TWI691470B - Optical glass and optical components - Google Patents

Abstract

2.25-0.01×νd。 An object of the present invention is to provide an optical glass that can reduce production costs such as raw material costs, is excellent in meltability and thermal stability, and has high refractive index and low dispersion with low-temperature softening. The optical glass is oxide glass, expressed as cation %, and the total content [B ³⁺ +Si ⁴⁺ +La ³⁺ +Gd ³⁺ +Y ³⁺ +Yb ³⁺ ] is 65% or more; the cation ratio (α) 0.30~0.70; the cation ratio (β) is less than 1 and does not include 0; the total content [Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Ta ⁵⁺ +Bi ³⁺ ] is less than 7%; the cation ratio (γ) is 0.5 or more; value (L) is 24 or more; Abbe number (νd) is 43.5 to 47; relative to this Abbe number (νd), the refractive index (nd) satisfies the following formula (1): nd

2.25-0.01×νd.

Description

Optical glass and optical components

The invention relates to an optical glass, which can reduce the manufacturing cost, meltability and thermal stability, and has high refractive index and low dispersion. In addition, the present invention relates to an optical element composed of the optical glass.

Generally, high refractive index and low dispersion optical glass contains oxides of rare earth elements such as boron oxide and lanthanum oxide. In such optical glass, in order to increase the refractive index without reducing the Abbe number (νd), it is necessary to increase the content of the oxide of the rare earth element. However, in such optical glass, when the content of oxides of rare earth elements is increased, there is a decrease in the thermal stability of the glass, the glass will crystallize during the glass manufacturing process, and it is difficult to obtain transparent glass (glass devitrification ( Devitrification)).

On the other hand, in the design of an optical system, an optical glass with a high refractive index and a large Abbe number is of high use value in correcting chromatic aberration, making the optical system highly functional, and compact. In particular, it has A (45, 1.80) and B (40, located in the connection (Abbe number (νd), refractive index (nd)) in the optical characteristic diagram (also called nd-νd diagram or Abbe diagram). The glass on the straight line C at the two points of 1.85) and the range of refractive index nd is higher than that of the straight line C has high optical design value.

In the optical glass having the above-mentioned high refractive index and low dispersion characteristics, the glass transition temperature (Tg) (hereinafter, sometimes simply referred to as "Tg") is low and suitable for fine The compacted glass contains a large amount of zinc (Zn) and lithium (Li), which softens at low temperatures (Patent Documents 1 to 5). However, the glass containing a large amount of oxides of Zn, Li, and rare earth elements has reduced thermal stability, crystals are precipitated during the manufacturing process, and they become easily devitrified.

In order not to reduce the refractive index and thermal stability as the glass transition temperature (Tg) decreases, the prior art needs to contain a large amount of tantalum oxide as a glass component. However, tantalum oxide is rare and high in value, and it is not easy to obtain a stable supply as a glass raw material. Therefore, the price of tantalum oxide is extremely high, which causes the manufacturing cost (raw material cost) of the optical glass to increase.

[Prior Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. 6-305769.

Patent Document 2: Japanese Patent Laid-Open No. 8-026765.

Patent Document 3: Japanese Patent Laid-Open No. 2005-272194.

Patent Document 4: Japanese Patent Laid-Open No. 56-54251.

Patent Document 5: Japanese Patent Application Publication No. 2002-249337.

The present invention has been completed in view of such actual circumstances, and an object of the present invention is to provide an optical glass which can reduce production costs such as raw material costs, is excellent in meltability and thermal stability, and has a low refractive index, high refractive index and low Dispersion. Furthermore, another object of the present invention is to provide an optical element and optical glass material composed of such optical glass.

The present inventors have conducted repeated and in-depth studies in order to achieve the above object, and as a result, they have found that this object can be achieved by reducing the amount of tantalum oxide, which is a relatively expensive material, and adjusting the balance of the content ratios of various components constituting glass. The present invention has been completed based on this knowledge.

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

2.25-0.01×νd。 [1] An optical glass, which is an oxide glass, expressed as cation %, the total content of B ³⁺ , Si ⁴⁺ , La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ [B ³⁺ +Si ⁴⁺ +La ³⁺ +Gd ³⁺ +Y ³⁺ +Yb ³⁺ ] is 65% or more; the total content of La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ is relative to B ³⁺ , The cation ratio (α) of the total content of Si ⁴⁺ and Al ³⁺ = [(La ³⁺ +Gd ³⁺ +Y ³⁺ +Yb ³⁺ )/(B ³⁺ +Si ⁴⁺ +Al ³⁺ )] 0.30 to 0.70; with respect to the content of La ³⁺ La ^3+, the total cation content of Gd ^3+, Y ³⁺ and Yb ³⁺ ratio ^{(β) = [La 3+ /} (La 3+ + Gd 3+ +Y ³⁺ +Yb ³⁺ )] less than 1 and excluding 0; the total content of Nb ⁵⁺ , Ti ⁴⁺ , W ⁶⁺ , Ta ⁵⁺ and Bi ³⁺ [Nb ⁵⁺ +Ti ⁴⁺ +W ^{6 + +} Ta ^{5+ +} Bi ^3+] less than 7%; the content of Nb ⁵⁺ cation with respect to the total content of Nb ⁵⁺ and Ta ⁵⁺ ratio ^{(γ) = [Nb 5+ /} (Nb 5+ + Ta 5 ⁺ )] is 0.5 or more; the sum of 6 times the content of Li ⁺ and 2 times the content of Zn ²⁺ minus the content of Si ⁴⁺ (L)=[(6×Li ⁺ )+(2×Zn ²⁺ )-Si ⁴⁺ ] is 24 or more; Abbe number (νd) is 43.5 to 47; relative to this Abbe number (νd), the refractive index (nd) satisfies the following formula (1): nd

2.25-0.01×νd.

[2] The optical glass as described in [1] above, wherein the content of Zr ⁴⁺ is 0.1 to 10 cationic %.

2.25-0.01×νd [3] An optical glass containing B ₂ O ₃ , La ₂ O ₃ and Nb ₂ O ₅ as essential components; the ratio [RE'/NWF'] of the value (RE') to the value (NWF') is 0.30~ 0.70; value (HR ') ratio (the value RE) with respect to the' [HR '/ RE'] is 0.30 or less; the content of La ₂ O ₃ with respect to _{La 2 O 3, Gd 2 O} 3, Y 2 O 3 and The mass ratio of the total content of Yb ₂ O ₃ (βw)=[La ₂ O ₃ /(La ₂ O ₃ +Gd ₂ O ₃ +Y ₂ O ₃ +Yb ₂ O ₃ )] is less than 1 and does not include 0; Nb ₂ O ₅ content with respect to the mass of the total content of Nb ₂ O ₅ and Ta ₂ O ₅ ratio _{(γw) = [Nb 2 O} 5 / (Nb 2 O 5 + Ta 2 O 5)] is more than 2/3; The value (L') is -0.10 or more; the Abbe number (νd) is 43.5 to 47; with respect to the Abbe number (νd), the refractive index (nd) satisfies the following formula (1): nd

2.25-0.01×νd

In the formula: B ₂ O ₃ , SiO ₂ , Al ₂ O ₃ , La ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ , Yb ₂ O ₃ , Nb ₂ O ₅ , TiO ₂ , WO ₃ , Bi ₂ The molecular weights of O ₃ , Li ₂ O, Na ₂ O, K ₂ O, and ZnO are expressed as M(B ₂ O ₃ ), M(SiO ₂ ), M(Al ₂ O ₃ ), and M(La ₂ O ₃ ), M(Gd ₂ O ₃ ), M(Y ₂ O ₃ ), M(Yb ₂ O ₃ ), M(Nb ₂ O ₅ ), M(TiO ₂ ), M(WO ₃ ), M(Bi ₂ O ₃ ), M (Li ₂ O), M (Na ₂ O), M (K ₂ O), and M (ZnO); in the content ratio of each of the above components expressed in mass% when the value represented: the above value (NWF ') is twice the value of the content of B ₂ O ₃ is divided by M (B ₂ O ₃₎ value, the value of the content of SiO ₂ is divided by M (SiO ₂ ) the total value of the value of dividing the value of Al ₂ O ₃ by 2 times the value of M (Al ₂ O ₃ ); the above value (RE′) is ₂ of the value of the content of La ₂ O ₃ Times divided by the value of M(La ₂ O ₃ ), divided twice the value of the content of Gd ₂ O ₃ by the value of M(Gd ₂ O ₃ ), and divided by twice the value of the content of Y ₂ O ₃ 2-fold and the value of Yb ₂ O ₃ content value M (Y ₂ O ₃₎ is divided by M (Yb ₂ O ₃₎ a sum of values; and the value (HR ') of the Nb ₂ O ₅ 2 times the value of the content is divided by M (Nb ₂ O ₅₎ values, the value of the content of TiO ₂ is divided by M (TiO ₂₎ values, the value of the content of WO ₃ is divided by M (WO ₃₎ And the total value of the value divided by 2 times the value of Bi ₂ O ₃ content divided by the value of M(Bi ₂ O ₃ ); the above value (L′) is the value divided by 12 times the value of the content of Li ₂ O divided by The value of M(Li ₂ O) is divided by 4 times the value of Na ₂ O content by the value of M(Na ₂ O), and the value of K ₂ O content is doubled by M(K ₂ O) and 2 times the value of the content of ZnO is divided by M (ZnO) by subtracting the total value of twice the value of the content of SiO ₂ is divided by M (SiO ₂₎ the value of the Al ₂ O ₃ 2-fold amount divided by the value M (Al ₂ O ₃₎ and the numerical value of the content of B ₂ O ₃ is divided by M (B ₂ O ₃₎ the value of the total value of the values.

[4] The optical glass as described in [3] above, wherein the content of ZrO ₂ is 0.1 to 15% by mass.

[5] The optical glass according to any one of the above [1] to [4], wherein the content of Sb ₂ O ₃ is less than 1% by mass.

[6] An optical element comprising the optical glass according to any one of the above [1] to [5].

[7] A preform for precision press molding, which is composed of the optical glass according to any one of the above [1] to [5].

According to the present invention, it is possible to provide an optical glass with high refractive index and low dispersion that can reduce production costs, is excellent in meltability and thermal stability, and has low-temperature softening, and an optical element using the optical glass.

FIG. 1 is a graph plotted for a well-known glass using the horizontal axis as the value (L) and the vertical axis as the glass transition temperature (Tg).

Fig. 2 is a graph plotted for a known glass with the horizontal axis as the value (L') and the vertical axis as the glass transition temperature (Tg).

Hereinafter, an embodiment for implementing the present invention (hereinafter, simply referred to as "embodiment") will be described in detail. The following embodiment is an example for explaining the present invention, and the gist of the present invention is not limited to the following. The present invention can be suitably modified and implemented within the scope of the gist thereof. Furthermore, in the case where the description overlaps, the description may be omitted as appropriate, but the gist of the invention is not limited. In addition, in this specification, the form and size of optical glass are not limited. In addition, in this specification, optical glass is sometimes just referred to as "glass".

First embodiment

2.25-0.01×νd。 The optical glass of this embodiment is an oxide glass, which is characterized by cation %, and the total content of B ³⁺ , Si ⁴⁺ , La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ [B ³⁺ + Si ⁴⁺ +La ³⁺ +Gd ³⁺ +Y ³⁺ +Yb ³⁺ ] is 65% or more; the total content of La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ is relative to B ³⁺ and Si The cation ratio of the total content of ⁴⁺ and Al ³⁺ (α)=[(La ³⁺ +Gd ³⁺ +Y ³⁺ +Yb ³⁺ )/(B ³⁺ +Si ⁴⁺ +Al ³⁺ )] is 0.30 to 0.70; with respect to the content of La ³⁺ La ^3+, the total cation content of Gd ^3+, Y ³⁺ and Yb ³⁺ ratio ^{(β) = [La 3+ /} (La 3+ + Gd 3+ + Y ³⁺ +Yb ³⁺ )] less than 1 and excluding 0; the total content of Nb ⁵⁺ , Ti ⁴⁺ , W ⁶⁺ , Ta ⁵⁺ and Bi ³⁺ [Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ + Ta ⁵⁺ + Bi ^3+] less than 7%, the Nb ⁵⁺ content to the total content of Nb ⁵⁺ and Ta ⁵⁺ cation ratio ^{(γ) = [Nb 5+ /} (Nb 5+ + Ta 5+ )] is 0.5 or more; the sum of 6 times the content of Li ⁺ and 2 times the content of Zn ²⁺ minus the value of the content of Si ⁴⁺ (L) = [(6×Li ⁺ )+(2×Zn ^{2 +} )-Si ⁴⁺ ] is 24 or more; Abbe number (νd) is 43.5 to 47; relative to this Abbe number (νd), the refractive index (nd) satisfies the following formula (1): nd

2.25-0.01×νd.

In addition, in this embodiment, as the first aspect of the present invention, The optical glass of the present invention will be described based on the content ratio of each component expressed in cation %. Therefore, unless otherwise specified, each content is expressed as a cation %.

In addition, in this specification, as is well known, the expression of cation% refers to the mole percentage when the total content of all cationic components is 100%. The total content refers to the total content of a plurality of cationic components (including the content of 0%). In addition, the 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 the cation% is expressed.

In addition, the valence of the cationic component (for example, the valence of B ^{3+ is +3} , the valence of Si ⁴⁺ is +4, and the valence of La ³⁺ is +3) is a value conventionally determined, and the When oxides are used as the basis for boron (B), silicon (Si), and lanthanum (La) as glass components, they are expressed as boron trioxide (B ₂ O ₃ ), silicon dioxide (SiO ₂ ), and lanthanum trioxide ( La ₂ O ₃ ) is the same. Therefore, when analyzing the glass composition, it is not necessary to analyze the valence of the cationic component. In addition, the valence of the anionic component (for example, the valence of O ^2- is -2) is also a conventionally determined value, and as described above, the glass component based on oxide is expressed as, for example, B ₂ O ₃ , SiO ₂ , La ₂ O ₃ is the same. Therefore, when analyzing the glass composition, it is not necessary to analyze the valence of the anion component.

Hereinafter, the optical glass of this embodiment will be described in detail.

In the optical glass of this embodiment, the total content of B ³⁺ , Si ⁴⁺ , La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ [B ³⁺ +Si ⁴⁺ +La ³⁺ +Gd ^{3 +} +Y ³⁺ +Yb ³⁺ ] is 65% or more.

Among the above components, B ³⁺ and Si ⁴⁺ are network-forming components, which help maintain the thermal stability of the glass. In addition, La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ are rare-earth components, and have the effect of increasing the refractive index (nd) without greatly reducing the Abbe number (νd).

Therefore, in the optical glass of this embodiment, in order to achieve the desired optical characteristics (refractive index (nd) and Abbe number (νd)) while maintaining the thermal stability of the glass in a good state, the total content [ B ³⁺ +Si ⁴⁺ +La ³⁺ +Gd ³⁺ +Y ³⁺ +Yb ³⁺ ] Satisfying the above range is a prerequisite.

In addition, in the optical glass of this embodiment, the total content (RE) of La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ = [La ³⁺ +Gd ³⁺ +Y ³⁺ +Yb ³⁺ ] The ratio of the total content of B ³⁺ , Si ⁴⁺ and Al ³⁺ (NWF)=[B ³⁺ +Si ⁴⁺ +Al ³⁺ ], that is, the cation ratio (α)=[RE/NWF] is 0.30 ~0.70.

La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ have the effect of increasing the refractive index while suppressing the decrease in Abbe number (νd), so when the cation ratio (α) is too small, it is difficult to achieve the desired Optical characteristics. On the other hand, B ³⁺ , Si ⁴⁺ and Al ³⁺ help maintain the thermal stability of the glass. Therefore, when the cation ratio (α) is too large, the thermal stability of the glass will decrease. In addition, the glass transition temperature (Tg ) Will also rise. Therefore, in the optical glass of this embodiment, in order to achieve desired optical characteristics while maintaining thermal stability, the cation ratio (α) is set within the above range. In addition, since the cation ratio (α) is defined as described above, the total content (NWF) does not include 0%.

Further, in the optical glass of the present embodiment aspect, with respect to the content of La ³⁺ La ^3+, the ratio of Gd ^3+, Y ³⁺ and Yb ³⁺ total content (RE), i.e., the cation ratio of (β) = [ La ³⁺ /RE] is less than 1 and does not contain 0.

Compared with Gd ³⁺ , Y ³⁺ and Yb ³⁺ , La ³⁺ is a component that hardly lowers the thermal stability and meltability of the glass even if it is contained in a large amount. Therefore, when the proportion of La ³⁺ in La ³⁺ , Gd ³⁺ , Y ^3+, and Yb ³⁺ is too small, the thermal stability of the glass decreases and the meltability decreases. However, when the contents of La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ are all 0%, it is difficult to obtain high refractive index and low dispersion characteristics. On the other hand, when it is desired to obtain high refractive index and low dispersion characteristics by containing other components, the thermal stability of the glass decreases. Therefore, in the optical glass of the present embodiment, La ^{3+ is} used as an essential component, and in order to maintain thermal stability and meltability well, the cation ratio (β) is within the above range.

In addition, in the optical glass of this embodiment, the total content (HR) of Nb ⁵⁺ , Ti ⁴⁺ , W ⁶⁺ , Ta ⁵⁺ and Bi ³⁺ = [Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ + Ta ⁵⁺ +Bi ³⁺ ] is less than 7%.

