CA2252044A1 - Use of aspartic acid-containing polymers in cooling circuits with added biocides - Google Patents
Use of aspartic acid-containing polymers in cooling circuits with added biocides Download PDFInfo
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- CA2252044A1 CA2252044A1 CA002252044A CA2252044A CA2252044A1 CA 2252044 A1 CA2252044 A1 CA 2252044A1 CA 002252044 A CA002252044 A CA 002252044A CA 2252044 A CA2252044 A CA 2252044A CA 2252044 A1 CA2252044 A1 CA 2252044A1
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
- C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
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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
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
- C02F5/08—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents
- C02F5/10—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents using organic substances
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F251/00—Macromolecular compounds obtained by polymerising monomers on to polysaccharides or derivatives thereof
Abstract
The use of bio-degradable organic polymers with a mean molar mass of over 500 in hydraulic cooling systems, in which the aqueous phase of the cooling system additionally contains 0.05 to 5 mg/l of an oxidant with a more positive standard redox potential than oxygen.
Description
CA 022~2044 1998-10-09 The Use of Polymers Containing Aspartic Acid in Biocide-containing Cooling Circuits The present invention relates generally to the conditioning of cooling waters for water-based cooling systems. Conditioning in the context of the invention means above all reducing the corrosive effect of the water phase and stabilizing it against the formation of deposits, the deposition of hardnesssalts and the formation of biological coatings. The invention is suitable both for open and for closed cooling systems and relates equally to throughflow cooling systems and to circulation-type cooling systems. It is designed in particular for open circulation cooling systems. Since the cooling effect of open circulation cooling systems is based on the evaporation of water, the resulting concentration of water ingredients and the free access of air makes them particularly susceptible to the formation of inorganic and organic coatings or deposits.
Key components in the conditioning of cooling water include hardness stabilizers, dispersants, corrosion inhibitors and biocides. Examples of hardness stabilizers are inorganic polyphosphates, phosphonic acids, aminomethylene phosphonic acids, phosphoric acid esters, phosphono-carboxylic acids and polycarboxylic acids, for example of the partly saponified polyacrylamide type or the acrylic acid and/or methacrylic acid polymer or copolymer type. The polycarboxylic acids mentioned can also act as dispersants, in other words they stabilize microdispersed solid particles against ~edimentation and sludge formation. Apart from the partly hydrolyzed polyacrylamides and the acrylic acid and/or methacrylic acid polymers or copolymers mentioned, other suitable dispersants include polystyrene sulfonates, polyvinyl sulfonates, quaternary ammonium compounds, unsaponified polyacrylamides and polyalkylene glycols. Besides substances CA 022~2044 1998-10-09 which have a toxic effect on microorganisms, the microbicides used also include substances whose microbicidal effect is based on their oxidation potential. Oxidative microbicides have the disadvantage that they lose their effectiveness when they have oxidized other substances and have thus been exhausted. However, this disadvantage, which can be offset by continuous or periodic replenishment, is an advantage when the cooling water is completely or partly drained from the cooling system. Since oxidative microbicides are rapidly exhausted, they have generally become inactive by the time the cooling containing them enters the environment. Examples of oxidative microbicides are ozone, chlorine, bromine, chlorine dioxide, hypochlorites, hypobromites or hydrogen peroxide.
The organophosphorus compounds or organic polymers used as hardness stabilizers and/or as dispersants generally have the disadvantage that they are not biologically degradable. This lack of degradability is an advantage as long as these conditioning agents remain in the cooling circuit.
However, it becomes a disadvantage when the cooling medium is completely or partly drained off and enters the environment with or without any waste-water treatment. Accordingly, there is a need for hardness stabilizers and/or dispersants which show adequate biological degradability so that they can be rapidly biologically degraded at the latest when the cooling water to which they are added is drained from the cooling system.
Biologically degradable polymers suitable for use in the conditioning of water have recently been described. For example, WO 94/01476 relates to graft copolymers of unsaturated monomers and sugars, to processes for their production and to their use. The polymers described in this document consist of graft copolymers of monosaccharides, disaccharides and oligosaccharides, reaction products and derivatives thereof and a monomer mixture obtainable by radical graft copolymerization of a monomer mixture of 1 ) 45 to 96% by weight of at least one monoethylenically unsaturated C3 10 CA 022~2044 1998-10-09 monocarboxylic acid, 2) 4 to 55% by weight of at least one monoethylenically unsaturated monomer containing sulfonic acid groups, a monoethylenically unsaturated sulfuric acid ester and/or vinyl phosphonic acid, 3) 0 to 30% by weight of at least one water-soluble monoethylenically unsaturated compound modified with 2 to 50 moles of alkylene oxide per mole, 4) 0 to 45% by weight of at least one other water-soluble, radical-polymerizable monomer, 5) 0 to 30% by weight of other water-insoluble or substantially water-insoluble radical-polymerizable monomers, the sum of 1 ) to 5) being 100% by weight and the acids being replaceable by their salts with monovalent cations, in the presence of mono-, di- and oligosaccharides, reaction products and derivatives thereof or mixtures thereof, the content of the saccharide components in the mixture as a whole being from 5 to 60% by weight.
DE-A 43 00 772 also describes biologically degradable copolymers, a process for their production and their use. These biologically degradable copolymers are polymers of 1) 10 to 70% by weight of monoethylenically unsaturated C48 dicarboxylic acids, 2) 20 to 85% by weight of monoethy-lenically unsaturated C3 ,0 monocarboxylic acids, 3) 1 to 50% by weight of monounsaturated monomers which, after hydrolysis or saponification, can be converted into monomer units with one or more hydroxyl groups covalently bonded to the C-C chain and 4) 0 to 10% by weight of other radical-copoly-merizable monomers, the sum of 1 ) to 4) being 100% by weight and the acids being replaceable by their salts with monovalent cations.
Biologically degradable polymers suitable for use in the conditioning of water can also be found among naturally occurring polymers and derivatives thereof selected from polysaccharides, polyglycosides, poly-glucosides, oxidized cellulose, oxidized starch, oxidized dextrin, proteins.
In addition, polyaspartic acids and polymers containing aspartic acid have been proposed as biologically degradable polymers which may be used as dispersants or as scale inhibitors in the treatment of water. For example, CA 022~2044 1998-10-09 WO 94/19409 describes the production and use as dispersants of water-soluble salts of beta-polyaspartic acid, i.e. a polyaspartic acid in which most of the monomers are linked by beta-bonds. The average molecular weight is in the range from about 1,000 to about 5,000. In addition, it is apparent from WO 92/16462 that a polyaspartic acid obtained by hydrolysis of anhydro-aspartic acid is eminently suitable for preventing calcium carbonate and calcium phosphate scale. Other particulars of the synthesis of alpha- and beta-polyaspartic acid can be found in US-A-5,057,597. According to this document, the particulate monomeric amino acid is heated in a fluidized bed to a temperature of at least 180~C and is kept at a temperature of 180 to 250~C until the required degree of polymerization to anhydroaspartic acid is achieved with elimination of water. The anhydropolyaspartic acid is then hydrolyzed, preferably under alkaline conditions. An alternative method of production is described in WO 93/23452, according to which maleic acid is reacted with excess ammonia at temperatures of 200 to 300~C to form polyaspartic acid. The acid can be converted into its salts by reaction with a base.
