Patent Description:
Recycling of conventional shoes is a complicated and expensive endeavor, which is therefore most of the time omitted. Thus, old shoes typically end up either in a landfill site or they are incinerated. This results in a loss of valuable raw material and natural resources and furthermore in growing piles of garbage. The reason for the complicated recycling process is mostly based on having up to <NUM> different types of materials almost inseparably glued or stitched together in the production of a conventional shoe.

To address this issue, <CIT> of applicant discloses a shoe, in particular a sports shoe, which comprises an upper, wherein a majority by weight of the upper is made from a thermoplastic base material, and a sole, wherein a majority by weight of the sole is made from the same thermoplastic base material. By providing a shoe with a sole and an upper which - by majority or even entirely - consist of the same base material, the shoe may be easier recycled.

Prior art document <CIT> relates to a used injection-moulded boot in which a boot main body and a lining are integrated. The boot is cleaned, crushed, segregated, and pelletized. The boot main body is a synthetic resin layer injection-moulded by using a boot material, and the lining is a backing cloth laminated integrally on the inner surface of the synthetic resin layer of the boot main body.

Prior art document <CIT> relates to a method for manufacturing an environment-friendly composite material using polyolefin particles and powder rubber that are made from reclaimed plastic and reclaimed rubber as a raw material.

Prior art document <CIT> relates to manufacturing an injection-molded boot which has an inner cover and a shoe sole, wherein at least a lower portion of the inner cover to be bonded to a sole is made from polyester type fiber. A sole material, made of a polyester thermoplastic elastomer, is injection-molded on a bottom surface of the lower portion of the inner cover to integrate the shoe sole and the inner cover. The shoes with which the injection-molding shoes are manufactured were collected/recovered, washed in the state as they were, ground, extrusion molded, pelletized, and regenerated resin is manufactured.

However, recycling such a shoe containing mostly one material or one material class still entails significant difficulties. A typical shoe comprises multiple components serving different functions such as cushioning and support for the sole, a comfortable fit to the foot for the upper, reliable stability for eyelets for laces, etc. In case of a shoe consisting partly or fully of the same material class, the respective material properties are usually achieved by involving different densities. However, recycling such a plurality of different material densities in a way that the result of the recycling process can be used not only for new products with less stringent requirements on the material quality but again for the manufacture of new shoes is still a challenge.

It is therefore the problem underlying the present invention to provide a recycling method and apparatus as well as a recycled shoe which at least partly overcome the above outlined disadvantages of the prior art.

The above-mentioned problem is at least partly solved by the subject matter of independent claim <NUM>. Exemplary embodiments of the invention are defined in the dependent claims.

The present invention provides a method according to claim <NUM> for recycling a shoe. The shoe comprises various components made from the same material class with varying densities. In fact, all of the shoe may be provided from the same material class. The method comprises milling the shoe to obtain a plurality of particles, the particles having different material densities; mixing the particles; applying heat to the mixed particles to obtain a melt of molten particles and extruding the melt. The application of heat to obtain the melt of molten particles can be achieved e.g. by respective heating means. Such heating means can be provided as a separate module to an extrusion device. Alternatively, or additionally, the application of heat to obtain the melt of molten particles can be achieved in the extruding step. In this embodiment, the particles may be conveyed e.g. from a hopper to at least one nozzle of an extrusion device. Such an extrusion device can comprise a conveyor screw which conveys and compresses the particles. This compression may lead to a melting of the particles while they are conveyed to the at least one nozzle.

The claimed invention therefore provides a method to obtain a melt of molten particles which may be used as a raw material for the manufacture of a new shoe. Due to the melting of the particles, the materials of different densities are essentially homogeneously mixed, which allows to provide either directly new high-quality shoe components from the mixture or intermediate products such as pellets, which can then at a later stage be used for the manufacture of shoe components in the same way as new material pellets or the like.

In an embodiment of the invention, the method of recycling a shoe further comprises the step of applying heat and pressure to the shoe, in particular prior to the milling.