Nb ⁵⁺ , Ti ⁴⁺ , W ⁶⁺ , Ta ⁵⁺ and Bi ³⁺ are components having an effect of increasing the refractive index, and by appropriately containing them, they also have an effect of improving the thermal stability of the glass. In addition, when the content of these components increases, the Abbe number (νd) decreases. Therefore, these components are called high refractive index and high dispersion components. Therefore, when the total content (HR) of such components is too large, the Abbe number (νd) decreases, making it difficult to achieve desired optical characteristics. Therefore, in the optical glass of the present embodiment, in order to achieve desired optical characteristics, the total content (HR) is set within the above range.

Further, in the optical glass of the present embodiment, the content of Nb ⁵⁺ with respect to the total content of Nb ⁵⁺ and Ta ⁵⁺ proportion, i.e., the cation ratio ^{(γ) = [Nb 5+ /} (Nb 5+ + Ta 5 ⁺ )] is 0.5 or more.

The main object of the present invention is to provide an optical glass having excellent thermal stability and required optical characteristics (refractive index (nd) and Abbe number (νd)) while reducing the content of Ta ⁵⁺ . Therefore, in order to maintain the optical characteristics and thermal stability in a good state, the present inventors conducted research on optical glasses containing high refractive index and high dispersion components other than Ta ⁵⁺ .

Among the high-refractive-index and high-dispersion components, Ti ⁴⁺ and W ⁶⁺ easily react with the molding surface of the press-molding mold during precision press molding. Therefore, in the optical glass after press molding, there is a decrease in the transparency of the glass surface (Or cloudy), the risk of bubbles (foaming) on the glass surface. In addition, W ⁶⁺ and Bi ³⁺ tend to increase the coloration of glass.

Therefore, the optical glass of this embodiment contains Nb ^{5+ in} order to provide glass for manufacturing an optical element with less coloration and good surface quality. Moreover, the content is determined by the relationship with Ta ⁵⁺ based on the above cation ratio (γ).

Compared with Ta ⁵⁺ , Nb ⁵⁺ is a component that has a greater effect of improving the meltability of glass and has a thermal stability-improving effect, although not as good as Ta ⁵⁺ . In addition, Nb ⁵⁺ is easier to obtain raw materials than Ta ⁵⁺ , and the raw material cost is also low. Therefore, when the content of Nb ⁵⁺ is less than that of Ta ⁵⁺ (cation ratio (γ) is less than 0.5), it is difficult to stably supply low-cost and stable optical stability while maintaining the desired optical state Characteristics and good melting glass. Therefore, in the optical glass of the present embodiment, in order to stably produce glass having good thermal stability and required optical characteristics, the cation ratio (γ) is set within the above range.

In addition, in the optical glass of this embodiment, the sum of 6 times the content of Li ⁺ and 2 times the content of Zn ²⁺ minus the content of Si ⁴⁺ (L)=[(6×Li ⁺ )+ (2×Zn ²⁺ )-Si ⁴⁺ ] is 24 or more. The meaning of the prescribed value (L) is as follows.

Among the cationic components, Li ⁺ is a component having a large effect of lowering the glass transition temperature (Tg). In addition, Zn ²⁺ has the effect of lowering the glass transition temperature (Tg) while maintaining the refractive index (nd). In addition, Si ⁴⁺ is a component having an effect of increasing the glass transition temperature (Tg).

Based on this knowledge, the inventors conducted intensive research and found that the above-mentioned components can be vitrified by the above value (L)=[(6×Li ⁺ )+(2×Zn ²⁺ )-Si ⁴⁺ ] The magnitude of the relative influence of the transition temperature (Tg) is quantified.

That is, when the total content of all cationic components is set to 100% (converted in cation %), the above value (L) can be a value that is 6 times the content of Li ⁺ and 2 times the content of Zn ²⁺ The total value of the value and the value of -1 times the Si ⁴⁺ content [(6×Li ⁺ )+(2×Zn ²⁺ )-Si ⁴⁺ ] is exported. The value (L) becomes the benchmark of the low-temperature softening property of glass.

FIG. 1 is a graph plotted for a well-known glass with the horizontal axis as the value (L) and the vertical axis as the glass transition temperature (Tg). It can be clearly seen from Fig. 1 that there is a correlation between the value (L) and Tg.

In this way, by increasing the value (L) to 24 or more, it is possible to obtain a glass that reduces Tg and is suitable for precision press molding, that is, an optical glass having low-temperature softening can be obtained. In addition, by increasing the value (L), the meltability of the glass can also be improved, that is, there is no melting residue of the glass raw material, and it is easy to produce a homogeneous glass.

In addition, by improving the meltability of the glass, a better improvement effect can be expected for the transmittance and clarity of the visible light region of the glass. details as follows.

First, the effect of improved meltability on the transmittance in the visible light region will be described.

In general, when the meltability of glass is poor, the melting residue of the glass raw material becomes a problem. Such melting residue will cause the glass composition to change, resulting in poor glass uniformity. Therefore, it is common to raise the melting temperature and extend the melting time to manufacture glass so that there is no melting residue of the glass raw material.

However, although raising the melting temperature and extending the melting time can eliminate the problem of residual melting of the glass raw material, it causes new problems such as deterioration of the melting vessel and increase in production cost. In particular, the erosion of the molten container by the molten glass becomes a big problem.

In general, when melting glass that requires high homogeneity like optical glass, precious metal crucibles such as platinum crucibles are widely used as melting vessels. Compared with crucibles made of other materials, noble metal crucibles are less susceptible to corrosion by molten glass. However, as described above, in the case of manufacturing glass with poor melting properties, high-temperature molten glass will be in contact with the crucible for a long time, so even a crucible made of precious metals will be eroded by the molten glass.

For example, in the case of a platinum crucible, the platinum constituting the crucible may be mixed into the molten glass as a solid substance due to corrosion of the molten glass. Such a solid substance becomes an impurity in the optical glass and becomes a light scattering source. In addition, when the crucible is slightly eroded to dissolve platinum as ions into the molten glass, the color absorption of the optical glass becomes stronger due to the light absorption of platinum ions, and the transmittance in the visible light region decreases.

On the other hand, if it is glass with excellent meltability, the problem of residual melting of glass raw materials is unlikely to occur. Therefore, it is possible to suppress the erosion of the molten container by the molten glass without increasing the melting temperature and extending the melting time. Furthermore, it is possible to suppress the decrease in the transmittance of glass due to the extension of the melting time.

That is, by improving the meltability, the homogeneity of the glass can be improved, and the decrease in transmittance in the visible light region can be suppressed.

Next, the effect of improving meltability on clarity will be described.

Usually, the batch of raw materials (raw materials prepared with multiple compounds) Rough melt (rough melt) to produce cullet raw material, remelt (mellt) to produce optical glass method (coarse melting-remelting method), in the remelting of molten glass to improve the defoaming (ie , To improve clarification), it is preferable that the broken glass contains many gas components, that is, it is preferable that the amount of gas components dissolved in the molten glass before clarification is high.

Here, the gas component is, for example, moisture, CO _x , NO _x, and SO _x that are generated by heating and decomposing boric acid, carbonate, nitrate, sulfate, and hydroxide contained in the batch material.

As described above, when manufacturing a glass with poor meltability, it is necessary to raise the melting temperature and extend the melting time to manufacture the glass so that no melting residue of the glass raw material occurs. In particular, when the melting temperature of the raw material of the coarsely melted batch material is increased, the gas from the raw material is easily released from the melt of the raw material of the batch material, and further, when the time of the rough melting is prolonged, a sufficient amount does not remain in the broken glass Gas composition.

Generally, by remelting broken glass, the gas components remaining in the broken glass become bubbles in the molten glass, and the tiny bubbles gather together to become large bubbles, and the speed of floating in the molten glass increases, in a short time Discharged out of molten glass. However, when the glass has poor meltability as described above, a sufficient amount of gas components will not remain in the broken glass, so it is difficult to generate large bubbles that can float up with tiny bubbles, and it is difficult for the tiny bubbles to be discharged into the molten glass outer. Therefore, sufficient clarification cannot be performed, resulting in a problem that minute bubbles remain in the optical glass.

On the other hand, in the rough melting of glass with excellent meltability, the batch raw material can be melted at a relatively low temperature. Therefore, it is possible to produce broken glass in a state in which a gas component is dissolved in the melt. By remelting broken glass, from The gas components remaining in the broken glass become bubbles in the molten glass, and tiny bubbles gather together and float up to be discharged out of the molten glass, so that the bubbles can be efficiently removed. As a result, the glass can be clarified in a relatively short time.

That is, by improving the meltability, the clarity of the glass can be improved, and the throughput of glass per unit time can be increased.

As explained above, by improving the meltability, the transmittance and clarity of the visible light region of the glass can also be improved. In addition, by improving the meltability, the energy consumed by the melting of the glass can be reduced, and the melting time can also be shortened. Therefore, it is also possible to expect a reduction in production cost and an improvement in productivity. It can be said that it is very beneficial to improve the meltability.

As described above, the value (L)=[6×Li ⁺ +2×Zn ²⁺ -Si ⁴⁺ ] determined in this embodiment is an index of low-temperature softening, and is also an effective index for improving the meltability. . Therefore, in the optical glass of the present embodiment, in order to obtain low-temperature softening suitable for precision press molding and improve the meltability of the glass, the value (L)=[6×Li ⁺ +2×Zn ²⁺ -Si ⁴⁺ ] is 24 or more. In addition, the value (L) is a number obtained by multiplying the content of the above-mentioned three components as a coefficient and multiplying the degree of influence of each component on the glass transition temperature, so it has no unit.

Furthermore, in the optical glass of this embodiment, the Abbe number (νd) is 43.5 to 47. When the Abbe number (νd) is 43.5 or more, the material as an optical element is effective for correcting chromatic aberration. In addition, when the Abbe number (νd) is greater than 47, if the refractive index (nd) is not decreased, the thermal stability of the glass significantly decreases, and devitrification is likely to occur during the manufacturing process of the glass. Therefore, in the optical glass of the present embodiment, in order to maintain the thermal stability in a good state and achieve effective optical characteristics as a material of the optical element, the range of the Abbe number (νd) is set to the above range.

In addition, in the optical glass of the present embodiment, the refractive index (nd) satisfies the following formula (1) with respect to the Abbe number (νd).

The refractive index (nd) with respect to the Abbe number (νd) is within the range determined by the above formula (1), whereby an optical glass with high utilization value in optical design can be obtained. In addition, when the refractive index (nd) is excessively increased, the thermal stability tends to decrease. Therefore, in the optical glass of the present embodiment, in order to achieve effective optical characteristics as a material of the optical element while maintaining thermal stability in a good state, the range of the refractive index (nd) is set to the above range.

As described above, the optical glass of the present embodiment has the characteristics described above, and can provide a high refractive index and low dispersion glass with excellent thermal stability and low-temperature softening while reducing the content of Ta ⁵⁺ .

<glass composition>

Hereinafter, the glass composition will be described in detail. In addition, unless otherwise specified, the contents of various constituent components and the like are expressed as cation% or anion %. The optical glass of this embodiment is an oxide glass, and by determining the content ratio of the cation component, the glass composition can be determined.

The optical glass of this embodiment preferably contains B ³⁺ , La ³ , any one or more selected from Gd ³⁺ , Y ³⁺ and Yb ³⁺ , Nb ⁵⁺ , selected from Li ⁺ and Zn ²⁺ Any one or more.

In the optical glass of this embodiment, the total content of B ³⁺ , Si ⁴⁺ , La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ [B ³⁺ +Si ⁴⁺ +La ³⁺ +Gd ^{3 +} +Y ³⁺ +Yb ³⁺ ] is 65% or more. By making the total content [B ³⁺ +Si ⁴⁺ +La ³⁺ +Gd ³⁺ +Y ³⁺ +Yb ³⁺ ] into the above range, the thermal stability can be maintained while maintaining a good state. The required refractive index (nd) and Abbe number (νd).

The upper limit of the total content [B ³⁺ +Si ⁴⁺ +La ³⁺ +Gd ³⁺ +Y ³⁺ +Yb ³⁺ ] is preferably 90%, and further preferably 88.0%, 86.0%, and 84.0%. In addition, the lower limit of the total content [B ³⁺ +Si ⁴⁺ +La ³⁺ +Gd ³⁺ +Y ³⁺ +Yb ³⁺ ] is 65%, preferably 68.0%, and further preferably 70.0%, 72.0 %, 74.0%.

By satisfying the upper limit of the total content [B ³⁺ +Si ⁴⁺ +La ³⁺ +Gd ³⁺ +Y ³⁺ +Yb ³⁺ ], the glass transition temperature (Tg) can be maintained The glass has a low refractive index (nd) and Abbe number (νd) while maintaining thermal stability in a good state. In addition, the lower limit of the total content [B ³⁺ +Si ⁴⁺ +La ³⁺ +Gd ³⁺ +Y ³⁺ +Yb ³⁺ ] satisfies the above-mentioned preferred value, so that the thermal stability of the glass can be maintained A glass in good condition with the desired refractive index (nd) and Abbe number (νd).

In the optical glass of this embodiment, the upper limit of the total content of B ³⁺ , Si ⁴⁺ and Al ³⁺ (NWF) = [B ³⁺ +Si ⁴⁺ +Al ³⁺ ] is preferably 62%, and in turn More preferably, they are 61.0% and 58.0%. In addition, the lower limit of the total content (NWF) is preferably 40%, and further preferably 42.0%, 44.0%, 46.0%, 48.0%, 50.0%, 52.0%, and 54.0%.

B ³⁺ , Si ⁴⁺ and Al ³⁺ are network forming components of glass, and the content ratio of these components affects the devitrification resistance, glass transition temperature (Tg), meltability, moldability, etc. of the glass. When the lower limit of the total content (NWF) is the above value, the thermal stability of the glass can be maintained in a good state, and crystallization (precipitation of crystals) of the glass during the manufacturing process can be suppressed. That is, it is possible to improve the devitrification resistance of glass and suppress the increase in liquidus temperature.

Generally, when the liquidus temperature rises, in order to prevent devitrification of glass during melting, it is necessary to increase the melting temperature. When the melting temperature is increased, the coloration of the glass will increase, and the amount of volatilization of the glass components during the melting process will increase, easily causing a change in composition. As a result, the characteristics of the glass, especially the optical characteristics such as refractive index and Abbe number, are greatly changed. Therefore, in order to prevent devitrification at the time of glass manufacturing and suppress the coloring and composition change of the glass, and to stabilize the characteristics of the glass, it is also desired to improve the thermal stability of the glass and suppress the increase in liquidus temperature.

In addition, in the optical glass of this embodiment, the total content (RE) of La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ = [La ³⁺ +Gd ³⁺ +Y ³⁺ +Yb ³⁺ ] The upper limit of is preferably 34%, and further preferably 32.0%, 28.0%, 27.0%, 26.0%, and 25.0%. In addition, the lower limit of the total content (RE) is preferably 16%, and further preferably 18.0%, 20.0%, 21.0%, and 22.0% in this order.

La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ are rare earth components that have the effect of increasing the refractive index while suppressing the decrease in Abbe number (νd). In addition, these components can improve the chemical durability and weather resistance of the glass, but also have the effect of increasing the glass transition temperature (Tg). Therefore, when the total content (RE) increases, the thermal stability of the glass tends to decrease, and the glass transition temperature (Tg) tends to increase. In addition, when the glass is melted, the glass raw material is likely to remain molten. On the other hand, when the total content (RE) decreases, the refractive index (nd) decreases, the Abbe number (νd) decreases, and the chemical durability tends to decrease. Therefore, in order to maintain the thermal stability and meltability of glass and suppress the increase in glass transition temperature (Tg) while suppressing the decrease in refractive index (nd) and Abbe number (νd) and maintaining chemical durability, The total content (RE) is within the above range.

In the optical glass of the present embodiment, the total content (RE) of La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ relative to the total content (NWF) of B ³⁺ , Si ⁴⁺ and Al ³⁺ The ratio, that is, the cation ratio (α)=[RE/NWF] is 0.30 to 0.70. By satisfying the above range, the desired refractive index (nd) and Abbe number (νd) can be achieved while maintaining thermal stability in a good state.

The upper limit of the cation ratio (α) is 0.70, preferably 0.60, and more preferably 0.50, 0.45, 0.44, and 0.43 in this order. The lower limit of the cation ratio (α) is 0.30, preferably 0.32, and further preferably 0.34, 0.36, 0.37, 0.38, and 0.39 in this order.

In addition, in the optical glass of the present embodiment, the upper limit of the content of B ³⁺ is preferably 62%, and in turn, more preferably 60.0%, 58.0%, and 57.0%. In addition, the lower limit of the content of B ³⁺ is preferably 40%, and further preferably 42.0%, 44.0%, 46.0%, 48.0%, 50.0%, and 51.0%.

B ^{3+ is} better than Si ⁴⁺ and Al ^{3+ in} improving the meltability and lowering the glass transition temperature (Tg). When the content of B ³⁺ is small, the thermal stability and meltability of the glass tend to decrease. On the other hand, when the content of B ^{3+ is} large, the refractive index (nd) and chemical durability tend to decrease. Therefore, in order to improve the devitrification resistance, meltability, moldability, etc. of the glass and maintain the refractive index (nd) and Abbe number (νd) within the range of the above formula (1), the content of B ³⁺ is preferably The above range.

