. Therefore, the content of the La ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 1.0%, more preferably 5.0%, and most preferably 10.0%, and preferably 56%. The upper limit is 0.0%, more preferably 50.0%, and most preferably 45.0%. The La ₂ O ₃ component can be contained in the glass using, for example, La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ O (X is an arbitrary integer) or the like as a raw material.

TiO ₂ component is a component to reduce the specific gravity by increasing the refractive index of the glass. In particular, by making the content of the TiO ₂ component 0.1% or more, it is possible to easily obtain a desired refractive index and specific gravity. On the other hand, by setting the content of the TiO ₂ component to 20.0% or less, the devitrification resistance can be increased and the coloring of the glass can be reduced. Therefore, the content of the TiO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably 0.1%, more preferably 1.0%, and most preferably 5.0% as the lower limit, preferably 20.0. %, More preferably 17.0%, and most preferably 15.0%. TiO ₂ component may be contained in the glass by using as the starting material for example TiO ₂ or the like.

Nb ₂ O ₅ component, and difficult to lower the refractive index of the glass is a component of hard glass devitrification, which is an optional component of the optical glass of the present invention. In particular, by making the content of the Nb ₂ O ₅ component 15.0% or less, the meltability of the glass can be made difficult to deteriorate. Therefore, the content of the Nb ₂ O ₅ component with respect to the total glass mass of the oxide conversion composition is preferably 15.0%, more preferably 12.0%, and most preferably 10.0%. The Nb ₂ O ₅ component can be contained in the glass using, for example, Nb ₂ O ₅ as a raw material.

In the optical glass of the present invention, the mass sum of the content ratios of the TiO ₂ component and the Nb ₂ O ₅ component is preferably 19.0% or more and 35.0% or less. By making this mass sum 19.0% or more, a high refractive index of glass can be easily realized. Moreover, the low dispersibility of glass is realizable by making this mass sum into 35.0% or less. Therefore, the mass sum of the content ratio of the TiO ₂ component and the Nb ₂ O ₅ component with respect to the total glass mass of the oxide conversion composition is preferably 19.0%, more preferably 19.5%, and most preferably 20.0. % Is the lower limit, preferably 35.0%, more preferably 33.0%, and most preferably 31.0%.

Further, the optical glass of the present invention, the mass sum of the TiO ₂ component and _Nb 2 _{O 5} component, the weight ratio SiO ₂ content component is preferably 1.90 or more 3.00 or less. By setting this mass ratio to 1.90 or more, a high refractive index of glass can be realized. By setting the mass ratio to 3.00 or less, it becomes difficult to form microcrystals after vitrification, so that the reheat press property of the glass can be improved. The mass ratio of the mass sum of the TiO ₂ component and the Nb ₂ O ₅ component to the content of the SiO ₂ component is preferably 1.90, more preferably 2.00, and most preferably 2.10. The upper limit is 3.00, more preferably 2.70, and most preferably 2.50.

The MgO component is a component that adjusts the refractive index and dispersion of the glass to reduce the specific gravity of the glass, and is an optional component in the optical glass of the present invention. In particular, by making the content of the MgO component 15.0% or less, a desired refractive index can be easily obtained, and the occurrence of devitrification of the glass can be reduced. Therefore, the content of the MgO component with respect to the total glass mass of the oxide-converted composition is preferably 15.0%, more preferably 10.0%, and most preferably 5.0%. The MgO component can be contained in the glass using, for example, MgCO ₃ or MgF ₂ as a raw material.

A CaO component is a component which adjusts the refractive index and dispersion | distribution of glass, and makes specific gravity of glass small, and is an arbitrary component in the optical glass of this invention. In particular, by setting the content of the CaO component to 20.0% or less, a desired refractive index can be easily obtained, and the occurrence of devitrification of the glass can be reduced. Therefore, the content of the CaO component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 18.0%, and most preferably 16.0%. The CaO component can be contained in the glass using, for example, CaCO ₃ , CaF ₂ or the like as a raw material.

A SrO component is a component which adjusts the refractive index and dispersion | distribution of glass, and improves the devitrification property of glass, and is an arbitrary component in the optical glass of this invention. In particular, by making the content of the SrO component 20.0% or less, a desired refractive index can be easily obtained. Therefore, the content of the SrO component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 10.0%, and most preferably 5.0%. The SrO component can be contained in the glass using, for example, Sr (NO ₃ ) ₂ , SrF ₂ or the like as a raw material.

