JP6055876B2 - Optical glass, preform and optical element - Google Patents

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. Conventionally, as such high refractive index (n _d ) and high dispersion glass, for example, the refractive index (n _d ) is 1.91 or more and the Abbe number (ν _d ) is 17.2 or more and 33.1 or less. The optical glass having was used.

  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.

  On the other hand, Patent Document 1 describes an optical glass having a desired refractive index and spectral transmittance.

JP 2010-260739 A

However, the lower the Abbe number (ν _d ) of the glass disclosed in Patent Document 1, the lower the transparency to visible light (the longer the value of λ ₇₀ ), and the lower the Abbe number (ν _d ), the yellow and orange Is colored. Therefore, even if the glass disclosed in Patent Document 1 has a desired refractive index and high dispersion, it is not suitable for applications that transmit light in the visible region. Further, the optical glass disclosed in Patent Document 1 has 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 component, alkaline earth metals (Mg, Ca, any one or more of Sr and Ba), the content of ZnO component and TeO ₂ component By setting the value within a predetermined range, it has a high refractive index (n _d ) and a long spectral transmittance (5%), but is highly transparent to visible light, and is devitrified during the production and processing of glass. An object of the present invention is to provide an optical glass that does not easily cause fogging and is easy to produce a preform material or an optical element by polishing, and a preform using the optical glass.

As a result of intensive studies and studies to solve the above-mentioned problems, the present inventor has at least the content of Bi ₂ O ₃ component and alkaline earth metal (any one or more of Mg, Ca, Sr and Ba). By setting the content, the content of the ZnO component and the content of the TeO ₂ component within the predetermined ranges, the refractive index (n _d ) of the optical glass is increased, and the wavelength exhibiting the spectral transmittance (5%), that is, The inventors have found that the spectral transmittance (λ ₅ ) is increased, and have completed the present invention.

In the optical glass according to the embodiment of the present invention, the Bi ₂ O ₃ component is 75.0% or more by mass% based on the oxide, and the MgO component, CaO component, SrO component and BaO component are contained by mass% of the oxide group. Any one or more is less than 10.0%, ZnO component is less than 10.0% by mass based on oxide, and TeO ₂ component is greater than 0% and less than 1.5% by mass percent based on oxide. Each is contained , the refractive index (nd) is 2.15 or more, and the Abbe number (νd) is 13.0 or more and 16.0 or less .

The optical glass may contain 98.0% or less of a Bi ₂ O ₃ component.

The optical glass may contain 90.0% or more of the Bi ₂ O ₃ component and the B ₂ O ₃ component in total.

  In the optical glass, one or more of MgO component, CaO component, SrO component, and BaO component may be contained in excess of 0%.

  In the optical glass, the ZnO component may contain more than 0%.

  In the optical glass, the MgO component exceeds 0% and less than 10.0%, and / or the CaO component exceeds 0% and less than 10.0%, and / or the SrO component exceeds 0% and 10%. It may further contain less than 0.0% and / or each component with a BaO component of more than 0% and less than 10.0%.

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

  An optical element according to an embodiment of the present invention comprises any one of the optical glasses described above.

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

According to the present invention, the content of Bi ₂ O ₃ component, the content of alkaline earth metal (any one or more of Mg, Ca, Sr and Ba), the content of ZnO component and the content of TeO ₂ component By setting the value within a predetermined range, it has a high refractive index (n _d ) and a long spectral transmittance (5%), but is highly transparent to visible light, and is devitrified during the production and processing of glass. It is possible to provide an optical glass that does not easily cause fogging and is easy to produce a preform material or an optical element by polishing, and a preform using the optical glass.

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 refractive index ( _nd ) and Abbe number ((nu) _d ).

