JPH1129338A - Optical glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain glass excellent in chemical resistance by bringing the glass to contain a specific weight % of SiO2 , B2 O3 , ZnO, R<2> , R<1> 2 O, Sb2 O3 and one or more compounds selected from Al, Ti, Y, Zr, Nb, La, Gd, Yb, Ta, and W, and giving the glass a specific refractive index and an Abbe's number. SOLUTION: The optical glass having 1.60-1.70 refractive index and 40-55 Abbe's number is obtained by preparing glass raw material in a predetermined ratio, heat and melt at 1200-1400 deg.C, bring to homogeneous by agitation after clearing, pore into a mold and cool slowly. The glass comprises 10-50 wt.% of SiO3 , 4-30 wt.% of B2 O3 , 20-60 wt.% of ZnO, 3-40 wt.% of R2 O, 0-1 wt.% of Sb2 O3 and 0-5 wt.% of one or more of compounds selected from metal compounds of Al, Tm, Y, Zr, Nb, La, Gd, Yb, Ta and W. In the composition, R<2> O is (MgO+CaO+SrO+BaO) and R'2 O is (Li2 O+Na2 O+K2 O).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical glass having a medium refractive index and a medium dispersion, and having excellent chemical durability and stability against devitrification.

[0002]

2. Description of the Related Art The refractive index (nd) is from 1.60 to 1.70.
As glass having an optical constant such that the Abbe number (νd) is 40 to 55, SiO ₂ —B ₂ O ₃ —Zn
Extra heavy crown glass (SSK), barium flint glass (Ba) having a composition of O-BaO-PbO
F), heavy barium flint glass (BaSF) and the like are known (Literature: Glass Composition Data Book, published by Japan Glass Products Association, 1991, p.92, 97, 9).
8, 99). For example, as one of the SSKs, for example, the composition of SSK1 is 3% by weight of SiO _2.
8.5, B ₂ O ₃ is 6.3, ZnO is 8.0, BaO is 39.7, PbO is 4.0, Al ₂ O ₃ is 2.5, As
₂ O ₃ is 1.0, the refractive index (nd) of the optical glass is 1.6172, and the Abbe number (νd) is 53.
Nine.

[0003]

The above SSK, BA
In conventional optical glasses such as F and BASF, lead oxide (PbO) is a material that increases the refractive index of the glass,
In addition, it has a high glass forming ability, and further has a yield temperature (hereinafter referred to as At
In some cases. ) Was often used as a material for lowering). Arsenic oxide (As ₂ O ₃ ) has been used as a defoaming agent.

[0004] However, since these glasses contain lead and arsenic, it is necessary to take various measures against lead and arsenic in consideration of the working environment and the collection and disposal of waste in the manufacturing process of the glass. Was.

For this reason, there has been a demand for an optical glass which does not contain lead or arsenic and has an optical constant having a refractive index of 1.60 to 1.70 and an Abbe number of 40 to 55.

[0006]

SUMMARY OF THE INVENTION For this reason, the present inventor has made an acute
As a result of repeated research, SiO silicate_Two , Boric acid B_Two O
_Three , Zinc oxide ZnO and alkaline earth metal oxide R^Two 
Depending on the optical glass composition containing O as an essential component,
It has a scientific constant, and has stability and chemistry against devitrification.
That optical glass with excellent mechanical durability can be obtained
Thus, the present invention has been made.

[0007] The optical glass of this invention, the following composition in weight percent _{(wt%), SiO 2 10~50} B 2 O 3 4~30 ZnO 20~60 R 2 O 3~40 R 1 2 O 0~10 Sb ₂ O ₃ 0-1 Al, Ti, Y, Zr, Nb, La, Gd, Yb, T
a, one or two or more compounds selected from the group of compounds of the metals a and W, each having 0 to 5 and a refractive index (nd) of 1.60 to 1.7.
It is characterized by having an optical constant of 0 and an Abbe number (νd) of 40 to 55.

However, the total composition range of SiO ₂ and B ₂ O ₃ is 25 to 60 wt%. R ² O is M
It is composed of at least one selected from the group consisting of gO, CaO, SrO and BaO, or a combination of two or more thereof.
aO is 0-20 wt%, SrO is 0-20 wt%, Ba
O is contained within a composition range of 0 to 40 wt%.

Further, R ¹ ₂ O is at least one selected from the group consisting of Li ₂ O, Na ₂ O and K ₂ O, or consists of a combination of two or more of of these.

