Curing release agent FREKOTE 770-NC in the oven (60-80ºC / 140-175ºF)

[drodrig]

Hi there,

I heard it is good to cure the release agent FREKOTE 770-NC in the oven at 60-80ºC / 140-175ºF for an hour.

Does anybody any experience doing this? Would you recommend it?

It is time consuming and adds dead time.

thanks
regards,

 

[btrueblood]

https://www.henkel-adhesives.com/us/en/product/mold-release-agents/loctite_frekote_770nc.html

The data sheet talks about applying other releases and sealers, and fully curing them, prior to applying 770-nc at room temp. to 60C. No mention of curing, just applying several coats and letting the solvent flash off for 5-10min. between coats, then re-applying as necessary to maintain release.

 

[drodrig]

Yes
It talks about the Frekote PMC for cleaning.

It doesn't say anything about the curing, but I understood it is good to cure it. That's why I am confused.

We have an aluminium mould (if this makes a difference)

thanks

 

[Compositepro]

770 is a moisture curing material. It reacts with atmospheric moisture to chemically cross-link (cure). Almost all chemical reactions are accelerated by heat. Degree of cure (completion of the reaction) depends on time and temperature and rarely reaches 100%. You will almost always achieve a higher degree at higher temperatures than can be achieved at lower temperatures, regardless of time. Any reactive groups left in the release coat can potentially react with the resin that you are molding, which results in adhesion.

Curing the release at 60-80C would certainly help but may not be absolutely necessary. However, almost all release problems occur on the first molding cycle after a mold has been coated for the first time. So the first-time treatment of a mold should be five applications of mold release and then one temperature cycle up to the cure temperature that will be used in production. Keep in mind that autoclaves are pressurized with compressed air or nitrogen, which is very dry.

 

[drodrig]

Hi,

This is very valuable information.

We will pay lots of attention with the first coating (including the 80ºc curing) and then go on without the oven

thanks
regards,

 

[btrueblood]

I think CP is recommending you DO run an atmospheric, or moist, oven cycle at your normal operating/molding temperature.

 

[drodrig]

Yes, for the first use.

We will cure the Frekote coatings in the oven. Then the normal lamination / prepreg curing

 

[Compositepro]

That is correct. As I said, when release problems are encountered it is almost always on the first time run of a tool (mold). The common advice that I have heard is to use five initial coats. These coats are very thin and no visible liquid should be left on the surface after the each application by using a dry buffing cloth and then allowing a cure period. It is not a common practice, however, to bake tools at part curing temperatures prior to the first molding cycle. This perfectly explains why first time cures on tools are so problematic.