Improvement of barrier properties for packaging applications

In general, the possibility of adding a ‘natural’ label to modern packaging materials is attractive, as there is a growing demand for 'greener' products. In the recent years, considerable attention has been focused on developing hydrophobic cellulose fibres due to their wide variety of functional applications (hydrophobic papers, bandages, etc.). Natural polymers can be used as fillers in order to enhance bonding capacities with pulp fibres and to improve many properties, important for packaging paper (oxygen, grease, antimicrobial properties etc.). The aim of our research was to improve the barrier properties (moisture, water and grease resistance) and also smoothness of paper sheets, by using two different bio polymers as wet-end and surface application (alkyl ketene dimer and corn starch) and to evaluate the applicability of the methods for packaging paper for household and food application. Surface hydrophobicity depends mainly on the consumption of the additives used and for secondary fibre material (Group 1.05.00) blends of 1% of o.d.f. of alkyl ketene dimer and corn starch is sufficient. One-sided sized coated papers with resistance to grease in the range of values Kit 3 to Kit 4 were prepared with an alkyl ketene dimer and corn starch from secondary paper. Alkyl ketene dimer with coating weight of 7 g/m2 is more applicable for grease resistant paper, rather than starch with the same weight. The surface properties were investigated by atomic force microscopy analysis finding out that better results are obtained which coatings consisting alkyl ketene dimer with coating weight of 7 g/m2.