JP2002097596A - Electrocoating equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide electrocoating equipment which can achieve a homogeneous electrocoating without influence of contamination caused by inadequate cleaning in a pretreatment process and is attached to an article to be coated. SOLUTION: The electrocoating equipment provided with an electrodeposition tank 2 for accommodating a liquid electrocoating 1, a transportation means 4 for putting the article 3 into the electrodeposition tank 2 and putting it out after electrocoating, and an electrifying means for depositing the electrocoating 1 on the surface of the article 3 by means of applying a direct current voltage between the article 3 and an electrode plate 17, so as to make the article 3 which is put into the electrodeposition tank 2 and dipped in the electrocoating 1, to be one anode, and so as to make the electrode plate 17 which is arranged in the electrodeposition tank 2 separately from the article to be coated 3, to be the other electrode, is characterized by an electrocoating discharging means 40 for discharging the electrocoating 1 towards the article 3 in the electrodeposition tank 2, while the article 3 is dipped in the electrocoating 1 after it has been put in the electrodeposition tank 2 and before an electrodeposition is substantially started.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodeposition coating apparatus for applying an electrodeposition coating to an object immersed in an electrodeposition tank by using an electrodeposition coating material filled in the electrodeposition tank. More specifically, the present invention relates to an electrodeposition coating apparatus capable of providing a uniform coating film regardless of the influence of contamination attached to an object to be coated.

[0002]

2. Description of the Related Art In general, electrodeposition coating is easy in automation of a coating process, good in coating property of a coating material to be coated, a coating film having a uniform film thickness is obtained, and furthermore, a water-based coating material is used. Therefore, it has advantages such as low environmental load and high safety, and has been widely used in industrial coating lines and the like. As the electrodeposition coating, an anodic electrodeposition coating is used in which an anion electrodeposition coating is used as an electrodeposition coating and electrodeposition is performed using an object to be coated made of a conductive material as an anode, and a cationic electrodeposition coating is used as the electrodeposition coating. Cathodic electrodeposition coating in which electrodeposition is performed using an object to be coated made of a conductive material as a cathode.

In recent years, in various coating lines, cathodic electrodeposition has been surpassing anodic electrodeposition. This is because the cathodic electrodeposition coating does not cause the substrate to be coated to be a cathode, so that the base material to be coated does not dissolve, and the corrosion resistance of the surface of the substrate to be coated is enhanced by the amino groups contained in the cationic electrodeposition coating. It is based on having various advantages such as. Therefore, in general, cathodic electrodeposition coating is generally performed for anticorrosion coating, which is a base coating for an automobile body.

[0004] The conductive material as the object to be coated is generally made of iron, aluminum, zinc, or an alloy thereof, and dust remaining on the surface thereof before being subjected to electrodeposition coating, rolling oil, cutting oil, or the like. In order to remove various oils such as press oil or rust-preventive oil, to provide primary rust-preventive properties on the surface, and to improve the adhesion with paint, a cleaning degreasing step and a chemical conversion treatment step such as phosphate Pre-processing including the above is performed.
The object to be coated after pre-treatment is originally a clean surface with high hydrophilicity covered with a film such as a phosphate film, and when subjected to electrodeposition coating, the surface uniformly contacts the paint. As a result, a uniform coating film is formed.

[0005] However, in particular, when the object to be coated has a complicated shape such as an automobile white body, a partial stripe-like repelling unevenness may be observed in the coating film after the electrodeposition coating. This is not sufficiently degreased in the pre-treatment washing and degreasing step, and is subjected to electrodeposition coating in a state where various oils adhere to the object to be coated as it is, and as a result, the affinity with the electrodeposition paint is poor at the relevant place, It is thought to be due to hajikimura.

[0006] Such cissing unevenness may be solved by strengthening the pre-treatment washing and degreasing step. However, high-viscosity oil is used at the time of molding an object to be coated, or after rolling or press molding. If the leaving environment (temperature, presence or absence of sunlight, leaving time, etc.) is bad, it is difficult to completely eliminate the influence in the washing and degreasing step. Therefore, it has been desired to cope with the repelling unevenness of the object to be coated even in a step other than the pretreatment.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a uniform electrodeposition coating regardless of the effects of contaminants adhering to an object to be coated, which have not been sufficiently cleaned and degreased in a pretreatment step. An object of the present invention is to provide an electrodeposition coating apparatus capable of providing a coating film.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the above-mentioned problems, and as a result, the above-mentioned problems have been solved by causing an electrodeposition paint to collide with an object to be coated before energization in an electrodeposition tank. They have found that they can do this, and have come to the present invention.

That is, the first aspect of the present invention provides at least
An electrodeposition tank containing a liquid electrodeposition coating material, and a transporting means for causing the object to be coated to enter the electrodeposition tank and to leave after the electrodeposition coating,
The object to be coated, which is immersed in the electrodeposition paint after being immersed in the electrodeposition tank, serves as one electrode, and an electrode plate disposed apart from the object in the electrodeposition tank. Current applying means for applying a DC voltage between the object to be coated and the electrode plate to electrodeposit the electrodeposition paint on the surface of the object to be coated so as to be the other electrode. A coating apparatus,
Further, after the object to be coated is placed in the electrodeposition tank and immersed in the electrodeposition coating, before the electrodeposition is substantially started, the object to be coated is placed in the electrodeposition tank. An electrodeposition coating apparatus characterized in that an electrodeposition coating material discharging means for discharging the electrodeposition coating material is provided.

According to the electrodeposition coating apparatus of the first aspect of the present invention, it is possible to eliminate the streak-like uneven spots which are not sufficiently cleaned and degreased in the pretreatment step and are considered to be caused by the contamination attached to the object to be coated. Or can be suppressed. This is because the contaminants are washed away by physically colliding the electrodeposition paint with the place where the adhesion and the adhesion with the electrodeposition paint are reduced, and the familiarity improves even if it can not be completely washed off,
It is presumed that this is because uniform energization becomes possible by applying electricity after that and performing electrodeposition coating.

