CA1326430C - Method for barium sulfate and/or calcium oxalate scale control - Google Patents

Abstract

Abstract of the Disclosure Methods of Controlling the formation of calcium oxalate and/or barium sulfate scale in aqueous systems are disclosed. The methods comprise adding from about .1 to 500 ppm of a water soluble (meth)acrylic acid/allyl ether copolymer to the desired water system. The methods are especially well adapted for use in pulping and paper making systems wherein calcium oxalate and/or barium sulfate is often encountered as a troublesome scale forming compound.

Description

~32~3~

METHOD FOR BARIUM SULFATE AND/OR CALCIUM OXALATE SCALE CONTROL

Field of the Invention The eeesent invention ~e~tain~ to a method of controlling calcium oxalate and/or ba~ium sulfate ~cale formation in an aqueous system by using certain copolymers of (meth)acrylic acid and allyl ether ba~ed monomer~.

- Backqround o the Invention In the paper~aking proeess, caleiu~ oxalate scale often form~ on proeesa eguipment during the bleaching~delignification of pulp by ehlorine, caustie soda, ehlorine dioxide, hypoehlorite and peroxide. ~sual areas of scale build-up are on washer drw~ face wires; in washer vats; in stoek line~ and pu~ps; in filtrate tank~, lines, and pumps; on extraetion sereens: and in treatment towers. The for~ation of ealeiu~ oxalate ~eale provides an eeonomie hardship on ~ills prineipally beeau~e of lost produetion due to deereased bleaehing~deliqnifieation effie~eney and eqyip~ent downti~e assoeiated with the removal of seale.

.~

.
. ~

.. . . ...
,.. ~ ,, . .. =, .. . . .
.. , . , . . .~ .. ..

" 1~26~3~

One option available to pulp mill~ to attempt to prevent this scale build-up has been the use of continuously fed scale control agents. ~istorically, these additives have included polyphosphates, organic phosphonic acids, ligno~ulfonates, and various water ~oluble polycarboxylates. ~owever, recent industrial trends to recycle water in order to reduce blea~h plant effluent volumes for environmental reasons and the use of calciw~ carbonate laden paper ~achine white water a~7 bleach plant process water are expected to increase tbe frequency and severity of calcium osalate scale for~ation.
Moreover, increases in bleach plant hardness and oYalate levels associated with these trends have caused some of the convèntional scale control agents to fail because of their inability to function under condition~ ~hich pro~ote extensive scale for~ation, na~ely high le~els of calciu~
and,.o,xal.ateO
In the pulp and paper industry, the problem of bariu~ sulfate deposition has only recently been addressea. ~he proble~ doe~ not seem to be i~olated to any particular geographic region, since it has been seen on ground~ooa ~achinea, fine paper ~achine~ ana unbleached kraft ~ach~ne~ in all part~ of thc ~nited State-.
Generallr, the deposits ha~e heen found in the ~creens, cleaner~, fan pu~p, organ tube~, headbox, rectifier rolls, headbox lip and lice, ana on the Fourarinier foiln.
~he~e depo~it- can lead to for~ation proble~, fiber ~ bundle- or ~t~i~t-~ cooing loo~e and caudng hole~ in the ~heet, and even paper maahine break~ due to crushouts at - ~ the pres~e~. Deponition àl~o pro~ide~ a favorable location for ~ulfatc reducing bacteria to fester, leading e~entuall~ to coFro~ion problem~ and subse~uent ~3~ 132643~

papermaking problems. Where bariu~ sulfate depGsition problems haYe been especially severe, dollar losses can be attributed to lost production because of off-seec paper and cleaning downtimes, labor and mechanîcal cost~ of cleaning, and shortened equipment life because of corroded headboxe~. The problem i~ especially acute due to the low aolubility of the compound in water.
The proble~ of barium sulfate scale formation has been experienced for ~Rny years in the petroleum inaustry wherein its formation in drilling case~
surrounaing mud slurries and the like has impeded petroleum recovery and has caused fouling ana de~osit formation along drilling i~plements and oil recovery _line~, ~
SummaeY of the Invention We have found that calcium oxalate scale and/or barium sulfate scale may be adequately conteolled by.adding to the desired aqueous system, such as a eulP and eaeermaking aqueou~
system, fcom about .5 to about 500 eem of a water soluble ~meth)acrylic acid~allyl ether copolymer, based on one ~illion part~ of the aqueou~ ~yste~.

-4- 1326~30 The (~ethlacrylic acidiallyl etber copolymers~
u~eful in accordance with the invention, ha~e the structure R~
--IEI-- --ICE~CEII -c I d c~
o ~a, (Xz) ~ . a wherein E i8 the repeat unit remaining after polymerization of an~L, ~, ethylenically un~aturated compound, R~, is ~ or lower ~C~-C.) alkyl, R, i8 ~C8.-c~-0)~8, (c8~-cs-o~8~ ~onohydrox~lated C,-C8 C~, alkyl, monohydroxylated C~-C. alkylene, di- or polyhydroxy C~-C8 al~yl, dihydroxy or polyhydroxy C~-C8 alkylenc, C~-C8 alkyl, or C~-C~ alkylene, n i~ an integer of rom 1 to about 20, a i8 0 or 1, X, wheA present, i~ an anionic radical selected fro~ the group con-i~ting of S0., PO~, P0~, and oO0, ~, when prescnt, i~ 8 or hydrogens or a water ~olublc cation or cat}ons, Z being chosen to counterbalance thc ~alence o X, X,Z co~bined ~ay also . '.
denote an a ine functionality of the for~ula . . .
: . ~

132643~
s~z 003 P2A3 -5--- ~N - F, wheeein F~ F. and F. are in~ependently ~elected rom ~, a~d C~-~ alkyl, C~-C5..hydroxy-sl~stituted or carboxy-substituted alkyl, the ~olar ratio of repeat units c:dbeing from a~out 30:1 to about 1:20.
- In accordance with the method, from O.l to 500 part~ of the (meth)acrylic acid~allyl ether copolymer are admitted to the desired agueous system, ba~ed upon one million parts o the aqueous system.

