JP2018051466A - Coated electric insulator manufacturing method, and electric insulator coating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a coated electric insulator and an electric insulator coating device which can supply a liquid drop group of a coating material stably to an electric insulator.SOLUTION: A manufacturing method for a coated electric insulator comprises: the step of forming a water droplet group or a water film on the surface of an electric insulator EI; and a step of feeding the liquid droplet group of a charged coating material on the surface of the electric insulator EI.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method of manufacturing a coated electrical insulator and an electrical insulator coating apparatus.

  Conventionally, a spraying method is known in which droplets of a coating material charged to a positive or negative potential are formed and moved toward an electrode having a negative or positive potential. According to this, the coating material can be efficiently coated on the object arranged on the electrode. In particular, it is possible to form a thin coating layer while suppressing waste of the coating material.

JP 2006-058628 A JP 2004-136655 A

  By the way, when the object to be coated is an electrical insulator, the droplet group of the coating material cannot be stably supplied to the object, and coating may be difficult. This is partly because the object is charged to the same potential as the droplet group by supplying the droplet group of the coating material, and an electrostatic repulsive force is generated between the droplet group supplied thereafter.

  The present invention has been made in view of the above problems, and can provide a method for manufacturing a coated electrical insulator and an electrical insulator coating apparatus capable of stably supplying a droplet group of a coating material to the electrical insulator. The purpose is to provide.

  As a result of intensive studies, the present inventors can stably supply a droplet group of a coating material even if an electrical insulator is formed by previously forming a water droplet group or a water film on the surface of the electrical insulator. I found out. As one of the reasons, it is conceivable that the conductivity of the surface of the electrical insulator is improved by the water droplet group or the water film, and charging is suppressed.

The method for producing a coated electrical insulator according to the present invention includes a step of forming a water droplet group or a water film on the surface of the electrical insulator,
Supplying a droplet group of a charged coating material to the surface of the electrical insulator.

  According to the present invention, the droplet group of the coating material can be sufficiently supplied to the electrical insulator.

  Here, the step of forming a water droplet group or a water film on the surface of the electrical insulator may include exposing the electrical insulator having a surface temperature A to a gas having a dew point B equal to or higher than the surface temperature A. it can.

  According to this, moisture in the gas is condensed on the surface of the electrical insulator. The amount of water condensation is preferable because it can be easily controlled based on the temperature difference between the surface temperature A and the dew point. Moreover, moisture can be uniformly supplied to the surface.

  Further, B−A ≧ 2 ° C. may be satisfied.

  Further, the dew point of the gas in the space where the electrical insulator exists can be maintained within B ± 15 ° C. until the droplet group of the coating material is supplied after the water droplet group or the water film is formed. it can. According to this, it is excellent in controllability of water content.

  The electrical insulator may be any selected from the group consisting of food, pharmaceuticals, semiconductors, ceramics, resins, and combinations thereof.

  The coating material may include a film forming material and a liquid component.

The electrical insulator coating apparatus according to the present invention includes a pretreatment unit that forms a water droplet group or a water film on the surface of the electrical insulator,
A coating material spraying section for supplying droplets of the charged coating material to the surface of the electrical insulator;

  Here, the pretreatment unit can expose the electrical insulator having the surface temperature A to a gas having a dew point equal to or higher than the surface temperature A.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the coated electrical insulator which can supply stably the droplet group of coating material with respect to an electrical insulator and the coating apparatus of an electrical insulator are provided.

1 is a schematic view of an electrical insulator coating apparatus 1000. FIG. 1 is a schematic view showing an example of an electrostatic sprayer 100. FIG.

  Preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view of an electrical insulator coating apparatus 1000.

  The coating apparatus 1000 mainly includes a belt conveyor 200, a cooling unit 300, a dew condensation unit (pre-processing unit) 400, a coating material spraying unit 500, and a drying unit 600.

  The belt conveyor 200 is a moving means having a belt 200a, and moves the electrical insulator EI placed on the belt 200a in the order of the cooling unit 300, the dew condensation unit 400, the coating material spraying unit 500, and the drying unit 600.

