Marden Edwards Journal

With a greater emphasis on environmental sustainability, bio-degradability and cost reduction there is a greater focus being placed on wrapping products with paper.  Whether it is being used for gift or presentation purposes, protection or for distribution and transit purposes, paper as a wrapping material can offer a quality impression that also conforms to the most stringent of environmentally conscious concerns.

All Marden Edwards base seal overwrapping machines can already wrap with paper instead of film.  The positive gripper system that transports the wrapping material through the machine is perfect for reels of paper resulting in no machine conversion work necessary.  However, for this simple conversion to happen it makes the assumption that the paper itself can be already be sealed by heat.

There are two types of self adhesive paper available, paper which contains a thin plastic coating which seals when heat is applied and paper where the a glue is pre-sprayed in the exact places where the seal needs to be made.

The plastic coated paper can be expensive and has the problem of not being able to fully bio-degrade.  The advantage is that it can be run on any existing Marden Edwards overwrapper with no conversion.  Paper where the glue has been sprayed into discrete locations is less expensive but the overwrapping machine requires the fitting of a standard print registration system to ensure that the paper and seals are accurately placed around the pack being wrapped.  The biodegradability of the glue can also be in question but recent developments by such companies as Parkside Flexibles have resulted in materials which have complete bio-degradability.

If non adhesive paper is to be used, Marden Edwards can supply one of its range of KAP Kraft paper overwrappers, which applies the glue to the paper as the machine is running.  Marden Edwards has manufactured over two hundred of this style of machine and the PVA, sugar based dextrin or hot melt glue is applied inside the machine as the materials are running through.  Typically PVA and dextrin are used for presentation quality wrapping whereas hot melt glue is used when the paper is replacing cardboard for reducing casepacking costs.    

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.

The short answer is an un-reserved “Yes”!. However, it is worth examining what constitutes an environmentally friendly wrapping film.

For many years the standard for over wrapping film has been BOPP, or Biaxially Orientated PolyPropylene. BOPP is manufactured from an oil based polymer and so is not biodegradable. Where waste is incinerated, BOPP film contained within the waste does act as a fuel and so improves combustion. BOPP does provide excellent clarity, barrier and strength properties at an economic price. The Exxon OPP website provides more information regarding the properties and applications for BOPP films.

However, as already explained in a previous Marden Edwards Journal article, “Overwrapping films come full circle”, cellophane used to be the material of choice for wrapping from 1912 (when cellophane was invented) onwards. Cellophane was made from cellulose, which is wood pulp, and this is inherently biodegradable. With the advent of a greater environmental consciousness, there is now a renewed interest in “green” and “environmentally friendly” wrapping materials and machines.

“Tuck and Fold” over wrapping has always been an environmentally friendly method of wrapping when compared to Polyolefin shrinkwrap. For shrinkwrap to produce a tight finish, the film requires a high shrink property when heat is applied. This results in high energy shrink tunnels being required for all over heating compared to overwrap’s requirement for localised concentrated heat to produce the lateral and end seals.

All Marden Edwards overwrappers are able to run with heat sealable paper with the paper being pre-trated with glue in the areas of the seals during the converting process. In addition, the KAP range of overwrappers can apply glue to uncoated paper during the wrapping process producing the equivalent of a paper casepack. However, wrapping with paper does not provide visibility of the product and for this only film will do.

Today, there are two main competing biodegradable types of film suitable for overwrapping – those that are manufactured from cellulose, such as Natureflex manufactured by Innovia and those made from PLA (polylactic acid) such as the Biophan film manufacture by Treofan. Whereas Natureflex is wood pulp based, Biophan is based on corn starch processed into a polymer by Natureworks.

Although predominantly designed as a replacement for Polyethylene (PE) Ecofilm from Cortec can run on Marden Edwards overwrappers producing a wrap suitable for transit and distribution multipacks.

The bio-degradable abilities of these products can be seen by this photograph of a biodegradable plastic cup. It is important to note that for composting to occur a high temperature needs to be maintained over a period of time.

In terms of true ec0-friendliness the debate has intensified further. The Friends of the Earth organisation has questioned whether producing fuel, and by implication bio polymer, from crops does in fact increase carbon released into the atmosphere by promoting the destruction of wetlands and forests. It argues that better management is required to monitor the complete lifecycle effect. The feedstock required for cellophane, on the other hand, comes from wood pulp which can be derived from existing, sustainable forestry.

