JP2009286680A - Optical glass, optical element and optical instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain: optical glass which is high in devitrification resistance when it is formed from a molten state while keeping a refractive index (nd) and an Abbe's number (νd) within a desired range, and to provide an optical element using the same and an optical instrument. <P>SOLUTION: The optical glass contains, by mass, 9.0-50.0% SiO<SB>2</SB>component, 6.0-55.0% B<SB>2</SB>O<SB>3</SB>component, 0.1-5.0% Al<SB>2</SB>O<SB>3</SB>component and 1.2-21.0% CaO component, each based on the total mass of the glass composition in terms of oxide. The optical element is obtained by using the optical glass as a base material. Further, the optical instrument is provided with the optical element. <P>COPYRIGHT: (C)2010,JPO&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 the optical glass for making the optical element has a 1.58 or 1.68 of the refractive index _{(n d),} low dispersion glass having a 47.0 or 62.0 or less Abbe number ([nu _d) The demand for has increased greatly. As such a low dispersion glass, for example, Patent Document 1 has a refractive index (n _d ) of 1.58 to 1.67 and an Abbe number (ν _d ) of 50.0 to 62.0. Glass compositions represented by the above are known.
Japanese Patent Laid-Open No. 04-037628

  Such optical element manufacturing methods include a method of grinding and polishing a glass molded product obtained by heating and softening a glass material (reheat press molding), a preform material obtained by cutting and polishing a gob or glass block, Alternatively, a method (precise press molding) is used in which a preform material molded by a known floating molding or the like is heated and softened and pressure-molded with a mold having a highly accurate molding surface.

  However, it is necessary to suppress the crystallization of the glass component in order to suppress the devitrification of the glass, and in order to suppress the crystallization of the glass component, it is preferable that the difference between the temperature at the time of pressing and the temperature at which crystallization starts is large. That is, where the difference ΔT between the crystallization start temperature (Tx) and the glass transition point (Tg) needs to be large, the glass disclosed in Patent Document 1 does not have a large difference ΔT from the crystallization start temperature (Tx). It was easy to devitrify during pressing. Therefore, even if trying to produce a glass material for reheat press molding or a gob or glass block for precision press molding from these molten glasses, the glass is devitrified, and optical elements are produced from these glasses. It was difficult.

The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to make glass from a molten state while the refractive index (n _d ) and Abbe number (ν _d ) are within the desired ranges. It is to obtain an optical glass having high resistance to devitrification when an optical element is formed, an optical element and an optical instrument using the optical glass.

In order to solve the above-mentioned problems, the present inventors have conducted intensive test studies. As a result, the SiO ₂ component, the B ₂ O ₃ component, the Al ₂ O ₃ component, and the CaO component are used in combination, and the B ₂ O ₃ component is used. , SiO ₂ component, B ₂ O ₃ component, La ₂ O ₃ component, and ZnO component content is suppressed within a predetermined range, the refractive index and dispersion of the glass is within the desired range, the glass transition point The inventors have found that the difference ΔT between (Tg) and the crystallization start temperature (Tx) becomes large, and have completed the present invention. Specifically, the present invention provides the following.

(1) 9.0 to 50.0% of SiO ₂ component, 6.0 to 55.0% of B ₂ O ₃ component, and Al ₂ O _{3 in} terms of mass% with respect to the total glass mass of the oxide equivalent composition. Optical glass containing 0.1 to 5.0% of components and 1.2 to 21.0% of CaO components.

(2) 0 to 20.0% of ZnO component and / or 0 to 10.0% of MgO component and / or 0 to 5.5% of SrO component and / Or BaO component 0-55.0%
(1) optical glass which further contains each component of.

(3) the weight ratio of the oxide composition in terms of (ZnO + MgO + CaO + SrO + BaO) / (SiO 2 + B 2 O 3 + Al 2 O 3) is 0.33 to 1.50 (2), wherein the optical glass.

