Plastic corrugated container with sealed edges

Abstract

A reusable plastic container is provided. The container includes a plastic container body having opposing side panels and opposing end panels. The container body also includes top side panel flaps attached to a top portion of each side panel, and bottom side panel flaps attached to a bottom portion of each side panel. The container body has top end panel flaps attached to a top portion of each end panel, and bottom end panel flaps attached to a bottom portion of each end panel. The top and bottom side panel flaps are each defined with respect to the side panels by a fold line. The fold lines including at least one scored portion and at least one welded portion.

Claims

1. A plastic corrugated container comprising: a plurality of plastic corrugated panels forming a container body, each panel having a first planar layer, a second planar layer and a plurality of parallel flutes disposed therebetween extending from a first edge of the first planar layer and a first edge of the second planar layer at a first end of the panel to a second edge of the first planar layer and a second edge of the second planar layer at an opposing second end of the panel, wherein first edges of the plurality of flutes span from the first edge of the first planar layer to the first edge of the second planar layer and are perpendicular to the first planar layer and the second planar layer; and a first smooth and arcuate sealed surface having a C-shape without inflexion and connecting the first planar layer and the second planar layer and having no core material, the surface having been formed from the first and second layers without fully melting any of the first planar layer and the second planar layer at the first edge of the first planar layer and the first edge of the second planar layer across the plurality of parallel flutes of at least one panel of the plurality of panels proximate the first end of the at least one panel.

2. The plastic corrugated container of claim 1 further comprising a second sealed surface formed at a second edge across the plurality of parallel flutes of the at least one panel proximate the second end of the at least one wall panel.

3. The plastic corrugated container of claim 1 wherein the plurality of panels are integrally connected.

4. The plastic corrugated container of claim 1 wherein the at least one panel includes a lower bottom flap portion and wherein the first edge is part of the bottom flap portion.

5. The plastic corrugated container of claim 4 wherein the lower bottom flap portion is connected to a wall panel portion of the at least one panel by a fold line.

6. The plastic corrugated container of claim 5 wherein the at least one panel includes an upper top flap portion and wherein the second edge is part of the top flap portion.

7. The plastic corrugated container of claim 6 wherein the upper top flap portion is connected to the wall panel portion of the at least one panel by a fold line.

8. The plastic corrugated container of claim 7 wherein each of the plurality of panels includes a lower bottom flap portion having a smooth sealed edge across the plurality of parallel flutes of each panel.

9. The plastic corrugated container of claim 8 wherein each of the plurality of panels includes an upper top flap portion having a smooth sealed edge across the plurality of parallel flutes of each panel.

10. The plastic corrugated container of claim 1 wherein each of the panels has a thickness of approximately 2-10 mm.

11. The plastic corrugated container of claim 1 includes approximately 67-100 flutes per foot.

12. A flap of a plastic corrugated container comprising: a first planar plastic layer, a second planar plastic layer and a plurality of plastic flutes disposed therebetween, the plurality of plastic flutes extending to a first edge of the first planar plastic layer and a first edge of the second planar plastic layer, wherein first edges of the plurality of plastic flutes span from the first edge of the first planar plastic layer to the first edge of the second planar plastic layer and are perpendicular to the first planar plastic layer and the second planar plastic layer and wherein the first planar plastic layer, the second planar plastic layer and flutes extending from a first smooth and arcuate sealed surface across the plurality of plastic flutes to a fold line, the first smooth surface is formed from the first and second layers without fully melting any of the first planar plastic layer and the second planar plastic layer and the first smooth surface having a C-shape without inflexion and connecting the first planar layer and the second planar layer and having no core material.

13. The flap of claim 12 wherein the first smooth sealed edge is formed by contact with a heat sealing bar having a C-shaped cross-section across the plurality of plastic flutes.

14. The flap of claim 12 wherein the flap includes approximately 67-100 flutes per foot.

15. The flap of claim 12 wherein the flap forms a portion of a bottom of a rectangular box container.

16. The flap of claim 12 wherein the flap forms a portion of a top of a rectangular box container.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) To understand the present invention, it will now be described by way of example, with reference to the accompanying Figures in which:

(2) FIG. 1 is a plan view of a plastic corrugated blank having fold lines of an embodiment of the present invention.

