CN110937809A

CN110937809A - Optical glass, optical element and preformed body

Info

Publication number: CN110937809A
Application number: CN201911200872.1A
Authority: CN
Inventors: 前川公贵; 吉川健
Original assignee: Ohara Inc
Current assignee: Ohara Inc
Priority date: 2012-05-15
Filing date: 2013-05-14
Publication date: 2020-03-31
Also published as: CN103420611A; JP2013256439A; TW201400431A; TWI564263B

Abstract

The present invention provides an optical glass, which can reduce glass breakage or cracking during press molding and can improve the productivity of an optical element, a maximum value (α) of a linear expansion coefficient in a temperature range between a glass transition temperature (Tg) and a yield point (At) of the optical glass, an optical element, and a preform and an optical element using the optical glass_max) Is 1500 multiplied by 10^‑7K^‑1The following. The optical glass may contain P⁵⁺、Al³⁺And Ca²⁺As a cationic component, contains O^2‑And F^‑An optical glass as an anionic component.

Description

Optical glass, optical element and preformed body

The present application is a divisional application of patent application "optical glass, optical element and preform" having application number 201310187148.6, application number 2013, 5, 14.

Technical Field

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

Background

In recent years, digitalization and high precision of devices using optical systems have been rapidly advanced, and demands for high precision, light weight, and miniaturization of optical elements such as lenses used in various optical devices including imaging devices such as digital cameras and video cameras have been strong.

In particular, since the production of an aspherical lens by grinding and polishing methods is costly and inefficient, a glass preform or a glass block is cut and polished as a method for producing an aspherical lens, the resulting preform material is softened by heating, and is subjected to pressure molding using a molding die having a highly accurate surface, thereby omitting the grinding and polishing steps and realizing low-cost and mass production.

As the optical glass used for the press molding, for example, a glass represented by patent document 1 is known.

Patent document 1: japanese laid-open patent publication No. 2002-234753

Disclosure of Invention

However, in the optical glass described in patent document 1, glass breakage or cracking often occurs when pressure molding is performed. Here, glass that is cracked or cracked after press molding has not been used as an optical element. Therefore, it is desired to develop an optical glass which reduces cracking or crazing at the time of press molding.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical glass capable of reducing breakage or cracking of the glass at the time of press molding and improving productivity of an optical element, and a preform and an optical element using the same.

The present inventors have made extensive and intensive studies to solve the above problems, and as a result, have found that: by using the glass transition temperature (Tg) and flexorMaximum value (α) of the linear expansion coefficient in the temperature range between service points (At)_max) Small optical glass, which can reduce the breakage or cracking of glass during press molding, has been completed. Specifically, the present invention provides the following.

(1) An optical glass having a maximum value (α) of a linear expansion coefficient in a temperature range between a glass transition temperature (Tg) and a yield point (At)_max) Is 1500 multiplied by 10^-7K^-1The following.

(2) The optical glass as described in (1), wherein Pp is contained⁵⁺、Α1³⁺And Ca²⁺As a cationic component, O is contained^2-And F^-As the anionic component.

(3) The optical glass as described in (1) or (2), wherein the glass contains 15.0 to 55.0% of Pp in terms of cation% (mol%) (ii)⁵⁺5.0 to 30.0% of Al³⁺And 0.1 to 35.0% of Ca²⁺。

(4) The optical glass according to any one of (1) to (3), wherein the glass is a glass having a glass composition which, in terms of cation% (mol%),

Mg²⁺the content of (B) is0 to 20.0%,

Li⁺the content of (B) is0 to 10.0%.

(5) The optical glass as described in any of (1) to (4), wherein Mg²⁺Content and Li⁺The total content (cation%) is 20.0% or less.

(6) The optical glass as described in any one of (1) to (5), expressed as anion% (mol%),

F^-the content of (B) is 30.0 to 80.0%,

O^2-the content of (B) is 20.0 to 70.0%.

(7) The optical glass according to any one of (1) to (6), wherein the glass is a glass having a glass transition temperature, in terms of cation% (mol%),

Sr²⁺the content of (B) is0 to 30.0%,

Ba²⁺the content of (B) is0 to 30.0%.

(8) The optical system of any one of (1) to (7)Glass of which Sr²⁺Content and Ba²⁺The total content of Mg²⁺Content and Li⁺The total ratio of the contents (Sr)²⁺+Ba²⁺)/(Mg²⁺+Li⁺) Is 10.0 or less.

(9) The optical glass according to any one of (1) to (8), wherein the glass is selected from Mg²⁺、Ca²⁺、Sr²⁺And Ba²⁺Total content (R) of at least 1 species of (A)²⁺: cation%) is 30.0-70.0%.

(10) The optical glass as described in any one of (1) to (9), wherein Ca²⁺Relative to the content of Mg²⁺、Ca²⁺、Sr²⁺And Ba²⁺Total content (R) of at least 1 species of (A)²⁺: cation%) ratio (Ca)²⁺/R²⁺) Is 0.10 or more.

(11) The optical glass according to any one of (1) to (10), wherein the glass is a glass having a glass transition temperature, in terms of cation% (mol%),

La³⁺the content of (B) is0 to 10.0%,

Gd³⁺the content of (B) is0 to 10.0%,

Y³⁺the content of (B) is0 to 10.0%,

Yb³⁺the content of (B) is0 to 10.0%.

(12) The optical glass according to any one of (1) to (11), wherein La is selected from the group consisting of³⁺、Gd³⁺、Y³⁺And Yb³⁺Total content (Ln) of at least 1 species of (A)³⁺: cation%) is0 to 20.0%.