According to a second aspect of the present invention, there is provided the electrodeposition coating apparatus according to the first aspect of the present invention, wherein the electrodeposition tank has a boat shape or a rectangular parallelepiped shape, and the transport means transports the object to be coated by the electrodeposition. A continuous conveying means which enters the tank from one end in the longitudinal direction of the tank, advances in the longitudinal direction in the electrodeposition tank, and leaves the tank from the other end in the longitudinal direction of the electrodeposition tank, and successively sequentially performs this. Wherein the energizing means is means for applying a DC voltage between the object to be coated and the electrode plate while the object to be coated is moving in the electrodeposition tank in the longitudinal direction. And According to the second aspect of the present invention, the functions and effects of the first aspect of the present invention are exhibited in an electrodeposition coating apparatus using a continuous transfer device employed in an automobile body painting line or the like. Therefore, an object to be coated with a uniform coating film can be continuously and efficiently produced.

According to a third aspect of the present invention, there is provided the electrodeposition coating apparatus according to the second aspect of the present invention, wherein the electrodeposition paint discharging means discharges the electrodeposition paint toward the object by the electrodeposition paint discharge means. It is a peripheral portion of one end where the object to be coated in the longitudinal direction of the electrodeposition tank enters the tank. According to the third aspect of the present invention, in the electrodeposition coating apparatus using the continuous transport device, before the object to be coated reaches a position where an electrode to which a current is normally supplied is arranged,
Since the electrodeposition paint can be made to collide with the object to be coated around the so-called tank section, the arrangement efficiency of each means is good, and it does not affect the electricity supply for electrodeposition coating, and continuous production The operation and effects of the second aspect of the present invention are exhibited without any trouble.

According to a fourth aspect of the present invention, there is provided the electrodeposition coating apparatus according to the second or third aspect, wherein the electrodeposition paint discharging means discharges the electrodeposition paint toward the object by the electrodeposition paint discharge means. Are on both the left and right sides in the traveling direction of the object to be coated. According to the fourth aspect of the present invention, the electrodeposition paint can be made to collide from both the left and right sides of the article to be coated in the electrodeposition tank. It is possible to solve cissing unevenness in a wide area and / or an appropriate place of the coating material.

According to a fifth aspect of the present invention, there is provided the electrodeposition coating apparatus according to any one of the first to fourth aspects, wherein the electrodeposition coating material discharging means is provided with the coating material immersed in the electrodeposition coating material. One or more nozzles whose discharge ports are directed to an object, a pump that takes in the electrodeposition paint held in the electrodeposition tank and feeds the nozzle, and a liquid feed pipe that connects the pump and the nozzle. , And is characterized by. According to the fifth aspect of the present invention, since the electrodeposition paint is discharged onto the object to be coated using the nozzle, it is possible to cause the electrodeposition paint of sufficient pressure and amount to collide with the object to be applied, and Since the configuration is simple and it is easy to adjust the discharge direction of the electrodeposition paint, it is possible to solve the cissing unevenness at an appropriate place on the object to be coated.

According to a sixth aspect of the present invention, there is provided the electrodeposition coating apparatus according to the fifth aspect of the present invention, wherein the nozzle has a gap between an outlet of the nozzle and the object immersed in the electrodeposition coating. ~ 50cm
Is arranged in the electrodeposition tank so as to fall within the range of (1). According to the sixth aspect of the present invention, the distance between the object to be coated and the discharge port of the nozzle is appropriate, and the electrodeposited paint of an appropriate pressure and amount can collide with the object to be coated.

According to a seventh aspect of the present invention, there is provided the electrodeposition coating apparatus according to the fifth or sixth aspect, wherein the nozzle has a depth of 20 to 50 cm from the liquid level of the electrodeposition coating. It is characterized by being disposed in an electrodeposition tank. According to the seventh aspect of the present invention, since the arrangement of the nozzles is appropriate, it is possible to cause the electrodeposition paint to collide with a large area of the object to be coated, generate a wave on the liquid surface by the liquid flow, The operation and effect of the fifth or sixth aspect of the present invention is exhibited without the electrodeposition paint 1 scattering.

According to an eighth aspect of the present invention, in any one of the fifth to seventh aspects,
The discharge pressure of the electrodeposition paint from the nozzle is in a range of 0.05 to 0.1 MPa. According to the eighth aspect of the invention, the discharge pressure of the electrodeposition paint from the nozzle is appropriate, and the electrodeposition paint can be made to collide with the object to be coated at an appropriate pressure.

The ninth invention is directed to any one of the fifth to eighth inventions
The electrodeposition coating apparatus of the present invention, wherein the nozzle is an ejector type nozzle. The ejector-type nozzle has a configuration in which the surrounding electrodeposition paint is wrapped and ejected when ejected, so if the ejector-type nozzle is used, even if the pump capacity is small, a larger amount of the electrodeposition paint can collide, and the ejection efficiency can be improved. Is good. Therefore, according to the ninth aspect of the present invention, it is possible to provide an electrodeposition coating apparatus which can easily exhibit the effects of any one of the fifth to eighth aspects of the present invention.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below with reference to an embodiment of an electrodeposition coating apparatus provided with a continuous transport device. FIG. 1 is a top view of an electrodeposition coating apparatus SP according to an embodiment of the present invention, in which the configuration outside the electrodeposition tank 2 is omitted. FIG. 2 is a diagram showing A in FIG.
FIG. 2 is a cross-sectional view of FIG. 1, illustrating a transporting device-related (including an object to be coated 3) in a configuration outside the electrodeposition tank 2 omitted in FIG. 1. FIG. 3 is a sectional view taken along line BB in FIG.
In addition to the outline of the transporting apparatus, a schematic configuration for explaining the circulation state of the electrodeposition liquid and the electric circuit in the electrodeposition coating apparatus SP, including the external configuration of the electrodeposition tank 2, is added.

