JP6279505B2 - Wet paint booth circulating water treatment agent and wet paint booth circulating water treatment method - Google Patents

Description

  The present invention relates to a wet paint booth circulating water treatment agent and a wet paint booth circulating water treatment method. More specifically, the present invention relates to a wet paint booth circulating water treatment agent capable of imparting floatability to sludge in the wet paint booth circulating water and reducing the amount of sludge accumulated in a water tank, and the water treatment agent. The present invention relates to a method for treating circulating water in a wet paint booth.

  The painting booth is a production facility necessary for painting work that is configured to discharge spray mist. The painting booth has a function to properly discharge organic solvents generated during spraying work to the outdoors, an effective capture function for unpainted paint generated by overspray, and dust on the coating to improve the coating quality. Appropriate functions for generating suction air speed to prevent adhesion and protect the human hygiene environment are required. At the wet painting booth, unpainted paint is collected with circulating water. In order to remove the uncoated paint collected in the circulating water, a water treatment method using a combination of an inorganic flocculant such as polyaluminum chloride and a nonionic polymer flocculant aid (Patent Document 1), melamine A method of treating water using an aldehyde acid colloid solution (Patent Document 2) has been proposed.

  Sludge can be obtained by agglomerating the uncoated paint with the above chemicals. The sludge is removed from the circulating water by a known method. However, sludge having a specific gravity greater than that of water tends to accumulate in a water tank or the like. In addition, inorganic flocculants and high hydrophilic polymer flocculants that are added for flocculation of uncoated paints themselves tend to settle, and they may accumulate in a water tank or the like.

  In order to remove the uncoated paint, a method (Patent Document 3) in which a water treatment is performed using a phenol resin and a cationic polymer in combination has been proposed. In this method, since the cationic polymer neutralizes the anionic property of the phenol resin, it seems that an effect of floating sludge and reducing sludge accumulation can be expected. However, in order to obtain a sufficient floating effect, a large amount of cationic polymer must be added.

JP 52-71538 A JP 62-266159 A JP 2004-337671 A

  An object of the present invention is to provide a wet paint booth circulating water treatment agent capable of imparting floatability to sludge in the wet paint booth circulating water and reducing the amount of sludge accumulated in a water tank, and the water treatment agent. The wet paint booth was to provide a method of treating circulating water.

  As a result of studies to achieve the above object, the present invention including the following embodiments has been completed.

（式（A）中、
Ｒ¹は水素原子またはメチル基であり、
Ｒ²およびＲ³はそれぞれ独立に炭素数１〜４のアルキル基であり、
Ｒ⁴は水素原子、炭素数１〜４のアルキル基またはベンジル基であり、
ＹはＯまたはＮＨであり
ｎは括弧内の繰り返し数を表し且つ２〜５のいずれかの整数であり、
Ｚ^-は対アニオンである。） [1] A wet paint booth circulating water treatment agent containing a copolymer having a structural unit derived from a monomer represented by the formula (A) and a structural unit derived from styrene.

(In formula (A),
R ¹ is a hydrogen atom or a methyl group,
R ² and R ³ are each independently an alkyl group having 1 to 4 carbon atoms,
R ⁴ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a benzyl group,
Y is O or NH, n represents the number of repetitions in parentheses and is an integer from 2 to 5,
Z ⁻ is a counter anion. )

[2] The wet paint booth circulating water treatment agent according to [1], wherein the counter anion is a halogen ion, a sulfate ion, a phosphate ion, a borate ion or an organic acid anion.
[3] The wet paint booth circulating water treatment agent according to [1], further containing an inorganic coagulant.

[4] A method for treating circulating water in a wet coating booth, comprising adding the water treatment agent according to any one of [1] to [3] to the circulating water.
[5] The wet coating booth circulation according to [4], wherein the addition of the water treatment agent to the circulating water is performed in at least one of the coating booth, the water tank, the solid-liquid separator, and the piping connecting them. Water treatment method.
[6] The method for treating circulating water in a wet coating booth according to [4] or [5], further comprising adding a tackifier to the circulating water.
[7] The wet paint booth circulating water treatment method according to any one of [4] to [6], further comprising adding a coagulant to the circulating water.
[8] The method for treating wet paint booth circulating water according to any one of [4] to [7], further comprising adding a polymer flocculant to the circulating water.

  The water treatment agent according to the present invention is excellent in the condensation effect due to charge neutralization. Furthermore, since the water treatment agent according to the present invention does not settle and deposit itself, and even if it is used in a small amount, it can impart levitating property to the sludge in the circulating water, so sludge accumulation can be reduced. The water treatment agent according to the present invention can improve the coagulation effect by charge neutralization and reduce sludge accumulation more effectively by using in combination with an inorganic coagulant, particularly an aluminum coagulant.

  Such effects of the present invention are presumed to have the following effects. The water treatment agent according to the present invention has a structural unit derived from the monomer represented by the formula (A) and a structural unit derived from styrene. The structural unit derived from the monomer represented by the formula (A) is a cationic structural unit. The surface of the uncoated paint is usually at a negative potential. The surface potential of the uncoated paint is set to a value close to zero for the structural unit derived from the monomer represented by the formula (A), for example, about −5 μeq / L, and aggregated flocs are generated due to attractive force between particles. Make it easier. On the other hand, the structural unit derived from styrene is a hydrophobic structural unit. Wet paint booth circulating water contains a lot of bubbles due to liquid dropping, air entrainment from free surface due to shaking (slosh phenomenon), and floating of air staying in the system. The bubbles are hydrophobic. Since the sludge obtained by aggregating with the water treatment agent according to the present invention contains structural units derived from hydrophobic styrene, it has a strong affinity with hydrophobic bubbles. A large number of bubbles adhere to the sludge, and the floating property can be improved.

It is a figure which shows the turbidity of the bottom part of the treated water with respect to the addition amount of a water treating agent. It is a figure which shows the turbidity of filtered water with respect to the addition amount of a water treatment agent. It is a figure which shows the turbidity of the bottom part of the treated water with respect to the addition amount of a water treating agent. It is a figure which shows the turbidity of filtered water with respect to the addition amount of a water treatment agent. It is a conceptual diagram which shows the structure of a test apparatus. It is a conceptual diagram which shows one structural example of the processing apparatus of wet coating booth circulating water.

  The wet paint booth circulating water treatment agent according to the present invention is a structural unit derived from the monomer represented by the formula (A) (hereinafter sometimes referred to as unit (a)) and a structural unit derived from styrene ( Hereinafter, a copolymer having a unit (b)) (hereinafter also referred to as a cationic ST copolymer) is contained.

