Reusable tableware made of plastic and method for manufacturing the same.

Description

[0001] The invention relates to reusable tableware made of plastic and a method for manufacturing such reusable tableware.

[0002] Plastic tableware is generally well-known, for example, collapsible boxes, bowls, or plates made of polystyrene. However, such tableware is only suitable for single use. Polystyrene is relatively brittle and not very temperature-resistant, which makes cleaning in a dishwasher, for example, and therefore reuse, impossible.

[0003] From DE 44 06 039 C1, a reusable packaging made of particle foam is known. To produce it, a carrier material made of a thermoplastic or thermally deformable polymer film is provided and coated with an adhesive layer. Foam particles made of polymer material are then applied to the carrier material, with the adhesive layer forming a bond between the carrier material and the particle foam. The resulting composite of carrier material and particle coating is then placed in a foaming device, and a cavity of the molded body is filled with particles. Expanded polystyrene (EPS) is proposed as the particle foam. This is intended to produce a recyclable reusable packaging.

[0004] EP 3 838 971 A1 describes the manufacture of a plastic container from a three-layer sheet comprising a foamed core layer of a polypropylene composition and two non-foamed layers of a polypropylene and polyethylene composition on both sides. The multi-layered sheet is formed by co-extrusion of the foamed layer together with the two non-foamed outer layers. The article is thermoformed from the sheet.

[0005] US Patent 2016 / 0082692 A1 describes the manufacture of a multi-layered sheet in which non-expanded material containing polypropylene is co-extruded, extrusion-coated, or laminated onto a first layer of expanded foam material containing polypropylene. A thermoforming process for forming a container from the sheet material includes producing a blank for a bottom element and a blank for a sleeve, bending the sleeve, and producing a sleeve seam and a bottom seam to join the sleeve to the bottom.

[0006] US Patent 2003 / 0186039 A1 describes a multilayer sheet comprising a layer of foamed polypropylene and a non-foamed layer of a filler. Manufacturing methods include extrusion lamination, sandwich lamination, and a method in which at least one surface of a sheet made of a thermoplastic material and a foamed sheet is heated and laminated together. A container is formed from the sheet by heating and vacuum and / or pressure forming.

[0007] DE 203 04 809 U1 describes thermoformed composite materials consisting of an uncrosslinked polypropylene foam film with a cover layer made of a woven fabric, felt, velour, or nonwoven material, used as interior lining components in the footwell or trunk of motor vehicles. The cover layers are formed before and / or during bonding with the foam film in a thermoforming or deep-drawing process.

[0008] DE 101 58 253 A1 describes the production of a foamed polypropylene resin container for microwave heating and the production of a laminated sheet by laminating at least one side of a foamed polypropylene resin layer with a non-foamed layer comprising a polypropylene resin, and heating and shaping the laminated sheet. The shaping process for forming the foamed polypropylene resin container includes softening the sheet by heating and shaping it by a vacuum and / or pressure forming process.

[0009] EP 1 144 186 B1 describes a method for manufacturing a dimensionally stable packaging container from a multilayer structure with gas barrier properties. The packaging container is a folded container, a bottle, or a similar extrusion blow-molded container.

[0010] EP 2 160 290 B1 describes a multilayer foamed polymer article comprising a non-laminated multilayer thermoplastic sheet. This sheet has first and second discrete outer layers, between which a plurality of discrete inner foamed layers are arranged, the said layers being integral to one another. The multilayer foamed polymer article, in particular a cup or tray, is manufactured from a solid monolithic thermoplastic sheet. The manufacturing process comprises the absorption of an effective amount of plasticizing gas into the thermoplastic sheet, desorption of the gas, and heating of the thermoplastic sheet to produce a foamed thermoplastic sheet from which multilayer foamed polymer articles are manufactured by thermoforming.

[0011] EP 2 258 545 B1 describes an easy-to-open, non-thermoformed packaging made from a multilayer film. This film comprises a monoaxially stretched, sealable layer based on a foamed thermoplastic olefin polymer and a monoaxially stretched longitudinal carrier layer based on at least one thermoplastic polymer, and optionally a barrier layer. The multilayer film can be produced and processed as tubular film or as cast film. Packaging made from the multilayer film can be a bag or a wrap-around package.

[0012] Based on the prior art described above, the invention aims to provide reusable tableware that is particularly durable even after multiple reuses.

