Rigid Isocyanate foams (MDI)

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Rigid foams for housing insulation require to meet certain flammability standard and also cost requirements. This foam utilizes a minimum of HCFC blowing agent and relies mainly on water for blowing.
Formulation Isocyanurate Spray foam Carbon dioxide and HCFC blown
Blowing Agent

Water

Water/HFC134a
Polyether polyol OH value 380 mg KOH/g Triol (CAS # 25791-96-2)

60

Sorbitol propoxylated OH value 380  (CAS # 52625-13-5) 30
Silicone surfactant 1.5
Tris(2-chloropropyl) phosphate (CAS # 6145-73-9) 10

Water

2.4-2.7

HCFC-134a blowing agent  (1,1,1,2-Tetrafluoroethane, CAS # 811-97-2 ) 0-3
Catalyst DMCHA (N,N-Dimethylaminocyclohexane, CAS # 98-94-2) 1.8
Catalyst PMDETA (1,1,4,7,7-Pentamethyldiethylenetriamine, CAS # 3030-47-5) 1.0
Catalyst organotin gelation (Dibutyltin bis(dodecyl mercaptide, CAS # 1185-81-5) 0.2
Polymeric crude MDI (CAS # 9016-87-9) NCO index 100 120
Density pcf 3.1 3.2
k-factor (BTU-in./hr-ft2-F) 0.18 0.195
Compressive strength (psi) 44 42
Dimensional stability, 28 days 100C -4 -1.3
Dimensional stability, 28 days 70C/97 % relative humidity        -3 -0.9
ICI Dimvac 14 days, 25C -8 -0.6
Open cell content, % 8
The use of water as the only blowing agent produces a foam with more of a tendency to shrink. Shrinkage can be reduced with the use of surfactants which produce more open cell structures. The addition of HCF 134 a requires a slight increase in catalyst to compensate for the lower processing temperature. Reduced shrinkage with the blowing agent is a result of slower diffusion of the blowing agent.


Last edited on:

November 16, 2006

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