TWI735451B - Glass, optical glass, glass materials for polishing, glass materials for press molding, and optical components - Google Patents

Abstract

The present invention provides a glass which can shorten the heat treatment time when heat treatment is used to reduce the reduced color of the glass. A glass whose Abbe number ( v _d ) is 18.10 or less; the total content of _{TiO 2} , Nb ₂ O ₅ , WO ₃ and Bi ₂ O _{3 [TiO 2} +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ ] Is 30% by mass or more; and _{phosphate glass with a Bi 2} O ₃ content of 38% by mass or less; the mass of the content of Li ₂ O and the total content of TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ The ratio [Li ₂ O/(TiO ₂ +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ )] multiplied by 100 is 0.015 to 0.770.

Description

Glass, optical glass, glass materials for polishing, glass materials for press molding, and optical components

The present invention relates to a glass, an optical glass, a glass material for polishing, a glass material for press molding, and an optical element that can easily reduce the reduction color.

In recent years, there has been an increasing demand for high-dispersion glass as a material for optical elements that are effective for high-functionality and compactness of devices such as photographic optical systems and projection optical systems. For example, a lens made of high-dispersion glass is combined with a lens made of low-dispersion glass to form a pair of lenses and used to correct chromatic aberrations.

High-dispersion glass generally contains a large amount of components such as TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ (hereinafter sometimes referred to as "high-dispersion component") as a glass component. These high-dispersion components are easily reduced during the melting of the glass. When the high-dispersion component is reduced, light on the short-wavelength side of the visible light region is absorbed to color the glass (hereinafter, sometimes referred to as "reduced color").

In Patent Document 1, the coloring of such glass is reduced by heat-treating the glass. It is considered that this is because the Ti, Nb, W, and Bi plasmas in the reduced state are oxidized by heating, and the visible light absorption is weakened.

That is, for high-dispersion glass containing a large amount of _{high-dispersion components such as TiO 2} , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ as the glass component, heat treatment is used to reduce the reduced color, thereby obtaining the required transparency. However, this heat treatment requires a long time to heat the glass, and therefore, improvement is required from the viewpoints of productivity and economy. In particular, for high-dispersion glass having an Abbe number (v _d ) of 18.1 or less, the coloration is denser, so the heat treatment for reducing the coloration requires a long time.

[Prior Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Application Laid-Open No. 6-345481.

The present invention has been completed in view of such actual circumstances, and its object is to provide a glass whose heat treatment time can be shortened when heat treatment is used to reduce the reduced color.

The inventors of the present application have conducted intensive studies to achieve the above-mentioned object, and as a result, found that the high-dispersion component contains Li ₂ O at a predetermined ratio, thereby achieving the object. Based on this knowledge, the present invention has been completed.

If Li ₂ O is contained as a glass component, the Abbe number ( v _d ) increases, and the thermal stability of the glass decreases. _{Therefore, Li 2} O is usually not contained in high-dispersion glass.

For the high-dispersion glass of the present invention, the Abbe number ( v _d ) is lowered to maintain high dispersion, and Li ₂ O is contained as a glass component, which can shorten the reduction of TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi The heat treatment time required for the reduction of color caused by high dispersion components such as ₂ O _3.

_{If an alkali metal oxide such as Li 2} O is contained as a glass component, the melting temperature is lowered, and the glass transition temperature (Tg) is also lowered with this. _{In the conventional precision press glass, Li 2} O may be contained in order to lower the glass transition temperature (Tg) and facilitate processing. _{Here, for the glass containing Li 2} O in order to lower the glass transition temperature (Tg), since the melting temperature is low, the reduction reaction of the high-dispersion component basically does not proceed in the melting process, so the degree of coloration of the glass is light and not A long heat treatment is required. _{Therefore, when Li 2} O is contained in order to lower the melting temperature like the conventional glass, there is no need for long-term heat treatment to the extent that it affects the production process. Therefore, it has not been recognized that the reduction of the reduced color is required. The subject of heat treatment time.

The present invention is based on the discovery that the reduced color caused by high dispersion components such as _{TiO 2} , Nb ₂ O ₅ , WO ₃ and Bi ₂ O _{3 is a problem for high dispersion glass.} The invention in which the contained Li ₂ O can shorten the heat treatment time required to reduce the reduced color is an invention that utilizes an extremely novel effect as an effect obtained _{by containing Li 2 O as a glass component.}

That is, the gist of the present invention is as follows.

[1] A glass having an Abbe number ( v _d ) of 18.10 or less; the total content of _{TiO 2} , Nb ₂ O ₅ , WO ₃ and Bi ₂ O _{3 [TiO 2} +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ ] is 30% by mass or more; and _{phosphate glass with a Bi 2} O ₃ content of 38% by mass or less.

Li ₂ O content of TiO _2, Nb ₂ O _5, mass of the total content of WO ₃ and Bi ₂ O ₃ ratio of _{[Li 2 O / (TiO 2 +} Nb 2 O 5 + WO 3 + Bi 2 O 3) ] The value multiplied by 100 is 0.015 ~ 0.770.

[2] A glass having an Abbe number ( v _d ) of 18.10 or less; a phosphate glass containing at least one oxide selected from the group consisting of TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O _3.

It will be melted for another 90 minutes at a temperature higher than the liquidus temperature (LT) 110~120℃ in an atmospheric atmosphere and molded, and in an atmospheric atmosphere at a holding temperature 0~20℃ lower than the glass transition temperature (Tg) Hold for 15 minutes and slowly cool to a temperature 120°C lower than the above holding temperature at a cooling rate of 30°C/h. The glass is processed into a glass with a length of 17mm, a width of 13mm, and a thickness of 10mm; when viewed from above, it is at one end from the longitudinal direction The part in the range of 0~5mm and the distance of 0~5mm from the horizontal end is set as the glass end, which is 6~11mm from the vertical end and 4~9mm from the horizontal end when viewed from above. When the part of the distance range is set as the center part of the glass; the heat treatment and the heat treatment which are heated at a heating rate of 100°C/h in an atmospheric atmosphere and maintained at a heat treatment temperature 5-15°C lower than the glass transition temperature (Tg) Slow cooling at a temperature drop rate of 30°C/h to a temperature 120°C lower than the heat treatment temperature is performed once or repeatedly until the end of the glass at the wavelength of 656nm when light is incident parallel to the thickness direction The external transmittance (T _A ) and the external transmittance (T _{B ) at the center of the glass are more than the value (T 1} ) calculated by the following formula (2), and the external transmittance (T _A ) at the end of the glass The difference (T _A- T _B ) from the external transmittance (T _B ) of the center portion of the glass is 5% or less. In this case, the total time during which the heat treatment temperature is maintained in the heat treatment is within 48 hours.

T ₁ =0.83×{1-{(n _C -1)/(n _C +1)} ² } ² ×98. . . Formula (2)

[In formula (2), n _C is the difference (T _A -T _B ) _{between the external transmittance (T A} ) of the end of the glass and the external transmittance (T _B ) of the center of the glass after the heat treatment and slow cooling treatment are performed. The refractive index at a wavelength of 656.27 nm when it is 5% or less. ]

[3] The glass according to [1] or [2], wherein _{the content of Li 2} O is 0.010% by mass or more.

[4] The glass according to any one of [1] to [3], wherein _{the content of Li 2} O is 0.640% by mass or less.

[5] The glass according to any one of [1] to [4], wherein the value of βOH represented by the following formula (1) is 0.05 mm ^-1 or more.

βOH=-〔ln(D/C)〕/t. . . Formula 1)

[In formula (1), t represents the thickness (mm) of the glass used in the measurement of external transmittance, and C represents the external transmittance (%) at a wavelength of 2500 nm when light is incident on the glass parallel to its thickness direction, D represents the external transmittance (%) at a wavelength of 2900 nm when light is incident on the glass parallel to its thickness direction. ]

[6] The glass according to any one of [1] to [5], which contains Nb ₂ O ₅ as a glass component.

[7] The glass according to any one of [1] to [6], which contains TiO ₂ as a glass component.

[8] An optical glass formed of the glass described in any one of [1] to [7] above.

[9] A glass material for polishing, formed of the glass described in any one of [1] to [7] above.

[10] A glass material for press molding, formed of the glass described in any one of [1] to [7] above.

[11] A glass material for polishing, comprising the optical fiber described in [8] above The glass is formed.

[12] A glass material for press molding, which is formed of the optical glass described in [8] above.

[13] An optical element formed of the glass described in any one of [1] to [7] above.

[14] An optical element formed of the optical glass described in [8] above.

[15] An optical element formed of the glass material for polishing described in [9] or [11] above.

[16] An optical element formed of the glass material for press molding as described in [10] or [12] above.

According to the present invention, the heat treatment time can be shortened when the high dispersion glass is heat treated to reduce the reduced color.

Hereinafter, a mode for implementing the present invention (hereinafter simply referred to as "embodiment") will be described in detail. The following embodiment is an illustration for explaining the present invention, and its purpose is not to limit the present invention to the following content. The present invention can be suitably modified and implemented within the scope of the subject matter. Furthermore, the description of the repeated description may be omitted as appropriate, but this does not limit the gist of the invention. It should be noted that in this specification, "glass" is a glass composition containing a plurality of glass constituents (glass components), and unless otherwise specified, it is defined as a glass composition related to the shape (block shape, Plate shape, spherical shape, etc.), applications (materials for optical elements, optical elements, etc.), and general terms irrespective of size are used. That is, the shape, use, and size of glass are not limited, and glass of any shape, glass of any other purpose, and glass of any size are included in the glass of the present invention.

In addition, in this specification, (numerical value 1) may be used to express a numerical range as "(numerical value 1) or less". The range indicated in this way is the numerical range smaller than (numerical value 1) plus the numerical range of (numerical value 1). The numerical range indicated by "less than (numerical value 1)" is a numerical range smaller than (numerical value 1), and does not include (numerical value 1). Sometimes (numerical value 2) is used to express the numerical range as "(numerical value 2) or more". The range represented in this way is the numerical range greater than (numerical value 2) plus the numerical range of (numerical value 2). Sometimes the numerical range is expressed as "exceeding (numerical value 2)". The range indicated in this way is a numerical range greater than (numerical value 2) and does not include (numerical value 2).

Regarding the present invention, in the first embodiment, the description is mainly based on the content of each glass component expressed in mass %, and in the second embodiment, the description is based on the transmittance during heat treatment. Hereinafter, unless otherwise specified, "%" means mass %. In addition, for some glass components, the content expressed in cation% is also described.

In this specification, the so-called mass% expression means that for each glass component represented by oxides and fluorides, the content of each glass component when the total content of all glass components is set to 100 mass% is expressed in mass percentage To represent. In addition, the so-called total content expressed in mass% refers to the total amount of the content of a plurality of glass components (including the case where the content is 0%). In addition, the mass ratio refers to the ratio (ratio) of the contents of the glass components (including the total contents of a plurality of components) expressed in mass %.

In addition, in the present specification, the expression expressed in cationic% means the molar percentage when the total content of all cationic components is set to 100%. The total content expressed in cationic% refers to the total amount of the content of a plurality of cationic components (including the case where the content is 0%). In addition, the term "cation ratio" refers to the ratio (ratio) of the content of the cation components (including the total content of a plurality of cation components) when expressed in cation %.

It should be noted that the valence of the cation component (for example, the valence of P ⁵⁺ is +5, ^{the valence of Si 4+} is +4, and ^{the valence of La 3+} is +3) is a value determined according to conventional methods, and is used to oxidize When P, Si, and La as glass components are expressed on a physical basis, it is the same as expressing P ₂ O ₅ , SiO ₂ , and La ₂ O ₃ . Therefore, when analyzing the glass composition, it is not necessary to analyze the valence of the cationic component. In addition, the valence of the anion component (for example, the valence of O ^2- is -2) is also a value that is conventionally determined, and the oxide-based glass component is expressed as, for example, P ₂ O ₅ , SiO ₂ , La _{2 as described above.} O ₃ is the same. Therefore, when analyzing the glass composition, it is not necessary to analyze the valence of the anion component.

As described later, a small amount of Sb ₂ O ₃ , SnO ₂ , and CeO _{2 may} be added as a fining agent to the glass. _{However, in this specification, each content of Sb 2} O ₃ , SnO ₂ , and CeO ₂ is not included in the total content of all glass components. That is, the glass component of _{Sb 2 O 3, SnO 2,} CeO ₂ content is represented by each of Sb ₂ O _3, the total amount of all the components other than the glass of SnO ₂ and CeO ₂ in the Sb ₂ O _3, SnO ₂ , CeO ₂ content. In this specification, such expressions are referred to as additional.

In the glass according to the embodiment of the present invention, _{the content of Li 2} O is quantified by ICP-MS (Inductively Coupled Plasma-Mass Spectrometry), and _{the content of glass components other than Li 2} O is measured by ICP-AES (Inductively Coupled Plasma-Mass Spectrometry). Atomic Emission Spectrometry) to quantify. The analysis value obtained by ICP-AES may include, for example, a measurement error of about ±5% of the analysis value. In addition, in this specification and the present invention, the content of the constituent components of the glass being 0% or not containing means that the constituent components are not substantially contained, and that the content of the constituent components is equal to or less than the impurity level.

The first embodiment

The glass of the first embodiment of the present invention has an Abbe number ( v _d ) of 18.10 or less; the total content of _{TiO 2} , Nb ₂ O ₅ , WO ₃ and Bi ₂ O _{3 [TiO 2} +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ ] is 30% by mass or more; and _{a phosphate glass with a Bi 2} O ₃ content of 38% by mass or less, in which _{the content of Li 2} O is the same as that of TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O The mass ratio of the total content of _{3 [Li 2} O/(TiO ₂ +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ )] multiplied by 100 is 0.015 to 0.770.

Hereinafter, the glass according to the first embodiment will be described in detail.

In the glass according to the first embodiment, the Abbe number ( v _d ) is 18.10 or less. The upper limit of the Abbe number ( v _d ) is preferably 18.05, and more preferably 18.00, 17.90, 17.80, 17.70, 17.60, 17.50, 17.40, 17.30, 17.20, 17.10, 17.00, 16.90, 16.80, 16.78 in order. In addition, the lower limit of the Abbe number is preferably 15.00, and more preferably 15.10, 15.20, 15.25, 15.30, 15.35, 15.40, 15.45, 15.50, 15.52, 15.54, 15.56, 15.58, and 15.60 in this order.

By setting the Abbe number ( v _d ) to 18.10 or less, when it is combined with a low-dispersion glass lens to form a pair lens, the difference in Abbe number becomes large, and a high effect is achieved in chromatic aberration correction.

In the glass according to the first embodiment, the total content of _{TiO 2} , Nb ₂ O ₅ , WO ₃ and Bi ₂ O _{3 [TiO 2} +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ ] is 30% or more . The lower limit of the total content [TiO ₂ +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ ] is preferably 35%, and more preferably 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%. In addition, the upper limit of the total content [TiO ₂ +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ ] is preferably 90%, and more preferably 88%, 86%, 85%, 84%, 83%, 82%. %, 81%, 80%, 79%, 78%, 77%.

TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ contribute to the high dispersion of glass. In addition, by containing it in an appropriate amount, it also has an effect of improving the thermal stability of the glass. Therefore, the lower limit of the total content [TiO ₂ +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ ] is preferably the above range. On the other hand, TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ increase the coloring of the glass. Therefore, the upper limit of the total content [TiO ₂ +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ ] is preferably within the above range.

In addition, in the glass according to the first embodiment, if the content of the glass component is expressed in cationic %, the total content of ^{Ti 4+} , Nb ⁵⁺ , W ⁶⁺ and Bi ^{3+ [Ti 4+} +Nb ⁵⁺ The upper limit of +W ⁶⁺ +Bi ³⁺ ] is preferably 75.00 cationic%, and more preferably 74.50 cationic%, 74.00 cationic%, 73.50 cationic%, 73.00 cationic%, 72.50 cationic%, 72.00 cationic%, 71.50 cationic% , 71.00 cationic%, 70.50 cationic%. The lower limit of the total content [Ti ⁴⁺ +Nb ⁵⁺ +W ⁶⁺ +Bi ³⁺ ] is preferably 52.00 cationic%, and more preferably 52.10 cationic%, 52.15 cationic%, 52.20 cationic%, 52.25 cationic%, 52.30 cation%.

Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ contribute to the high dispersion of glass. In addition, by containing it in an appropriate amount, it also has an effect of improving the thermal stability of the glass. Therefore, the lower limit of the total content [Ti ⁴⁺ +Nb ⁵⁺ +W ⁶⁺ +Bi ³⁺ ] is preferably the above range. On the other hand, Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ increase the coloring of the glass. Therefore, the upper limit of the total content [Ti ⁴⁺ +Nb ⁵⁺ +W ⁶⁺ +Bi ³⁺ ] is preferably the above range.

In the glass according to the first embodiment, _{the content of Bi 2} O ₃ is 38% or less. The upper limit of the content of Bi ₂ O ₃ is preferably 35%, and more preferably 33%, 30%, 28%, 25%, 23%, 20% in order. In addition, the lower limit of the content of _{Bi 2} O _{3 is preferably 0%.} The content of Bi ₂ O ₃ may be 0%.

Bi ₂ O ₃ is a component that contributes to high dispersion. In addition, by setting _{the content of Bi 2} O ₃ in the above range, it is possible to suppress an increase in specific gravity and a decrease in glass transition temperature (Tg). When the specific gravity of the glass increases, the quality of the optical element increases. For example, if a high-quality lens is assembled into an auto-focus type photographic lens, the power required to drive the lens during auto-focusing will increase, and battery consumption will increase. Therefore, it is preferable to _{set the content of Bi 2} O ₃ within the above-mentioned range.

In addition, Bi ₂ O ₃ has the effect of greatly increasing the refractive index compared with other high-dispersion components TiO ₂ , Nb ₂ O ₅ , and WO _3. If the refractive index is greatly increased, when it is combined with a low-dispersion glass lens with a low refractive index to correct chromatic aberration, the refractive index difference is large, and therefore it is easy to strongly express curvature of field. Therefore, it is preferable to _{set the content of Bi 2} O ₃ within the above-mentioned range.

In addition, in the glass according to the first embodiment, when the content of the glass component is expressed in cationic %, ^{the upper limit of the Bi 3+} content is preferably 10.00 cationic%, and more preferably 9.00 cationic%, 8.00 cationic%, 7.00 cationic%, 6.00 cationic%, 5.00 cationic%, 4.50 cationic%, 4.00 cationic%, 3.50 cationic%, 3.00 cationic%, 2.50 cationic%, 2.00 cationic%, 1.50 cationic%, 1.00 cationic%. The content of Bi ³⁺ can be 0 cationic %.

Bi ³⁺ is a component that contributes to high dispersion. In addition, by setting ^{the content of Bi 3+} in the above range, it is possible to suppress an increase in specific gravity and a decrease in the glass transition temperature (Tg). When the specific gravity of the glass increases, the quality of the optical element increases. For example, if a high-quality lens is assembled into an auto-focus type photographic lens, the power required to drive the lens during auto-focusing will increase, and battery consumption will increase. Therefore, it is preferable to ^{set the content of Bi 3+} to the above-mentioned range.

In addition, Bi ³⁺ has an effect of greatly increasing the refractive index compared with other high-dispersion components Ti ⁴⁺ , Nb ⁵⁺ , and W ^6+. If the refractive index is greatly increased, when it is combined with a low-dispersion glass lens with a low refractive index to correct chromatic aberration, the refractive index difference is large, and therefore it is easy to strongly express curvature of field. Therefore, it is preferable to ^{set the content of Bi 3+} in the above-mentioned range.

The glass according to the first embodiment is phosphate glass. The so-called phosphate glass refers to a glass mainly containing phosphate as a network forming component of the glass. Therefore, the glass according to the first embodiment mainly contains phosphate as a network forming component, and its content is expressed _{as the content of P 2} O _5. As a network forming component of glass, P ₂ O ₅ , Al ₂ O ₃ , B ₂ O ₃ , SiO ₂ and the like are known. Here, the so-called glass mainly containing phosphate as a network forming component means that _{the content of P 2} O ₅ expressed by mass% is greater than the content of any one of _{Al 2} O ₃ , B ₂ O ₃ , and SiO ₂ .

In the glass according to the first embodiment, _{the lower limit of the content of P 2} O ₅ is preferably 7.0%, and more preferably 8.0%, 9.0%, 10.0%, 11.0%, 12.0%, 13.0%, and 14.0% in order , 15.0%, 16.0%, 17.0%, 18.0%, 19.0%, 20.0%. In addition, _{the upper limit of the content of P 2} O ₅ is preferably 37.0%, and more preferably 36.0%, 35.0%, 34.5%, 34.0%, 33.5%, 33.0%, 32.5%, 32.0%, 31.5%, 31.0% in order. , 30.5%, 30.0%.

P ₂ O ₅ is a component necessary for the glass to contain a large amount of high-dispersion components. On the other hand, if P ₂ O ₅ is contained excessively, the meltability will deteriorate. Therefore, in the glass according to this embodiment, it is preferable to _{set the content of P 2} O ₅ in the above-mentioned range.

In addition, in the glass according to the first embodiment, when the content of the glass component is expressed in cationic %, ^{the upper limit of the content of P 5+} is preferably 42.00 cationic%, and more preferably 41.50 cationic%, 41.00 cationic%, 40.50 cationic%, 40.00 cationic%, 39.50 cationic%, 39.00 cationic%, 38.50 cationic%, 38.00 cationic%, 37.50 cationic%, 37.00 cationic%, 36.50 cationic%, 36.00 cationic%. The lower limit of the content of P ⁵⁺ is preferably 25.00 cationic%, and more preferably 25.50 cationic%, 26.00 cationic%, 26.50 cationic%, 27.00 cationic%, 27.50 cationic%, 28.00 cationic%, 28.50 cationic%, 29.00 cationic% in order. , 29.30 positive ion%.

P ⁵⁺ is a component necessary to suppress the increase in refractive index n _d and to contain a large amount of high-dispersion components in the glass. On the other hand, if P ⁵⁺ is contained excessively, the solubility will deteriorate. Therefore, in the optical glass according to this embodiment, it is preferable to ^{set the content of P 5+} in the above-mentioned range.

In the glass of the first aspect related to the, Li ₂ O content and the _{2, 2} O _5, the total content of WO ₃ and Bi ₂ O ₃ of Nb TiO mass ratio of _{[Li 2 O / (TiO 2 +} Nb 2 O ₅ +WO ₃ +Bi ₂ O ₃ )] multiplied by 100 is 0.015 to 0.770. The lower limit of the mass ratio [Li ₂ O/(TiO ₂ +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ )] multiplied by 100 is preferably 0.017, and more preferably 0.019, 0.021, 0.023, 0.025, 0.027, 0.030. In addition, the upper limit of the mass ratio [Li ₂ O/(TiO ₂ +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ )] multiplied by 100 is preferably 0.750, and more preferably 0.730, 0.710, 0.700, 0.680, 0.650, 0.600, 0.550.

By setting the mass ratio [Li ₂ O/(TiO ₂ +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ )] multiplied by 100 to the above range, the reduction in coloration by heat treatment can be sufficiently promoted. If the mass ratio [Li ₂ O/(TiO ₂ +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ ) multiplied by 100 exceeds 0.750, the desired high dispersion characteristics cannot be obtained, and the stability of the glass will be impaired sex.

In the glass according to the first embodiment, when the content of the glass component is expressed in cationic %, when the content of W ⁶⁺ exceeds 0 cationic %, the cationic ratio of the content of ^{Ba 2+ to} the content of W ^{6+ [} The upper limit of Ba ²⁺ /W ⁶⁺ ] is preferably 0.14, and more preferably 0.13, 0.12, 0.11, and 0.10 in this order.

Ba ²⁺ is a component that contributes to low dispersion. Therefore, in the glass according to the first embodiment ^{, W 6+} as a high-dispersion component ^{relative to the content of Ba 2+} is contained so as to have the above-mentioned cation ratio, so that the desired high-dispersibility can be maintained.

In addition, in the glass according to the first embodiment, when the content of the glass component is expressed in cationic %, when ^{the content of W 6+} is 0 cationic% and ^{the content of Ba 2+} exceeds 0 cationic %, Ti ⁴⁺ The upper limit of the total content of Bi ^{3+ [Ti 4+} +Bi ³⁺ ] is preferably 35.00 cationic%, and more preferably 34.00 cationic%, 33.00 cationic%, 32.50 cationic%, 32.30 cationic%, 32.00 cationic%, 31.80 cationic%, 31.60 cationic%, 31.40 cationic%, 31.20 cationic%, 31.00 cationic%, 30.80 cationic%, 30.60 cationic%, 30.40 cationic%, 30.20 cationic%, 30.10 cationic%, 30.00 cationic%. The lower limit of the total content [Ti ⁴⁺ +Bi ³⁺ ] is preferably 21.00 cationic%, and more preferably 21.20 cationic%, 21.40 cationic%, 21.60 cationic%, 21.80 cationic%, 22.00 cationic%, 22.20 cationic%, 22.40 Cationic%, 22.60 cationic%, 22.80 cationic%, 23.00 cationic%, 23.10 cationic%, 23.20 cationic%, 23.30 cationic%, 23.40 cationic%, 23.50 cationic%.

In ^{the case where the content of W 6+} is 0 cationic% and ^{the content of Ba 2+ exceeds 0 cationic %, Ti 4+} , which is second only to W ⁶⁺ in the high-dispersion components, contributes to high-dispersion, and has improved ^{By setting the total content of Bi 3+} as a function of thermal stability in the above range, it is possible to suppress the decrease in dispersion ^{due to Ba 2+.}

(Glass composition)

The preferred mode of the glass according to the first embodiment described above will be described in detail below.

In the glass according to this embodiment, _{the lower limit of the content of Li 2} O is preferably 0.010%, and more preferably 0.012%, 0.014%, 0.016%, 0.018%, and 0.020% in this order. The upper limit of the content of Li ₂ O is preferably 0.640%, and more preferably 0.630%, 0.620%, 0.610%, 0.600%, 0.580%, 0.560%, 0.540%, 0.520%, 0.500%, 0.490%, 0.480% in order. , 0.470%, 0.460%, 0.450%, 0.440%, 0.430%, 0.420%, 0.410%, 0.400%, 0.390%, 0.380%, 0.370%, 0.360%, 0.350%, 0.340%.

By setting _{the content of Li 2} O in the above range, the heat treatment time required to reduce the reduced color caused by high dispersion components such as _{TiO 2} , Nb ₂ O ₅ , WO ₃ and Bi ₂ O _{3 can be shortened.} Furthermore, it is possible to suppress the decrease in the glass transition temperature (Tg). On the other hand, if _{the content of Li 2} O is too large, the Abbe number ( v _d ) increases, and the thermal stability of the glass may decrease.

In the present embodiment, the glass covered, the preferred lower limit value βOH represented by the following formula (1) is 0.05mm ^-1, further more preferably sequentially 0.10mm ^-1, 0.15mm ^-1, 0.20mm ^{- 1.} 0.25mm ^-1 , 0.30mm ^-1 , 0.35mm ^-1 . In addition, the upper limit of the value of βOH is preferably 4.00mm ^-1 , and more preferably 3.90mm ^-1 , 3.80mm ^-1 , 3.70mm ^-1 , 3.60mm ^-1 , 3.50mm ^-1 , 3.40mm ^-1 , 3.30mm ^-1 , 3.20mm ^-1 , 3.10mm ^-1 , 3.00mm ^-1 , 2.90mm ^-1 , 2.80mm ^-1 , 2.70.mm ^-1 , 2.60mm ^-1 , 2.50mm ^-1 , 2.40mm ^{-1 , 2.30mm -1, 2.25mm -1, 2.20mm} -1, 2.10mm -1, 2.00mm -1.

βOH=-〔ln(D/C)〕/t. . . Formula 1)

Here, in the above formula (1), t represents the thickness (mm) of the glass used in the measurement of the external transmittance, and C represents the external transmittance ( %), and D represents the external transmittance (%) at a wavelength of 2900 nm when light is incident on the glass parallel to its thickness direction. In addition, ln is the natural logarithm. The unit of βOH is mm ^-1 .

It should be noted that the "external transmittance" refers to the ratio (Iout/Iin) of the intensity (Iout) of the transmitted light through the glass to the intensity (Iin) of the incident light incident on the glass (Iout/Iin), that is, it is also considered The transmittance of the surface reflection on the surface of the glass. The transmittance can be obtained by measuring the transmission spectrum using a spectrophotometer. As the spectroscopic device, "UV-3100 (Shimadzu)" can be used.

The βOH represented by the above formula (1) is defined based on the change in transmittance due to light absorption by the hydroxyl group. Therefore, by evaluating βOH, the concentration of water (and/or hydroxide ion) contained in the glass can be evaluated. That is, βOH is high The glass means that the concentration of water (and/or hydroxide ions) contained in the glass is high.

By setting the value of βOH in the above-mentioned range, the amount of noble metals such as platinum from the melting vessel of the glass that dissolves into the glass can be reduced, and the transmittance after the reduction of the reduced color, that is, after the heat treatment can be improved. Furthermore, the heat treatment time required to reduce the reduced color can be further shortened. On the other hand, if the value of βOH is too large, the devitrification resistance of the glass may decrease, and the amount of volatile matter from the molten glass may increase.

The method of increasing the value of βOH of the glass is not particularly limited, but a method of increasing the amount of water in the molten glass in the melting process is preferably mentioned. As a method of increasing the amount of water in the molten glass, for example, a treatment of adding water vapor to the molten atmosphere, a treatment of bubbling a gas containing water vapor in the molten glass, and the like.

