TW202404918A - Optical glass and optical component having a low glass transition temperature and excellent thermal stability - Google Patents

Abstract

The present invention provides an optical glass having a low glass transition temperature and excellent thermal stability. In the glass composition expressed in cation% of the optical glass, the Li<SP>+<SP> content is more than 0.0 cation% and 48.0% or less, the Na<SP>+<SP> content is more than 0.0 cation% and 35.0% or less, and the K<SP>+<SP> content is more than 0.0 cation% and 30.0% or less, the total content (Al<SP>3+<SP> + P<SP>5+<SP>) is 38.0% to 70.0%, the total content of Li<SP>+<SP>, Na<SP>+<SP>, K<SP>+<SP> and Cs<SP>+<SP> is designated as R<SP>+<SP> and the total content of Be<SP>2+<SP>, Mg<SP>2+<SP>, Ca<SP>2+<SP>, Sr<SP>2+<SP> and Ba<SP>2+<SP> are designated as R<SP>2+<SP>, the cation ratio (R<SP>+<SP>/(Al<SP>3+<SP> + P<SP>5+<SP>)) is 0.93 or more, (Li<SP>+<SP>/(R<SP>+<SP> + R<SP>2+<SP>)) is 0.29 or more, ((Li<SP>+<SP> + K<SP>+<SP>)/(Al<SP>3+<SP> + P<SP>5+<SP>)) is 0.56 or more, and (R<SP>2+<SP>/(Al<SP>3+<SP> + R<SP>2+<SP>)) is 0.37 or less. The optical glass of this invention has the following glass composition as expressed in anion%: the O<SP>2-<SP> content is 83.0% or less, the F<SP>-<SP> content is 19.0% or more, and the external transmittance at a wavelength of 500 nm to 1000 nm is 80% or more when converted to a thickness of 10.0 mm.

Description

Optical glass and optical components

The present invention relates to optical glass and optical components.

For example, Patent Document 1 discloses optical glass with a low glass transition temperature. [Prior art documents] [Patent Document]

Patent document 1: WO2003/037813

[Problem to be solved by the invention]

Glass with a low glass transition temperature can be formed at low temperatures. It is preferable to be able to mold at a low temperature from the viewpoint of less deterioration of the molding die due to heating and the ability to use a low-heat-resistant, inexpensive molding die. However, as a result of research conducted by the present inventors on optical glass with a low glass transition temperature, it was found that further improvements in thermal stability are expected.

An object of one aspect of the present invention is to provide optical glass with a low glass transition temperature and excellent thermal stability. [Means used to solve problems]

One aspect of the present invention relates to an optical glass in which the Li ⁺ content exceeds 0.0 cation % and is 48.0 cation % or less, and the Na ⁺ content exceeds 0.0 cation % and is 35.0 cation % or less in the glass composition expressed as cation %, K The ⁺ content exceeds 0.0 cation % and is 30.0 cation % or less, and the total content of Al ³⁺ and P ⁵⁺ (Al ³⁺ +P ⁵⁺ ) is 38.0 cation % or more and 70.0 cation % or less, where Li ⁺ , Na The total content of ⁺ , K ⁺ and Cs ⁺ is set to R ⁺ , the total content of Be ²⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ is set to R ²⁺ , R ⁺ is relative to Al ³ The cation ratio of the total content of ⁺ and P ⁵⁺ (R ⁺ /(Al ³⁺ +P ⁵⁺ )) is 0.93 or more, and the cation ratio of the total content of Li ⁺ to the total content of R ⁺ and R ²⁺ (Li ⁺ /( R ⁺ +R ²⁺ )) is 0.29 or more, and the cation ratio of the total content of Li ⁺ and K ⁺ to the total content of Al ³⁺ and P ⁵⁺ ((Li ⁺ +K ⁺ )/(Al ³⁺ +P ⁵⁺ )) is 0.56 or more, and the cation ratio of R ²⁺ to the total of Al ³⁺ content and R ²⁺ (R ²⁺ /(Al ³⁺ +R ²⁺ )) is 0.37 or less, expressed as anion % In the glass composition, the O ^{2 -} content is 83.0 anion % or less, the F ^- content is 19.0 anion % or more, and the external transmittance of the optical glass at the wavelength of 500 nm to 1000 nm is more than 80% when converted to a thickness of 10.0 mm.

By having the above-mentioned glass composition, the optical glass can have a low glass transition temperature and exhibit excellent thermal stability. [Effects of the invention]

According to one aspect of the present invention, optical glass having a low glass transition temperature and excellent thermal stability can be provided. In addition, according to one embodiment of the present invention, an optical element formed of such optical glass can be provided.

[Optical Glass] In the present invention and this specification, unless otherwise specified, the content and total content of cationic components are expressed in cation %, and unless otherwise specified, the content and total content of anionic components are expressed in anion %. Here, "% of cations" is a value calculated as ""(number of cations of interest/total number of cations in the glass component)×100" and represents the amount of cations of interest relative to the total amount of cation components. mole percentage. In addition, "% of anions" is a value calculated as "(number of anions of interest/total number of anions in the glass component) × 100" and represents the amount of anions of interest relative to the total amount of anion components. Mol%. The molar ratio of the contents between the cationic components is equal to the ratio of the contents expressed in % cations of the cationic components of interest. The content of each component can be quantified by known methods, such as inductively coupled plasma optical emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), ion chromatography, and the like. Cationic components are represented by, for example, Al ³⁺ and P ⁵⁺ , and the valence of the cationic component (for example, the valence of Al ³⁺ is +3, and the valence of P ⁵⁺ is +5) is determined by convention. The value is the same as expressing Al, P, etc. as Al ₂ O ₃ , P ₂ O ₅ , etc. on an oxide basis. Regarding the component represented by _{Am On} on an oxide basis (A represents a cation, O represents oxygen, m and n are stoichiometrically determined integers), the cation A is represented by As ⁺ , where s=2n/m. Therefore, for example, when analyzing and quantifying the glass composition, it is not necessary to analyze the valence of the cationic component. The above points are the same for anionic components. When analyzing and quantifying the glass composition, the valence of the anionic component does not need to be analyzed. In addition, in the present invention and this specification, the content of a constituent component is 0.0%, 0.00%, does not contain, or is not introduced, which means that the constituent component is not substantially included, and the content of the constituent component is below the impurity level. The impurity level Below means, for example, less than 0.01%.

In the present invention and this specification, "thermal stability" refers to the degree to which crystals are less likely to precipitate when molten glass solidifies.

Hereinafter, the glass transition temperature may be expressed as Tg.

Hereinafter, the above-mentioned optical glass (sometimes simply referred to as "glass") will be described in more detail.

<Glass composition> Hereinafter, the glass composition expressed in cation % of the above-mentioned optical glass will be described. In the present invention and this specification, the total content of Li ⁺ , Na ⁺ , K ⁺ and Cs ⁺ is also referred to as "R ⁺ "", and Be ²⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and The total content of Ba ²⁺ is expressed as "R ²⁺ ".

From the viewpoint of increasing the refractive index while maintaining low dispersion, and from the viewpoint of lowering the Tg of the glass and improving the meltability, the Li ⁺ content exceeds 0.0%, preferably 2.0% or more, 4.0% or more, 6.0% or more, 8.0 The order of more than %, more than 10.0%, more than 11.0%, more than 12.0%, more than 13.0%, more than 14.0%, more than 15.0%, more than 16.0%, more than 17.0% is better. In addition, from the viewpoint of improving the thermal stability of the glass and maintaining the thermal stability of the glass, the Li ⁺ content is 48.0 cation % or less, preferably 47.0% or less, 46.0% or less, 45.0% or less, 44.0% or less, 43.0% or less. The order of % or less, 42.0% or less, 41.0% or less, and 40.0% or less is better.

From the viewpoint of maintaining the refractive index, maintaining low dispersion, lowering the Tg of the glass, improving meltability, and lowering the specific gravity, the Na ⁺ content exceeds 0.0 cation %, preferably 1.0% or more, 2.0% or more, and 3.0% or more. The order of , 4.0% or more, and 5.0% or more is better. In addition, from the viewpoint of maintaining the thermal stability of the glass, the Na ⁺ content is 35.0 cation % or less, preferably 34.0% or less, 33.0% or less, 32.0% or less, 31.0% or less, 30.0% or less, 29.0% or less, The order of 28.0% or less, 27.0% or less, and 26.0% or less is better.

