JP2006181503A - Treatment method and apparatus for coating-booth circulation water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treatment method for coating-booth circulation water capable of easily separating and extracting a coating component from a coating-collecting circulation water even in a coating booth using a water-based coating. <P>SOLUTION: The treatment method of coating-booth circulation water has a step for adding an alkaline solution to coating-booth circulation water of the coating booth 1, a step for filtering circulation water to which the alkaline solution is added to separate a filtrate from the residue, a step for neutralizing the filtrate and a step for reusing a neutralized filtrate as the coating-collecting circulation water. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and a processing apparatus for processing paint booth circulating water.

  In a painting booth that performs spray painting with a painting gun such as intermediate coating or top coating, a processing device is provided for collecting and processing oversprayed paint. In the conventional processing apparatus, a pit is provided under the slats of the painting booth floor, and water is continuously flowed from both sides of the booth, thereby collecting the oversprayed paint in the pit (see FIG. 3 of Patent Document 1).

  By the way, when collecting oversprayed paint by circulating paint collecting water, when the paint is an organic solvent-based paint, the paint is dispersed in the circulating water using a surfactant as a dispersant or a settling agent. Or, it is collected by settling, and the paint is separated and extracted from the circulating water, and then clean water is reused as the circulating water. However, the organic solvent does not dissolve in water, so the separation and extraction process should be relatively easy. Can do.

  However, since water-based paints that are frequently used recently are dissolved in circulating water, it is difficult to separate and extract paint components when recycling water is used, compared to organic solvent-based paints.

For example, if an ultrafiltration device (UF: a device that separates paint components with a reverse osmosis membrane by applying a high pressure) that is also widely used in an electrodeposition paint regeneration device, the paint components can be separated and extracted from the circulating water. Although it is possible (see, for example, Patent Document 2), the ultrafiltration device is disadvantageous in that it is expensive and the running cost is high. When used in an electrodeposition paint recycling device, the electrodeposition paint can be regenerated because the same electrodeposition paint, which compensates for the increase in running costs. Therefore, it is practically difficult to regenerate the paint, and only the circulating water can be regenerated. There is a similar reason for an intermediate coating booth that uses a multicolor intermediate coating. Therefore, it was unrealistic to use the ultrafiltration device for the regeneration process of the painting booth.
JP 2000-93860 A JP-A-6-55134

An object of the present invention is to provide a processing method and apparatus for painting booth circulating water that can easily separate and extract coating components from circulating water for collecting paint even in a painting booth that uses water-based paint. .
In order to achieve the above object, the method for treating circulating water in a painting booth according to the present invention includes a step of adding an alkaline solution to circulating water for collecting paint in a painting booth, and filtering the circulating water to which the alkaline solution has been added. And separating the filtrate into a residue, neutralizing the filtrate, and reusing the neutralized filtrate as paint collection circulating water.

  In order to achieve the above object, the coating booth circulating water treatment apparatus of the present invention comprises means for adding an alkaline solution to the coating booth for collecting paint in the coating booth, and circulating water to which the alkaline solution is added. It has a means to filter and isolate | separate into a filtrate and a residue, A means to neutralize the said filtrate, A means to return the said neutralized filtrate to a coating booth, It is characterized by the above-mentioned.

  Gelation occurs when an alkaline solution such as alkaline electrolyzed water is added to an aqueous paint containing water as a solvent. This is because water-based paints have acidic polar groups such as carboxylic acid in order to disperse the resin component in water as a solvent, but when an alkaline solution is added thereto, the resin particles that have been dispersed so far swell ( This is because it gels. In the present invention, utilizing this, an alkaline solution is added to circulating water for collecting paint. Thereby, since a coating component gelatinizes in circulating water, it can isolate | separate into a coating component and a water component easily by the following filtration process. The paint component that has been filtered to form a residue is discarded after concentration / drying, but the filtered filtrate is water that does not contain the paint component. Can be reused.

  According to the present invention, a paint component and water can be separated using a simple and inexpensive filtration device, not an expensive filtration device such as an ultrafiltration device, and water can be regenerated.

