Method and system for introducing moisture into molded fiber packaging units in manufacturing process

Abstract

The invention relates to a method and a system for introducing moisture into a molded fiber packaging unit in a manufacturing process. The method comprises the following steps: preparing a moldable fibrous material; -shaping the moldable fibrous material in a mould into a primary packaging unit having compartments; -providing a humidified stream to the primary packaging unit and forcing said stream through the fibrous material of the primary packaging unit; and-controlling the humidification flow as a function of the permeability of the primary packaging unit.

Description

Technical Field

[0001] This invention relates to a method for manufacturing molded fiber packaging units, and more specifically to introducing moisture into such packaging units. These packaging units are made from molding slurry materials and are typically used to contain, store, transport, cover, and / or display a range of products, such as food products including beverages. The packaging units can specifically relate to containers, cups, holders, lids, dishes, siplids, boxes, trays, etc. Molded fiber packaging units can be manufactured using a wet molding process using a slurry matrix (optionally involving a foamed slurry matrix) and / or using a dry-laid process using a "fluffy" slurry matrix. Background Technology

[0002] The conventional manufacturing process for molded fiber products involves the preparation of moldable fiber material, which is then typically molded in a mold to provide primary packaging units. These primary packaging units have a non-homogeneous / uncontrolled moisture content or distribution within the packaging unit, and / or relatively large variations in moisture content between individual packaging units. This (uncontrolled) variation in moisture content affects product characteristics; for example, the effects achieved through the (post-molding) pressing step depend on the moisture content and / or moisture distribution. This leads to variations in the product quality of these products.

[0003] WO 2020 / 223943 A1, DE 692 21 442T2 and US2 938 582 A disclose conventional methods for manufacturing molded fiber packaging units.

[0004] Typically, primary packaging units are stored under controlled conditions to ensure uniform moisture content. This controlled storage reduces variations in moisture content within and / or between different packaging units, thereby minimizing negative impacts on product characteristics.

[0005] These conventional storage processes are very time-consuming and require product buffering. This process step increases manufacturing costs. Furthermore, the risk of heterogeneous / uncontrolled moisture distribution / variation between and / or within different products remains relatively high, potentially leading to changes in product characteristics / quality. Summary of the Invention

[0006] The object of the present invention is to eliminate or at least reduce one or more of the aforementioned problems in the conventional manufacturing process of molded fiber packaging units, and to provide a manufacturing method that is both cost-effective and provides high-quality packaging units.

[0007] Therefore, the present invention provides a method for manufacturing a molded fiber packaging unit, the method comprising the following steps:

[0008] -Preparation of moldable fiber materials;

[0009] - Molding moldable fiber material into primary packaging units with compartments in a mold;

[0010] - Provide a humidifying flow to the primary packaging unit and force the flow through the fibrous material of the primary packaging unit; and

[0011] - Control the humidification flow based on the permeability of the primary packaging unit.

[0012] The molded fiber packaging unit manufactured according to the method of the invention can be produced by a wet molding process using a slurry matrix and / or a dry-laying process using a “loose” slurry matrix. In the wet molding process, the slurry matrix is ​​provided to a mold, and the product is dried after molding. Optionally, this may involve a foaming step to provide a foaming material for molding. Alternatively, in the dry-laying process, the slurry matrix can be supplied in sheets or rolls, which can be fed into a hammer mill or similar device (also known as a fiber separator) that separates the compressed slurry rolls or sheets into individual loose fibers, which are then conveyed to the molding system that forms the molded fiber packaging unit.

[0013] The preparation and provision of moldable fibrous materials typically involves providing a quantity of fibrous material. This fibrous material can have various sources, such as wood and / or non-wood fibrous materials, optionally derived from recycling processes, such as recycled paper materials. Alternatively, or in addition to such paper materials, the fibrous material may also include a quantity of non-wood fibrous materials, also referred to as natural fibers and / or alternative fibers. Such fibers may involve biomass fibers from plant sources, examples of which are described in WO 2021 / 145764A1. After the preparation of the moldable fibrous material, a primary packaging unit is formed in a mold. This molding involves shaping the material into the desired shape of the primary packaging unit, which typically has compartments capable of carrying or holding a product (e.g., food containing beverages). After the molding process, the primary packaging unit is typically dried, optionally involving an in-mold drying step.