The glass according to this embodiment preferably contains Nb ₂ O ₅ . In the glass according to this embodiment, _{the lower limit of the Nb 2} O ₅ content is preferably 5.0%, and more preferably 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, 10.0%, 10.5%, 11.0%, 11.5%, 12.0%, 12.5%, 13.0%, 13.5%, 14.0%, 14.5%, 15.5%, 16.0%, 16.5%, 17.0%, 17.5% , 18.0%, 18.5%, 19.0%, 19.5%, 20.0%, 20.5%, 21.0%, 21.5%, 22.0%, 22.5%, 23.0%. In addition, _{the upper limit of the content of Nb 2} O ₅ is preferably 60.0%, and more preferably 59.0%, 58.0%, 57.0%, 56.0%, 55.0%, 54.0%, 53.0%, 52.0%, 51.0%, 50.0% in order. , 49.0%, 48.0%, 47.0%, 46.0%, 45.0%, 44.0%, 43.0%, 42.0%, 41.0%, 40.0%, 39.0%, 38.0%, 37.0%.

Nb ₂ O ₅ is a component that contributes to high dispersion. Moreover, it is also a glass component that improves the thermal stability and chemical durability of glass. On the other hand, if _{the content of Nb 2} O ₅ is too large, the thermal stability of the glass decreases and the coloring of the glass tends to increase. Therefore, in the glass according to this embodiment, _{the content of Nb 2} O ₅ is preferably within the above-mentioned range.

In addition, in the glass according to this embodiment, when the content of the glass component is expressed in cationic %, ^{the upper limit of the Nb 5+} content is preferably 30.00 cationic%, and more preferably 29.00 cationic%, 28.50 cationic%, and 28.00 in this order. Cationic%, 27.50 cationic%, 27.00 cationic%, 26.50 cationic%, 26.00 cationic%, 25.50 cationic%, 25.00 cationic%, 24.50 cationic%. The lower limit of the content of Nb ⁵⁺ is preferably 10.00 cationic%, and more preferably 11.00 cationic%, 12.50 cationic%, 12.50 cationic%, 13.00 cationic%, 13.50 cationic%, 14.00 cationic%, 14.50 cationic%, 15.00 cationic% in order. , 15.50 cationic%, 16.00 cationic%, 16.50 cationic%, 17.00 cationic%, 17.50 cationic%.

Nb ⁵⁺ is a component that contributes to high dispersion. Moreover, it is also a glass component that improves the thermal stability and chemical durability of glass. On the other hand, if ^{the content of Nb 5+} is too large, the thermal stability of the glass decreases and the coloring of the glass tends to increase. Therefore, in the glass according to this embodiment, ^{the content of Nb 5+} is preferably within the above-mentioned range.

The glass according to this embodiment preferably contains TiO ₂ . In the glass according to this embodiment, _{the lower limit of the content of TiO 2} is preferably 5.0%, and more preferably 6.0%, 7.0%, 8.0%, 9.0%, 10.0%, 11.0%, 12.0%, and 13.0% in order. , 14.0%, 15.0%, 16.0%, 17.0%, 18.0%, 19.0%. In addition, _{the upper limit of the content of TiO 2} is preferably 50.0%, and more preferably 49.0%, 48.0%, 47.0%, 46.0%, 45.0%, 44.0%, 43.0%, 42.0%, 41.0%, 40.0%, 39.0. %, 38.0%, 37.0%, 36.0%, 35.0%, 34.0%, 33.0%, 32.0%, 31.0%.

TiO ₂ and Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ also greatly contribute to high dispersion. On the other hand, TiO ₂ is easier to increase the coloration of glass. Therefore, in the glass according to this embodiment, _{the content of TiO 2} is preferably within the above-mentioned range.

In addition, in the glass according to the present embodiment, when the content of the glass component is expressed in cationic %, ^{the upper limit of the content of Ti 4+} is preferably 40.00 cationic %, and more preferably 39.00 cationic %, 38.00 cationic %, and 37.50 in this order. Cation %, 37.00 Cation %, 36.50 Cation %, 36.00 Cation %, 35.50 Cation %, 35.00 Cation %, 34.50 Cation %. The lower limit of the content of Ti ⁴⁺ is preferably 20.00 cationic%, and more preferably 21.00 cationic%, 21.50 cationic%, 22.00 cationic%, 22.50 cationic%, 23.00 cationic%, 23.50 cationic%, 24.00 cationic%, 24.50 cationic% in order. , 25.00 cationic %.

Ti ⁴⁺ and Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ also greatly contribute to high dispersion. On the other hand, Ti ⁴⁺ is easier to increase the coloration of the glass. Therefore, in the glass according to this embodiment, ^{the content of Ti 4+} is preferably within the above-mentioned range.

In the glass according to the present embodiment, the lower limit of the mass ratio [TiO ₂ /Nb ₂ O _{5 ] of the content of TiO 2 to} the content of Nb ₂ O ₅ is preferably 0.16, and more preferably 0.17, 0.18, 0.19. , 0.20, 0.23. In addition, the upper limit of the mass ratio [TiO ₂ /Nb ₂ O ₅ ] is preferably 4.50, and more preferably 4.40, 4.30, 4.20, 4.10, 4.00, 3.80, 3.60 in order.

TiO ₂ tends to reduce the solubility of glass and increase the liquidus temperature. On the other hand, Nb ₂ O ₅ suppresses the decrease in liquidus temperature and the increase in refractive index, and contributes to high dispersion. Therefore, by _{containing Nb 2} O ₅ at a certain ratio with respect to TiO ₂ , it is possible to suppress a decrease in the solubility of the glass and an increase in the liquidus temperature. Therefore, in the glass according to this embodiment, the cation ratio [TiO ₂ /Nb ₂ O ₅ ] is preferably set to the above range.

In addition, in the glass according to the present embodiment, when the content of the glass component is expressed in cation %, the upper limit of the cation ratio [Ti ⁴⁺ /Nb ^{5+ ] of the content of Ti 4+ to} the content of Nb ^{5+ is preferably} 6.00, more preferably 5.90, 5.80, 5.70, 5.65, 5.60 in order. The lower limit of the cation ratio [Ti ⁴⁺ /Nb ⁵⁺ ] is preferably 0.40, and more preferably 0.41 and 0.42 in order.

Ti ⁴⁺ tends to decrease the solubility of glass and increase the liquidus temperature. On the other hand, Nb ⁵⁺ suppresses the decrease in liquidus temperature and the increase in refractive index, and contributes to high dispersion. Therefore, Nb ⁵⁺ is contained in a certain ratio with respect to Ti ⁴⁺ , and it is possible to suppress a decrease in the solubility of the glass and an increase in the liquidus temperature. Therefore, in the glass according to the present embodiment, the cation ratio [Ti ⁴⁺ /Nb ⁵⁺ ] is preferably set in the above-mentioned range.

The glass according to this embodiment _{can contain B 2} O ₃ , SiO ₂ , and Al ₂ O _{3 as} a network forming component of glasses other than _{P 2} O ₅ .

In the glass according to this embodiment, _{the upper limit of the content of B 2} O ₃ is preferably 8.0%, and more preferably 7.0%, 6.0%, 5.0%, 4.0%, 3.0%, 2.0%, 1.0% in order. The content of B ₂ O ₃ may be 0%.

B ₂ O ₃ is a network-forming component of glass, and has the effect of improving the meltability of glass. On the other hand, if _{the content of B 2} O ₃ is large, the decrease in Abbe number is suppressed, high dispersion is prevented, and the chemical durability tends to decrease. Therefore, from the viewpoint of improving the thermal stability, meltability, and moldability of the glass, the upper limit of the content of _{B 2} O _{3 is preferably the above range.}

In the glass according to this embodiment, _{the upper limit of the content of SiO 2} is preferably 8.0%, and more preferably 7.0%, 6.0%, 5.0%, 4.0%, 3.5%, 3.0%, 2.5%, 2.0%. , 1.5%, 1.0%. The content of SiO ₂ may be 0%.

SiO ₂ is a network forming component of glass, which has the functions of improving the thermal stability, chemical durability and weather resistance of glass, increasing the viscosity of molten glass, and facilitating molding of molten glass. On the other hand, if _{the content of SiO 2} is large, the meltability of the glass decreases, and the glass raw material tends to remain molten. Therefore, from the viewpoint of improving the meltability of the glass, _{the upper limit of the content of SiO 2} is preferably within the above-mentioned range.

In the glass according to this embodiment, _{the upper limit of the content of Al 2} O ₃ is preferably 5.0%, and more preferably 4.0%, 3.5%, 3.0%, 2.5%, 2.0%, 1.5%, 1.0%, 0.5%. The content of Al ₂ O ₃ may be 0%.

Al ₂ O ₃ is a glass component that has the effect of improving the chemical durability and weather resistance of glass, and can be considered as a network forming component. On the other hand, when _{the content of Al 2} O ₃ increases, the thermal stability of the glass decreases, the glass transition temperature (Tg) increases, and the meltability tends to decrease. Therefore, _{the upper limit of the content of Al 2} O ₃ is preferably within the above-mentioned range.

In the glass according to this embodiment, the total content _{of P 2} O ₅ , B ₂ O ₃ , SiO ₂ and Al ₂ O _{3 as the network forming components of the glass [P 2} O ₅ +B ₂ O ₃ +SiO ₂ +Al ₂ O ₃ ] is preferably 45.0%, and more preferably 44.0%, 43.0%, 42.0%, 41.0%, 40.0%, 39.0%, 38.0%, 37.0%, 36.0%, 35.0%, 34.0. %, 33.0%, 32.0%, 31.0%, 30.0%. In addition, the lower limit of the total content [P ₂ O ₅ +B ₂ O ₃ +SiO ₂ +Al ₂ O ₃ ] is preferably 10.0%, and more preferably 11.0%, 12.0%, 13.0%, 14.0%, and 15.0% in order. , 16.0%, 17.0%, 18.0%, 19.0%, 20.0%.

By setting the total content [P ₂ O ₅ +B ₂ O ₃ +SiO ₂ +Al ₂ O ₃ ] in the above range, the thermal stability of the glass can be improved and the devitrification of the glass can be suppressed.

Further, in the glass of the present embodiment is directed to the, P ₂ O ₅ content relative to the _{P 2 O 5, B 2 O} 3, the quality of the total content of SiO ₂ and Al ₂ O ₃ ratio of [P ₂ O ₅ / ( The lower limit of P ₂ O ₅ +B ₂ O ₃ +SiO ₂ +Al ₂ O ₃ )] is preferably 0.55, and more preferably 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95 in order. It is also possible to set the mass ratio [P ₂ O ₅ /(P ₂ O ₅ +B ₂ O ₃ +SiO ₂ +Al ₂ O ₃ )] to 1.00.

If the mass ratio [P ₂ O ₅ /(P ₂ O ₅ +B ₂ O ₃ +SiO ₂ +Al ₂ O ₃ )] is small, the thermal stability of the glass decreases, and the meltability also decreases. Therefore, from the viewpoint of maintaining high dispersion and good melting properties of the glass, the lower limit of the _{mass ratio [P 2} O ₅ /(P ₂ O ₅ +B ₂ O ₃ +SiO ₂ +Al ₂ O _{3 )] is better} For the above range.

In the glass according to this embodiment, the upper limit of the mass ratio [TiO ₂ /P ₂ O _{5 ] of the content of TiO 2 to} the content of P ₂ O ₅ is preferably 4.50, and more preferably 4.00, 3.50, 3.00 in order. , 2.50, 2.00, 1.50. In addition, the lower limit of the mass ratio [TiO ₂ /P ₂ O ₅ ] is preferably 0.04, and more preferably 0.08, 0.12, 0.16, 0.20, 0.24, 0.28, 0.32, 0.36, 0.40, 0.44, 0.48, 0.52 in order.

In the glass according to the present embodiment, TiO _{2 is} contained, so there is a problem of promoting crystal formation in the glass and lowering the transparency of the glass (white turbidity). _{This problem can be eliminated by containing P 2} O ₅ as a network forming component with respect to TiO ₂ in a ratio within the above-mentioned range.

In addition, in the glass according to the present embodiment, when the content of the glass component is expressed in cation %, the upper limit of the cation ratio [Ti ⁴⁺ /P ^{5+ ] of the content of Ti 4+ to} the content of P ^{5+ is preferably} 1.50, more preferably 1.40, 1.30, 1.29, 1.28, 1.27, 1.26, 1.25, 1.24, 1.23, 1.22 in order. The lower limit of the cation ratio [Ti ⁴⁺ /P ⁵⁺ ] is preferably 0.50, and more preferably 0.51, 0.52, 0.53 in order.

In the glass according to the present embodiment, Ti ^{4+ is} contained, so there is a problem of promoting the formation of crystals in the glass and lowering the transparency of the glass (white turbidity). ^{This problem can be eliminated by containing P 5+} as a network forming component with respect to Ti ⁴⁺ in a ratio within the above-mentioned range.

In the glass according to this embodiment, _{the upper limit of the WO 3} content is preferably 50.0%, and more preferably 49.0%, 48.0%, 47.0%, 46.0%, 45.0%, 44.0%, 43.0%, 42.0% in order , 41.0%, 40.0%, 39.0%, 38.0%, 37.0%, 36.0%, 35.0%, 34.0%, 33.0%, 32.0%, 31.0%, 30.0%. In addition, _{the lower limit of the content of WO 3} is preferably 0.01%, and more preferably 0.1%, 0.3%, 0.5%, 0.7%, and 1.0% in this order. The content of WO ₃ can be 0%.

Although WO ₃ greatly contributes to high dispersion, compared with TiO ₂ , Nb ₂ O _5, and Bi ₂ O ₃ , it tends to cause the coloring of glass and deteriorate the transmittance. Therefore, _{the content of WO 3} is preferably set to the above-mentioned range.

In addition, in the glass according to the present embodiment, when the content of the glass component is expressed in cationic %, ^{the upper limit of the content of W 6+} is preferably 20.00 cationic%, and more preferably 19.00 cationic%, 18.50 cationic%, and 18.00 in this order. Cationic%, 17.50 cationic%, 17.00 cationic%, 16.50 cationic%, 16.00 cationic%, 15.50 cationic%, 15.00 cationic%, 14.50 cationic%, 14.00 cationic%, 13.50 cationic%. The lower limit of the content of W ⁶⁺ is preferably 0.40 cationic %, and more preferably 0.20 cationic% and 0.10 cationic% in order. The content of W ⁶⁺ can be 0 cationic %.

Although W ⁶⁺ greatly contributes to high dispersion, compared to Ti ⁴⁺ , Nb ^5+, and Bi ³⁺ , it tends to cause the coloring of glass and deteriorate the transmittance. Therefore, ^{the content of W 6+} is preferably set to the aforementioned range.

In the glass according to this embodiment, the lower limit of the mass ratio of the total content of _{TiO 2} and WO _{3 to the content of Nb 2} O _{5 [(TiO 2} +WO ₃ )/Nb ₂ O ₅ ] is preferably 0.15, and further More preferably 0.17, 0.19, 0.20, 0.21, 0.23, 0.25, 0.26, 0.28, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0.64, 0.65 . In addition, the upper limit of the mass ratio [(TiO ₂ +WO ₃ )/Nb ₂ O ₅ ] is preferably 8.00, and more preferably 7.90, 7.80, 7.70, 7.60, 7.40, 7.20, and 7.00 in order.