In the optical glass according to the embodiment of the present invention, the Bi ₂ O ₃ component is 75.0% or more by mass% based on the oxide, and the alkaline earth metal (Mg, Ca, Sr and Ba is mass% based on the oxide). By containing any one or more) less than 10.0%, less than 10.0% ZnO component by mass% based on oxide, and less than 10.0% TeO ₂ component by mass% based on oxide. The refractive index (n _d ) can be 2.15 or more and the spectral transmittance (5%) can be 450 nm or less. By setting the above-described components within a predetermined range, the refractive index (n _d ) and spectral transmittance (5%) of the optical glass are increased. For this reason, while having a high glass refractive index (n _d ) and a long spectral transmittance (5%), it is highly transparent to visible light, and devitrification and fogging are unlikely to occur during glass production and processing. It is possible to obtain an optical glass that facilitates the production of 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% based on the oxide. 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 abrasion degree, and the viscosity with respect to the liquidus temperature. Is an optional 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 tend to be lowered, and the meltability of the glass tends to deteriorate. Accordingly, the upper limit of the content of the SiO ₂ component is 0.0% by mass, preferably 10.0%, more preferably 7.0%, and most preferably 3.0%. The SiO ₂ component can be contained in the glass using, for example, SiO ₂ as a raw material.

The B ₂ O ₃ component is a component that has an effect of improving scientific 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. Accordingly, the content of the B ₂ O ₃ component is expressed by mass% based on the oxide, preferably 15.0%, more preferably 12.0%, and most preferably 9.0%. On the other hand, the content of the B ₂ O ₃ component is mass% based on the oxide, preferably 1.0%, more preferably 2.0%, and most preferably 4.0%. 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 SiO ₂ component and the B ₂ O ₃ component do not necessarily need to be contained, but these are glass forming components and are very effective in reducing the devitrification of the glass and increasing the viscosity with respect to the liquidus temperature. Therefore, it is preferable that at least one of both components contains more than 0%. However, if these contents are too large, it is difficult to obtain a desired partial dispersion ratio and Abbe number (ν _d ). Therefore, the mass sum of the SiO ₂ component and the B ₂ O ₃ component is mass% based on the oxide, preferably more than 0%, more preferably 2.5%, and most preferably 5.0%. . On the other hand, the upper limit of the mass sum of the SiO ₂ component and the B ₂ O ₃ component is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. 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 Al ₂ O ₃ component is an optional component useful for improving the chemical durability and mechanical strength of 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. Therefore, the upper limit of the content of the Al ₂ O ₃ component is 10.0% by mass, preferably 10.0%, more preferably 5.0%, and most preferably 1.0%. The Al ₂ O ₃ component can be contained in the glass using, for example, Al ₂ O ₃ or Al (OH) ₃ as a raw material.

The Y ₂ O ₃ component is an optional component useful for reducing the glass and increasing the refractive index. However, if the content is too large, the glass stability tends to be lowered. Accordingly, the content of the Y ₂ O ₃ component is preferably less than 10.0%, more preferably 5.0%, and most preferably 1.0%.

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 less than 10.0%, more preferably 5.0%, and most preferably 1.0%.

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. Therefore, the content of the Gd ₂ O ₃ component is preferably less than 10.0%, more preferably 5.0%, and most preferably 1.0%.

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. Accordingly, the content of the Yb ₂ O ₃ component is preferably less than 10.0%, more preferably 5.0%, and most preferably 1.0%.

The 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 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. The mass sum of the Ln ₂ O ₃ component (wherein Ln is at least one selected from the group consisting of Y, La, Gd, and Yb) is mass% based on the oxide, preferably 10 Less than 0.0%, more preferably 5.0%, and still more preferably 2.0%. In particular, it is most preferable that the mass sum of the Ln ₂ O ₃ component is less than 1.0% because the coloring of the glass can be further reduced. The Y ₂ O ₃ component, La ₂ O ₃ component, Gd ₂ O ₃ component and Yb ₂ O ₃ component of the glass are, for example, La ₂ O ₃ , La (NO ₃ ) 3 .XH ₂ O (X is an arbitrary Integer), Gd ₂ O ₃ , Y ₂ O ₃ , Yb ₂ O _{3 and the} like.

The TiO ₂ component is an optional component effective for increasing the refractive index (n _d ) and partial dispersion ratio of the glass and lowering the liquidus temperature. 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% based on the oxide, preferably 10.0%, more preferably 5.0%, and most preferably 1.0%. The TiO ₂ component can be contained in the glass using, for example, TiO ₂ as a raw material.

