WO2009090965A1

WO2009090965A1 - Ionizer

Info

Publication number: WO2009090965A1
Application number: PCT/JP2009/050398
Authority: WO
Inventors: Kenichi Kobayashi; Takeshi Manabe; Akira Morishige
Original assignee: Tokai Industry Corp.
Priority date: 2008-01-15
Filing date: 2009-01-14
Publication date: 2009-07-23

Abstract

Disclosed is an ionizer that is suitable for use, for example, in clean rooms and generates little or no dust. The ionizer comprises at least one discharge electrode for applying a high voltage to air to ionize the air and thus to generate ions and a power supply part for supplying electric power to the discharge electrode. The ionizer is characterized in that at least a part of the discharge electrode is formed of an electroconductive vanadate glass obtained by a process in which an electroconductive vanadate glass obtained by preparing a mixture containing a vanadate, then melting the mixture and rapidly cooling the mixture, or an electroconductive vanadate glass obtained by further annealing the glass is immersed in an aqueous liquid medium.

Description

Ionizer

The present invention relates to an ionizer (static eliminating device) for neutralizing the charge of a charged body that is positively or negatively charged, and more particularly to a low dusting ionizer.

Due to recent technological development advances, integrated circuits have significantly increased the degree of integration. However, as the degree of integration of an integrated circuit increases, the line width of the circuit becomes very small, which is easily affected by external influences in the manufacturing process, and the yield is deteriorated. In particular, when floating particles such as dust adhere to the circuit, the circuit is disconnected or short-circuited. Therefore, in LSI factories and electronic device assembly factories, the entire factory or a part of the factories is used as a clean room to reduce suspended fine particles in the factory as much as possible. However, static electricity is likely to be generated in the clean room because it is kept at low humidity (about 40-45% RH) in order to suppress product deterioration and prevent the growth of microorganisms. For example, static electricity is generated in people, facilities, and the like due to factors such as the movement of people in the clean room and the flow of air (wind). In addition, in order to prevent dust generation and improve chemical resistance, a lot of insulators such as plastics are used, which makes the environment more susceptible to static electricity. When static electricity is generated, a wafer provided with a circuit is charged and a small amount of fine particles remaining in the clean room are sucked, resulting in deterioration of quality. In addition, the circuit on the wafer may be destroyed by the discharge. Furthermore, there is a possibility that the manufacturing apparatus or the computer may malfunction due to electromagnetic waves, or the work efficiency of the worker may be reduced due to electric shock.

In order to prevent such static electricity failure, the static electricity generated in the clean room must be removed. The first possible method for removing static electricity is to ground the charged object and remove the static electricity for each object. It is. However, since this method is effective only when the equipment is conductive and fixed, a plurality of independent objects such as wafers and carriers that carry them are transported one after the other. It is difficult to take a way to escape.

Therefore, conventionally, there is a method of neutralizing static electricity by ionizing and ionizing air in a clean room, instead of discharging each individual object like grounding. This static elimination method by air ionization is suitable for static elimination in a clean room because it can neutralize a wide area without contacting a charged object. As methods for ionizing air, those using corona discharge, radiation, ultraviolet rays, and the like are known. Among them, the method using corona discharge is widely used because it is safer and cheaper than other methods. ing.

A clean room ionizer has been conventionally proposed as a device for neutralizing static electricity on an object surface by ionizing air by such corona discharge. This clean room ionizer is composed of a plurality of ionizer electrodes provided on the ceiling of the clean room and a device for applying a voltage to the ionizer electrodes. And the ionizer for clean rooms which has such a structure generate | occur | produces ion by the corona discharge which arises when a high voltage is applied to an ionizer electrode, and neutralizes static electricity by this ion (patent document 1).
JP-A-6-325894

However, in the conventional clean room ionizer, the electrode of the ionizer itself has a dust generating property, which causes problems such as a decrease in the cleanliness of the air in the clean room. Accordingly, an object of the present invention is to provide an ionizer that is suitable for use in a clean room and has little or no dust generation.

The present invention (1) is a conductive vanadate glass obtained by melting and quenching after preparing a mixture containing a vanadate, or a conductive vanadate glass that has been further annealed. It is a discharge electrode that is at least partially composed of conductive vanadate glass obtained by the step of immersing in an aqueous liquid medium.

