TW201900575A - Optical glass, preform, and optical element having properties of high acid resistance and higher partial dispersion - Google Patents

Abstract

The invention provides an optical glass, a preform and an optical element. The problem of the present invention is to obtain a glass whose partial dispersion ratio (θ g, F) and Abbe number (ν _d ) satisfy (-0.00162 × ν _d +0.625) ≦ (θ g, F) ≦ ( -0.00162 × ν _d +0.660), and high acid resistance. The glass is based on mass%, containing 20.0% to 60.0% of P ₂ O ₅ component, 5.0% to 45.0% of BaO component, and more than 0% to 15.0% of Ln ₂ O ₃ component. Partial dispersion ratio (θ g, F) and A The number of shells (ν _d ) corresponds to the relationship of (-0.00162 × ν _d +0.625) ≦ (θ g, F) ≦ (-0.00162 × ν _d +0.660); chemical durability (acid resistance) measured by powder method ) Are grades 1 to 5.

Description

   Optical glass, preform and optical element   

The present invention relates to optical glass, a preform, and an optical element.

In recent years, the digitization and high definition of devices using optical systems have been rapidly developed. In the field of various optical devices such as digital cameras or video cameras, video projectors, and image reproduction (projection) devices such as projection televisions, The need to increase processing yields is increasing.

In addition, as the optical characteristic index focused on optical design, a partial dispersion ratio (θ g, F) is used. In order to properly correct the secondary spectrum, it is necessary to use an optical with a relatively large partial dispersion on a lens with a low dispersion side. material.

Generally speaking, chromatic aberration is corrected by combining a convex lens with low dispersion and a concave lens with high dispersion, but this combination can only correct aberrations in the red and green areas, while aberrations in the blue area still exist. . This blue area aberration that cannot be completely removed is called the secondary spectrum. In the case of correcting the secondary spectrum, it is necessary to perform an optical design that takes into account the movement of the g-line (435.835nm) in the blue region. At this time, a partial dispersion ratio (θ g, F) is used as an optical characteristic index focused on in optical design. In the above-mentioned optical system combining a lens with low dispersion and a lens with high dispersion, an optical material with a large partial dispersion ratio (θ g, F) is used for the lens on the low dispersion side, and it is used for the lens on the high dispersion side Optical materials with small partial dispersion ratio (θ g, F), so that the secondary spectrum can be well corrected.

The partial dispersion ratio (θ g, F) can be expressed by the following formula (1).

[Formula (1)] θ g, F = (n _g -n _F ) / (n _F -n _C )

In optical glass, there is a nearly straight-line relationship between the partial dispersion ratio (θ g, F) and the Abbe number (ν _d ), which indicates partial dispersion in the short wavelength region. The straight line representing this relationship is called a normal line, and it is expressed by the following straight line: When the partial dispersion ratio (θ g, F) is used as the vertical axis, and the Abbe number (ν _d ) is used as the horizontal coordinate of the horizontal axis, Partial dispersion ratio and Abbe number of NSL7 and PBM2 draw 2 points, and then connect the two points to form a straight line (refer to Figure 1). Although the standard glass used as a standard line standard varies with each optical glass manufacturer, each company defines it with almost the same inclination and intercept (NSL7 and PBM2 are manufactured by Ohara Corporation) Optical glass, the Abbe number (ν _d ) of PBM2 is 36.3, the partial dispersion ratio (θ g, F) is 0.5828, the Abbe number of NSL7 (ν _d ) is 60.5, and the partial dispersion ratio (θ g, F) is 0.5436 ).

In addition, when the glass is processed in a glass manufacturing step, if the workability of the glass is poor, the surface of the glass is liable to cause discoloration damage or cloudiness during the grinding / polishing step or the washing step. At this time, in order not to cause discoloration damage or turbidity inside the glass, a step of grinding / polishing the glass surface is added, so that a lot of time is spent on the processing step.

Especially in the field of low-dispersion side (for example, Abbe number is 50 or more and 70 or less), optical glass containing a P ₂ O ₅ component as a main component and a BaO component is generally liable to deteriorate in acid resistance or abrasion. And the glass has poor processability, so an optical glass with good acid resistance is desired.

Furthermore, it is desirable that an optical element incorporated in an optical device that generates heat, such as a projector, can constitute an optical system that is unlikely to affect the imaging characteristics of the optical system due to temperature fluctuations in the use environment.

In the production of optical glass for optical elements, there is an increasing demand for glass materials with improved processability or large partial dispersion ratios: a refractive index (n _d ) of 1.57 to 1.65, and an Abbe number (ν _d ) of 50 or more. Phosphoric acid glass with high Abbe number below 70 and no fluorine.

    [Prior technical literature]         [Patent Literature]    

Patent Document 1: Japanese Patent Application Laid-Open No. 2010-202418.

In order to apply optical glass to various optical devices, steps such as grinding or cleaning are performed. An abrasive is used in the polishing step, and a lotion or the like is used in the cleaning step. If the chemical durability of the glass is poor, especially if the acid resistance is poor, the glass is likely to be damaged.

In addition, in optical design, it is more desirable to use partial dispersion on the low dispersion side. Furthermore, when constructing an optical system that does not easily affect imaging performance due to temperature fluctuations, it is better to use two types of optical elements: a glass whose refractive index becomes lower as the temperature rises and whose temperature coefficient of the relative refractive index is a negative value. An optical element composed of glass whose refractive index becomes higher as the temperature becomes higher and the temperature coefficient of the relative refractive index is a positive value, thereby correcting the influence of temperature changes on imaging characteristics and the like. It is known that the temperature coefficient of the relative refractive index is related to the linear expansion coefficient, and as the phosphoric acid-based glass on the low dispersion side, a glass with a small linear expansion coefficient is preferred.

However, the glass described in Patent Document 1 cannot be said to sufficiently satisfy such a requirement.

