JP2010260739A - Optical glass, and optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide optical glass which has a low Abbe number (ν<SB>d</SB>) even though the refractive index (n<SB>d</SB>) thereof is within a desired range, and which is highly transparent to visible light, and in which devitrification and clouding hardly occurs upon production and working of the glass, and from which a preform material and an optical element are easily produced by polishing, and to provide an optical element. <P>SOLUTION: The optical glass contains, in mass% relative to the total mass of the glass in terms of oxides, 5.0 to 40.0% of a P<SB>2</SB>O<SB>5</SB>component and 10.0 to 60.0% of an Nb<SB>2</SB>0<SB>5</SB>component. In the optical glass, the wavelength (λ<SB>70</SB>) at which spectral transmittance shows 70% is ≤500 nm, and the optical glass has a liquid phase temperature of 500 to 1,200°C. Further, the optical element is composed of the optical glass as a matrix. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  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, in particular, it has a high refractive index (n _d ) of 1.70 or more and 2.20 or less, which can reduce the weight and size of the optical element, and is 10 or more and 25 or less. The demand for glass having a high Abbe number (ν _d ) and high refractive index and high dispersion is greatly increasing. As such a high refractive index and high dispersion glass, for example, a glass represented by Patent Document 1 is known as an optical glass having a refractive index (n _d ) of 1.91 or more and an Abbe number of 21 or less. It has been. Further, as an optical glass having a refractive index (n _d ) of 1.65 or more and an Abbe number of 17.2 or more and 33.1 or less, a glass represented by Patent Document 2 is known.

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

  For the production of such optical elements, a method of grinding and polishing molded glass obtained by heat softening a glass material and press molding (reheat press molding), or a preform obtained by cutting and grinding and polishing a gob or glass block There has been used a method (precise press molding) in which a material or a preform material formed by known flotation molding is heated and softened and press-molded with a mold having a highly accurate molding surface.

However, the glass disclosed in Patent Document 1 has a lower transparency to visible light as the Abbe number (ν _d ) is lower (λ ₇₀ is larger), and a glass having a lower Abbe number (ν _d ) is yellow or orange. Is colored. Therefore, even if the glass disclosed in Patent Document 1 has a desired high dispersion, it is not suitable for applications that transmit light in the visible region.

  Further, the glasses disclosed in Patent Documents 1 and 2 have a problem that devitrification is likely to occur when the glass is produced. Furthermore, the glass that is free from devitrification when the glass is produced tends to become cloudy when the glass press-molded by reheat press is polished or when the preform is produced by polishing the glass. There was a problem. It has been difficult to produce an optical element that can control light in the visible region from glass once devitrified or cloudy.

The present invention has been made in view of the above problems, and its object is to have a low Abbe number (ν _d ) while the refractive index (n _d ) is within a desired range, An object of the present invention is to provide an optical glass and an optical element that are highly transparent to visible light, are less likely to be devitrified and cloudy during glass production and processing, and that are easy to produce a preform material and an optical element by polishing. .

In order to solve the above-mentioned problems, the present inventors have conducted intensive test studies, and as a result, the glass has a high refractive index by containing a predetermined amount of P ₂ O ₅ component and Nb ₂ O ₅ component. However, the dispersion was increased to obtain a low Abbe number, the transparency of the glass to visible light was increased, the liquidus temperature of the glass was lowered, and the acid resistance was increased, and the present invention was completed. It came to do. Specifically, the present invention provides the following.

(1) the entire mass of the glass in terms of oxide composition, _P 2 _{O 5} ingredient 40.0% 5.0% or more of the following in mass%, _Nb 2 _{O 5} ingredient 10.0% or more 60.0% Optical glass having a liquidus temperature of 500 ° C. or more and 1200 ° C. or less, having a wavelength (λ ₇₀ ) of 500 nm or less, which is contained below and shows a spectral transmittance of 70%.

(2) TiO ₂ component 0 to 30.0% and / or BaO component 0 to 20.0% and / or SiO ₂ component 0 to 10.0% by mass% with respect to the total glass mass of the oxide equivalent composition
The optical glass according to (1), further comprising:

(3) The optical glass according to (2), wherein the content of the TiO ₂ component is 12.0% or less by mass with respect to the total mass of the glass having an oxide equivalent composition.

