JP2010052954A - TeO2-ZnO-B2O3-BASED OPTICAL GLASS - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide TeO<SB>2</SB>-ZnO-B<SB>2</SB>O<SB>3</SB>-based optical glass which has a low glass transition property, which is mass-produced because of being excellent in mold press processability, which has low dispersibility and where a high refractive index property is easily achieved. <P>SOLUTION: The TeO<SB>2</SB>-ZnO-B<SB>2</SB>O<SB>3</SB>-based optical glass has a composition of, by mol%, &ge;0.1% and &lt;40% TeO<SB>2</SB>, 16-40% ZnO, &le;68% ZnO+B<SB>2</SB>O<SB>3</SB>(wherein, B<SB>2</SB>O<SB>3</SB>is contained as an essential ingredient) and &ge;10% ZrO<SB>2</SB>+Ta<SB>2</SB>O<SB>5</SB>+La<SB>2</SB>O<SB>3</SB>and is characterized by having &ge;30 of an Abbe's number &nu;d. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

The present invention relates to a TeO ₂ —ZnO—B ₂ O ₃ optical glass. Specifically, TeO ₂ —ZnO— has a high refractive index nd and Abbe number νd, and is suitable as an optical glass for mold press molding used for optical pickup lenses of various optical disk systems, video cameras, photographing lenses of general cameras, and the like. The present invention relates to B ₂ O ₃ optical glass.

  In recent years, optics used for optical pickup lenses of CD, MD, DVD, and other various optical disk systems, imaging lenses such as digital cameras, video cameras, camera-equipped mobile phones, and transmission / reception lenses used for optical communication. As glass, low dispersion high refractive index optical glass is required. As this type of lens, aspherical lenses are widely used. As a manufacturing method thereof, for example, the following method is known.

  First, molten glass is dropped from the tip of a nozzle to produce droplet glass (droplet molding), and grinding, polishing, and washing are performed to produce preform glass (mold press molding glass material). Alternatively, the molten glass is rapidly cast to produce a glass ingot, which is then ground, polished and washed to produce a preform glass. Subsequently, the preform glass is heated and softened, pressure-molded with a mold having a highly accurate molding surface, and the surface shape of the mold is transferred to the glass to produce a lens. Such a molding method is generally called a mold press molding method, and has been widely adopted in recent years as a method suitable for mass production.

By the way, tellurite-based glass containing TeO ₂ is known as a glass composition system that has a low glass transition point characteristic capable of mold press molding and can achieve a high refractive index characteristic relatively easily. For example, Patent Document 1 discloses a tellurite glass having a glass transition point Tg of 510 ° C. or lower and a refractive index nd of more than 1.97. Patent Document 2 also discloses tellurite glass having a high refractive index nd of about 1.9.
JP 2006-182577 A Japanese Examined Patent Publication No. 1-44461

  The tellurite glass described in Patent Literature 1 has a high refractive index, but has a low Abbe number νd of 29 or less and high dispersion. Patent Document 2 describes a tellurite-based glass having a relatively high refractive index nd or Abbe number νd, but does not disclose a glass satisfying a desired level for both characteristics.

By the way, while TeO ₂ increases the refractive index, it tends to greatly reduce the Abbe's number. Therefore, it is generally difficult to obtain low-dispersion glass with tellurite glass. Further, the inclusion in a large amount and low dispersion characteristics capable to impart B ₂ O ₃ and ZnO into the glass composition in tellurite glass, there is a problem that vitrification tends to be devitrified to become unstable.

In view of the above-mentioned problems of the prior art, the present invention has a low glass transition point property and is excellent in mold press moldability, so that it can be mass-produced, and has low dispersion and achieves a high refractive index property. An object of the present invention is to provide a TeO ₂ —ZnO—B ₂ O ₃ -based optical glass that is easy to be formed.

As a result of intensive studies, the present inventors have found that the above problem can be solved by limiting the content of TeO _{2 in} the tellurite glass and defining the content of other glass components in a specific range. This is proposed as the present invention.

