Method for pretreating fiber-containing material, pretreatment chamber, and fiber molding equipment

Abstract

This paper describes a method for pretreating fibrous material in a manufacturing process for producing three-dimensional products, a pretreatment chamber for pretreating fibrous material, and a fiber forming system with at least one pretreatment chamber. Pretreating relatively dry fibrous material significantly improves the shaping process and increases the range of possible product geometries.

Description

Technical area

[0001] A method for pretreating fibrous material in a manufacturing process for producing three-dimensional products, a pretreatment chamber for pretreating fibrous material and a fiber molding plant with at least one pretreatment chamber are described.

[0002] Fibrous materials are frequently used to produce packaging for food (e.g., trays, capsules, boxes, lids, etc.) and consumer goods (e.g., electronic devices, etc.), as well as beverage containers. Everyday items such as disposable cutlery and tableware are also made from fibrous materials. Fibrous materials include natural or synthetic fibers. Recently, there has been an increasing use of fibrous materials that contain natural fibers or are made from fibers that can be obtained, for example, from renewable resources or recycled paper.

[0003] Fiber-containing materials can be processed in a wet or dry state. For example, fibers can be separated and combined to form a nonwoven layer, which can then be further processed. The water content can range from 0 to 60 wt.%, for example.

[0004] Dry processing is generally referred to as a "dry fiber" processing process. The moisture content can range from 0 to 40% by weight, for example.

[0005] So-called dry-fiber processes include, for example, paper, cardboard, airlaid, compressed airlaid, and nonwoven thermoforming processes. Airlaid refers to individual fibers or fiber bundles that are drawn over a screen belt and deposited there to form a relatively loose fiber composite. In compressed airlaid, these fiber layers can then be pressed together. Alternatively, preforms with a geometry similar to the product to be manufactured can be preformed. background

[0006] However, dry-fiber thermoforming processes are subject to significant limitations in terms of formability. This is due to the material properties of natural fibers in the dry state. Depending on the fiber-containing material used, the maximum elongation is 2-5% relative to the initial state. Furthermore, fiber-containing materials exhibit poor flow behavior. This severely limits the range of possible product geometries (depth, ribs, undercuts, draft angles <10°, etc.) for products made from fiber-containing materials.

[0007] Paper, in particular, is very difficult to deform, as it tends to tear when deformed. Fluff-pulp materials (e.g., airlaid) are easier to deform than paper. However, the deformation is limited by the thickness of the layer, as flowing fibers within the material leads to undesirable thinning of the layer.

[0008] The production of products from a fibrous material is known, for example, from WO 2017 / 160218 A1. Task

[0009] The object is therefore to provide a solution for the production of three-dimensional products from a fibrous material, which eliminates the disadvantages of the prior art and provides the production of three-dimensional products from fibrous material, which is essentially not subject to any restrictions with regard to the mold depth and product geometry in the production of three-dimensional products in a "dry fiber" processing method. Solution

[0010] The above-mentioned object is achieved by a method for the pretreatment of fibrous material which has a water content of less than 30% by weight in a manufacturing process for producing three-dimensional products, wherein fibrous material is subjected to a product-specific pretreatment before at least one shaping process step of three-dimensional products and the fibrous material is then directly processed further, wherein the fibrous material is at least partially moistened during the product-specific pretreatment.

[0011] Pretreating the fibrous material, which is used as a raw material / semi-finished product for product manufacturing, enables the production of products with large mold depths, ribs, or other configurations by moistening the fibrous material in selectable areas. This previously was impossible due to the dry state of the starting material. In particular, moistening the fibrous material expands the process window.

[0012] It is important that not all of the fibrous material needs to be moistened, but rather that only those areas of the fibrous material that are subject to greater deformation (e.g., side walls of cups with draft angles > 10°) in a subsequent forming process are moistened, so that the fibrous material can be deformed more intensively in these areas. It has been shown that fibrous material with a moisture content greater than 20 wt.% exhibits better flow behavior without significantly weakening the material layer in this area. The pretreatment and moistening are product-specific, so that areas that are not subject to subsequent deformation, for example, are not moistened or are moistened to a lesser extent.

[0013] The moistening of areas of the fibrous material can be carried out differently for a product, so that correspondingly different mold depths can be achieved with the same material thickness of the finished product and the same product quality.

[0014] In designs where a material web is pretreated, products are manufactured from areas within the material web. The intermediate areas are not deformed and can subsequently be reused or disposed of. The unused areas are not moistened in the process described above.