[0013] The problem is solved by a reusable tableware according to claim 1. Advantageous embodiments are the subject of the dependent claims, the description and the figures.

[0014] The inventive method for manufacturing reusable tableware comprises the following steps: Extruding a continuous web of polypropylene plastic foam to form a closed surface of the plastic foam using a foam extruder, subsequent lamination in liquid state of a polypropylene plastic layer directly onto the top and bottom of the web, forming the reusable tableware by deep drawing and subsequent die-cutting of the reusable tableware from the web provided on both sides with the laminated polypropylene plastic layer.

[0015] The reusable plastic tableware according to the invention comprises a base body made of an extruded plastic foam and at least one plastic layer laminated onto one side of the base body.

[0016] The inventive method for manufacturing the reusable tableware comprises the steps: extruding a continuous web of plastic foam using a foam extruder, laminating a plastic layer onto the top and / or bottom of the web, and deep drawing the reusable tableware article from the web provided with the laminated plastic layer.

[0017] The base body of the reusable tableware according to the invention consists of an extruded plastic foam, in particular extruded polypropylene (XPP). The extrusion process gives the plastic foam a closed surface. The extrusion of the continuous sheet of plastic foam thus takes place, in particular, with the formation of a closed surface. In contrast to the production of a base body from EPS, as in DE 4 406 039 C1 explained at the outset, the invention does not provide for EPS foam, i.e., not for plastic granules compressed under pressure and heat, but rather for a base body made of extruded plastic foam with a closed surface.

[0018] In contrast to known reusable items, the reusable tableware according to the invention is mechanically more robust due to its base body made of extruded plastic foam. The plastic polymer of the base body forms a honeycomb structure due to the manufacturing process, which, unlike expanded plastics made from a composite of spheres, is significantly more stable and durable. Thanks to the base body made of extruded plastic foam, the reusable tableware according to the invention is therefore particularly durable and can be frequently cleaned and filled with food products without becoming brittle. The extrusion process can be carried out, in particular, under a butane atmosphere.

[0019] According to the invention, a plastic layer is laminated onto at least one side of the base body. This side can be the top and / or bottom of the continuous sheet of plastic foam during the manufacturing process. The laminated plastic layer contributes to the further durability of the reusable tableware. The plastic layer protects the base body made of extruded plastic foam, at least on one side, from external influences, particularly from the product contained in the reusable tableware. In one embodiment, the base body can have the laminated plastic layer on a side intended for contact with a product, such as food, to be contained in the reusable tableware. The plastic layer is applied, in particular, in a liquid state.Thanks to the closed surface of the extruded plastic foam for the base body, the plastic layer laminated onto it adheres particularly well to the base body, especially without an additional adhesive layer.

[0020] The laminated plastic layer not only protects reusable tableware from food residue but also allows for easy cleaning without damage. In one embodiment, the base of the tableware is coated with this laminated plastic layer on both sides. This allows the reusable tableware to be cleaned from all sides and makes it dishwasher-safe. The plastic layer can be applied, for example, to the top and bottom of the continuous sheet of foam plastic, so that a reusable tableware item made from this sheet has the laminated plastic layer on both the inside and outside. All of this contributes to its reusability.

[0021] Depending on the design, reusable tableware can be a collapsible box, a plate, a bowl, or a cup. As mentioned, reusable tableware is specifically designed and intended for holding food. It can be liquid-tight, particularly due to the laminated plastic layer. Thus, the aforementioned reusable items are suitable for holding food and for reuse.

[0022] In one design, the plastic foam is a polypropylene foam; the base body can therefore be made of extruded polypropylene, XPP. XPP offers the advantages described earlier, particularly the mechanical and temperature resistance of the base body and thus of the reusable tableware. Therefore, a base body made of XPP contributes significantly to the multiple reuse of the reusable tableware. Compared to manufacturing methods other than extrusion, XPP has the advantage of forming a particularly dense, closed surface, and thus, in particular, the aforementioned durability. XPP also exhibits this advantage compared to other extruded plastic foams. For example, XPP forms the honeycomb structure already mentioned, with cell sizes that can vary considerably.In particular, compared to polystyrene, it offers the advantage of lower brittleness and therefore better reusability.

[0023] In one design, at least one plastic layer is a polypropylene layer. Therefore, a polypropylene layer can be laminated onto one or both sides of the continuous web. Polypropylene is particularly durable.