In this manner, the shoe, especially a TPU textile of the shoe, is heated and pressed before the milling of the shoe. Said pre-heating and pre-compression help to avoid that the milled or shredded shoe materials, especially the milled textile, gets too fluffy and can afterwards not fed into a hopper of an extruder.

In some embodiments of the present invention, the method of recycling a shoe further comprises the step of adding new material to the mixed particles and / or the melt. The new material may be unrecycled material of the same material class as the shoe.

In this manner, by adding some unrecycled material from the same material class the quality of the mixture is further enhanced leading to the same or almost the same properties as if only new material was used.

Alternatively, or in addition, the new material may also be from a different material class e.g. a chemical optimizer. Such additives may help to further improve the quality and physical and chemical properties of future shoe components made from the recycled material.

The additive may be a reactive system, in particular a bi-functional isocyanate, a trifunctional isocyanate, a bifunctional epoxide or a multifunctional epoxide.

Due to the mechanical forces and heat with milling/shredding, melting and extruding, polymer materials like TPU tend to degrade their molecular structure, resulting in shorter macromolecular chains (= decrease in molecular weight). This in turn will lead to a deterioration of resulting properties, like decreased strength, stiffness, hardness and ductility (e.g. elongation at break). In order to get the molecular weight back up to a level required to achieve suitable application properties, additives may be added to the mixed particles. Such additives may be reactive systems, in particular one of the reactive systems listed above. Adding such additives, in particular a bi-functional isocyanate as a masterbatch at <NUM>-<NUM> weight-%, has proven to lead to improved tensile strength and stiffness, reaching or even exceeding virgin material properties. By choosing a distinct relation of additive, recycled material and virgin TPU (of distinct Shore hardness), properties of the melt and extrudate can be tailored to the application needs. Aforesaid additives especially enable multiple recycling loops.

The single material class comprises a thermoplastic polymer, namely thermoplastic polyurethane, TPU, or polyamide. The majority of weight of the shoe is made from the same material class, in particular wherein at least <NUM>%, preferably at least <NUM>%, more preferably at least <NUM>%, and most preferably at least <NUM>% of the weight of the shoe are made from the same material class.

In some embodiments of the present invention, the method of recycling a shoe further comprises the step of sieving the mix of milled particles and / or the melt. By sieving the mix of milled particles and / or the melt, possible contaminations like e.g. dirt or soil originating from the used shoe to be recycled may be filtered out to result in an intermediate product essentially free from impurities.

Further, in an embodiment not according to the claimed invention, the step of extruding may comprise extruding an intermediate product, in particular pellets, for further thermoplastic processing. This may allow to produce an intermediate product, which may be stored for a period of time or transported to a different location. The stored pellets can then be used in standard thermoplastic production techniques such as injection molding, blow molding etc. In other words, the handling of the recycled material does not or not significantly differ from the handling of a corresponding new raw thermoplastic material for shoe manufacture.

In one embodiment, the intermediate product, in particular the pellets, are further processed in a melt-blowing process to manufacture a melt-blown non-woven fabric of a new shoe. In this context, the intermediate product, in particular the pellets, may be used as a base material to produce the melt-blown non-woven fabric. For example, the intermediate product may be heated and extruded. The extrusion may be executed using a plurality of fine nozzles to produce filaments from the single material class. In this context, the melt may be extruded through a dye comprising a plurality of fine nozzles such that the melt exits the nozzles in the form of filaments with diameters in the range of micrometers or even nanometers. In an embodiment, the filaments are TPU filaments. The TPU can comprise various grades (e.g. 1164D, 1180A). The filaments can be blown by a gas stream, e.g. an air stream, onto a substrate to form a non-woven fabric. The substrate may be planar shaped or three-dimensional shaped, e.g. in the form of a last for producing an upper of a shoe. The substrate also may be a conveyor belt or a substrate layer on such a conveyor belt. The non-woven fabric component may be a reinforcement component. The non-woven fabric component may be a toe box, an internal cage element, an external cage element, or a tongue element (implemented as a single non-woven fabric layer or combined with a different fabric layer). In yet another embodiment, the non-woven fabric layer may form a lasting board or at least a part of it.

