Field of disclosure

The present invention lies in the field of footwear recycling technology and relates to a shoe having a sole unit and an upper which can be separated from each other.

Background, prior art

Shoes and in particular running shoes and leisure shoes are typically made of various different components. Most generally, a shoe comprises a sole unit and an upper. While the upper is typically a textile material which may comprise cotton or polymeric materials, the sole unit is made from other, i.e. different, polymeric materials. The sole units of many running and leisure shoes comprise a foamed thermoplastic midsole to provide sufficient cushioning. For avoiding rapid abrasion, the sole unit further often comprises an abrasion resistant outsole. While the sole units are most commonly made from polyurethane or polyamide materials, the textile uppers are preferably made from different materials, in particular polyesters.

Although significant advances have been made in producing ecologically friendly shoes, the vast majority of the materials used for shoe production still originates from fossil sources. Therefore it would be desirable to recycle the materials from used shoes instead of merely disposing them. However, a common problem with recycling of many shoes is that they are made from different materials. For an efficient recycling process thermoplastic materials are most suitable, as these may easily be collected, shredded, melted and reused for a new shoe. However, merely mixing and subsequently melting various different thermoplastic materials together is undesirable, because then the material composition would be different for each recycling step and thus the quality of a shoe manufactured from such recycled material cannot be guaranteed. A first approach known in the prior art is for example disclosed in W02010090923A2. According to this approach, the number of different thermoplastic materials used for a shoe is decreased, even to an extend in which all of a footwear is made from one thermoplastic polymer material.

However, due to specific physical, mechanical and chemical requirements, it would often still be preferred to use different materials at least for certain parts of the shoe, such as the upper and the sole unit but still enable an easy and efficient recycling process.

Summary of disclosure

It is therefore the general object of the present invention to advance the state of the art in shoe technology, in particular in shoe recycling technology, and preferably to overcome the disadvantages of the prior art fully or partly. In advantageous embodiments a shoe is provided which can readily and efficiently be recycled. In further advantageous embodiments, a shoe is provided, which allows to use different materials for upper and sole unit, but can still be efficiently recycled. Furthermore, an easier and more efficient recycling method is provided.

The general object is achieved by the subject-matter of the independent claims. Further advantageous embodiments follow from the dependent claims and the overall disclosure.

A first aspect of the invention relates to a shoe comprising a sole unit and an upper. The upper forms, e.g. defines or delimits, a foot accommodation compartment. Preferably, the upper forms the foot accommodation compartment together with the sole unit. The foot accommodation compartment is typically configured such that the upper together with the sole unit fully circumferentially surrounds the foot of the wearer in the foot accommodation compartment. The upper and the sole unit are connected to each other by a removable connection element. The removable connection element is configured such that it can be removed, particularly completely removed, from the shoe upon which the upper and the sole unit are separated from each other, preferably completely separated from each other. Therefore, the upper and the sole unit are typically connected such with each other by the connection element that they can only be separated from each other when the connection element is removed. The shoe according to the invention therefore allows that the upper and the sole unit can be made from different materials, such as different thermoplastic materials, which can easily be separated from each other by removing the connection element and be recycled separately. In doing so, the recycled sole unit material can be used for producing a new sole and the recycled upper material can be used for a new upper, without changing the material composition of the sole units or uppers.

In some embodiments, the connecting element provides the only connection between the upper and the sole, e.g. the only fixed connection.

Preferably, the upper and the sole unit are fixedly but also releasably connected. That is, the upper and the sole unit cannot be separated and are fixedly connected until the connection element is removed, thereby releasing this connection. Removing the connection element typically directly leads to separation of the sole unit and the upper.

The term “separated from each other” being used in relation of the separation of the upper and the sole unit refers typically to a separation without essentially destructing at least one or all of the parts to be separated, i.e. merely cutting the shoe with a knife or with scissors to directly separate the sole unit and the upper does typically not fall under this term. After separation at least the separated sole unit and optionally the separated upper or at least parts of the upper, remain.

The term “removing the connection element” means that the connection element is completely taken away from the shoe, e.g. it can completely be separated from the remaining parts of the shoe, such as the upper and/or the sole unit. The connection element may in preferred embodiments be, next to the sole unit and the upper, a separate and typically structurally distinct element. However it is also possible in some embodiments that the connection element is an integral part of the upper.