The ZrO ₂ component is an optional component useful for improving the chemical durability and mechanical strength of the 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 upper limit of the content of the ZrO ₂ component is 10.0% by mass, preferably 10.0%, more preferably 5.0%, and most preferably 1.0%. 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. Therefore, the content of the Nb ₂ O ₅ component is, in terms of mass% based on the oxide, preferably exceeding 0%, more preferably 0.05%, and most preferably 0.1%. On the other hand, 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% based on the oxide, preferably 10.0%, more preferably 5.0%, and most preferably 1.0%. The Nb ₂ O ₅ component can be contained in the glass using, for example, Nb ₂ O ₅ as a raw material.

The TiO ₂ component does not necessarily need to be contained, but it is preferable that the Nb ₂ O ₅ component is always included, and a predetermined amount of Bi ₂ O ₃ component (described later), a TiO ₂ component or an Nb ₂ O ₅ component By using together, it is possible to further increase the partial dispersion ratio of the glass while maintaining high transmittance. Therefore, the total content of the TiO ₂ component and the Nb ₂ O ₅ component is in mass% based on the oxide, and preferably exceeds 0%, more preferably 0.2%, and most preferably 0.5%. To do. On the other hand, when the total content of the TiO ₂ component and the Nb ₂ O ₅ component is too large, the stability of the glass is lowered, and the transmittance for light having a wavelength in the visible region is likely to be lowered. Therefore, the total content of the TiO ₂ component and the Nb ₂ O ₅ component is preferably mass% based on the oxide, preferably 10.0%, more preferably 5.0%, and most preferably 3.0%. To do.

By including the Nb ₂ O ₅ component and the B ₂ O ₃ component as Nb ₂ O ₅ components / B ₂ O ₃ components, it is possible to contribute to stabilization of the glass. Therefore, the content ratio of Nb ₂ O ₅ component / B ₂ O ₃ component is preferably 0.001, more preferably 0.01, and most preferably 0.03. On the other hand, when the Nb ₂ O ₅ component / B ₂ O ₃ content of the component is too large, the transmittance for light having a wavelength in the visible region tends to decrease the stability of the glass is lowered. Therefore, the ratio of the content of Nb ₂ O ₅ component / B ₂ O ₃ component is preferably 0.5, more preferably 0.25, and most preferably 0.20.

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 the Ta ₂ O ₅ component is too large, the stability of the glass is lowered, the transmittance is likely to be lowered, and the raw material cost of the glass is significantly increased. Therefore, the content of the Ta ₂ O ₅ component is mass% based on oxide, preferably 10.0%, more preferably 5.0%, and most preferably 3.0%. The Ta ₂ O ₅ component can be contained in the glass using, for example, Ta ₂ O ₅ as a raw material.

By using the Nb ₂ O ₅ component and the Ta ₂ O ₅ component together, it is possible to contribute to the stabilization of the glass while maintaining a high transmittance. Accordingly, the total content of the Nb ₂ O ₅ component and the Ta ₂ O ₅ component is preferably 10.0%, more preferably 5.0%, and most preferably 1.0% by mass% based on the oxide. The upper limit.

The WO ₃ component is an optional component useful for increasing the refractive index (n _d ) of glass, improving the partial dispersion ratio of 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 upper limit of the content of the WO ₃ component is 10.0% by mass, preferably 10.0%, more preferably 5.0%, and most preferably 3.0%. The WO ₃ component can be contained in the glass using, for example, WO ₃ as a raw material.

The ZnO component is a 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 content of the ZnO component is preferably less than 10.0%, more preferably 5.0%, and most preferably 3.0%. In addition, an optical glass having desired optical characteristics can be produced in the embodiment of the present invention without containing a ZnO component, but in order to facilitate the adjustment of the partial dispersion ratio and the Abbe number (ν _d ). Preferably contains more than 0%, more preferably 0.1%, and most preferably 0.2% as a lower limit.