That is, the present invention contains, as a composition, TeO ₂ in mol% of less than 0.1 to 40%, ZnO of 16 to 40%, B ₂ O ₃ as essential components, and ZnO + B ₂ O ₃ of 68% or less. , a _TeO 2 _-ZnO-B 2 _{O 3} based optical glass _{ZrO 2 + Ta 2 O 5 +} La 2 O 3 is 10% or more, and wherein the Abbe number νd of 30 or more _TeO 2 -ZnO -B about ₂ O ₃ based optical glass. Here, “containing B ₂ O ₃ as an essential component” means containing 0.1% or more of B ₂ O ₃ .

_TeO 2 _-ZnO-B 2 _{O 3} based optical glass of the present invention, since containing ZnO 16% or more, it is easy to achieve a suitable low glass transition temperature Tg and liquidus temperature TL to press molding. Further, since TeO ₂ is contained, it is easy to obtain a low glass transition point characteristic capable of being mold-pressed.

The TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention contains, as essential components, TeO ₂ for increasing the refractive index of glass, ZnO for reducing the dispersion of glass, and B ₂ O ₃ . Furthermore, it contains at least one of La ₂ O ₃ , ZrO ₂ , and Ta ₂ O ₅ that can lower the dispersion more easily than TeO ₂ . For this reason, it is possible to manufacture an optical lens that has an Abbe number νd of 30 or more, has low dispersion characteristics, easily achieves high refractive index characteristics, and can reduce the size and functionality of optical devices. .

Therefore, the TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention includes optical pickup lenses for CD, MD, DVD, and other various optical disc systems, imaging lenses such as digital cameras, video cameras, camera-equipped mobile phones, It is suitable as a glass material for mold press molding for optical lenses such as transmission / reception lenses used in optical communication.

Second, the TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention has a refractive index nd of 1.82 or more.

Third, in the TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention, B ₂ O ₃ / ZnO is preferably 0.76 to 1.5.

Fourthly, the TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention preferably contains 26 to 40% of ZnO.

Fifth, the TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention preferably contains 2 to 50% of B ₂ O ₃ .

Sixth, the TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention further includes Nb ₂ O ₅ , Gd ₂ O ₃ , Y ₂ O ₃ , Yb ₂ O ₃ , SiO ₂ , Al ₂ O _3. It is preferable to contain at least one selected from WO ₃ , TiO ₂ , CaO, BaO, SrO, Li ₂ O, Na ₂ O and K ₂ O.

Seventh, the TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention preferably has a Nb ₂ O ₅ content of less than 7%.

By limiting the content of Nb ₂ O ₅ in the glass composition in this way, it becomes easy to achieve a high Abbe number.

Eighth, the present invention provides, as another form, a _molar%, TeO less than _{2 0.1~40%, La 2 O 3} 0~40%, ZnO 16~40%, B 2 O 3 2~50% _(However, B ₂ O 3 / ZnO is 0.76 to 1.5, and ZnO ₊ B 2 _{O 3} is less _{68%), Nb 2 O 5} 0~25%, WO 3 0~45%, TiO 2 0~10 %, ZrO ₂ 0-20%, SiO ₂ 0-5%, Al ₂ O ₃ 0-5%, Ta ₂ O ₅ 0-15%, CaO 0-5%, BaO 0-5%, SrO 0-5 %, Li ₂ O 0-5%, Na ₂ O 0-5%, K ₂ O 0-5%, and substantially free of PbO, Tl ₂ O and HfO _{The present invention} relates to a _2- ZnO—B ₂ O ₃ optical glass.

The TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention is easy to achieve a low glass transition point Tg and a liquidus temperature TL suitable for mold press molding, and has a low glass transition point characteristic of mold press molding. It has a feature that it is excellent in mass productivity of preform glass. In addition, the TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention is easy to achieve low dispersion and high refractive index, and produces an optical lens capable of reducing the size and increasing the functionality of an optical device. Is possible.

The TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention is preferable from the viewpoint of the environment because it does not substantially contain environmentally hazardous substances such as PbO, Tl ₂ O and HfO. Here, “substantially free of PbO, Tl ₂ O and HfO” means that these components are each 0.001% or less.

Ninth, the TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention preferably contains 0.1 to 40% of La ₂ O ₃ .

Tenth, the TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention preferably has a glass transition point Tg of 630 ° C. or lower.

Eleventh, the TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention preferably has a liquidus temperature TL of 1050 ° C. or lower.

Twelfth, mold press molding glass material of the present invention is characterized by comprising the one of _TeO 2 _-ZnO-B 2 _{O 3} based optical glass.

  13thly, the optical lens of this invention consists of the said glass material for mold press molding, It is characterized by the above-mentioned.

The TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention contains, as a composition, TeO ₂ in mol%, less than 0.1 to 40%, ZnO 16 to 40%, and B ₂ O ₃ as essential components. To do.

  The reason why the content of each component is limited as described above will be described below. Unless otherwise specified, the following “%” means “mol%”.

TeO ₂ is an effective component for obtaining a glass having a high refractive index, and is also a component that lowers the glass transition point Tg. Furthermore, it also has the function of facilitating vitrification. The content of TeO ₂ is less than 0.1 to 40%, preferably 1 to 30%, more preferably 3 to 20%, and still more preferably 5 to 20%. Moreover, it becomes difficult to obtain a low glass transition point characteristic. If the TeO ₂ content is less than 0.1%, it is difficult to obtain a glass with a high refractive index. On the other hand, when the content of TeO ₂ is 40% or more, the mold press mold tends to deteriorate and the life tends to be shortened. Moreover, it becomes difficult to obtain low dispersion characteristics.

If the TeO ₂ content is reduced, it may be difficult to increase the refractive index of the glass. However, as will be described later, the shortage of the refractive index nd is caused by other components such as Nb ₂ O ₅ and Ta ₂ O. ₅ , WO ₃ , TiO _2, ZrO _{2 and the} like can be supplemented by appropriate addition. Similarly, when the content of TeO ₂ is decreased, the glass transition point Tg tends to increase. For example, by adding Li ₂ O, K ₂ O, Na ₂ O, BaO, CaO, SrO, or the like, the glass transition point Tg is increased. Can be reduced.

  ZnO is a component that lowers the glass and lowers the glass transition point Tg. The content of ZnO is 16 to 40%, preferably 20 to 40%, more preferably 26 to 40%, and still more preferably 26 to 35%. If the ZnO content is less than 16%, the above effect is difficult to obtain. On the other hand, when the content of ZnO exceeds 40%, vitrification tends to be remarkably prevented.

B ₂ O _{3 is} also a component that lowers the glass transition point Tg while reducing the glass dispersion. It is also a component that stabilizes glass. B ₂ O ₃ is contained as an essential component, and the content thereof is preferably 2 to 50%, more preferably 10 to 50%, still more preferably 25 to 50%, and particularly preferably 25 to 40%. If the B ₂ O ₃ content is less than 2%, the effect is difficult to obtain. On the other hand, if the content of B ₂ O ₃ exceeds 50%, the refractive index nd of the glass decreases, and it becomes difficult to maintain a high refractive index characteristic of, for example, a refractive index nd of 1.82 or more.

In TeO _{2 -ZnO-B 2 O 3} based optical glass, from the viewpoint of obtaining a glass of low dispersion, it is preferred to incorporate as much as possible the ZnO and _B 2 _{O 3,} the content of ZnO and _B 2 _{O 3} If the amount is increased, the stability of the glass is impaired, and the glass tends to be easily devitrified or vitrified. From such a viewpoint, ZnO + B ₂ O ₃ is limited to 68% or less, preferably 65% or less, more preferably 60% or less. From the viewpoint of obtaining a sufficiently low dispersion effect, ZnO + B ₂ O ₃ is preferably 30% or more, more preferably 43% or more, and even more preferably 50% or more.