A BaO component is a component which adjusts the refractive index and dispersion | distribution of glass, and improves the devitrification property of glass, and is an arbitrary component in the optical glass of this invention. In particular, a desired refractive index can be easily obtained by setting the content of the BaO component to 20.0% or less. Accordingly, the content of the BaO component with respect to the total glass mass of the oxide-converted composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. The BaO component can be contained in the glass using, for example, BaCO ₃ , Ba (NO ₃ ) ₂ , BaF ₂ or the like as a raw material.

  In the optical glass of the present invention, 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 45.0% or less. preferable. By making this mass sum 45.0% or less, a desired refractive index can be easily obtained. Therefore, the upper limit of the mass sum of the RO component content is preferably 45.0%, more preferably 40.0%, and most preferably 35.0%.

Further, the optical glass of the present invention, the mass sum of the content of the RO ingredients, the weight ratio SiO ₂ content component, is preferably 2.00 or less. By setting the mass ratio to 2.00 or less, the content of alkaline earth metal that tends to lower the chemical durability can be suppressed, so that the chemical durability of the glass can be improved. The mass ratio of the sum of the RO component content to the SiO ₂ component content is preferably 2.00, more preferably 1.90, and most preferably 1.80.

A ZnO component is a component which raises the refractive index of glass and improves the meltability of glass, and is an arbitrary component in the optical glass of this invention. In particular, when the content of the ZnO component is 20.0% or less, high chemical durability of the glass can be easily obtained. Therefore, the content of the ZnO component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. The ZnO component can be contained in the glass using, for example, ZnO, ZnF ₂ or the like as a raw material.

The ZrO ₂ component is a component that increases the refractive index of the glass and improves the chemical durability, and is an optional component in the optical glass of the present invention. In particular, by making the content of the ZrO ₂ component 15.0% or less, it is possible to make it difficult for the meltability during glass production to deteriorate. Therefore, the content of the ZrO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably 15.0%, more preferably 12.0%, and most preferably 10.0%. The ZrO ₂ component can be contained in the glass using, for example, ZrO ₂ , ZrF ₄ or the like as a raw material.

Gd ₂ O ₃ component, to adjust the refractive index and dispersion of the glass, or to enhance the devitrification resistance of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of the Gd ₂ O ₃ component to 30.0% or less, the amount of the Gd ₂ O ₃ component, which is a rare mineral resource, is reduced, so that the glass material cost can be reduced. . Therefore, the content of the Gd ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 30.0%, more preferably 25.0%, and most preferably 20.0%. The Gd ₂ O ₃ component can be contained in the glass using, for example, Gd ₂ O ₃ , GdF ₃ or the like as a raw material.

Y ₂ O ₃ component, to adjust the refractive index and dispersion of the glass, or to enhance the devitrification resistance of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of the Y ₂ O ₃ component to 9.0% or less, the amount of the Y ₂ O ₃ component that is a rare mineral resource is reduced, so that the material cost of the glass can be reduced. . Therefore, the content of the Y ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 9.0%, more preferably 7.0%, and most preferably 5.0%. The Y ₂ O ₃ component can be contained in the glass using, for example, Y ₂ O ₃ , YF ₃ or the like as a raw material.

Li 2 _O component, while suppressing a decrease in the refractive index of the glass, improves the meltability of the glass, or to enhance the chemical durability of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of the Li ₂ O component to 10.0% or less, it is possible to increase the stability of the glass and reduce the occurrence of devitrification and the like. Therefore, the content of the Li ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 10.0%, more preferably 8.0%, and most preferably 6.0%. The Li ₂ O component can be contained in the glass using, for example, Li ₂ CO ₃ , LiNO ₃ , LiF or the like as a raw material.

Na 2 _O component is a component for improving the meltability of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of Na 2 _O component below 25.0% can be difficult to lower the refractive index of the glass. Therefore, the content of the Na ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 25.0%, more preferably 20.0%, and most preferably 15.0%. The Na ₂ O component can be contained in the glass using, for example, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ or the like as a raw material.

K 2 _O component is a component for improving the meltability of the glass, an optional component of the optical glass of the present invention. In particular, the content of K 2 _O component by below 25.0% can be difficult to lower the refractive index of the glass. Therefore, the content of the K ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 25.0%, more preferably 20.0%, and most preferably 15.0%. The K ₂ O component can be contained in the glass using, for example, K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ or the like as a raw material.

