CA2379219A1 - Method for treating circulating water in paint booths - Google Patents
Method for treating circulating water in paint booths Download PDFInfo
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- CA2379219A1 CA2379219A1 CA002379219A CA2379219A CA2379219A1 CA 2379219 A1 CA2379219 A1 CA 2379219A1 CA 002379219 A CA002379219 A CA 002379219A CA 2379219 A CA2379219 A CA 2379219A CA 2379219 A1 CA2379219 A1 CA 2379219A1
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- Prior art keywords
- circulating water
- acid
- dispersants
- alkyl
- paint particles
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
- C02F1/56—Macromolecular compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
- C02F1/547—Tensides
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/68—Treatment of water, waste water, or sewage by addition of specified substances, e.g. trace elements, for ameliorating potable water
- C02F1/683—Treatment of water, waste water, or sewage by addition of specified substances, e.g. trace elements, for ameliorating potable water by addition of complex-forming compounds
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
- C09D7/71—Paint detackifiers or coagulants, e.g. for the treatment of oversprays in paint spraying installations
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/14—Paint wastes
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Materials Engineering (AREA)
- Wood Science & Technology (AREA)
- Paints Or Removers (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
- Emulsifying, Dispersing, Foam-Producing Or Wetting Agents (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
- Separation Of Particles Using Liquids (AREA)
- Details Or Accessories Of Spraying Plant Or Apparatus (AREA)
Abstract
The invention relates to a method for the treatment of circulating water in paint booths, whereby the paint particles are dispersed by adding dispersant s selected from the group consisting of: a) homopolymers and copolymers based on maleic acid, acrylic acid and/or methacrylic acid with a molar mass ranging between 2500 and 500 000; b) non-ionic surface active agents; c) anionic surface active agents, whereby no polyaspartic acid is additionally added to the circulating water in said case and d) inorganic or non-polymeric organic complexing agents and mixtures thereof, their total concentration ranging fr om 0.01 to 2.0 percent by weight in relation to the circulating water. Accordin g to said method for the treatment of circulating water in paint booths, the circulating water has a hardness of at least 2~ measured in accordance with the German water hardness system. By adding dispersants in a concentration ranging between 0.001 and 2.0 percent by weight in relation to the circulati ng water, the paint particles are dispersed in such a way that they have a mean particle size of less than 20 .mu.m determinable by laser diffraction.</SDOA B>
Description
w CA 02379219 2002-O1-14 Henkel KGaA - H 4051 _ 1 _ Dr. Endres / KK
13.07.1999 "Process for the treatment of the circulating water in painting booths"
This invention relates to a process for the treatment of the circulating water in painting booths, particularly for vehicle painting. The paint particles washed out of the waste air and introduced into the circulating water are kept in suspension in finely dispersed form and removed from the circulating water continuously or discontinuously. This is achieved by addition of suitable additives to the circulating water, the concentration of which in the circulating water is set to the relatively low values of between 0.01 and 0.5 wt. % based on the circulating water.
In painting booths in which water-based or solvent-based paints are applied to the surfaces to be painted, the entire quantity of paint used is not applied to the intended surface. Rather, a considerable proportion of the paint particles becomes mixed with the air flowing through the painting booth or settles on the walls of the painting booth. The paint particles, the so-called paint overspray, are washed out of the air stream with water by means of suitable washing devices, such as Venturi scrubbers.
The water mixed with paint is collected in circulating water tanks and circulated. As the paint particles in the circulating water stick together and to equipment parts, however, they are released and coagulated by traditional methods by the addition of release and coagulation agents. The coagulated paint particles settle or float on the circulating water according to the method employed. The thus-produced paint sludge may be removed from the bottom or the surface of the circulating water tank by means of suitable removal devices. This traditional method requires the use of inorganic or organic release and coagulation agents which may be selected, for example, from sheet silicates, waxes and organic polymers. The quantity used of these products is generally from 10 to 50 wt. % based on the paint overspray ready for spraying. The release of the paint particles and removal of the paint sludge is not, however, usually complete so that paint sludge is deposited and has to be removed by hand from time to time, involving a great deal of work. In addition, an additional quantity of sludge is produced where inorganic coagulants are used, and this leads to additional disposal costs.
13.07.1999 "Process for the treatment of the circulating water in painting booths"
This invention relates to a process for the treatment of the circulating water in painting booths, particularly for vehicle painting. The paint particles washed out of the waste air and introduced into the circulating water are kept in suspension in finely dispersed form and removed from the circulating water continuously or discontinuously. This is achieved by addition of suitable additives to the circulating water, the concentration of which in the circulating water is set to the relatively low values of between 0.01 and 0.5 wt. % based on the circulating water.
In painting booths in which water-based or solvent-based paints are applied to the surfaces to be painted, the entire quantity of paint used is not applied to the intended surface. Rather, a considerable proportion of the paint particles becomes mixed with the air flowing through the painting booth or settles on the walls of the painting booth. The paint particles, the so-called paint overspray, are washed out of the air stream with water by means of suitable washing devices, such as Venturi scrubbers.
