Robust nontoxic antifouling elastomers

Abstract

The invention herein pertains to a method for reducing adhesion of marine organisms to a substrate and an article that is a substrate having thereon a solid coating of a fluorinated polyurethane elastomer. The elastomer is tough and has antifouling and release properties in reference to marine organisms. The method includes the steps of providing a liquid mixture of the fluorinated polyurethane elastomer, applying the elastomer mixture to said substrate, and curing the elastomer mixture to a solid coating of the fluorinated polyurethane elastomer, the elastomer having surface energy (which is a function of fluorine content) of 15-30 milli J/m 2 , Young's modulus of elasticity of 2-15 MPa, and fluorine content of 3-25%.

What is claimed:  
     
         1 . A method for reducing adhesion of marine organisms to a substrate comprising the steps of: 
 (a) providing a liquid mixture of a fluorinated polyurethane elastomer,    (b) applying the elastomer mixture to said substrate, and    (c) curing the elastomer mixture to a solid coating of the fluorinated polyurethane elastomer, the elastomer having surface energy of 15-30 milli J/m 2 , Young's modulus of elasticity of 2-15 MPa, and fluorine content of 3-25%.    
     
     
         2 . The method of  claim 1  wherein surface energy of the elastomer is 20-29 mJ/m 2 , its Young's modulus of elasticity is 2-10 MPa and its fluorine content is 6-18%.  
     
     
         3 . The method of  claim 1  wherein surface energy of the elastomer is 25-27 mJ/m 2  and its Young's modulus of elasticity is 3-7 MPa, and its fluorine content is 9-10%.  
     
     
         4 . The method of  claim 1  wherein the elastomer is a reaction product of a base component comprising a polyol, or a mixture thereof, with a curing agent containing a diisocyanate, or a mixture thereof, the base component contains a mixture of at least one diol and at least one triol.  
     
     
         5 . The method of  claim 4  wherein the ratio of the NCO/OH groups in the curing agent and the base component is below 2.  
     
     
         6 . The method of  claim 4  wherein the NCO/OH ratio in the curing agent and the base component is 1-1.8 and amount of trifunctional OH is 18-32 mol percent.  
     
     
         7 . The method of  claim 4  wherein the NCO/OH ratio in the curing agent and the base component is 1-1.5 and amount of trifunctional OH is 23-27 mol percent.  
     
     
         8 . The method of  claim 6  wherein the elastomer is nontoxic to marine organisms, contains no fugitive ingredients, is partially cross-linked and is in the form of a pourable liquid, before curing, that has a working life of 15 minutes to 8 hours.  
     
     
         9 . The method of  claim 8  wherein the substrate has a coating of a primer thereon onto which the elastomer is applied.  
     
     
         10 . The method of  claim 9  wherein the base component includes a metal salt catalyst.  
     
     
         11 . The method of  claim 9  wherein the base component is in a solvent solution, contains a mixture of at least one diol and trimethylol propane propoxylate, and a metal salt catalyst.  
     
     
         12 . The method of  claim 11  wherein the curing agent includes a diisocyanate prepolymer and poly(propylene glycol) terminated with toluene-2,4-diisocyanate.  
     
     
         13 . An article comprising a substrate and a rubbery fluorinated polyurethane elastomer in dry form adhering to said substrate, said elastomer is a reaction product of a base component containing a polyol, or a mixture thereof, and a curing agent containing a diisocyanate, or a mixture thereof, said elastomer is nontoxic to marine organisms and has surface energy of 15-30 milli J/m 2 , Young's modulus of elasticity of less than about 2-15 Mpa, and fluorine content of 3-25%, so that it has sufficient antifouling and release properties with respect to marine organisms and sufficient toughness to serve as a coating on the substrate.  
     
     
         14 . The article of  claim 13  wherein said elastomer is partially cross-linked and its surface energy is 20-29 mJ/m 2 , its Young's modulus of elasticity is 2-10 MPa, and its fluorine content is 6-18%.  
     
     
         15 . The article of  claim 13  wherein surface energy of said elastomer is 25-27 mJ/m 2 , its Young's modulus of elasticity is 3-7 Mpa, and its fluorine content is 9-10%.  
     
     
         16 . The article of  claim 14  wherein some OH groups in said elastomer remain unreacted so the full cross-linking in said elastomer is avoided.  
     
     
         17 . The article of  claim 16  wherein said elastomer has release property that enables at least majority of accumulated marine organisms on its surface to be removed by hosing or movement of said elastomer through water at speed of a water craft.  
     
     
         18 . The article of  claim 17  wherein said substrate is metal having a primer coating on which said elastomer is disposed.  
     
     
         19 . The article of  claim 18  wherein said primer coating is epoxy polyamide and thickness of said elastomer is 500-6250 microns, said elastomer is nontoxdicto marine organisms and contains no fugitive ingredients.