JP3458461B2 - Optical glass - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION_TwoO_Three−Li_TwoO-Z
nO-La_TwoO_ThreeAnd a refractive index (nd)
Is about 1.66 to 1.77, Abbe number (νd) is about 43 to
55. Further according to the invention
Optical glass can be molded at low temperatures, especially in molding
The present invention relates to an optical glass useful for molding. [0002] 2. Description of the Related Art In recent years, highly integrated equipment using an optical system has been developed.
High precision for optical systems as
There is a strong demand for miniaturization, light weight, and miniaturization.
Optical design using aspherical lens is becoming mainstream
is there. For this reason, aspherical lenses can be mass-produced at low cost.
It is necessary to supply a high-precision mold
Material (soft gob, polished flat glass or spherical surface
Pressure transfer to softened glass)
With the required performance without the need for complicated grinding and polishing processes
Research on molding technology to obtain
Was. Furthermore, not only aspherical lenses but also complex shapes are available.
Molding technology will be studied for lenses that do
It's getting bigger. Accordingly, it is suitable for molding.
The demand for the development of improved optical glass is increasing year by year
I have. As an optical glass having the above optical constants,
Is B_TwoO_Three, La_TwoO_ThreeVarious glasses with essential components
It has been known for a long time. However, the conventional B_TwoO_Three-La_Two
O_ThreeOptical glass containing
The emphasis is on improving durability and devitrification resistance, and hot forming
The moldability has not been sufficiently considered.
It is hard to say that it is suitable for the shape. In addition, these optical
Since laths generally have a high yield point,
Mold temperature is over 650 ° C, which causes high-precision mold deterioration.
It is difficult to realize a highly accurate lens surface.
You. Therefore, optical glass for molding with a low yield point
B_TwoO_Three, Li_TwoO, La_TwoO_ThreeThe main component
Various optical glasses have been developed and disclosed. For example,
JP-A-4-92834 discloses that nd = 1.622 to 1.7.
01, νd = 45.3 to 55.1.
Glass having At = 504-549 ° C.
No. 4-92835, nd = 1.740 to 1.78
5, νd = 38.0-47.0, At is 570 ° C. or less
(Example At = 500-569 ° C.)
Lass, JP-A-5-58669 discloses that nd = about 1.63.
1.75, vd = about 45-60, At = 555-640
Optical glass characterized by ° C, JP-A-5-201743
Means that nd = 1.65 to 1.75, νd is 50 or more, and At is
= 560 ° C. or lower. JP-A-62-87432 discloses that the Abbe number is
Although not disclosed, nd = 1.690-1.725,
At = 570 ° C. or lower and at a relatively low temperature containing PbO
Optical glass that can be precision pressed. [0005] [Problems to be solved by the present invention]
Optical glass, especially optical glass for molding, is heated
Specific elements in the glass composition volatilize during molding and adhere to the mold
This makes high-precision molding difficult.
There was a problem. Also, based on the results of analysis, etc.,
The elements to be deposited are mainly included to achieve a low yield point.
A relatively large amount of alkali metal oxide or lead oxide
I know that [0006] These elements make high-precision molding difficult.
Not only makes it difficult, but large amounts of alkali metal oxides
Oxides reduce environmental durability and lead oxides reduce environmental pollution during the manufacturing process.
There is also a problem that it goes on. Therefore, the present invention has been described above.
Various types of conventional optical glass, especially optical glass for molding
This was done in view of the problem. An object of the present invention is to provide a refractive index (nd) of 1.6.
6 to 1.77 and an optical constant of Abbe number (νd) of 43 to 55.
With a yield point of 620 ° C or less suitable for molding
In addition, the composition of the glass
Without emission, chemical durability, stability against devitrification
Providing new optical glass that is excellent and does not pollute the environment
It is. [0008] The inventor of the present invention has achieved the above object.
