Protecting metal substrates from corrosion
AssigneeRaychem Corporation
InventorsGeorge Pieslak, Kathleen A. Erbes-Mrsny, Elena C. Fritchle
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Abstract
A protective coating adhered to the surface of a metal substrate such as a pipe using an adhesive composition containing an adhesive component and a polyhydroxy compound protects the substrate from corrosion. The adhesive has improved resistance to cathodic disbonding which generally weakens the adhesive bond between the protective coating and the substrate when a current is impressed through the substrate causing it to function as a cathode. The electric current inhibits loss of metal ions from the substrate to the environment thus reducing corrosion of the substrate.
Claims72
An article of a heat shrinkable material having coated on at least a part of the surface thereof an adhesive composition comprising an adhesive component and an aliphatic polyhydroxy compound in which hydroxyl groups are bonded to at least 50 percent of the aliphatic carbon atoms in an amount sufficient to impart improved resistance to cathodic disbondment to the adhesive composition, said adhesive component being a hot melt adhesive or a mastic.
A pipe having bonded to the surface thereof a polymeric coating, said coating being bonded to said pipe with an adhesive composition comprising an adhesive component and from about 0.01 to about 30 percent by weight, based on the total weight of the adhesive composition, of an aliphatic polyhydroxy compound in which hydroxyl groups are bonded to at least 50 percent of the aliphatic carbon atoms, said adhesive component being a hot melt adhesive or a mastic.
A metal pipe which is connected in an electric circuit such that said pipe forms a cathode;
- said pipe having bonded to the surface thereof a polymeric coating with an intermediate layer of an adhesive comprising an adhesive component and from about 0.01 to about 30 percent by weight, based on the total weight of the composition of an aliphatic polyhydroxy compound in which hydroxyl groups are bonded to at least 50 percent of the carbon atoms, said adhesive component being a hot melt adhesive or a mastic.
An adhesive composition comprising an ethylene-ethyl acrylate copolymer hot melt adhesive and from about 0.01 to about 30 percent by weight, based on the total weight of the adhesive composition, of an aliphatic polyhydroxy compound in which hydroxyl groups are bonded to at least 50 percent of the aliphatic carbon atoms.
An adhesive composition comprising an ethylene-vinyl acetate copolymer hot melt adhesive and from about 0.01 to about 30 percent by weight, based on the total weight of the adhesive composition, of an aliphatic polyhydroxy compound in which hydroxyl groups are bonded to at least 50 percent of the aliphatic carbon atoms.
An adhesive composition in accordance with claim 50 wherein said polyhydroxy compound is polyvinyl alcohol.
A method of improving the resistance to cathodic disbondment of an adhesive which comprises incorporating into a hot melt adhesive or a mastic from about 0.01 to about 30 percent by weight, based on the total weight of the adhesive composition, of an aliphatic polyhydroxy compound in which hydroxyl groups are bonded to at least 50 percent of the aliphatic carbon atoms.
A method of protecting a metal substrate from corrosion which comprises impressing an electrical current through said substrate such that said substrate forms a cathode, and bonding to the surface of said substrate a protective coating by means of an adhesive composition comprising an adhesive component and from about 0.01 to about 30 percent by weight, based on the total weight of the adhesive composition, of an aliphatic polyhydroxy compound in which hydroxyl groups are bonded to at least about 50 percent of the aliphatic carbon atoms, said adhesive component being a hot melt adhesive or a mastic.
Dependencies are inferred from the claim text.