CN107082562B

CN107082562B - Optical glass, optical element, and preform for precision press molding

Info

Publication number: CN107082562B
Application number: CN201610959882.3A
Authority: CN
Inventors: 土渊菜那; 荻野道子
Original assignee: Ohara Inc
Current assignee: Ohara Inc
Priority date: 2009-04-30
Filing date: 2010-04-30
Publication date: 2021-02-09
Anticipated expiration: 2030-04-30
Also published as: CN107082562A; WO2010126141A1; KR20120004538A; CN102159512A; KR101657245B1

Abstract

The invention provides not only refractive index (n)_d) In the desired range and has a low Abbe number (v)_d) And optical glass, optical element and preform for precision press molding having high transparency to visible light. The optical glass contains 5.0-40.0% by mass of P in terms of oxide of the total mass of the glass₂O₅Component (B) containing 10.0 to 60.0% of Nb₂O₅And (3) components. The optical element and the preform for precision press molding are made of the optical glass.

Description

Optical glass, optical element, and preform for precision press molding

The present application is a divisional application with an application date of 2010 at 4 and 30 (a chinese national stage date of 2011 at 3 and 15), a national stage application number of 201080002608.8, and an invention name of "optical glass, optical element, and preform for precision press molding".

Technical Field

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

Background

In recent years, with the rapid progress of digitalization and high definition of instruments using optical systems, demands for high precision, light weight, and miniaturization of optical elements such as lenses used in optical systems, as typified by image pickup devices such as digital cameras and video cameras, have been increasing.

In the optical glass for manufacturing the optical element, the optical element can be particularly lightened and miniaturized, and has a high refractive index (n) of more than 1.70 and less than 2.20_d) And has an Abbe number (v) of 10 to 25_d) Glasses with high refractive index and high dispersion are very demanding. The high-refractive-index, high-dispersion glass is, for example, a glass having a refractive index (n)_d) An optical glass having an abbe number of 1.91 or more and 21 or less is known, and a glass represented by patent document 1 is known. And as a refractive index (n)_d) An optical glass having an abbe number of 1.65 or more and 17.2 or more and 33.1 or less, and a glass represented by patent document 2 is known.

Patent document 1: japanese patent laid-open publication No. 2005-206433

Patent document 2: japanese patent laid-open publication No. H06-345481

Disclosure of Invention

When an optical element is produced using such a glass, the following method can be used: a method of heating and softening a glass material, press-molding the glass material (reheating and press-molding) to obtain a glass molded article (formed glass), and grinding and polishing the glass molded article; a method (precision press molding) of heating and softening a preform material, which is obtained by grinding and polishing a cut glass gob (gob) or glass block (block), or a preform material molded by a known float molding or the like, and press-molding the preform material in a mold having a high-precision molding surface.

However, the glass disclosed in patent document 1 has an Abbe number (v)_d) The lower the transparency to visible light (λ)₇₀Is large) and Abbe number (v)_d) Low glass will be tinted yellow or orange. Therefore, even if the glass disclosed in patent document 1 has a desired high dispersion, the use of transmitting visible light cannot be realized.

Further, the glasses disclosed in patent documents 1 and 2 have a problem that devitrification easily occurs at the time of manufacturing the glass. Further, glass in which devitrification does not occur at the time of manufacturing glass has the following problems: when a glass press-molded by reheating and pressing is subjected to polishing or when a glass is subjected to polishing to produce a preform, cloudiness is likely to occur. In particular, when devitrification or clouding occurs, it is difficult to produce an optical element capable of controlling visible light from the glass.

Further, many of the glasses disclosed in patent documents 1 and 2 are glasses that are difficult to polish and press-mold. Specifically, when a glass molded article after press molding is polished to obtain an optical element, or when a glass gob or a glass block is polished, glass is easily damaged. When the glass is heated in a mold and press-molded to form the glass into the shape of an optical element or a preform thereof, indentation or crack is often generated in the glass.

Further, since many of the glasses disclosed in patent documents 1 and 2 have a high glass transition point (Tg), they are not easily softened even when they are heated. Therefore, if the preform material is made of the glass of patent document 1 and the preform material is heated and softened and press-molded to manufacture the optical element, the temperature of the preform material to be heated and softened and press-molded needs to be increased, which may cause the mold for press-molding to melt and adhere to the preform material or affect the optical characteristics of the optical element.

Further, the glasses disclosed in patent documents 1 and 2 have the following problems: for example, when glass press-molded by reheating and pressurizing is polished and then washed, or when glass is polished and then washed to produce a preform, turbidity is likely to occur. In particular, when devitrification or clouding occurs, it is difficult to produce an optical element capable of controlling visible light from the glass.

The present invention has been made in view of the above problems, and an object thereof is to provide a refractive index (n)_d) In the desired range and having a low Abbe number (v)_d) And an optical glass and an optical element having high transparency to visible light.

Further, the present invention has an object to provide a light-emitting element having the above refractive index (n)_d) Abbe number (v)_d) And transparency to visible light, and also hardly causes devitrification or clouding in the production and processing of the glass, and also allows easy production of a preform material and an optical element by a polishing process.

Further, the present invention has an object to provide a light-emitting element having the above refractive index (n)_d) Abbe number (v)_d) And an optical glass and an optical element which are transparent to visible light and are easily subjected to polishing and press molding.

Further, the present invention has an object to provide a light-emitting element having the above refractive index (n)_d) Abbe number (v)_d) And optical glass, optical element and preform for precision press molding which are transparent to visible light and are easily softened at low temperature.

It is also an object of the present invention to provide a lens having the above refractive index(n_d) Abbe number (v)_d) And optical glass and optical elements which are transparent to visible light and easily washed when producing preformed materials and optical elements.

The inventors have made extensive and intensive studies to solve the above problems and as a result, have found that the content of P in a specific amount₂O₅Component (B) and Nb₂O₅The present inventors have found that the above-mentioned glass composition can provide a glass having a high refractive index, a high dispersion, a low Abbe number, and a high transparency to visible light, and have completed the present invention.

Further, the present inventors have found that P is contained in a specific amount₂O₅Component (B) and Nb₂O₅Component (b) can increase the refractive index (n)_d) Dispersion and transparency to visible light, while the liquidus temperature of the glass is lowered, and acid resistance can be improved.

Furthermore, the present inventors have found that by containing a specific amount of P₂O₅Component (B) and Nb₂O₅Component (b) can increase the refractive index (n)_d) Dispersion and transparency to visible light while imparting a suitable degree of abrasion, and the average linear expansion coefficient (α) becomes small.

Furthermore, the present inventors have also found that P is used in combination₂O₅Component (B) and Nb₂O₅And P is₂O₅Component (B) and Nb₂O₅Component (B) and TiO₂The refractive index (n) can be increased by controlling the content of the component in a specific range_d) Dispersion and transparency to visible light, while the glass transition point (Tg) is reduced.

Furthermore, the present inventors have also found that P is used in combination₂O₅Component (B) and Nb₂O₅Component (C) and contains Li₂O component and Na₂Component O and K₂At least one of the O components is an essential component, and the refractive index (n) can be increased_d) Dispersion and transparency to visible light, while the glass transition point (Tg) becomes low.

Furthermore, the present inventors have found that by containing a specific amount of P₂O₅Composition (I)And Nb₂O₅Component (b) can increase the refractive index (n)_d) Dispersion and transparency to visible light, while increasing the liquidus temperature and increasing the detergent resistance of the glass. Specifically, the present invention provides the following.

(1) An optical glass containing 5.0 to 40.0% by mass of P in terms of oxide of the total mass of the glass₂O₅Component (b), 10.0% to 60.0% Nb₂O₅And (3) components.

(2) The optical glass according to (1), which has a spectral transmittance of 70% at a wavelength (. lamda.) of₇₀) Is 500nm or less, and has a liquidus temperature of 500 to 1200 ℃.

(3) The optical glass according to (1), which has an abrasion degree of 100 or more and 400 or less.

(4) The optical glass according to (1), which has a detergent resistance (PR) of grade 1 to 3 according to ISO test method.

(5) The optical glass as described in (1), which contains Li₂O component and Na₂Component O and K₂At least one of the O components has a glass transition point (Tg) of 700 ℃ or lower as an essential component.

(6) The optical glass as described in any one of (1) to (5), wherein TiO is contained in mass% with respect to the total mass of the glass in terms of oxide of the composition₂The content of the component is below 30.0%.

(7) The optical glass as described in (6), wherein TiO is contained in an amount of mass% based on the total mass of the glass in terms of oxide of the composition₂The content of the component is less than 12.0%.

(8) The optical glass as described in (6), wherein TiO is contained in an amount of mass% based on the total mass of the glass in terms of oxide of the composition₂The content of the components is less than 10.0%.

(9) The optical glass as described in (1), wherein TiO is contained in an amount of mass% based on the total mass of the glass in terms of oxide of the composition₂The content of the component (B) is less than 10.0%, and the glass transition point (Tg) is 700 ℃ or lower.

(10) Such as(1) The optical glass contains 10.0 to 30.0% by mass of TiO in terms of oxide of the total mass of the glass₂Component (b) has a glass transition point (Tg) of 700 ℃ or lower.

(11) The optical glass according to any one of (1) to (10), wherein the glass has a composition, in terms of oxides, in terms of mass% of:

WO₃0 to 20.0% of the component(s) and/or

BaO component 0-30.0% and/or

SiO₂0 to 10.0% of the component (A).

(12) The optical glass according to (11), wherein the glass has a composition, in terms of oxides, in mass%:

WO₃the component (A) is more than 0% and less than 20.0%, and

the BaO content is more than 0% and not more than 30.0%.

(13) The optical glass according to (11) or (12), wherein a content of the BaO component is 13.0% by mass or less with respect to a total mass of the glass in terms of oxide of the composition.

(14) The optical glass according to (11) or (12), wherein the content of the BaO component is less than 7.0% by mass with respect to the total mass of the glass in terms of oxide.

(15) The optical glass according to (11) or (12), wherein a content of the BaO component is 4.5% by mass or less with respect to a total mass of the glass in terms of oxide of the composition.

(16) The optical glass according to (11) or (12), wherein the content of the BaO component is 1.0% by mass or more and less than 17.0% by mass with respect to the total mass of the glass in terms of oxide.

(17) The optical glass according to (11) or (12), wherein the content of the BaO component is 2.0% by mass or more and 15.0% by mass or less with respect to the total mass of the glass in terms of oxide of the composition.

(18) The optical glass according to (11) or (12), wherein a content of the BaO component is more than 7.0% and 30.0% or less in mass% with respect to a total mass of the glass in terms of oxide of the composition.

(19) The optical glass as described in any one of (11) to (18), wherein SiO is in mass% with respect to the total mass of the glass in terms of oxide of the composition₂The content of the component is 2.0% or less.

(20) The optical glass as described in any one of (11) to (18), wherein SiO is contained in an amount of more than 2.0% by mass in terms of mass% with respect to the total mass of the glass in terms of oxide of the composition₂And (3) components.

