Stripping agent for chemically resistant coatings

Abstract

A low viscosity, non-foaming stripping composition comprising by volume 79%-methylpyrrolidone, 20% monoethanolamine and 1% non-ionic surface active agent is applied at elevated temperatures (around 180 degrees F.) for removing thick (e.g., 10-mil) epoxy coatings and similar chemically resistant coatings from steel surfaces, and is suitable for spray application and for recycling.

What is claimed is: 
     
       1. A low viscosity stripping composition, suitable for application by spraying at elevated temperatures, for the removal of chemically resistant coatings, the mixture comprising: (a) 79 percent by volume of N-methylpyrrolidone;   (b) 20 percent by volume of ethanolamine; and   (c) 1 percent by volume of a non-ionic surface active agent for increasing penetration of the coating and without producing foam during spraying.   
     
     
       2. A stripping composition as in claim 1 wherein the surface active agent is a non-ionic detergent having high resistance to the alkaline environment caused by ethanolamine in the stripping composition. 
     
     
       3. A stripping composition as in claim 1 wherein the temperature at which said stripping composition is to be applied to chemical resistant coatings to be removed is at a range of 170 to 190 degrees F. 
     
     
       4. A stripping composition as in claim 3 wherein the preferred temperature is 180 degrees F. 
     
     
       5. The method for removing chemically resistant coatings from walls of bilges and tanks, comprising: (a) spraying the chemically resistant coatings within said bilges and tanks with a stripping composition comprised by volume of approximately 79 percent N-methylpyrrolidone, 20 percent ethanolamine, and 1 percent of a non-ionic surface active agent;   (b) said stripping composition being applied by spraying onto said chemically resistant coatings to be removed at a temperature range of 170 to 190 degrees F.;   (c) removing the used said stripping composition along with removed coating material for recycling of the stripping composition.   
     
     
       6. A method as in claim 5 wherein said non-ionic surface active agent is a non-ionic detergent having high resistance to the alkaline environment caused by said ethanolamine in the stripping composition and not producing foam during spraying. 
     
     
       7. A method as in claim 5 wherein said non-ionic surface active agent is chosen to increase penetration and undercutting of the coating to be removed, and to have high resistance to degradation in an alkaline environment while not producing foam during spraying. 
     
     
       8. A method as in claim 5 wherein the stripping composition is applied to the coating at a preferred temperature of 180 degrees F. 
     
     
       9. A method as in claim 5 wherein the ingredients of said stripping composition are recovered by distillation. 
     
     
       10. A method as in claim 5 wherein said stripping composition is sprayed onto chemical resistant coatings to be removed at a pressure range of approximately 50 to 100 psi or greater. 
     
     
       11. A method as in claim 10 wherein a preferred rate of application of said stripping composition in tanks is 50 gpm. 
     
     
       12. A low viscosity stripping composition, suitable for application by spraying at elevated temperatures, for the removal of chemically resistant coatings, the mixture comprising: (a) 77 to 80 percent by volume of N-methylpyrrolidone;   (b) 19 to 22 percent by volume of ethanolamine; and   (c) 1 percent by volume of a non-ionic surface active agent for increasing penetration of the coating to be removed without producing foam during spraying.   
     
     
       13. A stripping composition as in claim 12 wherein the surface active agent is a non-ionic detergent having high resistance to the alkaline environment caused by ethanolamine in the stripping composition. 
     
     
       14. A stripping composition as in claim 12 wherein the temperature at which said stripping composition is to be applied to chemical resistant coatings to be removed is at a range of 170 to 190 degrees F. 
     
     
       15. A stripping composition as in claim 12 wherein the preferred temperature is 180 degrees F. 
     
     
       16. The method for removing chemically resistant coatings from walls of bilges and tanks, comprising: (a) spraying the chemically resistant coatings within said bilges and tanks with a stripping composition comprised by volume of approximately 77 to 80 percent N-methylpyrrolidone, 19 to 22 percent ethanolamine, and 1 percent of a non-ionic surface active agent;   (b) said stripping composition being applied by spraying onto said chemically resistant coatings to be removed at a temperature range of 170 to 190 degrees F.;   (c) removing the used said stripping composition along with removed coating material for recycling of the stripping composition.   
     
     
       17. A method as in claim 16 wherein said non-ionic surface active agent is chosen to increase penetration and undercutting of the coating to be removed, and have high resistance to degradation in the alkaline environment caused by the ethanolamine in the stripping composition while not producing foam during spraying. 
     
     
       18. A method as in claim 16 wherein the stripping composition is applied to the coating at a preferred temperature of 180 degrees F. 
     
     
       19. A method as in claim 16 wherein the ingredients of said stripping composition are recovered by distillation following removal of removed coating material. 
     
     
       20. A method as in claim 16 wherein said stripping composition is sprayed onto chemical resistant coatings to be removed at a pressure range of approximately 50 to 100 psi or greater. 
     
     
       21. A method as in claim 16 wherein said non-ionic surface active agent consists of nonylphenol reacted with 9 miles of ethylene oxide.