JP5543078B2 - Optical glass and optical element - Google Patents

Description

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

  In recent years, digital devices and high-definition optical devices have progressed, and optical elements such as various lenses are used in image reproduction (projection) devices such as projectors and projection televisions, as well as photographing devices such as digital cameras and video cameras. In these, high performance is required.

Among optical glasses for producing such optical elements, the demand for high refractive index and high dispersion glass is greatly increased. Among the high refractive index and high dispersion glass, for example, as an optical glass having a refractive index (n _d ) of 1.7 or more and an Abbe number (ν _d ) of 20 or more and 30 or less, as represented by Patent Documents 1 to 3 Glass compositions are known.
JP 2004-15563 A Chinese Patent No. 1915875 Specification JP 2002-249336 A

  The performance of optical glass for producing optical elements includes not only the optical properties required for optical glass such as the above-mentioned refractive index, Abbe number and coloring degree, but also optical elements using optical glass. It is important that the processing performance at the time of processing is good and that the environmental load is small when manufacturing optical glass or processing optical elements.

  Among these, chemical durability is mentioned as an example of the processing performance at the time of manufacturing an optical element etc. using optical glass, for example. When an optical element or the like is manufactured using optical glass having low chemical durability such as water resistance and acid resistance, the optical glass is likely to be burned by water or acid used in the manufacturing process.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical glass and an optical glass having high chemical durability while having a refractive index and an Abbe number within desired ranges. It is to provide an element.

In order to solve the above-mentioned problems, the present inventors have conducted intensive test studies, and as a result, the Nb ₂ O ₅ component, the TiO ₂ component, and the SiO ₂ component are contained in a predetermined content, and the alkali metal component and It has been found that by making the balance with the alkaline earth metal component a predetermined condition, the high refractive index and chemical durability of the glass can both be achieved, and the present invention has been completed. Specifically, the present invention provides the following.

(1) 27.0 to 46.0% of SiO ₂ component, 20.0 to 35.0% of TiO ₂ component, and Nb ₂ O ₅ component in mass% with respect to the total glass mass of oxide conversion composition. 1.0-15.0%, RO component 2.0-25.0% (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba), and Rn ₂ O component In an optical glass containing 3.0 to 30.0% (wherein Rn is one or more selected from the group consisting of Li, Na, K, and Cs).

(2) The optical glass according to (1), wherein the mass% ratio (K ₂ O) / (Na ₂ O) is 0.35 or more and 0.80 or less.

(3) CaO 0 to 15.0% and / or SrO 0 to 15.0% in mass% with respect to the total glass mass of the oxide equivalent composition.
The optical glass according to (1) or (2), further containing each component of

(4) The optical glass according to any one of (1) to (3), wherein a mass% ratio (Na ₂ O + K ₂ O) / (BaO + SrO + CaO) is 0.80 or more and 2.50 or less.

(5) MgO 0 to 5.0% and / or Li ₂ O 0 to 5.0% and / or ZrO ₂ 0 to 9.0% and / or by mass% with respect to the total glass mass of the oxide equivalent composition. or _Sb 2 _O 3 _0~1.0% and / or _B 2 _O 3 _0~3.0% and / or _Al 2 _O 3 _0~4.0% and / or _Ln 2 _O 3 _0~10.0% (Ln is one or more selected from the group consisting of Y, La, Gd, and Lu) and / or ZnO 0 to 5.0% and / or Ta ₂ O _{5 0 to} 10.0% and / or WO ₃ 0 to 10.0%
The optical glass according to any one of (1) to (4), further comprising:

(6) The optical glass according to any one of (1) to (5), having a refractive index (n _d ) of 1.7 or more and an Abbe number (ν _d ) of 20 or more and 30 or less.

  (7) The chemical durability (water resistance) by the powder method is class 2 or 1, and the chemical durability (acid resistance) by the powder method is class 2 or 1 (1) to (6) Optical glass as described in any one of.

  (8) An optical element such as a lens or a prism using the optical glass according to any one of (1) to (7) as a base material.

  (9) An optical element such as a lens or a prism produced by reheat press processing the optical glass according to any one of (1) to (7).

  (10) An optical device such as a camera or a projector, comprising an optical element made of the optical glass according to any one of (1) to (7) and an optical substrate material.