(21) The optical glass as described in any one of (11) to (20), wherein WO is in mass% relative to the total mass of the glass in terms of oxide of the composition₃The content of the component is 10.0% or less.

(22) The optical glass according to any one of (1) to (21), wherein the glass has a composition, in terms of oxides, in terms of mass% of:

Li₂0 to 20.0% of O component and/or

Na₂0 to 35.0% of O component and/or

K₂0 to 20.0% of an O component.

(23) The optical glass according to (22), wherein the glass has a composition, in terms of oxides, in mass%:

Li₂0 to 10.0% of O component and/or

Na₂0 to 15.0% of O component and/or

K₂The content of O is less than 0 to 10.0%.

(24) The optical glass as described in (22) or (23), which contains Li₂An O component as an essential component.

(25) The optical glass as described in any one of (22) to (24), wherein K is in mass% with respect to the total mass of the glass in terms of oxide of the composition₂The content of O component is more than 0.1%.

(26) The optical glass as described in any one of (22) to (25), wherein the total mass, mass and Li of the glass are calculated with respect to oxides₂O+Na₂O+K₂O is 35.0% or less.

(27) The optical glass as described in any one of (22) to (26), wherein the total mass, mass and Li of the glass are calculated with respect to oxides₂O+Na₂O+K₂O is 5.0% to 35.0%.

(28) The optical glass as described in any one of (22) to (27), wherein the total mass, mass and Li of the glass are calculated with respect to oxides₂O+Na₂O+K₂O is greater than 7.0% and 35.0% or less.

(29) The optical glass as described in any one of (22) to (28), wherein the total mass, mass and Li of the glass are calculated with respect to oxides₂O+Na₂O+K₂O is more than 8.0 percent.

(30) The optical glass as described in any one of (22) to (29), wherein the total mass, mass and Li of the glass are calculated with respect to oxides₂O+Na₂O+K₂O is more than 10.0 percent.

(31) The optical glass as described in any one of (22) to (30), wherein the total mass, mass and Li of the glass are calculated with respect to oxides₂O+Na₂O+K₂O is 15.0% or less.

(32) The optical glass as described in any one of (22) to (31), wherein 15.0% by mass or more of a BaO component, a mass and Li are contained in terms of mass% with respect to the total mass of the glass in terms of oxide composition₂O+Na₂O+K₂O is more than 10.0 percent.

(33) The optical glass as described in (22) to (32), which contains Li₂O component and Na₂O component, and K₂More than 2 of the O component.

(34) The optical glass according to any one of (1) to (33), wherein the glass has a composition, in terms of oxides, in terms of mass% of:

MgO component 0-5.0% and/or

CaO content of 0 to 10.0% and/or

0 to 10.0% of SrO.

(35) The optical glass according to (34), wherein the sum of the mass of MgO + CaO + SrO + BaO is 30.0% or less with respect to the total mass of the glass in terms of oxides.

(36) The optical glass according to any one of (1) to (35), wherein the glass has a composition, in terms of oxides, in terms of mass% of:

Y₂O₃0 to 10.0% of the component(s) and/or

La₂O₃0 to 10.0% of the component(s) and/or

Gd₂O₃0 to 10.0% of the component (A).

(37) The optical glass as described in (36), wherein the sum of the mass and Y is the total mass of the glass in terms of oxide converted composition₂O₃+La₂O₃+Gd₂O₃Is 20.0% or less.

(38) The optical glass according to any one of (1) to (37), wherein the glass has a composition, in terms of oxides, in terms of mass% of:

(39) the optical glass as described in any one of (1) to (38), which has a refractive index (nd) of 1.70 or more and 2.20 or less, and has an Abbe number (vd) of 10 or more and 25 or less.

(40) The optical glass according to any one of (1) to (39), which has a chemical durability (acid resistance) of 1 to 5 grade by a powder method.

(41) The optical glass as described in any one of (1) to (40), which has a spectral transmittance at a wavelength (. lamda.) of 70%₇₀) Is 500nm or less.

(42) The optical glass as described in any one of (1) to (41), which has an average linear expansion coefficient (. alpha.) of 150X 10 at-30 to +70 ℃^-7K^-1The following.

(43) An optical element made of the optical glass described in any one of (1) to (42).

(44) A preform for precision press molding, which is made of the optical glass described in any one of (1) to (42).

(45) An optical element obtained by precision press-molding the preform for precision press-molding of (44).

According to the present invention, the refractive index of glass can be increased, the dispersion of glass can be increased, and the transparency of glass to visible light can be improved. Thus providing a refractive index (n)_d) In the desired range and having a low Abbe number (v)_d) And has high transparency to visible light, and an optical element.

In particular, according to the invention, by containing a specific amount of P₂O₅Component (B) and Nb₂O₅Composition providing a refractive index (n) having a desired value_d) Abbe number (v)_d) And an optical glass and an optical element which are transparent to visible light, hardly cause devitrification or clouding when the glass is produced and processed, and are easily manufactured from a preform material and an optical element by polishing.

And, according to the present invention, by containing a specific amount of P₂O₅Component (B) and Nb₂O₅Composition providing a refractive index (n) having a desired value_d) Abbe number (v)_d) And an optical glass and an optical element which are transparent to visible light and can be easily polished and press-molded.

Further, according to the present invention, by using P in combination₂O₅Component (B) and Nb₂O₅And P is₂O₅Component (B) and Nb₂O₅Component (B) and TiO₂The content of the component is controlled within a specific range, and a desired refractive index (n)_d) Abbe number (v)_d) And an optical glass which is transparent to visible light and is easily softened at a low temperature, an optical element using the optical glass, and a preform for precision press molding.

Further, according to the present invention, by using P in combination₂O₅Component (B) and Nb₂O₅Component (C) and contains Li₂O component and Na₂Component O and K₂At least one of the O components is an essential component to provide a refractive index (n) having a desired value_d) Abbe number (v)_d) And an optical glass which is transparent to visible light and is easily softened at a low temperature, an optical element using the optical glass, and a preform for precision press molding.

Further, according to the present invention, by containing a specific amount of P₂O₅Component (B) and Nb₂O₅Composition providing a refractive index (n) having a desired value_d) Abbe number (v)_d) And optical glass and optical elements which are transparent to visible light and at the same time are easy to wash when making preformed materials and optical elements.

Detailed Description

The optical glass of the present invention contains 5.0% to 40.0% by mass of P in terms of oxide of the total mass of the glass₂O₅Component (b), 10.0% to 60.0% Nb₂O₅And (3) components. By using P in combination₂O₅Component (B) and Nb₂O₅And P is₂O₅Component (B) and Nb₂O₅The content of the component is controlled within a specific range, whereby the refractive index of the glass can be increased, the dispersion can be improved, and the transparency of the glass to visible light can be improved. Thus, the refractive index (n) can be provided_d) In the desired range and having a low Abbe number (v)_d) And has high transparency to visible light, and an optical element.

Here, the optical glass according to the first embodiment of the present invention contains, in mass%, 5.0% to 40.0% of P with respect to the total mass of the glass in terms of oxide of the composition₂O₅Component (b), 10.0% to 60.0% Nb₂O₅Component (b) having a wavelength (λ) at which the spectral transmittance is 70%₇₀) Is 500nm or less, and has a liquidus temperature of 500 ℃ to 1200 ℃. By using P in combination₂O₅Component (B) and Nb₂O₅And P is₂O₅Component (B) and Nb₂O₅The content of the component is controlled within a specific range, whereby the refractive index of the glass can be increased, the dispersion can be improved, the transparency of the glass to visible light can be improved, the liquidus temperature of the glass can be lowered, and the acid resistance of the glass can be improved, so that the glass is less likely to be damaged even when the glass is brought into contact with a polishing liquid or a cleaning liquid. Thus, the refractive index (n) can be provided_d) In the desired range while having a low Abbe number (v)_d) An optical glass and an optical element which have high transparency to visible light, are less likely to cause devitrification or clouding when the glass is produced or processed, and are easily produced from a preform or an optical element by polishing.

Furthermore, an optical glass according to a second embodiment of the present invention contains, in mass%, 5.0% to 40.0% of P in relation to the total mass of the glass in terms of oxide of the composition₂O₅Component (b), 10.0% to 60.0% Nb₂O₅The component (A) has an abrasion degree of 100 to 400. By using P in combination₂O₅Component (B) and Nb₂O₅And P is₂O₅Component (B) and Nb₂O₅The content of the component is controlled within a specific range, so that the refractive index of the glass can be increased, the dispersion can be improved to obtain a low Abbe number, the transparency of the glass to visible light can be improved, an appropriate degree of abrasion can be provided, and the average linear expansion coefficient (alpha) is reduced. Thus, the refractive index (n) can be provided_d) An optical glass and an optical element which have a high dispersion (low Abbe number), a high transparency to visible light, and a low pressure forming property, are in a desired range, can be easily polished, and can reduce indentations (depressions) and cracks caused in a lens by pressure forming.

Furthermore, an optical glass according to a third embodiment of the present invention contains, in mass%, 5.0% to 40.0% of P in relation to the total mass of the glass in terms of oxide of the composition₂O₅Component (b), 10.0% to 60.0% Nb₂O₅Component (C) and TiO₂The content of the component (B) is less than 10.0%, and the glass transition point (Tg) is 700 ℃ or lower. By using P in combination₂O₅Component (B) and Nb₂O₅And P is₂O₅Component (B) and Nb₂O₅Component (B) and TiO₂The content of the component(s) is controlled within a specific range, whereby the refractive index of the glass can be increased, the dispersion can be increased to obtain a low Abbe number, the transparency of the glass to visible light can be improved, and the glass transition point (Tg) can be lowered. Thus, the refractive index (n) can be provided_d) In the desired range and having a low Abbe number (v)_d) An optical glass which has high transparency to visible light and is easily press-molded by softening at low temperature, an optical element using the optical glass, and a preform for precision press-molding.

Furthermore, an optical glass according to a fourth embodiment of the present invention contains, in mass%, 5.0% to 40.0% of P in relation to the total mass of the glass in terms of oxide of the composition₂O₅Component (b), 10.0% to 60.0% Nb₂O₅The component (B) has a detergent resistance (PR) of grade 1-3 according to an ISO test method. By using P in combination₂O₅Component (B) and Nb₂O₅And P is₂O₅Component (B) and Nb₂O₅The content of the component is controlled within a specific range, so that the refractive index of the glass can be increased, the dispersion can be improved, the transparency of the glass to visible light can be improved, and the detergent resistance of the glass can be improved, so that the glass is not easily damaged even if the glass is contacted with a polishing liquid or a cleaning liquid. Thus, the refractive index (n) can be provided_d) In the desired range and having a low Abbe number (v)_d) An optical glass and an optical element which have high transparency to visible light, are less likely to be turbid when the glass after polishing is washed, and are easily washed when a preform material or an optical element is produced.

