WO2008050819A1 - Optical glass - Google Patents

Abstract

Provided is an optical glass, which has a refractive index (nd) of 1.9 or more, an Abbe's number (νd) of 15 or more, a glass transition point (Tg) of 300°C or below, does not contain Pb and/or As compound and contains a TeO2 component of 50 mol% or more. The optical glass contains an R2O compound (R is one or more kinds of elements selected from among a group composed of Li, Na, K and Cs), ZnO component and Bi2O3 component, and furthermore, contains Al2O3 and/or Ga2O3 component.

Description

 TECHNICAL FIELD The present invention relates to an optical glass that is a high refractive index optical glass, has a very low glass transition point (T g), is excellent in chemical durability, and is suitable for precision press molding. BACKGROUND ART Generally, lenses constituting an optical system include a spherical lens and an aspheric lens. Many spherical lenses are manufactured by grinding and polishing glass molded products obtained by reheat press molding glass materials. On the other hand, an aspherical lens is made by press-molding a heat-softened lens preform with a mold having a high-precision molding surface, and transferring the shape of the high-precision molding surface of the mold to the lens preform. The main method is to obtain it, that is, to be manufactured by precision press molding.

 In order to obtain a glass molded product such as an aspheric lens by precision press molding, it is necessary to perform press molding in a high temperature environment. Therefore, the mold used at this time is also exposed to high temperatures, and the mold is expensive. Press pressure is applied. Therefore, when the lens preform material is heat-softened and when the lens preform material is press-molded, the molding surface of the mold is oxidized or eroded, or the release film provided on the surface of the mold molding surface is damaged. As a result, it is often impossible to maintain a high-precision molding surface of the mold, and the mold itself is easily damaged. If this happens, the mold must be replaced, and the number of mold replacements will increase, making it impossible to achieve low cost and mass production. Therefore, the glass used as the lens preform material for precision press molding suppresses the above-mentioned damage, maintains a high-precision molding surface of the mold for a long time, and enables precision press molding at a low press pressure. Therefore, it is desired to have a glass transition point (T g) as low as possible.

 By the way, when performing precision press molding, the glass used as the lens preform material needs to have a mirror surface or a state close to it. The lens preform material is generally produced by a method that uses a dropping method to produce directly from molten glass or a method that uses grinding and polishing. However, considering the number of processes, the former method is more suitable. Commonly used. The lens preform material obtained by the dropping method is called a gob or glass gob. These lens preform materials need to be cleaned to remove dust and dirt on the surface before precision press molding. In addition, since it is exposed to high humidity even after it is molded as a lens, it requires a certain chemical durability.

 As one of glasses having a high refractive index and a low glass transition point (T g), tellurite-based glasses containing TeO 2 as a main component are known.

For example, Japanese Patent Application Laid-Open No. Sho 6 2-1 0 8 7 4 1 states that Te 0 ₂ — P b O— B ₂ 0 ₃ JP 2006-182577 B ₂ 0 ₃ — Te 0 ₂ — Z ηθ— La. O _s — Nb. ○ Series glass is listed. DISCLOSURE OF THE INVENTION The optical glass described in JP-A-62-108741 realizes a desired high refractive index dispersion, but contains a PbO component, which is not preferable from the viewpoint of environmental influences. Further, JP 2006- 182577 optical glass according to the order containing a large amount of L a ₂ 〇 ₃ and Nb ₂ 0 ₅ component disadvantage that shaking is not sufficiently low glass transition point (T g) obtained was there.

 In general, optical glass for precision press molding generally has poor chemical durability as a trade-off for reducing the glass transition point. Depending on the environment, the surface of the lens preform material In some cases, it was impossible to maintain a mirror surface or a state close to the mirror surface.

 The present invention comprehensively eliminates the disadvantages found in the above-described high refractive index optical glass, and also maintains excellent chemical durability while maintaining a high refractive index and a low glass transition point (Tg). We provide optical glass suitable for precision press molding.

