JP2009286674A - Optical glass, preform for precision press molding, and optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical glass which is easily softened at low temperatures, and easy to be press-molded, notwithstanding that its refractive index (n<SB>d</SB>) and Abbe number (ν<SB>d</SB>) are each in a desired range, and an optical element and a preform for precision press molding using the optical glass. <P>SOLUTION: The optical glass for precision press molding contains 5.0-50% of B<SB>2</SB>O<SB>3</SB>, 5.0-40% of TiO<SB>2</SB>, 1.0-40% of ZnO, and 5.0-20% of La<SB>2</SB>O<SB>3</SB>in mol% of the total mass of the glass in terms of the oxide. The preform for precision press molding and the optical element use the optical glass as a base material. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical glass, a precision press-molding preform, and an optical element.

  In recent years, the digitization and high definition of devices that use optical systems have been rapidly progressing, and the precision of optical elements such as lenses used in various optical devices, including photography devices such as digital cameras and video cameras, The demand for light weight and downsizing is increasing.

Among optical glasses for producing an optical element, in particular, it has a high refractive index ( _nd ) of 1.75 or more and 2.20 or less that can reduce the weight and size of the optical element, and 21.0 or more. The demand for high refractive index glass having an Abbe number (ν _d ) of 40.0 or less is greatly increasing. As such a high refractive index glass, a glass composition having a refractive index (n _d ) of 1.8 and an Abbe number (ν _d ) of 35 or less, as typified by Patent Document 1, is known. Yes.
JP 2006-137645 A

  As a method for manufacturing such an optical element, a preform material obtained by cutting and polishing a gob or a glass block, or a preform material formed by a known floating molding or the like is heated and softened to have a highly accurate molding surface. The pressure molding method (precision press molding) is used.

  However, many of the glasses disclosed in Patent Document 1 have a high glass transition point (Tg), and the solubility of these glasses was low. Moreover, many of the glasses disclosed in Patent Document 1 have a high yield point (At), and these glasses are difficult to press-mold. For those reasons, a preform material is produced from the glass of Patent Document 1, and even if an optical element is produced by heat-softening and press-molding the preform material, the temperature at which the preform material is heat-softened and press-molded is adjusted. Since it is necessary to increase the optical element, the produced optical element is colored or the optical characteristics of the optical element are affected.

The present invention has been made in view of the above problems, and its object is to soften at a low temperature while the refractive index (n _d ) and the Abbe number (ν _d ) are within the desired ranges. It is to obtain an optical glass that is easy to perform and press molding, an optical element using the optical glass, and a preform for precision press molding.

In order to solve the above-mentioned problems, the present inventors have conducted intensive studies, and as a result, B ₂ O ₃ component, TiO ₂ component, ZnO component, and La ₂ O ₃ component are used in combination, and B ₂ O ₃ component , TiO ₂ component, ZnO component, and La ₂ O ₃ component are contained within a predetermined range to increase the refractive index of the glass, obtain a desired Abbe number, and obtain a glass transition point ( It was found that Tg) was lowered and the yield point (At) was lowered, and the present invention was completed. Specifically, the present invention provides the following.

(1) the glass the total amount of substance of the oxide composition in terms of, 5.0 to 50.0% of _B 2 _{O 3} component in mol%, the TiO ₂ component from 5.0 to 40.0%, the ZnO component Optical glass containing 1.0 to 40.0% and La ₂ O ₃ component 5.0 to 20.0%.

(2) SiO ₂ component 0 to 10.0% and / or Nb ₂ O ₅ component 0 to 20.0% in mol% with respect to the total amount of glass in the oxide conversion composition
(1) optical glass which further contains each component of.

(3) the glass the total amount of substance of the oxide composition in terms of, 0~5.0% _P 2 _{O 5} component in mol% and / or GeO ₂ component from 0 to 10.0% and / or _Al 2 _{O 3} component 0 to 10.0%
(1) or the optical glass in any one of (2) which further contains each component of.

(4) The optical glass according to (3), wherein the ratio of the substance amount of the oxide equivalent composition (B ₂ O ₃ + P ₂ O ₅ ) / (SiO ₂ + GeO ₂ + Al ₂ O ₃ ) is 6.0 or more.

(5) the glass the total amount of substance of the oxide composition in terms of, Li ₂ O component from 0 to 20.0% and / or Na ₂ O component from 0 to 20.0% and / or _{K 2} O ingredient 0 mol% 20.0% and / or Cs ₂ O component from 0 to 20.0%
The optical glass according to any one of (1) to (4), further comprising:

(6) The optical glass according to (5), wherein the total amount of Li ₂ O + Na ₂ O + K ₂ O + Cs ₂ O with respect to the total amount of glass having an oxide conversion composition exceeds 0% and is 20.0% or less.

