CA1314904C - Water treatment polymers & methods of use thereof - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

New composition of monomers and polymers and their methods of use are disclosed. The polymers are water soluble and are composed of repeat units formed from an ethylenically unsaturated compound, and repeat units formed from substituted allyloxy alkylenes. The polymers are useful for controlling the formation and deposition of scale imparting compounds in water systems such as cooling, boiler and gas scrubbing systems.

Description

1 3 1 4 9 0 4~

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FIELD OF THE INVENlION ~ : ~
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The present invcntion pertains to a composition and mèthod of utilizing same to control the ~ormation and deposition of scale imparting compounds in water systems such dS cooling, boiler and~ gis scrubbing systems.~

: BAOKGROUND OF TH INVENTION

The problem of scale format10n and attendant::effects have troubled water systems for years. For: instance~ scale tends~:~to accumulate on internai walls of various water sys~ems~ such ~as boiler ~and cooling systems, and t hereby materially ~lessens the operational e~ficiency of the system.

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Deposits in lines, heat exchange equipment, etc., may originate from several causes. For example, precipitation of calcium carbonate, calcium sulfate and calcium phosphate in the water system leads to an accumulation of these scale imparting compounds along or around the metal surfaces which contact the flowing water circulating through the system. In this manner, heat transfer functions of the particular system are severely impeded.

Typically, in cooling water systems, the forma~ion of calcium sulfate, calcium phosphate and calcium carbonate, among others, has proven deleterious to the overal~l efficiency of the cooling water system. Recently, due to the popularity of cooling treatments using high levels of orthophosphate to promote passivation of the metal surfaces in contact with the system water, it has become critically important to control calcium phosphate crystallization so that relatively high~levels of orthophosphate may be maintained in the system to achieve the~ desired~passivation without resu1ting in fouling or impeded heat transfer functions whlch would normally be caused by calcium phosphate deposition~

Although steam generating systems are somewhat different from cooling water systems, they share~a common problem in regard to deposit formation.

As detailed in the Betz Handbook of Industr1al Water Conditioning, Bth Edition, 1980, Betz Laboratories, Inc " Trevose, PA, pages 85-9~, the formation of scale and sludge deposits on boiler heating surfaces is a serious problem encountered~ in ~steam generation. Although current industrial steam producing systems make use of sophisticated external treatments of the boiler ~eedwater, e.g., coagulation~ filtration, softening of water prior :

, ', 1 31 ~qO4 to its feed into the boiler system, these operations are only moderately effective. In all cases, external treatment does not in , itself provide adequate treatment since muds, sludge, silts and hardness-imparting ions escape the treatment, and eventually are introduced into the steam generating system.

In addition to the problems caused by mud, sludge or silts, the industry has also had to contend with boiler scale.
Although ex~ernal treatment is utilized specifically in an attempt to remove calcium and magnesium from ~he feedwater, scale formation due to residual hardness, i.e., calcium and magnesium salts, is always experienced. Accordingly, internal treatment, i.e., treatment of the water to the system, is necessary to prevent, reduce and/or retard formation of the scale imparting compounds and their resultant deposition. The carbonates of magnesium and calcium are not the only problem compounds as regards scale, but also waters having high contents of phosphate, sulfate and silicate ions either occurring naturally or added for other purposes cause problems since calcium and magnesium, and any iron or copper present, react with each and deposit as boiler scale. As is obvious, deposition on the structural parts of a steam generating system causes poorer circulation and lower heat transfer capacityl resulting in an overall loss in efficiency.

SUMMARY OF THE INVENTION

The present invention is d~rected to new substituted allyl alkylene monomers and pclymers produced therefrom for use in water treatment. Specifically, the novel polymers of the invention comprise repeat units having the structure (with the inven~ive monomer represented as "Monomer h"):

~ 4 --FORMULA I

ll E ( Monomer g)CH2 -C- (Mollomer h) lH2 I :
l2 X : ~
wherein E in the above formula (Formula I) is the repeat unit obtained after polymerization of an ethylenically unsaturated compound or compounds, preferably carboxylic acid, amlde form thereof, or lower alkyl (Cl-C6) ester or hydroxylàted lower alkyl (Cl-C6) ester of such carboxylic acid. Compounds encompas~sed~ by E
include the repeat unit after polymerization of acrylic acid, methacrylic acid, acrylamide, maleic acid or anhydridel itaconic acid, vinyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid; and the like. Water soluble~salts forms of the carboxylic acids are also within the purview of the invention. ~ ~

One or more different structured monomers may be used as ~he E constitute provided that they fall within the definition of E
above given. One such preferred mixture of E monomers would be acrylic acid/2-hydroxypropyl acrylate.