  (4) The optical glass according to (2) or (3), wherein the content of the BaO component is 13.0% or less by mass% relative to the total glass mass of the oxide equivalent composition.

(5) as oxide entire mass of the glass composition, the content of SiO ₂ component is less than 2.0% in mass% (2) to (4) any description of the optical glass.

(6) the entire mass of the glass in terms of oxide composition, 0 to 10.0% Li ₂ O component in% by weight and / or Na ₂ O component from 0 to 15.0% and / or _{K 2} O ingredient 0 The optical glass according to any one of (1) to (5), further containing less than 10.0% of each component.

(7) the entire mass of the glass in terms of oxide composition, the content of K _{2 O} component in weight% is 0.1% or more (6), wherein the optical glass.

(8) The optical glass according to (6) or (7), wherein the mass sum Li ₂ O + Na ₂ O + K ₂ O with respect to the total glass mass of the oxide equivalent composition is 15.0% or less.

(9) 0 to 5.0% of MgO component and / or 0 to 10.0% of CaO component and / or 0 to 10.0% of SrO component in mass% with respect to the total glass mass of oxide conversion composition.
The optical glass according to any one of (1) to (8), further comprising:

  (10) The optical glass according to (9), wherein the mass sum MgO + CaO + SrO + BaO is 20.0% or less with respect to the total glass mass of the oxide equivalent composition.

(11) the entire mass of the glass in terms of oxide composition, _Y 2 _{O 3} component from 0 to 10.0% and / or _La 2 _{O 3} component from 0 to 10.0% and / or _Gd 2 _{O 3} in mass% Ingredient 0-10.0%
The optical glass according to any one of (1) to (10), further containing each component of

(12) The optical glass according to (11), wherein the mass sum Y ₂ O ₃ + La ₂ O ₃ + Gd ₂ O ₃ with respect to the total glass mass of the oxide equivalent composition is 20.0% or less.

(13) 0 to 10.0% of B ₂ O ₃ component and / or GeO ₂ component 0 to 10.0% and / or Bi ₂ O ₃ component in mass% with respect to the total glass mass of the oxide equivalent composition 0 ˜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% and / or WO ₃ component 0 to 20.0% and / or Sb ₂ O ₃ component 0 to 1.0%
The optical glass according to any one of (1) to (12), further comprising:

  (14) The optical glass according to any one of (1) to (13), having a refractive index (nd) of 1.70 to 2.20 and an Abbe number (νd) of 10 to 25.

  (15) The optical glass according to any one of (1) to (14), wherein chemical durability (acid resistance) by a powder method is class 1 to 5.

  (16) An optical element made of the optical glass according to any one of (1) to (15).

According to the present invention, by containing a predetermined amount of the P ₂ O ₅ component and the Nb ₂ O ₅ component, the dispersion of the glass is enhanced while the refractive index of the glass is increased, and the visible light of the glass is reduced. Transparency, devitrification resistance and acid resistance are improved. For this reason, the refractive index (n _d ) is within the desired range, but has a low Abbe number (ν _d ), high transparency to visible light, and devitrification and cloudiness during glass production and processing. It is possible to provide an optical glass and an optical element that are less likely to be produced and that facilitate the production of a preform material and an optical element by polishing.

In the optical glass of the present invention, the P ₂ O ₅ component is 5.0% or more and 40.0% or less, and the Nb ₂ O ₅ component is 10.0% or more by mass% with respect to the total glass mass of the oxide equivalent composition. The wavelength (λ ₇₀ ) containing 60.0% or less and having a spectral transmittance of 70% is 500 nm or less, and has a liquidus temperature of 500 ° C. or more and 1200 ° C. or less. While the P ₂ O ₅ component and the Nb ₂ O ₅ component are used in combination, and the content ratio of the P ₂ O ₅ component and the Nb ₂ O ₅ component is kept within a predetermined range, the glass has a high refractive index. Dispersion is enhanced, the transparency of the glass to visible light is increased, the liquidus temperature of the glass is lowered, and the acid resistance of the glass is enhanced so that the glass does not corrode even if it comes into contact with the polishing liquid or cleaning liquid. It becomes difficult to be done. For this reason, the refractive index (n _d ) is within the desired range, but has a low Abbe number (ν _d ), high transparency to visible light, and devitrification and cloudiness during glass production and processing. It is possible to provide an optical glass and an optical element that are less likely to be produced and that facilitate the production of a preform material and an optical element by polishing.