（式（A）中、
Ｒ¹は水素原子またはメチル基であり、
Ｒ²およびＲ³はそれぞれ独立に炭素数１〜４のアルキル基であり、
Ｒ⁴は水素原子、炭素数１〜４のアルキル基またはベンジル基であり、
ＹはＯまたはＮＨであり、
ｎは括弧内の繰り返し数を表し且つ２〜５のいずれかの整数であり、且つ
Ｚ^-は対アニオンである。）

(In formula (A),
R ¹ is a hydrogen atom or a methyl group,
R ² and R ³ are each independently an alkyl group having 1 to 4 carbon atoms,
R ⁴ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a benzyl group,
Y is O or NH;
n represents the number of repetitions in parentheses and is an integer of 2 to 5, and Z ⁻ is a counter anion. )

The alkyl group having 1 to ⁴ carbon atoms in R ² , R ³ or R ⁴ may be linear or branched. Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, and a t-butyl group.

The counter anion in Z ⁻ is not particularly limited, but is preferably a halogen ion, a sulfate ion, a phosphate ion, a borate ion or an organic acid anion, and more preferably a halogen ion. Examples of the halogen ion include chlorine ion, fluorine ion, bromine ion and iodine ion. Of these, chlorine ions are preferred.

  Examples of the monomer represented by the formula (A) include 2- (meth) acryloxyethyldimethylammonium salt, 3- (meth) acryloxypropyldimethylammonium salt, 4- (meth) acryloxybutyldimethylammonium. Salt, 5- (meth) acryloxypentyldimethylammonium salt, 2- (meth) acryloxyethyl diethylammonium salt, 3- (meth) acryloxypropyldiethylammonium salt, 4- (meth) acryloxybutyldiethylammonium salt, 2- (meth) acryloxyethyl di n-propylammonium salt, 3- (meth) acryloxypropyl di n-propylammonium salt, 4- (meth) acryloxybutyldi n-propylammonium salt, 2- (meth) Acryloxyethyl diisopropylammonium salt, 3- (meth) acryloxypropyl diisopropylammonium salt, 4- (meth) acryloxybutyl diisopropylammonium salt, 2- (meth) acryloxyethyl di n-butylammonium salt, 3- (meth) acryloxypropyl di n- Butyl ammonium salt, 4- (meth) acryloxybutyl di n-butyl ammonium salt, 2- (meth) acryloxyethyl di sec-butyl ammonium salt, 3- (meth) acryloxypropyl di sec-butyl ammonium salt, 4 -(Meth) acryloxybutyldisec-butylammonium salt, 2- (meth) acryloxyethyldiisobutylammonium salt, 3- (meth) acryloxypropyldiisobutylammonium salt, 4- (meth) acryloxybutyldiisobutylammonium salt;

  2- (meth) acryloxyethyltrimethylammonium salt, 3- (meth) acryloxypropyltrimethylammonium salt, 4- (meth) acryloxybutyltrimethylammonium salt, 5- (meth) acryloxypentyltrimethylammonium salt, 2- (Meth) acryloxyethyl triethylammonium salt, 3- (meth) acryloxypropyltriethylammonium salt, 4- (meth) acryloxybutyltriethylammonium salt, 2- (meth) acryloxyethyltri-n-propylammonium salt, 3 -(Meth) acryloxypropyltri-n-propylammonium salt, 4- (meth) acryloxybutyltri-n-propylammonium salt, 2- (meth) acryloxyethyltriisopropylammonium salt, 3- (meth) acrylic Xylpropyltriisopropylammonium salt, 4- (meth) acryloxybutyltriisopropylammonium salt, 2- (meth) acryloxyethyltri-n-butylammonium salt, 3- (meth) acryloxypropyltrin-butylammonium salt, 4- (meth) acryloxybutyltri-n-butylammonium salt, 2- (meth) acryloxyethyltri-sec-butylammonium salt, 3- (meth) acryloxypropyltri-sec-butylammonium salt, 4- (meth) Acryloxybutyltri-sec-butylammonium salt, 2- (meth) acryloxyethyltriisobutylammonium salt, 3- (meth) acryloxypropyltriisobutylammonium salt, 4- (meth) acryloxybutyltriisobutylammonium salt;

  2- (meth) acryloxyethyldimethylbenzylammonium salt, 3- (meth) acryloxypropyldimethylbenzylammonium salt, 4- (meth) acryloxybutyldimethylbenzylammonium salt, 5- (meth) acryloxypentyldimethylbenzylammonium salt Salt, 2- (meth) acryloxyethyl diethylbenzylammonium salt, 3- (meth) acryloxypropyldiethylbenzylammonium salt, 4- (meth) acryloxybutyldiethylbenzylammonium salt, 2- (meth) acryloxyethyldi n-propylbenzylammonium salt, 3- (meth) acryloxypropyldi n-propylbenzylammonium salt, 4- (meth) acryloxybutyldi n-propylbenzylammonium salt, 2- (meth) acrylo Cyethyldiisopropylbenzylammonium salt, 3- (meth) acryloxypropyldiisopropylbenzylammonium salt, 4- (meth) acryloxybutyldiisopropylbenzylammonium salt, 2- (meth) acryloxyethyldi n-butylbenzylammonium salt, 3 -(Meth) acryloxypropyldi n-butylbenzylammonium salt, 4- (meth) acryloxybutyldin-butylbenzylammonium salt, 2- (meth) acryloxyethyldisec-butylbenzylammonium salt, 3- ( (Meth) acryloxypropyl disec-butylbenzylammonium salt, 4- (meth) acryloxybutyldisec-butylbenzylammonium salt, 2- (meth) acryloxyethyldiisobutylbenzylammonium salt, 3- (meth) a Lilo propyl diisobutyl benzyl ammonium salts, 4- (meth) acryloxy-butyl diisobutyl benzyl ammonium salts;

  2- (meth) acryloylaminoethyldimethylammonium salt, 3- (meth) acryloylaminopropyldimethylammonium salt, 4- (meth) acryloylaminobutyldimethylammonium salt, 5- (meth) acryloylaminopentyldimethylammonium salt, 2- (Meth) acryloylaminoethyldiethylammonium salt, 3- (meth) acryloylaminopropyldiethylammonium salt, 4- (meth) acryloylaminobutyldiethylammonium salt, 2- (meth) acryloylaminoethyldi-n-propylammonium salt, 3 -(Meth) acryloylaminopropyldi n-propylammonium salt, 4- (meth) acryloylaminobutyldin-propylammonium salt, 2- (meth) acryloylaminoethyldi Propyl ammonium salt, 3- (meth) acryloylaminopropyl diisopropylammonium salt, 4- (meth) acryloylaminobutyl diisopropylammonium salt, 2- (meth) acryloylaminoethyl di-n-butylammonium salt, 3- (meth) acryloylamino Propyl di n-butylammonium salt, 4- (meth) acryloylaminobutyl di n-butylammonium salt, 2- (meth) acryloylaminoethyl disec-butylammonium salt, 3- (meth) acryloylaminopropyldisec-butyl Ammonium salt, 4- (meth) acryloylaminobutyldisec-butylammonium salt, 2- (meth) acryloylaminoethyldiisobutylammonium salt, 3- (meth) acryloylaminopropyldiisobutylan Salt, 4- (meth) acryloyloxy-aminobutyl diisobutyl ammonium salt,

