JP2014111521A - Optical glass, preform, and optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical glass capable of reducing breakage or cracks of glass during press-forming while having a desired high refractive index (n) and a low Abbe number (ν), and thereby, capable of increasing productivity of an optical element, and to provide a preform and an optical element using the optical glass.SOLUTION: The optical glass comprises, expressed in terms of mass%, 50.0 to 90.0% of a BiOcomponent and 5.0 to 50.0% of a BOcomponent, and has a coefficient of linear expansion of 1600×10Kor less at the maximum (α). The preform and the optical element are made of the optical glass.

Description

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

  In recent years, the digitization and high definition of devices that use optical systems have been rapidly progressing, and the precision of optical elements such as lenses used in various optical devices, including photography devices such as digital cameras and video cameras, The demand for light weight and downsizing is increasing.

  In particular, optical design using an aspheric lens is effective to reduce the weight and size of the optical system, but it is not productive to produce an aspheric lens by grinding or polishing. Therefore, it is possible to soften the preform material by cutting and polishing the gob and glass block by heating, and by performing precision press molding by pressing with a mold with a high-precision surface, the grinding and polishing process is performed. Omitted, realizing low cost and mass production.

Among optical glasses for producing optical elements, particularly, it has a high refractive index ( _nd ) of 1.90 or more and 2.30 or less, which is effective for reducing the weight and size of the optical element, and is 30 or less. The demand for glasses with low Abbe numbers (ν _d ) is very high. As a glass having a high refractive index and a low Abbe number, for example, glasses represented by Patent Documents 1 to 4 are known.

JP 2011-093731 A JP 2006-327926 A JP 2011-051886 A JP 2009-203140 A

  However, in the optical glasses described in Patent Documents 1 to 4, many glass cracks and cracks occurred when press molding was performed. Here, glass in which cracks or cracks have occurred after press molding can no longer be used as an optical element. Therefore, development of optical glass reduced in cracks and cracks during press molding is desired.

The present invention has been made in view of the above-described problems, and the object thereof is to provide a desired high refractive index (n _d ) and low Abbe number (ν _d ), but at the time of press molding. It is an object of the present invention to provide an optical glass capable of reducing the cracks and cracks in the glass and thereby improving the productivity of the optical element, and a preform and an optical element using the optical glass.

  The present inventors have intensively studied to solve the above problems, and have completed the present invention. Specifically, the present invention provides the following.

(1) It contains 50.0 to 90.0% Bi ₂ O ₃ component and 5.0 to 50.0% B ₂ O ₃ component in mass%, and the maximum value of linear expansion coefficient (α _max ) is Optical glass which is 1600 × 10 ⁻⁷ K ⁻¹ or less.

(2) The optical glass according to (1), which contains, by mass%, a SiO ₂ component exceeding 0%.

(3) The optical glass according to (1) or (2), wherein the content of the SiO ₂ component is 20.0% or less by mass.

(4) The optical glass according to any one of (1) to (3), in which the sum of the contents of the B ₂ O ₃ component and the SiO ₂ component is 5.0% or more and 55.0% or less.

(5) the weight ratio _{(SiO 2 / B 2 O 3} ) is 0.01 or more (1) to (4) the optical glass according to any one of.

(6) The optical glass according to any one of (1) to (5), wherein the mass ratio Bi ₂ O ₃ / (SiO ₂ + B ₂ O ₃ ) is 15.00 or less.

(7) Li ₂ O component in mass% 0 to 10.0%
Na ₂ O component 0 to 20.0%
K ₂ O component 0 to 20.0%
The optical glass according to any one of (1) to (6).

(8) Any of (1) to (7), wherein the mass sum of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) is 20.0% or less The optical glass described.

(9) The optical glass according to any one of (1) to (8), wherein a mass ratio Rn ₂ O / (SiO ₂ + B ₂ O ₃ ) is 0.300 or less.

(10) The optical glass according to any one of (1) to (9), wherein the content of the TeO ₂ component is 30.0% by mass or less.

(11) MgO component in mass% 0 to 10.0%
CaO component 0 to 10.0%
SrO component 0 to 10.0%
BaO component 0 to 10.0%
ZnO component 0 to 20.0%
The optical glass according to any one of (1) to (10).

  (12) The mass sum of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba, Zn) is 20.0% or less, from (1) to (11) Any one of the optical glasses.

(13) The optical glass according to any one of (1) to (12), wherein the mass ratio (RO + Rn ₂ O) / (SiO ₂ + B ₂ O ₃ ) is 0.600 or less.

(14) La ₂ O ₃ component in mass% 0 to 10.0%
Gd ₂ O ₃ component 0 to 10.0%
Y ₂ O ₃ component 0 to 10.0%
Yb ₂ O ₃ component 0 to 10.0%
The optical glass according to any one of (1) to (13).

(15) The total content of Ln ₂ O ₃ components (wherein Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) in mass% is 20.0% or less ( The optical glass according to any one of 1) to (14).

(16)% by weight _P 2 _{O 5} component from 0 to 15.0%
GeO ₂ component 0-20.0%
Al ₂ O ₃ component 0 to 10.0%
Ga ₂ O ₃ component from 0 to 10.0%
Ta ₂ O ₅ component 0 to 10.0%
TiO ₂ component 0 to 10.0%
Nb ₂ O ₅ component 0 to 10.0%
WO ₃ component 0-15.0%
ZrO ₂ component 0 to 15.0%
SnO ₂ component 0-3.0%
Sb ₂ O ₃ component 0-3.0%
The optical glass according to any one of (1) to (15).