(4) Na ₂ O component 0 to 20.0% and / or K ₂ O component 0 to 17.0% and / or TiO ₂ component 0 to 10% by mass with respect to the total glass mass of the oxide equivalent composition 0.02% and / or La ₂ O ₃ component 0-28.0%
The optical glass according to any one of (1) to (3), further comprising:

(5) The mass sum (SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ + ZnO + MgO + CaO + SrO + BaO + Na ₂ O + K ₂ O + TiO ₂ + La ₂ O ₃ ) with respect to the total glass mass of the oxide conversion composition is 90.0% or more. Optical glass.

  (6) Optical glass in any one of (1) to (5) which does not contain a lead compound and an arsenic compound substantially.

  (7) Optical glass in any one of (2) to (6) whose mass sum (ZnO + MgO + CaO + SrO + BaO) with respect to the glass total mass of an oxide conversion composition is 2.0% or more and 60.0% or less.

(8) 0 to 15.0% of ZrO ₂ component and / or Nb ₂ O ₅ component 0 to 10.0% and / or Y ₂ O ₃ component 0% by mass with respect to the total glass mass of the oxide equivalent composition 15.0% and / or _Gd 2 _{O 3} component from 0 to 15.0% and / or _Yb 2 _{O 3} component from 0 to 8.0% and / or _Lu 2 _{O 3} component from 0 to 8.0% and / or Li ₂ O component 0 to 10.0% and / or Ta ₂ O ₅ component 0 to 8.0% and / or WO ₃ component 0 to 8.0% and / or Sb ₂ O ₃ component 0 to 1.0%
The optical glass according to any one of (1) to (7), further containing each component of:

(9) 1.58 or 1.68 of the refractive index has _{(n d),} according to any of having (1) a 47.0 or 62.0 or less Abbe number ([nu _d) (8) Optical glass.

  (10) An optical element having the optical glass according to any one of (1) to (9) as a base material.

  (11) An optical element produced by reheat press molding the optical glass according to any one of (1) to (9).

  (12) An optical element produced by precision press-molding a preform made of the optical glass according to any one of (1) to (9).

  (13) An optical device including an optical element made of the optical glass according to any one of (1) to (9).

According to the present invention, the SiO ₂ component, the B ₂ O ₃ component, the Al ₂ O ₃ component, and the CaO component are used in combination, and the B ₂ O ₃ component, the SiO ₂ component, the B ₂ O ₃ component, and the Al ₂ O ₃ component are combined. And by suppressing the content of the CaO component within a predetermined range, the loss resistance when the glass is formed from a molten state while the refractive index (n _d ) and the Abbe number (ν _d ) are within the desired ranges. An optical glass with high permeability, an optical element and an optical instrument using the optical glass can be obtained.

In the optical glass of the present invention, the SiO ₂ component is 9.0 to 50.0% and the B ₂ O ₃ component is 6.0 to 55.0% by mass% with respect to the total mass of the oxide-converted glass. It contains 0.1 to 5.0% of Al ₂ O ₃ component and 1.2 to 21.0% of CaO component. Containing SiO ₂ component, B ₂ O ₃ component, Al ₂ O ₃ component, and CaO component together, containing B ₂ O ₃ component, SiO ₂ component, B ₂ O ₃ component, Al ₂ O ₃ component, and CaO component By controlling the rate within a predetermined range, the refractive index and dispersion of the glass are within a desired range, the difference ΔT between the glass transition point (Tg) and the crystallization start temperature (Tx) is increased, and the glass crystal The crystallization peak temperature decreases. For this reason, the refractive index (n _d ) is in the range of 1.58 or more and 1.68 or less, and the Abbe number (ν _d ) is in the range of 47.0 or more and 62.0 or less. An optical glass having a high devitrification resistance when forming can be obtained.

  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 forms a network structure inside the glass, promotes stable glass formation, and devitrification (generation of crystals) and striae (nonuniformity inside the glass) when producing an unfavorable glass as an optical glass. Property). In particular, the devitrification resistance of the glass can be improved by setting the content of the SiO ₂ component to 9.0% or more. On the other hand, by setting the content of SiO ₂ component below 50.0% it can be difficult to lower the refractive index 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 9.0%, more preferably 9.5%, and most preferably 10.0%, and preferably 50.0%. %, More preferably 48.0%, and most preferably 45.0%. 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.

