Slipsheet, divider sheet and method for making the same

Abstract

The present disclosure provides a slipsheet and/or divider sheet and method for making the same, and method for moving and storing containers with use of the slipsheets or divider sheets. The sheets have an imprint or an embossing that provides a raised planar surface. The raised planar surface preferably comprises a plurality of ridges, crowns or crests, which are preferably arranged in a pattern throughout an upper surface of the sheet. To make the sheet, a die can be etched to have protuberances or bumps, and the die is preferably pressed into a sheet of pliable thermoplastic material. The sheet thus made has a plurality of indentations formed by the protuberances or bumps on the die, and the sheet has a planar outer surface comprising a plurality of ridges, crowns and crests between the indentations.

What is claimed is: 
     
       1. A method for making a slipsheet, comprising the steps of:
 extruding a first sheet comprising high density polyethylene; 
 extruding a second sheet comprising linear low density polyethylene; and 
 passing the first and second sheets through a plurality of rollers, thereby forming a single unitary sheet having a top surface and a bottom surface, 
 wherein one of the plurality of rollers comprises an indented surface having a plurality of indentations, and the indented surface of the roller is adapted to impart a raised surface on the top surface of the single unitary sheet, and 
 wherein the indentations have a size adapted to provide a desired coefficient of friction of the raised surface that is less than a coefficient of friction of the bottom surface of the single unitary sheet. 
 
     
     
       2. The method of  claim 1 , wherein the step of extruding the first sheet and the step of extruding the second sheet are performed by co-extrusion. 
     
     
       3. The method of  claim 2 , wherein each of the rollers within the plurality of rollers are arranged vertically relative to the other rollers. 
     
     
       4. The method of  claim 2 , wherein each of the rollers within the plurality of rollers are arranged horizontally relative to the other rollers. 
     
     
       5. The method of  claim 2 , wherein a first sheet extrusion die and a second extrusion die are placed one above the other with linear low density polyethylene extruded and fed to an upper die and high density polyethylene fed to a lower die. 
     
     
       6. The method of  claim 2 , wherein the plurality of rollers comprises a first roller which has a smooth surface, a second roller which has a surface comprising a plurality of protuberances and a plurality of recesses, and a third roller which has a smooth surface, and wherein the second roller is located between the first roller and the third roller. 
     
     
       7. The method of  claim 6 , wherein the plurality of rollers press the first and second sheets together and form a single unitary sheet, the plurality of recesses on the surface of the second roller form raised surfaces on the top surface of the single unitary sheet, and the plurality of protuberances on the surface of the second roller form recessed surfaces on the top surface of the single unitary sheet. 
     
     
       8. The method of  claim 2 , wherein the linear low density polyethylene sheet is fed to a co-extrusion box in a line between a HDPE extruder and a single sheet extrusion die. 
     
     
       9. The method of  claim 2 , wherein the linear low density polyethylene sheet is fed immediately upstream of a single sheet extrusion die, which also receives a high density polyethylene sheet that has been extruded. 
     
     
       10. The method of  claim 6 , wherein the plurality of rollers are arranged vertically with the second roller below the first roller and the third roller below the second roller. 
     
     
       11. The method of  claim 6 , wherein the plurality of rollers are arranged horizontally with the second roller below the first roller and the third roller below the second roller. 
     
     
       12. The method of  claim 7 , wherein the bottom surface comprises a recessed surface and a grid of ridges, wherein the recessed surface comprises a plurality of indentations arranged in a pattern. 
     
     
       13. The method of  claim 12 , wherein the raised surface is relatively smooth in comparison to the bottom surface. 
     
     
       14. A method for making a slipsheet, comprising:
 co-extruding a unitary sheet of plastic comprising a first sheet comprising high density polyethylene and a second sheet comprising low density polyethylene, wherein the unitary sheet has a top surface and an opposing bottom surface; and 
 passing the unitary sheet of plastic through a plurality of rollers, wherein the plurality of rollers press the first sheet and the second sheet together, wherein at least one of the plurality of rollers comprises an indented surface adapted to impart a raised surface on the top surface of the unitary sheet and further wherein the indented surface is adapted to provide a desired coefficient of friction value of the raised surface that is less than a coefficient of friction of the bottom surface the unitary sheet. 
 
