CN104936916A - Optical glass - Google Patents

Abstract

The present invention provides an optical glass that contains no environmentally undesirable components, easily achieves a low glass transition temperature, exhibits excellent weather resistance and chemical durability, and exhibits excellent transmittance in the visible and near-ultraviolet regions. This optical glass is characterized by containing, by mol%, 43.5 to 80% SnO and 0.1 to 29.9% _P₂O₅ + _{B₂O₃ + SiO₂ ,} and is substantially _free of lead and arsenic. The _P₂O₅ content is preferably 0.1 to 29.5%.

Description

Optical glass

technical field

The present invention relates to optical glass. More specifically, it relates to optical glass suitable for optical pick-up tube lenses of various optical disk systems, video cameras, general camera photography lenses, and the like.

Background technique

Generally, optical pickup tube lenses for CD, MD, DVD, and other various optical disc systems, video cameras, and photography lenses for general cameras are produced by the following operations.

First, raw material powder adjusted to a desired composition is melted. Next, molten glass is dropped from the tip of the nozzle to produce droplet-shaped glass (droplet forming), and if necessary, ground, polished, and washed to produce precast glass. Or the molten glass is quenched and cast, and a glass ingot is made at one time, which is ground, ground, and washed to make prefabricated glass. Next, the prefabricated glass is heated and softened, and it is press-molded with a precision-processed mold, and the surface shape of the mold is transferred to the glass to produce a lens. Such a molding method is generally called compression molding (or precision pressure molding).

In the compression molding method, in order to suppress the deterioration of the mold and precisely mold the lens, glass having a yield point or a glass transition temperature as low as possible is required, and various glasses have been proposed.

Generally, in order to produce an optical glass having a low yield point, it is necessary to contain a large amount of components such as alkali components that cause a decrease in the refractive index, weather resistance, or chemical durability. Therefore, bismuth-based glasses and phosphate-based glasses have been proposed as glasses capable of achieving a low glass transition temperature even if the content of alkali components and the like is small (for example, refer to Patent Documents 1 and 2).

prior art literature

patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2007-106625

Patent Document 2: Japanese Patent Application Laid-Open No. 10-297936

Contents of the invention

The problem to be solved by the invention

Patent Document ₁ describes a _{Bi2O3 -} B2O3 _{- SiO2 -} based glass having a low glass transition temperature _of about 400°C. Transmittance. In addition, in Patent Document 2, a SnO-PbO-P ₂ O ₅ -based glass is described as a glass having a low glass transition temperature of 300° C. or lower, but this glass contains a lead component as an essential component, so it is not environmentally friendly. preferred.

Therefore, an object of the present invention is to provide an optical glass that does not contain environmentally unfavorable components, can easily achieve a low glass transition temperature, has excellent weather resistance and chemical durability, and has excellent transmittance in the visible region or near ultraviolet region.

method used to solve the problem

<First aspect of the present invention>

The optical glass according to the first aspect of the present invention is characterized by containing 43.5 to 80% of SnO and 0.1 to 29.9% of P ₂ O ₅ +B ₂ O ₃ +SiO ₂ in mole %, and substantially free of lead and arsenic components.

The optical glass according to the first aspect of the present invention contains a large amount of SnO in the glass composition, so it is easy to achieve high refractive index characteristics and is also excellent in weather resistance and chemical durability. In addition, during press molding, it is difficult to generate devitrified substances that inhibit transparency.

The optical glass according to the first aspect of the present invention contains P ₂ O ₅ , B ₂ O ₃ or SiO ₂ as an essential component in addition to SnO, so coloring hardly occurs, and the transmittance in the visible region or the near ultraviolet region is excellent. In addition, the optical glass according to the first aspect of the present invention is environmentally preferable glass because it does not substantially contain lead components and arsenic components which are harmful components.

In addition, in the first aspect of the present invention, "substantially free of lead components and arsenic components" means that these components are not intentionally contained in the glass, and it does not mean that unavoidable impurities are completely excluded. Objectively speaking, it means that the contents of these components including impurities are each less than 0.1% in mol%.

The content of P ₂ O ₅ is preferably 0.1 to 29.5%.

According to this constitution, glass having a low glass transition temperature can be easily obtained.

SnO/(P ₂ O ₅ +B ₂ O ₃ +SiO ₂ ) is preferably 1.5 or more in molar ratio.

According to this configuration, glass having high refractive index characteristics and excellent weather resistance and chemical durability can be easily obtained.

In mol%, it is preferable to further contain 0 to 25% of CaO+SrO+BaO+MgO+ZnO.

According to this constitution, glass excellent in devitrification resistance can be easily obtained.

It is preferable to further contain 0 to 10% of Al ₂ O ₃ +Zr ₂ O in mol%.

According to this configuration, glass excellent in weather resistance and chemical durability can be easily obtained.

The yield point is preferably 500°C or lower.

According to this configuration, press molding at low temperature can be performed, mold contamination due to mold oxidation and volatilization of glass components can be suppressed, and problems such as fusion of glass and mold can be suppressed.

The water resistance based on JOGIS is preferably grade 2 or higher.

The refractive index (nd) is preferably 1.6 or more, and the Abbe number (νd) is preferably 40 or less.

The Abbe number (νd) and the partial dispersion ratio (θg, F) preferably satisfy the relationship of (θg, F)≦−0.0047×(νd)+0.76.

In optical equipment, chromatic aberration is generally corrected by using an optical lens made of glass with low dispersion and a large partial dispersion ratio in combination with an optical lens made of glass with high dispersion and a small partial dispersion ratio. The optical glass according to the first aspect of the present invention satisfies the above-mentioned relationship between the Abbe number and the partial dispersion ratio, thereby easily achieving high dispersion and low partial dispersion ratio optical properties, and making it easy to produce an optical device excellent in chromatic aberration.

Preferably the degree of coloration λ ₇₀ is less than 500 nm.

When the glass coloration degree _λ70 satisfies the above-mentioned range, it is possible to obtain glass having excellent transmittance in the visible region or the near-ultraviolet region and suitable for optical elements such as various optical lenses. In addition, in the first aspect of the present invention, the "degree of coloration λ ₇₀ " means a wavelength at which the transmittance becomes 70% in the transmittance curve.

Preferably used for optical lenses.

Preferred for compression molding.

The optical element according to the first aspect of the present invention is characterized in that any of the above-mentioned optical glasses is used.

<The second aspect of the present invention>

The optical glass according to the second aspect of the present invention is characterized by containing 23.5 to 85% of SnO, 0.1 to 49.9% of P ₂ O ₅ , 0 to 2% of ZrO ₂ , and 0.1 to 20% of La in mole percent. ₂ O ₃ +Gd ₂ O ₃ +Ta ₂ O ₅ +WO ₃ +Nb ₂ O ₅ +TiO ₂ +Y ₂ O ₃ +Yb ₂ O ₃ +GeO ₂ and 0~1% MgO+CaO+SrO+BaO , and substantially free of lead and arsenic.

The optical glass according to the second aspect of the present invention contains a large amount of SnO in the glass composition, so it is easy to achieve high refractive index characteristics and is also excellent in weather resistance and chemical durability. In addition, during press molding, it is difficult to generate devitrified substances that inhibit transparency. Moreover, since the optical glass according to the second aspect of the present invention contains P ₂ O ₅ as an essential component in addition to SnO, it is excellent in light transmittance in the visible region or near ultraviolet region. The optical glass of the second aspect of the present invention contains La ₂ O ₃ , Gd ₂ O ₃ , Ta ₂ O ₅ , WO ₃ , Nb ₂ O ₅ , TiO ₂ , Y ₂ O ₃ , Yb ₂ O ₃ and GeO ₂ At least one of them is an essential component, so it is easy to achieve optical characteristics of high refractive index and high dispersion.

