Method and device for separating absorbent articles

Abstract

The invention relates to a method and a device for recycling a waste stream comprising predominantly absorbent articles wherein said absorbent articles are separated in at least two separate fractions. One fraction predominantly comprises inorganic matter and one fraction predominantly comprises organic matter. Said method comprises the following steps: - Feeding said absorbent articles into a hopper, wherein said hopper comprises at least one conveyor, wherein said absorbent articles are allowed to pass along said conveyor without being shredded; - Transporting the unshredded absorbent articles from said hopper to a separator, wherein said separator comprises a rotating shaft positioned along a longitudinal axis of said separator, wherein said rotating shaft comprises a series of paddles positioned along the length of said rotating shaft, said paddles break open the absorbent articles, thereby generating at least an organic fraction and an inorganic fraction; - physically separating said organic and inorganic fractions based on density, weight and / or size and collecting said fractions into separate collection containers.

Description

[0001] METHOD FOR SEPARATING ABSORBENT ARTICLES

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a method for separating absorbent articles. Specifically, the method makes use of a series of agitators to create a vortex, impact forces and shear stress on said absorbent articles, which constituents are separated based on their respective density and / or size. In a second aspect, the invention relates to a recycled stream based on the separation method of the first aspect.

[0004] BACKGROUND

[0005] Disposable absorbent articles, while convenient and essential for many families, pose significant environmental challenges that have garnered increasing attention in recent years. One of the primary concerns is the sheer volume of waste they generate; it's estimated that billions of these articles are discarded after use each year, contributing to millions of tons of waste which is landfilled or incinerated worldwide. In fact, it is reported that a single child can use thousands of absorbent articles during their infancy and toddler years, resulting in a substantial amount of waste that accumulates in landfills or is incinerated, releasing CO2 into the atmosphere.

[0006] The composition of disposable absorbent articles is another major issue. They are typically made from a combination of non-biodegradable materials, such as polyethylene and polypropylene, as well as superabsorbent polymers designed to lock in moisture. These materials can take hundreds of years to break down, leading to a slow and ongoing decomposition process that exacerbates landfill overcrowding. Moreover, the presence of synthetic materials in absorbent articles poses challenges for composting efforts, as these materials are not easily separable from organic components, while the organic components pose issues for recycling.

[0007] The slow decomposition and overwhelming volume of discarded absorbent articles create a lasting ecological burden, highlighting the urgent need for effective recycling solutions. By developing methods to separate and recover the organic and inorganic components of disposable absorbent articles, innovations in this field can significantly mitigate their environmental impact, promoting a more sustainable approach to waste management.

[0008] SUMMARY OF THE INVENTIONThe present invention and embodiments thereof serve to provide a solution to one or more of above-mentioned disadvantages. To this end, the present invention relates to a method for separating absorbent articles according to claim 1. Further embodiments are described in claims 2 to 17.

[0009] The invention significantly enhances the recycling process for absorbent articles, particularly disposable diapers, by efficiently separating them into distinct organic and inorganic fractions without shredding. This method preserves the integrity of materials, improving their separability and recyclability. Utilizing a twin-screw conveyor, the system tears open any bags in which the articles are received and gently transports the whole articles so as to minimize damage, while a rotating shaft with strategically positioned paddles breaks open the absorbent materials to maximize recoverable yield.

[0010] The separation leverages the differing densities of organic and inorganic components, allowing for physical segregation and reducing cross-contamination through dedicated outlets.

[0011] The design incorporates paddles that create shear and impact forces, enhancing separation efficiency. The system prevents clogging and supports smooth operations through an inclined hopper design, which can feature shaftless twin-screw conveyors for flexibility and reduced maintenance.

[0012] Additionally, agitation structures within the separator's walls promote turbulence, optimizing the movement of materials and preserving the integrity of the inorganic fraction, typically non-woven polymer sheets. The organic fraction includes cellulose, organic waste, and super absorbent materials (SAPs).

[0013] In a second aspect, the invention relates to a recycled stream according to claims 18 to 20.

[0014] In a third aspect, the invention relates to a use of a recycled stream according to claim 21.

[0015] In a fourth aspect, the invention relates to a device according to claims 22 to 23.DESCRIPTION OF FIGURES

[0016] The following description of the figures of specific embodiments of the invention is merely exemplary in nature and is not intended to limit the present teachings, their application or uses. Throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

[0017] Figure 1 shows a schematic side view of an embodiment of the present invention.

[0018] Figure 2 shows a schematic cross section of an embodiment of the present invention.

[0019] Figure 3 shows a schematic side view of a detail of an embodiment of the present invention.

[0020] DETAILED DESCRIPTION OF THE INVENTION

[0021] Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention.

[0022] As used herein, the following terms have the following meanings:

[0023] "A", "an", and "the" as used herein refers to both singular and plural referents unless the context clearly dictates otherwise. By way of example, "a compartment" refers to one or more than one compartment.

[0024] "About" as used herein referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, is meant to encompass variations of + / -20% or less, preferably + / -10% or less, more preferably + / -5% or less, even more preferably + / -1% or less, and still more preferably + / -0.1% or less of and from the specified value, in so far such variations are appropriate to perform in the disclosed invention. However, it is to be understood that the value to which the modifier "about" refers is itself also specifically disclosed.

[0025] "Comprise", "comprising", and "comprises" and "comprised of" as used herein are synonymous with "include", "including", "includes" or "contain", "containing","contains" and are inclusive or open-ended terms that specifies the presence of what follows e.g. component and do not exclude or preclude the presence of additional, non-recited components, features, element, members, steps, known in the art or disclosed therein.

[0026] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order, unless specified. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0027] The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within that range, as well as the recited endpoints.

[0028] The expression "% by weight", "weight percent", "%wt" or "wt%", here and throughout the description unless otherwise defined, refers to the relative weight of the respective component based on the overall weight of the formulation.

[0029] Whereas the terms "one or more" or "at least one", such as one or more or at least one member(s) of a group of members, is clear per se, by means of further exemplification, the term encompasses inter alia a reference to any one of said members, or to any two or more of said members, such as, e.g., any >3, >4, >5, >6 or >7 etc. of said members, and up to all said members.

