TW201623174A - Glass, glass material for press molding, optical element blank, and optical element - Google Patents

Abstract

An embodiment of the present invention relates to a glass which is an oxide glass in which, in terms of cation %, the total content of B3+ and Si4+ is 43-65%, the total content of La3+, Y3+, Gd3+, and Yb3+ is 25-50%, the total content of Nb5+, Ti4+, Ta5+, and W6+ is 3-12%, the Zr4+ content is 2-8%, the cation ratio of the total content of B3+ and Si4+ with respect to the total content of La3+, Y3+, Gd3+, and Yb3+ is 0.70-1.75, the cation ratio of the total content of B3+ and Si4+ with respect to the total content of Nb5+, Ti4+, Ta5+, and W6+ is 9.00 or less, the cation ratio of the Zn2+ content with respect to the total content of La3+, Y3+, Gd3+, and Yb3+ is less than 0.2, the cation ratio of the La3+ content with respect to the total content of La3+, Y3+, Gd3+, and Yb3+ is 0.50-0.95, the cation ratio of the Y3+ content with respect to the total content of La3+, Y3+, Gd3+, and Yb3+ is 0.10-0.50, the cation ratio of the Gd3+ content with respect to the total content of La3+, Y3+, Gd3+, and Yb3+ is 0.10 or less, the cation ratio of the Nb5+ content with respect to the total content of Nb5+, Ti4+, and W6+ is 0.80 or greater, the cation ratio of the Ta5+ content with respect to the total content of Nb5+, Ti4+, Ta5+, and W6+ is 0.20 or less, the Abbe number of the oxide glass is in the range of 39.5-41.5, and the refractive index nd of the oxide glass satisfies the relationship nd ≥ 2.0927-0.0058 x [nu]d with respect to the Abbe number νd.

Description

Glass, glass material for press molding, optical component blanks and optical components

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

A lens composed of a high refractive index low-dispersion glass is combined with a lens made of ultra-low dispersion glass to form a cemented lens, whereby chromatic aberration can be corrected and the optical system can be made compact. Therefore, the high refractive index low dispersion glass plays an important role as an optical element constituting a projection optical system such as an imaging optical system or a projector. Such high refractive index low dispersion glass is described, for example, in Patent Documents 1 to 20.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Laid-Open Patent Publication No. 2007-063071.

Patent Document 2: Japanese Laid-Open Patent Publication No. 2007-230835.

Patent Document 3: Japanese Laid-Open Patent Publication No. 2007-249112.

Patent Document 4: Japanese Laid-Open Patent Publication No. 2007-261826.

Patent Document 5: Japanese Laid-Open Patent Publication No. 2003-267748.

Patent Document 6: Japanese Laid-Open Patent Publication No. 2009-203083.

Patent Document 7: Japanese Laid-Open Patent Publication No. 2011-230992.

Patent Document 8: Japanese Laid-Open Patent Publication No. 2012-025638.

Patent Document 9: Japanese Laid-Open Patent Publication No. SHO 54-090218.

Patent Document 10: Japanese Laid-Open Patent Publication No. SHO 56-160340.

Patent Document 11: Japanese Laid-Open Patent Publication No. 2001-348244.

Patent Document 12: Japanese Laid-Open Patent Publication No. 2008-001551.

Patent Document 13: Japanese Laid-Open Patent Publication No. 2013-536791.

Patent Document 14: WO10/053214.

Patent Document 15: Japanese Laid-Open Patent Publication No. 2012-180278.

Patent Document 16: Japanese Laid-Open Patent Publication No. 2012-236754.

Patent Document 17: Japanese Laid-Open Patent Publication No. 2014-084235.

Patent Document 18: Japanese Laid-Open Patent Publication No. 2014-062025.

Patent Document 19: Japanese Laid-Open Patent Publication No. 2014-062026.

Patent Document 20: Japanese Laid-Open Patent Publication No. 2011-93780.

For the glass for optical elements, an optical characteristic map (also referred to as an Abbe chart) is widely used in order to display the distribution of optical characteristics. The optical characteristic map is produced in such a manner that the horizontal axis is the Abbe number (νd), the vertical axis is the refractive index (nd), and the Abbe number (νd) is increased from the right side to the left side of the horizontal axis, and the refractive index is from the vertical axis. The bottom direction increases above. In addition, unless otherwise specified, the refractive index and the Abbe number are referred to as the refractive index (nd) of the d-line (wavelength: 587.56 nm) and the d-line of the 氦 (wavelength: 587.56 nm). Number (νd).

In the optical characteristic diagram, the optical characteristics of the high refractive index low dispersion glass (high nd high νd glass) generally show a distribution that rises to the right. That is, the refractive index increases as the Abbe number decreases, and the refractive index decreases as the Abbe number increases. The reason is considered as follows.

The high refractive index low dispersion glass mostly contains rare earth oxides such as boron oxide and cerium oxide. In such a glass, in order to increase the refractive index without lowering the Abbe number, it is necessary to increase the content of the rare earth oxide. However, when the content of the rare earth oxide is increased in the high refractive index low dispersion glass of the prior art, the thermal stability of the glass is lowered, and the glass exhibits a tendency to devitrification during the process of producing the glass. Therefore, in the prior art high refractive index low dispersion glass, it is difficult to increase the Abbe number and the refractive index together while suppressing devitrification of the glass in order to be used as an optical element material. This is considered to be the reason why the high-refractive-index low-dispersion glass of the prior art shows the above-described distribution in the optical characteristic diagram.

On the other hand, in the design of an optical system, a glass having a high refractive index and a large Abbe number (low dispersion) is an optical element which is extremely effective for correcting chromatic aberration, high function of an optical system, and compactness. material. Therefore, it is very important to set a straight line that rises to the right on the optical characteristic diagram, and to provide a glass having a higher refractive index than a straight line on the straight line (in the figure, a region on the left side of the straight line).

From the above viewpoints, the Abbe number (νd) is 39.5 to 41.5 and the refractive index (nd) is a glass having a value obtained by using the value of 2.0927-0.0058 × νd for the Abbe number, that is, satisfying nd A glass having a relationship of 2.0927-0.0058 x νd is a high refractive index low dispersion glass useful in an optical system.

On the other hand, among the glasses described in Patent Documents 1 to 20, the Abbe number (νd) ranges from 39.5 to 41.5 and satisfies nd. The high refractive index low dispersion glass having a relationship of 2.0927 to 0.0058 x νd contains any one of bismuth (Gd) and strontium (Ta). However, both Gd and Ta are rare and high-value elements. Since demand in various industrial fields has increased in recent years, supply is insufficient relative to market demand. Therefore, from the viewpoint of stably supplying the high refractive index low dispersion glass, it is desirable to reduce the content of Gd and Ta in the high refractive index low dispersion glass.

On the other hand, in the glass composition of the prior art high refractive index low dispersion glass, when it is desired to maintain optical properties and thermal stability while reducing the contents of Gd and Ta, there is light absorption on the short wavelength side of the glass. The wavelength of the end length is increased, and the transmittance of ultraviolet light is greatly lowered.

However, in order to correct chromatic aberration, a method is known in which a plurality of lenses are produced using glass having different optical characteristics, and these lenses are bonded together to form a cemented lens. In the process of making a cemented lens, in order to bond the lenses to each other, an ultraviolet curing type adhesive is usually used. The details are as follows. An ultraviolet curable adhesive is applied to the surface on which the lenses are bonded to each other to bond the lenses. At this time, an extremely thin coating layer of an ultraviolet curable adhesive can usually be formed between the lenses. Next, the coating layer is irradiated with ultraviolet rays by a lens to cure the ultraviolet curable adhesive. Therefore, when the ultraviolet transmittance of the lens is low, ultraviolet rays having a sufficient luminous flux cannot reach the coating layer by the lens, and the curing becomes insufficient. Or it takes a long time to cure.

Further, the same applies to the case where the lens is adhered and fixed to the lens barrel or the like by using an ultraviolet curable adhesive, and when the ultraviolet transmittance of the lens is low, the curing becomes insufficient or the curing takes a long time.

Therefore, in order to make the glass having the transmittance characteristic suitable for the optical system, it is desirable to suppress the long wavelength of the light absorption end on the short-wavelength side of the glass.

An object of one embodiment of the present invention is to provide a glass having an Abbe number (νd) of 39.5 to 41.5 and satisfying nd With a relationship of 2.0927-0.0058 × νd, the glass can be stably supplied and is suitable for fabricating an optical system.

An embodiment of the present invention relates to a glass (hereinafter referred to as "glass A"), wherein the glass is an oxide glass, wherein the total content of B ³⁺ and Si ⁴⁺ is 43 to 65% in terms of cationic %; The total content of ³⁺ , Y ³⁺ , Gd ³⁺ and Yb ³⁺ is 25 to 50%; the total content of Nb ⁵⁺ , Ti ⁴⁺ , Ta ⁵⁺ and W ⁶⁺ is 3 to 12%; Zr ⁴⁺ The content of 2 to 8%; the total content of B ³⁺ and Si ⁴⁺ relative to the total content of La ³⁺ , Y ³⁺ , Gd ³⁺ and Yb ³⁺ cation ratio {(B ³⁺ +Si ⁴⁺ ) / (La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ³⁺ )} is 0.70 to 1.75; the total content of B ³⁺ and Si ⁴⁺ is relative to Nb ⁵⁺ , Ti ⁴⁺ , Ta ⁵⁺ and W The cation ratio of the total content of ⁶⁺ is {(B ³⁺ +Si ⁴⁺ )/(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ )} is 9.00 or less; the content of Zn ²⁺ is relative to La ³ The cation ratio of the total content of ⁺ , Y ³⁺ , Gd ³⁺ and Yb ³⁺ is {Zn ²⁺ /(La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ³⁺ )} is less than 0.2; La ³⁺ The cation ratio of {La ³⁺ /(La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ³⁺ )} to the total content of La ³⁺ , Y ³⁺ , Gd ³⁺ and Yb ³⁺ is 0.50~ Cation ratio of 0.95; Y ³⁺ content relative to the total content of La ³⁺ , Y ³⁺ , Gd ³⁺ and Yb ³⁺ {Y ³⁺ /(La ³⁺ +Y ³⁺ + Gd ³⁺ + Yb ^3+)} is 0.10 to 0.50; Gd ³⁺ content with respect to the La ^3+, Y ^3+, Gd ³⁺ cations and the total content ratio of Yb ³⁺ {Gd ³⁺ / (La ^{3+ + Y 3+ + Gd 3+ +} Yb 3+)} is 0.10 or less; the content of Nb ⁵⁺ respect Nb ^5+, Ti ⁴⁺ cation and the total content ratio of W ⁶⁺ {Nb ⁵⁺ / ( ^{nb 5+ + Ti 4+ + W 6+} )} is 0.80 or more; Ta ⁵⁺ content with respect to the nb ^5+, cationic Ti ^4+, Ta ^5+, and the total content of W ⁶⁺ ratio {Ta ⁵⁺ / (Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ )} is 0.2 or less; the Abbe number (νd) ranges from 39.5 to 41.5, and the refractive index (nd) and the Abbe number (νd) satisfy Description (1): nd 2.0927-0.0058×νd.

Further, an embodiment of the present invention relates to a glass (hereinafter referred to as "glass B") which is an oxide glass in which the total content of B ₂ O ₃ and SiO ₂ is 17.5 to 35% in mass%. The total content of La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ and Yb ₂ O ₃ is 45 to 70%; the total content of Nb ₂ O ₅ , TiO ₂ , Ta ₂ O ₅ and WO ₃ is 3~ 16%; the content of ZrO ₂ is 2 to 10%; the mass ratio of the total content of B ₂ O ₃ and SiO _{2 to} the total content of 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 + Y ₂ O ₃ + Gd ₂ O ₃ + Yb ₂ O ₃ )} is 0.2 to 0.5; the total content of B ₂ O ₃ and SiO ₂ is relative to Mass ratio of total content of Nb ₂ O ₅ , TiO ₂ , Ta ₂ O ₅ and WO ₃ {(B ₂ O ₃ + SiO ₂ ) / (Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ + WO ₃ )} 2.8 or less; mass ratio of ZnO content to total content of La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ and Yb ₂ O ₃ {ZnO/(La ₂ O ₃ +Y ₂ O ₃ +Gd _{2 O 3 + Yb 2 O 3)} } is less than 0.10; the content of La ₂ O ₃ with respect to _{La 2 O 3, Y 2 O} 3, Gd mass total content ₂ O ₃ and Yb ₂ O ₃ ratio {La ₂ O ₃ /(La ₂ O ₃ +Y ₂ O ₃ +Gd ₂ O ₃ +Yb ₂ O ₃ )} is 0 .55 ~ 0.98; Y ₂ O ₃ content with respect to _{La 2 O 3, Y 2 O} 3, Gd total content mass ₂ O ₃ and Yb ₂ O ₃ ratio of _{{Y 2 O 3 / (La} 2 O 3 + Y ₂ O ₃ +Gd ₂ O ₃ +Yb ₂ O ₃ )} is 0.02 to 0.45; the content of Gd ₂ O ₃ is relative to the total of La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ and Yb ₂ O ₃ The mass ratio of the content is {Gd ₂ O ₃ /(La ₂ O ₃ +Y ₂ O ₃ +Gd ₂ O ₃ +Yb ₂ O ₃ )} is 0.10 or less; the content of Nb ₂ O ₅ is relative to Nb ₂ O ₅ , TiO The mass ratio of the total content of ₂ and WO ₃ is {Nb ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ )} is 0.81 or more; the content of Ta ₂ O ₅ is relative to Nb ₂ O ₅ , TiO ₂ , Ta The mass ratio of the total content of ₂ O ₅ and WO ₃ is {Ta ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +Ta ₂ O ₅ +WO ₃ )} is 0.3 or less; the Abbe number (νd) is 39.5. ~41.5, and the refractive index (nd) and the Abbe number (νd) satisfy the above formula (1).

Glass A has an Abbe number (νd) ranging from 39.5 to 41.5 and satisfies nd a glass having a relationship of 2.0927-0.0058×νd, wherein the total content of various components including Gd ³⁺ (ie, La ³⁺ , Y ³⁺ , Gd ³⁺ , Yb ³⁺ ) and various components including Ta ⁵⁺ ( In other words, the total content of Nb ⁵⁺ , Ti ⁴⁺ , Ta ⁵⁺ , and W ⁶ +) satisfies the above-described cation ratio in which the denominator or the molecule contains Gd ³⁺ and Ta ⁵⁺ in the above range. Therefore, the proportion of Gd and Ta is reduced in the glass composition. By adjusting the composition satisfying the above-described content, total content, and cation ratio in the composition satisfying such a total content and the cation ratio, the glass can be suppressed while achieving high thermal stability (non-devitrification property). The long wavelength of the light absorption end on the short wavelength side.