With regards to Marden Edwards machinery, the positive gripper film draw mechanism has always been extremely tolerant to many different types of film and paper. It has the ability to handle very thin (17 micron or less), very thick (greater than 60 micron), very stiff (such as PVC) and very floppy (such as Polyethylene) films. In addition, the other strength has been the ability to run poorly wound and poorly stored films.

Because of Marden Edwards’ near 50 years of over wrapping expertise, BOPP, cellophane based and the new corn starch based films run equally well across the entire Marden Edwards range. It is noticeable that for some industries, such as Tea production, the shift to bio-degradable films is accelerating. Both new and old Marden Edwards machines are today running these films with no special adaptation.

Over wrapping machines have long been referred to as cellophane wrappers, cello wrappers or simply box wrappers. The overwrap itself has been known as a cello wrap. This terminology has its roots in the 1950s when all wrapping was with the wood pulp derived product call cellophane. Cello derives from the word cellulose, which is the primary structural component of green plants. It was first used for confectionery wrapping in 1912. Cellophane is coated with a thin plastic coating to ensure it seals when used for wrapping. Being wood based the manufacturing process is expensive but importantly cellophane will biodegrade. Cellophane was the most common form of plastic film made until 1963, when it was overtaken by polyethylene.

OPP (Oriented PolyPropylene) film is derived from melting and orienting or stretching the polypropylene polymer. The raw material is an oil by-product and its simple formulation which contains no health or environmentally hazardous materials . The resultant film has excellent strength, barrier and stiffness properties making it extremely suitable for over wrapping machinery. With the introduction of some small amount of shrink property (typically 5%) polypropylene can form a skin tight finish around a product without the need for large energy requirements. OPP will not bio-degrade but will assist combustion of waste when used in an incinerator breaking down into hydrogen and carbon.

Another wrapping material which was introduced in the 1950s, PVC (Poly Vinyl Chloride) has reduced in significance. PVC has an excellent shrink property when used with overwrapping machines but concerns regarding unhealthy dioxins produced both in its manufacture and incineration have reduced its widespread use.

Although not widely regarded as a material for use with overwrapping machinery, PE (polyethylene) runs extremely well on Marden Edwards machinery. LDPE (low density polyethylene) is extremely strong and ductile but does not have the clarity of other film types. This makes it suitable for use in transit wrapping applications, predominantly using shrink wrapping machines. However, because of the positive way that Marden Edwards overwrapping machines guide and transport the film it can be used for overwrap. It is not biodegradable.

Film producers, to keep up with the current requirement for re-cycling and enironmentally friendly products, have returned to the cellophane tradition begun near the start of the twentieth century. For example, Treofan’s Biophan wrapping film is manufactured from PLA (polylactic acid), a polymer derived from starch. Starch is itself derived from corn, sugar cane, straw or wood which are all renewable primary products. The qualities of the film itself are similar to cellophane and will decompose rapidly in composting bins if kept at the correct composting temperature. Innovia’s new Natureflex wrapping film is also biodegradable and is itself based on cellophane. Both of these films are very suitable for use with overwrapping packaging machines and show exactly how film overwrap has come full circle.

Leading UK based overwrapping machinery manufacturer Marden Edwards has recently supplied one of its popular B100FF machines to a French producer of herbal infusions to produce a high quality wrap on its cartons using a biodegradable film.

The B100FF is an extremely flexible machine used throughout the tea and coffee industries as well as in other applications where shelf appeal is paramount. It can handle a wide range of carton sizes and produce an envelope or end-fold wrap using all types of heat sealable films.

The customer in France runs a small, artisan style operation which has been using locally grown herbs to produce a range of boxed tea bags since the 1980s. The company maintains a responsible environmental policy and in keeping with this, looked at ways of making its packaging as environmentally friendly as possible, without detracting from the appearance.

This led to the choice of Biophan biodegradable film for overwrapping the cartons. Produced by Treofan, Biophan has similar aesthetic and handling characteristics to cellophane, however it is produced from corn starch and can be disposed of in an environmentally friendly way along with paper. In an industrial composting plant, Biophan will break down completely to carbon dioxide and water within 45 days.

The positive film handling system used on Marden Edwards overwrappers is ideal for use with this new generation of wrapping films and the method of wrapping produces an attractive, high gas barrier overwrap. It is also more environmentally friendly than other methods of wrapping as there is no requirement to shrink the film around the pack, providing a considerable saving in energy usage.