Method, casting mold, and production device

Abstract

The invention relates to a method and a casting mold for producing a fiber-based blank made of pulp (40). The method has the steps of • providing a casting mold, • filling the casting mold with a process liquid such that a liquid reservoir (31) is formed in the casting mold, and • applying pulp (40) onto the liquid reservoir (31) in the casting mold.

Description

[0001] Process, mold and manufacturing device

[0002] The present invention relates to a method for producing a fiber-based blank from pulp, in particular a container or a fiber-based closure element for a container, a casting mold for producing a fiber-based blank from pulp and a manufacturing device comprising a casting mold according to the preamble of the independent claims.

[0003] A fiber-based container was proposed in WO 2012 / 139590 A1. To manufacture this container, so-called pulp is injected into an upside-down mold and pressed against a corresponding wall using a flexible balloon in this mold, thereby compressing it. The pulp is compressed and heated to a temperature of approximately 180 °C to dry the container.

[0004] Pulp is a mixture of fibers and water, especially natural fibers such as hemp fibers, cellulose fibers, or flax fibers, or a mixture thereof. The pulp may contain additives that, for example, improve the hardening of the compressed pulp, influence its subsequent appearance, or generally alter the properties of the pulp or the subsequent container.

[0005] Since the pulp consists of different components whose properties can vary, the injection process is also very difficult to control. In particular, the type and amount of pulp deposited within the mold is largely left to chance. This is reflected in the finished container's different properties, for example, different wall thicknesses and thus different strengths or different surfaces.

[0006] The object of the invention is to remedy at least one or more disadvantages of the prior art. In particular, a method and a mold are to be provided that make it possible to monitor and preferably control the deposition of the pulp.

[0007] This problem is solved by the methods and devices defined in the independent patent claims. Further embodiments emerge from the dependent patent claims.

[0008] A method according to the invention for producing a fiber-based blank from pulp comprises the steps:

[0009] - Providing a casting mold,

[0010] - Filling the mold with a process liquid, especially water, so that a liquid reserve is formed in the mold,

[0011] - Applying pulp to the liquid supply in the mold.

[0012] Filling the mold with a process fluid makes it possible to create specific process conditions within the mold. The fluid reservoir provides a stationary column that is essentially free of turbulence and / or eddies.

[0013] By applying pulp to this liquid supply, two media with comparable properties are brought into contact. For example, if water is used as the process liquid, the liquid supply is also made of water. The pulp is also essentially a water-based mixture. Therefore, when the pulp is applied to the liquid supply, the two media do not mix. The liquid supply is essentially filled by the pulp.

[0014] The liquid supply therefore provides a standing water column which is merely extended by the application of pulp to this water column. A casting mold for producing a fiber-based blank is typically permeable to liquid and has two mold halves that can be separated from one another. These two mold halves provide a cavity into which the pulp is introduced. In a simple form, the casting mold can, for example, be made from a metal grid which has an outer boundary which is impermeable to liquid so that a liquid supply can be provided within this casting mold. In a simple form, the outer boundary can, for example, be provided by a container, which container can be flooded.

[0015] The cavity essentially corresponds to a negative impression of the blank to be produced and, like the blank, has a mouth opening. The pulp is introduced via the mouth opening. In the case of a container in the shape of a bottle, the mouth opening is the pouring opening on the bottle neck. However, the blank can also take the form of a container open at the top without a specific mouth, such as a bowl, a cup or a tray. These are provided with an opening which, when used as intended, usually points upwards. The pulp is accordingly introduced via the opening cross-section of the corresponding opening. However, it can also be provided that the mold in such wide-neck containers, such as a cup, is closed with a lid in the area of ​​the opening and a separate mouth is provided here in order to introduce the pulp into the mold.

[0016] After the pulp has been applied to the liquid reservoir, the liquid reservoir can be replaced by selectively draining the liquid reservoir through the mold. Draining the liquid reservoir causes the pulp to flow into the mold. The draining process can be controlled by applying positive pressure to the pulp. Additionally or alternatively, the liquid reservoir in the mold can be removed using negative pressure, so that the pulp is sucked into the mold.

[0017] The draining of the liquid supply can also be controlled, for example, by an orifice plate, so that the draining speed is limited or can be regulated by restricting the draining volume.

[0018] By draining the liquid supply, a flow of pulp can occur, particularly within the casting mold, and the inflowing pulp can settle on an inner wall of the casting mold, and thus the cavity.