In addition, the optical glass according to the second aspect of the present invention is environmentally preferable glass because it does not substantially contain lead components and arsenic components which are harmful components. In the second aspect of the present invention, "substantially free of lead components and arsenic components" means that these components are not intentionally contained in the glass, and it does not mean that unavoidable impurities are completely excluded. Objectively speaking, it means that the contents of these components including impurities are each less than 0.1% in mol%.

The optical glass according to the second aspect of the present invention preferably contains 0 to 10% of Li ₂ O+Na ₂ O+K ₂ O in mol%.

The optical glass according to the second aspect of the present invention preferably contains 0 to 10% of B ₂ O ₃ +ZnO in mol%.

The optical glass according to the second aspect of the present invention may contain 0.01 to 1% of Cl+S+Br in mol%.

The optical glass according to the second aspect of the present invention preferably has a yield point of 500°C or lower.

The optical glass according to the second aspect of the present invention preferably has a JOGIS water resistance of grade 3 or higher.

The optical glass according to the second aspect of the present invention preferably has a refractive index of 1.6 or more and an Abbe number of 40 or less.

By satisfying the above-mentioned optical characteristics, the chromatic dispersion is reduced, so it is suitable as an optical lens for high-performance and compact optical devices.

In the optical glass according to the second aspect of the present invention, it is preferable that the Abbe number (νd) and the partial dispersion ratio (θg, F) satisfy the relationship of (θg, F)≤-0.0047×(νd)+0.76.

In optical equipment, chromatic aberration is generally corrected by using an optical lens made of glass with low dispersion and a large partial dispersion ratio in combination with an optical lens made of glass with high dispersion and a small partial dispersion ratio. The optical glass according to the second aspect of the present invention satisfies the above-mentioned relationship between the Abbe number and the partial dispersion ratio, thereby easily achieving high dispersion and low partial dispersion ratio optical properties, and making it easy to produce an optical device excellent in chromatic aberration.

In the optical glass according to the second aspect of the present invention, it is preferable that the degree of coloring λ ₇₀ is less than 500 nm. In addition, in the second aspect of the present invention, the "degree of coloration λ ₇₀ " means the shortest wavelength at which the light transmittance becomes 70% in the light transmittance curve.

The optical glass according to the second aspect of the present invention is preferably used for an optical lens.

The optical glass according to the second aspect of the present invention is preferably used for press molding.

An optical element according to a second aspect of the present invention is characterized in that the above-mentioned optical glass is used.

The effect of the invention

According to the present invention, it is possible to provide an optical glass that does not contain environmentally unfavorable components, can easily achieve a low glass transition temperature, has excellent weather resistance and chemical durability, and has excellent transmittance in the visible region or near ultraviolet region.

Detailed ways

<First aspect of the present invention>

The optical glass according to the first aspect of the present invention is characterized by containing 43.5 to 80% of SnO and 0.1 to 29.9% of P ₂ O ₅ +B ₂ O ₃ +SiO ₂ in mol%, and substantially free of lead components and arsenic components. Hereinafter, the reason for specifying each component content as mentioned above is demonstrated. In addition, "%" means "mol%" in the following description about content of each component, unless otherwise specified.

SnO is an essential component for achieving high refractive index and highly dispersed optical properties and improving chemical durability, and also has an effect of reducing the partial dispersion ratio. The content of SnO is 43.5-80%, preferably 43.5-70%, more preferably 45-69%, still more preferably 50-68%, particularly preferably 55-67%, most preferably 60-66%. When the content of SnO is too small, it becomes difficult to achieve high refractive index characteristics, and weather resistance and chemical durability tend to decrease. On the other hand, when there is too much content of SnO, vitrification becomes difficult and devitrification resistance tends to fall.

P ₂ O ₅ , B ₂ O ₃ and SiO ₂ are components of the glass skeleton. In addition, these components have an effect of increasing the transmittance, and especially have a high effect of suppressing a decrease in the transmittance near the ultraviolet region. Especially in the case of glass with a high refractive index, the effect of improving the transmittance by these components is easily obtained. In addition, it also has the effect of suppressing devitrification. The total content of P ₂ O ₅ , B ₂ O ₃ and SiO ₂ is 0.1 to 29.9%, preferably 10 to 29.5%, more preferably 12.5 to 29%, still more preferably 15 to 28.5%, particularly preferably 20-27%. When the content of these components is too small, it is difficult to obtain the above-mentioned effects. On the other hand, if the content of these components is too large, the content of SnO becomes relatively small, and the refractive index tends to decrease.

In addition, preferable ranges of the respective component contents of P ₂ O ₅ , B ₂ O ₃ and SiO ₂ are as follows.

The content of P ₂ O ₅ is preferably 0 to 29.5%, more preferably 0.1 to 29%, still more preferably 3 to 27.5%, particularly preferably 5 to 26%, most preferably 10 to 25%. When there is too much content of _P2O5 , a refractive index will _fall easily. In addition, weather resistance and chemical durability tend to decrease. In addition, by positively adding P ₂ O ₅ , glass with a low yield point and glass with little devitrification can be easily obtained, and glass with a small Young's modulus can also be easily obtained.

B ₂ O ₃ is more effective in suppressing devitrification than SiO ₂ and Al ₂ O ₃ . The content of B ₂ O ₃ is preferably 0 to 20%, more preferably 0.1 to 15%, still more preferably 1 to 10%, particularly preferably 3 to 7.5%, most preferably 4 to 7%. When there is too much content _of B2O3, a refractive index will _fall easily. In addition, weather resistance and chemical durability tend to decrease.

The content of SiO ₂ is preferably 0-20%, more preferably 0.1-15%, still more preferably 1-10%, particularly preferably 3-7.5%, most preferably 4-7%. When there is too much content of _SiO2 , a refractive index will fall easily. In addition, streaks and bubbles caused by undissolved glass remain in the glass, and there is a possibility that the quality required as glass for optical lenses and the like cannot be satisfied.

In the first aspect of the present invention, in order to obtain glass excellent in weather resistance and chemical durability, SnO/(P ₂ O ₅ +B ₂ O ₃ +SiO ₂ ) is preferably 1.5 or more, more preferably 1.7 or more, more preferably 1.9 or more, particularly preferably 2 or more, most preferably 2.4 or more. In addition, the upper limit is not particularly limited, but if the ratio is too large, SnO tends to be precipitated as pits, so it is preferably 9 or less, more preferably 7 or less, and still more preferably 5 or less.

In the first aspect of the present invention, in order to obtain glass having excellent weather resistance and a high refractive index, the content of B ₂ O ₃ +SiO ₂ is preferably 0 to 30%, more preferably 0 to 20%, and still more preferably 0%. ~10%.

Moreover, by containing _P2O5 as an essential component, and containing at least ₁ sort ₍ s ₎ selected from B2O3 and _SiO2 as an essential component, it becomes easy to obtain the glass excellent in devitrification resistance. In this case, even if SnO is contained in a large amount, excellent devitrification resistance and weather resistance are easily achieved. Therefore, higher refraction can be realized. Specific glass composition ranges at this time include 70 to 80% (excluding 70%, preferably 70.1 to 79%, more preferably 70.5 to 78%, and still more preferably 71 to 77%) of SnO in mole percent. , 0.1 to 29.9% (excluding 29.9%, preferably 10 to 29.5%, more preferably 15 to 29%, more preferably 20 to 28%) of P ₂ O ₅ , and 0.1% or more (preferably 0.15% or more, more B ₂ O ₃ +SiO ₂ glass of 0.2% or more) is preferable. In addition, if the content of B ₂ O ₃ +SiO ₂ is too large in the above composition range, it is difficult to vitrify or obtain the desired high refractive index characteristics, so it is preferably 0.9% or less, more preferably 0.8% or less.

