TWI883455B - Optical glass and optical components - Google Patents

Abstract

The present invention provides optical glass with low glass transition temperature and excellent thermal stability. In the glass composition expressed as cation %, the Li ⁺ content of the optical glass is greater than 0.0 cation % and less than 48.0%, the Na ⁺ content is greater than 0.0 cation % and less than 35.0%, the K ⁺ content is greater than 0.0 cation % and less than 30.0%, the total content (Al ³⁺ +P ⁵⁺ ) is 38.0~70.0%, the total content of Li ⁺ , Na ⁺ , 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⁺ , the cation ratio (R ⁺ /(Al ³⁺ +P ⁵⁺ )) is greater than 0.93, the (Li ⁺ /(R ^{+ +} R 2+ )) is greater than 0.29, and the ((Li + /(R + +R ²⁺ )) is greater than 0.5 ⁺ +K ⁺ )/(Al ³⁺ +P ⁵⁺ )) is greater than 0.56, (R ²⁺ /(Al ³⁺ +R ²⁺ )) is less than 0.37, in the glass composition expressed in anion %, the O ^2- content is less than 83.0%, the F ^- content is greater than 19.0%, and its external transmittance at a wavelength of 500nm~1000nm converted to a thickness of 10.0mm is greater than 80%.

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 Document] [Patent Document]

Patent document 1: WO2003/037813

[Problem to be solved by the invention]

Glass with a low glass transition temperature can be molded at a low temperature. From the perspective of less degradation of the molding mold due to heating and the ability to use a molding mold with low heat resistance and low price, it is preferable to be able to mold at a low temperature. However, the inventors have studied optical glass with a low glass transition temperature and found that further improvement in thermal stability is expected.

One aspect of the present invention is to provide optical glass having a low glass transition temperature and excellent thermal stability. [Means for solving the problem]

One embodiment of the present invention relates to an optical glass, in which, in a glass composition expressed as cation %, a Li ⁺ content exceeds 0.0 cation % and is less than 48.0 cation %; a Na ⁺ content exceeds 0.0 cation % and is less than 35.0 cation %; a K ⁺ content exceeds 0.0 cation % and is less than 30.0 cation %; a total content of Al3 ⁺ and P5 ⁺ (Al3 ⁺ +P5 ⁺ ) is greater than or equal to 38.0 cation % and less than 70.0 cation %; wherein the total content of Li ⁺ , Na ⁺ , K ⁺ and Cs ⁺ is set to R ⁺ , and the total content of Be2 ⁺ , Mg2 ⁺ , Ca2 ⁺ , Sr2 ⁺ and Ba2 ⁺ is set to R ²⁺ , 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, the cation ratio of Li ⁺ content to the total content of R ⁺ and R ²⁺ (Li ⁺ /(R ⁺ +R ²⁺ )) is 0.29 or more, 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 content of Al ³⁺ and R ²⁺ (R ²⁺ /(Al ³⁺ +R ²⁺ )) is 0.37 or less, and in the glass composition expressed as anion %, O ^{The 2-} content is less than 83.0 anion %, the F ^- content is more than 19.0 anion %, and the external transmittance of the optical glass at the above wavelength of 500nm~1000nm converted into a thickness of 10.0mm is more than 80%.

The optical glass having the glass composition can have a low glass transition temperature and can exhibit excellent thermal stability. [Effects of the invention]

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

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

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

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

<Glass composition> The glass composition of the above optical glass expressed in cation % is described below. In the present invention and this specification, the total content of Li ⁺ , Na ⁺ , K ⁺ and Cs ⁺ is also referred to as "R ⁺ ", and the total content of Be ²⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ is also referred to 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 its solubility, the Li ⁺ content exceeds 0.0%, preferably at least 2.0%, and more preferably at least 4.0%, at least 6.0%, at least 8.0%, at least 10.0%, at least 11.0%, at least 12.0%, at least 13.0%, at least 14.0%, at least 15.0%, at least 16.0%, and at least 17.0%. In addition, from the perspective 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, and more preferably 46.0 %, 45.0 %, 44.0 %, 43.0 %, 42.0 %, 41.0 % or less, and 40.0 % or less in this order.

From the viewpoint of maintaining the refractive index, maintaining low dispersion, lowering the Tg of the glass, improving the melting property and lowering the specific gravity, the Na ⁺ content exceeds 0.0 cation %, preferably 1.0% or more, more preferably 2.0% or more, 3.0% or more, 4.0% or more, and 5.0% or more in this order. 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, and more preferably 33.0% or less, 32.0% or less, 31.0% or less, 30.0% or less, 29.0% or less, 28.0% or less, 27.0% or less, and 26.0% or less in this order.

From the viewpoint of maintaining the refractive index, maintaining low dispersion, lowering the Tg of the glass, and improving the solubility, the K ⁺ content exceeds 0.0 cation %, preferably 1.0% or more, more preferably 2.0% or more, 3.0% or more, and 4.0% or more in this order. 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, and more preferably 28.0% or less, 27.0% or less, 26.0% or less, 25.0% or less, 24.0% or less, 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 in this order.

