JP2003073142A - Glass composition for illumination - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass composition for illumination containing no lead nor sodium, and less in surface degradation by weathering while keeping excellent thermal processability and electric insulation required for the glass for illumination. SOLUTION: The glass composition comprises 60 to 70% of SiO2 , 2 to 5% of Al2 O3 , 1 to 5% of Li2 O, 9 to 15% of K2 O, 10 to 18% of Li2 O+K2 O, 0 to 6% of CaO, 0 to 3% of MgO, 1 to 6% of BaO, 1 to 8% of SrO, 8 to 20% of MgO+CaO+BaO+SrO, 0.5 to 3% of B2 O3 , 0 to 1% of Sb2 O3 , 0 to 3% of TiO2 , and 0 to 1% of CeO2 in terms of mass %.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass composition for lighting which is substantially free of lead and sodium for use in fluorescent lamps and incandescent lamps, and has a harmful ultraviolet ray transmission amount emitted during lamp lighting. And a glass composition for lighting having excellent weathering resistance.

[0002]

2. Description of the Related Art Conventionally, a main tube of a fluorescent lamp or an incandescent lamp and a light bulb have a soft soda lime glass excellent in workability, and a stem portion for sealing the introduction gland to the fluorescent lamp or the incandescent lamp. , Which has sufficient electric resistance to prevent the occurrence of leakage current, and has good thermal processability that softens at a relatively low temperature,
Lead-based glass containing 20 to 30 mass% PbO has been used.

However, lead is a toxic substance, and the volatilization of the lead component during the melting and processing of the lead-based glass and the scattering from the raw materials adversely affect the worker, and the emission and use into the atmosphere from the manufacturing process. In recent years, development of alternative glass compositions that do not contain lead has been progressing in the field of glass products as well, because it is feared that the diffusion of used products will cause environmental pollution.

Further, from the viewpoint of environmental protection, the development of a glass composition capable of reducing the amount of mercury enclosed in a fluorescent lamp is under way.

However, in the case of soda-lime type glass, the adverse effect of sodium in the glass on the lamp has been found in recent years. First, there is a deterioration in the phosphor due to the reaction between sodium and the phosphor. Phosphor degradation not only causes visual defects,
This leads to a decrease in light output over time and a shortened lamp life.

Secondly, sodium contained in the glass reacts with mercury vapor in the lamp to form an amalgam. Amalgam occurs as black deposits on the inner wall of the glass tube, which not only causes a defect in appearance but also causes a decrease in light emission amount. In addition, at the time of making the lamp, the amount of mercury was reduced in advance due to the formation of amalgam, and the amount of mercury was filled in advance in excess of the amount required for lighting, which is against the trend of reducing the amount of environmentally hazardous substances used in recent years. .

Illumination glasses that do not contain lead include those disclosed in, for example, JP-A-6-206737 and JP-A-9-12.
332, JP-A-10-152340, JP-A-11-224649, and JP-A-2000-1036.
For example, those described in Japanese Patent No. 37 are available. These glasses contain a relatively large amount of alkaline earth metal elements such as BaO and SrO and have the same electrical insulating properties as lead glass, and at the same time have a high workability by increasing the content of alkali metal elements. Is.

However, each of the above-mentioned glasses has a composition containing a large amount of sodium in order to have thermal processability close to that of lead glass, and the above-mentioned mercury consumption problem cannot be solved.

Therefore, as a countermeasure against the above-mentioned various problems, a method of preventing the reaction of sodium with mercury and the phosphor by forming a protective film between the inner wall of the lamp and the phosphor has been considered. However, in addition to the problem that the protective film is not formed at the sealing portion between the stem and the main tube and the stem portion, it is not economically preferable because it involves an increase in the number of manufacturing steps and an increase in production cost.

[0010] Therefore, as a more efficient means, there is an idea to use a glass containing no sodium component to fundamentally eliminate the reaction with the phosphor and mercury. As a lighting glass containing almost no sodium component to reduce the consumption of mercury, for example, Table 1
There is one described in Japanese Patent Laid-Open No. 1-509514. This glass contains Li ₂ O, K ₂ O and alkaline earth metal oxides at a high rate instead of reducing the Na ₂ O content to less than 0.1%, and is equivalent to conventional soda lime glass. It realizes the characteristics of.

[0011]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention [Table 1]
The soda-free glass disclosed in Japanese Patent Publication No. 9514 needs to use a large amount of expensive raw materials Li ₂ O and K ₂ O, which inevitably increases the product price and is not preferable from an economical point of view. . Further, since this glass contains BaO at a relatively high rate, the erosion of the furnace material is severe during melting,
Problems such as shortening of the life of the melting furnace and occurrence of defective spots due to eroded refractory materials become problems. Furthermore, there is also a problem that devitrified substances are easily generated when the tube is formed by the Dunner method.

