22 августа, 2015 
Malyar Vinyl coatings based on polyvinyl chloride (PVC) or modified PVC’s are also used as coatings for some internals. There are three main classes of PVC based resins:
a) vinyl solutions (vinyls)
b) organosols
c) plastisols
Vinyls are low solid coatings because reasonably high molecular weight resins are necessary to achieve the required mechanical and resistance properties. Being essentially thermoplastic, there is no crosslinking to increase the molecular weight. The higher the molecular weight of a resin, the higher its solution viscosity.
Organasols and plastisols are dispersions of PVC. Plastisols contain only PVC and plasticiser being about 90% solid. They are used in compounds for gaskets on closures or sealing seams. Organosols consist of 40-80% PVC, plasticiser and organic ‘solvent’. The PVC is not dissolved, but swells in the solvent.
Whilst not designed for crosslinking, modified PVC resins may undergo a small degree of crosslinking. Some aminoplast crosslinker is normally present. Most PVC containing materials are restricted to internal usage. For some difficult external applications, a PVC size coat may possibly be used. There has been much adverse publicity towards PVC, and its usage is declining in can coating applications. Nonetheless, PVC combines high degrees of flexibility with a high level of protection, a compromise of properties difficult to match with other resin systems. PVC based systems are used for internal coatings for easy-open ends for DWI beer and beverage cans and full aperture easy-open ends for food cans. DRD food cans may have a PVC based internal lacquer. PVC based coatings will not be considered further in any great detail.
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