According to the present invention, the refractive index of glass is increased by containing Nb ₂ O ₅ component and TiO ₂ component as essential components in a predetermined content range, and the chemical durability of the glass is enhanced by the SiO ₂ component. The Abbe number of the glass is adjusted by the alkali metal component and the alkaline earth metal component. Therefore, it is possible to provide an optical glass and an optical element having desired chemical durability while the refractive index and the Abbe number are within a desired range.

  Next, the reason why the composition range of each component is limited as described above in the optical glass of the present invention will be described. In the present specification, unless otherwise specified, the content of each component is expressed in mass%.

[Glass component]
In the optical glass of the present invention, the SiO ₂ component is 27.0 to 46.0%, the TiO ₂ component is 20.0 to 35.0%, and Nb _{2 in} mass% with respect to the total glass mass of the oxide equivalent composition. O ₅ component 1.0-15.0%, RO component 2.0-25.0% (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba), and Rn ₂ O component is contained in an amount of 3.0 to 30.0% (wherein Rn is one or more selected from the group consisting of Li, Na, K, and Cs). By adding the Nb ₂ O ₅ component and the TiO ₂ component as essential components within the above range of the content, the refractive index of the glass can be increased without using a lead compound. Further, the addition within the scope of the content of the SiO ₂ component as an essential component, the chemical durability of the glass is increased. Furthermore, the addition within the scope of the content of alkali metal components (Rn 2 _O component) and alkaline earth metal components (RO component) as essential components, the Abbe number and the like of the glass is adjusted. For this reason, the chemical durability of the optical glass can be further increased while the refractive index (n _d ) is increased to 1.7 or more and the Abbe number (ν _d ) is in the range of 20 to 30.

<About essential and optional components>
The SiO ₂ component is a component that promotes stable glass formation and reduces devitrification (generation of crystalline substances), which is undesirable as an optical glass. In particular, when the content of the SiO ₂ component is 27.0% or more, desired chemical durability of the glass can be achieved. Further, by setting the content of SiO ₂ component below 46.0%, it is possible to obtain a desired refractive index can be kept good meltability of the glass. Accordingly, the content of the SiO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably 27.0%, more preferably 27.2%, most preferably 27.4%, and preferably 46.0%. %, More preferably 45.0%, and most preferably 44.5%. SiO ₂ component may be contained in the glass by using as a raw material such as _{SiO 2, K 2 SiF 6,} Na 2 SiF 6 or the like.

The TiO ₂ component is a component that increases the refractive index and the chemical durability (acid resistance). In particular, when the content of the TiO ₂ component is 20.0% or more, the desired refractive index, Abbe number, and the like of the glass can be achieved. Further, by making the content of the TiO ₂ component 35.0% or less, the coloration of the glass can be reduced, and in particular, the light transmittance of a visible short wavelength (500 nm or less) can be made difficult to deteriorate. . Accordingly, the content of the TiO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 21.0%, most preferably 22.0%, and preferably 35.0%. %, More preferably 33.0%, and most preferably 32.0%. TiO ₂ component may be contained in the glass by using as the starting material for example TiO ₂ or the like.

The Nb ₂ O ₅ component is a component that increases the refractive index and stabilizes the glass. In particular, when the content of the Nb ₂ O ₅ component is 1.0% or more, desired glass characteristics can be achieved. Further, by setting the content of Nb ₂ O ₅ component below 15.0%, it is possible to easily adjust the Abbe number of the glass to a desired value. At the same time, since the increase in melting temperature during glass production is suppressed, production costs can be reduced. Therefore, the content of the Nb ₂ O ₅ component with respect to the total glass mass of the oxide conversion composition is preferably 1.0%, more preferably 1.3%, and most preferably 1.5%, and preferably 15%. 0.0%, more preferably 13.0%, and most preferably 12.0%. The Nb ₂ O ₅ component can be contained in the glass using, for example, Nb ₂ O ₅ as a raw material.

