METHOD AND DEVICE FOR RECYCLING ROPES.

Abstract

A method for recycling composite ropes, comprising a rope type identification step (S0), and at least one component separation step comprising one or the other of the following steps / S1 / , / S2 / , / S3 / , / S4 / as defined below: / S1 / - a mechanical separation step, / S2 / - a chemical separation step, / S3 / - a thermal separation step, / S4 / - a biological separation step, and a machine or installation for recycling composite ropes.

Description

METHOD AND DEVICE FOR RECYCLING ROPES Technical field The invention relates to methods and devices for recycling ropes. There is particular interest in the recycling of sports racket strings. However, the invention also relates to the recycling of technical ropes such as those used for sailing, climbing, mountaineering, or other sports. The possibility of applying the present invention to musical instrument strings, especially stringed instruments, is also being considered. Background and previous technique Currently, broken or used sports racket strings (tennis, squash, badminton) are thrown in the trash or carelessly disposed of. Provided that, in a previous situation, the ropes were obtained from natural fibers of animal or vegetable origin, they could be considered as naturally biodegradable materials and discarding them in landfills, or even their rejection in them, was not a problem from an environmental perspective. However, it turns out that in more and more cases, these ropes include synthetic components and technical fibers that are not directly biodegradable. Therefore, throwing them away has an unfavorable ecological impact on the environment. Some components can even be considered toxic waste. Public authorities and non-governmental organizations are pushing to manage waste linked to human activity and achieve a truly circular economy and very high recycling rates. The present invention provides a solution that allows many ropes to be recycled. Compendium of the invention For this purpose, a process for recycling composite ropes is proposed, which comprises: - a step to identify the rope type, and at least one component separation step comprising one or the other of the following steps / S1 / , / S2 / , / S3 / , / S4 / as defined below: / S1 / - a mechanical separation step, / S2 / - a chemical separation step, / S3 / - a thermal separation step, / S4 / - a biological separation step. QAHI I n / l Znz / R / YIAI By following these steps, it is possible to recycle strings advantageously, particularly the strings of sports rackets, and thus avoid throwing them in the trash. This method makes it possible to establish a "green circular economy" around the processing of strings, particularly racket strings. The circular economy will allow for the use of polluting waste by transforming its composition into a recoverable resource. According to its composition, each component of the rope is reconverted by reintroducing it into a new production cycle. Therefore, a solution is proposed that avoids throwing ropes in household waste, so that they are not disposed of but recovered; thanks to technical solutions for local recycling or improved waste collection. In various embodiments of the invention related to the system, one and / or the other of the following provisions may be used optionally, taken individually or in combination. According to a relevant report, the strings to be recycled are those used to string sports rackets. We include in this the sports equipment strings used, in particular, but not exclusively, tennis, badminton, and squash. According to another embodiment, the proposed method can be used for technical ropes used for sailing, climbing, mountaineering, or other sports. According to yet another embodiment, the proposed method can be used for the strings of musical instruments, particularly stringed instruments such as violins, cellos, guitars, and double basses. According to a relevant realization, the strings to be recycled are tennis racket strings. The present inventor has discovered that the quantities of composite tennis racket strings are increasing. Furthermore, both professional and experienced amateur players tend to replace their strings before they break or reach the end of their expected lifespan, which significantly increases the quantities consumed and reinforces the interest in the proposed recycling solution. According to one option, tennis racket strings comprise a set of structural fibers with a coating material. The structural fibers comprise aramid and / or polyester and / or polyamide and / or polyolefin and / or polyethylene fibers, and the coating material comprises polyurethane and / or an elastomer. The proposed process thus allows for the treatment of a very wide variety of technical tennis strings or strings for other uses. In this way, most of the usual fiber components are taken into account, and a very high recyclability rate can be achieved. QRm I n / l 7Π7 / E / YΙΛΙ According to one embodiment, for the mechanical separation step (S1) of the fibers and the coating, a stripping step and / or a milling step of the rope yarn is provided. As a result, when the length of the ropes to be treated permits, the rope can be passed through a machine similar to an extruder in which rasps strip the coating material, at least from its periphery. The milling step cuts the rope yarn into small pieces that can then be treated by a chemical, thermal, or biological separation step. According to one embodiment, the chemical separation step involves dissolving the fiber coating in a solvent. This allows for the complete and reliable separation of the technical fibers from the coating material. According to one embodiment, the thermal separation step may include a steam thermolysis step, where the rope strand is heated to over 150°C. Thus, depending on the melting points of the different components, a gradual separation can be achieved by increasing the temperature and recovering first the components with the lowest melting point and finally the components with the highest melting point. According to another embodiment, the biological separation step comprises prolonged contact of the rope strands with biologically active agents, including microalgae and / or enzymes, such that certain components of interest in the rope strands are degraded by these biologically active agents. As