Coating Based on Cashew Nut Shell Liquid Resin Kampon Keetasombat, Dr. Theeraphan Machan, Dr. Uraiwan Intatha, Nattakan Soykeabkaew * School of Science, Mae Fah Luang University, Chiang Rai 57110, Thailand * E-Mail: nattakan@mfu.ac.th, Tel. +66 5391 6774, Fax. +66 5391 6776 Abstract Cashew nut shell liquid (CNSL) is the waste from cashew nut snack industry. CNSL is a dark brown liquid and can be extracted by Soxhlet extraction method using methanol and hexane as the solvents. However, using methanol solvent in extraction methanol has higher yield and density than hexane solvent. The CNSL composes of phenolic compound. In crosslink process, CNSL can be crosslinked with formaldehyde using Resole reaction. For coating application, CNSL was mixed with formaldehyde, sodium hydroxide and then coated on the surface of wood specimens. The water resistance of CNSL-coated wood was studied. It was found that coated wood had low moisture and water absorption. Key words: Cashew nut shell liquid (CNSL), Coating, Water resistance Introduction Now the thermoset and thermoplastic were produced from petroleum. The petroleum is a limited resource and intensely decline (Kathalewar et al., 2014). The major sources of thermoset and thermoplastic are from renewable resources. The renewable resources were made from product or by product of agricultural. Thailand is agricultural countries, and the majority of people are farmers. Cashew nut shell is by product from cashew nut snack industry. It can be extracted to yield cashew nut shell liquid, the liquid is dark brown color and it can be converted into coating material. Cashew nut shell liquid composes of phenol structure, it is called phenolic compound and it can be crosslinked with formaldehyde by resole reaction. The most coating materials were made from petroleum and it was part in thermoset. Cashew nut shells liquid replace coating material from petroleum and has better water resistant property. Methodology Extraction Cashew nut shell (CNS) was ground and extracted by a soxhlet method using 500 ml of solvent (MeOH or hexane) at 70 °C for 24 h. After that, the extracted liquid was heated by the rota evaporation machine at temperature of 60-70 °C for 4 h. to remove the remaining solvent from the CNSL. The percentage of yield and density of CNSL were determined by following equations: Gram of CNSL (from extraction) × 100 (2.1) Gram of CNSL paste (initial) Yield (%) =