JP4096922B2 - Coating pretreatment method and coating pretreatment apparatus - Google Patents

Description

  The present invention relates to a pretreatment method and a paint pretreatment apparatus which are performed before electrodeposition coating is applied to the surfaces of automobile bodies and parts.

  Electrodeposition coating is generally used as an undercoat for automobile bodies, but before this electrodeposition coating is applied, so-called pretreatment is performed in which the automobile body is washed or a chemical conversion film is formed.

  Conventional electrodeposition coating pretreatment includes degreasing and cleaning processes to remove oil, iron powder, dust, etc. adhering to the car body, and surface adjustment to form a zinc phosphate conversion coating on the cleaned body surface.・ It consists of a chemical conversion treatment process. Of these, the surface conditioning process increases the number of reaction starting points in the next zinc phosphate-based chemical conversion treatment process by adsorbing the surface conditioning agent component on the surface of the object to be treated. It plays the role of accelerating the film-forming reaction, becoming the nucleus of the zinc phosphate film crystal.

  However, in the zinc phosphate chemical conversion treatment method, the surface adjustment step is necessary as described above in order to accelerate the formation reaction of the chemical conversion film. In addition, since the zinc phosphate chemical conversion treatment method forms a chemical conversion film by a chemical reaction, chemical conversion sludge is inevitably generated, and for this reason, a wastewater treatment device containing chemical conversion sludge, a cleaning device for cleaning the body, and Equipment such as a draining and drying furnace is required.

The present invention can shorten the chemical pretreatment process by simplifying the chemical conversion treatment process for forming a chemical conversion film before electrodeposition coating , and also closes the drainage system of the chemical conversion treatment process and discharges waste liquid. reducing an object to provide a can be Ru coating pretreatment method and coating pretreatment system.
In order to achieve the above object, according to the present invention,
A pre-painting method for chemical conversion treatment of an object to be treated before electrodeposition coating,
The chemical conversion treatment is
A film forming step of forming a chemical conversion film by bringing a chemical conversion treatment solution containing zirconium ions into contact with an object to be processed after degreasing and cleaning;
And having a pure water cleaning step for cleaning by bringing pure water into contact with the object to be treated after the coating is formed,
The pure water cleaning step includes a step of recovering excess chemical conversion treatment liquid adhering to the object to be processed and pure water after cleaning, and returning the recovered chemical conversion treatment liquid to the film forming step. A pre-painting method is provided.

Moreover, according to the present invention,
A coating pretreatment device installed in the pre-process of the electrodeposition coating device ,
A film forming means for forming a chemical conversion film by bringing a chemical conversion treatment solution containing zirconium ions into contact with an object to be processed after degreasing and cleaning;
This is disposed downstream of the film forming means and cleaned by bringing pure water into contact with the object to be processed after forming the film, and recovers excess chemical conversion treatment liquid adhering to the object to be processed together with the pure water after cleaning. Pure water cleaning means,
The pure water cleaning means is provided with a coating pretreatment apparatus to which a return piping for guiding the recovered excess chemical conversion treatment liquid and the cleaned pure water to the film forming means is connected .

In the present invention, since a chemical conversion treatment solution containing zirconium ions and substantially free of phosphate ions is used, a surface adjustment step before chemical conversion treatment and a cleaning step with industrial water after chemical conversion treatment are unnecessary, and chemical conversion treatment is performed. Can be simplified. As a result, the coating pretreatment can be shortened. Further, in the present invention, there is a pure water cleaning step in which the object to be processed on which the chemical conversion film is formed in the film forming step is cleaned with pure water. In this pure water cleaning step, the extraneous matter adhering to the object to be processed after the film is formed The chemical conversion treatment liquid is recovered together with the pure water after washing, and the recovered chemical conversion treatment liquid is returned to the film forming step, so that the drainage system of the chemical conversion treatment step is closed. As a result, discharge of waste liquid to the outside can be reduced, and the risk of causing environmental problems is reduced.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a plan layout view showing an example of a coating process to which a pre-painting treatment method and a pre-treatment device of the present invention are applied, and FIG. 2 shows an embodiment of the pre-painting method and pre-painting device of the present invention. FIG. 3 is a side view, and FIG. 3 is an apparatus configuration diagram showing an embodiment of a chemical conversion treatment apparatus according to the pre-painting treatment method and the pre-painting treatment apparatus of the present invention.

