WO2010073275A1 - Process and plant for producing tyres - Google Patents
Process and plant for producing tyres Download PDFInfo
- Publication number
- WO2010073275A1 WO2010073275A1 PCT/IT2008/000794 IT2008000794W WO2010073275A1 WO 2010073275 A1 WO2010073275 A1 WO 2010073275A1 IT 2008000794 W IT2008000794 W IT 2008000794W WO 2010073275 A1 WO2010073275 A1 WO 2010073275A1
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- WIPO (PCT)
- Prior art keywords
- elastomeric compound
- mixing device
- plant
- producing
- shaft continuous
- Prior art date
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D30/00—Producing pneumatic or solid tyres or parts thereof
- B29D30/005—General arrangement or lay-out of plants for the processing of tyres or parts thereof
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B7/00—Mixing; Kneading
- B29B7/002—Methods
- B29B7/005—Methods for mixing in batches
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B7/00—Mixing; Kneading
- B29B7/002—Methods
- B29B7/007—Methods for continuous mixing
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B7/00—Mixing; Kneading
- B29B7/02—Mixing; Kneading non-continuous, with mechanical mixing or kneading devices, i.e. batch type
- B29B7/06—Mixing; Kneading non-continuous, with mechanical mixing or kneading devices, i.e. batch type with movable mixing or kneading devices
- B29B7/10—Mixing; Kneading non-continuous, with mechanical mixing or kneading devices, i.e. batch type with movable mixing or kneading devices rotary
- B29B7/18—Mixing; Kneading non-continuous, with mechanical mixing or kneading devices, i.e. batch type with movable mixing or kneading devices rotary with more than one shaft
- B29B7/183—Mixing; Kneading non-continuous, with mechanical mixing or kneading devices, i.e. batch type with movable mixing or kneading devices rotary with more than one shaft having a casing closely surrounding the rotors, e.g. of Banbury type
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B7/00—Mixing; Kneading
- B29B7/02—Mixing; Kneading non-continuous, with mechanical mixing or kneading devices, i.e. batch type
- B29B7/22—Component parts, details or accessories; Auxiliary operations
- B29B7/28—Component parts, details or accessories; Auxiliary operations for measuring, controlling or regulating, e.g. viscosity control
- B29B7/286—Component parts, details or accessories; Auxiliary operations for measuring, controlling or regulating, e.g. viscosity control measuring properties of the mixture, e.g. temperature, density
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B7/00—Mixing; Kneading
- B29B7/30—Mixing; Kneading continuous, with mechanical mixing or kneading devices
- B29B7/34—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices
- B29B7/38—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary
- B29B7/46—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with more than one shaft
- B29B7/48—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with more than one shaft with intermeshing devices, e.g. screws
- B29B7/485—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with more than one shaft with intermeshing devices, e.g. screws with three or more shafts provided with screws
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B7/00—Mixing; Kneading
- B29B7/74—Mixing; Kneading using other mixers or combinations of mixers, e.g. of dissimilar mixers ; Plant
- B29B7/7461—Combinations of dissimilar mixers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B7/00—Mixing; Kneading
- B29B7/80—Component parts, details or accessories; Auxiliary operations
- B29B7/88—Adding charges, i.e. additives
- B29B7/90—Fillers or reinforcements, e.g. fibres
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/285—Feeding the extrusion material to the extruder
- B29C48/286—Raw material dosing
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/285—Feeding the extrusion material to the extruder
- B29C48/287—Raw material pre-treatment while feeding
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
- B29C48/375—Plasticisers, homogenisers or feeders comprising two or more stages
- B29C48/385—Plasticisers, homogenisers or feeders comprising two or more stages using two or more serially arranged screws in separate barrels
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
- B29C48/395—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders
- B29C48/40—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders using two or more parallel screws or at least two parallel non-intermeshing screws, e.g. twin screw extruders
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
- B29C48/395—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders
- B29C48/40—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders using two or more parallel screws or at least two parallel non-intermeshing screws, e.g. twin screw extruders
- B29C48/405—Intermeshing co-rotating screws
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
- B29C48/50—Details of extruders
- B29C48/505—Screws
- B29C48/535—Screws with thread pitch varying along the longitudinal axis
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
- B29C48/50—Details of extruders
- B29C48/68—Barrels or cylinders
- B29C48/683—Barrels or cylinders for more than two screws
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C2948/00—Indexing scheme relating to extrusion moulding
- B29C2948/92—Measuring, controlling or regulating
- B29C2948/92504—Controlled parameter
- B29C2948/9258—Velocity
- B29C2948/926—Flow or feed rate
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C2948/00—Indexing scheme relating to extrusion moulding
- B29C2948/92—Measuring, controlling or regulating
- B29C2948/92504—Controlled parameter
- B29C2948/92704—Temperature
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C2948/00—Indexing scheme relating to extrusion moulding
- B29C2948/92—Measuring, controlling or regulating
- B29C2948/92819—Location or phase of control
- B29C2948/92857—Extrusion unit
- B29C2948/92866—Inlet shaft or slot, e.g. passive hopper; Injector, e.g. injector nozzle on barrel
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
- B29C48/07—Flat, e.g. panels
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
- B29C48/395—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders
- B29C48/40—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders using two or more parallel screws or at least two parallel non-intermeshing screws, e.g. twin screw extruders
- B29C48/425—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders using two or more parallel screws or at least two parallel non-intermeshing screws, e.g. twin screw extruders using three or more screws
- B29C48/43—Ring extruders
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/92—Measuring, controlling or regulating
Definitions
- the present invention relates to a process and a plant for producing tyres.
- the present invention also relates to a process and a plant for producing an elastomeric compound.
- the present invention relates to a process and plant for producing tyres in which at least one elastomeric compound used in the manufacturing of one or more tyre structural elements is produced by at least one mixing step carried out in at least one batch mixing device, and at least one mixing step carried out in a multi-shaft continuous mixing device.
- elastomeric compounds used in the manufacturing of tyres is performed batchwise by means of batch mixing devices, e.g. internal mixers such as, for example, Banbury ® mixers, having two counter-rotating rotors which exert an intensive mixing action to masticate the elastomeric polymer(s) and to incorporate and thoroughly disperse therein the other components usually present in the elastomeric compounds such as, for example, reinforcing fillers, lubricating aids, curatives and other additives.