Wi~h respect to Monomer h, Rl can be hydrogen or lower alkyl (Cl-C3); R2 is a hydroxy subst~tuted lower alkylene group having from 1 to 6 carbon atoms or a non-substituted lower alkylene group having from 1 to 6 carbon atoms, X is~ selected from the group - ' ' ' `' ' .

1 31 4qO4 consisting of CN, CONR3R4, and COOM, wherein R3 and R4 is independently hydrogen or lower alkyl (Cl-C3) and M is hydrogen, any water soluble cation (e.g., NH4, alkali metal) or a lower alkyl (Cl-C3).

The molar ratio g:h of the monomers of FORMULA I may fall within the range of between about 30:1 to 1:20, with the g:h molar ratio range of from about lO:l to 1:5 being preferred.

The number average molecular weight of the water soluble copolymers of FORMULA I may fall within the range of l,OOO to l,OOO,OOO. Preferably the number average molecular weight will be within the range of from about 1,500 to 500,000. The key criterion is that the polymer be water soluble.

Polymer structure of the present invention wherein X
is COOM is disclosed in U.S. Patent 4,659,481 (Chen) and European publication 0142929 (Chen).

PRIOR ARJ

U.S. Patent 4,500,693 (Takehara3 et. al.) discloses sundry copolymers composed of a (meth)acrylic acid monomer and an allylic ether monomer. Such polymers are disclosed as being useful dispersants and scale preventing a~ents that may be used in cooling water or water collection systems, etc. In accordance w;th the '693 disclosure, the allylic ether monomer may include, inter alia, the reaction product of allyloxy dihydroxypropane with various reagents, ,&

.

1 31 4qO~

such as, ethylene -oxide, phosphorus pentoxide, propylene oxide, monaryl sorbitan, etc. Polymers in this invention are not disclosed and can not be prepared by the '693 teaching.

U.S. Patents 4,659,480 and 4,708,815 (Chen et al.) disclose the reaction of allyl glycidyl ether with phosphorus acid (H3PO3) which results to allyloxy hydroxypropyl phosphite with a distinct C-O-P-H structure. Water soluble copolymer and terpolymer are then prepared using the phosphite containing monomer.

European Publication 0142929 (Chen) discloses water treatment polymers which are in many cases coextensive with those herein disclosed. The polymers are utilized to inhibit calcium phosphate and calcium phosphonate in aqueous systems. They also function to provide a passivated film along treated metal surfaces when they are used conjointly with a water soluble orthophosphate source.

U.S. Patents 4,659,481 (Chen) and 4,732,698 ~Chen) disclose the utilization of certain (meth~acrylic acidiallyl ether copolymers that may be utilized to pro~ide the elusive passive film along water system metallurgy when used conjointly with an orthophosphate ion source. Most sp~cifically preferred is utilization of an acrylic acid/2-hydroxypropylsulfonate ether copolymer.

U.S. Patents 4,659,482 (Chen) and 4,717,499 (Chen) disclose use of (meth)acrylic acid/allyl ether copolymers to simultaneously inhibit corrosion and calcium carbonate deposition in water systems under elevated pH (i.e., 7.5-9.0) and calcium carbonate supersaturation conditlons.

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U.S. Patent 4,701,262 (Chen) discloses the utilization of acrylic acid/allylhydroxyalkyl ether copolymers in combination with 2-phosphonobutane 1,2,4-tricarboxylic acid to inhibit calcium sulfate and calcium carbonate scale.

U.S. Patent 4,749,851 discloses utilization of acrylic acid/allylhydroxyalkyl ether copolymers to control calcium phosphonate scale in water systems.

Other prior art patents and publications which may be of interest include: U.S. Patent 4,490,308 and U.S. Patent 4,546,156 (Fong, et. al.). In the '308 and '591 patents, sulfonate group bonded to an allyl amide moiety is disclosedO They are different structures than the present invention where a hydroxylated~ alkylene allyl ether is connected to the carboxyla~e group.

DETAILED DESCRIPTION OF THE INYENTION

In accordance with one aspect of the invention, new water so1uble copolymers and terpolymers, as shown in ~Formula hereinafter, are synthesized using the inventive Monomer h. The water soluble copolymers and terpolymers of the ;nvention comprise repeat units having the structures:

~ .

