Application of TiO2 to Improve the Brightness Stability of HYP Containing Coated Paper

Eco-friendly high-yield pulps (HYP) are becoming increasingly used to product high value-added fine paper that is traditionally produced exclusively with chemical pulps. However, due to the presence of a large quantity of photosensitive lignin in the HYP pulp to more effectively utilize woods resources, there is a concern on the long term brightness stability of HYP containing paper. In this research, various TiO2was added to coating colors to improve the light fastness properties of HYP containing coated paper. The effect on the stability of optical properties of coated paper including brightness, opacity, color difference and the degree of brightness reversion before and after accelerated aging were studied. It was shown that the brightness stability of the HYP containing coated paper increased with increased addition of TiO2. Rutile TiO2was especially more effective than other types of TiO2on yellowing inhibition of coated paper. At a dosage of 3 parts of rutile TiO2, the brightness stability of coated paper containing 20% of HYP was found to be even better than paper made of 100% chemical pulp coated with conventional coating color.