Anti-fouling and anti-corrosion protective coating method

A method of coating a surface of a metal structure in situ, which comprises the steps of applying a liquidous under coating of a modified polyvinylidene fluoride (PVDF) or polyvinylidene difluoride (PVDF) material in an air dryable solution, and then applying a liquidous over coating of a modified polyvinylidene fluoride (PVDF) or polyvinylidene difluoride (PVDF) material in an air dryable solution comprising:

• wherein the liquidous under coating solution once dried has at least the following properties:
• (a) a PVDF or a PVDF co-polymer or a combination of PVDF and PVDF copolymer to form a blend with compatible acrylic and/or other compatible polymer that is fluorinated to between about 30% to about 75% by weight excluding any solvent;
• (b) the PVDF or PVDF co-polymer or blend thereof having a molecular structure that is at least about 45% PVDF by weight when dried;
• (c) the PVDF or PVDF co-polymer having a polymer crystallinity of at least about 30% by weight;
• and
• (d) wherein the coating has a cross-hatch adhesion to metal of at least 3B when measured using the ASTM D3359 Method B scale;
• the liquidous under coating solution is made with a solvent selected from the group consisting of ketones, acetate, ester alcohol, propylene carbonate, a combination thereof, and combinations of solvents having a polarity index in the range of about 3.0 to 7.0;
• and
• wherein the liquidous over coating solution once dried has at least the following properties:
• (a) a PVDF or a PVDF co-polymer or a blend thereof that is fluorinated to between about 70% to about 100% by weight excluding any solvent;
• (b) the PVDF or PVDF co-polymer or blend thereof having a molecular structure that is at least about 75% PVDF by weight when dried;
• and
• (c) the PVDF or PVDF co-polymer having a polymer crystallinity of at least about 30% by weight;
• and
• the liquidous over coating solution is made with a solvent selected from the group consisting of ketones, acetate, ester alcohol, propylene carbonate, a combination thereof, and combinations of solvents having a polarity index in the range of about 3.0 to 7.0.