[0019] By settling the pulp against the inner wall of the mold, the wall of the future blank is built up. Control or regulation, as mentioned above, using pressure or volume, can influence the settling process and, accordingly, the structure of the wall.

[0020] Additionally or alternatively, different pulps can be introduced into the mold one after the other. Such serial introduction of different pulps can create a layered structure of the blank within the mold. For example, pulps can be used that differ in color or in their properties, particularly their fiber properties or their functional properties, such as barrier properties.

[0021] It can be provided that the liquid supply is drained from the casting mold at several points. These points can correspond to different segments or areas of the future blank and thus also to the casting mold. By draining the liquid supply at several points, the flow of the pulp within the casting mold can be directed, so that the settling of the pulp can also be controlled and monitored. This allows the wall of the blank to be built up in a targeted manner and the amount and location of the deposited or settled pulp to be controlled.

[0022] Settling of the pulp here refers to the settling of the fibres contained in the pulp, in this case on the inner wall of the casting mould in the cavity.

[0023] It can be provided that the liquid supply is drained from the casting mold through several points in a specific time sequence.

[0024] This enables precise control of the pulp flow and thus the targeted distribution of the fibers. Accordingly, the structure of the blank wall can be precisely controlled, and a fiber distribution within the blank wall can be achieved that meets specific requirements.

[0025] For example, in areas subject to increased force, a thicker structure can be achieved than in the rest of the blank.

[0026] In this way, blanks can be created for containers, for example, which are optimized in terms of weight, stackability (top load), fiber orientation, and much more. By specifically depositing fibers, increased fiber deposition in places that are hardly subject to stress can be avoided. This is not possible with conventional processes. The wall thickness of the blank, and thus of the container, typically always corresponds to the wall thickness required to absorb the greatest force, since the processes normally used do not allow for targeted control of the fiber settling process. A corresponding casting mold can be provided with several drain openings that are opened in a specific time sequence. The term "draining" in this case refers to the discharge of liquid from the casting mold.

[0027] Preferably, the pulp is introduced into the mold under excess pressure. In particular, excess pressure is generated after the pulp has been applied to the liquid reservoir, i.e., during the draining of the liquid reservoir. The pressure can be built up, in particular, before the liquid reservoir is drained.

[0028] By building up excess pressure, the flow of the pulp can be controlled more precisely.

[0029] Before the pulp is introduced, the mold can be backflushed by filling it with process fluid. The process fluid can be discharged through a mold opening corresponding to the blank opening. This allows for easy backflushing of the mold, with the backflushing fluid and the process fluid preferably being identical. As soon as the backflushing process is stopped, the mold is already filled with a fluid supply as described here, and the pulp can be immediately applied to the fluid supply.

[0030] This simplifies the entire process. Fibers still present in the backwash liquid have no negative impact and are, at most, directly reused in subsequent steps and deposited accordingly in the mold. Since no further process steps are necessary between backwashing and the application of pulp, this process is also comparatively faster.

[0031] A further aspect relates to a mold for producing a fiber-based blank from pulp, in particular for carrying out the method for producing a fiber-based blank from pulp as described in the present method.

[0032] The mold is permeable to liquid and has at least one closable drain opening for draining liquid from the interior of the mold, in particular from a cavity. The mold has, in particular, a liquid-permeable cavity.

[0033] A closable drain opening allows a liquid supply to be provided within the mold and, at the same time, pressure to be built up, as the mold can be closed through the drain opening. Furthermore, the drain opening enables the creation of a specific flow within the mold when a liquid supply in the mold is replaced with pulp by draining it out. The resulting specific flow allows the settling of fibers from the pulp to be specifically controlled.

[0034] Alternatively, it can also be provided that the casting mold has several closable drain openings so that a liquid can be drained from the interior of the casting mold at several points.

[0035] As already described, a specific distribution of the pulp, i.e., a specific settling of the fibers from the pulp inside the mold, can be enforced through multiple outlet openings. This enables the specific and targeted construction of a container wall. In particular, by selectively opening or closing the individual outlet openings, the flow within the mold can be altered and the flow can be directed to different locations or segments of the mold in a chronological sequence.

[0036] The individual drain holes can be arranged at different heights in the direction from one opening in the blank to the bottom of the blank, and thus at corresponding positions on the casting mold. They can also be distributed around the circumference of the blank. This allows, for example, the creation of multiple drain levels.

