JPH09188540A - Optical glass free from solarization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical glass having excellent light transmission and at the same time excellent in solarization resistance by limiting the content of MoO3 in an optical glass of P2 O5 -Nb2 O5 . SOLUTION: This optical glass is a P2 O5 -Nb2 O5 optical glass whose MoO3 content is limited at 30ppm or less by weight. A Mob3 content of 30ppm or less by weight and a Sb2 O3 content of 0.05-0.3wt.% are preferable since these contents can further improve solarization resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical glass without solarization, which is used as an optical material for lenses and prisms.

[0002]

2. Description of the Related Art Conventionally, various glass systems have been known as a high refractive glass containing a P ₂ O ₅ component. For example, P ₂
O ₅ -TiO ₂ -Nb ₂ O _{5 based, P 2 O 5 -B 2 O} 3 -TiO 2
-Nb ₂ O ₅ system and the like are known, but since these glass systems contain a large amount of TiO ₂ component, the obtained glass is colored purple and thus has insufficient light transmittance, and thus optical glass. Is unsuitable as Japanese Unexamined Patent Publication No. 5-270853 is disclosed to solve these problems.
This glass has insufficient solarization resistance.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical glass without solarization that comprehensively solves the above-mentioned drawbacks of the prior art.

[0004]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the inventors of the present invention have conducted earnest tests and have found that MoO ₃
It was found that a glass having a content of 30 ppm or less is an optical glass having a surprisingly excellent light transmittance and an excellent solarization resistance, and has completed the present invention.

That is, the invention described in claim 1 is P ₂
In the O ₅ -Nb ₂ O ₅ -based optical glass without solarization, the content of MoO ₃ is 30 ppm or less by weight.

According to a second aspect of the present invention, in the optical glass, the MoO ₃ content is 30 ppm or less and the Sb ₂ O ₃ content is 0.05 to 0.3% by weight. Is.

According to a third aspect of the present invention, in the optical glass, by weight, P ₂ O ₅ 5 to 60%, TiO ₂ 0 to 25%, B ₂ O ₃ 0 to 20%, SiO ₂ 0 to 30 are used. _{%, Nb 2 O 5 5~60%} , Ta 2 O 5 0~20%, WO 3 0~10%, Bi 2 O 3 0~10%, ZrO 2 0~ 5%, Al 2 O 3 0~ 5 %, MgO + CaO + SrO + BaO 0-20%, La ₂ O ₃ + Y ₂ O ₃ + Gd ₂ O ₃ 0-20%, ZnO 0-20%, Li ₂ O + Na ₂ O + K ₂ O 0-35%, but Li ₂ O 0- 8%, Na ₂ O + K ₂ O 0-35%, and a total of 0-8 as a fluoride (F) substituted with a part or all of one or more oxides of the above metal elements.
% Is included.

In the optical glass without solarization according to the present invention, the reason for limiting the content of MoO ₃ to 30 ppm or less is that the excellent light transmittance is maintained and the solar resistance is excellent as described above. This is the upper limit of the content for obtaining the glass, and if it exceeds 30 ppm, the above effect is deteriorated. More preferably, if the Sb ₂ O ₃ content is limited to the range of 0.05 to 0.3%, the effect of solarization resistance is further improved.

The P ₂ O ₅ component is an important component as a glass-forming oxide, and it is more preferable that it is added in an amount of 5% or more because it is an effective component for imparting high dispersibility to glass. It is even more preferable to set the upper limit to 60% for maintenance.

The TiO ₂ component can be added because it is an effective component for increasing the refractive index of glass, but it is more preferable to add up to 25%.

The B ₂ O ₃ component and the SiO ₂ component may be added in order to maintain the meltability of the glass, but it is more preferable that the amounts thereof are 20% and 30%, respectively, in order to prevent the devitrification tendency. .

The Nb ₂ O ₅ component is an effective component for vitrifying a wide range to give high dispersibility to the glass.
It is even more preferable to limit the content to 0% in order to maintain the devitrification resistance of the glass.

The components of Ta ₂ O ₅ , WO ₃ and Bi ₂ O ₃ are effective components for increasing the refractive index of glass,
It is more preferable that these amounts be 20%, 10% and 10%, respectively, in order to maintain the devitrification resistance of the glass.

Each of the ZrO ₂ and Al ₂ O ₃ components is effective in improving the chemical durability of the glass, but it is more preferable that the content of each component be up to 5% in order to maintain devitrification resistance.