Furthermore, an optical glass according to a fifth embodiment of the present invention contains, in mass%, 5.0% to 40.0% of P in relation to the total mass of the glass in terms of oxide of the composition₂O₅Component (b), 10.0% to 60.0% Nb₂O₅Component (b), and 10.0% to 30.0% TiO₂Component (b) has a glass transition point (Tg) of 700 ℃ or lower. By using P in combination₂O₅Component (B) and Nb₂O₅Component (B) and TiO₂And P is₂O₅Component (B) and Nb₂O₅Component (B) and TiO₂The content of the component(s) is controlled within a specific range, whereby the refractive index of the glass can be increased, the dispersion can be increased to obtain a low Abbe number, the transparency of the glass to visible light can be improved, and the glass transition point (Tg) can be lowered. Thus, the refractive index (n) can be provided_d) In the desired range and having a low Abbe number (v)_d) An optical glass which has high transparency to visible light and is easily press-molded by softening at low temperature, an optical element using the optical glass, and a preform for precision press-molding.

Furthermore, an optical glass according to a sixth embodiment of the present invention contains, in mass%, 5.0% to 40.0% of P in relation to the total mass of the glass in terms of oxide of the composition₂O₅Component (b), 10.0% to 60.0% Nb₂O₅Component (C) and contains Li₂O component and Na₂Component O and K₂At least one of the O components has a glass transition point (Tg) of 700 ℃ or lower as an essential component. By using P in combination₂O₅Component (B) and Nb₂O₅Component (C) and contains Li₂O component and Na₂Component O and K₂At least one of the O components is an essential component, and the glass can have a high refractive index, can have a high dispersion to have a low Abbe number, can have a high transparency to visible light, and has a low glass transition point (Tg). Thus, the refractive index (n) can be provided_d) In the desired range and having a low Abbe number (v)_d) An optical glass which has high transparency to visible light and is easily press-molded by softening at low temperature, an optical element using the optical glass, and a preform for precision press-molding.

The optical glass of the present invention is produced by the following method, and the optical glass of the present invention is not limited to the above-described embodiments. Note that, although the description of the overlapping portions may be omitted as appropriate, the gist of the present invention is not limited thereto.

[ glass composition ]

The compositional ranges of the respective components constituting the optical glass of the present invention are as follows. Unless otherwise specified, the content of each component is expressed by mass% based on the total mass of the glass in terms of oxides. The "composition in terms of oxide" refers to the composition of each component contained in the glass, assuming that all of the oxides, complex salts, metal fluorides, and the like used as the raw materials of the glass composition components of the present invention are decomposed and converted into oxides during melting, with the total mass of the generated oxides taken as 100 mass%.

< As essential Components, optional Components >

P₂O₅The component (b) is a glass-forming component and is a component that lowers the melting temperature of the glass. In particular, by reacting P₂O₅The content of the component (A) is 5.0% or more, so that the transmittance of the glass in the visible light region can be improved, and the abrasion degree of the glass is not easily increased to a specific range or more, whereby the damage caused by polishing can be reduced. On the other hand, by making P₂O₅The content of the component (b) is 40.0% or less, a desired high refractive index can be obtained, and the abrasion degree of the glass is not easily reduced to a specific range or more, so that the processing efficiency of the polishing process can be improved. Thus, P is the total mass of the glass in terms of the oxide equivalent composition₂O₅The lower limit of the content of the component (a) is preferably 5.0%, more preferably 8.0%, most preferably 10.0%, and the upper limit is preferably 40.0%, more preferably 35.0%, even more preferably 33.0%, most preferably 30.0%. For example, Al (PO) can be used₃)₃、Ca(PO₃)₂、Ba(PO₃)₂、BPO₄、H₃PO₄Etc. as raw materials, containing P in the glass₂O₅And (3) components.

Nb₂O₅The component is a component that increases the refractive index and dispersion of the glass. In particular, by reacting Nb₂O₅The content of the component (A) is 10.0% or more, and a desired high refractive index and high dispersion can be obtained. On the other hand, by using Nb₂O₅The content of the component (b) is 60.0% or less, and the stability of the glass can be improved by suppressing the increase in the liquidus temperature of the glass, and therefore the devitrification resistance of the glass can be improved. Therefore, Nb is added to the total mass of the glass in terms of oxide₂O₅The lower limit of the content of the component (a) is preferably 10.0%, more preferably 20.0%, most preferably 30.0%, and the upper limit thereof is preferably 60.0%, more preferably 58.0%, even more preferably 57.0%, even more preferably 56.0%, most preferably 55.0%. In particular, in the optical glass of the sixth embodiment, the Nb is₂O₅The upper limit of the content of the component is preferably 60.0%, more preferably 50.0%, and most preferably 45.0%. It is possible to use, for example, Nb₂O₅Etc. as raw materials, containing Nb in the glass₂O₅And (3) components.

TiO₂The component is a component for improving the refractive index and dispersion of the glass, a component for improving the chemical durability of the glass, particularly the resistance to detergent and acid, and is an optional component in the optical glass of the present invention. In particular, by making TiO₂The content of the component (A) is 30.0% or less, and the glass can have a high refractive index and a high dispersion, and can be stabilized by suppressing an increase in the liquidus temperature of the glass, whereby the glass can have improved devitrification resistance. Thus, TiO is added to the total mass of the glass in terms of oxide equivalent composition₂The upper limit of the content of the component is preferably 30.0%, more preferably 28.0%, still more preferably 25.0%, and most preferably 20.0%. Wherein, in the optical glasses of the first and second embodiments, by making TiO₂The content of the component (A) is 12.0% or less, and the glass can have a high refractive index and dispersion, and particularly, can have improved transparency to visible light. At this time, the above TiO compound₂The upper limit of the content of the component is preferably 12.0%, more preferably 11.0%, and most preferably less than 10.0%. In the optical glass of the third embodiment, TiO is used₂The content of the component is less than 10.0%, and the glass has high refractive index and high dispersion, and can improve visibilityTransparency of light. At this time, the above TiO compound₂The upper limit of the content of the component is preferably less than 10.0%, more preferably 9.8%, and most preferably 9.5%. In the optical glass of the present invention, TiO may be used particularly for obtaining a glass having high transparency to visible light₂The content of the component is less than 5.0%. On the other hand, in the optical glass of the fifth embodiment, TiO is used₂The content of the component (A) is 10.0% or more, and the dispersion of the glass can be further improved. Therefore, in the case of further realizing high dispersion of the glass, the above TiO compound₂The lower limit of the component content is preferably 10.0%, more preferably 12.0%, still more preferably 13.0%, and most preferably 14.0%.

In addition, even if TiO is not contained₂The optical glass having desired properties can be obtained by using the component (A), but by containing 0.1% or more of TiO₂The component (A) can improve the acid resistance of the glass, and thus can reduce the discoloration of the glass during processing. Therefore, TiO is present at this time relative to the total mass of the glass in terms of oxide converted composition₂The lower limit of the content of the component (b) is preferably 0.1%, more preferably 1.0%, and most preferably 2.0%. In this case, the above TiO can be used to achieve higher acid resistance₂The lower limit of the content of the component (b) is preferably 5.0%, more preferably 11.0%, and most preferably 12.0%. It is possible to use, for example, TiO₂Etc. as raw materials, the glass contains TiO₂And (3) components.

The BaO component is a component for increasing the refractive index of the glass, and is a component for increasing resistance to devitrification by lowering the liquidus temperature of the glass, and is an optional component in the optical glass of the present invention. Among them, when the content of the BaO component is 30.0% or less, a desired high refractive index can be easily obtained, and a decrease in resistance to devitrification and a decrease in chemical durability such as acid resistance can be suppressed. In particular, by setting the content of the BaO component to 20.0% or less, the increase in the average linear expansion coefficient (α) of the glass can be suppressed. Therefore, the upper limit of the content of the BaO component is preferably 30.0%, more preferably 28.0%, further preferably 25.0%, and most preferably 20.0% with respect to the total mass of the glass in terms of oxides. Among them, in the optical glasses of the first and second embodiments, the upper limit of the content of the BaO component is preferably 20.0%, more preferably 18.0%, and most preferably 15.0%. In the optical glass of the third embodiment, the upper limit of the content of the BaO component is preferably 20.0%, more preferably 19.0%, and most preferably 18.0%.

Among these, in particular, from the viewpoint of obtaining a glass having a large dispersion (small abbe number), the upper limit of the content of the BaO component is preferably less than 17.0%, more preferably 13.0%, and most preferably 4.5% with respect to the total mass of the glass in terms of oxide. Among them, in the optical glasses of the first and second embodiments, the upper limit of the content of the BaO component is preferably 13.0%, more preferably less than 10.0%, and most preferably 4.5%. In the optical glass of the third embodiment, the content of the BaO component is preferably less than 17.0%, more preferably less than 15.0%, and most preferably less than 13.0%. In the optical glass of the fifth embodiment, the upper limit of the content of the BaO component is preferably 15.0%, more preferably 13.0%, and most preferably less than 10.0%. In the optical glass of the sixth embodiment, the content of the BaO component is preferably less than 7.0%, more preferably less than 5.0%, and most preferably less than 4.0%.

Further, although it is possible to obtain an optical glass having desired high dispersion and high transmittance without containing BaO component, since the liquidus temperature of the glass can be lowered by containing more than 0% BaO component, it is possible to obtain a glass having high devitrification resistance and being easily and stably produced. Therefore, when obtaining a glass having high devitrification resistance, the lower limit of the content of the BaO component is preferably more than 0%, more preferably 1.0%, and most preferably 3.0% with respect to the total mass of the glass in terms of oxides. In the optical glass of the third embodiment, the lower limit of the content of the BaO component is preferably 1.0%, more preferably 3.0%, and most preferably 4.5%. In the optical glass of the fifth embodiment, the lower limit of the content of the BaO component is preferably greater than 0%, more preferably 1.0%, and most preferably 2.0%. In the optical glass of the sixth embodiment, the lower limit of the content of the BaO component is preferably 0.1%, and more preferably 0.1%Preferably 0.5%, most preferably 1.0%. On the other hand, by containing more than 7.0% of BaO component, the liquidus temperature of the glass can be lowered and the detergent resistance of the glass can be improved. Therefore, when a glass having high resistance to washing agents is obtained, the lower limit of the content of the BaO component is preferably 7.0%, more preferably 10.0%, and most preferably 15.0%. For example, BaCO can be used₃、Ba(NO₃)₂、BaF₂And the glass contains BaO component as raw material.

SiO₂The component (A) is a component which reduces coloring, improves transmittance to short-wavelength visible light, promotes formation of a stable glass, and improves resistance to devitrification of the glass, and is an optional component in the optical glass of the present invention. In particular by making SiO₂The content of the component is 10.0% or less, and SiO can be inhibited₂The lowering of the refractive index by the component, and thus a desired high refractive index can be easily obtained. Thus, SiO represents the total mass of the glass in terms of the oxide equivalent composition₂The upper limit of the content of the component (b) is preferably 10.0%, more preferably 8.0%, still more preferably 6.0%, and most preferably 5.0%. Among them, the SiO is particularly preferred in that a glass having a large dispersion (small Abbe number) can be easily obtained₂The upper limit of the content of the component (b) is preferably 2.0%, more preferably 1.5%, and most preferably 1.0%.

