What are the factors that affect the whiteness of paper

Paper whiteness refers to the whiteness of the surface of the paper, that is, the ability of the paper to fully

reflect after being irradiated by light,expressed as a percentage. The quality standards of paper have clear

requirements for whiteness,so what are the factors that affect the whiteness of paper?

1.Whiteness of pulp

The whiteness of the pulp determines the basic whiteness of the paper. The whiteness of the pulp is high, and

the whiteness of the paper produced is also high.

2 The amount of filler added

The whiteness of general fillers (such as white earth, talc, calcium carbonate, titanium dioxide, etc.) is higher

than paper pulp, so adding fillers to the pulp can improve the whiteness of the paper. In paper production, due to

the different filler content on both sides of the paper, the whiteness of the two sides of the paper differs by 0.5

to 3.0 percentage points. When using white pigment for surface coating, the paper whiteness can be significantly

increased.

3.Effect of drying

Excessive drying of the paper, high temperature of the paper roll and long storage time will reduce the paper

whiteness.

4.Turbidity of white water for production

The whiteness of paper produced by clean water with low turbidity is higher than that of water produced by turbid

water.

5.Pulp lignin content

The high lignin content in the pulp or excessive bleaching will cause the pulp to age and turn yellow, reducing

the whiteness of the pulp.

In addition to the above factors,  must also be considered other factors that affect the whiteness of

paper, for example, the raw materials used for pulping, the design of the bleaching process, the design of

the deinking process etc.

 

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