The present invention has been made in view of the above-mentioned problems, and aims to make glass processing in the polishing step and the cleaning step easy, and in terms of optical design, it has a low refractive index and low dispersion, and it also has a part The characteristic of relatively large dispersion.

In order to solve the above-mentioned problems, the present inventors focused on the results of cumulative test research and found that the acid resistance measured by the powder method can be obtained by using the P ₂ O ₅ component as the main component and the BaO component and the rare earth element component as essential components. The glass with good properties and relatively large dispersion has completed the present invention.

Specifically, the present invention provides the following.

(1) An optical glass, based on mass%, containing 20.0% to 60.0% of P ₂ O ₅ component, 5.0% to 45.0% of BaO component, and more than 0% to 15.0% of Ln ₂ O ₃ component; partial dispersion ratio (θ g, F) and the Abbe number (ν _d ), in accordance with the relationship of (-0.00162 × ν _d +0.625) ≦ (θ g, F) ≦ (-0.00162 × ν _d +0.660); Chemical durability (acid resistance) is 1 to 5 grades.

(2) The optical glass according to (1), wherein the mass ratio Rn ₂ O / (P ₂ O ₅ + B ₂ O ₃ ) is less than 0.1, and Rn is one selected from the group consisting of Li, Na, and K the above.

(3) The optical glass according to (1) or (2), wherein the refractive index (n _d ) is 1.57 or more and 1.65 or less, and the Abbe number (ν _d ) is 50 or more and 70 or less.

(4) A preform made of the optical glass according to any one of (1) to (3).

(5) An optical element made of the optical glass according to any one of (1) to (3).

(6) An optical device including the optical element according to (5).

According to the present invention, it is possible to obtain an optical glass having good chemical durability (acid resistance) measured by the powder method and a relatively large partial dispersion.

FIG. 1 is a schematic diagram of a normal line represented by a rectangular coordinate with a partial dispersion ratio (θ g, F) as the vertical axis and an Abbe number (ν _d ) as the horizontal axis.

FIG. 2 is a schematic diagram showing a relationship between a partial dispersion ratio (θ g, F) and an Abbe number (ν _d ) according to an embodiment of the present invention.

The optical glass of the present invention contains 20.0% to 60.0% of P ₂ O ₅ component, 5.0% to 45.0% of BaO component, and more than 0% to 10.0% of Ln ₂ O ₃ component in terms of mass percentage; partial dispersion ratio (θ g, F ) And Abbe number (ν _d ), in accordance with the relationship of (-0.00162 × ν _d +0.625) ≦ (θ g, F) ≦ (-0.00162 × ν _d +0.660); chemical durability measured by powder method (Acid resistance) is 1 to 5 grades.

According to the present invention, by using a P ₂ O ₅ component as a main component and using a BaO component and a rare earth element component as essential components, a glass having good acid resistance as measured by the powder method and a relatively large partial dispersion can be obtained. .

Hereinafter, embodiments of the optical glass of the present invention will be described in detail, but the present invention is not limited to the following embodiments, and may be appropriately modified and implemented within the scope of the object of the present invention. In addition, although the description of the overlapping description may be appropriately omitted, it does not limit the gist of the invention.

[Glass composition]

The composition range of each component which comprises the optical glass of this invention is as follows. In the present specification, when the content of each component is not specifically denied, it is expressed in terms of mass% relative to the total mass of the glass in terms of oxide conversion composition. Here, the "oxide conversion composition" is assuming that the oxides, composite salts, metal fluorides, etc. used as the raw material of the glass constituents of the present invention are completely decomposed into oxides during melting, and the resulting oxides are formed. The total mass is set to 100% by mass to represent the composition of various components contained in the glass.

<About necessary ingredients and optional ingredients>

In the optical glass of the present invention, the P ₂ O ₅ component is an essential component, which is a main component for forming glass, and also a component that can improve glass viscosity and glass stability.

On the other hand, if the content of the P ₂ O ₅ component is too small, there may be a fear that the viscosity becomes lower as the glass becomes unstable, or there may be a concern that the stability of the glass is deteriorated. The content of the P ₂ O ₅ component in the optical glass is preferably 20.0% or more, more preferably 25.0% or more, and even more preferably 30.0% or more.

In addition, if the content of the P ₂ O ₅ component is too large, the refractive index will be reduced and the partial dispersion ratio will be reduced. Therefore, the content of the P ₂ O ₅ component is preferably 60.0% or less, more preferably 56.0% or less It is preferably 53.0% or less, and still more preferably 50.0% or less.

As the P ₂ O ₅ component system, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , H ₃ PO ₄ and the like can be used as raw materials.

The BaO component is an essential component of the present invention, and has the effect of increasing the refractive index of the glass and improving the stability of the glass, and can increase the partial dispersion ratio.

Therefore, the content of the BaO component is preferably 5.0% or more, more preferably 8.0% or more, and even more preferably 10.0% or more.

On the other hand, if the content of the BaO component is too large, the acid resistance will be deteriorated, and the linear expansion coefficient will be increased, making it difficult to become a glass with improved processability or a smaller linear expansion desired for the optical glass of the present invention. Therefore, the content of the BaO component is preferably 45.0% or less, more preferably 40.0% or less, and even more preferably 36.0% or less.

As the raw material for the BaO component system, BaCO ₃ , Ba (NO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BaF ₂ and the like can be used.

The sum (mass) of the content of the Ln ₂ O ₃ component (in the formula, Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) is preferably more than 0% and 15.0% or less.

In particular, by setting the mass sum to more than 0%, it is possible to have a desired refractive index while reducing the reduction rate of acid resistance in the powder method. The quality and content of the Ln ₂ O ₃ component content are preferably more than 0%, more preferably more than 1.0%, and even more preferably more than 3.0%.

On the other hand, by setting the mass sum to 15.0% or less, it is possible to prevent the partial dispersion ratio from becoming too small and improve the stability of the glass. Therefore, the mass and content of the content of the Ln ₂ O ₃ component is preferably 15.0% or less, more preferably 10.0% or less, and even more preferably 8.0% or less.

