FAIR-CT95-0312 Heat Induced Yellowing - A Secondary Phenomena of Chlorine-Free Bleaching

Contacts
Further Information



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FAIR Area 1.3 - Forestry-Wood Chain : Paper/Pulp : Pulping : Wood (Lignocellulose)

	Type of Project	Shared Cost
	Contract No	FAIR-CT95-0312
	Total Cost	810 ECU
	EC Contribution	510 ECU
	Start Date	01/1/1995
	Duration	36 months

Heat-induced yellowing - a secondary phenomenon of chlorine-free bleaching

Objectives

Technical Approach

The broad application of totally chlorine-free bleached (TCF) pulps in the paper industry is limited by their low thermal stability. Therefore, the objective of this project is to study the formation of discoloured products in the course of heating of TCF-bleached pulps. This includes the investigation of the reactions occurring during thermal treatment of such pulps and the development of countermeasures against the yellowing process. As the consequence, the competitiveness of the TCF-pulps should be improved and the TCF-bleaching processes made more attractive.

Expected Results

I Direct Results

Provision of sufficient information about mechanisms of the heat-induced yellowing and tools to improve the thermal stability of TCF-bleached pulps by:

• investigating the interdependencies between bleaching parameters and yellowing intensity
• studying the effect of external and structural parameters of the pulps on their discoloration
• investigating changes of the polymer properties of the cellulose during bleaching and heating
• identifying chromophore structures and the paths in which they are formed
• chemical derivatisation as a tool for mechanistic investigations
• optimisation of methodology and application of the analysis of functional groups in the pulps
• optimisation of the bleaching with respect to high brightness and thermal stability of the pulps
• use of stabilising additives

II. Indirect Results

• Better understanding of chemical reactions of polysaccharide chains under high temperatures
• Improvement of analysis of functional groups in polysaccharide polymers

Applications

All pulp producers who are interested in the production of TCF pulps can apply the countermeasures against thermal yellowing of TCF pulps. The results could be of special interest to subsequent producers of furnishing materials and polymer coated wallpapers, where the paper undergoes a further high-temperature processing.

Heat-induced discoloration of chlorine-free bleached pulps

Contacts

Coordinator

• Prof Klaus Fischer / Dresden University of Technology Institute of Plant and Wood Chemistry / GERMANY

EC Scientific Officer

• Ignacio SEOANE / European Commission DG Research Theme 1 Key Action 5.3 / BELGIUM

Participant

• Prof Dominique LACHENAL / Centre Technique de l'Industrie des Papiers, Cartons et Celluloses / FRANCE
• Finnish Pulp & Paper Research Institut OY Keskuslaboratorio / FINLAND
• Kosti KUKKONEN / Metsa-Serla Chemicals OY Oy Metsa-Botnia, Kaskinen Pulp Mill / FINLAND