CA1332138C - Treatment of aqueous systems - Google Patents
Treatment of aqueous systemsInfo
- Publication number
- CA1332138C CA1332138C CA000521449A CA521449A CA1332138C CA 1332138 C CA1332138 C CA 1332138C CA 000521449 A CA000521449 A CA 000521449A CA 521449 A CA521449 A CA 521449A CA 1332138 C CA1332138 C CA 1332138C
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- Prior art keywords
- acid
- zinc
- composition according
- weight
- chelant
- Prior art date
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Classifications
-
- 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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- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
- Silver Salt Photography Or Processing Solution Therefor (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Chemical Treatment Of Metals (AREA)
Abstract
ABSTRACT
THE TREATMENT OF AQUEOUS SYSTEMS
A method of treating an aqueous system is disclosed which comprises adding thereto a water-soluble zinc salt, a chelant and either a product containing at least one phosphorus-containing acid group and at least one carboxylic acid group or an acrylic, vinyl or allyl carboxylic acid polymer.
THE TREATMENT OF AQUEOUS SYSTEMS
A method of treating an aqueous system is disclosed which comprises adding thereto a water-soluble zinc salt, a chelant and either a product containing at least one phosphorus-containing acid group and at least one carboxylic acid group or an acrylic, vinyl or allyl carboxylic acid polymer.
Description
~332~3,3 ~ -THE TREATMENT OF AQUEOUS SYSTEMS
The present invention relates to the treatment of aqueous systems and, more particularly, to reducing or eliminating corrosion in asueous systems.
Many different types of material have been employed to prevent or inhibit corrosion in aqueous systems. These include inorganic salts such as nitrites and chromates, inorganic mono and polyphosphates, certain water soluble polymers including naturally occurring materials such as lignins and starches as well as synthetic materials such as polyacrylates, as well as organic phosphonates. In addition, it is well known to use zinc salts for this -~
purpose. Indeed, it is known to use zinc salts in combination with organic type corrosion inhibitors, principally organic phosphonates and polyacrylates.
: ~ :
The u~e of zinc salts enables one to passivate corrosion of the metal in contact with the system. It is generally ~;,,;
believed that localised high concentrations of hydroxide ions arise at sites of corrosion on the metal surface because, due to the galvanic cell effect, oxygen present -~
in the water is reduced to hydroxide ions at the ca hodic sites. These hydroxide ions then react with zinc ions of - -~ the zinc salt to give zinc hydroxide which in turn yields - a protective film on the metal surface.
While this pas6ivation system works reasonably sati8factorily in some aqueous media it is known that the use of zinc salt~, with or wlthout the organic type corrosion inhibitor, is ineffective when the pH of the system is high, for example at pH from 8.2 to 9Ø Such a -~
pH can be pre~ent when the water is hard, or is otherwise ~ \
- ~ 332:~ 3~
alkaline ie of low hardness and high alkalinity as can be the case with base exchanged water. Under such circumstances, the zinc hydroxide precipitates prematurely in the system water and therefore does not form a protective film over the metal. Thus in such systems the zinc actually becomes a foulant of the system. Similar problems arise when th~ temperature of the aqueous system i5 raised, for example to at least 40C as can occur when the aqueous system is used as cooling water which comes into contact with hot metal surfaces.
It has now surprisingly been found, according to the present invention, that ~ore effective corrosion inhibition can be obtained when a zinc salt is used together with a class of phosphonate or similar material and, in addition, a chelant. It has been found that this combination is capable of being effective under a combination of severe pH and temperature conditions. It is considerably more effective than existing zinc/organic products on pre-corroded mild steel surfaces since the combination is capable of stifling existing corrosion as ;~ well as enabling much faster passivation of the rusty surface to be brought about. Thus the combination, as well as inhibiting corrosion, also acts as an on line cleaning agent by removing old rust.
, According to the present invention there is provided a method of treating an aqueous system which comprises adding thereto a zinc salt, a chelant and either a product containing ~t least one phosphorus-containing acid group and at least one carboxylic acid group or an acrylic, vinyl or allyl carboxylic acid polymer.
Generally, any water soluble zinc salt can be used in the present invention. Typical salts which can be used ..... .
include zinc sulphate, zinc chloride, zinc nitrate and zinc acetate, zinc sulphate monohydrate and zinc chloride being particularly preferred. -The third component used in the present invention will, in S general, be a phosphonate. Preferably, the materials used contain at least two acid groups, one of which is a phoæphonate group and the other is a carboxylic acid group, at least the two said acid groups being attached to ~
carbon atoms. , 10 Preferred phosphonates include hydroxy phosphonoacetic ~,~
;~ acid and 2-phosphono butane-1,2,4-tricarboxylic acid, the ~ h latter being particularly preferred. Thus these preferred ; ~ phosphonates possess the general formula O R
~ 0 ) 2P f COOH
~ H2 - COOH
, " . ~ , .,,:
~ 15 wherein R is hydrogen, alkyl, alkenyl or alkynyl having up .~ to 4 carbon atoms; phenyl; cycloalkyl having 3 to 6 carbon ~`
atoms; benzyl; phenethyl or ~ -R' ~"
CH ~ R
wherein R' is hydrogen, alkyl having 1 to 4 carbon atoms or carboxyl, Ra is hydrogen or methyl and R''' is carboxyl or phosphonate. ~
, , ,:
'.:., ''' :'`' .
.
-:
~ 3321:~
It is also possible to employ as the third component in the method a polymeric material and, in particular, carboxylic acid polymers which contain a chain phosphorus atom which forms part of an acid group. Thus these polymeric materials are preferably phosphino polycarboxylic acids, typically those having the formula Hf -- CH~p~/H2 -- I H~ :~
~ HOOC J ~H ~ COOH
where N + M = 4 to 20 The molecular weight of such polymers is relatively low, generally below 5,000, the preferred molecular weight being from 250 to 750, especially about 500. A
particularly suitable polymer is that sold as ~Belclene 500" by Ciba-Geigy.
~' It has also been found that a synergistic effect, although most pronounced when the phosphorus containing materials ` are used, can also be obtained when a polycarboxylic acid - ~; is uæed, typically one having a molecular weight from 1,000 to 5,000. Such polymers may be derived from acrylic, vinyl or allyl carboxylic monomers, typically acrylic, methacrylic, maleic, fumaric, itaconic, crotonic or ~innamic acid alone or with a suitable comonomer. Such comonomers include acrylamide, (meth)acrylate esters or hydroxy esters e.g. hydroxypropyl esters, vinyl pyrrolidone, vinyl acetate, acrylonitrine, ~inyl methyl ether, 2-acrylamido-2-methyl-propane sulphonic acid, vinyl or allyl ~ulphonic acid and styrene sulphonic acid as well as cationic monomers such as diallyl dimethyl ammonium chloride, dimethylamino ethylacrylate or methacrylate, optionally quaternised with, for example, dimethyl J ~ :
,''''~`~.
``` ' ~33~13g ' s~lphate or methyl chloride.
i The chelants which can be used in the method of the present invention are generally compounds with a nitrogen ligand which are effective chelants for iron Usually, these chelants will also possess a carboxylic acid group.