(7) 0 to 20.0% of MgO component and / or 0 to 20.0% of CaO component and / or 0 to 20.0% of SrO component and in mol% with respect to the total amount of glass in the oxide conversion composition / Or BaO component 0 to 20.0%
The optical glass according to any one of (1) to (6), further containing each component of

  (8) The optical glass according to (7), wherein the amount of MgO + CaO + SrO + BaO + ZnO is 1.0% to 25.0% with respect to the total amount of glass having an oxide conversion composition.

(9) TeO ₂ component 0 to 10.0% and / or ZrO ₂ component 0 to 15.0% and / or Ta ₂ O ₅ component 0% by mol% with respect to the total amount of glass in the oxide conversion composition 20.0% and / or WO ₃ component 0-20.0% and / or Y ₂ O ₃ component 0-10.0% and / or Gd ₂ O ₃ component 0-15.0% and / or Yb ₂ O ₃ components 0 to 20.0% and / or Sb ₂ O ₃ components 0 to 1.0%
The optical glass according to any one of (1) to (8), further comprising:

(10) Any one of (1) to (9) having a refractive index (n _d ) of 1.75 or more and 2.20 or less and an Abbe number (ν _d ) of 21.0 or more and 40.0 or less Optical glass.

  (11) The optical glass according to any one of (1) to (10), which has a glass transition point (Tg) of 620 ° C. or lower.

  (12) The optical glass according to any one of (1) to (11), wherein a yield point (At) is 640 ° C. or lower.

  (13) An optical element having the optical glass according to any one of (1) to (12) as a base material.

  (14) An optical element produced by precision press-molding the optical glass according to any one of (1) to (12).

  (15) A precision press-molding preform comprising the optical glass according to any one of (1) to (12).

  (16) An optical element produced by precision press-molding the precision press-molding preform described in (15).

According to the present invention, the B ₂ O ₃ component, the TiO ₂ component, the ZnO component, and the La ₂ O ₃ component are used in combination, and the B ₂ O ₃ component, the TiO ₂ component, the ZnO component, and the La ₂ O ₃ component are contained. By controlling the rate within a predetermined range, the refractive index of the glass is increased, the desired Abbe number is obtained, the glass transition point (Tg) is lowered, and the yield point (At) is lowered. The difference ΔT between the transition point (Tg) and the crystallization start temperature (Tx) increases. Therefore, an optical glass having a refractive index (n _d ) and an Abbe number (ν _d ) within a desired range, being easily softened at a low temperature, easy to press-mold, and having high thermal stability, and A precision press-molding preform and optical element using can be obtained.

In the optical glass of the present invention, the B ₂ O ₃ component is 5.0 to 50.0% and the TiO ₂ component is 5.0 to 40.0% in mol% with respect to the total amount of the glass having an oxide conversion composition. The ZnO component is contained in an amount of 1.0 to 40.0%, and the La ₂ O ₃ component is contained in an amount of 5.0 to 20.0%. B ₂ O ₃ component, TiO ₂ component, ZnO component, and La ₂ O ₃ component are used in combination, and the content ratios of B ₂ O ₃ component, TiO ₂ component, ZnO component, and La ₂ O ₃ component are within a predetermined range. By suppressing the glass to a high refractive index, a desired Abbe number can be obtained, the glass transition point (Tg) is lowered, the yield point (At) is lowered, and the glass transition point (Tg) The difference ΔT from the crystallization start temperature (Tx) increases. Therefore, it is easy to soften at low temperatures, easy to perform press molding, the thermal stability is high, and 1.75 or more 2.20 or less of the refractive index _{(n d)} and 21.0 or 40.0 or less Abbe An optical glass having a number (ν _d ) can be obtained.

  Hereinafter, embodiments of the optical glass of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present invention. be able to. In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the meaning of invention is not limited.

[Glass component]
The composition range of each component constituting the optical glass of the present invention is described below. In the present specification, unless otherwise specified, the content of each component is all expressed in mol% with respect to the total amount of glass having an oxide equivalent composition. Here, the “oxide equivalent composition” means that the oxide, composite salt, metal fluoride, etc. used as the raw material of the glass component of the present invention are all decomposed and changed into oxides when melted. It is the composition which described each component contained in glass by making the total substance amount of the said production | generation oxide into 100 mol%.