[0030] Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, definitions for the terms used in the description are included to better appreciate the teaching of the present invention. The terms or definitions used herein are provided solely to aid in the understanding of the invention.

[0031] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures orcharacteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0032] In a first aspect, the invention relates to a method for recycling a waste stream comprising predominantly absorbent articles wherein said absorbent articles are separated in at least two separate fractions. One fraction predominantly comprises inorganic matter, comprising synthetic polymers such as polypropylene and polyethylene; and one fraction predominantly comprises predominantly organic matter, comprising super absorbent polymers, cellulose fiber and human excrements. Said method comprises the following steps:

[0033] • Feeding said absorbent articles into a vessel, such as a hopper, wherein said hopper allows the absorbent articles to pass along said conveyor without being shredded;

[0034] • Transporting the unshredded absorbent articles from said hopper to a separator, wherein said separator comprises a rotating shaft positioned along a longitudinal axis of said separator, wherein said rotating shaft comprises a series of paddles positioned along the length of said rotating shaft, said paddles break open the absorbent articles, thereby generating at least an organic fraction and an inorganic fraction;

[0035] • physically separating said organic and inorganic fractions based on density, weight and / or size.

[0036] In an embodiment, the hopper can comprise or be connected to a conveyor. This conveyor can be belt, screw, chain, roller, bucket or vibratory conveyors. In a preferred embodiment, the conveyor is a screw conveyor. Furthermore, the conveyor can be a twin-screw conveyor.

[0037] In this context, "unshredded" refers to a material that remains in its original or whole form and has not been cut, torn, or broken down into smaller pieces or fragments, wherein said pieces or fragments have a size that are smaller than half of the original size of the material. Unshredded does in this context not mean that the originalmaterial remains entirely intact, but rather that it is not deliberately cut, torn, or broken down into smaller pieces or fragments.

[0038] Disposable absorbent hygiene products, such as diapers, are designed to absorb and retain bodily fluids, providing comfort and dryness to the user. Diapers are primarily used for babies, young children, and individuals with incontinence issues. They are constructed with multiple layers, each serving a specific purpose to enhance the product's absorbency, comfort, and durability.

[0039] The top layer, or top sheet, is made from a soft, non-woven fabric that allows liquid to pass through while keeping the skin dry. This layer is typically made of materials like polypropylene or polyethylene, which are chosen for their softness and ability to wick moisture away from the skin, helping to prevent irritation. Beneath the top sheet is the absorbent core, which is the heart of the diaper. The core is a combination of fluff pulp (e.g. cellulose fibers) and superabsorbent polymers (SAP). The fluff pulp helps to distribute the liquid, while the SAP, a material capable of absorbing many times its weight in liquid, transforms into a gel-like substance, preventing leaks and keeping the moisture locked away from the skin. Between the top sheet and the absorbent core there may be additional layers of non-woven fabric to aid in the acquisition and distribution of moisture to the absorbent core. These layers are typically made of materials such as polypropylene or polyester.

[0040] The back sheet, or outer layer, generally comprises a layer, typically made of a waterproof material, such as polyethylene film, which is bonded to a soft, non-woven fabric layer, typically made from polypropylene. The waterproof layer prevents liquids from leaking through the diaper. This layer may also be breathable, allowing air to circulate and reduce the risk of diaper rash. The non-woven layer provide a soft touch and protection of the waterproof layer. Additional features like elastic leg cuffs and fasteners ensure a snug, comfortable fit, while preventing leaks around the legs and waist. Diapers may also include odor control elements and lotions or additives on the top sheet to provide additional skincare benefits.

[0041] The various materials in absorbent articles make them particularly challenging to recycle. Each article contains a mix of organic (such as cellulose) and inorganic components (like synthetic polymers), which need to be separated for any effective recycling process. Effective separation of these constituents could significantly reduce the environmental impact of disposable absorbent articles, transforming them from a single-use disposable product into a source of recyclable materials.In an embodiment, the separator is cylindrically shaped, wherein the input stream is let in on one proximal end and an output stream is let out on the opposite, distal end of the separator. Herein, said inlet is connected to the end of the hopper. Furthermore, a second output stream can be let out of a second outlet, positioned on the lateral side of the separator, specifically on the bottom side.

[0042] In an embodiment, the absorbent articles are separated based on physical characteristics of their constituent materials. As described above, said articles are comprised of two fractions, being an organic fraction (SAPs, cellulose and human excrements) and an inorganic fraction (plastics, such as polypropylene or polyethylene). In an embodiment, the inorganic fraction has a lower density compared to the organic fraction. As a consequence, the organic fraction is heavier and will be less able to move forward in the separator, and subsequently will fall to the bottom of the separator. Said organic matter can then be discharged at the bottom of the separator.

[0043] In an embodiment, the underside of the separator comprises a screen with a mesh size between 10 mm and 100 mm, preferably between 10 mm and 80 mm, preferably between 30 mm and 70 mm, most preferably around 30 mm. The screen positioned at the bottom of the separator serves to filter and discharge the organic matter. Its primary function is to allow only the smaller organic particles, such as cellulose fibers and other biodegradable materials, to pass through while retaining larger, non-degradable components within the separator. This selective passage ensures that the organic fraction is separated effectively, enabling it to exit through the bottom outlet. Additionally, the screen can control the size of the particles in the organic output stream, as the mesh size of the screen determines which particles can pass through. This helps improve the purity of the separated fractions, facilitating more efficient downstream processing and recycling of the organic matter. In a preferred embodiment, the organic matter is discharged through the screen positioned at the bottom of the separator, wherein said screen has a mesh size of around 30 mm.

[0044] The inorganic fraction, having a lower density than the organic fraction, is designed to follow a vortex path within the separator. This vortex path is created by the rotational motion of the shaft, which, combined with the specific shape and positioning of the paddles, generates a swirling movement of the materials inside the separator. This swirling or vortex effect helps to propel the lighter, inorganicparticles, such as non-woven polymer sheets and plastic materials, toward the far end of the separator.

