JPWO2007086441A1 - Method for producing glass composition for lamp, glass composition for lamp and lamp - Google Patents

Abstract

In a method for manufacturing a glass composition for a lamp, a raw material mixture in which an oxide of a predetermined element and a hydroxide of the predetermined element are added in a molar ratio of oxide / hydroxide = 1/3 to 1, a glass state The raw material mixture is heated so that a gas composed of at least one of H2O and H2 is generated from the hydroxide by a decomposition reaction of the hydroxide. This makes it possible to produce a glass with few bubbles without generating harmful gases.

Description

  The present invention relates to a method for producing a glass composition for a lamp, a glass composition for a lamp produced using the method, and a lamp produced using the glass composition for a lamp.

  In general, a fluorescent lamp is used as a light source in a backlight of a transmissive liquid crystal display element such as a liquid crystal TV or a personal computer display. The fluorescent lamp for backlight has basically the same configuration as the fluorescent lamp for general illumination, but the tube diameter of the glass bulb is smaller and the wall thickness is thinner. Therefore, a borosilicate hard glass (hereinafter simply referred to as “borosilicate glass”) having high mechanical strength and excellent electrical insulation is used for such a fluorescent lamp for backlight.

  By the way, when air bubbles are present in the glass of the glass bulb, the mechanical strength of the glass bulb is reduced and breakage is likely to occur. Such a decrease in strength becomes a serious problem particularly in a glass bulb having a small tube diameter and a small thickness. Therefore, conventionally, arsenic or antimony is added to glass as a fining agent, and bubbles are removed from the glass (glass is clarified).

However, arsenic and antimony are environmentally hazardous substances that adversely affect the environment. Therefore, glass added with arsenic or antimony is not suitable for recycling. In addition, arsenic and antimony-added glass require careful handling in manufacturing factories and waste disposal factories, and require a large amount of equipment for detoxifying the etching waste liquid.
In order to cope with this type of problem, Patent Document 1 discloses a method for producing glass in which an effective amount of a salt containing SO ₃ , Cl 2 and F as a fining agent is added. With this method, it is possible to obtain a glass with less bubbles without adding an environmental load substance. It is also known that a clarification effect can be obtained by adding nitrates such as NaNO ₃ and KNO ₃ to glass.
JP 2004-284949 A

However, in the manufacturing method of Patent Document 1, gas harmful to the human body such as sulfide gas and halogen gas is generated in the glass melting step. Generation | occurrence | production of such noxious gas is unpreferable in order to deteriorate the working environment of glass manufacture.
Also, the addition of nitrate is not preferable because nitric acid gas (NOx) harmful to the human body is generated and the working environment of glass production is deteriorated.

  The objective of this invention is providing the manufacturing method of the glass composition for lamps which can manufacture glass with few remaining bubbles, without producing | generating harmful gas. Another object of the present invention is to provide a lamp glass composition with few bubbles that can be produced without generating harmful gases, and a lamp that is made of the glass composition for lamps and is less likely to break. There is.

In order to achieve the above object, a method for producing a glass composition for a lamp according to an embodiment of the present invention is characterized in that an oxide of a predetermined element and a hydroxide of the predetermined element are oxide / hydroxide = 1 / Including a melting step of melting a raw material mixture added at a molar ratio of 3 to 1 into a glass state, and in the melting step, H ₂ O or H ₂ is converted from the hydroxide by a decomposition reaction of the hydroxide. The raw material mixture is heated so that at least one gas is generated.

A glass composition for a lamp according to an embodiment of the present invention is a glass composition for a lamp produced by the above method for producing a glass composition for a lamp, and has a minimum value of infrared transmittance in the vicinity of a wavelength region of 3620 cm ^−1. Is 3.0 to 4.5% at a sample thickness of 2 mm.
The lamp | ramp which concerns on one Embodiment of this invention is equipped with the glass bulb | ball formed with the said glass composition for lamps, It is characterized by the above-mentioned.

In the method for producing a glass composition for a lamp according to the present invention, a gas composed of at least one of H ₂ O and H ₂ is generated from a hydroxide of a predetermined element in the melting step, so that bubbles are generated without generating harmful gas. It has the effect that a glass with a small amount can be produced. The effect will be described in detail below.
As a result of various studies, the inventors have replaced the oxide of the predetermined element added to the raw material mixture with the hydroxide of the predetermined element, thereby melting the raw material mixture into a glass state. In the process, it was found that gas was generated from the hydroxide, and bubbles in the glass melt were removed by the gas, and a clarification effect was obtained. Gas generated from the hydroxide is for generating the decomposition reaction of the hydroxide, of at least one of H ₂ O or H _2. A clarification effect is obtained by the decomposition reaction of the hydroxide occurring in a temperature range of 500 to 1000 ° C. at which the vitrification reaction is started.

In the first place, the bubbles present in the glass are those in which a gas such as CO ₂ generated when the raw material mixture is melted into the glass state remains without being completely removed from the glass melt. In particular, the bubbles of CO ₂ have a small diameter, have a low buoyancy, and are difficult to float from the glass melt, and therefore cannot easily escape from the glass melt and remain in the glass.
In order to remove such small-diameter bubbles, in the method for manufacturing a glass for a lamp according to the present invention, a gas composed of H ₂ O or H ₂ is generated from a hydroxide of a predetermined element. Since the gas bubbles made of H ₂ O and H ₂ have a larger diameter than bubbles such as CO ₂ , the buoyancy is larger, and the bubbles easily escape from the glass melt and hardly remain in the glass. The gas bubbles composed of H ₂ O and H ₂ take in bubbles such as CO ₂ when they rise from the glass melt, so that small-sized bubbles composed of CO _{2 and the} like are also removed from the glass.

However, when a gas composed of H ₂ O or H ₂ is generated in the glass melt, there is a problem that moisture tends to remain in the glass. If the amount of water remaining in the glass is large, the water vaporizes when heated, and refoaming (reboiling) is likely to occur. When a lamp is manufactured from such glass, it is reheated to a part that has been overheated by a burner or the like during heat processing. Foaming can cause slow leaks and cracks.

In response to this problem, the present inventors may make refoaming difficult to occur while sufficiently obtaining a clarification effect by defining the mixing ratio of oxide and hydroxide in the range of 1/3 to 1. I found it possible.
When the mixing ratio is greater than 1, the clarification effect is insufficient because the amount of gas composed of H ₂ O and H ₂ is small. On the other hand, when the mixing ratio is less than 1/3, re-foaming is likely to occur during heat processing, which is not suitable for a lamp.

As the predetermined element, boron (B), aluminum (Al), calcium (Ca) and the like can be considered, and in this case, the hydroxide of the predetermined element is H ₃ BO ₃ , Al (OH) ₃ and Means Ca (OH) ₂
The hydroxide according to the present invention includes not only a narrowly defined hydroxide, that is, a compound having a hydroxyl group, but also a broadly defined hydroxide, that is, a compound having a hydrogen element and an oxygen element. For example, not only narrow hydroxides such as Al (OH) ₃ and Ca (OH) ₂ , but also broad hydroxides such as H ₃ BO ₃ (which can be expressed as B (OH) ₃ ) Including.

