Plastic and nonmetallic article shaping or treating: processes – Pore forming in situ – By gas forming or expanding
Patent
1979-08-15
1981-06-23
Anderson, Philip
Plastic and nonmetallic article shaping or treating: processes
Pore forming in situ
By gas forming or expanding
165 86, 264 406, 264 455, 264216, 264DIG84, 425 89, 425144, 425224, 425817C, 432121, B29D 2704
Patent
active
042750245
ABSTRACT:
The densified area commonly formed during the manufacture of blocks of pliable polyurethane foam on a web of continuous material in a foaming tunnel is eliminated by controlled heating of the conveyor belt in the tunnel to a range between the densification temperature and the cracking temperature of the foam during the reaction period. An improved apparatus for this purpose comprises an enclosed, insulated housing and means for heating the conveyor belt such as hot air, infrared radiation, steam coils or electrical resistors. A preferred embodiment comprises heating the bottom of the foam block after it emerges from the foaming tunnel to a temperature considerably higher than that in the foaming tunnel. This eliminates completely any need for trimming off irregularities after removal of the web of continuous material.
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Knox, R. E. and R. H. Federroll, "Trouble-Shooting Guide for Molding One-Shot Resilient Polyether Foam", Wilmington, Del., E. I. Du Pont de Nemours, Inc.; Du Pont Aylene Foam Bulletin, Nov. 30, 1960, pp. 1-12.
Anderson Philip
TEC Foam S.A.
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