Process for the manufacturing of a fiber-based product from pulp

Abstract

Disclosed is a process for manufacturing a fiber-based product from pulp, in particular a container or a fiber-based closure element for a container. The method comprises the steps of: - providing a mold; - introducing pulp into the mold such that a wet fiber-based preform (60) is formed; - drying the wet fiber-based preform; - cutting the dried preform (61) to size by cutting off an excess length (62).

Description

[0001] Process for producing a fiber-based product from pulp

[0002] The present invention relates to a method for producing a fiber-based product from pulp, in particular a container or a fiber-based closure element for a container, according to the preamble of the independent claim.

[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 in different properties, for example different wall thicknesses and therefore different strengths or different surfaces, and in particular in different dimensions of the same elements of different containers. Because the containers are formed in a negative mold, a very high level of dimensional accuracy can be achieved with regard to their outer contour. The inner contour, or rather the inner surface of the container, is subject to varying degrees of deviation depending on the specific properties of the pulp from which the container is formed.These are typically negligible, with the exception of deviations in the area of ​​a container opening where a container closure is arranged, or which is designed as a container neck with corresponding fastening elements for a container closure. Due to the material properties of the pulp, an upper, closing edge of the opening is subject to larger tolerances and is regularly fibrous.

[0006] This is particularly disadvantageous since it forms an interface to, for example, a container closure and this interface must be dimensionally accurate.

[0007] The object of the invention is to remedy at least one or more disadvantages of the prior art. In particular, a method is to be provided that enables fiber-based containers to be manufactured with precise dimensions, in particular, as independently as possible of material deviations in the container. Preferably, post-processing of the container should be dispensed with.

[0008] This problem is solved by the method defined in the independent patent claim. Further advantageous embodiments emerge from the dependent patent claims.

[0009] A method according to the invention for producing a fiber-based product from pulp, in particular a container or a fiber-based closure element for a container, comprises the following steps: - Providing a mold,

[0010] - Introducing pulp into the mold to form a wet fiber-based blank

[0011] - Drying the wet fiber-based blank

[0012] - Finishing the dried blank by cutting off any excess.

[0013] The sequential nature of these steps allows for the manufacture of a product from pulp that is dimensionally accurate and repeatable. The finishing of the dried blank ensures that every product has the same dimensional accuracy.

[0014] The product is preferably a container for liquids, in particular a drinks bottle.

[0015] To form the fiber-based blank, the pulp can be introduced into the mold using the following steps:

[0016] - Filling the mold with a process liquid, especially water, so that a liquid reserve is formed in the mold,

[0017] - Applying pulp to the liquid supply

[0018] - Replacing the liquid supply by deliberately draining the liquid supply through the casting mold.

[0019] 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.

[0020] By adding 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. So when the pulp is added to the liquid supply, these two media do not mix. The liquid supply is essentially replenished by the pulp. The liquid supply therefore provides a standing column of water, which is simply extended by adding pulp to this column of water.

[0021] A mold for producing a fiber-based blank is typically liquid-permeable 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 design, the mold can be formed, for example, from a metal grid having an outer boundary that is impermeable to liquid, so that a liquid supply can be provided within this mold. In a simple design, the outer boundary can be provided, for example, by a container, which container can be flooded.

[0022] 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.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.

[0023] The discharge process can be controlled by applying positive pressure to the pulp. Additionally or alternatively, the liquid supply in the mold can be removed using negative pressure, so that the pulp is sucked into the mold.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] Additionally or alternatively, different pulps can be introduced into the casting mold one after the other. By introducing different pulps in series in this way, a layered structure of the blank can be created within the casting mold. For example, pulps can be used that differ in color or in their properties, in particular their fiber properties or their functional properties, such as barrier properties. 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 later blank and thus also to the casting mold.

[0028] By draining the liquid supply at multiple points, the flow of pulp within the mold can be directed, allowing the settling of the pulp to be controlled. 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 precisely controlled.

[0029] 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.

[0030] It can be provided that the liquid supply is drained from the casting mold through several points in a specific time sequence.

[0031] 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.

[0032] For example, in areas subject to increased force, a thicker structure can be achieved than in the rest of the blank.

[0033] This makes it possible to create blanks for containers, for example, that are optimized in terms of weight, stackability (top load), fiber orientation, and much more. Targeted fiber deposition can prevent increased fiber deposition in areas subject to little stress. 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 targeted control of the fiber deposition process is not possible with the processes commonly used.

[0034] It may be provided that a corresponding casting mold has several drain openings that are opened in a specific temporal sequence. The term "draining" in this case refers to the discharge of liquid from the casting mold.

[0035] 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.

[0036] By building up excess pressure, the flow of the pulp can be controlled more precisely.

[0037] 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.

[0038] 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.

