Patent Application
20220258401
The present disclosure generally relates to apparatus and methods for reworking of rubber, in particular non-vulcanised rubber and/or de-vulcanised rubber from a rubber component. The present disclosure further relates to a system and a method for recycling of the rubber.
In prior art systems used rubber components, such as end-of-life tires (ELTs) are shredded. Since the ELTs contain metallic and textile components in addition to rubber, the prior art processes produce an impure material (rubber+metallic+textile) as output. In particular, textile components (textile cords) cannot be divided from the rubber. This leads to the problem that the shredded used rubber components cannot be de-vulcanised, because the presence of those impurities inhibits the cracking of the cross-links, e.g. Sulphur links of the rubber. Furthermore, since the rubber is not de-vulcanised and contains impurities, the use of such recycled rubber components is very limited.
Systems for reworking of rubber, e.g. rubber production waste, according to the prior art, comprised of a first mixer or cracking mill which is used to soften the rubber. Afterwards the rubber is homogenised in a second mixer or mill station. Disadvantageously, those reworking systems imply a big consumption of energy and footprint, due to the need of several mill stations. Furthermore, those reworking systems can only rework non-vulcanised rubber.
EP 1 458 536 A1 relates to a process and apparatus for continuously producing an elastomeric composition. The process comprises the steps of: a) metering at least one elastomer, at least one filler and at least one minor ingredient; b) feeding said at least one elastomer, at least one filler and at least one minor ingredient into at least one extruder; c) mixing and dispersing said at least one filler and at least one minor ingredient into said at least one elastomer by means of said at least one extruder; d) obtaining a subdivided product from the resulting elastomeric composition discharged from said at least one extruder; e) accumulating an amount of said subdivided product, and f) stirring said accumulated amount of subdivided product.
EP 3 178 628 A1 relates to a method for producing a modified rubber mixture, in which an input rubber mixture from a masterbatch with a rubber component in an externally closed, pressure and gas-tight unit at a pressure of at least 63 bar and a temperature of at least 31° C. is mixed with supercritical CO 2 and subsequently extruded.
US 2005/006813 A1 relates to a system for kneading and extruding a material including a crusher for crushing the material into coarse particles, an extruder for conveying and extruding the material crushed by the crusher, a gear pump for receiving and discharging the material extruded from the extruder, and a kneading and extruding apparatus for kneading the material discharged from the gear pump and continuously extruding the kneaded material.
It is an object of the present invention to overcome the above mentioned problems of the related art. In particular, it is an object of the present invention to provide an apparatus and a method which provide high quality reusable rubber from rubber components. It is a further object of the present invention to provide an apparatus and a method with a small footprint and low energy consumption.
The above-mentioned objects are achieved with the features of the independent claims. Dependent claims define preferred embodiments of the invention.
In particular, according to the present invention, an apparatus for reworking of non-vulcanised rubber or de-vulcanised rubber from a rubber component, preferably a rubber tire, comprises a gear pump configured to receive and filter the rubber to produce filtered rubber, and a mixer-extruder configured to homogenize and extrude the filtered rubber to produce recycled rubber.
In accordance with an embodiment, the gear pump may be a stand alone gear pump.
In accordance with an embodiment the gear pump is provided before the extruder and preferably configured to receive cold rubber.
Preferably, the gear pump comprises at least one mesh or grid at its output which is configured to filter inhomogenities.
The the mixer-extruder may comprise a mixer.
The mixer may be configured to add to the rubber at least one element of the group consisting of: additives, fillers, polymers, plasticizers or activators.
Preferably, the mixer is also configured to add to the rubber at least one accelerator and at least one crosslinker to produce recycled rubber. Preferably, the accelerator is at least one of CBS and ZBEC. Preferably, the crosslinker is sulphur 95%.
The mixer-extruder preferably comprises an extruder head configured to extrude the recycled rubber.
Preferably, the extruder head is coupled to an output end of the of the mixer-extruder.
According to another aspect, the present invention provides a system for recycling of non-vulcanised rubber or de-vulcanised rubber from a rubber component, preferably a rubber tire. The system comprises an apparatus for removing rubber from the rubber component and an apparatus for reworking of non-vulcanised rubber or de-vulcanized rubber configured to produce recycled rubber, preferably using the removed rubber.
Preferably, the system further comprises an apparatus for de-vulcanisation of rubber, preferably removed from the rubber component.