1 31 4'~0~

FORMULA I

R
S
E (Monomer g) CH2 -C- (Monomer h) X :

wherein E in the above formula (Formula I) is the repeat uni~
obtained after polymerization of an ethylenically unsatura~ed~
compound or compounds, preferably carboxylic acid, amide~ form thereof, or lower alkyl (Cl-C6) ester or hydroxylated lower alkyl (Cl-C6) ester of such carboxylic acid. Compounds encompassed~by E ~ ~
20 include the repeat unit after polymerization of~ acrylic ~acid, ~ ;
methacrylic acid, acryamide, maleic acid or anhydride, itaconic acid, vinyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acidi and the like. Water soluble salts forms sf the carboxylic acids are also w1thin the purview of the~invention.

One or more different structure ~monomers may be~used dS~ ~ ~
the E constitute provided that they fall~ within the definition of E M
above given. One such prèferred mixture of E monomers would be acryliG ac~d/2-hydroxpropyl acrylate.

Wjth respect to Monomer ~h, Rl can be hydrogen or lower alkyl (Cl-C3j, R2 is a hydroxy~substituted lower alkylene group havin~ from l to 6 carbon atoms or a non-substituted lower alkylene group havln~ from l to~6 carbon atoms; X~is selected from the group : ' :

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1 3 i ~90~

consisting of CN, CONR3R4, and COOM, wherein R3 and R4 is independently hydrogen or lower alkyl (Cl-C3), M is hydrogen, any water soluble cation (e.g., NH4, alkali metal) or a lower alkyl (Cl-C3).

The number average molecular weight of the water soluble copolymers of Formula I may fall within ~he range o~ 1,000 to 1,000,000. Preferably, the number average molecular weight will be within the range of about 1,500 to about 500,000. Molecular weights of the copolymers are not critical so long as the resulting copolymers are water soluble.
: ' The molar ratio g:h of the monomers of FORMULA I may fall within the range of between about 30:1 to 1:20, with the g:h molar ratio range of from about 10:1 to 1:5 being preferred.
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SYNTHESIS OF MONOMERS

With respect to the monomer designated as Monomer g herein-above, these monomers may be prepared in accordance with well known techniques. For instance, one such possible monomer, acrylic acid,~
may be prepared by hydrolysis of acrylonitrile or by oxidation of acrolein.

With respec~ to the inventive allyl monomer (Monomer h)9 this monomer may be prepared in accordance with the ~disclosure of U.S. Patent 4,659,481 (column 3 and 4) using allyl glycidyl ether (AGE) as a reactant or via the reaction of allyl alcohol and chloro-~ hydroxy butanoic acid. When using allyl glycidyl ether as the reactan~, Monomer h may conveniently be prepared via a ring opening reaction of the epoxy group of an allyl glycidyl ether 131~90~

precursor with cyanide. Such reaction is similar to the ethylene cyanohydrin process in the making of acrylic acid. The reaction will produce the nitrile group and hydroxy group on allyl glycidyl ether. The resulting nitrile moiety (I) can be further hydrolyzed with acid or base to give amide (II), carboxylic acid/carboxylate compounds (III/IY), or a mixture of those above, depending on the reaction conditions. The reaction is illustrated by the following equations:

A. CH2=CH-CH2-0-CH2-CH--~CH2 + KCN ~ CH2=CH-CH2-0-CH2-CHOH-CH2-CN
`O aqueous (AGE, allyl glycidyl ether) (I, nitrile) + O
H or OH
B. CH2=CH-CH2-0-CH2-CHOH-CH2-CN ~ CH2-CH-CH2-~4 H2-CHOH-CH2-CNH2 (I, nitrile) (Il, amide) Il: I
+ CH2=CH-CH2-0-CH2-CHOH-CH2-COH or CH2=CH-CH2-0-CH2-CHOH-CH2-CO
(III~ carboxylic acidj ~ ~IY, carboxylate3 The IUPAC nomenclature for compounds I, Il, and III are:
I butanonitrile, 3-hydroxy-4-(2-propenyloxy) II butanamide, 3-hydroxy-4-(2-propenyloxy) III butanoic acid, 3-hydroxy-4-(2-propenyloxy) The structures of compounds I, II, and IIItIY were substant~ated by 13C NMR spectroscopy and IR ~spectra. The 13C NMR showed a distinct CaN peak at 118 ppm for Compound I and the amide (CONH) peak at 176.5 ppm for Compound II. The carboxylate (COO) peak, depending on the extent of neutralization, was observed around 179-181 ppm for Compounds III or IV. The IR spectra also identified the C-N stretch at 2253 cm-l for Compound I. The intermediates such as nitrile (I) and amide (II) compounds may be isolated respectively. Since amide is easily hydrolyzed with acid or basic treatment, the resulting carboxylic acid or carboxylate compound (III or IV) is the more common product. In the ring reaction of allyl glycidyl ether (AGE, Equation A), a small amount of unreacted AGE may be hydroly ed to glyceryl allyl ether. Without further purifica~ion, both AGE and glyceryl allyl ether can be copolymerized with Monomers g and h in Formula (I). Therefore, they are also within the scope of this invention. During the reaction (equation A
and B), a trace of side reaction products were also noted by 13C
NMR, which can be separated from the preferred products (III/IV).
It is to be understood that the method of removal of these impurities, does not in any way limit~the practice of the present invention. ~ ~