[0024] After a certain design process, the reusable tableware is deep-drawn from a flat material. This flat material is, in particular, a continuous sheet of plastic foam laminated on one or both sides. The reusable tableware can be formed from this sheet by deep drawing and, if necessary, subsequent die-cutting. This particularly simple and efficient manufacturing method is made possible by the extrusion process.

[0025] In one embodiment, the at least one plastic layer is applied directly to the base body. The plastic layer can therefore be laminated onto the base body on one or both sides in direct contact with it. Thanks to the extrusion of the base body from plastic foam according to the invention and the resulting closed surface, such direct lamination of the plastic layer is possible, as it adheres securely to the base body even without an additional adhesive layer. In particular, no adhesive layer is applied between the plastic layer and the base body. This manufacturing process is particularly simple and yet allows for a particularly durable reusable tableware. The reusable tableware can thus be composed of only two components: the base body made of extruded plastic foam and the plastic layer laminated to it on one or both sides.

[0026] According to one embodiment of the inventive process, extrusion and lamination are carried out inline using a single machine. This manufacturing process is particularly simple. Such inline lamination is possible due to the extrusion of a continuous web of plastic foam. A separate machine can be provided for thermoforming and, if necessary, die-cutting. For example, after extrusion and lamination, the resulting web of plastic foam with a plastic layer laminated on one or both sides can first be wound onto a roll and then transferred to another machine for further processing.

[0027] One embodiment of the invention is explained below with reference to figures. These show: Figure 1 shows a schematic view of the structure of the reusable tableware comprising a base body and plastic layers laminated to both sides, Figure 2 shows a reusable tableware according to the invention, and Figure 3 shows the cell structure of the extruded plastic foam of the reusable tableware.

[0028] Unless otherwise stated, the same reference symbols refer to the same objects.

[0029] In Figure 1The layered structure of a reusable plastic tableware according to the invention is shown, comprising a base body 12 made of an extruded plastic foam and plastic layers 14, 16 laminated to both sides of the base body 12. The base body preferably consists of polypropylene, i.e., it forms an extruded polypropylene foam, also known as XPP. The plastic layers 14, 16 preferably also consist of polypropylene. It is also possible, in principle, to have such a laminated plastic layer on only one of the two sides of the base body 12.

[0030] Figure 2 shows a reusable tableware 18 according to the invention with a [missing information] as just shown. Figure 1 explained layer structure. Regarding the reusable tableware item made of Figure 2This is a bowl for holding food. The reusable tableware item 18 is manufactured by first extruding a continuous sheet of polypropylene foam and, if necessary, butane gas using a foam extruder. Subsequently, preferably inline, a polypropylene layer is laminated onto the top and bottom of the sheet, i.e., applied in a liquid state. This creates an XPP sheet with the laminated polypropylene layer on both sides. The reusable tableware items are then formed from this sheet by thermoforming and die-cutting.

[0031] The XPP base body forms a Figure 3The visible honeycomb structure 20 is evident. Such a structure contributes to the stability, in particular the mechanical resistance and temperature resistance, of the base body and thus of the reusable tableware. This is a significant improvement over expanded plastic foams, especially EPS, in which plastic granules are compressed under pressure and heat. Thus, the base body according to the invention, made of XPP, has a closed surface, as also shown in Figure 3 This is easily recognizable. A base made of EPS cannot guarantee this. The improved material properties achieved thus make the reusable tableware particularly reusable and, in particular, easy to clean even at high temperatures.

[0032] The plastic layer, laminated to both sides of the base, protects the base, particularly from liquids such as food or cleaning fluids. This, especially with double-sided lamination, allows for cleaning, for example in a dishwasher, further enhancing reusability. Thanks to its smooth surface, the plastic layer adheres well to the base, often without the need for an additional adhesive layer.

Claims

1. A method for production of reusable dishware, comprising the following steps: • extruding a continuous sheet of polypropylene plastic foam under formation of a closed surface of the plastic foam by means of a foam extruder, • subsequently laminating a polypropylene plastic layer in a liquid state directly onto the upper side and the lower side of the sheet, • forming the reusable dishware article by deep drawing and subsequently punching out the reusable dishware article from the sheet provided on both sides with the laminated polypropylene plastic layer.

2. Method according to claim 1, wherein the extruding and laminating are carried out in-line with a single plant.

3. Method according to any one of the preceding claims, wherein the reusable dishware is a hinged box, a plate, a bowl or a cup.