JPH0656467A - Ultraviolet light absorbing glass - Google Patents

Abstract

PURPOSE:To obtain an ultraviolet light absorbing glass being colorless and transparent because of high light transmittance in a visible range, capable of efficiently absorbing ultraviolet rays of <=320nm wavelength harmful to human body. CONSTITUTION:Ultraviolet light absorbing glass has a composition comprising 65-80wt.% SiO2, 5-20wt.% B2O3, 2-8wt.% Al2O3, 1-5wt.% RO (RO is one or more selected from MgO, CaO, BaO, SrO and ZrO), 4-8wt.% R20 (R20 is one or more selected from Na2O, K2O and Li2O), 0.3-4wt.% CeO2, 0.01-0.2wt.% Fe2O3, 0.0005-<0.005 V2O5 and 0-2wt.% TiO2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet absorbing glass, and more particularly to an ultraviolet absorbing glass used for a light source envelope for illumination such as a bulb for a mercury lamp.

[0002]

2. Description of the Related Art Glass used for lighting light source enclosures such as bulbs for mercury lamps has characteristics such as chemical durability.
It is very important to have UV absorptivity. That is,
It is well known that ultraviolet rays having a wavelength of 320 nm or less are harmful to the human body, and in particular, when they are irradiated with ultraviolet rays having a wavelength shorter than 300 nm, they may cause dermatitis or cause skin cancer. If you look straight ahead,
It has a significant adverse effect on the tissues of the eye. Further, not only the human body but also articles such as exhibits are irradiated with ultraviolet rays, so that the coloring of the articles is faded.

It has been conventionally known to add Fe ₂ O ₃ , TiO ₂ or CeO ₂ in order to impart ultraviolet absorption to glass. However, when these additive components are used, it is difficult to impart sufficient ultraviolet absorption while maintaining a high light transmittance in the visible range (400 to 700 nm). For example, Fe ₂ O ₃ is a component that can be used inexpensively as a raw material, but when it is added in an amount sufficient to absorb light in the ultraviolet region, which is harmful to the human body, the glass is colored blue green and used as a bulb for mercury lamps. In this case, the initial luminous flux of illumination is significantly reduced, which is not preferable. Further, when TiO ₂ is used together with Fe ₂ O ₃ and CeO _2, it can efficiently absorb light in the ultraviolet region, but since it is easily colored yellow due to the action of the glass melting atmosphere, it is similar to Fe ₂ O _3. It is not possible to add a sufficient amount. On the other hand, when CeO ₂ is used, it needs to be added in a large amount, but the raw material price is expensive, which greatly increases the raw material cost of glass. As ₂ O as a fining agent for the glass containing CeO _{2.
When 3} is added, solarization is likely to occur, the glass is colored over the entire visible range, and the transmittance is lowered, which is not preferable.

Under these circumstances, it has been proposed to use V ₂ O ₅ as a component that imparts ultraviolet absorption to glass. For example, Japanese Examined Patent Publication No. 61-24344 discloses an ultraviolet absorbing glass obtained by adding 0.002 to 0.5% of V ₂ O ₅ to borosilicate glass.

[0005]

However, even in the ultraviolet absorbing glass of Japanese Patent Publication No. 61-24344, there is a problem that the glass is colored yellow green when it is attempted to have sufficient ultraviolet absorbing property. There is.

An object of the present invention is that it is colorless and transparent because of its high light transmittance in the visible range, and it has a wavelength 320 which is harmful to the human body.
An object of the present invention is to provide an ultraviolet absorbing glass capable of efficiently absorbing ultraviolet rays having a wavelength of nm or less.

[0007]

As a result of various studies, the inventors of the present invention have suppressed the content of V ₂ O ₅ to less than 0.005%, and have a specific amount of CeO ₂ , Fe ₂ O ₃ It was found that a glass having an efficient ultraviolet absorption can be obtained by coexisting with, and is proposed as the present invention.

That is, the ultraviolet absorbing glass of the present invention has a weight percentage of SiO ₂ 65 to 80% and B ₂ O ₃ 5 to 20%.
%, Al ₂ O ₃ 2-8%, RO 1-5% (however, RO
Is one or more selected from the group consisting of MgO, CaO, BaO, SrO and ZnO), R ₂ O 4 to 8% (provided R ₂ O is Na ₂ O, K ₂ O or Li ₂ O). 2 or more kinds selected from the group), CeO ₂ 0.3 to 4%, Fe ₂ O ₃
0.01~0.2%, V ₂ O ₅ 0.0005~0.00
It is characterized by having a composition of less than 5% and TiO ₂ 0 to 2%.

