JP4453305B2 - Fluorescent lamp outer tube and fluorescent lamp - Google Patents

Description

  The present invention relates to an outer tube for a fluorescent lamp, and more particularly to an outer tube for a small-diameter fluorescent lamp used as a backlight light source of a liquid crystal display element.

  Since the liquid crystal display element does not emit light, an illumination device such as a backlight is required. As the lighting device, the fluorescent lamp is placed directly under the liquid crystal panel, the reflector plate emits light to the panel side, and the diffuser plate makes the light uniform, and the fluorescent lamp is placed behind the liquid crystal panel. There is an edge type illuminating device that is installed on the side, guides light from the reflection plate to the light guide plate, and emits light to the liquid crystal panel side through the diffusion plate. The direct type liquid crystal display device is suitable for a large liquid crystal display panel such as a TV, and the edge type liquid crystal display device is widely used in personal computers (PCs) because it can be thinned.

  As a fluorescent lamp used as a light source, a cold cathode fluorescent lamp is used (for example, Patent Document 1). The cold cathode fluorescent lamp is manufactured using an electrode such as kovar, tungsten, molybdenum, sealing beads for sealing the electrode, and a borosilicate glass outer tube coated with a phosphor on the inner surface.

The light emission principle of the cold cathode lamp is the same as that of a general hot cathode lamp. Mercury gas enclosed by the discharge between the electrodes is excited and applied to the inner wall surface of the outer tube by ultraviolet rays emitted from the excited gas. The phosphor emits visible light.
JP-A-6-111784 Japanese Patent Laid-Open No. 2002-60245 JP 2002-68775 A

  The major difference between a cold cathode lamp and a hot-cathode lamp for general lighting is that the glass envelope is thin and thin and structurally weak in mechanical strength, so that the envelope is higher in strength. Is required. Unlike a hot cathode lamp, it does not burn out, but the brightness decreases with time. For this reason, the lifetime of the cold cathode lamp is represented by the time when it is half the initial luminous flux. The cause of the light beam deterioration is caused not only by the fluorescent lamp of the light source but also by the deterioration of the resin reflecting plate that efficiently reflects the light and the diffusion plate that diffuses the light. The deterioration of these resin materials is caused by ultraviolet rays generated inside the lamp leaking out of the tube.

Therefore, borosilicate glass having high mechanical strength is used for this type of lamp mantle. In order to prevent the leakage of ultraviolet rays to the outside of the tube, it has been studied to construct the outer tube with glass having ultraviolet shielding properties. For example, Patent Document 2 discloses a glass envelope for a fluorescent lamp using WO ₃ or Nb ₂ O ₅ and Patent Document 3 using TiO ₂ to provide ultraviolet shielding.

  However, the above-described conventional mantle tube has a strong ability to shield ultraviolet rays up to 254 nm generated inside the fluorescent lamp, but has no ability to absorb weak ultraviolet rays of 313 nm. For this reason, it is not a problem for PC applications with a relatively short life, but when long-term use is assumed, such as TV applications, a decrease in lamp performance due to deterioration of the resin material is negligible. It is gone.

  An object of the present invention is to provide an outer tube for a fluorescent lamp capable of shielding ultraviolet rays of 313 nm or less and a fluorescent lamp using the same.

The outer tube for the fluorescent lamp of the present invention is in mass percentage,
SiO ₂ 55~76%,
B ₂ O ₃ 6-25%,
Al ₂ O ₃ 0-10%,
Li ₂ O 0-10%,
Na ₂ O 0-10%,
K ₂ O 0-15%,
Li ₂ O + Na ₂ O + K ₂ O 3-20%,
MgO 0-8%,
CaO 0-8%,
SrO 0-15%,
BaO 0-15%,
ZnO 0-15%,
ZrO ₂ 0-9%,
Fe ₂ O ₃ 0.003~0.05%,
TiO ₂ 0-10%,
Cl ₂ 0-0.5%,
SO ₃ 0.005~1%
It is made of borosilicate glass containing colloidal particles.

  In the fluorescent lamp envelope of the present invention, the colloidal particles are ZnS colloids.

The fluorescent lamp outer tube of the present invention is characterized in that Fe ³⁺ / total Fe amount is 0.4 or less.

  The outer tube for a fluorescent lamp of the present invention is a thin tube having a diameter of 8 mm or less and a wall thickness of 0.6 mm or less.

  The fluorescent lamp of the present invention is manufactured using the above-described outer tube.

  The fluorescent lamp of the present invention is characterized in that the electrode is sealed with sealing beads made of the same material as the outer tube.