An electrodeposition coating apparatus SP for electrodepositing a primer (electrodeposition paint) on an object to be coated such as a white body of an automobile is substantially a boat-shaped holding liquid (cation) electrodeposition paint 1. and electrodeposition tank 2 of a conductive material (e.g., iron, aluminum, galvanized etc.) coated article comprising a conveying mechanism 4 for transporting the 3 (white automobile body) in the arrow Y ₁ to Y ₃ direction, the minus side Coating object 3 functioning as an electrode
And an energizing mechanism (energizing means) 5 for applying a DC voltage between the plus side electrodes (side electrode plate 17 and bottom electrode plate 18 described later), and is immersed in the electrodeposition paint 1. A coating film component in the electrodeposition paint 1 (which means all components that finally form a coating film in the electrodeposition paint) is attached (electrodeposited) on the surface of the article 3 to be coated. .

In the following description, for the sake of convenience, the object 3 is viewed in the transport direction of the object 3 (directions of arrows Y _{1 to} Y ₃ ).
The side into which the substrate 3 enters the electrodeposition tank 2 (the right side in the positional relationship in FIG. 1) is referred to as the “entrance side”, and the side from which the article 3 exits the electrodeposition tank 2 (the positional relationship in FIG. 1). The left side will be referred to as the “outside tank side”.

An entrance-side inclined portion 7 having an inclined bottom is provided at the entry-side end 6 of the electrodeposition tank 2 adjacent to the entry-side end 6. A flat bottom 8 having a bottom is provided. On the entry side of the exit side end 10 of the electrodeposition tank 2, an exit side inclined portion 9 having an inclined bottom is provided adjacent to the exit side end 10.

As shown in FIG. 2, the electrodeposition tank 2 of the present embodiment is not completely boat-shaped, but the bottom of the coating object 3 on the entry and / or exit sides is A shape that rises toward the end is included in the category of “boat” defined in the present invention. Further, in the present invention, the shape of the electrodeposition tank is not limited to a boat shape, but may be a rectangular parallelepiped shape or the like. Here, the “cuboid shape” defined in the present invention is included in the category as long as the entire tank is substantially in the shape of a rectangular parallelepiped, and does not take into account some structural deformation.

The transport mechanism 4 includes a rail 11 extending above the electrodeposition tank 2 from the entry side to the exit side, and a plurality of transporters 12 movable along the rail 11.
And a carrier 13 which is attached to each transporting device 12 and on which the article 3 can be placed.

Each transfer device 12 is mounted on a rail 11 respectively.
Arrow Y at a given speed along₁, Y_Two, Y_ThreeMove in the direction indicated by
Move. Here, the vertical direction of the rail 11 is roughly
It is undulated corresponding to the undulation of the bottom surface of the electrodeposition tank 2. this
Therefore, each transfer device 12 has an arrow Y ₁, Y_Two, Y_ThreeIn the direction indicated by
When it moves, it is attached to the transporter 12.
The objects to be coated 3 placed on the carrier 13 are respectively electrodeposited.
The electrodeposition paint is put into the electrodeposition tank 2 above the inclined portion 7 on the inlet side of the tank 2 and
1 begins to be immersed in the flat bottom 8 near its outlet side
Except for, proceed while completely immersed in electrodeposition paint 1
From the vicinity of the bottom end of the flat bottom 8 to the exit side slope 9
At the part of the electrode, it comes out of the electrodeposition tank 2 and comes out of the electrodeposition paint
Will come out. In this way, each carrier 13
The coated object 3 is sequentially and continuously electrodeposited in the electrodeposition tank 2.
Immerse in paint 1 for a predetermined time and apply electrodeposition coating
You.

The power supply mechanism (power supply means) 5 is provided with a DC power supply 15 capable of outputting a DC voltage, and a negative output terminal of the DC power supply 15 is connected via a negative conductor 16 and a transport elevating mechanism (not shown). And is electrically connected to the carrier 12. Since the transporter 12 and the carrier 13 are each formed of a conductive material, the object 3 immersed in the electrodeposition paint 1 in the electrodeposition tank 2 includes the carrier 13, the transporter 12, and the negative conductor 16. DC power supply 1 via
5 is electrically connected to the minus output terminal. Therefore, the object 3 made of a conductive material functions as a cathode in the electrodeposition coating.

Further, in the electrodeposition bath 2, a plurality of side electrode plates 17 and a plurality of bottom electrode plates 18 functioning as anodes in the electrodeposition coating are provided. Here, the side electrode plates 17 are arranged on both sides of the article 3 in a state of being completely immersed in the electrodeposition paint 1 so as to be appropriately separated from the article 3. On the other hand, the bottom electrode plate 18 is disposed below the object 3 in a state of being completely immersed in the electrodeposition paint 1 so as to be appropriately separated from the object 3. Then, the side electrode plate 17 and the bottom electrode plate 18
Are connected to the DC power source 1 via the positive conductor 19, respectively.
5, and is electrically connected to the positive output terminal of No. 5 so as to function as an anode in electrodeposition coating.

The side electrode plate 17 is disposed in the diaphragm chamber 20. That is, the diaphragm 21 formed or arranged so as to surround the side electrode plate 17 to protect the side electrode plate 17 is provided, and the diaphragm chamber 20 is configured.

Outside the electrodeposition tank 2, a predetermined amount of the diaphragm solution 23
Is provided, a diaphragm liquid tank 22 capable of holding
The diaphragm solution 23 held in the diaphragm solution tank 22
And the electrodeposition paint 1 held in the diaphragm chamber 20 surrounded by the diaphragm 21 of the electrodeposition tank 2 by the pump 24
The first diaphragm liquid pipe 25 and the second diaphragm liquid pipe 26 can be circulated between the two. Here, pure water 28 stored in a pure water tank 27 is supplied to the diaphragm liquid tank 22 via a pure water supply passage 29. The pure water supply passage 29 is provided with a control valve 31 for controlling the flow rate of the pure water 28 flowing through the pure water supply passage 29, and the value of the electrodeposition paint 23 detected by the electric conductivity meter 30. The control valve 31 is feedback-controlled by the controller 32 based on the
3 is maintained within a predetermined range.

