Press mold for receiving a fiber-based blank, and method for reducing the water content in a fiber-based blank

Abstract

The invention relates to a press mold (20) for receiving a fiber-based blank, in particular a container (100, 100', 100'') or a fiber-based closure element (300) for a container (100), for use in a microwave chamber (40). The press mold (20) is permeable to microwaves, and at least one gap (21) through which moisture can escape is formed on the press mold (20) in the closed state of the press mold (20). The invention additionally relates to a method for reducing the water content in a fiber-based blank.

Description

[0001] Press mold for receiving a fiber-based blank and method for reducing the water content in a fiber-based blank

[0002] The present invention relates to a press mold for receiving a fiber-based blank, in particular for receiving a container or a fiber-based closure element, and to a method for reducing the water content in a fiber-based blank, in particular in a container or in a fiber-based closure element for a container according to the preamble of the independent claims.

[0003] A fiber-based blank in the form of a container was disclosed in WO 2012 / 139590 A1. To produce 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 accordingly. The pulp is compressed and heated to a temperature of approximately 180°C to dry the container. It is also known to produce closure elements for containers from pulp.

[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] The aforementioned process is time-consuming and energy-intensive. It has therefore already been proposed to improve it. WO 2018 / 020219 A1 discloses another process for drying wet, fiber-based blanks. Here, too, the blanks are containers. Here, the wet pulp is also pressed together inside the mold using a flexible balloon. The pre-processed container is then demolded together with the balloon inside and placed on a conveyor belt. The balloon is removed from the cold-formed container. The container is then exposed to microwaves to dry it. Before drying, the blank is very sensitive to the effects of force and must be handled very carefully.During the drying process, the container may become deformed, for example due to uneven drying or a non-uniform layer thickness, or it may be damaged by external influences.

[0006] The object of the invention is to remedy at least one of the disadvantages of the prior art. In particular, a device and a method are to be provided that make it possible to dry wet fiber-based blanks, in particular containers such as bottles, cups, bowls or trays, or wet fiber-based closure elements, with low energy consumption while ensuring that they retain their dimensionally stable.

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

[0008] A device according to the invention is provided by a compression mold for receiving a fiber-based blank. The fiber-based blank can in particular be a container or a fiber-based closure element for a container. The compression mold is intended for use in a microwave chamber. For this purpose, the compression mold is microwave-permeable. When the compression mold is closed, at least one gap is formed within the compression mold through which moisture can escape. By providing a microwave-permeable compression mold for the fiber-based blank, a wet fiber-based blank can remain within the mold during the drying process, i.e. during exposure to microwaves. The blank is thus protected against external influences and damage or deformation is prevented.By placing the wet fiber-based blank inside the microwave-transparent mold, it can also be achieved that it is accessible to 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%.

[0009] In the present process, the wet fiber-based blanks are typically formed as already known in the art. In other words, pulp is introduced into a porous mold or into a solid mold with water-draining channels whose entrances are covered with sieves 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 blank 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 press mold and thus made available in the press 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 in a dimensionally stable manner.

[0010] 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. After insertion, the mold is closed. 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.

[0011] 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.

[0012] 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%.

[0013] The at least one gap on the press form enables the displaced moisture, which in this case is essentially water, to escape from the press form.

[0014] Accordingly, it is not necessary to make the mold permeable to water. This allows the mold surfaces to be manufactured with a higher quality, while also eliminating the need for laborious cleaning of any pores or channels in the mold after use.

[0015] Moisture can also be specifically removed through a gap, or the areas in which the moisture is removed can be specifically selected.

[0016] The gap also allows moisture to be removed in a later step, namely during microwave exposure. However, in this step, the moisture is typically present as vapor.

[0017] A gap in the sense of the present description is an opening with an elongated extension. In other words, the opening has a length whose dimension is several times greater than the width dimension, in particular more than twenty times. A gap is also always arranged such that moisture can escape from the interior of the mold, i.e. from a cavity, to the outside. In other words, the gap is an opening that provides a passage arranged radially with respect to a longitudinal axis of the mold.

