Condebelt Board and Paper Drying

Lehtinen, Jukka

doi:10.1080/07373939808917453

Cited by 10 publications

(3 citation statements)

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“…A major part of the improved strength properties obtained by Condebelt drying has been explained by the increased sheet density under the restrained drying condition (Retulainen et al 1998;Lee et al 2003). Lehtinen (1995bLehtinen ( , 1998 has shown that Condebelt-dried sheet has advantages in compressive strength because of the extensive fiber flattening, as well as the flow of lignin and hemicellulose. Recently, Joelsson et al (2020) have shown that softening of high yield pulp fibers by hot-pressing densified the sheet by softening of lignin and produced very high dry and wet tensile strengths.…”

Section: Effect Of Restraint High Temperature Dryingmentioning

confidence: 99%

Influence of fiber composition and drying conditions on the bending stiffness of paper

Ham¹,

Youn

Lee

2020

BioRes

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Changes in thickness, elastic modulus, and bending stiffness were studied for handsheets prepared using different fiber compositions and dried under restraint or unrestraint conditions, when exposed to various humidity conditions. Four sets of experimental studies were carried out to investigate the effect of (1) different amounts of fines (or long fibers), (2) two-ply sheet forming, (3) high temperature restraint press drying, and (4) the use of recycled fibers on the thickness, elastic modulus, and bending stiffness. The results showed that thickness, elastic modulus, and bending stiffness changed depending upon the fiber composition, single or multi-ply forming, drying conditions, and recycling of fibers. Thickness change, restraint drying, and fiber hornification during recycling were the principal factors affecting the bending stiffness in cyclic humidity conditions.

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Section: Effect Of Restraint High Temperature Dryingmentioning

confidence: 99%

Influence of fiber composition and drying conditions on the bending stiffness of paper

Ham¹,

Youn

Lee

2020

BioRes

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“…This technique improves the strength properties at same time, preserves the bulk and bending stiffness. The Condebelt was implemented in some commercial board machines in 1996 [11].…”

Section: Introductionmentioning

confidence: 99%

Unique steel belt press technology for high strength papers from high yield pulp

et al. 2021

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The dry strength properties of hot-pressed moist paper improved as stiff high-yield pulp fibers soften and the sheet density increased. Very high wet strength was also achieved without adding strengthening agents. This research focuses on a new hot-pressing methodology based on a steel belt-based pilot cylinder press with infrared heating. The heated steel belt transports the moist paper into the cylinder nip with two adjacent steel rollers with adjustable nip pressure. The temperature ranges up to 300 °C, maximum speed is 5 m/min, maximum pulling force from the steel belt is 70 kN and the line load in the two press nips is 15 kN/m each. High peak pressures are possible due to the hard press nip between steel rolls and steel belt, allowing a good heat transfer to the paper. The long dwell time allows strained drying of the paper which results to high density and high wet strength. Paper samples from high-yield pulps were tested at different nip pressures, temperatures and machine speeds while the dry content was kept constant at about 63%. High nip pressure showed the largest effect on densification and dry strength. While high temperature and long dwell time seem to be most important in achieving high wet strength.

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“…Typical run parameters for Condebelt are a dwell time of about 1-20 seconds, a pressure of 1.5 to 8 bar and a surface temperature of 120 to 170 C. The Condebelt board shows up to 50% improved strength properties compared to cylinder drying, see Lehtinen [7]. Commercial shoe presses are normally 150 to 300 mm long and the press loads are maximized to 1500 kN/m.…”

Section: Introductionmentioning

confidence: 99%