It is generally understood herein that the term “comprising” is interpreted as meaning that it includes those features following this term, but that it does not exclude the presence of other features, as long as they do not render the claim unworkable. On the other hand, if the wording "consist of" is used, then no further features are present in the corresponding apart from the ones following said wording.

A shoe as used herein typically is a sports shoe or leisure shoe. Particularly the shoe is a closed shoe, that is, the upper forms together with the accommodation compartment a closed chamber or pocket for the foot of the wearer. The upper, thus refers typically to the complete upper, i.e. not only a part thereof, such as a vamp, or a heel counter, but the whole part being arranged on top of the sole unit which also form the accommodation compartment.

In some embodiments, the connection element is configured such that it can be removed, in particular completely removed, from the shoe upon which the upper and the sole unit are separated from each other without destroying the sole unit, and optionally the upper, as such, e.g. without destroying their structural integrity as such.

In some embodiments, the sole unit and the upper are connected only by a single connection element.

In some embodiments, the connection element forms a form-locking and/or force locking and/or material bonding connection between the upper and the sole unit. In certain embodiments, the connection element forms a form-locking and/or material bonding connection, between the upper and the sole unit. In certain embodiments, the connection element forms a form-locking and/or force locking connection, between the upper and the sole unit.

The upper may in some embodiments comprise, or consist of, a textile. Thus, the upper may be a fabric. In some embodiments, the upper may comprise or consist of a knit, such as a warp knit, a woven or a non-woven. The sole unit may for example comprise a midsole, such as foamed polymer midsole. The sole unit may in some embodiments comprise an outsole, which preferably has a higher abrasion resistance than the midsole. The sole unit may also comprise other elements, such as a plate, which may preferably be rigid plate, e.g. an elastic and incompressible plate.

5 In some embodiments, the shoe comprises a heel area, a forefoot area and a midfoot area being arranged between the forefoot area and the midfoot area. In some embodiments, the shoe comprises a shoe tip and a heel edge.

Directional indications as used in the present disclosure are to be understood as follows: The longitudinal direction LO of the shoe, is described by an axis from the heel area,0 respectively from the heel edge, to the forefoot region, respectively to the shoe tip, and thus extends along the longitudinal axis of the shoe. Thus the term “extending along/in the longitudinal direction” typically refers to extending towards the shoe tip and the term “extending against the longitudinal direction” typically refers to extending towards the heel edge. The transverse direction TR of the shoe extends transversely to the longitudinal axis 5 and substantially parallel to a base layer of the shoe, or substantially parallel to the ground in the operative state. Thus, the transverse direction runs along a transverse axis of the shoe. In the context of the present invention, the vertical direction V denotes a direction in the operative state in the direction of the foot of the wearer, and thus runs along a vertical axis of the shoe. Thus the term “extending along/in the vertical direction” typically refers to0 extending towards the top layer of the shoe and the term “extending against the vertical direction” typically refers to extending towards the base layer of the shoe. The longitudinal direction, the vertical direction and the transverse direction may all be perpendicular to each other. The lateral side of the shoe is the outer perimeter of the shoe between the heel edge and the shoe tip, which in the worn state rests against the outer instep of the wearer's foot. 5 The indication “horizontal” refers to a plane extending in the longitudinal and the transverse direction and being essentially perpendicular to the vertical direction. The medial side of the shoe, refers to the inner perimeter of the shoe between the heel edge and the shoe tip, which is located opposite the lateral side. Thus, in a pair of worn running shoes, the medial sides of the two running shoes face each other and the lateral sides face away from each other. Furthermore, the shoe may typically along the longitudinal direction be divided into a forefoot area, a heel area and a midfoot area being arranged between the forefoot area and the heel area. For example, the forefoot area extends from the shoe tip against, i.e. opposite, the longitudinal direction to 30-45% of the total length of the shoe in the longitudinal direction. The heel area extends, for example, from the heel edge in the longitudinal direction to 20-30% of the total length of the shoe in the longitudinal direction. The midfoot area extends directly between the heel area and the forefoot area, such that the length in the longitudinal direction of the midfoot area makes up the remaining portion of the total length, particularly from 15-50% of the total length.

In some embodiments, the connection element circumferentially surrounds at least 80%, preferably at least 90%, more preferably 100%, of the periphery of the foot accommodation compartment or of the periphery of the sole unit or of the periphery of the upper. Preferably, the connection element circumferentially surrounds the foot accommodation compartment at an interface between the sole unit and the upper.