(3) FIG. 2 is an enlarged view of section 2 of FIG. 1 showing the scored portion and welded portion of a fold line of an embodiment of the present invention.

(4) FIG. 3 is a perspective view of a welded portion of a fold line of an embodiment of the present invention.

(5) FIG. 4 is a perspective view of a scored portion of a fold line of an embodiment of the present invention.

(6) FIG. 5 is a partially erected plastic corrugated container of an embodiment of the present invention.

(7) FIG. 6 is a plan view of a plastic corrugated blank having fold lines of an embodiment of the present invention.

(8) FIG. 7A is a schematic view of an apparatus for making a plastic corrugated blank in accord with an embodiment of the present invention.

(9) FIG. 7B is a schematic view of an apparatus for making a plastic corrugated blank in accord with an embodiment of the present invention.

(10) FIG. 8A is a schematic view of an apparatus for making a plastic corrugated blank in accord with an embodiment of the present invention.

(11) FIG. 8B is a schematic view of an apparatus for making a plastic corrugated blank in accord with an embodiment of the present invention.

(12) FIG. 9A is a schematic view of an apparatus for making a plastic corrugated blank in accord with an embodiment of the present invention.

(13) FIG. 9B is a schematic view of an apparatus for making a plastic corrugated blank in accord with an embodiment of the present invention.

(14) FIG. 10 is a schematic view of an apparatus for making a plastic corrugated blank in accord with an embodiment of the present invention.

(15) FIG. 11A is a schematic view of a tab and cutout in a plastic corrugated blank in accord with an embodiment of the present invention before engagement.

(16) FIG. 11B is a schematic view of a tab and cutout in a plastic corrugated blank in accord with an embodiment of the present invention after engagement

(17) FIG. 12 is a perspective of a stack of pre-erected containers for use with a packaging erector machine.

(18) FIG. 13 is a perspective view of a stack of partially constructed and/or broken down containers for use with a packaging erector machine.

DETAILED DESCRIPTION OF THE INVENTION

(19) While this invention is susceptible of embodiments in many different forms, there is shown in the Figures, and will herein be described in detail, preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention, and is not intended to limit the broad aspect of the invention to the embodiments illustrated.

(20) Referring to the drawings, in an embodiment of the present invention shown in FIG. 5, an erected and partially set up plastic corrugated box or container 10 is provided. The container 10 includes a container body 12 having a first end panel 14 and a second end panel 16, and a first side panel 18 and a second side panel 20. The first and second end panels 14 and 16 each have top portions 22 and bottom portions 24. The first and second side panels 18 and 20 also each have top portions 26 and bottom portions 28.

(21) Bottom end panel flaps 30 are attached to the bottom portions 22 of the first and second end panels 14 and 16 along fold lines 32. Top end panel flaps 34 are attached to the top portions 22 of the first and second end panels 14 and 16 along fold lines 36. Bottom side panel flaps 38 are attached to the bottom portions 28 of the first and second side panels 18 and 20 along fold lines 40. Top side panel flaps 42 are attached to the top portions 26 of the first and second side panels 18 and 20 along fold lines 43.

(22) The container 10 is formed from a plastic blank 44 shown in FIGS. 1 and 2. The blank 44 is an extruded sheet of plastic having a first layer 66 and a second layer 68, and a plurality of flutes 70 between them. (See FIGS. 3 and 4). The blank 44 includes the first end panel 14 having a first end 46 and a second end 48. The first side panel 18 has a first end 50 and a second end 52. The first end 50 of the first side panel 18 is attached to the second end 48 of the first end panel 14. The second end panel 16 has a first end 54 and a second end 56. The first end 54 of the second end panel 16 is attached to the second end 52 of the first side panel 18. The second side panel 20 includes a first end 58 and a second end 60.

(23) The first end 58 of the second side panel 20 is attached to the second end 56 of the second end panel 16. In this pre-erected position, the bottom and top side and end panel flaps 30, 34, 38 and 42 are substantially planar with respect to their respective side and end panels 14, 16, 18 and 20. The bottom and top side and end panel flaps 30, 34, 38 and 42 are folded into an erected position to create the container 10. FIG. 5 shows a partially erected container 10 with the bottom side and end panel flaps 30 and 38 folded and the top side and end panel flaps 34 and 42 not yet folded. In a fully erected position, the top side and end panel flaps 34 and 42 are folded to enclose the container 10. After the container 10 is used, it is knocked down to a pre-erected (totally flat) or a partially broken down (one end of the blank still attached to the other end) position for transport and storage.

