JPH0310096A - Electrodeposition coating device - Google Patents

Abstract

PURPOSE:To adjust the removal efficiency of acid without discharging heavy meals, etc., into the coating material in a bath by providing a second electrode in opposition to a material to be coated as a first electrode and using a diaphragm electrode device as the second electrode. CONSTITUTION:The material 1 to be coated as the first electrode and the second electrode 2 consisting of plural electrodes are opposed in an electrodeposition bath 100, and the diaphragm electrode devices 3 and 4 are used as the second electrode 2. The diaphragm electrode device 3 is provided with a diaphragm for infiltration-extracting a neutralizer in the electrodeposition coating aq. soln. W (cationic coating material) contained in the bath 100. The diaphragm electrode device 4 has a first function to block most of the ion current in the neutralizer in the aq. soln. W to be absorbed by the electrode of the diaphragm electrode device 4 and a second function to block the flow of the ion eluted from the electrode side of the diaphragm electrode device 4. Consequently, the mixing of heavy metal ions into the aq. soln. W due to the elution of the electrode is almost completely prevented, and the removal efficiency of acid can be adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrodeposition coating device, and more specifically, the present invention relates to an electrodeposition coating device.
The object to be coated forming the electrode part and the second object disposed corresponding to the object to be coated
The present invention relates to an electrodeposition coating apparatus including an electrode section, in which a diaphragm electrode device is used as the second electrode section.

[Conventional technology]

Electrodeposition coatings can be roughly divided into those using anionic paints and those using cationic paints, but in both cases, the uniformity and adhesion of the coating to the object are excellent. In addition, since it generates little pollution, it has recently been widely applied, for example, to automatic coating treatment of automobile bodies, as it is particularly suitable for undercoating or L-coat finishing of metal coatings.

Among the paints used in such electrodeposition coatings, the above-mentioned anionic paints include those made water-soluble by attaching carboxyl groups to a resin with a molecular weight of 2,000, and the cationic paints include The paint used is one in which an amino group is attached to the resin component of the paint to make it water-soluble. On the other hand, even these water-soluble paints have a weak degree of ionization after being dissolved in water. For this reason, at present, in the case of anionic paints, an alkaline neutralizer such as triethylamine is mixed in, and in the case of cationic paints, an acidic neutralizer such as acetic acid is mixed in, and these are neutralized and soaked in water. A material designed to increase the degree of ionization is used.

In this way, a neutralizing agent is mixed to increase the degree of ionization depending on the properties of the resin component of each paint, but on the other hand, as the electrodeposition process of the coating progresses, the resin component of the paint in the solution increases. When the amount decreases, the paint must be replenished from the outside, so amine or acetic acid as a neutralizing agent is continuously accumulated in the solution, causing phenomena such as re-dissolution of the painted surface or the formation of pinholes. This results in a situation where the efficiency of electrodeposition coating is significantly impaired.

For this reason, in recent years, for example,
As seen in Publication No. 1, one electrode is separated from the object to be coated and the aqueous solution using an ion exchange membrane or the like, and the ion exchange membrane or the like is used to remove amine or acetic acid from the aqueous solution. So-called pH control, which prevents an increase in the amount of neutralizing agent in the aqueous solution by osmosis and extraction, is being carried out and is being tried to be effective.

Here, cationic electrodeposition using a cationic paint will be explained.

Conventionally, in cationic electrodeposition, anionic crosslinker mff1 has been used as a diaphragm. This anion exchange membrane usually has a value of 8 to 10XIO-h [mol/Liron] as an acid removal electrical efficiency (acid coulomb removal rate).

The acid (neutralizing agent) added to the aqueous solution for electrodeposition (ED bath paint) in the electrodeposition bath layer is only the amount A contained in the paint supplied to the electrodeposition bath layer.

On the other hand, the acids carried out from the ED bath paint include: 10-20% of the A contained in the UF filtrate used as a washing liquid after electrodeposition coating; 2 A carried out contained in the paint film. 5 to 10 [%] of A; (1) 70 to 80 [%] of A removed by the diaphragm electrode;

Ideally, the amount A and the amount B should be equal, but since this is difficult to adjust, generally BAA is often used to replenish the acid that is running low from the outside.

For this reason, if all the electrodes installed in the electrodeposition bath layer are diaphragm electrodes, the removal of acid will be excessive in the electrodeposition layer, resulting in a lack of acid, which is a neutralizing agent. Managing the neutralizing agent in the ED hot bath paint becomes troublesome, as more acid needs to be supplied, and acid is wasted. For this reason, today, acid removal is balanced by configuring the electrodes as so-called bare electrodes without a diaphragm.

As mentioned above, a removal rate of 8 to 10XIO-'' [mol/coulomb] results in excessive acid removal;
” (mol/coulomb) provides an approximately ideal acid removal balance, so a neutral membrane having such an acid removal rate is sometimes used.

In addition, in cation electrodeposition, it is also possible to use a cation exchange membrane as a part of the diaphragm electrode.

[Problem that the invention sought to solve]

However, the above-mentioned conventional technique that partially uses naked electric coating has the following serious disadvantages in meeting the recent demands for high-quality coating finishes.

That is, sludge mainly composed of inorganic pigments deposited on the surface of bare electric scrapers becomes a problem, and among the useful ingredients in the paint, it promotes electrolytic corrosion of the electrodes (usually 5US316 is often used). It often contains components that cause corrosion, and it causes severe electrolytic corrosion when energized. Normally, the electrolytic corrosion rate of 5US316 is about 2~3X10-''C grams/coulomb] with respect to the flowing current, but in the above case, it is about 100~150
X10-''C grams/coulomb).

In this way, heavy metal ions (iron, chromium, nickel, etc.) eluted from the electrodes due to electrolytic corrosion were mixed into the paint, causing problems such as roughening of the painted surface and a decrease in rust prevention ability. .

Further, even in the case of using a neutral membrane in the conventional example described above, the same problem occurred because the neutral membrane allows components such as heavy metal ions that promote electrolytic corrosion to pass through.

Furthermore, when using the above-mentioned conventional cation exchange membrane, the coulomb removal efficiency of acid is very low at less than 1 x 10-'' (gram/coulomb), and the cation exchange membrane is used in a part of the entire diaphragm. Although excessive removal of acid can be prevented by using a
It can even reach gram/ri, -ron]. In other words, this means that if a cation exchange membrane is used, most of the heavy metal ions eluted from the electrodes will be mixed into the paint.

[Object of the Invention] The object of the present invention is to improve the disadvantages of the conventional examples and, in particular, to provide an electrodeposition coating device that can adjust the acid removal efficiency without releasing heavy metals etc. into the bath paint. Our goal is to provide the following.

[Means to solve the problem]

Therefore, in the present invention, an object to be coated as a first electrode section disposed in an electrodeposition bath and a second electrode section consisting of a plurality of electrodes arranged corresponding to the object to be coated are provided. and electrodepositing the film-forming substance on the object to be coated by passing an electric current through an aqueous solution of the film-forming substance contained in the electrodeposition bath between the object to be coated and the second electrode part. It looks like this. Here, a diaphragm electrode device having a diaphragm portion that separates each electrode from the aqueous solution is used as each electrode constituting the second electrode portion, and some of the diaphragm electrode devices are While blocking most of the flow of ions in the neutralizing agent in the aqueous solution attracted to the electrode,
It has a diaphragm portion that is absorbed by the first electrode and blocks the flow of ions flowing out from the electrode side of the diaphragm electrode device, and the remaining diaphragm electrodes have diaphragm portions that permeate and extract the neutralizing agent. It has this configuration. This is an attempt to achieve the above-mentioned purpose.

[For production]

A case where the electrodeposition coating apparatus of the present invention is used for cationic electrodeposition coating will be explained.

First, when applying a DC voltage with the object to be coated as a negative electrode and each diaphragm electrode device constituting the second electrode part as a positive electrode,
Electrode coating starts immediately as usual, and the positively charged paint resin components and pigment colloid molecules in the aqueous electrodeposition coating solution move toward the negative electrode object and adhere to the surface of the object. After discharge, the solids of the paint aggregate to form a paint film.

On the other hand, acetic acid having a negative charge is accumulated in the aqueous solution, and this acetic acid starts moving toward the electrodes of each diaphragm electrode device at the same time as the above-mentioned electrodeposition coating starts. For example, when a composite exchange membrane consisting of a cation exchange membrane on the paint side and an anion exchange membrane on the electrode side is used as the diaphragm part of some diaphragm electrode devices, the cation exchange membrane is Since it is located on the paint side, the flow of acid, which is a neutralizing agent in the aqueous solution, is mostly blocked by this cation exchange membrane and cannot reach the electrode side, and the acid accumulates in the aqueous electrodeposition solution. However, since this cation exchange membrane does not completely block acetic acid, a portion of it reaches the electrode and is discharged. On the other hand, the action of the anion exchange membrane effectively prevents the heavy metal ions eluted from the electrode from flowing out to the electrodeposition aqueous solution side.

On the other hand, since the remaining diaphragm electrode device is equipped with an anion membrane that allows negatively charged acetic acid molecules to easily pass through, the acid molecules attracted to the electrode of the diaphragm electrode device at a positive potential are
The electrons easily pass through the anion exchange membrane along the lines of electron force, reach the electrodes, and are discharged. In this case, similarly to the above, the action of the anion exchange membrane effectively prevents the heavy metal ions eluted from the electrode from flowing out to the electrodeposition aqueous solution side.

[First Embodiment] Hereinafter, a first embodiment of the present invention will be described based on FIGS. 1 to 4.

This example shows a case where the present invention is applied to a cationic electrodeposition coating apparatus using a cationic paint.

The embodiment shown in FIG. 1 consists of an object 1 to be coated as a first electrode section disposed in an electrodeposition bath 100 and a plurality of electrodes arranged corresponding to the object 1 to be coated. A second electrode part 2 is provided. As each electrode constituting this second electrode section 2, a diaphragm electrode device 3.3. . . . and diaphragm electrode device 4, 4. ... is used.

As the diaphragm electrode device 3, one equipped with a diaphragm portion for permeating and extracting the neutralizing agent in the aqueous solution for electrodeposition coating (aqueous solution of cationic paint) W contained in the electrodeposition bath 100 is used. . The diaphragm electrode device 4 also has a first function of blocking most of the flow of ions in the neutralizing agent in the aqueous solution W attracted to the electrodes of the diaphragm electrode device 4, and The diaphragm electrode device 4 is equipped with a diaphragm portion having a second function of blocking the flow of ions eluted from the electrode side of the diaphragm electrode device 4.

To explain this in more detail, the diaphragm electrode device 4 includes a main body part 11 and an electrode part 12, as shown in FIG.

A water passage mechanism 14 is provided between the two.

The main body portion 11 includes first and second insulating tubes 15 and 16 coaxially arranged at a predetermined interval, and a relatively hard diaphragm support member 1 that connects each of these insulating tubes 15 and 16.
7, a diaphragm portion 9 wrapped around the outer periphery of the diaphragm support member 17, and an outer cloth 18 further wrapped around the outer surface of the diaphragm portion 9.
It is composed of. The outer cloth 18 is made of, for example, chemical fiber, and is sufficiently durable against tension and has water permeability.

The diaphragm support member 17 is formed into a relatively long tube shape using a non-conductive net member or a water-permeable porous member, and supports the first and second insulating tubes 15 and 16 on the inner diameter side of both ends thereof. Arranged to connect.

Further, as shown in FIG. 3, the diaphragm portions 9 are each formed in a cylindrical shape, and have a cation exchange membrane 7 disposed on the outside (on the paint side) and a cation exchange membrane 7 facing the cation exchange membrane 7. Anion exchange membrane 8 disposed on the inner electrode section 12 side
It is composed of a double-structured ion exchange membrane consisting of. External cation exchange M! 7 and the inner anion exchange membrane 8 are wound around the outer periphery of the diaphragm support member 17 with both ends integrally fixed to each other, as will be described later. In reality, the surfaces of the cation exchange membrane 7 and the inner anion exchange membrane 8 have some unevenness, so that a certain gap is formed between the opposing portions of the two. For this reason, small holes 8 are formed at the upper and lower ends of the inner anion exchange membrane 8 as shown in FIG.
a, 8b are provided, and these small holes 8a, 8b are provided respectively.
The polar liquid always fills the gap between the cation exchange membrane 7 and the anion exchange membrane 8 via the membrane 7, thereby preventing the generation of voids that would impede current flow.

The reason why the diaphragm portion 9 has a double structure is that the cation exchange membrane 7 is placed on the paint side to prevent the flow of acid (negative ions), which is a neutralizing agent, in the aqueous solution W (ED bath paint). , most of the cation exchange membrane 7 is blocked, and an anion exchange membrane 8 is disposed on the inside near the electrode 30 side, and the positive (+) heavy metal ions eluted from the electrode 30 are blocked by the anion exchange membrane 8. This is to prevent it. In other words, the acid permeability of the cation exchange membrane is less than lXl0- & [mol/coulomb], which is 8 to 10xlO- when an anion exchange membrane is used.
(mol/coulomb)], and the permeation amount of heavy metals under normal electrodeposition coating line operating conditions is 4 to 15 mol/coulomb when using a cation exchange membrane.
X10-'' (gram/coulomb), whereas in the case of anion exchange membrane, it is 0.025xlO-''C gram/coulomb.
This is because it has an extremely low value (Coulomb).

Here, if the acid, that is, the negative (=) ions are blocked by the cation exchange membrane 7, and the positive ions are blocked by the anion exchange membrane 8, it is thought that no current will flow, but for the following reasons, in reality sufficient current flows.

A portion of the water at the interface between the cation exchange membrane 7 and the anion exchange membrane 8 is ionized into [H゛] and (OH-). In the case of neutral purity, the degree of ionization is (H”), (OH
-) are both about 10-' (mol/liter),
At the interface between the anion exchange membrane 8 and the cation exchange membrane 7, the degree of ionization is uneven. That is, as shown in FIG. 4, on the surface of the anion exchange membrane 8, the anion exchange group (-
Due to the presence of NH゛) etc., the concentration of (O)(-) is high,
Conversely, on the surface of the cation exchange membrane 7, cation exchange groups (-s
O, "-3, etc. exist, so the concentration of [H゛] is high.

Both (OH-) and (H.) have extremely high ion transfer rates, which causes charge transfer.

Further, since the diaphragm portion 9 is wound around the diaphragm support member 17, its mechanical strength against external pressure is significantly increased. Furthermore, the outer cloth 18 is spirally wrapped around the entire outer circumferential surface of the diaphragm portion 9 as described above, thereby adding sufficient pressure resistance against internal pressure. .

As shown in FIG. 2, first and second frames 20 and 21 are disposed at a predetermined interval on the outer periphery of both ends of the diaphragm support member 17 around which the diaphragm portion 9 and the outer cloth 18 are wound. established,
At the same time, potting material 4 is placed on the inner diameter side of this frame 20.21.
1, thereby each of the insulating tubes 15, 16
and the diaphragm support member 17 and the diaphragm portion 9. It has a structure in which the outer cloth 18 is simultaneously and firmly integrated. In this case, the first frame 20 is formed into a cylindrical shape, and when filling the botting material 41, a ring member 22 is installed to prevent the botting material 41 before solidification from flowing out. It is disposed within the first frame 20.

The second frame 21 is formed into a cylindrical shape with a bottom, and the diaphragm support member 17 and the insulating tube 16 are inserted into the second frame 21 as described above (filled with potting material 41, The entire structure is fixed together at the same time.

Although epoxy resin is used as the potting material 41 in this embodiment, it may also be urethane resin, phenol resin, or the like.

In this embodiment, hard vinyl chloride pipes are used as the first and second insulating pipes 15 and 16. Among them, the first insulating pipe 5 has a drainage section 13 as shown in FIG.
is provided, and a cap 24 is removably attached to its upper end.

Reference numeral 15A indicates a spacer fixed to the inner diameter side of the upper end of the insulating tube 15.

On the other hand, the electrode section 12 includes a tubular electrode 30 made of stainless steel and formed into a tubular shape, and a metal lid member 3 for locking the electrode hanging, which is attached to the upper end of the tubular electrode 30 in FIG.
1 and a power supply connection terminal 32 provided on this lid member 31
and a water supply section 33. Among these, the tubular electrode 30 is formed so that its outer diameter is smaller than the inner diameter of each of the first and second insulating tubes 15 and 16 of the main body portion 11 described above. Therefore, the tubular electrode 30 can be easily attached to and removed from the main body 11, and at the same time, a part of the water passage mechanism 14 is formed between the main body 11 and the tubular electrode 30. . Further, the outer peripheral edge of the metal lid member 31 protrudes from the tubular electrode 30, so that the tubular electrode 30 is locked by the first insulating tube 15 as shown in FIG. It looks like this. Therefore, the electrode section 12 can be inserted into the main body section 11 with great ease from the outside, and can be easily removed to the outside by scratching if necessary.