[0014] According to the invention, a humidifying flow, such as a humidifying airflow, and more specifically, a supersaturated humidifying airflow (“mist”), is provided to the primary packaging unit. This humidifying flow forces the moisture content within the primary packaging unit to regulate it, and also homogenizes it. Preferably, the moisture content in a batch of primary packaging units is also homogenized, such that variations / distributions in moisture content are significantly reduced, better regulated, and more or less constant over time within a batch of products. Alternative methods of providing moisture to the primary packaging unit include spraying, brushing, and printing. These methods can be applied as alternatives or in combination with each other and / or in conjunction with providing a supersaturated humidifying airflow. Experiments have shown that providing a supersaturated humidifying airflow can effectively regulate specific moisture contents.

[0015] For example, for a small cup weighing approximately 1.25 g, it is generally desirable to increase the total moisture content by about 0.1 g / cup and to distribute the moisture evenly across the cup. The total moisture content can vary and can range from 5 wt% to 10 wt% of the total product weight. It should be understood that the desired moisture content level can depend on product characteristics, material properties, intended use, etc. The temperature of the humidifying gas flow is typically in the range of 20°C to 70°C. In some embodiments according to the invention, the temperature of the humidifying gas flow is substantially similar to the temperature of the process equipment to minimize the temperature difference between the flow and the equipment. It should be understood that both temperature and flow rate can vary depending on the specific circumstances.

[0016] According to the present invention, the manufacturing method further includes the step of controlling the aforementioned humidification flow based on the permeability of the primary packaging unit. The permeability of the primary packaging unit is (primarily) defined by the fibers. The influence of "free" moisture inside the primary packaging unit is minimal or non-existent. Generally, the permeability of a product is the ability of the porous material of the product to transport fluids, wherein the product has a certain cross-section and thickness and is affected by pressure (or pressure differential). Air permeability is generally defined as a measure of the ability of air to pass through a material, measured by the volume of air passing through a specific cross-section of the material at a specific pressure differential over a time interval.

[0017] Controlling the humidification flow based on the permeability of the primary packaging unit has proven to significantly contribute to the regulation (preferably homogenization) of moisture content within a single primary packaging unit and between different primary packaging units. Tests have shown that the properties / characteristics of the final product are significantly more consistent for packaging units manufactured using the method according to the invention compared to conventional manufacturing processes.

[0018] Preferably, in one of the presently preferred embodiments of the invention, the method further includes the step of providing an additive to the humidifying flow. Such additives may involve applying one or more additives to alter surface tension and / or viscosity, change the size of water droplets in the flow, and / or the interaction between moisture and the fibers of the packaging unit. Furthermore, the additives may involve colorants and barrier additives. The additives may be provided as dissolved or suspended additives. Testing has shown that adding one or more additives to the humidifying flow is an effective method for altering the behavior of the humidifying flow and / or coloring the packaging unit and / or improving barrier performance.

[0019] It should be understood that, in addition to the manufacturing steps described above, other steps may be performed. For example, the laminate may be attached to the packaging unit, and other pressing steps may be performed to improve product characteristics.

[0020] Preferably, controlling the humidification flow involves directly or indirectly considering the permeability of the primary packaging unit. The controller guiding the humidification flow through the primary packaging unit is provided with information about permeability, directly or indirectly. This may involve measuring the permeability of the primary packaging unit and / or measuring the variation in permeability between different primary packaging units. If the permeability of the primary packaging unit differs from expectations, the humidification flow settings can be adjusted accordingly by the controller. For example, in cases of relatively low permeability, the flow resistance is relatively high, making it more difficult for the humidification flow to force itself through the fibrous material of the primary packaging unit. The controller can then adjust the humidification flow settings, for example, by changing one or more pressures in the process.

[0021] In a presently preferred embodiment of the invention, the method further includes the step of providing a pressure differential on the primary packaging unit.

[0022] The amount (flow rate) of humidification flow provided by the fibrous material through the primary packaging unit depends on the pressure differential across the fibrous material. Manipulating the pressure on one or both sides of the primary packaging unit can change the pressure differential, thereby affecting the humidification flow through the fibrous material of the primary packaging unit. This allows the primary packaging unit to control the amount of moisture absorbed, resulting in more consistent overall product characteristics of the final product. In the tests using the aforementioned small cups, a pressure differential of approximately 700 mbar was applied to the primary packaging unit, preferably in the range of 350 mbar to 900 mbar, more preferably in the range of 450 mbar to 800 mbar, and most preferably approximately 700 mbar.

