THREE-DIMENSIONAL MOLDED BODY AND METHOD OF MANUFACTURING A THREE-DIMENSIONAL MOLDED BODY OF FIBER-CONTAINING MATERIAL

Description

PRIORITY CLAIM

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.

TECHNICAL FIELD

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.

BACKGROUND

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.

SUMMARY

Object

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.

Solution

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

• • providing a fiber-containing material,
  • introducing the fiber-containing material into a mold of a forming tool,
  • closing the forming tool by relative displacement of the mold and a corresponding mold element, and
  • pressing the fiber-containing material into a three-dimensional molded body with the formation of a stacking shoulder in a transition from a side wall to an edge region and with the formation of an undercut that extends from the stacking shoulder to an open region of the molded part.

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

BRIEF DESCRIPTION OF THE FIGURES

In the figures:

FIG. 1 depicts a schematic sectional representation of a molded part;

FIG. 2 depicts a schematic sectional representation of stacked molded parts;

FIG. 3 depicts a further schematic representation of a molded part;

FIG. 4 depicts a schematic sectional representation of a further molded part;

FIG. 5 depicts an enlarged view of a detail of the molded part from FIG. 4;

FIG. 6 depicts a schematic sectional representation of further stacked molded parts;

FIG. 7 depicts an enlarged view of the contact region in the stacking shoulder of the molded parts from FIG. 6;

FIG. 8 depicts a schematic representation of further stacked molded parts in a sectional view;

FIG. 9 depicts an enlarged view of the contact region in the stacking shoulder of the molded parts from FIG. 8; and

FIG. 10 depicts an enlarged view of the contact region between the side walls of the molded parts from FIG. 8.

DETAILED DESCRIPTION

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.”

FIG. 1 depicts a schematic sectional representation of a molded part 10. The molded part 10 can 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 part 10 with regard to barrier properties, mechanical properties (strength, etc.), color, printability, etc.

The molded part 10 depicted in FIG. 1 has a base region 12 that can serve as a supporting surface for the molded part 10. A circumferential side wall 14 extends from the base region 12. The side wall 14 is adjoined by an edge region 16 with a ring 15 and an edge 17. In a transition 24 from the side wall 14 to the edge region 16, the molded part 10 has a stacking shoulder 30. The molded part 10 has 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 10, the molded part 10 depicted in FIG. 1 has an undercut 18 in the edge region 16. The undercut 18 is located in a ring 15 that adjoins the stacking shoulder 30. The stacking shoulder 30 is formed in the transition 24 between the side wall 14 and the ring 15 (see, for example, FIG. 5). In the region of the stacking shoulder 30, the molded part 10 can have a significant change in cross-section or diameter compared to the side wall 14. FIG. 1 depicts in particular a schematically strong change in diameter for illustration. The stacking shoulder 30 creates a contact surface 32 on the outer side of the molded part 10 for a corresponding region or a contact surface 34 of another molded part 10. The design of the stacking shoulder 30 and the corresponding region is depicted in particular in FIGS. 5, 6, 7, and 9, where a first molded part 10 in a contact region 22 via its contact surface 32 on the outer side of the stacking shoulder 30 is in contact with a contact surface 34 on the inner side of a second molded part 10 in the transition from the ring 15 to the edge 17. A further molded part 10 inserted into the molded part 10 rests with its stacking shoulder 30 at the transition from the ring 15 to the edge 17, as depicted, for example, in FIG. 2. By forming the radii on the inner side and outer side in the region of the stacking shoulder 30 or the corresponding contact surface 34 in the transition from the edge 17 to the ring 15 differently from one another, the support surface or the contact region 22 (FIG. 2) 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 10.

The undercut 18 reduces a contact surface 22 (see FIG. 2) between two stacked molded parts 10 that are held by the stacking shoulder 30, with respect to the stacking depth, in the edge region 16. The reduction of the contact surfaces 22 in the stacked state accordingly also reduces the effect of the fiber-containing material of the molded parts 10 among each other, so that adhesion or fiber-related friction is reduced, which significantly simplifies stacking and unstacking and prevents damage.

