Circulation water treatment agent for wet coating booth and method of use of the same

Abstract

To provide a circulation water treatment agent for a wet coating booth and a method of use of the same that can flocculate, separate, and recover coating mist more efficiently, reduce burden on an operator with a prolonged use period of circulation water, and reduce load on an environment.SOLUTION: A circulation water treatment agent includes: an aluminum chloride as a principal component; 20-25% of alumina; and 0.5-1% of a defoaming agent. The circulation water treatment agent is loaded into circulation water 20 for a wet coating booth 10, an alkali agent containing calcium hydroxide as a principal component is mixed thereto, pH of the circulation water 20 is adjusted to 8-10, and then the circulation water 20 for the wet coating booth 10 is circulated.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a circulating water treatment agent for aggregating paint mist adsorbed in circulating water used in a wet paint booth, and a method for using the same. [Background technology]

[0002] For example, various paints are used for spray painting in the painting process of products such as automobiles, household electrical appliances, and metal products. Industrially used paints are generally divided into solvent-based paints and water-based paints, which are used alone or in combination. Water-based paints are broadly divided into three types: water-soluble, dispersion, and emulsion. Because all of these types use water as the solvent, they are non-flammable, safe, and hygienic, and do not pose a risk of pollution caused by solvents. As a result, their range of applications has been expanding in recent years.

[0003] In the coating process for various industrial products, the yield of paint sprayed onto the object to be coated is generally around 60-80%, with 40-20% of the paint used remaining as excess paint.To prevent the excess sprayed paint mist from leaking outside, it is absorbed into a water stream in the wet coating booth where various industrial products are coated, and the water that has absorbed the paint is recycled and reused.

[0004] Conventionally, treatment chemicals have been added to the circulating water used in wet painting booths to coagulate and separate excess paint in the circulating water. For example, organic and inorganic chemicals have been used as treatment chemicals to treat paint mist that has become mixed into the circulating water in wet painting booths, as described in Patent Documents 1 and 2.

[0005] Additionally, Patent Document 3 discloses the combined use of a phenolic resin and a cationic polymer as a treatment agent for efficiently flocculating paint in the circulating water of a wet painting booth, including water-based or solvent-based paint. The treatment agent disclosed in Patent Document 3 involves dissolving the phenolic resin in an alkaline aqueous solution or the like and injecting it into the circulating water of a wet painting booth. The phenolic resin dissolves or disperses in a colloidal state, and in the presence of the cationic polymer, the charge of the phenolic resin is neutralized, causing it to coagulate and become insolubilized. The paint dissolved or dispersed in a colloidal state in the circulating water is also coagulated and insolubilized by the cationic polymer, causing its charge to be neutralized. When the phenolic resin is insolubilized by the cationic polymer, it flocculates and coagulates, entraining the coagulated paint. The phenolic resin flocs that coagulate and entrain the paint form particles of a certain size, making them easily separated and removed from the circulating water by methods such as floatation, centrifugation, and filtration. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-71434 [Patent Document 2] Japanese Patent Application Publication No. 11-77061 [Patent Document 3] Japanese Patent Application Publication No. 2019-202281 Summary of the Invention [Problem to be solved by the invention]

[0007] The organic agents disclosed in Patent Documents 1 and 3 have the problem that the paint sludge, which is an aggregate of paint mist that uses the agent as a glue, is enveloped in a resin polymer, resulting in a high moisture content in the recovered paint sludge and making dehydration difficult. On the other hand, the inorganic agents disclosed in Patent Document 2 have the problem that the insoluble fine particles they produce have weak coagulation strength, resulting in a slow growth rate of the paint sludge, which is an aggregate of insoluble fine particles that has absorbed the paint mist, making it difficult to recover the paint sludge quickly. Furthermore, inorganic coagulants are weakly acidic (pH about 4), and this acidity can easily corrode equipment such as piping.

[0008] Furthermore, these conventional coagulants have problems such as a foul odor when used in circulating water for a long period of time, paint residue solidifying, and clogging the suction part of the piping, so that temporary measures such as adding deodorants or dispersants have been taken to deal with these problems, and relatively frequent replacement and cleaning of the circulating water has been required. Therefore, if the amount of painting work is large, the frequency of this cleaning and replacement also increases, which further burdens the workers.

[0009] The present invention has been made in view of the above-mentioned conventional background art, and aims to provide a circulating water treatment agent for a wet paint booth that can more efficiently aggregate, separate and recover paint mist, extend the service life of the circulating water, reduce the burden on workers, and place a low burden on the environment, as well as a method of using the same. [Means for solving the problem]

[0010] This invention relates to a circulating water treatment agent for wet paint booths, which is used by adding it to the circulating water in the booths where products are painted. The circulating water treatment agent for wet paint booths is mainly composed of a basic aluminum chloride copolymer, contains 20 to 25% alumina, and contains 0.1 to 1% of an antifoaming agent. Activated carbon may also be added in an amount of 0.5 to 1%.

