Totally clear adhesive?

[Erik King]

Hi All,

I'm putting together the final approval samples for some address plaques we designed that are composed of three different layers of clear (laser cut) acrylic. The issue I am having is that the base piece needs to be securely glued/welded/mounted to the middle piece which mounts above it. But here's the tricky part - the middle piece is translucent (it's clear acrylic with a digitally printed pattern on it's face) - so, when you use a standard solvent welding technique you see the random glue residue thru the face of the middle piece, and that's not acceptable.

After trying the normal "hypo" method of application, I than tried to coat the entire piece with both the thin and thick versions of weld-on, but neither could be successfully spread evenly and then mounted quickly enough to work.

I also tried 3M "ADA type" adhesive file, but it does not stay on in a smooth layer and is not optically clear, so it shows as well. Additionally, it is not rated for outdoor use, and these are going to be outdoors.

The only other idea I have (as yet untried) is to find an optically clear mounting adhesive that is outdoor rated, apply it with a laminator to the back of the printed acrylic sheet, and than laser it with the adhesive in place. Not ideal - it's a lot of extra steps and unlikely to bond with no flaws, but may be worth a try, unless...

...someone in the world of the Creek has a better idea?

I'd sure appreciate any suggestions or solutions ya' all know of that give an optically clear bond of two pieces of acrylic.

Thanks!

[Randy Walker]

Hi Erik
Have you tried epoxy? There are several that are very clear and good for outdoor usage. I don't know about compatability with the plastic you are using but you can work that out. As far as getting air bubles out of the midle of two pieces, a vaccuum chamber (not a vac press) is about the only thing I know of that will do that. You can most likely find instructions for a vaccuum chamber in Google or on You Tube, or maybe another SMCer. I hope this helps.http://www.sawmillcreek.org/images/icons/icon14.gif

[Rodne Gold]

The secret is how you apply clear adhesives when bonding 2 flat panels , the problem is entrapped air pockets and bubbles , the adhesive has to be applied so that these can escape. We find an X pattern or a * pattern is best.

[Joe Pelonio]

As Rodne said, Weldon can be used for a totally clear application with practice.

The 3m laminating films do not come out clear because the adhesive is sort of lumpy. They do have a clear VHB tape (9410) that works a lot better.
I have some here, it's 40 mil, a red carrier. Not cheap, 3/4" was about $60 for 36 yards. I think they also have it in a 20 mil.

[Erik King]

We've tried most of the variations on VHB, etc and not had good results. I don't hthink any kind of hand applied film/tape will be able to be put down without flaws <sigh>.

There is an optically clear laminator applied adhesive that I am pretty sure will work (in the olden days before we had a flatbed printer we used it in our commercial sign business to affix translucent printed film to the second surface of clear acrylic sign faces). I just hate to use it because it is so labor intensive, and creates a lot of waste during assembly as it is very "grabby" and prone to collect dust & flaws.

I was hoping maybe someone would have seen a totally clear adhesive that we could cover the entire surface with and than bond them together. A standard solvent weld will work - the weldon is a great solution except for the fact that I can see through the face and tell where it is (and is not) applied. I have not seen such a thing, but I hope it exists!

My latest thought is to call Weld-on, and Lord's Adhesives and see what suggestions they have for non-mainline products...

If anyone thinks of anything else I'd love to hear about!

Thanks again,

[Richard Rumancik]

Have you looked at UV-activated acrylic adhesives? (Acrylic here means the adhesive technology, not the substrate. Acrylic adhesives can be used on many things besides acrylic.) Perhaps Loctite has something that would work. Since in your application you can see the adhesive, the UV source can cure it. (It won't work for opaque substrates.) The UV lamps can be expensive (and the adhesives probably are as well) but it might be the only thing that is reliable. You might be able to make a UV exposure lamp or buy one used.

[Angus Hines]

Ultra Sonic bonding techniques my work but finding somebody and then the $$$$

[art baylor]

It might be worth contacting an acrylic fabricator (usually a medium to large distributor with manufacturing capability) to see what they might charge to do this for you. They have more experience and access to better stuff than you do. A company I used to work for years ago used to laminate large sheets of 1 1/2 inch plex together for the front panels on glove boxes.