The present inventors, in order to solve the above problems, the results of extensive research, the high refractive index optical glass as a main component T e O ₂ component can be realized the desired optical properties and chemical durability I found. Furthermore, a predetermined amount of R ₂ O component (R is one or more selected from the group consisting of Li, Na, K, C s), Z ηθ component, and B i ₂ 0 ₃ component, and A 1 ₂ the 0 ₃ and Ga ₂ 0 ₃ to one or both of the components is contained a predetermined amount, the refractive index while maintaining low glass transition point (T g), it combines the excellent chemical durability, the precision press molding We have found that suitable optical glass can be produced.

That is, in the first configuration of the present invention, the refractive index (nd) is 1.9 or more, the optical Abbe number (V d) is 15 or more, and the glass transition point (T g) is 300 ° C. or less. , free of P b and Z or a s compound is an optical glass characterized that you containing T E_〇 ₂ component 5 Omo 1% or more.

The second configuration of the present invention includes R ₂ O (R is one or more selected from the group consisting of Li, Na, K, and C s) component, Ζ η Ο component, and Bi ₂ 0 ₃ component. Contain and further A 1

The optical glass of the above constitution 1 containing ₂ 0 ₃ and Z or Ga ₂ 0 ₃ component. The third configuration of the present invention is mo 1% of oxide basis,

TeO ₂ 50-90%,

R ₂ O (R is L i, Na, K, 1 or more selected from the group consisting of C s). 5 to

30%,

 Z n O 1-30%

B i 2 0 ₃ 1-20%

The optical glass having the constitutions 1 and 2 containing

The fourth configuration of the present invention is characterized in that it contains 0.001 to 3. Omo 1% of Al ₂ 0 ₃ and / or G a ₂ 0 ₃ components in an outer ratio. Optical glass. A fifth constitution of the present invention is the optical glass according to any one of the constitutions 1 to 4, wherein the water resistance of the powder method is first grade, second grade or third grade.

A sixth configuration of the present invention is the optical glass according to any one of the above configurations 1 to 5, wherein the total content of B ₂ 0 ₃ , G 0 ₂ and P ₂ 0 ₅ components is 5 mol 1% or less.

Seventh configuration of the present invention, the optical glass of the R ₂ 0 is 1 ^ 1 ₂ O and Z or Na ₂ O component consisting previous Symbol Configuration 2-6.

 An eighth configuration of the present invention is the optical glass according to any one of the above configurations 1 to 7, which does not substantially contain an F component.

 The ninth configuration of the present invention is:

As an optional component at 1% mo based on oxide

S i 0 ₂ 0 to 10% and / or

 L i 2 O 0-30% and / or

 N a 2 O 0 -20% and / or

K ₂ O 0 ~ 15% and / / or

 C S 2 O 0-10% and Z or

 M g O o ~ 10% and Z or

 C a O 0-20% and Z or

 B a O 0-20% and / or

 SrO 0-20% and Z or

T io ₂ 0-10% and / or

Nb ₂ 0 ₅ 0-10% and / or

_{T a 2 O 5 0~ 1 0} % and / or

wo ₃ 0-10% and no or

 Z r O 2 o to 10% Z or

2 o ₃ 0-10% and or

Yb ₂ 0 ₃ 0 to 10% and / or

 La2O3 0-10% and / or

 G d 2 O 3 o to 10% and Z or

S b ₂ 0 ₃ 0 to 0.5%

It is the optical glass of the said structures 1-8 containing each component of these.

Tenth aspect of the present _{invention, Y 2 0 3, Yb 2} 0 3, L a 2 0 3 and G d ₂ O ₃ component optical total content of the structure 1-9 is less than 1% 10Mo of Glass.

 The eleventh configuration of the present invention is an optical element formed by precision press molding the optical glass of the above configurations 1 to 10.

 A twelfth configuration of the present invention is a precision press-molding preform made of the optical glass having the above configurations 1 to 10.

