JP2582734B2 - Glass for fluorescent lamp - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to glass for fluorescent lamps, and more particularly to glass suitable for annular fluorescent lamps.

[Prior art and its problems] A fluorescent lamp stimulates a fluorescent substance with ultraviolet rays mainly emitted by a low-pressure mercury lamp to emit visible light. Generally, a fluorescent substance is coated on the inner wall of a glass tube, and both ends are coated. The electrodes are sealed, and their shapes are roughly classified into two types: straight tube and ring.

In recent years, fluorescent lamps have been continually improved in electrode structure, type of filling gas and pressure, optimization of fluorescent material, and improvement of light transmittance of bulb glass to improve the total luminous flux at the same power consumption. Efficient fluorescent lamps have been desired, and fluorescent lamps having various compositions have been conventionally proposed, but each has its own drawbacks.

For example, Japanese Patent Publication No. 52-33124 discloses an annular fluorescent lamp containing BaO and PbO. Certainly, when these components are contained, they have an excellent effect on lowering the viscosity of glass, but when BaO is contained, erosion of refractories in the melting furnace becomes remarkable, and when PbO is contained, the environment may be polluted. It is not preferable to contain these components.

Japanese Patent Application Laid-Open No. Sho 62-270234 discloses a glass for a health ray fluorescent lamp having a transmittance at a wavelength of 300 nm of 40% or more by setting the content of Fe ₂ O ₃ in the glass composition to 0.001 to 0.02%. Although it is disclosed, in order to reduce the content of Fe ₂ O ₃ as described above, the raw material cost of the glass, the iron removal cost in the glass manufacturing process is increased, and ultraviolet rays that are harmful to the human body below 260 nm are transmitted through ultraviolet rays It is not preferable because it is easy to perform.

[Object of the Invention] The present invention has been made in view of the above circumstances, and has a higher efficiency for fluorescent lamp glass than the conventional fluorescent lamp glass, specifically, the transmittance of visible light of 400 to 700 nm. It is an object of the present invention to provide a fluorescent lamp glass which is highly cost-effective, has excellent workability, can be produced at low cost, and has no fear of environmental pollution.

[Constitution of the Invention] As a result of repeated studies to achieve the above object, the present inventors have found that Sb ₂ O ₃ is strictly regulated to 0.4 to 0.8% and Fe ₂ O ₃ is strictly regulated to 0.03 to 0.05%. It is possible to improve the transmittance of visible light of 400 to 700 nm by, and find that it is possible to obtain a glass excellent in processability at a low cost and propose the present invention, that is, for the fluorescent lamp of the present invention Glass is SiO ₂ 65.0-75.0% by weight, Al ₂ O ₃ 0.5
~ 2.5%, MgO 1.0 ~ 5.0%, CaO 3.0 ~ 8.0%, MgO + Ca
O 5.5-9.5%, Na ₂ O 13.0-19.0%, K ₂ O 0-3.0
_{%, Na 2 O + K 2} O 13.0~20.0%, B 2 O 3 0.3~3.0%, P 2 O
_{5 0.1~1.0%, Sb 2 O 3} 0.4~0.8%, Fe 2 O 3 0.03~0.0
It is characterized by consisting of 5%.

In the present invention, the content of each component is limited as described above for the following reason.

SiO ₂ is the main glass-forming oxide, but if it is more than 75.0%, the solubility of the glass deteriorates and devitrification easily occurs, resulting in poor workability. If it is less than 65.0%, the water resistance decreases.

If the content of Al ₂ O ₃ is more than 2.5%, the solubility of the glass will be poor, and if it is less than 0.5%, the water resistance will decrease.

When MgO is more than 5.0% and CaO is more than 8.0%, devitrification tends to occur and workability is deteriorated. When the combined amount of both is more than 9.5%, coexistence with P ₂ O ₅ makes it easy to whiten the glass. Become. If MgO is less than 1.0% and CaO is less than 3.0%, or if the combined amount of both is less than 5.5%, the water resistance becomes poor.

Na ₂ O and K ₂ O are components that improve the solubility of glass and increase the coefficient of thermal expansion. However, when Na ₂ O is 19.0% or more or the total amount of both is more than 20.0%, the coefficient of thermal expansion is high. It becomes too much and the water resistance decreases. If the content of Na ₂ O is less than 13.0%, the coefficient of thermal expansion becomes too low, and the solubility of the glass becomes poor. When a part of Na ₂ O is replaced with K ₂ O, water resistance is improved. However, when K ₂ O is more than 3.0%, the viscosity of the glass is increased and the solubility of the glass is deteriorated.

B ₂ O ₃ has the effect of lowering the high-temperature viscosity of the glass and improving the water resistance, but if it is more than 3.0%, volatiles increase during melting of the glass. If it is less than 0.3%, it is difficult to obtain the above effect.

P ₂ O ₅ has the effect of lowering the liquidus temperature, but if it is more than 1.0%, opalescence of the glass tends to occur. If it is less than 0.1%, it is difficult to obtain the above effects.

The present invention, as described above, the transmittance in the visible light range,
To obtain glass for fluorescent lamps with excellent processability and productivity
Sb ₂ O ₃ is strictly regulated to 0.4 to 0.8% and Fe ₂ O _{3 to} 0.03 to 0.05% to be contained. In other words, Sb ₂ O ₃ has the effect of improving the transmittance of visible light of 400 to 700 nm and improving the defoaming of the glass, but if it is more than 0.8%, crystals due to antimony are likely to be generated. Therefore, the yield as a glass tube is deteriorated and the raw material cost is increased, which is not preferable. If it is less than 0.4%, the above effects cannot be obtained. Fe ₂ O ₃ is preferable to reduce the content of Fe ₂ O ₃ as much as possible in order to reduce the transmittance of visible light, especially the transmittance of visible light of 500 nm or less. It is not preferable that the content does not occur and that the content is less than 0.03%, because the raw material cost of the glass and the cost of removing iron in the glass manufacturing process increase, and harmful ultraviolet rays of 260 nm or less are easily transmitted.

[Examples] Hereinafter, the present invention will be described based on examples.

Table 1 shows examples of the glass of the present invention (sample Nos. 1 to 5),
It shows a thermal expansion coefficient and a light transmittance of a comparative example (sample No. 6) and each sample.

The glass of sample No. 6 which is a comparative example has 0.90% of Sb ₂ O ₃ and F
Although it is a conventional example containing 0.07% of e ₂ O _3, as can be seen from Table 1, the glass of sample No. 6 is the sample N of the embodiment of the present invention.
The light transmittance of visible light of 400 to 700 nm was lower than that of the glasses of Nos. 1 to 5, and the precipitation of crystals due to antimony was observed.

The coefficient of thermal expansion in the table is an average coefficient of thermal expansion between 30 and 380 ° C.

Table 2 shows the characteristics of a 30 W annular fluorescent lamp using a glass bulb made of the sample No. 4 glass and the sample No. 6 of Table 1.

The initial luminous flux in Table 2 is a relative value of the luminous flux of the lamp immediately after lighting for the first time.
In the case of 0%, the sample No. 4 of the present example showed a high value of 103.8%.

The luminous flux maintenance ratio was a relative value of the luminous flux maintenance ratio of the lamp after being turned on, and after 100 hours and 1000 hours, the sample No. 4 showed a higher value.

[Effect of the Invention] As described above, the glass for a fluorescent lamp of the present invention has a high visible light transmittance, can be produced at low cost, has no fear of environmental pollution, and has excellent workability. It is suitable as glass for lamps.

Claims (1)

(57) [Claims] (1) SiO _{2 in an} amount of 65.0 to 75.0% by weight, Al ₂ O ₃
0.5-2.5%, MgO 1.0-5.0%, CaO 3.0-8.0%, MgO
+ CaO 5.5 to 9.5%, Na ₂ O 13.0 to 19.0%, K ₂ O 0 to 3.
_{0%, Na 2 O + K} 2 O 13.0~20.0%, B 2 O 3 0.3~3.0%, P 2
O ₅ 0.1 ~ 1.0%, Sb ₂ O ₃ 0.4 ~ 0.8%, Fe ₂ O ₃ 0.03 ~ 0.
Glass for fluorescent lamps, characterized by comprising 05%.