- batch mixing devices e.g. internal mixers such as, for example, Banbury ® mixers, having two counter-rotating rotors which exert an intensive mixing action to masticate the elastomeric polymer(s) and to incorporate and thoroughly disperse therein the other components usually present in the elastomeric compounds such as, for example, reinforcing fillers, lubricating aids, curatives and other additives.
- the production of elastomeric compounds using batch mixing devices shows many drawbacks, particularly a poor heat dissipation and thus a scarce temperature control, mainly due to an unfavorable ratio between material volume and mixer surface area.
- the various components, and particularly the reinforcing fillers are usually incorporated into the elastomeric polymer(s) in batches distributed in a plurality of mixing operations separated by cooling and storage steps.
- the temperature sensitive components, such as crosslinking agents and accelerators are added only during the final mixing step, after the cooling of the elastomeric compounds below a predetermined temperature (usually below 110°C) to avoid premature crosslinking ("scorching" phenomena) .
- United States Patent US 4,897,236 discloses a process and an apparatus for continuously producing a rubber mixture, wherein the ingredients of the mixture are fed, masticated and homogenized in a twin-screw extruder.
- the resulting mixture is divided into a first and a second portion.
- the first portion is discharged, while the second portion is recycled for further homogenization and for mixing with fresh batches of the ingredients being fed to the extruder.
- the recycled portion is circulated to and returned from a cooled, annular chamber exterior to the extruder chamber, said annular chamber having outflow and inflow passages communicating with the interior of the extruder.
- United States Patent US 5,626,420 discloses a continuous mixing process and apparatus, wherein base elastomer(s) and other components are continuously dosed and introduced into a mixing chamber formed of a stator and a rotor rotating therein, preferably a single screw extruder.
- the introduced components advance within the mixing chamber along zones of propulsion and mixing.
- the filling rate of the mixing chamber in at least certain mixing zones is lower than 1.
- force feeding means are used, such as volumetric pumps (e.g. gear pumps).
- United States Patent Application US 2004/0094862 discloses a multi-shaft extruder with at least two shafts for compounding and/or molding an elastomer staggered with filler, in particular rubber, with at least softener and/or additives.
- the extruder comprises the following in succession in the direction of product transport: a feed zone, into which the elastomer and softener and/or additives are metered; a mastication/plasticization zone with at least one kneading element, into which the elastomer with the softener and/or additives is transferred to a flowable, cohesive mixture; a dispersing zone with at least one additional kneading element, in which the filler in the elastomer is comminuted and distributed; and the kneading elements having a comb and the extruder having a casing inner wall, and wherein a gap with a gap width Z of about 1/100 to about 1/10 of the kneading element diameter D is present between the comb of the kneading elements and the casing inner wall of the extruder.
- the multi-shaft extruder is a ring extruder.
- PCT Patent Application no. WO 03/009989 discloses a process and an apparatus for the continuous production of elastomeric compositions by means of at least one extruder, wherein the minor ingredients are used in the form of subdivided products.
- the products include at least one of the minor ingredients dispersed in a thermoplastic binding agent and are conveyed to a dosing device by means of a pneumatic conveying line, to be accurately metered and continuously fed into the extruder.
- the quality of the elastomeric compounds for tyres prepared by using batch mixing devices may be unsatisfactory: in particular, variations in the mechanical properties between different batches may be obtained, and dispersion of the reinforcing fillers may be, in some cases, poor.
- the number of mixing steps is increased.
- increasing the number of mixing steps in batch mixing device may cause a lot of drawbacks such as, for example, damages to the elastomeric polymer(s), worsening of the mechanical properties of the elastomeric compounds, premature crosslinking ("scorching" phenomena) of the elastomeric compounds.
- a high quality elastomeric compound can be obtained in a compounding plant of reduced complexity by producing the elastomeric compound with at least one mixing step carried out in at least one batch mixing device and at least one mixing step carried out in at least one continuous mixing device.
- the obtained elastomeric compound shows a significantly improved dispersion of the reinforcing filler(s), together with improved mechanical properties (both static and dynamic). A significant repeatability of the results obtained in terms of mechanical properties of the obtained elastomeric compounds has also been verified.
- batch mixing devices and continuous mixing devices are very different machines in terms of maximum throughput. While a batch mixing device is able to produce (with a number of batches) elastomeric compounds at a throughput of not less than 1000-2000 kg/hour, and preferably more, common continuous mixers such as twin screw extruders can hardly reach such throughputs for the production of elastomeric compounds. Differently from thermoplastic compounds, elastomeric compounds do not have a melting point, are thermally sensitive and prone to degradation, due to scorching phenomena and/or the occurrence of thermal reactions, when high screw rotation speed, and/or high shear rate, and/or high energy is used in order to improve the throughput.
- a twin screw extruder having a screw diameter of 40 mm can reach typical throughputs of less than 40-50 kg/hour for viscous elastomeric compounds, i.e. at least 50 times less than typical throughputs obtainable by batch mixing devices.
- the increasing of the size of a twin screw extruder does not lead to significant improvements in terms of obtained throughput: for example, it has been found that increasing the screw diameter of a twin screw extruder to about 90 mm leads to a throughput around 200-250 kg/hour for viscous elastomeric compounds, i.e.
- the high number of shafts allows increasing the throughput of the continuous mixing device to a value comparable with that of a batch mixing device without the need of increasing the screw rotation speed, and/or the shear rate, and/or the screw diameter to values which could lead to scorching of the compound. Furthermore, a superior quality of a compound prepared at the batch mixing device and subsequently processed at the multi-shaft continuous mixing device has been verified. Moreover, the desired throughputs can be obtained even with machines having low screw diameter, so that the length of the multi-shaft continuous mixing device can be also kept sufficiently low, thanks to the processing performed by the high number of parallel mixing screws.
- a compounding plant comprising at least one batch mixing device and at least one multi-shaft continuous mixing device does not need complex feeding systems for the feeding of the continuous mixing device, so that the overall size of the compounding plant can be advantageously contained. This is a great advantage when the compounding plant is part of a full tyre production plant, where many devices and areas are provided further to the devices related to compounding, such as devices adapted for preparing semifinished products, green tyre manufacturing machines, vulcanization presses, tyre quality control areas, etc..