The Ta ₂ O ₅ component is a component that increases the refractive index of the glass and stabilizes the glass, and is an optional component in the optical glass of the present invention. In particular, by making the content of Ta ₂ O ₅ component 10.0% or less, the amount of Ta ₂ O ₅ component, which is a rare mineral resource, is reduced, so the glass material cost can be reduced. . Therefore, the content of the Ta ₂ O ₅ component with respect to the total glass mass of the oxide conversion composition is preferably 10.0%, more preferably 7.0%, and most preferably 5.0%. The Ta ₂ O ₅ component can be contained in the glass using, for example, Ta ₂ O ₅ as a raw material.

The WO ₃ component is a component that adjusts the refractive index and dispersion of the glass and improves the devitrification resistance of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the WO ₃ component to 10.0% or less, the coloration of the glass can be reduced, and the transmittance in the visible-short wavelength region (less than 500 nm) can be made difficult to decrease. Accordingly, the content of the WO ₃ component with respect to the total glass mass of the oxide-converted composition is preferably 10.0%, more preferably 7.0%, and most preferably 5.0%. The WO ₃ component can be contained in the glass using, for example, WO ₃ as a raw material.

The Sb ₂ O ₃ component is a component that defoams the molten glass and is an optional component in the optical glass of the present invention. In particular, by setting the content of _Sb 2 _{O 3} ingredient 1.0% or less, can be hardly caused excessive foaming during glass melting, _Sb 2 _{O 3} ingredient is dissolved facilities (especially noble metal such as Pt ) And alloying can be made difficult. Therefore, the content of the Sb ₂ O ₃ component with respect to the total glass mass of the oxide-converted composition is preferably 1.0%, more preferably 0.8%, and most preferably 0.6%. The Sb ₂ O ₃ component can be contained in the glass using, for example, Sb ₂ O ₃ , Sb ₂ O ₅ , Na ₂ H ₂ Sb ₂ O ₇ · 5H ₂ O, or the like as a raw material.

<About ingredients that should not be included>
Next, components that should not be contained in the optical glass of the present invention and components that are not preferably contained will be described.

Other components can be added as necessary within the range not impairing the properties of the glass of the present invention. However, the transition metal components such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag and Mo, excluding Ti, are colored in the visible region even when they are contained individually or in combination and in small amounts. In particular, in an optical glass using a wavelength in the visible region, it is preferably substantially not contained.

Moreover, since lead compounds such as PbO and arsenic compounds such as As ₂ O ₃ are components with high environmental loads, it is desirable that they are not substantially contained, that is, not contained at all except for inevitable mixing. As a result, the optical glass can be manufactured, processed, and discarded without taking special environmental measures.

  Furthermore, each component of Th, Cd, Tl, Os, Be, and Se has tended to be refrained from being used as a harmful chemical material in recent years, not only in the glass manufacturing process, but also in the processing process and disposal after commercialization. Until then, environmental measures are required. Therefore, when importance is placed on the environmental impact, it is preferable that these are not substantially contained.

The glass composition of the present invention cannot be expressed directly in the description of mol% because the composition is expressed by mass% with respect to the total mass of the glass of oxide conversion composition, but various properties required in the present invention. The composition expressed by mol% of each component present in the glass composition satisfying the above conditions generally takes the following values in terms of oxide conversion.
SiO ₂ component 8.0～50.0Mol% and _B 2 _{O 3} component 8.0～45.0Mol% and _La 2 _{O 3} component 0.3～15.0Mol% and TiO ₂ component 0.1~20.0mol %,
Nb ₂ O ₅ component 0-5.0 mol% and / or MgO component 0-30.0 mol% and / or CaO component 0-30.0 mol% and / or SrO component 0-15.0 mol% and / or BaO component 0～10.0Mol% and / or ZnO component 0～20.0Mol% and / or ZrO ₂ component 0～10.0Mol% and / or _Gd 2 _{O 3} component 0～8.0Mol% and / or _Y 2 _{O 3} component 0～3.0Mol% and / or Li ₂ O component 0～30.0Mol% and / or Na ₂ O component 0～30.0Mol% and / or _{K 2} O ingredient 0～25.0Mol% and / or Ta ₂ O ₅ component 0-2.0 mol% and / or WO ₃ component 0-4.0 mol% and / or Sb ₂ O ₃ component 0-0.3 mol%

[Production method]
The optical glass of the present invention is produced, for example, as follows. That is, the above raw materials are uniformly mixed so that each component is within a predetermined content range, and the prepared mixture is put into a quartz crucible or an alumina crucible and roughly melted, and then a gold crucible, a platinum crucible, a platinum alloy In a crucible or iridium crucible, melt in a temperature range of 1300 to 1400 ° C. for 1 to 10 hours, stir and homogenize, lower to an appropriate temperature, and then cast into a mold or press to form, and gradually It is produced by cooling.

