JP2002030299A - Aqueous alkali detergent for removing scaled coating sludge and method for removing scaled coating sludge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a detergent for removing a scaled coating sludge, having excellent detergency and low flammability, and to provide a method for removing the scaled coating sludge not requiring a manual operation by using the detergent. SOLUTION: This aqueous alkali detergent is used for removing a scaled coating sludge from a solid-liquid separator to which the sludge is stuck and contains an alkali agent, an organic amine, an organic solvent and a surfactant. This method for removing the scaled coating sludge from a centrifugal separator to which the sludge is stuck is characterized in that a detergent is supplied from a detergent tank to the centrifugal separator by a pump to carry out a solid-liquid separation, the sludge is recovered, a liquid is returned to the detergent tank, the coating sludge scaled in the circulation system is removed and the aqueous alkali detergent is used as the detergent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION In the painting process of automobiles and the like, in a wet-type painting booth, paint mist that has not adhered to an object to be coated is collected by water, and a flocculant is added to the mist to form a circulation pit. Sent to The paint sludge dispersion liquid is usually sent from this to a solid-liquid separator such as a centrifugal separator by a pump, where it is separated into paint sludge and a liquid (mainly water). The paint sludge is collected, and the liquid is passed through a circulation pit. By returning, it has been circulated. However, paint sludge is scaled and adhered / accumulated in the solid-liquid separation device during the circulation treatment, which often causes trouble in operation. The present invention relates to an aqueous alkaline cleaner for removing the scaled paint sludge and a method for removing the sludge using the same.

[0002]

2. Description of the Related Art As described above, scaled paint sludge adhering and accumulating in a solid-liquid separation device often causes a problem in operation. For example, paint sludge scaled in a centrifuge generates a rotational load between a screw and a rotary cylinder, causing a trip, and furthermore, after stopping, falls into a state where it cannot be restarted, thus requiring overhaul. For this reason, conventionally, the scaled paint sludge was manually removed by passing the thinner through the inside of the centrifuge, but after removal, the reattachment of the paint sludge was rather increased, resulting in an immediate current overload and operation. There was a problem of becoming abnormal. Furthermore, since the thinner is flammable and involves a risk of fire, it must be handled with great care and the effect on the health of workers has also been a problem.

[0003]

SUMMARY OF THE INVENTION The present invention provides a cleaning agent for removing scaled paint sludge which is excellent in detergency and has no danger of ignition, and a scaled paint sludge removal which does not require manual operation using this cleaner. The aim is to provide a method.

[0004]

As a result of various studies to solve the above-mentioned problems, the present inventors have found a cleaning agent and a scaled paint sludge removing method suitable for this purpose.
The present invention has been completed. The present invention is an aqueous alkaline cleaning agent for removing sludge from a solid-liquid separation device to which scaled paint sludge has adhered, the aqueous alkaline detergent comprising an alkali agent, an organic amine, an organic solvent and a surfactant. A method for removing a sludge from a centrifugal separator to which a cleaning agent and scaled paint sludge are attached, wherein the cleaning agent is supplied to the centrifugal separator by a pump from a cleaning agent tank to perform solid-liquid separation. Recovering the liquid, returning the liquid to a cleaning tank, removing the scaled paint sludge in such a circulation system, and using the aqueous alkaline cleaning agent as the cleaning agent.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION As the alkali agent used in the present invention, a hydroxide, silicic acid or carbonate of an alkali metal or an alkaline earth metal can be used. These can be used alone or in combination of two or more. Specifically, sodium hydroxide, potassium hydroxide,
Examples thereof include calcium hydroxide, sodium silicate, potassium silicate, sodium carbonate, and potassium carbonate, and sodium hydroxide and potassium hydroxide, particularly potassium hydroxide, are preferred.

As the organic amine used in the present invention, mono-, di- or trialkanolamine (here, alkanol is the same or different linear or branched one having 2 to 4 carbon atoms), N- Alkyl or N, N
-Dialkyl-monoalkanolamines (where alkyl is the same or different and is linear or branched having 1 to 4 carbon atoms, and alkanol is linear or branched having 2 to 4 carbon atoms) N-alkyl-dialkanolamines, wherein alkyl is a straight or branched chain having 1 to 4 carbon atoms, and alkanol is the same or a different straight chain having 2 to 4 carbon atoms. Mono-, di- or trialkylamine (where alkyl is the same or different, linear or branched having 1 to 6 carbon atoms), 2 to 2 carbon atoms For example, alkylenediamine having 6 or cycloalkylamine having 5 or 6 carbon atoms can be used. These can be used alone or in combination of two or more. The mono, di or trialkanolamine as monoethanolamine, diethanolamine, triethanolamine,
The above-mentioned N-alkyl or N, N-dialkyl-monoalkanolamine such as monoisopropanolamine, diisopropanolamine and triisopropanolamine; N-methylethanolamine and N, N-dimethylethanolamine; As the amine, N-methyldiethanolamine, N-
Examples of the above mono-, di- or trialkylamine such as ethyldiethanolamine include methylamine, ethylamine, diethylamine and triethylamine; examples of the alkylene diamine include ethylenediamine and propylenediamine; examples of the cycloalkylamine include cyclohexylamine.