WO 94/01486 describes modified polyaspartic acids, which may be used for example as water treatment agents, and processes for their production. These modified polyaspartic acids are obtained by polycon-densation of 1 to 99.9 mole-% of aspartic acid with 99 to 0.1 mole-% of fatty acids, polybasic carboxylic acids, monobasic polyhydroxycarboxylic acids, alcohols, amines, alkoxylated alcohols and amines, amino sugars, carbo-hydrates, sugar carboxylic acids and/or non-proteinogenic aminocarboxylic acids. The modified polyaspartic acids may also be prepared by radical-initiated graft copolymerization of monoethylenically unsaturated monomers in the presence of polyaspartic acids. In addition, WO 94/20563 describes a process for the production of reaction products of polyaspartic acid imides and amino acids and reaction products of polyaspartic acid imides with CA 022~2044 1998-10-09 alkanolamines or aminated fatty alcohol ethoxylates. Reaction products such as these are also suitable as scale inhibitors and as dispersants.
Other polymers and copolymers of aspartic acid, optionally in conjunction with other amino acids, are described for example in WO
92/17194, WO 94/03527, WO 94/21710 and DE-A-43 08 426. WO 94/19288 describes the use of polyaspartic acid and a large number of other products for preventing deposits in a building drainage system, for example in tunnels, galleries, concrete dams, dikes and the like. According to the teaching of EP-A-672 625, improved formulations for treating water are obtained by using polyaspartic acid or a derivative thereof in conjunction with a phosphonic acid.The ratio by weight of polyaspartic acid or derivative to phosphonic acid is preferably in the range from 90:10 to 10:90. The preferred polyaspartic acid is beta-polyaspartic acid with a molecular weight of 1,000 to 10,000.
Although the use of biologically degradable polymers, such as for example polyaspartic acid or other polymers containing polyaspartic acid, for the treatment of water is generally known from the literature cited above, the use of these biodegradable polymers at least in open cooling systems is problematical. The polymers can be expected to undergo rapid degradation in the cooling circuit itself, so that their effect is soon lost and their use is uneconomical. The problem addressed by the present invention was to stabilize these polymers against biological degradation in the cooling system without in any way impeding their degradation after leaving the cooling system. The prior-art literature does not contain any reference to the fact thatproducts of the type in question can be used together with biocidal oxidizing agents in cooling circuits. A potential application such as this appears doubfful because the oxidizing agents can be expected to react with and deactivate the polymers. By contrast, the present invention addressed the further problem of providing a combination of biodegradable polymers and biocidal oxidizing agents which could be used for conditioning water in cooling CA 022~2044 1998-10-09 circuits and which would remain active for a suffficiently long period under in-use conditions.
The problems stated above have been solved by the use of biologically degradable organic polymers with an average molecular weight above 500 in water-based cooling systems, characterized in that the water phase of the cooling systems additionally contains 0.05 to 5 mg/l of an oxidizing agent with a more positive standard redox potential than oxygen.
Standard redox potentials, also known as normal potentials, are generally known thermodynamic terms which are described in manuals of general or physical chemistry, cf. for example Chapter 11 of the manual: H.R.
Christen "Grundlagen der allgemeinen und anorganischen Chemie", Verlag Sauerlader-Salle, 1973. On pages 692 to 697, this manual contains a list of different normal potentials which can also be found in many other manuals and tabular works. The value of the standard redox potential is normally expressed in volts.
Oxidizing agents which a standard redox potential of > 0.4 volt are preferably used for the purposes of the present invention. This oxidizing agent is preferably selected from hydrogen peroxide, chlorine, bromine, chlorine dioxide, hypochlorites, hypobromites and ozone. Since these chemicals are capable of entering into acid-base and/or disproportionation reactions with water, the oxidizing agents mentioned above also include their reaction products with water.
Biological degradability can be measured by various methods. For example, it can be evaluated by the modified STURM Test (OECD Guideline No. 301 B) in which the quantity of carbon dioxide formed during degradation is measured. Alternatively, a modified MITI Test (OECD Guideline 301 for testing chemicals), in which the amount of oxygen consumed during degradation is measured, can be used. In the context of the present invention, polymers are regarded as biologically degradable if more than 50%
CA 022~2044 1998-10-09 degradation is observed after a test period of 28 days.
The biologically degradable polymers suitable for the purposes of the invention may be selected, for example, from a) graft copolymers of monosaccharides, disaccharides and oligosaccha-rides, reaction products and derivatives thereof and a monomer mixture obtainable by radical graft copolymerization of a monomer mixture of 1 ) 45 to 96% by weight of at least one monoethylenically unsaturated C3 ,0 monocar-boxylic acid, 2) 4 to 55% by weight of at least one monoethylenically unsaturated monomer containing sulfonic acid groups, a monoethylenically unsaturated sulfuric acid ester and/or vinyl phosphonic acid, 3) 0 to 30% by weight of at least one water-soluble, monoethylenically unsaturated compound modified with 2 to 50 moles of alkylene oxide per mole, 4) 0 to 45% by weight of at least one other water-soluble, radical-polymerizable monomer, 5) 0 to 30% by weight of other water-soluble or substantially water-insoluble radical-polymerizable monomers, the sum of 1 ) to 5) being 100% by weight and the acids being replaceable by their salts with monovalent cations, in the presence of mono-, di- and oligosaccharides, reaction products and derivatives or mixtures thereof, the content of the saccharide components in the mixture as a whole being 5 to 60% by weight, b) polymers of 1 ) 10 to 70% by weight of monoethylenically unsaturated C4 8 dicarboxylic acids, 2) 20 to 85% by weight of monoethylenically unsaturated C310 monocarboxylic acids, 3) 1 to 50% by weight of monounsaturated monomers which, after hydrolysis or saponification, can be converted into monomer units with one or more hydroxyl groups covalently bonded to the C-C chain and 4) 0 to 10% by weight of other radical-copolymerizable monomers, the sum of 1 ) to 4) being 100% by weight and the acids being replaceable by their salts with monovalent cations, CA 022~2044 1998-10-09 c) naturally occurring polymers and derivatives thereof selected from polysaccharides, polyglycosides, polyglucosides, oxidized cellulose, oxidized starch, oxidized dextrin, proteins, d) organic polymers of which at least 80 mole-% consist of aspartic acid.
The graft copolymers of group a) are described in more detail in WO
94/01476 which is hereby specifically made part of the present disclosure.
