JPS63265840A - Optical glass - Google Patents

Abstract

PURPOSE:To obtain optical glass which has high diffusivity and is improved in coloring and devitrification tendency and is mass-producible by limiting componental composition and especially allowing the specified amount of SiO2, B2O3, P2O5, TiO2 and Nb2O5 to be contained. CONSTITUTION:Optical glass is obtained by allowing by wt.% 5-55% SiO2, 0.5-15% B2O3, 0.5-30% P2O5, 1-35% TiO2, 1-50% Nb2O5, 0-5% ZnO, 0-5% PbO, wherein ZnO+PbO=0.1-5%, 0-5% Li2O, 0-25% Na2O, 0-30% K2O, wherein Li2O+Na2O+K2O=17.5-30%, 0-5% MgO, 0-5% CaO, 0-5% SrO, 0-5% BaO, 0-3% ZrO2, 0-6% Al2O3, 0-2% As2O3, 0-2% Sb2O3 and 0-10% fluoride of metal of one or more kinds of the above-mentioned respective metallic oxides as total amount expressed in terms of F to be contained. Further in order to maintain prescribed chemical constant and to obtain excellent resistance to devitrification, total amount of SiO2, B2O3 and P2O5 is regulated to 55% or below more preferably.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides an optical system with optical constants having a refractive index (nd) of approximately 1.59 to 1.82 and an Abbe number (νd) of approximately 20 to 40. , has excellent light transmission properties and stability against devitrification, and is basically SiO2-B203-P205-TiO2-
Nb205-R20-ZnO and/or pbo-based (
R relates to an optical glass having extremely high dispersibility and consisting of one or more of Li, Na, and K.

[Prior Art] Conventionally, as a glass having the above-mentioned optical constants,
TiO2 and/or silicate glass or phosphate glass
Alternatively, glass containing Nb2O5 is known.

For example, in Japanese Patent Application Laid-open No. 48-65211, S i
02-B203- to 20 series, Ti as an optional component
Although a glass to which T i 02 can be added is disclosed, in a high dispersion region, since a large amount of T i 02 is added, coloration is large and devitrification resistance 5 is insufficient.

Also, in Japanese Patent Application Laid-open No. 50-71708, P205-
PbO-Nb20s-divalent metal oxide glass is disclosed in JP-A-52-132012 as P205-B20.
3-Nb20s glasses have been disclosed, but these glasses have inferior mechanical properties such as abrasion resistance and hardness, making it difficult to obtain surface precision during glass processing and being easily scratched. or Further, since it contains a large amount of PbO or Nb2O5, it has drawbacks such as large coloring.

In Japanese Patent Publication No. 43-7121, SiO2-P205
-T i 02-R20 and/or R'O system (R'
(Alkaline earth metal) glass has been disclosed, however, it has the drawbacks of large devitrification and coloration due to the inclusion of a large amount of TiO2.

Furthermore, in Japanese Patent Application Laid-open No. 54-105119, S i
02-Ti02-R20-BPO4 and/or A
l (PO3) 3 type glass was published in Japanese Patent Application Laid-Open No. 55-5173.
In Publication No. 2, SiO2-Ti02-R20-BPO+
and/or AI(PO3) 3-Nb2O5 glasses have been disclosed, but these glasses have insufficient stability against devitrification and light transmission properties.

[Problems to be Solved by the Invention] An object of the present invention is to provide an optical glass that has the above-mentioned predetermined optical constants and that comprehensively eliminates the various drawbacks found in the above-mentioned conventional techniques. shall be.

[Means for Solving the Problems] In order to achieve the above object, the present inventors have conducted extensive testing and research, and have found that SiO2-B203 has a specific composition range that is not specifically disclosed in conventional technical documents. -P205-T
i02-Nb205-R20-ZnO and/or P
We have discovered that it is possible to obtain a bO-based glass that can be mass-produced and that maintains extremely high dispersibility while also having improved coloring and devitrification tendencies, and has thus completed the present invention.