The water passage mechanism 14 is for discharging acetic acid and the like accumulated between the diaphragm section 9 and the tubular electrode 30 to the outside, and is specifically composed of the electrode section 12 and the main body section 11 described above. ing. That is, the water flowing from the water supply part 33 of the electrode part 12 flows down inside the tubular electrode 30, as shown by the arrow in FIG. 5, and flows from below to the outer circumferential side of the tubular electrode 30. At the same time, it flows inside the diaphragm part 9 while rising on the outer peripheral side of the tubular electrode 30, and flows into the discharge part 13 together with impurities.
It is now forcibly leaked from the outside.

A mounting fitting 11A for mounting on a bathtub during electrocoating is wrapped around one frame 20 portion of the main body 11. Further, the outer cloth 18 wrapped around the outer surface of the diaphragm portion 9 is
It is not necessarily limited to a cloth-like member, and may be replaced with another member as long as it has the same reinforcing function and water permeability. Furthermore, each of the ion exchange membranes constituting the diaphragm portion 9 may be wound spirally or may be formed into circular slices, provided that the joint portion is waterproof.

Here, the method of fixing the diaphragm portion 9, which constitutes the main portion of the main body portion 11 mentioned above, will be described in more detail.

First, the anion exchange membrane 8 constituting the diaphragm portion 9 is wound around the outer periphery of the diaphragm support member 17, and the abutting edges of the anion exchange membrane 8 are brought into contact with each other so that the anion exchange membrane 8 has a substantially circular cross section as shown in FIG. Stick to shape. The cation exchange membrane 7 is wound on top of this, and the abutting ends are overlapped or abutted against each other, and are fixed in a substantially circular cross-section as shown in FIG. Next, the outer cloth 18 is spirally wound around the outer surface of the cation exchange membrane 7, thereby completing the integration of the diaphragm support member 17 and the diaphragm portion 9.

Next, the first and second insulating tubes 15 and 16 described above are fitted to both ends of the cylindrical diaphragm member thus formed as shown in FIG. On the outside, the first and second frames 20.21 are arranged at a predetermined interval as described above. And each frame 20.2
1 is filled with potting material 41 and solidified, thereby completing the integration of the main body portion 11.

It should be noted that the sealing member 22 disposed inside the lower end of the first frame 20 in FIG. After the botting material 41 is solidified, it may be removed.

The diaphragm electrode device 3 has substantially the same structure as the diaphragm electrode device 4, but a normal anion exchange membrane is used in place of the diaphragm portion 9. The other configurations are the same as the diaphragm electrode device 4 described above.

Next, the overall operation of this embodiment will be explained.

First, the object to be coated 1 was used as a negative electrode, and the diaphragm electrode device 3.3
．． ...and 4.4. When a DC voltage is applied using each of the tubular electrodes 30 as the positive electrode, electrode coating starts immediately as usual, and the colloidal molecules of the paint resin component and pigment, which have positive charges in the aqueous solution, are coated on the negative electrode. After moving towards object 1, adhering to the surface of the object to be coated and discharging,
The solids of the paint aggregate to form a paint film.

On the other hand, negatively charged acetic acid is accumulated in the aqueous solution, and this acetic acid is absorbed into the diaphragm electrode devices 3, 3..., 4. 4.
. . . starts moving toward each tubular electrode 30. Here, since each diaphragm electrode device 3 uses an anion membrane that allows negatively charged acetic acid molecules to easily pass through, the acetic acid molecules attracted to the tubular electrode of the diaphragm electrode device 3 at a positive potential are It easily passes through the anion exchange membrane along the lines of force, reaches the tubular electrode 30 from around the tubular electrode 30, and is discharged. In this case, since almost all of the discharged neutralizer is ionized at low concentrations, it is attracted to the anode during energization and is therefore accumulated between the tubular electrode 30 and the anion exchange membrane. By the way, since pure water, for example, is forced to flow between the tubular electrode 30 and the anion film as described above, the accumulated acetic acid is continuously discharged to the outside together with the pure water.

On the other hand, in each diaphragm electrode device 4, since the cation exchange membrane 7 is located on the paint side, most of the flow of acetic acid, which is a neutralizing agent in the aqueous solution W, is blocked by the cation exchange membrane 7 and the cation exchange membrane 7 is located on the paint side.
The 0 side cannot be reached, and acetic acid accumulates in the aqueous solution W for electrodeposition. However, since this cation exchange membrane 7 does not completely block acetic acid, a portion of it reaches the electrode 30 and is discharged. In the same manner as described above, acetic acid is accumulated between the tubular electrode 30 and the diaphragm portion 9, and the accumulated acetic acid is continuously discharged to the outside together with pure water. On the other hand, the action of the anion exchange membrane 8 effectively prevents the heavy metal ions eluted from the electrode 30 from flowing out to the electrodeposition aqueous solution W side.

The inventor actually measured the acid removal rate and heavy metal permeability of a diaphragm electrode device in which the diaphragm part 9 had a double structure of a cation exchange membrane 7 and an anion exchange membrane 8, and found that: ■ Acid removal rate 1.3X10 A heavy metal permeability of 0.058XlO-b (gram/coulomb) was obtained.

(This value is somewhat inferior to the individual characteristic values of each diaphragm mentioned above, but this is because, as mentioned above, in the cation exchange membrane 7, cations moving from the polar liquid side are transferred to the anion membrane 8. There is a shortage of charges and carriers passing through the cation exchange membrane 7, and the anion (acid) tends to carry the charge through the passage of the anion (acid). (This is because the acid is blocked by the cation exchange membrane 7 and carriers of anions are depleted, so that the anions tend to carry charge by passing through.) However, the cation exchange membrane 7 By creating a double structure in which the and anion exchange membrane 8 are superimposed,
The acid removal rate can be reduced to about 1/7 of that when using a normal anion exchange membrane alone, and the permeation of heavy metals is 0.058X, about 1/70 of that when a cation exchange membrane is used alone.
It was possible to suppress it to 10-h (grams/coulomb).

As explained above, according to the first embodiment, the diaphragm electrode device 4 can suppress the acid removal rate and prevent the outflow of heavy metal ions due to electrode elution, and the anionic membrane can effectively remove acids. Since it uses a diaphragm electrode device 3 equipped with
It has the advantage that it can almost completely prevent heavy metal ions from being mixed into the ED bath paint due to electrode elution. It also has the advantage that the acid removal rate can be set to a desired value by appropriately combining the diaphragm scraping device 3 and the diaphragm electrode device 4.

(Second example) Next, a second embodiment will be explained based on FIG. 6.

Here, the same reference numerals are used for the same components as in the first embodiment described above.

As shown in FIG. 6, an object 1 to be coated as a first electrode portion is disposed in the center of an electrodeposition bath 100.

Further, in the electrodeposition bath 100, tubular electrodes 30 constituting the second electrode section 2 are arranged at both ends thereof, corresponding to the object 1 to be coated.

Further, between these tubular electrodes 30 and the object 1 to be coated, there is a diaphragm portion 9 for separating each tubular electrode 30 from the aqueous solution W of the cationic paint contained in the electrodeposition bath 100 and the object 1 to be coated. is equipped with.

To explain this in more detail, the diaphragm portion 9 consists of a cationic paint 7 disposed on the side of the object 1 to be coated and an anion exchange membrane 8 disposed on the tubular electrode 30 side opposite to the cation exchange membrane 7.
It is composed of.

Since these cation exchange membranes 7, 7 and 8 have low strength, they are actually equipped with a diaphragm support member formed of a non-conductive mesh member or a water-permeable porous member (not shown). . Further, the anion exchange membrane 8 disposed on the tubular electrode 30 side is provided with small holes at its upper and lower ends, respectively.

Although these small holes are not shown here, they are actually provided at several locations. Therefore, the polar liquid always fills the space between the cation exchange membrane 4 and the anion exchange membrane 5 through these small holes, so that no gap is generated that would impede current flow.

Further, on the side of the object l of the diaphragm portion 9, diaphragm electrode devices 3, 3. It is equipped with...

Even in this case, the same effects as those of the first embodiment described above can be obtained.

[Third example] Next, a third embodiment will be described based on FIG. 7.

In this embodiment, the diaphragm electrode device 3.3 in the first embodiment described above is used. . . . and the object 1 to be coated. The other configurations are the same as those of the first embodiment described above.

Even with this configuration, the same operation and effect as in the first embodiment can be obtained, and the voltage applied between each diaphragm electrode device 3 and the object to be coated 1 can be adjusted by the operation of the voltage adjustment means 40. This has the advantage that the amount of acid in the electrodeposition bath 100 can be easily adjusted.

In addition, in the first to third embodiments described above, the diaphragm portion 9
Although the case where the double structure of the cation exchange membrane 7 and the anion exchange membrane 8 is illustrated as an example, the diaphragm section 19 shown in FIG. 8 may be used instead of the diaphragm section 9. A diaphragm portion 29 shown in the figure may also be used. As shown in FIG. 8, the diaphragm portion 19 includes a base material 26 made of nylon or polyethylene woven fabric, a cation exchange resin 27A on one surface 26a (the surface facing the ED bath paint), and a cation exchange resin 27A on the other surface (the surface facing the electrode). It is a composite exchange membrane formed by coating each side surface (26b) with an anion exchange resin 27B. In addition, the diaphragm part 2
9, as shown in FIG. 9, anion exchange resin 27B and cation exchange resin 27A are mixed at a ratio of 50:50, and a mixture obtained by binding with a binder 27C is used as a base material made of nylon or polyethylene woven fabric. This is a composite exchange membrane formed by coating both sides of 26. Microscopically, by mixing both types of exchange resins, this has the same effect as a diaphragm system with multiple layers of cation resin/anion resin/cation resin/anion resin/... It is something that has. In addition, a practical effect in terms of acid removal rate was confirmed even when the mixing ratio was between 10:90 and 90:10.

(Effects of the Invention) Since the present invention is configured and functions as described above, it is possible to almost completely prevent heavy metal ions from being mixed into the paint component (ED bath paint) in the electrodeposition aqueous solution due to electrode elution. It is possible to provide an unprecedented and excellent electrodeposition coating apparatus that can prevent acid removal and adjust the acid removal efficiency.

[Brief explanation of drawings]

FIG. 1 (1) is an explanatory diagram showing the arrangement of each diaphragm electrode device as seen from above in the first embodiment of the present invention, FIG. 1 (2) is an explanatory diagram showing the configuration of the first embodiment of the present invention, Figure 2 is the first
3 is a sectional view taken along the line III-III in FIG. 2, and FIG. FIG. 5 is an explanatory diagram showing the flow path of water in the device of FIG. 2. FIG. 6 is an explanatory diagram showing the configuration of the second embodiment of the present invention. FIG. 7 is an explanatory diagram showing the configuration of a third embodiment of the present invention, and FIGS. 8 and 9 are explanatory diagrams showing modifications of the first to third embodiments. ■...Object to be coated as first electrode, 2...
... second electrode, 3 ... some diaphragm electrode devices,
4... Remaining diaphragm electrode device for permeating and extracting the neutralizing agent, 100... Electrodeposition bath, W... Cationic paint as an aqueous solution of coating film forming substance. Aqueous solution.

Claims (2)

[Claims] (1), comprising an object to be coated as a first electrode section disposed in an electrodeposition bath and a second electrode section consisting of a plurality of electrodes arranged corresponding to the object to be coated, Electrodeposition of the coating film-forming substance onto the coating material by passing an electric current through an aqueous solution of the coating film-forming substance contained in the electrocoating bath between the coating material and the second electrode part. In the coating apparatus, a diaphragm electrode device having a diaphragm portion for separating each electrode from the aqueous solution is used as each electrode constituting the second electrode, and some of the diaphragm electrode devices are A first function of blocking most of the flow of ions in the neutralizing agent in the aqueous solution attracted to the electrode of the electrode device, and a second function of blocking the flow of ions flowing out from the electrode side of the diaphragm electrode device. What is claimed is: 1. An electrodeposition coating apparatus, comprising: a diaphragm section having a function of a diaphragm section, and a diaphragm section through which the remaining diaphragm electrode device permeates and extracts the neutralizing agent. (2) At least one of the diaphragm electrode devices equipped with a diaphragm portion for permeating and extracting the neutralizing agent is equipped with voltage adjustment means for adjusting the voltage applied to the electrodes of the diaphragm electrode device. The electrodeposition coating apparatus according to claim 1.