Three-Dimensional Molded Body and Method of Manufacturing a Three-Dimensional Molded Body of Fiber-Containing Material

The present application claims priority under 35 U.S.C. § 119 to German Patent Application No. DE 10 2024 117 149.9, filed Jun. 18, 2024, the disclosure of which is incorporated by reference herein in its entirety.

A three-dimensional molded body made of fiber-containing material and a method for producing a three-dimensional molded body made of fiber-containing material are described.

Fiber-containing materials are increasingly used, for example, to produce packaging for food (e.g., trays, capsules, boxes, etc.) and consumer goods (e.g., electronic devices, etc.) as well as beverage containers. The fiber-containing materials can have natural fibers, which are obtained, for example, from renewable raw materials or waste paper. The natural fibers can be mixed in a so-called pulp with water and, optionally, further additives, such as starch, and then formed. Additives can also have an effect on color, barrier properties, and mechanical properties. A pulp can have a proportion of natural fibers of, for example, 0.1 to 10 wt. %. The proportion of natural fibers can vary according to the method used for the production of packaging, etc., and the product properties of the product to be produced. Fibers, such as natural fibers, can also be introduced into molding tools in a dry state and processed or formed therein. Alternatively, such fibers can be processed into starting materials for subsequent shaping. Starting materials for further processing can, for example, be so-called webs or sheets, such as airlaid, fluff pulp, paper, etc., as well as multi-layer arrangements made of the above materials, made of a fiber-containing material, which are then formed in a molding tool.

Production processes for products or molded bodies made of a fiber-containing material involve a wet process, where the molded bodies are pressed from fibers that are drawn out of an aqueous suspension and pressed to form finished molded bodies in one or more process steps under heat and pressure. Another method relates to a dry process, where a relatively loose fiber composite (e.g., airlaid) with a low moisture content is pressed under high pressure and heat to form finished molded bodies.

When processing such molded bodies, they are stacked after forming in a subsequent processing step, e.g., for transport or the like. For example, it is known to stack thermoformed cups made of a plastic after forming in order to then transport them, where in the stacked state the space required for transporting a large number of cups is considerably reduced. The cups can then be separated from each other without much difficulty, with the cups being removed piece by piece from a stack from the inside or outside. The plastic material of the cups allows the side walls of the cups to slide easily against each other. When stacking cups or capsules made of a fiber-containing material, for example, there is also a desire to stack them after production in order to have a relatively small space requirement during transport or storage. However, stacking proves to be difficult and sometimes extremely disadvantageous, especially with cups or the like made of a fiber-containing material, since, due to the properties of the fiber-containing material, the cups adhere strongly to one another at the contact points, and the friction between the fibers or the fiber-containing material is increased. As a result, a great deal of force is required to remove cups or the like from a stack, which may also result in damage to the cups. Since the cups are deliberately designed to be as identical as possible, they are in contact with each other over a relatively large area.

The known embodiments of molded parts made of a fiber-containing material therefore have the disadvantage that they cannot be stacked or can only be stacked with great difficulty and subsequently unstacked without a great deal of force being required and/or the molded parts being damaged during unstacking.

Thus, it is an object to provide a solution that eliminates the disadvantages of the prior art, where in particular molded parts made of a fiber-containing material can be stacked and unstacked easily and without damage.

The aforementioned object is achieved by a three-dimensional molded body of a fiber-containing material, having a circumferential side wall, which surrounds an interior of the molded body, and an edge region, where a stacking shoulder is formed in a transition from the side wall to the edge region, and the edge region has an undercut.

Such a molded body offers a solution for easy stacking and unstacking when the molded body is made of a fiber-containing material, by reducing the contact surface of stacked molded parts, such as cups, capsules, etc.

The design of the stacking shoulder and the undercut enable stacking of molded parts of fiber-containing material with a reduced contact surface between nested or stacked molded parts, where the molded parts can rest on each other in the region of the stacking shoulder. The undercut ensures that the edge region of an outer molded part is not in full contact with a corresponding edge region of an inner molded part in a stacked state, so that the contact areas are thereby significantly reduced. As a result, the adhesive and frictional effect due to the fiber-containing material also decreases, and the stacking and unstacking of molded parts of fiber-containing material is thereby greatly improved.

When forming edges in an edge region, these can, for example, have a ring-like portion that forms a stacking shoulder, particularly in the transition from the side wall to the ring-like portion. The stacking shoulder can determine how far molded parts can be stacked into each other. Thus, the stacking shoulder can serve as a limiting element. If an undercut is provided in the region of the stacking shoulder, preferably above the stacking shoulder starting from the transition between the ring-like portion and the side wall in the ring-like portion, the contact surface in the region of the ring-like portion is reduced by the undercut, so that a stacking shoulder can be provided in a molded part without the previous disadvantages, as in the prior art. In particular, this makes it possible to provide a limiting element for stacking, the contact surfaces of which are limited to a minimum, and where the function of the limiting element is restricted to the main component.

