CN101205093B - Wet type coating chamber circulating water treatment agent and treatment method - Google Patents

Abstract

The present invention provides a wet coating booth circulating water treatment agent and a wet coating booth circulating water treatment method which can easily and efficiently coagulate and separate residual paint in the wet coating booth after being added to the circulating water of the wet coating booth. The wet coating room circulating water treatment agent is characterized in that it contains a cationic polymer having a cationic constituent unit derived from a quaternary ammonium salt of (meth)acrylic acid ester, and the quaternary ammonium It is formed by combining benzyl on the nitrogen atom of the salt; the treatment method of the circulating water of the wet coating room is to add the treatment agent to the circulating water of the wet coating room, and the remaining paint in the circulating water can be easily and efficiently coagulated separate.

Description

Circulating water treatment agent for wet coating room and treatment method for circulating water in wet coating room

technical field

The present invention relates to a treatment agent for circulating water in a wet-type painting room and a treatment method for circulating water in a wet-type painting room. A wet coating room circulating water treatment agent for a cationic polymer and a treatment method for wet coating room circulating water. The cationic polymer has a specific cationic constituent unit in which a benzyl group is bonded to a nitrogen atom of a quaternary ammonium salt.

Background technique

Conventionally, various paints have been sprayed in the painting process of the automobile industry, household appliances, and metal product manufacturing industries. Coatings used industrially are broadly classified into solvent-based coatings and water-based coatings, and various coatings are used alone or in combination.

Among them, water-based coatings are roughly divided into three types: water-soluble type, dispersion type, and emulsion type. They all use water as the main solvent, so they have the advantages of non-flammability, safety and hygiene, and no pollution caused by solvents. Therefore, In recent years, its scope of application has been continuously expanded.

However, in the coating process of various industries, etc., generally speaking, the utilization rate of the paint sprayed on the object to be coated is not 100%. For example, in the automobile industry, the utilization rate is about 60 to 80%. 40-20% becomes excess paint that must be removed in the next process. The excess paint that has been sprayed excessively is coagulated and discharged from the water system of the wet paint booth, while the treated water is recycled.

In this case, since the water-based paint is soluble or dispersed in water, solid-liquid separation is difficult, so it remains and accumulates in the circulating water of the wet paint booth, causing the following problems.

(a) The circulating water becomes highly viscous and viscous, which increases the load on the circulating pump, and when it becomes serious, it becomes impossible to circulate and the work stops.

(b) Insoluble paint after precipitation, sundries other than paint, and SS components can cause clogging failures in nozzles and piping systems, or adhere to water film plates, etc., causing failures.

(c) Bubbling failure occurs.

(d) The circulating water becomes corrupted due to high COD and high BOD, and the operating environment becomes bad due to the foul smell. Moreover, due to high COD and high BOD, wastewater treatment becomes difficult, and the load on the treatment equipment increases.

In order to solve such problems, coagulation and separation of the remaining paint in circulating water has been performed in the past. During the coagulation and separation, it is disclosed that: (1) combining a cationic polymer (cationic polymer flocculant) with an anionic polymer (anionic coagulant) (for example, refer to Patent Document 1); (2) add cationized cellulose and cationic polymer together (for example, refer to Patent Document 2); (3) aggregate inorganic A method of adding an agent and a high molecular weight polymer in combination (for example, refer to Patent Document 3).

Patent Document 1: Japanese Patent Publication No. 4-2317

Patent Document 2: Japanese Unexamined Patent Publication No. 7-713

Patent Document 3: JP-A-52-71538

Patent Document 4: JP-A-2004-337671

Patent Document 5: JP-A-2004-351362

Contents of the invention

However, in the above-mentioned conventional methods, the method of (1) using cationic polymers and anionic polymers has insufficient effects, and depending on the usage amount and usage ratio of cationic polymers and anionic polymers, and the treatment target The type and concentration of water-based coatings have very different coagulation effects, so there are problems such as difficult dosing control and unstable treatment.

In addition, the method of (2) using cationized cellulose increases the cost of reagents and is not practical. (3) The method of using an inorganic coagulant and a high molecular polymer has the following problems: not only is it difficult to set the optimum coagulation conditions (pH, reagent concentration, etc.), it is difficult to stabilize the treatment, and due to the generation of metal flocs, the The amount of paint sludge increases; the concentration of salts derived from inorganic coagulants increases, and there is a problem of equipment corrosion; the foaming substances mixed with water-based paint cannot be separated and removed, so the foaming in the paint room cannot be suppressed.