A preferred group of chelants possesses the formula ;
R3 - ~ - CH - R2 where Rl is hydrogen, hydroxyethyl or carboxymethyl, preferably carboxymethyl, R2 ~s hydrogen, hydroxyphenyl, ~-~
preferably ortho-hydroxyphenyl, which is optionally methyl or sulphonic acid substituted, or carboxyl, R4 is hydrogen or carboxyl, ~
Rl R4 -R is - X - N - CH - R , -CH2CH20H, R1~4 -CH2C6H~(OH)(S03H) or -CH2C6H2(OH)~CH3)CH2~-N-R
where R , R2 and R4 are as defined above and X is -(CH2)2- or - ~CH2)3 -~ The phenyl groups may be substituted, if desired, preferably by one or more halogen atoms. `~
: ~ ' , ~-`,' If the chelant is to be used in aqueous systems which 20 possess a high pH and a relatively high temperature it is ~
preferred that at least one of Rl, R2 and R3 contains a -~`
`~ hydroxyl group. Thus the most preferred chelants possess a nitrogen ligand, a carboxylic acid group and a hydroxyl ~ group~
; ~ 25l Preferred chelants for use in t~e present invention include N~N'-di(-2-hydroxybenzyl-)trimethylened1amine-N, N'-diacetic acid, N,N'ethylene-bis-[2-(2-hydroxy-4-methyl-phenyl)-glycine], ethylenediamine N, N'-bis-[2-hydroxyphenylacetic acid] and N, 30 N-di(2-hydroxy-5-sulphonic acid benzyl~glycine which is A ;~
~;
~ 3~2i~8 especially preferred not only on account of its effectiveness but also on account of its excellent solubility properties which faciliate the formulation of compositions, as well as N,N-di(2-hydroxyethyl) glycine, S N-hydroxyethyl N,N',N'-ethylenediamine triacetic acid and 2-hydroxyethyl iminodiacetic acid. Ethylenediamine tetraacetic acid and diethylene triamine pentaacetic acid can also be mentioned although they are less preferred since they do not contain a hydroxyl group (other than as part of the carboxylic acid groups).
In general, from 1 to 10 parts by weight of chelant and from 4 to 6 parts by weight of the phosphorus containing compound are employed to 1 part of the zinc salt. While in certain circumstances it may be desirable to add the individual components separately, in other situations it will be convenient to add the components together in the form of a composition. Accordingly, the present invention also provides a composition suitable for addition to an aqueous system which comprises a water ~-soluble zinc salt, a product containing at least one phosphorus containing acid group and at least one carboxylic acid group or an acrylic, vinyl or allyl carboxylic acid polymer, and a chelant. In such a situation, it may be desirable to add further quantities of chelant as required~ Typically, the composition will be an aqueous formulation containing, generally, 1% to 2%
by weight Qf zinc salt (as zinc), 4~ to 10% by weight of the phosphorus containing material or polymer and 1~ to ' 25~ by weight, especially about 5% by weight, of the ;~
; 30 chelant.
A further surprising feature of the present invention is that the presence of the combination of chelant and phosphorus conta~ning compound and/or acrylic vinyl or ~332~
- 7 - ~-allyl carboxylic acid polymer enables one to reduce the amount of zinc salt. It is usual in the art to employ amounts of the order of 2 to 5ppm zinc. However, with ever increasing restrictions on concentrations of zinc in discharges there is a constant demand to reduce the amounts of zinc used. It has been found that by using the additional ingredients it is possible to reduce the amount of zinc to, say, about lppm for comparable effectiveness.
In such circumstances it is preferred to employ about 4ppm of the phosphorus compound and about 2.5 to 5ppm of chelant. If, on the other hand, one usès 2.5ppm of zinc then it is preferred to use about lOppm of phosphorus compound and about 5ppm of chelant.
.
It is also possible to use the combination of the present invention together with other ingredients including phosphates, biocides, yellow metal corrosion inhibitors such as benzotriazole and tolyltriazole as well as other ;
;~ polymers which act as dispersants such as polyacrylic 1~ acid, polymaleic acid and copolymers of maleic acid with l 20 styrene sulphonic acid. In particular, it has been found ¦~ that the use of certain disper~ants, especially a ~ ;~
¦~ copolymer of methacrylic acid and acrylamide is particularly advantageous, especially one in which the mole ratio is about 1:3, and further enhances the corrosion protection given by the three component system.
In general the molecular weight of the homopolymers will be 1,000 to lO,000 while that of the copolymers will be l,000 to 50,000.
The use of a phosphate is particularly noteworthy since zinc phosphate i9 effective in low water hardness systems because the zinc phosphate itself gives protection. By using the chelant and phosphorus containing compound as -~
well it is possible, as previously discussed, to use ., ~ ~ 33~ 3~
, significantly lower quantities of zinc.
The following Examples further illustrate the present invention.
Examples 1 to 34 In these Examples tests were carried out on a laboratory scale recirculating rig consisting of a plastic vessel holding 8 litres of water and connected by tubing to a ¦~; circulating pump the water passing from the pump through a glass rack holding the metal test coupons ('line') and returning to the plastic vessel. Any evaporation was made ~ up by the addition of de-ionised water. Metal test I coupons were also suspended in the plastic vessel ('Pond'). ~he corrosion rate was calculated from the -weight of metal lost during test. The water temperature was maintained by means of a heater/thermostat arrangement. The conditions of the test were as follows:
System Water : 150ppm Ca hardness/150ppm 'M' Alkalinity Water pH : 8.8 ~; 20 ~Water Temperature : 54 C or 40C ~as stated) Flow Rate : Line : 2 ft/sec `~
Pond : 0.2 ft/sec Duration of Test : 3 days Tnitial Passivation : 1 day at 3 times normal ; 25~ maintenance dose.
Examples No. 1 - 14 were carried out at 40C.
'"';''.:`
. ''' '' '.~
133~1~8 Example Additive Dose, ppm Corrosion of -No. Mild Steel in mils per year (mpy) :
Line Pond No addition :~ 2 Zinc/Chelant 1/~ - 2.2/5/--- 5.7 12.9 3 Zinc/Chelant l/Phosphonate 1 2.2/5/8.8 1.0 0.9 4 zinc,~ /Phosphonate 1 2.2/-/8.8 7.8 3.3 ~; 10 5 Zinc/Chelant 2/------- 2.2/5/---1.1 8.8 ~: 6 Zinc/Chelant 2/Phosphonate 1 2.2/5/8.8 0.2 0.3 --. ~: 7 Zinc/Chelant 3/~ -- 2.2/5/--- 1.5 2.4 . -:
8 Zinc/Chelant 3/Phosphonate 1 2.2/5/8.8 1.1 1.6 9 Zinc/Chelant 4/------- 2.2/5/---9.0 . 7.3 -~.~
Zinc/Chelant 4/Phosphonate 1 2.2/5/8.8 0.3 0.7 .` ;
11 Zinc/Chelant 5/------- 2.2/5/---10.7 12.9 12 Zinc/Chelant 5/Phosphonate 1 2.2/5/8.8 1.9 8.6 :~
;13 Zinc/Chelant 2/Phosphonate 2 2.2/5/8.8 4.5 4.8 ;:
14 Zinc/Chelant 9/Phosphonate 1 2.2/5/8.8 0.2 0.2 .
20~ ~;Examples 1 - 14 illustrate:
he blend of z`i~n~/chelant/phosphonate is superior to zinc/phosphonate or zinc/chelant.
The~prefer;red ~chelants are Chelants 1, 2,3 and 9.
$ii~ Phosphonate l :gives significantly better results ~-25 :~ than~comparative Phosphonate 2.
Examples l5 - 34 were carried out at 54C.
15 Zinc/Chelant 2/Phosphino 1 2.2/5/8.82.9 5.3 16~::Z:inc,~Chelant 2/Phosphino 1 2.5/5/10.0 1.2 3.1 `; 17 ~Zinc/~ Phosphino 1 2.2/-/8.810.5 11.7 ~:
: 30 18 Zinc/Chelant 2/Phosphonate 1 2.2/5/5 0.5 1.6 ~ `~
19 Zinc/Chelant 2/Phosphonate 1 2.2/5/8.8 0.5 1.4 .::
., , :',; .
