JP2011088059A - Dust collector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem of conventional methods of manufacturing a coating material by compounding a resin curing agent after a conductive material is dispersed to a base resin, wherein, on forming a semiconductivity coating film of an electrode plate used for a dust collector, the base resin penetrates between particles of a conductive material to ruin the electric conductivity efficiency. <P>SOLUTION: A second process for dispersing the conductive material to a mixed liquid obtained by a first process is provided after the first process for mixing the base resin with the resin curing agent. The contact of the particles of the conductive material is moderately secured by applying the mixed liquid obtained by the second process to the base material of the electrode plate as the coating material, and a conductivity is efficiently drawn out. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing an electrode plate for use in an electric dust collector that removes particulate suspended matter in the air in the field of air purification.

  Particulate suspended matter in the air, that is, dust, has been known as a cause of illnesses such as asthma and has been a target for removal in the past, but in recent studies, the particle size is 2.5 micrometers or less. There is a report that dust (so-called PM2.5) may induce diseases such as lung cancer, and further improvement of the collection technology is required. Among them, the dust collector using electric dust collection technology is superior in collecting dust with a small particle size with a particle size of micrometer or less, and the pressure loss is lower than the conventional filter system, and the blower There is an advantage that the burden on is small.

  Conventionally, as this type of dust collector, a charged part that charges dust by discharge is provided in the previous stage, and electrode plates are stacked in the subsequent stage, and different electric voltages are applied alternately to form an electric field to charge the charged dust. What provided the dust collection part which collects is known. Under the high voltage required for ensuring dust collection efficiency, spark discharge may occur between the electrode plates of the dust collection section, and it is necessary to consider the design to avoid this. As a method for preventing this spark discharge, there is a method of using a semiconductive material for the electrode plate.

  Conventionally, as an example of this method, there is one using a mixture of a base resin, a conductive material, and a curing agent as a semiconductive material (see, for example, Patent Document 1).

  That is, it can be assumed that a semiconductive electrode is formed by applying a semiconductive mixed material in a thin film as a paint on the surface of a resin substrate, etc., which is a base material of an electrode plate, and the coating film is cured. is there.

  An electrode plate having such a semiconductive material as a paint and a semiconductive coating film formed on a base material will be described with reference to FIG. As shown in FIG. 6, the electrode plate 101 includes a base material 102 and a semiconductive coating film 103, and the semiconductive coating film 103 includes a base resin 104 and a conductive material 105. The conductive effect of the semiconductive coating film 103 is established by the continuous contact between the particles of the conductive material 105 and the particles. However, since the particles of the conductive material 105 are dispersed in the base resin 104, the particles are It is not necessarily in contact, and it is considered that there are many that are adjacent to each other with the base resin 104 interposed therebetween. Since the conductivity of the semiconductive coating film 103 is determined by the abundance ratio of the conductive material 105 in the base resin 104 and the closeness between the particles of the conductive material 105, the conductivity of the electrode plate 101 constituting the dust collector is determined. Even when a high voltage is applied between the electrode plates, appropriate electrical conductivity is generated so that no spark discharge occurs, that is, appropriate electrical surface resistivity is expressed on the surface of the semiconductive coating film 103. Thus, it is only necessary to design the paint and the coating film.

JP-A-5-88510

  The general procedure for mixing the paint is to mix and disperse the conductive material in the base resin, which is the main body of the paint, and finally blend the resin curing agent. After adding the resin curing agent, the base resin and the resin curing agent are combined to form a polymer and form a strong coating film. In the case of such a general procedure, the resin curing agent is added. Before, when the conductive material particles are dispersed in the base resin, the electrically conductive base material intervenes between adjacent particles of the conductive material, so that the conductive material There is a problem in that electrical resistance is generated between the particles, and the conductivity of the resulting coating film cannot be drawn out efficiently and high.

  The present invention solves such a conventional problem, and by ensuring the contact between the particles of the conductive material, it is a semiconductive material that efficiently extracts high conductivity from the blended amount of the conductive material. It aims at providing the manufacturing method of an electrode plate with a coating film.

  In order to achieve the above object, the method for producing a semiconductive electrode plate according to the present invention has a conductive material added to the mixed liquid obtained in the first step after the first step of mixing the base resin and the resin curing agent. And the mixture obtained in the second step is applied as a paint to a flat plate.

  According to the method for producing a semiconductive electrode plate of the present invention, an effect that a high conductivity can be efficiently extracted from a blended amount of a conductive material can be obtained.