  2- (meth) acryloylaminoethyltrimethylammonium salt, 3- (meth) acryloylaminopropyltrimethylammonium salt, 4- (meth) acryloylaminobutyltrimethylammonium salt, 5- (meth) acryloylaminopentyltrimethylammonium salt, 2- (Meth) acryloylaminoethyltriethylammonium salt, 3- (meth) acryloylaminopropyltriethylammonium salt, 4- (meth) acryloylaminobutyltriethylammonium salt, 2- (meth) acryloylaminoethyltrin-propylammonium salt, 3 -(Meth) acryloylaminopropyltri-n-propylammonium salt, 4- (meth) acryloylaminobutyltri-n-propylammonium salt, 2- (meth) acrylo Ruaminoethyltriisopropylammonium salt, 3- (meth) acryloylaminopropyltriisopropylammonium salt, 4- (meth) acryloylaminobutyltriisopropylammonium salt, 2- (meth) acryloylaminoethyltrin-butylammonium salt, 3 -(Meth) acryloylaminopropyltri-n-butylammonium salt, 4- (meth) acryloylaminobutyltri-n-butylammonium salt, 2- (meth) acryloylaminoethyltri-sec-butylammonium salt, 3- (meth) acryloyl Aminopropyltri sec-butylammonium salt, 4- (meth) acryloylaminobutyltrisec-butylammonium salt, 2- (meth) acryloylaminoethyltriisobutylammonium salt, 3- (meth) a Leroy Le aminopropyl triisobutyl ammonium salts, 4- (meth) acryloyloxy-aminobutyl triisobutyl ammonium salts;

  2- (meth) acryloylaminoethyldimethylbenzylammonium salt, 3- (meth) acryloylaminopropyldimethylbenzylammonium salt, 4- (meth) acryloylaminobutyldimethylbenzylammonium salt, 5- (meth) acryloylaminopentyldimethylbenzylammonium salt Salt, 2- (meth) acryloylaminoethyl diethylbenzylammonium salt, 3- (meth) acryloylaminopropyldiethylbenzylammonium salt, 4- (meth) acryloylaminobutyldiethylbenzylammonium salt, 2- (meth) acryloylaminoethyldi n-propylbenzylammonium salt, 3- (meth) acryloylaminopropyldi n-propylbenzylammonium salt, 4- (meth) acryloylaminobuty Di-n-propylbenzylammonium salt, 2- (meth) acryloylaminoethyldiisopropylbenzylammonium salt, 3- (meth) acryloylaminopropyldiisopropylbenzylammonium salt, 4- (meth) acryloylaminobutyldiisopropylbenzylammonium salt, 2- ( (Meth) acryloylaminoethyldi n-butylbenzylammonium salt, 3- (meth) acryloylaminopropyldi n-butylbenzylammonium salt, 4- (meth) acryloylaminobutyldi n-butylbenzylammonium salt, 2- (meth) Acryloylaminoethyl disec-butylbenzylammonium salt, 3- (meth) acryloylaminopropyldisec-butylbenzylammonium salt, 4- (meth) acryloylaminobutyldise c-butylbenzylammonium salt, 2- (meth) acryloylaminoethyldiisobutylbenzylammonium salt, 3- (meth) acryloylaminopropyldiisobutylbenzylammonium salt, 4- (meth) acryloylaminobutyldiisobutylbenzylammonium salt; Can do. “(Meth) acryloyl” means “methacryloyl” or “acryloyl”. Of these, 2- (meth) acryloyloxyethyltrimethylammonium salt is preferred. Examples of the ammonium salt include ammonium halide, ammonium sulfate, ammonium phosphate, ammonium borate, and ammonium nitrate.

  The unit (a) contained in the cationic ST copolymer may be derived from only one monomer among the monomers represented by the formula (A) or different. It may be derived from two or more monomers.

  The amount of the unit (a) contained in the cationic ST copolymer is not particularly limited, but is preferably 10 to 90 mol%, more preferably 20 to 80 mol%. When the amount of the unit (a) is in the above range, the condensation effect and the floating property improvement effect due to charge neutralization become higher.

  The amount of the unit (b) contained in the cationic ST copolymer is not particularly limited, but is preferably 10 to 90 mol%, more preferably 20 to 80 mol%. When the amount of the unit (b) is in the above range, the condensation effect and the floating property improvement effect by charge neutralization are further enhanced.

The cationic ST copolymer used in the present invention is a structural unit derived from the monomer (C) other than the monomer represented by the formula (A) and styrene (hereinafter referred to as unit (c)). May also be included. As the monomer (C), acrylamide, methacrylamide, N-methylacrylamide, N-ethylacrylamide, N-isopropylacrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, N, N-diisopropylacrylamide, N-ethyl-N-methylacrylamide, methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N-isopropylmethacrylamide, N, N-dimethylmethacrylamide, N, N-diethylmethacrylamide, N, N- Diisopropyl methacrylamide, N-ethyl-N-methyl methacrylamide, N- (2-dimethylaminoethyl) acrylamide, N- (2-dimethylaminoethyl) methacrylamide, N- (3-dimethylaminopropyl) Ethylenically unsaturated carboxylic acid amides such as acrylamide and N- (3-dimethylaminopropyl) methacrylamide; ethylenically unsaturated nitriles such as acrylonitrile and methacrylonitrile; acrylic acid, methacrylic acid, maleic acid, itaconic acid and the like Ethylenically unsaturated carboxylic acid and alkali metal salts thereof; ethylenically unsaturated carboxylic acid ester such as acrylic acid ester and methacrylic acid ester; vinyl chloride, vinylidene chloride, ethylene, propylene, vinyl acetate; α-methylstyrene, 4-methyl Examples include styrene.
The amount of the unit (c) contained in the cationic ST copolymer is not particularly limited, but is preferably 80 mol% or less, more preferably 60 mol% or less. When the amount of the unit (c) is in the above range, the condensation effect or the floating property improvement effect by charge neutralization may be further increased.

