The invention concerns a method for making a polyurethane foam by reacting
at least a polyester polyol with at least a polyisocyanate in the presence
of a foaming agent and a catalytic agent, such a polyester polyol having
been previously obtained by reacting a reactive acid A comprising at least
an aliphatic or aromatic polyacid with functionality not less than 2 with
at least a polyol P2 with functionality equal to 2 and at least an
aliphatic or aromatic polyacid with functionality not less than 2 with at
least a polyol P2 with functionality equal to 2 and at least a polyol P3
with functionality not less than 3, being thereafter called AP2P3, wherein
the catalytic agent at least partly consists of at least one amine
polyester polyol AP2P3, wherein at least part of polyol P3 consists of at
least a polyoxyalkylene polyalkanolamine having at least a tertiary amine
function, the alkanol radicals of said polyalkanolamine being C1-C6, the
alkylene oxide units being C2-C4 and the statistical mean of the number N
of alkylene oxide units per polyoxyalkylene polyalkanolamine being equal
to f.times.X, f being the number of hydroxyl functions per
polyalkanolamine molecule and X being a number ranging between 1 and 10,
inclusively.