The characteristics of the optical glass according to the present invention are that, in weight %, Si
025-55%, 82030.5-15%, P2O50
, 5-30%, Ti021-35%, Nb2o51-5
0%, Zn0O~5%, Pb00~5%, however, ZnO
+Pb0=0.1-5%, Li2O0-5%, Na20
0-25%, K2O0-30%, however, Li2O+Na
20+ to 20= 17.5~30%, Mg0O~5%,
Ca0 0-5%, Sr00-5%, Ba0O-5%,
ZrO 20-3%, A 12 03 0-6%, A
s203 0 to 2%, s b2 o3 o to 2%, and a fluoride of one or more metals among the above metal oxides, in a total amount of F of 0 to 10%.

The reason for limiting the composition range of each component as described above is as follows.

That is, the S i 02 component, which is a glass-forming saponified product, is effective in maintaining good mechanical properties and thermal expansion coefficient. However, if the amount is less than 5%, the refractive index and thermal expansion coefficient tend to be excessive, and the mechanical properties tend to deteriorate. Further, if the amount is too large, it becomes difficult to obtain the required refractive index, so the amount is set to 55% or less, preferably 45% or less.

Each component of B2O3 and P2O5 has higher dispersion as a glass skeleton component than SiO2, and is also effective in adjusting the viscosity of the glass. Of these, B2O3
has the effect of suppressing the opalescence that occurs when a large amount of P2O5 is contained, but if the amount of P2O5 is less than 0.5%, the effect is not sufficient, and if it exceeds 15%, the chemical durability deteriorates. and discoloration. On the other hand, P2O5 is
Although it is effective in improving chemical durability against acids, if the amount is less than 0.5%, the effect is insufficient, and if it exceeds 30%, the mechanical properties may deteriorate significantly. During melting, the amount of volatilization increases, making it difficult to obtain homogeneous glass.

In addition, in order to maintain predetermined optical constants and obtain excellent devitrification resistance, S i 02 , B203 and TiO2
and Nb2O5 are effective components for imparting high dispersion performance to glass. Furthermore, Nb2O5 is effective in suppressing the tendency of glass to devitrify. However, TiO
If the amount of 2 is less than 1%, the required optical constants will be poor, and if it exceeds 35%, the glass will be markedly colored and the tendency to devitrify will increase. Further, the amount of Nb2O5 is required to be at least 1% or more in order to obtain the required optical constants, but if it exceeds 50%, the tendency to devitrify increases.

ZnO and PbO are important components that have been unexpectedly found to suppress the increase in coloration and devitrification tendency caused by the addition of TiO2 and Nb2O5 by introducing small amounts of them into the glass of the present invention. It is also effective in improving the melting properties of glass. In order to exhibit these effects, the amount of ZnO and/or PbO is required to be 0.1% or more, but if it exceeds 5%, it may lead to deterioration of chemical durability or even cause devitrification or discoloration. may be accompanied by an increase in

Each component is Li2O, Na2O and Ni20(7).

It is an effective component not only as a glass fluxing agent but also in suppressing devitrification tendency and coloring. However, if the total amount of one or more of these components is less than 17.5%, their effects may not be sufficient, and if each of these components
%, 25% and 30% or in total 30%
If it exceeds %.

This is not preferable because it tends to deteriorate the chemical durability of the glass and increase its tendency to devitrify, and it also tends to involve significant volatilization of these components during melting.

In the glass of the present invention, in addition to the above components, the following components may be optionally added to improve the stability, chemical durability, mechanical properties, etc. of the glass, and adjust the optical constants, viscosity, etc. Can be done.

That is, alkaline earth metal oxides such as MgO1Cab, SrO, and BaO are effective in suppressing the tendency to devitrify.

However, if each exceeds 5%, chemical durability tends to deteriorate or it becomes difficult to obtain predetermined optical constants. ZrO2 is effective in improving the chemical durability of glass, but if it exceeds 3%, the tendency for devitrification increases.

Al2O3 is effective in adjusting the viscosity of glass, improving devitrification resistance and chemical durability, and contains a part of 5to2 and 6%
You can replace up to As2O3 and 5b2o3 are effective as glass refining agents, but up to 2% of each is sufficient. Furthermore, the metal fluorides of each of the metal oxides mentioned above are effective in adjusting the refractive index and viscosity of glass, but if these fluorides exceed 10% as a total amount of F, glass melting will be affected. At this time, the volatilization of the F component increases and the glass becomes more likely to devitrify.

