JP2013087009A - Optical glass, preform and optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide optical glass having high transparency with respect to a visible region, hardly generating devitrification or cloudiness in manufacture or processing of glass, and allowing easy manufacturing of a preform material or an optical element by polishing, and to provide a preform using the optical glass.SOLUTION: This optical glass includes, in terms of mass% to the whole mass of glass having a composition in terms of oxides, a ≥70.0% to ≤90.0% BiOcomponent, a ≥6.0% to ≤20.0% BOcomponent, and a >0% to ≤20% SiOcomponent, respectively.

Description

  The present invention relates to an optical glass, a 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, it has a desired high refractive index (n _d ) and Abbe number (ν _d ) capable of reducing the weight and size of the optical element, and has a high refractive index and a high refractive index. There is a great demand for glass with dispersion.

  For the production of such optical elements, a method of grinding and polishing molded glass obtained by heat softening a glass material and press molding (reheat press molding), or a preform obtained by cutting and grinding and polishing a gob or glass block A method (precise press molding) is used in which a material or a foam material molded by known flotation molding is heated and softened and press molded with a mold having a highly accurate molding surface.

  In addition, since the optical glass having a high partial dispersion ratio (θg, F) has a lower transparency to visible light as the Abbe number (νd) is lower (λ70 is larger), it is colored yellow or orange and visible. It is not suitable for applications that transmit light in a region.

  On the other hand, Patent Documents 1 to 3 describe optical glasses having a desired Abbe number, partial dispersion ratio, and spectral transmittance.

JP 2011-42556 A JP 2011-93731 A JP 2009-149521 A

However, in the glasses disclosed in Patent Documents 1 to 3, the lower the Abbe number (ν _d ), the lower the transparency to visible light (the longer the value of λ ₇₀ ), and the lower the Abbe number (ν _d ). Is colored yellow or orange. Therefore, the glasses disclosed in Patent Documents 1 to 3 are not suitable for applications that transmit light in the visible region even if they have a desired refractive index and high dispersion. Further, the optical glasses disclosed in Patent Documents 1 to 3 have a problem that devitrification is likely to occur when the glass is produced. Furthermore, the glass that is free from devitrification when the glass is produced tends to become cloudy when the glass press-molded by reheat press is polished or when the preform is produced by polishing the glass. There was a problem. It has been difficult to produce an optical element that can control light in the visible region from glass once devitrified or cloudy. Further, the colored glass is not suitable as a material for the optical element because the light transmittance at a wavelength in the visible range is lowered.

The present invention has been made in view of the above problems, Bi ₂ O ₃ content of the component, B ₂ O ₃ to the content of the content and the content of SiO ₂ of component within a predetermined range Although having a high refractive index (n _d ), a low partial dispersion ratio (θg, F), and an Abbe number (νd) within a desired range, the spectral transmittance (5%) and the spectral transmittance (70% ) Has a wavelength on the short wavelength side, has high transparency in the visible region, and is less susceptible to devitrification and fogging during glass production and processing, making it easy to produce preform materials and optical elements by polishing. The object is to provide glass and a preform using the same.

As a result of intensive studies and studies to solve the above problems, the present inventor has determined that the content of the Bi ₂ O ₃ component, the content of the B ₂ O ₃ component, and the content of the SiO ₂ component are within a predetermined range. As a result, the spectral transmittance (5%) and the spectral transmittance (with the refractive index (n _d ), partial dispersion ratio (θg, F), and Abbe number (νd) of the optical glass within the desired ranges are obtained. 70%) was found on the short wavelength side, and the present invention was completed.

In the optical glass according to the embodiment of the present invention, the Bi ₂ O ₃ component is 70.0% or more and 90.0% or less and the B ₂ O ₃ component is 6.0% by mass% with respect to the total mass of the glass in terms of the oxide. More than 20.0% and SiO ₂ component is contained more than 0% and 20% or less, respectively.

In the optical glass, the Bi ₂ O ₃ component, the B ₂ O ₃ component, and the SiO ₂ component may be contained in a total of 90.0% or more by mass% with respect to the total mass of the glass in terms of oxide.

In the optical glass, the Bi ₂ O ₃ component, the Nb ₂ O ₅ component, and the ZrO ₂ component may be contained in a total of 70.0% or more by mass% with respect to the total mass of the glass in terms of the oxide.

  In the optical glass, any one or more of MgO component, CaO component, SrO component, BaO component, and ZnO component may be contained in excess of 0% by mass% with respect to the total glass mass of the oxide equivalent composition.

In the optical glass, the Li ₂ O component is 0 to 8.0%, the Na ₂ O component is 0 to 8.0%, and the K ₂ O component is 0 to 8.0% by mass% with respect to the total mass of the oxide-converted composition. , Al ₂ O ₃ component 0 to 10.0%, ZrO ₂ component 0 to 10.0%, Ta ₂ O ₅ component 0 to 10.0%, WO ₃ component 0 to 10.0%, La ₂ O ₃ component 0 to 10.0%, Gd ₂ O ₃ component 0 to 10.0%, Y ₂ O ₃ component 0 to 10.0%, Yb ₂ O ₃ component 0 to 10.0%, P ₂ O ₅ component 0 10.0%, further may contain _Sb 2 _{O 3} each of component 0 to 5.0%.

In the optical glass, a TeO ₂ component may be contained in an amount of 0% or more and 5% or less by mass% with respect to the total mass of the glass in terms of oxide.

In the optical glass, a wavelength (λ ₅ ) showing a spectral transmittance (5%) in a sample having a thickness of 10 mm is 350 nm to 450 nm and a wavelength (λ ₇₀ ) showing a spectral transmittance (70%) in a sample having a thickness of 10 mm. ) May be 380 nm or more and 500 nm or less.