According to this document, the following are preferably used: as monomers 1), acrylic acid and/or methacrylic acid, alkali metal, ammonium and/or amine salts thereof; as group 2) monomers, allyl sulfonic acid, methallyl sulfonic acid, acrylamidomethyl propane sulfonic acid, vinyl sulfonic acid, sulfatoethyl (meth)acrylate, vinyl phosphonic acid and/or salts of these acids with monomeric cations; as components 3), allyl alcohol or the esters of unsatu-rated carboxylic acids, such as acrylic acid or methacrylic acid, of which the alcohol component is modified with alkylene oxide; as component 4), molecular weight-increasing monomers and monomers containing mono-ethylenically polyunsaturated double bonds or an ethylenically unsaturated double bond and another functional crosslinking group. The polymerization is carried out as described in detail in the above-cited reference WO
94/01 476.
The group b) polymers suitable for use for the purposes of the invention are described in detail in DE-A 43 00 772 which is hereby specifically made part of the present disclosure. The components of these polymers are preferably selected from 1) maleic acid, itaconic acid and fumaric acid or salts thereof, 2) acrylic or methacrylic acid or salts thereof and 3) vinyl acetate, vinyl propionate and/or methyl vinyl ether.
Pure polyaspartic acids or copolymers containing aspartic acid, as CA 022~2044 1998-10-09 described for example in the literature cited at the beginning, are preferably used as organic polymers. In a preferred embodiment, at least 95 mole-%, preferably at least 98 mole-% and more preferably 100 mole-% of the organic polymers consist of aspartic acid. The average molecular weight, which may be determined for example by gel permeation chromatography in accordance with the above-cited WO 94/19409, is preferably in the range from about 1,000 to about 5,000. Preferably at least 50% and, more particularly, at least 70% of the polyaspartic acid or the polyaspartic acid component of the organic polymer is present in the so-called beta-form. The difference between the alpha-linkage and the beta-linkage is illustrated by formulae in the above-cited US-A-5,057,597. The distinction is based on whether the chemical bond to the adjacent monomer is in the alpha-position or the beta-position to the amide functions formed by the polycodensation.
The concentration of the organic polymers in the water phase of the water-based cooling systems is preferably adjusted to be in the range from about 1 to about 50 mg/l and more particularly in the range from about 5 to about 20 mg/l. The optimal concentration depends on the purity of the cooling water used. Accordingly, the expert will adapt the quantity used to the particular water quality by experimentation.
It is normal and preferred for the purposes of the invention for the water phase of the water-based cooling systems to contain other components which may have a corrosion-inhibiting or scale-inhibiting or dispersing effect.
Examples of such other components are zinc ions (1 to 10 mg/l), monomeric or oligomeric molybdate ions (1 to 200 mg/l), organic phosphates in such a concentration that the phosphorus content, expressed as phosphate, is between 1 and 20 mg/l phosphate, monomeric, oligomeric or polymeric inorganic phosphates in such a concentration that the phosphorus content, expressed as phosphate, is between 1 and 20 mg/l phosphate and non-ferrous metal inhibitors, for example triazoles. The water phase may contain - CA 022~2044 1998-10-09 known substances as further corrosion inhibitors, for example alkanolamines, more particularly triethanolamine, borates, sulfites, sorbitol, ascorbic acid, hydroquinone, hydroxyl amines, such as in particular N,N-diethyl hydroxyl-amine, nitrites, nitrates and silicates. Other corrosion-inhibiting and/or dispersing additives which may be used include phosphate esters, poly-phosphoric acid esters, aminophosphates, aminomethylene phosphoric acids, N-containing phosphates, more particularly aminoalkylene phosphonic acids, phosphonocarboxylic acids, succinic acid amide, gluconates, polyoxycarboxy-lic acids and copolymers thereof, tannin derivatives, lignin sulfonates, sulfonated condensation products of naphthalene with formaldehyde, polyacrylates, polymethacrylates, polyacrylamides, copolymers of acrylic or methacrylic acid and acrylamide, phosphinic acid-containing homopolymers and copolymers of acrylic acid and acrylamide, oligomeric phosphinosuccinic acid compounds, sulfomethylated or sulfoethylated polyacrylamides and copolymers or terpolymers with acrylic acid and maleic acid ester, N-butyl acrylamide and copolymers thereof, acrylamidopropionosulfonic acid and copolymers thereof, maleic anhydride polymers and copolymers, phosphino-alkylated acrylamide polymers and copolymers with acrylic acid, citric acid, ether carboxylates or oxidized carbohydrates.
In order to obtain optimal protection against corrosion, the water phase of the water-based cooling systems is preferably adjusted to a pH value in the range from about 7 to about 9. The biocidal oxidizing agent may be added to the cooling system either continuously or, preferably, discontinuously by batch treatment.
As mentioned at the beginning, the water-based cooling systems may be throughflow systems or open or closed circulation systems. The invention is designed in particular for use in open circulation systems because it is particularly suitable for counteracting the problems of scaling, deposit formation and/or biological contamination occurring in such systems.
CA 022~2044 1998-10-09 To determine the stability of polyaspartic acid in the presence of various known biocidal oxidizing agents, the scale-inhibiting effect of polyaspartic acid was tested as a function of time in the presence of the oxidizing agent. The polyaspartic acid selected was the product Donlar GS
Key components in the conditioning of cooling water include hardness stabilizers, dispersants, corrosion inhibitors and biocides. Examples of hardness stabilizers are inorganic polyphosphates, phosphonic acids, aminomethylene phosphonic acids, phosphoric acid esters, phosphono-carboxylic acids and polycarboxylic acids, for example of the partly saponified polyacrylamide type or the acrylic acid and/or methacrylic acid polymer or copolymer type. The polycarboxylic acids mentioned can also act as dispersants, in other words they stabilize microdispersed solid particles against ~edimentation and sludge formation. Apart from the partly hydrolyzed polyacrylamides and the acrylic acid and/or methacrylic acid polymers or copolymers mentioned, other suitable dispersants include polystyrene sulfonates, polyvinyl sulfonates, quaternary ammonium compounds, unsaponified polyacrylamides and polyalkylene glycols. Besides substances CA 022~2044 1998-10-09 which have a toxic effect on microorganisms, the microbicides used also include substances whose microbicidal effect is based on their oxidation potential. Oxidative microbicides have the disadvantage that they lose their effectiveness when they have oxidized other substances and have thus been exhausted. However, this disadvantage, which can be offset by continuous or periodic replenishment, is an advantage when the cooling water is completely or partly drained from the cooling system. Since oxidative microbicides are rapidly exhausted, they have generally become inactive by the time the cooling containing them enters the environment. Examples of oxidative microbicides are ozone, chlorine, bromine, chlorine dioxide, hypochlorites, hypobromites or hydrogen peroxide.