In addition, in the optical glass of the present embodiment, the upper limit of the content of Si ⁴⁺ is preferably 10%, and further preferably 8.0%, 7.0%, 6.0%, and 5.0% in this order. In addition, the lower limit of the content of Si ⁴⁺ is preferably 0%, and further preferably 0.1%, 0.2%, 0.3%, 0.4%, and 0.5%.

Si ⁴⁺ has the effects of improving the chemical durability and weather resistance of glass, and increasing the viscosity of glass during melting. When the content of Si ⁴⁺ is small, the thermal stability and chemical durability of the glass tend to decrease. On the other hand, when the content of Si ^{4+ is} large, the thermal stability and low-temperature softening of the glass tend to decrease. Therefore, in order to improve the devitrification resistance, meltability, moldability, low-temperature softening, etc. of the glass, the content of Si ⁴⁺ is preferably within the above range.

In addition, in the optical glass of the present embodiment, the upper limit of the content of Al ³⁺ is preferably 10%, and further preferably 8.0%, 7.0%, 5.0%, 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 Al ³⁺ is preferably 0%. In addition, the content of Al ³⁺ may be 0%.

Al ³⁺ is a component that has the effect of improving the chemical durability and weather resistance of glass. However, when the content of Al ³⁺ increases, problems such as a decrease in refractive index (nd), a decrease in the thermal stability of the glass, an increase in the glass transition temperature (Tg), and a decrease in meltability are likely to occur. In order to avoid such a problem, the content of Al ³⁺ is preferably within the above range.

Further, in the optical glass of the present embodiment aspect, with respect to the content of B ³⁺ B ^3+, the ratio of the total content (NWF) of Si ⁴⁺ and Al ^3+, i.e. the upper limit of the cation ratio of [B ³⁺ / NWF] of It is preferably 1, and further preferably 0.99, 0.97, 0.96, 0.95 in this order. In addition, the lower limit of the cation ratio [B ³⁺ /NWF] is preferably 0.5, and further preferably 0.60, 0.68, 0.70, 0.76, 0.77, 0.80, 0.85, 0.90, 0.91, 0.92.

When the cation ratio [B ³⁺ /NWF] is small, the meltability of the glass decreases and the glass transition temperature (Tg) tends to increase. In addition, although the cation ratio [B ³⁺ /NWF] can also be set to 1, by containing a small amount of Si ⁴⁺ , it is easy to change the viscosity of the glass during molding to a viscosity suitable for molding. Therefore, in order to improve the moldability while maintaining good meltability and low-temperature softening of glass, the upper limit of [B ³⁺ /NWF] is preferably within the above range.

In addition, in the optical glass of this embodiment, La ³⁺ is an essential component. La ³⁺ is a component that is difficult to reduce the thermal stability and meltability of glass even if it is contained in a large amount. The upper limit of the content of La ³⁺ is preferably 25%, and further preferably 23%, 22%, 21%, and 20%. In addition, the lower limit of the content of La ³⁺ is preferably 5%, and further preferably 7%, 8%, 9%, and 10%.

In addition, in the optical glass of the present embodiment, the upper limit of the content of Gd ³⁺ is preferably 20%, and further preferably 18.0%, 16.0%, 15.0%, and 14.0% in this order. In addition, the lower limit of the content of Gd ³⁺ is preferably 0%, and further preferably 0.1%, 0.5%, 1.0%, and 2.0% in this order.

In addition, in the optical glass of the present embodiment, the upper limit of the content of Y ³⁺ is preferably 15%, and further preferably 12.0%, 10.0%, 9.0%, 8.0%, 6.0%, 5.0%, 4.0%. In addition, the lower limit of the content of Y ³⁺ is preferably 0%, and further preferably 0.1%, 0.5%, and 1.0% in this order.

In addition, in the optical glass of the present embodiment, the upper limit of the content of Yb ³⁺ is preferably 5%, and further preferably 4.0%, 3.0%, 2.0%, 1.5%, 1.0%, 0.5%, 0.2%, 0.1%, 0.05%, 0.01%. In addition, the lower limit of the content of Yb ³⁺ is preferably 0%. In addition, the content of Yb ³⁺ may be 0%.

In the optical glass of the present embodiment aspect, with respect to the content of La ³⁺ La ^3+, the ratio of Gd ^3+, Y ³⁺ and Yb ³⁺ total content (RE), i.e., the cation ratio of (β) = [La ^{3 +} /RE] Less than 1 and does not contain 0. By setting the cation ratio (β) within the above range, the thermal stability and meltability can be maintained well.

When the cation ratio (β) is less than 1, the upper limit is preferably 0.95, and further preferably 0.90, 0.85, 0.84, 0.83, and 0.82. In addition, the lower limit of the cation ratio (β) is preferably 0.2, and further preferably 0.3, 0.35, 0.4, 0.41, 0.42, 0.43, and 0.44 in this order. When the contents of Gd ³⁺ , Y ³⁺ and Yb ³⁺ are too small, the thermal stability of the glass tends to decrease. In addition, when the respective contents of Gd ³⁺ , Y ³⁺ and Yb ³⁺ are too large, the thermal stability and meltability of the glass tend to decrease.

Further, the optical glass of the present embodiment, Gd ^3+, and Y ³⁺ to the total content of La ^3+, the ratio of Gd ^3+, Y ³⁺ and Yb ³⁺ total content (RE), i.e. the cation ratio The upper limit of [(Gd ³⁺ +Y ³⁺ )/RE] is preferably 0.8, and further preferably 0.7, 0.65, 0.6, 0.59, 0.58, 0.57, 0.56 in this order. In addition, the cation ratio [(Gd ³⁺ +Y ³⁺ )/RE] preferably exceeds 0, and the lower limit thereof is more preferably 0.05, 0.1, 0.15, 0.16, 0.17, 0.18, 0.19.

In La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ , the atomic weight of Yb ³⁺ is large, which will increase the specific gravity of the glass, but the effect of increasing the refractive index is small. However, the optical power (refractive power) of the lens is determined by the refractive index of the material constituting the lens and the curvature of the lens surface (optical functional surface of the lens). Therefore, in a lens having a fixed power, the higher the refractive index of the lens material, the smaller the absolute value of the curvature of the lens surface, and the thinner the thickness of the lens. Therefore, in order to reduce the weight of the lens, it is effective to use glass with a high refractive index and a small specific gravity. On the contrary, when the refractive index of the glass cannot be sufficiently increased or the increase in specific gravity cannot be suppressed, the weight of the optical element increases. For example, if a heavy single lens is incorporated into an autofocus imaging lens, the power required to drive the lens during autofocus will increase, and the battery consumption will increase. Compared with La ³⁺ , Gd ³⁺ and Y ³⁺ , Yb ³⁺ not only has a poor effect of increasing the refractive index, but also has a poor effect of suppressing the increase in specific gravity. Therefore, it is desirable to reduce the content of Yb ³⁺ and suppress the increase in the specific gravity of the optical element. In addition, Yb ³⁺ absorbs near infrared. Therefore, glass with a large content of Yb ³⁺ has strong absorption of light in the near-infrared region, and it is not preferable as a glass material for optical components used in optical systems that require near-infrared light transmission, such as surveillance cameras and night vision cameras. .

In addition, Gd ³⁺ and Y ³⁺ coexist with La ³⁺ in the glass, thereby greatly improving the thermal stability of the glass. Therefore, in order to obtain a glass that maintains good thermal stability without adversely affecting the transmission of near-infrared rays and has desired optical characteristics, the cation ratio [(Gd ³⁺ +Y ³⁺ )/RE] is relatively high The above range is preferable.

In the optical glass of this embodiment, the total content of Nb ⁵⁺ , Ti ⁴⁺ , W ⁶⁺ , Ta ⁵⁺ and Bi ³⁺ HR=[Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Ta ⁵⁺ + Bi ³⁺ ] is less than 7%. By setting the total content (HR) to the above range, the decrease in Abbe number (νd) can be suppressed while maintaining the thermal stability of the glass, and the desired optical characteristics can be achieved.

The total content (HR) is less than 7%, and the upper limit is preferably 6.0%, and further preferably 5.0% and 4.0%. In addition, the lower limit of the total content (HR) is preferably 0%, and further preferably 0.1%, 0.5%, 1.0%, 1.5%, and 2.0%.

In the optical glass of the present embodiment aspect, with respect to the content of Nb ⁵⁺ and Ta, the ratio of the total content of Nb ^{5+ 5+,} i.e., the cation ratio ^{(γ) = [Nb 5+ /} (Nb 5+ + Ta 5+) ] Is 0.5 or more. By setting the cation ratio (γ) to the above range, it is possible to stably manufacture glass having good thermal stability and desired optical characteristics.

Furthermore, in the optical glass of the present embodiment, the upper limit of the cation ratio (γ) is preferably 1. In addition, the lower limit of the cation ratio (γ) is 0.5, preferably 0.6, and further preferably 0.70, 0.80, 0.90, 0.95, 0.98 in this order. In addition, the cation ratio (γ) may be 1.

In addition, in the optical glass of the present embodiment, the total content of Nb ⁵⁺ , Ti ⁴⁺ and W ⁶⁺ is relative to the total content of Nb ⁵⁺ , Ti ⁴⁺ , W ⁶⁺ , Ta ⁵⁺ and Bi ³⁺ ( The upper limit of the ratio of HR), that is, the cation ratio [(Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ )/HR] is preferably 1. In addition, the lower limit of the cation ratio [(Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ )/HR] is preferably 0.5, and further preferably 0.60, 0.70, 0.80, 0.90, 0.95 in this order. In addition, the cation ratio [(Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ )/HR] may be 1. Among the components of the high refractive index and high dispersion, Ta ⁵⁺ foregoing reasons, Bi ³⁺ is due to the large atomic weight and will increase the specific gravity of glass and colored glass component is increased, and therefore preferred to reduce these components content.

In addition, in the optical glass of this embodiment, the total content of Nb ⁵⁺ , Ti ⁴⁺ and W ⁶⁺ [Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ ] is preferably less than 7%, and the upper limit is more preferably 6.0%, 5.0%, 4.0%. In addition, the total content [Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ ] preferably exceeds 0, and the lower limit thereof is more preferably 0.1%, 0.5%, 1.0%, 1.5%, 2.0%. By setting the total content [Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ ] to the above range, the effects and effects of the high refractive index and high dispersion component can be obtained while reducing the content of Ta ⁵⁺ and Bi ³⁺ .

Further, in the optical glass of the present embodiment, the Nb ⁵⁺ content relative to the total content of Nb ^5+, Ta ^5+, and W ⁶⁺ proportion, i.e., cationic ⁵⁺ + Ta ratio [Nb ⁵⁺ / (Nb ^{5 +} +W ⁶⁺ )] The upper limit is preferably 1. In addition, the lower limit of the cation ratio [Nb ⁵⁺ /(Nb ⁵⁺ +Ta ⁵⁺ +W ⁶⁺ )] is preferably 0.3, and further preferably 0.40, 0.50, 0.55, 0.60, 0.70, 0.80, 0.90 in this order. In addition, the cation ratio [Nb ⁵⁺ /(Nb ⁵⁺ +Ta ⁵⁺ +W ⁶⁺ )] may be 1. By setting the cation ratio [Nb ⁵⁺ /(Nb ⁵⁺ +Ta ⁵⁺ +W ⁶⁺ )] to the above range, it is possible to obtain a glass with less coloration and excellent thermal stability while reducing the content of Ta ⁵⁺ .

Further, in the optical glass of the present embodiment, the content of Nb ⁵⁺ with respect to the total content of Nb ^5+, and W ⁶⁺ ratio, i.e., the cation ratio ^{[Nb 5+ / (Nb 5+ +} W 6+)] of The upper limit is preferably 1. In addition, the lower limit of the cation ratio [Nb ⁵⁺ /(Nb ⁵⁺ +W ⁶⁺ )] is preferably 0.3, and further preferably 0.40, 0.50, 0.60, 0.68, 0.70, 0.80, 0.84, 0.86, 0.88, 0.90 , 0.95. In addition, the cation ratio [Nb ⁵⁺ /(Nb ⁵⁺ +W ⁶⁺ )] may be 1. By setting the cation ratio [Nb ⁵⁺ /(Nb ⁵⁺ +W ⁶⁺ )] to the above range, it is possible to obtain a glass with less coloring while maintaining good thermal stability.

In addition, in the optical glass of this embodiment, the total content of Ti ⁴⁺ , W ⁶⁺ and Bi ³⁺ [Ti ⁴⁺ +W ⁶⁺ +Bi ³⁺ ] is preferably less than 4.25%, and the upper limit thereof is more preferably 4.0%, 3.5%, 3.0%, 2.5%, 2.0%, 1.5%, 1.0%, 0.5%, 0.2%, 0.1%. In addition, the lower limit of the total content [Ti ⁴⁺ +W ⁶⁺ +Bi ³⁺ ] is preferably 0%. In addition, the total content [Ti ⁴⁺ +W ⁶⁺ +Bi ³⁺ ] may be 0%.

When the total content [Ti ⁴⁺ +W ⁶⁺ +Bi ³⁺ ] increases, the following defects occur, that is, the coloring of the glass increases, and the glass reacts with the press-forming mold during precision press molding to make the glass The surface quality is degraded, and it is easy to cause fusion of glass and press molding molds. Therefore, in order to suppress the large decrease in Abbe number (νd) and the coloring of the glass while maintaining the surface quality of the glass during precision press molding, and to prevent fusion between the glass and the press mold, the total content is preferably [Ti ³⁺ +W ⁶⁺ +Bi ³⁺ ] is the above range.

In the optical glass of this embodiment, Nb ⁵⁺ is an essential component. The content of Nb ⁵⁺ is preferably less than 7%, and the upper limit is more preferably 6.0%, 5.5%, 5.0%, and 4.0%. In addition, the lower limit of the content of Nb ⁵⁺ is preferably 0.1%, and further preferably 0.5%, 0.8%, 1.0%, 1.1%, and 1.5%.

In the optical glass of the present embodiment, the content of Ti ⁴⁺ is preferably less than 4.25%, and the upper limit thereof is more preferably 4.0%, 3.0%, 2.5%, 2.0%, 1.5%, 1.0%, 0.5%, 0.1%. In addition, the lower limit of the content of Ti ⁴⁺ is preferably 0%. In addition, the content of Ti ⁴⁺ may be 0%.

In the optical glass of this embodiment, the content of W ⁶⁺ is preferably less than 4.25%, and the upper limit thereof is more preferably 4.0%, 3.0%, 2.5%, 2.0%, 1.5%, 1.2%, and 1.0%. In addition, the lower limit of the content of W ⁶⁺ is preferably 0%. In addition, the content of W ⁶⁺ may be 0%.

In the optical glass of this embodiment, the upper limit of the content of Ta ⁵⁺ is preferably 5%, and further preferably 4.0%, 3.0%, 2.0%, 1.5%, 1.0%, 0.55%, and 0.1%. In addition, the lower limit of the content of Ta ⁵⁺ is preferably 0%. In addition, the content of Ta ⁵⁺ may be 0%.

In the optical glass of this embodiment, the content of Bi ³⁺ is preferably less than 4.25%, and the upper limit thereof is more preferably 4.0%, 3.0%, 2.0%, 1.5%, 1.0%, 0.55%, and 0.1%. In addition, the lower limit of the content of Bi ³⁺ is preferably 0%. In addition, the content of Bi ³⁺ may be 0%.

In addition, in the optical glass of this embodiment, the total content (RE) of La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ is relative to Nb ⁵⁺ , Ti ⁴⁺ , W ⁶⁺ , Ta ⁵⁺ and The ratio of the total content (HR) of Bi ³⁺ , that is, the upper limit of the cation ratio [RE/HR] is preferably 21, and further preferably 19.0, 17.0, 15.0, 13.0, 12.0, and 11.0 in this order. In addition, the lower limit of the cation ratio [RE/HR] is preferably 1, and further preferably 2.0, 3.0, 4.0, 5.0, 6.0, 7.0 in this order.

When the cation ratio [RE/HR] decreases, the Abbe number (νd) tends to decrease. On the other hand, when the cation ratio [RE/HR] increases, it shows vitrification The transition temperature (Tg) tends to increase, and the thermal stability of the glass tends to decrease. Therefore, in order to achieve desired optical characteristics, the preferred cation ratio [RE/HR] is within the above range.

In addition, in the optical glass of the present embodiment, the total content (HR) of Nb ⁵⁺ , Ti ⁴⁺ , W ⁶⁺ , Ta ⁵⁺ and Bi ³⁺ relative to those of B ³⁺ , Si ⁴⁺ and Al ³⁺ The ratio of the total content (NWF), that is, the upper limit of the cation ratio [HR/NWF] is preferably 0.5, and further preferably 0.30, 0.20, 0.10, 0.08, 0.07, and 0.06. The lower limit of the cation ratio [HR/NWF] is preferably 0.01, and further preferably 0.02, 0.03, 0.04, and 0.05 in this order.

When the cation ratio [HR/NWF] decreases, the refractive index (nd) decreases and the thermal stability of the glass tends to improve. In addition, when the cation ratio [HR/NWF] increases, the Abbe number (νd) decreases and the thermal stability of the glass tends to decrease. Therefore, in order to obtain an optical glass that maintains the thermal stability of the glass in a good state and has desired optical characteristics, the cation ratio [HR/NWF] is preferably in the above range.