  The cationic ST copolymer used in the present invention is obtained by an addition polymerization reaction at an ethylenically unsaturated bond in each monomer. The method for performing the addition polymerization reaction is not particularly limited. For example, the method of carrying out radical addition polymerization reaction of each monomer with a polymerization initiator can be mentioned. Polymerization initiators include persulfates such as potassium persulfate and ammonium persulfate; azo compounds such as 2,2′-azobis (2-amidinopropane) dihydrochloride and azobisisobutyronitrile; benzoyl peroxide and the like Organic peroxides: redox initiators composed of a combination of an oxidizing agent and a reducing agent, such as hydrogen peroxide and iron (II) salt, persulfate and sodium hydrogen sulfite, and the like. The polymerization reaction can be performed by an aqueous solution polymerization method, an emulsion polymerization method, a reverse phase emulsion polymerization method, an O / W suspension polymerization method, a W / O suspension polymerization method (reverse phase suspension polymerization method), or the like. Among these, the aqueous solution polymerization method and the reverse phase suspension polymerization method are preferable.

  The cationic ST copolymer used in the present invention has a weight average molecular weight of preferably 20,000 to 100,000. If the weight average molecular weight is 100,000 or less, the viscosity of the solution in which the copolymer is dissolved does not increase, and it is easy to diffuse uniformly into the circulating water. If the weight average molecular weight is 20,000 or more, the effect of imparting the floating property to the sludge is high. The weight average molecular weight is a value calculated in terms of the molecular weight of standard polyethylene glycol based on a gel permeation chromatogram measured using a 0.1 mol / L sodium chloride aqueous solution as an eluent.

  The cationic ST copolymer used in the present invention is not particularly limited by the intrinsic viscosity ([η]), but the intrinsic viscosity in a 0.2N saline solution at 25 ° C. is 0.05 to 5 dl / g. Preferably there is. In addition, the intrinsic viscosity ([η]) is measured using a Cannon-Fenske Routine viscometer, and the flow time is measured, and the Huggins formula and Mead-Fuoss formula are used from the measured values. This is a calculated value.

  The addition amount of the cationic ST copolymer (solid content) used in the present invention is preferably 5 mg or more, more preferably 10 to 30 mg with respect to 1 L of wet coating booth circulating water. The addition amount of the cationic ST copolymer (solid content) used in the present invention is preferably 0.5 to 10% by mass, more preferably 0.8 to 7%, based on the paint (solid content) in the circulating water. % By mass. Furthermore, the addition amount of the cationic ST copolymer is preferably 0.001 to 1 meq / L, more preferably 0.002 to 0.5 meq / L, as a colloid equivalent value with respect to circulating water.

  The cationic ST copolymer used in the present invention may be in any form such as powder, aqueous solution, suspension or emulsion. In the case of an aqueous solution, suspension or emulsion, the concentration of the cationic ST copolymer (solid content) in the water treatment agent is not particularly limited, but the storage stability of the water treatment agent and the transportation cost are related. It is preferable that it is 15-50 mass%. In the form of a suspension or emulsion, a surfactant, a dispersing agent and the like may be included.

The water treatment agent according to the present invention may contain other chemicals in addition to the cationic ST copolymer. Examples of other chemicals that can be contained in the water treatment agent according to the present invention include a tackifier, a coagulant, a polymer flocculant, and a pH adjuster. Of these, inorganic coagulants are preferable, and aluminum coagulants are more preferable.
The mass ratio of the inorganic coagulant (solid content, in terms of Al ₂ O _{3 in} the case of an aluminum coagulant) contained in the water treatment agent according to the present invention: the cationic ST copolymer (solid content) is not particularly limited. However, it is preferably 50:50 to 99: 1, more preferably 70:30 to 90:10. The water treatment agent in which the inorganic coagulant and the cationic ST copolymer are blended may be in any form such as powder, aqueous solution, suspension, and emulsion. In the case of an aqueous solution, suspension or emulsion, each of an inorganic coagulant (solid content, in the case of an aluminum-based coagulant, Al ₂ O ₃ equivalent) and a cationic ST copolymer (solid content) in the water treatment agent. The concentration of is not particularly limited, but the inorganic coagulant (solid content, in the case of an aluminum coagulant, converted to Al ₂ O ₃ ) is 5 to 30 because of the storage stability of the water treatment agent and the transportation cost. The mass% and the cationic ST copolymer (solid content) are preferably 1 to 10 mass%. Further, in the form of a suspension or an emulsion, a surfactant, a dispersant and the like may be further included. By containing the inorganic coagulant and the cationic ST copolymer together, the floatability can be further improved and sludge redispersion can be prevented. In addition, sludge is composted, leading to a reduction in waste.

  The water treatment agent according to the present invention can be added to wet booth circulating water together with other chemicals. Examples of other agents include a non-adhesive agent, a coagulant, a polymer flocculant, and a pH adjuster.

The detackifying agent used in the present invention is a known compound capable of detackifying an uncoated paint in wet booth circulating water.
Examples of tackifiers include phenolic resins, carboxylic acid polymers, tannin compounds, tannin base polymers, melamine formaldehyde condensates, melamine dicyandiamide condensates, linear cationic polyamines, sodium zincate, alumina sol, etc. Can be mentioned. The tackifier may be used alone or in combination of two or more. Among these, an anionic detackifying agent is preferable from the viewpoint of detackifying performance, and a phenolic resin or a carboxylic acid polymer is more preferable.

  The phenolic resin employed as the tackifier is a condensate of phenols and aldehydes or a modified product thereof, and is a product before crosslinking and curing. Specific examples of the phenolic resin include a condensate of phenol and formaldehyde, a condensate of cresol and formaldehyde, and a condensate of xylenol and formaldehyde. Examples of modified products include alkyl-modified phenolic resins and polyvinylphenol. These phenolic resins may be novolak type or resol type. The phenolic resin is not particularly limited depending on the molecular weight and other physical properties, and can be appropriately selected from those generally used for wet coating booth circulating water treatment. These phenolic resins may be used alone or in combination of two or more.

  Phenolic resins are usually poorly soluble in water. The phenolic resin is preferably used in the form of a solution or emulsion by dissolving or dispersing it in a solvent having a high affinity with water. Examples of the solvent used include ketones such as acetone, esters such as methyl acetate, alcohols such as methanol, alkaline aqueous solutions, and amines. Of these solvents, an aqueous alkali solution is preferred. Examples of the alkaline aqueous solution include a sodium hydroxide aqueous solution and a potassium hydroxide aqueous solution. In a product obtained by dissolving or dispersing a phenolic resin in an aqueous alkali solution, the concentration of the alkali component is preferably 1 to 25% by mass, and the concentration of the phenolic resin is preferably 1 to 50% by mass.