 The thirteenth configuration of the present invention is an optical element formed by precision press-molding the preform of configuration 12. .

According to the configuration of the present invention, an optical glass that is a high refractive index optical glass, has a very low glass transition point (Tg), is excellent in chemical durability, and is suitable for precision press molding. Can be provided. BEST MODE FOR CARRYING OUT THE INVENTION

Each component of the optical glass of the present invention will be described. Hereinafter, unless otherwise specified, the content of each component means _mo 1% based on oxide. “Oxide standard” means that the oxide, composite salt, metal fluoride, etc. used as a raw material of the glass component of the present invention are all decomposed and transformed into oxide when melted. It is a composition that describes each component contained in the glass, with the total mass of 100% being 100% by mass.

T e 0 ₂ component is a component having an effect of glass forming, in the present invention contains mandatory. However, if the amount is too small, it becomes difficult to vitrify, and if it is contained excessively, it tends to be unstable as glass. Therefore, in the present invention, the lower limit is preferably 50%, more preferably 55%, most preferably 60%, preferably 90%, more preferably 85%, and most preferably 80%. Is the upper limit.

The R ₂ O component (R is one or more selected from the group consisting of Li, Na, K, and C s) facilitates vitrification of the Te 0 ₂ component and reduces the glass transition point (T g). It is a component that has the effect of keeping it low, and is a useful component in the present invention. However, if the amount is too small, it tends to be insufficient for forming glass, and if it is contained excessively, the refractive index tends to decrease and devitrification tends to increase. Therefore, in the present invention, the total content of R ₂ O component is preferably 5%, more preferably 7%, most preferably 10% as the lower limit, preferably 30%, more preferably 27%, most Preferably, the upper limit is 25%.

Next, each component of R ₂ O will be described.

L i ₂ O component facilitates the vitrification of T e 0 ₂ component is a component having an effect of keeping the glass transition point (T g) lower. However, if contained excessively, the refractive index tends to decrease and devitrification tends to increase. The Li ₂ O component content in the present invention is preferably 1.0%, more preferably 3.0%, most preferably 5.0% as the lower limit, preferably 30%, more preferably 27%, Most preferably, the upper limit is 25%.

The N a ₂ O component is a component that facilitates vitrification of the Te 0 ₂ component and has the effect of keeping the glass transition point (T g) low. However, if contained excessively, the refractive index tends to decrease and devitrification tends to increase, so there is no problem even if it is not contained. The Na ₂ O component content in the present invention is preferably 20%, more preferably 17%, and most preferably 15%.

The K ₂ Ο component is a component that facilitates vitrification of the Te 0 ₂ component and has the effect of keeping the glass transition point (T g) low. However, if it is contained excessively, the refractive index tends to decrease and devitrification tends to increase, so there is no problem even if it is not contained. In the present invention, the K ₂ O component content is preferably 15%, more preferably 13%, and most preferably 10%.

The C s ₂ Ο component has an effect of facilitating vitrification of the Te 0 ₂ component. However, if contained excessively, the refractive index tends to decrease and devitrification tends to increase, so there is no problem even if it is not contained. In the present invention, C s _The upper limit of the ₂ O component is preferably 10.0%, more preferably 5.0%, and most preferably 3.0%.

Further, R ₂ O is preferably preferably made by one or both whichever L i ₂ O and Na ₂ O component. This other R ₂ O component is compared to L i ₂ O and Na ₂ O Ingredients, because the relatively easy devitrification deteriorates is not significant.

Z n O component is a component having an effect of facilitating the vitrification of T e 0 ₂ component is a useful component in the present invention. However, if the amount is too small, the glass tends to become unstable, and devitrification tends to increase even if it is contained excessively, and the disadvantage is that the refractive index is lowered and the glass transition point (Tg) tends to be high. There is. Therefore, in the present invention, the lower limit is preferably 1%, more preferably 2%, and most preferably 3%, preferably 30%, more preferably 27%, and most preferably 25%.