(13) The optical glass according to any one of (1) to (12), wherein the glass is a glass having a glass transition temperature, in terms of cation% (mol%),

Na⁺the content of (B) is0 to 10.0%,

K⁺the content of (B) is0 to 10.0%.

(14) The optical glass as described in any one of (1) to (13), wherein Li is selected⁺、Na⁺And K⁺Total content (Rn) of at least 1 species of (A)⁺: cation%) is 20.0% or less.

(15) The optical glass according to any one of (1) to (14), wherein the glass is a glass having a glass composition which, in terms of cation% (mol%),

Si⁴⁺the content of (B) is0 to 10.0%,

B³⁺the content of (B) is0 to 15.0%,

Zn²⁺the content of (B) is0 to 30.0%,

Ti⁴⁺the content of (B) is0 to 10.0%,

Nb⁵⁺the content of (B) is0 to 10.0%,

W⁶⁺the content of (B) is0 to 10.0%,

Zr⁴⁺the content of (B) is0 to 10.0%,

Ta⁵⁺the content of (B) is0 to 10.0%,

Ge⁴⁺the content of (B) is0 to 10.0%,

Bi³⁺the content of (B) is0 to 10.0%,

Te⁴⁺the content of (B) is0 to 15.0%.

(16) An optical element formed of the optical glass described in any one of (1) to (15).

(17) A preform for use in polishing and/or precision press molding, which is formed from the optical glass according to any one of (1) to (15).

(18) An optical element formed by precisely pressing the preform of (17).

According to the present invention, since breakage or cracking is less likely to occur in the glass after press molding, it is possible to provide an optical glass capable of improving the productivity of an optical element, and a preform and an optical element using the same.

Detailed Description

For the optical glass of the present invention, the maximum value (α) of the linear expansion coefficient in the temperature range between the glass transition temperature (Tg) and the yield point (At)_max) Is 1500 multiplied by 10^-7K^-1The following. Thus, even if the glass is heated to a temperature higher than the glass transition temperature and press-molded, the glass after press-molding is hard to break and hard to be pressedCracks are formed. Therefore, it is possible to reduce the occurrence of cracks or flaws particularly in the step of press-molding the glass in the step of manufacturing the optical element, and thereby to improve the productivity of the optical element.

The optical glass of the present invention will be explained below. The present invention is not limited to the following embodiments, and can be implemented by appropriately changing the configuration within the scope of the object of the present invention. Note that, although the description may be omitted where the description is repeated, the invention is not limited thereto.

< glass composition >

By maximizing the linear expansion coefficient (α) in the temperature range between the glass transition temperature (Tg) and the yield point (At) of the optical glass of the present invention_max) The composition is not limited to the above composition per se because the desired problems can be solved by the following method. That is, the glass is not limited to the specific fluorophosphate glass below, for example, even if B is contained₂O₃、SiO₂Or P₂O₅Etc. as the glass constituent component, if the glass has a desired maximum value of the linear expansion coefficient (α)_max) And is also included in the optical glass of the invention of the present application.

Among them, the present inventors have found that: in the presence of P⁵⁺、Al³⁺And Ca²⁺As a cationic component, contains O^2-And F^-The fluorophosphate glass as an anionic component is obtained by containing Ca in particular²⁺As a cationic component, contains O^2-The anion component may have a maximum value of linear expansion coefficient of not more than a predetermined value.

That is, as the optical glass of the present invention, the above fluorophosphate glass is preferably used. This makes it possible to obtain a glass having a small maximum value of linear expansion coefficient, and thus it is possible to reduce cracking or fissures in the glass after press molding.

Hereinafter, each component constituting the fluorophosphate glass which is preferably used as a glass having a maximum value of a linear expansion coefficient of not more than a predetermined value will be described.

In the present specification, when the content of each component is not particularly described, all of the contents are expressed as cation% or anion% based on a molar ratio. Here, "cation%" and "anion%" (hereinafter sometimes referred to as "cation% (mol%)" and "anion% (mol%)") are compositions in which the glass constituent components of the optical glass of the present invention are divided into cation components and anion components, and the content of each component contained in the glass is represented by assuming that the total ratio of the cation components and the total ratio of the anion components are 100 mol%, respectively.

Note that, for convenience, the ion valences of the respective components are not distinguished from other ion valences because only representative values are used. The ion valence of each component present in the optical glass may be an ion valence other than the representative value. For example, since P is usually present in the glass in a state of ionic valence of 5, it is represented as "P" in the present specification⁵⁺", but may exist in other states of ionic valency. As described above, even if the components are strictly in the state of other ion valence, the present specification deals with the case where each component is present in the glass in the ion valence of the representative value.

[ regarding the cationic component ]

Due to P⁵⁺The glass forming component is contained in an amount exceeding 0% as an essential component. Especially by containing more than 15.0% of P⁵⁺Thus, a stable glass can be formed, and the devitrification resistance of the glass can be further improved. Thus, P⁵⁺The lower limit of the content of (b) is preferably 15.0%, more preferably 20.0%, and still more preferably 23.0%.

On the other hand, by making P⁵⁺Has a content of 55.0%, and can inhibit the reaction of P⁵⁺Resulting in a decrease in refractive index and abbe number. Thus, P⁵⁺The upper limit of the content of (b) is preferably 55.0%, more preferably 48.0%, even more preferably 40.0%, still more preferably 35.0%, and particularly preferably 32.0%.