Furthermore, (4) a treatment method for circulating water in a wet coating booth using a combination of a phenolic resin and a cationic polymer (for example, refer to Patent Document 4); (5) a wet coating method using a polymer inverse emulsion as an essential component Paint mist treatment agent for chamber circulating water (for example, refer to Patent Document 5).

However, in the treatment method of (4) above, the cationic polymer used in combination with the phenolic resin is not limited, and the exemplified compound is a low-molecular-weight polymer, and it may not be possible to obtain sufficient coagulation effect and coagulation dross floating effect.

On the other hand, in the treatment agent of the above-mentioned (5), a combination of a polymer inverse phase emulsion and (a) an inorganic polyvalent metal, (b) a hydrophobic polymer emulsion, or (c) a clay mineral used in combination. The hydrophobic polymer emulsion exemplified here also includes the polymer used in the present invention, but it is not clearly stated that the polymer of the present invention containing a benzyl group (C ₆ H ₅ CH ₂ -) is particularly excellent.

The present invention solves the problems of the above-mentioned known techniques, and an object of the present invention is to provide a wet coating booth circulating water treatment agent that can easily and efficiently coagulate and separate residual paint in the circulating water after being added to the circulating water of the wet coating booth.

Another object of the present invention is to provide a method for treating circulating water in a wet painting booth that can easily and efficiently coagulate and separate residual paint in the circulating water by adding the treatment agent to the circulating water in the wet coating booth.

The inventors of the present invention have repeatedly conducted careful studies to achieve the above object, and found that a treatment agent containing a cationic polymer having a benzyl group bonded to the nitrogen atom of a quaternary ammonium salt can be used for this purpose. specific cationic building blocks.

It has also been found that by further containing at least one selected from the group consisting of phenolic resins, organic or inorganic coagulants, and defoamers in the above-mentioned treatment agent, the solid-liquid separation, flotation, and discharge of the remaining paint in the circulating water can be performed stably. .

The present invention has been accomplished based on the above findings.

That is, the present invention provides:

[1] A circulating water treatment agent for a wet-type painting booth, characterized in that it contains a cationic polymer having a cationic constituent unit derived from a quaternary ammonium salt of (meth)acrylate, and is Formed by combining a benzyl group on the nitrogen atom of the quaternary ammonium salt;

[2] According to the circulating water treatment agent for wet coating booths described in [1] above, the cationic polymer is a copolymer of (meth)acrylamide and (meth)acrylate quaternary ammonium salt;

[3] The circulating water treatment agent for wet coating booths described in [1] above, wherein the cationic polymer is a quaternary ammonium salt of a dialkylaminoalkyl (meth)acrylate and a quaternary ammonium salt of a (meth)acrylate ester. Copolymers of ammonium salts;

[4] The wet-type paint booth circulating water treatment agent according to the above [1], wherein the cationic polymer is a quaternary ammonium salt of (meth)acrylamide and dialkylaminoalkyl (meth)acrylate and ( Copolymers of quaternary ammonium salts of meth)acrylates;

[5] The circulating water treatment agent for wet coating booths according to any one of the above [1] to [4], wherein the quaternary ammonium salt of (meth)acrylate is (meth)acryloyloxyalkylbenzyl Dialkylammonium salts;

[6] The circulating water treatment agent for wet coating booths according to any one of the above [1] to [5], further containing at least one selected from the group consisting of phenolic resins, organic or inorganic coagulants, and defoamers ;

[7] A treatment method for circulating water in a wet coating booth, characterized in that the wet coating booth circulating water described in any one of the above [1] to [5] is added to the circulating water in a wet coating booth in a predetermined amount. water treatment agents; and

[8] According to the method for treating circulating water in wet coating booths described in [7] above, a wet coating agent further containing at least one selected from phenolic resins, organic or inorganic coagulants, and defoamers is added in a predetermined amount. Install chamber circulating water treatment agent.

According to the treatment agent for circulating water in a wet painting booth and the treatment method for circulating water in a wet coating booth according to the present invention, the residual paint in the circulating water in a wet coating booth can be easily and efficiently coagulated and separated.