It is noted that hydrogen ion present in the carboxylic acid compound ( I l I ) may be replaced with Na, K, NH4+, or any water soluble cation. The hydrogen ion may also~be replaced by an~organic amine group or lower alkyl group of from about 1-3 carbon atoms.
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The carboxylic acid compound (III or IY) may also be prepared by reacting allyl alcohol with an ester of 3,4 epoxy butanoic acid (Y~ which can be synthesized from epoxidation of the ester of 3-butenoic acid. The reaction is illustrated by the following equations: ~
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1 3 1 ~qO~

C. CH2=CH-CH2COOCH3 + m-chloroperbenzoic acid (methyl 3-butenoate) / \
CH2 ~ CH-CH2 COOCH3 (~, methyl-3,4 epoxy butanoate~

D. CH2=CH-CH2-OH + / \

allyl alcohol (V) CH2=CH-CH2-0-CH2-CHOH-CH2COOCH3 (VI, methyl ester of III) The resulting ester (VI) may be further hydrolyzed into the free acid (III) or used directly for polymerization. Protecting groups other than me~hyl ester such as~ ethyl, propyl, amino groups etc. may also be used for this reaction. It is understood that the above methods of synthesis of the monomer h do not limit the methods of preparation of the said monomer.

POLYMERIZATION
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The novel monomers of this inven~ion may be polymerized to form homopolymers, copolymers with other monomers of this invention, or copolymers with other vlnyl monomers. ~ ~

After the desired monomers are produced and isolated, polymerization may proceed in solution, suspension, bulk, emulsion or thermal polymerizating form. For instance, in suspension 1 31 ~904 !

polymerization, the reaction may be in~tiated by an azo compound or an organic peroxide, with the monomers suspended in hexane or other organic reagents. On the other hand, in solution polymer;zation, the reaction may be initiated via conventional persulfate, peroxide, or vazo type initiators. Commonly used chain transfer agents such as lower alkyl alcohols, amines or mercapto compounds may be used to regulate the molecular weight. An accelerator such as sodium bisulfite or ascorbic acid may also be used.

The fact that polymers were formed by the above method was substantiated by viscosity increase and 13C NMR spectroscopy. The 13C NMR spectra showed a broad polymer type backbone (30-45 ppm), complex C-O region (62-74 ppm), broad carbonyl region (179 ppm), and disappearance of allyl or vinyl peaks.

It should be mentioned that other water soluble terpolymers comprising Monomers g and h of Formula I may alsq be prepared. For instance, l-allyloxy-2-hydroxypropyl sulfonate or 2-acrylamido-2--methylpropyl sulfonic acid may be incorporated into a water soluble polymer backbone having repeat units from Monomers g and h. Therefore, they are al50 within the scope of the invention.

The specific preferred polymer is a copolymer of acrylic acid/allyloxy-3-hydroxybutanoic acid ~III)/(IY)` comprising repeat units having the structure:
. .

1 31 4qO4 FORMULA II
--[CH2-CH-]-~ CH2-CH-~
1 9 I h C=O IH2 OH l CHOH

COOM
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wherein M is the same as in Formula I. ~ The molar ratio g:h~of the monomers of FORMULA II may fall within the range of:between about 30:1 to 1:20, with the g:h molar ratio range of from:about 10:1 to:
1:5 being preferrecl.

The number average molecular weight of the water soluble :
copolymers of FOR~MULA II may fall within the range o~ l,OOO~ to ; :
1,000,000. Preferilbly the number average molecular weight will:be within the range of from about 1,500 to:5QO,OOO.~ Molecular we:ights ~ : :
of the copolymers are not critical so :long as the::~copalymers ~are water soluble.

