POLYURETHANE FOAM

PROBLEM TO BE SOLVED: To provide a polyurethane foam that is produced without causing scorch inside block even in slabstock molding and has excellent rigidity, hardness, dimensional stability, a shock absorption property and restoration property in spite of having a low density.SOLUTION: The polyurethane foam is obtained by reacting a polyol component comprising a polyol compound, a blowing agent, a foam stabilizer and a catalyst with an isocyanate component. (A) The polyol compound is a mixed polyol of four kinds of (i) an ethylene oxide-containing polyether polyol having a number-average molecular weight of 4,000-6,000 and a hydroxy value of 20-60 mgKOH/g, (ii) a polyether polyol having a number-average molecular weight of 300-1,000 and a hydroxy value of 100-800 mgKOH/g, (iii) a polyol for open-cell foam expanded with water, having an average hydroxy value of 200-600 mgKOH/g and a viscosity of ≤1,700 mPa s and (iv) a polyhydric alcohol and is adjusted to have an average hydroxy value of 200-300 mgKOH/g. (B) The foam stabilizer is a polyether-modified polysiloxane-based foam stabilizer. (C) The isocyanate component is crude MDI having an NCO content of 28-33% and has a closed cell ratio of ≤5%.