The organophosphorus compounds or organic polymers used as hardness stabilizers and/or as dispersants generally have the disadvantage that they are not biologically degradable. This lack of degradability is an advantage as long as these conditioning agents remain in the cooling circuit.
However, it becomes a disadvantage when the cooling medium is completely or partly drained off and enters the environment with or without any waste-water treatment. Accordingly, there is a need for hardness stabilizers and/or dispersants which show adequate biological degradability so that they can be rapidly biologically degraded at the latest when the cooling water to which they are added is drained from the cooling system.
Biologically degradable polymers suitable for use in the conditioning of water have recently been described. For example, WO 94/01476 relates to graft copolymers of unsaturated monomers and sugars, to processes for their production and to their use. The polymers described in this document consist of graft copolymers of monosaccharides, disaccharides and oligosaccharides, reaction products and derivatives thereof and a monomer mixture obtainable by radical graft copolymerization of a monomer mixture of 1 ) 45 to 96% by weight of at least one monoethylenically unsaturated C3 10 CA 022~2044 1998-10-09 monocarboxylic acid, 2) 4 to 55% by weight of at least one monoethylenically unsaturated monomer containing sulfonic acid groups, a monoethylenically unsaturated sulfuric acid ester and/or vinyl phosphonic acid, 3) 0 to 30% by weight of at least one water-soluble monoethylenically unsaturated compound modified with 2 to 50 moles of alkylene oxide per mole, 4) 0 to 45% by weight of at least one other water-soluble, radical-polymerizable monomer, 5) 0 to 30% by weight of other water-insoluble or substantially water-insoluble radical-polymerizable monomers, the sum of 1 ) to 5) being 100% by weight and the acids being replaceable by their salts with monovalent cations, in the presence of mono-, di- and oligosaccharides, reaction products and derivatives thereof or mixtures thereof, the content of the saccharide components in the mixture as a whole being from 5 to 60% by weight.
DE-A 43 00 772 also describes biologically degradable copolymers, a process for their production and their use. These biologically degradable copolymers are polymers of 1) 10 to 70% by weight of monoethylenically unsaturated C48 dicarboxylic acids, 2) 20 to 85% by weight of monoethy-lenically unsaturated C3 ,0 monocarboxylic acids, 3) 1 to 50% by weight of monounsaturated monomers which, after hydrolysis or saponification, can be converted into monomer units with one or more hydroxyl groups covalently bonded to the C-C chain and 4) 0 to 10% by weight of other radical-copoly-merizable monomers, the sum of 1 ) to 4) being 100% by weight and the acids being replaceable by their salts with monovalent cations.
Biologically degradable polymers suitable for use in the conditioning of water can also be found among naturally occurring polymers and derivatives thereof selected from polysaccharides, polyglycosides, poly-glucosides, oxidized cellulose, oxidized starch, oxidized dextrin, proteins.
In addition, polyaspartic acids and polymers containing aspartic acid have been proposed as biologically degradable polymers which may be used as dispersants or as scale inhibitors in the treatment of water. For example, CA 022~2044 1998-10-09 WO 94/19409 describes the production and use as dispersants of water-soluble salts of beta-polyaspartic acid, i.e. a polyaspartic acid in which most of the monomers are linked by beta-bonds. The average molecular weight is in the range from about 1,000 to about 5,000. In addition, it is apparent from WO 92/16462 that a polyaspartic acid obtained by hydrolysis of anhydro-aspartic acid is eminently suitable for preventing calcium carbonate and calcium phosphate scale. Other particulars of the synthesis of alpha- and beta-polyaspartic acid can be found in US-A-5,057,597. According to this document, the particulate monomeric amino acid is heated in a fluidized bed to a temperature of at least 180~C and is kept at a temperature of 180 to 250~C until the required degree of polymerization to anhydroaspartic acid is achieved with elimination of water. The anhydropolyaspartic acid is then hydrolyzed, preferably under alkaline conditions. An alternative method of production is described in WO 93/23452, according to which maleic acid is reacted with excess ammonia at temperatures of 200 to 300~C to form polyaspartic acid. The acid can be converted into its salts by reaction with a base.
WO 94/01486 describes modified polyaspartic acids, which may be used for example as water treatment agents, and processes for their production. These modified polyaspartic acids are obtained by polycon-densation of 1 to 99.9 mole-% of aspartic acid with 99 to 0.1 mole-% of fatty acids, polybasic carboxylic acids, monobasic polyhydroxycarboxylic acids, alcohols, amines, alkoxylated alcohols and amines, amino sugars, carbo-hydrates, sugar carboxylic acids and/or non-proteinogenic aminocarboxylic acids. The modified polyaspartic acids may also be prepared by radical-initiated graft copolymerization of monoethylenically unsaturated monomers in the presence of polyaspartic acids. In addition, WO 94/20563 describes a process for the production of reaction products of polyaspartic acid imides and amino acids and reaction products of polyaspartic acid imides with CA 022~2044 1998-10-09 alkanolamines or aminated fatty alcohol ethoxylates. Reaction products such as these are also suitable as scale inhibitors and as dispersants.
Other polymers and copolymers of aspartic acid, optionally in conjunction with other amino acids, are described for example in WO
92/17194, WO 94/03527, WO 94/21710 and DE-A-43 08 426. WO 94/19288 describes the use of polyaspartic acid and a large number of other products for preventing deposits in a building drainage system, for example in tunnels, galleries, concrete dams, dikes and the like. According to the teaching of EP-A-672 625, improved formulations for treating water are obtained by using polyaspartic acid or a derivative thereof in conjunction with a phosphonic acid.The ratio by weight of polyaspartic acid or derivative to phosphonic acid is preferably in the range from 90:10 to 10:90. The preferred polyaspartic acid is beta-polyaspartic acid with a molecular weight of 1,000 to 10,000.
Although the use of biologically degradable polymers, such as for example polyaspartic acid or other polymers containing polyaspartic acid, for the treatment of water is generally known from the literature cited above, the use of these biodegradable polymers at least in open cooling systems is problematical. The polymers can be expected to undergo rapid degradation in the cooling circuit itself, so that their effect is soon lost and their use is uneconomical. The problem addressed by the present invention was to stabilize these polymers against biological degradation in the cooling system without in any way impeding their degradation after leaving the cooling system. The prior-art literature does not contain any reference to the fact thatproducts of the type in question can be used together with biocidal oxidizing agents in cooling circuits. A potential application such as this appears doubfful because the oxidizing agents can be expected to react with and deactivate the polymers. By contrast, the present invention addressed the further problem of providing a combination of biodegradable polymers and biocidal oxidizing agents which could be used for conditioning water in cooling CA 022~2044 1998-10-09 circuits and which would remain active for a suffficiently long period under in-use conditions.
The problems stated above have been solved by the use of biologically degradable organic polymers with an average molecular weight above 500 in water-based cooling systems, characterized in that the water phase of the cooling systems additionally contains 0.05 to 5 mg/l of an oxidizing agent with a more positive standard redox potential than oxygen.