By setting the value of the mass ratio [(TiO ₂ +WO ₃ )/Nb ₂ O ₅ ] to the above range, it is possible to obtain a glass with high dispersion properties suitable for correction of chromatic aberration while suppressing the increase in refractive index.

In addition, in the glass according to the present embodiment, when the content of the glass component is expressed in cation %, the cation ratio of the total content of ^{Ti 4+} and W ^{6+ to the content of Nb 5+ [(Ti 4+} +W ⁶⁺ The upper limit of )/Nb ⁵⁺ ] is preferably 7.70, and more preferably 7.60, 7.50, 7.40, 7.35, 7.30, 7.28, and 7.26 in this order. The lower limit of the cation ratio [(Ti ⁴⁺ +W ⁶⁺ )/Nb ⁵⁺ ] is preferably 0.40, and more preferably 0.41 and 0.42 in order.

By setting the value of the cation ratio [(Ti ⁴⁺ +W ⁶⁺ )/Nb ⁵⁺ ] to the above range, it is possible to obtain a glass with high dispersion properties suitable for chromatic aberration correction while suppressing the increase in refractive index .

In the glass according to this embodiment, _{the upper limit of the Na 2} O content is preferably 10.0%, and more preferably 9.0%, 8.0%, 7.0%, 6.0%, 5.0%, 4.0%, and 3.0% in this order. The content of Na ₂ O may be 0%.

In addition, in the optical glass according to the present embodiment, when the content of the glass component is expressed in cationic %, ^{the upper limit of the Na +} content is preferably 13.00 cationic%, and more preferably 12.00 cationic%, 11.50 cationic%, and 11.00 in this order. Cationic%, 10.50 cationic%, 10.00 cationic%, 9.50 cationic%, 9.00 cationic%, 8.50 cationic%, 8.00 cationic%. The lower limit of the Na ⁺ content is preferably 1.50 cationic %, and more preferably 1.30 cationic %, 1.00 cationic %, 0.70 cationic %, 0.50 cationic %, and 0.30 cationic% in order. The content of Na ⁺ can be 0 cationic %.

In the glass according to this embodiment, _{the upper limit of the K 2} O content is preferably 15.0%, and more preferably 14.0%, 13.0%, 12.0%, 11.0%, 10.0%, 9.0%, 8.0%, 7.0 %, 6.0%, 5.0%. In addition, _{the lower limit of the K 2} O content is preferably 0.01%, and more preferably 0.1%, 0.3%, and 0.4% in this order. The content of K ₂ O may be 0%.

In addition, in the optical glass according to the present embodiment, when the content of the glass component is expressed in cationic %, ^{the upper limit of the K +} content is preferably 15.00 cationic%, and more preferably 14.50 cationic%, 14.00 cationic%, and 13.50 in this order. Cation %, 13.00 Cation %, 12.50 Cation %, 12.00 Cation %, 11.50 Cation %, 11.00 Cation %. The lower limit of the K ⁺ content is preferably 1.00 cationic %, and more preferably 0.70 cationic %, 0.50 cationic %, and 0.30 cationic% in this order. The content of K ⁺ can be 0 cationic %.

Na ₂ O and K ₂ O, or Na ⁺ and K ⁺ have the effect of helping to shorten the heat treatment time required to reduce the reduced color caused by the high-dispersion component. Among Na ₂ O and K ₂ O, Na ₂ O has a high effect, and among Na ⁺ and K ⁺ , Na ^{+ has} a high effect. In addition, the greater the content of these, the greater the effect, but if the content is too large, the thermal stability, chemical durability, and weather resistance of the glass will decrease. Therefore, _{the respective contents of Na 2} O and K ₂ O, Na ⁺ and K ⁺ are preferably set to the aforementioned ranges.

In the glass according to this embodiment, the upper limit of the total content of _{Li 2} O, Na ₂ O, and K _{2 O [Li 2} O+Na ₂ O+K ₂ O] is preferably 20.0%, and more preferably sequentially 19.0%, 18.0%, 17.0%, 16.0%, 15.0%, 14.0%, 13.0%, 12.0%, 11.0%, 10.0%, 9.0%, 8.0%, 7.0%, 6.0%. In addition, the lower limit of the total content [Li ₂ O+Na ₂ O+K ₂ O] is preferably 0.01%, and more preferably 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08% in order. , 0.09%, 0.10%, 0.20%, 0.30%, 0.40%, 0.50%.

Li ₂ O, Na ₂ O, and K ₂ O have the effects of shortening the heat treatment time required to reduce the reduced color caused by the high-dispersion component and improving the meltability of the glass. However, when their content increases, the thermal stability, chemical durability, and weather resistance of the glass will decrease. Therefore, the total content of _{Li 2} O, Na ₂ O, and K _{2 O [Li 2} O+Na ₂ O+K ₂ O] is preferably within the above-mentioned range.

In addition, in the optical glass according to this embodiment, when the content of the glass component is expressed in cationic %, the upper limit of the total content of ^{Li +} , Na ⁺ and K ^{+ [Li +} +Na ⁺ +K ⁺ ] is preferably 22.00 Cationic %, and more preferably 21.00 cationic%, 20.00 cationic%, 19.00 cationic%, 18.00 cationic%, 17.00 cationic%, 16.50 cationic%, 16.00 cationic%, 15.50 cationic%, 15.00 cationic%, 14.50 cationic%, 14.00 cationic% %, 13.50 cationic%, 13.00 cationic%, 12.50 cationic%, 12.00 cationic%, 11.50 cationic%. The lower limit of the total content [Li ⁺ +Na ⁺ +K ⁺ ] is preferably 1.00 cationic%, and more preferably 0.70 cationic%, 0.50 cationic%, and 0.30 cationic% in this order. The total content [Li ⁺ +Na ⁺ +K ⁺ ] can be 0 cationic %.

Li ⁺ , Na ^+, and K ⁺ have the effects of shortening the heat treatment time required to reduce the reduced color caused by high-dispersion components and improving the meltability of the glass. However, when their content increases, the thermal stability, chemical durability, and weather resistance of the glass will decrease. Therefore, the total content of ^{Li +} , Na ⁺ and K ^{+ [Li +} +Na ⁺ +K ⁺ ] is preferably within the above range.

In the glass of the present embodiment is related to the mass content of Li ₂ O and Li ₂ O, Na ₂ O, and the total content of K ₂ O ratio of _{[Li 2 O / (Li 2 O} + Na 2 O + K 2 O )] is preferably 0.0012, and more preferably 0.0013, 0.0014, 0.0015, 0.0016, 0.0017, 0.0018, 0.0019, 0.0020, 0.0021, 0.0022, 0.0023, 0.0024, 0.0025, 0.0026, 0.0027, 0.0028, 0.0029, 0.0030, 0.0032, 0.0035, 0.0037, 0.0040. The upper limit of the mass ratio [Li ₂ O/(Li ₂ O+Na ₂ O+K ₂ O)] is preferably 1.00, and more preferably 0.80, 0.60, 0.50, 0.40, 0.30, 0.20, 0.18, 0.16 in order.

In the glass according to this embodiment, _{the upper limit of the content of Rb 2} O is preferably 5.0%, and more preferably 4.0%, 3.0%, 2.0%, 1.0%, 0.7%, 0.5%, 0.3%, 0.1 %. In addition, the lower limit of the content of _{Rb 2 O is preferably 0%.} The content of Rb ₂ O may be 0%.

In the glass according to this embodiment, _{the upper limit of the content of Cs 2} O is preferably 10.0%, and more preferably 9.0%, 8.0%, 7.0%, 6.0%, 5.0%, 4.5%, 4.0%, 3.5 %, 3.0%. In addition, the lower limit of the content of _{Cs 2 O is preferably 0%.} The content of Cs ₂ O may be 0%.

Rb ₂ O and Cs ₂ O, like Na ₂ O and K ₂ O, have the effect of helping to shorten the heat treatment time required to reduce the reduced color caused by the high-dispersion component, but their effect is smaller than that of Na ₂ O and K ₂ O. In addition, when their content increases, the thermal stability, chemical durability, and weather resistance of the glass will decrease. Therefore, _{each content of Rb 2} O and Cs ₂ O is preferably set to the aforementioned range.

In the glass according to this embodiment, the upper limit of the content of MgO is preferably 5.0%, and more preferably 4.0%, 3.0%, 2.0%, and 1.0% in this order. In addition, the lower limit of the content of MgO is preferably 0%. The content of MgO may be 0%.

In the glass according to this embodiment, the upper limit of the CaO content is preferably 6.0%, and more preferably 5.0%, 4.0%, 3.0%, 2.0%, and 1.0% in this order. In addition, the lower limit of the content of CaO is preferably 0%. The content of CaO may be 0%.

In the glass according to this embodiment, the upper limit of the SrO content is preferably 7.0%, and more preferably 6.0%, 5.0%, 4.0%, 3.0%, 2.0%, 1.0% in this order. In addition, the lower limit of the content of SrO is preferably 0%. The content of SrO may be 0%.

In the glass according to this embodiment, the upper limit of the content of BaO is preferably 10.0%, and more preferably 9.0%, 8.0%, 7.0%, 6.0%, 5.0%, 4.0%, 3.0%, 2.0%, 1.0%. In addition, the lower limit of the content of BaO is preferably 0%. The content of BaO may be 0%.

MgO, CaO, SrO, BaO all have the thermal stability of glass It is a glass component that has the effect of improving the properties and melting properties. However, when the content of these glass components increases, the high dispersion properties are impaired, and the thermal stability of the glass decreases, and the glass tends to become devitrified. Therefore, the respective contents of these glass components are preferably within the aforementioned ranges.

In addition, in the glass according to the present embodiment, when the content of the glass component is expressed in cationic %, ^{the upper limit of the content of Ba 2+} is preferably 10.00 cationic%, and more preferably 9.00 cationic%, 8.00 cationic%, and 7.00 in this order. Cationic%, 6.00 cationic%, 5.00 cationic%, 4.50 cationic%, 4.00 cationic%, 3.50 cationic%, 3.00 cationic%, 2.50 cationic%, 2.00 cationic%, 1.50 cationic%, 1.00 cationic%, 0.70 cationic%. In addition, the lower limit of the content of ^{Ba 2+ is preferably 0 cationic %.} The content of Ba ²⁺ can be 0 cationic %.

Ba ²⁺ is a glass component that has the effect of improving the thermal stability and meltability of glass. However, when the content of these glass components increases, the high dispersion properties are impaired, and the thermal stability of the glass decreases, and the glass tends to become devitrified. Therefore, the respective contents of these glass components are preferably within the aforementioned ranges.

In the glass according to this embodiment, the upper limit of the total content of MgO, CaO, SrO, and Ba0 [MgO+CaO+SrO+BaO] is relatively high from the viewpoint of maintaining thermal stability without hindering high dispersion. Preferably it is 17.0%, and then more preferably 16.0%, 15.0%, 14.0%, 13.0%, 12.0%, 11.0%, 10.0%, 9.0%, 8.0%, 7.0%, 6.0%, 5.0%, 4.0%, 3.0 %, 2.0%, 1.0%. In addition, the lower limit of the total content [MgO+CaO+SrO+BaO] is preferably 0%. The total content [MgO+CaO+SrO+BaO] can be 0%.

In the glass according to this embodiment, the upper limit of the content of ZnO is preferably 5.0%, and more preferably 4.0%, 3.0%, 2.0%, and 1.0% in this order. In addition, the lower limit of the content of ZnO is preferably 0%. The content of ZnO can be 0%.

ZnO is a glass component that has a function of promoting melting of a glass raw material (that is, a function of improving meltability) when the glass is melted. In addition, ZnO has a stronger effect on improving the thermal stability of glass and lowering the liquidus temperature than other divalent metal components such as alkaline earth metals. Therefore, from the viewpoint of improving the meltability and thermal stability of the glass, the lower limit of the content of ZnO is preferably within the above-mentioned range. In addition, from the viewpoint of suppressing the low dispersion of the glass and the decrease in the glass transition temperature Tg, the upper limit of the content of ZnO is preferably within the above-mentioned range.

In the glass according to this embodiment, _{the upper limit of the content of ZrO 2} is preferably 6.0%, and more preferably 5.0%, 4.0%, 3.0%, and 2.0% in this order. In addition, the lower limit of the content of _{ZrO 2 is preferably 0%.} The content of ZrO ₂ may be 0%.

ZrO ₂ is a glass component that has an effect of improving the thermal stability of glass. However, _{when the content of ZrO 2} is too large, the thermal stability of the glass tends to decrease. In addition, the glass raw material becomes easy to melt and remain. Therefore, the upper limit of the content of _{ZrO 2} is preferably the above-mentioned range from the viewpoint of maintaining the meltability and thermal stability of the glass well and achieving the required optical properties. On the other hand, from the viewpoint of achieving required optical properties and improving the thermal stability of the glass, the lower limit of the content of _{ZrO 2 is preferably the above range.}

In the glass according to this embodiment, _{the upper limit of the content of Ta 2} O ₅ is preferably 9.0%, and more preferably 8.0%, 7.0%, 6.0%, 5.0%, 4.0%, and 3.0% in this order. In addition, the lower limit of the content of _{Ta 2} O _{5 is preferably 0%.} The content of Ta ₂ O ₅ may be 0%.

Ta ₂ O ₅ is a glass component that has an effect of improving the thermal stability of glass. On the other hand, Ta ₂ O ₅ lowers the dispersion of the glass. In addition, Ta ₂ O ₅ is an extremely expensive component compared to other glass components. As the content of Ta ₂ O ₅ increases, the production cost of the glass increases. In addition, Ta ₂ O ₅ has a higher molecular weight than other glass components, and therefore increases the specific gravity of the glass. As a result, the weight of the glass optical element increases. In addition, when _{the content of Ta 2} O ₅ increases, the meltability of the glass is lowered, and melting residue of the glass raw material tends to occur when the glass is melted. Therefore, _{the content of Ta 2} O ₅ is preferably within the above-mentioned range.

In the glass according to this embodiment, _{the upper limit of the Ga 2} O ₃ content is preferably 4.0%, and more preferably 3.5%, 3.0%, 2.5%, 2.0%, 1.5%, 1.0%, 0.5%, 0.1%. In addition, the lower limit of the content of _{Ga 2} O _{3 is preferably 0%.} The content of Ga ₂ O ₃ may be 0%.

In the glass according to this embodiment, _{the upper limit of the content of In 2} O ₃ is preferably 5.0%, and more preferably 4.5%, 4.0%, 3.5%, and 3.0% in this order. In addition, the lower limit of the content of _{In 2} O _{3 is preferably 0%.} The content of In ₂ O ₃ may be 0%.

In the glass according to this embodiment, _{the upper limit of the content of Sc 2} O ₃ is preferably 5.0%, and more preferably 4.0%, 3.0%, 2.0%, and 1.0% in this order. In addition, the lower limit of the content of _{Sc 2} O _{3 is preferably 0%.} The content of Sc ₂ O ₃ may be 0%.