The water mixed with paint is collected in circulating water tanks and circulated. As the paint particles in the circulating water stick together and to equipment parts, however, they are released and coagulated by traditional methods by the addition of release and coagulation agents. The coagulated paint particles settle or float on the circulating water according to the method employed. The thus-produced paint sludge may be removed from the bottom or the surface of the circulating water tank by means of suitable removal devices. This traditional method requires the use of inorganic or organic release and coagulation agents which may be selected, for example, from sheet silicates, waxes and organic polymers. The quantity used of these products is generally from 10 to 50 wt. % based on the paint overspray ready for spraying. The release of the paint particles and removal of the paint sludge is not, however, usually complete so that paint sludge is deposited and has to be removed by hand from time to time, involving a great deal of work. In addition, an additional quantity of sludge is produced where inorganic coagulants are used, and this leads to additional disposal costs.
There is therefore a need for improved processes for the treatment of the circulating water in painting booths, which may involve a reduced use of chemicals, with which fewer problems caused by sticky paint particles arise and/or in which there is less manual outlay for cleaning and maintaining the painting booths and the disposal costs are distinctly minimized. ' _ In a first embodiment, the present invention provides a process for the treatment of the circulating water in painting booths, wherein the paint particles are dispersed by addition of dispersants which are selected from:
(a) homo- and co-polymers based on malefic acid, acrylic acid and/or methacrylic acid having molecular weights of between 2,500 and 500;000;
(b) non-ionic surfactants;
(c) anionic surfactants, no polyaspartic acid being additionally added to the circulating water in this case;
(d) inorganic or non-polymeric organic complexing agents and mixtures thereof;
the total concentration thereof being between 0.01 and 2.0 wt. % , preferably between 0.02 and 0. 5 wt. % , based on the circulating water.
The success of the process according to the present invention is based on the fact that the paint particles remain dispersed in the circulating water and are not deposited as paint sludge which is difficult to remove. The circulating water may therefore be circulated together with the paint particles dispersed therein without equipment parts becoming sticky.
Homo- and co-polymers based on malefic acid, acrylic acid and/or methacrylic acid are intended to mean those polymers wherein at least part of the monomers consists of the above-mentioned polymerizable carboxylic acids. Other polymerizable monomers may be co-incorporated into the polymers. Polymers which exclusively contain acrylic acid and/or methacrylic acid are used, for example. The molecular weight of the polymers is preferably from 15,000 to 250,000, particularly up to ~ ~ 50,000. The polymers may be added to the circulating water as they are or in salt form. Depending on the pH of the circulating water, the acid/base equilibrium between acid and salt form is automatically adjusted.
In the process according to the present invention, non-ionic surfactants, which are preferably selected from alkoxylates of fatty acids, fatty alcohols or fatty amines having 7 to 36, preferably 10 to 22, carbon atoms in the fatty alkyl group and having 5 to 100, preferably 10 to 80, alkylene oxide units, may be used as dispersants.
These alkoxylates may have the terminal groups thereof closed, i.e. represent so-called mixed ethers.
A butyl group may be present, for example, as a terminal group. Ethylene oxide groups or combinations of ethylene oxide groups and propylene oxide groups are considered in particular as alkylene oxide groups. An alkoxylate of a Clma-fatty alcohol mixture with an average of five ethylene oxide and four propylene oxide units in the molecule may be used for example.
Inorganic or non-polymeric organic complexing agents may further be used as dispersants. These are preferably selected from:
(i) organic carboxylic acids having two to ten heteroatoms, which may coordinate on metal ions, particularly from citric acid, tartaric acid, malic acid, gluconic acid, nitrilotriacetic acid, ethylenediamine tetraacetic acid, methylglycine diacetic acid;
(ii) organic phosphoric acids, particularly from 1-hydroxyethane-1,1-diphosphonic acid, aminotrimethylene phosphoric acid and phosphonobutane tricarboxylic acid;
(iii) oligomeric or polymeric inorganic phosphates, particularly Na triphosphate, Na pyrophosphate and Na hexametaphosphate.
Oxygen atoms (alcohols, carboxylates) or nitrogen atoms are considered in particular as heteroatoms of the organic complexing agents which may coordinate on metal ions.
It is also applicable in each case that the complexing agents may be used in the form of the acids or in salt form. Depending on the pH of the circulating water, a mixture . -~ comprising acid and salt form will be reached according to the acid/base equilibrium.
(a) homo- and co-polymers based on malefic acid, acrylic acid and/or methacrylic acid having molecular weights of between 2,500 and 500;000;
(b) non-ionic surfactants;
(c) anionic surfactants, no polyaspartic acid being additionally added to the circulating water in this case;
(d) inorganic or non-polymeric organic complexing agents and mixtures thereof;
the total concentration thereof being between 0.01 and 2.0 wt. % , preferably between 0.02 and 0. 5 wt. % , based on the circulating water.