The method for producing a glass composition for a lamp according to the present invention is such that the oxide and hydroxide are such that the content of the predetermined element in the glass composition for a lamp is 8 to 17 mol% in terms of oxide. When added to the mixture, it is possible to obtain a glass composition for a lamp which has good meltability and sealing property of the lead-in wire and hardly causes phase separation.
The method for producing a glass composition for a lamp according to the present invention is such that the hydroxide is such that the content of the predetermined element in the glass composition for a lamp is 5 to 10.5 mol% in terms of oxide. When added to the lamp, it is possible to obtain a glass composition for a lamp in which there are few bubbles and re-foaming hardly occurs during heat processing.

In the method for producing a glass composition for a lamp according to the present invention, the clarification effect is particularly remarkable when the glass composition for a lamp is borosilicate glass and the predetermined element is boron. For example, H ₃ BO ₃ which is a hydroxide of boron generates a gas composed of at least one of H ₂ O or H ₂ by a decomposition reaction in a wide temperature range of 300 to 800 ° C., so that temperature control is performed in the melting process. Is easy. The decomposition reaction of H ₃ BO ₃ is represented by the following (formula 1) and (formula 2).

2H ₃ BO ₃ → 3H ₂ O + B ₂ O ₃ (Formula 1)
2H ₃ BO ₃ → 3 / 2O ₂ + 3H ₂ + B ₂ O ₃ (Formula 2)
Furthermore, there is an effect that glass can be manufactured at low cost by using inexpensive H ₃ BO ₃ , and an effect that glass is not colored even if H ₃ BO ₃ is added in a large amount.
In the present invention, the borosilicate glass is a glass having a high Young's modulus and Vickers hardness and excellent mechanical strength, and specifically contains ₆ to 20 mol% of B ₂ O _{3 in} terms of oxide. Means glass.

Lamp glass composition according to the present invention, when the thermal expansion coefficient (α _30/380) of ^{34 × 10 -7 / K~43 × 10} -7 / K, or, 43 × 10 ^-7 / K~55 The following effects are obtained when × 10 ^-7 / K.
Generally, a lead lamp made of tungsten or Kovar alloy that can withstand high temperatures caused by discharge is used for a backlight lamp. Therefore, in order to increase the reliability of the hermetic seal of the lead-in wire, it is preferable to make the thermal expansion coefficient of the glass composition for lamps close to the thermal expansion coefficient of tungsten or Kovar alloy.

When the thermal expansion coefficient (α _30/380 ) is 34 × 10 ⁻⁷ / K to 43 × 10 ⁻⁷ / K, it is similar to the thermal expansion coefficient of the tungsten lead wire and has high chemical durability. The reliability of the airtight seal of the lead-in line is high.
When the coefficient of thermal expansion (α _30/380 ) is 43 × 10 ⁻⁷ / K to 55 × 10 ⁻⁷ / K, it is the same as the coefficient of thermal expansion of the Kovar alloy lead wire and has high chemical durability. The reliability of the airtight seal of the lead-in line is high.
The lamp | ramp which concerns on this invention is equipped with the glass bulb | ball formed with the said glass composition for lamps. Therefore, there are few bubbles in the glass of the glass bulb, and the lamp is not easily damaged.

The composition and characteristic of the glass composition concerning one embodiment of the present invention are shown. It is the schematic which shows the principal part structure of the cold cathode fluorescent lamp which concerns on one Embodiment of this invention. The composition and characteristic of the glass composition which concerns on a comparative example are shown. It shows the infrared transmittance at a range of 2800cm ^-1 ~3800cm ^-1 glass composition according to one embodiment of the present invention. It shows the infrared transmittance at a range of 3600cm ^-1 ~3800cm ^-1 glass composition according to one embodiment of the present invention.

Explanation of symbols

  1 lamp

A glass composition for a lamp, a method for producing a glass composition for a lamp, and a lamp according to an embodiment of the present invention will be described with reference to the drawings.
(Description of glass composition for lamp)
The composition of the glass composition according to the present embodiment is as shown in Examples 1 to 5 in FIG. Note that “%” in FIG. 1 means “mol%”.

The composition of the glass composition according to the present invention is not limited to the compositions shown in Examples 1 to 5, but in order to maintain the characteristics as a glass composition for a lamp, it is substantially SiO _{2 in} terms of oxide. _{: 55~75mol%, Al 2 O 3} : 1~10mol%, B 2 O 3 + H 3 BO 3: 8~17mol%, Li 2 O + Na 2 O + K 2 O: 0~12mol%, Li 2 _{O: 0~5mol%, Na 2 O} : 0~8mol%, K 2 O: 0~12mol%, MgO: 0.5~5mol%, CaO: 0.5~10mol%, SrO: 0~8mol%, BaO: 0~ _{10mol%, CeO 2: 0.01~2mol%} , Fe 2 O 3: 0~0.2mol%, SnO: is preferably 0.01 to 5 mol%.

In the present embodiment, the boron (B) contained in the glass composition includes those added to the raw material mixture as boron oxide and those added to the raw material mixture as boron hydroxide. However, in order to distinguish between them, “B ₂ O ₃ ” is used for those added as oxides, and “H ₃ BO ₃ ” is used for those added as hydroxides. These are the same in FIG. 1 and FIG. 3 described later.

Therefore, in the above, the meaning described as B ₂ O ₃ + H ₃ BO ₃ : 8 to 17 mol% means the total amount of boron added as an oxide and boron added as a hydroxide in the glass composition. The value in terms of oxide is 8 to 17 mol%.
The reason for determining the glass composition for a lamp of the present invention as described above is as follows.
SiO ₂ is a component that forms a glass skeleton, and its content is preferably in the range of 55 to 75 mol%. If it is less than 55 mol%, the coefficient of thermal expansion becomes too high and the chemical durability deteriorates. On the other hand, if it exceeds 75 mol%, the coefficient of thermal expansion becomes too low and it becomes difficult to process and mold.

Al ₂ O ₃ is a component added for the purpose of improving the weather resistance and devitrification of glass, and its content is preferably in the range of 1 to 10 mol%. When the amount is less than 1 mol%, it is difficult to obtain the above action. On the other hand, if it exceeds 10 mol%, the meltability of the glass deteriorates. The content is particularly preferably 2 to 7 mol%.
B ₂ O ₃ is an essential component of this example that is added for the purpose of improving the meltability of glass, adjusting the expansion coefficient, and adjusting the viscosity.

H ₃ BO ₃ is an essential component of this example that is added for the purpose of improving the meltability of the glass, adjusting the expansion coefficient, adjusting the viscosity, and promoting the clarification effect.
B ₂ O ₃ + H ₃ BO ₃ is preferably in the range of 8 to 17 mol%. When B ₂ O ₃ + H ₃ BO ₃ is less than 8 mol%, the meltability of the glass deteriorates, and the viscosity and the expansion coefficient increase to make it difficult to seal the lead-in wire. On the other hand, if it exceeds 17 mol%, the glass undergoes phase separation, making it difficult to produce the glass. The total content is particularly preferably 10 to 16 mol%.

