JP2014155916A - Method of treating wet coating booth circulating water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method which enables sufficient floatation separation of coating ingredients from wet coating booth circulating water by preventing deterioration of the effect of floating the coating ingredients in the wet coating booth circulating water.SOLUTION: A method of treating wet coating booth circulating water includes a step of adding a cationic agent and an anionic agent to the wet coating booth circulating water and a step of floatation-separating coating ingredients from the coating booth circulating water containing the cationic and anionic agents. The cationic and anionic agents are added to the wet coating booth circulating water in such a way as to give a charge amount of the wet coating booth circulating water of -5 to -200 μeq/L in the floatation separation of the coating ingredients.

Description

  The present invention relates to a method for treating circulating water in a wet paint booth.

  Various paints are spray-painted in the painting process of the automobile industry, home appliances, metal product manufacturing industries, and the like. Industrially used paints are roughly classified into solvent-based paints and water-based paints, and each paint is used alone or in combination. The surplus paint at that time is usually washed with water and then separated from the water and processed. In order to separate the surplus paint and water, a chemical is added to the water containing the surplus paint, and the paint components become non-tacky or agglomerate (Patent Documents 1 and 2).

  The water used for washing the excess paint is stored in a circulating water pit, a chemical is added, and the paint components are separated or floated in the water to be separated and used as wet paint booth circulating water.

  Since the wet paint booth circulating water has different tackiness, cohesiveness, foaming property, etc. depending on the type, properties or amount of paint components contained therein, it has been difficult to control the amount of chemicals to be added.

  In Patent Document 3, a cationic flocculant is added to the wet paint booth circulating water, and in Patent Document 4, a cationic coagulant and an amino resin acid colloid are added to the wet paint booth circulating water, and the charge amount of the solution is generally reduced. The wet paint booth circulating water is treated by controlling the positive value (cation side) to make the paint components of the water-based paint and the solvent-type paint non-tacky and aggregate.

JP 2004-337671 A JP 2006-247456 A JP 2002-79263 A JP 2006-61776 A

  Usually, since the wet paint booth circulating water contains an anionic surfactant derived from a paint, bubbles are easily generated, and the surface of the foam is covered with an anionic functional group. As in Patent Documents 3 and 4, when the wet coating booth circulating water is treated on the cation side with the charge amount, the surface of the foam is electrically neutralized, and bubbles in the water and foam on the water surface are electrically defoamed. . As a result, the floating effect of the paint component is reduced, and there is a problem that the paint component is not sufficiently levitated and separated from the wet paint booth circulating water.

  It is an object of the present invention to provide a method capable of sufficiently floating and separating paint components from circulating water in a wet paint booth.

  The inventors of the present invention add a cationic agent and an anionic agent to the wet painting booth circulating water, and make the charge amount of the wet painting booth circulating water within a predetermined range, so that paint components in water can be easily floated and separated. As a result, the present invention has been completed.

  Specifically, the present invention provides the following methods.

(1) Wet paint booth circulating water treatment method,
Adding a cationic agent and an anionic agent to the wet paint booth circulating water;
And a step of levitating and separating the paint component from the wet paint booth circulating water containing the cationic agent and the anionic agent,
The method in which the charge amount of the wet coating booth circulating water when the coating component floats and separates is −5 μeq / L to −200 μeq / L.

  (2) The method according to (1), wherein the anionic drug is added downstream from the cationic drug.

(3) The cationic agent is added upstream from the location where the paint is discharged into the wet paint booth circulating water,
The said anionic chemical | medical agent is a method as described in (1) or (2) added downstream from the location where a coating material is discharged | emitted by the said wet coating booth circulating water.

  According to the present invention, the paint component can be sufficiently levitated and separated from the wet paint booth circulating water.

It is a schematic block diagram which shows an example of the wet painting booth circulation system with which the method of this invention is applied.

  The present invention relates to a wet paint booth circulating water treatment method comprising adding a cationic agent and an anionic agent to the wet paint booth circulating water, and a wet coating booth circulating water containing the cationic agent and anionic agent. And the step of levitating and separating the paint component from the surface, and the charge amount of the wet paint booth circulating water when the paint component is levitated and separated is -5 μeq / L to −200 μeq / L.

