Factors Affecting Coated Paper

The quality of coated paper depends not only on the base paper but also significantly on the composition of the coating. When various organic pigments are added to the coating to replace the commonly used white pigment-clay (kaolin)-properties such as whiteness, unprinted paper gloss, print gloss, opacity, and smoothness are directly proportional to the dosage of organic pigments; this indicates that organic pigments can enhance the properties of the coated paper.
When organic pigments replace titanium dioxide-a material characterized by high cost, high whiteness, and a high refractive index-the resulting coated paper shows properties (unprinted paper gloss, print gloss, and smoothness) that are directly proportional to the pigment dosage, whereas whiteness and opacity are inversely proportional. This suggests that for certain specialized applications, while organic pigments cannot entirely replace titanium dioxide, they can still maintain the paper's properties at a comparable level.
When organic pigments replace calcium carbonate-an inexpensive and widely used white pigment-properties such as whiteness, unprinted paper gloss, print gloss, opacity, and smoothness are directly proportional to the pigment dosage; this indicates that the use of organic pigments is an inevitable trend for further improving coated paper quality.
Regarding the relationship between coating weight and paper quality, paper coated with formulations containing organic pigments exhibits superior properties compared to paper coated without them; furthermore, when achieving similar paper properties, the use of organic pigments allows for a reduction in the coating weight. When using solid-type organic pigments, coating weight can be reduced by approximately 30%; with adhesive-type organic pigments, the reduction can reach about 40%; and with hollow-type organic pigments, it can even drop by around 45%. This demonstrates that organic pigments play a significant role in the trend toward paper lightweighting.
The quality of printed matter depends heavily on the substrate, which in turn is inextricably linked to the base paper, coating formulation, and surface treatment; therefore, selecting a high-quality paper substrate is the key to both reducing costs and enhancing print quality.