[0023] In a presently preferred embodiment of the invention, providing the humidifying flow includes directing the humidifying flow to a first side of the primary packaging unit and further includes providing a negative pressure at a second side of the primary packaging unit, such that the humidifying flow is forced through the primary packaging unit from the first side to the second side. In this embodiment, the first side of the primary packaging unit is upstream of the humidifying flow relative to the primary packaging unit, while the second side of the primary packaging unit is downstream of the humidifying flow relative to the primary packaging unit. The pressure difference between the first upstream side and the second downstream side of the primary packaging unit is related to the flow rate of the humidifying flow through the primary packaging unit, and therefore to its moisture absorption and / or moisture homogenization.

[0024] In a currently preferred embodiment of the invention, the controller guides the pressure on another second side of the primary packaging unit.

[0025] Controlling and, where necessary, adjusting the pressure on the downstream second side of the primary packaging unit has proven to be an effective means of introducing moisture into the molded fiber packaging unit (more specifically, the primary packaging unit) and / or homogenizing its moisture content. Preferably, the controller controls the negative pressure on the second side of the primary packaging unit, wherein the negative pressure is typically below 1.0 bar, thereby controlling the humidification flow and moisture absorption / homogenization.

[0026] In another preferred embodiment of the invention, the method includes the step of measuring the pressure difference on the primary packaging unit.

[0027] Measuring the pressure differential across the primary packaging unit provides direct information about its permeability. Therefore, the controller can adjust process settings to manipulate the humidification flow, resulting in more uniform product characteristics, independent of the actual permeability of the primary packaging unit. This pressure differential is typically measured by a sensor or sensor system that provides the measurement results to the controller.

[0028] In another preferred embodiment of the invention, the method further includes the step of providing a humidifying flow to the primary packaging unit at time intervals ranging from 10 milliseconds to 60 seconds, preferably from 2.0 seconds to 20 seconds, and most preferably from 3.0 seconds to 10 seconds.

[0029] Tests have shown that providing and / or maintaining a humidifying flow to the primary packaging unit at one of the aforementioned time intervals provides effective moisture absorption, regulation, and / or homogenization of the moisture content of the primary packaging unit. It should be understood that the actual time intervals may depend on, for example, the design and weight of the primary packaging unit.

[0030] In a currently preferred embodiment of the invention, the step of providing the humidifying flow involves providing a flow rate in the range of 2.0 l / min to 20 l / min per gram of primary packaging unit. Test results have shown that a flow rate within the above range provides effective moisture absorption, regulation, and / or homogenization of the moisture content of the primary packaging unit.

[0031] In yet another currently preferred embodiment of the invention, the method includes the step of simultaneously providing a humidifying flow to two or more primary packaging units.

[0032] Providing humidifying streams to multiple primary packaging units simultaneously, where multiple involves two or more, enables higher production capacity. In this embodiment, the humidifying streams are prepared and simultaneously supplied to two or more primary packaging units. This is preferably done in-process, meaning no separate storage or buffering steps are required. This achieves a cost-effective manufacturing process for the packaging units.

[0033] Preferably, when humidifying flows are supplied to two or more primary packaging units simultaneously, and when the humidifying flow in one of the primary packaging units is actually low, the controller preferably adjusts the pressure on the second downstream side of the primary packaging unit experiencing the lower humidifying flow. Experiments have shown that this method is advantageous for regulating the moisture content of different molded fiber packaging units. Alternatively, the back pressure of other primary packaging units (the pressure on the other second downstream side) can be adjusted accordingly.

[0034] In another preferred embodiment of the invention, the method includes the step of providing a distribution system configured to simultaneously provide humidifying flow to multiple primary packaging units.

[0035] The distribution system enables the controlled supply of humidifying flow to two or more primary packaging units simultaneously. For example, such a distribution system may involve the use of a set of pipes and / or manifolds.

[0036] The present invention also relates to a system for introducing moisture into a molded fiber packaging unit during a manufacturing process, wherein the system is configured to perform a method according to an embodiment of the invention.

[0037] This system provides the same or similar effects and advantages as described regarding the method.

[0038] The system is specifically triggered to process the primary packaging unit by providing a humidifying flow. Therefore, the system preferably includes a controller configured to at least control the supply of the humidifying flow to the primary packaging unit. Optionally, this involves applying one or more so-called pulse width modulation valves.

