Cellulose nanocrystals coating – A novel paper coating for use in the graphic industry
The rising concern about the impact of printing material on the environment is pushing the graphic industry to turn towards the use of materials derived from abundant, renewable resources. The end-result of this process would be a replacement of conventional printing materials that are often derived from unsustainable resources. The aim of this study was the application of cellulose nanocrystals (CNC) coating as a novel type of sustainable coating that might eliminate use of synthetic coatings. The selected coating was prepared from cellulose nanocrystals suspension that was derived from cellulose fibrils on the laboratory scale. The coating formulation examined in this paper was not yet used on the industrial scale. Experimental research was carried out in the form of preliminary laboratory tests for offset printing application using IGT test methods of ink transfer and set-off. Paper coated with cellulose nanocrystals was used as a printing substrate, while vegetable oil-based ink was used as a printing ink in order to stay in line with environmentally preferred choice of printing materials. The results indicated an increase in surface gloss on paper coated with cellulose nanocrystals, as well as in print gloss on printed paper coated with cellulose nanocrystals. The downside of cellulose nanocrystals coating was the prolonged drying time of ink. Further research should be dedicated to improving cellulose nanocrystals coating as the formulation used in this study caused undesirable cockling and waviness on selected paper grade.