Multilayer paperboard
AssigneeBillerud Aktiebolag (publ)
InventorJohan Magnusson
Life of this patent
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Abstract
There is provided a multilayer paperboard comprising a top layer, a back layer and a middle layer, wherein: —the middle layer is arranged between the top layer and the back layer; —the top layer is formed from a top layer furnish comprising at least 50% by dry weight softwood kraft pulp; —the middle layer is formed from a middle layer furnish, wherein broke pulp and chemithermomechanical pulp (CTMP) constitutes at least 85% by dry weight of the middle layer furnish, said broke pulp has essentially the same pulp composition as the multilayer paperboard and the average fibre length of said CTMP is equal to or below 1.4 mm as measured according to ISO 16065-2:2014; and —the back layer is formed from a back layer furnish comprising at least 80% by dry weight softwood kraft pulp.
Claims21
A multilayer paperboard comprising a top layer, a back layer and a middle layer, wherein:
- the middle layer is arranged between the top layer and the back layer;
- the top layer is formed from a top layer furnish comprising at least 50% by dry weight softwood kraft pulp;
- the middle layer is formed from a middle layer furnish, wherein broke pulp and chemithermomechanical pulp (CTMP) constitutes at least 85% by dry weight of the middle layer furnish, said broke pulp has essentially the same pulp composition as the multilayer paperboard and the average fiber length of said CTMP is equal to or below 1.4 mm as measured according to ISO 16065-2:2014;
- and
- the back layer is formed from a back layer furnish comprising at least 80% by dry weight softwood kraft pulp.
A method for producing a multilayer paperboard comprising a top layer, a back layer and a middle layer, wherein the method comprises the following steps:
- a. providing a top layer furnish comprising at least 50% by dry weight softwood kraft pulp;
- b. providing a middle layer furnish, wherein broke pulp and chemithermomechanical pulp (CTMP) constitutes at least 85% by dry weight of the middle layer furnish, said broke pulp has essentially the same pulp composition as the multilayer paperboard and the average fiber length of said CTMP is equal to or below 1.4 mm as measured according to ISO 16065-2:2014;
- c. providing a back layer furnish comprising at least 80% by dry weight softwood kraft pulp;
- d. form a top layer from the top layer furnish, a middle layer from the middle layer furnish, and a back layer from the back layer furnish;
- and
- e. form a paperboard from the top layer, middle layer and back layer so that the middle layer is arranged between the top layer and back layer.
(canceled)
Dependencies are inferred from the claim text.