| 摘要 |
Polyurethane foams are prepared by establishing a quantity of polyol in a container having an outlet dispensing into the polyol, adjacent the outlet of the container a predetermined quantity of a catalyst(s) for promoting the production of polyurethane, discharging through the container outlet a predetermined quantity of the polyol/catalyst(s) mixture into a mixing means and whilst holding the mixture in the mixing means, dispensing a predetermined quantity of diisocyanate into the mixing means without it having come into contact with the polyol before entering the mixing means, mixing the ingredients and finally discharging the mixed materials. The mixing may be commenced when all the ingredients have been dispensed or prior to the dispensing of the diisocyanate into the mixing means, and the mixing head may be pressurized during mixing. The container referred to above may in fact be communicating liquid lines which lines carry the polyol and catalyst(s) respectively. A fluorocarbon may be incorporated in the reaction mixture and suitably enters the mixing head admixed with the diisocyanate. The diisocyanate exemplified is toluene diisocyanate.ALSO:The mixing head of Specification 1,071,082 (see also (1), Figs 1 and 2, not shown) is supplied with polyurethane foam ingredients watered by reciprocating pumps operated by pneumatic actuators as at (4), (6), Fig. 1; catalysts from liner (14), (15) are first mixed with the polyol in line (7) and a fluorocarbon from line (18) with the diisocyanate in line (9). Pressure air from line 29 is used to operate the pump actuators; pressurize the mixing head during operation; actuator the mixer let-down valve (41); form a solvent/air purging mixture, and move the solvent receiving cup (43). A controller (44) operates solenoid/air valves sequentially, a mixing cycle comprising pumping ingredients in predetermined sequence; starting mixing motor; pressurizing mixing head; opening let-down valve and stopping motor; positioning cup (43) under mixer and purging with air/solvent blast while running mixing motor; and re-setting for next cycle. The ingregdients may be re-circulated during idling. |