The present invention (2) includes at least one discharge electrode (for example, the discharge electrode 3) for generating ions by applying a high voltage to air to ionize,
A power supply unit (for example, power supply 1) for supplying power to the discharge electrode;
In an ionizer having
The discharge electrode is an ionizer which is the discharge electrode (for example, discharge electrode 3) of the invention (1).

Here, the meaning of each term in this specification is explained. First, “conductive glass” means that the electric conductivity is at least 1 × 10 ⁻¹³ S / cm (preferably at least 1 × 10 ⁻⁹ S / cm, more preferably at least 1 × 10 ⁻⁷ S / cm. ). Examples of the “conductive glass” include ion conductive glass, electron conductive glass, and mixed conductive glass in which the two types of conductivity coexist. The “ion-conducting glass” is not particularly limited. For example, AgI-Ag ₂ O—B ₂ O ₂ , AgI-Ag ₂ O—P ₂ O ₅ , AgI-Ag ₂ O—WO ₃ , LiCl—Li ₂ Examples thereof include glass containing O—B ₂ O ₃ or the like. Examples of the “electron conducting glass” include valence electron hopping conducting glass and band gap conducting glass. Although it does not specifically limit as a valence electron hopping conductive glass, The glass containing a vanadate is mentioned. The band gap conductive glass is not particularly limited, and examples thereof include chalcogenide glasses such as Ge—Te—S, Ge—Te—Se, and Ge—Te—Sb. The “mixed conduction type glass” is not particularly limited, and examples thereof include glass containing vanadate, AgI and AgO ₂ (see JP 2004-331416 A) and Li _x WO ₃ . Among these, glass containing vanadate is particularly preferable because of its high conductivity. The “discharge needle” is not particularly limited as long as it has conductive glass at its tip. For example, a member made only of conductive glass or a composite member having conductive glass only at the tip may be on the surface of another material. It may be a composite member coated with conductive glass.

According to the ionizer according to the present invention, there is an effect that dust generation of the discharge electrode itself can be minimized. Furthermore, since the electrical conductivity of the conductive vanadate glass can be appropriately set by the content of vanadate and annealing, there is an effect that the amount of discharged ions can be easily adjusted.

Hereinafter, the best mode of the present invention will be described with reference to the drawings. The technical scope of the present invention is not limited to the best mode. In addition, it should be understood that the matters specifically described in one example can be applied to other examples as they are, unless otherwise specified.

Ionizer The ionizer according to the present invention is composed of at least one discharge electrode for generating ions by applying a high voltage to air, and a power supply unit for supplying power to the discharge electrode. The discharge electrode is obtained by immersing a conductive vanadate glass obtained by melting and quenching after preparing a raw material mixture or a conductive vanadate glass further annealed on the glass in an aqueous liquid medium. One feature is that it is a conductive vanadate glass obtained by the step. The power source can be applied to any type using either an AC power source or a DC power source. Furthermore, the power source is preferably a high voltage power source.

As an example of the configuration according to the best mode, an ionizer provided on the ceiling in the clean room will be described below as an example. That is, as shown in FIG. 1, the main body case 2 is provided on the power source 1 and the ceiling C of the clean room, and the discharge electrode 3 is provided in the main body case 2 so that at least the tip protrudes outside. The discharge electrode 3 is a member obtained by processing a lower end of a rod-shaped conductive glass into a conical shape, and the upper end thereof is connected to the power source 1. The configuration other than the discharge electrode is a conventional technique {for example, a blower type as disclosed in JP-A-2004-253193 and JP-A-2007-66822, and a bar as disclosed in JP-A-2007-141169. Type, gun type as disclosed in Japanese Patent Application Laid-Open No. 2004-319358 can be applied as it is, and the following description will focus on the discharge electrode.