In the electrodeposition coating apparatus SP, in order to make the distribution or dispersion of each component in the electrodeposition coating 1 held in the electrodeposition tank 2 uniform, the electrodeposition coating 1 is stirred by flow stirring. An agitation mechanism 35 is provided.

The fluid type stirring mechanism 35 is provided with a receiving tank 37 for receiving the electrodeposition paint 1 overflowing from the electrodeposition tank 2, and the electrodeposition paint 1 in the receiving tank 37 is pressurized by a circulation pump 38. Is supplied to the riser 40 disposed near the bottom of the electrodeposition tank 2 through the electrodeposition paint circulation pipe 39, and the rise of the electrodeposition paint 1 in the electrodeposition tank 2 from the riser 40.
It can be squirted inside.

In the present embodiment, the electrodeposition paint circulation pipe 39 is provided with a filter 41 for removing foreign substances in the electrodeposition paint 1 and the flow rate of the electrodeposition paint 1 flowing through the electrodeposition paint circulation pipe 39 is adjusted. And a liquid temperature adjusting device (heat exchanging means) 43 for adjusting the temperature of the electrodeposition paint 1 flowing in the electrodeposition paint circulation pipe 39.
These configurations are, of course, optional elements in the present invention.

In the electrodeposition paint circulation pipe 39, U
It is desirable that an F device (UF filtering means) is provided. In this embodiment, the UF device is desirably provided downstream of the liquid temperature adjusting device 43 in the electrodeposition paint circulation pipe 39. In a UF device (UF filtration means), only water, ions, and low molecular substances are passed through a myriad of fine pores of a semipermeable membrane by applying pressure to the semipermeable membrane from a liquid containing a polymer substance or a colloidal substance. By permeating and separating, and using the permeate for washing with water, the electrodeposition process can be closed and the amount of paint taken out can be reduced.

The electrodeposition paint 1 ejected from the riser 40 into the electrodeposition tank 2 flows into the electrodeposition tank 2 toward the receiving tank 37 at the lower part of the electrodeposition tank 2 while flowing toward the receiving tank 37 side. In such a case, a circulating flow is generated such that the electrodeposition paint 1 in the electrodeposition tank 2 is stirred.

Next, the means for discharging electrodeposition paint characteristic of the present invention will be described. As shown in FIGS. 1 and 2, the electrodeposition paint discharging means 40 includes a riser 44, a plurality of nozzles 45 arranged at regular intervals in a longitudinal direction of the riser 44,
A pump 46 for feeding the electrodeposition paint 1 to the riser 44, a space between the electrodeposition tank 2 and the pump 46, and
And liquid feed pipes 47 and 47 'connecting the spaces, respectively.

The riser 44 is located near the left and right sides of the electrodeposition tank 2 in the conveying direction of the object 3 (in the directions of arrows Y _{1 to} Y ₃ ) and is below the liquid level, at the entrance of the tank-side end 6. It is installed from the side inclined part 7 to the flat bottom part 8. A plurality of nozzles 45 arranged in the riser 44, the conveying direction of the article to be coated 3 (arrow Y ₁ ~
Y ₃ direction) substantially perpendicular to the discharge port from the left and right side surfaces as viewed in is directed, has a structure which can substantially is vertically collide with the electrodeposition paint 1 for the coating object 3 which has been Iriso.

One end of the liquid feed pipe 47 is connected to the flat bottom 8 of the electrodeposition tank 2, and the other end is connected to the liquid suction side of the pump 46. However, one end of the liquid sending pipe 47 does not necessarily need to be connected to the flat bottom portion 8 of the electrodeposition tank 2, and is held by another part of the electrodeposition tank 2 or the electrodeposition tank 2 such as an overflow tank (not shown). It may be connected to any place as long as it can take in the electrodeposition paint 1. Alternatively, the circulation pump 38 may also have a role of a pump 46 by branching from a normal stirring system pipe (such as the electrodeposition paint circulation pipe 39 in FIG. 3). It is desirable to use a sufficiently large pump pressure. If the pump itself is replaced with a submersible pump and is installed at an appropriate position in the electrodeposition tank 2, the liquid sending pipe 47 is omitted.

One end of the liquid sending pipe 47 ′ is connected to the pump 46.
And the other end is branched into two risers 4
4 at the end. When the pump 46 operates, the electrodeposition coating material 1 held in the electrodeposition tank 2 is taken in through the liquid sending pipe 47, sent to the riser 44 through the liquid sending pipe 47 ′, and discharged from each nozzle 45. Is discharged from. Then
The electrodeposition paint 1 collides substantially perpendicularly with the article 3 to be coated.

As described above, the electrodeposition paint 1
According to the electrodeposition coating apparatus of the present embodiment provided with the electrodeposition paint discharging means 40 for discharging the electrodeposition, the electrodeposition is substantially started after the object 3 is immersed in the electrodeposition paint 1. In the meantime, the electrodeposition paint 1 is caused to physically collide with the object 3 to be washed and degreased sufficiently in the pretreatment process, which is considered to be due to the contamination attached to the object to be coated. Streak-like repelling unevenness can be eliminated or suppressed.

In the present invention, the phrase “electrodeposition is substantially started” does not mean that a DC voltage is applied between the object to be coated and the electrode. , And a substantially sufficient film-forming reaction is started. Therefore, in the case of the continuous electrodeposition coating apparatus as in the present embodiment, the leading end of the object 3 reaches the vicinity of the side electrode plate 17 and the current is applied between the object 3 and the side electrode plate 17. Is started, the coating film forming reaction is not sufficiently started substantially behind the object 3 to be hit by the electrodeposition paint 1 by the electrodeposition paint discharging means 40, and the present invention It is included in the category.
Furthermore, even if the configuration is such that the substrate 3 is placed in a conducting state between the substrate 3 and the side electrode plate 17 in advance before the substrate 3 is placed in the tank, the substrate 3 is placed at the top of the substrate 3. Is not in a state where “electrodeposition is substantially started” until it reaches the vicinity of the side electrode plate 17, and thus is included in the scope of the present invention.