Detailed ways

The wet coating room circulating water treatment agent (hereinafter, sometimes simply referred to as a room treatment agent) of the present invention is characterized in that it contains a cationic polymer (hereinafter, referred to as a cationic polymer (M)) having A cationic constituent unit derived from a quaternary ammonium salt of (meth)acrylate and formed by bonding a benzyl group to a nitrogen atom of the quaternary ammonium salt;

As a cationic structural unit of the cationic polymer (M) used for the room treatment agent of this invention, (A) structural unit represented by following general formula (I) is mentioned preferably.

In the general formula (I), R ¹ represents a hydrogen atom or a methyl group, and R ² and R ³ each independently represent an alkyl group having 1 to 4 carbon atoms. Examples of the alkyl group having 1 to 4 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl.

^A1 represents a straight-chain or branched-chain alkylene group having 2 to 4 carbon atoms, and specific examples include ethylene, propylene, trimethylene, and various butylenes. (X ¹ ) ^a- represents an anion of valence a. a is usually an integer of 1-3. Specific examples of the anion include halogen ions such as chloride, fluoride, bromide, and iodide, sulfate ions, nitrate ions, phosphate ions, methylsulfate ions, and perchlorate ions. Among them, preferred halide ions.

In the present invention, two or more different structural units (A) represented by the general formula (I) may be introduced into the polymer.

As a quaternary ammonium salt of (meth)acrylate of the monomer which forms this (A) structural unit, (meth)acryloxyalkyl benzyl dialkyl ammonium salt is mentioned. Specifically, [2-(acryloyloxy)ethyl]benzyldimethylammonium salt, [2-(acryloyloxy)ethyl]benzyldiethylammonium salt, [2-(acryloyloxy)ethyl]benzyldiethylammonium salt, [2-(acryloyloxy) Base) ethyl] benzyl ethyl methyl ammonium salt, [2-(methacryloyloxy) ethyl] benzyl dimethyl ammonium salt, [2-(methacryloyloxy) ethyl] Benzyldiethylammonium salt, [2-(methacryloyloxy)ethyl]benzylethylmethylammonium salt, [3-(acryloyloxy)propyl]benzyldimethylammonium salt , [3-(acryloyloxy)propyl]benzyldiethylammonium salt, [3-(acryloyloxy)propyl]benzylethylmethylammonium salt, [3-(methacryloyl) Oxy)propyl]benzyldimethylammonium salt, [3-(methacryloyloxy)propyl]benzyldiethylammonium salt, [3-(methacryloyloxy)propyl] Benzylethylmethylammonium salt, etc.

These monomers may be used alone or in combination of two or more.

In this way, a polymer having a cationic structural unit derived from a (meth)acrylate quaternary ammonium salt formed by bonding a benzyl group to the nitrogen atom of the quaternary ammonium salt, is bonded to the benzyl group having strong hydrophobicity. There is a hydrophobic portion of the remaining paint, a hydrophobic portion of the phenolic resin described later, and a hydrophobic portion of the defoamer. Furthermore, since this polymer is cationic, it is also easy to be anionic with the anion-charged paint particles. The phenolic resin binds and, as a result, forms firm flocs. In addition, since the polymer is strongly hydrophobic, the flocs are easily separated from water and easily floated up.

In the room treatment agent of the present invention, a copolymer having the above-mentioned (A) structural unit, a nonionic structural unit, and/or another cationic structural unit can be used as the cationic polymer (M). The nonionic structural unit and other cationic structural units are not particularly limited, but the copolymers shown below can be preferably used.

In the treatment agent of the present invention, as the cationic polymer (M), a copolymer having the above-mentioned (A) structural unit and a nonionic (B) structural unit represented by the following general formula (II) can be preferably used (Hereafter, referred to as copolymer (M-a)).

In the general formula (II), R ⁴ represents a hydrogen atom or a methyl group, and R ⁵ and R ⁶ each independently represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a dimethylaminoalkyl group. Examples of the alkyl group having 1 to 3 carbon atoms include methyl, ethyl, n-propyl and isopropyl. Examples of the dimethylaminoalkyl group include 2-dimethylaminoethyl, 3-dimethylaminopropyl and the like.

In the present invention, two or more different structural units (B) represented by the general formula (II) may be introduced into the copolymer (M-a).