B ₂ O ₃ and H ₃ BO ₃ are added so as to have a molar ratio of B ₂ O ₃ / H ₃ BO ₃ = 1 / 3-1. When the molar ratio is less than 1/3, re-foaming occurs in the overheated portion by the burner during thermal processing of the fluorescent lamp, which causes slow leaks and cracks. On the other hand, if the molar ratio is greater than 1, the glass refining effect is insufficient.
Alkali metal oxides of Li ₂ O, Na ₂ O and K ₂ O are added for the purpose of reducing the viscosity of the glass and improving the melt processability. The content is preferably in the range of 0 to 10 mol%. If it exceeds 10 mol%, the thermal expansion coefficient of the glass becomes too large. In addition, since alkali components are easily eluted from the glass, when a fluorescent lamp is manufactured using the glass, the glass reacts with the phosphor or mercury to reduce the luminous flux of the fluorescent lamp. The content of each component is preferably Li ₂ O: 0 to 5 mol%, Na ₂ O: 0 to 8 mol%, and K ₂ O: 0 to 12 mol%.

  MgO and CaO alkaline earth metal oxides are added for the purpose of improving electrical insulation and chemical durability. The content of MgO is preferably in the range of 0.5 to 5 mol%, and the content of CaO is preferably 0.5 to 10 mol%. If MgO is less than 0.5 mol% or CaO is less than 0.5 mol%, the above object may not be achieved. On the other hand, when MgO is more than 5 mol% or when CaO is more than 10 mol%, the glass tends to devitrify.

SrO and BaO are added for the purpose of improving the meltability of the glass and the bulb processability when manufacturing the fluorescent lamp. The SrO content is preferably 0 to 8 mol%, and the BaO content is preferably 0 to 10 mol%. When SrO is more than 8 mol% or BaO is more than 10 mol%, the glass tends to devitrify.
CeO ₂ is added for the purpose of effectively absorbing ultraviolet rays and suppressing solarization. The content is preferably in the range of 0.01 to 2 mol%. If the amount is less than 0.01 mol%, the object cannot be achieved. If the amount is more than 2 mol%, devitrification of the glass occurs, making it difficult to produce a fluorescent lamp having a desired lamp luminous flux. The content is particularly preferably in the range of 0.01 to 1 mol%.

Fe ₂ O ₃ is added for the purpose of obtaining an ultraviolet absorption effect. The content is preferably in the range of 0 to 0.2 mol%. If it exceeds 0.2 mol%, the transmittance in the visible region is lowered, and therefore the luminous flux of the fluorescent lamp is lowered, which is not preferable.
SnO is added for the purpose of promoting the valence change of Ce ions from 4+ to 3+. The content is preferably in the range of 0.01 to 5 mol%. If the amount is less than 0.01 mol%, the effect cannot be obtained. If the amount is more than 5 mol%, the mechanical strength of the glass is lowered and the yield is lowered in the glass tube drawing process. The range of 0.1 to 3 mol% is particularly preferable.

In addition, the glass which concerns on this invention should just contain the content rate of each component in said range substantially, and the other component may be contained in the limit which does not deviate from the range of the said composition. Examples of other components include ZrO ₂ , ZnO, P ₂ O ₅ , TiO ₂ , and WO ₃ .
Conventionally, CeO ₂ is known as one of the fining agents, but the fining effect cannot be obtained unless a large amount is added. However, if it is added in a large amount to obtain a clarification effect, a problem of coloring the glass occurs. Therefore, even when substantially only CeO ₂ is added as a clarifier, it is difficult to produce a glass that is colorless and has few remaining bubbles.

SnO _{2 is} also known as a fining agent, but as with CeO ₂ , a fining effect cannot be obtained unless a large amount is added. However, if a large amount is added to obtain a clarification effect, a problem that the glass devitrifies occurs. Therefore, even if only SnO ₂ is substantially added as a fining agent, it is difficult to produce a glass with no devitrification and few remaining bubbles.
(Description of manufacturing method of glass composition for lamp)
In the method for producing a lamp glass composition according to this embodiment, first, a plurality of types of glass raw materials are prepared within the range of the composition of the lamp glass composition according to the present invention to obtain a raw material mixture. Next, the raw material mixture is put into a glass melting furnace and melted at 1500-1600 ° C. for 5-8 hours in an air atmosphere to obtain a glass melt. At that time, treatments such as stirring and bubbling are not performed. Thereafter, the glass melt is formed into a tubular shape by a tube drawing method such as the Danner method, and cut into a predetermined size to obtain a glass tube for a lamp. Furthermore, the glass tube is heat-processed to produce a glass bulb, and various lamps are produced.

In addition, it is not limited to the procedure which mix | blends a glass raw material and makes it a raw material mixture, and throws into a glass melting kiln, A part of glass raw material is thrown into a glass melting kiln at a different timing from other glass raw materials, and glass melting It is also conceivable to prepare the raw material mixture in the kettle.
(Lamp description)
As an embodiment of the lamp according to the present invention, a straight tube type cold cathode fluorescent lamp will be described with reference to the drawings. FIG. 2 is a schematic view showing a main configuration of the cold cathode fluorescent lamp according to the present embodiment. The structure of the cold cathode fluorescent lamp 1 basically conforms to the structure of the cold cathode fluorescent lamp according to the prior art.

  The glass bulb 2 of the cold cathode fluorescent lamp 1 is formed by the lamp glass composition according to the present embodiment, and has an outer diameter of about 4.0 mm, an inner diameter of about 3.0 mm, and an overall length of about 730 mm. It is. The outer diameter, inner diameter, and overall length of the glass bulb 2 are not limited to the above. However, since the glass bulb 2 for the cold cathode fluorescent lamp 1 is desired to have a small tube diameter and a small thickness, the outer diameter is 1.8. The inner diameter is preferably 1.4 to 6.0 (inner diameter is 5.0) mm.

  Both ends of the glass bulb 2 are hermetically sealed with bead glass 3. Further, at both ends of the glass bulb 2, lead wires 4 made of tungsten metal or Kovar alloy having a diameter of about 0.8 mm are hermetically sealed so as to penetrate the bead glass 3. Then, a nickel or niobium cup-shaped electrode 5 whose surface is coated with an electron radioactive substance is attached to an end portion of each lead-in wire 4 on the inner side of the glass bulb 2.

On the inner surface of the glass bulb 2, a rare earth phosphor (Y ₂ O ₃ : Eu ³⁺ , LaPO ₄ : Ce ³⁺ , Tb ³⁺ , BaMg ₂ Al, which is a mixture of red, green and blue-green phosphors) _A phosphor layer 6 formed by coating ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ ) is formed. Further, 0.8 to 2.5 mg of mercury (not shown) and a rare gas such as xenon (not shown) are sealed inside the glass bulb 2.
As mentioned above, although the straight tube | pipe type cold cathode fluorescent lamp 1 which concerns on this invention has been concretely demonstrated based on embodiment, the content of this invention is not limited to said embodiment.