The step of extruding comprises extruding an intermediate product adapted for the manufacture of a new shoe without further thermoplastic processing.

This allows to produce an intermediate product of a new shoe, which is a film component, which may be cut and stitched into a desired element of a new shoe. By directly producing such an intermediate product, multiple heat stress due to a further melting process may be omitted. This leads to components for a new shoe of high quality even though originating mostly or even entirely from a recycled shoe.

Alternatively, to extruding an intermediate product in form of a film component, extruding an intermediate product in a melt-blowing process to manufacture a melt-blown non-woven fabric is also applicable. In this manner, the various advantages and processing options provided above when using an intermediate product in form of pellets as source material for the melt-blowing process also apply when extruding the intermediate product directly in a melt-blowing process.

In some embodiments of the present invention, the method of recycling a shoe further comprises the step of producing a new shoe or a component for a new shoe using the extruded melt. The component can comprise a single layer or a composite construction. The component may consist of a film, a non-woven, a knit, a woven, a mesh or a combination thereof. Various single layers of the composite construction of the component can be directly joint by heat, through a mechanical or chemical intertangling process, by an additional adhesive in liquid, film or powder shape or a sewing process.

In an embodiment, the component may comprise a reinforcement element, in particular a toe box, a medial quarter panel, a lateral quarter panel, a tongue, a collar or a heel area. The reinforcement element can be arranged internally or externally on the shoe. The internal surface of a shoe is the surface, adapted to be in contact with a wearers foot. reinforcement element as well as individual layers thereof can be joint for example by heat, through a mechanical or chemical intertangling process or by an additional adhesive in liquid, film or powder shape or a sewing process.

In another embodiment, the component may comprise a lining. The lining can be used in either a full upper construction or one or more partial areas of the upper. The lining can increase a wearing comfort, a thermophysiological properties of the shoe or can be used to cover and/or cushion other elements, in particular uncomfortable elements, of the shoe. The lining as well as individual layers thereof can be joint for example by heat, through a mechanical or chemical intertangling process or by an additional adhesive in liquid, film or powder shape or a sewing process.

In a further embodiment, the component may comprise a strobel board. The strobel board can be manufactured by coating a fabric with one or multiple layers of a film in either an inline or a multi-step process. The strobel board as well as individual layers thereof can be joint for example by heat, through a mechanical or chemical intertangling process or by an additional adhesive in liquid, film or powder shape or a sewing process.

In yet a further embodiment, the component may comprise sockliner. The sockliner can be used to cover a strobel board for increased wearing comfort. The sockliner as well as individual layers thereof can be joint for example by heat, through a mechanical or chemical intertangling process or by an additional adhesive in liquid, film or powder shape or a sewing process.

In another embodiment, the component may comprise a padding and/or cushioning element. The padding and/or cushioning element can be used for example in a collar, a heel or a tongue area of the shoe. The padding and/or cushioning element may comprise a pocket-construction comprising a filling fused between two or multiple layers of a film or foil material. In this respect, the pocket material may comprise a recycled film or foil material, in particular recycled TPU. The filling may comprise shredded or milled material. The padding and/or cushioning element as well as individual layers can be joint for example by heat, through a mechanical or chemical intertangling process or by an additional adhesive in liquid, film or powder shape or a sewing process.

The step of producing may comprise a plurality of extrusion steps with different processing parameters.

