RU2462358C2 - Method and plant for producing elastomer compound - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to production of elastomer compound. Method of producing tire comprises making assembled uncured tire with set of structural elements, subjecting it to moulding and cross-linking to make finished tire. One of said structural elements comprises elastomer compound produced in the following steps. Feeding one elastomer polymer 102 selected from diene elastomer polymer and monoolefin elastomer polymer or mix thereof, one reinforcing filler 103 and curing agents in at least one intermittent-action mixer 101. Note that said intermittent-action mixer 101 incorporates two-opposite-rotation screws. Mixing in said mixer 101 is performed at rotor rpm about 20 to 60. Mixing and dispersing of aforesaid reinforcing filler 103 in said elastomer polymer 102 in mixing device 101a to produce elastomer compound 104, 108. Unloading said compound and feeding it in continuous-action mixer 106. Note here that said continuous mixer comprises to revolving screws. Mixing said elastomer compound 104, 108 in said continuous mixer 106. Unloading said elastomer compound 104, 108 from said continuous mixer 106.

EFFECT: better dispersion, good mechanical properties.

Description

FIELD OF THE INVENTION

The present invention relates to a method and apparatus for producing an elastomeric compound.

More specifically, the present invention relates to a method for producing an elastomeric compound comprising 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, moreover, the resulting elastomeric compound is mainly, but not exclusively, intended for use in the manufacture of tires.

Moreover, the present invention also relates to a plant for producing an elastomeric compound comprising at least one batch mixing device and at least one continuous mixing device.

State of the art

Traditionally, the preparation of elastomeric compounds is carried out in batch mode using batch mixing devices, for example, internal mixers, for example, such as Banbury ^® mixers, having two rotors rotating in opposite directions, which provide an intensive mixing action for plasticizing the elastomeric polymer (s) ( -rov) and for introducing and thoroughly dispersing in such (-out) other components usually present in elastomeric compounds, for example, such as reinforcing fillers, lubricants, refining additives and other additives.

In the preparation of elastomeric compounds using internal mixers, numerous disadvantages are manifested, in particular poor heat dissipation and thereby poor temperature control, mainly due to the unfavorable ratio between the volume of material and the surface area of the mixer. To improve dispersion in the elastomeric polymer (s), a variety of components, and especially reinforcing fillers, are typically introduced into the elastomeric polymer (s) in loading batches distributed over multiple mixing operations separated by cooling steps and storage. Typically, heat-sensitive components, such as crosslinking agents and accelerators, are added only during the final mixing stage, after cooling the elastomeric compounds below a predetermined temperature (usually below 110 ° C), to avoid premature crosslinking (the phenomenon of “scorching” (“ undervulcanization ")).

Therefore, the production of elastomeric compounds using batch mixing devices, although still the most widely used production method in the rubber industry, requires a lot of time and energy and does not guarantee effective control of the properties of the obtained elastomeric compounds, especially with respect to the uniformity of dispersion of reinforcing fillers in elastomeric polymer (s). All such factors as variation in the added amounts of individual components, time regime of adding and unloading from mixers, initial temperature of raw materials and fluctuation of shear loads inside the material during mixing, contribute to the variation of properties from batch to batch.

In order to overcome the above limitations of batch processes, numerous attempts have been made in the rubber industry to develop production methods based on extrusion methods similar to those traditionally used in the processing of thermoplastic polymeric materials. Production processes carried out using an extruder should improve the uniformity of the properties of the obtained elastomeric compounds, provide better thermal control due to more perfect surface-to-mass ratios, and create the possibility of developing highly automated operations. For an overview of this topic, see H. Ellwood's article, “A tale of continuous development,” published in the European Rubber Journal, March 1987, pages 26-28.

United States Patent US 4,897,236 provides a method and apparatus for continuously producing a rubber mixture in which the ingredients of the mixture are fed, plasticized and homogenized in a twin screw extruder. The resulting mixture is divided into first and second parts. The first part is discharged, while the second part is recycled for additional homogenization and for mixing with fresh portions of the ingredients fed to the extruder. The reused portion is circulated and returned from the cooled annular chamber located outside the extruder chamber, said annular chamber having outlet and inlet channels connected to the inside of the extruder. This partial recirculation of the rubber mixture should compensate for fluctuations in the dosage of ingredients and local inhomogeneities that may occur. Moreover, intensive cooling of the recirculating part in the annular chamber should correct the increasing operating temperature and should improve the dispersing effect due to increased shear stresses due to lower temperatures.

