Bonding FFKM & PCTFE at temperature in solvent atmosphere 1

[KENAT]

Bonding FFKM & PCTFE at temperature in solvent atmosphere

I’m involved in a project where we need to bond plastics like FFKM (Kalrez) & PCTFE (Kel-f) in a device that in service will see saturated solvent atmosphere ( DMSO, Acetone, Acetonitrile, toluene, dichloromethane among the most significant) to 100°C, or with less aggressive environment will see close to 250°C.

Previous research by a colleague (including some testing) for a slightly different application suggests that Torr-Seal has the best resistance to the solvents (out of adhesives he looked at) but possibly doesn’t bond the FFKM & PCTFE materials well and has a temperature limit of 120°C.

We typically use Chemgrip for bonding plastics like these but it does not stand up well to the solvents. We typically use MASTERBOND 10HT for high temp, but again not great with some chemicals.

I’m doing some digging and came across MasterBond EP45HT which claims solvent compatibility & good temperature performance does anyone have any experience using this

http://www.masterbond.com/tds/ep45ht?

(I’ll try contacting them but apparently my colleague had trouble getting information from them previously and had concerns about their claims for some other formulations so I thought I’d see if anyone here has used it.)

In my colleagues research he also came across D.E.N. 438 Epoxy Novolac Resin but didn’t get as far as testing it, and had concerns about it being tricky to work with in production.

A related formula D.E.N. 431 looks even better.

Another company they found was Arcor especially EE-101

Quick Google search turned up Loctite 325

If any one has any experience with these or suggestions of alternatives I’d appreciate it.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[btrueblood]

I do like Masterbond, they are responsive and helpful, and seem to keep innovating their product line (or at least advertising it well). They used to be pretty good about sending design engineers sample packs too, if you wheedled long Again, note the 20+ year old shelf life sticker on the data I provided earlier, sometimes new things happen in this world, and people come up with better ways to skin cats and things. As before, good luck.

 

[KENAT]

btrue, understood about the timeline on the info you gave, and I didn't mean to imply I thought you were full of it, just that my very quick browse didn't turn anything up.

I spoke to my contractor and he is going to contact Henkel, he already spoke to Lord and they couldn't help and he was having trouble getting in touch with Arcor. He's going to contact Green Tweed too I believe.

He also reminded me that we may not need the kel-f as we don't have quite the same list of chemicals (especially acids) that my torr-seal colleague had - so I've quit panicking.

My Director (who likes to dabble in things that grab his attention) looked over his records from when he was helping my Torr-seal colleague last year and may have something as well. Some HT adhesive from Midland that he has some good data on chemical compatibility and is good up to 240° (I hope he meant C not F).

Thanks for the input everyone.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[KENAT]

OK, sorry to resurrect this one, and maybe it should be a new thread but...

Am I right in thinking that Kalrez/FFKM is not a candidate for Ultrasonic Welding? The materials to join it to would be SST & Alumina.

This resource at page 10

http://www.henkelna.com/us/content_...e_Bonding_Rubber_Thermoplastic_Elastomers.pdf

suggests it's not a candidate but I haven't been able to find much else.

Cheers.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[btrueblood]

Kenat,

FFKM (and most all "elastomers") cures to its final form by crosslinking; applying heat (which is what the mechanical energy of ultrasonic bonding degrades to ultimately) will dissociate the crosslinks and/or burn/char the base polymer. So, it will never melt per se, and even if softened, won't re-bond even to itself, its material properties would have been destroyed.

 

[KENAT]

Cheers btrue, after I posted I did find a little more information and now your explanation helps tie it together.

I didn't think it was an option but wanted to be able to tell our production folks why.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[btrueblood]

Never hurts to post, Kenat, and I'd love to be proven wrong by the likes of Pat/Chris, there's new materials technologies coming along every day it seems.

To do a heat weld, you'd need to use a "thermoplastic elastomer" - see

http://en.wikipedia.org/wiki/Thermoplastic_elastomer

Most of them have pretty poor chemical/heat resistance.

 

[KENAT]

I was having trouble finding a source that definitively stated whether Kalrez was a Thermoset or Thermoplastic, my first response to production was along the lines that it wouldn't work for that reason but I wanted to be sure.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​