  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 P ₂ O ₅ component is a glass forming component and is a component that lowers the melting temperature of glass. In particular, the transmittance of the glass in the visible region can be increased by setting the content of the P ₂ O ₅ component to 5.0% or more. On the other hand, a desired high refractive index can be obtained by setting the content of the P ₂ O ₅ component to 40.0% or less. Therefore, the content of the P ₂ O ₅ component with respect to the total glass mass of the oxide conversion composition is preferably 5.0%, more preferably 8.0%, and most preferably 10.0%, and preferably 40%. 0.0%, more preferably 35.0%, and most preferably 33.0%. The P ₂ O ₅ component can be contained in the glass using, for example, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , H ₃ PO ₄ or the like as a raw material.

Nb ₂ O ₅ component is a component for increasing the refractive index and dispersion of the glass. In particular, the desired high refractive index and high dispersion can be obtained by setting the content of the Nb ₂ O ₅ component to 10.0% or more. On the other hand, by setting the content of the Nb ₂ O ₅ component to 60.0% or less, devitrification resistance can be improved by suppressing an increase in the liquidus temperature of the glass. 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 20.0%, and most preferably 30.0%, and preferably 60%. 0.0%, more preferably 58.0%, and most preferably 57.0%. The Nb ₂ O ₅ component can be contained in the glass using, for example, Nb ₂ O ₅ as a raw material.

The TiO ₂ component is a component that increases the refractive index and dispersion of the glass and increases chemical durability such as acid 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 TiO ₂ component to 30.0% or less, an increase in the liquidus temperature of the glass can be suppressed and devitrification resistance can be improved. Therefore, the content of the TiO ₂ component with respect to the total glass mass of the 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 glass mass of the oxide conversion composition is preferably 12.0%, in that the transparency to visible light of the glass is particularly enhanced while obtaining a high refractive index and dispersion. More preferably, the upper limit is 11.0%, and most preferably less than 10.0%, but may be less than 5.0% in order to obtain a glass having particularly high transparency to visible light. The TiO ₂ component can be contained in the glass using, for example, TiO ₂ as a raw material.

A BaO component is a component which raises the refractive index of glass, raises the liquidus temperature of glass, and improves devitrification resistance, and is an arbitrary component in the optical glass of this invention. In particular, by making the content of the BaO component 20.0% or less, it becomes easy to obtain a desired high refractive index, suppresses a decrease in devitrification resistance, and decreases chemical durability including acid resistance. Can be suppressed. Therefore, the content of the BaO 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%. Here, in terms of obtaining a glass having a particularly large dispersion (small Abbe number), the content of the BaO component with respect to the total glass mass of the oxide conversion composition is preferably 13.0% as an upper limit, and more preferably 10%. Less than 0.0%, and most preferably 4.5% is the upper limit. 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.

The SiO ₂ component is a component that reduces coloring and increases the transmittance for short-wavelength visible light, and promotes stable glass formation to increase the devitrification resistance of the glass, and is an optional component in the optical glass of the present invention. It is. 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 glass mass of the oxide-converted composition is preferably 10.0%, more preferably 8.0%, and most preferably 6.0%. Here, the content of the SiO ₂ component with respect to the total mass of the glass having an oxide conversion composition is preferably 2.0%, more preferably 1 in that it is easy to obtain a glass having a large dispersion (small Abbe number). .5%, and most preferably 1.0%. SiO ₂ component as a raw material such as _{SiO 2, K 2 SiF 6,} Na 2 SiF 6 and the like can contain in the glass by using.

The Li ₂ O component is a component that lowers the melting temperature of the glass and increases the devitrification resistance at the time of glass formation, and is an optional component in the optical glass of the present invention. In particular, by making the content of the Li ₂ O component 10.0% or less, a desired high refractive index can be easily obtained, and the occurrence of devitrification and the like can be reduced by lowering the liquidus temperature of the glass. . 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 Na ₂ O component is a component that lowers the melting temperature of the glass and increases devitrification resistance at the time of glass formation, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the Na ₂ O component to 15.0% or less, a desired high refractive index can be easily obtained, and the occurrence of devitrification and the like can be reduced by lowering the liquidus temperature 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 15.0%, more preferably 12.0%, and most preferably 10.0%. 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 increased 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%. . 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.