  The fluorescent lamp of the present invention is characterized in that the electrode is made of Kovar, molybdenum or tungsten.

  The fluorescent lamp of the present invention is used as a light source of an illumination device for a liquid crystal display element.

  The outer tube for the fluorescent lamp of the present invention has an ultraviolet shielding property at 313 nm. Moreover, it is possible to maintain high transparency over a long period of time by imparting sufficient ultraviolet solarization resistance. Therefore, it is suitable as an outer tube of a fluorescent lamp, particularly as an outer tube of a small-diameter fluorescent lamp used as a light source of a lighting device of a liquid crystal display element on the premise of long-term use such as TV use.

  Further, if the mantle tube made of the glass is used, a fluorescent lamp having high luminance and almost no luminance deterioration can be produced.

  The fluorescent lamp envelope of the present invention is made of borosilicate glass having high mechanical strength. Furthermore, colloidal particles are precipitated in the glass, and the presence of the colloidal particles can shield ultraviolet rays of 313 nm or less.

  It is considered that the content of colloidal particles is preferably about 0.01 to 0.4% by volume. When the tube thickness is thin (for example, 0.3 mm or less), it seems desirable to contain 0.1% by volume or more in order to obtain a sufficient ultraviolet shielding effect (transmittance of about 3% or less) at 313 nm. On the other hand, if the colloid amount is 0.4% by volume or less, it can be stably introduced into the glass. The size of the colloidal particles is preferably 1 to 400 nm. The content and size of the colloidal particles can be confirmed with a transmission electron microscope.

Although the kind of colloidal particle is not limited, it is preferable to select a ZnS colloid. The reason is that light is absorbed at a portion near the visible wavelength (from 380 nm). Further, a copper halide colloid may be deposited instead of the ZnS colloid. However, in this case, Cu is a coloring component that absorbs in the visible range, and advanced equipment is required to adjust the glass melting atmosphere, and in liquid crystal backlight light source applications where there is a strong demand for transparency, coloring is not possible in mass production. It is difficult to control. Therefore, it is advantageous to select a ZnS colloid from the viewpoint of preventing coloring. Of the various colloids, the FeS colloid causes coloration, so it is desirable to prevent it from precipitating. Therefore, attention should be paid to the content of Fe ₂ O ₃ .

  For example, in the case of a ZnS colloid, the amount and size of the colloidal particles are adjusted by controlling the contents of Zn and S, the melting atmosphere, heat treatment conditions, and the like. When the Zn component and the S component are introduced into the glass, the content can be easily adjusted by using a ZnS raw material.

  It is desired that the outer tube of a fluorescent lamp used as a light source of an illumination device such as a backlight satisfy the following characteristics in addition to the ultraviolet shielding property of 313 nm or less.

(1) Excellent ultraviolet solarization resistance.
The outer tube of the fluorescent lamp for the backlight is deteriorated in the quality of the liquid crystal display element when the glass is discolored by ultraviolet rays emitted from excited mercury gas or the like (so-called ultraviolet solarization). Leads to.

(2) Being transparent glass.
In TV applications, light emitted from lamps is reflected by the lamps to increase the optical path length. Therefore, if the glass is slightly colored, the color is emphasized and the liquid crystal display device becomes dark.

(3) Good dimensional accuracy.
If the dimensional accuracy is poor, the phosphor cannot be uniformly applied, resulting in uneven brightness. In addition, in an optical system composed of a fluorescent lamp, a light guide plate, and a reflection plate, it cannot be assembled according to the design dimensions, which causes a decrease in luminance or luminance unevenness of the backlight unit or the front light unit itself.

(4) There are very few bubbles.
If there is a bubble in the tube glass, it will be stretched into a thin bubble. When such a bubble is present on the inner surface side of the tube and a part of the bubble is open to the inner surface of the tube, when the cut surface of the tube comes on such an elongated bubble, the cut surface of the tube and the inner surface of the tube It is easy to become a hole that communicates. Since this hole is not blocked during processing of the tube glass, the outside air slowly leaks into the fluorescent lamp tube, causing a phenomenon that electrons do not fly in the tube and the fluorescent lamp does not emit light. In recent years, the glass wall thickness has become thinner due to the thin tube, and if bubbles are present, the possibility of bubbles opening on the inner surface of the tube is increasing. For this reason, the fine tube requires a bubble quality higher than that of conventional glass.