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 cross-sectional view showing a coating booth according to the present embodiment, which can be applied to both an intermediate coating booth and a top coating booth. In particular, when applied to a painting booth using a water-based paint, the effect of the present invention is more exhibited.

  As shown in the figure, the painting booth 1 according to the present embodiment is composed of a panel 11 formed in a tunnel shape and a pit 12, a ceiling filter is provided on the ceiling surface 13 inside thereof, and a floor surface 14. There is a child of the fox. A painting chamber 15 is formed between the ceiling surface 13 provided with the ceiling filter and the floor surface 14 provided with the ridge.

    An air supply duct for guiding conditioned air from the air supply device and a rectifying chamber 16 are provided between the ceiling surface 13 and the ceiling of the panel, and the conditioned air rectified in the rectifying chamber 16 has a ceiling filter. It passes through and is blown downward into the painting chamber 15.

    The pit 12 under the spider on the floor 14 is used as a collection chamber 17 for oversprayed paint (spatter paint). When the water overflowing from the spear 18 flows through the collection plate 19, this spatter paint is used. After supplementing and collecting in the pit 12, it is sent to the circulating water treatment apparatus according to the present invention. These troughs 18 and collecting plates 19 are provided over the entire length of the painting booth 1, and when the object to be coated is carried into the painting booth 1, the circulating water always overflows from the trough 18 and the collecting plates 19. It is flowing. Although not shown in the figure, the collection chamber 17 is provided with an exhaust device, and the conditioned air that has flowed into the collection chamber 17 after passing through the coating chamber 15 is recovered to the outside of the system. Exhausted.

  B indicated by a two-dot chain line in the figure is an automobile body that is an object to be coated, and is transported at a constant speed in a painting booth by a floor conveyor provided on the floor 14 while being mounted on a painting carriage. .

  The circulating water treatment device 2 according to this embodiment includes a first tank 21 to which circulating water containing overspray paint collected in the collection chamber 17 of the painting booth 1 is guided, and the first tank 21. The alkaline solution addition device 22 for adding the alkaline solution, the filtration device 23 for filtering the paint-containing circulating water to which the alkaline solution has been added in the first tank 21, and the filtrate separated by the filtration device 23 are guided. A second tank 24, a neutralizer addition device 25 for adding a neutralizer to the second tank 24, and a pipe for returning the filtrate neutralized in the second tank 24 to the basket 18 of the painting booth 1. 26 and a pump 27.

  The paint-containing circulating water collected in the collection chamber 17 of the painting booth 1 is sent to the first tank 21 regularly or continuously using, for example, a pump. When the paint to be applied is not only a water-based paint but also an organic solvent-based paint, a surfactant as a dispersant or a settling agent in the collection chamber 17 of the painting booth 1 or in the first tank 21. It is desirable to prevent the paint component and the solvent component of the organic solvent-based paint from aggregating in the circulating water.

  The alkaline solution addition device 22 adds an alkaline solution to the paint-containing circulating water guided to the first tank 21, and an alkaline solution corresponding to the amount of the paint-containing circulating water flowing into the first tank 21. Supply. As a result, the paint component (resin component) of the water-based paint contained in the circulating water is gelled. That is, when an alkaline solution is added to the first tank 21, an acidic polar group, for example, a carboxyl group COOH contained in a water-based paint dissolved in circulating water is combined with the alkaline solution, thereby losing the polarity. The dispersed coating resin component swells and gels as a result.

  Although it does not specifically limit as an alkaline solution, The aqueous solution containing ammonium hydroxide or an organic base, alkaline electrolyzed water, such as sodium hydroxide, can be illustrated. In particular, alkaline electrolyzed water is most preferable as the alkaline aqueous solution according to the present example from the viewpoint of recycling the circulating water because it does not contain chemical substances. When alkaline electrolyzed water is used for the alkaline solution, acidic electrolyzed water generated simultaneously with the electrolysis of water can be used as a neutralizing agent described later, pH adjustment is unnecessary, and acidic electrolyzed water is discarded. There is nothing.

  Moreover, it is preferable that the pH of the alkaline solution added here is 8-12. When the pH is less than 8, the effect of the present invention is small, and when the pH exceeds 12, the use amount and cost of the neutralizing agent may increase.