[0037] It can be provided that the closable discharge openings are designed as valves, in particular as pinch valves. This allows, on the one hand, them to be opened and closed in a targeted manner, and, on the other hand, the volume discharged through the respective discharge openings can be controlled by changing the passage. This allows direct influence on the direction of the flow and also on its strength.

[0038] As already described, the casting mold has an outer boundary that is impermeable to liquid. The drain openings can thus be arranged in this outer boundary, which makes it possible to provide specific locations on the casting mold where increased flow occurs. These are the locations where the drain openings are located.

[0039] A further aspect relates to a manufacturing device comprising a casting mold for producing a fiber-based blank from pulp as described herein, in particular for producing a fiber-based blank according to the method as described herein.

[0040] The manufacturing device preferably has a control device for controlling the discharge openings.

[0041] By providing a manufacturing device, a coordinated system can be provided, with all components pre-adjusted to one another.

[0042] The method according to the invention is explained using schematic figures. It shows:

[0043] Figure 1: A casting mold; Figures 2A to 2E: individual process steps;

[0044] Figure 3 : examples of other typical fiber-based

[0045] Containers which can be produced by means of the method according to the invention;

[0046] Figure 4 shows an example of a typical fiber-based

[0047] Closure which can be produced by means of the method according to the invention.

[0048] Figure 1 shows a casting mold 20 for a blank for a container in the shape of a bottle. The casting mold 20 has two casting mold halves in the present case, although only one half is shown in Figure 1. A cavity 22 is arranged within the casting mold 20 and is enclosed by a liquid-impermeable outer boundary 23. The cavity 22 is permeable to water and in this case is formed from a metal grid or sieve. The liquid-impermeable outer boundary 23 has a hollow space 24 in which the cavity 22 is arranged. The casting mold 20 has a plurality of drain openings 21. The drain openings 21 connect an exterior of the casting mold 20 to the cavity 24. The mold 20 also has an inlet opening 25 that opens directly into the interior of the cavity 22. The outlet openings 21 are arranged at different heights and can thus define different outlet levels.

[0049] The position designation height is defined here on the basis of the illustration shown in Figure 1 and thus on the container in its position as used, i.e. in an upright form with a dispensing opening facing upwards and a container base facing downwards on which the container stands.

[0050] Valves are arranged at both the inlet opening 25 and the outlet openings 21 to close the respective openings. The inlet opening 25 can, as shown here, be provided with a branch 26, which can also be closed.

[0051] Figures 2A to 2E show individual method steps or process steps. These figures each show a simplified cross-section through the casting mold 20 according to Figure 1. As can be seen from Figure 2A, the casting mold 20 is filled with a process liquid 30, so that a liquid reservoir 31 is formed within the casting mold 20. The casting mold 20 is closed in the present case, i.e. the drain openings 21 are closed. The liquid reservoir 31 completely fills the hollow space 24 and also flows through the cavity 22, filling it as well.

[0052] The casting mold 20 is connected by its inlet opening 25 to a corresponding reservoir containing pulp 40. In the illustration according to Figure 2A, the pulp 40 has already been applied to the liquid reservoir 31 in the casting mold 20. The branch 26 at the inlet opening is closed.

[0053] From Figure 2B it can now be seen that the liquid supply 31 is specifically drained from the casting mold 20, in this case in the direction of the arrows PI through the drain openings 21 arranged at the top in the present illustration. For this purpose, these are opened. Pulp 40 now flows through the inlet opening 25 into the interior of the cavity 22. The fibers located in the pulp 40 are retained inside the casting mold 22, namely on the wall of the cavity 22. Here, a wall 101 of the later blank is built up. The fibers are essentially filtered out of the pulp, so that only the liquid portion of the pulp penetrates into the cavity 24. This is represented by the hatching which is different from that of the pulp 40.By appropriately opening or closing the discharge openings 21, a corresponding flow can be set within the casting mold 20 so that the fibers are deposited at desired locations or points within the cavity 22.

[0054] As soon as, for example, enough pulp has been deposited in the upper area in the present illustration, the now open drain openings 21 can be closed and other drain openings 21 opened. This can be seen, for example, from the illustration according to Figure 2C. Here, the drain openings 21 located further down in relation to the open drain openings 21 according to Figure 2B are opened. The process liquid 30 now flows out of the casting mold in the direction of the arrows P2 and the pulp 40 settles at other locations within the cavity 22. The wall 101 is further built up. In the next step, the drain opening 21 located furthest down can be opened. This is shown in Figure 2D. The process liquid 30 still remaining in the casting mold 20 is now completely displaced by the pulp 40 and flows in the direction of the arrow P3. The construction of the wall 101 of the blank 100 is now finished.