[0045] In one embodiment, the separator includes an outlet specifically positioned at the distal end, opposite the inlet, where the inorganic fraction is discharged. As the materials progress along the vortex path, the lighter, inorganic components naturally separate from the heavier organic matter, which is discharged through a screen at the bottom. This distal outlet at the end of the vortex path is strategically placed to ensure that only the inorganic fraction, which has followed the spiral movement, exits the separator through this route. By configuring the outlet in this manner, the invention enhances the efficiency of the separation process, facilitating a continuous flow that isolates the different materials for easier collection and subsequent recycling.

[0046] The separator is equipped with at least two outlets for discharging the separated organic and inorganic fractions, each designed to streamline the collection and transport of these materials. The first outlet, positioned at the bottom of the separator, is dedicated to the organic fraction. This outlet allows organic materials, such as cellulose and other biodegradable substances, to exit the separator. Connected to this bottom outlet is a hopper equipped with a conveyor, which might be a screw conveyor or a twin-screw conveyor. The conveyor efficiently transports the organic matter from the separator to a suitable container, where it can be collected and prepared for further processing or recycling. The conveyor can be a screw conveyor with a rotational speed between 50 and 60 rpm. In another embodiment, the bottom outlet comprises another transportation system than a conveyor.

[0047] Similarly, the inorganic fraction is discharged through a second outlet, located at the distal end of the separator, opposite the inlet. This side outlet is specifically positioned to accommodate the lighter, lower-density inorganic materials, such as non-woven polymer sheets and plastics, which follow a vortex path along the separator's interior. The side outlet is also connected to a hopper, which has its own conveyor that directs the inorganic waste toward a separate collection container. This conveyor can be a screw conveyor with a rotational speed between 80 and 90 rpm. This setup allows the inorganic materials to be efficiently removed from the separator and collected for potential recycling or disposal. By incorporating individual outlets and conveyors for each fraction, this system facilitates a smooth andorganized separation process, reducing cross-contamination and enhancing the purity of the recycled materials.

[0048] The inorganic fraction, which typically consists of non-biodegradable materials like non-woven polymer sheets, plastic films, and other synthetic components, has several potential applications once separated and collected. After being discharged from the separator through the side outlet and conveyed to a collection container, this fraction can be further processed to maximize its recycling potential.

[0049] One practical approach for handling the inorganic fraction is to implement an automatic baling system. Once the material has accumulated in the container, an automated baler can compress the plastic and other synthetic materials into dense, manageable bales. This process significantly reduces the volume of the inorganic waste, making it easier and more cost-effective to transport and store. Baling also prepares the inorganic fraction for downstream recycling facilities, where it can be sorted, cleaned, and potentially reprocessed into new products. For instance, nonwoven sheets and plastic films from diapers may be repurposed into plastic pellets, which can then be used as raw materials in the manufacturing of items such as park benches, plastic lumber, or even new non-woven fabrics for various industrial applications. Another option is advanced or chemical recycling (e.g. by pyrolysis) which removes all possible contamination, converts the plastic into a kind of oil, naphtha and / or gas and enables new polymers to be produced using this hydrocarbon as a basis. These new chemically recycled materials are as pure, if not purer than virgin polymers made from crude oil.

[0050] In addition to baling, this fraction can be sorted further to separate specific polymers or other valuable materials. Automated sorting technologies, such as optical sorters, can detect and segregate materials based on their composition, enhancing the purity and value of the recycled outputs. By implementing automated baling and advanced sorting processes, the inorganic fraction from absorbent hygiene products can become a valuable resource stream, reducing the environmental footprint associated with disposable diapers and promoting a more circular economy.

[0051] In an embodiment, a further option is densification of this fraction into a pellet, granule or agglomerate. This may include steps of shredding, washing and or drying prior to densification. This takes the bulk density of this fraction from about 30-60kg / m3up to about 300-400kg / m3and would enable efficient storage, transport and feeding into a mechanical or chemical recycling or production process.In an embodiment, in the separator, a rotating shaft is present along the full length of the separator. The length here is specified as the longest dimension of the separator. The rotating shaft has a rotational speed between 100 rpm and 1100 rpm, preferably between 200 rpm and 1000 rpm, preferably between 300 rpm and 900 rpm, preferably between 300 rpm and 720 rpm, preferably between 400 rpm and 800 rpm, preferably between 600 rpm and 720 rpm. This range allows for sufficient agitation and movement of the absorbent articles without overly damaging the materials or creating excessive wear on the equipment. By maintaining the shaft's rotational speed within the specified range, the system can achieve a balance between effective separation and the integrity of the materials, ensuring that both organic and inorganic fractions are produced efficiently. In an embodiment, the shaft comprises a series of paddles. These paddles can be various in shape and dimension. In a further embodiment, all paddles have the same shape and dimension. The paddles are positioned tangentially on the rotational shaft, which can harbor 1, preferably 2, more preferably 3, most preferably 4 rows of paddles. In an embodiment, at least 1, preferably at least 2, preferably at least 3, preferably at least 4, preferably at least 5, preferably at least 6, preferably at least 7, preferably at least 8, preferably at least 9, preferably at least 10, preferably at least 11, preferably at least 12, preferably at least 13, preferably at least 14, preferably at least 15, preferably at least 16, preferably at least 17, preferably at least 18 are present on each row. Each row can comprise an equal or a different amount of paddles.

[0052] In an embodiment, the paddles can be double ended paddles, wherein a paddle is rectangularly shaped with dimensions, rounded corners and a curved top edge. The dimensions comprise a width between 100 mm and 150 mm, preferably between 110 mm and 130mm, wherein the width is defined as the dimension of the side parallel to the rotating shaft. The dimensions further comprise a length between 100 mm and 200 mm, preferably between 120 mm and 180 mm, more preferably between 140 mm and 160 mm, wherein the length is defined as the dimension of the side perpendicular to the rotating shaft

[0053] The function of paddles is to agitate the stream, creating impact force in order to separate the organic from the inorganic matter. Furthermore, the paddles create a vortex path due to the rotational speed of the rotating shaft. Said paddle comprises an impact plate, a round shaft and a clamp block comprising at least one bolt toclamp the plate to the shaft. In an embodiment, the clamp block comprises at least two bolts to prevent rotation of the paddle.

