JP2002114536A - Ultraviolet ray resistant glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical material which suppresses the formation of coloring sites due to UV absorption and can be used in the UV region. SOLUTION: The UV resistant glass comprises, by mol, 3-65% SiO2, 5-70% B2O3, 15-50%, in total, of one or more selected from LiF, NaF and KF, 0-20% AlF3, 0-20% MgF2, 0-20% CaF2, 0-20% SrF2, 0-20% BaF2, 0-20% YF3 and 0-20% LaF3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet resistant glass, and more particularly to a glass whose transmittance is not reduced by irradiation of ultraviolet rays, and more particularly to an ultraviolet resistant glass suitable for use as an optical element in the ultraviolet region or an optical fiber for transmitting ultraviolet light. .

[0002]

2. Description of the Related Art A multi-component glass such as an optical glass or a plate glass absorbs high-energy light such as ultraviolet light to form a coloring center, and the transmittance decreases from the visible region to the ultraviolet region. Such a so-called solarization is considered to be one of the properties to be evaluated especially in optical glass, and an evaluation method is determined (JOGIS 04-1994, Japan Optical Glass Industrial Association Standard). According to this standard, solarization is evaluated by irradiating glass with a fixed amount of ultraviolet light using a high-pressure mercury lamp and measuring the transmittance before and after irradiation, and the rate of change (decrease in transmittance) according to this standard. Is done by asking for

[0003] Conventionally proposed ultraviolet transmitting glass
JP-A-60-77144, JP-A-60-218
No. 30, JP-A-60-200842.
SiO like_Two-B_TwoO_Three-Al_TwoO_Three-Na_Two
There are many O-based glasses. These are used for UV lamps
Main applications are glass tubes. For example,
No. 60-77144 discloses SiO 2_Two56-70%,
B_TwoO_Three16-35%, Na_TwoO4.7-13.0%,
Na_TwoO / B_TwoO_Three<0.55, SiO_Two+ B _TwoO_Three+
Na_TwoO + Al_TwoO_Three≧ 95% and oxygen ions
2.5 to 10% by weight of the composition
Having a composition containing fluorine to improve ultraviolet transmission performance
And can be fused to alumina package for semiconductor
A glass for the purpose is described. That is, this
These glasses are composed of SiO_TwoBecause of the large amount, the volatility of the F component
It has the characteristic that the number of departures increases. Thus, F
Unless the components remain in the glass, the UV resistance is not at all expected
I can't wait. To do this, we need to dissolve at the lowest possible temperature.
A composition system that can be used is desirable. From such a thing
The light composition is SiO_TwoSelect a composition with low
The F component was increased. In the substantial composition of the present invention, F is 1
0% by mass, SiO_TwoIs about 50% by mass.

[0004]

Regarding the coloring phenomenon of glass by ultraviolet rays, "Glass Handbook" No. 838-
840 pages (Asakura Shoten, first edition issued on September 30, 1975)
Describes a long-standing study on the mechanism of formation of colored centers in glass. This coloring phenomenon
It is considered that there are many cases in which colored ions are mainly generated and defects in the glass structure change to colored centers in many cases.
In the case of the colored ion, the following mechanism works. Heavy metal ions are included as impurities in the multi-component glass, and an oxidation-reduction reaction occurs between such metal ions due to light absorption, for example, an oxidation-reduction reaction as shown in (1) occurs.

[0005]

[Formula 1] Mn ²⁺ → Mn ³⁺ + e ⁻ Fe ³⁺ + e ⁻ → Fe ²⁺ (1)

[0006] Mn ²⁺ has a small absorption coefficient and has little effect on thin glass. However, since Mn ³⁺ has an absorption band in the visible region and has a large absorption coefficient, coloring can be clearly recognized even with thin glass. In this way, ions having a large absorption coefficient are generated by the photoreaction, causing coloring.

[0007] In this case, it is considered that the non-crosslinked oxygen present in the glass absorbs ultraviolet rays to emit electrons, and changes to a color center. Such non-crosslinked oxygen also reduces the transmittance in the ultraviolet region. Coloring with metal ions can be prevented by purifying the glass raw material used, making the manufacturing method cleaner, etc., but solarization due to the glass structure is derived from the glass composition and is an essential problem, so it is prevented It is difficult. In general commercially available glass, for example, optical glass, plate glass, bottle glass, and the like, multi-component glass obtained by adding an alkali oxide or the like to SiO ₂ , which is the most important of the compounds constituting glass, is used. Such multi-component formation means that non-crosslinked oxygen is generated, and the above-mentioned problems caused by non-crosslinked oxygen cannot be avoided.

An object of the present invention is to solve the above-mentioned problems of the prior art, to reduce the generation of colored centers due to ultraviolet absorption, and to provide an optical material that can be used in the ultraviolet region (250 to 400 nm). I do. Another object of the present invention is to develop a glass composition capable of suppressing the generation of non-crosslinked oxygen in order to reduce the influence of ultraviolet irradiation depending on the glass structure, thereby providing a glass having a good ultraviolet transmittance. It is in.

