Flexible polyurethane foam, process for its production, and seat for automobile using the flexible polyurethane foam

A process for producing a flexible polyurethane foam, which comprises reacting and molding in a closed mold a high molecular weight polyoxyalkylene polyol or a polymer-dispersed polyol comprising fine polymer particles in the high molecular weight polyoxyalkylene polyol, with a polyisocyanate compound, in the presence of a catalyst, a blowing agent consisting of water, a foam stabilizer, and an amino-modified silicone (F), wherein the amino-modified silicone (F) is present in an amount of from 0.00001 to 0.005 part by mass per 100 parts by mass of all active hydrogen compounds

• wherein the amino-modified silicone (F) is a compound represented by the following formula (1) or (2):
• provided that in the formula (1), R1 is a C1-10 alkylene group, R2 is a C1-10 alkyl group, and k is an integer of from 1 to 2,000, and
• in the formula (2), m is an integer of from 0 to 100;
• n is an integer of from 1 to 2,000;
• each of R3, R4 and R5 which may be the same or different, is a group selected from the group consisting of a C1-10 alkyl group, a C1-10 alkoxy group and a C1-10 alkyl group having a nitrogen atom, provided that when m is 0, at least one of R3 and R5 is an alkyl group having a nitrogen atom, and when m is from 1 to 100, at least one of R3, R5 and a “m” number of R4's is an alkyl group having a nitrogen atom,
• wherein said high molecular weight polyoxyalkylene polyol has an unsaturation value of at most 0.07 meq/g,
• wherein the high molecular weight polyoxyalkylene polyol has an average number of hydroxyl groups of from 2 to 6,
• wherein the high molecular weight polyoxyalkylene polyol has a molecular weight per hydroxyl group of from 1,000 to 5,000, and
• wherein with respect to a foam obtained by foaming into a thickness of 100 mm, the 25% hardness (ILD) X (N/314 cm2) measured in accordance with JIS K6400 (1997) and Y (mm), which is the value (difference in deflection on pressure side) obtained by subtracting the deflection on 500 N pressure side from the deflection on 900 N pressure side obtained from a load-deflection curve as measured by means of a pressure plate (Tekken Plate) in accordance with JIS E7104 (2002), satisfy a relation formula represented by the following formula (3):
• Y≧−0.000370842X2+0.225401X−10.5013 (3).

A flexible polyurethane foam obtained by reacting and molding a high molecular weight polyoxyalkylene polyol or a polymer-dispersed polyol comprising fine polymer particles in the high molecular weight polyoxyalkylene polyol, with a polyisocyanate compound, in the presence of a catalyst, a blowing agent consisting of water, a foam stabilizer, and an amino-modified silicone (F), wherein the amino-modified silicone (F) is present in an amount of from 0.00001 to 0.005 part by mass per 100 parts by mass of all active hydrogen compounds

• wherein the amino-modified silicone (F) is a compound represented by the following formula (1) or (2):
• provided that in the formula (1), R1 is a C1-10 alkylene group, R2 is a C1-10 alkyl group, and k is an integer of from 1 to 2,000, and
• in the formula (2), m is an integer of from 0 to 100;
• n is an integer of from 1 to 2,000;
• each of R3, R4 and R5 which may be the same or different, is a group selected from the group consisting of a C1-10 alkyl group, a C1-10 alkoxy group and a C1-10 alkyl group having a nitrogen atom, provided that when m is 0, at least one of R3 and R5 is an alkyl group having a nitrogen atom, and when m is from 1 to 100, at least one of R3, R5 and a “m” number of R4's is an alkyl group having a nitrogen atom,
• wherein said high molecular weight polyoxyalkylene polyol has an unsaturation value of at most 0.07 meq/g, and
• wherein with respect to a foam obtained by foaming into a thickness of 100 mm, when the deflection on 500 N pressure side obtained from a load-deflection curve as measured by means of a pressure plate (Tekken Plate) in accordance with JIS E7104 (2002), is from 5.0 to 55.0 mm, Y (mm), which is the value (the difference in deflection on pressure side) obtained by subtracting the deflection on 500 N pressure side from the deflection on 900 N pressure side, is from 22.5 to 33.0 mm.