Therefore, even if SiO is reduced₂The content of the component(s) being either SiO-free₂It is also possible to obtain an optical glass having desired high dispersion and high transmittance. On the other hand, in particular, in the optical glass of the 2 nd, by containing more than 2.0% of SiO₂The component (B) can improve the abrasion degree of the glass, and thus can obtain the glass which is easy to be shaped by grinding. Thus, SiO is present in this case relative to the total mass of the glass in terms of the composition of oxides₂The lower limit of the content of the component (b) is preferably more than 2.0%, more preferably 3.0%, and most preferably 4.0%. It is possible to use, for example, SiO₂、K₂SiF₆、Na₂SiF₆Etc. as raw materials, the glass contains SiO₂And (3) components.

WO₃The ingredient is increasedThe component for increasing the refractive index of the glass and the dispersion of the glass is an optional component in the optical glass of the present invention. In particular, by reacting WO₃The content of the component (B) is 20.0% or less, whereby the glass can be improved in devitrification resistance, the glass transition point (Tg) can be reduced, and the glass can be suppressed in transmittance to short-wavelength visible light. Thus, WO is based on the total mass of the glass in terms of the oxide equivalent composition₃The upper limit of the content of the component (b) is preferably 20.0%, more preferably 17.0%, still more preferably 15.0%, and most preferably 10.0%. Among them, WO is particularly effective in that a glass having a desired high dispersion and a low glass transition point (Tg) can be easily obtained₃The content of the component (B) is preferably 10.0% or less. Thus, in this case, the above-mentioned WO₃The upper limit of the content of the component (b) is preferably 10.0%, more preferably 8.0%, still more preferably 7.0%, and most preferably 5.0%.

In addition, even if WO is not contained₃The composition also enables to obtain an optical glass having a desired high dispersion and high transmittance, but by containing more than 0% of WO₃The component (A) can increase the dispersion of the glass, and thus the glass can easily have both high dispersion and transparency to visible light. Thus, in this case WO, relative to the total mass of the glass in terms of the oxide of the composition₃The lower limit of the content of the component (b) is preferably more than 0%, more preferably 1.0%, still more preferably 3.0%, and most preferably 4.0%. It is possible to use, for example, WO₃Etc. as raw materials, and the glass contains WO₃And (3) components.

Li₂The O component is a component for lowering the melting temperature and glass transition point (Tg) of the glass, and is a component for improving resistance to devitrification at the time of glass formation, and is an optional component in the optical glass of the present invention. Wherein by reacting Li₂The content of the O component is 20.0% or less, a desired high refractive index can be easily obtained, and the liquid phase temperature of the glass can be lowered to improve the stability of the glass, whereby devitrification of the glass can be reduced. In particular, by reacting Li₂The content of the O component is 10.0% or less, and the increase of the average linear expansion coefficient (alpha) of the glass can be suppressed. Therefore, Li represents the total mass of the glass in terms of the composition of oxides₂Content ratio of O componentThe upper limit is preferably 20.0%, more preferably 10.0%, and most preferably 5.0%. In particular, in the optical glasses of the first and second embodiments, the above-mentioned Li₂The upper limit of the content of the O component is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. In the optical glasses of the third and fourth embodiments, the above-mentioned Li₂The upper limit of the content of the O component is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. Further, in the optical glasses of the fifth and sixth embodiments, the above-mentioned Li₂The upper limit of the content of the O component is preferably 20.0%, more preferably 18.0%, further preferably 15.0%, and most preferably 10.0%.

In addition, even if Li is not contained₂The O component may also give an optical glass having desired high dispersion and high transmittance, but by containing more than 0% of Li₂The O component can lower the glass transition point (Tg), and thus a glass having high dispersion and being easily softened at low temperature can be obtained. Therefore, Li in this case is based on the total mass of the glass in terms of the composition of oxides₂The lower limit of the content of the component O is preferably more than 0%, more preferably more than 0.3%, and most preferably 0.5%. It is possible to use, for example, Li₂CO₃、LiNO₃LiF, etc. as raw materials, and Li is contained in the glass₂And (4) an O component.

Na₂The O component is a component for lowering the melting temperature and glass transition point (Tg) of the glass, and is a component for improving resistance to devitrification at the time of glass formation, and is an optional component in the optical glass of the present invention. In particular, by reacting Na₂The content of the O component is 35.0% or less, a desired high refractive index can be easily obtained, the liquidus temperature of the glass can be lowered to improve the stability of the glass, and devitrification of the glass can be reduced. Therefore, Na represents the total mass of the glass in terms of the oxide equivalent composition₂The upper limit of the content of the O component is preferably 35.0%, more preferably 25.0%, and most preferably 15.0%. In particular, in the optical glass of the first embodiment, Na is as described above₂The upper limit of the content of the O component is preferably 15.0%, more preferably 12.0%, and most preferably 10.0%. In the optical glass of claim 2, the above Na₂Upper limit of O component contentPreferably 15.0%, more preferably 13.0%, most preferably 12.0%. In the optical glasses of the third and fourth embodiments, Na is as described above₂The upper limit of the content of the O component is preferably 35.0%, more preferably 30.0%, still more preferably 25.0%, and most preferably 15.0%. In the optical glasses of the fifth and sixth embodiments, Na is as described above₂The upper limit of the content of the O component is preferably 35.0%, more preferably 30.0%, still more preferably 25.0%, and most preferably 20.0%.

In addition, even if Na is not contained₂The O component can also provide optical glass having desired properties, but 0.1% or more of Na is contained₂The O component can raise the liquidus temperature of the glass, and thus can further improve the devitrification resistance of the glass. Therefore, Na represents the total mass of the glass in terms of the oxide content₂The lower limit of the content of the O component is preferably 0.1%, more preferably 0.5%, still more preferably 1.0%, and most preferably 2.0%. For example, Na can be used₂CO₃、NaNO₃、NaF、Na₂SiF₆Etc. as raw materials, the glass contains Na₂And (4) an O component.

K₂The O component is a component for lowering the melting temperature and glass transition point (Tg) of the glass and a component for improving resistance to devitrification at the time of glass formation, and is an optional component in the optical glass of the present invention. In particular, by making K₂The content of the O component is 20.0% or less, a desired high refractive index can be easily obtained, and the liquid phase temperature of the glass can be lowered to improve the stability of the glass, thereby reducing the occurrence of devitrification of the glass. Thus, K is the total mass of the glass in terms of the oxide equivalent composition₂The upper limit of the content of the O component is preferably 20.0%, more preferably 15.0%, and most preferably less than 10.0%. In particular, in the optical glasses of the first and second embodiments, K is as defined above₂The upper limit of the content of the O component is preferably less than 10.0%, more preferably 8.0%, further preferably 6.0%, and most preferably 5.0%. In the optical glasses of the third and fourth embodiments, K is as defined above₂The upper limit of the content of the O component is preferably 20.0%, more preferably 15.0%, and still more preferably 120%, most preferably 10.0%. Further, in the optical glasses of the fifth and sixth embodiments, K is the above₂The upper limit of the content of the O component is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%.

In addition, even if K is not contained₂The optical glass having desired characteristics can be obtained by containing 0.1% or more of K as the O component₂The O component can raise the liquidus temperature of the glass, and thus can improve the devitrification resistance of the glass. Therefore, K is calculated based on the total mass of the glass in terms of the oxide of the composition₂The lower limit of the content of the O component is preferably 0.1%, more preferably 0.15%, further preferably 0.2%, further preferably 0.5%, most preferably 1.0%. Can use K₂CO₃、KNO₃、KF、KHF₂、K₂SiF₆Etc. as raw materials, the glass contains K₂And (4) an O component.

Among them, the optical glass of the sixth embodiment preferably contains Li₂O component and Na₂O component, and K₂At least one of the O components is an essential component. Thus, the glass transition point (Tg) of the optical glass is lowered, so that the molding temperature at the time of press molding can be lowered, and the occurrence of unevenness or cloudiness on the surface after press molding can be further reduced. Further, since resistance to devitrification of the optical glass can be improved, an optical glass having desired optical characteristics can be produced more stably.

In the optical glass of the present invention, Rn₂The sum of the contents of O components (Rn is1 or more selected from Li, Na and K in the formula) is preferably 35.0% or less. This can suppress a decrease in the refractive index of the glass, and thus can easily obtain a desired high refractive index. Further, by lowering the liquidus temperature of the glass, the stability of the glass can be improved, and thus the devitrification resistance of the glass can be improved. Rn is thus based on the total mass of the glass in terms of oxide-reduced composition₂The upper limit of the mass sum of the content of the O component is preferably 35.0%, more preferably 25.0%, and most preferably 15.0%. In particular, in the optical glasses of the first and second embodiments, the upper limit value of the sum of the above-mentioned masses is preferably 15.0%, more preferably 13.0% >, and,Most preferably 12.0%. In the optical glass of the third embodiment, the upper limit value of the sum of the masses is preferably 35.0%, more preferably 32.0%, and most preferably 30.0%. In the optical glass of the fourth embodiment, the upper limit of the sum of the masses is preferably 35.0%, more preferably 25.0%, and most preferably 20.0%. In the optical glasses according to the fifth and sixth embodiments, the upper limit of the sum of the masses is preferably 35.0%, more preferably 30.0%, and most preferably 25.0%.

In addition, even if no Rn is contained₂The O component can also provide an optical glass having desired characteristics, but the O component is added in an amount of 0.1% or more of Rn₂At least one of the O components can raise the liquidus temperature of the glass, and thus can further improve the devitrification resistance of the glass. Therefore, Rn is present at this time relative to the total mass of the glass of the oxide-converted composition₂The lower limit of the mass sum of the O component contents is preferably 0.1%, more preferably 1.0%, even more preferably 2.0%, and most preferably 3.0%.

Furthermore, by making Rn₂The sum of the contents of O and O is 5.0% or more, whereby high dispersion of the glass can be achieved, the glass transition point (Tg) can be reduced, and the water resistance and detergent resistance of the glass can be improved. Rn is thus based on the total mass of the glass in terms of oxide-reduced composition₂The lower limit of the mass sum of the content of the O component is preferably 5.0%, more preferably 8.0%, and most preferably 10.0%. Among them, in the optical glass of the third embodiment, the lower limit value of the sum of mass is preferably more than 7.0%, more preferably 9.0%, and most preferably 10.0%. In the optical glass of the fourth embodiment, the sum of the masses is preferably greater than 8.0%, more preferably greater than 9.0%, and most preferably greater than 10.0%. In the optical glass of the fifth embodiment, the lower limit of the sum of the masses is preferably 5.0%, more preferably 6.0%, and most preferably 7.0%. In the optical glass according to the sixth embodiment, the lower limit of the sum of the masses is preferably 5.0%, more preferably 8.0%, and most preferably 10.0%.

In particular, in the optical glass according to the fourth embodiment of the present invention, the total glass mass in terms of oxide equivalent composition is particularly preferableThe amount of BaO component is 15.0% or more by mass%, and Rn is more than 10.0% by total mass₂And (4) an O component. This can improve the detergent resistance of the glass, and can reduce the occurrence of turbidity of the glass even when the glass is brought into contact with a polishing liquid or a cleaning liquid.

