Process for recovering constituent materials from a composite product containing uncured rubber and reinforcement materials

Abstract

The present invention provides a process for recovering constituent materials from a composite product, the process comprising: a) providing a composite product comprising a plurality of constituent materials, said constituent materials comprising uncured rubber and a reinforcing material selected from fibers and / or metal; b) providing one or more standardized sheets of the composite product, each standardized sheet having a maximum thickness of 125 mm or less; and c) spraying pressurized water at a pressure of 500 bar or less onto one or more surfaces of the standardized sheet, thereby peeling the uncured rubber from the reinforcing material and resulting in a mixture of uncured rubber fibers and reinforcing material.

Description

[Technical field]

[0001] The present invention relates to a process for recovering constituent materials from composite products, the process being suitable for recovering uncured rubber in a reusable form, allowing it to be resynthesized as virgin material.

[0002] The process of the present invention can be used, inter alia, to recover uncured rubber, metals, and fibers from composite products in a form in which each of these constituent materials can be reused. [Background technology]

[0003] Complex waste products containing cured (vulcanized) rubber, such as post-consumer tires, can be recycled through the use of mechanical crushing equipment such as shredders, granulators, and fine powder mills.

[0004] During the rubber product manufacturing process, waste material is generated that may include uncured or "green" rubber. For example, tires are made from a substrate containing polymers and metal and fiber reinforcements. Metal beads and fiber cords are used in multiple layers to reinforce the sidewalls. At any point in the manufacturing process, the substrate may be rejected. Rejection may be due to assembly defects, thickness or content variations, or any other such quality control failure or defect. Rejected parts are typically packaged or packed into pallet boxes and sent for processing or disposal.

[0005] Conventional processes such as shredding and granulation, as used for cured post-consumer tires, cannot be used to treat these substrates unless significant amounts of anti-adhesive additives are used. Without such additives, the uncured rubber will stick to surfaces or to itself. When exposed to metal blades, the uncured rubber will stick to the blades and accumulate, forming clumpy balls. Continued exposure to sources of friction will cause the uncured rubber to heat up, leading to a fire risk. Suitable additives such as talc, chalk, and metal soaps are known, but the addition of such additives significantly affects the suitability of the uncured rubber for reprocessing as virgin material.

[0006] Generally, the presence of metals and fibers in the substrate makes it impossible to recover the uncured rubber and recombine it as virgin material. The rubber attached to the metals and fibers cannot be easily removed due to the very sticky nature of uncured rubber. If these materials (uncured rubber, metal, and fibers) are to be reused, separation of the constituent materials is essential.

[0007] Because of these difficulties, waste substrates containing uncured rubber are typically subjected to incineration.

[0008] Tire production is associated with a high carbon footprint. It would therefore be desirable to recover uncured rubber and reuse it as virgin material in primary applications to offset the carbon footprint and offset the emissions generated. Reusing rejected rubber substrates would also reduce the demand for increasing rubber plantations to replace forest areas. Additionally, the demand for petroleum-derived products such as synthetic rubber polymers and carbon black could be advantageously reduced.

[0009] The size of the waste stream is approximately 10% of the total annual tire production. Approximately 40 million tons of natural rubber, synthetic rubber and carbon black become waste every year. It is clear that achieving a more efficient use of the waste stream would be of great environmental benefit.

[0010] However, any suitable waste management solution would need to be capable of operating on a large industrial scale with significant throughput volumes.

[0011] Besides the mechanical processing route, attempts have been made, on a small scale and only non-commercially viable basis, such as peeling individual wires from the rubber sheet.

[0012] Non-mechanical comminution processes, such as the use of water jets, are known and have been used, inter alia, to recycle post-consumer products, including vulcanised rubber.

[0013] JP2005046758A describes a method for crushing rubber tires with a water jet, in which the water jet is ejected from a nozzle having a diameter of φ1.0 mm to φ5.0 mm at a pressure of 70 MPa to 175 MPa and a flow rate of 30 L / min or more.

[0014] US5944925A describes retreading of tires by removing the worn tread and fitting a new tread. This document provides a process for treating the vulcanized rubber surface before bonding, in which a surface roughness is created and degraded surface particles are removed by applying a high pressure fluid jet.

[0015] ITMI20081559A1 details a process for recycling post-consumer tires. The process uses water jet technology to dismantle the tires, obtaining rubber powder, steel, and nylon fibers from the destruction of the tires.

[0016] RU 2114731 describes a process of performing water jet cutting of worn rubber automobile tires into rubber crumb. When cutting metal cord tires, the rubber is separated from the metal cord, which can also be used as a recyclable material or as scrap metal.

[0017] WO2011 / 158002A1 provides a method for dismantling used vehicle tracks into usable components. The method uses a high pressure water jet to create a rubber crumb slurry which may also contain fibrous components.

[0018] WO2012 / 127510 uses a water jet to process vulcanised rubber. Pressures of 1000 bar to 4000 bar are described, with water flows of 8 L / min to 16 L / min.

[0019] WO2013 / 105553A1 describes pulverizing a rubber material to a particle size of, for example, 0.5 to 3 mm, and using a water jet to remove impurities from the rubber powder.

[0020] EP 3815867 A1 describes recycling thermosetting polymer objects by a process which involves pulverizing the thermosetting polymer using water jet technology and then drying the pulverized thermosetting polymer.