[0039] To dry the blank, at least the following steps may be required:

[0040] - Providing the fiber-based blank in a microwave-permeable press mold,

[0041] - Inserting an expandable tool into the fiber-based blank,

[0042] - Expanding the expandable tool so that the fiber-based blank is pressed to reduce the water content of the fiber-based blank,

[0043] - Exposure of the pressed blank to microwaves.

[0044] By placing the fiber-based blank in a microwave-transparent mold, the wet fiber-based blank can remain within the mold during the drying process, i.e., while it is being exposed to microwaves. The container is thus protected from external influences and damage or deformation is prevented. By placing the wet fiber-based blank within the microwave-transparent mold, it can also be achieved that it is accessible to the microwaves from all sides, thus allowing drying from all sides. After this drying step, the wet fiber-based blank has a water content of approximately 5% to 12%.

[0045] In the present process, the wet fiber-based blanks are typically formed as described herein. In other words, pulp is introduced into a porous mold or a solid mold with water-draining channels whose entrances are covered with screens or whose openings are small enough that the pulp fibers cannot penetrate, and the pulp fibers are washed onto the inner wall of the mold so that a container wall is built up. As soon as the wall is sufficiently thick, the washing of the pulp is stopped. The now available semi-finished product, i.e. the wet fiber-based blank, is removed from the mold and placed in the microwave-permeable mold and thus made available in the mold. At this point, the wet fiber-based blank has a water content of approximately 75% or less, so that it can be transported between the processing stations with its dimensionally stable.

[0046] The wet fiber-based blank is removed from the mold using a suitable transfer device. The wet fiber-based blank is then inserted into the open mold. The mold is preferably constructed in two parts. Blowing and / or suction using negative or positive pressure may be necessary for removal and insertion. Purely mechanical grippers can also be used for this transfer.

[0047] Typically, the press mold may have an inner wall that is designed with a higher surface quality than the inner wall of the casting mold.

[0048] Preferably, after the fiber-based blank has been provided in the press mold, an expandable tool is inserted into the fiber-based blank. By expanding the expandable tool, the water content of the fiber-based blank can be reduced in a first step by compressing a wall of the blank. At this point, the wet fiber-based blank has a water content of approximately 50%-60%.

[0049] At the same time, a surface with improved properties can be created on the wet fiber-based blank because, as already explained, the compression mold can be of higher quality than the casting mold. It can be provided that the expandable tool remains in the expanded state during the application of microwaves. In other words, the expansion of the expandable tool and the application of microwaves to the pressed blank occur simultaneously. The blank remains in the compression mold.

[0050] Pressure can be maintained on the wall of the wet fiber-based blank. Furthermore, the expandable tool remaining inside the wet fiber-based blank provides internal support, preventing unwanted deformation. This also improves the surface quality of the blank.

[0051] The fiber-based blank can be placed in a microwave-reflecting microwave chamber before exposure to microwaves, in particular together with the press mold.

[0052] This can increase the effectiveness of the microwaves. Microwaves that are not directly absorbed by the wet fiber-based blank are typically reflected off the interior walls of the microwave chamber, increasing the likelihood that these microwaves will also reach the blank being dried.

[0053] It is generally known that microwave excitation can cause molecules to vibrate, and that this vibration generates heat. Water, for example, has a natural frequency of 2.45 GHz. Microwaves are therefore preferably generated at this frequency. To remove water or residual moisture from the wet fiber-based blank, the water is preferably heated until it evaporates and is then released from the wet blank.

[0054] In order to accelerate the drying process, it can be provided that the mold and / or the microwave chamber is preheated to a temperature which is higher than 60 ° C but preferably lower than 160 ° C.

[0055] This also prevents the moisture escaping from the wet fiber-based blank from condensing again in the immediate vicinity of the blank and precipitating as drops.

[0056] Heating can be achieved, for example, using conventional resistance heaters. Additionally or alternatively, it is conceivable to blow in a suitably heated fluid, such as air, so that the respective elements reach the desired temperature.

[0057] An additional or alternative possibility of preheating the press mold could, for example, also be achieved by deliberate, partial absorption of the microwave radiation in the press mold itself in the order of maximum 10%, preferably maximum 5% of the microwave radiation or by the energy transfer of the steam generated during drying to the press mold.

[0058] It may be possible to remove the moisture through a forced airflow. This moisture can be either water vapor or water in its liquid form.

[0059] By forced removal, the humidity within the device can be kept low and condensation of the moisture or reheating of the moisture, for example of water droplets by microwave radiation, can be prevented.

[0060] To improve drying and / or evaporation of moisture from the wet fiber-based blank, it can also be rotated during microwave exposure. This makes the energy input into the wet fiber-based blank more uniform, and overheating of individual areas of the blank can be avoided.