The success of the process according to the present invention is based on the fact that the paint particles remain dispersed in the circulating water and are not deposited as paint sludge which is difficult to remove. The circulating water may therefore be circulated together with the paint particles dispersed therein without equipment parts becoming sticky.
Homo- and co-polymers based on malefic acid, acrylic acid and/or methacrylic acid are intended to mean those polymers wherein at least part of the monomers consists of the above-mentioned polymerizable carboxylic acids. Other polymerizable monomers may be co-incorporated into the polymers. Polymers which exclusively contain acrylic acid and/or methacrylic acid are used, for example. The molecular weight of the polymers is preferably from 15,000 to 250,000, particularly up to ~ ~ 50,000. The polymers may be added to the circulating water as they are or in salt form. Depending on the pH of the circulating water, the acid/base equilibrium between acid and salt form is automatically adjusted.
In the process according to the present invention, non-ionic surfactants, which are preferably selected from alkoxylates of fatty acids, fatty alcohols or fatty amines having 7 to 36, preferably 10 to 22, carbon atoms in the fatty alkyl group and having 5 to 100, preferably 10 to 80, alkylene oxide units, may be used as dispersants.
These alkoxylates may have the terminal groups thereof closed, i.e. represent so-called mixed ethers.
A butyl group may be present, for example, as a terminal group. Ethylene oxide groups or combinations of ethylene oxide groups and propylene oxide groups are considered in particular as alkylene oxide groups. An alkoxylate of a Clma-fatty alcohol mixture with an average of five ethylene oxide and four propylene oxide units in the molecule may be used for example.
Inorganic or non-polymeric organic complexing agents may further be used as dispersants. These are preferably selected from:
(i) organic carboxylic acids having two to ten heteroatoms, which may coordinate on metal ions, particularly from citric acid, tartaric acid, malic acid, gluconic acid, nitrilotriacetic acid, ethylenediamine tetraacetic acid, methylglycine diacetic acid;
(ii) organic phosphoric acids, particularly from 1-hydroxyethane-1,1-diphosphonic acid, aminotrimethylene phosphoric acid and phosphonobutane tricarboxylic acid;
(iii) oligomeric or polymeric inorganic phosphates, particularly Na triphosphate, Na pyrophosphate and Na hexametaphosphate.
Oxygen atoms (alcohols, carboxylates) or nitrogen atoms are considered in particular as heteroatoms of the organic complexing agents which may coordinate on metal ions.
It is also applicable in each case that the complexing agents may be used in the form of the acids or in salt form. Depending on the pH of the circulating water, a mixture . -~ comprising acid and salt form will be reached according to the acid/base equilibrium.
The organic complexing agents should not be polymers and should differ in this way from the polymeric carboxylic acids of (a), which also have complexing properties.
The inorganic complexing agents may, however, be entirely polymeric, such as Na pyrophosphate.
Mixtures of representatives of the individual groups of dispersants listed may also be used. Mixtures comprising polyacrylates and phosphoric acids and mixtures comprising niosurfactants and phosphoric acids are particularly suitable.
Where dispersants selected from (a), (b) and (d) are used, 0.2 to 2 wt. % , based on the circulating water, of polyaspartic acid may be additionally added to the circulating water. The use of polyaspartic acid as such is known from patent application PCT/EP99/00350, which is not a prior publication. According to this document, the polyaspartic acid may be used together with anionic surfactants. In the process according to the present invention, however, anionic surfactants may also be used without the co-use of polyaspartic acid. The anionic surfactants to be used as dispersants are preferably selected from soaps, alkyl sulfates, alkyl sulfonates, alkylbenzene sulfonates, alkylether sulfates each having 7 to 44, preferably 8 to 22, carbon atoms in the alkyl group, and from sulfonated malefic acid esters.
In the process according to the present invention, the pH of the circulating water is preferably adjusted to a range between about 5 and about 10.5. A weakly alkaline pH may be preferred. Particularly where phosphoric acids are used as dispersants, particularly advantageous results are obtained when the pH in the circulating water is between about 8 and about 10. At such a pH, dispersants capable of protolysis will be mainly present in salt form, irrespective of the form in which they are introduced into the circulating water. Depending on the form in which the dispersants are used, it may be necessary additionally to use pH adjusters, such as alkali metal hydroxides, to give the preferred pH range.
Depending on the type of paint used, it may further be advisable additionally to add . ~ defoaming agents to the circulating water. The use of defoaming agents is generally known in the technical field in question as foam problems may arise in the circulating water particularly where water-based paints are used.
The process according to the present invention is particularly suitable for painting equipment in which the circulating water exhibits high turbulence. The dispersing effect of the dispersants to be used according to the present invention is increased by the flowing of the circulating water.
When the dispersants according to the present invention are used, the circulating water may be circulated for a certain period of time without the need to remove the entrained paint particles. If the equipment is operated for a fairly long time, however, as time progresses a concentration of paint particles in the circulating water is reached which should not be further exceeded in order to prevent breakdowns. The range in which this concentration limit lies depends on the actual design of the equipment in question. For this reason, the process according to the present invention preferably provides for the removal of a proportion of the paint particles from the circulating water continuously or discontinuously. The preferred procedure in this case is to separate some of the paint particles from the circulating water by means of a membrane filtration, preferably an ultra filtration. The permeate of the membrane filtration is returned to the circulating water and the retentate disposed of.
