JPH0393646A - Ultraviolet ray transmitting glass - Google Patents

Abstract

PURPOSE:To obtain optical glass having a high transmittance within an ultraviolet region with hardly any deterioration in the transmittance due to irradiation with ultraviolet rays by melting glass with a limited component composition and containing specific amounts of especially Ba2P2O7, Al(PO3)3, BaF2 and AlF3 added thereto and forming the resultant melt. CONSTITUTION:Ultraviolet ray transmitting glass prepared by melting glass having the following composition. The aforementioned composition is 30-60wt.% Ba2P2O7, 15-20wt.% Al(PO3)3, 10-40wt.% BaF2, 5-15wt.% AlF3, 0-10wt.% MgF2, 0-10wt.% CaF2, 0-10wt.% SrF2, 0-5wt.% LiF, 0-5wt.% NaF, 0-5wt.% KF, 0-5wt.% ZnO, 0-5wt.% B2O3, 0-10wt.% NaPO3, <3ppm Fe, <3ppm Cr and <0.2wt.% additive, in which the total content of Fe, Cr and other transition metals is lower than 3ppm.

Description

[Detailed description of the invention] Industrial applications FIELD OF THE INVENTION The present invention relates to ultraviolet-transparent glass.

Prior Art and Issues Recently, optical glasses used in ultraviolet photography lenses (used for archaeology, police identification, etc.), ultraviolet erasing EFROM window glass, and optical systems using mercury lamps as a light source have become more and more popular. Transmits short wavelength light with higher efficiency,
In addition, there is a demand for an ultraviolet-transmitting glass that is excellent in its resistance to thermal irradiation.

In particular, reduction projection lenses used in steppers have a thick core and a large number of lenses.
It is required that the internal transmittance is >95% in the ultraviolet region and that the transmittance does not deteriorate due to ultraviolet irradiation (resistance to ultraviolet radiation).

As ultraviolet ray transmitting glass, see Japanese Patent Publication No. 54-36164: B20. -SiO, -La. A reduction technique by introducing O, -ZrO-divalent metal oxide composition and Snug is disclosed, and the transmittance λT80> 3 6 5 nap
(glass thickness 10 mm transmission wavelength) has been achieved; JP-A-55-3329: B. O. -Sing-La20B-Yb! 01 composite and SnO. A reduction technique by introducing the is disclosed.

Transmittance λT80> 3 6 5 nm (glass thickness 10+
am + transmission wavelength) has been achieved: Japanese Patent Publication No. 55-37500 and Japanese Patent Publication No. 56-40
Publication No. 094 discloses a P20 system composite, in which the transmittance λT80>3 6 5 no. (Glass thickness 1
0m+m transmission wavelength) has been achieved: JP-A-58-1
Publication No. 30136: P20, -Ta20, system composition is disclosed, transmittance λT80> 3 6 5 no+ (glass thickness 10II
II1 transmission wavelength) has been achieved: JP-A-60-46946: 820B-Sio! -AazO B
- A CaO-based compound has been disclosed, and F egos
<0. 0.3% by weight, and there is a description that a small amount of reducing agent may be included.

Thickness 3.6■■, transmittance of λ-25.7ros is approximately 69
%; JP-A-60-77144: B *O @1S io 1- N'a@O - A(
1!0 3 system composition is disclosed, F2.5-10
% by weight, and there is a description regarding reduction by SnO. The thickness is 1m+*, and the transmittance of λ-253.7n is 80-85%: JP-A-60-200842: S10. -B! 0 3 - AI2. O.
-R. 0 and F! A glass having a porous antireflection coating (surface treatment) consisting of 0.1' to 6% by weight of the composition is disclosed: JP-A-60-215547: Sin! -12.0. -B20. -CaO-HgO-B
aO and Fe20. A composition comprising <100 ppm is disclosed. A transmittance of -80% has been achieved; JP-A-6-1-20-1640: Sin. -B
．． O. -AI2.03-Na20-(CaO+HgO+
A composition of ZnO) -N10-CoO is disclosed: JP-A-62-27346: P20B-Sio! -Aff20 3
(7) A composition is disclosed: JP-A-62-65951: A composition consisting of P20s-B10sA (220s and Nip (15% by weight, Coo<15% by weight) is disclosed. JP-A-62-87433 discloses a composition consisting of SiO1-B10I-BaO and containing Fe and other transition metals <lppa+.

