Recyclable And Compostable Coated Paper Stocks And Related Methods Of Manufacture

What is this patent about?

'039 is related to the field of coated paper stocks, specifically those designed for packaging applications requiring water, grease, and moisture resistance. Traditional solutions often rely on polyethylene films or wax coatings, which present challenges in recycling and composting due to their resistance to repulping and degradation.

The underlying idea behind '039 is to replace conventional polyethylene or wax coatings on paper with a two-layer system of water-based dispersions. This involves applying a primer coat to seal the paper substrate, followed by a top coat that provides the necessary barrier properties. The key is using specific water-based polymers and waxes that can disperse in water during repulping and readily biodegrade during composting.

The claims of '039 focus on a recyclable and compostable coated paper stock comprising a paper substrate coated with a primer coat and a top coat, both of which are water-based dispersions. The primer coat is selected from a group of polymers including acrylics, polyvinyl acetate, polyvinyl alcohol, ethylene-vinyl acetate, styrene-butadiene copolymers, or starch. The top coat is selected from acrylics, styrene-butadiene copolymers, or polyvinylidene chloride, and may further include a wax component.

In practice, the primer coat seals the porous paper surface, preventing excessive penetration of the top coat and ensuring a uniform barrier. The top coat then forms a film that provides water, grease, and moisture resistance. The selection of specific polymers and waxes allows the coated paper to be easily repulped in standard recycling processes, as the water-based coatings disperse, freeing the paper fibers for reuse. The resulting material also readily disintegrates during composting.

This approach differs significantly from prior solutions that rely on polyethylene or wax. These materials require specialized equipment for removal during recycling and do not readily degrade in composting environments. By using water-based dispersions, '039 offers a more environmentally friendly alternative that maintains the necessary barrier properties for packaging while simplifying recycling and promoting compostability. The specific combination of primer and top coat materials is crucial for achieving both effective sealing and barrier performance.