Conductive glass The ionizer according to the present invention is characterized in that a conductive vanadate glass subjected to a predetermined treatment is used as a discharge electrode. That is, the present invention uses a low dust-generating conductive glass in which powder is not deposited on the surface as a discharge electrode by immersing a conductive vanadate glass produced by a normal technique in an aqueous medium. Let it be the essence. As the discharge electrode according to the best mode, it is preferable to use a discharge needle having a sharp tip, and at least the discharge tip portion of the discharge electrode only needs to be made of the conductive vanadate glass. Here, the partial configuration of the discharge electrode other than the conductive vanadate glass is not particularly limited. For example, rare metals such as tungsten, titanium, and silicon, iron, and the like can be used. Therefore, first, each component constituting the conductive vanadate glass (untreated) before water treatment will be described, and then the properties of the conductive vanadate glass (untreated) will be described. The method for producing the conductive glass (untreated) will be described. Next, a method for producing a low dust-generating conductive vanadate glass and its properties will be described. In the following best mode, water will be described as an example of the aqueous liquid medium, but the present invention is not limited to this.

《Conductive vanadate glass (untreated)》
At least a part of the discharge electrode of the ionizer according to the best mode is made of conductive vanadate glass. The “conductive vanadate glass” is not particularly limited as long as it is a conductive glass containing vanadate, but is an oxide-based glass composition containing vanadium, barium and iron because it is highly conductive. Is preferred. Here, first, vanadium is a constituent element for forming the main skeleton of oxide-based glass, and its oxidation number changes to 2, 3, 4, 5, etc., to increase the probability that electrons hop. Can do. Next, barium is a constituent element added to make the glass skeleton of the vanadium oxide having a two-dimensional structure three-dimensional. Furthermore, iron is a component for adjusting electrical conductivity, and the conductivity can be controlled by changing this amount.

Here, the vanadium oxide content in the vanadate glass is preferably in the range of 0.1 to 98 mol%, more preferably in the range of 40 to 98 mol%. The content of barium oxide in the vanadate glass is preferably in the range of 1 to 40 mol%. The content of iron oxide in the vanadate glass is preferably in the range of 1 to 20 mol%. Furthermore, the molar ratio (B: V) of barium oxide (B) to vanadium oxide (V) is preferably 5:90 to 35:50. The molar ratio (F: V) of iron oxide (F) to vanadium oxide (V) is preferably 5:90 to 15:50.

Furthermore, the conductive vanadate glass may contain rhenium. Here, rhenium is excellent in electrical conductivity (and can further increase the electron hopping effect because the oxidation number can be changed), so that the electrical conductivity of the vanadate glass can be further increased. In addition, since the glass transition temperature and the crystallization temperature can be set within a predetermined range, the annealing process can be facilitated. When rhenium is contained, the amount in the composition is preferably 1 to 15 mol%.

Further, the conductive vanadate glass is composed of other glass components such as calcium oxide, sodium oxide, potassium oxide, barium oxide, boron oxide, strontium oxide, zirconium oxide, silver oxide, silver iodide, lithium oxide, iodine. Lithium iodide, cesium oxide, sodium iodide, indium oxide, tin oxide and the like may be contained.

The electrical conductivity of such vanadate glass is in the range of 10 ⁻⁴ to 10 ⁻¹ S · cm ⁻¹ , preferably 10 ⁻³ to 10 ⁻² S · cm ⁻¹ at a room temperature of 25 ° C. Is preferred. In particular, from the viewpoint of maintaining semiconductor characteristics, it is preferably 10 ⁻¹ S · cm ⁻¹ or less. Here, the electrical conductivity in this specification refers to the volume resistivity measured by the four probe method.

In addition, in order to dilute the base composition (vanadium, barium and oxide glass composition) of the conductive glass from the viewpoint of adjusting the electric conductivity, a diluted component {preferably, SiO ₂ is added to the composition. (60-70 mol%), P ₂ O ₃ (10-20 mol%), Al ₂ O ₃ (2-10 mol%), ZnO (0-2 mol%), Sb ₂ O ₃ (0-2 mol%) %), TiO ₂ (0 to 2 mol%)} may be added.

Here, the conductive vanadate glass is obtained by melting and quenching a mixture containing vanadium oxide, barium oxide and iron oxide (optionally rhenium oxide) to obtain the glass composition, and then the glass transition of the glass composition. Even if it is above the temperature, below the crystallization temperature, or above the crystallization temperature, it can be produced by keeping it at the annealing treatment temperature below the softening point temperature for a predetermined time.