[0061] It may be possible to expose several blanks to microwaves simultaneously. For this purpose, several blanks, in particular several molds each containing one blank, may be introduced into the microwave chamber simultaneously. This reduces the cycle time or increases the number of dried blanks per unit of time, and enables more efficient use of the microwaves.

[0062] The blanks can be rotated around their own axis and / or around a common axis. This allows for more efficient use of the microwaves and a more even energy input into the blanks.

[0063] Additionally or alternatively, it would also be conceivable to provide one or more molds that can accommodate multiple blanks simultaneously. This simplifies the device, since each blank does not have to be handled individually when it is in a multiple mold.

[0064] It was determined that several individual molds, including blanks, can be arranged in any spatial arrangement within the microwave chamber. This arrangement has no influence on the uniformity of the energy input.

[0065] Additionally or alternatively, a rotating element, a so-called stirrer, may be provided, particularly within the microwave chamber or at the transition from a waveguide to the microwave chamber, to swirl the microwaves. A stirrer can disrupt the static propagation of the microwaves within the drying chamber, i.e., the microwave chamber, and minimize areas of high microwave intensity. Such an arrangement also has a positive effect on uniform energy input.

[0066] Another way to improve quality is to apply microwaves in a timed fashion depending on the water content of the wet fiber-based blank. This timed fashion allows for a reduction in power. Typically, toward the end of the drying process, the water content in the wet fiber-based blank is lower, and excessive energy can cause the blank to overheat in certain areas. This can be prevented by reducing the power.

[0067] The microwave-transparent mold can be made of a material selected from the list of materials including PEI, PI, PE, POM, PEEK, wood, PTFE, ceramic, glass, and PP. The mold can be porous or solid with water-draining channels or made of a fine-mesh material.

[0068] It can be seen that the blank remains in the press mold during the entire drying process.

[0069] It can be provided that in order to assemble the dried blank and thus to produce the fibre-based product, the excess protrusion is cut off with a laser beam.

[0070] By providing a laser or a laser beam to cut off the excess material, a very precise cutting edge can be created.

[0071] It can be provided that the dried blank and the laser beam are moved relative to each other during the separation of the excess protrusion.

[0072] The relative movement of the laser beam with respect to the dried blank makes it possible to move the laser beam at a constant distance from the surface of the excess material to be removed, while also maintaining a specific angle of the laser beam with respect to the surface. In other words, this configuration allows the angle of the cutting edge to be kept constant along the surface over the entire length of the cutting edge. This also results in a very flat cutting edge. Waviness of the cutting edge can be prevented.

[0073] The relative movement is preferably a rotational movement of the container in relation to the laser beam, rather than a movement of the laser beam in the circumferential direction of the blank.

[0074] A cutting device for processing the dried blank comprises a holding device for holding the dried blank. It also comprises a cutting laser for generating a laser beam, wherein the laser beam of the cutting laser and the dried blank are movable relative to one another by means of the laser beam for cutting off any excess portion of the dried blank.

[0075] It can be provided that the laser beam is guided in a deflection device and that this deflection device is rotated about a longitudinal axis of the dried blank in order to cut off the excess projection in order to generate the relative movement.

[0076] Such a process step can provide a simple process sequence that can be precisely adjusted and reproduced.

[0077] The laser beam can be focused onto the surface of the excess material to be removed using focusing optics, or the focus of the laser beam can be adjusted to a specific distance from the surface. This distance can be zero or negative, so that the focal point lies within the material thickness. This type of focusing optics and appropriate focusing can enable a clean cut.

[0078] To perform the cut, the laser beam can be positioned and activated in the direction of the longitudinal axis above a final cutting surface. The laser cut exhibits a vertical movement component up to a cutting position of the final cutting surface.

[0079] In particular, this vertical movement component is also superimposed with a movement component directed in the circumferential direction of the fiber-based product, so that an essentially grinding cut is created.

[0080] By positioning and activating the laser beam above the final cutting surface, defects that occur when the laser beam is activated can be prevented. Typically, more energy is introduced when the laser beam first passes through the object to be cut, resulting in a localized burn on the object to be cut. By positioning the laser beam above the final cutting surface, this localized burn is not in the area of ​​the final cutting surface.

[0081] Preferably, after completing the cut of the final cutting surface, the laser beam is moved in the direction of the longitudinal axis across the final cutting surface before deactivating the laser beam. The laser cut has a vertical movement component until the final position at which the laser beam is deactivated.

[0082] Just as at the beginning of the cut, increased energy input may occur at the end of the cut, resulting in burn marks. The vertical movement component can keep the burn marks away from the final cut surface. Here, too, the vertical movement component preferably has a superimposed movement component directed in the circumferential direction of the dried blank. This also creates a grinding cut.

