Billboards fall into two categories: larger highway billboards (called bulletins) and smaller urban signage (called posters).The outdoor advertising industry maintains roughly 450,000 outdoor billboard locations throughout the United States. Given the short service span of advertising media - billboard companies are under considerable pressure to reduce the amount of waste they produce, either through prevention or by developing strategies that allow for a valuable reuse of the post display billboard waste. About 25 million sq.meters or about 10,000 tons of billboard fabric waste is generated annually in the US alone.
PVC coated fabric (Vinyl) billboards – the material of choice for billboards is a 3-layer composite material where the polyester scrim reinforcement is coated with flexible PVC on either side to yield the desired fabric. Both PVC and Polyester reinforcement in their virgin form are 100% recyclable via melting and converting into pellets. However, the integration of PVC coating onto the polyester scrim fabric makes separation of either component uneconomical such that complete recycling is not feasible. The industry is constantly seeking alternative use/reuse with an overall lower environmental impact. Innovative solutions have been devised for down cycling in to secondary applications that may benefit from some residual property of the material being disposed. This is necessary to avoid land-filling of toxic PVC and phthalate plasticizers that may leach out and pose a variety of long term health risks.
Polyethylene based (PE) materials, as a pure hydrocarbon, avoid the environmental stigma of the toxic PVC waste and the health risks of leaching phthalate plasticizers. However, PE based flex fabric is similar in construction to its PVC counterpart in that a HDPE base scrim is coated with LDPE on either side to make a 3-layer composite fabric. Additional aqueous coatings may be applied to facilitate ink adhesion. In recycling parlance HDPE and LDPE are separate and distinct waste streams and while they belong to the same polyethylene family they are indeed different in density, hardness, strength and their melt flow characteristics which influences reprocessing in a melt based 100% recycling operation. While both HDPE and LDPE in their virgin form are 100% recyclable, this opportunity may be severely devalued or curtailed for the case of a well integrated, coated and printed, composite plastic fabric.
