Non-foaming polyurethane help


Recently I posted a message asking for help making soft polyurethane foams and received some great help from the group. I ended up using a TDI and ethylene oxide prepolymer and an ethylene oxide/propylene oxide polyol. Now I have a related question - I'd like to make a solid version of my foam - I'd like to be able to pour this into a mold without having to use high temps or injection molding etc. When I say solid I mean the unfoamed polyurethane elasomer. I've tried a few things, simply leaving out the water or Dabco or both. What I get is fine but it takes about 48hrs to cure to a solid, which is way too long for my application. I'm using DBDTL as a catalyst and tried adding a little more to speed up the cure with limited success. Am I going about this the wrong way ? do I need a different catalyst ? should I be doing this in a solvent ? any help would be appreciated.

Kind regards,


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In a 100% solids set up such as this, it takes longer to cure as the time needed for the reacting and unreacted ends to find each other through diffusion increases greatly. Heat would help as it increases the mobility of things. Adding more catalyst will help but only to a point. Solvent would greatly increase the mobility of everything.

John Aspen Research, -

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John is right : trying to add some more catalyst has some limits. You can try different ones such as triethylamine or try different solvents which also have some effect on reactivity... But to some extent. As your chains get longer, it becomes harder for them to crosslink and when the prepolymer is too long, the curing process becomes really slow. In fact, you'll have to get the right compromise of chain length so as to get both softness and reactivity. You can choose to vary polyol chain length or isocyanate's, or both. Try !

Good luck. Let us know what you tried and get. Regards.

Nicolas DELFAU

a écrit dans le message de news:

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Nicolas DELFAU

It depends what you want to do with the non-foamed polymer... If you simply remove water from the formulation and use a Sn (or still better a Bi) fatty acid salt, you will not get the same polymer as in the foam. If the solid must have a (chemical) structure as close as possible to the foam itself, why not put the foam under some vacuum near the end of rise to make it collapse, or compress it mechanically to obtain a solid polymer?

"Nicolas DELFAU" a écrit dans le message de news:dsq5r7$qco$

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To make a solid elastomer you could try using a mercury based catalyst, such as Thorcat 535 - I know it's not pleasant but it works. Also, try looking at polyamines rather than purely polyols. This will give a certain amount of polyurea rather than just polyurethane, and can increase hardness a little but tends to be fairly effective in my experience. Normally when making a solid elastomer it is best to set out the characterstics you want as an elastomer and aim for them in formulation, rather than taking a foam system and removing the foamy bits. It is possible to make solid elastomers that cure quickly. We make two part elastomer adhesives that give structural bonds within 5 minutes, so many things are possible. Ours are all MDI based rather than TDI and they are designed to be pretty hard.

I take it from your email address that you are based in the UK. Give me a call if you want any further details.

Kind regards


Dr Colin Reed

Business Development Manager - Adhesives

Rosehill Polymers Ltd

Tel 01636 605233

Mobile 07795 413435

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Colin Reed

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