In some embodiments, the connection element extends between the sole unit and the upper. Preferably, as seen along the vertical direction, the sole unit is arranged first, followed by the connection element, followed by the upper. In particular embodiments, the connection element is arranged between the midsole of the sole unit and the upper.

In some embodiments, the upper, respectively a portion of the upper, is arranged between the sole unit and the connection element.

In some embodiments, the connection element extends from the heel area of the shoe into the midsole area into the forefoot area. Preferably, the connection element extends from the heel edge on the lateral side through the heel area, the midfoot area and the forefoot area to the shoe tip and from there on the medial side through the forefoot area, the midfoot area and the heel area back to the heel edge. In some embodiments, the connection element is parallel to a surface of the upper. The surface of the upper refers to the outer surface of the upper in the worn state. Thus, in such embodiments, connection element is parallel to a hypothetical line running on and along the surface of the upper. This does however not mean that the connection element must be

5 arranged on the surface of the upper, but it may also be the case that the connection element runs through the upper but still in parallel to the surface of the upper.

In some embodiments, the connection element is a string.

In some embodiments, the sole unit defines or comprises a notch. The notch preferably extends along a peripheral region of the sole unit. The peripheral region of the sole unit0 comprises the lateral and medial delimitation of the sole unit. In particular embodiments, the notch extends circumferentially along the peripheral region of the sole unit.

In certain embodiments, the string and the upper, e.g. at least a portion of the upper, are both accommodated in, and therefore inserted into, the notch. In particular embodiments, the string and the upper are accommodated such in the notch that the upper is arranged 5 between the string and the sole unit, i.e. the notch defined by the sole unit. A notch as described herein has the advantage that the upper can be tightly and readily secured to the sole. The string clamps the upper to the sole unit and the notch provides for a strong and durable connection.

In some embodiments, the string and the notch form together a form-locking and/or force0 locking connection. In particular, the string clamps the upper to the sole unit along the notch.

In some embodiments, the sole unit comprises, or consists of, a bottom unit and a top unit. The top unit is typically arranged on the bottom unit. That is, along the vertical direction, the top unit is arranged on the bottom unit and is thus arranged closer to the foot accommodation compartment than the bottom unit. If the sole unit comprises a midsole, the5 top unit and the bottom unit may in certain embodiments together form the midsole. In some embodiments, the top unit and the bottom unit are formed from separate pieces.

That is the top unit and the bottom unit are in such embodiments not integrally formed.

In some embodiments, the top unit and the bottom unit of the sole unit define together the notch. In certain embodiments, each of the top unit and the bottom unit comprise a central section and a peripheral section circumferentially surrounding the central section, in particular at least horizontally. The central section of the top unit and the central section of the bottom unit may be connected to each other and/or in contact with each other. In contrast, the peripheral section of the top unit and the peripheral section of the bottom unit may in some embodiments be spaced apart from each other, thereby forming the notch.

In some embodiments, the top unit comprises a protruding platform and the bottom unit comprises a recess which corresponds to the protruding platform. The term “corresponds” means that the recess and the protruding platform are configured such that the protruding platform can be inserted into the recess in particular such that they form a form-locking and optionally also a force-locking connection. Further, the contour, i.e. the peripheral shape, of the recess and the peripheral shape of the protruding platform may be the similar or identical. The protruding platform may be inserted into the recess and preferably form a form-locking and optionally also a force-locking connection with the recess.

In some embodiments in which the top unit and the bottom unit each comprise a central section and a peripheral section, the central section of the top unit may be formed by the protruding platform which protrudes from the peripheral section of the top unit. Accordingly, the recess of the bottom unit may form the central section of the bottom unit which is recessed as compared to the peripheral section of the bottom unit.

In alternative embodiments, the bottom unit comprises a protruding platform and the top unit comprises a recess which corresponds to the protruding platform of the bottom unit. Thus, as compared to the above described embodiments, the positions of the recess and the protruding platform are switched. The protruding platform may be inserted into the recess and preferably form a form-locking and optionally also a force-locking connection with the recess.

In some embodiments in which the top unit and the bottom unit each comprise a central section and a peripheral section, the central section of the bottom unit may be formed by the protruding platform which protrudes from the peripheral section of the bottom unit. Accordingly, the recess of the top unit may form the central section of the top unit which is recessed as compared to the peripheral section of the top unit.