[0021] RU2746836C1 describes the separation of unvulcanized rubber from the metal cord of waste rubberized metal cords. The method uses the action of water under high pressure, which is said to break the bond between the rubber and the metal of the rubberized steel cord. Specifically, an inflow material is provided, which is scrap / waste rubberized metal cord (unvulcanized rubber compound), which is placed in a working chamber on a stainless steel grid and then impacted with water jets having a pressure power of 500 bar to 3000 bar and a flow rate of 15 L / min or more. It is stated that breaking the integrity of the inflow material leads to a complete separation of the rubber.

[0022] However, a need remains for a process that allows all of the individual materials to be recovered from the uncured rubber composite product in a form suitable for reuse. Summary of the Invention

[0023] The present invention provides a process for recovering constituent materials from a composite product, the process comprising: a) providing a composite product comprising a plurality of components, said components comprising uncured rubber and a reinforcing material selected from fiber and / or metal; b) providing one or more standardized sheets of the composite product, each standardized sheet having a maximum thickness of 125 mm or less, preferably 110 mm or less, more preferably 100 mm or less; c) spraying pressurized water at a pressure of up to 500 bar onto one or more surfaces of the standardized sheet, thereby stripping the uncured rubber from the reinforcing material, resulting in a mixture of uncured rubber fibers and reinforcing material; Includes.

[0024] The process of the present invention is an industrially viable process by which uncured rubber and reinforcing materials selected from fibers and / or metals can be taken from what is in the form of an interlocking composite material and made into a mixture separated from one another, the components of which can then be reused individually.

[0025] Advantageously, the uncured rubber is obtained in a form that is free of contamination and suitable for recomposition and reuse, and even more advantageously, the reinforcing materials (metal and / or fibers) are obtained in a form that is free of damage and suitable for reuse.

[0026] In particular, it has been determined that by preparing the composite product in a standardized sheet having a maximum thickness of 125 mm, such as 110 mm or less, and preferably a maximum thickness of 100 mm, non-aggressive conditions can be used to strip the uncured rubber from the metal and / or fibers, i.e., damage to the metal and / or fibers is avoided.

[0027] This is in contrast to previous processes in which water is used at very high pressure and therefore acts to cut through the product causing damage to at least some of the constituent materials. It will be appreciated that if the fibers are torn they cannot be reused and if the metal is cut harmful metal fragments may be exposed.

[0028] It is further beneficial to avoid aggressive conditions in terms of preventing contamination of the rubber. Aggressive conditions that cut or tear the material result in contamination of the rubber with metal and / or fiber fragments. It would clearly be advantageous to consider reusing the rubber such that such contamination is avoided.

[0029] By standardizing the sheet so that it is relatively thin, and preferably substantially uniform in thickness, it has been found that pressurized water up to 500 bar is effective in stripping the rubber from the reinforcing material, beneficially causing the rubber to form a powder and / or granules that can be easily removed and handled.

[0030] It has been determined that water should not be used in step c) at a pressure above 500 bar, as this leads to damage to the reinforcing material, especially the fiber material. In one embodiment, water is used at a pressure below 500 bar. In one embodiment, water is used at a pressure of 110 bar to 500 bar, or 120 bar to 500 bar, preferably 130 bar to 500 bar. In a preferred embodiment, water may be used at a pressure of 130 bar to 450 bar, for example 200 bar to 400 bar, such as 150 bar to 400 bar.

[0031] In one embodiment, the reinforcing material is metal and the pressure used is from 130 bar to 500 bar, for example from 200 bar to 400 bar, such as from 150 bar to 450 bar or from 300 bar to 400 bar, for example about 375 bar. It has been determined that above 500 bar the metal wire is forcefully peeled away and the rubber is not completely removed from the resulting metal wire strip.

[0032] In one embodiment, the reinforcing material is fibre and the pressure used is from 130 bar to 400 bar, or from 200 bar to 400 bar, for example from 225 bar to 375 bar, such as from 275 bar to 350 bar, for example around 340 bar.

[0033] In the present invention, a constant force per unit area can be applied in the jetting step, for example using a nozzle that directs pressurized water onto the surface. The process of the present invention is controlled and reproducible on an industrial scale. By implementing sheet normalization, the force applied by the water jet is uniform across the entire sheet.

[0034] The pressures used in step c) of the process of the present invention are of a similar order of magnitude to power washing, rather than the much higher waterjet cutting pressures, which often involve pressures of at least about 10,000 psi (689 bar), usually in excess of 20,000 psi (1379 bar), for example about 60,000 psi (4136 bar) or more.

[0035] In one embodiment of the invention, the process further comprises one or more, for example two or more, of the following steps: d) separating the metal from the mixture, for example by using a magnet; and / or e) separating the fibers from the mixture, for example by using filters or screens or by suction or flotation; and / or f) Separating the uncured rubber from the mixture, e.g. the rubber may be removed.

[0036] It will be appreciated that steps d), e) and f) may be performed in any order.

[0037] In one embodiment, steps d) and e) are performed (in either order), leaving the uncured rubber as the final isolated product.

[0038] In a preferred embodiment, the process results in three separate products: (i) uncured rubber, (ii) metal, and (iii) fibers, each of which is suitable for reuse.

[0039] The uncured rubber may optionally be dried, for example using a dewatering drying conveyor. The uncured rubber may optionally be subjected to rubber conditioning. In one embodiment, the uncured rubber is subsequently recompounded. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] [Detailed Description of the Invention] <Composite product> The process of the invention makes it possible to recover constituent materials from a composite product, which comprises uncured rubber and a reinforcing material selected from fibers and / or metals.

