| 摘要 |
<p>A compsn. to be foamed comprises an expandable polymer compsn. contg. (a) an oligomer of formula: H-(NH-NH-CO-O-A-O-CO)-nX (where n is 1-100; X is Cl, Br or I; A is 2-6C alkylene, 6-12C arylene, 4-12C oxydialkylene, 12-20C oxydiarylene, (1-6C alkylene)diphenylene, or (1-6C alkylidene)diphenylene) or (b) a cyclised form of (I) or (c) a condensate of formula ROOC-NH-NH-CO-O-A-O-CO-NH-NH-COOR' (II) (where R and R' are same or different, are 1-8C alkyl, 5-8C cycloalkyl, 6-10C aryl or 7-10C aralkyl or alkaryl). The foaming agents are novel cpds. and decompose at >200 degrees C. Below this temp. they are stable and show little tendency to sublime. They are prepd. by reaction of polyfunctional (pref. difunctional) haloformates with hydrazine (to give (I)) or hydrocarbylcarbazates (to give (II)).</p> |
