▎ 摘　　要

NOVELTY - Manufacture of buoy involves forming (i) a hemisphere in a hemispherical shape by coating a protective layer to prevent corrosion of the inner wall surface of the hemisphere and to increase durability, (ii) injecting a pressure-increasing material into the molded hemisphere, and (iii) joining the two hemispheres to one another by thermal fusion method. The protective coating layer comprises a mixed composition of urea resin, calcium alginate, polyoxyethylene alkylether, carbonitride, sodium benzoate, and oligomer. USE - Manufacture of buoy (claimed). ADVANTAGE - The method is environmentally-friendly, and enables easy manufacture of buoy having excellent workability, and prevents air leakage over time and maintains air pressure permanently to withstand water pressure in deep water.