Hi,

I've laminate a sheet of the Diolen 200g black with 72h epoxy (1h work, bought from a local dealer)
the surface was a peel ply surface (the red line one you offer)


I have a specific project with a hard requirement that i need to glue the Diolen to birch baltic plywood.
I've created a test with multiple glues to try and set them up 
But never actually got to test the glues themselves because the surface of the laminated Diolen was the first one to fail, detaching from the wood leaving the peel ply surface on the wood and came out bare bone.

Now one reason can be the epoxy itself, which i think is less likely
The lamination process itself could be the problem? just a fabric on the table with some weight on it (flat object)

Can it be that Diolen does not bond to the epoxy very well?

* I've done a video of the process, posting it is a lot of work for me but if its crucial to figuring it out i will post it per request.

Will appreciate your help, i'm working on it for a long time and its currently a bust, i'm discouraged

Epoxy bonds to Diolen very well.

I'm a bit confused about what you are actually doing, can you post some photos? Video probably  not necessary, but some photos would help.

What are you gluing if the Diolen is already bonded to the wood? Why does the wood have a peel ply texture? Are you first laminating the Diolen with peel ply, letting that cure, then removing the peel ply and bonding to the wood? If so, how are you bonding it to the wood, just the same laminating epoxy? If that is the case, what are the glues for? Why not just laminate the Diolen to the wood directly?

My initial suspicion is the epoxy, can you tell us what it is or post a TDS for it? A 72 hour epoxy does not sound like a room temperature cure epoxy, it sounds like it would need some sort of elevated temperature cure to achieve it's full properties. If this is the case, then it will be extremely brittle after curing at room temperature, and extremely easy to peel apart as a result.

Hi thanks for your reply!

I'm first laminating the Diolen with peel ply and then glue it to the wood.
I don't laminat it directly to the wood because it has a more complex shape then just a flat surface, so i mould it and then glue it to the wood.
This test was with a sheet just to make it easy.


In this photo you can see on the bottom the laminated sheet with the peel ply surface side
On the top there are 2 cuts that i glued then peeled
And in the background the wood with the test

The peel test showed that at 3-5 KG peel force it will come off (which was really easy, almost no force was needed)
I'm using different glues just to just, one of them was the lamination epoxy (others are super glue and such)

As for the epoxy - the company is KUKDO
Here is the specs:
https://sfilev2.f-static.com/image/users/423667/ftp/my_files/Srafim/epoxy/YD114.pdf?id=27488963
https://sfilev2.f-static.com/image/users/423667/ftp/my_files/Srafim/epoxy/KH-816%20%D7%9E%D7%A7%D7%A9%D7%94.pdf?id=27808057

Yeh, so the thing that stands out to me is that data sheet says 7 day cure time at room temperature. How long did you leave it before trying to peel it, and what was the ambient temperature? 

The other thing is the two strip's that have delaminated, you can see it has actually left the resin behind on the wood and peeled it from the Diolen. This indicates a brittle resin, which would again suggest the resin is under-cured. I feel this will be your issue. If you are sure you are weighing and mixing accurately, then try leaving it for longer or warming it up a little bit.

Otherwise, several other issues could include:

The moisture content of the wood can effect the bond strength. I dont feel this will be the issue as you can see the resin has bonded well to the wood, it hasn't peeled from the wood.

Poor bond gap. Secondary bonds need an appropriate amount of adhesive between the laminate and the substrate you are bonding to. Laminating resin is generally unsuitable for secondary bonding as it is too thin to properly fill the gap between the substrate and the laminate. Wood can make this worse, because it absorbs the resin and takes it away from the joint, leaving an even leaner joint. Superglues are also generally too thin for this - you really want a paste or at least a gel for a proper secondary bond. Also not sure what other glues you are trying, but just keep in mind epoxy can be reasonably difficult to bond to because of their thorough cure, you should ideally be using a product made for bonding epoxies and not a general purpose adhesive (obviously not the issue here, but just thought it worth mentioning).

Again, I don't feel bond gap is your problem here - there appears to have been a sufficient amount of resin to have achieved a decent bond, so the viscosity of the resin shouldn't have been an issue in this case. It is possible the wood absorbed too much resin and made it a bit lean, but it doesn't appear that way. I would still put money on it being an under curing issue.

Thanks! 
The hardener says 7 days but the resin says 24h, i'm not sure what this means

The product description made me a bit worried thu -


No wording on fabric lamination, do you know this product? is it suitable?

Either way, here is the timeline process:
From lamination to cut - 3 days
from gluing to peeling - 4 days
Room temp is around 25 day and 20 night
So it should have been fine i guess
I've tested gel super glues

Your advice about gluing epoxy is extremely important for me and very helpful!
Can you recommend a glue that will be suitable for the job?

The thing that i'm suspecting is the mixing ratio - it says 3/1 but the orders i got from the store are for 100g resin/ 60g hardener

Well I would say the hardener is a 'slow' hardener, and the TDS for the resin is when used with a different hardener. 

And yes, it does not sound like the most suitable product. However this is more of an issue for laminate strength than adhesion, so I would say that's more likely a bit of a different issue that you haven't come to yet. But yes, it could potentially be part of the problem. In general, I think this epoxy is the problem. I feel if you switched to a purpose made laminating resin, you would find this issue disappears. That isn't to say you can't get this one to work - but I do think your best option would be to switch it.

Ya, I just paid so much for it, 5KG
Trowing it away and buying a new is a lot of money
I've sent an email to the epoxy company themselves to understand where is the fail


Can you shed some light on the type of glues that can bond to epoxy?
I don't find any that specifically claim that

Thanks!

Yeh understandable, but if it doesn't work for what you're doing then you're throwing away your time, which is worth a lot more. Anyway, if you want to keep trying it, I would suggest keeping it warmer for a good amount of time. Put it in a box in front of a heater, see if you can get it as high as 50-60° C. Even 30-40° would help. Keep it there for a day or two (obviously not unattended) and see if that helps. 

Sealing the wood is also not a bad idea, just brush a coat of resin on and let that cure solid, then scuff it up with 120 grit before trying to bond your laminate on. This will stop the wood taking resin out of the joint.

As for glues, its difficult to suggest anything without knowing what part of the world you're in, but you're probably not finding anything because you're using the wrong search term. Technically a 'glue' is an adhesive made from an organic compound like animal collagen, and these are not what you are wanting. Search for synthetic adhesives. There are an plethora of options, from epoxies to polyurethanes to acrylics, etc. You don't need anything fancy, so possibly look for a construction adhesive like Megapoxy 69, that would be my pick for this application.

Every word is golden

Cheers mate, thanks a lot!

A quick update:



I did another test:
Changed Epoxy ratio from 100/60 to 100/50
4 variations:
2 400gm
2 200gm
one set in room temp (25)
one set on the 3d printer heated bad (55)

on the left is the heated one, on the right is the room temp

Heated one had a wood failor which is the optimal result, but there is a spot on the corner where the lamination failed, how weird is that

Anyway, The Epoxy is probably the problem doesn't cure well enough in room temp or something