For this purpose, a portion of the circulating water may be passed over the membrane via a by-pass discontinuously or continuously.
The process according to the present invention functions particularly reliably when it may be ensured, by addition of the dispersants to the circulating water in a concentration between 0.01 and 2.0 wt. % based on the circulating water, that the paint particles in the circulating water have an average particle size, which may be determined by means of laser diffraction, of below about 20 Vim. To achieve this, an addition of suitable dispersants is required for circulating water of a hardness of at least 2 °dH (German hardness) (corresponds to 0.714 mval/1 of alkaline earth metal ions).
The inorganic complexing agents may, however, be entirely polymeric, such as Na pyrophosphate.
Mixtures of representatives of the individual groups of dispersants listed may also be used. Mixtures comprising polyacrylates and phosphoric acids and mixtures comprising niosurfactants and phosphoric acids are particularly suitable.
Where dispersants selected from (a), (b) and (d) are used, 0.2 to 2 wt. % , based on the circulating water, of polyaspartic acid may be additionally added to the circulating water. The use of polyaspartic acid as such is known from patent application PCT/EP99/00350, which is not a prior publication. According to this document, the polyaspartic acid may be used together with anionic surfactants. In the process according to the present invention, however, anionic surfactants may also be used without the co-use of polyaspartic acid. The anionic surfactants to be used as dispersants are preferably selected from soaps, alkyl sulfates, alkyl sulfonates, alkylbenzene sulfonates, alkylether sulfates each having 7 to 44, preferably 8 to 22, carbon atoms in the alkyl group, and from sulfonated malefic acid esters.
In the process according to the present invention, the pH of the circulating water is preferably adjusted to a range between about 5 and about 10.5. A weakly alkaline pH may be preferred. Particularly where phosphoric acids are used as dispersants, particularly advantageous results are obtained when the pH in the circulating water is between about 8 and about 10. At such a pH, dispersants capable of protolysis will be mainly present in salt form, irrespective of the form in which they are introduced into the circulating water. Depending on the form in which the dispersants are used, it may be necessary additionally to use pH adjusters, such as alkali metal hydroxides, to give the preferred pH range.
Depending on the type of paint used, it may further be advisable additionally to add . ~ defoaming agents to the circulating water. The use of defoaming agents is generally known in the technical field in question as foam problems may arise in the circulating water particularly where water-based paints are used.
The process according to the present invention is particularly suitable for painting equipment in which the circulating water exhibits high turbulence. The dispersing effect of the dispersants to be used according to the present invention is increased by the flowing of the circulating water.
When the dispersants according to the present invention are used, the circulating water may be circulated for a certain period of time without the need to remove the entrained paint particles. If the equipment is operated for a fairly long time, however, as time progresses a concentration of paint particles in the circulating water is reached which should not be further exceeded in order to prevent breakdowns. The range in which this concentration limit lies depends on the actual design of the equipment in question. For this reason, the process according to the present invention preferably provides for the removal of a proportion of the paint particles from the circulating water continuously or discontinuously. The preferred procedure in this case is to separate some of the paint particles from the circulating water by means of a membrane filtration, preferably an ultra filtration. The permeate of the membrane filtration is returned to the circulating water and the retentate disposed of.
For this purpose, a portion of the circulating water may be passed over the membrane via a by-pass discontinuously or continuously.
The process according to the present invention functions particularly reliably when it may be ensured, by addition of the dispersants to the circulating water in a concentration between 0.01 and 2.0 wt. % based on the circulating water, that the paint particles in the circulating water have an average particle size, which may be determined by means of laser diffraction, of below about 20 Vim. To achieve this, an addition of suitable dispersants is required for circulating water of a hardness of at least 2 °dH (German hardness) (corresponds to 0.714 mval/1 of alkaline earth metal ions).
Accordingly, in a generalized aspect, the present invention relates to a process for the treatment of the circulating water in painting booths wherein the circulating water has a hardness of at least 2 ° German hardness and wherein the paint particles are dispersed by addition of dispersants in a concentration between 0.01 and 2.0 wt.
based on~the circulating water iwsuch a way that they exhibit an average particle size, which may be determined by means of laser diffraction, of below 20 win.
Laser diffraction is an example of a method of measurement of particle sizes in the micrometer range, in which the light scatter brought about by the particles is measured. A particle size measuring instrument made by Sympatec may be used for this purpose, for example. The average particle size is defined as that particle size which establishes when the particles are kept in suspension by a slight movement of the suspension, for example, by stirring. Ultrasound, which mechanically destroys the particles, is not used in this case.
The above statements apply to the dispersants which may be used under this generalized aspect of the present invention. This also applies to the preferred procedure described above.
In the two embodiments expressed by the independent claims, the present invention is suitable for dispersing water-based and/or solvent-based paints.
