WO2013081029A1 - 静電塗装方法 - Google Patents
静電塗装方法 Download PDFInfo
- Publication number
- WO2013081029A1 WO2013081029A1 PCT/JP2012/080821 JP2012080821W WO2013081029A1 WO 2013081029 A1 WO2013081029 A1 WO 2013081029A1 JP 2012080821 W JP2012080821 W JP 2012080821W WO 2013081029 A1 WO2013081029 A1 WO 2013081029A1
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- coating
- paint
- coated
- conductive
- electrostatic
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
- B05D3/002—Pretreatement
- B05D3/005—Pretreatment for allowing a non-conductive substrate to be electrostatically coated
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D1/00—Processes for applying liquids or other fluent materials
- B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
- B05D1/04—Processes for applying liquids or other fluent materials performed by spraying involving the use of an electrostatic field
- B05D1/045—Processes for applying liquids or other fluent materials performed by spraying involving the use of an electrostatic field on non-conductive substrates
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
- B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
- B05B5/03—Discharge apparatus, e.g. electrostatic spray guns characterised by the use of gas, e.g. electrostatically assisted pneumatic spraying
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
- B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
- B05B5/053—Arrangements for supplying power, e.g. charging power
- B05B5/0533—Electrodes specially adapted therefor; Arrangements of electrodes
- B05B5/0535—Electrodes specially adapted therefor; Arrangements of electrodes at least two electrodes having different potentials being held on the discharge apparatus, one of them being a charging electrode of the corona type located in the spray or close to it, and another being of the non-corona type located outside of the path for the material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
- B05D7/50—Multilayers
- B05D7/52—Two layers
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P60/00—Technologies relating to agriculture, livestock or agroalimentary industries
- Y02P60/20—Reduction of greenhouse gas [GHG] emissions in agriculture, e.g. CO2
- Y02P60/21—Dinitrogen oxide [N2O], e.g. using aquaponics, hydroponics or efficiency measures
Definitions
- the present invention relates to an electrostatic coating method.
- electrostatic coating means that an object to be coated is an earth electrode, an electrode on the coating device side is a cathode, and an electrostatic field (electric lines of force) is formed by applying a high voltage therebetween, and paint particles are
- an electrostatic field electric lines of force
- This is a coating method in which a negative charge is applied and a paint is efficiently applied to an object by electrostatic force.
- Electrostatic coating improves coating efficiency (shortens the coating time by improving the paint throwing power) and improves coating efficiency (improves the amount ratio of paint applied to the object to be used) Effects).
- the object to be electrostatically coated is an electrode, it is necessary to have conductivity, and the following technique is used when performing electrostatic coating on a non-conductive object to be coated.
- ⁇ Providing temporary weak conductivity to the surface to be coated by antistatic treatment such as application of surfactant.
- ⁇ Give weak conductivity to the coated surface by grounding the coated surface and using conductive paint. -Increase in capacitance (potential drop with respect to charge amount) by applying or approaching a conductive substance on the back side of an object.
- the surface to be coated is applied by applying a conductive film such as a conductive primer.
- Conductivity is most common.
- a conductive film coating step is required as a pre-process of electrostatic coating, which increases man-hours and costs.
- the surfactant In the case of imparting weak conductivity by antistatic treatment such as application of a surfactant, the surfactant must be applied evenly and uniformly on the surface to be coated.
- the antistatic effect is obtained by the expression of a water molecule film formed by adsorbing moisture in the air on the surfactant film on the surface to be coated, a constant relative humidity control generally exceeding 60% is achieved. If it is necessary and the humidity control is insufficient, the coating efficiency fluctuates and the coating unevenness occurs, resulting in a decrease in coating quality.
- a surfactant application step is required as a pre-process of electrostatic coating, which increases man-hours and costs. In particular, for an object to be coated having a complicated shape such as a radiator grill of an automobile, appropriate equipment and management are required, and the cost is significantly increased.
- the conductive paint is spread from the vicinity of the grounding portion of the surface to be coated, so the increase in man-hours and cost is suppressed. Is done.
- the energized state of the grounding portion for example, the metal portion of the jig holding the object to be coated
- the contact state between the grounding portion and the object to be coated must be continuously maintained. For this reason, detailed maintenance such as frequent removal of dirt on the grounding portion is necessary, and the work is complicated.
