Coating and Gas Permeation Properties of Urushiol-Based Organic/Inorganic Hybrid Films

The silica and urushiol based organic/inorganic hybrid was prepared with TEOS and urushiol by sol-gel process. GLYMO, as a silane-coupling agent, was used to obtain crack-free homogeneous films in various molar ratios, and to improve the adhesion between corona-treated BOPP substrate and the coatings. Two kinds of coating solutions were prepared; one was composed of TEOS and urushiol, the other was a mixture of TEOS, GLYMO and urushiol. Urushiol created less cracks on the film in a narrow range of molar ratios. As the amounts of urushiol were increased, the coating solutions quickly became heterogeneous. GLYMO was sufficient to prevent microcracks on the coated film and provided homogeneous coating solution. TEOS/urushiol and TEOS/GLYMO/urushiol coating solution gave insignificant effect on the permeability coefficients of oxygen, nitrogen and carbon dioxide, because the unsaturated alkyl side chain of urushiol might retard the formation of a dense structure between the inorganic silicate and the organic urushiol phase. From the antibacterial test of uncoating PP substrate and the coated film with hybrid solution, the reduction of bacteria of coating film was calculated to be 99.8%.