Examples of the monomer forming the (B) constituent unit include acrylamide, N-methacrylamide, N-ethylacrylamide, N-isopropylacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, N,N-diisopropylacrylamide, N-ethyl-N-methacrylamide, methacrylamide, N-methylmethacrylamide, N-ethyl methacrylamide, N-isopropylmethacrylamide, N,N-dimethylmethacrylamide, N,N-diethylmethacrylamide, N,N-diisopropylmethacrylamide Acrylamide, N-ethyl-N-methylmethacrylamide, N-(2-dimethylaminoethyl)acrylamide, N-(2-dimethylaminoethyl)methacrylamide, N (meth)acrylamides such as (3-dimethylaminopropyl)acrylamide and N-(3-dimethylaminopropyl)methacrylamide.

These monomers may be used alone or in combination of two or more.

From the standpoint of the coagulation performance with respect to the remaining paint, etc., the content ratio of the above-mentioned (A) structural unit and (B) structural unit in the copolymer (M-a) is preferably 2:8 to 9:1 in terms of molar ratio, more preferably Preferably 3:7 to 6:4.

In the treatment agent of the present invention, as the cationic polymer (M), a copolymer (hereinafter , called copolymer (M-b)).

In the general formula (III), R ⁷ represents a hydrogen atom or a methyl group, and R ⁸ , R ⁹ and R ¹⁰ each independently represent an alkyl group having 1 to 4 carbon atoms. Examples of the alkyl group having 1 to 4 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl.

^A2 represents a straight-chain or branched-chain alkylene group having 2 to 4 carbon atoms, and specific examples thereof include ethylene, propylene, trimethylene, and various butylenes. (X ² ) ^b- represents an anion of valence number b. b is usually an integer of 1-3. Specific examples of the anion include halogen ions such as chloride, fluoride, bromide, and iodide, sulfate ions, nitrate ions, phosphate ions, methylsulfate ions, and perchlorate ions. Among them, preferred halide ions.

In the present invention, two or more different structural units (C) represented by the general formula (III) may be introduced into the copolymer (M-b).

(Meth)acryloyloxyalkyl (trialkyl) ammonium salt is mentioned as a monomer which forms this (C) structural unit. Specifically, [2-(acryloyloxy)ethyl]trimethylammonium salt, [2-(acryloyloxy)ethyl]triethylammonium salt, [2-(acryloyloxy)ethyl]trimethylammonium salt, [2-(acryloyloxy)ethyl] ] ethyl dimethyl ammonium salt, [2- (methacryloyloxy) ethyl] trimethyl ammonium salt, [2- (methacryloyloxy) ethyl] triethyl ammonium salt, [ 2-(Methacryloyloxy)ethyl]ethyldimethylammonium salt, [3-(acryloyloxy)propyl]trimethylammonium salt, [3-(acryloyloxy)propyl ]triethylammonium salt, [3-(acryloyloxy)propyl]ethyldimethylammonium salt, [3-(methacryloyloxy)propyl]trimethylammonium salt, [3- (methacryloyloxy)propyl]triethylammonium salt, [3-(methacryloyloxy)propyl]ethyldimethylammonium salt, and the like.

These monomers may be used alone or in combination of two or more.

From the standpoint of the cohesive performance of the remaining paint, etc., the content ratio of the above-mentioned (A) structural unit and (C) structural unit in the copolymer (M-b) is preferably 8:2 to 2:8 in terms of molar ratio, more preferably Preferably 6:4 to 4:6.

In the treating agent of the present invention, as the cationic polymer (M), one having the above-mentioned (A) structural unit, the above-mentioned nonionic (B) structural unit, and the above-mentioned cationic (C) structural unit can be used particularly preferably. Copolymer (hereinafter referred to as copolymer (M-c)).

From the standpoint of coagulation performance with respect to the remaining paint, etc., the content ratios of the above-mentioned (A) structural unit, (B) structural unit, and (C) structural unit in the copolymer (M-c) are preferably, on a molar basis, respectively 5-90%, 30-90% and 0-90%, more preferably 10-40%, 50-70% and 10-40%.

