Pigmented silicone/epoxy novel blends for preparation of stratified nontoxic foul release coatings

Abstract

Incompatible polymer blends of epoxy and silicone were used for the preparation of single-coating system having anticorrosive and foul release properties by self-stratifying process. The single-coat application consists of a fixed 20 pigment volume concentration (PVC) anticorrosive bottom coat based on epoxy with a mixture of pigments like iron oxide, barytes, and zinc phosphate, and a fixed 10 PVC hydrophobic topcoat consisting of silicone resin and titanium dioxide pigment. Both the coatings were prepared separately in triple role and ball mill, respectively. Three different coating compositions were prepared by mixing silicone and epoxy coatings in different weight ratios (70:30, 80:20, and 90:10). Required amount of hardener, crosslinker, and catalyst were added to these prepared compositions separately prior to application and were thoroughly mixed and applied on mild steel and glass specimens. The prepared stratified coatings were named as STR-1, STR-2, and STR-3. The formation of self-stratification was confirmed by optical microscopy, FE-SEM, FTIR spectroscopy, and contact angle measurement. The coating systems were evaluated for adhesion, tensile strength, corrosion resistance, pseudobarnacle adhesion properties, and accumulation of foulant studies by immersion of test coupons in seawater. It is confirmed that there exists a most favorable stratified coating composition in terms of silicone and epoxy weight ratios which showed performance enhancement in terms of the hydrophobicity and foul release properties compared to other coating compositions.