(17) By mass%, SiO ₂ component, ZrO ₂ component, Nb ₂ O ₅ component, ZnO component, MgO component, CaO component, SrO component, BaO component, Li ₂ O component, Na ₂ O component and K ₂ O component The optical glass according to any one of (1) to (16), wherein the sum of the contents of is at least 1.0%.

  (18) The optical glass according to any one of (1) to (17), wherein the refractive index (nd) is 1.90 or more and 2.30 or less, and the Abbe number (νd) is 14 or more and 30 or less.

(19) The optical glass according to any one of (1) to (18), wherein a wavelength (λ ₇₀ ) having a spectral transmittance of 70% is 500 nm or less.

  (20) An optical element comprising the optical glass according to any one of (1) to (19).

  (21) A preform for polishing and / or precision press molding comprising the optical glass according to any one of (1) to (19).

  (22) An optical element obtained by precision pressing the preform described in (21).

According to the present invention, while having a high refractive index (n _d ) and a low Abbe number (ν _d ), it is possible to reduce glass cracks and cracks during press molding, thereby improving the productivity of optical elements. A possible optical glass, a preform and an optical element using the optical glass can be provided.

The optical glass of the present invention contains 50.0 to 90.0% of Bi ₂ O ₃ component and 5.0 to 50.0% of B ₂ O ₃ component in mass%, and has a maximum linear expansion coefficient ( α _max ) is 1600 × 10 ⁻⁷ K ⁻¹ or less. As a result, even if the desired high refractive index and low Abbe number are obtained, even if the glass is heated to a temperature higher than the glass transition point and subjected to press molding, the glass after press molding becomes difficult to break and cracks also occur. It becomes difficult. Therefore, while reducing the thickness and weight of the optical element, it is possible to reduce the glass that is cracked or cracked in the step of pressing the glass, particularly in the optical element manufacturing process, thereby increasing the productivity of the optical element. be able to.

  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 can be implemented with appropriate modifications within the scope of the object of the present invention. . 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. Unless otherwise specified in the present specification, the contents of the respective components are all 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 a raw material of the glass component of the present invention are all decomposed and changed into an oxide 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 Bi ₂ O ₃ component is an essential component that can increase the refractive index of the glass to lower the Abbe number and lower the glass transition point. In particular, by containing 50.0% or more of the Bi ₂ O ₃ component, it is possible to easily obtain a glass having a high refractive index and a low Abbe number and a low glass transition point. Therefore, the content of the Bi ₂ O ₃ component is preferably 50.0%, more preferably 60.0%, and still more preferably 71.0%.
On the other hand, by setting the content of the Bi ₂ O ₃ component to 90.0% or less, the devitrification resistance of the glass can be enhanced, and the coloring of the glass by the Bi ₂ O ₃ component can be reduced to transmit visible light. The wavelength can be increased (in particular, the wavelength (λ ₅ ) at which the spectral transmittance is 5% can be shortened). Therefore, the content of the Bi ₂ O ₃ component is preferably 90.0%, more preferably 88.0%, and still more preferably 85.0%.
As the Bi ₂ O ₃ component, Bi ₂ O ₃ or the like can be used as a raw material.

The B ₂ O ₃ component is a glass forming component and an essential component that increases the devitrification resistance of the glass. That is, by making the content of the B ₂ O ₃ component 5.0% or more, the maximum value of the linear expansion coefficient of the glass is lowered, the devitrification resistance is increased, and the visible light transmittance is increased (especially The wavelength (λ ₅ ) at which the spectral transmittance is 5% can be shortened). Therefore, the content of the B ₂ O ₃ component is preferably 5.0%, more preferably 6.0%, even more preferably 8.0%, still more preferably 10.0%, and even more preferably 11.0%. Is the lower limit.
On the other hand, when the content of B ₂ O ₃ component is too large, easily devitrified rather lower devitrification resistance of the glass. Also, the Abbe number tends to increase. Therefore, the content of the B ₂ O ₃ component is preferably 50.0%, more preferably 40.0%, further preferably 30.0%, and further preferably 20.0%.
As the B ₂ O ₃ component, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ .10H ₂ O, BPO ₄ or the like can be used as a raw material.

The SiO ₂ component is an optional component that can enhance the devitrification resistance of the glass and increase the visible light transmittance when it contains more than 0%. Therefore, the content of the SiO ₂ component is preferably more than 0%, more preferably 0.8%, and still more preferably 1.3%.
On the other hand, when the content of SiO ₂ component to 10.0% or less, is suppressed a decrease in the refractive index. Therefore, the upper limit of the content of the SiO ₂ component is preferably 20.0%, more preferably 10.0%, still more preferably 7.0%, still more preferably 4.0%, and even more preferably 3.0%. And
As the SiO ₂ component, SiO ₂ or the like can be used as a raw material, but can also be added to the glass by using a quartz crucible for melting the glass material.

The sum of the contents of the B ₂ O ₃ component and the SiO ₂ component is preferably 5.0% or more and 55.0% or less.
In particular, by making this sum 5.0% or more, the maximum value of the linear expansion coefficient of the glass can be lowered, the devitrification resistance of the glass can be increased, and the visible light transmittance of the glass can be increased. Therefore, the mass sum (SiO ₂ + B ₂ O ₃ ) is preferably 5.0%, more preferably 8.0%, still more preferably 10.0%, still more preferably 11.0%, and still more preferably 13. The lower limit is 0%, more preferably 13.6%.
On the other hand, by making this sum 55.0% or less, an increase in press temperature can be suppressed by suppressing an increase in glass transition point. Moreover, the fall of the refractive index of glass by these components can be suppressed. Accordingly, the upper limit of the mass sum (SiO ₂ + B ₂ O ₃ ) is preferably 55.0%, more preferably 35.0%, still more preferably 25.0%, and further preferably 19.0%.

