Processing Method
Lignocellulosic material produced by dissolving the lignin glue that binds wood fibres together. Chemical pulp relies on heat and chemical reagents to separate cellulose from other wood components. This method yields fibres that remain long and intact.
It differs from mechanical methods which tear fibres apart and leave lignin in the mix.
Structural Identity
Retention of high individual fibre strength allows for the production of strong paper and board grades. Because chemical pulp has low lignin content, the resulting substrate resists yellowing over time and provides a stable surface for high quality printing. Bleached variants provide the high brightness required for luxury packaging.
These fibres create a flexible network that withstands folding without cracking.
Extraction Chemistry
Cooking wood chips in a pressure vessel known as a digester constitutes the primary step in production. Most modern mills use the kraft process, where sodium hydroxide and sodium sulfide break down the wood structure. Acidic sulfite processes represent an alternative but are less common for packaging grades.
The yield of chemical pulp is lower than mechanical pulp because half the wood mass enters the liquid waste stream for energy recovery. Spent chemicals are recycled through a recovery boiler to maintain the economic viability of the mill. This closed loop system recovers energy and reagents simultaneously.