The optical glass according to the first aspect of the present invention may contain the following components in addition to the above components.

Alkaline earth metal oxides (RO) such as CaO, SrO, and BaO, MgO, and ZnO are components that function as a flux. In addition, it has the effect of improving weather resistance, suppressing elution of glass components in various cleaning solutions such as polishing water, and suppressing deterioration of glass surfaces in high-temperature and high-humidity conditions. However, when the content of these components is too large, the liquidus temperature rises (the liquidus viscosity falls), and devitrified substances tend to be easily precipitated in the melting or molding process. As a result, mass production tends to become difficult. In addition, these components have a characteristic that they do not greatly vary the refractive index and Abbe's number. In view of the above, the total content of CaO, SrO, BaO, MgO and ZnO is preferably 0-25%, more preferably 0-20%, still more preferably 0-10%, particularly preferably 0.1-10%.

In addition, the preferable content of each component is as follows.

CaO is a component effective in improving weather resistance, and is particularly effective in improving water resistance and alkali resistance. However, when there is too much content, it becomes easy to color. Therefore, the content of CaO is preferably 0 to 25%, more preferably 0 to 20%, and still more preferably 0.1 to 10%.

SrO is a component that increases the refractive index. Moreover, compared with CaO, the effect of improving weather resistance, such as water resistance and alkali resistance, is high. Therefore, glass excellent in weather resistance can be easily obtained by positively containing SrO. However, when there is too much content, it becomes easy to color. Therefore, the content of SrO is preferably 0 to 25%, more preferably 0 to 20%, and still more preferably 0.1 to 10%.

BaO has a smaller increase in liquidus temperature than CaO, and has a high effect of improving water resistance and alkali resistance. However, when there is too much content, it becomes easy to color. Therefore, the content of BaO is preferably 0 to 25%, more preferably 0 to 20%, and still more preferably 0.1 to 10%.

MgO is a component that increases the refractive index. Moreover, compared with CaO, the effect of improving weather resistance, such as water resistance and alkali resistance, is high. Therefore, by positively containing MgO, glass excellent in weather resistance can be easily obtained. However, when there is too much content, it becomes easy to color. Therefore, the content of MgO is preferably 0 to 25%, more preferably 0 to 20%, and still more preferably 0.1 to 10%.

ZnO is a component that hardly lowers the refractive index and can lower the viscosity. Therefore, it is possible to obtain glass that has a low yield point and is difficult to fuse with a mold. In addition, it also has an effect of improving weather resistance. In addition, since the devitrification tendency is not strong compared with CaO, SrO, BaO, and MgO, homogeneous glass can be obtained even if it is contained in a relatively large amount. In addition, ZnO is also a component that is difficult to color glass. The content of ZnO is preferably 0 to 25%, more preferably 0 to 20%, and still more preferably 0.1 to 10%. When there is too much content of ZnO, it exists in the tendency for weather resistance to fall conversely. In addition, it is difficult to obtain high refractive index and high dispersion optical properties.

In the first aspect of the present invention, in order to obtain glass having excellent weather resistance and a high refractive index, the content of B ₂ O ₃ +ZnO is preferably 0 to 20%, more preferably 0 to 10%, and still more preferably 0.1 to 10%. 5%.

Li ₂ O is a component that has the greatest effect of lowering the softening point among alkali metal oxides, and has a small increase in liquidus temperature. In addition, it has the effect of reducing the partial dispersion ratio. Furthermore, the refractive index can be _improved by _substitution with _B2O3 , _SiO2 , or _Al2O3 . However, since Li ₂ O has a strong phase separation property, when the content thereof is too large, the liquidus temperature rises, devitrified substances tend to be easily precipitated, and workability tends to decrease. In addition, Li ₂ O tends to lower the chemical durability and lower the transmittance. Therefore, the content of Li ₂ O is preferably 0 to 25%, more preferably 0 to 20%, and still more preferably 0.1 to 10%.

Na ₂ O and Li ₂ O also have the effect of lowering the softening point. In addition, the refractive index can be increased by substitution with B ₂ O ₃ , SiO ₂ or Al ₂ O ₃ . In addition, it has the effect of reducing the partial dispersion ratio. However, when the content is too large, the refractive index tends to be significantly lowered or the generation of streaks tends to be promoted. In addition, the liquidus temperature rises, and devitrified substances tend to precipitate in the glass. Therefore, the content of Na ₂ O is preferably 0 to 25%, more preferably 0 to 20%, and still more preferably 0.1 to 10%.

K ₂ O also has the effect of lowering the softening point similarly to Li ₂ O. In addition, the refractive index can be increased by substitution with B ₂ O ₃ , SiO ₂ or Al ₂ O ₃ . In addition, it also has the effect of reducing the partial dispersion ratio. However, when the content is too large, the refractive index tends to decrease significantly, or the weather resistance tends to decrease. In addition, the liquidus temperature rises, and devitrified substances tend to precipitate in the glass. Therefore, the content of K ₂ O is preferably 0 to 25%, more preferably 0 to 20%, and still more preferably 0.1 to 10%.

In addition, the total amount of Li ₂ O, Na ₂ O, and K ₂ O is preferably 0 to 25%, more preferably 0 to 20%, and still more preferably 0.1 to 10%. When the total amount of these components is too large, devitrification tends to occur, and chemical durability also tends to fall. In addition, it is difficult to obtain desired optical characteristics. There is also a tendency for the transmittance to decrease.

Al ₂ O ₃ is a component capable of constituting a glass skeleton together with SiO ₂ and B ₂ O ₃ . In addition, it has the effect of improving weather resistance, especially the effect of suppressing selective elution of components such as P ₂ O ₅ , B ₂ O ₃ , and alkali metal oxides in the glass into water is large. In addition, it has the effect of increasing Young's modulus and reducing the coefficient of thermal expansion. The content of Al ₂ O ₃ is preferably 0 to 10%, more preferably 0.1 to 5%. When the content of Al ₂ O ₃ is too large, devitrification tends to occur. In addition, the melting temperature becomes high, and streaks and bubbles due to undissolved tend to remain in the glass. As a result, there is a possibility that the quality required as glass for optical lenses and the like cannot be satisfied. In addition, there is a tendency for the transmittance to decrease.

In the first aspect of the present invention, in order to obtain a glass having excellent weather resistance and a high refractive index, the content of SiO ₂ +Al ₂ O ₃ is preferably 0 to 20%, more preferably 0 to 10%, and still more preferably 0.1 ~5%.

ZrO ₂ acts as an intermediate oxide, forms a glass skeleton, and has an effect of improving weather resistance. In particular, the effect of suppressing selective elution of components such as P ₂ O ₅ , B ₂ O ₃ , and alkali metal oxides in glass into water is large. The content of ZrO ₂ is preferably 0 to 10%, more preferably 0.1 to 5%. When the content of ZrO ₂ is too large, devitrification tends to occur. In addition, the melting temperature becomes high, and streaks and bubbles due to undissolved tend to remain in the glass. As a result, there is a possibility that the quality required as glass for optical lenses and the like cannot be satisfied. In addition, there is a tendency for the transmittance to decrease.