- the present invention has been made in view of the above circumstances, and it is possible to continuously perform good electrostatic coating while suppressing an increase in man-hours and an increase in cost without incurring complicated operations. To provide a simple electrostatic coating method.
- the electrostatic coating method according to the first aspect of the present invention is a first coating step in which a first paint having conductivity is applied to a surface to be coated to form a first coating film. And before the first coating film is dried, the second coating film, which is negatively charged, is applied to the surface of the first coating film in a state in which free ions are suppressed to form a second coating film. 2 painting processes.
- the 1st painting process should just apply the 1st paint which has electroconductivity to a coated surface, and the coating method is arbitrary.
- the second paint is negatively charged by corona discharge from the discharge electrode, and free ions generated by the corona discharge are reduced or removed by a free ion removal electrode disposed in the vicinity of the discharge electrode. May be.
- a conductive paint is used as the second paint, and in the second painting process, a high voltage is directly applied from the high voltage electrode to negatively charge the conductive paint, thereby suppressing the generation of free ions. May be.
- the volume specific resistance value of the conductive paint is preferably 100 M ⁇ cm or less, and more preferably 20 M ⁇ cm or less.
- free ions are ions that are not used for charging the paint when the paint is negatively charged by corona discharge, and exist mainly as ionized air.
- the first coating film with weak conductivity is suppressed in a state where free ions are suppressed. Electrostatic coating is performed on the surface, and suppression of free ions reduces the amount of ions that reach the surface of the first coating film, and suppresses charging of the surface of the weakly conductive first coating film. For this reason, the surface charge of the weakly conductive first coating film can be maintained at a low level, and good electrostatic coating can be continuously performed.
- the method of reducing or removing free ions generated by corona discharge with a free ion removing electrode is advantageous in terms of a wide range of usable paints.
- the method of suppressing the generation of free ions by directly applying a high voltage to negatively charge the conductive paint does not require a corona discharge electrode and a free ion removal electrode, and there is a problem of paint contamination of the free ion removal electrode.
- the electrostatic coating gun used in the second coating process may include a paint supply path, a high voltage electrode, and a discharge port.
- a conductive paint circulates in the paint supply path.
- the high voltage electrode is provided in the paint supply path, and directly applies a high voltage to the conductive paint flowing through the paint supply path to charge the conductive paint negatively.
- the discharge port is provided at or near the tip of the paint supply path and discharges negatively charged conductive paint to the outside. That is, this electrostatic coating gun does not have a discharge electrode that performs corona discharge for negatively charging the conductive paint.
- the surface to be coated may have weak conductivity or insulation, and in the first coating step, the negatively charged first paint is applied to the surface to be coated while suppressing free ions. May be.
- the first paint can be applied in the same manner as the second paint, and a plurality of coating films can be easily applied.
- the first paint is negatively charged by corona discharge from the discharge electrode, and free ions generated by the corona discharge are placed near the discharge electrode. It may be reduced or removed by the arranged free ion removal electrode. Moreover, you may suppress generation
- the object to be coated is non-conductive (the surface to be coated is insulative)
- the imparting of weak conductivity to the coated surface may be performed by at least one of antistatic treatment of the coated surface, or grounding of the coated surface and the use of a conductive paint. You may carry out by carrying out the wipe application of the antistatic liquid to the to-be-coated surface.
- the third coating film is formed by applying the negatively charged third coating material to the surface of the second coating film in a state in which free ions are suppressed.
- a negatively charged fourth paint is applied to the surface of the third coating film while suppressing free ions.
- a desired number of coating films can be applied repeatedly by increasing the number of coating steps.
- a negatively charged paint is applied to an insulating coating surface in a state where free ions are suppressed.
- a coated surface having insulating properties is applied from the ground side. Even in the coating of a coated surface having such insulating properties, electrostatic coating of the coated surface is performed in a state where free ions are suppressed, and the suppression of free ions reduces the amount of ions reaching the coated surface. Suppresses charging of the coated surface. For this reason, the charging of the coated surface can be maintained at a low level, and electrostatic coating can be continuously performed.
- good electrostatic coating can be continuously performed while suppressing an increase in man-hours and an increase in cost without causing complication of work.