[0015] Advantageously, pretreatment takes place directly in a manufacturing process before further processing (e.g. shaping by pressing at high pressure / temperature). This can prevent, for example, an expansion of moistened areas, whereby introduced water flows into the fibrous material. The drier the fibrous starting material, the greater the expansion of the moistened area can be. If moistening takes place immediately before shaping during a manufacturing process, the risk of damage to the fibrous material is reduced or eliminated. During a subsequent shaping process, the previously introduced moisture is expelled due to the high pressure (e.g. 500 N / cm²< specific surface pressure) and the high temperature (e.g. 150 °C - 200 °C), so that the final product has a uniform moisture content across all areas and surfaces.Therefore, no expansion of moistened areas occurs after shaping.

[0016] In further embodiments, at least one temperature, humidity, and / or steam treatment and / or additive addition to the fibrous material can be carried out during the product-specific pretreatment. The treatment can be carried out, for example, by spraying specific areas and / or targeted heating (e.g., using infrared or a heating element). Furthermore, the fibrous material can be exposed to a humid climate, for example, within a chamber, where, for example, the surface of the fibrous material is moistened and / or mixed with additives and supplements. With an optional or additional temperature treatment, the properties of the fibrous material can be improved. The improvement in the properties of the fibrous material primarily refers to properties that are crucial for a subsequent processing step, such as a molding process.In addition, the properties of the final product can also be influenced, whereby such treatment often takes place after a forming process, since deformation can, for example, lead to damage to a previously applied barrier layer.

[0017] Introducing steam into the material can also provide heating. This can, for example, reduce the temperature during a subsequent pressing step.

[0018] In further embodiments, the pretreatment may comprise at least one pretreatment step.

[0019] In further embodiments, a selective pretreatment of the fibrous material can be carried out. A selective pretreatment, which depends on the product geometry of the product to be manufactured, can, for example, involve different pretreatment of certain areas. For example, to achieve homogeneous barrier properties for a finished product, an uneven coating or pretreatment can be carried out so that the final product still has a uniform layer thickness (e.g., barrier layer) after forming. In further embodiments, areas with high moisture content (20-50%) can be coated, whereby the total moisture content of the entire area of ​​a fibrous material for a product remains below 20% to avoid steam explosions during the forming process.

[0020] In further designs, the fiber-containing material can be fed to the pretreatment in the form of separate preforms, as sheets or as a continuous web.

[0021] In further embodiments, during the selective pretreatment only areas that are to be formed in a subsequent process step can be pretreated, so that a uniform product quality and properties of a finished product can be achieved.

[0022] In further embodiments, the pretreatment can be applied to at least one side of the surface of the fibrous material. The fibrous material is generally guided through the pretreatment process in one transport direction and, for example, has a bottom side and a top side. In this case, the pretreatment can then act only on the bottom side or the top side, for example. In further embodiments, pretreatment can also be applied to both the bottom side and the top side. In other embodiments, pretreatment of a top side and a bottom side can take place alternately.

[0023] In further embodiments, the pretreatment can be carried out in several pretreatment steps, whereby different pretreatments can be carried out in the pretreatment steps, which can be coordinated in their sequence depending on the requirements or can take place in any order.

[0024] In further embodiments, the pretreatment can take place within a pretreatment chamber, in which the fiber-containing material is at least temporarily protected from external influences. Such a pretreatment can be used, for example, to carry out special pretreatments in an atmosphere (pressure, temperature, (air) humidity) that differs from the atmosphere of the manufacturing process or a manufacturing site. Appropriate means, such as movable flaps or the like, can be provided for temporarily decoupling the interior of a pretreatment chamber.

[0025] In further embodiments, different properties may prevail in at least one section of the pretreatment chamber compared to the environment of the pretreatment chamber, wherein the properties include pressure, temperature and / or humidity.

[0026] In further versions, the quality and appearance or properties of products can be tested and evaluated using additional devices (sensors, cameras, etc.). If deviations from a target value are detected, a control system can be used to directly adjust and change the pretreatment process parameters. For example, certain areas can be moistened more or less and / or the areas of the fibrous material to be moistened can be adjusted locally (e.g., by changing the orientation of nozzles, etc.). In further versions, the temperature and / or the throughput speed can also be adjusted during pretreatment.

[0027] In further embodiments, a first pretreatment can be performed before a first processing step, followed by at least a second pretreatment before at least a second processing step. For example, a pretreatment can be performed first, moistening areas of fibrous material that are then preformed. This is followed by further moistening of the areas that are finally formed in a final, second forming station. The step-by-step pretreatment or moistening thus always takes place immediately before the respective processing step or forming process, so that the properties of the fibrous material are specifically influenced for the next processing step.