The RO (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is a component that adjusts the refractive index and photoelastic constant of the glass. In particular, when the content of the RO component is 2.0% or more, desired glass characteristics can be achieved. Moreover, a desired refractive index can be obtained by making the content rate of RO component 25.0% or less. Accordingly, the total content of the RO component with respect to the total glass mass of the oxide conversion composition is preferably 2.0%, more preferably 5.0%, and most preferably 7.0%, and preferably 25. The upper limit is 0%, more preferably 20.0%, and most preferably 16.0%. These RO components are carbonate (MgCO ₃ , CaCO ₃ , BaCO ₃ ), nitrate (Sr (NO ₃ ) ₂ , Ba (NO ₃ ) ₂ ), fluoride (MgF ₂ , CaF ₂ , SrF ₂ , BaF ₂ ). Etc. can be used in the glass, but it is preferably contained in the glass in the form of carbonate and / or nitrate and / or fluoride.

  Among these, the MgO component is a component that maintains the optical constant 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, the glass can be stabilized and the generation of crystals during cooling can be reduced. Therefore, 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%.

  Moreover, a CaO component is a component which reduces the Abbe number of glass, and is an arbitrary component in the optical glass of this invention. In particular, the refractive index of glass can be made hard to fall by making the content rate of a CaO component 15.0% or less. Therefore, the content of the CaO component with respect to the total glass mass of the oxide conversion composition is preferably 15.0%, more preferably 10.0%, and most preferably 5.0%.

  Moreover, a SrO component is a component which raises the refractive index of glass, and is an arbitrary component in the optical glass of this invention. In particular, by setting the content of the SrO component to 15.0% or less, a desired optical constant can be easily realized. Therefore, the content of the SrO component with respect to the total glass mass of the oxide conversion composition is preferably 15.0%, more preferably 10.0%, and most preferably 5.0%.

  Moreover, a BaO component is a component which raises the refractive index of glass and is an arbitrary component in the optical glass of this invention. In particular, when the content of the BaO component is 25.0% or less, a desired optical constant can be easily realized. Therefore, the content of the BaO component with respect to the total glass mass of the oxide-converted composition is preferably 25.0%, more preferably 20.0%, and most preferably 15.0%.

Rn ₂ O (wherein Rn is one or more selected from the group consisting of Li, Na, K, and Cs) is a component that improves the meltability of glass. In particular, when the content of the Rn ₂ O component is 3.0% or more, desired glass characteristics can be achieved. Further, by setting the content of Rn 2 _O components below 30.0%, it is possible to obtain a desired refractive index can be difficult to generate the devitrification to the glass. Therefore, the total content of the Rn ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 3.0%, more preferably 5.0%, most preferably 7.0%, and preferably The upper limit is 30.0%, more preferably 25.0%, and most preferably 20.0%. These Rn ₂ O components are carbonates (Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Cs ₂ CO ₃ ), nitrates (LiNO ₃ , NaNO ₃ , KNO ₃ , CsNO ₃ ), fluorides (LiF , NaF, KF, KHF ₂ ), composite salts (Na ₂ SiF ₆ , K ₂ SiF ₆ ), etc., can be contained in the glass, but are contained in the glass in the form of carbonate and / or nitrate. It is preferable.

Among, Li 2 _O component is a component for improving the meltability of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of the Li ₂ O component to 5.0% or less, it is easy to realize a high refractive index, and it is possible to reduce milking and crystal precipitation in the glass reheating (reheating) step. . Therefore, the content of the Li ₂ O 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%.

Further, Na 2 _O component is a component for improving the meltability of the glass, an optional component of the optical glass of the present invention. In particular, by making the content of the Na ₂ O component 18.0% or less, a desired Abbe number can be realized even if the refractive index of the glass is high, and chemical durability is hardly deteriorated. Can do. Accordingly, the content of the Na ₂ O component with respect to the total glass mass of the oxide-converted composition is preferably 18.0%, more preferably 15.0%, and most preferably 12.0%. In the present invention, an optical glass having desired physical properties can be produced even if it does not contain a Na ₂ O component. However, in order to facilitate the above effects, it is preferably 2.0%, more preferably 4. The lower limit is 0%, and most preferably 6.0%.

Further, K 2 _O component is a component that adjusts the refractive index and Abbe number while adjusting melting property of the glass is any component of the optical glass of the invention. In particular, by setting the content of the K ₂ O component to 10.0% or less, a desired Abbe number can be realized even if the refractive index of the glass is high. Therefore, the content of the K ₂ O component with respect to the total glass mass of the oxide-converted composition is preferably 10.0%, more preferably 8.0%, and most preferably 7.0%. In the present invention, an optical glass having desired physical properties can be produced without containing a K ₂ O component. However, in order to facilitate the above effect, it is preferably 1.0%, more preferably 2. The lower limit is 0%, and most preferably 3.0%.