[0041] The fibers may be synthetic fiber materials. In one embodiment, the composite product includes fibers selected from rayon, nylon, polyester, and aramid, and combinations thereof. The fibers may be in the form of, for example, strips, or strands, or fibers.

[0042] The metal may be an alloy. In one embodiment, the composite product includes a metal that is a steel, such as stainless steel. The steel may be in the form of, for example, a steel cord and / or a steel wire.

[0043] The composite product may be a waste product generated during a rubber product manufacturing process. In one embodiment, the composite product is a waste product from a tire manufacturing process.

[0044] As those skilled in the art know, during the tire building process, individual components are created which are subsequently assembled into a product containing fibrous and metallic reinforcing materials along with uncured rubber.

[0045] One product formed during the tire manufacturing process includes a fibrous friction material in the form of a layer made from nylon fibers, such as PA6 fibers, aligned and coated with uncured rubber. The fibrous strands may be coated with an adhesion promoter.

[0046] Another product formed during the tire manufacturing process is metallic friction materials that include steel wires encapsulated in uncured rubber. These metallic friction materials may be fabricated, for example, as rings that become tire bead reinforcements or as flat sheets that are incorporated into the body of the tire.

[0047] The additional products can then be assembled to form the body of the tire, which will contain both fiber and metal reinforcements and uncured rubber.

[0048] Thus, waste products from a tire manufacturing process can be any such products that have been rejected due to, for example, assembly defects, thickness or content variations, or any other such quality control defects or failures. These waste products are not the same as used tires, in that the rubber is uncured (unvulcanized).

[0049] Those skilled in the art will recognize that different composite products may have a variety of different compositions. While the entire tire may contain relatively low amounts of fiber and metal as reinforcing materials, for example, as little as 5% fiber and 12% metal by weight, due to the presence of a tread or butyl liner, the individual components used to make the tire may have much higher percentages of fiber or metal reinforcing materials. For example, a metal friction material may have a metal content as high as 90% by weight, and a fibrous friction material may have a fiber content as high as 80% by weight. Essentially, these friction material products include reinforcing materials along with a rubber coating to promote adhesion.

[0050] The composite product provided in step a) may, for example, comprise 5 wt.% or more, or 10 wt.% or more, or 20 wt.% or more of uncured rubber. In one embodiment, the amount of uncured rubber may range from 5 wt.% to 90 wt.%.

[0051] The composite product provided in step a) may for example comprise 10% by weight or more, or 15% by weight or more, or 20% by weight or more of reinforcing material, which may be fibre and / or metal, In one embodiment the amount of fibre and / or metal reinforcing material may range from 10% by weight to 90% by weight.

[0052] The composite product may optionally contain additional materials other than the uncured rubber and reinforcing materials, particularly those of ordinary skill in the art will be aware of chemicals known in the art to be contained in tires and that are commonly compounded with uncured rubber.

[0053] For example, additional materials that may be present in the composite product include one or more of a filler (e.g., a filler selected from carbon black, silica, carbon, and chalk, and combinations thereof), a plasticizer, a vulcanizing agent (e.g., sulfur and / or zinc oxide), and an anti-aging agent.

[0054] As those skilled in the art will appreciate, these additional materials are typically compounded with the uncured rubber, and therefore, for purposes of the present invention, recovery of the uncured rubber, when such additional materials are present, refers to recovering the uncured rubber in a compounded form including any such additional materials, and thus, the uncured rubber is recovered in a form in which it can be cured.

[0055] <Sheet of composite product> To ensure the effectiveness of the process, the starting product must be specified to ensure efficient removal of uncured rubber from the reinforcement material.

[0056] The process therefore comprises a step b) in which one or more standardised sheets of the composite product are prepared, each having a maximum thickness of less than or equal to 100 mm.

[0057] Thus, a sheet of the composite product is required.

[0058] If in step a) the composite product is not provided in the form of a sheet, for example in the form of a veil, then step b) comprises: bi) cutting the composite product into the form of one or more cut sheets, and then b-ii) performing a thickness normalization on each cut sheet such that each sheet has a thickness of 125 mm or less, e.g. 110 mm or less, preferably 100 mm or less.

[0059] If in step a) the composite product is already provided in the form of a sheet, step b) comprises: b-0) Carrying out thickness standardization so that each sheet has a thickness of 125 mm or less, for example 110 mm or less, preferably 100 mm or less.

[0060] If step bi) is required, cutting may be accomplished in any suitable manner, for example high pressure water jet cutting may be used, in a preferred embodiment a shear guillotine knife may be used, low speed band saws may also be considered for use.

[0061] The cutting may be performed using a shear cutting system. The composite product, for example in the form of a bale, may be placed on a conveyor and fed to a cutting head. The cutting head then removes a sheet from a leading edge of the composite product. This cutting step of removing a sheet is then repeated as necessary to obtain one or more sheets.

[0062] Once the sheet is obtained, it may optionally be cut again (eg, cut in half) to reduce the thickness of the sheet.

[0063] The (each) cut sheet as obtained in step bi) may for example be up to about 500 mm thick, for example between 150 mm and 400 mm thick, or between 175 mm and 300 mm thick, for example about 200 mm thick.

[0064] Those skilled in the art will recognize that the sheets may be of any length and width, the only limitation in this regard being having suitable sized equipment to handle the sheets, and in particular to perform the thickness normalization step, and therefore the present invention is not limited to sheets having any particular dimensions in terms of width and length.

