JP3150209B2 - Washing method of electrodeposition coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to electrodeposition coating, UF washing,
The present invention relates to a method for washing an electrodeposition coating film after industrial water washing.

[0002]

2. Description of the Related Art In electrodeposition coating, after electrodeposition in an electrodeposition tank, UF is applied.
(Ultra Filtration System) A UF rinsing step using a liquid obtained by extracting water from the electrodeposition paint using an apparatus, an industrial water rinsing step using industrial water, and a final pure water rinsing step are required.

[0003] The UF rinsing step aims to eliminate paint loss by washing and recovering paint adhered to the surface of the object to be coated. The industrial water rinsing step aims to improve the finish by washing with higher washing efficiency.

The purpose of pure water washing is to improve the performance by washing the contaminant ions attached to the surface of the object to be coated.

[0005] In terms of process, the UF rinsing system uses a combination of spraying and immersion rinsing to perform two to three stages of water washing, and industrial water washing also performs two to three stages of water washing similarly to UF water washing, and pure water washing. Is one stage.

[0006]

[0008] After the pure water rinsing, after the baking in the baking furnace, it is possible to prevent a finish defect (secondary sagging, unevenness in the washing, etc.) caused by insufficient drainage of the washing water. To do this, a standing time of about 10 minutes is required. However, when this step is adopted, the length of the whole step becomes large, and therefore, the whole apparatus becomes large, the installation area is required to be large, and there is a problem that the equipment is complicated and the equipment cost is high. In addition, there is a problem that running costs are increased due to an increase in the amount of industrial water and pure water used, and costs during wastewater treatment are increased.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, to reduce the length of a washing step after an electrodeposition coating process, and to provide a method for washing an electrodeposition coating which can be easily performed.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a method for washing an electrodeposited article by baking the electrodeposited article before baking is performed. Washing is performed by spraying the cleaning liquid and immersing the UF cleaning liquid after the spraying, and recovering the electrodeposition coating material from the UF cleaning liquid obtained by the cleaning, immersing the UF-cleaned coating object in industrial water, and The substrate is rinsed with a spray of industrial water after immersion in the industrial water, and the substrate to be rinsed is hung from a position above the substrate in a state of being hung on a hanger 19a by spraying a diluent with a nozzle 11a. , This diluent is a nonionic surfactant,
At least one of an anionic surfactant and a cationic surfactant has a concentration of 0.005 to 1 in pure water.
This is a method for washing electrodeposited coating water characterized by containing 0%.

[0009]

Function: After electrodeposition coating, UF rinsing, industrial water rinsing, and in the electrodeposition coating rinsing method for removing impurities physically attached to the electrodeposition coating film, a nonionic interface is applied to pure water used for rinsing. At least one of a surfactant, an anionic surfactant and a cationic surfactant is used in an amount of 0.005 to 0.005;
Contains 1.0%. The higher the concentration of the surfactant added to the pure water, the better, but the effect starts to appear at 0.005%.
Also, 1.0% has a sufficient effect, and even if added more, the effect is hardly changed, and there is a demerit due to an increase in the use amount due to a high concentration and an increase in wastewater treatment cost. As a result, drainage is good with an optimal amount of the surfactant used, leaving no time for leaving after washing with water, and the time required for the process can be shortened. In particular, according to the present invention, the electrodeposited coated object is washed with a UF cleaning liquid by spraying with nozzles 3 and 4 and then immersing in immersion tank 5 to collect the electrodeposition coating material. Washing is performed by immersing the immersion tank 7 with industrial water and spraying with a nozzle 9, and then washing by spraying with a nozzle 11 using a diluting liquid. The spray of the diluting liquid suspends the object to be coated on a hanger 19 a. In the lowered state, the object is washed with water from a position above the object to be coated, so that the sagging from the hanger 19a is reliably prevented. The diluent has a concentration of 0.005 to 1.0 in pure water.
% Of nonionic, anionic and cationic surfactants, so that drainage is good and the working time can be shortened.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a view for explaining a step of washing a substrate 19 with a diluent containing a surfactant, and FIG. 2 is a view for explaining all steps of an electrodeposition coating process. . As shown in FIG. 2, an object to be coated is an electrodeposition tank 1 filled with an electrodeposition paint 2.
After the electrodeposition treatment, the UF is washed with a UF cleaning liquid sprayed from the nozzle 3 in the UF first water washing step. Then, after being further washed with a UF washing liquid sprayed from the nozzle 4 in the UF second washing step, it is immersed in the immersion tank 5 filled with the UF washing liquid 6 in the UF third washing step. In the UF first to third rinsing steps, the electrodeposition paint is recovered from the UF cleaning liquid obtained by the cleaning.

