JP6116859B2 - Optical glass, preform and optical element - Google Patents

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, it is expensive and low-efficiency to produce an aspheric lens by grinding or polishing methods. Therefore, as a method for manufacturing an aspheric lens, a preform material obtained by cutting and polishing a gob or a glass block is heated and softened. By pressing this with a mold having a highly accurate surface, the grinding / polishing process is omitted, and low-cost and mass production is realized.

Among optical glasses for producing optical elements, a high refractive index (n _d ) of 1.70 or more and a low Abbe number (ν _d ) of 25 or less, which are useful for reducing the weight and size of optical elements. There is a great demand for glass. As such a high refractive index and high dispersion glass, for example, glasses represented by Patent Documents 1 to 5 are known.

JP 2007-015904 A JP 2007-051060 A JP 2011-121831 A JP 2011-219278 A JP 2012-006787 A

  However, in the optical glasses described in Patent Documents 1 to 5, 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) By mass%, containing P ₂ O ₅ component of 7.0% or more and 30.0% or less, and Bi ₂ O ₃ component of 10.0% or more and 60.0% or less, and the maximum value of the linear expansion coefficient Optical glass whose (α _max ) is 1500 × 10 ⁻⁷ K ⁻¹ or less.

(2) The optical glass according to (1), wherein the Nb ₂ O ₅ component exceeds 0% and the TiO ₂ component exceeds 0% by mass%.

(3) The optical glass according to (1) or (2), wherein the content of Nb ₂ O ₅ component is 50.0% or less and the content of TiO ₂ component is 30.0% or less.

(4) The optical glass according to any one of (1) to (3), wherein the content of the WO ₃ component is 20.0% or less by mass.

(5) mass ratio _{WO 3 / (TiO 2 + Nb} 2 O 5) is 0.600 or less (1) to (4) any description of the optical glass.

(6) In mass%,
Li ₂ O component 0 to 10.0%
Na ₂ O component 0 to 15.0%
K ₂ O component 0 to 15.0%
The optical glass according to any one of (1) to (5).

(7) From (1) to (6), the sum of the contents of the Rn ₂ O component (Rn is one or more selected from the group consisting of Li, Na and K) is 20.0% or less by mass%. ) Any one of the optical glasses.

  (8) The optical glass according to any one of (1) to (7), wherein the content of the BaO component is 20.0% by mass or less.

(9) The optical glass according to any one of (1) to (8), wherein the GeO ₂ component content is 10.0% by mass or less.

(10) The optical glass according to any one of (1) to (9), wherein the content of the B ₂ O ₃ component is 10.0% or less by mass.

(11) 0 to 5.0% MgO component by mass%
CaO component 0 to 10.0%
SrO component 0 to 10.0%
The optical glass according to any one of (1) to (10).

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

(13) Y ₂ O ₃ component in mass% 0 to 10.0%
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%
The optical glass according to any one of (1) to (12).

(14) The sum of the contents of the Ln ₂ O ₃ component (Ln is at least one selected from the group consisting of Y, La, Gd and Yb) is 15.0% or less (1) to ( The optical glass according to any one of 13).

(15) SiO ₂ component by mass% 0 to 10.0%
ZnO component 0 to 10.0%
Al ₂ O ₃ component 0 to 10.0%
Ga ₂ O ₃ component from 0 to 10.0%
ZrO ₂ component 0 to 10.0%
Ta ₂ O ₅ component 0 to 10.0%
TeO ₂ component 0-15.0%
SnO component 0 to 10.0%
Sb ₂ O ₃ component 0-3.0%
The optical glass according to any one of (1) to (14).

(16) The optical glass according to any one of (1) to (15), which has a refractive index (n _d ) of 1.70 or more and 2.20 or less and an Abbe number (ν _d ) of 25 or less.

(17) The optical glass according to any one of (1) to (16), wherein a wavelength (λ ₇₀ ) exhibiting a spectral transmittance of 70% is 500 nm or less.

  (18) An optical element comprising the optical glass according to any one of (1) to (17).

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

  (20) An optical element obtained by precision pressing the preform described in (19).