[0018] It can be provided that the at least one gap is formed in a region of the mold that corresponds to a region on the fiber-based blank that is removed before use of a product made from the fiber-based blank. In this case, it can be provided to arrange additional gaps on the mold.

[0019] Under certain circumstances, the gap may leave machining marks on the surface of the blank. If the gap is formed in an area that will later be separated from the blank, this circumstance is irrelevant. Any changes to the surface will therefore not be visible on the finished product, as these areas will be separated accordingly.

[0020] In particular, it can be provided that the at least one gap is formed in a region of the press mold which corresponds to a neck of the blank.

[0021] The neck of the blank can be selected to be correspondingly longer in relation to the finished product, allowing the protruding area to be easily separated. As already explained, the press mold can be constructed in two or more parts. Accordingly, it has one or more mold parting planes. Provision can be made for the gap to be formed on at least one of the mold parting planes. This can be an alternative to, or in addition to, a gap in an area that is later separated from the blank, as described here.

[0022] Forming the gap at a mold parting line allows for simple production, as the mold parting line is easily accessible with tools during production. Furthermore, a gap at the mold parting line can be cleaned easily and cost-effectively.

[0023] If the parting line of the press mold extends over the same area as a corresponding parting line of a casting mold, any defects that arise in the blank after casting can be absorbed in the press mold at the same location. This prevents unnecessary stress on the blank.

[0024] In particular, it may be provided to divide the gap between both elements of the mold parting line. In other words, in the case of a two-part mold, half of it is divided between each part of the mold. However, it would also be possible and conceivable to provide the gap only in one of the two mold halves.

[0025] In other words, the mold halves do not touch in the area of ​​the cavity, i.e. on the inner wall of the cavity, but are separated by the gap. This gap can widen outwards in a radial direction and form a channel, which narrows again with increasing radial distance from a center of the mold. The two mold halves then lie on top of one another so that the channel is closed. When the mold is completely closed, the mold parting plane towards the interior of the mold forms the gap. Preferably, the at least one gap is formed circumferentially along the entire mold parting plane.

[0026] This enlarges the opening cross-section through which the moisture can escape. Furthermore, by arranging the gap along the entire mold parting line, the entire blank is accessible from essentially all sides. This is also advantageous because a visible mark will be created in this area of ​​the product due to the casting process. By arranging the gap in the same location, an additional machining mark can be prevented.

[0027] It is conceivable that the press mold is formed in two parts in the region of a container body and additionally has a separate one-piece shoulder region and / or a separate one-piece bottom region.

[0028] As already explained, the at least one gap can open into a moisture-dissipating channel arranged within a wall of the mold. In other words, the gap can expand and expand / enlarge toward the mold, forming a corresponding channel. The moisture can be dissipated within this moisture-dissipating channel.

[0029] By providing a channel, it can be ensured that even larger amounts of moisture can be removed without causing a build-up in the gap area. A corresponding channel also makes it possible to create a forced flow to remove the moisture.

[0030] The at least one gap can have a width of 0.04 mm to 0.1 mm, in particular up to 0.4 mm. The preferred width is from 0.6 mm to 0.25 mm. These values ​​are, on the one hand, large enough to allow a corresponding amount of moisture to be removed, and, on the other hand, small enough that no marks are left on the fiber-based blank.

[0031] The length of the gap is many times greater, preferably at least 20 times, more preferably 100 times, than its width; in particular, the gap extends with its length along the press mold over at least 25% of the inner contour in preferably axial direction, i.e. in the direction of the longitudinal axis of the press mold or of the fiber-based blank formed therein.

[0032] In this case, additional openings or gaps may be provided in or on the mold to vent moisture. In particular, with certain blank geometries, it may be necessary or advantageous to vent moisture at other critical points in addition to a gap at the mold parting line.

[0033] The moisture-removing channel can be connected to a device for generating negative or positive pressure, so that a specific flow can be created in the moisture-removing channel. This allows the moisture to be removed more quickly and effectively.

[0034] Additionally, the flow in this channel can be tempered and / or dried. If an appropriate temperature, for example, an elevated temperature, is maintained in the channel, steam can be prevented from condensing as moisture in the form of water in the channel.