Here, the "distance" between the object and the electrode which is sufficient for "electrodeposition substantially starts" cannot be specified unconditionally, but at least during the transportation of the object, The closest distance between the object and the electrode can be said to be the "distance" in the design of the apparatus. Also in the present invention, if the electrodeposition paint 1 collides with the object to be coated at least until the object to be coated and the electrode come closest to each other, the process is performed "until the electrodeposition is substantially started". Consider

In the present embodiment, the position where the riser 44 and the nozzle 45 are arranged (the place where the electrodeposition paint is discharged toward the object to be coated by the electrodeposition paint discharge means) is located at the tank side end. The part 6 extends from the inlet-side inclined part 7 to the flat bottom part 8 (peripheral part of one longitudinal end of the electrodeposition tank in which the object to be coated enters). In the present invention, it is not limited to such a position, but by arranging at such a position, before the object to be coated reaches the vicinity where the electrode to which electricity is normally supplied is arranged, around the so-called tank entrance. Since the electrodeposition paint can collide with the object to be coated, the arrangement efficiency of each means is good, and it does not affect the energization for electrodeposition coating and hinders continuous production. There is no.

In this embodiment, the position where the riser 44 and the nozzle 45 are arranged (the place where the electrodeposition paint is discharged by the electrodeposition paint discharge means toward the object to be coated) corresponds to the electrodeposition tank 2. In the transport direction of the workpiece 3 (arrows Y _{1 to} Y ₃
Direction) (near the left and right sides in the advancing direction of the object to be coated). In the present invention, it is not always necessary to arrange them on both the left and right sides, and they may be arranged on any one of them, such as on the bottom surface of the electrodeposition tank.
It is preferable to arrange at a position where a streak-like repelling unevenness is particularly problematic in the object to be coated, in order to meet the object of the present invention. Of course, by arranging the electrodeposition paint on the left and right sides, the electrodeposition paint can collide from the left and right sides of the article to be coated in the electrodeposition tank, so that the arrangement efficiency of the electrodeposition paint discharge means is good, It is possible to solve the problem of cissing unevenness in a wide area and / or an appropriate place of the object to be coated.

In the present embodiment, the direction of the discharge port of the nozzle 45 is such that the electrodeposition paint 1 can collide with the workpiece 3 entering the tank substantially perpendicularly. However, the direction of the nozzle can be arbitrarily changed, for example, for the purpose of aiming at a place where the stripe-shaped repelling unevenness is a particular problem in the object to be coated. Needless to say, the direction in which the electrodeposition paint 1 can collide with the coating object 3 entering the tank substantially perpendicularly depends on the disposition efficiency of the nozzles and the pressure and amount of the electrodeposition coating material that collides with the coating object. It is preferable from the viewpoint of sufficiently securing.

The gap between the discharge port of the nozzle 45 and the object immersed in the electrodeposition coating material is not particularly limited, and in the present invention, the electrodeposition coating material is effectively applied to the object 3 in the present invention. There is no problem as long as it is a distance that can make 1 collide. However, if it is too close,
The workpiece 3 or the carrier 13 and the nozzle 45 may interfere with each other. On the other hand, if the workpiece is too far away, the electrodeposition paint of an appropriate pressure and amount cannot collide with the workpiece. The gap is preferably in the range of 20 to 50 cm, more preferably in the range of 20 to 30 cm.

The depth of the riser 44 and the nozzle 45 from the water surface is not particularly limited, and there is no problem as long as the depth allows the electrodeposition paint 1 to effectively collide with the article 3 to be coated. However, if it is too deep,
The electrodeposition paint 1 cannot be made to collide with a large area, and if it is too shallow, a wave is generated on the liquid surface by the liquid flow or the electrodeposition paint 1 scatters around, so that the depth is appropriate. It is preferable that the thickness be in the range of 20 to 50 cm from the liquid level,
More preferably, it is in the range of 0 to 30 cm.

The discharge pressure of the electrodeposition paint 1 from the nozzle 45 is preferably in the range of 0.05 to 0.1 MPa, more preferably in the range of 0.08 to 0.10 MPa. With such a discharge pressure, the electrodeposition paint can be caused to collide with the object to be coated at an appropriate pressure.

As the nozzle 45, a general nozzle such as a pipe nozzle or a V-type nozzle can be used, but in the present invention, it is particularly preferable to use an ejector type nozzle. The ejector-type nozzle has a configuration in which the surrounding electrodeposition paint is wrapped and ejected when ejected, so if the ejector-type nozzle is used, even if the pump capacity is small, a larger amount of the electrodeposition paint can collide, and the ejection efficiency can be improved. Is good.

FIG. 4 is a sectional view showing an example of a schematic configuration of the ejector type nozzle. A nozzle 50, which is an example of an ejector type nozzle, mainly includes an introduction pipe 52 having a circular opening 51 at the tip, a cover 53 installed to cover the tip of the introduction pipe 52, and a holding ring for holding the cover 53. 60 and the introduction pipe 52 and the cover 5 via the connecting body 62.
And a support table 61 for supporting the support table 3.
The clip 59 is fixed to the riser 64 by a clip 59 (not shown). An inclined portion 54 having a gradually decreasing cross-sectional opening diameter is formed in the vicinity of the distal end portion of the introduction pipe 52 toward the circular opening 51, and the electrodeposition coating material introduced from the direction of arrow C toward the circular opening 51 is formed. The configuration is such that the flow path is narrowed.

Inside the cover 53, a flow path is formed having a shape obtained by cutting the introduction pipe 52 halfway, and the diameter of the flow path is larger than that of the introduction pipe 52 as a whole. That is, the flow path inside the cover 53 is firstly constituted by the cylindrical portion 55 and the inclined portion 56, and the inner diameter of the cylindrical portion 55 is larger than the portion other than the inclined portion 54 of the introduction pipe 52, The rate of the gradual decrease is approximately the same as that of the inclined portion 54, and the opening diameter at the end of the inclined portion 56 is larger than that of the circular opening 51. From the end of the inclined portion 56, a flow path communicates with a discharge port 57 provided at the tip of the cover 53 while keeping the opening diameter unchanged. The introduction pipe 52 is
The introduction pipe 52 is positioned so as to be inserted into the cover 53.
The circular opening 51 is provided with a discharge port 57 from the inside of the cover 53.
Is aimed at. The end of the cylindrical portion 55 of the introduction pipe 52 is
Via an O-ring made of an elastic member, it is pressed and fixed around a circular opening provided on the peripheral surface of the riser 64,
The riser 64 and the introduction pipe 52 communicate with each other.

