MXPA98006895A - Container with wall corrug - Google Patents

Abstract

The present invention relates to a container comprising: a bottom wall, and a straight wall which is curved along a circumferential direction joined at a lower edge to the bottom wall, the straight wall includes an inner layer of paper, a outer layer of paper and a central layer of corrugated paper which is sandwiched between the inner layer of paper and the outer layer of paper, and which has undulations through the circumferential direction, at least one of the inner layer of paper and the outer layer of paper has a circumferential plasticity that accommodates changes in the internal and external circumference of the straight wall when the straight wall is curved from a flat preassembled sheet, where the outer paper layer is crepe crepe paper

Description

CONTAINER WITH CORRUGATED WALL FIELD OF THE INVENTION The invention relates, in general, to paper containers and, in particular, to a container having an insulating corrugated paper wall.

BACKGROUND OF THE INVENTION Disposable cups for containing hot beverages can be constructed of expanded polystyrene which provides a relatively low cost glass with walls having good thermal insulation. The insulating properties of the external walls of the vessel allow the vessel to be supported comfortably despite the elevated temperature of its contents. A disadvantage with polystyrene is that it is not biodegradable, easily recycled and can not be subjected to microwaves. On the contrary, paper cups are recyclable and biodegradable but these cups, which use a single sheet of paper for their outer walls, provide little thermal insulation. Therefore, it has been proposed to build the outer wall of a paper cup made of multi-layered corrugated paper material, the air trapped between the corrugating corrugations and the other layers provides sufficient thermal insulation to allow the vessel to be held comfortably. Unfortunately, vessels that use multi-layered corrugated paper material for their external walls are relatively difficult to manufacture.

