JP3458462B2 - Optical glass - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION_TwoO_Three−Li_TwoO-Z
nO-La_TwoO_Three -Gd _Two O _Three Refraction
Rate (nd) is about 1.68 to 1.80, Abbe number (νd)
Is about 44-53. In addition, the book
The optical glass according to the invention can be formed at a low temperature,
Particularly, 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. [0004] Therefore, for molding a mold having a low yield point.
As optical glass, B_TwoO_Three, Li_TwoO, La_TwoO_ThreeThe main
Various optical glasses have been developed and disclosed.
For example, Japanese Patent Application Laid-Open No. 4-92834 discloses that nd = 1.622.
~ 1.701, νd = 45.3 ~ 55.1,
Optical glass having At = 504 to 549 ° C. in Examples
And Japanese Patent Application Laid-Open No. 4-92835, nd = 1.740.
1.785, νd = 38.0-47.0, At is 570
° C or less (Example At = 500-569 ° C)
Optical glass, Japanese Patent Application Laid-Open No. Hei 5-58669, nd = about 1.
63-1.75, vd = about 45-60, At = 555
Optical glass characterized by 640 ° C., JP-A-5-2017
No. 43, nd = 1.65 to 1.75, vd is 50 or more
Optical glass or the like characterized by At = 560 ° C. or less.
You. Japanese Patent Laid-Open No. 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. [0006] [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 [0007] 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. It is an object of the present invention that the refractive index (nd) is 1.6.
8 to 1.80 and an optical constant of Abbe number (νd) of 44 to 53.
With a yield point of 630 ° C or less suitable for molding
In addition, a large amount of glass composition
No volatilization, chemical durability and devitrification
Providing new optical glass with excellent qualities and no environmental pollution
Is Rukoto. [0009] 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_Three, Gd_TwoO_ThreeOptics with essential components
The glass composition has a desired optical property within a predetermined composition range.
With a yield point suitable for molding and molding,
Excellent without evaporating the glass composition during molding
High chemical durability and stability against devitrification
And found the present invention. That is, the present invention
Is the weight ratio (hereinafter wt%), SiO_Two0 to 5 wt% B_TwoO_Three20 to 30 wt% Al_TwoO_Three      0 to 5 wt% Li_TwoO 0.1 ~ 2.5wt% Na_TwoO 0 to 5 wt% K_TwoO 0 to 5 wt% However, Li_TwoO + Na_TwoO + K_TwoO 0.1-7.0 wt% MgO 0 to 5 wt% CaO 0 to 10 wt% SrO 0-10 wt% BaO 0-10 wt% ZnO 1 to 19.5 wt% ZrO_Two        0 to 8 wt% La_TwoO_Three     16 to 42 wt% Gd_TwoO_Three 10    ~ 25 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 15 wt% As_TwoO_Three       0 to 1 wt% Sb_TwoO_Three       0 to 1 wt% Composition ofConsists ofAnd the refractive index (nd) is 1.68 to 1.8.
0, Abbe number (νd) 44-53, yield point (At)
630 ° C. or lower light for molding
Provide study glass. [0010] 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. 20wt%
If it is less than 3, sufficient stability against devitrification cannot be obtained.
If it exceeds 0 wt%, the refractive index decreases and the chemical durability decreases.
To 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 7.0 wt%
Lowering the refractive index reduces chemical durability and devitrification.
Stability is also reduced. In addition, these alkali metal oxidations
The object volatilizes during molding and easily adheres to the molding die.
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 less than 1 wt%
If it is full, sufficient effect cannot be obtained, and it exceeds 19.5 wt%
And dispersion become large, the stability against devitrification decreases, and
The mechanical durability also decreases. ZrO_TwoIs stable against devitrification
Improves performance and chemical durability, but exceeds 8 wt%
Conversely, the tendency of 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 16 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
Higher and improve chemical durabilityIs an essential ingredientBut,
If it exceeds 25% by weight, stability against devitrification decreases, and
The dip also rises. 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 15 wt%, respectively,
And the stability against devitrification also decreases. As_TwoO_Three, Sb_TwoO_ThreeIs used as a defoamer
However, sufficient effects can be obtained with 1 wt% or less.
You. Also, Sb_TwoO_ThreeIs colored to glass when it exceeds 1 wt%
Is recognized. [0019] 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)
Both are shown in Tables 1 and 2.However, in Table 1, No. 3 and
No. in Table 2 8 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, 1100-1300 ° 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. [0021] [Table 1][0022] [Table 2][0023] As described above, according to the present invention, the refractive index (n)
d) is 1.68 to 1.80, Abbe number (νd) is 44 to
53. The yield point (At) is 630 ° C. or less
And has excellent chemical durability and stability against devitrification.
A contamination-free optical glass 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 20 to 30 wt% Al ₂ O ₃ 0 to 5 wt% Li ₂ O 0.1 to 2.5 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 7.0 wt% MgO 0 to 5 wt% CaO 0 １０10 wt% SrO 0 １０10 wt% BaO 0 １０10 wt% ZnO 1 １９19.5 wt% ZrO ₂ 0 ８8 wt% La ₂ O ₃ 16 ４２42 wt% Gd ₂ O ₃ 10 ２５25 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 ~ 15 wt% As 2 O 3 0 ~ 1 wt% Sb 2 O 3 0 ~ 1 wt% and a refractive index (nd) of 1.68 to 1.8.
An optical glass characterized by having an Abbe number (νd) of 44 to 53 and a sag point (At) of 630 ° C. or less.