GCM 110 Chapter Notes - Chapter 4: Delamination, Blistering, Flexography

• School: Ryerson University
• Department: Graphic Communications
• Course: GCM 110
• Professor: Diana Brown

Document Summary

Wood is the primary raw material for pulp, along with bagasse (sugar cane), bamboo, and hemp. 4 types of pulping processes: mechanical, chemical, semi-chemical, and thermo- mechanical: mechanical pulping. This process produces groundwood pulp (economical because all the wood is used) Contains impurities discoloration and weakening of paper. Uses: newsprints and magazines: chemical pulping. Removes most of the impurities such as lignin, resins, gum of the wood so pulp is mainly cellulose fibre. Done by cooking wood chips with chemicals. 2 types of chemical wood pulp: sulfite and sulfate. Sulfite pulp: cooking wood chips of coniferous woods in a liquor made from lime and sulfurous acid. Sulfate pulp (kraft): cooking wood chips of coniferous woods with caustic soda and sodium sulfide (stronger, used more than sulfite pulp: semi-chemical pulping (ctmp) Usually is blended with chemical pulp to ensure stiffness and good form: thermo-mechanical pulping (tmp) High yield of pulp from the wood.