[0083] The laser beam can be switched on and off while the laser is moving downwards or upwards, respectively, and the dried blank and the laser beam already exhibit the movement component directed in the circumferential direction of the dried blank. This also reduces the risk, or at least the extent, of a localized burn.

[0084] Preferably, the radial distance of a focusing optics from the longitudinal axis is initially set according to a product-specific parameter. This ensures that the focal point of the laser beam is always at the desired distance from the surface of the excess material to be cut off, thus creating a cutting surface of correspondingly high quality.

[0085] The product-specific parameter can be determined individually for each fiber-based product / dried blank. It is conceivable that each product is measured before the cutting process, and the corresponding data is transferred to the cutting device, which then performs the cut with a static setting.

[0086] This parameter can also be set for entire batches, for example if they are manufactured within a narrow tolerance range.

[0087] In other words, a predefined profile can be transferred to the cutting device, allowing the radial adjustment of the focusing optics to be continuously adjusted according to the profile throughout the cut. However, it is also conceivable that the radial distance is continuously adjusted to the contour of the dried blank during the separation or cutting process.

[0088] In this way, a continuous adjustment of the radial distance can be ensured, which makes it possible for the distance between the focusing optics and thus the focal point of the laser beam to the surface of the excess material to be cut off to remain the same over the entire cutting process.

[0089] It would also be conceivable that, for example, in the case of uneven or unknown surface contours, this would be measured in real time and the radial distance of the focusing optics would be continuously adjusted.

[0090] To increase the quality of the cut edge, purge gas can be blown into the dried blank during the cutting process by means of a purge device. By blowing in purge gas in this way, dirt and particles that arise during the cutting process can be blown out of the interior of the blank or are prevented from settling inside the dried blank. Additionally or alternatively, it can be provided that during the cutting process, exhaust air is sucked out of the dried blank, in particular from the interior of the dried blank, using a second suction device and / or from the area of ​​an outlet nozzle using a first suction device.

[0091] This contributes to an increase in cutting quality and subsequent cleaning of the cutting edge can be omitted.

[0092] Additionally or alternatively, it can be provided that the deflection device is supplied with purge gas during the separation process.

[0093] On the one hand, this prevents dust or dirt particles from settling and / or accumulating in the deflection device, and in particular on the deflection mirrors arranged therein or thereon. On the other hand, by applying purge gas to the deflection device at an outlet nozzle, a protective gas flow can be generated, which provides protection against external influences in the cut area. Such a protective gas flow can, in particular, prevent dirt or dust particles from entering the laser beam.

[0094] After the cutting process, the cut-off excess material can be stripped off the cutting device by means of a stripping ring.

[0095] The excess material can then be disposed of in a targeted manner, for example, in the direction of a separately arranged funnel or container.

[0096] After finishing, a powder coating can be applied to the finished opening of the dried blank. Applying a powder coating makes it possible to seal the cutting edge.

[0097] A powder coating can also be applied to the inside of the dried blank after assembly. This allows the blank's interior to be sealed and / or sealed.

[0098] Additionally, a powder coating may be applied to the outer side of a neck region of the dried blank after assembly. However, at least a portion of the outer side of the dried blank remains uncoated, meaning that the outer side is partially uncoated.

[0099] By coating the outside of the neck area, it can also be sealed and / or made more durable during use. The uncoated area on the outside of the blank allows the product to be recycled. The uncoated area provides a surface where the product can be broken open or softened using water. This makes the product easier to recycle.

[0100] A meltable polymer can be applied as a powder coating. Polymers have advantageous properties and are easy to process.

[0101] To apply the powder coating, it can be electrostatically charged. In particular, a conductive mold surrounding the mold can be charged with the opposite polarity to the powder. The powder then deposits itself, particularly on the inside of the blank, and adheres there.

[0102] The powder coating can then be melted in an oven under the influence of heat, creating a continuous film. The applied powder coating is thus exposed to thermal energy, transforming the powder into a melt. The melting process creates a homogeneous film that provides a suitable seal. This film preferably extends from the inside over the finished opening to an outer area of ​​the neck, forming a continuous seal in this area.

[0103] It may be necessary to test the dried blank for leaks. This can prevent defective products from being sold.

[0104] After sealing, i.e., after melting the powder coating and subsequent cooling, a product can be poured into the dried blank, which can then be sealed with a closure. This creates a sealed body for transporting and protecting liquid products. In particular, by sealing the packaging edge, a reliable seal can be created in this area using a suitable sealing cone or sealing layer, for example, made of a sealing material such as a liner.