The Cs ⁺ content may be 0.0%, or may be greater than 0.0%, or may be greater than 0.0%. From the perspective of further lowering the Tg of the glass and improving the solubility of the glass, the Cs ⁺ content may be greater than 0.0%, preferably greater than 0.1%, and more preferably in the order of greater than 0.2%, greater than 0.3%, greater than 0.4%, greater than 0.5%, and greater than 0.6%. In addition, from the perspective of further improving the thermal stability of the glass and inhibiting the reduction of chemical durability, the Cs ⁺ content is preferably less than 10.0%, and more preferably in the order of less than 8.0%, less than 6.0%, less than 4.0%, less than 2.0%, less than 1.5%, and less than 1.0%.

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

From the perspective 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 more preferably 38.2 %, 38.3 %, 38.4 %, 38.5 %, 38.6 %, 38.7 %, 38.8 %, 38.9 %, and 39.0 % or more, in this order. In addition, from the perspective of suppressing the increase in Tg, the total content of Al ³⁺ and P ⁵⁺ (Al ³⁺ +P ⁵⁺ ) is less than 70.0 cation %, preferably less than 65.0%, and more preferably less than 60.0%, less than 59.0%, less than 58.0%, less than 57.0%, less than 56.0%, less than 55.0%, less than 54.0%, less than 53.0%, less than 52.0%, less than 51.0%, and less than 50.0% in this order.

From the viewpoint of increasing the refractive index while 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 greater than 0.0%, more preferably greater than 1.0%, and further preferably greater than 2.0%, greater than 3.0%, greater than 4.0%, greater than 5.0%, greater than 6.0%, greater than 7.0%, greater than 8.0%, greater than 9.0%, greater than 10.0%, and greater than 11.0%, in this order. In addition, from the viewpoint of further suppressing the increase in Tg, the Al ³⁺ content is preferably 30.0% or less, more preferably 29.0% or less, and further preferably 28.0% or less, 27.0% or less, 26.0% or less, 25.0% or less, 24.0% or less, 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, in this order.

From the viewpoint of maintaining low dispersion and further improving the thermal stability of the glass, the P5 ⁺ content is preferably 5.0% or more, more preferably 7.0% or more, and further preferably 9.0% or more, 11.0% or more, 13.0% or more, 14.0% or more, 15.0% or more, 16.0% or more, 17.0% or more, 18.0% or more, 19.0% or more, 20.0% or more, 21.0% or more, 22.0% or more, and 23.0% or more in this order. In addition, from the viewpoint of maintaining the refractive index, further improving the thermal stability of the glass and inhibiting the reduction of chemical durability, the P5 ⁺ content is preferably 50.0% or less, more preferably 48.0% or less, and is further preferably 46.0% or less, 44.0% 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, in this order.

From the viewpoint of lowering the Tg of the glass and improving the solubility of the glass, the cation ratio of R ⁺ to the total content of Al3 ⁺ and ^P5+ (R ⁺ /( ^Al3 ++P5 ⁺ )) is 0.93 or more, preferably 0.94 or more, and more preferably 0.95 or more and 0.96 or more. 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 further preferably 2.50 or less, 2.25 or less, 2.00 or less, 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, in this order.

From the viewpoint of increasing the refractive index, lowering the Tg of the glass, and improving the solubility of the glass, the cation ratio of the Li ⁺ content to the total of R ⁺ and R ²⁺ (Li ⁺ /(R ⁺ +R ²⁺ )) is 0.29 or more, preferably 0.30 or more, more preferably 0.31 or more, and more preferably 0.32 or more. 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, and more preferably 0.94 or less, 0.93 or less, 0.92 or less, 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.

From the perspective of further lowering the Tg of the glass, improving the solubility 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 greater than 0.56, preferably greater than 0.57, and more preferably greater than 0.58, greater than 0.59, greater than 0.60, greater than 0.61, greater than 0.62, greater than 0.63, greater than 0.64, and greater than 0.65 in this order. 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 further preferably 1.70 or less, 1.60 or less, 1.50 or less, 1.40 or less, 1.30 or less, 1.20 or less, and 1.10 or less, in this order.

From the viewpoint of maintaining the thermal stability of the glass, the cation ratio of R ²⁺ to the sum of the Al ³⁺ content and R ²⁺ (R ²⁺ /(Al ³⁺ +R ²⁺ )) is 0.37 or less, preferably 0.36 or less, and more 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 greater than 0.00 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 further preferably 0.02 or more, and then 0.03 or more.

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 the increase of 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 more preferably 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% or less, 11.0% or less, 10.0% or less, 9.0% or less, 8.0% or less, and 7.0% or less in this order.

The Be ²⁺ content may be 0.0%, 0.0% or more, or more than 0.0%. From the perspective of maintaining the refractive index, maintaining low dispersion, suppressing the rise of 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 more preferably 5.0% or less, 2.5% or less, 1.5% or less, 1.0% or less, and 0.5% or less in this order. The Mg ²⁺ content 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 the increase of 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 more preferably 13.0% or less, 12.0% or less, 11.0% or less, 10.0% or less, 9.0% or less, 8.0% or less, 7.0% or less, and 6.0% or less in this order. The Ca ²⁺ content 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 the increase of 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 more preferably 8.0% or less, 7.0% or less, 6.0% or less in this order. The Sr ²⁺ content may be 0.0%, 0.0% or more, or more than 0.0%. From the perspective of maintaining the refractive index, maintaining low dispersion, suppressing the rise of 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 further preferably 8.0% or less, 7.0% or less, 6.0% or less, 5.0% or less, and 4.0% or less. The Ba ²⁺ content may be 0.0%, 0.0% or more, or more than 0.0%. From the perspective of maintaining the refractive index, maintaining low dispersion, suppressing the increase in Tg and maintaining the thermal stability of the glass, the Ba2 ⁺ content is preferably 10.0% or less, more preferably 9.0% or less, and further preferably 8.0% or less, 7.0% or less, 6.0% or less, 5.0% or less, 4.0% or less, 3.0% or less, and 2.0% or less, in this order.