For example, a mixture containing 50 to 90 mol% of vanadium oxide, 5 to 35 mol% of barium oxide, and 5 to 25 mol% of iron oxide (in some cases, 1 to 10 mass% of rhenium oxide is added to 100 mass% of the mixture) After being heated and melted in a platinum crucible or the like, it is rapidly cooled to be vitrified, and this vitrified product is heat-treated under predetermined annealing conditions.

<Low dusting conductive vanadate glass>
Furthermore, the vanadate glass to be used is a conductive vanadate glass obtained by preparing a mixture containing vanadium oxide and then melting and quenching, or a conductive vanadate glass obtained by further annealing the glass. Is immersed in an aqueous liquid medium (for example, water). In general, it is known that when a conductive vanadate glass is immersed in an aqueous liquid medium (for example, water) for a long time, a free layer may be formed on the surface due to a reaction between the glass surface and water or the like. . And when the said free layer was formed in electroconductive vanadate glass, in addition to reducing the electroconductivity of electroconductive glass remarkably, it was worried that the said free layer may become the cause of further dust. However, the present inventors have confirmed that it is possible to obtain a low dust conductive vanadate glass without lowering the electrical conductivity of the vanadate glass when carried out against the common sense. Here, the “aqueous liquid medium” refers to water (for example, pure water, water containing other components such as sodium chloride) (for example, tap water or seawater), alcohol, for example, ethanol, and a mixed liquid of water and alcohol. Examples thereof include a mixed liquid of ethanol and water. In addition, the “low dusting conductive vanadate glass” is different depending on the use when measured by a dusting measuring method according to JIS B 9920: 2002 (for example, using a Sysmex model 110). It refers to a glass having 0 dust of 1 μm or more (preferably 0 dust of 0.5 μm or more, more preferably 5 or less of 0.3 μm or more). The “annealing treatment” is not limited to the glass transition temperature or more and the crystallization temperature or less, but may be the crystallization temperature or more and the softening point temperature or less.

Here, the aqueous liquid medium treatment method will be described in more detail. The method includes a step of immersing a conductive vanadate glass (untreated) in water. The process according to the best mode may be performed after the glass composition is melted and rapidly cooled in the manufacturing process of the conductive vanadate glass, or may be performed after the annealing treatment. Further, it may be performed after processing into a discharge needle. Among these, it is particularly preferable to perform this step after processing into a discharge needle. By performing this step in this order, a discharge needle having a lower dust generation property can be obtained.

Specifically, a process is performed in which conductive vanadate glass is immersed in water, the water temperature is set to a predetermined temperature, and dust-derived components are dissolved in water for a predetermined time. Here, at the time of the immersion, it is preferable to apply a predetermined amount of electricity to the vanadate glass and / or perform ultrasonic treatment. By combining these, extraction of dust-derived components can be performed efficiently and in a short time.

Here, the temperature of the aqueous liquid medium is preferably 30 ° C. to the boiling point or less, and in the case of water, the water temperature is preferably 30 to 100 ° C., more preferably 40 to 70 ° C. The “boiling point” means a boiling point measured under normal pressure (1 atm). In the case of a mixed liquid that does not azeotrope, it refers to the boiling point of the lowest component among the components, and further, the mixed liquid that azeotropes. In the case of, it means an azeotropic point. In the case of supplying electricity, the power source may be alternating current or direct current, and is preferably 1 to 100 mA, more preferably 1 to 20 mA. Further, in the case where the process is carried out without passing an electric current in water, the treatment is preferably carried out for 1 to 2000 hours, more preferably 1 to 1500 hours. In the case where the treatment is performed while a current is applied, the treatment is preferably performed for 1 to 300 hours, more preferably for 1 to 150 hours. When performing ultrasonic treatment, the ultrasonic frequency is preferably 30 kHz to 4 MHz, more preferably 30 kHz to 3 MHz, and further preferably 30 to 80 kHz. The sonication time is preferably 1 to 30 hours, more preferably 1 to 10 hours, and further preferably 1 to 3 hours.

In addition, yellow powder adheres to the surface of the low dust generation conductive vanadate glass obtained immediately after the treatment, and this is wiped off and the obtained conductive vanadate glass is used.