(5) The coefficient of thermal expansion is compatible with the electrode material.
Usually, the sealing bead for sealing the electrode (introduced metal) is made of the same material as the outer tube. Therefore, the outer tube is made of Kovar (thermal expansion coefficient 58 × 10 ⁻⁷ / ° C.), molybdenum (thermal expansion coefficient 52 × 10 ⁻⁷ / ° C.), tungsten (thermal expansion coefficient 45 × 10 ⁻⁷ / ° C.), which are electrode materials. It is necessary to have a coefficient of thermal expansion compatible with the above.

(6) Outgassing is less likely to occur during use of the fluorescent lamp.
If gas is released from the mantle during use, the luminous efficiency of the lamp deteriorates because the ultraviolet emission of Hg is inhibited.

As a glass capable of producing an outer tube satisfying the above various required characteristics, SiO ₂ 55 to 76%, B ₂ O ₃ 6 to 25%, Al ₂ O ₃ 0 to 10%, Li ₂ O 0 to 0 by mass percentage. _{10%, Na 2 O 0~10%} , K 2 O 0~15%, Li 2 O + Na 2 O + K 2 O 3~20%, 0~8% MgO, CaO 0~8%, SrO 0~15%, BaO _{0~15%, 0~15% ZnO, ZrO} 2 0~9%, Fe 2 O 3 0.003~0.05%, TiO 2 0~10%, Cl 2 0~0.5%, SO 3 0 Glass containing 0.005 to 1% is mentioned.

  The reason why the content of each component is limited as described above is as follows.

SiO ₂ is a main component necessary for constituting a glass skeleton, and its content is 55 to 76%, preferably 60 to 73%. More preferably, it is 60 to 67%. If the SiO ₂ content is 76% or less, it does not take a long time to melt the silica raw material, and if it is 73% or less, SiO ₂ crystals hardly occur in the glass, and the viscosity homogeneity is partially lost. The resulting deterioration in dimensional accuracy can be prevented. If it is desired to lower B ₂ O ₃ for the purpose of stabilizing the colloid in the glass, it is desirable to make it 67% or less in order to soften the glass viscosity. On the other hand, if the SiO ₂ content is 55% or more, sufficient chemical durability is obtained, and storage in a normal environment is not hindered. Further, if it is 60% or more, a phenomenon in which a thin film-like hydroxide is generated on the glass surface, that is, a decrease in transmittance due to so-called burns is less likely to occur, which is advantageous in maintaining the luminance of the fluorescent lamp.

B ₂ O ₃ is effective in improving the meltability, lowering the thermal expansion coefficient, adjusting the viscosity, and improving the chemical durability. On the other hand, B ₂ O ₃ facilitates phase separation of the glass and makes the glass opaque. Its content is 6 to 25%, preferably 6 to 16%, more preferably 10 to 15%. When B ₂ O ₃ is 25% or less, a homogeneous glass with little evaporation from the glass melt can be obtained. Further, if it is 16% or less, the glass component is less evaporated even during heat processing during the lamp manufacturing process, and the processing becomes easy. If it is less than 15%, phase separation does not occur even when a large amount of ZnS colloid is generated. . On the other hand, if B ₂ O ₃ is 6% or more, it is possible to adjust to a thermal expansion coefficient suitable for molybdenum, kovar or tungsten used as an electrode, and processing in industrial production becomes easy. If it is more than%, the viscosity becomes sufficiently low, and it becomes easy to obtain a tube glass with good dimensional accuracy.

Al ₂ O ₃ is a component that remarkably improves the devitrification of glass, and its content is 0 to 10%, preferably 1 to 5%. If Al ₂ O ₃ is 10% or less, melting and processing in industrial production are facilitated, and if it is 6% or less, the viscosity is sufficiently low and tube glass with good dimensional accuracy is easily obtained. In order to produce homogeneous glass and perform stable molding, it is preferable to contain 1% or more.

Li 2 _O is an alkali metal _oxide, Na 2 _O, and K _{2 O} facilitates melting of the glass, as well as adjust the thermal expansion coefficient and viscosity, to reveal stably sulfide colloid borosilicate glass components It is. It also has the effect of reducing bubbles in the glass. The total content of alkali metal oxides is 3 to 20%, preferably 4 to 16%. If the total amount of these components is 20% or less, the coefficient of thermal expansion will not be too high, and it will be easy to match with that of the sealing electrode. If it is less than 16%, the occurrence of burns and the like due to a decrease in chemical durability is difficult to occur. On the other hand, if it is 3% or more, vitrification becomes possible. In addition, the coefficient of thermal expansion does not become too small, and it is easy to match with that of tungsten. If it is 4% or more, vitrification becomes easier, and a homogeneous glass free from bubbles and crystals is easily obtained. In order to increase the electrical resistance, it is desirable to use two or more alkali metal oxides, preferably three.

