JPH07268690A - Washing device for electrodeposition coating treated material - Google Patents

Abstract

PURPOSE:To improve the recovering efficiency of a electrodeposition coating material and cleaning work by supplying a liquid mixture of a filtrate separated from the coating material in an electrodeposition vessel with a pure water to a spray unit in a recovering vessel of a final step as a washing water. CONSTITUTION:The electrodeposition coating material 11 in the electrodeposition vessel 10 is introduced into a filter 23 and is separated into a revered coating material and the filtrate, the recovered coating material is returned to the electrodeposition vessel 10 and simultaneously the filtrate is supplied through a pipe line 26, into which the pure water is supplied, to the spray unit 21-3 as the liquid mixture. An electrodeposition coated work is successively washed with the washing water sprayed from the spray units (21-1)-(21-3) and the major part of the used washing water is respectively recovered in the corresponding recovering vessels (22-1)-(22-3). The washing water over flowed from the 3rd recovering vessel 22-3 placed in the final step flows into the 2nd recovering vessel 22-2 and in the same way, the washing water flows from the vessel 22-2 into the vessel 22-1 and from the vessel 22-1 into a sub-tank 10a of the electrodeposition vessel 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for washing an electrodeposition-coated article with water.

[0002]

2. Description of the Related Art Electrodeposition paint stored in an electrodeposition tank is about 20
% Is the solid component of the paint, and the remaining about 80% is water.

Therefore, in a device for washing the electrodeposition-coated paint-treated product with water, the paint in the electrodeposition tank is separated into a recovered paint and a filtrate by a filtering means such as a UF filter (ultra filter), and the filtrate is washed with water. In addition to using it as water, the used filtrate is returned to the electrodeposition tank. The paint collected by the filtering means is returned to the electrodeposition tank.

As is clear from the above description, the water washing device constitutes a so-called recovery water washing system.

[0005]

The paint recovery efficiency of the conventional water washing apparatus is about 90 to 96% at the maximum, but in order to further reduce the burden of waste water treatment of the pure water washing means arranged in the subsequent process. Further, in order to further improve the yield of the paint and the quality of the coating film, it is desired to further improve the recovery efficiency of the paint.

In view of the above situation, an object of the present invention is to provide a water washing device for electrodeposition-coated products which can further improve the efficiency of paint recovery as compared with a working device.

[0007]

According to the present invention, a filtering means for introducing an electrodeposition coating material in an electrodeposition tank to separate it into a recovered coating material and a filtrate, and a plurality of stages arranged behind the electrodeposition tank are provided. A plurality of spray units for spraying cleaning water onto the electrodeposited coating product in the landing tank, and a cleaning liquid sprayed from each of the spray units. A plurality of recovery tanks for recovering the water, the filtrate is used as the cleaning water, and the cleaning water overflowing from the recovery tank excluding the first-stage recovery tank is positioned immediately before the recovery tank. In the water washing device for the electrodeposition coating treated product, the washing water overflowing from the frontmost collecting tank is made to flow into the electrodeposition tank. Mix pure water for replenishment, and mix the mixture at the final stage. Wherein it provided for the tank spray -
The unit is provided with a means for supplying as cleaning water, and the cleaning liquid in the recovery tanks other than the last-stage recovery tank is supplied to the spray units provided corresponding to these recovery tanks.

[0008]

The pure water for replenishment is mixed with the filtrate separated by the filtering means, and the mixed solution is sprayed from the spray unit provided in the cleaning tank at the last stage. Therefore, the electrocoating-treated product is washed with rinsing water having a small content of the coating solid content, and as a result, the electrodeposition coating material recovery efficiency is improved.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an electrodeposition coating facility to which the water washing apparatus of the present invention is applied. In the figure, a body of an automobile (not shown), which is an object to be coated, is dipped in the electrodeposition coating material 11 in the electrodeposition tank 10 and applied with electrodeposition coating. The painted body, which is the coating-treated product, is carried into the water washing device 20 according to the present invention, spray-washed, then dip-washed in the washing tank 30, and further sprayed from the spray unit 40. The recovered water and the pure water sprayed from the spray unit 41 are sequentially washed. It should be noted that the painted body that has undergone the above washing process
Is conveyed to a printing process which is a post process.

