(DE19526979-A1)      The novel feature in rigid foam prodn. from polyisocyanates, high mol.wt. cpds. with 2 or more reactive H atoms and opt. also chain extenders and/or crosslinkers is that the blowing agent is a mixt. of (i) a low boiling 3-7C hydrocarbon; and (ii) a low mol., monofunctional, primary or secondary OH gp.-contg. 1-4C alcohol.    The (i)+(ii) mixt. is also claimed per se and can be used in combination with CO2 produced in situ from water and the isocyanate.    ADVANTAGE -   The problems associated with prior-art blowing agents are overcome, in particular the foaming effect and flow properties are improved so as to yield a rigid foam for use in insulation.    (JP9104781-A)      The novel feature in rigid foam prodn. from polyisocyanates, high mol.wt. cpds. with 2 or more reactive H atoms and opt. also chain extenders and/or crosslinkers is that the blowing agent is a mixt. of (i) a low boiling 3-7C hydrocarbon; and (ii) a low mol., monofunctional, primary or secondary OH gp.-contg. 1-4C alcohol.    The (i)+(ii) mixt. is also claimed per se and can be used in combination with CO2 produced in situ from water and the isocyanate.    ADVANTAGE -   The problems associated with prior-art blowing agents are overcome, in particular the foaming effect and flow properties are improved so as to yield a rigid foam for use in insulation.    (CN1145913-A)      The novel feature in rigid foam prodn. from polyisocyanates, high mol.wt. cpds. with 2 or more reactive H atoms and opt. also chain extenders and/or crosslinkers is that the blowing agent is a mixt. of (i) a low boiling 3-7C hydrocarbon; and (ii) a low mol., monofunctional, primary or secondary OH gp.-contg. 1-4C alcohol.    The (i)+(ii) mixt. is also claimed per se and can be used in combination with CO2 produced in situ from water and the isocyanate.    ADVANTAGE -   The problems associated with prior-art blowing agents are overcome, in particular the foaming effect and flow properties are improved so as to yield a rigid foam for use in insulation.