JPH057878A - Treatment of waste water containing coating material - Google Patents

Abstract

PURPOSE:To provide the method for treating a waste water containing a coating material by which, when a small amt. of a treating agent is used, a coating material of any kind remaining in the waste water can be flocculated to have low cohesion property and good dispersibility and can easily be separated and removed from the waste water. CONSTITUTION:A coating material not deposited but remaining in waste water is removed by using a treating agent. This treating agent used contains a cation- type water soluble resin as the effective component comprising the reactional product of polyalkylene glycolpolyhalohydrin ether and aziridine compd. and/or polyamine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating wastewater containing paint, and more particularly to a method for treating circulating water in a wet coating booth.

[0002]

2. Description of the Related Art Conventionally, there are a dry method booth and a wet method booth in a coating booth, and these have different treatment methods for collecting uncoated paint mist. For example, in the wet method, the paint mist is collected and removed by washing water. This wet method is mainly used in large-scale painting booths.

The paints used in this coating booth include oil-based (oil-soluble) paints and water-based (water-soluble) paints. In particular, in recent years, the use of water-based paints has been increasing in coating lines. This is to avoid the use of organic solvents as air pollution, resource saving and safety measures.
However, in a wet booth using an aqueous paint, it is more difficult to separate and remove the uncoated paint from the circulating water, as compared with the case of using an oil paint. The uncoated mist of water-based paint is
It dissolves in the coating booth circulating water, and as a result, the transparency of the circulating water decreases and the COD (chemical oxygen demand) becomes very large. For this reason, in a wet booth using an aqueous paint, use of the aqueous paint becomes difficult unless an effective solid-liquid separation technique is established.

A coagulation method is generally used as a solid-liquid separation method for circulating water in a wet booth using an aqueous paint. In this aggregating method, generally, the following various inorganic aggregating agents are used, or this inorganic aggregating agent and a polymer aggregating agent such as polyaminoethyl (meth) acrylate and its quaternary salt, sodium polyacrylate, polyacrylamide, etc. By combining with, the uncoated paint mist is aggregated,
Form large flocs that tend to settle or float,
The method of separating and removing this floc from circulating water is adopted. In the wet booth, the obtained treated water is reused as circulating water in the coating booth. Examples of the inorganic aggregating agent used in such an aggregating method include water-soluble salts such as sulfuric acid band, aluminum chloride, polyaluminum chloride, ferric chloride, zinc chloride and zinc sulfate.

[0005]

However, the above-mentioned inorganic coagulant contains a large amount of corrosive chlorine ions and sulfate ions, and these ions remain in the treated water after the coagulating precipitation treatment. Therefore, when the coating booth circulation system is non-blowing, or when the blowdown amount is extremely small, the concentration of the corrosive ions in the circulating water gradually increases, and as a result, for example, mist such as a coating booth duct is generated. There was a problem that the upper part of the booth to be touched might be corroded.

Therefore, a method of using a cationic polymer compound having a low corrosive property such as polyaminoethyl (meth) acrylate and its quaternary salt and polyethyleneimine as a treating agent without using the above-mentioned inorganic coagulant has been investigated. However, these polymers do not necessarily have good coagulation performance, the flocs produced by coagulation are soft and have strong adhesiveness, so paint slag easily sticks to the coating booth, less effective at low concentrations, When the type of paint changes, there is a problem that its cohesiveness changes greatly.

In view of such circumstances, the present invention solves the above-mentioned problems of the conventional method and promptly insolubilizes and agglomerates the uncoated paint in the paint-containing wastewater, resulting in low tackiness and dispersibility. A good floc is formed, which makes it possible to prevent paint slag from adhering to the coating booth, and it is possible to easily separate and remove the uncoated paint from the wastewater. It is an object of the present invention to provide a method for treating paint-containing wastewater whose effect is large even if it is low, and its cohesiveness hardly changes even if the type of the target paint changes.

