JP2009067676A - Lighting glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting glass which is lead-free, has a sufficient electrical insulation property, is excellent in thermal processability and is suitable for use in a stem tube and the like. <P>SOLUTION: The lighting glass is substantially free of lead as a glass composition and comprises, by mass, 65-75% SiO<SB>2</SB>, 0.5-5% Al<SB>2</SB>O<SB>3</SB>, 0-2% B<SB>2</SB>O<SB>3</SB>, 0-4% CaO, 0-4% MgO, 0-4% SrO, 5-12% BaO, 0-9% ZnO, 6-15% BaO+ZnO, 8-16% CaO+MgO+SrO+BaO+ZnO, SrO/(BaO+ZnO)<0.3, 3-12% Na<SB>2</SB>O, 3.5-9% K<SB>2</SB>O, 0.5-5% Li<SB>2</SB>O, 10-18% Na<SB>2</SB>O+K<SB>2</SB>O+Li<SB>2</SB>O, and is used in the stem tube. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an illumination glass that is substantially free of lead and is used for stem tubes and the like.

  The stem part into which the electrode wire of a fluorescent lamp or incandescent bulb is inserted and sealed must have sufficient high electrical insulation so that current does not leak, and the electrode wire sealing part can be processed and sealed at a low temperature. Thus, glass containing 20 to 30% by mass of lead has been used. However, because of the harmfulness of lead, glass compositions containing no lead are required and developed. As a glass for lighting which does not contain lead, there is one described in Patent Document 1, for example. The glass described in this document is a lead-free glass containing 7 to 11% of BaO and having an electrical insulation equivalent to that of conventional lead glass, and can be used for stem applications and fluorescent lamp bulbs. This type of lead-free glass is excellent in workability, although not as much as lead glass.

  In recent years, compact fluorescent lamps are becoming widespread. This fluorescent lamp has a complicated bulb shape such that the bulb is bent or connected, and the bulb material is required to have easy processing characteristics. For this reason, lead glass having excellent workability has been used in the past, but there is a demand for lead-free glass.

Therefore, lead-free glass represented by Patent Document 1 has begun to be used for compact fluorescent bulbs as an alternative to lead glass. Moreover, it has been clarified that the efficiency of the light output of the fluorescent lamp is improved because of the lead-free glass. This is because lead-free glass has a lower refractive index than lead glass, and reflection of light on the glass surface is small. This is because visible light is generated in the fluorescent substance inside the fluorescent lamp, but the amount of light passing through the bulb increases because the reflection of the glass constituting the bulb is small. Under these circumstances, the demand for lead-free glass is increasing even in compact fluorescent lamp bulb applications.
JP-A-6-206737

  In general lamp production lines such as fluorescent lamps and light bulbs, the speed of the line is increased by pursuing productivity improvement, but this makes the stem processing of lead-free glass difficult. Therefore, there is a growing demand for further improvement of thermal workability for lead-free glass.

  Further, from the viewpoint of energy saving, there is a demand for a compact and high output lamp as a compact fluorescent lamp. For this reason, the shape of the valve is further complicated, making it difficult to process. In addition, as the diameter of the bulb has been reduced, a simplified structure has been adopted in which the stem is not used in the sealing portion, but instead the end portion of the bulb is heated and softened and crushed to directly seal the electrode wire. It has begun to be adopted. For this reason, it is necessary to further improve the heat workability in valve applications. In addition, in the case of this structure, in order to directly seal the electrode wire, high electrical resistance is required as in the conventional stem tube.

  An object of the present invention is to provide a lighting glass having sufficient electrical insulation and excellent heat workability while being lead-free glass so that it can be used in these applications.

The glass for illumination of the present invention contains substantially no lead as a glass composition, and is in a mass percentage of SiO ₂ 65-75%, Al ₂ O ₃ 0.5-5%, B ₂ O ₃ 0-2. %, CaO 0-4%, MgO 0-4%, SrO 0-4%, BaO 5-12%, ZnO 0-9%, BaO + ZnO 6-15%, CaO + MgO + SrO + BaO + ZnO 8-16%, SrO / (BaO + ZnO) < 0.3, Na ₂ O 3-12%, K ₂ O 3.5-9%, Li ₂ O 0.5-5%, Na ₂ O + K ₂ O + Li ₂ O 10-18%, and in the stem tube It is characterized by using.