  The cooling unit 300 includes a chamber 310 and a cooling mechanism 320 that lowers the temperature of the gas (for example, air) in the chamber 310, and cools the surface temperature of the electrical insulator EI in the cooling unit 300 to the surface temperature A. To do. The surface temperature A can be set to, for example, -20 to 20 ° C. The surface temperature A of the electrical insulator EI can be measured by a temperature sensor such as an infrared radiation thermometer, and the degree of cooling by the cooling mechanism 320 can be controlled.

  The dew condensation unit 400 includes a chamber 410 and a dew point adjustment unit 420 that adjusts the dew point of the gas (for example, air) in the chamber 410. The dew point adjustment unit 420 controls the dew point B of the gas in the chamber 410 to be equal to or higher than the above surface temperature A. Specifically, 0 ≦ B−A <2 ° C., B−A ≧ 2 ° C., B−A ≧ 3 ° C., B−A ≧ 4 ° C., B−A ≧ 5 ° C., B−A ≧ 6 ° C., B The dew point B can be controlled so that −A ≧ 7 ° C., B−A ≧ 8 ° C., B−A ≧ 9 ° C., B−A ≧ 10 ° C., B−A ≧ 11 ° C. From the viewpoint of making the amount of water adhering to the surface of the electrical insulator EI an appropriate amount, B−A ≦ 20 ° C. can be satisfied. The dew point adjustment unit 420 can control the dew point of the gas by controlling the humidity in the chamber 410 by a known method, for example, a combination of a dew point meter or a temperature / humidity meter and a humidifying / dehumidifying mechanism.

  The residence time of the electrical insulator EI in the dew condensation part 400 can be 5 to 600 seconds.

  Within the range satisfying the dew point B, for example, the temperature in the chamber 410 can be 15 to 40 ° C.

  The coating material spraying unit 500 includes a chamber 510 and an electrostatic sprayer 100. The electrostatic sprayer 100 supplies a droplet group of the charged coating material to the electric insulator EI on the belt 200a. The diameter of the droplet group can be set to 0.5 to 100 μm, for example.

  The coating material is not particularly limited as long as it is liquid. For example, the coating material can include a film-forming material and a liquid component that dissolves or disperses the film-forming material. When the film-forming material is melted and can be sprayed as it is, no liquid component is required.

  The film-forming material is a component that forms a film by evaporating a liquid component from the coating material and remaining without evaporating. Examples of the film forming material are resin, and / or inorganic particles, and polysaccharides.

  Examples of the resin are natural resins such as shellac and beeswax.

  Other examples of the resin are synthetic resins such as epoxy resin (for example, bisphenol A type epoxy resin, novolac type epoxy resin), polyhydroxystyrene resin, acrylic resin, urethane resin, silicone resin, polyamideimide resin, polyimide resin, and the like. is there.

  The resin may be thermoplastic or curable. The curable resin can contain a monomer and / or a prepolymer and a curing agent. The curing agent can be arbitrarily selected depending on the monomer, prepolymer, curing conditions after electrostatic coating (photocuring, thermal curing, reaction curing, etc.) and the like. The curable resin can also include a polymerizable monomer and / or a polymerizable prepolymer.

  The resin can include a photosensitizer such as naphthoquinonediazide, in which case the resin can be a photosensitive resist.

  The resin can contain various additives such as a surfactant and a leveling material.

  Specifically, the resin as described above can be a brightener, a photosensitive resist, an adhesive, a coating agent, or the like.

  Examples of inorganic particles are metal particles and oxide particles. Examples of metal particles are silver particles, gold particles, copper particles, and the like. Examples of the oxide particles include ceramic particles such as titania, silica, and alumina, and glass particles.

  The example of the particle size of a metal particle or an oxide particle is 0.001-100 micrometers.

  The liquid component can dissolve or disperse the film-forming component. Examples of liquid components are γ-butyrolactone, ethyl lactate, acetone, diglyme, cyclopentanone, ethanol and other alcohols, and water. The liquid component can be a mixture of these compounds.

  The liquid component is preferably a liquid at 20 to 30 ° C. Further, the boiling point of the liquid component can be 70 ° C. or higher, and can be lower than 260 ° C. When the boiling point is 70 ° C. or higher, a liquid film is easily formed on the object. Further, when the boiling point is less than 260 ° C., the drying time can be shortened and the productivity is easily improved.

