Manufacturing & Materials Finalist: RHOBARR™ Barrier Dispersions Platform - Tech Briefs

Brand owners and consumers continue to demand more sustainable options for single-use food packaging. Paper-based packaging offers an attractive solution because it is a renewable raw material that can be processed within existing recycling infrastructure. However, incumbent technologies for rendering paper impermeable to food-based substances like oil and grease, fatty acids, and hot/cold beverages can negatively impact its ability to fit into a circular economy. Traditionally, fluorocarbons are applied at low levels and low cost by treating the paper fibers in the pulp phase. This treatment strategy risks fluorocarbon release into the environment either as the paper biodegrades in landfills, or in the water discharge from the recycling process.

An alternate strategy is to apply a physical barrier such as a polymeric barrier coating, most commonly via extrusion coating in which solid polymer pellets are heated, extruded into a molten film, and applied to paper. However, the extrusion process requires thick films to achieve suitable mechanical adhesion to the paper substrate and to provide a continuous, defect-free film, which can lead to difficulties recycling the coated paper articles.

The innovative RHOBARR™ line of high-performance waterborne coating products for recyclable paper-based packaging offers award-winning technologies that provide barrier against oil and grease, fatty acids and mineral oil, and hot/ cold liquids, along with additional packaging properties such as heat seal, film flexibility, and block resistance. RHOBARR™ Barrier Dispersions are applied to paper/board as an aqueous dispersion, then dried to form ultra-thin (95 percent fiber recovery rate in internal testing (Voluntary Standard for Repulpability from the Fibre Box Association (FBA)), (iii) internal cradle-to-grave life cycle analyses validating significant improvements over extrusion-coated paper, and iv) external validation of ~30 percent bio-renewable carbon content (Beta Labs according to ASTM-D6866).

“High-integrity, defect-free film formation is a key mechanism by which RHOBARR™ Barrier Dispersions achieve barrier performance. A key challenge was achieving the balance between film integrity/flexibility and resistance to sticking during the winding/unwinding portion of the coating process (blocking),” said Allyson Marianelli, who is the Lead Researcher on this technology at Dow.

“For double-sided coating applications (e.g., sandwich wraps, bakery liners) where the dispersion is applied to both sides of the substrate, then dried and wound up on a reel, anti-block performance is critical. RHOBARR™ Barrier Dispersions provide flexible films that have excellent barrier and anti-block performance, ensuring the coated paper can be easily handled within existing coating and converting infrastructure,” she added.

Harnessing years of manufacturing, synthesis, and formulation expertise, Dow scientists have developed a product line comprised of the following offerings, with further products in the development pipeline including RHOBARR™ 320/325 Barrier Dispersion: hot/cold liquid barrier, heat seal; RHOBARR™ 214 Emulsion: mineral oil/fatty acid barrier, heat seal, low coefficient of friction; and RHOBARR™ 135 Emulsion: hot oil/grease resistance, microwave- and oven-use (ISEGA certified).

These RHOBARR™ Barrier Technologies are protected by a robust portfolio of intellectual property covering process technology, product composition, and application expertise. RHOBARR™ Emulsions are produced via emulsion polymerization or a proprietary mechanical dispersion process (BLUEWAVE™ Technology). RHOBARR™ Barrier Dispersions continue to gain industry share globally, with end uses in paper beverage cups, microwavable molded fiber bowls, and sandwich wraps.

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This article first appeared in the November, 2024 issue of Tech Briefs Magazine (Vol. 48 No. 11).

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