In order to suppress destabilization of the glass accompanying an increase in the content of ZnO and B ₂ O ₃ , it is effective to limit the ratio of the content of B ₂ O ₃ and ZnO. Specifically, B ₂ O ₃ / ZnO is preferably 0.76 to 1.5, more preferably 0.77 to 1.5, still more preferably 0.78 to 1.2, and particularly preferably 0.8. Limited to ~ 1.2.

As will be described later, in addition to B ₂ O ₃ and ZnO, for example, La ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ , Yb ₂ O ₃ , SiO ₂ , Al ₂ O _3, or the like is necessary. It is also possible to compensate for the effect of low dispersion of the glass by appropriately adding them.

_TeO 2 _-ZnO-B 2 _{O 3} based optical glass of the present invention may further contain _La 2 _{O 3} in addition to the above components. La ₂ O ₃ is an effective component for achieving low dispersion while maintaining a high refractive index. The content of La ₂ O ₃ is 0 to 40%, preferably 0.1 to 40%, more preferably 0.1 to 30%, still more preferably 5 to 25%, and particularly preferably 8 to 20%. By increasing the content of La ₂ O ₃ , it becomes easy to make the low dispersion characteristic, specifically, the Abbe number νd 30 or more. However, if the content of La ₂ O ₃ exceeds 40%, the glass Tends to be difficult.

The TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention can further contain at least one selected from Nb ₂ O ₅ , Ta ₂ O ₅ , WO ₃ , TiO ₂ and ZrO ₂ . These components have the effect of increasing the refractive index nd. Hereinafter, each component will be described.

Nb ₂ O ₅ is a component that has a large effect of increasing the refractive index nd of the glass. However, if it is contained in a large amount, it tends to be devitrified and the Abbe number νd tends to decrease. Therefore, the content of Nb ₂ O ₅ is 0 to 25%, preferably 0.1 to 15%, more preferably 1 to 10%. In particular, in order to obtain a glass having a high Abbe number, the content of Nb ₂ O ₅ is preferably less than 7%.

Ta ₂ O ₅ is a component that increases the refractive index nd of the glass. However, when contained in a large amount, vitrification tends to be remarkably prevented. Therefore, the content of Ta ₂ O ₅ is 0 to 15%, preferably 0.1 to 10%.

WO ₃ is a component that increases the refractive index nd of the glass and stabilizes the glass. However, if contained in a large amount, the glass tends to become thermally unstable. Therefore, the content of WO ₃ is 0 to 45%, preferably 0 to 20%, more preferably 0.1 to 10%.

TiO ₂ is a component that has a remarkable effect of increasing the refractive index nd of glass. However, when contained in a large amount, vitrification tends to be remarkably prevented. Therefore, the content of TiO ₂ is 0 to 10%, preferably 0.1 to 5%.

ZrO ₂ is a component that increases the refractive index nd of the glass. However, when contained in a large amount, vitrification tends to be remarkably prevented. Therefore, the content of ZrO ₂ is 0 to 20%, preferably 0 to 10%, more preferably 0.1 to 5%.

In the TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention, ZrO ₂ + Ta ₂ O ₅ + La ₂ O ₃ is limited to 10% or more, preferably 15% or more. When ZrO ₂ + Ta ₂ O ₅ + La ₂ O ₃ is less than 10%, it is difficult to obtain a glass satisfying a desired level of both high refractive index and low dispersion characteristics.

The TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention is at least one selected from Gd ₂ O ₃ , Y ₂ O ₃ , Yb ₂ O ₃ , SiO ₂ and Al ₂ O ₃ in addition to the above components. Seeds can be included. These components have the effect of reducing the dispersion of the glass. Hereinafter, each component will be described.

Gd ₂ O ₃ is an effective component for achieving low dispersion while maintaining a high refractive index. The content of Gd ₂ O ₃ is 0 to 15%, preferably 0 to 10%, more preferably 0.1 to 5%.