Glass B has an Abbe number (νd) ranging from 39.5 to 41.5 and satisfies nd a glass having a relationship of 2.0927-0.0058×νd, wherein a total content of various components including Gd ₂ O ₃ (ie, La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ , Yb ₂ O ₃ ) and containing Ta ₂ The total content of various components of O ₅ (i.e., Nb ₂ O ₅ , TiO ₂ , Ta ₂ O ₅ , and WO ₃ ) satisfies the above-mentioned range in which the denominator or the molecule contains Gd ₂ O ₃ or Ta ₂ O ₅ . ratio. Therefore, the proportion of Gd and Ta is reduced in the glass composition. By adjusting the composition satisfying the above-described content, total content, and mass ratio in the composition satisfying such a total content and mass ratio, the glass can be suppressed while achieving high thermal stability (non-devitrification property). The long wavelength of the light absorption end on the short wavelength side.

According to an embodiment of the present invention, it is possible to provide a glass which has optical characteristics useful in an optical system, can be stably supplied, and has transmittance characteristics suitable for fabricating an optical system. Further, according to an embodiment of the present invention, it is possible to provide a glass material for press molding, an optical element blank, and an optical element which are made of the above glass.

1 is a photograph of a glass evaluated in Comparative Example 6.

The glass composition in the present invention can be quantified by a method such as ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry). The analysis value obtained by ICP-AES sometimes includes a measurement error of about ±5% of the analysis value. Further, in the present specification and the present invention, the content of the constituent component is 0%, and the inclusion or non-introduction means that the constituent component is not substantially contained, and the content of the constituent component is not more than the impurity level.

Regarding the numerical range, the (more) preferred lower limit and the (more preferred upper limit) are sometimes described below. In the table, the numerical value described below is better, and the numerical value described at the bottom is the best. Further, unless otherwise specified, the (better) preferred lower limit means that (more preferably) the above-described value is more or less, and the (more) preferred upper limit means (more preferably) the stated value or less. . The numerical value range can be arbitrarily combined with the numerical value of the column of the (more preferable lower limit) and the numerical value of the column of the (more preferable upper limit).

[Glass A]

The glass A according to an embodiment of the present invention is an oxide glass having the above glass composition, the Abbe number (νd) is in the range of 39.5 to 41.5, and the refractive index (nd) and the Abbe number (νd) satisfy the above formula. (1). The above glass A will be described in detail below.

In the present invention, the cationic component is represented by a cationic % The glass composition of the glass A. As is well known, the cation % means a percentage in which the total content of all the cation components contained in the glass is 100%.

Hereinafter, the content of the cationic component of the glass A and the total content (the total content) of the plurality of cationic components are represented by the cation % unless otherwise specified. Further, in the cation % expression, the ratio of the content of the cation components (including the total content of the plurality of cation components) is referred to as a cation ratio.

<glass composition>

B ³⁺ and Si ⁴⁺ are the network forming components of glass. When the total content of B ³⁺ and Si ⁴⁺ (B ³⁺ + Si ⁴⁺ ) is 43% or more, the thermal stability of the glass is improved, and crystallization of the glass in the production process can be suppressed. On the other hand, when the total content of B ³⁺ and Si ⁴⁺ is 65% or less, the decrease in the refractive index (nd) can be suppressed, and thus the glass having the above optical characteristics can be produced. Therefore, the range of the total content of B ³⁺ and Si ⁴⁺ in the above glass is set to 43 to 65%. A preferred lower limit and a preferred upper limit of the total content of B ³⁺ and Si ⁴⁺ are shown in Table 1 below.

La ³⁺ , Y ³⁺ , Gd ^{3+ ,} and Yb ³⁺ are components having an effect of increasing the refractive index while suppressing a decrease in the Abbe number (νd). Further, these components have an effect of improving the chemical durability, weather resistance, and glass transition temperature of the glass.

When the total content of La ³⁺ , Y ³⁺ , Gd ^{3+ ,} and Yb ³⁺ (La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ³⁺ ) is 25% or more, the refractive index (nd) can be suppressed. Since it is lowered, it is possible to produce a glass having the above optical characteristics. Further, it is also possible to suppress chemical durability and deterioration of weather resistance of the glass. In addition, when the glass transition temperature is lowered, the glass is easily broken (machineability is lowered) when the glass is machined (cut, cut, polished, polished, etc.), when La ³⁺ , Y ³⁺ , Gd ³⁺ When the total content of Yb ³⁺ is 25% or more, the decrease in the glass transition temperature can be suppressed, so that the machinability can be improved. On the other hand, when the total content of each component of La ³⁺ , Y ³⁺ , Gd ^{3+ ,} and Yb ³⁺ is 50% or less, the thermal stability of the glass can be improved, and thus the crystallization at the time of glass production can be suppressed. And reducing the melting residue of the raw material when the glass is melted. In addition, it is also possible to suppress an increase in the specific gravity. Therefore, in the above glass, the total content of La ³⁺ , Y ³⁺ , Gd ^{3+ ,} and Yb ^{3+ is} in the range of 25 to 50%. The lower limit and the preferred upper limit of the total content of La ³⁺ , Y ³⁺ , Gd ³⁺ and Yb ³⁺ are shown in Table 2 below.

Nb ⁵⁺ , Ti ⁴⁺ , Ta ^{5+ ,} and W ⁶⁺ are components having an effect of increasing the refractive index, and are contained in an appropriate amount to further improve the thermal stability of the glass. When the total content of Ti ⁴⁺ , Nb ⁵⁺ , Ta ^{5+ ,} and W ⁶⁺ (Nb ⁵⁺ + Ti ⁴⁺ + Ta ⁵⁺ + W ⁶⁺ ) is 3% or more, it is possible to maintain thermal stability while maintaining thermal stability. The above optical characteristics are achieved. On the other hand, when the total content of Nb ⁵⁺ , Ti ⁴⁺ , Ta ^{5+ ,} and W ⁶⁺ is 12% or less, it is possible to suppress a decrease in thermal stability and a decrease in Abbe number νd. Further, it is also possible to suppress an increase in the coloring degree (λ5) to be described later and increase the ultraviolet transmittance of the glass. Therefore, in the above glass, the total content of Nb ⁵⁺ , Ti ⁴⁺ , Ta ^{5+ ,} and W ⁶⁺ is set to be 3 to 12%. The lower limit and the preferred upper limit of the total content of Nb ⁵⁺ , Ti ⁴⁺ , Ta ⁵⁺ and W ⁶⁺ are shown in Table 3 below.

Zr ⁴⁺ is a component having an effect of increasing the refractive index, and has an effect of improving the thermal stability of the glass by being contained in an appropriate amount. In addition, Zr ⁴⁺ also has the effect of making the glass less susceptible to breakage during machining by increasing the glass transition temperature. In order to obtain these effects favorably, the content of Zr ⁴⁺ is set to 2% or more in the above glass. On the other hand, when the content of Zr ⁴⁺ is 8% or less, the thermal stability of the glass can be improved. Therefore, it is possible to suppress crystallization during the production of glass and to suppress the occurrence of melting residue when the glass is melted. Therefore, the range of the content of Zr ⁴⁺ in the above glass is set to 2 to 8%. A preferred lower limit and a preferred upper limit of the content of Zr ⁴⁺ are shown in Table 4 below.

In order to improve the thermal stability of the glass, the optical characteristics of the relationship between the refractive index (nd) and the Abbe number (νd) satisfying the above formula (1) are achieved while the Abbe number (νd) is 39.5 to 41.5, in the above glass. The cation ratio of the total content of B ³⁺ and Si ^{4+ to} the total content of La ³⁺ , Y ³⁺ , Gd ^{3+ ,} and Yb ³⁺ is {(B ³⁺ +Si ⁴⁺ )/(La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ³⁺ )} is set to 0.70~1.75. If the cation ratio ((B ³⁺ +Si ⁴⁺ )/(La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ³⁺ ))) is 0.70 or more, the thermal stability of the glass can be improved, and thus the glass can be suppressed. Destruction. In addition, it is also possible to suppress an increase in the specific gravity of the glass. When the specific gravity of the glass increases, the optical element made using the glass becomes heavy. As a result, the optical system in which the optical element is assembled becomes heavy. For example, when a heavy optical component is assembled in an auto-focusing camera, the power consumption when driving autofocus increases, and the battery is quickly consumed. From the viewpoint of reducing the weight of the optical element produced using the glass and the optical system in which the optical element is assembled, it is preferable to suppress an increase in the specific gravity of the glass. On the other hand, if the cation ratio {(B ³⁺ + Si ⁴⁺ ) / (La ³⁺ + Y ³⁺ + Gd ³⁺ + Yb ³⁺ )} is 1.75 or less, the above optical characteristics can be achieved. The lower limit and the preferred upper limit of the cation ratio {(B ³⁺ + Si ⁴⁺ ) / (La ³⁺ + Y ³⁺ + Gd ³⁺ + Yb ³⁺ )} are shown in Table 5 below.

In order to achieve the above optical characteristics while suppressing the decrease in the refractive index (nd) while improving the thermal stability of the glass, in the above glass, the total content of B ³⁺ and Si ⁴⁺ is relative to Nb ⁵⁺ , Ti ⁴⁺ The cation ratio {(B ³⁺ + Si ⁴⁺ ) / (Nb ⁵⁺ + Ti ⁴⁺ + Ta ⁵⁺ + W ⁶⁺ )} of the total content of Ta ⁵⁺ and W ⁶⁺ is 9.00 or less.

In order to improve the thermal stability of the glass while suppressing the decrease in the Abbe number (νd), it is preferred to make the cation ratio {(B ³⁺ + Si ⁴⁺ ) / (Nb ⁵⁺ + Ti ⁴⁺ + Ta ⁵⁺ + W) ⁶⁺ )} is 5.00 or more. Further, in order to further suppress the long wavelength of the light absorption end on the short-wavelength side of the glass, it is preferable to make the cation ratio {(B ³⁺ + Si ⁴⁺ ) / (Nb ⁵⁺ + Ti ⁴⁺ + Ta ⁵⁺ + W ⁶⁺ )} is 5.00 or more. As a result, when the glass lens is glued using the ultraviolet curable adhesive, the ultraviolet rays are more easily reached by the lens to the coating layer of the adhesive. Thereby, it becomes easier to cure the adhesive by ultraviolet irradiation.

A lower limit and a preferred upper limit of the cation ratio {(B ³⁺ + Si ⁴⁺ ) / (Nb ⁵ + + Ti ⁴ + + Ta ⁵ + + W ⁶⁺ )} are shown in Table 6 below.

In order to achieve the above optical characteristics while suppressing the crystallization of the glass while improving the thermal stability of the glass, the content of Zn ²⁺ in the above glass is relative to La ³⁺ , Y ³⁺ , Gd ³⁺ and Yb ^{3+ .} The cation ratio {Zn ²⁺ /(La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ³⁺ )} of the total content is set to be less than 0.2. The lower limit and the preferred upper limit of the cation ratio {Zn ²⁺ /(La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ³⁺ )} are shown in Table 7 below.

Among the rare earth elements lanthanum (La), yttrium (Y), yttrium (Gd), and yttrium (Yb), Gd is a heavy rare earth element, and from the viewpoint of stably supplying glass, it is required to reduce the content in the glass. ingredient. Further, Gd has a large atomic weight and is a component which increases the specific gravity of the glass.

Yb is also a heavy rare earth element and has a large atomic weight. In addition, Yb is near red The outer area is absorbed. On the other hand, in the interchangeable lens for a SLR camera and the lens of the surveillance video camera, it is desirable that the light transmittance in the near-infrared region is high. Therefore, in order to become a glass useful for producing these lenses, it is desirable to reduce the content of Yb.

On the other hand, La and Y do not adversely affect the light transmittance in the near-infrared region, and are appropriately distributed with respect to the total content of the rare earth elements, thereby suppressing an increase in specific gravity while improving thermal stability. It is a useful component for providing high refractive index low dispersion glass.

Therefore, in the above glass, on La ^3+, the content of La ³⁺ cations with respect to La ^3+, Y ^3+, Gd ³⁺ and the total content ratio of Yb ³⁺ {La ³⁺ / (La ³⁺ + The range of Y ³⁺ + Gd ³⁺ + Yb ³⁺ )} is set to 0.50 to 0.95. A preferred lower limit and a preferred upper limit of the cation ratio {La ³⁺ /(La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ³⁺ )} are shown in Table 8 below.

Further, regarding Y ^3+, the content of Y ³⁺ cations with respect to La ^3+, Y ^3+, Gd ³⁺ and the total content ratio of Yb ^{3+ {Y 3+ / (La 3+ +} Y 3+ + The range of Gd ³⁺ + Yb ³⁺ )} is set to 0.10 to 0.50. The lower limit and the preferred upper limit of the cation ratio {Y ³⁺ /(La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ³⁺ )} are shown in Table 9 below.

As described above, Gd ³⁺ is a component which should be reduced in glass from the viewpoint of stably supplying glass. In the above glass, the content of Gd ³⁺ is determined by the total content of La ³⁺ , Y ³⁺ , Gd ³⁺ and Yb ³⁺ and the content of Gd ³⁺ with respect to the total content. In the above glass, in order to stably supply the high refractive index low dispersion glass having the above optical characteristics, the content of Gd ³⁺ is relative to the total content of La ³⁺ , Y ³⁺ , Gd ^{3+ ,} and Yb ³⁺ . The ratio {Gd ³⁺ /(La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ³⁺ )} is set to 0.10 or less. Further, satisfying the above cation ratio can also contribute to the low specific gravity of the glass. The lower limit and the preferred upper limit of the cation ratio {Gd ³⁺ /(La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ³⁺ )} are shown in Table 10 below.

The total content of La ³⁺ , Y ³⁺ , Gd ³⁺ and Yb ³⁺ , and the content of La ³⁺ , the content of Y ³⁺ , and the content of Gd ³⁺ with respect to the cation ratio of the total content are as described above. Preferred lower limits and preferred upper limits of the contents of the respective components of La ³⁺ , Y ³⁺ , Gd ³⁺ and Yb ³⁺ are shown in Tables 11 to 14 below. Further, as for the content of Y ³⁺ , from the viewpoint of improving the thermal stability and the meltability of the glass, the lower limit shown in Table 12 below is also preferable.

