Benefits of Surface Fluorination for Flexible Plastics

Apart from the benefits of excellent barrier properties with regard to the permeation of nonpolar liquids and good adhesion, little is known about the influence of surface fluorination on gas barrier properties. The permeability of only a few inorganic gases through surface-fluorinated plastics such as PE,19 PP, and PET20 have been evaluated to some extent. 

The influence of fluorine mixtures with or without reactive gases on the permeability of 02 and N2 through LLDPE was investigated.20 1 It was found, as 

Plastic film Film thickness Permeation Permeability 

Similar reductions in permeability were found for C02 and N2. Apparently this treatment method creates a universal gas barrier and is seemingly universal for polymers with a high hydrocarbon content. It is anticipated that by optimizing this approach, 02 permeability values for PE of less than 50 cm7m2 per 24 h will be achieved. 

The above results suggest a potential for utilizing surface fluorinated plastics for modified atmosphere and vacuum packaging applications. If needed, the barrier properties can be improved further by vacuum metalization. Excellent adhesion was found for vacuum-deposited aluminum on this new fluorinated layer, achieving an adhesion index of 10 using the classical cross-hatch method. With this treatment method it was also possible to heat-seal PP or PE onto PET. 

Petrol permeation through HOPE pipe at 50°C Pipe=Type 4 Class 10 petrol 93 octane high altitude. 

Polymer film Treatment time (min) Neutron activation O2 permeability N2 permeability  

Total surface fluorine concentration values (pg F/cm ) were determined using neutron activation analysis. 

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