[0009]

The above objects are preferably achieved by the following inventions. (1) S in mole%
iO ₂ is 3~65%, B ₂ O ₃ is 5 to 70%, LiF,
The total of one or two or more selected from NaF and KF is 15 to 50%, AlF ₃ is 0 to 20%, MgF ₂ ,
CaF ₂ , SrF ₂ and BaF ₂ are each 0-20.
%, YF ₃ 0 to 20% and LaF ₃ is UV resistant glass consisting of 0-20%. (2) 5% by mole of SiO ₂
60%, B ₂ O ₃ is 10 to 65%, LiF, one kind or the sum of two or more species selected from NaF and KF. 20 to
45%, further 0-15% AlF ₃ , MgF ₂ , CaF
₂ , SrF ₂ and BaF ₂ are each 0-10%, YF
₃ is 0-15% and LaF ₃ is 0-15%.

[0010] Non-crosslinked oxygen, which is considered as one of the causes of forming a colored center by absorbing ultraviolet light, is SiO ₂
It is formed when a glass network modifying compound such as an alkali oxide is added to a glass network constituting oxide such as. Of the halogens, only fluorine hardly forms a color center, and forms a stronger bond with boron or silicon than oxygen. For this reason, in a system containing fluorine, non-crosslinked oxygen that easily generates a color center is hardly generated, and the ultraviolet absorption edge shifts to a short wavelength, so that the glass is stable against ultraviolet light. For this reason, in the present invention, an alkali fluoride is used to reduce the amount of non-crosslinked oxygen produced.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. Table 1 shows the glass composition of the present invention. The composition is mol%.

[0012]

[Table 1]

[0013] SiO ₂ and B ₂ O ₃ are glass-forming oxides, and no glass can be obtained outside the above composition range. RF is an alkali fluoride, which is an important component in the present invention. L
Any one of iF, NaF, and KF is used, but if it is used alone or the total is less than 15%, the melting temperature becomes high and the fluorine component is lost due to volatilization and the like. If it exceeds 50%, vitrification becomes difficult. MgF ₂ , CaF ₂ , Sr
F ₂ and BaF ₂ are added to facilitate vitrification, but if each exceeds 20%, the effect is lost. AlF ₃ , YF ₃ , and LaF ₃ increase the chemical durability of glass, but if each exceeds 20%, vitrification becomes difficult. The glass of the present invention provides a transmission material that can be used in the ultraviolet region (wavelength: 250 to 400 nm), but is useful not only as a transmission material such as a window material but also as an optical fiber. In order to obtain a glass product requiring such thermal processing, a glass composition having sufficient thermal stability is required.

In order to meet the above-mentioned applications in the glass composition range of the present invention, a composition range more preferable than the glass composition shown in Table 1 is shown in Table 2. SiO ₂ and B ₂ O ₃ are glass-forming oxides, and it becomes difficult to obtain glass outside of these composition ranges. RF is an alkali fluoride, which is an important component in the present invention. Any one of LiF, NaF, and KF is used, but if it is used alone or the total is less than 20%, the melting temperature is slightly increased, and the fluorine component may be lost due to volatilization or the like. On the other hand, if it exceeds 45%, vitrification may be difficult. MgF ₂ , CaF ₂ , SrF
₂ and BaF ₂ are added to facilitate the vitrification, but if each exceeds 10%, the effect decreases.
AlF ₃ , YF ₃ , and LaF ₃ increase the chemical durability of glass, but if each exceeds 10%, vitrification becomes somewhat difficult.

In the multi-component glass composition of the present invention, by adopting the above-mentioned constitution, it is possible to prevent coloring from the visible region to the ultraviolet region and to prevent a decrease in transmittance. FIGS. 1 and 3 show the measurement results of the transmittance in the examples described later. It can be seen that there is almost no change in the transmittance after the irradiation with the ultraviolet rays as compared with the result of the comparative example in FIG.

In the present invention, any other glass component may be used regardless of fluoride or oxide as long as it is a component not accompanied by coloring or a component which is necessary for glass production and does not cause coloring by ultraviolet rays. . In order to prepare the glass composition for ultraviolet light resistance of the present invention, SiO ₂ , B ₂
O ₃ , LiF, NaF, KF, etc. are weighed according to the ratio of the target composition, mixed well, and then mixed in air at 1100-13.
Bake at a temperature of 00 ° C for 2-3 hours. The method for producing the composition of the present invention is not limited to the above method, and any method may be used as long as the desired composition is obtained. For example, since the raw materials may be mixed uniformly as long as the raw materials are uniformly mixed, a coprecipitation method, a wet method, a dry method, a sol-gel method, or any other method may be used.