Nb ⁵⁺ , Ti ⁴⁺ , Ta ^{5+ ,} and W ⁶⁺ are contained in an appropriate amount, and exhibit an effect of improving the refractive index and improving the thermal stability of the glass. However, when the content of Ti ⁴⁺ and W ⁶⁺ is increased, the absorption end on the short-wavelength side of the visible light region moves toward the long wavelength side. As a result, the light absorption end of the short-wavelength side of the glass is long-wavelength. Therefore, in the optical glass described above, in order to suppress the long-wavelength of the light-absorbing end of the short-wavelength side of the glass while improving the thermal stability of the glass, each of Nb ⁵⁺ , Ti ⁴⁺ , Ta ⁵⁺ , and W ⁶⁺ is considered. Based on the nature, determine the proportion of these contents. The details are as follows.

Nb ⁵⁺ has an effect of improving the refractive index (nd) and improving the thermal stability of the glass without increasing the specific gravity, coloring, and manufacturing cost of the glass. Further, Nb ⁵⁺ is a component which is less likely to cause a longer wavelength of the absorption end on the short-wavelength side of the glass than Ti ⁴⁺ and W ⁶⁺ . It is known that the absorption end of the short-wavelength side of glass can be represented by an index called λ5. That is to say, Nb ⁵⁺ is a component which is less likely to increase λ5 than Ti ⁴⁺ and W ⁶⁺ . Λ5 will be described in detail later.

On the other hand, when the content of Ti ⁴⁺ is increased, λ5 is increased. Further, there is a tendency that the transmittance in the visible light region of the glass is lowered and the color of the glass is increased.

Ta ⁵⁺ has a function of increasing the refractive index, and is a component which is less likely to cause a longer wavelength of the absorption end of the short-wavelength side of the glass than Nb ⁵⁺ , Ti ⁴⁺ , and W ⁶⁺ , but is an extremely expensive component. Therefore, from the viewpoint of stably supplying the glass, it is not preferable to use Ta ⁵⁺ actively. Further, when the content of Ta ^{5+ is} large, the raw material is liable to be melted and left when the glass is melted. In addition, the specific gravity of the glass will increase.

Regarding W ⁶⁺ , when its content increases, λ5 increases. In addition, the transmittance in the visible light region is lowered, and the specific gravity is increased.

As described above, Ta ⁵⁺ is a component which should be reduced in content. Therefore, Ta ⁵⁺ is not preferably used actively. In order to improve thermal stability and suppress long-wavelength (preferably reduce λ5) of the light-absorbing end on the short-wavelength side, in the above glass, the content of Nb ⁵⁺ is relative to that in Nb ⁵⁺ , Ti ⁴⁺ , Ta ⁵⁺ Nb ^5+, and W ⁶⁺ the addition of Ta ^5+, Ti ⁴⁺ cation and the total content ratio of W ^{6+ {Nb 5+ / (Nb 5+ +} Ti 4+ + W 6+)} to 0.80 or more. A preferred lower limit and a preferred upper limit of the cation ratio {Nb ⁵⁺ /(Nb ⁵⁺ + Ti ⁴⁺ + W ⁶⁺ )} are shown in Table 15 below.

Ta ^{5+ is} a content of Ta ⁵⁺ relative to Nb ⁵⁺ , Ti ⁴⁺ , Ta ⁵⁺ and W in order to improve the thermal stability of the glass while ^achieving high refractive index and low dispersion and reducing the amount of Ta used. the cation ratio of the total content of ^{6+ {Ta 5+ / (Nb 5+ +} Ti 4+ + Ta 5+ + W 6+)} is set to 0.2 or less. A preferred lower limit and a better upper limit of the cation ratio {Ta ⁵⁺ /(Nb ⁵⁺ + Ti ⁴⁺ + Ta ⁵⁺ + W ⁶⁺ )} are shown in Table 16 below.

Further, with respect to Nb ⁵⁺ , in order to stably supply the glass and reduce the content of Gd ³⁺ and Ta ⁵⁺ , it is desirable to lower the contents of Gd ³⁺ , Ta ⁵⁺ and Yb ³⁺ , and to provide suppression of the short-wavelength side. The long wavelength of the light absorption end (preferably λ5) and the high refractive index low dispersion glass excellent in thermal stability are based on the above effects of Nb ⁵⁺ , Ti ⁴⁺ , Ta ⁵⁺ , and W ⁶⁺ . , the preferred Nb ⁵⁺ cation content relative to Nb ^5+, Ti ^4+, Ta ^5+, and W ⁶⁺ total content ratio ^{{Nb 5+ / (Nb 5+ +} Ti 4+ + Ta 5+ + W ⁶⁺ )} is set to 0.4 or more. Further, in order to further suppress the long wavelength of the light absorption end on the short wavelength side, it is preferable to increase the cation ratio {Nb ⁵⁺ /(Nb ⁵⁺ + Ti ⁴⁺ + Ta ⁵⁺ + W ⁶⁺ )}. A lower limit and a preferred upper limit of the cation ratio {Nb ⁵⁺ /(Nb ⁵⁺ + Ti ⁴⁺ + Ta ⁵⁺ + W ⁶⁺ )} are shown in Table 17 below.

Further, in order to further suppress the long wavelength of the light absorption end on the short-wavelength side (preferably further suppressing the increase of λ5) and to promote the curing of the ultraviolet curable adhesive by ultraviolet irradiation, it is preferred to make the content of Ti ⁴⁺ relative to Nb ^{5 .} The cation ratio of the total content of ⁺ , Ti ⁴⁺ , Ta ⁵⁺ and W ⁶⁺ is {Ti ⁴⁺ /(Nb ⁵⁺ + Ti ⁴⁺ + Ta ⁵⁺ + W ⁶⁺ )} is 0.6 or less. A preferred lower limit and a better upper limit of the cation ratio {Ti ⁴⁺ /(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ )} are shown in Table 18 below.

Similarly, in order to further suppress the long wavelength of the light absorption end on the short wavelength side (preferably further suppressing the increase of λ5), it is preferred to make the content of W ⁶⁺ relative to Nb ⁵⁺ , Ti ⁴⁺ , Ta ⁵⁺ and W ^{6 . +} cation total content ratio ^{{W 6+ / (Nb 5+ +} Ti 4+ + Ta 5+ + W 6+)} is 0.2 or less. A preferred lower limit and a better upper limit of the cation ratio {W ⁶⁺ /(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ )} are shown in Table 19 below.

Among Nb ⁵⁺ , Ti ⁴⁺ , and W ⁶⁺ , Ti ⁴⁺ tends to increase the coloration of the glass, and the effect of increasing λ5 is also strong. In order to suppress an increase λ5, preferably the content of Ti ⁴⁺ cation with respect to the total content of Nb ^5+, Ti ⁴⁺ and W ⁶⁺ and ^{(Nb 5+ + Ti 4+ + W} 6+) ratio of Ti ⁴⁺ { The upper limit of /(Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ )} is a value of the preferred upper limit shown in Table 20 below. Further, the cation ratio {Ti ⁴⁺ /(Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ )} can also be made zero.

In order to suppress the decrease in the Abbe number (νd) while maintaining the thermal stability of the glass, it is preferable to make the total content of La ³⁺ , Y ³⁺ , Gd ³⁺ and Yb ³⁺ (La ³⁺ + Y ³⁺ + Cd ratio of Gd ³⁺ +Yb ³⁺ ) relative to the total content of Nb ⁵⁺ , Ti ⁴⁺ , Ta ⁵⁺ and W ⁶⁺ (Nb ⁵⁺ + Ti ⁴⁺ + Ta ⁵⁺ + W ⁶⁺ ) {( The lower limit of La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ³⁺ )/(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ )} is the preferred lower limit value shown in Table 21 below. .

On the other hand, in order to maintain the thermal stability of the glass while suppressing the decrease in the refractive index, it is preferred to make the cation ratio {(La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ³⁺ )/(Nb ⁵⁺ +Ti) The upper limit of ⁴⁺ + Ta ⁵⁺ + W ⁶⁺ )} is the value of the preferred upper limit shown in Table 21 below.

The glass composition of the glass A will be further described below.

The total content of B ³⁺ and Si ⁴⁺ as the network forming component of the glass is as described above. Regarding B ³⁺ and Si ⁴⁺ , although B ³⁺ is superior to Si ^{4+ in} improving the meltability, it is volatilized at the time of melting. On the other hand, Si ⁴⁺ has an effect of improving chemical durability, weather resistance, machinability, and viscosity of glass at the time of melting.

In general, in a high refractive index low dispersion glass containing a rare earth element such as B ³⁺ and La ³⁺ , the viscosity of the glass at the time of melting is low. However, when the viscosity of the glass at the time of melting is low, it becomes easy to crystallize. The crystallization during the production of glass is caused by the fact that the crystallization is more stable than the amorphous state (amorphous state), and the ions constituting the glass move in the glass to be arranged to have a crystal structure. Therefore, by adjusting the ratio of the content of each component of B ³⁺ and Si ⁴⁺ to improve the viscosity at the time of melting, the ions can be hardly arranged to have a crystal structure, and the crystallization of the glass can be further suppressed to further improve the glass. Resistance to devitrification.

From the above viewpoint, the content of B ³⁺ and B ³⁺ cations with respect to the total content of Si ⁴⁺ preferred lower limit of the ratio of ^{{B 3+ / (B 3+ +} Si 4+)} and preferred The upper limit is shown in Table 22 below. From the viewpoint of improving the meltability of the glass, it is also preferable to set the lower limit or more as shown in Table 22 below. Further, in order to increase the viscosity of the glass during melting, it is preferably set to be equal to or lower than the upper limit shown in Table 22 below. Furthermore, in order to reduce fluctuations in the glass composition and fluctuations in optical characteristics due to volatilization during melting, it is also preferable from the viewpoint of improving one or more of chemical durability, weather resistance, and machinability of the glass. Set to the upper limit shown in Table 22 below.

From the viewpoints of improving the devitrification resistance, the meltability, the moldability, the chemical durability, the weather resistance, the machinability, and the like of the glass, the contents of B ^{3+ and} the content of Si ⁴⁺ are shown in Tables 23 to 24, respectively. A preferred lower limit and a preferred upper limit.

Zn ²⁺ has an effect of promoting melting of the glass raw material when the glass is melted, that is, has an effect of improving meltability. Further, it has an effect of adjusting the refractive index (nd), the Abbe number (νd), and lowering the glass transition temperature. From the viewpoint of suppressing the decrease in the Abbe number (νd), improving the thermal stability of the glass, and suppressing the decrease in the glass transition temperature (thus improving the machinability), the content of Zn ²⁺ is divided by B ³⁺ and Si. The value of the total content of ⁴⁺ , that is, the cation ratio {Zn ²⁺ /(B ³⁺ +Si ⁴⁺ )} is preferably set to 0.15 or less. Further, in the above glass, Zn may or may not contain optional components. Therefore, the cation ratio {Zn ²⁺ /(B ³⁺ +Si ⁴⁺ )} is preferably 0 or more, but in order to improve the meltability, It is easy to produce a homogeneous glass, more preferably containing zinc (Zn) and setting the cation ratio {Zn ²⁺ /(B ³⁺ +Si ⁴⁺ )} to more than zero. A lower limit and a better upper limit of the cation ratio {Zn ²⁺ /(B ³⁺ +Si ⁴⁺ )} are shown in Table 25 below.

In order to improve the meltability, thermal stability, moldability, machinability, and the like of the glass and to realize the above optical characteristics, a preferred lower limit and a preferred upper limit of the content of Zn ²⁺ are shown in Table 26 below.

The content of Zn ²⁺ is relative to Nb ⁵⁺ , Ti ⁴⁺ , Ta ⁵ from the viewpoint of further improving the thermal stability of the glass, suppressing the decrease in the glass transition temperature (thereby improving the machinability), and improving the chemical durability. The cation ratio {Zn ²⁺ /(Ti ⁴⁺ + Nb ⁵⁺ + Ta ⁵⁺ + W ⁶⁺ )} of the total content of ⁺ and W ⁶⁺ is preferably 1.0 or less. On the other hand, Zn is an optional component, so the lower limit of the cation ratio {Zn ²⁺ /(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ )} is preferably 0, but from the improvement of the meltability, further From the viewpoint of suppressing the long wavelength of the light absorption end on the short wavelength side (preferably, further suppressing the increase of λ5), it is more preferable to exceed zero. When considering the above aspects, a lower limit and a higher upper limit of the cation ratio {Zn ²⁺ /(Ti ⁴⁺ + Nb ⁵⁺ + Ta ⁵⁺ + W ⁶⁺ )} are shown in Table 27 below.

About ^{Nb 5+, Ti 4+, Ta 5+} , W 6+, in consideration of the above effect based on the effect, the Nb ^5+, Ti ^{4+, 5+} content of Ta, and W ⁶⁺ is a component The preferred ranges are shown in Tables 28 to 31 below.

Next, optional components other than the components described above will be described.

Since Li ⁺ has a strong effect of lowering the glass transition temperature, when the content thereof is increased, the tendency of the machinability is lowered. Further, chemical durability and weather resistance also tend to decrease. Therefore, the content of Li ⁺ is preferably made 5% or less. A preferred lower limit and a better upper limit of the content of Li ⁺ are shown in Table 32 below. The content of Li ⁺ can also be set to 0%.

Na ⁺ , K ⁺ , Rb ⁺ , and Cs ⁺ all have an effect of improving the meltability of the glass. However, when the content thereof is increased, the thermal stability, chemical durability, weather resistance, and machinability of the glass are lowered. tendency. Therefore, the lower limit and the upper limit of the respective contents of Na ⁺ , K ⁺ , Rb ⁺ and Cs ⁺ are preferably set as shown in the following Tables 33 to 36, respectively.

In order to improve the glass meltability while maintaining the thermal stability, chemical durability, weather resistance and machinability of the glass, the total content of Li ⁺ , Na ⁺ and K ⁺ (Li ⁺ + Na ⁺ + K ⁺ ) The lower limit and the preferred upper limit are shown in Table 37 below.

Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , and Ba ²⁺ are all components having an effect of improving the meltability of the glass. However, when the content of these components is increased, the thermal stability of the glass is lowered, showing a tendency to devitrification. Therefore, the content of each of these components is preferably set to be equal to or higher than the lower limit and lower limit shown in the following Tables 38 to 41, respectively.

