JP3154568B2 - Washing method of electrodeposition coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a UF (Ultra Filtratio)
n System) The present invention relates to a water washing method for electrodeposition coating that is further performed after the water washing step.

[0002]

2. Description of the Related Art In electrodeposition coating, when an object to be electrodeposited in an electrodeposition tank is lifted out of the electrodeposition tank, the paint physically adhered to the surface of the electrodeposited coating film is removed. Take it out of the tank. The rinsing step is composed of a UF rinsing step for the purpose of collecting paint and an industrial rinsing step using industrial water for the purpose of improving the finish quality. In the process water washing process, two or three-stage water washing is generally performed by a combination of spray water washing and immersion water washing depending on the finish quality and shape.

[0003] Industrial water (work water) supplied to the rinsing after the UF rinsing step is usually used at room temperature.

[0004]

The washing efficiency of the electrodeposited coated surface is affected by the washing water concentration, temperature and spray pressure. In order to reduce the concentration of impurities adhering to the surface to be coated, it is necessary to increase the amount of water supply, but this has the problem of increasing the cost.

[0005] Although increasing the spray pressure has the effect of lowering the concentration of impurities adhering to the surface to be coated, the spray pressure is unlikely to hit the inner plate portion and the bag structure portion of the object to be coated, and the inner plate portion and the bag structure do not. There is a problem that the washing efficiency is reduced in the part.

In addition, the temperature of the washing water is conventionally at room temperature, which causes a problem that the washing efficiency is reduced. Further, since there is a difference in the water temperature between summer and winter, there is a difference in the washing efficiency. However, there is a problem that the quality varies.

An object of the present invention is to provide an electrodeposition coating for solving the above-mentioned problems and stabilizing the quality, and a method for washing after UF washing.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a method for washing an electrodeposited article with water prior to a baking step, wherein the electrodeposited article is washed with UF water. After removing the electrodeposition paint physically attached to the coating film and recovering the electrodeposition paint, the electrodeposition paint was immersed in industrial water 4 in the immersion tank 3 and washed by this immersion. 1 tank 14
The industrial water supplied by the first pump 16 is sprayed from the first nozzle 18 for cleaning, and then the industrial water supplied by the second pump 20 from the second tank 19 is sprayed from the second nozzle 22. Washing, supplying industrial water to the second tank 19, supplying the industrial water overflowing from the second tank 19 to the first dunk 14 from the pipe 23,
The industrial water in the first tank 14 is supplied to the immersion tank 3 by the third pump 15, drained from the drain pipe 5 provided at the bottom of the immersion tank 3 by the fourth pump 7, and heated by the heat exchanger 6. And returned to the immersion tank 3 and circulated. The temperature of the industrial water in the immersion tank 3 was maintained at 30 to 45 ° C, and the temperature of the industrial water sprayed from the first and second sprays 18 and 22 was 45 to 60 ° C. This is a method for washing electrodeposited coating water, characterized in that:

[0009]

[0010]

According to the present invention, the object to be coated is transported by the transporting means into the electrodeposition tank containing the electrodeposition paint, the electrodeposition coating is performed, the UF water washing for collecting the paint is performed, and then the coating is performed. In the electrodeposition coating washing method for washing impurities on the surface of the object with water, 30 ° C.
Water of 45 ° C. is used for washing in the immersion tank 3. The higher the temperature of the washing water is, the higher the effect is. However, a good result is obtained at 30 ° C. or more. At 45 ° C. or higher, there is not much difference in the effect, and running costs are required to raise and maintain the temperature. If the temperature used for water washing is 30 ° C. to 45 ° C. in the immersion tank 3 and 45 ° C. to 60 ° C. in the first and second sprays 18 and 22, unnecessary costs for maintaining the temperature are not added.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a view for explaining a water washing step using industrial water. The electrodeposited object 1 is a UF (Ultra F
iltration System) In the water washing process, the electrodeposition paint physically adhered to the coating film is removed, and the electrodeposition paint is collected. After that, in the water washing process using industrial water shown in FIG. The removal of the impurities is performed.

The substrate 1 after the UF rinsing is conveyed by a conveyor 2 and first immersed in industrial water 4 in an immersion tank 3. A drain pipe 5 is provided at the bottom of the immersion tank 3, and the drain pipe 5 is connected to the bottom of the immersion tank 3 again via the heat exchanger 6 and the pump 7. The industrial water 4 is circulated between the drain pipe 5 and the immersion tank 3 via the heat exchanger 6 by the pump 7.

The heat exchanger 6 is provided with a pipe 8 for passing hot water or steam. A three-way valve 9 is provided on the inlet side of the pipe 8, and the inlet side and the outlet side of the pipe 8 are directly connected by a bypass passage 10 provided in the three-way valve 9.

A thermometer 11 is provided in the immersion tank 3, and the temperature obtained by the thermometer 11 is used as a temperature detector 12.
After that, the output is output to the three-way valve control unit 13 connected to the three-way valve 9. When the input temperature from the temperature detector 12 is lower than the temperature predetermined for the industrial water 4 in the immersion tank 3, the three-way valve controller 13 allows hot water or steam to pass through the heat exchanger 6 to reach an appropriate temperature. For example, the three-way valve 9 is switched so that the bypass passage 10 passes.

The industrial water 4 is supplied from the first tank 14 via a pump 15. After water washing by immersion is performed, the object to be coated 1 is subjected to spray cleaning. The article 1 is further conveyed by the conveyor 2 and washed with the first tank 14 and industrial water sprayed from a plurality of nozzles 18 connected via a pump 16 and a pipe 17. Further, the article 1 to be coated is
And industrial water sprayed from a plurality of nozzles 22 connected via a pump 20 and a pipe line 21, and are again washed with spray water, and then conveyed to the subsequent baking step.