- FIG. 3 is an exploded perspective view of the electrostatic coating gun of FIG. 2. It is the photograph which image
- the electrostatic coating method of the present invention is to sequentially coat a plurality of paints on a surface to be coated having weak conductivity, and includes at least a first coating step and a second coating step.
- the first coating film is formed by applying the negatively charged first coating material to the surface to be coated while suppressing free ions.
- the second coating before the first coating is dried, the second coating, which is negatively charged, is applied to the surface of the first coating while suppressing free ions, and the second coating is applied. A film is formed. Since the surface of the first coating before drying has weak conductivity, the second coating can be electrostatically applied in the same manner as the first coating, and a plurality of coatings can be easily applied. be able to.
- the first coating process and the second coating process are both electrostatic coatings in which the paint is applied in a state where free ions are suppressed, the first coating process will be described as a representative of both.
- Examples of the spray gun used in the first painting process include the following two embodiments.
- a spray gun (electrostatic coating gun) 1 of this embodiment is an automatic spray gun, for example, and is used for electrostatic coating of a non-conductive object 20 to be coated.
- the spray gun 1 includes an insulating resin gun body 2, an insulating resin paint nozzle 3 attached to the tip of the gun body 2, and a front end portion of the gun body 2 to cover the outer periphery of the paint nozzle 3. And an insulating resin air cap (for example, a fan pattern spray type) 4.
- a cascade (high voltage generator) 5 in which a step-up transformer and a high-voltage rectifier circuit constituting a high-voltage generation circuit are integrally molded is housed in the upper part of the gun body 2.
- the connecting rod 6 having the property is disposed downward.
- the front end of the cascade 5 is in contact with the connecting rod 6 and both are electrically connected.
- a hole 10 is formed in the center of the paint nozzle 3, and an insulating resin electrode outer cylinder 7 is accommodated and supported in the hole 10.
- the rear end portion of the electrode outer cylinder 7 is inserted into a hole 11 formed in the gun body 2.
- a corona pin (for example, a tungsten discharge electrode) 8 is accommodated and supported at the center of the electrode outer cylinder 7.
- the front end of the hole 10 communicates with the outside through the discharge port 12, and the front end of the corona pin 8 passes through the discharge port 12 and protrudes from the front end of the electrode outer cylinder 7.
- the corona pin 8 is connected to the front end side of the protective resistor 14 built in the electrode outer cylinder 7.
- the rear end side of the protective resistor 14 is exposed from the rear end of the electrode outer cylinder 7 and is electrically connected to the connecting rod 6 via a spring 9 accommodated in the hole 10.
- the air cap 4 is provided with two types of air injection ports (not shown). One air injection port functions as atomizing air that atomizes the discharged paint, and the other injection port functions as pattern air that forms a fan-pattern spray.
- the high-frequency voltage taken in from the power connector (not shown) is supplied to the step-up transformer in the cascade 5 via a wiring cable (not shown) in the grip (not shown).
- the supplied high-frequency voltage is boosted by a step-up transformer, then further boosted by a high-voltage rectifier circuit and rectified at the same time, and a DC high voltage of minus several tens of thousands of volts is generated.
- the generated DC high voltage is applied from the cascade 5 to the corona pin 8 through the connecting rod 6, the protective resistor 14 and the spring 9, and corona discharge (stable air breakdown discharge that appears due to an unequal electric field concentrated on the tip of the pin). Generates a large amount of negative ions.
- a high voltage to be applied is preferably 60 kV or more.
- the gun body 2 has a paint circulation hole 16 communicating with the hole 11.
- the conductive paint is supplied from the paint circulation hole 16 to the hole 11, flows through the hole 10, and is discharged from the discharge port 12.
- a stainless steel free ion removal electrode (ground electrode) 15 connected to a ground wire is detachably mounted on the outer periphery of the front end portion of the gun body 2.
- the free ion removal electrode 15 is a two-part separation / detachable plate member, and is disposed in a wide range near the rear of the corona pin 8.
- the surface to be coated 21 of the non-conductive object to be coated 20 is weakly conductive in advance by antistatic treatment, and the grounding portion 23 of the non-conductive object to be coated 20 is connected to the ground wire and grounded.
- the antistatic treatment is performed by wiping an antistatic liquid (for example, a solution in which a quaternary ammonium salt surfactant is dissolved in about 0.1 to 10% in isopropyl alcohol) on the surface to be coated.