[0065] In one embodiment the cut sheets have a length of 5m or less, such as 3m or less or 2m or less, and may for example have a width of 0.1m to 2.5m, or 0.2m to 2m.

[0066] In one embodiment the cut sheets have a length of 5m or less, such as 3m or less or 2m or less, and may for example have a width of 0.1m to 2.5m, or 0.2m to 2m.

[0067] The width and length may be approximately the same so that the cross section of the sheet is substantially square, although this is not essential: rectangular shapes can also be easily processed.

[0068] <Thickness standardization> The composite product sheet (either provided in step a) or obtained in step bi) is subjected to a thickness standardization.

[0069] The thickness standardization step ensures that each sheet has a maximum thickness of 125 mm or less, preferably 110 mm or less, and more preferably 100 mm or less.

[0070] The thickness normalization step involves applying pressure to each sheet. Generally, techniques that involve applying weight to a metal plate as a force are useful.

[0071] Any suitable apparatus may be used in this regard, and those skilled in the art will be aware of pressing equipment such as calendar presses, belt presses, or hydraulic presses, any of which may be suitably used.

[0072] In general, any equipment or technique that will reduce the thickness of the sheet can be used, what is important is that the sheet has a maximum thickness not exceeding 125 mm, preferably a maximum thickness of 110 mm or less, and more preferably a maximum thickness of 100 mm or less.

[0073] A person skilled in the art will also know techniques that allow achieving the thickness of the sheet. In addition, measuring the thickness of the sheet to check that it meets the requirements can be easily achieved using standard equipment such as gauges or calipers.

[0074] In one embodiment, the desired thickness is achieved by a physical stop system. A press die tool has a die cavity into which the sheet can be placed between an upper plate and a lower plate. The tool includes a protrusion located between the upper plate and the lower plate, which acts as a stop for the upper plate to move towards the lower plate, thus inhibiting the press from closing completely. In this way, the height to which the protrusion extends above the lower plate controls the thickness of the pressed sheet. The protrusion can be a single dowel or lug, or multiple spaced dowels or lugs can be used, or a continuous protrusion can extend all the way around the cavity.

[0075] In another embodiment, a proximity switch can be used that is configured to be activated once the correct thickness is achieved, thus stopping the closure mechanism at that time.

[0076] Proximity switches may be particularly suitable for slower closing press systems, while for faster closing press systems a physical stop system may be more suitable.

[0077] In one embodiment, pressure is applied for a period of 30 seconds or more, for example 30 seconds to 10 minutes, preferably 30 seconds to 5 minutes.

[0078] Those skilled in the art will recognize that the temperature should not exceed 90° C. to ensure that the rubber remains uncured.

[0079] The process can be automated, with a preset pressure to be applied and the duration for which the pressure is applied. The process can be monitored in an automated fashion.

[0080] An automatic adjustment can also be programmed so that the pressure automatically increases if the desired preset thickness is not achieved.

[0081] The sheet expands as the thickness is reduced: the higher the rubber content, the greater the expansion.

[0082] Generally, a press force of about 500 tonnes per square meter is likely to be suitable, although those skilled in the art will recognize that this can be adjusted as required.

[0083] In one embodiment, the press is at least a 50 ton press, for example at least a 100 ton press, such as a 500 ton press or a 1000 ton press.

[0084] In one embodiment, the platen is at least one meter square.

[0085] The sheets are thickness standardized in one embodiment to have a maximum thickness of 110 mm or less, preferably 100 mm or less.

[0086] For example, the sheet may be thickness standardized, for example to have a maximum thickness of 80 mm or less, such as 70 mm or less, preferably 60 mm or less, such as 50 mm or less.

[0087] In a preferred embodiment, the sheet is thickness standardized to have a maximum thickness of 40 mm or less, such as 30 mm or less.

[0088] To ensure that the sheet is easily handled it may be desirable to ensure a thickness of at least 3 mm, in one embodiment the sheet has a thickness of 3 mm to 100 mm, for example 3 mm to 60 mm, preferably 5 mm to 40 mm.

[0089] The application of a constant force per unit area in the jetting step c) allows for uniform thickness of the sheet, thereby allowing for uniform rubber removal.

[0090] In one embodiment, all sheets of step b) are thickness standardized so that they all have substantially the same maximum thickness (±5 mm, preferably ±3 mm maximum thickness).

[0091] By having the sheets have a standardized thickness, the flow and pressure across the sheet is as uniform as possible, aiding in consistent results in terms of clean separation from the reinforcing material for all sheets.

[0092] An added benefit of the thickness normalization step by applying pressure is that it creates a flat surface for each sheet, so the water jet flow in step c) is more effective in peeling the uncured rubber from the reinforcing material since there are no hidden or hard to reach areas.

[0093] <Optional preheating> Once the sheet has been standardized in thickness, it may optionally be preheated prior to the injection of pressurized water in step c).

[0094] To avoid curing the unvulcanized rubber, it is preferred that the sheet not be heated to a temperature above 90°C.

[0095] In one embodiment, the sheet resulting from step b) is preheated to a temperature of between 40°C and 90°C.

[0096] In a preferred embodiment, the sheet resulting from step b) is pre-heated prior to step c) to a temperature of 40° C. to 80° C., or 40° C. to 70° C., more preferably to a temperature of 40° C. to 60° C., such as 40° C. to 50° C. or 40° C. to 45° C.