In addition, the molded part 10 depicted in FIG. 1 has a degressive profile in the side wall 14, so that the cross-section or diameter decreases increasingly with increasing distance from the edge region 16 in the direction of the base 12. This ensures that, in the stacked state of molded parts 10, a contact region 20 (see FIG. 2) between two side walls 14 can be reduced to a required minimum. This reduces the areal proportion of the side walls 14, 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 surfaces 14 or 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 shoulder 30 and the undercut 18 as well as, in other embodiments, the degressive profile of the cross-section or diameter of the molded part 10 in the embodiments depicted allow a reduction of the contact surfaces, thereby reducing the effect of adhesion between molded parts 10.

The formation of the edge 17 in the edge region 16 can, as depicted for example in FIG. 1, be orthogonal to a vertical axis H, or also curved, groove-like, etc.

FIG. 2 depicts a schematic representation of stacked molded parts 10 in a sectional view. The molded parts 10 substantially correspond to the embodiment previously depicted with reference to FIG. 1. The contact region 20 between the side walls 14 of the molded parts 10 and the contact region 22 between the edge regions 16 or stacking shoulders 30 of the molded parts 10 are 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.

FIG. 3 depicts a further schematic representation of a molded part 10 and an exemplary embodiment of a degressive profile. Along the vertical axis H of the molded part 10, portions A₁ to A₅ or A′₁ to A′₅ are defined. The portions A₁ to A₅ divide the side wall 14 into equal-sized portions running parallel to the vertical axis H. With increasing distance from the edge region, in the portions A₁ to A₅, the curvature in the portions A′₁ to A′₅ increases so that the deflection increases orthogonally to the vertical axis H. Accordingly, the length of the portions A′₁ to A′₅ increases with increasing distance from the edge region 16 towards the base 12.

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 wall 14 that is closer to the edge region 16 than to the base 12. An exemplary position for a pivot point D is depicted in FIG. 3.

FIG. 4 depicts a schematic sectional representation of a further molded part 10. The molded part 10 differs from the other embodiments depicted in terms of shape, but also has a degressive side wall profile for a side wall 14 and an undercut 18 that extends from a stacking shoulder 30 in a ring 15 of an edge region 16, as depicted in detail in FIG. 5.

The degressive profile of the side wall 14 is depicted by line g, which runs at the lower end of the side wall 14 at the level of the base 12 and at a distance from the side wall 14. At the level of the base 12, line g forms an angle α with the outer side of the molded part 10 opposite the side wall 14 that can be in the range of 0.5° to 25°. Preferably the angle α is approximately between 1° and 15°.

FIG. 5 depicts an enlarged view of a detail of the molded part 10 from FIG. 4 in the edge region 16. In particular, an embodiment of the stacking shoulder 30 and the ring 15 is depicted. The undercut 18 can, as depicted in FIG. 5, 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 undercut 18 in the region of an inner edge area 19 has a profile depicted by line h, which, starting from a starting point P of the undercut 18, 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 undercut 18 ensures that the contact surface 22 in the edge region 16 is reduced compared to molded parts from the prior art. In FIG. 5, a design of the contact regions 22 is depicted, which includes the contact surface 32 on the outer side of the stacking shoulder 30 and a contact surface 34 in the transition between the ring 15 and the edge 17, where a contact surface 34 of a further molded part 10 can come into contact with the contact surface 32, and a contact surface 32 of a still further molded part 10 can come into contact with the contact surface 34, and where the contact surfaces are thus reduced.

FIG. 6 depicts a schematic representation of further stacked molded parts 10 in a sectional view, where the contact of two molded parts 10 is depicted by the special design of the stacking shoulder 30. FIG. 7 depicts an enlarged view of the contact region 22 between a contact surface 32 on the outer side of the stacking shoulder 30 of a molded part 10 and a contact surface 34 in the transition between a ring 15 and an edge 17 of the molded parts 10 of FIG. 6. The undercut 18 enlarges, as depicted schematically, a region between an edge area 19 and the opposite outer side of the opposite side wall 14.

