JP2001342035A - Optical glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical glass which has a high refractive index, high dispersibility and light weight, and suppresses deterioration of the coloring without using an arsenic compound or a fluorine compound. SOLUTION: The contents of SiO2, Na2O, BaO, TiO2 and Nb2O5 in the optical glass are 22.0-35.0 wt.%, 4.0-17.0 wt.%, 2.0-25.0 wt.%, 18.0-27.0 wt.% and 13.0-26.0 wt.%, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical glass used for an optical apparatus, and more particularly to an optical glass having a high refractive index, a high dispersion, a light weight, and a suppressed deterioration in coloring.

[0002]

2. Description of the Related Art A conventional optical glass having a high refractive index, a high dispersion and a light weight contains a large amount of TiO _2, Nb ₂ O _{5, and the} like, and is easily colored during melting. In order to prevent this coloring, an arsenic compound (such as As ₂ O ₃ ) and a fluorine compound (such as a fluoride of an alkali metal or an alkaline earth metal) have been added to the optical glass.

[0003]

However, since arsenic compounds and fluorine compounds are substances that are likely to have an adverse effect on the environment and the human body, it has been desired to not use them as optical glass components. The present invention has been made in view of such a conventional problem, and provides an optical glass which has a high refractive index, a high dispersion, a light weight, a reduced degree of coloring, and does not contain an arsenic compound or a fluorine compound. It is intended to do so.

[0004]

According to the present invention, the weight%
And SiO ₂ : 22.0 to 35.0%, Na ₂ O: 4.0
~ 17.0%, BaO: 2.0 ~ 25.0%, Ti
O ₂ : 18.0 to 27.0%, Nb ₂ O ₅ : 13.0 to ₂
An optical glass is provided, which contains 6.0% of each component.

At this time, from the viewpoint of adjusting the optical constant according to the use of the lens, the optical glass is expressed as
₂ O: 8.0% or less (however, the total amount of Na ₂ O and K ₂ O is 8.0 to 17.0%), SrO: 10.0% or less, B
₂ O ₃ : 1.0% or less, Al ₂ O ₃ : 2.0% or less, Mg
O: 3.0% or less, ZnO: 3.0% or less, Y ₂ O ₃ :
3.0% or less, Ta ₂ O ₅ : 3.0% or less, Li ₂ O:
One or two or more components of 3.0% or less and ZrO ₂ : 4.0% or less may be contained.

[0006] At least one of Sb ₂ O ₃ , SnO and SnO ₂ is used as a fining agent in a total amount of 100% for each of the above components.
It may be further contained in a range of 1 part by weight or less based on part by weight.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have developed an optical glass which does not use an arsenic compound or a fluorine compound which may affect the human body, has a high refractive index, a high dispersion and a light weight, and suppresses the deterioration of the coloring degree. As a result of intensive studies to obtain a glass component, SiO ₂ , Na ₂ O, BaO, TiO ₂ , Nb ₂ O ₅
It has been found that the above-mentioned objective optical glass can be obtained if at least is contained, and the present invention has been accomplished.

In the present invention, the type and combination of glass components are selected, and their contents are adjusted to solve the conventional problems as a whole. In particular, instead of containing arsenic compounds and fluorine compounds, TiO ₂ and Nb ₂ O ₅
It is a major feature that an appropriate amount of is contained to achieve high refractive index, high dispersion and light weight of the optical glass, and to suppress deterioration of the degree of coloring. That is, TiO ₂ has the effect of increasing the refractive index and dispersion, stabilizing the glass, and reducing the specific gravity of the glass. However, when the content of TiO ₂ is increased, the glass is colored. On the other hand, Nb ₂ O ₅ has the effect of increasing the refractive index and dispersion, and has the property that the glass is not colored even if the content is increased. But Nb ₂
O ₅ because a large specific gravity, the specific gravity of the glass becomes large when the content in a large amount. Therefore, in the present invention, TiO ₂ and Nb ₂ O
_By using in combination with ₅ , the high refractive index, high dispersion and light weight of the optical glass and suppression of deterioration in the degree of coloring were achieved.

The reason for limiting the components of the optical glass of the present invention will be described below. Unless otherwise specified,% means% by weight.

First, SiO ₂ is a main component forming an optical glass. When the content of SiO ₂ is less than 22.0%, the glass becomes unstable (devitrifies easily), and furthermore, it becomes easy to color. On the other hand, when the content exceeds 35.0%, it becomes difficult to obtain an optical glass having a high refractive index. Therefore, the content of SiO ₂ is set in the range of 22.0 to 35.0%. A more preferred content is 25.0-32.0%
Range.

Na ₂ O has an effect of improving the melting property of the glass and stabilizing the glass. Na ₂ O
If the content is less than 4.0%, such an effect cannot be obtained. On the other hand, if the content exceeds 17.0%, the desired optical constant cannot be obtained. Therefore, the content of Na ₂ O was increased to 4.0.
１７17.0%. A more preferred content is 1
The range is 2.0 to 14.0%.