The B i _{20 3} component has the effect of facilitating vitrification of the Te 0 ₂ component and increasing the refractive index, and is a useful component in the invention. However, if the amount is too small, the glass tends to become unstable. Even if it is contained excessively, devitrification will increase, and the glass transition point (T g) tends to be high. There is. Therefore, in the present invention, the lower limit is preferably 1 ° / ₀ , more preferably 2%, most preferably 3%, preferably 20%, more preferably 17%, and most preferably 15%.

A 1 ₂ 0 ₃ and Ga ₂ 0 ₃ component is a component that both the effect of suppressing the devitrification of the glass, it preferably contains either one or both. However, if the amount is too small, the effect of suppressing devitrification tends to be insufficient, and even if contained excessively, devitrification tends to increase. Further, the refractive index decreases and the glass transition point (Tg) increases. There is a disadvantage that it is easy to invite. Therefore, in the present invention, the total content of the A 1 ₂ 0 ₃ and Ga ₂ 0 ₃ components is preferably 0.01%, more preferably 0.05%, and most preferably 0.1% as the lower limit. Preferably, the upper limit is 3.0%, more preferably 2.0%, and most preferably 1.0%.

Note that "outer percentage" during Honma specification, in the case where the total content of the oxide components other than A l ₂ 0 ₃ and G a ₂ 0 ₃ component assuming 100%, A l ₂ 0 ₃ and G a ₂ 0 ₃ means the relative mass% of the component.

For each component, A 1 ₂ 0 ₃ component is preferably 2.0%, more preferably 1. 5%, and most preferably a maximum of 0% 1.. G a ₂ 0 ₃ is preferably 2. 0%, more preferably 1. 5%, and most preferably a maximum of 0% 1.. Meanwhile, T e 0 ₂ component is can act as a glass forming oxide in the optical glass of the present invention, it is very difficult to vitrify alone. Therefore, the content of the component above mentioned (i.e. R ₂ 0, Z n O, and B i ₂ 0 ₃ component, and A 1 ₂ 0 ₃ Oyo one or both of the beauty Ga ₂ 0 ₃ component) low with one or more It is preferable to let them. Further, by containing a T e 0 ₂ component and the components at the same time, better stability, solubility, chemical durability, easily obtain a glass having a performance as an optical glass.

B ₂ 0 ₃ , Ge 0 ₂ and P ₂ 0 ₅ components are components that lower the refractive index and increase the glass transition point (T g), so the total amount is preferably 5.0%, more preferably Or 3.0%, and most preferably 1.0%. However, it does not matter if none is contained.

The upper limit of each component of B ₂ 0 ₃ , Ge 0 ₂ and P ₂ 0 ₅ is preferably 5.0%, more preferably 3.0%, and most preferably 1.0%.

The F component is a component that facilitates increasing devitrification, so it is preferably 5%, more preferably 2%, and most preferably not contained. The content of F in the present invention is such that the total amount of F in which a part or all of the oxides constituting the glass of the present invention are substituted with fluoride is based on 100% by mass of the oxide reference composition. Mass when calculated as F atoms. This is represented by / ₀ .

Since the S i 0 ₂ component is a component having an effect of improving devitrification, it can be optionally contained in the present invention. However, if contained in excess, devitrification tends to increase, and the refractive index tends to decrease, and the glass transition point (Tg) tends to increase. Therefore, in the present invention, the upper limit is preferably 10.0%, more preferably 5.0%, and most preferably 2.0%.

 Since the Mg 2 O component has an effect of improving devitrification, it can be optionally contained in the present invention. However, if contained in excess, devitrification tends to increase, and the refractive index tends to decrease, and the glass transition point (Tg) tends to increase. Therefore, in the present invention, the upper limit is preferably 10.0%, more preferably 5.0%, and most preferably 2.0%.