  The coating material can include additives. Examples of additives are surfactants, leveling agents and the like. The concentration of the additive can be 10% by mass or less.

  The method for preparing the coating material is not particularly limited. For example, the film forming component and the liquid component may be mixed.

  An example of the electrostatic sprayer 100 is shown in FIG. The electrostatic sprayer 100 includes a nozzle 1, a counter electrode 20, a power supply 30, and a coating material supply unit 40.

  The nozzle 1 is connected to a power source 30, and the nozzle 1 functions as a cylindrical electrode that charges the coating material sent from the coating material supply unit 40. The nozzle 1 is connected to the line L10 from the coating material supply unit 40 using the joint 4 at the upper end.

  At least a part of the inner surface of the nozzle 1 is formed of a conductive material such as stainless steel. All of the inner surface of the nozzle 1 can be formed of a conductive wall, or the entire nozzle 1 can be formed of a conductive material. Although the internal diameter of the nozzle 1 is not specifically limited, For example, it can be 10-1000 micrometers.

  The counter electrode 20 is disposed on an extension line of the axis of the nozzle 1 with the belt 200 a interposed therebetween, and is separated from the nozzle 1. The counter electrode 20 is preferably grounded. The distance between the nozzle 1 and the electrical insulator EI is not particularly limited, but can be, for example, about 10 to 60 mm.

  The power source 30 applies a voltage between the nozzle 1 and the counter electrode 20. Usually, the voltage is a direct current and can also be supplied in pulses. Although a voltage is not specifically limited, In this embodiment, it can be set to 5-20 kV. The voltage is preferably applied to the counter electrode 20 so that the nozzle 1 side is positive.

  The coating material supply unit 40 supplies the coating material to the nozzle 1 via the line L10. The coating material supply unit 40 includes a tank 41 that stores the coating material, and a pump 42 that supplies the coating material from the tank 41 to the nozzle 1 via the line L10. In this embodiment, the coating material is supplied to the nozzle 1 via the line L10 by supplying air to the tank 41 in which the pump 42 is in a sealed state.

  In such an electrostatic sprayer 100, when a coating material is supplied from the coating material supply unit 40 to the nozzle 1, the coating material is charged in the nozzle 1, and the charged coating material discharged from the tip of the nozzle 1 is split. Thus, a droplet group LD is formed. The charged droplet group LD flies toward the counter electrode 20 having a reverse potential. Accordingly, the charged droplet group LD is supplied to the electric insulator EI placed on the belt 200a, and the surface of the electric insulator EI is covered with the coating material. As a covering mode, a coating material film may be formed on the electrical insulator EI. When the coating amount is reduced, a droplet group of the coating material is formed on the surface of the electrical insulator EI. There is also a case.

  The thickness of the film can be, for example, 0.1 to 500 μm. The film can be made thicker by spraying the coating material multiple times.

  From the viewpoint of maintaining the amount of water condensed on the electrical insulator EI, the dew point in the coating material spray unit 500 is within ± 15 ° C., within ± 10 ° C., within ± 5 ° C., ± 4 ° C. It can be within ± 3 ° C, within ± 3 ° C, within ± 2 ° C, and within ± 1 ° C.

  The drying unit 600 includes a chamber 610 and a dryer 620, and dries the coating material supplied to the electrical insulator EI. Drying is the removal of the liquid component from the coating material on the electrical insulator EI. Examples of the drying method of the dryer 620 are hot air supply, infrared heating, microwave heating, and supply of dehumidified air.

  Then, the manufacturing method of the coated electrical insulator EI using the coating apparatus 1000 of this embodiment is demonstrated.

  First, an electrical insulator EI is prepared. The 1st example of the electrical insulator EI is a foodstuff and a pharmaceutical.

  Examples of food are chocolate, oil-based cream, butter, and food coated with one or more of the above foods. Examples of medicinal products are ointments and suppositories.

  Other examples of electrical insulators are semiconductors, glass, ceramics, resins and waxes. These can be used for electronic components, optical components, and the like.