Further, in order to maintain the thermal stability of the glass, the total content of Mg ²⁺ , Ca ²⁺ , Sr ^{2+ ,} and Ba ²⁺ (Mg ²⁺ + Ca ²⁺ + Sr ²⁺ + Ba ²⁺ ) is preferably set to The lower limit or more and the upper limit shown in

Al ³⁺ is a component having an effect of improving the chemical durability and weather resistance of the glass. However, when the content of Al ³⁺ is increased, the refractive index (nd) tends to decrease, the thermal stability of the glass tends to decrease, and the meltability tends to decrease. In view of the above, the content of Al ³⁺ is preferably set to be equal to or higher than the lower limit and lower than the upper limit shown in Table 43 below.

Ga ³⁺ , In ³⁺ , Sc ³⁺ , and Hf ⁴⁺ all have an effect of increasing the refractive index (nd). However, these components are expensive and are not essential components for obtaining the above optical glass. Therefore, the content of each of Ga ³⁺ , In ³⁺ , Sc ³⁺ , and Hf ⁴⁺ is preferably set to be equal to or higher than the lower limit and lower than the upper limit shown in Tables 44 to 47 below.

Lu ³⁺ has an effect of increasing the refractive index (nd), but it is also a component that increases the specific gravity of the glass. Further, since Lu (Lu) is a heavy rare earth element similarly to Gd and Yb, it is preferable to reduce the content of Lu. From the above aspects, a preferred lower limit and a preferred upper limit of the content of Lu ³⁺ are shown in Table 48 below.

Ge ⁴⁺ has an effect of increasing the refractive index (nd), but it is a particularly expensive component among the commonly used glass components. In order to reduce the manufacturing cost of the glass, a preferred lower limit and a preferred upper limit of the content of Ge ⁴⁺ are shown in Table 49 below.

Bi ³⁺ is a component that increases the refractive index (nd) and lowers the Abbe number (νd). In addition, it is a component that easily increases the color of the glass. In order to produce a glass having the above optical characteristics and having little coloration, a preferred lower limit and a preferred upper limit of the content of Bi ³⁺ are shown in Table 50 below.

In order to satisfactorily obtain the various actions and effects described above, the total content (total content) of each of the cationic components described above is preferably more than 95%, more preferably more than 98%, still more preferably more than 99%, still more preferably more than 99.5%.

In the cationic component other than the cationic component described above, P ⁵⁺ is a component that lowers the refractive index (nd) or a component that lowers the thermal stability of the glass. However, introduction of a small amount may thermally stabilize the glass. Sexual improvement. In order to produce a glass having the above optical characteristics and excellent thermal stability, a preferred lower limit and a preferred upper limit of the content of P ⁵⁺ are shown in Table 51 below.

Te ⁴⁺ is a component that increases the refractive index (nd), but since it is a toxic component, it is preferable to reduce the content of Te ⁴⁺ . A preferred lower limit and a preferred upper limit of the content of Te ⁴⁺ are shown in Table 52 below.

Further, in each of the above tables, a component of 0% is described in a (better) lower limit or upper limit, and the content thereof is preferably 0%. The same is true for the total content of various components.

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

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

Vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), mal (Pr), niobium (Nd), niobium (Pm), Sm, Eu, Tb, Dy, Ho, Er, Tm The source of light is not preferable as an element contained in the glass for an optical element. Therefore, it is preferred not to contain these elements, that is, it is preferable not to introduce these elements into the glass as a glass component.

Sb (Sb) and tin (Sn) are elements which can be optionally added as a clarifying agent.

In terms of antimony trioxide (Sb ₂ O ₃₎ is set and the total content of the glass component other than Sb ₂ O ₃ 100 mass%, Sb in the range of the addition amount is preferably from 0 to 0.11% by mass, and more It is preferably 0.01 to 0.08 mass%, more preferably 0.02 to 0.05 mass%.

When terms of tin oxide (SnO ₂₎ and the content of the glass component other than ₂ SnO total of 100% by mass, the range of Sn is preferably added in an amount of 0 to 0.5% by mass, more preferably from 0 to 0.2% by mass, further preferably 0% by mass.

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

The glass is an oxide glass, so as an anionic component comprising O ^2-. The content of O ^2- is preferably in the range of 98 to 100 anionic %, more preferably 99 to 100 anionic %, still more preferably 100 anionic %.

Examples of the anion component other than O ²⁻ are F ⁻ , Cl ⁻ , Br ⁻ , and I ⁻ . Here, F ^- , Cl ^- , Br ^- , and I ^- are all easily volatilized in the melting of the glass. Due to the volatilization of these components, there is a tendency that the characteristics of the glass fluctuate, the homogeneity of the glass is lowered, or the consumption of the melting equipment becomes remarkable. Therefore, it is preferred to suppress the total content of F ^- , Cl ^- , Br ^- and I ^{- to} an amount obtained by subtracting the content of O ^2- from 100 anions %.

Further, it is known that the percentage of anion is a percentage of the total content of all the anionic components contained in the glass to 100%.

[Glass B]

Next, the glass B will be described.

The glass B according to an embodiment of the present invention is an oxide glass having the above glass composition, the Abbe number (νd) is in the range of 39.5 to 41.5, and the refractive index (nd) and the Abbe number (νd) satisfy the above formula. (1). The glass B will be described in detail below.

In the present invention, the glass composition of the glass B is represented by an oxide. Here, the "glass composition based on an oxide" means a glass composition obtained by converting a glass raw material into a glass by being completely decomposed at the time of melting and being present as an oxide in the glass. In addition, unless otherwise indicated, the glass composition of the glass B is represented by mass (mass %, mass ratio).

<glass composition>

Boron trioxide (B ₂ O ₃ ) and cerium oxide (SiO ₂ ) are network forming components of glass. When the total content of B ₂ O ₃ and SiO ₂ (B ₂ O ₃ + SiO ₂ ) is 17.5% or more, the thermal stability of the glass is improved, and crystallization of the glass in the production process can be suppressed. On the other hand, when the total content of B ₂ O ₃ and SiO ₂ is 35% or less, the decrease in the refractive index (nd) can be suppressed, and thus the glass having the above optical characteristics can be produced. Therefore, the range of the total content of B ₂ O ₃ and SiO ₂ in the above glass is set to be 17.5 to 35%. A preferred lower limit and a preferred upper limit of the total content of B ₂ O ₃ and SiO ₂ are shown in Table 53 below.

Antimony trioxide (La ₂ O ₃ ), antimony trioxide (Y ₂ O ₃ ), antimony trioxide (Gd ₂ O ₃ ) and antimony trioxide (Yb ₂ O ₃ ) have an Abbe number in suppression A component that reduces the effect of the refractive index while reducing (νd). In addition, these ingredients also have an effect of improving the chemical durability, weather resistance, and glass transition temperature of the glass.

When the total content of La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O _{3 ,} and Yb ₂ O ₃ (La ₂ O ₃ + Y ₂ O ₃ + Gd ₂ O ₃ + Yb ₂ O ₃ ) is 45% or more, Since the decrease in the refractive index (nd) can be suppressed, it is possible to produce a glass having the above optical characteristics. Further, it is also possible to suppress chemical durability and deterioration of weather resistance of the glass. Further, when the glass transition temperature is lowered, the glass is easily broken (machineability is lowered) when the glass is machined (cut, cut, polished, polished, etc.), when La ₂ O ₃ , Y ₂ O ₃ , Gd _When the total content of ₂ O ₃ and Yb ₂ O ₃ is 45% or more, the decrease in the glass transition temperature can be suppressed, so that the machinability can be improved. On the other hand, when the total content of each component of La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O _{3 ,} and Yb ₂ O ₃ is 70% or less, the thermal stability of the glass can be improved, and thus the production can be suppressed. Crystallization in the case of glass reduces the melting of the raw material when the glass is melted. In addition, it is also possible to suppress an increase in the specific gravity. Therefore, in the above glass, the total content of La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ and Yb ₂ O _{3 is} in the range of 45 to 70%. The lower limit and the preferred upper limit of the total content of La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ and Yb ₂ O ₃ are shown in Table 54 below.

Bismuth pentoxide (Nb ₂ O ₅ ), titanium dioxide (TiO ₂ ), tantalum pentoxide (Ta ₂ O ₅ ), and tungsten oxide (WO ₃ ) are components having an effect of increasing the refractive index, and are contained in an appropriate amount. It also has the effect of improving the thermal stability of the glass. When the total content of Nb ₂ O ₅ , TiO ₂ , Ta ₂ O ₅ and WO ₃ (Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ + WO ₃ ) is 3% or more, it is possible to maintain thermal stability while maintaining thermal stability. The above optical characteristics are achieved. On the other hand, when the total content of Nb ₂ O ₅ , TiO ₂ , Ta ₂ O ₅ and WO ₃ is 16% or less, it is possible to suppress a decrease in thermal stability and a decrease in Abbe number (νd). Further, it is also possible to suppress an increase in the coloring degree (λ5) to be described later and to increase the ultraviolet transmittance of the glass. Therefore, in the above glass, the total content of Nb ₂ O ₅ , TiO ₂ , Ta ₂ O ₅ and WO _{3 is} in the range of 3 to 16%. The lower limit and the preferred upper limit of the total content of Nb ₂ O ₅ , TiO ₂ , Ta ₂ O ₅ and WO ₃ are shown in Table 55 below.

Zirconium dioxide (ZrO ₂ ) is a component having an effect of increasing the refractive index, and has an effect of improving the thermal stability of the glass by being contained in an appropriate amount. Further, ZrO ₂ also has an effect of making the glass less susceptible to breakage during machining by increasing the glass transition temperature. In order to obtain these effects favorably, the content of ZrO ₂ in the above glass is 2% or more. On the other hand, when the content of ZrO ₂ is 10% or less, the thermal stability of the glass can be improved. Therefore, it is possible to suppress crystallization during the production of glass and to cause melt residue during glass melting. Therefore, the range of the content of ZrO ₂ in the above glass is set to 2 to 10%. A preferred lower limit and a preferred upper limit of the content of ZrO ₂ are shown in Table 56 below.

In order to improve the thermal stability of the glass, the Abbe number (νd) is 39.5 to 41.5 and the refractive index (nd) and the Abbe number (νd) satisfy the optical characteristics of the above formula (1), in the above glass. a mass ratio of the total content of boron trioxide (B ₂ O ₃ ) and cerium oxide (SiO ₂ ) to the total content of 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 + Y ₂ O ₃ + Gd ₂ O ₃ + Yb ₂ O ₃ )} is set to 0.2 to 0.5. If the mass ratio {(B ₂ O ₃ + SiO ₂ ) / (La ₂ O ₃ + Y ₂ O ₃ + Gd ₂ O ₃ + Yb ₂ O ₃ )} is 0.2 or more, the thermal stability of the glass can be improved, so It can suppress the devitrification of the glass. In addition, it is also possible to suppress an increase in the specific gravity of the glass. When the specific gravity of the glass is increased, the optical element made using the glass becomes heavy. As a result, the optical system in which the optical element is assembled becomes heavy. For example, when a heavy optical component is assembled into an autofocus camera, the power consumption when driving autofocus increases, and the battery is quickly consumed. From the viewpoint of reducing the weight of the optical element produced using the glass and the optical system in which the optical element is assembled, it is preferable to suppress an increase in the specific gravity of the glass. On the other hand, if the mass ratio {(B ₂ O ₃ + SiO ₂ ) / (La ₂ O ₃ + Y ₂ O ₃ + Gd ₂ O ₃ + Yb ₂ O ₃ )} is 0.5 or less, the above optical can be realized. characteristic. The lower limit and the preferred upper limit of the mass ratio {(B ₂ O ₃ + SiO ₂ ) / (La ₂ O ₃ + Y ₂ O ₃ + Gd ₂ O ₃ + Yb ₂ O ₃ )} are shown in Table 57 below. .

In order to suppress the decrease in the refractive index (nd) and to achieve the above optical characteristics while improving the thermal stability of the glass, the total content of B ₂ O ₃ and SiO ₂ in the above glass is relative to Nb ₂ O ₅ , TiO _{2 .} The mass ratio {(B ₂ O ₃ + SiO ₂ ) / (Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ + WO ₃ )} of the total content of Ta ₂ O ₅ and WO ₃ was 2.8 or less.

In order to improve the thermal stability of the glass while suppressing the decrease in the Abbe number (νd), it is preferred to make the mass ratio {(B ₂ O ₃ + SiO ₂ ) / (Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ + WO ₃ )} is 1.2 or more. Further, in order to further suppress the long wavelength of the light absorption end on the short-wavelength side of the glass, it is preferable to make the mass ratio {(B ₂ O ₃ + SiO ₂ ) / (Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ + WO ₃ )} is 1.2 or more. As a result, when the glass lens is glued using the ultraviolet curable adhesive, the ultraviolet rays are more easily reached by the lens to the coating layer of the adhesive. Thereby, it becomes easier to cure the adhesive by ultraviolet irradiation.

A lower limit and a preferred upper limit of the mass ratio {(B ₂ O ₃ + SiO ₂ ) / (Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ + WO ₃ )} are shown in Table 58 below.

In order to improve the thermal stability of the glass and achieve the above optical characteristics, the content of zinc oxide (ZnO) in the above glass is relative to the total content of La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ and Yb ₂ O ₃ . The mass ratio {ZnO/(La ₂ O ₃ +Y ₂ O ₃ +Gd ₂ O ₃ +Yb ₂ O ₃ )} was set to be less than 0.10. The lower limit and the preferred upper limit of the mass ratio {ZnO/(La ₂ O ₃ + Y ₂ O ₃ + Gd ₂ O ₃ + Yb ₂ O ₃ )} are shown in Table 59 below.

Among the rare earth elements La, Y, Gd, and Yb, Gd is a heavy rare earth element, and is a component that is required to lower the content in the glass from the viewpoint of stably supplying the glass. Further, Gd has a large atomic weight and is a component which increases the specific gravity of the glass.

Yb is also a heavy rare earth element and has a large atomic weight. In addition, Yb absorbs the near-infrared region. On the other hand, in the interchangeable lens for a SLR camera and the lens of the surveillance video camera, it is desirable that the light transmittance in the near-infrared region is high. because Therefore, in order to become a glass useful for producing these lenses, it is desirable to reduce the content of Yb.

On the other hand, La and Y do not adversely affect the light transmittance in the near-infrared region, and are appropriately distributed with respect to the total content of the rare earth elements, thereby suppressing an increase in specific gravity while improving thermal stability. It is a useful component for providing high refractive index low dispersion glass.

