JP2005249605A - Electroconductivity measuring method of electrodeposition coating and control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To find out an electroconductivity measuring method capable of confinuously measuring electroconductivity of electrodeposition coating to control the electrodeposition coating. <P>SOLUTION: The electroconductivity measuring method of the electrodeposition coating is characterized by moving the electrodeposition coating in piping, which constitutes a circulating cannel along with an electrodeposition coating tank at a constant flow velocity of 0.01-0.7 m/sec and providing an electrode free electromagnetic type electroconductivity meter to measure of the electroconductivity of the electrodeposition coating. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electric conductivity measurement method and a management method for an electrodeposition paint capable of continuously measuring the electric conductivity of the electrodeposition paint.

  Conventionally, electrodeposition paints are used as undercoats for automobile bodies and parts, and are used in many painting lines. Such a coating line is an automation that fills an electrodeposition tank with an electrodeposition paint, conveys the object to be coated on a conveyor, etc., applies a voltage, performs electrodeposition coating, and then baked and dried to obtain a coating film. The car body is painted continuously and the paint is taken out, and when a certain number of paints are counted, the paint is replenished to maintain a certain electrodeposition paint characteristic.

  To measure electrodeposition paint properties (eg, pH, conductivity, solids, pigment content, acid concentration), sample the electrodeposition paint bath from the electrodeposition paint tank and bring the paint back to the laboratory for electricity. We were looking for paint properties. However, it took 1 hour to 3 days to gather these data. In the meantime, the coating line continued to change, delaying line handling and causing abnormal finishes.

  Among these electrodeposition coating properties, the conductivity is measured by, for example, WM-50EG, CM-30G (product name, manufactured by Toa DKK Corporation), DS-12, DS-14 (product name, manufactured by HORIBA), etc. Measure using a rate meter. In these conductivity meters, an electrode such as a platinum plate and a cell are immersed in a sample solution, and the impedance between the electrode and the cell is measured to obtain the conductivity of the solution.

  As a conventional invention, there has been proposed a painting facility system in which a conductivity meter is installed in a painting line, the conductivity is measured, and the data is distributed and managed to a remote manager [Patent Document 1]. However, in the above system, when the conductivity is measured continuously and over a long period of time, the measurement value may vary due to contamination or defect of the electrode or cell, and may not be stably obtained.

  In addition, a conductivity meter has been proposed for the purpose of measuring the conductivity of a liquid [Patent Document 2]. When this conductivity meter is simply installed in the piping of the coating line of the electrodeposition paint bath and used for the measurement of conductivity, the electrodeposition paint has a paint solid content as low as 15 to 25% by weight, so the pigment is in the pipe. There is a problem that it tends to settle. In addition, when a pump is installed for the purpose of giving a constant flow rate in the pipe to prevent sedimentation of the pigment, the aggregation of paint may cause an error in the measured value of conductivity.

Because of this, even if it is installed in the electrodeposition paint coating line, there is no electrode or cell contamination or loss, it can be measured continuously, and the conductivity can be measured without maintenance over a long period of time. There has been a need for a method for measuring the conductivity of a bath.
JP 2003-13289 A US Pat. No. 5,157,332

  The problem to be solved by the invention is that even if it is installed in the electrodeposition paint coating line, there is no contamination or loss of electrodes or cells, it can be continuously measured, and the conductivity can be measured without maintenance over a long period of time. It is to find a method for measuring the conductivity of an electrodeposition paint that can be measured.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have made use of an apparatus comprising an electrodeless electromagnetic induction type conductivity meter (A) and a pipe (B) for circulating electrodeposition paint. The inventors have found that the conductivity of the electrodeposition paint can be continuously measured, and have completed the invention.

That is, the present invention
1. Moving the paint at a constant flow rate in the range of 0.01 to 0.7 m / sec in a pipe that forms a circulation path together with the electrodeposition paint tank;
A method of measuring the conductivity of an electrodeposition paint, comprising: providing an electrodeless electromagnetic induction type conductivity meter in the pipe; and measuring the conductivity of the paint;
2. The method for measuring conductivity of an electrodeposition paint according to claim 1, wherein the electrodeless electromagnetic induction type conductivity meter is an electromagnetic induction type electrodeless conductivity meter having a transmission coil and a reception coil.
3. The method for measuring the conductivity of an electrodeposition paint according to claim 1, wherein a pump without a sliding portion where the paint rubs is provided in the pipe in order to obtain a constant flow rate of the electrodeposition paint in the pipe.
4). The transmission coil and the reception coil in the electrodeless electromagnetic induction type conductivity meter (A) are arranged outside the pipe (B) for circulating the electrodeposition paint bath. A method of measuring the conductivity of the electrodeposition paint according to claim 1,
5). The pipe inner diameter of the pipe is 1 mmφ to 100 mmφ, and the method for measuring the conductivity of the electrodeposition paint bath according to claim 1,
6). The electric conductivity of the electrodeposition paint according to any one of claims 1 to 5, wherein the electric conductivity range measurable by the electrodeless electromagnetic induction type electric conductivity meter (A) is 500 µS / cm to 2500 µS / cm. Measuring method,
7). An electrodeposition paint bath for managing the electrodeposition paint bath by distributing the conductivity data obtained by using the method for measuring the conductivity of the electrodeposition paint according to any one of claims 1 to 6 through a communication line. How to manage,
8). A method for managing an electrodeposition paint bath using the method for measuring conductivity of an electrodeposition paint according to any one of claims 1 to 6,
About.

