PROCESS FOR PREPARING CLOSED-CELL WATER-BLOWN RIGID POLYURETHANE FOAMS HAVING IMPROVED MECHANICAL PROPERTIES

摘要

The present invention is directed to a process for preparingwater--blown rigid polyurethane foams having at least an 80% closed-cellcontentwhich involves reacting a) at least one polyol mixture which is composedof (i) at least one polymer polyol; (ii) at least one polyol having a hydroxylvalue within the range of from about 200 to about 800; and (iii) optionally,at least one polyol having a hydroxyl value within the range of from about25 to about 115; with b) at least one polymeric isocyanate and/or aprepolymer thereof; in the presence of c) optionally, at least one catalyst;d) water; and e) optionally, at least one additive or auxiliary agent. Thepresent invention is also directed to the closed-cell water blown rigidpolyurethane foams produced by the process of the present invention. Theinvention is further directed to a polyurethane-foam forming mixture whichis used to produce the water-blown rigid polyurethane foams of thepresent invention. Foams produced according to the present inventionhave reduced friability and acceptable adhesion to substrates as well asacceptable compressive strength.