JP2010260742A - Optical glass, optical element, and preform for precision press molding - 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, is highly transparent to visible light, and is easily softened upon heating, and to provide an optical element and a preform for precision press molding. <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. The content of a TiO<SB>2</SB>component is <10.0%, and the optical glass has a glass transition point (Tg) of ≤700°C. The optical element and the preform for precision press molding are composed of the optical glass. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical glass, an optical element, and a precision press-molding preform.

  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

  When producing an optical element using such glass, a method of grinding and polishing a glass molded product obtained by heat softening and press molding (reheat press molding), or cutting and polishing a gob or a glass block The preform material or the preform material formed by known flotation molding is heat-softened and press-molded with a mold having a highly accurate molding surface (precision press molding).

  However, many of the glasses disclosed in Patent Documents 1 and 2 have a high glass transition point (Tg), and these glasses are difficult to soften even when heated. For this reason, when a preform material is produced from the glass of Patent Document 1, and an optical element is produced by heat-softening and press-molding the preform material, it is necessary to heat-soften the preform material and increase the temperature for press-molding. For this reason, the die used for press molding and the preform material are fused, and the optical characteristics of the optical element are affected.

Furthermore, 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.

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, an optical element, and a precision press-molding preform that are highly transparent to visible light and are easily softened at a low temperature.

In order to solve the above-mentioned problems, the present inventors have conducted extensive test studies. As a result, the P ₂ O ₅ component and the Nb ₂ O ₅ component are used in combination, and the P ₂ O ₅ component, the Nb ₂ O ₅ component, and the TiO _By suppressing the content of the _two components within a predetermined range, the glass has a high refractive index, but the dispersion is increased to obtain a low Abbe number, and the transparency of the glass to visible light is enhanced. And it discovered that a glass transition point (Tg) became low, and came to complete this invention. 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% It contains the following, a content of TiO ₂ component is less than 10.0%, the optical glass having 700 ° C. or less of the glass transition point (Tg).

(2) 0 to 30.0% of BaO component in mass% with respect to the total glass mass of oxide equivalent composition
(1) The optical glass which contains further.

  (3) The optical glass according to (2), wherein the content of the BaO component is 1.0% or more and less than 17.0% by mass% with respect to the total glass mass of the oxide equivalent composition.

(4) the entire mass of the glass in terms of oxide composition, 0 to 20.0% Li ₂ O component in% by weight and / or Na ₂ O component from 0 to 35.0% and / or _{K 2} O ingredient 0 20.0%
The optical glass according to any one of (1) to (3), further comprising:

(5) The optical glass according to (4), 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 more than 7.0% and 35.0% or less.

(6) The optical glass according to (5), wherein the mass sum Li ₂ O + Na ₂ O + K ₂ O is more than 10.0% with respect to the total glass mass of the oxide equivalent composition.

(7) The optical glass according to any one of (1) to (6), further containing 20.0% or less of a WO ₃ component in terms of% by mass relative to the total mass of the oxide-converted composition.

(8) the entire mass of the glass in terms of oxide composition, the content of WO ₃ components in mass% is less than 10.0% (7), wherein the optical glass.

(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 30.0% 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) as oxide entire mass of the glass composition, _B 2 _{O 3} component from 0 to 10.0% and / or SiO ₂ component from 0 to 10.0% and / or GeO ₂ component 0-10 mass% 0.0% and / or Bi ₂ O ₃ component 0-20.0% and / or ZrO ₂ component 0-10.0% and / or ZnO component 0-10.0% and / or Al ₂ O ₃ component 0 10.0% and / or Ta ₂ O ₅ component 0 to 10.0% and / or Sb ₂ O ₃ component 0 to 1.0%
The optical glass according to any one of (1) to (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 a wavelength (λ ₇₀ ) having a spectral transmittance of 70% is 500 nm or less.

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

  (17) A precision press-molding preform comprising the optical glass according to any one of (1) to (15).

  (18) An optical element obtained by precision press-molding the precision press-molding preform according to (17).

According to the present _invention, by a combination of P 2 _{O 5} component and _Nb 2 _{O 5 component,} suppresses P 2 _{O 5} component, the content of _Nb 2 _{O 5} component and TiO ₂ component within a predetermined range, the glass Although the refractive index is increased, the dispersion is increased to obtain a low Abbe number, the transparency of the glass to visible light is increased, and the glass transition point (Tg) is lowered. Therefore, an optical glass having a low Abbe number (ν _d ) while having a refractive index (n _d ) within a desired range, high transparency to visible light, and being easily softened at a low temperature, and The optical element used and the precision press molding preform can be provided.

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. It contains 60.0% or less, the content of TiO ₂ component is less than 10.0%, and has a glass transition point (Tg) of 700 ° C. or less. By using the P ₂ O ₅ component and the Nb ₂ O ₅ component together, and suppressing the contents of the P ₂ O ₅ component, the Nb ₂ O ₅ component, and the TiO ₂ component within a predetermined range, it is possible to increase the refractive index of the glass. Although being achieved, the dispersion is increased to obtain a low Abbe number, the transparency of the glass to visible light is increased, and the glass transition point (Tg) is lowered. Therefore, an optical element having a low Abbe number (ν _d ) while having a refractive index (n _d ) within a desired range, high transparency to visible light, and being easy to soften and press-mold at a low temperature. Glass, an optical element using the glass, and a precision press-molding preform can be provided.

  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%. The upper limit is 0.0%, more preferably 35.0%, and most preferably 30.0%. 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, the stability of the glass can be increased and the devitrification resistance can be increased. Therefore, the content of the Nb ₂ O ₅ component with respect to the total glass mass of the oxide conversion composition is preferably 10.0%, more preferably 20.0%, and most preferably 30.0%, and preferably 60%. The upper limit is 0.0%, more preferably 58.0%, and most preferably 55.0%. The Nb ₂ O ₅ component can be contained in the glass using, for example, Nb ₂ O ₅ as a raw material.

TiO ₂ component increases the refractive index and dispersion of the glass, or to enhance the chemical durability of the glass, an optional component of the optical glass of the present invention. In particular, by making the content of the TiO ₂ component less than 10.0%, while obtaining a high refractive index and dispersion, the transparency of the glass with respect to visible light is enhanced, the stability of the glass is enhanced, and devitrification resistance is increased. Can be increased. Accordingly, the content of the TiO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably less than 10.0%, more preferably 9.8%, and most preferably 9.5%. In order to obtain a highly transparent glass with respect to visible light, it may be less than 5.0%. Although TiO ₂ component can be obtained an optical glass having a desired high dispersion and high transmittance even without containing, by containing a TiO ₂ component than 0.1%, acid resistance of the glass is enhanced Therefore, discoloration during processing of the glass can be reduced. Therefore, in this case, the content of the TiO ₂ component with respect to the total amount of glass in the oxide-converted composition is preferably 0.1%, more preferably 1.0%, and most preferably 2.0%. 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 and improves the devitrification resistance of glass, and is an arbitrary component in the optical glass of this invention. In particular, by setting the content of the BaO component to 20.0% or less, it is possible to easily obtain a desired high refractive index, and to suppress a decrease in devitrification resistance and chemical durability. Therefore, the content of the BaO component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 19.0%, and most preferably 18.0%. 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-converted composition is preferably less than 17.0%, more preferably 15. Less than 0%, most preferably less than 13.0%. Although it is possible to obtain an optical glass having a desired high dispersion and high transmittance without containing a BaO component, the liquidus temperature of the glass can be increased by containing more than 1.0% of the BaO component. Since it becomes low, the glass which has high devitrification resistance and is easy to produce stably can be obtained. Therefore, the content of the BaO component with respect to the total glass mass of the oxide-converted composition in this case is preferably 1.0%, more preferably 3.0%, and most preferably 4.5%. 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 Li ₂ O component is a component that lowers the glass transition point (Tg) and increases devitrification resistance during glass formation, and is an optional component in the optical glass of the present invention. In particular, by setting the content of Li 2 _O component below 20.0%, it is possible to easily obtain the desired high refractive index, it is possible to reduce the occurrence of such devitrification increases the stability of the glass. Therefore, the content of the Li ₂ O 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 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 glass transition point (Tg) and increases devitrification resistance during 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 35.0% or less, it is possible to easily obtain a desired high refractive index, and it is possible to increase the stability of the glass and reduce the occurrence of devitrification and the like. Therefore, the content of the Na ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 35.0%, more preferably 25.0%, 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.

The K ₂ O component is a component that lowers the glass transition point (Tg) and increases devitrification resistance during glass formation, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the K ₂ O component to 20.0% or less, it is possible to easily obtain a desired high refractive index, and it is possible to increase the stability of the glass and reduce the occurrence of devitrification and the like. Therefore, the content of the K ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. 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.

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 more than 7.0% and more than 35.0. % Or less is preferable. In particular, when the mass sum of the content ratio of the Rn ₂ O component is more than 7.0%, the glass transition point (Tg) can be lowered and the water resistance of the glass can be increased while achieving high dispersion of the glass. On the other hand, by the mass sum of the content of Rn 2 _O component is less than 35.0%, since the decrease in the refractive index of the glass is suppressed, it is possible to easily obtain the desired high refractive index. Moreover, since the stability of the glass is enhanced, the occurrence of devitrification or the like to the glass can be reduced. Therefore, the mass sum of the content ratio of the Rn ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably more than 7.0%, more preferably 9.0%, and most preferably 10.0%. And Further, the upper limit of this mass sum is preferably 35.0%, more preferably 32.0%, and most preferably 30.0%.

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, the glass transition point (Tg) can be lowered, and a decrease in the transmittance of the glass with respect to visible light having a short wavelength can be suppressed. Therefore, 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 17.0%, and most preferably 15.0%. In particular, the content of the WO ₃ component is preferably 10.0% or less from the viewpoint that a glass having a desired high dispersion and a low glass transition point (Tg) can be easily obtained. Accordingly, in this case, the content of the WO ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 10.0%, more preferably 7.0%, and most preferably 5.0%. The WO ₃ component can be contained in the glass using, for example, WO ₃ as a raw material.

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-converted composition is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. 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 30.0% 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 30.0%, more preferably 27.0%, and most preferably 25.0%. An optical glass having a desired high dispersion and high transmittance can be obtained without containing any RO component. However, by containing at least one of the RO 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, in this case, the mass sum of the content ratio of the RO component with respect to the total glass substance amount of the oxide conversion composition is preferably 0.1%, more preferably 1.0%, and most preferably 3.0%. 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-converted composition is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. Although B ₂ O ₃ component can be obtained an optical glass having a desired high dispersion and high transmittance even without containing, by containing B ₂ O ₃ component of 0.1% or more, the liquid glass Since the phase temperature is increased, the devitrification resistance of the glass can be further increased. Accordingly, in this case, the content of the B ₂ O ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 0.1%, more preferably 0.3%, and most preferably 0.5%. 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 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. Therefore, the content of the SiO 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%. 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 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 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 15.0 mol% and / or BaO component 0 to 30.0 mol% and / or Li ₂ O component 0 to 50.0 mol% and / or Na ₂ O component 0 to 50.0 mol% and / or K ₂ O component 0 to 30.0 mol% and / or WO ₃ component 0 to 15.0 mol% and / or MgO component 0 to 20.0 mol% and / or CaO component 0 to 25.0 mol% 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 SiO ₂ component 0～20.0Mol% and / or GeO ₂ component 0～15.0Mol% and / or _Bi 2 _{O 3} component 0 4.0 mol% and / or ZrO ₂ component 0～13.0Mol% 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 _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 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 1.80, and most preferably with a lower limit on 1.85, preferably 2.20, more preferably 2. 15, most preferably 2.10. Further, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 25, more preferably 22, most preferably 20. 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, the optical glass of the present invention has a glass transition point (Tg) of 700 ° C. or lower. Thereby, since glass softens at lower temperature, glass can be press-molded at lower temperature. In addition, it is possible to extend the life of the mold by reducing oxidation of the mold used for precision press molding. Therefore, the upper limit of the glass transition point (Tg) of the optical glass of the present invention is preferably 700 ° C., more preferably 670 ° C., and most preferably 650 ° C. The lower limit of the glass transition point (Tg) of the optical glass of the present invention is not particularly limited, but the glass transition point (Tg) of the glass obtained by the present invention is generally 100 ° C. or higher, specifically 150 ° C. or higher. More specifically, it is often 200 ° C. or higher.

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.

[Preforms and optical elements]
The optical glass of the present invention is useful for various optical elements and optical designs. Among them, optical elements such as lenses, prisms, mirrors and the like are used by using means such as precision press molding from the optical glass of the present invention. It is preferable to produce it. 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. Here, in order to produce an optical element made of the optical glass of the present invention, it is possible to omit cutting and polishing, so that glass in a molten state is dropped from an outlet of an outflow pipe of platinum or the like to form a spherical shape. It is preferable to prepare a precision press-molding preform such as, and perform precision press-molding on the precision press-molding preform.