  In the optical glass, the partial dispersion ratio (θg, F) may be 0.63 or more and 0.67 or less.

In the optical glass, the refractive index (n _d ) may be 1.95 or more, and the Abbe number (ν _d ) may be 15 or more and 25 or less.

  A precision press-molding preform according to an embodiment of the present invention is characterized by comprising the optical glass described in any one of the above.

  An optical element according to an embodiment of the present invention includes the optical glass according to any one of the above.

  In the optical element, the preform may be molded by precision pressing.

According to the present invention, by setting the content of the Bi ₂ O ₃ component, the content of the B ₂ O ₃ component, and the content of the SiO ₂ component within predetermined ranges, the desired refractive index ( _{nd )} ), A low partial dispersion ratio (θg, F) and an Abbe number (ν _d ) within a desired range, but the spectral transmittance (5%) and spectral transmittance (70%) are on the short wavelength side. And optical glass having high transparency in the visible region, hardly causing devitrification and fogging during the production and processing of the glass, and capable of easily producing a preform material and an optical element by polishing processing, and the like. A preform can be provided.

In the optical glass which concerns on the Example and comparative example of this invention, it is a figure which shows the relationship between a refractive index ( _nd ) and spectral transmittance (5%). In the optical glass which concerns on the Example and comparative example of this invention, it is a figure which shows the relationship between a refractive index ( _nd ) and spectral transmittance (70%). In the optical glass which concerns on the Example and comparative example of this invention, it is a figure which shows the relationship between refractive index ( _nd ) and Abbe number ((nu) _d ). In the optical glass which concerns on the Example and comparative example of this invention, it is a figure which shows the relationship between partial dispersion ratio ((theta) g, f) and spectral transmittance (5%).

In the optical glass according to the embodiment of the present invention, the Bi ₂ O ₃ component is 70.0% or more and 90.0% or less and the B ₂ O ₃ component is 6.0% by mass% with respect to the total mass of the glass in terms of the oxide. by each containing 20.0% or less and the SiO ₂ component 0% and 20.0% less than a refractive index _{(n d)} of 1.95 or more, the partial dispersion ratio ([theta] g, F) is 0.63 or more Although the Abbe number (νd) is not less than 0.67 and the Abbe number (νd) is not less than 15 and not more than 25, the spectral transmittance (5%) may be 350 nm to 450 nm and the spectral transmittance (70%) may be 380 nm to 500 nm. it can. As a result, the spectral transmittance (5%) and the spectral transmittance (70%) have a wavelength on the short wavelength side, are highly transparent to the visible region, and are devitrified and cloudy during glass production and processing. It is difficult to provide an optical glass that is easy to produce a preform material or an optical element by polishing, and a preform using the optical glass.

  Hereinafter, embodiments of the present invention will be described in detail. In addition, this invention is not limited to the following embodiment, In the range which does not deviate from the summary, it can implement in a various aspect.

[Glass component]
The composition range of each component constituting the optical glass according to the embodiment of the present invention will be described below. Each component is expressed in terms of mass% with respect to the total mass of the oxide equivalent composition. Here, the “oxide standard” means that when the oxide, nitrate, etc. used as the raw material of the glass component according to the embodiment of the present invention are all decomposed and changed into oxides when melted, the generated oxidation It is the composition which described each component contained in glass by making the sum total of the mass of a thing into 100 mass%.

<About essential and optional components>
The SiO ₂ component is a component that improves the stability of the glass and reduces devitrification, and has the effect of reducing the dispersion of the glass, the transmittance, the scientific durability, the improvement of the degree of wear, and the viscosity with respect to the liquidus temperature. Is an essential component of the optical glass according to the embodiment of the present invention. However, when the content of the SiO ₂ component is too large, the refractive index (n _d ) and the partial dispersion ratio of the glass are likely to be lowered, and the meltability of the glass is likely to be deteriorated. Therefore, the content of the SiO ₂ component is mass% with respect to the total mass of the oxide conversion composition, preferably 20.0% or less, more preferably less than 10.0%, still more preferably 6.0% or less, most preferably Preferably, the upper limit is 3.0% or less. On the other hand, the content of the SiO ₂ component is mass% with respect to the total mass of the oxide conversion composition, and preferably exceeds 0%, more preferably 1.0%, and most preferably 1.5%. The SiO ₂ component can be contained in the glass using, for example, SiO ₂ as a raw material, and SiO ₂ can also be contained using a quartz glass crucible.

The B ₂ O ₃ component is an essential component that has the effect of improving the chemical durability by improving the stability of the glass to reduce devitrification and maintaining a high partial dispersion ratio of the glass. However, if the content of the B ₂ O ₃ component is too large, the stability of the glass tends to decrease, devitrification tends to occur, and the glass tends to have a low refractive index and low dispersion. Therefore, the content of the B ₂ O ₃ component is mass% with respect to the total mass of the oxide conversion composition, preferably 20.0%, more preferably 18.0%, and most preferably 17.0%. . On the other hand, the content of the B ₂ O ₃ component is mass% with respect to the total mass of the oxide conversion composition, preferably 6.0%, more preferably 7.0%, and most preferably 11.0%. . 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.

The Al ₂ O ₃ component is an optional component useful for improving the chemical durability and mechanical strength of the glass, improving the degree of wear, and increasing the viscosity with respect to the liquidus temperature. However, if the content of the Al ₂ O ₃ component is too large, the meltability of the glass tends to decrease, the devitrification property increases, and the glass yield point tends to increase. Accordingly, the content of the Al ₂ O ₃ component is mass% with respect to the total mass of the oxide-converted composition, preferably 10.0%, more preferably 9.0%, and most preferably 8.0%. . The Al ₂ O ₃ component can be contained in the glass using, for example, Al ₂ O ₃ , Al (OH) ₃ or the like as a raw material.

