The effect of fibre properties, fines content and surfactant addition on dewatering, wet and dry web properties

Abstract

Speed of paper machines is often limited by the drainage rate of the furnish and the mechanical properties of the wet web, i.e. the tension and relaxation properties. In this study, the effects of alteration of fibre properties and fines content by gentle and harsh refining on dewatering as well as on wet and dry web properties were determined. Both types of refining or addition of fines prolonged the dewatering time but also improved the mechanical properties. Harsh refining with much fibre cutting resulted in longer dewatering time, lower dry content after wet pressing and higher density of dry sheets than gentle refining with much external/internal fibrillation of fibres. Removal of fines shortened the dewatering time but decreased the wet web and dry tensile strength, and the residual tension compared to pulps containing fines. The fibre properties contributed more to the residual tension, while the fines content was more important for the wet web tensile strength. Addition of a non-ionic surfactant shortened the dewatering time of refined pulp without deteriorating the mechanical properties. By tailoring the refining and addition of surfactants, the mechanical properties of the wet web could be improved without prolonging the dewatering time.

Upgrading flax nonwovens: Nanocellulose as binder to produce rigid and robust flax fibre preforms

“…The fibrous network of BC and NFC possesses high tensile strength of 9.7 kN m -1 and 6.6 kN m -1 , respectively [31]. A paper made of pulp fibres, on the other hand, possesses a tensile strength from 1.5-5 kN m -1 [32,33]. This translates to higher measured tensile strengths for the nonwoven preforms with NFC and BC binders compared to the pulp binder.…”

Prospects for Maintaining Strength of Paper and Paperboard Products While Using Less Forest Resources: A Review

“…Surfactants can have either negative or positive effects on paper strength (Touchette and Jenness 1960;Lindqvist et al 2009). Negative effects, when observed, can be attributed partly to a tendency of surfactants to accumulate at phase boundariessome of which are likely to be the potential bonding sites between fibers during the formation of paper.…”

White Water Recirculation Method as a Means to Evaluate the Influence of Fines on the Properties of Handsheets

“…They tried to achieve a constant fines content by producing and discarding 10 handsheets before sheets for mechanical testing were formed. In the study conducted by Lindqvist et al (2012), the method chosen was the one suggested by the Scandinavian Pulp, Paper and Board Committee (SCAN-CM 64:00 (2000)), which also uses a white water recirculation system and links the amount of fines retained in the handsheets with the dewatering time. In this case, the dewatering time must remain constant even when preparing additional sheets.…”

“…They observed changes in the sheet's density and optical properties and a higher anionic charge in the fines fraction compared to that of the long fiber fraction. The addition of secondary fines to the pulp was also shown to negatively affect the dewatering behavior, prolonging dewatering (Lindqvist et al 2012).…”

“…They observed changes in the sheet's density and optical properties and a higher anionic charge in the fines fraction compared to that of the long fiber fraction. The addition of secondary fines to the pulp was also shown to negatively affect the dewatering behavior, prolonging dewatering (Lindqvist et al 2012).The effects of secondary fines on parameters such as dewatering, tensile strength, and porosity differ from those of primary fines. Sirviö et al (2003) and Sirviö and Niskanen (2008) demonstrated that secondary fines are usually of fibrillar nature, which leads to closer fiber contact and enhances fiber-fiber bonding, thereby increasing tensile strength.…”