<About essential and optional components>
The B ₂ O ₃ component is a component constituting a glass network. In particular, by setting the content of B ₂ O ₃ component in more than 5.0%, it is possible to enhance the stability of the glass. On the other hand, a desired refractive index can be easily obtained by setting the content ratio of the B ₂ O ₃ component to 50.0% or less. Therefore, the content of the B ₂ O ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 5.0%, more preferably 7.0%, and most preferably 10.0%, and preferably The upper limit is 50.0%, more preferably 47.0%, and most preferably 45.0%. The B ₂ O ₃ component can be contained in the glass using, for example, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ .10H ₂ O, BPO ₄ or the like as a raw material.

TiO ₂ component is a component for increasing the refractive index of the glass. In particular, the desired refractive index of the glass can be easily obtained by setting the content of the TiO ₂ component to 5.0% or more. On the other hand, by setting the content of the TiO ₂ component below 40.0%, enhance the stability of the glass, it is possible to suppress the coloration of the glass. Accordingly, the content of the TiO ₂ component with respect to the total amount of glass in the oxide conversion composition is preferably 5.0%, more preferably 7.0%, and most preferably 10.0%, and preferably 40. The upper limit is 0%, more preferably 37.0%, and most preferably 35.0%. TiO ₂ component may be contained in the glass by using as the starting material for example TiO ₂ or the like.

The ZnO component is a component that increases the refractive index of the glass and further lowers the glass transition point (Tg). In particular, the refractive index and glass transition point (Tg) of glass can be easily maintained within a desired range by setting the content of the ZnO component to 1.0% or more. On the other hand, the stability of glass can be improved by making the content rate of a ZnO component into 40.0% or less. Therefore, the content of the ZnO component with respect to the total amount of glass in the oxide conversion composition is preferably 1.0%, more preferably 3.0%, and most preferably 4.0%, preferably 40.0. %, More preferably 37.0%, and most preferably 35.0%. The ZnO component can be contained in the glass using, for example, ZnO, ZnF ₂ or the like as a raw material.

The La ₂ O ₃ component is a component that increases the refractive index of the glass and decreases the dispersion of the glass. In particular, by setting the content of the La ₂ O ₃ component to 5.0% or more, it is possible to easily obtain desired high refractive index and low dispersion characteristics. On the other hand, by setting the content of _La 2 _{O 3} component below 20.0%, it is possible to increase the stability of the glass. Therefore, the content of La ₂ O ₃ component with respect to the total amount of glass in oxide conversion composition is preferably 5.0%, more preferably 7.0%, and most preferably 10.0%, and preferably The upper limit is 20.0%, more preferably 17.0%, and most preferably 15.0%. The La ₂ O ₃ component can be contained in the glass using, for example, La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ O (X is an arbitrary integer) or the like as a raw material.

The SiO ₂ component is a component that promotes stable glass formation, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the SiO ₂ component to 10.0% or less, it is possible to make it difficult to lower the refractive index of the glass and to raise the yield point of the glass. Therefore, the upper limit of the content of the SiO ₂ component with respect to the total amount of glass in the oxide conversion composition is preferably 10.0%, more preferably 7.0%, and most preferably 5.0%. SiO ₂ component may be contained in the glass by using as a raw material such as _{SiO 2, K 2 SiF 6,} Na 2 SiF 6 or the like.

Nb ₂ O ₅ component is a component that raises the refractive index of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of the Nb ₂ O ₅ component to 20.0% or less, it is possible to increase the stability of the glass and make it difficult to raise the liquidus temperature of the glass. Therefore, the content of the Nb ₂ O ₅ component is preferably 20.0%, more preferably 17.0%, and most preferably 15.0% with respect to the total amount of glass in the oxide equivalent composition. The Nb ₂ O ₅ component can be contained in the glass using, for example, Nb ₂ O ₅ as a raw material.

P ₂ O ₅ component is a component constituting the network of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of the P ₂ O ₅ component to 5.0% or less, the devitrification tendency can be reduced and the stability of the glass can be increased. Therefore, the content of the P ₂ O ₅ component with respect to the total amount of glass in the oxide conversion composition is preferably 5.0%, more preferably 3.0%, and most preferably 2.0%. The P ₂ O ₅ component can be contained in the glass using, for example, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , H ₃ PO ₄ or the like as a raw material. .

The GeO ₂ component is a component that constitutes a glass network and improves the stability and refractive index of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the GeO ₂ component is 10.0% or less, it is possible to reduce the material cost of the glass. Accordingly, the content of the GeO ₂ component with respect to the total amount of glass in the oxide conversion composition is preferably 10.0%, more preferably 5.0%, and most preferably 3.0%. The GeO ₂ component can be contained in the glass using, for example, GeO ₂ as a raw material.