The optical glass of the present invention preferably contains Li₂O component and Na₂O component and K₂More than 2 of the O component. This can reduce the glass transition point (Tg) of the optical glass, lower the molding temperature during press molding, and further reduce the occurrence of irregularities and cloudiness on the surface after press molding. Further, since resistance to devitrification of the optical glass can be improved, an optical glass having desired optical characteristics can be produced more stably.

The MgO component is a component for lowering the liquidus temperature of the glass and improving the devitrification resistance of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the MgO component content to 5.0% or less, a desired high refractive index and high dispersion can be easily obtained. Therefore, the upper limit of the content of the MgO component is preferably 5.0%, more preferably 4.0%, and most preferably 3.0% with respect to the total mass of the glass in terms of oxides. For example MgCO may be used₃、MgF₂And the like, and the glass contains MgO component.

The CaO component is a component for lowering the liquidus temperature of the glass and improving the devitrification resistance of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the CaO component to 10.0% or less, a desired high refractive index and high dispersion can be easily obtained, and deterioration in devitrification resistance and chemical durability can be suppressed. Therefore, the upper limit of the content of CaO component is preferably 10.0%, more preferably 8.0%, further preferably 6.0%, and most preferably 5.0% with respect to the total mass of the glass in terms of oxides. It is possible to use, for example, CaCO₃、CaF₂Etc. as the raw material, the glass contains CaO component.

The SrO component is a component for lowering the liquidus temperature of the glass and improving the devitrification resistance of the glass, and is an optional component in the optical glass of the present invention. In particular, by making SrO componentThe content ratio is 10.0% or less, a desired high refractive index and high dispersion can be easily obtained, and deterioration in resistance to devitrification and chemical durability can be suppressed. Therefore, the upper limit of the content of the SrO component is preferably 10.0%, more preferably 8.0%, and most preferably 5.0% with respect to the total mass of the glass in terms of oxides. Use may be made of, for example, Sr (NO)₃)₂、SrF₂And the like, wherein the glass contains an SrO component.

In the optical glass of the present invention, the sum of the contents of RO components (in the formula, R represents one or more of Mg, Ca, Sr, and Ba) is preferably 30.0% or less by mass. This can suppress the decrease in refractive index and dispersion due to the RO component, and thus can easily obtain a desired high refractive index and high dispersion. Therefore, the upper limit of the sum of the RO component contents by mass is preferably 30.0%, more preferably 20.0%, and most preferably 10.0% with respect to the total mass of the glass in terms of oxide. In particular, in the optical glasses of the first and second embodiments, the upper limit value of the sum of the masses is preferably 20.0%, more preferably 17.0%, more preferably 15.0%, and most preferably 10.0%. In the optical glasses according to the third and fourth embodiments, the upper limit of the sum of the masses is preferably 30.0%, more preferably 28.0%, still more preferably 27.0%, and most preferably 25.0%. In the optical glasses according to the fifth and sixth embodiments, the upper limit of the sum of the masses is preferably 30.0%, more preferably 25.0%, and most preferably 20.0%.

Further, an optical glass having desired characteristics can be obtained even if no RO component is contained, but the addition of at least one of RO components in an amount of 0.1% or more can increase the liquidus temperature of the glass, and thus the devitrification resistance of the glass can be further improved. Therefore, the lower limit of the sum of the RO component contents by mass in this case is preferably 0.1%, more preferably 0.5%, even more preferably 1.0%, and most preferably 3.0% with respect to the total mass of the glass in terms of oxide.

Y₂O₃The component (A) is a component for increasing the refractive index of the glass and simultaneously improving the chemical durability of the glass, and is an optional component in the optical glass of the present invention. In particular, by reacting Y₂O₃Of ingredientsThe content is 10.0% or less, and the desired high dispersion can be easily obtained, and the resistance to devitrification of the glass can be improved. Thus, Y is based on the total mass of the glass in terms of the oxide equivalent composition₂O₃The upper limit of the content of the component (b) is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. Use may be made of, for example, Y₂O₃、YF₃Etc. as raw materials, containing Y in the glass₂O₃And (3) components.

La₂O₃The component (A) is a component for increasing the refractive index of the glass and simultaneously improving the chemical durability of the glass, and is an optional component in the optical glass of the present invention. In particular, by subjecting La₂O₃The content of the component (B) is 10.0% or less, and the desired high dispersion can be easily obtained, and the devitrification resistance of the glass can be improved. Therefore, La is added to the total mass of the glass in terms of oxide equivalent composition₂O₃The upper limit of the content of the component (b) is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. For example, La can be used₂O₃、La(NO₃)₃·XH₂O (X is an arbitrary integer) or the like as a raw material, and La is contained in the glass₂O₃And (3) components.

Gd₂O₃The component (A) is a component for increasing the refractive index of the glass and simultaneously improving the chemical durability of the glass, and is an optional component in the optical glass of the present invention. In particular, by reacting Gd₂O₃The content of the component (B) is 10.0% or less, and the desired high dispersion can be easily obtained, and the devitrification resistance of the glass can be improved. Thus, Gd represents the total mass of the glass in terms of oxide content₂O₃The upper limit of the content of the component (b) is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. For example Gd may be used₂O₃、GdF₃Etc. as raw materials, the glass contains Gd₂O₃And (3) components.

In the optical glass of the present invention, Ln₂O₃The sum of the contents of the components (Ln is1 or more selected from Y, La and Gd in the formula) is preferably 20.0% or less. By setting the sum of these masses to 20.0% or less, Ln can be suppressed₂O₃The Abbe number is increased by the component, and thus a desired high dispersion is easily obtained. Thus, Ln is calculated with respect to the total mass of the glass in terms of oxide₂O₃The upper limit of the mass sum of the component contents is preferably 20.0%, more preferably 18.0%, and most preferably 15.0%.

B₂O₃The component (B) is a component for promoting the formation of a stable glass and improving the resistance to devitrification, and is an optional component in the optical glass of the present invention. In particular, by reacting B₂O₃The content of component (B) is 10.0% or less, and B can be inhibited₂O₃The lowering of the refractive index by the component makes it easy to obtain a desired high refractive index. Further, this can suppress an increase in the average linear expansion coefficient (α) of the glass. Thus, B is the total mass of the glass in terms of the oxide equivalent composition₂O₃The upper limit of the content of the component (b) is preferably 10.0%, more preferably 8.0%, still more preferably 6.0%, and most preferably 5.0%. Furthermore, even if B is not contained₂O₃An optical glass having desired characteristics can be obtained by the component (B), but the content of B is 0.1% or more₂O₃The component (B) can raise the liquidus temperature of the glass, and thus can further improve the devitrification resistance of the glass. Thus, B represents the total mass of the glass in terms of oxide equivalent composition₂O₃The lower limit of the content of the component (b) is preferably 0.1%, more preferably 0.2%, still more preferably 0.3%, and most preferably 0.5%. May be used, for example, as H₃BO₃、Na₂B₄O₇、Na₂B₄O₇·10H₂O、BPO₄Etc. as raw materials, the glass contains B₂O₃And (3) components.

GeO₂The component (A) is a component for increasing the refractive index of the glass, promoting the formation of a stable glass, and improving the devitrification resistance of the glass, and is an optional component in the optical glass of the present invention. In particular, by reacting GeO₂The content of the component is 10.0% or less, and the material cost of the glass can be reduced. Thus, GeO is the amount of GeO relative to the total mass of the glass in terms of the oxide converted composition₂The upper limit of the component content is preferably 10.0%, more preferably 8%.0%, most preferably 5.0%. It is possible to use, for example, GeO₂Etc. as raw materials, containing GeO in the glass₂And (3) components.

Bi₂O₃The component (A) is a component for increasing the refractive index of the glass and increasing the dispersion of the glass, and is an optional component in the optical glass of the present invention. In particular, by reacting Bi₂O₃The content of the component (A) is 20.0% or less, and the stability of the glass can be improved to suppress the decrease in resistance to devitrification and the decrease in transmittance of the glass can be suppressed. Therefore, Bi is contained in the glass in terms of the total mass of the glass in terms of oxide₂O₃The upper limit of the component content is preferably 20.0%, more preferably 15.0%, still more preferably less than 10.0%, and most preferably less than 5.0%.

ZrO₂The component (A) is a component which reduces coloring to improve transmittance to short-wavelength visible light and promotes formation of a stable glass to improve devitrification resistance of the glass, and is an optional component in the optical glass of the present invention. In particular, by reacting ZrO₂The content of the component (A) is 10.0% or less, and ZrO can be inhibited₂The lowering of the refractive index by the component makes it possible to easily obtain a desired high refractive index. Thus, ZrO based on the total mass of the glass of the oxide-converted composition₂The upper limit of the content of the component (b) is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. It is possible to use, for example, ZrO₂、ZrF₄Etc. as raw materials, with ZrO contained in the glass₂And (3) components.

The ZnO component is a component for lowering the liquidus temperature of the glass and for improving the devitrification resistance of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the ZnO component to 10.0% or less, a desired high refractive index and high dispersion can be easily obtained. Therefore, the upper limit of the content of the ZnO component is preferably 10.0%, more preferably 8.0%, and most preferably 5.0% with respect to the total mass of the glass in terms of oxides. For example, ZnO, ZnF can be used₂Etc. as the raw material, the glass contains a ZnO component.

Al₂O₃The component (A) is a component which improves the chemical durability of the glass and also improves the viscosity of the glass when moltenIn particular, the optical glass of the present invention is an optional component. In particular, by reacting Al₂O₃The content of the component (A) is 10.0% or less, and the meltability of the glass can be improved and the devitrification tendency of the glass can be reduced. Further, an increase in the average linear expansion coefficient (α) can be suppressed. Therefore, Al is contained in the glass in terms of the total mass of the glass in terms of oxides₂O₃The upper limit of the content of the component (b) is preferably 10.0%, more preferably 8.0%, and most preferably 5.0%. For example, Al can be used₂O₃、Al(OH)₃、AlF₃Etc. as raw materials, the glass contains Al₂O₃And (3) components.

Ta₂O₅The component (C) is a component for increasing the refractive index of the glass and is an optional component in the optical glass of the present invention. In particular, by reacting Ta₂O₅The content of the component (B) is 10.0% or less, and thus the glass is less likely to devitrify. Therefore, Ta is the total mass of the glass in terms of the composition of oxides₂O₅The upper limit of the content of the component (b) is preferably 10.0%, more preferably 8.0%, and most preferably 4.0%. It is possible to use, for example, Ta₂O₅Etc. as raw materials, and Ta is contained in the glass₂O₅And (3) components.