Standard redox potentials, also known as normal potentials, are generally known thermodynamic terms which are described in manuals of general or physical chemistry, cf. for example Chapter 11 of the manual: H.R.
Christen "Grundlagen der allgemeinen und anorganischen Chemie", Verlag Sauerlader-Salle, 1973. On pages 692 to 697, this manual contains a list of different normal potentials which can also be found in many other manuals and tabular works. The value of the standard redox potential is normally expressed in volts.
Oxidizing agents which a standard redox potential of > 0.4 volt are preferably used for the purposes of the present invention. This oxidizing agent is preferably selected from hydrogen peroxide, chlorine, bromine, chlorine dioxide, hypochlorites, hypobromites and ozone. Since these chemicals are capable of entering into acid-base and/or disproportionation reactions with water, the oxidizing agents mentioned above also include their reaction products with water.
Biological degradability can be measured by various methods. For example, it can be evaluated by the modified STURM Test (OECD Guideline No. 301 B) in which the quantity of carbon dioxide formed during degradation is measured. Alternatively, a modified MITI Test (OECD Guideline 301 for testing chemicals), in which the amount of oxygen consumed during degradation is measured, can be used. In the context of the present invention, polymers are regarded as biologically degradable if more than 50%
CA 022~2044 1998-10-09 degradation is observed after a test period of 28 days.
The biologically degradable polymers suitable for the purposes of the invention may be selected, for example, from a) graft copolymers of monosaccharides, disaccharides and oligosaccha-rides, reaction products and derivatives thereof and a monomer mixture obtainable by radical graft copolymerization of a monomer mixture of 1 ) 45 to 96% by weight of at least one monoethylenically unsaturated C3 ,0 monocar-boxylic acid, 2) 4 to 55% by weight of at least one monoethylenically unsaturated monomer containing sulfonic acid groups, a monoethylenically unsaturated sulfuric acid ester and/or vinyl phosphonic acid, 3) 0 to 30% by weight of at least one water-soluble, monoethylenically unsaturated compound modified with 2 to 50 moles of alkylene oxide per mole, 4) 0 to 45% by weight of at least one other water-soluble, radical-polymerizable monomer, 5) 0 to 30% by weight of other water-soluble or substantially water-insoluble radical-polymerizable monomers, the sum of 1 ) to 5) being 100% by weight and the acids being replaceable by their salts with monovalent cations, in the presence of mono-, di- and oligosaccharides, reaction products and derivatives or mixtures thereof, the content of the saccharide components in the mixture as a whole being 5 to 60% by weight, b) polymers of 1 ) 10 to 70% by weight of monoethylenically unsaturated C4 8 dicarboxylic acids, 2) 20 to 85% by weight of monoethylenically unsaturated C310 monocarboxylic acids, 3) 1 to 50% by weight of monounsaturated monomers which, after hydrolysis or saponification, can be converted into monomer units with one or more hydroxyl groups covalently bonded to the C-C chain and 4) 0 to 10% by weight of other radical-copolymerizable monomers, the sum of 1 ) to 4) being 100% by weight and the acids being replaceable by their salts with monovalent cations, CA 022~2044 1998-10-09 c) naturally occurring polymers and derivatives thereof selected from polysaccharides, polyglycosides, polyglucosides, oxidized cellulose, oxidized starch, oxidized dextrin, proteins, d) organic polymers of which at least 80 mole-% consist of aspartic acid.
The graft copolymers of group a) are described in more detail in WO
94/01476 which is hereby specifically made part of the present disclosure.
According to this document, the following are preferably used: as monomers 1), acrylic acid and/or methacrylic acid, alkali metal, ammonium and/or amine salts thereof; as group 2) monomers, allyl sulfonic acid, methallyl sulfonic acid, acrylamidomethyl propane sulfonic acid, vinyl sulfonic acid, sulfatoethyl (meth)acrylate, vinyl phosphonic acid and/or salts of these acids with monomeric cations; as components 3), allyl alcohol or the esters of unsatu-rated carboxylic acids, such as acrylic acid or methacrylic acid, of which the alcohol component is modified with alkylene oxide; as component 4), molecular weight-increasing monomers and monomers containing mono-ethylenically polyunsaturated double bonds or an ethylenically unsaturated double bond and another functional crosslinking group. The polymerization is carried out as described in detail in the above-cited reference WO
94/01 476.
The group b) polymers suitable for use for the purposes of the invention are described in detail in DE-A 43 00 772 which is hereby specifically made part of the present disclosure. The components of these polymers are preferably selected from 1) maleic acid, itaconic acid and fumaric acid or salts thereof, 2) acrylic or methacrylic acid or salts thereof and 3) vinyl acetate, vinyl propionate and/or methyl vinyl ether.
Pure polyaspartic acids or copolymers containing aspartic acid, as CA 022~2044 1998-10-09 described for example in the literature cited at the beginning, are preferably used as organic polymers. In a preferred embodiment, at least 95 mole-%, preferably at least 98 mole-% and more preferably 100 mole-% of the organic polymers consist of aspartic acid. The average molecular weight, which may be determined for example by gel permeation chromatography in accordance with the above-cited WO 94/19409, is preferably in the range from about 1,000 to about 5,000. Preferably at least 50% and, more particularly, at least 70% of the polyaspartic acid or the polyaspartic acid component of the organic polymer is present in the so-called beta-form. The difference between the alpha-linkage and the beta-linkage is illustrated by formulae in the above-cited US-A-5,057,597. The distinction is based on whether the chemical bond to the adjacent monomer is in the alpha-position or the beta-position to the amide functions formed by the polycodensation.
The concentration of the organic polymers in the water phase of the water-based cooling systems is preferably adjusted to be in the range from about 1 to about 50 mg/l and more particularly in the range from about 5 to about 20 mg/l. The optimal concentration depends on the purity of the cooling water used. Accordingly, the expert will adapt the quantity used to the particular water quality by experimentation.
It is normal and preferred for the purposes of the invention for the water phase of the water-based cooling systems to contain other components which may have a corrosion-inhibiting or scale-inhibiting or dispersing effect.
