Polyurethane Adhesion

How thick is the sheet?

How is it made?

Cast between sheets of metal?

How large will the largest single piece applied to a wall be?

Define "sponge rubber" what type of material is it?

What surfaces will you be applying it to? metal, paint,wallboard

That's enough to start

_{How thick is the sheet?}

3/32"

_{How is it made?}

MOnkeys? (not sure)

_{Cast between sheets of metal?}

uhhh... see above?

_{How large will the largest single piece applied to a wall be?}

I only need the rubber to adhere to the urethane.

_{Define "sponge rubber" what type of material is it?}

natural rubber is all I know now. Have a call in to the supplier for more data.

_{What surfaces will you be applying it to? metal, paint,wallboard}

Only the urethane. (once in place it is mounted using hardware if used as a wall application)

_{That's enough to start}

Thanks LynLynch

OK, so I've made this more complicated than it needs to be.

Where does the bond fail?

If it fails on the PU surface, glue sticks to sponge and comes off, adhesive failure. If the glue comes apart, that's good. If the sponge fails, that's OK, too because you have a good bond.

The shiny surface concerns me. Does the surface of the PU sheet feel slippery?

This is supplied to you? In what form? Roll, sheet?

For good adhesion, you need lots of "tooth" in the substrate, mechanical roughness, and NO CONTAMINATES on that surface.

Do you know who the producer of the polyurethane is (ie Deerfield, Huntsman, etc)? Did you mix the two parts or did your sheet come already made? If you mixed the two parts and have any left, you could use that as your adhesive.

you should ask the guys at Sika. They are the adhesion experts. check out there website... www.sika.com and go to the industry division...

I hope this is usefull.

regards

I suspect the main problem is the gloss on your polyurethane sheet.

Experiment on a small piece with solvents to remove the gloss from the polyurethane surface.

Try acetone first, but you will probably need something more aggressive like MEK or methylene chloride.

After you have softened the surface, it is likely that a normal contact adhesive or rubber cement will work.

If this isn't satisfactory, try the numerous polyurethane based adhesives.

Good luck

Are you able to make small batches of an adhesive yourself? Can you obtain gallon samples of saturated polyesters and MDI? You should be able to make a very good industrial adhesive from components such as a 2,000 MW hexanediol adipate, 1,4-BDO and/or DMPA, plus MDI. Preferably at 60 % solids in solvent, toluene, MEK, butyl acetate, whichever you prefer. Try to keep the NCO/OH around 1.6 to 1.8 and cook for 1 1/2 hours at 80 - 85 C. If you can run % NCO determinations, even better. I make a PU medical primer that essentially sticks anything to anything, but it is tailored to the medical market, and therefore expensive. An ideal adhesive that performs extremely well would be diamine-extended PU prepol, as above. Cook the prepol in toluene, and extend in a dry toluene - ethanol (or isopropanol) blend. Be sure the final pH is 7.1 to 8, or the product may gel on standing.

THank you all for your help.

So here is what we have done:

At about 40minutes into cure we are crosshatching our pour with a wire brush. The type you would clean the hull of a ship with - very, very stiff.

Our sheet rubber (the 2nd part) is getting an acetone mist and a t-shirt towel wipe.

I am using Dri-Tac 7500 a one part urethane (also a "green" product) to adhere the sheet rubber to our poured urethane backing

Results are at about 90% acceptable right now. I think the remaining 10% will be worked out through process refinement.

Thanks to all.

Good luck, sounds like you have it under control.

Could you post a picture of the finished item?

Yes and no. There is a problem with non-disclosure.

Never mind.

Good luck

I sent you a PM.

How's Mesa? I spent a little while in the Chandler/Mesa area. Working on an Intel project. Ultra High Purity (UHP) aqueous chem, H2O and gaseous chems. Nice area.

Assuming that the urethane does not bond too rapidly

Also assume 2pack urethane is solvent free.

- use it to make the bond - put a thin coat on the surface of the cured material and then put the backing on otherwise cast straight onto the urethane.

That was the original idea. The problem was removing the oils from the natural rubber w/out saturation of the rubber by the rinsing agent.

This has been resolved by use of a very fine mist of acetone and a towel wipe.

thanks

Sounds like you are winning - I did not get the base rubber bit!. It might help to add a small amount of xylene to the acetone wash this will give a slight tack to the rubber which could help. Problem with acetone it evaporates too quickly and so leaves dissolved solids behind - any idea what the surface contaminant is ? How does a good water based wetting agent (teepol) function?

Thanks for the xylene suggestion. I believe the contaminants are oils left behind from the manufacturing process.

The people you need to speak to in regards to that kind problem would be CQMS Razer in Australia. They are poly gurus and have helped us more than once with trouble shooting problems like this.

Your application is an interior design; so I suggest you to use rubber adhesive used for car tire puncture; to my exprerience this is best solution and its cost is very neglible. I sell polyurethane sheets in bulk but these are technical grade and used for glass surface polishing. Before apllying solution you should make the polyurethan soft by diping in warm water for few minutes (this depends on various types of polyurethanes)

Gorillia glue

does not work. Tried it.

Have you tried to " ETCH " the area where you want to apply the rubber ? Etch will remove the shine and allow glues to work.

Yeah. What did you have in mind. Am open to suggestions.

I wish I knew how you wanted to apply the rubber. I solid sheet or only small sections. If a sold sheet then some type of pass thru with Etch applied only to the bottom. For small sections or DOTS then a press and lift process would work.

Saftey Equipment is a must or possible robotic for the press and lift.

Etch is a nasty material to use.

Etch your material the same way they do computer boards.