In the optical glass of the present invention, the mass% ratio of the Na ₂ O component content to the K ₂ O component content is preferably 0.35 or more and 0.80 or less. By making this mass% ratio 0.35 or more, the chemical durability of the optical glass can be enhanced while maintaining desired optical characteristics. Moreover, it can be made hard to generate | occur | produce the devitrification to glass by making this mass% ratio 0.80 or less. Accordingly, the mass% ratio of the Na ₂ O content to the K ₂ O content is preferably 0.35, more preferably 0.38, most preferably 0.39, and preferably 0.80. More preferably, the upper limit is 0.70, and most preferably 0.60.

Further, in the optical glass of the present invention, the ratio of the mass sum of the content ratios of Na ₂ O and K ₂ O to the mass sum of the content ratios of each component of BaO, SrO, and CaO is 0.94 or more. 2.50 or less is preferable. These components are all components that improve the refractive index of the glass, but the mass of the content of each component of Na ₂ O and K ₂ O with respect to the mass sum of the content of each component of BaO, SrO, and CaO. By making the sum ratio 0.80 or more, the meltability of the glass can be enhanced. Further, by setting the ratio of these mass sums to 2.50 or less, it is possible to strengthen the bonding of the glass and improve the chemical durability. Therefore, the ratio of the mass sum of the content of each component of Na ₂ O and K ₂ O to the mass sum of the content of each component of BaO, SrO, and CaO is preferably 0.80, more preferably 0.8. 82, most preferably 0.83 is the lower limit, preferably 2.50, more preferably 2.30, and most preferably 2.10.

The ZrO ₂ component is a component that increases the refractive index of the glass and suppresses devitrification in the process of cooling the glass from the molten state, and is an optional component in the optical glass of the present invention. In particular, when the content of the ZrO ₂ component is 9.0% or less, the glass is easily melted at a lower temperature, so that energy loss during glass production can be reduced. Therefore, the content of the ZrO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably 9.0%, more preferably 7.0%, and most preferably 5.0%. Even without the addition of the ZrO ₂ component, if the devitrification in the glass does not occur, even without containing no problem. 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 Sb ₂ O ₃ component is a component that promotes defoaming of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the Sb ₂ O ₃ component to 1.0% or less, excessive foaming at the time of melting the glass can be made difficult, and the Sb ₂ O ₃ component can be dissolved in a melting facility (especially a noble metal such as Pt). ) And alloying can be made difficult. Therefore, the content of the Sb ₂ O ₃ component with respect to the total glass mass of the oxide-converted composition is preferably 1.0%, more preferably 0.9%, and most preferably 0.8%. 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.

The B ₂ O ₃ component is a component having an effect of promoting stable glass formation, and is an optional component in the optical glass of the present invention. In particular, by setting the content ratio of the B ₂ O ₃ component to 3.0% or less, a desired refractive index can be obtained, and a decrease in the chemical durability of the glass can be suppressed. Therefore, the content of the B ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 3.0%, more preferably 2.0%, and most preferably 1.0%. The B ₂ O ₃ component can be contained in the glass using, for example, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ · 10H ₂ O, BPO ₄ or the like as a raw material. ₃ BO ₃ is preferably contained in the glass.

The Al ₂ O ₃ component is an effective component for enhancing the chemical durability of the glass and improving the devitrification resistance of the molten glass, and is an optional component in the optical glass of the present invention. Therefore, the content of the Al ₂ O ₃ component with respect to the total glass mass of the oxide-converted composition is preferably 4.0%, more preferably 3.0%, and most preferably 2.0%. 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.

Ln ₂ O ₃ component (Ln is one or more selected from the group consisting of Y, La, Gd, Yb, and Lu) is a component that realizes a high refractive index and improves chemical durability (water resistance) It is. In particular, by making the content of the Ln ₂ O ₃ component 5.0% or less, the chemical durability (acid resistance) is hardly deteriorated, the decrease in dispersion of the glass is suppressed, and the desired optical constant and Chemical durability can be easily obtained. Further, since _Ln 2 _{O 3} component is a rare mineral resource, by the content of _Ln 2 _{O 3} component to 5.0% or less, it is possible to reduce the material cost of the glass. Therefore, the content of the Ln 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%.