The Y ₂ O ₃ component is an optional component useful for lowering the glass and increasing the refractive index. However, if the content is too large, the glass stability tends to be lowered. Therefore, the upper limit of the content of the Y ₂ O ₃ component is preferably 10.0%, more preferably 9.0%, and most preferably 8.0%.

The La ₂ O ₃ component is an optional component useful for lowering the glass and increasing the refractive index. However, if the content is too large, the glass stability tends to be lowered. Therefore, the content of the La ₂ O ₃ component is preferably 10.0%, more preferably 9.0%, and most preferably 8.0%.

The Gd ₂ O ₃ component is an optional component useful for reducing the glass dispersion and increasing the refractive index. However, if the content is too large, the glass stability tends to be lowered. Accordingly, the content of the Gd ₂ O ₃ component is preferably 10.0%, more preferably 9.0%, and most preferably 8.0%.

The Yb ₂ O ₃ component is an optional component useful for lowering the glass and increasing the refractive index. However, if the content is too large, the glass stability tends to be lowered. Therefore, the content of the Yb ₂ O ₃ component is preferably 10.0%, more preferably 9.0%, and most preferably 8.0%.

Y ₂ O ₃ component, La ₂ O ₃ component, Gd ₂ O ₃ component and Yb ₂ O ₃ component are effective in improving the chemical durability of the glass and are components that can be optionally added. When there is much, there exists a tendency for dispersion | distribution to become low dispersion | distribution, and devitrification resistance tends to increase. However, when there is too much these content, stability of glass will fall and the transmittance | permeability with respect to the light of visible region will fall easily. Further, _Ln 2 _{O 3} component (wherein, Ln is Y, La, at least one selected from the group consisting of Gd and Yb) mass sum is the percentage by weight relative to the total weight of the oxide basis composition The upper limit is preferably 10.0%, more preferably 9.0%, and still more preferably 8.0%. Y ₂ O ₃ component, La ₂ O ₃ component, Gd ₂ O ₃ component and Yb ₂ O ₃ component of the glass component are, for example, La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ O (X is optional) Integer), Gd ₂ O ₃ , Y ₂ O ₃ , Yb ₂ O _{3 and the} like.

The TiO ₂ component is an effective optional component for increasing the refractive index (n _d ) and partial dispersion ratio of glass. However, when there is too much the content, stability of glass will fall and it will become easy to fall in the transmittance. Therefore, the content of the TiO ₂ component is mass% with respect to the total mass of the oxide conversion composition, preferably 10.0%, more preferably 9.0%, and most preferably 8.0%. TiO ₂ component may be contained in the glass by using as the starting material for example TiO ₂ or the like.

The ZrO ₂ component is an optional component useful for improving the chemical durability and mechanical strength of glass. However, if the content of the ZrO ₂ component is too large, the transmittance tends to decrease the stability of the glass is lowered. Therefore, the content of the ZrO ₂ component is mass% with respect to the total mass of the oxide conversion composition, preferably 10.0%, more preferably 5.0%, and most preferably 1.0%. On the other hand, the content of the ZrO ₂ component is mass% with respect to the total mass of the oxide-converted composition, preferably 0%, more preferably 0.2%, and most preferably 0.3%. The ZrO ₂ component can be contained in the glass using, for example, ZrO ₂ as a raw material.

The Nb ₂ O ₅ component is an essential component useful for improving the refractive index (n _d ) of glass, improving the partial dispersion ratio, and improving the devitrification property of glass. However, when the content of Nb ₂ O ₅ component is too large, the transmittance tends to decrease the stability of the glass is lowered. Therefore, the content of the Nb ₂ O ₅ component is mass% with respect to the total mass of the oxide conversion composition, preferably 10.0%, more preferably 5.0%, and most preferably 0.6%. . On the other hand, the content of the Nb ₂ O ₅ component is mass% with respect to the total mass of the oxide conversion composition, preferably 0%, more preferably 0.1%, and most preferably 0.2%. The Nb ₂ O ₅ component can be contained in the glass using, for example, Nb ₂ O ₅ as a raw material.

The Ta ₂ O ₅ component is an optional component useful for increasing the refractive index (n _d ) of the glass and improving the stability of the glass. However, when the content of Ta ₂ O ₅ component is too much, it tends to decrease. Transmittance stability of the glass is lowered, and the raw material cost of the glass is significantly increased. Therefore, the content of the Ta ₂ O ₅ component is mass% with respect to the total mass of the oxide conversion composition, preferably 10.0%, more preferably 9.0%, and most preferably 8.0%. . 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 an optional component useful for increasing the refractive index (n _d ) of the glass, improving the partial dispersion ratio of the glass, and reducing the Tg (glass transition point). However, when there is too much the content, stability of glass will fall and it will become easy to fall in the transmittance. Therefore, the content of the WO ₃ component is mass% with respect to the total mass of the oxide-converted composition, preferably 10.0%, more preferably 9.0%, and most preferably 8.0%. The WO ₃ component can be contained in the glass using, for example, WO ₃ as a raw material.

The ZnO component is an essential component useful for improving the chemical durability and devitrification resistance of glass. However, if the content is too large, it becomes difficult to obtain a desired partial dispersion ratio and Abbe number (ν _d ). Therefore, the upper limit of the content of the ZnO component is preferably 10.0%, more preferably 5.0%, and most preferably 2.0%. Further, although it is possible to produce an optical glass having desired optical characteristics in the embodiment of the present invention without containing a ZnO component, it is easy to adjust the partial dispersion ratio and Abbe number (ν _d ) described later. For this purpose, the ZnO component is preferably contained with a lower limit of more than 0%, more preferably 0.5%, and most preferably 0.9%.

