Slip pallet

Abstract

A slip pallet formed as a square or rectangular sheet of a synthetic resin of selected types of polyolefin. The sheet is proportioned to fit upon a platen lift and includes tabs at each edge to be gripped when the platen is thrust underneath the sheet or the sheet is pulled upon or pushed off from the platen. The slip pallet will ordinarily carry loads of boxes formed as interlocking layers and an important feature of the invention resides in providing a sheet having a greater coefficient of friction at the upper surface whereon the boxes are placed, than at the undersurface which is contacted by the platen.

We claim: .[.1. A slip pallet for holding a load of cardboard boxes, or the like, and carried by a platen which slides underneath the slip pallet and its box load for loading and unloading the same onto and off from the platen, said pallet comprising: 
       a tough, pliable sheet of single thickness of synthetic thermoplastic resin having a thickness in the range of approximately 20 to 125 mils; 
       a central area whereon the box load is placed; 
       a tab means alongside at least one edge of this central area folded upwardly along the edge of the central area to be gripped and held whenever the platen is moving underneath the pallet from the tab side; and 
       a modified upper surface at the central area adapted to enhance the contact thereof with the cardboard surfaces of the box load upon the pallet sufficient to increase the static frictional resistance between the box load and the pallet to a degree which exceeds the sliding frictional resistance between the pallet and the platen..]. .[.2. The slip pallet defined in claim 1, wherein: 
       said thermoplastic resin is a polyolefin resin characterized by a tensile strength in the range of 2,500 to 4,500 psi and a vicat softening point temperature in excess of 250° F..]. .[.3. The slip pallet defined in claim 2, wherein: 
       the said modified upper surface is a texture having a roughness such that the coefficient of static friction between the box load and upper surface exceeds the sliding coefficient of friction between the platen and the undersurface of the slip pallet by at least 0.15..]. .[.4. The slip pallet defined in claim 1, wherein: 
       said sheet is a laminate consisting of an upper layer and a lower layer of different synthetic thermoplastic resin materials as a unitary sheet with the material of the upper layer, forming said modified surface, having a natural frictional resistance significantly greater than that of the lower layer..]. .[.5. The slip pallet defined in claim 1, wherein: 
       said sheet is a laminate consisting of an upper layer of fibrous absorbent material and a lower layer of synthetic thermoplastic resin material as a unitary sheet..]. .[.6. The slip pallet defined in claim 2, wherein: 
       the upward tab fold includes a permanent crease at the fold..]. .[.7. The slip pallet defined in claim 2 wherein the thermoplastic resin is polypropylene and the upward tab fold includes a permanent crease at the fold..]. .[.8. The slip pallet according to claim 7 wherein the said modified upper surface is produced by a texture having a roughness not less than approximately 60 micro-inches, the undersurface of the central area is modified by texturing the same to produce a roughness of not over approximately 30 micro-inches, but sufficient to permit air to be present between the pallet and the platen and the coefficient of static friction between the box load and upper surface exceeds the sliding coefficient of friction between the platen and the undersurface of the slip pallet by at least 0.15..]. .[.9. A slip pallet according to claim 1 wherein when in use the coefficient of static friction between the box load and the upper surface exceeds the sliding coefficient of friction between the platen and the under surface of the pallet by at least 0.15..]. .[.10. A combination of the slip pallet of claim 1 with its upper surface supporting a load of cardboard boxes, or the like, and its lower surface being on a platen, and the coefficient of static friction between the box load and the upper surface exceeding the sliding coefficient of friction between the platen and the under surface of the pallet by at least 0.15..]. .Iadd. 11. A reuseable slip pallet adapted to hold a load of cardboard boxes or the like, and to be carried upon a platen which slides underneath the loaded slip pallet to move the slip pallet onto and off of the platen, the platen including a pull-push means to grip an edge of the pallet and to pull and slide the loaded pallet onto the platen and to push and slide the loaded pallet off of the platen; 
       said pallet having a central area whereon the box load is placed; 
       a tab along the side of at least one edge of said central area, partially folded upwardly along the edge of said central area to be gripped and held by the aforesaid gripping means; 
       said pallet being comparatively thin and flexible and thus being yieldable whereby it is subject to rippling and buckling effects when the platen is sliding under the loaded pallet, but is capable of preventing excessive folding or tearing due to such rippling and buckling effects, said pallet being formed of a tough, pliable sheet of single thickness of polyolefin resin having a thickness in the range of approximately 20 to 125 mils, a tensile strength in the range of 2,500 to 4,500 p.s.i. and a vicat softening point temperature in excess of 250° F.; 
       with the aforesaid tab fold being a compression-formed crease in at least one surface of the sheet at the boundary between said central area and said tab and constituting a shallow groove which does not impair the strength of the pallet between said central area and said tab; and 
       a modified upper surface at said central area adapted to increase the static frictional resistance between the box load and the pallet to a degree which exceeds the sliding frictional resistance between the pallet and the platen and wherein the difference in the coefficient of friction between the upper and lower surfaces exceeds 0.15, whereby said pallet will hold the box load without significant slipping between the box load and pallet when the platen is sliding under the pallet. .Iaddend..Iadd. 12. The slip pallet defined in claim 11 wherein said sheet is a laminate consisting of an upper layer and a lower layer of different synthetic thermoplastic resin materials as a unitary sheet with the material of the upper layer, forming said modified surface, having a natural frictional resistance significantly greater than that of the lower layer. .Iaddend. .Iadd. 13. The slip pallet defined in claim 11 wherein said sheet is a laminate consisting of an upper layer of fibrous absorbent material and a lower layer of synthetic thermoplastic resin material as a unitary sheet. .Iaddend..Iadd. 14. The slip pallet defined in claim 11 wherein the thermoplastic resin is polypropylene. .Iaddend..Iadd. 15. A slip pallet according to claim 14 wherein the said modified upper surface is produced by a texture having a roughness not less than approximately 60 micro-inches, the undersurface of the central area is modified by texturing the same to produce a roughness of not over approximately 30 micro-inches but sufficient to permit air to be present between the pallet and the platen. .Iaddend..Iadd. 16. A combination of the slip pallet of claim 11 with its upper surface supporting a load of cardboard boxes or the like, and its lower surface being on a platen, and the coefficient of static friction between the box load and the upper surface exceeding the sliding coefficient of friction between the platen and the undersurface of the pallet by at least 0.15. .Iaddend..Iadd. 17. A slip pallet defined in claim 11 wherein the said modified upper surface is produced by a texture having a roughness of not less than approximately 60 micro-inches. .Iaddend..Iadd. 18. The slip pallet defined in claim 12 wherein the upper layer is polypropylene and the lower layer is polyethylene. .Iaddend.