Pcior Art The water ~oluble or water diseersible copolymers used in accordance with the invention to control calcium oxalate and/o~
barium sulfate scale are not new. For instance, ~.S. Patent ~,500,693 ~Takehara et al) di6closes water soluble copolymer~ ha~ing an acrylic acid or methacrylic acid repeat unit ~hich i~ co-polymeri~ed ~ith certain allyl ether ~onomer~ e polymers di~clo~ed in accordance ~itb Takehara et al are useful calciu~
carbonate inhibitors and ~ay also be used a~ pigment dispersants.
.S. Patent ~,469,615 ~ssuruoka et al) discloses ~ater treat~ent co~positions co~prising a ~ater soluble copolymer having, a~ the co~ponents, one repeat unit formed fro~ an addition reaction product o a glycidyl ether or glrcidyl-e~ter and an ~, B ethylenically unsaturated carbo~yl~c acid. She ca-~ono~ee ~ay comprise .

- 132~`~3~

any vinyl monomer. The copolymers are reported a~ being useful aff corrosion inhibition agents in ~ater system~.
Japanese Patent Publication S~056-155692, ~Method o Collecting Dust~ discloses use of acrylic acid/polyethylene glycol monoallylether copolymers which are utilized to treat the recirculating water in an aqueous dust collectinq ~ystem. In this disclosure, the number o woles of etho~ylation i8 taught as being rom 5 to 100. If the nu~ber is le~s than 5, the scale control and di~persant efficacie~ are insufficient.
~ offenlegungs~chrift 25 22 637 discloses varied acrylic acid type copolymer~ which may he utilized to stabilize haraness in water systems.
European Publication 01~2929 aisclose~ water treat~ent poly~ers which are in many cases coextensive ~ith those herein aisclo~ed. The poly~ers are utilized to inhibit calciu~ phosphate and calciu~ phosEbonate in aqueou~ ~yste ~. They also function to provide a passivated oxide fil~ along treated metal ~urfaces when they arc used con~ointly with a water soluble orthophosphate source.
.S. Patents 4,659,481 IChen) and ~,732,698 ~Chen) disclose the utili~ation of certain ~meth)acrylic acid~allyl ether copolymer~ that ~ay be utilized to provide the elu~ive passive oxidc fil~ along ~ater system metallurgy ~hen used con~ointly ~ith an orthophosphate ion source. ~bst ~pecifically preferred i8 utilizat~on of an acrylic acia~2-hydro~yeropylsulfonate ether copolymer.

, . .. . .

1326~3~

~ .S. Patents 4,659,482 (Chen) and 4,717,499 (Chen) diselose use of (meth)acrylic acid/allyl ether copolymers to simultaneously inhibit corrosion and calcium carbonate depo~ition in water systems under elevated p~
~ ~i.e., 7.5-9.0) and calciu~ carbonate supersaturation conditions.
- ~.S. Patent 4,701,262 (Chen) discloses the utilization of acrylic acid/allylhydroxyalkyl ether copolymers in combination with 2-pho~phonobutane 1,2,4-tricarboxylic acid to inhibit calcium sulfate and calcium carbonate ~cale.
U.S. P2tent 4,759,851, discloses utilization of acrylic acid/allylhydroxyalkyl ether copolymers to control calcium phosphonate scale in water'sy~ems.
a.s. Patents 4,659,480 (Chen et al) and 4,708,815 (Chen et al) disclose utilization of certain acrylic acid/allyl alkylene phospbite ether copolymers in water,~rea,tment systems.
U.S. Patent 4,560,481 (~ollander) discloses utilization of acrylic acia~allylhydroxypropylsulfonate ether copolymers to control iron-ba~ed fouling in cooling water system~. ~.S. Patent 4,671,880 Wisener et al discloses use of such polymers to control alum carryover " from clarifiers, etc.
~.S. Patent 4,693,829 ~Boffardi) disc10ses utilization of acrylic acid~2-acrylamido-2-methyl propane sulfonic acid copolymers for barium sulfate inhibition.
~owever~ the disclosed copolymers contain amide'lin~ages which are not as thermally and hydrolytically stable as the copoly~ers of the present invention which contain ether linkageJ.
Proce~ses for controlling calcium oxalate scale over a ~ide p~ range are disclose~d in ~.S. P~ent 4,575,425 (Boffardi et al). In accordance with the discloJure, calciu~ oxalate in agueous systems i8 , A

~6~
-controlied by use of (al a water ~oluble phosphate, pho~phonate or pho~phinate and ~b) an anionic water soluble polyelestrolyte As to the anionic water soluble polyelectrolytes which ~ay be utilized the preferred polyelectrolytes are poly~ers o unsaturated carboxylic acids or salts thereof As example~, acrylic acid, methacrylic acid, copolymers of acrylic acid and methacrylic acid, copolymers of ~meth)acrylic acid and 2-acryla~ido-2-~ethyl propane sulonic acid, copolymers of acrylic acid and 2-hydrosyproprl acrylate, and copolymers of metha~rylic acid and 2-hydroxypropyl acrylate are mentioned Ater reading the '425 disclosure, one s~illed in the art would not expect that allyl deri~ed ~onomers would be effecti~e a~ calciu~ o~alate dbpo~it control agents Other pa~ents which may be of intere~t to the present invention include U.S. Patent 3,549,548 (Newman) U.S. Patent 3,992,31~ (Gaupp et al); U.S. Patent 4,029,577 (Godlewski et al);
4,303,568 (May et al) 4,324,684 (Geiger et al).
Chcm Abstract- 99:58708X, 'Scale Inhibitor~ for Cooling ~ater Srstea', al~o appears to be of interc~t as the discloJed ~ale inhibitors comprise an acrylic or methacr~lic acid copolymer wherein the second ~onomer i8 formea froo a polyalkyle~e glycol monoallyl ether.
Chem ~b-Sract~ 98 203736r, 'Additives or Dust Scrubbi~g Liguor', discloses ~tilization o a copoly~er of polyalkylene glycol ~ono~llyl ether and methacrrlic acid.