[Physical properties]
The optical glass of the present invention needs to have a high refractive index (n _d ) and low dispersibility (high Abbe number ν _d ). In particular, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.75, more preferably 1.76, most preferably 1.78, and preferably 1.84, more preferably 1.75. 83, most preferably 1.82. Further, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 30.0, more preferably 31.0, and most preferably 32.0, preferably 55.0, more preferably 52. The upper limit is 0, most preferably 49.0. 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.

  Further, the optical glass of the present invention needs to have as high a thermal stability as possible. In particular, the difference ΔT between the glass transition point (Tg) and the crystallization start temperature (Tx) is preferably 110 ° C., more preferably 120 ° C., and most preferably 130 ° C. This suppresses the generation of crystal nuclei and the growth of crystals inside the glass, thereby increasing the thermal stability of the glass. Therefore, when producing an optical element by heating and softening a preform material such as a precision press-molding preform made of the optical glass of the present invention, or by reheat press-molding the optical glass of the present invention to produce an optical element. In this case, it is possible to reduce the influence on the optical characteristics of the optical element including milking and devitrification due to crystallization of glass.

[Optical elements and optical equipment]
As described above, the optical glass of the present invention is useful for various optical elements and optical designs. Among them, in particular, the optical glass of the present invention is used for a lens, a reheat press molding, a precision press molding, or the like. It is preferable to produce an optical element such as a prism. As a result, when used in an optical apparatus such as a camera or a projector, it is possible to reduce the size of the optical system in these optical apparatuses while realizing high-definition and high-precision imaging characteristics and projection characteristics.

Composition of Examples (No. 1 to No. 4) and Comparative Example (No. 1) of the present invention, and the refractive index (n _d ), Abbe number (ν _d ), and glass transition point (Tg) of these glasses. ), The crystallization start temperature (Tx), and the results of the difference (ΔT) between the glass transition point and the crystallization start temperature are shown in Table 1. The following examples are merely for illustrative purposes, and are not limited to these examples.

  The optical glass of Examples (No. 1 to No. 4) of the present invention and the glass of Comparative Example (No. 1) are all oxides, hydroxides, carbonates and nitrates corresponding to the raw materials of the respective components. Select high-purity raw materials used in ordinary optical glass such as fluoride, hydroxide, and metaphosphoric acid compounds, and weigh them so that the composition ratios of the examples and comparative examples shown in Table 1 are obtained. After mixing uniformly, these are put into a platinum crucible, melted in an electric furnace at 1300 to 1400 ° C. for 1 to 10 hours according to the melting difficulty of the glass composition, homogenized with stirring, cast into a mold, and slowly cooled. And glass was produced.

Here, the refractive index (n _d ) and the Abbe number (ν _d ) of the optical glass of the example (No. 1 to No. 4) and the glass of the comparative example (No. 1) are set to -25. It calculated | required by measuring about the glass obtained by setting it at (degreeC / h).

  Moreover, the glass transition point (Tg) and the crystallization start temperature (Tx) of the optical glass of Example (No. 1 to No. 4) and the glass of Comparative Example (No. 1) were measured with a differential heat measuring apparatus (Netchgeretebau). It was determined by carrying out measurements using STA 409 CD). Here, the sample particle size at the time of measurement was set to 425-600 micrometers, and the temperature increase rate was 10 degrees C / min. ΔT was determined from the difference between the glass transition point (Tg) determined above and the crystallization start temperature (Tx).

  As shown in Table 1, in the optical glasses of Examples (Nos. 1 to 4) of the present invention, the difference ΔT between the glass transition point (Tg) and the crystallization start temperature (Tx) is 110 ° C. or more. More specifically, the temperature was 130 ° C. or higher. For this reason, it became clear that the optical glass of the Example of this invention has high thermal stability compared with the glass of a comparative example. In particular, the optical glass of Examples (No. 1 to No. 4) has a ΔT of 150 ° C. or higher, and has a higher ΔT compared to the comparative example (No. 1).

