JP3531645B1 - Painting booth water treatment agent and treatment method - Google Patents

Abstract

[PROBLEMS] To collect unpainted paint mist by adding a very small amount to the coating booth water from a wet coating booth or circulating water to be circulated, it is possible to prevent the generation of odors in the coating booth water and circulating water. Provided is a coating booth water treating agent capable of imparting a coating mist with a tack-free effect. SOLUTION: Hydroxylamine and a salt thereof (eg,
At least one compound selected from hydroxylamine sulfate) is added to the coating booth water or circulating water at a concentration of 0.01 to 50 g / l. The hydroxylamine compound imparts an anti-adhesive effect of paint mist and an anti-rust property to the coating booth water and circulating water in addition to the deodorant and antibacterial properties.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to treatment of coating booth water capable of effectively suppressing thinner odors emitted from wet coating booths and bad odors caused by rotting, and effectively detackifying paint mist. And a method for treating coating booth water using this treatment agent.

[0002]

2. Description of the Related Art A spray coating method of spraying a mist of a paint by using a spray gun is used for coating an object having a complicated shape such as an automobile body. In spray coating, about 30% of the paint adheres to the object to be coated on average. Therefore, when spray coating is performed, it is general that the paint that has not adhered to the object to be coated is captured by the water curtain of the wet coating booth and the uncoated paint mist is collected in water. Since the paint mist collected in water agglomerates, the paint mist agglomerated in a sludge form is separated from water as a paint lees by an appropriate solid-liquid separation method such as centrifugation. The water from which the paint residue has been removed is normally returned to the paint booth for recycling. That is, it is used as circulating water.

Conventionally, paint dregs separated from circulating water were often discarded by landfill treatment, but in recent years,
After being dried and pulverized, it is also recycled as a filler for auxiliary combustion aids, concrete aids, paints for underbody of automobiles and water-based emulsion paints for fuel tanks.

Spray paint used for automobile bodies is
Usually, it is an acrylic or urethane type baking type paint. The paint mist contained in the paint booth water is not baked and is uncured, and thus has high adhesiveness.
Therefore, there is a troublesome problem that the aggregate of the paint mist in the paint booth water adheres to the solid-liquid separation device, the circulation pump, the piping, etc., which makes it difficult to collect the paint mist and circulate the circulating water (problem 1). .

As the organic solvent contained in the general coating composition, toluene, xylene, ethyl acetate, and a large amount of ketones represented by methyl isobutyl ketone (MIBK) are used. These ketones have a solubility in water and will accumulate as the coating booth water is recycled.
Therefore, the thinners (alcohols and ketones) contained in the collected paint mist accumulate in the circulating water, which may cause thinners to be released from the paint booth water at the work site of the paint factory and its surrounding area. Annoying problems such as the deterioration of work environment and complaints from local residents are increasing due to odors (Problem 2).

By the way, the malodorous substances generated by spoilage bacteria are
Aldehydes, carboxylic acids, sulfur compounds, and nitrogen compounds contained in 22 types of specific malodorous substances specified by the Malodor Prevention Law. In particular, it is known that the above-mentioned ketones, aldehydes, carboxylic acids, sulfur compounds, and nitrogen compounds generate a bad odor at low concentrations as compared with toluene, xylene, and ethyl acetate . Therefore, at the work site of the coating plant and its surrounding area, the rotten odor (aldehydes, carboxylic acids, sulfur compounds,
(Nitrogen compounds) are also increasing the annoying problem that the working environment is pointed out by odors and complaints are received from local residents (Problem 3).

In order to solve the problem 1, a treatment agent for coating booth water has been used so far in order to make the coating mist tack-free. Examples of known treatment agents include clay minerals such as bentonite, sepiolite (special fibrous minerals), alkali agents, amphoteric metal compounds, cationic polymers, colloidal silica, etc. There is also a proposal to combine (see Patent Documents 1 to 5).

In order to solve the problems 1 and 3,
Further, a method of adding an antibacterial agent has also been proposed (see Patent Document 6). Up to now, there has been no proposal for a coating booth water treatment agent for solving the problem 2, but a treatment method for suppressing the formalin odor by applying it to a filter of an automobile air conditioner has been proposed (see Patent Document 7). .

[0009] The use of chemicals used for preventing slime generation in paper mills and the like to synthesize chemicals has only been proposed to exhibit antibacterial effects (see Patent Document 8). Thus, as a conventional coating booth water treatment agent, the substance that acts as a coagulant or an adsorbent has been mainly used, with a focus on detackifying the paint mist, so it has no odor suppressing function. In addition to the fundamental problem, there is a problem that a corrosion problem occurs, and a small amount does not show a sufficient effect, and it is not satisfactory in view of demands for severe environmental problems in the future.