The Al ₂ O ₃ component is a component that increases the devitrification resistance of the glass, and is an optional component in the optical glass of the present invention. In particular, by making the content of the Al ₂ O ₃ component 10.0% or less, a desired refractive index can be easily obtained. Therefore, the upper limit of the content of the Al ₂ O ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 10.0%, more preferably 5.0%, and most preferably 3.0%. The Al ₂ O ₃ component can be contained in the glass using, for example, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ or the like as a raw material.

In the optical glass of the present invention, it is preferable that the substance amount ratio of the substance amount sum (B ₂ O ₃ + P ₂ O ₅ ) to the substance amount sum (SiO ₂ + GeO ₂ + Al ₂ O ₃ ) is 6.0 or more. By setting the amount ratio to 6.0 or more, the content of the oxide that lowers the glass transition point (Tg) among the oxides constituting the glass network is relatively increased. The glass transition point (Tg) can be lowered while maintaining. Therefore, the lower limit of the amount ratio of the substance in the oxide conversion composition is preferably 6.0, more preferably 6.5, and most preferably 6.8.

Li 2 _O component is a component for glass transition point (Tg) lower, are optional components of the optical glass of the present invention. In particular, when the content ratio of the Li ₂ O component is 20.0% or less, the refractive index of the glass is hardly lowered and the stability of the glass can be improved. Therefore, the upper limit of the content of the Li ₂ O component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%. The Li ₂ O component can be contained in the glass using, for example, Li ₂ CO ₃ , LiNO ₃ , LiF or the like as a raw material.

Na 2 _O component is a component for improving the meltability of the glass, an optional component of the optical glass of the present invention. In particular, when the content of the Na ₂ O component is 20.0% or less, the refractive index of the glass is hardly lowered and the stability of the glass can be improved. Therefore, the upper limit of the content ratio of the Na ₂ O component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%. The Na ₂ O component can be contained in the glass using, for example, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ or the like as a raw material.

K 2 _O component is a component for improving the meltability of the glass, an optional component of the optical glass of the present invention. In particular, when the content of the K ₂ O component is 20.0% or less, the refractive index of the glass is hardly lowered and the stability of the glass can be improved. Therefore, the upper limit of the content of the K ₂ O component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%. The K ₂ O component can be contained in the glass using, for example, K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ or the like as a raw material.

Cs 2 _O component is a component for improving the meltability of the glass, an optional component of the optical glass of the present invention. In particular, when the content of the Cs ₂ O component is 20.0% or less, the refractive index of the glass is hardly lowered and the stability of the glass can be improved. Therefore, the upper limit of the content of the Cs ₂ O component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%. Cs ₂ O component may be contained in the glass by using as the starting material for example _Cs 2 _{CO 3,} CsNO 3, and the like.

In the optical glass of the present invention, the content amount of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, K, and Cs) exceeds 0% and 20%. It is preferably 0.0% or less. By containing the Rn ₂ O component, the meltability of the glass can be improved. Further, by making the amount of this substance less than 20.0%, it is difficult to lower the refractive index of the glass, and the stability of the glass can be improved. Therefore, the total amount of the Rn ₂ O component content relative to the total amount of glass in the oxide equivalent composition is preferably more than 0%, more preferably 1.0%, and most preferably 2.0%. The upper limit is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%.

The MgO component is a component that enhances the meltability of the glass, and is an optional component in the optical glass of the present invention. In particular, when the content of the MgO component is 20.0% or less, the refractive index of the glass is hardly lowered and the stability of the glass can be improved. Therefore, the content of the MgO component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%. The MgO component can be contained in the glass using, for example, MgCO ₃ or MgF ₂ as a raw material.

A CaO component is a component which improves the meltability of glass and adjusts the refractive index and dispersion | distribution of glass, and is an arbitrary component in the optical glass of this invention. In particular, when the content of the CaO component is 20.0% or less, the refractive index of the glass is hardly lowered and the stability of the glass can be improved. Therefore, the upper limit of the CaO component content with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%. The CaO component can be contained in the glass using, for example, CaCO ₃ , CaF ₂ or the like as a raw material.

A SrO component is a component which improves the meltability of glass, and is an arbitrary component in the optical glass of this invention. In particular, when the content of the SrO component is 20.0% or less, the refractive index of the glass is hardly lowered and the stability of the glass can be improved. Therefore, the upper limit of the content of the SrO component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%. The SrO component can be contained in the glass using, for example, Sr (NO ₃ ) ₂ , SrF ₂ or the like as a raw material.