[0035] Openings, holes, or channels that directly connect to the outside can be incorporated into the moisture-wicking channel, allowing moisture to be removed more quickly. In addition, such channels also allow moisture to be removed at specific points along the moisture-wicking channel, thus forcing moisture removal in preferred areas.

[0036] The mold can have a substantially uniform wall thickness. This ensures that the blank in the mold is exposed to microwaves essentially evenly, and that these microwaves act accordingly evenly on the blank.

[0037] Support elements can also be provided on the mold to support the mold. Typically, a mold as described here is relatively thin-walled and / or made of at least partially elastic materials. Deformation of the mold can be prevented by appropriate support elements.

[0038] 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.

[0039] A method according to the invention for reducing the water content in a fiber-based blank, in particular in a fiber-based container or a fiber-based closure element for a container, comprises the steps:

[0040] - Providing a wet fiber-based blank in a press mold, in particular in a press mold as described herein,

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

[0042] - Expanding the expandable tool so that moisture displaced by the expansion is discharged through at least one gap on the press form.

[0043] This allows the targeted removal of moisture from the

[0044] Blank and accordingly the reduction of the moisture content of the blank so that it has a residual moisture content of less than 15%, in particular between 6% and 12%.

[0045] The fiber-based blank is preferably provided in a microwave-transparent mold.

[0046] The wet fiber-based blank is preferably exposed to microwaves after being placed in the press mold.

[0047] It can be provided that the expandable tool remains in the expanded state during the application of microwaves.

[0048] 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.

[0049] In particular , the blank is exposed to microwaves when the expandable tool is pressurized and expanded .

[0050] By applying microwaves, the moisture contained in the fibers can be converted into a vapor phase, allowing it to escape from the fibers. This vapor or gas phase is preferably removed through the at least one gap.

[0051] The moisture can be removed by forced airflow. Forced airflow can accelerate the removal of moisture.

[0052] The forced flow allows the moisture to be removed, particularly from the microwave chamber. Additionally or alternatively, a moisture-removing channel can be provided in the mold, into which the at least one gap opens. The flow in this moisture-removing channel can be generated by negative or positive pressure. Transporting the moisture into a moisture-removing channel can reliably prevent moisture from accumulating at the gap.

[0053] A region of the blank at which at least one gap of the press mold opens can be separated from the blank after reducing the water content or moisture. Accordingly, any resulting marks can be removed from the finished product, resulting in a uniform surface.

[0054] Openings, or holes or channels, that have a direct connection to the outside can lead into the moisture-draining channel, allowing moisture to be removed more quickly. In addition, corresponding openings also allow moisture to be removed at specific points along the moisture-draining channel, so that moisture removal can be accelerated in preferred areas. The channel can be formed in the area of ​​a parting plane, as described here.

[0055] The fiber-based blank can be placed in a microwave-reflecting microwave chamber before exposure to microwaves, in particular together with the press mold.

[0056] The effect of the microwaves can be increased in this way. Microwaves that are not directly absorbed by the wet fiber-based blank are typically reflected on the inner wall of the microwave chamber, thus increasing the probability that these microwaves will also reach the blank to be dried. It is generally known that excitation with microwaves can cause molecules to vibrate, and that this vibration generates heat. Water, for example, has a natural frequency of 2.45 GHz. The microwaves are therefore preferably generated at this frequency. In order to remove the water or residual moisture from the wet fiber-based blank, the water is preferably excited and thus heated until it evaporates and accordingly diffuses out of the wet blank.

[0057] In order to accelerate the drying process, the mold and / or the microwave chamber may be preheated to a temperature higher than 60 °C but preferably lower than 160 °C.

[0058] This also prevents moisture escaping from the wet fiber-based blank, particularly through a gap in the mold, from condensing again in the immediate vicinity of the blank, for example, inside the microwave chamber, and precipitating as droplets. Such precipitation leads to a reduction in efficiency, as this precipitate is continuously reheated by the applied energy.