According to another aspect, the present invention provides a method for reworking non-vulcanised rubber or de-vulcanised rubber from a rubber component, preferably a rubber tire, to produce and extrude recycled rubber. The method comprises the steps of filtering the rubber, homogenizing the filtered rubber to produce recycled rubber, and extruding the recycled rubber.
The foregoing steps of the method are preferably executed in the above-mentioned order, i.e. the step of filtering the rubber is preferably executed before the homogenizing step and the extruding step.
Preferably, the step of homogenizing the rubber comprises the step of adding to the rubber at least one element of the group consisting of: additives, fillers, polymers, plasticizers and activators.
Further preferably, the step of homogenizing the rubber comprises the step of adding to the rubber at least one accelerator and at least one crosslinker. The accelerator preferably is at least one of CBS or ZBEC. The crosslinker is preferably sulphur 95%.
According to another aspect, the present invention provides a method for recycling of non-vulcanised rubber or de-vulcanised rubber from a rubber component, preferably a rubber tire, or de-vulcanised rubber. The method comprises a method of removing rubber from a rubber component and a method for reworking the rubber to produce recycled rubber as mentioned above.
Preferably the method further comprises a method for de-vulcanisation of the rubber, preferably the rubber removed from a rubber component, to produce de-vulcanised rubber.
In general, the present invention aims at realizing an innovative process for recycling rubber, preferably used rubber or rubber production waste, e.g. in the tire industry. The process is a sequence of mechanical and/or chemical operations implemented by a compact dedicated recycling line to be implemented in two versions that apply to different phases of the rubber lifecycle as follows:
REWORK: the rework relates to tire production, i.e. to rework all scraps and non-compliant components and produce rubber 100% reusable for producing new rubber products.
RECYCLE: the recycle process relates to recovering rubber from end-of-life tires (ELT) or any used rubber components to produce sheeted rubber usable for molded applications, which includes pre-conditioning phases to clear rubber from textile cords.
The above mentioned rework may be a part of the overall recycle process.
The recycle process may be sub-divided into the following operations and related machines: a) Removing of rubber. This may be done by peeling or scrapping the rubber from rubber components, e.g. from ELTs, to produce rubber chips; b) De-vulcanisation of vulcanized rubber. The rubber chips may be fed into an autoclave and subsequently into a mixer to produce rubber strips; c) Reworking of the rubber strips. The rubber strips may be fed into a cutting unit and subsequently into a gear pump and a mixer-extruder to produce reworked rubber.
In other words, the above mentioned recycling is an innovative process for recycling of rubber production waste or post-consumer rubber components. This process may be made of three phases: 1. Peeling rubber chips from the rubber component: peeling is performed by a rotor with milling knives that rotate against the rubber component and grate the surface to produce rubber chips. 2. Cleaning and sanitization of the rubber chips. 3. Mixing rubber chips with additives to crack the cross links, e.g. Sulphur links.
The present invention allows to divide rubber completely from other materials of the tires. By combining a peeler (remover device) grates rubber chips from ELT and is driven by a THz sensor, that can measure through the rubber and any textile layers and steel cords. Thus, enabling the rotation and grating of the peeler to stop before the textile and/or steel cords are reached, e.g. at a residual depth of rubber below 300 microns.
The rotor may have a configuration where the milling knives are separate components that can easily be mounted and dismounted from a supporting hub. Since the knives are subjected to wear and need to be periodically replaced, this solution facilitates maintenance.
As described above, the knives may be stainless steel disks with many teeth that are clamped to the supporting hub by conical inserts. With this solution, only the disk/knives, made of high-performance steel, must be replaced when teeth are worn off.
The optimal pitch, as described above, between the disk/knives is also a parameter which is appropriately selected. The grooves between the disks are the channels where the rubber chips are dragged away of the formation spot. Their dimension determines the capacity to drag away the chips that are quite non-uniform in terms of dimension and physical properties being obtained from end-of-life rubber.
The higher the number of disks the higher the capacity of the machine to remove rubber per single rotation pass. Conversely, the higher the disks, the shorter the pitch among them, a factor that increases lateral friction with the ELT and consequent heating, with the risk of deteriorating the properties of the rubber chips. The final optimization of the present invention as described herein is a trade-off between those considerations.
The rotor may be commanded by an electric motor that maintains a constant rotational speed and supports the resisting torque generated by the friction with the ELT. The rotor may also be commanded by a positioning system that performs three main functions: a.) placing the rotor in the correct position with respect to the ELT and moving it back when peeling operations are finished; b.) keeping the position of the rotor during operations by supporting the forces generated at the contact between the knives and the ELT; and c.) advancing the rotor with respect to the ELT depending on the progress of the peeling operation and upon command of the THz sensor that measures the residual depth of the rubber (i.e. the distance of the knives from the underlying textile cords) and stops the process when the threshold distance is reached.