Next, in a first industrial water washing step, the substrate is immersed in an immersion tank 7 filled with industrial water 8 and then washed with industrial water sprayed from a nozzle 9 in a second industrial water washing step. In the third water washing process, the water is washed with industrial water sprayed from the nozzle 10.

After that, a diluting liquid containing a surfactant is sprayed from a nozzle 11 realized by a spray gun or the like, washed with water, and after draining, baking is performed in a baking furnace 12.

The spraying of the liquid containing a surfactant using the nozzle 11 is performed by the apparatus shown in FIG.
The surfactant is sent from the tank 13 storing the undiluted solution of the surfactant to the quantitative dilution tank 15 by the metering pump 14. At the same time, the pure water electromagnetic valve 16 is opened and water is injected up to the upper limit of the float switch 17.

An agitator 18 is provided in the dilution tank 15, and the above-described surfactant and pure water are agitated by the agitator 18 to produce a diluent.

The object 19 to be hung by the hanger 19a
Is detected by the photoelectric switch 20, the electromagnetic valve 21 is opened, the pump 22 is operated, and the diluting liquid is sprayed on the object 19 by the nozzle 11 realized by a spray gun or the like, and washed with water. Since the substrate 19 is washed with a diluent of a surfactant, the substrate 19 is quickly drained.

FIG. 3 is a diagram showing the relationship between the position of the nozzle 11 and the object to be coated. FIG. 3 shows a nozzle 11 a capable of spraying a diluting liquid from a position above the object 19 and a spray 11 b located on a lower side surface of the object 19.

Improvement of finish of horizontal part, hanger 19a
In the case of sagging prevention and blister prevention,
The nozzle 11a which sprays the diluting liquid from the upper position is used. When the purpose is to prevent the secondary dripping of the joint, the diluting liquid is sprayed from the position of the nozzle 11b located on the lower side surface of the object 19 Is preferred.

FIG. 4 is a graph showing the relationship between the concentration of the surfactant and the result of the secondary sagging test. FIG. 4A shows the result when the immersion treatment is performed, and FIG. 4B shows the result when the spray washing is performed.

The preparation of the test piece for performing the secondary sagging test is as follows:
First, the electrodeposition coating is performed, and after the electrodeposition coating, the test piece is washed with water at a flow rate of 1 L / min for 10 seconds, and then, when performing the immersion treatment, immersed in a dilute solution having a predetermined concentration for 10 seconds, and spray-washed. In this case, after performing spray cleaning at a flow rate of 1 L / min for 10 seconds, a baking treatment is performed after leaving each of them for 1 minute.

In this embodiment, nonionic emulgens # 909 and # 910 were used as surfactants. Surfactants are classified into anionic, nonionic and cationic. When used for electrodeposition washing, any surfactant may be used, but in consideration of the effect of residual ions, it is most preferable to use a nonionic surfactant.

In the judgment of the result of the secondary sagging test, “○” is good, “◇” is a slight sagging of the secondary sagging on the actual line, but need not be modified, and “△” is a minor sagging. Indicates a defect in which secondary sagging is required, and "x" indicates a defect.

