JP2001287929A - Glass for stem and exhaust tube of hid lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lead-free glass excellent in electrical insulating properties and suitable as a stem or an exhaust tube of a high intensity discharge(HID) lamp. SOLUTION: This glass for the stem and exhaust tube pipe of the HID lamp is characterized as comprising a lead-free glass having an SiO2-B2O3-Al2O3-RO-R '2O-based composition and <=0.6 mass ratio of Na2O/(Na2O+K2O) and having >=108.7 Ω.cm volume resistivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an HID (high intensity)
ty discharge) relates to the stem of the lamp and the glass for the exhaust pipe.

[0002]

2. Description of the Related Art HID lamps are a general term for high-intensity discharge lamps such as mercury lamps, metal halide lamps and high-pressure sodium lamps. The general structure of an HID lamp is
It has a double structure in which a bulb (outer bulb) made of borosilicate glass surrounds an arc tube made of quartz glass or alumina. Further, the outer valve is provided with a stem and an exhaust pipe sealed with a tungsten lead wire for supplying power. For this stem portion, glass having a high volume resistivity is required in order to ensure electrical insulation between the lead wires sealed at a distance of several mm to several cm. Therefore, in this stem and exhaust pipe, P
By containing about 6% by mass of bO, the volume resistivity becomes 2
Borosilicate glass having a high insulating property of about ^108.8 Ω · cm at 50 ° C. is used. In addition, since borosilicate glass contains PbO, the glass has excellent melting properties and moldability.

[0003]

With the recent increase in environmental awareness, it has been required to reduce harmful components in glass. PbO is not contained in glass used for stems and exhaust pipes of HID lamps. Is required.

However, among the conventional glasses which can be sealed with tungsten, those which do not contain PbO have a low insulating property of about 10 ^8.5 Ω · cm at 250 ° C. For this reason, the insulation is insufficient for high output or small HID lamp stems and exhaust pipe applications. In such a conventional glass having a low electric insulating property, a current leak occurs to generate heat, and in the worst case, the glass may be melted and the lamp function may be completely lost.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a lead-free glass having excellent electrical insulation properties and suitable as a stem or an exhaust pipe of an HID lamp.

[0006]

According to the present invention, there is provided an HID lamp comprising:
The stem and the glass for the exhaust pipe are made of SiO_Two-B_TwoO_Three-A
l_TwoO_Three-RO-R '_TwoO-based composition and Na_TwoO /
(Na_TwoO + K_TwoO) Lead-free glass with a mass ratio of 0.6 or less
Having a volume resistivity of 10 at 250 ° C. ^8.7Ω
cm or more.

[0007]

The stem and the glass for the exhaust pipe of the present invention are made of SiO.
_It is made of glass having a composition of _2- B ₂ O ₃ —Al ₂ O ₃ —RO—R ′ ₂ O system. In particular, Na ₂ O and K ₂ O are mixed in a mass ratio of N.
It is characterized in that a ₂ O / (Na ₂ O + K ₂ O) is adjusted to be 0.6 or less. When this value is 0.6 or less, the volume resistivity at 250 ° C. becomes ^108.7 Ω · cm or more, and high electrical insulation required for a stem of an HID lamp or glass for an exhaust pipe can be obtained. If this value exceeds 0.6, the electrical insulation becomes insufficient, and current leakage occurs to easily generate heat.

In the present invention, SiO ₂ and Al ₂ O
₃ and Al ₂ O ₃ / (SiO ₂ + Al ₂ O ₃ ) in a mass ratio of 0.3.
It is preferable to adjust so as to be in the range of 032 to 0.055. The reason is that tungsten seal glass containing no PbO generally has a high devitrification property, so that the glass is liable to be deteriorated at the time of manufacture, and it is difficult to manufacture stably in large quantities at low cost. If it is above, the liquidus viscosity becomes 10 ⁵ dPa · s or more, the devitrification property is improved, and stable production at an industrial level becomes easy. However, if it exceeds 0.055, glass melting becomes difficult.

The stem and the glass for an exhaust pipe of the present invention are, specifically, 65 to 76% of SiO ₂ and B ₂ O _{3 by} mass percentage.
_{10~25%, Al 2 O 3 2~6} %, MgO + CaO
+ SrO + BaO + ZnO 0.5-5.8%, Li _{2
O + Na 2 O + K 2} O 3~8%, has a composition of _{ZrO 2 0~2%, Na 2 O} / (Na 2 O + K 2 O) is preferably made of 0.6 following lead-free glass. The reasons for limiting the content of each component as described above are as follows.