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 7.0% to 30.0% of P ₂ O ₅ component and 10.0% to 60.0% of Bi ₂ O ₃ component in mass%, and linear expansion The maximum value (α _max ) of the coefficient is 1500 × 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 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 this specification, unless there is particular notice, content of each component shall be displayed by the mass% with respect to the glass total mass of an oxide conversion composition. Here, the "oxide equivalent composition" is assumed when the oxide, composite salt, metal fluoride, etc. used as the raw material of the glass constituent of the present invention are all decomposed and transformed 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 P ₂ O ₅ component is a glass forming component and is an essential component effective for enhancing the dispersion of glass. In particular, by containing 7.0% or more of the P ₂ O ₅ component, the maximum value of the linear expansion coefficient of the glass can be reduced, and the visible light transmittance of the glass can be increased. Therefore, the content of the P ₂ O ₅ component is preferably 7.0%, more preferably 9.0%, still more preferably 11.0%, still more preferably 13.0%, and even more preferably 15.0%. More preferably, the lower limit is 16.5%.
On the other _hand, when the content of P 2 _{O 5} component below 30.0%, suppressed the decrease in the refractive index. Therefore, the content of the P ₂ O ₅ component is preferably 30.0%, more preferably 25.0%, and still more preferably 20.0%.
The P ₂ O ₅ component can be contained in the glass using 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 Bi ₂ O ₃ component is an essential component that can reduce the Abbe number while increasing the refractive index of the glass. It is also a component that can lower the glass transition point. Therefore, the content of the Bi ₂ O ₃ component is preferably 10.0%, more preferably 14.0%, even more preferably 17.0%, still more preferably 20.0%, and even more preferably 23.0%. More preferably, the lower limit is 27.0%, more preferably 30.0%, and still more preferably 33.0%.
On the other hand, by the content of Bi ₂ O ₃ component below 60.0%, suppressed the degradation or devitrification of the visible light transmittance of the glass. Therefore, the content of the Bi ₂ O ₃ component is preferably 60.0%, more preferably 55.0%, still more preferably 50.0%, and further preferably 45.0%.
The Bi ₂ O ₃ component can be contained in the glass using Bi ₂ O ₃ or the like as a raw material.

The Nb ₂ O ₅ component is a component that can reduce the maximum value of the linear expansion coefficient of the glass, can lower the Abbe number while increasing the refractive index of the glass, and can improve the devitrification resistance of the glass. It is preferable to contain more than 0%. Therefore, the content of the Nb ₂ O ₅ component is preferably more than 0%, more preferably 5.0%, more preferably 10.0%, further preferably 13.0%, more preferably 17.0%, More preferably, the lower limit is 20.0%, more preferably 23.0%, and even more preferably 24.5%.
On the other hand, when the content of Nb ₂ O ₅ component is too large, the liquidus temperature of the glass devitrification resistance deteriorates increased. Therefore, the content of the Nb ₂ O ₅ component is preferably 50.0%, more preferably 40.0%, and still more preferably 35.0%.
The Nb ₂ O ₅ component can be contained in the glass using Nb ₂ O ₅ or the like as a raw material.

The TiO ₂ component is an effective component for reducing the maximum value of the linear expansion coefficient of glass, increasing the refractive index of the glass to lower the Abbe number, and improving devitrification resistance. It is preferable to make it contain super. Therefore, the content of the TiO ₂ component is preferably more than 0%, more preferably 0.5%, still more preferably 1.3%, and even more preferably 1.7%.
On the other hand, by setting the content of the TiO ₂ component to 30.0% or less, devitrification of the glass due to excessive inclusion of the TiO ₂ component can be suppressed, and the visible light transmittance of the glass can be increased. Therefore, the upper limit of the content of the TiO ₂ component is preferably 30.0%, more preferably 20.0%, still more preferably 10.0%, and even more preferably 4.5%.
TiO ₂ component can contain in the glass with TiO ₂ or the like as a raw material.

The WO ₃ component is an optional component that can increase the refractive index of the glass and lower the Abbe number when it contains more than 0%.
On the other hand, by setting the content of the WO ₃ component to 20.0% or less, the maximum value of the linear expansion coefficient of the glass can be reduced, the glass transition point can be lowered, and the visible light transmittance of the glass can be increased. Therefore, the content of the WO ₃ component is preferably 20.0%, more preferably 15.0%, more preferably less than 12.0%, still more preferably less than 10.0%.
The WO ₃ component can be contained in the glass using WO ₃ as a raw material.