Examples Herberts' water-based metallic paint Aqua Pearl Base, Sierra red II was used for the trials. In each case, a quantity of test paint was introduced into water so that the paint solids content was 0.5 wt. % based on the amount of water.
Dusseldn,~/RRnrat~, tap water, which has a hardness of 18 °dH (corresponding to 6.426 mval/1 of alkaline earth metal ions) was used as the water.
In a first set of trials, Sympatec's particle size measuring instrument based on laser diffraction was used to measure the average particle size (defined as 50 %
value) which was established under gentle stirring using the various dispersants. The results are contained in Table 1.
Table 1: Average particle size (50 % value) Example Dispersant/quantity with respect 50 % value to water (~.m) Ref. 1 none ' 255 Example 1 Coconut amine x 12 EO~I~, 0.25 11. 8 %
Example 2 Coconut amine x 12 EO~I~, 0.25 11. 3 %
+ polyaspartic acid, 0.76 ~l~ EO = ethylene oxide In the above set of trials, it was shown that the particle size correlates to the stability of the paint suspension: at a particle size below about 20 ~.m, no sedimentation or flotation may be observed, even 30 minutes after the dispersion was prepared.
Paint does not settle on the glass wall of the test vessel. Further dispersants were therefore only then tested to see whether they exhibit this behavior. Table 2 contains examples.
- g -Table 2: Dispersibility: dispersion stability after 30 minutes Ex. No. Di ersant uanti sp q ty (wt. % based Dispersion Paint on vessel on water) , stable? ~ wall?
Ref. 2 none no (flotation)yes Ref. 3 polyaspartic acid, 0. no (flotation)no 76 %
Ex. 3 modified polyacrylic yes no acid molecular weight 4000, 0.23 Ex. 4 coconut amine x 12 EO yes no Ex. 5 sulfosuccinic acid-bis-2-yes no ethylhexylester, Na salt, 0.38%
Ex. 6 Na oleate, 0.5 % yes no The sediment volume was quantitatively determined in a further set of trials.
For this purpose, the dispersant was placed in a liter of water and stirred for 10 minutes at 300 rpm. The test paint described above was then added in a quantity such that the paint solids content was 0.5 wt. % based on the water. Stirring was repeated for 10 minutes at 300 rpm. The dispersion was then transferred into a measuring funnel (Imhoff cone) and the sediment volume, in ml, measured after a residence time of 10 minutes. Good dispersion is evident from the fact that no sediment appears.
Table 3 contains the results.
Table 3: Sediment volume Ex. No. Dispersant quantity (wt. % based on Sediment water) volume (ml) Ref.4 none 100 Ref. S polyaspartic acid, 0.2 % - 2.5 Ex. 7 polyacrylate (molecular weight 0 10, 000), 0.18 Ex. 8 malefic acid/olefm copolymer (molecular0 weight 12,000), 0.13 Ex. 9 polyacrylate (molecular weight 30,000), 0.2%
Ex. 10 malefic acid/acrylic acid copolymer 0 (molecular weight ' 70,000), 0.2%
Ex. 11 coconut amine x 12 EO, 0.1 %
Ex. 12 Na tripolyphosphate, 0.5 % p Ex. 13 Na pyrophosphate, 0. 5 % 0 Ex. 14 Na hexametaphosphate, 0.5 Ex. 15 citric acid, 0.5 % 0 Ex. 16 1-hydroxyethane-1,1-diphosphonic acid, 0 0.3 %
Ex. 17 aminotrimethylene phosphoric acid, 0.250 % ' Ex. 18 phosphonobutane tricarboxylic acid, 0.25 % 0 Ex. 19 nitrilotriacedc acid, 0.2 % 0 Ex. 20 Cl~"8-fatty alcohol x 25 EO, 0:5 % 0 Ex. 21 Cmla-fatty alcohol x 80 EO, 0.5 % 0 Ex. 22 coconut amine x 15 EO, 0. 5 % 0 Ex. 23 Clma-fatty alcohol sulfate, 0.18% 0 Ex. 24 ring-opened Soya polyol x 10 EO, 0.5 0 %
based on~the circulating water iwsuch a way that they exhibit an average particle size, which may be determined by means of laser diffraction, of below 20 win.
Laser diffraction is an example of a method of measurement of particle sizes in the micrometer range, in which the light scatter brought about by the particles is measured. A particle size measuring instrument made by Sympatec may be used for this purpose, for example. The average particle size is defined as that particle size which establishes when the particles are kept in suspension by a slight movement of the suspension, for example, by stirring. Ultrasound, which mechanically destroys the particles, is not used in this case.
The above statements apply to the dispersants which may be used under this generalized aspect of the present invention. This also applies to the preferred procedure described above.
In the two embodiments expressed by the independent claims, the present invention is suitable for dispersing water-based and/or solvent-based paints.
Examples Herberts' water-based metallic paint Aqua Pearl Base, Sierra red II was used for the trials. In each case, a quantity of test paint was introduced into water so that the paint solids content was 0.5 wt. % based on the amount of water.
