Polyurethane foam for steering wheel having improved water resistance

A polyurethane foam for use in a steering wheel of a vehicle, which is prepared by foaming a mixture comprising:

• (a) 100 weight parts of a polyol comprising:
• 60.0-95.0 wt % of a polyol having three functional groups and OH value of 20-40 mgKOH/g, which is formed by a chemical reaction between propylene oxide and ethylene oxide;
• 2.0-10.0 wt % of a polyol having two functional groups and OH value of 50-400 mgKOH/g, which is formed by a chemical reaction between propylene oxide and ethylene oxide;
• 1.0-10.0 wt % of a polyol having four functional groups and OH value of 500-800 mgKOH/g, which is formed by a chemical reaction between propylene oxide and ethylene oxide;
• and 2.0-20 wt % of a polyol having three functional groups, OH value of 10-30 mgKOH/g and solid value of 30-50%, which is formed by a chemical reaction between propylene oxide, ethylene oxide and styrene monomer;
• (b) 30-70 weight parts of an isocyanate comprising 0.1-30 wt % of monomeric methylene diphenyl diisocyanate (MMDI);
• 5-70 wt % of carbodiimide-containing methylene diphenyl diisocyanate;
• 0.1-90 wt % of polymeric methylene diphenyl diisocyanate (PMDI) having molecular weight of 6,000-15,000;
• and 0.1-90 wt % of a prepolymer having an increased molecular weight by using methylene diphenyl diisocyanate (MMDI) with molecular weight of 2,000-6,000;
• (c) 1-10 weight parts of glycol having OH value of 1500-2500 mgKOH/g;
• (d) 0.1-1.0 weight parts of butandiol having OH value of 500-1500 mgKOH/g;
• (e) 0-5 weight parts of glycerol having OH value of 1500-2500 mgKOH/g;
• and
• (f) 0.01-4 weight parts of water.