The MgO component is an optional component useful for increasing the dispersion of glass and improving devitrification resistance. However, when there is too much content of a MgO component, stability of glass and the transmittance | permeability of visible light will fall easily, and it will become easy to devitrify by the reheating process at the time of press molding. Therefore, the content of the MgO component is mass% with respect to the total mass of the oxide-converted composition, preferably 10.0%, more preferably 9.0%, and most preferably 8.0%. The MgO component can be contained in the glass using, for example, MgO, MgCO ₃ or the like as a raw material.

The CaO component is an optional component useful for improving transmittance, glass low dispersion, devitrification resistance, and chemical durability. However, when there is too much content of a CaO component, the devitrification resistance of glass will fall easily. Therefore, the content of the CaO component is mass% with respect to the total mass of the oxide-converted composition, preferably 5.0%, more preferably 2.0%, and most preferably 0.5%. On the other hand, the content of the CaO component is mass% with respect to the total mass of the oxide-converted composition, and preferably exceeds 0%, more preferably 0.1%, and most preferably 0.2%. The CaO component can be contained in the glass using, for example, CaCO ₃ as a raw material.

The SrO component is a component useful for improving the devitrification resistance of the glass. However, when there is too much content of a SrO component, devitrification resistance will fall easily. Moreover, it becomes difficult to obtain a desired partial dispersion ratio and Abbe number (ν _d ). Therefore, the content of the SrO component is mass% with respect to the total mass of the oxide-converted composition, preferably 5.0%, more preferably 2.0%, and most preferably 0.6%. On the other hand, the content of the SrO component is mass% with respect to the total mass of the oxide conversion composition, and preferably exceeds 0%, more preferably 0.1%, and most preferably 0.2%. The SrO component can be contained in the glass using, for example, Sr (NO ₃ ) ₂ as a raw material.

The BaO component is an optional component useful for improving the devitrification resistance of glass. However, if the content of the BaO component is too large, it becomes difficult to obtain the refractive index (n _d ) of the glass, and it becomes difficult to obtain the desired partial dispersion ratio and Abbe number (ν _d ). Therefore, the content of the BaO component is mass% with respect to the total mass of the oxide conversion composition, preferably 5.0%, more preferably 3.0%, and most preferably 1.5%. On the other hand, the content of the BaO component is mass% with respect to the total mass of the oxide-converted composition, and preferably exceeds 0%, more preferably 0.1%, and most preferably 0.2%. 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 according to the embodiment of the present invention, the RO component (R is one or more selected from Mg, Ca, Sr and Ba) is devitrification resistance, dispersion, mechanical strength, liquid phase of the glass. It is a useful component for adjusting all physical properties such as viscosity with respect to temperature. However, if the total content of RO components is too large, it becomes difficult to obtain a desired partial dispersion ratio and Abbe number (ν _d ). Therefore, the total content of the RO component is mass% with respect to the total mass of the oxide-converted composition, preferably less than 10.0%, more preferably 5.0%, and most preferably 3.0%. On the other hand, an optical glass having the desired characteristics in the embodiment of the present invention can be produced without containing the RO component, but it contains at least one of the RO components while increasing the devitrification resistance of the glass. It is possible to easily adjust the partial dispersion ratio and Abbe number (ν _d ) of the glass and lower the viscosity with respect to the liquidus temperature. The total content of the RO component is mass% with respect to the total mass of the oxide-converted composition, and preferably exceeds 0%, more preferably 0.1%, and most preferably 0.2%.

Li 2 _O component is a component for reducing the devitrification to improve the stability of the glass, which is an optional component that and is effective to lower Tg of the glass. However, when the content of the Li ₂ O component is too large, the stability of the glass tends to be lowered, it becomes difficult to obtain a high refractive index (n _d ), the partial dispersion ratio is low, and the mechanical strength is likely to be lowered. Become. Therefore, the content of the Li ₂ O component is mass% with respect to the total mass of the oxide conversion composition, preferably 8.0%, more preferably 7.0%, and most preferably 5.0%. The Li ₂ O component can be contained in the glass using, for example, Li ₂ CO ₃ , LiNO ₃ or the like as a raw material.

The Na ₂ O component is an optional component that improves glass devitrification, adjusts the partial dispersion ratio and Abbe number (ν _d ) of the glass, and is effective in reducing the glass Tg. However, when the content of the Na ₂ O component is too large, the refractive index (n _d ) of the glass is lowered, the stability of the glass is liable to be lowered, and the chemical durability and mechanical strength of the glass are also liable to be lowered. . Therefore, the content of the Na ₂ O component is mass% with respect to the total mass of the oxide-converted composition, preferably 8.0%, more preferably 5.0%, and most preferably 1.0%. On the other hand, the content of the Na ₂ O component is mass% with respect to the total mass of the oxide-converted composition, and preferably exceeds 0%, more preferably 0.002%, and most preferably 0.003%. The Na ₂ O component can be contained in the glass using, for example, Na ₂ CO ₃ or NaNO ₃ as a raw material.

The K ₂ O component is an optional component that improves glass devitrification, adjusts the partial dispersion ratio and Abbe number (ν _d ) of the glass, and is effective in reducing Tg of the glass. However, when the content of K 2 _O component is too much, it tends to decrease. Stability of the glass, the chemical durability and mechanical strength of the glass becomes liable to lower. Therefore, the content of the K ₂ O component is mass% with respect to the total mass of the oxide-converted composition, preferably 8.0%, more preferably 7.0%, and most preferably 5.0%. The K ₂ O component can be contained in the glass using, for example, K ₂ CO ₃ , KNO ₃ or the like as a raw material.