 Since the C a O component is a component having an effect of improving devitrification, it can be optionally contained in the present invention. However, if contained in excess, devitrification tends to increase, and the refractive index tends to decrease, and the glass transition point (Tg) tends to increase. Therefore, in the present invention, the upper limit is preferably 20. 0%, more preferably 7.0%, and most preferably 5.0%.

 Since the B a O component is a component having an effect of improving devitrification, it can be optionally contained in the present invention. However, if contained in excess, devitrification tends to increase, and the refractive index tends to decrease, and the glass transition point (Tg) tends to increase. Therefore, in the present invention, the upper limit is preferably 20.0%, more preferably 7.0%, and most preferably 5.0%.

 Since the SrO component is a component having an effect of improving devitrification, it can be optionally contained in the present invention. However, if contained in excess, devitrification tends to increase, and the refractive index tends to decrease, and the glass transition point (Tg) tends to increase. Therefore, in the present invention, the upper limit is preferably 20.0%, more preferably 7.0%, and most preferably 5.0%.

The T i 0 ₂ component is a component that has the effect of increasing the refractive index, and therefore can be optionally contained in the present invention. However, if contained in excess, devitrification tends to increase and the glass transition point (Tg) tends to be high. Therefore, in the present invention, the upper limit is preferably 10.0%, more preferably 7.0%, and most preferably 5.0%.

Since the N b ₂ 0 ₅ component is a component that has the effect of increasing the refractive index, it can be optionally contained in the present invention. However, if contained in excess, devitrification tends to increase, and there is a disadvantage that the glass transition point (Tg) tends to be high. Therefore, the present invention The upper limit is preferably 10.0%, more preferably 7.0%, and most preferably 5.0%.

Since T a ₂ 0 ₅ component is a component having an effect of increasing the refractive index can be arbitrarily containing the Te present invention smell. However, if contained in excess, devitrification tends to increase, and there is a disadvantage that the glass transition point (Tg) tends to be high. Therefore, in the present invention, the upper limit is preferably 10.0%, more preferably 7.0%, and most preferably 5.0%.

Since the wo ₃ component is a component that has the effect of increasing the refractive index, it can be optionally contained in the present invention. However, if it is contained excessively, devitrification tends to increase and the glass transition point (Tg) tends to be high. Therefore, in the present invention, the upper limit is preferably 10.0%, more preferably 7.0%, and most preferably 5.0%.

Z r 0 ₂ component can optionally contain In its contact with the present invention since a component having an effect of improving chemical durability. However, if it is contained excessively, devitrification tends to increase, and there is a disadvantage that the glass transition point (Tg) tends to be high. Therefore, in the present invention, the upper limit is preferably 10 · 0%, more preferably 5.0%, and most preferably 2.0%.

Υ ₂ ο ₃ components are effective in improving chemical durability, and therefore can be optionally contained in the present invention. However, if it is contained excessively, devitrification tends to increase, and there is a disadvantage that the glass transition point (Tg) tends to be high. Therefore, in the present invention, the total amount is preferably 10.0%, more preferably 7.0%.

Most preferably, the upper limit is 5.0%.

The Y b ₂ 0 ₃ component is a component that has the effect of increasing the refractive index, and therefore can be optionally contained in the present invention. However, if contained in excess, devitrification tends to increase, and there is a disadvantage that the glass transition point (Tg) tends to be high. Therefore, in the present invention, the upper limit of the total amount is preferably 10.0%, more preferably 7.0%, and most preferably 5.0%.

The La ₂ O ₃ component is a component that has the effect of increasing the refractive index, and therefore can be optionally contained in the present invention. However, if contained in excess, devitrification tends to increase, and there is a disadvantage that the glass transition point (Tg) tends to be high. Therefore, in the present invention, the upper limit of the total amount is preferably 10.0%, more preferably 7.0%, and most preferably 5.0%.