The organic solvent used in the present invention is not particularly limited, but may be a lactam solvent, a lactone solvent, an aprotic polar solvent, a saturated aliphatic dicarboxylic acid dialkyl (where alkyl is the same or same). R ¹ O- (alkylene-O) _n -R ² (where R ¹ is the same or different and has 1 to 4 carbon atoms). 8 linear or branched alkyl groups, R ² is a hydrogen atom or the same or different linear or branched alkyl group having 1 to 8 carbon atoms, and alkylene is a linear alkyl group having 2 to 4 carbon atoms. Mono- or polyalkylene glycol mono- or dialkyl ethers or the like. These can be used alone or in combination of two or more.

Lactam solvents such as 5-methylpyrrolidone and N-methylpyrrolidone, lactone solvents such as γ-butyrolactone, δ-valerolactone and γ-valerolactone, and aprotic polar solvents such as dimethyl sulfoxide and sulfolane , Dimethyl sulfone, dimethylformamide, dimethylacetamide, acetonitrile, etc., such as the above-mentioned dialkyl saturated aliphatic dicarboxylate, dimethyl glutarate, dimethyl succinate, dimethyl adipate, etc., and the above mono- or polyalkylene glycol mono- or dialkyl ether diethylene glycol monomethyl ether , Triethylene glycol monomethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, ethylene glycol Monohexyl ether, diethylene glycol monohexyl ether, ethylene glycol mono-2-ethylhexyl ether, diethylene glycol mono-2-ethylhexyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, propylene glycol monopropyl ether, dipropylene glycol Propylene glycol monopropyl ether, propylene glycol monobutyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, dipropylene glycol dimethyl ether, and the like. It can be.

The surfactant used in the present invention is not particularly limited, and any of an anionic surfactant, a cationic surfactant, a nonionic surfactant and a zwitterionic surfactant can be used. Anionic surfactants and nonionic surfactants are preferable, and it is more preferable to use anionic surfactants and nonionic surfactants in combination. The surfactants used in the present invention can be used alone or in combination of two or more.

Specific examples of the anionic surfactant include sodium higher alcohol sulfate, sodium dodecylbenzenesulfonate, sodium alkylnaphthalenesulfonate, sodium polyoxyethylene alkyl ether sulfate, and polyoxyethylene alkylphenyl. Ether sulfate sodium salt,
and sodium salts of β-naphthalenesulfonic acid formaldehyde condensate and sodium salts of dialkyl sulfosuccinates.

As the nonionic surfactant, specifically, polyoxyethylene hexyl ether, polyoxyethylene octyl ether, polyoxyethylene decyl ether, polyoxyethylene lauryl ether, polyoxyethylene palmityl ether, polyoxyethylene Myristyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene tolyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene polyoxypropylene copolymer, Polyoxyethylene polyoxypropylene octyl phenyl ether, polyoxyethylene polyoxypropylene nonyl Phenyl ether, polyoxyethylene polyoxypropylene dodecyl phenyl ether,
Examples thereof include polyoxypropylene octyl phenyl ether, polyoxypropylene nonyl phenyl ether, and polyoxypropylene dodecyl phenyl ether.

The concentration of each component in the aqueous alkaline detergent of the present invention is based on the mass of the aqueous alkaline detergent, from 1 to 30% by mass, particularly from 10 to 20% by mass of the alkaline agent and from 5 to 20% by mass of the organic amine. It is preferred that the amount is 20% by mass, especially 5 to 10% by mass, the organic solvent is 10 to 50% by mass, particularly 10 to 20% by mass, and the surfactant is 1 to 10% by mass, particularly 1 to 5% by mass. The aqueous alkaline cleaning agent of the present invention has a form in which the above components are dissolved or dispersed in water, and is preferably dissolved in water. The amount of water in the aqueous alkaline cleaning agent of the present invention is not particularly limited as long as the above components can be kept in a dissolved or dispersed state.

When using the aqueous alkaline cleaning agent of the present invention, the aqueous alkali cleaning agent is brought into contact with the sludge in a solid-liquid separator to which the scaled coating sludge has adhered, and then rubbed manually or with mechanical force. Remove sludge.