In the optical glass of this embodiment, the sum of 6 times the content of Li ⁺ and 2 times the content of Zn ²⁺ minus the content of Si ⁴⁺ (L)=[(6×Li ⁺ )+(2 ×Zn ²⁺ )-Si ⁴⁺ ] is 24 or more. By setting the value (L) to the above range, low-temperature softening suitable for precision press molding can be obtained, and the meltability of the glass can be improved.

The upper limit of the value (L) is preferably 45, and further preferably 44.0 and 43.0 in this order. In addition, the lower limit of the value (L) is 24, and it is preferably 24.5, 25.0, 25.5, 26.5, and 27.5 in this order.

In addition, in the optical glass of the present embodiment, in order to lower the glass transition temperature (Tg), the total value of 6 times the content of Li ⁺ and twice the value of Zn ²⁺ content [(6×Li ⁺ )+(2×Zn ²⁺ )] preferably satisfies the following range. The upper limit of the value [(6×Li ⁺ )+(2×Zn ²⁺ )] is preferably 45, and further preferably 44.0, 43.0, 42.0, 40.0, and 38.0 in this order. In addition, the lower limit of the value [(6×Li ⁺ )+(2×Zn ²⁺ )] is preferably 24, and further preferably 24.5, 25.0, and 26.0 in this order.

In addition, the optical glass of the present embodiment preferably contains at least Zn ²⁺ .

In the optical glass of the present embodiment, the upper limit of the content of Zn ²⁺ is preferably 25%, and further preferably 22.0%, 20.0%, 18.0%, 17.0%, and 16.0%. In addition, the lower limit of the content of Zn ²⁺ is preferably 5%, and further preferably 8.0%, 9.0%, 10.0%, and 11.0% in this order.

Zn ²⁺ is a component having an effect of lowering the glass transition temperature (Tg) while maintaining the refractive index, and an effect of promoting the melting of the raw material of the glass (that is, an effect of improving the meltability) when the glass is melted. In addition, compared with other divalent metal components such as alkaline earth metals, Zn ²⁺ has a strong effect of improving the thermal stability of glass and lowering the liquidus temperature. However, when the content of Zn ²⁺ increases, the Abbe number (νd) decreases, making it difficult to obtain desired optical characteristics. Therefore, in order to maintain desired optical characteristics, lower the glass transition temperature (Tg), and improve the meltability and thermal stability of the glass, the content of Zn ²⁺ is preferably within the above range.

The optical glass of the present embodiment preferably contains any one or more selected from Li ⁺ , Na ⁺ and K ⁺ .

In the optical glass of this embodiment, the upper limit of the content of Li ⁺ is preferably 10%, and further preferably 8.0%, 6.0%, 5.0%, 4.0%, 3.5%, 3.0%, 2.5%, and 2.0%. In addition, the lower limit of the content of Li ⁺ is preferably 0%, and further preferably 0.1%, 0.3%, 0.5%, and 1.0%.

Li ⁺ is a component that has a strong effect of lowering the glass transition temperature (Tg) and is useful for obtaining low-temperature softening. In addition, Li ⁺ also plays a role in improving the meltability of the glass. In addition, when the content of Li ⁺ increases, the refractive index (nd) tends to decrease. Therefore, in order to maintain the required optical characteristics and reduce the glass transition temperature (Tg), the content of Li ⁺ is preferably in the above range.

In the optical glass of this embodiment, the upper limit of the content of Na ⁺ is preferably 5%, and further preferably 4.0%, 3.0%, 2.0%, 1.0%, 0.5%, and 0.1%. In addition, the lower limit of the content of Na ⁺ is preferably 0%. In addition, the content of Na ⁺ may be 0%.

In the optical glass of this embodiment, the upper limit of the content of K ⁺ is preferably 5%, and further preferably 4.0%, 3.0%, 2.0%, 1.0%, 0.5%, and 0.1% in this order. In addition, the lower limit of the content of K ⁺ is preferably 0%. In addition, the content of K ⁺ may be 0%.

In addition, in the optical glass of the present embodiment, the upper limit of the total content [Li ⁺ +Na ⁺ +K ⁺ ] of Li ⁺ , Na ⁺ and K ⁺ is preferably 10%, and further preferably 8.0% and 6.0% in order. , 5.0%, 4%, 3.5%, 3.0%, 2.5%, 2.0%. In addition, the lower limit of the total content [Li ⁺ +Na ⁺ +K ⁺ ] is preferably 0%, and further preferably 0.1%, 0.3%, 0.5%, and 1.0%.

Both Na ⁺ and K ⁺ have the effect of improving the meltability of the glass, but when their content increases, the refractive index (nd), the thermal stability of the glass, the chemical durability, and the weather resistance decrease. Therefore, the respective contents of Na ⁺ and K ⁺ are preferably within the above ranges.

In addition, the optical glass of this embodiment may contain any one or more types of Rb ⁺ and Cs ⁺ .

In the optical glass of this embodiment, the upper limit of the content of Rb ⁺ is preferably 3%, and further preferably 2.0%, 1.0%, 0.5%, and 0.1% in this order. In addition, the lower limit of the content of Rb ⁺ is preferably 0%. In addition, the content of Rb ⁺ may be 0%.

In the optical glass of this embodiment, the upper limit of the content of Cs ⁺ is preferably 3%, and further preferably 2.0%, 1.0%, 0.5%, and 0.1%. In addition, the lower limit of the content of Cs ⁺ is preferably 0%. In addition, the content of Cs ⁺ may be 0%.

Both Rb ⁺ and Cs ⁺ have the effect of improving the meltability of the glass, but when their content increases, the refractive index (nd), the thermal stability of the glass, the chemical durability, and the weather resistance decrease. Therefore, the respective contents of Rb ⁺ and Cs ⁺ are preferably within the above ranges.

In addition, Rb ⁺ and Cs ⁺ are more expensive components than Li ⁺ , Na ⁺ , and K ⁺ , and are not suitable for general-purpose glass. Therefore, in the optical glass of the present embodiment, the upper limit of the total content of Rb ⁺ and Cs ⁺ [Rb ⁺ +Cs ⁺ ] is preferably 3%, and further preferably 2.0%, 1.0%, 0.5%, 0.2% , 0.1%, 0.05%, 0.01%. In addition, the lower limit of the total content [Rb ⁺ +Cs ⁺ ] is preferably 0%. In addition, the total content [Rb ⁺ +Cs ⁺ ] may be 0%.

The optical glass of this embodiment preferably further contains Zr ⁴⁺ .

In the optical glass of this embodiment, the upper limit of the content of Zr ⁴⁺ is preferably 10%, and further preferably 9.0%, 8.0%, 7.0%, 6.5%, 6.0%, 5.5%, 5.0%, 4.5% . In addition, the lower limit of the content of Zr ⁴⁺ is preferably 0%, and further preferably 0.1%, 0.3%, 0.5%, 0.8%, 1.0%, and 1.5%.

Zr ⁴⁺ is a component that has the effect of increasing the refractive index nd and improving the thermal stability of the glass. However, when the content of Zr ⁴⁺ increases, the thermal stability of the glass decreases, and the glass transition temperature (Tg) rises. In addition, the glass raw material tends to cause melting residue. Therefore, in order to suppress the increase in the glass transition temperature (Tg), maintain the meltability of the glass well, and achieve the desired optical characteristics while improving the thermal stability of the glass, the Zr ⁴⁺ content is preferably within the above range.

The optical glass of this embodiment may further contain the following components as necessary.

In the optical glass of the present embodiment, the upper limit of the content of Mg ²⁺ is preferably 5%, and further preferably 4.0%, 3.5%, 3.0%, 2.5%, 2.0%, 1.0%, 0.5%, 0.1% . In addition, the lower limit of the content of Mg ²⁺ is preferably 0%. In addition, the content of Mg ²⁺ may be 0%.

In the optical glass of this embodiment, the upper limit of the content of Ca ²⁺ is preferably 5%, and further preferably 4.0%, 3.5%, 3.0%, 2.5%, 2.0%, 1.0%, 0.5%, 0.1% . In addition, the lower limit of the content of Ca ²⁺ is preferably 0%. In addition, the content of Ca ²⁺ may be 0%.

In the optical glass of the present embodiment, the upper limit of the content of Sr ²⁺ is preferably 5%, and further preferably 4.0%, 3.5%, 3.0%, 2.5%, 2.0%, 1.0%, 0.5%, 0.1% . In addition, the lower limit of the content of Sr ²⁺ is preferably 0%. In addition, the content of Sr ²⁺ may be 0%.

In the optical glass of the present embodiment, the upper limit of the content of Ba ²⁺ is preferably 5%, and further preferably 4.0%, 3.5%, 3.0%, 2.5%, 2.0%, 1.0%, 0.5%, 0.1% . In addition, the lower limit of the content of Ba ²⁺ is preferably 0%. In addition, the content of Ba ²⁺ may be 0%.

Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ are all components that have an effect of improving the meltability of glass. However, when the content of these components increases, the thermal stability of the glass decreases and it becomes easy to devitrify.

In the optical glass of this embodiment, the upper limit of the total content of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ [Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ ] is preferably 6 %, and in turn, 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 total content [Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ ] is preferably 0%. By making the total content [Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ ] within the above range, the thermal stability of the glass can be maintained in a good state. In addition, the total content [Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ ] may be 0%.

In the optical glass of the present embodiment, the upper limit of the content of Ga ³⁺ is preferably 3%, and further preferably 2.0%, 1.0%, 0.5%, and 0.1% in this order. In addition, the lower limit of the content of Ga ³⁺ is preferably 0%. In addition, the content of Ga ³⁺ may be 0%.

In the optical glass of the present embodiment, the upper limit of the content of In ³⁺ is preferably 3%, and further preferably 2.0%, 1.0%, 0.5%, and 0.1% in this order. In addition, the lower limit of the content of In ³⁺ is preferably 0%. In addition, the content of In ³⁺ may be 0%.

In the optical glass of the present embodiment, the upper limit of the content of Sc ³⁺ is preferably 3%, and further preferably 2.0%, 1.0%, 0.5%, and 0.1% in this order. In addition, the lower limit of the content of Sc ³⁺ is preferably 0%. In addition, the content of Sc ³⁺ may be 0%.

In the optical glass of the present embodiment, the upper limit of the content of Hf ⁴⁺ is preferably 3%, and further preferably 2.0%, 1.0%, 0.5%, 0.1%, 0.05%, and 0.01%. In addition, the lower limit of the content of Hf ⁴⁺ is preferably 0%. In addition, the content of Hf ⁴⁺ may be 0%.

Ga ³⁺ , In ³⁺ , Sc ³⁺ and Hf ⁴⁺ all have the effect of increasing the refractive index (nd). However, these ingredients are expensive and are not necessary to achieve the purpose of the invention. Therefore, it is preferable that the respective contents of Ga ³⁺ , In ³⁺ , Sc ³⁺ , and Hf ⁴⁺ are within the above ranges.

In addition, in the optical glass of this embodiment, the upper limit of the content of Lu ³⁺ is preferably 3%, and further preferably 2.0%, 1.0%, 0.5%, and 0.1% in this order. In addition, the lower limit of the content of Lu ³⁺ is preferably 0%. In addition, the content of Lu ³⁺ may be 0%. Lu ³⁺ has the effect of increasing the refractive index (nd), but is also a component that increases the specific gravity of glass. In addition, as with Yb ³⁺ , the atomic weight of Lu ³⁺ is large, so it is preferable to reduce the content of Lu ³⁺ .

In addition, in the optical glass of the present embodiment, the upper limit of the content of Ge ⁴⁺ is preferably 3%, and further preferably 2.0%, 1.0%, 0.5%, and 0.1% in this order. In addition, the lower limit of the content of Ge ⁴⁺ is preferably 0%. In addition, the content of Ge ⁴⁺ may be 0%. Ge ⁴⁺ has the effect of increasing the refractive index (nd), but it is an extremely expensive component among commonly used glass components. In order to reduce the manufacturing cost of glass, the content of Ge ⁴⁺ is preferably in the above range.

In addition, in the optical glass of the present embodiment, the upper limit of the content of P ⁵⁺ is preferably 5%, and further preferably 4.0%, 3.0%, 2.0%, 1.0%, 0.5%, and 0.1%. In addition, the lower limit of the content of P ⁵⁺ is preferably 0%. In addition, the content of P ⁵⁺ may be 0%. P ⁵⁺ is a component that lowers the refractive index (nd) or a component that lowers the thermal stability of the glass. In order to produce glass with desired optical characteristics and excellent thermal stability, the content of P ⁵⁺ is preferably within the above range. However, P ⁵⁺ has the effect of suppressing the precipitation of crystals and preventing devitrification when the glass melt is cooled. Therefore, in order to obtain such an anti-devitrification effect, the lower limit of the content of P ⁵⁺ is preferably 0.1%, in order. More preferably, they are 0.3% and 0.5%.

For the optical glass of this embodiment, it is preferable that the cation component is mainly composed of the above-mentioned cation component, and the total content of the above-mentioned cation component [B ³⁺ +Si ⁴⁺ +Al ³⁺ +La ³⁺ +Gd ³⁺ +Y ^{3 +} +Yb ³⁺ +Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Ta ⁵⁺ +Bi ³⁺ +Zn ²⁺ +Li ⁺ +Na ⁺ +K ⁺ +Rb ⁺ +Cs ⁺ +Zr ⁴⁺ +Mg ²⁺ +Ca ²⁺ +Sr ²⁺ +Ba ²⁺ +Ga ³⁺ +In ³⁺ +Sc ³⁺ +Hf ⁴⁺ +Lu ³⁺ +Ge ⁴⁺ +P ⁵⁺ ] preferably greater than 95%, more It is preferably greater than 98.0%, further preferably greater than 99.0%, still further preferably greater than 99.5%, and still more preferably greater than 99.9%.

In addition, in the optical glass of the present embodiment, the upper limit of the content of Te ⁴⁺ is preferably 3%, and further preferably 2.0%, 1.0%, 0.5%, 0.1%, 0.05%, and 0.01% in this order. In addition, the lower limit of the content of Te ⁴⁺ is preferably 0%. In addition, the content of Te ⁴⁺ may be 0%. Te ⁴⁺ is a component that increases the refractive index (nd), but it is toxic, so it is preferable to reduce the content of Te ⁴⁺ .

Lead (Pb), arsenic (As), cadmium (Cd), thallium (Tl), beryllium (Be), and selenium (Se) are all toxic. Therefore, it is preferable not to contain these elements, that is, it is preferable not to include these elements in the glass as a glass component.

Uranium (U), thorium (Th), and radium (Ra) are all radioactive elements. Therefore, it is preferable not to contain these elements, that is, it is preferable not to include these elements in the glass as a glass component.

Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), Zirconium (Pr), Neodymium (Nd), Fe (Pm), Samarium (Sm), pin (Eu), ytterbium (Tb), dysprosium (Dy), 鈥 (Ho), erbium (Er), strontium (Tm), cerium (Ce) will cause the increase in the color of glass, fluorescent The source of light generation is preferably not an element contained in the optical glass. Therefore, it is preferable not to contain these elements, that is, it is preferable not to include these elements in the glass as a glass component.

Cobalt (Sb) and tin (Sn) are optionally added elements that function as clarifiers. Among them, Sb has a strong oxidizing property and oxidizes the molding surface of the compression molding die during precision compression molding. Therefore, during repeated press molding, the molding surface is significantly degraded and precision press molding cannot be performed. In addition, the surface quality of the molded optical element is degraded. Therefore, the content of Sb is preferably less than 1% by mass when converted to antimony trioxide (Sb ₂ O ₃ ) and the total content of glass components other than Sb ₂ O ₃ is set to 100% by mass. Further, it is more preferably 0.5% by mass or less, 0.1% by mass or less, 0.08% by mass or less, and 0.05% by mass or less. On the other hand, when the clarity of glass is improved by adding Sb, the content of Sb is converted to Sb ₂ O ₃ and the total content of glass components other than Sb ₂ O ₃ is set to 100 In the case of mass%, it is preferably 0.01 mass% or more, and more preferably 0.02 mass% or more and 0.04 mass% or more in this order.

In addition, the amount of Sn added is preferably 0 to 2% by mass when converted to tin dioxide (SnO ₂ ) and the total content of glass components other than SnO ₂ is set to 100% by mass, and is further changed in order. It is preferably 0 to 1% by mass, 0 to 0.5% by mass, 0 to 0.1% by mass, and 0 to 0.05% by mass.

The glass of the present invention is oxide glass. The range of the content of O ^2- as the anion component is preferably 95 to 100 anion %, and more preferably 97.0 to 100 anion %. It is still more preferably 99.0 to 100 anion %, still more preferably 99.5 to 100 anion %, still more preferably 99.9 to 100 anion %, still more preferably 100 anion %.

In addition, the optical glass of this embodiment may contain an anionic component other than O ^2- . As an anion component other than ^2- O, exemplary embodiments can be such as ^{F -, Cl -, Br -} , I -. ^{However, F -, Cl -, Br} -, I - are easily volatilized in the molten glass. Due to the volatilization of these components, problems such as changes in the characteristics of the glass, deterioration in the homogeneity of the glass, and loss of melting equipment become significant. Thus, the preferred F ^-, Cl ^-, Br ^- and I ^- total content is suppressed to amount by subtracting the content of O ^2- anions from 100%.