The different processing parameters allow to optimize certain components of the shoe. For example, the extrusion may be executed using a fine nozzle to directly produce a yarn from the single material class, which could be further processed e.g. woven or knitted, into an upper of the recycled shoe. Alternatively, extruding the melt may be executed using a plurality of fine nozzles to directly produce filaments from the single material class, which could be further processed, e.g. in a melt blowing process, to form a melt-blown non-woven fabric of a new shoe. The melt may be extruded through a dye comprising a plurality of fine nozzles such that the melt exits the nozzles in the form of filaments with diameters in the range of micrometers or even nanometers. In an embodiment, the filaments are TPU filaments. The TPU can comprise various grades (e.g. 1164D, 1180A). The filaments can be blown by a gas stream, e.g. an air stream, onto a substrate to form a non-woven fabric. The substrate may be planar shaped or three-dimensional shaped, e.g. in the form of a last for producing an upper of a shoe. The substrate also may be a conveyor belt or a substrate layer on such a conveyor belt. The non-woven fabric component may be a reinforcement component. The non-woven fabric component may be a toe box, an internal cage element, an external cage element, or a tongue element (implemented as a single non-woven fabric layer or combined with a different fabric layer). In yet another embodiment, the non-woven fabric layer may form a lasting board or at least a part of it.

It may be noted that additionally, to the usage of post-consumer material by milling and extruding worn shoes, the usage of post-processing waste is possible. This waste can come from various manufacturing processes along the material supply chain, such as scrap or defective material from e.g. yarn spinning, extruding, cutting or assembly processes. The post-processing waste is then processed in the same way as the post-consumer waste prior, during and after the recycling process.

Further aspects of the present invention are defined in the dependent claims.

Aspects of the present invention are described in more detail in the following by reference to the accompanying figures. These figures show:.

In the following, exemplary embodiments of the present invention are described in more detail with reference to a recycling process of a shoe which comprises for the most part materials of the same material class. While specific feature combinations are described in the following with respect to the exemplary embodiments of the present invention, it is to be understood that the disclosure is not limited to such embodiments. In particular, not all features have to be present for realizing the invention, and the embodiments may be modified by combining certain features of one embodiment with one or more features of another embodiment. Moreover, while embodiments of the present invention are illustrated in the following with respect to a recycling process of a shoe, it should be appreciated that the same process can also be used to recycle different pieces of apparel, comprising for the most part the same material class with different material densities.

<FIG> depicts an illustration of a shoe <NUM> as disclosed in <CIT>. The shoe <NUM>, which may in particular be a sports shoe, comprises an upper <NUM>, wherein a majority by weight of the upper <NUM> is made from a thermoplastic base material. Further, the shoe comprises a sole <NUM>, wherein a majority by weight of the sole <NUM> is made from the same thermoplastic base material. By providing shoes with a sole <NUM> and an upper <NUM> which - by majority or even entirely - consist of the same base material, the entire shoe <NUM> may be recycled according to an embodiment of the present invention.

<FIG> schematically depicts an illustration of parts <NUM> of a recycling process of the present invention. In an embodiment the process <NUM> contains the process step <NUM> of milling an old shoe <NUM> by using e.g. rotating cutting units <NUM> or any other suitable device to obtain a plurality of particles <NUM>. The particles <NUM> may have different material densities. The milled particles <NUM> may be collected in a container <NUM>, which may be equipped with one or multiple mixing units such as impellers <NUM> to generate a more or less homogenous mixture <NUM> of the particles <NUM>. In addition, there may be heating means, in order to heat the mixture <NUM> (not shown in <FIG>).

The process <NUM> may further comprise a step of adding <NUM> new material, wherein the new and unrecycled material <NUM> is from the same material class as the majority of materials of the old shoe <NUM>. Adding some unrecycled material <NUM> from the same material class may further improve the quality of the mixture <NUM> leading to the same or almost the same properties as if only new material was used. The new material <NUM> may be also added <NUM> into the container <NUM> and mixed in a step <NUM> with the milled particles <NUM> of the old shoe <NUM> to produce a mixture of particles <NUM>.