Deposlt Control The polymers of the invention should~be added to :the ;
:aqueous system, for which deposit~control activity or ~inhibiting the ~
corrosion of metal parts in contact with an aqueous medium is : ~;
desired, in an amount ef~ective for the purpose. This amount will vary depending upon the particular system for which ~reatment is ~ :

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desired and will be influenced by factors such as, the area subject to deposition, pH, temperature, water quantity and the respective concentrations in the water of the potential scale and deposit forming species. For the most part, the polymers will be effective when used at levels of about 0.1-500 parts per million parts of water, and preferably from about 1.0 to 100 parts per million of water contained in the aqueous system to be treated. The polymers may be added directly into the desired water system in a fixed quantity and in the s~ate of an aqueous solution, continuously or intermittently.

The polymers of the present invention are not limited to use in any specific category of water system. For instance, in addition to boiler and cooling water systems, the polymers may also be effectively utilized in scrubber systems and the like where;n the formation and deposition o~ scale formi~ng salts is a problem. Other possible environments in which the inventive polymers may be used include heat distribution type sea water desalting apparatus, dust collection systems in iron and steel manufacturing industries, and as a dispersant in the pulp and paper processing industries. A1SG
the polymers could be used as mineral beneficiation aids such as in iron ore, phosphate, coal, and potash recovery.

The water soluble polymers of the present invention can also be used with topping agent components in order to enhance the corrosion inhibition and scale controlling properties thereof. For instance the polymers may be used in combination with one or more kinds of compounds selected from the group consisting of inorganic phosphoric acids and water soluble salts thereof, phosphonic acids and wa~er soluble salts thereofg organic phosphoric acid esters, polyamino carboxylic acids and water soluble salts thereof, and 131~904 polyvalent metal salts capable of being dissociated to polyvalent metal ions in water, etc. Such topping agents may be added to the system in an amount of from about 1 to 500 ppm. Examples of such agents are disclosed in columns 5, 6, and 7 of U.S. Patent 4,659,481.

Examples The invention will be further described with re~erence to a number of specific examples which are to be regarded solely as illustrative, and not as restricting the scope of the invention.

Example 1 Preparation o~ Butanonitrile, 3-hydroxy-4-/2-propenyloxy)- (I) Anhydrous magnesium sulfate (61 9, 0.5 mole) and potassium cyanide (66 9, 1.0 mole) were dissolved in 440 ml deionized water at 10+/-2C under nitrogen. Allyl glycidyl ether (116 9, 1.0 mole) was ~hen added over a period of two hours ~with cooling to ~aintain a reaction temperature of 10+/ 2C. After addition, ~he reaction mixture was stirred at room temperature overnight. The resulting suspenslon was filtered and the precipitate was fur~her washed with 250 ml of deionized water and filter~d. The two filtra~es were combined together and concentrated in vacuo. The concentrate was then twice washed with 125 ml of methanol and filtered. The filtrate was concentrated in vacuo to yield a clear liquid.

The 13C NMR showed the product at 22.7, 66.0, 72.19 72.5, 117.?9 118.6 and 134.7 ppm downfield from external dioxane standard. No o~her organic species were detected by NMR
spectroscopy.

1 31 4~04 Example 2 Preparation of Butanoic acid, 3-hydroxy-4-(2-propenyloxy)- sodium salt (IV) A solution of 50% aqueous sodium hydroxide (16 9, 0.2 mole), 60 ml deionized water and butanonitrile, 3-hydroxy-4-(2-propenyloxy)- (30 9 Example 1, 0.2 mole) were heated at 98+/-2C for three hours under nitrogen. The resulting solution was a clear lîquid.

13C NMR showed the product at 41.4, 68.0, 71.9, 73.6, 117.9J 134.3 and 179.5 ppm downfield from external dioxane. A trace of minor side products were also noted in the spe tra.

Example 3 Preparation of Acrylic Acid/Butanoic acid, 3-hydroxy-4-(2-propenyloxy)- sodium salt Copolymer. Molar Ratio 6,0/1.0 A solution of 33% aqueous butanoic acid, 3-hydroxy-4-(2-propenyloxy)- sodium salt (28 9 Example 2, 0.05 mole) and 75 ml deionized water was heated ~o 95+/-2C under nitrogen. Acrylic dcid (22 9, 0.3 mole) and 20% aqueous sodium persulfate (13 9) were then simultaneously charged over a ~hree and one half hour period. After addition, the batch was held at 95~/-2C for two hours.