[0008]

In order to solve the above-mentioned problems, a method for treating paint-containing wastewater according to the present invention is a paint-containing wastewater for removing uncoated paint in paint-containing wastewater by using a treating agent. In the treatment method according to item 1, the treatment agent contains a cationic water-soluble resin obtained by reacting a polyalkylene glycol polyhalohydrin ether with an aziridine compound and / or a polyamine as an active ingredient. And

The polyalkylene glycol polyhalohydrin ether used in the present invention can be obtained, for example, by reacting polyalkylene glycol and epihalohydrin. Examples of the polyalkylene glycol used in producing the polyalkylene glycol polyhalohydrin ether in this manner include polyethylene glycol, polypropylene glycol, ethylene glycol / propylene glycol copolymer, and the like, but are not particularly limited. However, the use of polyethylene glycol is particularly preferred. The molecular weight of these polyalkylene glycols is not particularly limited, but is preferably in the range of 200 to 100,000, more preferably 600 to 50,000,
Most preferably, it is in the range of 1,000 to 20,000. This is because if a resin having a molecular weight of less than 200 is used, gelation is likely to occur during the production of a cationic water-soluble resin which will be described in detail later, while a resin having a molecular weight of more than 100,000 is used. In that case, the reactivity with epihalohydrin becomes low, and the desired cationic water-soluble resin may not be obtained.

The epihalohydrin used to obtain the polyalkylene glycol polyhalohydrin ether by reacting with the above polyalkylene glycol includes:
It is not particularly limited, and examples thereof include epichlorohydrin, epibromhydrin, and the like, but epichlorohydrin is preferably used from the viewpoint of industrial availability. The specific method for reacting the polyalkylene glycol and epihalohydrin described above to obtain the polyalkylene glycol polyhalohydrin ether is not particularly limited, but for example, Bronsted acid or Lewis acid Is used as a catalyst, and a method of reacting a polyalkylene glycol with epihalohydrin at 30 to 150 ° C., preferably 50 to 100 ° C. can be mentioned.

The Bronsted acid or Lewis acid which can be used in such a method is not particularly limited, but examples thereof include sulfuric acid, p-toluenesulfonic acid, perchloric acid, aluminum chloride and boron fluoride ether complex. . Among these, boron fluoride ether complex is particularly preferable. The amount of these catalysts used is not particularly limited, but is, for example, 0.01 to 1% by weight, and preferably 0.02 to 1% by weight based on the polyalkylene glycol.
It is 0.5% by weight.

The ratio of polyalkylene glycol to epihalohydrin is not particularly limited, but for example, the amount of epihalohydrin is 1 to 10 mol per mol of polyalkylene glycol, and 2 is preferable.
-5 mol is more preferable. This is because when the proportion of epihalohydrin used is less than 1 mol, unreacted polyalkylene glycol remains, the desired cationic water-soluble resin described in detail later cannot be obtained, and the performance as a treating agent is insufficient. This is because there is a risk that it will be If the proportion of epihalohydrin used exceeds 10 moles, gelation tends to occur during the production of the cationic water-soluble resin, which is not suitable.

The cationic water-soluble resin used in the present invention is, as described above, an aziridine compound and / or a polyalkylene glycol polyhalohydrin ether.
Alternatively, it is obtained by reacting a polyamine. For example, it is obtained by adding the aziridine compound to the polyalkylene glycol polyhalohydrin ether or the aqueous solution thereof obtained as described above and conducting the ring-opening addition polymerization reaction.

The aziridine compound that can be used is not particularly limited as long as it has one aziridine group (aziridinyl group) in the molecule. For example, those having a substituent on the aziridine ring may be used, or two or more aziridine compounds may be used. Specific examples of such an aziridine compound include, but are not particularly limited to, ethyleneimine, propyleneimine, alkyleneimine such as butyleneimine, N-hydroxyethylethyleneimine, N-cyanoethylethyleneimine, N-methylethyleneimine, N
-Ethylethyleneimine, N-phenylethyleneimine, N-acetylethyleneimine, N-methacryloylaziridine, β-aziridinylmethylpropionate,
β-aziridinylethyl methacrylate and the like can be mentioned. Among these, alkyleneimine is preferable, and ethyleneimine is more preferable, in view of economic advantages and reactivity with polyalkylene glycol polyhalohydrin ether.