  The addition amount of the phenol-based resin (solid content) is preferably 1 mg or more, more preferably 5 mg or more with respect to 1 L of the wet coating booth circulating water from the viewpoint of tack-free performance. From the viewpoint of suppressing excessive foaming and an increase in operating cost, the upper limit of the amount of phenolic resin (solid content) added is preferably 1000 mg, more preferably 200 mg, with respect to 1 L of wet coating booth circulating water. Moreover, the addition amount of the phenol-based resin (solid content) is preferably 0.1% by mass or more, and more preferably 0.5% by mass or more, with respect to the paint (solid content) in the circulating water. Moreover, the upper limit of the addition amount of the phenolic resin (solid content) is preferably 100% by mass, more preferably 10% by mass with respect to the paint (solid content) in the circulating water. The phenolic resin is suitable for water treatment in circulating water having a large amount of surface foam trapping an aqueous coating material or circulating water capturing an organic solvent coating material having almost zero surface potential.

The carboxylic acid polymer employed as the tackifier is a homopolymer of an ethylenically unsaturated carboxylic acid or a copolymer of an ethylenically unsaturated carboxylic acid and another monomer. Examples of the ethylenically unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid. Examples of the monomer copolymerizable with the ethylenically unsaturated carboxylic acid include acrylamide, methacrylamide, acrylic ester, methacrylic ester, and styrene. The weight average molecular weight of the carboxylic acid polymer is preferably 4 to 1,000,000.
Among the carboxylic acid polymers, a maleic acid polymer is preferable from the viewpoint of tack-free performance. The maleic acid polymer is a homopolymer of maleic acid or a copolymer of maleic acid and another monomer. The weight average molecular weight of the maleic acid polymer is preferably 4 to 500,000. You may use a maleic acid type polymer individually by 1 type or in combination of 2 or more types.
The addition amount of the carboxylic acid polymer (solid content) is preferably 0.01 mg or more, and preferably 0.1 to 1,000 mg with respect to 1 L of the wet coating booth circulating water. Moreover, the addition amount of the carboxylic acid polymer (solid content) is preferably 0.01 to 300% by mass, more preferably 0.05 to 10% by mass with respect to the paint (solid content) in the circulating water. . The carboxylic acid-based polymer is not particularly limited in its form, and can be, for example, an aqueous solution, suspension, emulsion, powder, or the like.

  The coagulant used in the present invention has an action of neutralizing the charge of fine particles in water (for example, suspended fine particles of an uncoated paint that has been tackified) to form fine flocs. The coagulant is roughly classified into an organic coagulant and an inorganic coagulant. In the present invention, inorganic coagulants are preferably used, and aluminum coagulants are more preferably used.

Organic coagulants include sodium alginate; chitin / chitosan coagulants; biocoagulants such as TKF04 and BF04; polyethyleneimine, cation-modified polyacrylamide, polyamine, polyamine sulfone, polyamide, polyalkylene polyamine, amine cross-linked polycondensation Dimethylaminoethyl acrylate, dimethyldiallylammonium chloride polymer (DADMAC), polycondensate of alkylamine and epichlorohydrin, polycondensate of alkylene dichloride and polyalkylenepolyamine, polycondensate of dicyandiamide and formalin, DAM (dimethylaminoethyl methacrylate homopolymer or copolymer), polyvinylamidine, copolymer of diallyldimethylammonium chloride and acrylamide, melamine and alcohol Can be mentioned polycondensates of hydrate, polycondensates of dicyandiamide and an aldehyde, a cationic polymer coagulant such as polycondensate of dicyandiamide and diethylenetriamine. Examples of the alkylamine in the polycondensate of alkylamine and epichlorohydrin include monomethylamine, monoethylamine, dimethylamine, and diethylamine. Examples of the aldehyde in the melamine / aldehyde condensate and the dicyandiamide / aldehyde polycondensate include formaldehyde, acetaldehyde, propionaldehyde, paraformaldehyde which is a trimer of formaldehyde. A commercially available product can be used as the organic coagulant. For example, the cationic polymer coagulant preferably has a weight average molecular weight of 1,000 to 1,000,000, more preferably 5,000 to 300,000. These organic coagulants may be used alone or in combination of two or more.
The amount of the organic coagulant (solid content) added is preferably 100 mg or less, preferably 30 mg or less, with respect to 1 L of wet coating booth circulating water. Moreover, the addition amount of the organic coagulant (solid content) is preferably 10% by mass or less, more preferably 2% by mass or less with respect to the paint (solid content) in the circulating water.

  Examples of inorganic coagulants include aluminum coagulants such as aluminum sulfate (sulfate band), polyaluminum chloride (PAC), aluminum chloride, basic aluminum chloride, pseudoboehmite alumina sol (AlO (OH)); ferrous hydroxide, Iron salt coagulants such as ferrous sulfate, ferric chloride, polyferric sulfate, iron-silica inorganic polymer coagulants; zinc coagulants such as zinc chloride; activated silicic acid, polysilica iron coagulants, etc. Can be mentioned. Of these, aluminum-based coagulants are preferred. These inorganic coagulants may be used alone or in combination of two or more.

The amount of the inorganic coagulant (solid content, in the case of an aluminum-based coagulant, converted to Al ₂ O ₃ ) is preferably 5 mg or more, preferably 10 to 30 mg with respect to 1 L of the wet coating booth circulating water. In addition, the amount of the inorganic coagulant (solid content, in the case of an aluminum-based coagulant, converted to Al ₂ O ₃ ) is preferably 0.5 to 10% by mass with respect to the paint (solid content) in the circulating water. Preferably it is 1.5-5 mass%.

  The organic coagulant and the inorganic coagulant are not particularly limited in the form, and can be in the form of, for example, an aqueous solution, a suspension, or an emulsion.

  From the viewpoint of facilitating sedimentation separation and centrifugation, it is preferable to form a coarse floc by aggregating the solidified floc of the uncoated paint obtained by the action of the coagulant. In the present invention, a polymer flocculant can be further added to the circulating water in order to form coarse floc. Examples of the polymer flocculant used in the present invention include those composed of an anionic polymer, a cationic polymer, an amphoteric polymer and the like. The polymer has a weight average molecular weight of preferably more than 1 million, more preferably 5 million or more.

  Examples of the polymer flocculant made of an anionic polymer include sodium polyacrylate, polyacrylic acid soda amide derivative, polyacrylamide partial hydrolyzate, partially sulfomethylated polyacrylamide, and poly (2-acrylamide) -2-methylpropanesulfuric acid. A salt etc. can be mentioned. As the anionic polymer, those having an anionization degree of 10 to 30 mol% are suitable. The weight average molecular weight of the anionic polymer is preferably 8 million to 15 million. The addition amount of the anionic polymer is preferably 0.1 to 10% by mass, more preferably 0.2 to 3% by mass with respect to the uncoated paint (solid content).