The resulting clear copolymer solution had a Brookfield viscosity of 24 cps at 25C (at 24% solids, pH 3.90). The structure of the copolymer was verified by 13C NMR. The spectrum was characterized by a broad poly (acrylic acid) type backbone (30-45 1 3~ ~04 ppm), broad carbonyl region (179 ppm), and peaks at 38.9, 66.9, 73.7 and 176.2 ppm downfield from external dioxane. No residual monomer was detected.

Example 4 Preparation of Acrylic acid/Butanonitrile, 3-hydroxy-4-(2-propenyloxy)- Molar Ratio 6.0/1.0 Butanonitrile, 3-hydroxy-4-~2-propenyloxy)- (7 g Example 1, 0.05 mole) and 90 ml deionized water were heated to 65+j-2 C
under nitrogen. A solution of 2,2'-azobis (N,N'-dimethylene iso-butyramidine) dihydrochloride (Wako VA-044, 7 9, 0.02 mole) and 16 ml deionized water was then charged to the batch. Acrylic acid (22 9, 0.3 mole) was then charged over a one and a half hour period with heating, maintaining a batch temperature of 65+/-2C. After addition, the batch was held at 65+/-2C for one hour.

The resulting clear copolymer solution had a Brookfield viscosity of 11 cps at 24C (at 25% solids, pH 1.9). The structure of the copolymer was verified by 1~3C NMR. The spectrum was characterized by a broad poly~acrylic acid) type backbone~ (30-45 ppm), broad carbonyl region (179 ppm) and peaks at 22.0, 65.5j 72.3 and 119 ppm downfield from exte`rnal dioxane. No residual monomer was detected.

Example S

Preparation of 8utanoic acid, 3-hydroxy-4~(2-propenyloxy)- potassium salt (IV).

*Trade mark ~ 31 ~90~

The compound of Example 2 can also be prepared by the following method: Potassium cyanide (33 9, O.S mole) was dissolved in 190 ml deionized water at 3+/-2C under nitrogen. Allyl glycidyl ether (AGE) (58 9, 0.5 mole~ was then added over a period of one 5 hour with cooling to maintain a batch temperature of 5+f-2C. After addition, the reaction mixture was stirred at room temperature overnight. The reaction was monitored by 13C NMR. The spectra showed the presence of the intermediate nitrile (I, 120.6 ppm), the amide (II, 176.5 ppm), the acid (IV, 179 ppm) compounds, and a minor 10 amount of glyceryl allyl ether (GAE) ~rom the hydrolysis of AGE.
The batch was then heated at 98+/-2C for thirty hours with a nitrogen purge. A 13C NMR spectrum of the batch at this point showed that the desired product (IV) was obtained along with a minor 15 amount of GAE and a trace of other side products. No amide (II) was detected at this point. The batch was then concentrated in vacuo and extracted with acetone (8 x 150 9) to yield a taffy-like material. The remaining acetone was decanted ~off, the residual dissolved in 700 ml deionized water and the resulting solution was ?0 concentrated in vacuo. The resulting clear solution was adjusted to 35% ~solids with deionized water.

The 130 NMR showed ~he product at 41.3, 67.9, 71.7, 73.5, 118.1, 134.~ and 179.3 ppm downfield from external dioxane. No GAE
25 was detected9 but a trace of other minor side reaction prGducts were noted.
:
Example 6 30 Preparation of Acrylic Acid/Butanoic acid, 3-hydroxy-4-(2-propenyloxy)- potassium salt Copolymer. Molar Ratio 6.0/1.0 1 31 ~904 A solution of 30% aqueous butanoic acid, 3-hydroxy-4-(2-propenyloxy)- potassium salt (33 g Example 5, 0.05 mole) and 75 ml deionized water was heated to 98+/-2C under nitrogen. Acrylic acid (2~ 9, 0.3 mole) and 20% aqueous sodium persulfate (13 9) were then simultaneously charged to the flask over a three and one half hour period. After addition, the batch was held at 98+/-2 C for two hours.

The resulting clear copolymer solution had a Brookfield viscosity of 46 cps at 25C (at 25% solids, pH 3.96). The structure of the copolymer was verified by 13C NMR. The spectrum was characterized by a broad poly(acrylic acid) type backbone (30-45 ppm), broad carbonyl region (179~ppm), and peaks at 38.9, 66.9~ 73.7 and 176.2 ppm downfield from external dioxane. No residual monomer was detected.

