Setting retarder for hydrate-forming binders

Abstract

A setting retarder for hydrate-forming binders is produced by reacting a first reactant A, including an amino acid and/or an amino acid derivative, with a second reactant C, including an amine-free carboxylic acid and/or an amine-free carboxylic acid derivative, in a reaction mixture to form a reaction product, the reaction mixture further containing at least one base, and alternatingly adding partial quantities of the at least one base and partial quantities of the second reactant C to the reaction mixture so that the reaction is carried out at a pH value in a range of from 7.5-11.5, wherein the setting retarder is in liquid or solid form.

1 . A setting retarder for hydrate-forming binders produced by a method comprising:
 reacting a first reactant A, comprising an amino acid and/or an amino acid derivative, with a second reactant C, comprising an amine-free carboxylic acid and/or an amine-free carboxylic acid derivative, in a reaction mixture to form a reaction product, the reaction mixture further containing at least one base; and   alternatingly adding partial quantities of the at least one base and partial quantities of the second reactant C to the reaction mixture so that the reaction is carried out at a pH value in a range of from 7.5-11.5,   wherein the setting retarder is in liquid or solid form.   
     
     
         2 . The setting retarder according to  claim 1 , wherein the first reactant A comprises an amino acid, and the amino acid is lysine and/or thereonine. 
     
     
         3 . The setting retarder according to  claim 1 , wherein the second reactant C comprises an amine-free carboxylic acid derivative. 
     
     
         4 . The setting retarder according to  claim 3 , wherein the amine-free carboxylic acid derivative is a carboxylic acid anhydride. 
     
     
         5 . The setting retarder according to  claim 1 , wherein the first reactant A and the second reactant C are reacted to form an amide. 
     
     
         6 . The setting retarder according to  claim 1 , wherein the reaction is carried out at a temperature in a range of from 20-60° C. 
     
     
         7 . The setting retarder according to  claim 1 , wherein the base comprises at least one member selected from the group consisting of alkali hydroxides, earth alkali hydroxides and earth alkali oxides. 
     
     
         8 . The setting retarder according to  claim 1 , the method further comprising first preparing an aqueous solution of the reactant A, and then setting the pH range of the reaction mixture to the range of from 7.5-11.5 by adding the at least one base to the reaction mixture. 
     
     
         9 . The setting retarder according to  claim 1 , the method further comprising drying the reaction mixture. 
     
     
         10 . The setting retarder according to  claim 1 , wherein the pH value of the reaction mixture is held constant within the range of from 7.5-11.5 during the reaction. 
     
     
         11 . The setting retarder according to  claim 4 , wherein the carboxylic acid anhydride is succinic acid anhydride. 
     
     
         12 . The setting retarder according to  claim 7 , wherein the base comprises at least one member selected from the group consisting of NaOH, KOH, CaO and Ca(OH) 2 . 
     
     
         13 . A binder composition comprising:
 the setting retarder according to  claim 1 ; and   a hydrate-forming binder.   
     
     
         14 . A molded body produced by a method comprising:
 mixing the binder composition according to  claim 13  with water; and then hardening the mixed composition.   
     
     
         15 . A method of delaying a start of setting of hydrate-forming binders, comprising:
 adding the setting retarder according to  claim 1  to the hydrate-forming binders.