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Z-strength improvement
Boards consist in general of several layers. These layers are often
glued together with a starch-based solvent. The z-strength is a
measure of how strong the final product is in the z-direction. A
popularized description of the z-direction is the “thickness direction”
of the paper, while x- and y-directions denote the surface directions.
Adding starch to a sensitive continuous industrial process is a source
of problems. The risk of starch clogs is obvious. Such clogs will in
many cases cause sheet breaks, with high stop time costs as a
consequence.
By using only high power ultrasound, the Z-strength improvement
solution from Ultra Technology provides the same z-strengths that can
be achieved using starch-based solvents. The applied ultrasound raises
the fibres in the z-direction, in the two layers couched together,
allowing cross-connections between the fibre layers. By this token,
the final board will be stronger and moreover have better converting
features than the starch-glued one. |