[0010] SiO ₂ is a main component necessary for constituting the glass skeleton, and its content is 65 to 76%, preferably 68 to 74%. If the content of SiO ₂ is more than 76%, the devitrification deteriorates rapidly. In addition, it takes a long time to melt the silica raw material, and it is not suitable for mass production. In addition, the coefficient of thermal expansion of the glass becomes too small to match that of tungsten, making sealing difficult. On the other hand, if the content is less than 65%, the chemical durability is deteriorated, so that the glass surface is burnt or the like, and the reliability of the HID lamp is reduced. Also, the coefficient of thermal expansion of glass becomes too large to match that of tungsten, making sealing difficult.

B ₂ O ₃ is a component necessary for improving the melting property, adjusting the viscosity, and improving the chemical durability, and its content is 10 to 25%, preferably 13 to 19%. .
If B ₂ O ₃ is more than 25%, there is a problem that evaporation from the glass melt increases to make it impossible to obtain a homogeneous glass, and evaporation occurs during thermal processing in the lamp manufacturing process to contaminate the members. Also, the chemical durability of the glass deteriorates. On the other hand, if it is less than 10%, the viscosity becomes too high and melting and processing become difficult.

Al ₂ O ₃ is a component that greatly improves the devitrification of glass, and its content is 2 to 6%, preferably 2.3 to 4.5%. If the content of Al ₂ O ₃ is more than 6%, the viscosity of the glass melt becomes too high, so that glass without bubbles or stria cannot be obtained. On the other hand, if it is less than 2%, the above-mentioned effects cannot be obtained, and it becomes difficult to produce a homogeneous glass and to perform stable molding.

MgO, CaO, SrO, BaO, and Z
nO has the effect of lowering the viscosity of the glass melt to facilitate melting and improving the chemical durability of the glass, and its content is 0.5 to 5.8% in total, preferably 1 to 4
%. If the total amount of these components is more than 5.8%, devitrification and phase separation occur in the glass, and a glass having high homogeneity and transparency cannot be obtained. On the other hand, if it is less than 0.5%, the meltability and the chemical durability decrease.

Among the above components, BaO is particularly effective in lowering the viscosity and enhancing the meltability.
O has a smaller effect of causing devitrification and phase separation in glass than O. Therefore, in the present invention, 0.1 to 4%, particularly 0.5 to 3%.
%. If the content of BaO is more than 4%, devitrification occurs, and if the content is less than 0.1%, the above effects cannot be obtained. Also, MgO, CaO, SrO, and Z
The content of nO is 0 to 3% of MgO (particularly 0 to 1.5%).
%), CaO 0-3% (especially 0-1.5%), SrO
It is preferably 0 to 5% (particularly 0 to 2%) and ZnO 0 to 5% (particularly 0 to 2%). If the content of each component exceeds the above range, devitrification and phase separation tend to occur.

Li ₂ O, Na which is an alkali metal oxide
₂ O and K ₂ O are components added for facilitating melting of the glass and controlling the coefficient of thermal expansion and viscosity, and the total content thereof is 3 to 8%, preferably 4 to 7%. is there. If the total amount of these components is more than 8%, the coefficient of thermal expansion becomes too high, so that it is not suitable for a tungsten seal and causes a significant decrease in chemical durability. On the other hand, if it is less than 3%, vitrification becomes difficult, and the coefficient of thermal expansion becomes too small.

The contents of Li ₂ O, Na ₂ O, and K ₂ O are as follows: Li ₂ O: 0 to 3% (particularly, 0.1 to ₂ %);
0-5% (particularly 0.5~3%), K ₂ O 0.5~7
% (Especially 1 to 6%). Note that Li ₂
If O exceeds 3%, phase separation is likely to occur. Na ₂ O
Exceeds 5%, the coefficient of thermal expansion becomes too large. Also, the weather resistance is deteriorated. If K ₂ O exceeds 7%, the coefficient of thermal expansion tends to be large, and if it is less than 0.5%, the coefficient of thermal expansion is small and it is difficult to vitrify.

ZrO ₂ is a component for improving weather resistance, and its content is 0 to 2%, preferably 0 to 1%. When ZrO ₂ exceeds 2%, devitrification deteriorates.

Further, in addition to the above-mentioned components, for the purpose of adjusting the viscosity of the glass and improving the weather resistance, melting property, clarity, etc., P
Components such as ₂ O ₅ , SO ₃ , F, and Cl can be added in appropriate amounts.

Further, based on the glass of the present invention, T
iO ₂ and Sb ₂ O ₃ alone or in a combined amount of 0.05 to
By adding 10%, high ultraviolet solarization resistance can be imparted to the glass. Furthermore, it is possible to enhance the absorbing wavelengths in the ultraviolet range ultraviolet shielding property of the Fe ₂ O ₃ and CeO ₂ alone or in total by the inclusion 0.01 to 4%. Thus, the glass of the present invention can be used for an outer bulb of a HID lamp.

