Process for preparing flexible polyurethane foams

A process for preparing flexible polyurethane foam having a modulus of at least about 2.3 which comprises subjecting to foaming conditions, a composition comprising:

• A 1. from about 50 to 100 parts by weight of a primary, hydroxyl-containing polyether triol having an average hydroxyl equivalent weight of from about 900 to about 2500,
• 2. from 0 to about 50 parts by weight of a polyol selected from a diol, a triol, a polymer-containing diol, a polymer-containing triol or mixtures thereof wherein said diols and triols have an average hydroxyl equivalent weight of from about 500 to about 2500 and said polymer has an average molecular weight of at least about 5000;
• B. an organic polyisocyanate consisting of
• 1. from about 50% to 100% by weight of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, NCO-containing prepolymers thereof, and
• 2. from 0 to about 50% by weight of an organic polyisocyanate having an average NCO functionality of at least 2;
• C. from about 1.0 to about 5 parts by weight of water per 100 parts by weight of Component (A);
• D. from about 0 to about 20 parts of a low boiling auxiliary blowing agent per 100 parts by weight of Component (A);
• E. from about 0.1 to about 10 parts per 100 parts by weight of Component (A) of a crosslinker composition consisting essentially of
• 1. from 5 to 100 percent by weight of compounds or mixtures of compounds represented by the formula ##STR15## wherein A is represented by the group ##STR16## each R, R.sub.1 and R.sub.2 are independently hydrogen or an alkyl group having from 1 to about 4 carbon atoms, x has a value from zero to about 4;
• y has a value of 1 or 2;
• z has a value of zero or 1, and when y is 2, z is zero and the sum of y and z is 2, as a primary crosslinker component, and
• 2.