Flexible foams comprising additives for improving hardness

A flexible polyurethane foam-forming composition comprising:

• (a) a polyol;
• (b) a polyisocyanate comprising toluene diisocyanate, the polyisocyanate having an isocyanate index of from about 70 to about 120;
• (c) a catalyst selected from an organotin catalyst;
• (d) a surfactant other than a polyether functional silicone (e);
• and
• (e) a polyether functional silicone of the formula:
• M*DxD″yM*
• where:
• M* is Ra(CH3)3-aSiO1/2
• D is (CH3)2SiO2/2
• D″ is (CH3)(R)SiO2/2
• x is 1-100;
• y is 1-20
• a is 0 or 1;
• R is polyether substituent CnH2nO(C2H4O)b(C3H6O)cR1 derived from a single type of polyether substituent, where R1 is —H, —R3N(H)R2, or —R3SH, R2 is H or a C1-C10 alkyl, R3 is C1-C10 alkylene;
• n is 3 to 4;
• b is a number such that the ethylene oxide residues constitute from about 30% to about 100% by weight of the alkylene oxide residues of the polyether substituent R;
• c is a number such that the propylene oxide residues constitute from about 0% to about 70% by weight of the alkylene oxide residues of the polyether substituent R;
• and the substituent R has a number average molecular weight of from about 200 Dalton to about 5000 Dalton, with the proviso that the flexible polyurethane foam-forming composition is free of a physical blowing agent except that the composition may optionally comprise carbon dioxide or methylene chloride, and wherein a foam produced from the composition is a flexible polyurethane foam.