The outer shape of the cover 53 is mainly spherical, and the portion of the discharge port 57 protrudes.
The inner surface of the opening of the holding ring 60 has a curved shape corresponding to the spherical portion of the cover 53, and
The cover 53 is held in a form in which the spherical portions 3 are fitted. Therefore, the cover 53 can be freely moved within a predetermined range as shown by the arrow F, and the direction of the discharge port 57 can be freely adjusted within the predetermined range.

When the electrodeposition paint is introduced from the direction of arrow C by a pump (not shown), the liquid flow is accelerated by the inclined portion 54 and discharged from the circular opening 51 toward the discharge port 57. The electrodeposition paint discharged from the circular opening 51 directly goes to the discharge port 57 and is discharged from the discharge port 57 as a result. At this time, the gap between the cover 53 and the introduction pipe 52 becomes negative pressure, and the bottom of the cover 53 (The end of the cylindrical portion 55), the surrounding electrodeposition paint is taken in as shown by the arrow D. The electrodeposition paint discharged from the circular opening 51 is covered with a cover 53.
Is discharged in the direction of arrow E as a whole as a large amount of electrodeposition paint while entraining the electrodeposition paint taken in from the skirt portion.

It is desirable that the ejector-type nozzle has the above-described configuration, but the ejector-type nozzle is not limited to the above-described configuration as long as the configuration is such that the surrounding electrodeposition paint is rolled and discharged at the time of discharge. More detailed conditions of the ejector type nozzle may be appropriately set according to the object of the present invention, the effect to be achieved, and the like, but it is preferable that the condition satisfy at least the above-described discharge pressure.

The number and pitch of the nozzles 45 in the riser 44 (interval between adjacent nozzles) are desirably such that the electrodeposition coating material 1 can effectively collide with the article 3 to be coated. Of course, the number of nozzles 45 is 1
Any number may be used, but it is preferable to use a plurality of them because the electrodeposition paint 1 can collide with a large area of the object 3, and an appropriate number thereof depends on the size of the object 3, the pitch of the nozzles 45, and the like. The numbers will be different. The pitch of the nozzles 45 is preferably in the range of 10 to 50 cm,
More preferably, it is in the range of ４０40 cm.

[0055] As the length of the riser 44, as can collide the electrodeposition coating 1 in a wide area of the article to be coated 3, viewed from the side of the conveying direction of the article to be coated 3 (arrow Y ₁ direction) It is desirable to set the length over the entire trajectory of the article 3. However, if it is too long, it will interfere with the side electrode plate 17. When the article 3 is a white body of an automobile, the length of the riser 44 is desirably about 1 to 3 m, and more desirably about 1 to 1.5 m.

In this embodiment, the riser 44 is
Although an example is shown in which one piece is arranged on each of the left and right sides in the traveling direction of the article 3 and near the liquid surface, the number of risers may be plural. By providing a plurality of risers above and below, the electrodeposition paint 1 can collide with a wider area of the work 3. In this case, the arrangement of the nozzles connected to the riser may be a checkerboard pattern, a staggered pattern, or a random state.

In this embodiment, the riser 44 is arranged substantially parallel to the liquid surface of the electrodeposition coating material 1, but it does not necessarily have to be substantially parallel to the liquid surface of the electrodeposition coating material 1. For example, it arranged perpendicular to the conveying direction of the article to be coated 3 (arrow Y ₁ direction), may be provided with any other angle.

In the present embodiment, the nozzle 45 is arranged so as to be connected to the riser 44.
You can connect directly from 7 '. In this case, the liquid may be immersed below the liquid level from the opening of the electrodeposition tank 2 using a flexible liquid feeding pipe, or the nozzle 45 may be installed so as to protrude from the wall surface of the electrodeposition tank 2 to the inside. Good.

In the present embodiment, an example in which the nozzle 45 is used as an electrodeposition paint discharging means for discharging the electrodeposition paint toward the object to be coated is described, but the invention is not limited to this. Absent. As the other means, for example, by rotating a screw, the electrodeposition paint 1
It may be moved inside to collide with the article 3 to be coated. However, if the electrodeposition paint is ejected onto the object using the nozzle 45, the electrodeposition paint 1 with a sufficient pressure and amount can be caused to collide with the object 3, and the apparatus configuration is simple. In addition, since it is easy to adjust the discharge direction of the electrodeposition coating material 1, it is possible to solve the cissing unevenness at an appropriate portion of the workpiece 3.

In the present embodiment, there is provided a so-called continuous electrodeposition coating apparatus in which the object to be coated is continuously moved into the electrodeposition tank while being moved by the transporter, and the tank is discharged after the electrodeposition coating. Although described as an example, the present invention may of course be a so-called batch-type electrodeposition coating apparatus in which a conveyed object is dipped into an electrodeposition tank by an elevating device and lifted up.

In the case of a batch type electrodeposition coating apparatus, an electrodeposition paint discharging means such as a nozzle for discharging the electrodeposition paint toward the object to be coated is provided at a position where the electrodeposition paint is discharged toward the object to be coated. A nozzle (e.g., a discharge port) may be installed around the tank portion of the electrodeposition tank, or may be installed inside the electrodeposition tank so that the article to be coated after immersion can be aimed at. In the former case, the electrodeposition paint may collide with the object to be coated when the object is immersed by the elevating device, and after the electrodeposition is completely immersed, the electrodeposition may be performed by energizing. In the latter case, after the object to be coated is completely immersed by the lifting / lowering device, first, the electrodeposition paint is caused to collide with the object to be coated by the electrodeposition paint discharge means, and the discharge of the electrodeposition paint by the electrodeposition paint discharge means is stopped. The electrodeposition may be performed by energizing. In the case of a batch type electrodeposition coating apparatus, the same configuration as that described in the above embodiment can be applied,
The preferred configuration is basically the same.

