Unlocking Potential: Supercritical Foaming Technology in Modern Footwear Design
OrthoLiteIt’s fast. It has a lower environmental impact. It’s solvent free. It’s safer for the people making it. It produces a fully customizable, lightweight, durable, and comfortable foam.
It is supercritical foaming. And it may be the answer to your footwear design challenges and a step toward more sustainable manufacturing for footwear.
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What is Supercritical Foaming?
Supercritical foaming is a physical foaming process for plastics. Before getting to the benefits of what that means, it’s helpful to understand the alternative: chemical foaming processes.
Chemical plastic foaming is arguably the most common technology used to create footwear foam today. In this process, a chemical foaming agent (a.k.a. blowing agents) is injected into a polymer. When heated together, the chemical foaming agent decomposes and releases gas into the mixture. The gas bubbles create air pockets in the melted polymer to create a foam.
While cheap and very capable at their job, many chemical foaming agents bring along some baggage. Some of it is early in the supply chain during the manufacture of the toxic chemical agents. The rest is usually associated with inhalation risks, carcinogens, and the release of volatile organic chemicals (VOCs) during heating, decomposition, and post-production off-gassing.
[It’s important to note that the chemicals used as foaming agents can vary. We encourage our brand partners to ask their suppliers for qualification and specifications of their safety processes.]
Supercritical foaming (SCF) skips the “chemical” part entirely and injects an inert, nontoxic gas–usually carbon dioxide or nitrogen–directly into the melted polymer. With the right blend of heat, pressure, and mixing, a uniform and high quality foam is the result.
The Comfort and Performance Benefits of Supercritical Foaming
Supercritical foaming creates foam with the following characteristics:
- Lightweight
- Small pore (air pocket) size and uniformity
- Durable comfort
- More stable performance
Lower Environmental Impacts With Supercritical Foaming
The environmental benefits of supercritical foaming stem from eliminating chemical foaming agents from the process.
Lower demand for toxic chemical agents reduces their production, and thereby reduces pollution along the entire supply chain. The associated human health risks of production-related inhalation and long-term exposure hazards are mitigated. Most of the post-production VOC off-gassing associated with chemical foaming is a result of the decomposition of the chemical agents when they’re heated. So associated air quality and breathing quality hazards also mitigated with SCF.
Remember that the overall impact of footwear foam manufactured via supercritical foaming is, once again, also reliant on the polymer, not just the process. For example, even though EVA can be foamed using SCF, the resultant foam still will not be recyclable or offer any other viable end of life solution beyond a landfill.
This is why we chose thermoplastic polyurethane (TPU) for our breakthrough midsole foam, Cirql rTPU30.
Recyclable Cirql rTPU30 Produced Using Supercritical Foaming
The most recent innovation from our sustainable materials division, Cirql, is a fully recyclable midsole foam produced using SCF. Cirql rTPU30 is now available to all footwear brands and T1 manufacturers.
Cirql rTPU30 uses supercritical foaming to create a durable, flexible, and lightweight foam for all types of comfort-forward shoes.
As the “Cirql” name implies, we approached sustainability from a 360-degree-perspective to create this superior midsole foam for brand partners seeking to lower their environmental impacts and move decisively toward their sustainability goals.
Check out a few highlights of Cirql rTPU30:
- Comfort-forward midsole foam
- Produced chemical-free foaming process
- Made from fully recyclable TPU (with responsibilities for deconstruction and take back programs up to brands and consumers)
- Includes 30% recycled TPU and 70% virgin TPU to optimize comfort, performance, and durability
Ask us About Supercritical Foaming and Cirql rTPU30
To understand how supercritical foaming can help your brand move toward its sustainability-related goals and help curb unneeded chemical usage in footwear manufacturing, contact the Cirql team here.
To uplevel your current midsole foam options into comfort-forward, fully recyclable Cirql rTPU30, get in touch with us here.
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