BaO has the effect of increasing the refractive index and stabilizing the glass. If the content of BaO is less than 2.0%, such an effect cannot be obtained. On the other hand, if the content is 2
If it exceeds 5.0%, the specific gravity of the glass becomes too large.
Therefore, the content rate is set in the range of 2.0 to 25.0%.
A more preferred content is in the range of 9.0-17.0%.

TiO ₂ has the effect of increasing the refractive index and dispersion, stabilizing the glass, and reducing the specific gravity of the glass. If the TiO ₂ content is less than 18.0%, such an effect cannot be obtained. On the other hand, if the content is 2
If it exceeds 7.0%, the glass tends to be colored. Therefore,
The content was determined to be in the range of 18.0 to 27.0%. A more preferred content is in the range of 19.0 to 23.0%.

Nb ₂ O ₅ has the effect of increasing the refractive index and dispersion without causing coloring of the glass as much as TiO ₂ . If the content of Nb ₂ O ₅ is less than 13.0%, such an effect cannot be obtained. On the other hand, when the content rate is 2
If it exceeds 6.0%, the specific gravity of Nb ₂ O ₅ is too large, so that the specific gravity of the glass becomes too large. Therefore, the content is 13.
The range was defined as 0 to 26.0%. A more preferred content is in the range of 18.0 to 25.0%.

Also, K_TwoO, SrO, B_TwoO_Three, Al
_TwoO_Three, MgO, ZnO, Y_TwoO_Three, Ta_TwoO _Five, Li_TwoO,
ZrO_TwoOne or more specific amounts of
May also be contained. Why are you limited to these components?
Each is described below.

K ₂ O, like Na ₂ O, has the effect of improving the meltability of the glass and stabilizing the glass. However, if it is contained in a large amount, the desired optical constant may not be obtained.
Therefore the 8.0% upper limit of the content of K ₂ O, in addition K ₂
It is preferable that the total amount of O and Na ₂ O be in the range of 8 to 17%. A more preferred content of K ₂ O is 3.0 to 5.0.
%, More preferably the total amount is 9.0 to 13.0.
% Range.

SrO raises the refractive index like BaO,
It has the effect of stabilizing the glass. But 10.0%
If the content exceeds 0.1%, the glass tends to be devitrified. Therefore, the content is preferably 10.0% or less. A more preferred content is in the range of 3.0 to 4.0%.

B ₂ O ₃ promotes melting of the glass and stabilizes the glass. However, if the content exceeds 1.0%, the glass may be colored. Therefore, the content is preferably 1.0% or less. A more preferred upper limit of the content is 0.5%.

Al ₂ O ₃ improves the chemical durability of the glass, but if its content exceeds 2.0%, the viscosity may increase. Therefore, the content is preferably 2.0% or less. A more preferred upper limit of the content is 1.0%.

MgO, ZnO, Y ₂ O ₃ and Ta ₂ O ₅ are added for the purpose of adjusting the optical constants (refractive index and dispersion) of the optical lens according to the application. 3.0% of MgO and ZnO
If the content exceeds 3, the glass may be devitrified.
Therefore, the content of both MgO and ZnO is 3.0%.
The following is preferred. The more preferable upper limit of the content is 1.0%.
It is.

If Y ₂ O ₃ and Ta ₂ O ₅ are contained in an amount exceeding 3.0%, the glass may be devitrified. Therefore, the content of both Y ₂ O ₃ and Ta ₂ O ₅ is 3.0%.
The following is preferred. The more preferable upper limit of the content is 2.0%.
It is.

Li ₂ O has a role of adjusting the viscosity of the glass. However, if it is contained in excess of 3.0%, volatilization becomes intense, the composition fluctuates in the upper and lower portions of the glass, and striae tend to occur. . Therefore, the content is preferably 3.0% or less. A more preferred upper limit of the content is 1.0%.

ZrO ₂ improves the chemical durability of the glass, but if it is contained in excess of 4.0%, the glass tends to be rapidly devitrified. Therefore, the content is preferably 4.0% or less. A more preferred upper limit of the content is 3.0%.

As a fining agent, at least one of Sb ₂ O ₃ , SnO and SnO ₂ is used in a total amount of 100% for each of the above components.
You may make it contain in 1 part weight part or less with respect to a weight part. The content is set to 1 part by weight or less because if the content exceeds 1 part by weight, the glass may be colored. A more preferred upper limit of the content is 0.3 parts by weight.

If necessary, a conventionally known additive may be added in an appropriate amount as a glass component.