. :. .

g Detailed DescriPtion of the Preferred E~bodi-en~
In accordance with the invention, it has been di~covered that certain water ~oluble copolymer~, as ~hown in Formula I
hereinafter, are effective in conteolling the formation of calcium oxalate andior barium sulfate deeosits in vaeious water sy~tems.
The poly~ers ~omerise repeat units composed of an~ ethylenically unsaturated compound and an allyl alkylene ether based compound.
The (meth)acrylic acid/allyl ether polymer~ u~eful in accordance with the invention have the structure R~
-IE } { C~l-C~I
c , I d CQ, O ~ FORM~LA I
R~
~XZ) ~herein E i~ thc repeat unit remaining ater poly~eriration of an~,8, ethylenically unsaturated co~pound, R~ is ~ or lower ~C~-C~) alkyl, ~ C~,-C~,-O)~ c~,-C~O)_~, c~, monohydro~ylatea C~-C~ alkyl, CE~

~onohydro~ylated C~-C~ alkylene, di- or polyhydro~y C~-C. alk~l, C~ ~ alkylene, n i~ an integer of froa 1 to about 20, a i~ 0 or f, i, w~en present, i~ an anionia radical ~clected froa the group consirting of SO~, PO,, .

. . . .

1~2~3~
--~o Po~, and coO, Z, when present, i8 8 or hydrogens or a water soluble cation or aation~, ~ being chosen to counterbalance the ~alence of X, X,Z combined may also denote an amine functionality of the formula F~
F, F~
wherein Fl, F2. F3 are independently 6elected from H, and Cl-C5 alkyl, Cl-C5 hydroxy-substituted or carboxy-substituted alkyl, the molar ratio of repeat unit~ c:d being from about 30:1 to about 1:20.
E in the above for~ula may, for instance, comerise the repeat unit obtained after polymerization of ano~ ethylenically unsaturated ~onomer, preferably a carboxylio acid, amide form thereof, or lower alkyl ~C~-C,~ e~ter or hydroxylated lower alkyl ~C,-C~ ester of such carboxylic acid. Exemplary comeounds encompassed by E inciude, but are not restricted to the repcat unit for~ed by polymeri~ation of acrylic acid, rethacrylic aci~, acrylamide, maleic acid or anhydride, fu~aric acid, itaconic acid, 2-hydroxypropy~ acrylate, atyrene ~ulfonic acid, and 2-acryla~ido-2-methyl proeane-sulfonic acid and the like. Water soluble salt for~ of ~hese acid- are also within the purview of the in~ention.
She second repeat unit in Fonmula I may include, a~ exe~plary repeat unit-, repeats unit~ for~ed fro~
mono era ~uch a~ l-allyloxy-2-propanol, l-allyloxypropane 2,3-diol ~glyceryl allyl ether), polyethylene glycol allyl cther, polypropyleneglycol allyl ~ther, l-allyloxypropane : . .

132~

2-hydroYy-~-sulfonic acid and water soluble salt-forms thereof.
The ~olar ratio c:d o the repeat units may fall withi~ the range of 30:1 to 1:20, ~ore de~irably within lS:l to 1:10.
The number average ~olecular weight of the water ~oluble copolymers of Formula I i8 not critical and may fall within the Mn range of from about 1,000 to l,OOO,OOG, desirably, l,000 to 30,000, and most desirably 1,500 to 25,000. The ~ey criterion is that the copolymer be water , solu})le.
~ he polymers may be prepared by conventional techniques such as those e~pressea in U.S. Patent 4,659,481 (Chen) and 4,708,815 ~Chen et ?l), both being of common assignment herewith, .. It is noted that in the case in which XZ in repeat unit td) i8 a~ auine functionality, the.
mono~er can be prepared in accordance ~ith the followinq mechanislo:

C~, = C - C~ - O - C~y - C~-~C~, ~ ,N - ~ ~r C~, --Cll - C~. ~ O - CE~, - CE~O~ - CE~
F~
For ~ak~ of brevity, suffice it here to state that these conventional techniques include frce raaical ~so1ution, precipitation or e~ulsion poly~erization technigye#.- - -Conventional poly~eri~ation initiators ~uch a#
: ... ., . - :

1i~2643~

persulfates, peroxide~, W light, etc. may be used.
Chain transfer agent~ such as alcohols ~preEerably isopropanol), amine or mercapto compounds ~ay be used to regulate the ~olecular weight of the poly~er. ~he resulting.polymer ~ay be isolated by well known technigue~
including precipitation, etc. If polymerized in water, the polymer ~ay ~imply be u~ed in it8 aqueous ~olution.
The polymers presently preferred for use are acrylic acidt2-hydroYypropyl sulfonate ether polymers of the formula:
' ~' EI
I _ I I I
~ c El C = O ~ C~, ' OM O Foemula II
c~, . ~
- ~C - 08 c~. .
So~M