The ratio (mass ratio) of the content of the WO ₃ component to the total amount of the Nb ₂ O ₅ component and the TiO ₂ component is preferably 0.600 or less. Thereby, among the components that can increase the refractive index of the glass and reduce the Abbe number, the total amount of the Nb ₂ O ₅ component and the TiO ₂ component that can reduce the maximum value of the linear expansion coefficient increases the maximum value of the linear expansion coefficient. Since it increases relative to the content of the WO ₃ component, an optical glass having a smaller maximum value of linear expansion coefficient can be obtained while obtaining a high refractive index and high dispersion. Therefore, the upper limit of the mass ratio (WO ₃ / (Nb ₂ O ₅ + TiO ₂ )) is preferably 0.600, more preferably 0.500, still more preferably 0.400, and still more preferably 0.340.

Li ₂ O component, Na ₂ O component and _{K 2} O component, when ultra containing 0%, the glass transition point can be lowered, and an optional component that enhances devitrification resistance.
On the other hand, by making the content of the Li ₂ O component 10.0% or less and / or by making the content of the Na ₂ O component 15.0% or less, the maximum value of the linear expansion coefficient of the glass , The decrease in the refractive index of the glass can be suppressed, and devitrification due to excessive inclusion of the Li ₂ O component and the Na ₂ O component can be reduced. Further, by the content of K 2 _O component below 15.0%, it suppressed the decrease in the refractive index of the glass, and can reduce the devitrification due to excessive content of K 2 _O component.
Therefore, the upper limit of the content of the Li ₂ O component is preferably 10.0%, more preferably 5.0%, still more preferably 2.5%, and still more preferably 2.0%. The content of each of the Na ₂ O component and the K ₂ O component is preferably 15.0%, more preferably 10.0%, still more preferably 4.0%, and even more preferably 2.5%. And
Li ₂ O component, Na ₂ O component, and K ₂ O component are Li ₂ CO ₃ , LiNO ₃ , LiF, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ , K ₂ CO ₃ , KNO ₃ as raw materials. , KF, KHF ₂ , K ₂ SiF _{6 and the} like can be contained in the glass.

The total amount (mass sum) of Rn ₂ O components (wherein Rn is one or more selected from the group consisting of Li, Na and K) is preferably 20.0% or less. Thus, due to excessive content of Rn 2 _O component, increase and the maximum value of the linear expansion coefficient of the glass, lowering of the refractive index, it is suppressed deterioration of devitrification resistance. Therefore, the total amount of the Rn ₂ O component is preferably 20.0%, more preferably 10.0%, still more preferably 8.0%, still more preferably 6.5%, still more preferably 5.5%, More preferably, the upper limit is 4.5%.

The BaO component is an optional component that can increase the refractive index and devitrification resistance of the glass and can hardly reduce the visible light transmittance when it is contained in an amount of more than 0%. Therefore, the content of the BaO component is preferably more than 0%, more preferably more than 0.5%, still more preferably more than 0.8%, and even more preferably more than 1.1%.
On the other hand, when the content of the BaO component is 20.0% or less, an increase in the Abbe number can be suppressed, and a decrease in devitrification resistance and chemical durability can be suppressed. Accordingly, the upper limit of the BaO component content is preferably 20.0%, more preferably 10.0%, and even more preferably 6.0%.
The BaO component can be contained in the glass using, for example, BaCO ₃ , Ba (NO ₃ ) ₂ , BaF ₂ or the like as a raw material.

The GeO ₂ component is an optional component that can enhance the refractive index and devitrification resistance of the glass when it is contained in excess of 0%.
On the other hand, by making the content of the GeO ₂ component 10.0% or less, the use of expensive GeO ₂ component is reduced, so that the material cost of the glass can be reduced. Therefore, the content of the GeO ₂ component is preferably 10.0% as an upper limit, more preferably less than 5.0%, and still more preferably less than 3.0%.
The GeO ₂ component can be contained in the glass using GeO ₂ or the like as a raw material.