- batch mixing device means a mixing device into which the components of the elastomeric compound are periodically fed in predefined amounts (batches) and mixed for a predetermined time so as to obtain the elastomeric compound. At the end of the mixing step, the obtained elastomeric compound is completely discharged from the mixing device.
- continuous mixing device means a mixing device into which the material to be processed to obtain an elastomeric compound is continuously fed (apart from possible stopping of the mixing device due to maintenance, or change of elastomeric compound recipe) and from which the elastomeric compound is discharged in a continuous stream, in contrast to the periodic charge/discharge of a batch mixing device.
- the present invention relates to a process for manufacturing a tyre, comprising: providing at least one crosslinkable elastomeric compound;
- a mixing apparatus including at least one batch mixing device; mixing and dispersing, in said mixing apparatus, said at least one reinforcing filler into said at least one elastomeric polymer, so as to obtain a first elastomeric compound;
- the present invention relates to a plant for manufacturing tyres, comprising: a compounding plant being adapted to produce at least one crosslinkable elastomeric compound; at least one manufacturing machine adapted for preparing a green tyre using a plurality of structural elements; at least one device adapted for preparing at least one structural element of said plurality of structural elements, wherein said at least one structural element comprises said at least one crosslinkable elastomeric compound; - at least one vulcanization press adapted to moulding and crosslinking said green tyre to obtain a finished tyre; wherein the compounding plant comprises: a mixing apparatus including at least one batch mixing device, said mixing apparatus being adapted to produce a first elastomeric compound; at least one multi-shaft continuous mixing device, said multi-shaft continuous mixing device comprising at least six rotating screws, said multi-shaft continuous mixing device being adapted to receive said first elastomeric compound and to produce a second elastomeric compound.
- the present invention relates to a process for producing an elastomeric compound, comprising: feeding at least one elastomeric polymer and at least one reinforcing filler to a mixing apparatus including at least one batch mixing device; mixing and dispersing, in said mixing apparatus, said at least one reinforcing filler into said at least one elastomeric polymer, so as to obtain a first elastomeric compound; discharging said first elastomeric compound from said mixing apparatus; feeding said first elastomeric compound to at least one multi-shaft continuous mixing device, said multi-shaft continuous mixing device comprising at least six rotating screws; mixing said first elastomeric compound into said at least one multi-shaft continuous mixing device, so as to obtain a second elastomeric compound.
- the present invention relates to a plant for producing an elastomeric compound, comprising: at least one mixing apparatus including at least one batch mixing device, said mixing apparatus being adapted to produce a first elastomeric compound; at least one multi-shaft continuous mixing device, said multi-shaft continuous mixing device comprising at least six rotating screws, said multi-shaft continuous mixing device being adapted to receive said first elastomeric compound and to produce a second elastomeric compound.
- the second elastomeric compound discharged from the multi-shaft continuous mixing device shows a significantly improved dispersion of said at least one reinforcing filler with respect to said first elastomeric compound, together with equivalent or even superior mechanical properties (both static and dynamic).
- the present invention in at least one of the abovementioned aspects, may show one or more of the preferred characteristics hereinafter disclosed.
- said process for producing the elastomeric compound may be carried out continuously or discontinuously.
- the first elastomeric compound is directly fed to said at least one multi-shaft continuous mixing device without being stored.
- said first elastomeric compound is fed to said at least one multi-shaft continuous mixing device after having being stored.
- said batch mixing device is selected from internal mixers, open mixers. Internal mixers are particularly preferred.
- said batch mixing device comprises a pair of rotors which operate tangentially relative to each other or are inter-penetrating.
- said batch mixing device comprises a mixing chamber internally housing a pair of rotors turning in opposite directions, so as to mix up the components introduced into the mixing chamber from the top thereof.
- said batch mixing device is usually provided with a pneumatic or hydraulic cylinder located in the upper part of the mixing chamber and a piston movable upwards to open the mixing chamber, thereby allowing the introduction of the components via special loading hoppers, and downwards so as to exert a pressure on the material processed by the rotors and located above them.
- a hydraulic system located on the bottom of the mixing chamber allows discharging of the elastomeric compound at the end of the mixing cycle by opening a suitable outlet.
- Internal mixers which may be advantageously used according to the present invention are those known under the tradename of Banbury ® or Intermix ® , depending on whether the rotors operate tangentially relative to each other or are interpenetrating. Banbury ® mixer is particularly preferred.
- open mixers which may be advantageously used according to the present invention are: open mill mixer, Z-blade mixer. Open mill mixer is particularly preferred.
- the mixing in said at least one batch mixing device may be carried out at a rotor speed of about 20 rpm to about 60 rpm, preferably of about 30 rpm to about 50 rpm.
- the mixing in said at least one batch mixing device may be carried out using a fill factor of the mixing chamber (the fill factor is the portion of the total free volume of the mixing chamber occupied by the material to be mixed) not higher than about 80%, preferably of about 55% to about 70%. If a too high fill factor is selected, lack of free volume prevents material movement and cross- blending, so that adequate mixing becomes problematic. Likewise, if only a very small fill factor is selected, it is difficult to ensure adequate mixing, with high shearing forces, and adequate homogenisation of the material in the mixing chamber.
- said at least one multi-shaft continuous mixing device comprises at least six co-rotating screws.
- the screws are preferably disposed so as to form a ring.
- said at least one multi-shaft continuous mixing device comprises at least twelve rotating screws, even more preferably co-rotating screws.
- Said rotating screws may comprise high-shear mixing elements such as kneaders or screw flights with low flight depth.
- the screw shafts are preferably parallel.
- the screws are at least partially intermeshed. More preferably, the screws are substantially fully intermeshed. Even more preferably, the screws are self-wipening.
- Preferred screw diameters range from at least 30 mm, more preferably from at least 60 mm.
- said multi-shaft continuous mixing extruder is a ring extruder comprising:
- the ring extruder comprises gas outlet openings provided in the outer housing, to allow removal of volatile material. Vacuum can be advantageously applied to said gas outlet openings, to further facilitate extraction of volatile material.
- the mixing in said at least one multi-shaft continuous mixing device may be carried out at a screw rotation speed of about 10 rpm to about 600 rpm, preferably of about 40 rpm to about 400 rpm.