The ratio (mass ratio) of the content of the SiO ₂ component to the content of the B ₂ O ₃ component is preferably 0.01 or more. By increasing this ratio, the maximum value of the linear expansion coefficient of the glass can be lowered as compared with the case where no SiO ₂ component is contained. Therefore, the mass ratio (SiO ₂ / B ₂ O ₃ ) is preferably 0.01, more preferably 0.05, and still more preferably 0.07.
On the other hand, the upper limit of this ratio is preferably 1.00, more preferably 0.65, still more preferably 0.35, and even more preferably 0.25, from the viewpoint of lowering the glass transition point. Good.

The ratio (mass ratio) of the content of Bi ₂ O ₃ component to the sum of the content of SiO ₂ component and B ₂ O ₃ component is preferably 15.00 or less. Thereby, the maximum value of the linear expansion coefficient of glass can be made low. In addition, this makes it possible to increase the visible light transmittance of the glass (especially shorten the wavelength (λ ₇₀ ) at which the spectral transmittance is 70%). Accordingly, the mass ratio (Bi ₂ O ₃ / B ₂ O ₃ ) is preferably 15.00, more preferably 11.00, even more preferably 8.00, still more preferably 6.00, and even more preferably 5.86. Is the upper limit.
On the other hand, this ratio is preferably 1.50, more preferably 2.50, more preferably 3.50, and still more preferably from the viewpoint of lowering the glass Abbe number and lowering the glass transition point. 4.30 may be the lower limit.

Li 2 _O component, Na 2 _O component and K _{2 O} component, when 0% ultra-containing, adjust the refractive index of the glass and the Abbe number, which is an optional component and can be lowered glass transition temperature.
On the other hand, by setting the content of these components to a predetermined value or less, a decrease in the refractive index of the glass and an increase in the Abbe number can be suppressed. Therefore, the content of the Li ₂ O component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%. The content of each of the Na ₂ O component and the K ₂ O component is preferably 20.0%, more preferably 10.0%, still more preferably 5.0%, still more preferably 3.0%. And
As the Li ₂ O component, Na ₂ O component, and K ₂ O component, Li ₂ CO ₃ , LiNO ₃ , Na ₂ CO ₃ , NaNO ₃ , K ₂ CO ₃ , KNO _{3 and the} like can be used as raw materials.

The total content (mass sum) of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na and K) is preferably 20.0% or less. Thereby, the fall of the refractive index of glass and the raise of an Abbe number can be suppressed. Further, the devitrification resistance of the glass is also improved. Therefore, the mass sum (Li ₂ O + Na ₂ O + K ₂ O) is preferably 20.0%, more preferably 10.0%, still more preferably 5.0%, still more preferably 2.5%, still more preferably 1. The upper limit is 23%.

The TeO ₂ component is an optional component that increases the devitrification resistance of the glass and promotes the defoaming and clarification of the glass melt when it contains more than 0%. Further, by containing the TeO ₂ component, the visible light transmittance can be increased without largely changing the refractive index and the Abbe number. Therefore, the content of the TeO ₂ component may be the mass% based on the oxide, preferably more than 0%, more preferably 0.1%, and further preferably 0.3%.
On the other hand, if the content of the TeO ₂ component is too large, the glass tends to devitrify, and the maximum value of the linear expansion coefficient tends to increase. Therefore, the content of the TeO ₂ component is preferably 30.0%, more preferably 15.0%, still more preferably 10.0%, and still more preferably 4.0%.
TeO ₂ component can use TeO ₂ or the like as a raw material.

The MgO component, CaO component, SrO component, and BaO component are optional components that enhance the devitrification resistance of the glass when contained in excess of 0%.
However, when there is too much content of these components, it will become easy to devitrify on the contrary. Therefore, the content of each of the MgO component, CaO component, SrO component and BaO component is preferably 10.0%, more preferably 5.0%, and even more preferably 3.0%.
As the MgO component, CaO component, SrO component, and BaO component, MgO, MgCO ₃ , CaCO ₃ , Sr (NO ₃ ) ₂ , BaCO ₃ , Ba (NO ₃ ) ₂ or the like can be used as a raw material.

When the ZnO component is contained in an amount of more than 0%, it is possible to increase the devitrification resistance of the glass and increase the visible light transmittance (in particular, the wavelength (λ ₇₀ ) at which the spectral transmittance is 70% can be shortened). It is an ingredient. Therefore, the content of the ZnO component is preferably more than 0%, more preferably 0.5%, even more preferably 0.7%, and even more preferably 1.0%.
However, when the content of the ZnO component is too large, devitrification tends to occur and the Abbe number increases. Accordingly, the upper limit of the content of the ZnO component is preferably 20.0%, more preferably 10.0%, and even more preferably 5.0%.
As the ZnO component, ZnO or the like can be used as a raw material.

The total content (mass sum) of RO components (R is one or more selected from Mg, Ca, Sr, Ba, and Zn) is preferably 20.0% or less. Thereby, devitrification due to excessive inclusion of these components can be reduced. Therefore, the total content of RO components is preferably 20.0%, more preferably 15.0%, still more preferably 10.0%, and still more preferably 7.0%.
In addition, the devitrification resistance of glass can be improved by containing RO component more than 0% in total. Therefore, the content of the RO component is preferably more than 0%, more preferably 0.5%, and still more preferably 1.0%.