United States Patent US 5,626,420 discloses a method and apparatus for continuous mixing in which the base elastomer (s) and other components are continuously metered and introduced into a mixing chamber formed of a stator and a rotor rotating in such, preferably in a single screw extruder . The introduced components move forward inside the mixing chamber along the punching and mixing zones. To improve the dispersion and homogenization of the rubber components, the degree of filling of the mixing chamber, at least in certain mixing zones, is less than 1. For proper introduction of the components, and especially the base rubber, forced delivery devices such as positive displacement pumps are used in the mixing chamber (e.g. gear pumps). To ensure accurate dosing of the various components, it may be desirable to add components in the mixing zone, where the degree of filling is 1, located between two mixing zones having a degree of filling lower than 1.

United States Patent US 6,726,352 discloses a method for processing a rubber mixture or compound for making tires, comprising the steps of determining allowable deviations from the control values of the process parameters, registering the values of the process parameters, comparing the recorded values of the process parameters with the control values and allowable deviations, evaluating the processing quality of the obtained semi-finished product depending on the compliance or non-compliance of the recorded values with the control value pits and tolerances, the resulting semi-finished product qualification based on an assessment of quality of treatment and the decision on the next stage of processing the obtained semifinished product, depending on the qualifications of the resulting semi-finished product. The treatment includes at least one mixing cycle and an extrusion cycle to obtain a semi-finished product as a product. The specified mixing cycle is preferably carried out in at least one mixer, comprising a pair of rotors that act tangentially relative to each other, or with interpenetration, for example, such as Banbury ^® or Intermix ^® mixers. Cycles are controlled by process parameters recorded during the execution of cycles.

SUMMARY OF THE INVENTION

From the Applicant’s point of view, one of the most important aspects in obtaining elastomeric compounds using continuous mixing devices, such as extruders, is the system for supplying all components of elastomeric compounds to continuous mixing devices. In fact, these components must be processed (for example, granular, pelletized, ground, etc.) and accurately metered to be fed into continuous mixing devices. From these considerations, a complex supply system should be provided, which leads to an increase in the overall duration of the production process, as well as an increase in production costs.

On the other hand, the Applicant has noted that dispersion of components that are usually added to elastomeric compounds, in particular dispersion of reinforcing fillers using batch mixing devices, may be unsatisfactory.

However, an increase in the number of mixing stages in batch mixing devices in order to improve the dispersion of components in elastomeric compounds can generally result in numerous disadvantages, for example, damage to the elastomeric polymer (s), deterioration of the mechanical properties of elastomeric compounds, premature stitching (the phenomenon of "scorching") of elastomeric compounds.

The applicant has faced the problem of creating a more efficient method for producing elastomeric compounds, which reduces the number of mixing stages, which elastomeric compounds are usually subjected to when the process is carried out using batch mixing devices, as well as reducing or even eliminating obstacles that may arise when the process is carried out with using continuous mixing devices.

In particular, the Applicant faced the problem of creating a method for producing an elastomeric compound in which improved dispersion of these components, in particular reinforcing fillers, can be achieved without adversely affecting the mechanical properties (both static and dynamic) of the obtained elastomeric compound.

Now, the Applicant has unexpectedly discovered that the above properties can be obtained by producing an elastomeric compound in at least one mixing stage, carried out in at least one batch mixing device, and in at least one mixing stage, carried out in at least one continuous mixing device.

Moreover, the Applicant has found that this method allows to reduce the mixing time, thereby increasing productivity and lowering production costs.

For the purposes of the present description and the following claims, the term “batch mixing device” means a mixing device into which the components of an elastomeric compound are fed periodically in predetermined quantities (in batches) and mixed for a predetermined time so as to obtain an elastomeric compound. At the end of the mixing step, the resulting elastomeric compound is completely discharged from the mixing device.