(24) In one embodiment, a tab 62 is attached to the second end 56 of the second side panel 16. The tab 62 engages with a cutout 64 in the first end 46 of the first end panel 14. The tab 62 and cutout 64 are sized and shaped such that when engaged, as shown in FIGS. 11A and 11B, the tab 62 and cutout 64 form a connection between the first end panel 14 and second side panel 20 such that the panels are substantially coplanar as shown in FIG. 11B, and do not add thickness to the wall sections at this point. This becomes important when a large number of partially constructed or broken down containers are stacked (or positioned side by side) for a container erecting machine (See FIG. 12). Even a slight increase in thickness (above the double wall thickness of the remainder of the collapsed container) would result in a bulge in this area that could cause problems with the machinery.

(25) In another embodiment, the tab or manufacturers joint flap 62 can be extruded to a thickness of approximately the thickness of the second side panel 20. Where the tab or manufacturers joint flap 62 and side panel 20 overlap can be fastened, such as by gluing, and welded to a thickness equal to or less than the thickness of the side panel 20 to remove the memory from the plastic, and provide a container 10 with coplanar end and side panels. This does not add thickness allowing the container 10 to work with existing paper corrugated packaging machinery. This embodiment does not require a cutout 64. The tab or manufacturers joint flap 62 may extend the length of the second end 60 of the second end panel 20.

(26) The blank 44 is preferably a corrugated plastic sheet. The blank 44 includes a first layer 66 and a second layer 68. Between the first layer 66 and second layer 68 are flutes 70. The blank 44 is formed as a single, integral sheet, preferably by an extrusion process. Plastic corrugated containers can be made to suit particular size, stiffness, resilience, and strength requirements by varying a variety of characteristics or parameters, such as the thickness of the first and second layers 66 and 68, the overall thickness of the blank 44, the number of flutes 70, the plastic resin used, or other characteristics of the blank 44 material. Typical ranges for such parameters include 67-100 flutes per foot, blank thickness of 2 to 10 mm, and plastic material density of 400 to 1,000 grams per square meter. Typical materials for the blank 44 can include plastic materials such as high density polypropylene and high density polyethylene.

(27) Scored fold lines are known in the art and have been used extensively with paperboard containers such as cardboard. Scored fold lines are typically formed by crushing or partially crushing one or both sides of the blank along the desired fold line. This weakens the blank material so that it can be folded along such line. In addition, the crushed score line can include perforations at intervals along its length.

(28) It has been found that given time, the score lines formed in plastic corrugated packaging in this manner have a memory, meaning the material has a tendency to return to its original pre-erected substantially planar position. Over time, typically on the order of days, the memory of the material essentially makes the score lines disappear, making folding the blank along these score lines a second time difficult if not impossible. The material is too stiff to be used in existing automated packaging equipment.

(29) It has also been found that welding the first and second layers 66 and 68 of the blank 44 together allows for easy folding, but substantially negates the memory of the material. Welded score lines have not been previously used in connection with plastic corrugated packaging. Welding only (without providing a scored portion) may hinder the material from being used on existing corrugated paper packaging equipment as the top and bottom side and end panel flaps will not return to their pre-erected substantially planar configuration with the side and end panels (See FIG. 13).

(30) To overcome this problem, a combination of welding and scoring the fold lines of the present invention is used. This provides the desired combination of ease of foldability and memory to permit the top and bottom side and end panel flaps to be folded and return to substantially their pre-erected planar configuration with the side and end panels after use and knock down. Thus, plastic packaging made in accord with the present invention can be reused and can be erected again using existing packaging equipment.

(31) To this end, the fold lines 32, 26, 40 and 43 include at least one welded portion 72 (FIG. 3) and at least one scored portion 74 (FIG. 4). Additional welded portions 72 and/or scored portions 74 can be used for each fold line. In an embodiment shown in FIGS. 1, 2, 5 and 6, scored portions 74 are located at the first and second ends 50, 52, 58 and 60 of the side panels 18 and 20, and the first and second ends 46, 48, 54 and 56 of the end panels 14 and 16.