Examples of such other components are zinc ions (1 to 10 mg/l), monomeric or oligomeric molybdate ions (1 to 200 mg/l), organic phosphates in such a concentration that the phosphorus content, expressed as phosphate, is between 1 and 20 mg/l phosphate, monomeric, oligomeric or polymeric inorganic phosphates in such a concentration that the phosphorus content, expressed as phosphate, is between 1 and 20 mg/l phosphate and non-ferrous metal inhibitors, for example triazoles. The water phase may contain - CA 022~2044 1998-10-09 known substances as further corrosion inhibitors, for example alkanolamines, more particularly triethanolamine, borates, sulfites, sorbitol, ascorbic acid, hydroquinone, hydroxyl amines, such as in particular N,N-diethyl hydroxyl-amine, nitrites, nitrates and silicates. Other corrosion-inhibiting and/or dispersing additives which may be used include phosphate esters, poly-phosphoric acid esters, aminophosphates, aminomethylene phosphoric acids, N-containing phosphates, more particularly aminoalkylene phosphonic acids, phosphonocarboxylic acids, succinic acid amide, gluconates, polyoxycarboxy-lic acids and copolymers thereof, tannin derivatives, lignin sulfonates, sulfonated condensation products of naphthalene with formaldehyde, polyacrylates, polymethacrylates, polyacrylamides, copolymers of acrylic or methacrylic acid and acrylamide, phosphinic acid-containing homopolymers and copolymers of acrylic acid and acrylamide, oligomeric phosphinosuccinic acid compounds, sulfomethylated or sulfoethylated polyacrylamides and copolymers or terpolymers with acrylic acid and maleic acid ester, N-butyl acrylamide and copolymers thereof, acrylamidopropionosulfonic acid and copolymers thereof, maleic anhydride polymers and copolymers, phosphino-alkylated acrylamide polymers and copolymers with acrylic acid, citric acid, ether carboxylates or oxidized carbohydrates.
In order to obtain optimal protection against corrosion, the water phase of the water-based cooling systems is preferably adjusted to a pH value in the range from about 7 to about 9. The biocidal oxidizing agent may be added to the cooling system either continuously or, preferably, discontinuously by batch treatment.
As mentioned at the beginning, the water-based cooling systems may be throughflow systems or open or closed circulation systems. The invention is designed in particular for use in open circulation systems because it is particularly suitable for counteracting the problems of scaling, deposit formation and/or biological contamination occurring in such systems.
CA 022~2044 1998-10-09 To determine the stability of polyaspartic acid in the presence of various known biocidal oxidizing agents, the scale-inhibiting effect of polyaspartic acid was tested as a function of time in the presence of the oxidizing agent. The polyaspartic acid selected was the product Donlar GS
12-30 available from Donlar Corporation, 6502 S. Archer Ave., Bedford Park, IL 60501-9998, USA. The polymer has a molecular weight, as determined by gel permeation chromatography, of about 3,000 and a ratio of alpha- to beta-linkages of about 30:70. The polymer was used in a quantity of 10 mg/l in water adjusted to pH 8.5 with dilute sodium hydroxide or dilute sulfuric acid.
To this end, the oxidizing agent was added in a quantity of 0.4 mg/l, the oxidizing agents used in separate tests being a) sodium hypochlorite, b) chlorine dioxide, c) hydrogen peroxide, d) a mixture of sodium hypochlorite and sodium hypobromite in a ratio by weight of 1 :1.
The scale-inhibiting effect of the polyaspartic acid/oxidizing agent mixture was assessed immediately after addition of the oxidizing agent and then every 30 minutes up to a total test duration of 4 hours. The effectiveness test was carried out as follows. A test water containing 5.4 mmole/l calcium ions and 1.8 mmole/l magnesium ions was prepared. First the polyaspartic acid/oxidizing agent mixture and then 20 mmole/l sodium hydrogen carbonate were added to the test water. Using a flow inducer, the test solution was pumped at a rate of 0.5 I/h through the glass coil of a glass condenser in the outer space of which circulated water heated to a temperature of 80~C. After a test period of 2 hours, the glass condenser was emptied and the hardness deposit formed was removed with hydrochloric acid. The content of hardness ions in the hydrochloric acid solution was determined by titrimetry. The scale-inhibiting effect of the test mixture is better, the smaller the number of hardness ions present in the hydrochloric acid solution. The beginning of the two-hour test was taken as the test time.
The tests showed that, where sodium hypochlorite, chlorine dioxide or - CA 022~2044 1998-10-09 hydrogen peroxide was used, there was no measurable deterioration in the scale-inhibiting effect over the four hour test period. Where mixture d) was used, around 95% of the initial effectiveness was still present after four hours.
The chlorine stability of another two biodegradable polymers was similarly tested: an anionically modified graft copolymer (product W 70280 according to DE-A 42 21 381, supplier: Stockhausen, Germany) and an acrylic acid/maleic acid/vinyl alcohol terpolymer (product W 71409 according to DE-A-43 00 772, supplier: Stockhausen, Germany). The first polymer was dissolved in water in a concentration of 5 ppm and the second in a concen-tration of 15 ppm and the pH was adjusted to a value of 8.5. The solutions were then divided. Chlorine was added to half of each divided solution in a quantity of 0.4 mg/l. After four hours, the scale-inhibiting effect of these solutions was tested by the method described above. No difference was found between the scale-inhibiting effects of the chlorine-containing solution and the chlorine-free solution. Accordingly, the polymers are stable to chlorine.
The degradation behavior of polyaspartic acid with and without an added oxidizing agent (sodium hypochlorite) was studied for one month in a cooling tower. Between 20 and 50 mg/l of polyaspartic acid were added daily and the actual polyaspartic acid content of the cooling circuit was determined before each addition. This was done by precipitating the polyaspartic acid from a sodium citrate-buffered solution with a cationic surfactant (Hyamin 1622, Rohm & Hass). This resulted in clouding which was photometrically determined and compared with a calibration curve.
During the first two test weeks, the quantities of polyaspartic acid actually found decreased continuously despite replenishment and were in the range from about 11 to about 2 mg/l. After two weeks with daily additions of 30 to 40 mg/l polyaspartic acid, 0.2 mg/l chlorine in the form of sodium hypochlorite was additionally introduced. The content of measurable CA 022~2044 1998-10-09 polyaspartic acid in the cooling circuit increased in two days to around 20 mg/land remained at that level for the remainder of the test. Accordingly, the degradation of the polyaspartic acid in the cooling circuit was distinctly reduced by the additional introduction of sodium hypochlorite.
To this end, the oxidizing agent was added in a quantity of 0.4 mg/l, the oxidizing agents used in separate tests being a) sodium hypochlorite, b) chlorine dioxide, c) hydrogen peroxide, d) a mixture of sodium hypochlorite and sodium hypobromite in a ratio by weight of 1 :1.
The scale-inhibiting effect of the polyaspartic acid/oxidizing agent mixture was assessed immediately after addition of the oxidizing agent and then every 30 minutes up to a total test duration of 4 hours. The effectiveness test was carried out as follows. A test water containing 5.4 mmole/l calcium ions and 1.8 mmole/l magnesium ions was prepared. First the polyaspartic acid/oxidizing agent mixture and then 20 mmole/l sodium hydrogen carbonate were added to the test water. Using a flow inducer, the test solution was pumped at a rate of 0.5 I/h through the glass coil of a glass condenser in the outer space of which circulated water heated to a temperature of 80~C. After a test period of 2 hours, the glass condenser was emptied and the hardness deposit formed was removed with hydrochloric acid. The content of hardness ions in the hydrochloric acid solution was determined by titrimetry. The scale-inhibiting effect of the test mixture is better, the smaller the number of hardness ions present in the hydrochloric acid solution. The beginning of the two-hour test was taken as the test time.