P⁵⁺Al (PO) can be used₃)₃、Ca(PO₃)₂、Ba(PO₃)₂、Zn(PO₃)₂、BPO₄、H₃PO₄And the like as a raw material.

Al³⁺Since the glass is advantageous in forming a skeleton of a fine structure of the glass and the devitrification resistance can be improved, it is necessary to contain more than 0% as an essential component. Particularly by containing 5.0% or more of Al³⁺The devitrification resistance of the glass can be further improved. Thus, Al³⁺The lower limit of the content of (b) is preferably 5.0%, more preferably 10.0%, even more preferably 13.0%, and still more preferably 16.0%.

On the other hand, by using Al³⁺Has a content of 30.0% or less, and can inhibit the generation of Al³⁺Resulting in a decrease in refractive index and abbe number. Thus, Al³⁺The upper limit of the content of (b) is preferably 30.0%, more preferably 25.0%, and still more preferably 23.0%.

Al³⁺Al (PO) can be used₃)₃、AlF₃、Al₂O₃And the like as a raw material.

Due to Ca²⁺Since the maximum value of the linear expansion coefficient of the glass can be reduced, resistance to devitrification of the glass can be improved, and a decrease in refractive index can be suppressed, the content of the glass as an essential component should be more than 0%. Thus, Ca²⁺The content of (b) is preferably more than 0%, more preferably 0.1% as a lower limit, may be more preferably more than 1.0%, further preferably more than 4.0%, further preferably more than 5.0%, further preferably more than 7.0%, further preferably more than 10.0%, further preferably more than 12.0%, further preferably more than 15.0%, particularly preferably more than 20.0%.

On the other hand, by using Ca²⁺Has a content of 35.0% or less, and can suppress excessive Ca content²⁺Resulting in a decrease in devitrification resistance and refractive index of the glass. Thus, Ca²⁺The upper limit of the content of (b) is preferably 35.0%, more preferably 30.0%, and still more preferably 28.0%. In addition, Ca²⁺The upper limit of the content of (b) may be preferably 22.0%, more preferably 18.0%, even more preferably 15.0%, and still more preferably 12.0%.

Ca²⁺Ca (PO) can be used₃)₂、CaCO₃、CaF₂And the like as a raw material.

Mg²⁺If the content exceeds 0%, the glass can be provided with an optional component for improving devitrification resistance.

On the other hand, by making Mg²⁺The content of (2) is 20.0% or less, the maximum value of the linear expansion coefficient of the glass can be reduced, and the decrease in the refractive index of the glass can be suppressed. Thus, Mg²⁺The upper limit of the content of (b) is preferably 20.0%, more preferably 15.0%, even more preferably 13.0%, and still more preferably 11.0%.

Mg²⁺MgO and MgF can be used₂And the like as a raw material.

Li⁺When the content exceeds 0%, the glass composition contains an optional component capable of lowering the glass transition temperature while maintaining high resistance to devitrification during glass formation.

On the other hand, by reacting Li⁺The content of (2) is 10.0% or less, and the maximum value of the linear expansion coefficient of the glass can be reduced. In addition, a decrease in refractive index and deterioration in chemical durability can be suppressed. Thus, Li⁺The content of (b) is more preferably 10.0% as an upper limit, more preferably less than 7.0%, still more preferably less than 4.0%, and further more preferably less than 1.0%.

Li⁺Li may be used₂CO₃、LiNO₃LiF, etc. as raw materials.

Mg²⁺Content and Li⁺The total content is preferably 20.0% or less.

In particular by reacting Mg²⁺Content and Li⁺The total content is 20.0% or less, and the maximum value of the linear expansion coefficient of the glass can be reduced, and the visible light transmittance of the glass can be improved to reduce coloring. Therefore, total amount of cation% (Mg)²⁺+Li⁺) The upper limit of (b) is preferably 20.0%, more preferably 18.0%, even more preferably 15.0%, and still more preferably 11.0%.

Sr²⁺If the content exceeds 0%, devitrification resistance of the glass can be improved and a decrease in refractive index can be suppressed. Thus, Sr²⁺The content of (b) is preferably more than 0%, and the lower limit may be set to be preferably 1.0%, more preferably 5.0%, and still more preferably 8.0%.

On the other hand, by reacting Sr²⁺Has a content of 30.0% or less, and can suppress the excessive Sr content²⁺Resulting in a decrease in devitrification resistance and refractive index of the glass. Thus, Sr²⁺The upper limit of the content of (b) is preferably 30.0%, more preferably 25.0%, and still more preferably 21.0%.

Sr²⁺Sr (NO) may be used₃)₂、SrF₂And the like as a raw material.

Ba²⁺When the content exceeds 0%, the glass can be improved in devitrification resistance, and can be improved in refractive index while maintaining low dispersibility. Thus, Ba²⁺The content of (b) is preferably more than 0%, and the lower limit may be set to be preferably 1.0%, more preferably 2.0%, and still more preferably 4.0%.

On the other hand, by making Ba²⁺The content of (B) is 30.0% or less, and excessive Ba content can be suppressed²⁺And the resulting glass has a reduced devitrification resistance. Thus, Ba²⁺The content of (b) is preferably 30.0% as an upper limit, more preferably less than 20.0%, still more preferably less than 15.0%, further preferably less than 10.0%, particularly preferably less than 9.0%.

Ba²⁺Ba (PO) can be used₃)₂、BaCO₃、Ba(NO₃)₂、BaF₂And the like as a raw material.