Art

[Rodne Gold]

There is a system Degussa liscences and sells to laminate thich pex or bond sheets without ANY glues , basically it heats the 2 surfaces and "melts" em together (along with anything flat you want to embed in between em)
It is hellishly expensive and of limited useage.
Most decent pex glues , like Tensol will work a treat.
Apart from air bubble entrapment and placement of the glue in a pattern that will stop this , there are other issues , like dust and specks.
Pex has a huge static charge and large areas are almost impossible to clean adequately apart from which the static does the glues no favours either when 2 pieces come into contact with each other , the only way to cure this or indeed to work with pex if you glueing , sawing or bending is to use an ionizer attached to an air feed.
Blowing ionized air over pex removes the charge instantly and any pex fab shop worth its salt will have one of these.

[Bruce Larson]

We use a UV curing adhesive from Photobrasive for glass and marble that is totally transparent and permanent. It needs a UV light to cure, and we haven't trried it on acrylic but it works great on what we have used it for.

[Erik King]

Any case it is of help to others, I wanted to let everyone know that I talked with the manufacturer of Weld-On today and found that they do have a couple products that will work in this application.

We normally use #3 and #16 in our sign work, but #3 is both too thin and too fast setting for this, and #16 is too thick to spread evenly.

The tech support folks suggested trying #4, which is like #3 but slower to set and a bit thicker. Or, if this does not work they suggest using #40 which is specifically made for this application but is a more complicated two-part formula.

So, looks like I'm set to go. Hope this info comes in handy for other Creeker's as well!

[Larry Bratton]

With #40 I found it to be extremely difficult to work with. If I am not mistaken, it is a two part, extremely fast drying epoxy. It requires an expensive mixer gun and unless care is taken, you will find yourself out of the mixer tips very quickly. I don't recall it being particularly clear either. It is a good epoxy, but not suggested unless your planning on using the whole tube on larger pieces.

[Gary Hair]

You can do this with UV cure epoxy. I have a customer project that involves gluing two discs together, one is 9" the other is 6" in diameter. I very carefully spread the epoxy on the smaller disc, place it carefully on top of the larger one and turn on the uv light. I made the light box myself, it is 3 dual tube flourescent fixtures with blacklight bulbs. It takes a bit for the epoxy to cure, but it works fine so far. I am using DC7155 from epoxies dot com - same stuff that ultradome sells for over twice the price... 1 Gallon was about $180 vs $46 per pint.

Gary

[Richard Rumancik]

I have a really old issue of A&E and there is an ad from a company called Norland Products Inc. (www.norlandprod.com (http://www.norlandprod.com))

Their ad refers to UV cure adhesives aimed at the awards industry. Perhaps you could contact them and ask what they would recommend. On their website they show some examples of awards being bonded with UV adhesive.

I would tend to avoid two-part adhesives if possible as you can waste a lot. The ones that require mixer nozzles are fine for a production line, but if you need to waste $5.00 worth of adhesive just to fill the mixing nozzle it can get expensive when you just need to bond a few items.

Another possibility for UV optical adhesives is Dymax
http://www.dymax.com/products/plastic/index.php

[Bob Davis]

How about a clear double-sided tape? Lots of hits for that search on Google, and it's relatively cheap.

[Rodne Gold]

Its also extremely visible, there is a water clear double sided window mounting film for graphics inside of windows , available from most vinyl sign suppliers but its exceedingly expensive.

[Richard Rumancik]

I don't think there is any solution for this that will not be somewhat expensive. However if it were me I would go with something that could yield 99% or at least had some chance of being reworkable. Many options give you one chance at it.

There are some UV adhesives for glass that give you a second chance; it requires soaking in a solvent for 12-24 hours but I doubt any plastics would tolerate that. The thing that makes UV look attractive is that you have lots of time to assemble, fixture, get out bubbles, etc. Once that is done, you can initiate the cure. Conceptually that sounds good to me although I have not used UV adhesives for what I am doing.

[Martin Boekers]

Optical tape is available from MACTAC or SEAL CODA you can do a search on these. These are extensivly used in the commercial photo industry for "laminating images to plex. If you have a larger commercial photo lab in your area you may be able to talk them out of some scrape to test with.

Tip on apply after you aplly the first surface burninsh well with a nylon or plastic burnisher. this will cut down on bubbles in the application.


Marty