The cross-section of at least the interior of the molded part can be round (circular, elliptical, oval) or polygonal (triangular, square, pentagonal, etc.).

In further embodiments, the stacking shoulder can merge into the undercut, where the undercut directly adjoins the stacking shoulder.

In further embodiments, a cross-section of the undercut can have a decreasing cross-section proceeding from the stacking shoulder in the direction of a region remote from the undercut, where the largest cross-section or, in the case of round molded parts, the largest diameter, runs in the region of the stacking shoulder.

In further embodiments, the side wall can have a degressive profile, at least sectionally, proceeding from the edge region to a base region, where a cross-section of the side wall in the base region is smaller than a cross-section in the edge region. The degressive profile of the sidewall achieves an additional reduction in the contact surface. The resulting change in cross-section allows molded parts, such as cups or capsules, to be stacked relatively deeply into one another, where, despite the large overlap of adjacent side walls of at least two molded parts, the contact surface is considerably reduced compared to known embodiments. The overlap is defined by the region in which the side walls of stacked molded parts face each other. The extent of the degressive profile defines how large the contact surfaces are between the side walls of stacked molded parts. The degressive profile of the side wall therefore enables the stacking of fiber-containing molded parts, where the influence of the fibers and the resulting friction or adhesion of adjacent side walls is reduced.

In addition, molded parts can have an edge that extends orthogonally or in a protruding arrangement from the molded body in the edge region, so that, over the edge, slipping too far in or stacking too deep in addition to the stacking shoulder is prevented. This allows the contact surface or the maximum contact region between side walls of stacked molded parts to be limited or defined.

A further advantage of such a degressive profile is the easy unstacking compared to purely conical molded bodies, because the contact region or the contact surface of two stacked bodies is located near the edge region. This also means that jamming is less likely to occur, as is the case, for example, near the base region of purely conically tapered molded parts, because, in the region with the larger cross-section, the molded part can be compressed to a greater extent or more easily and is therefore more likely to give in to friction or adhesion effects.

A further advantage of a degressive profile can also arise when using three-dimensional molded bodies made of a fiber-containing material, if these have to be inserted into corresponding receptacles after filling during use and then removed again. For example, a degressive profile can make it easier to remove or eject coffee capsules made of a fiber-containing material from a coffee machine receptacle, since the force required for ejection can be kept substantially constant.

The degressive profile can be stronger or weaker along the side wall or in portions of the side wall.

In further embodiments, the degressive profile can extend from the base region to the edge region, so that the side wall has a degressive profile over the entire height of the interior, which further facilitates stacking and unstacking.

In further embodiments, the degressive profile along the side wall can be divided into sections of equal length per definable distance, where the gradient of at least two consecutive sections is different from one another.

In still further embodiments, the cross-section or a diameter of the interior space along the side wall from the edge region towards the base region can decrease by 0.4-0.9 times with increasing distance from the edge region per definable distance, where in this region sufficient stability of the molded body prevails with a minimum contact surface when the molded bodies are stacked one inside the other.

In further embodiments, the definable distance can be defined parallel to the height of the interior or along the surface of the side wall.

Depending upon the definition of the distance over the height of the interior or along the side wall, the cross-section or diameter can decrease per section by a definable amount, which, for example, lies in the range specified above.

In further embodiments, the side wall can have a straight and a curved profile in portions, where, in portions of the side wall that follow a contact region of stacked molded parts, the profile can again be straight, provided that this does not create an additional contact point.

In further embodiments the degressive profile is shaped in such a way that, when three-dimensional molded bodies are stacked, there is only line contact between at least two stacked three-dimensional molded bodies in the region of adjacent side walls of the at least two three-dimensional molded bodies. The line contact is defined by an outer circumferential line that runs essentially parallel to a base surface or the base area of the molded bodies. In such designs, the at least two molded bodies can only be in contact with each other between their side walls via an annular contact area. Thereby, the contact area is reduced to a minimum, so that unstacking is very easy.

The aforementioned object is also achieved by a method for producing a three-dimensional molded body according to one of the above embodiments, involving

Further features, embodiments, and advantages result from the following illustration of exemplary embodiments with reference to the figures.

Various embodiments of the technical teaching described herein are shown below with reference to the figures. Identical reference signs are used in the figure description for identical components, parts and processes. Components, parts, and processes that are not essential to the technical teachings disclosed herein or that are obvious to a person skilled in the art are not explicitly reproduced. Features specified in the singular also include the plural unless explicitly stated otherwise. This applies in particular to statements such as “a” or “one.”

depicts a schematic sectional representation of a molded part. The molded partcan be designed, for example, as a bowl, cup, capsule, etc., and includes or consists essentially of a fiber-containing material or includes fiber-containing material as its predominant component. The fiber-containing material may, for example, contain predominantly natural fibers. The fiber-containing material may contain additives that influence the properties of the molded partwith regard to barrier properties, mechanical properties (strength, etc.), color, printability, etc.

The molded partdepicted inhas a base regionthat can serve as a supporting surface for the molded part. A circumferential side wallextends from the base region. The side wallis adjoined by an edge regionwith a ringand an edge. In a transitionfrom the side wallto the edge region, the molded parthas a stacking shoulder. The molded parthas a round cross-section and can be rotationally symmetrical. In further embodiments, the cross-section can be polygonal.

For easier stacking and unstacking of such molded parts, the molded partdepicted inhas an undercutin the edge region. The undercutis located in a ringthat adjoins the stacking shoulder. The stacking shoulderis formed in the transitionbetween the side walland the ring(see, for example,). In the region of the stacking shoulder, the molded partcan have a significant change in cross-section or diameter compared to the side wall.depicts in particular a schematically strong change in diameter for illustration. The stacking shouldercreates a contact surfaceon the outer side of the molded partfor a corresponding region or a contact surfaceof another molded part. The design of the stacking shoulderand the corresponding region is depicted in particular in, where a first molded partin a contact regionvia its contact surfaceon the outer side of the stacking shoulderis in contact with a contact surfaceon the inner side of a second molded partin the transition from the ringto the edge. A further molded partinserted into the molded partrests with its stacking shoulderat the transition from the ringto the edge, as depicted, for example, in. By forming the radii on the inner side and outer side in the region of the stacking shoulderor the corresponding contact surfacein the transition from the edgeto the ringdifferently from one another, the support surface or the contact region() can be further reduced, where the radius on the inner side can be larger than the radius on the outer side of the molded part.

The undercutreduces a contact surface(see) between two stacked molded partsthat are held by the stacking shoulder, with respect to the stacking depth, in the edge region. The reduction of the contact surfacesin the stacked state accordingly also reduces the effect of the fiber-containing material of the molded partsamong each other, so that adhesion or fiber-related friction is reduced, which significantly simplifies stacking and unstacking and prevents damage.

In addition, the molded partdepicted inhas a degressive profile in the side wall, so that the cross-section or diameter decreases increasingly with increasing distance from the edge regionin the direction of the base. This ensures that, in the stacked state of molded parts, a contact region(see) between two side wallscan be reduced to a required minimum. This reduces the areal proportion of the side walls, which lie against each other in the stacked state and are in direct contact with each other. Until now, the contact region of, for example, prior-art cups made of a fiber-containing material was relatively large and could extend over almost the entire side wall surface. This meant that a relatively large amount of force had to be applied when stacking because the side walls that came into contact with the material exhibited strong friction or adhesion due to the fiber-containing material. Likewise, with the known embodiment of molded parts, a great deal of force is required to unstack molded parts that are stacked inside each other. Furthermore, in the prior art, the forces required for stacking and unstacking depend upon the overlap of the side surfacesor the stacking depth, and must be changed during stacking and unstacking in order to reduce damage to molded parts. Overall, with the known embodiment of molded parts, it is therefore only possible to stack and unstack molded parts with great effort, where damage is always possible due to the adhesion or friction of the side walls due to the fiber-containing material.

The design of the stacking shoulderand the undercutas well as, in other embodiments, the degressive profile of the cross-section or diameter of the molded partin the embodiments depicted allow a reduction of the contact surfaces, thereby reducing the effect of adhesion between molded parts.

The formation of the edgein the edge regioncan, as depicted for example in, be orthogonal to a vertical axis H, or also curved, groove-like, etc.

depicts a schematic representation of stacked molded partsin a sectional view. The molded partssubstantially correspond to the embodiment previously depicted with reference to. The contact regionbetween the side wallsof the molded partsand the contact regionbetween the edge regionsor stacking shouldersof the molded partsare reduced compared to molded parts from the prior art, so that the disadvantages due to the fiber-containing material and its properties are also reduced.

depicts a further schematic representation of a molded partand an exemplary embodiment of a degressive profile. Along the vertical axis H of the molded part, portions Ato Aor A′to A′are defined. The portions Ato Adivide the side wallinto equal-sized portions running parallel to the vertical axis H. With increasing distance from the edge region, in the portions Ato A, the curvature in the portions A′to A′increases so that the deflection increases orthogonally to the vertical axis H. Accordingly, the length of the portions A′to A′increases with increasing distance from the edge regiontowards the base.

