Thixotropic dispersions of polysuccinimide and their use

Abstract

The present invention relates to stable thixotropic polysuccinimide (PSI) dispersions, known as slurries, and to their use as additives for improving the flow properties of concrete, in oil wells, in acidic gel cleaners, and in drainage systems of tunnel constructions.

What is claimed is:  
     
         1 . A stable thixotropic dispersion comprising polysuccinimide in a protic solvent.  
     
     
         2 . The dispersions according to  claim 1 , wherein the dispersion comprises a hydrocolloid.  
     
     
         3 . The dispersion according to  claim 2 , wherein the dispersion further comprises an anionic or nonionic surfactant.  
     
     
         4 . The dispersion according to  claim 1 , wherein the protic solvent is water.  
     
     
         5 . The dispersion according to  claim 2 , wherein the surfactant is a fatty alcohol ethoxylate.  
     
     
         6 . The dispersion according to  claim 1 , wherein the dispersion contains from about 10 to about 90% by weight of polysuccinimide and from about 0.01 to about 20% by weight of a surfactant.  
     
     
         7 . The dispersion according to  claim 1 , wherein the dispersion further comprises biodegradable thickeners.  
     
     
         8 . A process for preparing a thixotropic polysuccinimide dispersion comprising: 
 (a) introducing polysuccinimide and/or its copolymers to a vessel,    (b) adding a protic solvent and surfactant to the vessel and mixing, thereby forming a mixture,    (c) thoroughly mixing the mixture, thereby forming a homogeneous dispersion, and    (d) solidifying the homogeneous dispersion.    
     
     
         9 . A cement composition or a concrete composition comprising a flow-property-improving fraction of a thixotropic polysuccinimide dispersion.  
     
     
         10 . An acidic gel cleaner composition comprising a flow-property-improving fraction of a thixotropic polysuccinimide dispersion.