JPH11672A - Wet coating booth treating agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen the addition amount of a chemical agent, improve the print resistance effect, and prevent facility corrosion by adding sepiolite to a wet coating booth treating agent. SOLUTION: Sepiolite which is a naturally produced clay mineral or sepiolite produced by purifying the natural sepiolite and sold in markets is added to a wet coating booth treating agent. From a viewpoint of the print resistance effect, the size of the particle of the sepiolite is controlled to have about 50 μm or shorter fiber length and preferably about 10 μm or shorter. Moreover, a cationic polymer with about 1000 molecular weight may be used together with the sepiolite. As the cationic polymer, dimethyldiallylammonium chloride may be used. Such a wet coating booth treating agent is employed for a chemical agent addition part 6 and spray coating is carried out by a spray gun 5, so that no facility corrosion problem is caused and high print resistance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet coating booth treating agent, and more particularly to a wet coating booth which reduces the stickiness of paint in circulating water sprayed to collect oversprayed paint, The present invention relates to a wet coating booth treating agent that prevents the solidification of paint in a system.

[0002]

2. Description of the Related Art In a painting process in the automobile industry, the yield of paint sprayed on a vehicle body is generally 60 to 60%.
80%, and 40-20% of the paint used is excess paint to be removed in the next step. This excess sprayed excess paint is usually collected in a wet coating booth by washing, and the washing water is circulated.

In such a wet coating booth, the excess paint collected in the washing water has high adhesiveness, and thus adheres to a water curtain plate, a piping system, a spray nozzle, etc. of the spray booth and clogs the piping and the nozzle. And the washing efficiency is remarkably reduced. In addition, when the exhaust system of the spray booth is clogged due to the adhesion of excess paint and the flow of air is hindered, the booth is filled with a paint solvent, which is a dangerous state for safety and health, which significantly deteriorates the working environment. . Moreover,
Most of the surplus paint is at the bottom of the booth pit of the spray booth,
The paint that has settled at the bottom of the circulation pit and solidified as time elapses becomes a rubber-like material, requiring a great deal of labor and labor for cleaning and removing.

[0004] In order to solve such problems, the following are conventionally used as coating booth treating agents to be mixed in the washing water.

Alkaline agents such as NaOH and KOH Amphoteric metal salts such as Zn salts Cationic polymers and metal salts Bentonite (montmorillonite, hectorite) In the treatment of wastewater containing oily substances, a method of solid-liquid separation after adding sepiolite However, it does not mention adaptation to wet coating booth processing which requires tack-free substances and requires a large amount of solids.

[0006]

Of the above-mentioned conventional wet coating booth treating agents, alkaline agents do not have a sufficient tackifying effect, and amphoteric metal salts and cationic polymers require a large amount of addition. There is a risk of material corrosion due to an increase in the salt concentration of In addition, bentonite also has a disadvantage that a large amount of a cationic polymer must be used in combination because the effect of detackification is not sufficient.

The present invention solves the above-mentioned conventional problems, and provides a wet coating booth treating agent which has a high tack-free effect, can reduce the amount of chemicals added, and does not cause a problem of equipment corrosion. Aim.

[0008]

The wet coating booth treating agent of the present invention contains sepiolite.

The wet coating booth treating agent of the present invention may contain a cationic polymer and / or an amphoteric metal compound together with sepiolite.

Although the details of the effect of tackifying by the wet coating booth treating agent of the present invention are not clear, it is presumed as follows.

The sepiolite is Mg ₈ Si ₁₂ O ₃₀ (OH)
₄ (OH ₂₎ with ₄ · 8H ₂ O in hydrous magnesium silicate represented, because it is fibrous mineral having a chain structure having a number of micropores, paint particles within the micropores react with the paint particles To make the paint tack-free by adsorbing it.

Since the paint particles and the sepiolite particles are both electrically negatively charged, when a cationic polymer or an amphoteric metal compound is used in combination, the electric repulsion is reduced, and the paint particles are easily adsorbed on the sepiolite. As a result, the tackifying effect is improved.

[0013]

Embodiments of the present invention will be described below in detail.