  The lamp stem is manufactured in the following manner. First, after heat-softening one end of the long tube for the stem tube directly with a burner, the tube is expanded from the inside of the heating part with a jig made of carbon or heat-resistant steel, made into a flared shape, and then a predetermined length Disconnect. Thereafter, the exhaust pipe is welded to the cut flared stem tube by thermal processing of the burner, the electrode wire is sealed, and the stem is made. Thus, many thermal processing steps are incorporated in the processing of the stem.

  The thermal processing step frequently used in the stem production process is performed under an appropriate viscosity condition between the softening point of the glass and the working temperature. Outside this temperature range, problems such as failure to weld or seal, or deformation before welding occur. For this reason, the larger the difference between the softening point of the glass and the working temperature, the smaller the change in viscosity with respect to the temperature change in the working region, so that the allowable amount with respect to the set working temperature increases and the glass becomes easy to work. This point is not unique to the manufacture of the stem, but is also common to other thermal processing processes such as processing of the bulb of a compact fluorescent lamp and direct sealing of the electrode wire by the bulb. .

  Therefore, in order to obtain a glass having excellent heat workability, it is important to design the glass so that the temperature difference between the softening point of the glass and the working temperature is large. And as a result of conducting various experiments paying attention to divalent metal oxide components (alkaline earth metal oxide and ZnO), the present inventors obtained useful knowledge given to the workability of glass. The contents are as follows.

  Alkaline earth metal oxides such as CaO, MgO, SrO, BaO and ZnO are contained in order to obtain easy workability and high electrical resistance, and are essential components for obtaining workability close to that of lead-containing glass. If the total amount is less than 8%, there is no effect, and if it exceeds 16%, the glass tube tends to be devitrified during molding.

  Moreover, workability is further improved by optimizing the content and ratio of specific components among these divalent metal oxides. Specifically, the total content of BaO and ZnO is 6% or more, and the ratio of the content of SrO to the total content of BaO and ZnO (SrO / (BaO + ZnO)) is less than 0.3 (including 0) In some cases, the temperature difference between the working temperatures from the softening point of the glass significantly widens, giving the glass sufficient workability. In addition, when the total amount of BaO and ZnO exceeds 15%, devitrification may occur at the time of glass tube forming.

  The reason why the individual contents of the divalent metal oxide are limited as described above is as follows.

CaO and MgO give easy processability and high electrical resistance to glass, but if each exceeds 4%, high light output when used as a bulb due to a decrease in transmittance in the visible region, particularly near the near ultraviolet, from the viewpoint of transmittance characteristics. It becomes difficult to obtain a lamp. The preferred range of CaO and MgO is 0 to 3% each. SrO gives easy processability and high electrical resistance to glass, but if it exceeds 4%, it is visible from the viewpoint of transmittance characteristics, particularly in the vicinity of near ultraviolet. The reduction in the rate makes it difficult to obtain a high light output lamp when used as a bulb. Compared with other divalent metal oxides, since the effect of widening the temperature difference between the working temperatures from the softening point of the glass is small, the preferred range is 0 to 3%, and the content is kept to a minimum as much as possible. Is desirable.

  BaO has a large effect of imparting easy processability and high electrical resistance to glass, and is an essential component for obtaining processability and electrical properties close to those of lead-containing glass. Further, from the viewpoint of transmittance characteristics, it is less likely to cause a decrease in transmittance in the visible region, particularly in the vicinity of near ultraviolet, as compared with other alkaline earth metal oxides. If BaO is less than 5%, the effect cannot be obtained. Also, if other alkaline earth metal oxides such as CaO and MgO are added in order to obtain the same workability and electric resistance, the transmittance characteristics deteriorate, and it is difficult to obtain a lamp with high light output when used as a bulb. become. On the other hand, when the content of BaO exceeds 12%, devitrification is likely to occur during glass tube forming. In addition, the preferable range of BaO is 5 to 10%.

  ZnO has the effect of improving weather resistance. Moreover, like BaO, the glass is provided with easy processability and high electrical resistance similar to those of lead-containing glass. Further, if the content is 9% or less, it is difficult to cause a problem of a decrease in transmittance in the visible region, particularly in the vicinity of the near ultraviolet. In addition, the preferable range of ZnO is 0 to 7%.

  The reason why the range of the other composition of the present invention is limited is as follows.

SiO ₂ is a component that forms a glass skeleton. If the SiO ₂ content is less than 65%, the generation of the glass skeleton is insufficient, and the mechanical strength, chemical durability, and volume resistivity are lowered. If the SiO ₂ content is more than 75%, the viscosity of the glass increases and melt molding becomes difficult. Incidentally preferred range of SiO ₂ is 67 to 74%.

