Viscoelastic foam layer and composition
A viscoelastic foam system is provided having an amine-based polyoxypropylene extended polyol to impart strength, recoverability and endurance to the foam, and an appropriately selected non-amine-based polyol to provide flexibility to the foam. The combination of amine-based propylene oxide extended polyol and non-amine-based polyol provides a viscoelastic semi-rigid foam with excellent impact and recovery properties, recovering to substantially 100% of its initial volume and shape following an impact, yet with sufficient rigidity and stiffness so that it is effective at absorbing multiple impacts. A method of making the above viscoelastic foam is also provided.
1. A viscoelastic foam made from a Part A composition and a Part B composition, the Part A composition comprising 20-30 weight percent isocyanate (NCO) and the Part B composition consisting of:
(i) 50-80 parts by weight of propylene oxide-extended amine-based polyether polyol having substantially no ethylene oxide (EO) extension units;
(ii) 20-50 parts by weight of a non-amine filled polyether polyol;
(iii) 0.01-4 parts by weight of catalyst;
(iv) 0-1 parts by weight of a cross-linking agent;
(v) 1-6 parts by weight black paste;
(vi) 0.35-0.6 parts by weight surfactant;
(vii) 1-3 parts by weight water;
wherein all values expressed as weight percents are based on the total weight of the Part A composition, and all parts by weight are parts by weight of the Part B composition, said Part B composition having 100 parts by weight total polyols.
2. A viscoelastic foam according to claim 1 , said propylene oxide-extended amine-based polyether polyol being triethanolamine-based, said cross-linking agent being diethanolamine and said surfactant being silicone.