- said screw rotation speed allows to obtain a very good dispersion of the ingredients, in particular of the reinforcing fillers, in the second elastomeric compound, as well as to avoid premature crosslinking ("scorching" phenomena) of the second elastomeric compound which may occur if a too high screw rotation speed is used.
- the second elastomeric compound can be discharged from said multi- shaft continuous mixing device at an average throughput of at least 500 kg/h, preferably of at least 800 kg/h.
- a compounding plant comprising a mixing apparatus including at least one batch mixing device in combination with one or two multi-shaft continuous mixing devices may reach an overall throughput compatible with a tyre production at industrial scale.
- the first elastomeric compound is cooled before feeding it to said at least one multi-shaft continuous mixing device.
- said first elastomeric compound may be cooled to a temperature from about 15°C to about 40 0 C, more preferably from about 20 0 C to about 25°C.
- At least one conveying extruder may be included in the compounding plant.
- the first elastomeric compound is fed to said at least one conveying extruder before being fed to said at least one multi-shaft continuous mixing device.
- said at least one conveying extruder comprises: a housing, said housing including at least one feed opening and a discharge opening; at least one conveying element rotatably mounted in said housing.
- conveying element means an element which does not substantially exert a mixing action but merely exerts a conveying of the elastomeric compound through the extruder length.
- Typical conveying elements may be selected, for example, from elements that mainly promote axial movement of the material such as helical screws.
- the conveying in said at least one conveying extruder may be exemplarily carried out at a conveying element speed from about 10 rpm to about 60 rpm, preferably from about 20 rpm to about 35 rpm.
- the feeding to said at least one conveying extruder may allow to control the feeding rate of the first elastomeric compound to the multi-shaft continuous mixing device.
- Said at least one conveying extruder may be a single helical screw extruders, or a dump extruder having two counter-rotating helical screws.
- said mixing apparatus includes at least one internal mixer and at least one open mixer, said open mixer being preferably placed downstream of said at least one internal mixer.
- the second elastomeric compound discharged from the at least one multi-shaft continuous mixing device can be fed to at least one further batch mixing device.
- Said at least one further batch mixing device may be selected from those above disclosed.
- said at least one multi-shaft continuous mixing device may be placed upstream of a device for preparing at least one structural element of a green tyre by using said second elastomeric compound discharged by the multi-shaft continuous mixing device, or by using a further compound obtained by a further mixing step performed on the second elastomeric compound.
- the device for preparing the green tyre structural element may be selected from those commonly known in the art such as, for example, calendering devices and/or extruder devices.
- said at least one multi-shaft continuous mixing device may be directly equipped with a roller die or with an extrusion die. Especially in the latter case, a green tyre structural element can be directly obtained at the output of said at least one multi-shaft continuous mixing device.
- Said green tyre structural element may be, for example, one of the different elastomeric structural elements of a tyre such as, for example: bead filler, sidewall, tread band, liner, underliner, antiabrasive layer. According to processes known in the art, said structural elements are subsequently assembled using a suitable manufacturing apparatus to give a finished tire.
- Another structural element obtainable by using said second elastomeric compound discharged by the multi-shaft continuous mixing device, or by using a further compound obtained by a further mixing step performed on the second elastomeric compound is a continuous elongated strip-like element.
- the continuous strip-like element can be laid down on a support (e.g. a forming drum) in a plurality of windings, so as to form a plurality of consecutive coils disposed in side by side and/or superposed relationship with each other.
- equivalents of many structural elements of a tyre typically obtained by semi-finished products, can be formed by the spiral windings.
- equivalents of a bead filler, a sidewall, a tread band, a liner, an underliner, an antiabrasive layer can be obtained by spiral winding of a continuous strip-like element.
- Said continuous strip-like element may have a flattened cross-sectional shape such as, for example, rectangular, elliptic, lenticular, or tapered shape.
- Cross-section dimensions of said continuous strip-like element may be considerably lower than the cross-section dimensions of the equivalent structural element to be obtained by spiral winding.
- Said continuous strip-like element can be obtained directly at the output of the multi- shaft continuous mixing device, through a suitable extrusion die.
- all the ingredients of the crosslinkable elastomeric compound are fed to said at least one mixing apparatus.
- vulcanizing agents such as, for example, sulfur, or molecules containing sulfur (sulfur donors), or mixtures thereof
- activators such as, for example, zinc compounds, and in particular ZnO, ZnCO 3 , zinc salts of saturated or unsaturated fatty acids containing from 8 to 18 carbon atoms, such as, for example, zinc stearate, which are preferably formed in situ in the elastomeric compound from ZnO and fatty acid, and also BiO, PbO, Pb 3 O 4 , PbO 2 , or mixtures thereof
- accelerators such as, for example, dithiocarbamates, guanidine, thiourea, thiazoles, sulphenamides, thiurams, amines, xanthates, or mixtures thereof
- the mixing may be preferably carried out in at least two different steps, the first step being a non-productive step wherein all the components except those able to promote the crosslinking (for example, sulfur and accelerators) are fed to said batch mixing device, the second step being a productive step wherein the elastomeric compound obtained from said first step as well as the components able to promote crosslinking are fed to said batch mixing device.
- the so obtained elastomeric compound i.e. the above mentioned first elastomeric compound
- all the components of the elastomeric compound, except from the components able to promote crosslinking are fed to a batch mixing device, e.g. an internal mixer such as a Banbury ® mixer, to obtain a first elastomeric compound which is subsequently fed to a multi-shaft continuous mixing device, so as to obtain a second elastomeric compound.
- a batch mixing device e.g. an internal mixer such as a Banbury ® mixer
- the so obtained second elastomeric compound, as well as the components able to promote crosslinking are subsequently fed to a further batch mixing device, e.g. an internal mixer such as a Banbury ® mixer, which is placed downstream of said multi-shaft continuous mixing device.
- all the components of the elastomeric compound, except from the components able to promote crosslinking are fed to a batch mixing device, e.g. an internal mixer such as a Banbury ® mixer, to obtain a first elastomeric compound.
- a batch mixing device e.g. an internal mixer such as a Banbury ® mixer.
- the so obtained first elastomeric compound, as well as the components able to promote crosslinking are subsequently fed to a multi-shaft continuous mixing device, so as to obtain a second elastomeric compound.