~herein M i- ~ or a water 801uble cation, the ~olar ratio c:d being about 15:1 to 1:10. The optL~al nu~ber average molecular ~e~gbt ~Mn~ of the For~ula II copolymer i~ OA
the order of 1,000 to 30,000.
~, , Superior perfor~ance han al80 be howA by acrylic acid~l-allylosy-2-peopanol ~AOP) copolymers ~ illu~trated by the following Formula III:

.
. -1326~

- 1~

C ~ I ~d E~ C = O ~ CE~ , OM O Formula III-CE~

C~

M is as defined in Formula II, the molar ratio of c d i8 from about 15 1 to 1 10 and the molecular ~eight Mn of the copolymer i~ preferably about 1,000-30,000.
Another qroup of poly~ers showing particular promise are the acrylic acid~polyethylene glycol allyl ; ether polymer- baving the ~tructure ~ C - C ~ ~ ~ I ~d .'. ~ C = 0 11 C
OM. O
- C~, Foraula IV
C~

~ t'n ..

wherein n i~ roo 1 to about 20, preerably 1 to 15, c:d i8 fro~ 15:1 to l:lO, and wherein the preferred Mn molecular weight i~ about 1,000-30,000.
The polymers (Formulae I-IV) should be added to the aqueous ~ystem in which ~alcium oxalate and/o~ barium sulfate de~ofiit control activity is desired. in an amount effective for the purpo~e~ This amount will vary depending upon the particular syste~ for which treat~ent i8 desired and will be influenced by factors such as: hardness, p~, temperature, water quality and the respective - concentrations in the water of the potential scale and deposit for~ing species~ For the most part, the polymer~
~ill be effective when used at levels of about 0.1-500 parts per million parts of water, and preferably from about 1.0 to lO0 parts per million of water contained in the aqueou~ system to be treated. The polymers may be ~
added directly into the desired water system in a fixed guantity and in the state of an aqueous solution, continuoudy or inten~ittently.
~ he p~ly~ers of the present invention are not limited to use in any specific category of water system.
For in~tance, in addition to paper and pulp processing, the eolymers may al60 be effectively utilized in other water systems wherein calcium oxalate and/or barium sulfate scale control is important.
In an especially ~ignificant aspect of the in~ention, tbe calciu~ oxalate scale control agents herein di~clo~ed exhibit tbe characteristic of being highly calciu~ tolerant. By this, ~e ~ean, that unli~e some other kno~n anionic polyelectrolytes, the ~meth)acrylic ~2`1~

acid/allyl ether copolymers of the pre~ent invention are able to perform their intended caloiwm oxalate scale control function even in those waters having a high calciu~ ion content ~i.e., greater than about 300-400 pp~
as Ca~-). In contrast, some other anionic polymers selectively eeact with the high levels of ~alcium in the system water and are then unavailable to perform their intended scale control function.
The invention will now be further de~cribed with reference to a number of specific examples which are to be regarded solely as illustrative, and not as restricting the scope of the in~ention.
E~tamples The following e~amples deal with the preparation of the copolymers which have prove~n efficaciou~ in cont~olling calcium oxalate and/or barium sulfate ~cale~formation.
E~ample~ 1-6: Preparation of acrylic acid ~AA) allyl hydroxyproeylsulfoAate ethcr, sodium Jalt ~A8PS~ ) Shcse poly~ers were all prepared in substantial confor ity to the procedure given in Examples 1 and 6 of ~.S. Patent ~,659,481, with ~a~or exception~ being the relative ratio~ of reactants used and the ~olecular weight~ of the resulting poly~ers. EYample 1 of the '481 patent i~ repéated hereinbelow.
~ A~auitable reactloA flask was equipped with a - mechanical agitator, a thenDo~eter, a reflus condenser, a nitrogen inlet and two addition iAlets for the initiator ... .
.

and monomer solutions. The fla~k was charged with 200g of deionized water and 269 of isopropanol. The resulting solution was then heated to reflux under a nitrogen blan~et 72~ of acrylic acid ~ mole) and 1369 of l~propane ~ sulfonic acid, 2-hydro~y-3-~2-propenyl o~y) mono sodium salt IA~PSEl (40%, 0.25 mole) were miYed in a separate flask 80 a8 to provide a mixed monomer solution. ~he mixed monomer 801ution was then transferred to an addition funnel . An initiator solution containing 27.3% of ~odium - persulfate in deionized water was prepared separately and sparged with nitrogen. The initiator sclution (20 ml) was then added to the reaction flask along with the mi~ed monomer ~olution over a period of 2 hours. After this addition, the resulting ~ixture was heated for 2 more hours at 85C and ~ub~equently, 66.59 of the isoproeanolJwater ~olution was stripped off. She reaction misture ~as then cooled to less than 40C and 60g of 50%
aaustic ~olution was then added.
EYa~ple 7 : Preparation of Acrylic Acid (AA)~I-Allylo~y-2-propanol ~AOP) Copolymer of about 3~1 mole ratio AAfAOP.
A ~uitable reaction flask was equipped with a mechanical agitator, a thermo~eter, a reflu~ condenser, a nitrogen inlet and two addition inlets for the initiator and monomer solution~. ~he flask was charged with 2209 of deionized ~ater a~d 35g of isopropanol. Thc re~ulting aolutioA ~a- then heated to reflux under a nitrogen blan~et. In a ~eparate ~esJel, 43.29 ~0.6 mole) of acrylic acid aAd 23.29 (94~ pure, 0.19 mole) of 1-..