SUMMARY OF THE INVENTION The present invention provides a paper cup having a corrugated outer wall that can be easily fabricated with conventional cup making machinery in a single cycle process. The pieces of paper or sheets are cut from a special multilayer corrugated cardboard having at least one layer with plasticity in a circumferential direction, allowing the corrugated material to be wrapped around a glass forming mandrel without crushing or deformation of the glass. central corrugated layer. Conventional techniques for winding the rim of the vessel and attaching the bottom or bottom of the vessel with a laminated seam are made practical by limited crushing of the corrugated layer near the upper and lower edge of the external wall significantly improving the capacity of the multiple material. layers to be rolled or rolled without rips. Specifically, the present invention provides a container having a bottom wall and a straight, curved wall along a circumferential direction for attaching to a bottom edge for the bottom wall. The straight wall includes an inner paper layer, an outer paper layer and a corrugated paper layer at the center sandwiched between the inner paper layer and the outer paper layer and has corrugations that cross the circumferential direction. At least the inner paper layer or outer paper layer is constructed of a material having circumferential plasticity that accommodates changes in the inner and outer circumference of the straight wall when the straight wall is bent from a pre-assembled flat sheet. These paper layers can be, for example, a pleated paper layer, an expandable paper layer or a stamped layer that can be stretched or compressed. In this way, an object of the invention is to provide a corrugated material that can be easily formed in a vessel in a single cycle process. The plasticity of the paper layer allows the layers of paper to expand or compress in circumference as necessary for the operation of the winding. The lower edge of the straight wall can be compressed so that the corrugated paper layer is flattened and the lower wall is joined to the lower edge by winding the lower edge around a projection on the bottom wall. The upper edge of the straight wall can also be flattened and rolled into a flange. In this way, another object of the invention is to allow conventional cup assembly techniques with a multi-layered corrugated material to be used. By flattening the corrugations in the winding area, the stretching of the paper in the winding process is minimized, thereby reducing the tear. The crushed corrugated layer also allows for greater sliding between the inner and outer paper layers reducing the damage of the cutting forces inside the rolled paper. The above and other objects and advantages of the invention will be apparent from the following description. In this description reference is made to the accompanying drawings which form a part thereof and in which a preferred embodiment of the invention is shown by way of illustration. This embodiment does not necessarily represent the full scope of the invention, however, and reference should therefore be made to the claims to interpret the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a vessel manufactured in accordance with the present invention in partial section showing a layer of external paper peeled off to show an internal corrugated layer; Figure 2 is a plan view of a sheet of corrugated material before winding to form the vessel of Figure 1 showing the direction of winding, and an axis of corrugation undulations and showing the area where the corrugations are flattened for winding; Figure 3 is a section of a section through the sheet of Figure 2 in a first embodiment showing a layer of pleated outer paper; Figure 4 is a Figure similar to that of Figure 3 after performing the curvature necessary to construct the vessel of Figure 1, and expanding the outer layer to allow this curvature; Figure 5 is a section of a fragment taken along line 5-5 of Figure 1 showing a formation of the upper flange and the union of the lower part of the vessel; Figure 6 is a section of Figure 5, taken along line 6-6 showing the flattening of the corrugated material before the formation of Figure 5; Figure 7 is a section taken along line 7-7 of Figure 5 showing the corrugated material without flattening; Figure 8 is a detailed view of the corrugated material during the winding to join it to the bottom of the vessel, showing the sliding between the layers, which is allowed by the deformed corrugated layer which reduces the internal shear forces and the tearing of the outer layer; Figure 9 is a view of the sliding of the two different layers of corrugated material in a second embodiment of the invention in which it is possible to use slow hardening rubber to join the corrugated elements together; Figure 10 is a section through a cup-forming mandrel of a cup making machine showing a formation of the corrugated material around the mandrel by the wings of upward movement; Figure 11 is a section similar to Figure 3 showing a third embodiment with a stamped outer layer; Figure 12 is a Figure similar to Figure 3 showing a fourth embodiment with a pleated inner paper layer; Figure 13 is a Figure similar to Figure 4 showing the compression of the inner paper layer to allow the curvature of the sheet.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Now, with reference to Figure 1, a vessel 10 of the present invention has a straight wall 12 wound in a tube that forms a truncated cone of a cone (hereinafter frustoconical tube) attached at its lower edge 14 to a circular base (not shown in Figure 1) to contain a volume 16 to receive a drink. The straight wall 12 is composed of a corrugated board material having an inner paper wall 18 immediately adjacent to the volume that will contain the beverage 16, which is surrounded by a corrugated paper layer 20 having vertically extending corrugations 22. That is, the corrugated paper layer in turn is surrounded by an outer layer of paper 24 which interposes the corrugated paper layer 20 between itself and the inner layer of paper 18. An adhesive (not shown) connects the layer of paper. corrugated paper 20 to the inner layer of paper 18 and the outer layer of paper 24 according to methods well known in the art. The inner paper layer 18 is covered with a thin water resistant coating 26 to provide protection to the inner paper layer 18 of the hot liquid that may be contained within the volume 16. In the preferred embodiment, the coating 26 is a pulpable acrylic that allow the glass to be easily recycled. These coatings are available with the Spectra-Guard 763HS brand from Spectra-Kote company of Gettysburg, PA as described in US Patent 5,393,566; 5,429,294; and 5,531,863 which are incorporated herein by reference. It will be understood that a variety of moisture resistant materials including waxes and acrylics can be used to provide this protection. Now with reference to Figure 4, the straight wall 12, before being rolled into a vessel as shown in Figure 1, is cut from a sheet 28 of corrugated material in a sector of a ring so that by means of this it is can roll in a frusto-conical shape of Figure 1. The corrugation undulations are generally along a vertical axis 30 that extends along a line of the ring radius while the formation of the sheet 28 in the frusto-conical shape is along a circumferential direction 32 crossing the vertical axis 30. Now with reference to Figure 3 in a first embodiment, the outer layer of paper 24 of the corrugated sheet 28 is constructed of an extendable paper that will be lengthened under tension along the circumferential direction 32. This paper can be a pleated paper having multiple randomly formed wrinkles and folds that under tension-straightened allow the outer layer of paper 24 to extend com or is described. Otherwise, in a second embodiment (not shown), the outer layer of paper 24 can be a paper known as extensible kraft that provides elongation at the level of the paper fibers. Extendable kraft paper is commercially available with the extensible XKL brand from Thilmany Pulp and Paper Company of Kaukauna, Wisconsin. With reference to Figure 11, in a third embodiment, the outer layer of paper 24 can also be a stamped paper 25, wherein the stamping 25 can be flattened when the paper is put under tension allowing the paper to be stretched. Other extensible materials may also be used as will be apparent from the description for those skilled in the art. Referring now to Figure 4, when the sheet 28 is rolled as indicated by the arrows 34, in a frustoconical shape, the outer paper layer 24 can extend along the circumferential direction 32 to allow wrapping without tearing the outer layer of paper 24 or crushing of the corrugations of the corrugated paper layer 20. The extension of the outer layer of paper 24 is necessary due to the substantially greater thickness of the sheet 28 than a single sheet of paper normally used for the straight wall 12 of a glass. This increased thickness of the wall material displaces the outer layer of paper 24 to a greater radius than the outer layer of paper 18 requiring a significant increase in the circumferential length of the outer layer of paper 24. An extension of the outer layer of paper 24 2 to 15% is considered adequate for most sizes of normal containers with the necessary thickness of the corrugated material. Now, with reference to Figures 12 and 13, in a fourth embodiment, the inner layer 18 can be a pleated or printed paper. When the sheet 28 is rolled as indicated by the arrows 34 in a frustoconical shape, the inner paper layer 18 can be compressed along the circumferential direction 32 'to allow wrapping without tearing the outer layer of paper 24 or crushing the paper layers. undulations of the corrugated paper layer 20. In this embodiment, the compression of the inner layer of paper 18, instead of an extension of the outer layer of paper 24, accommodates the difference in the circumferences of the inner layer of paper 18 and the outer layer of paper 24 as the sheet 24 is rolled. Again, a compression of the inner paper layer 18 from 2 to 15% is considered suitable for most standard sizes of containers with the necessary thickness of the corrugated material. The ability of the paper layers to change the circumferential direction, extension or compression, as the vessel is rolled, in a necessary amount, will be called circumferential plasticity. It will be understood that the inner and outer paper layers can be constructed of paper having circumferential plasticity and, in this case, the amount of plasticity for each layer can be reduced than necessary only when a single layer having circumferential plasticity is used. Again with relation to Figure 2, before folding the sheet 28 and assembling it in a cup 10, the corrugations 22 (not shown in Figure 2) are squashed in a strip along the lower edge 14 and the upper edge 38 of the sheet 28. This flattening reduces the thickness of the corrugated paper layer 20 (as shown in Figure 6) before it is folded into a cup, and can be performed in a single operation during cutting with sheet die including anvils within the die blade to flatten the edges 14 and 38. In the same manner, the corrugations 22 are flattened in strips along the left and right edges 46 and 44 to allow sealing of these edges together as shown in FIG. will describe. Now in relation to Figure 10, the sheet 28 is bent around a frustoconical mandrel 40 by the forming wings 42 in a vessel making machine well known in the art. When the bending is completed, the left and right edges 44 and 46 of the sheet 28 are spliced together and welded together by a heat sealing or adhesive process as is well known in the art.

