WPC100M and WPC100M-PP Shrink Sleeves
As you may know (if you're reading this blog) in the world of pipeline coatings, polypropylene is a little bit of a different animal. Yes, it offers improved abrasion resistance and heat aging qualities over some polyethylenes....but it also presents a new set of challenges. Polypropylene can be very difficult to stick to! When you're trying to form a seal against a pipeline coating and a bare steel field joint...being able to bond to those two surfaces (factory applied coating and steel) is pretty high up on the list of "must haves."
For that reason, as polypropylene (and three layer polypropylene) have become more commonly selected factory applied pipeline coatings, the field joint coating industry has had to adjust accordingly. Well, that's not entirely true. Covalence (formerly Raychem) has been developing adhesive sealants that bond well to PP for many, many years. One of the products that has been installed most often on PP coated pipe is our WPC100M product.
Historically, it has always been known (within Raychem circles) that the WPC100M does an excellent job with bonding to PP. The issue was - for whatever reason - the "industry" back in the late 1990's wanted a product that was SPECIALLY DESIGNED for use on PP coated lines. This didn't make any sense! We already had a perfectly good product with a proven history and a flawless track record. Why develop something else? So - a data sheet labeled "WPC100M-PP" was created along with a customized installation guide. As a result, about a decade ago, many specs were written with the label WPC100M-PP which caused some confusion.
Now, fast forward a few years and Covalence (formerly Raychem - but at the time of this point in the story they were called Berry CPG I think) invents a heat shrinkable backing that is some percentage polypropylene (I don't honestly know how much). At that time - they take this newly created backing and coat it with the same proven WPC100M adhesive that has been used before. We now have our third iteration of a WPC100M material that works with PP (original WPC100M; renamed WPC100M-PP and WPC100M-PP with PP component in backing). And...more specs are written.
As you may know, many, many of the performance criteria for a shrink sleeve are dependent on the adhesive. Things like softening point; cathodic disbondment, peel, shear, penetration resistance, heat aging, and others are all (largely) determined by the sealant material.
At the same time, there are a number of criteria determined primarily by the backing material. These are water moisture vapor transmission, elongation, abrasion resistance, penetration resistance (again) and others. So, the PP backing does improve performance in some areas slightly over the PE (actually a modified polyolefin) backing. The question becomes -- what factors are important to you --- and how important are things like cost and delivery? (we stock the WPC100M in large quantities...we do not currently stock the WPC100M-PP material). Give us a call - let's discuss this.