Such a soda-free glass for lighting is
The purpose of the present invention is to prevent the formation of amalgam with mercury and the deterioration of the phosphor due to sodium, thereby preventing the decrease of the lamp brightness. However, deterioration of the glass surface during storage of the semi-finished product or use of the product due to the influence of moisture in the air, or so-called weathering, which causes white fogging, also causes a decrease in lamp brightness. Therefore, in order to make the glass suitable for lighting applications, it is necessary to have a property excellent in weathering resistance.

The present invention has been made in consideration of such circumstances, and it is substantially free of sodium, and weathering while maintaining excellent heat workability and electric insulation required for lighting glass. It is an object of the present invention to provide a glass composition for lighting, which has less surface deterioration due to

[0014]

According to the present invention, in order to achieve the above object, the mass percentage of SiO _{2 is} 60 to 70%,
Al ₂ O ₃ 2-5%, Li ₂ O 1-5%, K ₂ O 9-
15%, Li ₂ O + K ₂ O 10-18%, CaO 0-
6%, MgO 0-3%, BaO 1-6%, SrO 1
~ 8%, MgO + CaO + BaO + SrO 8-20
%, B ₂ O ₃ 0.5 to 3%, Sb ₂ O ₃ 0 to 1%, Ti
It is characterized by containing O ₂ 0 to 3% and CeO ₂ 0 to 1%.

Next, the function of the components constituting the glass of the present invention and the reason why the content is limited as described above will be explained.

SiO ₂ is a glass network-forming component, but if it is less than 60%, the chemical durability of the glass tends to be low.
If it exceeds 70%, the meltability and processability of the glass deteriorate and the coefficient of thermal expansion becomes too small.

Al ₂ O ₃ has the effect of improving the chemical durability of the glass, but if it is less than 2%, phase separation occurs in the glass and molding is difficult, and if it exceeds 5%, striae occur and the glass is homogeneous. Glass cannot be obtained, and devitrification becomes stronger.

Li ₂ O and K ₂ O act as a flux to improve the meltability of glass. At the same time, it has the effect of adjusting the thermal expansion coefficient of the glass, but if the total amount of these is less than 10%, the viscosity becomes high and the meltability deteriorates. Also, the total amount is 18%
If it exceeds, the chemical durability is lowered and the coefficient of thermal expansion becomes too high, which is not preferable. In addition, since these alkali metal oxides produce a mixed alkali effect when they coexist and enhance the electric insulating property, it is preferable to add them in a mixed manner, not alone. If K ₂ O is less than 9%, the effect of adjusting the thermal expansion coefficient and viscosity of the glass cannot be obtained, and if it exceeds 15%, the thermal expansion coefficient becomes too high and the chemical durability is deteriorated, which is not preferable. When the content of Li ₂ O is less than 1%, the amount of K ₂ O added must be increased in order to obtain good meltability and heat processability, and the chemical durability decreases, which is not preferable. . Further, when Li ₂ O exceeds 5%, the thermal expansion coefficient becomes too high, which is not preferable.

BaO is a component that imparts high electrical insulation to glass, but if it is less than 1%, the desired electrical insulation cannot be obtained, and if it exceeds 6%, the erosion of the molten furnace material becomes remarkable, and the content of BaO This increases the number of defective spots and causes devitrification when forming a tube by the Dunner method. The upper limit is preferably 5%
Up to

Similar to BaO, SrO contributes to the electrical insulating property of glass, but if it is less than 1%, the desired electrical insulating property cannot be obtained, and if it exceeds 8%, the devitrification tendency increases and the raw material cost rises. The upper limit value is preferably up to 7%.

MgO and CaO each have a function of lowering the softening point of glass and have the effect of improving the chemical durability of glass by adding up to the above upper limit values, but if added over the respective upper limit values, the glass will be lost. It is not preferable because it becomes easy to see through.

MgO, CaO, BaO and SrO have a function of enhancing the electrical insulating property of the glass as a whole, but if the total amount of these is less than 8%, the effect is insufficient as a glass for illumination and exceeds 20%. And the tendency of glass to crystallize increases. The upper limit is preferably set to 17%.

A small amount of B ₂ O ₃ has the effect of improving the meltability of glass and chemical durability.
If it is less than 0.5%, its sufficient effect cannot be obtained, and if it is added in excess of 3%, the thermal expansion coefficient becomes too small. Preferably, the upper limit value is up to 2.5%.

TiO ₂ has the effect of improving the chemical durability with a small amount and imparting excellent weathering resistance, and also has the function of blocking the ultraviolet rays emitted from the lamp, but if added in excess of 3%, the meltability is increased. And the appearance defects due to the coloring of the glass are likely to occur. Preferably, the upper limit value is up to 2.5%. It is also known that glass has a coloring phenomenon called solarization, which is caused by long-term exposure to ultraviolet rays. If the lighting glass is inferior in this resistance, the lamp causes a decrease in luminous flux with the passage of time and lighting. TiO ₂ is
Since it also has the effect of suppressing solarization, it is preferable to add at least 0.05% or more in order to maintain its resistance.