Li ₂ O, _Na 2 O, and the content of each of _{K 2} O is, each _Li 2 O _0~10% (particularly 0-4%, more _0.01~2%), Na 2 O _0~10 % (Especially 0 to 4%, more preferably 0.01 to ₂ %) and K2O 0 to 15% (especially 3 to 13%, more preferably 3 to 9%).

If the content of Li ₂ O is 10% or less, molding is possible in industrial production, and if it is within 4%, phase separation is difficult to occur. When the content is 0.01% or more, the effect of stabilizing the colloid can be obtained.

If Na ₂ O is 10% or less, the weather resistance does not deteriorate, and tube drawing is possible. If it is 4% or less, the thermal expansion coefficient is easily adapted to an electrode material such as tungsten. Considering the reaction with Hg in the fluorescent lamp, 2% or less is desired. When the content is 0.01% or more, the effect of stabilizing the colloid can be obtained.

If K ₂ O is 15% or less, the thermal expansion coefficient is easily adapted to an electrode material such as tungsten, and if it is 13% or less, the electrical resistance of the glass is not lowered, and if it is 9% or less, sufficient weather resistance is achieved. It is preferable because it can secure the property. In order to stabilize the colloid, it is preferable to contain the largest amount of K ₂ O among the alkali metal oxides. For these reasons, it is desirable to contain 3% or more.

  MgO and CaO have the effect of increasing the weather resistance, and their contents are each 0-8%, preferably 0-5%. If it is 8% or less, crystals do not precipitate in the glass, and if it is 5% or less, the stability of the glass is increased, which is preferable.

  SrO is a component introduced for the purpose of adjusting the viscosity of the glass and suppressing the crystal, and its content is 0 to 15%, preferably 0 to 5%. If it is 15% or less, crystals due to Sr itself do not precipitate in the glass, and if it is 5% or less, the stability of the glass is increased, which is preferable.

  BaO is a component introduced for the purpose of adjusting the viscosity of the glass and suppressing crystallization, and its content is 0 to 15%, preferably 1 to 8%. If it is 15% or less, crystals due to Ba itself do not precipitate in the glass, and if it is 8% or less, the stability of the glass is enhanced, and crystals are not precipitated without selecting production equipment. In addition, in order to acquire the above-mentioned effect, it is preferable to contain 1% or more in this invention.

  ZnO is a component introduced for the purpose of adjusting the viscosity of the glass and suppressing crystals, and its content is 0 to 15%, preferably 0 to 5%. If it is 15% or less, crystals due to Zn itself do not precipitate in the glass, and if it is 5% or less, the stability of the glass is increased, which is preferable.

ZrO ₂ is a component introduced for the purpose of improving the weather resistance of the glass, and its content is 0 to 9%, preferably 0 to 3%. If it is 9% or less, crystals due to Zr do not precipitate in the glass, and if it is 3% or less, the stability of the glass is increased, which is preferable. In addition, in order to acquire the above-mentioned effect, it is preferable to contain 0.001% or more in this invention.

Fe is an unavoidable component mixed from the glass raw material, but has an effect of preventing solarization by shielding ultraviolet rays. On the other hand, it is a coloring component itself and causes solarization by ultraviolet rays. Therefore, a suitable range exists and its content is from 0.003 to 0.05% represents the total Fe in _Fe 2 _{O 3,} it is particularly preferably from 0.005 to 0.02 percent. If Fe ₂ O ₃ is 0.003% or more, the effect of preventing solarization due to the ultraviolet shielding effect appears, and if it is 0.05% or less, there is no possibility of coloring the glass or causing solarization. Moreover, there is no possibility that the FeS colloid which causes coloring will be precipitated.

Fe is present in the glass in the state of Fe ²⁺ and Fe ³⁺ , and the abundance ratio reflects the redox of the glass. The lower the redox of the glass, the smaller the proportion of Fe ³⁺ . In the present invention, the value of Fe ³⁺ / total Fe amount representing the redox of the glass is preferably 0.4 or less, particularly preferably 0.2 or less. If it is 0.4 or less, colloidal particles are easily deposited, and ultraviolet rays of 313 nm or less can be effectively shielded. In addition, the solubility of SO _{3 in} the glass increases and reboiling bubbles are less likely to occur.