In the optical glass of the present invention, Sr²⁺Content and Ba²⁺The total content of Mg²⁺Content and Li⁺The ratio of the total content is preferably 10.0 or less. This can reduce the maximum value of the linear expansion coefficient of the glass, and can improve the devitrification resistance of the glass. Thus, cation ratio (Sr)²⁺+Ba²⁺)/(Mg²⁺+Li⁺) The upper limit of (b) is preferably 10.0, more preferably 8.0, more preferably 6.18, more preferably 6.0, and further preferably 4.0.

In the present invention, R²⁺Means selected from Mg²⁺、Ca²⁺、Sr²⁺And Ba²⁺At least 1 kind of (1). In the optical glass of the present invention, R is represented by²⁺OfThe content of R is 70.0% or less, and the content of R in excess can be reduced²⁺Resulting in devitrification. Thus, R²⁺The upper limit of the total content of (b) is preferably 70.0%, more preferably 65.0%, even more preferably 60.0%, and still more preferably 55.0%.

On the other hand, by containing 30.0% or more of R²⁺Thus, glass having higher devitrification resistance can be obtained. Thus, R²⁺The lower limit of the total content of (b) is preferably 30.0%, more preferably 40.0%, even more preferably 45.0%, even more preferably 48.0%, even more preferably 50.0%.

In the optical glass of the present invention, Ca²⁺Content ratio of (A) to R²⁺The ratio of the total content of (A) is preferably 0.10 or more. This makes it possible to reduce the maximum value of the linear expansion coefficient of the glass while maintaining high resistance to devitrification. Thus, cation ratio (Ca)²⁺/R²⁺) The lower limit of (b) is preferably 0.10, more preferably 0.20, still more preferably 0.30, and further preferably 0.40.

On the other hand, the upper limit of the ratio may be 1.00, but from the viewpoint of further improving resistance to devitrification, the upper limit of the ratio is preferably 0.90, more preferably 0.80, and still more preferably 0.70. The upper limit of the ratio may be preferably 0.44, more preferably 0.38, still more preferably 0.27, and still more preferably 0.24.

In the optical glass of the present invention, Ca is²⁺Has a content ratio of (2) to Sr²⁺The ratio of the content of (b) is preferably 1.00 or more. This makes it possible to reduce the maximum value of the linear expansion coefficient of the glass while maintaining high resistance to devitrification. Thus, cation ratio (Ca)²⁺/Sr²⁺) The lower limit of (b) may preferably be 1.00, more preferably 1.05, and still more preferably 1.18.

On the other hand, from the viewpoint of further improving resistance to devitrification, the upper limit of the above ratio may be preferably 3.00, more preferably 2.00, and still more preferably 1.50.

La³⁺、Gd³⁺、Y³⁺And Yb³⁺An optional component capable of improving resistance to devitrification while maintaining a high refractive index and a high Abbe number when at least one of them is contained in an amount exceeding 0%.

On the other hand, by making La³⁺、Gd³⁺、Y³⁺And Yb³⁺The content of each component is 10.0% or less, and the content of the expensive component is reduced, whereby the material cost of the glass can be reduced. In addition, devitrification caused by the excessive content of the above-mentioned components can be reduced. Thus, La³⁺、Gd³⁺、Y³⁺And Yb³⁺The content ratio of each is preferably 10.0%, more preferably 5.0%, more preferably less than 3.0%, still more preferably less than 1.0%, and still more preferably 0.5%.

La³⁺、Gd³⁺、Y³⁺And Yb³⁺La can be used₂O₃、LaF₃、Gd₂O₃、GdF₃、Y₂O₃、YF₃、Yb₂O₃And the like as a raw material.

In the present invention, Ln³⁺Means selected from Y³⁺、La³⁺、Gd³⁺And Yb³⁺At least 1 kind of (1). In the optical glass of the present invention, Ln is added³⁺Has a total content of 20.0% or less, and expensive Ln³⁺The content of (2) is reduced, and the material cost of the glass can be reduced. In addition, the content of Ln in excess can be reduced³⁺Resulting in devitrification. Thus, Ln³⁺The total content of (b) is preferably 20.0%, more preferably 10.0%, as an upper limit, more preferably less than 3.0%, still more preferably less than 1.0%, and particularly preferably less than 0.6%.

It should be noted that Ln may not be included³⁺However, in order to improve resistance to devitrification while maintaining a high refractive index and a high Abbe number, more than 0% of Ln may be contained³⁺。

Na⁺And K⁺When the content is more than 0%, the glass composition can contain an optional component capable of lowering the glass transition temperature while maintaining high devitrification resistance of the glass.

On the other hand, by reacting Na⁺And K⁺The content of (a) is 10.0% or less, and the decrease in refractive index and the deterioration in chemical durability can be suppressed. Thus, Na⁺And K⁺The upper limit of the content of (b) is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.

Na⁺And K⁺Na may be used₂CO₃、NaNO₃、NaF、Na₂SiF₆，K₂CO₃、KNO₃、KF、KHF₂，K₂SiF₆And the like as a raw material.

In the present invention, Rn⁺Means selected from Li⁺、Na⁺And K⁺At least 1 kind of (1). In the optical glass of the present invention, Rn is added⁺The total content of (A) is 20.0% or less, and the decrease in the refractive index of the glass and the deterioration in chemical durability can be suppressed. Thus, Rn⁺The upper limit of the total content of (b) is preferably 20.0%, more preferably 10.0%, and still more preferably 5.0%.