The K ₂ O component is a component that lowers the melting temperature of the glass and increases devitrification resistance during glass formation, and is an optional component in the optical glass of the present invention. In particular, by making the content of the K ₂ O component less than 10.0%, a desired high refractive index can be easily obtained, and the occurrence of devitrification and the like can be reduced by lowering the liquidus temperature 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 less than 10.0%, more preferably 8.0%, and most preferably 6.0%. Although K 2 _O component it is possible to obtain an optical glass having desired properties without containing, by containing K 2 _O ingredient 0.1%, the liquidus temperature of the glass is increased 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%. . 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.

In the optical glass of the present invention, 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 15.0% or less. preferable. Thereby, since the fall of the refractive index of glass is suppressed, it can make it easy to obtain a desired high refractive index. Moreover, since the liquidus temperature of glass becomes low, the devitrification resistance of glass can be improved. Therefore, the mass sum of the content ratio of the Rn ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 15.0%, more preferably 13.0%, and most preferably 12.0%. An optical glass having desired characteristics can be obtained without containing any Rn ₂ O component. However, by containing at least one of the Rn ₂ O components in an amount of 0.1% or more, a glass liquid can be obtained. Since the phase temperature is increased, the devitrification resistance of the glass can be further increased. Therefore, the mass sum of the content ratio of the Rn ₂ O component with respect to the total glass substance amount of the oxide conversion composition in this case is preferably 0.1%, more preferably 1.0%, and most preferably 2.0%. The lower limit.

The MgO component is a component that lowers the liquidus temperature 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, when the content of the MgO component is 5.0% or less, a desired high refractive index and high dispersion can be easily obtained. Accordingly, the content of the MgO component with respect to the total glass mass of the oxide-converted composition is preferably 5.0%, more preferably 4.0%, and most preferably 3.0%. The MgO component can be contained in the glass using, for example, MgCO ₃ or MgF ₂ as a raw material.

The CaO component is a component that lowers the liquidus temperature 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 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 glass mass of the oxide conversion composition is preferably 10.0%, more preferably 8.0%, and most preferably 6.0%. The CaO component can be contained in the glass using, for example, CaCO ₃ , CaF ₂ or the like as a raw material.

The SrO component is a component that lowers the liquidus temperature of the glass and increases the devitrification resistance of the glass, and is an optional component in the glass. 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 glass mass of the oxide conversion composition is preferably 10.0%, more preferably 8.0%, 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.

  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 Mg, Ca, Sr, and Ba) is 20.0% or less. preferable. 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 mass sum of the content ratio of the RO 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%. An optical glass having desired characteristics can be obtained without containing any RO component, but the liquid phase temperature of the glass is increased by containing at least one of the RO components by 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 ratio of the RO component with respect to the total amount of glass in the oxide conversion composition is preferably 0.1%, more preferably 0.5%, and most preferably 1.0%. To do.

The Y ₂ O ₃ component is a component that increases the refractive index 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 making the content of the Y ₂ O ₃ component 10.0% or less, desired high dispersion can be easily obtained, and the devitrification resistance of the glass can be improved. Therefore, the content of the Y ₂ O ₃ 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 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 La ₂ O ₃ component is a component that increases the refractive index 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 making the content of the La ₂ O ₃ component 10.0% or less, desired high dispersion can be easily obtained, and the devitrification resistance of the glass can be improved. Therefore, the content of the La ₂ O ₃ 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 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.

The Gd ₂ O ₃ component is a component that increases the refractive index 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, when the content of the Gd ₂ O ₃ component is 10.0% or less, desired high dispersion can be easily obtained, and the devitrification resistance of the glass can be improved. Therefore, the content of the Gd ₂ O ₃ 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 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.