- an antistatic treatment film 24 is formed on the coated surface 21.
- Wipe application is wiping the coated surface 21 with a cloth impregnated with an antistatic liquid.
- the antistatic liquid is applied to the coated surface 21 by wiping, and dust or dirt adhering to the coated surface 21 is removed. Dust is wiped off.
- Wipe coating is a low-quality process in which uneven coating occurs, and the operation is extremely simple.
- the coating surface 21 of the non-conductive substrate 20 is applied by spray coating or dip coating in order to prevent deterioration in coating quality.
- a uniform continuous film is formed over the entire area 21.
- the corona discharge is mainly generated between the corona pin 8 and the free ion removing electrode 15, and the atomized paint particles discharged from the paint discharge port 29 fly while penetrating through the generated discharge area, thereby charging. Receive negatively charged.
- the charged paint particles are attracted by an electrostatic force formed between a positive charge appearing on the surface of the grounded object called a mirror effect and a negative charge of the paint particles, and reach the coated surface 21.
- the electric charge that has reached the surface to be coated 21 is discharged from the grounding portion 23 by the weak conductivity imparted by the applied conductive paint and the antistatic treatment film 24.
- the free ions that have not contributed to the charging of the conductive paint have a very small mass, and therefore fly almost inertially, fly to the free ion removing electrode 15 along the lines of electric force, and lose their charge. That is, free ions are reduced or removed by the free ion removing electrode 15.
- the charge carried by the paint particles to be applied mainly reaches the surface to be coated 21, and charging of the surface to be coated 21 due to the contact of air ionized by free ions is suppressed.
- the weak conductivity imparted by the coated conductive paint and the antistatic treatment film 24 is a surface resistance of about 700 M ⁇ / ⁇ immediately after the conductive paint is applied on the antistatic treatment film 24 to a thickness of about 30 ⁇ m. Value was confirmed. This is a much higher surface resistance value compared to metal coated objects (surface resistance value is almost zero ⁇ / ⁇ ) and coated objects coated with a conductive primer (surface resistance value is about 10 M ⁇ / ⁇ ). . Therefore, when electrostatic coating is performed without suppressing free ions, a large amount of charge is supplied to the non-conductive object 20 by the free ions, and the discharge of the charge from the ground portion 23 is not in time, so that non-conductive The workpiece 20 is charged to a high level.
- electrostatic repulsion causes electrostatic repulsion, and electrostatic repulsion can occur in various ways such as uneven coating thickness, poor coating coverage, thin coating, reduced coating efficiency, and blow back to coating equipment and painters.
- Invite the occurrence of various electrostatic coating defects It is difficult to manage the occurrence of such defects, especially in the case of large and complex non-conductive objects such as automobile radiator grills.
- the actual situation is that electrostatic coating is realized by imparting conductivity by mixing or imparting conductivity by applying a conductive primer.
- the charge of the non-conductive object 20 can be maintained at a low level by suppressing free ions, even a non-conductive object having a large and complicated shape can be used.
- the non-conductive object 20 can be electrostatically coated with a wide variety of paints.
- a conductive paint is used, corona discharge is not performed, a high voltage is directly applied to the conductive paint to charge the conductive paint negatively, and free ion generation itself is suppressed. Yes.
- the paint nozzle 3 of the spray gun 30 is made of a metal having substantially the same outer shape as the electrode outer cylinder 7 instead of the insulating resin electrode outer cylinder 7 of the first embodiment.
- the high voltage direct application electrode (high voltage electrode) 31 is provided.
- the rear end of the high voltage direct application electrode 31 is electrically connected to the connecting rod 6 via the spring 9, and the corona pin 8 as in the first embodiment is not provided.
- the DC high voltage is supplied from the cascade 5 through the connecting rod 6 and the spring 9 to the high voltage direct application electrode 31, and the conductive paint flowing through the hole 10 is applied by directly contacting the high voltage direct application electrode 31. Then, the conductive coating itself becomes a discharge electrode and carries a charge, and becomes a charged coating particle and is discharged from the discharge port 12 and atomized.