TiO ₂ is a component effective for preventing solarization, and its content is 0 to 10%, preferably 0.001 to 0.6%. More preferably, it is 0.01 to 0.6%. If it is 10% or less, no crystal is produced, and if it is 0.6% or less, coloring caused by Fe can be reduced. Moreover, although the said effect will appear if it contains 0.001% or more, in order to acquire sufficient effect, it is better to contain 0.01% or more.

Cl ₂ is effective as a fining agent, and the amount thereof is 0 to 0.5%, preferably 0.001 to 0.5%, more preferably 0.01 to 0, expressed as Cl ₂ in the residual amount in the glass. .5%. In order to obtain a sufficient effect as a fining agent, the residual amount needs to be 0.001% or more, preferably 0.01% or more. However, from the viewpoint of maintaining the working environment, it is better that the amount used is as small as possible, and it is necessary that the amount used is 0.5% or less.

The sulfur component is a component that forms a colloid and also has a function of causing the colloid in the glass to exist stably. Further, it is an effective component for improving the initial melting property of the glass raw material and finally reducing bubbles in the glass. On the other hand, it tends to cause bubble defects (residual bubbles and reboil bubbles) in glass products. The sulfur component is 0.005 to 1%, preferably 0.01 to 0.6%, more preferably 0.02 to 0.4% in terms of SO ₃ . If SO ₃ is 0.005% or more, the above-described effects can be obtained. Further, when S is contained in an amount more than the necessary amount for colloidal precipitation, the colloidal particles are stabilized. Therefore, it is preferably contained in an amount of 10% or more, more preferably 0.01% or more. By the way, the dissolved amount of SO _{3 in} the glass changes depending on the redox of the glass, and the dissolved amount increases as the glass is on the reduction side. The redox of the glass when a percentage of ^{Fe 3+, Fe 3+} / whole Fe amount is up to 1% as long as 0.2 or less, ^{Fe 3+} / whole Fe amount is 0.6% if not more than 0.4 Even if each of them contains SO ₃ , reboil bubbles are less likely to be generated by reheating. In addition, when the glass is molded into a thin tube and used, extremely high bubble quality is required. Therefore, even if the redox of the glass is on the reduction side, the content of SO ₃ should be 0.4% or less. .

  In addition to the above, various components can be added.

For example _Nb 2 O ₅ and _Ta 2 O ₅ is effective in terms of preventing solarization, it may be used in combination in place of TiO _2, or a TiO _2. Each of these contents is 0 to 10%, preferably 0 to 6%. If it is 10% or less, no crystal is produced in the glass, and if it is 6% or less, it is more preferable.

F and Br are effective as a clarifying agent like Cl ₂ , but the amount used is preferably as small as possible from the viewpoint of maintaining the working environment, and is preferably 0.5% or less in terms of residual amount.

Cr ₂ O ₃ is an effective component when correcting the coloring of Fe ions. The above effect can be expected if Cr ₂ O ₃ is contained in an amount of 0.00004% or more, particularly 0.0001% or more. On the other hand, since Cr ₂ O ₃ itself also colors the glass, a large amount of addition lowers the brightness of the glass, but if it is 0.1% or less, there is no effect in normal use and the use is severe in brightness. For this purpose, it may be 0.001% or less.

Sb ₂ O ₃ can be added up to 1.9% as a fining agent.

  Water in the glass is a factor that affects the viscosity of the glass and the formation of an oxide film of the electrode material. The content is represented by an infrared transmittance coefficient (X) represented by the following formula.

X = (log (a / b)) / t t = 1 mm
a: Transmittance (%) of a minimum point near 3840 cm ⁻¹
b: Transmittance (%) of the minimum point near 3560 cm ⁻¹

  In the case where the sealing beads are made of mantle tube glass, if the water content of the glass is large, the generation of an oxide film when sealing the electrode material becomes remarkable. The generation of the oxide film is necessary for improving the compatibility with the glass and performing the strong sealing. However, if the oxide film becomes too thick, there is a possibility that peeling occurs between the oxide film and the electrode metal. However, if the coefficient X representing the moisture content of the glass is 1.2 or less, the oxide film does not become too thick, and peeling between the oxide film and the electrode metal hardly occurs. When the coefficient X is 0.8 or less, particularly 0.6 or less, reliable sealing can be performed. On the other hand, the moisture in the glass has an effect of moderating the viscosity change in the low temperature range of the glass. In the case of a thin glass jacket tube used for a fluorescent lamp for an illuminating device of a liquid crystal display element, The larger the amount, the more advantageous from the processing surface. That is, in the tube glass having a small tube thickness and a small heat capacity, the glass is rapidly softened by heating, so that the smaller the viscosity change in the low temperature region, the easier it is to process. For this reason, the coefficient X is desired to be 0.2 or more, particularly 0.3 or more. When the electrode material is sealed in a neutral atmosphere, it is recommended that the coefficient X be 0.3 or more in order to sufficiently form an oxide film on the electrode surface.

