low viscosity epoxy resin degassing
low viscosity epoxy resin degassing
(OP)
Hallo everybody,
I have a problem, which has been discussed here before from some colleagues, but i can not find the thread. I am trying to deposit thin epoxy resin layers by the means of a spin coater (thickness of the layer 2-8 microns. The degassing of a low viscosity epoxy resin (500 mPas) under vacuum (1x10-3 bar) creates some problems, because even after 20 minutes there are still some air bubbles appear in the resin's volume (the resin's pot life is 30 minutes, so i can not afford to degas more than 20, because after that the resin will change its viscosity and this will cause an additional drawbacks during spin coating.)
Here I've read that one possibility is to reduce the resin's surface tension either by increasing the temperature or by additives such as BYK 051-054.
My question is what would happen with the resin's precuring time if i add BYK 051-054? Does this change the curing process and will this influence the overall stability of the full cured thin epoxy resin layer (will the resin be rigid or it will be viscoelastic after full cure)? And lastly what would happen if i add a different additive (acetone or heptane)? Thank you very much in advance.
K.E.
I have a problem, which has been discussed here before from some colleagues, but i can not find the thread. I am trying to deposit thin epoxy resin layers by the means of a spin coater (thickness of the layer 2-8 microns. The degassing of a low viscosity epoxy resin (500 mPas) under vacuum (1x10-3 bar) creates some problems, because even after 20 minutes there are still some air bubbles appear in the resin's volume (the resin's pot life is 30 minutes, so i can not afford to degas more than 20, because after that the resin will change its viscosity and this will cause an additional drawbacks during spin coating.)
Here I've read that one possibility is to reduce the resin's surface tension either by increasing the temperature or by additives such as BYK 051-054.
My question is what would happen with the resin's precuring time if i add BYK 051-054? Does this change the curing process and will this influence the overall stability of the full cured thin epoxy resin layer (will the resin be rigid or it will be viscoelastic after full cure)? And lastly what would happen if i add a different additive (acetone or heptane)? Thank you very much in advance.
K.E.





RE: low viscosity epoxy resin degassing
You need to apply vacuum for a few minutes to remove all air (which will be expanded by the volatile moisture and organics and flushed away). Then release the vacuum, and all the remaining bubbles will collapse and completely disappear. Acetone and heptane are simply volatile organics that help to remove air bubbles as I just described. At your level of vacuum you probably don't need to add any. But if you were to add acetone you still have to release vacuum to collapse the last acetone bubbles.
RE: low viscosity epoxy resin degassing
Nowadays i am repeating the experiment with exactly the same steps, but using different equipment (older one) and epoxy resin with lower viscosity (i was expecting to have even better results). The result is totally different - the resin does not boil at all....by applying the vacuum you can see only slight air separation, then this big air balloon observed previously with OV-11. First we thought that there is some leaks, but after checking we found out that the set up is correct. I've started to read in internet about this problem and subsequently found this site, where was written about the possibility that the surface tension of the resin can play major role in the degassing process.
Can you please provide some comments about this curious mismatch between the current results and these from UK, although we are using the same technological steps. Thans once again.
Kind regards:
/K.E./
RE: low viscosity epoxy resin degassing
RE: low viscosity epoxy resin degassing
Kind regards:
/K.E./
RE: low viscosity epoxy resin degassing
RE: low viscosity epoxy resin degassing