| 摘要 |
A method for making a rigid polyurethane foam by reacting a polyisocyanate and a polyol in the presence of a urethane catalyst, a blowing agent and a silicone surfactant characterized by employing a blowing agent comprising a C4 or C5 hydrocarbon, or mixtures thereof, with an average molecular weight of <=72 g/mole and a boiling point in the range of 27.8 to 50° C., and a silicone surfactant comprising a polyether-polysiloxane copolymer represented by the following formula: <?in-line-formulae description="In-line Formulae" end="lead"?>(CH<SUB>3</SUB>)<SUB>3</SUB>-Si-O-(Si(CH<SUB>3</SUB>)<SUB>2</SUB>-O)<SUB>x</SUB>-(Si(CH<SUB>3</SUB>)(R)O)<SUB>y</SUB>-Si(CH<SUB>3</SUB>)<SUB>3 </SUB><?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?>where<?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?>R=(CH<SUB>2</SUB>)<SUB>3</SUB>-O-(-CH<SUB>2</SUB>-CH<SUB>2</SUB>-O)<SUB>a</SUB>-(CH<SUB>2</SUB>-CH(CH<SUB>3</SUB>)-O)<SUB>b</SUB>-R'', and<?in-line-formulae description="In-line Formulae" end="tail"?> where R'' is H, (CH<SUB>2</SUB>)<SUB>z</SUB>CH<SUB>3</SUB>, or C(O)CH<SUB>3</SUB>; x+y+2 is 60-130; x/y is 5-14; z is 0-4; the total surfactant molecular weight, based on the formula, is 7000-30,000 g/mole, the wt % siloxane in the surfactant is 32-70 wt %, the blend average molecular weight (BAMW) of the polyether portion is 450-1000 g/mole, and the mole % of ethylene oxide in the polyether portion is 70-100 mole %.
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