Hello guys,
At the moment I use a resin for my carbon products that has a 85 °C Tg . I post cure the parts up to 80 °c. But still it doesn’t like a day in the sun well, result print true even after a clear coat. Now I’m looking for a better infusion epoxy for my carbon products and there I have some doubts. What Tg do you guys use for carbon parts that will come in the sun on warm days up to 35°C or something ?
Thanx for the help.
I use Momentive Rim 935 with curing agent 937. I will get a resin from Axson the epolam 2031. Both have a TG of about 130C.
You could try an in-mould coating like Duratec Sunshield? I imagine more traditional clear coats like automotive 2k’s are too thin to hide any print through, but I certainly don’t have any issues with my parts sitting in the Aussie sun and my resin only has a Tg of 90.
I was looking at a recommendation of my supplier, this is the Renlam LY133. It has a Tg of 120 °C, the only downside it costs more then €20 a kilo. When I look at the resin for instance at Hp textiles they have one for €11 per kilo and a Tg of 98, but I have my doubts if that’s enough (it should be more then enough). My supplier also has other resins that have a tg that’s about the same as the HP textiles only they cost at least €5 per kilo more.
I work with an other in mould coating and I’m not planning to use an other coating. You should think a Tg of 85 whould enough in Holland but it has probably also to do something that’s it’s a cheap ass resin.
If you are worried about print the only thing that can help ist curing as slow as possible Without temperatur. The Rampf 2500 resin system is also great and has very low shrinkage.
I’m not worried for print true while I postcure it. Atfer curing I polish my parts ( clear in mould coating). But the problem is that even after curing and polishing or clear coat over in mould coating the part gets print true in the sun.
You will never see a part without that print! After month or years you will get that print.
I’ve heart different, but it shouldn’t be after a few days in the sun. Still not sure what do with the Tg, also the fact that its a cost thing. Maybe I give the HP resin a try and get some 120 Tg for my fuel tank, ect.
If you can postcure only at 80°C, than you need a resin that not only has a high TG, but also that has the property of being a “free standing posture” resin:
It increases its TG at a lower cure temperature than such TG temperature itself.
This is a property that very little resins have, but I consider it very important.
For example, the Axson 2015 (discontinued) in one of these. I’m now testing the 2019 for infusion.
If you want to go on the safe side (I say it because I tested it), go with the 2035 (for infusion) or the 2025 (for wet lay up). You have to heat the part into the mould at least at 50° before demoulding.
Never trust the data sheets: most brands are somewhat “optimistic” about their values… 
TEST TEST TEST!
I would also add that in all my work experience, I noticed that the real TG of a resin is directely proportional to its price.
The HP 120 resin will have the sane problem. Try to let it cure 1 week at RT and then start tempering.
I can’t cure at only 80 °C, I can cure at every temp. I want :p. But indeed I need a free standing postcure resin because of my in mould coating that doesn’t like curing in the mold. I experienced already that some brands are optimistic. Al I do is test test test hehe.
Hehe the price was very low on this resin so that explanes the low Tg.
Sometimes my parts cure for 2 weeks at room temp. and there is no difference.
I think I need to buy some resin and do some test $$$$$.