The method for producing the optical glass of the present invention is not particularly limited, and any known production method can be used. For example, oxides each corresponding as a raw material of each component,
Carbonates, nitrates, hydroxides and the like are used, weighed to a desired ratio, and sufficiently mixed with powder to prepare a blended raw material. This is put into, for example, a platinum crucible in an electric furnace heated to 1200 to 1300 ° C., melt-refined, homogenized by stirring, cast into a pre-heated iron mold, and gradually cooled to produce. Alternatively, continuous production may be performed using a continuous dissolution apparatus.

[0027]

EXAMPLES The present invention will be described more specifically with reference to the following examples. The present invention is not limited to these examples, and in the examples, “%” means “% by weight” unless otherwise specified.

Examples 1-10, Comparative Examples 1-6 Oxides, carbonates, nitrates, etc., which are glass raw materials, were mixed so as to have the target compositions shown in Tables 1 and 2, and thoroughly mixed with powder. To make a blended raw material,
Each sample was put into a platinum crucible in an electric furnace heated to 0 ° C., melted and clarified, stirred and homogenized, cast into a preheated iron mold, and gradually cooled to produce each sample. The refractive index (n _d ), Abbe number (ν _d ), and specific gravity of each sample for d-line were measured. These measurements were performed according to the test method of the Japan Optical Glass Industry Association Standard (JOGIS). As the coloring degree, the wavelength at which the spectral transmittance of a sample having a thickness of 10 mm gives 80% and 5%, respectively, was measured. The measurement results are shown in Tables 1 and 2.

[0029]

[Table 1] (Unit: wt%)

[0030]

[Table 2] (Unit: wt%)

Each of the optical glasses of Examples 1 to 10 having the structure of the present invention showed a high value of the refractive index of 1.800 or more and a high value of the dispersion of 23 to 27.
The specific gravity showed a small value of 3.60 or less. Further, λ ₈₀ and λ ₅ were excellent in non-coloring property, being 430 nm or less and 367 nm or less.

On the other hand, Comparative Examples 3 to 6 are conventional optical glasses, which have a high refractive index and a high dispersion, but contain 0.5% by weight of As ₂ O _3, which is liable to adversely affect the environment and the human body. % Or 0.2% by weight. In Comparative Examples 1 and 2, since the contents of TiO ₂ and Nb ₂ O ₅ were out of the specified range of the present invention, λ ₈₀ was 440 and 450 nm,
lambda ₅ is 380nm and the glass can be confirmed visually that the yellowish, was inferior to the non-coloring than in the previous examples.

[0033]

According to the optical glass of the present invention, S is expressed by weight%.
_{iO 2: 22.0~35.0%, Na 2} O: 4.0~1
7.0%, BaO: 2.0~25.0%, TiO 2: 1
_{8.0~27.0%, Nb 2 O 5:} 13.0~26.0%
, The refractive index is 1.80 to 1.85, the Abbe number is 23 to 27, the specific gravity is 3.60 or less, and the transmittance (80%) is obtained without using an arsenic compound or a fluorine compound. A high refractive index, high dispersion, light weight of 430 nm or less, and good coloring degree can be achieved.

Continued on the front page F term (reference) 4G062 AA04 BB01 DA04 DA05 DB01 DB02 DB03 DC01 DD01 DE01 DE02 DE03 DF01 EA01 EA02 EA03 EB03 EB04 EC01 EC02 EC03 ED01 ED02 ED03 EF01 EF02 EF03 EG03 EG04 FA01 FB04 FC01 FC01 FF04 FC01 FH02 FH03 FJ01 FJ02 FJ03 FK01 FL01 GA01 GA10 GB01 GC01 GD01 GE01 HH01 HH03 HH05 HH07 HH09 HH11 HH13 HH15 HH17 HH20 JJ01 JJ03 JJ04 JJ05 JJ07 JJ10 KK01 KK03 KK05 NN07 NN10

Claims (3)

[Claims] 1% by weight: SiO ₂ : 22.0 to 35.0%, Na ₂ O: 4.0 to 17.0%, BaO: 2.0 to 25.0%, TiO ₂ : 18. An optical glass containing 0 to 27.0% and Nb ₂ O ₅ : 13.0 to 26.0%. 2. K ₂ O: 8.0% or less (% by weight) (provided that the total amount of Na ₂ O and K ₂ O is 8.0 to 17.0)
%), SrO: 10.0% or less, B ₂ O _3: 1.0% or less, Al ₂ O _3: 2.0% or less, MgO: 3.0% or less, ZnO: 3.0% or less, Y ₂ O ₃ : 3.0% or less, Ta ₂ O ₅ : 3.0% or less, Li ₂ O: 3.0% or less, ZrO ₂ : 4.0% or less Claim 1 containing
The optical glass as described. 3. At least one of Sb ₂ O ₃ , SnO and SnO ₂ is used in an amount of 1 part by weight based on 100 parts by weight of the total amount of the above components.
The optical glass according to claim 1, further comprising not more than part by weight.