Y ₂ O ₃ is a component for reducing the dispersion of glass. The content of Y ₂ O ₃ is 0 to 15%, preferably 0 to 10%, more preferably 0.1 to 5%.

Yb ₂ O _{3 is} also a component that lowers the glass. The content of Yb ₂ O ₃ is 0 to 15%, preferably 0 to 10%, more preferably 0.1 to 5%.

SiO ₂ also has the effect of reducing the dispersion of the glass, but as the content increases, the glass tends to become thermally unstable. Therefore, the content of SiO ₂ is 0 to 5%, preferably 0.1 to 2%.

Al ₂ O ₃ also has the effect of reducing the dispersion of the glass, but as the content increases, the glass tends to become thermally unstable. Therefore, the content of Al ₂ O ₃ is 0 to 5%, preferably 0.1 to 2%.

The TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention further contains at least one selected from Li ₂ O, K ₂ O, Na ₂ O, BaO, CaO, and SrO in addition to the above components. Can do. These components can be used for fine adjustment of the refractive index nd and the glass transition point Tg. However, since the refractive index nd is greatly reduced by adding a small amount of any component, it is not preferable to add a large amount. The contents of these components are each 0 to 5%, preferably 0.1 to 3%.

The TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention can further contain various components in addition to the above components. For example, GeO ₂ , P ₂ O ₅ , and Ga ₂ O ₃ can be added.

GeO ₂ can be added for the purpose of stabilizing the glass and improving the refractive index. However, since it is a rare raw material, if it is contained in a large amount, the raw material cost will rise. Therefore, even if it is used, its content is limited. Specifically, the content of GeO ₂ is 0 to 5%, preferably 0 to 3%, more preferably 0 to 1%. In particular, it is preferably 0.001% or less.

P ₂ O ₅ can be added for the purpose of adjusting the glass transition point Tg and the viscosity. However, when it contains abundantly, it will become easy to produce the fall of the weather resistance of glass, and devitrification. Therefore, even if it is used, its content is limited. Specifically, the content of P ₂ O ₅ is 0 to 10%, preferably 0.1 to 5%.

Ga ₂ O ₃ can be added for the purpose of stabilizing the glass and adjusting the refractive index. However, since it is a rare raw material and expensive, if it is contained in a large amount, the raw material cost will rise. Therefore, from the viewpoint of mass productivity, the content is less than 3%, preferably 1% or less, more preferably 0.001% or less.

In addition, since Er causes glass coloring, it is preferable not to contain substantially. Specifically, it is preferably 0.001% or less in terms of Er ₂ O ₃ content.

Moreover, since PbO, Tl ₂ O, and HfO are environmentally hazardous substances, it is preferable that they are not substantially contained. Specifically, these components are each preferably 0.001% or less.

The TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention has an Abbe number νd of 30 or more, preferably 34 or more, more preferably 35 or more, still more preferably 36 or more, and particularly preferably 37 or more.

The TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention preferably has a refractive index nd of 1.82 or more, more preferably 1.84 or more, still more preferably 1.86 or more, and particularly preferably 1 .87 or more.

In another embodiment, the present invention may include, in mol%, TeO ₂ 0.1 to less than 40%, La ₂ O ₃ 0 to 40%, ZnO 16 to 40%, B ₂ O ₃ 2 to 50% (provided that B ₂ O ₃ / ZnO is 0.76 to 1.5, and ZnO ₊ B 2 _{O 3} is less _{68%), Nb 2 O 5} 0~25%, WO 3 0~45%, TiO 2 0~10%, ZrO 2 _{0~20%, SiO 2 0~5%,} Al 2 O 3 0~5%, Ta 2 O 5 0~15%, CaO 0~5%, BaO 0~5%, SrO 0~5%, Li 2 TeO ₂ —ZnO— containing O 0 to 5%, Na ₂ O 0 to 5%, K ₂ O 0 to 5% and substantially free of PbO, Tl ₂ O, and HfO The present invention relates to B ₂ O ₃ optical glass.