- 6 to 10 show that the injection of air from the air cap 4 which is a paint atomizing portion of the gun body is completely stopped, the applied voltage is fixed at 60 kV, and the volume specific resistance value of the conductive paint is changed. It is the photograph which image
- the coating liquid yarn at 200 M ⁇ cm is a water gun-like liquid yarn
- the coating liquid yarn at 100 M ⁇ cm is several cm after discharge. It can be seen that the liquid yarn is electrostatically repelled and split and atomized.
- spinous fission atomization occurs earlier because the voltage drop in the paint liquid yarn decreases and the effective voltage increases as the volume resistivity of the conductive paint decreases, and the spine becomes noticeable. I know that
- a high voltage is directly applied to negatively charge the conductive paint to suppress the generation of free ions. For this reason, corona discharge is unnecessary, and generation
- the simple structure of providing the high-voltage direct application electrode 31 in the hole (paint supply path) 10 suppresses the generation of free ions due to corona discharge and maintains the charging of the coated surface 21 at a low level. And good electrostatic coating can be performed continuously.
- a free ion removal electrode for reducing or removing the generated free ions is unnecessary, and cleaning and washing work of the free ion removal electrode does not occur.
- the discharge current can be kept low, and the capacity of the high voltage generator can be reduced.
- the high voltage direct application electrode 31 is not exposed to the outside, the occurrence of sparks is suppressed and the safety is improved.
- the water-soluble paint since the water-soluble paint has high conductivity, it can be used as the paint of this embodiment on condition that high voltage leakage prevention measures from the paint path are used.
- the first coating is applied to the coated surface 21 of the non-conductive coated object 20 by electrostatic coating of the first embodiment or the second embodiment, as shown in FIG.
- the first coating film 40 is formed (first coating step), and then the second coating is applied to the first coating by the same electrostatic coating (the electrostatic coating of the first or second embodiment). It is applied to the surface 41 of the film 40 to form a second coating film 42 (second coating process).
- the application of the second paint is performed before the first coating film 40 is dried. Since the surface 41 of the first coating 40 before drying is weakly conductive, the second coating can be electrostatically applied in the same manner as the first coating, and a plurality of coatings can be easily formed. Can be repainted. That is, over-coating on the surface to be coated can be performed easily, reliably and safely by good electrostatic coating while suppressing an increase in man-hours and costs without causing complication of work. .
- the third coating 44 is formed.
- the fourth coating is applied to the surface 45 of the third coating 44 to form a fourth coating (not shown). (4th painting process).
- the coating by electrostatic coating of the present embodiment is performed by, for example, a PP primer and a base coat by a wet-on-wet method called 3-coat 1-bake on a PP (polypropylene) resin base material, which is most frequently used in front bumpers and rear bumpers of automobile bodies.
- 3-coat 1-bake on a PP (polypropylene) resin base material, which is most frequently used in front bumpers and rear bumpers of automobile bodies.
- 3 layers of clear coat can be applied to a coating system in which multiple layers are coated and dried.
- the non-conductive object 20 is a PP resin substrate
- the first paint is a PP primer
- the second paint is a base coat
- the third paint is a clear coat.
- a 500 cc PET bottle was used as the non-conductive substrate, and the automatic spray gun for electrostatic coating attached to the reciprocator was reciprocated three times in the vertical direction to apply the paint only within the range of the PET bottle. It was discharged and electrostatic coating was performed. At that time, the movement of the spray gun was set so that the conductive paint was spread from the vicinity of the grounded portion of the coated surface.
- the high voltages applied to the conductive paint are 0 kV, 30 kV, 60 kV, and 90 kV.
- the conductive paint used was obtained by adding a conductive agent to a two-component urethane paint, and the volume specific resistance value was 1 M ⁇ cm. A quaternary ammonium salt 0.35% isopropyl alcohol solution was wiped onto the surface (coating surface) of the PET bottle.
- the results of the effect confirmation experiment 1 are shown in Table 1 of FIG. From this result, the following can be understood.
- the first embodiment corresponds to a corona discharge at 60 kV + free ion removal electrode
- the second embodiment corresponds to direct application at 60 kV.
- the coating efficiency has been greatly improved from 4.7% to 23.7% and 27.0%, respectively. It is possible to greatly reduce the amount of paint discarded.
- the throwing around the back surface of the plastic bottle (the back coating state) is good, and it is possible to omit the coating facing the side surface and the back surface. For this reason, it is possible to significantly reduce the paint locus (shortening the painting time).