Transmittance λT80-300~320 (Glass thickness 10
JP-A-62-153142: Composition consisting of SiO1-B10I-AffzO@-Rho-RO and reducing agent carbon, tartaric acid, Si%AI
There is a description of using 2. Thickness l au++, λ-2
A transmittance of 75% at 53.7 nm has been achieved; JP-A-63-11544: P! O. A composition of -La20, -Li20 is disclosed; JP-A-63-265840: Si02-B10s P*Oa-Ti01-Nb10
@1(ZnO+PbO)1(LitO+Na*O+K*
0) is disclosed, and the transmittance λT80>4
20 has been achieved; JP-A-63-282-139: Sing-A2103-Boo. -Nano-(Li1
0+K20)-BaO-(As10,+Sb10.)-
A NiO-CoO composite has been disclosed; however, the method of the present invention is different from that of the present invention in achieving high transmittance in the light system and ultraviolet region, and the method for improving the transmittance is different from that of the present invention. is desired.

Also, J. Non-Cryst. Solids Kamidan (1989), p. 30, discloses a 3-part alkaline earth monometaphosphate glass using high-purity raw materials, but the system is different from the present invention and has a transmittance of λT50 (thickness). 10m
n+, wavelength at which transmittance is 50%) -195 to 300 nm.

Problems to be Solved by the Invention The present invention provides an optical glass that has high transmittance in the ultraviolet region and that does not (or has very little) deterioration in transmittance due to ultraviolet irradiation, more specifically, has an Abpe number νd of 66.
~80, the refractive index nd is 1.52 to 1.62, and the wavelength at which a transmittance of 80% or more is obtained at ioam thickness is 32
An object of the present invention is to provide an optical glass having a particle diameter of 0 nm or less.

Means for Solving the Problems In other words, the present invention is a highly ultraviolet transmitting glass with excellent solarization resistance produced by melting a glass having the following composition; BalP! of 30-60% by weight12
(POs) s l 5 to 20% by weight BaF.
10 = 40% by weight p,aFs
5 to 15% by weight MgF* 0 to
10% by weight CaF, 0-10% by weight S
rF2 o~10% by weight LiF
0~5wt% NaF 0~
5% by weight KF 0-5% by weight Zn
O 0-5% by weight B! OS
0~5wt% NaPOs
0-10% by weight Fe”◆
<3pp Cr"<3pp■ Reducing additives 0.2% by weight However, Fe,
The content of Cr and other transition metals is less than 3 ppm).

Generally, the main causes of absorption in the ultraviolet region in glass are (1) Many transition metal ions including Fes+ and Cr'' in the glass (2) Platinum that has begun to dissolve in the glass (if the melting crucible is platinum) (3) There is fundamental absorption in the ultraviolet region due to the glass structure.

On the other hand, the wavelength used for UV-transparent glass is approximately 2
It is around 50 to 440 nm, and the absorption due to the above (3) is thought to be on the shorter wavelength side than this wavelength.As long as the possibility of no absorption is used as the glass component, the absorption around 250 to 440 nm is This seems to be mainly due to (1) and (2). In particular, the absorption wavelength of Fe"+ or Cr" in (1) is 3gOn+m for Fe"+ and 350n for Cr●1, and the absorption coefficient is large, so even if a small amount is mixed, the transmittance will deteriorate. .

In the present invention, the valence state of iron and chromium is F.
In the case of a low atomic state of e'', Cr'', the absorption wavelength is 1050 nm for Fe'' and 430 nm for Cr''.

Furthermore, the glass produced according to the present invention also has good solarization resistance.

BaP30. has a content of 30% by weight (hereinafter referred to as wt%)
If the amount is less than 60 wt%, devitrification occurs, and if it is more than 60 wt%, glass cannot be obtained.

Aff(POs)s is a component that stabilizes the glass, so if it is less than 15wt%, it will not have this effect, and 2Qwt
If it exceeds %, phase separation will occur.

BaF is a component that makes the glass a high refractive index and stabilizes it, but if it is less than 10 wt%, this effect is poor <40
If it exceeds wt%, the glass will devitrify.

AQFs is a component that stabilizes the glass, and if it is less than 5wt%, this effect will not occur, but if it is more than 15wt%, phase separation will occur.

MgF2CaF2SrF1, LiF, NaF, and KF play a role in adjusting the viscosity of the glass, but when the content exceeds 10, 10, 10, 5, 5, and 5 wt%, respectively, the liquidus temperature increases.

ZnOs B! OS and NaPO increase the refractive index of glass by 5, 5, and 10%, respectively.
If the amount is higher than that, the glass becomes devitrified.

Reducing additives include Si, C, etc., and these substances reduce impurities (iron, chromium, etc.) mixed in raw materials and processes (crucibles) to a low valence state, and reduce transmission in the ultraviolet region. It works to improve the rate. Their usage is 0.2
vt% and 0.5% for Si. l w
Amounts up to t% are preferred. 0. reducing substances. :)wL%
If these substances are used, these substances will remain in the glass as unmelted substances, and conversely cause deterioration of ultraviolet transmittance.