  As the polymer flocculant comprising a cationic polymer, a polymer having a cationic structural unit derived from a quaternary ammonium salt of (meth) acrylic acid ester (for example, acrylamide / [2- (acryloyloxy) ethyl] benzyldimethylammonium) Copolymer of chloride / [2- (acryloyloxy) ethyl] trimethylammonium chloride, Copolymerization of acrylamide / [3- (acryloyloxy) propyl] benzyldimethylammonium chloride / [2- (acryloyloxy) ethyl] trimethylammonium chloride Polymer, acrylamide / [2- (acryloyloxy) ethyl] benzyldimethylammonium chloride / [3- (acryloyloxy) propyl] trimethylammonium chloride copolymer, acrylic / [3- (acryloyloxy) propyl] benzyldimethylammonium chloride / [3- (acryloyloxy) propyl] trimethylammonium chloride copolymer), polyaminoalkyl acrylate, polyaminoalkyl methacrylate, polyethyleneimine, polydiallylammonium halide , Chitosan, urea-formalin resin and the like. The weight average molecular weight of the cationic polymer is preferably 6 million or more, more preferably 7 million to 11 million. The addition amount of the cationic polymer is preferably 0.1 to 10% by mass, more preferably 0.2 to 3% by mass with respect to the uncoated paint (solid content).

  Examples of the polymer flocculant made of an amphoteric polymer include a copolymer of (meth) acrylamide, quaternary ammonium alkyl (meth) acrylate and sodium (meth) acrylate. The anionic / cationic molar ratio of the amphoteric polymer is preferably 0.2 to 2.0. The weight average molecular weight of the amphoteric polymer is preferably about 8 million to 10 million. The addition amount is preferably 0.1 to 10% by mass, more preferably 0.2 to 3% by mass, based on the uncoated paint (solid content).

  These polymer flocculants can be used alone or in combination of two or more. Examples of combinations used include, for example, a combination of a cationic polymer flocculant and an anionic polymer flocculant, a combination of a cationic polymer flocculant and an amphoteric polymer flocculant, and an anionic polymer flocculant and an amphoteric. A combination with a polymer flocculant is included.

  The addition amount of the polymer flocculant is normally as described above, but can be appropriately adjusted according to the formation state of the coarse floc. The amount of the polymer flocculant added is, for example, preferably 0.001 to 1 meq / L, more preferably 0.002 to 0.5 meq / L, as a colloid equivalent value with respect to circulating water.

  The wet paint booth to which the wet paint booth circulating water treatment agent of the present invention can be applied is not particularly limited in its form, and may be a dispersion type or a floating type.

  The wet coating booth circulating water treatment method according to the present invention includes adding a water treatment agent containing a cationic ST copolymer to the circulating water.

The wet paint booth circulating water treatment apparatus usually has at least the water tank 8, the paint booth 1, and the pipes A and B that connect the water tank 8 and the paint booth 1 so as to circulate. Furthermore, the wet coating booth circulating water treatment apparatus may have the solid-liquid separator 9 and pipes C and D that connect the water tank 8 and the solid-liquid separator 9 so as to circulate.
When the solid-liquid separator 9 and the pipes C and D are provided, they are supplied from the water tank 8 through the pipe A to the painting booth 1, and the uncoated paint is collected at the painting booth 1, and then passed through the pipe B. The first circulating path of the circulating water returned to the water tank 8 and the solid liquid separation apparatus 9 is supplied from the water tank 8 through the pipe C and separated from the solid by the solid liquid separation apparatus 9, and then the pipe And at least a second circulation path of circulating water returned to the water tank 8 through D (see FIG. 6). The addition of the water treatment agent to the circulating water is performed at least in one of the first circulation paths, specifically, at least one of the painting booth 1, the water tank 8, and the pipes A and B connecting them. It is preferable to carry out in place. When the solid-liquid separator 9 and the pipes C and D are provided, at least one place in the first circulation path and the second circulation path, specifically, the coating booth 1, the water tank 8, the solid-liquid separation apparatus 9, In addition, it is preferable to carry out at at least one of the pipes A, B, C and D connecting them.

  In the water treatment method according to the present invention, the water treatment agent is directly added to the circulating water stored in the water tank 8 or installed in the suction side line of the pump P used for liquid feeding from the water tank 8 to the painting booth 1. The water treatment agent is added to the circulating water through the supply port (not shown), or the water treatment agent is circulated through the supply port (not shown) installed in the liquid feed line from the water tank 8 to the solid-liquid separator 9. More preferably, it is added to water.

  In the water treatment method according to the present invention, the addition amount of the wet paint booth circulating water treatment agent and other chemicals of the present invention is typically as described above, but the agglomerated state of the unpainted paint, the sludge floating It can be appropriately adjusted according to the state and the like. In addition, since the wet paint booth circulating water treatment agent and other chemicals of the present invention are discharged out of the system together with the sludge in the sludge separation step, it is preferable to appropriately replenish the amount corresponding to this.

  The sludge generated by the above method is separated and removed from the circulating water by a known solid-liquid separation method. Examples of the solid-liquid separation method include floating separation, wedge wire, rotary screen, bar screen, cyclone, centrifuge, and filtration device. The separated and collected sludge is dewatered by gravity dehydration or the like and then incinerated or disposed of in landfill. In this way, water circulated through the wet painting booth can be removed.

  Next, an Example is shown and this invention is demonstrated more concretely. However, the following examples show only one embodiment of the present invention, and the present invention is not limited to the following examples.

Abbreviations and physical properties of water treatment agents and the like used in this example are as follows.
DAM / ST: Copolymer of 2-methacryloyloxyethyltrimethylammonium chloride and styrene (CAS No.34031-59-9), [η] = 0.25 dL / g in a 0.2N saline solution at 25 ° C. Copolymerization ratio of 2-methacryloyloxyethyltrimethylammonium chloride and styrene 85/15 (mol ratio)
DAM-Bzl: homopolymer of benzyl [2- (methacryloyloxy) ethyl] dimethylammonium chloride (CAS No. 28214-37-1), weight average molecular weight 50,000 DADMAC: homopolymer of dimethyldiallylammonium chloride (CAS No. 26062-79-3), weight average molecular weight 200,000 PAC: polyaluminum chloride DA / ECH: alkylamine / epichlorohydrin condensate (CAS No.25988-97-0), weight average molecular weight 100,000 cationic polymer flocculant : Copolymer of 2-acryloyloxyethyltrimethylammonium chloride and acrylamide (CAS No.69418-26-4), Copolymerization ratio of 2-acryloyloxyethyltrimethylammonium chloride and acrylamide 90/10 (mol ratio), Weight average molecular weight 8 million Anionic polymer flocculant: sodium acrylate Copolymer of styrene and acrylamide (CAS No. 25085-02-3), copolymerization ratio of sodium acrylate and acrylamide 20/80 (mol ratio), weight average molecular weight 10 million

Example 1 (Floatability evaluation)
To a 500 cc plastic bottle, 300 cc of water and 0.6 cc of paint (aqueous base paint for automobile bodies: silver solid content 20% by mass) were added and shaken lightly to be uniform. A predetermined amount of a water treatment agent (DAM / ST) was added thereto, and reciprocal shaking was performed 60 times / 30 seconds.
All of the reciprocally shaken liquid was poured into a 500 cc beaker. The turbidity at the bottom was measured after 1 minute from the injection. The result is shown in FIG. The amount of water treatment agent required for charge neutralization (in terms of solid content) was 6.0% by mass (based on the solid content of the paint), and the bottom turbidity during charge neutralization was 88.3.
The solution was then passed through Whatman No. It filtered with 41 and measured the turbidity of filtered water. The result is shown in FIG.