Al ₂ O _{3 is} also a skeleton-forming component and has the effect of improving chemical durability and suppressing devitrification during glass forming. If Al ₂ O ₃ is less than 0.5%, the effect is not obtained, and if it is more than 5%, melting or molding becomes difficult. A preferred range for Al ₂ O ₃ is 0.5-4%.

B ₂ O ₃ has the effect of improving chemical durability and lowering high temperature viscosity. However, since B ₂ O ₃ is an environmentally hazardous substance, it is desirable not to use it unless it is unavoidable. When B ₂ O ₃ is more than 2%, the volatilization at the time of melting increases, reacting with the refractory constituting the melting furnace, and easily damaging the melting furnace.

Alkali metal oxides such as Na ₂ O, K ₂ O, and Li ₂ O are essential components for adjusting the thermal expansion coefficient and reducing the viscosity of the glass to improve the workability. By causing Na ₂ O, K ₂ O and Li ₂ O to coexist in a specific ratio, an effect of improving chemical durability and electrical insulation called an alkali mixing effect can be obtained. In addition, Li ₂ O has a higher expansion adjustment function than other alkali metal components, and is effective when added in a small amount, and is an effective component for lowering the processing temperature because it lowers the viscosity.

When Na ₂ O is less than 3%, the effect is not obtained. When it exceeds 12%, the alkali mixing effect cannot be obtained, and the chemical durability and the electrical insulation are deteriorated.

When K ₂ O is less than 3.5%, the effect is not obtained, and when it exceeds 9%, the alkali mixing effect cannot be obtained, and the chemical durability and the electrical insulation are deteriorated.

When Li ₂ O is less than 0.5%, it is necessary to contain a large amount of Na ₂ O and K ₂ O to adjust the processing temperature and to achieve expansion consistency with the dumet electrode wire. It cannot be obtained, and chemical durability and electrical insulation are deteriorated. Conversely, if it exceeds 5%, only a small amount of Na ₂ O or K ₂ O can be contained, and the alkali mixing effect cannot be obtained.

Further, if the total amount of Na ₂ O, K ₂ O, and Li ₂ O is less than 10%, it is difficult to obtain expansion consistency with the dumet electrode wire when used as a stem tube or according to the usage. In addition, the viscosity of the glass increases, and the processability tends to deteriorate. On the other hand, if the total amount of the alkali metal oxide exceeds 18%, it is difficult to obtain expansion consistency with the dumet electrode wire when used for a stem tube application. In addition, the chemical durability is deteriorated, and when used as a bulb, it becomes easy to generate amalgam that causes a decrease in light output.

The _{Na 2 O, K 2 O,} Li 2 O _is, Na ₂ O: When configured in a ratio of 0.5~4%,: 3~10%, K 2 O: 4~7%, Li 2 O A higher alkali mixing effect can be obtained, and the electrical insulation required for the stem tube in which the electrode wire is enclosed and the type of valve that directly seals the electrode wire can be sufficiently satisfied.

CeO ₂ is a useful component when used as a bulb because it imparts an ultraviolet shielding effect to glass and has the effect of reducing the decrease in transmittance due to ultraviolet irradiation. Also functions as a fining agent. If the CeO ₂ content is more than 1.2%, the glass tends to be colored yellow, making it difficult to obtain a lamp with high light output. It is preferable to keep the content at 0.9% or less.

Sb ₂ O ₃ is a useful component as a fining agent, but in the presence of CeO ₂ , glass tends to be colored yellow, so it is better not to coexist in bulb applications. Moreover, when one end of a valve is heat-processed and sealed together with an electrode wire and an exhaust pipe like a wedge sphere for automobiles, the content is 0 to 1%, particularly 0 to 0.2%, because it is blackened by heat processing. Preferably, it is more preferable not to contain substantially.

In addition to the above components, various components can be added. For example, Cl or SO ₃ can be used as a fining agent. For bulb use, it is possible to add a component having an effect of preventing ultraviolet coloring such as TiO ₂ and ZrO ₂ . Although Fe ₂ O ₃ is often included as an impurity, Fe is a colored ion on the other hand, which gives an ultraviolet shielding effect to glass, and also causes a decrease in transmittance in the visible range. It is important to limit it to 0.8% or less. Furthermore, for environmental reasons, the use of PbO or As ₂ O ₃ should be avoided and should be substantially free of inclusion.