The mass ratio of the Rn ₂ O component (Rn is one or more selected from the group consisting of Li, Na, and K) to the sum of the P ₂ O ₅ component and the B ₂ O ₃ component is preferably less than 0.1.

By setting the ratio of Rn ₂ O / (P ₂ O ₅ + B ₂ O ₃ ) to an appropriate value, the decrease in the refractive index of the glass can be suppressed, and the glass can be stabilized, and the powder method can be made acid-resistant. The reduction rate becomes lower.

Therefore, Rn ₂ O / (P ₂ O ₅ + B ₂ O ₃ ) is preferably less than 0.1, more preferably less than 0.08, and more preferably less than 0.05.

The B ₂ O ₃ component is an optional component indispensable as a glass-forming oxide in the optical glass of the present invention containing a rare earth oxide. In particular, the optical glass of the present invention can improve the melting property of the glass by containing a B ₂ O ₃ component in excess of 0%. Therefore, the content of the B ₂ O ₃ component is preferably more than 0%, more preferably 3.0% or more, and even more preferably more than 5.0%.

On the other hand, when the content of the B ₂ O ₃ component is 20.0% or less, deterioration in chemical durability can be suppressed. Therefore, the content of the B ₂ O ₃ component is preferably 20.0% or less, more preferably 18.0% or less, and even more preferably less than 15.0%.

As the B ₂ O ₃ component system, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ ‧ 10H ₂ O, BPO ₄ and the like can be used as raw materials.

When the content of the SrO component system exceeds 0%, while maintaining the desired refractive index and dispersion, the partial dispersion ratio can also be increased.

On the other hand, if the content of the SrO component is too large, acid resistance is deteriorated, and the glass becomes unstable. Therefore, the content of the SrO component is preferably 35.0% or less, more preferably 30.0% or less, and even more preferably 28.0% or less.

As the SrO component system, Sr (NO ₃ ) ₂ , SrF ₂ , Sr (PO ₃ ) ₂ or the like can be used as a raw material.

The SiO ₂ component is an arbitrary component, and when the content exceeds 0%, the viscosity of the molten glass can be increased, and devitrification resistance can be improved.

On the other hand, by setting the content of the SiO ₂ component to 10.0% or less, stable glass can be obtained. Therefore, the content of the SiO ₂ component is preferably 10.0% or less, more preferably less than 5.0%, and even more preferably less than 3.0%.

As the SiO ₂ component system, SiO ₂ , K ₂ SiF ₆ , Na ₂ SiF _6, or the like can be used as a raw material.

The MgO component is an arbitrary component, and when its content exceeds 0%, the stability of the glass can be improved, and the partial dispersion ratio can be increased.

On the other hand, when the content of the MgO component is set to 15.0% or less, it is possible to reduce a decrease in refractive index or devitrification caused by an excessive content of these components. Therefore, the content of the MgO component is preferably 15.0% or less, more preferably less than 13.0%, and even more preferably less than 10.0%.

For the MgO component system, MgCO ₃ , MgF ₂ , MgO, and 4MgCO ₃ can be used. Mg (OH) ₂ and the like are used as raw materials.

The CaO component is an optional component, and when the content exceeds 0%, the meltability of the glass raw material or the devitrification resistance of the glass can be improved.

On the other hand, by reducing the content of the CaO component to 18.0% or less, it is possible to reduce a decrease in refractive index or devitrification caused by an excessive content of these components. The content of the CaO component is preferably 18.0% or less, more preferably less than 15.0%, and even more preferably less than 13.0%.

CaO component system may be used CaCO _3, CaF ₂ and the like as a raw material.

ZnO is an optional component, and when its content exceeds 0%, it can improve devitrification resistance, reduce specific gravity, and improve chemical durability. Therefore, the content of the ZnO component is preferably more than 0%, more preferably more than 0.5%, and even more preferably more than 1.0%.

On the other hand, by setting the content of the ZnO component to 20.0% or less, low dispersion can be maintained. Therefore, the content of the ZnO component is preferably 20.0% or less, more preferably 15.0% or less, more preferably 10.0% or less, and still more preferably 8.0% or less.

As the ZnO component system, ZnO, ZnF ₂ or the like can be used as a raw material.

The La ₂ O ₃ component is an optional component, and when the content exceeds 0%, the reduction rate of acid resistance can be reduced, and the refractive index can be increased. Therefore, the content of the La ₂ O ₃ component is preferably more than 0%, more preferably more than 0.5%, and even more preferably more than 1.0%.

On the other hand, if the content is too large, the devitrification resistance will be deteriorated, and the partial dispersion ratio will be small. Therefore, the content of the La ₂ O ₃ component is preferably 10.0% or less, more preferably 8.0% or less. It is preferably less than 5.0%.

La ₂ O ₃ component system can use La ₂ O ₃ and La (NO ₃ ) ₃ . XH ₂ O (X is an arbitrary integer) or the like is used as a raw material.

The Gd ₂ O ₃ component is an arbitrary component, and by setting the content to more than 0%, the devitrification resistance in the rare earth element is good, and the reduction rate of acid resistance can be reduced. Therefore, the content of the Gd ₂ O ₃ component is preferably more than 0%, more preferably more than 1.0%, and even more preferably more than 1.5%.

On the other hand, if the content is large, the devitrification resistance will be deteriorated, and the partial dispersion ratio will be small. Therefore, the content of the La ₂ O ₃ component is preferably 15.0% or less, more preferably 13.0% or less. It is preferably less than 8.0%.

As the Gd ₂ O ₃ component system, Gd ₂ O ₃ , GdF _3, or the like can be used as a raw material.

The Y ₂ O ₃ component and the Yb ₂ O ₃ component are arbitrary components. When the content of at least one of them exceeds 0%, the refractive index of the glass can be increased while maintaining the desired Abbe number, and devitrification resistance can be improved. .

