Abstract: Winding cores for elastically stretched or shrinkable materials are designed to significantly reduce the amount of roll strain energy developed during winding. This is accomplished by building into the core an energy-absorbing zone that can be collapsed by a substantial amount and in a relatively controlled fashion over a substantial period of time under the influence of a continued radially inward pressure exerted by the roll of wound material. The energy-absorbing zone is formed by one or more collapsible layers having repeated atomic regions projecting out of a plane of the sheet and each defining a plurality of normal vectors in different sub-regions of the atomic region, wherein the normal vectors, when projected onto the two-dimensional plane of the sheet, are in a plurality of different directions in the plane.

Abstract: A low-density structural panel is made from used paper material such as shredded or divided old corrugated containers (OCC). The pieces of used paper material are mixed with an adhesive and the mixture is formed into a layer. The layer is compressed with a compression device to reduce its thickness and increase its density. The layer is heated to hasten the hardening of the adhesive. The process can be a batch process or a continuous process.

Abstract: A method for reusing used paper material such as paperboard cartons comprises the steps of collecting used paper material after it has been used for its original purpose, dividing the used paper material into pieces without repulping the used paper material, coating an adhesive material onto the pieces, and assembling the coated pieces together into a layer to form a structural panel, the adhesive material binding the pieces together upon curing or drying. The pieces can be long narrow strips and/or shredded pieces and/or fiberized pieces that are essentially randomly oriented in the structural panel.

Abstract: Winding cores for elastically stretched or shrinkable materials are designed to significantly reduce the amount of roll strain energy developed during winding. This is accomplished by building into the core an energy-absorbing zone that can be collapsed by a substantial amount and in a relatively controlled fashion over a substantial period of time under the influence of a continued radially inward pressure exerted by the roll of wound material. The energy-absorbing zone is formed by one or more collapsible layers having repeated atomic regions projecting out of a plane of the sheet and each defining a plurality of normal vectors in different sub-regions of the atomic region, wherein the normal vectors, when projected onto the two-dimensional plane of the sheet, are in a plurality of different directions in the plane.

Abstract: Paper mill cores of the invention are structured to allow winding and unwinding chucks to distort the interior diameter and shape of the interior body wall of the core while resisting distortion of the core exterior to prevent center burst failure. The paper mill cores of the invention include a multi-ply zone of high strength, but relatively compliant, paperboard plies within the outer 70% (based on the total body wall thickness) of the body wall having a thickness of at least about 4 mm. An interior zone constituting at least about 25% of the total thickness of the body wall is formed from extremely high strength, extremely high density paperboard plies. The overall wall thickness of the core is preferably at least about 15 mm, and is thus preferably increased, as compared to the wall thickness of conventional high strength wide paper mill cores formed entirely of extremely high strength, extremely high density, non-compliant paperboard plies.