  Moreover, as for the glass for illumination of this invention, it is desirable that the infrared transmittance coefficient (X) represented by the following formula is 0.1 or more. This is due to the following reason.

X = (log ₁₀ a-log ₁₀ b) / t
a: Transmittance (%) of 3846 cm ⁻¹
b: Transmittance (%) of the minimum point near 3560 cm ⁻¹
t: Measurement sample thickness (mm)
That is, in order to obtain a fluorescent lamp with high light output, it is important that mercury that emits ultraviolet rays inside the fluorescent lamp is not consumed. The reason why mercury is consumed is that sodium contained in the glass of the fluorescent lamp bulb moves from the inside of the glass to the glass surface to generate mercury and amalgam. In the glass of the present invention, the movement of sodium is reduced by utilizing the alkali mixing effect to suppress the formation of amalgam. However, sodium is volatilized from the glass and taken into the inner surface of the bulb and the phosphor during the heat processing for bending or connecting the bulb during the fluorescent lamp manufacturing process. When a fluorescent lamp is turned on, this reacts instantly with evaporated mercury and produces amalgam. As a result, mercury is consumed and the light output of the lamp is reduced. Therefore, lowering the processing temperature and suppressing sodium volatilization during thermal processing are important in obtaining a lamp with high light output. In order to lower the processing temperature, it is necessary to lower the temperature of the glass processing region (from the softening point to the working temperature).

  Increasing the amount of moisture in the glass is effective as a means for reducing the temperature of the glass processing zone (from the softening point to the working temperature). In other words, the water in the glass has the function of lowering the temperature of the glass processing area without greatly changing the electrical resistance characteristics necessary for the lighting glass, thermal expansion matching with the jumet lead wire, and the like. . The infrared transmittance coefficient (X) described in the above equation is proportional to the amount of moisture in the glass. If this coefficient is 0.1 or more, the glass has sufficient moisture to obtain the above effect. Means that For the above reasons, it is preferable that the glass has more moisture, but if the infrared transmittance coefficient (X) exceeds 0.5, one end of the valve is heat-processed and sealed together with the electrode wire and the exhaust pipe like an automobile wedge sphere. When water is evaporated, water evaporates from the inside of the glass and a part of the water is adsorbed on the inner surface of the bulb, which may damage the tungsten filament when the lamp is turned on.

  The amount of moisture is adjusted by the moisture in the combustion gas when the glass is melted and the glass raw material (mixing ratio of boric acid and anhydrous borax). Moreover, when it cannot adjust with these, it can adjust by bubbling dry air or water vapor | steam at the time of glass melting.

  Next, a method for producing a stem tube or bulb such as a fluorescent lamp using the lighting glass of the present invention will be described. First, the raw materials are prepared so as to have the above composition, mixed, and then melted in a melting furnace. At this time, the amount of water in the glass is adjusted as necessary. Next, the molten glass is formed into a tubular shape by using a tube drawing method such as the Danner method, the down draw method, or the up draw method. Thereafter, the tubular glass is cut into a predetermined size and post-processed as necessary, whereby a stem tube and a valve can be obtained.

  By using the stem tube and the bulb thus obtained, a general fluorescent lamp, a light bulb, or a compact fluorescent lamp can be produced according to a conventional method.

  Hereinafter, the present invention will be described based on examples. Note that “ND” in each table indicates that the measurement has not been performed.

  Table 1 shows experimental examples (samples Nos. 1 and 2) in which the kind and content of alkaline earth oxides contained were changed, and the temperature difference between the softening point of the glass showing the workability of the glass and the working temperature was evaluated. Table 2 shows experimental examples (sample Nos. 3 to 5) in which the amount of water contained was changed and the processing temperature range (working temperature from the softening point of the glass) was evaluated.

  Each sample was prepared as follows.

First, glass raw materials were prepared so as to have the composition shown in the table. Furthermore, the prepared raw material was stirred for 10 minutes with a mortar-type crushing stirrer called “Laikai machine” to obtain a 300 g raw material batch. Next, the raw material batch was put into a crucible made of platinum rhodium alloy having a capacity of 300 cm ³ and melted at 1450 to 1500 ° C. for 4 hours in a box-type electric furnace. In addition, it stirred for a total of 3 times using the platinum stirring rod every 30 minutes after the melting start.