[0105] The method according to the invention is explained using schematic figures. It shows:

[0106] Figure 1 : A casting mold;

[0107] Figures 2A to 2E : individual process steps;

[0108] Figure 3 : A device before exposure to microwaves;

[0109] Figure 4 : the device according to Figure 3 during exposure to microwaves

[0110] Figure 5 : A perspective view of a

[0111] cutting device;

[0112] Figure 6: a sectional view through the cutting device according to Figure 5;

[0113] Figure 7 : a detailed view from Figure 6 ;

[0114] Figure 8 : a perspective view of a dried blank;

[0115] Figure 9 : a powder coating process;

[0116] Figure 10 : the drying step of the powder coating process;

[0117] Figure 11 : a leak test;

[0118] Figure 12: the closing process; Figure 13: examples of other typical products that can be produced using the method according to the invention;

[0119] Figure 14 : example of a typical fiber-based

[0120] Closure which can be produced by means of the method according to the invention.

[0121] In the following figures, individual process steps of the process according to the invention are each described separately. Figures 1 to 2E describe the provision of a casting mold and the introduction of the pulp into the casting mold. Figures 3 and 4 describe a possible and preferred drying step. Figures 5 to 8 describe a preferred process for processing the dried blank. Finally, Figures 9 to 12 describe final processing steps and Figures 13 and 14 describe possible applications.

[0122] Figure 1 shows a casting mold 70 for a blank for a container in the shape of a bottle. The casting mold 70 has two casting mold halves in the present case, although only one half is shown in Figure 1. A cavity 72 is arranged within the casting mold 70 and is enclosed by a liquid-impermeable outer boundary 73. The cavity 72 is permeable to water and in this case is formed from a metal grid or sieve. The liquid-impermeable outer boundary 73 has a hollow space 74 in which the cavity 72 is arranged. The casting mold 70 has a plurality of drain openings 71. The drain openings 71 connect an exterior of the casting mold 70 to the cavity 74. The mold 70 also has an inlet opening 75 that opens directly into the interior of the cavity 72. The outlet openings 71 are arranged at different heights and can thus define different outlet levels.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.

[0123] Both at the inlet opening 75 and at the outlet openings

[0124] 71 valves are arranged to close the respective openings.

[0125] The inlet opening 75 can, as shown here, be provided with a branch 76, which can also be closed.

[0126] Figures 2A to 2E show individual method steps or process steps. These figures each show a simplified cross section through the casting mold 70 according to Figure 1. As can be seen from Figure 2A, the casting mold 70 is filled with a process liquid 95, so that a liquid reservoir 96 is formed within the casting mold 70. The casting mold 70 is closed in the present case, that is, the drain openings 71 are closed. The liquid reservoir 96 completely fills the cavity 74 and also flows through the cavity

[0127] 72 and fill this out as well.

[0128] The mold 70 is connected by its inlet opening 75 to a corresponding reservoir or process tank containing pulp 90. In the illustration according to Figure 2A, the pulp 90 has already been applied to the liquid supply 96 in the mold 70. The branch 76 at the inlet opening is closed.

[0129] From Figure 2B it can now be seen that the liquid supply 96 is specifically drained from the casting mold 70, in this case in the direction of the arrows PI through the drain openings 71 arranged at the top in the present illustration. For this purpose, these are opened. Pulp 90 now flows from the reservoir through the inlet opening 75 into the interior of the cavity 72. The fibers located in the pulp 90 are retained inside the casting mold 72, namely on the wall of the cavity 72. This is where 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 74. This is represented by the hatching which is different from that of the pulp 90.By appropriately opening or closing the discharge openings 71, a corresponding flow can be set within the casting mold 70 so that the fibers are deposited at desired locations or points within the cavity 72.

[0130] As soon as, for example, enough pulp has been deposited in the upper area in the present illustration, the now open drain openings 71 can be closed and other drain openings 71 opened. This can be seen, for example, from the illustration according to Figure 2C. Here, the drain openings 71 located further down in relation to the open drain openings 71 according to Figure 2B are opened. The process liquid 95 now flows out of the casting mold in the direction of the arrows P2 and the pulp 90 settles at other locations within the cavity 72. The wall 101 is further built up. In the next step, the drain opening 71 located furthest down can be opened. This is shown in Figure 2D. The process liquid 95 still remaining in the casting mold 70 is now completely displaced by the pulp 90 and flows in the direction of arrow P3. The construction of the wall 101 of the blank 60 is now complete.

[0131] A valve at the inlet opening 75 is then closed so that no further pulp can flow in. The liquid still remaining in the casting mold 70 is completely drained off and the resulting blank 60 is demolded. The casting mold 70 is now empty, although fiber residues from the pulp 90 may still adhere to the cavity 72. These fiber residues can be backflushed. In this process, process liquid 95 is introduced into the casting mold 70 through the drain openings 71. This is shown in Figure 2E by the arrows P4. As the process liquid flows in, fiber residues are released from the cavity 72 and discharged through the branch 76, which is shown by the arrow P5. For this purpose, the inlet opening 75 is closed and the branch 76 is opened. This prevents the process liquid from being flushed into the pulp reservoir. After a certain time, the drain openings 71 are closed and the flushing process is finished.At this point, the interior of the mold, i.e., the cavity 74 and the cavity 72, is again filled with process fluid 95, as shown in Figure 2A. The branch 76 can be closed, and new pulp can be added to the fluid supply by opening the inlet valve 75.