The B ₂ O ₃ component is a component that forms a network structure inside the glass and promotes stable glass formation. In particular, by setting the content of the B ₂ O ₃ component to 6.0% or more, the glass is hardly devitrified and a stable glass can be easily obtained. On the other hand, the content of B ₂ O ₃ component by the following 55.0%, can be difficult to lower the refractive index of the 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 6.0%, more preferably 6.5%, and most preferably 6.8%, and preferably 55%. 0.0%, more preferably 53.0%, and most preferably 50.0%. 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.

The Al ₂ O ₃ component is a component that improves the stability of the glass and improves the devitrification resistance when the glass is produced from molten glass. In particular, the stability of the glass can be remarkably enhanced by setting the content of the Al ₂ O ₃ component to 0.1% or more. On the other hand, by the content of Al ₂ O ₃ component to 5.0% or less, it is possible to suppress a decrease in the refractive index of the glass. Therefore, the content ratio of the Al ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 0.1%, more preferably 0.2%, and most preferably 0.3% as the lower limit, preferably 5 The upper limit is 0.0%, more preferably 4.8%, and most preferably 4.7%. The Al ₂ O ₃ component can be contained in the glass using, for example, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ or the like as a raw material.

The CaO component is a component that adjusts the refractive index of the glass. In particular, by setting the content of the CaO component to 1.2% or more, desired optical characteristics of the glass can be easily obtained, and the specific gravity of the glass can be reduced. On the other hand, the refractive index of glass can be made hard to fall by making the content rate of a CaO component into 21.0% or less. Therefore, the content of the CaO component with respect to the total glass mass of the oxide conversion composition is preferably 1.2%, more preferably 1.5%, and most preferably 2.0% as the lower limit, preferably 21.0%. More preferably, the upper limit is 20.8%, and most preferably 20.6%. The CaO component can be contained in the glass using, for example, CaCO ₃ , CaF ₂ or the like as a raw material.

A ZnO component is a component which improves the meltability of glass, and is an arbitrary component in the optical glass of this invention. In particular, by setting the content of the ZnO component to 20.0% or less, the transmittance on the short wavelength side in the visible region can be increased. Therefore, the content of the ZnO component with respect to the total glass mass of the oxide-converted composition is preferably 20.0%, more preferably 18.0%, and most preferably 15.0%. The ZnO component can be contained in the glass using, for example, ZnO, ZnF ₂ or the like as a raw material.

The MgO component is a component that adjusts the refractive index of the glass, and is an optional component in the optical glass of the present invention. In particular, when the content of the MgO component is 10.0% or less, desired optical characteristics of the glass can be easily obtained. Therefore, the content of the MgO component with respect to the total glass mass of the oxide-converted composition is preferably 10.0%, more preferably 8.0%, 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 SrO component is a component which adjusts the refractive index of glass, and is an arbitrary component in the optical glass of this invention. In particular, when the content of the SrO component is 5.5% or less, desired optical characteristics of the glass 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 5.5%, more preferably 5.2%, and most preferably 4.9%. 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.

The BaO component is a component that increases the refractive index of the glass to realize an appropriate Abbe number and realizes a high internal transmittance, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the BaO component to 55.0% or less, the devitrification resistance of the glass can be increased, and the chemical durability of the glass can be increased. Therefore, the content of the BaO component with respect to the total glass mass of the oxide-converted composition is preferably 55.0%, more preferably 54.0%, and most preferably 53.0%. The BaO component can be contained in the glass using, for example, BaCO ₃ , Ba (NO ₃ ) ₂ or the like as a raw material.