The presence of a protruding platform and a corresponding recess improves the connection of the top and bottom unit.

In some embodiments, the protruding platform is configured such that when it is inserted, e.g. completely inserted, into the recess, a portion of the protruding platform projects from the recess. The portion projecting from the recess thus is not inserted within the recess but projects therefrom. In some embodiments, the protruding platform is configured such that when it is inserted, e.g. completely inserted, into the recess, the peripheral section of the top unit and the peripheral section of the bottom unit are spaced apart from each other.

In some embodiments, the top unit and the bottom unit may be material-bonded at the protruding platform and the recess. For example, an adhesive may be applied between the protruding platform and the recess, or the top unit and the bottom unit may in this area be directly material bonded, for example be fused together. It may alternatively or in addition be possible that the top unit and the bottom unit are connected to each other by a forcelocking and/or form-locking connection, for example by a snap-fit connection or by stitching.

In some embodiments, the notch extends from the peripheral region towards the protruding platform. In particular embodiments, the notch extends from the peripheral region up to the protruding platform. In the latter embodiments and when the upper and string are accommodated in the notch, the string secures, in particular clamps, the upper to the protruding platform. In some embodiments, the notch has a curved cross-section, in particular a curved crosssection within the vertical and transversal direction and perpendicular to the longitudinal direction. In particular embodiments, the notch has a cross-section having the shape of a bounded growth curve.

In some embodiments, the protruding platform defines one or more channel structures which extend through the protruding platform. Further, the string may in such embodiments extend through the one or more channel structures, respectively may be arranged in the one or more channel structures. In typical embodiments, the string but not the upper is arranged in the one or more channel structures. Preferably, only the string is arranged within the one or more channel structures. Such a channel structure enables to improve tightening of the string to the sole unit and further enables a firmer and more reliable connection between the upper and the sole unit.

In some embodiments, the protruding platform defines two or more channel structures. In particular, the channel structures may cross each other. For example, two channel structures may for example form together an X-shape. Alternatively, the two channel structures may not cross each other. For example, at least two channels structures may be extend next to each other, in particular in parallel to each other.

Typically, the one or more channel structures penetrate through the protruding platform, in particular from a medial end of the protruding platform to the a lateral end of the protruding platform.

In some embodiments, the upper comprises a plurality of loops, in particular, peripheral loops. Peripheral loops are loops which are arranged at the periphery of the upper. The plurality of loops may for example be loops of a knit or they may be other, separate loops. These loops of the upper may generally be referred to as “upper loops”. In some embodiments, the sole unit comprises a plurality of loops. In some embodiments, the sole unit comprises a rim portion which comprises the plurality of loops. These loops may generally be referred to as “sole unit loops”, particularly as “rim portion loops”.

The rim portion may in certain embodiments comprise, or consists of, a fabric, such as a knit, in particular a warp knit, a woven or a non-woven. It may also be possible that the rim portion is an integral part of the sole unit which may preferably be made of the same material as the rest of the sole unit. In embodiments, in which the rim portion comprises or consists of a fabric, the loops may also consist of the fabric, respectively, they may be formed from the fabric.

The loops of the upper and/or the loops of the sole unit may either be loops formed from a textile material and particularly may be integral to the textile of the upper. Alternatively however, the loops may also be suitable rings, eyelets or other structures which form a loop.

In some general embodiments, the connection element is a string, such as a drawstring. The string may be configured such that it can be removed, in particular completely removed, from the shoe upon which the upper and the sole unit are separated from each other.

The string is typically not stitched, i.e. it is typically not itself stitched to the upper and/or the sole unit. Thus, it does not itself serve as a stich yarn.

In certain embodiments, the string is threaded through at least a portion of, in particular the majority of or even all of, the loops of the upper. Furthermore, the string is threaded through at least a portion of, in particular the majority of or even all of, the loops of the sole unit, in particular of the loops of the rim portion. As the string is threaded both through the loops of the sole unit, in particular the rim portion, and also through the loops of the upper, the sole unit and the upper are connected with each other. In some embodiments, the string is threaded through at least 10, preferably at least 20, more preferably at least 50, more preferably at least 100 loops of the upper and through at least 10, preferably at least 20, more preferably at least 50, more preferably at least 100 loops of the sole unit, in particular of the rim portion.