In the optical glass of the present invention, the mass sum of the contents of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of Y, La, and Gd) is 20.0% or less. Is preferred. By making this mass sum 20.0% or less, an increase in the Abbe number due to the Ln ₂ O ₃ component can be suppressed, so that desired high dispersion can be easily obtained. Therefore, the mass sum of the content ratio of the Ln ₂ O ₃ 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 B ₂ O ₃ component is a component that promotes formation of a stable glass and increases devitrification resistance, and is an optional component in the optical glass of the present invention. In particular, by setting the content of B ₂ O ₃ component to 10.0% or less, the decrease in refractive index due to B ₂ O ₃ component is suppressed, it is possible to easily obtain the desired high refractive index. Therefore, the content of the B ₂ O ₃ 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%. Although B ₂ O ₃ component can be obtained an optical glass having desired properties without containing, by containing B ₂ O ₃ component of 0.1% or more, the liquidus temperature of the glass is increased Therefore, the devitrification resistance of the glass can be further increased. Therefore, in this case, the content of the B ₂ O ₃ component with respect to the total amount of glass in the oxide-converted composition is preferably 0.1%, more preferably 0.2%, and most preferably 0.3%. To do. 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 GeO ₂ component is a component that increases the refractive index of the glass and promotes stable glass formation to increase 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 GeO ₂ component is 10.0% or less, can reduce material costs of the glass. Therefore, the content of the GeO 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 5.0%. The GeO ₂ component can be contained in the glass using, for example, GeO ₂ as a raw material.

Bi ₂ O ₃ component, increasing the refractive index of the glass, or to enhance the dispersion of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of Bi ₂ O ₃ component below 20.0%, to enhance the stability of the glass can suppress a decrease in resistance to devitrification, it is possible to suppress the reduction in the transmittance of the glass it can. Therefore, the content of the Bi ₂ O ₃ component with respect to the total glass mass of the oxide-converted composition is preferably 20.0%, more preferably 15.0%, and even more preferably less than 10.0%. Preferably it is less than 5.0%.

The ZrO ₂ component is a component that reduces coloration and increases the transmittance for visible light with a short wavelength, and promotes stable glass formation to increase the devitrification resistance of the glass. The optional component in the optical glass of the present invention It is. 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 glass mass of the oxide conversion composition is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. The ZrO ₂ component can be contained in the glass using, for example, ZrO ₂ , ZrF ₄ or the like as a raw material.

The ZnO component is a component that lowers the liquidus temperature 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, 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. Therefore, the content of the ZnO 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 ZnO component can be contained in the glass using, for example, ZnO, ZnF ₂ or the like as a raw material.

The Al ₂ O ₃ component is a component that improves the chemical durability of the glass and increases the viscosity when the glass is melted, and is an optional component in the optical glass of the present invention. In particular, by making the content of the Al ₂ O ₃ component 10.0% or less, it is possible to weaken the devitrification tendency of the glass while improving the meltability of the glass. Therefore, the content of the Al ₂ O ₃ 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 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.

Ta ₂ O ₅ 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 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 glass mass of the oxide conversion 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 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 and increases the dispersion 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 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. Accordingly, the content of the WO ₃ 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 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 increases the transmittance of the glass with respect to visible light having a short wavelength and has a defoaming effect when the glass is melted. In particular, by making the content of the Sb ₂ O ₃ component 1.0% or less, it becomes difficult for the Sb ₂ O ₃ component to be alloyed with the melting equipment (especially noble metals such as Pt), and the impurities attached to the mold are reduced. Therefore, the formation of irregularities and cloudiness on the surface of the glass molded body can be reduced. Therefore, the upper limit of the content of the Sb ₂ O ₃ component with respect to the total mass of the oxide 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.

  In addition, each transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo, except Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, is each independently Or, even when it is contained in a small amount in combination, the glass is colored and has the property of causing absorption at a specific wavelength in the visible range. .

  Furthermore, lead compounds such as PbO and components of Th, Cd, Tl, Os, Be, and Se tend to refrain 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.

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.
P ₂ O ₅ component 5.0～40.0Mol% and _Nb 2 _{O 5} component 5.0~30.0mol%,
And TiO ₂ component 0 to 40.0 mol% and / or BaO component 0 to 20.0 mol% and / or SiO ₂ component 0 to 20.0 mol% and / or Li ₂ O component 0 to 30.0 mol% and / or Na ₂ O component 0～30.0Mol% and / or _{K 2} O component 0～15.0Mol% and / or MgO component 0～20.0Mol% and / or CaO component 0～25.0Mol% and / or SrO component 0 ～15.0Mol% and / or _Y 2 _{O 3} component 0～4.0Mol% and / or _La 2 _{O 3} component 0～3.0Mol% and / or _Gd 2 _{O 3} component 0～3.0Mol% and / or B ₂ O ₃ component 0～20.0Mol% and / or GeO ₂ component 0～15.0Mol% and / or _Bi 2 _{O 3} component 0～4.0Mol% and / or ZrO ₂ component 0 13.0 mol% and / or ZnO component 0～20.0Mol% and / or _Al 2 _{O 3} component 0～15.0Mol% and / or _Ta 2 _{O 5} component 0～3.0Mol% and / or WO ₃ ingredient 0 ˜15.0 mol% and / or Sb ₂ O ₃ component 0 to 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 platinum crucible, a platinum alloy crucible or iridium Put in a crucible and melt in the temperature range of 1000-1300 ° C for 2-10 hours, stir to homogenize and blow out bubbles, etc., then lower the temperature to 1250 ° C or lower and then stir to finish to remove striae It is produced by casting into a mold and slow cooling.

