POLYURETHANE PREPOLYMERS HAVING IMPROVED THERMAL STABILITY
Publication Date: 2003-Aug-20
The IP.com Prior Art Database
A prepolymer composition of a curing hot melt resin made from a polyester polyol copolymer (butanediol adipate:ethylene glycol adipate / 85:15 (w/w)), 0.2% by weight 2,2'-dimorpholinodiethylether (an endcapping and cure promoting catalyst), and 4,4'-methylene diisocyanate (NCO:OH / 2.0:1.0) was evaluated for green strength time after 2 and 16 hours aging at 250°F. Compositions containing no and 0.1% by weight UNILIN 550 wax were tested. Without the wax the green strength time was found to change from 7 minutes after 2 hours of aging to 8.5 minutes after 16 hours of aging. When wax was added the results were 4 minutes at both aging times. Similar results were obtained when the butanediol adipate:ethylene glycol adipate ratio was 90:10 (w/w). In this case, green strength times without the wax were 9.5 and 10.5 minutes at 2 and 16 hours heat aging respectively. With the wax they were 7.5 minutes at both aging times. This indicates the use of a crystalline, reactive wax provides both shortened green strength times and improved thermal stability.