[0054] In an embodiment, the tip gap, which is the distance between the end of the impact plate and the central edge of the ribs of the separator, is adjustable within the interval of 5 mm and 100 mm, preferably between 5 mm and 80 mm, preferably between 5 mm and 60 mm, preferably between 5 mm and 50 mm, most preferred between 5 mm and 30 mm. In some embodiments, different paddles have different tip gaps. For example, the 6 paddles closest to the inlet can be set with a tip gap of between 30 mm and 50 mm, whereas the paddles further away can be set with a tip gap of between 10 mm and 30 mm.

[0055] In an embodiment, the paddle angle can be adjusted between 0 degrees and 90 degrees, toward the inlet or toward the opposite side, relative to the length of the rotational shaft. All paddles can be set in the same angle, or paddles can be set in different angles. In an embodiment, paddles are set in 15-degree increments, where the paddles at the inlet are set at 90 degrees and each subsequent paddle is set 15 degrees less than the previous. This will result in an optimal air flow of the machine. In another embodiment, all paddles will be tilted slightly, between 0 and 30 degrees, with 1 or 2 paddles per row at 90 degrees. This configuration will allow a forward pushing of the material, while the perpendicular paddles provide a cutting action and allow material to pass between chambers of paddles.

[0056] In an embodiment, and when the absorbent articles enter the separator, they encounter paddles oriented to push materials forward. Paddles facing backward exert a counteracting force on the articles. This design compels the absorbent materials to momentarily move backward, effectively increasing their retention time within the separator. The extended retention time is favored for several reasons. Firstly, it allows the absorbent articles to be subjected to more mechanical forces, promoting their breakdown and facilitating the separation of organic and inorganic components. As the materials experience this agitation, they become more accessible for effective processing.

[0057] Secondly, the opposing paddles help create turbulence within the separator, enhancing mixing and promoting a more thorough interaction between the absorbent articles and the paddles. This interaction allows for improved separation and sorting of materials based on density and size, enabling a clearer distinction between organic and inorganic fractions as they are transported through the separator. Furthermore,the configuration of paddles facing opposite directions can help prevent material clogging. By maintaining a continuous motion of the absorbent articles and keeping them in flux, the risk of stagnation is minimized, ensuring a consistent flow through the separator.

[0058] In an embodiment, the inlet of the separator is connected to a hopper. This hopper can comprise at least one conveyor, preferably at least one screw conveyor, more preferably at least one twin-screw conveyor, wherein both screw conveyors rotate in the same direction. These screw conveyors can comprise a shaft, preferably the screw conveyors do not comprise a shaft.

[0059] One significant advantage of shaftless conveyors is their enhanced flexibility in design and layout. By eliminating the central shaft, the conveyor can accommodate varying widths and shapes, allowing for a more compact and efficient use of space within the overall system. This flexibility can be particularly beneficial in systems where space constraints exist or where the design needs to be customized to fit specific operational requirements.

[0060] Another technical effect of a shaftless design is the reduction in maintenance requirements. Traditional screw conveyors with shafts may suffer from issues related to shaft wear, misalignment, and the need for regular lubrication. In contrast, shaftless conveyors typically have fewer moving parts, reducing the likelihood of mechanical failure and the associated downtime for repairs and maintenance. This can lead to lower operational costs and increased reliability in the recycling process.

[0061] Additionally, shaftless screw conveyors can provide improved material handling capabilities. Without a shaft, there is less risk of material buildup or blockages, ensuring a smoother and more continuous flow of absorbent articles into the separator. This design can also facilitate better mixing and transportation of materials, as the absence of a shaft allows for a more uniform distribution of ferees acting on the material as it moves through the conveyor.

[0062] In an embodiment, the hopper is positioned at an incline, enabling the screw conveyor to guide the absorbent articles from a lower container upwards to the inlet of the separator. This inclined design offers several advantages. First, the upward orientation of the screw conveyor utilizes mechanical energy efficiently to transport the absorbent articles from a lower elevation to the higher inlet of the separator. This configuration allows for effective lifting of the materials, ensuring that they aredelivered consistently and reliably to the separator without the need for additional lifting mechanisms.

[0063] Second, the inclined hopper promotes a continuous flow of absorbent articles into the separator. By facilitating the upward movement, the design helps prevent material buildup or clogging in the conveyor system, ensuring smooth operation. The screw conveyor's helical action effectively moves the articles upward while minimizing the risk of damage to the materials, maintaining their integrity during transport.

[0064] Finally, the inclined design can improve accessibility for maintenance and monitoring. With the absorbent articles moving from a lower container to the higher inlet, operators can more easily observe the flow and condition of the materials within the system.

[0065] In an embodiment, the twin-screw conveyors move at the same speed. In a preferred embodiment, the twin-screw conveyors move at a different speed, between 1 rpm and 10 rpm, preferably between 3 rpm and 5 rpm. The difference in rotational speed, creates shear stress that aids in opening the bags wherein absorbent articles are delivered to the hopper. Furthermore, by rotating one conveyor at a slower pace than the other, the input stream can be paced according to the optimal input of the separator. In an embodiment, the separator requires a steady input, without overflowing the machine.

[0066] In an embodiment, the absorbent articles are hygienic products, preferably diapers and / or wet wipes. In a preferred embodiment, the diapers are specifically designed for babies and / or children. Baby and / or children's diapers are defined in this context as diapers intended for use by children or babies, wherein the user of said diaper weighs less than 30 kg. This weight limit typically encompasses children from birth up to approximately seven years of age, covering various stages of development and toilet training.