  In the optical glass of the present invention, the mass sum of the content ratio of the RO component (wherein R is one or more selected from the group consisting of Zn, Mg, Ca, Sr, and Ba) is 2.0% or more and 60.60. It is preferably 0% or less. By making this mass sum 2.0% or more, the stability of the glass can be enhanced and the devitrification resistance of the glass can be enhanced. Moreover, the desired optical characteristic of glass can be easily obtained by making this mass sum 60.0% or less. Therefore, the mass sum of the content of the RO component with respect to the total glass mass of the oxide conversion composition is preferably 2.0%, more preferably 5.0%, and most preferably 8.0%, and preferably 60%. The upper limit is 0.0%, more preferably 58.0%, and most preferably 55.0%.

Further, the optical glass of the present invention, it is preferable mass ratio of the content of the RO component relative to the mass sum _{(SiO 2 + B 2 O 3} + Al 2 O 3) is 0.33 to 1.50. By making this mass ratio 0.35 or more, the stability of the glass can be increased and the devitrification resistance when the glass is formed from the molten state can be increased. Moreover, by making this mass ratio 1.50 or less, it is easy to form a network structure of glass, and vitrification can be facilitated. Therefore, the mass ratio of the content of the RO component to the mass sum (SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ ) of the oxide equivalent composition is preferably 0.33, more preferably 0.34, and most preferably 0.8. 35 is the lower limit, preferably 1.50, more preferably 1.40, and most preferably 1.30.

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 the Na ₂ O component to 20.0% or less, it is possible to make it difficult for the refractive index of the glass to decrease, to increase the stability of the glass, and to prevent devitrification and the like. Therefore, the content of the Na ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 18.0%, 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, by setting the content of the K ₂ O component to 17.0% or less, the refractive index of the glass is hardly lowered, the stability of the glass is increased, and devitrification or the like is hardly caused. Therefore, the content of the K ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 17.0%, more preferably 15.0%, and most preferably 13.0%. 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 TiO ₂ component is a component that increases the chemical durability of the glass and adjusts the refractive index and dispersion, and is an optional component in the optical glass of the present invention. In particular, by making the content of the TiO ₂ component 10.0% or less, it is possible to reduce the coloration of the glass and to make it difficult to deteriorate the transmittance particularly in the visible short wavelength (500 nm or less). Therefore, the content of the TiO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably 10.0%, more preferably 8.0%, and most preferably 7.0%. TiO ₂ component may be contained in the glass by using as the starting material for example TiO ₂ or the like.

The La ₂ O ₃ component is a component that increases the refractive index of the glass to reduce dispersion and realizes high internal transmittance of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the La ₂ O ₃ component to 28.0% or less, the devitrification resistance when glass is formed from the molten state can be further increased, and a desired optical constant can be easily obtained. . Therefore, the content of the La ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 28.0%, more preferably 25.0%, and most preferably 22.0%. 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.

In the optical glass of the present invention, SiO ₂ component, B ₂ O ₃ component, Al ₂ O ₃ component, ZnO component, MgO component, CaO component, SrO component, BaO component, Na ₂ O component, K ₂ O component, TiO ₂ component, and the mass sum of _La 2 _{O 3} component content is is preferably 90.0% or more. By making this mass sum 90.0% or more, it is possible to increase the meltability of the glass and reduce the manufacturing cost of the glass while enhancing the stability of the glass and the devitrification resistance of the glass. Therefore, this mass sum with respect to the total glass mass of the oxide conversion composition is preferably 90.0%, more preferably 95.0%, and most preferably 98.0%.

The ZrO ₂ component is a component that increases the refractive index of the glass and increases the devitrification resistance of the glass, 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 easily obtain a desired optical constant, to lower the melting temperature of the glass, and to reduce the cost due to energy loss at the time of glass production. . 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 13.0%, 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.

Nb ₂ O ₅ component increases the refractive index of the glass is a component for improving the chemical durability of the glass, an optional component of the optical glass of the present invention. In particular, by making the content of the Nb ₂ O ₅ component 10.0% or less, it is easy to obtain a desired optical constant, lower the melting temperature of the glass, and reduce the cost due to energy loss during glass production. Can do. Therefore, the content of the Nb ₂ O ₅ component with respect to the total glass mass of the oxide conversion composition is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. The Nb ₂ O ₅ component can be contained in the glass using, for example, Nb ₂ O ₅ as a raw material.

