Methods and devices for continuous production of polymeric dispersions

Abstract

The present invention is directed to the use of continuous extrusion devices to form high quality polymer dispersions. Screw extruder devices of the present invention inject water into a zone of high pressure, temperature, and shear to cause the rapid inversion of a weld in less than, for example, one minute, which compares very favorably with conventional batch methods, which can take, for example, two or more hours to complete an inversion. This rapid inversion—a surprising result given the extended time inversion requires in batch processes—allows for the continuous production of polymer dispersions.

1 . A method for producing a polymer dispersion in water comprising: 
 feeding into a screw extruder a thermoplastic polymer resin, a surfactant, and water;    mixing said polymer resin, said surfactant, and said water in a first zone within said screw extruder to form a weld;    moving said weld to a second zone within said screw extruder;    adding water to said weld in said second zone and mixing, thereby causing an inversion in said weld which results in the formation of said polymer dispersion in water.    
     
     
         2 . The method of  claim 1 , wherein said screw extruder is a twin screw extruder.  
     
     
         3 . The method of  claim 1 , wherein said polymer resin comprises poly(vinyl butyral).  
     
     
         4 . The method of  claim 1 , wherein said polymer resin comprises polyurethane.  
     
     
         5 . The method of  claim 1 , wherein said feeding into a screw extruder further includes a plasticizer.  
     
     
         6 . The method of  claim 1 , further comprising: 
 moving said polymer dispersion in water to a third zone within said screw extruder; and, adding water to said polymer dispersion in said third zone and mixing.    
     
     
         7 . The method of  claim 1 , wherein said second zone is maintained at a pressure of 2×10 6  Pascal to 4×10 6  Pascal and a temperature of up to 100° C.  
     
     
         8 . A method for producing a polymer dispersion in water, comprising: 
 feeding into a screw extruder a poly(vinyl butyral) resin, a surfactant, and water;    mixing said polymer resin, said surfactant, said plasticizer, and said water in a first zone within said screw extruder to form a weld;    moving said weld to a second zone within said screw extruder;    adding water to said weld in said second zone and mixing, thereby causing an inversion in said weld which results in the formation of said polymer dispersion in water.    
     
     
         9 . The method of  claim 8 , wherein said screw extruder is a twin screw extruder.  
     
     
         10 . The method of  claim 8 , further comprising: 
 moving said polymer dispersion in water to a third zone within said screw extruder; and, adding water to said polymer dispersion in said third zone and mixing.    
     
     
         11 . The method of  claim 8 , wherein said second zone is maintained at a pressure of 2×10 6  Pascal to 4×10 6  Pascal and a temperature of up to 100° C.  
     
     
         12 . A method for producing a polymer dispersion in water, comprising: 
 feeding into a screw extruder a poly(vinyl butyral) resin, a surfactant, a plasticizer, and water;    mixing said polymer resin, said surfactant, said plasticizer, and said water in a first zone within said screw extruder to form a weld;    moving said weld to a second zone within said screw extruder, wherein said second zone is maintained at a pressure of up to 2×10 6  Pascal and a temperature of up to 180° C.;    adding water to said weld in said second zone and mixing, thereby causing an inversion in said weld which results in the formation of said polymer dispersion in water; and,    moving said polymer dispersion in water to a third zone within said screw extruder; and, adding water to said polymer dispersion in said third zone and mixing.    
     
     
         13 . The method of  claim 12 , wherein said screw extruder is a twin screw extruder.  
     
     
         14 . A polymer dispersion in water made by the method comprising: 
 feeding into a screw extruder a thermoplastic polymer resin, a surfactant, and water;    mixing said polymer resin, said surfactant, and said water in a first zone within said screw extruder to form a weld;    moving said weld to a second zone within said screw extruder;    adding water to said weld in said second zone and mixing, thereby causing an inversion in said weld which results in the formation of said polymer dispersion in water.    
     
     
         15 . The polymer dispersion of  claim 14 , wherein said screw extruder is a twin screw extruder.  
     
     
         16 . The polymer dispersion of  claim 14 , wherein said polymer resin comprises poly(vinyl butyral).  
     
     
         17 . The polymer dispersion of  claim 14 , wherein said polymer resin comprises polyurethane.  
     
     
         18 . The polymer dispersion of  claim 14 , wherein said feeding into a screw extruder further includes a plasticizer.  
     
     
         19 . The polymer dispersion of  claim 14 , further comprising: 
 moving said polymer dispersion in water to a third zone within said screw extruder; and, adding water to said polymer dispersion in said third zone and mixing.    
     
     
         20 . The polymer dispersion of  claim 14 , wherein said second zone is maintained at a pressure of 2×10 6  Pascal to 4×10 6  Pascal and a temperature of up to 100° C.  
     
     
         21 . The polymer dispersion of  claim 14 , wherein said second zone comprises one or more intermediate water injection subzones.