In the present invention, sepiolite includes
Sepiolite, a naturally occurring clay mineral, or a commercially available product obtained by purifying it, can be used. From the viewpoint of the tackifying effect, the particle size is 50 μm as a fiber length.
The thickness is more preferably 10 μm or less.

The cationic polymer used in combination with sepiolite is a cationic polymer having a molecular weight of 1,000 or more, preferably several thousand to several hundred thousand, specifically,
Dimethyldiallylammonium chloride, condensate of alkylamine and epichlorohydrin, ethyleneimine,
Condensate of alkylene dichloride and polyalkylene polyamine, condensate of dicyandiamide and formalin, DA
M (a homopolymer or copolymer of dimethylaminoethyl methacrylate) or the like can be used.

As the amphoteric metal compound, PAC
(Polyaluminum chloride), sulfate band (aluminum sulfate), aluminum compounds such as polyaluminum hydroxychloride, pseudoboehmite alumina sol (AlO (OH)), iron compounds such as ferric chloride, zinc compounds such as zinc chloride, etc. be able to.

The type of the wet coating booth to which the wet coating booth treating agent of the present invention is applied is not particularly limited, and may be a dispersion type or a floating type. In any case, sepiolite or a cationic polymer or an amphoteric metal compound is previously added to circulating water so as to have a predetermined concentration. The treating agent adheres to the surplus paint, becomes tack-free, and is discharged out of the system together with the paint sludge in the sludge separation step. Therefore, an appropriate amount is replenished.

The greater the amount of sepiolite added, the finer the paint particles and the higher the tack-free effect. Sepiolite varies depending on the type of paint to be treated and the like, but generally has a concentration in circulating water of 1 ppm or more, particularly
It is preferable to add so that it becomes 0 ppm or more, especially 500 ppm or more.

The more effective amount of sepiolite added depends on the type of wet coating booth as follows.

(1) In the case of the dispersion type In the case of the dispersion type in which the circulating water system is a uniform suspension system of the paint sludge and a part thereof is collected by a separation device such as a centrifugal dehydrator to recover SS, a sufficient anti-adhesion effect is obtained. Since it is necessary to obtain the effect of dispersing particles, it is often difficult to apply the agent in a wet coating booth. However, in the agent for wet coating booth of the present invention, sepiolite is 50 ppm or more, especially 100 ppm, in circulating water.
By adding a relatively high concentration of about 500 ppm, a sufficient tackifying effect and dispersing effect can be obtained. In this case, the sepiolite will be attached to the excess paint and will be consumed, and will be discharged along with the SS recovered by the separation device.
Depending on the paint and the paint booth, the sepiolite is continuously or batch-injected at a rate of 0.1% by weight or more, especially 1 to 5% by weight, based on the solid weight of the surplus paint brought into the circulating water. preferable.

In particular, when the wet coating booth treating agent of the present invention is applied to the dispersion type wet coating booth, the sludge recovery efficiency is good and the water content of the recovered sludge can be sufficiently reduced.

(2) In the case of the floating type In the case of the floating type, there is no problem even if it is slightly sticky as compared with the case of the dispersion type.
The effect can be obtained with a relatively low concentration of m or more, particularly 50 to 200 ppm.

In this case, the solid content of the surplus paint brought into the circulating water is 0.1% by weight or more, especially 0.5% by weight.
It is preferred to replenish 〜2% by weight of sepiolite by continuous or batch injection.

When a cationic polymer is used in combination with sepiolite, the amount thereof is 0.01 to 20% by weight, preferably 0.5 to 20% by weight, based on the amount of the active ingredient based on sepiolite.
10% by weight, and the colloid equivalent value relative to the circulating water is 0.001 to 1 meq / L, particularly 0.002 to 0.5 m
It is preferable to add eq / L.

If the amount of the cationic polymer is less than the above range, a good combined effect cannot be obtained, and if the amount is too large, the effect of making the coating non-adhesive becomes poor.

When an amphoteric metal compound is used in combination with sepiolite, the amount of the amphoteric metal compound is preferably 0.01 to 10% by weight, particularly 1 to 10% by weight in terms of metal oxide based on sepiolite.

If the added amount of the amphoteric metal compound is less than the above range, a good combined effect cannot be obtained, and if it is too large, the concentration of salts in the circulating water increases, causing a problem of equipment corrosion.

The method of adding sepiolite is not particularly limited, and it may be added as a powder or as a water suspension of about 0.1 to 10% by weight.

When a cationic polymer is used in combination with sepiolite, the cationic polymer may be added separately from sepiolite or may be added by mixing in advance. If added before mixing, mix sepiolite in water,
After 1 minute or more, preferably 20 to 30 minutes after mixing, the sepiolite is sufficiently dispersed and thickened, and then it is preferable to add a cationic polymer to prepare a mixed solution. In the case of a mixed solution in which sepiolite is added after adding a cationic polymer to water, the tackifying effect is generally low.

When an amphoteric metal compound is used in combination, it is preferable to add the amphoteric metal compound separately from sepiolite. When the amphoteric metal compound and sepiolite are mixed in water in advance, the tackifying effect is low.

It is also possible to use a cationic polymer and an amphoteric metal compound together with sepiolite.

In the present invention, in addition to sepiolite, cationic polymer and amphoteric metal compound, various anionic and nonionic polymer polymers such as polyacrylamide and its partial hydrolyzate, acrylic acid or methacrylic acid-based polymer And the like may be added in combination, whereby the aggregation and solid-liquid separation of the paint sludge can be promoted.

Further, an alkali agent such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and the like may be added in combination, thereby neutralizing the inside of the system and preventing the equipment from being corroded.

[0034]

The present invention will be described in more detail with reference to the following examples and comparative examples. However, the present invention is not limited to the following examples unless it exceeds the gist of the present invention.

Examples 1 to 7, Comparative Examples 1 to 6 The effects of various drugs were tested using the test apparatus shown in FIG.

In FIG. 1, 1 is a pit, 2 is a water curtain,
3 is a circulating water pipe provided with a circulating water pump P, 4 is an exhaust pipe provided with an exhaust fan 4A, and W is a water surface. 5 is pit 1
Is a spray gun provided above the water curtain plate 2 for spraying paint. Reference numeral 6 denotes a drug addition section.

The test was carried out with a circulating water flow rate of 100 liters / minute using a test apparatus shown in the figure having a washing water volume of 50 liters. As the washing water, each of the chemicals shown in Table 1 was added so as to have the added amount shown in Table 1, and after spraying the middle paint for automobile factory from the spray gun 5 at a speed of 15 g / min for 2 minutes. The adhesiveness of the paint was evaluated based on the following criteria based on the feeling when touched with a finger. The results are shown in Table 1.

Evaluation Criteria : Same as raw paint. Stick to finger. Δ: Slightly less sticky than raw paint and hardly adhered. ：: Almost no tackiness and no adhesion.

[0039]

[Table 1]

[0040]

As described in detail above, according to the wet coating booth treating agent of the present invention, a good anti-adhesion effect can be obtained without causing problems such as equipment corrosion and the like. Nozzle clogging or the like due to adhesion is prevented, the rinsing effect is favorably maintained, and maintenance is reduced. Deterioration of the working environment due to blockage of the exhaust system or the like is prevented. The paint sludge deposited or floated on the booth pit or the like is hardly solidified and can be easily removed. Therefore, the removal operation is reduced. The washing waste liquid is easily separated into solid and liquid, and the wastewater treatment is facilitated. Sludge with a low water content can be separated and removed with a high separation efficiency, the clarity of the circulating water washing water can be maintained at a high level, and the treatment of the sludge becomes easy. Thus, the coating booth can be industrially extremely advantageously performed.

In particular, by using a cationic polymer or an amphoteric metal compound together with sepiolite, the tack-free effect can be drastically improved. In this case, however, the addition amount of the cationic polymer or the amphoteric metal compound is extremely small. Since a small amount is sufficient, the rise in salt concentration in the circulating water is small, and no equipment corrosion occurs.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a test apparatus used in an example.

[Explanation of symbols]

 1 pit 2 water curtain 5 spray gun

Claims (3)

[Claims] 1. A wet coating booth treating agent comprising sepiolite. 2. A wet coating booth treating agent comprising sepiolite and a cationic polymer. 3. A wet coating booth treating agent comprising sepiolite and an amphoteric metal compound.