Representative examples of the copolymer (M-c) include acrylamide/[2-(acryloyloxy)ethyl]benzyldimethylammonium chloride/[2-(acryloyloxy)ethyl]trimonium chloride Methylammonium chloride, acrylamide/[3-(acryloyloxy)propyl]benzyldimethylammonium chloride/[2-(acryloyloxy)ethyl]trimethylammonium chloride, propylene Amide/[2-(acryloyloxy)ethyl]benzyldimethylammonium chloride/[3-(acryloyloxy)propyl]trimethylammonium chloride, acrylamide/[3-(acryloxy) Acyloxy)propyl]benzyldimethylammonium chloride/[3-(acryloyloxy)propyl]trimethylammonium chloride, etc.

From the point of view of coagulation performance to the remaining paint, etc., the weight average molecular weight of the cationic polymer (M) used in the treatment agent of the present invention is determined by gel permeation chromatography (GPC method) with 0.1 mol/L chlorine The value in terms of polyethylene glycol measured using sodium chloride aqueous solution as an eluent is preferably 6 million or more, more preferably 9 million to 11 million.

The polymerization method of the cationic polymer is not particularly limited, and a general polymerization method can be used. For example, in the case of aqueous solution polymerization, potassium persulfate, ammonium persulfate, 2,2'-azobis(2-amidinopropane) dihydrochloride, a redox initiator, etc. can be used as the polymerization initiator. In addition, in the case of reverse phase suspension polymerization, the same initiators as above can be used as the polymerization initiator. On the other hand, in the case of reverse phase emulsion polymerization, in addition to the above polymerization initiators, azobisisobutyronitrile, Polymerization with water insoluble initiators such as benzoyl peroxide.

The cationic polymer (M) can be used in any form of aqueous solution, suspension, or emulsion.

The treatment agent of the present invention may further contain at least one selected from the group consisting of phenolic resins, organic or inorganic coagulants, and antifoaming agents together with the cationic polymer (M).

The role of the above-mentioned phenolic resin has not been clarified, but it is estimated as follows.

The phenolic resin is dissolved in alkaline aqueous solution, etc., and injected into the circulating water of the wet coating booth, and the phenolic resin is dispersed in a dissolved state or a colloidal state. At this time, if the cationic polymer (M) is present, the charge of the phenolic resin will be neutralized to coagulate and insolubilize. On the other hand, the colloidal paint dissolved or dispersed in circulating water is also neutralized by the cationic polymer (M), thereby coagulating and insolubilizing. When the phenolic resin is insolubilized by the cationic polymer (M), the volume Flocculation and agglomeration in the form of the condensed paint. The flocs of phenolic resin agglomerated in the form of being entangled with paint become particles of a certain size, so they are easy to separate and remove from circulating water, and can be easily separated and removed by methods such as flotation separation, centrifugation, and filtration.

Examples of the phenolic resin used in the present invention include phenolic resins before crosslinking and curing, which are condensates of phenols such as phenol, cresol, and xylenol, and aldehydes such as formaldehyde, or modified products thereof. Specifically, condensates of phenol and formaldehyde, condensates of cresol and formaldehyde, condensates of xylenol and formaldehyde, alkyl-modified phenolic resins obtained by alkylating these phenolic resins, polyvinylphenol etc. These phenolic resins may be of the linear type or the resol type. The molecular weight is preferably 1000 or less. These phenol resins may be used alone or in combination of two or more.

Since these phenolic resins are hardly soluble in water, they are preferably used in the form of a solution or an emulsion by dissolving or dispersing them in a water-soluble solvent or the like. Examples of solvents used include ketones such as acetone, esters such as methyl acetate, water-soluble organic solvents such as alcohols such as methanol, aqueous alkali solutions, and amines, and are preferably dissolved in aqueous alkali solutions such as aqueous sodium hydroxide and potassium hydroxide.

When the phenolic resin is used as an alkaline aqueous solution, it is preferable that the alkaline aqueous solution has an alkaline reagent concentration of 1 to 25% by mass and a phenolic resin concentration of 1 to 50% by mass.

In the treatment agent of the present invention, the use ratio of the cationic polymer (M) and the phenolic resin is usually 5 to 20 times by mass, preferably 10 to 15 times by mass, relative to the cationic polymer (M). It is advantageous to use the phenolic resin in proportion.

Examples of the organic coagulant include dimethyldiallylammonium chloride polymer, alkylamine-epichlorohydrin condensate, ethyleneimine polymer, alkylene dichloride-polyalkylene Polyamine condensates, dimethylaminoethyl acrylate polymers, dimethylaminoethyl methacrylate polymers, polyvinylamidine and other cationic organic polymer compounds. These organic coagulants may be used alone or in combination of two or more.

