Pulping methods, methods for manufacturing paperboard, and paperboard structures
A pulping method includes chemical cooking of softwood chips to retain a high lignin content of about 18% to about 28% by weight and fiberization of the cooked softwood chips to a low residual wood shive content of at most 15% by weight.
1 . A pulping method comprising:
chemical cooking of softwood chips, whereby after the chemical cooking, a content of original lignin in the cooked softwood chips is in a range from about 18% to about 28% by weight, wherein the chemical cooking comprises at least one of a kraft chemical cooking process, a sulfite chemical cooking process, and a neutral sulfite semi-chemical (NSSC) chemical cooking process, and wherein the softwood chips are treated with mechanical delamination to enhance liquor penetration during the chemical cooking; and
fiberization of the cooked softwood chips to a low residual wood shive content of at most 15% by weight.
2 . The pulping method of claim 1 wherein a resulting pulp of the pulping method comprises at least about 10% by weight softwood fibers.
3 . The pulping method of claim 1 wherein a resulting pulp of the pulping method comprises at least about 20% by weight softwood fibers.
4 . The pulping method of claim 1 wherein a resulting pulp of the pulping method comprises at least about 30% by weight softwood fibers.
5 . The pulping method of claim 1 wherein a resulting pulp of the pulping method comprises at least about 40% by weight softwood fibers.
6 . The pulping method of claim 1 wherein a resulting pulp of the pulping method comprises at least about 50% by weight softwood fibers.
7 . The pulping method of claim 1 wherein a resulting pulp of the pulping method comprises at least about 60% by weight softwood fibers.
8 . The pulping method of claim 1 wherein a resulting pulp of the pulping method comprises at least about 70% by weight softwood fibers.
9 . The pulping method of claim 1 wherein a resulting pulp of the pulping method comprises at least about 80% by weight softwood fibers.
10 . The pulping method of claim 1 wherein a resulting pulp of the pulping method comprises at least about 90% by weight softwood fibers.
11 . The pulping method of claim 1 wherein a resulting pulp of the pulping method comprises at least about 95% by weight softwood fibers.
12 . The pulping method of claim 1 wherein a resulting pulp of the pulping method comprises at least about 98% by weight softwood fibers.
13 . The pulping method of claim 1 wherein a resulting pulp of the pulping method comprises at least about 99% by weight softwood fibers.
14 . The pulping method of claim 1 wherein a resulting pulp of the pulping method comprises about 100% by weight softwood fibers.
15 . The pulping method of claim 1 wherein a resulting pulp of the pulping method has a low residual wood shive content of at most 10% by weight.
16 . The pulping method of claim 1 wherein a resulting pulp of the pulping method has a low residual wood shive content of at most 5% by weight.
17 . The pulping method of claim 1 wherein a resulting pulp of the pulping method has a low residual wood shive content of at most 4% by weight.
18 . The pulping method of claim 1 wherein a resulting pulp of the pulping method has a low residual wood shive content of at most 3% by weight.
19 . The pulping method of claim 1 , further comprising mixing the high lignin content and low residual wood shive content pulp with another pulp to form a blend.
20 . The pulping method of claim 19 , wherein mixed pulp contains at least about 30% by weight of the high lignin content and low residual wood shive content pulp.