  FIG. 1 and FIG. 2 show an example of the pretreatment to the electrodeposition process in the painting process, and the first half of the painting line is outlined with reference to the same drawing. In the following description, the process of removing oil, iron powder, dust, etc. adhering to the white body and the generic name of the apparatus will be referred to as a degreasing cleaning process A or a degreasing cleaning apparatus A, and then a process of forming a chemical conversion coating on the white body. And a generic name of the apparatus is referred to as a chemical conversion treatment step B or a chemical conversion treatment apparatus B, and a process for forming an undried electrodeposition coating film on the body on which the chemical conversion film is formed and a generic name of the apparatus are referred to as an electrodeposition process C or electrodeposition. The coating device C is called the electrodeposition water washing step D or the electrodeposition water washing device D, and the process of washing off the excess electrodeposition paint adhering to the body after that is called the electrodeposition water washing step D or the electrodeposition water washing device D. A general term for the drying process and its apparatus is referred to as an electrodeposition baking process E or an electrodeposition drying furnace 28.

  First, the white body that has finished the assembly of the pressed parts is transferred from the carriage to the painting hanger 3 by the drop lifter 1 of the vehicle body assembly line, and conveyed to the painting line by the overhead conveyor 2.

  Since the white body 4 carried into the painting line is attached with press oil, iron powder by welding, and other dust, these oils, iron powder and dust are removed in the degreasing cleaning process A before chemical conversion treatment. Removed. In the example shown in the figure, the degreasing and cleaning step A is mainly performed in the preliminary degreasing step A1 and the main degreasing step A2 for removing oil, and the degreasing liquid and body 4 used in the preliminary degreasing step A1 and the main degreasing step A2. It consists of a first water washing step A3 and a second water washing step A4 for removing iron powder and dust adhering to.

  As shown in FIG. 2, the preliminary degreasing step A1 is a so-called shower-type liquid contact method in which the degreasing liquid stored in the tank 5 is pumped up and sprayed from the nozzle 6 toward the body 4. For A2, a so-called full dip type liquid contact method is adopted in which the body 4 is completely immersed in the degreasing liquid stored in the degreasing tank 7. However, the coating pretreatment method and apparatus according to the present invention are not limited to such a liquid contact method and the number of steps (in this example, two steps of preliminary degreasing and main degreasing), and can be changed as appropriate.

  In addition, the first water washing step A3 is a so-called shower type liquid contact method in which the working water stored in the tank 8 is pumped up and sprayed from the nozzle 9 toward the body 4, whereas the second water washing step A4 is A so-called full-dip type liquid contact method is adopted in which the body 4 is completely immersed in the working water accommodated in the washing tank 10 so as to contact the liquid. However, the coating pretreatment method and apparatus according to the present invention are not limited to such a liquid contact method and the number of stages (in this example, two stages of first water washing and second water washing), and can be appropriately changed. The apparatus constituting the degreasing and cleaning step A described above is the degreasing and cleaning apparatus A.

  In order to form a chemical conversion film on the surface of the white body 4 cleaned by the degreasing cleaning process A, a chemical conversion treatment process B is provided. The chemical conversion treatment process B of this example is composed of a chemical conversion film forming process B1 and a pure water washing process B2 for preventing rusting by the chemical conversion liquid, and no surface adjustment process is provided.

  In particular, in this example, a chemical conversion treatment liquid containing, for example, zirconium ions and / or titanium ions, and fluorine ions, and containing substantially no phosphate ions is used as the chemical conversion treatment liquid.

In the chemical conversion treatment containing phosphate ions, a chemical conversion film is formed by a precipitation reaction (chemical reaction) by ion exchange with iron, zinc, and aluminum constituting the body. For example, zirconium ions and / or titanium ions, and chemical conversion treatment by the chemical conversion treatment solution containing fluorine ions is not a film formation mechanism by chemical reaction, the use of chemical conversion treatment solution of this species, as compared with the case of using the zinc phosphate-based chemical conversion treatment solution, the chemical conversion It is advantageous in that sludge (reaction product) is not generated and a surface adjustment step is unnecessary.