Alternatively, or in addition, the process <NUM> may also include the step of adding <NUM> new material, wherein the new material <NUM> is from a different material class e.g. a chemical optimizer. Such additives, for example chain extenders, may help to further improve the quality, i.e. the physical and chemical properties, of future shoe components made from the recycled material. For example, the chain length of the polymers may be increased to affect the stability of any future component made from the recycled material.

Such additives <NUM> may also be added into the container <NUM> and thoroughly mixed <NUM> with the milled particles <NUM>. In some embodiments all three different particles, namely: milled particles <NUM> of recycled shoe material with different densities, new and unrecycled particles <NUM> and new particles from a different material class <NUM> may be mixed <NUM> in the container <NUM> to obtain a homogenous mixture <NUM> thereof. The aggregate of some or even all the different particles may be liquid, gaseous, solid or in any other possible state.

In some embodiments the resulting mixed particles <NUM> may be transferred (not shown) into another container to be either stored, shipped to a different building, factory, company or some other place. In another embodiment the mixed particles <NUM> may be directly further processed in a recycling process <NUM> as shown in <FIG>.

<FIG> schematically depicts an illustration of parts <NUM> of a recycling process of the present invention, which may be a continuation of the process <NUM> illustrated in <FIG>. In an embodiment the homogenous mixture of particles <NUM> may be transferred into a hopper <NUM>, which may direct the mixture of particles <NUM> into an extruder <NUM>. The extruder may comprise a heating system <NUM> to melt the particles and a screw conveyor <NUM> to transport the mixture and / or melt of particles through the extruder <NUM>. The extruder <NUM> may further contain a sieve <NUM> located in an embodiment at the end part of the extruder, at which the mixture of particles should at least be partly or completely melted. By sieving the milled particles and / or the melt, possible contaminations like e.g. dirt or soil originating from the old shoe <NUM> to be recycled, may be filtered out to result in an intermediate product <NUM> essentially free from impurities. Such a sieving process may allow to omit a separate costly cleaning procedure of the old shoe <NUM>. Exchanging and / or cleaning of the sieve <NUM> may be conducted on a regular basis using fully automated processes or may be done manually (not shown in <FIG>).

The intermediate product <NUM> may be further processed in various ways, three of which are also schematically depicted in <FIG>. In the first embodiment, shown as process <NUM>, the melted intermediate product <NUM> may be extruded through a fine nozzle <NUM> to produce a yarn <NUM>. The yarn <NUM> may be rolled onto a yarn bobbin <NUM> or be directly used for further processing of e.g. a fabric <NUM> of an upper <NUM>, laces <NUM> or seams <NUM> of the new shoe <NUM>.

In the second embodiment, shown as process <NUM>, the melted intermediate product <NUM> may be extruded as a film component <NUM> using one or more pressure roller <NUM>. The film component <NUM> may be stored on a roll <NUM> or may be directly used for further processing of e.g. the manufacture of a component of an upper <NUM> of the new shoe <NUM>. The further processing may be performed without additional thermoplastic treatment of the film component <NUM>, which keeps the level of thermal stress of the material of the film component <NUM> as low as possible to ensure a high-quality recycled product.

In a third embodiment, shown as process <NUM>, the melted intermediate product <NUM> may be cut into small pellets <NUM> or the like using a cutting disc, shears <NUM> or any other possible cutting device. The pellets <NUM> may be stored in a container or bag (not shown) to be either shipped to a different building, factory, company or some other place or be directly used for further processing of e.g. a sole <NUM> of the new shoe <NUM> using standard thermoplastic production techniques.

The three different embodiments of processing the melted intermediate product <NUM> shown in <FIG> are only exemplary. This should not limit the scope of the present invention. Furthermore, the splitting of the recycling process into two different parts <NUM> and <NUM> is only for facilitating the description of the present invention. In some embodiments, the two processing parts <NUM>, <NUM> may be completely merged into one process implemented by a single device.