  The amount of moisture in the glass is adjusted by the moisture in the combustion gas and the glass raw material (particularly, the mixing ratio of boric acid and boric anhydride). In addition, when these cannot be adjusted, they can be adjusted by bubbling with dry air or water vapor.

The thermal expansion coefficient of the glass can be appropriately adjusted according to the electrode material used. However, the glass used in the present invention is more reducible than conventional glass because of the precipitation of colloidal particles. According to the knowledge of the present inventors, when producing sealing beads with such an envelope glass material, there is a tendency that a metal oxide film is not easily formed on the electrode material at the time of electrode sealing, and reliable sealing. In order to carry out the process, it has been found desirable to determine the coefficient of thermal expansion of the glass so that it can be compression sealed in the radial direction with respect to the electrode at 5-100 kgf / cm ² , preferably 10-60 kgf / cm ² . . The suitable thermal expansion coefficient of the glass with respect to each electrode material is shown below.

When the electrode material is Kovar, since there is a Curie point, a suitable thermal expansion coefficient changes corresponding to the strain point Ps of glass (temperature corresponding to a viscosity of 10 ^14.5 d · Pa / s). The optimal thermal expansion coefficient αp (× 10 ⁻⁷ / ° C.) of the glass at 30 to 380 ° C. is obtained by the following formula.

        αp = (Ps−450) / 5 + 50

The allowable range of the difference between the optimum thermal expansion coefficient αp determined by the above formula and the actual expansion coefficient is ± 5 × 10 ⁻⁷ / ° C. If the thermal expansion coefficient of the glass is αp ± 5 × 10 ⁻⁷ / ° C., compression sealing can be performed stably. In order to obtain more accurate compression sealing, αp ± 2.5 × 10 ⁻⁷ / ° C. is sufficient.

When the electrode material is molybdenum, a suitable glass has a thermal expansion coefficient of 46 to 59 × 10 ⁻⁷ / ° C., particularly 50 to 55 × 10 ⁻⁷ / ° C. (30 to 380 ° C.).

When the electrode material is tungsten, a suitable glass has a thermal expansion coefficient of 37 to 45 × 10 ⁻⁷ / ° C., particularly 39 to 42 × 10 ⁻⁷ / ° C. (30 to 380 ° C.).

  Next, a method for manufacturing the outer tube for the fluorescent lamp of the present invention made of the above glass will be described.

  First, glass raw materials are prepared so as to have a desired composition, and after melting at 1550 to 1600 ° C., the melt is formed into a tubular shape. As a forming method, a pipe drawing method such as a down draw method, a dunner method, or an up draw method may be employed. When used as a fluorescent lamp for an illuminating device of a liquid crystal display element, it is preferably formed into a thin tube having a diameter of 8 mm or less and a wall thickness of 0.6 mm or less. Subsequently, the tubular glass is cut into a predetermined size and post-processed as necessary. In actual production, facilities are usually designed so that the glass is rapidly cooled in the tube glass manufacturing process, and it is difficult to produce colloidal particles in the glass. In such a case, the produced tube glass may be further heat-treated at a temperature of 450 ° C. or higher to precipitate colloidal particles. If there is no restriction on equipment, heat treatment for colloid generation may be incorporated in a series of molding steps. In this way, a fluorescent lamp envelope can be obtained in which colloidal particles are deposited in glass.

  The obtained outer tube is used for production of a fluorescent lamp according to a conventional method. As the electrode material, Kovar, molybdenum, tungsten or the like is appropriately selected in accordance with the expansion and viscosity characteristics of the glass. If the sealing beads for sealing the electrodes are made of the same material as the outer tube glass, it is preferable in terms of efficiency in the lamp manufacturing process. However, it goes without saying that sealing beads may be made of other materials.

  Hereinafter, the present invention will be described based on examples.

  Table 1 shows examples (samples No. 1 to 6) and comparative examples (No. 7) of the outer tube of the present invention.