Sb₂O₃The component (A) is a component which improves the transmittance of the glass to short-wavelength visible light and has a defoaming effect when the glass is melted. In particular, by reacting Sb₂O₃The content of the component is less than 1.0%, Sb₂O₃The components are difficult to alloy with melting equipment (particularly noble metals such as Pt) and reduce impurities attached to a mold, so that the generation of unevenness or turbidity on the surface of a glass formed body can be reduced. Thus, Sb is relative to the total mass of the oxide basis₂O₃The upper limit of the content of the component (C) is preferably 1.0%, more preferably 0.8%, most preferably 0.5%. Sb may be used, for example₂O₃、Sb₂O₅、Na₂H₂Sb₂O₇·5H₂O or the like as a raw material, and Sb is contained in the glass₂O₃And (3) components.

It should be noted that the glass is refinedThe component for defoaming is not limited to Sb₂O₃As the component (b), a refining agent, a defoaming agent or a combination thereof known in the glass production field can be used.

< about an ingredient which should not be contained >

Next, components that should not be contained in the optical glass of the present invention and components that are not preferably contained therein will be described.

Other components may be added to the optical glass of the present invention as needed within a range not to impair the characteristics of the glass of the present invention.

Further, it is preferable that the optical glass using a wavelength in the visible region substantially does not contain any of the above-mentioned metal components, particularly in the optical glass using a wavelength in the visible region, because each of the transition metal components of V, Cr, Mn, Fe, Co, Ni, Cu, Ag, Mo, and the like other than Ti, Zr, Nb, W, La, Gd, Y, Yb, Lu colors the glass and has a property of absorbing a specific wavelength in the visible region even when the transition metal component is contained in a small amount singly or in a small amount in combination.

In addition, since the use of lead compounds such as PbO and the respective components Th, Cd, Tl, Os, Be, and Se as harmful chemical substances tends to Be controlled in recent years, measures are required in terms of environmental measures not only in the glass production process but also in the processing process and the treatment after the product formation. Therefore, when importance is attached to the influence of the environment, it is preferable that these components are not substantially contained unless inevitably mixed. Thus, the optical glass can be substantially free of substances contaminating the environment. Therefore, even if special measures are not taken in terms of environmental countermeasures, the optical glass can be manufactured, processed, and discarded.

The composition of the glass composition of the present invention is expressed by mass% of the total mass of the glass with respect to the composition in terms of oxides, and is not directly expressed by mol%, but the composition of each component present in the glass composition satisfying various characteristics required by the present invention is approximately the following value in terms of the composition in terms of oxides.

In the optical glasses of the first and second embodiments, the composition of each component expressed in mol% is substantially as follows in terms of oxide.

In the optical glass of the third embodiment, the composition of each component expressed in mol% is substantially the following value in terms of oxide-converted composition.

In the optical glass of the fourth embodiment, the composition of each component expressed in mol% is substantially the following value in terms of oxide-converted composition.

In the optical glass of the fifth embodiment, the composition of each component expressed in mol% is substantially the following value in terms of oxide-converted composition.

In the optical glass of the sixth embodiment, the composition of each component expressed in mol% is substantially the following value in terms of oxide-converted composition.

[ production method ]

The optical glass of the present invention can be produced, for example, in the following manner. That is, the raw materials are uniformly mixed so that the contents of the respective components fall within a specific range, the resulting mixture is put into a quartz crucible or an aluminum crucible to be roughly melted, then put into a platinum crucible, a platinum alloy crucible or an iridium crucible to be melted at a temperature of 1000 to 1300 ℃ for 2 to 10 hours, stirred and homogenized, and subjected to defoaming, and then cooled to 1250 ℃ or less, followed by fine stirring (Shishanzu stirring) to remove veins, and the mixture is cast into a mold to be slowly cooled.

[ Properties ]

The optical glass of the present invention is required to have both a high refractive index (n)_d) And also has high dispersion. In particular, the refractive index (n) of the optical glass of the present invention_d) The lower limit of (b) is preferably 1.70, more preferably 1.75, further preferably 1.80, most preferably 1.90, and the upper limit is preferably 2.20, more preferably 2.15, most preferably 2.10. Further, the Abbe number (v) of the optical glass of the present invention_d) The upper limit of (b) is preferably 25, more preferably 22, still more preferably 20, and most preferably 19. This can increase the degree of freedom in optical design and obtain a large amount of light refraction even if the element is made thin. The Abbe number (v) of the optical glass of the present invention_d) The lower limit of (b) is not particularly limited, and in many cases, the Abbe number (v) of the glass obtained by the present invention_d) Approximately 10 or more, specifically 12 or more, more specifically 15 or more.

Further, the optical glass of the present invention is preferably less colored. In particular, if the coloration is expressed in terms of the transmittance of the glass, the wavelength (. lamda.) at which the spectral transmittance shows 70% in a sample having an optical glass of the present invention and a thickness of 10mm₇₀) Is 500nm or less, more preferably 480nm or less, still more preferably 460nm or less, most preferably 450nm or less. This makes it possible to improve the transparency of the glass in the visible light region by locating the absorption edge of the glass in the vicinity of the ultraviolet region, and thus the optical glass can be used as a material for an optical element such as a lens.

In particular, the optical glass according to the first embodiment of the present invention is preferably high in devitrification resistance. In particular, the optical glass of the present invention preferably has a low liquidus temperature of 1200 ℃ or less. More specifically, the upper limit of the liquidus temperature of the optical glass of the present invention is preferably 1200 ℃, more preferably 1150 ℃, and most preferably 1100 ℃. Thus, even when the molten glass is discharged at a lower temperature, the crystallization of the glass to be produced can be reduced, and therefore, the resistance to devitrification from the molten state to the time of forming the glass can be improved, and the influence on the optical characteristics of the optical element using the glass can be reduced. On the other hand, the lower limit of the liquidus temperature of the optical glass of the present invention is not particularly limited, but the liquidus temperature of the glass obtained by the present invention is usually about 500 ℃ or more, specifically about 550 ℃ or more, more specifically about 600 ℃ or more. The term "liquidus temperature" as used herein means the minimum temperature at which crystallization and devitrification do not occur in glass, which is measured by placing a granular glass sample crushed to a diameter of about 2mm on a platinum plate, placing the glass sample in a furnace having an inclined temperature (temperature inclined) of 800 to 1220 ℃ for 30 minutes, taking out the glass sample, cooling the glass sample, and observing the presence or absence of crystallization in the glass with a microscope having a magnification of 80 times.

Further, the optical glass according to the first embodiment of the present invention preferably has high acid resistance. Particularly, the chemical durability (acid resistance) measured by the glass powder method of JOGIS06-1999 is preferably 1 to 5, more preferably 1 to 4, and most preferably 1 to 3. Thus, when the optical glass is polished, the turbidity of the glass due to the acidic polishing liquid and the cleaning liquid can be reduced, and the polishing can be performed more easily. Here, "acid resistance" refers to the durability of glass against acid attack, and the acid resistance can be measured according to the Japanese optical glass society Specification "measuring method of chemical durability of optical glass" JOGIS 06-1999. Further, the phrase "chemical durability (acid resistance) measured by the powder method is on the order of 1 to 5" means that the chemical durability (acid resistance) measured according to JOGIS06-1999 is less than 2.20% by mass at a weight loss ratio (reduction ratio) of the sample mass before and after the measurement. Note that "1 grade" of chemical durability (acid resistance) means that the weight loss ratio of the sample mass before and after the measurement is less than 0.20 mass%, "2 grade" means that the weight loss ratio of the sample mass before and after the measurement is 0.20 mass% or more and less than 0.35 mass%, "3 grade" means that the weight loss ratio of the sample mass before and after the measurement is 0.35 mass% or more and less than 0.65 mass%, "4 grade" means that the weight loss ratio of the sample mass before and after the measurement is 0.65 mass% or more and less than 1.20 mass%, "5 grade" means that the weight loss ratio of the sample mass before and after the measurement is 1.20 mass% or more and less than 2.20 mass%, and "6 grade" means that the weight loss ratio of the sample mass before and after the measurement is 2.20 mass% or more.

On the other hand, the optical glass of the second embodiment of the present invention has a specific degree of abrasion. Specifically, the lower limit of the abrasion loss measured by the measuring method of "JOGIS 10-1994 method for measuring abrasion loss of optical glass" is preferably 100, more preferably 150, most preferably 200, and the upper limit thereof is preferably 400, more preferably 350, most preferably 300. By setting the abrasion degree to 100 or more, the glass can be easily polished during polishing, and therefore, the polishing efficiency can be improved and the polishing can be easily performed. On the other hand, when the abrasion degree is 400 or less, unnecessary loss and damage of the optical glass can be reduced, and therefore, the operation of polishing the optical glass can be facilitated, and the polishing can be easily performed.

In addition, the optical glass according to the second embodiment of the present invention preferably has a small average linear expansion coefficient (α). In particular, the optical glass of the present invention preferably has a low liquidus temperature, which is preferably 150X 10^-7K^-1Hereinafter, more preferably 120X 10^- ⁷K^-1The following, most preferably 100X 10^-7K^-1The following. Thus, when the optical glass is press-molded using a mold, expansion and contraction of the molded lens and the preform due to temperature change can be reduced. Therefore, particularly when cooling is performed after molding, it is possible to reduce the occurrence of a temperature gradient from the inside to the outside of the lens, which leads to the occurrence of indentations (depressions) or cracks in the lens.

On the other hand, the optical glasses of the third, fifth and sixth embodiments of the present invention have a glass transition point (Tg) of 700 ℃ or less. Thus, the glass softens at a lower temperature, and thus the glass can be press-formed at a lower temperature. In addition, the acidification of the die for precision press forming can be reduced, thereby prolonging the service life of the die. Therefore, the upper limit of the glass transition point (Tg) of the optical glass of the present invention is preferably 700 ℃, more preferably 680 ℃, more preferably 670 ℃, and most preferably 650 ℃. The lower limit of the glass transition point (Tg) of the optical glass of the present invention is not particularly limited, and the glass transition point (Tg) of the glass obtained according to the present invention is usually about 100 ℃ or higher, specifically about 150 ℃ or higher, more specifically about 200 ℃ or higher.

On the other hand, the optical glass of the fourth embodiment of the present invention preferably has high detergent resistance. In particular, the detergent resistance (PR) as measured by ISO test method detergent resistance (ISO 9689: 1990(E)) is preferably grade 1 to 3, more preferably grade 1 to 2, and most preferably grade 1. Thus, when the optical glass is washed after polishing, turbidity of the glass due to the aqueous cleaning solution can be reduced, and therefore, the optical glass can be more easily washed. The term "detergent resistance" as used herein means the superiority and inferiority of a yellowing state when the lens preform is washed before molding or when the molded lens is washed after being brought into contact with a pharmaceutical product or the like for washing for a certain period of time. The detergent resistance can be determined by the ISO test method detergent resistance (ISO 9689: 1990 (E)). The phrase "detergent resistance (PR) is of grade 1 to 3" means that the detergent resistance (PR) obtained according to ISO test method (ISO 9689: 1990(E)) is longer than 15 minutes, as long as it takes to attack a 0.1 μm glass layer.