[0097] Preheating may be performed using any suitable equipment, for example a heating tunnel or oven. Those skilled in the art will know for example stenter ovens and will know that such ovens can be suitably used, which use a conveyor belt to move the material. Thus, the conveyor belt carrying the sheet passes under a number of plenums blowing hot air. The plenums are perpendicular to the movement of the sheet on the conveyor, and the sheet is heated by the hot air as it passes through.

[0098] <Pressurized water injection> In step c) pressurized water, at a pressure up to 500 bar, is sprayed onto the surface of the standardized sheet.

[0099] This step may be carried out in a power washing station, which may optionally be a multi-nozzle station, which may have any suitable number of nozzles, which may be 2 or 3 or 4 or more, for example 20 or more, such as 10 or more, or 25 or more, or 50 or more.

[0100] The pressurized water is suitably sprayed onto the sheet using one or more nozzles. The nozzles may be fixed or may be movable, for example by vibration. The latter may be preferred, as it allows achieving an increased coverage of the pressurized water on the surface of the sheet.

[0101] The nozzles may be located above and / or below the sheet, in one embodiment there are nozzles both above and below the sheet.

[0102] In one preferred embodiment, there are vibrating nozzles both above and below the sheet, which direct pressurized water onto both the upper and lower surfaces of the sheet and across its surface area.

[0103] Those skilled in the art will recognize that any given nozzle has a coverage area over which it directs water. Thus, one skilled in the art can design an array of stationary nozzles suitably spaced apart so that the entire surface area of ​​the sheet is impinged with pressurized water when the nozzles spray the pressurized water. Alternatively, one skilled in the art can design an array of vibrating nozzles suitably spaced apart so that the entire surface area of ​​the sheet is impinged with pressurized water over the course of a vibration cycle while the nozzles are spraying the pressurized water.

[0104] In one embodiment, in step c), the pressurized water is directed over the entire upper and lower surfaces of the sheet. However, it is not necessary to achieve 100% coverage, and good results can be achieved, for example, by directing the pressurized water over 50% or more, in particular over 75%, or over 80%, or over 90% of the surface area of ​​the sheet.

[0105] Examples of nozzle heads that can be used include pencil jets, cleaning lances, fan heads, and oscillating heads (internal or external oscillating).

[0106] It has been determined that in step c) water should not be used at a pressure above 500 bar as this leads to damage to the fibers. In one embodiment water is used at a pressure below 500 bar. In one embodiment water is used at a pressure between 110 bar and 500 bar, or between 120 bar and 500 bar.

[0107] In a preferred embodiment, water is used at a pressure of 130 to 500 bar, or 130 to 495 bar. In an embodiment, water is used at a pressure of 130 to 490 bar, or 130 to 482 bar, or 130 to 475 bar. In an embodiment, water is used at a pressure of 130 to 450 bar, or 130 to 400 bar, for example 130 to 350 bar. In an embodiment, water is used at a pressure of 150 to 450 bar, or 150 to 400 bar, for example 200 to 400 bar, or 225 to 375 bar.

[0108] Also, one skilled in the art will recognize that the distance of the nozzle from the surface of the sheet can be varied as desired to affect the force of the water smear (as a function of height).

[0109] In one embodiment, the distance of the water jet nozzle from the substrate is from 10 mm to 200 mm, or from 15 mm to 200 mm, or from 20 mm to 200 mm, such as from 30 mm to 150 mm.

[0110] Preferably the distance is from 40mm to 100mm, more preferably from 40mm to 90mm, for example from 40mm to 80mm, or from 60mm to 80mm, especially from 70mm to 80mm. These distances have been found to give the best results in terms of cleaning the rubber over a large area.

[0111] Typically, the deflection of the water jet onto the open wire mesh conveyor may be seen to occur at a distance of 200 mm from the substrate. Thus, in one embodiment, the distance is less than 200 mm, for example 30 mm to 150 mm, in particular 40 mm to 100 mm.

[0112] The angle of the nozzle relative to the substrate can also be varied. In one embodiment, the angle is from 60° to 90°, such as from 62° to 88°, or from 70° to 88°, where 90° is a perfect orthogonal direction. In one embodiment, the angle of the nozzle relative to the substrate is about 88°.

[0113] In this regard, it has been determined that angling the jet stream within the range of 60° to 90°, such as within the range of 62° to 88°, or 70° to 88°, can significantly increase the area over which delamination of the uncured rubber occurs. For example, with an 8 mm oscillating head held at a distance of 80 mm and an angle of 88° to the face of the substrate, an area 80 mm wide and 5 mm deep can be delaminated.

[0114] In one embodiment, the thickness of the rubber material to be peeled is between 5 mm and 10 mm thick.

[0115] In one embodiment, the speed at which the rubber material is peeled off is between 2 m / min and 4 m / min, such as between 2.5 m / min and 3.5 m / min, for example about 2.8 m / min.

[0116] As mentioned above, in the present invention, the composite product sheets (provided in step a) or obtained in step bi) are standardized in thickness. It has been found that by using a specific standardized thickness sheet for the composite product, in step c), the water strips the uncured rubber from the composite product, resulting in a mixture comprising uncured rubber and reinforcing material.

[0117] Beneficially, there is therefore a peeling effect on the rubber rather than a grinding effect.

[0118] The uncured rubber can then be easily removed from the reinforcing material.

[0119] It has been found that by using the process according to the invention, the uncured rubber separates from the reinforcing material in the form of granules and / or powder, and is therefore advantageously in a particulate form that can be easily removed and processed.

[0120] The water used in step c) may be at room temperature or it may be heated, in one embodiment the water used is heated, which has been found to improve the peeling process.