Dusseldn,~/RRnrat~, tap water, which has a hardness of 18 °dH (corresponding to 6.426 mval/1 of alkaline earth metal ions) was used as the water.
In a first set of trials, Sympatec's particle size measuring instrument based on laser diffraction was used to measure the average particle size (defined as 50 %
value) which was established under gentle stirring using the various dispersants. The results are contained in Table 1.
Table 1: Average particle size (50 % value) Example Dispersant/quantity with respect 50 % value to water (~.m) Ref. 1 none ' 255 Example 1 Coconut amine x 12 EO~I~, 0.25 11. 8 %
Example 2 Coconut amine x 12 EO~I~, 0.25 11. 3 %
+ polyaspartic acid, 0.76 ~l~ EO = ethylene oxide In the above set of trials, it was shown that the particle size correlates to the stability of the paint suspension: at a particle size below about 20 ~.m, no sedimentation or flotation may be observed, even 30 minutes after the dispersion was prepared.
Paint does not settle on the glass wall of the test vessel. Further dispersants were therefore only then tested to see whether they exhibit this behavior. Table 2 contains examples.
- g -Table 2: Dispersibility: dispersion stability after 30 minutes Ex. No. Di ersant uanti sp q ty (wt. % based Dispersion Paint on vessel on water) , stable? ~ wall?
Ref. 2 none no (flotation)yes Ref. 3 polyaspartic acid, 0. no (flotation)no 76 %
Ex. 3 modified polyacrylic yes no acid molecular weight 4000, 0.23 Ex. 4 coconut amine x 12 EO yes no Ex. 5 sulfosuccinic acid-bis-2-yes no ethylhexylester, Na salt, 0.38%
Ex. 6 Na oleate, 0.5 % yes no The sediment volume was quantitatively determined in a further set of trials.
For this purpose, the dispersant was placed in a liter of water and stirred for 10 minutes at 300 rpm. The test paint described above was then added in a quantity such that the paint solids content was 0.5 wt. % based on the water. Stirring was repeated for 10 minutes at 300 rpm. The dispersion was then transferred into a measuring funnel (Imhoff cone) and the sediment volume, in ml, measured after a residence time of 10 minutes. Good dispersion is evident from the fact that no sediment appears.
Table 3 contains the results.
Table 3: Sediment volume Ex. No. Dispersant quantity (wt. % based on Sediment water) volume (ml) Ref.4 none 100 Ref. S polyaspartic acid, 0.2 % - 2.5 Ex. 7 polyacrylate (molecular weight 0 10, 000), 0.18 Ex. 8 malefic acid/olefm copolymer (molecular0 weight 12,000), 0.13 Ex. 9 polyacrylate (molecular weight 30,000), 0.2%
Ex. 10 malefic acid/acrylic acid copolymer 0 (molecular weight ' 70,000), 0.2%
Ex. 11 coconut amine x 12 EO, 0.1 %
Ex. 12 Na tripolyphosphate, 0.5 % p Ex. 13 Na pyrophosphate, 0. 5 % 0 Ex. 14 Na hexametaphosphate, 0.5 Ex. 15 citric acid, 0.5 % 0 Ex. 16 1-hydroxyethane-1,1-diphosphonic acid, 0 0.3 %
Ex. 17 aminotrimethylene phosphoric acid, 0.250 % ' Ex. 18 phosphonobutane tricarboxylic acid, 0.25 % 0 Ex. 19 nitrilotriacedc acid, 0.2 % 0 Ex. 20 Cl~"8-fatty alcohol x 25 EO, 0:5 % 0 Ex. 21 Cmla-fatty alcohol x 80 EO, 0.5 % 0 Ex. 22 coconut amine x 15 EO, 0. 5 % 0 Ex. 23 Clma-fatty alcohol sulfate, 0.18% 0 Ex. 24 ring-opened Soya polyol x 10 EO, 0.5 0 %
Claims (12)
1. ~A process for treating the circulating water in painting booths, the paint particles being dispersed by addition of dispersants selected from a) nonionic surfactants selected from alkoxylates of fatty acids or fatty amines containing 7 to 36 and preferably 10 to 22 carbon atoms in the fatty alkyl group and 5 to 100 and preferably 10 to 80 alkylene oxide units, b) anionic surfactants, in which case no polyaspartic acid is additionally introduced into the circulating water, in a total concentration of 0.01 to 2.0% by weight, based on circulating water.
2. A process for treating the circulating water in painting booths, the paint particles being dispersed by addition of dispersants selected from a) homo- and copolymers of acrylic acid and/or methacrylic acid with molecular weights in the range from 2,500 to 500,000 and preferably in the range from 15,000 to 250,000, b) nonionic surfactants, c) inorganic or nonpolymeric organic complexing agents, 0.2 to 2% by weight, based on the circulating water, of polyaspartic acid additionally being added to the circulating water.
