Abstract: Disclosed is a polyol composition containing an aromatic polyester polyol having a hydroxyl number of 300-500 mgKOH/g and an average number of functional groups of 2.0-2.5, a medium-chain polyether polyol having a hydroxyl number of 100-250 mgKOH/g and an average number of functional groups of 2.0-4.0 and composed of a polyoxypropylene unit, and a long-chain polyether polyol having a hydroxyl number of 15-40 mgKOH/g, an average number of functional groups of 2.0-4.0 and an oxyethylene content of not more than 14% by weight and mainly composed of a polyoxypropylene unit.

Abstract: Disclosed is a polyol composition containing an aromatic polyester polyol having a hydroxyl number of 300-500 mgKOH/g and an average number of functional groups of 2.0-2.5, a medium-chain polyether polyol having a hydroxyl number of 100-250 mgKOH/g and an average number of functional groups of 2.0-4.0 and composed of a polyoxypropylene unit, and a long-chain polyether polyol having a hydroxyl number of 15-40 mgKOH/g, an average number of functional groups of 2.0-4.0 and an oxyethylene content of not more than 14% by weight and mainly composed of a polyoxypropylene unit.

Abstract: A soft polyurethane foam which has a rebound resilience percentage of not higher than 30% and whose temperature dependency of a compression force deflection that is represented by a difference between a 25%-compression force deflection value at -20.degree. C. and a 25%-compression force deflection value at +20.degree. C. is not larger than 0.030 kg/cm.sup.2.

Abstract: A flexible high-resilience polyurethane foam which has improved impact resilience and compression set, excellent effect on the reduction of transmissibility at 6 Hz and also improved mechanical strengths even under a reduced amount of a catalyst and is prepared by using, as an organic polyisocyanate composition, a mixture having a specified ratio of tolylene diisocyanate to polymethylenepolyphenyl isocyanate having a specific benzenoid composition or by using an isocyanate terminated prepolymer obtained by reacting the mixture with polyoxyalkylene polyol which has specific structure and is used for modification, and by using polyalkylene polyol which satisfies specific conditions in a hydroxyl value, monool content, and head-to-tail coupling selectivity; and a preparation process of the flexible high resilience polyurethane foam.

Abstract: A flexible polyurethane foam which has a low density, enhanced impact resilience, improved compression set and excellent effect on the reduction of 6 Hz vibration transmissibility and is obtained by a reaction of an organic polyisocyanate composition, that is, a mixture of (a) polymethylenepolyphenyl isocyanate containing from more than 60 to 90% by weight of a two benzene ring compound and having a weight ratio [three benzene ring compound]/[four or more benzene ring compounds + less active ingredient] of 1.1-20.0, and (b) tolylene diisocyanate in a ratio (a)/(b) of 97.apprxeq.80/3.apprxeq.20 by weight, or by reaction of a prepolymer derived from said organic polyisocyanate composition and a specific polyol, with a resin premix comprising a water blowing agent and an active hydrogen containing compound; and a process for preparing the flexible polyurethane foam.