Flow chart of Embodiment 1 of the present invention The graph showing the relationship between the leaving time of the liquid mixture in Embodiment 2 of this invention, and the surface resistivity of a coating film The graph showing the relationship between the standing time before coating film drying and the surface resistivity of the coating film in Embodiment 3 of the present invention The graph showing the relationship between the weight ratio of the electroconductive material with respect to the base resin weight in Embodiment 4 of this invention, and the surface resistivity of a coating film Conceptual diagram of a coating film prepared using paint mixed in a conventional process Conventional process flow diagram

  In the method for producing a semiconductive electrode plate according to claim 1 of the present invention, after the first step of mixing the base resin and the resin curing agent, the conductive material is added to the mixed liquid obtained in the first step. It has the 2nd process to disperse | distribute and it applies to the base material of an electrode plate as a coating material the liquid mixture obtained at a 2nd process. In order to form a semiconductive coating film so that the conductivity is stable on the electrode plate, the base resin is used so that the particulate conductive material is uniformly dispersed in the paint when preparing the semiconductive paint. Is a fluid liquid. Resin hardeners are blended to harden the paint film in order to make the paint film durable against impacts and chemicals. The coating is cured by molecularization.

  For coloring paints, etc., usually a particulate color pigment is mixed and dispersed in a base resin, and finally a paint containing a resin hardener is applied to the paint and the paint is applied to the fabric to cure the coating film. The conductive material in the semiconductive paint referred to in the present invention corresponds to the color pigment in the paint for coloring. Inside the coating film, the concentration of the particles of the conductive material and the degree of proximity between the particles determine the conductivity of the coating film, and no spark discharge occurs when a high voltage is applied between the electrode plates of the dust collector. The blending amount of the conductive material is set so as to have such an appropriate conductivity. However, the conventional method of mixing the resin curing agent as the second step in the mixed solution obtained in the first step after the first step of mixing and dispersing the conductive material in the base resin is as follows: In the first step, the electrically insulating base resin penetrates into the conductive material and intervenes between the particles, so that the electrical connection formed by the conductive material is weakened, and the conductivity inside the final coating film is reduced. The rate is lower than the value that can be achieved. That is, when it is attempted to exhibit as high conductivity as possible with a certain amount of conductive material that has been introduced, it is advantageous that the conductive material is not highly dispersed in the base resin.

  In the method of the present invention, the base resin and the resin curing agent are mixed as the first step, and thereby the base resin and the resin curing agent are combined and polymerized. In the middle of the polymerization, by adding a conductive material as the second step, the polymerized part of the base resin is less likely to intervene between the particles of the conductive material, making it conductive. It is considered that the contact between the particles of the material is appropriately ensured, and the conductivity of the coating film when the coating film is cured is higher than that produced by the conventional method. However, when the bonding between the base resin and the resin curing agent proceeds, the dispersibility of the particles of the conductive material deteriorates and the conductivity of the coating film cannot be sufficiently obtained. The target interval should be short.

  The mixed liquid obtained after finishing the second step becomes a semiconductive paint to be applied to the base material of the electrode plate. For example, there is a screen printing method, and if this method is used, a stable thin film is formed. Is possible. In order to promote the bonding between the base resin and the resin curing agent in the coated film after coating, the coating film is heated for a certain time to be cured. When the coating film is allowed to stand at room temperature for a certain period of time after coating, the stable conductivity can be obtained. The longer the standing time, the higher the conductivity of the final coating film.

  According to a fourth aspect of the present invention, there is provided a dust collecting apparatus in which the semiconductive electrode plates according to any one of the first to fourth aspects are stacked at regular intervals, and different voltages are applied alternately for each stack. It is characterized by providing a part. By laminating a semiconductive electrode plate having a moderate conductivity, that is, a surface resistivity of 10 7 to the 12th power / Ω order, and applying different voltages alternately for each lamination, It is possible to construct a dust collecting portion that does not cause spark discharge while forming an electric field. By introducing the dust charged by the upstream charging unit into the downstream dust collecting unit, the dust can be collected. The surface resistivity is an electric resistance value obtained from a current flowing when a constant voltage is applied in the surface direction. If the surface resistivity is 10 7 Ω / □ or less, the probability of occurrence of a spark discharge is significantly increased. If the surface resistivity is 10 13 Ω / □ or more, the surface potential is increased when a voltage is applied to the surface. It is known that it takes a very long time to obtain 3 minutes or more. To eliminate the spark discharge and obtain high dust collection performance by setting the surface resistivity to 10 7 to 12th power / square. It is possible to form an electric field.

  In addition, the conductive material is a metal oxide. A conductive material containing a commonly used water-absorbing polymer is susceptible to fluctuations in electrical conductivity due to the influence of humidity in the air. Therefore, even if a semiconductive coating film is formed using a water-absorbing polymer, the conductivity of the electrode plate surface is not stable. On the other hand, metal oxides are less susceptible to humidity, and by using conductive metal oxides such as zinc oxide and potassium titanate as semiconductive materials, an electrode plate having a stable semiconductive coating film can be obtained. can get.