A ZnO component is a component which improves the meltability of glass and raises a refractive index, and is an arbitrary component in the optical glass of this invention. In particular, when the ZnO component content is 5.0% or less, the glass is easily stabilized. Accordingly, the content of the ZnO component with respect to the total glass mass of the oxide-converted composition is preferably 5.0%, more preferably 2.0%, and most preferably 1.0%. The ZnO component can be contained in the glass using, for example, ZnO, ZnF ₂ or the like as a raw material.

The Ta ₂ O ₅ component is a component that increases the refractive index of the glass and stabilizes the glass, and is an optional component in the optical glass of the present invention. In particular, by making the content of Ta ₂ O ₅ component 10.0% or less, the amount of Ta ₂ O ₅ component, which is a rare mineral resource, is reduced, and the glass is more easily melted at a lower temperature. The production cost can be reduced. Accordingly, 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 6.0%. The Ta ₂ O ₅ component can be contained in the glass using, for example, Ta ₂ O ₅ as a raw material.

The WO ₃ component is a component that adjusts the refractive index and dispersion of the glass and improves the devitrification resistance of the glass, and is an optional component in the optical glass of the present invention. In particular, by making the content of the WO ₃ component 10.0% or less, the coloration of the glass can be reduced, and the transmittance of the glass in the visible-short wavelength region (less than 500 nm) can be increased. Accordingly, 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 8.0%, and most preferably 6.0%. The WO ₃ component can be contained in the glass using, for example, WO ₃ as a raw material.

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

The GeO ₂ component is a component that adjusts the refractive index of glass and the viscosity of molten glass, but is a rare mineral resource and an expensive component. Accordingly, the content of the GeO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably 0.1% as an upper limit, and more preferably not contained.

Each component in the Ga ₂ O ₃ and the Bi ₂ O ₃ is a component that adjusts the refractive index of the glass, the material cost since it is a rare mineral resources causes to rise. Accordingly, the content of these components with respect to the total glass mass of the oxide conversion composition is preferably 1.0%, more preferably 0.5%, and most preferably not contained.

The P ₂ O ₅ component is a component that improves the meltability of the glass, but has a property that the devitrification resistance of the glass is likely to deteriorate and it becomes difficult to obtain an optical glass without devitrification. Therefore, the content of the P ₂ O ₅ component with respect to the total glass mass of the oxide-converted composition is preferably 5.0%, more preferably 1.0%, and most preferably not contained.

The TeO ₂ component is a component that promotes the clarification action when the glass is melted, but has a property that the coloration of the glass becomes remarkable and the transmittance tends to deteriorate. Therefore, the content of the TeO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably 3.0%, more preferably 1.5%, and most preferably not contained.

  Each transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag and Mo, excluding Ti, is colored by the glass even when contained in a small amount by combining them individually or in combination. In particular, in the optical glass using a wavelength in the visible region, it is preferable that it is not substantially contained.

Furthermore, lead compounds such as PbO, arsenic compounds such as As ₂ O ₃ , and components of Th, Cd, Tl, Os, Be, and Se tend to be refrained from being used as harmful chemical substances in recent years and are unavoidable. It is preferable not to contain these except for contamination. As a result, the optical glass is substantially free of substances that pollute the environment. Therefore, the optical glass can be manufactured, processed, and discarded without taking any special environmental measures.

  In the present specification, the “oxide equivalent composition” is assumed that oxides, composite salts, metal fluorides, etc. used as a raw material of the glass component of the present invention are all decomposed and changed to oxides when melted. In this case, the total mass of the generated oxide is 100% by mass, and each component contained in the glass is described.