In addition, in order to obtain glass excellent in weather resistance and chemical durability, the content of Al ₂ O ₃ +ZrO ₂ is preferably 0 to 10%, more preferably 0.1 to 5%.

La ₂ O ₃ and Gd ₂ O ₃ are components that hardly decrease the transmittance and increase the refractive index. However, when the content is too large, it becomes difficult to obtain a highly dispersed glass while devitrification resistance falls. Therefore, the content of these components is preferably 0 to 25%, more preferably 0.1 to 20%, and still more preferably 1 to 10%.

Ta ₂ O ₅ , WO ₃ , and Nb ₂ O ₅ have the effects of hardly lowering the transmittance, increasing the refractive index, and dispersing. However, when there is too much content, devitrification resistance will fall easily. Therefore, the content of these components is preferably 0 to 25%, more preferably 0.1 to 20%, and still more preferably 1 to 10%.

TiO ₂ is a component that has the effect of increasing the refractive index and dispersion. Moreover, it is a component effective in improving _{devitrification} resistance compared with _Nb2O5 and _WO3 . However, when the content is too large, the transmittance tends to decrease. In particular, when Fe components are contained in glass as impurities in a large amount (for example, 20 ppm or more), the transmittance tends to decrease significantly. Moreover, devitrification resistance falls easily. Therefore, the content of TiO ₂ is preferably 0 to 25%, more preferably 0.1 to 20%, and still more preferably 1 to 10%.

Y ₂ O ₃ , Yb ₂ O ₃ , GeO ₂ , and Bi ₂ O ₃ , like Ta ₂ O ₅ , have the effects of hardly lowering the transmittance, increasing the refractive index, and dispersing. However, when there is too much content, devitrification resistance will fall easily. Therefore, the content of these components is preferably 0 to 25%, more preferably 0.1 to 20%, and still more preferably 1 to 10%.

TeO ₂ has the effect of hardly lowering the transmittance, increasing the refractive index, and dispersing. In addition, it has the effect of reducing the partial dispersion ratio. However, when there is too much content, devitrification resistance will fall easily. Therefore, the content of TeO ₂ is preferably 0 to 25%, more preferably 0.1 to 20%, and still more preferably 1 to 10%.

In addition, in order to obtain a glass having a desired refractive index and Abbe number, La ₂ O ₃ +Gd ₂ O ₃ +Ta ₂ O ₅ +WO ₃ +Nb ₂ O ₅ +TiO ₂ +Y ₂ O ₃ +Yb ₂ The content of O ₃ +GeO ₂ +Bi ₂ O ₃ +TeO ₂ is preferably 0.1% or more, more preferably 1% or more. However, when the content of these components is too large, the devitrification resistance tends to decrease, so it is preferably 25% or less, more preferably 20% or less, and still more preferably 10% or less.

The fluorine component is a component that improves chemical durability and devitrification resistance. However, when there is too much content, the refractive index will fall easily. The content of the fluorine component (in terms of F ₂ ) is preferably 0 to 20%, more preferably 0.1 to 15%, and still more preferably 1 to 10%. In addition, as a fluorine raw material, SnF ₂ , ZnF ₂ , AlF ₃ , MgF ₃ , SrF ₃ , CaF ₃ , or the like can be used.

In order to obtain glass having a desired refractive index and Abbe number, the content of SnO+SnF ₂ is preferably 45% or more, more preferably 55% or more. However, if the content is too large, the devitrification resistance is likely to decrease, so the content of SnO+ _SnF2 is preferably 80% or less, more preferably 70% or less, still more preferably 69% or less, particularly preferably 67.5% or less.

Fe ₂ O ₃ , NiO, and CoO are components that lower the transmittance. Therefore, the content of these components is preferably 0.1% or less.

Also, rare earth components such as Ce, Pr, Nd, Eu, Tb, and Er may lower the transmittance, so the contents of these components are preferably 0.1% or less in terms of oxides.

In addition, In, Ga, and Ge may lower the transmittance, and since they are expensive, their contents are preferably small. Specifically, the content of these components is preferably 0.1% or less, more preferably not contained, in terms of oxides.

For environmental reasons, the optical glass according to the first aspect of the present invention does not substantially contain (specifically, less than 0.1%) lead components (eg, PbO) and arsenic components (eg, As ₂ O ₃ ).

The optical glass according to the first aspect of the present invention has a refractive index (nd) of preferably 1.6 or more, more preferably 1.65 or more, still more preferably 1.7 or more, particularly preferably 1.72 or more. The upper limit is not particularly limited, but since the glass tends to become unstable when the refractive index is too high, it is preferably 1.95 or less, more preferably 1.9 or less.

The Abbe number (νd) of the optical glass according to the first aspect of the present invention is preferably 40 or less, more preferably 35 or less, still more preferably 30 or less, particularly preferably 28 or less, most preferably 25 or less. When the Abbe number is too low, the glass tends to become unstable, so it is preferably 15 or more, and more preferably 16 or more.

Satisfying these optical characteristics reduces chromatic dispersion, so it is suitable as an optical lens for high-performance and compact optical devices.

In addition, in the optical glass according to the first aspect of the present invention, the Abbe number (νd) and the partial dispersion ratio (θg, F) preferably satisfy the relationship of (θg, F)≤-0.0047×νd+0.76. When this relationship is satisfied by the Abbe number and the partial dispersion ratio, optical characteristics of high dispersion and low partial dispersion ratio can be easily achieved.

The optical glass according to the first aspect of the present invention preferably has a coloring degree λ ₇₀ of less than 500 nm, more preferably 470 nm or less, still more preferably 460 nm or less. When the degree of coloring _λ70 is too large, the transmittance in the visible region or the near-ultraviolet region tends to be poor, and it tends to be difficult to use for various optical lenses and the like.

The optical glass according to the first aspect of the present invention has a yield point of preferably 500°C or lower, more preferably 450°C or lower, still more preferably 425°C or lower, particularly preferably 420°C or lower. When the yield point is too high, compression molding at low temperature becomes difficult, and problems such as mold contamination due to oxidation of the mold and volatilization of glass components tend to occur, and problems such as fusion of glass and the mold tend to occur.

In the optical glass according to the first aspect of the present invention, the water resistance according to JOGIS is preferably grade 2 or higher. If the water resistance is within this range, surface deterioration is unlikely to occur due to washing after polishing or use under high temperature and high humidity.

The optical glass according to the first aspect of the present invention preferably has a coefficient of thermal expansion at 30 to 200°C of 100×10 ^-7 to 200×10 ^-7 /°C, more preferably 120×10 ^-7 to 180×10 ^-7 /°C . When the coefficient of thermal expansion is too small, the releasability of the glass from the press-molding mold tends to decrease during press-molding. On the other hand, when the coefficient of thermal expansion is too large, the glass is easily broken during press molding.

The optical glass according to the first aspect of the present invention preferably has a Young's modulus of 15 to 50 GPa, more preferably 20 to 40 GPa. When the Young's modulus is too low, the mechanical strength decreases, and it becomes easy to break during handling. On the other hand, when the Young's modulus is too high, the releasability of the glass from the press-molding mold tends to decrease during press-molding.

Next, a method for producing the optical glass according to the first aspect of the present invention and a method for producing optical elements such as phototube lenses and imaging lenses using the optical glass according to the first aspect of the present invention will be described.

