JPS58207395A - Formation of paint film - Google Patents

Abstract

PURPOSE:To ensure high electric conductivity and to improve the finish of a paint film, by bringing a coating jig made of an electrically conductive square bar and having cationic paint films formed by electrodeposition into contact with a stripping soln. to strip the films off. CONSTITUTION:Cationic paint is electrodeposited on the surface of a material to be coated by using a coating jig 13 made of an electrically conductive square bar. At the same time, paint films 48 are formed on the jig 13. The jig 13 is brought into contact with a stripping soln., and the films 48 swollen with the soln. are stripped off by jetting water on the films 48. The cleaned jig 13 is used again in electrodeposition coating.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of forming a coating film by electrodeposition, and in particular to a method of performing electrodeposition coating while completely peeling off the coating film adhering to a jig, using a Kanaon type electrodeposition paint. It is something.

Electrodeposition coating is used as a primer coating for metal parts for vehicles. Conventional electrodeposition coatings used anionic paints, but paints with poor rust prevention effects have become mainstream, and the paint films formed by this have excellent adhesion to metal parts, and the paint itself has Because the crosslinks are thin, it exhibits an excellent rust prevention effect, but on the other hand, there is a problem in that a coating film is formed on the painting jig such as a hanger used when painting the other side, making it difficult to remove4. It is difficult to dissolve with the alkaline solution used to remove the electrocoated coating film of the nion type, which is applied with electricity using a hanger1.For this reason, stripping agents based on organic acids such as formic acid and organic solvents such as menalene chloride are used. However, it is not possible to remove it completely, and there are problems such as it obstructs the conduction of electricity during the painting process, or it gradually peels off and disperses in the paint, worsening the finish of the product. was there.

This invention was made by focusing on the above-mentioned conventional problems, and uses a painting jig made of square lumber, and after bringing the jig with the coating film into contact with a stripping solution, water is sprayed onto the jig. The object of the present invention is to provide a method for forming a coating film that can efficiently perform the entire electrodeposition coating process by peeling off the coating film.

This invention relates to a method of performing electrodeposition coating using a cationic electrodeposition paint to form a coating film on the surface of an object to be coated.
Electrodeposition is performed using a conductive square material coating jig, and the jig with the coating film is brought into contact with a stripping solution, and then water is sprayed to completely remove the coating, and the coating is removed. This is a coating film forming method characterized by subjecting the jig from which the gold has been removed to electrodeposition coating again.

The present invention will be explained below based on the drawings. FIG. 1 is a system diagram showing a coating line in one embodiment of the present invention. In the drawing, 1 is an endless chain conveyor, to which a hanger as a painting jig is attached at a certain bit as described later, and it moves in the directions of arrows A and B, and conveys objects to be painted in the direction of arrow C. The equipment is brought in and the painted items are taken out in the direction of the arrow. In the direction of movement, a pretreatment tank 2, a draining/drying chamber 6, an electrodeposition tank 4, a rinsing tank 5, a baking drying chamber 6, a peeling tank 7, and a peeling rinsing tank 8 are installed. In the line, a hanger with the object to be painted is carried in the direction of arrow C and attached to a chain conveyor 1, and first in a pretreatment tank 2, it is degreased with an alkali or the like, and then treated with a chemical conversion coating using a scolding lead phosphate or the like. Pre-treatments such as these are carried out, and a total of 1 coat of paint is applied to the draining and drying chamber 6.
Electrodeposition is performed by connecting the (-) pole of the object to be coated and the paint to the (T) pole, and a coating film is formed on the surface of the object. After washing away excess paint in the washing tank 5, baking drying is performed in the baking drying chamber 6 at about 180 to 210° C. for about 30 minutes, and the coated product is taken out in the direction indicated by the arrow. On the other hand, the paint film adhering to the hanger from which the painted object has been removed is immersed in a stripping solution in a stripping tank 7, and the deposited coating film is then peeled off and removed by a water jet in the next stripping and rinsing tank 8.

FIG. 2 is a vertical sectional view showing a stripping device according to an embodiment of the present invention, FIG. 3 is a plan view of its dipping tank, FIG. 4 is a sectional view taken along line IV-IV, and FIG. 1, the same reference numerals as in FIG. 1 indicate the same or corresponding parts, and the peeling rinsing tank 8 consists of a first rinsing tank 9, a second rinsing tank 10, and a sixth rinsing tank 11.