[Physical properties]
The optical glass of the present invention needs to have a high refractive index (n _d ) and a high dispersibility. In particular, the refractive index of the optical glass of the present invention _{(n d)} is preferably 1.70, more preferably 1.75, and most preferably with a lower limit on 1.80, preferably 2.20, more preferably 2. 15, most preferably 2.10. The Abbe number (ν _d ) of the optical glass of the present invention 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. The lower limit of the Abbe number (ν _d ) of the optical glass of the present invention is not particularly limited, but the Abbe number (ν _d ) of the glass obtained by the present invention is generally 10 or more, specifically 12 or more, more specifically. In many cases, it is 15 or more.

Moreover, it is preferable that the optical glass of this invention has little coloring. In particular, when the optical glass of the present invention is represented by the transmittance of the glass, the wavelength (λ ₇₀ ) showing a spectral transmittance of 70% in a sample having a thickness of 10 mm is 500 nm or less, more preferably 480 nm or less, and most preferably. Is 450 nm or less. Thereby, the absorption edge of the glass is positioned in the vicinity of the ultraviolet region, and the transparency of the glass in the visible region is enhanced. Therefore, this optical glass can be used as a material for an optical element such as a lens.

  Moreover, the optical glass of the present invention needs to have high devitrification resistance. In particular, the optical glass of 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 of the present invention is preferably 1200 ° C, more preferably 1150 ° C, and most preferably 1100 ° C. As a result, even if the molten glass flows out at a lower temperature, crystallization of the produced glass is reduced, so that the devitrification resistance when the glass is formed from the molten state can be increased. The influence on the optical characteristics of the optical element can be reduced. On the other hand, the lower limit of the liquidus temperature of the optical glass of the present invention is not particularly limited, but the liquidus temperature of the glass obtained by the present invention is approximately 500 ° C. or higher, specifically 550 ° C. or higher, more specifically 600. Often above ℃. As used herein, “liquid phase temperature” refers to a glass sample pulverized to a particle size of about 2 mm on a platinum plate and held in a furnace with a temperature gradient from 800 ° C. to 1220 ° C. for 30 minutes. It is the lowest temperature at which no crystal is observed in the glass and devitrification does not occur, which is measured by observing the presence or absence of crystals in the glass with a microscope with a magnification of 80 after cooling.

  The optical glass of the present invention preferably has high acid resistance. In particular, the chemical durability (acid resistance) of the glass powder method according to JOGIS06-1999 is preferably class 1-5, more preferably class 1-4, and most preferably class 1-3. Thereby, when the optical glass is polished, the fogging of the glass due to the acidic polishing liquid or the cleaning liquid is reduced, so that the polishing process can be more easily performed. Here, “acid resistance” means durability against erosion of glass by acid, and this acid resistance is measured according to the Japan Optical Glass Industry Association Standard “Measurement Method of Chemical Durability of Optical Glass” JOGIS06-1999. Can do. Further, “the chemical durability (acid resistance) by the powder method is class 1 to 5” means that the chemical durability (acid resistance) performed according to JOGIS06-1999 is the mass of the sample before and after the measurement. It means a weight loss rate of less than 2.20% by mass. In addition, “Class 1” of chemical durability (acid resistance) indicates that the weight loss rate of the sample before and after measurement is less than 0.20% by mass, and “Class 2” indicates weight loss of the sample before and after measurement. The rate is 0.20% by mass or more and less than 0.35% by mass, and “Class 3” indicates that the weight loss rate of the sample before and after the measurement is 0.35% by mass or more and less than 0.65% by mass. “4” indicates that the weight loss rate of the sample before and after the measurement is 0.65% by mass or more and less than 1.20% by mass, and “Class 5” indicates that the sample weight loss rate before and after the measurement is 1.20% by mass. The amount is less than 2.20% by mass, and “Class 6” has a mass reduction rate of the sample before and after the measurement of 2.20% by mass or more.