Now, and with respect to Figure 5, the flattened upper edge 38 of the straight wall 12 is rolled out to form a flange 48 according to conventional techniques for the construction of paper cups. Also, the lower edge 14 is wound around a flange extending downwardly on the periphery of the disk-shaped lower portion 51 to form a seal 49 against leakage of the contained beverage. The seal 49 is formed by heat sealing the bottom edge 14 to the base 51 or bonding it with adhesive. With reference to Figure 6, the flattening of the upper and lower edges 14 and 38 reduces the difference in radius between the inner layer of paper 18 and the outer layer of paper 24 in the fold of the flange 48 and the lower seal 49 reducing in this way the difference in the circumference of these two layers in the flange 48 and the seal 49 and the tendency of the outer layer of the paper 24 in the seal 49 and the inner layer of wall 18 in the flange 48 to tear. With respect to the seal 49, the extensible material of the outer paper layer 24 can also extend along the vertical axis 30 further reducing this tendency of the outer layer of paper 24 to tear with the elongation. Although the inventor does not wish to adhere to any specific theory, it is considered that both in cases of flange 48 and seal 49, the layer of flattened corrugated paper 20 facilitates a displacement, with winding, between layers 18 and 24. With regard to Figure 8, allowing a degree of displacement between the layers 18 and 24 in the seal 49, the elongation of the outer paper layer 24, necessary for the bending operation, is reduced. A similar effect occurs with respect to the opposite direction of the winding of the flange 48. With reference to Figure 7, because the collapse of the upper edge 38 and the lower edge 14 is limited to the region of the flange 48 and the seal 49, the thermal properties of most of the outer surface of the straight wall 12 conserve, in particular, the air spaces between the corrugated paper layer 20 and the layers 18 and 24. In another embodiment of the invention shown in FIG. General in Figure 9, this same principle of allowing a slide between the inner paper layer 18 and the outer paper layer 24 can be mentioned to allow the forming of the sheet 28 around the mandrel 40 with a reduced or minimal need for extension of the paper outer layer 24. In this embodiment, slow hardening adhesive 50 is used to assemble the sheet components 24 together. In particular, the opposite surfaces of the layer 18 and the layer 24 are coated with a slow hardening adhesive 50 and the sheet 28 is wound around the mandrel 40. At the moment that the wings 42 form the sheet 28 around the mandrel 40, the variations between the circumference, necessary for the inner layer of paper 18 and the outer layer of paper 24 to be accommodated by a relative sliding shown by the arrows 52 between the corrugated paper layer 20 and the inner layer of paper 18 and the layer of corrugated paper 20 and the outer layer of paper 24. A misalignment at the left and right edges 44 and 46 of the inner layer of paper 18 and the outer layer of paper 24, respectively, at a seam point, is relatively minor and it can be accommodated by flattening and heat sealing all the layers 18 and 24 of both edges 44 and 46 together in the seam line. Otherwise, the outer layer of paper 24 of the sheet may be larger than the inner layer of paper 18 and the corrugated paper layer 20. The slight loss in thermal resistance in this seam caused by the flattening of the space of air between the layers is moved by the seam comprising 6 layers of paper material. The adhesives 50 suitable for this purpose and the control of the hardening time of the adhesives are well known in the art. Normally moisture protection is required for the outer paper layer 24 when the vessel will be used for cold drinks as a result of the condensation that forms on the external surfaces. Nevertheless, in the glass of the present, the thermal insulating properties of the corrugated sheet greatly reduces this condensation. However, the outer surface of the outer paper layer 24 can also be coated with a water resistant material. The above description has been for a preferred embodiment of the present invention. It will happen that those who practice the technique will be able to make multiple modifications without departing from the spirit and scope of the invention. To inform the public of the various modalities that may fall within the scope of the invention, the following claims are made:

Claims (17)

1. A container that contains: a lower wall; and a straight curved wall along a circumferential direction joined at a lower edge to the lower wall, the straight wall includes an inner layer of paper an outer layer of paper and a central corrugated paper layer sandwiched between the inner layer of paper and the outer layer of paper and having undulations through the circumferential direction, having at least the inner paper layer or the outer layer circumferential plasticity paper that accommodates changes in the inner and outer circumference of the straight wall when the straight wall it is curved from a flat pre-assembled sheet.

2. The container of claim 1, wherein the outer layer of paper is pleated paper.

3. The container of claim 1, wherein the inner layer of paper is pleated paper.

4. The container of claim 1, wherein the outer layer of paper is extendable paper.

5. The container of claim 1, whereby the outer layer of paper is stamped paper.

6. The container of claim 1, whereby the inner layer of paper is stamped paper.

7. The container of claim 1, wherein the inner layer of paper is coated with a water-resistant, pulpable material.

8. The container of claim 1, wherein the outer layer of paper is a material that also has plasticity through the circumferential direction.

9. A method of manufacturing a paper container consisting of the steps of: (a) cutting a sheet of corrugated cardboard having an inner layer of paper, an outer layer of paper and a central layer of corrugated paper sandwiched between the inner layer of paper and the outer layer of paper and having corrugations along an axis, (b) the elongation of the outer layer of paper for winding the corrugated cardboard along an axis crossing the corrugations; and (c) attaching a bottom wall to a lower curved edge of the rolled corrugated cardboard. The method of claim 9, including the step of: flattening the lower curved edge of the corrugated board to flatten the corrugated paper layer; and wherein the step of attaching the bottom wall to the curved edge of the rolled corrugated cardboard includes the step of winding the curved edge around a projection on the bottom wall. The method of claim 9, including the step of: flattening an upper curved edge of the corrugated cardboard opposite the lower curved edge to flatten the corrugated paper layer; and includes the step of winding the curved edge into a flange 12. The method of claim 9 includes the step of: flattening a left and right edge of the corrugated board; and sealing the left and right edges together after step (b) 13. A method of manufacturing a paper container consisting of the steps of: (a) cutting a sheet of corrugated cardboard having an inner layer of paper, an outer layer of paper and a central layer of corrugated paper sandwiched between the inner layer of paper and the outer layer of paper and having corrugations along an axis, (b) the elongation of the outer layer of paper for winding the corrugated cardboard along an axis that crosses the corrugations; and (c) attaching a bottom wall to a lower curved edge of the rolled corrugated cardboard. The method of claim 13, including the step of: flattening the lower curved edge of the corrugated board to flatten the corrugated paper layer; and wherein the step of attaching the bottom wall to the curved edge of the rolled corrugated cardboard includes the step of winding the curved edge around a projection on the bottom wall. 15. The method of claim 13, including the step of: flattening the upper curved edge of the corrugated cardboard opposite the lower curved edge to flatten the corrugated paper layer; and includes the step of winding the curved edge in a flange 16. The method of claim 13 includes the step of: flattening a left and right edge of the corrugated cardboard; and sealing the left and right edges together after step (b) 17. A cardboard material that can be folded, consisting of: a first layer of paper; a second paper layer a corrugated paper layer at the center sandwiched between the first and second paper layers; wherein the first layer of paper is pleated paper.