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. 5) and Comparative Example (No. 1) of the present invention are 70%. Table 1 shows (λ ₇₀ ) and the glass transition point (Tg). The following examples are merely for illustrative purposes, and are not limited to these examples.

  The optical glass of Examples (No. 1 to No. 5) 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, and metaphosphate compounds, and weigh them to the proportions of the examples and comparative examples shown in Table 1. 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, regarding the refractive index (n _d ) and Abbe number (ν _d ) of the glass of Examples (No. 1 to No. 5) and Comparative Example (No. 1), 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, about the transmittance | permeability of the glass of an Example (No.1-No.5) 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 glass transition point (Tg) of the optical glass of an Example (No.1-No.5) and the glass of a comparative example (No.1) was calculated | required by performing the measurement using a horizontal expansion measuring device. Here, the sample used for the measurement was φ4.5 mm and a length of 5 mm, and the heating rate was 4 ° C./min.

  As shown in Table 1, all of the optical glasses of the examples of the present invention had a glass transition point (Tg) of 700 ° C. or lower, more specifically 650 ° C. or lower. On the other hand, the glass of the comparative example had a glass transition point (Tg) higher than 650 ° C. For this reason, it became clear that the optical glass of the Example of this invention has a low glass transition point (Tg) compared with the glass of a comparative example, and it is easy to soften with low heating temperature.

The optical glasses of the examples of the present invention all have a refractive index (n _d ) of 1.70 or more, more specifically 1.86 or more, and this refractive index (n _d ) is 2.20 or less. More specifically, it was 2.00 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 the Abbe number (ν _d ) of 25 or less, more specifically 24. And within the desired range.

In addition, in all the optical glasses of the examples of the present invention, λ ₇₀ (wavelength at 70% transmittance) was 500 nm or less, more specifically 450 nm or less, and was in a desired range.

Therefore, the optical glass of the embodiment of the present invention has a low Abbe number (ν _d ) while having a refractive index (n _d ) within a desired range, has high transparency to visible light, and has a low temperature. It has become clear to provide optical glass, optical elements and precision press molding preforms that are easy to soften.

  Furthermore, when a precision press-molding preform was formed using the optical glass of the embodiment of the present invention, and the precision press-molding preform was precision press-molded, it could be stably processed into various lens 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 (18)

The entire mass of the glass 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 a content of TiO ₂ component is less than 10.0%, the optical glass having 700 ° C. or less of the glass transition point (Tg). BaO component 0 to 30.0% in mass% with respect to the total mass of the glass in oxide equivalent composition
The optical glass according to claim 1, further comprising:   The optical glass according to claim 2, wherein the content of the BaO component is 1.0% or more and less than 17.0% by mass% with respect to the total mass of the glass having an oxide equivalent composition. Li ₂ O component 0 to 20.0% and / or Na ₂ O component 0 to 35.0% and / or K ₂ O component 0 to 20.0% by mass with respect to the total glass mass of the oxide equivalent composition. %
The optical glass according to claim 1, further comprising: 5. The optical glass according to claim 4, 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 more than 7.0% and 35.0% or less. The optical glass according to claim 5, wherein the mass sum Li ₂ O + Na ₂ O + K ₂ O is more than 10.0% with respect to the total glass mass of the oxide equivalent composition. The optical glass according to any one of claims 1 to 6, further containing 20.0% or less of a WO ₃ component in terms of% by mass relative to the total mass of the glass having an oxide equivalent composition. The optical glass according to claim 7, wherein the content of the WO ₃ component is 10.0% or less by mass with respect to the total glass mass of the oxide equivalent composition. 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 30.0% 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 SiO ₂ component 0 to 10.0% and / or GeO ₂ component 0 to 10.0% by mass% with respect to the total glass mass of the oxide conversion composition And / or Bi ₂ O ₃ component 0 to 20.0% and / or ZrO ₂ component 0 to 10.0% and / or ZnO component 0 to 10.0% and / or Al ₂ O ₃ component 0 to 10.0 % and / or _Ta 2 _{O 5} component from 0 to 10.0% and / or _Sb 2 _{O 3} component from 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 (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 a wavelength (λ ₇₀ ) at which the spectral transmittance is 70% is 500 nm or less.   An optical element made of the optical glass according to claim 1.   A precision press-molding preform comprising the optical glass according to claim 1.   An optical element formed by precision press-molding the precision press-molding preform according to claim 17.