In the case of using only water, secondary sagging due to a failure in washing occurred in both immersion washing and spray washing. When the concentration of the surfactant is 0.005%,
In the case of the immersion treatment with good water washing efficiency, “○” was good, but in the case of spray water washing with poor water washing efficiency, the result of “◇” was obtained, and the effect was not sufficient. When the concentration of the surfactant was 1.0%, the effects of both the immersion treatment and the spray water washing were recognized, and favorable "O" was obtained in each of the test results. It is considered that the reason why the secondary sagging test result becomes better as the concentration of the surfactant increases is that the surface tension of water decreases as the concentration of the surfactant increases, and the drainage property is improved.

When the concentration of the surfactant was 2.0%, as good as 1.0%, good results were obtained. However, if the concentration is high, there are economic disadvantages such as an increase in the treatment amount and a decrease in the wastewater treatment property.
It is suitably from 0.5 to 1.0%.

As described above, according to this embodiment, the surface tension of the water can be reduced and the drainage property can be improved by rinsing with water containing a surfactant at the time of rinsing before the baking treatment. Therefore, the standing time after the water treatment can be reduced, the size of the electrodeposition coating apparatus can be reduced, and the water washing treatment can be easily performed.

[0025]

As described above, in the electrodeposition coating water washing method for removing impurities physically attached to the electrodeposition coating film after the electrodeposition coating, pure water used for water washing contains a nonionic surfactant,
It contains 0.005 to 1.0% of at least one of an anionic surfactant and a cationic surfactant. For this reason, the drainage is good and the standing time after the washing is not required, and the time required for the process can be shortened. Therefore, the size of the electrodeposition coating apparatus can be reduced, and the configuration can be simplified. In particular, according to the present invention, the substrate to be washed after being sprayed with industrial water is hung on the hanger 19a, and the diluting liquid is sprayed from the position above the substrate by the nozzle 11a, and thus the hanger 19a. Is prevented, and the finish of the object to be coated is improved. Further, according to the present invention, the electrodeposited substrate is first washed with a UF cleaning solution, then with industrial water, and finally with pure water having a concentration of 0.005 to 1.
The cleaning is performed by spraying a diluting liquid to which 0% of a surfactant is added, and thus the object to be coated before baking is surely cleaned. Furthermore, in the present invention, in cleaning the UF cleaning liquid, immersion is performed after spraying, and in cleaning of industrial water, immersion is performed first, and then spraying is performed for cleaning, and thus the electrodeposition paint is cleaned. In a state where the concentration is very low, a diluted solution of pure water containing a surfactant is sprayed, and thus the finish of the object to be coated before baking is improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating water washing with a diluent of the present invention.

FIG. 2 is a diagram illustrating an electrodeposition coating process of the present invention.

FIG. 3 is a diagram illustrating a position of a nozzle 11 during a water washing process.

FIG. 4 is a graph showing the relationship between the concentration of a surfactant and the result of a secondary sagging test.

[Explanation of symbols]

 13 Tank 14 Metering Pump 15 Dilution Tank 16 Electromagnetic Valve 17 Float Switch 18 Stirrer 19 Coating Material 20 Photoelectric Switch 21 Electromagnetic Valve 22 Pump

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Nobuo Kuranami 6-10-73 Minamitsukaguchi-cho, Amagasaki City, Hyogo Prefecture Inside Shinto Paint Co., Ltd. (56) References JP-A-52-155645 (JP, A) JP-B-47-51450 (JP, B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) C25D 13/00

Claims (1)

(57) [Claims] 1. A method for rinsing an electrodeposited coated object with water before baking is performed, wherein the electrodeposited coated object is sprayed with a UF cleaning liquid and after spraying. Of the UF cleaning solution obtained by the cleaning, the electrodeposition paint is collected from the UF cleaning solution, and the UF-cleaned object is immersed in industrial water, and the industrial water after immersion in the industrial water. The object to be washed is hung on a hanger 19a and washed with water by a nozzle 11a from above the object to be sprayed with a diluting liquid. A concentration of at least one of a surfactant, an anionic surfactant and a cationic surfactant in pure water of 0.005 to 1.0%. Washing method.