In addition, as is well known, the anion% means that all The total content of the anionic component of is set to the molar percentage at 100%.

In addition, the optical glass of the present embodiment is preferably basically composed of the above-mentioned components, but other components can also be contained within a range that does not hinder the effect of the present invention. In addition, in the present invention, the inclusion of unavoidable impurities is not excluded.

The glass composition of the optical glass of this embodiment can be quantified by, for example, ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry). 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 is 0%, and the absence or incorporation means that the constituent components are not substantially included, which means that the content of the constituent components is below the level of impurities.

<Characteristics of optical glass>

Hereinafter, the characteristics of the optical glass of the present embodiment will be described for each characteristic.

(Optical characteristics)

In the optical glass of this embodiment, the Abbe number (νd) is 43.5 to 47, and the refractive index (nd) satisfies the following formula (1).

When the Abbe number (νd) is 43.5 or more, the material as an optical element is effective for correction of chromatic aberration. In addition, when the Abbe number (νd) is greater than 47, if the refractive index (nd) is not decreased, the thermal stability of the glass significantly decreases, and devitrification is likely to occur during the manufacturing process of the glass. Therefore, the upper limit of the Abbe number is 47, which is The best is 46.5, and the better is 46.0. In addition, the lower limit of the Abbe number is 43.5, preferably 44.0, and more preferably 44.5.

In addition, by making the refractive index (nd) relative to the Abbe number (νd) within the range determined by the above formula (1), it becomes an optical glass with high utilization value in optical design. The upper limit of the refractive index (nd) is naturally determined according to the above-mentioned glass composition range. When the refractive index (nd) is excessively increased, the thermal stability tends to decrease. In order to obtain glass that maintains thermal stability and does not easily devitrify, the refractive index (nd) preferably satisfies the following formula (2).

(Glass transition temperature (Tg))

The upper limit of the glass transition temperature (Tg) of the optical glass of this embodiment is preferably 620°C, and further preferably 618°C, 617°C, and 615°C in this order. In addition, the lower limit of the glass transition temperature Tg is preferably 550°C, and further preferably 560°C, 570°C, and 580°C in this order. By making the upper limit of the glass transition temperature (Tg) satisfy the above range, high-precision precision press molding can be performed without excessively increasing the temperature of the press mold and the temperature of the glass during precision press molding. As a result, the loss of the compression molding die can be reduced, and the life of the compression molding die can be extended. In addition, by lowering the glass transition temperature (Tg), the reaction between the glass and the molding surface of the press molding die during precision press molding can be suppressed, and the surface quality of the optical element obtained by press molding can be improved.

(Light transmittance of glass)

In this embodiment, the light transmittance can be evaluated by the coloring degree (λ5) and the coloring degree (λ80).

Using glass having two planes parallel to each other and optically polished (thickness 10.0 mm±0.1 mm), light is incident perpendicularly to the plane from the plane on one side. Then, the ratio (Iout/Iin) of the intensity (Iout) of the transmitted light emitted from the plane on the other side to the intensity (Iin) of the incident light is calculated, that is, the external transmittance is calculated. Using a spectrophotometer, the external transmittance was measured while scanning the wavelength of incident light in the range of 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 short-wavelength side of the glass to the long-wavelength side, showing a high value.

λ5 is a wavelength at which the external transmittance becomes 5%, and λ80 is a wavelength at which the external transmittance is 80%. In the wavelength range of 280 to 700 nm, on the long wavelength side of λ5, the external transmittance of the glass shows a value greater than 5%. In addition, in the above-mentioned wavelength region, on the long wavelength side of λ80, the external transmittance of the glass shows a value greater than 80%.

Regarding λ80, by making it shorter in wavelength, it is possible to provide an optical element that can reproduce colors ideally. In addition, with regard to λ5, by shortening the wavelength, when an optical element made of glass is bonded using an ultraviolet-curable adhesive, the transmission amount of ultraviolet light of the glass can be sufficiently ensured (required for curing the adhesive) Amount).

For this reason, the preferred range of λ80 is 420 nm or less, the more preferred range is 410 nm or less, and the further preferred range is 400 nm or less. The target of the lower limit of λ80 is, for example, 350 nm. In addition, the preferable range of λ5 is 335 nm or less, and the more preferable range is 330 nm or less. The target of the lower limit of λ5 is, for example, 290 nm.

(Specific gravity of glass)

Although the optical glass of this embodiment is a high refractive index and low dispersion glass, the specific gravity is not large. Generally, if the specific gravity of glass can be reduced, the weight of the lens can be reduced. As a result, it is possible to reduce the power consumption for driving the autofocus of the lens mounted camera lens. On the other hand, when the specific gravity is excessively reduced, the refractive index (nd) and the thermal stability are reduced. Therefore, the upper limit of the specific gravity (d) of the glass is preferably 4.9, more preferably 4.85, and still more preferably 4.8. In addition, the lower limit of the specific gravity (d) of glass is preferably 4.2, more preferably 4.25, and further preferably 4.3.

(Liquidus temperature)

The upper limit of the liquidus temperature of the optical glass of this embodiment is preferably 1200°C, and further preferably 1180°C, 1170°C, 1160°C, and 1150°C in this order. In addition, the lower limit of the liquidus temperature is preferably 950°C, and further preferably 970°C, 980°C, and 990°C in this order. According to the optical glass of the present embodiment, the thermal stability of the glass can be improved. Therefore, it is possible to obtain a high refractive index and low dispersion glass with a low glass transition temperature (Tg) while reducing the content of Ta.

As described above, the optical glass according to the embodiment of the present invention has a large refractive index and Abbe number, is homogeneous, has little coloration, and has a low glass transition temperature (Tg). Such an optical glass can be suitably used as an optical glass for precision press molding in particular.

Second embodiment

2.25-0.01×νd。 As another aspect of the present invention, the optical glass of this embodiment is characterized by including B ₂ O ₃ , La ₂ O _3, and Nb ₂ O ₅ as essential components; the value (RE′) relative to the value (NWF′) ratio [RE '/ NWF'] is 0.30 to 0.70; values (the HR ') value (RE with respect to the' ratio) [HR '/ RE'] is 0.30 or less; the content of La ₂ O ₃ with respect to La ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ and Yb ₂ O ₃ The total content of the mass ratio (βw) = (La ₂ O ₃ /(La ₂ O ₃ +Gd ₂ O ₃ +Y ₂ O ₃ +Yb ₂ O _3)] contains less than 1 and not 0; the content of Nb ₂ O ₅ with respect to the mass of the total content of Nb ₂ O ₅ and Ta ₂ O ₅ ratio _{(γw) = [Nb 2 O} 5 / (Nb 2 O 5 + Ta ₂ O ₅ )] is 2/3 or more; the value (L') is -0.10 or more; Abbe number (νd) is 43.5~47, relative to the Abbe number (νd), the refractive index (nd) satisfies the following Formula (1): nd

2.25-0.01×νd.

Here, B ₂ O ₃ , SiO ₂ , Al ₂ O ₃ , La ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ , Yb ₂ O ₃ , Nb ₂ O ₅ , TiO ₂ , WO ₃ , Bi ₂ The molecular weights of O ₃ , Li ₂ O, Na ₂ O, K ₂ O, and ZnO are expressed as M(B ₂ O ₃ ), M(SiO ₂ ), M(Al ₂ O ₃ ), and M(La ₂ O ₃ ), M(Gd ₂ O ₃ ), M(Y ₂ O ₃ ), M(Yb ₂ O ₃ ), M(Nb ₂ O ₅ ), M(TiO ₂ ), M(WO ₃ ), M(Bi ₂ O ₃ ), M (Li ₂ O), M (Na ₂ O), M (K ₂ O), and M (ZnO); in the content ratio of each of the above components expressed in mass% when the value represented: the above value (NWF ') is twice the value of the content of B ₂ O ₃ is divided by M (B ₂ O ₃₎ value, the value of the content of SiO ₂ is divided by M (SiO ₂ ) the total value of the value divided by 2 times the value of Al ₂ O ₃ content divided by the value of M (Al ₂ O ₃ ); the above value (RE') is the value divided by the value of La ₂ O ₃ content The value of M(La ₂ O ₃ ), the value of Gd ₂ O ₃ content divided by the value of M(Gd ₂ O ₃ ), the value of Y ₂ O ₃ content divided by M(Y ₂ O ₃ ) and the value of the content of Yb ₂ O ₃ value is divided by M (Yb ₂ O ₃₎ of a value twice the value of the sum value; and the value (HR ') is twice the value of the content of Nb ₂ O ₅ Divide the value of M(Nb ₂ O ₅ ), divide the value of TiO ₂ content by the value of M(TiO ₂ ), divide the value of WO ₃ content by the value of M(WO ₃ ), and divide the value of Bi ₂ O 2x ₃ content value is divided by M (Bi ₂ O ₃₎ a sum of values; above-mentioned value (L ') is 12 times the value of the content of Li ₂ O is divided by M (Li ₂ O) of Value, divide 4 times the value of Na ₂ O content by the value of M(Na ₂ O), divide 2 times the value of K ₂ O content by the value of M(K ₂ O), and divide the content of ZnO value divided by two times M (ZnO) by subtracting the total value of twice the value of the content of SiO ₂ is divided by M (SiO ₂₎ values, the value of 2 times the content of Al ₂ O ₃ divided by M (Al ₂ O ₃₎ and the numerical value of the content of B ₂ O ₃ is divided by M (B ₂ O ₃₎ the value of the total value of the values.

That is, when B ₂ O ₃ , SiO ₂ , Al ₂ O ₃ , La ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ , Yb ₂ O ₃ , Nb ₂ O ₅ , TiO ₂ , expressed in mass% The values of WO ₃ , Bi ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, and ZnO are only expressed as B ₂ O ₃ , SiO ₂ , Al ₂ O ₃ , La ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ , Yb ₂ O ₃ , Nb ₂ O ₅ , TiO ₂ , WO ₃ , Bi ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, ZnO, NWF', RE', HR' and L'can be expressed as follows.

NWF'=[2×B ₂ O ₃ /M(B ₂ O ₃ )]+[SiO ₂ /M(SiO ₂ )]+[2×Al ₂ O ₃ /M(Al ₂ O ₃ )]

RE'=2×{[La ₂ O ₃ /M(La ₂ O ₃ )]+[Gd ₂ O ₃ /M(Gd ₂ O ₃ )]+[Y ₂ O ₃ /M(Y ₂ O ₃ )] +[Yb ₂ O ₃ /M(Yb ₂ O ₃ )]}

HR'=[2×Nb ₂ O ₅ /M(Nb ₂ O ₅ )]+[TiO ₂ /M(TiO ₂ )]+[WO ₃ /M(WO ₃ )]+[2×Bi ₂ O ₃ / M(Bi ₂ O ₃ )]

L'=[12×Li ₂ O/M(Li ₂ O)]+[4×Na ₂ O/M(Na ₂ O)]+[2×K ₂ O/M(K ₂ O)]+[2 ×ZnO/M(ZnO)]-{[2×SiO ₂ /M(SiO ₂ )]+[2×Al ₂ O ₃ /M(Al ₂ O ₃ )]+[B ₂ O ₃ /M(B ₂ O ₃ )]}

In addition, in the above formula, it is expressed as B ₂ O ₃ , SiO ₂ , Al ₂ O ₃ , La ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ , Yb ₂ O ₃ , Nb ₂ O ₅ , TiO ₂ , The content of each component of WO ₃ , Bi ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, and ZnO was originally the content ratio of each component expressed in mass %, but it is only treated as a numerical value here, and it is not shown Additional mass% or% units. In addition, the molecular weight is a dimensionless number. Therefore, NWF', RE', HR', and L'are only numerical values, and no additional units such as mass% or% are added. Therefore, in this embodiment, the lower limit of L'is represented as -0.10.

In this embodiment, as the second aspect of the present invention, the optical glass of the present invention will be described based on the content ratio of each component expressed in mass %. Therefore, unless otherwise specified, each content is expressed in mass %.

In addition, in this specification, as is well known, expressing by mass% refers to a mass percentage when the total content of all components converted to oxides is 100%. In addition, the total content refers to the total amount of the conversion of a plurality of components into oxide content (including the case where the content is 0%). In addition, the mass ratio refers to a ratio (ratio) of each component expressed as mass %, converted into an oxide content (a total content of a plurality of components including oxide conversion).

Hereinafter, the optical glass of this embodiment will be described in detail.

The optical glass of this embodiment contains B ₂ O ₃ , La ₂ O ₃ and Nb ₂ O ₅ as essential components.

In the optical glass of this embodiment, the ratio [RE'/NWF'] of the value (RE') to the value (NWF') is 0.30 or more. By making the ratio [RE'/NWF'] satisfy the above range, the desired refractive index and Abbe number can be obtained. In addition, when the ratio [RE'/NWF'] is 0.70 or less, it is possible to obtain a glass that maintains the thermal stability of the glass in a good state and hardly precipitates crystals during the manufacturing process. In addition, the upper limit of the ratio [RE'/NWF'] is preferably 0.60, and further preferably 0.50, 0.45, 0.44, and 0.43 in this order. In addition, the lower limit of the ratio [RE'/NWF'] is preferably 0.32, and further preferably 0.34, 0.36, 0.37, 0.38, and 0.39 in this order.

In the optical glass of the present embodiment, the value (NWF') is the value of each content of B ₂ O ₃ , SiO _2, and Al ₂ O ₃ as network forming components expressed in mass% divided by the molecular weight of each component, Multiply the total value of the number of cations contained in each molecule (value (NWF')=[2×B ₂ O ₃ /M(B ₂ O ₃ )]+[SiO ₂ /M(SiO ₂ ) ]+[2×Al ₂ O ₃ /M(Al ₂ O ₃ )]). When the value (NWF') increases, the thermal stability of the glass can be improved, and crystals are not easily precipitated during the manufacturing process, but the refractive index decreases.

In addition, in the optical glass of this embodiment, the ratio [2×B ₂ O ₃ /M(B ₂ O ₃ )]: [SiO ₂ /M(SiO ₂ )]: [2×Al ₂ O ₃ /M(Al ₂ O ₃ )] is the same as the ratio B ³⁺ : Si ⁴⁺ : Al ³⁺ expressed in cation %. In addition, the value (NWF') corresponds to the total content (NWF) expressed in% of cations in the optical glass of the first embodiment.

In the optical glass of this embodiment, the preferable upper limit of the value (NWF') is 1.0, and further preferably 0.95, 0.90, 0.85, and 0.80 in this order. The preferable lower limit of the value (NWF') is 0.30, and further preferably 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.62, and 0.65.

In the optical glass of this embodiment, the value (RE') is each of La ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ , and Yb ₂ O ₃ as high-refractive-index and low-dispersion components expressed in mass %. The value of the content is divided by the molecular weight of each component, and then multiplied by the total number of cations contained in each molecule (value (RE')=[2×La ₂ O ₃ /M(La ₂ O ₃ )]+[2×Gd ₂ O ₃ /M(Gd ₂ O ₃ )]+[2×Y ₂ O ₃ /M(Y ₂ O ₃ )]+[2×Yb ₂ O ₃ /M(Yb ₂ O ₃ ))). When the value (RE') increases, the refractive index increases while maintaining low dispersion characteristics, but the thermal stability of the glass decreases, and crystals are easily precipitated during the manufacturing process.

In addition, in the optical glass of the present embodiment, the ratio [2×La ₂ O ₃ /M(La ₂ O ₃ )]: [2×Gd ₂ O ₃ /M(Gd ₂ O ₃ )]: [2×Y ₂ O ₃ /M(Y ₂ O ₃ )]: [2×Yb ₂ O ₃ /M(Yb ₂ O ₃ )] and the ratio expressed in cation% La ³⁺ : Gd ³⁺ : Y ³⁺ : Yb ^{3 +} same. In addition, the value (RE') corresponds to the total content (RE) expressed in% of cations in the optical glass of the first embodiment.

In the optical glass of this embodiment, the preferable upper limit of the value (RE') is 0.6, and further preferably 0.55, 0.50, 0.45, 0.40, and 0.35 in this order. The preferable lower limit of the value RE' is 0.1, and it is more preferably 0.15, 0.20, 0.22, and 0.25 in this order.

In the optical glass of this embodiment, the ratio [HR'/RE'] of the value (HR') to the value (RE') is 0.30 or less. By setting the ratio [HR'/RE'] to the above range, the refractive index can be increased while maintaining low dispersion characteristics, and thus a glass having a desired refractive index and Abbe number can be obtained. In addition, it is possible to improve the meltability and make it difficult for the glass raw material to produce molten residue. Furthermore, it is also possible to suppress fusion between the glass and the press mold during precision press molding, and the glass surface after press molding from becoming opaque.

The upper limit of the ratio [HR'/RE'] is preferably 0.24, and further preferably 0.19, 0.17, 0.16, and 0.15 in this order. In addition, in order to increase the refractive index while maintaining the thermal stability of the glass in the glass, it is preferable that the oxide of the rare earth element coexist with a high refractive index and high dispersion component such as Nb ₂ O ₅ . In order to achieve high refractive index while maintaining good thermal stability in this way, the lower limit of [HR'/RE'] is preferably 0.03, and more preferably 0.05, 0.06, 0.07, 0.08 in this order.