(32) The scored portions 74 can be sized and spaced along the fold lines 32, 36, 40 and 43 to achieve desired foldability and memory characteristics such that the bottom and top end and side panel flaps 30, 34, 38 and 42 return to their substantially pre-erected position to allow it to be used with existing packaging equipment. The scored portions 74 can be crushed and may include perforations. The remainder of the fold lines 32, 36, 40 and 43 between the scored portions 74 include welded portions 72.

(33) As an example, in a plastic corrugated container 10 having dimensions 12 inches wide by 20 inches long by 8 inches high, and made of a material high density polypropylene, having a blank 44 thickness of 3-4 mm, and ninety flutes 70 per foot, it has been found that scored portions of approximately 1 inches in length at the first and second ends 46, 48, 50, 52, 54, 56, 58 and 60 of the side and end panels 14, 16, 18 and 20 provides the desired characteristics. For longer side panels 18 and 20 as shown in FIG. 6, additional scored portions 74 can be located along the length of the fold lines 32, 36, 40 and 43. Alternatively, the scored portions 74 can be of longer or shorter length to achieve the same desired result. The same is true of the shorter end panels 14 and 16 of FIG. 6, wherein only one scored portion 74 may be desired or necessary.

(34) The welded portion 72 and scored portion 74 are formed using an apparatus 76, which includes a bottom platen 78 and a top platen 80. In one embodiment shown in FIGS. 7A and 7B, the top platen 80 includes a rule 82. FIG. 7A shows the apparatus before fold lines 32, 36, 40 and 43 are formed in the blank 44. FIG. 7B shows the blank 44 are the fold lines are formed. The rule 82 includes a weld-forming portion 84 and score-forming portion 86. The score forming portion 86 is recessed with respect to the weld-forming portion 84.

(35) For the welded portions 72 of the fold lines 32, 35, 40 and 43, the rule 82 is heated by a heating element or heater 88. The heater 88 heats the rule 82 to a temperature sufficient to form a welded portion 72 along the fold lines 32, 36, 40 and 43. This temperature will depend at least in part on the material used. Alternately, the bottom platen 78 can be heated at portions aligning with the weld-forming portions 84 of the rule 82 to the same effect. The rule 82 can include serrations in the score-forming portion 86.

(36) In operation, the bottom platen 78 remains stationary while the top platen 80 is moved in a vertical direction. The blank 44 is placed between the bottom platen 78 and top platen 80. The top platen 80 including the rule 82 is lowered. The rule 82 contacts the blank 44. The weld-forming portion 84 welds the first layer 66 of the blank 44 to the second layer 68. The score-forming portion 86, since it is recessed from the weld-forming portion 84, forms the scored portion 74 of the fold lines 32, 36, 40 and 43.

(37) FIGS. 8A and 8B are similar to FIGS. 7A and 7B, but show an embodiment where scored portions 74 and welded portions 72 are formed alternately at selected desired intervals along the fold lines 32, 36, 40 and 43 as shown in the blank 44 of FIG. 6. This embodiment may be desirable where, for instance, the length of the side panels 18 and 20 and end panels 14 and 16 of the container 10 and blank 44 is such that the return strength of these panels is sufficient to return flaps 30, 24, 38 and 42 to substantially their pre-erected position.

(38) FIG. 9A shows an embodiment where the bottom platen 78 rather than the top platen 80 is heated as shown in FIGS. 7A, 7B, 8A, and 8B. FIG. 9B shows an embodiment where both the top and bottom platens 78 and 80 are heated, including the rule 82.

(39) FIG. 10 shows an apparatus 96 for sealing an end 98 of the bottom and top side and end flaps 30, 34, 38 and 42. Sealing is desirable in certain applications such as transport and storage of food items. Sealing prevents food materials from lodging in the interstices of the flutes 70, and bacteria from growing therein. The apparatus 96 includes a heated sealing bar 100 with a generally C-shaped section 102. The heated sealing bar 100 contacts the end 98 of a flap 30, 34, 38 or 42 and partially melts the end 98 to seal it and create a smooth arcuate surface. In the past, heat scoring was used to seal the edges. However, this produces a sharp edge that can be hazardous to those handling the containers.

(40) While the specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention and the scope of protection is only limited by the scope of the accompanying Claims.