Roofing repair system and method

Abstract

A roofing repair system including a multi-part primer and a water-activated overcoat composition. The multi-part primer includes a first part including a hydroxyl-functional (meth)acrylic (co)polymer, and a second part including a mixture of a hydrophilic polyfunctional aliphatic polyisocyanate and a hydrophobic polyfunctional aliphatic polyisocyanate, wherein a molar ratio of hydroxyl functionality in the first part to isocyanate functionality in the second part is less than 1. The water-activated overcoat composition includes at least one compound selected from polyketimines having amino groups attached to secondary carbon atoms, polyenamines, and oxazolidines. In some exemplary embodiments, the volume ratio of the multi-part primer to the water-activated composition is from 5:1 to 7:1. In certain exemplary embodiments, the multi-part primer is substantially free of organic solvents. A method of using the roofing repair system to repair the weathered surface of an elastomeric roofing membrane is also described.

1 . A roofing repair system comprising:
 (a) a multi-part primer comprising a first part including a hydroxyl-functional (meth)acrylic polymer, and a second part including a mixture of a hydrophilic polyfunctional aliphatic polyisocyanate and a hydrophobic polyfunctional aliphatic polyisocyanate, wherein a molar ratio of hydroxyl functionality in the first part to isocyanate functionality in the second part is less than 1; and   (b) a water-activated overcoat composition comprising at least one compound selected from polyketimines having amino groups attached to secondary carbon atoms, polyenamines, and oxazolidines.   
     
     
         2 . The roofing repair system of  claim 1 , wherein a volume ratio of the multi-part primer to the water-activated overcoat composition is from 5:1 to 7:1. 
     
     
         3 . The roofing repair system of  claim 1 , wherein the multi-part primer is substantially free of organic solvents. 
     
     
         4 . The roofing repair system of  claim 1 , wherein the first part of the multi-part primer further comprises water. 
     
     
         5 . The roofing repair system of  claim 1 , wherein the multi-part primer further comprises a catalyst, a biocide, a surfactant, a dispersant, a rheology modifier, a particulate filler, a fibrous material, a defoamer, a plasticizer, or a combination thereof. 
     
     
         6 . The roofing repair system of  claim 1 , wherein the hydroxyl-functional (meth)acrylic (co)polymer comprises dispersed particles. 
     
     
         7 . The roofing repair system of  claim 1 , wherein the hydroxyl-functional (meth)acrylic (co)polymer comprises from 30 to 50% by weight of the first part of the multi-part primer. 
     
     
         8 . The roofing repair system of  claim 1 , wherein a weight ratio of hydrophilic polyfunctional aliphatic polyisocyanate to hydrophobic polyfunctional aliphatic polyisocyanate in the second part of the multi-part primer is at least 1:1. 
     
     
         9 . The roofing repair system of  claim 8 , wherein the combined weight of hydrophilic polyfunctional aliphatic polyisocyanate and hydrophobic polyfunctional aliphatic polyisocyanate comprises at least 80% by weight of the second part. 
     
     
         10 . The roofing repair system of  claim 1 , wherein the water-activated overcoat composition further comprises a film-forming thermoplastic polymer. 
     
     
         11 . The roofing repair system of  claim 1 , wherein the film-forming thermoplastic polymer comprises a polyurethane segment. 
     
     
         12 . The roofing repair system of  claim 1 , wherein the water-activated overcoat composition further comprises a urethane prepolymer comprising an isocyanate which has been blocked with a phenol or an oxime. 
     
     
         13 . The roofing repair system of  claim 1 , further comprising a reinforcing layer. 
     
     
         14 . The roofing repair system of  claim 13 , wherein the reinforcing layer comprises a fiberglass mesh, a polyester fiber mesh, an ethylene-propylene dimer elastomer, a chlorinated polyethylene elastomer, a chlorosulfonated polyethylene elastomer, an acrylonitrile rubber, a poly(isoburylene) elastomer, a thermoplastic polyolefin elastomer, a polyvinyl chloride elastomer, or a combination thereof. 
     
     
         15 . The roofing repair system of  claim 1 , further comprising an applicator selected from a brush, a pad, a squeegee, a roller, a sprayer, or a combination thereof. 
     
     
         16 . A method of repairing a roof, comprising the steps of:
 (a) mixing together a first part comprising a hydroxyl-functional (meth)acrylic polymer and a second part comprising a mixture of hydrophilic polyfunctional aliphatic polyisocyanate and a hydrophobic polyfunctional aliphatic polyisocyanate, wherein a molar ration of hydroxyl functionality in the first part to isocyanate functionality in the second part is less than 1, to obtain an activated primer mixture;   (b) applying the activated primer mixture to a weathered surface of an elastomeric roofing membrane; and   (c) applying the water-activated overcoat composition to the primer mixture on the weathered surface of the elastomeric membrane, wherein the water-activated overcoat composition comprises at least one compound selected from polyketimines having amino groups attached to secondary carbon atoms, polyenamines, and oxazolidines.   
     
     
         17 . The method of  claim 16 , wherein the activated primer mixture comprises water in an amount sufficient to obtain a non-volatile solids content of from 30% to 50% by volume of the activated primer mixture. 
     
     
         18 . The method of  claim 16 , wherein step (b) is completed within two hours after beginning step (a). 
     
     
         19 . The method of  claim 18 , wherein step (c) is begun at least two hours after step (b) is completed, and step (c) is completed no more than 168 hours after beginning step (a). 
     
     
         20 . The method of  claim 16 , wherein the elastomeric roofing membrane comprises ethylene-propylene dimer elastomer, chlorinated polyethylene elastomer, chlorosulfonated polyethylene elastomer, acrylonitrile rubber, poly(isobutylene) elastomer, thermoplastic polyolefin elastomer, polyvinyl chloride elastomer, or a combination thereof.