     
     
       15. The method according to  claim 14  further comprising the step of providing a plurality of extrusion dies arranged vertically with respect to each other with low density polyethylene fed to an upper one of the plurality of extrusion dies and high density polyethylene fed to a lower one of the plurality of extrusion dies. 
     
     
       16. The method according to  claim 14  wherein the plurality of rollers comprises a first roller having a smooth surface, a second roller having a plurality of protuberances and a plurality of recesses, and a third roller having a smooth surface. 
     
     
       17. The method according to  claim 16  wherein the second roller is located between the first roller and the third roller. 
     
     
       18. The method according to  claim 14  wherein the recessed surface is smoother than the bottom surface. 
     
     
       19. The method according to  claim 18  wherein the bottom surface comprises a plurality of ridges and a plurality of indentations. 
     
     
       20. A slipsheet made according to the method of  claim 1 . 
     
     
       21. A slipsheet made according to the method of  claim 14 . 
     
     
       22. A slipsheet or divider sheet comprising a sheet of material adapted to support a load, wherein the sheet of material comprises:
 a thermoplastic material;   four edges defining a perimeter of the sheet of material, wherein the four edges comprise a first edge, a second edge, a third edge, and a fourth edge;   a first surface and a second surface, wherein:   the first surface has a first coefficient of friction and the second surface has a second coefficient of friction, wherein the first coefficient of friction is lower than the second coefficient of friction;   the first surface is opposing the second surface; and   the first surface comprises a support surface, wherein the support surface is:   adapted to support goods, boxes, packages, or containers; and comprises a recessed surface having an imprinted pattern of indentations and a raised surface having a pattern of raised surfaces.    
     
     
       23. The slipsheet or divider sheet according to claim 22, wherein the pattern of raised surfaces comprises a plurality of protuberances projecting from at least a portion of the first surface of the sheet of material, wherein the plurality of protuberances are arranged in a series of rows.  
     
     
       24. The slipsheet or divider sheet according to claim 23, wherein the series of rows forming the plurality of protuberances extend from the first edge to the second edge along at least a portion of the first surface at an angle that is not orthogonal to the first edge or the second edge.  
     
     
       25. The slipsheet or divider sheet according to claim 24, wherein:
 the first edge and the third edge are parallel; and   the second edge and the fourth edge are parallel.    
     
     
       26. The slipsheet or divider sheet according to claim 23, wherein the imprinted pattern of indentations comprises grooves extending in between the rows forming the plurality of protuberances.  
     
     
       27. The slipsheet or divider sheet according to claim 22, wherein the recessed surface further comprises a transition or intermediate surface located between a lowermost surface and an uppermost surface.  
     
     
       28. The slipsheet or divider sheet to claim 22, wherein the raised surface comprises a majority of the first surface.  
     
     
       29. The slipsheet or divider sheet according to claim 22, wherein the pattern of raised surfaces provides rigidity to the first surface.  
     
     
       30. The slipsheet or divider sheet according to claim 22, wherein the sheet of material comprises a first layer and a second layer, wherein at least one of the first layer and the second layer comprise high density polyethylene.  
     
     
       31. The slipsheet or divider sheet according to claim 30, wherein the at least one of the first layer and the second layer comprises high density polyethylene and the other comprises linear low density polyethylene.  
     
     
       32. The slipsheet or divider sheet according to claim 22, wherein the divider sheet has a thickness of from 1 millimeter to 5 millimeters.  
     
     
       33. The slipsheet or divider sheet according to claim 22, wherein the raised surface comprises a plurality of crowns.  
     
     
       34. The slipsheet or divider sheet according to claim 22, wherein the raised surface comprises a plurality of crests.  
     
     
       35. The slipsheet or divider sheet according to claim 33, wherein the plurality of crowns defines an outermost surface of the first surface.  
     
     
       36. The slipsheet or divider sheet according to claim 34, wherein the plurality of crests defines an outermost surface of the first surface.  
     
     
       37. The slipsheet or divider sheet according to claim 22, wherein the sheet of material has a first tear strength in a first direction and a second tear strength in a second direction, and the first tear strength is greater than the second tear strength.  
     
     
       38. The slipsheet or divider sheet according to claim 22, wherein the support surface comprises a grid-like or net-shaped structure or discrete and discontinuous structures.  
     
     
       39. The slipsheet or divider sheet according to claim 22, wherein the recessed surface comprises a grid-like or net-shaped structure or discrete and discontinuous structures.  
     
     
       40. The slipsheet or divider sheet according to claim 22, wherein the raised surface comprises a grid-like or net-shaped structure or discrete and discontinuous structures.  
     
     
       41. The slipsheet or divider sheet according to claim 22, wherein the sheet of material is made from recyclable material.  
     
     
       42. The slipsheet or divider sheet according to claim 22, wherein the sheet of material is recyclable.  
     
     
       43. The slipsheet or divider sheet according to claim 22, wherein the sheet of material is rectangular.  
     
     
       44. A slipsheet or divider sheet comprising a sheet of material adapted to support a load, wherein the sheet of material comprises:
 a thermoplastic material;   four edges defining a perimeter of the sheet of material, wherein the four edges comprise a first edge, a second edge, a third edge, and a fourth edge; and   a first surface and a second surface, wherein:   the first surface has a first coefficient of friction and the second surface has a second coefficient of friction, wherein the first coefficient of friction is lower than the second coefficient of friction;   the first surface is opposing the second surface; and   the first surface comprises a support surface;   wherein the support surface comprises a pattern comprised of a plurality of rows of indentations and a plurality of rows of raised surfaces, wherein: the plurality of rows of indentations extend in between the plurality of rows of raised surfaces; and the plurality of rows of raised surfaces extend from the first edge to the second edge along at least a portion of the first surface at an angle that is not orthogonal to the first edge or the second edge.    
     
     
       45. The slipsheet or divider sheet according to claim 44, wherein the raised surfaces comprise a plurality of protuberances projecting from at least a portion of the first surface of the sheet of material.  
     
     
       46. The slipsheet or divider sheet according to claim 45, wherein the plurality of rows of indentations comprise grooves extending in between the plurality of protuberances.  
     
     
       47. The slipsheet or divider sheet according to claim 46, wherein the plurality of rows of indentations comprise a grid-like or net-shaped structure.  
     
     
       48. The slipsheet or divider sheet according to claim 46, wherein:
 the first edge and the third edge are parallel; and   the second edge and the fourth edge are parallel.    
     
     
       49. The slipsheet or divider sheet according to claim 47, wherein the plurality of protuberances defines an outermost surface of the first surface.  
     
     
       50. The slipsheet or divider sheet according to claim 45, wherein the raised surfaces comprise a majority of the first surface.  
     
     
       51. The slipsheet or divider sheet according to claim 44, wherein the plurality of rows of raised surfaces provides rigidity to the first surface.  
     
     
       52. The slipsheet or divider sheet according to claim 44, wherein the sheet of material has a first tear strength in a first direction and a second tear strength in a second direction, and the first tear strength is greater than the second tear strength.  
     
     
       53. The slipsheet or divider sheet according to claim 44, wherein the slipsheet comprises a first layer and a second layer, wherein at least one of the first layer and the second layer comprise high density polyethylene.  
     
     
       54. The slipsheet or divider sheet according to claim 53, wherein the at least one of the first layer and the second layer comprises high density polyethylene and the other comprises linear low density polyethylene.  
     
     
       55. The slipsheet or divider sheet according to claim 44, wherein the sheet of material has a thickness of from 1 millimeter to 5 millimeters.  
     
     
       56. The slipsheet or divider sheet according to claim 44, wherein the sheet of material is made from recyclable material.  
     
     
       57. The slipsheet or divider sheet according to claim 44, wherein the sheet of material is recyclable.  
     
     
       58. The slipsheet or divider sheet according to claim 44, wherein the sheet of material is rectangular.  
     
     
       59. The slipsheet or divider sheet according to claim 44, wherein the four edges can be gripped by a push pull device.