FIG. 8 depicts a schematic representation of further stacked molded parts 10 in a sectional view, where, in addition to the special design of the stacking shoulder 30, a degressive profile of the side walls 14 is also depicted, whereby the contact surface between the side walls 14 of molded parts 10 stacked one inside the other is considerably reduced, and these can therefore also be easily unstacked. FIG. 9 depicts an enlarged view of the contact region 22 between a contact surface 32 on the outer side of the stacking shoulder 30 of a molded part 10 and a contact surface 34 in the transition between a ring 15 and an edge 17 of the molded parts 10 of FIG. 8, and FIG. 10 depicts an enlarged view of the contact region 20 between the side walls 14 of the molded parts 10 of FIG. 8.

The formation of molded parts 10 described 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 part 10 to be produced. The described embodiment of molded parts 10, despite the optimized embodiment with regard to small contact surfaces 20, 22 in stacked molded parts 10, does not require a complex tool design, where, for example, undercuts 18 can be made without slides or other separate, movable mold elements in a forming tool.

The production of three-dimensional molded bodies 10 can 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 bodies 10 with the formation of a stacking shoulder 30 in a transition 24 from a side wall 14 to an edge region 16 and with the formation of an undercut 18 that extends from the stacking shoulder 30 to an open region of the molded part 10. In addition, a degressive profile can simultaneously be created at least sectionally in a side wall 14 of the molded part 10.

Since the undercuts 18 generally have only a small deflection, the molded parts 10 can be elastically deformed for a short time after pressing, similar to the demolding of plastic. The smaller the extent of undercuts 18, the lower the load on the molded part 10 or the pressed fiber-containing material.

In further embodiments, the formation of undercuts 18 in edge regions 16 can 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 15, contract to form an undercut 18 or make the undercut 18 more pronounced. An advantage of such downstream deformation steps is that only small or no undercuts 18 need to be formed during pressing, which facilitates the ejection or removal of formed molded parts 10 from forming tools, since only small or no deformation of the undercuts 18 occurs during demolding.

The formation of molded parts 10 can vary depending upon the desired form. Essential for the embodiment disclosed herein is the provision of contact surfaces 20, 22 with reduced area in stacked molded parts 10.

The molded parts 10 described herein include or consist essentially of a fiber-containing material and can be produced, for example, in a so-called wet process, where preforms made of a fiber-containing material can first be provided that are then pressed under the action of heat. The preforms can be prepared in such a way that fibers are suctioned out of an aqueous solution (pulp), and three-dimensional preforms are formed that substantially already have the shape of the products to be manufactured. In addition, additives such as starch, chemical supplements, wax, etc., can be added to a pulp to influence the properties of the products to be manufactured (e.g., barrier properties) and the processability. The fibers can, for example, be natural fibers, such as cellulose fibers, or fibers from a fiber-containing original material (for example, waste paper). Since a fiber-containing pulp with natural fibers can be used as the starting material for the molded parts 10, after being used, the molded parts 10 produced can themselves once again be used as a starting material for producing molded bodies 10 or other products, or they can be composted, because they can usually be completely decomposed and do not contain any dangerous substances that are harmful to the environment.

In other embodiments, the preforms can be subjected to a pre-pressing step. The preforms are then pressed into three-dimensional molded parts 10 in a hot-pressing device under pressure and the action of heat.

Furthermore, the molded parts 10 can be (re)formed from a loose cellulose web (airlaid) or a paper.

In further embodiments, the molded parts 10 can be laminated or treated in other ways after their production, in order to achieve certain properties.

LIST OF REFERENCE SIGNS

• • 10 Molded part
  • 12 Bottom
  • 14 Side wall
  • 15 Ring
  • 16 Edge region
  • 17 Edge
  • 18 Undercut
  • 19 Edge area
  • 20 Contact region
  • 22 Contact region
  • 24 Transition
  • 30 Stacking shoulder
  • 32 Contact surface
  • 34 Contact surface
  • α Angle
  • β Angle
  • g line
  • h line
  • p line
  • D Pivot point
  • H Vertical axis
  • P Starting point