The chain conveyor 1 passes through the stripping tank 7 and the first stripping tank in the directions of arrows E and F.
It passes through the washing tank 9, the second washing tank 10, and the third washing tank 11 in this order, and the hanger 1 is attached to a plurality of hooks 12.
3 is installed.

The stripping tank 7 is provided with a dipping tank 14 at the bottom, in which a stripping liquid 715 is stored, and the hanger 16 is moved in an immersed state, and a jacket 16 is formed on the inclined side wall and bottom wall of the stripping tank 7. At the liquid level of the immersion tank 14, a closed liquid level 19 is formed by the partition wall 18, leaving 17 passages for the hanger 16. A layer of flow and rough-in 21 is formed on the surface of the stripping solution 15, which is filled with a regular hexagonal hollow floating body 20 made of high-quality synthetic resin.

Water tanks 22, 23, and 24 are provided at the bottoms of the first washing tank 9, the second washing tank 10, and the third washing tank 11, respectively. Hanger 13 is installed in 1, the first washing tank 9, the second washing tank 10 and the sixth washing tank 11, which flow down to 26 and 22 and are drained from the water tank 22 by a drain pipe 27.
A riser pipe 28, 29, 60 with a large number of nozzles arranged in a row so as to spray all the cleaning water from both sides stands up across the passage, and the riser pipe 28 is connected to the water tank 22 through 31 pumps. However, the riser pipe 29 is connected to the water tank 23 through the pumps 62 and 66, and the riser pipe 60 is connected to the water supply. There is a wire mesh/2 between the ricer pipe 28 and the water tank 22.
A filter 64 consisting of a socket is provided, and screens 65, 66, .
67 are provided. A layer of antifoaming agent 690 is formed on the surface of the cleaning water 38 in the water tank 22 .

Fig. 6 is a partial perspective view showing the installation state of the holder, Fig. 7 is a partially enlarged front view thereof, and Fig. 8 is its Vllll-
FIG. 9 is a perspective view showing a part of the hanger. ... through hook 12;

It is attached to cross hooks 40 provided at predetermined intervals on the chain conveyor 1. The cross hook 40 has a structure that allows the hanger 16 to be rotated by 90 degrees. The hanger 16 is entirely made of stainless steel and has a hook-shaped mounting portion 42 that is suspended from the U-shaped bent portion 41 of the hook 12, and a hanging portion that extends downward from the mounting portion 42. 46, a frame portion 44 connected to this hanging portion 46, a bridge portion 45 connecting this frame portion 44, and a work holding portion 46 fixed to this bridge portion 45.

To form a coating film, the object to be coated is suspended from the workpiece holding portion 46 of the holder 16 and moved to the electrodeposition tank 4, and a canon-type electrodeposition coating is performed. As a result, a coating film is formed on the surface of the object to be coated. At the same time, a coating film is formed on the surface of the hanger 13, but when the bunker 13 is made of square timber,
The coating film formed on the corners becomes thinner, making it easier to peel off. Furthermore, if the hanger 16 is made of stainless steel, a coating film will be less likely to be formed and it will also be easier to peel off.

As the stripping liquid 15, a liquid containing an organic acid, an organic solvent, and a surfactant is used. As the organic acid, formic acid, oxalic acid, etc. can be used, and formic acid is particularly preferred. In addition, organic solvents that have the property of swelling or dissolving the coating film, such as methylene chloride, trichloroethylene, trichloropropane, dichloropropane, etc., can be used, but in particular, methychloride moisturizing agents, antioxidants, etc. can be used as adjuvants. may be added. The blending ratio of the organic acid is 5 to 50% by weight (preferably 10 to 40% by weight)1. The blending ratio of organic solvent is 60~
90% by weight (preferably 65-85% by weight), and the blending ratio of surfactant is 41-10% by weight (preferably 2-7% by weight). When liquid paraffin 21 is added to this stripping liquid, the liquid paraffin 21 forms a layer on the upper surface of the stripping liquid 15.

The antifoaming agent 69 forms a layer on the cleaning water 38, and the stripping liquid 1
Any surfactant can be used as long as it can suppress the foaming of the surfactant added in step 5. For example, a metallurgical quencher (T:1 agent dissolved in kerosene, kerosene, petroleum solvent, clay oil, etc.) may be used. I can do it.

(attached to chain conveyor 1) and Ngar 13,
A coating film is formed by electrodeposition in the electrodeposition tank 4, and is baked in the baking drying chamber 6 to harden and adhere to the film.The hanger 16 enters the peeling tank 7 while suspended from the chain conveyor 1, and is soaked in water. It is immersed in stripping liquid 15 in tank 14 . Here, the coating film swells due to the action of the stripping liquid 15, but the surface tension of the stripping liquid 15 decreases due to the addition of a surfactant.
The stripping liquid 15 penetrates into the gap between the hanger 16 and the paint film, and therefore...
5 penetrates from the outside and the inside, so that the coating film softens and swells in a short period of time.

Figure 10 fat is a horizontal cross-sectional view showing a part of the hanger on which the paint film is formed, tb+ is a square cross-sectional view, (cl is a cross-sectional view taken along the line X-X in the case of a round timber, and Figure 11 (al is a swollen paint film). A horizontal sectional view showing a part of the hanger, fbl is a square lumber,
fcl is a cross-sectional view taken along line XI-XI in the case of a round material, and as shown in FIG. However, by coming into contact with the stripping liquid 15, the coating film 48 swells as shown in FIG. 11 and becomes floating. At this time, the paint film 48 swells regardless of whether the hanger 16 is made of square or round wood, but in the case of square wood, the i+ paint is difficult to cure on the corners 49 and forms a thin film, so it peels off due to this partial force. It is easily penetrated by liquid, and swells and floats faster than round wood. Even when the hanger 13 is made of stainless steel, the paint film does not easily adhere to it, so swelling and floating easily occur, and it is also affected by the stripping solution.

Less corrosion. The immersion time required for swelling is 1 to 10 minutes, preferably 2 to 5 minutes.

Constant temperature water is flowed through the jacket 16, and the stripping liquid 15 is maintained at a temperature suitable for stripping, for example, 15 to 25°C. The layer of flow/ξ rough-in 21 formed on the upper surface of the stripping liquid 15 prevents the stripping liquid 15 in the immersion tank 14 from evaporating, and also prevents the immersion layer 1 from evaporating.
Covering the coating film 48 surface of the hanger 16 pulled up from 4,
Prevents evaporation of solvent, etc. The hollow floating body 20 floating on the open chain liquid surface 19 completely covers the entire liquid surface and prevents the stripping liquid 15 from evaporating. Further, the partition wall 18 has the function of a partition and a guide.

The hanger 13 pulled up from the dipping tank 14 is coated with liquid paraffin to prevent evaporation of the solvent, etc., and sent in a swollen state to the peeling and washing tank 8, where the coating film 48 is peeled off. In the stripping washing tank 8, riser pipes 28-. 60
Water is jetted toward the hanger 16 from a number of nozzles provided in the hanger 16 to peel off the swollen coating film 48. This stripping operation is performed in the first and second washing tanks 9 and IO by riser pipes 28 and 29 provided in two stages, respectively, and in the third washing tank 11, washing is finally performed with tap water. be exposed.

Most of the coating film 48 is peeled off in the first washing tank 9, but the peeled coating film is captured by the filter 34, and the washing water flows down to the water tank 22. At this time, due to the surfactant contained in the stripping liquid 15, S9. Foaming occurs, but since the antifoaming agent 39 is stored on the liquid surface of the water tank 22, its antifoaming action prevents foaming. When the washing water flows down, the layer of antifoaming agent 39 is disturbed and becomes dispersed, but since the antifoaming agent 39 is concentrated in the upper part, the antifoaming effect is performed. Further, since the tip of the drain pipe 27 is below the liquid level, the amount of defoamer 69 discharged is small.

The paint film 48 of the hanger 16 is peeled off while passing through the peeling and washing tank 8, and it is finally washed with water and carried out in the direction of arrow F, and is again subjected to the force in the direction of arrow C in FIG. Then, it is moved to the coating process and subjected to electrodeposition coating.

When the paint film 48 is peeled off in the peeling water washing tank 8, if the hanger 13 is made of square wood, the paint film 48 on the corner portion 49
Because the coating is thin, when water is sprayed on it, the coating film 48
When the material breaks, a peeling force F occurs, and peeling is performed in a shorter time than with round materials. be able to. Even when the hanger 13 is made of stainless steel, the coating film 48 is difficult to adhere to and is therefore easily peeled off. 'Furthermore, if the hanger 13 attaching part 42 is also made of square wood, the contact surface with the bent part 4-1 of the hook 12 will be larger than in the case of round wood, so even if the hanger 13 is exposed to washing water, the hanger 1
The shaking motion of 3 will be reduced. If the hanger 16 swings, the water will not hit in the predetermined direction and the expected effect will not be obtained, but this does not happen in the case of square timber.

In the above explanation, only the conductive part or the mounting part of the hanger 131:r may be made of square wood, but the peeling effect of the coating is better when both parts are made of square wood, and it is easier to manufacture if the entire hanger 131:r is made of square wood. is easy. Also, a pre-treatment tank 2, a draining and drying room 6, an electrodeposition tank 4, a washing tank 5, a baking drying room 6, and a peeling tank 7.
The structure, operating method, etc. of the peeling and washing tank 8 can be changed as appropriate. Furthermore, the present invention is applicable not only to the undercoat coating of metal members for vehicles, but also to the coating of other objects to be coated.

As described above, according to the present invention, a coating jig made of square wood is used, and after the jig with a coating film is brought into contact with a stripping solution, water is sprayed to remove the coating film. As a result, the coating film swells and peels from the corners of the jig, allowing efficient force and complete peeling of the coating film. For this reason, when the jig is supplied to the painting process, there is no obstruction of current flow due to the paint film, and the finish of the newly formed paint film on the object to be painted will not be deteriorated due to peeling of the paint film. is obtained.

If the attachment part of the cleaning agent is made of square timber, it is possible to prevent shaking when washing water is sprayed, and the peeling effect can be further increased.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing a painting line in one embodiment of the present invention, Fig. 2 is a vertical sectional view showing a peeling head in one embodiment, Fig. 6 is a plan view of the dipping tank, and Fig. 4 is a Part I
V-IV sectional view, FIG. 5 is an enlarged sectional view of part 7 in FIG. 2, and FIG. 6 is a partial perspective view showing the installation state of the
Figure 7 is a partially enlarged front view, and Figure 8 is its MII-■
I sectional view, Fig. 9 is a perspective view showing a part of the hanger, Fig. 10 - fat is a horizontal sectional view showing a part of the hanger on which the coating film is formed, fbl is a square lumber, fcl is Figure 11 is a horizontal sectional view showing part of the hanger with swollen paint film, (bl is for square timber,
fcl is a cross-sectional view taken along the line XI-XI in the case of a round material. In each figure, the same numbers indicate the same or equivalent parts, 1 is a conveyor, 2 is a pretreatment tank, 6 is a draining drying chamber, 4 is an electrodeposition tank, 5 is a washing tank, and 6 is a baking dryer. chamber, 7 is a peeling tank, 8
is the peeling washing tank, 9.10.11 is the 1.2.3 washing tank,
12 is a hook, 16 is a hanger, 14 is a dipping tank, 22.
23.24 is a water tank, 28.29.60 is a riser pipe. Agent Patent Attorney Sei Yanagihara Figure 8 Figure 7 W [-1 Figure 10 ((1) (b) (C) d

Claims (1)

[Claims] Electrodeposition IG using i11 cation type single electrodeposition paint
In the method of forming a paint film on the human blood of the object to be painted, a coating agent made of conductive square wood is used to apply the entire coating, and then completely remove the coating layer on which the paint film has been formed. , 1 [After contacting with the paint, spray water to peel off the coating! 41CL, when the jig from which the coating film has been peeled is subjected to electrodeposition coating again, the coating film type IJQ method characterized by ijl! 7. Scope of requirements The coating film forming method described in item 1 (Q of 31" where the attachment part of the jig to the conveyor is
Claim 1 consisting of Q material and (-1th 2π1
The coating film forming method (υ悸'tun1) according to any one of claims 1 to 6, wherein the raw square material is made of stainless steel;
PJ formation method