' " ~
~',' 13~2~3 Zinc/Chelant 2/Phosphonate 1/
Polymer 1 2.2/5/8.8/2.5 0.4 0.9 21 Zinc/Chelant 2/Phosphonate 3 2.2/5/8.8 0.4 0.5 22 Zinc/Chelant l/Phosphonate 1 2.2/5/8.8 1.2 5.0 23 Zinc/Chelant 4/Phosphonate 1 2.2/5/8.8 2.3 5.6 24 Zinc/Chelant 3/Phosphonate 1 2.2/5/8.8 1.6 2.4 Zinc/Chelant 3/Phosphonate 1 1/5/4.4 2.1 5.2 26 Zinc/Chelant 2/Polymer 22.2/5/10 5.2 9.1 27 Zinc/~ /Polymer 2 2.2/-/10 21.4 21.3 28 Zinc/Chelant 2/Polymer 32.2/5/107.2 9.7 29 Zinc/-~ /Polymer 3 2.2/-/10 17.7 32.2 Zinc/Chelant 6/Phosphonate 1 2.2/5/8.8 3.1 3.4 31 Zinc/Chelant 7/Phosphonate 1 2.2/5/8.8 3.2 2.1 32 Zinc/Chelant 8/Phosphonate 1 2.2/5/8.8 3.6 6.8 33 Zinc/------ /Phosphonate 12.2/-/8.8 9.6 7.4 34 Zinc/Chelant 9/Phosphonate 1 2.2/5/8.8 1.0 0.8 - .;
~ Chelant 1 = N, N'-di(-2 hydroxybenzyl -~ trimethylenediamine-N,N'-diacetic acid Chelant 2 = N,N' Ethylene-bis- [2~2-hydroxy-4 methyl-phenyl) - glycine]
Chelant 3 = Ethylenediamine N, N'bis-[2 hydroxyl phenyl ~- acetic acid]
Chelant 4 = Ethylenediamine tetraacetic acid.
Chelant S s NIN-di (2 hydroxy ethyl) glycine.
- 25 helant 6 - N-Hydroxyethyl,N,N' Ethylenediamine triacetic acid.
Chelant 7 - 2-hydroxyethyl iminodiacetic acid.
Chelant 8 - Diethylene triamine penta acetic acid.
helant 9 ~ N,N-di~2 hydroxy -5-sulphonic acid benzyl) 30 glyclne ~--Pho~phonate 1 = 2-Phosphonobutane 1,2,4 tricarboxylic acid.
Phosphonate 2 - Rydroxy ethylidene di-phosphonic acid.
Phosphonate 3 ~ ~ydroxy phosphonoacetic acid. ~
','';~,. ':
,~
', . ~
~33~ 3~ :
Phosphino l = Phosphino polyacrylic acid, M.Wt. approx 500 (sold commercially as "Belclene S00" ~;
Ciba Geigy).
Polymer l = Copolymer of methacrylic acid/acrylamide, mole ratio 1:3, M.Wt. 35,000.
Polymer 2 = Polyacrylic acid, M.Wt.1000.
Polymer 3 = Polyacrylic acid, M.Wt.4500.
Examples 15 - 34 indicate:
i) The excellent corrosion inhibiting properties of the ~-zinc/chelant/phosphonate combinations are maintained at the higher test temperature; this is less marked with Chelant 8 which does not contain a hydroxy;group -~
(Example 32). The excellent corrosion inhibition is -~
also maintained when the phosphonate is replaced by the phosphino-polycarboxylic acid in the 3 component combination.
ii) The presence of Polymer l, (Example 20), enhances the corrosion protection conferred by the 4 component blend over that given by the cvrresponding 3 ; 20 component blend, (Example l9), without polymer.
iii) The improvement brought about by the presen~e of the chelant with the zinc/polyacrylic acid combination. -~
Examples 35 to 43 These Examples illustrate the effect of longer term tests. i~
25j~These were~carried out on a laboratory scale simulated ~;~ open, evaporative, recirculating cooling water system inoorporating mild ~teel heat exchanger together with feed a~nd bleed facilities which enable the system to run at a given concentration factor throughout the 14 day test.
The est conditions were as follows~
,, ,~
~: ' ~1332~3~
System Water : 160ppm C31cium hardness 50ppm Magnesium hardness 200ppm 'M' Alkalinity Water Temperature (Pond) : 50C
The present invention relates to the treatment of aqueous systems and, more particularly, to reducing or eliminating corrosion in asueous systems.
Many different types of material have been employed to prevent or inhibit corrosion in aqueous systems. These include inorganic salts such as nitrites and chromates, inorganic mono and polyphosphates, certain water soluble polymers including naturally occurring materials such as lignins and starches as well as synthetic materials such as polyacrylates, as well as organic phosphonates. In addition, it is well known to use zinc salts for this -~
purpose. Indeed, it is known to use zinc salts in combination with organic type corrosion inhibitors, principally organic phosphonates and polyacrylates.
: ~ :
The u~e of zinc salts enables one to passivate corrosion of the metal in contact with the system. It is generally ~;,,;
believed that localised high concentrations of hydroxide ions arise at sites of corrosion on the metal surface because, due to the galvanic cell effect, oxygen present -~
in the water is reduced to hydroxide ions at the ca hodic sites. These hydroxide ions then react with zinc ions of - -~ the zinc salt to give zinc hydroxide which in turn yields - a protective film on the metal surface.
While this pas6ivation system works reasonably sati8factorily in some aqueous media it is known that the use of zinc salt~, with or wlthout the organic type corrosion inhibitor, is ineffective when the pH of the system is high, for example at pH from 8.2 to 9Ø Such a -~
pH can be pre~ent when the water is hard, or is otherwise ~ \
- ~ 332:~ 3~
alkaline ie of low hardness and high alkalinity as can be the case with base exchanged water. Under such circumstances, the zinc hydroxide precipitates prematurely in the system water and therefore does not form a protective film over the metal. Thus in such systems the zinc actually becomes a foulant of the system. Similar problems arise when th~ temperature of the aqueous system i5 raised, for example to at least 40C as can occur when the aqueous system is used as cooling water which comes into contact with hot metal surfaces.
It has now surprisingly been found, according to the present invention, that ~ore effective corrosion inhibition can be obtained when a zinc salt is used together with a class of phosphonate or similar material and, in addition, a chelant. It has been found that this combination is capable of being effective under a combination of severe pH and temperature conditions. It is considerably more effective than existing zinc/organic products on pre-corroded mild steel surfaces since the combination is capable of stifling existing corrosion as ;~ well as enabling much faster passivation of the rusty surface to be brought about. Thus the combination, as well as inhibiting corrosion, also acts as an on line cleaning agent by removing old rust.
, According to the present invention there is provided a method of treating an aqueous system which comprises adding thereto a zinc salt, a chelant and either a product containing ~t least one phosphorus-containing acid group and at least one carboxylic acid group or an acrylic, vinyl or allyl carboxylic acid polymer.
Generally, any water soluble zinc salt can be used in the present invention. Typical salts which can be used ..... .
include zinc sulphate, zinc chloride, zinc nitrate and zinc acetate, zinc sulphate monohydrate and zinc chloride being particularly preferred. -The third component used in the present invention will, in S general, be a phosphonate. Preferably, the materials used contain at least two acid groups, one of which is a phoæphonate group and the other is a carboxylic acid group, at least the two said acid groups being attached to ~
carbon atoms. , 10 Preferred phosphonates include hydroxy phosphonoacetic ~,~
;~ acid and 2-phosphono butane-1,2,4-tricarboxylic acid, the ~ h latter being particularly preferred. Thus these preferred ; ~ phosphonates possess the general formula O R
~ 0 ) 2P f COOH
~ H2 - COOH
, " . ~ , .,,:
~ 15 wherein R is hydrogen, alkyl, alkenyl or alkynyl having up .~ to 4 carbon atoms; phenyl; cycloalkyl having 3 to 6 carbon ~`
atoms; benzyl; phenethyl or ~ -R' ~"
CH ~ R
wherein R' is hydrogen, alkyl having 1 to 4 carbon atoms or carboxyl, Ra is hydrogen or methyl and R''' is carboxyl or phosphonate. ~
, , ,:
'.:., ''' :'`' .