[0009]

The UV-absorbing glass of the present invention comprises 0.3% to 4% CeO ₂ and 0.01 to 0.2% in borosilicate glass.
Fe ₂ O ₃ and 0.0005-0.005% V ₂ O ₅
By coexisting, the light transmittance at a wavelength of 400 nm is 70% or more at a thickness of 1 mm, the light transmittance at a wavelength of 350 nm is at most 30% at a thickness of 1 mm, and the absorption edge of light in the ultraviolet region is 320 at a thickness of 1 mm
It is on the longer wavelength side than nm. Therefore, it is colorless and transparent and can efficiently absorb ultraviolet rays.

The reason why the composition range of the ultraviolet absorbing glass of the present invention is limited as described above will be described below.

SiO ₂ is a glass former and its content is 65 to 80%. If the SiO ₂ content is less than 65%, the chemical durability will deteriorate, and if it is more than 80%, it will be difficult to homogenize the melt, and the product will have spots, bubbles and striae.
Yield decreases.

B ₂ O ₃ acts as a melting accelerator,
It is also a useful component for improving the chemical durability of glass, and its content is 5 to 20%. B ₂ O ₃ is 5
If it is less than 20%, the meltability deteriorates, and if it exceeds 20%, the phase separation tendency increases and the glass becomes unstable, and the chemical durability remarkably deteriorates.

Al ₂ O ₃ is an important component for improving the chemical durability of glass and improving the devitrification, and the content thereof is 2 to 8%. If the content of Al ₂ O ₃ is less than 2%, the glass tends to devitrify and the chemical durability decreases. On the other hand, when it is more than 8%, the viscosity of the glass becomes high and the melting becomes difficult, so that the glass becomes inhomogeneous.

RO has the effect of improving the devitrification tendency of the glass and also improving the chemical durability, and MgO, CaO,
One or two or more selected from the group consisting of BaO, SrO, and ZnO is contained in a total amount of 1 to 5%. If RO is less than 1%, the glass tends to devitrify and the chemical durability is deteriorated, but if it is more than 5%, devitrification is likely to occur, and spots and striae are generated in the product.

R ₂ O is a component for improving the melting property of glass, and contains 4 to 8% in total of two or more kinds selected from the group of Na ₂ O, K ₂ O and Li ₂ O. If the amount is less than 4%, the effect is scarce, and if it is more than 8%, the chemical durability of the glass is deteriorated, and the coefficient of thermal expansion is increased to lower the heat resistance. It should be noted that these alkaline components
The use of more than one species is to prevent deterioration of chemical durability due to the mixed alkali effect.

In addition to the above composition, the ultraviolet absorbing glass of the present invention further comprises CeO ₂ , Fe ₂ O ₃ and V ₂ O _5.
Is contained as an essential component.

CeO ₂ is an important component for imparting ultraviolet absorption to the glass, and also functions as a fining agent, the content of which is 0.3 to 4%, preferably 0.5 to 3
%. If CeO ₂ is less than 0.3%, the above effect cannot be obtained. On the other hand, when it is more than 4%, the Ce colloid is precipitated in the glass and is easily devitrified, and the transmittance in the visible region of 400 to 700 nm is significantly reduced.
Moreover, the raw material cost of glass becomes high.

Fe ₂ O ₃ is a component necessary for imparting ultraviolet absorption to the glass and moving the light absorption edge to the longer wavelength side, and the content thereof is 0.01 to 0.2%. . If Fe ₂ O ₃ is less than 0.01%, the effect cannot be obtained, and if it is more than 0.2%, the transmittance in the visible region is lowered.

When V ₂ O ₅ coexists with CeO ₂ , it has the effect of further enhancing the ultraviolet absorption even with a small content, and also has the effect of moving the light absorption edge in the ultraviolet region to the long wavelength side. Yes, the addition amount is 0.0005 to 0.0
05% (but not including 0.005%), preferably 0.0005 to 0.004%. V ₂ O ₅ is 0.0
If it is less than 005%, the ultraviolet absorption effect is insufficient,
On the other hand, when it is 0.005% or more, the transmittance in the visible region, especially 4
It is not preferable because the transmittance at 00 nm is deteriorated and it is colored in greenish green, and the initial luminous flux is lowered in lighting applications such as bulbs for mercury lamps.

TiO _{2 is} also a component that imparts ultraviolet absorption to glass, and it is possible to add up to 2%.
If it exceeds%, the absorption band of glass extends to the visible range, 40
Since the transmittance at 0 nm is remarkably reduced, it becomes unsuitable for illumination applications such as bulbs for mercury lamps.

Next, a method of manufacturing a light source envelope for illumination such as a bulb for a mercury lamp using the ultraviolet absorbing glass of the present invention will be described.

First, raw materials are prepared so as to have the above composition, and a batch is prepared. As the raw material, for example, purified silica powder, anhydrous borax, boric acid, aluminum oxide, magnesium oxide, calcium carbonate, barium carbonate, soda ash,
Potassium carbonate, cerium oxide or cerium hydroxide, ferric oxide, vanadium pentoxide, etc. are used.