Since gd ₂ 0 ₃ component is a component having an effect of increasing the refractive index can be arbitrarily containing the Te present invention smell. However, if contained in excess, devitrification tends to increase, and there is a disadvantage that the glass transition point (Tg) tends to be high. Therefore, in the present invention, the total amount is preferably 10.0%, more preferably 7.0%, and most preferably 5.0%.

_{Y 2 0 3, Yb 2 0} 3, L a 2 0 3 and rare earth oxide consists of G d ₂ 0 ₃ component, any component having an effect of increasing the improvement and refractive index of the chemical durability as described above It is. However, if these components are contained excessively, devitrification tends to increase and the glass transition point (Tg) tends to increase. Therefore, in the present invention, the total amount is preferably 10.0%, more preferably 7.0%, most preferably Preferably, the upper limit is 5.0%.

Since S b ₂ 0 ₃ component is a component having an effect of refining action can be contained in arbitrary in the present invention. However, if contained in excess, devitrification tends to increase, and there is a disadvantage that the glass transition point (Tg) tends to be high. Therefore, in the present invention, the upper limit is preferably 0.5%, more preferably 0.4%, and most preferably 0.3%.

 Next, components that should not be contained in the optical glass of the present invention will be described. Lead compounds are not only used in the production of glass and fusion-shaking components during precision press molding, but also in the production of glass, as well as in cold processing of glass such as polishing and disposal of glass. Since measures are necessary and there is a problem that it is a component with a large environmental load, it should not be contained in the optical glass of the present invention.

As s ₂ 0 ₃ , the force dome and trim components both have harmful effects on the environment and have a very large environmental load, so they should not be included in the optical glass of the present invention.

 Furthermore, in the optical glass of the present invention, coloring components such as V, Cr, Mn, Fe, Co, Ni, CuMo, Eu, Nd, Sm, Tb, Dy, Er, etc. Since it is easy to lower the transmittance, it is preferable that the transmittance is not substantially contained. Here, “substantially does not contain” means that it is not contained artificially unless it is mixed as an impurity.

The glass composition of the present invention is directly mass because its composition is expressed in mo 1%. Although not expressed in the description of / _0, the composition expressed by mass% of each component present in the glass composition satisfying various properties required in the present invention generally takes the following values as oxide reference compositions. .

T e 0 ₂ 40-90%,

R ₂ O (R is one or more selected from the group consisting of L i, N a, K, C s) 5〜

30%,

 Z n O 1-20%

_{B i 2 0 3 1~ 5 0} % and

A 1 ₂ Og and / or Ga 2 O 3 divided by 0.005 to 3. Omol% and β 2 O 3 ヽ Ge O 2 and P 2 0 ₅ 0 to 5%

sio ₂ 0-10% and / or

L i ₂ O 0.5 to 10% and Z or

 N a a O 0 to: L 0% and / or

K ₂ O 0~ 1 0% and / or

 MgO 0-5% and / or

 C a O 0-20% and / or

 B a O 0-20% and / or

 SrO 0-20% and / or

T io ₂ 0~ 5% and / or

Nb ₂ 0 ₅ 0-20% and / or

 T a a O 5 0-25% and / or

WO a 0-: L 5% and / or Z r 0 ₂ o to 5% and / or

Y ₂ o ₃ 0-15% and / or

Yb ₂ 0 ₃ 0-25% and Z or

 La2O3 0-20% and / or

G d ₂ O 3 0-10% and / or

S b ₂ 0 ₃ 0 to 2% Next, physical properties defined in the present invention will be described.

 In the optical glass of the present invention, it is desirable that the refractive index (11 d) is 1.9 or more and the Abbe number (V d) is 15 or more. By having such an optical constant, it is possible to meet market demands such as reducing the number of lenses in the camera.