.
-:
~ 3321:~
It is also possible to employ as the third component in the method a polymeric material and, in particular, carboxylic acid polymers which contain a chain phosphorus atom which forms part of an acid group. Thus these polymeric materials are preferably phosphino polycarboxylic acids, typically those having the formula Hf -- CH~p~/H2 -- I H~ :~
~ HOOC J ~H ~ COOH
where N + M = 4 to 20 The molecular weight of such polymers is relatively low, generally below 5,000, the preferred molecular weight being from 250 to 750, especially about 500. A
particularly suitable polymer is that sold as ~Belclene 500" by Ciba-Geigy.
~' It has also been found that a synergistic effect, although most pronounced when the phosphorus containing materials ` are used, can also be obtained when a polycarboxylic acid - ~; is uæed, typically one having a molecular weight from 1,000 to 5,000. Such polymers may be derived from acrylic, vinyl or allyl carboxylic monomers, typically acrylic, methacrylic, maleic, fumaric, itaconic, crotonic or ~innamic acid alone or with a suitable comonomer. Such comonomers include acrylamide, (meth)acrylate esters or hydroxy esters e.g. hydroxypropyl esters, vinyl pyrrolidone, vinyl acetate, acrylonitrine, ~inyl methyl ether, 2-acrylamido-2-methyl-propane sulphonic acid, vinyl or allyl ~ulphonic acid and styrene sulphonic acid as well as cationic monomers such as diallyl dimethyl ammonium chloride, dimethylamino ethylacrylate or methacrylate, optionally quaternised with, for example, dimethyl J ~ :
,''''~`~.
``` ' ~33~13g ' s~lphate or methyl chloride.
i The chelants which can be used in the method of the present invention are generally compounds with a nitrogen ligand which are effective chelants for iron Usually, these chelants will also possess a carboxylic acid group.
A preferred group of chelants possesses the formula ;
R3 - ~ - CH - R2 where Rl is hydrogen, hydroxyethyl or carboxymethyl, preferably carboxymethyl, R2 ~s hydrogen, hydroxyphenyl, ~-~
preferably ortho-hydroxyphenyl, which is optionally methyl or sulphonic acid substituted, or carboxyl, R4 is hydrogen or carboxyl, ~
Rl R4 -R is - X - N - CH - R , -CH2CH20H, R1~4 -CH2C6H~(OH)(S03H) or -CH2C6H2(OH)~CH3)CH2~-N-R
where R , R2 and R4 are as defined above and X is -(CH2)2- or - ~CH2)3 -~ The phenyl groups may be substituted, if desired, preferably by one or more halogen atoms. `~
: ~ ' , ~-`,' If the chelant is to be used in aqueous systems which 20 possess a high pH and a relatively high temperature it is ~
preferred that at least one of Rl, R2 and R3 contains a -~`
`~ hydroxyl group. Thus the most preferred chelants possess a nitrogen ligand, a carboxylic acid group and a hydroxyl ~ group~
; ~ 25l Preferred chelants for use in t~e present invention include N~N'-di(-2-hydroxybenzyl-)trimethylened1amine-N, N'-diacetic acid, N,N'ethylene-bis-[2-(2-hydroxy-4-methyl-phenyl)-glycine], ethylenediamine N, N'-bis-[2-hydroxyphenylacetic acid] and N, 30 N-di(2-hydroxy-5-sulphonic acid benzyl~glycine which is A ;~
~;
~ 3~2i~8 especially preferred not only on account of its effectiveness but also on account of its excellent solubility properties which faciliate the formulation of compositions, as well as N,N-di(2-hydroxyethyl) glycine, S N-hydroxyethyl N,N',N'-ethylenediamine triacetic acid and 2-hydroxyethyl iminodiacetic acid. Ethylenediamine tetraacetic acid and diethylene triamine pentaacetic acid can also be mentioned although they are less preferred since they do not contain a hydroxyl group (other than as part of the carboxylic acid groups).
In general, from 1 to 10 parts by weight of chelant and from 4 to 6 parts by weight of the phosphorus containing compound are employed to 1 part of the zinc salt. While in certain circumstances it may be desirable to add the individual components separately, in other situations it will be convenient to add the components together in the form of a composition. Accordingly, the present invention also provides a composition suitable for addition to an aqueous system which comprises a water ~-soluble zinc salt, a product containing at least one phosphorus containing acid group and at least one carboxylic acid group or an acrylic, vinyl or allyl carboxylic acid polymer, and a chelant. In such a situation, it may be desirable to add further quantities of chelant as required~ Typically, the composition will be an aqueous formulation containing, generally, 1% to 2%
by weight Qf zinc salt (as zinc), 4~ to 10% by weight of the phosphorus containing material or polymer and 1~ to ' 25~ by weight, especially about 5% by weight, of the ;~
; 30 chelant.
A further surprising feature of the present invention is that the presence of the combination of chelant and phosphorus conta~ning compound and/or acrylic vinyl or ~332~
- 7 - ~-allyl carboxylic acid polymer enables one to reduce the amount of zinc salt. It is usual in the art to employ amounts of the order of 2 to 5ppm zinc. However, with ever increasing restrictions on concentrations of zinc in discharges there is a constant demand to reduce the amounts of zinc used. It has been found that by using the additional ingredients it is possible to reduce the amount of zinc to, say, about lppm for comparable effectiveness.
In such circumstances it is preferred to employ about 4ppm of the phosphorus compound and about 2.5 to 5ppm of chelant. If, on the other hand, one usès 2.5ppm of zinc then it is preferred to use about lOppm of phosphorus compound and about 5ppm of chelant.
.
It is also possible to use the combination of the present invention together with other ingredients including phosphates, biocides, yellow metal corrosion inhibitors such as benzotriazole and tolyltriazole as well as other ;
;~ polymers which act as dispersants such as polyacrylic 1~ acid, polymaleic acid and copolymers of maleic acid with l 20 styrene sulphonic acid. In particular, it has been found ¦~ that the use of certain disper~ants, especially a ~ ;~
¦~ copolymer of methacrylic acid and acrylamide is particularly advantageous, especially one in which the mole ratio is about 1:3, and further enhances the corrosion protection given by the three component system.
In general the molecular weight of the homopolymers will be 1,000 to lO,000 while that of the copolymers will be l,000 to 50,000.
The use of a phosphate is particularly noteworthy since zinc phosphate i9 effective in low water hardness systems because the zinc phosphate itself gives protection. By using the chelant and phosphorus containing compound as -~
well it is possible, as previously discussed, to use ., ~ ~ 33~ 3~
, significantly lower quantities of zinc.
The following Examples further illustrate the present invention.
Examples 1 to 34 In these Examples tests were carried out on a laboratory scale recirculating rig consisting of a plastic vessel holding 8 litres of water and connected by tubing to a ¦~; circulating pump the water passing from the pump through a glass rack holding the metal test coupons ('line') and returning to the plastic vessel. Any evaporation was made ~ up by the addition of de-ionised water. Metal test I coupons were also suspended in the plastic vessel ('Pond'). ~he corrosion rate was calculated from the -weight of metal lost during test. The water temperature was maintained by means of a heater/thermostat arrangement. The conditions of the test were as follows:
System Water : 150ppm Ca hardness/150ppm 'M' Alkalinity Water pH : 8.8 ~; 20 ~Water Temperature : 54 C or 40C ~as stated) Flow Rate : Line : 2 ft/sec `~
Pond : 0.2 ft/sec Duration of Test : 3 days Tnitial Passivation : 1 day at 3 times normal ; 25~ maintenance dose.
