JPH0812369A - Glass for hid lamp - Google Patents

Abstract

PURPOSE:To obtain a glass for uncolored high intensity discharge lamp excellent in heat resistance and ultraviolet cut-off property by using a borosilicate glass as a base, blending a prescribed quantity of V2O5, Fe2O3, CeO2, TiO2 or the like to specify spectral transmission factor. CONSTITUTION:This glass for HID(high intensity discharge) lamp is produced by using the borosilicate glass as the base glass, blending 0.03-3wt.% at least 2 kinds of V2O5, Fe2O3, CeO2 and TiO2 (where each of 0.5% V2O5, 0.3% Fe2O3, 2% CeO2 and 2% TiO2 is the upper limit) to control spectral transmission factor of 320nm wave length at 4mm thickness to <=5%. The composition composed of 55-85% SiO2, 0.5-8% Al2O3, 2-8% Na2O+K2+Li2O, 0.01-10% CaO+MgO+ BaO+ZnO and 5-20% B2O3 is exemplified as the preferable concrete composition of the glass. The glass is suitably used for a front glass of the light source such as HID lamp accompanying the radiation of harmful ultraviolet ray.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a glass suitable for a front glass of a light source with ultraviolet radiation such as an ID (high intensity discharge) lamp.

[0002]

2. Description of the Related Art HID lamps have mainly been used as outdoor lighting, facility lighting for sports facilities, factories and the like. However, in recent years, the features that HID lamps have such as high brightness with a low power consumption and long life have been noticed, and the miniaturization of the lamps itself has progressed. It is considered to be used for applications such as lighting equipment and automobile headlights.

Conventionally, incandescent light bulbs such as halogen lamps have been used for these lighting applications, and the front glass of a light bulb with a reflecting mirror and the headlight lens of an automobile have high heat resistance because of high temperature of the light source. Borosilicate glass, which has excellent translucency, is used.

It is known that HID lamps emit a large amount of ultraviolet rays simultaneously with visible rays. Therefore, in order to absorb the ultraviolet rays in the envelope bulb of the lamp, which has conventionally been a source of the ultraviolet rays, for example, Japanese Patent Publication No. 61-2
Glass obtained by adding V ₂ O ₅ as an ultraviolet absorber to borosilicate glass as described in JP-A No. 4344 and JP-A No. 6-72738 has been used.

[0005]

As described above, with the miniaturization of HID lamps, the envelope bulb of the lamp is no longer used, and it has become difficult to remove ultraviolet rays by the envelope bulb. The arc tube of the lamp itself is made of quartz glass and transmits ultraviolet rays. Conventionally, borosilicate glass used for a front glass of a light bulb with a reflecting mirror or a headlight lens of an automobile is generally colorless and transparent and transmits ultraviolet rays, and cannot be used in front of such an HID lamp.

The new uses of the HID lamp as described above are closer to the living environment of human beings than ever before, and particularly in the use where the human body is directly exposed, it is necessary to remove the ultraviolet rays from the light source. Further, there is a problem of discoloration and deterioration due to ultraviolet rays depending on the object to be irradiated, so it is necessary to remove the ultraviolet rays from the light source.

From such a background, Japanese Patent Laid-Open No. 6-7273
The glass described in Japanese Patent No. 8 was developed, but this glass is intended to cut near-ultraviolet rays and has an ultraviolet absorption edge on the long wavelength side of 340 nm or more. Therefore, this glass contains V ₂ O ₅ in a relatively large amount of 0.03 to 0.9% by weight, and allows the coloring of the glass by V ₂ O ₅ to some extent.

On the other hand, however, there is an idea to utilize the action of near ultraviolet rays. For example, ultraviolet rays have the effect of exciting fluorescence for certain substances, and this effect of fibers and fluorescent whitening agents contained in them is used to turn near-ultraviolet light sources into street lights and automobile headlights. When used, it enhances the visibility of pedestrians and two-wheeled vehicles due to fluorescence from clothing, and is used for display illumination to make products and displays look vivid. The glass described in JP-A-6-72738 cannot be used for such purpose because it does not transmit near-ultraviolet rays.
In addition, it cannot be used for applications in which coloring of glass that is visually confirmed is not preferred.

