Polyurethane foam questions

Hello all. I have a few questions regarding the starting materials for PUR foam manufacture.

In a generic formulation of TDI and polyol:

Will the temperature of the chemicals prior to mixing have an impact on the reaction? How? What will be the impact?

I understand that the freezing point of TDI is fairly low. How would it be affected if it froze in transit? Chemically, would there be any difference? Would there be any disassociation of components?

Is there a in-situ method for monitoring the reaction of these 2 components?

I'm considering the use of CO2 as a blowing agent. The CO2 will be mixed with the polyol, then fed into a mix head with the TDI. Are there any special precautions needed for this?

This chemistry is new to me and these will probably be the first of many qeustions. Thanks very much for any insight anyone can provide.



Reply to
Lance Genicola
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Since this post has sat a few days without any replies, I'll pick it up, although I don't feel the best qualified to answer, it is will show in the qualify of my answers.

Cooler temperatures will slow down the reaction. Temperature is a measure of the kinetic energy of the molecules, the higher the temp, the higher the energy and therefore the more reactive they are.

I don't think that TDI would be affected by freezing if it is thawed before the reaction. It is possible that it may pick up condensation which would not be too desirable.

There are certainly in-situ techniques available, but to mention a specific one is difficult without knowing the reactor you have. Can you take periodic samples? Can you look at thin sections? etc.


Reply to
John Spevacek

The temperature will influence the reaction kinetics of the TDI with the polyol. This can be studied by measuring the reaction exotherm immediately after mixing, by DSC (Differential Scanning Calorimetry). The measured curves can be interpreted by advanced kinetic modelling software. The resulting data can help you with defining the foaming conditions and components selection.

The main influence of temperature will be on the foaming process. Instead of mixing CO2 with the polyol it might be easier to add water to the polyol. The water will react with the TDI isocyanate resulting in the in-situ production of CO2. When additional blowing agents (pentane, HFC's) are added, these components will absorb the produced heat of polymerisation. Then the amount and heat of vaporisation of these blowing agents can control the foam temperature during foaming.

Chris Kooij Corus RD&T The Netherlands

"John Spevacek" schreef in bericht news: snipped-for-privacy@posting.google.com...

Reply to
Chris Kooij

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