a result, even if the required time is longer, this solution is the most energy-efficient for achieving component separation. According to another embodiment, this biological separation step can be used to treat natural gut strings through recycling. The active biological agents, comprising microalgae and / or enzymes, degrade the natural gut strings into basic chemical components that no longer have a problematic impact on the environment. According to one embodiment, the identification step for tennis racket strings consists of making a cross-section, taking a magnified photograph, and analyzing the filament groups to deduce a classification from at least the following types: single multi-strand, multi-core multi-strand, multi-core multi-cover, and single multi-core cover. Based on the resulting identification, the most appropriate separation step or steps can then be selected. According to one implementation, the resulting cross-section can be compared with reference sections, for example, from a smartphone application. QRm I n / l 7Π7 / E / YΙΛΙ The present invention also relates to a machine for recycling composite strings, in particular tennis racket strings, characterized in that it is configured to implement, in part or in its entirety, the method described above. Brief description of the drawings Other aspects, objectives, and advantages of the invention will become apparent upon reading the following description of an embodiment of the invention, given by way of non-limiting example. The invention will also be better understood with reference to the accompanying drawings in which: - Figure 1 shows an illustration of a tennis racket with its stringing, - Figure 2 illustrates various types of rope sections for recycling, - Figure 3 shows a mechanical separation step by peeling, - Figure 4 illustrates a mechanical separation step by grinding, - Figure 5 illustrates a chemical separation step, - Figure 6 illustrates a thermal separation step, - Figure 7 illustrates a biological separation step. Description of the achievements In the different figures, the same references designate identical or similar elements. For the sake of clarity, certain elements are not necessarily shown to scale. Figure 1 partially shows a tennis racket with its stringing. The racket includes a frame 1 and a stringing 2. The stringing passes through holes in the frame. The stringing forms a sieve. Longitudinal sections intersect with transverse sections. To complete the stringing, one or two knots are tied. String 2 can break after a certain amount of wear or if the tension it endures exceeds the tolerable threshold for that type of string. Some users or players replace the strings preventively, as mentioned earlier. To remove the stringing from the frame, the strands of the strings can be removed through the holes in the frame, after cutting one or more sections of the string. Of particular interest is the very common case where the string itself is formed from a set of structural fibers with a covering material. When discussing the composition of the string in more detail, the term “string strand” can also be used to designate a unitary element of the entire string. The string strand may, in certain cases, comprise a solid core. QAHI I n / l Znz / R / YIAI Particular interest is shown in rope strands with an outer diameter between 0.8 mm and 1.6 mm. According to the example, rope strands with an outer diameter between 1 mm and 1.5 mm are specifically considered. With regard to the string threads for tennis rackets, the cross-section of the thread has a diameter of between 1.2 mm and 1.4 mm. However, it should be noted that smaller to larger diameters are also considered in the method of the present invention. The coating material, identified as 4, comprises polyurethane and / or an elastomer. It should be noted that the term “coating” is also sometimes used to refer to the “covering.” The coating material has lower tensile strength than the structural fibers; however, it contributes to the cohesion of the rope yarn. As illustrated in Figure 2, the structure of the rope yarn can be of several types: simple multiple filaments, multiple core multiple filaments, multiple core multiple sheath, single core multiple sheath. Figure 2, example A: solid core, 1 cover Figure 2, example B: solid core, multiple covers Figure 2, example C: multiple filaments, without a core Figure 2, example D: solid multi-core, 1 cover Figure 2, example E: solid multi-core, 1 cover Figure 2, example F: multiple core, multiple ducts Figure 2, example G: multiple core, multiple ducts The structural fibers, generally designated 3 in the figures, comprise aramid and / or polyester and / or polyamide and / or polyolefin and / or polyethylene fibers. The structural fibers used for tennis strings or other types of strings (see the list above) include in particular: - Aramid: Zylon (PBO); Kevlar (PPD-T); Kevlar 49; Black Technora, - Polyester: Pen or Pentex (PEN); polyester (PES), Polyamide: nylon; Polyamide, - Polyolefins: Spectra or Dyneema; HDPE polyethylene, - Titanium: titanium (Ti), - Carbon: carbon fibers, - Elastomer: polybutylene; elastomers (rubbers). ARAMIDES Aramid fibers are known for their excellent impact resistance and are widely used in the manufacture of personal protective equipment (helmets, cut-resistant gloves, bulletproof vests, QAHI I n / l 7P7 / E / YILI etc.). In marine applications, Kevlar® or Technora® products are valued for their excellent strength and low elongation at break (around 3.5%), as well as their remarkable stability under static load (no slippage). In other words, these fibers are very strong (five times stronger than stainless steel), have very little elasticity, and do not stretch over time. Aramid fibers are also used as reinforcements in composite materials, providing good temperature stability to the final products (up to 200 °C depending on the matrix). However, some less positive aspects can be noted: limited UV resistance and significant cost. POLYSTERS Polyester fibers are consumer fibers known for their longevity, UV resistance, and excellent mechanical and chemical resistance. Polyester fiber can be recycled mechanically or chemically, and each method has its advantages and disadvantages. The mechanical method involves recovering plastic bottles and industrial waste, while the chemical process reuses polyester textiles