[Production of optical elements]
The optical glass of the present invention is useful for various optical elements and optical designs. Among them, in particular, optical elements such as lenses, prisms, and mirrors are produced from the optical glass of the present invention by means of press molding. It is preferable. As a result, when used in optical devices that transmit visible light to optical elements such as cameras and projectors, the optical system in these optical devices can be miniaturized while realizing high-definition and high-precision imaging characteristics. Can be planned.

Wavelength at which the composition, refractive index (n _d ), Abbe number (ν _d ) and spectral transmittance of the glass of Examples (No. 1 to No. 7) and Comparative Example (No. 1) of the present invention are 70%. Table 1 shows (λ ₇₀ ), liquid phase temperature, and chemical durability (acid resistance) by the powder method. The following examples are merely for illustrative purposes, and are not limited to these examples.

  The optical glass of Examples (No. 1 to No. 7) 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 uniformly mixing, after putting into a platinum crucible, after melting for 2 to 10 hours in a temperature range of 1000 to 1300 ° C. in an electric furnace according to the melting difficulty of the glass composition, stirring and homogenizing, and then blowing out bubbles 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, the refractive index (n _d ) and Abbe number (ν _d ) of the glasses of the examples (No. 1 to No. 7) and the comparative example (No. 1) are the Japan Optical Glass Industry Association Standard JOGIS01-2003. Measured based on The glass used in this measurement was annealed under a slow cooling furnace with a slow cooling rate of −25 ° C./hr.

  Moreover, the liquid phase temperature of the glass of an Example (No.1-No.7) and a comparative example (No.1) puts the grind | pulverized glass sample on a platinum plate at an interval of 10 mm, and this is 800 to 1200 degreeC. The glass sample was held for 30 minutes in a furnace with a temperature gradient and then taken out, and after cooling, the presence or absence of crystals in the glass sample was observed with a microscope with a magnification of 80 times. At this time, the optical glass as a sample was pulverized into particles having a diameter of about 2 mm.

Moreover, about the transmittance | permeability of the glass of an Example (No.1-No.7) and a comparative example (No.1), it measured according to Japan Optical Glass Industry Association standard JOGIS02. In the present invention, the presence / absence and degree of coloration of the glass were determined by measuring the transmittance of the glass. Specifically, a face parallel polished product having a thickness of 10 ± 0.1 mm was measured for a spectral transmittance of 200 to 800 nm in accordance with JISZ8722, and λ ₇₀ (wavelength at a transmittance of 70%) was obtained.

Moreover, the acid resistance of the glass of an Example (No.1-No.7) and a comparative example (No.1) is Japan Optical Glass Industry Association standard "measurement method of the chemical durability of optical glass" JOGIS06-1999. Measured accordingly. That is, a glass sample crushed to a particle size of 425 to 600 μm was taken in a specific gravity bottle and placed in a platinum basket. The platinum basket was placed in a quartz glass round bottom flask containing a 0.01N nitric acid aqueous solution and treated in a boiling water bath for 60 minutes. Calculate the weight loss rate (mass%) of the glass sample after treatment, class 1 when this weight loss ratio (mass%) is less than 0.20, class when the weight loss rate is less than 0.20 to 0.35 2. When the weight loss rate is less than 0.35 to 0.65, class 3, when the weight loss rate is less than 0.65 to 1.20, class 4, and when the weight loss rate is less than 1.20 to 2.20. Class 5 and the weight loss rate of 2.20 or higher were classified as Class 6. At this time, it means that the acid resistance of glass is excellent, so that the number of classes is small.

  As shown in Table 1, the optical glasses of the examples of the present invention all have a liquidus temperature of 1200 ° C. or lower, more specifically less than 1120 ° C., and the liquidus temperature is 500 ° C. or higher. It was. On the other hand, the glass of the comparative example had a liquidus temperature of 1120 ° C. For this reason, it became clear that the optical glass of the Example of this invention has a low liquidus temperature compared with the glass of a comparative example, and is hard to devitrify.

Further, in all of the optical glasses of the examples of the present invention, λ ₇₀ (wavelength at a transmittance of 70%) was 500 nm or less, more specifically 450 nm or less. On the other hand, in the glass of the comparative example, λ ₇₀ was larger than 450 nm. For this reason, it became clear that the optical glass of the Example of this invention was hard to color compared with the glass of a comparative example.