First, raw materials are blended so as to have a desired composition, and then melted in a melting furnace. Here, adjustment of the refractive index and homogenization of the composition can be achieved by producing cullet by primary melting and performing secondary melting using the cullet. By homogenizing the composition, glass with high transmittance can be obtained. In addition, during secondary melting, fine control of the refractive index can be performed by using cullet with a high refractive index and cullet with a low refractive index. The melting atmosphere is particularly preferably an inert atmosphere or a reducing atmosphere. For example, homogeneous glass can be easily obtained by melting in an inert atmosphere such as nitrogen or argon. Metals such as platinum and gold, refractory materials, quartz glass, glassy carbon, and the like can be used as the vessel for glass melting. In particular, a gold container is preferable since an alloy reaction with SnO hardly occurs. In addition, as a metal container, it is preferable to use a reinforcing material in which oxides such as ZrO are dispersed.

Next, the molten glass is dropped from the tip of the nozzle and cooled while being shaped (droplet forming), whereby a preform glass composed of the optical glass according to the first aspect of the present invention is obtained. Alternatively, the molten glass is quenched and cast, and a glass block is made at one time, which is ground, ground, and cleaned to obtain prefabricated glass.

As the material of the nozzle used for droplet formation, the same material as that of the container for glass melting can be used. In addition, when the wettability of the glass to the nozzle is high, molding streaks are likely to occur. The nozzle made of gold is preferable because the wettability of glass is low and the occurrence of molding streaks can be suppressed.

Next, precast glass is put into the precision-processed mold, heated to a softened state, and press-molded to transfer the surface shape of the mold to the precast glass (compression molding). In order to suppress oxidation of the mold, the atmosphere during press molding is preferably an inert atmosphere such as a nitrogen atmosphere. In this manner, optical elements such as photopickup tube lenses and photography lenses can be obtained.

<The second aspect of the present invention>

The optical glass according to the second aspect of the present invention is characterized by containing 23.5 to 85% of SnO, 0.1 to 49.9% of P ₂ O ₅ , 0 to 2% of ZrO ₂ , and 0.1 to 20% of La in mole percent. ₂ O ₃ +Gd ₂ O ₃ +Ta ₂ O ₅ +WO ₃ +Nb ₂ O ₅ +TiO ₂ +Y ₂ O ₃ +Yb ₂ O ₃ +GeO ₂ and 0~1% MgO+CaO+SrO+BaO , and substantially free of lead and arsenic. Hereinafter, the reason for specifying each component content as mentioned above is demonstrated. In addition, "%" means "mol%" in the following description about content of each component, unless otherwise specified.

SnO is an essential component for achieving high refractive index and highly dispersed optical properties and improving chemical durability, and also has an effect of reducing the partial dispersion ratio. The content of SnO is 23.5-85%, preferably 27.5-82.5%, more preferably 30-80%, still more preferably 32.5-77.5%, particularly preferably 35-75%. When the content of SnO is too small, it is difficult to achieve high refractive index characteristics, and there is also a tendency for weather resistance and chemical durability to decrease. On the other hand, when there is too much content of SnO, vitrification becomes difficult, or devitrification resistance falls easily. In addition, in the second aspect of the present invention, the SnO component content refers to the content of Sn components other than SnO (metal Sn, SnO ₂ , etc.) also calculated in terms of SnO.

P ₂ O ₅ is a constituent of the glass skeleton. In addition, it has an effect of improving light transmittance (especially light transmittance near the ultraviolet region). Especially in the case of glass with a high refractive index, the effect of improving the light transmittance by P ₂ O ₅ is easily obtained. In addition, it also has the effect of suppressing devitrification. The content of P ₂ O ₅ is 0.1 to 49.9%, preferably 1 to 45%, more preferably 5 to 40%, still more preferably 7.5 to 35%, particularly preferably 10 to 30%. When the content of P ₂ O ₅ is too small, it is difficult to obtain the above effects. On the other hand, when the content of P ₂ O ₅ is too high, the content of SnO becomes relatively small, and the refractive index tends to decrease. In addition, weather resistance tends to decrease.

ZrO ₂ is a component that improves weather resistance. However, when the content is too large, the devitrification resistance will fall, or the melting temperature will rise, and the light transmittance will tend to fall. Therefore, the content of ZrO ₂ is 0 to 2%, preferably 0 to 1.5%, more preferably 0.1 to 1%, and still more preferably 0.2 to 0.5%.

La ₂ O ₃ , Gd ₂ O ₃ , Ta ₂ O ₅ , WO ₃ , Nb ₂ O ₅ , TiO ₂ , Y ₂ O ₃ , Yb ₂ O ₃ and GeO ₂ are optical characteristic ingredients. In addition, it also has an effect of improving weather resistance. The content of La ₂ O ₃ +Gd ₂ O ₃ +Ta ₂ O ₅ +WO ₃ +Nb ₂ O ₅ +TiO ₂ +Y ₂ O ₃ +Yb ₂ O ₃ +GeO ₂ is 0.1 to 20%, preferably 0.3 to 15%, more preferably 0.5 to 10%, still more preferably 1 to 7.5%. When the content of these components is too small, it is difficult to achieve the above-mentioned effect, and on the other hand, when it is too large, disadvantages such as a decrease in devitrification resistance, an increase in melting temperature, and a decrease in light transmittance are likely to occur.

In addition, the effect and preferable content of each of the above-mentioned components are as follows.

La ₂ O ₃ and Gd ₂ O ₃ are components that hardly decrease the light transmittance and increase the refractive index. However, when the content is too large, it becomes difficult to obtain a highly dispersed glass while devitrification resistance falls. Therefore, the content of these components is preferably 0 to 20%, more preferably 0.1 to 15%, and still more preferably 1 to 10%.

Ta ₂ O ₅ , WO ₃ , and Nb ₂ O ₅ are components that hardly lower light transmittance, increase refractive index, and disperse. However, when there is too much content, devitrification resistance will fall easily. Therefore, the content of these components is preferably 0 to 15%, more preferably 0.1 to 10%, and still more preferably 1 to 5%.

TiO ₂ is a component that has the effect of increasing the refractive index and dispersion. Moreover, it has the effect of improving devitrification resistance. However, when the content is too large, the light transmittance tends to decrease. In particular, when Fe components are contained in glass as impurities in a large amount (for example, 20 ppm or more), the light transmittance tends to decrease significantly. Moreover, devitrification resistance falls easily. Therefore, the content of TiO ₂ is preferably 0 to 20%, more preferably 0.1 to 15%, and still more preferably 1 to 10%.

Y ₂ O ₃ , Yb ₂ O ₃ , and GeO ₂ have effects of hardly lowering light transmittance, increasing refractive index, and dispersing. However, when there is too much content, devitrification resistance will fall easily. Therefore, the content of these components is preferably 0 to 20%, more preferably 0.1 to 20%, and still more preferably 1 to 10%.

MgO, CaO, SrO, and BaO (alkaline earth metal oxide) are components functioning as a flux. In addition, it has the effect of improving weather resistance, suppressing the elution of glass components into various cleaning solutions such as polishing water, or suppressing deterioration of the glass surface in a high-temperature and high-humidity state. However, when the content of these components is too large, the liquidus temperature rises (the liquidus viscosity falls), and devitrified substances tend to be easily precipitated in the melting or molding process. As a result, mass production becomes difficult. In addition, these components have a characteristic that they do not greatly vary the refractive index and Abbe's number. In view of the above, the content of MgO+CaO+SrO+BaO is 0 to 1%, preferably 0 to 0.9%, more preferably 0.1 to 0.7%, and still more preferably 0.2 to 0.5%.

