Green Converting: Recycled Roll Coverings

How do you make a measurable impact on sustainability in an industry such as converting? In actuality, converters don't have a tremendous say in the products their customers want them to produce.

As equipment suppliers, how can we make a difference? We're told what type of covering to put on a roller, and we do it. Sure, we make recommendations, but by and large, there are probably 20 roll coverings that are being used in industry today.

Now, after nearly two years of laboratory testing, a new sustainable roll covering has been developed. Some of the used material that is taken off when rollers are recovered can be recycled by this new process.

What Is Sustainability?

A few years ago, I would have said sustainability is playing a round of golf and using the same ball the whole round. For this article, let's use the Sustainable Packaging Coalition's definition of sustainable packaging:

  • Is beneficial, safe, and healthy for individuals and communities throughout its life cycle
  • Meets market criteria for performance and cost
  • Is sourced, manufactured, transported, and recycled using renewable energy
  • Optimizes the use of renewable or recycled source materials
  • Is manufactured using clean production techniques and best practices
  • Is made of materials healthy in all probable end-of-life scenarios
  • Is physically designed to optimize materials and energy
  • Is effectively recovered and utilized in biological and/or industrial closed loop cycles

This summer we witnessed a huge oil spill in the Gulf of Mexico. Everyone says our dependence on oil is ridiculous; “they” need to invent alternate forms of transportation; when is solar energy development going to take hold?; what's taking “them” so long? We need to keep our eyes open and innovate.

In the converting industry, some rolls that are being processed take as much as 2,000 lb of rubber. A series of 200 small rolls each can take 20 lb.

The problem with rubber and cast polyurethane is that once rubber is changed from a raw or uncured state and cast polyurethane has been catalyzed, the process can't be reversed. This is just like the large piles of used tires that have become a huge problem ever since the advent of the automobile.

If tire manufacturers could get the rubber back into its pre-vulcanized state, they would, because it could be used again to make new tires or other products. But rubber chemistry won't allow for that.

What's New in Roll Coverings?

Most of the approximately 20 rubber compounds used in the industrial roller industry were developed originally during World War II by Goodrich, Goodyear, and DuPont. Those are nitrile, Hypalon, silicone, ethylene propylene diene monomer (epdm), neoprene, carboxylated nitrile, styrene-butadiene rubber (SBR), natural rubber, urethane, and elastomers like Viton. There isn't much else. Until now.

In the next 20 years, all of these vulcanate compounds will be replaced with formulations that spin off from thermal plastics, such as the new compound that has been developed. There are thousands of chemistries in thermal plastics, not just the common 20 being used today in rubber.

Why does it work? The reason is that thermal plastic can be remelted and used again. Because it can melt, applications that have higher operating temperatures won't allow its use, but there are millions of other uses that operate at, let's say, under 125-150 deg F.

The new product is tougher than tough, making it perfect for high load. It has better abrasion resistance than anything put on a roller today, and cut resistance is very important in the converting of substrates. How often has your roll worn out because the edge of the substrate you're converting cuts into the rubber? This is especially common when changing web widths. Every time you go from narrow to wide, you have to change the roller. If I had a dime for every time I heard that….

Imagine those applications in which large winding or nip rolls require 700 lb of rubber. That covering is then discarded in a landfill. Now as much as 100% of that material can be saved by removing it carefully, testing it for foreign contaminants and physical properties in a lab, deciding which can be reused in a roll covering, reapplying it with a mixture of virgin material, and then using the balance for other products in other markets. We can get many more uses out of it as a roll covering without suffering any loss to the physical properties it needs to perform in its application. If it doesn't pass the rigorous testing required to reuse it as a roll cover, it can be sold for less exacting uses.

Does it save costs? You bet! Although there are costs for the careful machined removal of the product from the roller core and the testing and reformulating, in some cases 40% of the compound cost can be saved, which is a big percentage of the roller cost.

New processes also are being developed to bring down the reprocessing costs — not to mention how good it feels to be adding to the sustainability movement by eliminating and delaying the amount of material ending up in landfills. Putting the waste in landfills costs money, too.

Currently, developments are being made in new products to manufacture once the thermoplastic polyurethane (TPU) elastomer is no longer viable for use as a roller covering. We all want to recycle everything we can. Numerous rolls have been tested in the field without one adverse effect to roll performance. Further testing is being done to find new compounds for other industries.

With these developments, future generations will not know any other way but to use sustainable products. Going forward, I would measure sustainability like I would success: Success is very rarely one defining event but merely the piling up of little small successes. That is how we are going to become a more sustainable world. Little advantages will one day solve a large problem like an oil spill in Louisiana.

Matthew Menges is president of Menges Roller Co., Wauconda, IL, a roll covering and fabrication specialist manufacturing roller cores and coverings to 48-in. dia and 30 ft in length. Contact him at 847-487-8877; mmenges@mengesroller.com.

The views and opinions expressed in Technical Reports are those of the author(s), not those of the editors of PFFC. Please address comments to the author(s).

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