Marden Edwards Journal

It is now nearly a year since I wrote the Overwrapping films come full circle and nearly six months since the “Packaging and the Environment – the Role of Film Overwrapping” articles. The purpose of this article is to bring some of this information up to date and to outline some of the developments within biodegradable films and specifically their application to overwrapping.

There are now three competing technologies for biodegradable overwrapping films. These are films made from polypropylene, films made from polylactic acid (corn starch) and finally films made from cellophane (wood pulp).

Oxo-biodegradable BOPP films (from oil) - such as

This is a technology that I had not come across until very recently. It is the same process by which plastic carrier bags can become compostable. An additive is added to the oil based film resin so that after a pre-determined time, depending on the amount of agent used, the film starts to bio-degrade. From a cost perspective this is a very attractive proposition since the film is essentially the same as traditional BOPP.

However, this type of film needs both oxygen (hence oxo) and light to biodegrade. I am led to believe that at the bottom of a landfill waste site the necessary oxygen or light will not be supplied and hence no composting will occur. In addition, this film is not CO2 neutral in that since it is oil based no CO2 has been absorbed in its manufacture. On the other hand, BOPP is a by-product of oil used to produce fuel and could otherwise by flared off or disposed of in some other way.

Much more information regarding oxo-biodegradable films can be found from the Oxo-Biodegradable Plastics Association in their excellent briefing document.

Polylactic acid films (from corn starch) such as Biophan from Treophan

This type of film is derived from corn. The problem which arises with both crops grown for fuel (bio-fuels) as well as crops grown for plastic is that this extra demand for agricultural land has led to dramatic increases in food prices.

In his article, Bioplastics: Time to Act, Dr Harald Kaeb, Chairman of the Board of European Bioplastics, argues that rather than simply using crops to produce fuel, they are much better suited to producing plastics. The plastic products can then be re-cycled into energy by incineration once they are no longer required. For this to happen, however, better re-cycling facilities need to be in place which can separate materials for composting and materials for combustion.

Bioplastics are beginning to look an attractive, green option as long as the acreage used for their cultivation is in addition to what is required for food purposes. Although they are compostable in the right circumstances, bioplastics are in fact well suited to be used for energy recovery by incineration.

Cellophane films (from wood pulp) such as Natureflex from Innovia

Cellophane is a filml that is used for wrapping which has been in production for over eighty years. Natureflex is a type of cellophane which does not require a plastic coating to make it heat seal. Made from wood pulp, Natureflex already uses material from a sustainable source where the land used is unsuitable for growing food crops. In addition, Natureflex will completely biodegrade in the absence of heat or light.

Summary

The one vital piece of information which needs to be used to calculate the environmental friendliness of each film type is missing. This information is the amount of energy required to produce the film in the first place. It is my estimate that oxo-biodegradable BOPP uses the least, followed by polylactic acid films and finally cellophane. However, only PLA and Cellophane films absorb CO2 as part of the lifecycle process.

The absence of a method of sorting compostable and combustible films also means that if the majority of film goes to landfill, currently only cellophane will fully bio-degrade. Once a sorting system in place, either for incineration or high temperature composting, the oxo-biodegradable and PLA films might take the crown for greenest film.

A good case can be put for using any of the above film types. Which one is selected depends upon the customer’s own set of environmental concerns and issues. As far as Marden Edwards overwrapping machinery is concerned, the choice is equal since all types of film can happily run on Marden Edwards packaging and wrapping equipment. As ever, a combination of price and market requirement will determine which bio-degradable films are selected for which application.