Performance Characteristics of Paper and Boards

Objectives

• Understand the common sources and manufacturing processes of papers and boards.
• Familiarize with common stock forms of papers and boards.
• Identify specific qualities for a selection of papers and boards.

Sources and Composition of Paper

• Composition: Paper and board are primarily made from cellulose fibers derived from plants.
• Examples of fibers:
  • Waste sugarcane (bagasse) is commonly processed into paper products.
  • Other cellulose fiber sources include:
    • Wood (most common)
    • Flax
    • Hemp
    • Straw
    • Cotton
    • Bamboo
• Special Trees:
  • High-quality cellulose fibers come from wood (both deciduous and evergreen).
  • Softwoods are favored for their longer fibers, lower cost, and stronger paper.
  • Example: Eucalyptus trees in Thailand for paper production.

Paper Manufacturing Process

• Ingredients:
  • Debarked, chipped wood or other cellulose fibers.
  • Chemicals to break down lignin that binds cellulose (e.g., acetic acid, caustic soda).
  • Fillers (e.g., clay, calcium carbonate) for smooth finish.
  • Brightening agents, such as bleach.
  • Water (typically 500ml to make one A4 sheet).
• Water Usage:
  • Making a ream (500 sheets) of photocopy paper requires approximately 250 liters of water.

Sizing and Paper Qualities

• Sizing: Reduces absorbency in the paper.
  • Internal sizing added during pulp processing influences paper quality.
  • Surface sizing added later enhances strength and printability.
• Paper Qualities:
  • Whiteness: Brightness level.
  • Opacity: Transparency.
  • Strength: Tear resistance.
  • Absorbency: Resistance to ink/water soaking.