For the purposes of the present description and the following claims, the term “continuous mixing device” means a mixing device to which the components of the elastomeric compound are fed continuously (except for the possible stop of the mixing device for maintenance or to change the composition of the elastomeric compound) and from which the elastomeric compound is withdrawn continuous flow, in contrast to the periodic loading / unloading of a batch mixing device.

According to a first aspect, the present invention relates to a method for producing an elastomeric compound, comprising:

- supply of at least one elastomeric polymer and at least one reinforcing filler in a mixing device comprising at least one batch mixing device;

- mixing and dispersing in said at least one mixing device of said at least one reinforcing filler in said at least one elastomeric polymer so as to obtain a first elastomeric compound;

- unloading the specified first elastomeric compound from the specified at least one mixing device;

- feeding said first elastomeric compound into at least one continuous mixing device, said mixing device comprising at least two rotating screws;

- mixing said first elastomeric compound in said at least one continuous mixing device so as to obtain a second elastomeric compound;

- the removal of the specified second elastomeric compound from the specified at least one continuous mixing device.

Applicant has found that said second elastomeric compound shows a significantly improved dispersion of said at least one reinforcing filler relative to said first elastomeric compound, along with the absence of any deterioration or even improvement in mechanical properties (both static and dynamic).

According to another preferred embodiment, said method may be executed in continuous or batch mode.

When this method is carried out in continuous mode, the first elastomeric compound is directly fed into said at least one continuous mixing device without intermediate storage.

When said method is carried out in batch mode, said first elastomeric compound is fed into said at least one continuous mixing device after storage.

According to a further aspect, the present invention relates to an apparatus for producing an elastomeric compound, comprising:

at least one mixing device comprising at least one batch mixing device, said mixing device being adapted to produce a first elastomeric compound;

at least one continuous mixing device, said continuous mixing device comprising at least two rotary screws, said continuous mixing device adapted to receive said first elastomeric compound and to obtain a second elastomeric compound.

According to a further aspect, the present invention relates to a method for manufacturing a tire, comprising:

- the manufacture of assembled, but not vulcanized tires, including many structural elements, and these structural elements include suitable for stitching elastomeric compound;

- subjecting the assembled but not vulcanized tire to molding and stitching to form a finished tire;

in which at least one of these structural elements includes the specified second elastomeric compound, and the specified second elastomeric compound is obtained by the method according to the first aspect of the present invention.

The present invention, in at least one of the aforementioned aspects, may exhibit one or more of the preferred features disclosed below.

According to one preferred embodiment, said batch mixer is selected from internal mixers, open type mixers. Particularly preferred are internal mixers.

Typically, said batch mixing device includes a pair of rotors that act tangentially relative to each other or are interpenetrating.

Typically, said batch mixing device includes a mixing chamber containing a pair of rotors inside which rotate in opposite directions so as to mix the components introduced into the mixing chamber from the top thereof.

For this purpose, said batch mixing device is usually equipped with a pneumatic or hydraulic cylinder located in the upper part of the mixing chamber, and a plunger that can move up to open the mixing chamber, thereby allowing components to be introduced through special loading funnels and down to create pressure on the material processed by the rotors, and located above those.

A hydraulic system located in the bottom of the mixing chamber allows the elastomeric compound to be discharged at the end of the mixing cycle by opening a suitable outlet channel.

Specific examples of internal mixers, which can be advantageously used according to the present invention are those known under the trade name Banbury ^® (Banbury) or Intermix ^® (Intermiks), depending on whether the rotors operate tangentially relative to each other or are interpenetrating. A Banbury ^® mixer is particularly preferred.

Specific examples of open-type mixers, which can be advantageously used according to the present invention, are: open-type mixer with runners, mixer with Z-shaped blades. An open-type mixer with runners is particularly preferred.

According to one preferred embodiment, mixing in said at least one batch mixing device can be carried out at a rotor speed of from about 20 rpm to about 60 rpm, preferably from about 30 rpm to about 50 rpm.

According to a further preferred embodiment, the mixing in said at least one batch mixing device can be carried out using a filling factor of the mixing chamber (the filling coefficient is a part of the total free volume of the mixing chamber occupied by the mixed material) not higher than about 80%, preferably from about 55% to about 70%. If too high a fill factor is chosen, the lack of free volume impedes material movement and mutual mixing, and proper mixing becomes impossible. Similarly, if only a very small fill factor is selected, it is difficult to ensure proper mixing with high shear loads and proper homogenization of the material in the mixing chamber.

