Cellular elastomer compositions
The present invention provides a process to preparing a polyurethane or polyurethane/urea closed cell foam. This foam, when compared to neoprene foam, exhibits a low water absorption and an additional quality of chlorine content of not greater than 0.5% based on the total weight of the closed cell foam.
1. A process for preparing a polyurethane or polyrethane/urea elastomeric closed cell foam, comprising the steps of:
a) blending components including at least one polyisocyanate with at least one polyol, and at least one blowing agent;
b) curing the blended components to form a solid polymeric elastomer, wherein the at least one blowing agent is dispersed in the elastomer; and
c) heating the solid polymeric elastomer to activate the at least one blowing agent and form a solid polyurethane or polyrethane/urea elastomeric closed cell foam
wherein the step c) is carried out in an oven with at least two zones set at two different temperatures and wherein the solid polymeric elastomer is passed through each zone at a speed to provide a dwell time at the particular temperature.
2. The process of claim 1 , wherein a C 2-10 diol chain extender is blended with the polyisocyanate, polyol, and blowing agent.
3. The process of claim 2 , wherein the C 2-10 diol is butanediol.
4. The process of claim 1 , wherein at least one amine catalyst is blended before curing.
5. The process of claim 1 , wherein the at least one blowing agent is azodicarbonamide.
6. The process of claim 1 , wherein the step of heating the polymeric elastomer comprises heating to a first and second temperature.
7. The process of claim 6 , wherein the first temperature is a temperature below an activating temperature for the chemical blowing agent.
8. The process of claim 6 , wherein the second temperature is a temperature sufficient to activate any blowing agent present.
9. The process of claim 1 , wherein the closed cell foam has greater than 10 ppi (pores per inch).
10. The process of claim 1 , wherein the closed cell foam exhibits a water absorption of not greater than 15% according to ASTM D1056 and not greater than 0.5% by weight of chlorine based on the total weight of the polymer composition.
11. The process of claim 1 , wherein the closed cell foam exhibits a compression deflection at 25% of from 1 psi to 13 psi according to ASTM D1056.
12. The process of claim 1 , wherein the closed cell foam exhibits a density of from 3 lb/ft 3 to 30 lb/ft 3 according to ASTM D1056.
13. The process of claim 1 , wherein the closed cell foam exhibits a tensile strength of at least 60 psi according to ASTM D412.
14. The process of claim 1 , wherein the closed cell foam exhibits an elongation of greater than 150% according to ASTM D412.
15. The process of claim 1 , wherein the closed cell foam exhibits a maximum compression and elevated temperature maximum compression set of less than 20% according to ASTM D1056.
16. The process of claim 1 , wherein the closed cell foam exhibits a fluid resistance of not greater than 75% according to ASTM D1056.