A configuration with two independent and overlying actuation systems for the X- and Y-axes may preferably be used.
The screw balls may be used as actuators only while tubular guides are introduced to support reaction forces and increase stiffness.
The components may include an electric motor that commands rotation of the peeling rotor, a stepper motor that commands positioning of the peeling rotor, pneumatic actuators for the drum, a machine cabinet and an operator panel.
System integration may include mechanical structures, supporting structure for the THz sensor and a metallic cage to protect the operator. Moreover, system integration may also include electrical wiring, control and command software, and PLC/HMI programming.
As described above, a de-vulcanisation process may follow the peeler and the autoclave for performing de-vulcanization of rubber and conditioning of the rubber chips before entering the gear pump (rework process).
According to the invention dc-vulcanizing post-consumer rubber is provided. This process may comprise two main phases: a. cleaning and sanitization of rubber to be de-vulcanised, e.g. post-consumer rubber chips and b. mixing rubber chips with additives to crack the cross links, e.g. Sulphur links of the rubber.
De-vulcanizing rubber may be provided by using a mechanical-chemical process that applies very high mechanical stress, preferably tangential stresses on the rubber to be de-vulcanised together with at least one chemical additive.
In view of the aforementioned autoclave, a steam unit to clean and sanitize the rubber chips produced by the peeler may be provided before the rubber is fed to the mixer.
In view of the aforementioned mixer, a machine with tangential rotors to maximize the strain on the rubber chips so that they are subjected to a strong thermo-mechanical action suitable to break the cross links, e.g. Sulphur links, and achieve de-vulcanization may be provided.
Rubber strips may be obtained by the mixer and fed into the rework line to be conditioned. The rework line may be made by a gear pump and a mixer-extruder.
A screw (scroll) may installed before the gear pump to introduce the rubber strips into the machine. The gear pump may be fed by cold rubber and may have the function of filtering rubber coming out from mixer.
The mixer-extruder may integrate a mixer and an extruder head. The mixer-extruder may integrate in a single machine following the functions: cracking, homogenizing, and extruding.
In other words, the present invention provides a sequence of mechanical operations implemented by a compact dedicated line that reworks all type of rubber scraps and non-compliant intermediate components from, for example, tire production and produces rubber that is 100% reusable in the main production process, i.e. for producing new rubber products such as rubber tires.
The reworking is provided to serve, for example, tire-manufacturing plants and the design solutions adopted are optimized to facilitate installation into the typical production contexts.
The main benefits comprise the complete internal recycling of all non-compliant components and the increase of the yield of the production plant thus improving eco-efficiency and reducing variable costs.
The rework apparatus may comprise two main machines, i.e. a gear pump and a mixer-extruder, complemented by auxiliary units (pusher, conveyors, batcher, stretching and cooling unit) to form the integrated line.
The rework apparatus may be operated close to the tire production machines in order to process the non-compliant components without stopping the main production line.
The rework apparatus may have a capacity of 2.5 to 5.0 t/h. The main technical functions of the rework apparatus may be as followings:
For the tire manufacturing process, the rework apparatus may generate performance gains as follows:
The rework apparatus features important improvements with respect to prior art, made by multiple mill stations, which may be:
With the present invention the footprint can be reduced by 60%, mainly through the replacement of the three mills of the baseline rework by the mix-extruder, the capacity of the gear pump has been quadrupled up to 5 t/h, and the power installed has been lowered from 1.097 kW to 370 kW, compared with prior art.
In general, the reworking apparatus 400 can be fed with de-vulcanised rubber, which has been de-vulcanised by the apparatus 300 for de-vulcanisation, or with rubber that has not been vulcanized before and thus not been de-vulcanised by the apparatus 300 for de-vulcanisation.
The above mentioned apparatus 200, 300, 400 of the system 1 are next described separately in more detail. However, the below description of the individual apparatus 200, 300, 400 apply to the apparatus 200, 300, 400 in the system 1 for recycling of non-vulcanised rubber or de-vulcanised rubber of a rubber component.
The methods described herein may also be combined in the same manner as the apparatus. That is, the methods relating to removing, de-vulcanisation, and reworking may be combined to one method, wherein the de-vulcanisation method is optional, because it is only needed for recycling of vulcanized rubber.