 The glass transition point is measured by measuring the thermal expansion of the glass. The higher the glass transition point, the higher the molding temperature, that is, the shorter the mold life. The optical glass of the present invention is preferably applicable not only to conventional super steel molds but also to precision press molding using molds such as stainless steel, so that the glass transition point is preferably 300 ° C or less. More preferably 295 ° C or less, most preferably 290 ° C or less

 In the present invention, as an index of chemical durability, the water resistance of the powder method specified by the Japan Optical Glass Industry Association Standard; J ◦ GIS 06-1999 is used. If the chemical durability is too bad, it will be difficult to use as optical glass. In particular, considering the application of the optical glass of the present invention to a lens preform material, it is preferably grade 1 to 3. More preferably, it is grade 1 to 2, most preferably grade 1.

 As described above, the optical glass of the present invention can be used as a preform material for press molding, or the molten glass can be directly pressed. When used as a preform material, the production method and precision press molding method are not particularly limited, and known production methods and molding methods can be used. As a method for producing a preform material, for example, a glass gob molding method described in JP-A-8-319124 or an optical glass production method and production apparatus described in JP-A-8-73229 can be directly applied from molten glass. A remodeling material can be manufactured, and plate glass or rod glass may be cold processed. Example

Examples of the present invention will be described below, but the present invention is not limited to these examples.

The compositions of Examples (No .:! To No. 1 1) of the glasses of the present invention are shown together with the refractive index ( _n d), Abbe number (vd), and glass transition point (T g) results of these glasses. Shown in 1-3. In the table, the composition of each component shall be expressed as mo 1%.

0 0 0 OOZdfAlOd 6180S0 / 800Z OAV Table 2

 Example

 No. 6 No. 7 No. 8 No. 9 No. 10

Te0 ₂ 65. 0 65. 0 70. 0 70. 0 65. 0

Li ₂ 0 20. 0 15. 0 5. 0 5. 0 10. 0

ZnO 10. 0 10. 0 10. 0 10. 0 10. 0

Bi ₂ 0 ₃ 1. 0 5. 0 5. 0 5. 0 5. 0

A1 ₂ 0 ₃ 0. 2 0. 2 0. 2 0. 2 0. 2

Na ₂ 0 5. 0 10. 0 10. 0

K ₂ 0 10. 0

 BaO

W0 ₃ 4.0

n PT 100. 2 100. 2 100. 2 100. 2 100. 2

Nd 2. 012 2. 017 2. 042 2. 005 2. 001 v d 20. 2 19. 0 18. 3 18. 5 18. 9

Tg (° C) 271 255 265 261 250 Powder method Water resistance (Class) 1 1

Table 3

The optical glasses (N o .l to N o. 1 1) of the embodiments of the present invention shown in Tables 1 to 3 are made of ordinary optical glass raw materials such as oxides, hydroxides, carbonates and nitrates. Weigh so that the composition ratio of each Example shown in Table 1 to Table 3 is the ratio, mix, put into platinum or gold crucible, and depending on the meltability depending on the composition. It could be obtained by melting for 30 minutes to 5 hours at 0 ° C, clarification, stirring and homogenizing, and then pouring into a mold or the like and gradually cooling.

 The refractive index (n d) and Abbe number (v d) were measured for the optical glass obtained at a slow cooling rate of 25 ° CZ.

 The glass transition point (T g) was measured by the method described in Japan Optical Glass Industry Association Standard J O J I S 0 8 -200 (Measurement Method of Thermal Expansion of Optical Glass). However, a specimen with a length of 50 mm and a diameter of 4 mm was used as a specimen.

The value of the grade showing the water resistance of the powder method was determined as follows according to the Japan Optical Glass Industry Association Standard; J OG IS 0 6 — 1 9 9 9. The glass of the example (No. 1 to 11) was crushed to a particle size of 4 25 to 60 μm, the crushed glass sample was taken in a specific gravity gram, placed in a platinum basket, and the platinum basket was put into pure water. Place in a quartz glass round-bottom flask containing (pH 6.5-5. 5) and treat in a boiling water bath for 60 minutes. When the weight loss rate is less than 0.05%, it is class 1, the weight loss rate is less than 0.05 to less than 10%, and the weight loss rate is 0.1 0. The case where it is less than ˜0.25% is classified as grade 3, and the smaller the number of grades, the better the water resistance of the glass.

