JPH0651270U - Electro-deposition coating device - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent clogging of the diaphragm to ensure long-term stable operation of the diaphragm electrode device and a high quality coating film. A metal ion concentration monitoring means 40 is provided for detecting the concentration of iron ions eluted from the electrode 18 in the diaphragm structure 10A into the polar liquid and determining whether or not the detected concentration exceeds a set value below the precipitation concentration. It has a different structure.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an electrodeposition coating device.

[0002]

[Prior art]

 FIG. 2 is a diagram showing a schematic structure of a conventional electrodeposition coating apparatus, and FIG. 3 is a diagram for explaining the diaphragm electrode apparatus.

In FIG. 2, 1 is an electrodeposition tank, 3 is a transporting device for transporting an object W to be coated such as an automobile body, 18 is a stainless steel electrode, and 19 is a power supply device. The electrodeposition tank 1 contains an electrodeposition coating liquid. The electrodeposition coating liquid is composed of a cationic paint and an acetic acid aqueous solution. Therefore, when the object W to be coated is connected to the negative electrode (−) of the power supply device 19 and the electrode 18 is connected to the positive electrode (+) of the power supply device 19, a coating film can be formed on the surface of the object W to be coated.

Here, the diaphragm electrode device (10, 20) is provided in order to prevent metal ions (mainly iron ions) eluted from the electrode 18 into the polar liquid from being mixed into the electrodeposition coating liquid. For example, the structure is disclosed in Japanese Utility Model Laid-Open No. 64-53767.

That is, as shown in FIGS. 2 and 3, the diaphragm electrode device includes a diaphragm electrode structure 10 including an electrode 18 and a diaphragm structure 10 A (a tubular diaphragm 11, a holding member 12, etc.) having the electrode 18 built therein. The diaphragm electrode structure 10 includes a polar liquid management unit 20 that circulates the polar liquid through a piping system 30 (a polar liquid supply pipe 31, a polar liquid returning pipe 32, etc.), and during electrodeposition coating operation. It is formed so as to keep the polar liquid property (conductivity) in the diaphragm structure 10A constant.

[0006]

[Problems to be solved by the device]

Now, paying attention to the inside and outside of the diaphragm electrode structure 10 during electrodeposition coating, the acid (CH ₃ COO ⁻ ) flows into the diaphragm structure 10A through the diaphragm (anion exchange membrane) 11. On the other hand, a coating film (NH ⁺ ) is formed on the article W to be coated. At this time, the metal ions (Fe ²⁺ etc.) eluted from the electrode 18 into the polar liquid are blocked by the diaphragm 11 from flowing out of the diaphragm structure 10A.

Here, when electrodeposition coating is performed for a certain period (period) using the diaphragm electrode device, metal ions (mainly Fe ²⁺ ) are precipitated from the polar liquid in the diaphragm structure 10A, and iron bacteria, etc. Is oxidized by the action of and adheres to the diaphragm 11 as insoluble iron oxide (iron hydroxide) or precipitates on the bottom surface of the holding member 12.

When such a situation occurs, no matter how carefully the polar liquid property is managed by the polar liquid management unit 20, fluctuation or attenuation of the energizing current is caused, smooth coating is hindered and coating film quality deteriorates. Will end up. Therefore, conventionally, the electrodeposition coating line is stopped regularly (usually after 60 days have elapsed) and the diaphragm 11 of the diaphragm electrode structure 10 is replaced. However, the replacement work of the diaphragm 11 is troublesome and is a neck for improving the production efficiency.

In view of the above circumstances, an object of the present invention is to provide an electrodeposition coating apparatus capable of preventing clogging of the diaphragm and ensuring long-term stable operation of the diaphragm electrode apparatus and a high quality coating film. It is in.