[ preform and optical element ]

The optical glass of the present invention can be used for various optical elements and optical designs, and among them, it is particularly preferable to use a method of press molding (precision press molding or the like) from the optical glass of the present invention for producing optical elements such as lenses, prisms, mirrors, and the like. Thus, when used in an optical device such as a camera or a projector which transmits visible light through an optical element, high-definition and high-precision imaging characteristics can be realized, and the optical system of the optical device can be miniaturized. Here, since cutting and polishing can be omitted when producing an optical element made of the optical glass of the present invention, it is preferable to drop a molten glass from the outlet of an outlet pipe of platinum or the like into a preform for precision press molding such as a sphere, and perform precision press molding on the preform for precision press molding.

[ examples ]

Table 1 shows the glass compositions and refractive indices (n) of the glass compositions of the present invention examples (No. A1 to No. A7) and comparative examples (No. A1)_d) Abbe number (v)_d) Wavelength (lambda) at which the spectral transmittance is 70%₇₀) Liquid phase temperature, and chemical durability (acid resistance) measured by the powder method. Table 2 shows glass compositions and refractive indexes (n) of the glass compositions of the present invention examples (Nos. B1 to B5) and comparative example (No. B1)_d) Abbe number (v)_d) Wavelength (lambda) at which the spectral transmittance is 70%₇₀) Abrasion, and average linear expansion coefficient. Table 3 shows glass compositions and refractive indices (n) of examples (No. C1 to No. C5) and comparative examples (No. C1) of the present invention_d) Abbe number (v)_d) Wavelength (lambda) at which the spectral transmittance is 70%₇₀) And a glass transition point (Tg). Table 4 shows the glass compositions and refractive indices (n) of the glass compositions of the present invention examples (Nos. D1 to No. D5) and comparative example (No. D1)_d) Abbe number (v)_d) Wavelength (lambda) at which the spectral transmittance is 70%₇₀) And detergent resistance (PR) by ISO test method. Tables 5 to 7 show examples of the present invention (Nos. E1 to E14) and comparative examples (No. E1)Glass composition, refractive index (n)_d) Abbe number (v)_d) Wavelength (lambda) at which the spectral transmittance is 70%₇₀) And a glass transition point (Tg). Table 8 shows glass compositions and refractive indices (n) of the glass compositions of examples (No. F1 to No. F5) of the present invention and comparative example (No. F1)_d) Abbe number (v)_d) Wavelength (lambda) at which the spectral transmittance is 70%₇₀) And a glass transition point (Tg). It should be noted that the following examples are for illustrative purposes, and the present invention is not limited to these examples.

The optical glasses of the examples (No. A1 to No. A7, No. B1 to No. B5, No. C1 to No. C5, No. D1 to No. D5, No. E1 to No. E14, and No. F1 to No. F5) of the present invention and the glasses of the comparative examples (No. A1, No. B1, No. C1, No. D1, No. E1, and No. F1) were prepared by selecting high purity raw materials commonly used for optical glasses, such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, and metaphosphoric acid compounds, which correspond to the respective raw materials, weighing and mixing them uniformly according to the composition ratios of the examples and comparative examples shown in tables 1 to 8, placing them into a platinum crucible, melting and defoaming them in an electric furnace at a temperature range of 1000 to 1300 ℃ according to the melting difficulty of the glass composition, stirring and homogenizing and casting them under stirring and homogenizing to prepare the glass.

The refractive index (n) of the optical glasses of examples and the refractive index of the glasses of comparative examples_d) And Abbe number (v)_d) The measurement was carried out according to the Japanese optical Nitri Industrial Standard JOGIS 01-2003. As the glass used in the present measurement, a glass treated in an annealing furnace at a slow cooling rate of-25 ℃/hr as an annealing condition was used.

Further, the transmittance of the optical glass of the examples and the glass of the comparative example was measured in accordance with the japanese optical glass institute specification JOGIS 02. In the present invention, the presence or absence of coloring and the degree of coloring of the glass are determined by measuring the transmittance of the glass. Specifically, the spectral transmittance at a wavelength of 200 to 800nm of a polished article parallel to the opposing surface and having a thickness of 10. + -. 0.1mm is measured by JIS Z8722, and λ is determined₇₀(wavelength at a transmittance of 70%).

The liquidus temperatures of the optical glasses of examples (No. a1 to No. a7) and the glasses of comparative example (No. a1), which correspond to the optical glass of the first embodiment, were measured by the following methods: the crushed glass samples were placed on a platinum plate at intervals of 10mm, placed in a furnace having an inclined temperature of 800 ℃ to 1220 ℃ for 30 minutes, taken out, cooled, and then observed for the presence or absence of crystals in the glass samples by a microscope at a magnification of 80 times. At this time, the optical glass was pulverized into particles having a diameter of 2mm to obtain a sample.

Further, the acid resistance of the optical glasses of examples (No. A1 to No. A7) and the glass of comparative example (No. A1) was measured according to the Japanese society for optical and Nitri Specification "measuring method of chemical durability of optical glass" JOGIS 06-1999. That is, a glass sample crushed to 425 to 600 μm in particle size is put into a pycnometer and put into a platinum cage. The platinum cage was placed in a quartz glass round bottom flask containing 0.01N nitric acid in water and treated in a boiling water bath for 60 minutes. The weight loss ratio (% by mass) of the treated glass sample was calculated to be 1 grade when the weight loss ratio (% by mass) was less than 0.20, 2 grade when the weight loss ratio was less than 0.20 to 0.35, 3 grade when the weight loss ratio was less than 0.35 to 0.65, 4 grade when the weight loss ratio was less than 0.65 to 1.20, 5 grade when the weight loss ratio was less than 1.20 to 2.20, and 6 grade when the weight loss ratio was 2.20 or more. In this case, the smaller the number of grades, the more excellent the acid resistance of the glass.

On the other hand, the abrasion degrees of the optical glasses of examples (No. B1 to No. B5) and the glass of comparative example (No. B1) corresponding to the optical glass of the second embodiment were measured in accordance with "measuring method of abrasion degree of optical glass" JOGIS10-1994 ". That is, a sample of a glass corner plate having a size of 30X 10mm was placed on a cast iron plate (250 mm. phi.) horizontally rotated at 60 revolutions per minute at a position 80mm from the center of the plate, and a polishing liquid containing 10g of a #800 (average particle size 20 μm) polishing material (alumina A abrasive grains) added to 20ml of water was similarly supplied for 5 minutes while applying a load of 9.8N (1kgf) vertically, so that the sample was rubbed against the plate. The mass of the sample before and after grinding was measured to determine the loss mass of the sample. The loss mass of a standard sample specified by the Japan optical Nitri Industrial Association was determined in the same manner and calculated according to the following formula:

abrasion degree { (abrasion mass/specific gravity of test specimen)/(abrasion mass/specific gravity of standard test specimen) } × 100

The average linear expansion coefficients (. alpha.) of the optical glasses of examples (No. B1 to No. B5) and the glass of comparative example (No. B1) were determined from the average linear expansion coefficient at-30 ℃ to +70 ℃ in accordance with JOGIS08-2003, a method for measuring the thermal expansion of optical glasses, the Japan optical Nitri institute Specification.

On the other hand, the glass transition points (Tg) of the optical glasses of examples (No. c1 to No. c5, No. e1 to No. e14, and No. f1 to No. f5) and the glasses of comparative examples (No. c1, No. e1, and No. f1) corresponding to the optical glasses of the third, fifth, and sixth embodiments were determined by measurement using a lateral dilatometer (lateral dilatometer ). Wherein the sample is used for measurement

Glass with a length of 5mm and a temperature rise rate of 4 ℃/min.

On the other hand, the detergent resistance (PR) of the optical glasses of examples (No. d1 to No. d5) and the glass of comparative example (No. d1) corresponding to the optical glass of the fourth embodiment was measured according to the detergent resistance according to the ISO test method (ISO 9689: 1990 (E)). That is, a glass sample, which was a test piece and had been polished to 6 sides and had a thickness of 30mm × 30mm × 2mm, was hung with a platinum wire and placed in a purified aqueous solution of sodium tripolyphosphate heated to 50 ℃ and having a concentration of 0.01mol/L, and the solution was immersed for a predetermined period of time (15 minutes, 1 hour, 4 hours, 16 hours). After the dipping treatment, the mass reduction amount of the sample was measured, and the time required for etching a glass layer having a thickness of 0.1 μm was calculated from the following equation. However, the calculation was performed based on the shortest test time when the mass loss per sample was 1mg or more. The time required for etching a 0.1 μm glass layer was 1 grade for longer than 240 minutes, 2 grade for longer than 60 minutes and 240 minutes or less, 3 grade for 15 minutes to 60 minutes, and 4 grade for less than 15 minutes. In this case, the smaller the number of steps, the more excellent the detergent resistance of the glass.

t0.1＝te·d·S/((m1-m2)·100)

t 0.1: time (minutes) required for etching 0.1 μm glass layer

te: treatment time (minutes)

d: specific gravity of

S: surface area (cm) of the sample²)

m1-m 2: mass loss (mg) of sample

[ Table 1]

[ Table 2]

[ Table 3]

[ Table 4]

[ Table 5]

[ Table 6]

[ Table 7]

[ Table 8]

As shown in table 1, the optical glasses according to the examples of the present invention all had liquidus temperatures of 1200 ℃ or less, more specifically, less than 1120 ℃, and the liquidus temperatures were 500 ℃ or more. On the other hand, the liquidus temperature of the glass of comparative example (No. A1) was 1120 ℃. From this fact, it is understood that the optical glasses of examples (No. A1 to No. A7) of the present invention have a lower liquidus temperature and are less likely to cause devitrification than the glass of comparative example (No. A1).

As shown in table 2, the optical glasses of examples (No. b1 to No. b5) of the present invention all had a degree of abrasion of 400 or less, more specifically less than 300, and the degree of abrasion was 100 or more, more specifically 200 or more. On the other hand, the glass of comparative example (No. b1) had a degree of abrasion of 300. From this fact, it is understood that the optical glasses of examples (No. B1 to No. B5) of the present invention have a lower abrasion degree than the glass of comparative example (No. B1).

As shown in tables 3 and 5 to 8, the glass transition points (Tg) of the optical glasses of the examples of the present invention (No. C1 to No. C5, No. E1 to No. E14, No. F1 to No. F5) are all 700 ℃ or lower, more specifically 670 ℃ or lower.

In particular, the glass transition points (Tg) of the optical glasses of the examples (No. C1 to No. C5, No. F1 to No. F5) of the present invention are all 650 ℃ or lower. On the other hand, the glass of comparative examples (No. C1, No. F1) had a glass transition point (Tg) higher than 650 ℃. From this fact, it is understood that the optical glasses of examples (No. c1 to No. c5, No. f1 to No. f5) of the present invention have a lower glass transition point (Tg) than the glasses of comparative examples (No. c1, No. f1), and are easily softened at a lower heating temperature.

Furthermore, as shown in Table 4, the optical glasses of the examples (No. D1 to No. D5) of the present invention all have a detergent resistance (PR) of 1 to 3 grades, more specifically 1 grade, according to the ISO test method. On the other hand, the glass of comparative example (No. d1) had a detergent resistance (PR) of grade 3 according to the ISO test method. From this fact, it is understood that the optical glasses of examples (No. D1 to No. D5) of the present invention are superior to the glass of comparative example (No. D1) in the detergent resistance.