Therefore, in the glass, on La, the content of La ₂ O ₃ with respect to _{La 2 O 3, Y 2 O} 3, the quality of the total content of Gd ₂ O ₃ and Yb ₂ O ₃ ratio {La ₂ O ₃ / The range of (La ₂ O ₃ +Y ₂ O ₃ +Gd ₂ O ₃ +Yb ₂ O ₃ )} is set to 0.55 to 0.98. The lower limit and the preferred upper limit of the mass ratio {La ₂ O ₃ /(La ₂ O ₃ +Y ₂ O ₃ +Gd ₂ O ₃ +Yb ₂ O ₃ )} are shown in Table 60 below.

Further, with respect to Y, the content of Y ₂ O ₃ with respect to _{La 2 O 3, Y 2 O} 3, Gd mass total content ₂ O ₃ and Yb ₂ O ₃ ratio of _{{Y 2 O 3 / (La} 2 O 3 The range of +Y ₂ O ₃ +Gd ₂ O ₃ +Yb ₂ O ₃ )} is set to 0.02 to 0.45. A preferred lower limit and a preferred upper limit of the mass ratio {Y ₂ O ₃ /(La ₂ O ₃ +Y ₂ O ₃ +Gd ₂ O ₃ +Yb ₂ O ₃ )} are shown in Table 61 below.

As described above, Gd is a component which should lower the content in the glass from the viewpoint of stably supplying the glass. In the above glass, the content of Gd is determined by the total content of La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ , Yb ₂ O ₃ and the content of Gd ₂ O ₃ relative to the total content. In the above glass, in order to stably supply the high refractive index low dispersion glass having the above optical characteristics, the content of Gd ₂ O ₃ is relative to La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ and Yb ₂ O _{3 .} total content mass ratio of _{{Gd 2 O 3 / (La} 2 O 3 + Y 2 O 3 + Gd 2 O 3 + Yb 2 O 3)} is 0.10 or less. Further, satisfying the above mass ratio can also contribute to the low specific gravity of the glass. The lower limit and the preferred upper limit of the mass ratio {Gd ₂ O ₃ /(La ₂ O ₃ +Y ₂ O ₃ +Gd ₂ O ₃ +Yb ₂ O ₃ )} are shown in Table 62 below.

The total content of La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ and Yb ₂ O ₃ , and the content of La ₂ O ₃ , the content of Y ₂ O ₃ , and the content of Gd ₂ O ₃ with respect to the total content For example, as described above. The lower limit and the preferred upper limit of the content of each component of La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ , and Yb ₂ O ₃ are shown in Tables 63 to 66 below. Further, as for the content of Y ₂ O ₃ , from the viewpoint of improving the thermal stability and the meltability of the glass, the lower limit shown in Table 64 below is also preferable.

Nb, Ti, Ta, and W are contained in an appropriate amount, and exhibit an effect of improving the refractive index and improving the thermal stability of the glass. However, when the content of titanium (Ti) or tungsten (W) is increased, the absorption end on the short-wavelength side of the visible light region moves toward the long wavelength side. As a result, the light absorption end of the short-wavelength side of the glass is long-wavelength. Therefore, in the optical glass described above, in order to suppress the long-wavelength of the light-absorbing end of the short-wavelength side of the glass while improving the thermal stability of the glass, the basis of the properties of niobium (Nb), Ti, Ta, and W is considered. Above, determine the ratio of these contents. The details are as follows.

Nb has an effect of improving the refractive index (nd) and improving the thermal stability of the glass without increasing the specific gravity, coloring, and manufacturing cost of the glass. Further, Nb is a component which is less likely to cause a longer wavelength of the absorption end on the short-wavelength side of the glass than Ti and W. It is known that the absorption end of the short-wavelength side of the glass can be represented by an index called λ5. That is to say, Nb is a component which is less likely to increase λ5 than Ti and W. Λ5 will be described in detail later.

On the other hand, when the content of Ti increases, λ5 increases. Further, there is a tendency that the transmittance in the visible light region of the glass is lowered and the color of the glass is increased.

Ta has a function of increasing the refractive index, and further has a component which is less likely to cause a longer wavelength of the absorption end of the glass on the shorter wavelength side than Nb, Ti, and W, but is an extremely expensive component. Therefore, from the viewpoint of stably supplying the glass, it is not preferable to use Ta ⁵⁺ actively. Further, when the content of Ta is large, the raw material is likely to be melted and left when the glass is melted. In addition, the specific gravity of the glass will increase.

Regarding W, when its content increases, λ5 increases. In addition, the transmittance in the visible light region is lowered, and the specific gravity is increased.

As described above, Ta is a component which should be reduced in content. Therefore, Ta is not preferably used actively. In order to improve thermal stability and suppress long-wavelength (preferably reduce λ5) of the light-absorbing end on the short-wavelength side, in the above glass, the content of Nb ₂ O ₅ is relative to that in Nb ₂ O ₅ , TiO ₂ , Ta ₂ O _5, WO ₃ in addition to the Ta ₂ O ₅ Nb ₂ O _5, the total content by mass of TiO _2, and WO ₃ ratio _{{Nb 2 O 5 / (Nb} 2 O 5 + TiO 2 + WO 3)} provided It is 0.81 or more. A preferred lower limit and a preferred upper limit of the mass ratio {Nb ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ )} are shown in Table 67 below.

Regarding Ta, while in order to improve the thermal stability of the glass a high refractive index and low dispersion of the seek, reduce the amount of Ta, the content of Ta ₂ O ₅ with respect to the _{Nb 2 O 5, TiO 2,} Ta 2 O 5 and WO _3, the total content mass ratio of _{{Ta 2 O 5 / (Nb} 2 O 5 + TiO 2 + Ta 2 O 5 + WO 3)} is set to 0.3 or less. A preferred lower limit and a better upper limit of the mass ratio {Ta ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +Ta ₂ O ₅ +WO ₃ )} are shown in Table 68 below.

Further, regarding Nb, in order to stably supply the glass, to lower the content of Gd and Ta, it is desirable to lower the contents of Gd, Ta, and Yb, and to provide long-wavelength reduction (preferably to reduce λ5) of the light-absorbing end on the short-wavelength side. ), good thermal stability, high-refractivity low-dispersion glass, in consideration of the basis of the above effects Nb, Ti, Ta, W, based on the preferred content of Nb ₂ O ₅ with respect to the Nb ₂ O _5, TiO _2, The mass ratio {Nb ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +Ta ₂ O ₅ +WO ₃ )} of the total content of Ta ₂ O ₅ and WO ₃ is set to 0.5 or more. Further, in order to further suppress the long wavelength of the light absorption end on the short wavelength side, it is preferable to increase the mass ratio {Nb ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +Ta ₂ O ₅ +WO ₃ )}. A lower limit and a preferred upper limit of the mass ratio {Nb ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +Ta ₂ O ₅ +WO ₃ )} are shown in Table 69 below.

Further, in order to further suppress the long wavelength of the light absorption end on the short-wavelength side (preferably further suppressing the increase of λ5) and to promote the curing of the ultraviolet curable adhesive by ultraviolet irradiation, it is preferred to make the content of TiO ₂ relative to Nb ₂ O. _5, TiO _2, mass of the total content of Ta ₂ O ₅ and WO ₃ ratio _{{TiO 2 / (Nb 2 O} 5 + TiO 2 + Ta 2 O 5 + WO 3)} is 0.40 or less. A preferred lower limit and a higher upper limit of the mass ratio {TiO ₂ /(Nb ₂ O ₅ +TiO ₂ +Ta ₂ O ₅ +WO ₃ )} are shown in Table 70 below.

Likewise, in order to further suppress the short wavelength side of the light absorption of the longer wavelength side (preferably to further suppress the increase in λ5), preferably the content of WO ₃ with respect to the _{Nb 2 O 5, TiO 2,} Ta 2 O 5 and WO ₃ The mass ratio of the total content of {WO ₃ /(Nb ₂ O ₅ +TiO ₂ +Ta ₂ O ₅ +WO ₃ )} is 0.3 or less. A preferred lower limit and a better upper limit of the mass ratio {WO ₃ /(Nb ₂ O ₅ +TiO ₂ +Ta ₂ O ₅ +WO ₃ )} are shown in Table 71 below.

Among Nb, Ti, and W, Ti tends to increase the color of the glass, and the effect of increasing λ5 is also strong. In order to suppress the increase in λ5, preferred that the content of TiO ₂ with respect to the Nb ₂ O _5, the total content mass _{(Nb 2 O 5 + TiO 2} + WO 3) of TiO ₂ and WO ₃ ratio {TiO ₂ / (Nb ₂ The upper limit of O ₅ +TiO ₂ +WO ₃ )} is a value of the preferred upper limit shown in Table 72 below. Further, the mass ratio {TiO ₂ /(Nb ₂ O ₅ +TiO ₂ +WO ₃ )} can also be made zero.

In order to suppress the decrease in the Abbe number (νd) while maintaining the thermal stability of the glass, it is preferred to make the total content of La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ and Yb ₂ O ₃ (La ₂ O _{3 )} +Y ₂ O ₃ +Gd ₂ O ₃ +Yb ₂ O ₃ ) with respect to the total content of Nb ₂ O ₅ , TiO ₂ , Ta ₂ O ₅ and WO ₃ (Nb ₂ O ₅ +TiO ₂ +Ta ₂ O ₅ + WO ₃₎ the mass ratio of _{{(La 2 O 3 + Y} 2 O 3 + Gd 2 O 3 + Yb 2 O 3) / (Nb 2 O 5 + TiO 2 + Ta 2 O 5 + WO 3)} is a lower limit of The values of the preferred lower limits shown in Table 73 below.

On the other hand, in order to maintain the thermal stability of the glass while suppressing the decrease in the refractive index, it is preferred to make the mass ratio {(La ₂ O ₃ +Y ₂ O ₃ +Gd ₂ O ₃ +Yb ₂ O ₃ )/(Nb) The upper limit of ₂ O ₅ +TiO ₂ +Ta ₂ O ₅ +WO ₃ )} is a value of the preferred upper limit shown in Table 73 below.

The glass composition of the above glass will be further described below.

The total content of B ₂ O ₃ and SiO ₂ as a network forming component of glass is as described above. Regarding B ₂ O ₃ and SiO ₂ , B ₂ O ₃ is superior to SiO _{2 in} improving the meltability, but is volatilized at the time of melting. On the other hand, SiO ₂ has an effect of improving chemical durability, weather resistance, machinability, and viscosity of glass at the time of melting.

Generally, in a high refractive index low dispersion glass containing a rare earth element such as boron (B) or La, the viscosity of the glass at the time of melting is low. However, when the viscosity of the glass at the time of melting is low, it becomes easy to crystallize. The crystallization during the production of glass is caused by the fact that the crystallization is more stable than the amorphous state (amorphous state), and the ions constituting the glass move in the glass to be arranged to have a crystal structure. Therefore, by adjusting the ratio of the content of each component of B ₂ O ₃ and SiO ₂ , the viscosity at the time of melting is improved, so that the ions are hardly arranged to have a crystal structure, and crystallization of the glass can be further suppressed, and the glass can be further improved. Resistance to devitrification.

From the above viewpoint, the content of B ₂ O ₃ with respect to the lower and more preferred mass B ₂ O ₃ and SiO ₂ ratio of the total content of _{{B 2 O 3 / (B} 2 O 3 + SiO 2)} of The upper limit is shown in Table 74 below. From the viewpoint of improving the meltability of the glass, it is preferably set to be equal to or higher than the lower limit shown in the following Table 74. Further, in order to increase the viscosity of the glass during melting, it is preferably set to be equal to or less than the upper limit shown in the following Table 74. Furthermore, in order to reduce fluctuations in the glass composition and fluctuations in optical characteristics due to volatilization during melting, it is also preferable from the viewpoint of improving one or more of chemical durability, weather resistance, and machinability of the glass. Set to the upper limit shown in Table 74 below.

From the viewpoints of improving the devitrification resistance, meltability, moldability, chemical durability, weather resistance, and machinability of the glass, the contents of B ₂ O ₃ and SiO ₂ are shown in Tables 75 to 76 below. A preferred lower limit and a preferred upper limit.

ZnO has an effect of promoting melting of the glass raw material when the glass is melted, that is, has an effect of improving meltability. Further, it has an effect of adjusting the refractive index (nd), the Abbe number (νd), and lowering the glass transition temperature. From the viewpoint of suppressing the decrease in the Abbe number (νd), improving the thermal stability of the glass, and suppressing the decrease in the glass transition temperature (thus improving the machinability), the content of ZnO is divided by B ₂ O ₃ and SiO _{2 .} The value of the total content, that is, the mass ratio {ZnO/(B ₂ O ₃ + SiO ₂ )} is preferably set to 0.30 or less. Further, since ZnO is an optional component which may or may not be contained in the glass, the mass ratio {ZnO/(B ₂ O ₃ + SiO ₂ )} is preferably 0 or more, but is easily produced in order to improve the meltability. The homogeneous glass preferably contains Zn and has a mass ratio of {ZnO/(B ₂ O ₃ + SiO ₂ )} exceeding 0. A lower limit and a better upper limit of the mass ratio {ZnO/(B ₂ O ₃ + SiO ₂ )} are shown in Table 77 below.

In order to improve the meltability, thermal stability, moldability, machinability, and the like of the glass and to realize the above optical characteristics, a preferred lower limit and a preferred upper limit of the content of ZnO are shown in Table 78 below.

From the viewpoint of further improving the thermal stability of the glass, suppressing the decrease in the glass transition temperature (thereby improving the machinability), and improving the chemical durability, the content of ZnO is preferably relative to Nb ₂ O ₅ , TiO ₂ , Ta _{2 .} The mass ratio {ZnO/(Nb ₂ O ₅ +TiO ₂ +Ta ₂ O ₅ +WO ₃ )} of the total content of O ₅ and WO ₃ is less than 0.61. On the other hand, since Zn is an optional component, the lower limit of the mass ratio {ZnO/(Nb ₂ O ₅ +TiO ₂ +Ta ₂ O ₅ +WO ₃ )} is preferably 0, but the melting property is further improved and the suppression is further suppressed. From the viewpoint of increasing the wavelength of the light absorption end on the wavelength side (preferably further suppressing the increase of λ5), it is more preferable to exceed zero. When the above considerations, the mass ratio _{{ZnO / (Nb 2 O 5} + TiO 2 + Ta 2 O 5 + WO 3)} a better and better upper limit as shown in Table 79.