In the optical glass of the present embodiment, the value (HR') is niobium pentoxide (Nb ₂ O ₅ ), titanium dioxide (TiO ₂ ), and tungsten oxide (WO ₃ ) The value of each content of bismuth trioxide (Bi ₂ O ₃ ) divided by the molecular weight of each component and multiplied by the number of cations contained in each molecule (value (HR')) =[2×Nb ₂ O ₅ /M(Nb ₂ O ₅ )]+[TiO ₂ /M(TiO ₂ )]+[WO ₃ /M(WO ₃ )]+[2×Bi ₂ O ₃ /M( Bi ₂ O ₃ )]). When the value HR' increases, the refractive index increases and the Abbe number decreases, so that the high refractive index and high dispersion become. In addition, when the value (HR') increases, there is a risk that the surface of the press-formed glass becomes opaque or the glass fuses to the press-forming mold due to the reaction of the glass with the press-forming mold during precision press molding .

In addition, in the optical glass of the present embodiment, the ratio [2×Nb ₂ O ₅ /M(Nb ₂ O ₅ )]: [TiO ₂ /M(TiO ₂ )]: [WO ₃ /M(WO ₃ )] : [2×Bi ₂ O ₃ /M(Bi ₂ O ₃ )] is the same as the ratio expressed in% of cations Nb ⁵⁺ : Ti ⁴⁺ : W ⁶⁺ : Bi ³⁺ . In addition, the value (HR') corresponds to (HR) expressed in% of cations in the optical glass of the first embodiment.

In the optical glass of the present embodiment, the preferable upper limit of the value (HR') is 0.08, and further preferably 0.07, 0.06, and 0.05 in this order. The preferred lower limit of the value (HR') is 0.005, and further preferably 0.007, 0.008, 0.01, and 0.015.

The optical glass of this embodiment has a relatively low glass transition temperature (Tg), and is suitable for precision press molding, for example. Here, as components that affect the glass transition temperature (Tg), focus on lithium oxide (Li ₂ O), sodium oxide (Na ₂ O), potassium oxide (K ₂ O), zinc oxide (ZnO), silicon dioxide Seven components (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), and boron trioxide (B ₂ O ₃ ) will be described regarding the relationship between the content of these components and the glass transition temperature (Tg).

Among these seven components, components having an effect of lowering the glass transition temperature (Tg) are four components of Li ₂ O, Na ₂ O, K ₂ O, and ZnO. Conversely, the components having an effect of increasing the glass transition temperature (Tg) are three components of SiO ₂ , Al ₂ O ₃ , and B ₂ O ₃ .

The results of research by the inventors of the present application indicate that there is a correlation between the value (L') and the glass transition temperature (Tg), where the value (L') is the content of each of these 7 components expressed in mass% The numerical value is divided by the molecular weight of each component, multiplied by the number of cations contained in each molecule, and then multiplied by the total value of the value of the degree of influence of each component on the glass transition temperature (Tg) as a coefficient. In addition, based on the cation ratio, the influence degrees of Li ₂ O, Na ₂ O, K ₂ O, ZnO, SiO ₂ , Al ₂ O ₃ , and B ₂ O ₃ on the glass transition temperature (Tg) are +6, +2, +1, +2, -2, -1, -0.5.

Such a value (L') can be expressed as L'=[6×2×Li ₂ O/M(Li ₂ O)]+[2×2×Na ₂ O/M(Na ₂ O)]+[1× 2×K ₂ O/M(K ₂ O)]+[2×1×ZnO/M(ZnO)]+[-2×1×SiO ₂ /M(SiO ₂ )]+[-1×2×Al ₂ O ₃ /M(Al ₂ O ₃ )]+[-0.5×2×B ₂ O ₃ /M(B ₂ O ₃ )].

FIG. 2 plots the value (L′) and the known glass including B ₂ O ₃ and La ₂ O ₃ with the vertical axis as the glass transition temperature (Tg) and the horizontal axis as the value (L′). A graph of the relationship of Tg. It can be clearly seen from FIG. 2 that the points are basically distributed on a straight line, and there is a correlation between the value (L′) and Tg.

Therefore, by setting the value (L') to -0.10 or more, the glass transition temperature (Tg) can be lowered, and glass suitable for, for example, precision press molding can be provided. In addition, by setting the value (L') to -0.10 or more, the meltability of the glass can be improved. In order to lower the glass transition temperature (Tg) and further improve the meltability of the glass, the lower limit of the value (L') is preferably -0.09, and more preferably -0.08, -0.06, -0.04, -0.02, and 0 in this order.

In addition, as the value (L’) increases, it shows that the refractive index The thermal stability of the product tends to decrease, so in order to obtain the required refractive index and Abbe number while maintaining the thermal stability in a good state, the upper limit of the value (L') is preferably 1.0, and more preferably in order 0.60, 0.40, 0.30, 0.20, 0.18.

In addition, in the optical glass of this embodiment, the ratio [2×Li ₂ O/M(Li ₂ O)]: [2×Na ₂ O/M(Na ₂ O)]: [2×K ₂ O/M (K ₂ O)]: [ZnO/M(ZnO)]: [SiO ₂ /M(SiO ₂ )]: [2×Al ₂ O ₃ /M(Al ₂ O ₃ )]: [2×B ₂ O ₃ /M(B ₂ O ₃ )] is the same as the ratio expressed in% of cations Li ⁺ : Na ⁺ : K ⁺ : Zn ²⁺ : Si ⁴⁺ : Al ³⁺ : B ³⁺ . In addition, the value (L') corresponds to the value (L) represented by the cation% in the optical glass of the first embodiment.

<glass composition>

Hereinafter, the glass composition will be described in detail. In addition, unless otherwise specified, the contents of various constituent components and the like are expressed in terms of mass% based on oxides. In addition, in the present embodiment, as described above, the glass composition is operated by multiplying the content (mass %) of each component by the number of cations contained in the oxide, and then the content (mass of each component) %) Divided by the molecular weight of each component. However, regarding other matters, the optical glass of the present embodiment and the optical glass of the first embodiment have many things in common. Therefore, in the following description, the content common to the first embodiment (for example, the reason for determining the numerical range of the glass composition, etc.) will be partially omitted.

In the optical glass of this embodiment, the total content of B ₂ O ₃ , SiO ₂ , La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ and Yb ₂ O ₃ [B ₂ O ₃ +SiO ₂ +La ₂ O ₃ +Gd ₂ O ₃ +Y ₂ O ₃ +Yb ₂ O ₃ ] is preferably 65% or more. By making the total content [B ₂ O ₃ +SiO ₂ +La ₂ O ₃ +Gd ₂ O ₃ +Y ₂ O ₃ +Yb ₂ O ₃ ] into the above range, it is easy to maintain the thermal stability in a good state At the same time to achieve the desired refractive index (nd) and Abbe number (νd).

The upper limit of the total content [B ₂ O ₃ +SiO ₂ +La ₂ O ₃ +Gd ₂ O ₃ +Y ₂ O ₃ +Yb ₂ O ₃ ] is preferably 90%, and further preferably 88.0%, 86.0%, 84.0%, 82.0%, 80.0%. In addition, the lower limit of the total content [B ₂ O ₃ +SiO ₂ +La ₂ O ₃ +Gd ₂ O ₃ +Y ₂ O ₃ +Yb ₂ O ₃ ] is 65%, preferably 67%, and further preferably 70.0%, 71.0%, 72.0%, 73.0%.

In the optical glass of this embodiment, the upper limit of the total content of B ₂ O ₃ , SiO ₂ and Al ₂ O ₃ (NWFw)=[B ₂ O ₃ +SiO ₂ +Al ₂ O ₃ ] is preferably 35%, In turn, it is more preferably 32.0%, 30.0%, and 29.0%. In addition, the lower limit of the total content (NWFw) is preferably 15%, and further preferably 16.0%, 18.0%, 20.0%, 21.0%, and 22.0% in order.

In the optical glass of this embodiment, lanthanum trioxide (La ₂ O ₃ ), yttrium trioxide (Y ₂ O ₃ ), gallium trioxide (Gd ₂ O ₃ ), and trioxide mirror (Yb ₂ O ₃ ) The ratio of the total content (REw) to the total content of B ₂ O ₃ , SiO ₂ and Al ₂ O ₃ (NWFw), that is, the mass ratio (αw)=[REw/NWFw] is preferably 1.4 to 2.6. When the mass ratio (αw) is too small, the refractive index (nd) and Abbe number (νd) tend to decrease. On the other hand, when the mass ratio (αw) is too large, the thermal stability of the glass tends to decrease, and the glass transition temperature (Tg) also tends to increase.

The upper limit of the mass ratio (αw) is preferably 2.6, and further preferably 2.5, 2.4, 2.3, 2.2, 2.1, 2.0 in this order. The lower limit of the mass ratio αw is preferably 1.4, and further preferably 1.5 and 1.6 in order.

In the optical glass of this embodiment, the total content (REw) of La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ and Yb ₂ O ₃ = [La ₂ O ₃ +Gd ₂ O ₃ +Y ₂ O ₃ The upper limit of +Yb ₂ O ₃ ] is preferably 61%, and further preferably 59.0%, 57.0%, 55.0%, 54.0%, and 53.0%. In addition, the lower limit of the total content REw is preferably 39%, and further preferably 42.0%, 45.0%, 46.0%, and 47.0%.

In the optical glass of this embodiment, the upper limit of the content of B ₂ O ₃ is preferably 35%, and further preferably 32.0%, 30.0%, 29.0%, 28.0%, and 27.0%. In addition, the lower limit of the content of B ₂ O ₃ is preferably 16%, and further preferably 18.0%, 20.0%, 21.0%, and 22.0% in this order.

In the optical glass of the present embodiment, the upper limit of the content of SiO ₂ is preferably 10%, and further preferably 8.0%, 7.0%, 6.0%, 5.0%, and 4.0% in this order. In addition, the lower limit of the content of SiO ₂ is preferably 0%, and further preferably 0.05%, 0.1%, 0.2%, 0.4%, and 0.5%.

In the optical glass of the present embodiment, the upper limit of the content of Al ₂ O ₃ is preferably 3%, and further preferably 2.5%, 2%, 1.5%, 1%, 0.5%, and 0.1%. In addition, the lower limit of the content of Al ₂ O ₃ is preferably 0%. In addition, the content of Al ₂ O ₃ may be 0%.

Further, in the optical glass of the present embodiment, the content of B ₂ O ₃ with respect to B ₂ O _3, the proportion of SiO ₂ and Al total content (NWFw) in ₂ O _3, i.e., the mass ratio [B ₂ O ₃ / NWFw The upper limit of] is preferably 0.99, and further preferably 0.98 and 0.97 in this order. In addition, the lower limit of the mass ratio [B ₂ O ₃ /NWFw] is preferably 0.5, and further preferably 0.60, 0.65, 0.70, 0.80, 0.85, 0.86 in this order.

In the optical glass of this embodiment, La ₂ O ₃ is an essential component. The upper limit of the content of La ₂ O ₃ is preferably 50%, and more preferably 48.0%, 47.0%, 45.0%, 44.0%, 43.0%, and 42.0%. In addition, the lower limit of the content of La ₂ O ₃ is preferably 10%, and further preferably 15.0%, 17.0%, 19.0%, 20.0%, 21.0%, and 22.0%.

In the optical glass of this embodiment, the upper limit of the content of Gd ₂ O ₃ is preferably 50%, and further preferably 45.0%, 40.0%, 35.0%, 33.0%, 32.0%, 31.0%, 30.0%, and 27.0 %. In addition, the lower limit of the content of Gd ₂ O ₃ is preferably 0%, and further preferably 1.0%, 2.0%, 3.0%, 4.0%, and 5.0%.

In the optical glass of the present embodiment, the upper limit of the content of Y ₂ O ₃ is preferably 20%, and further preferably 17.0%, 15.0%, 13.0%, 12.0%, 11.0%, and 10.0%. In addition, the lower limit of the content of Y ₂ O ₃ is preferably 0%.

In the optical glass of the present embodiment, the upper limit of the content of Yb ₂ O ₃ is preferably 3%, and further preferably 2.5%, 2.0%, 1.5%, 1.0%, and 0.5%. In addition, the lower limit of the content of Yb ₂ O ₃ is preferably 0%. In addition, the content of Yb ₂ O ₃ may be 0%.

In the optical glass of the present embodiment, the content of La ₂ O ₃ with respect to _{La 2 O 3, Y 2 O} 3, Gd ratio ₂ O ₃ and Yb total content (REW) in ₂ O _3, i.e., the mass ratio (βw )=[La ₂ O ₃ /REw] is less than 1 and does not contain 0. By setting the mass ratio (βw) within the above range, it is possible to maintain thermal stability and meltability in a good state.

The mass ratio (βw) is less than 1, and the upper limit thereof is preferably 0.98, and further preferably 0.95, 0.90, 0.88, and 0.87 in this order. In addition, the lower limit of the mass ratio (βw) is preferably 0.27, and further preferably 0.30, 0.35, 0.37, 0.39, 0.40, 0.41 in this order.

In addition, in the optical glass of this embodiment, the total content of Gd ₂ O ₃ and Y ₂ O ₃ relative to the total content of La ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O _3, and Yb ₂ O ₃ (REw) , The upper limit of the mass ratio [(Gd ₂ O ₃ +Y ₂ O ₃ )/REw] is preferably 0.8, and in turn, it is more preferably 0.70, 0.65, 0.61, 0.60, 0.59. In addition, the lower limit of the mass ratio [(Gd ₂ O ₃ +Y ₂ O ₃ )/REw] is preferably 0, and in turn, more preferably 0.05, 0.07, 0.09, 0.10, 0.11, 0.12, and 0.13.

In the optical glass of this embodiment, the total content (HRw) of Nb ₂ O ₅ , TiO ₂ , WO ₃ , Ta ₂ O ₅ and Bi ₂ O ₃ = [Nb ₂ O ₅ +TiO ₂ +WO ₃ +Ta ₂ O ₅ +Bi ₂ O ₃ ] is preferably less than 20%. By making the total content (HRw) within the above range, it is easy to suppress the decrease in Abbe number (νd) and achieve desired optical characteristics, and it is easy to maintain the thermal stability of the glass in a good state.

In the optical glass of the present embodiment, the total content (HRw) is preferably less than 20%, and the upper limit thereof is more preferably 14%, 10.0%, 9.0%, 8.0%, and 7.0%. In addition, the lower limit of the total content (HRw) is preferably 0.1%, and further preferably 0.2%, 0.5%, 1.0%, 1.5%, 2.0%, and 3.0%.

In the optical glass of the present embodiment in, Nb ₂ O ₅ content with respect to the ratio of Nb ₂ O ₅ and Ta ₂ O ₅ total content, i.e., the mass ratio _{(γw) = [Nb 2 O} 5 / (Nb 2 O 5 +Ta ₂ O ₅ )] is 2/3 or more. By setting the mass ratio (γw) to the above range, it is possible to stably obtain glass having good thermal stability and desired optical characteristics.

The lower limit of the mass ratio (γw) is 2/3, preferably 0.67, and further preferably 0.68, 0.70, 0.80, and 0.90. In addition, the upper limit of the mass ratio (γw) is preferably 1.

In addition, in the optical glass of this embodiment, the total content of Nb ₂ O ₅ , TiO ₂ and WO ₃ relative to the total content of Nb ₂ O ₅ , TiO ₂ , WO ₃ , Ta ₂ O ₅ and Bi ₂ O ₃ ( The upper limit of the ratio of HRw), that is, the mass ratio [(Nb ₂ O ₅ +TiO ₂ +WO ₃ )/HRw] is preferably 1. In addition, the lower limit of the mass ratio [(Nb ₂ O ₅ +TiO ₂ +WO ₃ )/HRw] is preferably 0.3, and further preferably 0.40, 0.50, 0.60, 0.70, 0.80, 0.90 in this order. In addition, the mass ratio [(Nb ₂ O ₅ +TiO ₂ +WO ₃ )/HRw] may be 1.

In addition, in the optical glass of this embodiment, the upper limit of the total content of [Nb ₂ O ₅ +TiO ₂ +WO ₃ ] of Nb ₂ O ₅ , TiO _2, and WO ₃ is preferably 12%, and further preferably 10.0 %, 9.0%, 8.0%, 7.0%, 6.0%. In addition, the lower limit of the total content [Nb ₂ O ₅ +TiO ₂ +WO ₃ ] is preferably 0.1%, and further preferably 0.2%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, and 3.0%. By making the total content [Nb ₂ O ₅ +TiO ₂ +WO ₃ ] into the above range, the effects and effects of the high refractive index and high dispersion component can be obtained while reducing the content of Ta ₂ O ₅ and Bi ₂ O ₃ .

Further, in the optical glass of the present embodiment in, Nb ₂ O ₅ content with respect of Nb ₂ O _5, the proportion of Ta ₂ O ₅ and WO total content _3, i.e., the mass ratio _{[Nb 2 O 5 / (Nb} 2 O ₅ +Ta ₂ O ₅ +WO ₃ )] preferably has an upper limit of 1. In addition, the lower limit of the mass ratio [Nb ₂ O ₅ /(Nb ₂ O ₅ +Ta ₂ O ₅ +WO ₃ )] is preferably 0.1, and further preferably 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80 , 0.90. In addition, the mass ratio [Nb ₂ O ₅ /(Nb ₂ O ₅ +Ta ₂ O ₅ +WO ₃ )] may also be 1. By setting the mass ratio [Nb ₂ O ₅ /(Nb ₂ O ₅ +Ta ₂ O ₅ +WO ₃ )] to the above range, it is possible to obtain less coloration and excellent thermal stability while reducing the content of Ta ₂ O ₅ Glass.