  Hereinafter, although an embodiment of the present invention is described using a drawing, the present invention is not restricted by this.

  The wet painting booth circulation system 1 of the present invention has a painting booth 10, a circulating water pit 20, and a solid-liquid separator 30, and between the painting booth 10 and the circulating water pit 20, the circulating water pit 20 to the painting booth 10. A pipe 41 through which circulating water (upstream) A flows through and a pipe 42 through which circulating water (downstream) B returns from the coating booth 10 to the circulating water pit 20. The paint component separated from the paint component by the pipe 43 and the solid-liquid separator 30 through which the paint component-containing water D floated and separated in the circulating water pit 20 passes between the circulating water pit 20 and the solid-liquid separator 30. A pipe 44 through which the separation water E passes is provided. Then, the water from which the paint component has been separated is led out again to the pipe 41 and reused.

  In the wet paint booth circulating water, the paint component is reduced or removed in the circulating water pit 20, the pump 21 is sent as circulating water (upstream) A to the pipe 41, and the excess paint discharged in the painting booth 10 is collected. It passes through the pipe 42 and returns to the circulating water pit 20 as circulating water (downstream) B. Also, the paint component-containing water D floating and separated in the circulating water pit 20 is conveyed to the solid-liquid separator 30 through the pipe 43, and the paint component separation water E separated from the paint component is circulated through the pipe 44. Return to water pit 20.

  Since the wet coating booth circulating water dissolves the surfactant contained in the paint, it easily foams on the surface of the stored water C in the circulating water pit 20. In order to suppress excessive foaming, the circulating water pit 20 may have a foam extinguishing shower 22 at the top thereof. Foamed shower water may be industrial water, groundwater, or the like, or may be wet paint booth circulating water. Since the wet paint booth circulating water can be used effectively, the wet paint booth circulating water is preferable.

  In the present invention, the upstream refers to the opposite side of the circulating water flow direction in the circulation path starting from the outlet of the circulating water pit 20 and ending at the inlet of the circulating water pit 20, and the downstream refers to the flowing direction of the circulating water. Means the side along.

  The surplus paint collected at the coating booth 10 is floated and separated by circulating water pits 20 by precipitation or bubbles in the circulating water, and is transported to the solid-liquid separator 30 together with the circulating water. Then, it is concentrated to form a concentrated bowl 31 and discarded. When the paint component is floated and separated, a pressure floating device can be used.

  The painting booth 10 is a booth for painting an object to be coated with a paint, and is not particularly limited. For example, the painting booth 10 is a booth used in a painting process in the automobile industry, home appliances, metal product manufacturing industries, and the like. In the painting booth, for example, a surplus paint or the like of the paint sprayed on the object is generated by spraying or the like, and dissolved or precipitated in the circulating water in the wet painting booth.

  The paint used for painting is not particularly limited, but includes at least one water-based paint or solvent-type paint. There are no particular restrictions on the type or amount of the water-based paint or solvent-type paint.

  In the treatment of wet paint booth circulating water, both cationic and anionic drugs are added. By adding both a cationic drug and an anionic drug, and setting the charge amount of the stored water C in the circulating water pit 20 to -5 μeq / L to −200 μeq / L, paint components from the wet paint booth circulating water Can be levitated and separated efficiently. The charge amount is more preferably −10 μeq / L or less.

  When the charge amount of the stored water C is larger than −5 μeq / L, it is difficult to float and separate the paint component from the wet paint booth circulating water, and the surface of the wet paint booth circulating water is likely to foam. When the charge amount of the stored water C is smaller than −200 μeq / L, the adhesiveness of the coating component becomes strong, and the surface of the wet coating booth circulating water easily foams excessively. On the other hand, when the charge amount of the stored water C is in the range of −5 μeq / L to −200 μeq / L, the paint component is easily levitated and separated. The charge amount of the stored water C is preferably −50 μeq / L to −200 μeq / L.