Moreover, since the composition of the glass composition of the present invention is expressed by mass%, it cannot be expressed directly in the description of mol%, but in the glass composition satisfying various characteristics required in the present invention. The composition represented by mol% of each component present generally takes the following values in terms of oxide equivalent composition.
SiO ₂ component 36-55 mol%,
TiO ₂ component 20-35 mol%,
Nb ₂ O ₅ component 0.5 to 5.0 mol%,
RO component 2~20mol%, and Rn ₂ O components 3 to 30 mol%,
And CaO components 0 to 20 mol% and / or SrO component 0～15Mol% and / or ZrO ₂ component 0～6Mol% and / or _Sb 2 _{O 3} component 0～0.3Mol% and / or _B 2 _{O 3} component 0 4 mol% and / or _Al 2 _{O 3} component 0～3Mol% and / or _Ln 2 _{O 3} component 0~3mol% (Ln is Y, La, Gd, and one or more selected from the group consisting of Lu) and / or MgO component 0-10 mol% and / or ZnO component 0 to 5 mol% and / or Li ₂ O component 0-10 mol% and / or _Ta 2 _{O 5} component 0～3Mol% and / or WO ₃ components 0 to 5 mol%

[Production method]
The optical glass of the present invention is produced, for example, as follows. That is, the above raw materials are mixed so that each component is within a predetermined content range, and the prepared mixture is put in a container made of platinum, a platinum alloy, or quartz, and a temperature range of 1200 to 1400 ° C. is 3 to 10 ° C. After melting for a period of time, stirring and homogenizing to blow out bubbles, the temperature is lowered to an appropriate temperature, cast into a mold, and slowly cooled.

[Physical properties]
The optical glass of the present invention must have a refractive index (n _d ) as high as possible and have appropriate dispersibility. In particular, it preferably has a refractive index (n _d ) of 1.7 or more and an Abbe number (ν _d ) of 20 or more and 30 or less. Thereby, even if the device is made thin, a large amount of light refraction can be obtained and desired chromatic aberration can be obtained.

  Further, the optical glass of the present invention needs to have as high chemical durability as possible. In particular, the chemical durability (water resistance) of the glass according to JOGIS06-1999 is class 2 or 1, and the chemical durability (acid resistance) of the powder method is class 2 or 1. It is preferable. Thereby, when processing an optical glass and manufacturing an optical element, the burning of the glass by water and an acid is reduced, Therefore The optical element which has a desired optical characteristic can be manufactured more reliably.

  Here, “chemical durability” means durability against the erosion of glass by water or acid. The durability against water and the acid resistance against acid are determined by the Japan Optical Glass Industry Association Standard “Chemical durability of optical glass”. Measurement method "can be measured according to JOGIS06-1999. “The chemical durability (water resistance) by the powder method is class 2 or 1” means that the chemical durability (water resistance) performed according to JOGIS06-1999 is the mass of the sample before and after the measurement. It means that it is less than 0.10% by mass. In Class 1, the weight loss rate of the sample before and after the measurement is less than 0.05% by mass, and in Class 2, it is 0.05% by mass or more and less than 0.10% by mass. “The chemical durability (acid resistance) by the powder method is class 2 or 1” 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 that it is less than 0.35 mass%. In Class 1, the weight loss rate of the sample before and after measurement is less than 0.20% by mass, and in Class 2, it is 0.20% by mass or more and less than 0.35% by mass.

[Optical elements and optical equipment]
Therefore, although the optical glass of the present invention is useful for various optical elements and optical designs, it is particularly preferable to produce an optical element such as a lens or a prism using the optical glass of the present invention as a base material. As a result, when used in an optical apparatus such as a camera or a projector, it is possible to reduce the size of the optical system in these optical apparatuses while realizing high-definition and high-precision imaging and projection characteristics. Here, in order to produce an optical element such as a lens or a prism from the optical glass of the present invention, it is preferable to use reheat press processing because most of the cutting can be omitted.

Composition of Examples (No. 1 to No. 13) of the present invention, and refractive index (n _d ), Abbe number (ν _d ), and chemical durability (water resistance and acid resistance) of these glasses The results are shown in Tables 1 and 2. Among these, Examples (No. 1, 4, 6, 9, 11 to 13) are reference examples of the present invention. The following examples are merely for illustrative purposes, and are not limited to these examples.

  The optical glasses of the examples (No. 1 to No. 13) of the present invention are all oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, metaphosphoric acids corresponding to the raw materials of the respective components. Select high-purity raw materials used for ordinary optical glass such as compounds, weigh and mix so as to have the composition ratio of each example shown in Table 1 and Table 2, and then put into a platinum crucible, Depending on the melting difficulty of the glass composition, melt in an electric furnace at a temperature range of 1200 to 1400 ° C. for 3 to 4 hours, stir and homogenize, lower to an appropriate temperature, cast into a mold, etc., and slowly cool It was obtained.

Here, the refractive index (n _d ) and the Abbe number (ν _d ) of the optical glass of the examples (No. 1 to No. 13) are obtained with respect to the glass obtained by setting the slow cooling / cooling rate to −25 ° C./h. It was determined by measuring.

  The water resistance was measured in accordance with Japan Optical Glass Industry Association Standard “Method for Measuring Chemical Durability of Optical Glass” JOGIS06-1999. 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 pure water (pH 6.5-7.5) and treated in a boiling water bath for 60 minutes. The weight loss rate (mass%) of the glass sample after the treatment is calculated, class 1 when this weight loss rate is less than 0.05, class 2 when the weight loss rate is less than 0.05 to 0.10, and weight loss rate. Is less than 0.10 to 0.25 class 3, when the weight loss rate is less than 0.25 to 0.60, class 4 and when the weight loss rate is less than 0.60 to 1.10, class 5. The case where the rate was 1.10 or higher was classified as class 6. At this time, the smaller the number of classes, the better the water resistance of the glass.

  The acid resistance was measured in accordance with the Japan Optical Glass Industry Association Standard “Method for Measuring Chemical Durability of Optical Glass” JOGIS06-1999. 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 treated glass sample, class 1 if this weight loss rate (mass%) is less than 0.20, class if the weight loss rate is less than 0.20 to 0.36 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 Tables 1 and 2, all of the optical glasses of Examples (No. 1 to No. 13) of the present invention have a refractive index of 1.7 or more and an Abbe number (ν _d ). It was within the range of 20 or more and 30 or less. In addition, the optical glasses of Examples (No. 1 to No. 13) of the present invention all have chemical durability (water resistance) of class 2 or 1 by the powder method, and chemical durability by the powder method. The property (acid resistance) was class 2 or 1.

  Further, when the optical glass of Examples (No. 1 to No. 13) of the present invention was cold-worked or reheat-pressed, problems such as devitrification did not occur, and it was stably processed into various lenses and prism shapes. We were able to.

  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 (4)

The SiO ₂ component is 38.66 to 46.0% by mass% with respect to the total mass of the glass in oxide conversion composition,
20.0 to 33.0% of TiO ₂ component,
1.0 to 12.0% of Nb ₂ O ₅ component,
4.19-8.82% of BaO component,
2.0 to 12.0% Na ₂ O component,
1.0 to 7.0% of K ₂ O component,
The RO component is 5.0 to 16.0% (wherein R is one or more selected from the group consisting of Mg, Ca, Sr and Ba) and the Rn ₂ O component is 7.0 to 15.09% ( In the formula, Rn contains one or more selected from the group consisting of Li, Na and K) ,
C aO 0 to 10.0%
SrO 0 to 10.0%
MgO 0-5.0%
Li ₂ O 0~5.0%
ZrO ₂ 0-9.0%
Sb ₂ O ₃ 0-1.0%
B ₂ O ₃ 0-3.0%
Al ₂ O ₃ 0-4.0%
Ln ₂ O ₃ 0 to 5.0% (Ln is one or more selected from the group consisting of Y, La, Gd, and Lu)
ZnO 0-5.0%
Ta ₂ O ₅ 0~ 6.0% and _WO 3 0 to 6.0%
And
The mass% ratio (K ₂ O) / (Na ₂ O) is 0.35 or more and 0.80 or less,
The mass% ratio (Na ₂ O + K ₂ O) / (BaO + SrO + CaO) is 0.80 or more and 2.50 or less,
Having an index of refraction (n _d ) of 1.7 or more, an Abbe number (ν _d ) of 20 or more and 30 or less,
Optical glass whose chemical durability (water resistance) by the powder method is class 2 or 1, and whose chemical durability (acid resistance) by the powder method is class 2 or 1. The optical element of the lens or prism to an optical glass of claim 1 Symbol placing the base material. The optical element of the lens or prism to produce an optical glass of claim 1 Symbol placement reheat pressing to. Comprising an optical element and an optical substrate material created in claim 1 Symbol placement of the optical glass, a camera or projector optics of.