On the other hand, by individually setting the content of the Y ₂ O ₃ component and the Yb ₂ O ₃ component to 10.0% or less, devitrification caused by an excessive content of these components can be reduced, and the material cost of the glass can be reduced. Therefore, the individual content of the Y ₂ O ₃ component and the Yb ₂ O ₃ component is preferably 10.0% or less, more preferably less than 5.0%, and even more preferably less than 3.0%.

As the Y ₂ O ₃ component and the Yb ₂ O ₃ component, Y ₂ O ₃ , YF ₃ , Yb ₂ O ₃ and the like can be used as raw materials.

The ZrO ₂ component is an optional component, and when the content exceeds 0%, the reduction rate of acid resistance can be reduced.

On the other hand, by setting the content of the ZrO ₂ component to be 10.0% or less, the desired Abbe number can be maintained, and deterioration in devitrification resistance due to excessive content of the ZrO ₂ component can be suppressed. Therefore, the content of the ZrO ₂ component is preferably 10.0% or less, more preferably less than 5.0%, and even more preferably less than 3.0%.

As the ZrO ₂ component system, ZrO ₂ , ZrF ₄ or the like can be used as a raw material.

The Nb ₂ O ₅ component is an arbitrary component, and when the content exceeds 0%, the acid resistance is improved, and the partial dispersion ratio is increased.

On the other hand, by setting the content of the Nb ₂ O ₅ component to 10.0% or less, the Abbe number can be kept low and the reduction rate of acid resistance can be reduced. Therefore, it is preferably 10.0% or less, and more preferably 8.0 % Or less, more preferably less than 5.0%, and even more preferably less than 3.0%.

As the Nb ₂ O ₅ component system, Nb ₂ O ₅ or the like can be used as a raw material.

The WO ₃ component is an arbitrary component, and when its content exceeds 0%, the refractive index and the partial dispersion ratio can be increased, and devitrification resistance can be improved.

On the other hand, by setting the content of the WO ₃ component to 10.0% or less, it is not easy to lower the transmittance of the glass with respect to visible light, and the material cost can be reduced. Therefore, the content of the WO ₃ component is preferably 10.0% or less, more preferably 8.0% or less, more preferably less than 5.0%, and still more preferably less than 3.0%.

As the WO ₃ component system, WO ₃ or the like can be used as a raw material.

The TiO ₂ component is an arbitrary component, and when the content exceeds 0%, the reduction rate of acid resistance can be reduced, and the partial dispersion ratio can be increased.

On the other hand, by setting the content of the TiO ₂ component to 10.0% or less, a stable Abbe number can be maintained and a stable glass can be obtained. Therefore, the content of the TiO ₂ component is preferably 10.0% or less, more preferably less than 5.0%, and even more preferably less than 3.0%.

As the TiO ₂ component system, TiO ₂ or the like can be used as a raw material.

The Ta ₂ O ₅ component is an arbitrary component, and when the content exceeds 0%, the refractive index can be increased, the devitrification resistance can be improved, and the viscosity of the molten glass can be improved.

On the other hand, by setting the content of the Ta ₂ O ₅ component to 5.0% or less, the amount of the Ta ₂ O ₅ component used in the rare mineral resource can be reduced, and the material cost of glass can be reduced. Therefore, the content of the Ta ₂ O ₅ component is preferably 5.0% or less, more preferably less than 3.0%, more preferably less than 1.0%, and most preferably not contained.

As the Ta ₂ O ₅ component system, Ta ₂ O ₅ or the like can be used as a raw material.

The Li ₂ O component is an arbitrary component, and when the content exceeds 0%, the melting property of the glass can be improved and the refractive index can be increased. Therefore, the content of the Li ₂ O component is preferably more than 0%, more preferably more than 0.5%, and even more preferably more than 1.0%.

On the other hand, by setting the content of the Li ₂ O component to 10.0% or less, devitrification can be reduced and the viscosity of the glass can be improved, so that the occurrence of glass texture can be reduced. Therefore, the content of the Li ₂ O component is preferably 10.0% or less, more preferably less than 8.0%, more preferably less than 5.0%, and even more preferably less than 3.0%.

As the Li ₂ O component system, Li ₂ CO ₃ , LiNO ₃ , Li ₂ F, or the like can be used as a raw material.

The Na ₂ O component and the K ₂ O component are arbitrary components, and when the content of at least one of them exceeds 0%, the melting property of the glass raw material can be improved, and devitrification resistance can be improved.

On the other hand, when the individual content of the Na ₂ O component and the K ₂ O component is set to 10.0% or less, the refractive index is not easily reduced, and devitrification due to excessive content can be reduced. Therefore, the individual content of the Na ₂ O component and the K ₂ O component is preferably 10.0% or less, more preferably less than 8.0%, more preferably less than 5.0%, and even more preferably less than 3.0%.

As Na ₂ O component and K ₂ O component system, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ , K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ and the like can be used as raw materials.

The GeO ₂ component is an arbitrary component. When the content exceeds 0%, the refractive index of glass can be increased, and devitrification resistance can be improved.

However, since the raw materials of GeO ₂ are expensive, if the amount of GeO ₂ used is too large, the material cost will increase. Therefore, the content of the GeO ₂ component is preferably 10.0% or less, more preferably less than 5.0%, more preferably less than 3.0%, even more preferably less than 1.0%, and most preferably not contained.

As the GeO ₂ component system, GeO ₂ or the like can be used as a raw material.

The Al ₂ O ₃ component is an optional component, and when the content exceeds 0%, it can reduce the acid resistance reduction rate and improve the devitrification resistance. Therefore, the content of the Al ₂ O ₃ component is preferably more than 0%, more preferably more than 0.5%, and even more preferably more than 1.0%.

On the other hand, by setting the content of the Al ₂ O ₃ component to 10.0% or less, devitrification due to excessive content can be reduced. Therefore, the content of the Al ₂ O ₃ component is preferably 10.0% or less, more preferably less than 9.0%, and even more preferably less than 8.0%.