  There is no limitation on the size of the electrical insulator EI. Further, the shape of the electrical insulator EI is not particularly limited, and can be applied to all shapes such as a rod shape and a plate shape.

  Next, the electric insulator EI is placed on the belt 200a of the belt conveyor 200, moved to the cooling unit 300, and the surface of the electric insulator EI is cooled to the surface temperature A.

Next, the electric insulator EI cooled to the surface temperature A is moved to the dew condensation part 400, and the electric insulator EI having the surface temperature A is exposed to a gas having a dew point B equal to or higher than the surface temperature A to thereby form the electric insulator. Water condenses on the EI. Thereby, a water droplet group or a water film is formed on the surface of the electrical insulator EI. The amount of water can be 0.1 to 6.0 mg / cm ² in terms of the weight per unit surface area of the electrical insulator EI.

  Next, the electric insulator EI in which condensation has occurred is moved to the coating material spraying unit 500, and a droplet group LD of charged coating material is supplied to the electric insulator EI. Thereby, a droplet group or a liquid film of the coating material is formed on the surface of the electrical insulator EI.

  Finally, the electric insulator EI is moved to the drying unit 600 to remove the liquid component from the coating material to form a solid film, and the coating process of the electric insulator EI is completed.

  According to this embodiment, since the water droplet group or the water film is formed on the electric insulator EI before the droplet group LD of the charged coating material is sprayed, the conductivity of the surface of the electric insulator EI is reduced. Get higher. Therefore, even if the charged droplet group LD of the coating material is supplied, it is difficult to accumulate charges, and the droplet group LD of the coating material can be stably supplied to the electrical insulator. Therefore, even an electrical insulator can be coated by supplying a droplet group of a charged coating material. With such a method, uniform coating without unevenness is possible, and there is little waste of the coating material.

  Furthermore, according to the present embodiment, a water droplet group or a water film is formed on the surface of the electrical insulator EI by condensation, so that the water droplet group or water film can be uniformly applied to the surface of the electrical insulator EI. The water supply amount can be easily adjusted. Therefore, uneven coating is less likely to occur.

  Further, since water is generated by condensation, it can be easily applied to foods, pharmaceuticals, and the like.

  Moreover, since the dew points of the dew condensation part 400 and the coating material spray part are controlled, it is easy to control the amount of water droplets or the amount of water film attached.

  In addition, when the electrical insulator EI is chocolate or a food coated with chocolate, the electrical insulator EI itself is usually cooled in the process of manufacturing (solidifying process) and storage. Therefore, the condensation process can be performed on the cooled chocolate, and the process can be simplified.

  The present invention is not limited to the above embodiment, and various modifications can be made.

  For example, the forms of the cooling part 300, the dew condensation part 400, the coating material spraying part 500, and the drying part 600 may not be the above forms.

  For example, in the electrostatic sprayer 100 of the coating material spraying unit 500, a non-conductive nozzle may be used and an electrode may be inserted into the nozzle, or an electrode may be placed outside the spray nozzle to charge the droplet group. You may let them. In any case, it is only necessary to supply a charged droplet group to the electrical insulator.

  Moreover, in the coating material supply part 40 of the coating material spraying part 500, a supply mechanism is not specifically limited to said form, Various mechanisms can be utilized.

  Further, depending on the environmental conditions, it can be implemented without each chamber. For example, if the surface temperature of the electrical insulator EI is cooled to a temperature equal to or lower than the dew point B of the surrounding atmosphere in the cooling unit 300, dew condensation is possible only by exposing the electrical insulator EI to the surrounding atmosphere. No dew point adjustment at 400 is required. Further, the present invention can be implemented without positively adjusting the dew point in the coating material spraying unit 500.

  Further, the dew condensation part 400 and the coating material spray part 500 may be provided in one chamber.

  Moreover, in the movement of the electrical insulator EI between each part, means other than the belt conveyor may be used, or may be performed manually.

  Furthermore, in the said embodiment, although the electrical insulator EI cooled by the cooling unit 300 is condensed by the dew condensation unit 400, a water droplet group or a water film is formed on the electrical insulator EI. Even if water droplets or a water film is applied to the electrical insulator EI by spraying water on the insulator EI, immersing the electrical insulator EI in water, or brushing the electrical insulator EI with water. is there.

  Moreover, in the said embodiment, although the atmosphere of the dew condensation part 400 and the coating material spray part 500 is air | atmosphere, if it is a gas containing water vapor | steam, it will not specifically limit, For example, it can also be nitrogen atmosphere, argon atmosphere, etc. . Of course, the atmosphere of the cooling unit 300 and the drying unit 600 is not particularly limited.

  Further, when drying is possible by natural drying, the drying unit 600 is also unnecessary.

Example 1
38 mm × 20 mm × 7 mm plate-shaped white chocolate was prepared. As a coating material, an ethanol solution of shellac was prepared.

  The surface temperature of white chocolate was set to 14 ° C. in a thermostatic chamber. Next, the white chocolate was exposed to air having a dew point of 17 ° C. (temperature 22 ° C., humidity 75%) for 60 seconds. Thereafter, charged droplet groups of an ethanol solution of shellac were supplied onto the upper surface of the white chocolate with an electrostatic spraying device manufactured by Nagase Techno Engineering. The temperature and dew point of the air in the atomizer were the same as the exposure air. The nozzle diameter was 500 μm, the liquid feed pressure was 4.8 kPa, and the voltage was 9.1 kV. The conveyor speed at the time of application was 20 mm / s.

(Example 2)
It was the same as Example 1 except that the surface temperature of the chocolate was 6 ° C. in a thermostatic chamber.

(Comparative Example 1)
It was the same as Example 1 except that the surface temperature of the chocolate was 21 ° C. in the thermostat.

(Comparative Example 2)
It was the same as Example 1 except that the surface temperature of the chocolate was 21 ° C. and the dew point of the exposure air was 9 ° C. (air temperature 21 ° C., humidity 46%) in the thermostat.

(Comparative Example 3)
It was the same as Example 1 except that the surface temperature of the chocolate was 13 ° C. and the dew point of the exposure air was 10 ° C. (air temperature 21 ° C., humidity 48%) in the thermostat.

(Evaluation)
Based on the change in weight of the chocolate, the amount of shellac applied per unit area of the chocolate surface (upper surface) was calculated. The conditions and results are shown in Table 1.

  In Examples 1 and 2 in which (atmospheric dew point B-chocolate surface temperature A) is positive and condensation occurs on the surface, a sufficient amount of shellac could be applied, but B-A is negative and no condensation occurs Then, the shellac could not be applied sufficiently.

  Moreover, when visually observed, in Examples 1 and 2, no shellac unevenness was found.

  EI ... electric insulator, LD ... droplet group of coating material, 100 ... electrostatic sprayer, 400 ... condensation part (pretreatment part), 500 ... coating material spray part, 1000 ... coating apparatus for electrical insulator.

Claims (8)

Forming a droplet group or a water film on the surface of the electrical insulator;
Supplying a droplet group of a charged coating material to the surface of the electrical insulator. A method for producing a coated electrical insulator.   The method of forming a water droplet group or a water film on a surface of the electrical insulator includes exposing the electrical insulator having a surface temperature A to a gas having a dew point B equal to or higher than the surface temperature A. The method described.   The method according to claim 2, wherein B−A ≧ 2 ° C.   The dew point of the gas in the space where the electrical insulator exists is maintained within B ± 15 ° C. until the droplet group of the coating material is supplied after the formation of the droplet group or water film. Or the method of 3.   The method according to claim 1, wherein the electrical insulator is any one selected from the group consisting of foods, pharmaceuticals, semiconductors, ceramics, resins, and combinations thereof.   The method according to claim 1, wherein the coating material includes a film forming material and a liquid component. A pretreatment unit that forms a group of water drops or a water film on the surface of the electrical insulator;
A coating apparatus for an electrical insulator, comprising: a coating material spraying unit that supplies a droplet group of a charged coating material to a surface of the electrical insulator.   8. The electrical insulator coating apparatus according to claim 7, wherein the pretreatment unit exposes the electrical insulator having a surface temperature A to a gas having a dew point equal to or higher than the surface temperature A.

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