Y ₂ O ₃ component is a component to decrease the dispersion by increasing the refractive index 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 15.0% or less, it is possible to reduce the material cost of the glass and make it difficult to devitrify the glass when producing the glass. Therefore, the content of the Y ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 15.0%, more preferably 13.0%, and most preferably 10.0%. 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.

The Gd ₂ O ₃ component is a component that increases the refractive index of the glass and decreases dispersion, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the Gd ₂ O ₃ component to 15.0% or less, it is possible to reduce the material cost of the glass and make it difficult to devitrify the glass when producing the glass. Therefore, the content of the Gd ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 15.0%, more preferably 13.0%, and most preferably 10.0%. 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.

Yb ₂ O ₃ component is a component that raises the refractive index of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of Yb ₂ O ₃ component to 8.0% or less, it is possible to reduce the material cost of the glass. Therefore, the upper limit of the content of the Yb ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 8.0%, more preferably 6.0%, and most preferably 5.0%. The Yb ₂ O ₃ component can be contained in the glass using, for example, Yb ₂ O ₃ as a raw material.

Lu ₂ O ₃ component is a component to decrease the dispersion by increasing the refractive index of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of Lu ₂ O ₃ component to 8.0% or less, it is possible to reduce the material cost of the glass. Therefore, the upper limit of the content of the Lu ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 8.0%, more preferably 6.0%, and most preferably 5.0%. The Lu ₂ O ₃ component can be contained in the glass using, for example, Lu ₂ O ₃ as a raw material.

Li 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 making the content of the Li ₂ O component 10.0% or less, the refractive index of the glass is hardly lowered, the stability of the glass is increased, and devitrification or the like is hardly caused. Therefore, the upper limit of the content ratio 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 5.0%. 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.

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 the Ta ₂ O ₅ component 8.0% or less, it is possible to reduce the material cost of the glass and avoid melting at a high temperature to reduce energy loss during glass production. . Therefore, the content of the Ta ₂ O ₅ component with respect to the total glass mass of the oxide conversion composition is preferably 8.0%, more preferably 6.0%, 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 increases the refractive index of the glass, increases the dispersion of the glass, and improves the chemical durability 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 8.0% or less, it is possible to make it difficult to deteriorate the transmittance particularly at a visible short wavelength (500 nm or less). Therefore, the content of the WO ₃ component with respect to the total glass mass of the oxide-converted composition is preferably 8.0%, more preferably 6.0%, 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 ingredients below 1.0%, and less likely to deteriorate the transmittance in the visible short wavelength, and less likely to occur excessive foaming during glass melting, Sb ₂ O ₃ component Can be made difficult to alloy with melting equipment (especially noble metals such as Pt). 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 0.5%. 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.

Incidentally, components defoamed fining glass is not limited to the above Sb ₂ O ₃ component, a known refining agents in the field of glass production, it is possible to use a defoamer or a combination thereof.

<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.

  If necessary, other components can be added to the optical glass of the present invention as long as the properties of the glass of the present invention are not impaired.

  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.

Furthermore, lead compounds such as PbO, arsenic compounds such as As ₂ O ₃ , and components of Th, Cd, Tl, Os, Be, and Se have been refraining from being used as harmful chemical substances in recent years. Environmental measures are required not only in the manufacturing process but also in the processing process and 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 any special environmental measures.

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 13.0～60.0Mol% and _B 2 _{O 3} component 6.0～60.0Mol% and _Al 2 _{O 3} component 0.1 to 5.0 mol% and CaO components 2.0～30.0Mol%
And ZnO ingredients 0～20.0Mol% and / or MgO component 0～20.0Mol% and / or SrO component 0～4.0Mol% and / or BaO component 0～35.0Mol% and / or Na ₂ O component 0 ˜25.0 mol% and / or K ₂ O component 0 to 15.0 mol% and / or TiO ₂ component 0 to 10.0 mol% and / or La ₂ O ₃ component 0 to 6.0 mol% and / or ZrO ₂ component 0～10.0Mol% and / or _Nb 2 _{O 5} component 0～3.0Mol% and / or _Y 2 _{O 3} component 0～5.0Mol% and / or _Gd 2 _{O 3} component 0～4.0Mol% and / or _Yb 2 _{O 3} component 0～2.0Mol% and / or _Lu 2 _{O 3} component 0～2.0Mol% and / or Li ₂ O component 0～25.0Mol% and / or _Ta 2 _{O 5} component ～1.5Mol% and / or WO ₃ components 0～3.0Mol% and / or _Sb 2 _{O 3} component 0～0.3Mol%

