Analysis of Polyurethane Foaming Flow

Abstract

Modeling of the polyurethane foaming flow process is difficult because the temperature, density, and thermal conductivity profiles change greatly due to the heat generation in the two-liquid mixture of polyol and polyisocyanate. The precise simulation of the polyurethane foaming flow process would be very effective for reducing the development period and production costs. In this study, the interdependence of heat generation reaction, density and thermal conductivity for polyurethane resin was determined experimentally. A foaming flow simulation was then developed by applying these relationships in a 3D flow simulation program. The following results were obtained by comparing the simulations with the experimental observations.(1) The temperature of the polyurethane resin in the foaming flow process rises greatly from the initial temperature to about 100°C due to the heat generation reaction. The resin temperature can be calculated with a precision of ±10°C even as the wall thickness and mold temperatures change.(2) The foaming flow analysis can reproduce (simulate) an increase in specific volume by 30-fold. The specific volume can be calculated with a precision of ±8% even as the wall thickness and mold temperatures change. At the end of the foaming flow process, however, the precision of the prediction becomes worse as the wall thickness changes.