by breaking them down into monomers and then transforming them back into textiles. The polyester recycling method allows for the recreation of materials almost indefinitely: items or fabrics can be recycled many times without losing quality. Furthermore, chemically produced recycled polyester does not contain heavy metals, unlike its counterpart made from freshly extracted petroleum. Polyamides Polyamide fiber, or nylon, is a synthetic fiber classified as a "technical" fiber. It is used in industrial applications of textiles and plastics and is found in a wide range of products requiring high-strength materials. Polyamide is widely used for gears, fittings, and bearings; in the automotive industry for underbody components; and as a material for power tool housings. It is also used in the manufacture of a wide variety of yarns, ropes, filaments, nets, and tire cords, as well as hosiery and knitted garments. There is a wide variety and diverse nuances of industrially available types of polyamides, known by the acronym “PAx.x”. The main strengths of polyamide are its very good mechanical properties (tensile strength, fatigue strength, impact strength, abrasion resistance), as well as good resistance to fuels and oils. On the other hand, it is sensitive to ambient humidity and has relatively limited UV resistance. Despite these drawbacks, polyamides offer an excellent cost-performance ratio. asm in / i zn7 / R / YiAi Currently, polyamides are recycled very little, for reasons related to the chemistry of the polymers (nylon is more difficult to recycle than polyester). POLYOLEFINS Polyethylenes, from the polyolefin family, are part of the so-called "mass-market" plastics, with very high consumption. They are one of the plastics suitable for recycling, although they are often used for low value-added applications. They are subdivided into numerous subcategories, each with specific characteristics (HDPE, LDPE, LDPE, UWMWPE...). High-tenacity polyethylene fibers (commonly called “ultra-high-molecular-weight polyethylene” or UHMWPE) offer the advantages of lightness (density of 0.95 compared to aramid's 1.44) and a high capacity to convert kinetic energy into thermal energy. They are increasingly used in bulletproof vests and other ballistic applications, competing with Kevlar to reduce weight. The polyethylene fibers in the Dyneema™ (from DSM) and Spectra™ (from Honeywell) ranges are characterized by their exceptional strength for minimal weight. In fact, for the same weight, this fiber is up to 15 times stronger than thin steel and 40% stronger than an aramid fiber. Furthermore, these fibers are lighter than water, extremely durable, and resistant to mold, UV rays, and chemicals. As for the disadvantages, one must take into account the low temperature resistance (creep from 90 °C; aramid only degrades at 400 °C), as well as the poor adhesion properties that make composite applications delicate (surface treatment is required). TITANIUM Titanium is a lightweight and strong metal, considered a "noble" metal. It has interesting industrial properties such as resistance to corrosion, erosion, and fire. It is ductile and biocompatible, and also has mechanical properties that allow it to be shaped into thin and lightweight parts. Due to its many qualities, titanium is used in numerous high-value-added fields: medical, aeronautical, petrochemical, and emerging motorsports and leisure activities, where weight reduction is a key performance indicator. Titanium is a metal that combines highly desirable mechanical properties with excellent resistance to corrosive environments, eliminating the need for surface treatments and making it an environmentally friendly material. Furthermore, its density is half that of steel. Titanium is primarily used in alloys in aerospace and for many industrial applications (energy, chemicals, etc.). Given the large amount of production waste, recycling is crucial. The chip removal process is well-organized to recover as much material as possible. It's not uncommon for machining chips to account for up to 90% of the titanium consumed in producing a part. These chips are used as byproducts, such as in the case of the structural fibers of ropes. CARBON Carbon fibers are derived from petroleum and possess extremely interesting properties: rigidity and reliable mechanical stability, ultralight weight, and UV resistance. Provided it is not exposed to impact, the lifespan of carbon fiber is virtually unlimited. Today, carbon fibers are found in many advanced technical applications, where mechanical strength, combined with very low density, are valuable resources: sporting equipment, automobiles, aeronautics, robotics, military equipment, helicopter propellers, wind turbines, drones. One of the most suitable technologies for recycling carbon fibers is pyrolysis. The material is subjected to a high temperature (between 400 °C and 700 °C) to cause the resin to degrade and the components to separate. Depending on the conditions, solid or gaseous byproducts are obtained, which can be used as fuel (energy recovery, see below). The fibers can be recovered at the end of the process for reintroduction into plastics or composites. The main advantage of this technique is the preservation of the mechanical properties of the recycled carbon fibers. METHOD After collection, the recycling process begins with an identification step (denoted SO) of the strings. For tennis racket strings in particular, the identification step involves making a cross-section (using a chisel, cutter, or other sharp tool), after which a magnified photograph is taken, for example, using a smartphone or digital camera. The cross-sectional identification step may include an analysis of the strand groups to determine a classification among at least the following types: single multi-strand, multi-core multi-strand, multi-core multi-sheath, and single multi-core sheath. A cross-sectional reference database can then be consulted on a website to determine the cross-section that most closely matches the previously obtained image. This process can be advantageously supported by a smartphone app. QAHI I n / l Znz / R / YILI Alternatively, the identification step involves reading a reference written on the rope itself. Then, the product identification sheet is consulted on a website to find the type of filament structure and coating. Alternatively, the