From the viewpoint of maintaining the refractive index, maintaining low dispersion, lowering the Tg of the glass, and improving the meltability, the K ⁺ content exceeds 0.0 cation %, preferably 1.0% or more, 2.0% or more, 3.0% or more, or 4.0% or more. order is better. In addition, from the viewpoint of maintaining the thermal stability of the glass, the K ⁺ content is 30.0 cation % or less, preferably 29.0% or less, 28.0% or less, 27.0% or less, 26.0% or less, 25.0% or less, 24.0% or less, The order of 23.0% or less, 22.0% or less, 21.0% or less, 20.0% or less, 19.0% or less, and 18.0% or less is better.

The Cs ⁺ content may be 0.0%, or more than 0.0%, or more than 0.0%. From the viewpoint of further lowering the Tg of the glass and improving the meltability of the glass, the Cs ⁺ content may be 0.0% or more, more preferably 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, or 0.5% or more. , 0.6% or more is better. In addition, from the viewpoint of further improving the thermal stability of the glass and suppressing a decrease in chemical durability, the Cs ⁺ content is preferably 10.0% or less, 8.0% or less, 6.0% or less, 4.0% or less, 2.0% or less, or 1.5% or less. , the order below 1.0% is better.

From the viewpoint of maintaining low dispersion, further lowering the Tg and specific gravity of the glass, and lowering the liquidus temperature, the total content R ⁺ of Li ⁺ , Na ⁺ , K ⁺ and Cs ⁺ is preferably 5.0% or more, and more preferably The best is more than 10.0%, more than 15.0%, more than 20.0%, more than 23.0%, more than 25.0%, more than 28.0%, more than 30.0%, more than 33.0%, more than 35.0%, more than 37.0%, more than 40.0%, more than 41.0% , 42.0% or more, 43.0% or more, 44.0% or more, 45.0% or more, 46.0% or more, 47.0% or more, 48.0% or more are further preferred. In addition, from the viewpoint of maintaining low dispersion, maintaining the thermal stability of the glass, and suppressing a decrease in chemical durability, the total content R ⁺ of Li ⁺ , Na ⁺ , K ⁺ and Cs ⁺ is preferably 65.0% or less, preferably 64.0% The order of below, below 63.0%, below 62.0%, below 61.0%, below 60.0%, below 59.0% is better.

From the viewpoint of maintaining the thermal stability of the glass, the total content of Al ³⁺ and P ⁵⁺ (Al ³⁺ +P ⁵⁺ ) is 38.0 cation % or more, preferably 38.1% or more, and 38.2% or more, 38.3% The order of above, above 38.4%, above 38.5%, above 38.6%, above 38.7%, above 38.8%, above 38.9%, above 39.0% is better. In addition, from the viewpoint of suppressing an increase in Tg, the total content of Al ³⁺ and P ⁵⁺ (Al ³⁺ +P ⁵⁺ ) is 70.0 cation % or less, preferably 65.0% or less, and 60.0% or less, 59.0% or less. The order of below, below 58.0%, below 57.0%, below 56.0%, below 55.0%, below 54.0%, below 53.0%, below 52.0%, below 51.0%, below 50.0% is better.

From the viewpoint of increasing the refractive index and maintaining low dispersion, and from the viewpoint of further improving the thermal stability of the glass and maintaining chemical durability, the Al ³⁺ content is preferably more than 0.0%, more preferably 1.0% or more, and more preferably 2.0% or more. , 3.0% or more, 4.0% or more, 5.0% or more, 6.0% or more, 7.0% or more, 8.0% or more, 9.0% or more, 10.0% or more, 11.0% or more are further preferred. In addition, from the viewpoint of further suppressing an increase in Tg, the Al ³⁺ content is preferably 30.0% or less, more preferably 29.0% or less, 28.0% or less, 27.0% or less, 26.0% or less, 25.0% or less, 24.0% or less. The order of below, 23.0% or below, 22.0% or below, 21.0% or below, 20.0% or below, 19.0% or below, and 18.0% or below is further preferred.

From the viewpoint of maintaining low dispersion and further improving the thermal stability of the glass, the P ⁵⁺ content is preferably 5.0% or more, more preferably 7.0% or more, and 9.0% or more, 11.0% or more, 13.0% or more, 14.0% The order of above, above 15.0%, above 16.0%, above 17.0%, above 18.0%, above 19.0%, above 20.0%, above 21.0%, above 22.0%, and above 23.0% is further preferred. In addition, from the viewpoint of maintaining the refractive index, further improving the thermal stability of the glass, and suppressing a decrease in chemical durability, the P ⁵⁺ content is preferably 50.0% or less, more preferably 48.0% or less, and 46.0% or less, 44.0% or less. % or less, 42.0% or less, 40.0% or less, 38.0% or less, 37.0% or less, 36.0% or less, 35.0% or less, 34.0% or less, 33.0% or less, and 32.0% or less are more preferred in this order.

From the viewpoint of lowering the Tg of the glass and improving the meltability of the glass, the cation ratio of R ⁺ to the total content of Al ³⁺ and P ⁵⁺ (R ⁺ /(Al ³⁺ +P ⁵⁺ )) is 0.93 or more , preferably 0.94 or more, more preferably 0.95 or more, and 0.96 or more in this order. In addition, from the viewpoint of maintaining the thermal stability of the glass, the cation ratio (R ⁺ /(Al ³⁺ +P ⁵⁺ )) is preferably 3.00 or less, more preferably 2.75 or less, and 2.50 or less, 2.25 or less, or 2.00 or less. The order of , 1.90 or less, 1.80 or less, 1.70 or less, 1.65 or less, 1.60 or less, 1.55 or less, 1.50 or less, 1.45 or less, and 1.40 or less is even better.

From the viewpoint of increasing the refractive index, lowering the Tg of the glass, and improving the meltability of the glass, the cation ratio of the Li ⁺ content to the total of R ⁺ and R ²⁺ (Li ⁺ /(R ⁺ +R ²⁺ )) It is 0.29 or more, preferably 0.30 or more, more preferably 0.31 or more, and 0.32 or more in this order. In addition, from the viewpoint of maintaining the thermal stability of the glass, the cation ratio (Li ⁺ /(R ⁺ +R ²⁺ )) is preferably 1.00 or less, more preferably 0.95 or less, 0.94 or less, 0.93 or less, 0.92 or less, The order of 0.91 or less, 0.90 or less, 0.89 or less, 0.88 or less, 0.87 or less, 0.86 or less, 0.85 or less, 0.84 or less, and 0.83 or less is better.

From the viewpoint of further lowering the Tg of the glass, improving the meltability of the glass, and lowering the specific gravity, the cation ratio of the total content of Li ⁺ and K ⁺ to the total content of Al ³⁺ and P ⁵⁺ ((Li ⁺ +K ⁺ )/(Al ³⁺ +P ⁵⁺ )) is 0.56 or more, preferably 0.57 or more, in the order of 0.58 or more, 0.59 or more, 0.60 or more, 0.61 or more, 0.62 or more, 0.63 or more, 0.64 or more, and 0.65 or more Better. In addition, from the viewpoint of maintaining the refractive index and maintaining thermal stability, the cation ratio ((Li ⁺ +K ⁺ )/(Al ³⁺ +P ⁵⁺ )) is preferably 2.00 or less, more preferably 1.80 or less, and 1.70 The order of below, 1.60 below, 1.50 below, 1.40 below, 1.30 below, 1.20 below, and 1.10 below is even more preferable.

From the viewpoint of maintaining the thermal stability of the glass, the cation ratio of R ²⁺ to the total of the Al ³⁺ content and R ²⁺ (R ²⁺ /(Al ³⁺ +R ²⁺ )) is preferably 0.37 or less. It is 0.36 or less, preferably 0.35 or less, 0.34 or less, 0.33 or less, 0.32 or less, 0.31 or less, and 0.30 or less in this order. In addition, the cation ratio (R ²⁺ /(Al ³⁺ +R ²⁺ )) may be 0.00, or may be 0.00 or more or exceed 0.00. From the viewpoint of lowering the liquidus temperature and increasing the refractive index, the cation ratio (R ²⁺ /(Al ³⁺ +R ²⁺ )) is preferably 0.00 or more, more preferably 0.01 or more, and 0.02 or more, or 0.03 or more. The order is even better.

The total content R ²⁺ of Be ²⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ may be 0.0%, 0.0% or more, or more than 0.0%. From the viewpoint of maintaining the refractive index, maintaining low dispersion, suppressing an increase in Tg, and maintaining the thermal stability of the glass, the total content R ²⁺ is preferably 20.0% or less, more preferably 19.0% or less, and 18.0% or less. The order of 17.0% or less, 16.0% or less, 15.0% or less, 14.0% or less, 13.0% or less, 12.0% or less, 11.0% or less, 10.0% or less, 9.0% or less, 8.0% or less, and 7.0% or less is further preferred.

