Flexible polyurethane foam having prolonged recovery time

A method of making a flexible polyurethane foam, comprising reacting, at an isocyanate index of 60 to 110, a reaction mixture comprising

• A) a polyether polyol having a hydroxyl equivalent weight of no greater than 225 or mixture of two or more such polyether polyols, wherein the polyol or mixture of polyols (i) has a number average hydroxyl functionality of 2 to 4;
• (ii) includes at least one polyether polyol that has a hydroxyl number of less than 170 and (iii) has an oxyethylene content of at least 10% by weight and/or includes at least one polyether polyol that contains at least 40% by weight oxyethylene units;
• B) 1 to 5 parts by weight water per 100 parts by weight of component A), with
• C) at least one organic polyisocyanate,
• in the presence of
• D) at least one catalyst for the reaction of an isocyanate group with water and/or an alcohol;
• E) at least one foam stabilizing surfactant,
• F) 1 to 45 parts by weight of a tackifier per 100 parts by weight of component A) wherein
• (i) the tackifier has a viscosity of at least 5,000 centipoise at 25° C., and
• (ii) the tackifier has a glass transition temperature of at most 20° C., and
• G) 0.05 to 10 parts by weight per 100 parts by weight of component A) of at least one monoalcohol, the monoalcohol being characterized in having at least 4 carbon atoms, a molecular weight of up to 300 g/mol and a viscosity of up to 500 cps at 25° C. as measured using a cone-and-plate viscometer, provided further that the weight proportion of components F) and G) is at least 20:80 but not greater than 95:5;
• wherein components F) and G) are pre-blended prior to being combined with either of components A) and C) to form a pre-blend having a viscosity of no greater than 20,000 cps at 25° C. as measured using a cone-and-plate viscometer.