Top Layer Coating for Improving Superhydrophobic Property of Latex Cup

摘要

A latex cup is used to collect latex from a rubber tree which is an economic plant in Thailand. The fresh latex or crude rubber consists of organic compound and water which can wet and adhere to surface of the collecting cup. In this research, surface of the latex cup was treated with polymethylhydrogen siloxane-functionalized silica compound to improve hydrophobicity so that it could repel the dirt and latex, resulting in an anti-adhesion between the latex and the cup. Surface of the latex cup was etched with 10 % v/v hydrofluoric acid for 30 min before application of the siloxane coating which was performed by immersion in the solution, painting and spraying, respectively. The result revealed that the immersion method exhibited optimum property justified by high value of water contact angle, low surface free energy, surface roughness and the field test. At the optimum polymethylhydrogen siloxane : fumed silica ratio of 3 : 1 wt%, the treated sample had water contact angle of 139.24 ± 0.78 degrees and possessed surface energy of 1.07 mJ/m2. The field test conducted in the rubber field in Trang province revealed good durability of the coating. The water contact angles were 132.15 ± 2.05 and 129.20 ± 2.34 degrees after 2 weeks and 1 month, respectively, of the field service.