A BaO component is a component which raises the refractive index of glass, and is an arbitrary component in the optical glass of this invention. In particular, the stability of glass can be improved by making the content rate of a BaO component 20.0% or less. Therefore, the upper limit of the content of the BaO component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%. The BaO component can be contained in the glass using, for example, BaCO ₃ , Ba (NO ₃ ) ₂ or the like as a raw material.

  In the optical glass of the present invention, the content amount of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is 1.0% or more and 25.0. % Or less is preferable. In particular, the refractive index of glass can be raised by containing RO component 1.0% or more. On the other hand, the stability of glass can be improved by making this sum of substance amounts 25.0% or less. Therefore, the total amount of the RO component content relative to the total amount of glass in the oxide conversion composition is preferably 1.0%, more preferably 3.0%, and most preferably 4.0% as the lower limit. Is 25.0%, more preferably 22.0%, and most preferably 20.0%.

The TeO ₂ component is a component that lowers the glass transition point and increases the refractive index of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content ratio of the TeO ₂ component to 10.0% or less, the thermal expansion coefficient of the glass can be reduced, and alloying with the platinum member can be suppressed. Therefore, the content of the TeO ₂ component with respect to the total amount of glass in the oxide conversion composition is preferably 10.0%, more preferably 7.0%, and most preferably 5.0%. The TeO ₂ component can be contained in the glass using, for example, TeO ₂ as a raw material.

ZrO ₂ component is a component that raises the refractive index of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of the ZrO ₂ component to 15.0% or less, it is possible to increase the stability of the glass and make it difficult to increase the liquidus temperature of the glass. Therefore, the content of the ZrO ₂ component with respect to the total amount of glass in the oxide conversion composition is preferably 15.0%, more preferably 12.0%, and most preferably 10.0%. The ZrO ₂ component can be contained in the glass using, for example, ZrO ₂ , ZrF ₄ or the like as a raw material.

Ta ₂ O ₅ component is a component that raises the refractive index of the glass, an optional component of the optical glass of the present invention. In particular, the glass can be stabilized by setting the content of the Ta ₂ O ₅ component to 20.0% or less. Therefore, the content of the Ta ₂ O ₅ component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%. The Ta ₂ O ₅ component can be contained in the glass using, for example, Ta ₂ O ₅ as a raw material.

The WO ₃ component is a component that lowers the glass transition point (Tg), improves the stability of the glass, and increases the refractive index of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the WO ₃ component to 20.0% or less, the phase separation tendency of the glass can be reduced. Therefore, the content of the WO ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%. The WO ₃ component can be contained in the glass using, for example, WO ₃ as a raw material.

Y ₂ O ₃ component increases the refractive index of the glass is a component to lower the dispersion of the glass, an optional component of the optical glass of the present invention. In _particular, by setting the content of Y 2 _{O 3} component to 10.0% or less, it is possible to increase the stability of the glass. Therefore, the content of the Y ₂ O ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 10.0%, more preferably 7.0%, and most preferably 5.0%. The Y ₂ O ₃ component can be contained in the glass using, for example, Y ₂ O ₃ , YF ₃ or the like as a raw material.

Gd ₂ O ₃ component increases the refractive index of the glass is a component to lower the dispersion of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of _Gd 2 _{O 3} component below 15.0%, it is possible to increase the stability of the glass. Therefore, the content of the Gd ₂ O ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 15.0%, more preferably 12.0%, and most preferably 10.0%. The Gd ₂ O ₃ component can be contained in the glass using, for example, Gd ₂ O ₃ , GdF ₃ or the like as a raw material.

Yb ₂ O ₃ component increases the refractive index of the glass is a component to lower the dispersion of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of _Yb 2 _{O 3} component below 20.0%, it is possible to increase the stability of the glass. Therefore, the content of the Yb ₂ O ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%. The Yb ₂ O ₃ component can be contained in the glass using, for example, Yb ₂ O ₃ as a raw material.

The Sb ₂ O ₃ component is a component that facilitates defoaming of the glass to easily obtain a clear glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of _Sb 2 _{O 3} ingredient 1.0% or less, can be hardly caused excessive foaming during glass melting, _Sb 2 _{O 3} ingredient is dissolved facilities (especially noble metal such as Pt ) And alloying can be made difficult. Therefore, the content of the Sb ₂ O ₃ component with respect to the total glass mass of the oxide-converted composition is preferably 1.0%, more preferably 0.9%, and most preferably 0.8%. The Sb ₂ O ₃ component can be contained in the glass using, for example, Sb ₂ O ₃ , Sb ₂ O ₅ , Na ₂ H ₂ Sb ₂ O ₇ · 5H ₂ O, or the like as a raw material.

