JP4215912B2 - Thermal shock resistant UV blocking glass and UV blocking filter - Google Patents

Description

【００２７】
【発明の効果】
ホウケイ酸ガラスに紫外線吸収物質としてＣｅＯ_２を含有させる場合にガラスの主要構成成分であるＢ_２Ｏ_３の一部をＳｂ_２Ｏ_３で置換する本発明によれば、ホウケイ酸ガラスの特長である耐熱衝撃性を悪化させることなしに、シャープ且つ十分な紫外線遮断能と高度の化学的耐久性を備えた実質的に無着色の紫外線遮断ガラスを提供することができる。
【図面の簡単な説明】
【図１】 参考例１〜３および実施例２のガラスの分光透過率曲線である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultraviolet shielding glass having excellent thermal shock resistance and an ultraviolet shielding filter for an illumination device using a discharge lamp as a light source.
[0002]
In this specification, a glass product using the ultraviolet blocking ability is referred to as an ultraviolet blocking filter regardless of its main function and shape.
[0003]
[Prior art]
In order to use light from a lamp with ultraviolet radiation, such as a mercury lamp, for illumination, a filter that blocks harmful UV rays in the light emitted by the lamp and transmits only visible light, or a lamp that also functions as such a filter. A protective member is required.
[0004]
Various types of UV blocking filters are used depending on the application, but those for lighting devices have a severe temperature rise due to the heat generated by the lamp and are often used outdoors. Since it is often quickly cooled by getting wet with rainwater, etc., it is not only high in softening temperature, but also has excellent thermal shock resistance that does not break due to rapid heating / cooling. Must contain a good inorganic UV absorber.
[0005]
A typical example of what is used as the basic glass of the ultraviolet blocking glass for the above-mentioned uses because it has a small thermal expansion coefficient as an index of thermal shock resistance and excellent chemical durability is so-called borosilicate glass (Na ₂ O— a B ₂ O ₃ -SiO ₂ -based glass), examples of the ultraviolet absorbing material added _thereto, there is _{CeO 2, Fe 2 O 3,} V 2 O 5, TiO 2 , etc. (JP-B-61-24344 No. 6, JP-A-6-56467, JP-A-8-12369, etc.).
[0006]
However, one of the problems that are difficult to solve in the case of producing an ultraviolet blocking glass using borosilicate glass as a basic glass is to prevent a decrease in visible light transmittance due to an ultraviolet absorbing material to be added. In other words, borosilicate glass containing a sufficient amount of UV-absorbing substance for blocking ultraviolet rays often blocks visible light having a wavelength of 400 nm or more, so that the thickness of the filter usually used can be visually observed. However, since it is desirable that the filter for the general-purpose lighting device is practically colorless and transparent, a decrease in transmittance in the visible light region due to the ultraviolet absorbing material must be minimized.
[0007]
In order to solve this problem, in the inventions of JP-A-6-56467 and JP-A-8-12369, a limited amount of a plurality of ultraviolet absorbing substances are used in combination, but there remains a problem in sharp-cut properties. Even if such a means is adopted, if priority is given to avoiding coloring, the ultraviolet blocking ability in the near ultraviolet region has to be sacrificed to some extent.
[0008]
[Problems to be solved by the invention]
An object of the present invention is to provide a substantially uncolored UV-blocking glass having a low thermal expansion coefficient and a high degree of chemical durability equivalent to those of borosilicate glass, having a sharp and sufficient UV-blocking ability. It is in.
[0009]
Another object of the present invention is to provide a substantially uncolored high performance UV blocking filter comprising the above UV blocking glass.
[0010]
[Means for Solving the Problems]
In the present invention, when CeO ₂ is contained in the borosilicate glass as an ultraviolet absorbing substance, when a part of B ₂ O ₃ which is a main component of the borosilicate glass is replaced with Sb ₂ O ₃ , transmitted light and non-transmitted light are obtained. A boundary-free wavelength of about 360 to 380 nm is obtained, and a substantially uncolored glass excellent in sharp-cut property is obtained. Moreover, the thermal expansion coefficient is almost the same as that of borosilicate glass, and chemical durability is similar to that of borosilicate glass. It was completed on the basis of a novel finding that an ultraviolet blocking glass that is as good as it can be obtained.
[0011]
That is, the present _{invention, SiO 2 65~75%, Na 2} O 5~10%, 0~3% ZnO, Al 2 O 3 1.5~3%, CeO 2 0.5~2.5%, B ₂ O ₃ 0 to 10%, and the total amount of B ₂ O ₃ is 15 to 25% of Sb ₂ O ₃ is contained, whereby the transmittance of ultraviolet rays with a wavelength of 320 nm or less is 0%, wavelength 360 nm The composition is substantially colorless, characterized by having a near-ultraviolet transmittance of 50% or less, a transmittance of visible light having a wavelength of 400 nm of 72% or more, and a thermal expansion coefficient of 60 × 10 ⁻⁷ / ° C. or less. The present invention provides a heat-resistant shock-resistant UV-blocking glass and an UV-blocking filter for a lighting device using a discharge lamp comprising the UV-blocking glass (provided that% representing glass composition is% by weight and transmittance is 3 mm thick). The value measured for the plate, and so on. .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The ultraviolet blocking glass according to the present invention having the above composition is similar to a borosilicate glass containing CeO ₂ , but a large part of a large amount of B ₂ O ₃ characteristic of the borosilicate glass is substituted with Sb ₂ O _3. In addition, since Sb ₂ O ₃ is considered to be a glass network component, it can be said that it no longer belongs to the category of borosilicate glass. However, there is no particular difficulty in the production method, and it can be easily produced according to a conventional method for producing a general borosilicate glass.
[0013]
The constituent components will be described. First, SiO ₂ is set to 65 to 75%. However, if it is 75% or more, the melting temperature of the glass becomes too high, which is not preferable, and if it is 65% or less, the thermal expansion coefficient is increased and the structure is weak. Therefore, chemical durability is deteriorated and devitrification is likely to occur.
[0014]
If the Na ₂ O content is too small, the viscosity of the glass increases and the solubility becomes poor.
[0015]
B ₂ O ₃ which is the main component of the base glass together with the above two components is less than that of a typical borosilicate glass, and is 10% or less, preferably 3 to 10%. If it is more than this, even if Sb ₂ O ₃ is added, no sharp ultraviolet blocking property can be obtained, and it will be colored yellow.
[0016]
When Sb ₂ O ₃ is added to a borosilicate glass not containing CeO ₂ , it hardly affects the transmittance of ultraviolet rays and visible light. However, in the case of CeO ₂ -added borosilicate glass, when Sb ₂ O ₃ is added, the transmittance is remarkably improved in a wide wavelength range from near ultraviolet to visible light having a wavelength of about 350 nm or more, thereby blocking ultraviolet rays by CeO _2. As well as improving the sharp cutting property, the coloring is virtually eliminated. The reason may be that yellow Ce ⁴⁺ is changed to colorless Ce ³⁺ by the added Sb ₂ O ₃ , but it is not confirmed. Increasing the transmittance of near-ultraviolet light having a wavelength of about 350 nm or more together with visible light seems disadvantageous from the viewpoint of complete blocking of ultraviolet light, but there are cases where ultraviolet light in this wavelength range can be used effectively (Japanese Patent Laid-Open No. 8-12369). No.), harmful effects are also weak. Further, since the transmittance of ultraviolet rays having a wavelength of 320 nm or less, which is highly harmful, is not increased at all, there is no practical problem.
[0017]
Said based on Sb ₂ O ₃ addition effect is manifested by _Sb 2 _{O 3} of more than about 5% saturated with amount around 20%. As the Sb ₂ O ₃ addition amount increases, the spectral transmittance curve near the wavelength of 350 to 380 nm slightly shifts to the longer wavelength side.
[0018]
The addition of Sb ₂ O ₃ also helps to improve chemical durability and gives a glass with better chemical durability than borosilicate glass.
[0019]
Incidentally, only the addition of CeO ₂ and _Sb 2 _{O 3} in the borosilicate glass becomes large, the thermal expansion coefficient of the glass, but the thermal shock resistance is deteriorated, it is, _B 2 _{O 3} in accordance with _Sb 2 _{O 3} added amount If the total amount of Sb ₂ O ₃ and B ₂ O ₃ is in the range of 15 to 25% (preferably about 17 to 20%), it can be almost completely prevented, Those having an expansion coefficient of 60 × 10 ⁻⁷ / ° C. or less can be easily obtained (the thermal expansion coefficient of general borosilicate glass is about 50 × 10 ⁻⁷ / ° C.).
[0020]
ZnO and Al ₂ O ₃ are not related to the ultraviolet blocking ability, but if a small amount is added, it is effective to improve the chemical durability of the glass.
[0021]
An appropriate amount of CeO ₂ which is the main agent for blocking ultraviolet rays is about 0.5 to 1.6%, and at most about 2.5%. If the amount is larger than this, even if a large amount of Sb ₂ O ₃ is added, the transmittance decreases over the visible light region, and coloring becomes conspicuous when the plate thickness when used as a filter is large.
[0022]
When the raw material mixture selected and prepared according to the conventional method for glass production is vitrified by heating to a molten state so as to have the above composition, the transmittance of all ultraviolet rays having a wavelength of 320 nm or less is 0%. A substantially colorless thermal shock resistant ultraviolet ray having a near-ultraviolet ray transmittance at a wavelength of 360 nm of 50% or less, a visible light transmittance at a wavelength of 400 nm of 72% or more, and a thermal expansion coefficient of 60 × 10 ⁻⁷ / ° C. or less. A barrier glass can be obtained.
[0023]
If this is formed into a disk shape or any other shape necessary for manufacturing lamps and filters by any method, and polished as necessary, a substantially colorless UV blocking filter having high thermal shock resistance can be obtained. be able to.
[0024]
【Example】
Next, the present invention will be described with reference to specific examples.
Standard borosilicate glass (Reference Example 1) having the composition shown in Table 1 and eight kinds of ultraviolet blocking glasses (Comparative Examples 1 to 3 and Examples 1 to 1) containing CeO ₂ while changing part of the composition. 5) was produced. The obtained glass and the borosilicate glass of Reference Example 1 were measured for thermal expansion coefficient and alkali elution amount, and further measured for spectral transmittance in the ultraviolet and visible light regions having a wavelength of 300 or more. The thermal expansion coefficient was measured according to JIS R3102, and the alkali elution amount was measured according to JIS R3502, respectively. The results are shown in Table 1. The total visible light transmittance is an average transmittance in a wavelength range of 380 to 780 nm.
[0025]
Moreover, the spectral transmittance curve measured about the glass of the following reference examples 2 and 3 which made the borosilicate glass of the reference example 1 the basic glass and contained the ultraviolet-absorbing substance, and the said reference example 1 and Example 2 is shown. It was shown in 1.
Reference Example 2: Borosilicate glass containing 1.4% CeO ₂ Reference Example 3: Borosilicate glass containing 0.8% CeO ₂ and 0.1% TiO ₂
[Table 1]

[0027]
【The invention's effect】
According to the present invention, a part of B ₂ O ₃ which is a main component of glass is substituted with Sb ₂ O ₃ when CeO ₂ is contained in the borosilicate glass as an ultraviolet absorbing substance. Without deteriorating the thermal shock resistance, it is possible to provide a substantially non-colored UV blocking glass having a sharp and sufficient UV blocking ability and a high chemical durability.
[Brief description of the drawings]
1 is a spectral transmittance curve of glasses of Reference Examples 1 to 3 and Example 2. FIG.

Claims (5)

SiO ₂
65-75 _wt%, Na 2 O _5~10 wt%, ZnO 0 to 3 _{wt%, Al} 2 O 3 _1.5~3 wt%, CeO ₂
0.5-2.5 _{wt%, B} 2 O 3 0 wt%, and _B 2 _{O 3} the total amount of is 15 to 25 wt% amount of _Sb 2 _{O 3}
Therefore, the transmittance of ultraviolet light having a wavelength of 320 nm or less is 0%, the transmittance of near ultraviolet light having a wavelength of 360 nm is 50% or less, the transmittance of visible light having a wavelength of 400 nm is 72% or more, and the thermal expansion coefficient is A substantially colorless thermal shock-resistant UV-blocking glass characterized in that it is 60 × 10 ⁻⁷ / ° C. or less (however, the transmittance is a value measured for a plate having a thickness of 3 mm). The thermal shock-resistant ultraviolet blocking glass according to claim 1, wherein the B ₂ O ₃ content is 3 to 10% by weight.   The thermal shock-resistant ultraviolet blocking glass according to claim 1 or 2, wherein the ZnO content is 1 to 3% by weight. Thermal shock resistance ultraviolet screening glass according to any one of claims 1 to 3 containing an amount of _Sb 2 _{O 3} the total amount of B ₂ O ₃ is 17 to 20 wt%.   An ultraviolet blocking filter for an illumination device using a discharge lamp, comprising the ultraviolet blocking glass according to any one of claims 1 to 4.

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