(Explanation of experiment)
A glass composition for a lamp according to the present embodiment shown in FIG. 1 and a glass composition for a lamp according to a comparative example shown in FIG. 3 were prepared, and their characteristics were evaluated and compared.
Each glass composition was prepared by weighing 17 g of the raw material mixture adjusted to the composition shown in the figure, putting it in a platinum crucible and heating and melting it at 1500 ° C. for 3 hours in an electric furnace, and then taking it out from the electric furnace, Was made by contacting with cold water and quenching, and peeling the interface between the glass and the crucible.

The coefficient of thermal expansion (α _30/380 ) and glass transition point were obtained by molding each glass composition into a cylindrical shape with a diameter of 5.0 mm and a length of 15 mm, and a thermomechanical analyzer (manufactured by Rigaku, model number: TAS300 TMA8140C) The average linear expansion coefficient in the temperature range of 30 to 380 ° C. was measured.
The number of bubbles was counted using image processing software for the number of bubbles confirmed in the central part of the cross section of the glass composition 120 mm ² and the plate thickness 3 mm. Only bubbles having a diameter of 30 μm or more were counted as bubbles.

The number of bubbles is cut to 120mm ² (10mm x 12mm) and 3mm in thickness at the center of the cross section of the glass composition, and then both sides of the glass are graded to # 400, # 800, # 1000, # 1500, # 2000 Was polished and finished to a mirror surface to make a glass sample. The number of bubbles confirmed in the glass sample was counted using image processing software. Only bubbles having a diameter of 30 μm or more were counted as bubbles.

In the remaining bubble determination, a case where the number of bubbles exceeded 350 was determined as “×”, and a case where the number of bubbles was 350 or less was determined as “◯”. This is because it has been confirmed that when a lamp is produced with a glass composition having more than 350 bubbles, a significant decrease in yield occurs.
Re-foaming at the time of heat processing, when the glass composition is heat-processed, if a bubble having a diameter of 30 μm or more occurs in the overheated portion, it is judged as “×” with re-foaming, and when re-foaming does not occur, "".

Infrared transmittance was measured in a wavelength range of 2800 to 3800 cm ⁻¹ for a glass composition having a sample thickness of 2 mm with both surfaces mirror-polished using FT-IR (FTIR-8200 manufactured by Shimadzu Corporation). When evaluating an actual bulb, a glass plate having a thickness of 2 mm was produced by treating the glass bulb with a softening point of + 20 ° C. for 3 hours to soften the bulb. Thereafter, the glass plate was cut into a square of 15 mm length × 15 mm width to obtain a sample for evaluation of 15 mm length × 15 mm width × 2 mm thickness. Both surfaces of the sample for evaluation were polished step by step up to # 400, # 800, # 1000, # 1500, and # 2000, and finished to mirror surfaces.

The measurement results are shown in FIG. The infrared transmittance was performed for the purpose of evaluating the amount of water remaining in the glass composition. The moisture remaining in the glass composition is generated by the decomposition reaction of H ₃ BO ₃ , and a part of the moisture is dissolved in the glass composition. If the amount of water dissolved in the glass composition is large, the water dissolved when the glass composition is heat-processed is gasified and re-foaming occurs.
The amount of water in the glass composition can be confirmed by the minimum value of infrared transmittance in the vicinity of 3620 cm ⁻¹ , that is, the size of the absorption peak of OH ⁻ confirmed in the vicinity of 3620 cm ⁻¹ . Specifically, the smaller the minimum value of infrared transmittance in the vicinity of 3620 cm ⁻¹ , the greater the amount of moisture remaining in the glass composition. 5, to facilitate check the minimum value of the infrared transmittance near 3620 cm ^-1, in which the measurement results of infrared transmittance was enlarged in the wavelength range of 3600cm ^-1 ~3800cm ^-1.

In Comparative Examples 1 to 5, the infrared transmittance near 3620 cm ⁻¹ is relatively high at 7.8 to 8.0%. This is because H ₃ BO ₃ is not added and the residual amount of water in the glass composition is small. However, since H ₃ BO ₃ is not added in Comparative Examples 1 to 5, a desired clarification effect cannot be obtained, and a large amount of bubbles remain in the glass composition. Therefore, it is not suitable for a lamp.
In Comparative Examples 6 and 7, since the amount of H ₃ BO ₃ added is large, the residual amount of water in the glass composition is large, and the infrared transmittance near 3620 cm ⁻¹ is 2%. Thus, when there is much moisture remaining in a glass composition, since refoaming will occur at the time of heat processing, it is unsuitable for lamps.

In Comparative Example 8, both B ₂ O ₃ and H ₃ BO ₃ are added. However, since the mixing ratio of B ₂ O ₃ / H ₃ BO ₃ is smaller than 1/3, the residual amount of water in the glass composition is large, and the infrared transmittance near 3620 cm ⁻¹ is 2%. Thus, when there is much moisture remaining in a glass composition, since refoaming will occur at the time of heat processing, it is unsuitable for lamps.
In Comparative Example 9, both B ₂ O ₃ and H ₃ BO ₃ are added. However, since the mixing ratio of B ₂ O ₃ / H ₃ BO ₃ is larger than 1, the clarification effect is insufficient, and a large amount of bubbles remain in the glass composition, which is not suitable for lamps.

In Examples 1 to 3, B ₂ O ₃ and H ₃ BO ₃ are added at a mixing ratio in the range of 1/3 to 1. Therefore, the clarification effect is high and there are few bubbles in the glass composition. Further, the infrared transmittance in the vicinity of 3620 cm ⁻¹ is in the range of 3.0 to 4.5%, and the residual amount of water in the glass composition is small, and re-foaming is difficult to occur during heat processing. Therefore, it is suitable for lamps.

  The method for producing a glass composition for a lamp, the glass composition for a lamp and a lamp according to the present invention can be widely used for all lamps. In particular, it is suitable for a cold cathode fluorescent lamp of a backlight of a transmissive liquid crystal display element that requires a high-quality display such as a liquid crystal TV, a personal computer display, an in-vehicle liquid crystal panel, and the like. In addition, the method for producing a glass composition for lamps, the glass composition for lamps and the lamp according to the present invention substantially does not contain environmentally hazardous substances such as arsenic, antimony, lead, etc. -It can also respond to

  The present invention relates to a method for producing a glass composition for a lamp, a glass composition for a lamp produced using this method, and a lamp produced using this glass composition for a lamp.

  In general, a fluorescent lamp is used as a light source in a backlight of a transmissive liquid crystal display element such as a liquid crystal TV or a personal computer display. The fluorescent lamp for backlight has basically the same configuration as the fluorescent lamp for general illumination, but the tube diameter of the glass bulb is smaller and the wall thickness is thinner. Therefore, a borosilicate hard glass (hereinafter simply referred to as “borosilicate glass”) having high mechanical strength and excellent electrical insulation is used for such a fluorescent lamp for backlight.

  By the way, when air bubbles are present in the glass of the glass bulb, the mechanical strength of the glass bulb is reduced and breakage is likely to occur. Such a decrease in strength becomes a serious problem particularly in a glass bulb having a small tube diameter and a small thickness. Therefore, conventionally, arsenic or antimony is added to glass as a fining agent, and bubbles are removed from the glass (glass is clarified).

