Importance

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Abstract

In a process of generating a polyurethane foam by forming a mixture including isocyanate and polyol reactants, catalyst, and blowing agent, which mixture reacts exothermically to yield a rigid polyurethane foam, there is included in the mixture expandable polymer beads, made of a thermoplastic polymer (e.g., polystyrene or a polyolefin) that has a softening point at or below the maximum temperature reached during the exothermic reaction. The beads may be added in unexpanded form, partially expanded form, or fully expanded form. The heat of the urethane-forming reaction causes the beads to sinter, creating hollow polymeric spheres in the foam, which are larger than the cells in the polyurethane matrix, and which appear to improve the foam's crush resistance.

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First Claim