The above-mentioned water washing device 20 has spray units 21-1, 21-2 arranged in multiple stages behind the electrodeposition tank 10.
And 21-3, and the primary recovery tank 22-1, the secondary recovery tank 22-2, and the tertiary recovery tank 2 arranged corresponding to these.
2-3 and the UF filter 23.

The spray unit 21-1 includes a pump 2
The cleaning water in the primary recovery tank 22-1 is supplied via 4-1 and the pump 24 is similarly supplied to the spray unit 21-2.
-2, the cleaning water in the secondary recovery tank 22-2 is supplied.

The UF filter 23 introduces the electrodeposition coating material 11 in the electrodeposition tank 10 via the pump 25 and separates the coating material into a recovered coating material and a filtrate. Then, the recovered paint is applied to the electrodeposition tank 1
While returning to 0, the filtrate is supplied to the spray unit 21-3 through the pipe line 26.

A predetermined amount of pure water is also supplied to the pipe line 26 through a valve 27, so that the spray unit 22 is also supplied.
A mixed solution of the above filtrate and pure water is supplied to -3.

A painted body (hereinafter referred to as a work) carried into the water washing device 20 is a spray unit 21.
-1 to 21-3 are sequentially washed with the washing water, and at that time, most of the washing water sprayed from each spray unit corresponds to the corresponding recovery tank 22-.
Recovered from 1 to 22-3.

Then, as shown by the dotted line, the wash water that overflows from the tertiary recovery tank 22-3 located at the last stage is transferred to the secondary recovery tank 22-2 and from the tank 22-2. -The cleaning water to be buffed is the primary recovery tank 22 located at the front stage-
1, and the cleaning water overflowing from the tank 22-1 flows into the sub tank 10a of the electrodeposition tank 10, respectively. Therefore, the recovered water washing system constituted by the water washing device 20 can be represented as a flow chart of FIG.

On the other hand, in the above-mentioned conventional water washing apparatus, as shown by the chain double-dashed line in FIG. 1, the filtrate obtained by the filter 23 is caused to flow into the tertiary recovery tank 22-3 and the inside of the tank 22-3. The cleaning liquid is supplied to the spray unit 21-3, and therefore the flow chart of the recovered water washing system is as shown in FIG.

In the washing system shown in FIG. 2, pure water is added to the filtrate, but in the washing system of FIG. 3, the electrodeposition tank 10 is used.
This pure water is added to. The pure water is replenishment water for compensating for water evaporation in the electrodeposition tank, water evaporation during spraying, water consumption due to work carried out by the work, etc. It is necessary to set the amount W so that the proportion is maintained at a predetermined value (about 20% described above). The electrodeposition paint also needs replenishment, but this replenishment paint is directly added to the electrodeposition tank 10 in any of the water washing systems shown in FIGS.

Here, the following common conditions are set for the recovered water washing systems shown in FIGS. 2 and 3, and the paint recovery efficiency of these water washing systems will be considered.

(Conditions) a. Proportion of paint solids in electrodeposition paint (F): 20% b. Proportion of paint solids in the filtrate (G) ...... 0.5% c. Amount of filtrate (Q): 1200 l / Hr d. Work treatment area per unit time in each step of the recovery water washing system (production amount): 1500 m ² / Hr e. Liquid carry-out amount per unit area of work: 0.2 l / m ² f. Electrodeposition membrane pressure ...... 25μt. Specific gravity of electrodeposited film ...... 1.4 H. Water content of electrodeposited wet film …… 60% Percentage of solid content of paint replenished in electrodeposition tank ...... 50% Evaporation amount in the electrodeposition process: 75 l / hr

In the conventional water washing system shown in FIG. 3, the amount Q of the filtrate from the tanks 22-1 to 22-3 becomes the amount Q of the filtrate, so that the following equation for the recovery water washing equilibrium is established. .