Both TiO ₂ and Al ₂ O ₃ have the effect of improving the chemical durability of glass, but if their total amount is less than 2.5%, sufficient chemical durability cannot be obtained, and weathering will not occur. Likely to happen. If the total amount exceeds 6%, the meltability and devitrification deteriorate. The upper limit of the total amount is preferably 5%.

Fluorescent lamps emit mercury from mercury by arc discharge.
The emitted ultraviolet light excites the phosphor to emit light.
It At this time, some ultraviolet rays are emitted from the lamp, but
UV rays are harmful to the human body, so their emission is 10
0.001W / m per 00lm ²Regulated to be
(JEL601 light source product safety). CeO_TwoIs a small amount
And has the effect of imparting good UV blocking properties
However, even if the added amount exceeds 1%, its effect does not change, and
Do not add more than 1% as it may cause coloration of the pair.
And are preferred.

TiO ₂ and CeO ₂ each have an effect of blocking harmful ultraviolet rays, but their total amount is 0.0
If it is less than 5%, the effect is insufficient, and if it exceeds 3%, the tendency of coloring and devitrification of the glass is increased. Preferably, the total upper limit is 2.5%.

Sb ₂ O ₃ not only acts as a fining agent when the glass is melted, but also has the effect of suppressing solarization. However, if its content increases, the blackening phenomenon of the glass tends to occur during processing with a burner, so the upper limit is set to 1
Up to%. Also, coexistence with CeO ₂ is not preferable because it adversely affects the ultraviolet solarization resistance, and when these components coexist, Sb ₂ O ₃ is 0.5%.
It is preferable that

As components other than the above, F, SO ₃ , Cl, Fe ₂ O ₃ and Zn are used as long as the object of the present invention is not impaired.
It is possible to add or contain components such as O and ZrO ₂ . Of these, ZrO ₂ has the effect of improving the weather resistance of the glass, so it is possible to intentionally add it up to about 1%, but since it deteriorates the meltability, ZrO ₂ is limited to at most 2%. preferable. Further, Fe ₂ O ₃ has an effect of blocking ultraviolet rays, so that the effect can be utilized, but if it is contained in excess, it causes coloring in the glass.
It is preferable to suppress it to about 05 to 0.05%.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. The glass of the present invention can be manufactured as follows. First, the above composition range, for example, SiO
₂ 64.0%, Al ₂ O ₃ 3.5%, K ₂ O 13.0
%, Li ₂ O 3.5%, CaO 2.0%, MgO
1.0%, BaO 4.7%, SrO 7.0%, B ₂ O
₃ 0.5%, Sb ₂ O ₃ 0.3%, TiO ₂ 0.5%
The raw materials are weighed and mixed so that This raw material mixture is placed in a platinum crucible and heated and melted in an electric furnace.
After stirring and clarification, it is molded into a desired form. Note that when mass-produced in a tubular shape to produce the main tube, stem, etc. of a lighting lamp, it can be melted in a tank furnace and molded by a known tube-drawing method such as the Danner method without any problem. it can.

[0031]

EXAMPLES Further, the glass composition for illumination of the present invention will be described in detail with reference to Examples. Table 1 shows examples of the present invention and conventional examples. The composition in the table is expressed by mass%, and each sample was melted in a platinum crucible and cast into a mold in the same manner as in the above-mentioned embodiment to obtain samples for measuring various properties shown in Table 1.

Explaining the items in the table, the average coefficient of thermal expansion is 10 times the average coefficient of thermal expansion at 0 to 300 ° C.
^-7 K ^-1 and the electric resistance is the measured value at 100 ℃
It is shown by ogρ (Ω-cm). Also, Tg is a transition temperature,
The temperature at which the viscosity of glass η = 10 ^12.3 dPa · s, Ts
Is the softening temperature, which is the temperature at which the viscosity of the glass becomes η = 10 ^6.65 dPa · s.

The weathering resistance is determined by cutting each sample glass into a plate shape and optically polishing the sample so that the plate surface has a thickness of 1 mm. It was stored in a constant temperature and constant humidity chamber kept at 95% and compared with the transmittance after holding for 500 hours, which was shown as weather resistance.

Although the solarization resistance is not shown in the table, each glass sample was cut into a plate shape and the wall thickness was 1 m.
After performing double-sided optical polishing at m, the polished surface was placed 1 m from the mercury lamp (H-400P) with the polished surface facing the light source, and ultraviolet rays were irradiated to perform a solarization acceleration test. The evaluation was performed by comparing the transmittance at 400 nm after 300 hours of ultraviolet irradiation from the initial state. As a result, in all the glasses of the examples according to the present invention, the range of decrease in transmittance was within 1%, indicating good solarization resistance.