Incidentally, components defoamed fining glass is not limited to the above Sb ₂ O ₃ component, a known refining agents in the field of glass production, it is possible to use a defoamer or a combination thereof.

<About ingredients that should not be included>
Next, components that should not be contained in the optical glass of the present invention and components that are not preferably contained will be described.

  Other components can be added as needed within a range not impairing the properties of the glass of the present invention. However, the transition metal components such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag and Mo, excluding Ti, are colored in the visible region even when they are contained individually or in combination and in small amounts. In particular, in an optical glass using a wavelength in the visible region, it is preferably substantially not contained.

Furthermore, lead compounds such as PbO, arsenic compounds such as As ₂ O ₃ , and components of Th, Cd, Tl, Os, Be, and Se have been refraining from being used as harmful chemical substances in recent years. Environmental measures are required not only in the manufacturing process but also in the processing process and disposal after commercialization. Therefore, when importance is placed on the environmental impact, it is preferable not to substantially contain them except for inevitable mixing. As a result, the optical glass is substantially free of substances that pollute the environment. Therefore, the optical glass can be manufactured, processed, and discarded without taking any special environmental measures.

The glass composition of the present invention is not expressed directly in terms of mass% because the composition is expressed in terms of mol% with respect to the total amount of glass in the oxide-converted composition, but is required in the present invention. The composition represented by mass% of each component present in the glass composition satisfying the characteristics generally takes the following values in terms of oxide conversion.
B ₂ O ₃ component 3.0 to 30.0% by weight and TiO ₂ component 3.0 to 30.0% by weight and ZnO component from 0.7 to 30.0 wt% and _La 2 _{O 3} component from 15.0 to 55 .0 mass%
And SiO ₂ component 0 to 7.0 mass% and / or Nb ₂ O ₅ component 0 to 45.0 mass% and / or P ₂ O ₅ component 0 to 5.0 mass% and / or GeO ₂ component 0 to 10 0.0% by mass and / or Al ₂ O ₃ component 0-10.0% by mass and / or Li ₂ O component 0-7.0% by mass and / or Na ₂ O component 0-15.0% by mass and / or K ₂ O component 0 to 20.0% by weight and / or Cs ₂ O component from 0 to 50.0% by weight and / or MgO component from 0 to 8.0 wt% and / or CaO component 0 to 10.0% by weight and / or SrO component 0 to 20.0% by weight and / or BaO components from 0 to 30.0% by weight and / or TeO ₂ component from 0 to 15.0% by weight and / or ZrO ₂ component from 0 to 17.0% by weight and / or _Ta 2 _{O 5} component from 0 to 50.0% by weight and / or WO Components from 0 to 45.0% by weight and / or _Y 2 _{O 3} component 0 to 20.0% by weight and / or _Gd 2 _{O 3} component from 0 to 50.0% by weight and / or _Yb 2 _{O 3} component 0-50. 0 wt% and / or _Sb 2 _{O 3} component 0-3.0 wt%

[Production method]
The optical glass of the present invention is produced, for example, as follows. That is, the above raw materials are uniformly mixed so that each component is within a predetermined content range, and the prepared mixture is put into a quartz crucible or an alumina crucible and roughly melted, and then a gold crucible, a platinum crucible, a platinum alloy It is prepared by putting in a crucible or iridium crucible, melting in a temperature range of 700 to 1200 ° C., stirring and homogenizing, blowing out bubbles, etc., then lowering to an appropriate temperature, casting into a mold and slow cooling. .

[Physical properties]
The optical glass of the present invention needs to have a high refractive index (n _d ) and moderate dispersibility. In particular, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.75, more preferably 1.78, most preferably 1.80, and preferably 2.20, more preferably 2.80. 18, most preferably 2.15. Further, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 21.0, more preferably 22.0, and most preferably 23.0, preferably 40.0, more preferably 39. The upper limit is 0, most preferably 38.0. As a result, the degree of freedom in optical design is increased, and a large amount of light refraction can be obtained even if the device is made thinner.

  Further, the optical glass of the present invention needs to be softened at the lowest possible temperature. In particular, the upper limit of the glass transition point (Tg) of the optical glass of the present invention is preferably 620 ° C., more preferably 600 ° C., and most preferably 580 ° C. Thereby, even if a preform material such as a precision press-molding preform is produced from the optical glass of the present invention and this is heated and softened to produce an optical element, the glass can be softened at a low temperature.

