200 μm Thick Polypropylene as a Temperature Stable Steel Laminate for Aerosol Valve Mounting Cups

Polymer lamination is a common coating method for packaging applications utilising steel substrates. The durability of the PP laminate at low temperatures makes it a potential candidate in aerosol cans as a replacement for O-rings commonly used in the valve assembly, while its high temperature stability makes it ideal for the processing conditions typically used in the lamination of packaging steel. The use of 200 μm thick polypropylene (PP) as a lamination material for protection of tinplate and electrolytic chromium coated steel (ECCS), with a view to their use in aerosol valve mounting cups, is explored. Here we show that the 200 μm thick PP retains its dimensional stability and adhesion properties during lamination at 165-190°C and sterilisation at 121°C for 90 minutes and shows excellent corrosion barrier protection with no polymer cracking after sterilisation and subsequent wedge bend tests. Further investigations into potential hairing of the laminate may be required, but the initial results suggest that a 200 μm thick laminate of PP on tinplate or ECCS would be a good candidate for use in a valve mounting cup for aerosol applications.