In Mold Coating under Prepreg?

General Composites Discussions Products Talk
#1

I was considering using the German advanced composites IMC but wonder if I would run into problems with the fact that some prepregs may need a higher temp cure than the 212F/100C? similarly with any automotive clears.

My thoughts are this:
In theory the imc may get a bit softer and the carbon weave may press into the imc layer but print through should be avoided since the curing process takes place in the mold and the mold surface would still be acting on the cosmetic side to give a flat finish.

Internal mold edges (anything greater than 180) may lead to the IMC thinning out (or split along the edge) as the stack and pressure squeeze down on these areas.

Any thoughts about these questions?

#2

Could you change to using some prepregs that cure at 100°C too?

#3

yes that should be a possibility except that there is a huge void in what Im capable to getting my hands on as far as prepregs are concerned.

#4

We sometimes use the IMC up to 140C° and it works.

#5

What does the manufactor claim ?
From a quick search i didnt notice that it can work with prepreg manufacture

#6

of course one issue with an IMC and prepreg is if/when you need to reposition your prepreg. Likely to lead to prerelease of the IMC.

#7

And if you have pinholes they are under the IMC so that will not prevent sanding and clearcoating.
IMC makes only sense if you have a perfect result even without it!

#8

thanks guys good food for thought!

#9

scott bader worked with advanced composites group a few years ago to develop a polyester gelcoat that was compatible with epoxy prepreg. im told tere was a very narrow window in which it would bond properly. I have had a crack with a nuplex styrene free gelcoat but the pinholes on the backside made it a no go.

#10

I tested the epoxy compatible Scott Bader gelcote on a test mould that is purpose made/shaped for some of my products with no luck, tried many times to the book?, gave up in the end lucky I did not try it on my dedicated moulds!.

#11

yeah, I think it has been discontinued now, really hit and miss, but perhaps a lot more miss.