  The cationic drug is not particularly limited as long as it is a compound that can act as a cation with respect to the coating component, but it is one or more of a cationic inorganic drug or a cationic organic drug. The cationic inorganic agent is at least one selected from, for example, sulfate band, polyaluminum chloride, basic aluminum chloride, aluminum nitrate and the like. The cationic organic agent is at least one selected from, for example, dimethyldiallylammonium chloride, alkylamine / epichlorohydrin condensate, polyethyleneimine, DMA, DADMAC and the like.

  The anionic drug is not particularly limited as long as it is a compound that can act as an anion for the coating component, but it is one or more of an anionic inorganic drug or anionic organic drug. The anionic inorganic agent is at least one selected from, for example, clay, bentonite, sepiolite, hectorite, sodium aluminate and the like. An anionic organic chemical | medical agent is one or more selected from a novolak type phenol resin, a resole type phenol resin, etc., for example. Since the novolac type phenol resin is sparingly water-soluble, it may be added as an alkaline aqueous solution such as caustic soda.

  The addition amount of the cationic agent is not particularly limited, but if it is too small, the adhesiveness of the coating component becomes strong, and the coating component becomes difficult to float and separate. For example, the wet coating booth circulating water is 1% by mass or more, preferably 1.5 mass% or more can be added. If the amount of the cationic agent added is excessive, the amount of charge increases to a positive value, and foaming from the surface of the wet paint booth circulating water becomes intense, making it difficult for the paint components to float and separate. For example, 10% by mass or less of the wet paint booth circulating water can be added, but it does not prevent the amount from exceeding 10% by mass. In addition, the addition amount of the cationic chemical | medical agent in piping can be determined based on the flow volume of wet coating booth circulating water.

  Moreover, since the floating effect of the paint component can be improved and foaming from the surface of the wet paint booth circulating water can be suppressed, the amount of the anionic drug can be selected based on the charge amount of the stored water C, and is not particularly limited. The wet coating booth circulating water may be 8 mass% or more, 10 mass% or more, 12 mass% or more, 15 mass% or more, and may be 30 mass% or less.

  The place where the cationic agent is added is, for example, circulating water (upstream) A upstream from the place where the paint is discharged to the wet painting booth circulating water or circulating water downstream from the place where the paint is discharged to the wet painting booth circulating water. It may be (downstream) B. It is preferable to add a cationic agent upstream from the painting booth because it is possible to suppress the surplus paint discharged at the painting booth 10 from aggregating and adhering to the equipment.

  The location where the anionic drug is added is not particularly limited, but may be the same location as the addition location of the cationic drug, or may be downstream from the location where the cationic drug is added. Since the addition amount of the anionic drug can be adjusted based on the charge amount of the wet circulation booth circulating water after the addition of the cationic drug, the place where the anionic drug is added is preferably downstream from the place where the cationic drug is added. . For example, circulating water (upstream) A upstream from the location where paint is discharged to the wet paint booth circulating water, circulating water (downstream) B downstream from the location where paint is discharged to the wet coating booth circulating water, or in the circulating water pit Stored water C. Non-adhesiveness, cohesiveness, foamability, etc. differ depending on the type, nature or amount of the paint component, and the cationic agent may become excessive in the wet paint booth circulating water. Since it can respond to such a case, it is preferable that the place which adds an anionic chemical | medical agent is downstream from the location where a coating material is discharged | emitted by wet coating booth circulating water, or the stored water C.

  When a cationic agent is added to circulating water (upstream) A introduced into the painting booth, the charge amount of the circulating water is preferably 0 to −50 μeq / L. The charge amount of the circulating water (upstream) A is within the range, so that it is possible to promote the detackification of the excess paint in the painting booth 10 and it becomes easy to clean the paint components. It is possible to suppress the foaming of the wet coating booth circulating water in a large amount and the adhesion of the paint components.

  The amount of charge in the wet paint booth circulating water can be measured before and after the addition of the cationic drug or before and after the addition of the anionic drug. It is preferable to measure the amount of wet paint booth circulating water before and after the addition of the cationic drug and before and after the addition of the anionic drug from the viewpoint of adjusting the amount of each drug. It may be measured both after the addition. Although it is not particularly limited, by measuring the charge amount of the circulating water in the wet circulation booth, it can be used to determine the excess or deficiency of both the cationic drug and the anionic drug used, and foaming and levitation generated in the wet painting booth circulation system 1 It is possible to effectively cope with a separation failure. For example, if the amount of charge is positive after the addition of the cationic agent, it can be seen that the cationic agent is excessive, the amount of the cationic agent added is reduced, or the amount of the anionic agent is increased to increase the wet paint booth circulating water. The amount of charge can be adjusted. Note that the addition amount of the drug may be automatically controlled based on the measured value of the charge amount. The amount of charge in the wet paint booth circulating water can be measured using a particle charge meter such as a PCD device.

