Abstract: A special wax for sealing the plastic ball shell of the traditional Chinese medicine pill was prepared with excellent performances in deformation-resistance at high temperature and in anti-cracking at low temperature. Taking the mixture of fully refined wax No.54 and slack microcrystalline wax No.80 as base wax, the effects of diferent additives were investigated on the perfomances of the base wax melting point, viscosity and other properties. An optimum formula for preparing the sealing wax was determined that the dosage of low molecular weight polyethylene, C₅ petroleum resin, ethylene-vinyl acetate copolymer, auxiliary viscosity modifier A, coal based Fischer-Tropsch synthetic soft wax and amorphous poly alpha olefin was 1%, 1%, 0.5%, 3.0%, 20% and 1.5%, respectively. The special wax prepared under the conditions of 120 ℃, 30 min and stirring speed of 200 r/min has the advantages of nondeformation and non-cracking at 40 ℃ and －10—－20 ℃, is better than the reference sample.

Key words: traditional Chinese medicine pill, platic ball shell, sealing wax, kinematic viscosity