- the painting current value is greatly reduced as compared with the first embodiment, and the high voltage generator can be reduced in size (reduced capacity) by reducing the current.
- the high voltage applied to the conductive paint was set to 60 kV, and the volume resistivity of the conductive paint was changed from 200 M ⁇ cm to 0.5 M ⁇ cm, and the coating efficiency was measured.
- the volume resistivity value of the conductive paint is preferably 100 M ⁇ cm or less, and more preferably 20 M ⁇ cm or less.
- a coating system (3 coats and 1 bake coating on the resin substrate) in which three layers of PP primer, base coat, and clear coat are applied to the PP resin substrate and dried, all three layers are not used in conventional general coating.
- Applying electrostatic coating or non-electrostatic coating of PP primer with high conductivity (surface resistance: about 10M ⁇ / ⁇ ), base coat (2nd layer) and clear coat (3rd layer) are conventional technologies It is done by electrostatic painting.
- the object to be coated is the ground electrode
- the electrode on the coating apparatus side is the cathode
- an electrostatic field (electric field lines) is formed by applying a high voltage between them.
- This is a coating method in which paint particles are charged negatively and the paint is applied to the object by electrostatic force, and a high voltage is applied between the object to be coated and the coating equipment to actively form an electrostatic field.
- it is essentially different from the electrostatic coating of the present embodiment.
- the coating method of this embodiment has a weak conductivity of about 1 to 10 G ⁇ / ⁇ in a wet state before drying coated with a conductive paint (volume specific resistance value 1 M ⁇ cm). ) Is a multilayer electrostatic coating method in which free ion suppression means is added to electrostatic coating.
- the conventional general coating and the multilayer electrostatic coating of this embodiment were compared with respect to the base coat coating (two-layer wet-on-wet multilayer electrostatic coating) corresponding to the second layer of the multilayer electrostatic coating. .
- Non-electrostatic coating was adopted as the conventional coating.
- non-electrostatic coating the entire surface of the object to be coated (undried wet with PP primer applied, with weak conductivity) is rotated by hand like a potter's wheel.
- a base coat paint paint (paint volume specific resistance value 1 M ⁇ cm) was applied like a spray pattern with non-electrostatic (high voltage 0 kV) using a paint direct application type air spray electrostatic hand gun.
- the base coat paint is applied only from the front without rotating the object to be coated with a spray pattern in which a high voltage of 60 kV is directly applied inside the gun. Compared to the case.
- the comparison results are as follows.
- Non-electrostatic coating for comparison (high voltage 0 kV spray) Coating time required for full surface coating: 60 seconds (25 reciprocating coatings while rotating the object to be coated) Amount of paint used to paint the entire surface: 160cc
- Electrostatic coating of this embodiment (high voltage 60 kV spray) The painting time required for the entire painting: 11 seconds (3 reciprocating paintings from the front of the object only) The amount of paint used to paint the entire surface: 30cc Overall painting coverage: Good (3) Consideration of effect In the electrostatic coating of this embodiment, compared to the conventional non-electrostatic coating, both the painting time and the amount of paint used are reduced by about 80%, and the painting time is shortened. In addition, a great effect was observed in reducing the amount of paint used. In this experiment, the base coat of the second layer was confirmed, but the same effect can be obtained even when the third layer is cleared and the fourth and subsequent layers are applied.
- a conductive primer surface resistance value, about 10 M ⁇ / ⁇
- the paint unit price can be reduced.
- it is a coating system that electrostatically coats in a semiconductor state whose surface resistance value is 100 to 1000 times higher than that of the conductive primer and gives only a minimum charge in a free ion suppression state, the ground of the object to be coated is insufficient. The risk of floating conductor charging sparks generated in the case is reduced.
- the present invention can also be applied to a coated material made of a weakly conductive material. .
- electrostatic coating can be performed without considering the application of weak conductivity to the surface to be coated.
- weak electroconductivity is provided to the to-be-coated surface 21 by both the antistatic process of the to-be-coated surface 21 by application
- weak conductivity may be imparted to the coated surface 21 by only one of them, or weak conductivity may be imparted to the coated surface 21 by other methods.
