Sulfonate-terminated oligomers of vinyl esters and their vinyl alcohol oligomer derivatives

Abstract

Oligomers of vinyl esters, preferably of vinyl acetate, are provided in which the molecules contain a single terminal sulfonate group, thereby making these products useful as surface-active agents. These oligomers can be converted by hydrolysis to sulfonate-terminated vinyl alcohol oligomer which is also a surface-active agent. The number average molecular weight of the vinyl ester oligomer is not over 17,000 and not over 7,500 for the vinyl alcohol oligomer. These products are made by polymerizing the vinyl ester in the presence of a bisulfite chain transfer agent in water, preferably with a cosolvent such as methanol. The vinyl ester is delay fed to the polymerization, molecular weight is controlled with the bisulfite, and the system is maintained in a virtual single phase with any organic phase present swollen with water or water and cosolvent.

1 . An oligomer of a vinyl ester of an organic acid having 2 to 18 carbon atoms, wherein the oligomer molecules are terminated at one end by a sulfonate group.  
   
   
       2 . The oligomer of  claim 1  wherein said vinyl ester is copolymerized with up to 30 mol percent of a comonomer, based on the total polymerized monomeric units in the oligomer.  
   
   
       3 . The oligomer of  claim 2  wherein said vinyl ester is vinyl acetate and said comonomer is selected from sodium vinylsulfonate, acrylic acid, diallyldimethylammonium chloride and maleic anhydride.  
   
   
       4 . The oligomer of  claim 1  wherein said vinyl ester is vinyl acetate and said oligomer is an oligomer of vinyl acetate.  
   
   
       5 . The oligomer of  claim 4  wherein a portion of the acetate units in the poly(vinyl acetate) have been hydrolyzed to hydroxy units.  
   
   
       6 . A vinyl alcohol oligomer having an average degree of polymerization not over 200 and terminated at one end by a sulfonate group.  
   
   
       7 . A method of making a sulfonate-terminated oligomer of a vinyl ester of an organic acid having 2 to 18 carbon atoms which comprises: 
 (a) forming a polymerization mixture comprising water, a vinyl ester of an organic acid having 2 to 18 carbon atoms, a free radical polymerization initiator, and a bisulfite compound chain transfer agent;    (b) subjecting said mixture to polymerization conditions for a period of time;    (c) starve feeding said vinyl ester to said mixture so that the concentration of said ester at any time during said polymerization does not exceed 3 weight percent of said mixture;    (d) maintaining said mixture under polymerization conditions of temperature and agitation for a time sufficient to polymerize said vinyl ester while maintaining the molar level of vinyl ester to bisulfite chain transfer agent in said mixture at between 20:1 and 3:1 such that the number average molecular weight of said oligomer does not exceed 2000.    
   
   
       8 . The method of  claim 7  wherein at least a portion of the polymerized product from the resultant mixture is continuously or semi-continuously removed during the reaction.  
   
   
       9 . The method of  claim 7  wherein said vinyl ester is vinyl acetate and the number average molecular weight of said oligomer is in the range of 350 to 2000.  
   
   
       10 . The method of  claim 7  wherein said mixture includes a cosolvent in addition to said water.  
   
   
       11 . The method of  claim 10  wherein the cosolvent is methanol and the ratio of water to methanol is 3:1 to 1:1 and the molar ratio of vinyl acetate to bisulfite is 5:1 to 20:1.  
   
   
       12 . The method of  claim 7  wherein said bisulfite is sodium bisulfite or ammonium bisulfite and said initiator is an oxidant component of a free radical polymerization initiator.  
   
   
       13 . The method of  claim 7  which further comprises placing under conditions suitable for hydrolysis the oligomer product of steps (a) through (d) containing polymerized units of vinyl ester, and hydrolyzing said oligomer product to convert at least a portion of said ester units in said product to alcohol units.  
   
   
       14 . A method of making a sulfonate-terminated oligomer of a vinyl ester of an organic acid having 2 to 18 carbon atoms which comprises: 
 (a) forming a polymerization mixture comprising water, a water miscible organic solvent, a vinyl ester of an organic acid having 2 to 18 carbon atoms, a free radical polymerization initiator, and a bisulfite compound chain transfer agent;    (b) subjecting said mixture to polymerization conditions for a period of time;    (c) delay feeding said water, water miscible organic solvent, vinyl ester, polymerization initiator, and bisulfite compound to said mixture in ratios such that the reacting mixture remains one phase or effectively one phase;    (d) maintaining said mixture under polymerization conditions of temperature and agitation for a time sufficient to polymerize said vinyl ester while maintaining the molar level of vinyl ester to bisulfite chain transfer agent in said mixture at between 4:1 and 60:1 such that the number average molecular weight of said oligomer does not exceed 17,000.    
   
   
       15 . The method of  claim 14  wherein at least a portion of the polymerized product from the resultant mixture is continuously or semi-continuously removed during the reaction.  
   
   
       16 . The method of  claim 14  wherein said vinyl ester is vinyl acetate and the number average molecular weight of said oligomer is in the range of 1,000 to 15,000.  
   
   
       17 . The method of  claim 14  wherein said mixture includes methanol as a cosolvent in addition to said water.  
   
   
       18 . The method of  claim 17  wherein the ratio of water to methanol is 0.25:1 to 1:1 and the molar ratio of vinyl acetate to bisulfite is 70:1 to 25:1.  
   
   
       19 . The method of  claim 14  which further comprises placing under conditions suitable for hydrolysis the oligomer product of steps (a) through (d) containing polymerized units of vinyl ester, and hydrolyzing said oligomer product to convert at least a portion of said ester units in said product to alcohol units.  
   
   
       20 . The method of  claim 19  in which a strong organic or mineral acid is used to catalyze the hydrolysis and a mixture of methanol and methyl acetate is distilled out continuously, with fresh methanol addition to maintain reaction volumes.  
   
   
       21 . The method of  claim 19  in which 40 to 99% of the ester units are converted to alcohol units.