Pure TPU as adhesive

[naas]

I think it should be possible to substitute the aquaseal/seamgrip with pure TPU. If it works, i thing this might be a more elegant solution. There are many options available:

Tape : https://www.aliexpress.com/snapshot/0.html?orderId=91104071137854&productId=32606089136

Sheets: https://www.alibaba.com/product-detail/TPU-hot-melt-glue-sheets_60337645822.html

3D printer filament: https://www.ebay.com/itm/SainSmart-50g-Flexible-TPU-1-75mm-Filament-for-3D-Printing-Gift-Pack/352183376113?hash=item51ffc3d8f1:m:mBYNmRJdw275pu-aSFzyQIA

This filament could be applied with a “3d printing pen”: https://www.banggood.com/2nd-Generation-3D-Printing-Drawing-Pen-3x-1_75mm-ABS-Filament-EU-Standard-Plug-Power-Adapter-Kit-p-1158476.html?rmmds=cart_middle_products&cur_warehouse=CN

 

 

 

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[harald]

It might interest you that a similar technique was used in olden times for field repairs of wooden folding Kayaks with a PVC fabric skin: PVC was scraped with a heated knife from PVC patches (or fabric they carried for that purpose) and then the hot PVC was smeared with the hot knife on the area to be patched. Requires obviously some skill.

[droller]

This won’t help with having elegant looking seams, but you can use the TPU from the fabric to make patches.  Place a strip of TPU coated fabric with the TPU side down on some parchment paper.  Put on some leather gloves.  Heat the nylon side twice as long as you would for normal sealing.  While holding the fabric strip, raise your iron onto its edge at a 45 degree angle and push away with the iron while pulling the strip toward you.  The TPU should bunch up at the edge of the fabric, or stick to your iron, remove it while wearing your gloves and set it aside on a clean piece of parchment paper.  Continue this process until you have enough for a patch.  Place all the TPU chunks or bits together on the parchment paper.  You will need some silicone tape, I have been using “Sharkbite” brand, it is 2 inches wide, and it is translucent.  Silicone tape is mostly used for quick fix plumbing problems.  It only sticks to itself, and it can withstand heat up to 500 degrees F.  Lay your silicone tape over the TPU bits, then use your iron to melt it all together, this will take about twice as long as your normal sealing time.  Once you remove the iron hold down the silicone tape and use your silicone roller to flatten the TPU patch.  To apply the patch simply put it where it is needed, cover it with the silicone tape and press with the iron, again it will take longer to heat through the silicone tape and melt the TPU.  Use your silicone roller to ensure it has melted together.  It will look shiny, but I have had no problems with the pinhole leaks that I have repaired with this method. I have even used it on some of the corners where the seams meet the floor with good results.  The TPU will melt to the nylon side of the seam as well which I think is a slightly better repair than Aquaseal or Seam Grip.

Sorry that was so long winded, and not much help to the original poster.  But since the subject was TPU I thought it might help someone.

[Matt (Admin)]

Very creative tip – thanks for posting! I can see this being especially useful for spots where I accidentally damage the TPU on the tube fabric. Cheers!

[harald]

I got a sample of a transparent TPU sheet from a German shop: https://www.diekleinewerft.de/TPU-Folie-152cm-breit-038mm-dick-semitransaprent

(They also have TPU tubes for making bladders.)

Unfortunately, this TPU has a much higher melting point than Matt’s fabrics. Since the material has not a fabric backing it warps if its heated and the warps stay if it cools down.

So in order to use this as a sort of patch you would want a TPU with melting point similar to your fabric TPU, heat it uniformally until it melts then press down until it recristallizes to prevent warping. In my opinion there’s no upside compared to using a single coated TPU fabric as a patch.

In theory one could try to melt this TPU until it liquefies and then paint it piping hot. In this case the high melting point of this material might be an advantage since it would easily bond to Matt’s TPU.

[Matt (Admin)]

Interesting! I got some samples of TPU sheets too, but I haven’t had time to experiment with them yet. In a way, it’s a “solution in search of a problem,” but when we find that problem it will be an elegant fix. A higher melting temperature will make it difficult to use though.

[Bruce]

I tried several different heat sealing tapes. Bonds to the PU coating was unsatisfactory so I gave up. I was also unable to determine if the film of tape chemically matched the TPU coating. My understanding is that plastic welding and bonding only works between two identical or compatible plastics.

[naas]

I just tried the VHB tape,

If you clamp it momentaraly between two pieces of wood, it bonds very good to the non coated side.  On the TPU coated side it doen’t stick very well.

[Matt (Admin)]

Thanks Naas, that’s good to know! It’s interesting that you have to clamp it. Do you think it would work on a flat surface if you pressed it with a roller or placed weights on top, or does it need to be clamped?

[naas]

i don’t see why rolling wouldn’t work just as well.

[Paul]

Has anyone tried the 3m VHB tape?  sea to summit sells these self adhesive lash points with 3m tape on them.  apparently this stuff bonds to anything, the smooth surface of packraft fabrics would require some surface prep to increase bond strength.  3m built a scooter using only tape as fasteners

[Matt (Admin)]

Hi Naas, I tried using TPU tape and couldn’t get it to form a strong bond with the fabric so I gave up on the idea, but if you figure out a method that works, please let us know!

[Author]

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