The Be ²⁺ content may be 0.0%, more than 0.0%, or more than 0.0%. From the viewpoint of maintaining the refractive index, maintaining low dispersion, suppressing an increase in Tg, and maintaining the thermal stability of the glass, the Be ²⁺ content is preferably 15.0% or less, more preferably 10.0% or less, and 5.0% or less, 2.5 % or less, 1.5% or less, 1.0% or less, and 0.5% or less are further preferred in this order. The Mg ²⁺ content may be 0.0%, more than 0.0%, or more than 0.0%. From the viewpoint of maintaining the refractive index, maintaining low dispersion, suppressing an increase in Tg, and maintaining the thermal stability of the glass, the Mg ²⁺ content is preferably 15.0% or less, more preferably 14.0% or less, and 13.0% or less, 12.0% or less. The order of below, 11.0% or below, 10.0% or below, 9.0% or below, 8.0% or below, 7.0% or below, and 6.0% or below is further preferred. The Ca ²⁺ content can be 0.0%, more than 0.0%, or more than 0.0%. From the viewpoint of maintaining the refractive index, maintaining low dispersion, suppressing an increase in Tg, and maintaining the thermal stability of the glass, the Ca ²⁺ content is preferably 10.0% or less, more preferably 9.0% or less, and 8.0% or less, 7.0% or less. The order of below, 6.0% or below, and 5.0% or below is even more preferable. The Sr ²⁺ content may be 0.0%, more than 0.0%, or more than 0.0%. From the viewpoint of maintaining the refractive index, maintaining low dispersion, suppressing an increase in Tg, and maintaining the thermal stability of the glass, the Sr ²⁺ content is preferably 10.0% or less, more preferably 9.0% or less, and 8.0% or less, 7.0% or less. The order of below, 6.0% or below, 5.0% or below, and 4.0% or below is further preferred. The Ba ²⁺ content may be 0.0%, more than 0.0%, or more than 0.0%. From the viewpoint of maintaining the refractive index, maintaining low dispersion, suppressing an increase in Tg, and maintaining the thermal stability of the glass, the Ba ²⁺ content is preferably 10.0% or less, more preferably 9.0% or less, and 8.0% or less, 7.0% or less. The order of below, 6.0% or below, 5.0% or below, 4.0% or below, 3.0% or below, and 2.0% or below is more preferable.

The Zn ²⁺ content may be 0.0%, more than 0.0%, or more than 0.0%. Zn ²⁺ plays a role in maintaining the refractive index and improving thermal stability, but if contained in excess, dispersion tends to increase. From the above point of view, the Zn ²⁺ content is preferably 20.0% or less, more preferably 19.0% or less, 18.0% or less, 17.0% or less, 16.0% or less, 15.0% or less, 14.0% or less, 13.0% or less, 12.0% The order of below, 11.0% or below, 10.0% or below, 9.0% or below, 8.0% or below, 7.0% or below, 6.0% or below, and 5.0% or below is further preferred.

The Zr ⁴⁺ content can be 0.0%, more than 0.0%, or more than 0.0%. Zr ⁴⁺ is a component that increases the refractive index, but if contained in excess, dispersion tends to increase and Tg tends to increase. From the above point of view, the Zr ⁴⁺ content is preferably 10.0% or less, more preferably 9.0% or less, 8.0% or less, 7.0% or less, 6.0% or less, 5.0% or less, 4.0% or less, 3.0% or less, 2.0% The following order is even better.

The Nb ⁵⁺ content may be 0.0%, more than 0.0%, or more than 0.0%. Nb ⁵⁺ is a component that increases the refractive index, but if contained in excess, dispersion tends to increase and Tg tends to increase. From the above point of view, the Nb ⁵⁺ content is preferably 10.0% or less, more preferably 9.0% or less, 8.0% or less, 7.0% or less, 6.0% or less, 5.0% or less, 4.0% or less, 3.0% or less, 2.0% The following order is even better.

The Ti ⁴⁺ content can be 0.0%, more than 0.0%, or more than 0.0%. Ti ⁴⁺ increases the refractive index, but if contained excessively, dispersion tends to increase and Tg tends to increase. From the above point of view, the Ti ⁴⁺ content is preferably 10.0% or less, more preferably 9.0% or less, 8.0% or less, 7.0% or less, 6.0% or less, 5.0% or less, 4.0% or less, 3.0% or less, 2.0% The following order is even better.

The W ⁶⁺ content may be 0.0%, more than 0.0%, or more than 0.0%. W ⁶⁺ is a component that increases the refractive index, but if contained in excess, dispersion tends to increase and Tg tends to increase. From the above point of view, the W ⁶⁺ content is preferably 10.0% or less, more preferably 9.0% or less, 8.0% or less, 7.0% or less, 6.0% or less, 5.0% or less, 4.0% or less, 3.0% or less, 2.0% The following order is even better.

The cation ratio (( ^{Li + +} Na ^{+ )} /(Li ⁺ +K ⁺ )) of the total content of Li ⁺ and Na ⁺ relative to the total content of Li + and K + can exceed 0.00, thereby maintaining the thermal stability of the glass. From the viewpoint of further lowering Tg and improving the meltability of the glass, it is preferably 0.50 or more, more preferably 0.55 or more, and 0.60 or more, 0.65 or more, 0.66 or more, 0.67 or more, 0.68 or more, 0.69 or more, 0.70 or more, 0.71 or more The order of , 0.72 or more, 0.73 or more, 0.74 or more, 0.75 or more, 0.76 or more, 0.77 or more, 0.78 or more, 0.79 or more, and 0.80 or more is more preferable. In addition, from the viewpoint of maintaining the thermal stability of the glass, further lowering Tg, and improving the meltability of the glass, the cation ratio ((Li ⁺ +Na ⁺ )/(Li ⁺ +K ⁺ )) is preferably 2.05 or less. More preferably, it is less than 2.00, less than 1.95, less than 1.90, less than 1.85, less than 1.80, less than 1.75, less than 1.70, less than 1.65, less than 1.64, less than 1.63, less than 1.62, less than 1.61, less than 1.60, less than 1.59, less than 1.58, less than 1.57 The order of below, 1.56 below, 1.55 below, 1.54 below, 1.53 below, 1.52 below, 1.51 below, and 1.50 below is even more preferable.

The cation ratio ((Na ^{+ + K + )} /(Li ⁺ +K ⁺ )) of the total content of Na ⁺ and K ⁺ relative to the total content of Li + and K + can exceed 0.00, thereby maintaining the thermal stability of the glass. From the viewpoint of further lowering Tg and improving the meltability of the glass, it is preferably 0.05 or more, more preferably 0.07 or more, and 0.09 or more, 0.11 or more, 0.13 or more, 0.15 or more, 0.16 or more, 0.17 or more, 0.18 or more, 0.19 or more , the order above 0.20 is even better. In addition, from the viewpoint of maintaining the thermal stability of the glass, further lowering Tg, and improving the meltability of the glass, the cation ratio ((Na ⁺ +K ⁺ )/(Li ⁺ +K ⁺ )) is preferably 2.00 or less, or more The best is below 1.95, below 1.90, below 1.85, below 1.80, below 1.75, below 1.70, below 1.55, below 1.50, below 1.45, below 1.40, below 1.39, below 1.38, below 1.37, below 1.36, below 1.35, below 1.34 The order of , 1.33 or less, 1.32 or less, 1.31 or less, and 1.30 or less is even better.

The cation ratio of the Li ⁺ content to the total content of Li ⁺ and Na ⁺ (Li ⁺ /(Li ⁺ +Na ⁺ )) can exceed 0.00, thereby maintaining the thermal stability of the glass, further lowering Tg, and improving the meltability of the glass. From the viewpoint of The order of , 0.39 or more, and 0.40 or more is even better. In addition, from the viewpoint of maintaining the thermal stability of the glass, further lowering Tg, and improving the meltability of the glass, the cation ratio (Li ⁺ /(Li ⁺ +Na ⁺ )) is preferably 1.00 or less, more preferably 0.98 or less. The order of 0.96 or less, 0.94 or less, 0.93 or less, 0.92 or less, 0.91 or less, 0.90 or less, 0.89 or less, and 0.88 or less is more preferable.