When the B ₂ O ₃ component is contained in an amount of more than 0%, the B ₂ O ₃ component is an optional component that can reduce the maximum value of the linear expansion coefficient of the glass and increase the devitrification resistance of the glass. Accordingly, the content of the B ₂ O ₃ component is preferably more than 0%, more preferably 0.5%, and even more preferably 0.6%.
On the other hand, by making the content of B ₂ O ₃ component to 10.0% or less, it is suppressed the decrease in the refractive index and the visible light transmittance. Therefore, the content of the B ₂ O ₃ component is preferably 10.0%, more preferably 5.0%, still more preferably 3.0%, and still more preferably 1.9%.
B ₂ O ₃ component can contain _H 3 _BO 3 as a starting _{material, Na 2 B 4 O 7,} Na 2 B 4 O 7 · 10H 2 O, with BPO ₄ or the like in the glass.

The MgO component, CaO component and SrO component are optional components that can enhance the devitrification resistance of the glass when they are contained in excess of 0%.
On the other hand, when the content of the MgO component is 5.0% or less and / or the content of each of the CaO component and SrO component is 10.0% or less, the refractive index of the glass is decreased. It is possible to suppress the increase in Abbe number and to suppress the devitrification of the glass due to excessive inclusion of these components. Therefore, the content of the MgO component is preferably 5.0%, more preferably 3.0%, and still more preferably 1.0%. The content of each of the CaO component and the SrO component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.
The MgO component, CaO component, and SrO component can be contained in the glass using MgCO ₃ , MgF ₂ , CaCO ₃ , CaF ₂ , Sr (NO ₃ ) ₂ , SrF _2, etc. as raw materials.

The total amount (mass sum) of RO components (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba and Zn) is preferably 20.0%. Thereby, the raise and devitrification of the Abbe number of glass by excessive inclusion of RO component can be suppressed. Therefore, the total amount of RO components is preferably 20.0%, more preferably 10.0%, and even more preferably 7.0%.
On the other hand, when the RO component contains more than 0% in total, the devitrification resistance of the glass can be further improved. Therefore, the total amount of RO components is preferably more than 0%, more preferably 0.5%, and even more preferably 1.0%.

When Y ₂ O ₃ component, La ₂ O ₃ component, Gd ₂ O ₃ component and Yb ₂ O ₃ component are contained over 0%, the refractive index of the glass can be increased, and the chemical durability of the glass is increased. Optional ingredients.
On the other hand, by setting the content of each of these components to 10.0% or less, it is possible to suppress an increase in the Abbe number and reduce glass devitrification due to excessive inclusion of these components. Therefore, the content of each of the Y ₂ O ₃ component, the La ₂ O ₃ component, the Gd ₂ O ₃ component, the Yb ₂ O ₃ component, and the Lu ₂ O ₃ component is preferably 10.0%, more preferably 5. The upper limit is 0%, more preferably 3.0%.
Y ₂ O ₃ component, La ₂ O ₃ component, Gd ₂ O ₃ component and Yb ₂ O ₃ component are Y ₂ O ₃ , YF ₃ , La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ O as raw materials. (X is an arbitrary integer), Gd ₂ O ₃ , GdF ₃ , Yb ₂ O _{3 and the} like can be used for inclusion in the glass.

The total amount (mass sum) of Ln ₂ O ₃ components (wherein Ln is one or more selected from the group consisting of Y, La, Gd and Yb) is preferably 15.0% or less. Thereby, the raise of Abbe number and the devitrification of glass can be suppressed. Therefore, the total amount of the Ln ₂ O ₃ components is preferably 15.0%, more preferably 10.0%, still more preferably 5.0%, and even more preferably 3.0%.

When the SiO ₂ component is contained in an amount of more than 0%, it is an optional component that can reduce the coloring of the glass to increase the visible light transmittance and increase the devitrification resistance of the glass.
On the other hand, when the content of SiO ₂ component to 10.0% or less, is suppressed a decrease in the refractive index. Accordingly, the upper limit of the content of the SiO ₂ component is preferably 10.0%, more preferably 5.0%, and even more preferably 3.0%.
SiO ₂ component can contain in the glass with _{SiO 2, K 2 SiF 6,} Na 2 SiF 6 , etc. as a raw material.