Examples No. 1 - 14 were carried out at 40C.
'"';''.:`
. ''' '' '.~
133~1~8 Example Additive Dose, ppm Corrosion of -No. Mild Steel in mils per year (mpy) :
Line Pond No addition :~ 2 Zinc/Chelant 1/~ - 2.2/5/--- 5.7 12.9 3 Zinc/Chelant l/Phosphonate 1 2.2/5/8.8 1.0 0.9 4 zinc,~ /Phosphonate 1 2.2/-/8.8 7.8 3.3 ~; 10 5 Zinc/Chelant 2/------- 2.2/5/---1.1 8.8 ~: 6 Zinc/Chelant 2/Phosphonate 1 2.2/5/8.8 0.2 0.3 --. ~: 7 Zinc/Chelant 3/~ -- 2.2/5/--- 1.5 2.4 . -:
8 Zinc/Chelant 3/Phosphonate 1 2.2/5/8.8 1.1 1.6 9 Zinc/Chelant 4/------- 2.2/5/---9.0 . 7.3 -~.~
Zinc/Chelant 4/Phosphonate 1 2.2/5/8.8 0.3 0.7 .` ;
11 Zinc/Chelant 5/------- 2.2/5/---10.7 12.9 12 Zinc/Chelant 5/Phosphonate 1 2.2/5/8.8 1.9 8.6 :~
;13 Zinc/Chelant 2/Phosphonate 2 2.2/5/8.8 4.5 4.8 ;:
14 Zinc/Chelant 9/Phosphonate 1 2.2/5/8.8 0.2 0.2 .
20~ ~;Examples 1 - 14 illustrate:
he blend of z`i~n~/chelant/phosphonate is superior to zinc/phosphonate or zinc/chelant.
The~prefer;red ~chelants are Chelants 1, 2,3 and 9.
$ii~ Phosphonate l :gives significantly better results ~-25 :~ than~comparative Phosphonate 2.
Examples l5 - 34 were carried out at 54C.
15 Zinc/Chelant 2/Phosphino 1 2.2/5/8.82.9 5.3 16~::Z:inc,~Chelant 2/Phosphino 1 2.5/5/10.0 1.2 3.1 `; 17 ~Zinc/~ Phosphino 1 2.2/-/8.810.5 11.7 ~:
: 30 18 Zinc/Chelant 2/Phosphonate 1 2.2/5/5 0.5 1.6 ~ `~
19 Zinc/Chelant 2/Phosphonate 1 2.2/5/8.8 0.5 1.4 .::
., , :',; .
' " ~
~',' 13~2~3 Zinc/Chelant 2/Phosphonate 1/
Polymer 1 2.2/5/8.8/2.5 0.4 0.9 21 Zinc/Chelant 2/Phosphonate 3 2.2/5/8.8 0.4 0.5 22 Zinc/Chelant l/Phosphonate 1 2.2/5/8.8 1.2 5.0 23 Zinc/Chelant 4/Phosphonate 1 2.2/5/8.8 2.3 5.6 24 Zinc/Chelant 3/Phosphonate 1 2.2/5/8.8 1.6 2.4 Zinc/Chelant 3/Phosphonate 1 1/5/4.4 2.1 5.2 26 Zinc/Chelant 2/Polymer 22.2/5/10 5.2 9.1 27 Zinc/~ /Polymer 2 2.2/-/10 21.4 21.3 28 Zinc/Chelant 2/Polymer 32.2/5/107.2 9.7 29 Zinc/-~ /Polymer 3 2.2/-/10 17.7 32.2 Zinc/Chelant 6/Phosphonate 1 2.2/5/8.8 3.1 3.4 31 Zinc/Chelant 7/Phosphonate 1 2.2/5/8.8 3.2 2.1 32 Zinc/Chelant 8/Phosphonate 1 2.2/5/8.8 3.6 6.8 33 Zinc/------ /Phosphonate 12.2/-/8.8 9.6 7.4 34 Zinc/Chelant 9/Phosphonate 1 2.2/5/8.8 1.0 0.8 - .;
~ Chelant 1 = N, N'-di(-2 hydroxybenzyl -~ trimethylenediamine-N,N'-diacetic acid Chelant 2 = N,N' Ethylene-bis- [2~2-hydroxy-4 methyl-phenyl) - glycine]
Chelant 3 = Ethylenediamine N, N'bis-[2 hydroxyl phenyl ~- acetic acid]
Chelant 4 = Ethylenediamine tetraacetic acid.
Chelant S s NIN-di (2 hydroxy ethyl) glycine.
- 25 helant 6 - N-Hydroxyethyl,N,N' Ethylenediamine triacetic acid.
Chelant 7 - 2-hydroxyethyl iminodiacetic acid.
Chelant 8 - Diethylene triamine penta acetic acid.
helant 9 ~ N,N-di~2 hydroxy -5-sulphonic acid benzyl) 30 glyclne ~--Pho~phonate 1 = 2-Phosphonobutane 1,2,4 tricarboxylic acid.
Phosphonate 2 - Rydroxy ethylidene di-phosphonic acid.
Phosphonate 3 ~ ~ydroxy phosphonoacetic acid. ~
','';~,. ':
,~
', . ~
~33~ 3~ :
Phosphino l = Phosphino polyacrylic acid, M.Wt. approx 500 (sold commercially as "Belclene S00" ~;
Ciba Geigy).
Polymer l = Copolymer of methacrylic acid/acrylamide, mole ratio 1:3, M.Wt. 35,000.
Polymer 2 = Polyacrylic acid, M.Wt.1000.
Polymer 3 = Polyacrylic acid, M.Wt.4500.
Examples 15 - 34 indicate:
i) The excellent corrosion inhibiting properties of the ~-zinc/chelant/phosphonate combinations are maintained at the higher test temperature; this is less marked with Chelant 8 which does not contain a hydroxy;group -~
(Example 32). The excellent corrosion inhibition is -~
also maintained when the phosphonate is replaced by the phosphino-polycarboxylic acid in the 3 component combination.
ii) The presence of Polymer l, (Example 20), enhances the corrosion protection conferred by the 4 component blend over that given by the cvrresponding 3 ; 20 component blend, (Example l9), without polymer.
iii) The improvement brought about by the presen~e of the chelant with the zinc/polyacrylic acid combination. -~
Examples 35 to 43 These Examples illustrate the effect of longer term tests. i~
25j~These were~carried out on a laboratory scale simulated ~;~ open, evaporative, recirculating cooling water system inoorporating mild ~teel heat exchanger together with feed a~nd bleed facilities which enable the system to run at a given concentration factor throughout the 14 day test.
The est conditions were as follows~
,, ,~
~: ' ~1332~3~
System Water : 160ppm C31cium hardness 50ppm Magnesium hardness 200ppm 'M' Alkalinity Water Temperature (Pond) : 50C
5 pH : 8.8 Flow Rate through heat exchanger : 0.3 ft/sec ;~-Plow Rate through coupon chamber : 1.5 ftJsec 10 Heat flux on exchanger 75 kj/ -2/
Duration of test : 14 days ~ ;
Initial passivation : 3 x normal maintenance dose, allowed to decay from start of test.