The tests showed that, where sodium hypochlorite, chlorine dioxide or - CA 022~2044 1998-10-09 hydrogen peroxide was used, there was no measurable deterioration in the scale-inhibiting effect over the four hour test period. Where mixture d) was used, around 95% of the initial effectiveness was still present after four hours.
The chlorine stability of another two biodegradable polymers was similarly tested: an anionically modified graft copolymer (product W 70280 according to DE-A 42 21 381, supplier: Stockhausen, Germany) and an acrylic acid/maleic acid/vinyl alcohol terpolymer (product W 71409 according to DE-A-43 00 772, supplier: Stockhausen, Germany). The first polymer was dissolved in water in a concentration of 5 ppm and the second in a concen-tration of 15 ppm and the pH was adjusted to a value of 8.5. The solutions were then divided. Chlorine was added to half of each divided solution in a quantity of 0.4 mg/l. After four hours, the scale-inhibiting effect of these solutions was tested by the method described above. No difference was found between the scale-inhibiting effects of the chlorine-containing solution and the chlorine-free solution. Accordingly, the polymers are stable to chlorine.
The degradation behavior of polyaspartic acid with and without an added oxidizing agent (sodium hypochlorite) was studied for one month in a cooling tower. Between 20 and 50 mg/l of polyaspartic acid were added daily and the actual polyaspartic acid content of the cooling circuit was determined before each addition. This was done by precipitating the polyaspartic acid from a sodium citrate-buffered solution with a cationic surfactant (Hyamin 1622, Rohm & Hass). This resulted in clouding which was photometrically determined and compared with a calibration curve.
During the first two test weeks, the quantities of polyaspartic acid actually found decreased continuously despite replenishment and were in the range from about 11 to about 2 mg/l. After two weeks with daily additions of 30 to 40 mg/l polyaspartic acid, 0.2 mg/l chlorine in the form of sodium hypochlorite was additionally introduced. The content of measurable CA 022~2044 1998-10-09 polyaspartic acid in the cooling circuit increased in two days to around 20 mg/land remained at that level for the remainder of the test. Accordingly, the degradation of the polyaspartic acid in the cooling circuit was distinctly reduced by the additional introduction of sodium hypochlorite.
Claims (12)
1. The use of biologically degradable organic polymers with an average molecular weight above 500, which have a biological degradability of more than 50% after a test period of 28 days, in water-based cooling systems, characterized in that the water phase of the cooling systems additionally contains 0.05 to 5 mg/l of an oxidizing agent with a more positive standard redox potential than oxygen.
2. The use claimed in claim 1, characterized in that the organic polymers are selected from a) graft copolymers of monosaccharides, disaccharides and oligosaccharides, reaction products and derivatives thereof and a monomer mixture obtainable by radical graft copolymerization of a monomer mixture of 1) 45 to 96% by weight of at least one monoethylenically unsaturated C3-10 monocarboxylicacid, 2) 4 to 55% by weight of at least one monoethylenically unsaturated monomer containing sulfonic acid groups, a monoethylenically unsaturated sulfuric acid ester and/or vinyl phosphonic acid, 3) 0 to 30% by weight of at least one water-soluble, monoethylenically unsaturated compound modified with 2 to 50 moles of alkylene oxide per mole, 4) 0 to 45% by weight of at least one other water-soluble, radical-polymerizable monomer, 5) 0 to 30% by weight of other water-soluble or substantially water-insoluble radical-polymerizable monomers, the sum of 1) to 5) being 100% by weight and the acids being replaceable by their salts with monovalent cations, in the presence of mono-, di- and oligosaccharides, reaction products and derivatives or mixtures thereof, the content of the saccharide components in the mixture as a whole being 5 to 60% by weight, b) polymers of 1) 10 to 70% by weight of monoethylenically unsaturated C4-8 dicarboxylic acids, 2) 20 to 85% by weight of monoethylenically unsaturated C3-10 monocarboxylic acids, 3) 1 to 50% by weight of monounsaturated monomers which, after hydrolysis or saponification, can be converted into monomer units with one or more hydroxyl groups covalently bonded to the C-C chain and 4) 0 to 10% by weight of other radical-copolymerizable monomers, the sum of 1) to 4) being 100% by weight and the acids being replaceable by their salts with monovalent cations, c) naturally occurring polymers and derivatives thereof selected from polysaccharides, polyglycosides, polyglucosides, oxidized cellulose, oxidized starch, oxidized dextrin, proteins, d) organic polymers of which at least 80 mole-% consist of aspartic acid.
3. The use claimed in one or both of claims 1 and 2, characterized in that the standard redox potential of the oxidizing agent is greater than 0.4 volt.
4. The use claimed in one or more of claims 1 to 3, characterized in that the oxidizing agent is selected from hydrogen peroxide, chlorine, bromine, chlorine dioxide, hypochlorites, hypobromites and ozone or their reaction products with water.
5. The use claimed in one or more of claims 1 to 4, characterized in that organic polymers of group d) of which at least 95 mole-% consists of aspartic acid are used.
6. The use claimed in claim 5, characterized in that the organic polymers have an average molecular weight of 1,000 to 5,000.
7. The use claimed in one or both of claims 5 and 6, characterized in that at least 50% of the polyaspartic acid component of the organic polymers is present in the beta-form.
8. The use claimed in one or more of claims 1 to 7, characterized in that the concentration of the organic polymers in the water phase of the aqueous cooling systems is in the range from 1 to 50 mg/l.
9. The use claimed in claim 8, characterized in that the concentration of the organic polymers in the water phase of the water-based cooling systems is in the range from 5 to 20 mg/l.
10. The use claimed in one or more of claims 1 to 9, characterized in that the water phase of the water-based cooling systems additionally contains one or more of the following components: zinc ions (1 to 10 mg/l), monomeric or oligomeric molybdate ions (1 to 200 mg/l), organic phosphates in such a concentration that the phosphorus content, expressed as phosphate, is between 1 and 20 mg/l phosphate, monomeric, oligomeric or polymeric inorganic phosphates in such a concentration that the phosphorus content, expressed as phosphate, is between 1 and 20 mg/l phosphate, alkanolamines, borates, sulfites, sorbitol, ascorbic acid hydroquinone, hydroxylamines, nitrites, nitrates, silicates, monomeric, oligomeric or polymeric carboxylic acids with a chelating effect, amides or esters thereof, tannin derivatives, lignin sulfonates, sulfonated naphthalene/formaldehyde condensates and/or non-ferrous metal inhibitors.
11. The use claimed in one or more of claims 1 to 10, characterized in that the water phase of the water-based cooling systems has a pH value of 7 to 9.
