FAQ (Frequently asked questions)
What are the differences between HDPE and LDPE?
PE-HD (HDPE) are loosely branched polymer chains that show a high density from 0.94 g/cm3 to 0.97g/cm3 (whereby HD stands for “high density”).
By contrast, PE-LD are highly branched polymer chains with a low density from 0.915 g/cm3 to 0.935 g/cm3 (whereby LD stands for “low density”). HDPE crackles when you hold it, whereas LDPE feels smooth and warm.
What is a flowpack film?
Flowpack film is processed on a horizontal or vertical flowpack machine. The film is wrapped around the product in the direction of processing and then heat sealed horizontally, then sealed at both ends with sealing pins and severed.
With the right machine, high quantities can be packaged per minute. Flat OPP films and polyolefin shrink films (in conjunction with a shrinking pipe) can be used.
What is MAP packaging?
Modified atmosphere packaging is the purposeful modification of the composition of gases in gas-tight packaging while the packaging is being sealed. Oxygen is one of the main contributors to food spoiling in unopened packaging when it is sealed in with the produce. The introduction of cover gases during the sealing process pushes most of the oxygen out of the packaging, significantly prolonging the shelf life of the produce within it.
Which gases are used depends on the barrier effect of the packaging and the sensitivity of the produce within. Nitrogen and carbon dioxide are the most frequently used gases and are usually used in combination with each other.
Do biodegradable films exist? How are they manufactured?
The disposal of plastics through composting has been intensively researched since 1990. The compostability of plastics has been defined since 1998 in DIN standard V 54900. To ensure biodegradability, the material has to provide structures for the enzymes and micro organisms to attach themselves to and so fuel their own metabolism. The enzymes convert the long polymer chains to water soluble pieces making them easier to handle. It is possible to use naturally occurring polymers (biopolymers) or synthetically manufactured chain units such as sugars, succinic or lactic acids. The presence of heteroatoms such as nitrogen or oxygen in the plastic are critical. The majority of the current 30 recognised, marketable, biodegradable plastics are polyesters, polyamides, polyester urethanes and polysaccharides. Unfortunately, the characteristics giving the polyesters and polyamides their impact and tensile strength (intramolecular hydrogen bonds in amides, aromatic components in polyesters) work against natural decomposition. Almost any improvement in biodegradability leads to a deterioration of the material properties. In 2013, the global production of biodegradable plastics was 1.6 million tons – compared to 299 million tons of standard plastics.
How can we save on resources in the production of packaging?
Generally speaking, the only way to save resources is by reducing the amount of material used (thickness, size, technology). The amount of petroleum can be reduced with the addition of sustainable resources or the use of more diverse natural resources (see: Do biodegradable films exist? How are they manufactured?).
There is a trend towards the use of packaging made from recycled materials. Nowadays, it is possible to produce films from 100% recycled materials. Every time a raw material undergoes heat treatment – a requirement for the manufacturing of films – mechanical properties such as puncture and rip resistance are reduced. The result is an increasingly thicker initial material, which at a certain point makes no ecological sense.
Which types of packaging are suitable for heating in the microwave and oven?
PP (polypropylene) is the material predominantly used for microwave safe packaging. PP is widely used and is available as a transparent or coloured (usually in black) version. It has a temperature resistance of -20 °C to +130 °C. CPET (crystalline polyethylene terephthalate or polyester) is the material predominantly used for ready meals for ovens. CPET is an opaque material due to its partial crystallisation, which ensures its form stability even at high temperatures. Almost all CPET products have an APET layer, producing excellent sealing properties and an attractive shiny appearance. The exact manipulation of the material’s crystallinity means that the product can be used at a temperatures ranging from -40 °C to +220 °C. This fulfils the consumer demand for impact force at low temperatures and form stability at high temperatures. In addition, CPET is a good barrier against oxygen, water, carbon dioxide and nitrogen.
How does the antifog coating work?
Antifog is a specific treatment for the surface of materials. The coating prevents vapour condensation on transparent materials. This is achieved by introducing special coatings or additives that prevent the development of microscopic drops that would otherwise scatter the light, rendering the material virtually or fully non-transparent. The antifog coating barely effects the visual properties of the treated film as this transparent layer is only a few micrometres thick.