CYPET: Plastic drums made from pet, as a replacement for metal, HDPE or fiber drums

PLASTIC MATERIALS FOR DRUMS

The tendency of metal drums to rust and the sensitivity of fiber drums to wet conditions, have resulted in the popularity of plastic drums made from HDPE (high molecular weight high density polyethylene). Such drums are manufactured using extrusion blow moulding, a well-established process for the production of HDPE hollow containers. HDPE exhibits the right melt properties for this process and also combines rigidity with impact strength for mechanically sound containers. Other plastic raw materials are either not suitable for processing into hollow containers or do not exhibit the required mechanical properties for strong drums.

The only other plastic raw material that exhibits high mechanical strength and is suitable for processing into hollow containers is PET. In fact, PET is the only plastic strong enough to withstand the carbonation pressure of carbonated soft drinks and is the only plastic used for this application. In addition to its very good mechanical properties, PET also offers transparency and a smooth, glossy surface finish, making it easy to clean. It is also easily recyclable and can be upgraded during the recycling process to bring its properties back to their original levels, including the suitability for food contact applications after recycling.

PET cannot be processed with extrusion blow moulding, however a PET container can be produced with injection stretch blow moulding, by first producing a PET preform with injection moulding and then stretch-blow moulding that preform into a PET container as illustrated below. With this process PET bottles and jars have been produced over the past 40 years.

PET containers have very successfully replaced other materials such as metal, other plastics, glass and paper in many applications such as soft drinks, water, milk, juice, household cleaning products, chemicals, edible oils, peanut butter, pharmaceuticals etc., typically in sizes up to 2 litres. More recently PET has also successfully penetrated applications in the 5 - 30 litres size range, like 5 and 10 litre bottles for water and edible oil, 20 litre bottles for water dispensers, 15 – 20 litre stackable PET jerry cans for edible oil and chemicals as well as 20 – 30 litre kegs for draft beer.

PET PROCESSING TECHNOLOGY FOR DRUMS

Machines for PET processing have been commercially available for the production of PET containers up to a maximum size of 30 litres and for such large sizes, there is a restriction on the maximum size of neck diameter (mouth opening). As a result of the non-availability of machines capable of processing PET for drums, this market segment has not been developed for PET, despite the fact that PET drums offer a cost efficient and attractive alternative to HDPE Drums.

Since early 2014 when CYPET Technologies Ltd commercialized its patented single-stage PET processing technology, it is possible to produce PET containers larger than 30 litres, including open-mouth PET drums of up to 150 litres capacity and 400 mm mouth diameter. The CYPET innovative production system, injection moulds the preforms and also stretch-blow moulds them into containers on the same machine, in a way that enables large container production with minimal energy consumption.

The world’s first 50 litre PET container is a beer keg, which is in commercial production in Australia on a CYPET K 53 machine model. The world’s second 50 litre PET container is a milk drum with innovative built-in handles, which is in commercial production in Kenya on CYPET K 38 machine model.