However, arsenic and antimony are environmentally hazardous substances that adversely affect the environment. Therefore, glass added with arsenic or antimony is not suitable for recycling. In addition, arsenic and antimony-added glass require careful handling in manufacturing factories and waste disposal factories, and require a large amount of equipment for detoxifying the etching waste liquid.
In order to cope with this type of problem, Patent Document 1 discloses a method for producing glass in which an effective amount of a salt containing SO ₃ , Cl 2 and F as a fining agent is added. With this method, it is possible to obtain a glass with less bubbles without adding an environmental load substance. It is also known that a clarification effect can be obtained by adding nitrates such as NaNO ₃ and KNO ₃ to glass.
JP 2004-284949 A

However, in the manufacturing method of Patent Document 1, gas harmful to the human body such as sulfide gas and halogen gas is generated in the glass melting step. Generation | occurrence | production of such noxious gas is unpreferable in order to deteriorate the working environment of glass manufacture.
Also, the addition of nitrate is not preferable because nitric acid gas (NOx) harmful to the human body is generated and the working environment of glass production is deteriorated.

  The objective of this invention is providing the manufacturing method of the glass composition for lamps which can manufacture glass with few remaining bubbles, without producing | generating harmful gas. Another object of the present invention is to provide a lamp glass composition with few bubbles that can be produced without generating harmful gases, and a lamp that is made of the glass composition for lamps and is less likely to break. There is.

In order to achieve the above object, a method for producing a glass composition for a lamp according to an embodiment of the present invention is characterized in that an oxide of a predetermined element and a hydroxide of the predetermined element are oxide / hydroxide = 1 / Including a melting step of melting a raw material mixture added at a molar ratio of 3 to 1 into a glass state, and in the melting step, H ₂ O or H ₂ is converted from the hydroxide by a decomposition reaction of the hydroxide. The raw material mixture is heated so that at least one gas is generated.

A glass composition for a lamp according to an embodiment of the present invention is a glass composition for a lamp produced by the above method for producing a glass composition for a lamp, and has a minimum value of infrared transmittance in the vicinity of a wavelength region of 3620 cm ^−1. Is 3.0 to 4.5% at a sample thickness of 2 mm.
The lamp | ramp which concerns on one Embodiment of this invention is equipped with the glass bulb | ball formed with the said glass composition for lamps, It is characterized by the above-mentioned.

In the method for producing a glass composition for a lamp according to the present invention, a gas composed of at least one of H ₂ O and H ₂ is generated from a hydroxide of a predetermined element in the melting step, so that bubbles are generated without generating harmful gas. It has the effect that a glass with a small amount can be produced. The effect will be described in detail below.
As a result of various studies, the inventors have replaced the oxide of the predetermined element added to the raw material mixture with the hydroxide of the predetermined element, thereby melting the raw material mixture into a glass state. In the process, it was found that gas was generated from the hydroxide, and bubbles in the glass melt were removed by the gas, and a clarification effect was obtained. Gas generated from the hydroxide is for generating the decomposition reaction of the hydroxide, of at least one of H ₂ O or H _2. A clarification effect is obtained by the decomposition reaction of the hydroxide occurring in a temperature range of 500 to 1000 ° C. at which the vitrification reaction is started.

In the first place, the bubbles present in the glass are those in which a gas such as CO ₂ generated when the raw material mixture is melted into the glass state remains without being completely removed from the glass melt. In particular, the bubbles of CO ₂ have a small diameter, have a low buoyancy, and are difficult to float from the glass melt, and therefore cannot easily escape from the glass melt and remain in the glass.
In order to remove such small-diameter bubbles, in the method for manufacturing a glass for a lamp according to the present invention, a gas composed of H ₂ O or H ₂ is generated from a hydroxide of a predetermined element. Since the gas bubbles made of H ₂ O and H ₂ have a larger diameter than bubbles such as CO ₂ , the buoyancy is larger, and the bubbles easily escape from the glass melt and hardly remain in the glass. The gas bubbles composed of H ₂ O and H ₂ take in bubbles such as CO ₂ when they rise from the glass melt, so that small-sized bubbles composed of CO _{2 and the} like are also removed from the glass.

However, when a gas composed of H ₂ O or H ₂ is generated in the glass melt, there is a problem that moisture tends to remain in the glass. If the amount of water remaining in the glass is large, the water vaporizes when heated, and refoaming (reboiling) is likely to occur. When a lamp is manufactured from such glass, it is reheated to a part that has been overheated by a burner or the like during heat processing. Foaming can cause slow leaks and cracks.

In response to this problem, the present inventors may make refoaming difficult to occur while sufficiently obtaining a clarification effect by defining the mixing ratio of oxide and hydroxide in the range of 1/3 to 1. I found it possible.
When the mixing ratio is greater than 1, the clarification effect is insufficient because the amount of gas composed of H ₂ O and H ₂ is small. On the other hand, when the mixing ratio is less than 1/3, re-foaming is likely to occur during heat processing, which is not suitable for a lamp.

As the predetermined element, boron (B), aluminum (Al), calcium (Ca) and the like can be considered, and in this case, the hydroxide of the predetermined element is H ₃ BO ₃ , Al (OH) ₃ and Means Ca (OH) ₂
The hydroxide according to the present invention includes not only a narrowly defined hydroxide, that is, a compound having a hydroxyl group, but also a broadly defined hydroxide, that is, a compound having a hydrogen element and an oxygen element. For example, not only narrow hydroxides such as Al (OH) ₃ and Ca (OH) ₂ , but also broad hydroxides such as H ₃ BO ₃ (which can be expressed as B (OH) ₃ ) Including.

The method for producing a glass composition for a lamp according to the present invention is such that the oxide and hydroxide are such that the content of the predetermined element in the glass composition for a lamp is 8 to 17 mol% in terms of oxide. When added to the mixture, it is possible to obtain a glass composition for a lamp which has good meltability and sealing property of the lead-in wire and hardly causes phase separation.
The method for producing a glass composition for a lamp according to the present invention is such that the hydroxide is such that the content of the predetermined element in the glass composition for a lamp is 5 to 10.5 mol% in terms of oxide. When added to the lamp, it is possible to obtain a glass composition for a lamp in which there are few bubbles and re-foaming hardly occurs during heat processing.

In the method for producing a glass composition for a lamp according to the present invention, the clarification effect is particularly remarkable when the glass composition for a lamp is borosilicate glass and the predetermined element is boron. For example, H ₃ BO ₃ which is a hydroxide of boron generates a gas composed of at least one of H ₂ O or H ₂ by a decomposition reaction in a wide temperature range of 300 to 800 ° C., so that temperature control is performed in the melting process. Is easy. The decomposition reaction of H ₃ BO ₃ is represented by the following (formula 1) and (formula 2).

2H ₃ BO ₃ → 3H ₂ O + B ₂ O ₃ (Formula 1)
2H ₃ BO ₃ → 3 / 2O ₂ + 3H ₂ + B ₂ O ₃ (Formula 2)
Furthermore, there is an effect that glass can be manufactured at low cost by using inexpensive H ₃ BO ₃ , and an effect that glass is not colored even if H ₃ BO ₃ is added in a large amount.
In the present invention, the borosilicate glass is a glass having a high Young's modulus and Vickers hardness and excellent mechanical strength, and specifically contains ₆ to 20 mol% of B ₂ O _{3 in} terms of oxide. Means glass.