Fe3°, Cr" significantly deteriorates the transmittance in the ultraviolet region, and its absorption number is large, so Fe and C
The content of r is 3 ppta or less.

Fe%Cr and other transition metals (e.g. Mn.Ni
, Co), etc., the total amount thereof should be 3 ppm or less from the viewpoint of deterioration of transmittance in the ultraviolet region.

The production of optical glass involves melting glass raw materials (powder) once,
The melt obtained by mixing may be poured into a desired mold and cooled to solidify. Another method is to crudely melt the glass raw material (powder) to once produce karefth (glass particles), and then finish melt it in order to match the optical constants.

In the case of the former manufacturing method, a crucible made of highly pure ceramics is used. In the case of the latter manufacturing method, it is also preferable to use a high-purity ceramic crucible for the rough melting, and to use a high-purity platinum crucible in a neutral or reducing atmosphere for the final melting.

The reason why high-purity ceramics are used in this way is that since the present invention uses a reducing agent, it is difficult to use a platinum crucible for rough melting.

High-purity ceramic crucibles are made of materials such as quartz, alumina, and carbon, and impurities in these materials
e<3 1)pL Cr<3 1)I) L and other transition metals (for example, (MnsNi, Co) etc. in a total amount of 3 pI)II are used. Use of such a crucible is effective in preventing the contamination of Fe, Cr, etc. into the glass assembly.

As the high-purity platinum-gold crucible, it is preferable to use one containing the same impurities and amounts as the above-mentioned high-purity ceramic crucible. The reason for using such high purity platinum is the same as the reason for using a high purity ceramic crucible.

Although it is possible to melt the glass lens under a normal air atmosphere, it is useful to perform the melting under a neutral or reducing atmosphere.

Melting in a neutral atmosphere results in Fe in a low valence state.”
, Cr" from becoming highly atomized (Fe", Cr": absorption in the ultraviolet region). Such an atmosphere can be created by using an inert gas such as Ar or N2. It is.

Melting under a reducing atmosphere produces a high valence state (Fe”Cr
'+, etc.) to a low valence state (Fe", Cr"), as well as Fe" in a low valence state,
It is also effective in preventing Cr3+ from becoming highly atomized (Fe"°, Cr"). Such an atmosphere can be obtained by mixing about 5% by volume of a reducing gas such as H2 or CO with an inert gas such as N2A.

It has been found that if the ultraviolet-transmitting glass of the present invention is produced throughout the entire process in a neutral or reducing atmosphere, the addition of a reducing agent is not necessarily necessary, and even in that case, the object of the present invention can be achieved. t;.

Herein, the present invention provides a highly UV-transparent glass with excellent solarization resistance prepared by melting a glass having the following composition: Ba*P*Ot 30 to 60% by weight A(2(P)
Os) s l 5-20% by weight BaFx
10-40% by weight AI2Fs 5-15% by weight MgF, 0-10% by weight CaF1
0”10wt%SrF=
o-lo wt% LiF 0-5 wt% NaF 0-5 wt% KF
0 to 5% by weight ZnO
0 to 5% by weight B20. 0-5% by weight NaP03 0-10% by weight Fe
<3 ppmCr
<3 ppm, but the content of Fe%Cr and other transition metals is less than 3 ppm.

Non-oxidizing atmosphere means the above-mentioned neutral atmosphere or reducing atmosphere.

Using only the reduction method produces more Fe than not using it.”
It is possible to actively shift the redox equilibrium of -+Fe", Cr"-ecr3+ toward the reduced state Fe"+, Crs", and relatively the total amount of iron and total chromium mixed in the glass The ratio of Fe'' and Cr''+ can be increased.

For this purpose, it is preferable to use high-purity raw materials with as little impurities (iron, chromium, etc.) as possible, and to use a glass melting crucible such as the above-mentioned high-purity ceramic crucible or self-made metal crucible.

The present invention will be explained below with reference to Examples.

EXAMPLE An ultraviolet transmitting glass having excellent solarization resistance according to the present invention was prepared in the following manner under the assembly conditions and conditions shown in Tables 1 and 2.

Note that the total content of Fe, Cr, and other transition metals in the glass raw material was 3 ppm or less.

(1) One-time melting Numbers 1 to 13 at the top of Table 1 indicate examples in which glass was manufactured by one-time melting.

A glass composition shown in Table 1 was produced by melting 100 g of glass in a quartz crucible at a temperature of 1000 to 150''0, stirring, pouring into a preheated mold, shaping, and slow cooling.

(2) Twice melting In Table 1, the numbers 1-R-13-R at the top indicate examples in which glass was produced by melting twice.