The paint sludge in the paint sludge dispersion in the circulation pit is composed of a paint and a flocculant. Here, paints are usually used for painting automotive bodies and other objects to be coated, home appliances and other industrial products, especially spray painting, polyester resin paint, acrylic alkyd resin paint, melamine alkyd resin paint, epoxy resin It is a paint, a vinyl resin paint, a urethane resin paint, etc., and the aqueous alkaline cleaning agent of the present invention can exert its effects irrespective of the type of these paints. Flocculants are usually
Various coagulants have been actually used or tried in order to simultaneously exert the coagulation effect and the effect of making the paint non-adhesive. For example, a treatment agent containing bentonite clay (U.S. Pat. No. 4,504,395), a treatment agent containing pseudo-boehmite or boehmite type alumina (Japanese Patent Laid-Open No. 18492/1990), and a treatment agent containing sepiolite (Japanese Patent Laid-Open No. 11-77061) ). The aqueous alkaline cleaning agent of the present invention can exert its effects irrespective of the type of these treating agents, but in particular, paint sludge dispersion treated with a treating agent containing pseudo-boehmite type or boehmite type alumina or a treating agent containing sepiolite. Useful for removing liquid-based, scaled paint sludge.

As the solid-liquid separator, a centrifugal separator is usually used, but a belt press (solid-liquid separation by pressing a coating liquid sludge dispersion liquid between belts) and a filter press are also used. In some cases, the aqueous alkaline detergent of the present invention is not only a centrifuge,
It is useful for removing scaled paint sludge adhering and accumulating on other solid-liquid separation devices as described above.

In particular, when removing the sludge from the centrifugal separator to which the scaled paint sludge has adhered using the aqueous alkaline cleaning agent of the present invention, it is preferable to carry out the method described below. As described above, in the painting process of automobiles and the like, in a wet-type painting booth, paint mist that has not adhered to the object is collected by water, and a flocculant is added to the mist and sent to the circulation pit as a paint sludge dispersion. Can be The paint sludge dispersion is usually pumped from here to a centrifuge where the paint sludge and the liquid (mainly water)
And the paint sludge is recovered, and the liquid is returned to the circulation pit for circulation processing. In the method of the present invention, apart from this circulation path, a circulation path is provided from the detergent tank containing the detergent of the present invention to the detergent tank again through the centrifugal separator, thereby removing scaled paint sludge. I do. That is, the cleaning agent is supplied from the cleaning agent tank to the centrifugal separator by a pump to perform solid-liquid separation, and the sludge is collected.
The liquid is returned to the cleaning tank and scaled paint sludge is removed in such a circulation system.

When performing the treatment of the present invention, the circulation path for recovering paint sludge from the paint sludge dispersion is kept closed. The centrifugal separator used in the paint sludge recovery step is a screw decanter type, a separator type (disk type), a cylindrical type (basket type), etc., and the method of the present invention is not limited to any type of centrifuge. The present invention is also applicable to the centrifuge of No. There are no particular restrictions on the operating conditions of the centrifuge for carrying out the method of the present invention, for example, the centrifugal force, the number of revolutions, the difference in revolutions, and the detergent supply speed. The operating time of the centrifuge (detergent circulation time) can be determined by examining the degree of removal of the scaled paint sludge, for example, by comparing the current value of the differential with that before starting the cleaning. The treatment of paint mist is necessary in various fields including the automobile industry, the home appliance industry, and the like, and the cleaning agent and the scaled paint sludge removal method of the present invention can be applied regardless of these industries.

[0018]

EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples. Example detergents and comparative detergents having the following compositions were prepared and subjected to the tests described below.

[0019]

[Table 1]

Test 1 Dissolution rate of scaled paint sludge Dissolved scaled paint sludge collected in a screw decanter type centrifugal separator used for collecting paint sludge from automobile paint mist was collected and used as a cleaning agent in Examples and Comparative Examples. After 1 hour, the residual solid was taken out and dried at 150 ° C., and the weight loss was measured. The dissolution rate was determined according to the following equation. Dissolution rate (% / hr) = ｛(mass before immersion-mass after immersion) x 10
0 / mass before immersion｝ / hr The results are as follows, and the cleaning agents of Examples have excellent cleaning performance as compared with Comparative Example 1 (only potassium hydroxide) and Comparative Example 2 (thinner). Was. Dissolution rate (% / hr) 24 (Example 1), 22 (Example 2), 27 (Example 3), 25 (Example 4) 11 (Comparative example 1), 14 (Comparative example 2),

