JPS60161352A - Glass for annular fluorescent lamp - Google Patents

Abstract

PURPOSE:To obtain the titled glass which is easily bendable, and has excellent lamp characteristics, chemical durability, and resistance to devitrification by composing the glass of SiO2, Al2O3, Na2O, K2O, Li2O, CaO, MgO, BaO, SrO, PbO, B2O3, etc. in specified composition. CONSTITUTION:The composition is composed of 60-75%, by weight, SiO2, 0.5- 4% Al2O3, 12-17% Na2O, 0-3% K2O (however 0 is not included, and the same shall apply hereinafter), 0-1% Li2O, 13-18.5% Na2O+K2O+Li2O, 1- 8% CaO, 0.5-3% MgO, 0-2% BaO, 0-2% SrO, 0.1-2% PbO, 0.1-2.5% BaO+ SrO+PbO, 0-3% B2O3, 0-0.6% As2O3, 0-0.5% Sb2O3, and 0.02-0.8% As2O3+ Sb2O3. The composition is then melted to obtain the titled glass.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a glass for annular fluorescent lamps, and more particularly to a glass composition having excellent heat processability.

[Technical background of the invention]

In general, annular fluorescent lamps are manufactured by coating the inner wall of an airtight container made of straight glass with a phosphor, sealing both ends of the stem that holds the electrodes, and heating this in an electric furnace or the like to
The glass used to form this airtight glass container is softened by heating to 00°C and wound around a forming drum to form a ring shape. Conventionally, the glass used to form this glass airtight container is made of lead oxide pbO 4. A lead glass containing ~28% by weight was used.

Recently, attempts have been made to use soda lime glass, which is used in glass bulbs for straight tube fluorescent lamps and general lighting bulbs, for the purpose of weight reduction and cost reduction, and although some are already on the market, there are still problems. was left behind.

[Problems with background technology]

In general, glass containing a large amount of PbO (hereinafter referred to as lead glass) suffers from the scattering of lead raw materials during glass melting or molding.
In order to prevent environmental pollution due to the volatilization of lead components during processing, a large amount of work environment maintenance costs are required, and raw material costs also increase, and the product itself becomes heavier.

For this reason, a switch has been made to soda-lime glass, which is cheaper and has a lower specific gravity. However, since soda-lime glass has a thermal processing temperature approximately 100°C higher than the above-mentioned lead glass, the yield rate during processing is affected, as well as the fluorescence. Physical and chemical reactions occur between the body or binder and the glass tube, resulting in deterioration of the phosphor and deterioration of the initial luminous flux and luminous flux maintenance rate of the annular fluorescent lamp.

Therefore, it is essential for glass for annular fluorescent lamps to have viscosity properties that can be easily bent, and this requires that the softening temperature be as low as possible and the viscosity curve near the working temperature be gentle. A wide working temperature range is desired.

In addition, the expansion coefficient is 91 to 103 in the temperature range of 0 to 300°C due to the sealing property with stem glass using lead glass.
It is limited to a range of X 10-'/. Regarding chemical durability, problems such as alkali content and precipitation may occur due to weathering during storage, and a test based on the new Osaka Industrial Testing Method requires 8 m-Q/N/100HCfi or less.

A glass composition that satisfies all of the above characteristics has not yet been developed.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its object is to provide a soda-lime-based glass with good heat processability in order to improve Lang properties as a glass for annular fluorescent lamps. .

[Summary of the invention]

In order to achieve the above object, the present invention introduces 0.1 to 2% of PbO into the conventional soda-lime glass and makes it coexist with BaO and SrO.
Alternatively, a glass composition has been developed that is more luxurious and has superior heat processability compared to soda-lime-based glasses that mainly incorporate B2O3, BaO, and SrO.

In other words, the initial luminous flux and luminous flux maintenance rate as lamp characteristics are:
This is the most important characteristic of a lamp's operating cycle, and the inventors have found that the physical and chemical reactions between the glass material, binder, and phosphor at high temperatures have the greatest influence. I found out that

To achieve this, the bending temperature during ring forming should be kept as low as possible to prevent deterioration of the phosphor and binder.
It is necessary to prevent the glass bulb from digging into the pipe wall. In general, increasing the alkali oxide content of soda-lime glass lowers the softening temperature and improves thermal processability, but on the other hand, it deteriorates chemical durability, causes weathering, and increases the coefficient of expansion. Due to the problem of sealing properties with stem gas, it is not possible to increase the number of stem gases. As a result of various experiments, the present inventors have found that adding a small amount of PbO to soda-lime glass significantly improves thermal processability, and that the effect is further improved by coexisting BaO, SrO, and PbO. was found to be significant.

That is, the gist of the present invention is 5iO260-75% by weight percentage.
, kL20s O, 5-4%, Na, 012-17%,
K2O0~3% (however, 0 is not included) Liz00~1% (
However, 0 is not included, and the sum of Na2O, 20 and Li2O is 13-18.5%)0601-8%, M5i00.
5-3%, BaO 0-2% (including 0゛), 8
r00. ~2% (including 0) Input Pb00.1~2%
, (However, the sum of BaO, SrO and PbO is 0.2 to 2.
5%), B20sO ~ 3% (excluding O) bAsz
ch O ~ 0.6% (not including O), 5bzOs
O ~ 0.5% (however, does not include 0, and contains Ag2O3 and 5b
This is a glass for annular fluorescent rung having a composition of 0.02 to 0.8%).