The cation ratio of the Li ⁺ content to the total content of Li ⁺ and K ⁺ (Li ⁺ /(Li ⁺ +K ⁺ )) can exceed 0.00, thereby maintaining the thermal stability of the glass, further lowering Tg, and improving the meltability of the glass. From the viewpoint of , it is preferably 0.30 or more, more preferably 0.35 or more, and further preferably 0.40 or more, 0.42 or more, 0.44 or more, 0.46 or more, 0.48 or more, 0.50 or more, 0.52 or more, 0.54 or more, and 0.56 or more, in this order. In addition, from the viewpoint of maintaining the thermal stability of the glass, further lowering Tg, and improving the meltability of the glass, the cation ratio (Li ⁺ /(Li ⁺ +K ⁺ )) is preferably 0.99 or less, more preferably 0.98 or less. , the order of 0.97 or less, 0.96 or less, 0.95 or less, 0.94 or less, 0.93 or less, 0.92 or less, 0.91 or less, and 0.90 or less is even more preferable.

The cation ratio of the Li ⁺ content to the total content of Na ⁺ and K ⁺ (Li ⁺ /(Na ⁺ +K ⁺ )) can exceed 0.00, thereby maintaining the thermal stability of the glass, further lowering Tg, and improving the meltability of the glass. From the viewpoint of , it is preferably 0.10 or more, more preferably 0.20 or more, and further preferably 0.25 or more, 0.30 or more, 0.35 or more, 0.40 or more, 0.41 or more, 0.42 or more, 0.43 or more, 0.44 or more, and 0.45 or more, in this order. In addition, from the viewpoint of maintaining the thermal stability of the glass, further lowering Tg, and improving the meltability of the glass, the cation ratio (Li ⁺ /(Na ⁺ +K ⁺ )) is preferably 5.50 or less, more preferably 4.90 or less. , in the order of 4.80 or less, 4.70 or less, 4.60 or less, 4.50 or less, and 4.40 or less, it is further better.

From the viewpoint of maintaining the thermal stability of the glass, further lowering the Tg, and improving the meltability of the glass, the cation ratio of the Na ⁺ content to the total content of Na ⁺ and Li ⁺ (Na ⁺ /(Na ⁺ +Li ⁺ )) Preferably it is 0.85 or less, more preferably 0.80 or less, and further preferably 0.75 or less, 0.74 or less, 0.73 or less, 0.72 or less, 0.71 or less, 0.70 or less, 0.69 or less, 0.68 or less, 0.67 or less, 0.66 or less, and 0.65 or less in this order. In addition, the cation ratio (Na ⁺ /(Na ⁺ +Li ⁺ )) may exceed 0.00, but from the viewpoint of maintaining the thermal stability of the glass, further lowering Tg, and improving the meltability of the glass, it is preferably 0.03 or more, and more preferably It is 0.04 or more, and it is more preferable in the order of 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, and 0.10 or more.

From the viewpoint of maintaining the thermal stability of the glass, further lowering the Tg, and improving the meltability of the glass, the cation ratio of the Na ⁺ content to the total content of Na ⁺ and K ⁺ (Na ⁺ /(Na ⁺ +K ⁺ )) Preferably it is 0.95 or less, more preferably 0.92 or less, and further preferably 0.89 or less, 0.86 or less, 0.85 or less, 0.84 or less, 0.83 or less, 0.82 or less, 0.81 or less, 0.80 or less, 0.79 or less, 0.78 or less, and 0.77 or less in this order. In addition, the cation ratio (Na ⁺ /(Na ⁺ +K ⁺ )) may exceed 0.00, but from the viewpoint of maintaining the thermal stability of the glass, further lowering Tg, and improving the meltability of the glass, it is preferably 0.10 or more, and more preferably 0.15 or more, more preferably 0.20 or more, 0.22 or more, 0.24 or more, 0.26 or more, 0.27 or more, 0.28 or more, 0.29 or more, 0.30 or more, 0.31 or more, and 0.32 or more, in this order.

From the viewpoint of maintaining the thermal stability of the glass, further lowering the Tg, and improving the meltability of the glass, the cation ratio of the Na ⁺ content to the total content of Li ⁺ and K ⁺ (Na ⁺ /(Li ⁺ +K ⁺ )) It is preferably 1.00 or less, more preferably 0.98 or less, and further preferably 0.96 or less, 0.94 or less, 0.92 or less, 0.90 or less, 0.88 or less, 0.86 or less, and 0.84 or less in this order. In addition, the cation ratio (Na ⁺ /(Li ⁺ +K ⁺ )) may exceed 0.00, but from the viewpoint of maintaining the thermal stability of the glass, further lowering Tg, and improving the meltability of the glass, it is preferably 0.03 or more, and more preferably It is 0.05 or more, and it is more preferable in the order of 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, 0.10 or more, and 0.11 or more.

The cation ratio of the K ⁺ content to the total content of K ⁺ and Li ⁺ (K ⁺ /(K ⁺ +Li ⁺ )) can exceed 0.00, thereby maintaining the thermal stability of the glass, further lowering Tg, and improving the meltability of the glass. From the viewpoint of , it is preferably 0.01 or more, more preferably 0.03 or more, and further preferably 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, and 0.09 or more in this order. In addition, from the viewpoint of maintaining the thermal stability of the glass, further lowering Tg, and improving the meltability of the glass, the cation ratio (K ⁺ /(K ⁺ +Li ⁺ )) is preferably 0.70 or less, more preferably 0.65 or less. 0.60 or less, 0.59 or less, 0.58 or less, 0.57 or less, 0.56 or less, 0.55 or less, 0.54 or less, 0.53 or less, 0.52 or less, 0.51 or less, 0.50 or less, 0.49 or less, 0.48 or less, 0.47 or less, 0.46 or less, 0.45 or less, 0.44 The order of below and below 0.43 is even better.

The cation ratio of the K ⁺ content to the total content of K ⁺ and Na ⁺ (K ⁺ /(K ⁺ +Na ⁺ )) can exceed 0.00, thereby maintaining the thermal stability of the glass, further lowering Tg, and improving the meltability of the glass. From the viewpoint of , it is preferably 0.10 or more, more preferably 0.12 or more, and further preferably 0.14 or more, 0.15 or more, 0.16 or more, 0.17 or more, 0.18 or more, 0.19 or more, and 0.20 or more, in this order. In addition, from the viewpoint of maintaining the thermal stability of the glass, further lowering Tg, and improving the meltability of the glass, the cation ratio (K ⁺ /(K ⁺ +Na ⁺ )) is preferably 0.80 or less, more preferably 0.77 or less. The order of 0.75 or less, 0.74 or less, 0.73 or less, 0.72 or less, 0.71 or less, 0.70 or less, 0.69 or less, and 0.68 or less is more preferable.

The cation ratio of the K ⁺ content to the total content of Li ⁺ and Na ⁺ (K ⁺ /(Li ⁺ +Na ⁺ )) can exceed 0.00, thereby maintaining the thermal stability of the glass, further lowering Tg, and improving the meltability of the glass. From the viewpoint of , it is preferably 0.01 or more, more preferably 0.03 or more, and more preferably 0.05 or more, 0.06 or more, 0.07 or more, and 0.08 or more, in this order. In addition, from the viewpoint of maintaining the thermal stability of the glass, further lowering Tg, and improving the meltability of the glass, the cation ratio (K ⁺ /(Li ⁺ +Na ⁺ )) is preferably 1.10 or less, more preferably 1.00 or less. The order of 0.90 or less, 0.80 or less, 0.70 or less, 0.60 or less, 0.59 or less, 0.58 or less, 0.57 or less, 0.56 or less, 0.55 or less, 0.54 or less, 0.53 or less, 0.52 or less, 0.51 or less, and 0.50 or less is more preferable.

From the viewpoint of further lowering Tg and suppressing a decrease in the thermal stability of the glass, the cation ratio of R ²⁺ to the Al ³⁺ content (R ²⁺ /Al ³⁺ ) is preferably 0.74 or less, more preferably 0.73 or less. 0.71 or less, 0.69 or less, 0.67 or less, 0.65 or less, 0.63 or less, 0.61 or less, 0.59 or less, 0.57 or less, 0.55 or less, 0.54 or less, 0.53 or less, 0.52 or less, 0.51 or less, 0.50 or less, 0.49 or less, 0.48 or less, 0.47 The following order is more preferable: 0.46 or less, 0.45 or less, 0.44 or less, 0.43 or less, 0.42 or less, 0.41 or less, 0.40 or less, and 0.39 or less. In addition, the cation ratio (R ²⁺ /Al ³⁺ ) may be 0.00, 0.00 or more, or exceed 0.00. From the viewpoint of further lowering Tg and suppressing a decrease in the thermal stability of the glass, the cation ratio (R ²⁺ /Al ³⁺ ) is preferably 0.00 or more, more preferably 0.005 or more, and further preferably 0.007 or more, and 0.010 or more, in this order .