As described above, the present invention has been described with reference to the embodiments and the modifications. However, the present invention is not limited to the configurations of the above-described embodiments and the modifications. Various changes can be made to these according to knowledge. Further, in the above embodiment, the case where the object to be coated is a white body of an automobile has been described as an example, but the object (object to be coated) to be coated by the electrodeposition coating apparatus of the present invention is, of course, The object to be coated is not limited, and any object having conductivity, such as a building material, a chassis of a home appliance, various metal parts, and the like can be used.

In the present invention, applicable electrodeposition paints are
Any of a cationic electrodeposition coating and an anion electrodeposition coating may be used. In particular, the effect of the present invention is more remarkably exhibited in the case of a cationic electrodeposition coating material in which the problem of streaking due to contamination components brought in from the pretreatment step is likely to occur.

Hereinafter, the properties of a typical cationic electrodeposition coating used in the electrodeposition coating apparatus of the present invention or an example of a method for producing the same will be described. It is needless to say that the composition of the electrodeposition paint or the production method thereof is not limited to this. The cationic electrodeposition paint used in the electrodeposition coating is, in effect, an emulsion that functions as a binder between the object to be coated and the coating film component, or between the coating film component particles,
It is a liquid mixture obtained by mixing a pigment paste that forms the color of the coating film with ion-exchanged water (pure water).

A typical emulsion consists of an aqueous emulsion of an epoxyamine adduct blended with a crosslinking agent, which has been neutralized with an acid to form a water-soluble product.
In such emulsions, a metal catalyst is generally added to the mixture of the epoxyamine adduct and the crosslinker before adding water to form the emulsion. In addition,
The metal catalyst is added in solution and mixed with a mixture of an epoxyamine adduct and a crosslinker (see US Pat. No. 4,419,467).

As the crosslinking agent, as is well known, a chain type or cyclo type aliphatic isocyanate or an aromatic isocyanate, for example, hexamethylene diisocyanate, cyclohexamethylene diisocyanate, toluene diisocyanate, methylene diphenyl diisocyanate, etc. Is used. These isocyanates are blocking agents that block the isocyanate functionality, i.e. the crosslinking functionality, such as oximes,
Prereacted with alcohol and caprolactam. The blocking agent separates upon heating, resulting in reactive isocyanate groups and crosslinking (see U.S. Pat. No. 4,419,467). The epoxyamine adduct and the blocked isocyanate are the main resin components in the electrodeposition paint, and the resin usually contains about 40 to 90% by weight of the epoxyamine adduct and about 60 to 10% by weight of the blocked isocyanate. included.

The pigment paste is prepared by dispersing the pigment in a dispersing vehicle and adding desired additives such as a wetting agent, a surfactant and an antifoaming agent. Here, as a vehicle for dispersing the pigment,
Generally known general ones are used. The particle size of the pigment after dispersion is typically about 6 to 8 on a Hegman grain gauge.

The pigment paste includes a wetting agent, a surfactant,
An additive such as an antifoaming agent can be added. In this case, the additive is preferably added at a ratio of about 0.1 to 2.0% by weight based on the solid binder in the pigment paste. preferable. In addition, as a surfactant or a wetting agent,
Alkyl imidazolines, acetylenic alcohols and the like are used. A plasticizer may be added to the pigment paste. As such a plasticizer, a high-boiling-point water-immiscible material, for example, nonylphenol or bisphenol A ethylene oxide adduct or propylene oxide adduct is used. Such plasticizers are typically used at about 0.1
~ 15% by weight is added.

The electrodeposition paint is an aqueous dispersion. The electrodeposition coating material 1, which is an aqueous dispersion, usually contains about 3 to 50% by weight, preferably 5 to 40% by weight of solid matter. Aqueous dispersions that are further diluted with water when fed to an electrodeposition bath are usually
Contains 10-30% by weight solids.

A solvent for adjusting the film resistance is also added to the electrodeposition paint. Typical membrane resistance adjusting solvents are, for example, hydrocarbons, alcohols, polyols, esters, ethers, ketones, etc., but preferably alcohols, polyols and ketones. Further, as the film resistance adjusting solvent, monobutyl and monohexyl ether of ethylene glycol or phenyl ether of propylene glycol may be used. The addition amount of the film resistance adjusting solvent is generally about 0.1 to 15% by weight based on the weight of the binder solid,
Preferably it is about 0.5-5% by weight.

[0071]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. Pump pressure 2 kg / cm ² , discharge rate 110 liter / mi
n. Was prepared, and a riser having a length of 1.5 m was connected to the outlet side of the pump via a hose. The riser includes five ejector-type nozzles (Spraying Systems Co., Ltd.) at a pitch of 30 cm from the tip.
Made). In this way, a test electrodeposition paint discharging means was prepared. Note that the electrodeposition paint discharging means is 2
I prepared a pair.

The above-mentioned electrodeposition paint discharging means was installed in an electrodeposition tank in an actual automobile body line (RV vehicle painting line). Specifically, the submersible pump was first immersed in the electrodeposition tank on both the left and right sides in the traveling direction of the white body of the automobile. And, on the left and right sides on the entry side of the electrodeposition tank,
The riser was fixed parallel to the liquid level. At this time, the ejector-type nozzle attached to the riser was configured so that the discharge port was directed substantially at right angles to the side surface of the white body of the automobile being conveyed.

At this time, the depth of the ejector nozzle from the surface of the electrodeposition coating liquid was 20 cm. The shortest distance between the discharge port of the ejector type nozzle and the white body of the automobile was 20 cm, and the discharge pressure of the electrodeposition paint from the ejector type nozzle was 0.1 MPa.