identification step consists of identifying a representative brand of the rope thread manufacturer. According to yet another embodiment, the color or colors present in the outer coating of the rope yarn can be used to determine the rope type, thus constituting another method for the SO identification step. According to another embodiment, both a representative brand of the manufacturer and a representative color of the type of rope yarn are registered to arrive at an identification of the type of rope yarns to be recycled (step SO). After identification, the process involves selecting one or more of the following steps to separate the yarn from the rope into individual components or small pieces. Preferably, the step of collecting used ropes will reinforce the use of recovery containers, in particular selective containers, each intended to receive a particular type of rope yarn. S1 - mechanical separation step Figure 3 illustrates a stripping and / or grinding step of the rope yarn. When the length of the rope yarn to be processed permits, the rope yarn can be passed through a machine similar to the extruder 36 shown in Figure 3. In this machine 36, the rasps mounted on the rollers 37 are sandwiched between them, and thanks to the rotating motion of the rollers, the rasps peel the coating material at least from the peripheral part of the rope section. The core 21 of the rope is under tension and exits the machine without the peripheral coating 22, which is collected in a container at the outlet of the peeling machine 36. The arrangement is horizontal in the illustrated example. There can be several rasps in series (multiple peeling passes). As for the grinding step, this cuts the rope into small pieces that can then be treated by a chemical, thermal, or biological separation step. For this purpose, as illustrated in Figure 4, a grinder 44 comprises a hopper 46 into which pieces of rope are poured. Two (or more) counter-rotating rollers 47, using a plurality of surface teeth, grind the rope. At the outlet on the lower side, small individual pieces 48 are collected in a container. S2 - chemical separation step Q«m I n / l 7O7 / B / YILI In this case, a solvent is used to completely and reliably separate the technical fibers from the coating material. Trichloroethylene, trichloroethane, dichloromethane, tetrachloroethane, acetone, etc., can be used. Figure 5 illustrates a dissolution apparatus comprising a tank 53 filled with a solution containing the solvent 54 mentioned above. Strands of rope 55 are immersed in it, without any particular restriction on their length (short strands, long strands). After a predetermined time, the action of the solvent solution is considered sufficient and the resulting solution is passed through a sieve; the fibers are retained by the sieve and the coating material dissolved in the solvent solution passes through it. S3 - thermal separation step Figure 6 illustrates equipment with a steam thermolysis stage, where the rope yarn is heated to over 150°. A stationary unit is shown here, but a progressively moving embodiment is also provided. Depending on the melting points of the different components, the components are gradually separated by increasing the temperature. The components with the lowest melting points are collected first, and the components with the highest melting points are collected last. In the example shown, the rope strand 65, without any particular restriction on its length (short strands, long strands), is placed in a furnace 63 and then heated to a predetermined first temperature T1, for example 160 °C, to melt one of the components of the rope strand. The heating 66 can be carried out by various means, such as a burner, infrared lamp paths, an induction furnace, etc. Then the molten part is extracted and the rest is separated. Of course, it is possible to repeat the operation described above with a second predetermined temperature T2, for example 220 °C, to melt another component of the rope thread which is then separated as a molten part. According to one example, following the logic of increasing temperatures, polyolefins can be separated first, then polyesters, then polyurethanes, then polyamides, and so on. Carbon and titanium fibers are the last remaining components. S4 - biological separation step The biological separation stage involves prolonged contact of the rope threads with active biological agents comprising microalgae and / or enzymes. Thus, certain components of interest in rope strands are degraded by these active biological agents. It should be noted that, even if the required time is longer, this solution is the most energy-efficient for achieving component separation. QAm in / ι znz / e / YiAi Furthermore, this biological separation step is also used to treat natural gut strings for recycling. The active biological agents, comprising microalgae and / or enzymes, break down the natural gut strings into basic chemical components that no longer have a negative impact on the environment. Figure 7 illustrates a dissolution apparatus comprising a tank 73 filled with a solution containing gluttonous enzymes 74 and / or microalgae. Strands of rope 75 are immersed in it, without any particular restriction on their length (short strands, long strands). After a predetermined time, the action of the gluttonous enzymes and / or microalgae is considered sufficient and the resulting solution is passed through a sieve; the fibers are retained by the sieve and the coating material dissolved in solution passes through it. Recovery of the separated constituents In addition, there is a step to update the products / components from one of the steps / S1 / to / S4 / . The recovery step includes, for example, incorporating the components into new ropes, and / or into padded technical clothing, and / or into protective technical clothing, and / or into flame-resistant technical clothing. The recovery step may include energy recovery, whereby one or more residues from the separation step mentioned above are burned. Other considerations It should be noted that the various steps and solutions for the identification, separation, and recovery steps are applicable, with the necessary changes, to other types of ropes other than tennis ropes, particularly technical ropes used for sailing, climbing, mountaineering, or other sports, as well as strings for stringed musical instruments.