Comparative Examples 1-4
The turbidity of the bottom and filtered water was measured in the same manner as in Example 1 except that the water treatment agent (DAM / ST) was changed to that shown in Table 1. The results are shown in FIGS. 1 and 2 and Table 1.

  The turbidity of the bottom of water treated with PAC is high (FIG. 1), and the turbidity of filtered water is low (FIG. 2). From this, it can be seen that PAC has a strong aggregating action but a weak floating action. Further, it can be seen that polymers having hydrophobic groups such as DAM / ST and DAM-Bzl have low turbidity during charge neutralization unlike DADMAC, DA / ECH, and PAC.

Example 2
To a 500 cc plastic bottle, 300 cc of water and 0.6 cc of paint (aqueous base paint for automobile bodies: silver, solid content 20% by mass) were added and shaken lightly to be uniform. A predetermined amount of a water treatment agent (aqueous liquid product containing 19.2% by mass of PAC in terms of Al ₂ O ₃ and 8% by mass of DAM / ST in terms of solids) was added thereto, and reciprocated at 60 times / 30 seconds. Shake.
All of the reciprocally shaken liquid was poured into a 500 cc beaker. The turbidity at the bottom was measured after 1 minute from the injection. The result is shown in FIG. The amount of water treatment agent required for charge neutralization (active ingredient addition amount, that is, the total addition amount of PAC in terms of Al ₂ O ₃ and DAM / ST in terms of solid content) is 3.4 masses. % (Vs. solid content of paint), bottom turbidity at the time of charge neutralization was 26.0.
The solution was then passed through Whatman No. It filtered with 41 and measured the turbidity of filtered water. The result is shown in FIG.

Comparative Example 5
19 water treatment agent (PAC the terms of Al ₂ O ₃ 19.2% by mass of DAM / ST an aqueous liquid product containing 8% by weight solids basis) water treatment agent (PAC terms of Al ₂ O _3. The turbidity of the bottom and filtered water was measured in the same manner as in Example 2 except that it was changed to 2% by mass and an aqueous liquid product containing 10% by mass of DA / ECH in terms of solids. The results are shown in FIGS. 3 and 4 and Table 2. Addition amount of water treatment agent required for charge neutralization (total addition amount of active ingredient, that is, addition amount of PAC in terms of Al ₂ O ₃ and addition amount in terms of solid content of DA / ECH) is 3.7 mass. % (Vs. solid content of paint), and the bottom turbidity at the time of charge neutralization was 49.7.

Comparative Example 6
19 water treatment agent (PAC the terms of Al ₂ O ₃ 19.2% by mass of DAM / ST an aqueous liquid product containing 8% by weight solids basis) water treatment agent (PAC terms of Al ₂ O _3. An aqueous liquid product containing 2% by mass and DAM-Bzl in an amount of 4.8% by mass in terms of solid content) was changed by the same method as in Example 2, but PAC and DAM-Bzl were mixed. Evaluation was not possible because a white precipitate was formed.

  The turbidity at the bottom of water treated with a mixture of PAC and DAM / ST is significantly lower than the turbidity at the bottom of water treated with PAC alone or DAM / ST alone. It can be seen that the mixture of PAC and DAM / ST has a higher flying effect than PAC alone or DAM / ST alone. In addition, when a mixture of PAC and DAM / ST is used, the amount of the active ingredient required for charge neutralization can be reduced from 6% by mass to 3.4% by mass.

Example 3
To a 500 cc plastic bottle, 300 cc of water and 0.6 cc of paint (aqueous base paint for automobile body: silver, solid content 20% by mass) were added and shaken lightly to be uniform. A water treatment agent (aqueous liquid product containing 19.2% by mass of PAC in terms of Al ₂ O ₃ and 8% by mass of DAM / ST in terms of solid matter) was added to this by 3.4% by mass (in terms of the amount of active ingredient added). Paint solid content) was added and shaken back and forth at 30 times / 15 seconds.
Then, the plastic bottle was left still. To this, 1.0% by mass of an anionic polymer flocculant (based on the solid content of the paint) was added and shaken back and forth at 30 times / 15 seconds.
All of the reciprocally shaken liquid was poured into a 500 cc beaker. The turbidity at the bottom was measured after 1 minute from the injection. The solution was then passed through Whatman No. It filtered with 41 and measured the turbidity of filtered water. Table 3 shows the measurement results of the turbidity of the bottom and filtered water.

Example 4
The turbidity of the bottom and filtered water was measured in the same manner as in Example 3 except that the addition amount of the anionic polymer flocculant was changed to 2.0% by mass (based on the solid content of the paint). Table 3 shows the results.

Example 5
The turbidity of the bottom and filtered water was measured in the same manner as in Example 3 except that the anionic polymer flocculant was changed to the cationic polymer flocculant. Table 3 shows the results.

Example 6
The turbidity of the bottom and filtered water was measured in the same manner as in Example 5 except that the addition amount of the cationic polymer flocculant was changed to 2.0% by mass (with respect to the paint). Table 3 shows the results.

Example 7
Instead of adding 1.0% by weight of the anionic polymer flocculant, 1.0% by weight of the anionic polymer flocculant (based on the solid content of the paint) and 1.0% by weight of the cationic polymer flocculant (based on the solid content of the paint) ) And the turbidity of the bottom and filtered water were measured in the same manner as in Example 3. Table 3 shows the results.

Example 8
Instead of adding 1.0% by weight of the anionic polymer flocculant, 1.0% by weight of the anionic polymer flocculant (based on the solid content of the paint) and 2.0% by weight of the cationic polymer flocculant (based on the solid content of the paint) ) And the turbidity of the bottom and filtered water were measured in the same manner as in Example 3. Table 3 shows the results.