As the Al ₂ O ₃ component system, Al ₂ O ₃ , Al (OH) ₃ , AlF _3, or the like can be used as a raw material.

The Ga ₂ O ₃ component is an arbitrary component, and when at least one of them contains more than 0%, chemical durability and devitrification resistance can be improved.

On the other hand, by setting the content of the Ga ₂ O ₃ component to 10.0% or less, devitrification due to excessive content can be reduced. Therefore, the content of the Ga ₂ O ₃ component is preferably 10.0% or less, more preferably less than 5.0%, more preferably less than 3.0%, and even more preferably less than 1.0%.

As the Ga ₂ O ₃ component system, Ga ₂ O ₃ or the like can be used as a raw material.

The Bi ₂ O ₃ component is an arbitrary component, and when its content exceeds 0%, the refractive index can be increased, the Abbe number can be reduced, and the glass transition point can be reduced.

On the other hand, by setting the content of the Bi ₂ O ₃ component to 10.0% or less, the devitrification resistance of the glass can be improved, and the coloration of the glass can be reduced to increase the visible light transmittance. Therefore, the content of the Bi ₂ O ₃ component is preferably 10.0% or less, more preferably less than 5.0%, more preferably less than 3.0%, and even more preferably less than 1.0%.

As the Bi ₂ O ₃ component system, Bi ₂ O ₃ or the like can be used as a raw material.

The TeO ₂ component is an arbitrary component. When the content exceeds 0%, the refractive index can be increased and the glass transition point can be reduced.

On the other hand, by setting the content of the TeO ₂ component to 10.0% or less, it is possible to reduce the coloration of the glass and improve the visible light transmittance. In addition, when a glass raw material is melted in a crucible made of platinum or in a melting tank made of platinum in a portion in contact with the molten glass, there is a problem that TeO ₂ may alloy with platinum. Therefore, the content of the TeO ₂ component is preferably 10.0% or less, more preferably less than 5.0%, more preferably less than 3.0%, and even more preferably less than 1.0%.

As the TeO ₂ component system, TeO ₂ or the like can be used as a raw material.

The SnO ₂ component is an arbitrary component, and when the content exceeds 0%, it can reduce the oxidation of the molten glass, while suppressing the dissolution of platinum, and promoting the clearness of the molten glass.

On the other hand, by setting the content of the SnO ₂ component to 3.0% or less, it is possible to reduce glass coloration or devitrification of the glass caused by reduction of the molten glass. In addition, since the alloying between the SnO ₂ component and the melting equipment (especially, noble metals such as Pt) is reduced, the useful life of the melting equipment can be expected to be extended. Therefore, the content of the SnO ₂ component is preferably 3.0% or less, more preferably less than 1.0%, and even more preferably less than 0.5%.

As the SnO ₂ component system, SnO, SnO ₂ , SnF ₂ , SnF ₄ and the like can be used as raw materials.

The Sb ₂ O ₃ component is an arbitrary component, and when the content thereof exceeds 0%, the molten glass can be defoamed.

On the other hand, if the content of the Sb ₂ O ₃ component is too large, the transmittance in the short wavelength range of the visible light range is deteriorated. Therefore, the content of the Sb ₂ O ₃ component is preferably 1.0% or less, more preferably less than 0.5%, and even more preferably less than 0.1%.

As the Sb ₂ O ₃ component system, Sb ₂ O ₃ , Sb ₂ O ₅ , and Na ₂ H ₂ Sb ₂ O ₇ can be used. 5H ₂ O and the like are used as raw materials.

In addition, clear and defoaming of the glass component, not limited to the Sb ₂ O ₃ ingredients may be used in the manufacture of glass well-known in the art fining agents, antifoaming agents, or a combination of these.

The F component is an arbitrary component, and when its content exceeds 0%, the Abbe number of glass can be increased, the glass transition point can be reduced, and devitrification resistance can be improved.

However, if the content of the F component, that is, the total amount of F of some or all of the fluorides that replace one or more of the oxides of the above elements, exceeds 10.0%, the volatile content of the F component will increase, so It may become difficult to obtain a stable optical constant, and it may be difficult to obtain a homogeneous glass. In addition, the Abbe number will rise above what is needed. Therefore, the content of the F component is preferably 10.0% or less, more preferably less than 5.0%, more preferably less than 3.0%, still more preferably less than 1.0%, and still more preferably no content.

The F component can be contained in glass by using, for example, ZrF ₄ , AlF ₃ , NaF, CaF ₂ or the like as a raw material.

The total (mass) of the content of the RO component (R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably 10.0% or more and 50.0% or less.

In particular, by setting the total to 10.0% or more, the refractive index can be increased and the devitrification resistance of the glass can be improved. Therefore, the total content of the RO component is preferably 10.0% or more, more preferably 15.0% or more, more preferably 20.0% or more, still more preferably 25.0% or more, and still more preferably 28.0% or more.

On the other hand, by setting the total to 50.0% or less, devitrification caused by an excessive content of these components can be reduced, and glass having a low acid resistance reduction rate or low abrasion can be obtained. Therefore, the total content of the RO component is preferably 50.0% or less, more preferably less than 48.0%, and even more preferably less than 45.0%.

The sum (mass) of the content of the Rn ₂ O component (Rn is one or more selected from the group consisting of Li, Na, and K) is preferably 10.0% or less. This makes it possible to suppress a decrease in the refractive index of the glass and reduce devitrification. Therefore, the lower limit of the Rn ₂ O component system is preferably more than 0%, more preferably more than 0.05%, and even more preferably more than 0.10%.

Therefore, the mass and content of the Rn ₂ O component content is preferably 10.0% or less, more preferably less than 8.0%, more preferably less than 5.0%, and even more preferably less than 3.0%.

The mass ratio of the ZnO component to the BaO component is preferably 0.01 or more. Thereby, a linear expansion coefficient can be made small. The mass ratio (ZnO / BaO) is preferably 0.01 or more, more preferably 0.025 or more, more preferably 0.05 or more, and still more preferably more than 0.1.