The optical glasses of 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 ) of 2.20 or less. More specifically, it was 2.10 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 10 or more, more specifically 15 or more, and this Abbe number (ν _d ) is 25 or less, and a desired range. It was in.

  Further, the optical glasses of the examples of the present invention all had chemical durability (acid resistance) by the powder method of class 1 to 5, more specifically class 1 to 2. On the other hand, the glass of the comparative example was class 4 in chemical durability (acid resistance) by the powder method. For this reason, it became clear that the optical glass of the Example of this invention is excellent in acid resistance compared with the glass of a comparative example.

  Further, the optical glass of the embodiment of the present invention is cut and polished to form a preform, and this preform is placed in a mold and heated and softened to perform press molding, and the resulting molded body is polished. As a result of processing, the optical glass could be stably processed into various lens shapes.

Therefore, the optical glass of the embodiment of the present invention has high dispersion (low Abbe number ν _d ) while having a refractive index (n _d ) within a desired range, and is transparent to light having a wavelength in the visible region. It has become clear that the glass has high devitrification resistance at the time of glass formation, and that it is difficult for the glass to be fogged when an abrasive ball is produced from the glass.

  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 entire mass of the glass in terms of oxide composition, _P 2 _{O 5} ingredient 40.0% 5.0% or more of the following in mass%, _Nb 2 _{O 5} ingredient containing less 60.0% 10.0% or more An optical glass having a liquidus temperature of 500 ° C. or more and 1200 ° C. or less, with a wavelength (λ ₇₀ ) having a spectral transmittance of 70% of 500 nm or less. TiO ₂ component 0 to 30.0% and / or BaO component 0 to 20.0% and / or SiO ₂ component 0 to 10.0% by mass% with respect to the total glass mass of oxide conversion composition
The optical glass according to claim 1, further comprising: 3. The optical glass according to claim 2, wherein the content of the TiO ₂ component is 12.0% or less by mass% with respect to the total glass mass of the oxide equivalent composition.   The optical glass according to claim 2 or 3, wherein the content of the BaO component is 13.0% or less by mass with respect to the total mass of the glass having an oxide equivalent composition. 5. The optical glass according to claim 2, wherein the content of SiO ₂ component is 2.0% or less by mass with respect to the total glass mass of the oxide equivalent composition. Li ₂ O component 0 to 10.0% and / or Na ₂ O component 0 to 15.0% and / or K ₂ O component 0 to 10.0 by mass% with respect to the total glass mass of the oxide equivalent composition. The optical glass according to claim 1, further comprising less than 1% of each component. The optical glass according to claim 6, wherein the content of the K ₂ O component is 0.1% or more by mass with respect to the total mass of the glass having an oxide equivalent composition. The optical glass according to claim 6 or 7, wherein the total mass Li ₂ O + Na ₂ O + K ₂ O with respect to the total glass mass of the oxide equivalent composition is 15.0% or less. MgO component 0 to 5.0% and / or CaO component 0 to 10.0% and / or SrO component 0 to 10.0% by mass% with respect to the total glass mass of the oxide conversion composition
The optical glass according to claim 1, further comprising:   10. The optical glass according to claim 9, wherein the mass sum MgO + CaO + SrO + BaO is 20.0% or less with respect to the total mass of the glass in an oxide equivalent composition. The entire mass of the glass in terms of oxide composition, from 0 to 10.0% _Y 2 _{O 3} component in% by weight and / or _La 2 _{O 3} component from 0 to 10.0% and / or _Gd 2 _{O 3} component 0 10.0%
The optical glass according to claim 1, further comprising: The optical glass according to claim 11, wherein the sum of masses Y ₂ O ₃ + La ₂ O ₃ + Gd ₂ O ₃ with respect to the total glass mass of the oxide equivalent composition is 20.0% or less. 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 15% by mass with respect to the total glass mass of the oxide equivalent composition. 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 0.0% and / or WO ₃ component 0-20.0% and / or Sb ₂ O ₃ component 0-1.0%
The optical glass according to claim 1, further comprising:   The optical glass according to claim 1, which has 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.   The optical glass according to any one of claims 1 to 14, wherein chemical durability (acid resistance) by a powder method is class 1 to 5.   An optical element made of the optical glass according to claim 1.