When ultrasonic treatment is performed, a cavitation effect by ultrasonic waves can be obtained. The cavitation effect is due to the fact that the liquid is shaken vigorously by ultrasonic irradiation, and a locally high pressure portion and a low pressure portion are generated. This is a phenomenon in which shock waves are generated when the bubbles are crushed and burst. By performing the low dust generation treatment using the cavitation effect, the shock wave gives an impact to the sample, so that the dust-derived component can be extracted efficiently. Furthermore, the component deposited on the sample surface is prevented from sticking in layers due to the cleaning effect associated with the cavitation effect, and the operation proceeds smoothly.

The low dusting conductive vanadate glass thus obtained has a result obtained by the dusting measurement method described later, preferably 0 dust of 1 μm or more, and more preferably 0. The number of dusts of 0.5 μm or more is zero, and more preferably, the number of dusts of 0.3 μm or more is five or less. In addition, the electrical conductivity of the low dusting conductive vanadate glass according to the best mode is preferably 10 ⁻¹³ S · cm ⁻¹ or more at 25 ° C., and 10 ⁻⁹ S · cm ⁻¹ or more. Is more preferable, and 10 ⁻⁷ S · cm ⁻¹ or more is more preferable.

<< Discharge needle manufacturing method >>
Next, the manufacturing method of the discharge needle which consists of conductive glass which concerns on this best form is explained in full detail. First, a flat conductive glass mainly composed of vanadate is manufactured. Next, the flat conductive glass is polished by a polishing machine. At this time, it is preferable to use corundum, alundum (alumina), cerium oxide, colloidal silica or the like as the abrasive. In particular, corundum has a coarse particle size, and cerium oxide and colloidal silica are fine. Therefore, it is preferable to use the former in the initial stage and the latter in the mirror finishing stage. Next, the ground flat conductive glass is cut into a specified size. Then, the rectangular conductive glass is fixed to a diamond grinder, and is cut into a round bar with diamond while rotating around the long axis. At this time, the rotation speed is preferably 1000 to 6000 rpm. Then, the discharge needle can be manufactured by performing the operation of cutting the tip into a conical shape with the same diamond grinder.

The operation of this embodiment having the above-described configuration is as follows. That is, a voltage is applied from the power source 1 to the discharge electrode 3. Then, corona discharge is generated from the discharge electrode 3, and the air around the discharge electrode is ionized. The ionized air irradiates the charged substance, whereby the charged substance is neutralized.

Production Example 1 (conductive vanadate glass)
Mixtures each having a chemical composition adjusted to 15BaO · 70V ₂ O ₅ · 15FeO were prepared. The mixture was transferred to a platinum crucible or the like, heated in an electric furnace at 1000 ° C. for 60 minutes, and melted. This was immediately quenched with ice water (the outer side of the platinum crucible, the bottom was immersed in ice water) to obtain a conductive vanadate glass (electric conductivity: 7 × 10 ⁻³ S · cm ⁻¹ ). The glass was annealed at 400 ° C. for 1 hour to produce a conductive vanadate glass (electric conductivity: 7 × 10 ⁻³ S · cm ⁻¹ ) subjected to the following low dust generation treatment.

Measuring method of electric conductivity The electric conductivity was determined by a four-terminal method for conductive vanadate glass pieces having a thickness of 1 mm or less. Here, an electrode was prepared by fixing lead wires to the glass surface using molten metal indium. The value of electric conductivity (σ) is obtained by dividing the value of current density (Acm ⁻² ) by the magnitude of the electric field.
Acm ⁻² ÷ Vcm ⁻¹ = A / Vcm ⁻¹ = S / cm ⁻¹ = S · cm ⁻¹
The electrical conductivity (S · cm ⁻¹ ) is the reciprocal of the specific resistance (Ω · cm).