According to one preferred embodiment, said at least one continuous mixing device has at least two unidirectionally rotating screws.

Said rotating screws may include high shear mixing elements, such as plasticizers; elements that are capable of redistributing materials, such as gear elements, gears or pins; flow restrictors, such as blisters, adjustable or fixed throttles, or screw turns with a shallow depth of turn. These elements can be arranged on two or more shafts that rotate around their axes in the same direction (unidirectional) or in opposite directions (antidirectional) relative to each other. Screw shafts can be parallel, converging or diverging. The rotational speeds of these shafts may be the same or different. The shafts of the screws can be spaced at different distances from each other so as to provide the totality of the elements on each shaft the ability to be in meshing to different degrees or not to be engaged at all. The orientation of each of the mixing elements (including whether the elements are left-handed or right-handed) is selected based on the degree of back reaction and / or pressure gradient and temperature / shear history required along the length of the extruder. Some variations in the design of plasticizers include single-chamber, two- or multi-start arrangements. The number of teeth on the gear or gear mixer may also vary.

Preferably, said at least two unidirectional screws are at least partially engaged. More preferably, said at least two unidirectional screws are substantially fully engaged.

According to a further preferred embodiment, said continuous mixing device is a mixing extruder.

Preferably, said mixing extruder comprises:

- a housing, said housing comprising at least one inlet and an outlet;

- at least two screws mounted rotatably in said housing.

According to a further preferred embodiment, said mixing extruder may be selected, for example, from: twin-screw extruders with unidirectional rotation; unidirectional multi-screw extruders, including more than two screws, such as, for example, ring extruders; roll planetary extruders. Unidirectional twin screw extruders or ring extruders are particularly preferred. Ring extruders are even more preferred.

According to a further preferred embodiment, said at least one mixing extruder is a self-cleaning multi-screw extruder with interlocking unidirectional screws.

According to a further preferred embodiment, said at least one mixing extruder is a self-cleaning twin screw extruder with interlocking unidirectional screws.

Typically, self-cleaning multi-screw or twin-screw extruders with intermeshing unidirectional screws include mixing elements of a single rotating screw, which are substantially fully engaged with the mixing elements of an adjacent rotating screw, thereby allowing self-cleaning of the extruder.

The use of the specified multi-screw or twin-screw extruder with unidirectional screws, which are essentially fully engaged, can provide the ability to achieve very good dispersion of the components, in particular reinforcing fillers, in the second elastomeric compounds.

According to one preferred embodiment, mixing in said at least one continuous mixing device can be carried out at screw speeds of from about 10 rpm to about 600 rpm, preferably from about 40 rpm to about 400 rpm.

It should be noted that the indicated screw rotation speed can allow achieving very good dispersion of the components, especially reinforcing fillers, in the second elastomeric compound, as well as avoiding premature crosslinking (the phenomenon of “scorching”) of the second elastomeric compound, which can occur if using too high a speed screw rotation.

According to a further embodiment, the method according to the present invention may include cooling said first elastomeric compound before feeding it to said at least one continuous mixing device. Preferably, said first elastomeric compound can be cooled to a temperature of from about 15 ° C to about 40 ° C, more preferably from about 20 ° C to about 25 ° C.

According to a further embodiment, said mixing device comprises at least one conveying extruder.

According to one preferred embodiment, said first elastomeric compound is fed into said at least one conveying extruder before being fed into said at least one continuous mixing device.

According to one preferred embodiment, said at least one conveying extruder comprises:

- a housing, said housing comprising at least one inlet and an outlet;

- at least one transporting element mounted for rotation in the specified housing.

For the purposes of the present description and the following claims, the term “conveying element” means an element that essentially does not perform a mixing action, but only carries the elastomeric compound along the length of the extruder. Typical conveying elements can be selected, for example, from elements that mainly provide axial movement of the material, such as spiral screws.