Regarding Nb ₂ O ₅ , TiO ₂ , Ta ₂ O ₅ , and WO ₃ , in consideration of the above actions and effects, Nb ₂ O ₅ , TiO ₂ , Ta ₂ O ₅ , and WO _{3 are} shown in the following Tables 80 to 83. A preferred range of the content of each component.

Next, optional components other than the components described above will be described.

Lithium oxide (Li ₂ O) has a strong effect of lowering the glass transition temperature, and therefore, when the content thereof is increased, the mechanical workability tends to be lowered. Further, there is a tendency that chemical durability and weather resistance are lowered. Therefore, the content of Li ₂ O is preferably set to 5% or less. A preferred lower limit and a better upper limit of the content of Li ₂ O are shown in Table 84 below. The content of Li ₂ O can also be set to 0%.

Sodium oxide (Na ₂ O), potassium oxide (K ₂ O), lanthanum oxide (Rb ₂ O), and cerium oxide (Cs ₂ O) all have the effect of improving the meltability of the glass, but when their content is increased, The tendency of the glass to have thermal stability, chemical durability, weather resistance, and machinability is lowered. Therefore, the lower limit and the upper limit of the respective contents of Na ₂ O, K ₂ O, Rb ₂ O, and Cs ₂ O are preferably as shown in the following Tables 85 to 88, respectively.

In order to improve the glass's meltability while maintaining the thermal stability, chemical durability, weather resistance, and machinability of the glass, the total content of Li ₂ O, Na ₂ O, and K ₂ O (Li ₂ O+Na ₂ O+ The preferred lower limit and preferred upper limit of K ₂ O) are shown in Table 89 below.

Magnesium oxide (MgO), calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO) are all components having an effect of improving the meltability of the glass. However, when the content of these components increases, the thermal stability of the glass decreases, indicating a tendency to devitrification. Therefore, the content of each of these components is preferably set to be equal to or higher than the lower limit and lower limit shown in the following Tables 90 to 93, respectively.

In addition, in order to maintain the thermal stability of the glass, MgO, CaO, SrO The total content of BaO (MgO+CaO+SrO+BaO) is preferably set to be equal to or higher than the lower limit and lower than the upper limit shown in Table 94 below.

Aluminum oxide (Al ₂ O ₃ ) is a component having an effect of improving the chemical durability and weather resistance of the glass. However, when the content of Al ₂ O ₃ is increased, the refractive index (nd) tends to decrease, the thermal stability of the glass tends to decrease, and the meltability tends to decrease. In view of the above, the content of Al ₂ O ₃ is preferably set to be equal to or higher than the lower limit and lower than the upper limit shown in Table 95 below.

Gallium dioxide (Ga ₂ O ₃ ), indium trioxide (In ₂ O ₃ ), antimony trioxide (Sc ₂ O ₃ ), and hafnium oxide (HfO ₂ ) all have an effect of increasing the refractive index (nd). . However, these components are expensive and are not essential components for obtaining the above optical glass. Therefore, the content of each of Ga ₂ O ₃ , In ₂ O ₃ , Sc ₂ O ₃ , and HfO ₂ is preferably set to be equal to or higher than the lower limit and lower limit shown in the following Tables 96 to 99.

Antimony trioxide (Lu ₂ O ₃ ) has an effect of increasing the refractive index (nd), but it is also a component that increases the specific gravity of the glass. Further, Lu is a heavy rare earth element similarly to Gd and Yb, and therefore it is preferable to reduce the content of Lu. From the above aspects, a preferred lower limit and a preferred upper limit of the content of Lu ₂ O ₃ are shown in Table 100 below.

Cerium dioxide (GeO ₂ ) has an effect of increasing the refractive index (nd), but it is a particularly expensive component among the commonly used glass components. In order to lower the manufacturing cost of the glass, a preferred lower limit and a preferred upper limit of the content of GeO ₂ are shown in Table 101 below.

Bismuth trioxide (Bi ₂ O ₃ ) is a component that increases the refractive index (nd) and lowers the Abbe number (νd). In addition, it is a component which tends to increase the color of the glass. In order to produce a glass having the above optical characteristics and having little coloration, a preferred lower limit and a preferred upper limit of the content of Bi ₂ O ₃ are shown in Table 102 below.

In order to satisfactorily obtain the various actions and effects described above, the total content (total content) of each of the glass components described above is preferably more than 95%, more preferably more than 98%, still more preferably more than 99%, still more preferably more than 99.5%.

Among the glass components other than the glass component described above, phosphorus pentoxide (P ₂ O ₅ ) is a component that lowers the refractive index (nd) or a component that lowers the thermal stability of the glass, but may be extremely small. The introduction of the glass will increase the thermal stability of the glass. In order to produce a glass having the above optical characteristics and excellent thermal stability, a preferred lower limit and a preferred upper limit of the content of P ₂ O ₃ are shown in Table 103 below.

Cerium oxide (TeO ₂ ) is a component that increases the refractive index (nd), but since it is a toxic component, it is preferable to reduce the content of TeO ₂ . A preferred lower limit and a preferred upper limit of the content of TeO ₂ are shown in Table 104 below.

Further, in each of the above tables, a component of 0% is described in a (better) lower limit or upper limit, and the content thereof is preferably 0%. The same is true for the total content of a plurality of components.

Pb, As, Cd, Tl, Be, Se are all toxic. Therefore, it is preferred not to contain these elements, that is, it is preferable not to introduce these elements into the glass as a glass component.

U, Th, and Ra are all radioactive elements. Therefore, it is preferred not to contain these elements, that is, it is preferable not to introduce these elements into the glass as a glass component.

V, Cr, Mn, Fe, Co, Ni, Cu, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Ce increase the color of the glass or become a source of fluorescence. The element contained in the glass for the optical element is not preferable. Therefore, it is preferred not to contain these elements, that is, it is preferable not to introduce these elements into the glass as a glass component.

Sb and Sn are elements which can be optionally added as a clarifying agent.

When Sb in terms of Sb ₂ O ₃ and the glass component other than the ₂ O ₃ in the total content 100% by mass, the range of Sb is preferably added in an amount of from 0 to 0.11% by mass, more preferably 0.01 to 0.08 mass % is further preferably 0.02 to 0.05% by mass.

When the content of the glass component in terms other than the SnO ₂ SnO ₂ and the total of 100% by mass, the range of Sn is preferably added in an amount of 0 to 0.5% by mass, more preferably from 0 to 0.2 mass%, further more Good is 0% by mass.

Next, the glass characteristics common to the glass A and the glass B will be described. The glass described below refers to glass A and glass B.

<glass characteristics> (Optical properties of glass)

The glass is a glass having an Abbe number (νd) in the range of 39.5 to 41.5 and having a refractive index (nd) and an Abbe number (νd) satisfying the following formula (1).

Formula (1) nd 2.0927-0.0058×νd

A glass having an Abbe number (νd) of 39.5 or more is effective as a material for an optical element for correcting chromatic aberration. On the other hand, when the Abbe number (νd) is more than 41.5, if the refractive index is not lowered, the thermal stability of the glass is remarkably lowered, and it becomes easy to devitrify during the process of manufacturing the glass. The lower limit and the preferred upper limit of the Abbe number (νd) are shown in Table 105 below.

In the above glass, the refractive index (nd) and the Abbe number (νd) satisfy the formula (1). The Abbe number (νd) ranges from 39.5 to 41.5 and the refractive index (nd) satisfies the formula (1). The glass is a high-value glass used in the design of optical systems.

The upper limit of the refractive index (nd) is naturally determined by the composition of the glass. In order to improve the thermal stability and obtain a glass which is not easily devitrified, the refractive index (nd) preferably satisfies the following formula (2).

Formula (2) nd 2.1270-0.0058×νd

A lower limit and a better upper limit of the refractive index (nd) with respect to the Abbe number (?d) are shown in Table 106 below.

Further, the refractive index (nd) is preferably at least the lower limit and not more than the upper limit shown in Table 107 below.

(partial dispersion characteristics)

From the viewpoint of correcting chromatic aberration, when the Abbe number (νd) is fixed, the glass is preferably a glass having a relatively small dispersion.

Here, the relative partial dispersion (Pg, F) can be expressed as (ng-nF)/((g-nF)/() using the refractive index (ng), the refractive index (nF), and the refractive index (nc) in the g-line, the F-line, and the c-line. nF-nc).

In order to provide a glass suitable for high-order chromatic aberration correction, a preferred lower limit and a preferred upper limit of the relative partial dispersion (Pg, F) of the above glass are shown in Table 108 below.

(glass transition temperature)

The glass transition temperature of the above glass is not particularly limited, but is preferably 640 ° C or higher. By setting the glass transition temperature to 640 ° C or higher, it is possible to make the glass less likely to be broken when the glass is subjected to mechanical processing such as cutting, cutting, polishing, and polishing. Further, since it is not necessary to contain a large amount of components such as Li and Zn which have a strong effect of lowering the glass transition temperature, even if the content of Gd and Ta is reduced, and even if the content of Yb is further reduced, the thermal stability is easily improved.

On the other hand, when the glass transition temperature is too high, the glass must be annealed at a high temperature, and the annealing furnace is significantly consumed. Further, when molding glass, it is necessary to perform molding at a high temperature, and the consumption of a mold used for molding becomes remarkable.

In order to improve the machinability and reduce the burden on the annealing furnace and the molding die, a preferred lower limit and a preferred upper limit of the glass transition temperature are shown in Table 109 below.

(light transmission of glass)

The light transmittance of the glass, specifically, the degree of suppression of the long wavelength of the light absorption end on the short wavelength side can be evaluated by the degree of coloration (λ5). The degree of coloration (λ5) indicates a wavelength at which the spectral transmittance (including the surface reflection loss) of the glass having a thickness of 10 mm from the ultraviolet region to the visible region is 5%. Λ5 shown in the examples described later is a value measured in a wavelength region of 250 to 700 nm. The spectral transmittance refers to, for example, a spectral transmittance obtained by irradiating light onto the polished surface from the vertical direction using a glass sample having mutually parallel planes polished to a thickness of 10.0 ± 0.1 mm. In other words, Iout/Iin when the intensity of light incident on the glass sample is Iin and the intensity of light transmitted through the glass sample is Iout.

According to the degree of coloration (λ5), the absorption end of the short-wavelength side of the spectral transmittance can be quantitatively evaluated. As described above, when the lenses are bonded to each other by the ultraviolet curable adhesive in order to produce a cemented lens, the adhesive is cured by irradiating the adhesive with ultraviolet rays by the optical element. In order to more efficiently cure the ultraviolet curable adhesive, it is preferred that the absorption end on the short wavelength side of the spectral transmittance is in the short wavelength region. As an index for quantitatively evaluating the absorption end on the short-wavelength side, the degree of coloration (λ5) can be used. The above glass can be preferably adjusted by the composition as described above. Λ5 of 335 nm or less is shown, λ5 of 332 nm or less is more preferably shown, λ5 of 330 nm or less is further preferably shown, λ5 of 328 nm or less is further preferably shown, and 326 nm or less is further preferably shown. Λ5. Regarding the lower limit of λ5, 315 nm can be set as a target as an example, but the lower the value, the more preferable, and it is not particularly limited.

On the other hand, as an index of the coloring degree of glass, the coloring degree (λ70) is mentioned. Λ70 represents a wavelength at which the spectral transmittance measured by the method described in λ5 becomes 70%. In order to form a glass which is less colored, a preferable range of λ70 is 420 nm or less, a more preferable range is 400 nm or less, a still more preferable range is 390 nm or less, and a still more preferable range is 380 nm or less. The target of the lower limit of λ70 is 350 nm, but the lower the value, the more preferable, and it is not particularly limited.

Moreover, as an index of the coloring degree of glass, the coloring degree (λ80) is also mentioned. Λ80 represents a wavelength at which the spectral transmittance measured by the method described in λ5 becomes 80%. In order to form a glass which is less colored, a preferable range of λ80 is 550 nm or less, a more preferable range is 500 nm or less, a still more preferable range is 490 nm or less, and a still more preferable range is 480 nm or less. The target of the lower limit of λ80 is 355 nm, but the lower the value, the more preferable, and it is not particularly limited.

(specific gravity of glass)

In the optical element (lens) constituting the optical system, the refractive power is determined by the refractive index of the glass constituting the lens and the curvature of the optical functional surface of the lens (the surface on which the light to be controlled is incident and emitted). When it is desired to increase the curvature of the optical functional surface, the thickness of the lens also increases. As a result, the lens becomes heavier. On the other hand, if a glass having a high refractive index is used, a large refractive power can be obtained without increasing the curvature of the optical functional surface.

As described above, if the refractive index can be increased while suppressing an increase in the specific gravity of the glass, the optical element having a fixed refractive power can be made lighter.

Regarding the contribution of the refractive index (nd) to the refractive power, the ratio of the specific gravity (d) of the glass to the value (nd-1) of the refractive index (1) in the vacuum from the refractive index (nd) of the glass can be taken as the optical The indicator when the component is lighter. In other words, d/(nd-1) is used as an index for reducing the weight of the optical element, and by reducing the value, it is possible to reduce the weight of the lens.

In the glass, the proportion of Gd and Ta which contribute to the increase in specific gravity is small, and the ratio of Yb can be reduced. Therefore, the glass is a high refractive index low dispersion glass and can be made low in specific gravity. Therefore, the d/(nd-1) of the above glass can be, for example, 5.70 or less. However, when d/(nd-1) is excessively lowered, the tendency of the thermal stability of the glass to decrease is exhibited. Therefore, d/(nd-1) is preferably set to 5.00 or more. A better lower limit and a better upper limit of d/(nd-1) are shown in Table 110 below.

Further, a preferred lower limit and a preferred upper limit of the specific gravity (d) of the above glass are shown in Table 111 below. From the viewpoint of reducing the weight of the optical element made of the glass, the specific gravity (d) is preferably equal to or lower than the upper limit shown in the following Table 111. Further, in order to further improve the thermal stability of the glass, the specific gravity is preferably equal to or higher than the lower limit of the following table 111.

(liquidus temperature)

As one of the indexes of the thermal stability of glass, there is a liquidus temperature. The liquidus temperature (LT) is preferably 1300 ° C or lower, more preferably 1250 ° C or lower, in order to suppress crystallization and devitrification during glass production. The lower limit of the liquidus temperature (LT) is, for example, 1100 ° C or more, but is preferably low, and is not particularly limited.