Passivation Although the polymers of the invention, when used singly, may not adeqùately inhibit corrosion, the demonstrated efficacy of polymers of similar structure in inhibiting calcium phosphate precipitation is very important. For instance, one successfully established cooling water treatment ~method provides a passivated film on metal surfaces in contact with the aqueous medium via addition of orthophosphate, organo-phosphonate and an acrylic acid/hydroxylated alkyl acrylate copolymer. Details of such method are disclosed in U.S. Patent 4,303,568 (May et. al.). It is expected that the subject copolymers can be substituted for the polymers disclosed in the aforementioned May et al. and Chen r ~;.

~ 3~ 4~

patents so as to provide the important passivated film on the desired metal surfaces.

As is stated ;n the May et. al. patent, the passive film is provided on metal surfaces in contact with the aqueous medium without substantial attendant deposition formed thereon. A
composition containing polymer and orthophosphate and optionally but preferably a phosphonate, polyphosphate and copper corrosion inhibitors is used in order to achieve such passivation. A typical composition contains on a weight ratio bas;s of polymer to orthophosphate expressed as P04--- of about l:8 to 4:1 and preferably about 1:6 to 2:1. When a polyphosphate* is included, the weight ratio of orthophosphate to polyphosphate on a P04--- basis is lS:l to l:3, and preferably 2~3:1 to l:1. Similarly, if the organo-phosphonate is included, the ratio of the orthophosphate to the phosphonate expressed as P04 to P04---- is l:2 to l3:l, and preferably 2:1 to 8:1. Any copper corrosion inhibitor may be included in the composition (O.Ol to 5% by weight) i~n an amount which will be effective for controlling the copper corrosion in a given system: 0.05 to lO parts per million and preferably 0~.5 to 5 parts per million. Similarly, zinc salts ~may be included if additional protection is needed.
;
In treating the aqueous systems to provide such passivation, the following dosages in ~parts per million parts of water in said aqueous systems of the respective ingredients are *Handbook of Industrial Water Conditioning, 6th edition, 1962, pages 394-396, Betz Laboratories9 Inc., Trevose, PA.

! . ~

. . . ,' ' . ' , ` ' 1 31 ~904 desirable, with the dosages, of course, being based upon the severity of the corrosion problem foreseen or experienced:

orthophosphate (expressed as P04~ 2 to 50 parts per million parts of water (ppm) and preferably 6 to 30 ppm;
polymer: 0.3 to 120 ppm and preferably 3 to 25 ppm;

polyphosphate (expressed as P04---): 0.1 to 30, and preferably 3 to 10, parts per mlllion parts of water;

phosphonate (expressed dS P04---): 0.04 to 20, and preferably 1 to 6, parts per million parts of water.

The preferred rate of application of this treatment to cooling water systems and the ratios of various components depends on the calcium concentration of the cooli~ng water. The treatment is pre~erably applied in waters having between 15 ppm ~and 1,000 ppm calcium. Within this range the weight ratio of calcium to ortho-phosphate is Yaried from 1:1 to 83.3:1, the weight ratio o~ polymer to orthophosphate is varied from 1:3 to 1.5:1.

The orthophosphate which is ~critical to passivation is generally obtained by direct addition. However, it is understood that the orthophosphate can al 50 arise due to reversion of either inorganic polyphosphates or the organo-phosphonates, or any other appropriate source or precursor thereof; however, significant reversion is required.

The above dosages represent the most desirable~ ranges since most systems will be treatable therewith. Higher dosages are 1 31 ~904 permissible when the situation demands, but of course are most costly. The effectiveness of the inventive treatments are dependent upon the aqueous medium having a pH of 5.5 and above, and preferably 6 5 to 9.5, and containing calcium ion concentrations, preferably about 15 parts per million parts of water. Below this range3 it may be necessary for overall effectiveness to add metallic ions such as zinc, nickel, chromium, etc. as described in column 3, lines 4 to 24 of U.S. Paten~ No. 3,837,803.