For example, zirconium ions and / or titanium ions and fluorine ions are contained, the content of zirconium ions and / or titanium ions is 20 to 500 ppm on a weight basis, and the content of fluorine ions is zirconium ions. And / or a chemical conversion treatment solution having a molar ratio of 6 times or more with respect to titanium ions, substantially containing no phosphate ions, and having a pH of 2 to 5, or vanadium ions, cerium ions, nickel Chemical conversion solution with addition of rust preventive metal such as ion, manganese ion, cobalt ion, zirconium ion and / or titanium ion, fluorine ion, and soluble epoxy resin, zirconium ion and / or titanium ion content is 20 to 500 ppm on a mass basis, The content of iodine ion, relative zirconium ion and / or titanium ions, not less than 6 times by molar ratio, soluble epoxy resin, the resin 100g per -NH ₂ and / or _-NH ^{3 +} at least 0.1 A chemical conversion treatment solution having a molarity, substantially not containing phosphate ions, and having a pH of 2.5 to 4.5, hexavalent chromium ions of 2 g / liter or more, sulfate ions of 20 to 2000 ppm, fluorine of less than 400 ppm, And a chemical conversion treatment solution containing 20 to 1000 ppm of one or two ions selected from zirconium ions and titanium ions and having a pH of 0.5 to 2.0, or colloidal silica, dry silica, or alkali metal silicate. It is a chemical conversion treatment liquid containing 1 to 5 g / liter of one or more kinds of silica sols at a solid content concentration. However, it names intention to be limited only by the chemical conversion treatment solution.

  The chemical conversion treatment apparatus B shown in FIG. 3 has a treatment tank 11 through which a body 4 mounted on a coating hanger passes, and the body 4 is also up and down as the overhead conveyor 2 is raised and lowered. The body 4 can be immersed in the chemical conversion treatment liquid. In addition, although the so-called full dip type processing tank 11 is shown in the same figure, only the lower part of the body 4 is immersed and the half dip type in which the upper part of the body 4 is showered, or the entire body 4 is subjected to chemical conversion treatment by the shower method. It is also possible to adopt.

  In the chemical conversion treatment process using the above-described chemical conversion treatment solution containing zirconium ions, so-called chemical conversion sludge does not occur, and therefore it is not necessary to provide a special sludge removal device in the treatment tank 11. In this example, a circulation pipe 15 having a filter 12, a pump 13, and a discharge nozzle 14 is provided for the purpose of removing dust contained in the chemical conversion treatment liquid in the treatment tank 11 and stirring the chemical conversion treatment liquid.

  The chemical conversion liquid consumed in the processing tank 11 is replenished at a predetermined timing from the tank 16 that stores the chemical conversion treatment liquid for replenishment.

  A pure water washing step B2 is provided subsequent to the chemical conversion film forming step B1. In this pure water washing step B2, the pure water stored in the tank 17 is pumped up by the pump 18 as shown in FIG. This is a so-called shower-type liquid contact method in which the spray is sprayed in a mist shape toward 4. This pure water washing process B2 is for preventing the generation | occurrence | production of rust on a body by this by this, when the pH of a chemical conversion liquid is 2-5 and acidic as above-mentioned. Therefore, it is possible to omit the pure water washing step or reduce the spray amount as necessary.

  In particular, in this example, an overflow pipe 20 is provided that collects pure water sprayed on the body 4 in the tank 17 and guides the overflow water of the tank 17 to the treatment tank 11. When the automobile body 4 is immersed in the treatment tank 11 and the chemical conversion treatment is performed, in addition to the chemical conversion treatment liquid used for the treatment, there are not a few chemical conversion treatment liquids taken out to the next process by the body 4 as in this example. The chemical conversion treatment liquid taken out from the treatment tank 11 is collected in the tank 17 in the pure water washing step B2, and the overflowed liquid (chemical conversion treatment liquid + pure water) is returned to the treatment tank 11. The shortage in the treatment tank 11 is replenished from the replenishing chemical conversion liquid tank 16, and the shortage in the pure water tank 17 is replenished from the replenishment pure water tank 21. Thereby, the waste water treatment system of chemical conversion film formation process B1 and pure water washing process B2 is closed.

  The apparatus constituting the chemical conversion treatment process B described above is the chemical conversion treatment apparatus B.

  Returning to FIG. 1 and FIG. 2, after the pure water washing B2, an electrodeposition process C and an electrodeposition water washing process D are provided. In particular, in the pretreatment coating line of this example, the storage process of the body 4 is omitted between the chemical conversion treatment process B and the electrodeposition process C, and the body is allowed to flow directly to the electrodeposition process C even during lunch break or at the end of workday. I am going to do that. This also prevents rusting of the body 4 in addition to the pure water washing step B2 described above. However, a storage process can be provided as necessary.

  The electrodeposition step C is a step of forming an electrodeposition coating film on the surface of the body 4 by the electrophoretic action of the electrodeposition solution. The electrodeposition step C has a boat-shaped electrodeposition tank 22 filled with the electrodeposition solution, and the coating hanger 3 The body 4 is immersed in the electrodeposition liquid while being mounted on the electrode, and a high voltage is applied to a plurality of electrode plates (not shown) provided on the side wall and the low wall in the electrodeposition tank 22 and the body 4 Electrodeposition is applied by grounding the side. At this time, since the electrodeposition liquid enters the inside of the bag structure of the body 4, an electrodeposition coating film is also formed on the inner surface of the bag structure. As the electrodeposition liquid, the above-described cationic electrodeposition paint is preferably used for rust prevention, but an anionic electrodeposition paint that grounds the electrodeposition liquid side and applies a high voltage to the body 4 side may also be used. There is no problem.

  Subsequent to the electrodeposition step C, an electrodeposition water washing step D is provided in which excess electrodeposition liquid adhering to the body 4 is washed away and, if necessary, recovered. The electrodeposition rinsing process D of this example is composed of a preceding process of rinsing with industrial water and a subsequent process of rinsing with pure water, and FIG. The water washing process by the construction water is further constituted by full-dip washing and shower washing, a washing tank 23 filled with the construction water, a tank 24 in which the construction water is stored, and the construction water stored in the tank 24. Is pumped up and sprayed toward the body 4. Immediately after the shower type water washing process, although not shown in the drawing, similarly to the shower type water washing process, a tank for storing pure water and the pure water stored in the tank are pumped up by a pump. In addition, a pure water washing step having a nozzle that sprays in a mist toward the body 4 is provided.

  After the electrodeposition washing step D, as shown in FIG. 1, a drop lifter 26 is provided for transferring the body 4 mounted on the painting hanger 3 to the painting carriage, and the body transferred to the painting carriage here. 4 is carried into the coating and drying furnace 28 by the floor conveyor 27, and is heated at 170 ° C. for 20 minutes, for example, so that the electrodeposition coating film applied to the body 4 is cured. This coating drying furnace 28 corresponds to the electrodeposition baking process E.

  After the electrodeposition baking process E, a storage process F is provided for temporarily storing the body 4 at lunch break or at the end of work. During the lunch break or at the end of work, the body assembly process before the drop lifter 1 and the sealing process G after the electrodeposition baking process E are interrupted. On the other hand, if the process is interrupted from the degreasing and washing process A to the electrodeposition baking process E, the quality is often affected. Therefore, even if the body assembly process or the sealing process G is interrupted, the process is continued. This storage process F is a line for temporarily storing the body 4 processed during that time and supplying the body 4 to the sealing process G when the operation is resumed. For this reason, it is usually preferable to have a storage capacity of the number of bodies that are present before the degreasing cleaning step A to the electrodeposition baking step E.

  As described above, according to the present embodiment, the chemical conversion treatment liquid containing zirconium ions and / or titanium ions and fluorine ions and substantially not containing phosphate ions is used before chemical conversion treatment step B. A surface adjustment process becomes unnecessary, and the water washing process by industrial water becomes unnecessary after the chemical conversion treatment process B, and the chemical conversion treatment process can be simplified.

  Moreover, at this time, the drainage system of the chemical conversion treatment process B can be closed by returning the recovered overflow liquid of the pure water washing process B2 after the chemical conversion film forming process B1 to the chemical conversion treatment tank 11. Moreover, since there is no problem even if the pure water sprayed in this pure water washing process is brought into the electrodeposition process of the next process, it is not necessary to provide a draining and drying furnace in the chemical conversion treatment process B. It will function as pure water for replenishment of electrodeposition paint.

  The embodiment described above is described for facilitating the understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

It is a plane layout figure which shows an example of the coating process to which the coating pre-processing method and coating pre-processing apparatus of this invention are applied. It is a side view which shows one Embodiment of the coating pre-processing method and coating pre-processing apparatus of this invention. It is an apparatus block diagram which shows one Embodiment of the chemical conversion treatment apparatus which concerns on the coating pre-processing method and coating pre-processing apparatus of this invention.

Explanation of symbols

A ... Degreasing cleaning process B ... Chemical conversion treatment process C ... Electrodeposition process D ... Electrodeposition washing process E ... Electrodeposition baking process F ... Storage process G ... Sealing process 4 ... Automobile body (object to be treated)
17 ... Pure water tank 20 ... Overflow pipe

Claims (8)

A pre-painting method for chemical conversion treatment of an object to be treated before electrodeposition coating,
The chemical conversion treatment is
A film forming step of forming a chemical conversion film by bringing a chemical conversion treatment solution containing zirconium ions into contact with an object to be processed after degreasing and cleaning;
And having a pure water cleaning step for cleaning by bringing pure water into contact with the object to be treated after the coating is formed,
The pure water cleaning step includes a step of recovering excess chemical conversion treatment liquid adhering to the object to be processed and pure water after cleaning, and returning the recovered chemical conversion treatment liquid to the film forming step. Pre-painting method.   After collecting the excess chemical conversion liquid adhering to the object to be processed and the purified pure water in a pure water tank for storing pure water, the supernatant in the pure water tank is transferred to a processing tank for storing the chemical conversion liquid. The coating pretreatment method according to claim 1, wherein the coating pretreatment method is returned. 3. The coating pretreatment method according to claim 1 , wherein a shortage of pure water is replenished to the pure water cleaning step, and a shortage of chemical conversion solution is replenished to the film forming step . After performing the chemical conversion treatment, pretreatment method painting according to any one of claims 1-3, characterized in that to perform as electrodeposition coating without storage of the object to be processed. A coating pretreatment device installed in the pre-process of the electrodeposition coating device ,
A film forming means for forming a chemical conversion film by bringing a chemical conversion treatment solution containing zirconium ions into contact with an object to be processed after degreasing and cleaning;
This is disposed downstream of the film forming means and cleaned by bringing pure water into contact with the object to be processed after forming the film, and recovers excess chemical conversion treatment liquid adhering to the object to be processed together with the pure water after cleaning. Pure water cleaning means,
The pre-painting treatment apparatus, wherein the pure water cleaning means is connected with a return pipe for guiding the recovered excess chemical conversion solution and the purified pure water to the film forming means . The return pipe is composed of an overflow pipe that connects a pure water tank that stores pure water and a film forming treatment tank that stores a chemical conversion treatment liquid,
  After the excess chemical conversion liquid adhering to the object to be processed and the pure water after washing are collected in the pure water tank, the supernatant portion (including the chemical conversion liquid) overflowed in the pure water tank is subjected to the film formation process. The coating pretreatment device according to claim 5, wherein the coating pretreatment device is configured to be returned to the tank. Pure water replenishing means for replenishing the pure water cleaning means with a shortage of pure water;
The coating pretreatment apparatus according to claim 5 or 6 , further comprising a treatment liquid replenishing means for replenishing the film forming means with a shortage of chemical conversion treatment liquid . The coating according to any one of claims 5 to 7 , wherein the pure water cleaning means device and the electrodeposition coating device are continuously installed without providing a storage device for the object to be processed. Pre-processing device.

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