[0039] In a preferred embodiment of the invention, the system further includes a distribution system configured to simultaneously supply humidifying streams to two or more primary packaging units. This increases the overall production capacity of the process.

[0040] In another preferred embodiment of the invention, the system further includes a sensor system configured to determine a pressure differential across the primary packaging units. Preferably, this pressure differential is used as a measure of the permeability of the primary packaging units. Preferably, this measure is provided to a controller that directs a humidifying flow to the primary packaging units, and more preferably to two or more primary packaging units simultaneously.

[0041] The packaging unit can be manufactured from a molding slurry material using a manufacturing method and / or system according to one of the foregoing embodiments of the present invention. Therefore, the present invention also relates to packaging units made of such molding fiber materials. These packaging units can relate to containers, cups, holders, lids, caps, boxes, dishes, trays, etc. Attached Figure Description

[0042] Other advantages, features, and details of the invention are described based on preferred embodiments thereof, with reference to the accompanying drawings, wherein:

[0043] - Figure 1 A schematic diagram of the manufacturing process relating to the method of the present invention is shown;

[0044] - Figure 2 It schematically shows the ability to execute Figure 1 The method of the system components according to the embodiment of the present invention; and

[0045] - Figures 3A to 3B , Figure 4 and Figure 5 It shows that it can be used Figure 1 and / or Figure 2 Examples of molded fiber products manufactured using methods and / or systems. Detailed Implementation

[0046] Manufacturing process 2 ( Figure 1The process includes a preparation step 4, in which a slurry material 6 is prepared. This slurry material 6 is then provided to a molding step 8, in which a primary product 10 is molded. The primary product 10 is then dried in a drying step 12 to obtain a primary packaging unit 14. A moisture conditioning / homogenization step 16 for conditioning / homogenizing the moisture content of the primary packaging unit 14 involves providing a humidifying flow to the primary packaging unit 14 and producing a (homogenized) packaging unit 18 with a conditioned moisture content. This step may include providing one or more additives to the humidifying flow. The packaging unit 18 may undergo one or more post-processing processes 20, such as lamination and / or pressing processes, to produce a final product 22, which is then used in step 24.

[0047] Preparation step 4 may involve applying and / or mixing wood fiber materials and / or non-wood materials (e.g., alternative fibers). For example, wood materials may involve so-called virgin fibers and / or fibers from recycled paper materials. This produces a slurry for a wet molding process, which optionally contains a foaming agent to enable the manufacture of foamed packaging units. Alternatively, this produces a fluffy slurry matrix to enable a so-called dry-lay process for molding fiber packaging units.

[0048] System 26 can be used Figure 2 The method step 16 of providing a humidifying flow to the primary packaging unit 14 is performed. The system 26 for adjusting / homogenizing the moisture content of the molded fiber packaging unit includes a flow generating unit 28 that generates a humidifying flow 30, preferably with a supersaturated moisture content, thereby providing a “mist” to the flow distributor 32. The flow distributor 32 provides a humidifying flow 34, similar to the humidifying flow 30, to the individual primary packaging units 14. In the illustrated embodiment, the sensor system 36 measures the properties and / or other suitable conditions of the primary packaging unit 14 and / or the humidifying flow 34 to generate a measurement signal 38. The measurement signal 38 is provided to a controller 40, which generates a control signal 42 to set the flow distributor 32 and optionally generates a control signal 44 to set the flow generating unit 28.

[0049] Method 2 and system 26 can be used to manufacture a series of packaging units. As an example, cup-shaped packaging unit 102 can be manufactured ( Figures 3A-3B The container includes a cup-shaped container body 104 having a bottom 106 and sidewalls 108. Preferably, a flange or edge 110 is configured to optionally receive a seal or cap 112 thereon. The interior of the cup 102 defines a product compartment 114. Optionally, the bottom 106 includes an additional support 116. Also optionally, the inner wall 118 of the compartment 114 is provided with a laminate 120.

[0050] Small cap 202 ( Figure 4The cup includes a top wall 204 and a first wall portion 206, which, in the illustrated embodiment, connects to a second wall portion 208 having a transition region 210. The cap 202 preferably has a platform structure 212 with an opening 214. The bottom 216 of the cap 202 is open to receive liquid and supply liquid to the opening 214. This portion defines a compartment 218 in which liquid can be received so that a user can drink liquid from the cup through the opening 214 of the cap 202.