In the optical glass according to the embodiment of the present invention, the mass sum of the contents of the Rn ₂ O component (Rn is one or more selected from Li, Na and K) may be 5.0% or less. preferable. By adjusting the mass sum to 5.0% or less, the stability of the glass can be further increased and the decrease in transmittance can be suppressed while adjusting the Abbe number (ν _d ) of the glass to a desired range. In particular, by setting the mass sum of the Rn ₂ O component to 1.0% or less, a decrease in the partial dispersion ratio is suppressed, so that a desired high partial dispersion ratio can be obtained more easily. Therefore, the content of the Rn ₂ O component (Rn is one or more selected from Li, Na and K) is preferably 5.0%, more preferably 3.0%, most preferably 1.0. % Is the upper limit.

The RO component and the Rn ₂ O component are effective in improving the meltability and stability of the glass and lowering the Tg, and further play a large role in improving the glass transparency in the visible range. Is indispensable. If the content of one or two of these components is too small, the effect is not observed, and if it is too large, the liquidus temperature rises and the glass stability deteriorates. Therefore, the total content of the RO and Rn ₂ O components is preferably more than 0%, more preferably 0.1%, and most preferably 0.2%. On the other hand, the total content of the RO and Rn ₂ O components is preferably 10.0%, more preferably 9.0%, and most preferably 8.0%.

The Sb ₂ O ₃ component is an optional component that has an effect of promoting clarification of glass. However, when there is too much the content, a meltability deterioration, the transmittance | permeability of glass, and devitrification resistance will fall. Therefore, the content of the Sb ₂ O ₃ component is mass% with respect to the total mass of the oxide-converted composition, preferably 5.0%, more preferably 3.0%, and most preferably 0.1%. . On the other hand, the content of the Sb ₂ O ₃ component is mass% with respect to the total mass of the oxide-converted composition, preferably 0%, more preferably 0.002%, and most preferably 0.005%. 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 of the fining defoaming of glass is not limited to the above Sb ₂ O ₃ ingredients may be used known refining agents and defoamers in the field of glass production, or a combination thereof .

The P ₂ O ₅ component is effective for improving the coloring of the glass and is an optional component useful for improving the transmittance of the glass. However, when the content of P ₂ O ₅ component is too large, the melting property of the glass tends to decrease. Therefore, the content of the P ₂ O ₅ component is mass% with respect to the total mass of the oxide-converted composition, preferably 10.0%, more preferably 9.0%, and most preferably 8.0%. . The P ₂ O ₅ component contains, for example, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , Na (PO ₃ ), BPO ₄ , H ₃ PO _{4, and the} like as raw materials. It can contain.

The Bi ₂ O ₃ component is an essential component that increases the refractive index (n _d ) of the glass, increases the partial dispersion ratio of the glass, and is effective for achieving high dispersion of the glass. In addition, it is a component that is also effective for lowering Tg and improving water resistance, and is an indispensable component for the optical glass according to the embodiment of the present invention. Here, by making the content of the Bi ₂ O ₃ component 70.0% or more, an optical glass having a desired high refractive index (n _d ) can be easily obtained. Therefore, the content of the Bi ₂ O ₃ component is mass% with respect to the total mass of the oxide-converted composition, preferably 70.0%, more preferably 71.0%, and most preferably 73.0%. . On the other hand, the content of the Bi ₂ O ₃ component is mass% with respect to the total mass of the oxide conversion composition, preferably 90.0%, more preferably 89.0%, and most preferably 87.0%. Thereby, since the stability of glass is improved, coloring of glass can be reduced. The Bi ₂ O ₃ component can be contained in the glass using, for example, Bi ₂ O ₃ as a raw material.

By using the Bi ₂ O ₃ component, the Nb ₂ O ₅ component, and the ZrO ₂ component together, it contributes to the stabilization of the glass while maintaining a high transmittance, and can further increase the partial dispersion ratio. Therefore, the total content of the Bi ₂ O ₃ component, the Nb ₂ O ₅ component, and the ZrO ₂ component is mass% with respect to the total mass of the oxide equivalent composition, preferably 70.0%, more preferably 71.0%, More preferably, the lower limit is 72.0%, and most preferably 78%.

The Bi ₂ O ₃ component, the B ₂ O ₃ component, and the SiO ₂ component are glass forming components, and are extremely effective in reducing the devitrification property of the glass and increasing the viscosity with respect to the liquidus temperature. However, if these contents are too large, it is difficult to obtain a desired partial dispersion ratio and Abbe number (ν _d ). Therefore, the total mass sum of the SiO ₂ component, the B ₂ O ₃ component, and the Bi ₂ O ₃ component is mass% with respect to the total mass of the oxide equivalent composition, preferably 90.0%, more preferably 91.0%, More preferably, the lower limit is 92.0%, and most preferably 96.0%. By using SiO ₂ together with B ₂ O ₃ , the liquidus temperature of the glass is lowered, the devitrification resistance is improved, the meltability, stability and chemical durability of the glass are increased, and in the visible region. Since transparency is also improved, it is preferable to use them simultaneously.

The GeO ₂ component is a component that increases the devitrification resistance of glass and the refractive index (n _d ) of glass and is effective in improving a high partial dispersion ratio. is there. However, if the content of the GeO ₂ component is too large, the meltability of the glass tends to be lowered. Accordingly, the content of the GeO ₂ component is mass% with respect to the total mass of the oxide conversion composition, preferably 10.0%, more preferably 9.0%, and most preferably 8.0%. The GeO ₂ component can be contained in the glass using, for example, GeO ₂ as a raw material.