The UV cut property is 296 nm, 297 nm, 313n of the ultraviolet rays generated when the lamp is turned on.
At each wavelength of m and 334 nm, evaluation was made based on the initial transmittance of lead glass that has conventionally satisfied the ultraviolet emission standard. However, in the glasses of the examples according to the present invention, the transmittance at each wavelength is lead. It was equal to or lower than that of glass, and had sufficient UV cut characteristics required for fluorescent lamps.

[0036]

【table 1】

[0037]

【table 1】

As is apparent from Table 1, No. 1 which is an embodiment of the present invention. The glasses 1 to 13 have an average coefficient of thermal expansion almost equal to that of soda lime glass or lead-based glass generally used for electric bulbs and fluorescent lamps, and can be well welded to these glass parts. The electric resistance is also high enough. Further, devitrification was not observed in the glass of the example of the present invention through the steps such as melting and casting.

Regarding the weathering, although it can be said that the occurrence of weathering is completely absent in the examples of the present invention, even if it occurs, the degree thereof is mild as compared with the comparative examples described as the conventional examples of soda lime glass and lead-free glass. And
A clear improvement was seen.

In each of the above examples, Na was used._TwoIncluding O
It ’s not good, but Na_TwoO is glass even if added in small amounts
Has the effect of lowering the viscosity of, and improving the meltability and heat processability.
Therefore, there is a well-known soda lime glass and lead-free lighting.
A sufficiently small amount compared to the amount contained in glass, for example 1
Even if less than%, the effect is exhibited. Therefore, especially melt
For example, if you want to lower the temperature or make heat processing easier.
To meet the demand, a very small amount of Na_TwoConsider adding O
Yes. Even in that case, compared to conventional glass, Na _TwoIncluding O
The amount of mercury used in the lamp can be reduced by the amount
It As a result, the amount of mercury added to the fluorescent lamp is
Uses a conventional glass lamp vessel containing thorium
Needless to say, the number of lamps can be reduced more than the lamps.

[0041]

INDUSTRIAL APPLICABILITY As described above, the glass of the present invention contains substantially no lead, but is as excellent in electrical conductivity as the soda-lime glass or lead-based glass used for conventional lighting. It has insulating properties and heat processability, and does not cause environmental problems due to lead. Further, since it does not substantially contain a sodium component, reduction of the amount of mercury enclosed when used in a fluorescent lamp can be expected, and luminous flux deterioration due to amalgam formation or reaction with a phosphor can be prevented. Further, since it is also excellent in weathering resistance, it has an advantage that it can provide a constant quality with little luminous flux deterioration even during long-term storage or use of a lamp.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4G062 AA03 BB01 DA06 DB03 DC02                       DC03 DD01 DE01 DF01 EA03                       EB01 EC03 EC04 ED01 ED02                       ED03 EE01 EE02 EE03 EF03                       EG03 FA01 FA10 FB01 FB02                       FB03 FC01 FD01 FE01 FF01                       FG01 FH01 FJ01 FK01 FL01                       FL02 GA01 GA10 GB01 GC01                       GD01 GE01 HH01 HH03 HH05                       HH07 HH09 HH11 HH13 HH15                       HH17 HH20 JJ01 JJ03 JJ04                       JJ05 JJ07 JJ10 KK01 KK03                       KK05 KK07 KK10 MM24 NN13                       NN29 NN34

Claims (5)

[Claims] 1. A mass percentage of SiO ₂ 60-70%,
Al ₂ O ₃ 2-5%, Li ₂ O 1-5%, K ₂ O 9-
15%, Li ₂ O + K ₂ O 10-18%, CaO 0-
6%, MgO 0-3%, BaO 1-6%, SrO 1
~ 8%, MgO + CaO + BaO + SrO 8-20
%, B ₂ O ₃ 0.5 to 3%, Sb ₂ O ₃ 0 to 1%, Ti
A glass composition for lighting comprising O ₂ 0 to 3% and CeO ₂ 0 to 1%. 2. The glass composition for lighting according to claim 1, which is substantially free of sodium. _3. The glass composition for lighting according to claim 1, wherein the total amount of TiO ₂ + Al ₂ O ₃ is 2.5 to 6% in terms of mass percentage. 4. The glass composition for lighting according to claim 1, wherein the total amount of TiO ₂ + CeO ₂ is 0.05 to 3% in terms of mass percentage. 5. The TiO ₂ content is 0.0 in terms of mass percentage.
It is 5 to 3%, The glass composition for lighting of Claim 3 or 4 characterized by the above-mentioned.