Solvent for Epoxy and Polyurethane

Hello anitoff

<"....http://www.crosslinktech.com/FAQ/Removing%20cured%20products.htm

How to remove cured Epoxy or Polyurethane

At best it is difficult to remove cured material without damaging the encapsulated components. In certain instances however, where the embedded component is reusable, such as an encapsulated conductor, it is worth while to remove the encapsulant an d reclaim the part.

The easiest method to remove epoxy or polyurethane is to heat it above its glass transition (softening point) temperature. At this point the encapsulant will be soft enough to cut or penetrate with a chisel like device and break it away from the embedded component. This method is more convenient for recovering heavier solid components than reclaiming delicate electronic circuits. Epoxies and polyurethanes will smoke and give off odours when heated to high temperatures. Provide an appropriate face mask and good ventilation while removing the encapsulant using this method.

The other method is to immerse the encapsulated component in Methylene Chloride. This solvent is hard to obtain as it has been declared a carcinogen. The user must take all precautions to prevent contact with skin and not to inhale the vapours while using this product. Methylene Chloride will cause the encapsulant to swell and become soft for removal. Unfortunately, since printed circuit boards and many electronic components are also encapsulated with epoxy, they will also be damaged or destroyed by this solvent.

There has been some success reported in using the commonly available paint stripper sold under the trade name Circa 1867. Immersing the encapsulated component in this material will also soften the encapsulant the same as Methylene Chloride and of course, it will also attack and destroy any embedded epoxy devices.....">

<"....http://www.eng-tips.com/viewthread.cfm?qid=127897&page=6

Polyurethane is not one chemical type but covers a wide range of polymer and therefore general statements are not so easy to make. Polyurethanes are polar and so you need a polar solvent like MEK, acetone etc. The problem is that usually the polyurethane is cross-linked (like a thermosetting polymer) and it is therefore not possible to dissolve them at all. The best you can do is swell them. So the answer to your question is that you probably cannot dissolve the polyurethane.

NMP has been sometimes recommended. Visit

http://p2library.nfesc.navy.mil/P2_Opportunity_Handbook/5_10.html

Otherwise, as Demon3 said, usual solvents may soften the polymer for further mechanical removal.....">

As you can see, it all depends on the particular formulation of the cured epoxy and polyurethane.

Some 40 years ago, we had occasion to dissolve cured epoxy from electronic circuitry embedded in cast epoxy resin.

Sadly the Government Department (NZ DSIR) was closed years ago, and anyway all staff would now be retired - but I do not know the formulation of that epoxy resin, nor the solvent used to dissolve the cast epoxy.

Kind Regards....