Further, λ of the optical glass of the embodiment of the present invention₇₀(wavelength at a transmittance of 70%) is 500nm or less, more specifically 492nm or less, and falls within a desired range.

In particular, λ of the optical glasses of examples (No. A1 to No. A7) of the present invention₇₀All of which are 450nm or less. On the other hand, λ of the glass of comparative example (No. A1)₇₀Greater than 450 nm. From this fact, it is found that the optical glasses of examples (No. A1 to No. A7) of the present invention are less colored than the glass of comparative example (No. A1).

Further, λ of the optical glasses of the examples (No. B1 to No. B5) of the present invention₇₀(wavelength at a transmittance of 70%) is 480nm or less. On the other hand, λ of the glass of comparative example (No. B1)₇₀Greater than 480 nm. From this fact, it is found that the optical glasses of examples (No. B1 to No. B5) of the present invention are less colored than the glass of comparative example (No. B1).

Further, λ of the optical glass of examples (No. C1 to No. C5, No. D1 to No. D5) of the present invention₇₀(wavelength at a transmittance of 70%) of 450nm or less. On the other hand, λ of the glass of comparative example (No. D1)₇₀Is 500 nm. From this fact, it is found that the optical glasses of examples (No. D1 to No. D5) of the present invention are less colored than the glass of comparative example (No. D1).

In addition, λ of the optical glasses of examples (No. F1 to No. F5)₇₀(wavelength at a transmittance of 70%) is 470nm or less. On the other hand, λ of the glass of comparative example (No. F1)₇₀Greater than 470 nm. From this fact, it is found that the optical glasses of examples (No. F1 to No. F5) of the present invention are less likely to be colored than the glass of comparative example (No. F1).

Further, the refractive index (n) of the optical glass of the embodiment of the present invention_d) 1.70 or more, more specifically 1.80 or more, and the refractive index (n)_d) Is 2.20 or less, more specifically 2.10 or less, and falls within a desired range. In particular, the refractive index (n) of the optical glasses of examples (No. C1 to No. C5)_d) Is 1.86 or more. The refractive index (n) of the optical glasses of examples (No. D1 to No. D5)_d) Is 1.84 or more. Further, examples (No. E1 to No)E14) refractive index (n) of the optical glass_d) Is 1.90 or more. Further, the refractive index (n) of the optical glasses of examples (No. F1 to No. F5)_d) Is 1.92 or more. On the other hand, the refractive index (n) of the optical glass of examples (No. B1 to No. B5, No. C1 to No. C5, No. D1 to No. D5, No. E1 to No. E14, No. F1 to No. F5) of the present invention_d) All are 2.00 or less.

Further, the Abbe number (v) of the optical glass of the example of the present invention_d) All of them are 10 or more, more specifically 15 or more, and the Abbe number (v) thereof_d) Is 25 or less, and falls within a desired range. In particular, the Abbe number (v) of the optical glasses of examples (No. B1 to No. B5) of the present invention_d) All are above 17. On the other hand, the Abbe numbers (v) of the optical glasses of the examples (No. B1 to No. B5, No. D1 to No. D5) of the present invention_d) Both are 23 or less. Further, the Abbe numbers (v) of the optical glasses of examples (No. C1 to No. C5)_d) Is 24 or less.

In particular, the Abbe numbers (v) of the optical glasses of examples (No. E1 to No. E14, No. F1 to No. F5)_d) Is 20 or less. On the other hand, the Abbe number (v) of the glass of comparative example (No. E1, No. F1)_d) Greater than 20. From this fact, it is understood that the optical glasses of the examples (No. E1 to No. E14, No. F1 to No. F5) of the present invention have higher dispersion and lower Abbe number (v) than those of the glasses of the comparative examples (No. E1, No. F1)_d)。

The chemical durability (acid resistance) of the optical glass of the present invention examples (No. a1 to No. a7) as measured by the powder method is on a1 to 5 scale, more specifically on a1 to 2 scale. On the other hand, the glass of comparative example (No. a1) had a chemical durability (acid resistance) of 4 grade as measured by the powder method. From this fact, it is understood that the optical glasses of examples (No. A1 to No. A7) of the present invention are superior in acid resistance to the glass of comparative example (No. A1).

In addition, the average linear expansion coefficients (. alpha.) of the optical glasses of the examples (No. B1 to No. B5) of the present invention were all 150X 10^-7K^-1Hereinafter, more specifically, 100 × 10^-7K^-1The following. On the other hand, the glass of comparative example (No. B1) had an average linear expansion coefficient (. alpha.) of more than 100X 10^-7K^-1The following. ByIt is understood that the optical glasses of examples (No. B1 to No. B5) of the present invention have a smaller average linear expansion coefficient (. alpha.) than the glass of comparative example (No. B1).

The optical glass of examples (No. a1 to No. a7) of the present invention was cut and polished to form a preform, the preform was press-molded while being placed in a mold and heated to soften the preform, and the obtained molded body was polished, whereby the optical glass could be stably processed into various lens shapes.

The optical glass of examples (No. b1 to No. b5) of the present invention was put in a mold, and the optical glass was press-molded while being heated and softened, and the obtained molded body was polished, whereby the optical glass could be stably processed into various lens shapes.

Further, by forming a precision press molding preform using the optical glass of the examples (No. c1 to No. c5, No. e1 to No. e14, and No. f1 to No. f5) of the present invention and performing precision press molding on the precision press molding preform, the optical glass can be stably processed into various lens shapes.

Further, the optical glass of examples (No. d1 to No. d5) of the present invention was cut and polished to form a preform, the preform was press-molded while being placed in a mold and heated to be softened, the obtained molded body was polished, and the polished glass was washed, whereby the optical glass could be stably processed into various lens shapes.

As a result, the refractive index (n) of the optical glass of the examples of the present invention was found to be_d) In the desired range while having high dispersion (low abbe number v)_d) And has high transparency to light having a wavelength in the visible light region.

In particular, it is found that the optical glasses of examples (No. a1 to No. a7) of the present invention have high devitrification resistance when formed into a glass, and are less likely to cause clouding in the glass when the glass is used as a grinding rod.

Further, it is found that the optical glasses of the examples (nos. b1 to b5) of the present invention are easy to be polished, and expansion or contraction is hardly caused even if the glass undergoes a temperature change.

Further, it is found that the optical glasses of the examples (No. C1 to No. C5, No. E1 to No. E14, No. F1 to No. F5) of the present invention are easily softened at low temperature.

Further, it is understood that the optical glasses of the examples (nos. d1 to d5) of the present invention are easily washed when producing a preform material or an optical element.

The present invention has been described in detail for the purpose of illustration, and it is to be understood that this embodiment is for the purpose of illustration only, and that various changes and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention.

Claims

1. An optical glass comprising 10.0 to 33.0% by mass of P in terms of oxide content based on the total mass of the glass₂O₅Ingredients (A) and (B),

30.0% to 58.0% Nb₂O₅Ingredients (A) and (B),

5.5% to 12.0% Na₂A component (C) of an oxygen-containing compound,

SiO₂the content of the component is less than 1.5%,

the content of BaO component is less than 10.0 percent,

Bi₂O₃the content of the components is less than 5.0 percent,

Ta₂O₅the content of the component (A) is 4.0% or less,

Sb₂O₃the content of the component (A) is less than 0.01%,

total mass, mass and Li of glass relative to oxide conversion composition₂O+Na₂O+K₂O is 10.2% to 20.0%.

2. The optical glass according to claim 1, wherein the spectral transmittance of the optical glass is 70% of the wavelength (λ)₇₀) Is 500nm or less, and has a liquidus temperature of 500 ℃ to 1200 ℃.

3. The optical glass as claimed in claim 1, which has an abrasion degree of 100 or more and 400 or less.

4. An optical glass as defined in claim 1 having a scrub resistance (PR) of 1 to 3 class according to ISO test method.

5. The optical glass as claimed in claim 1, which contains Li₂O component and Na₂Component O and K₂At least one of the O components is an essential component, and has a glass transition point (Tg) of 700 ℃ or lower.

6. The optical glass according to claim 1, wherein TiO is contained in an amount of mass% with respect to the total mass of the glass in terms of oxide of the composition₂The content of the component is below 30.0%.

7. The optical glass according to claim 1, wherein the TiO content is in mass% with respect to the total mass of the glass in terms of oxide-converted composition₂The content of the component (B) is less than 10.0%, and the glass transition point (Tg) is 700 ℃ or lower.

8. The optical glass according to claim 1, wherein the TiO content is 10.0% by mass or more and 30.0% by mass or less based on the total mass of the glass in terms of oxide₂Component (b) has a glass transition point (Tg) of 700 ℃ or lower.

9. The optical glass according to claim 1, wherein the glass comprises, in mass%, based on the total mass of the glass in terms of oxides:

WO₃0 to 20.0% of the component (A).

10. The optical glass according to claim 1, wherein the glass comprises, in mass%, based on the total mass of the glass in terms of oxides:

Li₂0 to 20.0% of O component and/or

K₂0 to 20.0% of an O component.

11. The optical glass as claimed in claim 10, which contains Li₂O component and Na₂O component and K₂More than 2 of the O component.

12. The optical glass according to claim 1, wherein the glass comprises, in mass%, based on the total mass of the glass in terms of oxides:

MgO component 0-5.0% and/or

CaO content of 0 to 10.0% and/or

0 to 10.0% of SrO.

13. An optical glass according to claim 12, wherein the sum of the mass and the mass of MgO + CaO + SrO + BaO is 30.0% or less with respect to the total mass of the glass in terms of oxides.

14. The optical glass according to claim 1, wherein the glass comprises, in mass%, based on the total mass of the glass in terms of oxides:

Y₂O₃0 to 10.0% of the component(s) and/or

La₂O₃0 to 10.0% of the component(s) and/or

Gd₂O₃0 to 10.0% of the component (A).

15. The optical glass according to claim 14, wherein the sum of the mass and the Y is the total mass of the glass in terms of oxide converted composition₂O₃+La₂O₃+Gd₂O₃Is 20.0% or less.

16. The optical glass according to claim 1, wherein the glass comprises, in mass%, based on the total mass of the glass in terms of oxides:

B₂O₃0 to 10.0% of the component(s) and/or

GeO₂0 to 10.0% of the component(s) and/or

ZrO₂0 to 10.0% of the component(s) and/or

0 to 10.0% of ZnO and/or

Al₂O₃0 to 10.0% of the component (A).

17. The optical glass according to claim 1, which has a refractive index (nd) of 1.70 or more and 2.20 or less and has an Abbe's number (nd) of 10 or more and 25 or less.

18. The optical glass according to claim 1, wherein the spectral transmittance of the optical glass is 70% of the wavelength (λ)₇₀) Is 500nm or less.

19. An optical element made of the optical glass of any one of claims 1 to 18.

20. A preform for precision press molding, which is made of the optical glass according to any one of claims 1 to 18.