Example 9
Instead of adding 1.0% by weight of the anionic polymer flocculant, 2.0% by weight of the anionic polymer flocculant (based on the solid content of the paint) and 1.0% by weight of the cationic polymer flocculant (based on the solid content of the paint) ) And the turbidity of the bottom and filtered water were measured in the same manner as in Example 3. Table 3 shows the results.

  The addition of either a cationic polymer flocculant or an anionic polymer flocculant increases the floc diameter, thus reducing the filtration turbidity. Furthermore, the combined use of the cationic polymer flocculant and the anionic polymer flocculant further lowered the filtration turbidity and lowered the bottom turbidity (improving the floating property).

(Test equipment)
The test apparatus shown in FIG. 5 is provided with a paint spray gun S on the top so that paint can be sprayed at 10 g / min. Circulating water is stored in a pit (water tank: total volume of 50 L) 5, the circulating water is pumped up at 100 L / min by the pump P, and the circulating water is flown in a curtain shape on the water curtain plate 4 and returned to the pit. Can do. A treating agent, a coagulant, or a polymer flocculant can be added to the circulating water at the treating agent supply unit 6. Further, the exhaust fan F can suck out volatile components such as solvent vapor from the booth.

Example 10
The following tests were conducted using the test apparatus shown in FIG.
While pumping circulating water at 100 L / min with pump P, water treatment agent (DAM / ST) is added to circulating water at treatment agent supply unit 6 to 8 mg / L and solvent paint (two-component curable paint for automobiles) The solid content was sprayed at 10 g / min using a spray gun S.
When the operation was continued for 2 minutes, the test apparatus was stopped. The sludge that floated on the water surface of the pit was collected, and the collected sludge was touched with a finger, and the tactile sensation was classified according to the following criteria to determine whether the tackiness was good. Moreover, the turbidity of the circulating water at the bottom of the pit was measured.
The results are shown in Table 4.

(Adhesion evaluation criteria)
◎ Very good to touch, does not adhere even when rubbed with fingers ○ Very good to touch, hardens when rubbed with fingers ○ △ Slightly sticky when rubbed with fingers △ Adhesive residue × Highly sticky

Example 11
The test was conducted in the same manner as in Example 10 except that the amount of water treatment agent (DAM / ST) added was changed to 40 mg / L. The results are shown in Table 4.

Example 12
Instead of adding water treatment agent (DAM / ST) 8 mg / L, water treatment agent (DAM / ST) 6 mg / L and phenol resin alkali solution (anionic agent) 50 mg-solid content / L were added. The test was performed in the same manner as in Example 10. The results are shown in Table 4.

Example 13
Instead of adding water treatment agent (DAM / ST) 8 mg / L, water treatment agent (DAM / ST) 8 mg / L and phenol resin alkali solution (anionic agent) 65 mg-solid content / L were added. The test was performed in the same manner as in Example 10. The results are shown in Table 4.

Comparative Example 7
It tested by the same method as Example 10 except having added 50 mg-solid content / L of the alkaline solution (anionic agent) of the phenol resin instead of adding 8 mg / L of water treatment agents (DAM / ST). The results are shown in Table 4.

Comparative Example 8
It tested by the same method as Example 10 except having added 10 mg / L of water treatment agents (DA / ECH) instead of adding 8 mg / L of water treatment agents (DAM / ST). The results are shown in Table 4.

Comparative Example 9
It tested by the same method as Example 10 except having added 50 mg / L of water treatment agents (DA / ECH) instead of adding 8 mg / L of water treatment agents (DAM / ST). The results are shown in Table 4.

Comparative Example 10
Instead of adding water treatment agent (DAM / ST) 8 mg / L, water treatment agent (DA / ECH) 7.5 mg / L and phenol resin alkali solution (anionic agent) 50 mg-solid content / L were added. The test was performed in the same manner as in Example 10 except that. The results are shown in Table 4.

Comparative Example 11
Instead of adding 8 mg / L of water treatment agent (DAM / ST), 10 mg / L of water treatment agent (DA / ECH) and 65 mg of an alkaline solution of phenol resin (anionic agent) -solid content / L were added. The test was performed in the same manner as in Example 10. The results are shown in Table 4.

  Sludge can be made non-tacky by using DAM / ST in combination with a known non-tacking agent such as a phenol resin. When DAM / ST is added, even if the degree of tackiness is the same, the turbidity is lower than when DA / ECH is added. This is because the addition of DAM / ST in the solvent paint improved the sludge floatability. When only DAM / ST is added, the degree of tackiness is high. In addition, when only DAM / ST or DA / ECH is added, the turbidity is low because the paint is hardened and not dispersed at all in water.

S: Paint spray F: Exhaust fan P: Circulating water pump 1: Painting booth 2: Intake 3: Exhaust 4: Water curtain 5: Pit 6: Treatment agent supply unit 7: Foaming shower 8: Circulating water pit (water tank)
9: Solid-liquid separator 10: Concentration bowl 11: Filter

Claims (8)

Existence of the structural unit derived from the monomer represented by the formula (A) within a range of 10 to 90 mol% and a ratio that makes the function of facilitating the generation of agglomerated flocs due to the interparticle attractive force of the uncoated paint exist. and and containing a copolymer comprising a structural unit derived from styrene is and attached air bubbles in the range of 10 to 90 mole percent at a rate to function an effect of improving the flying characteristics of the sludge, the sludge Wet paint booth circulating water treatment agent for imparting floatability to water.

(In formula (A),
R ¹ is a hydrogen atom or a methyl group,
R ² and R ³ are each independently an alkyl group having 1 to 4 carbon atoms,
R ⁴ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a benzyl group,
Y is O or NH;
n represents the number of repetitions in parentheses and is an integer of 2 to 5,
Z ⁻ is a counter anion. )   The wet paint booth circulating water treatment agent according to claim 1, wherein the counter anion is a halogen ion, a sulfate ion, a phosphate ion, a borate ion or an organic acid anion.   The wet paint booth circulating water treatment agent according to claim 1 or 2, further comprising an inorganic coagulant.   The processing method of wet paint booth circulating water including adding the water treatment agent as described in any one of Claims 1-3 to circulating water.   The treatment of circulating water in a wet coating booth according to claim 4, wherein the addition of the water treatment agent to the circulating water is performed in at least one of a coating booth, a water tank, a solid-liquid separator, and a pipe connecting them. Method.   The wet paint booth circulating water treatment method according to claim 4 or 5, further comprising adding a tackifier to the circulating water.   The method for treating circulating water in a wet paint booth according to any one of claims 4 to 6, further comprising adding a coagulant to the circulating water.   The method for treating wet paint booth circulating water according to any one of claims 4 to 7, further comprising adding a polymer flocculant to the circulating water.

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