The ZnO component is an optional component that can enhance the devitrification resistance of the glass when it contains more than 0%.
On the other hand, by setting the content of the ZnO component to 10.0% or less, devitrification due to a decrease in the refractive index of the glass, an increase in the Abbe number, and excessive inclusion of the ZnO component can be suppressed. Therefore, the content of the ZnO component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.
The ZnO component can be contained in the glass using ZnO, ZnF ₂ or the like as a raw material.

The Al ₂ O ₃ component and the Ga ₂ O ₃ component are optional components that can increase the chemical durability of the glass and increase the viscosity at the time of melting the glass when the content is more than 0%.
On the other hand, the deterioration of the devitrification resistance of the glass can be suppressed by setting the contents of the Al ₂ O ₃ component and the Ga ₂ O ₃ component to 10.0% or less, respectively. 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%, and still more preferably 3.0%.
The Al ₂ O ₃ component and the Ga ₂ O ₃ component can be contained in the glass using Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ , Ga ₂ O ₃ , Ga (OH) ₃ or the like as raw materials.

The ZrO ₂ component is an optional component that increases the visible light transmittance of the glass and increases the devitrification resistance of the glass when it contains more than 0%.
On the other hand, by setting the content of the ZrO ₂ component to 10.0% or less, a decrease in refractive index and devitrification due to an excessive content of the ZrO ₂ component can be suppressed. Therefore, the content of the ZrO ₂ component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.
The ZrO ₂ component can be contained in the glass using ZrO ₂ , ZrF ₄ or the like as a raw material.

The Ta ₂ O ₅ component is an optional component that can increase the refractive index of the glass when it exceeds 0%.
On the other hand, by making the content of _Ta 2 _{O 5} component to 10.0% or less, enhanced resistance to devitrification of the glass. Therefore, the content of the Ta ₂ O ₅ component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.
The Ta ₂ O ₅ component can be contained in the glass using Ta ₂ O ₅ or the like as a raw material.

The TeO ₂ component is an optional component that can increase the refractive index of the glass and lower the glass transition point when it contains more than 0%.
On the other hand, the visible light transmittance of the glass can be increased by setting the content of the TeO ₂ component to 15.0% or less. Therefore, the content of the TeO ₂ component is preferably 15.0%, more preferably 10.0%, further preferably 5.0%, and further preferably 3.0%.
The TeO ₂ component can be contained in the glass using TeO ₂ or the like as a raw material.

The SnO component is an optional component that can lower the glass transition point and increase the visible light transmittance when it is contained in excess of 0%.
On the other hand, by setting the content of the SnO component to 10.0% or less, the devitrification resistance of the glass can be hardly lowered. Further, it is possible to suppress the coloring of the glass and the decrease in the visible light transmittance caused by the dissolution of the melting equipment (especially a noble metal such as Pt). Therefore, the content of the SnO component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.
SnO ingredients, for example _SnO, can be contained in the glass raw material with SnO 2, SnO ₃ and the like.

The Sb ₂ O ₃ component is an optional component that, when contained in excess of 0%, can increase the visible light transmittance of the glass and can be degassed when the glass is melted.
On the other hand, by making the content of the Sb ₂ O ₃ component 3.0% or less, the Sb ₂ O ₃ component becomes difficult to be alloyed with the melting equipment (especially a noble metal such as Pt), and thus adheres to the mold. Since impurities are reduced, the formation of irregularities and cloudiness on the surface of the glass molded body can be reduced, and the life of the mold can be extended. Further, by setting the content of _Sb 2 _{O 3} component to 3.0% or less, it can be reduced solarization of the glass. Therefore, the content of the Sb ₂ O ₃ component is preferably 3.0%, more preferably 1.0%, and still more preferably 0.5%.
Sb ₂ O ₃ component, as a raw material by using _{Sb 2 O 3, Sb 2 O} 5, Na 2 H 2 Sb 2 O 7 · 5H 2 O or the like can be contained in the glass.

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

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

  If necessary, other components can be added to the optical glass of the present invention as long as the properties of the glass of the present invention are not impaired.