In the second aspect of the present invention, in order to obtain glass having excellent devitrification resistance and high mechanical strength, it is preferable to adjust the content of SnO+P ₂ O ₅ . Specifically, the content of SnO+P ₂ O ₅ is preferably 30% or more, more preferably 40% or more, and still more preferably 50% or more. In addition, the upper limit is not particularly limited, but considering the content of other components, it is preferably 99.9% or less, more preferably 99.5% or less, and still more preferably 99% or less.

In the second aspect of the present invention, it is preferable to adjust (SnO+La ₂ O ₃ +Gd ₂ O ₃ +Ta ₂ O ₅ +WO ₃ +Nb ₂ O ₅ +TiO ₂ +Y ₂ O ₃ +Yb ₂ O ₃ +GeO ₂ )/P ₂ O ₅ ratio. Specifically, the ratio is preferably 1.2 or more, more preferably 1.5 or more, and still more preferably 1.75 or more. The upper limit is not particularly limited, but if it is too large, vitrification becomes difficult, so it is preferably 300 or less, more preferably 100 or less, still more preferably 10 or less, particularly preferably 5 or less.

In the second aspect of the present invention, it is preferable to adjust (SnO+La ₂ O ₃ +Gd ₂ O ₃ +Ta ₂ O ₅ +WO ₃ +Nb ₂ O ₅ +TiO ₂ +Y ₂ O ₃ +Yb ₂ O ₃ +GeO ₂ +MgO+CaO+SrO+BaO)/P ₂ O ₅ ratio. Specifically, the ratio is preferably 1.2 or more, more preferably 1.5 or more, and still more preferably 1.75 or more. When it is 1.2 or less, it becomes difficult to obtain glass with a high refractive index and excellent weather resistance, and glass with high mechanical properties. The upper limit is not particularly limited, but if it is too large, vitrification becomes difficult, so it is preferably 300 or less, more preferably 100 or less, still more preferably 10 or less, particularly preferably 5 or less.

The optical glass according to the second aspect of the present invention may contain the following components in addition to the above components.

ZnO is also a component that functions as a flux like alkaline earth oxides. In addition, it has the effect of improving weather resistance, suppressing the elution of glass components into various cleaning solutions such as polishing water, or suppressing deterioration of the glass surface in a high-temperature and high-humidity state. In addition, ZnO also has an effect of stabilizing vitrification. In view of the above, the content of ZnO is preferably 0 to 10%, more preferably 0.1 to 5%, and still more preferably 0.2 to 1%. When the content of ZnO is too high, the transmittance in the visible region or the near ultraviolet region tends to decrease, or it tends to devitrify. In addition, the partial dispersion ratio tends to increase.

Li ₂ O is a component that has the greatest effect of lowering the softening point among alkali metal oxides, and has a small increase in liquidus temperature. In addition, it has the effect of reducing the partial dispersion ratio. However, since Li ₂ O improves the phase-separation property of glass, if the content thereof is too large, the liquidus temperature may rise, devitrified substances may be easily precipitated, and workability may be lowered. In addition, Li ₂ O tends to lower the chemical durability and also tends to lower the light transmittance. Therefore, the content of Li ₂ O is preferably 0 to 10%, more preferably 0 to 8%, and still more preferably 0.1 to 5%.

Na ₂ O has the effect of lowering the softening point similarly to Li ₂ O. In addition, it has the effect of reducing the partial dispersion ratio. However, when the content is too large, the refractive index tends to be significantly lowered or the generation of streaks tends to be promoted. In addition, the liquidus temperature rises, and devitrified substances tend to precipitate, which may lower workability. Therefore, the content of Na ₂ O is preferably 0 to 10%, more preferably 0 to 8%, and still more preferably 0.1 to 5%.

K ₂ O also has the effect of lowering the softening point similarly to Li ₂ O. In addition, it also has the effect of reducing the partial dispersion ratio. However, when the content is too large, the refractive index tends to decrease significantly, or the weather resistance tends to decrease. In addition, the liquidus temperature rises, and devitrified substances are easily precipitated. Therefore, the content of K ₂ O is preferably 0 to 10%, more preferably 0 to 8%, and still more preferably 0.1 to 5%.

In addition, the content of Li ₂ O+Na ₂ O+K ₂ O is preferably 0 to 10%, more preferably 0 to 8%. When the content of Li ₂ O+Na ₂ O+K ₂ O is too large, devitrification tends to occur and the chemical durability also tends to decrease. In addition, it is difficult to obtain desired optical characteristics. There is also a tendency for the light transmittance to decrease.

B ₂ O ₃ and SiO ₂ are components of the glass skeleton. In addition, these components have an effect of increasing the light transmittance, and especially have a high effect of suppressing a decrease in the light transmittance near the ultraviolet region. Especially in the case of glass with a high refractive index, the effect of improving the light transmittance by these components is easily obtained. In addition, it also has the effect of improving devitrification resistance and chemical durability.

The content of B ₂ O ₃ is preferably 0 to 20%, more preferably 0.1 to 15%. When there is too much content _of B2O3, a refractive index will _fall easily. In addition, weather resistance and chemical durability tend to decrease.

The content of SiO ₂ is preferably 0 to 20%, more preferably 0.1 to 15%. When there is too much content of _SiO2 , a refractive index will fall easily. In addition, streaks and bubbles due to undissolved glass remain in the glass, and there is a possibility that the quality required as glass for optical lenses and the like cannot be satisfied.

In the second aspect of the present invention, in order to obtain glass having high refractive index characteristics, B ₂ O ₃ +ZnO is preferably 20% or less, more preferably 10% or less. In addition, in order to obtain a glass having excellent devitrification resistance, weather resistance, and chemical durability, and excellent light transmittance in the visible region and the near ultraviolet region, it is preferable to set B ₂ O ₃ +ZnO to 0.1% or more, more preferably 1%. %above.

Al ₂ O ₃ is a component capable of forming a glass skeleton together with SiO ₂ or B ₂ O ₃ . In addition, it has the effect of improving weather resistance, especially the effect of suppressing the selective elution of components such as P ₂ O ₅ and alkali metal oxides in the glass into water is large. The content of Al ₂ O ₃ is preferably 0 to 10%, more preferably 0.1 to 5%. When the content of Al ₂ O ₃ is too large, it is easy to devitrify. In addition, the melting temperature becomes high, and streaks and bubbles due to undissolved tend to remain in the glass. As a result, there is a possibility that the quality required as glass for optical lenses and the like cannot be satisfied. In addition, there is a tendency for light transmittance to decrease.

TeO ₂ has the effects of hardly lowering the light transmittance, increasing the refractive index, and dispersing. In addition, it has the effect of reducing the partial dispersion ratio. However, when there is too much content, devitrification resistance will fall easily. Therefore, the content of TeO ₂ is preferably 0 to 15%, more preferably 0.1 to 10%, and still more preferably 1 to 5%.

As a clarifying agent, Cl, S or Br may be contained. The content of Cl+S+Br is preferably 0.01 to 1%, more preferably 0.05 to 0.5%. When the content of Cl+S+Br is too small, the effect as a clarifier tends to be insufficient. On the other hand, if the content of Cl+S+Br is too large, it will volatilize during melting and easily corrode the melting vessel and the like.

Fe ₂ O ₃ , NiO, and CoO are components that lower light transmittance. Therefore, the content of these components is preferably less than 0.1% each.

In addition, since rare earth components such as Ce, Pr, Nd, Eu, Tb, and Er may also lower the light transmittance, the contents of these components are preferably less than 0.1% in terms of oxides.

In addition, In and Ga may lower the light transmittance, and since they are expensive, they are preferably less than 0.1% in terms of oxides.