[0132] For demolding, the wet fiber-based blank 60 is removed from the mold 70 using a suitable transfer device. For this purpose, the mold 70 is opened. The wet fiber-based blank 60 is then inserted into the opened mold 20, which is designed in two parts for this purpose.

[0133] Figure 3 shows a device 200 for reducing the water content in a fiber-based blank prior to exposure to microwaves. The fiber-based blank 60 is a container in the form of a bottle. This process is the drying step. It is carried out using microwave radiation. This step is described below with reference to the device 200.

[0134] The device 200 has a microwave chamber 40 which is closed with a lid 41. In the lid 41 there is an exhaust air opening 42 through which compressed air and / or moisture, such as water or water vapor, can be discharged. The microwave chamber 40 also has a floor 43. In the floor there are a plurality of openings 44 through which supply air can be introduced into the microwave chamber 40. The device 200 also has a device 50 for generating microwaves. In the present case this is designed as a magnetron. The device 50 for generating microwaves is connected to the microwave chamber 40 by a waveguide 51. The waveguide 51 is rectangular.

[0135] In the device 200, a mold 20 is arranged within the microwave chamber 40. A wet fiber-based blank 60 is arranged within the mold 20. This blank was taken from a casting mold before being introduced into the mold 20 and currently has a water content of approximately 75%. After the wet fiber-based blank 60 was introduced into the mold 20, an expandable tool 30 was introduced into the interior of the wet fiber-based container 100.

[0136] By expanding the expandable tool 30, the wall of the blank 60 is pressed onto the inner wall of the press mold 20 and the water or moisture contained in the wet fiber-based blank 60 is partially pressed out of it. For this purpose, the press mold 20 is designed to be permeable to water. The water permeability can be achieved with porosity; alternatively, individual channels or openings can be provided in the press mold. The water can also be drained off through gaps or openings at the separation point of the press mold. The escaping water or moisture is represented stylized by water droplets in the illustration according to Figure 3. These water droplets can drip onto the floor 43 of the microwave chamber and be discharged through the openings 44. After this step, the fiber-based container 100 has a water content of approximately 50%.Figure 4 shows the device according to Figure 3 during the exposure of the wet fiber-based blank 60 to microwaves. Figure 4 therefore shows the actual drying process. In the device 50 for generating microwaves, microwaves are generated accordingly and are introduced into the microwave chamber 40 through the waveguide 51. The microwaves heat up the moisture in the fiber-based blank 60; in other words, the molecules begin to vibrate. The moisture begins to evaporate and escapes from the blank 60 through the microwave-permeable mold 20. In Figure 4, the expandable tool 30 is shown in the non-expanded state; however, it is possible for the expandable tool 30 to remain expanded even during the process shown here. The moisture, represented here stylized by wavy lines, enters the microwave chamber 40.To prevent this moisture from condensing in the microwave chamber 40, air is blown in through the openings 44 in the floor 43 of the microwave chamber 40. This blown-in air flows out of the microwave chamber 40 through the exhaust air opening 42. This creates a flow within the microwave chamber 40 through which the moisture can be removed from the microwave chamber 40.

[0137] In this case, it can be provided for the press mold 20 to be provided with a moisture-dissipating channel into which a gap opens, which is arranged on or in the mold parting plane of the press mold 20. In this configuration, the moisture does not escape from the press mold 20 and into the microwave chamber 40 as shown, but is collected in the moisture-dissipating channel. Accordingly, the moisture can be discharged directly from the press mold 20 to the outside of the microwave chamber 40. Corresponding exhaust air openings of the microwave chamber 40 are then directly connected to the moisture-dissipating channel. In the present case, a holding device for the microwave-permeable press mold 20 is designed as an integral component of the cover 41. However, it is also conceivable for the device 200, for example, to be designed in two parts, i.e. to consist of two halves and, if appropriate, of a separate base.For example, the press mold 20 can be held and pressed together by corresponding elements on the respective halves of the device 200.

[0138] After this drying step, the now dried blank 61 is removed from the mold 20. For this purpose, the mold is opened. Using a suitable transfer device, for example a gripper, the dried blank 61 is fed to a finishing device, and the dried blank is finished accordingly. This step is explained below with reference to a cutting device 400.