The MgO component is an optional component useful for increasing the dispersion of glass and improving devitrification resistance. However, when the content of the MgO component is too large, the stability of the glass tends to be lowered, so that the visible light transmittance is liable to be lowered, and the glass is easily devitrified by reheating treatment during press molding. Therefore, the content of the MgO component is, in mass% based on the oxide, preferably less than 10.0%, more preferably 5.0%, and most preferably 3.0%. On the other hand, the content of the MgO component is in mass% based on the oxide, and preferably exceeds 0%, more preferably 0.1%, and most preferably 0.2%. 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. Accordingly, the content of the CaO component and the mass% based on the oxide are preferably less than 10.0%, more preferably 5.0%, and most preferably 3.0%. On the other hand, the content of the CaO component is mass% based on the oxide, 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 ). Accordingly, the content of the SrO component is, in terms of mass% based on the oxide, preferably less than 10.0%, more preferably 5.0%, and most preferably 3.0%. On the other hand, the content of the SrO component is in mass% based on the oxide, 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 ). Accordingly, the upper limit of the content of the BaO component is preferably less than 10.0%, more preferably 5.0%, and most preferably 3.0% in terms of mass% based on oxide. On the other hand, the content of the BaO component is in mass% based on the oxide, 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, in terms of mass% based on oxide, 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 in mass% based on the oxide, and preferably exceeds 0%, more preferably 0.1%, and most preferably 0.2%.

In the RO component, the SiO ₂ component, and the B ₂ O ₃ component, by containing as RO component / (SiO ₂ component + B ₂ O ₃ component), the devitrification of the glass is reduced and the viscosity with respect to the liquidus temperature is increased. be able to. Therefore, the ratio of the content of RO component / (SiO ₂ component + B ₂ O ₃ component) is preferably 0.5, more preferably 0.4, and most preferably 0.3. On the other hand, the ratio of the content of RO component / (SiO ₂ component + B ₂ O ₃ component) is preferably more than 0, more preferably 0.05, and most preferably 0.1.

The Li ₂ O component is a component that improves the stability of the glass to reduce devitrification and coloring, and is an optional component that is effective in lowering the Tg of the glass. However, if 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 tends to be lowered. Become. Therefore, the content of the Li ₂ O component is mass% based on the oxide, preferably 10.0%, more preferably 5.0%, and most preferably 3.0%. 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, if the content of the Na ₂ O component is too large, the refractive index (n _d ) of the glass decreases, the stability of the glass tends to decrease, and the chemical durability and mechanical strength of the glass also tend to decrease. . Therefore, the content of the Na ₂ O component is mass% based on the oxide, preferably 10.0%, more preferably 5.0%, and most preferably 3.0%. The Na ₂ O component can be contained in the glass using, for example, Na ₂ CO ₃ , NaNO ₃ or the like 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 upper limit of the content of the K ₂ O component is 10.0% by mass on the oxide basis, preferably 10.0%, more preferably 5.0%, and most preferably 3.0%. The K ₂ O component can be contained in the glass using, for example, K ₂ CO ₃ or KNO ₃ 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 significant 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. Accordingly, 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 5.0%, and most preferably 3.0%.

The Sb ₂ O ₃ component is an optional component that has an effect of promoting glass clarification. 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, by mass% based on oxide, preferably 3.0%, more preferably 2.0%, and most preferably 1.0%. 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. The component for clarifying and defoaming the glass is not limited to the above Sb ₂ O ₃ component, and a known fining agent, defoaming agent, or a combination thereof in the field of glass production can be used. .

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 upper limit of the content of the P ₂ O ₅ component is mass% based on the oxide, preferably 10.0%, more preferably 5.0%, and most preferably 3.0%. The P ₂ O ₅ component is used in the glass by using, for example, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , Na (PO ₃ ), BPO ₄ , H ₃ PO _4, etc. as raw materials. It can contain.

The Bi ₂ O ₃ component is a component that increases the refractive index (n _d ) of the glass, increases the partial dispersion ratio of the glass, and is effective for reducing the 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 75.0% 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 preferably 55.0% by mass on the oxide basis, preferably 75.0%, more preferably 77.0%, and most preferably 79.0%. On the other hand, the content of the Bi ₂ O ₃ component in terms of mass% based on oxide is preferably 98.0%, more preferably 96.0%, and most preferably 94.0%. Since the stability of the glass is improved, the coloring of the 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 and the Nb ₂ O ₅ component together, the Bi ₂ O ₃ component and the Nb ₂ O ₅ component can contribute to 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 and the Nb ₂ O ₅ component is preferably 90.0%, more preferably 94.0%, and most preferably 98.0% by mass% based on the oxide. The lower limit.

