Characteristics of polyurethane and elastomer parts for shoe industry produced by liquid injection molding technology

This paper presents the characteristics of the materials used in footwear industry, with a particular emphasis on polyurethane materials for making soles. The role, purpose and design of soles are also discussed, as well as the requirements this part of the shoe should satisfy. The manufacturing of polyurethane soles by liquid injection molding technology (LIM technology) is described, namely its two procedures. In the first one, the sole is obtained by pouring polyurethane into an open tool, and the second one is direct injection of polyurethane on the shoe upper in a closed tool, thus completing the production of finished footwear. The results of testing the specimens cut out from three sole samples show that almost all quality requirements under technical specifications for this part of the shoe are met. The tested sole samples do not meet the formal requirements for tensile strength, although the values of this characteristic in a sample made of a polyurethane-rubber combination and a sample made of elastomeric material are very close to the set quality requirements.