  In order to change the amount of water to be contained, a platinum rhodium pipe was inserted into the glass being melted in the crucible, water vapor was poured into the glass through this pipe, and water vapor bubbling was performed while adjusting the amount of water vapor to be poured. .

  Subsequently, the molten glass was poured onto a carbon molded plate, placed in a box-type Kanthal annealing furnace maintained at 560 ° C., and cooled at an average cooling rate of 4 ° C./min. Further, a sample was prepared from the annealed glass lump and used for evaluation. The results are shown in Tables 1 and 2.

  As is apparent from Table 1, it was found that when a part of BaO was replaced with SrO and the compositional composition was changed to SrO / (BaO + ZnO)> 0.3, the difference between the softening point of the glass and the working temperature was narrowed. .

  Further, from Table 2, it was found that the softening point of the glass greatly decreases as the value of the infrared transmittance coefficient (X) indicating the water content increases. At this time, the working temperature also decreased, but the degree was not as low as the softening point decreased, and as a result, it became clear that the temperature difference between the softening point of the glass and the working temperature widened.

The thermal expansion coefficient indicates an average linear thermal expansion coefficient at 30 to 380 ° C., and was measured using a dilatometer. The softening point is a temperature showing a viscosity of 10 ^7.6 dPa · s, and the working temperature is a temperature showing a viscosity of 10 ⁴ dPa · s, which were determined using the fiber pulling method and the platinum ball pulling method specified by ASTM, respectively. . The volume resistivity was measured based on ASTM C657-78, and the resistance value at 150 ° C. was expressed logarithmically. The alkali elution amount is measured based on JIS R-3502.

Infrared transmittance coefficient (X) is converted to 1 mm thickness by substituting transmittance a at 3846 cm ⁻¹ measured by an infrared spectrophotometer and transmittance b at a minimum point near 3560 cm ⁻¹ into the following formula. Asked. Here, t represents the thickness (mm) of the measured sample.

X = (log ₁₀ a-log ₁₀ b) / t
The transmittance at 400 nm is obtained by measuring a sample obtained by optically polishing both sides having a thickness of 1 mm with a spectrophotometer.

  Table 3 shows other examples (sample Nos. 6 to 9) of the present invention. Each sample was prepared and evaluated according to Example 1.

  According to Table 3, the sample No. It was confirmed that 6 to 9 had a wide processing temperature range and showed a sufficient volume resistivity.

  As described above, the lighting glass of the present invention has sufficient electrical insulation and good heat workability. For this reason, it can be used for a stem tube and can cope with the production line speed of general fluorescent lamps and light bulbs. In addition, when used as a compact fluorescent lamp, it is possible to deal with complicated processing for further compactness, and the electrode wire can be directly sealed. In addition, if the infrared transmittance coefficient (X) indicating the moisture content is adjusted to 0.1 or more, the processing temperature can be lowered, so that a lamp with low mercury consumption and high light output can be produced. It becomes possible. Therefore, it is suitable as a bulb material for stem tubes and compact fluorescent lamps.

In this specification, the bulb use of stem tubes and compact fluorescent lamps has been mainly described. However, the glass of the present invention is not limited to these, and other lamp uses (as backlights used in liquid crystal displays). The fluorescent material may be used for other lamp members (exhaust pipes, etc.) or fluorescent lamps and flat lamp glass, etc. It is also suitable for automobile spheres represented by wedge spheres, and it can be used for bulb materials such as orange direction indicator lamps and red stop lamps by adding colorants.

Claims (2)

As a glass composition, substantially containing no lead, by mass _{percentage, SiO 2 65~75%, Al 2} O 3 0.5~5%, B 2 O 3 0~2%, CaO 0~4%, MgO 0-4%, SrO 0-4%, BaO 5-12%, ZnO 0-9%, BaO + ZnO 6-15%, CaO + MgO + SrO + BaO + ZnO 8-16%, SrO / (BaO + ZnO) <0.3, Na ₂ O 3 -12%, K ₂ O 3.5-9%, Li ₂ O 0.5-5%, Na ₂ O + K ₂ O + Li ₂ O 10-18%, and used for a stem tube Glass. The glass for illumination according to claim 1, wherein the infrared transmittance coefficient (X) is 0.1 or more in the following formula.
X = (log ₁₀ a-log ₁₀ b) / t
a: Transmittance (%) of 3846 cm ⁻¹
b: Transmittance (%) of the minimum point near 3560 cm ⁻¹
t: Measurement sample thickness (mm)