[0010]

[Patent Document 1] Japanese Patent No. 2648351

[Patent Document 2] Japanese Patent Laid-Open No. 8-259896

[Patent Document 3] Japanese Patent Laid-Open No. 10-180007

[Patent Document 4] Japanese Patent Laid-Open No. 11-672

[Patent Document 5] Japanese Patent Laid-Open No. 11-77061

[Patent Document 6] JP-A-6-31281

[Patent Document 7] Japanese Patent Laid-Open No. 11-99194

[Patent Document 8] Japanese Patent Application Laid-Open No. 8-20505

[0011]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems and eliminates the thinner odor and rotten odor generated from paint booth water or circulating water by adding a small amount to the coating booth water or circulating water. A treatment agent for coating booth water or circulating water and a treatment method using the same, which can suppress, can be made non-adhesive to paint mist, and can also be provided with rust preventive property. The challenge is to provide.

Further, a treatment agent for coating booth water and circulating water capable of suppressing the odor of aldehydes, carboxylic acids, sulfur compounds and nitrogen compounds generated from the growth of ketones derived from coating thinner and spoilage bacteria, and the same. It is an object to provide a processing method using the.

[0013]

The present inventors have found that when hydroxylamine, which is both a strong reducing agent and a slow oxidant, is added to the coating booth water from a wet coating booth or circulating water, 0.5 g / The inventors have found that even a low concentration such as 1 can reduce or suppress the thinner odor and the rotten odor, and can also provide the effect of making the paint mist tack-free, and have reached the present invention.

The present invention is a treatment agent for coating booth water, which contains at least one compound selected from hydroxylamine and salts thereof.
From another aspect, the present invention is a coating booth water in a wet coating booth or a coating booth water containing a paint mist of a baking-type paint recovered from the wet coating booth (both are simply referred to as "coating booth water" for convenience). ) Contains at least one compound selected from hydroxylamine and salts thereof, the method for treating coating booth water.

In a preferred embodiment, after the paint dregs are separated and collected from the water of the coating booth after the treatment, the remaining water is circulated and used in the painting process. In other words, it is circulating water. Paint mist
It is a mist of at least one paint selected from compounds having a carbonyl group (ketone, aldehyde).

[0016] From still another aspect, the present invention provides a coating booth water or circulating water when the coating booth water or the circulating water from a wet coating booth is placed in an environment where spoilage-causing bacteria easily grow. A method for suppressing the odor of coating booth water, which comprises incorporating at least one compound selected from the salt thereof.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as a treatment agent for coating booth water in a wet coating booth or coating booth water or circulating water recovered therefrom (hereinafter, also collectively referred to as "coating booth water"), hydroxylamine and At least one compound selected from the salts thereof (hereinafter collectively referred to as hydroxylamine compound including hydroxylamine and salts thereof) is used.

Hydroxylamine is a compound represented by NH ₂ OH and has a structure in which only one hydrogen of ammonia (NH ₃ ) is oxidized to a hydroxyl group. Hydroxylamine itself is a strong reducing agent because it is easily oxidized to nitric acid via nitrous acid. However, since it is reduced to ammonia under reducing conditions, hydroxylamine also serves as a slow oxidant.

The hydroxylamine salt is a salt composed of (NH ₃ OH) ⁺ cation and acid anion. Examples of hydroxylamine salts include hydroxylamine sulfate [(NH ₃ OH) ₂ S
O _4] and hydroxylamine hydrochloride [(NH ₃ OH) Cl] are mentioned.

The hydroxylamine compound which is preferably used in the present invention is hydroxylamine sulfate in view of stability and cost of the compound. When the hydroxylamine compound is added to the coating booth water containing the paint mist, the odor of thinners having a carbonyl group in the coating booth water is significantly suppressed. In addition, the adhesiveness of paints having a carbonyl group is also reduced, and non-adhesive paint meal can be obtained after solid-liquid separation, and paint mist and its agglomerates are generated during circulation of circulating water in piping systems, circulation pumps, etc. To be adhered to.

The reason why the hydroxylamine compound suppresses the thinner odor and the reason why the paint mist is made non-tacky has not been elucidated, but hydroxylamine reacts with some reaction, particularly the well-known carbonyl oxygen of aldehydes and ketones. It is assumed that the reaction to form aldoxime or ketoxime) is involved. For example,
When the thinner is methyl isobutyl ketone (MIBK) and the paint is urethane type, it is considered that hydroxylamine reacts with the ketone group or urethane bond by the oxime reaction. An example of the reaction is shown in FIG.

Further, FIG. 2 shows the data of the gas chromatograph which confirms that these reactions are occurring, and Table 1 shows the measurement conditions of the gas chromatograph at this time.

[0023]

[Table 1]

In this experiment, 1 ml of thinner having the components shown in Table 2 below was added to 100 ml of water, mixed in a separating funnel, and allowed to stand for 15 minutes, and then the aqueous phase (lower layer) was separated.
2 is a result of comparison between a sample solution, a solution obtained by adding 0.5 g / l of hydroxylamine sulfate to this solution, and a solution prepared by adding 0.5 g / l of hydroxylamine sulfate to water.

From the results shown in FIG. 2, it was found that the thinner component produced some reaction product when hydroxylamine sulfate was added. The hydroxylamine compound exerts an antibacterial effect in addition to the above effects. Therefore, even when putrefactive bacteria are placed in an environment where they easily grow, it is possible to suppress the occurrence of putrefactive bacteria and prevent the occurrence of putrefactive odor without adding an antibacterial agent to the coating booth water. it can. In addition, it also has an anti-corrosion effect, and can also prevent the occurrence of rust in the piping system and the circulation pump.

The addition of the hydroxylamine compound to the coating booth water is carried out at a hydroxylamine compound concentration of 0.01 to
The concentration is preferably 50 g / l, more preferably 0.1 to 1 g / l. Even if the concentration of hydroxylamine compound in the coating booth water falls within the above range during the first bath, the hydroxylamine compound will be consumed by reacting with the resin and thinner components of the paint during circulation. It is preferable to supplement the coating booth water with hydroxylamine so that the concentration of the hydroxylamine compound in the coating booth water is maintained within the above range.

As described above, the addition amount of the hydroxylamine compound may be very small as compared with the conventional treating agents. The hydroxylamine compound may explode due to its strong oxidizing action at an aqueous solution concentration of 15 to 35% by mass or more, depending on the compound species, but in the present invention, it is at a very low concentration of about several% by mass at most. Good, no danger of explosion.

[0028] In the treatment agent of the present invention suppresses the thinner odor, paint the paint mist can be non viscous arrived is a baking type coating material, preferably a coating material having a carbonyl group.

In addition to the hydroxylamine compound, the water used in the coating booth water of the wet coating booth contains a treating agent which has been used in the prior art for detackifying the paint mist unless the reactivity with the hydroxylamine compound is remarkable. You may use together. Examples of such treating agents include, for example, clays, sepiolite, amphoteric metal compounds, cationic polymers, and alkaline agents. The amount of them added may be the same as in the prior art.

Further, a treating agent which has been used in the prior art for the purpose of antibacterial effect may be used in combination. Examples of such treating agents include, for example, molybdenum compounds, copper compounds, triazines, thiazolines, pyridines, morpholine,
There are phenols. The amount of them added may be the same as in the prior art.

However, in the present invention, the hydroxylamine compound alone can sufficiently obtain the antibacterial effect. The coating booth water treated with the hydroxylamine compound according to the present invention is then separated into water to be circulated and coating dregs by an appropriate solid-liquid separation means such as centrifugation as in the conventional case. Since the paint mist by the hydroxylamine compound is not tacky arrived, separated paint sludge is not sticky and is easy to handle.

The paint residue may be dried as it is and discarded by landfill, but it can also be crushed after drying and recycled as a resin. Recyclable applications include fillers such as combustion improvers, concrete aids, underbody paints for automobiles and water-based emulsion paints for fuel tanks.

[0033]

EXAMPLE (Example 1) This example confirms the effect of suppressing thinner odor.

In the experiment, 1 ml of thinner of the components shown in Table 2 was added to 100 ml of water, mixed in a separating funnel, and allowed to stand for 15 minutes, and then the aqueous layer (lower layer) was separated and used as a sample solution. Using the blank as a blank, the blank solution with each additive added was stirred under the same conditions for 1 hour, and then the odors were compared at 25 ° C. As an evaluation method, five inspectors were asked to confirm the odor of blank water and the solution to which each additive was added, and the reduction of the odor was compared.

Comparative Example 7 was evaluated by the odor control test of this example.
The odor of (water only) was set to 5, and the odors of other samples were evaluated on a relative scale of 10. (1 ← Small ← 5 → Multiple → 10)
The pH was adjusted with caustic soda and hydrochloric acid.

The results are shown in Table 3. As shown in the results shown in Table 3, it was confirmed that the addition of hydroxylamine sulfate reduced the odor of thinner. As an additive in the comparative example, triethanolamine (TEA) is an example of an alkanolamine known in the literature as a treatment agent for coating booth water, polyethyleneimine having a degree of polymerization of 15000 is an example of a polymeric amine, and a polymer is Examples of flocculants are cationic and have an average molecular weight of 100000 and an average molecular weight.
Compared to polyacrylic cation copolymer over the 5,000,000.