[0011] The present invention also relates to a method for using a circulating water treatment agent that is added to the circulating water of a wet paint booth in which products are painted, in which 0.1 to 0.5% of a circulating water treatment agent containing aluminum chloride as its main component, 20 to 25% alumina, and 0.5 to 1% of an antifoaming agent is added to the circulating water of the wet paint booth, and an alkaline agent containing calcium hydroxide as its main component is further mixed in to adjust the pH of the circulating water to 8 to 10, and the circulating water of the wet paint booth is circulated, so that excess paint during painting falls into and is adsorbed by the circulating water, and the paint components in the circulating water are coagulated by the circulating water treatment agent.

[0012] The paint components in the circulating water are aggregated to separate the paint components from the water component, and the water component is reused.Furthermore, the paint components separated from the water component by aggregation may be recovered and dehydrated so that they can be used as fuel. [Effects of the Invention]

[0013] The circulating water treatment agent of the present invention and its method of use can more efficiently aggregate, separate and recover paint mist, extend the usable life of the circulating water, and reduce the burden on workers. Furthermore, the usable life of circulating water from which paint components have been efficiently aggregated and separated can be extended, and a treatment method with less impact on the environment can be provided. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic cross-sectional view of a paint booth according to an embodiment of the present invention. [Figure 2] 3 is a photograph showing the state of circulating water before and after treatment with a circulating water treating agent according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] A circulating water treatment agent according to one embodiment of the present invention and its method of use will be described below with reference to the drawings. First, a wet paint booth where painting is performed will be described with reference to Figure 1. The wet paint booth 10 of this embodiment is a work area where paint is applied to the surfaces of various products 12, and is a device that absorbs excess paint during painting into circulating water 20 and collects it. This wet paint booth 10 has an application area 10a where paint 16 sprayed from a sprayer 14 is applied to the products 12, and an absorption area 10b where unapplied paint 16 is absorbed into the circulating water 20.

[0016] A circulating water tank 22 through which circulating water 20 flows is provided below the application area 10a and the suction area 10b, and is provided so that paint 16 not used for application can fall onto the surface of the circulating water 20 and be collected. An exhaust device 26 equipped with a blower motor 24 is provided above the suction area 10b, and an exhaust blower (not shown) is provided within the exhaust device 26.

[0017] Below the exhaust device 26 in the adsorption area 10b, multiple drain plates 28 for the circulating water 20 are attached in the space between the exhaust device 26 and the circulating water tank 22. The multiple drain plates 28 located at the top are tilted downward and staggered so that droplets of the circulating water 20 sucked up by the exhaust device 26 fall into the circulating water tank 22. On the underside of the lower drain plates 28, there is a water flow path 30 that is provided so that the circulating water 20 is blown up from the surface of the circulating water tank 22 located on the coating area 10a side. As a result, the air in which the excess paint 16 is suspended and the circulating water 20 effectively come into contact with the adsorption area 10b, and the circulating water 20 is sucked from the coating area 10a to the adsorption area 10b, and the excess paint 16 is efficiently adsorbed by the circulating water 20.

[0018] Next, a circulating water treatment agent according to an embodiment of the present invention will be described. The circulating water treatment agent is a circulating water treatment agent that is mainly composed of polyaluminum chloride, which is a copolymer of basic aluminum chloride, and contains 20 to 25% alumina, and serves as a flocculant.

[0019] Furthermore, this circulating water treatment agent contains 0.1 to 1%, preferably 0.5 to 1%, of an antifoaming agent. The antifoaming agent is a solvent-based metal soap antifoaming agent, for example, composed of 80% mineral oil and 20% surfactant or the like.

[0020] It is also advisable to add 0.5 to 1% activated carbon. Activated carbon has deodorizing properties, as well as the functions of reducing BOD (biochemical oxygen demand) and normal hexane, and prevents the generation of bad odors in the paint booth 10. Table 1 shows the results of measurements of the BOD (biochemical oxygen demand) reduction function and normal hexane reduction function. [Table 1]

[0021] Next, a method for using the circulating water treating agent according to an embodiment of the present invention will be described. The circulating water treating agent according to this embodiment is used by adding 0.1 to 0.5% of the circulating water treating agent, which is primarily composed of a copolymer of basic aluminum chloride and to which 0.1 to 1% of an antifoaming agent has been added, to the circulating water 20 in the wet painting booth 10. Furthermore, an alkaline agent primarily composed of calcium hydroxide is mixed with the circulating water 20 to adjust the pH of the circulating water 20 to 8 to 10.