[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 platinum crucible, a quartz crucible or an alumina crucible and roughly melted, then a gold crucible, a platinum crucible In a platinum alloy crucible or iridium crucible, melt in a temperature range of 1300 to 1350 ° C. for 3 to 4 hours, stir and homogenize, blow out bubbles, etc., then lower the temperature to 1200 ° C. or lower and perform final stirring It is manufactured by removing the striae, casting into a mold and slow cooling.

[Physical properties]
The optical glass of the present invention needs to have a desired refractive index (n _d ) and low dispersion (high Abbe number). In particular, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.58, more preferably 1.60, and most preferably 1.61, preferably 1.68, more preferably 1. 67, most preferably 1.66. Further, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 47.0, more preferably 48.0, most preferably 49.0, preferably 62.0, more preferably 61. The upper limit is 0, most preferably 60.5. 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.

  The optical glass of the present invention has high devitrification resistance when glass material is heated and softened to perform molding (reheat press molding), and high devitrification resistance when glass is formed from a molten state. It is preferable. More specifically, the difference ΔT between the glass transition point (Tg) and the crystallization start temperature (Tx) of the optical glass of the present invention is preferably 50 ° C., more preferably 55 ° C., and most preferably 60 ° C. And The exothermic peak temperature due to crystallization when the temperature is lowered from the melt obtained by performing differential thermal analysis (DTA) on the optical glass of the present invention is preferably 780 ° C., more preferably 770 ° C., most preferably 765 ° C. Is the upper limit. These increase the thermal stability of the glass and reduce the generation of crystal nuclei of the glass component, and also reduce the growth of crystal of the glass component even when the molten glass flows out at a lower temperature to form the glass. Therefore, the influence on the optical characteristics of the glass due to devitrification can be reduced.

[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. Thereby, when used in an optical apparatus such as a camera or a projector, it is possible to realize high-definition and high-precision imaging characteristics and projection characteristics.

Composition of Examples (No. 1 to No. 18) 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. ), Crystallization start temperature (Tx), difference between glass transition point and crystallization start temperature (ΔT), and crystallization peak temperature results are shown in Tables 1 and 2. The following examples are merely for illustrative purposes, and are not limited to these examples.

  The optical glass of Examples (No. 1 to No. 18) 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 fluorides, hydroxides, metaphosphoric acid compounds, etc., so that the composition ratios of the examples and comparative examples shown in Tables 1 and 2 are obtained. After weighing and mixing uniformly, it is put in a platinum crucible and melted in a temperature range of 1300 to 1350 ° C. for 3 to 4 hours in accordance with the melting difficulty of the glass composition, and homogenized by stirring to remove bubbles. Then, the temperature was lowered to 1150 ° C. or lower, and the mixture was homogenized with stirring, cast into a mold, and slowly cooled to produce glass.

Here, the refractive index (n _d ) and the Abbe number (ν _d ) of the optical glass of Example (No. 1 to No. 18) and the glass of 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 Examples (No. 1 to No. 18) and the glass of Comparative Example (No. 1) were measured with a differential heat measuring device (Netchgeretebau). It was determined by carrying out measurement using STA 409 CD manufactured by the company. 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). Furthermore, after the temperature is raised to 1200 ° C. to make it completely melted, the exothermic peak temperature due to crystallization at the time of cooling to 300 ° C. is measured at a temperature drop rate of 10 ° C./min. The crystallization peak temperature from the liquid was measured.