The method for measuring the conductivity of the electrodeposition paint according to the present invention does not require maintenance such as cleaning of the electrodes, and can measure the conductivity continuously and over a long period of time on the coating line of the electrodeposition paint. In the conventional method of measuring the conductivity by immersing the electrode or cell of the conductivity meter in the paint,
Although cleaning after measurement was necessary, in the present invention, cleaning after measurement is no longer necessary.

  Furthermore, in the present invention, it is possible to grasp the conductivity of the electrodeposition paint in a timely manner by transmitting and receiving measurement data via a communication line such as the Internet. In the painting line, since the conductivity of the electrodeposition paint can be grasped continuously, it is possible to predict changes in throwing power and film thickness and contribute to the supply of products having excellent coating film performance.

  The method for measuring the conductivity of the electrodeposition paint according to the present invention is shown in FIG. 1 as a model diagram, and a pipe (8) for circulating the electrodeless conductivity meter (1) and the paint in the electrodeposition paint bath. The conductivity of the electrodeposition paint can be continuously measured. Furthermore, in order to obtain a constant flow rate in the pipe, a constant flow rate can be given in the pipe by installing a pump (10) characterized in that there is no sliding portion where the electrodeposition paint rubs. .

  As an example of this pump, there may be mentioned a pump characterized in that there is no rubbing portion in the pump when the impeller floats by magnetism and the pump is rotated when circulating the electrodeposition paint.

  An example of a commercially available pump is a rehydro pump (trade name, manufactured by Iwaki Co., Ltd.). By using such a pump, the problem of agglomeration of the electrodeposition paint can be solved, and more accurate conductivity can be obtained.

  The electrodeless electromagnetic induction type conductivity meter (1) generates a magnetic field (6) by passing an alternating current through the transmitter coil (2) by the transmitter (4), and a voltage generated by electromagnetic induction by the receiver coil (3). (V) is measured by detector (5). From the value of the voltage (V), the conductivity of the electrodeposition paint bath (9) flowing through the pipe (8) can be obtained.

  FIG. 2 shows the details of an example of the electrodeless electromagnetic induction type conductivity meter (1). The type shown in FIG. 2 is a type having two transmission coils (2), and detects a voltage (V) generated by electromagnetic induction in the reception coil (3). Next, alternating current is sent from the transmitter (4) (not shown) to the transmission coil (2) through the cable (21), and the voltage (V) generated on the reception coil (3) side by electromagnetic induction is applied to the cable ( 22) and detected by a detector (5) (not shown) and converted to conductivity.

  FIG. 3 shows a model diagram in which an electrodeless electromagnetic induction type conductivity meter (1) is installed in a pipe, and the transmission coil and the reception coil in the electrodeless conductivity meter (1) are composed of an electrodeposition paint bath. Because it is arranged outside the pipe (8) for circulating the paint, and the conductivity can be measured without bringing the electrode into contact with the paint, it is possible to obtain accurate measurement values without contamination or defects of the electrode or cell. It is something that can be done. Therefore, even if it is installed in the painting line, the conductivity can be measured continuously.

  As shown in FIG. 3, the electrodeless electromagnetic induction conductivity meter (1) is attached around the pipe and does not directly contact the electrodeposition paint as shown in FIG. The material of the pipe includes stainless steel, copper, galvanized pipe, etc., but generally stainless steel is often used.

  As a commercial item of said electrodeless electromagnetic induction type conductivity meter (1), sensor 871FT series (The product name, an electrodeless conductivity meter by Foxboro Company) is mentioned.