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

  Furthermore, lead compounds such as PbO and components of Th, Cd, Tl, Os, Be, and Se tend to refrain from being used as harmful chemical substances in recent years. In addition, measures for environmental measures are required until disposal after commercialization. Therefore, when importance is placed on the environmental impact, it is preferable not to substantially contain them except for inevitable mixing. As a result, the optical glass is substantially free of substances that pollute the environment. Therefore, the optical glass can be manufactured, processed, and discarded without taking special environmental measures.

The glass composition of the present invention cannot be expressed directly in the description of mol% because the composition is expressed by mass% with respect to the total mass of the glass of oxide conversion composition, but various properties required in the present invention. The composition expressed by mol% of each component present in the glass composition satisfying the above conditions generally takes the following values in terms of oxide conversion.
P ₂ O ₅ component from 10.0 to 45.0 mol%,
Nb ₂ O ₅ component 8.0 to 40.0 mol% and Bi ₂ O ₃ component 4.0 to 25.0 mol%
TiO ₂ component 0 to 60.0 mol%,
WO ₃ component 0-20.0 mol%,
Li ₂ O component from 0 to 60.0 mol%,
Na ₂ O component from 0 to 50.0 mol%,
K ₂ O component from 0 to 30.0 mol%,
BaO component 0 to 30.0 mol%,
GeO ₂ component 0-20.0 mol%,
B ₂ O ₃ component 0 to 30.0 mol%,
MgO component 0 to 25.0 mol%,
CaO component 0-35.0 mol%,
SrO component 0 to 20.0 mol%,
Y ₂ O ₃ component 0 to 10.0 mol%,
La ₂ O ₃ component from 0 to 8.0 mol%,
Gd ₂ O ₃ component 0 to 7.0 mol%,
Yb ₂ O ₃ component from 0 to 6.0 mol%,
SiO ₂ component 0 to 30.0 mol%,
ZnO component 0 to 30.0 mol%,
Al ₂ O ₃ component 0 to 20.0 mol%,
Ga ₂ O ₃ component 0 to 10.0 mol%,
ZrO ₂ component 0 to 15.0 mol%
Ta ₂ O ₅ component 0-5.0 mol%,
TeO ₂ component 0-25.0 mol%,
SnO component 0 to 15.0 mol%
Sb ₂ O ₃ component 0 to 2.5 mol%

[Production method]
The optical glass of the present invention is produced, for example, as follows. That is, the above raw materials are uniformly mixed so that each component is within a predetermined content range, and the prepared mixture is put into a quartz crucible or an alumina crucible and roughly melted, and then a platinum crucible, a platinum alloy crucible or iridium Put in a crucible and melt in the temperature range of 1000 to 1250 ° C for 2 to 10 hours, stir to homogenize and blow out bubbles, etc., then lower the temperature to 1200 ° C or lower and then stir to finish to remove striae It is produced by casting into a mold and slow cooling.

[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 1500 × 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 1500 × 10 ⁻⁷ K. ^-1 , More preferably 1200 × 10 ⁻⁷ K ⁻¹ , More preferably 1000 × 10 ⁻⁷ K ⁻¹¹ , More preferably 900 × 10 ⁻⁷ K ⁻¹¹ , More preferably 800 × 10 ⁻⁷ K ⁻¹¹ And On the other hand, the lower limit of the maximum value (α _max ) of this linear expansion coefficient is preferably 100 × 10 ⁻⁷ K ⁻¹ , more preferably 200 × 10 ⁻⁷ K ⁻¹ , and even more preferably 300 × 10 ⁻⁷ K. ^It is good also as ^-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 25, more preferably 23, and still more preferably 20. The lower limit of this Abbe number may be preferably 15, more preferably 16, and still 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.
The refractive index (n _d ) of the optical glass of the present invention is preferably 1.70, more preferably 1.80, still more preferably 1.85, still more preferably 1.89, still more preferably 1.92. More preferably, the lower limit is 1.95, more preferably 1.99. The upper limit of this refractive index is preferably 2.20, more preferably 2.15, and even more preferably 2.10. 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 430 nm, and even more preferably 410 nm. 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 490 nm, and still more preferably 480 nm. 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 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 ), spectral transmittance of 70% and 5% of Examples (No. 1 to No. 7) and Comparative Example (No. A) of the present invention. Table 1 shows the wavelength (λ ₇₀ , λ ₅ ) and the maximum value (α _max ) of the linear expansion coefficient. 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 material to be selected is weighed so as to have the composition ratios of the examples and comparative examples shown in the table, and mixed uniformly, and then put into a platinum crucible, depending on the melting difficulty of the glass composition. Melt in an electric furnace at a temperature range of 1000 to 1250 ° C. for 2 to 10 hours, stir and homogenize, blow out bubbles, etc. The glass was produced by cooling.

