Preparation and Properties of an Internal Mold Release for Rigid Urethane Foam.

Most mold release agents used in the molding of rigid polyurethane foam are applied to the internal surfaces of the mold. The commonly used mold release agents include waxes, fluorocarbon materials, soaps, and silicone oils. These materials form a thin layer between the surface of the mold and the foam, allowing for easy release of the molded parts. This type of mold release must be applied prior to each molding operation and, after repeated use, cleaning of the mold is required. Small amounts of this mold release are transferred to the molded part, resulting in a part with poor surface bondability characteristics. An internal release agent, which can be mixed in a urethane foam resin was investigated. Internal mold release agents were prepared in the laboratory and evaluated. The internal mold release provided good releasability and resulted in urethane foam that has excellent surface bondability. Thermomechanical and solvent extraction data indicate that no compatibility problems would be expected from the use of this type of release agent.