The ratio (mass ratio) of the sum of the contents of the RO component and the Rn ₂ O component to the sum of the contents of the SiO ₂ component and the B ₂ O ₃ component is preferably 0.600 or less. As a result, among components that have a small contribution to high refractive index and high dispersion and a large contribution to the stability (devitrification resistance) of glass, RO components that do not act to lower the maximum value of the linear expansion coefficient, Since the content of the Rn ₂ O component is relatively reduced, a glass having a smaller maximum linear expansion coefficient can be obtained. Accordingly, the mass ratio (RO + Rn ₂ O) / (SiO ₂ + B ₂ O ₃ ) is preferably 0.600, more preferably 0.500, and still more preferably 0.410.
On the other hand, this mass ratio is preferably 0.010, more preferably 0.030, still more preferably 0.070, and even more preferably 0.100, from the viewpoint of further improving the devitrification resistance of the glass. Good.

Further, to the sum of the content of SiO ₂ component and _B 2 _{O 3} component, the ratio of the content of Rn ₂ O component (mass ratio) is preferably 0.300 or less. As a result, the content of the Rn ₂ O component that easily increases the maximum value of the linear expansion coefficient among components that do not act to decrease the maximum value of the linear expansion coefficient is relatively reduced, so that the maximum value of the linear expansion coefficient is further increased. Of small glass. Therefore, the mass ratio Rn ₂ O / (SiO ₂ + B ₂ O ₃ ) is preferably 0.300, more preferably 0.200, more preferably less than 0.120, still more preferably less than 0.100, More preferably, it is less than 0.080.

A La ₂ O ₃ component, a Gd ₂ O ₃ component, a Y ₂ O ₃ component, and a Yb ₂ O ₃ component are optional components that can increase the liquidus temperature of the glass when contained in excess of 0%.
On the other hand, an increase in the Abbe number can be suppressed by setting the content of each of these components to 10.0% or less. Accordingly, the content of each of the La ₂ O ₃ component, Gd ₂ O ₃ component, Y ₂ O ₃ component and Yb ₂ O ₃ is preferably 10.0%, more preferably 5.0%, and even more preferably 3. The upper limit is 0%.
La ₂ O ₃ component, Gd ₂ O ₃ component, Y ₂ O ₃ component and Yb ₂ O ₃ component are La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ O (X is an arbitrary integer), Gd ₂ O ₃ , Y ₂ O ₃ , Yb ₂ O ₃ or the like can be used.

The sum (mass sum) of the contents of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y and Yb) is preferably 20.0% or less. Thereby, the increase in Abbe number by these components can be suppressed. Accordingly, the sum of the contents of the Ln ₂ O ₃ component is preferably 20.0%, more preferably 10.0%, still more preferably 5.0%, and even more preferably 1.5%.

P ₂ O ₅ component, when ultra containing 0%, which is an optional component that can improve the visible light transmittance of the glass.
On the other hand, by making the content of the P ₂ O ₅ component 15.0% or less, the glass material can be easily dissolved and the devitrification resistance of the glass can be improved. Therefore, the content of the P ₂ O ₅ component is preferably 15.0%, more preferably 8.0%, still more preferably 4.0%, and still more preferably 2.0%.
As the P ₂ O ₅ component, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , Na (PO ₃ ), BPO ₄ , H ₃ PO _{4 and the} like can be used as raw materials.

The GeO ₂ component is an optional component that can improve the devitrification resistance of the glass when it exceeds 0%.
On the other hand, when the content of GeO ₂ component is too large, it tends to decrease. Meltability, and raw material cost of the glass increases greatly. Therefore, the content of the GeO ₂ component is preferably 20.0%, more preferably 10.0%, still more preferably 5.0%, and still more preferably 3.0%.
As the GeO ₂ component, GeO ₂ or the like can be used as a raw material.

The Al ₂ O ₃ component and the Ga ₂ O ₃ component are optional components that can improve the chemical durability and mechanical strength of the glass when contained in excess of 0%.
On the other hand, the content of each of _Al 2 _{O 3} component and _Ga 2 _{O 3} component by 10.0% or less, can be easily dissolved a glass material. In particular, the devitrification resistance of the glass can be increased by reducing the content of the Al ₂ O ₃ component. Therefore, the content of each of the Al ₂ O ₃ component and the Ga ₂ O ₃ component is preferably 10.0%, more preferably 5.0%, still more preferably 3.0%, and even more preferably 1%. Less than 0%.
As the Al ₂ O ₃ component and Ga ₂ O ₃ component, Al ₂ O ₃ , Al (OH) ₃ , Ga ₂ O ₃ , Ga (OH) _3, or the like can be used as a raw material.

The Ta ₂ O ₅ component is an optional component that can enhance the devitrification resistance of the glass while suppressing an increase in the Abbe number of the glass when it contains more than 0%.
However, if the content of the Ta ₂ O ₅ component is too large, the glass tends to be devitrified, the glass transition point is increased, and the glass raw material cost is significantly increased. Therefore, the content of the Ta ₂ O ₅ component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.
As the Ta ₂ O ₅ component, Ta ₂ O ₅ or the like can be used as a raw material.

The TiO ₂ component is an optional component that can reduce the Abbe number of the glass when it contains more than 0%.
On the other hand, by making the content of the TiO ₂ component 10.0% or less, the devitrification resistance of the glass is increased, and the decrease in the visible light transmittance of the glass can be suppressed. Therefore, the content of the TiO ₂ component is preferably 10.0%, more preferably 5.0%, still more preferably 3.0%, and still more preferably 1.0%.
As the TiO ₂ component, TiO ₂ or the like can be used as a raw material.

Nb ₂ O ₅ component, when 0% ultra-containing, is an optional component that can reduce the Abbe number of the glass.
On the other hand, by setting the content of the Nb ₂ O ₅ component to 10.0% or less, the devitrification resistance of the glass can be increased, and an increase in the glass transition point can be suppressed. Therefore, the content of the Nb ₂ O ₅ component is preferably 10.0%, more preferably 5.0%, still more preferably 3.0%, and still more preferably 1.0%.
As the Nb ₂ O ₅ component, Nb ₂ O ₅ or the like can be used as a raw material.