[0067] In an embodiment, the design of these baby diapers is tailored to accommodate the specific needs of younger users, focusing on factors such as comfort, absorbency, and fit. For instance, they often feature soft, breathable materials that provide gentle contact with the sensitive skin of infants and toddlers, reducing the risk of irritation or diaper rash. Additionally, the absorbent core of these diapers is engineered toquickly wick moisture away from the skin while locking it in, thereby keeping the child dry and comfortable for extended periods.

[0068] In the context of recycling, focusing on baby and children's diapers is significant due to their prevalence in waste streams. By targeting this specific category of absorbent articles for recycling, the invention aims to address the environmental burden associated with disposable diapers, which contribute substantially to landfill waste or incineration. The efficient separation and recovery of materials from these diapers can lead to more sustainable waste management practices and reduce the ecological impact of disposable hygiene products. Furthermore, baby or children diapers comprise little to no medicinal contamination, as opposed to adult diapers. In an embodiment, prior to the separation, used or unused absorbent articles, such as diapers, are collected in a container. Said container can be a case, trunk or bag, such as a plastic bag or a waste bag, storage box, lined or unlined carboard box, waste container with or without wheels.

[0069] In an embodiment, the diapers comprise super absorbent polymers, which are integral to their design, offering superior moisture retention and absorption capacity. SAPs can absorb many times their weight in liquid, allowing diapers to remain effective for extended periods, providing comfort and dryness for the user. The inclusion of SAPs ensures that the diapers are both highly functional and capable of meeting the needs of users without frequent changes, which can be particularly beneficial during long outings or overnight use.

[0070] In an embodiment, the input stream of the separator comprises a mixed stream, comprising at least 50% diapers, preferably at least 70% diapers, preferably at least 80% diapers, preferably at least 90% diapers, preferably at least 99% diapers. In a further embodiment, the input stream comprises no mixed stream and the input comprises 100% diapers, preferably baby or child diapers. The presence of a high diaper content in the mixed stream ensures that the separator operates with a material that is relatively uniform in composition, allowing for optimized process parameters tailored to diaper recycling. This will lead to an increased separation efficiency, higher material recovery and an energy and cost efficient process.

[0071] In an embodiment, the walls of the separator comprise structures to increase agitation. The walls of the inlet and outlet can also comprise similar or equal agitators. These structures can comprise ribs, protrusions, baffles, grooves or a combination thereof, strategically positioned along the interior walls to promote theeffective movement and tumbling of the absorbent articles as they pass through the separator. The added turbulence created by these structures can improve the separation of organic and inorganic component, as it helps dislodged materials from one another and exposes them to further processing by the paddles on the rotating shaft. Besides the turbulence, the agitators cause the diapers to get squashed, squeezed and / or sheared between the agitators and the paddles as the shaft rotates. This leads to tearing of the sheets and allows organic material to be removed.

[0072] In a preferred embodiment, the lateral side of the separator comprises ribs with dimensions. The dimensions comprise a length which is equal to the length of the separator. The dimensions further comprise a width between 5 and 50 mm, preferably between 10 and 40 mm, more preferably between 20 and 35 mm, wherein the width of the rib is the length of the surface parallel to the side of the separator. The dimensions further comprise a height between 5 mm and 30 mm, more preferably between 10 mm and 20 mm, wherein the height is the length of the side perpendicular to the separator. These dimensions are chosen for an optimal agitation without damaging or shredding the inorganic material, ensuring that the material is adequately disturbed without causing damage or shredding to the inorganic components.

[0073] Said agitation structures work in tandem with the paddles on the rotating shaft to improve the separation efficiency. As the rotating shaft propels the absorbent articles forward, the ribs create additional contact points, causing the materials to tear, shift and tumble. This motion exposes more surface area of the diapers or other absorbent articles to the separation forces, helping to loosen the bonds between organic components and the inorganic back sheets.

[0074] Moreover, the design of the agitation structures can vary depending on the specific needs of the recycling process. For example, the structures can be spiral ribs that can create a controlled flow pattern. In an embodiment, the structures can be sawtooth grooves, typically angled to generate turbulence within the separator, helping to break open the absorbent articles. In a further embodiment, these structures can be protruding baffles.

[0075] In an embodiment, the inorganic matter comprises one or more non-woven sheets, preferably polymer sheets. These sheets are typically derived from the back sheet or other structural layers of the absorbent articles, such as diapers, and often contain synthetic polymers like polypropylene or polyethylene. In a further embodiment, theinorganic matter may comprise polyethylene terephthalate (PET), polylactic acid (PLA), polyurethane, polyacrylate, polyvinyl alcohol, polyvinyl acetate, polyester, and elastomers like styrene-butadiene-styrene (SBS) or polyether block amide (PEBA). The inorganic matter furthermore comprises all components that are glued together. In a preferred embodiment, the output stream of inorganic matter is still intact or comprises limited damage, meaning that the sheets maintain their structural integrity to a significant extent. This intactness reduces the presence of inorganic components in the organic fraction. This output stream can comprise 70% to 100%, preferably around 85% polypropylene, the remainder of the output comprises polyethylene.

[0076] In this context, "damage" refers to physical degradation of the sheets, including tearing, shredding or significant deformation into smaller pieces. Damage can be assessed with a visual inspection, where samples are graded based on the extent of visible degradation. Furthermore, tensile strength can be quantified, measuring the material's resistance to tearing. In an embodiment, the sheets retain at least 50%, preferably at least 60%, preferably at least 70%, preferably at least 80%, preferably at least 90% of their original tensile strength. In an embodiment, damage is measured via surface area measurements. At least 50%, preferably at least 60%, preferably at least 70%, preferably at least 80%, preferably at least 90% of the original surface area remains intact.

[0077] The end-use potential of the inorganic fraction is considered. Intact sheets with minor or no damage are ideal for processes such as baling or automatic baling, which allows for compact, stable bales that are easily transported.

[0078] In an embodiment, the organic matter obtained from used absorbent articles comprising a high proportion of human excreta comprises between 2% and 20% cellulose, between 2% and 20% SAP and between 65% and 96% excreta.

