Growing materials: thermoformed ‘grow trays’ molding packaging sustainability

Some companies manufacture packaging materials; others prefer to grow crops. However, two companies have combined the two processes for one purpose: growing sustainable packaging.  

Natural material supplier Ecovative has collaborated with thermoformer Dordan Manufacturing, on the design of new thermoformed grow trays, which are used to hold Ecovative's packaging material consisting of agricultural crop waste and mushroom roots.

Ecovative environmental director Sam Harrington told PlasticsToday the company "literally" grows materials.

Ecovative grows EPS-like packaging material out of agricultural waste utilizing the biology of fungal mycelium to "bind" the fibers together, according to the company.

"We use a living organism, fungal mycelium, to transform lingocellulosic crop wastes (like seed husks and plant stalks) into a chitenous biopolymer," he said. "Today, these materials are being sold as EcoCradle custom molded protective packaging."

While Ecovative first applied this technology to the packaging industry by supplying custom designed protective packaging, it now offers several stock packaging/products such as the recently designed EcoCradle insulated shipping cooler. During the grow process, Ecovative uses thermoformed grow trays that serve as the molds in which its material is formed into the product during a seven-day period.

Chandler Slavin, sustainability coordinator for Dordan, said Ecovative collaborated with Dordan on the design and manufacture of its cooler thermoformed grow trays due to the company's experience applying engineering-based, thermoformed solutions to a variety of custom projects.

Ecovative looked for a standardized tray format to allow for easy and consistent integration into its custom filling and washing stations, according to the company. 

Growing past limitations

The process of thermoforming has several inherent limitations that ultimately can determine how parts are designed.

"In our collaboration with Ecovative, however, it was more so the limitations of their custom processes than our limitations as thermoformers that dictated the final part geometries and functionalities," Slavin said.

For example, thermoformers must consider material thickness or gauge, and Chandler said some of the geometries Ecovative was looking to create pushed the limits of depth of draw in thermoforming; that is, how deep material can be pushed into a cavity without webbing or impacting the integrity of the cavity.

Dordan worked with Ecovative to design parts that optimized depth of draw features, while not compromising overall part performance or functionality through an informed, systems-based approach to total part design.

Also, the cooler grow trays need to have aggressive denest features to allow for ease of integration into Ecovative's filling processes. This feature did present some obstacles for Dordan as far as stripping the parts after conversion was concerned.

Dordan had to investigate different approaches to stripping to allow for the most efficient stripping without compromising shape or structure of the overall part.

Material to grow into

Due to Ecovative's growing process, the type of resin used in the manufacture of its grow trays is PETG, in which the 'G' protects the resin from decomposition through microbial digestion. This was the material specified to Dordan by Ecovative based on its previous trials with thermoformed grow trays and its EcoCradle growing process.

"With any other resin-be it PET or RPET-the mycelium "ate" through the plastic, rendering the grow trays ineffective due to the transmission of air in-and-out of the part in an unregulated manner," Slavin said.

The trays are thermoformed on an in-line, computer-controlled thermoformer.

Finished grow trays

After much exchange of ideas about the requirements of this unique process, Dordan and Ecovative developed a design that allowed for tray rigidity based on the parameters of its processes.

The finished products offer aggressive denesting features and are highly stackable, Slavin said.

Looking similar to TV dinner trays, the grow trays are made with 60-mil PETG, and feature three shallow cavities, along with the Ecovative name and a mushroom-shaped logo imprinted on the lids. The thermoformed grow trays are then shipped to Ecovative to be filled with the various agricultural by-products.

All trays are designed to optimize Ecovative's production processes, which require universal tray geometries of 21 x 21. The trays are engineered to last for at least 100 uses before being recycled.

Future growth plans

Slavin said the company is waiting to see how Ecovative's coolers perform on the market to determine Dordan's next run quantities and to perhaps look into design modifications.

"We are hopeful that consumers will be excited about this alternative to EPS coolers and we look forward to running more cooler grow trays for Ecovative," she said. "We continue to collaborate with Ecovative on the design of their thermoformed grow trays for various custom customer-driven projects."