WO ₃ component is an optional component that can reduce the Abbe number of the glass, increase the devitrification resistance of the glass, and lower the glass transition point when it contains more than 0%.
However, when the content of WO ₃ component is too large, the glass tends rather devitrification, visible light transmittance of the glass decreases. Therefore, the upper limit of the content of the WO ₃ component is preferably 15.0%, more preferably 10.0%, and still more preferably 5.0%.
As the WO ₃ component, WO ₃ or the like can be used as a raw material.

The ZrO ₂ component is an optional component that can increase the devitrification resistance of the glass and improve the chemical durability and mechanical strength of the glass when it contains more than 0%.
However, when the content of the ZrO ₂ component is too large, the glass tends to devitrify and the glass transition point becomes high. Therefore, the content of the ZrO ₂ component is preferably 15.0%, more preferably 10.0%, still more preferably 5.0%, still more preferably 3.0%, and even more preferably 1.0%. And
As the ZrO ₂ component, ZrO ₂ or the like can be used as a raw material.

The SnO ₂ component is an optional component that can increase the chemical durability of the glass when it exceeds 0%.
However, when the content of SnO ₂ component is too large, solubility of the glass material becomes difficult, the visible light transmittance of the glass decreases. Therefore, the content of the SnO ₂ component is preferably 3.0%, more preferably 2.0%, and still more preferably 1.0%.
As the SnO ₂ component, SnO ₂ , SnO, or the like can be used as a raw material.

The Sb ₂ O ₃ component is an optional component that promotes defoaming and clarification of the glass melt when it exceeds 0%.
On the other hand, when Sb ₂ O ₃ content is too high, the visible light transmittance of the glass decreases. Therefore, the content of the Sb ₂ O ₃ component is preferably 3.0%, more preferably 1.0%, and still more preferably 0.3%.
As the Sb ₂ O ₃ component, Sb ₂ O ₃ , Sb ₂ O ₅ , Na ₂ H ₂ Sb ₂ O ₇ .5H ₂ O, or the like can be used as a raw material.

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

Sum of contents of SiO ₂ component, ZrO ₂ component, Nb ₂ O ₅ component, ZnO component, MgO component, CaO component, SrO component, BaO component, Li ₂ O component, Na ₂ O component and K ₂ O component (mass) Is preferably 1.0% or more. Thereby, the devitrification resistance of glass can be improved. Therefore, the mass sum (SiO ₂ + ZrO ₂ + Nb ₂ O ₅ + ZnO + MgO + CaO + SrO + BaO + Li ₂ O + Na ₂ O + K ₂ O) is preferably 1.0%, more preferably 2.0%, and still more preferably 3.0%.
On the other hand, the desired high refractive index and low Abbe number can be easily obtained by setting the mass sum to 30.0% or less. Therefore, the mass sum (SiO ₂ + ZrO ₂ + Nb ₂ O ₅ + ZnO + MgO + CaO + SrO + BaO + Li ₂ O + Na ₂ O + K ₂ O) is preferably 30.0%, more preferably 20.0%, still more preferably 11.0%, still more preferably 8 .8% is the upper limit.

<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.

  Other components not described above can be added as necessary within a range not impairing the properties of the glass of the present invention. However, each transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag and Mo, excluding Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, is independent of each other. Or even if it is contained in a small amount in combination, the glass is colored, and absorption occurs at a specific wavelength in the visible range, so that the effect of increasing the visible light transmittance of the present invention is diminished. It is preferable that the optical glass that transmits the light does not substantially contain.

Moreover, since lead compounds such as PbO and arsenic compounds such as As ₂ O ₃ are components with high environmental loads, it is desirable that they are not substantially contained, that is, not contained at all except for inevitable mixing.

  Furthermore, each component of Th, Cd, Tl, Os, Be, and Se has tended to refrain from being used as a harmful chemical material in recent years. When used, not only the glass manufacturing process, but also the processing process, and It is necessary to take measures for environmental measures until disposal after commercialization. Therefore, when importance is placed on the environmental impact, it is preferable that these are not substantially contained.

The glass composition of the present invention cannot be expressed directly in the description of mol% because the composition is expressed by mass% with respect to the total mass of the glass of oxide conversion composition, but various properties required in the present invention. The composition expressed by mol% of each component present in the glass composition satisfying the above conditions generally takes the following values in terms of oxide conversion.
Bi ₂ O ₃ component from 20.0 to 60.0 mol% and _B 2 _{O 3} component from 12.0 to 70.0 mol%
And SiO ₂ component 0 to 40.0 mol%
Li ₂ O component 0 to 50.0 mol%
Na ₂ O component from 0 to 40.0 mol%
K ₂ O component from 0 to 30.0 mol%
TeO ₂ component 0 to 30.0 mol%
MgO component 0-40.0 mol%
CaO component 0-35.0 mol%
SrO component 0 to 30.0 mol%
BaO component 0 to 20.0 mol%
ZnO component 0 to 40.0 mol%
La ₂ O ₃ component from 0 to 7.0 mol%
Gd ₂ O ₃ component 0 to 7.0 mol%
Y ₂ O ₃ component 0-5.0 mol%
Yb ₂ O ₃ component from 0 to 7.0 mol%
P ₂ O ₅ component from 0 to 30.0 mol%
GeO ₂ component 0-30.0 mol%
Al ₂ O ₃ component 0 to 20.0 mol%
Ga ₂ O ₃ component 0 to 10.0 mol%
Ta ₂ O ₅ component 0-8.0 mol%
TiO ₂ component 0 to 20.0 mol%
Nb ₂ O ₅ component 0 to 7.0 mol%
WO ₃ components 0 to 15.0 mol%
ZrO ₂ component 0 to 30.0 mol%
SnO ₂ component 0 to 15.0 mol%
Sb ₂ O ₃ component from 0 to 7.0 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 in a quartz crucible or a gold crucible and melted in a temperature range of 750 to 1000 ° C. for 2 to 3 hours. The mixture is stirred and homogenized, and after about 1 hour has passed since the temperature is lowered to about 850 to 650 ° C., the mixture is cast into a mold and gradually cooled.