[0059] Heating or preheating the mold and / or the microwave chamber 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.

[0060] An additional or alternative possibility to preheat the press mould could, for example, also be achieved by deliberate, partial absorption of the microwave radiation in the press mould 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 mould.

[0061] 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.

[0062] If the press mold is provided with a moisture-removing channel, the forced air flow can also develop in this channel additionally or alternatively.

[0063] 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 or at least reduced.

[0064] In order to improve the drying and / or evaporation of moisture from the wet fiber-based blank, it may also be provided to rotate it during exposure to microwaves.

[0065] The energy input into the wet fiber-based blank is thus more uniform and overheating of individual parts of the blank can be avoided.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] Such an arrangement also has a positive effect in terms of a uniform energy input.

[0072] Another way to improve quality is to apply the microwaves in a timed manner depending on the water content of the wet fiber-based blank. The timed process allows the power to be reduced. Typically, towards 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. The press mold can be porous or solid, with water-draining channels, or made of a fine-mesh material.

[0073] The method and the press mold, as described here, are preferably used in combination with a device for reducing the water content in a fiber-based blank, in particular for reducing the water content in a fiber-based blank as described here. The device has a microwave chamber for introducing a wet fiber-based container and at least one device for generating microwaves. The device also has a device for supplying and removing media from the microwave chamber. In particular, this involves the supply and removal of compressed air and moisture.

[0074] One or more devices for supplying and removing media can be arranged in such a way that, when used according to the invention, they are connected to the moisture-removing channel of the press mold.

[0075] By means of such supply and removal devices, it is possible to generate a specific air flow within the microwave chamber, with which moisture which is generated by exposure to microwaves and penetrates into the microwave chamber or possibly penetrates into the moisture-removing channel can be removed.

[0076] The device for generating microwaves can be connected to the microwave chamber by means of a waveguide.

[0077] This connection allows the device for generating microwaves to be arranged at a spatial distance from the microwave chamber and allows the microwave radiation generated by this device to be introduced into the microwave chamber in a targeted manner.

[0078] The waveguide preferably has a rectangular cross-section, with its longer side typically aligned along a longitudinal axis of the microwave chamber. The longitudinal axis of the microwave chamber essentially corresponds to the longitudinal axis of the fiber-based blank or container. This is determined by a connection between a base of the blank and a pouring opening of the blank or container.

[0079] It may be provided to provide a stirrer within the microwave chamber, in particular at the transition between the waveguide and the microwave chamber, and to swirl the microwaves with this.

[0080] Additionally or alternatively, openings can be provided along the waveguide, connecting to the microwave chamber and allowing the microwaves to propagate into the microwave chamber. This allows for a reduced size of the entire unit.

[0081] The device may have a lid for closing the microwave chamber. In this case, an exhaust air opening may be arranged in the lid. This opening thus corresponds to a device for supplying and removing a medium from the microwave chamber, in particular compressed air and moisture.

[0082] A lid allows for easy closure of the microwave chamber and precise alignment of the exhaust air opening so that a targeted air flow can be generated within the device, i.e. within the microwave chamber.

[0083] It may be possible to provide multiple exhaust air openings. This increases capacity and allows for multiple airflows.

[0084] Additionally or alternatively, the microwave chamber can be divided so that the microwave chamber consists of two identical housing parts or of housing parts of different sizes and shapes. In this case, it can be provided that each mold half is assigned to each half of the microwave chamber. For example, each mold half can be connected to a corresponding half of the microwave chamber.

[0085] The microwave chamber may additionally or alternatively have a floor. A plurality of openings are arranged in the floor for supplying air to the microwave chamber. These openings thus correspond to a device for supplying and removing a medium from the microwave chamber, in particular compressed air and moisture.

[0086] Such openings can also be formed as an integral part of the mold. In this case, the bottom of the microwave chamber can simultaneously form part of the mold, in particular a bottom of the mold. This bottom of the mold preferably ends in a microwave-tight tube. This tube prevents microwaves from escaping from the microwave chamber, while simultaneously allowing the removal of moisture and / or the supply of compressed air to create a forced flow.