<FIG> depicts a schematic illustration of a cutting pattern <NUM> for a shoe upper. The cutting pattern comprises marked areas <NUM>, <NUM>, <NUM>, in which an arrangement of a reinforcement element manufactured from recycled material in accordance with the present invention may be beneficial. The reinforcement element may for example be used in a toe box <NUM>, a medial and/or lateral quarter panel <NUM>, a tongue (not marked in <FIG>), a collar area (not marked in <FIG>) or a heel area <NUM> of the shoe upper to increase stability of the upper construction, however different areas are also possible. Furthermore, the reinforcement element may increase a wearing comfort for a wearer.

<FIG> depicts a schematic illustration of a cutting patter <NUM> for a shoe upper. The cutting pattern comprises marked areas <NUM>, <NUM>, in which an arrangement of a lining manufactured from recycled material in accordance with the present invention may be beneficial. The lining can be either used in partial areas of an upper construction, such as a rear foot area <NUM> or a front foot area <NUM> or in the full upper construction (not shown in <FIG>). The lining may increase wearing comfort, thermophysiological properties of the shoe. Furthermore, the lining may also be used to cover hard and/or uncomfortable areas on the upper construction.

<FIG> depicts an illustration of a shoe <NUM> in accordance with the present invention. The shoe <NUM> comprises an upper <NUM> and a sole <NUM>. The upper <NUM> comprises a further embodiment of a reinforcement element manufactured from recycled material in accordance with the present invention, which can be arranged on an external or internal surface of the shoe upper. The reinforcement element may also be arranged between various layers of the upper <NUM>. Furthermore, the reinforcement element may comprise a heel support <NUM> and/or a midfoot support <NUM>, however reinforcement of different areas is also possible. The reinforcement element may be manufactured by a molding process to pre-shape or directly fuse the reinforcement element onto the upper <NUM>.

<FIG> depicts a schematic illustration of a strobel board <NUM> in top view <NUM>-a and a side view <NUM>-b. The strobel board <NUM> is produced out of recycled material in accordance with the present invention by coating a fabric <NUM> with one or multiple layers of film, in particular a TPU fabric <NUM> and a TPU coating <NUM>. The coating may be an in line or multi-step process. The fabric <NUM> can hereby consist of a non-woven, a knit, a woven or a mesh or any combination of those materials. A sockliner manufactured from recycled material in accordance with the present invention can be used to cover the strobel board and increase the wearing comfort.

<FIG> depicts a schematic illustration of a cutting pattern <NUM> for a shoe upper. The cutting pattern <NUM> comprises marked areas <NUM>, <NUM>, in which an arrangement of a padding and/or cushioning element <NUM> manufactured from recycled material in accordance with the present invention may be beneficial. The padding and/or cushioning element <NUM> can for example be used in a collar <NUM>, a heel area (not shown in <FIG>) or a tongue <NUM> area, however different areas are also possible. The recycled material may comprise particles of shredded or milled shoes, components of shredded or milled shoes and/or post-processing waste. The post-processing waste can come from various manufacturing processes along the material supply chain, such as scrap or defective material from yarn spinning, extruding, cutting or assembly processes.

Claim 1:
A method for recycling a shoe (<NUM>) having a majority of weight made from a same material class, the shoe (<NUM>) comprising various components made from the same material class with varying densities, the material class being thermoplastic polyurethane (TPU) or polyamide,
the method comprising:
a. milling (<NUM>) the shoe (<NUM>) to obtain a plurality of particles (<NUM>), the particles (<NUM>) having different material densities;
b. mixing (<NUM>) the particles;
c. applying heat (<NUM>) to the mixed particles (<NUM>) to obtain a melt of molten particles; and
d. extruding (<NUM>) the melt,
wherein the step of extruding (<NUM>) comprises extruding an intermediate product (<NUM>) adapted for the manufacture of a new shoe (<NUM>) without further thermoplastic processing, and
wherein the intermediate product is a yarn, a film component or extruded in a melt-blowing process to manufacture a melt-blown non-woven fabric.