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allyloxy-2-propanol were miYed 80 as to provide a mîxed mono~er ~olution. ~he ~ixed mono~er solution was then transferred to an addition funnel. An initiator ~olution containing 24.4~ o sodiu~ persulate in deionized water was prepared separately and sparged with nitrogen. The initiator ~olution ~1791 was then added to the reaction flask along with the ~ixed mono~er 801ution over a period of two hours. After this addition, so~e additional persulfate solution wa~ added to the reaction mixture for ',''5 one more hour at 85C and, subsequently, lO9.0g of the i~opropanol/water 801ution were stripped off. The reaction mixture was then cooled to lower than 40C and 34g of 50% caustie solution was added.
The structure of the resulting polymer was verified by Carbon 13 NMR. The polymer solution, after being diluted to 2~.8% solids with water, had a Broo~ield visco~ity of 1~.7 cp~ at 25C. It wa~ rtable ~olution with a slightlr yello~ color. ~he ~olecular ~eight ~as IMn) was ~,000 as deten~ined by aP
E~ample 8:
~ tilizing the apparatus and procedure described in E~ample 7, ~3.29 of acrylic acid ~0.6 ~ole) and 129 of AOP 19~%, 0.097 mole) were used for copolymerization. The resulting poly~er solution, after being dilutea to 23.8%
solids had a Brookfield ~iscosity of 15.7 cps lat 25C).

~326430 Exa~ple 9: AAJpolyethyleneglycol (PEG) Allyl Ether Copolymer ~ tilizing both aeearatus and procedure similar to that de~cribed in Exa~ple 6, 120g of deionized watcr and-2~q of polyethylene~lycol allyl ether Iwith ~ moles of ethylene glycol) wese charged to a reaction flask. The solution was then heated to 90C under a nitrogen blanket.
21.69 of acrylic acid were then added to the reaction flask along with an initiator solution co~pri8ing ~odiu~
persulfate o~er a period of 1 hour. The reaction ~i~ture was heated for 3 ~ore hours and was subsequently cooled to lower than ~OC whil.e 169 of 50% caustic solution were added. C13 NMR showed that'no residual monomer was present.
The re~ultinq polymer solution~ after being diluted to 25~ ~ith-~ater, had a Brookfield viscosity of - 2~-cp~ ~at 25C). ~he ~olecular ~eight IMn) ~a- 7,500 a~
deter~ined by GPC.
Ex;~ple lOs AA/PEG Allyl Ether ~ til~zing the apearatus and procedure de~cribed in 8~a~plc 6, 21~69 of acrylic acid (0.3 ~ole) and ~8.1g of polyethyleneglycol al'lyl ether ~containing 9.6 ~oles of ethyleneglycol~ ~ere used for copolymeri~ation. The resulting eoly~er solution, after being diluted to 25.3 had a Brookfleld vi~co~ity of 22.6 Cp8 ~at 25C~. The ~olecular ~eight ~a- 5,100 a~ ~easured by GPC.
~ aqele~ 18 ,~ere prepared by the s~ilar , ~ethods as des,cr~bed above., ' Table I hereinbelow ~resents a ~umma~y of the - phy~ical propertie- of the copolyme~s. `"

- - lg 132~3~

Table I
Copolymer Properties Viscosity, cps Brookfield #
Copolymer CompositionMole Ratio 25~, 25C Mn Example 1 AA/AHPS 3:1 15.8 6,900 Example 2 AA/AHPS 3:1 14.9 5,100 Example 3 AA/AHPS 6:1 23.0 7,500 Example 4 AA/AHPS 6:1 15.2 4,500 Example 5 AA/AHPS 6:1 13.6 2,610 Example 6 AA/AHPS15:1 18.8 6,800 Example 7 AA/AOP 3:1 14.7 4,000 Example 8 AA/AOP 6:1 15.7 4,000 Example 9 AA/PEG AE*3:1 24.0 7,500 Example 10 AA/PEG AE** 3:1 22.6 5,100 Example 11 MAA/PEG AE** 6:1 132.0(30%) Example 12 MAA/PEG AE* 6:1 122.0(30%) Example 13 AA/GAE 3:1 18.6 Example 14 AA/GAE 6:1 22.5 Example 15 AA/AMPS4.3:1 12.7 Example 16 AA/AMPS15:1 14.4 5,200 Example 17 AA/AMPSE/AMPS 6:1:1 18.0 2,980 Example 18 AA/HPA 15:1 18.8 5,500 AA = acrylic acid AHPS = l-allyloxypropane-2-hydroxypropane-3-sulfonic acid sodium salt AOP = l-alloxy-2-propanol MAA = methacrylic acid PEG AE = polyethyleneglycol allyl ether *Q9.6 moles of ethyleneglycol **@ 4 moles of ethyleneglycol GAE = glyceryl allyl ether AMPS = 2-acrylamido-2-methylpropane sulfonic acid HPA = 2-hydroxypropyl acrylate #Mn. number average molecular weight, was measured by the gel permeation chromatography (GPC) method using Toyo Soda G-2000 SW or G-4000 SW column calibrated with polystyrene sulfonate standards in sodium nitrate solution. Molecular weight results from GPC
depend on the type of column, condition and standards used.
Example 15, 16 and 18 are disclosed in U.S. Patent 4,575,425. They are used herein to serve as a basis for comparison.

~r 1~2~3~

In addition to test~ run with the copolymers reported in ExaMples 1-18 hereof~ co~parative test~ were al80 perfor~ed u~ing mRny conventional, ~ell-known, water treatment agents. These are identified in the following ~Control Table~.
Control Table CONTROL DESCRIPTION
A - sodium tripolyphosphate 8TPP
8 - ~odium hexametaphosphate c - 2-phosphonobutane-1,2,~-tricarbo~ylic acid D - a~inotris(methylene phosphonic acid) = AMP
~ - ~ulfonated lignin F - polyacrylic acid G - copolymer of sulfonated strrene ~aleic anhydride ~AROO Chemical Co.) - copolymer malei~ anhydride~methylvinyl ether I - ~ulfonated napthalene for~aldehyde conden~ate J - copolymer of ~ulfonated ~tyrene~maleic anhydride (National Starcb Co.) ~ - ~tyrene~maleic anhydride Efficac~ Testina Calcium Oxalate Control Te~t-The dcpo~it control te~ting was basea on cry~tal modific,ation. Oxalate, depo~it control age~t, and calciu~
were respcct~vel~ adaed to a ~o~n volume of.deionized ~ter prehcated to 60C. The~ p~ of the te~t 80iution ~as checked~aa~u-ted follo~ing the addition of the de~o~it.
.. . . . .