[0087] The device for reducing the water content in a fiber-based container may comprise a plurality of microwave generating devices. Each of the plurality of microwave generating devices may be connected to the microwave chamber via a waveguide.

[0088] The individual microwave-generating devices can thus introduce their generated microwave radiation into the microwave chamber at different locations. At the same time, each of the devices can be controlled separately and emit microwave radiation at a different power level. The blank can be dried in a targeted manner, with different power levels being applied to it at different locations if necessary, so that the drying process is uniform overall. Uniform in this case means that the wet fiber-based container reaches a predefined water content, which is achieved simultaneously across the entire container.

[0089] For this purpose, it can be provided that the waveguides are arranged at different angles, and / or along the longitudinal axis at different heights and / or in relation to the longitudinal axis with different orientations of the longer side of the respective rectangular cross-section of the waveguide.

[0090] The device preferably comprises a holding device for the microwave-transparent mold. The microwave-transparent mold can thus be arranged and / or supported within the device, in particular within the microwave chamber.

[0091] It may be possible to apply microwaves to several blanks simultaneously. For this purpose, the device may be provided with several holding devices to hold several molds in the microwave chamber simultaneously. This reduces cycle time and enables more efficient use of the microwaves.

[0092] The holding devices can each be designed to rotate around their own axis and / or around a common axis. This allows for more efficient use of the microwaves and enables a more uniform energy input into the blanks.

[0093] Alternatively, it would also be conceivable to provide a holding device that can hold several molds simultaneously or a multiple mold. This simplifies the device, since each mold does not have to be manipulated individually when it is in the microwave chamber.

[0094] The holding device can also be designed in such a way that it is in operative connection with corresponding support elements on the press form, so that the press form is evenly supported and is not deformed.

[0095] A blank can be designed as a container, in particular as a bottle, bowl, cup, (coffee) capsule, tray, or can. Furthermore, it is possible to produce closures for containers using the method and device according to the invention.

[0096] Using schematic figures, the press mold and the process for reducing the water content in a wet fiber-based blank, along with a corresponding device, are explained. It shows:

[0097] Figure 1: A device with a press mold before exposure to microwaves;

[0098] Figure 2: the device according to Figure 1 during exposure to microwaves;

[0099] Figure 3: a perspective view of a press mold in an alternative device;

[0100] Figure 4: a sectional view through a press mold;

[0101] Figure 5 : a perspective view of an alternative

[0102] Press form;

[0103] Figure 6 : a perspective view of an alternative

[0104] Press form;

[0105] Figure 7 : a perspective view of an alternative

[0106] Press form;

[0107] Figure 8 shows, by way of example, further typical fiber-based containers that can be produced by means of the method according to the invention; Figure 9 shows, by way of example, a typical fiber-based closure that can be produced by means of the method according to the invention.

[0108] Figure 1 shows a device 200 for reducing the water content in a fiber-based blank prior to exposure to microwaves. The fiber-based blank is a container 100 in the form of a bottle.

[0109] The device 200 has a microwave chamber 40 closed by a lid 41. An exhaust air opening 42 is located in the lid 41 through which compressed air and / or moisture, such as water or steam, can be discharged. The microwave chamber 40 also has a floor 43.

[0110] A plurality of openings 44 are arranged in the floor, through which supply air can be introduced into the microwave chamber 40. The device 200 also has a device 50 for generating microwaves. This is embodied here 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.

[0111] In the device 200, a mold 20 is arranged within the microwave chamber 40. A wet fiber-based container 100 is arranged within the mold 20. This container 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 container 100 was introduced into the mold 20, an expandable tool 30 was introduced into the interior of the wet fiber-based container 100.

[0112] By expanding the expandable tool 30, the wall of the container 100 is pressed onto the inner wall of the press mold 20 and the water or moisture contained in the wet fiber-based container 100 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; in this case, individual channels or openings in the form of a gap are provided in the press mold. The water can thus be drained off through gaps or openings at the separation point of the press mold. The escaping water or moisture is represented stylized in the illustration according to Figure 1 by water droplets. 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%.