The glass A and the glass B according to an embodiment of the present invention described above have a large refractive index (nd) and an Abbe number (νd), and are useful as a glass material for optical elements. Further, it is also possible to homogenize the glass and reduce the coloration by the composition adjustment as described above. Therefore, the above glass is suitable as an optical glass.

Next, a method of producing glass in common with glass A and glass B will be described. The glass described below refers to glass A and glass B.

<Method of Manufacturing Glass>

The glass can be obtained by weighing and compounding oxides, carbonates, sulfates, nitrates, hydroxides, and the like as raw materials in such a manner that the target glass composition can be obtained, and sufficiently mixing them to prepare a mixed batch. The material is heated and melted in a melting vessel, defoamed and stirred to prepare a molten glass which is homogeneous and does not contain bubbles, and is molded. Specifically, it can be produced by a known melting method. The above glass is a high refractive index low dispersion glass having the above optical characteristics Since glass has excellent thermal stability, it can be stably produced by a known melting method or molding method.

[Glass material for press molding, optical element blank, and method for producing the same]

Another embodiment of the present invention relates to a glass material for press molding comprising the above-described glass A or glass B; and an optical element blank comprising the above-described glass A or glass B.

According to another embodiment of the present invention, there is provided a method of producing a glass material for press molding, comprising the steps of molding the glass A or the glass B described above into a glass material for press molding; and a method for producing an optical element blank And comprising the steps of: producing an optical element blank by press-molding the above-mentioned glass material for press molding with a press molding die; and a method of manufacturing the optical element blank, comprising molding the above-mentioned glass A or glass B The step of the optical component blank.

The optical element blank refers to a shape similar to the shape of the optical element to be targeted, a polishing margin (a surface layer removed by polishing) is added to the shape of the optical element, and grinding is added as needed. The optical element base material of the remaining amount (the surface layer removed by grinding). The optical element can be completed by grinding and polishing the surface of the optical element. In one embodiment, the optical element blank can be produced by a method of press molding a molten glass (referred to as a direct pressing method) obtained by melting an appropriate amount of the glass. In another embodiment, the optical element blank can be produced by curing the molten glass obtained by melting an appropriate amount of the glass.

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

The press molding of the glass material for press molding can be carried out by a known method of pressing a glass material for press molding which is heated and softened by a press molding die. Both heating and press molding can be carried out in the atmosphere. A uniform optical element blank can be obtained by reducing the stress inside the glass by annealing after press molding.

In addition to the glass material for press molding which is used for press molding for producing an optical element blank, which is used for press forming of an optical element blank as it is, the glass material for press molding includes cutting and polishing. A glass material for press molding used for press forming by a glass gob for press molding, such as polishing or polishing. As a cutting method, there is a method in which a groove is formed in a portion to be cut at the surface of the glass sheet by a method called scribing, and a partial pressure is applied to a portion of the groove from the back surface of the surface on which the groove is formed. A method of breaking a glass plate by a part of a groove; a method of cutting a glass plate by a cutting blade, and the like. Further, as the polishing and polishing method, barrel polishing or the like can be mentioned.

The glass material for press molding can be produced, for example, as follows. That is, the molten glass is cast into a mold to form a glass plate, and the glass plate is cut into a plurality of glass sheets. Alternatively, it is also possible to mold an appropriate amount of molten glass to prepare a glass gob for press molding. It is also possible to produce an optical element blank by reheating, softening, and press-molding the glass gob for press molding. A method of producing an optical element blank by reheating, softening, and press-molding the glass relative to the direct pressing method is called a reheat pressing method.

[Optical element and its manufacturing method]

Another embodiment of the present invention relates to an optical element comprising the above-described glass A or glass B.

The above optical element is produced using the above glass. In the above optical element, one or more layers of a multilayer film such as an antireflection film may be formed on the surface of the glass.

Further, according to an embodiment of the present invention, there is provided a method of manufacturing an optical element comprising the step of fabricating an optical element by grinding and/or polishing the above-described optical element blank.

In the method for producing an optical element described above, a known method can be applied to polishing and polishing, and the surface of the optical element can be sufficiently washed and dried after the processing, whereby internal quality and surface quality can be obtained. Optical element. Thus, an optical element composed of the above glass can be obtained. As the optical element, various lenses such as a spherical lens, an aspherical lens, and a microlens, a prism, and the like can be exemplified.

Further, an optical element composed of the above glass is also suitable as a lens constituting a cemented optical element. As the glue optical element, a glue optical element (glued lens) in which lenses are glued to each other, a glue optical element in which a lens and a prism are glued together, and the like can be exemplified. For example, a glued optical element can be produced by precision machining (for example, spherical polishing) of a bonding surface of two optical elements to be bonded in such a manner that the shape thereof is reversed, and coating for adhesion An ultraviolet-curable adhesive that is bonded to a cemented lens, and after bonding, the adhesive is cured by irradiating ultraviolet rays with a lens. The above glass is preferable for producing a cemented optical element as described above. By using a variety of glass with different Abbe numbers (νd) A plurality of optical elements to be glued and glued together can be made into an element suitable for correction of chromatic aberration.

The result of the quantitative analysis of the glass composition and the glass component are expressed on the basis of the oxide, and the content of the glass component is represented by mass%. The composition expressed by mass% based on the oxide as described above can be converted into a composition represented by cation % and anion %, for example, by the following method.

In the case where N kinds of glass components are contained in the glass, the kth glass component is represented by A(k) _m O _n . Here, k is an arbitrary integer of 1 or more and N or less.

A(k) is a cation, O is oxygen, and m and n are stoichiometrically determined integers. For example, in the case where B ₂ O ₃ is represented by an oxide, m=2, n=3; in the case of SiO ₂ , m=1, n=2.

Next, the content of A(k) _m O _n is set to X (k) [% by mass]. Here, when the atomic weight of A(k) is P(k) and the atomic weight of oxygen O is Q, the molecular weight R(k) of A(k) _m O _n is R(k)=P. (k) × m + Q × n.

Further, when B=100/{Σ[m×X(k)/R(k)]}, the content (cation %) of the cationic component A(k) ^s+ is [X(k)/R(k) ] × m × B (cation %). Here, Σ means the total of m × X (k) / R (K) of k = 1 to N. m varies according to k. s is 2n/m.

Further, the molecular weight R(k) may be calculated by rounding off the fourth digit after the decimal point and using a value represented by three decimal places. Further, the molecular weights represented by oxides for several glass components and additives are shown in Table 112 below.

[Examples]

Hereinafter, the present invention will be further described based on examples. However, the present invention is not limited to the embodiment shown in the embodiment.

(Example 1)

A compound such as an oxide or a boric acid is weighed as a raw material so that a glass having a composition shown in the following Tables 113 to 114 can be obtained, and this is sufficiently mixed to prepare a batch raw material.

The batch material was placed in a platinum crucible, heated together with hydrazine to a temperature of 1350 to 1450 ° C, and the glass was melted and clarified over 2 to 3 hours. After the molten glass was stirred and homogenized, the molten glass was cast into a preheated molding die, and placed in a vicinity of the glass transition temperature, and immediately placed in the annealing furnace together with the molding die. Then, annealing was performed for about 1 hour near the glass transition temperature. After annealing, it was placed in an annealing furnace and cooled to room temperature.

When the glass produced in this manner was observed, no precipitation of crystals, bubbles, streaks, and melting of the raw material were observed. In this way, it is possible to produce a glass having high homogeneity.

Nos. 1 to 52 in Table 113 are glass A, and Nos. 1 to 52 in Table 114 are glass B.

(Comparative examples 1 to 4)

A compound such as an oxide or a boric acid was weighed as a raw material in such a manner as to obtain a glass having the respective compositions of Comparative Examples 1 to 4 shown in the following table, and the mixture was sufficiently mixed to prepare a batch raw material. 1 The same method was used to obtain the glass.

The composition of Comparative Example 1 is a composition in which the composition of the glass No. 11 of Patent Document 20 is converted into a composition of a glass represented by a cationic %.

In the comparative example 2, the composition of the glass No. 25 of the patent document 20 is converted into the composition of the glass composition represented by the cationic %.

In Comparative Example 3, the composition of the glass No. 45 of Patent Document 20 was converted into a composition of a glass composition represented by a cationic %.

In the comparative example 4, the composition of the glass No. 49 of the patent document 20 is converted into the composition of the glass composition represented by the cationic %.

The glass characteristics of the obtained glass were measured by the following methods. The measurement results are shown in the following Tables 113 to 114.

(1) Refractive index (nd), refractive index (nF), refractive index (nc), refractive index (ng), Abbe number (νd)

The refractive index (nd), refractive index (nF), refractive index (nc), and refractive index of the glass obtained by lowering the temperature at a temperature drop rate of -30 ° C / hour by the refractive index measurement method of the Japan Optical Glass Industry Association standard (ng). Use refractive index (nd), refractive index (nF), The Abbe number (νd) was calculated for each measured value of the refractive index (nc).

(2) Glass transition temperature (Tg)

The measurement was carried out by using a differential scanning calorimeter (DSC) at a temperature increase rate of 10 ° C / min.

(3) Specific gravity

The measurement was carried out by the Archimedes method.

(4) Degree of coloration (λ5), degree of coloration (λ70), degree of coloration (λ80)

A glass sample having a thickness of 10 ± 0.1 mm having two planes optically polished toward each other was used, and a light having a intensity of Iin was incident from a direction perpendicular to the polished surface by a spectrophotometer and the transmitted glass was measured. The light intensity Iout of the sample is calculated as the spectral transmittance Iout/Iin, the wavelength at which the spectral transmittance is 5% is λ5, the wavelength at which the spectral transmittance is 70% is λ70, and the spectral transmittance is changed to 80%. The wavelength is taken as λ80.

(5) Relative partial dispersion (Pg, F)

The value of nF, nc, and ng measured in the above (1) was calculated.

(6) Liquidus temperature

The glass was placed in a furnace heated to a predetermined temperature for 2 hours. After cooling, the inside of the glass was observed with a 100-fold optical microscope, and the liquidus temperature was determined depending on the presence or absence of crystals.

(Example 2)

A glass block for press molding (glass gob) was produced using the various glasses obtained in Example 1. The glass block was heated and softened in the atmosphere, and press-molded by a press molding die to prepare a lens blank (optical element blank). The produced lens blank was taken out from the press molding die, annealed, and subjected to mechanical processing including polishing to produce a spherical lens composed of various glasses produced in Example 1.

(Example 3)

The required amount of the molten glass produced in Example 1 was compression-molded by a press molding die to prepare a lens blank (optical element blank). The produced lens blank was taken out from the press molding die, annealed, and subjected to mechanical processing including polishing to produce a spherical lens composed of various glasses produced in Example 1.

(Example 4)

The molten glass produced in Example 1 was solidified to prepare a glass block (optical element blank), annealed, and subjected to mechanical processing including polishing to produce a spherical lens composed of various glasses produced in Example 1.

(Example 5)

The spherical lenses produced in Examples 2 to 4 were bonded to a spherical lens made of another glass to produce a cemented lens. The cemented surface of the spherical lens produced in Examples 2 to 4 was a convex surface, and the cemented surface of a spherical lens composed of another optical glass was a concave surface. The two cemented surfaces are formed such that the absolute values of the curvature radii of each other are equal. An ultraviolet curable adhesive for bonding an optical element is applied to the bonding surface, and the bonding surfaces of the two lenses are bonded to each other. Thereafter, the adhesive applied to the bonding surface was irradiated with ultraviolet rays by the spherical lenses produced in Examples 2 to 4 to cure the adhesive.

A cemented lens is produced as described above. The cemented strength of the cemented lens is high enough. Optical performance has also reached a sufficient level.

(Comparative Example 5)

The glass of No. 51 (hereinafter referred to as glass I) shown in Table 8 of JP-A-2014-62026 is reproduced. The λ5 of the glass of No. 51 described in Japanese Laid-Open Patent Publication No. 2014-62026 is 337 nm.

Next, in the same manner as in the above-described Example 5, a spherical lens made of glass I was produced, and it was attempted to produce a cemented lens using the produced spherical lens. However, when the ultraviolet curable adhesive applied to the bonding surface is irradiated with ultraviolet rays by the lens made of the glass I, since the ultraviolet transmittance of the glass I is low, the adhesive cannot be sufficiently cured.

(Comparative Example 6)

The cation ratio of {Zn ²⁺ /(La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ³⁺ )} of the glass A according to an embodiment of the present invention is less than 0.2.

The mass ratio of the glass B according to an embodiment of the present invention is {ZnO/(La ₂ O ₃ +Y ₂ O ₃ +Gd ₂ O ₃ +Yb ₂ O ₃ )} is less than 0.10.

On the other hand, the cation ratio of the glass of No. 6 shown in Table 1 of JP-A-2014-62026 is 0.578, and the mass ratio is 0.325.

In the glass composition of the glass of No. 6 shown in Table 1 of JP-A-2014-62026, the cation ratio is less than 0.2 and the mass ratio is less than 0.10, and the amount of Zn ²⁺ (ZnO) is decreased. The amount of reduction was distributed to the other components in such a manner that the balance of the contents of the other components did not largely change, and the composition was adjusted as shown in Tables 115 and 116 below to prepare the glass. The ratio of the glass components in Table 115 to each other is a cation ratio, and the ratio of the glass components in Table 116 is a mass ratio of the content of each component in the glass composition based on the oxide. Specifically, the glass raw material was blended, and 170 g of the blended raw material was placed in a platinum crucible, and melted and clarified at 1400 ° C for 2 hours. After the molten glass was stirred and homogenized, the molten glass was cast into a preheated molding die, left to cool to near the glass transition temperature, and then immediately placed in the annealing furnace together with the molding die. Then, annealing was performed for about 1 hour near the glass transition temperature. After annealing, it was placed in an annealing furnace and cooled to room temperature.

Thereafter, the inside of the glass was observed.

1 is a photograph of a glass evaluated in Comparative Example 6. As is apparent from Fig. 1, many crystals are precipitated in the glass, which is cloudy and loses transparency.

On the other hand, in the glass A and the glass B according to the embodiment of the present invention, crystal deposition can be suppressed by performing the composition adjustment as described above.

Finally, the above embodiments are summarized.