[Recovery primary] F (%) × x (l / Hr) + B (%) × Q (l / Hr) = A (%) × x (l / Hr) + A (%) × Q (l / Hr) (1)

[Secondary recovery] A (%) × x (l / Hr) + C (%) × Q (l / Hr) = B (%) × x (l / Hr) + B (%) × Q (l / Hr) (2)

[3rd collection] B (%) × x (l / Hr) + G (%) × Q (l / Hr) = D (%) × x (l / Hr) + C (%) × Q (l / Hr) (3) where A: proportion of paint solids contained in the recovered water of the primary recovery tank 22-1 B: paint solids contained in the recovered water of the secondary recovery tank 22-2 Ratio C: Ratio of paint solids contained in the recovered water of the third collection tank 22-3 F: Ratio of paint solids contained in the paint in the electrodeposition tank Q: Amount of filtrate obtained by the filter x : Amount of liquid carried out by the work unit from the electrodeposition tank 10 and the recovery tanks 22-1 to 22-3 per unit time

The carry-out liquid amount x of the above-mentioned work is obtained as follows based on the above conditions D and E. x = 1500 m ² /Hr×0.2 l / m ² = 300 l / Hr On the other hand, the values of the solid content ratio F and the filtrate amount Q are as shown in the above conditions A and C, respectively.

Therefore, based on the values of F, Q and x and the above equations (1), (2) and (3), the solid paint content in the tanks 22-1 to 22-3 in the conventional water washing system. Ratio A ~
C is determined as follows.

A = 5.32% B = 1.65% C = 0.73% The paint recovery rate of this conventional water washing system is calculated as follows. Recovery efficiency = (20-0.73) / 20 = 96.35%

Next, the replenishment amount W of the pure water and the replenishment amount P of the electrodeposition paint in this conventional washing system will be described.
Based on the above conditions, the weight of the coating solids in the coating film (wet film) of the work tank discharged from the electrodeposition tank is 25 μ × 1.4 × 1 500 m ² / Hr × 10 ^-3 = 52.5% Is required. Therefore, the weight Y ′ of the coating film including the wet film moisture is calculated as Y ′ = 52.5 / (100-60) = 131.25 kg / Hr based on the moisture content of 60% of the above condition H.

The water content of the coating film is 78.75 k obtained by removing the solid weight of 52.5 kg / hr from 131.25 kg / hr.
Therefore, the volume Y of the coating material corresponding to the above weight Y ′ is Y = 52.5 / 1.4 based on the specific gravity of the coating material solids of 1.4 and the specific gravity of water 1 shown as the above conditions. + 78.75 / 1 = 116.25 l / Hr.

The liquid balance in the electrodeposition tank 10 is as follows: the carry-out amount x is 300 l / hr, the coating volume Y is 116.25 l / hr, and the filtrate amount is 120 under the condition c.
It is expressed by the following formula (4) based on 0 l / Hr and the evaporation amount of 75 l / Hr of the above condition.

116.25 + 300 + 1200 + 75 = 1200 + P + W (4)

On the other hand, the balance of the coating solid content in the electrodeposition tank 10 is as follows: the value of x is 300 l / Hr, the weight of coating film solid content is 52.5 kg / Hr, and the value of coating solid content F under the condition b is 20.
%, The value of the solid content ratio G of the filtrate under the condition B is 0.5%, the value of the filtrate amount under the condition C is 1200 / Hr, the recovery tank 22-
Based on the value of the solid content ratio A of 5.32% in 1 and the value of the solid content ratio of the above-mentioned condition 50, it is expressed by the following formula (5).

(52.5 / 1.4) + 300 × (20/100) + 1200 × (0.5 / 100) = 1200 × (5.32 / 100) + P × (50/100)… (5)

Therefore, the replenishment amount W of the pure water and the replenishment amount P of the electrodeposition paint are determined from the equations (4) and (5) as follows. W = 411.93 l / Hr P = 79.32 l / Hr

Next, the water washing system of the embodiment of the present invention shown in FIG. 2 will be considered. In the water washing system of the embodiment, the amount of overflow from the tanks 22-1 to 22-3 becomes the sum E of the filtrate Q and the amount W of makeup pure water, so that the following recovery water washing equilibrium equation is established. .

[Recovery primary] F (%) × x (l / Hr) + B (%) × E (l / Hr) = A (%) × x (l / Hr) + A (%) × E (l / Hr) (6)

[Secondary Recovery] A (%) × x (l / Hr) + C (%) × E (l / Hr) = B (%) × x (l / Hr) + B (%) × E (l / Hr) (7)

[3rd recovery] B (%) × x (l / Hr) + D (%) × E (l / Hr) = D (%) × x (l / Hr) + C (%) × E (l / Hr) (8) However, D: Proportion of paint solids contained in the mixture of filtrate and pure water

The value of the carry-out amount x in the above equations (6) to (8) is
As described above, the value of E is 300 l / Hr, and the value of E is 1200 l / Hr of the filtrate amount Q of the condition C and the value 41 of the makeup pure water amount W obtained in the conventional washing system.
Based on 1.93 l / Hr, it is calculated as follows. E = Q + W = 1200 + 411.93 = 1611.93 l / Hr

The values of the solid content ratio D are 1200 l / Hr of the filtrate amount Q and 411.9 of the supplementary pure water amount W.
It is determined as follows based on 3 l / Hr and the value of 0.5% of the solid content ratio G of the filtrate shown in the above condition b.

D = {(Q × 0.5 / 100) / (Q + W)} × 100 = 0.372%

Therefore, based on the above equations (6) to (7) and the values of F, E and D, the tank 22- of the apparatus of the above embodiment is
The paint solids proportions A to C in 1 to 22-3 are calculated as follows. A = 3.74% B = 0.71% C = 0.14%

The recovery efficiency of the apparatus of this embodiment is
It looks like this:

Recovery efficiency = {(F-D) / F} × 100 = {(2
0-0.372) / 20} × 100 = 98.1%

FIG. 4 is a table showing the ratios A, B and C and the recovery efficiency in the conventional apparatus and the apparatus according to the above embodiment. As is clear from the table, according to the device of the present invention, the amount of the coating solid component contained in the recovered primary water, the recovered secondary water and the recovered tertiary water is significantly smaller than that of the conventional device, and therefore high. A cleaning effect is obtained, and as a result, the amount of paint taken out is reduced and recovery efficiency is improved.

[0046]

According to the present invention, pure water for replenishment is mixed with the electrodeposition coating amount of the filtrate, and the mixed solution is sprayed from the spray unit provided corresponding to the last recovery tank. Therefore, the proportion of the paint solid component contained in the wash water in each recovery tank is reduced, and as a result, the amount of paint taken out is reduced and the paint recovery efficiency is improved.

Further, since a high cleaning action can be obtained, the yield of the paint can be improved and at the same time, the so-called 2
The quality of the coating film can be improved by preventing subsequent sagging. In addition, it is possible to reduce the load on the wastewater treatment facility in the cleaning process with pure water.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an embodiment of a water washing apparatus according to the present invention.

FIG. 2 is a flow chart of the water washing apparatus of the embodiment.

FIG. 3 is a flow chart of a conventional water washing device.

FIG. 4 is a table showing a ratio of paint solids and a paint recovery rate in each recovery tank in the conventional device and the device of the embodiment of the present invention.

[Explanation of symbols]

 10 Electrodeposition tank 11 Electrodeposition paint 21-1 to 21-3 Spray unit 22-1 to 22-3 Recovery tank 23 Filter

Claims (1)

[Claims] 1. A filtering means for introducing an electrodeposition coating material in an electrodeposition tank to separate the recovered coating material and a filtrate, and a plurality of stages arranged behind the electrodeposition tank to perform electrodeposition coating in the electrodeposition tank. A plurality of spray units for spraying cleaning water onto the coated product, and a plurality of recovery tanks provided corresponding to the spray units, for recovering the sprayed cleaning liquid from the spray units; Using the filtrate as the wash water, and while flowing the wash water that overflows from the recovery tank excluding the first-stage recovery tank into the cleaning tank located immediately before the recovery tank, In a water washing device for an electrodeposition-coated product, which is configured to allow the washing water overflowing from the foremost recovery tank to flow into the electrodeposition tank, the filtrate is mixed with pure water for replenishment. Before the mixed solution is installed in the last recovery tank. A means for supplying cleaning water to the spray unit is provided, and the cleaning liquid in the recovery tanks other than the last-stage recovery tank is supplied to the spray units provided corresponding to those recovery tanks. A water washing device for electrodeposited products.