- an open mixer When an open mixer is used as a batch mixing device, preferably, all the components of the elastomeric compound are fed to said open mixer so as to obtain a first elastomeric compound which is subsequently fed to a multi-shaft continuous mixing device, so as to obtain a second elastomeric compound.
- the compounding process and plant according to aspects of the present invention may be employed to produce an elastomeric compound comprising any kind of elastomeric polymers, as well as any kind of reinforcing fillers, usually used in the tyre manufacturing.
- the elastomeric polymers may be selected, for example, from diene elastomeric polymers and mono-olefin elastomeric polymers, or mixtures thereof.
- Diene elastomeric polymers may be selected, for example, from elastomeric polymers or copolymers with an unsaturated chain having a glass transition temperature (T 9 ) generally below 20 0 C, preferably in the range from about 0°C to about -11O 0 C.
- T 9 glass transition temperature
- These polymers or copolymers may be of natural origin or may be obtained by solution polymerization, emulsion polymerization or gas-phase polymerization of one or more conjugated diolefins, optionally blended with at least one comonomer selected from monovinylarenes and/or polar comonomers.
- the obtained polymers or copolymers contain said at least one comonomer selected from monovinylarenes and/or polar comonomers in an amount of not more than 60% by weight.
- diene elastomeric polymers are: cis-1 ,4-polyisoprene (either natural or synthetic, preferably natural rubber), 3,4-polyisoprene, poly-1 ,3-butadiene (in particular, high vinyl poly-1 ,3-butadiene having a content of 1 ,2-polymerized untis from about 15% to about 85% by weight), polychloroprene, optionally halogenated isoprene/isobutene copolymers, 1 ,3-butadiene/acrylonitrile copolymers, 1 ,3-butadiene/styrene copolymers, 1 ,3-butadiene/isoprene copolymers, isoprene/styren
- mono-olefin elastomeric polymers they may be selected, for example, from: copolymers of ethylene with at least one alpha-olefin having from 3 to 12 carbon atoms, and optionally with a diene having from 4 to 12 carbon atoms; polyisobutene; copolymers of isobutene with at least one diene.
- Particularly preferred are: ethylene/propylene copolymers (EPR); ethylene/propylene/diene terpolymers (EPDM); polyisobutene; butyl rubbers; halobutyl rubbers; or mixtures thereof.
- said at least one reinforcing filler may be selected, for example, from: carbon black, silica, alumina, aluminosilicates, calcium carbonate, kaolin, or mixtures thereof.
- the elastomeric compound may advantageously incorporate a coupling agent capable of interacting with silica and of linking it to the elastomeric polymer(s) during the vulcanization.
- a coupling agent capable of interacting with silica and of linking it to the elastomeric polymer(s) during the vulcanization.
- the coupling agents that are particularly preferred are bis(3-triethoxysilylpropyl)-tetrasulphide, or bis(3-triethoxysilylpropyl)disulphide.
- Said coupling agents may be used as such or as a suitable mixture with an inert filler (for example, carbon black) so as to facilitate their incorporation into the elastomeric compound.
- Fig.1 is a graph showing a throughput T (measured in kg/h) versus the screw diameter D (measured in mm) obtainable for a typical viscous elastomeric compound at the output of different types of multi-shaft continuous mixing devices;
- Figure 2 schematically shows a transverse section of a ring extruder usable in a compounding plant according to an embodiment of the present invention
- Figures 3-6 show schematic diagrams of plants for producing an elastomeric compound according to exemplary embodiments of the present invention.
- a high quality elastomeric compound can be obtained in a compounding plant of reduced complexity by producing the elastomeric compound with at least one mixing step carried out in at least one batch mixing device and at least one mixing step carried out in at least one continuous mixing device.
- FIG 1 a graph showing the throughput T (measured in kg/h) obtainable for a typical viscous elastomeric compound at the output of various types of multi-shaft continuous mixing devices when processing elastomeric materials, versus the diameter of the screws used in such multi-shaft continuous mixing devices.
- the graph of figure 1 shows the throughput versus the screw diameter of a twin screw extruder (TSE, solid line), of a ring extruder having twelve screws disposed along a ring (RE 12, dash-dot line), of a ring extruder having twenty-four screws disposed along a ring (RE 24, dashed line), of a ring extruder having thirty-six screws disposed along a ring (RE 36, dotted line).
- TSE twin screw extruder
- the graph was obtained by the Applicant in part by fitting experimental data, and in part by simulation.
- the trend related to the TSE is a fit of experimental throughput data obtained by the Applicant using different twin screw extruders (i.e. multi-shaft continuous mixing devices having two co-rotating parallel screws) for processing a rubber compound comprising carbon black as reinforcing filler, i.e. a typical mixture for use in the tyre industry.
- twin screw extruders i.e. multi-shaft continuous mixing devices having two co-rotating parallel screws
- the following general fitting formula was written for fitting the TSE data trend, which could be written as:
- T 0 corresponds to the throughput obtainable at a screw diameter D 0 .
- the experimental data were fitted by using a parameter ⁇ of about 2. Such value could be even lower for other elastomeric compounds.
- the trends for the different ring extruders are the result of a simulation performed by the Applicant.
- the low growth of the throughput trend for a twin screw continuous mixing device in the processing of elastomeric materials principally depends on the fact that the elastomeric material must be "gently" worked (i.e. at relatively low screw rotation speed, and/or at relatively low shear rate, and/or at relatively low energy, etc.), in order to keep a low temperature of the compound being mixed within the screw channels, to prevent premature scorching of the compound. Since typical batch mixing devices used in compounding plants of industrial tyre production sites have minimum throughputs of about 1000 kg/h (or much more, for massive compound production), the throughput result shown in Figure 1 for the twin screw extruder (solid line) highlights that the coupling of a batch mixing device and of a twin screw extruder may become problematic.
- the graph of Figure 1 thus pratically shows that in order to produce elastomeric compounds with both a high quality and a high throughput, compatible with a tyre production on industrial scale, a compounding plant comprising at least one batch mixing device and continuous mixing devices having only two shafts does not represent an advantageous (and in some cases a feasible) solution.
- a different result is inferred when considering, in figure 1 , the throughput trends of ring extruders.
- a throughput of at least 500 kg/h for a typical elastomeric compound to be used for manufacturing tyres can be obtained by a ring extruder having twelve screws of about 50-60 mm in diameter (see dash-dot line), i.e.
- a ring extruder comprising six screws (for which the throughput trend is not explicitly shown in figure 1 , but that is located somewhere in the middle between the solid line related to the twin screw extruder and to the ring extruder having twelve screws) could be able to obtain a throughput of about 500 kg/h by using a screw diameter of about 80 mm, still in an acceptable range of feasibility, compactness and cost of the machine.
- a compounding plant using batch mixing devices in combination with multi-shafts continuous mixing devices having at least six rotating screws can phase and balance its production of high quality elastomeric compound for tyres on high throughputs, compatible with a tyre production on industrial scale.
- ring extruders which are able to give additional advantages in terms of machine compactness (particularly in length, under the same diameter), and degassing capability.
- a ring extruder (200) comprises:
- the plurality of screws (204) rotatably mounted on respective shafts within said annular chamber (203), to form a ring.
- the plurality of screws are co-rotating and at least partially (preferably fully) intermeshed.
- the screws (204) intensely mix the elastomeric compound (205) within the annular chamber (203), and the elastomeric compound moves from one screw channel to the other in a high number of intermeshing regions, so as to increase the heat exchange with the housing surface.
- self-wipening screws are used in the ring extruders.
- a ring extruder also typically comprises gas outlet openings (not shown in figure 2) provided in the outer housing, to allow removal of volatile material. Vacuum can be advantageously applied to said gas outlet openings, to further facilitate extraction of volatile material.
- Exemplary embodiments of ring extruders which can be applied for the purposes of the present invention are sold by Extricom GmbH.
- US patent no. 5836682 and US patent application 2007/0121421 are exemplary documents related to ring extruders.
- a number of embodiments for a compounding plant comprising at least one batch mixing device and at least one multi-shaft continuous mixing device will be described.
- a ring extruder will be used as exemplary continuous mixing device having a high number of shafts.
- a compounding plant (100) for producing an elastomeric compound according to the present invention includes a mixing apparatus (101a) comprising an internal mixer (101 ) (e.g. a Banbury ® mixer) wherein the elastomeric polymer(s) (102) and the reinforcing filler(s) (103) are fed.
- a mixing apparatus 101a
- an internal mixer 101
- e.g. a Banbury ® mixer e.g. a Banbury ® mixer
- all the remaining components of the elastomeric compound e.g. vulcanizing agents, activators, accelerators, or the other additives optionally present
- the internal mixer (101) may be fed to the elastomeric compound.
- the mixing into said internal mixer (101) may be carried out in at least two steps.
- the obtained first elastomeric compound (104) is fed to the ring extruder (106) through a feed hopper (105).
- the mixing extruder (106) of figure 3 shows only one feed hopper (105). However, particularly in the case when all the components of the elastomeric compound (e.g. vulcanizing agents, activators, accelerators, or the other additives optionally present) are not fed to the internal mixer (101 ), more than one feed hopper (not represented in figure 3), may be present along the ring extruder (106). Moreover, the ring extruder (106) may be provided with gravimetically controlled feeding pumps (not represented in figure 3) which are useful to introduce into the ring extruder (106) additional components such as, for example, plasticizing oils.
- additional components such as, for example, plasticizing oils.
- the mixing within the ring extruder (106) produces a second elastomeric compound.
- the second elastomeric compound (108) is discharged from the mixing extruder (106), e.g. in the form of a continuous ribbon or sheet, by pumping it through a roller die (107), for example by means of a gear pump (not shown in figure 3), and is subsequently cooled, preferably to room temperature, by passing it through a cooling device (109).
- a fixed die (not shown in figure 3) can also be used in place of the roller die (107).
- the second elastomeric compound (108) may be obtained in the form of a subdivided product by pumping it through an extruder die (not represented in figure 3), said extruder die being provided with a perforated die plate equipped with knives.
- the obtained product in subdivided form is subsequently cooled, preferably to room temperature, e.g. by conveying it to a cooling device (not represented in figure 3).
- the second elastomeric compound (108) can be discharged through an open head (not shown in figure 3).
- the second elastomeric compound (108) may be obtained directly in the form of a semi-finished product to be used in the assembling of a green tyre.
- an extrusion die having a predefined opening shape and equipped with a knife can be used (not shown in figure 3).
- structural elements obtainable in such way could be the following ones: bead filler, sidewall, tread band, liner, underliner, antiabrasive layer.
- a continuous strip-like element to be used for forming structural elements of green tyres by plural windings on a support e.g. a manufacturing drum
- a support e.g. a manufacturing drum
- Figure 4 shows a further embodiment of a plant (200) for producing an elastomeric compound according to the present invention: the same reference numbers have been used for the corresponding elements disclosed in figure 3.
- the second elastomeric compound (108) is fed to a further internal mixer (201) (e.g. a Banbury ® mixer).
- the feeding to said further internal mixer (201 ) may be particularly useful when not all the components of the elastomeric compound are fed to the internal mixer (101).
- the vulcanizing agents, and/or the activators, and/or the accelerators may be fed to said further internal mixer (201 ).
- (108) is cooled, preferably to room temperature, by passing it through a cooling device
- the second elastomeric compound (108) may be directly fed, without being cooled, to said further internal mixer (201) (not represented in figure 4).
- the second elastomeric compound (108) may be obtained in the form of a subdivided product as disclosed above and subsequently fed to said further internal mixer (201 ) (not represented in figure 4).
- Figure 5 shows a further embodiment of the plant (300) for producing an elastomeric compound according to the present invention: the same reference numbers have been used for the same elements as those disclosed in figure 3.
- a mixing apparatus (101a) comprising an internal mixer (101 ) and a conveying extruder (301) is represented.
- the first elastomeric compound (104) is fed to a conveying extruder (301) (e.g. a single helical screw extruder) through a feed hopper (302).
- the feeding to said one conveying extruder (301) may allow to control the feeding rate of said first elastomeric compound (104) to the ring extruder (106).
- the first elastomeric compound (104) is directly fed to the conveying extruder (301).
- the first elastomeric compound (104) is directly fed from said conveying extruder (301) to the ring extruder (106), through a feed hopper (105) e.g. in the form of a continuous ribbon, by pumping it through a roller die (303), for example by means of a gear pump (not represented in figure 5).
- the first elastomeric compound (104) is firstly cooled, preferably to room temperature, at the exit from the conveying extruder (301), by passing it through a cooling device before feeding it to the ring extruder (106). Said cooling may be useful in order to increase the viscosity of said first elastomeric compound before feeding it to said ring extruder (106), thus allowing a better mixing of said first elastomeric composition into said ring extruder (106).
- the first elastomeric compound (104), at the exit from the conveying extruder (301), after having been cooled by passing it through the cooling device, may be reduced in the form of a subdivided product by means of a cutting device (e.g. a mill provided with rotating blades) before being fed to the ring extruder (106).
- a cutting device e.g. a mill provided with rotating blades
- the feeding to the ring extruder (106) may be controlled by means of feeders (e.g. volumetric or loss-in-weight feeders) (not shown in figure 5).
- said conveying extruder (301) may be equipped with: an extruder die provided with a perforated die plate equipped with knives in order to obtain said first elastomeric compound in the form of a subdivided product before feeding it to said mixing extruder (106) (not shown in figure 5); or an open head in order to allow said first elastomeric compound to directly flow into said ring extruder (106) (not shown in figure 5).
- said conveying extruder (301) may be replaced with an open mill mixer (not shown in figure 5).
- an open mill mixer may be placed between said internal mixer (101) and said conveying extruder (301) (not shown in figure 5).
- a further internal mixer e.g. a Banbury ® mixer
- a further internal mixer can be used downstream of the ring extruder (501 ), collecting the second elastomeric compound exiting from the ring extruder (106), in a similar manner to that shown in figure 4.
- Figure 6 shows a portion of a further embodiment of the plant (600) for producing an elastomeric compound according to the present invention: the same reference numbers have the same meanings as disclosed in the previous figures 3-5.
- the second elastomeric compound (108) is fed to an extruder (601) (e.g. a cold feed single screw extruder) for manufacturing a semi-finished product, through a feed hopper (602), after cooling through a cooling device (109).
- an extruder e.g. a cold feed single screw extruder
- the second elastomeric compound is directly fed to the feed hopper (602) of a hot feed single screw extruder, without cooling.
- the second elastomeric compound is discharged from the extruder (601) in the form of a sheet or in the form of a semi-finished product useful in tire manufacturing (such as those mentioned above) (603), by pumping it through an extrusion die (not shown in figure 6).
- the second elastomeric compound (108) is discharged from the extruder (601 ) in the form of a sheet or in the form of a semi-finished product useful in tire manufacturing (603), by pumping it through a roller die (not represented in figure 6).
- the obtained sheet or semi-finished product (603) is subsequently subjected to a cooling treatment, usually by means of water and/or forced air.
- the sheet or semifinished product (603) thus treated is then usually arranged on benches or on bobbins waiting for further processing.
- a continuous elongated strip-like element (not shown in figure 6) may be obtained from the extruder (601) which may be directly used, without being stored, in tire manufacturing, operating as disclosed above.
- NR natural rubber (STR20 - Taiteck Rubber);
- BR polybutadiene (Europrene Neocis ® BR40 - Polimeri Europa);
- N326 carbon black
- Antioxidant phenyl-p-phenylenediamine (6-PPD - Akzo Nobel);
- HMMM hexamethoxymethylmelamine
- PVI flameant: N-cyclohexylthiophthalimide (Santogard ® PVI - Flexys);
- DCBS insectator: benzothiazyl-2-dicyclohexylsulphenamide (Vulkacit ® DZ/EGC
- the elastomeric compound was prepared by using a two-step conventional mixing in a
- the elastomeric compound obtained in 1 st step was cooled to room temperature (23°C) and subsequently fed to the same Banbury ® mixer above disclosed and a further mixing was carried out operating at the following working conditions: feeding: 200 kg; temperature: 30 0 C; mixing time: 130 seconds; fill factor: 65%; rotor speed: 40 rpm; discharge temperature: 105 0 C.
- the obtained elastomeric compound was subsequently cooled to room temperature (23°C).
- the elastomeric compound was produced by using a plant according to figure 5. To this aim, the elastomeric compound obtained according to Example 1 and discharged from the Banbury ® mixer was directly fed (without cooling) to a single screw extruder, operating at the following working conditions: feeding rate: 5500 kg/h; screw speed: 25 rpm; temperature profile: 25°C; elastomeric compound temperature measured at extruder discharge: 105°C.
- the elastomeric compound discharged from the conveying extruder was cooled to room temperature (23 0 C) and subsequently fed to a ring extruder Extricom RE® 3 XP having a nominal screw diameter of 30 mm, operating at the following working conditions: feeding rate: 165 kg/h; screw speed: 105 rpm; torque: 90%; real temperature profile: 32-35-54-24-42-31-21 0 C; elastomeric compound temperature measured at extruder discharge: 120°C. melt pressure at die: 24 bar
- the elastomeric compound discharged from the ring extruder was subsequently cooled to room temperature (23°C).
- the Mooney viscosity ML(1 +4) at 100°C of the non-crosslinked compounds was measured according to Standard ISO 289-1 :1994.
- the modulus (100% Modulus), the stress at break, as well as the elongation at break, were measured according to Standard ISO 37:2005 on samples of the abovementioned elastomeric compounds vulcanized at 170 0 C, for 10 min.
- the hardness in IRHD degrees (at 23°C) according to Standard ISO 48:1994 was measured on samples of the abovementioned elastomeric compounds vulcanized at 170 0 C, foMO min.
- Dynamic mechanical properties were measured using an lnstron dynamic device in the traction-compression mode according to the following methods.
- the dynamic mechanical properties are expressed in terms of dynamic elastic modulus (E') and Tan delta (loss factor) values.
- the Tan delta value is calculated as a ratio between viscous modulus (E") and elastic modulus (E').
- the filler dispersion was measured according to Standard ISO 11345:2006.
- test piece of crosslinked elastomeric compounds (vulcanized at 170 0 C, for 10 min) having the following dimension: 4 mm x 4 mm, was used to evaluate both the filler dispersion (X value) and the filler distribution (Y value) by using a DisperGrader Model 1000NT with 100x magnification, (TECH PRO Corp.).
- This model has several scales available for comparison. The scale that was selected for these test was the RCB scale. This scale is typically used for measurement of elastomeric compounds filled with reinforcing carbon black.
- Ten reference pictures are used for determining the filler dispersion (X value). An algorithm has been derived using these reference pictures and is then applied to an unknown sample. The DisperGrader then analyzes an unknown sample and automatically assigns a dispersion value (X value) to the unknown sample. Higher dispersion values (X values) represent better dispersion.
- the Y value is not based on visual comparison against photographic standards, but based on the actual size and number of large agglomerates.
- a high rating value means that there are no agglomerates higher than 23 ⁇ m in average diameter are present in the tested areas.
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Abstract
Description
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Priority Applications (7)
Application Number | Priority Date | Filing Date | Title |
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US13/141,633 US8858852B2 (en) | 2008-12-23 | 2008-12-23 | Process and plant for producing tyres |
PCT/IT2008/000794 WO2010073275A1 (en) | 2008-12-23 | 2008-12-23 | Process and plant for producing tyres |
CN2008801326491A CN102281999A (en) | 2008-12-23 | 2008-12-23 | Process and plant for producing tyres |
EP08876145.7A EP2379294B9 (en) | 2008-12-23 | 2008-12-23 | Process and plant for producing tyres |
RU2011130905/05A RU2475356C1 (en) | 2008-12-23 | 2008-12-23 | Method and machine for making tires |
BRPI0823386-1A BRPI0823386B1 (en) | 2008-12-23 | 2008-12-23 | PROCESSES AND FACILITIES TO MANUFACTURE A TIRE, AND TO PRODUCE AN ELASTOMERIC COMPOUND |
US14/243,606 US9365006B2 (en) | 2008-12-23 | 2014-04-02 | Process and plant for producing tyres |
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PCT/IT2008/000794 WO2010073275A1 (en) | 2008-12-23 | 2008-12-23 | Process and plant for producing tyres |
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US13/141,633 A-371-Of-International US8858852B2 (en) | 2008-12-23 | 2008-12-23 | Process and plant for producing tyres |
US14/243,606 Division US9365006B2 (en) | 2008-12-23 | 2014-04-02 | Process and plant for producing tyres |
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WO2010073275A1 true WO2010073275A1 (en) | 2010-07-01 |
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US (2) | US8858852B2 (en) |
EP (1) | EP2379294B9 (en) |
CN (1) | CN102281999A (en) |
BR (1) | BRPI0823386B1 (en) |
RU (1) | RU2475356C1 (en) |
WO (1) | WO2010073275A1 (en) |
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WO2012085714A1 (en) * | 2010-12-22 | 2012-06-28 | Pirelli Tyre S.P.A. | Method and apparatus for producing tyres |
CN102602014A (en) * | 2012-03-07 | 2012-07-25 | 黄加源 | Manufacturing process for colorful tires |
EP2607049A1 (en) | 2011-12-22 | 2013-06-26 | The Goodyear Tire & Rubber Company | Apparatus and process for mixing rubber compounds |
EP2607037A1 (en) | 2011-12-22 | 2013-06-26 | The Goodyear Tire & Rubber Company | Apparatus and process for mixing rubber compounds |
WO2014191953A1 (en) * | 2013-05-30 | 2014-12-04 | Pirelli Tyre S.P.A. | Process for producing tyres for vehicle wheels |
DE102015120586A1 (en) * | 2015-09-08 | 2017-03-09 | Blach Verwaltungs Gmbh & Co. Kg | Ring extruder for the continuous preparation of rubber compounds with co-extruder and cooling system |
DE102015120583A1 (en) * | 2015-09-08 | 2017-03-09 | Blach Verwaltungs GmbH + Co. KG | Ring extruder for continuous preparation of rubber compounds with co-extruder |
EP2516131B1 (en) * | 2009-12-22 | 2018-05-30 | Pirelli Tyre S.p.A. | Extrusion process and device for producing elastomeric compounds |
CN108349112A (en) * | 2015-12-04 | 2018-07-31 | 倍耐力轮胎股份公司 | The preparation method of elastomer blend |
US10668679B2 (en) | 2014-12-29 | 2020-06-02 | Pirelli Tyre S.P.A. | Process for producing tyres |
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EP2219837B1 (en) * | 2007-11-13 | 2013-08-14 | Pirelli Tyre S.P.A. | Process for manufacturing a tire |
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- 2008-12-23 US US13/141,633 patent/US8858852B2/en active Active
- 2008-12-23 WO PCT/IT2008/000794 patent/WO2010073275A1/en active Application Filing
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Publication number | Priority date | Publication date | Assignee | Title |
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EP2516131B1 (en) * | 2009-12-22 | 2018-05-30 | Pirelli Tyre S.p.A. | Extrusion process and device for producing elastomeric compounds |
RU2592528C2 (en) * | 2010-12-22 | 2016-07-20 | Пирелли Тайр С.П.А. | Method and device for producing tyres |
CN103249534A (en) * | 2010-12-22 | 2013-08-14 | 倍耐力轮胎股份公司 | Method and apparatus for producing tyres |
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CN102602014A (en) * | 2012-03-07 | 2012-07-25 | 黄加源 | Manufacturing process for colorful tires |
WO2014191953A1 (en) * | 2013-05-30 | 2014-12-04 | Pirelli Tyre S.P.A. | Process for producing tyres for vehicle wheels |
US10668679B2 (en) | 2014-12-29 | 2020-06-02 | Pirelli Tyre S.P.A. | Process for producing tyres |
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CN108349112A (en) * | 2015-12-04 | 2018-07-31 | 倍耐力轮胎股份公司 | The preparation method of elastomer blend |
Also Published As
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US20120025430A1 (en) | 2012-02-02 |
RU2475356C1 (en) | 2013-02-20 |
BRPI0823386B1 (en) | 2020-09-29 |
EP2379294A1 (en) | 2011-10-26 |
BRPI0823386A2 (en) | 2019-10-08 |
EP2379294B9 (en) | 2013-11-13 |
US8858852B2 (en) | 2014-10-14 |
US20140227379A1 (en) | 2014-08-14 |
EP2379294B1 (en) | 2013-02-13 |
CN102281999A (en) | 2011-12-14 |
US9365006B2 (en) | 2016-06-14 |
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