Wet end chemistry ch 12
WPS, CBNU
Reasons for sizing paper
• Strong natural tendency to interact with water
• Important properties to the development of strong interfiber hydrogen bonds during papermaking and to strength loss when saturated with water
• Liquid (water) penetration resistance by sizing
Two types of sizing processes
• Sizing: impart resistance to water penetration in paper
• Surface sizing and internal sizing
• Surface sizing: the paper web is formed and dried and a sizing agent is applied to the paper surface by a size press
• Internal sizing: sizing additives are added to the papermaking furnish and get incorporated into the web when it is formed.
Some sizing terminology
• Waterleaf papers: very absorbent papers which have no water
resistance
• Slack sized papers: papers that have intermediate levels of water resistance
• Hard sized papers: highly water resistant paper
• Fugitive sizing: the disappearance of liquid penetration resistance after it is manufactured
• Self sizing: the gradual development of water resistance in a paper that does not have after being manufactured
Basic surface science considerations
important to sizing
• Four ways that liquid penetrates paper
– 1)capillary flow in pores: the Washburn equation
– 2)diffusion through pores
– 3)diffusion through fiber solid fractions
– 4) evaporation, vapor phase diffusion, and condensation
Wet end chem chapter 13
WPS
CBNU
Wet end chem chapt 14
Wood and Paper Science
Chungbuk National University