3. A process as claimed in claim 1, characterized in that the dispersants are anionic surfactants selected from soaps, alkyl sulfates, alkyl sulfonates, alkyl benzenesulfonates, alkyl ether sulfates containing 7 to 44 and preferably 8 to 22 carbon atoms in the alkyl group and from sulfonated maleic acid esters.
4. A process as claimed in one or more of claims 1 to 3, characterized in that the paint particles are removed from the circulating water by membrane filtration.
5. A process for treating the circulating water in painting booths, the circulating water having a hardness of at least 2° German hardness and the paint particles being so dispersed by addition of dispersants in a concentration of 0.01 to 2.0% by weight, based on circulating water, that they have a mean particle size, as determined by laser diffraction, below 20 Nm.
6. A process as claimed in claim 5, characterized in that the dispersants are selected from a) homo- and copolymers based on maleic acid, acrylic acid and/or methacrylic acid with molecular weights in the range from 2,500 to 500,000, \
b) nonionic surfactants, d) inorganic or nonpolymeric organic complexing agents and mixtures thereof.
b) nonionic surfactants, d) inorganic or nonpolymeric organic complexing agents and mixtures thereof.
7. A process as claimed in claim 5, characterized in that the dispersants are nonionic surfactants selected from alkoxylates of fatty acids, fatty alcohols or fatty amines containing 7 to 36 and preferably 10 to 22 carbon atoms in the fatty alkyl group and 5 to 100 and preferably 10 to 80 alkylene oxide units.
8. A process as claimed in claim 5, characterized in that the dispersants are inorganic or nonpolymeric organic complexing agents selected from i) organic carboxylic acids containing two to ten hetero atoms capable of co-ordination to metal ions, more particularly from citric acid, tartaric acid, malic acid, gluconic acid, nitrilotriacetic acid, ethylenediamine tetraacetic acid, methylglycine diacetic acid, ii) organic phosphonic acids, more particularly from 1-hydroxyethane-1, 1-diphosphonic acid, aminotrimethylene phosphonic acid and phosphonobutane tricarboxylic acid, iii) oligomeric or polymeric inorganic phosphates, more particularly Na triphosphate, Na pyrophosphate and Na hexametaphosphate.
9. A process as claimed in one or more of claims 5 to 8, characterized in that dispersants selected from a) homo- and copolymers of acrylic acid and/or methacrylic acid with molecular weights in the range from 2,500 to 500,000 and preferably in the range from 15,000 to 250,000, b) nonionic surfactants, d) inorganic or nonpolymeric organic complexing agents are used and 0.2 to 2% by weight, based on the circulating water, of polyaspartic acid is additionally added to the circulating water.
10. A process as claimed in claim 5, characterized in that the dispersants are selected from c) anionic surfactants and in that no polyaspartic acid is added to the circulating water.
11. A process as claimed in claim 10, characterized in that the anionic surfactants are selected from soaps, alkyl sulfates, alkyl sulfonates, alkyl benzenesulfonates, alkyl ether sulfates containing 7 to 44 and preferably 8 to 22 carbon atoms in the alkyl group and from sulfonated maleic acid esters.
12. A process as claimed in one or more of claims 5 to 11, characterized in that the paint particles are removed from the circulating water by membrane filtration.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19932766A DE19932766A1 (en) | 1999-07-14 | 1999-07-14 | Process for treating the circulating water in paint booths |
| DE19932766.1 | 1999-07-14 | ||
| PCT/EP2000/006291 WO2001005896A1 (en) | 1999-07-14 | 2000-07-05 | Method for treating circulating water in paint booths |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2379219A1 true CA2379219A1 (en) | 2001-01-25 |
Family
ID=7914653
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002379219A Abandoned CA2379219A1 (en) | 1999-07-14 | 2000-07-05 | Method for treating circulating water in paint booths |
Country Status (13)
| Country | Link |
|---|---|
| EP (1) | EP1196504B1 (en) |
| JP (1) | JP2003505222A (en) |
| KR (1) | KR20020025955A (en) |
| AR (1) | AR024740A1 (en) |
| AT (1) | ATE294844T1 (en) |
| AU (1) | AU6268500A (en) |
| BR (1) | BR0012372A (en) |
| CA (1) | CA2379219A1 (en) |
| DE (2) | DE19932766A1 (en) |
| ES (1) | ES2240127T3 (en) |
| MX (1) | MXPA02000447A (en) |
| PL (1) | PL353168A1 (en) |
| WO (1) | WO2001005896A1 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9333521B2 (en) | 2011-07-27 | 2016-05-10 | Dürr Systems GmbH | Filter installation and method for operating a filter installation |