The second tank 19 is supplied with industrial water. The second tank 19 and the first tank 14 are connected by a pipe 23, and the industrial water overflowing from the second tank 19 is supplied to the first tank 14. Industrial water sprayed from the nozzles 18 and 22 is discharged.

FIG. 2 is a graph showing the relationship between the water temperature and the result of the secondary sagging test. FIG. 2A shows the result when immersion water washing and cleaning are performed, and FIG. 2B shows the result when spray water washing is performed.

The test piece for the secondary sagging test was subjected to electrodeposition coating, followed by rinsing for 10 seconds at 1 L / min, immersion for 10 seconds in immersion rinsing, and 1 liter for spray rinsing.
After washing for 10 seconds under the condition of / min, the substrate is left at room temperature for 1 minute, and then baked at 175 ° C for 20 minutes. "○" is good, "◇" is secondary dripping that does not need to be corrected even if it occurs on the actual line, "△" is light secondary debris is light but requires correction, and "x" is defective Indicates a defect.

As shown in FIG. 2, the evaluation is getting better as the temperature of the water to be cleaned rises. This is because although the coating electrodeposited on the surface of the substrate 1 is insoluble in water, the impurities remaining after removing the physically adhered electrodeposition coating are water-soluble, This is because the dissolving power is improved as the value becomes higher.

As shown in FIG. 2 (1), the immersion water washing, in which water easily enters the joints of the iron plate and the bag structure, tends to be better as the temperature of the washing water rises, and is almost good at 30 ° C. As a result, “◇” is obtained. At 45 ° C., good “」 ”was obtained, and the same was true at 60 ° C.

As shown in FIG. 2 (2), in the spray water washing, a favorable result of “○” is obtained at 45 ° C. 4 at 60 ° C
Good "O" results similar to 5 ° C are obtained. However, 6
If the temperature exceeds 0 ° C., there is a problem that the electrodeposited coating film dissolves, causing a problem of uneven washing with water. In both immersion washing and spray washing, running costs for raising the temperature of the washing water and maintaining the temperature are required, which is an economical disadvantage. For this reason, the temperature of the washing water is controlled by the immersion tank 3.
Then, 30 ° C to 45 ° C is preferable.

As described above, according to the present embodiment, the temperature of the washing water at the time of washing is set to 30 to 45 ° C. in the immersion tank 3 so that impurities adhering to the surface of the article 1 can be removed. The washing effect is improved, and the quality of electrodeposition coating can be easily improved.

As shown in FIG. 1, in this embodiment, the immersion tank 3 is provided with a heat exchanger 6, and the temperature of the industrial water 4 in the immersion tank 3 is increased. Is set at 45-60 ° C. The configuration of the heat exchanger 6 shown in FIG. 1 is not limited to this.

[0024]

As described above, according to the present invention, the temperature of the water used for rinsing is maintained at 30 to 45 ° C.
By setting the temperature of the second sprays 18 and 22 to 45 to 60 ° C., the efficiency of washing impurities adhering to the surface of the object to be coated is improved, and the surface of the object to be coated can be washed without causing uneven water washing. It can be easily performed, and the quality of electrodeposition coating can be easily improved. First, the industrial water is supplied to the second tank 19.
And the overflowed industrial water is supplied from the pipe portion 23 to the first tank 14, and the industrial water in the first tank 14 is supplied to the immersion tank 3 as described above.
And the temperature of the second sprays 18 and 22 is 45 to 60 ° C., and the lower temperature is 30 to 45 ° C. in the immersion tank 3.
By sequentially lowering the temperature in the immersion tank 3 than in the steps 8 and 22, the cost of maintaining the temperature can be further reduced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a washing step using industrial water according to the present invention.

FIG. 2 is a graph showing a relationship between cleaning water temperature and evaluation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Coated object 3 Immersion tank 4 Industrial water 6 Heat exchanger

──────────────────────────────────────────────────続 き Continuation of the front page (72) Nobuo Kuranami 6-10-73 Minamitsukaguchicho, Amagasaki City, Hyogo Prefecture Inside Shinto Paint Co., Ltd. (56) References JP-A-4-346696 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C25D 13/00

Claims (1)

(57) [Claims] 1. A method for washing an electrodeposited object by rinsing the electrodeposited object with water before the baking step, wherein the electrodeposited object is washed with UF water and physically coated on the coating film. After removing the electrodeposition paint adhered to the substrate and collecting the electrodeposition paint, the electrodeposition paint was immersed in industrial water 4 in the immersion tank 3, washed with water by this immersion, and then removed from the first tank 14 to the first pump 16. The industrial water supplied by the first nozzle 18 is sprayed and washed, and the industrial water supplied by the second pump 20 from the second tank 19 is sprayed and washed from the second nozzle 22. The industrial water is supplied to the second tank 19, the industrial water overflowed in the second tank 19 is supplied to the first dunk 14 from the pipe 23, and the industrial water in the first tank 14 is immersed in the immersion tank by the third pump 15. 3 and provided at the bottom of the immersion tank 3. Drained from the drainage line 5 drained by the fourth pump 7, heated by the heat exchanger 6, returned to the immersion tank 3 and circulated, keeping the temperature of the industrial water in the immersion tank 3 at 30 to 45 ° C. A method for washing electrodeposited coating water, wherein the temperature of industrial water sprayed from the first and second sprays 18 and 22 is maintained at 45 to 60 ° C.