Removing Apparatus
As shown in
The sensor 210 comprises a transmitter 211 disposed on one side of the rubber component 8 and configured to emit the electromagnetic signal 20 towards the rubber component 8, and a receiver 212 disposed at another side of the rubber component 8 and configured to receive the electromagnetic signal 21 refracted at the rubber component 8.
Alternatively, the sensor 210 comprises a transmitter 211 disposed on one side of the rubber component 8 and configured to emit the electromagnetic signal 20 towards the rubber component 8, and a receiver (not shown) disposed at the same side as the transmitter 211 of the rubber component 8 and configured to receive the electromagnetic signal 21 reflected at the rubber component 8.
The terahertz frequency is between 0.3 and 30 THz, preferably between 0.3 and 10 THz, more preferably between 0.3 and 6 THz and most preferably between 0.3 and 3 THz.
The remover device 220 is configured to remove the rubber until a residual thickness of the outer rubber layer of 1 mm, preferably 600 μm, more preferably 300 μm.
The sensor 210 is configured to evaluate refraction or reflection peaks in the received electromagnetic signal by performing a time-domain analysis to determine the thickness of the outer rubber layer on top of the textile components. Also, the sensor 210 is configured to continuously determine the thickness of the outer rubber layer on top of the textile components during removing and to cause the remover device 220 to stop removing if the determined thickness of the outer rubber layer is below a predetermined threshold.
The predetermined threshold is 1 mm, preferably 600 μm, more preferably 300 μm.
Furthermore, the remover device 220 comprises a rotor 221 having at least one blade 222 and one support hub 223. The at least one blade 222 is detachably mounted on the support hub 223. The least one blade 222 may be a stainless steel disk with a plurality of cutting teeth along an outer circumferential surface thereof.
The at least one stainless steel disk is configured to be removably clamped onto the support hub 223, preferably by conical inserts.
The at least one blade is provided in plurality of two, three, four, five or more. The distance between the blades is between 21 and 2 mm, preferably between 18 and 4 mm, more preferably between 10 and 4 mm, and most preferably about 6 mm. The number of blades is between 2 to 25, preferably 5 to 20, more preferably 5-15, even more preferably 5-10 and most preferably 10.
The apparatus 200 of the present invention preferably further comprises a positioning system 230 configured to position the rotor 221 with respect to the outer circumferential surface of the rubber component, based on the determined thickness of the outer rubber layer on top of the textile components.
In general, a characteristic of the waves in the THz frequency band is their interaction with the structure and composition of materials. Using this characteristic, it is then possible to obtain information about the internal structure of a sheet of material by analyzing the behavior of the electromagnetic beam when it crosses that sheet.
According to certain embodiments of the present invention it is preferred to precisely measure the overall thickness and the relative position of the internal textile cords 9 within the rubber component 8.
In
The measurement system (sensor 210) is based on the properties of electromagnetic waves that, when passing through a sheet of material, may be partially refracted (a variation in the reflection index is detected).
For example, a transmitter antenna sends a sequence of electromagnetic pulses that are focused as a beam on the surface of the sample to be measured through a set of lenses.
Considering the multilayer structure of rubberized fabric as illustrated in
Due to the various refractions, a receiver antenna captures pulses having covered different distances. Through a special time-domain analysis of the peaks of the signals, this information is used to estimate the thickness of materials.
The relationship between time (t), the thickness of the sample to be measured (D) and the reflection index (n) is expressed by the following formula, where v and c represent the speeds of the electromagnetic wave in the material and vacuum respectively:
The method comprises the steps of S210 transmitting an electromagnetic signal with a terahertz frequency onto the rubber component, S220 receiving the electromagnetic signal refracted or reflected at the rubber component, S230 determining the thickness of the outer rubber layer on top of the textile components based on the received electromagnetic signal, and S240 removing the rubber from the rubber component based on the determined thickness of the outer rubber layer on top of the textile components.
De-Vulcanisation Apparatus
According to another aspect, the present invention provides an apparatus 300 for de-vulcanisation of rubber from a rubber component 8. The rubber component 8 can be e.g. used rubber tires and/or rubber production waste. As schematically shown in
According to this embodiment the cleaning device is an autoclave. The cleaning device 310 is configured to clean and/or sanitize the rubber by applying heat and/or pressure to the rubber. The heat can be in a temperature range between 80 and 180 degree Celsius. Preferably the heat is in a range of 100 to 120 degree Celsius.
The pressure can be in a range between atmospheric pressure and 5.0 bar. Preferably the pressure is in a range between atmospheric pressure and 2.7 bar.