Method for Measuring Dust Generation The dust generation property of the conductive vanadate glass itself was measured using the measuring apparatus 100 shown in FIG. The measuring apparatus 100 includes a space 101 of 10 cm × 10 cm × 10 cm, a Y-shaped sample stage 102 made of a thin bar, and a particle counter connection hole 103 installed in the space 101. The particle counter connection hole 103 is connected to an air suction port of the particle counter 200 (Sysmex model 110).
The method for measuring dust generation is performed in the following steps (1) to (4).
Step (1): Sample A (3 mm × 3 mm × 40 mm rectangular parallelepiped shape) is washed with pure water (10 seconds) using absorbent cotton, and then sufficiently dried.
Step (2): After the step, the sample A is allowed to stand for 1 day under conditions of humidity 80% and 25 ° C.
Step (3): Leave at a temperature of 50 ° C. and a humidity of 0% for 1 hour.
Step (4): The space 100 is made sufficiently clean (class 1 in JIS B 9920: 2002), the sample A obtained by the above step is placed on the stage 102, and the particle counter connection hole 103 and After the sample A is placed at a distance of 1 cm, the air in the space 100 is sucked into the particle counter at a speed of 2.83 liters per minute, and in accordance with the method for measuring the number of particles in JIS B 9920: 2002, Division measurement is performed at 0.1 to 0.2 μm, 0.2 to 0.3 μm, 0.3 to 0.5 μm, 0.5 μm to 1.0 μm, 1.0 μm or more.
The number of tests is basically one time, but if a particle having a size of 1 μm or more cannot be confirmed even once, it is recognized as “low dust generation”.

Yellowing Measurement Method Yellowing measurement method is carried out in the following steps (1) to (3).
Step (1): Sample A (3 mm × 3 mm × 40 mm rectangular parallelepiped shape) is washed with pure water (10 seconds) using absorbent cotton, and then sufficiently dried.
Step (2): After the step, the sample A is allowed to stand for 1 day under conditions of humidity 80% and 25 ° C.
Step (3): The L ^* a ^* b ^* color system was measured according to JIS Z 8701.

Production Example 2 (Low dusting conductive vanadate glass)
The conductive vanadate glass obtained in Production Example 1 was immersed in tap water prepared in a sample bottle with a lid, and a low dust generation treatment was performed at room temperature for about two months. As a result, the yellow component was dissolved in water, and the entire water was dyed yellow. Thereafter, the conductive vanadate glass was taken out from the sample bottle, and the surface was washed away cleanly to obtain a low dusting conductive vanadate glass according to Production Example 2. The low dusting conductive vanadate glass was again immersed in tap water, but the yellow component did not elute in the water of the sample bottle for more than 2 months. The electrical conductivity of the low dusting conductive vanadate glass was not different from that of the conductive vanadate glass before treatment (electrical conductivity: 7 × 10 ⁻³ S · cm ⁻¹ ). The results of the dust generation test are shown in Table 1. The conductive vanadate glass before the treatment was observed to change in color (changed to yellow) before and after the dust generation test step (2). On the other hand, in the low dusting conductive vanadate glass after the treatment, no color change was observed before and after the step (2) of the dusting test (not changed to yellow).

Production Example 3 (Low dusting conductive vanadate glass)
The conductive vanadate glass obtained in Production Example 1 is soaked in water at 15 ° C., heated to 100 ° C., supplied with a current of 5 to 10 V and 1 to 5 mA, and has a low dust generation for 3 to 15 hours. After the treatment, the yellow component adhering to the surface was wiped off and washed away to obtain a low dusting conductive vanadate glass according to Production Example 3 (electric conductivity: 7 × 10 ⁻³ to 1 × 10 ⁻² S · cm ⁻¹ ). In addition, as a result of analyzing the yellow component adhering to the low dust generation / yellowing resistance conductive vanadate glass surface by XPS, the component adhering to the surface was C: 36.7, O: 46.7, V: 8.0, N: 1.4, S: 1.8, Fe: 1.8, Ba: 3.6 (atom%). 3 shows the state of the surface of the conductive vanadate glass before the treatment {FIG. 3 (a)} and the state of the surface of the low dusting conductive vanadate glass after the treatment {FIG. 3 (b). )}. The conductive vanadate glass before the treatment was observed to change in color (changed to yellow) before and after the dust generation test step (2). On the other hand, in the low dusting conductive vanadate glass after the treatment, no color change was observed before and after the step (2) of the dusting test (not changed to yellow).

Production Example 4 (Low dusting conductive vanadate glass)
300 cc of water was added to a washing machine having a transmission frequency of 40 kHz (Citizen ultrasonic washing machine SW7800), and the conductive vanadate glass produced in Production Example 1 was added thereto, followed by ultrasonic treatment for 5 minutes. As a result, dust was generated in water and turned yellow, and a dust-resistant conductive vanadate glass was obtained (electric conductivity 7 × 10 ⁻³ S · cm ⁻¹ ). The results of the dust generation test are shown in Table 1. The conductive vanadate glass before the treatment was observed to change in color (changed to yellow) before and after the dust generation test step (2). On the other hand, in the low dusting conductive vanadate glass after the treatment, no color change was observed before and after the step (2) of the dusting test (not changed to yellow).

