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Rigid polyurethane foam production methods

Update Time:2011-05-27   Writer:Arima
Rigid polyurethane foam manufacturing method is divided into: spraying and pouring method:
1, the casting method: one is the raw material mixed into the cavity after the pouring foam, foam after the foam and fiberglass shell form a whole. The products produced by this method are sandwich fan blades. However, the refrigerator must shell, insulation glass, steel water tanks; the other is to pour foam into the mold, the molding removed from the mold after the foam, this foam layer outer surface smooth, hard surface without Foam .
Casting method is divided into two kinds of hand-cast and machine casting. However, most of the use of machinery in the production of foam casting, mechanical foam mixture by metering pump at the raw material into a continuous foam machine mixing chamber, mixed, and rapidly injected into the cavity or mold, then curing.
Of rigid foam casting molding factors: ① measurement precision. The production process, measurement accuracy should be controlled within 2%, ② ambient temperature suitable forming temperature 20-30 ℃, the temperature can be slightly higher raw material, the ambient temperature is -5, you can still produce, but the cream time to Chairman , the capacity is too large; ③ mold temperature. Low temperature cause the product density, form thick-skinned: ④ time control operation, the material stays in the foam of the mixing chamber is about 10s, into the mold time for 30-60s cream filling and the expansion set (gel) time is 2 - 3min: ⑤ aging (curing). After gel foam, heat cured before demolding.
Ejection time is inversely proportional to the heating time, heating to 65 degrees, the need to 6h stripping, heated to 802-90 °, the ejection time was 4h, the heating of 100 degrees, the mold release time was 2h, stripping, the foam plastic to be cooled to room temperature.
2, injection molding: injection molding of rigid polyurethane production process, the spray gun. Production, the first two components of materials Stir into the tank, respectively, the ratio required by the traffic regulation 5min, the error should not exceed 2%, the material lost by 3 and the gear pump into the gun barrel 10 within 8 compressed air 9 to 10 in the two groups mixed in the gun, atomizing spray to undertake the surface, the spray gun to undertake surface distance 200-500mm, polyurethane foam injection molding process conditions were: cream time 3-7s, easy to plug the gun too fast, too slow and easy loss, swelling time, and environmental temperature should be flexibility; spraying speed
Often used 4-5ky/min, atomizing air pressure 0.5-0.6mpa (5-6 kg/Cm2), temperature control, following a surface temperature should be greater than 10 ℃, the material temperature is 20 degrees, the temperature of hot air into the spray gun
Is 40-80 ℃
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