<Physical properties>
In the optical glass of the present invention, the maximum value (α _max ) of the linear expansion coefficient in the temperature range between the glass transition point (Tg) and the yield point (At) is 1600 × 10 ⁻⁷ K ⁻¹ or less. As a result, even when a thin optical element with a high refractive index is produced, the glass is difficult to break when heated to a temperature higher than the glass transition point and subjected to press molding. Can be increased. The reason why the glass is difficult to break in this manner is, for example, when the glass is heated and softened, or when the softened glass is press-molded and cooled, due to the temperature difference inside the glass, the linear expansion coefficient is increased inside the glass. When it is divided into a high-temperature part above the large glass transition point and a low-temperature part below the glass transition point with a small linear expansion coefficient, the thermal expansion and heat shrinkage of the high-temperature part is reduced by reducing the thermal expansion and heat shrinkage of the high-temperature part. This reduces the force applied to the low temperature part.
Therefore, in the optical glass of the present invention, the upper limit of the maximum value (α _max ) of the linear expansion coefficient in the temperature range between the glass transition point (Tg) and the yield point (At) is preferably 1600 × 10 ⁻⁷ K. ⁻¹ , more preferably 1500 × 10 ⁻⁷ K ⁻¹ , and even more preferably 1400 × 10 ⁻⁷ K ⁻¹¹ . On the other hand, the lower limit of the maximum value (α _max ) of this linear expansion coefficient is preferably 500 × 10 ⁻⁷ K ⁻¹ , more preferably 600 × 10 ⁻⁷ K ⁻¹ , and even more preferably 700 × 10 ⁻⁷ K. ^It may be ^-1 .
In this specification, the maximum value of the linear expansion coefficient in the temperature range between the glass transition point (Tg) and the yield point (At) may be simply referred to as “the maximum value of the linear expansion coefficient”.

The optical glass of the present invention preferably has higher dispersion (low Abbe number) while having a high refractive index.
The upper limit of the Abbe number (ν _d ) of the optical glass of the present invention is preferably 30, more preferably 25, still more preferably 23, and still more preferably 20. The lower limit of this Abbe number may preferably be 14, more preferably 16, and even more preferably 17. By having such a low Abbe number, for example, when combined with an optical element having a high Abbe number, high imaging characteristics and the like can be achieved.
Further, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.90, more preferably 1.91, still more preferably 1.95, and still more preferably 2.00. The upper limit of this refractive index is preferably 2.30, more preferably 2.25, and even more preferably 2.20. By having such a high refractive index, a large amount of light can be obtained even if the device is further thinned.
Therefore, by using such an optical glass having a high refractive index and high dispersion, for example, for an optical element, the degree of freedom in optical design can be expanded while achieving high imaging characteristics and the like.

It is preferable that the optical glass of the present invention has high visible light transmittance, in particular, high light transmittance on the short wavelength side of visible light, and little coloring. In particular, in the optical glass of the present invention, the shortest wavelength (λ ₅ ) exhibiting a spectral transmittance of 5% in a sample having a thickness of 10 mm is preferably 450 nm, more preferably 440 nm, still more preferably 420 nm, and even more preferably 415 nm. And In the optical glass of the present invention, the shortest wavelength (λ ₇₀ ) showing a spectral transmittance of 70% in a sample having a thickness of 10 mm is preferably 500 nm, more preferably 480 nm, still more preferably 460 nm, further preferably 455 nm. And As a result, the absorption edge of the glass is positioned in the ultraviolet region or in the vicinity thereof, and the transparency of the glass with respect to light on the short wavelength side in the visible region is further enhanced, so that the glass is colored yellow or orange. Therefore, the optical glass can be preferably used as a material for an optical element that transmits visible light such as a lens.

  The optical glass of the present invention preferably has a glass transition point of 450 ° C. or lower. Thereby, since glass softens at lower temperature, glass can be press-molded at lower temperature. Further, it is possible to extend the life of the mold by reducing oxidation of the mold used for mold press molding. Therefore, the upper limit of the glass transition point of the optical glass of the present invention is preferably 450 ° C., more preferably 440 ° C., and further preferably 430 ° C. The lower limit of the glass transition point of the optical glass of the present invention is not particularly limited, but the glass transition point of the optical glass of the present invention is preferably 100 ° C, more preferably 200 ° C, and even more preferably 300 ° C. Good.

The optical glass of the present invention preferably has a small average coefficient of linear expansion (α). In particular, the average linear expansion coefficient of the optical glass of the present invention is preferably 130 × 10 ⁻⁷ K ⁻¹ , more preferably 120 × 10 ⁻⁷ K ⁻¹ , and most preferably 110 × 10 ⁻⁷ K ⁻¹ . It is good. Thereby, when optical glass is press-molded with a mold, the total amount of expansion and contraction due to temperature change of the glass is reduced. Therefore, the optical glass can be made more difficult to break during press molding.