- ~26~30 control agent; the p~ of the calciu~ sto~k solution was pread~usted to the appropriate value prior to addition.
The saople was then incubated at 60~C for one hour. At that time, the percent transmittance of the supernatant ~olution was ~easured withoS disturbing any settled precipitate. ~he ~ percent trans~ittance wa~ ~etermined at a wavelength of dlS nano~eter~.
During incubation un~odified calcium oYalate crystals settled guickly: the solution was clear and yielded a high percent tran~mittance measurement.
Crystals ~odified by the adsorption o anionic deposit control agent~ were smaller and more negatively charged and remained suspended for long period~ of tL~e; in this case the test ~olution was cloudy and yielded a lower percent transmittaAce measurement.
The percent aeposit control ~a- calculated from the e~pres~ioa.
%C - %T~untreated) - ~T~treated) ~ 100 Test Condition-: 60-C, I hour incubation time ~ 00 pp~ Ca~ae Ca~'~, 300 pp~ o~alate, 10-100 pp~ deQosit control agent, p~ 7-10 ~ e~ultr are ~eporte~ in Table~ ~IA and II8.

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1~26~31~

Table IIA
Calcium O~alate Control Te~t _ _ _ _ _ ( 60C; 10 p~ actiYe) ~ Control~
Examl?le Additive p~ 7 p0 10 PSE 91.8 9~.3 2 AA~ABPSE 92 . 8 g2 .1 3 AA/A~IPSE 85.8 - 90.6 4 AA/A~PSE 90-9 93.0 S AA/A~PSE 78 . 6 88 . 7 6 AA~A~PSE 46.~ 48.4 7 M~AOP 82.8 70.9 8 AA~AOP 70-6 71-4 9 AA~PEG AE 75 . 0 77 . 8 MJPEG AE 80-1 79.6 11 MAA~PEG AE 5~. 9 53 . 8 12 MAA~PEG AE 52.8 ~7.7 13 M~ 35-6 30.9 14 AA~GAE 67-7 63.0 AAJAMPS gO.1- 92.0 .
16 AA~AttP8 76-2 68-2 17 ~ M~ABPSEJAMPg 90.9 -95.4 18 AA~E~PA 6~.3 87.
A 0 2.2 B 22.8 15.5 C ~ 5.1 2.0 O O
E 5.6 3.1 F 4.8 25.4 G 1.0 5.3 0 1.1 J ~.C 5-2 1~ 7.5 3.7 . . A lo~er te~peratur~ tert at 25-C i8 reE?o~td il~ ~able IIB. .

:. .

~3;~

Table IIB
Calciu~ Oxalate Control ~est ~25Ç; 10 ppm aati~te) ~ Control ExamPle Additive p~ 7 P~ 10 1 AA~A~PSE 9~ .8 85.7 2 AA~A~PSE 90.8 96.1 8 M/A~PSE 9~. . 693 . 2 4 AA/AEIPSE 85.5 88.1 S AA/A~PSE 75. o 73 3 6 AA/A~PSE 66.7 63.6 7 AA/AOP 8~ .8 81.0 8 AA/AOP 85.0 90.4 - ~ 9 AA/PEG AE 88.9 90.5 U~/PEG AE 9~.. 4 85.0 1~ . MAA/PE~ AE 93.0 . 81.8 12 MAA/PEG AE 93.0 90.0 13 M/GAE 92.2 81.
1~ M/GAE 88.3 90.3 AA/AM`PS - 85.7 8~.6 16 AAJAMPS 88.9 87.2 17 AA~A~PSE~AMPS 85.7 88.6 18 AA/EPA 93.3 82.1 A 0 ~0.2 C __ __ D __ __ E ~1.7 59.5 " F 59.~ 7~,8 G 92.1 83.9 86.S 0 I 0 22.8 J 76.2 88.6 82.9 2.2 Fro~ the results reported in Tables IIA and IIB, it can be seen th t the poly~e~- in accoraan¢e ~ith the - :.

132~3~

inYention are ~uperior to the tested comparative water treat~ent agent~ in inhibiting calciu~ oxalate ~cale formation, especially at elevated temperature which i~ a more common fi~ld condition. Copolymers of E~amples 15, 16, and 18 a~ disclosed in the prior art Boffardi et al patent are al~o efficacious under the~e conditions.
Bowever, they contain either amide or ester linkages which are not as thenmally and hydrolytical1y stable as the copolymers in this invention which contain ether linkages.
The Controls and Examples previously describea were also exa~ined at 60-400 pp~ calciu~ and 100 pp~
o~alatc. The ~ control in this case wa~ de~ermined by measuring the filtered residual calcium levels since there is insuficient a~ount of crystal to be obser~ed by liqht trans~ittancc. Hith a 25 ppm acti~e of copolymer of E~a ple 3 proviaed ~2.~ and ~8.9% control, respectively.
~nder the identical condition~, duplicate te~ts ~ith a 25 pp~ acti~e of Control B material providcd 95t and ~S.6 control. ~he incon-istency in this data preclude any conclusive co pari~o~c and the data are deemed to be irrele~ant in thi~ testinq conditions. In contra~t, the resQlt~ cho~ in Ta~lea IIA and II8 are reproducible.

