The factors that affect the whiteness of paper are:
1) Whiteness of pulp
Pulp whiteness is the basic whiteness that determines the whiteness of the paper, the whiteness of the paste is high, and the whiteness of the paper produced is also high, and vice versa.
2) The amount of filler added
The whiteness of general fillers (such as clay, talc, calcium carbonate, titanium dioxide, etc.) is higher than that of ordinary pulp, so adding fillers to the pulp can improve the whiteness of the paper.
In production, due to the different content of filler on both sides of the paper, the whiteness of both sides of the paper varies by 0.5 to 3.0 percentage points. When white pigment is used for surface coating, the whiteness can be significantly improved.
3) Effects of sizing:
The application of rosin gum can reduce the whiteness of paper by 3 to 5 percentage points.
