Cost estimation of butadiene-grafted polyvinyl chloride produced by gas phase radiation-induced graft polymerization

Butadiene gas in contact with polyvinyl chloride (PVC) powder is easily graft-polymerized onto PVC by Co-60 gamma irradiation. The product polymer has a high impact strength comparable with that of blended PVC and a modifier (ABS, MBS, chlorinated polyethylene, etc.) If the cost can be reduced to that of commercial high impact PVCs, the process will be feasible in industry. The pilot plant for continuous production of the graft polymer was constructed, and has been operated for some years. Its production cost has been estimated for the pilot plant and the conceptual commercial plant scaled up tenfold, on the base of construction cost of the pilot plant in 1968. Construction cost of the latter plant is estimated by Lang-Chilton's method. Operational costs and indirect costs are calculated by Winter's method on the basis of the construction costs. Final cost of the polymer is the sum of these costs and the material cost. Cost of the blended PVC and modifier is also estimated for comparison. The costs by the pilot plant and by the commercial plant are 185 yen/kg and 115 yen/kg of the polymer, respectively. The cost of PVC modified with ABS resin is 107 yen/kg on average. Further reduction of the cost is thus necessary to be competitive with the conventional high impact PVC. It was found that low impact resistance of the polymer with lower graft ratio can largely increased by addition of polyethylene. In that case, capacity of the plant can be raised. Consequently, the estimated cost of the graft PVC mixed with polyethylene is 105 yen/kg. (auth.)