On the other hand, by setting the mass ratio (ZnO / BaO) to 1.0 or less, it is possible to maintain a desired refractive index while maintaining low dispersion. Therefore, the upper limit of the mass ratio (ZnO / BaO) is preferably 1.0 or less, more preferably 0.8 or less, and even more preferably 0.5 or less.

The sum (mass sum) of the P ₂ O ₅ component and the B ₂ O ₃ component is preferably 30.0% or more. Thereby, the glass can be stabilized, and it becomes easy to introduce a component that improves the acid resistance of the powder method, or a component that increases the partial dispersion ratio. The mass and ratio of P ₂ O ₅ and B ₂ O ₃ are preferably 30.0% or more, more preferably 35.0% or more, and still more preferably 40.0% or more.

On the other hand, if the mass is too large, it becomes difficult to obtain the desired refractive index and Abbe number. Therefore, it is preferably less than 65.0%, more preferably less than 63.0%, and even more preferably less than 60.0. %, More preferably less than 56.0%.

By setting the mass ratio of the SrO component to the BaO component to be 2.00 or less, the reduction rate of acid resistance in the powder method can be reduced, and the linear expansion coefficient can be made small. Therefore, the upper limit of the mass ratio (SrO / BaO) is preferably 2.00 or less, more preferably 1.80 or less, and even more preferably 1.60 or less.

The sum (mass sum) of the content of the La ₂ O ₃ component and the Gd ₂ O ₃ component is preferably more than 0%. This makes it possible to obtain a glass having good acid resistance by the powder method. Therefore, the quality sum is preferably more than 0%, more preferably more than 1.0%, and even more preferably more than 3.0%.

On the other hand, the mass sum (La ₂ O ₃ + Gd ₂ O ₃ ) is preferably less than 15.0%. If it contains 15.0% or more, devitrification property will deteriorate and it will become difficult to obtain a stable glass. Therefore, the quality sum is preferably less than 15.0%, more preferably less than 13.0%, and even more preferably less than 8.0%.

The mass ratio of the SrO component, the CaO component, and the MgO component to the BaO component is preferably 0.20 or more. Thereby, the reduction rate of acid resistance in the powder method can be reduced, and the linear expansion coefficient can be made small. Therefore, the mass ratio is preferably 0.20 or more, more preferably 0.22 or more, and still more preferably 0.24 or more.

On the other hand, by setting the mass ratio (SrO + CaO + MgO) / BaO to 3.00 or less, it is possible to keep the glass stable while having a desired refractive index. Therefore, the mass ratio is preferably 3.00 or less, more preferably 2.50 or less, and even more preferably 2.20 or less.

<About ingredients that should not be contained>

Next, components which should not be contained in the optical glass of the present invention and components which should not be contained are described.

As long as the glass characteristics of the present invention are not impaired, other components may be added as required. However, in addition to Ti, Zr, Nb, W, La, Gd, Y, Yb, Lu, V, Cr, Mn, Fe, Co, Ni, Cu, Ag, Mo and other various transition metal components are separately or When it is contained in a composite form, even if it is contained in a small amount, the glass may be colored, and the property of absorbing light of a specific wavelength in the visible range may occur. Therefore, it is particularly preferable for optical glass using a wavelength in the visible range. It does not contain substantially.

In addition, since lead compounds such as PbO and arsenic compounds such as As ₂ O ₃ are components having a high environmental load, they are preferably substantially not contained, that is, they are completely contained except for unavoidable mixing.

Furthermore, the components Th, Cd, Tl, Os, Be, and Se have been regarded as harmful chemical substances in recent years, and there is a tendency to avoid use, not only in the glass manufacturing steps, but also in the processing steps and after productization. Environmental measures must be taken up to the time of disposal. Therefore, from the viewpoint of attaching importance to environmental impact, it is preferable that these components are not substantially contained.

[Production method]

The optical glass of this invention can be manufactured as follows, for example. That is, each component is uniformly mixed within the specified content range, and the prepared mixture is put into a platinum crucible, a quartz crucible or an alumina crucible for preliminary melting, and then put into the platinum crucible and platinum. Melt in an alloy crucible or an iridium crucible at a temperature range of 1100 ° C to 1400 ° C for 1 hour to 5 hours, stir to homogenize and defoam, and then cool to 900 ° C to 1300 ° C. The agitation in the final stage removes the texture, and then casts it into a mold, and then cools it slowly to produce the optical glass of the present invention.

[Physical properties]

The optical glass system of the present invention has a desired refractive index and a high Abbe number (low dispersion).

In particular, the lower limit of the refractive index (n _d ) of the optical glass of the present invention is preferably 1.57 or more, more preferably 1.58 or more, and even more preferably 1.59 or more.

On the other hand, the upper limit of the refractive index is preferably 1.65 or less, more preferably 1.64, and even more preferably 1.63. The lower limit of the Abbe number (ν _d ) of the optical glass of the present invention is preferably 50 or more, more preferably 52 or more, and even more preferably 54 or more. The upper limit of the Abbe number is preferably 70 or less, more preferably less than 68, and more preferably 65 or less.

Since the optical glass of the present invention has such a refractive index and Abbe number, it can play an effect in optical design. In particular, while a high degree of imaging characteristics is desired, the optical system can be miniaturized and can be expanded. Freedom of optical design.

The optical glass of the present invention preferably has a high partial dispersion ratio (θ g, F).

More specifically, the partial dispersion ratio (θ g, F) of the optical glass of the present invention, and its relationship with the Abbe number (ν _d ), preferably conform to (-0.00162 × ν _d +0.625) ≦ ( θ g, F) ≦ (-0.00162 × ν _d +0.660).

In this way, the optical glass of the present invention has a higher partial dispersion ratio (θ g, F) even when compared to a glass that is conventionally known to contain many rare earth element components. Therefore, while high refractive index and low dispersion of glass can be expected, the optical element formed from the optical glass can also be applied to correction of chromatic aberration.