As a result of intensive research to achieve_TwoO_Three, Li_Two
O, ZnO, La_TwoO_ThreeOptical glass composition containing as an essential component
Is the desired optical constant and molding within a predetermined composition range.
Has a yield point suitable for molding
Excellent chemical resistance without volatilization of glass components
Of stability and stability against devitrification
Thus, the present invention has been accomplished. That is, the present invention
Ratio (wt%) SiO_Two        0 to 5 wt% B_TwoO_Three       22 to 35 wt% Al_TwoO_Three       0 to 5 wt% Li_TwoO 0.1 ~1.1wt% Na_TwoO 0 to 5 wt% K_TwoO 0 to 5 wt% However, Li_TwoO + Na_TwoO + K_TwoO 0.1-5.5wt% MgO 0 to 5 wt% CaO 0 to 10 wt% SrO 0-10 wt% BaO 0-10 wt% ZnO21.1~ 35 wt% ZrO_Two        0 to 5 wt% La_TwoO_Three      12 to 42 wt% Gd_TwoO_Three        0 to 20 wt% Y_TwoO_Three          0 to 10 wt% Yb_TwoO_Three        0 to 10 wt% Nb_TwoO_Five        0 to 10 wt% Ta_TwoO_Five        0 to 14 wt% As_TwoO_Three        0 to 1 wt% Sb_TwoO_Three        0 to 1 wt% Composition ofConsists of, Refractive index (nd) 1.66 to 1.7
7, Abbe number (νd) is 43 to 55, yield point (At) is
620 ° C. or lower, light for molding
Provide study glass. [0009] The above composition range has been found experimentally.
The reason for limiting the composition range is as follows. Si
O_TwoIs a glass-forming oxide and has stability against devitrification.
However, if it exceeds 5 wt%, undissolved matter is likely to be generated.
Increases the melting temperature and yield point. B_TwoO_ThreeIs SiO_TwoGlass forming oxidation as well
And an essential component in the present invention. 22wt%
If it is less than 3, sufficient stability against devitrification cannot be obtained.
If it exceeds 5% by weight, the refractive index decreases and the chemical durability decreases.
Let it down. Al_TwoO_ThreeIs stability against devitrification, chemical durability
The yield point is increased when the content exceeds 5 wt%.
Let Li_TwoO compared to other alkali metal oxides
Without significant decrease in refractive index and chemical durability
It is an essential component that lowers the melting temperature and yield point
However, if the content is less than 0.1 wt%, a sufficient effect cannot be obtained.
If it exceeds 5 wt%, it is stable against chemical durability and devitrification.
Is reduced. Furthermore, Li_TwoO volatilizes during molding and forms
It easily adheres to the mold, making high-precision molding difficult.
You. Na_TwoO, K_TwoO lowers melting temperature and yield point
However, if it exceeds 5 wt%, the refractive index decreases,
The durability and stability against devitrification are also reduced. further,
Na _TwoO, K_TwoO volatilizes during molding and easily adheres to the mold
And high-precision molding is difficult. However, Li_Two
O, Na_TwoO, K_TwoThe total amount of O exceeds 5.5 wt%
Lowering the refractive index reduces chemical durability and devitrification.
Stability is also reduced. In addition, these alkali metal acids
The compound volatilizes during molding and easily adheres to the mold.
Molding becomes difficult. . Although MgO lowers the melting temperature, 5 wt.
%, The stability against devitrification decreases, and the phase separation tendency also increases.
Increase. CaO, SrO, and BaO adjust or reduce the refractive index.
Useful for improving stability against permeability, but exceeding 10 wt%
Conversely, the tendency to devitrification increases, reducing chemical durability
You. ZnO lowers the melting temperature and yield point,
An essential component that is also effective in adjusting the refractive index, but 20 wt%
If the amount is less than 35%, sufficient effects cannot be obtained.