The at least one rotor 321 of the mixing device 320 has at least one blade which is configured to apply mechanical stress to the cleaned and/or sanitized rubber to de-vulcanise the cleaned and/or sanitized rubber. The blade is configured to apply the mechanical stress to the cleaned and/or sanitized rubber in a substantially tangential direction. The at least one rotor 321 has four blades. Preferably, two of the four blades are configured to apply the mechanical stress to the rubber, while the two other blades of the rotor 321 are smaller and configured to support mixing of materials/substances.
Beyond that, the mixing device 320 is further configured to add at least one chemical additive to the cleaned and/or sanitized rubber which aids breaking the cross-links of the cleaned and/or sanitized rubber. Preferably, the at least one chemical additive is a de-vulcanisation agent. The de-vulcanisation agent represents between 1% and 15% of the weight of the cleaned and/or sanitized rubber and is suitable to aid breaking cross-links of the cleaned and/or sanitized rubber. Preferably the de-vulcanisation agent represents 5% of the weight of the cleaned and/or sanitized rubber. Preferably, the two smaller blades of the rotor 321 enable a homogeneous mixing of the chemical additive and the rubber.
Reworking Apparatus
The gear pump 410 comprises at least one mesh or grid at its output which is configured to filter inhomogenities, e.g. scorches, dirt, impurities, grains etc. The mixer-extruder 420 comprises a mixer 421. The mixer 421 is configured to add to the rubber at least one element of the group consisting of: additives, fillers, polymers, plasticizers or activators. Preferably, the mixer 421 is also configured to add to the rubber at least one accelerator and at least one crosslinker to produce recycled rubber. Preferably, the accelerator is at least one of CBS and ZBEC. Preferably, the crosslinker is sulphur 95%.
The mixer-extruder 420 preferably comprises an extruder head 422 configured to extrude the recycled rubber. The extruder head 422 is coupled to the output end of the mixer-extruder 420. The extruder head 422 may also be coupled directly to the mixer-extruder 420, such that no means for transportation, e.g. conveyors, or other output means, e.g. sheeting mills, are necessary.
The step of homogenizing the rubber comprises the step of adding to the rubber at least one element of the group consisting of: additives, fillers, polymers, plasticizers and activators. Further, the step of homogenizing the rubber comprises the step of adding to the rubber at least one accelerator and at least one crosslinker. The accelerator preferably is at least one of CBS or ZBEC. The crosslinker is preferably sulphur 95%.
The system according to the present invention enables recycling of rubber, e.g. of rubber from used rubber components or rubber production waste. The recycled rubber is of high quality and has similar material properties as rubber produced from natural rubber.
This is achieved due to the process of removing the rubber with the aid of the apparatus for removing rubber, according to the present invention. In particular, only the rubber that covers the textile components of the rubber components is removed to be recycled. Therefore, the present application detects the position of the textile components via electromagnetic signals and stops the remover device, before the textile components are touched. Therefore, the removed material does not include textile or other non-rubber components, thereby avoiding inhomogeneities. With the apparatus for de-vulcanisation of rubber, according to the present invention, cleaned and sanitized rubber is produced as an intermediate product. This cleaned and sanitized rubber is de-vulcanised by the apparatus as of the present invention such that rubber which can be reprocessed is produced. Advantageously, this rubber does not contain non-rubber material, e.g. textile components.
The apparatus for reworking non-vulcanised rubber or de-vulcanized rubber enables to directly extrude recycled rubber, without the need of other extraction means. The recycled rubber is of high quality enabling a use in various contexts and fields.
The aforementioned features which may have been described solely with respect to the respective apparatus 200, 300, 400 apply to the respective methods as well. Their description in relation to the respective methods has simply be omitted to avoid any unnecessary repetitions.
As the present invention may be embodied in several forms without departing from the scope or essential characteristics thereof, it should be understood that the above-described embodiments are not limited by any of the details of the foregoing descriptions, unless otherwise specified, but rather should be construed broadly within the scope as defined in the appended claims, and therefore all changes and modifications that fall within the present invention are therefore intended to be embraced by the appended claims.
Furthermore, in the claims the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single unit may fulfil the functions of several features recited in the claims. The terms “essentially”, “about”, “approximately” and the like in connection with an attribute or a value particularly also define exactly the attribute or exactly the value, respectively. Any reference signs in the claims should not be construed as limiting the scope.
The present invention also relates to the following items:
| Number | Date | Country | Kind |
|---|---|---|---|
| 19200215.2 | Sep 2019 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/076879 | 9/25/2020 | WO |