[0121] In one embodiment, the water may be preheated to a temperature of up to 90° C., preferably between 40° C. and 90° C., before being sprayed onto the sheet.

[0122] Those skilled in the art will appreciate that pressurizing water to high pressures results in an increase in the temperature of the water, but in the present invention, external heat is provided to the water to achieve a controlled temperature.

[0123] Heating of the water may be performed, for example, using a burner heater to heat the water before it is sprayed onto the sheet. Those skilled in the art will recognize that since the water does not reach the same temperature as the burner itself, the burner temperature may be set higher than the desired temperature of the water, for example, the burner temperature may be set at 150° C.

[0124] In a preferred embodiment, the water is preheated to a temperature of from 40° C. to 80° C. or from 50° C. to 70° C. before being sprayed onto the sheet.

[0125] In one embodiment, preheated water is used to heat the uncured rubber to a temperature of from 35°C to 50°C, preferably from 40°C to 50°C, for example from 40°C to 45°C.

[0126] In one preferred embodiment, the water is preheated to about 80° C., which may have the effect of heating the uncured rubber to a temperature of about 45° C. In another preferred embodiment, the water is preheated using a burner to about 60° C., which may have the effect of heating the uncured rubber to a temperature of about 40° C.

[0127] In one embodiment, the water is provided as cold water at a temperature of about 5° C. to 15° C., such as about 9° C., and the water is then heated by application of pressure, resulting in a substrate temperature in the range of, for example, 20° C. to 25° C. This can be particularly useful when the reinforcing material is a metal.

[0128] In another embodiment, the reinforcing material is fibre and the water is provided at a temperature in the range of 35° C. to 50° C., for example at about 39° C. Suitably the pressure may be from 275 bar to 340 bar, with 340 bar being the most preferred pressure, especially when using a substrate with a thickness of 5 mm. At 340 bar no damage to the fibres is observed apart from the dip coating being removed, at 275 bar the dip coating on the fibres is largely left intact.

[0129] In one embodiment, the fiber reinforced material reaches a temperature in the range of 30°C to 40°C, such as about 36°C.

[0130] The flow rate used for water may be, for example, 5 L / min to 80 L / min or more, such as 7 L / min to 60 L / min or more. In one embodiment, the flow rate is 5 L / min to 50 L / min, such as 7 L / min to 40 L / min. In one embodiment, the flow rate is 5 L / min to 30 L / min, such as 7 L / min to 15 L / min.

[0131] In one embodiment, especially when the reinforcing material is a fiber, the standardized sheet is constrained between two conveyors to minimize movement and ensure a good stripping effect. The conveyors may suitably be mesh conveyors. The upper conveyor may be an open wire mesh, for example with an open wire mesh of 10 to 20 mm, for example to limit the deflection of the water jet. The lower conveyor may be, for example, a solid belt or a steel slat conveyor.

[0132] Use of a lower conveyor that includes openings, such as holes or slats, can be beneficial in that this allows water and exfoliated uncured rubber material to pass through. In one embodiment, the lower conveyor includes a plurality of openings, e.g., a plurality of cut holes, which may have a maximum diameter of, for example, 5 mm to 20 mm, such as about 10 mm. The openings may, for example, make up 50% to 60% of the surface area of ​​the lower conveyor.

[0133] The lower conveyor may be connected to a housing positioned to collect the peeled, uncured rubber material.

[0134] <Rubber> During step c) (the "power washing" stage), the uncured rubber peels away from the reinforcing materials and is therefore separated from these. The uncured rubber is no longer bonded to the metal and / or fiber reinforcing materials and forms powders and / or granules that can be easily removed.

[0135] Thus, as a further step in the process, the uncured rubber may be removed from the mixture, eg, the rubber may be stripped.

[0136] The uncured rubber, for example in the form of rubber granules, may optionally be dried.

[0137] The water content associated with the water injection process may mean that a drying scheme capable of delivering, for example, 1 kwh / kg of rubber should be selected.

[0138] The uncured rubber can be dried using standard drying techniques. This may be, for example, by continuous drying or by a fluidized bed dryer. In one embodiment, rubber drying is carried out using air drying or radio frequency drying. One preferred drying method is by a rotary dryer supplied with hot air maintained at, for example, 70°C to 90°C, such as about 80°C.

[0139] Those skilled in the art will recognize that drying should be carried out under conditions that do not cure the rubber. The objective is to remove the water but leave the rubber in an uncured form so that it can be reused. In one embodiment, drying is carried out at a temperature below 90° C., for example, from 50° C. to 80° C.

[0140] The maximum temperature of the rubber crumb should not exceed 90° C. By using drying with a rotary dryer supplying hot air at about 80° C., it is possible, for example, to ensure that the maximum temperature of the crumb is 65° C.

[0141] In one preferred embodiment of the invention, the uncured rubber is transported across a vibrating conveyor and through an oven equipped with hot air plenums, preferably located above and below the conveyor.

[0142] The uncured rubber may optionally be subjected to rubber conditioning.

[0143] The uncured rubber, preferably in a dry form, may be packaged for storage and / or transportation.

[0144] In one embodiment, the dry rubber granules are fed into a hopper and baler. In a preferred embodiment, the baler is a vertical configuration fill and seal machine.

[0145] The rubber may be suitably packaged in a bag, such as a low melt EVA bag, for storage.

[0146] The dry rubber thus obtained is in an uncured (unvulcanized) form and can be accumulated and baled. The dry rubber thus obtained is ready for direct use in downstream compounding steps.