Test 2 Ability to remove scaled paint sludge accumulated in the centrifuge As shown schematically in FIG. 1, a circulation pit a, a circulation pump b and a screw decanter centrifuge c (manufactured by Tomoe Kogyo Co., Ltd.) P-660SF), a washing tank 1, a washing pump 2, and a centrifugal separator, which share a centrifuge c and a part of piping with a circulation line for collecting paint sludge from a paint sludge dispersion liquid. Machine c,
A circulation line for removing the scaled paint sludge accumulated in the centrifuge c was provided, and a removal test of the scaled paint sludge was performed using the cleaning agent of Example 4 as the cleaning agent to be put in the cleaning agent tank 1. The setting conditions of the centrifugal separator were a centrifugal force of 1200 G, a rotation speed of 3811 rpm, and a rotation difference of 20 rpm.
m, and the detergent supply speed was 8 L / min. Cleaning time is 2
Time. The removal performance of the scaled paint sludge was examined by measuring the differential current value when tap water was circulated for 60 minutes under the operation of the centrifuge before and after washing. As a result, the differential current values were as follows. Initial value 4.8A Before washing 7.0A After washing 5.5A The initial value is an unused state value when the centrifuge is delivered. From the differential current values before and after cleaning, the effect of removing the scaled paint sludge by the method of the present invention is apparent.

[0022]

The cleaning agent for removing scaled paint sludge of the present invention is excellent in detergency and has no danger of ignition. In addition, the method for removing scaled paint sludge of the present invention does not require any manual work and is excellent in removal performance. Furthermore, when the scaled paint sludge is removed by using the cleaning agent or the removing method of the present invention, there is an effect that the scaled paint sludge is less likely to reattach than the conventional method.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a method of a test for removing scaled paint sludge.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) C11D 3/10 C11D 3/10 3/20 3/20 3/26 3/26 3/28 3/28 3 / 30 3/30 3/32 3/32 3/34 3/34 (72) Inventor Toru Sunaga 2-22-1, Nihonbashi-Ningyocho, Chuo-ku, Tokyo F-term in Parker Corporation 4H003 AB18 AB19 AC08 AC11 AC23 BA12 DA11 DB03 EA15 EA16 EA21 EB12 EB14 EB31 ED02 ED29 ED32 FA45 4J038 RA02 RA04 RA08 RA09 RA12

Claims (7)

[Claims] 1. An aqueous alkaline cleaning agent for removing sludge from a solid-liquid separation device to which scaled paint sludge has adhered, comprising an alkaline agent, an organic amine, an organic solvent and a surfactant. Washing soap. 2. The aqueous alkaline detergent according to claim 1, wherein the alkaline agent is a hydroxide, silicic acid or carbonate of an alkali metal or alkaline earth metal. 3. The organic amine is a mono-, di- or trialkanolamine (where the alkanol is the same or a different linear or branched one having 2 to 4 carbon atoms), N-alkyl-mono or dialkanolamine. Alkanolamine (where alkyl means a straight or branched chain having 1 to 4 carbon atoms, and alkanol means a straight or branched chain having the same or different 2 to 4 carbon atoms) Mono-, di- or trialkylamines (where alkyl represents the same or different linear or branched alkyl group having 1 to 6 carbon atoms), alkylenediamine having 2 to 6 carbon atoms or 5 or 6 carbon atoms The aqueous alkaline detergent according to claim 1 or 2, which is a cycloalkylamine. 4. An organic solvent comprising a lactam-based solvent, a lactone-based solvent, an aprotic polar solvent, a dialkyl saturated aliphatic dicarboxylate (where the alkyls are the same or different and are linear or branched having 1 to 4 carbon atoms). Or a general formula R ¹ O- (alkylene-O) _n -R ² , wherein R ¹ is the same or different, and is a linear or branched alkyl group having 1 to 8 carbon atoms; ² is a hydrogen atom or the same or different linear or branched alkyl group having 1 to 8 carbon atoms; alkylene is a linear or branched alkyl group having 2 to 4 carbon atoms; The aqueous alkaline cleaner according to any one of claims 1 to 3, which is a mono- or polyalkylene glycol mono- or dialkyl ether represented by an integer. 5. The method according to claim 1, wherein the surfactant is an anionic surfactant and / or
The aqueous alkaline detergent according to any one of claims 1 to 4, which is a cationic surfactant. 6. An alkaline agent and an organic amine in an amount of 1 to 30% by mass and 5 to 2% by mass, respectively, based on the mass of the aqueous alkaline detergent.
The aqueous alkaline cleaner according to any one of claims 1 to 5, comprising 0% by mass, 10 to 50% by mass of an organic solvent, and 1 to 10% by mass of a surfactant. 7. A method for removing sludge from a centrifugal separator to which scaled paint sludge has adhered, comprising supplying a detergent from a detergent tank to the centrifuge by a pump to perform solid-liquid separation, The sludge is collected, the liquid is returned to the detergent tank, and the scaled paint sludge is removed in such a circulation system, and the aqueous alkaline detergent according to any one of claims 1 to 6 is used as the detergent. A method comprising: