Patent ID: 8801899

Claim:
An article comprising a ply of paperboard comprising: paperboard fibers which comprise at least about 50% by weight hardwood fibers; a starch paperboard binder, and a paperboard binder coalescing agent in an amount sufficient to cause the starch paperboard binder to coat at least a portion of the paperboard fibers; the paperboard having: a caliper of from about 8 to about 28 points; a basis weight in the range of from about 105 to about 300 lbs/3000 ft 2 ; a MD bending stiffness equal to or greater than a first curve defined by the equation: y 1 =0.5297 x 2.2095 , wherein x is the caliper of the paperboard and y 1 is the MD bending stiffness in Taber Stiffness Units; and a CD bending stiffness equal to or greater than a second curve defined by the equation: y 2 =0.2188 x 2.2681 , wherein x is the caliper of the paperboard and y 2 is the CD bending stiffness in Taber Stiffness Units.