[0147] In one embodiment, the uncured rubber is then subsequently recompounded.

[0148] Because the rubber is still unvulcanized and metal and fiber free, the rubber may be used in its original application or compounded for an alternative application.

[0149] <Metal> During step c), the uncured rubber peels away from the metal and / or textile reinforcing materials and is therefore separated from these reinforcing materials.

[0150] Thus, as a further step in the process, the process may include separating the metal reinforcing material from the mixture, for example by use of a magnet.

[0151] Thus, a magnet, such as a drum magnet or an overband magnet, can be used to remove the metal from the body of separated material.

[0152] Once separated from the mixture, the metal reinforcing material may be packaged for storage and / or transportation.

[0153] In one embodiment, the metal reinforcing material is placed in a collection vessel.

[0154] <Textile> During step c), the uncured rubber peels away from the metal and / or textile reinforcing materials and is therefore separated from these reinforcing materials.

[0155] Thus, as a further step in the process, the process may include separating the fibres from the mixture, for example by use of a filter or screen, or by suction or flotation.

[0156] Thus, in one embodiment, the fibers can be removed from the body of separated material by the use of a sieve, such as a moving sieve. The fibers can be in the form of strips, or strands, or fibers. Thus, the fibers can be collected in a moving sieve that rotates and releases the fibers, for example, into a collection vessel.

[0157] In another embodiment, the fibers can be removed from the body of separated material by the use of flotation.

[0158] In yet another embodiment, the fibers can be removed from the body of separated material by drying with the rubber and then removing by suction.

[0159] In one embodiment, a vibrating pintle belt can be used to remove the fibers from the body of separated material. The lengths of fiber are collected on the top of the pintle, and the crumb falls to the base of the pintle and onto the belt, where it is vibrated off the belt. The fibers are collected as the belt returns to its downward trajectory.

[0160] The pintle belt can be made of any conventional belt substrate, such as rubber or PTFE coated fiberglass material. In one embodiment, the pintle is attached or molded into the belt substrate perpendicular to the plane of the belt. The pintle may be made of any substrate, such as rubber or metal. The pintle may be positioned on a portion or the entire surface of the belt substrate. The pintles may be spaced apart at any suitable distance, for example, 100 mm or less, or 50 mm or less, but preferably at a distance of 5 mm to 45 mm. The pintle belt may be used at an angle of 45° to 75°, for example about 60°, in one embodiment.

[0161] Once separated from the mixture, the fiber reinforcement material may be packaged for storage and / or transportation.

[0162] In one embodiment, the fiber reinforcement material is placed in a collection vessel. EXAMPLES

[0163] Example 1: Water jet pressure on standardized sheet samples A sample of a textile friction layer (uncured rubber + nylon textile fiber), a sample of a metallic friction material (uncured rubber + steel), and a sample of an uncured tire composite (uncured rubber + nylon textile fiber + steel) were provided.

[0164] Each was provided in sheet form or cut into sheets.

[0165] The sheet was then compressed by applying a weight as a force to a metal plate to obtain a standardized thickness. Examples tested included samples of the sheet ranging in thickness from 30 mm to 100 mm.

[0166] Each standardized sheet was then sprayed with pressurized water over both the top and bottom surfaces using a predefined nozzle and pressure configuration.

[0167] In some tests, the substrate was preheated prior to water injection. In some tests, the water was preheated prior to injection.

[0168] The details and results are given in the table below.

[0169] [Table 1]

[0170] If pressures above 500 bar are used, it will not be possible to cleanly separate the uncured rubber from the reinforcement without damaging the reinforcement, for example fibre collapse will occur, the uncured rubber will become contaminated with fibres or metal and the material will not prove to be in a form that can be reused.

[0171] In contrast, it was found that when pressures of 500 bar or less were used, the rubber could be cleanly removed from the reinforcement, forming granules which could be easily removed, leaving the reinforcement undamaged and reusable. Results were good for standardized sheet thicknesses ranging from 30 mm to 100 mm.

[0172] Thus, the benefit of the present invention is that it allows for the recovery of uncured rubber in a reusable form, and that the uncured rubber is of a clean quality such that it can be recomposed as virgin material.

[0173] It is advantageous from a "green" perspective that the requirement for virgin raw materials is reduced and the associated environmental impacts such as carbon emissions and natural resource consumption are reduced.

[0174] The process of the present invention also advantageously allows both the metal and fiber reinforcing materials to be separated and recovered in intact form, allowing these constituent materials to be reused.

[0175] <Example 2: Distance and angle of injection> A variety of metal and textile friction sheets standardized according to the present invention were provided and placed on a metal wire mesh conveyor, which was 88 cm long and made from 5 mm diameter wire in a linked geometric shape exhibiting 10 mm triangular openings.

[0176] The water jet lance was gripped by a fixed bracket allowing the nozzle to be moved relative to the substrate.The rubber was then peeled off from the standardized sheet of composite product using an internal oscillating water jet nozzle with a diameter of 8 mm.

[0177] The water injection unit used was a variable pressure and temperature unit with a maximum pressure of 500 bar and a maximum temperature of 95° C. The maximum water flow rate was 30 L / min.

[0178] The lance and an 8 mm water jet nozzle with internal oscillation were positioned at various distances and angles relative to the material.

[0179] Distances ranging from 15mm to 200mm were used to remove the uncured rubber. Results showed that the optimum distance from the substrate to ensure a wide range of uncured rubber was successfully removed was about 40mm to 100mm, particularly about 60mm to 80mm. In contrast, moving the lance further away from the substrate, for example to a distance of about 200mm, caused the retaining mesh conveyor to deflect the flow.

