Plastic[Plastic?:Plastic sample cutting machine] material is the fastest growing packaging[packaging?:DCP-H series packaging sample cutter plotter] material which represents 50% of all goods packaging due to its wide variety of possibilities and properties.
For it is possible to tailor its properties to suit different purposes, it has low weight and is relatively cheap and easy to produce and shape. Technical disadvantages of plastic are that it can react with the packaged product and does not provide an absolute barrier against gas and vapour (as glass does for example).
Plastic packaging mainly consists of polymers, which are long chains made up of small, individual links: monomers. The type of monomer and the molecular structure (whether the polymer chain is linear, branched, cross-linked, whether it is made up of one type of monomer or several types of monomer and how the lateral groups or banches are arranged) decide many of the polymer's properties.
Pure polymers are not suitable as packaging materials. Additives (such as antioxidants, UV stabilisers, pigments, anti-fog agents etc.) are used to make the production of polymers easier or to change or improve properties.
It is the product's requirements for protection and the desired quality and/or shelf life that decide the choice of material. Parameters that must be considered include appropriate safety, migration, neutrality of taste and smell, barrier qualities against oxygen, CO2, water vapour, aroma and light, temperature during filling, storage, distribution, machine suitability (serviceability and sealing properties), reuse/recycling and price.
In some cases where there is no very stringent requirement for barrier properties, such as an O2 barrier, a single polymer (single layer material) may be sufficient. These may be materials like polyethylene (PE), polypropylene[polypropylene?:flatbed digital polypropylene/pp cutting machine] (PP) or polystyrene[polystyrene?:cnc ps/polystyrene cutting machine] (PS). (In general we can say that materials with an oxygen transmission rate [OTR] of 10-100 [ml O2/m2 24 hr, 1 atm] are considered to be good barriers, OTR 1-10 as very good barriers and <1 as extremely good barriers). Which you choose will be decided by the requirements for barrier properties, ductility, processing method and price.
Polymers with different properties are often combined so as to obtain a material that is a barrier against humidity and O2 and may be easily sealed together and shaped.
The different polymers may be laminated together using glue or they may be coextruded and joined with a so-called tie layer (which is a type of polymer and not defined as glue).