The optical glass of the present invention may be an optical glass having a large partial dispersion ratio. That is, in the optical glass of the present invention, the partial dispersion ratio (θg, F) is 0.63 or more, or the relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) is (θg, F)> − 0.0108 × (ν _d ) +0.8500 may be an optical glass having an optical performance within a range where the formula is satisfied. By using such an optical glass, an optical glass having a large partial dispersion ratio (θg, F) can be obtained. Therefore, the optical glass is useful for reducing chromatic aberration of an optical element.
Here, the partial dispersion ratio (θg, F) is preferably 0.630, more preferably 0.635, and still more preferably 0.640.
The relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) is preferably (θg, F)> − 0.0108 × [νd] +0.8500, more preferably (θg, F)>. −0.0108 × (ν _d ) +0.8510, more preferably (θg, F)> − 0.0108 × (ν _d ) +0.8520 may be satisfied.

  The optical glass of the present invention preferably has high devitrification resistance during glass production (in the specification, it may be simply referred to as “devitrification resistance”). Thereby, since the fall of the transmittance | permeability by crystallization of the glass at the time of glass preparation etc. is suppressed, this optical glass can be used preferably for the optical element which permeate | transmits visible lights, such as a lens.

[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 was prepared from optical glass, and after performing reheat press molding on this preform, polishing was performed to prepare a glass molded body, or polishing was performed. It is possible to produce a glass molded body by performing precision press molding on a preform, or a preform molded by a known floating molding or the like. In addition, the means for producing the glass molded body is not limited to these means.

  The glass molded body produced in this way is useful for various optical elements and optical designs. In particular, it is preferable to produce optical elements such as lenses, prisms, and mirrors from the optical glass of the present invention using means such as precision press molding. As a result, when used in optical devices that transmit visible light to optical elements such as cameras and projectors, the optical system in these optical devices is miniaturized while realizing high-definition and high-precision imaging characteristics. Can be achieved.

Composition (refractive index (n _d ), Abbe number (ν _d ), partial dispersion ratio (θg, F) of glass of Examples (No. 1 to No. 13) and Comparative Example (No. A) of the present invention, Table 1 and Table 1 show the wavelengths (λ ₇₀ , λ ₅ ), the glass transition point (Tg), the average linear expansion coefficient (α), and the maximum linear expansion coefficient (α _max ) at which the spectral transmittance is 70% and 5%. It is shown in 2. The following examples are merely for illustrative purposes, and are not limited to these examples.

  The glass of these Examples and Comparative Examples are used for ordinary optical glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, metaphosphate compounds, etc., as raw materials for each component. The high-purity raw materials to be selected are selected and weighed so that the glass weight is 400 g with the compositions of the examples and comparative examples shown in the table, and then mixed uniformly, and then put into a gold crucible to melt the glass composition Depending on the degree of difficulty, it was melted in an electric furnace in a temperature range of 750 ° C. to 1000 ° C. for 2 to 3 hours, stirred and homogenized to remove bubbles, and then the temperature was lowered to 850 to 650 ° C. for about 1 hour. Then, glass was produced by casting in a metal mold and gradually cooling.

Here, the refractive index of the glass of the Examples and Comparative Examples, the Abbe number and the partial dispersion ratio were measured according to Japan Optical Glass Industry Society Standard JOGIS01- ^2003. Then, regarding the obtained Abbe number and partial dispersion ratio, the intercept b when the slope a is 0.0108 in the relational expression (θg, F) = − a × ν _d + b was obtained. In addition, as glass used for this measurement, what was processed with the annealing furnace on the annealing conditions of slow cooling fall rate -25 degrees C / hr was used.

Further, the visible light transmittance of the glass of the Examples and Comparative Examples were measured according to Japan Optical Glass Industry Society Standard JOGIS02- ^2003. In addition, in this invention, the presence or absence and the grade of coloring of glass were calculated | required by measuring the visible light transmittance | permeability of glass. More specifically, a face parallel polished product having a thickness of 10 ± 0.1 mm is measured for a spectral transmittance of 200 to 800 nm in accordance with JISZ8722, and λ ₅ (wavelength when the transmittance is 5%) and λ ₇₀ (transmittance). Wavelength at 70%).

  Moreover, the glass transition point (Tg) of the glass of an Example and a comparative example was calculated | required by performing the measurement using a differential-heat measuring apparatus (STAC409CD by a Netchgeretebau company) in nitrogen atmosphere. Here, the sample particle size at the time of measurement was 425 to 600 μm, and the temperature was increased from 100 ° C. to 800 ° C. at a temperature increase rate of 5 ° C./min.

The average linear expansion coefficient of the optical glass of the Examples and Comparative Examples, in accordance with the Japanese Optical Glass Industrial Standard JOGIS08- ²⁰⁰³ "method of measuring thermal expansion of optical glass", an average linear expansion coefficient at -30 to + 70 ° C. It was.

The maximum value (alpha _max) of the linear expansion coefficient of the glass of the Examples and Comparative Examples were measured according to Japan Optical Glass Industry Society Standard JOGIS08- ²⁰⁰³ "method of measuring thermal expansion of optical glass", glass transition temperature (Tg ) To the yield point (At), the maximum value of the linear expansion coefficient in increments of 5 ° C. was determined. For the calculation of the linear expansion coefficient, the length of the sample at a temperature of a multiple of 5 was used.

As shown in Tables 1 and 2, in the optical glasses of the examples of the present invention, both stable glasses are obtained, and between the glass transition point (Tg) and the yield point (At). The upper limit of the maximum value (α _max ) of the linear expansion coefficient in the temperature range of 1600 × 10 ⁻⁷ K ⁻¹ or less, more specifically 1510 × 10 ⁻⁷ K ⁻¹ or less, was within the desired range. . On the other hand, in the comparative example of Table 1, it was devitrified and stable glass was not obtained. For this reason, in the Example of this invention, it became clear that the stable optical glass with a small maximum value ((alpha) _max ) of a linear expansion coefficient can be obtained.