The Bi ₂ O ₃ component and the B ₂ O ₃ component are preferably used in combination, but the B ₂ O ₃ component is not necessarily included. Bi ₂ O ₃ component and B ₂ O ₃ component contribute to higher refractive index and glass stabilization, and can further increase the partial dispersion ratio. Therefore, the total content of the Bi ₂ O ₃ component and the B ₂ O ₃ component is preferably 90.0%, more preferably 94.0%, and most preferably 98.0% by mass% based on the oxide. The lower limit.

The GeO ₂ component is a component that increases the devitrification resistance of the glass and increases the refractive index (n _d ) of the glass and is effective in improving a high partial dispersion ratio. However, it is a component that can be arbitrarily added because it is expensive. is there. However, if the content of the GeO ₂ component is too large, the meltability of the glass tends to be lowered. Therefore, the content of the GeO ₂ component is, in terms of mass% based on oxide, 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 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. Accordingly, the content of the TeO ₂ component is, in terms of mass% based on oxide, preferably less than 10.0%, more preferably 5.0%, and most preferably 1.5%. On the other hand, the content of the TeO ₂ component is mass% based on the oxide, and preferably exceeds 0%, more preferably 0.1%, and most preferably 0.2%. The TeO ₂ component can be contained in the glass using, for example, TeO 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 tends to be refrained from being used as a harmful chemical substance component in recent years. 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 include 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]
Since the optical glass according to the embodiment of the present invention has a high refractive index (n _d ) and a long spectral transmittance (5%), it can exhibit a remarkable effect in correcting chromatic aberration of an optical element, and can be optically designed. The degree of freedom 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. More specifically, the refractive index ( _nd ) of the optical glass according to the embodiment of the present invention is preferably 2.4, more preferably 2.35, and most preferably 2.3. On the other hand, the refractive index (n _d ) of the optical glass according to the embodiment of the present invention is preferably 2.15, more preferably 2.17, and most preferably 2.2. As a result, the degree of freedom in optical design is widened, and a large amount of light refraction can be obtained even if the optical element is made thinner. The spectral transmittance (70%) of the optical glass according to the embodiment of the present invention is preferably 520 nm, more preferably 515 nm, and most preferably 510 nm. On the other hand, the spectral transmittance (70%) of the optical glass according to the embodiment of the present invention is preferably 460 nm, more preferably 470 nm, and most preferably 480 nm. Thereby, transparency with respect to visible light is high, and devitrification and fogging can hardly occur during glass production and processing. The spectral transmittance (5%) of the optical glass according to the embodiment of the present invention is preferably 450 nm, more preferably 449 nm, and most preferably 448 nm. On the other hand, the spectral transmittance (5%) of the optical glass according to the embodiment of the present invention is preferably 415 nm, more preferably 420 nm, and most preferably 425 nm. Thereby, transparency with respect to visible light is high, and devitrification and fogging can hardly occur during glass production and processing.

Moreover, it is preferable that the optical glass which concerns on embodiment of this invention has high dispersion (low Abbe number). More specifically, 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 20, and most preferably 16. 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 13, more preferably 13.5, and still more preferably 14. 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. In addition, since the number of elements in the optical system can be reduced, the entire optical system can be reduced in size.

[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.