The amount of the aziridine compound used (however, the total amount when two or more kinds are used) is not particularly limited, but for example, with respect to 100 parts by weight of the polyalkylene glycol polyhalohydrin ether, the aziridine compound 10 to 10 parts by weight is used. 10,000 parts by weight is preferred, 30 to 10
00 parts by weight is more preferred. This is because when the ratio of the aziridine compound used is less than 10 parts by weight, the performance of the treating agent using the obtained resin is insufficient, and when it exceeds 10,000 parts by weight, it is economically disadvantageous. Because. The reaction conditions are not particularly limited, but for example, the final concentration of the resulting cationic water-soluble resin is 5 to 5.
It is preferable to prepare a 100% by weight aqueous solution,
It is more preferable to use an aqueous solution of 10 to 70% by weight. This is because the reaction becomes slow in an aqueous solution having a final concentration of less than 5% by weight. The reaction temperature is not particularly limited, but is usually a temperature at which an aziridine compound is subjected to a ring-opening polymerization reaction, for example, a temperature in the range of 0 to 200 ° C. is preferable, and a range of 50 to 100 ° C. is more preferable. This is because when the reaction temperature is lower than 0 ° C, the reaction rate becomes slow, while when the reaction temperature exceeds 200 ° C,
This is because it becomes difficult to control the reaction.

Further, the cationic water-soluble resin used in the present invention may be obtained by carrying out an addition reaction by using polyamine instead of the aziridine compound. The polyamine that can be used is not particularly limited as long as it has two or more amino groups in the molecule. For example, one kind of polyalkylene polyamine, polyamide polyamine, a reaction product of a polyamide polyamine and an aziridine compound, etc. Alternatively, two or more kinds may be mentioned.

The amount of these polyamines used (however, 2
The total amount when more than one kind is used) is the same as the above-mentioned amount of the aziridine compound used when the aziridine compound is used. Further, the cationic water-soluble resin used in the present invention may be obtained by using an aziridine compound and a polyamine in combination. In this case, the total amount of the aziridine compound and polyamine used is the same as the amount of the aziridine compound used when the aziridine compound is used alone.

The cationic water-soluble resin obtained by the above-mentioned method can be adjusted to have a wide range of molecular weights, for example, 1,000 to 2,000,000, preferably 5,000 to 1,000,000. is there. As described above, the treating agent used in the present invention contains the cationic water-soluble resin as an active ingredient.

The amount of the treating agent used is appropriately determined depending on the properties of the waste water containing the coating material to be treated, and is not particularly limited, but usually, with respect to the uncoated paint in the waste water containing the coating material,
The amount of the cationic water-soluble resin is in the range of 0.1 to 100% by weight, and preferably 1 to 50% by weight. In addition, if necessary, in order to further reduce the tackiness of the flock of the uncoated paint, polyvinyl alcohol, methylolated melamine, nonionic polymer compounds such as polyacrylamide, sodium polyacrylate, anion-modified 1 selected from the group consisting of anionic polymer compounds such as polyacrylamide
You may use together 1 type or 2 or more types of high molecular compounds as an active ingredient of a treating agent.

Further, if necessary, it is possible to use a conventionally used treating agent, for example, one or more of water-soluble salts such as iron, aluminum and zinc and hydroxides. is there. Such water-soluble salts and hydroxides are not particularly limited, but include, for example, sulfuric acid band, aluminum chloride, polyaluminum chloride, ferric chloride,
Zinc chloride, zinc sulfate, iron hydroxide, aluminum hydroxide,
Examples include zinc hydroxide and the like.

The above coating agent makes the uncoated coating insoluble,
The method for removing (separating and collecting) flocs generated by aggregation may be the same as the conventional method and is not particularly limited, and examples thereof include a sedimentation separation method, a floatation separation method, and a filtration method.

[0022]

[Function] Treating wastewater containing paint with a treatment agent containing a cationic water-soluble resin obtained by reacting a polyalkylene glycol polyhalohydrin ether with an aziridine compound and / or polyamine as an active ingredient In this case, the uncoated paint in the wastewater quickly becomes insoluble and aggregates to form flocs with good dispersibility that easily settle or float, and as a result, the uncoated paint is easily separated and removed from the wastewater. It will be possible. Since the flocs of this uncoated paint have low tackiness, it is difficult for the paint slag to adhere to the coating booth. Moreover, these effects are large even if the concentration of the treating agent in the waste water is low, and the cohesiveness thereof hardly changes even if the type of the target coating material changes.

[0023]

EXAMPLES Examples and comparative examples of the present invention will be shown below, but the present invention is not limited to the following examples. First,
Cationic water-soluble resins (1) to (6) for use in Examples 1 to 6 described later were produced by the following Synthesis Examples 1 to 6.

-Synthesis Example 1-1,000 g of polyethylene glycol having a molecular weight of 1800 was charged into a flask equipped with a dropping funnel, a stirrer, a thermometer and a reflux condenser, and heated to 65 ° C. After adding 2.1 g of boron trifluoride etherate as a catalyst, 113.1 g of epichlorohydrin was added dropwise over 20 minutes, and further reacted for 4.5 hours to obtain polyethylene glycol polychlorohydrin ether.

160 g of the obtained polyethylene glycol polychlorohydrin ether was added to 1,600 ion-exchanged water.
Dilute with g and heat to 80 ° C. Then, 240 g of ethyleneimine was added dropwise over 45 minutes, and the reaction was continued for 6 hours. Then, it was confirmed by gas chromatography that the residual ethyleneimine was 1 ppm or less and the viscosity of the resin was constant, and the reaction was completed to obtain a cationic water-soluble resin (1).

The concentration of the obtained cationic water-soluble resin (1) (aqueous solution) was 20% by weight, and its viscosity at 25 ° C. (by B-type rotational viscometer) was 360 cps. -Synthesis Examples 2 to 4-A cation was prepared by repeating the same operation as in Synthesis Example 1 except that the types of raw materials used in Synthesis Example 1, the amounts used, and the conditions during the reaction were as shown in Table 1 below. Water-soluble resins (2) to (4) were obtained. The viscosities (25 ° C .; measured with a B-type rotational viscometer) of these resins in a synthetic final concentration aqueous solution (resin liquid) and a concentration 20% by weight were as shown in Table 1 below.

[0027]

[Table 1]

-Synthesis Example 5-A flask similar to that of Synthesis Example 1 was charged with 65 g of polyethyleneimine having a molecular weight of 10,000, and 335 g of deionized water.
Diluted with and heated to 50 ° C. Then, 50 g of a 50 wt% aqueous solution of polyethylene glycol polychlorohydrin ether obtained in Synthesis Example 2 was added, and further 50 wt%
0.5 g of an aqueous sodium hydroxide solution was added and reacted for 2 hours to obtain a cationic water-soluble resin (5).

The concentration of the obtained cationic water-soluble resin (5) (aqueous solution) was 20% by weight, and its viscosity at 25 ° C. (by B-type rotational viscometer) was 29 cps. -Synthesis Example 6-A flask similar to that of Synthesis Example 1 was charged with 76 g of polyamide polyamine obtained by the condensation reaction of diethylenetriamine and adipic acid, and diluted with 346 g of ion-exchanged water.
Heated to 50 ° C. Then, 28 g of a 50 wt% aqueous solution of polyethylene glycol polychlorohydrin ether obtained in Synthesis Example 1 was added, 1.2 g of a 50 wt% sodium hydroxide aqueous solution was further added, and the mixture was reacted for 2 hours to obtain a cationic water-soluble resin ( 6) was obtained.