In one approach, the above-mentioned optical glass may be S ⁶⁺ -free glass.

Pb, As, Cd, Tl, Be and Se are each toxic, so it is better not to contain these elements, that is, not to introduce these elements into the glass as glass components. U, Th and Ra are all radioactive elements. Therefore, it is preferable not to contain these elements, that is, to not introduce these elements into the glass as glass components. V, Cr, Mn, Fe, Co, Ni, Cu, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm and Ce may increase the coloring of the glass or become a source of fluorescence. Therefore, it is preferable not to use it as an element contained in glass for optical elements. Therefore, it is preferable not to contain these elements, that is, to not introduce these elements into the glass as glass components.

Sb and Sn are optionally added elements that function as clarifiers. In terms of the mass fraction (%) of Sb ₂ O ₃ when the mass of the glass is 100, the Sb content of the optical glass may be, for example, 0.40% or less, 0.20% or less, 0.10% or less, 0.05% or less, or 0.02%. Below, below 0.01%. On the other hand, the Sb content may be 0.00% or more or 0.00% based on the mass fraction (%) of Sb ₂ O ₃ when the mass of glass is 100. In terms of the mass fraction (%) of _SnO2 when the mass of the glass is 100, the Sn content of the optical glass may be, for example, 0.40% or less, 0.20% or less, 0.10% or less, 0.05% or less, 0.02% or less, Below 0.01%. On the other hand, the Sn content may be 0.00% or more or 0.00% based on the mass fraction (%) of SnO ₂ when the mass of glass is 100.

The cationic component has been described above. Next, the anionic component will be described.

The above-mentioned optical glass contains at least F ^- as an anionic component.

From the viewpoint of lowering the Tg of the glass and maintaining the low dispersion of the glass, the F ^- content is 19.0% or more, preferably 20.0% or more, preferably 21.0% or more, 22.0% or more, 23.0% or more, 24.0% or more, 25.0% or more. The order of % or more and 26.0% or more is better. In addition, from the viewpoint of suppressing volatilization and further improving the thermal stability of the glass, the F ^- content is preferably 60.0% or less, more preferably 59.0% or less, and 58.0% or less, 57.0% or less, 56.0% or less, or 55.0% or less. , 54.0% or less, 53.0% or less, 52.0% or less, 51.0% or less, 50.0% or less, 49.0% or less, 48.0% or less, 46.0% or less, 45.0% or less, 44.0% or less, in this order, the better.

From the viewpoint of suppressing an increase in Tg, the O ^2- content is 83.0% or less, preferably 82.0% or less, 81.0% or less, 80.0% or less, 79.0% or less, 78.0% or less, 77.0% or less, 76.0% or less, 75.0 The order of % or less, 74.0% or less, 73.0% or less, and 72.0% or less is better. In addition, the O ^2- content may be 0.0%, more than 0.0%, or more than 0.0%. From the viewpoint of high refractive index and further improvement of the thermal stability of the glass, the O ^2- content is preferably 40.0% or more, more preferably 41.0% or more, 42.0% or more, 43.0% or more, 44.0% or more, and 45.0% or more. , 46.0% or more, 47.0% or more, 48.0% or more, 49.0% or more, 50.0% or more, 51.0% or more, 52.0% or more, 53.0% or more, 55.0% or more, in this order, the better.

Examples of anionic components other than the above include Cl ^- , Br ^- and I ^- . The Cl ^- content may be, for example, 0.0%, 0.0% or more, more than 0.0%, 0.10% or more, or 0.20% or more. In addition, for example, it may be 5.0% or less, 4.0% or less, 3.0% or less, 2.0% or less, 1.0% or less, Below 0.50%. The Br ^- content may be, for example, 0.0%, 0.0% or more, more than 0.0%, 0.10% or more, or 0.20% or more. In addition, for example, it may be 5.0% or less, 4.0% or less, 3.0% or less, 2.0% or less, 1.0% or less, Below 0.5%. The I ^- content may be, for example, 0.0%, 0.0% or more, more than 0.0%, 0.10% or more, or 0.20% or more. In addition, for example, it may be 5.0% or less, 4.0% or less, 3.0% or less, 2.0% or less, 1.0% or less, Below 0.5%.

＜Glass physical properties＞ (Abbe number νd) The Abbe number νd, which is an index of dispersion, is expressed as νd=(nd-1)/(nF-nC) using the refractive indices nd, nF, and nC for d-rays, F-rays, and C-rays. From the viewpoint of usefulness as a material for optical elements, the Abbe number νd of the optical glass is preferably 50.00 or more, more preferably 55.00 or more, 60.00 or more, 62.50 or more, 65.00 or more, 67.50 or more, 70.00 or more, 70.50 The order of above, above 71.00, above 71.50, above 72.00, above 72.50, above 73.00 is even better. In addition, the Abbe's number νd of the optical glass may be, for example, 82.00 or less. In projection optical systems such as imaging optical systems and projectors, by combining lenses with different dispersions to form a cemented lens, chromatic aberration can be compensated and the optical system can be miniaturized. Low dispersion is generally easily achieved with plastic lenses. Therefore, optical glass with low dispersion is useful as a material for optical elements constituting imaging optical systems and projection optical systems such as projectors. By having the above-mentioned glass composition, the optical glass can exhibit low dispersion.

(refractive index nd) From the viewpoint of usefulness as a material for optical elements, the refractive index nd of the optical glass may be, for example, 1.420 or more, 1.425 or more, 1.430 or more, 1.435 or more, 1.440 or more, 1.445 or more, 1.446 or more, 1.447 or more, 1.448 or more, 1.449 or more, 1.450 or more, and, for example, 1.510 or less, 1.505 or less, 1.500 or less, 1.4950 or less, 1.490 or less, 1.489 or less, 1.488 or less, 1.487 or less, 1.486 or less, 1.485 or less, 1.484 or less, 1.483 or less, or 1.482 or less. In the present invention and this specification, "refractive index" refers to "refractive index nd", and refractive index nd refers to the refractive index at a wavelength of 587.56 nm.

(Glass transition temperature Tg) By having the above-mentioned glass composition, the optical glass can have a low glass transition temperature. The glass transition temperature Tg of the above-mentioned optical glass is preferably 355°C or lower, more preferably 350°C or lower, 340°C or lower, 330°C or lower, 320°C or lower, 310°C or lower, 300°C or lower, 290°C or lower, 280°C or lower , 270°C or less, and 260°C or less are more preferred. In addition, the glass transition temperature Tg of the optical glass may be, for example, 150°C or higher, 160°C or higher, 170°C or higher, 180°C or higher, 190°C or higher, or 200°C or higher. The glass transition temperature Tg is determined by the method described below.

(proportion) From the viewpoint of reducing the weight of the optical element, the optical glass preferably has a low specific gravity. The specific gravity of the optical glass may be, for example, 3.10 or less, 3.05 or less, 3.00 or less, 2.95 or less, 2.90 or less, or 2.85 or less. In addition, the specific gravity of the optical glass may be, for example, 2.53 or more. The lower the specific gravity, the more preferred. Therefore, the lower limit is not particularly limited.

(Transmittance characteristics) The external transmittance of the above-mentioned optical glass at a wavelength of 500 nm to 1000 nm is more than 80% when converted to a thickness of 10.0 mm. "The external transmittance at a wavelength of 500nm~1000nm when converted to a thickness of 10.0mm is more than 80%" means that the external transmittance when converted to a thickness of 10.0mm is more than 80% in the entire wavelength range of 500nm~1000nm. The external transmittance of the above-mentioned optical glass at a wavelength of 500 nm to 1000 nm can be 80% or more and 100% or less when converted into a thickness of 10.0 mm. Optical glass having this transmittance characteristic is useful as a material for optical elements. For example, by making glass that does not contain Cu ²⁺ as a cationic component, the above-mentioned transmittance characteristics can be achieved.

The transmittance characteristics of the above-mentioned glass are determined by the following method. The glass sample is processed into parallel and optically polished planes, and the external transmittance at a wavelength of 500 to 1000 nm is measured. The external transmittance also includes the reflection loss of light from the sample surface. In addition, when the glass of the measurement object is not glass with the converted thickness, the thickness of the glass is d, the transmittance at each wavelength λ is converted by the following equation A, and the transmission can be obtained by conversion rate characteristics.

