In 2005, the polyiso lamination industry experienced a shortage of polymeric isocyanate. This shortage also brought rising costs of isocyanate. To counteract the situation, the polyiso laminators looked to reducing isocyanate consumption. The polyester polyol producers were asked to develop polyester polyols in the 200 OH NO range as this would save about 7 to 10% of the isocyanate usage. Reducing the OH NO of a polyester polyol alone will cause the 2.5 index foam to be softer and depending on the polyester polyols could reduce the dimensional stability of the foams. Additionally, the lower OH NO can also cause deterioration in the thermal stability of the foam if the polyol is not designed properly. Oxid will show through laboratory work that the minimum OH NO should be 200; that as the OH NO is reduced, the functionality of the polyol should be increased to minimize a reduction in dimensional stability; and that the aromatic content should be increased to improve thermal stability.
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