The glass of the present invention having the above composition has a composition of 25
The volume resistivity at 0 ° C. is 10 ^8.7 Ω · cm or more, the coefficient of thermal expansion in the temperature range of 30 to 380 ° C. is 34 to 43 × 10 ⁻⁷ / ° C., and the liquidus linear viscosity is 10 ^5.0 d.
It has a property of Pa · s or more. For this reason, it has a thermal expansion coefficient suitable for sealing with tungsten metal, and has excellent devitrification and electrical insulation properties, and thus is most suitable as a glass for an HID lamp stem or an exhaust pipe.

[0021]

Next, the stem of the HID lamp and the glass for an exhaust pipe of the present invention will be described based on examples.

Tables 1 to 4 show examples of the present invention (sample No. 1).
19) and Table 5 show comparative examples (sample Nos. 20 and 21). The sample No. Reference numeral 20 denotes an example of a conventional lead-free tungsten seal glass, which was originally developed for a xenon flash lamp. In addition, No. Reference numeral 21 denotes a conventional lead-containing HID lamp stem and exhaust pipe glass.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

[Table 4]

[0027]

[Table 5]

No. shown in the table. Each of samples 1 to 21 was prepared as follows.

First, a glass raw material was prepared so as to have the composition shown in the table, and then melted at 1550 ° C. for 8 hours using a platinum crucible. After melting, the melt was shaped and processed into a predetermined shape to produce each glass sample.

Next, for each sample, the coefficient of linear expansion, the temperature and viscosity of the liquidus line, and the volume resistivity were measured. The results are shown in Tables 6 to 10. The liquidus viscosity and volume resistivity are as follows:
Shown as logarithmic values.

[0031]

[Table 6]

[0032]

[Table 7]

[0033]

[Table 8]

[0034]

[Table 9]

[0035]

[Table 10]

As is clear from the table, the No. 1 of the embodiment of the present invention. Each of the samples 1 to 19 had a linear expansion coefficient of 35.1.
~40.5 × 10 ^-7 / ℃, liquidus viscosity of 10 ^5.0 dPa
S or more, the volume resistivity is 10 ^8.7 Ω · cm or more,
It had characteristics equivalent to those of a conventional glass containing lead (Sample No. 21).

On the other hand, the comparative example No. Sample No. 20 had a low volume resistivity of 10 ^8.5 Ω · cm because the value of Na ₂ O / (Na ₂ O + K ₂ O) was larger than 0.6.

The coefficient of linear expansion in the table is obtained by measuring the average coefficient of linear expansion in a temperature range of 30 to 380 ° C. with a self-recording differential thermal dilatometer after processing a glass into a cylinder having a diameter of about 3 mm and a length of about 50 mm. It was done.

The temperature and viscosity of the liquidus were determined as follows. First, glass pulverized to a particle size of about 0.1 mm was put in a boat-shaped platinum container, kept in a temperature gradient furnace for 24 hours, and then taken out. This sample is observed with a microscope to measure the temperature at which the initial phase of the crystal comes out (liquidus temperature). Then, from the relationship between the temperature and the viscosity of the glass measured in advance, the viscosity corresponding to the temperature of the initial phase is determined. (Liquidus viscosity) was determined.

The volume resistivity was measured at a temperature of 250 ° C. by a method according to ASTM C-657. H
When the ID lamp is turned on, the temperature of the stem where the lead wire is sealed may exceed 200 ° C., and in order to prevent dielectric breakdown, the volume resistivity should be 10 ° C. at 250 ° C.
^8.7 Ω · cm or more is required.

[0041]

As described above, the glass of the present invention is made of PbO
Although it does not contain any of them, it has high electrical insulation properties and is therefore suitable as a glass material for stems of HID lamps or for exhaust pipes.

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Claims (3)

[Claims] 1. The method according to claim 1, wherein the SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —RO (R
Has Mg, Ca, Sr, Ba and one or more selected from _{Zn) -R '2 O (R} ' is Li, the composition of one or more) system selected from Na and K, and Na ₂ O / (Na ₂ O +
K ₂ O) is made of a lead-free glass having a mass ratio of 0.6 or less,
A HID lamp stem and an exhaust pipe glass having a volume resistivity at 250 ° C. of 10 ^8.7 Ω · cm or more. 2. The glass for a stem and an exhaust pipe of an HID lamp according to claim 1, wherein the mass ratio of Al ₂ O ₃ / (SiO ₂ + Al ₂ O ₃ ) is 0.032 to 0.055. 3. The composition according to claim _2, wherein the mass percentage is SiO ₂ 65-76.
_{%, B 2 O 3 10~25%} , Al 2 O 3 2~6%, Mg
O + CaO + SrO + BaO + ZnO 0.5 to 5.8
_{%, Li 2 O + Na 2} O + K 2 O 3~8%, ZrO 2 0
Has a 2% _{composition, Na 2 O / (Na 2} O + K 2 O) is according to claim 1 or 2 of the HID lamp of the stem, characterized in that it consists of 0.6 following lead-free glass, and glass exhaust pipe .