Next, the batch was put into a glass melting furnace and
It melts at 400-1550 ° C. In addition, in order to prevent the coloring of the glass and enhance the refining action, it is desirable to make the melting atmosphere oxidizing. As a method of making the melting atmosphere oxidizable, for example, a part of soda ash may be replaced with sodium nitrate to prepare a raw material batch, and a small amount of Sb ₂ O ₃ or the like may be added to the raw material.

After that, the obtained molten glass is blow-molded by hand or mechanically blow-molded to manufacture a light source envelope for illumination such as a bulb for a mercury lamp having a desired shape.

[0025]

EXAMPLES The ultraviolet absorbing glass of the present invention will be described below based on examples. Table 1 shows examples of the present invention (Sample N
o. 1 to 7) and Table 2 show comparative examples (Sample Nos. 8 and 9), respectively.

[0026]

[Table 1]

[0027]

[Table 2]

Each sample was prepared as follows. First, purified silica powder, anhydrous borax, aluminum oxide, magnesium oxide, calcium carbonate, barium carbonate, strontium carbonate, zinc oxide, soda ash, sodium nitrate, potassium carbonate, cerium oxide, ferric oxide, vanadium pentoxide,
Titanium oxide was mixed so as to have the composition shown in the table to prepare a raw material batch. In order to make the melting atmosphere oxidizable, the content of sodium nitrate was adjusted to 5% by weight of the total raw materials. Then, the batch was put into a platinum pot and melted in an electric furnace at 1400 to 1550 ° C. for 5 hours. Then, the molten glass was poured into a carbon mold, held at 560 ° C. for 1 hour, and then gradually cooled to obtain a sample.

Each sample obtained in this manner was treated with 20 × 2.
Cut out to 0 × 1 mm, optically polished, absorption edge wavelength of light in the ultraviolet region, wavelength 350 nm, 400 nm, 55
The light transmittance at 0 nm and 700 nm was measured by a spectrophotometer. In addition, each sample was crushed and classified in an alumina mortar, and J
Based on the IS-R-3502 method, the amount of alkali elution was determined by atomic absorption spectrometry.

As is apparent from Table 1, N which is the embodiment
o. Each of the samples 1 to 7 has an absorption edge wavelength in the ultraviolet region of 325 to 3
Light transmittance of 30 at 40 nm and wavelength of 350 nm
% Or less, and has excellent ultraviolet absorption. Moreover, 40
0nm is 71.4 to 89.9%, 550nm is 88.6.
.About.92.2% and 700 nm is 90.8 to 92.9%, and the transmittance in the visible region is high. The amount of alkali elution is 0.03 to 0.06 mg, which shows that the chemical durability is excellent.

On the other hand, as is clear from Table 2, the sample No. which is a comparative example. Sample No. 8 had a high transmittance in the visible range and had an alkali elution amount similar to that of the example, but had an absorption edge wavelength in the ultraviolet range of 230 nm on the short wavelength side and had an effect of absorbing ultraviolet rays harmful to the human body. Almost never. On the other hand, sample No. 9
Has a good absorption edge wavelength in the ultraviolet region of 350 nm,
Since the light transmittance at 400 nm is as low as 40%, it is unsuitable for use in a bulb for mercury lamps, etc., because the initial luminous flux becomes low.

Sample No. Regarding 1 to 7, JIS-
According to B7753, a 24 hour ultraviolet irradiation test was carried out using a sunshine carbon arc lamp type weather resistance tester, and the difference in transmittance before and after irradiation was measured. No decrease in transmittance was observed in any of the samples. This indicates that the ultraviolet absorbing glass of the present invention is also excellent in solarization resistance.

[0033]

As described above, the ultraviolet absorbing glass of the present invention completely absorbs ultraviolet rays of 320 nm or shorter, which are harmful to the human body, and has a high light transmittance in the visible region. Moreover, since it is also excellent in solarization resistance and chemical durability, it is suitable as a bulb for mercury lamps used for outdoor lighting and fishing lights that are easily affected by seawater.

Claims (1)

[Claims] 1. SiO ₂ 65-80% by weight percentage, B
₂ O ₃ 5-20%, Al ₂ O ₃ 2-8%, RO 1-5
% (However, RO is MgO, CaO, BaO, SrO,
One or more selected from the group of ZnO), R ₂ O
4-8% (however, R ₂ O is Na ₂ O, K ₂ O, Li ₂
2 or more kinds selected from the group of O), CeO ₂ 0.3 to 4
%, Fe ₂ O ₃ 0.01 to 0.2%, V ₂ O ₅ 0.00
An ultraviolet-absorbing glass having a composition of 05 to less than 0.005% and 0 to 2% of TiO ₂ .