Moreover, the optical glass of the second aspect of the present invention does not substantially contain (specifically, less than 0.1%) lead components (eg, PbO) and arsenic components (eg, As ₂ O ₃ ) for environmental reasons.

The optical glass according to the second aspect of the present invention has a refractive index (nd) of preferably 1.6 or more, more preferably 1.65 or more, still more preferably 1.7 or more, particularly preferably 1.72 or more. The upper limit is not particularly limited, but since the glass tends to become unstable when the refractive index is too high, it is preferably 1.95 or less, more preferably 1.9 or less.

The Abbe number (νd) of the optical glass according to the second aspect of the present invention is preferably 40 or less, more preferably 35 or less, still more preferably 30 or less, particularly preferably 28 or less, most preferably 25 or less. In addition, the lower limit is not particularly limited, but when the Abbe number is too low, the glass tends to become unstable, so it is preferably 15 or more, and more preferably 16 or more.

In addition, in the optical glass according to the second aspect of the present invention, the Abbe number (νd) and the partial dispersion ratio (θg, F) preferably satisfy the relationship of (θg, F)≤-0.0047×(νd)+0.76. When this relationship is satisfied by the Abbe number and the partial dispersion ratio, optical characteristics of high dispersion and low partial dispersion ratio can be easily achieved.

In the optical glass according to the second aspect of the present invention, the degree of coloring λ ₇₀ is preferably less than 500 nm, more preferably 470 nm or less, still more preferably 460 nm or less. When the degree of coloring _λ70 is too large, the light transmittance in the visible region or the near-ultraviolet region tends to be poor, making it difficult to use it in various optical lenses and the like.

The optical glass according to the second aspect of the present invention has a yield point of preferably 500°C or lower, more preferably 450°C or lower, still more preferably 425°C or lower, particularly preferably 420°C or lower. When the yield point is too high, compression molding at low temperature becomes difficult, and problems such as mold contamination due to mold oxidation and volatilization of glass components tend to occur, and problems such as fusion of glass and mold tend to occur.

In the optical glass according to the second aspect of the present invention, the water resistance according to JOGIS is preferably grade 3 or higher, and the acid resistance is preferably grade 2 or higher. If the water resistance and acid resistance are in this range, it is difficult to cause surface deterioration due to washing after polishing or use under high temperature and high humidity.

Next, a method for producing the optical glass according to the second aspect of the present invention and a method for producing optical elements such as a phototube lens and a lens for photography using the optical glass according to the second aspect of the present invention will be described.

First, raw materials are blended so as to have a desired composition, and then melted in a melting furnace. In particular, the glass obtained by using stannous pyrophosphate (Sn ₂ P ₂ O ₇ ) as a raw material tends to be homogeneous. In addition, after the cullet is produced by primary melting, the cullet is used for secondary melting, whereby the adjustment of the refractive index and the homogenization of the composition can be achieved. By homogenizing the composition, glass with high light transmittance can be obtained. In addition, at the time of secondary melting, fine control of the refractive index can be performed by using cullet with a high refractive index and cullet with a low refractive index.

In addition, when metal Sn and metal Al used as reducing agents are used in combination with high refractive index components such as WO ₃ , Nb ₂ O ₅ , and TiO ₂ , the transmittance in the visible region or near ultraviolet region tends to decrease. Therefore, it is preferable not to contain metal Sn and metal Al in the raw material.

The melting atmosphere is preferably an inert atmosphere or a reducing atmosphere. For example, homogeneous glass can be easily obtained by melting in an inert atmosphere such as nitrogen or argon. Metals such as platinum and gold, refractory materials, quartz glass, glassy carbon, and the like can be used as the vessel for glass melting. Among metal containers, especially gold containers are preferable because the alloy reaction with SnO hardly occurs. In addition, as a metal container, it is preferable to use a reinforcing material in which an oxide such as ZrO ₂ is dispersed.

Next, the molten glass is dropped from the tip of the nozzle and cooled while being shaped (droplet forming), thereby obtaining a preform made of the optical glass according to the second aspect of the present invention. Alternatively, the molten glass is quenched and cast, and a glass block is made at one time, which is ground, ground, and cleaned to obtain prefabricated glass. Gold is preferably used as a nozzle material for droplet formation. When the glass of the second aspect of the present invention containing a large amount of SnO is droplet-formed using a metal nozzle, the glass tends to adhere to the periphery of the exit of the nozzle, and forming streaks are likely to occur due to the adhered glass. Since gold has low wettability with the glass of the second aspect of the present invention, the above-mentioned problems are less likely to occur.

Next, precast glass is put into a precision-processed mold, heated to a softened state, and press-molded to transfer the surface shape of the mold to the precast glass (compression molding). In order to suppress oxidation of the mold, the atmosphere during press molding is preferably an inert atmosphere such as a nitrogen atmosphere. In this manner, optical elements such as photopickup tube lenses and photography lenses can be obtained.

Example

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

Tables 1 to 3 show examples (No. 1 to 17, 21 to 23) and comparative examples (No. 18 to 20) of the first aspect of the present invention.

[Table 1]

[Table 2]

[table 3]

Each sample was prepared as follows.

First, raw materials were blended so as to have the respective compositions shown in the table, and melted at 700 to 1000° C. for 1 hour in a nitrogen atmosphere using a gold container. Molten glass was flowed out on a preheated metal plate, and after annealing, samples suitable for each measurement were prepared.

The obtained samples were measured for refractive index (nd), Abbe number (νd), partial dispersion ratio (θg, F), coefficient of thermal expansion, yield point (Tf), Young's modulus, and degree of coloration λ ₇₀ . In addition, vitrification, water resistance, acid resistance and weather resistance were evaluated. The results are shown in Tables 1-3.

The refractive index is represented by the measured value with respect to the d-line (587.6 nm) of a helium lamp.

The Abbe number uses the above-mentioned refractive index of the d line, the F line (486.1nm) and the value of the refractive index of the C line (656.3nm) of the hydrogen lamp, by the Abbe number (νd)=[(nd-1)/(nF -nC)] formula is calculated.

As far as the partial dispersion ratio is concerned, the refractive index nC of the C-line, the refractive index nF of the F-line and the refractive index ng of the g-line (wavelength 435.835nm) of the hydrogen lamp are measured, and the partial dispersion ratio (θg, F)=(ng- nF)/(nF-nC) formula calculation.

The yield point and thermal expansion coefficient were measured using a dilatometer. In addition, the thermal expansion coefficient adopts the value in the temperature range of 30-200 degreeC.

Young's modulus was measured at room temperature by the bending resonance method.

As far as the coloring degree _λ70 is concerned, the transmittance in the 200-800nm wavelength region is measured at intervals of 0.5nm using a spectrophotometer for an optically polished sample with a thickness of 10mm±0.1mm, and the 70% transmittance is represented by Shortest wavelength evaluation.

Regarding vitrification, each sample was observed with an optical microscope, and the case where devitrification was not confirmed on the surface or inside was rated as "◯", and the case where devitrification was confirmed was rated as "×".

Water resistance and acid resistance were measured based on the powder method prescribed by JOGIS.

In terms of weather resistance, after exposing each sample for 500 hours under the conditions of a temperature of 85°C and a humidity of 85% using a high-temperature and high-humidity tester, it was evaluated as "○" when there was no change in appearance, and a slight change in gloss was seen. The cases where the gloss was significantly lost or the cracks were formed were evaluated as "X".

