JPH0433742B2 - - Google Patents

Description

[Detailed description of the invention]

[Object of the Invention] (Industrial Field of Application) The present invention relates to a glass for annular fluorescent lamps having good heat processability and lamp properties. (Prior art) In general, annular fluorescent lamps are manufactured by coating the inner wall of an airtight container made of straight glass with a phosphor, sealing a system for holding electrodes at both ends, and placing this in an electric furnace or the like. The material is softened by heating to 750 to 870°C, then wound around a forming drum and formed into a ring shape. Conventionally, lead glass and soda lime glass have been used to form the glass airtight container. (Problems to be solved by the invention) Generally, glass containing a large amount of PbO (hereinafter referred to as lead glass) prevents environmental pollution caused by scattering of lead raw materials and volatilization of lead components during glass melting or molding/processing. As a result, there were drawbacks such as a large amount of work environment preparation costs, an increase in raw material costs, and an increase in the weight of the product itself. For this reason, a switch has been made to soda lime glass, which is cheaper and has a lower specific gravity.
As the temperature increases, not only the yield during processing but also physical and chemical reactions occur between the phosphor and binder and the glass tube, resulting in deterioration of the phosphor and the initial luminous flux and luminous flux of the annular fluorescent lamp. A problem arose that deteriorated the retention rate. The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide soda lime glass for a fluorescent lamp, which can improve the lamp characteristics of initial luminous flux and luminous flux maintenance rate. [Structure of the Invention] (Means and Effects for Solving the Problem) In order to achieve the above object, the present invention uses BaO, B ₂ O ₃ , Li ₂ as essential components in soda lime glass.
Specific amounts of O and F were introduced. BaO has the effect of acting as a fluxing agent and lowering the softening temperature, B ₂ O ₃ has the effect of lowering the viscosity and coefficient of thermal expansion, and is effective for low expansion, chemical durability, and heat resistance, and Li ₂ O has a trace amount ( Addition of F (0.5% or less) has the effect of greatly lowering the viscosity, and F is 1%.
The addition of has the effect of lowering the softening temperature by approximately 30°C.
The introduction of essential components that have these effects improves heat processability and allows processing at low temperatures, which prevents physical and chemical reactions between the phosphor and binder and the glass, so the phosphor is No deterioration occurs, and lamp initial luminous flux and luminous flux maintenance rate are improved. That is, the present invention uses SiO ₂ 60-75 in weight percentage.
%, _{A2O3 0.5} ~5%, _Na2O12 ~17%, _K2O0 ~
3%, Li ₂ O 0.05-3%, total amount of Na ₂ O, K ₂ O, Li ₂ O 13-19%, CaO 1-8%, MgO 0.2-3%,
BaO0.2~10%, B ₂ O ₃ 0.1~5%, F0.01~1%,
This is a glass for an annular fluorescent lamp containing 0.1 to 0.5% of Sb ₂ O ₃ . Next, the reason for limiting the numerical value of the above composition range will be explained in detail. SiO ₂ is one of the essential components for forming glass, but if it is less than 60%, the expansion coefficient becomes high and chemical durability deteriorates, which is not preferable. Moreover, if it exceeds 75%, the expansion coefficient becomes too low and the softening temperature becomes high, making it difficult to form a ring. Preferably
It is 65-73%. When A ₂ O ₃ is less than 0.5%, the chemical durability deteriorates, and when it exceeds 4%, the glass becomes non-uniform and the number of striae defects increases. It is preferably 1 to 3%. If the Na ₂ O content is less than 12% and the sum of Na ₂ O, K ₂ O, and LiO is less than 13%, the softening temperature will be high, making it difficult to form a ring, and the expansion coefficient will also be too low.
In addition, Na ₂ O is 17%, K ₂ O is 3%, and Na ₂ O
If the sum of K ₂ O and Li ₂ O exceeds 18.5%, the expansion coefficient becomes too large and the chemical durability and electrical insulation properties decrease. Although Li ₂ O has a great effect on promoting melting even when added in a small amount, if it exceeds 3%, it tends to cause devitrification. Alkaline earth metal oxides of CaO and MgO improve electrical insulation and chemical durability, but
If CaO is less than 1% and MgO is less than 0.5%, the effect cannot be expected, and if CaO is more than 8% and MgO is more than 3%, there is a strong tendency to devitrify the glass, which is not preferable. Further, although CaO and MgO have the effect of lowering high-temperature viscosity, they increase the viscosity below the working temperature range, so they are not preferred for the purpose of lowering the softening temperature. BaO is added as an essential component because it has the effect of lowering the viscosity of glass even if the content of alkaline components is reduced, but if it is less than 0.2%, no noticeable effect can be obtained, and if it exceeds 10%, it is difficult to remove bubbles. This is not preferable because the temperature range becomes narrower and workability deteriorates. B ₂ O ₃ improves meltability and chemical durability, but if it is less than 0.1%, it has no effect.
If it exceeds 5%, it is not preferable because it increases the softening temperature and generates scum during melting. F is added as an essential component because even a small amount of F lowers the viscosity of the glass, but if it exceeds 1%, it tends to cause devitrification and is not preferred. _Sb2O3 along with _NaNO3 is used as _a refining agent and also maintains the molten glass in an oxidizing atmosphere,
It also has the effect of preventing glass coloring due to Fe ²⁺ , but if it is less than 0.1%, no clarification effect can be expected;
If it exceeds %, it is not preferable because it may re-foam during heat processing and cause foam defects. (Example) Examples of the present invention are shown in Table 1. No. 1 to No. 6 are examples. The comparative example is a conventional example of soda lime glass. Furthermore, a 30 Watt annular fluorescent lamp was prototyped using the glass bulb of the above example, and the initial luminous flux and luminous flux maintenance rate of the lamp were evaluated. Table 2 shows a comparison of lamp characteristics between the lamp of this example and a conventional product.

【table】

【table】

〔Effect of the invention〕

As explained above, the glass for annular fluorescent lamps according to the present invention has good thermal processability and can lower the molding temperature of the lamp, thereby preventing deterioration of the phosphor and improving the initial luminous flux and luminous flux maintenance rate of the lamp. and chemical durability. Although the present invention has been described as a glass for annular fluorescent lamps, it is of course applicable to glass for general lighting as it has excellent heat processability and chemical durability.

Claims (1)

[Claims] 1 SiO ₂ 60-75%, A ₂ O ₃ 0.5-5 in weight percentage
%, _Na2O12 ~17%, _K2O0 ~3%, _Li2O0.05 ~3
%, total amount of Na ₂ O, K ₂ O, Li ₂ O 13-19%, CaO1
~8%, MgO0.2~3%, BaO0.2~ ₁₀ %, _B2O3
Glass for annular fluorescent lamp containing 0.1-5%, F0.01-1%, Sb ₂ O ₃ 0.1-0.5%.