Formula A: T(λ)＝(1-R(λ)) ² ×exp(log _e ((T ₀ (λ)/100)/(1-R(λ)) ² )×d/d ₀ )× 100

In formula A, T (λ): converted transmittance (%) at wavelength λ, T ₀ (λ): measured transmittance (%) at wavelength λ, d: converted thickness (mm), d ₀ : Thickness of glass (mm), R(λ)=((n(λ)-1)/(n(λ)+1)) ² represents the reflectivity at wavelength λ, n(λ): refractive index at wavelength λ . For the refractive index n(λ) at wavelength λ, the refraction at each wavelength was measured in accordance with the Japanese Industrial Standard (JIS standard) JIS B 7071-1 "Refractive index measurement method of optical glass - Part 1: Minimum deflection angle method" Rate.

＜How to manufacture optical glass＞ The above-mentioned optical glass can be obtained as follows: weighing and blending phosphates, fluorides, oxides, carbonates, sulfates, nitrates, hydroxides, etc. as raw materials to obtain the target glass composition, and thoroughly mixing The mixed masterbatch is prepared, heated, melted, degassed, and stirred in a melting container to produce uniform, bubble-free molten glass, which is then molded to obtain optical glass. Specifically, it can be produced using a known melting method.

[Glass raw materials for press molding, optical element blanks, and their manufacturing methods] Another embodiment of the invention relates to: Glass raw materials for press molding containing the above-mentioned optical glass; and An optical element blank containing the above-mentioned optical glass.

According to another embodiment of the present invention, there is also provided: A method of manufacturing a glass raw material for press molding including a step of molding the above optical glass into a glass raw material for press molding; A method for manufacturing an optical element blank including a step of press-molding the above-mentioned glass raw material for press-molding optical glass using a press-molding mold to produce an optical element blank; and A method for manufacturing an optical element blank including a step of molding the optical glass described above into an optical element blank.

The optical element blank is a material that is similar to the shape of the target optical element, and has a polishing material (a surface layer that will be removed by polishing) added to the shape of the optical element, and a grinding material (a surface layer that will be removed by polishing) if necessary. Surface layer removed by grinding) optical element base material. The optical element is finished by grinding and polishing the surface of the optical element blank. In one embodiment, the optical element blank can be produced by press-molding a molten glass obtained by melting an appropriate amount of the above-mentioned glass (called a direct press method). In another embodiment, an optical element blank can also be produced by solidifying a molten glass obtained by melting an appropriate amount of the above-mentioned glass.

In another embodiment, an optical element blank can be produced by producing a glass material for press molding and press-molding the produced glass material for press molding.

Pressure molding of the glass raw material for press molding can be performed by a known method of pressurizing the heated and softened glass raw material for press molding using a press molding die. Both heating and pressure molding can be performed in the atmosphere. By annealing after pressure molding to reduce the strain inside the glass, a uniform optical element blank can be obtained.

As for the glass raw material for press molding, in addition to the raw material called glass gob for press molding that is directly supplied to the press molding for producing the optical element blank in its original state, there are also Including raw materials that are supplied to pressure molding after mechanical processing such as cutting, grinding, and polishing, and passing through glass gobs for pressure molding. The cutting method includes the following method: forming a groove on the part to be cut on the surface of the glass plate by a method called scribing, applying local pressure to the groove part from the back side of the side on which the groove is formed, and placing the groove on the surface of the glass plate. The method of partially cutting the glass plate; the method of cutting the glass plate with a cutting knife, etc. In addition, examples of grinding and polishing methods include barrel polishing and the like.

The glass raw material for pressure molding can be produced by, for example, casting molten glass into a mold and shaping it into a glass plate, and cutting the glass plate into a plurality of glass sheets. Alternatively, an appropriate amount of molten glass may be molded to produce glass gobs for pressure molding. The optical element blank can also be produced by reheating and softening the glass gob for pressure molding and performing pressure molding. The method of reheating, softening, and press-molding glass to produce an optical element blank is called a reheat press method compared to the direct press method.

[Optical elements and manufacturing methods thereof] Another embodiment of the invention relates to: Optical elements containing the above-mentioned optical glass. The above-mentioned optical element is produced using the above-mentioned optical glass. In the optical element described above, one or more coating layers, such as a multilayer film such as an antireflection film, may be formed on the glass surface.

In addition, according to an embodiment of the present invention, it can also be provided: An optical element manufacturing method including a step of producing an optical element by grinding and/or polishing the above-mentioned optical element blank.

In the above-mentioned manufacturing method of optical elements, mechanical processing such as grinding and polishing can be performed by known methods. By fully cleaning and drying the surface of the optical element after processing, optical elements with high internal and surface quality can be obtained. . In this way, an optical element formed of the above-mentioned optical glass can be obtained. Examples of optical elements include various lenses such as spherical lenses, aspherical lenses, and microlenses, prisms, and the like.

In addition, the optical element formed of the above-mentioned optical glass is also suitably used as a lens constituting a joint optical element. Examples of the bonded optical element include an element in which lenses are bonded to each other (cemented lens), an element in which a lens and a prism are bonded, and the like. For example, a bonded optical element can be produced by precisely processing the bonding surface of two optical elements to be bonded so that their shapes become inverted shapes (for example, spherical polishing), and applying a coating for bonding the lens. The ultraviolet curing adhesive is used to bond them. After they are bonded, ultraviolet rays are irradiated through the lens to solidify the adhesive, thereby making the joint optical components. A plurality of elements to be joined can be made using various types of glass with different Abbe numbers vd, etc., and then joined together to produce an element suitable for compensating chromatic aberration. [Example]

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the embodiments shown in the examples.

[Example 1] ＜Sample No.1~63＞ In order to achieve the glass composition shown in the table below, the corresponding phosphate, fluoride, nitrate, sulfate, carbonate, hydroxide, oxide, boric acid, etc. are used as raw materials for introducing each component. Measure the raw materials and mix them thoroughly to prepare the prepared raw materials. This prepared raw material was put into a platinum crucible, heated in a furnace set to 700 to 1100°C, and melted for 90 minutes. After the molten glass is stirred and homogenized, the molten glass is poured into a preheated mold. After natural cooling to near the glass transition temperature, it is immediately placed in an annealing furnace and maintained at a temperature around the glass transition temperature for about 30 minutes. By slowly cooling at a slow cooling rate of -30° C./hour for 4 hours, and then naturally cooling to room temperature in the furnace, optical glasses of sample Nos. 1 to 63 shown in the following tables were obtained.

[Comparative Example A, Comparative Example B] In order to achieve the glass composition shown in the table below, the corresponding phosphate, fluoride, nitrate, sulfate, carbonate, hydroxide, oxide, boric acid, etc. are used as raw materials for introducing each component. Measure the raw materials and mix them thoroughly to prepare the prepared raw materials. This prepared raw material was put into a platinum crucible, heated in a furnace set to 700 to 1100°C, and melted for 90 minutes. After the molten glass is stirred and homogenized, the molten glass is poured into a preheated mold. After natural cooling to near the glass transition temperature, it is immediately placed in an annealing furnace and maintained at a temperature around the glass transition temperature for about 30 minutes. The optical glass of Comparative Example A and Comparative Example B shown in the following table was obtained by slowly cooling for 4 hours at a slow cooling rate of -30° C./hour, and then naturally cooling to room temperature in the furnace. Comparative Example A corresponds to Example 33 of WO2003/037813 (Patent Document 1), and Comparative Example B corresponds to Example 35 of WO2003/037813 (Patent Document 1).

＜Physical property evaluation＞ Each physical property of each optical glass shown in the following table was measured by the method shown below.

(1) Refractive index nd, Abbe’s number νd For each optical glass, the refractive index nd and Abbe's number νd were measured by the refractive index measurement method standardized by the Japan Optical Glass Industry Association. Regarding Comparative Example A, since the glass was devitrified, the refractive index nd and Abbe's number νd could not be measured.

(2) Glass transition temperature Tg The glass was thoroughly crushed with a mortar and used as a sample. A platinum cell was used as a sample container. The temperature rise rate was set to 10°C/min using a differential scanning calorimetry analysis device (DSC3300SA) manufactured by NETZSCH JAPAN. The glass transition temperature Tg was measured.

(3) Proportion The specific gravity was determined by Archimedes' method.

(4) Transmittance characteristics A test piece was cut out from the obtained glass, and both sides were mirror-polished to form optically polished planes parallel to each other. After the thickness reached 10.0 mm, a spectrophotometer was used to measure the external transmittance at a wavelength of 500 to 1000 nm. Determination was carried out. In any of Sample Nos. 1 to 63, Comparative Examples A and Comparative Examples B, it was confirmed that the external transmittance at a wavelength of 500 nm to 1000 nm was 80% or more and 100% or less when the thickness was 10.0 mm.

<Evaluation of thermal stability> For sample Nos. 1 to 63, Comparative Example A and Comparative Example B, corresponding phosphates, fluorides, nitrates, and Sulfates, carbonates, hydroxides, oxides, boric acid, etc. are used as raw materials for introducing each component. The raw materials are weighed and thoroughly mixed to prepare the prepared raw materials. This prepared raw material was put into a platinum crucible, heated in a furnace set to 700 to 1100°C, and melted for 90 minutes. After the molten glass was stirred and homogenized, the molten glass was cast into a mold, molded, and slowly cooled to obtain a massive glass sample. The obtained glass sample was observed with an optical microscope for crystals in the glass. Set the magnification of the optical microscope to 40 to 100 times. When no crystals are confirmed in the glass block, it is judged as A. When more than 1 and 15 or less crystals are confirmed per 1 cm ³ on average, it is judged as B. When 16 or more and 40 crystals are confirmed on average per 1 cm ³ , it is judged as B. When there are less than 40 crystals per 1 cm 3 , it is judged as C, and when more than 40 crystals are confirmed per 1 cm ³ , it is judged as D. Regarding A, B, and C, the thermal stability increases in the order of C→B→A, and A has the highest thermal stability. If it is A, B, or C, the internal quality, which is the number of crystals contained in the glass during production, is within the allowable range. Glass with a judgment result of D lacks thermal stability and is of poor internal quality in terms of manufacturing. As shown in the following table, it was confirmed that the glass of sample Nos. 1 to 63 has excellent thermal stability (judgment result A, B, or C).

(Example 2) A glass block (glass gob) for press molding was produced using various glasses obtained in Example 1. The glass gob was heated and softened in the air, and then press-molded using a pressure molding die to produce a lens blank (optical element blank). The produced lens blank was taken out from the pressure molding mold, annealed, and machined including polishing to produce spherical lenses made of various glasses produced in Example 1.

(Example 3) A desired amount of the molten glass produced in Example 1 was press-molded using a press-molding die to produce a lens blank (optical element blank). The produced lens blank was taken out from the pressure molding mold, annealed, and mechanically processed including polishing to produce spherical lenses made of various glasses produced in Example 1.

(Example 4) The glass block (optical element blank) produced by solidifying the molten glass produced in Example 1 was annealed and machined including polishing to produce spherical lenses made of various glasses produced in Example 1.

Finally, each of the above-described embodiments is summarized.

[1] An optical glass in which the Li ⁺ content exceeds 0.0 cation % and is 48.0 cation % or less, the Na ⁺ content exceeds 0.0 cation % and is 35.0 cation % or less, and the K ⁺ content exceeds 0.0 cation % and 30.0 cation % or less, the total content of Al ³⁺ and P ⁵⁺ (Al ³⁺ +P ⁵⁺ ) is 38.0 cation % or more and 70.0 cation % or less, where Li ⁺ , Na ⁺ , K The total content of ⁺ and Cs ⁺ is set to R ⁺ , and the total content of Be ²⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ is set to R ²⁺ , R ⁺ is relative to Al ³⁺ and P The cation ratio of the total content of ⁵⁺ (R ⁺ /(Al ³⁺ +P ⁵⁺ )) is 0.93 or more, and the Li ⁺ content relative to the total cation ratio of R ⁺ and R ²⁺ (Li ⁺ /(R ⁺ + R ²⁺ )) is 0.29 or more, and the cation ratio of the total content of Li ⁺ and K ⁺ to the total content of Al ³⁺ and P ⁵⁺ ((Li ⁺ +K ⁺ )/(Al ³⁺ +P ⁵⁺ ) ) is 0.56 or more, the cation ratio of R ²⁺ to the total of Al ³⁺ content and R ²⁺ (R ²⁺ /(Al ³⁺ +R ²⁺ )) is 0.37 or less, and the glass composition expressed as anion % Among them, the O ^{2 -} content is 83.0 anion % or less, the F ^- content is 19.0 anion % or more, and the external transmittance of the optical glass at a wavelength of 500 nm to 1000 nm is more than 80% when converted to a thickness of 10.0 mm. [2] The optical glass according to [1], wherein the cation ratio of the total content of Li ⁺ and Na ⁺ to the total content of Li ⁺ and K ⁺ ((Li ⁺ +Na ⁺ )/(Li ⁺ +K ⁺ )) is 0.50 or more and 1.59 or less. [3] The optical glass according to [1] or [2], wherein the cation ratio of the total content of Na ⁺ and K ⁺ to the total content of Li ⁺ and K ⁺ ((Na ⁺ +K ⁺ )/( Li ⁺ +K ⁺ )) is 0.05 or more and 2.00 or less. [4] The optical glass according to any one of [1] to [3], wherein the cation ratio of the Li ⁺ content to the total content of Li ⁺ and Na ⁺ (Li ⁺ /(Li ⁺ +Na ⁺ ) ) is 0.05 or more and 1.00 or less. [5] The optical glass according to any one of [1] to [4], wherein the cation ratio of the Li ⁺ content to the total content of Li ⁺ and K ⁺ (Li ⁺ /(Li ⁺ +K ⁺ ) ) is 0.30 or more and 0.99 or less. [6] The optical glass according to any one of [1] to [5], wherein the cation ratio of the Li ⁺ content to the total content of Na ⁺ and K ⁺ (Li ⁺ /(Na ⁺ +K ⁺ ) ) is 0.10 or more and 5.00 or less. [7] The optical glass according to any one of [1] to [6], wherein the cation ratio of the Na ⁺ content to the total content of Na ⁺ and Li ⁺ (Na ⁺ /(Na ⁺ +Li ⁺ ) ) is less than 0.85. [8] The optical glass according to any one of [1] to [7], wherein the cation ratio of the Na ⁺ content to the total content of Na ⁺ and K ⁺ (Na ⁺ /(Na ⁺ +K ⁺ ) ) is less than 0.95. [9] The optical glass according to any one of [1] to [8], wherein the cation ratio of the Na ⁺ content to the total content of Li ⁺ and K ⁺ (Na ⁺ /(Li ⁺ +K ⁺ ) ) is less than 1.00. [10] The optical glass according to any one of [1] to [9], wherein the cation ratio of the K ⁺ content to the total content of K ⁺ and Li ⁺ (K ⁺ /(K ⁺ +Li ⁺ ) ) is 0.01 or more and 0.70 or less. [11] The optical glass according to any one of [1] to [10], wherein the cation ratio of the K ⁺ content to the total content of K ⁺ and Na ⁺ (K ⁺ /(K ⁺ +Na ⁺ ) ) is 0.10 or more and 0.80 or less. [12] The optical glass according to any one of [1] to [11], wherein the cation ratio of the K ⁺ content to the total content of Li ⁺ and Na ⁺ (K ⁺ /(Li ⁺ +Na ⁺ ) ) is 0.01 or more and 1.00 or less. [13] The optical glass according to any one of [1] to [12], wherein the cation ratio of R ²⁺ to the Al ³⁺ content (R ²⁺ /Al ³⁺ ) is 0.74 or less. [14] The optical glass according to any one of [1] to [13] has a glass transition temperature Tg of 150°C or more and 355°C or less. [15] The optical glass according to [1], wherein the cation ratio of the total content of Li ⁺ and Na ⁺ to the total content of Li ⁺ and K ⁺ ((Li ⁺ +Na ⁺ )/(Li ⁺ +K ⁺ )) is 0.50 or more and 1.59 or less, and the cation ratio ((Na ⁺ +K ⁺ )/(Li ⁺ +K ⁺ )) of the total content of Na ⁺ and K ⁺ to the total content of Li ⁺ and K ⁺ is 0.05 or more and 2.00 or less, the cation ratio (Li ⁺ /(Li ⁺ +Na ⁺ )) of the Li ⁺ content relative to the total content of Li ⁺ and Na ⁺ is 0.05 or more and 1.00 or less, the Li ⁺ content relative to Li ⁺ and K ⁺ The cation ratio (Li ⁺ /(Li ⁺ +K ⁺ )) of the total content of is ^0.30 or more and 0.99 or less, and the cation ratio ( ^{Li + /} (Na ^{+ +} K ⁺ )) is 0.10 or more and 5.00 or less, the cation ratio of the Na ⁺ content to the total content of Na ⁺ and Li ⁺ (Na ⁺ /(Na ⁺ +Li ⁺ )) is 0.85 or less, the Na ⁺ content is 0.85 or less relative to the total content of Na ^{+ and Li +} The cation ratio of the total content of K ⁺ (Na ⁺ /(Na ⁺ +K ⁺ )) is 0.95 or less, and the cation ratio of the Na ⁺ content to the total content of Li ⁺ and K ⁺ (Na ⁺ /(Li ⁺ +K ⁺ )) is 1.00 or less, the cation ratio (K ⁺ /(K ⁺ +Li ⁺ )) of the K ⁺ content relative to the total content of K ⁺ and Li ⁺ is 0.01 or more and 0.70 or less, the K ⁺ content relative to the K ⁺ and Na The cation ratio of the total content of ⁺ (K ⁺ /(K ⁺ +Na ⁺ )) is 0.10 or more and 0.80 or less, and the cation ratio of the K ⁺ content to the total content of Li ⁺ and Na ⁺ (K ⁺ /(Li ⁺ + Na ⁺ )) is 0.01 or more and 1.00 or less, the cation ratio of R ²⁺ to Al ³⁺ content (R ²⁺ /Al ³⁺ ) is 0.74 or less, and the glass transition temperature Tg of the optical glass is 150°C. Above and below 355℃. [16] An optical element including the optical glass according to any one of [1] to [15].

It should be understood that the embodiments disclosed this time are all exemplary and not limiting. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope equivalent to the claims. For example, by adjusting the composition described in the specification with respect to the glass composition exemplified above, optical glass according to one embodiment of the present invention can be obtained. It goes without saying that two or more of the matters exemplified in the specification or described as preferred ranges can be arbitrarily combined.

without

without

Claims (16)

An optical glass in which the Li ⁺ content exceeds 0.0 cation % and is 48.0 cation % or less, the Na ⁺ content exceeds 0.0 cation % and is 35.0 cation % or less, and the K ⁺ content exceeds 0.0 cation % in the glass composition expressed as cation % And is 30.0 cation % or less, the total content of Al ³⁺ and P ⁵⁺ (Al ³⁺ +P ⁵⁺ ) is 38.0 cation % or more and 70.0 cation % or less, where Li ⁺ , Na ⁺ , K ⁺ and Cs Let the total content of ⁺ be R ⁺ , let the total content of Be ²⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ be R ²⁺ , and R ⁺ with respect to Al ³⁺ and P ⁵⁺ The cation ratio of the total content (R ⁺ /(Al ³⁺ +P ⁵⁺ )) is 0.93 or more, and the Li ⁺ content relative to the total cation ratio of R ⁺ and R ²⁺ (Li ⁺ /(R ⁺ +R ²⁺ )) is 0.29 or more, and the cation ratio ((Li ⁺ +K ⁺ )/(Al ³⁺ +P ⁵⁺ )) of the total content of Li ⁺ and K ⁺ to the total content of Al ³⁺ and P ⁵⁺ is 0.56 As above, the cation ratio of R ²⁺ to the total of Al ³⁺ content and R ²⁺ (R ²⁺ /(Al ³⁺ +R ²⁺ )) is 0.37 or less. In the glass composition expressed as anion %, O The ^2- content is 83.0 anion % or less, the F ^- content is 19.0 anion % or more, and the external transmittance of the optical glass at a wavelength of 500 nm to 1000 nm is more than 80% when converted to a thickness of 10.0 mm. The optical glass according to claim 1, wherein the cation ratio of the total content of Li ⁺ and Na ⁺ to the total content of Li ⁺ and K ⁺ ((Li ⁺ +Na ⁺ )/(Li ⁺ +K ⁺ )) It is above 0.50 and below 1.59. The optical glass according to claim 1, wherein the cation ratio of the total content of Na ⁺ and K ⁺ to the total content of Li ⁺ and K ⁺ ((Na ⁺ +K ⁺ )/(Li ⁺ +K ⁺ )) It is 0.05 or more and 2.00 or less. The optical glass according to claim 1, wherein the cation ratio of the Li ⁺ content to the total content of Li ⁺ and Na ⁺ (Li ⁺ /(Li ⁺ +Na ⁺ )) is 0.05 or more and 1.00 or less. The optical glass according to claim 1, wherein the cation ratio of the Li ⁺ content to the total content of Li ⁺ and K ⁺ (Li ⁺ /(Li ⁺ +K ⁺ )) is 0.30 or more and 0.99 or less. The optical glass according to claim 1, wherein the cation ratio of the Li ⁺ content to the total content of Na ⁺ and K ⁺ (Li ⁺ /(Na ⁺ +K ⁺ )) is 0.10 or more and 5.00 or less. The optical glass according to claim 1, wherein the cation ratio of the Na ⁺ content to the total content of Na ⁺ and Li ⁺ (Na ⁺ /(Na ⁺ +Li ⁺ )) is 0.85 or less. The optical glass according to claim 1, wherein the cation ratio of the Na ⁺ content to the total content of Na ⁺ and K ⁺ (Na ⁺ /(Na ⁺ +K ⁺ )) is 0.95 or less. The optical glass according to claim 1, wherein the cation ratio of the Na ⁺ content to the total content of Li ⁺ and K ⁺ (Na ⁺ /(Li ⁺ +K ⁺ )) is 1.00 or less. The optical glass according to claim 1, wherein the cation ratio of the K ⁺ content to the total content of K ⁺ and Li ⁺ (K ⁺ /(K ⁺ +Li ⁺ )) is 0.01 or more and 0.70 or less. The optical glass according to claim 1, wherein the cation ratio of the K ⁺ content to the total content of K ⁺ and Na ⁺ (K ⁺ /(K ⁺ +Na ⁺ )) is 0.10 or more and 0.80 or less. The optical glass according to claim 1, wherein the cation ratio of the K ⁺ content to the total content of Li ⁺ and Na ⁺ (K ⁺ /(Li ⁺ +Na ⁺ )) is 0.01 or more and 1.00 or less. The optical glass according to claim 1, wherein the cation ratio of R ²⁺ to the Al ³⁺ content (R ²⁺ /Al ³⁺ ) is 0.74 or less. The optical glass according to claim 1, wherein the glass transition temperature Tg is 150°C or more and 355°C or less. The optical glass according to claim 1, wherein the cation ratio of the total content of Li ⁺ and Na ⁺ to the total content of Li ⁺ and K ⁺ ((Li ⁺ +Na ⁺ )/(Li ⁺ +K ⁺ )) is 0.50 or more and 1.59 or less, and the cation ratio ((Na ⁺ +K ^{+ )} /(Li ⁺ +K ⁺ )) of the total content of Na ⁺ and K ⁺ to the total content of Li ⁺ and K + is 0.05 or more and 2.00 Hereinafter, the cation ratio ( ^{Li + /} (Li ⁺ +Na ⁺ )) of the Li ⁺ content relative to the total content of Li + and Na ⁺ is 0.05 or more and 1.00 or less, and the Li ⁺ content relative to the total content of Li ⁺ and K ⁺ The cation ratio (Li ⁺ /(Li ⁺ +K ⁺ )) is 0.30 or more and 0.99 or less, and the cation ratio (Li ⁺ /(Na ⁺ +K ⁺ )) of the Li ⁺ content relative to the total content of Na ⁺ and K ⁺ is 0.10 or more and 5.00 or less, the cation ratio of the Na ⁺ content to the total content of Na ⁺ and Li ⁺ (Na ⁺ /(Na ⁺ +Li ⁺ )) is 0.85 or less, the Na ⁺ content relative to the Na ⁺ and K ⁺ The cation ratio of the total content (Na ⁺ /(Na ⁺ +K ⁺ )) is 0.95 or less, and the cation ratio of the Na ⁺ content relative to the total content of Li ⁺ and K ⁺ (Na ⁺ /(Li ⁺ +K ⁺ )) is 1.00 or less, the cation ratio (K ⁺ /(K ⁺ +Li ⁺ )) of the K ⁺ content relative to the total content of K ⁺ and Li ⁺ is 0.01 or more and 0.70 or less, the K ⁺ content relative to the total content of K ⁺ and Na ⁺ The cation ratio of the content (K ⁺ /(K ⁺ +Na ⁺ )) is 0.10 or more and 0.80 or less, and the cation ratio of the K ⁺ content relative to the total content of Li ⁺ and Na ⁺ (K ⁺ /(Li ⁺ +Na ⁺ ) ) is 0.01 or more and 1.00 or less, the cation ratio of R ²⁺ to Al ³⁺ content (R ²⁺ /Al ³⁺ ) is 0.74 or less, and the glass transition temperature Tg of the optical glass is 150°C or more and 355 below ℃. An optical element comprising the optical glass as described in any one of claims 1 to 15.