The glass described in the above Japanese Patent Publication No. 61-24344 has the purpose of blocking harmful ultraviolet rays, and V ₂ O
₅ in the range of 0.005 to 0.5% by weight. This glass is basically colorless and transparent, but it is considered that this glass has a wall thickness of about 1 mm formed as a blown product. According to a test conducted by the present inventor, as described in JP-A-6-72738, in this type of glass, absorption appears even in the visible region as the V ₂ O ₅ content increases,
When it exceeds 0.05%, coloring can be confirmed in the thick portion of the product, and when it is about 0.5%, coloring can be seen from the direction perpendicular to the plate surface having a thickness of 4 mm. Therefore, it is necessary to reduce the V ₂ O ₅ content in thick-walled products that dislike coloring, but in these glasses that absorb UV light due to the addition of V ₂ O ₅ , the UV absorption capacity also decreases at the same time. This may result in failure to achieve the intended purpose.

The present invention has been made in view of the above circumstances, and provides a glass capable of reliably blocking harmful ultraviolet rays without being colored even when formed into a relatively thick wall. With the goal. Another object of the present invention is to provide a glass which has excellent heat resistance and is suitable for an HID lamp that can be arranged near a light source that becomes hot.

[0011]

In order to achieve the above object, the present invention uses a borosilicate glass as a basic glass and combines a plurality of ultraviolet absorbing components to be added to the basic glass. That is, the present invention uses borosilicate glass as a basic glass, and contains 0.03 to 3% by mass of V ₂ O ₅ , Fe ₂ O ₃ , CeO ₂ , and TiO ₂ (provided that V
₂ O ₅ 0.5%, Fe ₂ O ₃ 0.3%, CeO ₂ 2%,
TiO _{2 (up to} 2% is the upper limit), and the glass for HID lamps has a spectral transmittance at a thickness of 4 mm of 5% or less at 320 nm.

Further, the basic glass is made of SiO 2 in mass%.
₂ 55-85%, Al ₂ O ₃ 0.5-8%, Na ₂ O +
K ₂ O + Li ₂ O 2-8%, CaO + MgO + BaO
+ ZnO 0.01 to 10%, B ₂ O ₃ 5 to 20%.

Further, the spectral transmittance at a thickness of 4 mm is 3
The glass has a content of 1% or less at 00 nm and is used by being arranged in front of a projection type HID lamp.

[0014]

In the present invention, since borosilicate glass is used as the basic glass, it has excellent heat resistance and chemical durability. Therefore, even if the front glass is overheated due to the heat generated by the light source and rapidly cooled by rainwater or the like, it is not damaged, and the weathering does not impair the translucency. In the present invention, V ₂ O ₅ 0.5%,
Fe ₂ O ₃ 0.2%, CeO ₂ 2%, and TiO ₂ 2% are the upper limits, and at least two of these are 0.03 to 3
It was contained by mass%. As a result, the amount of each ultraviolet absorber added alone can be suppressed to a small level, coloring of the glass is less likely to appear, and the necessary ultraviolet absorption characteristics can be secured.

V ₂ O ₅ , Fe ₂ O ₃ , CeO ₂ , TiO
₂ Each upper limit value is not preferable because if it is added in excess of that value, coloring becomes remarkable. Preferably,
V ₂ O ₅ is 0.2% or less, Fe ₂ O ₃ is 0.2% or less,
More preferably 0.1% or less, CeO ₂ is 1% or less, T
iO ₂ is 1% or less. Further, if the total amount of at least two of them is less than 0.03%, sufficient absorption of ultraviolet rays cannot be obtained, and if it exceeds 3%, coloring of the glass appears, which is not preferable. It is preferably 0.05 to 2.3%.

Of these components, CeO ₂ or TiO ₂ has the function of preventing coloring of the glass due to ultraviolet irradiation when added to the glass. Therefore, even if it is arranged in the vicinity of the HID lamp, which is a strong ultraviolet ray source, the addition of these prevents the glass from being colored due to the lighting of the lamp and can maintain an excellent transmission state for a long period of time.

[0017] The harmful ultraviolet rays that damage the cornea or conjunctiva of the human body specified by JIS-Z-8812 range from 200 to 200.
It is 315 nm, and if the spectral transmittance at a glass thickness of 4 mm is 5% or less at 320 nm, it can be said that there is almost no problem. Further, if it is 1% or less at 300 nm, it is more reliable.

Next, the action of each component constituting the composition preferable as the basic glass of the present invention and the reason why the composition range is limited as described above will be explained.

SiO ₂ is a main component for forming a glass network, but if it is less than 55%, the network is weak and the water resistance deteriorates, and if it exceeds 85%, the melting property deteriorates, which is not preferable. It is preferably 68 to 82%.

Al ₂ O ₃ is effective in improving the chemical durability, but if it is less than 0.5%, the effect cannot be obtained, and if it exceeds 8%, striae are likely to occur. Preferably 1 to 4%
Is.

Na ₂ O, K ₂ O and Li ₂ O lower the viscosity of the glass and accelerate the melting. If the total amount of these is less than 2%, the effect is not exerted, and if it exceeds 8%, the chemical durability is increased. Cause deterioration of. It is preferably 2 to 6%.

CaO, MgO, BaO and ZnO improve the meltability and the chemical durability, but the total amount is 0.0
If it is less than 1%, the effect cannot be obtained, and if it exceeds 10%, the devitrification tendency is increased and crystals are likely to occur.

B ₂ O ₃ has the effect of improving the meltability, but if it is less than 5%, it has no effect of improving the meltability, and if it exceeds 20%, the chemical durability deteriorates. Preferably 7 to 17%
Is.

[0024]

EXAMPLES Examples of the present invention will be described below. Examples of the present invention are shown in Table 1. In Table 1, samples No.1 to No.5
Shows an example of the present invention, No. 6 and No. 7 are comparative examples,
No.6 is borosilicate glass that does not contain UV absorber, No.7 is V
The ₂ O ₅ 0 content is obtained by increasing. Further, the composition in the table is shown by mass%.

In each of these glasses, raw materials were prepared so as to obtain a predetermined component composition, and each glass was housed in a platinum crucible, melted at a temperature of 1500 to 1600 ° C., sufficiently stirred and clarified, and then a mold was prepared. The sample was cast into the inside, slowly cooled, cut and polished, and formed into a flat plate having a thickness of 4 mm to obtain a sample for measuring transmittance.

The spectral transmittance of these samples was measured with a spectrophotometer. Table 1 shows the transmittances at 320 nm and 300 nm.

[0027]

[Table 1]

It can be seen from Table 1 that each of the glasses of the examples according to the present invention absorbs ultraviolet rays to the extent that they have almost no effect. The sample of Comparative Example No. 7 is 320n
The transmittance is 0 at both wavelengths of m and 300 nm.
However, since this glass has an ultraviolet absorption edge of 360 nm, it cannot be used for applications using near ultraviolet rays.

In the glass of the example, coloring was not observed when viewed from the direction perpendicular to the plate surface with a white background and a thickness of 4 mm, whereas the sample of No. 7 was colored dark green. I was seen.

The glass according to the present invention can be molded into lenses for automobile headlights, lenses for parlamps or reflectors, hollow bulbs, etc. according to well-known methods such as press molding and blow molding. Shows sex. The glass molded into a predetermined shape is used by being incorporated in a projection surface of a light source such as a mercury lamp or a metal halide lamp. By the glass of the present invention, harmful ultraviolet rays from the light source are cut and visible rays are efficiently transmitted, so that effective illumination can be performed without adversely affecting the irradiated object or the human body by the ultraviolet rays. Moreover, since the glass according to the present invention is excellent in heat resistance and chemical durability, it also effectively acts to protect the light source.

[0031]

As described above, the glass of the present invention is
Since borosilicate glass is used as the basic glass, heat resistance,
It has excellent chemical durability and does not break or lose transparency even near a high temperature light source or outdoors.

By adding a combination of ultraviolet absorbing components, it is possible to block ultraviolet rays harmful to the human body,
Since it has no absorption in the visible region, it can effectively cut only harmful rays emitted from the HID lamp.

Claims (3)

[Claims] 1. A borosilicate glass as a base glass, V ₂
At least two of O ₅ , Fe ₂ O ₃ , CeO ₂ , and TiO ₂ are 0.03 to 3 mass% (provided that V ₂ O ₅ 0.5
%, Fe ₂ O ₃ 0.3%, CeO ₂ 2%, TiO ₂ 2%
The glass for an HID lamp has a spectral transmittance at a thickness of 4 mm of 5% or less at 320 nm. 2. The base glass, in% by weight, comprises SiO ₂
55-85%, Al ₂ O ₃ 0.5-8%, Na ₂ O + K
₂ O + Li ₂ O 2-8%, CaO + MgO + BaO +
The HID according to claim 1, having a composition of 0.01 to 10% ZnO and 5 to 20% B ₂ O _3.
Lamp glass. 3. The spectral transmittance at a thickness of 4 mm is 300.
It is 1% or less in nm, The glass for HID lamps of Claim 1 or 2 characterized by the above-mentioned.