The TeO ₂ component is an optional component that promotes clarification of the glass and has an effect of maintaining a high refractive index and reducing the dispersion of the glass. However, when there is too much the content, the devitrification resistance of glass will fall easily. Therefore, the content of the TeO ₂ component is mass% with respect to the total mass of the oxide conversion composition, preferably 5.0% or less, more preferably 2.0%, and most preferably 1.0%. On the other hand, the content of the TeO ₂ component is mass% with respect to the total mass of the oxide-converted composition, preferably 0% or more, more preferably 0.2%, and most preferably 0.4%. The TeO ₂ component can be contained in the glass using, for example, TeO ₂ as a raw material.

The CeO ₂ component is a component that adjusts the optical constant of the glass and promotes defoaming of the glass, and is an optional component in the optical glass of the present invention. In particular, by making the content of the CeO ₂ component 10.0% or less, solarization of the glass can be reduced. Therefore, the CeO ₂ component content with respect to the total glass mass of the oxide conversion composition is preferably 0.1%, more preferably 0.09%, and most preferably 0.08%. However, when a CeO ₂ component is contained, absorption tends to occur at a specific wavelength in the visible range. Therefore, it is preferable that the CeO ₂ component is not substantially contained in terms of coloring of the glass. The CeO ₂ component can be contained in the glass using, for example, CeO ₂ as a raw material.

<About ingredients that should not be included>
In the embodiment of the present invention, other components can be added as necessary within the range not impairing the characteristics of the optical glass according to the embodiment of the present invention. However, even when each transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag and Mo excluding Ti is contained alone or in combination with a small amount, the glass is colored and visible. Causes absorption at specific wavelengths in the region. Therefore, it is preferable that the optical glass using a wavelength in the visible region does not contain substantially. Here, “substantially free” means that it is not contained artificially unless it is mixed as an impurity.

  The Th component can be contained for the purpose of increasing the refractive index or improving the stability as glass, and the Cd and Tl components can be contained for the purpose of reducing the Tg. However, each component of Th, Cd, and Os has tended to be refrained from being used as a harmful chemical substance component in recent years. Therefore, not only in the glass manufacturing process but also in the processing process and disposal after commercialization, Measures are required. Therefore, it is preferable not to include substantially when the influence on the environment is emphasized.

  The lead component needs to take measures for environmental measures when manufacturing, processing, and disposing of the glass. Therefore, the cost is high, and the optical component according to the embodiment of the present invention should not contain the lead component. .

As ₂ O ₃ component is a component that is used to improve the blowout of foam (destructive property) when melting glass, but measures for environmental measures when manufacturing, processing, and disposing of glass. Therefore, it is not preferable to contain As ₂ O ₃ in the optical glass according to the example of the present invention.

[Production method]
The optical glass according to the embodiment 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 in a quartz crucible or a gold crucible and melted at a temperature range of 750 ° C. to 950 ° C. for 2 to 3 hours. Then, the mixture is stirred and homogenized, and after about 1 hour has passed since the temperature is lowered to about 800 ° C. to 650 ° C., it is cast into a mold and gradually cooled.

[Physical properties]
The optical glass according to the embodiment of the present invention has a desired refractive index (n _d ), a low partial dispersion ratio (θg, F), and an Abbe number (νd) within a desired range. 5%) and spectral transmittance (70%) have a wavelength on the short wavelength side, so that a remarkable effect can be exerted in correcting chromatic aberration of the optical element, and the degree of freedom in optical design can be expanded. In addition, since the glass transition point is low, the number of elements in the optical system can be reduced by using it as an aspheric lens, so that the entire optical system can be reduced in size. More specifically, the refractive index (n _d ) of the optical glass according to the embodiment of the present invention is preferably 2.3, more preferably 2.2, and most preferably 2.16. On the other hand, the refractive index (n _d ) of the optical glass according to the embodiment of the present invention is preferably 1.95, more preferably 1.98, and most preferably 2.02. Thereby, the freedom degree of optical design spreads and the thickness of the optical element can be further reduced. The partial dispersion ratio (θg · F) of the optical glass according to the embodiment of the present invention is preferably 0.67, more preferably 0.66, and most preferably 0.658. On the other hand, the partial dispersion ratio (θg · F) of the optical glass according to the embodiment of the present invention is preferably 0.63, more preferably 0.635, and most preferably 0.639. Thereby, a remarkable effect can be exerted in correcting chromatic aberration of the optical element, and the degree of freedom in optical design can be expanded. In addition, since the number of elements in the optical system can be reduced, the entire optical system can be reduced in size.

In addition, the upper limit of the Abbe number (ν _d ) of the optical glass according to the embodiment of the present invention is preferably 25, more preferably 22, and most preferably 20.5. On the other hand, the lower limit of the Abbe number (ν _d ) of the optical glass according to the embodiment of the present invention is not particularly limited, but is preferably 15, more preferably 16, and still more preferably 17. As a result, the degree of freedom in optical design is increased, and the device can be made thinner. In addition, since the number of elements in the optical system can be reduced, the entire optical system can be reduced in size.

  The spectral transmittance (70%) of the optical glass according to the embodiment of the present invention is preferably 500 nm, more preferably 470 nm, and most preferably 462 nm. On the other hand, the spectral transmittance (70%) of the optical glass according to the embodiment of the present invention is preferably 380 nm, more preferably 420 nm, and most preferably 436 nm. The upper limit of the spectral transmittance (5%) is preferably 450 nm, more preferably 420 nm, and most preferably 414 nm. On the other hand, the spectral transmittance (5%) of the optical glass according to the embodiment of the present invention is preferably 350 nm, more preferably 380 nm, and most preferably 399 nm. With these spectral transmittances, the absorption edge of the glass is positioned in the vicinity of the ultraviolet region, and the transparency of the glass in the visible region is enhanced, so this optical glass is preferably used as a material for optical elements such as lenses. Can do.