  As shown in Tables 1 and 2, the optical glasses of the examples of the present invention were measured using differential thermal analysis (DTA), and ΔT was 50 ° C. or higher, more specifically 62 ° C. or higher. It was. On the other hand, ΔT of the glass of the comparative example was less than 50 ° C. In all cases, the crystallization peak temperature from the melt was 770 ° C. or lower, more specifically 763 ° C. or lower. On the other hand, the glass of the comparative example had a crystallization peak temperature higher than 770 ° C. For this reason, the optical glass of the example of the present invention is less likely to generate crystal nuclei of the glass component than the glass of the comparative example, and it is difficult for crystals to grow from the crystal nuclei. Became clear.

The optical glasses of the examples of the present invention all have a refractive index (n _d ) of 1.58 or more, more specifically 1.61 or more, and the refractive index (n _d ) of 1.68 or less. More specifically, it was 1.66 or less, and was within the desired range.

The optical glasses of the examples of the present invention all have an Abbe number (ν _d ) of 47.0 or more, more specifically 49.0 or more, and the Abbe number (ν _d ) of 62.0 or less. More specifically, it was 60.5 or less, and was within the desired range.

Therefore, the optical glass of the embodiment of the present invention has high devitrification resistance when the glass is formed from a molten state while the refractive index (n _d ) and Abbe number (ν _d ) are within the desired ranges. Became clear.

  Furthermore, using the optical glass of the example of the present invention, after performing reheat press molding, grinding and polishing were performed to process into the shape of a lens and a prism. Further, a precision press-molding preform was formed using the optical glass of the example of the present invention, and the precision press-molding preform was precision press-molded. In any case, problems such as opacification and devitrification did not occur in the glass after heat softening, and it 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 (13)

The SiO ₂ component is 9.0 to 50.0%, the B ₂ O ₃ component is 6.0 to 55.0%, and the Al ₂ O ₃ component is 0% by mass with respect to the total mass of the oxide-converted glass. An optical glass containing 1 to 5.0% and 1.2 to 21.0% CaO component. ZnO component 0 to 20.0% and / or MgO component 0 to 10.0% and / or SrO component 0 to 5.5% and / or BaO component in mass% with respect to the total mass of the glass in oxide conversion composition 0-55.0%
The optical glass according to claim 1, further comprising: _3. The optical glass according to claim 2, wherein a mass ratio (ZnO + MgO + CaO + SrO + BaO) / (SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ ) of the oxide equivalent composition is 0.33 or more and 1.50 or less. Na ₂ O component 0 to 20.0% and / or K ₂ O component 0 to 17.0% and / or TiO ₂ component 0 to 10.0% by mass% with respect to the total glass mass of oxide conversion composition And / or La ₂ O ₃ component 0 to 28.0%
The optical glass according to claim 1, further comprising: 5. The optical glass according to claim 4, wherein a mass sum (SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ + ZnO + MgO + CaO + SrO + BaO + Na ₂ O + K ₂ O + TiO ₂ + La ₂ O ₃ ) with respect to the total mass of the glass in terms of oxide is 90.0% or more.   6. 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 2 to 6, wherein a mass sum (ZnO + MgO + CaO + SrO + BaO) with respect to the total mass of the glass in terms of an oxide is 2.0% or more and 60.0% or less. ZrO ₂ component 0 to 15.0% and / or Nb ₂ O ₅ component 0 to 10.0% and / or Y ₂ O ₃ component 0 to 15% by mass with respect to the total glass mass of the oxide equivalent composition. 0% and / or Gd ₂ O ₃ component 0 to 15.0% and / or Yb ₂ O ₃ component 0 to 8.0% and / or Lu ₂ O ₃ component 0 to 8.0% and / or Li ₂ O Component 0 to 10.0% and / or Ta ₂ O ₅ component 0 to 8.0% and / or WO ₃ component 0 to 8.0% 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 has a refractive index (n _d ) of 1.58 or more and 1.68 or less and an Abbe number (ν _d ) of 47.0 or more and 62.0 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.