The Zn ²⁺ content may be 0.0%, 0.0% or more, or more than 0.0%. Zn ²⁺ plays a role in maintaining the refractive index and improving thermal stability, but if it is contained in excess, there is a tendency for dispersion to increase. From the above viewpoints, the Zn ²⁺ content is preferably 20.0% or less, more preferably 19.0% or less, and more preferably 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% or less, 11.0% or less, 10.0% or less, 9.0% or less, 8.0% or less, 7.0% or less, 6.0% or less, and 5.0% or less in this order.

The Zr ⁴⁺ content may be 0.0%, 0.0% or more, or more than 0.0%. Zr ⁴⁺ is a component that increases the refractive index, but if it is contained in excess, there is a tendency for the dispersion to increase and the Tg to rise. From the above viewpoints, the Zr ⁴⁺ content is preferably 10.0% or less, more preferably 9.0% or less, and further preferably 8.0% or less, 7.0% or less, 6.0% or less, 5.0% or less, 4.0% or less, 3.0% or less, and 2.0% or less in this order.

The Nb ⁵⁺ content may be 0.0%, 0.0% or more, or more than 0.0%. Nb ⁵⁺ is a component that increases the refractive index, but if contained in excessive amounts, there is a tendency for dispersion to increase and Tg to rise. From the above viewpoints, the Nb ⁵⁺ content is preferably 10.0% or less, more preferably 9.0% or less, and further preferably 8.0% or less, 7.0% or less, 6.0% or less, 5.0% or less, 4.0% or less, 3.0% or less, and 2.0% or less in this order.

The Ti ⁴⁺ content may be 0.0%, 0.0% or more, or more than 0.0%. Ti ⁴⁺ increases the refractive index, but if contained in excessive amounts, there is a tendency for dispersion to increase and Tg to rise. From the above viewpoints, the Ti ⁴⁺ content is preferably 10.0% or less, more preferably 9.0% or less, and further preferably 8.0% or less, 7.0% or less, 6.0% or less, 5.0% or less, 4.0% or less, 3.0% or less, and 2.0% or less in this order.

The W ⁶⁺ content may be 0.0%, 0.0% or more, or more than 0.0%. W ⁶⁺ is a component that increases the refractive index, but if it is contained in excess, there is a tendency for the dispersion to increase and the Tg to rise. From the above viewpoints, the W ⁶⁺ content is preferably 10.0% or less, more preferably 9.0% or less, and further preferably 8.0% or less, 7.0% or less, 6.0% or less, 5.0% or less, 4.0% or less, 3.0% or less, and 2.0% or less in this order.

The cation ratio of the total content of Li ⁺ and Na ⁺ to the total content of Li ⁺ and K ⁺ ((Li ⁺ +Na ⁺ )/(Li ⁺ +K ⁺ )) can exceed 0.00. From the perspective of maintaining the thermal stability of the glass, further lowering the Tg and improving the solubility of the glass, it is preferably above 0.50, more preferably above 0.55, and further preferably above 0.60, 0.65, 0.66, 0.67, 0.68, 0.69, 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, and 0.80, in this order. In addition, from the viewpoint of maintaining the thermal stability of the glass, further lowering the Tg and improving the solubility of the glass, the cation ratio ((Li ⁺⁺ Na ⁺ )/(Li ⁺⁺ K ⁺ )) is preferably less than 2.05, more preferably less than 2.00, and more preferably 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, less than 1.56, less than 1.55, less than 1.54, less than 1.53, less than 1.52, less than 1.51, and less than 1.50, in this order.

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

The cation ratio of Li ⁺ content to the total content of Li ⁺ and Na ⁺ (Li ⁺ /(Li ⁺ +Na ⁺ )) can exceed 0.00. From the perspective of maintaining the thermal stability of the glass, further lowering the Tg and improving the solubility of the glass, it is preferably above 0.05, more preferably above 0.10, and further preferably above 0.20, 0.25, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39 and 0.40, in this order. In addition, from the perspective of maintaining the thermal stability of the glass, further lowering the Tg and improving the solubility of the glass, the cation ratio (Li ⁺ /(Li ⁺⁺ Na ⁺ )) is preferably less than 1.00, more preferably less than 0.98, and more preferably less than 0.96, less than 0.94, less than 0.93, less than 0.92, less than 0.91, less than 0.90, less than 0.89, and less than 0.88 in this order.

