Cellular polymer containing perforated cell windows and a process for the preparation thereof
AssigneeThe Dow Chemical Company
InventorsGuido E. Smits, Johan A. Thoen
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Abstract
A process for preparing a cellular polymer containing perforated cell windows in the presence of a perforating agent being a substance that has a critical surface free energy of less than about 23 mj/m.sup.2 is disclosed. The cellular polymers obtained according to this invention have a fine cell structure and show enhanced dimensional and thermal insulation stability. The invention also relates to rigid polyurethane foam prepared in the presence of, for example, particulate poly(tetrafluoroethylene) or a liquid polyfluoro- or perfluorocarbon, with a boiling point of at least 130.degree. C., as perforating agent.
Claims14
A process for preparing a cellular thermoset polyurethane polymer containing perforated cell windows by reacting an organic polyisocyanate with a substance containing one or more isocyanate-reactive hydrogen atoms/molecule in the presence of a perforating agent and a blowing agent wherein:
- the perforating agent, present in from about 0.01 to about 1.0 percent based on total weight of polymer, is a solid substance that has a critical surface free energy of less than about 23 mJ/m.sup.2 and an average particle size of about 20 microns or less;
- the blowing agent comprises water;
- and the isocyanate-reactive substance is a polyether polyol, polyester polyol, amine-terminated polyether, or mixtures thereof.
A polyurethane precursor composition comprising a polyurethane precursor, being a polyisocyanate or a substance containing isocyanate-reactive hydrogen atoms, and a perforating agent characterized in that the perforating agent is present in from about 0.01 to about 2.0 percent based on total weight of precursor and agent present and is a solid substance that has a critical surface free energy of less about 23 mJ/m.sup.2 and an average particle size of about 20 microns or less.
A cellular polyurethane polymer containing perforated cell windows and which has a density of from about 10 to about 150 kg/m.sup.3 prepared by reacting an organic polyisocyanate with a substance containing one or more isocyanate-reactive hydrogen atoms/molecule in the presence of a blowing agent and a perforating agent which has a critical surface free energy of less than 23 mJ/m.sup.2 characterized in that:
- a) the blowing agent comprises water in an amount to provide for at least 50 mole percent of the blowing requirements;
- and
- b) the perforating agent is particulate polytetrafluoroethylene, with an average particle size of about 20 microns or less, present in from about 0.05 to about 0.75 percent based on total weight of the polyurethane polymer.
Dependencies are inferred from the claim text.