Method of controlling carbonate scale in aqueous systems

Abstract

A method of inhibiting carbonate scale in an industrial water system includes the steps of dosing the industrial water system with a water treatment polymer comprising at least 60 mol % of carboxylic acid monomer and a quaternized naphthalimide fluorescent monomer as disclosed herein, and then monitoring the fluorescence of the water system. If both maleic acid and phosphino moieties are included in the water treatment polymer, then the maleic acid is present as no greater than 70 mol % of the water treatment polymer. If the polymer contains a sulfonic acid monomer, the polymer is a fluorescence efficient polymer.

1 . A water treatment polymer formed from a polymerization mixture comprising:
 (i) at least one water-soluble carboxylic acid monomer, or salt or anhydride thereof, present in an amount of 60-99.999 mol % based on 100 mol % of the polymer;   (ii) at least one quarternized naphthalimide fluorescent monomer of either Structure (I) or Structure (II) wherein:   Structure (I) is:   
       
         
           
           
               
               
           
         
         wherein 
         R 4  and R 41  are independently selected from H, hydroxy, alkoxy, aryloxy, arylalkoxy, alkylaryloxy, (meth)allyloxy, vinylbenzyloxy, heteroaryl, —NO 2 , C 1 -C 4 alk-O—(CHR 5 CH 2 O—) n , —CO 2 H or a salt thereof, —SO 3 H or a salt thereof, —PO 3 H 2  or a salt thereof, -alkylene-CO 2 H or a salt thereof, -alkylene-SO 3 H or a salt thereof, and -alkylene-PO 3 H 2  or a salt thereof; 
         n=1-10; 
         R 1  and R 2  are independently C 1 -C 4 alkyl; 
         R 3  is selected from (meth)allyl, (meth)acryl, 2-hydroxy-3-(meth)allyloxypropyl, 1-hydroxy-3-(meth)allyloxypropyl, vinylbenzyl, 3-(meth)acrylamidopropyl, and 2-(meth)acryloyloxy ethyl, or alkyl; 
         R 5  is selected from H and C 1 -C 4 alkyl; 
         A is selected from the group consisting of alkyl, alkoxyalkyl, alkylamidoalkyl, arylalkyl or nonexistent; with the proviso that when A is nonexistent, B is nitrogen and B is bonded directly to the imide nitrogen; 
         B is sulfur or nitrogen with the proviso that when B is sulfur only one of R 1  or R 2  is present; and 
         X is an anionic counter ion; 
         Structure (II) is: 
       
       
         
           
           
               
               
           
         
         wherein 
         m=1-10; 
         R 7  and R 8  and R 9  are each independently an alkyl and may be the same or different; 
         R 6  is selected from the group consisting of vinyl, alkenyl, and (meth)allyl; 
         D is oxygen or nonexistent, with the proviso that when D is nonexistent, (CH 2 ) m  is bonded directly to a carbon on the ring; and 
         X is an anionic counter ion; 
         said quaternized naphthalimide fluorescent monomer being present in said water treatment polymer in an amount of 0.001-10 mol % based on 100 mol % of the water treatment polymer and being free of ester moieties; 
         with the proviso that if the polymer contains a phosphorous moiety that is a phosphino group and at least part of the carboxylic acid is maleic acid or a salt or anhydride thereof, then the maleic acid, salt or anhydride thereof is not greater than 70 mol % of the polymer; and 
         with the proviso that if the polymer contains a sulfonic acid monomer, the polymer is fluorescence optimized. 
       