The samples of Example Nos. 1 to 17 and 21 to 23 had desired optical properties, yield points, and degree of coloration λ ₇₀ , and were also excellent in water resistance, acid resistance, and weather resistance. On the other hand, the sample of Comparative Example No. 18 was not vitrified, and the sample of No. 19 had a low refractive index of 1.5640 and was inferior in weather resistance. The sample No. 20 had a low refractive index of 1.5826, and was inferior in characteristics of water resistance, acid resistance, and weather resistance.

Tables 4 to 6 show Examples (No. 31 to 54) and Comparative Examples (No. 55, 56) of the second aspect of the present invention.

[Table 4]

[table 5]

[Table 6]

Each sample was prepared as follows.

First, raw materials were blended so as to have the respective compositions shown in the table, and melted at 700 to 1000° C. for 1 hour in a nitrogen atmosphere using a gold container. The obtained molten glass was flowed out on a preheated metal plate, and after annealing, a sample suitable for each measurement was produced.

The obtained samples were measured for refractive index (nd), Abbe number (νd), partial dispersion ratio (θg, F), yield point (Tf), and degree of coloration λ ₇₀ . In addition, vitrification, water resistance, acid resistance, and weather resistance were evaluated. The results are shown in Tables 1-3.

The refractive index is represented by the measured value with respect to the d-line (587.6 nm) of a helium lamp.

The Abbe number uses the above-mentioned refractive index of the d-line, the values of the refractive index of the F-line (486.1nm) and the C-line (656.3nm) of the hydrogen lamp, and is determined by the Abbe number (νd)=(nd-1)/(nF- nC) formula is calculated.

As far as the partial dispersion ratio is concerned, the refractive index nC of the C-line, the refractive index nF of the F-line and the refractive index ng of the g-line (wavelength 435.835nm) of the hydrogen lamp are measured, and the partial dispersion ratio (θg, F)=(ng- nF)/(nF-nC) formula calculation.

The yield point was measured using a dilatometer.

In terms of coloring degree λ ₇₀ , for optically polished samples with a thickness of 10 mm ± 0.1 mm, use a spectrophotometer to measure the light transmittance in the wavelength region of 200 to 800 nm at intervals of 0.5 nm, which means 70% light transmittance The shortest wavelength evaluation of the rate.

In terms of vitrification, each sample was observed with an optical microscope (×10), and the case where devitrification was not confirmed on the surface and inside was evaluated as "○", and the case where devitrification was confirmed on the surface or inside was evaluated as " ×".

Water resistance and acid resistance were measured based on the powder method prescribed by JOGIS.

In terms of weather resistance, after exposing each sample for 500 hours under the conditions of a temperature of 85°C and a humidity of 85% using a high-temperature and high-humidity tester, it was evaluated as "○" when there was no change in appearance, and a slight change in gloss was seen. The cases where the gloss was significantly lost or the cracks were formed were evaluated as "X".

The samples of Example Nos. 31 to 54 had desired optical properties, yield points, and degree of coloration λ ₇₀ , and were also excellent in water resistance, acid resistance, and weather resistance. On the other hand, the sample of Comparative Example No. 55 had a low refractive index of 1.5640 and a high Abbe number of 52.5, and was inferior in water resistance and weather resistance. The sample No. 56 was poor in water resistance and weather resistance.

production availability

The optical glass of the present invention is good as a glass material for compression molding used in optical pickup tube lenses for CD, MD, DVD, and other various optical disk systems, video cameras, and general camera photography lenses. In addition, it can also be used for glass materials for optical communication and the like produced by molding methods other than press molding. In addition, by compounding the optical glass of the present invention and phosphor powder, it can also be used as a wavelength conversion member for changing the wavelength of ultraviolet light and visible light.

Claims (25)

1. an opticglass, is characterized in that:

In mol%, containing the SnO of 43.5 ~ the 80% and P of 0.1 ~ 29.9% ₂o ₅+ B ₂o ₃+ SiO ₂, and in fact not containing lead composition and arsenic composition.

2. opticglass as claimed in claim 1, is characterized in that:

P ₂o ₅content be 0.1 ~ 29.5%.

3. opticglass as claimed in claim 1 or 2, is characterized in that:

In mol%, SnO/ (P ₂o ₅+ B ₂o ₃+ SiO ₂) be more than 1.5.

4. the opticglass according to any one of claims 1 to 3, is characterized in that:

In mol%, the CaO+SrO+BaO+MgO+ZnO of 0 ~ 25% is also contained.

5. the opticglass according to any one of Claims 1 to 4, is characterized in that:

In mol%, the Al of 0 ~ 10% is also contained ₂o ₃+ ZrO ₂.

6. the opticglass according to any one of Claims 1 to 5, is characterized in that:

Yield-point is less than 500 DEG C.

7. the opticglass according to any one of claim 1 ~ 6, is characterized in that:

Water tolerance based on JOGIS is more than 2 grades.

8. the opticglass according to any one of claim 1 ~ 7, is characterized in that:

Specific refractory power is more than 1.6, and Abbe number is less than 40.

9. the opticglass according to any one of claim 1 ~ 8, is characterized in that:

Abbe number (ν d) and partial dispersion ratio (θ g, F) meet the relation of (θ g, F)≤-0.0047 × (ν d)+0.76.

10. the opticglass according to any one of claim 1 ~ 9, is characterized in that:

Degree of staining λ ₇₀be less than 500nm.

11. opticglass according to any one of claim 1 ~ 10, is characterized in that:

It is for optical lens.

12. opticglass according to any one of claim 1 ~ 11, is characterized in that:

It is for compression molding.

13. 1 kinds of optical elements, is characterized in that:

Employ the opticglass according to any one of claim 1 ~ 12.

14. 1 kinds of opticglass, is characterized in that:

In mol%, containing the SnO of 23.5 ~ 85%, the P of 0.1 ~ 49.9% ₂o ₅, 0 ~ 2% ZrO ₂, 0.1 ~ 20% La ₂o ₃+ Gd ₂o ₃+ Ta ₂o ₅+ WO ₃+ Nb ₂o ₅+ TiO ₂+ Y ₂o ₃+ Yb ₂o ₃+ GeO ₂with 0 ~ 1% MgO+CaO+SrO+BaO, and in fact not containing lead composition and arsenic composition.

15. opticglass as claimed in claim 14, is characterized in that:

In mol%, containing 0 ~ 10% Li ₂o+Na ₂o+K ₂o.

16. opticglass as described in claims 14 or 15, is characterized in that:

In mol%, containing 0 ~ 10% B ₂o ₃+ ZnO.

17. opticglass according to any one of claim 14 ~ 16, is characterized in that:

In mol%, containing 0.01 ~ 1% Cl+S+Br.

18. opticglass according to any one of claim 14 ~ 17, is characterized in that:

Yield-point is less than 500 DEG C.

19. opticglass according to any one of claim 14 ~ 18, is characterized in that:

Water tolerance based on JOGIS is more than 3 grades.

20. opticglass according to any one of claim 14 ~ 19, is characterized in that:

Specific refractory power is more than 1.6, and Abbe number is less than 40.

21. opticglass according to any one of claim 14 ~ 20, is characterized in that:

Abbe number (ν d) and partial dispersion ratio (θ g, F) meet the relation of (θ g, F)≤-0.0047 × (ν d)+0.76.

22. opticglass according to any one of claim 14 ~ 21, is characterized in that:

Degree of staining λ ₇₀be less than 500nm.

23. opticglass according to any one of claim 14 ~ 22, is characterized in that:

It is for optical lens.

24. opticglass according to any one of claim 14 ~ 23, is characterized in that:

It is for compression molding.

25. 1 kinds of optical elements, is characterized in that:

Employ the opticglass according to any one of claim 14 ~ 24.