Production Example 5 (Low dusting conductive vanadate glass)
1,000 cc of water was added to a washing machine (Alex ATL3022) having a transmission frequency of 72 kHz, and the conductive vanadate glass produced in Production Example 1 was added thereto, followed by sonication for 5 minutes. As a result, dust was generated in water and turned yellow, and a dust-resistant conductive vanadate glass was obtained (electric conductivity: 7 × 10 ⁻³ S · cm ⁻¹ ). The results of the dust generation test are shown in Table 1. The conductive vanadate glass before the treatment was observed to change in color (changed to yellow) before and after the dust generation test step (2). On the other hand, in the low dusting conductive vanadate glass after the treatment, no color change was observed before and after the step (2) of the dusting test (not changed to yellow).

Production Example 6 (Discharge needle)
The plate-shaped conductive vanadate glass member according to Production Example 2 was polished using a polishing machine. At this time, the smallest was a polishing material having a particle size of 500, and polishing was carried out in steps of 1500 and 2000 (the final number 2000 was mirror-finished with colloidal silica). In addition, the said grinding | polishing was implemented by pressing a plate glass, dripping the abrasive | polishing agent in the state disperse | distributed with water on the rotating lapping machine (both sides). At this time, each time was 30 minutes, and mirror finishing was performed until the flatness obtained an accuracy of ˜ ± 2 μm. And after cutting | disconnecting with a diamond cutter to 45 mm x 2.5 mm x 2.5 mm, the said square-shaped electrically conductive glass was fixed to the diamond grinder, and the front-end | tip conical discharge needle was created.

The discharge needle manufactured as described above was attached to the clean room ionizer shown in FIG. As a result, as shown in Table 2, it was found that the discharge needle can be suppressed to a dust generation amount of 1/2 or less as compared with other materials. The numerical values in the table are the number of particles of 0.1 μm or more. In addition, it was confirmed by the charge removal test that the charge was removed satisfactorily.

Subsequently, using the discharge needle manufactured in Production Example 6, the discharge characteristics of the discharge needle were examined. The results are shown in Table 3. Here, the evaluation was performed using a static eliminator described in FIG. 1 with a plate monitor (150 mm × 150 mm 20 pF, charge plate monitor H0601 manufactured by Sicid Electrostatics). The voltage is a voltage (kV) applied to the discharge needle. The application method indicates whether it is alternating current (AC) or direct current (DC), and the numerical value under AC means the frequency of AC. The current (μA) is a current that flows during discharge. Decay Time is the time required to neutralize a charged object charged to ± 1000 V to ± 100 V. The ion balance is a range of +/- bias. The temperature (° C.) is the temperature of the atmosphere during the discharge experiment, and the humidity (%) is the relative humidity of the atmosphere during the discharge. As a result, it was found that the discharge needle according to the best mode can be used as an ionizer because it exhibits good static elimination time and good ion balance regardless of whether it is alternating current or direct current. .

FIG. 1 is a conceptual diagram of a static eliminator according to the present invention. FIG. 2 is a conceptual diagram of the measuring apparatus. FIG. 3 shows the state of the surface of the conductive vanadate glass before the treatment according to the best mode {FIG. 3A} and the state of the surface of the low dusting conductive vanadate glass after the treatment {FIG. 3 It is the figure which showed (b)}.

Explanation of symbols

1: Power supply 2: Body case 3: Ionizer electrode C: Ceiling

Claims

A conductive vanadate glass obtained by melting and quenching after preparing a mixture containing vanadate or a conductive vanadate glass that has been further annealed is immersed in an aqueous liquid medium. A discharge electrode, at least part of which is composed of a conductive vanadate glass obtained by the process.
At least one discharge electrode for generating ions by applying high voltage to air to ionize;
A power supply for supplying power to the discharge electrode;
In an ionizer having
An ionizer, wherein the discharge electrode is the discharge electrode according to claim 1.