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

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

From the perspective of maintaining the thermal stability of the glass, further lowering the Tg and improving the solubility of the glass, the cation ratio of the Na ⁺ content to the combined content of Na ⁺ and Li ⁺ (Na ⁺ /(Na ⁺ +Li ⁺ )) is preferably below 0.85, more preferably below 0.80, and further preferably below 0.75, below 0.74, below 0.73, below 0.72, below 0.71, below 0.70, below 0.69, below 0.68, below 0.67, below 0.66, and below 0.65, in this order. In addition, the cation ratio (Na ⁺ /(Na ⁺⁺ Li ⁺ )) can exceed 0.00. From the perspective of maintaining the thermal stability of the glass, further lowering the Tg and improving the solubility of the glass, it is preferably above 0.03, more preferably above 0.04, and further preferably above 0.05, 0.06, 0.07, 0.08, 0.09, and 0.10, in this order.

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

From the perspective of maintaining the thermal stability of the glass, further lowering the Tg and improving the solubility of the glass, the cation ratio of the Na ⁺ content to the combined content of Li ⁺ and K ⁺ (Na ⁺ /(Li ⁺⁺ K ⁺ )) is preferably less than 1.00, more preferably less than 0.98, and further preferably less than 0.96, less than 0.94, less than 0.92, less than 0.90, less than 0.88, less than 0.86, and less than 0.84, in this order. In addition, the cation ratio (Na ⁺ /(Li ⁺⁺ K ⁺ )) can exceed 0.00. From the perspective of maintaining the thermal stability of the glass, further lowering the Tg and improving the solubility of the glass, it is preferably above 0.03, more preferably above 0.05, and further preferably above 0.06, 0.07, 0.08, 0.09, 0.10, and 0.11, in this order.

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

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

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

From the viewpoint of further lowering Tg and suppressing the decrease in thermal stability of the glass, the cation ratio of R ²⁺ to Al ³⁺ content (R ²⁺ /Al ³⁺ ) is preferably 0.74 or less, more preferably 0.73 or less, and further preferably 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 or less, 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 this order. The cation ratio (R ²⁺ /Al ³⁺ ) may be 0.00, 0.00 or more, or more than 0.00. From the viewpoint of further lowering Tg and suppressing the decrease in 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 one embodiment, the optical glass may be a glass that does not contain S ⁶⁺ .

Pb, As, Cd, Tl, Be and Se are toxic, respectively, 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, so it is better not to contain these elements, that is, not to 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, so it is better not to be used as an element contained in the glass used for optical components. Therefore, it is better not to contain these elements, that is, not to introduce these elements into the glass as glass components.

Sb and Sn are elements that can be added optionally and function as clarifiers. 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, 0.02% or less, or 0.01% or less, based on the mass fraction (%) of Sb ₂ O ₃ when the mass of the glass is _100. On the other hand, the Sb content may be 0.00% or more, or 0.00%. 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, or 0.01% or less, based on the mass fraction (%) of SnO 2 when the mass of the glass is 100. On the other hand, the Sn content may be 0.00% or more, or may be 0.00%, in terms of the mass fraction (%) of SnO ₂ when the mass of the glass is set to 100.

The above describes the cationic components. Next, the anionic components will be described.

The optical glass contains at least ^F- as a cationic 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, and more preferably 21.0% or more, 22.0% or more, 23.0% or more, 24.0% or more, 25.0% or more, and 26.0% or more in this order. In addition, from the viewpoint of suppressing volatility 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 is further preferably 58.0% or less, 57.0% or less, 56.0% or less, 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, and 44.0% or less, in this order.

From the viewpoint of suppressing the increase of Tg, the O ^2- content is 83.0% or less, preferably 82.0% or less, and more preferably 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% or less, 74.0% or less, 73.0% or less, and 72.0% or less in this order. In addition, the O ^2- content may be 0.0%, 0.0% or more, or more than 0.0%. From the viewpoint of high refractive index and further improvement of thermal stability of glass, the ^O2- content is preferably 40.0% or more, more preferably 41.0% or more, and further preferably 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, 49.0% or more, 50.0% or more, 51.0% or more, 52.0% or more, 53.0% or more, and 55.0% or more in this order.

As anionic components other than the above, for example, Cl ^- , Br ^- and I ^- can be exemplified. The Cl ^- content can be, for example, 0.0%, 0.0% or more, more than 0.0%, 0.10% or more, 0.20% or more, and can be, for example, 5.0% or less, 4.0% or less, 3.0% or less, 2.0% or less, 1.0% or less, 0.50% or less. The Br ^- content can be, for example, 0.0%, 0.0% or more, more than 0.0%, 0.10% or more, 0.20% or more, and can be, for example, 5.0% or less, 4.0% or less, 3.0% or less, 2.0% or less, 1.0% or less, 0.5% or less. 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, and may be, for example, 5.0% or less, 4.0% or less, 3.0% or less, 2.0% or less, 1.0% or less, or 0.5% or less.

<Glass 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 under d-ray, F-ray, and C-ray, respectively. From the perspective 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, and more preferably 60.00 or more, 62.50 or more, 65.00 or more, 67.50 or more, 70.00 or more, 70.50 or more, 71.00 or more, 71.50 or more, 72.00 or more, 72.50 or more, and 73.00 or more in this order. In addition, the Abbe number νd of the optical glass may be, for example, 82.00 or less. In a projection optical system such as a photographic optical system or a projector, by combining lenses with different dispersion properties to form a bonded lens, chromatic aberration can be compensated and the optical system can be miniaturized. Low dispersion is generally easy to achieve with a plastic lens, so optical glass with low dispersion is useful as a material for optical elements constituting a projection optical system such as a photographic optical system or a projector. The above optical glass can exhibit low dispersion by having the above glass composition.

(Refractive index nd) From the perspective 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, or 1.450 or more. Alternatively, 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 the refractive index nd refers to the refractive index at a wavelength of 587.56nm.

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

(Specific gravity) From the perspective of reducing the weight of optical elements, it is preferred that the specific gravity of the optical glass is low. 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 better. Therefore, the lower limit is not particularly limited.

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

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

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 : glass thickness (mm), R(λ)＝((n(λ)－1)/(n(λ)＋1)) ² represents the reflectance at wavelength λ, and n(λ): refractive index at wavelength λ. The refractive index n(λ) at wavelength λ is measured at each wavelength in accordance with Japanese Industrial Standards (JIS Standards) JIS B 7071-1 "Determination of refractive index of optical glass - Part 1: Minimum deviation angle method".

<Method for manufacturing optical glass> The optical glass can be obtained as follows: weigh and mix phosphates, fluorides, oxides, carbonates, sulfates, nitrates, hydroxides, etc. as raw materials to obtain the target glass composition, fully mix them to make a mixed masterbatch, heat, melt, defoam, and stir them in a melting container to make a uniform and bubble-free molten glass, and shape it to obtain the optical glass. Specifically, it can be made using a known melting method.

[Glass raw material for pressure molding, optical element blank, and their manufacturing method] Another embodiment of the present invention relates to: Glass raw material for pressure molding containing the above-mentioned optical glass; and Optical element blank containing the above-mentioned optical glass.

According to another embodiment of the present invention, there are also provided: A method for manufacturing a glass raw material for press molding, which comprises a step of molding the optical glass into a glass raw material for press molding; A method for manufacturing an optical element blank, which comprises a step of press molding the glass raw material for press molding of the optical glass using a press molding mold to produce an optical element blank; and A method for manufacturing an optical element blank, which comprises a step of molding the optical glass into an optical element blank.

An optical element blank is an optical element base material that is similar in shape to a target optical element and to which a polishing material (a surface layer to be removed by polishing) and a grinding material (a surface layer to be removed by grinding) are added as needed. 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 a method (called a direct press method) of press-molding molten glass obtained by melting an appropriate amount of the above-mentioned glass. In another embodiment, the optical element blank can also be produced by solidifying molten glass obtained by melting an appropriate amount of the above-mentioned glass.

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

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

As for the glass raw materials for press molding, in addition to the raw materials which are directly provided to the press molding for manufacturing the optical element blanks in their original state and are called glass gobs for press molding, there are also raw materials which are provided to the press molding after being subjected to mechanical processing such as cutting, grinding, and polishing and passing through the glass gobs for press molding. As cutting methods, there are the following methods: a method of forming a groove on the portion to be cut on the surface of the glass plate by a method called scribing, a method of applying local pressure to the groove portion from the back side of the grooved surface, and cutting the glass plate at the grooved portion; a method of cutting the glass plate with a cutter, etc. In addition, as grinding and polishing methods, roller polishing, etc. can be cited.

The glass raw material for press molding can be produced by, for example, casting molten glass into a casting mold and forming it into a glass plate, and then cutting the glass plate into a plurality of glass sheets. Alternatively, a suitable amount of molten glass can be formed to produce a glass drop for press molding. It is also possible to produce an optical element blank by reheating and softening the glass drop for press molding and then press molding it. The method of reheating and softening the glass and then press molding it to produce an optical element blank is called a reheat press method in contrast to the direct press method.

[Optical element and method for manufacturing the same] Another embodiment of the present invention relates to: An optical element comprising the above optical glass. The above optical element is manufactured using the above optical glass. In the above optical element, one or more coating layers such as a multi-layer film such as an anti-reflection film may be formed on the glass surface.

In addition, according to an embodiment of the present invention, it is also possible to provide: A method for manufacturing an optical element having a process of manufacturing an optical element by grinding and/or polishing the above-mentioned optical element blank.

In the manufacturing method of the optical element, 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, an optical element with high internal and surface quality can be obtained. In this way, an optical element formed of the optical glass can be obtained. As optical elements, various lenses such as spherical lenses, aspherical lenses, micro lenses, prisms, etc. can be exemplified.

In addition, the optical element formed by the above optical glass is also suitable for use as a lens constituting a bonded optical element. As a bonded optical element, there can be exemplified an element formed by bonding lenses to each other (bonded lens), an element formed by bonding a lens and a prism, etc. For example, a bonded optical element can be produced by the following method: the bonding surfaces of the two optical elements to be bonded are precisely processed in such a way that their shapes become inverted shapes (for example, spherical polishing), and a UV-curable adhesive for bonding the bonding lenses is applied, and after they are bonded, UV rays are irradiated through the lens to cure the adhesive, thereby producing a bonded optical element. Multiple elements to be bonded can be produced separately using multiple types of glasses with different Abbe numbers νd, and bonded, thereby producing an element suitable for compensating for chromatic aberration. [Example]

The present invention is described in more detail below in conjunction with the embodiments. However, the present invention is not limited to the implementation methods shown in the embodiments.

[Example 1] <Sample No. 1~63> In order to obtain the glass composition shown in the table below, corresponding phosphates, fluorides, nitrates, sulfates, carbonates, hydroxides, oxides, boric acid, etc. were used as raw materials for introducing each component, and the raw materials were weighed and fully mixed to prepare a prepared raw material. The prepared raw material was placed in a platinum crucible, heated in a furnace set at 700~1100℃, and melted for 90 minutes. After stirring and homogenizing the molten glass, the molten glass was poured into a preheated mold, cooled naturally to near the glass transition temperature, and then immediately placed in an annealing furnace. After being kept at a temperature around the glass transition temperature for about 30 minutes, it was slowly cooled at a slow cooling rate of -30°C/hour for 4 hours, and then naturally cooled to room temperature in the furnace, thereby obtaining the optical glasses of Samples No. 1 to 63 shown in the following table.

[Comparative Example A, Comparative Example B] In order to obtain the glass composition shown in the table below, corresponding phosphates, fluorides, nitrates, sulfates, carbonates, hydroxides, oxides, boric acid, etc. were used as raw materials for introducing each component, and the raw materials were weighed and fully mixed to prepare a prepared raw material. The prepared raw material was placed in a platinum crucible, heated in a furnace set at 700~1100℃, and melted for 90 minutes. After stirring and homogenizing the molten glass, the molten glass was poured into a preheated casting mold, cooled naturally to near the glass transition temperature, and then immediately placed in an annealing furnace. After being kept at a temperature around the glass transition temperature for about 30 minutes, it was slowly cooled at a slow cooling rate of -30°C/hour for 4 hours, and then naturally cooled in the furnace to room temperature, thereby obtaining the optical glasses of Comparative Example A and Comparative Example B shown in the following table. Comparative Example A is equivalent to Example 33 of WO2003/037813 (Patent Document 1), and Comparative Example B is equivalent to Example 35 of WO2003/037813 (Patent Document 1).

<Physical property evaluation> The physical properties of each optical glass shown in the following table were measured by the following method.

(1) Refractive index nd, Abbe number νd The refractive index nd and Abbe number νd were measured for each optical glass using the refractive index measurement method specified by the Japan Optical Glass Industry Association. For Comparative Example A, the refractive index nd and Abbe number νd could not be measured because the glass was devitrified.

(2) Glass transition temperature Tg Glass was fully pulverized in a mortar and used as a sample. A platinum cell was used as a sample container. The glass transition temperature Tg was measured by a differential scanning calorimeter (DSC3300SA) manufactured by NETZSCH JAPAN Co., Ltd. at a heating rate of 10°C/min.

(3) Specific gravity The specific gravity was measured by the Archimedean method.

(4) Transmittance characteristics A test piece was cut out from the obtained glass, and both sides were mirror-polished to have parallel and optically polished planes, and the thickness was 10.0 mm. Then, the external transmittance at a wavelength of 500 to 1000 nm was measured using a spectrophotometer. In any of the examples of Samples No. 1 to 63, Comparative Example A, and Comparative Example B, it was confirmed that the external transmittance at a wavelength of 500 to 1000 nm was 80% or more and 100% or less when the thickness was 10.0 mm.

<Evaluation of thermal stability> For Samples No. 1 to 63, Comparative Example A and Comparative Example B, the corresponding phosphates, fluorides, nitrates, sulfates, carbonates, hydroxides, oxides, boric acid, etc. were used as raw materials for introducing each component in order to obtain the glass compositions shown in the table below. The raw materials were weighed and fully mixed to prepare the prepared raw materials. The prepared raw materials were placed in a platinum crucible, heated in a furnace set at 700 to 1100°C, and melted for 90 minutes. After the molten glass was stirred and homogenized, it was cast into a molding mold, molded, and slowly cooled to obtain a block-shaped glass sample. For the obtained glass sample, the crystals in the glass were observed using an optical microscope. The magnification of the optical microscope was set to 40 to 100 times. When no crystals were confirmed in the glass block, it was judged as A, when more than 1 and less than 15 crystals were confirmed per 1 ^cm3 on average, it was judged as B, when more than 16 and less than 40 crystals were confirmed per 1 ^cm3 on average, it was judged as C, and when more than 40 crystals were confirmed per 1 ^cm3 on average, it was judged as D. For A, B, and C, the thermal stability increases in the order of C→B→A, and A has the highest thermal stability. In the case of A, B, and C, it is the result that the internal quality of the number of crystals contained in the glass is within the allowable range during manufacturing. Glass judged as D lacks thermal stability and is glass with poor internal quality during manufacturing. As shown in the table below, it was confirmed that the thermal stability of the glasses of Samples No. 1 to 63 was excellent (judgment result A, B, or C).

(Example 2) Glass blocks (glass droplets) for press molding were produced using the various glasses obtained in Example 1. The glass droplets were heated and softened in the atmosphere, and then press molded using a press molding mold to produce a lens blank (optical element blank). The produced lens blank was taken out of the press molding mold, annealed, and subjected to mechanical processing including polishing to produce a spherical lens formed of the various glasses produced in Example 1.

(Example 3) The desired amount of molten glass produced in Example 1 was press-molded using a press-molding mold to produce a lens blank (optical element blank). The produced lens blank was taken out of the press-molding mold, annealed, and subjected to mechanical processing including polishing to produce a spherical lens formed of various glasses produced in Example 1.

(Example 4) A glass block (optical element blank) produced by solidifying the molten glass produced in Example 1 was annealed and subjected to mechanical processing including polishing to produce a spherical lens formed of various glasses produced in Example 1.

Finally, the above implementation methods are summarized.

[1] An optical glass, wherein, in a glass composition expressed in cation %, 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, the K ⁺ content exceeds 0.0 cation % and is 30.0 cation % or less, and the total content of Al3 ⁺ and ^P5+ (Al3 ⁺ +P5 ⁺ ) is 38.0 cation % or more and 70.0 cation % or less, wherein the total content of Li ⁺ , Na ⁺ , K ⁺ and Cs ⁺ is denoted as R ⁺ , and the total content of Be2 ⁺ , Mg2 ⁺ , Ca2 ⁺ , Sr2 ⁺ and Ba2 ⁺ is denoted as R2 ⁺ , 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, the cation ratio of Li ⁺ to the total content of R ⁺ and R ²⁺ (Li ⁺ /(R ⁺ +R ²⁺ )) is 0.29 or more, 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 content of Al ³⁺ and R ²⁺ (R ²⁺ /(Al ³⁺ +R ²⁺ )) is 0.37 or less, and in the glass composition expressed as anion %, O [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 greater than 0.50 and less than 1.59. [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 greater than 0.05 and less than 2.00. [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 greater than 0.05 and less than 1.00. [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 greater than 0.30 and less than 0.99. [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 greater than 0.10 and less than 5.00. [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 greater than 0.01 and less than 0.70. [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 greater than 0.10 and less than 0.80. [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 greater than 0.01 and less than 1.00. [13] The optical glass according to any one of [1] to [12], wherein the cation ratio of R ²⁺ to Al ³⁺ (R ²⁺ /Al ³⁺ ) is less than 0.74. [14] The optical glass according to any one of [1] to [13], wherein the glass transition temperature Tg is greater than 150°C and less than 355°C. [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 greater than 0.50 and less than 1.59, the cation ratio of the total content of Na ⁺ and K ⁺ to the total content of Li ⁺ and K ⁺ ((Na ⁺ +K ⁺ )/(Li ⁺ +K ⁺ )) is greater than 0.05 and less than 2.00, the cation ratio of the Li ⁺ content to the total content of Li ⁺ and Na ⁺ (Li ⁺ /(Li ⁺ +Na ⁺ )) is greater than 0.05 and less than 1.00, the cation ratio of the Li ⁺ content to the total content of Li ⁺ and K ⁺ (Li ⁺ /(Li ⁺ +K ⁺ )) is greater than 0.30 and less than 0.99, and Li ⁺ content to the total content of Na ⁺ and K ⁺ (Li ⁺ /(Na ⁺ +K ⁺ )) is 0.10 or more and 5.00 or less, the cation ratio of Na ⁺ content to the total content of Na ⁺ and Li ⁺ (Na + /(Na + +Li + )) is 0.85 or less, the cation ratio of Na + content to the total content of Na ⁺ and K + (Na + /(Na ⁺ +K ⁺ )) is 0.95 or less, the cation ratio of Na ⁺ content to the total content of Li ⁺ and K ⁺ (Na ⁺ /(Li ⁺ +K ⁺ )) is 1.00 or less, the cation ratio of K ⁺ content to the total content of K ⁺ and Li ⁺ (K ⁺ /(K ⁺ +Li ⁺ )) is 0.01 or more and 0.70 or less, the cation ratio of K + content to the total content of K + and Na + is 1.00 or less, the cation ratio of K ⁺ content to the total content of K ⁺ and Li ⁺ is 1.00 or less, the cation ratio of K ⁺ content to the total content of K + and Li + is 1.00 or less, the cation ratio of K + content to the total content of K ⁺ and Li ⁺ is 1.00 or less, the cation ratio of K ⁺ content to the total content of K ⁺ and Li + is 1.01 or more and 1. ^{[ 16]} An ^optical element comprising ^the optical glass ^{described in} any one ^{of [ 1 ]} to ^{[ 15 ] .}

It should be understood that the embodiments disclosed this time are all exemplary and do not constitute limitations. The scope of the present invention is limited by the scope of the patent application, not the above description, and is intended to include all variations within the meaning and scope equivalent to the claim. For example, for the glass composition exemplified above, by adjusting the composition described in the specification, an optical glass of one embodiment of the present invention can be obtained. In addition, of course, any combination of two or more of the items exemplified in the specification or described as a preferred scope can be used.

without

without

Claims (14)

An optical glass, in which, in a glass composition expressed in cation %, a Li ⁺ content exceeds 0.0 cation % and is 48.0 cation % or less, a Na ⁺ content exceeds 0.0 cation % and is 35.0 cation % or less, a K ⁺ content exceeds 0.0 cation % and is 30.0 cation % or less, and a total content of Al3 ⁺ and P5 ⁺ (Al3 ⁺ +P5 ⁺ ) is 38.0 cation % or more and 70.0 cation % or less, wherein the total content of Li ⁺ , Na ⁺ , K ⁺ and Cs ⁺ is R ⁺ , and the total content of Be2 ⁺ , Mg2 ⁺ , Ca2 ⁺ , Sr2 ⁺ and Ba2 ⁺ is R2 ⁺ , R ⁺ relative to the total content of Al ³⁺ and P ⁵⁺ (R ⁺ /(Al ³⁺ +P ⁵⁺ )) is 0.93 or more, the cation ratio of the Li ⁺ content relative to the total content of R ⁺ and R ²⁺ (Li ⁺ /(R ⁺ +R ²⁺ )) is 0.29 or more, the cation ratio of R ²⁺ relative to the Al ³⁺ content (R ²⁺ /Al ³⁺ ) is 0.40 or less, the cation ratio of the total content of Li ⁺ and K ⁺ relative 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⁺ relative to the total content of Al ³⁺ and R ²⁺ (R ²⁺ /(Al ³⁺ +R ^{2+ )} ) is 0.6 )) is less than 0.37, the cation ratio of the total content of Li ⁺ and Na ⁺ to the total content of Li ⁺ and K ⁺ ((Li ⁺ +Na ⁺ )/(Li ⁺ +K ⁺ )) is greater than 0.50 and less than 1.59, in the glass composition expressed in anion %, the ^O2- content is less than 83.0 anion %, the ^F- content is greater than 19.0 anion %, and the external transmittance of the optical glass at a wavelength of 500nm~1000nm is greater than 80% when converted to a thickness of 10.0mm. The optical glass according to claim 1, wherein a cation ratio of a total content of Na ⁺ and K ⁺ to a total content of Li ⁺ and K ⁺ ((Na ⁺ +K ⁺ )/(Li ⁺ +K ⁺ )) is greater than or equal to 0.05 and less than or equal to 2.00. The optical glass according to claim 1, wherein a cation ratio of the Li ⁺ content to the total content of Li ⁺ and Na ⁺ (Li ⁺ /(Li ⁺ +Na ⁺ )) is greater than or equal to 0.05 and less than or equal to 1.00. The optical glass according to claim 1, wherein a cation ratio of the Li ⁺ content to the total content of Li ⁺ and K ⁺ (Li ⁺ /(Li ⁺ +K ⁺ )) is greater than or equal to 0.30 and less than or equal to 0.99. The optical glass according to claim 1, wherein a cation ratio of the Li ⁺ content to the total content of Na ⁺ and K ⁺ (Li ⁺ /(Na ⁺ +K ⁺ )) is greater than or equal to 0.10 and less than or equal to 5.00. The optical glass according to claim 1, wherein a 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 a 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 a 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 a cation ratio of the K ⁺ content to the total content of K ⁺ and Li ⁺ (K ⁺ /(K ⁺ +Li ⁺ )) is greater than or equal to 0.01 and less than or equal to 0.70. The optical glass according to claim 1, wherein a cation ratio of K ⁺ content to a total content of K ⁺ and Na ⁺ (K ⁺ /(K ⁺ +Na ⁺ )) is greater than or equal to 0.10 and less than or equal to 0.80. The optical glass according to claim 1, wherein a cation ratio of K ⁺ content to a total content of Li ⁺ and Na ⁺ (K ⁺ /(Li ⁺ +Na ⁺ )) is greater than or equal to 0.01 and less than or equal to 1.00. The optical glass according to claim 1 has a glass transition temperature Tg of 150° C. or higher and 355° C. or lower. The optical glass as described in 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 ⁺ )) is 0.05 to 2.00, the cation ratio of the Li ⁺ content to the total content of Li ⁺ and Na ⁺ (Li ⁺ /(Li ⁺ +Na ⁺ )) is 0.05 to 1.00, the cation ratio of the Li ⁺ content to the total content of Li ⁺ and K ⁺ (Li ⁺ /(Li ⁺ +K ⁺ )) is 0.30 to 0.99, the cation ratio of the Li ⁺ content to the total content of Na ⁺ and K ⁺ (Li ⁺ /(Na ⁺ +K ⁺ )) is 0.10 to 5.00, and the Na ⁺ content to the total content of Na ⁺ and Li ⁺ is less than 0.85, the cation ratio of ^{Na + content} to the total content of Na ⁺ and K ⁺ (Na ^{+ /} (Na ⁺ +K ^{+ )} ) is less than 0.95, the cation ratio of Na ⁺ content to the total content of Li ⁺ and K ⁺ (Na ⁺ /(Li ⁺ +K ⁺ )) is less than 1.00, the cation ratio of K ⁺ content to the total content of K ⁺ and Li ⁺ (K ⁺ /(K ⁺ +Li ⁺ )) is 0.01 to 0.70, the cation ratio of K ⁺ content to the total content of K ⁺ and Na ⁺ (K ⁺ /(K ⁺ +Na ⁺ )) is 0.10 to 0.80, the cation ratio of K ⁺ content to the total content of Li ⁺ and Na + is 1.00 to 1.00, The cation ratio of the total content of K ^{+ /} (Li ⁺ +Na ⁺ ) is greater than or equal to 0.01 and less than or equal to 1.00, and the glass transition temperature Tg of the optical glass is greater than or equal to 150° C. and less than or equal to 355° C. An optical element comprising the optical glass as described in any one of claims 1 to 13.