HAN YANG CHEMICAL CO., LTD. Began with the production of NASA SEAL?(Thread Seal Tape) in 1983, and it has been developing 100% POLY TETRA FLUORO ETHYLENE using special expansion methods since 1987, to supply ePTFE NASA SEAL? ePTFE POLYTOP SEAL?(Joint Sealant), ePTFE GASKET TAPE, PVC MAGIC TAPE and PVC FILM.