[0180] The results showed that a range of angles could be used successfully, with the results showing that angles between 62° and 90°, and especially between 70° and 88°, were useful in ensuring that uncured rubber was successfully removed from a large area.

[0181] <Example 3: Example of drying conditions for rubber> Two rubber samples were obtained, separated from the fibrous friction material according to the present invention. The rubber samples were dried (i) using an air circulating drying oven and (ii) in a rotary dryer. The temperature was measured using a junction K-type thermocouple.

[0182] Drying oven: A sample weighing 101.2 g was placed in the drying oven. The dryer set point was set at 80° C. After 1 hour 36 minutes the weight loss of the sample stabilized and the sample was found to weigh 67.4 g. The moisture content associated with the water injection was found to be 33.4%. The final temperature of the rubber was found to be 72.3° C.

[0183] Tumble dryer: A sample weighing 235.6 g was placed in the tumble dryer. The oven temperature was set at 80° C. The stable weight loss of the rubber after 16 minutes was found to be 67.1 g and the moisture content was found to be 28.48%. The final temperature of the rubber was found to be 65° C.

Claims

1. 1. A process for recovering constituent materials from a composite product, comprising: a) providing a composite product comprising a plurality of components, said components comprising uncured rubber and a reinforcing material selected from fiber and / or metal; b) providing one or more standardized sheets of a composite product, each having a maximum thickness of 125 mm or less; c) spraying pressurized water at a pressure of up to 500 bar onto one or more surfaces of the standardized sheet, thereby stripping the uncured rubber from the reinforcing material, resulting in a mixture of uncured rubber fibers and reinforcing material; The process includes:

2. 10. The process of claim 1, wherein the composite product provided in step a) comprises uncured rubber, a fiber reinforcement material, and a metal reinforcement material.

3. 3. The process of claim 1 or 2, wherein the composite product provided in step a) comprises a fiber reinforcement material selected from rayon, nylon, polyester, and aramid, and combinations thereof.

4. 3. The process of claim 1 or 2, wherein the composite product provided in step a) comprises a metal reinforcing material that is steel.

5. 3. The process of claim 1 or 2, wherein step b) comprises providing one or more standardized sheets of the composite product, each standardized sheet having a maximum thickness of 110 mm or less, such as 100 mm or less.

6. 3. The process according to claim 1 or 2, wherein in step b) the sheets are thickness standardized so that they all have the same maximum thickness within a tolerance of ±5 mm.

7. wherein the composite product provided in step a) is not in the form of a sheet, Step b) bi) cutting said composite product into the form of one or more cut sheets; and then b-ii) performing thickness normalization on each cut sheet such that each sheet has a thickness of 125 mm or less, such as 100 mm or less; 3. The process of claim 1 or 2, comprising:

8. the composite product provided in step a) is in the form of a sheet; 3. The process of claim 1 or 2, wherein step b) comprises: b-0) performing a thickness normalization such that each sheet has a thickness of 125 mm or less, such as 100 mm or less.

9. 8. The process of claim 7, wherein the sheet obtained in step bi) has a thickness of up to 500 mm, such as a thickness of 150 mm to 400 mm. Alternatively, the process of claim 8, wherein the sheet provided in step a) has a thickness of up to 500 mm, such as a thickness of 150 mm to 400 mm.

10. 3. The process of claim 1 or 2, wherein the thickness normalization step comprises applying pressure to each sheet, such as by using a calendar press, a belt press, or a hydraulic press.

11. 3. The process according to claim 1 or 2, wherein in step b) the sheet is subjected to a thickness standardization so that the sheet has a maximum thickness of 60 mm or less, such as from 3 mm to 40 mm.

12. 3. The process according to claim 1 or 2, wherein before step c), the sheet obtained from step b) is preheated to a temperature of from 40°C to 90°C.

13. 3. The process of claim 1 or 2, wherein in step c) the water is preheated to 40 to 90°C before being sprayed onto the sheet.

14. 3. The process of claim 1 or 2, wherein in step c) nozzles are positioned both above and below the sheet, thereby directing pressurized water onto both the upper and lower surfaces of the sheet.

15. 3. The process of claim 1 or 2, wherein in step c) pressurized water is directed over 75% or more of the surface area of ​​the sheet.

16. 3. The process of claim 1 or 2, wherein in step c) a vibrating nozzle is used to spray the pressurized water over the surface of the sheet.

17. 3. The process according to claim 1 or 2, wherein in step c) the water is used at a pressure of (a) from 130 bar to 500 bar, or (b) from 130 bar to 495 bar, or (c) from 150 bar to 450 bar, or (d) from 200 bar to 400 bar.

18. The process further comprises: d) separating the metal from the mixture, for example by using a magnet; and / or e) separating the fibers from the mixture, for example by using a filter or screen, or by suction or flotation; and / or f) Separating the uncured rubber from the mixture, e.g., the rubber may be removed.

3. The process of claim 1 or 2, comprising one or more, such as two or more, of:

19. 20. The process of claim 18, wherein the uncured rubber is separated, then dried, and optionally, then packaged for storage and / or transportation.

20. 20. The process of claim 19, wherein the uncured rubber is subsequently recompounded or reused.

21. 20. The process of claim 18, wherein the metal is subsequently reused.

22. 20. The process of claim 18, wherein the fibers are subsequently reused.