Process for recycling paint flush solution

Abstract

A process for removing solids from a water-based flush solution, The process includes: providing dirty flush solution; directing the dirty flush solution to a treatment vessel; adding one or more chemicals to the treatment vessel to form a treated flush solution; separating aggregated paint compounds from the treated flush solution to form a filtered flush solution; and directing the filtered flush solution to spray application equipment. The flush system of the invention includes a treatment vessel, wherein the dirty flush solution is mixed with one or more chemicals to form a treated flush solution; a primary separation unit to remove particles including aggregated paint compounds from the treated flush solution to form a filtered flush solution; and transfer lines to direct the filtered flush solution to spray application equipment. The filtered flush solution contains: 1% to 5% by weight of a water soluble organic solvent; 0.08% to 2% by weight of an alkaline agent selected from an amine or an alkanolamine; 0.2% to 1.5% by weight of polypropylene glycol; 0.3% to 2.5% by weight of alkoxyethanol; and water.

1 - 17 . (canceled)  
     
     
         18 . A flush system for removing paint compounds from a dirty flush solution comprising: 
 a treatment vessel, wherein the dirty flush solution is mixed with one or more chemicals to form a treated flush solution;    a primary separation unit to remove particles including aggregated paint compounds from the treated flush solution to form a filtered flush solution; and    transfer lines to direct the filtered flush solution to spray application equipment.    
     
     
         19 . The system of  claim 18  further comprising a control element to monitor the PH of the treated flush solution in the treatment vessel, and direct the addition of one or more chemicals to adjust the pH of the treated flush solution.  
     
     
         20 . The system of  claim 18  further comprising a secondary separation unit to remove additional paint compounds that remain in the filtered flush solution.  
     
     
         21 . The system of  claim 18  further comprising a flush solution storage tank, wherein the flush solution storage tank holds filtered flush solution prior to contact with the spray application equipment.  
     
     
         22 . The system of  claim 18  wherein the primary separation unit is a separation unit selected from the group consisting of a microfiltration unit, a filter press, and a centrifuge  
     
     
         23 . The system of  claim 18  wherein the secondary separation unit is a separation unit selected from the group consisting of a microfiltration unit and an ultrafiltration unit.  
     
     
         24 . The system of  claim 18  wherein the one or more chemicals added to the treatment vessel is selected from the group consisting of coagulants and flocculants.  
     
     
         25 . The system of  claim 18  wherein the one or more chemicals added to the treatment vessel is an inorganic compound selected from the group consisting of magnesium oxide, aluminum sulfate, a mineral acid, aluminum hydroxide, aluminum chloride, aluminum chlorohydrate, aluminum formate, ferric chloride, ferric sulfate, and calcium chloride.  
     
     
         26 . The system of  claim 18  wherein the one or more chemicals added to the treatment vessel is an organic compound selected from the group consisting of polydimethyl diallyl ammonium chloride, polyamine epichlorohydrin-dimethylamine, and melamine formaldehyde resin colloids.  
     
     
         27 . The system of  claim 18  further comprising a collection vessel to hold dirty flush solution.  
     
     
         28 . The system of  claim 21  wherein the flush solution storage tank is used to combine filtered flush solution with fresh flush solution.  
     
     
         29 . A filtered flush solution comprising: 
 1% to 5% by weight of a water soluble organic solvent;    0.08% to 2% by weight of an alkaline agent selected from and an amine or an alkanolamine;    0.2% to 1.5% by weight of polypropylene glycol;    0.3% to 2.5% by weight of alkoxyethanol; and water.    
     
     
         30 . The filtered flush solution of  claim 29  further comprising 0.2% to 2% by weight oligomeric paint components.  
     
     
         31 . The filtered flush solution of  claim 29  wherein the water soluble organic solvent is an aromatic ethoxylate solvent of formula  
       
         
           
           
               
               
           
         
       
       wherein: R 1 , R 2 , R 3  and R 4  are independently selected from hydrogen and methyl; R 5  is hydrogen, a C 1 -C 6  alkyl, or phenyl; and n is 2, 3, 4, 5 or 6.  
     
     
         32 . The filtered flush solution of  claim 29  wherein the alkaline agent is selected from the group consisting of monoisopropanol amine, a primary amine alkoxylate, and a mixture thereof  
     
     
         33 . The filtered flush solution of  claim 29  wherein the weight ratio of alkoxyethanol:polypropylene glycol is from 4:1 to 1:2.  
     
     
         34 . The filtered flush solution of  claim 29  wherein the weight ratio of alkoxyethanol:polypropylene glycol is from 3:1 to 1:1.  
     
     
         35 . The filtered flush solution of  claim 29  wherein the weight ratio of polymeric component:polypropylene glycol is from 2:1 to 1:2.  
     
     
         36 . The filtered flush solution of  claim 29  wherein the weight ratio of alkoxyethanol:alkaline agent is from 10:1 to 2:1,  
     
     
         37 . The filtered flush solution of  claim 29  wherein the weight of alkaline agent is from 0.1% to 0.6% by weight.