A mold foaming process for preparing thermoplastic polyurethane foam sheets was proposed and realized in pilot scale hot-press machine based on the mechanism of solid-state polymer foaming. Thermoplastic polyurethane microcellular sheets with volume expansion ratios of 2.2–7.0 were prepared by adjusting foaming temperature of 95–120°C at the fixed CO2 pressure of 12 MPa with natural post-curing. The good foam dimensional stability and the uniform cell morphology of these thermoplastic polyurethane foams suggested that the mold foaming of thermoplastic polyurethane sheet was feasible. Regardless of volume expansion ratio, a linear shrinkage of 17–19% occurred to all thermoplastic polyurethane foams after post-curing. The flexible properties of these post-cured thermoplastic polyurethane foams, such as hardness, rebound resilience, compression set, and dynamic shock absorption, were investigated. The test results indicated that these thermoplastic polyurethane foams were excellent flexible materials.
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