[0139] Figure 5 shows a perspective view of a cutting device 400. The cutting device 400 comprises a holding device 450 for holding a dried blank 61. The cutting device 400 also comprises a cutting laser 420 which, in the present case, is arranged in a fixed location on the cutting device 400. A support 432, on which a pivot bearing 431 is arranged, is arranged above the dried blank 61. The support 432 is displaceable vertically along the longitudinal axis X. The longitudinal axis X essentially corresponds to a longitudinal axis through the dried blank 61 and, in the case of a rotationally symmetrical dried blank 61, as shown here, the longitudinal axis X corresponds to the axis of rotation.

[0140] For the sake of clarity, feeding devices for feeding the dried blanks 61 and for removing the dried blanks 61 are not shown.

[0141] Figure 6 shows a sectional view through the cutting device 400 according to Figure 5. The section extends transversely to the longitudinal extent of the laser 420 through the longitudinal axis X. In the lower region of the cutting device 400 in Figure 6, the holding device 450 is arranged, by means of which a dried blank 61 is held in the cutting device 400. Above the holding device 450, a vertically displaceable support 432 is arranged, on which a pivot bearing 431 is arranged. A deflection device 430 for guiding the laser beam 421 is arranged on the pivot bearing 431. The laser beam 421 is generated by means of the laser 420. The laser beam 421 is generated in such a way that it radiates essentially from the output side of the laser 420 in the direction of the longitudinal axis X. The laser beam 421 is deflected by means of the deflection device 430 so that it is directed essentially at right angles to the dried blank 61.This is explained in detail below with reference to Figure 7. The pivot bearing 431 is arranged such that the deflection device 430 is movable about the longitudinal axis X, wherein the longitudinal axis X and the center of rotation lie substantially one above the other. In the present case, the deflection device comprises individual tubes 424, 425, 426 and 427, which are each arranged at an angle to one another. Deflecting mirrors 423 for deflecting the laser beam 421 are arranged within the tubes at the respective interfaces of the individual tubes. Their function is explained below with reference to Figure 7. The length of the tube 424 of the deflection device 30 is variable in size, so that the support can be moved vertically together with the pivot bearing 431 and the remaining elements of the deflection device 430. The tube 425 of the deflection device 430 is also variable in its length, so that a radial distance between the tubes 426 and 427 with respect to the longitudinal axis X can be adjusted.

[0142] Figure 7 shows a detailed view of Figure 6. As can be seen, a plurality of deflecting mirrors 422 are arranged in the deflection device 430. Downstream in the direction of the laser beam, i.e. downstream in the direction of incidence, a safety element 423 is arranged for each deflection mirror 422, which in the present case is designed as a metal plate. Further arranged on the deflection device 430 is a focusing optics 440 for focusing the laser beam and downstream in the beam direction is an outlet nozzle 428. As explained in relation to Figure 6, the radial distance of the deflection device, or of the elements of the deflection device downstream of the pivot bearing 431, is adjustable. For this purpose, an actuator 433 is arranged below the pivot bearing 431. By actuating the actuator 433, the distance of the focusing optics 440 from the longitudinal axis X can be adjusted.This makes it possible to adjust a distance of the focal point of the laser beam 421 in relation to the surface of the projection 62 to be separated (see Figure 8).

[0143] In the present case, the deflection device 430 forms a substantially closed system into which a purge gas can be introduced, which flows through the outlet nozzle 428 during operation. The holding device 450 can also be seen in the illustration according to Figure 7. This has two grippers 451 and 452 which hold a dried blank 61 from two sides. A purge device 480 is introduced into the dried blank 61, through which purge gas can be introduced into the interior of the dried blank 61. During operation, or during the cutting process, the introduction of purge gas can prevent dirt or dust particles from becoming trapped inside the dried blank 61.Integrally formed in the rinsing device 480 is a second suction device 481, which, above the dried blank 61, or above an opening in the dried blank 61, sucks away the purge gas introduced into the dried blank 61, together with any dirt particles contained therein. A first suction device 460 is arranged outside the dried blank 61, specifically in the region of the outlet nozzle 28. The first suction device 460, on the one hand, sucks away dirt and dust particles that form outside the dried blank 61, and on the other hand, at least a portion of the purge gas can be recaptured from the deflection device 430.

[0144] The illustration in Figure 7 shows the cutting device 400 during operation. Before this state is reached, both the deflection device 430 and the first suction device 460 and the rinsing device 480 are arranged vertically above the dried blank 61. All of these elements are jointly attached to the pivot bearing 431 and can be moved vertically with the support 432.

[0145] In order to cut off an excess overhang 62 of the dried blank 61 (see Figure 8), these aforementioned elements are moved vertically in the direction of the dried blank 61, wherein during the vertical movement the pivot bearing 431, together with the deflection device 430 and all elements arranged on the pivot bearing 431, begins to rotate about the longitudinal axis X. At this point in time, the laser is also started up so that it reaches its preset power during the vertical displacement process and also during the rotation and shoots through the dried blank 61 above the final cutting edge 65 (see Figure 8).