On the other hand, Rn may not be contained⁺But by containing more than 0% Rn⁺The devitrification resistance can be improved and the glass transition temperature can be lowered. Thus, Rn⁺The total content of (b) is preferably more than 0%, and the lower limit may be set to be more preferably 0.1%, and still more preferably 0.3%.

Si⁴⁺If the content exceeds 0%, the glass can be improved in devitrification resistance, increased in refractive index, and reduced in abrasion.

On the other hand, by using Si⁴⁺The content of (2) is 10.0% or less, and the content of Si in excess can be reduced⁴⁺Resulting in devitrification. Thus, Si⁴⁺The upper limit of the content of (b) is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.

Si⁴⁺SiO may be used₂、K₂SiF₆、Na₂SiF₆And the like as a raw material.

B³⁺When the content exceeds 0%, the refractive index and devitrification resistance of the glass can be improved.

On the other hand, by making B³⁺The content of (3) is 15.0% or less, and deterioration of chemical durability can be suppressed. Thus, B³⁺The upper limit of the content of (B) is preferably 15.0%, morePreferably 10.0%, more preferably 5.0%.

B³⁺Can use H₃BO₃、Na₂B₄O₇，BPO₄And the like as a raw material.

Zn²⁺If the content exceeds 0%, the glass may contain an optional component for improving devitrification resistance.

On the other hand, by reacting Zn with²⁺The content of (3) is 30.0% or less, and the decrease in refractive index can be suppressed. Thus, Zn²⁺The upper limit of the content of (b) is preferably 30.0%, more preferably 25.0%, even more preferably 10.0%, still more preferably 5.0%, and particularly preferably 3.0%.

Zn²⁺Zn (PO) can be used₃)₂、ZnO、ZnF₂And the like as a raw material.

Nb⁵⁺、Ti⁴⁺And W⁶⁺The content of the component (B) is an optional component which can increase the refractive index of the glass when the content exceeds 0%. Further, Nb⁵⁺When the content exceeds 0%, chemical durability can be improved. In addition, W⁶⁺The glass transition temperature can be lowered when the content exceeds 0%.

On the other hand, by using Nb⁵⁺、Ti⁴⁺And W⁶⁺The content of (a) is 10.0% or less, and a decrease in the Abbe number and a decrease in the visible light transmittance due to coloring of the glass can be suppressed. Thus, Nb⁵⁺、Ti⁴⁺And W⁶⁺The upper limit of the content of (b) is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.

Nb⁵⁺、Ti⁴⁺And W⁶⁺Nb can be used₂O₅、TiO₂、WO₃And the like as a raw material.

Zr⁴⁺The content of the component (B) is an optional component which can increase the refractive index of the glass when the content exceeds 0%.

On the other hand, by making Zr⁴⁺The content of (2) is 10.0% or less, and glass striae caused by volatilization of components in the glass can be suppressed. Thus, Zr⁴⁺The upper limit of the content of (B) is preferably 10.0%, more preferably 5.0%, still more preferablyPreferably 3.0%.

Zr⁴⁺ZrO may be used₂、ZrF₄And the like as a raw material.

Ta⁵⁺The content of the component (B) is an optional component which can increase the refractive index of the glass when the content exceeds 0%.

On the other hand, by using Ta⁵⁺The content of (2) is 10.0% or less, and devitrification of the glass can be reduced. Thus, Ta⁵⁺The upper limit of the content of (b) is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.

Ta⁵⁺Ta may be used₂O₅And the like as a raw material.

Ge⁴⁺If the content exceeds 0%, the refractive index of the glass can be increased and devitrification resistance can be improved.

On the other hand, by using Ge⁴⁺Has a content of 10.0% or less, and expensive Ge⁴⁺The content of (2) is reduced, so that the material cost of the glass can be reduced. Thus, Ge⁴⁺The content of (b) is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.

Ge⁴⁺GeO may be used₂And the like as a raw material.

Bi³⁺And Te⁴⁺When the content exceeds 0%, the refractive index of the glass can be increased and the glass transition temperature can be lowered.

On the other hand, by using Bi³⁺Has a content of 10.0% or less, and/or Te⁴⁺The content of (2) is 15.0% or less, and devitrification of the glass and a decrease in visible light transmittance due to coloring can be suppressed. Thus, Bi³⁺The upper limit of the content of (b) is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%. In addition, Te⁴⁺The upper limit of the content of (b) is preferably 15.0%, more preferably 10.0%, and still more preferably 5.0%.

Bi³⁺And Te⁴⁺Bi can be used₂O₃、TeO₂And the like as a raw material.

[ regarding the anionic component ]

The optical glass of the present invention contains F^-. In particular toOver 30.0% of F^-The Abbe number of the glass can be increased and the devitrification resistance of the glass can be improved. Thus, F^-The content of (b) is preferably 30.0%, more preferably 40.0%, even more preferably 50.0%, still more preferably 55.0%, and particularly preferably 60.0%.

On the other hand, by making F^-The content of (3) is 80.0% or less, and the decrease in the degree of abrasion of the glass can be suppressed. Thus, F^-The upper limit of the content of (b) is preferably 80.0%, more preferably 75.0%, even more preferably 70.0%, and still more preferably 67.0%.

F^-AlF may be used₃、MgF₂、BaF₂And fluoride of various cationic components as a raw material.

The optical glass of the present invention contains O^2-. Especially by containing 20.0% or more of O^2-Devitrification of the glass and increase in abrasion degree can be suppressed. Thus, O^2-The content of (b) is preferably 20.0%, more preferably 25.0%, even more preferably 30.0%, and still more preferably 33.0%.

