Water-blown polyurethane sealing devices and compositions for producing same

A polyurethane composition suitable for the preparation of a molded polyurethane article, the composition comprising:

• (I) an isocyanate prepolymer composition having a % free NCO of less than 20 and a viscosity of from 100 to 700 cPs, the composition comprising the result of reacting:
• (a) an isocyanate blend comprising:
• (i) 0 to 10 pbw 2,4'-diphenylmethane diisocyanate;
• (ii) 30 to 80 pbw 4,4'-diphenylmethane diisocyanate;
• and
• (iii) 1 to 10 pbw of a mixture of uretonimine containing molecules and carbodiimide containing molecules;
• and
• (b) from 10 to 70 pbw of an ethoxylated and propoxylated glycerine having a number average molecular weight of between 1000 and 10,000 and a hydroxyl number of between 20 to 100, wherein all pbw are based on the total weight of (a) and (b);
• (II) an isocyanate-reactive component;
• (III) a chain extender;
• and
• (IV) a blowing agent comprised of water.