- the air spray type spray gun 1 is used as the electrostatic coating gun. Instead, an airless type spray gun that performs corona discharge is used. Also good.
- the air spray type spray gun 30 has been described as an electrostatic coating gun that is negatively charged by directly applying a high voltage to the conductive coating material.
- the gun is not limited to this, but an internal structure for directly applying a high voltage to the conductive paint to make it negatively charged and a high-voltage applying conductor for generating free ions (corona electrode pin, metal bell cup, It may be an airless spray gun or a rotary atomizing gun having a structure in which a metal spray cap, a metal spray nozzle, etc.) are insulated.
- the paint particles are negatively charged using the electrode on the coating apparatus side as the cathode.
- the paint particles may be charged positively using the electrode on the coating apparatus side as the anode.
- the first coating process is not limited as long as the first paint having conductivity is applied to the coated surface 21, and the coating method is arbitrary.
- the first paint may be applied by non-electrostatic air spray, or the first paint may be applied by a cloth or a brush.
- the coated surface 21 having weak conductivity has been described.
- the coated surface may have insulating properties, and only the first paint is used in the static coating of the above-described embodiment. It may be a single layer coating applied by electropainting.
- the coated surface having insulating properties is grounded, and the first paint is sequentially applied from the grounded side of the coated surface.
- electrostatic coating of the coated surface is performed in a state where free ions are suppressed, and the suppression of free ions reduces the amount of ions reaching the coated surface. Suppresses charging of the coated surface. For this reason, the charging of the coated surface can be maintained at a low level, and electrostatic coating can be continuously performed.
- the present invention can be widely used for electrostatic coating of non-conductive or weakly conductive objects.
- Spray gun electrostatic coating gun
- Gun body 3 Paint nozzle 4: Air cap 5: Cascade (high voltage generator) 7: Electrode outer cylinder 8: Corona pin 10: Hole (paint supply path) 12: Discharge port 15: Free ion removal electrode (ground electrode) 20: Non-conductive object to be coated 21: Surface to be coated 23: Grounding portion 24: Antistatic treatment film 30: Spray gun (electrostatic coating gun) 31: High voltage direct application electrode 40: 1st coating film 41: 1st coating film surface 42: 2nd coating film 43: 2nd coating film surface 44: 3rd coating film 45: 3rd The surface of the coating
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- Electrostatic Spraying Apparatus (AREA)
Abstract
Description
・導電材又は導電剤の混入による素材への導電性付与。
・導電プライマーなどの導電膜の塗布による被塗面への導電性付与。
・界面活性剤の塗布などの帯電防止処理による被塗面への一時的な弱導電性付与。
・被塗面の接地及び導電性塗料の使用による被塗面への弱導電性付与。