  Specifically, 871FT-1C (tube inner diameter 1/2 inch (note), 1,000 μS / cm to 2,000 mS / cm), 871FT-1D (tube inner diameter 3/4 inch, conductivity measurement range 500 μS / cm ˜2,000 mS / cm), 871FT-1E (tube inner diameter 1 inch, conductivity measurement range 500 μS / cm to 2,000 mS / cm), 871FT-1F (tube inner diameter, 1-1 / 2 inch, conductivity measurement range 100 μS / cm to 1,000 mS / cm), 871FT-1G (tube inner diameter 2 inches, conductivity measurement range 100 μS / cm to 1,000 mS / cm), 871FT-1H (tube inner diameter 3 inches, conductivity measurement range 100 μS / cm to 1,000 mS / cm), 871FT-1J (tube inner diameter: 4 inches, conductivity measurement range: 50 μS / cm to 500 mS / cm), etc. I can get lost.

  When these products were simply applied to electrodeposition paints, the electrical conductivity could not be obtained accurately due to the sedimentation of pigments and the minute paint aggregation caused by mechanical share. In addition, the inventors have been able to measure the electric conductivity over a long period of time by finding out by the inventors and others.

(Note) 1 inch = approximately 25.4mm
The conductivity data of the electrodeposition paint obtained from the electrodeless electromagnetic induction conductivity meter (1) in Fig. 1 can be taken into a personal computer or the like through the external output (30), and via a communication line such as the Internet. By distributing the measurement data to a remote location, the characteristics of the electrodeposition paint bath can be managed remotely.

  The pipe inner diameter of the pipe (8) for circulating the electrodeposition paint is preferably in the range of 1 mmφ to 100 mmφ, preferably 10 mmφ to 80 mmφ, so that the electrodeposition paint is not sunk and is circulated at a constant flow rate. . The flow rate of the electrodeposition paint in the pipe has a good range in which the electrodeposition paint can be measured stably without the paint being settled in the pipe (8). The flow rate is 0.01 m / sec to 0.7 m / sec. The electroconductivity is measured by circulating (7) the electrodeposition paint from the electrodeposition paint bath (9) through which the pressure is preferably 0.1 m / sec to 0.5 m / sec.

  Since the conductivity measuring method of the present invention can eliminate electrode contamination and defects even when installed in a coating line, it has become possible to measure the conductivity in the coating line continuously and over a long period of time.

  For example, the conductivity of the electrodeposition paint yesterday was 1,550 μS / cm, but since an organic acid was added to the electrodeposition paint, the conductivity is 1,650 μS / cm today. Or, since the conductivity is suddenly reduced to 1,400 μS / cm, discarding of the filtrate and the polar liquid is suppressed. Alternatively, since the electrical conductivity has increased to 1,750 μS / cm, the filtrate and polar liquid are discarded. Can now be determined in a short time.

  The method of measuring the conductivity of the electrodeposition paint according to the present invention is not limited to measuring the conductivity by installing it in the painting line. Measurement is possible.

About electrodeposition paints:
As the electrodeposition paint applicable to the present invention, a conventionally known electrodeposition paint can be used, and either a cationic electrodeposition paint or an anion electrodeposition paint may be used. The cation electrodeposition paint is explained as the mainstream.

  The cationic electrodeposition paint uses, for example, an amine addition type epoxy resin or an amine addition type acrylic resin as a base resin, for example, a blocked polyisocyanate as a curing agent, a surface conditioner, a catalyst, a surfactant, an organic solvent, An emulsion prepared by adding an organic acid and dispersing in water and a pigment paste obtained by dispersing a pigment, a extender pigment, and a catalyst together with a dispersion resin, and diluting with deionized water can be exemplified.

The solid content of such a cationic electrodeposition coating is usually 0.1 to 40% by weight, preferably 5 to 30% by weight, more preferably 15 to 25% by weight, and pH is preferably 5.0 to 7.5. Is in the range of 5.5 to 7.0, and the conductivity is 1,000 μS / cm to 2,500 μS / cm, preferably 1,300 μS / cm to 2,200 μS / cm, more preferably 1,500 μS / cm to 2, The range is 000 μS / cm. The amount of the electrodeposition paint required for measurement in the present invention, 10Ml～300m ^3, preferably between 100Ml～200m ^3, it can be applied as long secure the flow rate to the extent that the paint does not settle in the piping, paint It can be installed on the line to measure continuous conductivity. The electrical conductivity measurement method of the present invention is not limited to the electrical conductivity measurement of electrodeposition paints, but can also be applied to electrical conductivity measurements of, for example, polar solutions, chemical conversion solutions, UF filtrates and the like in diaphragm electrodes.

  Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited thereby. “Parts” and “%” indicate “parts by weight” and “% by weight”.

Example 1
In the painting line A, a sensor 871FT-1E (manufactured by Foxboro Company, trade name, electrodeless electromagnetic induction conductivity meter) is installed in the piping of the painting line as shown in FIG. 3, and the electrodeposition paint is flowed into the piping. The electric conductivity of the electrodeposition paint was automatically measured by flowing at 0.3 m / sec. As a result, data with conductivity = 1,550 μS / cm was obtained. After the measurement of the conductivity, the sensing part of the conductivity is not in contact with the paint, so that it can be continuously measured without the need for cleaning.

Example 2
In painting line B, sensor 871FT-1E (manufactured by Foxboro Company, trade name, electrodeless electromagnetic induction conductivity meter), and rehydro pump (manufactured by Iwaki, trade name, pump characterized by no sliding part) Was installed as shown in (10) of FIG. 1, and the conductivity of the electrodeposition paint was automatically measured by flowing the electrodeposition paint through the pipe at a flow rate of 0.5 m / sec.

  Conductivity is measured 3 times a day when the painting line is in operation, every 3 hours, the first conductivity = 1,650 μS / cm, the second conductivity = 1,670 μS / cm, the third conductivity The degree = 1,660 μS / cm was automatically measured and distributed via the Internet to the remote paint manager. After the measurement of the conductivity, the sensing part of the conductivity is not in contact with the paint, so that it can be continuously measured without the need for cleaning.

Comparative Example 1
The electrodeposition paint of the same painting line A as in Example 1 was sampled and transported to the laboratory. Next, conductivity = 1,550 μS / cm was measured using CM-30G (manufactured by Toa DKK Corporation, trade name, conductivity meter). After measuring the conductivity, the electrode was washed to prepare for the next measurement.

Comparative Example 2
The electrodeposition paint of the same painting line B as in Example 2 was sampled every 3 hours from the electrodeposition paint to conduct conductivity three times a day. Next, after using CM-30G (trade name, conductivity meter manufactured by Toa DKK Co., Ltd.) to obtain the first conductivity = 1,650 μS / cm, the electrode was then washed, 670 μS / cm was obtained. Next, the electrode was washed again and measured to obtain the first 1,660 μS / cm. After measuring the conductivity, the electrode was washed to prepare for the next measurement.

  The present invention can continuously calculate the conductivity of the electrodeposition paint bath. For example, since it is possible to immediately take measures against changes in the electrodeposition paint in the painting line, it is possible to supply coated articles with excellent quality.

It is a model figure of the electrical conductivity measurement method of an electrodeposition coating material. It is the model figure which showed the inside of an electrodeless type electromagnetic induction type conductivity meter. It is a model figure of the external appearance of an electrodeless electromagnetic induction type conductivity meter.

Explanation of symbols

1. 1. Electrodeless electromagnetic induction type conductivity meter 2. Transmitting coil 3. Receive coil Transmitter 5. Detector 6. Magnetic field 7. Flow of electrodeposition paint 8. Piping 9. Electrodeposition bath 10 Pump having no sliding part 20. Resin for protection 21. Cable to transmitter 22. Cable to detector 30. Cable for external output

Claims (8)

Moving the paint at a constant flow rate in the range of 0.01 to 0.7 m / sec in a pipe that forms a circulation path together with the electrodeposition paint tank;
A method for measuring the conductivity of an electrodeposition paint, comprising: providing an electrodeless electromagnetic induction type conductivity meter in the pipe; and measuring the conductivity of the paint.     The method for measuring conductivity of an electrodeposition paint according to claim 1, wherein the electrodeless electromagnetic induction type conductivity meter is an electromagnetic induction type electrodeless conductivity meter having a transmission coil and a reception coil.     The method for measuring the conductivity of an electrodeposition paint according to claim 1, wherein a pump is provided in the pipe without a sliding portion where the paint rubs in order to obtain a constant flow rate of the electrodeposition paint in the pipe.     The transmission coil and the reception coil in the electrodeless electromagnetic induction type conductivity meter (A) are arranged outside the pipe (B) for circulating the electrodeposition paint bath. The electrical conductivity measurement method of the electrodeposition paint as described in 2.   The method for measuring the conductivity of an electrodeposition paint bath according to any one of claims 1 to 4, wherein the pipe has an inner diameter of 1 mm to 100 mm.   The electric conductivity of the electrodeposition paint according to any one of claims 1 to 5, wherein the electric conductivity range measurable by the electrodeless electromagnetic induction type electric conductivity meter (A) is 500 µS / cm to 2500 µS / cm. Measuring method.   An electrodeposition paint bath for managing the electrodeposition paint bath by distributing the conductivity data obtained by using the method for measuring the conductivity of the electrodeposition paint according to any one of claims 1 to 6 through a communication line. Management method.   The management method of the electrodeposition paint bath using the electric conductivity measurement method of the electrodeposition paint of any one of Claims 1-6.

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