[0022] After this, the circulating water 20 in the wet coating booth 10 is circulated by a pump or the like (not shown). After the circulation of the circulating water 20 has begun, the sprayer 14 begins painting the product 12. During painting, air flows from the coating area 10a toward the suction area 10b due to the exhaust action of the exhaust device 26, and excess paint 16 that has been sprayed into the coating area 10a without adhering to the product 12 is sucked toward the suction area and falls onto the surface of the circulating water 20. The paint 16 that has flowed from the coating area 10a toward the suction area 10b and the excess paint 16 that has fallen onto the circulating water 20 are adsorbed as they circulate and mixed into the circulating water 20.

[0023] The circulating water 20 containing the circulating water treatment agent adsorbs the excess paint 16, and the paint components mixed in the circulating water 20 aggregate during and after circulation in a stationary state, and are separated from the water. The circulating water 20 into which the paint 16 has been adsorbed and mixed is cloudy as shown in Figure 2(a) before the circulating water treatment agent is added, but by adding the circulating water treatment agent, the paint components in the circulating water 20 aggregate, and as shown in Figure 2(b), aggregated components 20a in which the paint 16 has adhered to the circulating water treatment agent, which is a coagulant, settle and separate in the water.

[0024] After the paint components in the circulating water 20 are coagulated and the water component and the paint component are separated, the water component in the circulating water 20 can be reused as the circulating water 20 in the painting booth 10.

[0025] Furthermore, the paint components that have been aggregated and separated from the water component and the activated carbon in the circulating water treatment agent are organic substances, and can be recovered as solids, dehydrated, and used as fuel.

[0026] According to the circulating water treatment agent and its method of use of this embodiment, the excess mist of the paint 16 can be more efficiently coagulated, separated, and recovered, extending the usable period of the circulating water 20 and reducing the burden on workers. Furthermore, the circulating water 20 from which the paint components have been efficiently coagulated and separated can be used for a longer period of time, and a treatment method with less impact on the environment can be provided.

[0027] Furthermore, the paint components in the circulating water 20 quickly coagulate and float to form flocs. The flocs formed by coagulation can be separated and collected by methods such as floatation separation, screen collection, centrifuges, and filtration devices. The separated and collected sludge is dewatered by gravity or by a conventional method, and then used as fuel, whereas in the past it was incinerated or landfilled, making this a treatment method with less impact on the environment.

[0028] The present invention can be used for circulating water in a wet paint booth containing water-based paint, or for circulating water in a wet paint booth containing water-based paint and solvent-based paint, and can also be effectively applied to treating circulating water that produces a large amount of foam.

[0029] The circulating water treatment agent and its method of use of the present invention are not limited to the above-described embodiment, and are not limited to any particular paint or product. [Explanation of symbols]

[0030] 10 Wet Paint Booth 10a Application area 10b Adsorption area 12 products 14 Injector 16 Paint 20 Circulating water 22 Circulating water tank 24 Blower motor 26 Exhaust system 28 Draining board 30 Water flow path

Claims

1. A circulating water treatment agent that is added to the circulating water of a wet paint booth where products are painted, A circulating water treatment agent for a wet painting booth, characterized in that it contains a copolymer of basic aluminum chloride as a main component, contains 20 to 25% alumina, and contains 0.1 to 1% of an antifoaming agent.

2. 2. The circulating water treatment agent for a wet paint booth according to claim 1, wherein activated carbon is added in an amount of 0.5 to 1%.

3. A method for using a circulating water treatment agent by adding it to the circulating water of a wet paint booth where a product is painted, A method for using a circulating water treatment agent, comprising adding 0.1 to 0.5% of a circulating water treatment agent, the circulating water containing a copolymer of basic aluminum chloride as a main component, containing 20 to 25% alumina, and having added thereto 0.5 to 1% of an antifoaming agent, to the circulating water of the wet paint booth, further mixing in an alkaline agent containing calcium hydroxide as a main component, adjusting the pH of the circulating water to 8 to 10, and circulating the circulating water of the wet paint booth, so that excess paint during painting falls into and is adsorbed into the circulating water, and the paint components in the circulating water are coagulated by the circulating water treatment agent.

4. 4. The method for using the circulating water treating agent according to claim 3, wherein the paint components in the circulating water are coagulated to separate the paint components from the water component, and the water component is reused.

5. 4. The method for using the circulating water treatment agent according to claim 3, wherein the paint components separated from the water component by flocculation are recovered and dehydrated to be usable as fuel.

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