Cleaning of pretreatment for zinc phosphate coating treatment
Pretreatment and electrodeposition coating were performed with the degreasing conditions slightly lower than the standard conditions. At this time, the white bodies of 100 vehicles (RV vehicles) were put into the painting line without switching on the submersible pump, and with 100 switches on. After the electrodeposition coating, it was baked and dried, and the appearance of the coating film was visually checked.

As a result, when the submersible pump was turned on without being turned on, clear streak-shaped uneven spots were observed around the rear doors of all 100 units. Slight streak-like unevenness was confirmed in 2 out of 100 vehicles, indicating that the present invention can significantly suppress streak-like unevenness.

[0076]

According to the electrodeposition coating apparatus and the electrodeposition coating method of the present invention, during the electrodeposition coating, the influence of contamination adhering to the object to be coated which could not be sufficiently cleaned and degreased in the pretreatment step. Thus, it is possible to provide an electrodeposition coating apparatus capable of providing a uniform coating film regardless of the type. Further, the electrodeposition coating apparatus of the present invention,
The configuration is simple, and a high effect can be obtained at low cost. In addition, since the characteristic device configuration is simple, the current electrodeposition coating line can be improved to easily suppress problems caused by contamination such as streak-like unevenness on the object to be coated.

[Brief description of the drawings]

FIG. 1 is a top view showing an example of an electrodeposition coating apparatus according to the present invention, in which an external configuration is omitted.

FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, including a transport device.

FIG. 3 is a cross-sectional view taken along line BB in FIG. 1, including a schematic configuration for explaining a circulation state of an electrodeposition liquid and an electric circuit in an electrodeposition coating apparatus in addition to an outline of a transporting apparatus. Things.

FIG. 4 is a cross-sectional view showing an ejector-type nozzle that is preferably applied to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electrodeposition paint 2 electrodeposition tank 3 object to be coated 4 transport mechanism 6 entrance side end 7 entrance side slope 8 flat bottom 9 exit side slope 10 exit side end 11 rail 12 carrier 13 carrier 15 DC power supply DESCRIPTION OF SYMBOLS 16 Minus-side conductor 17 Side electrode plate 18 Bottom electrode plate 19 Plus-side conductor 20 Diaphragm room 21 Diaphragm 22 Diaphragm liquid tank 23 Diaphragm liquid 23 Electrodeposition paint 24 Pump 25 First diaphragm liquid pipe 26 Second diaphragm liquid pipe 27 Pure water tank 28 Pure water 29 Pure water supply passage 30 Conductivity meter 31 Control valve 32 Controller 35 Fluid stirring mechanism 37 Tank 38 Circulation pump 39 Electrodeposition paint circulation pipe 40 Electrodeposition paint discharge means 41 Filter 42 Flow control valve 43 Liquid temperature control device 44 Riser 45 Nozzle 46 Pump 47 Liquid sending pipe 50 Nozzle 51 Circular opening 52 Inlet pipe 53 Cover 54 Oblique portion 55 cylindrical portion 56 inclined section 57 discharge ports SP electrodeposition coating device

Claims (9)

[Claims] 1. An electrodeposition tank containing at least a liquid electrodeposition coating material, a transporting means for allowing an object to be coated to enter the electrodeposition tank, and for discharging the electrodeposition coating after the electrodeposition coating, and the electrodeposition tank The substrate to be coated and immersed in the electrodeposition paint becomes one electrode,
Further, a DC voltage is applied between the object to be coated and the electrode plate so that the electrode plate disposed apart from the object to be coated in the electrodeposition tank becomes the other electrode, and And an energizing means for electrodepositing the coating material on the surface of the object to be coated, further comprising: an electrodeposition coating device, further comprising: And an electrodeposition paint discharging means for discharging the electrodeposition paint toward the object to be coated in the electrodeposition tank before the electrodeposition is substantially started after being immersed in the electrodeposition paint. An electrodeposition coating apparatus characterized in that: 2. The electrodeposition coating apparatus according to claim 1, wherein the electrodeposition tank has a boat shape or a rectangular parallelepiped shape, and the transporting means moves the object to be coated in a longitudinal direction of the electrodeposition tank. A continuous transfer means for entering the tank from one end, proceeding in the longitudinal direction in the electrodeposition tank, and leaving the tank from the other end in the longitudinal direction of the electrodeposition tank; Is a means for applying a DC voltage between the object to be coated and the electrode plate while the object to be coated is progressing in the longitudinal direction in the electrodeposition tank, apparatus. 3. A part where the electrodeposition paint is discharged toward the object by the electrodeposition paint discharge means is a peripheral part of one end where the object to be coated enters the tank in a longitudinal direction of the electrodeposition tank. The electrodeposition coating apparatus according to claim 2, wherein 4. The apparatus according to claim 2, wherein said electrodeposition coating material discharging means discharges said electrodeposition coating material toward said object on both right and left sides in a traveling direction of said object.
Or the electrodeposition coating apparatus according to 3. 5. An electrodeposition paint discharge means comprising: one or more nozzles having discharge ports directed to the object to be coated immersed in the electrodeposition paint; The electrodeposition coating according to any one of claims 1 to 4, comprising a pump for taking in paint and sending the solution to the nozzle, and a solution sending pipe connecting the pump and the nozzle. apparatus. 6. The nozzle according to claim 1, wherein a gap between a discharge port of the nozzle and the object immersed in the electrodeposition paint is 30 to 50 cm.
The electrodeposition coating apparatus according to claim 5, wherein the electrodeposition coating apparatus is disposed in the electrodeposition tank so as to fall within the range of: 7. The electrodeposition tank according to claim 5, wherein the nozzle is arranged in an electrodeposition tank such that a depth from a liquid level of the electrodeposition paint is in a range of 20 to 50 cm. An electrodeposition coating apparatus as described. 8. The electrodeposition coating apparatus according to claim 5, wherein a discharge pressure of the electrodeposition paint from the nozzle is in a range of 0.05 to 0.1 MPa. . 9. The electrodeposition coating apparatus according to claim 5, wherein the nozzle is an ejector type nozzle.