Example 2 This example confirms the antibacterial effect of the present invention. In the experiment, 0.5g / l of hydroxylamine sulfate was added to three kinds of coating booth waters A, B, and C as test liquids producing rotten odor and left for 24 hours. The numbers of bacteria were compared.

The viable cell count was measured by pouring 20 ml of sterile agar medium having the composition shown in Table 4 into a φ90 mm petri dish, and the coating booth water subjected to the above treatment was applied to 300 to 3000 cells per ml. Dilute to 0.1 ml and add 0.1 ml to the prepared agar medium, and spread evenly. CO _{2 on} the petri dish after smearing the bacteria
It is placed in a small container containing a generator, placed in an incubator set at 35 ° C., and cultured for 2 to 3 days. Then, the number of viable bacteria was compared from the number of colonies generated.

The results are shown in Table 5 (results are average values of n = 4). From the results in Table 5, antibacterial properties were confirmed. (Example 3) This example confirms the tack-free effect of the paint mist according to the present invention.

A test solution and 0.5 g / l of urethane-based baking paint were added to a 50 ml sample tube and shaken for 1 minute to give 30, 6
The tack-free property of the paint was confirmed after 0 and 120 minutes. The pH was adjusted with caustic soda and hydrochloric acid.

The test solutions and the results are shown in Table 6. From the results in Table 6, non-stickiness was confirmed. The tack-free property was evaluated on the basis of the amount of adhesion when a filter paper was put in a state where the coating meal was floating on the liquid surface. In the following evaluations, “⊚” and “∘” are passed.

⊚: Almost does not adhere to the filter paper. ◯: Slightly adhered to the filter paper. Δ: A large amount adheres to the filter paper. ×: No change from raw paint

[0043] The contact, as the additive of Comparative Example, the paint booth water treatment agent as triethanolamine Examples of alkanolamines which is used in the literature (TEA), polyethylene having a degree of polymerization of 15000 Examples of polymeric amine Imine,
As an example of the polymer flocculant, a medium cation was compared with a polyacrylic cation copolymer having an average molecular weight of 100,000 and an average molecular weight of 5,000,000.

[0044]

[Table 2]

[0045]

[Table 3]

[0046]

[Table 4]

[0047]

[Table 5]

[0048]

[Table 6]

[0049]

EFFECTS OF THE INVENTION According to the present invention, the odor of thinners accumulated in the circulating water and the spoilage due to the growth of spoilage bacteria are decomposed by an inexpensive and simple means of containing a very small amount of the hydroxylamine compound in the circulating water to the wet coating booth. Generation of odor can be suppressed. As a result, the problem of offensive odor in the work environment and the area around the factory can be improved.

Furthermore, by containing a hydroxylamine compound, circulating water can be provided with further effects such as a non-adhesive effect and a rust preventive effect of the paint mist possessed by this compound, which facilitates the disposal or recycling of the paint residue. At the same time, it is possible to prevent the paint mist from adhering to the circulating water piping system, the circulating pump, and the solid-liquid separation device.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a reaction of a thinner component.

FIG. 2 is a GC measurement chart (* indicates a reaction product).

Continuation of front page (51) Int.Cl. ⁷ Identification code FI C02F 1/50 540 C02F 1/50 540C 560 560Z 1/70 1/70 Z (72) Inventor Hiromi Kojima Nodamachibawari 50, Kariya city, Aichi prefecture Address within Yuken Industry Co., Ltd. (56) Reference JP 5-115708 (JP, A) JP 11-70301 (JP, A) JP 3-42027 (JP, A) JP 5-7878 (JP, A) JP-A-6-200195 (JP, A) JP-A-4-298280 (JP, A) JP-A-51-20234 (JP, A) JP-A-2002-30299 (JP, A) (58) ) Fields surveyed (Int.Cl. ⁷ , DB name) B01D 57/00 C02F 1/50 A01N 33/24

Claims (5)

(57) [Claims] 1. A treatment agent for coating booth water, comprising at least one compound selected from hydroxylamine and salts thereof. Wherein the coating booth water wet paint spray booth, or is characterized by adding at least one compound selected from hydroxylamine and a salt thereof painting booth water from the wet paint booth, paint booth Water treatment method. 3. The remaining Rinomizu separated and recovered paint mist from spray booth water from the wet paint booth circulating water when recycled to the wet spray booth, at least selected from hydroxylamine and its salts A method for treating paint booth water, which comprises adding one compound. 4. An environment in which decay-causing bacteria easily grow
In the wet coating booth, the
Paint mist separated from water in paint booth
・ If the remaining collected water is recycled to the wet coating booth,
A method for suppressing the odor of coating booth water, characterized in that the circulating water of mushrooms contains at least one compound selected from hydroxylamine and salts thereof. 5. The method according to claim 2, wherein the coating mist is at least one coating mist selected from compounds having a carbonyl group.