Further, in the optical glass of the present embodiment in, Nb ₂ O ₅ content of the ratio Nb total content ₂ O ₅ and WO _3, i.e. the mass ratio _{[Nb 2 O 5 / (Nb} 2 O 5 + WO 3) The upper limit of] is preferably 1. In addition, the lower limit of the mass ratio [Nb ₂ O ₅ /(Nb ₂ O ₅ +WO ₃ )] is preferably 0.1, and further preferably 0.20, 0.30, 0.40, 0.50, 0.60, 0.65, 0.70, 0.80, 0.90. In addition, the mass ratio [Nb ₂ O ₅ /(Nb ₂ O ₅ +WO ₃ )] may be 1. By setting the mass ratio [Nb ₂ O ₅ /(Nb ₂ O ₅ +WO ₃ )] to the above range, it is possible to obtain glass with less coloring while maintaining good thermal stability.

Furthermore, in the optical glass of this embodiment, the total content of TiO ₂ , WO ₃ and Bi ₂ O ₃ [TiO ₂ +WO ₃ +Bi ₂ O ₃ ] is preferably less than 10, and the upper limit thereof is more preferably 9.0% , 8.0%, 7.0%, 6.0%, 5.0%, 4.0%, 3.0%, 2.0%, 1.0%, 0.5%, 0.2%, 0.1%. In addition, the lower limit of the total content [TiO ₂ +WO ₃ +Bi ₂ O ₃ ] is preferably 0%.

In the optical glass of this embodiment, Nb ₂ O ₅ is an essential component. The upper limit of the content of Nb ₂ O ₅ is preferably 12%, and further preferably 10.0%, 8.0%, 7.0%, and 6.0%. In addition, the lower limit of the content of Nb ₂ O ₅ is preferably 0.1%, and further preferably 0.5%, 1.0%, and 1.5%.

In the optical glass of this embodiment, the upper limit of the content of TiO ₂ is preferably 5%, and further preferably 4.0%, 3.0%, 2.0%, and 1.5% in this order. In addition, the lower limit of the content of TiO ₂ is preferably 0%. In addition, the content of TiO ₂ may be 0%.

In the optical glass of the present embodiment, the upper limit of the content of WO ₃ is preferably 12%, and further preferably 10.0%, 7.0%, 5.0%, and 4.0% in this order. In addition, the lower limit of the content of WO ₃ is preferably 0%. In addition, the content of WO ₃ may be 0%.

In the optical glass of this embodiment, the upper limit of the content of Ta ₂ O ₅ is preferably 3%, and further preferably 2.5%, 2.0%, 1.5%, 1.0%, 0.9%, 0.7%, 0.5%, 0.1 %. In addition, the lower limit of the content of Ta ₂ O ₅ is preferably 0%. In addition, the content of Ta ₂ O ₅ may be 0%.

In the optical glass of the present embodiment, the upper limit of the content of Bi ₂ O ₃ is preferably 3%, and further preferably 2.5%, 2.0%, 1.5%, 1.0%, 0.5%, and 0.1%. In addition, the lower limit of the content of Bi ₂ O ₃ is preferably 0%. In addition, the content of Bi ₂ O ₃ may be 0%.

In addition, in the optical glass of this embodiment, the total content (REw) of La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O _3, and Yb ₂ O ₃ is relative to Nb ₂ O ₅ , TiO ₂ , WO ₃ , Ta The ratio of the total content (HRw) of ₂ O ₅ and Bi ₂ O ₃ , that is, the upper limit of the mass ratio [REw/HRw] is preferably 25, and further preferably 20.0, 19.0, 18.0, and 17.0 in this order. In addition, the lower limit of the mass ratio [REw/HRw] is preferably 3, and further preferably 4.0, 5.0, and 6.0 in order.

In addition, in the optical glass of this embodiment, the total content (HRw) of Nb ₂ O ₅ , TiO ₂ , WO ₃ , Ta ₂ O ₅ and Bi ₂ O ₃ relative to B ₂ O ₃ , SiO ₂ and Al ₂ O The ratio of the total content (NWFw) of ₃ , that is, the upper limit of the mass ratio [HRw/NWFw] is preferably 0.4, and further preferably 0.35, 0.30, and 0.25 in this order. The lower limit of the mass ratio [HRw/NWFw] is preferably 0.05, and further preferably 0.07, 0.08, 0.09, 0.10, and 0.11 in this order.

The optical glass of this embodiment preferably further contains ZnO.

In the optical glass of this embodiment, the upper limit of the content of ZnO is preferably 25%, and further preferably 22.0%, 20.0%, 19.0%, 18.0%, and 17.0%. In addition, the lower limit of the content of ZnO is preferably 4%, and further preferably 5.0%, 8.0%, 9.0%, and 10.0%.

The optical glass of this embodiment preferably contains at least one kind selected from Li ₂ O, Na ₂ O, and K ₂ O.

In the optical glass of the present embodiment, the upper limit of the content of Li ₂ O is preferably 5%, and further preferably 4.0%, 3.0%, 2.5%, 2.0%, 1.5%, 1.0%, 0.8%, 0.6% . In addition, the lower limit of the content of Li ₂ O is preferably 0%.

In the optical glass of this embodiment, the upper limit of the content of Na ₂ O is preferably 3%, and further preferably 2.5%, 2.0%, 1.5%, 1.0%, 0.5%, and 0.1%. In addition, the lower limit of the content of Na ₂ O is preferably 0%. In addition, the content of Na ₂ O may be 0%.

In the optical glass of the present embodiment, the upper limit of the content of K ₂ O is preferably 3%, and further preferably 2.5%, 2.0%, 1.5%, 1.0%, 0.5%, and 0.1%. In addition, the lower limit of the content of K ₂ O is preferably 0%. In addition, the content of K ₂ O may be 0%.

In the optical glass of 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 5%, and further preferably 4.0 %, 3.0%, 2.5%, 2.0%, 1.5%, 1.0%, 0.5%, 0.1%. In addition, the lower limit of the total content [Li ₂ O+Na ₂ O+K ₂ O] is preferably 0%.

In addition, the optical glass of this embodiment may contain any one or more types of Rb ₂ O and Cs ₂ O.

In the optical glass of this embodiment, the upper limit of the content of Rb ₂ O is preferably 3%, and further preferably 2.5%, 2.0%, 1.5%, 1.0%, 0.5%, and 0.1% in this order. In addition, the lower limit of the content of Rb ₂ O is preferably 0%.

In the optical glass of the present embodiment, the upper limit of the content of Cs ₂ O is preferably 3%, and further preferably 2.5%, 2.0%, 1.5%, 1.0%, 0.5%, and 0.1% in this order. In addition, the lower limit of the content of Cs ₂ O is preferably 0%.

In addition, in the optical glass of this embodiment, the upper limit of the total content of Rb ₂ O and Cs ₂ O [Rb ₂ O+Cs ₂ O] is preferably 3%, and further preferably 2.5%, 2.0%, 1.5 %, 1.0%, 0.5%, 0.1%. In addition, the lower limit of the total content [Rb ₂ O+Cs ₂ O] is preferably 0%. In addition, the total content [Rb ₂ O+Cs ₂ O] may be 0%.

The optical glass of this embodiment preferably further contains zirconium dioxide (ZrO ₂ ).

In the optical glass of the present embodiment, the upper limit of the content of ZrO ₂ is preferably 15%, and further preferably 12.0%, 10.0%, 9.0%, 8.5%, and 8.0%. In addition, the lower limit of the content of ZrO ₂ is preferably 0%, and further preferably 0.1%, 0.3%, 0.5%, 0.6%, 0.7%, and 1.0%.

The optical glass of this embodiment may further contain the following components as necessary.

In the optical glass of the present embodiment, the upper limit of the content of magnesium oxide (MgO) is preferably 3%, and further preferably 2.5%, 2.0%, 1.5%, 1.0%, and 0.7%. In addition, the lower limit of the content of MgO is preferably 0%. In addition, the content of MgO may be 0%.

In the optical glass of this embodiment, the upper limit of the content of calcium oxide (CaO) is preferably 3%, and further preferably 2.5%, 2.0%, 1.5%, 1.0%, and 0.5% in this order. In addition, the lower limit of the content of CaO is preferably 0%. In addition, the content of CaO may be 0%.

In the optical glass of the present embodiment, the upper limit of the content of strontium oxide (SrO) is preferably 4%, and further preferably 3.5%, 3.0%, 2.5%, 1.0%, and 0.5%. In addition, the lower limit of the SrO content is preferably 0%. In addition, the content of SrO may be 0%.

In the optical glass of this embodiment, the upper limit of the content of barium oxide (BaO) is preferably 7%, and further preferably 6.0%, 5.0%, 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 BaO is preferably 0%. In addition, the content of BaO may be 0%.

In the optical glass of this embodiment, MgO, CaO, SrO and The upper limit of the total content of BaO [MgO+CaO+SrO+BaO] is preferably 7%, and further preferably 6.0%, 5.0%, 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 total content [MgO+CaO+SrO+BaO] is preferably 0%. In addition, the total content [MgO+CaO+SrO+BaO] may be 0%.

In the optical glass of the present embodiment, the upper limit of the content of gallium trioxide (Ga ₂ O ₃ ) is preferably 3%, and further preferably 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%. In addition, the content of Ga ₂ O ₃ may be 0%.

In the optical glass of this embodiment, the upper limit of the content of indium trioxide (In ₂ O ₃ ) is preferably 3%, and further preferably 2.5%, 2.0%, 1.5%, 1.0%, 0.5%, 0.1 %. In addition, the lower limit of the content of In ₂ O ₃ is preferably 0%. In addition, the content of In ₂ O ₃ may be 0%.

In the optical glass of this embodiment, the upper limit of the content of scandium trioxide (Sc ₂ O ₃ ) is preferably 3%, and further preferably 2.5%, 2.0%, 1.5%, 1.0%, 0.5%, 0.1 %. In addition, the lower limit of the content of Sc ₂ O ₃ is preferably 0%. In addition, the content of Sc ₂ O ₃ may be 0%.

In the optical glass of the present embodiment, the upper limit of the content of hafnium dioxide (HfO ₂ ) is preferably 3%, and further preferably 2.5%, 2.0%, 1.5%, 1.0%, 0.5%, and 0.1%. In addition, the lower limit of the content of HfO ₂ is preferably 0%. In addition, the content of HfO ₂ may be 0%.

In addition, in the optical glass of this embodiment, the upper limit of the content of bismuth trioxide (Lu ₂ O ₃ ) is preferably 3%, and further preferably 2.5%, 2.0%, 1.5%, 1.0%, 0.5% , 0.1%. In addition, the lower limit of the content of Lu ₂ O ₃ is preferably 0%. In addition, the content of Lu ₂ O ₃ may be 0%.

In addition, in the optical glass of the present embodiment, the upper limit of the content of germanium dioxide (GeO ₂ ) is preferably 3%, and further preferably 2.5%, 2.0%, 1.5%, 1.0%, 0.5%, 0.1% . In addition, the lower limit of the content of GeO ₂ is preferably 0%. In addition, the content of GeO ₂ may be 0%.

In addition, in the optical glass of the present embodiment, the upper limit of the content of phosphorus pentoxide (P ₂ O ₅ ) is preferably 2%, and further preferably 1.5%, 1.0%, 0.5%, and 0.1%. In addition, the lower limit of the content of P ₂ O ₅ is preferably 0%. In addition, the content of P ₂ O ₅ may be 0%.

The optical glass of this embodiment is preferably mainly composed of the aforementioned components, and the total content of the aforementioned components is preferably greater than 95%, more preferably greater than 98.0%, even more preferably greater than 99.0%, and even more preferably greater than 99.5%.

In addition, in the optical glass of the present embodiment, the upper limit of the content of tellurium dioxide (TeO ₂ ) is preferably 3%, and further preferably 2.5%, 2.0%, 1.5%, 1.0%, 0.5%, 0.1% . In addition, the lower limit of the content of TeO ₂ is preferably 0%. In addition, the content of TeO ₂ may be 0%.

In addition, about Pb, As, Cd, Tl, Be, Se, U, Th, Ra, V, Cr, Mn, Fe, Co, Ni, Cu, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho , The contents of Er, Tm, Ce, and Sb and Sn are the same as the description of the glass composition in% of cations in the first embodiment.

In addition, the optical glass of the present embodiment is preferably basically composed of the above-mentioned components, but it may contain other components within a range that does not hinder the operation and effects of the present invention. In addition, in the present invention, the inclusion of unavoidable impurities is not excluded.

In addition, the glass composition of the optical glass of this embodiment can be quantified by a method such as ICP-AES. The analysis value obtained by ICP-AES may include, for example, a measurement error of about ±5% of the analysis value. In addition, in the present specification and the present invention, the content of the constituent components of the glass is 0%, not included, and not introduced means that the constituent components are not substantially included, meaning that the content of the constituent components is below the level of impurities.

The characteristics (optical characteristics, glass transition temperature (Tg), light transmittance of glass, specific gravity of glass and liquidus temperature) of the optical glass of this embodiment are the same as those described in the first embodiment. Therefore, the description is omitted in this embodiment.

Manufacturing of optical glass

The optical glass of the above-mentioned two embodiments may be prepared according to a known glass manufacturing method by mixing raw materials so as to have the above-mentioned predetermined composition. For example, a plurality of compounds are blended and thoroughly mixed to form a batch raw material, and the batch raw material is placed in a platinum crucible and rough melted. The molten material obtained by rough melting is quenched and pulverized to produce broken glass. Further, the cullet produced in this manner is mixed, put in a platinum crucible, heated, and remelted to make molten glass, which is further clarified and homogenized, and then the molten glass is molded and slowly cooled to obtain optical glass. The molding of the molten glass only needs to use a well-known method.

In addition, the raw material (glass raw material) of each component in the glass is not particularly limited, and examples thereof include oxides, carbonates, nitrates, hydroxides, boric acid, boric anhydride, and silicon oxide of each metal.

Manufacturing of optical elements, etc.

To use the optical glass of the above two embodiments to make optical elements, only It is sufficient to apply a well-known method. For example, the optical glass of the present invention is melted and shaped into a plate-shaped glass material, the plate-shaped glass material is subdivided into a predetermined volume, and then the subdivided glass is ground to produce a glass material for precision press molding (precision press) Preforms for molding). Alternatively, the optical glass of the present invention is continuously molded from a molten state into a glass block of a predetermined volume to produce a glass material for precision press molding. Next, the glass material for precision press molding (preform for precision press molding) is heated and precision press molded to produce an optical element.

Depending on the purpose of use, the optical function surface of the manufactured optical element may be coated with an anti-reflection film, a total reflection film, or the like.

As the optical element, various lenses such as spherical lenses, aspherical lenses, microlenses, lens arrays, prisms, diffraction gratings, etc. can be exemplified.

Of course, although the embodiments of the present invention have been described above, the present invention is not limited to such embodiments, and can be implemented in plural ways without departing from the gist of the present invention.

In addition, in this specification, "optical glass" is a glass composition containing a plurality of metal oxides, regardless of the shape (bulk, plate, sphere, etc.) and application (material for optical element, optical element, etc.), Used as a general term.

In addition, in the present specification, the glass composition of the optical glass has been described in terms of cation% and mass %, but each of the display methods can be changed from each other by a conversion method such as described below.

As a result of quantitative analysis of the glass composition, the glass component is expressed on the basis of oxides, and the content of the glass component may be expressed in mass %. Such a composition representation can be expressed as a cation% or an anion% converted by the following method, for example.

The oxide composed of cation A and oxygen is expressed as A _m O _n . m and n are integers determined by stoichiometry, respectively. For example, B ³⁺ is expressed on the basis of oxide as B ₂ O ₃ , m=2, n=3, Si ^{4+ is} expressed as SiO ₂ , m=1, n=2.

First, the content of A _m O _n is expressed in mass%, the molecular weight divided by A _m O _n, and then multiplied by m. Set this value to P. Then sum up P for all glass components. When the sum of P is ΣP, the value of normalizing the P value of each glass component so that ΣP becomes 100% is the content of A ^s+ expressed in% of cations. Here, s is 2n/m.

In addition, clarification of trace additives such as Sb ₂ O ₃ may not be included in ΣP. In this case, the content of Sb ₂ O ₃ is set as the added content. That is, the total content of components other than Sb ₂ O ₃ is set to 100%, and the content of Sb ₂ O ₃ is expressed as a value relative to 100%.

In addition, the molecular weight of the oxide corresponds to the chemical formula weight of the oxide. The molecular weight of the oxide may be calculated using, for example, a value expressed as the third decimal place by rounding the fourth decimal place. In addition, for several glass components and additives, the molecular weights expressed on the basis of oxides are shown in Table 5 below.

[table 5]

[Example]

Hereinafter, the present invention will be described in more detail by examples, but the present invention is not limited to these examples.

(Example 1)

Tables 1A to 3A and Tables 1B to 3B show the glass compositions and characteristic values of optical glasses (Samples 1 to 24) of Examples of the present invention.

