Stone paper, also known as limestone paper, rock paper, generically referred to as bio-plastic paper, mineral paper or rich mineral paper, is a type of strong and durable paper-like material manufactured from calcium carbonate bonded with small amount of resin high-density polyethylene. It is used for stationery, leaflets, posters, books, magazines, bags, packaging, wallpaper, adhesives, tags, in-mould labels, plates, trays, containers, and maps among other uses.
Production
Stone paper consists of 3 components : calcium carbonate, high-density polyethylene, and usually a proprietary coating developed by the individual supplier. High density polyethylene is a non-toxic resin. The proprietary coating serves to enhance printingquality and performance for applications in printing papers.
Properties
Stone paper has a density range of 1.0-1.6g/cm3, which is equal to, or slightly higher than, ordinary paper and a texture somewhat like that of the outer membrane of a boiled egg. It may be recycled with Number 2 plastics or remade into rich mineral paper again, and is not biodegradable but is photo-degradable under suitable conditions. Because it is not made from wood fibers, stone paper possesses a smoother surface than most traditional paper products, eliminating the need for a coating or lamination. The source of the calcium carbonate is waste material collected from marble quarries and offcuts which are ground and reduced to fine white calcium carbonate powder. The production of stone paper uses no water, acid, bleach or optical brighteners. It can be recycled endlessly, but only if recycled separately at civic amenity sites. Stone paper is compatible with inkjet or solid ink printers but does not respond well to very high temperature laser printers.
Sustainability
Comparisons have been made between stone paper and traditional paper for applications like book printing in Europe. If stone paper were to replace coated and uncoated graphic printing stock in Europe, it could potentially reduce the according CO2 generation by 62%, water consumption by 99.2%, and wood usage by 100%. These results depend however on the type of calcium carbonate used for stone paper and the source of the HDPE. The ratio of oil required to make virgin HDPE for stone paper is such that large scale replacement of traditional paper could save 46% of oil consumption from the current European graphic paper supply with virgin and recycled components.
