(394b) Surfce and Aging Characteristics of PAPER Coated with NANO SIZE ZINC OXIDE Pigment

Quality of paper is improved on pigment coating in terms of surface, optical properties and printability characteristics. One of the major parameter for aqueous pigment coating is the type of pigment used and also its particle size and distribution. Zinc oxide is one of the pigments employed for special coating application. It is off let nano size particles are playing prominent roles in several areas ranging from medicine to electronics. In paper making there is no exception. Few speciality grades of paper are already using nano size calcium carbonates both as filler and also as coating pigments. Application of water based barrier coating in paper and board in food packaging industry have proven successful. It is also important due to substantial smaller size particles (nano range) compared to macro size solid particles (in micron range) can provide better   functional properties of paper in some specialized applications. However, ZnO is present in various forms nano size ZnO particles can enhance the properties significantly to improve optical and surface properties and specially the effect of aging. In this present investigation, therefore an attempt has been made to study the potential technological applications of nano zinc oxide particles on paper surface made from hardwood furnish and bamboo using 100% nano  ZnO and with admixture of coating grade China clay using laboratory rod coater. All the required properties were evaluated as per ISO standard and compared with the same base paper coated with micro size ZnO pigment particles. From the detailed study it is observed that paper coated with nano ZnO particles imparts better properties as compared to bulk ZnO. The results indicated that paper coated with nano ZnO imparts better properties as compared to bulk ZnO in terms of brightnesss, whiteness, gloss, smoothness and printability. Aging properties were also thoroughly studied under artificial conditions of varying temperature (10°C – 45°C) and humidity (40% to 95%) and fixed intensity of UV light. Paper coated with nano ZnO showed better resistance to brightness reversion and predicted better UV protecting potential.