  In addition, the upper limit of the liquidus temperature of the optical glass according to the embodiment of the present invention is preferably 800 ° C., more preferably 750 ° C., and most preferably 723 ° C. Thereby, since the crystallization of the optical glass is reduced, it is possible to suppress the evaporation of the oxygen component more than necessary and the elution of the components contained in the equipment, and to further increase the transmittance of the optical glass. Moreover, since such optical glass is easily vitrified, the optical glass can be produced in a shorter time. On the other hand, the lower limit of the liquidus temperature of the optical glass according to the embodiment of the present invention is preferably 550 ° C, more preferably 600 ° C, and most preferably 625 ° C.

  Moreover, the liquid phase temperature of the above-mentioned optical glass and the viscosity at the liquid phase temperature are physical properties that are used as indicators of glass melt molding during mass production. Among these, when the viscosity at the liquidus temperature of the optical glass is too low, the glass preform tends to have striae, and when it is too high, it becomes difficult to cut the glass due to its own weight and surface tension. Therefore, for high-quality and stable production of optical glass, the logarithmic log η value of the viscosity (dPa · s) at the liquidus temperature is preferably 0.5, more preferably 0.6, and most preferably 0.8. 75 is the lower limit. On the other hand, the value of the logarithmic log η of the viscosity (dPa · s) at the liquidus temperature is preferably 2.5, more preferably 2.0, and most preferably 1.8.

[Preforms and optical elements]
A glass molded body can be produced from the produced optical glass using means such as reheat press molding or precision press molding. That is, a preform for mold press molding is prepared from optical glass, and after performing reheat press molding on the preform, polishing is performed to prepare a glass molded body, or for example, polishing is performed. The preform can be precision press-molded to produce a glass molded body. The glass molded body made of the optical glass according to the embodiment of the present invention can be used for applications of optical elements such as lenses, prisms, and mirrors, and can be typically used for digital cameras and projectors. In addition, the means for producing the glass molded body is not limited to these means.

The composition of Examples 1 to 32 of the present invention and the composition of Comparative Example 1, and the wavelength (λ ₇₀ ) and the spectral transmittance (5%) indicating the refractive index (n _d ) and the spectral transmittance (70%) are shown. Tables 1 to 4 show the results of wavelength (λ ₅ ), Abbe number (ν _d ), and partial dispersion ratio (θg · F). From the refractive index (n _d ), the wavelength (λ ₅ ) indicating the spectral transmittance (5%), the Abbe number (ν _d ), and the partial dispersion ratio (θg · F) shown in Tables 1 to 4, FIG. In the optical glass which concerns on the Example and comparative example of this invention, it is a figure which shows the relationship between a refractive index ( _nd ) and spectral transmittance (5%). FIG. 2 is a diagram showing the relationship between the refractive index (n _d ) and the spectral transmittance (70%) in the optical glasses according to the examples and comparative examples of the present invention. FIG. 3 is a diagram showing the relationship between the refractive index (n _d ) and the Abbe number (ν _d ) in the optical glasses according to the examples and comparative examples of the present invention. FIG. 4 is a diagram showing the relationship between the partial dispersion ratio (θg, f) and the spectral transmittance (5%) in the optical glasses according to the examples and comparative examples of the present invention. The following examples are merely for illustrative purposes, and are not limited to these examples.

  The optical glasses according to Examples 1 to 32 and Comparative Example 1 of the present invention shown in Tables 1 to 4 are all equivalent oxides, hydroxides, carbonates, nitrates, fluorides as raw materials of the respective components. High-purity raw materials used for ordinary optical glass such as hydroxides and metaphosphoric acid compounds were selected. The composition of each example shown in Tables 1 to 4 and the composition of each comparative example were weighed so as to have a glass weight of 400 g and mixed uniformly, and then charged into a quartz crucible or a gold crucible, After melting for about 2 hours to 3 hours in a temperature range of 750 ° C. to 950 ° C. in an electric furnace depending on the degree of difficulty of melting, stirring and homogenizing, and after about 1 hour has passed since the temperature was lowered to about 800 ° C. to 650 ° C. It was produced by casting into a mold and gradually cooling.

Here, the refractive index of the optical glass according to Examples 1 to 32 and Comparative Example 1 _{(n d)} and Abbe number ([nu _d) was measured according to Japan Optical Glass Industry Society Standard JOGIS01-2003. In addition, the optical glass used for this measurement used what was processed in the slow cooling furnace by making slow cooling temperature-fall rate into -25 degrees C / hr.

About the light transmittance of the wavelength of the visible region of Examples 1-32 and the optical glass which concerns on the comparative example 1, it measured according to Japan Optical Glass Industry Association standard JOGIS02. Specifically, a face parallel polished product having a thickness of 10 ± 0.1 mm is measured for a spectral transmittance of 200 nm to 800 nm in accordance with JISZ8722, and a spectral transmittance including reflection loss (λ ₅ ) (spectral transmittance of 5%). Hour wavelength) and spectral transmittance (λ ₇₀ ) (wavelength when the spectral transmittance is 70%).