Here, the refractive index and Abbe number of the glass of the Examples and Comparative Examples were measured according to Japan Optical Glass Industry Society Standard JOGIS01- ^2003. 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.

Also, 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%).

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 Table 1, in the optical glasses of the examples of the present invention, stable glass is obtained, and the temperature range 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 was 1500 × 10 ⁻⁷ K ⁻¹ or less, more specifically 800 × 10 ⁻⁷ K ⁻¹ or less, which 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 optical glass of 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 1.70 or more, more specifically 1.99 or more, while this refractive index (n _d ) is 2.20 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 25 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 480 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 5% transmittance) was 450 nm or less, more specifically 410 nm or less, and was in a desired range.

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 (13)

% By mass
7.0% or more and 25.0% or less of P ₂ O ₅ component,
Bi ₂ O ₃ component 23.0% or more and 50.0% or less,
Nb ₂ O ₅ component is 17.0% or more and 40.0% or less,
TiO ₂ component is 0.5% to 4.5%,
BaO component more than 0.5% 10.0% or less, and B ₂ O ₃ component contains 0.5% or more and 10.0% or less,
WO ₃ component content is less than 12.0%,
The content of the Li ₂ O component is 10.0% or less,
The content of Na ₂ O component is 10.0% or less,
The content of K ₂ O component is 10.0% or less,
And
It has a refractive index (n _d ) of 1.70 or more and 2.20 or less, and has an Abbe number (ν _d ) of 25 or less ( excluding those whose refractive index (n _d ) exceeds 2.05) ,
Optical glass whose maximum value (α _max ) of linear expansion coefficient between the glass transition point (Tg) and the yield point (At) is 1500 × 10 ⁻⁷ K ⁻¹ or less. The optical glass according to claim 1, wherein a mass ratio WO ₃ / (TiO ₂ + Nb ₂ O ₅ ) is 0.600 or less. 3. The optical glass according to claim 1, wherein the content of the Rn ₂ O component (Rn is at least one selected from the group consisting of Li, Na, and K) in mass% is 20.0% or less. . The optical glass according to any one of claims 1 to 3, wherein the content of the GeO ₂ component is 10.0% or less by mass. MgO component 0% to 5.0% by mass
CaO component 0 to 10.0%
SrO component 0 to 10.0%
The optical glass according to any one of claims 1 to 4.   The optical component according to any one of claims 1 to 5, wherein the total content of RO components (R is at least one selected from the group consisting of Mg, Ca, Sr and Ba) is 20.0% or less. Glass. Y ₂ O ₃ component in mass% 0 to 10.0%
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%
The optical glass according to any one of claims 1 to 6. The sum of the contents of Ln ₂ O ₃ components (Ln is at least one selected from the group consisting of Y, La, Gd and Yb) is 15.0% or less. The optical glass described. SiO ₂ component in mass% 0 to 10.0%
ZnO component 0 to 10.0%
Al ₂ O ₃ component 0 to 10.0%
Ga ₂ O ₃ component from 0 to 10.0%
ZrO ₂ component 0 to 10.0%
Ta ₂ O ₅ component 0 to 10.0%
TeO ₂ component 0 to 10.0%
SnO component 0 to 10.0%
Sb ₂ O ₃ component 0-3.0%
The optical glass according to any one of claims 1 to 8. Wavelength spectral transmittance indicates _70% (λ 70) is 500nm or less, optical glass according to any of claims 1 to 9. An optical element formed of the optical glass according to any of claims 1 10. For grinding claims 1 formed of the optical glass according to any one of the 10 and / or precision press preform for molding. An optical element comprising the preform according to claim 12 .