Process for optimising a gas barrier coating

A process of enhancing the gas barrier properties of a composite laminate material whilst providing an adequate bond strength between two flexible plastics films, in which a gas barrier coating comprising a clay and a polymer is positioned between the two flexible plastics films, wherein:

• a. a first flexible polymer film is coated with an aqueous dispersion of a clay, and a PVA and/or EVOH;
• b. an adhesive coating is applied to either or both of the coated side of the first film or to a second flexible polymer film;
• and
• c. the first and second films are adhered together, to provide a laminate material in which:
• (A/B)·(C/D)≧1500;
• and in which:
• A/B>75;
• C>1.0;
• and
• D<1.5,
• wherein:
• A is the Oxygen Transmission Rate for the laminate at 23° C. and 50% RH without the coating;
• B is Oxygen Transmission Rate for the laminate at 23° C. and 50% RH with the coating;
• C is the Bond Strength in N/15 mm between the first and second flexible plastics films after the adhesive has fully cured;
• and
• D is the Coating Weight in g/m2 (dry) of the gas barrier coating;
• wherein the PVA and/or EVOH is an aqueous solution or dispersion;
• and
• wherein the aqueous dispersion of the clay and the aqueous solution or dispersion of the PVA and/or EVOH are mixed prior to step a.