  The liquid phase temperature of the optical glasses according to Examples 1 to 32 and Comparative Example 1 is formed from a glass having the same composition as the raw glass, and a glass sample pulverized into granules having a diameter of about 2 mm is placed on a platinum plate, and 500 ° C Crystals are observed in the glass, measured by observing with a microscope with a magnification of 80 times the presence or absence of crystals in the glass after being held for 30 minutes in a furnace with a temperature gradient of ˜900 ° C. and then cooled. It is determined from the lowest temperature at which devitrification does not occur. The viscosity value at the liquidus temperature is obtained from the viscosity η (Pa · s) by a ball pulling viscometer (model number BVM-13LH manufactured by Opto Enterprise Co., Ltd.).

As shown in Tables 1 to 4, the optical glasses according to Examples 1 to 32 of the present invention have a refractive index (n _d ) of 2.021 or more and 2.111 or less, and an Abbe number (ν _d ) of 17. 0.8 to 20.3, the partial dispersion ratio (θg · F) is 0.639 to 0.658, and the spectral transmittance (λ ₅ ) (wavelength when the spectral transmittance is 5%) is 399 nm or more. The spectral transmittance (λ ₇₀ ) (wavelength when the spectral transmittance was 70%) was 436 nm or more and 462 nm or less. On the other hand, the optical glass of Comparative Example 1 has a refractive index (n _d ) of 2.092, an Abbe number (ν _d ) of 16.5, and a partial dispersion ratio (θg · F) of 0.676. The spectral transmittance (λ ₅ ) (wavelength when the spectral transmittance was 5%) was 432, and the spectral transmittance (λ ₇₀ ) (wavelength when the spectral transmittance was 70%) was 477.

In FIG. 1, the vertical axis indicates the refractive index (n _d ), the horizontal axis indicates the spectral transmittance (5%), “◇” is an example, and “□” is a comparative example. In FIG. 2, the vertical axis indicates the refractive index (n _d ), the horizontal axis indicates the spectral transmittance (70%), “、” is an example, and “□” is a comparative example. In FIG. 3, the vertical axis indicates the refractive index (n _d ), the horizontal axis indicates the Abbe number (ν _d ), “、” is an example, and “□” is a comparative example. In FIG. 4, the vertical axis indicates the partial dispersion ratio (θg, f), the horizontal axis indicates the spectral transmittance (5%), “◇” is an example, and “□” is a comparative example. Therefore, the optical glass according to the embodiment of the present invention has a desired refractive index (n _d ), a low partial dispersion ratio (θg, F), and an Abbe number (ν _d ) within a desired range, but has a spectroscopic property. It became clear that the transmittance (5%) and the spectral transmittance (70%) have a wavelength on the short wavelength side.

The optical glass according to the embodiment of the present invention has a desired content by setting the content of the Bi ₂ O ₃ component, the content of the B ₂ O ₃ component, and the content of the SiO ₂ component within a predetermined range. Spectral transmittance (5%) and spectral transmittance (70%) have a refractive index (n _d ), a low partial dispersion ratio (θg, F), and an Abbe number (ν _d ) within a desired range. It became clear that it has a wavelength on the short wavelength side.

Claims (12)

The Bi ₂ O ₃ component is 70.0% or more and 90.0% or less, the B ₂ O ₃ component is 6.0% or more and 20.0% or less, and the SiO ₂ component in mass% with respect to the total glass mass of the oxide conversion composition. An optical glass characterized by containing more than 0% and 20% or less of each component. _2. The optical component according to claim 1, comprising a total of 90.0% or more of a Bi ₂ O ₃ component, a B ₂ O ₃ component, and a SiO ₂ component in mass% with respect to the total glass mass of the oxide equivalent composition. Glass. According to claim 1 or 2, characterized in that it contains by mass% with respect to the glass the total weight of the oxide composition in terms of _Bi 2 _{O 3} component and _Nb 2 _{O 5} component and more than 70.0 and a ZrO ₂ component in total Optical glass.   Any one or more of MgO component, CaO component, SrO component, BaO component and ZnO component is contained in an amount of 0% by mass with respect to the total mass of the glass in terms of oxide composition. 4. The optical glass according to any one of 3. By mass% with respect to the total mass of the glass in oxide equivalent composition,
Li ₂ O component 0-8.0%
Na ₂ O component from 0 to 8.0%
K ₂ O component 0 to 8.0%
Al ₂ O ₃ component 0 to 10.0%
ZrO ₂ component 0 to 10.0%
Ta ₂ O ₅ component 0 to 10.0%
WO ₃ components 0 to 10.0%
La ₂ O ₃ component 0 to 10.0%
Gd ₂ O ₃ component 0 to 10.0%
Y ₂ O ₃ component 0 to 10.0%
Yb ₂ O ₃ component 0 to 10.0%
P ₂ O ₅ component 0 to 10.0%
Sb ₂ O ₃ component 0-5.0%
The optical glass according to claim 1, further comprising: The optical glass according to any one of claims 1 to 5, wherein the TeO ₂ component is contained in an amount of 0% or more and 5% or less by mass% with respect to the total mass of the glass in terms of oxide. A wavelength (λ ₅ ) indicating spectral transmittance (5%) in a sample having a thickness of 10 mm is 350 nm to 450 nm and a wavelength (λ ₇₀ ) indicating spectral transmittance (70%) in a sample having a thickness of 10 mm is 380 nm to 500 nm. The optical glass according to claim 1, wherein the optical glass is as follows.   8. The optical glass according to claim 1, wherein the partial dispersion ratio (θg, F) is 0.63 or more and 0.67 or less. Refractive index (n _d) is not less 1.95 or more, an Abbe's number ([nu _d) optical glass according to any one of claims 1 to 8, characterized in that 15 to 25.   A preform for precision press molding comprising the optical glass according to any one of claims 1 to 9.   An optical element comprising the optical glass according to claim 1. An optical element formed by precision pressing the preform according to claim 10.

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