Powder dispersant for hydraulic compositions

Abstract

The present invention provides a powdery dispersant for hydraulic compositions, which is excellent in pumping before drying and in pressure resistance and humidity resistance, which comprises one or more copolymers obtained by polymerizing a specific vinyl monomer (a) such as an ethylenically unsaturated carboxylic acid derivative having a polyoxyalkylene group with a specific vinyl monomer (b) such as (meth)acrylic acid etc., wherein the average number of C 2-4 oxyalkylene groups or oxystyrene groups added is 45 to 150, (a)/[(a)+(b)]×100 ranges from 15 to 45 (mole-%), and at least a part of the copolymers are monovalent or polyvalent metal salts.

What is claimed is:  
     
         1 . A powdery dispersant for a hydraulic composition, which comprises at least one copolymer obtainable by polymerizing at least one vinyl monomer (a) represented by the formula (1):  
       
         
           
           
               
               
           
         
         wherein R 1  and R 2  represent a hydrogen atom or a methyl group, R 3  represents a hydrogen atom or —COO(AO) n X, m is a number of 0 to 2, p is a number of 0 or 1, AO represents a C 2-4  oxyalkylene group or an oxystyrene group, n is the average mole number and is a number of 2 to 300 and X represents a hydrogen atom or a C 1-18  alkyl group;  
         with at least one vinyl monomer (b) represented by the formula (2):  
         
           
             
             
                 
                 
             
           
         
         wherein R 4 , R 5  and R 6  are the same as or different from one another and each represent a hydrogen atom, a methyl group or —(CH 2 ) m1 COOM 2  in which —(CH 2 ) m1 COOM 2  may be combined with —COOM 1  or another —(CH 2 ) m1 COOM 2  to produce an anhydride, M 1  and M 2  of these groups not being present, M 1  and M 2  represent a hydrogen atom or a polyvalent metal and m, is a number of 0 to 2,  
         in which the average mole number of C 2-4  oxyalkylene groups or oxystyrene groups added to the dispersant molecule is 45 to 150, (a)/[(a)+(b)]×100 ranges from 15 to 45 (mole %) and at least part of the copolymer is a polyvalent metal salt.  
       
     
     
         2 . The powdery dispersant according to  claim 1 , wherein (a)/[(a)+(b)]×100 ranges from 20 to 35 mole %.  
     
     
         3 . A powdery dispersant for a hydraulic compositions, which comprises at least one copolymer obtained by polymerizing at least one vinyl monomer (a) represented by the formula (1):  
       
         
           
           
               
               
           
         
         wherein R 1  and R 2  represent a hydrogen atom or a methyl group, R 3  represents a hydrogen atom or —COO(AO) n X, m is a number of 0 to 2, p is a number of 0 or 1, AO represents a C 2-4  oxyalkylene group or an oxystyrene group, n is the average mole number of added groups and is a number of 2 to 300 and X represents a hydrogen atom or a C 1-18  alkyl group;  
         with at least one vinyl monomer (b) represented by the formula (2):  
         
           
             
             
                 
                 
             
           
         
          wherein R 4 , R 5  and R 6  are the same as or different from one another and each represent a hydrogen atom, a methyl group or —(CH 2 ) m1 COOM 2  in which —(CH 2 ) m1 COOM 2  may be combined with —COOM 1  or another —(CH 2 ) m1 COOM 2  to produce an anhydride, M 1  and M 2  of these groups not being present, M 1  and M 2  represent a hydrogen atom or a monovalent metal and m, is a number of 0 to 2, in which the average mole number of C 2-4  oxyalkylene groups or oxystyrene groups added to the dispersant molecule is 50 to 150, (a)/[(a)+(b)]×100 ranges from 15 to 45 (mole %) and at least part of the copolymers is a monovalent metal salt.  
       
     
     
         4 . The powdery dispersant according to  claim 3 , wherein (a)/[(a)+(b)]×100 ranges from 20 to 45 mole %.  
     
     
         5 . The powdery dispersant according to  claim 1  or  3 , wherein the average mole number of C 2-4  oxyalkylene groups or oxystyrene groups added is 60 to 130.  
     
     
         6 . The powdery dispersant according to  claim 1  or  3 , wherein the average mole number of C 2-4  oxyalkylene groups or oxystyrene groups added is 60 to 115.  
     
     
         7 . The powdery dispersant according to  claim 1 , wherein all the copolymers are polyvalent metal salts in part.  
     
     
         8 . The powdery dispersant according to  claim 1  or  3 , which comprises a copolymer obtained from starting monomers containing 98 to 100% by weight of the monomers (a) and (b).  
     
     
         9 . The powdery dispersant according to  claim 1  or  3 , which comprises 50 to 100% by weight of dispersant particles whose diameter is 500 Mm or less.  
     
     
         10 . A hydraulic composition comprising the powdery dispersant described in  claim 1  or  3  and a hydraulic composition.  
     
     
         11 . Use of the powdery dispersant described in  claim 1  or  3  as a dispersant for a hydraulic composition.  
     
     
         12 . A method of dispersing a hydraulic composition by the powdery dispersant described in  claim 1  or  3 .