Here, the partial dispersion optical glass of the present invention, the ratio (θ g, F) to the lower limit line (-0.00162 × ν _d +0.625) better, preferably (-0.00162 × ν _d +0.630), more preferably ( -0.00162 × ν _d +0.632).

On the other hand, the upper limit of the partial dispersion ratio (θ g, F) of the optical glass of the present invention is usually (-0.00162 × ν _d +0.660) or less, more specifically (-0.00162 × ν _d + 0.658) or less, More specifically, it is (-0.00162 × ν _d +0.656) or less. As long as the partial dispersion ratio (θ g, F) and Abbe number (ν _d ) of the glass of the specific composition in the present invention satisfy this relationship, a stable glass can be obtained.

The optical glass of the present invention preferably has high acid resistance. In particular, the chemical durability (acid resistance) measured by the glass powder method of JOGIS06-2009 is preferably 5 or more, more preferably 4 or more, and even more preferably 3 or more.

The term "acid resistance" as used herein refers to the durability of glass corrosion due to acid. The acid resistance can be determined by the Japan Optical Glass Industry Standard JOGIS06-2009 "chemical durability of optical glass (powder method). ) ". In addition, "chemical durability (acid resistance) measured by the powder method is grades 1 to 3" means that chemical durability (acid resistance) according to JOGISO6-2009 is based on the mass reduction rate of samples before and after the measurement, It is less than 0.65 mass%.

In addition, "level 1" of chemical durability (acid resistance) means that the weight loss rate of samples before and after the measurement is less than 0.20% by mass, and "level 2" means that the weight loss rate of samples before and after the measurement is 0.20% by mass or more. 0.35 mass% or more, "level 3" means that the weight loss rate of the sample before and after the measurement is 0.35 mass% or more and less than 0.65 mass%, and "level 4" means that the weight loss rate of the sample before and after measurement is 0.65 mass% When it is over 1.20% by mass, "level 5" means that the weight loss rate of the sample before and after the measurement is 1.20% by mass or more and less than 2.20% by mass, and "level 6" means that the weight loss rate of the sample before and after the measurement is 2.20% by mass or more.

The average linear thermal expansion coefficient α of the optical glass of the present invention from 100 ° C. to 300 ° C. is preferably 130 (10 ^-7 ° C. ^-1 ) or less.

That is, the upper limit of the average linear thermal expansion coefficient α of the optical glass of the present invention from 100 ° C. to 300 ° C. is preferably 130 or less, more preferably 125 (10 ^-7 ° C. ^-1 ) or less, and more preferably 120 or less.

The optical glass of the present invention has a high visible light transmittance, and particularly a high transmittance of light on the short wavelength side of visible light, thereby making the coloring situation less, so it is preferable.

In particular, if the optical glass of the present invention is expressed in terms of glass transmittance, in the case of a 10 mm thick sample, the upper limit of the wavelength (λ ₈₀ ) indicating a spectral transmittance of 80% is preferably 420 nm, more preferably 400 nm, More preferably, it is 380 nm.

In addition, in the optical glass of the present invention, in the case of a 10-mm-thick sample, the upper limit of the shortest wavelength (λ ₅ ) representing a spectral transmittance of 5% is preferably 380 nm, more preferably 370 nm, and more preferably 360 nm.

With this, the absorption end of the glass is located near the ultraviolet light field, which can improve the transparency of the glass to visible light. Therefore, the optical glass can be applied to an optical element such as a lens that allows light to pass through.

[Glass molded body and optical element]

The glass formed body can be produced from the produced optical glass by a method such as a grinding process or a press forming method such as reheat press forming or precision press forming. That is, a glass shaped body can be produced in the following manner: a glass shaped body is produced by mechanical processing such as grinding and grinding of optical glass; a pre-formed body made of optical glass is subjected to reheat pressing, and then Grinding is performed to produce a glass formed body; preforms produced by performing a grinding process, or preforms formed by a known floating molding or the like are subjected to precision press molding to produce a glass formed body or the like. However, the method of manufacturing a glass forming body is not limited to the above-mentioned methods.

In this way, the glass molded body formed from the optical glass of the present invention can exert its effects on a variety of optical elements and optical designs, and among them, it is particularly desirable to be used for optical elements such as lenses and lenses. As a result, a large-sized glass molded body can be formed. Therefore, while the size of the optical element can be expected, it can also achieve high-definition and high-precision imaging characteristics when used in optical equipment such as cameras and projectors. Projection characteristics.

[Example]

Compositions of Examples (No. 1 to No. 32) of the present invention and Comparative Examples A and B, refractive index (n _d ), Abbe number (ν _d ), partial dispersion ratio (θ g, F), acid resistance The linear expansion coefficient (100 to 300 ° C) of the glass and the wavelengths (λ ₅ , λ ₈₀ ) indicating the spectral transmittances of 5% and 80% are shown in Tables 1 to 3.

In addition, the following examples are for illustrative purposes only, and the present invention is not limited to these examples.

The raw materials of the glass-based components of the examples and comparative examples of the present invention are selected from the oxides, hydroxides, carbonates, nitrates, fluorides, meta-acid compounds and other high-purity glasses used in accordance with the raw materials. The raw materials are then weighed and uniformly mixed with the composition ratios of the respective examples and comparative examples shown in the table, and then put into a quartz crucible or a platinum crucible, and according to the melting difficulty of the glass composition, In an electric furnace at a temperature range of 1100 ° C to 1400 ° C, melt for 1 hour to 5 hours, and then stir to homogenize and defoam, and then reduce the temperature to 1000 ° C to 1300 ° C. Stir to homogenize. It is cast into a mold and slowly cooled to make glass.