[0010]

[Means for Solving the Problems]

 The electrodeposition coating apparatus according to the present invention is equipped with a diaphragm electrode device including a diaphragm electrode structure in which electrodes are arranged in the diaphragm structure and a polar liquid management unit for circulating and circulating the polar liquid in the diaphragm electrode structure. The coating device was equipped with a metal ion concentration monitoring means for detecting the concentration of metal ions eluted in the polar liquid from the electrodes in the diaphragm structure and determining whether the detected concentration exceeded a set value below the precipitation concentration. It is characterized by

[0011]

[Action]

 In the present invention having the above-mentioned configuration, when the electrode of the diaphragm electrode device and the other electrode (the object to be coated) are energized to perform electrodeposition coating on the surface of the object to be coated, metal ions such as iron ions are Elute into. The metal ion concentration is detected by the metal ion concentration monitoring means, and it is determined whether or not the detected concentration exceeds a set value equal to or lower than the precipitation concentration.

[0012] Therefore, based on the determination result that the detection concentration of the metal ion concentration monitoring means exceeds the set value, a part (or all) of the polar liquid is replaced and the iron oxide (iron hydroxide) ) It is possible to prevent the adherence of the like.

As a result, it is possible to prevent clogging of the diaphragm of the diaphragm electrode structure and ensure stable long-term operation of the diaphragm electrode device and a high quality coating film.

[0014]

【Example】

 FIG. 1 is a diagram showing a schematic configuration of the present electrodeposition coating apparatus. An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the present electrodeposition coating apparatus has a basic configuration [electrodeposition tank 1, diaphragm electrode device (diaphragm electrode structure 10, polar liquid management unit 20 and piping system 30), etc.] as a conventional example (FIG. The same as 3), the concentration of metal ions such as iron ions eluted in the polar liquid from the electrode 18 in the diaphragm electrode structure 10A is detected, and the detected concentration is set to a value equal to or lower than the precipitation concentration (setting). The metal ion concentration monitoring means 40 for determining whether or not the value exceeds the value is provided. The same components as those in the conventional example (FIGS. 2 and 3) are designated by the same reference numerals, and the description thereof will be omitted or simplified.

First, the diaphragm electrode structure 10 is arranged in the electrodeposition tank 1 (only one unit is shown in FIG. 1) to form a counter electrode for another electrode (the object W to be coated). The structure is such that a holding member 12, a diaphragm 11 formed by injection-molding a certain polymer material supported by the holding member 12 in a tubular shape, and a cylindrical shape made of a stainless steel held in the diaphragm 11. And electrode 18.

The polar liquid management unit 20 is composed of a polar liquid tank 21, a pure water supply tank 23, a flow rate adjusting valve 25, a conductivity detecting sensor 27 and a setting device 26, and the flow amount is set based on the setting of the setting device 26. The adjusting valve 25 is controlled so that the electric conductivity of the polar liquid in the polar liquid tank 21 can be kept constant.

Further, valves V1 and V2 are inserted in the middle of the polar liquid supply pipe 31 and the polar liquid return pipe 32 of the piping system 30, respectively. Further, a discharge conduit 39 for discharging the polar liquid in the diaphragm structure 10A to the outside is connected in the middle of the polar liquid return conduit 32, that is, between the discharge port 12A of the holding member 12 and the valve V2. A valve V3 is inserted in the middle of the pipeline 39.

Further, the metal ion concentration monitoring means 40, which is a feature of the present electrodeposition coating apparatus, is a main iron ion among the metal ions eluted from the electrode 18 of the diaphragm electrode structure 10 into the polar liquid during electrodeposition coating. It is means for detecting the concentration of ions (Fe ²⁺ ) and determining whether or not the detected concentration exceeds a value (set value) set below the precipitation concentration.

In this embodiment, the precipitation concentration (5 ppm) of iron ions (Fe ²⁺ ) is selected as the “set value”. Here, the metal ion concentration monitoring means 40 is an iron ion concentration detection sensor 41 that detects the concentration of iron ions (Fe ²⁺ ) in the polar liquid in the diaphragm structure 10A, and a detection of the iron ion concentration detection sensor 41. Based on the result (detected concentration), it is judged whether or not the concentration exceeds the set value (several ppm). If it exceeds, the valve V 2 is closed and the valve V 3 is opened. It comprises a determination means 45 for opening the valve V2 and closing the valve V3. In the present embodiment, the judging means 45 is configured by utilizing a part of the function of the control device for driving and controlling the entire electrodeposition coating device. In FIG. 1, reference numeral 35 is a circulation pump of the piping system 30.

Next, the operation of this embodiment will be described. When the electrode 18 of the diaphragm electrode structure 10 and the other electrode (the object W to be coated) are energized to perform electrodeposition coating on the surface of the object W to be coated, iron ions (Fe ²⁺ ) and the like are eluted from the electrode 18. The iron ion (Fe ²⁺ ) concentration is detected by the iron ion concentration detection sensor 41. The determination means 45 determines whether the concentration detected by the sensor 41 exceeds a set value (several ppm).

When the determination means 45 determines that the detected value exceeds the set value, the valve V2 is closed and the valve V3 is opened to discharge the polar liquid in the diaphragm structure 10A to the outside. In addition, fresh polar liquid is replenished into the diaphragm structure 10A from the polar liquid management unit 20 by the amount discharged to the outside. When the detected value becomes equal to or less than the set value, the judging means 45 opens the valve V2 and closes the valve V3 to resume normal polar liquid circulation.

Since part of the polar liquid is automatically replaced, the iron ion concentration in the diaphragm structure 10A does not exceed the set value, and insoluble iron oxide (iron hydroxide) adheres to the diaphragm 11. The electrode efficiency will not decrease.

According to this embodiment, however, the concentration of iron ions dissolved in the polar liquid from the electrode 18 in the diaphragm structure 10A is detected and whether or not the detected concentration exceeds the set value (several ppm). Since the configuration is provided with the metal ion concentration monitoring means 40 for determining, it is possible to prevent the diaphragm 18 from being clogged and ensure a long-term stable operation of the diaphragm electrode device and a high quality coating film.

Further, since the diaphragm 11 is not pulled out of the tank for cleaning, the diaphragm 11 is not damaged, and the life of the diaphragm 11 itself can be substantially extended, which is economical.

In addition, in the above embodiment, a part of the polar liquid in the diaphragm structure 10A is automatically replaced, but the point is that the inside of the diaphragm structure 10A is determined based on the determination result of the metal ion concentration monitoring means 40. It suffices that the iron ion concentration in (1) can be maintained so as not to exceed the set value, so that part (or all) of the polar liquid may be replaced manually.

[0026]

[Effect of device]

 According to the present invention, a metal ion concentration monitoring means is provided for detecting the concentration of metal ions eluted in the polar liquid from the electrode in the diaphragm structure and determining whether or not the detected concentration exceeds the set value below the precipitation concentration. With this configuration, it is possible to prevent clogging of the diaphragm and ensure long-term stable operation of the diaphragm electrode device and a high quality coating film.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an essential part of an embodiment of the present invention.

FIG. 2 is a diagram showing an overall configuration of a conventional electrodeposition coating apparatus.

FIG. 3 is a diagram for explaining a diaphragm electrode device of a conventional electrodeposition coating device.

[Explanation of symbols]

 10 diaphragm electrode structure 10A diaphragm structure 11 diaphragm 18 electrode 20 polar liquid management unit 40 metal ion concentration monitoring means

Claims (1)

[Scope of utility model registration request] 1. An electrodeposition coating apparatus comprising a diaphragm electrode device comprising a diaphragm electrode structure in which electrodes are arranged in the diaphragm structure and a polar liquid management unit for circulating and circulating the polar liquid in the diaphragm electrode structure. Electrode characterized by being provided with a metal ion concentration monitoring means for detecting the concentration of metal ions eluted in the polar liquid from the electrodes in the structure and determining whether or not the detected concentration exceeds a set value below the precipitation concentration. Coating equipment.