On the other hand, by reacting O^2-The content of (3) is 70.0% or less, the maximum value of the linear expansion coefficient of the glass can be suppressed to a low value, and the effect by other anion components can be easily obtained. Thus, O^2-The upper limit of the content of (b) is preferably 70.0%, more preferably 60.0%, even more preferably 50.0%, still more preferably 45.0%, and particularly preferably 40.0%.

Further, from the viewpoint of suppressing devitrification of the glass, O is^2-Content ratio of (A) and F^-The total content of (b) is preferably 98.0%, more preferably 99.0%, and still more preferably 100%.

O^2-Al may be used₂O₃Oxides of various cationic components such as MgO and BaO, or Al (PO)₃、Mg(PO)₂，Ba(PO)₂And phosphates of various cationic components.

[ with respect to other components ]

If necessary, other components may be added to the optical glass of the present invention within a range not to deteriorate the characteristics of the glass of the present invention.

[ regarding components that should not be contained ]

Next, components that should not be contained in the optical glass of the present invention and components that are not preferably contained therein will be described.

In addition to Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, cations of transition metals such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo have properties of coloring the glass and generating absorption at a specific wavelength in the visible region even when they are contained in a small amount alone or in combination, and therefore, it is preferable that they are not substantially contained in optical glass using a wavelength in the visible region.

In recent years, the use of cations of Pb, As, Th, Cd, Tl, Os, Be, and Se As harmful chemical substances tends to Be controlled, and measures for environmental protection are required not only in the glass production process but also in the processing process and the treatment after commercialization. Therefore, when importance is attached to the influence on the environment, it is preferable that the components are not substantially contained except for inevitable mixing. Thus, the optical glass does not substantially contain substances contaminating the environment. Therefore, the optical glass can be manufactured, processed and discarded without taking special measures in terms of environmental protection.

Cations of Sb and Ce are useful as a defoaming agent, but in recent years, the cations tend not to be contained in optical glass as an environmentally unfriendly component. Therefore, from the above-described aspect, the optical glass of the present invention preferably does not contain Sb or Ce.

[ production method ]

The method for producing the optical glass of the present invention is not particularly limited. For example, the above raw materials are mixed uniformly so that the respective components are within a predetermined content range, the prepared mixture is put into a quartz crucible, an alumina crucible, or a platinum crucible, and after a rough melting, the mixture is put into a platinum crucible, a platinum alloy crucible, or an iridium crucible, and a melting is performed at a temperature of 900 to 1200 ℃ for 2 to 10 hours, and after stirring to homogenize and defoam the mixture, the temperature is lowered to 850 ℃ or lower, and after a finish stirring, the cord is removed, and the mixture is cast into a mold and slowly cooled, whereby an optical glass can be produced.

[ Properties ]

For the optical glass of the present invention, the maximum value (α) of the linear expansion coefficient in the temperature range between the glass transition temperature (Tg) and the yield point (At)_max) Preferably 1500X 10^-7K^-1The following. Thus, even if the glass is heated to a temperature higher than the glass transition temperature and press-molded, the glass is less likely to be broken, and therefore, the productivity of the optical element can be improved. The reason why the glass is hard to break as described above includes, for example: when glass is heated and softened or when the softened glass is press-molded and cooled, the glass is divided into a high-temperature portion having a high linear expansion coefficient and a low-temperature portion having a low linear expansion coefficient and a glass transition temperature, due to a temperature difference in the glass, and the high-temperature portion is thermally expanded and thermally contracted, and thus a force applied to the low-temperature portion by thermal expansion and thermal contraction of the high-temperature portion is reduced.

Therefore, in the optical glass of the present invention, the maximum value (α) of the linear expansion coefficient in the temperature range between the glass transition temperature (Tg) and the yield point (At)_max) Preferably, the upper limit of (2) is 1500X 10^-7K^-1More preferably 1450X 10^-7K^-1More preferably 1400X 10^-7K^-1On the other hand, the maximum value of the above linear expansion coefficient (α)_max) The lower limit of (B) may preferably be 500X 10^-7K^-1More preferably 600X 10^-7K^-1More preferably 700X 10^-7K^-1。

In the present specification, the maximum value of the linear expansion coefficient in the temperature range between the glass transition temperature (Tg) and the yield point (At) may be abbreviated as "maximum value of the linear expansion coefficient".

For the optical glass of the present invention, the optical glass is obtained by maximizing the linear expansion coefficient (α) in the temperature range between the glass transition temperature (Tg) and the yield point (At)_max) The optical constants are not limited in nature because the desired problems can be solved as specified below. However, this findingThe maximum value of the linear expansion coefficient is below the specified value and the content P⁵⁺And F^-The fluorophosphate glass of (1) preferably has a predetermined refractive index and a low dispersibility (high Abbe number).

In particular, the lower limit of the refractive index (nd) of the optical glass of the present invention is preferably 1.40, more preferably 1.43, and still more preferably 1.45. The upper limit of the refractive index may be preferably 2.00, more preferably 1.80, and still more preferably 1.60. By having the above refractive index, a large amount of light refraction can be obtained even if the optical element is thinned.

The lower limit of the abbe number (vd) of the optical glass of the present invention is preferably 60, more preferably 63, and still more preferably 66. The upper limit of the abbe number may be preferably 90, more preferably 88, and still more preferably 85. By having the above-described low dispersion, even with a single lens, it is possible to reduce a focus deviation (chromatic aberration) caused by the wavelength of light.