Furthermore, if necessary, other components such as Rb2O and/or Cs2O may be added to the glass of the present invention up to about 10%, such as I B203 and G e02 .

5n02, Bi203, TeO2 and La2O3
It is acceptable to add up to a total of about 5% of one or more components such as.

[Example] Next, examples will be described.

Table 1 shows preferred examples (No.
1 to 6) and comparative examples of conventional technology (No, A to E),
The refractive index (nd), Atsube number (νd) of these glasses,
This is shown together with the devitrification test results and the 80% transmission wavelength. Here, no.

l, 2 and No, A, B, No, 3 and No, C, No, 4
．． 5 and No, D and No, 6 and No, E are comparisons of glasses having almost the same optical constants Table 1
The devitrification test results for the pre-mixed raw material batch,
1150-1300 depending on the difficulty of melting of each glass
This is the result of observing a sample that was melted at 1100°C, poured into a mold, held in a slow cooling furnace at 600°C for 2 hours as annealing conditions, and then cooled down. Also, 80%
The transmission wavelengths are those measured using a spectrophotometer on a double-sided polished sample of 10 cm thick obtained from each glass (the numbers in parentheses are the values in the prior art data).

Further, Table 2 shows other preferred embodiments of the present invention along with their optical constants. In addition, the content of Example No. 36 and 20 in Table 1-2 is K2Ti
When converted to F6 by 20, it becomes 21.4% by weight.

(Left below) As shown in Table 1, conventional glass comparative example No.
A, D, and E were devitrified immediately after casting or during annealing, whereas Example No. of the present invention had almost the same optical constants as these.

l and 2. Glasses No. 4 and 5 and No. 6 are:
All were transparent. In addition, compared to conventional glasses No. B, No. 2, and No. C, glasses No. 001 and 2 of the present invention and No.
The 80% transmission wavelength of No. 3 is shifted to a shorter wavelength region, and the colorability is improved.

In addition, all of the glasses according to the embodiments of the present invention shown in Table 1-2 satisfy predetermined optical constants, and, like the glasses according to the embodiments of the present invention shown in Table 1, have excellent devitrification resistance and light transmission. It has excellent characteristics.

Note that the glasses of the examples of the present invention listed in Tables 1 and 2 all have improved wear resistance and hardness, and are excellent in machinability.

The glass of the composition example of the present invention is produced by putting the raw materials into a platinum crucible, etc., melting, clarifying, and homogenizing them at 1,100 to 1,400°C, and then pouring them into a mold, etc. preheated to an appropriate temperature, and slowly cooling them. Therefore, it can be easily manufactured.

[Effects of the Invention] As described above, the optical glass of the present invention has a new specific composition range of S i 02-B203-P2O3-T i
02-N b205-R20-Z Since it is a no and/or PbO glass, the refractive index (nd) is approximately 1.5.
It has an optical constant of 9 to 1.82 and an Atsubbe number (νd) of about 20 to 40, and has excellent light transmittance performance compared to conventional glass, less coloring, and stability against devitrification. It has been improved and is suitable for mass production.

Claims (2)

[Claims] (1) In weight%, SiO_2 5-55%, B_2O_3 0.5-15%, P_2O_5 0.5-30%, TiO_2 1-35%, Nb_2O_5 1-50%, ZnO 0-5%, PbO 0- 5%, however, ZnO + PbO = 0.1 to 5%, Li_2O 0 to 5%, Na_2O 0 to 25%, K_2O 0 to 30%, However, Li_2O + Na_2O + K_2O = 17.5 to 30%, MgO 0 to 5%, CaO 0 to 5%, SrO 0 to 5%, BaO 0 to 5%, ZrO_2 0 to 3%, Al_2O_3 0 to 6%, As_2O_3 0 to 2%, Sb_2O_3 0 to 2%, and one of the above metal oxides. An optical glass characterized by containing 0 to 10% of the above metal fluorides as a total amount of F. (2) SiO_2 5-45%, SiO_2+B_2O
The optical glass according to claim 1, characterized in that _3+P_2O_5 is 55% or less.