  Moreover, the optical glass of the present invention needs to be as easy to press-mold as possible. In particular, the upper limit of the yield point (At) of the optical glass of the present invention is preferably 640 ° C, more preferably 630 ° C, and most preferably 620 ° C. Like the glass transition point (Tg), the yield point (At) is one of the indices indicating the low temperature softening property of the glass, but is an index indicating a temperature closer to the press molding temperature. Therefore, in a glass having a low yield point (At), the press molding temperature can be further lowered, and such glass can be easily press molded.

  The optical glass of the present invention has high thermal stability. In particular, the difference ΔT between the glass transition point (Tg) and the crystallization start temperature (Tx) is preferably 150 ° C., more preferably 153 ° C., and most preferably 155 ° C. As a result, the thermal stability of the glass can be enhanced, so that a preform material such as a precision press-molding preform is produced using the optical glass of the present invention, and this is heated and softened and molded to produce an optical element. Even if manufactured, the influence on the optical characteristics of the optical element, such as devitrification of the optical element due to crystallization of heat-softened glass, can be reduced.

[Preforms and optical elements]
The optical glass of the present invention is useful for various optical elements and optical designs. In particular, it is possible to produce an optical element such as a lens from the optical glass of the present invention using means such as precision press molding. preferable. As a result, when used in an optical device such as a camera, it is possible to reduce the size of the optical system in these optical devices while realizing high-definition and high-precision imaging characteristics. Here, in order to produce an optical element made of the optical glass of the present invention, it is possible to omit cutting and polishing, so that glass in a molten state is dropped from the outlet of an outflow pipe such as platinum to form a spherical shape. It is preferable to prepare a precision press-molding preform such as, and perform precision press-molding on the precision press-molding preform.

Composition of Examples (No. 1 to No. 4) and Reference Example (No. 1) of the present invention, and the refractive index (n _d ), Abbe number (ν _d ), and glass transition point (Tg) of these glasses. ), Crystallization start temperature (Tx), yield point (At), and glass transition point and crystallization start temperature difference (ΔT) are shown in Table 1. The following examples are merely for illustrative purposes, and are not limited to these examples.

  The optical glass of Examples (No. 1 to No. 4) of the present invention and the glass of Reference Example (No. 1) are all oxides, hydroxides, carbonates and nitrates corresponding to the raw materials of the respective components. Select high-purity raw materials used in ordinary optical glass, such as fluoride, hydroxide, and metaphosphoric acid compounds, and weigh and uniformly mix to the proportions of the compositions shown in Table 1 Then, it is put into a quartz crucible or a platinum crucible, melted in a temperature range of 700 to 1200 ° C. in an electric furnace according to the melting difficulty of the glass composition, homogenized with stirring, cast into a mold, and slowly cooled to glass. Was made.

Here, the refractive index (n _d ) and Abbe number (ν _d ) of the optical glass of the example (No. 1 to No. 4) and the glass of the reference example (No. 1) are set to -25. It calculated | required by measuring about the glass obtained by setting it at (degreeC / h).

  Moreover, the glass transition point (Tg) and the buckling point (At) of the optical glass of the example (No. 1 to No. 4) and the glass of the reference example (No. 1) are the differential heat measuring apparatus (STAC manufactured by Netchigerebau) 409 CD). The sample particle size at this time was set to 425-600 micrometers, and the temperature increase rate was 10 degrees C / min. Furthermore, ΔT of the optical glass of the example (No. 1 to No. 4) and the glass of the reference example (No. 1), the glass transition point (Tg) obtained by this method, and the crystallization start temperature (Tx). And obtained from the difference.

  As shown in Table 1, all of the optical glasses of the examples of the present invention had a glass transition point (Tg) of 620 ° C. or lower, more specifically 580 ° C. or lower. In particular, the optical glasses of Examples (No. 3 and No. 4) have a glass transition point (Tg) of 560 ° C. or lower, and have a glass transition point (Tg) lower than that of Reference Example (No. 1). It became clear that it was easy to soften at a low temperature.

  In addition, as shown in Table 1, all the optical glasses of the examples of the present invention had a yield point (At) of 640 ° C. or lower, more specifically 615 ° C. or lower. On the other hand, the glass of the reference example had a yield point (At) higher than 615 ° C. For this reason, it became clear that the optical glass of the Example of this invention is easy to press-mold compared with the glass of a reference example.