  Further, the metal oxide is tin oxide or tin oxide doped with antimony. Tin oxide has a small change in resistance value due to the applied voltage. This is because the conductive mechanism of tin oxide is due to oxygen defects in the crystal lattice. Further, tin oxide has a property that it is difficult to dissolve in acid or alkali. Therefore, it is possible to obtain a chemically and electrically stable semiconductive coating film by using tin oxide as a semiconductive material. Further, by doping tin oxide with antimony, an N-type semiconductor structure can be obtained. Therefore, the conductivity is improved as compared with the case where no antimony is doped, and the semiconductivity can be obtained with a smaller amount.

  Further, the semiconductive material is characterized in that tin oxide doped with tin oxide or antimony is attached to carrier particles having a larger particle diameter. In order for the semiconductive coating film obtained from tin oxide to have semiconductivity, it is necessary for the tin oxide particles to contact each other in the semiconductive coating film. In order to realize this, a large amount of expensive tin oxide particles is required, which requires high costs. If the tin oxides are in contact, equivalent semiconductivity can be obtained. Therefore, semi-conductivity can be obtained with a small amount of tin oxide by attaching tin oxide, which is a smaller particle, to the surface of large support particles made of chemically stable materials such as titanium oxide. It becomes.

  Further, when a resin such as a thermoplastic polyester resin, a vinyl chloride resin, or a polyol resin is used as the base resin, a resin having a high solubility in a solvent, that is, a relatively low molecular weight is used in order to form a coating material. Low molecular weight resins are easy to dissolve in oil and surfactant. For example, when oil particles and surfactant particles in the air are collected, the oil particles and surfactant particles adhering to the surface are not contained in the semiconductive coating film. Dissolves the resin, resulting in degradation of the semiconductive coating. Here, by using polyisocyanate or the like as a resin curing agent, the OH group in the base resin is cross-linked, and the resin is polymerized. Therefore, it is possible to obtain a chemically stable semiconductive coating film in which the base resin does not dissolve in oil or surfactant.

(Embodiment 1)
A semiconductive paint was prepared by selecting an acrylic polyol resin as a base resin, a polyisocyanate resin as a resin curing agent, and a tin oxide carrier doped with antimony as a conductive material, and a titanium oxide carrier. FIG. 1 is a flowchart for preparing a paint. First, the base resin and the resin curing agent are mixed at a weight ratio of 7: 3 to obtain a mixed solution. This mixing step is called the first step. Next, the mixed liquid obtained in the first step was mixed with twice the amount of the conductive material, and this was used as the second step. The liquid mixture obtained here was used as a semiconductive paint, and applied to a flat plate of PET resin which is a base material of the electrode plate by a screen printing method. After printing, the coating film was allowed to stand at room temperature for 30 minutes and heated at 100 ° C. for 20 minutes to cure the coating film. As described in Embodiment 3, the longer the time to stand at room temperature, the better. This coating film is designated as sample A.

  As a sample for comparison, a sample prepared by mixing paint in the conventional process was also prepared. FIG. 6 is a flow chart of the process and is as follows. The base resin and the conductive material are mixed and this is used as the first step, and the resin curing agent is mixed with the mixed solution obtained in the first step, and this is used as the second step. Each material was the same as in sample A, and the same amount was blended. The paint obtained here was applied to a PET resin plate in the same manner as in Sample A, and the coating film was cured. This is designated as sample B.

  About sample A and B, the electroconductivity of each coating film was evaluated by measuring the surface resistivity of the coating-film surface. As a result, the surface resistivity of sample A is 2.4 × 10 7 Ω / □, and sample B is 1.3 × 10 9 Ω / □. The resistivity decreased about 50 times, that is, the conductivity increased about 50 times.

(Embodiment 2)
In the same manner as in the first embodiment, an acrylic polyol resin as a base resin, a polyisocyanate resin as a resin curing agent, a tin oxide doped with antimony as a conductive material, supported on a titanium oxide carrier, a base resin and a resin The curing agent was mixed at a weight ratio of 7: 3 and this was the first step.

  Next, as the second step, a certain amount of the conductive material is mixed with the mixed liquid obtained in the first step. Here, the mixed liquid is allowed to stand for a certain period of time before the conductive material is mixed. . By allowing it to stand, bonding between the base resin and the resin curing agent proceeds, and thus it was confirmed whether or not the conductivity of the finally obtained coating film, that is, the surface resistivity changed. Several points were allowed to stand between 10 minutes and 24 hours. When the set standing time had elapsed, a conductive material was mixed with the mixed solution to obtain a semiconductive coating material, which was applied to a flat plate of PET resin by a screen printing method. After printing, the coating film was allowed to stand at room temperature for 30 minutes and heated at 100 ° C. for 20 minutes to cure the coating film.