Here, Tables 1A to 3A are represented by cation %, and Tables 1B to 3B are represented by mass% of the glass composition of samples 1 to 24. That is, in Tables 1A to 3A and Tables 1B to 3B, the method of representing the glass composition is different, but the optical glass with the same sample number means the same optical glass with the same composition. Therefore, Table 1A ~3A and Tables 1B~3B show substantially the same optical glass and its results. Therefore, unless otherwise specified below, they are collectively referred to as "Tables 1 to 3".

In addition, in Tables 1A to 3A, the glass composition is expressed in terms of cation %, and all of the anion components are O ^2- . That is, the contents of O ^2- of the compositions described in Tables 1A to 3A are all 100 anion %.

In addition, these optical glasses were produced according to the following procedures, and various evaluations were performed.

[Melting and molding of optical glass]

Prepare oxides, hydroxides, carbonates, and nitrates corresponding to the constituent components of the glass as raw materials, and weigh and mix the above raw materials so that the glass composition of the obtained optical glass becomes each composition shown in Tables 1 to 3. To fully mix the raw materials. The obtained prepared raw material (batch raw material) was put into a platinum crucible, and put together with the crucible in an electric furnace set at 1250 to 1350°C according to the meltability of the raw material, and stirred while melting for 120 to 180 minutes. Seek homogenization and deaeration (clarification). Thereafter, the platinum crucible was tilted and the molten glass was cast into the preheated mold. The mold is preheated by placing the mold in an electric furnace with the temperature set to a temperature near the glass transition temperature (Tg) for 5 to 10 minutes, and the mold is taken out of the electric furnace for use when casting molten glass. In order to prevent the shape of the cast glass from being deformed, the glass is immediately transferred to the slow cooling furnace after the glass is left in the casting mold for a few seconds to several tens of seconds, and the temperature is set to the slow cooling of the temperature near the glass transition temperature Tg Annealing was carried out in the furnace for about 1 hour, and then slowly cooled to room temperature to obtain each optical glass (samples 1 to 24). In addition, all sample preparation was performed in an atmospheric environment.

Observation of the optical glass thus obtained revealed no crystals Precipitation of the body, bubbles, streaks, and melting residue of the raw materials confirmed that the optical glass with high homogeneity was obtained.

[Evaluation of optical glass]

The obtained optical glass (samples 1 to 24) was confirmed for the glass composition by the following method, and the refractive index (nd), Abbe number (νd), glass transition temperature (Tg), specific gravity (d), and coloring were evaluated. Degree (λ5), coloring degree (λ80), liquidus temperature and meltability.

[1] Confirmation of glass composition

An appropriate amount of each optical glass obtained in the above manner was selected, subjected to acid treatment and alkali treatment, and the content of each component was quantitatively determined by inductively coupled plasma atomic emission spectrometry (ICP-AES method). The oxide compositions of the samples shown in 1 to 3 are the same.

[2] Refractive index (nd) and Abbe number (νd)

In order to obtain a glass that has a shape that can sufficiently anneal a sample (for example, a square of 40 mm×40 mm or less and a thickness of 25 mm or less), and is sufficient to produce the size of 珜鏜, which will be described later, the optical fiber that is slowly cooled to room temperature is cut. Glass, so that the temperature of the glass can follow the rate of temperature increase (for example, 40 to 50°C/hour) to a temperature between the glass transition temperature Tg and (Tg + 30°C), and maintain for 90 minutes to 180 minutes. The stress in the glass is removed, slow cooling is carried out at a cooling rate of -30°C/hour for 4 hours, and then it is left to cool to obtain optical glass, and the optical glass is processed to produce 珜鏡, according to the standard of the Japan Optical Glass Industry Association The refractive index measurement method is to measure the refractive index (nd), the refractive index (nF), and the refractive index (nc) using a precision spectrometer GMR-1 (trade name) manufactured by Shimadzu Instruments Manufacturing Company. Then, the Abbe number (νd) is calculated using the measured values of the refractive index (nd), the refractive index (nF), and the refractive index (nc). The results are shown in Tables 1 to 3.

[3] Glass transition temperature (Tg)

The measurement was performed using a thermomechanical analyzer manufactured by Rigaku Corporation at a temperature increase rate of 4°C/minute. The results are shown in Tables 1 to 3.

[4] Specific gravity (d)

The determination was made by Archimedes method. The results are shown in Tables 1 to 3.

[5]Coloring degree (λ5), coloring degree (λ80)

The optical glass sample was processed to prepare a plate-shaped glass sample having a thickness of 10 mm±0.1 mm with both surfaces parallel to each other and optically polished flatly. For the light incident from the vertical direction on the polished surface of the plate-shaped glass sample, the spectral transmittance including the surface reflection loss was measured using a spectrophotometer in the wavelength range of 280 nm to 700 nm, and the spectral transmittance (external transmittance) was 5% and The wavelength of 80% is regarded as the coloring degree (λ5) and the coloring degree (λ80), respectively. The smaller the values of λ5 and λ80, the less the color of the glass. The results are shown in Tables 1 to 3.

[6] Liquidus temperature

After putting 10cc (10ml) of glass in a platinum crucible and melting it at 1250°C to 1350°C for 20 to 30 minutes, it is cooled to below the glass transition temperature (Tg), and the glass and platinum crucible are placed together at a predetermined temperature The melting furnace is maintained for 2 hours. Keeping the temperature above 1000°C and the step size of 5°C or 10°C, the lowest temperature at which no crystals precipitate after 2 hours of holding is defined as the liquidus temperature. The results are shown in Tables 1 to 3.

[7] Meltability

The batch raw materials were prepared in such a manner that glass having the composition described in Tables 1 to 3 was obtained, and the raw materials were placed in a platinum crucible. The amount of raw material put into the crucible is the amount of glass melt which becomes 10 ml at the time of melting. Put the crucible with raw materials into Inside the glass melting furnace heated at 1160°C, the raw materials were melted for 15 minutes in the atmosphere. After 15 minutes, the crucible was taken out of the glass melting furnace, and the glass melt was left to cool to room temperature to obtain glass. The obtained glass was visually observed for melting residues, and as a result, no melting residues of the raw materials were found in any composition.

[Table 3A]

[Table 1B]

[Table 2B]

[Table 3B]

As shown in Tables 1 to 3, it can be confirmed that although the content of tantalum oxide (Ta ₂ O ₅ , corresponding to Ta ⁵⁺ ) is reduced, it is excellent in thermal stability, low-temperature softening property, and meltability, and can achieve the required Optical characteristics.

(Example 2)

Using various optical glasses obtained in Example 1, a preform for precision press molding was produced by a known method. The obtained preform is heated and softened in a nitrogen environment, and precision compression molding is performed using a compression molding die to shape the optical glass into an aspheric lens shape.

After that, the molded optical glass was taken out from the press mold, annealed and centered and edging to produce an aspheric lens composed of various optical glasses.

No defects such as white turbidity, bubbles, and scratches were found on the surface of the aspheric lens produced in this way.

(Comparative example 1)

Next, Table 4A and Table 4B show the composition of the optical glass (samples 25 to 29) of the comparative example of the present invention. In addition, Table 4A shows each glass composition as a cation %, Table 4B shows each glass composition as a mass %, and the optical glass with the same sample number means the same optical glass with the same composition. In addition, the content of O ^2- of the composition described in Table 4A is 100% of anion. In addition, unless otherwise specified, Tables 4A and 4B are collectively referred to as "Table 4".

In addition, sample 25 in Table 4 is an optical glass corresponding to the glass shown in Example 3 of Patent Document 1 (Japanese Patent Laid-Open No. 6-305769), and sample 26 is a patent glass 2 (Japanese Patent Laid-Open No. 8-026765) The optical glass corresponding to the glass shown in Example 9 of Example 1, the sample 27 is the optical glass corresponding to the glass shown in Example 3 of Patent Document 3 (Japanese Patent Laid-Open No. 2005-272194), and the sample 28 is corresponding to Patent Document 4 (Japanese Patent Laid-Open No. 56-54251) The optical glass corresponding to the glass described as No. 1 in Table 1, and sample 29 is the glass shown in Example 26 of Patent Document 5 (Japanese Patent Laid-Open No. 2002-249337) Corresponding optical glass.

Here, as Comparative Example 1, the optical glass shown in Table 4 was subjected to a meltability evaluation experiment under the following conditions. In addition, the conditions not described below are the same conditions as in Example 1.

First, in order to obtain glass having each composition described in Table 4, 200 g of a batch material corresponding to each sample was prepared. Then, the obtained batch raw materials are put into respective platinum crucibles, and heated and melted at a predetermined temperature for a fixed time.

Samples 25 to 27 were heated and melted at 1160°C for 15 minutes. In the same manner as in the evaluation of the meltability of Example 1, the crucible was taken out of the heating furnace after 15 minutes had passed, left to cool to room temperature, and the melt in the crucible was taken out for observation.

In addition, the sample 28 and the sample 29 were heated and melted at 1300°C for 2 hours with stirring. After 2 hours passed, the crucible was taken out of the heating furnace, left to cool to room temperature, and the melt in the crucible was taken out for observation.

[Table 4A]

[Table 4B]

As a result of the above-mentioned evaluation experiment, in Sample 25 and Sample 26, a large amount of molten residue (unmelted material) of the raw material was found inside the extracted melt. The cation ratio (γ) = [Nb ⁵⁺ /(Nb ⁵⁺ +Ta ⁵⁺ )] of these samples is less than 0.5 and the mass ratio (γw) = [Nb ₂ O ₅ /(Nb ₂ O ₅ +Ta ₂ O ₅ )] Less than 2/3, especially sample 25, the value (L') is also less than -0.1, and it is confirmed that the meltability is lower than the samples of the examples of the present invention. In addition, for sample 25 and sample 26, the temperature in the heating furnace was increased to 1210° C. The same experiment was conducted again, but a large amount of molten residue (unmelted material) of the raw material was still found inside.

As a result of the above-mentioned evaluation experiment, in Sample 27, a large amount of molten residue (unmelted material) of the raw material was found inside the extracted melt. The total content (HR) of such sample 27 = [Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Ta ⁵⁺ +Bi ³⁺ ] is 7 cation% or more, which is more than 0.30 than [HR'/RE'], It can be confirmed that the meltability is lower than that of the samples of Examples of the present invention.

In addition, in the sample 28, it was confirmed that crystals were precipitated in the melted material taken out to produce white turbidity. Such a sample 28 has a cation ratio (β)=[La ³⁺ /(La ³⁺ +Gd ³⁺ +Y ³⁺ +Yb ³⁺ )] and a mass ratio βw=[La ₂ O ₃ /(La ₂ O ₃ +Gd ₂ O ₃ +Y ₂ O ₃ +Yb ₂ O ₃ )] are 1 (including only La, Gd, Y, and Yb La), it can be confirmed that the glass is compared with the samples of the examples of the present invention Has low thermal stability.

As a result of the above evaluation experiment, in Sample 29, a large amount of molten residue (unmelted material) of the raw material was found inside the melted material taken out. The value (L) of such a sample 29 is less than 24, and the value (L') is less than -0.10. It can be confirmed that the meltability is lower than the samples of the examples of the present invention.

Claims (9)

An optical glass, which is an oxide glass, expressed as% of cation, the total content of B ³⁺ , Si ⁴⁺ , La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ [B ³⁺ +Si ^{4 +} +La ³⁺ +Gd ³⁺ +Y ³⁺ +Yb ³⁺ ] is 65% or more; the total content of La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ is relative to B ³⁺ and Si ⁴⁺ The cation ratio (α) of the total content of Al ³⁺ = [(La ³⁺ +Gd ³⁺ +Y ³⁺ +Yb ³⁺ )/(B ³⁺ +Si ⁴⁺ +Al ³⁺ )] is 0.30~ 0.70; with respect to the content of La ³⁺ La ^3+, the total cation content of Gd ^3+, Y ³⁺ and Yb ³⁺ ratio ^{(β) = [La 3+ /} (La 3+ + Gd 3+ + Y 3 ⁺ +Yb ³⁺ )] less than 1 and excluding 0; the total content of Nb ⁵⁺ , Ti ⁴⁺ , W ⁶⁺ , Ta ⁵⁺ and Bi ³⁺ [Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ +Ta ⁵⁺ + Bi ^3+] is less than 7%; Nb ⁵⁺ content with respect to the total Nb ⁵⁺ and Ta ⁵⁺ content of the cation ratio of ^{(γ) = [Nb 5+ /} (Nb 5+ + Ta 5+)] 0.5 or more; the sum of 6 times the content of Li ⁺ and 2 times the content of Zn ²⁺ minus the value of the content of Si ⁴⁺ (L) = [(6×Li ⁺ )+(2×Zn ²⁺ ) -Si ⁴⁺ ] is 24 or more; Abbe number (νd) is 43.5~47; relative to this Abbe number (νd), the refractive index (nd) satisfies the following formula (1): Formula (1) nd

2.25-0.01×νd. The optical glass as described in item 1 of the patent application scope, wherein the content of Zr ⁴⁺ is 0.1 to 10 cationic %. The optical glass as described in item 1 or 2 of the patent scope, in which the total content of B ³⁺ , Si ⁴⁺ , La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ [B ³⁺ +Si ⁴⁺ +La ³⁺ +Gd ³⁺ +Y ³⁺ +Yb ³⁺ ] is 84.0% or less. An optical glass containing B ₂ O ₃ , La ₂ O ₃ and Nb ₂ O ₅ as essential components; the ratio of value (RE') to value (NWF') [RE'/NWF'] is 0.30~0.70; value (HR ') ratio (the value RE) with respect to the' [HR '/ RE'] is 0.30 or less; the content of La ₂ O ₃ with respect to _{La 2 O 3, Gd 2 O} 3, Y 2 O 3 and Yb ₂ O The mass ratio of the total content of ₃ (βw) = [La ₂ O ₃ /(La ₂ O ₃ +Gd ₂ O ₃ +Y ₂ O ₃ +Yb ₂ O ₃ )] less than 1 and does not include 0; Nb ₂ O ₅ The mass ratio of the content relative to the total content of Nb ₂ O ₅ and Ta ₂ O ₅ (γw)=[Nb ₂ O ₅ /(Nb ₂ O ₅ +Ta ₂ O ₅ )] is 2/3 or more; the value (L ') is -0.10 or more; Abbe's number (νd) is 43.5~47; with respect to this Abbe's number (νd), the refractive index (nd) satisfies the following formula (1): Formula (1)nd

2.25-0.01×νd: In the formula: B ₂ O ₃ , SiO ₂ , Al ₂ O ₃ , La ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ , Yb ₂ O ₃ , Nb ₂ O ₅ , TiO ₂ , The molecular weights of WO ₃ , Bi ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, and ZnO are expressed as M(B ₂ O ₃ ), M(SiO ₂ ), M(Al ₂ O ₃ ), M (La ₂ O ₃ ), M(Gd ₂ O ₃ ), M(Y ₂ O ₃ ), M(Yb ₂ O ₃ ), M(Nb ₂ O ₅ ), M(TiO ₂ ), M(WO ₃ ) , M(Bi ₂ O ₃ ), M(Li ₂ O), M(Na ₂ O), M(K ₂ O) and M(ZnO); the content of each of the above components is expressed in mass% value of the ratio of the case of containing the component represented by: the value (NWF ') is twice the value of the content of B ₂ O ₃ is divided by M (B ₂ O ₃₎ value, the value of the content of SiO ₂ The value divided by the value of M(SiO ₂ ) and the value of dividing the value of Al ₂ O ₃ twice by the value of M(Al ₂ O ₃ ); the value (RE′) is the value of La ₂ O ₃ Divide twice the value of the content by the value of M(La ₂ O ₃ ), divide twice the value of the content of Gd ₂ O ₃ by the value of M(Gd ₂ O ₃ ), and divide the value of Y ₂ O ₃ by divided by twice the value of M (Y ₂ O _3), and twice the value of the content of Yb ₂ O ₃ is divided by the value of M (Yb ₂ O ₃₎ a sum of values; this value (HR ') is Divide twice the value of the content of Nb ₂ O ₅ by the value of M(Nb ₂ O ₅ ), divide the value of the content of TiO ₂ by the value of M(TiO ₂ ), and divide the value of the content of WO ₃ by and 2 times the value of the content of Bi ₂ O ₃ value of M (WO ₃₎ is divided by M (Bi ₂ O ₃₎ a sum of values; this value (L ') to the value of the content of Li ₂ O 12 times the value of M(Li ₂ O), divide 4 times the value of Na ₂ O content by the value of M(Na ₂ O), divide 2 times the value of K ₂ O content by M The value of (K ₂ O) and the total value of dividing the value of ZnO by 2 times the value of M(ZnO) minus the value of dividing by 2 times the value of SiO ₂ by the value of M(SiO ₂ ), the value of the sum of the value twice the value of the content of Al ₂ O ₃ is divided by M (Al ₂ O ₃₎ and the numerical value of the content of B ₂ O ₃ is divided by M (B ₂ O ₃₎ a. The optical glass as described in item 4 of the patent application scope, wherein the content of ZrO ₂ is 0.1 to 15% by mass. The optical glass as described in item 4 or 5 of the patent application, wherein the value (NWF') is 0.80 or less. The optical glass according to any one of items 1, 2, 4, and 5 of the patent application scope, wherein the content of Sb ₂ O ₃ is less than 1% by mass. An optical element composed of the optical glass described in any one of patent application items 1 to 7. A preform for precision press forming is composed of the optical glass described in any one of the items 1 to 7 of the patent application range.

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