According to one embodiment, it is possible to provide glass A which is an oxide glass in which the total content of B ³⁺ and Si ⁴⁺ is 43 to 65% in terms of cationic %; La ³⁺ , Y ³⁺ , Gd The total content of ³⁺ and Yb ³⁺ is 25~50%; the total content of Nb ⁵⁺ , Ti ⁴⁺ , Ta ⁵⁺ and W ⁶⁺ is 3~12%; the content of Zr ⁴⁺ is 2~8%; the total content of B ³⁺ and Si ⁴⁺ with respect to La ^3+, Y ^3+, Gd ³⁺ cations and the total content of Yb ³⁺ ratio ^{{(B 3+ + Si 4+)} / (La 3+ + Y ³⁺ +Gd ³⁺ +Yb ³⁺ )} is 0.70 to 1.75; the ratio of the total content of B ³⁺ and Si ^{4+ to} the total content of Nb ⁵⁺ , Ti ⁴⁺ , Ta ⁵⁺ and W ⁶⁺ {(B ³⁺ +Si ⁴⁺ )/(Nb ⁵⁺ +Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ )} is 9.00 or less; the content of Zn ²⁺ is relative to La ³⁺ , Y ³⁺ , Gd ³ The cation ratio of {Zn ²⁺ /(La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ³⁺ )} of the total content of ⁺ and Yb ³⁺ is less than 0.2; the content of La ³⁺ is relative to La ³⁺ , Y The cation ratio of the total content of ³⁺ , Gd ³⁺ and Yb ³⁺ is {La ³⁺ /(La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ³⁺ )} is 0.50-0.95; the content of Y ³⁺ is relative The cation ratio of the total content of La ³⁺ , Y ³⁺ , Gd ³⁺ and Yb ³⁺ is {Y ³⁺ /(La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ³⁺ )} is 0.10-0.5 0; with respect to the content of Gd ³⁺ La ^3+, Y ^3+, Gd ³⁺ cations and the total content ratio of Yb ^{3+ {Gd 3+ / (La 3+ +} Y 3+ + Gd 3+ + Yb 3 ^+)} is 0.10 or less; the content of Nb ⁵⁺ cation with respect to the total content of Nb ^5+, Ti ⁴⁺ and W ⁶⁺ ratio ^{{Nb 5+ / (Nb 5+ +} Ti 4+ + W 6+)} less than 0.80; Ta ⁵⁺ content with respect to the Nb ^5+, cationic Ti ^4+, total content of Ta ⁵⁺ + Ta and W ⁶⁺ ratio ^{{Ta 5+ / (Nb 5+ +} Ti 4+ 5+ + W ⁶⁺ )} is 0.2 or less; the Abbe number (νd) ranges from 39.5 to 41.5, and the refractive index (nd) and the Abbe number (νd) satisfy the above formula (1).

Further, according to one embodiment, it is possible to provide glass B which is an oxide glass in which the total content of B ₂ O ₃ and SiO ₂ is 17.5 to 35% in terms of mass%; La ₂ O ₃ , Y ₂ The total content of O ₃ , Gd ₂ O ₃ and Yb ₂ O ₃ is 45 to 70%; the total content of Nb ₂ O ₅ , TiO ₂ , Ta ₂ O ₅ and WO ₃ is 3 to 16%; the content of ZrO ₂ is 2 to 10%; the mass ratio of the total content of B ₂ O ₃ and SiO _{2 to} the total content of 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 + Y ₂ O ₃ + Gd ₂ O ₃ + Yb ₂ O ₃ )} is 0.2 to 0.5; the total content of B ₂ O ₃ and SiO ₂ is relative to Nb ₂ O ₅ , TiO ₂ , The mass ratio of the total content of Ta ₂ O ₅ and WO ₃ is {(B ₂ O ₃ + SiO ₂ ) / (Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ + WO ₃ )} is 2.8 or less; the content of ZnO is relatively to _{La 2 O 3, Y 2 O} 3, Gd mass total content ₂ O ₃ and Yb ₂ O ₃ ratio _{{ZnO / (La 2 O 3} + Y 2 O 3 + Gd 2 O 3 + Yb 2 O 3) } is less than 0.10; the content of La ₂ O ₃ with respect to La ₂ O _3, the quality of the total content of _{Y 2 O 3, Gd 2 O} 3 and Yb ₂ O ₃ ratio _{{La 2 O 3 / (La} 2 O 3 + _{Y 2 O 3 + Gd 2 O} 3 + Yb 2 O 3)} 0.55 to 0.98; the content of Y ₂ O ₃ For the _{La 2 O 3, Y 2 O} 3, Gd mass total content ₂ O ₃ and Yb ₂ O ₃ ratio of _{{Y 2 O 3 / (La} 2 O 3 + Y 2 O 3 + Gd 2 O 3 + Yb 2 O _3)} 0.02 to 0.45; the content of Gd ₂ O ₃ with respect to _{La 2 O 3, Y 2 O} 3, Gd mass total content ₂ O ₃ and Yb ₂ O ₃ ratio of {Gd ₂ O ₃ / (La _{2 O 3 + Y 2 O 3} + Gd 2 O 3 + Yb 2 O 3)} is 0.10 or less; of Nb ₂ O ₅ content with respect to the Nb ₂ O _5, mass of the total content of TiO ₂ and WO ₃ ratio {Nb _{2 O 5 / (Nb 2 O} 5 + TiO 2 + WO 3)} is 0.81 or more; the content of Ta ₂ O ₅ with respect to the Nb ₂ O _5, TiO _2, mass of Ta ₂ O ₅ and WO total content ₃ ratio {Ta ₂ O ₅ /(Nb ₂ O ₅ +TiO ₂ +Ta ₂ O ₅ +WO ₃ )} is 0.3 or less; Abbe number (νd) ranges from 39.5 to 41.5, and refractive index (nd) and Abbe The number (νd) satisfies the above formula (1).

The above glass is a glass satisfying the formula (1) and is a high refractive index low dispersion glass useful in an optical system. In the above glass, the ratio of Gd and Ta in the glass composition represented by the cationic % or the ratio of Gd ₂ O ₃ and Ta ₂ O ₅ in the glass composition expressed by mass% is lowered, and thus it is stable. By supplying the above-mentioned content, total content, and cation ratio or mass ratio, high thermal stability can be obtained and the long wavelength of the light absorption end on the short-wavelength side can be suppressed.

In one embodiment, the content of Gd ³⁺ in the glass A is preferably 3 cationic % or less, and the content of Gd ₂ O ₃ in the glass B is preferably 6% by mass or less from the viewpoint of stably supplying the glass.

In one embodiment, the content of Ta ⁵⁺ in the glass A is preferably 3.0 cation % or less, and the content of Ta ₂ O ₅ in the glass B is preferably 5% by mass or less from the viewpoint of stably supplying the glass.

In one embodiment, with respect to glass A and glass B, it is preferred The long wavelength of the light absorption end on the short-wavelength side of the glass is suppressed so that the degree of coloration (λ5) is 335 nm or less.

The glass material for press molding, the optical element blank, and the optical element can be produced from the glass A or the glass B described above. That is, according to another embodiment, a glass material for press molding composed of glass A or glass B, an optical element blank, and an optical element can be provided.

Further, according to another embodiment, a method for producing a glass material for press molding including a step of molding glass A or glass B into a glass material for press molding may be provided.

Further, according to another embodiment, there is provided a method of producing an optical element blank comprising the step of producing an optical element blank by press-molding the above-mentioned glass material for press molding using a press molding die.

Further, according to another embodiment, a method of manufacturing an optical element blank including the step of molding glass A or glass B into an optical element blank can be provided.

Further, according to another embodiment, there is provided a method of manufacturing an optical element comprising the step of fabricating an optical element by grinding and/or polishing the optical element blank.

It is to be understood that the embodiments disclosed herein are illustrative and not restrictive. The scope of the present invention is defined by the scope of the claims, and is intended to be

For example, the glass of one embodiment of the present invention can be obtained by subjecting the glass composition exemplified above to the composition adjustment described in the specification.

In addition, it is of course possible to arbitrarily combine two or more of the items described as an example or a preferred range in the specification.

In addition, sometimes certain glasses conform to both glass A and glass B.

[Industry Utilization]

The invention is useful in the field of manufacture of various optical components.

Claims (10)

A glass which is an oxide glass, expressed as a cationic %, and a total content of B ³⁺ and Si ⁴⁺ is 43 to 65%; a total content of La ³⁺ , Y ³⁺ , Gd ³⁺ and Yb ³⁺ is 25~50%; the total content of Nb ⁵⁺ , Ti ⁴⁺ , Ta ⁵⁺ and W ⁶⁺ is 3~12%; and the content of Zr ⁴⁺ is 2~8%; the total of B ³⁺ and Si ⁴⁺ The ratio of the cation to the total content of La ³⁺ , Y ³⁺ , Gd ³⁺ and Yb ³⁺ is {(B ³⁺ +Si ⁴⁺ )/(La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ^{3 +} )} is 0.70 to 1.75; the total content of B ³⁺ and Si ⁴⁺ is cation ratio to the total content of Nb ⁵⁺ , Ti ⁴⁺ , Ta ⁵⁺ and W ⁶⁺ {(B ³⁺ +Si ^{4+ ) / (Nb 5+ + Ti 4+} + Ta 5+ + W 6+)} is 9.00 or less; Zn ²⁺ content with respect to the La ^3+, the total content of Y ^3+, Gd ³⁺ and Yb ³⁺ is The cation ratio {Zn ²⁺ /(La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ³⁺ )} is less than 0.2; the content of La ³⁺ is relative to La ³⁺ , Y ³⁺ , Gd ³⁺ and Yb ^{3 +} cation total content ratio ^{{La 3+ / (La 3+ +} Y 3+ + Gd 3+ + Yb 3+)} 0.50 to 0.95; with respect to the content of Y ³⁺ La ^3+, Y ^3+, The cation ratio of the total content of Gd ³⁺ and Yb ³⁺ is {Y ³⁺ /(La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ³⁺ )} is 0.10 to 0.50; the content of Gd ³⁺ is relative to La ^{3 +} , Y ³ The cation ratio of the total content of ⁺ , Gd ³⁺ and Yb ³⁺ is {Gd ³⁺ /(La ³⁺ +Y ³⁺ +Gd ³⁺ +Yb ³⁺ )} is 0.10 or less; the content of Nb ⁵⁺ is relative to Nb The cation ratio of {Nb ⁵⁺ /(Nb ⁵⁺ +Ti ⁴⁺ +W ⁶⁺ )} of the total content of ⁵⁺ , Ti ⁴⁺ and W ⁶⁺ is 0.80 or more; the content of Ta ⁵⁺ is relative to Nb ⁵⁺ , The cation ratio of the total content of Ti ⁴⁺ , Ta ⁵⁺ and W ⁶⁺ is {Ta ⁵⁺ /(Nb ⁵⁺ + Ti ⁴⁺ +Ta ⁵⁺ +W ⁶⁺ )} is 0.2 or less; Abbe number (νd) The range is 39.5~41.5, and the refractive index (nd) and the Abbe number (νd) satisfy the following formula: nd 2.0927-0.0058×νd. The glass according to claim 1, wherein the content of Gd ³⁺ is 3 cationic % or less. The glass according to claim 1, wherein the content of Ta ⁵⁺ is 3.0 cation % or less. A glass, the glass is an oxide glass, by mass%, B ₂ O ₃ and the total content of SiO ₂ is _{17.5 ~ 35%; La 2 O} 3, Y 2 O 3, Gd 2 O 3 and Yb ₂ O ₃ total content of _{45 ~ 70%; Nb 2 O} 5, TiO 2, Ta total content ₂ O ₅ and WO ₃ is 3 to 16%; the content of ZrO ₂ of _{2 ~ 10%; B 2 O} 3 and SiO ₂ Mass ratio of the total content to the total content of 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 + Y ₂ O ₃ + Gd ₂ O ₃ + Yb ₂ O ₃ )} is 0.2 to 0.5; the total content of B ₂ O ₃ and SiO ₂ is relative to the mass of the total content of Nb ₂ O ₅ , TiO ₂ , Ta ₂ O ₅ and WO ₃ The ratio of {(B ₂ O ₃ + SiO ₂ ) / (Nb ₂ O ₅ + TiO ₂ + Ta ₂ O ₅ + WO ₃ )} is 2.8 or less; the content of ZnO is relative to La ₂ O ₃ , Y ₂ O ₃ , Gd The mass ratio of the total content of ₂ O ₃ and Yb ₂ O ₃ is {ZnO/(La ₂ O ₃ +Y ₂ O ₃ +Gd ₂ O ₃ +Yb ₂ O ₃ )} is less than 0.10; the content of La ₂ O ₃ is relatively Mass ratio of total content of La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ and Yb ₂ O ₃ {La ₂ O ₃ /(La ₂ O ₃ +Y ₂ O ₃ +Gd ₂ O ₃ +Yb ₂ O ₃ )} is 0.55 to 0.98; the content of Y ₂ O ₃ is relative to that of La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ and Yb ₂ O ₃ The mass ratio of the total content is {Y ₂ O ₃ /(La ₂ O ₃ +Y ₂ O ₃ +Gd ₂ O ₃ +Yb ₂ O ₃ )} is 0.02 to 0.45; the content of Gd ₂ O ₃ is relative to La ₂ O ₃ The mass ratio of the total content of Y ₂ O ₃ , Gd ₂ O ₃ and Yb ₂ O ₃ is {Gd ₂ O ₃ /(La ₂ O ₃ +Y ₂ O ₃ +Gd ₂ O ₃ +Yb ₂ O ₃ )}. 0.10; of Nb ₂ O ₅ content with respect to the Nb ₂ O _5, by mass TiO total content ₂ and WO ₃ ratio _{{Nb 2 O 5 / (Nb} 2 O 5 + TiO 2 + WO 3)} is 0.81 or more; content of Ta ₂ O ₅ with respect to the Nb ₂ O _{5, 2} mass of the total content of Ta ₂ O ₅ and WO ₃ is TiO, than _{{Ta 2 O 5 / (Nb} 2 O 5 + TiO 2 + Ta 2 O 5 + WO ₃ )} is 0.3 or less; the Abbe number (νd) ranges from 39.5 to 41.5, and the refractive index (nd) and the Abbe number (νd) satisfy the following formula: nd 2.0927-0.0058×νd. The glass according to claim 4, wherein the content of Gd ₂ O ₃ is 6% by mass or less. The glass according to claim 4, wherein the content of Ta ₂ O ₅ is 5% by mass or less. The glass according to any one of claims 1 to 6, wherein the degree of coloration (λ5) is 335 nm or less. A glass material for press molding, comprising the glass according to any one of claims 1 to 6. An optical element blank comprising the glass of any one of claims 1 to 6. An optical element comprising the glass of any one of claims 1 to 6.