The second melting used a non-oxidizing atmosphere during melting. The glass is made by melting the glass of the same composition as used in (1) above in a platinum crucible at a temperature of 950 to 1100 °C in a non-oxidizing atmosphere, stirring it, pouring it into a preheated mold, shaping it, and slowly cooling it. Manufactured. (3) Atmosphere In Table 2, the top number l-E-13-E indicates an example in which a non-oxidizing atmosphere was used without using a reducing agent. 100 g of the assembled glass shown in Table 2 was melted in a platinum, quartz, alumina, and carbon crucible at a temperature of 1000-1250°C in a non-oxidizing atmosphere, and after stirring,
It was manufactured by pouring it into a preheated mold, shaping it, and slowly cooling it.

As a comparative example, R-1 is used as a comparative example of l-H,
R-3 is shown in Table 2 as a comparative example.

As each raw material in the table, appropriate compounds such as phosphates, fluorides, and oxides were used. In addition, in each table, λT80 is based on the Japan Optical Glass Industry Association standards, and the thickness is 1
A spectral transmittance curve was obtained for a sample whose opposite surfaces were mirror-polished in parallel at 0 W, and the wavelength at which the transmittance was 80% was shown. λ゛T80 is based on the same standard.The sample is irradiated with a 10OW high-pressure mercury lamp at a distance of 30wam for 3 hours, and after 20 minutes, λT80 is applied.
It was measured in the same manner as 80.

In the atmosphere column, N2 is nitrogen, Ar is argon, H2 is 9
5% nitrogen + 5% hydrogen, CO represents 95% nitrogen + 5% carbon monoxide, respectively.

Also, the value of (nd − 1) is Cnd − 1 ) *
Represents a value of 1 0 0 0 0.

(Hereafter, margin) Effect of the invention

Claims (1)

[Claims] 1. High ultraviolet transmittance glass with excellent solarization resistance produced by melting glass with the following composition: Ba_2P_2O
_730-60 weight% Al(PO_3)_315-20 weight% BaF_210-40 weight% AlF_35-15 weight% MgF_20-10 weight% CaF_20-10 weight% SrF_20-10 weight% LiF0-5 weight% NaF0-5 weight% KF0 -5% by weight ZnO 0-5% by weight B_2O_30-5% by weight NaPO_30-10% by weight Fe<3ppm Cr<3ppm Reducing additives<0.2% by weight However, the content of Fe, Cr and other transition metals is 3
Less than ppm. 2. The reducing additive is Si, and the amount added is Si<0
．． 2. The glass of claim 1, wherein the amount is 1% by weight. 3. The reducing additive is C, and the amount added is C<0.2
% by weight of the glass according to claim 1. 4. The glass according to claims 1 to 3, wherein the crucible used for melting is high-purity quartz, alumina, platinum, and carbon. 5. The amount of impurities in the crucible during melting is Fe<3ppm
, Cr<3ppm, and content of other transition metals<3
The crucible according to claim 4, wherein the amount is ppm. 6. The glass according to any one of claims 1 to 5, wherein the melting comprises rough melting and remelting, and the remelting is performed in a high purity platinum crucible. 7. The crucible according to claim 6, wherein the high purity platinum has a purity of Fe<3ppm, Cr<3ppm and content of other transition metals<3ppm. 8. Remelting in a neutral atmosphere of Ar and N_2 or N
Glass according to claims 1 to 6, characterized in that the process is carried out in a reducing atmosphere of _2+5% H_2 and N_2+5% CO. 9. High UV transmittance glass with excellent solarization resistance made by melting glass with the following composition; Ba_1PO_3
30-60% by weight Al(PO_3)_315-20% by weight BaF_210-40% by weight AlF_35-15% by weight MgF_20-10% by weight CaF_20-10% by weight SrF_20-10% by weight LiF0-5% by weight NaF0-5% by weight KF0 ~5 wt% ZnO0~5 wt% B_2O_30~5 wt% NaPO_30~10 wt% Fe<3ppm However, the content of Fe, Cr and other transition metals is 3
Less than ppm. 10. The glass according to claim 9, wherein the non-oxidizing atmosphere is a neutral atmosphere of Ar and N_2. 11. The non-oxidizing atmosphere is N_2 + 5% H2, and N
The glass according to claim 9, wherein the reducing atmosphere is _2+5% CO. 12. The crucible used for melting is made of high purity quartz, alumina,
The glass according to claim 9, which is platinum and carbon. 13. The amount of impurities in the crucible during melting is Fe<3pp
m, Cr<3ppm, and content of other transition metals<
13. The crucible according to claim 12, wherein the concentration is 3 ppm.