The refractive index (nd) and Abbe number (vd) are values measured according to Japan optical Nitri Industrial Standard J0GIS 01-2003.

The optical glass of the present invention preferably has high devitrification resistance (in the specification, it may be simply referred to as "devitrification resistance") when the glass is produced. Accordingly, since a decrease in transmittance due to crystallization of glass or the like in glass production can be suppressed, the above optical glass can be preferably used for an optical element that transmits visible light, such as a lens. As a measure showing high devitrification resistance in the production of glass, for example, a low liquidus temperature is mentioned.

The optical glass of the present invention preferably has a glass transition temperature of 550 ℃ or lower. Thus, since the glass softens at a lower temperature, the glass can be press-molded at a lower temperature. Further, oxidation of the mold used for press molding can be reduced, and the life of the mold can be prolonged. Therefore, the upper limit of the glass transition temperature of the optical glass of the present invention is preferably 550 ℃, more preferably 520 ℃, and still more preferably 500 ℃. The lower limit of the glass transition temperature of the optical glass of the present invention is not particularly limited, but the lower limit of the glass transition temperature of the optical glass of the present invention may be preferably 100 ℃, more preferably 200 ℃, and still more preferably 300 ℃.

In addition, the optical glass of the present invention preferably has a yield point (At) of 650 ℃ or lower. The yield point is one of indexes indicating the softening property of glass similarly to the glass transition temperature, and is an index indicating a temperature close to the press molding temperature. Therefore, by using glass having a yield point of 650 ℃ or less, press molding can be performed at a lower temperature, and therefore press molding can be performed more easily. Therefore, the upper limit of the yield point of the optical glass of the present invention is preferably 650 ℃, more preferably 620 ℃, and most preferably 600 ℃. The lower limit of the yield point of the optical glass of the present invention may preferably be 150 ℃, more preferably 250 ℃, and still more preferably 350 ℃.

[ preform and optical element ]

For example, a glass molded body can be produced from the optical glass obtained by a mold press molding method such as reheating press molding or precision press molding. That is, a preform for press molding may be produced by using an optical glass production mold, and the preform may be heated and press molded and then polished to produce a glass molded body; alternatively, a glass molded body is produced by precision press molding of a preform produced by polishing or a preform molded by known float molding or the like. The method for producing the glass molded product is not limited to these methods.

The glass molded body produced as described above is useful for various optical elements and optical designs. In particular, it is preferable to produce an optical element such as a lens, a prism or a mirror from the optical glass of the present invention by a method such as precision press molding. Thus, when an optical device such as a camera or a projector that transmits visible light through an optical element is used, high-definition and high-precision imaging characteristics and the like can be realized, and the optical system in the optical device can be miniaturized.

Examples

The glass compositions (expressed in terms of cation% or mole% in terms of anion%), the refractive indices (nd), and the refractive indices (nd) of the optical glasses of the present invention according to examples (Nos. 1 to 12) and comparative example (No. A),Abbe number (vd), glass transition temperature (Tg), yield point (At), and maximum value of linear expansion coefficient (α)_max) Tables 1 to 2 show the results. It should be noted that the following examples are for illustrative purposes only and are not limited to these examples.

The optical glasses of the examples and comparative examples of the present invention were produced as follows: high-purity raw materials used in general fluorophosphate glasses such as oxides, carbonates, nitrates, fluorides, metaphosphoric acid compounds, etc. corresponding to the raw materials of each component were selected, weighed to the composition ratios of the respective examples shown in the table, mixed uniformly, put into a platinum crucible, melted in an electric furnace at a temperature ranging from 900 to 1200 ℃ for 2 to 10 hours according to the ease of melting of the glass composition, homogenized by stirring, defoamed, etc., then cooled to 850 ℃ or lower, cast into a mold, and slowly cooled to produce glass.

Here, the refractive index and abbe number of the glasses of examples and comparative examples were measured based on japanese optical nitre industrial society standard J0GIS 01-2003. The glass used for the measurement was treated in a slow cooling furnace under annealing conditions at a slow cooling rate of-25 ℃/hr.

The glass transition temperature (Tg) and the yield point (At) of the glasses of examples and comparative examples were determined as follows: the thermal expansion curve was obtained from the relationship between the measurement temperature and the elongation of the sample according to "method for measuring thermal expansion of optical glass" of Japan optical glass Industrial Association Standard J0GIS 08-2003.

Further, the maximum value of the linear expansion coefficient of the glasses of examples and comparative examples (α)_max) The following is obtained: the measurement was carried out in accordance with Japanese society for optical and Nitro Standard J0GIS08-2003, "method for measuring thermal expansion of optical glass", and the maximum value of the linear expansion coefficient per 5 ℃ from the glass transition temperature (Tg) to the yield point (At) was determined. The linear expansion coefficient was calculated using the sample length at a temperature which is a multiple of 5.

[ Table 1]

[ Table 2]

As shown in the table, for the optical glasses of examples of the present invention, the maximum value of the linear expansion coefficient (α) in the temperature range between the glass transition temperature (Tg) and the yield point (At)_max) All of them having an upper limit of 1500X 10^-7K^-1Hereinafter, the more detailed description is 900 × 10^-7K^-1Hereinafter, the maximum value of the linear expansion coefficient (α) of the glass of comparative example (No. A)_max) Is higher than 1500 × 10^-7K^-1Therefore, it is found that the maximum value of the linear expansion coefficient (α) of the optical glass of the example of the present invention is higher than that of the glass of the comparative example_max) The upper limit of (3) is small.