Examples of the inorganic coagulant include polyaluminum chloride, aluminum sulfate, ferric chloride, ferrous sulfate, polyferric sulfate, and other polyvalent metal salts commonly used in water treatment. These inorganic coagulants may be used alone or in combination of two or more.

These coagulants are used for the purpose of forming floc particles by coagulating non-tacky paint, but organic coagulants are more preferable than inorganic coagulants from the viewpoint of coagulation performance, corrosion inhibition, and foaming suppression. .

In the treatment agent of the present invention, the use ratio of the cationic polymer (M) and the organic coagulant is usually 0.1 to 2 times the mass, preferably 1 to 1.5 times the mass of the cationic polymer (M). It is advantageous to use the organic coagulant in proportion.

The organic coagulant is preferably used in the form of an aqueous solution.

On the other hand, the above-mentioned antifoaming agent is not particularly limited, and any antifoaming agent may be appropriately selected from conventionally used antifoaming agents for circulating water in wet coating booths. As the antifoaming agent, for example, hydrophobic organic solvents, polyvalent metal salts of fatty acids, hydrophobic inorganic powders, antifoaming nonionic surfactants and the like can be used.

Examples of hydrophobic organic solvents include paraffinic hydrocarbons, naphthenic hydrocarbons, and petroleum solvents. Examples of polyvalent metal salts of fatty acids include dodecanoic acid, hexadecanoic acid, octadecanoic acid, and oleic acid. Magnesium, aluminum, calcium, iron, zinc, nickel, barium and other metal salts of fatty acids such as erucic acid and erucic acid.

Examples of hydrophobic inorganic powders include hydrophobic silicon oxide, aluminum oxide, and magnesium oxide. Examples of nonionic surfactants include glycerin fatty acid esters, sorbitan fatty acid esters, polyethylene glycol Fatty acid esters such as fatty acid esters, polyethylene glycol, polyoxyethylene polyoxypropylene (Pluronic type, Tetronic type), ether types such as polyoxyethylene alkyl ethers, and the like.

These antifoamers may be used alone or in combination of two or more.

The defoamer is used to make the solid-liquid separation of the remaining paint, the floating of the dross, and the discharge stable.

In the processing agent of the present invention, the usage-amount of the antifoaming agent is usually selected in a range of 3 to 30 times the mass, preferably 3 to 10 times the mass, of the cationic polymer (M).

The circulating water treatment agent for wet coating booths of the present invention contains, as an essential component, a cationic polymer (M), which is formed by bonding a benzyl group to a nitrogen atom of a quaternary ammonium salt, and has A cationic constituent unit derived from a quaternary ammonium salt of (meth)acrylate, and if necessary, the wet coating room circulating water treatment agent of the present invention further contains At least 1 of them.

The treatment method of the circulating water in the wet-type coating booth of the present invention is to add a cationic polymer (M) as an essential component, and a phenolic resin, an organic or an inorganic condensate, etc. Agent, defoamer, these reagents can be added at the same place or at different places. In addition, the processing agent containing all these components may be added at once, or may be separately added at different places.

The addition amount of the treatment agent of the present invention to the circulating water in the wet coating room is determined in consideration of the floating and separating properties of the paint sludge, and the concentration of the above-mentioned cationic polymer (M) is usually about 10 to 300 mg/L, preferably 20 mg/L. ~100mg/L.

According to the treatment agent and treatment method of the present invention, by adding it to the circulating water of a wet-type painting booth in this way, the remaining paint in the circulating water can be aggregated and separated easily and efficiently.

The agglomerated flocs of the remaining paint formed by adding the treatment agent of the present invention to the circulating water of the wet paint booth are separated by, for example, floating separation, wedge wire (wedge wire), rotary screen, bar screen (bar screen), and cyclone separation. separator, centrifuge, filter device, etc. to separate and recover. After the separated and recovered sludge is dehydrated by gravity or dehydrated by the usual method, it is calcined and buried.

Example

The present invention will be further described in detail through examples below, but the present invention is not limited by these examples.

In addition, the performance of each reagent was evaluated by the method shown below.