Lamp glass composition according to the present invention, when the thermal expansion coefficient (α _30/380) of ^{34 × 10 -7 / K~43 × 10} -7 / K, or, 43 × 10 ^-7 / K~55 The following effects are obtained when × 10 ^-7 / K.
Generally, a lead lamp made of tungsten or Kovar alloy that can withstand high temperatures caused by discharge is used for a backlight lamp. Therefore, in order to increase the reliability of the hermetic seal of the lead-in wire, it is preferable to make the thermal expansion coefficient of the glass composition for lamps close to the thermal expansion coefficient of tungsten or Kovar alloy.

When the thermal expansion coefficient (α _30/380 ) is 34 × 10 ⁻⁷ / K to 43 × 10 ⁻⁷ / K, it is similar to the thermal expansion coefficient of the tungsten lead wire and has high chemical durability. The reliability of the airtight seal of the lead-in line is high.
When the coefficient of thermal expansion (α _30/380 ) is 43 × 10 ⁻⁷ / K to 55 × 10 ⁻⁷ / K, it is the same as the coefficient of thermal expansion of the Kovar alloy lead wire and has high chemical durability. The reliability of the airtight seal of the lead-in line is high.
The lamp | ramp which concerns on this invention is equipped with the glass bulb | ball formed with the said glass composition for lamps. Therefore, there are few bubbles in the glass of the glass bulb, and the lamp is not easily damaged.

A glass composition for a lamp, a method for producing a glass composition for a lamp, and a lamp according to an embodiment of the present invention will be described with reference to the drawings.
(Description of glass composition for lamp)
The composition of the glass composition according to the present embodiment is as shown in Examples 1 to 5 in FIG. Note that “%” in FIG. 1 means “mol%”.

The composition of the glass composition according to the present invention is not limited to the compositions shown in Examples 1 to 5, but in order to maintain the characteristics as a glass composition for a lamp, it is substantially SiO _{2 in} terms of oxide. _{: 55~75mol%, Al 2 O 3} : 1~10mol%, B 2 O 3 + H 3 BO 3: 8~17mol%, Li 2 O + Na 2 O + K 2 O: 0~12mol%, Li 2 _{O: 0~5mol%, Na 2 O} : 0~8mol%, K 2 O: 0~12mol%, MgO: 0.5~5mol%, CaO: 0.5~10mol%, SrO: 0~8mol%, BaO: 0~ _{10mol%, CeO 2: 0.01~2mol%} , Fe 2 O 3: 0~0.2mol%, SnO: is preferably 0.01 to 5 mol%.

In the present embodiment, the boron (B) contained in the glass composition includes those added to the raw material mixture as boron oxide and those added to the raw material mixture as boron hydroxide. However, in order to distinguish between them, “B ₂ O ₃ ” is used for those added as oxides, and “H ₃ BO ₃ ” is used for those added as hydroxides. These are the same in FIG. 1 and FIG. 3 described later.

Therefore, in the above, the meaning described as B ₂ O ₃ + H ₃ BO ₃ : 8 to 17 mol% means the total amount of boron added as an oxide and boron added as a hydroxide in the glass composition. The value in terms of oxide is 8 to 17 mol%.
The reason for determining the glass composition for a lamp of the present invention as described above is as follows.
SiO ₂ is a component that forms a glass skeleton, and its content is preferably in the range of 55 to 75 mol%. If it is less than 55 mol%, the coefficient of thermal expansion becomes too high and the chemical durability deteriorates. On the other hand, if it exceeds 75 mol%, the coefficient of thermal expansion becomes too low and it becomes difficult to process and mold.

Al ₂ O ₃ is a component added for the purpose of improving the weather resistance and devitrification of glass, and its content is preferably in the range of 1 to 10 mol%. When the amount is less than 1 mol%, it is difficult to obtain the above action. On the other hand, if it exceeds 10 mol%, the meltability of the glass deteriorates. The content is particularly preferably 2 to 7 mol%.
B ₂ O ₃ is an essential component of this example that is added for the purpose of improving the meltability of glass, adjusting the expansion coefficient, and adjusting the viscosity.

H ₃ BO ₃ is an essential component of this example that is added for the purpose of improving the meltability of the glass, adjusting the expansion coefficient, adjusting the viscosity, and promoting the clarification effect.
B ₂ O ₃ + H ₃ BO ₃ is preferably in the range of 8 to 17 mol%. When B ₂ O ₃ + H ₃ BO ₃ is less than 8 mol%, the meltability of the glass deteriorates, and the viscosity and the expansion coefficient increase to make it difficult to seal the lead-in wire. On the other hand, if it exceeds 17 mol%, the glass undergoes phase separation, making it difficult to produce the glass. The total content is particularly preferably 10 to 16 mol%.

B ₂ O ₃ and H ₃ BO ₃ are added so as to have a molar ratio of B ₂ O ₃ / H ₃ BO ₃ = 1 / 3-1. When the molar ratio is less than 1/3, re-foaming occurs in the overheated portion by the burner during thermal processing of the fluorescent lamp, which causes slow leaks and cracks. On the other hand, if the molar ratio is greater than 1, the glass refining effect is insufficient.
Alkali metal oxides of Li ₂ O, Na ₂ O and K ₂ O are added for the purpose of reducing the viscosity of the glass and improving the melt processability. The content is preferably in the range of 0 to 10 mol%. If it exceeds 10 mol%, the thermal expansion coefficient of the glass becomes too large. In addition, since alkali components are easily eluted from the glass, when a fluorescent lamp is manufactured using the glass, the glass reacts with the phosphor or mercury to reduce the luminous flux of the fluorescent lamp. The content of each component is preferably Li ₂ O: 0 to 5 mol%, Na ₂ O: 0 to 8 mol%, and K ₂ O: 0 to 12 mol%.

  MgO and CaO alkaline earth metal oxides are added for the purpose of improving electrical insulation and chemical durability. The content of MgO is preferably in the range of 0.5 to 5 mol%, and the content of CaO is preferably 0.5 to 10 mol%. If MgO is less than 0.5 mol% or CaO is less than 0.5 mol%, the above object may not be achieved. On the other hand, when MgO is more than 5 mol% or when CaO is more than 10 mol%, the glass tends to devitrify.

SrO and BaO are added for the purpose of improving the meltability of the glass and the bulb processability when manufacturing the fluorescent lamp. The SrO content is preferably 0 to 8 mol%, and the BaO content is preferably 0 to 10 mol%. When SrO is more than 8 mol% or BaO is more than 10 mol%, the glass tends to devitrify.
CeO ₂ is added for the purpose of effectively absorbing ultraviolet rays and suppressing solarization. The content is preferably in the range of 0.01 to 2 mol%. If the amount is less than 0.01 mol%, the object cannot be achieved. If the amount is more than 2 mol%, devitrification of the glass occurs, making it difficult to produce a fluorescent lamp having a desired lamp luminous flux. The content is particularly preferably in the range of 0.01 to 1 mol%.

Fe ₂ O ₃ is added for the purpose of obtaining an ultraviolet absorption effect. The content is preferably in the range of 0 to 0.2 mol%. If it exceeds 0.2 mol%, the transmittance in the visible region is lowered, and therefore the luminous flux of the fluorescent lamp is lowered, which is not preferable.
SnO is added for the purpose of promoting the valence change of Ce ions from 4+ to 3+. The content is preferably in the range of 0.01 to 5 mol%. If the amount is less than 0.01 mol%, the effect cannot be obtained. If the amount is more than 5 mol%, the mechanical strength of the glass is lowered and the yield is lowered in the glass tube drawing process. The range of 0.1 to 3 mol% is particularly preferable.

In addition, the glass which concerns on this invention should just contain the content rate of each component in said range substantially, and the other component may be contained in the limit which does not deviate from the range of the said composition. Examples of other components include ZrO ₂ , ZnO, P ₂ O ₅ , TiO ₂ , and WO ₃ .
Conventionally, CeO ₂ is known as one of the fining agents, but the fining effect cannot be obtained unless a large amount is added. However, if it is added in a large amount to obtain a clarification effect, a problem of coloring the glass occurs. Therefore, even when substantially only CeO ₂ is added as a clarifier, it is difficult to produce a glass that is colorless and has few remaining bubbles.

SnO _{2 is} also known as a fining agent, but as with CeO ₂ , a fining effect cannot be obtained unless a large amount is added. However, if a large amount is added to obtain a clarification effect, a problem that the glass devitrifies occurs. Therefore, even if only SnO ₂ is substantially added as a fining agent, it is difficult to produce a glass with no devitrification and few remaining bubbles.
(Description of manufacturing method of glass composition for lamp)
In the method for producing a lamp glass composition according to this embodiment, first, a plurality of types of glass raw materials are prepared within the range of the composition of the lamp glass composition according to the present invention to obtain a raw material mixture. Next, the raw material mixture is put into a glass melting furnace and melted at 1500-1600 ° C. for 5-8 hours in an air atmosphere to obtain a glass melt. At that time, treatments such as stirring and bubbling are not performed. Thereafter, the glass melt is formed into a tubular shape by a tube drawing method such as the Danner method, and cut into a predetermined size to obtain a glass tube for a lamp. Furthermore, the glass tube is heat-processed to produce a glass bulb, and various lamps are produced.

In addition, it is not limited to the procedure which mix | blends a glass raw material and makes it a raw material mixture, and throws into a glass melting kiln, A part of glass raw material is thrown into a glass melting kiln at a different timing from other glass raw materials, and glass melting It is also conceivable to prepare the raw material mixture in the kettle.
(Lamp description)
As an embodiment of the lamp according to the present invention, a straight tube type cold cathode fluorescent lamp will be described with reference to the drawings. FIG. 2 is a schematic view showing a main configuration of the cold cathode fluorescent lamp according to the present embodiment. The structure of the cold cathode fluorescent lamp 1 basically conforms to the structure of the cold cathode fluorescent lamp according to the prior art.

  The glass bulb 2 of the cold cathode fluorescent lamp 1 is formed by the lamp glass composition according to the present embodiment, and has an outer diameter of about 4.0 mm, an inner diameter of about 3.0 mm, and an overall length of about 730 mm. It is. The outer diameter, inner diameter, and overall length of the glass bulb 2 are not limited to the above. However, since the glass bulb 2 for the cold cathode fluorescent lamp 1 is desired to have a small tube diameter and a small thickness, the outer diameter is 1.8. The inner diameter is preferably 1.4 to 6.0 (inner diameter is 5.0) mm.

  Both ends of the glass bulb 2 are hermetically sealed with bead glass 3. Further, at both ends of the glass bulb 2, lead wires 4 made of tungsten metal or Kovar alloy having a diameter of about 0.8 mm are hermetically sealed so as to penetrate the bead glass 3. Then, a nickel or niobium cup-shaped electrode 5 whose surface is coated with an electron radioactive substance is attached to an end portion of each lead-in wire 4 on the inner side of the glass bulb 2.

On the inner surface of the glass bulb 2, a rare earth phosphor (Y ₂ O ₃ : Eu ³⁺ , LaPO ₄ : Ce ³⁺ , Tb ³⁺ , BaMg ₂ Al, which is a mixture of red, green and blue-green phosphors) _A phosphor layer 6 formed by coating ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ ) is formed. Further, 0.8 to 2.5 mg of mercury (not shown) and a rare gas such as xenon (not shown) are sealed inside the glass bulb 2.
As mentioned above, although the straight tube | pipe type cold cathode fluorescent lamp 1 which concerns on this invention has been concretely demonstrated based on embodiment, the content of this invention is not limited to said embodiment.

(Explanation of experiment)
A glass composition for a lamp according to the present embodiment shown in FIG. 1 and a glass composition for a lamp according to a comparative example shown in FIG. 3 were prepared, and their characteristics were evaluated and compared.
Each glass composition was prepared by weighing 17 g of the raw material mixture adjusted to the composition shown in the figure, putting it in a platinum crucible and heating and melting it at 1500 ° C. for 3 hours in an electric furnace, and then taking it out from the electric furnace, Was made by contacting with cold water and quenching, and peeling the interface between the glass and the crucible.

The coefficient of thermal expansion (α _30/380 ) and glass transition point were obtained by molding each glass composition into a cylindrical shape with a diameter of 5.0 mm and a length of 15 mm, and a thermomechanical analyzer (manufactured by Rigaku, model number: TAS300 TMA8140C) The average linear expansion coefficient in the temperature range of 30 to 380 ° C. was measured.
The number of bubbles was counted using image processing software for the number of bubbles confirmed in the central part of the cross section of the glass composition 120 mm ² and the plate thickness 3 mm. Only bubbles having a diameter of 30 μm or more were counted as bubbles.

The number of bubbles is cut to 120 mm ² (10 mm x 12 mm) and 3 mm thick at the center of the cross section of the glass composition, and then both sides of the glass are graded to # 400, # 800, # 1000, # 1500, and # 2000 Was polished and finished to a mirror surface to make a glass sample. The number of bubbles confirmed in the glass sample was counted using image processing software. Only bubbles having a diameter of 30 μm or more were counted as bubbles.

In the remaining bubble determination, a case where the number of bubbles exceeded 350 was determined as “×”, and a case where the number of bubbles was 350 or less was determined as “◯”. This is because it has been confirmed that when a lamp is produced with a glass composition having more than 350 bubbles, a significant decrease in yield occurs.
Re-foaming at the time of heat processing, when the glass composition is heat-processed, if a bubble having a diameter of 30 μm or more occurs in the overheated portion, it is judged as “×” with re-foaming, and when re-foaming does not occur, "".

Infrared transmittance was measured in a wavelength range of 2800 to 3800 cm ⁻¹ for a glass composition having a sample thickness of 2 mm with both surfaces mirror-polished using FT-IR (FTIR-8200 manufactured by Shimadzu Corporation). When evaluating an actual bulb, a glass plate having a thickness of 2 mm was produced by treating the glass bulb with a softening point of + 20 ° C. for 3 hours to soften the bulb. Thereafter, the glass plate was cut into a square of 15 mm length × 15 mm width to obtain a sample for evaluation of 15 mm length × 15 mm width × 2 mm thickness. Both surfaces of the sample for evaluation were polished step by step up to # 400, # 800, # 1000, # 1500, and # 2000, and finished to mirror surfaces.

The measurement results are shown in FIG. The infrared transmittance was performed for the purpose of evaluating the amount of water remaining in the glass composition. The moisture remaining in the glass composition is generated by the decomposition reaction of H ₃ BO ₃ , and a part of the moisture is dissolved in the glass composition. If the amount of water dissolved in the glass composition is large, the water dissolved when the glass composition is heat-processed is gasified and re-foaming occurs.
The amount of water in the glass composition can be confirmed by the minimum value of infrared transmittance in the vicinity of 3620 cm ⁻¹ , that is, the size of the absorption peak of OH ⁻ confirmed in the vicinity of 3620 cm ⁻¹ . Specifically, the smaller the minimum value of infrared transmittance in the vicinity of 3620 cm ⁻¹ , the greater the amount of moisture remaining in the glass composition. 5, to facilitate check the minimum value of the infrared transmittance near 3620 cm ^-1, in which the measurement results of infrared transmittance was enlarged in the wavelength range of 3600cm ^-1 ~3800cm ^-1.

In Comparative Examples 1 to 5, the infrared transmittance near 3620 cm ⁻¹ is relatively high at 7.8 to 8.0%. This is because H ₃ BO ₃ is not added and the residual amount of water in the glass composition is small. However, since H ₃ BO ₃ is not added in Comparative Examples 1 to 5, a desired clarification effect cannot be obtained, and a large amount of bubbles remain in the glass composition. Therefore, it is not suitable for a lamp.
In Comparative Examples 6 and 7, since the amount of H ₃ BO ₃ added is large, the residual amount of water in the glass composition is large, and the infrared transmittance near 3620 cm ⁻¹ is 2%. Thus, when there is much moisture remaining in a glass composition, since refoaming will occur at the time of heat processing, it is unsuitable for lamps.

In Comparative Example 8, both B ₂ O ₃ and H ₃ BO ₃ are added. However, since the mixing ratio of B ₂ O ₃ / H ₃ BO ₃ is smaller than 1/3, the residual amount of water in the glass composition is large, and the infrared transmittance near 3620 cm ⁻¹ is 2%. Thus, when there is much moisture remaining in a glass composition, since refoaming will occur at the time of heat processing, it is unsuitable for lamps.
In Comparative Example 9, both B ₂ O ₃ and H ₃ BO ₃ are added. However, since the mixing ratio of B ₂ O ₃ / H ₃ BO ₃ is larger than 1, the clarification effect is insufficient, and a large amount of bubbles remain in the glass composition, which is not suitable for lamps.

In Examples 1 to 3, B ₂ O ₃ and H ₃ BO ₃ are added at a mixing ratio in the range of 1/3 to 1. Therefore, the clarification effect is high and there are few bubbles in the glass composition. Further, the infrared transmittance in the vicinity of 3620 cm ⁻¹ is in the range of 3.0 to 4.5%, and the residual amount of water in the glass composition is small, and re-foaming is difficult to occur during heat processing. Therefore, it is suitable for lamps.

  The method for producing a glass composition for a lamp, the glass composition for a lamp and a lamp according to the present invention can be widely used for all lamps. In particular, it is suitable for a cold cathode fluorescent lamp of a backlight of a transmissive liquid crystal display element that requires a high-quality display such as a liquid crystal TV, a personal computer display, an in-vehicle liquid crystal panel, and the like. In addition, the method for producing a glass composition for lamps, the glass composition for lamps and the lamp according to the present invention substantially does not contain environmentally hazardous substances such as arsenic, antimony, lead, etc. -It can also respond to

The composition and characteristic of the glass composition concerning one embodiment of the present invention are shown. It is the schematic which shows the principal part structure of the cold cathode fluorescent lamp concerning one Embodiment of this invention. The composition and characteristic of the glass composition which concerns on a comparative example are shown. It shows the infrared transmittance at a range of 2800cm ^-1 ~3800cm ^-1 glass composition according to one embodiment of the present invention. It shows the infrared transmittance at a range of 3600cm ^-1 ~3800cm ^-1 glass composition according to one embodiment of the present invention.

Explanation of symbols

  1 lamp

Claims (14)

A melting step of melting a raw material mixture in which an oxide of a predetermined element and a hydroxide of the predetermined element are added at a molar ratio of oxide / hydroxide = 1/3 to 1 into a glass state;
In the melting step, the raw material mixture is heated so that a gas composed of at least one of H ₂ O or H ₂ is generated from the hydroxide by a decomposition reaction of the hydroxide. A method for producing the composition.   2. The oxide and hydroxide are added to the raw material mixture so that the content of the predetermined element in the lamp glass composition is 8 to 17 mol% in terms of oxide. The manufacturing method of the glass composition for lamps of this.   The said hydroxide is added to the said raw material mixture so that content of the said predetermined element in the glass composition for lamps may be 5-10.5 mol% in conversion of an oxide. A method for producing a glass composition for a lamp.   4. The method for producing a glass composition for a lamp according to claim 3, wherein the glass composition for a lamp is borosilicate glass, and the predetermined element is boron.   The said hydroxide is added to the said raw material mixture so that content of the said predetermined element in the glass composition for lamps may be 5-10.5 mol% in conversion of an oxide. A method for producing a glass composition for a lamp.   The method for producing a glass composition for a lamp according to claim 1, wherein the glass composition for a lamp is borosilicate glass, and the predetermined element is boron. A glass composition for a lamp produced by the method for producing a glass composition for a lamp according to claim 1,
A glass composition for a lamp, wherein a minimum value of infrared transmittance in the vicinity of a wavelength region of 3620 cm ⁻¹ is 3.0 to 4.5% at a sample thickness of 2 mm. Thermal expansion coefficient at 30~380 ℃ (α _30/380) is ^{34 × 10 -7 / K~43 × 10} -7 / K lamp glass composition according to claim 7, characterized in that the. Thermal expansion coefficient at 30~380 ℃ (α _30/380) is ^{43 × 10 -7 / K~55 × 10} -7 / K lamp glass composition according to claim 7, characterized in that the. A glass composition for a lamp produced by the method for producing a glass composition for a lamp according to claim 4,
A glass composition for a lamp, wherein a minimum value of infrared transmittance in the vicinity of a wavelength region of 3620 cm ⁻¹ is 3.0 to 4.5% at a sample thickness of 2 mm. Thermal expansion coefficient at 30~380 ℃ (α _30/380) is ^{34 × 10 -7 / K~43 × 10} -7 / K lamp glass composition according to claim 10, characterized in that a. Thermal expansion coefficient at 30~380 ℃ (α _30/380) is ^{43 × 10 -7 / K~55 × 10} -7 / K lamp glass composition according to claim 10, characterized in that a.   A lamp comprising a glass bulb formed of the glass composition for a lamp according to claim 7.   A lamp comprising a glass bulb formed from the glass composition for a lamp according to claim 10.

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