[0028] The above-mentioned object is also achieved by a pretreatment chamber for the pretreatment of fibrous material which has a water content of less than 30% by weight, wherein the pretreatment chamber is part of a fiber molding plant for producing three-dimensional products, wherein a product-specific pretreatment of the fibrous material can be carried out in the pretreatment chamber, and has at least one device for pretreatment with which at least one temperature, humidity and / or steam treatment and / or an additivation of introduced fibrous material can be carried out.

[0029] Furthermore, the above-mentioned object is achieved by a fiber molding plant which has at least one pretreatment chamber according to at least one of the above embodiments, wherein the at least one pretreatment chamber is arranged in front of at least one molding station.

[0030] The above statements on pretreatment apply accordingly to a pretreatment chamber and a fiber molding plant with such a pretreatment chamber.

[0031] Further features, embodiments and advantages emerge from the following presentation of embodiments with reference to the figures. Short description of the characters

[0032] In the drawings shows: Fig. 1 shows a schematic representation of a fiber molding plant for producing three-dimensional products from a fiber-containing material; Fig. 2 shows a further schematic representation of a fiber molding plant for producing three-dimensional products from a fiber-containing material; and Fig. 3 shows a schematic representation of another fiber molding plant for producing three-dimensional products from a fiber-containing material. Detailed description of implementation examples

[0033] The following figures illustrate exemplary embodiments of the technical teaching described herein with reference to the figures. The same reference numerals are used for identical components, parts, and processes in the description of the figures. Components, parts, and processes that are not essential to the technical teaching disclosed herein or that would be obvious to a person skilled in the art are not explicitly shown. Features stated in the singular are also included in the plural, unless explicitly stated otherwise. This applies in particular to statements such as "a" or "an."

[0034] The figures show exemplary embodiments of a fiber molding system 100 with at least one pretreatment chamber 120; 140 and at least one molding station 130; 150. The exemplary embodiments shown do not represent any limitation with regard to further developments and modifications of the described embodiments. Thus, alternative embodiments to individual exemplary embodiments can also be provided alternatively or cumulatively in other exemplary embodiments.

[0035] Fig. 1shows a schematic representation of a fiber molding system for producing three-dimensional products from a fibrous material. The fiber molding system 100 can be used to produce products that are biodegradable and can themselves serve as starting materials for the production of three-dimensional products from a fibrous material. These products can generally be completely decomposed and do not contain any harmful, environmentally hazardous substances. The products can be designed, for example, as cups, lids, bowls, capsules, plates, and other shaped and / or packaging parts (e.g., as holder / support structures for electronic or other devices).

[0036] In the illustrated embodiment, a material web 200 made of a fibrous material is processed. The material web 200 contains fibers of natural origin and has a moisture content of less than 30% water by weight.

[0037] In the exemplary embodiment, the fiber molding system 100 has a feed 110. The feed 100 can, as schematically indicated, also have a transport device, which serves to transport a material web 200, web sections, or preformed preforms. The transport device can be designed in various ways. Depending on the design of a pretreatment chamber 120; 140, a transport device can also support or hold a material web 200 or other fibrous material only in certain areas in order to also enable treatment from an underside. In the embodiment shown, a material web 200 is unwound from a roll and fed endlessly in the processing direction to a first pretreatment chamber 120. The material web 200 passes through the first pretreatment chamber 120 and is subjected to three pretreatment steps (I., II., III.).During pretreatment, the properties of the material web 200 are selectively influenced in a product-specific manner to support or enable subsequent shaping. For this purpose, the material web 200 is fed to a first forming station 130 after pretreatment. In the forming station 130, areas of the material web 200 are deformed and given their final three-dimensional shape.

[0038] The material web 200 can be advanced continuously or intermittently via the feed device 110. In the illustrated embodiment, the pretreatment and shaping take place during a feed pause. To ensure continuous unwinding of the material web 200, length compensation devices can be provided, such as those known, for example, in thermoforming systems for plastic films.

[0039] The fiber molding system 100 can have additional stations and equipment. For example, a storage area for fiber-containing material can be provided. In further embodiments, a mill can be provided for comminuting a starting material and separating fibers, which can then be fed to a pretreatment stage as "airlaid."