  Each sample was prepared as follows. First, as glass raw materials, stone powder, boric acid, alumina, lithium carbonate, sodium carbonate, potassium carbonate, potassium nitrate, salt, magnesium carbonate, calcium carbonate, strontium carbonate, barium carbonate, zinc oxide, zinc sulfide, zircon, titanium oxide, sulfur, Niobium pentoxide, chromium oxide, etc. were prepared. In addition, the kind of raw material is not limited to this, What is necessary is just to select suitably considering the oxidation reduction state of glass, moisture content, etc. The composition shown in the table is a converted value and is not limited to the indicated oxide valence.

  Next, a predetermined amount of each glass raw material was prepared and melted at 1550 ° C. in a refractory furnace, and then the melt was supplied to a dunner apparatus to be formed into a tubular shape and processed. Further, in order to generate a colloid in the glass, a sample was obtained by heat treatment at 580 ° C. for 3 minutes. The heat treatment was performed while applying rotation on two adjacent precision-formed rotating rollers so that the pipe was not warped, bent, stretched or deformed. The method of heating while preventing deformation of the tube is not limited to the above. For example, a method of inserting a tube glass into a cylindrical roller and performing a heat treatment while applying rotation can be employed.

  Various evaluations were performed on the samples thus prepared. In evaluating various properties, an evaluation sample that was molded into a predetermined shape and then heat-treated under the same colloid deposition conditions was used. The results are shown in Table 1.

  From Table 1, sample No. which is an example of the present invention is shown. In Nos. 1 to 6, ZnS colloidal particles were deposited, and it was confirmed that ultraviolet rays of 313 nm or less can be shielded. Further, from the values of thermal expansion coefficient and strain point, the sample No. Nos. 1 to 5 are suitable for Kovar sealing. 6 was found to be suitable for tungsten sealing.

  In addition, in order to confirm whether or not the outer tube of the present invention can be used as a sealing bead, no. When the sealing test (evaluation of sealing stress and interfacial foam at the time of sealing) was performed using the samples 2, 5, and 6, good results were obtained in all cases.

In addition, the content of Fe ₂ O ₃ and Cl _{2 in} the table is the value confirmed by ICP-MS after treating the glass with acid after the content of SO ₃ and Cr ₂ O ₃ by fluorescent X-ray analysis. is there. Presence or absence of colloidal particles was confirmed with a transmission electron microscope. The type of colloid was estimated from the glass composition. The value of Fe ³⁺ / total Fe amount was determined according to ASTM C 169-92. The infrared transmittance coefficient (X) is obtained by substituting the transmittance a at the minimum point near 3840 cm ⁻¹ and the transmittance b at the minimum point near 3560 cm ⁻¹ measured with an infrared spectrophotometer into the following equation. It was. Note that t is the sample thickness (1 mm).

      X = (log (a / b)) / t

  The linear thermal expansion coefficient is a value obtained by measuring an average linear expansion coefficient in a temperature range of 30 to 380 ° C. with a self-recording differential thermal dilatometer using an evaluation sample processed into a cylinder having a diameter of about 3 mm and a length of about 50 mm. .

  Coloring was determined as follows. First, a plate-like sample for evaluation having a thickness of 10 mm with both surfaces mirror-polished is prepared, the brightness Y value is 90% or more, and the chromaticity coordinates x = 0.3190, y = 0.3278 (according to JIS Z 8701) The limit sample, which was measured using a transmittance measuring device under the condition of a C light source with a field of view of 2 °, was compared with the coloring, and the case where the color was whiter than the sample was marked with “◯”.

  The ultraviolet solarization resistance was evaluated by the difference in transmittance in the visible region before and after the ultraviolet irradiation. First, both sides were mirror-polished to prepare a plate-like sample for evaluation having a thickness of 1 mm. Next, the wavelength of light at which the transmittance of the sample before ultraviolet irradiation showed 80% was measured. Furthermore, after irradiating the sample with ultraviolet light having a main wavelength of 185 nm and 254 nm for 60 minutes with a 40 W low-pressure mercury lamp (irradiation distance: 24 mm), the transmittance at a wavelength showing a transmittance of 80% was measured again before irradiation, The decrease in transmittance due to ultraviolet irradiation was determined. At this time, the lower the transmittance of the glass is, the more the glass is inferior in ultraviolet solarization resistance. However, it is important that the outer glass of the fluorescent lamp used in the illuminating device of the liquid crystal display element has almost no decrease in the transmittance. In consideration of errors, the drop in this case was 0.2% or less, and “◯” was over 0.2% and 0.5% or less.

  The spectral transmittance of 313 nm was prepared by preparing a plate sample for evaluation having a thickness of 0.2 mm with both surfaces mirror-polished and measuring the spectral transmittance of a wavelength of 313 nm. The excess was taken as “x”.