Also, Al, Ti, Y, Zr, Nb, L
a, Gd, Yb, Ta, and W compounds, for example, one or two compounds selected from the group including oxides and fluorides such as Al ₂ O ₃ , TiO ₂ , and Nb ₂ O ₅ , and other compounds The above compounds are selected and contained. Here, for example, if Al ₂ O ₃ and TiO ₂ are selected as two kinds of compounds,
These oxides (Al ₂ O ₃ , TiO ₂ )
It can be contained within the range of ５5 wt%.

The above composition ranges have been found experimentally, and the reasons for limiting the range of each component are as follows.

First, SiO ₂ silicate is a glass-forming oxide, and is an essential component for lowering the refractive index of glass and improving the chemical durability. To maintain stability against devitrification, It is preferred that the content be 10 wt% or more. Further, the melting temperature and the yielding temperature (At) of the glass
Is preferably not more than 50% by weight in order not to increase the amount.

When the yield temperature (At) is high, when an optical glass product is manufactured later, for example, in a pressing process,
There is a possibility that the material of the press die or the release material is restricted, or the working efficiency is deteriorated. For this reason, it is preferable to suppress an increase in the yielding temperature (At) and to set At to preferably about 600 ° C.

Boric acid B ₂ O ₃ , like SiO ₂ , is a glass-forming oxide and is a component that lowers the melting temperature and yield temperature (At) of glass. 4wt% to maintain stability and chemical durability against devitrification of glass
% Or more and 30 wt% or less.

[0015] In order to maintain the stability and chemical durability against devitrification, and the total amount of content in order not to increase the melting temperature and the content of _{SiO 2 B 2 O 3 (SiO} 2 + B ₂ O ₃ ) 25 wt% or more, 60 wt%
It is better to:

Zinc oxide ZnO is 20 wt% or more, 60 w
It is contained in a relatively large amount so as to be at most t%. It is made of TiO ₂ or Nb ₂ O added as a modifying component of glass.
_This is for minimizing the content of a component for coloring glass such as ₅ and for not containing highly toxic PbO here. ZnO is a component that lowers the melting temperature and the yield temperature (At) of the glass and improves the chemical durability. To obtain these effects, it is preferable that ZnO be contained in an amount of 20 wt% or more. Further, the content of SiO ₂ and B ₂ O ₃ in the glass was 25 wt.
% To 60 wt% or less, the ZnO content is preferably set to 60 wt% or less.

The alkaline earth metal oxide R ² O (M
(gO + CaO + SrO + BaO) is a component that generally enhances the glass-forming ability and improves the meltability and stability against devitrification. In order to improve the melting property of the glass, it is preferable to contain 3 wt% or more. In order to provide the stability against devitrification by the glass forming oxides SiO ₂ and B ₂ O ₃ , the glass forming oxide should be used. When the content of certain SiO ₂ and B ₂ O ₃ is 25 wt% or more,
It is necessary to secure 60 wt% or less. Therefore, R ² O
Is preferably not more than 40 wt%.

Further, as the alkaline earth metal oxide,
One of MgO, CaO, SrO, and BaO may be selected and contained, or two or more of these may be selected and contained. In addition, MgO + CaO + SrO
+ BaO means that R ² O is composed of components MgO, CaO, SrO,
And BaO. Further, it is preferable that the content of each of MgO, CaO and SrO be within 20 wt%. B
It is preferable that the content of aO be within 40 wt%.

By adding an appropriate amount of another substance as an optional component in addition to the above essential components, the optical constant of the glass can be made closer to a desired value, and the melting temperature is lowered to facilitate melting. Therefore, the adverse effect on the glass due to the erosion of the crucible can be reduced.

[0020] As optional component added to the alkali metal oxides ^{_{R 1 2 O (Li 2 O}} + Na 2 O + K 2
O) is a component capable of lowering the melting temperature and the yielding temperature (At). However, in order to suppress the elution of platinum in the crucible and maintain the chemical durability, the content is preferably 10% by weight or less. Li ₂ is used as an alkali metal oxide.
One of O, Na ₂ O and K ₂ O may be selected and contained, or two or more of these may be selected and contained. _{Incidentally, Li 2 O + Na 2 O} + K 2 O is, R ¹ ₂
This means that O is represented by the total content of the components Li ₂ O, Na ₂ O and K ₂ O.

Although antimony (III) oxide Sb ₂ O ₃ is used as a defoaming agent, a sufficient defoaming effect can be obtained.
In order not to lower the internal transmittance of the glass, it is necessary to:
The content is preferably 0% by weight or less.