While this invention has been described with respect to particular embodiments thereof, it is apparent that numerous o~her forms and modifica~ions of this invention will be obvious to those skilled in the art. The appended claims and this invention generally should be construed to cover all such obvious forms and modifications which are within the true spirlt and scope of the present invention~

Claims (20)

1. A water soluble polymer comprising substantially repeat units having the structure:

E (Monomer g) (Monomer h) wherein E in the above formula comprises the repeat unit remaining after polymerization of a compound or compounds selected from the group consisting of acrylic acid, methacrylic acid acrylamide, maleic acid or anhydride, itaconic acid, sodium vinyl sulfonate, sulfonated styrene,

2-acrylamido-2-methyl-propane sulfonic acid, diallyl dimethyl ammonium chloride, lower alkyl ester or hydroxylated lower alkyl ester of said acids; wherein R1 is hydrogen or lower alkyl; R2 is a hydroxy substituted lower alkylene group having from 1 to 6 carbon atoms or a non-substituted lower alkylene group having from 1 to 6 carbon atoms; X is selected from the group consisting of CN and CONR3R4; wherein R3 and R4 are independently hydrogen or lower alkyl; the molar ratio g:h of said polymer being between about 30:1 to 1:20.

2. The polymer as recited in claim 1 wherein E comprises acrylic acid repeat unit and 2-hydroxypropyl acrylate repeat unit.

3. The polymer as recited in claim 1 wherein R1 is hydrogen, R2 is 2-hydroxypropylene, and X is CN.

4. The polymer as recited in claim 1 wherein R1 is hydrogen, R2 is 2-hydroxypropylene, X is CONR3R4, and R3 and R4 are independently hydrogen or lower alkyl.

5. The polymer as recited in claim 4 wherein R3 and R4 are hydrogen.

6. The polymer as recited in claim 1 wherein R1 is hydrogen and R2 is 2-hydroxypropylene.

7. The polymer as recited in claim 1 wherein the molar ratio g:h is about 10:1 to about 1:5.

8. Method of controlling the deposition of scale imparting preciptitates on the structural parts of a system exposed to an aqueous medium containing ox prone to the formation of scale imparting precipitates under deposit forming conditions, said method comprising adding to said aqueous medium, an effective amount of the water soluble polymer having repeat units of the structure:

E ( Monomer g ) ( Monomer h ) wherein E in the above formula comprises the repeat unit remaining after polymerization of a compound or compounds selected from the group consisting of acrylic acid, methacrylic acid acrylamide, maleic acid or anhydride, itaconic acid, sodium vinyl sulfonate, sulfonated styrene, 2-acrylamido-2-methyl-propane sulfonic acid, diallyl dimethyl ammonium chloride, lower alkyl ester or hydroxylated lower alkyl ester of said acids; wherein R1 is hydrogen or lower alkyl R2 is a hydroxy substituted lower alkylene group having from 1 to 6 carbon atoms or a non-substituted lower alkylene group having from 1 to 6 carbon atoms; X is selected from the group consisting of CN and CONR3R4; wherein, R3 and R4 are independently hydrogen or lower alkyl; the molar ratio g:h of said polymer being between about 30:1 to 1:20.

9. Method as recited in claim 8 wherein E comprises acrylic acid repeat unit and 2-hydroxypropyl acrylate repeat unit.

10. Method as recited in claim 8 wherein R1 is hydrogen, R2 is 2-hydroxypropylene, and X is CN.

11. Method as recited in claim 8 wherein R1 is hydrogen, R2 is 2-hydroxypropylene, X is CONR3R4, and R3 and R4 are independently hydrogen or lower alkyl.

12. Method as recited in claim 11 wherein R3 and R4 are hydrogen.

13. Method as recited in claim 8 wherein R1 is hydrogen and R2 is 2-hydroxypropylene.

14. Method as recited in claim 8 wherein the molar ratio g:h is about 10:1 to about 1:5.

15. Method as recited in claim 8 wherein said water soluble polymer is added to said aqueous medium in an amount of from about 0.1 - 500 parts polymer based upon 1 million parts of said aqueous medium.

16. Method as recited in claim 8 wherein said aqueous medium comprises a steam generating system.

17. Method as recited in claim 8 wherein said aqueous medium comprises a cooling water system.

18. Method as recited in claim 8 wherein said aqueous medium comprises a gas scrubbing system.

19. Method as recited in claim 8 wherein said aqueous medium comprises a pulp and paper manufacturing process.

20. Method as recited in claim 8 further comprising, adding to said system, an effective amount for the purpose of a topping agent selected from the group consisting of inorganic phosphoric acids and water soluble salts thereof, organic phosphoric acid esters and water soluble salts thereof, polyamino carboxylic acids and water soluble salts thereof, and polyvalent metal salts capable of being dissociated to polyvalent metal ions in water.