[0079] Said organic waste comprises human excrements, excluding any form of medical waste, to ensure a more consistent and manageable composition for further processing. In a later stage, the organic matter might be processed further to separate various fractions, allowing for the recovery and repurposing of specific components. For instance, cellulose fibers can potentially be isolated and repurposed for applications requiring biodegradable materials, while SAPs may be recovered and reused for absorbent products. This secondary separation enhances the overall recycling process, transforming waste into valuable resources and contributing to amore sustainable approach to managing used absorbent products. The cellulose fiber can be purified and reused in, for example, manufacturing of paper, cardboard, textiles, construction materials and / or coatings. The polypropylene and polyethylene blends can be reprocessed into new plastic products. Furthermore, the SAP may be used as a modifier in cement manufacturing or pressure sensitive adhesives, and for coating underwater cables.

[0080] In an embodiment, the underside of the separator comprises a mesh screen, wherein the mesh comprises circular holes with a diameter between 20 mm and 60 mm. The mesh can comprise other forms of holes as well, such as rectangular, square or oval. Preferably the holes have a round shape in order to avoid material getting caught in sharp corners. In an embodiment all holes have the same shape and size. The holes can have a honeycomb pattern or can be placed in regular lines. The shape and dimensions of the mesh play a role in the behavior or the organic matter. The holes must be large enough for the organic matter, which comprises various sizes, to be adequately discharged. Furthermore, larger holes facilitate more tearing and said polymeric material comprises polypropylene separation, but also possibly more contamination of inorganic material in the organic fraction. Smaller holes avoid this, but cause less tearing.

[0081] A second aspect of the invention relates to a recycled stream derived from used and / or unused absorbent articles, preferably diapers, wherein said stream is obtained by means of a separation process of said absorbent article for the purpose of recycling. The stream comprises two physically separated fractions, wherein a first fraction comprises organic material selected from cellulose, organic waste, super absorbent material or a mixture thereof; and wherein a second fraction comprises inorganic matter, said inorganic matter comprises a plurality of non-woven sheets, wherein each non-woven sheet is derived from the sheet material of a separated absorbent article and wherein the surface area of the non-woven sheet is at least 50% of the surface area of the sheet material of the absorbent article prior to separation.

[0082] In an embodiment of the recycled stream, the inorganic fraction obtained by the method described herein comprises predominantly polymeric material. Based on dry weight and depending on the composition of the input absorbent articles, said inorganic fraction may comprise at least 70 wt%, preferably at least 80 wt%, more preferably at least 85 wt% polymeric material.In a further embodiment, said polymeric material comprises polypropylene (PP) and polyethylene (PE), optionally further comprising one or more additional polymeric materials, such as polyester, for example polyethylene terephthalate (PET). By way of non-limiting example, the inorganic fraction may comprise polypropylene in an amount between 40 wt% and 80 wt%, polyethylene in an amount between 10 wt% and 40 wt%, and polyethylene terephthalate in an amount up to 10 wt%, based on the dry weight of the inorganic fraction. In a further embodiment, the inorganic fraction may further comprise trace amounts of one or more additional polymers, such as polyamides, polystyrenes, polyurethanes, elastomers or combinations thereof, typically originating from auxiliary components of the absorbent articles, wherein said additional polymers are present in an amount of less than 5 wt%, preferably less than 3 wt%, based on the dry weight of the inorganic fraction.

[0083] The inorganic fraction may further comprise residual non-polymeric material, such as fillers, ash, adhesives or adhesive residues, typically in an amount of less than 20 wt%, preferably less than 15 wt%.

[0084] In an embodiment of the recycled stream, the organic fraction obtained by the method described herein comprises cellulose fibers, superabsorbent polymers (SAP) and organic waste, including human excreta. Based on dry weight and depending on the design and composition of the input absorbent articles, said organic fraction may comprise between 10 wt% and 60 wt% cellulose fibers and between 40 wt% and 90 wt% superabsorbent polymers.

[0085] In a further embodiment, the organic fraction comprises cellulose fibers in an amount between 20 wt% and 50 wt% and superabsorbent polymers in an amount between 50 wt% and 80 wt%, wherein the remainder comprises organic waste.

[0086] The skilled person will appreciate that the relative amounts of polymeric material, cellulose fibers, superabsorbent polymers and organic waste depend strongly on the architecture and material balance of the absorbent articles forming the input stream and may vary substantially, for example in absorbent articles comprising reduced or substantially no cellulose content.

[0087] The compositional ranges described herein are provided by way of illustration and are not intended to limit the scope of the invention. Unless explicitly stated otherwise, all percentages refer to dry weight and exclude moisture content.In the context of this invention, "sheet material" refers to a flexible, planar layer or web-like structure that includes, but is not limited to, nonwoven fabrics, polymer films or laminated composited, which are designed to provide functionalities such as liquid permeability or impermeability, or structural support within the absorbent article. Sheet material may include, but is not limited to, back-sheet, top-sheet, acquisition and distribution layer, elastic side panels, leg cuffs and / or leakage barriers.

[0088] In an embodiment, the stream is obtained by the method described as above. In a preferred embodiment, the absorbent articles are diapers.

[0089] A third aspect of the invention relates to a use of a recycled stream comprising two physically separated fractions. Herein, a first fraction comprises organic material selected from cellulose, organic wase, super absorbent material or a mixture thereof and a second fraction comprises inorganic matter. The inorganic matter comprises a plurality of non-woven sheets, wherein each non-woven sheet is derived from the sheet material of a separated absorbent article and wherein the surface area of the non-woven sheet is at least 50% of the surface area of the sheet material of the absorbent article prior to separation. In the context of this invention, the non-woven sheet material has the same definition as described above.

[0090] In a fourth aspect of the invention, the invention relates a device for separating and / or recycling absorbent articles, preferably according to the method described above. In an embodiment, this device comprises a hopper, wherein said hopper comprises at least one twin-screw conveyor. Furthermore, the device comprises a separator, wherein said separator comprises a rotating shaft positioned along a longitudinal axis of the separator. The rotating shaft comprises a series of paddles positioned along the length of said rotating shaft, which break open the absorbent articles, thereby generating at least an organic fraction and an inorganic fraction. According to an embodiment, the device comprises two outlets, one for each fraction of the absorbent articles.

