Patent ID: 6727292
Filing Date: 2004-04-27
Classification: C08G

Abstract:
A process for preparing flexible polyurethane foam comprising the steps of:A) providing a mixing apparatus capable of metering and mixing at least three separate reactive chemical component streams; B) providing a first reactive chemical component stream consisting essentially of a TDI series isocyanate composition; C) providing a second reactive chemical component stream consisting essentially of an MDI series isocyanate composition, wherein the MDI series isocyanate composition constitutes from 60 to 99% by weight of all isocyanates used in the process of preparing the flexible polyurethane foam; D) providing a third reactive chemical component stream comprising at least one polyol; E) providing a blowing agent consisting essentially of water, wherein the water in foam formulation ranges from 0.5 to 8.0 parts by weight, per 100 parts by weight of all polyols in the foam formulation (pphp); and F) metering and mixing together the first, second and third reactive chemical component streams and the blowing agent simultaneously by using the mixing apparatus under conditions suitable for the generation of flexible polyurethane foam; wherein the Isocyanate Asymmetry Factor (IAF) of the foam formulation, calculated according to Formula-I, conforms to the following: a) IAF ranges from 10 to 20, when the water content of the formulation is in the range of 0.5 to 2.0 pphp; b) IAF ranges from 20 to 30, when the water content of the formulation is in the range of 2.0 to 3.0 pphp; c) IAF ranges from 30 to 40, when the water content of the formulation is in the range of 3.0 to 4.0 pphp; and d) IAF ranges from 40 to 50, when the water content of the formulation is in the range of 4.0 to 8.0 pphp; whereinIAF=100[(pbw2,4â€²-MDI in formulation)/125.2+(pbw TDI in formulation/87]/[totalâˆ’NCO equivalents in formulation];â€ƒâ€ƒFormula I.