15 Example ~ Additive Dose,ppm Corrosion Rate ~ No. mpy ~-`~ Heat Coupon Exchanger in line Zinc/Chelant 2/Phosphonate 1 2.2/2.5/8.8 7.8 1.0 ``~
36 Zinc/Chelant 2/Phosphonate 1 2.2/5/8.8 3.5 0.5 ;
37~ Zinc/Chelant 2/Phosphonate 1 2.2/7.5/8.8 5.6 1.1 38 Zinc/Chelant 2/Phosphonate 1 2.2/10/8.8 6.9 1.2 ;~
39~ zinc/Chelant 4/Phosphonate 1 2.2/5/8.8 63.6 38.7 4Q Zinc/~ /Phosphonate 1 2.2/--/8.8 9.5 1.0 25 ~ 41 Zinc/~helant 5/Pho~phonate 1 2.2/5/8.8 4.6 1.8 42 Zin~/0-phosphate/Chelant 2/ 1.1/1.5/5/5 2.6 1.0 Phosphonate 1 `,- ,43 Zinc/0-phosphate/ 2.2/3.0/-/5 4.2 ~ 6.~8 Phosphonate 1 30 0-phosphate ~i disodium ortho-phosphate --It was noticed that when Chelant 2 was in use (Examples 35 to 38), the corrosion which initiated on the heat exchanger was rapidly st~1ed whereas in Example 40 ~ . ~
' ~ , ' ;, . ~`, ~3~213~
corrosion spread throughout the test. Chelant 4 was largely ineffective; in fact, the results indicate aggresSion. This shows that this chelant is unsuitable where there is a heat exchanger giving a high surface temperature.
Example 42 in relation to Example 43 shows the effect of using Chelant 2 in enabling one to reduce the concentration of zinc/phosphate.
, .: :
, `::
,, .
. ~ .
::
.~
, :
Duration of test : 14 days ~ ;
Initial passivation : 3 x normal maintenance dose, allowed to decay from start of test.
15 Example ~ Additive Dose,ppm Corrosion Rate ~ No. mpy ~-`~ Heat Coupon Exchanger in line Zinc/Chelant 2/Phosphonate 1 2.2/2.5/8.8 7.8 1.0 ``~
36 Zinc/Chelant 2/Phosphonate 1 2.2/5/8.8 3.5 0.5 ;
37~ Zinc/Chelant 2/Phosphonate 1 2.2/7.5/8.8 5.6 1.1 38 Zinc/Chelant 2/Phosphonate 1 2.2/10/8.8 6.9 1.2 ;~
39~ zinc/Chelant 4/Phosphonate 1 2.2/5/8.8 63.6 38.7 4Q Zinc/~ /Phosphonate 1 2.2/--/8.8 9.5 1.0 25 ~ 41 Zinc/~helant 5/Pho~phonate 1 2.2/5/8.8 4.6 1.8 42 Zin~/0-phosphate/Chelant 2/ 1.1/1.5/5/5 2.6 1.0 Phosphonate 1 `,- ,43 Zinc/0-phosphate/ 2.2/3.0/-/5 4.2 ~ 6.~8 Phosphonate 1 30 0-phosphate ~i disodium ortho-phosphate --It was noticed that when Chelant 2 was in use (Examples 35 to 38), the corrosion which initiated on the heat exchanger was rapidly st~1ed whereas in Example 40 ~ . ~
' ~ , ' ;, . ~`, ~3~213~
corrosion spread throughout the test. Chelant 4 was largely ineffective; in fact, the results indicate aggresSion. This shows that this chelant is unsuitable where there is a heat exchanger giving a high surface temperature.
Example 42 in relation to Example 43 shows the effect of using Chelant 2 in enabling one to reduce the concentration of zinc/phosphate.
, .: :
, `::
,, .
. ~ .
::
.~
, :
Claims (60)
1. A method of treating an aqueous system which comprises adding thereto a water soluble zinc salt, a chelant which possesses the formula:
wherein R1 is hydrogen, hydroxyethyl or carboxymethyl, R2 is hydrogen, hydroxyphenyl, which is optionally methyl or sulfonic acid substituted, or carboxyl, R4 is hydrogen or carboxyl, R3 is , -CH2CH2OH, - CH2C6H3(OH) (SO3H) or wherein R1, R2 and R4 are as above defined and X is -(CH2)2- or -(CH2)3-, the phenyl groups being optionally further substituted by one or more halogen atoms with the proviso that at least one of R2 and R3 contains a hydroxyphenyl group and either a product containing at least one carboxylic acid group or an acrylic, vinyl or allyl carboxylic acid polymer.
- 14(a) -
wherein R1 is hydrogen, hydroxyethyl or carboxymethyl, R2 is hydrogen, hydroxyphenyl, which is optionally methyl or sulfonic acid substituted, or carboxyl, R4 is hydrogen or carboxyl, R3 is , -CH2CH2OH, - CH2C6H3(OH) (SO3H) or wherein R1, R2 and R4 are as above defined and X is -(CH2)2- or -(CH2)3-, the phenyl groups being optionally further substituted by one or more halogen atoms with the proviso that at least one of R2 and R3 contains a hydroxyphenyl group and either a product containing at least one carboxylic acid group or an acrylic, vinyl or allyl carboxylic acid polymer.
- 14(a) -
2. A method according to Claim 1 in which the chelant possesses the formula where R1 is hydrogen, hydroxyethyl or carboxymethyl, R2 is hydrogen, hydroxyphenyl, which is optionally methyl or sulphonic acid substituted, or carboxyl, R4 is hydrogen or carboxyl, R3 is , -CH2CH2OH, -CH2C6H3(OH)(SO3H) or wherein R1, R2 and R4 are as defined above and X is -(CH2)2- or -(CH2)3-; the phenyl groups being otionally further substituted by one or more halogen atoms.
3. A method according to Claim 2 in which 1 to 10 parts by weight of chelant are added per part by weight of zinc salt.
4. A method according to Claim 3 in which 4 to 6 parts by weight of the phosphorus-containing compound are added per part by weight of the zinc salt.
5. A method according to Claim 2, 3 or 4 in which the zinc salt is zinc sulphate, zinc chloride, zinc nitrate or zinc acetate.
6. A method according to Claim 2, 3 or 4 in which the phosphonate has the general formula wherein R is hydrogen, alkyl, alkenyl or alkynyl having up to 4 carbon atoms; phenyl; cycloalkyl having 3 to 6 carbon atoms; benzyl; phenethyl or wherein R' is hydrogen, alkyl having 1 to 4 carbon atoms or carboxyl, R" is hydrogen or methyl and R''' is carboxyl or phosphonate.
7. A method according to Claim 2, 3 or 4 in which the phosphonate is hydroxy-phosphonoacetic acid or 2-phosphonobutane-1,2,4-tricarboxylic acid.
8. A method according to Claim 2, 3 or 4 in which the product containing at least one phosphorus-containing acid group and at least one carboxylic acid group is a phosphino polycarboxylic acid having the formula where N + M = 4 to 20.
9. A method according to Claim 1, 2 or 3 in which the polymer is a copolymer of acrylic, methacrylic, maleic, fumaric, itaconic, crotonic or cinnamic acid with acrylamide, an acrylate or methacrylate ester or hydroxy ester, vinyl pyrrolidone, vinyl acetate, acrylonitrile, vinyl methyl ether, 2-acrylamido-2-methyl-propane sulphonic acid, vinyl, allyl or styrene sulphonic acid, or diallyldimethyl ammonium chloride or dimethylamino ethyl acrylate or methacrylate, optionally quaternised with dimethyl sulphate or methyl chloride.
10. A method according to Claim 1, 2 or 3 in which the polymer is a polymer of acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid or crotonic acid, having a molecular weight from 1000 to 5000.