  The reason for limiting the glass composition in this way is the same as described above.

Further, in the glass composition, more preferably in the range of, in _{mole%, TeO 2 0.1~20%, La} 2 O 3 0.1~30%, ZnO 26~40%, B 2 O 3 25~50% , _(wherein, B ₂ O 3 / value of ZnO is from 0.76 to 1.5, and ZnO ₊ B 2 _{O 3} is less _{68%), Nb 2 O 5} 0~25%, WO 3 0~45%, TiO 2 _{0~10%, ZrO 2 0~10%,} SiO 2 0~5%, Al 2 O 3 0~5%, Ta 2 O 5 0~9%, CaO 0~5%, BaO 0~5%, SrO _{0~5%, Li 2 O 0~5%} , Na 2 O 0~5%, containing K 2 O 0~5%, PbO, include those substantially free of Tl ₂ O and HfO.

The TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention has a glass transition point Tg of preferably 630 ° C. or less, more preferably 600 ° C. or less. The liquidus temperature TL is 1050 ° C. or lower, more preferably 1040 ° C. or lower. It is preferable from the viewpoint of preform glass mass productivity that the glass transition point Tg or the liquidus temperature TL satisfy this range.

Next, a method for producing an optical glass such as an optical pickup lens or a photographing lens using the TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention will be described.

  First, after preparing a glass raw material so that it may become a desired composition, it fuse | melts with a glass melting furnace.

  Next, molten glass is dripped from the tip of the nozzle to produce a glass droplet once to obtain a preform glass. Alternatively, a molten glass is rapidly cast to produce a glass block, which is then ground, polished and washed to obtain a preform glass.

  Subsequently, the preform glass is put into a precision-worked mold, and pressure molding is performed while heating until a softened state is obtained, and the surface shape of the mold is transferred to the glass. In this way, an optical pickup lens and a photographing lens can be obtained.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to these Examples.

  Tables 1 to 3 show Examples 1 to 12 and Comparative Examples 1 to 5 of the present invention.

  Each sample was produced as follows.

  First, the glass raw material prepared so that it might become the composition of Tables 1-3 was put into the platinum crucible, and it melted at 1080 degreeC for 2 hours, respectively. Next, the molten glass was poured onto a carbon plate, cooled and solidified, and then annealed to produce a glass sample. Various characteristics were evaluated for the glass samples thus obtained. The results are shown in Tables 1-3.

  The refractive index nd is indicated by a measured value at the d-line (wavelength: 587.6 nm) of a helium lamp using a refractometer (KPR-200 manufactured by Kalnew).

  Abbe number νd was determined using a refractometer (KPR-200 manufactured by Kalnew), helium lamp d-line, hydrogen lamp F-line (wavelength: 486.1 nm), and hydrogen lamp C-line (wavelength: 656.3 nm). ) Were measured as the values of {(nd-1) / (nF-nC)} when nd, nF, and nC were measured.

  The liquidus temperature TL is obtained by pulverizing a glass sample to a particle size of 300 to 500 μm, putting it in a platinum boat and heat-treating it in a temperature gradient furnace for 12 hours (crystal foreign matter). ) As observed temperature.

  The glass transition point Tg was determined from the intersection of the low temperature line and the high temperature line in the thermal expansion curve.

  As apparent from Tables 1 to 3, in Examples 1 to 12, the Abbe number νd is 30.0 to 39.1, the refractive index nd is 1.860 to 1.972, and low dispersion characteristics and high refractive index characteristics are obtained. You can see that both are satisfied. Moreover, the glass transition point Tg is 528-578 degreeC, It has confirmed that mold press molding was fully possible. Further, the liquidus temperature TL was as good as 1050 ° C. or lower.

On the other hand, Comparative Examples 1 and 3 contained TeO ₂ in a large amount of 40% or more, and Comparative Example 4 had a low Abbe number νd and high dispersion because the ZnO content was less than 16%. Comparative Example 2 is less than 16% content of _ZnO, for B 2 _{O 3} and ZnO ratio _B 2 _O 3 / ZnO in is out of range of 0.76 to 1.5, part crystals precipitated. Comparative Example 5 was not vitrified because ZnO + B ₂ O ₃ was greater than 68%.