The optical glasses according to the examples of the present invention have refractive indices of 1.40 or more, more specifically 1.49 or more, and 2.00 or less, more specifically 1.55 or less, within desired ranges.

The optical glasses according to examples of the present invention all have an abbe number of 60 or more, more specifically 79 or more, and an abbe number of 90 or less, more specifically 83 or less, within a desired range.

The glass transition temperatures of the optical glasses of the examples of the present invention are all 550 ℃ or lower, more specifically 470 ℃ or lower, within desired ranges.

The yield points of the optical glasses according to the examples of the present invention are all 650 ℃ or lower, more specifically 510 ℃ or lower, and fall within a desired range.

Accordingly, it is found that the optical glass of the example of the present invention has an abbe number within a desired range, a desired refractive index, and a maximum value of linear expansion coefficient (α)_max) The upper limit of (3) is small.

Further, the optical glass of the example of the present invention was press-molded and processed into a lens or prism shape. As a result, it was found that when the optical glass of example (No.7) having a small maximum value of the linear expansion coefficient was press-molded, breakage occurred most hardly in the glass after molding. Therefore, the optical glass of the example of the present invention is less likely to crack after press molding because the maximum value of the linear expansion coefficient is smaller than that of the glass of the comparative example.

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

Claims

1. An optical glass having a maximum value (α) of a linear expansion coefficient in a temperature range between a glass transition temperature (Tg) and a yield point (At)_max) Is 1500 multiplied by 10^-7K^-1The following.

2. The optical glass according to claim 1, wherein P is contained⁵⁺、Al³⁺And Ca²⁺As a cationic component, O is contained^2-And F^-As the anionic component.

3. The optical glass according to claim 1, wherein P is contained in an amount of 15.0 to 55.0% in terms of cation% (mol%)⁵⁺5.0 to 30.0% of Al³⁺And 0.1 to 35.0% of Ca²⁺。

4. The optical glass according to claim 1, wherein the glass composition, expressed in terms of cation% (mol%),

Mg²⁺the content of (B) is0 to 20.0%,

Li⁺the content of (B) is0 to 10.0%.

5. The optical glass of claim 1, wherein Mg²⁺Content and Li⁺The total content (cation%) is 20.0% or less.

6. The optical glass according to claim 1, wherein the glass, expressed as anion% (mol%),

F^-the content of (B) is 30.0 to 80.0%,

O^2-the content of (B) is 20.0 to 70.0%.

7. The optical glass according to claim 1, wherein the glass composition, expressed in terms of cation% (mol%),

Sr²⁺the content of (B) is0 to 30.0%,

Ba²⁺the content of (B) is0 to 30.0%.

8. The optical glass as defined in claim 1, wherein Sr²⁺Content and Ba²⁺The total content of Mg²⁺Content and Li⁺The total ratio of the contents of (Sr)²⁺+Ba²⁺)/(Mg²⁺+Li⁺) Is 10.0 or less.

9. The optical glass of claim 1, wherein R²⁺The total content (cation%) of (C) is 30.0 to 70.0%, R²⁺Is selected from Mg²⁺、Ca²⁺、Sr²⁺And Ba²⁺At least 1 kind of (1).

10. The optical glass as claimed in claim 1, wherein Ca²⁺Content ratio of (A) to R²⁺Ca as the ratio of the total content (cation%) (ii)²⁺/R²⁺Is 0.10 or more, R²⁺Is selected from Mg²⁺、Ca²⁺、Sr²⁺And Ba²⁺At least 1 kind of (1).

11. The optical glass according to claim 1, wherein the glass is a glass having a refractive index expressed in terms of cationic% (mol%),

La³⁺the content of (B) is0 to 10.0%,

Gd³⁺the content of (B) is0 to 10.0%,

Y³⁺has a content of 0 to 10.0％，

Yb³⁺The content of (B) is0 to 10.0%.

12. The optical glass of claim 1, wherein Ln³⁺The total content (cation%) of (C) is 0-20.0%, Ln³⁺Is selected from La³⁺、Gd³⁺、Y³⁺And Yb³⁺At least 1 kind of (1).

13. The optical glass according to claim 1, wherein the glass composition, expressed in terms of cation% (mol%),

Na⁺the content of (B) is0 to 10.0%,

K⁺the content of (B) is0 to 10.0%.

14. The optical glass of claim 1, wherein Rn⁺Has a total content of (cation%) of 20.0% or less, Rn⁺Is selected from Li⁺、Na⁺And K⁺At least 1 kind of (1).

15. The optical glass according to claim 1, wherein the glass composition, expressed in terms of cation% (mol%),

Si⁴⁺the content of (B) is0 to 10.0%,

B³⁺the content of (B) is0 to 15.0%,

Zn²⁺the content of (B) is0 to 30.0%,

Ti⁴⁺the content of (B) is0 to 10.0%,

Nb⁵⁺the content of (B) is0 to 10.0%,

W⁶⁺the content of (B) is0 to 10.0%,

Zr⁴⁺the content of (B) is0 to 10.0%,

Ta⁵⁺the content of (B) is0 to 10.0%,

Ge⁴⁺the content of (B) is0 to 10.0%,

Bi³⁺the content of (B) is0 to 10.0%,

Te⁴⁺the content of (B) is0 to 15.0%.

16. An optical element formed of the optical glass of any one of claims 1 to 15.

17. A preform for use in polishing and/or precision press molding, which is formed from the optical glass according to any one of claims 1 to 15.

18. An optical element formed by precision pressing the preform according to claim 17.