[0040] The pretreatment chamber 120 can comprise a housing that encloses the space in which the pretreatment takes place. The pretreatment chamber 120 has a passage on the inlet and outlet sides, which can be closed in other embodiments. This allows the space within the pretreatment chamber 120 to be essentially sealed or decoupled from its surroundings, allowing other conditions (temperature, humidity, pressure) to prevail within the pretreatment chamber 120, at least temporarily.

[0041] The pretreatment chamber 120 has in the embodiment shown Fig. 1 a first section I., a second section II. and a third section III., which in still further embodiments can be separated and sealed off from one another or at least can be separated and sealed off.

[0042] The pretreatment chamber 120 has, in the first section I, at least one first spray device 122 and at least one first heating device 123. The second section II has second spray devices 124. The third section III has at least one second heating device 126 and third spray devices 127.

[0043] The at least one first forming station 130 has an upper first tool part 131 and a lower second tool part 133. The first tool part 131 has a plurality of cavities 132, and the second tool part 133 has a plurality of corresponding mold parts 134. To form products, the two tool parts 131 and 132 are moved relative to one another, with the pretreated areas of the material web 200 being pressed under pressure and temperature input between the surfaces of the cavities 132 and the mold parts 134. For example, the pressing can take place at specific pressures in the range from 100 N / cm² to 5,000 N / cm² and temperatures from 20 (cold pressing) to 250 °C (hot pressing).

[0044] After the forming or pressing in the forming station 130, the pressed products are fed in the transport direction to another station and / or removed from the fiber molding system 100. Optional post-processing of the manufactured products can include, for example, printing, dyeing, filling, stacking, etc. This can be done, for example, in at least one processing station 160, as in Fig. 3 shown schematically.

[0045] In the first section I., during a first pretreatment step, first areas 210 are sprayed via the first spray devices 122 with an additive that changes or influences the properties of the fibrous material in the sprayed area. For example, additives can be applied to the surfaces of the material web 200 from both below and above. As shown in Fig. 2Shown schematically in a plan view, the spraying takes place circularly in the area of ​​the dashed line. The areas 210 provided with the additives are then dried in the first section I. via the first heating devices 123. To achieve this, a cyclical feed takes place, wherein in the embodiment shown, the material web 200 is essentially always only moved by a vertically indicated row of areas 210 in Fig. 2 is moved to the right.

[0046] The material web 200 is then moved further. The previously dried and treated areas 210 are then subjected to further pretreatment in the second section II. via the second spray devices 124. The second spray devices 124 can, for example, wet a section 220 of the material web 200 and thus increase the moisture content. For example, additional additives can be applied. In further embodiments, the entire fibrous material of section 200 of the material web 200 is permeated by steam in the second section II.

[0047] The material web 200 is then transferred to a third section III, in which the material web 200 is first dried via the second heating devices. Subsequently, areas 230 are moistened via the third spray devices 127.

[0048] As in Fig. 2As shown, the regions 210, 230 differ, so that different material properties of the fibrous material of the material web can be achieved through different moistening. In the exemplary embodiment shown, inclined surfaces are subject to greater deformation during pressing in the forming station 130, so that the fibrous material in these regions must have different deformability properties than, for example, in a base region of a bowl, cup, or lid to be produced. This is achieved by the product-specific selective moistening of regions of the fibrous material, which can be subjected to stronger / greater deformation in moist regions than in other regions.

[0049] For example, moistening of areas of the fibrous material can be achieved with a water content of 20 to 50 wt.%. To prevent damage to the material during subsequent pressing at high temperatures, the total moisture content of the material in a mold space between the surfaces of a cavity 132 and a corresponding molded part 134 can be adjusted so that it does not exceed, for example, 20 wt.%. The adjustment is made according to the moistening of the corresponding areas.

[0050] For controlling the production steps and the pretreatment, the fiber molding system 100 also has at least one controller, which in further embodiments is connected to at least one monitoring device (e.g., camera, sensors, etc.) in order to adapt and regulate the moistening of areas of the fiber-containing material and the pretreatment.

[0051] Fig. 3shows a schematic representation of another fiber molding system 100 for producing three-dimensional products from a fibrous material, which additionally has at least a second pretreatment chamber 140 and a second forming station 150. The second pretreatment chamber 140 has a fourth section IV and a V section, in which further additives and / or product-specific moistening of surfaces of the material web 200 to be formed take place.

[0052] For example, in the first pretreatment chamber 120, in addition to the application or introduction of additives, moistening for pre-shaping the fibrous material can take place. Directly after the first pretreatment, the fibrous material is pre-shaped so that it essentially already assumes the shape of the product to be manufactured. Subsequently, further additives (e.g., for a barrier) can be applied in the second pretreatment chamber 140, and the areas to be formed can be (re-)moistened. The final forming or pressing can then take place in the second forming station 150.