[0051] Pallet 302 ( Figure 5 The compartment 314 includes a bottom 304, a side 306, an outer side wall 308, and an inner side wall 310. In the illustrated embodiment, the bottom 304 and the inner side wall 310 are provided with a laminated layer 312. The compartment 314 is defined by the bottom 304, the side wall 310, and the side 306.

[0052] The flow distributor 32 can be configured in various embodiments, including implementations with a central (mist) generation and a delivery system using two or more pipes and / or manifolds to provide flow to two or more primary packaging units 14. Alternatively, the flow distributor 32 relates to localized (mist) generation for each individual primary packaging unit 14. It should be understood that other embodiments of the flow distributor are also conceivable according to the invention, including the application of nozzles optionally involving pulse width modulation. Different embodiments, including central “mist” generation and localized “mist” generation, have been tested. Results show that the greater the flow, the higher the moisture absorption.

[0053] In the tests, one or more pulse width modulation valves were used to illustrate the effect of the opening percentage on the added moisture (grams) for each individual product. The results showed that as the valve opening interval increased, the added moisture increased.

[0054] To illustrate the effect of permeability on moisture absorption when humidifying flows 30, 34 are supplied to the primary packaging unit 14, a moisture conditioning / homogenization step 16 is performed using controller 14. The results show that the moisture absorption (grams) of each product is constant and independent of the actual permeability of any individual product. This demonstrates the function and effectiveness of supplying humidifying flows 30, 34 to the primary packaging unit 14 during the conditioning / homogenization step 16.

[0055] This invention is by no means limited to the preferred embodiments described above. The sought rights are defined by the following claims, and many modifications may be contemplated within their scope.

Claims

1. A method for introducing moisture into a molded fiber packaging unit during a manufacturing process, the method comprising the following steps: -Preparation of moldable fiber materials; - The moldable fiber material is molded in a mold into a primary packaging unit with compartments; - Provide a humidifying flow to the primary packaging unit and force the flow through the fibrous material of the primary packaging unit; and - The humidification flow is controlled according to the permeability of the primary packaging unit.

2. The method according to claim 1, wherein, The step of providing humidification flow includes providing supersaturated humidification airflow.

3. The method according to claim 1 or 2, wherein, Controlling the humidification flow involves taking into account the permeability of the primary packaging unit, either directly or indirectly.

4. The method according to claim 1, 2 or 3, further comprising the step of providing a pressure differential over the primary packaging unit.

5. The method according to the preceding claim, wherein, Providing the humidifying flow includes directing the humidifying flow to a first side of the primary packaging unit and providing negative pressure at a second side of the primary packaging unit.

6. The method according to the preceding claim, wherein, Controlling the humidification flow includes guiding the pressure on another second side of the primary packaging unit.

7. The method according to any one of claims 4 to 6, further comprising the step of measuring the pressure difference on the primary packaging unit.

8. The method according to any one of the preceding claims, further comprising the step of maintaining the humidifying flow to the primary packaging unit at a time interval ranging from 10 milliseconds to 60 seconds, preferably from 2.0 seconds to 20 seconds, and most preferably from 3.0 seconds to 10 seconds.

9. The method according to any one of the preceding claims, wherein, The step of providing humidification flow includes providing a flow rate in the range of 2.0 l / min to 20 l / min per gram of primary packaging unit.

10. The method according to any one of the preceding claims, further comprising the step of simultaneously supplying the humidifying flow to two or more primary packaging units.

11. The method according to the preceding claim, wherein, When the humidification flow of one of the two or more primary packaging units is low, the controller adjusts the pressure on the other second side of the primary packaging unit experiencing the lower humidification flow.

12. The method according to the preceding claim, further comprising the step of providing a distribution system configured to simultaneously provide the humidifying flow to a plurality of primary packaging units.

13. The method according to any one of the preceding claims, further comprising the step of providing an additive to the humidifying flow.

14. A system for introducing moisture into a molded fiber packaging unit during a manufacturing process, wherein, The system is configured to perform the method according to any one of the preceding claims.

15. The system according to the preceding claim further includes a controller configured to at least control the supply of the humidifying flow to the primary packaging unit.

16. The system according to the preceding claim, wherein, The controller includes a pulse width modulation valve.

17. The system according to any one of claims 14 to 16, further comprising a distribution system configured to simultaneously supply the humidifying flow to two or more primary packaging units.

18. The system according to any one of claims 14 to 17, further comprising a sensor system configured to determine the pressure differential across the primary packaging unit.

Images