・導電性物質を被塗物裏面に塗布すること又は接近させることによる静電容量の上昇(帯電量に対する電位降下)。
以下、スプレーガンの第1の形態例を図面を参照して説明する。なお、以下の説明における上下は、図1中の上下方向に対応し、前後は、図1中の左右に対応する。
次に、スプレーガンの第2の形態例を図面を参照して説明する。なお、以下の説明における上下は、図2中の上下方向に対応し、前後は、図2中の左右に対応する。また、第1の形態例と共通する構成については、同一の符号を付してその説明を省略する。
本実施形態では、第1の形態例又は第2の形態例の静電塗装によって、図11に示すように、第1の塗料を非導電性被塗物20の被塗面21に塗布して第1の塗膜40を形成し(第1の塗装工程)、次に、同様の静電塗装(第1又は第2の形態例の静電塗装)によって、第2の塗料を第1の塗膜40の表面41に塗布して第2の塗膜42を形成する(第2の塗装工程)。第2の塗料の塗布は、第1の塗膜40が乾燥する前に行う。乾燥前の第1の塗膜40の表面41は弱導電性を有するため、第2の塗料を第1の塗料の場合と同様に静電塗装することができ、複数層の塗膜を簡単に塗り重ねることができる。すなわち、作業の煩雑化を招くことなく、工数の増加やコストの上昇を抑制しつつ、被塗面への重ね塗りを、良好な静電塗装によって簡単に、確実に且つ安全に行うことができる。
次に、効果確認実験1について説明する。
次に、効果確認実験2について説明する。
次に、効果確認実験3について説明する。
次に、効果確認実験4について説明する。
(1)比較対象とした非静電塗装(高電圧0kVスプレー)
全面塗装に要した塗装時間:60秒(被塗装物を回転させながら、25往復塗装)
全面塗装に要した塗料使用量:160cc
(2)本実施形態の静電塗装(高電圧60kVスプレー)
全面塗装に要した塗装時間:11秒(被塗装物の前面のみから3往復塗装)
全面塗装に要した塗料使用量:30cc
全面塗装つきまわり状況:良好
(3)効果考察
本実施形態の静電塗装では、従来の非静電塗装と比較して、塗装時間及び塗料使用量ともに約80%低減しており、塗装時間短縮及び塗料使用量低減に大きな効果が認められた。なお、この実験では、2層目のベースコートについて確認したが、3層目のクリアや更に4層目以降を塗装する場合でも同様の効果がある。
2:ガン本体
3:ペイントノズル
4:エアキャップ
5:カスケード(高電圧発生装置)
7:電極外筒
8:コロナピン
10:孔(塗料供給路)
12:吐出口
15:フリーイオン除去電極(接地電極)
20:非導電性被塗物
21:被塗面
23:接地部
24:帯電防止処理皮膜
30:スプレーガン(静電塗装用ガン)
31:高電圧直接印加電極
40:第1の塗膜
41:第1の塗膜の表面
42:第2の塗膜
43:第2の塗膜の表面
44:第3の塗膜
45:第3の塗膜の表面
Claims (3)
- 導電性を有する第1の塗料を被塗面に塗布して第1の塗膜を形成する第1の塗装工程と、
前記第1の塗膜が乾燥する前に、マイナスに帯電した第2の塗料を、フリーイオンを抑制した状態で前記第1の塗膜の表面に塗布して第2の塗膜を形成する第2の塗装工程と、を備えた
ことを特徴とする塗装方法。 - 請求項1に記載の静電塗装方法であって、
前記被塗面は、弱導電性又は絶縁性を有し、
前記第1の塗装工程では、マイナスに帯電した前記第1の塗料を、フリーイオンを抑制した状態で前記被塗面に塗布する
ことを特徴とする静電塗装方法。 - 絶縁性を有する被塗面の静電塗装方法であって、
マイナスに帯電した塗料を、フリーイオンを抑制した状態で前記被塗面に塗布する
ことを特徴とする静電塗装方法。
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US14/361,511 US9724728B2 (en) | 2011-11-30 | 2012-11-29 | Electrostatic coating method |
CN201280059101.5A CN103958074B (zh) | 2011-11-30 | 2012-11-29 | 静电涂装方法 |
EP12853906.1A EP2786806A4 (en) | 2011-11-30 | 2012-11-29 | ELECTROSTATIC COATING PROCESS |
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JP2011261794A JP5854322B2 (ja) | 2011-11-30 | 2011-11-30 | 静電塗装方法 |
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US (1) | US9724728B2 (ja) |
EP (1) | EP2786806A4 (ja) |
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JP2017136550A (ja) * | 2016-02-03 | 2017-08-10 | ランズバーグ・インダストリー株式会社 | 合成樹脂成型品の静電塗装方法 |
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JP2015089544A (ja) * | 2013-11-07 | 2015-05-11 | 旭サナック株式会社 | 溶接金属製品の静電塗装方法 |
WO2017170344A1 (ja) * | 2016-03-28 | 2017-10-05 | 本田技研工業株式会社 | 塗装装置および塗装方法 |
JP2020065983A (ja) * | 2018-10-25 | 2020-04-30 | 株式会社大気社 | 直接帯電方式の溶剤系塗料使用静電塗装方法及び静電塗装装置 |
CN110665770A (zh) * | 2019-11-12 | 2020-01-10 | 徐詹程 | 一种多层膜干化学试剂片的制作方法 |
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JP5854322B2 (ja) | 2016-02-09 |
CN103958074B (zh) | 2016-05-04 |
JP2013111554A (ja) | 2013-06-10 |
CN103958074A (zh) | 2014-07-30 |
EP2786806A4 (en) | 2016-06-29 |
US9724728B2 (en) | 2017-08-08 |
US20140335284A1 (en) | 2014-11-13 |
EP2786806A1 (en) | 2014-10-08 |
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