Composite structural material and method of making the same

A method of making an elongated, composite, structural material, comprising the following steps:

• a) forming a foldable laminate of two strips of porous web material selected from the group consisting of paper and cloth, with at least one strip of a band of reinforcing cords sandwiched there between, with the cords running in the lengthwise direction and with the strips of porous web material and all materials lying between those strips being impregnated with a thermosetting resin-precursor mixture;
• b) folding the laminate into a trough shape and orienting it horizontally, with one of the strips of porous web material on the top and the other strip of porous web material on the bottom;
• c) depositing in the trough of the laminate, while still foldable, a fluid matrix-resin-precursor composition that is compatible with the resin-precursor mixture in the laminate and which, when fully reacted, yields a thermoset matrix resin that is at least semi-rigid;
• d) folding closed and sealing shut the laminate so that it surrounds and defines a core space containing the matrix-resin precursor composition;
• and
• e) holding the closed laminate and its contents in a mold under conditions conducive to the setting of both the thermosetting resin in the laminate and the matrix resin in the core space, for a time sufficient for both resins to sufficiently set that (i) the laminate and the matrix resin are both made at least semi-rigid, (ii) the matrix resin, together with any filler solid it may contain, fills the core space, and (iii) the laminate and matrix resin are bonded together,
• wherein at least one side of the strip of porous web material that is positioned on the bottom is coated with a film of synthetic resin before it is impregnated with the thermosetting-resin-precursor mixture, and the web material is oriented so that its resin-coated side faces down with respect to the horizontal orientation of the trough-shaped laminate during steps b and c, the film of synthetic resin being adequate to substantially prevent any ingredients of the thermosetting-resin-precursor mixture from bleeding through the porous web material.

A method of making an elongated, composite, structural material, comprising the following steps:

• a) forming a foldable laminate of two strips of porous web material selected from the group consisting of paper and cloth, with at least one strip of a band of reinforcing cords sandwiched therebetween, with the cords running in the lengthwise direction and with the strips of porous web material and all materials lying between those strips being impregnated with a thermosetting resin-precursor mixture;
• b) folding the laminate into a trough shape and orienting it horizontally, with one of the strips of porous web material on the top and the other strip of porous web material on the bottom;
• c) depositing in the trough of the laminate, while still foldable, a fluid polyurethane-resin-precursor composition that is compatible with the resin-precursor mixture in the laminate and which, when fully reacted, yields a foamed polyurethane resin that is at least semi-rigid;
• d) folding closed and sealing shut the laminate so that it surrounds and defines a core space containing the polyurethane resin-precursor composition;
• and
• e) holding the closed laminate and its contents in a mold under conditions conducive to the setting of both the thermosetting resin in the laminate and the polyurethane resin in the core space, for a time sufficient for both resins to sufficiently set that (i) the laminate and the foamed polyurethane resin are both made at least semi-rigid, (ii) the foamed polyurethane resin, together with any filler solid it may contain, fills the core space, and (iii) the laminate and foamed polyurethane resin are bonded together,
• wherein the top strip of porous web material is conveyed through a dehumidification zone prior to impregnating it with the thermosetting resin-precursor mixture and prior to forming the foldable laminate in step a.

A shipping pallet comprising:

• a plurality of stringer boards or blocks;
• and
• a plurality of composite upper-deck boards fastened to the stringer boards or blocks, the composite upper-deck boards including two outside-edge boards that flank a plurality of interior boards, each of the composite upper-deck boards comprising a dimensionally stable core material ensheathed in a dimensionally stable covering that is bonded to the core material, the covering comprising rigidified paper with high density polyethylene at a surface of the rigidified paper that is opposite a surface of the rigidified paper that faces the core material,
• wherein the core material of at least one of the upper-deck boards has a lesser crush resistance and lower density than the crush resistance and density of the stringer boards and blocks.