In the optical glass of the present invention, in addition to the above components, Al, Ti, Y, Zr, Nb, L
One, two or more compounds selected from the compound group of each metal of a, Gd, Yb, Ta, and W can be contained.

These compounds adjust the optical performance to be applied to glass of various optical systems, further enhance the chemical durability, improve the stability of the glass, and adjust the viscosity of the melt. Or a small amount to contain it. However, in a glass containing a large amount of TiO ₂ , Nb ₂ O ₅ and WO ₃ , the transmittance of a wavelength on the short wavelength side in the visible region tends to decrease. desirable. For this reason, it is preferable that the above oxide be contained in a range of 5 wt% or less.

Preferred compositions of the optical glass of the present invention include, for example, the following composition examples.

By weight%, SiO ₂ is 17.2, B ₂ O ₃
Is 19.0, ZnO is 56.5, SrO is 3.9, R ¹ ₂
O is not contained, Sb ₂ O ₃ is 0.2, ZrO ₂
3.9. The refractive index (nd) is 1.672, the Abbe number (νd) is 47.4, and the yield temperature (A
t) is 610 ° C.

The optical glass having such a composition has the above-mentioned desired optical constant range (refractive index (nd) 1.60 to 1.60).
70, Abbe number (νd) 40 to 55), and is excellent in stability against devitrification and chemical durability. The yield temperature (At) is also suppressed to 610 ° C.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below with reference to working composition examples. It should be noted that the materials used and the amounts thereof, other numerical conditions, and treatment methods mentioned in the following description are merely examples within the scope of the preferred invention, and therefore, the invention is not limited thereto. .

The optical glass of this example was manufactured by the following method.

First, corresponding oxides, carbonates, nitrates, fluorides, these compounds and the like are used as raw materials of the respective components, and they are weighed at desired ratios, respectively.
This was mixed well in a powder or a solution to obtain a prepared raw material. Next, this was put into a platinum or quartz crucible in an electric furnace heated from 1200 ° C. to 1400 ° C., melted, clarified, and then stirred to homogenize. Thereafter, it was cast into a pre-heated iron mold and gradually cooled.

The compositions (expressed in weight percent (wt%)), optical constants (refractive index (nd), Abbe number (νd)), and yield temperature (A) of the examples of the optical glass of the present invention.
t) is shown in Table 1.

The compositions of the examples are expressed as weight percentages of oxides when cations contained in the glass are calculated as oxides. In addition, those in which the contents and components are changed within the limited range are indicated by five types of compositions.

[0032]

[Table 1]

According to Table 1, the composition of Composition Example 1 is expressed in terms of% by weight.
Where 45.7 for SiO ₂ , 5.2 for B ₂ O ₃ , 33.3 for ZnO, 7.3 for CaO, 1.6 for Na ₂ O, and K ₂ O
Is 2.5, Sb ₂ O ₃ is 1.0, TiO ₂ is 2.9, A
l ₂ O ₃ is 0.7. R ² O in this example is CaO7.
It is 3, R ¹ ₂ O is Na ₂ O1.6 and K ₂ O2.5
Is 4.1.

The composition of composition example 2 is% by weight, and SiO ₂ is 2% by weight.
2.9, 4.2 for B ₂ O ₃ , 32.4 for ZnO, CaO
6.0, BaO 27.5, Na ₂ O 1.2, K ₂
O is 2.1, Sb ₂ O ₃ is 0.8, TiO ₂ is 2.4,
Al ₂ O ₃ is 0.5. R ² O in this example is CaO
6.0 and BaO27.5 with a 33.5, R ¹ ₂ O
Is 3.3 in Na ₂ O1.2 and K ₂ O2.1.

The composition of Composition Example 3 is by weight, and SiO ₂ is 1%.
7.2, B ₂ O ₃ is 19.0, ZnO is 56.5, Sr
O is 3.9, Sb ₂ O ₃ is 0.2, and ZrO ₂ is 3.9. R ² O in this example is SrO3.9, R ¹ ₂ O is not contained.

The composition of Composition Example 4 is% by weight, and SiO ₂ is 1%.
7.3, B ₂ O ₃ 24.4, ZnO 24.4, Mg
O is 19.1, CaO is 9.9, and SrO is 5.0. R ² O is MgO19.1 in this example, a 34.0 by CaO9.9 and SrO5.0, R ¹ ₂ O is not contained.