  The circulating water to which the alkaline solution is added in the first tank 21 is sent to the filtration device 23, where it is separated into a filtrate and a residue. The filtration device 23 of this example is a filtration device using a cloth filter or a coarse stainless mesh filter having a mesh size of about 20 to 100, and is dispersed or settled with a water-based paint component gelled by this filter and a surfactant. The organic solvent-based paint component is separated as a residue.

  The separated residue is difficult to regenerate as a paint because various pigments are randomly mixed. Therefore, the aggregated residue is concentrated and dried, and then discarded.

  The filtrate that has passed through the filtration device 23 contains almost no water-based paint component and no organic solvent-based paint component, but has become a medium to strong alkaline solution having a pH of 8 to 11 by adding an alkaline solution. If this is reused as circulating water in the painting booth 1 as it is, there is a problem that paint components are deposited in the collection chamber 17 and the removal operation becomes difficult. Then, the neutralizer is added by the neutralizer addition device 25 for neutralization. The neutralizing agent is not particularly limited, and a strong acid such as hydrochloric acid or sulfuric acid can be used. However, as described above, the use of acidic electrolyzed water significantly increases safety and wastewater treatment. The neutralization in the second tank 24 is not a strict meaning neutralization, but may be such that the pH is adjusted to around 7 within a range in which the above-described problem does not occur.

  The filtrate neutralized in the second tank 24 is sucked by the pump 27 and returned to the basket 18 of the painting booth 1 through the pipe 26.

  As described above, according to the circulating water treatment method and treatment apparatus according to the present embodiment, the water-based paint component dissolved in the circulating water can be separated by using only a simple filtration device such as a cloth filter or a stainless steel filter. The circulating water as the filtrate can be reused. In particular, when alkaline electrolyzed water is used as the alkaline solution and acidic electrolyzed water is used as the neutralizing agent, the safety in handling is remarkably improved, and since it returns to normal water over time, there is no need for post-treatment. .

  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 sectional drawing which shows an example which applied the processing apparatus for circulating water which concerns on embodiment of this invention to the painting booth.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Painting booth 11 ... Panel 12 ... Pit 13 ... Ceiling surface 14 ... Floor 15 ... Painting room 16 ... Rectification room 17 ... Collection room 18 ... Trap 19 ... Collection board 2 ... Circulating water processing apparatus 21 ... 1st Tank 22 ... Alkaline solution addition device 23 ... Filtration device 24 ... Second tank 25 ... Neutralizer addition device 26 ... Pipe 27 ... Pump

Claims (10)

Adding an alkaline solution to circulating water for collecting paint in a paint booth; filtering the circulating water to which the alkaline solution has been added; separating the filtrate and residue; neutralizing the filtrate; and And recycling the neutralized filtrate as paint collecting circulating water. 2. The coating booth circulating water treatment method according to claim 1, wherein the alkaline solution contains alkaline electrolyzed water as a main component. The method of treating painting booth circulating water according to claim 1 or 2, wherein the alkaline solution has a pH of 8 to 12. 4. The method for treating circulating water in a coating booth according to claim 2, wherein a neutralizing agent mainly composed of acidic electrolyzed water is used in the step of neutralizing the filtrate. The said residue is a disposal process after a concentration process and / or a drying process, The processing method of the coating booth circulating water in any one of Claims 1-4 characterized by the above-mentioned. Means for adding an alkaline solution to circulating water for collecting paint in a paint booth; means for filtering the circulating water to which the alkaline solution has been added to separate it into a filtrate and residue; means for neutralizing the filtrate; Means for returning the neutralized filtrate to the paint booth, and a paint booth circulating water treatment device. The coating booth circulating water treatment apparatus according to claim 6, wherein the alkaline solution contains alkaline electrolyzed water as a main component. 8. The coating booth circulating water treatment apparatus according to claim 6 or 7, wherein the pH of the alkaline solution is 8-12. 9. The processing apparatus for circulating paint booth water according to claim 7 or 8, wherein the means for neutralizing the filtrate uses a neutralizing agent mainly composed of acidic electrolyzed water. The processing apparatus for circulating the coating booth according to any one of claims 6 to 9, further comprising means for concentrating and / or drying the residue.

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