Compositions of Examples 1 to 68 and Comparative Examples 1 and 2 of the present invention, a refractive index (n _d ), a wavelength indicating spectral transmittance (70%) (λ ₇₀ ), and a spectral transmittance (5%) Tables 1 to 7 show the results of the wavelength (λ ₅ ) and the Abbe number (ν _d ) indicating From the wavelength (λ ₅ ) and Abbe number (ν _d ) indicating the refractive index (n _d ), spectral transmittance (5%) shown in Tables 1 to 7, FIG. 1 shows an example of the present invention and a comparative example. It is a figure which shows the relationship between the refractive index ( _nd ) of the optical glass which concerns on, and spectral transmittance (5%). FIG. 2 is a diagram showing the relationship between the refractive index (n _d ) and the Abbe number (ν _d ) of optical glasses according to 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 68 and Comparative Examples 1 and 2 of the present invention shown in Tables 1 to 7 are oxides, hydroxides, carbonates, nitrates corresponding to the raw materials of the respective components, respectively. High-purity raw materials used for ordinary optical glasses such as fluorides, hydroxides, and metaphosphoric acid compounds were selected. The composition of each example shown in Tables 1 to 7 and the composition of each comparative example were weighed so that the glass weight would be 400 g and mixed uniformly, and then put into a quartz crucible or a gold crucible, and the glass composition 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. Comparative Example 2 was not vitrified.

Here, the refractive index of the optical glass according to Examples 1 to 68 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 the optical glass which concerns on Examples 1-68 and 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%).

In general, optical glass tends to decrease the light transmittance of visible wavelengths when the partial dispersion ratio is increased, and it is difficult to produce an optical glass in which these are compatible. However, as shown in Tables 1 to 7, the optical glasses according to Examples 1 to 68 of the present invention have a refractive index (n _d ) of 2.2 or more and 2.4 or less, and a spectral transmittance (λ ₅ ) (Wavelength at 5% spectral transmittance) was 425 nm or more and 450 nm or less. On the other hand, the optical glass of Comparative Example 1 had a refractive index (n _d ) of 1.85, and the wavelength at the time of spectral transmittance (λ ₅ ) was 430 nm. For this reason, unlike the optical glass of Comparative Example 1, the optical glass according to Examples 1 to 68 of the present invention has a high refractive index (n _d ) and a wavelength at a light transmittance (λ ₅ ) at a visible wavelength. It became clear that it was compatible with the height of.

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 Abbe number (ν _d ), “◇” is an example, and “□” is a comparative example. As shown in FIGS. 1 and 2, in the optical glasses according to Examples 1 to 67 of the present invention, the refractive index (n _d ) of the glass is 2.2 or more and 2.4 or less, and the spectral transmittance (5 %) Was 425 nm or more and 450 nm or less. On the other hand, the optical glass according to Comparative Example 1 had a glass refractive index (n _d ) of 1.85 and a spectral transmittance (5%) of 430 nm. Therefore, it became clear that the optical glass according to the example of the present invention has a desired refractive index (n _d ) and a spectral transmittance (5%).

The optical glass according to the embodiment of the present invention includes at least the content of Bi ₂ O ₃ component and the content of alkaline earth metal (any one or more of Mg, Ca, Sr and Ba), the content of ZnO component and It was revealed that by setting the content of the TeO ₂ component within a predetermined range, it has a high refractive index (n _d ) and a long spectral transmittance (5%).

Claims (3)

98.0% 75.0% more than the _Bi 2 _{O 3} component in weight percent on the oxide basis below, MgO component in weight percent on the oxide basis, CaO component, any one or more of SrO component and BaO components 1. More than 0% and less than 10.0%, ZnO component in excess of 0% by mass% and less than 10.0%, and TeO ₂ component in excess of 0% by mass% based on oxide. 5% or less, Nb ₂ O ₅ component in excess of 0% by mass% based on oxide, 5.0% or less, B ₂ O ₃ component in mass% based on oxide, 1% or more and 15.0% or less Each of them contains 90.0% or more of the Bi ₂ O ₃ component and the B ₂ O ₃ component in total, and the content ratio of Nb ₂ O ₅ component / B ₂ O ₃ component is 0.01 to 0.10,
A wavelength (λ ₅ ) indicating spectral transmittance (5%) in a sample having a thickness of 10 mm is 450 nm or less, and a wavelength (λ ₇₀ ) indicating spectral transmittance (70%) is 520 nm or less,
Refractive index (nd) is 2.15 or more,
An optical glass having an Abbe number (νd) of 13.0 or more and 16.0 or less.   A preform for precision press molding comprising the optical glass according to claim 1.   An optical element comprising the optical glass according to claim 1.

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