Next, the reason for limiting the numerical value of the above composition range will be explained in detail.

s io, is one of the essential components for glass formation, but 6
If it is less than 0%, the expansion coefficient is high (and the chemical durability deteriorates, which is undesirable. If it exceeds 75%, the expansion coefficient becomes too low, the softening temperature becomes high, and ring formation becomes difficult. Desirably 65%). If Afi203 is less than 0.5%, the chemical durability will deteriorate, and if it exceeds 4%, the glass will become non-uniform and the number of striae defects will increase.It is preferably 1 to 3%.

If the sum of Na*020 and Li1O is less than 12% or 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.

Also, Nano was 17%%, KxO was 3%, and Na
, o, and if the sum of O and Li2O exceeds 18.5%, the expansion coefficient becomes too large and the chemical durability and electrical insulation properties decrease. Although Li 20 has a great effect on promoting melting even when added in a small amount, it is expensive, so it was limited to 1% or less.

Alkaline earth metal oxides of CaO and MjIO improve electrical insulation and chemical durability, but CaO1%
If the content and M content are less than 5%, no effect can be expected, and if the content exceeds 3% CaO and 3%, the glass tends to devitrify, which is not preferable. Further, although CaO and MjIO have the effect of lowering high temperature viscosity, they have the effect of increasing viscosity below the working temperature range, so they are not preferred for the purpose of lowering the softening temperature.

The present invention adds 0.1 to 2 PbO as one of the essential components to Banji soda lime glass in order to improve workability during ring forming.
% added, combined with BaO9~2% and 5r00~2%
is added, and the total amount of PbO, BaO, and SrO is 0.
It is distinctive in that it is set to 2 to 2.5%. That is, p
If the total amount of PbO, BaO and SrO is less than 0.2%, the viscosity near the working temperature cannot be lowered, and if PbO exceeds 2% and PbO and BaO The total amount with SrO is 2. ．． If it exceeds 5%, the tendency towards devitrification increases, which is not preferable.

B2O3 improves melting properties and chemical durability, but if it exceeds 3%, it increases the softening temperature and tends to cause scum during melting, which is not preferred. Asz
Both os and 5bzOs are used as refining agents, and also have the effect of maintaining molten glass in an oxidizing atmosphere and preventing glass coloring due to Fe"+, but when the total amount is 0.
．． If it is less than 0.02%, no effect can be expected, and ASzOa
0.6%, and 8bzOs 0.5% and As, 0.
If the total amount of Sb 20m and Sb 20m exceeds 0.8%, it is not preferable because foaming may occur again during heat processing, resulting in defective foaming.

[Embodiments of the invention]

The present invention will be explained in detail below. Table 1 shows examples of the glass for annular fluorescent lamps according to the present invention and comparative examples of conventional products.

Table 1 Comparative Example 1 is a conventional example of lead glass, and Comparative Example 2 is a conventional example of soda lime glass before improvement. Examples 1 to 6 are examples according to the present invention.

The expansion coefficient is the average thermal expansion coefficient between 0 and 300°C, and the softening temperature is the temperature corresponding to the viscosity xo7Js voids, respectively. The values measured in accordance with ``Method'' are shown.

As for the working temperature, the temperature corresponding to viscosity of 10' voids was read from the high temperature viscosity measurement curve, and the value was displayed.

According to the embodiment of the present invention, the processing temperature during ring forming is lower than that of the conventional soda lime glass shown in Comparative Example 2;
It is understood that the working temperature was almost close to that of , and that the thermal processing was easy.

Furthermore, as representative examples among the above-mentioned examples, Example No. and INo.
, 30W using 3 and N095 glass bulbs
A prototype ring-shaped fluorescent lamp was manufactured and the lamp characteristics were evaluated. Table 2 shows a comparison of the lamp characteristics between the lamps manufactured in Examples No., I No. 2k, and No. 005 and the conventional comparative examples No. 1 and Nα2.

As shown in the table above, the annular fluorescent lamp using the example glass according to the present invention had significantly improved lamp characteristics as compared to the conventional soda-lime glass, and the yield in the manufacturing process was also good. It also had good sealing properties with stem glass, and cracks and leak defects that occurred during the process were comparable to those of current glass.

〔Effect of the invention〕

As explained above, the glass for annular fluorescent lamps according to the present invention has good heat processability, good lamp properties, and excellent chemical durability and devitrification resistance, and can be used as a tube glass for both straight tube and ring shapes. can also be used.

Patent applicant: Toshiba Glass Corporation

Claims (1)

[Claims] 8i0z 60-75% by weight percentage, Al-2030
,5~4%, N172012~17%, N200~3%
(However, 0 is not included), Liz00~1% (However, 0 is not included, and the sum of 0 and Li2O is 13~1.
8.5%), Ca01-8%, Mfoo, 5-3. %
, Ba0O~2% (excluding 0), 5r00~2%
(however, 0 is not included), Pb00.1~2% (however, Ba
The sum of O, 8rO and PbO is 0.1 to 2.5%), B2
O30~3% (excluding 0), Ag2O30~0.
6% (excluding 0), 5bzOs O~0.5% (
A glass for an annular fluorescent lamp characterized in that it does not contain O and has a composition in which the sum of As2O3 and 5bzOa is 0.02 to 0.8%.