Polypropylene Adhesive

I must apologise, but cannot advise an adhesive for you, but am interested in some details, since production of "thousands" might make an alternative method more suitable.

What size are the pieces?

Does the box also have a bottom?

Does the box also have a top?

How thick are the wall sections?

Does it need to be water tight? (What does it have to contain?)

For "thousands" then it should be attractive to mould the item complete (size limitiations) rather than the challenges, jigs and fixtures for gluing.

If they are larger, then ultrasonic welding, vibration welding or even "clipping" them together could be suitable fastening methods.

As JaE suggested, you might seriously consider ultrasonic (friction) welding.

Search CR4, I'm sure we've had this Q before...however I concur with the other guys. If you are making a lot, design out the need for adhesive.
Del

Hi, I'am a certified plastic welder and very familiar with all plastics and the different ways to join them. Polypropylene can only be welded, I have never found an adhesive that will work with polypro. Welding would be your only option. Jim

Depends on the structural requirements of the objects.

There are adhesives which will do an adequate job, depending on the requirements.

Environment is critical.

Why don't you make it a snap fit, and be done with it?

I just ordered some 3M 1357 contact adhesive for another purpose. I have some polypropylene scrap sheets. Sounds like an interesting experiment.

Ed Weldon

I have to agree with the other posters: Typically adhesion to polypropylene is not good with most adhesives. It depends on your application. If you only need to lightly hold the parts together, you may be able to use some contact cements. If you need more than that you will have to look elsewhere.

A few things to keep in mind. Roughing up the surfaces to be glued should help-giving the mating surfaces more surface energy typically gives a greater likelihood of bonding. Sometimes a plastic primer can be used to help plastics adhesion. As some of the other posters mentioned, interlocking features like snap-fits, etc. can be used as a redundant joining mechanism.

We have used Ultrasonic welding for numerous plastic bonding applications, and have had the most success with that. This can be done in numerous ways, one of the most convenient being with a hand-held pistol set-up.

Another thing we have used frequently are 3M VHB tapes. These pressure-activated "Very High Bond" tapes have different characteristics depending on the type you use, but I believe one can be found for use with Polypropylene.

Good Luck & consider designing in snap-fits or weld features.

Maybe he just wants to know what kind of adhesive to attach a label? Buy the self stick, the ones you lick taste yucky!

Coming from a company where we had to glue to polypro (yuk!), I can tell you that adhesives are NOT a "first choice." If you HAVE to use glue (though I do recommend welding of some sort) then:

1. Roughen the surface

2. Use a surface treatment like flame or plasma treating

Polypro has an incredibly low surface energy; for good adhesion you want the surface energy to be higher than the surface tension in the adhesive liquid. Flame or plasma treatment can do this.

David Hunt, PE

By purest coincidence, Assembly Magazine (Feb 2009) has an article on plasma treatment for adhesion.

http://www.assemblymag.com/Articles/Feature_Article/BNP_GUID_9-5-2006_A_10000000000000514160

David Hunt, PE

davidhunt@outdrs.net