The concentration of the obtained cationic water-soluble resin (6) (aqueous solution) was 20% by weight, and its viscosity at 25 ° C. (by B-type rotational viscometer) was 175 cps.
The following Examples 1 to 6 were performed using the cationic water-soluble resins (1) to (6) obtained in the above Synthesis Examples 1 to 6. -Example 1-A water-soluble acrylic resin-based paint was diluted with tap water to give a concentration of 1
A test solution of 000 ppm was prepared. 500 ml of this test solution was placed in a beaker and used as a treating agent in the above-mentioned Synthesis Example 1.
The cationic water-soluble resin (1) obtained in (1) was added. However, the addition amount of the resin (1) at that time was such that the resin (1) was 300 ppm with respect to the test liquid before addition.

Then, using a jar tester, 150 rp
After stirring at m 2 for 2 minutes, the mixture was further stirred at 50 rpm for 3 minutes and allowed to stand for 5 minutes. Then, the agglomeration state of the paint dregs and the clarity of the supernatant liquid were examined. Regarding the clarity of the supernatant, "◎" indicates that there is almost no turbidity, "○" indicates that it is slightly turbid, and "△" indicates that it is large.
In the case where there was no difference from that before the treatment, each was evaluated by "x". The results are shown in Table 2 below.

-Examples 2 to 6-In Example 1, instead of the cationic water-soluble resin (1) as the treating agent, the cationic water-soluble resins (2) to () obtained in the above-mentioned Synthesis Examples 2 to 6 were used. In the same manner as in Example 1 except that 6) was added to the test solution in the same amount, the state of aggregation of the paint slag and the clarity of the supernatant liquid were examined. The results are shown in Table 2 below.

-Comparative Example 1-In Example 1, the agglomeration state of the paint slag and the clarity of the supernatant liquid were examined in the same manner as in Example 1 except that no treating agent was added to the test solution. The results are shown in Table 2 below. -Comparative Examples 2 to 4-Example 1 except that the same amount of the treating agent of the type shown in Table 2 below was added to the test solution instead of the cationic water-soluble resin (1). In the same manner as above, the agglomeration state of the paint dregs and the clarity of the supernatant liquid were examined. The results are shown in Table 2 below.

[0034]

[Table 2]

[0035]

According to the method for treating paint-containing wastewater according to the present invention, the uncoated paint in the wastewater has low tackiness.
Since the flocs having good dispersibility are formed, it is difficult for the paint dregs to adhere to the coating booth and the uncoated paint can be easily separated and removed from the waste water, so that a stable coating line operation is possible. Further, these effects are large even when the concentration of the treating agent in the waste water is low, and hardly change even when the type of the target coating material changes. Also wide
The effect is more remarkable in the pH range, especially in the alkaline range.

Continued front page    (72) Inventor Hideyuki Tahara             5-8 Nishiomitabicho, Suita City, Osaka Prefecture             Central Research Institute of Nippon Shokubai

Claims (3)

[Claims] 1. A method for treating paint-containing wastewater, which comprises removing a non-coated paint in paint-containing wastewater with a treating agent, wherein the treating agent is an aziridine compound and a polyalkylene glycol polyhalohydrin ether. And / or a cationic water-soluble resin obtained by reacting a polyamine as an active ingredient. 2. The total amount of aziridine compound and / or polyamine used is 10 to 10,0 per 100 parts by weight of polyalkylene glycol polyhalohydrin ether.
The method for treating paint-containing wastewater according to claim 1, wherein the amount is in the range of 00 parts by weight. 3. The method for treating paint-containing wastewater according to claim 1 or 2, wherein a nonionic and / or anionic polymer compound is used in combination as an active ingredient of the treatment agent.