11. A method according to Claim 2, 3 or 4 in which the zinc salt is added in an amount to provide up to 5 ppm zinc.
12. A method according to Claim 2, 3 or 4 in which the zinc salt is added to provide up to 2 ppm zinc.
13. A method according to Claim 2, 3 or 4 in which the system water attains a temperature of at least 40°C.
14. A method according to Claim 2, 3 or 4 in which the system water attains a pH of 8.2.
15. A method according to Claim 1 in which the chelant is N,N'-di(2-hydroxyethyl) glycine.
16. A method according to Claim 1 or Claim 15 in which the zinc salt is zinc sulphate, zinc chloride, zinc nitrate or zinc acetate.
17. A method according to Claim 1 in which the chelant is N,N'-di(2-hydroxybenzyl)-trimethylenediamine-N,N'-diacetic acid, N,N'-ethylenebis-[2-(2-hydroxy-4-methyl-phenyl)-glycine], ethylenediamine N,N'-bis-[2-hydroxyphenylacetic acid] or N,N-di(2-hydroxy-5-sulphonic acid benzyl) glycine.
18. A method according to Claim 17 in which 1 to 10 parts by weight of chelant are added per part by weight of zinc salt.
19. A method according to Claim 18 in which the zinc salt is zinc chloride, zinc nitrate or zinc acetate.
20. A method according to Claim 17, 18 or 19 in which 4 to 6 parts by weight of the phosphorus-containing compound are added per part by weight of the zinc salt.
21. A method according to Claim 15, 17 or 18 in which the phosphonate has the general formula wherein R is hydrogen, alkyl, alkenyl or alkynyl having up to 4 carbon atoms; phenyl; cycloalkyl having 3 to 6 carbon atoms; benzyl; phenethyl or wherein R' is hydrogen, alkyl having 1 to 4 carbon atoms or carboxyl, R" is hydrogen or methyl and R''' is carboxyl or phosphonate.
22 A method according to Claim 15, 17 or 18 in which the phosphonate is hydroxy-phosphonoacetic acid or 2-phosphonobutane-1,2,4-tricarboxylic acid.
23. A method according to Claim 15, 17 or 18 in which the product containing at least one phosphorus-containing acid group and at least one carboxylic acid group is a phosphino polycarboxylic acid having the formula where N + M = 4 to 20.
24. A method according to Claim 15, 17 or 18 in which the polymer is a copolymer of acrylic, methacrylic, maleic, fumaric, itaconic, crotonic or cinnamic acid with acrylamide, an acrylate or methacrylate ester or hydroxy ester, vinyl pyrrolidone, vinyl acetate, acrylonitrile, vinyl methyl ether, 2-acrylamido-2-methyl-propane sulphonic acid, vinyl, allyl or styrene sulphonic acid, or diallyldimethyl ammonium chloxide or dimethylamino ethyl acrylate or methacrylate, optionally quaternised with dimethyl sulphate or methyl chloride.
25. A method according to Claim 15, 17 or 18 in which the polymer is a polymer of acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid or crotonic acid, having a molecular weight from 1000 to 5000.
26. A method according to Claim 15, 17 or 18 in which the zinc salt is added in an amount to provide up to 5 ppm zinc.
27. A method according to Claim 15, 17 or 18 in which the zinc salt is added to provide up to 2 ppm zinc.
28. A method according to Claim 15, 17 or 18 in which the system water attains a temperature of at least 40°C.
29. A method according to Claim 15, 17 or 18 in which the system water attains a pH of 8.2.
30. A method according to Claim 1, 3 or 18 in which the product containing at least one phosphorus-containing acid group is a phosphonate containing at least two acid groups one of which is a phosphonate and the other is a carboxylic acid group, at least the two said acid groups being attached to carbon atoms.
31. A composition suitable for addition to an aqueous system which comprises a water-soluble zinc salt, a chelant, and a product containing at least one phosphorus-containing acid group and at least one carboxylic acid group or an acrylic, vinyl or allyl carboxylic acid polymer.
32. A composition according to Claim 31 in which the chelant possesses the formula wherein R1 is hydrogen, hydroxyethyl or carboxymethyl, R2 is hydrogen, hydroxyphenyl, which is optionally methyl or sulphonic acid substituted, or carboxyl, R4 is hydrogen or carboxyl, R3 is , -CH2CH2OH, -CH2C6H3(OH)(SO3H) or wherein R1, R2 and R3 are as defined above and X is -(CH2)2- or -(CH2)3-; the phenyl groups being otionally further substituted by one or more halogen atoms.
33. A composition according to Claim 32 which contains 1 to 10 parts by weight of chelant per part by weight of zinc salt.
34. A composition according to Claim 33 which contains 4 to 6 parts by weight of the phosphorus-containing compound per part by weight of the zinc salt.
35. A composition according to Claim 32, 33 or 34 in which the zinc salt is zinc sulphate, zinc chloride, zinc nitrate or zinc acetate.
36. A composition according to Claim 32, 33 or 34 in which the phosphonate has the general formula wherein R is hydrogen, alkyl, alkenyl or alkynyl having up to 4 carbon atoms; phenyl; cycloalkyl having 3 to 6 carbon atoms; benzyl; phenethyl or wherein R' is hydrogen, alkyl having 1 to 4 carbon atoms or carboxyl, R" is hydrogen or methyl and R''' is carboxyl or phosphonate.
37. A composition according to Claim 32, 33 or 34 in which the phosphonate is hydroxy-phosphonoacetic acid or 2-phosphonobutane-1,2,4-tricarboxylic acid.
38. A composition according to Claim 32, 33 or 34 in which the product containing at least one phosphorus-containing acid group and at least one carboxylic acid group is a phosphino polycarboxylic acid having the formula where N + M = 4 to 20.
39. A composition according to Claim 31, 32 or 33 in which the polymer is a copolymer of acrylic, methacrylic, maleic, fumaric, itaconic, crotonic or cinnamic acid with acrylamide, an acrylate or methacrylate ester or hydroxy ester, vinyl pyrrolidone, vinyl acetate, acrylonitrile, vinyl methyl ether, 2-acrylamido-2-methyl-propane sulphonic acid, vinyl, allyl or styrene sulphonic acid, or diallyldimethyl ammonium chloride or dimethylamino ethyl acrylate or methacrylate, optionally quaternised with dimethyl sulphate or methyl chloride.
40. A composition according to Claim 31, 32 or 33 in which the polymer is a polymer of acrylic acid, metha-crylic acid, maleic acid, fumaric acid, itaconic acid or crotonic acid, having a molecular weight from 1000 to 5000.
41. A composition according to Claim 31, 32 or 33 which is aqueous.
42. A composition according to Claim 31, 32 or 33 which is aqueous and contains from 1 to 2 percent by weight of zinc salt (as zinc), from 4 to 10 percent by weight of the phosphorus and carboxylic acid group-containing material or polymer and from 1 to 25 percent by weight of the chelant.
43. A composition according to Claim 31, 32 or 33 which further comprises a phosphate, biocide, yellow metal corrosion inhibitor or dispersant.
44. A composition according to Claim 31, 32 or 33 which further comprises a dispersant which is a copolymer of methacrylic acid and acrylamide.
45. A composition according to Claim 31 in which the chelant is N,N'-di(2-hydroxyethyl) glycine.
46. A composition according to Claim 45 which contains 1 to 10 percent by weight of chelant per part by weight of zinc salt.
47. A composition according to Claim 31 in which the chelant is N,N'-di(2-hydroxybenzyl)-trimethylenediamine-N,N'-diacetic acid, N,N'-ethylenebis-[2-(2-hydroxy-4-methyl-phenyl)-glycine], ethylenediamine N,N'-bis-[2-hydroxyphenylacetic acid] or N,N-di(2-hydroxy-5-sulphonic acid benzyl) glycine.
48. A composition according to Claim 47 which contains 1 to 10 parts by weight of chelant per part by weight of zinc salt.