Greater dispersion, lower stability against devitrification,
Target durability also decreases. ZrO_TwoIs stability against devitrification,
Improves chemical durability, but over 5 wt%, reverse
The tendency to devitrification increases, and the yield point also increases. La_TwoO_ThreeIs relatively stable against devitrification
Without lowering, increase the refractive index and increase the chemical durability
An essential component to improve, but less than 12 wt% is sufficient
Effect cannot be obtained.
The stability decreases and the yield point increases. Gd_TwoO_ThreeIs relatively
The refractive index without lowering the stability against devitrification
To increase the chemical durability, but exceed 20 wt%
Lowers the stability against devitrification and increases the yield point
You. Y_TwoO_Three, Yb_TwoO_ThreeIncreases the refractive index,
Durability is improved, but devitrification occurs when it exceeds 10 wt%
Stability decreases and the yield point also increases. Nb_TwoO_Five,
Ta_TwoO_FiveIncreases the refractive index and improves the chemical durability
However, if they exceed 10 wt% and 14 wt%, respectively,
And the stability against devitrification also decreases. As_TwoO_Three, Sb_TwoO_ThreeIs used as a defoamer
However, a sufficient effect can be obtained at 1 wt% or less. Ma
Sb_TwoO_ThreeExceeds 1 wt%, coloring of glass is recognized
Can be [0018] EXAMPLES Hereinafter, the present invention will be described more specifically by way of examples.
Explain, but the invention is not limited to these examples
Absent. Example composition (numerical value is wt%) according to the present invention
The scientific constant (nd, νd) and the yield point (At, numerical value is ° C)
All are shown in Tables 1, 2 and 3.However, in Table 1, No.
Nos. 1, 5, 6, and 2 in Table 2. 8, 10 and No. 3 in Table 3.
15 is excluded from the working composition examples. The optical glass according to the present invention is a raw material for each component.
Use the corresponding oxides, carbonates, nitrates, etc.
Weigh to the desired ratio, mix well with powder and mix
And heated to, for example, 1050 to 1300 ° C.
Into a platinum crucible in an electric furnace that has been melted and clarified.
And cast into a preheated iron mold,
Can be manufactured. [0020] [Table 1][0021] [Table 2][0022] [Table 3][0023] As described above, according to the present invention, the refractive index
(Nd) is 1.66 to 1.77, Abbe number (νd) is 4
3-55, that the yield point (At) is 620 ° C or less
Features, excellent chemical durability, stability against devitrification,
An optical glass free of environmental pollution is provided. Moreover, the optical glass according to the present invention has a yield point
Is low, especially when the high-precision mold surface is added to the glass material.
Pressure transfer and specified without final grinding / polishing process
Very useful for molding to obtain lenses with excellent performance
It is for.

Claims (1)

(57) [Claims] [Claim 1] SiO ₂ 0 to 5 wt% B ₂ O ₃ 22 to 35 wt% Al ₂ O ₃ 0 to 5 wt% Li _{2 in} weight ratio (hereinafter referred to as wt%) O 0.1 to 1.1 wt% Na ₂ O 0 to 5 wt% K ₂ O 0 to 5 wt% However, Li ₂ O + Na ₂ O + K ₂ O 0.1 to 5.5 wt% MgO 0 to 5 wt% CaO 0 ~ 10 wt% SrO 0 ~ 10 wt% BaO 0 ~ 10 wt% ZnO 21.1 ~ 35 wt% ZrO 2 0 ~ 5 wt% La 2 O 3 12 ~ 42 wt% Gd 2 O 3 0 ~ 20 wt% _{Y 2 O 3 0 ~ 10 wt} % Yb 2 O 3 0 ~ 10 wt% Nb 2 O 5 0 ~ 10 wt% Ta 2 O 5 0 ~ 14 wt% As 2 O 3 0 ~ 1 wt% Sb 2 O 3 0 -1 wt%, and a refractive index (nd) of 1.66-1.7.
7. An optical glass characterized by having an Abbe number (νd) of 43 to 55 and a yield point (At) of 620 ° C. or less.