The optical glasses of the examples of the present invention all have a refractive index (n _d ) of 1.90 or more, more specifically 2.00 or more, while this refractive index (n _d ) is 2.30 or less. As such, it has been found that it has the desired high refractive index (n _d ).

The optical glasses of the examples of the present invention all had an Abbe number (ν _d ) of 30 or less, more specifically 20 or less. For this reason, it became clear that the optical glass of the Example of this invention has a low Abbe number ((nu) _d ).

All of the optical glasses of the examples of the present invention had a λ ₇₀ (wavelength at a transmittance of 70%) of 500 nm or less, more specifically, 460 nm or less, and were within a desired range.
In addition, in all the optical glasses of the examples of the present invention, λ ₅ (wavelength at a transmittance of 5%) was 450 nm or less, more specifically 420 nm or less, and was in a desired range.

  Since the optical glass of the example of the present invention has a glass transition point of 450 ° C. or lower, more specifically, 430 ° C. or lower, it was revealed that the optical glass has a desired low glass transition point.

Since the optical glass of the example of the present invention has an average linear expansion coefficient of 130 × 10 ⁻⁷ K ⁻¹ or less, more specifically 110 × 10 ⁻⁷ K ⁻¹ or less, a desired low average linear expansion coefficient is obtained. It became clear to have.

Therefore, the optical glass of the example of the present invention has a low Abbe number (ν _d ) while having a desired high refractive index (n _d ), and a high transmittance for visible light. And the maximum value (α _max ) of the linear expansion coefficient was found to be small.

Furthermore, the optical glass of the example of the present invention was press-molded and processed into the shape of a lens or a prism. As a result, it was revealed that when the optical glass of the example was press-molded, the smaller the maximum value of the linear expansion coefficient (α _max ), the less likely the glass was to be cracked. Therefore, since the optical glass of the Example of this invention has the small maximum value of a linear expansion coefficient, it is guessed that it is hard to produce a crack in the glass after press molding.

  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 (22)

It contains 50.0 to 90.0% of Bi ₂ O ₃ component and 5.0 to 50.0% of B ₂ O ₃ component in mass%, and the maximum value of linear expansion coefficient (α _max ) is 1600 × 10 Optical glass that is ⁻⁷ K− ¹ or less. In mass%, the optical glass according to claim 1, wherein the SiO ₂ component contains more than 0%. The optical glass according to claim 1 or 2, wherein the content of the SiO ₂ component is 20.0% or less in terms of mass%. The optical glass according to any one of claims 1 to 3, wherein the sum of the contents of the B ₂ O ₃ component and the SiO ₂ component is 5.0% or more and 55.0% or less in terms of mass%. The optical glass according to claim 1, wherein a mass ratio (SiO ₂ / B ₂ O ₃ ) is 0.01 or more. The optical glass according to claim 1, wherein a mass ratio Bi ₂ O ₃ / (SiO ₂ + B ₂ O ₃ ) is 15.00 or less. Li ₂ O component in mass% 0 to 10.0%
Na ₂ O component 0 to 20.0%
K ₂ O component 0 to 20.0%
The optical glass according to any one of claims 1 to 6. 8. The optical glass according to claim 1, wherein the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) has a mass sum of 20.0% or less. The optical glass according to claim 1, wherein a mass ratio Rn ₂ O / (SiO ₂ + B ₂ O ₃ ) is 0.300 or less. The optical glass according to any one of claims 1 to 9, wherein the content of the TeO ₂ component is 30.0% or less in terms of mass%. MgO component in mass% 0 to 10.0%
CaO component 0 to 10.0%
SrO component 0 to 10.0%
BaO component 0 to 10.0%
ZnO component 0 to 20.0%
The optical glass according to any one of claims 1 to 10.   The optical component according to any one of claims 1 to 11, wherein the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba, Zn) is 20.0% or less. Glass. The optical glass according to claim 1, wherein a mass ratio (RO + Rn ₂ O) / (SiO ₂ + B ₂ O ₃ ) is 0.600 or less. La ₂ O ₃ component in mass% 0 to 10.0%
Gd ₂ O ₃ component 0 to 10.0%
Y ₂ O ₃ component 0 to 10.0%
Yb ₂ O ₃ component 0 to 10.0%
The optical glass according to any one of claims 1 to 13. The sum of the contents of Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, Yb) in mass% is 20.0% or less. 14. The optical glass according to any one of 14. _P 2 _{O 5} component from 0 to 15.0% by mass%
GeO ₂ component 0-20.0%
Al ₂ O ₃ component 0 to 10.0%
Ga ₂ O ₃ component from 0 to 10.0%
Ta ₂ O ₅ component 0 to 10.0%
TiO ₂ component 0 to 10.0%
Nb ₂ O ₅ component 0 to 10.0%
WO ₃ component 0-15.0%
ZrO ₂ component 0 to 15.0%
SnO ₂ component 0-3.0%
Sb ₂ O ₃ component 0-3.0%
The optical glass according to any one of claims 1 to 15. Content of SiO ₂ component, ZrO ₂ component, Nb ₂ O ₅ component, ZnO component, MgO component, CaO component, SrO component, BaO component, Li ₂ O component, Na ₂ O component and K ₂ O component by mass% The optical glass according to any one of claims 1 to 16, wherein the sum is 1.0% or more.   The optical glass according to any one of claims 1 to 17, wherein a refractive index (nd) is 1.90 or more and 2.30 or less, and an Abbe number (νd) is 14 or more and 30 or less. The optical glass according to claim 1, wherein the wavelength (λ ₇₀ ) at which the spectral transmittance is 70% is 500 nm or less.   An optical element made of the optical glass according to claim 1.   A preform for polishing and / or precision press molding comprising the optical glass according to any one of claims 1 to 19.   An optical element obtained by precision pressing the preform according to claim 21.