 As can be seen from Tables 1 to 3, all of the optical glasses (No .:! To 1 1) of the examples of the present invention have optical constants within the above range, (refractive index (nd) and Abbe number (V d ) And the glass transition point (T g) is in the range of 300 ° C or less, making it suitable for precision mold press molding at low temperatures, and because of its good water resistance to the powder method, chemical durability. It can be applied to lens preform materials for precision press molding.

 The optical glass of the present invention is a high refractive index optical glass, has a very low glass transition point (Tg), and is excellent in scientific durability. Therefore, it is a lens preform material for precision press molding. It is suitable to apply.

Claims

The scope of the claims 1. Refractive index (nd) is 1.9 or more, Abbe number (V d) is 15 or more, glass transition point (T g) is 300 ° C or less, P b and / or A free of s compound, optical glass characterized by containing a T e 0 ₂ component 5 Omo 1% or more. 2. R ₂ O (R is one or more selected from the group consisting of Li, Na, K :, C s) component, Zn O component, Bi ₂ O ₃ component, and A The optical glass according to claim 1, comprising 1 ₂ 0 ₃ and / or G a ₂ o ₃ component.  3. At 1% mo based on oxide,  TeO a 5 0-9 0%, R ₂ O (R is one or more selected from the group consisting of Li, Na, K, C s) 5〜 3 0%,  Z n O:! ~ 30% and B i ₂ 0 ₃ :! ~ 20% The optical glass of Claim 1 or 2 containing each component of these. 4. The optical glass according to any one of A 1 2 0 ₃ and / or G a 2 0 ₃ 0. components in outer percentage 0 1 3. Claim 1 3, characterized in that it has Omo 1% free .  5. The optical glass according to any one of claims 1 to 4, wherein the water resistance of the powder method is first grade, second grade or third grade. 6. B ₂ 0 ₃ , G e 0 ₂ and so on? ₂ 0 ₅ Total of the components content of Ru der 5 mo 1% or less claims 1-5 optical glass according to any one of. 7. The optical glass according to any one of claims 2 to 6, wherein the R ₂ O component comprises a Li ₂ O and / or Na ₂ O component.  8. The optical glass according to any one of claims 1 to 7, which contains substantially no F component. 9. With 1% mo based on oxide,  5 i 0, 0-1 0% and / or L i ₂ Ο 0 to 30% and Ζ or N a ₂ O 0-20% and / or KΚP ₂ .οΟ 0 1 5% and / or C s 2 Ο 0 to 10% and Ζ or MgO 0 to 10% and / or C a O 0 to 20% and Ζ or B a O 0 to 20% and / or SrO 0 to 20% and / or T io ₂ 0 1 0% and / or N b 2 O 0 to 10% and Ζ or _{T a 2 O 0 ~ 1 0} % and Ζ or WO 3 0 1 0% and / or  ZZ rr ΟO 2 0 to 1 0% and / or Y ₂ o ₃ 0 1 0% and Ζ or Y, O 0 to 10% and / or L a 2 0 ₃ 0~1 0%及Pi or G d ₂ O a 0 to: 10% and / or  S b 2 O 3 0 to 0.5% The optical glass according to any one of claims 1 to 8, comprising each of the components. _{1 0. Y 2 O 3, Yb} 2 O 3, L a 2 O 3 and the optical according to any one of the G d ₂ 0 ₃ component according to claim total content is less than 1 Omo 1% of 1-9 Glass.  1 1. An optical element obtained by precision press-molding the optical glass according to any one of claims 1 to 10.  1 2. A precision press-molding preform comprising the optical glass according to any one of claims 1 to 10.  1 3. An optical element obtained by precision press-molding the preform of claim 12.