عنوان مقاله [English]
Background and objective: Utilizing coated papers depends on the selection and proper usage of the paper ultimate coverage structure. Since pigment forms 80 to 95 percent of the weight of the cover, it is clear that the type and characteristics of the ingredients, play an important role in the cover structure, light characteristics and the quality of printing. Zeolite is one of the substances that have recently entered the field of research in connection with coating. The aim of this study was to investigate the effects of 4A synthetic zeolite as pigment, on the physical characteristics of the coated papers with synthetic zeolite pigments in pure form and in combination with precipitated calcium carbonate and kaolinite.
Material and Methods: Requirements for this study 75 grams printing paper produced by mill Kayvta Finland, 14 and 30 grams of coating weight were considered on one side of the paper, and different calendaring conditions (70 and 90 centigrade temperature) were also considered for the samples. Some of the physical characteristics of the coated papers were considered like thickness, surface roughness, gloss, gloss variation, opacity, brightness, light scattering coefficient, whiteness and yellowness.
Results: One of the very important factors, for the consumers of coated papers is the low level of yellowish. Using zeolite makes this factor to decrease dramatically and also coated papers with zeolite benefit a high whiteness as the white papers coated with calcium carbonate. Brightness of the paper coated with zeolite is higher than the papers coated with calcium carbonate and calendaring caused a little reduction of the brightness. Before calendaring, papers coated with calcium carbonate has the highest scattering coefficient and also after calendaring, has the highest amount of light scattering coefficient despite large reduction in the amount of light scattering coefficient. And as a result of this, they have a high opacity. The results also showed that adding a small amount of calcium carbonate and kaolinite to zeolites improves light scattering coefficient and opacity of the papers. The results showed that paper coated with zeolite has a small amount of gloss. Calendaring increase the gloss of all the treatments and this increase is more evident in calcium carbonate and kaolinite. Adding calcium carbonate and kaolinite to zeolites improves the gloss of the papers coated with them and it seems that because of hardness of zeolites comparing to other pigments it is better to apply more pressure for calendaring than the pressure that was used in this research.
Conclusion: In summery it can be said that 4A zeolite can be a good alternative for precipitated calcium carbonate and kaolinite, because of its unique physical characteristics. And the most ideal condition for using synthetized zeolite and reducing the amount of its deficits is to combine it with calcium carbonate and kaolinite.
Keyword: Coating, Physical properties of paper, synthesis zeolite, precipitated calcium carbonate, kaolinite