The composition of Composition Example 5 is% by weight, and SiO ₂ is 2% by weight.
6.8, B ₂ O ₃ is 9.4, ZnO is 20.2, BaO
Is 36.5, Li ₂ O is 1.1, Sb ₂ O ₃ is 1.0,
TiO ₂ is 3.0 and Al ₂ O ₃ is 2.0. R ² O in this example is BaO36.5, R ¹ ₂ O is Li ₂ O
1.1.

The composition of the conventional optical glass and the extra-heavy crown glass SSK1 of the above-mentioned literature is expressed in terms of% by weight.
iO ₂ is 38.5, B ₂ O ₃ is 6.3, ZnO is 8.
0, BaO is 39.7, Al ₂ O ₃ is 2.5, PbO is 4.0, As ₂ O ₃ is 1.0. R ² O in this example is BaO39.7, R ¹ ₂ O is not contained.

As a conventional optical glass, the composition of barium flint glass BAF10 is% by weight, and SiO ₂ is 30% by weight.
9, B ₂ O ₃ is 9.2, ZnO is 5.3, CaO is 4.
0, BaO is 41.3, TiO ₂ is 3.6, Al ₂ O ₃
Is 0.3, PbO is 4.6, As ₂ O ₃ is 0.3. R ² O in this example is CaO 4.0 and BaO 41.
It is 3, R ¹ ₂ O is not contained.

As a conventional optical glass, the composition of heavy barium flint glass BASF6 is% by weight, and SiO ₂ is 3% by weight.
4.9, B ₂ O ₃ is 4.5, ZnO is 4.6, CaO is 5.6, BaO is 25.8, Sb ₂ O ₃ is 0.3, Na
₂ O is 1.1, K ₂ O is 1.9, TiO ₂ is 2.5, P
bO is 18.0, As ₂ O ₃ is 0.3, and Al ₂ O ₃ is 0.5. R ² O in this example is CaO 5.6 and B
aO25.8 with a 31.4, R ¹ ₂ O is Na ₂ O1.
1 and K ₂ O1.9 3.0.

The glass of any of Composition Examples 1 to 5
The refractive index (nd) is in the range of 1.60 to 1.70, and the Abbe number (νd) is in the range of 40 to 55.

The yield temperature of the glasses of Composition Examples 1 to 5 is in the temperature range of 610 ° C. to 640 ° C. Therefore, it can be said that these glasses are excellent in workability.

Further, the solubility of the glass of each composition example in water was examined by observing the polished surface state of the glass. As a result, it was evaluated that all of the glasses of Composition Examples 1 to 5 can be sufficiently used as products. It can be said that this is excellent in chemical durability. As for the stability against devitrification, the state of devitrification was observed by bringing the glass material of each composition example into a molten state and then lowering the temperature at a constant rate. Here, 100 per hour
When the temperature was decreased by ° C., it was confirmed that the glasses of Composition Examples 1 to 5 did not devitrify, and thus were excellent in stability against devitrification.

Thus, in the optical glass of the present invention, the refractive index (nd) is in the range of 1.60 to 1.70, and the Abbe number (νd) is in the range of 40 to 55. It is also excellent in chemical durability, stability against devitrification, and workability.

[0045]

According to the optical glass of the present invention described above, the refractive index (nd) satisfies the range of 1.60 to 1.70 and the Abbe number (νd) of 40 to 55, which is an optical constant. In addition, it is possible to obtain an optical glass which does not contain lead and arsenic which are harmful to a living body and which has excellent chemical durability and stability against devitrification. Further, the yielding temperature of the obtained glass can be suppressed to such an extent that the working efficiency is not reduced. For this reason, it is possible to obtain high-quality glass having high optical efficiency, which is a glass having the above optical constants.

Claims (1)

[Claims] 1. The following composition in weight percent: SiO ₂ 10-50 B ₂ O ₃ 4-30 (where SiO ₂ + B ₂ O ₃ 25-60) ZnO 20-60 R ² O 3-40 (where R ² O is MgO, CaO, SrO and Ba
At least one selected from the group of O, or a combination of two or more thereof;
0-20, CaO 0-20, SrO 0-20, B
aO is _{^{0~40,) R 1 2 O 0~10}} ( provided that, R ¹ ₂ O is at least one selected from the group consisting of Li ₂ O, Na ₂ O and K ₂ O, or in these Sb ₂ O ₃ 0-1 Al, Ti, Y, Zr, Nb, La, Gd, Yb, T
a, one or two or more compounds selected from the group of compounds of the metals a and W, each having 0 to 5 and a refractive index (nd) of 1.60 to 1.7.
An optical glass having an optical constant of 0 and an Abbe number (νd) of 40 to 55.