49. A composition according to Claim 1, 46 or 48 in which the zinc salt is zinc chloride, zinc nitrate or zinc acetate.
50. A composition according to Claim 46, 47 or 48 which contains 4 to 6 parts by weight of the phosphorus-containing compound per part by weight of the zinc salt.
51. A composition according to Claim 45, 47 or 48 in which the phosphonate has the general formula wherein R is hydrogen, alkyl, alkenyl or alkynyl having up to 4 carbon atoms; phenyl; cycloalkyl having 3 to 6 carbon atoms; benzyl; phenethyl or wherein R' is hydrogen, alkyl having 1 to 4 carbon atoms or carboxyl, R" is hydrogen or methyl and R''' is carboxyl or phosphonate.
52. A composition according to Claim 45, 47 or 48 in which the phosphonate is hydroxy-phosphonoacetic acid or 2-phosphonobutane-1,2,4-tricarboxylic acid.
53. A composition according to Claim 45, 47 or 48 in which the product containing at least one phosphorus-containing acid group and at least one carboxylic acid group is a phosphino polycarboxylic acid having the formula where N + M = 4 to 20.
54. A composition according to Claim 45, 47 or 48 in which the polymer is a copolymer of acrylic, methacrylic, maleic, fumaric, itaconic, crotonic or cinnamic acid with acrylamide, an acrylate or methacrylate ester or hydroxy ester, vinyl pyrrolidone, vinyl acetate, acrylonitrile, vinyl methyl ether, 2-acrylamido-2 methyl-propane sulphonic acid, vinyl, allyl or styrene sulphonic acid, or diallyldimethyl ammonium chloride or dimethylamino ethyl acrylate or methacrylate, optionally quaternised with dimethyl sulphate or methyl chloride.
55. A composition according to Claim 45, 47 or 48 in which the polymer is a polymer of acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid or crotonic acid, having a molecular weight from 1000 to 5000.
56. A composition according to Claim 45, 47 or 48 which is aqueous.
57. A composition according to Claim 45, 47 or 48 which is aqueous and contains from 1 to 2 percent by weight of zinc salt (as zinc), from 4 to 10 percent by weight of the phosphorus and carboxylic acid group-containing material or polymer and from 1 to 25 percent by weight of the chelant.
58. A composition according to Claim 45, 47 or 48 which further comprises a phosphate, biocide, yellow metal corrosion inhibitor or dispersant.
59. A composition according to Claim 45, 47 or 48 which further comprises a dispersant which is a copolymer of methacrylic acid and acrylamide.
60. A composition according to Claim 33, 46 or 48 in which the product containing at least one phosphorous-containing acid group is a phosphonate containing at least two acid groups one of which is a phosphonate and the other is a carboxylic acid group, at least the two said acid groups being attached to carbon atoms.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08526590A GB2184109A (en) | 1985-10-29 | 1985-10-29 | The treatment of aqueous systems |
| GB8526590 | 1985-10-29 | ||
| GB8623464 | 1986-09-30 | ||
| GB08623464A GB2183624A (en) | 1985-10-29 | 1986-09-30 | Anti-corrosion treatment of aqueous systems |
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| Publication Number | Publication Date |
|---|---|
| CA1332138C true CA1332138C (en) | 1994-09-27 |
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|---|---|---|---|
| CA000521449A Expired - Lifetime CA1332138C (en) | 1985-10-29 | 1986-10-27 | Treatment of aqueous systems |
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| EP (1) | EP0225051B1 (en) |
| AT (1) | ATE72678T1 (en) |
| AU (1) | AU6456486A (en) |
| CA (1) | CA1332138C (en) |
| DE (1) | DE3683928D1 (en) |
| ES (1) | ES2038595T3 (en) |
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| US4717542A (en) * | 1987-01-23 | 1988-01-05 | W. R. Grace & Co. | Inhibiting corrosion of iron base metals |
| NZ226331A (en) * | 1987-10-05 | 1991-08-27 | Calgon Corp | Method of inhibiting corrosion of metallic surfaces in aqueous systems using acrylic polymers and zinc ions; compositions therefor |
| EP0364030A1 (en) * | 1988-10-11 | 1990-04-18 | Calgon Corporation | Synergistic compositions and method for inhibiting carbon steel corrosion in aqueous systems |
| US5171477A (en) * | 1991-05-31 | 1992-12-15 | W. R. Grace & Co.-Conn. | Corrosion inhibition in chelant solutions |
| ES2059273B1 (en) * | 1993-02-09 | 1995-10-01 | Miret Lab | DISPERSING AND INHIBITING COMPOSITIONS OF INCRUSTATION AND / OR CORROSION IN INDUSTRIAL WATER CIRCUITS. |
| US5518629A (en) * | 1993-07-29 | 1996-05-21 | Betz Laboratories, Inc. | Methods for controlling scale formation in acqueous systems |
| WO2000039359A1 (en) * | 1998-12-29 | 2000-07-06 | Calgon Corporation | Corrosion inhibitor compositions and methods to control metal corrosion in brine systems |
| US8513176B2 (en) | 2006-08-02 | 2013-08-20 | Ch2O Incorporated | Disinfecting and mineral deposit eliminating composition and methods |
| CN110158094A (en) * | 2019-07-11 | 2019-08-23 | 北京中天兰清环境科技有限公司 | A kind of formula and preparation method of the without phosphorus carbon steel corrosion inhibitor of composite efficient |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US3669901A (en) * | 1970-10-22 | 1972-06-13 | William Bruce Murray | Corrosion inhibitor composition containing zinc, sulfamate, and phosphate ions |
| US3794603A (en) * | 1972-01-17 | 1974-02-26 | Sherwin Williams Co | Zn++-benzotriazole-h2so4 corrosioninhibitor |
| AU452099B2 (en) * | 1972-08-02 | 1974-08-29 | Applied Chemicals Pty. Limited | Aqueous corrosion inhibiting compositions |
| DE2333353C2 (en) * | 1973-06-30 | 1983-05-19 | Bayer Ag, 5090 Leverkusen | Process for preventing corrosion in water-bearing systems and anti-corrosion agents for carrying out the process |
| US4018701A (en) * | 1975-07-31 | 1977-04-19 | Calgon Corporation | Phosphorous acid and zinc corrosion inhibiting compositions and methods for using same |
| US4042451A (en) * | 1975-08-05 | 1977-08-16 | M&T Chemicals Inc. | Selected stripping of nickel-iron alloys from ferrous substrates |
| DK231879A (en) * | 1978-06-05 | 1979-12-06 | Calgon Corp | PROCEDURE FOR CORROSION INHIBITION AND PRODUCT FOR USE IN THE PERFORMANCE OF THE PROCEDURE |
| GB2118159B (en) * | 1982-04-20 | 1985-09-04 | Dearborn Chemicals Ltd | The treatment of aqueous systems |
-
1986
- 1986-10-27 CA CA000521449A patent/CA1332138C/en not_active Expired - Lifetime
- 1986-10-29 AU AU64564/86A patent/AU6456486A/en not_active Abandoned
- 1986-10-29 DE DE8686308419T patent/DE3683928D1/en not_active Expired - Lifetime
- 1986-10-29 ES ES198686308419T patent/ES2038595T3/en not_active Expired - Lifetime
- 1986-10-29 AT AT86308419T patent/ATE72678T1/en active
- 1986-10-29 EP EP86308419A patent/EP0225051B1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| EP0225051B1 (en) | 1992-02-19 |
| DE3683928D1 (en) | 1992-03-26 |
| ATE72678T1 (en) | 1992-03-15 |
| EP0225051A1 (en) | 1987-06-10 |
| AU6456486A (en) | 1987-04-30 |
| ES2038595T3 (en) | 1993-08-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed | ||
| MKEC | Expiry (correction) |
Effective date: 20121205 |