<Test method>

Add 800 mL of tap water in Nogi Town, Tochigi Prefecture and 8 mL of paint (water-based acrylic paint) into a 1 L beaker, add a specified amount of reagent while stirring with a magnetic stirrer (500 rpm) and stir for 3 minutes, and observe the slurry after standing for 10 minutes The coagulation and buoyancy were evaluated according to the following standards, and the turbidity was measured according to the following method.

(1) Coagulation

◎: flocs over 10mm

○: Flocs of 5 mm or more and less than 10 mm

△: Flocs of more than 2mm and less than 5mm

×: Flocs less than 2mm

(2) Floatability

◎: Almost all floated up

○: About half of the quantity goes up

△: Partially floating

×: Almost no floating

(3) Turbidity

The value expressed is the transmitted light turbidity measured in accordance with 9.2 of JIS K0101 (using kaolin as a turbidity standard solution).

Embodiment 1 and Comparative Examples 1-4

The type and amount of each polymer shown in Table 1 were added to a 1% by mass solution of the paint (aqueous acrylic paint) to evaluate the performance of the reagent. The results are shown in Table 1. In addition, evaluation was performed in the same manner for a blank to which no polymer was added (Reference Example 1).

[Table 1]

Table 1

[Note]

Polymer 1: Acrylamide/[2-(acryloyloxy)ethyl]benzyldimethylammonium chloride/[2-(acryloyloxy)ethyl]trimethylammonium chloride copolymer, copolymer Molar ratio 66/17/17, weight average molecular weight 10 million

Polymer 2: A polymer of dimethylaminoethyl methacrylate·chloromethane, with a weight average molecular weight of 9 million

Polymer 3: Copolymer of acrylamide/[2-(acryloyloxy)ethyl]trimethylammonium chloride, copolymerization molar ratio 90/10, weight average molecular weight 6 million

Polymer 4: acrylamide/sodium acrylate copolymer, copolymerization molar ratio 77/23, weight average molecular weight 8 million

Polymer 5: [2-(methacryloxy)ethyl]trimethylammonium chloride/[2-(acryloyloxy)ethyl]trimethylammonium chloride/acrylic acid/acrylamide copolymer , copolymerization molar ratio 15/15/10/60, weight average molecular weight 9 million

It can be seen from Table 1 that the reagent of Example 1 has excellent performance compared with the reagents of Comparative Examples 1-4.

Embodiment 2 and Comparative Examples 5-8

To a 1% by mass solution of the coating paint (water-based acrylic paint), each polymer of the type and amount shown in Table 2 and 600 mg/L of polymer 6 and 150 mg/L of polymer 7 were added to perform the performance of the reagent. evaluate. The results are shown in Table 2. In addition, evaluation was performed in the same manner for a reagent in which no other polymer was added other than 600 mg/L of Polymer 6 and 150 mg/L of Polymer 7 (Reference Example 2).

[Table 2]

Table 2

(Add each polymer shown in the table as well as Polymer 6: 600mg/L and Polymer 7: 150mg/L)

[Note]

Polymer 1 to Polymer 5: Same as footnotes in Table 1.

Polymer 6: Phenol formaldehyde condensate, linear, molecular weight about 1700

Polymer 7: Dimethylamine·epichlorohydrin condensate, weight average molecular weight 100,000

It can be seen from Table 2 that the reagent of Example 2 has excellent performance compared with the reagents of Comparative Examples 5-8.

The treatment agent for circulating water in a wet coating booth of the present invention and the method for treating circulating water in a wet coating booth using the same can coagulate and separate residual paint in circulating water in a wet coating booth easily and efficiently.

Claims (2)

1. A circulating water treatment agent for a wet coating room, characterized in that it is made of cationic polymer, phenolic resin and organic coagulant, The cationic polymer is a copolymer of (meth)acrylamides, (meth)acryloxyalkylbenzyldialkylammonium salts and quaternary ammonium salts of (meth)acrylic acid esters, with a weight average molecular weight of More than 6 million, the weight average molecular weight is the value converted into polyethylene glycol measured by gel permeation chromatography and using 0.1 mol/L sodium chloride aqueous solution as eluent, The amount of the phenolic resin used is 5 to 20 times the mass of the cationic polymer. 2. A treatment method for circulating water in a wet-type painting room, characterized in that, the circulating water treatment agent for wet-type painting room according to claim 1 is added to the circulating water in a wet-type painting room.