Recycle Your Mattress
Polyurethane chemical recycling
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Welcome back to this month’s issue focused on circular materials and green chemistry. I’ve got a new sponsor this month for the newsletter too, which is exciting for the formulators out there.
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When it comes to polyurethanes there are only a few big system houses that have real influence on the market. I use the term system house to refer to chemical companies that are vertically integrated into making their own polyols and isocyanates as well as being able to supply starting and/or finished formulations to their customers. There are only four global vertically integrated system houses and three of them are currently working on methodologies to recycle flexible polyurethane foam mattresses.
In the last ten years there has been an explosion of direct to consumer mattress companies such as Casper, Purple, Leesa, Tuft and Needle, and Avocado to name a few. Almost all of these mattresses use foam of some sort as a cushion and the most popular and prevalent foam being used right now is polyurethane (yes, latex is used too, but it’s not as prevalent). To make any commercial scale polyurethane it’s a reaction between a polyol and a diisocyanate. A polyol for a flexible mattress is often something like an ethoxylated sugar which we get by reacting a sugar with ethylene oxide. A diisocyanate could be something like methylene diphenyl diisocyanate, which we get by reacting aniline with formaldehyde and then phosgene.
The chemistry of a polyurethane reaction is really just the hydroxyl (-OH) group reacting with an isocyanate (-C=N=O) to make a urethane. The polyols often have reactive functionality sites of more than two for flexible foams. If this all feels somewhat complex, it’s because it is, but the circularity research into polyurethane raw material recovery isn’t going to make sense unless you can point a polyol out of a line-up of molecules. The diol in the picture below (ethylene glycol) is the polyol in making the linear polyurethane depicted.
There is a huge selection of polyols and diisocyanates available for chemists to formulate with and there are more ingredients needed to make polyurethane foams such as surfactants, blowing agents, and catalysts to name a few. Figuring out an optimum formulation for specific design elements of the mattress such as the firmness, enabling air flow, support, and dimensional stability is often referred to as both an art and a science. Each company likely has formulators on staff or they have contracted out their formulations to a system house or a specialty formulator like Troy Polymers. Further, because these mattresses are flexible foams that are essentially a lot of air they are able to be compressed down into boxes that can be shipped directly to consumers.
Even Mattresses Die
The issue with these mattresses is that they only last about 8-12 years. Casper, perhaps the OG of direct to consumer foam mattresses, indicates that their mattresses last up to 12 years. Once consumers are finished with their mattresses, they are often just landfilled or incinerated, because who wants to reuse someone’s used mattress?
The big polyurethane system houses, I think, are attempting to get out ahead of a potential future problem of “mattress waste,” even though conventional mattress technology is also wasteful. The chemical and synthetic polymers industry has been battling this notion that they are polluters (they are, but we all are if we are honest with ourselves), but with the right amount and type of innovation perhaps we can turn our trash back into raw materials to make the stuff we want. If we view this from a waste to raw materials lens it sounds and looks great, but I wonder about energy consumption and transport logistics for used mattresses (it’s just so oddly specific).
Polyurethanes are not considered “commodity” polymers in anyway despite the market share and prevalence of polyurethanes is huge. I would instead consider them in a “commoditized” specialty category in that there is still value in formulation and innovation, but price ultimately will matter just as much as performance. This is why you can go buy a foam mattress that will be really decent for about $600 and have it shipped directly to your door (or maybe the DTC mattress companies just want to lose money in an effort to gain market share).
I’ve never actually bought a mattress that didn’t come to my door, but I do remember my Dad picking one up in his pick-up truck from a store once. The idea of having to drive a truck or strapping a mattress to the top of your car and driving down a highway with it flapping in the wind seems kind of crazy in 2022. If you don’t have a car are you just supposed to go rent a truck or car to get a new bed?
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Chemical Recycling Of Polyurethanes
Most of these recycling programs have focused on using other chemicals to recycle the polyurethanes. This technique is broadly known as chemical recycling and it has been seeing success in the rPET space. While PET and polyurethanes are very different I think the technique is still going to be completely reliant on reversing or breaking the urethane bond. Actually, rPET derivatives that chain terminate with hydroxyl groups that are relatively small are often used in rigid fire resistant polyurethane foam, the stuff used for construction, but that’s a post for another day.
BASF
The German chemical giant appears to be focusing on polyol recovery with their chemical recycling program. Their goal is ultimately to obtain raw material used to make polyurethane mattresses that have the same quality as a virgin raw material. The company believes that by isolating the polyol from the mattress they can produce a new foam with a significantly lower carbon footprint. If you want to learn more about BASF’s process you can go here. The diagram above is how we get the circularity, but I think it’s a bit misleading.