[0055] Subsequently, a valve at the inlet opening 25 is closed so that no further pulp can flow in. The liquid still remaining in the casting mold 20 is completely drained off and the resulting blank 100 is demolded. The casting mold 20 is now empty, although fiber residues from the pulp 40 may still adhere to the cavity 22. These fiber residues can be backflushed. In this process, process liquid 30 is introduced into the casting mold 20 through the drain openings 21. This is shown in Figure 2E by the arrows P4. As the process liquid flows in, fiber residues are released from the cavity 22 and discharged through the branch 26, which is shown by the arrow P5. For this purpose, the inlet opening 25 is closed and the branch 26 is opened. This prevents the process liquid from being flushed into the pulp reservoir. After a certain time, the drain openings 21 are closed and the flushing process is finished.At this point, the interior of the mold, i.e., the cavity 24 and the cavity 22, is again filled with process liquid 30, as shown in Figure 2A. The branch 26 can be closed, and new pulp can be added to the liquid supply by opening the inlet valve 25.

[0056] Figure 3 shows, by way of example, further typical fiber-based containers that can be produced using the method described here. A container 100 can be seen that corresponds to the container 100 from the description of Figures 1 and 2. This container 100 is also in the shape of a bottle and additionally has a thread on the bottle neck. The container 100' is in the shape of a bowl, and the container 100'' is in the shape of a cup.

[0057] Figure 4 shows an example of a typical fiber-based closure 300 that can be manufactured using the method described herein.

Claims

Patent claims 1. Method for producing a fiber-based blank, in particular a container (100, 100' , 100'' ) or a fiber-based closure element (300) for a container (100, 100' , 100'' ) from pulp (40) , comprising the steps - Providing a mold (20) , - Filling the mold (20) with a process fluid (30), in particular water, so that a liquid reservoir (31) is formed in the mold (20), - Applying pulp (40) to the liquid reservoir (31) in the mold (20) .

2. Method according to claim 1, characterized in that the liquid reservoir (31) is replaced after the pulp (40) has been applied to the liquid reservoir (31) by selectively draining the liquid reservoir (31) through the mold (20).

3. Method according to claim 2, characterized in that by draining the liquid supply (31) a flow of pulp (40) is created and the incoming pulp settles on an inner wall of the mold (20).

4. Method according to one of claims 2 or 3, characterized in that the liquid supply (31) is drained from the mold (20) at several points.

5. Method according to claim 4, characterized in that the liquid supply (30) is drained from the mold (20) through the multiple points in a specific temporal sequence.

6. Method according to one of claims 2 to 5, characterized in that after replacing the liquid supply (31) the container (100) formed by the deposition of the pulp (40) is removed from the mold (20). Method according to any one of claims 1 to 6, characterized in that the pulp (40) is introduced into the mold (20) under positive pressure. Method according to any one of claims 1 to 7, characterized in that the liquid supply in the mold (20) is removed under negative pressure, so that the pulp (40) is drawn into the mold (20). Method according to any one of claims 1 to 8, characterized in that different pulps are introduced successively into the mold (20) so that a layer-by-layer build-up of the blank can be produced within the mold. Method according to one of claims 1 to 9, characterized in that by filling the mold (20) with the process fluid (30) the mold (20) is backwashed before the pulp (40) is introduced.A mold (20) for producing a fiber-based blank from pulp (40), in particular for carrying out a method according to any one of claims 1 to 10, wherein the mold (20) is permeable to liquid, characterized in that the mold has at least one closable drain opening (21) for draining liquid from the interior (22) of the mold (20). A mold (20) according to claim 11, characterized in that the mold has several closable drain openings (21) so that a liquid can be drained from the interior of the mold (20), in particular from a cavity (24), at several points. Mold (20) according to claim 12, characterized in that the multiple closable drain openings (21) are arranged along the mold (20) in different planes. Mold (20) according to any one of claims 11 to 13, characterized in that the closable drain openings (21) are designed as valves, in particular as pinch valves. Mold (20) according to any one of claims 11 to 14, characterized in that it has an outer boundary (23) that is impermeable to liquids. Manufacturing device comprising a mold (20) according to any one of claims 11 to 15 for producing a fiber-based container (100) from pulp (40), in particular according to a method according to any one of claims 1 to 9. Manufacturing device according to claim 16, characterized in that the manufacturing device has a control device for controlling the drain openings (21).

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