Calciu~ Tolerance Test Calciu~ tolerance te~ting wa~ basea on the appearance of turbidity or a deposit ~hen a deposlt control agent wa- aaded to a known concentration of calcium and incuba~ed at 60C for one hour. A deposit .
.

i32~3~

control agent was consiaered intolerant o calcium if it~
associated te~t solution was turbid or contained a sedi~ent at the end of the incubation period. ~esting results of the polymers in this in~ention and tbe co~parative ~2teri~1 are sho~n in Table III.
Test conditions: Te~p. = 60C, I hour incubation time, 400 pp~ Ca~' (as Ca ') 10-lO0 ppm deposit control agent, p~=7-10.

., , ~3~2~43~

Table III
C21ci~ Tolerance Test .
~60C; 100 pplo active~
Final Solution Appearance ExamPle _ P~ 7 P~ 10 C C

C C

11 ' C C
12 . C C

1~ C S
C C

A C D
B C T,D
C . , C D
D D D
E C C
F .~ T D
G S T
C D
Ç C
J~ C C
C ~ Clear ~ = Surb~d ,~
D e Depo~t ~ =. .

26~30 Addi~ional te~t was also done at 10 ppm activ~
for t~e copolymer~ of ~xamples 6, 13, and 1~. At p~ 7 and 10, they are all clear.

Discus~ion of Results_ana OPinion ~hereon ~ ~hown in the Tables IIA and IIB, it i8 clear that the poly~ers in the instant inventio~ control the gro~th of calciu~ oxalate cry8tal8 ~ore effectively than ~any of the conventional depo~it control agent~. In - paeticular, the poly~ers used in accordance with the invention perfor~ ~uch more effectively than the acrylic acid homopolrmer, the ~aleic anhydride copolymers, and the sulfonatea copoly~ers. ~n addition, the data in Table III
prove that the turbidity ~hich developed durinq the deeosit control test involvinq the acrylic acid~allyl ether eolymers, i~ due to calciu~ oxalate crystal gro~th ~odification, and not ~;~ply due to calciu intolerance.
In co0eariso~, se~eral of the tc8toa co~trol ~aterial~ are calciu i~toleeant. ~hesefore, the methoa~ herein aisclosed #ol~e t~e proble of coAtrolling calciu~ oxalate Eor~atio~ espe¢ially iQ aqueou~ sxste~s in ~hich high calciu~ andJor o~alate levels precl~de the use of ~ore ,co~eational agent-.

- 1~236~

Examples L9 and 20 Copoly~ees particularly useful in ac~ordance with th~
inventio~ for the inhibition of barium sulfate scale fo~mation were also pee~ared i~ accocda~ce with the procedure given in U.S.
Patent 4,659~81 (CheQ). Copolymer A however is the copolymec o~
Example ? S~ecifically, in each instance of polymer preearation, the following peocedure was used. A eeactio~ flask was equipped with a mechanical agitator, a thermo~eter, a reflux co~densec, a ~itrogen inlet and two addition inlets for the initiator and ~onomer solutions. The flask was charged with the reguired amount of deio~ized water, isoeropanol, and AHPSE (allyl hydroxy pro~yl ~ulfonate ether, 1 - allyloxy propane 2-hyd~oxy-3-sulfonic a~id, 60aium ~alt) ~onomee. The resulting ~olution wa~ then heated to 85-C under a nitroge~ blanket.
An initiator ~olution coAtaining ~odium persulEate in deionized water was seEura~^~r preEared and then sparged ~ith n~itrogen. ~he initiator solution uas theA added to the reaction flas~ along with acrylic acid o~er a perioa of three kour~. Ater this additio~, the resulting ~isture uas heated for one ~ore ~our at 85-C and ~ubsegue~tl~ the i~opropanol~ater ~olutio~ ~as stripEed off. She reaction d xture was then ccoled and neutralized by cau~tic addition. Structures of the re~ulting poly~ers ere ~erifiea by ~arbon 13 NMR.
Sable rYhercinbel~ present~ a s~marr o the pSy~ical properties o the co~oly~er~.

.. . . . . . .

- 1~2643~
g Tablc nt - Pol~mer ProPertie~
Monomer Ratio _ Vi~c08ity Example PolYmer AA~A~PsE % 8O1 ia8 Mn CP8 25~C
2 A 3:1 24.6 5,100 14.9 19 B 6:1 29.5 8,S00 28.0 ~e 25~ solids) . C 6:1 30.7 e~ooo 28-5 ~e 25% solids) AA = acrylic acia ~PSE = allyl hydrosypropyl ~ulonate ether Mn, nu~ber a~eraqe molecular ~ei~ht, ~as measurea by gel per~eation chro~atography ~G~C~ method usiog ~oyo S~da G
2000 S~ or G-4000 SW colu~n calibrated ~ith Eolystyrene ~ulfonate ~tandard~ i~ 80diw~ nitrate ~olution. Molecular ~eight re~ults fro~ GPC depena on the type o column, condition and,~tandaral~ u~ed.

.

132~3~

Efficac~ Testinn Bariu~ 8ulfate Inhibition - ~est Procedure 2 pplo E~a~a 1000 pp~ SO4,-~p~ 5.5 To lO0 g~ total test ~olution are added Ba~', polymer, and S0.~~. ~he p~ of the test 801ution i8 aa~ustea to 5.5 after the eolymer addition. She p~ of the S0,~' stock solution i8 preadju~ted to S.S prior to its addition to the tests. Tbe test solutions are heated at 60C for l hour and then cooled at roo~ temperature for 20 minutes.
Next cac~ ~olution i~ iltered through a clea~ 0.2 ~icron pore~ e filter, acidified with BCl to a final p~ of 2 and analyzed for soluble bariu~. The ~ inhibition is deter~ined by the expressions ~ Ba (treated~ - Ba (co~trol) % Inhibition ~ 100 ~ 8a ~theoretical) - Ba (control) ~ax.