In the glass according to this embodiment, _{the upper limit of the content of HfO 2} is preferably 8.0%, and more preferably 7.0%, 6.5%, 6.0%, 5.5%, 5.0%, 4.5%, 4.0%, 3.5% in order , 3.0%, 2.5%, 2.0%, 1.5%, 1.0%, 0.5%, 0.1%. In addition, the lower limit of the content of _{HfO 2 is preferably 0%.} The content of HfO ₂ may be 0%.

Ga ₂ O ₃ , In ₂ O ₃ , Sc ₂ O ₃ , and HfO ₂ are all expensive components. Therefore, _{the contents of each of Ga 2} O ₃ , In ₂ O ₃ , Sc ₂ O ₃ , and HfO ₂ are preferably within the above-mentioned range.

In the glass according to this embodiment, _{the upper limit of the content of Lu 2} O ₃ is preferably 5.0%, and more preferably 4.5%, 4.0%, 3.5%, and 3.0% in this order. In addition, the lower limit of the content of _{Lu 2} O _{3 is preferably 0%.} The content of Lu ₂ O ₃ may be 0%.

Since Lu ₂ O _{3 has a} large molecular weight, it is also a glass component that increases the specific gravity of glass. Thus, preferred to reduce the content of Lu ₂ O _3, Lu ₂ O ₃ content is preferably in the above range.

In the glass according to this embodiment, _{the upper limit of the content of GeO 2} is preferably 6.0%, and more preferably 5.0%, 4.0%, 3.0%, 2.0%, 1.5%, 1.0%, 0.5%, 0.1% . In addition, the lower limit of the content of _{GeO 2 is preferably 0%.} The content of GeO ₂ may be 0%.

GeO ₂ is a component that stands out as an expensive component among commonly used glass components. Therefore, from the viewpoint of reducing the manufacturing cost of glass, _{the content of GeO 2} is preferably within the above-mentioned range.

In the glass according to this embodiment, _{the upper limit of the content of La 2} O ₃ is preferably 5.0%, and more preferably 4.5%, 4.0%, 3.5%, 3.0%, 2.5%, 2.0%, 1.5%, 1.0%, 0.5%. In addition, the lower limit of the content of _{La 2} O _{3 is preferably 0%.} The content of La ₂ O ₃ may be 0%.

When _{the content of La 2} O ₃ increases, the thermal stability of the glass decreases, and the glass tends to become devitrified during production. Therefore, from the viewpoint of suppressing a decrease in the thermal stability of the glass, _{the content of La 2} O ₃ is preferably within the above-mentioned range.

In the glass according to this embodiment, _{the upper limit of the content of Gd 2} O ₃ is preferably 8.0%, and more preferably 7.0%, 6.0%, 5.0%, 4.0%, 3.0%, 2.0%, 1.5%, 1.0%. In addition, the lower limit of the content of _{Gd 2} O _{3 is preferably 0%.} The content of Gd ₂ O ₃ may be 0%.

When _{the content of Gd 2} O ₃ becomes too large, the thermal stability of the glass decreases, and the glass tends to devitrify during production. In addition, _{when the content of Gd 2} O ₃ becomes too large, the specific gravity of the glass increases, which is not preferable. Therefore, from the viewpoint of maintaining the thermal stability of the glass well and suppressing an increase in specific gravity, _{the content of Gd 2} O ₃ is preferably within the above-mentioned range.

In the glass according to this embodiment, _{the upper limit of the Y 2} O ₃ content is preferably 5.0%, and more preferably 4.5%, 4.0%, 3.5%, 3.0%, 2.5%, 2.0% in order. In addition, the lower limit of the content of _{Y 2} O _{3 is preferably 0%.} The content of Y ₂ O ₃ may be 0%.

When _{the content of Y 2} O ₃ becomes too large, the thermal stability of the glass decreases, and the glass tends to become devitrified during production. Therefore, from the viewpoint of suppressing a decrease in the thermal stability of the glass, _{the content of Y 2} O ₃ is preferably within the above-mentioned range.

In the glass according to this embodiment, _{the upper limit of the content of Yb 2} O ₃ is preferably 5.0%, and more preferably 4.5%, 4.0%, 3.5%, 3.0%, 2.5%, 2.0%, 1.5%, 1.0%, 0.5%, 0.1%. In addition, the lower limit of the content of _{Yb 2} O _{3 is preferably 0%.} The content of Yb ₂ O ₃ may be 0%.

Yb ₂ O ₃ has a _{higher molecular weight than La 2} O ₃ , Gd ₂ O ₃ , and Y ₂ O ₃ , and therefore increases the specific gravity of the glass. When the specific gravity of the glass increases, the quality of the optical element increases. Therefore, it is desirable to _{reduce the content of Yb 2} O ₃ to suppress an increase in the specific gravity of the glass.

In addition, _{when the content of Yb 2} O ₃ is too large, the thermal stability of the glass decreases, and the glass tends to become devitrified during production. From the viewpoints of preventing a decrease in the thermal stability of the glass and suppressing an increase in specific gravity, _{the content of Yb 2} O ₃ is preferably within the above-mentioned range.

The glass involved in this embodiment is preferably mainly composed of the above-mentioned glass components, that is, selected from P ₂ O ₅ , B ₂ O ₃ , SiO ₂ , Al ₂ O ₃ , TiO ₂ , Nb ₂ O ₅ , WO ₃ , Bi ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, Rb ₂ O, Cs ₂ O, MgO, CaO, SrO, BaO, ZnO, ZrO ₂ , Ta ₂ O ₅ , Ga ₂ O ₃ , In ₂ O ₃ , Sc ₂ O ₃ , HfO ₂ , Lu ₂ O ₃ , GeO ₂ , La ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ and Yb ₂ O ₃ , the total content of the above glass components is preferable More than 95%, more preferably more than 98%, still more preferably more than 99%, still more preferably more than 99.5%.

In the glass according to this embodiment, _{the upper limit of the TeO 2} content is preferably 5.0%, and more preferably 4.5%, 4.0%, 3.5%, 3.0%, 2.5%, 2.0%, 1.5%, 1.0%. , 0.5%, 0.1%. In addition, _{the lower limit of the TeO 2} content is preferably 0%. The content of TeO ₂ may be 0%.

Since TeO ₂ is toxic, it is preferable to reduce the content of _{TeO 2.} Therefore, _{the content of TeO 2} is preferably within the above-mentioned range.

In the glass according to this embodiment, the anion component (that is, the anion component) is mainly oxygen ions, and as other anions, halogen ions such as chloride ions, iodide ions, and bromide ions can be contained in a small amount.

Even when a halide is contained as a glass component, it is preferable to keep the content of the halide in a small amount so that the ratio (mass ratio) of the oxide in the total glass component does not become 95% by mass or less.

In addition, in the optical glass according to the present embodiment, the upper limit of the content of halogen ions is preferably 4 anion%, and more preferably 3 anion%, 2 anion%, 1 anion%, and 0.5 anion% in this order. The content of halide ions can be 0 anion%. The term "anion %" is the molar percentage when the total content of all anion components contained in the glass is set to 100%.

That is, in the glass according to this embodiment, all the glass The content of the oxide in the component is preferably more than 95% by mass. Furthermore, the lower limit of the content of oxides in all glass components is more preferably 97% by mass, 99% by mass, 99.5% by mass, 99.9% by mass, 99.95% by mass, and 99.99% by mass in order, and the content of oxides in all glass components It can be 100% by mass. The glass in which the content of oxides in all glass components is 100% by mass does not substantially contain halides.

It should be noted that the glass according to the present embodiment is preferably basically composed of the above-mentioned glass components, but other components may be contained within a range that does not hinder the effects of the present invention. In addition, in the present invention, the inclusion of unavoidable impurities is not excluded.

<Other ingredients composition>

Pb, As, Cd, Tl, Be, and Se are all toxic. Therefore, the glass according to this embodiment preferably does not contain these elements as glass components.

U, Th, and Ra are all radioactive elements. Therefore, the glass according to this embodiment preferably does not contain these elements as glass components.

V, Cr, Mn, Fe, Co, Ni, Cu, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm will increase the color of glass and may become a source of fluorescence. Therefore, it is preferable that the glass concerning this embodiment does not contain these elements as a glass component.

Sb(Sb ₂ O ₃ ), Sn(SnO ₂ ), and Ce(CeO ₂ ) are optionally added elements that function as fining agents. Among them, Sb (Sb ₂ O ₃ ) is a clarifying agent with a large clarifying effect. However, Sb (Sb ₂ O ₃ ) has strong oxidizing properties. If the amount of Sb (Sb ₂ O ₃ ) added is increased, light absorption by Sb ions will increase the coloration of the glass, which is not preferable. In addition, if Sb is present in the melt when the glass is melted, the platinum constituting the glass melting crucible is promoted to dissolve into the melt, and the platinum concentration in the glass increases. If platinum exists as an ion in the glass, the coloration of the glass increases due to the absorption of light. In addition, if platinum is present as a solid substance in the glass, it becomes a scattering source of light and lowers the quality of the glass. Sn(SnO ₂ ) and Ce(CeO ₂ ) have a smaller clarifying effect than Sb(Sb ₂ O _{3 ).} When Sn(SnO ₂ ) and Ce(CeO ₂ ) are added in large amounts, the coloration of the glass will be enhanced. Therefore, when adding a clarifying agent, it is better to pay attention to the addition amount while adding Sb (Sb ₂ O ₃ ).

The content of Sb ₂ O ₃ is expressed in an additive manner. That is, _{the range of the content of Sb 2} O ₃ when the total content of all glass components other than _{Sb 2} O ₃ , SnO ₂ and CeO ₂ is 100% by mass is preferably less than 1% by mass, more preferably less than 0.5 The mass% is more preferably less than 0.1 mass %. The content of Sb ₂ O ₃ may be 0% by mass.

The content of SnO ₂ is also expressed in an additive manner. That is, _{the range of the content of SnO 2} when the total content of all glass components other than _{SnO 2} , Sb ₂ O ₃ and CeO ₂ is 100% by mass is preferably less than 2% by mass, more preferably less than 1% by mass , More preferably less than 0.5% by mass, and still more preferably less than 0.1% by mass. The content of SnO ₂ may be 0% by mass. By setting _{the content of SnO 2} in the above range, the clarity of the glass can be improved.

The content of CeO ₂ is also expressed in an additive manner. That is, _{the range of the CeO 2} content when the total content of all glass components other than _{CeO 2} , Sb ₂ O ₃ , and SnO ₂ is 100% by mass is preferably less than 2% by mass, more preferably less than 1% by mass , More preferably less than 0.5% by mass, and still more preferably less than 0.1% by mass. The content of CeO ₂ may be 0% by mass. By setting _{the content of CeO 2} in the above range, the clarity of the glass can be improved.

(Glass characteristics)

<Glass transition temperature Tg>

The upper limit of the glass transition temperature (Tg) of the glass according to this embodiment is preferably 750°C, and more preferably 740°C, 730°C, 720°C, 710°C, and 700°C in this order. In addition, the lower limit of the glass transition temperature (Tg) is preferably 500°C, and more preferably 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, 600°C. ℃, 610℃, 620℃, 630℃.

When the upper limit of the glass transition temperature (Tg) satisfies the above range, the increase in the heat treatment temperature of the glass can be suppressed, and the annealing equipment such as the continuous annealing furnace called "lehr" and the batch annealing furnace can be reduced. damage. In addition, the power consumption of the furnace can be controlled.

When the lower limit of the glass transition temperature (Tg) satisfies the above range, it is easy to maintain the desired Abbe number, and it is easy to maintain the thermal stability of the glass well.

<refractive index n _d >

In the glass according to this embodiment, _{the upper limit of the refractive index (n d} ) at a wavelength of 587.56 nm is preferably 2.1500, and more preferably 2.1400, 2.1300, 2.1200, 2.1100, 2.1000, 2.0900, 2.0800, 2.0700, 2.0600 , 2.0500, 2.0400. In addition, _{the lower limit of n d} is preferably 1.8800, and in turn, 1.8900, 1.9000, 1.9100, 1.9200, 1.9300, 1.9350, 1.9400, 1.9450, 1.9500, 1.9600, and 1.9700. The larger the value, the better.

<Refractive index n _C >

In the glass according to this embodiment, _{the upper limit of the refractive index n C} at a wavelength of 656.27 nm is preferably 2.1350, and more preferably 2.1250, 2.1150, 2.15050, 2.0950, 2.0850, 2.0750, 2.0650, 2.0550, 2.0450, 2.0350 , 2.0250, 2.0150. In addition, the lower limit of the refractive index is preferably 1.8650, and further successively 1.8750, 1.8850, 1.8950, 1.9050, 1.9150, 1.9200, 1.9250, 1.9350, 1.9400, 1.9450, and 1.9550. The larger the value, the better.

<Light Transmittance of Glass>

In this embodiment, the light transmittance can be evaluated by the degree of coloration (λ5).

A glass (thickness of 10.0 mm±0.1 mm) having two optically polished planes parallel to each other is used, and light is incident perpendicular to the plane from one of the two planes. Then, the ratio (Iout/Iin) of the intensity (Iout) of the transmitted light emitted from another plane to the intensity (Iin) of the incident light (Iout/Iin) is calculated, that is, the external transmittance is calculated. Using a spectrophotometer, the external transmittance is measured while scanning the wavelength of incident light in the range of, for example, 280 to 700 nm, thereby obtaining a spectral transmittance curve.

The external transmittance increases as the wavelength of incident light moves from the absorption end of the glass on the short-wavelength side to the long-wavelength side, and shows a high value.

λ5 is the wavelength at which the external transmittance becomes 5%, and in the wavelength region of 280 to 700 nm, the external transmittance of the glass on the long wavelength side longer than λ5 shows a value greater than 5%.

By using glass whose wavelength is shortened to λ5, it is possible to provide an optical element that can reproduce colors ideally.

For this reason, the upper limit of λ5 is preferably 460 nm, and more preferably 455 nm, 450 nm, 445 nm, 440 nm, 435 nm, 430 nm, 425 nm, and 420 nm in order. The target of the lower limit of λ5 is 360 nm.

<Specific gravity of glass>

The glass according to this embodiment is a high-dispersion glass and has a small specific gravity. Pass Often, as long as the specific gravity of the glass can be reduced, the weight of the lens can be reduced. As a result, it is possible to reduce the power consumption of the autofocus drive of the lens-mounted camera lens. On the other hand, when the specific gravity is excessively reduced, it will cause a decrease in thermal stability. Therefore, the upper limit of the specific gravity (d) is preferably 5.60, and more preferably 5.50, 5.40, 5.30, 5.20, 5.10, 5.00, 4.90, 4.80, 4.70, 4.60, 4.50, 4.40, 4.30, 4.20, 4.10, 4.00, 3.90, 3.80, 3.70. In addition, from the viewpoint of improving thermal stability, the lower limit of the specific gravity (d) is preferably 2.80, and more preferably 2.90, 3.00, 3.10, and 3.20 in this order.

<Liquid line temperature>

The upper limit of the liquidus temperature of the glass according to this embodiment is preferably 1400°C, and more preferably 1390°C, 1380°C, 1370°C, 1360°C, 1350°C, 1340°C, 1330°C, 1320°C, 1310 ℃, 1300℃. In addition, the lower limit of the liquidus temperature is preferably 1000°C, and more preferably 1010°C, 1020°C, 1030°C, 1040°C, 1050°C, 1060°C, 1070°C, 1080°C, 1090°C, 1100°C, 1110 ℃, 1120℃, 1130℃, 1140℃, 1150℃, 1160℃, 1170℃, 1180℃. According to the glass according to this embodiment, a high dispersion glass with improved thermal stability of the glass can be obtained.

It should be noted that the liquidus temperature is determined in the following manner. Put 10cc (10ml) of glass into a platinum crucible, melt it at 1250℃~1350℃ for 20-30 minutes, then cool to below the glass transition temperature (Tg), and put the glass together with the platinum crucible into a predetermined temperature for melting Keep in the furnace for 2 hours. The holding temperature is set to 1000°C or higher with 5°C or 10°C as a scale, and after holding for 2 hours, it is cooled, and the presence or absence of crystals inside the glass is observed with an optical microscope of 100 times. The lowest temperature for precipitation without crystals was defined as the liquidus temperature.

(Production of glass)

The glass according to the embodiment of the present invention may be prepared by blending glass raw materials so as to have the aforementioned predetermined composition and using the blended glass raw materials in accordance with a known glass manufacturing method. For example, a plurality of compounds are blended and thoroughly mixed to form a batch raw material, and the batch raw material is put into a melting vessel to be melted, clarified, and homogenized, and then the molten glass is molded and slowly cooled to obtain glass. Or put the batch raw materials into a melting vessel for rough melt. The melt obtained by rough melting is quenched and pulverized to produce glass cullet. Furthermore, the cullet is put into a melting vessel, heated and remelt (remelt) to prepare a molten glass, and after clarification and homogenization, the molten glass is molded and slowly cooled to obtain glass. The molding and slow cooling of molten glass may be performed by applying a known method.

In the production of the glass according to the present embodiment, when batch raw materials are rough melted to produce cullet, the lower limit of the melting temperature at the time of rough melting is preferably 1000°C, and more preferably successively 1050°C, 1100°C, 1150°C, 1200°C, 1250°C, 1300°C. In addition, the upper limit of the melting temperature is preferably 1500°C, and more preferably 1450°C, 1400°C, and 1350°C in this order.

When the above-mentioned cullet is melted, clarified, and molded to produce the glass according to this embodiment, the lower limit of the melting temperature of the cullet is preferably 1000°C, and more preferably 1050°C, 1100°C, 1150°C, 1200°C, 1250°C, 1300°C. In addition, the upper limit of the melting temperature is preferably 1500°C, and more preferably 1450°C, 1400°C, and 1350°C in this order.

When the batch raw materials are melted, clarified, and molded without going through the cullet process to manufacture the glass involved in this embodiment, the batch raw materials The lower limit of the melting temperature is preferably 1000°C, and more preferably 1050°C, 1100°C, 1150°C, 1200°C, 1250°C, and 1300°C in this order. In addition, the upper limit of the melting temperature is preferably 1500°C, and more preferably 1450°C, 1400°C, and 1350°C in this order.

In the production of the glass according to this embodiment, the lower limit of the clarification temperature when clarifying the molten glass is preferably 1000°C, and more preferably 1050°C, 1100°C, 1150°C, 1200°C, 1250°C, and 1300°C. ℃. In addition, the upper limit of the clarification temperature is preferably 1500°C, and more preferably 1450°C, 1400°C, and 1350°C in this order.

In the production of the glass according to this embodiment, the lower limit of the outflow temperature when the molten glass flows out of the forming mold is preferably 1000°C, and more preferably 1050°C, 1100°C, 1150°C, 1200°C, 1250°C, 1300°C. In addition, the upper limit of the outflow temperature is preferably 1500°C, and more preferably 1450°C, 1400°C, and 1350°C in this order.

It should be noted that as long as the desired glass component can be introduced into the glass at the desired content, the compound used when preparing the batch material is not particularly limited. Examples of such compounds include oxides, Phosphoric acid, metaphosphate, phosphorus pentoxide, carbonate, nitrate, hydroxide, fluoride, etc.

(Manufacturing of optical glass)

As the optical glass according to the embodiment of the present invention, the glass according to the embodiment of the present invention can be used as it is.

In the case where the glass according to the embodiment of the present invention exhibits a reduced color, the glass according to the embodiment can be heat-treated to reduce the color Lower it to make optical glass. As a method of heat treatment, a known method can be used. For example, a method of heating the glass to a temperature lower than the glass transition temperature (Tg) by 5 to 20°C and holding it until the coloring is sufficiently reduced. It should be noted that the stress of the glass can be removed by performing a slow cooling treatment after the heat treatment. As a method of slow cooling, a well-known method can be used. For example, a method of gradually lowering the temperature to a temperature lower than the heating temperature of the above-mentioned heat treatment by 100 to 150°C can be mentioned.

(Manufacturing of glass materials for polishing and glass materials for press molding)

The glass material for polishing and the glass material for press molding according to the embodiment of the present invention can be manufactured from any of the glass and optical glass according to the embodiment.

The glass material for polishing can be manufactured as follows: the glass or optical glass is subdivided to produce pieces, and each piece is rough polished (barrel polishing) as necessary to equalize the weight and make the release agent easy to adhere to the surface, Reheating is performed to press the softened glass into the desired shape. Alternatively, during the manufacturing process of glass or optical glass, a predetermined weight of molten glass is separated on a mold and directly press-molded to manufacture.

The glass material for press molding can be manufactured by subdividing glass or optical glass into a predetermined volume, grinding and polishing the surface. Alternatively, the molten glass may be dropped during the manufacturing process of glass or optical glass, and the molten glass may be formed by drop molding.

In the manufacture of glass materials for polishing and glass materials for press molding, heat treatment for reducing the reduced color may also be performed. The method of heat treatment is the same as the method of heat treatment in the production of the above-mentioned optical glass. The heat treatment can be performed at any stage after molding, or before or after grinding and polishing.

(Manufacturing of optical components, etc.)

The optical element according to the embodiment of the present invention can be manufactured from any of the glass according to the embodiment of the present invention, optical glass, glass material for polishing, and glass material for press molding.

The optical element according to the embodiment of the present invention can be manufactured by subdividing glass or optical glass into a predetermined volume, and grinding and polishing the surface. In addition, it can also be manufactured as follows: the glass or optical glass is subdivided to produce pieces, and each piece is rough polished (barrel polishing) as necessary to equalize the weight and make the release agent easy to adhere to the surface. After reheating, the softened glass is pressed into a shape similar to the shape of the desired optical element, and finally grinding and polishing are performed. Alternatively, during the manufacturing process of glass or optical glass, the molten glass of a predetermined weight is separated on the forming mold and directly press-molded, and finally it is manufactured by grinding and polishing.

The optical element according to the embodiment of the present invention can be manufactured by grinding and polishing the above-mentioned polishing glass material. In addition, the optical element according to the embodiment of the present invention can be manufactured by precisely pressing the glass material for press molding described above. The glass material for press molding can also be manufactured by precision pressing after heating.

In the manufacture of the optical element according to the embodiment of the present invention, heat treatment for reducing the reduced color can be performed. The method of heat treatment is the same as the method of heat treatment in the production of the above-mentioned optical glass. The heat treatment can be performed after press molding or precision pressing, and it can also be performed at any stage before or after grinding and polishing.

In addition, in the optical element according to the embodiment of the present invention, During manufacturing, centering and edging can also be performed as needed.

The optically functional surface of the manufactured optical element can be coated with an anti-reflection film, a total reflection film, etc. according to the purpose of use.

As the optical element, various lenses such as aspheric lenses, microlenses, and lens arrays, diffraction gratings, and the like can be exemplified.

Second embodiment

The glass of the second embodiment of the present invention is a phosphate glass containing an Abbe number (v _d ) of 18.10 or less and containing at least one oxide _{selected from the group consisting of TiO 2} , Nb ₂ O ₅ , WO ₃ and Bi ₂ O _3.

It will be melted for another 90 minutes at a temperature higher than the liquidus temperature (LT) 110~120℃ in an atmospheric atmosphere and molded, and in an atmospheric atmosphere at a holding temperature 0~20℃ lower than the glass transition temperature (Tg) Hold for 15 minutes and slowly cool to a temperature 120°C lower than the above holding temperature at a cooling rate of 30°C/h. The glass is processed into a glass with a length of 17mm, a width of 13mm, and a thickness of 10mm; when viewed from above, it is at one end from the longitudinal direction The part in the range of 0~5mm and the distance of 0~5mm from the horizontal end is set as the glass end, which is 6~11mm from the vertical end and 4~9mm from the horizontal end when viewed from above. In the case where the part of the distance range is set as the center of the glass; heat treatment in an atmospheric atmosphere at a heating rate of 100°C/h and maintained at a heat treatment temperature 5 to 15°C lower than the glass transition temperature Tg and 30 ℃/h cooling rate slow cooling to a temperature 120 ℃ lower than the above heat treatment temperature slow cooling treatment is performed once or repeated multiple times until the light is incident parallel to the thickness direction when the wavelength is 656 nm, the outside of the glass end is transmitted The external transmittance (T _A ) and the external transmittance (T _{B ) of the central part of the glass are more than the value (T 1} ) calculated by the following formula (2) and the external transmittance (T _A ) of the end of the glass is the same as that of the glass The difference (T _A- T _B ) of the external transmittance (T _B ) of the center portion is 5% or less. In this case, the total time during the heat treatment at the heat treatment temperature is within 48 hours.

T ₁ =0.83×{1-{(n _C -1)/(n _C +1)} ² } ² ×98. . . Formula (2)

[In formula (2), n _C is the difference (T _A -T _B ) _{between the external transmittance (T A} ) of the end of the glass and the external transmittance (T _B ) of the center of the glass after the heat treatment and slow cooling treatment are performed. The refractive index at a wavelength of 656.27 nm when it is 5% or less. ]

Hereinafter, the glass according to the second embodiment will be described in detail.

In the glass according to the second embodiment, the Abbe number (ν _d ) is 18.10 or less. The upper limit of the Abbe number (ν _d ) is preferably 18.05, and more preferably 18.00, 17.90, 17.80, 17.70, 17.60, 17.50, 17.40, 17.30, 17.20, 17.10, 17.00, 16.90, 16.80, 16.78, 16.76, 16.74 in order. , 16.72, 16.70, 16.68, 16.66, 16.64, 16.62, 16.60, 16.58, 16.56, 16.54, 16.52, 16.50. In addition, the lower limit of the Abbe number is preferably 15.00, and more preferably 15.10, 15.20, 15.25, 15.30, 15.35, 15.40, 15.45, 15.50, 15.52, 15.54, 15.56, 15.58, and 15.60 in this order.

The glass according to the second embodiment contains at least one oxide _{selected from TiO 2} , Nb ₂ O ₅ , WO ₃ and Bi ₂ O _3.

The glass according to the second embodiment is phosphate glass. Therefore, the glass according to the second embodiment mainly contains phosphate as a network forming component, and the content thereof is expressed _{as the content of P 2} O _5.

In the glass according to the second embodiment, _{the lower limit of the content of P 2} O ₅ is preferably 7.0%, and more preferably 8.0%, 9.0%, 10.0%, 11.0%, 12.0%, 13.0%, and 14.0% in order. , 15.0%, 16.0%, 17.0%, 18.0%, 19.0%, 20.0%. In addition, _{the upper limit of the content of P 2} O ₅ is preferably 37.0%, and more preferably 36.0%, 35.0%, 34.5%, 34.0%, 33.5%, 33.0%, 32.5%, 32.0%, 31.5%, 31.0% in order. , 30.5%, 30.0%.

P ₂ O ₅ is a component necessary for the glass to contain a large amount of high-dispersion components. On the other hand, if P ₂ O ₅ is contained excessively, the meltability will deteriorate. Therefore, in the glass according to this embodiment, it is preferable to _{set the content of P 2} O ₅ in the above-mentioned range.

In addition, in the glass according to the second embodiment, when the content of the glass component is expressed in cationic %, ^{the upper limit of the content of P 5+} is preferably 42.00 cationic%, and more preferably 41.50 cationic%, 41.00 cationic%, 40.50 cationic%, 40.00 cationic%, 39.50 cationic%, 39.00 cationic%, 38.50 cationic%, 38.00 cationic%, 37.50 cationic%, 37.00 cationic%, 36.50 cationic%, 36.00 cationic%. The lower limit of the content of P ⁵⁺ is preferably 25.00 cationic%, and more preferably 25.50 cationic%, 26.00 cationic%, 26.50 cationic%, 27.00 cationic%, 27.50 cationic%, 28.00 cationic%, 28.50 cationic%, 29.00 cationic% in order. , 29.30 positive ion%.

P ⁵⁺ is a component necessary to suppress the increase in refractive index n _d and to contain a large amount of high-dispersion components in the glass. On the other hand, if P ⁵⁺ is contained excessively, the solubility will deteriorate. Therefore, in the optical glass according to this embodiment, it is preferable to ^{set the content of P 5+} in the above-mentioned range.

The glass according to the second embodiment can relatively uniformly reduce the reduced _{color caused by high dispersion components such as TiO 2} , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ , and can shorten the heat treatment time required to reduce the reduced color. Glass. Specifically, the retention time at the heat treatment temperature (hereinafter sometimes referred to as "fading time") at the heat treatment temperature that can reduce the reduced color to a level where there is no problem when the glass is heat-treated by a predetermined operation is within 48 hours Glass. The details are as follows.

In the heat treatment for reducing the reduced color, the fading time until the transmittance of the glass reaches a predetermined range varies depending on the coloring state of the glass and the size of the glass.

Therefore, in the second embodiment, the fading time is evaluated using a reduced glass sample obtained by reducing the glass according to the present embodiment under certain conditions, performing coloring, and processing to a predetermined size. The reduced glass sample used in the measurement was obtained as follows: the glass according to the present embodiment was re-melted for 90 minutes at a temperature higher than the liquidus temperature (LT) at a temperature of 110 to 120°C than the liquidus temperature (LT) for 90 minutes and then molded. The glass processing is obtained by holding the glass transition temperature (Tg) lower than the glass transition temperature (Tg) at a holding temperature of 0-20°C for 15 minutes, and slowly cooling at a temperature drop rate of 30°C/h to a temperature 120°C lower than the above holding temperature in an atmospheric atmosphere. It is 17mm long, 13mm wide, and 10mm thick.

For remelting the glass at a temperature higher than the liquidus temperature (LT) by 110~120℃ in an atmospheric atmosphere, just put the glass in a platinum crucible, heat it, and remelt it to make molten glass. . At this time, coloration caused by high-dispersion components occurs.

The molten glass is poured into a mold and formed into a plate shape. Keep it at a holding temperature of 0-20℃ lower than the glass transition temperature (Tg) for 15 minutes in an atmospheric atmosphere, and slowly cool it to a temperature 120℃ lower than the above-mentioned holding temperature at a cooling rate of 30℃/h to remove the glass Stress.

The stress-removed glass is subdivided, polished, and processed into long The size is 17mm, width 13mm, and thickness 10mm. At this time, the upper surface and the lower surface (a surface with a length of 17 mm and a width of 13 mm) were optically polished to obtain a reduced glass sample.

The reduced glass sample obtained in this way was subjected to heat treatment and slow cooling treatment under the following conditions, and the fading time was evaluated.

That is, heat treatment and slow cooling treatment are performed in an air atmosphere, and the heat treatment is performed at a heating rate of 100°C/h and maintained at a heat treatment temperature 5-15°C lower than the glass transition temperature (Tg). The slow cooling treatment is Slowly cool at a temperature drop rate of 30°C/h to a temperature 120°C lower than the above heat treatment temperature. Through the above heat treatment, the coloration caused by high-dispersion components is reduced.

The above heat treatment and slow cooling treatment are performed until the reduced glass sample fades to the extent that there is no practical problem. That is, the above-described heat treatment and slow cooling process until the wavelength of incident light parallel to the thickness direction of the sample after treatment the transmittance of the glass outer end portion (T _A) when the transmittance of 656nm and an outer central portion of the glass (T _{B) It is the value (T 1} ) or more calculated by the following formula (2) and the difference (T _A -T _B ) between the external transmittance (T _A ) at the end of the glass and the external transmittance (T _{B) at the center of the glass is} 5% or less.

T ₁ =0.83×{1-{(n _C -1)/(n _C +1)} ² } ² ×98. . . Formula (2)

Note that (2) n _C above formula is subjected to heat treatment and slow cooling process until the external transmittance (T _A) and the outer end portion of the glass transmittance (T _B) of the center portion of the glass difference (T _A -T _B ) Is the refractive index at a wavelength of 656.27 nm when it is 5% or less. The refractive index (n _C ) is measured based on the standards of the Japan Optical Glass Industry Association (JOGIS 01-2003).

The above heat treatment and slow cooling treatment can be one time, in addition, it can be To carry out multiple times. The fading time in the case of performing the above heat treatment and slow cooling treatment multiple times may be different each time.

In the glass according to the second embodiment, the total discoloration time of the heat treatment is within 48 hours, preferably within 46 hours, and more preferably within 44 hours, within 42 hours, within 40 hours, and within 38 hours in this order , Within 36 hours, within 34 hours, within 32 hours, within 30 hours, within 29 hours, within 28 hours, within 27 hours, within 26 hours, within 25 hours, within 24 hours.

The total fading time is the total fading time when the heat treatment and the slow cooling treatment are performed once, and when the heat treatment and the slow cooling treatment are performed multiple times, it is the total fading time for each time. For example, when the first fading time is 12 hours and the second fading time is 6 hours, the total fading time is 18 hours.

It should be noted that in the above heat treatment, considering that a plurality of glasses with different glass transition temperatures (Tg) are heat treated together, the heat treatment temperature is set to a temperature lower than the glass transition temperature (Tg) by 5 to 15°C. . Therefore, in the glass according to this embodiment, as long as the reduced glass sample obtained as described above is heat-treated at a heat treatment temperature 5 to 15°C lower than the glass transition temperature (Tg), the discoloration time can be within 48 hours. The reduced color can be sufficiently reduced, that is, as long as the heat treatment is performed at a heat treatment temperature that is at least 15°C lower than the glass transition temperature (Tg), the reduced color can be sufficiently reduced within the fading time within 48 hours.

Here, the so-called glass end is a part that is in the range of 0 to 5 mm from the longitudinal end in a plan view and a distance of 0 to 5 mm from the lateral end. 6~11mm It’s a part of the range of 4-9mm from one end in the horizontal direction.

_{Heat treatment and slow cooling treatment are performed until the external transmittance (T A} ) at the end of the glass at a wavelength of 656 nm when light is incident parallel to the thickness direction and the external transmittance (T _B ) at the center of the glass are calculated by the following formula (2) Above the value (T ₁ ). _{The external transmittance (T A} ) at the end of the glass and the external transmittance (T _B ) at the center of the glass at a wavelength of 656 nm are preferably greater than or _{equal to the value (T 2} ) calculated by the following formula (3), more preferably _{The value (T 3} ) calculated by the following formula (4) is _{greater than or equal to, and more preferably the value T 4} calculated by the following formula (5) is greater than or equal to.

T ₂ =0.84×{1-{(n _C -1)/(n _C +1)} ² } ² ×98. . . Formula (3)

T ₃ =0.85×{1-{(n _C -1)/(n _C +1)} ² } ² ×98. . . Formula (4)

T ₄ =0.86×{1-{(n _C -1)/(n _C +1)} ² } ² ×98. . . Formula (5)

In addition, the difference (T _A -T _B ) between the external transmittance (T _A ) at the end of the glass and the external transmittance (T _B ) at the center of the glass (T A -T B) of 5% or less means that the reduced color of the entire glass is almost uniformly reduced. .

In the heat treatment, the reduction of the reduced color of the glass proceeds from the surface of the glass to the center. Therefore, during the heat treatment, the center portion of the glass is more colored than the end portion of the glass. When the primary color is also reduced by the same extent with the center portion of the glass of the glass ends, i.e., primary colors even further reduced, the external transmittance (T _B) of the external transmittance (T _A) and the center of the glass portion of the end portion of the glass difference ( T _A -T _B ) is 5% or less.

In the glass according to the second embodiment, heat treatment and slow cooling are performed until the difference (T _A -T _B ) between _{the external transmittance (T A} ) at the end of the glass and the external transmittance (T _{B) at the center of the glass is 5} % Or less, preferably 4% or less, more preferably 3% or less, still more preferably 2% or less, still more preferably 1% or less, and still more preferably 0.5% or less.

_{That is, in the glass according to the second embodiment, the external transmittance (T A} ) at the end of the glass and the external transmittance (T _B ) at the center of the glass when the heat treatment and slow cooling treatment are performed until a wavelength of 656 nm are given by the above formula (2) The calculated value (T ₁ ) or more, and the difference (T _A -T _B ) is 5% or less. It is preferable to perform heat treatment and slow cooling until the external transmittance (T _A ) and the external transmittance (T _{B ) are more than the value (T 1} ) calculated by the above formula (2), and the difference (T _A -T _B ) is 4% or less , And furthermore, 3% or less, 2% or less, 1% or less, 0.5% or less. The difference (T _A -T _B ) is as small as possible.

In addition, it is preferable that in the glass according to the second embodiment, heat treatment and slow cooling treatment are performed until the external transmittance (T _A ) at the end of the glass at a wavelength of 656 nm and the external transmittance (T _B ) at the center of the glass are derived from the above _{The value (T 2} ) or more calculated by the formula (3) and the difference (T _A -T _B ) are 5% or less. It is better to perform heat treatment and slow cooling until the external transmittance (T _A ) and external transmittance (T _{B ) are more than the value (T 2} ) calculated by the above formula (3), and the difference (T _A -T _B ) is 4% or less , And furthermore, 3% or less, 2% or less, 1% or less, 0.5% or less. The difference (T _A -T _B ) is as small as possible.

Preferably, in the glass according to the second embodiment, heat treatment and slow cooling treatment are performed until the external transmittance (T _A ) at the end of the glass and the external transmittance (T _B ) at the center of the glass at a wavelength of 656 nm are given by the formula ( 4) The calculated value (T ₃ ) or more, and the difference (T _A -T _B ) is 5% or less. It is better to perform heat treatment and slow cooling treatment until the external transmittance (T _A ) and external transmittance (T _{B ) are more than the value (T 3} ) calculated by the above formula (4), and the difference (T _A -T _B ) is 4% or less , And furthermore, 3% or less, 2% or less, 1% or less, 0.5% or less. The difference (T _A -T _B ) is as small as possible.

Preferably, in the glass according to the second embodiment, the external transmittance (T _A ) at the end of the glass and the external transmittance (T _B ) at the center of the glass after heat treatment and slow cooling treatment at a wavelength of 656 nm are given by the formula ( 5) The calculated value (T ₄ ) or more, and the difference (T _A -T _B ) is 5% or less. Better heat treatment and slow cooling process until the external transmittance T _A and T _B by the external transmittance value calculated by the formula (5) (T ₄₎ above, the difference (T _A -T _B) is 4% or less, 3 % Or less, 2% or less, 1% or less, 0.5% or less. The difference (T _A -T _B ) is as small as possible.

In the glass according to the second embodiment, the shorter the fading time, the better. Thus, in the preferred manner, in the heat treatment and slow cooling process, the fade time is 24 hours or less, the external transmittance (T _B) external transmittance (T _A) a glass end portion at a wavelength of 656nm and the center portion of the glass _{The value (T 4} ) or more and the difference (T _A -T _B ) calculated from the above formula (5) are 0.5% or less.

The external transmittance is measured based on the standards of the Japan Optical Glass Industry Association (JOGIS 02-2003). In the measurement of external transmittance, incident light was irradiated perpendicularly to the upper surface (a surface with a length of 17 mm and a width of 13 mm). In addition, the area where the incident light is irradiated to the glass end portion and the glass center portion is irradiated so as to be condensed in a range of 5 mm×5 mm.

In the glass according to the second embodiment, the lower limit of the total content of _{TiO 2} , Nb ₂ O ₅ , WO ₃ and Bi ₂ O _{3 [TiO 2} +Nb ₂ O ₅ +WO ₃ +Bi ₂ O _{3] is preferable} 35%, and then more preferably 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62% , 64%. In addition, the upper limit of the total content [TiO ₂ +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ ] is preferably 90%, and more preferably 88%, 86%, 85%, 84%, 83%, 82%. %, 81%, 80%, 79%, 78%, 77%.

TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ contribute to the high dispersion of glass. In addition, by containing it in an appropriate amount, it also has an effect of improving the thermal stability of the glass. Therefore, the lower limit of the total content [TiO ₂ +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ ] is preferably the above range. On the other hand, TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ increase the coloring of the glass. Therefore, the upper limit of the total content [TiO ₂ +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ ] is preferably within the above range.

In addition, in the glass according to the second embodiment, when the content of the glass component is expressed in cationic %, the total content of ^{Ti 4+} , Nb ⁵⁺ , W ⁶⁺ and Bi ^{3+ [Ti 4+} +Nb ⁵⁺ + The lower limit of W ⁶⁺ +Bi ³⁺ ] is preferably 52.00 cationic%, and more preferably 52.10 cationic%, 52.15 cationic%, 52.20 cationic%, 52.25 cationic%, 52.30 cationic% in order. The upper limit of the total content [Ti ⁴⁺ +Nb ⁵⁺ +W ⁶⁺ +Bi ³⁺ ] is preferably 75.00 cationic%, and more preferably 74.50 cationic%, 74.00 cationic%, 73.50 cationic%, 73.00 cationic%, 72.50 Cationic%, 72.00 cationic%, 71.50 cationic%, 71.00 cationic%, 70.50 cationic%.

Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ contribute to the high dispersion of glass. In addition, by containing it in an appropriate amount, it also has an effect of improving the thermal stability of the glass. Therefore, the lower limit of the total content [Ti ⁴⁺ +Nb ⁵⁺ +W ⁶⁺ +Bi ³⁺ ] is preferably the above range. On the other hand, Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ increase the coloring of the glass. Therefore, the upper limit of the total content [Ti ⁴⁺ +Nb ⁵⁺ +W ⁶⁺ +Bi ³⁺ ] is preferably the above range.

In the glass according to the second embodiment, _{the upper limit of the content of Bi 2} O ₃ is preferably 38%, and more preferably 35%, 33%, 30%, 28%, 25%, 23%, 20%. . In addition, the lower limit of the content of _{Bi 2} O _{3 is preferably 0%.} The content of Bi ₂ O ₃ may be 0%.

Bi ₂ O ₃ is a component that contributes to high dispersion. In addition, by setting _{the content of Bi 2} O ₃ in the above range, it is possible to suppress an increase in specific gravity and a decrease in glass transition temperature (Tg). When the specific gravity of the glass increases, the quality of the optical element increases. For example, if a high-quality lens is assembled into an auto-focus type photographic lens, the power required to drive the lens during auto-focusing will increase, and battery consumption will increase. Therefore, it is preferable to _{set the content of Bi 2} O ₃ within the above-mentioned range.

In addition, in the glass according to the second embodiment, when the content of the glass component is expressed in cationic %, ^{the upper limit of the Bi 3+} content is preferably 10.00 cationic%, and more preferably 9.00 cationic%, 8.00 cationic%, 7.00 cationic%, 6.00 cationic%, 5.00 cationic%, 4.50 cationic%, 4.00 cationic%, 3.50 cationic%, 3.00 cationic%, 2.50 cationic%, 2.00 cationic%, 1.50 cationic%, 1.00 cationic%. The content of Bi ³⁺ can be 0 cationic %.

Bi ³⁺ is a component that contributes to high dispersion. In addition, by setting ^{the content of Bi 3+} in the above range, it is possible to suppress an increase in specific gravity and a decrease in the glass transition temperature (Tg). When the specific gravity of the glass increases, the quality of the optical element increases. For example, if a high-quality lens is assembled into an auto-focus type photographic lens, the power required to drive the lens during auto-focusing will increase, and battery consumption will increase. Therefore, it is preferable to ^{set the content of Bi 3+} to the above-mentioned range.

In the glass of the second embodiment relates in, Li ₂ O content and the _{2, 2} O _5, the total content of WO ₃ and Bi ₂ O ₃ of Nb TiO mass ratio of _{[Li 2 O / (TiO 2 +} Nb 2 O ₅ +WO ₃ +Bi ₂ O ₃ )] The lower limit of the value multiplied by 100 is preferably 0.017, and more preferably 0.019, 0.021, 0.023, 0.025, 0.027, 0.030 in order. In addition, the upper limit of the mass ratio [Li ₂ O/(TiO ₂ +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ )] multiplied by 100 is preferably 0.750, and more preferably 0.730, 0.710, 0.700, 0.680, 0.650, 0.600, 0.550.

In the glass according to the second embodiment, when the content of the glass component is expressed in cationic %, when the content of W ⁶⁺ exceeds 0 cationic %, the cationic ratio of the content of ^{Ba 2+ to} the content of W ^{6+ [Ba The upper limit of 2+} /W ⁶⁺ ] is preferably 0.14, and more preferably 0.13, 0.12, 0.11, and 0.10 in this order.

Ba ²⁺ is a component that contributes to low dispersion. Therefore, in the glass according to the second embodiment ^{, W 6+} as a high-dispersion component ^{relative to the content of Ba 2+} is contained so as to have the above-mentioned cation ratio, so that the desired high-dispersibility can be maintained.

In addition, in the glass according to the second embodiment, when the content of the glass component is expressed in cationic %, when ^{the content of W 6+} is 0 cationic% and ^{the content of Ba 2+} exceeds 0 cationic%, Ti ⁴⁺ The upper limit of the total content of Bi ^{3+ [Ti 4+} +Bi ³⁺ ] is preferably 35.00 cationic%, and more preferably 34.00 cationic%, 33.00 cationic%, 32.50 cationic%, 32.30 cationic%, 32.00 cationic%, 31.80 cationic%, 31.60 cationic%, 31.40 cationic%, 31.20 cationic%, 31.00 cationic%, 30.80 cationic%, 30.60 cationic%, 30.40 cationic%, 30.20 cationic%, 30.10 cationic%, 30.00 cationic%. The lower limit of the total content [Ti ⁴⁺ +Bi ³⁺ ] is preferably 21.00 cationic%, and more preferably 21.20 cationic%, 21.40 cationic%, 21.60 cationic%, 21.80 cationic%, 22.00 cationic%, 22.20 cationic%, 22.40 Cationic%, 22.60 cationic%, 22.80 cationic%, 23.00 cationic%, 23.10 cationic%, 23.20 cationic%, 23.30 cationic%, 23.40 cationic%, 23.50 cationic%.

In ^{the case where the content of W 6+} is 0 cationic% and ^{the content of Ba 2+ exceeds 0 cationic %, Ti 4+} , which is second only to W ⁶⁺ in the high-dispersion components, contributes to high-dispersion, and has improved ^{By setting the total content of Bi 3+} as a function of thermal stability in the above range, it is possible to suppress the decrease in dispersion ^{due to Ba 2+.}

The other glass components in the second embodiment can be the same as those in the first embodiment. In addition, the production of glass characteristics, glass, optical glass, glass material for polishing, glass material for press molding, optical element, etc. in the second embodiment can also be the same as in the first embodiment.

The embodiments of the present invention have been described above, but the present invention is not limited to such embodiments at all, and can be implemented in various ways within the scope not departing from the gist of the present invention.

Example

Hereinafter, the present invention will be described with examples, but the present invention is not limited to the following examples.

Example 1 and Example 2 are examples corresponding to the first embodiment, and Example 3 and Example 4 are examples corresponding to the second embodiment.

Here, in Example 1, Table 1A shows the glass composition in mass% and Table 1B shows the cation% in the glass samples A to D. That is, in Table 1A and Table 1B, the glass composition representation method is different, but the glass with the same number has the same composition. Therefore, Table 1A and Table 1B show substantially the same glass.

Similarly, in Example 2, Tables 3A-1 to 3A-8 are expressed in mass %, and Tables 3B-1 to 3B-8 are expressed in cation% to show the glass compositions of the glass samples 1 to 109. That is, in Tables 3A-1 to 3A-8 and Tables 3B-1 to 3B-8, the expression methods of the glass composition are different, but glasses with the same number have the same composition. because Therefore, Tables 3A-1 to 3A-8 and Tables 3B-1 to 3B-8 show substantially the same glass.

In addition, in Table 1B and Tables 3B-1 to 3B-8, the glass composition is represented by the cation% expression when ^{the total amount of the anion component is O 2-.} That is, in Table 1B and Tables 3B-1 to 3B-8, ^{the content of O 2-} is 100 anion%.

(Example 1)

〔Production of glass samples〕

The raw materials are weighed and blended so that the composition of the obtained glass becomes the composition shown in Table 1A and Table 1B, and the resulting blended raw material (batch raw material) is put into a platinum crucible, and the temperature is 1300~1350℃ in the atmosphere. It is heated for 90 minutes for melting, homogenization is performed by stirring, and clarification is performed to obtain molten glass. The molten glass was cast into a forming mold for forming, slowly cooled, ground, and polished to a length of 17 mm, a width of 12 mm, and a thickness of 10 mm to obtain a glass sample. At this time, the upper surface and the lower surface (a surface with a length of 17 mm and a width of 12 mm) were optically polished.

The obtained glass sample exhibited a reduced color.

[Evaluation of glass samples]

For the obtained glass samples, the confirmation of glass composition, refractive index (n _d and n _C ), Abbe number ( v _d ), glass transition temperature (Tg), liquidus temperature (LT ), the value of βOH, and measure the retention time at the heat treatment temperature and the transmittance after the heat treatment required to sufficiently reduce the reduced color.

(1) Confirmation of glass composition

Select an appropriate amount of glass samples obtained as described above, and subject them to acid and alkali treatments. _{The content of Li 2} O is measured by ICP-MS, and _{the content of glass components other than Li 2} O is measured by ICP-AES. It is consistent with the composition of each oxide shown in Table 1B.

(2) Refractive index (n _d and n _C ), Abbe number ( v _d )

After the glass sample was kept in the atmosphere at around the glass transition temperature (Tg) for 48 hours, it was slowly cooled at a temperature drop rate of 30°C/hour, and then left to cool to reduce coloration. _{The obtained sample was processed into a prism, and the refractive index (n d} ), refractive index (n _F ), and refractive index (n _C ) were measured based on the refractive index measurement method of the Japan Optical Glass Industry Association. In addition, the Abbe number (v _d ) was calculated using the respective measured values of the _{refractive index (n d} ), refractive index (n _F ), and refractive index (n _{C ).} The results are shown in Table 1A.

〔3〕Glass transition temperature (Tg)

A thermomechanical analyzer manufactured by Rigaku Corporation was used to measure the temperature increase rate at 10°C/min. The results are shown in Table 1A.

(4) Liquidus temperature

Put a 10cc (10ml) glass sample into a platinum crucible, melt it at 1250°C to 1350°C for 20 to 30 minutes, then cool it to below the glass transition temperature (Tg), and put the glass together with the platinum crucible to the specified temperature. The melting furnace was kept for 2 hours. The holding temperature was set to 1000°C or higher on a scale of every 10°C, and the lowest temperature at which there was no precipitation of crystals after holding for 2 hours was set as the liquidus temperature. Set the result as Table 1A.

〔5〕βOH

The glass sample is processed into a plate shape with a thickness of 1 mm that is parallel and flat on both sides and optically polished. Light is incident from the perpendicular direction to the optically polished surface, and the external transmittance C at a wavelength of 2500nm and the external transmittance D at a wavelength of 2900nm are measured using a spectrophotometer (UV-3100, manufactured by Shimadzu), using the following formula (1) To calculate βOH.

βOH=-〔ln(D/C)〕/t. . . Formula 1)

In the above formula (1), ln is a natural logarithm, and the thickness (t) corresponds to the distance between the two planes. The results are shown in Table 1A.

〔6〕Holding time at the heat treatment temperature

The above-mentioned glass sample exhibiting a reduced color is heat-treated. That is, in an air atmosphere, heating is performed at a temperature increase rate of 100°C/hour, and heat treatment is performed at a heat treatment temperature 5-15°C lower than the glass transition temperature (Tg) for a predetermined time, and the temperature is gradually reduced at a rate of 30°C/hour. Cool to a temperature 120°C lower than the above heat treatment temperature. The heat treatment and slow cooling are repeated until the reduced color of the glass sample is sufficiently reduced. When the reduced color is reduced and the color becomes uniform, it is evaluated that the reduced color is sufficiently reduced. Table 2 shows the total of the retention time at the heat treatment temperature required for the reduced color to be sufficiently reduced.

〔7〕Transmittance after heat treatment

The external transmittance of the glass sample whose color was reduced by heat treatment and became uniform was measured. Light was incident from a direction perpendicular to the optically polished surface, and the external transmittance at a wavelength of 656 nm was measured using a spectrophotometer (UV-3150, manufactured by Shimadzu). The results are shown in Table 2.

(Example 2)

〔Production of glass samples〕

The composition of the obtained glass becomes Table 3A-1~3A-8 and Table 3B-1~3B-8 In the form of each composition shown, except that water vapor was applied to a molten atmosphere to obtain a molten glass, it carried out similarly to Example 1, and produced a glass sample.

The obtained glass sample exhibited a reduced color.

[Evaluation of glass samples]

For the obtained glass sample, the confirmation of glass composition, refractive index (n _d and n _C ), Abbe number (ν _d ), glass transition temperature (Tg), and liquidus temperature were measured in the same manner as in Example 1. The values of (LT) and βOH are measured for the retention time at the heat treatment temperature and the transmittance after the heat treatment required to sufficiently reduce the reduced color. The results are shown in Tables 3A-1 to 3A-8, Tables 3B-1 to 3B-8, and Tables 4-1 to 4-8.

(Example 3)

[Preparation of reduced glass samples]

The glass samples (samples A to D) obtained in Example 1 were heated at 1300° C. in an air atmosphere for 90 minutes to be remelted, homogenized by stirring, and clarified to obtain molten glass. The molten glass is poured into a molding die for molding, and the sample is kept at a holding temperature of 0-20°C lower than the glass transition temperature (Tg) for 15 minutes in an atmospheric atmosphere, and slowly cooled to a temperature of 30°C/h At a temperature lower than the above-mentioned holding temperature by 120°C, it was ground and polished to a length of 17 mm, a width of 12 mm, and a thickness of 10 mm to obtain a reduced glass sample. At this time, the upper surface and the lower surface (a surface with a length of 17 mm and a width of 12 mm) were optically polished.

The obtained reduced glass sample exhibited reduced color.

[Evaluation of reduced glass samples]

The obtained reduced glass sample is heated at a heating rate of 100°C/hour in an air atmosphere, and heat treated at a heat treatment temperature 5-15°C lower than the glass transition temperature (Tg) for a predetermined time, at 30°C/hour The cooling rate is slow cooling treatment to a temperature 120°C lower than the above heat treatment temperature. Slow cooling process is repeated until the external heat transmittance of the glass end portions (T _A) and the external transmittance (T _B) of the center portion of the glass difference (T _A -T _B) is 5% or less. For external transmittance (T _A) and (T _B), with respect to the incident light from the optically polished surface is vertical, the external transmittance measured at a wavelength of 656nm using a spectrophotometer (UV-3150, Shimadzu Corporation).

The difference (T _A -T _B) external transmittance (T _B) of the external transmittance (T _A) and the end portion of the glass in the central portion of the glass at the heat treatment temperature holding time is less than 5% until the total required and The external transmittance (T _A ) and (T _B ) are shown in Table 5.

(Example 4)

[Preparation of reduced glass samples]

The glass samples obtained in Example 2 (sample numbers 1 to 20, 22 to 32, 42, 44 to 52, 54, 57 to 80, 88 to 95) were remelted in the same manner as in Example 3 to obtain a reduction Glass samples.

The obtained reduced glass sample exhibited reduced color.

[Evaluation of reduced glass samples]

For the obtained reduced glass sample, the difference (T _A- T _B ) between _{the external transmittance (T A} ) at the end of the glass and the external transmittance (T _B ) at the center of the glass was measured in the same manner as in Example 3. The total of the holding time at the heat treatment temperature and the external transmittance (T _A ) and (T _B ) required up to %. The results are shown in Tables 6-1 to 6-6.

Claims (17)

A glass whose Abbe number (ν _d ) is 18.10 or less; and the total content of _{TiO 2} , Nb ₂ O ₅ , WO ₃ and Bi ₂ O _{3 [TiO 2} +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ ] 30% by mass or more; and ^{phosphate glass with a Bi 3+} content of 10 cationic% or less; and _{the content of Li 2} O and the total content of TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ The mass ratio [Li ₂ O/(TiO ₂ +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ )] multiplied by 100 is 0.015 to 0.770. A glass having an Abbe number (ν _d ) of 18.10 or less; and containing at least one oxide _{selected from the group consisting of TiO 2} , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ ^{and having a Bi 3+} content of 10 Phosphate glass with cationic% or less; and in an atmospheric atmosphere at a temperature higher than the liquidus temperature (LT) 110~120℃ for another 90 minutes and molded, in an atmospheric atmosphere at a temperature higher than the glass transition temperature (Tg ) The glass is processed into a glass with a length of 17mm, a width of 13mm, and a thickness of 10mm. ; And the part in the range of 0~5mm from the longitudinal end in plan view and the range of 0~5mm from the lateral end is defined as the glass end, and the distance from the longitudinal end in plan view is 6~11mm And when the part in the range of 4-9mm from the lateral end is set as the center of the glass; and it will be heated at a heating rate of 100°C/h in an atmospheric atmosphere and lower than the glass transition temperature (Tg) The heat treatment maintained at a heat treatment temperature of 5 to 15°C and the slow cooling treatment at a temperature drop rate of 30°C/h to a temperature 120°C lower than the heat treatment temperature are performed once or repeatedly until light is incident parallel to the thickness direction external transmittance wavelength (T _a) when the end portion of the glass at 656nm and the transmittance of the glass of the outer central portion (T _B) is a value (2) calculated by the following formula (T ₁₎ above, and the The difference (T _A -T _B ) between the external transmittance (T _A ) of the end of the glass and the external transmittance (T _B ) of the center of the glass (T A -T B) is less than 5%. At this time, the heat treatment is held at the heat treatment temperature for the time The total of is within 48 hours; T ₁ =0.83×{1-{(n _C -1)/(n _C +1)} ² } ² ×98. . . In Formula (2) Formula (2), n _C is the heat treatment and slow cooling process until the external transmittance (T _A) of the glass end portions and the external transmittance (T _B) of the center of the glass portion of the difference (T _A - The refractive index at a wavelength of 656.27 nm when T _{B) is 5% or less.} For the glass described in item 1 or 2 of the scope of patent application, _{the content of Li 2} O is 0.010% by mass or more. For the glass described in item 1 or 2 of the scope of patent application, _{the content of Li 2} O is 0.640 mass% or less. For the glass described in item 1 or 2 of the scope of patent application, the value of βOH represented by the following formula (1) is 0.05mm ^-1 or more: βOH=-[ln(D/C)]/t. . . In formula (1) and formula (1), t represents the thickness (mm) of the glass used in the measurement of external transmittance, and C represents the external transmittance ( %), D represents the external transmittance (%) at a wavelength of 2900 nm when light is incident on the glass parallel to its thickness direction. The glass described in item 1 or 2 of the scope of patent application contains Nb ₂ O ₅ as the glass component. The glass described in item 1 or 2 of the scope of patent application contains TiO ₂ as the glass component. For the glass described in item 1 or 2 of the scope of patent application, _{the content of Bi 2} O ₃ is 20% by mass or less. An optical glass formed from the glass described in any one of items 1 to 8 in the scope of patent application. A glass material for polishing, which is formed from the glass described in any one of items 1 to 8 of the patent application. A glass material for press molding is formed from the glass described in any one of items 1 to 8 in the scope of patent application. A glass material for polishing, formed from the optical glass described in item 9 of the scope of patent application. A glass material for press molding, which is formed of the optical glass described in item 9 of the scope of patent application. An optical element formed of the glass described in any one of the patent applications 1 to 8. An optical element formed by the optical glass described in item 9 of the scope of patent application. An optical element formed of the polishing glass material described in item 10 or 12 of the scope of patent application. An optical element formed of the press-forming glass material described in item 11 or 13 of the scope of patent application.