12. The use claimed in one or more of claims 1 to 11, characterized in that the cooling systems are open circulation systems.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19614565.1 | 1996-04-12 | ||
| DE19614565A DE19614565A1 (en) | 1996-04-12 | 1996-04-12 | Use of aspartic acid-containing polymers in cooling circuits mixed with biocides |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2252044A1 true CA2252044A1 (en) | 1997-10-23 |
Family
ID=7791139
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
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| CA002252044A Abandoned CA2252044A1 (en) | 1996-04-12 | 1997-04-04 | Use of aspartic acid-containing polymers in cooling circuits with added biocides |
Country Status (13)
| Country | Link |
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| EP (1) | EP0892838B1 (en) |
| AT (1) | ATE202593T1 (en) |
| AU (1) | AU2383697A (en) |
| BG (1) | BG102828A (en) |
| CA (1) | CA2252044A1 (en) |
| CZ (1) | CZ290664B6 (en) |
| DE (2) | DE19614565A1 (en) |
| ES (1) | ES2160344T3 (en) |
| HU (1) | HU224064B1 (en) |
| PL (1) | PL188818B1 (en) |
| SK (1) | SK139498A3 (en) |
| TR (1) | TR199802040T2 (en) |
| WO (1) | WO1997039078A1 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10280520B2 (en) | 2014-08-08 | 2019-05-07 | Nch Corporation | Composition and method for treating white rust |
| US10351453B2 (en) | 2016-04-14 | 2019-07-16 | Nch Corporation | Composition and method for inhibiting corrosion |
| US11085118B2 (en) | 2016-04-14 | 2021-08-10 | Nch Corporation | Composition and method for inhibiting corrosion and scale |
| US11104587B2 (en) | 2016-04-14 | 2021-08-31 | Nch Corporation | System and method for automated control, feed, delivery verification, and inventory management of corrosion and scale treatment products for water systems |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19721346A1 (en) * | 1997-05-22 | 1998-11-26 | Henkel Kgaa | Use of aspartic acid-containing polymers together with hydroxycarboxylic acids to inhibit corrosion in cooling circuits |
| DE19834226C1 (en) * | 1998-07-29 | 2000-02-10 | Excor Korrosionsforschung Gmbh | Vapor phase corrosion inhibitors, processes for their production and their use |
| DE19837068A1 (en) | 1998-08-17 | 2000-02-24 | Bayer Ag | Water treatment composition, especially for use in cooling circuits, comprises polyaspartic acid, biocidal oxidizing agent and sulfamic acid stabilizer |
| DE10228628A1 (en) * | 2002-06-26 | 2004-01-22 | Stockhausen Gmbh & Co. Kg | Copolymers to avoid deposits in water-bearing systems, their production and use |
| RU2008126444A (en) * | 2005-12-02 | 2010-01-10 | Басф Се (De) | CHEMICAL COMPOSITION APPLICABLE AS A CORROSION INHIBITOR |
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| NL297360A (en) * | 1962-09-04 | |||
| DE4221381C1 (en) * | 1992-07-02 | 1994-02-10 | Stockhausen Chem Fab Gmbh | Graft copolymers of unsaturated monomers and sugars, process for their preparation and their use |
| DE4221875A1 (en) * | 1992-07-03 | 1994-01-05 | Basf Ag | Modified polyaspartic acids, process for their preparation and their use |
| DE4300772C2 (en) * | 1993-01-14 | 1997-03-27 | Stockhausen Chem Fab Gmbh | Water-soluble, biodegradable copolymers based on unsaturated mono- and dicarboxylic acids, process for their preparation and their use |
| DE9416521U1 (en) * | 1993-02-17 | 1995-05-24 | Nalco Chemie Gmbh Deutsche | Arrangement for preventing deposits in a building drainage system |
| DE4408478A1 (en) * | 1994-03-14 | 1995-09-21 | Bayer Ag | Water treatment agents |
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1996
- 1996-04-12 DE DE19614565A patent/DE19614565A1/en not_active Withdrawn
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1997
- 1997-04-04 CA CA002252044A patent/CA2252044A1/en not_active Abandoned
- 1997-04-04 AU AU23836/97A patent/AU2383697A/en not_active Abandoned
- 1997-04-04 AT AT97919319T patent/ATE202593T1/en active
- 1997-04-04 WO PCT/EP1997/001690 patent/WO1997039078A1/en active IP Right Grant
- 1997-04-04 HU HU9903607A patent/HU224064B1/en active IP Right Grant
- 1997-04-04 PL PL97329242A patent/PL188818B1/en unknown
- 1997-04-04 SK SK1394-98A patent/SK139498A3/en unknown
- 1997-04-04 DE DE59703910T patent/DE59703910D1/en not_active Expired - Lifetime
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- 1997-04-04 EP EP97919319A patent/EP0892838B1/en not_active Expired - Lifetime
- 1997-04-04 CZ CZ19983274A patent/CZ290664B6/en not_active IP Right Cessation
- 1997-04-04 TR TR1998/02040T patent/TR199802040T2/en unknown
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- 1998-10-09 BG BG102828A patent/BG102828A/en unknown
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10280520B2 (en) | 2014-08-08 | 2019-05-07 | Nch Corporation | Composition and method for treating white rust |
| US10351453B2 (en) | 2016-04-14 | 2019-07-16 | Nch Corporation | Composition and method for inhibiting corrosion |
| US11085118B2 (en) | 2016-04-14 | 2021-08-10 | Nch Corporation | Composition and method for inhibiting corrosion and scale |
| US11104587B2 (en) | 2016-04-14 | 2021-08-31 | Nch Corporation | System and method for automated control, feed, delivery verification, and inventory management of corrosion and scale treatment products for water systems |
| US11661365B2 (en) | 2016-04-14 | 2023-05-30 | Nch Corporation | Composition and method for inhibiting corrosion |
Also Published As
| Publication number | Publication date |
|---|---|
| DE59703910D1 (en) | 2001-08-02 |
| EP0892838A1 (en) | 1999-01-27 |
| HU224064B1 (en) | 2005-05-30 |
| BG102828A (en) | 1999-08-31 |
| SK139498A3 (en) | 1999-04-13 |
| HUP9903607A2 (en) | 2000-04-28 |
| TR199802040T2 (en) | 1999-01-18 |
| AU2383697A (en) | 1997-11-07 |
| CZ327498A3 (en) | 1999-03-17 |
| WO1997039078A1 (en) | 1997-10-23 |
| EP0892838B1 (en) | 2001-06-27 |
| PL329242A1 (en) | 1999-03-15 |
| HUP9903607A3 (en) | 2003-07-28 |
| ATE202593T1 (en) | 2001-07-15 |
| PL188818B1 (en) | 2005-04-29 |
| ES2160344T3 (en) | 2001-11-01 |
| DE19614565A1 (en) | 1997-10-16 |
| CZ290664B6 (en) | 2002-09-11 |
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