Bere, ~a~' (treated) i8 the ppm soluble 8a~' resulting ron a qiveQ polyoer dosage, ~a~' Icontrol) i~ the ppm Ba~' resultiQg fro~ no treat~ent, and Ba~' (theoretical ~a~) i8 the ~oluble 8a~i intioduced into the test fro~ the :

-3~ 32~3~

sa~ stock 801ution- In this experiment, sa~' ~theoretical mRx) i8 2 ppm. Typically, Ba~' (control) i~
approxi~ately .3 pp~.
~ esulte of the barium sulfate inhibition tests are reported in Table Y .

TableV
sarium Sulfate Inhibition ~Result~ Expressed as Percent Inhibition) SSM~ SSMA+
Pol~rmer A Pol~,nDer BPol~rmer C~000 3000 -5 Pe~*23.6 25.5 24.8 0 0 2J.. 9 22.~, - 24.2 0 0 10 ppQ~21.2 2~.2 29.1 0 0 31.2 32.1 26.~ 0 0 20 pp~ 51.5 27.9 29.1 0 0 ~,8.5 36.~ -27.3 0 0 pp~ on an actives basi~
coo~erciallr avallable tyrene sulfonate~aleic anbydeide copoly~er~

In separate tests, the results were rouqhly co parable ~ith ~ell-knonA agents such as polyaceylic acid, but were ~o e~hat in~erior to po1yphosphate.
~o~ever, polyphosphate i8 not as hydrolytically stable as the polyner~ of the prese~t inveAtioA wh~ch contain ether lin~aqe~.
While thi~ iAveAtioA has been de~cribed ~ith respect to particular c~bodi~eA~ thereof, it i8 apparent that numerou~ otber for~ aAa ~odîfication~ oE this iA~ tioA dll be obvious to thosë skil~cd i;~ the art.
She a~e~ded clai-~ ~d th~ ~n~ention generally should be coA~trued to cover all ~ch obvious for~ and ~odifi~tio~ ~d~ are ~ithiQ the true ~pirit ~rt.

Claims (17)

1. A method of inhibiting the formation of calcium oxalate and/or barium sulfate scale formation in an aqueous medium having a pH of at least about 7, comprising adding to said aqueous medium an effective amount to inhibit said formation of a water soluble or water dispersible polymer having repeat units represented by the formula wherein E is the repeat unit remaining after polymerization of an .alpha.,.beta., ethylenically unsaturated compound, R, H or lower (C1-C4) alkyl, R2 is (CH2-CH2-O)mH, , monohydroxylated C2-C?
alkyl, monhydroxylated C1-C? alkylene, di- or polyhydroxy C2-C? alkyl, dihydroxy or polyhydroxy C1-C? alkylene, C1-C? alkyl, or C1-C? alkylene, n is an integer of from 1 to about 20, a is 0 or 1, X, when present, is an anionic radical selected from the group consisting of SO3, PO3, PO4, and COO, Z, when present, is H or hydrogens or a water soluble cation or cations, Z being chosen to counterbalance the valence of X, XZ combined also comprises an amine functionality of the formula wherein Fl1, F2, and F3 are independently selected from H and C1-C5 alkyl, C1-C5 hydroxy-substituted or carboxy-substituted alkyl, the molar ratios of repeat units c:d being from about 30:1 to about 1:20.

2. Method as recited in claim 1 wherein said water soluble or water dispersible polymer has a molecular weight (Mn) of from about 1,000 to 100,000.

3. Method as recited in claim 2 wherein said water soluble or water dispensible polymer has a molecular weight (Mn) of from about 1,000 to about 30,000.

4. Method as recited in claim 3 wherein said water soluble or water dispersible polymer has a molecular weight (Mn) of from about 2,500 to about 25,000.

5. Method as recited in claim 1 wherein said molar ratio of repeat units c:d is from 15:1 to 1:10.

6. Method as recited in claim I wherein E is the repeat unit obtained from the polymerization of acrylic or methacrylic acid.

7. Method as recited in claim 1 wherein R1 is H, R2 is 2-hydroxypropyl, a is 1, X=SO3, and Z is a cation or H.

8. Method as recited in claim 1 wherein R2, is H, R3 is 2-hydroxypropyl, a=0.

9. Method as recited in claim 1 wherein R1, is H, R3 is (CH2-CH2-O)mH, a = 0, n is about 1 to 15.

10. Method as recited in claim 1 wherein R1 is H, R2 is 2,3-dihydroxypropyl, a = 0.

11. Method as recited in claim 1 wherein R2 is , wherein R1 is H and n is about 1 to 15, a=0.

12. Method as recited in claim 1 wherein said aqueous system comprises a pulp or paper process system.

13. Method as recited in claim 5 wherein E is the repeat unit remaining after polymerization of (meth)acrylic acid, R1=H, R2 is monohydrosylated C1-C8 alkylene, X=SO3-2 and a=1.

14. Method as recited in claim 13 wherein R2 is 2 hydroxypropylene.

15. Method as recited in claim 14 comprising adding from about .1-500 parts of said copolymer to said aqueous system, based upon one million parts of said aqueous system.

16. Method as recited in claim 14 wherein Z is Na.

17. Method as recited in claim 1 wherein said aqueous system comprises a down hole drilling mud slurry and said method is for the inhibition of barium sulfate scale formation.