In some general embodiments, the string is arranged such that it can be removed from the shoe by pulling the string, in particular by pulling the string at a single position of the string. Thereby, the string is preferably removed from all loops of the upper from all loops of the sole unit, in particular from all loops of the rim portion, at once, i.e. during one pulling event, but typically consecutively through the loops. Optionally, the string is arranged such that it can be removed from the shoe by first cutting the string, in particular cutting the string a single time, and pulling the string, particularly at a single position.

In some embodiments, the string extends through the loops of the upper and through the loops of the sole unit, in particular the loops of the rim portion, without forming interloops with the corresponding loops of the upper and with the loops of the sole unit, respectively rim portion. Thus, the string may extend essentially linearly and/or directly through each loop of the upper and each loop of the sole unit, respectively of the rim portion. This does however not mean that the overall arrangement of the string is linear, since the string as a whole may circumferentially surround the foot accommodation compartment, it may as a whole be curved. However each section of the string may essentially extend linearly through a loop of the upper or the sole unit, e.g. the rim portion.

In some embodiments, the string is alternatingly threaded through the loops of the upper and through the loops of the sole unit, particularly of the rim portion. This means, when seen along the string, the string extends through a loop of the upper, then through a loop of the sole unit or rim portion, then again through a loop of the upper, then again through a loop of the sole unit or rim portion, etc.

In some general embodiments, the string essentially extends in a horizontal direction of the shoe. The horizontal direction may be defined by the longitudinal direction and the transverse direction, respectively by a component of the longitudinal direction and a component of the transverse direction. Thus, the horizontal direction may be in a horizontal plane defined by the longitudinal direction and the transverse direction.

In some general embodiments, the string comprises two opposite ends of the string. These opposite ends may typically be separated from each other and connected preferably only by the remaining part of the string.

In some general embodiments, the two opposite ends are arranged in a recess formed by the sole unit and/or by the upper. Such a recess may be defined, respectively delimited by the sole unit and/or by the upper. For example, the recess may be a pocket. Preferably, the two ends in the recess are not accessible, in particular not directly accessible, from the outside. This ensures that the two ends are not freely protruding from the shoe, risking that they may be pulled accidentally.

In some general embodiments, the two ends of the string are attached to the sole unit and/or to the upper by attachment elements, wherein the two ends of the string can be separated from the attachment elements. Suitable attachment elements are structures which allow to attach the strings to the sole unit and/or the upper such that this attachment can be reversed if desired. For example, the attachment means may attach the two ends by form-locking, force-locking and/or material bonding. Suitable attachments means may a glue, a yarn, a knot, a hook-and-loop fastener, a snap fastener, and the like. For detaching the string, it may be cut off from the attachment means or a corresponding form locking connection such as a knot may be released. However, typically the rest of the string, i.e. the portion between the two ends is typically not stitched to the upper and/or sole i.e. it is movable with respect to the upper and the/or the sole unit.

In some general embodiments, the string is a continuous loop, which preferably circumferentially surrounds the foot accommodation compartment, in particular completely. Using a continuous loop structure for the string has the advantage that no loose ends have to be secured. For separating the upper and the sole unit, the continuous loop may be cut a single time at any position and then the cut loop can be pulled, e.g. at a single position, to remove it from the shoe, particularly from the loops of the upper and the loops of the sole unit, particularly of the rim portion, at once, thereby separating the upper and the sole unit.

In some embodiments, the plurality of the loops of the upper and the plurality of loops of the sole unit, particularly of the rim portion, are each formed from a yarn. Furthermore, the string has thickness which is at least 2x, preferably at least 3x, larger than a thickness of the yarn forming the plurality of loops of the upper and the plurality of loops of the sole unit, particularly of the rim portion. A thicker string increases the stability of the connection between the upper and the sole unit. The yarn forming the loops of the upper may be the same yarn which forms the knit or woven of the upper and the yarn forming the loops of the rim portion may be the same yarn which forms the knit or woven of the rim portion.

In some general embodiments, the string consists of one or more yarns. In some embodiments, the string is made from a polymer material or from a metal.

In some embodiments, the connection element is made from a removable polymer, in particular a dissolvable polymer, preferably a photopolymer, a thermo-sensitive polymer or a pH-sensitive soluble polymer. The term “thermo-sensitive polymer” as used herein refers to a polymer which can be removed, in particular dissolved and/or decomposed, at a predetermined temperature, which is typically above room temperature (20 °C). Such an embodiment may also apply for embodiments in which the connection elements is a string. For example, the string may be made of such a dissolvable polymer.

Alternatively, the connection element may be a strip which is made from the removable polymer. For example, the strip may provide a material bonding connection between the upper and the sole. For removing the connection element, conditions are applied which remove, e.g. dissolve or decompose, selectively the dissolvable polymer. For example the shoe is irradiated with light of a specific wave length or it is exposed to a specific pH, such as an acidic or basic pH or to a specific temperature. As the skilled person understands, a photopolymer is a polymer which changes its properties upon irradiation with light of a specific wavelength, in particular light in the LIV-VIS range. Thus, a photopolymer may be used which upon irradiation becomes liquid, fragile, and/or soluble in a specific solvent, such as water and can therefore be rapidly removed from the shoe. Suitable photopolymers are polymers of acrylic acid 2-hydroxyethylester, N,N-dimethyl acrylamide, dipentaerythritol pentaacrylate, N,N-dimethyl-1 ,3-porpylenbisacrylamide or a copolymer of an acrylic acid derivative, such as acrylic acid 2-hydroxyethylester and an alcohol. A pH sensitive polymer is a polymer, which changes its properties upon exposure to a specific pH, such as an acidic pH lower than 7 or a basic pH range higher than 7. Thus, a pH sensitive polymer may be used which upon exposure to a pH change becomes liquid, fragile, and/or soluble in a specific solvent, such as water and can therefore be rapidly removed from the shoe.

In some embodiments, the strip may have in the horizontal plane a width between 0.5 cm and 3 cm, in particular between 0.5 cm and 2 cm.

In some embodiments, the connection element is a thermo-sensitive polymer as described above, wherein the thermo-sensitive polymer is configured such that it can be removed, in particular be decomposed and/or dissolved, at a temperature of 60 °C or more, preferably 65 °C or more, more preferably 70 °C or more. For example, the thermo-sensitive polymer is configured such that it can be removed, in particular be decomposed and/or dissolved, at a temperature of 65 °C to 100 °C, preferably of 70 °C to 95 °C. In such embodiments, the connection element does not dissolve or decompose below these temperatures. Therefore, the connection element is not removed during normal use of the shoe, but can be removed when heated to the indicated temperatures.

For example, the thermo-sensitive polymer may be a thermo-sensitive polymer which is insoluble in a solvent below the temperatures indicated above and becomes soluble at the temperatures indicated above. A suitable solvent may for example be water or an alcohol. As an example, the dissolvable thermo-sensitive polymer may be polyvinyl alcohol, which may in particular be dissolvable in water at 70 °C to 95 °C.

In some embodiments, the thermo-sensitive polymer and the solvent may be chosen such that the thermo-sensitive polymer is dissolved completely in less than 30 min, in particular less than 15 min, in particular less than 10 min in the solvent at the temperature indicated above, i.e. the predetermined temperature.

In certain embodiments, the connection element is made from a removable polymer as described in the embodiments herein above and the connection element is an integral part of the upper. In particular, the majority by weight, i.e. more than 50 wt.% of the upper may be made from the same material as the connection element. In certain embodiments, more than 70 wt.%, in particular more than 80 wt.%, more particular more than 90 wt.% or even all, i.e. 100 wt%, of the upper is made from the same material as the connection element. For example, the upper and the connection element may be made from a thermo-sensitive polymer or a pH-sensitive soluble polymer, In such embodiments, also parts or even all of the upper may be fully removable, respectively dissolvable. For example, the upper and the connection element may be made from polyvinyl alcohol, which may in particular be dissolvable in water at 70 °C to 95 °C.

Suitable materials for the upper may be selected from a polyamide, such as PA-11 , a polyether block amide and a polyester. Suitable materials for the sole may be selected from a polyurethane, such as thermoplastic polyurethane (TPU) or expanded thermoplastic polyurethane (eTPU), a polyamide, such as PA-11 and a polyether block amide. In some embodiments, the upper and the sole unit are made from different materials.

A second aspect of the invention relates to a method for recycling a shoe according to any of the embodiments as described herein, in particular with respect to the first aspect of the invention. The method comprises the step of removing the connection element from the shoe, thereby separating the upper and the sole unit from each other. In a subsequent step, the upper and the sole unit are separately recycled. Preferably, the upper and the sole unit may each be recycled by melting them. In certain embodiments, the separated upper and sole may separately be shredded or granulated before separately melting them.

Im some embodiments, a new upper is produced from the recycled upper and/or a new sole unit is produced from the recycled sole unit. In some embodiments, the connection element of the shoe is a string as described in any of the embodiments herein, in particular with respect to the first aspect of the invention. The string may in an optional preceding step first be cut, in particular only a single time. The string is pulled, in particular at a single position of the string, and thereby the string is removed from all loops of the upper and from all loops of the sole unit, particular of the rim portion which leads to the separation of the sole unit and the upper from each other. Cutting the string in the preceding step is usually performed of the string is or forms a continuous loop as described in some embodiments herein.

In some embodiments, the connection element is made from a thermo-sensitive polymer and removing the connection element from the shoe is performed by heating the shoe to a temperature at which the thermo-sensitive polymer can be removed, in particular dissolved and/or decomposed. For example, the thermo-sensitive polymer can be a thermo-sensitive polymer as described in any of the embodiments herein, in particular with respect to the first aspect of the invention. In certain embodiments, the shoe may be heated to a temperature of 60 °C or more, preferably 65 °C or more, more preferably 70 °C or more. In particular the shoe may be heated to a temperature of 65 °C to 100 °C, preferably of 70 °C to 95 °C. In certain embodiments, heating may be performed in a solvent which is configured such that the thermo-sensitive polymer can be dissolved therein at the predetermined temperature. The solvent may for example be water or an alcohol. In some embodiments, the thermosensitive polymer and the solvent may be chosen such that the thermo-sensitive polymer is dissolved completely in less than 30 min, in particular less than 15 min, in particular less than 10 min in the solvent at the temperature to which the shoe is heated.

Brief description of the figures

The herein described invention will be more fully understood from the detailed description given herein below and the accompanying drawings which should not be considered limiting to the invention described in the appended claims. The drawings are showing:

Fig. 1a a shoe according to an embodiment of the invention; Fig. 1 b a sole unit of a shoe according to an embodiment of the invention;

Fig. 1c an upper of a shoe according to an embodiment of the invention;

Fig. 2 a 2D view of an upper and a rim portion as it can be used in a shoe according to an embodiment of the invention;

Fig. 3 a detailed view of an upper and a rim portion of a sole unit being connected by a string according to an embodiment of the invention;

Fig. 4 a shoe according to another embodiment of the invention;

Fig. 5 a sole unit in a disassembled state as it can be employed in some embodiments of the invention;

Fig. 6 a shoe according to another embodiment of the invention.

Exemplary embodiments

Fig. 1a to c show the separation process of a shoe 1 according to the invention. Shoe 1 comprises a sole unit 2 and an upper 3. Sole unit 2 and upper 3 are connected to each other by connecting element 4 which in this embodiment is a string (see Fig. 3 for the detailed view of such a connection). The string can either have two free opposite ends which may be arranged in recess 8 being formed by sole 2 or the string can be a continuous string which has been cut before removing it from shoe 1. In Fig. 1a, a user wants to separate upper 3 from sole unit 2 to recycle them both individually. This is achieved by removing the string, thereby releasing the connection between upper 3 and sole unit 2 upon which they are separated from each other. In Fig. 1b the separated sole unit 2 having rim portion 5 is shown. As can be better seen in Fig. 3, rim portion 5 may comprise a plurality of loops through which connection element 4 is threaded. Fig. 1c on the other hand shows the separated upper. As can be seen from Fig. 1a and 1 b, the connecting element 4 circumferentially surrounds foot accommodation compartment 9 which is formed by upper

3 and also by sole unit 2.

Fig. 2 shows a flat pattern of upper 3 which is connected to rim portion 5 by connecting element 4. For assembling the shoe, rim portion 5 may for example be attached to a midsole or an insole by material bonding or stitching for generating the corresponding sole unit of a shoe and the shoe as such. The two opposite ends 41 , 42 of the string can for example be arranged in recess 8 defined by sole 2 (see dotted lines in Fig. 1a which indicate the externally not visible recess). For releasing the connection between upper 2 and rim portion 5, a user may pull either one of opposite ends 41 and 42 to remove connection element 4 and separating thereby upper 3 and rim portion 5 of a sole unit.