[0146] After reaching the final vertical position, the pivot bearing 431 is moved by a further 360 ° and then the support 433 is moved upwards again in the vertical direction and the laser 420 is then switched off.

[0147] In Figure 7, a protective plate is also shown opposite the outlet nozzle 428, which prevents the uncontrolled spreading of the laser beam in the event of failure.

[0148] Figure 8 shows a perspective view of a dried blank 61. In the upper area, in the neck area, the dried blank 61 is shown cut, so that the cut edge 65 is clearly visible. The cut therefore extends only through the excess projection 62. After the cutting process, the cut edge 65 forms a final upper edge or upper opening of the dried blank 61, to which a corresponding lid can be applied.

[0149] After this processing, the dried blank 61, which is now finished and therefore already in the form of a fiber-based product, can be subjected to further processing steps.

[0150] For example, in a subsequent step, the interior of the dried blank 61 can be coated and / or the dried blank 61 can be fed to a filling system.

[0151] A coating step is explained below with reference to Figure 9. The now finished blank 61 is fed to a powder coating system (not shown in detail here). In the next step, an electrostatically charged lance 35 is introduced into the finished blank 61. This is located in an oppositely charged casing (also not shown here). Due to the electrostatic charge of the applied powder, it adheres to the inner side 63 of the finished blank 61.

[0152] The now coated, finished blank 61 is transferred to a furnace, as shown in Figure 10, and subjected to thermal energy. This melts the powder coating, creating a continuous, homogeneous film. The blank 61 is thus sealed.

[0153] The blank 61 can then be tested for leaks using a corresponding testing device 500, as shown in Figure 11.

[0154] The blank 61 can then be closed with a lid 300, as shown in Figure 12. Figure 13 shows examples of other typical fiber-based products that can be manufactured using the method described here. For example, a container 100 in the shape of a bottle is shown. This also 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.

[0155] Figure 14 shows an example of a typical fiber-based closure 300 that can be manufactured using the method described herein.

Claims

Patent claims 1. A method for producing a fiber-based product from pulp (40), in particular a container (100, 100', 100'') or a fiber-based closure element (300) for a container (100, 100', 100''), comprising the steps - Providing a casting mold (70), - Introducing pulp (40) into the mold (70) so that a wet fiber-based blank (60) is formed - Drying the wet fiber-based blank (60) - Assembling the dried blank (61) by cutting off an excess protrusion (62).

2. Method according to claim 1, characterized in that to form the fiber-based blank (60) the pulp (40) is introduced into the mold (70) with the following steps: - filling the casting mould (70) with a process liquid (95), in particular water, so that a liquid reservoir (96) is formed in the casting mould (70), - Applying pulp (40) to the liquid supply (96) - Replacing the liquid supply (96) by selectively draining the liquid supply (96) through the mold (70) .

3. Method according to one of claims 1 or 2, characterized in that at least the following steps are carried out to dry the blank (60): - Providing the fiber-based blank (60) in a microwave-permeable mold (20), - introducing an expandable tool (30) into the fiber-based blank (60), - Expanding the expandable tool (30) so that the fiber-based blank (60) is pressed to reduce the water content of the fiber-based blank, - Exposing the pressed blank (60) to microwaves so that a dried blank (61) is provided. Method according to claim 3, characterized in that the expansion of the expandable tool (30) and the exposure of the pressed blank (60) to microwaves occur simultaneously. Method according to one of claims 1 to 4, characterized in that for finishing the dried blank (61), the excess projection (62) is cut off with a laser beam (421). Method according to claim 5, characterized in that for cutting off the excess projection (61), the dried blank (61) and the laser beam (421) are moved relative to one another so that a finished opening is formed. Method according to claim 6, characterized in that a powder coating is applied to the finished opening of the dried blank (61) after finishing.Method according to one of claims 1 to 7, characterized in that a powder coating is applied to an inner side (63) of the dried blank (61) after finishing. Method according to one of claims 1 to 8, characterized in that a powder coating is applied to an outer side of a neck region of the dried blank (61) after finishing, wherein the dried blank (61) remains uncoated on its outer side, at least in some regions. Method according to one of claims 7 to 9, characterized in that a meltable polymer is applied as the powder coating. Method according to claim 10, characterized in that the powder coating is electrostatically charged for application. Method according to one of claims 7 to 11, characterized in that the powder coating is melted under the influence of heat in an oven so that a coherent film is formed. Method according to one of claims 1 to 12, characterized in that the dried blank (61) is tested for leaks. Method according to one of claims 1 to 13, characterized in that a product is filled into the dried blank (61) and the dried blank is subsequently closed with a closure.

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