[0091] The organic fraction which is generated as output can comprise super absorbent polymers (SAPs), cellulose fibers and human excreta. The inorganic fraction comprises plastic, like polypropylene or polyethylene. According to an embodiment, the absorbent articles are introduced in said device unshredded, meaning that the absorbent articles are not mechanically fragmented or broken down prior to enteringthe device. Also during the process, the absorbent articles remain unshredded, albeit they undergo limited structural damage without full disintegration or fragmentation.

[0092] In an embodiment, in the separator, a rotating shaft is present along the full length of the separator. In an embodiment, the shaft comprises a series of paddles. These paddles can be various in shape and dimension, as described above. In total, the shaft could comprise 1 to 80 paddles. In an embodiment, the underside of the separator comprises a screen with a mesh as described above. The screen positioned at the bottom of the separator serves to filter and discharge the organic matter.

[0093] In an embodiment, the device is used for separating and / or recycling diapers, preferably baby diapers.

[0094] The present invention will be now described in more details, referring to examples that are not limitative.

[0095] EXAMPLES AND / OR DESCRIPTION OF FIGURES

[0096] Figure 1 shows a side view of a device (1) according to an embodiment of the invention. The separator (2) is cylindrical in shape and comprises two distal sides and a top and bottom. The separator comprises one inlet (3) and two outlets (4, 5). The inlet is positioned at one distal side at the top side of the separator. The inlet is connected to a hopper (6) with one twin-screw conveyor (7, not depicted), wherein absorbent articles are allowed to pass along the conveyor (7). Both conveyors of the twin-screw rotate in the same direction at different speeds. The conveyor (7) is positioned at an incline of 30°, enabling the screw conveyor to guide the absorbent articles from a lower container upwards to the inlet of the separator.

[0097] The separator is equipped with two outlets (4, 5) for discharging the separated organic and inorganic fractions, each designed to streamline the collection and transport of these materials. The first outlet (4), positioned at the bottom of the separator, is dedicated to the organic fraction. This outlet allows organic materials, such as cellulose and other biodegradable substances, to exit the separator. Connected to this bottom outlet is a hopper (8, not depicted) equipped with a singlescrew conveyor. The conveyor efficiently transports the organic matter from the separator to a suitable container, where it can be collected and prepared for further processing or recycling.Similarly, the inorganic fraction is discharged through a second outlet (5), located on the side of the separator. This side outlet is specifically positioned to accommodate the lighter, lower-density inorganic materials, such as non-woven polymer sheets and plastics, which follow a vortex path along the separator's interior. The side outlet is also connected to a single-screw conveyor that directs the inorganic waste toward a separate outlet that can be connected to a collection container. This setup allows the inorganic materials to be efficiently removed from the separator and collected for potential recycling or disposal. By incorporating individual outlets and conveyors for each fraction, this system facilitates a smooth and organized separation process, reducing cross-contamination and enhancing the purity of the recycled materials.

[0098] Figure 2 shows a cross-section of a device (1) according to an embodiment of the invention. The separator (2) is cylindrical in shape and comprises two distal sides and a top and bottom. The separator comprises one inlet (3) and two outlets (4, 5). The inlet (3) is positioned at one distal side at the top side of the separator. The inlet is connected to a hopper (6) with one twin-screw conveyor (7), positioned at an incline of 30°, enabling the screw conveyor to guide the absorbent articles from a lower container upwards to the inlet of the separator. The first outlet (4), positioned at the bottom of the separator, is dedicated to the organic fraction. Said outlet is conical in shape and converges towards its outlet. The inorganic fraction is discharged through a second outlet (5), located on the side of the separator. This second outlet is coupled to a screw conveyor on an incline, at an angle of 30°.

[0099] A rotating shaft is present along the full length of the cylindrical separator. The length here is specified as the longest dimension of the separator. The rotating shaft has a rotational speed between 600 rpm and 720 rpm. This range allows for sufficient agitation and movement of the absorbent articles without overly damaging the materials or creating excessive wear on the equipment. By maintaining the shaft's rotational speed within the specified range, the system can achieve a balance between effective separation and the integrity of the materials, ensuring that both organic and inorganic fractions are produced efficiently.

[0100] The shaft comprises a series of paddles. All paddles have the same shape and dimension. The paddles are positioned in 4 rows on the rotational shaft, with each 18 paddles.The walls of the separator comprise structures to increase agitation. These structures are ribs with a width between 5 and 50 mm, preferably between 10 and 40 mm, more preferably between 20 and 35 mm; and a height between 5 mm and 30 mm, more preferably between 10 mm and 20 mm., strategically positioned along the interior walls to promote the effective movement and tumbling of the absorbent articles as they pass through the separator. The added turbulence created by these structures can improve the separation of organic and inorganic component, as it helps dislodged materials from one another and exposes them to further processing by the paddles on the rotating shaft.

[0101] The underside of the separator comprises a mesh screen (9), wherein the mesh comprises circular holes with a diameter between 20 mm and 60 mm. All holes have the same shape and size. The holes can have a honeycomb pattern or can be placed in regular lines. The shape and dimensions of the mesh play a role in the behavior or the organic matter. The holes must be large enough for the organic matter, which comprises various sizes, to be adequately discharged. Furthermore, larger holes facilitate more tearing, but also possibly more contamination of plastic in the organics. Smaller hoes avoid this, but cause less tearing.

[0102] Figure 3 shows a cross-section of a detail of a device for an embodiment of the invention. The detail shows a cross-section of the inlet conveyor (7), comprising shaftless twin-conveyors. Shaftless screw conveyors can provide improved material handling capabilities. Without a shaft, there is less risk of material buildup or blockages, ensuring a smoother and more continuous flow of absorbent articles into the separator. This design can also facilitate better mixing and transportation of materials, as the absence of a shaft allows for a more uniform distribution of ferees acting on the material as it moves through the conveyor.

