Process for preparation of oxygen barrier film

A process for the preparation of an oxygen barrier film having an oxygen barrier layer and a treated substrate, the process comprising the steps of:

• a) subjecting a polyolefin substrate to a surface treatment to obtain a treated substrate wherein the surface under the parts of the curves corresponding to the C—O, C—N and C═O groups is at least 10% based on the total surface under the curve as obtained by X-ray photoelectron spectroscopy (XPS),
• b) applying an aqueous or hydroalcoholic coating composition comprising 0.1 to 25 wt % of polyvinyl alcohol, 0.1 to 30 wt % of a metal alkoxide and optional silicate minerals on the treated substrate obtained by step a) and
• c) drying the coating composition to obtain the oxygen barrier layer resulting in the oxygen barrier film,
• wherein the amount of the optional silicate minerals in the coating composition is less than 10 parts by weight per 100 parts by weight of the polyvinyl alcohol in the coating composition,
• wherein
• the polyolefin substrate is a polypropylene substrate and the oxygen barrier film has an oxygen transmission rate of at most 50 cc/(m2·24h), at a relative humidity of 0% and a pressure of 1.013×105 Pa, or
• the polyolefin substrate is a polyethylene substrate and the oxygen barrier film has an oxygen transmission rate of at most 100 cc/(m2·24h), at a relative humidity of 0% and a pressure of 1.013×105 Pa.