     
     
         2 . The polymer of  claim 1 , wherein the polymerization mixture includes at least one monomer of Structure (I) comprising less than 8 mol %, based on 100 mol % of Structure (I), of Structure (III) 
       
         
           
           
               
               
           
         
         wherein A, B, R 1 , R 2 , are as defined in  claim 1  and R 4  and R 41  are independently selected from H, hydroxy, alkoxy, aryloxy, arylalkoxy, alkylaryloxy, heteroaryl, —NO 2 , C 1 -C 4 alk-O—(CHR 5 CH 2 O—) n , —CO 2 H or a salt thereof, —SO 3 H or a salt thereof, —PO 3 H 2  or a salt thereof, -alkylene-CO 2 H or a salt thereof, -alkylene-SO 3 H or a salt thereof, and -alkylene-PO 3 H 2  or a salt thereof. 
       
     
     
         3 . The polymer of  claim 1 , which contains a quarternized naphthalimide fluorescent monomer of Structure (I), wherein R 4  is selected from alkoxy, alkoxyamine, alkyl, aryl, alkaryl, or C 1 -C 4 alk-O—(CHR 5 CH 2 O—) n , and R 41  is H, the polymer containing less than 8 mole % of fluorescent monomers of Structure (IV) 
       
         
           
           
               
               
           
         
         where R 42  is halogen. 
       
     
     
         4 . The polymer of  claim 1 , wherein R 4  is alkoxy selected from methoxy, ethoxy, propyloxy, isopropyloxy, n-butoxy, isobutoxy, and tert-butoxy, and R 41  is H. 
     
     
         5 . The polymer of  claim 1 , wherein R 4  and R 41  are both alkoxy selected from methoxy, ethoxy, propyloxy, isopropyloxy, n-butoxy, isobutoxy, and tert-butoxy. 
     
     
         6 . The polymer of  claim 1 , which comprises a mixture of monomers of Structure (I) wherein in at least one of said monomers R 4  and R 41  are both H or alkyl; and in at least one other of said monomers R 4  and R 41  are both alkoxy. 
     
     
         7 . The polymer of  claim 1 , wherein the polymerization mixture contains at least one monomer of Structure (II) comprising less than 8 mol %, based on 100 mol % of Structure (II), of Structure (VI) 
       
         
           
           
               
               
           
         
         wherein D, m, R 7 -R 9 , and X −  are as defined in  claim 1  and R 66  is H or alkyl. 
       
     
     
         8 . The polymer of  claim 1 , wherein the polymer contains a quarternized naphthalimide fluorescent monomer of Structure (II), D is oxygen, and the polymer contains less than 8 mol % of fluorescent monomers of Structure (V) 
       
         
           
           
               
               
           
         
         where R 42  is halogen. 
       
     
     
         9 . The polymer according to  claim 1 , which is substantially free of ammonium or amine salts. 
     
     
         10 . The polymer according to  claim 1 , which provides carbonate inhibition of at least 90% when dosed at no greater than 20 ppm to a water system having a Langelier Saturation Index (LSI) of 2. 
     
     
         11 . The polymer according to  claim 1 , which provides carbonate inhibition of at least 90% when dosed at no greater than 20 ppm to a water system having a LSI of 2.5. 
     
     
         12 . The polymer according to  claim 1 , which is capable of maintaining hypochlorite bleach at pH 9. 
     
     
         13 . The polymer according to  claim 1 , wherein the fluorescent monomer is incorporated into the polymer to an extent of at least 90%. 
     
     
         14 . A method of controlling carbonate scale in a water system, the method comprising the steps of:
 (a) dosing the water system with a water treatment polymer according to  claim 1 ; and   (b) monitoring the fluorescent signal emitted from said industrial water system.   
     
     
         15 . A process of preparing the water treatment polymer according to  claim 1 , the process comprising the step of polymerizing a polymerization mixture comprising:
 (i) at least one water-soluble carboxylic acid monomer, or salt or anhydride thereof, present in an amount of 60-99.999 mol %;   (ii) at least one quarternized naphthalimide fluorescent monomer of either Structure (I) or (II);   wherein the quarternized fluorescent naphthalimide monomer is either (a) dosed to the polymerization process by itself or (b) premixed with the water-soluble carboxylic acid monomer or other monomer to form a premixture, which is then added to the polymerization process.