  For the number of bubbles, observe a 10 g block-shaped measurement sample, count the number of bubbles (bubbles with a diameter of about 50 μm or more) that can be seen with a 40-fold microscope. It was. Two to five pieces were set as “Δ”.

  For reboiling, a sample for evaluation of about 1 cm square was heated and welded to the tip of a glass rod, ignited with a burner, and then observed for the occurrence of bubbles. did.

  The liquid phase viscosity was determined as follows. First, glass crushed to a particle size of about 0.1 mm was placed in a boat-shaped platinum container, held in a temperature gradient furnace for 24 hours, and then taken out. The sample was observed with a microscope to measure the temperature at which the initial phase of the crystal emerges (liquid phase temperature), and then the viscosity corresponding to the temperature of the initial phase (from the relationship between the glass temperature and viscosity measured in advance) (Liquid phase viscosity) was determined. A liquid phase viscosity logarithm display (log ρ dPa · S) of 5 or more was designated as “◯”. The temperature corresponding to each viscosity was determined by ASTM C336, ASTM C338 and the ball pulling method. If the logarithmic value of the liquid phase viscosity is 5 or more, it is advantageous for mass production of thin tubes.

  The sealing stress was measured by inserting an electrode material having a diameter of 0.5 mm into a tubular evaluation sample having an inner diameter of 0.7 mm, an outer diameter of 2.2 mm, and a length of 2 mm, and heating it into a bead shape in a nitrogen atmosphere. The sample compressed and sealed in the radial direction was expressed as “compressed”. Usually, the observation in the axial direction is easy, and it can be considered that the one where tensile stress is generated in the axial direction is compressed in the radial direction.

  The sealing foam was observed as “O” when the surface of the electrode in the bead was observed with a 10 × microscope and there was no continuous foam.

  Next, regarding the sealing properties of the mantle tube and sealing beads of the present invention, Sample No. Evaluation was performed using 2, 5, and 6. Table 2 shows examples (samples a to d) of the present invention.

  From Table 2, it was confirmed that the outer tube for a fluorescent lamp of the present invention has good sealing properties with sealing beads.

  The interface foam was heated by inserting a bead into an outer tube having an inner diameter of 2.4 mm, and the adhesion interface between the outer tube and the bead was observed with a 10 × microscope. .

  The He leak test was detected by sealing one end of the outer tube with beads, connecting the other end to a He leak detector, which is a type of mass analyzer, and spraying helium gas on the sealed portion. The case where the measured value did not change when helium gas was blown was marked as “◯”.

  The outer tube for a fluorescent lamp of the present invention can also be used as a sealing bead material. Further, it can be used as a fluorescent lamp other than a cold cathode lamp outer tube, for example, an outer electrode fluorescent lamp (EEFL) outer tube.

Claims (8)

In mass percentage,
SiO ₂ 55~76%,
B ₂ O ₃ 6-25%,
Al ₂ O ₃ 0-10%,
Li ₂ O 0-10%,
Na ₂ O 0-10%,
K ₂ O 0-15%,
Li ₂ O + Na ₂ O + K ₂ O 3-20%,
MgO 0-8%,
CaO 0-8%,
SrO 0-15%,
BaO 0-15%,
ZnO 0-15%,
ZrO ₂ 0-9%,
Fe ₂ O ₃ 0.003~0.05%,
TiO ₂ 0-10%,
Cl ₂ 0-0.5%,
SO ₃ 0.005~1%
An outer tube for a fluorescent lamp comprising a borosilicate glass containing colloidal particles.   The outer tube for a fluorescent lamp according to claim 1, wherein the colloidal particles are ZnS colloids. The outer tube for a fluorescent lamp according to claim 1 or 2 , wherein the amount of Fe ³⁺ / total Fe is 0.4 or less. The outer tube for a fluorescent lamp according to any one of claims 1 to 3 , wherein the outer tube is a thin tube having a diameter of 8 mm or less and a wall thickness of 0.6 mm or less. A fluorescent lamp manufactured using the outer tube of any one of claims 1 to 4 . 6. The fluorescent lamp according to claim 5 , wherein the electrode is sealed with sealing beads made of the same material as the outer tube. The fluorescent lamp according to claim 6 , wherein the electrode is made of Kovar, molybdenum or tungsten. The fluorescent lamp according to claim 5 , wherein the fluorescent lamp is used as a light source of an illumination device for a liquid crystal display element.