The TeO ₂ —ZnO—B ₂ O ₃ optical glass of the present invention is an optical pickup lens for a CD, MD, DVD, and other various optical disk systems, an imaging lens for a digital camera, a video camera, a camera-equipped mobile phone, an optical communication, etc. It is suitable as glass for glass materials of optical lenses such as transmission / reception lenses used in the above. In particular, it is suitable as a glass material glass for optical lenses produced by mold press molding. It can also be used as a glass glass material formed by a molding method other than mold press molding.

Claims (13)

As a composition, TeO ₂ in mol% is less than 0.1 to 40%, ZnO is contained in 16 to 40%, B ₂ O ₃ is an essential component, and ZnO + B ₂ O ₃ is 68% or less, ZrO ₂ + Ta ₂ O. ₅ + _La 2 _{O 3} is a _TeO 2 _-ZnO-B 2 _{O 3} based optical glass not less than _{10%, TeO 2 -ZnO-B 2 O} 3 system, wherein the Abbe number νd of 30 or more Optical glass. _TeO 2 _-ZnO-B 2 _{O 3} based optical glass according to claim 1, the refractive index nd is equal to or is 1.82 or more. B ₂ O ₃ / ZnO is according to claim 1 or 2, characterized in that a _{0.76~1.5 TeO 2 -ZnO-B 2 O} 3 based optical glass. _TeO 2 _-ZnO-B 2 _{O 3} based optical glass according to any one of claims 1 to 3, characterized in that it contains ZnO 26 to 40%. _TeO 2 _-ZnO-B 2 _{O 3} based optical glass according to claim 1, the B ₂ O _3, characterized in that it contains 2 to 50%. Further, Nb ₂ O ₅ , Gd ₂ O ₃ , Y ₂ O ₃ , Yb ₂ O ₃ , SiO ₂ , Al ₂ O ₃ , WO ₃ , TiO ₂ , CaO, BaO, SrO, Li ₂ O, Na ₂ O and The TeO ₂ —ZnO—B ₂ O ₃ optical glass according to claim 1, comprising at least one selected from K ₂ O. _TeO 2 _-ZnO-B 2 _{O 3} based optical glass according to any one of claims 1 to 6, the content of Nb ₂ O ₅ is equal to or less than 7%. In _mole%, TeO less than _{2 0.1~40%, La 2 O 3} 0~40%, ZnO 16~40%, B 2 O 3 2~50% ( _however, B ₂ O 3 / ZnO 0.76 1.5 and ZnO + B ₂ O ₃ is 68% or less), Nb ₂ O ₅ 0-25%, WO ₃ 0-45%, TiO ₂ 0-10%, ZrO ₂ 0-20%, SiO ₂ 0 _{5%, Al 2 O 3 0~5} %, Ta 2 O 5 0~15%, CaO 0~5%, BaO 0~5%, SrO 0~5%, Li 2 O 0~5%, Na 2 O A TeO ₂ —ZnO—B ₂ O ₃ based optical glass containing a composition of 0 to 5%, K ₂ O 0 to 5%, and substantially free of PbO, Tl ₂ O and HfO. _TeO 2 _-ZnO-B 2 _{O 3} based optical glass according to claim 8, characterized in that it contains La ₂ O ₃ 0.1~40%. _TeO 2 _-ZnO-B 2 _{O 3} based optical glass according to any one of claims 1 to 9, wherein the glass transition point Tg of 630 ° C. or less. _TeO 2 _-ZnO-B 2 _{O 3} based optical glass according to any one of claims 1 to 10 liquidus temperature TL is equal to or is 1050 ° C. or less. A glass material for mold press molding comprising the TeO ₂ —ZnO—B ₂ O ₃ optical glass according to claim 1.   An optical lens comprising the glass material for mold press molding according to claim 12.