[0103] The hopper is positioned at an incline of 30°, enabling the screw conveyor to guide the absorbent articles from a lower container upwards to the inlet of the separator. This inclined design offers several advantages. First, the upward orientation of the screw conveyor utilizes mechanical energy efficiently to transport the absorbent articles from a lower elevation to the higher inlet of the separator. This configuration allows for effective lifting of the materials, ensuring that they are delivered consistently and reliably to the separator without the need for additional lifting mechanisms.Second, the inclined hopper promotes a continuous flow of absorbent articles into the separator. By facilitating the upward movement, the design helps prevent material buildup or clogging in the conveyor system, ensuring smooth operation. The screw conveyor's helical action effectively moves the articles upward while minimizing the risk of damage to the materials, maintaining their integrity during transport.

[0104] The twin-screw conveyors move at a different speed. One conveyor rotates with a speed of 3 rpm, and the other conveyor rotates with a speed of 5 rpm. The difference in rotational speed, creates shear stress that aids in opening the bags wherein absorbent articles are delivered to the hopper. Furthermore, by rotating one conveyor at a slower pace than the other, the input stream can be paced according to the optimal input of the separator. The separator requires a steady input, without overflowing the machine.

[0105] It is clear that the method according to the invention, and its applications, are not limited to the presented examples.

[0106] The present invention is in no way limited to the embodiments described in the examples and / or shown in the figures. On the contrary, methods according to the present invention may be realized in many different ways without departing from the scope of the invention.

Claims

24CLAIMS1. A method for recycling a waste stream comprising predominantly absorbent articles wherein said absorbent articles are separated in at least two separate fractions, wherein one fraction predominantly comprises inorganic matter and one fraction predominantly comprising predominantly organic matter, said method comprising the following steps:• feeding said absorbent articles into a vessel, such as a hopper, wherein said vessel allows the absorbent articles to pass along said conveyor without being shredded;• transporting the unshredded absorbent articles from said vessel to a separator, wherein said separator comprises a rotating shaft positioned along a longitudinal axis of said separator, wherein said rotating shaft comprises a series of paddles positioned along the length of said rotating shaft, said paddles break open the absorbent articles, thereby generating at least an organic fraction and an inorganic fraction; and• physically separating said organic and inorganic fractions based on density, weight and / or size.

2. The method according to claim 1, wherein the vessel is connected to a conveyor or comprises a conveyor, wherein the conveyor is a screw conveyor, preferably a twin-screw conveyor.

3. The method according to claim 1 or 2, wherein the organic matter is discharged at the bottom of the separator.

4. The method according to any of the previous claims, wherein the inorganic fraction is less dense than said organic fraction.

5. The method according to any of the previous claims, wherein during said physically separating, the inorganic fractions follows a vortex path and is discharged through an outlet of said separator.

6. The method according to any of the previous claims, wherein the organic matter is discharged through a screen positioned at the bottom of the separator, wherein said screen has a mesh size between 10 mm and 80 mm.

7. The method according to any of the previous claims, wherein said paddle has a width between 100 and 150 mm and a length between 100 and 200 mm.

8. The method according to any of the previous claims, wherein the rotating shaft has a rotational speed between 300 rpm and 900 rpm.

9. The method according to any of the previous claims, wherein at least two paddles are configured in a different angle than each other.

10. The method according to any of the previous claims, wherein the hopper comprises at least one twin-screw conveyors, wherein both screw conveyors rotate in the opposite direction.

11. The method according to any of the previous claims, wherein each conveyor of the twin-screw conveyors rotates at a different speed, wherein both conveyors rotate with a speed between 3 rpm and 5 rpm.

12. The method according to any of the previous claims, wherein the absorbent articles are diapers and / or wet wipes.

13. The method according to claim 12, wherein said absorbent articles are diapers, more preferably baby and / or children diapers.

14. The method according to any of the previous claims, wherein the input stream is a mixed stream of absorbent articles, wherein said at least half of said stream is comprised of diapers, preferably baby diapers.

15. The method according to any of the previous claims, wherein the lateral side of the separator comprise ribs with a width between 5 and 50 mm and a height between 5 mm and 30 mm.

16. The method according to any of the previous claims, wherein said inorganic matter comprises one or more non-woven sheets, preferably polymer sheets.

17. The method according to any of the previous claims, wherein said organic matter comprises cellulose, organic waste, super absorbent material or a mixture thereof.

18. A recycled stream derived from used and / or unused absorbent articles, preferably diapers, wherein said stream is obtained by means of a separation process of said absorbent article for the purpose of recycling, said stream comprises two physically separated fractions, wherein a first fraction comprises organic material selected from cellulose, organic waste, super absorbent material or a mixture thereof; and wherein a second fraction comprises inorganic matter, said inorganic matter comprises a plurality of non-woven sheets, wherein each non-woven sheet is derived from the sheet material of a separated absorbent article and wherein the surface area of the non-woven sheet is at least 50% of the surface area of the sheet material of the absorbent article prior to separation.

19. The stream according to claim 18, wherein said stream is obtained by the method according to any of the claims 1 to 17.

20. The stream according to claims 18-19, wherein the absorbent articles are diapers, preferably baby diapers.

21. Use of a recycled stream comprising two physically separated fractions, wherein a first fraction comprises organic material selected from cellulose, organic wase, super absorbent material or a mixture thereof; and wherein a second fractioncomprises inorganic matter, said inorganic matter comprises a plurality of nonwoven sheets, wherein each non-woven sheet is derived from the sheet material of a separated absorbent article and wherein the surface area of the non-woven sheet is at least 50% of the surface area of the sheet material of the absorbent article prior to separation.

22. A device for separating and / or recycling absorbent articles in at least two separate fractions, comprising• a hopper, wherein said hopper ends in a separator;• said separator comprises a rotating shaft positioned along a longitudinal axis of said separator, wherein said rotating shaft comprises a series of paddles positioned along the length of said rotating shaft, said paddles break open the absorbent articles, thereby generating at least an organic fraction and an inorganic fraction; and • at least two outlets, for physically separating the obtained fractions.

23. The device according to claim 22, for executing a method according to any of the claims 1 to 17.

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