  The present invention was carried out using the following chemicals or paints.

(Cationic drug)
As a cationic drug, Zeta Ace (alkylamine / epichlorohydrin condensate, manufactured by Kurita Kogyo Co., Ltd.) was used.

(Anionic drug)
A phenolic resin solution was used as an anionic drug. The phenolic resin solution was prepared by taking 10 g of caustic soda and 170 g of pure water in a beaker and adding 20 g of Residtop PSM 4324 (Novolac type phenol resin, manufactured by Gunei Chemical Industry Co., Ltd.) while stirring the water.

(paint)
GWP2000 (manufactured by Nippon Paint Co., Ltd.) was used as the water-based paint, and OG12K (manufactured by Nippon Paint Co., Ltd.) was used as the solvent-type paint.

(Examples 1-11, Comparative Examples 1-14)
Using a test apparatus with a retained water volume of 50 L, the circulating water volume was tested at 50 L / min. 10 minutes each of paint (water paint, solvent paint, mixture of water paint and solvent paint) in circulating water for 20 minutes at 10 g / min (in the case of a mixture, water paint and solvent paint at the same time, 5 g / min each) Sprayed and sprayed. A predetermined amount of a cationic drug and an anionic drug were continuously added to the water tank of the testing machine. Thereafter, the circulating water containing the paint, the cationic agent and the anionic agent was transferred to a 1 liter cylinder and shaken up and down 50 times. Each of the paint components was evaluated and judged for non-adhesive performance, floating performance and anti-foaming performance of stored water. Moreover, the charge amount of circulating water was measured using PCD-04 (made by a mutec). Tables 2 to 4 show the evaluation / determination of the non-adhesive performance, the floating performance, the anti-foaming performance, and the charge amount for each paint.

  The evaluation / determination of the non-adhesive performance, the floating performance and the anti-foaming performance is based on the criteria shown in Table 1.

  From Examples 1 to 11 and Comparative Examples 1 to 14, the charge amount of the wet paint booth circulating water is in the range of −5 μeq / L to −200 μeq / L using both the cationic drug and the anionic drug. Thus, it was found that the floatation separation performance of the paint components and the treatment effect of the wet paint booth circulating water can be obtained.

  Further, from Example 6, Comparative Examples 2, 11 and the like, it was found that the solvent-type paint has a higher charge amount than the water-based paint and the mixed paint. Therefore, it can be said that the treatment of the wet paint booth circulating water is preferably performed on the basis of the charge amount of the wet paint booth circulating water rather than on the basis of only the amount of the cationic agent and the anionic agent to be added.

DESCRIPTION OF SYMBOLS 1 Wet paint booth circulation system 10 Paint booth 11 Water film board 20 Circulating water pit 21 Pump 22 Foam extinguishing shower 30 Solid-liquid separator 31 Concentration tank 41, 42, 43, 44 Piping 60 Fan 61 Filter A Circulating water (upstream)
B Circulating water (downstream)
C Storage water D Paint component-containing water E Paint component separation water

Claims (3)

A wet painting booth circulating water treatment method,
Adding a cationic agent and an anionic agent to the wet paint booth circulating water;
And a step of levitating and separating the paint component from the wet paint booth circulating water containing the cationic agent and the anionic agent,
The method in which the charge amount of the wet coating booth circulating water when the coating component floats and separates is −5 μeq / L to −200 μeq / L.   The method of claim 1, wherein the anionic drug is added downstream from the cationic drug. The cationic drug is added upstream from the location where the paint is discharged into the wet paint booth circulating water,
The method according to claim 1 or 2, wherein the anionic agent is added downstream from a portion where the paint is discharged into the wet paint booth circulating water.

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