The optical glasses of the examples of the present invention all have a refractive index (n _d ) of 1.75 or more, more specifically 1.78 or more, and this refractive index (n _d ) is 1.84 or less. More specifically, it was 1.82 or less, which was within the desired range. In particular, the optical glass of Examples (No. 1 to No. 4) has a refractive index (n _d ) of 1.78 or more, and has a higher refractive index (n _d ) than that of Comparative Example (No. 1). It became clear to have.

The optical glasses of the examples of the present invention all have an Abbe number (ν _d ) of 30.0 or more, more specifically 32.0 or more, and the Abbe number (ν _d ) of 55.0 or less. More specifically, it was 49.0 or less, and was within the desired range. In particular, the optical glass of the examples (No. 1 to No. 4) has an Abbe number (ν _d ) of 40.0 or less, and has a lower Abbe number (ν _d ) than the comparative example (No. 1). It became clear to have.

Therefore, it was revealed that the optical glass of the example of the present invention has high thermal stability while the refractive index (n _d ) and the Abbe number (ν _d ) are within the desired ranges.

  Furthermore, using the optical glass of Example (No. 1-4) of this invention, after performing reheat press molding, it grind | polished and grind | polished and processed into the shape of a lens and a prism. In addition, a precision press-molding preform was formed using the optical glass of Examples (Nos. 1 to 4) of the present invention, and the precision press-molding preform was precision press-molded. In either case, the glass after heat softening did not cause problems such as opacification and devitrification, and could be stably processed into various lens and prism shapes.

  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 (16)

The SiO ₂ component is 6.0 to 40.0%, the B ₂ O ₃ component is 7.0 to 42.0%, and the La ₂ O ₃ component is 1% by mass with respect to the total mass of the glass in oxide equivalent composition. Optical glass containing 0.0 to 56.0% and 0.1 to 20.0% of TiO ₂ component. The optical glass according to claim 1, further containing 0 to 15.0% of Nb ₂ O ₅ component by mass% with respect to the total mass of the glass having an oxide equivalent composition. 3. The optical glass according to claim 2, wherein the mass ratio (TiO ₂ + Nb ₂ O ₅ ) / (SiO ₂ ) of the oxide equivalent composition is 1.90 or more and 3.00 or less. MgO component 0 to 15.0% and / or CaO component 0 to 20.0% and / or SrO component 0 to 20.0% and / or BaO component in mass% with respect to the total mass of the glass in oxide conversion composition 0 to 20.0%
The optical glass according to claim 1, further comprising: 5. The optical glass according to claim 4, wherein a mass ratio (MgO + CaO + SrO + BaO) / (SiO ₂ ) of the oxide equivalent composition is 2.00 or less. 6. The optical glass according to claim 1, wherein the mass sum SiO ₂ + B ₂ O ₃ with respect to the total glass mass of the oxide conversion composition is 25.0% or more and 60.0% or less.
The optical glass according to any one of claims 1 to 6, wherein the mass ratio (B ₂ O ₃ ) / (SiO ₂ ) of the oxide equivalent composition is 1.25 or more and 6.50 or less. The optical glass according to any one of claims 1 to 7, wherein a mass sum TiO ₂ + Nb ₂ O ₅ is 19.0% or more and 35.0% or less with respect to a total glass mass of an oxide conversion composition.   The optical glass according to any one of claims 1 to 8, wherein a mass sum (MgO + CaO + SrO + BaO) with respect to the total glass mass of the oxide equivalent composition is 0 to 45.0%. ZnO component 0 to 20.0% and / or ZrO ₂ component 0 to 15.0% and / or Gd ₂ O ₃ component 0 to 30.0% by mass% with respect to the total glass mass of the oxide conversion composition / Or Y ₂ O ₃ component 0-9.0% and / or Li ₂ O component 0-10.0% and / or Na ₂ O component 0-25.0% and / or K ₂ O component 0-25. 0% and / or Ta ₂ O ₅ component 0 to 10.0% and / or WO ₃ component 0 to 10.0% and / or Sb ₂ O ₃ component 0 to 1.0%
The optical glass according to claim 1, further comprising:   The optical glass according to claim 1, which contains substantially no lead compound and arsenic compound. The optical glass according to any one of claims 1 to 11, which has a refractive index (n _d ) of 1.75 or more and 1.84 or less and an Abbe number (ν _d ) of 30.0 or more and 55.0 or less.   An optical element using the optical glass according to claim 1 as a base material.   An optical element produced by reheat press molding the optical glass according to claim 1.   An optical element produced by precision press-molding a preform made of the optical glass according to claim 1.   An optical apparatus comprising an optical element made of the optical glass according to claim 1.