[0017]

[Table 2]

[0018]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. (Embodiment 1) The embodiment Nos. Glass composition shown in No. 1, 5.4 mol% of SiO ₂ , 56.8 mol% of B ₂ O
_3. A glass raw material prepared in a predetermined weight ratio so as to have a KF of 37.8 mol% was melted in an electric furnace at 1200 ° C. for 3 hours. The container used at this time was a platinum crucible, and a platinum lid was applied during melting. The homogenized glass melt was poured into a mold to obtain a glass block. The obtained glass was polished to a thickness of 5 mm to obtain a sample for transmittance measurement.
Using a high-pressure mercury lamp on this glass sample, 2500 m
FIG. 1 shows the change in transmittance when irradiated with W / cm ² ultraviolet light (365 nm) for 100 hours.

The decrease in transmittance due to the irradiation of ultraviolet light does not appear on the measurement, and it can be seen that it is not affected at all. In addition, as a comparative example, the comparative example No. 5m thickness in one
When the transmittance was examined by similarly irradiating the oxide glass of m with ultraviolet rays, as shown in FIG. 2, there was a large change in the transmittance after irradiation. When such a decrease in transmittance occurs, it becomes difficult to use the optical component. On the other hand, the glass of Example 1 has no change in transmittance and can be sufficiently used even in an environment where ultraviolet rays are irradiated.

Examples 2 to 19 Glasses having the compositions shown in Tables 2 to 19 in Table 3 were produced in the same manner as in Example 1. These glass samples were irradiated with ultraviolet rays using a high-pressure mercury lamp as in Example 1, and the change in transmittance was measured. Among these, the transmittance of the glass of Example 11 is shown in FIG. As in Example 1, there was no change in transmittance before and after irradiation with ultraviolet light.

[0021]

[Table 3]

[0022]

[Table 4]

[0023]

[Table 5]

[0024]

[Table 6]

[0025]

According to the present invention, when an alkali metal fluoride is added to a SiO ₂ —B ₂ O ₃ system glass composition, it is possible to prevent a decrease in transmittance in the visible region to the ultraviolet region (wavelength 250 to 400 nm). And the UV coloring often seen in the multi-component glass is avoided.

[Brief description of the drawings]

FIG. Using a high-pressure mercury lamp on the 5 mm-thick UV resistant glass prepared in 1 above, 2500 mW /
7 is a graph showing a change in transmittance when irradiated with cm ² ultraviolet light (365 nm) for 100 hours.

FIG. In Example No. 1, a 5 mm thick oxide glass was used. 7 is a graph showing the results of examining the change in transmittance by irradiating with ultraviolet rays (24 hours) in the same manner as in FIG.

FIG. 11 is a graph showing the results of examining the change in transmittance of the glass of No. 11 by irradiating with ultraviolet rays (70 hours) in the same manner as in Example 1.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobuyoshi Baba 4-7-25 Harigaya, Urawa-shi, Saitama Prefecture Sumitomo Optical Glass Co., Ltd. (72) Inventor Koichi Tsuchiya 4-725-25 Harigaya, Urawa-shi, Saitama Stock (72) Inventor Hideo Hosono 2786-4, 212F, Shimotsuruma, Yamato City, Kanagawa Pref. EA01 EA02 EA03 EA04 EA05 EB01 EB02 EB03 EB04 EB05 EC01 EC02 EC03 EC04 EC05 ED01 ED02 ED03 ED04 EE01 EE02 EE03 EE04 EF01 EF02 EF03 F01 F01 F01 F01 F01 F01 F01 F01 F01 F01 F01 F01 F01 F01 F01 F01 F01 F01 F01 F01 F01 F01 F01 F01 GB01 GC01 GD01 GE02 HH01 HH03 HH05 HH07 HH09 HH11 HH13 HH15 HH17 HH20 JJ01 JJ03 JJ05 JJ07 JJ10 KK01 KK03 KK05 KK07 KK10 M M04 NN16 NN35

Claims (2)

[Claims] 1. The method according to claim 1, wherein the content of SiO ₂ is 3 to 65% in mole%, and the content of B ₂ O
₃ is 5 to 70%, the total of one or more selected from LiF, NaF and KF is 15 to 50%, and further AlF ₃
Is 0 to 20%, MgF ₂ , CaF ₂ , SrF ₂ and Ba
0 to 20% F _2, respectively, YF ₃ is 0 to 20%, La
UV resistant glass for F ₃ consists of 0-20%. Wherein SiO ₂ 5 to 60 percent by mol%, B ₂ O
₃ is 10-65%, the total of one or more selected from LiF, NaF and KF is 20-45%,
₃ is 0 to 15%, MgF ₂ , CaF ₂ , SrF ₂ and B
0% aF ₂ respectively, YF ₃ 0 to 15% and LaF ₃ is UV resistant glass consisting of 0-15%.