| US9364845B2 (en) | 2011-07-27 | 2016-06-14 | Dürr Systems GmbH | Painting installation and method for operating a painting installation |
| US9381465B2 (en) | 2011-11-02 | 2016-07-05 | Dürr Systems GmbH | Method for the thermal conditioning of an auxiliary material and conditioning facility |
| US9382139B2 (en) | 2011-04-14 | 2016-07-05 | Basf Se | Method of dissolving and/or inhibiting the deposition of scale on a surface of a system |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10155759A1 (en) | 2001-11-14 | 2003-05-22 | Henkel Gmbh | Device and method for cleaning the gratings of a painting booth |
| US8328868B2 (en) | 2004-11-05 | 2012-12-11 | Sadra Medical, Inc. | Medical devices and delivery systems for delivering medical devices |
| DE102011052298A1 (en) * | 2011-07-29 | 2013-01-31 | Dürr Systems GmbH | Filter system for use in paint shop for coating workpieces such as vehicle body, has processing device that is provided for processing paint overspray and filter aid material |
| DE102014215380B4 (en) | 2014-08-05 | 2022-04-28 | Evonik Operations Gmbh | Nitrogen-containing compounds suitable for use in the manufacture of polyurethanes |
| EP3305731A1 (en) * | 2016-10-08 | 2018-04-11 | Oliver Roeber | Process for water treatment |
| CN108581183B (en) * | 2018-06-06 | 2024-06-25 | 浙江工贸职业技术学院 | Laser surface treatment equipment before workpiece spraying |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1513413A (en) * | 1966-12-13 | 1968-02-16 | Parker Ste Continentale | Improved process for denaturing paints and composition for its implementation |
| FR2223438A1 (en) * | 1973-03-28 | 1974-10-25 | Air Ind | PAINT DENATURATION COMPOSITIONS, ESPECIALLY FOR THE CLEANING OF PAINT CABINS |
| CH680710A5 (en) * | 1989-12-22 | 1992-10-30 | Unicolor Ag | |
| JPH0640991B2 (en) * | 1990-02-16 | 1994-06-01 | 栗田工業株式会社 | Wet coating booth treatment agent |
| US5200104A (en) * | 1991-11-08 | 1993-04-06 | Nortru, Inc. | Composition for the treatment of overspray in paint spray booths |
| EP0590897A3 (en) * | 1992-09-30 | 1995-09-27 | Calgon Corp | Improved method for treating oversprayed solvent-based paints |
| JP2880622B2 (en) * | 1993-05-14 | 1999-04-12 | 日本ペイント株式会社 | How to reuse the separated liquid of recovered paint |
-
1999
- 1999-07-14 DE DE19932766A patent/DE19932766A1/en not_active Withdrawn
-
2000
- 2000-07-05 CA CA002379219A patent/CA2379219A1/en not_active Abandoned
- 2000-07-05 AT AT00949257T patent/ATE294844T1/en not_active IP Right Cessation
- 2000-07-05 KR KR1020027000449A patent/KR20020025955A/en not_active Application Discontinuation
- 2000-07-05 MX MXPA02000447A patent/MXPA02000447A/en not_active Application Discontinuation
- 2000-07-05 BR BR0012372-2A patent/BR0012372A/en not_active Application Discontinuation
- 2000-07-05 PL PL00353168A patent/PL353168A1/en not_active Application Discontinuation
- 2000-07-05 JP JP2001511117A patent/JP2003505222A/en active Pending
- 2000-07-05 AU AU62685/00A patent/AU6268500A/en not_active Abandoned
- 2000-07-05 DE DE50010239T patent/DE50010239D1/en not_active Expired - Fee Related
- 2000-07-05 WO PCT/EP2000/006291 patent/WO2001005896A1/en active IP Right Grant
- 2000-07-05 ES ES00949257T patent/ES2240127T3/en not_active Expired - Lifetime
- 2000-07-05 EP EP00949257A patent/EP1196504B1/en not_active Expired - Lifetime
- 2000-07-14 AR ARP000103618A patent/AR024740A1/en unknown
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9382139B2 (en) | 2011-04-14 | 2016-07-05 | Basf Se | Method of dissolving and/or inhibiting the deposition of scale on a surface of a system |
| US9333521B2 (en) | 2011-07-27 | 2016-05-10 | Dürr Systems GmbH | Filter installation and method for operating a filter installation |
| US9364845B2 (en) | 2011-07-27 | 2016-06-14 | Dürr Systems GmbH | Painting installation and method for operating a painting installation |
| US9381465B2 (en) | 2011-11-02 | 2016-07-05 | Dürr Systems GmbH | Method for the thermal conditioning of an auxiliary material and conditioning facility |
Also Published As
| Publication number | Publication date |
|---|---|
| ES2240127T3 (en) | 2005-10-16 |
| DE19932766A1 (en) | 2001-01-18 |
| KR20020025955A (en) | 2002-04-04 |
| WO2001005896A1 (en) | 2001-01-25 |
| MXPA02000447A (en) | 2002-07-02 |
| BR0012372A (en) | 2002-03-26 |
| ATE294844T1 (en) | 2005-05-15 |
| JP2003505222A (en) | 2003-02-12 |
| EP1196504B1 (en) | 2005-05-04 |
| DE50010239D1 (en) | 2005-06-09 |
| EP1196504A1 (en) | 2002-04-17 |
| AR024740A1 (en) | 2002-10-23 |
| PL353168A1 (en) | 2003-11-03 |
| AU6268500A (en) | 2001-02-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |