JP6014301B2 - Optical glass, preform and optical element - Google Patents

Description

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

  Optical systems such as digital cameras and video cameras, although large and small, contain blurs called aberrations. This aberration is classified into monochromatic aberration and chromatic aberration. In particular, the chromatic aberration is strongly dependent on the material characteristics of the lens used in the optical system.

  In general, chromatic aberration is corrected by combining a low-dispersion convex lens and a high-dispersion concave lens. However, this combination can only correct aberrations in the red region and the green region, and remains in the blue region. This blue region aberration that cannot be removed is called a secondary spectrum. In order to correct the secondary spectrum, it is necessary to perform an optical design in consideration of the trend of the g-line (435.835 nm) in the blue region. At this time, the partial dispersion ratio (θg, F) is used as an index of the optical characteristics to be noticed in the optical design. In the optical system combining the low dispersion lens and the high dispersion lens, an optical material having a large partial dispersion ratio (θg, F) is used for the low dispersion side lens, and the partial dispersion ratio ( By using an optical material having a small θg, F), the secondary spectrum is corrected well.

The partial dispersion ratio (θg, F) is expressed by the following equation (1).
θg, F = (n _g −n _F ) / (n _F −n _C ) (1)

In optical glass, there is an approximately linear relationship between a partial dispersion ratio (θg, F) representing partial dispersion in a short wavelength region and an Abbe number (ν _d ). The straight line representing this relationship plots the partial dispersion ratio and Abbe number of NSL7 and PBM2 on the Cartesian coordinates employing the partial dispersion ratio (θg, F) on the vertical axis and the Abbe number (ν _d ) on the horizontal axis. It is represented by a straight line connecting two points and is called a normal line (see FIG. 1). Normal glass, which is the standard for normal lines, differs depending on the optical glass manufacturer, but each company defines it with almost the same slope and intercept. (NSL7 and PBM2 are optical glasses manufactured by OHARA, Inc., and the Abbe number (ν _d ) of PBM2 is 36.3, the partial dispersion ratio (θg, F) is 0.5828, and the Abbe number (ν _d ) of NSL7. Is 60.5, and the partial dispersion ratio (θg, F) is 0.5436.)

  Here, as glass having high dispersion, for example, optical glasses as shown in Patent Documents 1 to 3 are known.

JP 2003-104752 A JP 2010-006676 A JP 09-208250 A

  However, the glasses disclosed in Patent Documents 1 to 3 have a small partial dispersion ratio and are not sufficient for use as a lens for correcting the secondary spectrum. That is, an optical glass having a high dispersion and a small partial dispersion ratio (θg, F) is required.

  Further, the glasses disclosed in Patent Documents 1 to 3 have a problem of solarization in which the spectral transmittance is reduced by ultraviolet rays contained in sunlight or the like. Since the glass having a large solarization is colored by being irradiated with ultraviolet rays for a long time, it has been difficult to maintain a desired spectral transmittance at the beginning of manufacture.

The present invention has been made in view of the above-mentioned problems. The object of the present invention is to achieve a partial dispersion ratio (n _d ) and an Abbe number (ν _d ) within a desired range. An object of the present invention is to obtain an optical glass having a small θg, F) and in which deterioration of the spectral transmittance with time is suppressed, and a preform and an optical element using the optical glass.

In order to solve the above-mentioned problems, the present inventors have conducted earnest test research. As a result, the SiO ₂ component and the Nb ₂ O ₅ component are used in combination, and the content of these components is set within a predetermined range. While achieving a high refractive index and high dispersion, the partial dispersion ratio (θg, F) of the glass has a desired relationship with the Abbe number (ν _d ), and solarization of the glass is reduced. As a result, the present invention has been completed. Specifically, the present invention provides the following.

(1) With respect to the total glass mass of the oxide equivalent composition, it contains 10.0 to 40.0% of SiO ₂ component and 1.0 to 50.0% of Nb ₂ O ₅ component in mass%, (−0.00160 × ν _d ) having an Abbe number (ν _d ) of 15 to 30 and a partial dispersion ratio (θg, F) in the range of ν _d ≦ 25 with respect to the Abbe number (ν _d ). +0.63460) ≦ (θg, F) ≦ (−0.00480 × ν _d +0.73500), and in the range of ν _d > 25, (−0.00250 × ν _d +0.65710) ≦ (θg , F) ≦ (−0.00250 × ν _d +0.677750).

(2) the entire mass of the glass in terms of oxide composition, the content of TiO ₂ component in terms of mass% is less than 35.0% (1), wherein the optical glass.

(3) The optical glass according to (2), wherein the mass ratio (TiO ₂ ) / (Nb ₂ O ₅ ) of the oxide equivalent composition is greater than 0.05 and less than 0.80.

(4) the entire mass of the glass in terms of oxide composition, _Ta mass% 2 _{O 5} component from 0 to 15.0% and / or WO ₃ components from 0 to 25.0% and / or _Bi 2 _{O 3} component 0 ~ 25.0% and / or BaO component 0 ~ 20.0%
The optical glass according to any one of (1) to (3), further comprising:

(5) The mass sum (WO ₃ + Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ + Bi ₂ O ₃ + BaO) with respect to the total glass mass of the oxide equivalent composition is 65.0% or less, and any of (1) to (4) Or an optical glass.

(6) B ₂ O ₃ component 0 to 20.0% and / or P ₂ O ₅ component 0 to 10.0% and / or GeO ₂ component in mass% with respect to the total glass mass of the oxide equivalent composition 0 ~ 10.0%
The optical glass according to any one of (1) to (5), further comprising:

(7) Li ₂ O component from 0 to 20.0% and / or Na ₂ O component from 0 to 20.0% and / or _{K 2} O ingredient from 0 to 20.0% and / or Cs ₂ O components 0-10. 0%
The optical glass according to any one of (1) to (6), further containing each component of

(8) The mass sum of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, K and Cs) with respect to the total glass mass of the oxide equivalent composition is 2.0% or more and 30 Optical glass as described in (7) which is 0.0% or less.

(9) The mass sum (SiO ₂ + P ₂ O ₅ + B ₂ O ₃ + GeO ₂ + Li ₂ O + Na ₂ O + K ₂ O + Cs ₂ O) with respect to the total glass mass of the oxide conversion composition is less than 49.0% from (6) to ( The optical glass according to any one of 8).

(10) Sum of mass (WO ₃ + Nb ₂ O ₅ + TiO ₂ + Ta) with respect to the total mass of the glass in terms of oxide (SiO ₂ + P ₂ O ₅ + B ₂ O ₃ + GeO ₂ + Li ₂ O + Na ₂ O + K ₂ O + Cs ₂ O) The optical glass according to (9), wherein a value divided by ₂ O ₅ + Bi ₂ O ₃ + BaO) is 0.10 or more and less than 1.00.

(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% Component 0 to 10.0% and / or Yb ₂ O ₃ component 0 to 10.0% and / or Lu ₂ O ₃ component 0 to 10.0%
The optical glass according to any one of (1) to (10), further containing each component of

(12) The mass sum of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of Y, La, Gd, Yb and Lu) with respect to the total glass mass of the oxide equivalent composition is 15.0 % Or less of the optical glass according to (11).

(13) The mass sum of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of Y, La, Gd, Yb and Lu) with respect to the total glass mass of the oxide equivalent composition is 8.5. % Or less of the optical glass according to (11).

(14) The mass ratio (TiO ₂ + Bi ₂ O ₃ ) / (WO ₃ + Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ + Bi ₂ O ₃ ) of the oxide equivalent composition is 0.80 or less (1) to (13 ) Any one of the optical glasses.

(15) MgO component 0 to 20.0% and / or CaO component 0 to 20.0% and / or SrO component 0 to 20.0% and / Or ZnO component 0 to 20.0%
The optical glass according to any one of (1) to (14), further comprising:

  (16) The mass sum of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) with respect to the total glass mass of the oxide equivalent composition is 25.0% or less ( 15) The optical glass as described.

(17) as oxide entire mass of the glass composition, _Al 2 _{O 3} component from 0 to 10.0% and / or ZrO ₂ component from 0 to 20.0% and / or TeO ₂ components 0-10 mass% 0.0% and / or CeO ₂ 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 (16), further containing each component of

  (18) A preform for polishing and / or precision press molding comprising the optical glass according to any one of (1) to (17).

  (19) An optical element obtained by polishing the preform described in (18).

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

According to the present invention, the SiO ₂ component and the Nb ₂ O ₅ component are used in combination, and the content of these components is within a predetermined range. Has a desired relationship with the Abbe number (ν _d ), and the solarization of the glass is reduced. Also, a combination of SiO ₂ component and Nb ₂ O ₅ component, by these content within a predetermined range, devitrification during reheating of the glass is reduced. Accordingly, an optical system in which the refractive index (n _d ) and the Abbe number (ν _d ) are within a desired range, the chromatic aberration is small, the spectral transmittance is prevented from being deteriorated over time, and mold press molding is easy to perform. Glass, a preform using the glass, and an optical element can be obtained.

It is a figure which shows the normal line by which partial dispersion ratio ((theta) g, F) is represented on the orthogonal coordinate of a vertical axis | shaft and Abbe number ((nu) _d ) on a horizontal axis. It is a figure which shows the relationship between the partial dispersion ratio ((theta) g, F) and the Abbe number ((nu) _d ) about the glass of the Example of this application.

In the optical glass of the present invention, the SiO ₂ component is 10.0 to 40.0% and the Nb ₂ O ₅ component is 1.0 to 50.0% by mass with respect to the total mass of the oxide-converted glass. % containing, have 15 to 30 of Abbe number ([nu _d), the partial dispersion ratio ([theta] g, F) between the Abbe number ([nu _d), in the region of ν _d ≦ 25 (-0. _{00160 × ν d +0.63460) ≦ (} θg, F) ≦ ( satisfying the relationship _{-0.00480 × ν d +0.73500), ν} d> in a range of 25 (-0.00250 × ν _d +0.65710 ) ≦ (θg, F) ≦ (−0.00250 × ν _d +0.67750). The SiO ₂ component and the Nb ₂ O ₅ component are used in combination, and by making these contents within a predetermined range, the partial dispersion ratio (θg, F) is reduced while the glass has a high refractive index and high dispersion. Deterioration of the light transmittance after the glass is irradiated with ultraviolet rays and devitrification and / or white turbidity after the glass is reheated are reduced. For this reason, an optical glass that has an Abbe number (ν _d ) of 30 or less, is easy to perform mold press molding, has small chromatic aberration, and suppresses temporal degradation of spectral transmittance, and the same are used. Preforms and optical elements can be obtained.

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

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

<About essential and optional components>
The SiO ₂ component is a glass-forming oxide and is a useful component for forming a glass skeleton. In particular, by setting the content of the SiO ₂ component to 10.0% or more, the glass network structure increases to such an extent that a stable glass can be obtained, so that the devitrification resistance of the glass can be improved. On the other hand, when the content of the SiO ₂ component is 40.0% or less, the refractive index of the glass is hardly lowered, and an optical glass having a desired 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 15.0%, most preferably 20.0%, and preferably 40.0%. %, More preferably 38.0%, and most preferably 35.0%. SiO ₂ component may be contained in the glass by using as a raw material such as _{SiO 2, K 2 SiF 6,} Na 2 SiF 6 or the like.

The Nb ₂ O ₅ component is a component that decreases the partial dispersion ratio (θg, F) of the glass while increasing the refractive index and dispersion of the glass. In particular, by containing 1.0% or more of the Nb ₂ O ₅ component, it is possible to easily obtain a partial dispersion ratio (θg, F) close to a normal line while obtaining a desired high refractive index and high dispersion. Therefore, the content of the Nb ₂ O ₅ component is preferably 1.0%, more preferably 10.0%, still more preferably 20.0%, and most preferably 30.0% with respect to the total glass mass of the oxide equivalent composition. % Is the lower limit. On the other hand, by making the content of the Nb ₂ O ₅ component 50.0% or less, solarization of the glass is reduced, so that it is easy to obtain an optical glass in which the deterioration of spectral transmittance with time is suppressed. it can. Further, by setting the content of Nb ₂ O ₅ component below 50.0%, since the devitrification of the glass due to reheating is reduced, it is possible to easily obtain the easy optical glass perform press molding. Therefore, the content of the Nb ₂ O ₅ component with respect to the total glass mass of the oxide conversion composition is preferably 50.0%, more preferably 45.0%, still more preferably 40.0%, and most preferably 36.0. % Is the upper limit. 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 lowers the Abbe number while increasing the refractive index of the glass, and is an optional component in the optical glass of the present invention. In particular, by making the content of the TiO ₂ component less than 35.0%, it is possible to make it difficult to deteriorate the internal transmittance particularly in the visible short wavelength (500 nm or less) by reducing the coloration on the glass. Further, by making the content of the TiO ₂ component less than 35.0%, it becomes difficult to increase the partial dispersion ratio (θg, F), so that it is easy to obtain the partial dispersion ratio (θg, F) close to the normal line. be able to. Therefore, the content of the TiO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably less than 35.0%, more preferably 30.0%, and most preferably 25.0%. In the present invention without containing TiO ₂ component, although it is possible to obtain an optical glass having desired optical properties, by containing a TiO ₂ component, it is possible to increase the refractive index and dispersion of the glass . Therefore, the content of the TiO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably more than 0%, more preferably 1.0%, and most preferably 5.0%. TiO ₂ component may be contained in the glass by using as the starting material for example TiO ₂ or the like.

In the optical glass of the present invention, the ratio of the content of the TiO ₂ component to the content of the Nb ₂ O ₅ component is preferably less than 0.80. Thereby, since the solarization of the optical glass is reduced, it is possible to easily obtain the optical glass in which the temporal degradation of the spectral transmittance is suppressed. Therefore, the mass ratio (TiO ₂ ) / (Nb ₂ O ₅ ) of the oxide equivalent composition is preferably less than 0.80, more preferably 0.60, even more preferably 0.50, and most preferably 0.44. Is the upper limit. Even if this mass ratio is 0, an optical glass having desired optical properties can be obtained, but the ratio of the content of the TiO ₂ component to the content of the Nb ₂ O ₅ component is larger than 0.05. By doing so, since stability of glass is improved, devitrification at the time of forming glass and devitrification at the time of reheating glass can be reduced. Therefore, the mass ratio (TiO ₂ ) / (Nb ₂ O ₅ ) of the oxide equivalent composition is preferably 0.05, more preferably 0.10, and most preferably 0.15.

The Ta ₂ O ₅ component is a component that increases the refractive index of the glass and decreases the devitrification temperature of the glass, and is an optional component in the optical glass of the present invention. In particular, the devitrification resistance of the glass can be maintained by setting the content of the Ta ₂ O ₅ component to 15.0% or less. Therefore, the content of the Ta ₂ O ₅ component with respect to the total glass mass of the oxide conversion composition is preferably 15.0%, more preferably 12.0%, and most preferably 10.0%. The 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 lowers the devitrification temperature 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 25.0% or less, it is possible to make it difficult to deteriorate the transmittance particularly in the visible short wavelength (500 nm or less). Further, by setting the content of the WO ₃ component to 25.0% or less, the partial dispersion ratio (θg, F) can be hardly increased. Therefore, the content of the WO ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 25.0%, more preferably 20.0%, and most preferably 15.0%. In particular, in terms of obtaining a glass having a low partial dispersion ratio and high resistance to devitrification during reheating, the content of the WO ₃ component with respect to the total glass mass of the oxide conversion composition is 6.0% or less. Most preferred. The WO ₃ component can be contained in the glass using, for example, WO ₃ as a raw material.

The Bi ₂ O ₃ component is a component that increases the refractive index of the glass and lowers the glass transition point (Tg), and is an optional component in the optical glass of the present invention. In particular, the internal transmittance of the glass can be increased by reducing the coloring of the glass by setting the content of the Bi ₂ O ₃ component to 25.0% or less. Further, by setting the content of _Bi 2 _{O 3} component below 25.0% can be difficult to increase the partial dispersion ratio ([theta] g, F). Therefore, the content of the Bi ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 25.0%, more preferably 20.0%, and even more preferably 10.0%. In particular, in terms of obtaining a glass having a low partial dispersion ratio, the content of the Bi ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is most preferably 6.0% or less. The Bi ₂ O ₃ component can be contained in the glass using, for example, Bi ₂ O ₃ as a raw material.

The BaO component is a component that lowers the devitrification temperature of the glass and adjusts the optical constant of the glass, and is an optional component in the optical glass of the present invention. In particular, the devitrification resistance of the glass can be improved by setting the content of the BaO component to 20.0% or less. Further, by making the content of the BaO component 20.0% or less, it is possible to make it difficult to increase the partial dispersion ratio (θg, F), and to improve the devitrification resistance of the glass during reheating. it can. Accordingly, the content of the BaO component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 15.0%, still more preferably 10.0%, and most preferably 6.0%. And The BaO component can be contained in the glass using, for example, BaCO ₃ , Ba (NO ₃ ) ₂ or the like as a raw material.

In the optical glass of the present invention, the total content of the WO ₃ component, the Nb ₂ O ₅ component, the TiO ₂ component, the Ta ₂ O ₅ component, the Bi ₂ O ₃ component, and the BaO component may be 65.0% or less. preferable. Thereby, since stability of optical glass is improved, devitrification resistance at the time of forming glass and devitrification resistance at the time of reheating glass can be improved. At the same time, it is possible to easily obtain a low partial dispersion ratio (θg, F) close to the normal line, which is desired in the present invention. Therefore, the mass sum (WO ₃ + Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ + Bi ₂ O ₃ + BaO) with respect to the total glass mass of the oxide conversion composition is preferably 65.0%, more preferably 60.0%. And most preferably less than 55.0%. On the other hand, by containing at least one of these components, the refractive index of the glass is increased, so that a desired high refractive index can be easily obtained. Accordingly, the mass sum (WO ₃ + Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ + Bi ₂ O ₃ + BaO) with respect to the total glass mass of the oxide conversion composition is preferably 10.0%, more preferably 20.0%, most preferably Preferably, the lower limit is 30.0%.

The B ₂ O ₃ component is a glass-forming oxide, a component useful for forming a glass skeleton, and an optional component in the optical glass of the present invention. In particular, when the content of the B ₂ O ₃ component is 20.0% or less, the refractive index of the glass is hardly lowered, and the internal transmittance in the visible light short wavelength region is hardly deteriorated. Therefore, the content of the B ₂ O 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 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.

P ₂ O ₅ component is a component which enhances the stability of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of the P ₂ O ₅ component to 10.0% or less, the devitrification tendency due to the excessive content of the P ₂ O ₅ component is reduced, so that the stability of the glass can be enhanced. Therefore, the content of the P ₂ O ₅ component with respect to the total glass mass of the oxide conversion composition is preferably 10.0%, more preferably 7.0%, and most preferably 5.0%. The 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. .

The GeO ₂ component is a component that increases the refractive index of the glass and stabilizes the glass to reduce devitrification during molding, and is an optional component in the optical glass of the present invention. In particular, by making the content of the GeO ₂ component 10.0% or less, the amount of expensive GeO ₂ component used is reduced, so that the material cost of the glass can be reduced. 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.

The Li ₂ O component is a component that lowers the partial dispersion ratio (θg, F) of the glass, lowers the devitrification temperature of the glass, and lowers the glass transition point (Tg), and is an optional component in the optical glass of the present invention. It is. In particular, when the content of the Li ₂ O component is 20.0% or less, solarization becomes difficult to increase, so that an optical glass with reduced solarization can be easily obtained. 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%. Although an optical glass having desired physical properties can be produced without containing a Li ₂ O component, the glass has a desired low value of the partial dispersion ratio (θg, F) while ensuring a low glass transition point (Tg). From the viewpoint of easy adjustment, the content of the Li ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 0.1%, more preferably 0.5%, and most preferably 1.0%. And 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 increases the chemical durability of the glass, particularly water resistance, and is a component that lowers the glass transition point (Tg), and is an optional component in the optical glass of the present invention. In particular, when the content of the Na ₂ O component is 20.0% or less, the stability of the glass is enhanced, and therefore glass devitrification due to excessive inclusion of the Na ₂ O component can be reduced. Therefore, the content of the Na ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. In the present invention, an optical glass having desired physical properties can be produced without containing a Na ₂ O component, but from the viewpoint of further improving the devitrification resistance of the glass, it is based on the total mass of the oxide-converted composition. The content of the Na ₂ O component is preferably 0.1%, more preferably 1.0%, and most preferably 4.0%. The Na ₂ O component can be contained in the glass using, for example, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ or the like as a raw material.

K 2 _O component is a component for glass transition point (Tg) lower, are optional components of the optical glass of the present invention. In particular, by setting the content of the K ₂ O component to 20.0% or less, devitrification of the glass due to excessive inclusion of the K ₂ O component can be reduced. 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 10.0%, and even more preferably 5.0%. In particular, from the viewpoint of improving the devitrification resistance during reheating, the content of the K ₂ O component with respect to the total glass mass of the oxide conversion composition is most preferably 2.4% or less. 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.

Cs 2 _O component is a component for glass transition point (Tg) lower, are optional components of the optical glass of the present invention. In particular, when the content of the Cs ₂ O component is 10.0% or less, a desired refractive index and Abbe number can be easily realized. Further, by setting the content of Cs ₂ O component to 10.0% or less, it can be reduced devitrification of the glass due to excessive content of Cs ₂ O component. Therefore, the upper limit of the content of the Cs ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 10.0%, more preferably 8.0%, and even more preferably 5.0%. Cs ₂ O component may be contained in the glass by using as the starting material for example _Cs 2 _{CO 3,} CsNO 3, and the like.

In the optical glass of the present invention, the mass sum of the contents of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, K and Cs) is 2.0% or more and 30.30. It is preferably 0% or less. In particular, by setting the mass sum to 2.0% or more, it is possible to obtain a glass that is easy to press-mold by lowering the glass transition point (Tg). Accordingly, the total content of the Rn ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 2.0%, more preferably 5.0%, and most preferably 10.0%. On the other hand, by making this mass sum 30.0% or less, vitrification can be facilitated by suppressing an increase in the devitrification temperature of the glass. Therefore, the mass sum of the content of the Rn ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 30.0%, more preferably 25.0%, and most preferably 20.0%.

Further, in the optical glass of the present invention preferably the ratio of the Li ₂ O content component to the content of Rn ₂ O component is 0.25 or more 0.98 or less. In particular, by setting this ratio to 0.25 or more, the content of the Li ₂ O component that lowers the partial dispersion ratio increases, so that a desired low partial dispersion ratio can be easily obtained. On the other hand, by setting this ratio to 0.98 or less, since a plurality of types of alkali metal components are contained in the glass, the stability of the glass can be improved, and devitrification of the glass during reheating can be reduced. . Therefore, the mass ratio (Li ₂ O / Rn ₂ O) in the oxide-converted composition is preferably 0.25, more preferably 0.30, and most preferably 0.35. On the other hand, the mass ratio (Li ₂ O / Rn ₂ O) in the oxide equivalent composition is preferably 0.98, more preferably 0.90, and most preferably 0.80.

The optical glass of the present invention preferably has a mass sum (SiO ₂ + P ₂ O ₅ + B ₂ O ₃ + GeO ₂ + Li ₂ O + Na ₂ O + K ₂ O + Cs ₂ O) of less than 49.0%. As a result, the refractive index and the Abbe number are unlikely to decrease, so that a desired high refractive index and high dispersion can be easily obtained. Therefore, the mass sum (SiO ₂ + P ₂ O ₅ + B ₂ O ₃ + GeO ₂ + Li ₂ O + Na ₂ O + K ₂ O + Cs ₂ O) with respect to the total glass mass of the oxide equivalent composition is preferably less than 49.0%, more preferably The upper limit is 48.0%, and most preferably 47.0%. On the other hand, this mass sum is preferably 20.0% or more. As a result, an increase in the partial dispersion ratio (θg, F) can be suppressed, and a low partial dispersion ratio (θg, F) close to the normal line, which is desired in the present invention, can be easily obtained. Further, since the stability of the glass is enhanced, the devitrification resistance when the glass is reheated can be enhanced. Therefore, the mass sum (SiO ₂ + P ₂ O ₅ + B ₂ O ₃ + GeO ₂ + Li ₂ O + Na ₂ O + K ₂ O + Cs ₂ O) with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 30. The lower limit is 0%, more preferably 35.0%, and most preferably 41.0%.

The optical glass of the present invention is obtained by adding the mass sum (SiO ₂ + P ₂ O ₅ + B ₂ O ₃ + GeO ₂ + Li ₂ O + Na ₂ O + K ₂ O + Cs ₂ O) to the mass sum (WO ₃ + Nb ₂ O ₅ + TiO ₂ + Ta ₂ O _5). The value divided by + Bi ₂ O ₃ + BaO) is preferably 0.10 or more and less than 1.00. Inclusion of a component that can lower the partial dispersion ratio (θg, F) of the glass relative to the content of the component that can increase the partial dispersion ratio (θg, F) of the glass by setting this ratio to 0.10 or more. Since the ratio of the amount is increased, a glass having a desired partial dispersion ratio (θg, F) can be obtained. On the other hand, by making this ratio less than 1.00, the ratio of the content of components that can lower the refractive index of the glass is reduced with respect to the content of components that increase the refractive index of the glass. It is easy to obtain a high refractive index. Therefore, the mass ratio (SiO ₂ + P ₂ O ₅ + B ₂ O ₃ + GeO ₂ + Li ₂ O + Na ₂ O + K ₂ O + Cs ₂ O) / (WO ₃ + Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ + Bi ₂ O ₃ ) in the oxide equivalent composition + BaO) is preferably 0.10, more preferably 0.15, most preferably 0.20 as the lower limit, preferably less than 1.00, more preferably 0.97, and most preferably 0.94. To do.

Y ₂ O ₃ component, while increasing the refractive index of the glass, or to enhance the devitrification resistance of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of the Y ₂ O ₃ component to 10.0% or less, the devitrification resistance of the glass can be increased, and the dispersion of the glass can be made difficult to decrease. 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%. For the Y ₂ O ₃ component, for example, Y ₂ O ₃ , YF ₃ or the like can be used as a raw material.

The La ₂ O ₃ component is a component that increases the Abbe number of the glass while increasing the refractive index of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the La ₂ O ₃ component to 10.0% or less, the devitrification resistance of the glass can be increased, and the dispersion of the glass can be made difficult to decrease. 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%. As the La ₂ O ₃ component, for example, La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ O (X is an arbitrary integer) or the like can be used as a raw material.

The Gd ₂ O ₃ component is a component that increases the Abbe number of the glass while increasing the refractive index of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the Gd ₂ O ₃ component to 10.0% or less, the devitrification resistance of the glass can be increased, and the dispersion of the glass can be made difficult to decrease. 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%. As the Gd ₂ O ₃ component, for example, Gd ₂ O ₃ , GdF ₃ or the like can be used as a raw material.

The Yb ₂ O ₃ component is a component that realizes a high refractive index and improves properties such as hardness and Young's modulus. In particular, by setting the content of the Yb ₂ O ₃ component to 10.0% or less, it is possible to suppress a decrease in the dispersion of the glass and to improve the devitrification resistance at the time of glass formation. Therefore, the content of the Yb 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 Lu ₂ O ₃ component is a component that realizes a high refractive index and improves properties such as hardness and Young's modulus. In particular, by making the content of the Lu ₂ O ₃ component 10.0% or less, it is possible to suppress a decrease in the dispersion of the glass and to improve the devitrification resistance at the time of glass formation. Therefore, the content of the Lu 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%.

In the optical glass of the present invention, the mass sum of the content of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, Yb and Lu) is 15.0%. The following is preferable. By making this mass sum 15.0% or less, devitrification resistance when the glass is reheated can be enhanced while suppressing a decrease in dispersion of the glass. Therefore, the mass sum of the content of the Ln ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 15.0%, more preferably 10.0%, still more preferably 8.5%, and most preferably. The upper limit is 5.0%.

Further, the optical glass of the present invention, it is preferred weight sums for the mass sum _{(WO 3 + Nb 2 O 5} + TiO 2 + Ta 2 O 5 + Bi 2 O 3) (TiO 2 + Bi 2 O 3) is 0.80 or less . Accordingly, since the content of the coloring easily TiO ₂ component and Bi ₂ O ₃ component of the glass among the components to enhance the partial dispersion ratio is reduced, it is possible to reduce the coloring while obtaining the desired partial dispersion ratio . Therefore, the mass ratio (TiO ₂ + Bi ₂ O ₃ ) / (WO ₃ + Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ + Bi ₂ O ₃ ) of the oxide equivalent composition is preferably 0.80, more preferably 0.70. Most preferably, the upper limit is 0.65.

The MgO component is a component that lowers the melting temperature 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 20.0% or less, the chemical durability of the glass can be enhanced while obtaining a desired high refractive index. Therefore, the content of the MgO component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 10.0%, and most preferably 7.0%. The MgO component can be contained in the glass using, for example, MgO, MgCO ₃ , MgF ₂ or the like as a raw material.

The CaO component is a component that lowers the devitrification temperature 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 20.0% or less, the chemical durability of the glass can be enhanced while obtaining a desired high refractive index. Therefore, the content of the CaO component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. 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 devitrification temperature of the glass and adjusts the refractive index of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the SrO component to 20.0% or less, it is possible to improve the devitrification resistance of the glass while obtaining a desired high refractive index. Therefore, the content of the SrO component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. 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.

The ZnO component is a component that lowers the devitrification temperature of the glass and lowers the glass transition point (Tg), and is an optional component in the optical glass of the present invention. In particular, by setting the content of the ZnO component to 20.0% or less, the chemical durability of the glass can be enhanced while obtaining a desired high refractive index. Therefore, the content of the ZnO component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. The ZnO component can be contained in the glass using, for example, ZnO, ZnF ₂ or the like as a raw material.

  In the optical glass of the present invention, the RO component (wherein R is one or more selected from the group consisting of Zn, Mg, Ca, Sr, and Ba) increases the devitrification resistance of the glass as described above, Although it is a component useful for adjusting the refractive index, if the total content of these RO components is too large, the devitrification resistance of the glass tends to deteriorate, and the refractive index of the glass tends to decrease. Therefore, the total content of the RO component with respect to the total glass mass of the oxide conversion composition is preferably 25.0%, more preferably 20.0%, and most preferably 10.0%. Here, from the viewpoint of easily obtaining a desired low partial dispersion ratio, the proportion of the BaO component in the RO component is preferably 80% or less, more preferably 70% or less, and most preferably 60% or less.

The Al ₂ O ₃ component is a component that improves the chemical durability of the glass, and is an optional component in the optical glass of the present invention. In particular, the devitrification resistance of the glass can be enhanced by setting the content of the Al ₂ O ₃ component to 10.0% or less. Therefore, the upper limit of the content of the Al 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 Al ₂ O ₃ component can be contained in the glass using, for example, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ or the like as a raw material.

The ZrO ₂ component is a component that lowers the partial dispersion ratio (θg, F) of the glass while increasing the refractive index of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the ZrO ₂ component to 20.0% or less, the liquidus temperature of the glass can be lowered to increase the devitrification resistance. Therefore, the content of the ZrO ₂ 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 ZrO ₂ component can be contained in the glass using, for example, ZrO ₂ , ZrF ₄ or the like as a raw material.

TeO ₂ component increases the refractive index of the glass is a component of glass transition point (Tg) lower, are optional components of the optical glass of the present invention. In particular, by setting the content of the TeO ₂ component to 10.0% or less, the coloring of the glass can be reduced and the internal transmittance of the glass can be increased. Therefore, the content of the TeO 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 TeO ₂ component can be contained in the glass using, for example, TeO ₂ as a raw material.

The CeO ₂ component is a component that adjusts the optical constant of the glass and improves the solarization of the glass, and is an optional component in the optical glass of the present invention. In particular, when the content of the CeO ₂ component is 10.0% or less, it is possible to easily obtain a glass having a small solarization. Therefore, the CeO ₂ component content with respect to the total glass mass of the oxide conversion composition is preferably 10.0%, more preferably 5.0%, and most preferably 1.0%. However, when a CeO ₂ component is contained, absorption tends to occur at a specific wavelength in the visible range. Therefore, it is preferable that the CeO ₂ component is not substantially contained in terms of coloring of the glass. The CeO ₂ component can be contained in the glass using, for example, CeO ₂ as a raw material.

The Sb ₂ O ₃ component is a component that accelerates defoaming of the glass and clarifies the glass, and is an optional component in the optical glass of the present invention. Sb ₂ O ₃ component, by a content relative to the glass total weight 1.0% or less, can be hardly caused excessive foaming during glass melting, _Sb 2 _{O 3} ingredient is dissolved facilities (especially Pt And the like can be made difficult to alloy. Therefore, the content of the Sb ₂ O ₃ component with respect to the total glass mass of the oxide-converted composition is preferably 1.0%, more preferably 0.8%, and still more preferably 0.6%. Here, from the viewpoint of easily obtaining an optical glass particularly low in solarization, the content of the Sb ₂ O ₃ component with respect to the total glass mass of the oxide-converted composition is preferably 0.5%, more preferably 0.3%, Most preferably, the upper limit is 0.2%. Incidentally, the content of _Sb 2 _{O 3} component is particularly disadvantageous not technically Within this range, the content of _Sb 2 _{O 3} component by more than 0%, _Sb 2 _{O 3} Solarization can be made lower than when no component is contained. Therefore, the content of the Sb ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably more than 0%, more preferably 0.0001%, and most preferably 0.001%. However, when importance is attached to the environmental impact of the optical glass, it is preferable not to contain the Sb ₂ O ₃ component. 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 of the fining defoaming of glass is not limited to the above Sb ₂ O ₃ ingredients may be used known refining agents and defoamers in the field of glass production, 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 are not impaired.

  However, the transition metal components such as V, Cr, Mn, Co, Ni, Cu, Ag, and Mo, excluding Ti, Zr, and Nb, are colored by the glass even when each of them is contained alone or in combination. Since it has a property of causing absorption at a specific wavelength in the visible range, it is preferable that the optical glass using the wavelength in the visible range does not substantially contain.

Furthermore, lead compounds such as PbO, arsenic compounds such as As ₂ O ₃ , and components of Th, Cd, Tl, Os, Be, and Se have been refraining from being used as harmful chemical substances in recent years. Environmental measures are required not only in the manufacturing process but also in the processing process and disposal after commercialization. Therefore, when importance is placed on the environmental impact, it is preferable not to substantially contain them except for inevitable mixing. As a result, the optical glass is substantially free of substances that pollute the environment. Therefore, the optical glass can be manufactured, processed, and discarded without taking any special environmental measures.

The glass that is preferably used as the optical glass of the present invention cannot be expressed directly in the description of mol% because the composition is represented by mass% with respect to the total mass of the glass in terms of oxide composition, but is required in the present invention. The composition expressed by mol% of each component present in the glass composition satisfying various properties generally takes the following values in terms of oxide conversion.
SiO ₂ component from 15.0 to 60.0 mol% and _Nb 2 _{O 5} ingredient 0.5 to 20.0 mol%
And TiO ₂ component from 0 to 40.0 mol% and / or _Ta 2 _{O 5} component 0-4.0 mol% and / or WO ₃ components 0 to 10.0 mol% and / or _Bi 2 _{O 3} component 0-5 2.0 mol% and / or BaO components from 0 to 15.0 mol% and / or _B 2 _{O 3} component from 0 to 30.0 mol% and / or _P 2 _{O 5} component from 0 to 7.0 mol% and / or GeO _2-component 0-5.0 mol% and / or Li ₂ O component from 0 to 55.0 mol% and / or Na ₂ O component from 0 to 30.0 mol% and / or _{K 2} O component 0 to 20.0 mol % and / or Cs ₂ O components 0 to 4.0 mol% and / or _Y 2 _{O 3} component 0-4.0 mol% and / or _La 2 _{O 3} component 0-3.0 mol% and / or Gd ₂ O ₃ component 0-3.0 mol% and / or _Yb 2 _{O 3} component 0-3.0 mol% and / or u ₂ O ₃ component 0-3.0 mol% and / or MgO component from 0 to 50.0 mol% and / or CaO component from 0 to 40.0 mol% and / or SrO component 0 to 20.0 mol% and / or ZnO component from 0 to 25.0 mol% and / or _Al 2 _{O 3} component 0 to 10.0 mol% and / or ZrO ₂ component from 0 to 15.0 mol% and / or TeO ₂ components 0 to 7.0 moles % And / or CeO ₂ component 0-3.0 mol% and / or Sb ₂ O ₃ component 0-0.3 mol%

[Production method]
The optical glass of the present invention is produced, for example, as follows. That is, the above raw materials are uniformly mixed so that each component is within a predetermined content range, and the prepared mixture is put into a platinum crucible, a quartz crucible or an alumina crucible and roughly melted, then a gold crucible, a platinum crucible In a platinum alloy crucible or iridium crucible, melt in a temperature range of 1100 to 1400 ° C. for 3 to 4 hours, stir to homogenize, blow off bubbles, etc., then lower the temperature to 1000 to 1200 ° C. and then finish stirring This is done by removing the striae, casting into a mold and slow cooling.

<Physical properties>
The optical glass of the present invention preferably has a predetermined refractive index and dispersion (Abbe number). More specifically, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.77, more preferably 1.79, and most preferably 1.81. On the other hand, the upper limit of the refractive index (n _d ) of the optical glass of the present invention is not particularly limited, but is generally 2.20 or less, more specifically 2.10 or less, and more specifically 2.00 or less. There are many. Further, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 30, more preferably 29, and most preferably 28. On the other hand, the lower limit of the Abbe number (ν _d ) of the optical glass of the present invention is not particularly limited, but is generally about 10 or more, more specifically 12 or more, and more specifically 15 or more. 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.

Moreover, the optical glass of the present invention has a low partial dispersion ratio (θg, F). More specifically, the partial dispersion ratio (θg, F) of the optical glass of the present invention is (−0.00160 × ν _d +0...) In the range of ν _d ≦ 25 with respect to the Abbe number (ν _d ). 63460) ≦ (θg, F) ≦ (−0.00480 × ν _d +0.73500), and (−0.00250 × ν _d +0.65710) ≦ (θg) in the range of ν _d > 25. , F) ≦ (−0.00250 × ν _d +0.67750). As a result, an optical glass having a partial dispersion ratio (θg, F) close to the normal line can be obtained while having low solarization, so that chromatic aberration of an optical element formed from this optical glass can be reduced over a long period of time. it can. Here, the lower limit of the partial dispersion ratio (θg, F) of the optical glass at ν _d ≦ 25 is preferably (−0.00160 × ν _d +0.63460), more preferably (−0.00160 × ν _d +0). .63660), most preferably (−0.00160 × ν _d +0.63860). On the other hand, the upper limit of the partial dispersion ratio (θg, F) of the optical glass at ν _d ≦ 25 is preferably (−0.00480 × ν _d +0.73500), more preferably (−0.00480 × ν _d +0). 73323), and most preferably (−0.00480 × ν _d +0.73100). The partial dispersion ratio (θg, F) of the optical glass at ν _d > 25 is preferably (−0.00250 × ν _d +0.65710), more preferably (−0.00250 × ν _d +0.65910). Most preferably, the lower limit is (−0.00250 × ν _d +0.66110). On the other hand, the upper limit of the partial dispersion ratio (θg, F) of the optical glass at ν _d > 25 is preferably (−0.00250 × ν _d +0.67750), more preferably (−0.00250 × ν _d +0). .67573), most preferably (−0.00250 × ν _d +0.67350). In particular, in a region where the Abbe number (ν _d ) is small, the partial dispersion ratio (θg, F) of general glass is higher than that of the normal line, and the partial dispersion ratio (θg, F) of general glass is high. And the Abbe number (ν _d ) are represented by curves. However, since it is difficult to approximate this curve, the present invention uses a straight line having a different slope from ν _d = 25 as a partial dispersion ratio (θg, F) lower than that of general glass. Expressed.

Moreover, it is preferable that the optical glass of this invention has little coloring. In particular, the optical glass of the present invention has a wavelength (λ ₇₀ ) of 460 nm or less, more preferably 440 nm or less, and most preferably, when the sample has a thickness of 10 mm and exhibits a spectral transmittance of 70%. Is 420 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 preferably used as a material for an optical element such as a lens.

  The optical glass of the present invention preferably has a solarization of 5.0% or less. As a result, the device incorporating the optical glass is unlikely to deteriorate in color balance even after long-term use. In particular, since the solarization is greatly reduced as the operating temperature is higher, the optical glass of the present invention is particularly effective when used at high temperatures such as in-vehicle use. Accordingly, the upper limit of solarization of the optical glass of the present invention is preferably 5.0%, more preferably 4.0%, and most preferably 3.0%. In the present specification, “solarization” refers to the amount of degradation of spectral transmittance at 450 nm when glass is irradiated with ultraviolet rays, and specifically, Japanese Optical Glass Industry Association Standard JOGIS04-1994 “Optical”. According to “Measurement Method of Solarization of Glass”, the spectral transmittance before and after being irradiated with light from a high-pressure mercury lamp is measured.

  Moreover, it is preferable that the optical glass of the present invention is easy to perform mold press molding. That is, the optical glass of the present invention is preferably free from milky whiteness and devitrification after a reheating test assuming mold press molding. Thereby, since it is guessed that milk white and devitrification do not arise even if it performs mold press molding, the optical element which has a desired optical characteristic can be produced efficiently using mold press molding.

[Preforms and optical elements]
A glass molded body can be produced from the produced optical glass by means of mold press molding such as reheat press molding or precision press molding. That is, a preform for mold press molding is prepared from optical glass, and after performing reheat press molding on the preform, polishing is performed to prepare a glass molded body, or for example, polishing is performed. The preform can be precision press-molded to produce a glass molded body. In addition, the means for producing the glass molded body is not limited to these means.

  The glass molded body thus produced is useful for various optical elements, and among them, it is particularly preferable to use it for applications of optical elements such as lenses and prisms. As a result, color bleeding due to chromatic aberration in the transmitted light of the optical system provided with the optical element is reduced. Therefore, when this optical element is used in a camera, a photographing object can be expressed more accurately, and when this optical element is used in a projector, a desired image can be projected with higher definition.

Composition of Examples (No. 1 to No. 10) and Comparative Example (No. 1) of the present invention, refractive index (n _d ), Abbe number (ν _d ), partial dispersion ratio (θg, F), Tables 1 and 2 show the results of the wavelength (λ ₇₀ ) at which the spectral transmittance is 70%, solarization, and the reheating test. The following examples are merely for illustrative purposes, and are not limited to these examples. In addition, Example (No. 6) is a reference example of the present invention.

  The glasses of Examples (No. 1 to No. 10) and Comparative Examples (No. 1) of the present invention are all oxides, hydroxides, carbonates, nitrates, fluorides corresponding to the raw materials of the respective components. The raw materials of high purity used in ordinary optical glass such as hydroxide, metaphosphate compound, etc. are selected and weighed so as to have the composition ratios of the examples and comparative examples shown in Table 1 and Table 2. After mixing uniformly, the mixture was put into a platinum crucible and melted in a temperature range of 1100 to 1400 ° C. for 3 to 4 hours in an electric furnace according to the melting difficulty of the glass composition. Thereafter, the temperature was lowered to 1000 to 1200 ° C., and the mixture was homogenized with stirring, cast into a mold, and gradually cooled to produce glass.

Here, the refractive index (n _d ), Abbe number (ν _d ) and partial dispersion ratio (θg, F) of the glass of Examples (No. 1 to No. 10) and Comparative Example (No. 1) are as follows. It measured based on optical glass industry association standard JOGIS01-2003. Then, with respect to the obtained Abbe number (ν _d ) and partial dispersion ratio (θg, F), the slope a in the relational expression (θg, F) = − a × ν _d + b is 0.00160, 0.00250. And the intercept b at 0.00480 was obtained. In addition, the glass used for this measurement used what was processed in the slow cooling furnace by making slow cooling temperature-fall rate into -25 degrees C / hr.

Moreover, the transmittance | permeability of the glass of an Example (No.1-No.10) and a comparative example (No.1) was 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.

  Further, the solarization of the glass of the examples (No. 1 to No. 10) and the comparative example (No. 1) was performed in accordance with the Japan Optical Glass Industry Association Standard JOGIS 04-1994 “Measurement Method of Solarization of Optical Glass”. The change (%) in light transmittance at a wavelength of 450 nm before and after irradiation was measured. Here, the light irradiation was performed by heating an optical glass sample to 100 ° C. and irradiating light with a wavelength of 450 nm for 4 hours using an ultrahigh pressure mercury lamp.

  Moreover, the reheating test of the glass of an Example (No.1-No.10) and a comparative example (No.1) is a refractory material for a prismatic glass sample having a width and thickness of 15 mm and a length of 30 mm. It was placed on top and placed in an electric furnace and reheated. The temperature was raised from room temperature to any one of 650 ° C., 680 ° C. and 700 ° C. in 150 minutes, and kept at that temperature for 30 minutes. Thereafter, the temperature was lowered to room temperature and taken out of the electric furnace, and then the two opposing surfaces of the glass sample were polished, and the inside of the glass sample was visually observed. In this case, Table 1 and Table 2 show the results of the reheating test, in which the glassy white and devitrification were not recognized and the glass transparent and colorless transparent were marked with ◯, and the milky white or devitrified was marked with x. (The blank column is not reheated.)

Table 1 and as represented in Table 2, the optical glasses of Examples of the present invention, those of [nu _d ≦ 25 partial dispersion ratio ([theta] g, F) is (-0.00160 × _{ν d} +0.63460) As described above, more specifically, it was (−0.00160 × ν _d +0.6543) or more. In the case of ν _d > 25, the partial dispersion ratio (θg, F) is (−0.00250 × ν _d +0.657710) or more, more specifically (−0.00250 × ν _d +0.6730) or more. Met. In the other hand, the optical glass of the embodiment of the present invention, the partial dispersion ratio that of _{ν d ≦ 25 (θg, F} ) is (-0.00480 × ν _d +0.73500) or less, and more particularly (- 0.00480 × ν _d +0.73397) or less. In the case of ν _d > 25, the partial dispersion ratio (θg, F) is (−0.00250 × ν _d +0.677750) or less, more specifically, (−0.00250 × ν _d +0.67722) or less. Met. Therefore, it was found that these partial dispersion ratios (θg, F) are within a desired range. On the other hand, the glass of Comparative Example (No. 1) of the present invention had ν _d ≦ 25, but the partial dispersion ratio (θg, F) exceeded (−0.00480 × ν _d +0.73500). Therefore, it was clarified that the optical glass of the example of the present invention has a smaller partial dispersion ratio (θg, F) in the relational expression with the Abbe number (ν _d ) than the glass of the comparative example.

The optical glasses of the examples of the present invention all have a refractive index (n _d ) of 1.77 or more, more specifically 1.81 or more, and this refractive index (n _d ) of 2.20 or less. More specifically, it was 1.90 or less, and was within a desired range.

The optical glasses of the examples of the present invention all have an Abbe number (ν _d ) of 15 or more, more specifically 25 or more, and this Abbe number (ν _d ) of 30 or less, more specifically 28. And within the desired range.

  Moreover, as for the optical glass of the Example of this invention, milk white and devitrification were not recognized after the reheating test about what performed the reheating test. Therefore, it is presumed that the optical glasses of the examples of the present invention do not cause milky whiteness and devitrification after the reheating test.

Therefore, it is clear that the optical glass of the embodiment of the present invention is easy to perform mold press molding and has small chromatic aberration while the refractive index (n _d ) and Abbe number (ν _d ) are within the desired ranges. It was.

  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 (15)

The entire mass of the glass in terms of oxide composition, 10.0 to 40.0% of the SiO ₂ component in terms of mass%, and the Nb ₂ O ₅ component containing 26.358 40.0%, TiO ₂ component the content of 20.817% or less, ZrO ₂ component is 5.282~10%, Li ₂ O component is 1.0~10%, Na ₂ O component is 4.0~15%, Sb ₂ O ₃ component Is 0.5% or less, and the content of the K ₂ O component is 2.4% or less,
The mass ratio (TiO ₂ ) / (Nb ₂ O ₅ ) of the oxide equivalent composition is 0.15 or more and 0.79 or less ,
Mass sums for glass total weight of oxide composition in terms of _{(SiO 2 + P 2 O 5} + B 2 O 3 + GeO 2 + Li 2 O + Na 2 O + K 2 O + Cs 2 O) Mass sum _{(WO 3 + Nb 2 O 5} + TiO 2 + Ta 2 O 5 + Bi ₂ O ₃ + BaO) is 0.780 or more and less than 1.00,
It has an Abbe number (νd) of 15 to 30 and the partial dispersion ratio (θg, F) is normal when the partial dispersion ratio (θg, F) is between Abbe number (νd) and νd ≦ 25. It is higher than the line and satisfies the relationship of (θg, F) ≦ (−0.00480 × νd + 0.73500), and in the range of νd> 25, the partial dispersion ratio (θg, F) is higher than that of the normal line, An optical glass satisfying the relationship (θg, F) ≦ (−0.00250 × νd + 0.67750) and having a wavelength (λ70) of not more than 420 nm showing a spectral transmittance of 70% in a sample having a thickness of 10 mm. Ta ₂ O ₅ component 0 to 15.0% in mass% with respect to the total glass mass of oxide conversion composition,
WO ₃ component 0 to 25.0%,
Bi ₂ O ₃ component 0 to 25.0% and BaO component 0 to 20.0%
The optical glass according to claim 1, further comprising: _3. The optical glass according to claim 1, wherein a mass sum (WO ₃ + Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ + Bi ₂ O ₃ + BaO) with respect to the total glass mass of the oxide conversion composition is 65.0% or less. The entire mass of the glass in terms of oxide composition, B ₂ O ₃ component from 0 to 20.0% by mass%,
P ₂ O ₅ component from 0 to 10.0% and GeO ₂ component from 0 to 10.0%
The optical glass according to claim 1, further comprising: Cs ₂ O component 0 to 10.0 %
The optical glass according to claim 1 , further comprising: The mass sum of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, K, and Cs) with respect to the total glass mass of the oxide equivalent composition is 2.0% or more and 30.0% The optical glass according to claim 5, wherein: The mass sum (SiO ₂ + P ₂ O ₅ + B ₂ O ₃ + GeO ₂ + Li ₂ O + Na ₂ O + K ₂ O + Cs ₂ O) with respect to the total glass mass of the oxide conversion composition is less than 49.0%. The optical glass described. Y ₂ O ₃ component 0 to 10.0% in mass% with respect to the total glass mass of oxide conversion composition,
La ₂ O ₃ component 0 to 10.0%,
Gd ₂ O ₃ component 0 to 10.0%,
Yb ₂ O ₃ component 0 to 10.0% and Lu ₂ O ₃ component 0 to 10.0%
The optical glass according to claim 1, further comprising: The mass sum of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of Y, La, Gd, Yb and Lu) with respect to the total glass mass of the oxide equivalent composition is 15.0% or less The optical glass according to claim 8. The mass sum of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of Y, La, Gd, Yb and Lu) with respect to the total glass mass of the oxide equivalent composition is 8.5% or less. The optical glass according to claim 8. The mass ratio (TiO ₂ + Bi ₂ O ₃ ) / (WO ₃ + Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ + Bi ₂ O ₃ ) of the oxide equivalent composition is 0.80 or less. Optical glass. MgO component 0 to 20.0% in mass% with respect to the total glass mass of oxide conversion composition,
CaO component 0 to 20.0%,
SrO component 0-20.0% and ZnO component 0-20.0%
The optical glass according to claim 1, further comprising:   13. The mass sum of RO components (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) with respect to the total glass mass of the oxide equivalent composition is 25.0% or less. Optical glass. Al ₂ O ₃ component 0 to 10.0% in mass% with respect to the total glass mass of oxide conversion composition ,
T eO ₂ components from 0 to 10.0%, and CeO ₂ components from 0 to 10.0%
The optical glass according to claim 1, further comprising: A preform for polishing and / or precision press molding comprising the optical glass according to any one of claims 1 to 14.

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