[0113] Figure 2 shows the device according to Figure 1 during the exposure of the wet fiber-based container 100 to microwaves. Figure 2 therefore shows the actual drying process. In the device 50 for generating microwaves, microwaves are generated accordingly, which are introduced into the microwave chamber 40 through the waveguide 51. The microwaves heat up the moisture located in the fiber-based container 100; in other words, the molecules begin to vibrate. The moisture begins to evaporate and exits the container 100 through the microwave-permeable mold 20. In Figure 2, 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 discharged from the microwave chamber 40. If the compression mold is provided with a moisture-dissipating channel into which the gap opens, the moisture does not escape from the compression 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 compression mold 20 to the outside of the microwave chamber 40. Such designs are explained below.

[0114] In the present case, a holding device for the microwave-transparent mold 20 is formed as an integral component of the lid 41. However, it is also conceivable for the device 200 to be formed in two parts, i.e., consisting of two halves and, if appropriate, a separate base. In this case, the mold 20 can, for example, be held and pressed together by corresponding elements on the respective halves of the device 200. A corresponding design is shown in Figure 3.

[0115] Figure 3 shows a perspective view of a compression mold 20 in an alternative device 200. A compression mold 20 is arranged within the device 200. The compression mold 20 is formed in three parts. Shown is a first half of the compression mold 20A, which is connected at a mold parting plane T to a second half of the compression mold 20B (see Figure 4), not shown here. A base part 24 is arranged in the lower region of the compression mold 20, which has a mold parting plane to both compression mold halves 20A and 20B of the compression mold 20.

[0116] The device 200 has, analogously to Figure 1, a microwave chamber 40 which is closed with a lid 41. The upper end of the compression mold 20 extends through the lid 41. The bottom 24 of the compression mold 20 also forms the bottom closure of the microwave chamber 40. The bottom part 24 merges into a microwave-tight tube 25. Figure 3 shows the mold parting plane on the compression mold half 20A with a moisture-removing channel 22 arranged therein, which opens into a gap 21 (see Figure 4) not designated in more detail here.

[0117] Several openings 23 lead into the moisture-removing channel 22, through which the moisture collected in the channel 22 can be removed. Alternatively, the channel 22 can also be pressurized through these openings 23.

[0118] In the area of ​​the mold parting line between the base 24 and the mold halves 20A and 20B, openings 23 can also be seen in the base 24. The openings 23 also open into a moisture-removing channel 22 which is arranged in the area of ​​the mold parting line between the base part 24 and the mold halves 20A and 20B in the base part 24. The channel 22 is arranged circumferentially in the base part 24. The channel 22 in the mold half 20A is also designed to run along the entire mold parting line and opens into a corresponding gap.

[0119] Moisture can also be removed through the openings 23 in the base 24 and / or the channel 22 can be pressurized.

[0120] Figure 4 shows a detail of a sectional view through the press mold 20 from Figure 3. The sectional view extends parallel to the mold parting plane between the base 24 and the press mold halves 20A and 20B (see Figure 3). The figure shows and illustrates the two press mold halves 20A and 20B which lie against one another along the mold parting plane T. It can be seen that the two press mold halves 20A and 20B form a cavity for receiving a corresponding blank. It can be seen that a gap 21 is formed at the mold parting plane in the region of the cavity, which gap opens into a moisture-dissipating channel 22 in the direction into the press mold 20, i.e. into a wall of the press mold 20. Both the gap 21 and the channel 22 are formed in half in the mold halves 20A and 20B.In other words, the interior of the mold, i.e., the cavity, is connected to the channel 22 in a radially outward direction through the gap 21. In the closed state, the mold halves 20A and 20B lie closely against each other in the same direction behind the channel 22.