Claims

1. A method for recycling composite ropes, comprising: - a rope type identification step (SO), and at least one component separation step comprising one or the other of the following steps / S1 / , / S2 / , / S3 / , / S4 / as defined below: / S1 / - a mechanical separation step, / S2 / - a chemical separation step, / S3 / - a thermal separation step, / S4 / - a biological separation step.

2. A method according to claim 1, wherein the strings to be recycled are sports racket strings (2).

3. A method according to claim 2, wherein the strings to be recycled are tennis racket strings.

4. The method of claim 3, wherein the tennis racket strings comprise a set of structural fibers (3) with a coating material (4), wherein the structural fibers comprise aramid and / or polyester and / or polyamide and / or polyolefin and / or polyethylene fibers, and wherein the coating material comprises polyurethane and / or an elastomer.

5. Method according to any one of claims 1 to 4, wherein, in accordance with the mechanical separation step ( / S1 / ) of the fibers and the coating, a stripping step and / or a rope milling step is provided.

6. A method according to any of claims 1 to 4, wherein the chemical separation step ( / S2 / ) comprises dissolving the fiber coating in a solvent.

7. A method according to any one of claims 1 to 4, wherein the thermal separation step ( / S3 / ) comprises a steam thermolysis step, with the rope yarn being heated to more than 150e.

8. A method according to any one of claims 1 to 4, wherein the biological separation step ( / S4 / ) comprises placing the rope yarn in prolonged contact with biologically active agents comprising microalgae and / or enzymes, such that certain components of interest in the rope yarns are degraded by biologically active agents.

9. The method according to any one of claims 1 to 4, wherein the identification step (SO) for tennis racket strings consists of making a cross-section, taking a magnified photograph, and analyzing the filament groups to deduce from them a classification among at least the following types: single multi-filaments, multi-core multi-filaments, multi-core multi-covers, single multi-core covers. QAHI I n / l 7O7 / R / YIAI 10. Method according to any one of claims 1 to 4, wherein a step is provided for updating the products / components of one of steps / S1 / to / S4 / , wherein the updating step comprises incorporating the components into new ropes, and / or into padded technical clothing, and / or into protective technical clothing, and / or into flame-resistant technical clothing.

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