In 2015, Hansol Paper Company, the largest paper mill in Korea, joined forces with US-based materials engineering company, Smart Planet Technologies, to develop a new mineralised coating. Chris Tilton, chief technical officer at the latter, sheds some light on the collaboration and lays out the benefits of mineralised resins over traditional plastic coatings.
Chris Tilton: We began early product development activities in the US in early 2015. The early development focused on identifying mineralised coating products servicing the high-barrier board market that is currently dominated by polyolefin extrusion coatings, such as polyethylene.
The objective was to identify a more environmentally friendly option with a similar performance as plastic coatings. Production trials begin in the US in 2015 and ramped up to full coating products in Korea. Final product testing, published specifications and market release took place in 2016. Hansol currently offers mineralised EarthCoating for folding boxboards and corrugated liners.
Mineralised coatings, compared with existing industry equipment, are inexpensive, waterproof, have an excellent moisture barrier and are greaseproof. The coating surface provides a very high-quality print surface compared with plastic coatings. Unlike polyethylene (PE), for example, the coatings break down into small, dense particles during repulping. These small fragments process differently to plastic flakes and do not have the same contaminating effects during recycling.
The coatings are designed to replace plastic coatings on paper boards, rendering the paper recyclable. Most often, the coatings comprise about 5-10% of the coated paperboard. The main benefit of EarthCoating is making the paper recyclable compared with plastic coated paper, which is not widely recyclable.
Because the mineral fillers such as carbonate are less expensive, they can reduce resin costs. Also, because the amount of plastic is greatly reduced, it protects the customer from large swings in the polyolefin resin market. For example, mineral fillers are approximately $0.08-0.12 a pound. Extrusion-grade polyolefin resins are normally at least $0.60 a pound and higher. Furthermore, EarthCoating resin provides similar performance when using the same coat weight, therefore, no additional weight is needed.
Smart Planet has successfully commercialised 40-51% of resins as paperboard coatings, including high-density polyethylene (HDPE), HPDE-PE mixes, polypropylene and PE, all of which are now on sale.
All of the coatings are waterproof, greaseproof and high-performance moisture barriers. The HDPE content coatings are designed to be a very effective barrier to oil, essential oils and fatty acids. Smart Planet is developing compostable and recyclable coatings using mineralised polybutyrate.
Mineralised coatings are an advanced drop in replacement for all 100%-polyolefin coatings. Example applications include wax replacement in corrugated liners and folding cartons. The coatings are an excellent heart-seal medium and function very well when used as a heat-seal closure.
Seventh Generation is a member of the How2recycle programme. Smart Planet contacted it as a fellow member. Once the environmental aspects of the technology were understood, it was clear Hansol ECO-B would support the programme of plastic reduction and also enhance the recyclability of its packaging.
Since Seventh Generation was using recycled boards, Hansol ECO-B was the perfect solution. It is 100% recycled, with 60% post-consumer content. Since the mineralised coating was found to be cost-neutral and to provide excellent performance, the Hansol ECO-B board-mineralised coating combination was perfect for the packaging programme.
Smart Planet has fully commercialised a wide range of products including deli trays, hot cups, microwaveable packaging and frozen seafood.