  Further, as shown in Table 1, the optical glasses of the examples of the present invention all have a difference ΔT between the glass transition point (Tg) and the crystallization start temperature (Tx) of 150 ° C. or more, more specifically It was 157 ° C or higher. On the other hand, the glass of the reference example had a ΔT of less than 157 ° C. For this reason, it became clear that the optical glass of the Example of this invention has high thermal stability compared with the glass of a reference example.

The optical glasses of the examples of the present invention all have a refractive index (n _d ) of 1.75 or more, more specifically 1.80 or more, and this refractive index (n _d ) of 2.20 or less. More specifically, it was 2.15 or less, and was within the desired range.

The optical glasses of the examples of the present invention all have an Abbe number (ν _d ) of 21.0 or more, more specifically 23.0 or more, and this Abbe number (ν _d ) is 40 or less. Specifically, it was 38.0 or less, which was within the desired range.

Therefore, the optical glass of the example of the present invention is easily softened at a low temperature, easily press-molded, and has a high heat resistance while its refractive index (n _d ) and Abbe number (ν _d ) are within the desired ranges. It became clear that it has mechanical stability.

  Furthermore, when a precision press-molding preform was formed using the optical glass of the embodiment of the present invention, and the precision press-molding preform was precision press-molded, it could be stably processed into various lens shapes. .

  Although the present invention has been described in detail for the purpose of illustration, this embodiment is only for the purpose of illustration, and many modifications can be made by those skilled in the art without departing from the spirit and scope of the present invention. Will be understood.

Claims (16)

The glass the total amount of substance of the oxide composition in terms of, 5.0 to 50.0% of _B 2 _{O 3} component in mol%, the TiO ₂ component from 5.0 to 40.0%, the ZnO component 1.0 Optical glass containing ˜40.0% and 5.0 to 20.0% La ₂ O ₃ component. SiO ₂ component 0 to 10.0% and / or Nb ₂ O ₅ component 0 to 20.0% in mol% with respect to the total amount of glass of oxide-converted composition
The optical glass according to claim 1, further comprising: The glass the total amount of substance of the oxide composition in terms of, 0~5.0% _P 2 _{O 5} component in mol% and / or GeO ₂ component from 0 to 10.0% and / or _Al 2 _{O 3} component 0 .0%
The optical glass according to claim 1, further comprising: 4. The optical glass according to claim 3, wherein the ratio of the substance amount of the oxide equivalent composition (B ₂ O ₃ + P ₂ O ₅ ) / (SiO ₂ + GeO ₂ + Al ₂ O ₃ ) is 6.0 or more. Li ₂ O component 0-20.0% and / or Na ₂ O component 0-20.0% and / or K ₂ O component 0-20. 0% and / or Cs ₂ O component from 0 to 20.0%
The optical glass according to claim 1, further comprising: 6. The optical glass according to claim 5, wherein the total amount of substances Li ₂ O + Na ₂ O + K ₂ O + Cs ₂ O with respect to the total amount of glass having an oxide equivalent composition exceeds 0% and is 20.0% or less. MgO component 0 to 20.0% and / or CaO component 0 to 20.0% and / or SrO component 0 to 20.0% and / or BaO in mol% with respect to the total amount of glass in the oxide conversion composition Ingredient 0-20.0%
The optical glass according to claim 1, further comprising:   8. The optical glass according to claim 7, wherein the total amount of MgO + CaO + SrO + BaO + ZnO with respect to the total amount of glass having an oxide conversion composition is 1.0% to 25.0%. TeO ₂ component 0 to 10.0% and / or ZrO ₂ component 0 to 15.0% and / or Ta ₂ O ₅ component 0 to 20.0 in mol% with respect to the total amount of glass in the oxide conversion composition % and / or WO ₃ components from 0 to 20.0% and / or _Y 2 _{O 3} component from 0 to 10.0% and / or _Gd 2 _{O 3} component from 0 to 15.0% and / or _Yb 2 _{O 3} component 0 20.0% and / or _Sb 2 _{O 3} component from 0 to 1.0%
The optical glass according to claim 1, further comprising: The optical glass according to claim 1, which has a refractive index (n _d ) of 1.75 or more and 2.20 or less and an Abbe number (ν _d ) of 21.0 or more and 40.0 or less.   The optical glass according to claim 1, which has a glass transition point (Tg) of 620 ° C. or lower.   The optical glass according to any one of claims 1 to 11, wherein a bending point (At) is 640 ° C or lower.   The optical element which uses the optical glass in any one of Claims 1-12 as a base material.   An optical element produced by precision press molding the optical glass according to claim 1.   A precision press-molding preform made of the optical glass according to claim 1.   An optical element produced by precision press-molding the precision press-molding preform according to claim 15.