The glass refractive index (n _d ) and Abbe number (ν _d ) of the examples and comparative examples are represented by measured values with respect to the d-line (587.56 nm) of the helium lamp. In addition, the Abbe number (ν _d ) is the refractive index (n _F ) with respect to the F-line (486.13 nm) of the hydrogen lamp, and the refraction with respect to the C-line (656.27 nm) using the above-mentioned d-line. The numerical value of the rate (n _C ) is calculated from the Abbe number (ν _d ) = [(n _d -1) / (n _F -n _C )].

In addition, the partial dispersion ratio is a measurement of the refractive index n _{C in the C-} line (wavelength 656.27 nm), the refractive index n _{F in the F-} line (wavelength 486.13 nm), and the refractive index n in the g-line (wavelength 435.835 nm). _g , and then calculate the dispersion ratio of this part by the formula of (θ g, F) = (n _g -n _F ) / (n _F -n _C ).

In addition, the acid resistance of the glass of the Example and the comparative example was measured based on the Japan Optical Glass Industry Association standard "Measurement method of chemical durability of optical glass (powder method)" JOGIS06-2009. That is, a glass sample that has been pulverized to a particle size of 425 μm to 600 μm is weighed by the specific gravity grams, and then placed in a platinum cage. This platinum cage was placed in a round bottom flask made of quartz glass to which a 0.01 N nitric acid aqueous solution was added, and subjected to a boiling water bath treatment for 60 minutes. Calculate the weight loss rate (mass%) of the processed glass sample. The weight loss rate (mass%) is level 1 when it is less than 0.20, and it is grade 2 when the weight loss rate is 0.20 to less than 0.35. Level 3, with a reduction rate of 0.65 to less than 1.20, level 4; a reduction rate of 1.20 to less than 2.20, level 5; and a reduction rate of 2.20 or more, level 6. In this case, the smaller the number of stages, the better the acid resistance of the glass.

In addition, the coefficients of linear expansion of glass (100 ° C to 300 ° C) in the examples and comparative examples are based on the JOGIS08-2003 "Measurement Method for Thermal Expansion of Optical Glass" by the Japan Optical Glass Industry Association. This measurement is performed to obtain a thermal expansion curve, and a linear expansion coefficient is obtained from the thermal expansion curve.

The glass transmittances of the examples and comparative examples were measured in accordance with the standards of the Japan Optical Glass Industry Association JOGIS02-2003. In addition, in the present invention, by measuring the transmittance of the glass, the presence or absence of coloring of the glass and the degree of coloring thereof can be determined. Specifically, λ ₅ (wavelength at a transmittance of 5%) and λ ₈₀ (transmittance) are obtained by measuring a spectroscopic transmittance of 200 to 800 nm in accordance with JISZ8722 with a parallel-faced abrasive product having a thickness of 10 ± 0.1 mm. Wavelength at 80%).

As shown in the table, the refractive index (n _d ) of the optical glass according to the embodiment of the present invention is 1.57 or more, and the refractive index (n _d ) is 1.65 or less, which are all within the desired range.

In addition, the optical glass of the embodiment of the present invention has an Abbe number (ν _d ) of 50 or more, and the Abbe number (ν _d ) of 70 or less, which are all within a desired range.

In addition, no matter what the optical glass of the embodiment of the present invention, the partial dispersion ratio (θ g, F) and the Abbe number (ν _d ) are in accordance with (-0.00162 × ν _d +0.625) ≦ (θ g, F ) ≦ (-0.00162 × ν _d +0.660).

In addition, the optical glass of the embodiment of the present invention has an acid resistance of 5 or higher. On the other hand, the optical resistance of the optical glass of Comparative Example A was Grade 6, and it was clear that it was a glass with poor workability.

In addition, no matter what the optical glass of the embodiment of the present invention is, its glass linear expansion coefficient (100 ° C to 300 ° C) is 130 or less.

In addition, λ ₈₀ (wavelength at 80% transmittance) of the optical glass of the embodiment of the present invention is 420 nm or less. In addition, λ ₅ (wavelength at a transmittance of 5%) of the optical glass according to the embodiment of the present invention is 380 nm or less. Therefore, it is clear that the optical glass according to the embodiment of the present invention has high transmittance to visible light and is difficult to color.

In addition, the optical glass of the embodiment of the present invention is not devitrified and is a stable glass.

On the other hand, since the optical glass B of the comparative example may be devitrified, it is not vitrified.

Therefore, it can be clearly known that the partial dispersion ratio (θ g, F) and the Abbe number (ν _d ) of the optical glass according to the embodiment of the present invention is (-0.00162 × ν _d +0.625) ≦ (θ g , F) ≦ (-0.00162 × ν _d +0.660), and can obtain optical glass with acid resistance of 3 to 5 grade.

In the above, although the present invention has been described in detail with the purpose of illustration, the purpose of this embodiment is merely for illustration, and it should be fully understood that the person with ordinary knowledge in the technical field can be understood without departing from the spirit and scope of the present invention Many changes can be made to the present invention.

Claims (6)

An optical glass, based on mass%, containing: 20.0% to 60.0% of P ₂ O ₅ component; 5.0% to 45.0% of BaO component; and more than 0% to 15.0% of Ln ₂ O ₃ component; partial dispersion of the aforementioned optical glass The ratio (θ g, F) and the Abbe number (ν _d ) are in accordance with the relationship of (-0.00162 × ν _d +0.625) ≦ (θ g, F) ≦ (-0.00162 × ν _d +0.660); the aforementioned optics The chemical durability, that is, the acid resistance of glass measured by the powder method, is grades 1 to 5. The optical glass according to claim 1, wherein the mass ratio Rn ₂ O / (P ₂ O ₅ + B ₂ O ₃ ) is less than 0.1, and Rn is one or more selected from the group consisting of Li, Na, and K. . The optical glass according to claim 1 or 2, wherein the refractive index (n _d ) is 1.57 or more and 1.65 or less, and the Abbe number (ν _d ) is 50 or more and 70 or less.     A preform made of the optical glass according to any one of claims 1 to 3.         An optical element made of the optical glass according to any one of claims 1 to 3.         An optical device includes the optical element according to claim 5.