[0121] Figures 5, 6 and 7 each show a perspective view of an alternative mold 20. All molds 20 have two mold halves 20A and 20B (not shown) and a base 24. In all embodiments, the base 24 opens into a microwave-tight tube 25. The base 24 is identical to the base 24 described in relation to Figure 3. In the embodiment according to Figure 5, the moisture-removing channel 22 in the mold half 20A has no further openings. In the embodiment according to Figure 6, the moisture-removing channel 22 has openings 23 in an upper region. These correspond to the openings 23 described in relation to Figure 3. The embodiment according to Figure 6 corresponds to that according to Figure 3. The embodiment according to Figure 7 corresponds in relation to the moisture-dissipating channel

[0122] 22 of the embodiment according to Figure 5. Thus, no further openings are provided in the channel 22. However, in an upper region of the mold 20, in this case in a neck region, additional gaps 21 are provided, which open directly into the cavity of the mold 20. However, these gaps are arranged in a region of the mold that corresponds to a region of the blank that is separated from the blank after the water content has been reduced. It is understood that the embodiment according to Figure 7 can also be combined with the embodiment according to Figure 6.

[0123] Figure 8 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.

[0124] Figure 9 shows an example of a typical fiber-based closure 300 that can be manufactured using the method described herein.

Claims

Patent claims 1. Press mold (20) for receiving a fiber-based blank, in particular a container (100, 100' , 100'' ) or a fiber-based closure element (300) for a container (100) , for use in a microwave chamber (40) , wherein the press mold (20) is microwave-permeable, characterized in that at least one gap (21) is formed on the press mold (20) in the closed state of the press mold (20) through which moisture can escape.

2. Press mold (20) according to claim 1, characterized in that the at least one gap (21) is formed in an area of ​​the press mold (20) which corresponds to an area on the fiber-based blank that is removed before the use of a product produced from the fiber-based blank.

3. Press mold (20) according to claim 2, characterized in that the at least one gap (21) is formed in an area of ​​the press mold (20) which corresponds to a neck of the blank.

4. Press mold (20) according to one of claims 1 to 3, characterized in that it is formed in multiple parts and accordingly has one or more mold parting planes (T), wherein the at least one gap (21) or an additional gap (21) is formed on at least one of the mold parting planes (T).

5. Press mold according to claim 4, characterized in that the at least one gap (21) is formed circumferentially along the entire mold parting line (21).

6. Press mold (20) according to one of claims 1 to 5, characterized in that the at least one gap (21) is in a A moisture-draining channel (22) opens into a wall of the mold (20). A mold (20) according to any one of claims 1 to 6, characterized in that the at least one gap (21) has a width of 0.04 mm to 0.1 mm. A mold (20) according to any one of claims 1 to 7, characterized in that additional openings are provided in the mold (20) for moisture drainage. A mold (20) according to any one of claims 6 to 8, characterized in that the moisture-draining channel (22) is connected to a device for generating a vacuum or a positive pressure, so that a specific flow can be created in the moisture-draining channel (22). A mold (20) according to any one of claims 1 to 9, characterized in that the mold has a substantially uniform wall thickness.A press mold (20) according to one of claims 1 to 10, characterized in that support elements are provided on the press mold (20) to support the press mold (20). A method for reducing the water content in a fiber-based blank, in particular in a container (100, 100', 100'') or a fiber-based closure element (300) for a container (100), comprising the steps. - Providing a wet fiber-based blank in a press mold, in particular in a press mold according to any one of claims 1 to 11, - Insertion of an expandable tool (30) into the wet fiber-based blank, - Expanding the expandable tool (30) , characterized in that the material displaced by the expansion Moisture is drained away through at least one gap (20) in the press mold. Method according to claim 12, characterized in that the wet fiber-based blank is subjected to microwaves after being placed in the press mold (20). Method according to claim 13, characterized in that any moisture remaining in the blank is converted into a gaseous phase by the microwaves, and this phase is drained away through the at least one gap (20). Method according to any one of claims 12 to 14, characterized in that the moisture is drained away by a forced flow. Method according to claim 15, characterized in that a moisture-draining channel (22) is provided in the press mold, into which the at least one gap opens, wherein the flow in this moisture-draining channel (22) is generated by negative pressure or positive pressure.Method according to one of claims 12 to 16, characterized in that an area of ​​the blank, at which the at least one gap (21) of the press mold (20) opens, is separated from the blank after reducing the water content.

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