Covestro
Polyurethanes were actually invented by Otto Bayer, the guy that founded a chemical company called Bayer (creative, I know). Covestro was the materials division of Bayer and was spun out years ago and has been doing just fine ever since.
Covestro is doing something similar to BASF with their PUReSmart project that they are coordinating with European polyurethane specialist Recticel. They are also trying to isolate the polyol from flexible polyurethane mattresses and they even have an operational pilot plant running that can take in polyurethane foam and push out polyol to the other side.
In addition to being able to turn flexible mattress foam back into polyol Covestro partnered with Redwave to develop a sorting solution on polyurethane foam. This sorting software (and I’m guessing chemical analysis too) enables sorting of polyurethane foam and ultimately helps identify foam that can be recycled. This is because talented formulators might be able to make two foam mattresses with similar properties using very different raw materials or maybe someone threw in some rigid polyurethane foam into the foam dumpster?
This type of sorting plus chemical recycling is the type of technology we need for all synthetic materials where the end of life question is being asked and we need to figure out what is what.
Dow
The US commodity materials and chemicals giant Dow is also attempting polyurethane mattress recycling through their RENUVA program. They are also trying to isolate the polyols used in foam mattresses. Their plant in France once operational will be able to recycle about 200,000 mattresses per year and according to Covestro each mattress is about 15-20 kilograms in weight. This means the Dow plant will be able to process about 6.6-8.8 million pounds of mattresses every year. Sounds like a lot, but I suspect it will be a drop in the bucket of how much foam is being produced yearly.
You can watch a technical Q&A with Dow here: https://videos.dow.com/view/M26066
I Still Have Questions
As Dow, Covestro, and BASF build out their capabilities and production capacity we might actually be able to assign a true value to an old polyurethane mattress. Further, if successful in these ventures we may be able to witness polyurethane mattresses become more sustainable from a material re-use perspective, but are there real benefits that can be shown in reducing energy and transportation costs?
I’m curious as to how the economics of this will work for these companies and what their co-products are once the process is finished?
What happens to all of the reacted isocyanate that was once bonded to the polyol?
What is the price differential between a recycled polyol versus a virgin polyol and what are the economics of actually sourcing viable polyurethane mattresses?
For normal people I think in the future we can expect more marketing messages getting pushed to us about how one brand of mattress uses recycled materials from old mattresses. The idea of buying a mattress with recycled content to alleviate our consumption guilt will become prevalent. Remember that our global economic model is based on consumption and the consumption powers everything we rely on in this modern world.
Anyone from Covestro, BASF, or Dow want to talk about this in-depth? Let me know in the comments or reach out via email or DM me on Twitter @tpolymerist
The biggest problem recycle faces is not technology (this is not unexpected), it is supply chain. Getting the tons of waste from people's houses to a large recycling facility is an expensive and cumbersome challenge. Creating the concept that the old mattress has a "value" is a wrong idea, it has a cost, much like with batteries and tires these mattresses need to have a recycle fee attached to the price of sale, the central fund used then to pay for the logistics.
A quick thought exercise, how much would you have to be paid to take your mattress to your local "large recycle facility"... the value of the 20kg of recycled materials maybe after processing (that includes the processing cost) is $20 -$40...If it was much more, mattresses would be very expensive.
It is something we need to do, we just need a good business model...think of a $1,000 mattress needing a $100 recycle fee in the sale price. It could work
I remember attending some seminars about Niaga when I was at DSM and thinking similar things.
The logistics are *hard*. A foam mattress typically absorbs a substantial amount of water during use and by the end of its life may weigh up to 40% *more* than when new. I feel like in large metro areas there need to be receiving facilities that dramatically simplify logistics by dehydrating mattresses, chopping them up, and vacuum sealing them in a transportation friendly manner. That also simplifies pickup of recycling feedstock.
Roman is absolutely right that a mattress must be considered a feedstock for an end product rather than a valuable asset. That kind of focus allows one to innovate realistic path to value generation rather than wishful thinking and green washing/marketing proposals.
The other question I have is the energy and %recovery state of the art in reversing a polyurethane reaction. It is *much* easier to recycle rPET because 1) it's not cross-linked, 2) polyesters can undergo simple hydrolysis while polyurethanes form a much more stable bond.
I've seen "green" feedstocks offered on the market at 2x the price with 1/4 the supply chain certainty (which is already fraught). As much as I want to make my products as green as possible, doing so to the maximum possible extent is both fiscally and strategically irresponsible. You cannot create a sustainable product with an unsustainable commitment to your customers on quality and supply. Perhaps the polyol feedstocks can be blended into commodity feedstocks at quality and served as a product that's not distinguished, if they can get their marketeers and publicity folks to be ok with that.