The degressive profile can describe a branch of a parabola, where in further embodiments the branch of a parabola can be rotated around a pivot point D. The pivot point can in particular be located in a portion of the side wallthat is closer to the edge regionthan to the base. An exemplary position for a pivot point D is depicted in.

depicts a schematic sectional representation of a further molded part. The molded partdiffers from the other embodiments depicted in terms of shape, but also has a degressive side wall profile for a side walland an undercutthat extends from a stacking shoulderin a ringof an edge region, as depicted in detail in.

The degressive profile of the side wallis depicted by line g, which runs at the lower end of the side wallat the level of the baseand at a distance from the side wall. At the level of the base, line g forms an angle α with the outer side of the molded partopposite the side wallthat can be in the range of 0.5° to 25°. Preferably the angle α is approximately between 1° and 15°.

depicts an enlarged view of a detail of the molded partfromin the edge region. In particular, an embodiment of the stacking shoulderand the ringis depicted. The undercutcan, as depicted in, have a negative profile with respect to a molding and demolding direction that runs in the direction of the vertical axis H. In this case, the undercutin the region of an inner edge areahas a profile depicted by line h, which, starting from a starting point P of the undercut, is inclined by an angle β relative to line p running parallel to the vertical axis H. The angle β can be in the range of 0.5° to 10°. Preferably the angle β is approximately between 0.5° and 2°.

The undercutensures that the contact surfacein the edge regionis reduced compared to molded parts from the prior art. In, a design of the contact regionsis depicted, which includes the contact surfaceon the outer side of the stacking shoulderand a contact surfacein the transition between the ringand the edge, where a contact surfaceof a further molded partcan come into contact with the contact surface, and a contact surfaceof a still further molded partcan come into contact with the contact surface, and where the contact surfaces are thus reduced.

depicts a schematic representation of further stacked molded partsin a sectional view, where the contact of two molded partsis depicted by the special design of the stacking shoulder.depicts an enlarged view of the contact regionbetween a contact surfaceon the outer side of the stacking shoulderof a molded partand a contact surfacein the transition between a ringand an edgeof the molded partsof. The undercutenlarges, as depicted schematically, a region between an edge areaand the opposite outer side of the opposite side wall.

depicts a schematic representation of further stacked molded partsin a sectional view, where, in addition to the special design of the stacking shoulder, a degressive profile of the side wallsis also depicted, whereby the contact surface between the side wallsof molded partsstacked one inside the other is considerably reduced, and these can therefore also be easily unstacked.depicts an enlarged view of the contact regionbetween a contact surfaceon the outer side of the stacking shoulderof a molded partand a contact surfacein the transition between a ringand an edgeof the molded partsof, anddepicts an enlarged view of the contact regionbetween the side wallsof the molded partsof.

The formation of molded partsdescribed herein can take place in a forming tool for pressing fiber-containing material, which has a geometry and molding surfaces adapted to the geometry of the molded partto be produced. The described embodiment of molded parts, despite the optimized embodiment with regard to small contact surfaces,in stacked molded parts, does not require a complex tool design, where, for example, undercutscan be made without slides or other separate, movable mold elements in a forming tool.

The production of three-dimensional molded bodiescan be carried out in several steps, where a fiber-containing material can be provided first. The fiber-containing material can be provided, for example, as pulp or dry fiber material.

The fiber-containing material is then introduced into a mold of a forming tool, and then the forming tool is closed by relative displacement of the mold and a corresponding mold element. The fiber-containing material is then pressed into three-dimensional molded bodieswith the formation of a stacking shoulderin a transitionfrom a side wallto an edge regionand with the formation of an undercutthat extends from the stacking shoulderto an open region of the molded part. In addition, a degressive profile can simultaneously be created at least sectionally in a side wallof the molded part.

Since the undercutsgenerally have only a small deflection, the molded partscan be elastically deformed for a short time after pressing, similar to the demolding of plastic. The smaller the extent of undercuts, the lower the load on the molded partor the pressed fiber-containing material.

In further embodiments, the formation of undercutsin edge regionscan take place in a subsequent processing step after the forming or pressing in the forming tool, where, due to differences in humidity after pressing, the fiber-containing material can contract by drying, so that moist regions in the edge region, in particular in the ring, contract to form an undercutor make the undercutmore pronounced. An advantage of such downstream deformation steps is that only small or no undercutsneed to be formed during pressing, which facilitates the ejection or removal of formed molded partsfrom forming tools, since only small or no deformation of the undercutsoccurs during demolding.