[0053] In further embodiments, for example, grooves can be formed in an already formed inclined side wall in a second forming step in a second forming station 150. Other embossed elements can also be incorporated in further embodiments.

[0054] Furthermore, a two-stage molding or pressing process can significantly influence and improve the surface finish and properties of the product being manufactured. For example, after an initial molding step, the entire product can be re-moistened, for example, and then re-pressed at a different pressure and / or temperature.

[0055] A direct (inline), product-specific pretreatment of fibrous material is described, which enables an automatic production process for "dry fiber" in a fiber molding plant 100, wherein there are no restrictions with regard to the product geometry due to the dry fiber material used.

[0056] In a pretreatment chamber 120; 140, one or more states of the fibrous material can be changed in one or more segments (I., II., III. / IV., V.). The fibrous material can be fed from a roll or in blanks and transported through the pretreatment chamber 120; 140. The pretreatment can be carried out on one or both sides, simply or in combined applications, continuously or in process steps. In addition, a selective pretreatment is carried out, whereby product geometry-specific areas are covered with high moisture (20-50%), for example, while the total moisture content can be limited to avoid damage / weakening of the material.

[0057] In addition to increasing elongation and flow behavior, the strength of the formed products is increased, and the surface is smoother and more stable (no linting). Pretreatment is advantageously carried out before a process step, especially a molding step. Pretreatment can also be split up, with a pretreatment step being provided between two process steps, for example, to locally reapply moisture after preforming with a hot mold to create the final product geometry.

[0058] Energy is also saved because less moisture is introduced into the material, meaning less energy is required to remove the moisture during pressing. In other versions, depending on the (total) moisture content, "cold" pressing (e.g., at room temperature, approximately 20 °C) can also be performed, as the moisture can be distributed throughout the product at high pressure, thus preventing localized "wet" areas. List of reference symbols

[0059] 100 Fiber molding system 110 Feed 120 First pretreatment chamber 122 First spray device 123 First heating device 124 Second spray device 126 Second heating device 127 Third spray device 130 First forming station 131 First tool part 132 Cavity 133 Second tool part 134 Mold part 140 Second pretreatment chamber 150 Second forming station 160 Processing station 200 Material web 210 First areas 220 Section 230 Second areas

Claims

1. A method for pretreating fibrous material having a water content of less than 30% by weight in a manufacturing process for producing three-dimensional products, wherein fibrous material is subjected to a product-specific pretreatment before at least one shaping process step of three-dimensional products and the fibrous material is then directly processed further, wherein the fibrous material is at least partially moistened during the product-specific pretreatment.

2. Process according to claim 1, wherein during the product-specific pretreatment at least one temperature, moisture and / or steam treatment and / or an additive treatment of the fibrous material takes place.

3. The method according to claim 1 or 2, wherein the pretreatment comprises at least one pretreatment step.

4. A method according to any one of claims 1 to 3, wherein a selective pretreatment of the fibrous material is carried out.

5. A method according to any one of claims 1 to 4, wherein the fibrous material is supplied to the pretreatment in the form of separate preforms, as a sheet or as a continuous web.

6. The method according to claim 4 and 5, wherein during the selective pretreatment only areas are pretreated which are to be deformed in a subsequent process step.

7. A method according to any one of claims 1 to 6, wherein the pretreatment is carried out at least from one side onto the surface of the fibrous material.

8. The method according to any one of claims 1 to 7, wherein the pretreatment is carried out in several pretreatment steps.

9. Method according to one of claims 1 to 8, wherein the pretreatment takes place within a pretreatment chamber in which the fiber-containing material is at least temporarily protected against external influences.

10. The method according to claim 9, wherein different properties prevail in at least one portion of the pretreatment chamber compared to the environment of the pretreatment chamber, the properties comprising pressure, temperature and / or humidity.

11. Pretreatment chamber for the pretreatment of fibrous material having a water content of less than 30% by weight, wherein the pretreatment chamber is part of a fiber molding plant for producing three-dimensional products, wherein a product-specific pretreatment of the fibrous material can be carried out in the pretreatment chamber, and has at least one pretreatment device with which at least one temperature, humidity and / or steam treatment and / or an additivation of introduced fibrous material can be carried out.

12. Fiber molding plant comprising at least one pretreatment chamber according to claim 11, wherein the at least one pretreatment chamber is arranged upstream of at least one molding station.

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