Each of the components MgO, CaO, SrO and BaO is effective in suppressing devitrification of glass.
More preferably, the total amount of one kind or two or more kinds is up to 20%.

Each of the La ₂ O ₃ , Y ₂ O ₃ and Gd ₂ O ₃ components may be added to improve the chemical durability, but the total amount of one or more of these components is 20%. Is more preferable.

The ZnO component can be added to improve the meltability, but it is more preferable to add up to 20%.

The respective components of Li ₂ O, Na ₂ O and K ₂ O can be added arbitrarily because they have the effect of improving the melting property and the light transmittance of the glass, but one or more of them in total may be added. More preferably, it is up to 35%. However,
It is even more preferable that the Li ₂ O component be up to 8% in order to maintain the devitrification resistance. Further, the Na ₂ O and K ₂ O components improve the high dispersibility of the glass and can be contained in the glass in a stable manner. However, the total amount of one or two of them can maintain the chemical durability. Therefore, up to 35% is even more preferable.

A fluoride obtained by substituting a part or all of one or more oxides of each of the above metal elements is effective because it has the effect of improving the light transmittance of glass, but it is effective for maintaining devitrification resistance. Therefore, it is even more preferable that the total amount of these fluoride components as fluorine (F) is up to 8%.

[0020]

EXAMPLES Examples of the present invention will now be described with reference to the glass composition, glass refractive index (nd), Abbe number (νd), and light wavelengths (λ ₁ , λ ₂ ) at 70% of the spectral transmittance curve before and after ultraviolet irradiation. ) And the difference between the two (△ λ; a measure of the magnitude of solarization)
Is shown in Table 1 together with a comparative example of conventional glass. Where T ₇₀
Shows the result of measurement on a glass sample having a thickness of 10 m / m, which was polished on both sides.

[0021]

[Table 1]

[Table 1]

As can be seen from Table 1, the solarization (Δλ) of the conventional glass was 90 nm, whereas the glass No. 1 of the example of the present invention was used. 1 to No. (Δλ) of 7 was suppressed to 2 nm or less. Further, when the 70% transmittance wavelength is observed, it is understood that the glass of the present invention still retains excellent light transmittance.

The glass of each of the above-mentioned examples of the present invention is prepared by weighing and mixing the usual optical glass raw materials such as carbonates, nitrates, phosphate oxides and fluorides, and mixing them, which are then used in a quartz crucible or a platinum crucible. About 1000 to 1300 ℃
It can be easily produced by melting in about 2 to 5 hours, defoaming, homogenizing by stirring, and then casting in a mold and cooling.

[0024]

As described above, since the optical glass of the present invention has a MoO ₃ content of 30 ppm or less, it has little coloration, excellent light transmittance, and excellent solarization resistance. Therefore, it is more useful than conventional glass.

[Brief description of the drawings]

The graph of FIG. 1 shows the relationship between the MoO ₃ content in glass and solarization (Δλ). Apparently, the glass of the present invention has excellent solarization resistance.

Claims (3)

[Claims] 1. A P ₂ O ₅ -Nb ₂ O ₅ based optical glasses, by weight, optical glass without solarization, wherein the content of MoO ₃ is 30ppm or less. 2. The content of MoO ₃ is 30 ppm by weight.
Below, and the content of Sb ₂ O ₃ is 0.05 to 0.3%
The optical glass according to claim 1, wherein the optical glass is in the range. 3. By weight, P ₂ O ₅ 5-60%, TiO ₂ 0-25%, B ₂ O ₃ 0-20%, SiO ₂ 0-30%, Nb ₂ O ₅ 5-60%, Ta. ₂ O ₅ 0-20%, WO ₃ 0-10%, Bi ₂ O ₃ 0-10%, ZrO ₂ 0-5%, Al ₂ O ₃ 0-5%, MgO + CaO + SrO + BaO 0-20%, La ₂ O _{3 + Y 2 O 3 + Gd 2} O 3 0~20%, 0~20% ZnO, Li 2 O + Na 2 O + K 2 O 0~35%, _{however, Li 2 O 0~ 8%,} Na 2 O + K 2 O 0~35% , And a total of 0 to 8 as a fluoride (F) substituted with a part or all of one or more oxides of the above metal elements.
%, And the optical glass according to claim 1 or 2.