Fig. 3 shows a detailed view of a connection between rim portion 5 of a sole unit in a shoe and upper 3 of shoe. As can be seen, both upper 3 and the sole unit (in this case the rim portion 5 of the sole unit) comprise a plurality of loops (6, 7), such as rim portion loops 6 and upper loops 7 (only a single loop for the upper and a single loop for the rim portion are referenced for clarity purposes). These loops are arranged in an alternating manner with respect to each other. As can be seen, connecting element 4, in this case a string, is threaded through the plurality of loops of the upper and through the plurality of the loops of the sole unit, i.e. of the rim portion 5. If a user wants to disconnect the upper 2 from the sole unit, a pulling force in the direction of the arrow may be applied, upon which the connecting element is pulled out and removed from the loops of the rim portion and the loops of the upper 2, thereby releasing the sole connection between the upper and the sole unit and separating them from each other.

Fig. 4 shows a shoe 1 according to a different embodiment of the invention. In contrast to the shoe shown in Fig. 1 , the connection element 4 is not a string, but a strip made from a removable polymer, such as a thermo-sensitive polymer. The dashed line indicates that the strip is in this embodiment not visible from the outside. The strip provides a material bonding connection between sole unit 2 and upper 3. Fig. 5 shows a sole unit which comprises top unit 21 and bottom unit 22. In the figure, the sole unit is shown in the disassembled state, i.e. when the top unit is not arranged on the bottom unit. To assemble the sole unit, top unit 21 is rotated along its longitudinal axis by 180° and placed on bottom unit 22. As can be seen, top unit 21 comprises central section 212 and peripheral section 211 which horizontally circumferentially surrounds central section 212. In this embodiment, the peripheral section is formed by protruding platform 213 of top unit 21 , which protrudes from peripheral section 211 of top unit 21. Furthermore, protruding platform 213 defines two channel structures 214 and 215 which in this embodiment cross each other and form an X-shape. When assembling the shoe, a string which can be used as a connection element can extend through these channel structures, thereby enabling a firm and secure connection of the upper at the sole unit. Bottom unit 22 on the other hand also comprises a peripheral section 221 which horizontally circumferentially surrounds central section 222 of bottom unit 22. In this embodiment, central section 222 is formed by recess 223 which is recessed as compared to peripheral section 221 of bottom unit 22. Recess 223 of bottom unit 22 and protruding platform 213 of top unit 21 correspond to each other. That is, they have a similar or identical contour and are configured such that when protruding platform 213 is inserted into recess 22 they form together a form-locking and optionally a force-locking connection.

Fig. 6 shows a cross-section along the transverse and vertical direction of a shoe 1 which comprises a sole unit as it is for example shown in Fig. 5. Bottom unit 22 and top unit 21 define together notch 10 which in this cross section comprises the shape of a bounded growth curve. It should be noted that the gap between the top unit and the bottom unit is drawn in exaggeration for clarity purposes. Top unit 21 comprises peripheral section 211 which is spaced apart from peripheral section 221 of bottom unit 22 and thereby defines notch 10. Furthermore, top unit 21 comprises a central section which in this embodiment is formed as protruding platform 213 which protrudes from the peripheral section 211. Protruding platform 213 is inserted into recess 223 which forms the central section of the bottom unit and which is recessed as compared to the bottom unit’s peripheral region 221. As can be seen, the protruding platform 213 and the recess 223 are configured such that when the protruding platform is inserted completely into recess 223, peripheral regions 211 and 221 are not in contact with each other but spaced apart from each other. In other words, a protruding height of protruding platform 213 is greater than the recessed depth of recess 223. Therefore, notch 10 extends from peripheral region 23 of the sole unit up to protruding platform 223. Upper 3 and connection element 4, which in this embodiment is a string, is arranged within notch 10. It can be seen that upper 3 is in notch 10 arranged between connection element 4 and the sole unit. The connection element thereby clamps the upper to the sole unit.

Reference Signs

1 shoe

2 sole unit

21 top unit

211 peripheral section of top unit

212 central section of top unit

213 protruding platform

214, 215 channel structure

22 bottom unit

221 peripheral section of bottom unit

222 central section of bottom unit

223 recess

23 peripheral region of sole unit

3 upper

4 connection element

41 , 42 opposite ends of string

5 rim portion

6, 7 loops

8 recess

9 foot accommodation compartment

10 notch