Globally more than 4 m tons: Agricultural films are a challenge for recyclers

Agricultural films (Foto: Starlinger & Co. GmbH)

Vienna, Austria – 510,000 tons of films for agricultural use were sold in Europe in 2013, the majority of them in Spain (95,000 t), Italy (80,000 t) and France (55,000 t). Other major users are Germany, the UK and Poland. The market for agricultural film has been experiencing steady growth over the past decade. Studies valued the global market for agricultural films at 4 million tons in 2015 and expect a growth at a Compound Annual Growth Rate of 5.6 percent from 2015 to 2030. China emerged as the leading consumer of agricultural film worldwide and accounted for more than 61 percent of the total demand in 2012. Asia and Australasia are the regions with the fastest growing demand on agricultural films, followed by Europe, CIS and Russia, and the Americas.

The growing quantities of film used for agricultural purposes accounts for increasing amounts film waste. As many countries have implemented restrictions for landfilling, the need to recycle the film waste arises. The fact that collection schemes for agricultural films already exist or are being installed in many countries – e.g. in Germany since 2014 and in Spain and the UK by 2015 – makes collection easy and helps to increase the amount of post-consumer agricultural film that enters the closed-loop economy.

Hard to determine type and degree of contamination

The recycling of post-consumer agricultural film poses some challenges for recyclers. When the collected materials arrive for recycling, they are mostly a variety of polymers mixed together. Also, contamination is a big issue. As the waste film very often is pressed into bales for transportation, it is hard to determine the type and degree of contamination. Often, there is a lot of organic matter on the film which might already have started to decompose, and possible solid and/or abrasive contaminants must be removed by means of special melt filtration before pelletizing.

Humidity from outside storage and/or washing requires special pre-drying to allow trouble-free further processing. Depending on the moisture content, different drying methods such as venting or air flushing must be employed. Thermic drying is very energy intensive in this case due to the very thin material and the large surface. Also, a significant share of material is lost as fluff in the drying process in the cyclone. If the moisture content in the input material is less than 2 percent, it can be processed without venting. A moisture content of up to 4 percent requires venting, and if it reaches up to 6 percent, air flushing is required. Materials with a very high moisture content – up to 8 percent – can be processed on recycling lines equipped with air flushing combined with a reinforced agglomerator drive. A cascade agglomerator allows the processing of materials with an even higher moisture content – up to 15 percent is possible.

Flexibility is another important matter. Due to seasonally fluctuating availability of input material the recycling equipment must also allow the processing of other materials such as geotextiles, irrigation pipes, containers, and others in the meantime. In addition, the equipment should be wear resistant and have a high uptime.

Technical solutions for recycling

Depending on the quality of the regranulate, recycled agricultural film can be reused in film production or other applications such as extrusion and injection moulding (tubes and pipes, containers, etc.).

Starlinger recycling technology, a business unit of the Austrian mechanical engineering company Starlinger & Co. GmbH, supplies recycling equipment and has already installed a number of recycling lines for applications such as agricultural films. Starlinger’s recoSTAR dynamic recycling lines – the successor of the recoSTAR basic series and on the market since spring 2015 – are especially designed for the processing of highly contaminated and washed post-consumer film. Depending on the requirements of the application the lines can be equipped with various types of degassing units, for example the integrated but independent C-VAC module, discontinuous and continuous melt filters, and four different types of pelletizers.

Maximum degassing capacity

In order to obtain the high quality granulate required for applications such as injection moulding and film extrusion, the melt needs a high degree of purification. Depending on the type and amount of contaminants the melt contains, gas is formed that could cause foaming in the melt and consequently entrapped air in the granulate. Air bubbles in the regranulate generate problems in the subsequent production process, e.g. specks and holes in the produced film, etc.

The high-capacity degassing module C-VAC can be combined with any Starlinger recycling extruder. It increases the degassing surface of the melt and thus enhances degassing efficiency, removing effectively all the gases which have formed during the extrusion process due to the composition of the input material. With the C-VAC module, difficult-to-recycle scrap can be turned into high-quality regranulate that is apt for use in a wide range of applications and sells at higher prices. The line concept also allows up-cycling by adding additives – another option that widens the possible usage of the produced regranulate.

Source: Starlinger & Co. Gesellschaft m.b.H.