  FIG. 3 is a graph showing the relationship between the standing time of the mixed liquid between the first step and the second step and the surface resistivity of the coating film. From this graph, it can be said that the longer the standing time between the first step and the second step, the higher the surface resistivity of the coating film. Therefore, in order to obtain a coating film having higher conductivity with less conductive material, it is better that the standing time between the first step and the second step is short.

(Embodiment 3)
A semiconductive paint was prepared by selecting an acrylic polyol resin as a base resin, a polyisocyanate resin as a resin curing agent, and a tin oxide carrier doped with antimony as a conductive material, and a titanium oxide carrier. First, the base resin and the resin curing agent were mixed at a weight ratio of 7: 3, and this was used as the first step. Next, a certain amount of conductive material was mixed with the liquid mixture obtained in the first step, and this was used as the second step. The liquid mixture obtained here was used as a semiconductive paint, and applied to a flat plate of PET resin which is a base material of the electrode plate by a screen printing method. After printing, the coating film was allowed to stand at room temperature for a certain time and heated at 100 ° C. for 20 minutes to cure the coating film. It was confirmed how the surface resistivity of the obtained coating film changes when the time for which the coating film is allowed to stand at room temperature is changed from printing to drying.

  FIG. 4 is a graph showing the relationship between the standing time before drying the coating film and the surface resistivity of the coating film. From the graph, it can be said that the surface resistivity of the coating film tends to be lower as the time for which it is left is longer.

(Embodiment 4)
A semiconductive paint was prepared by selecting an acrylic polyol resin as a base resin, a polyisocyanate resin as a resin curing agent, and a tin oxide carrier doped with antimony as a conductive material, and a titanium oxide carrier. First, the base resin and the resin curing agent were mixed at a weight ratio of 7: 3, and this was used as the first step. Next, the conductive material was mixed with the liquid mixture obtained in the first step, and this was used as the second step. Regarding the weight to mix the conductive material, prepare four levels of 1.50, 1.67, 2.00, 2.33, 2.83 times the blending amount of the base resin. A semiconductive paint was prepared. About each coating material, the semiconductive coating film was formed and the surface resistivity was measured.

  FIG. 5 is a graph showing the surface resistivity of the coating film as a logarithmic value with respect to the ratio of the blending weight of the conductive material to the weight of the base resin in the semiconductive paint. The surface resistivity of the coating film tends to increase rapidly as the blending ratio of the conductive material decreases, but the surface resistivity is suitable for a semiconductive electrode plate for constituting the dust collection part of the dust collector. In order to obtain a coating film having 10 7 to 12th power Ω / □, the ratio is 1.50 to 2.18.

  The electrode plate and the dust collector according to the present invention are required to have high dust collection performance and safety because they can obtain high dust collection performance even when oil adheres and at the same time avoid spark discharge of the dust collection section. It is useful as a dust collecting device mounted on a dust collector to be used, for example, an oil mist dust collector in a factory, a domestic air cleaner, or an air supply type ventilation fan.

101 Electrode plate 102 Base material 103 Semiconductive coating 104 Base resin 105 Conductive material

Claims (10)

After the first step of mixing the base resin and the resin curing agent, the second step of dispersing the conductive material in the mixed liquid obtained in the first step has a mixed liquid obtained in the second step. A method for producing a semiconductive electrode plate, wherein the electrode plate is applied as a semiconductive paint. The method for producing a semiconductive electrode plate according to claim 1, wherein after the first step, the second step is performed after a maximum of 20 minutes. 2. The method for producing a semiconductive electrode plate according to claim 1, wherein the coating film is allowed to stand at room temperature for a certain period of time before the coating film of the semiconductive paint applied to the electrode plate is heated and dried. A dust collecting portion and a charging portion are provided, and the dust collecting portion and the charging portion have a semiconductive electrode plate manufactured using the method for manufacturing a semiconductive electrode plate according to claim 1, and the semiconductive An electrode plate has a surface resistivity of 10 7 to 10 12 Ω / □. 5. The dust collector according to claim 4, wherein the conductive material is a metal oxide having conductivity. 6. The dust collector according to claim 5, wherein the metal oxide is tin oxide or tin oxide doped with antimony. 7. The dust collector according to claim 4, wherein the conductive material is tin oxide or tin oxide doped with antimony added to carrier particles having a larger particle diameter. 8. The dust collector according to claim 4, wherein the base resin is a polyol. 9. The dust collector according to claim 4, wherein the resin curing agent is polyisocyanate. The dust collector according to claim 9, wherein the weight ratio of the metal oxide to the weight of the base resin in the mixed paint is 1.50 to 2.18.

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