According to a further preferred embodiment, transportation in said at least one conveying extruder can be carried out at a rotational speed of the conveying element from about 10 rpm to about 60 rpm, preferably from about 20 rpm to about 35 rpm.

Feeding to said at least one conveying extruder may provide the ability to control the feed rate of said first elastomeric compound to said at least one continuous mixing device.

Preferably, said at least one conveying extruder is selected from extruders with one spiral screw, discharge extruders having two spiral screws rotating in opposite directions.

According to a further embodiment, said mixing device comprises at least one open type mixer.

According to a further embodiment, said mixing device includes at least one internal mixer and at least one open type mixer, said open type mixer being preferably arranged downstream of said at least one internal mixer.

According to a further embodiment, the method of the present invention may comprise supplying said second elastomeric compound to at least one additional batch mixing device. The specified at least one additional mixing device of periodic action can be selected from those presented above.

According to a further embodiment, the method according to the present invention may include supplying said second elastomeric compound to at least one additional continuous mixing device. The specified at least one additional continuous mixing device may be selected from those presented above.

According to a further embodiment, said at least one continuous mixing device may be placed upstream of the semifinished product manufacturing apparatus using said second elastomeric compound.

A device for manufacturing a semi-finished product can be selected from those known in the technology, for example, such as calendaring devices, extruders.

According to a further embodiment, said at least one continuous mixing device may be equipped with a roll head. In this case, the semi-finished product is obtained directly from the specified at least one continuous mixing device.

According to a further embodiment, said at least one continuous mixing device may be equipped with an extrusion head. In this case, the semi-finished product is obtained directly from the specified at least one continuous mixing device.

The specified semi-finished product can be, for example, one of the structural elements of the tire, for example, such as: carcass ply, belt, block bead strip, sidewall, tread band, sealing layer of a tubeless tire, lining, anti-abrasive layer. According to methods known in the technology, these structural elements can subsequently be assembled using suitable production equipment to produce a finished tire.

On the other hand, alternative methods for manufacturing a tire without using semi-finished products are known in the art.

In this regard, in the case of structural elements of a tire essentially constituted by an elastomeric compound, for example, such as a tire bead blocking block, a sidewall, a tread band, a sealing layer of a tubeless tire, a lining, an anti-abrasive layer, on an assembly stand supporting the tire being manufactured, stacking a continuous elongated ribbon-like element, wherein said continuous elongated ribbon-like element is arranged so as to form a plurality of consecutive turns from side to side and / or an overlay for the floor bus in the final configuration. Alternatively, in the case of structural members of a tire substantially constituted by an elastomeric compound and at least one filamentary reinforcing element, for example, such as a carcass ply, a belt, said continuous elongated ribbon-like element is associated with at least one filamentary reinforcing element to obtain semi-finished products in the form of a rubberized wire or ribbon-like element, comprising at least one filamentary reinforcing element, which is then laid on an assembly stand, bearing manufactured tire, from side to side and / or overlay, to obtain a tire in the final configuration thereof. The specified stand may be a rigid stand or may have a toroidal shape. Methods of this type can be disclosed, for example, in European Patent Applications EP 928 680 or EP 928 702 or in International Patent Application WO 01/36185.

The specified assembly stand can be selected, for example, from the following devices:

- an assembly drum having a substantially cylindrical shape supporting at least one layer of the carcass;

- a molding drum having a substantially toroidal configuration, wherein said molding drum preferably supports at least one layer of the carcass with at least one belt belt assembled with it;

- an auxiliary drum having a substantially cylindrical configuration, wherein said auxiliary drum preferably supports at least one belt belt;

- a rigid stand, preferably formed so as to substantially correspond to the inner surface of the formed finished tire.

According to a further embodiment, said at least one continuous mixing device may form said second elastomeric compound in the form of a continuous elongated ribbon-like element, which is then laid on an assembly stand, as described above, wherein said continuous mixing device is preferably equipped with a roll head or extrusion head . Alternatively, said continuous elongated ribbon-like element may be associated with at least one reinforcing threadlike reinforcing element.

The specified continuous elongated ribbon-like element, including the specified second elastomeric compound, may have a flattened cross section, for example, such as a rectangular, elliptical, or biconvex, or wedge-shaped. The cross-sectional dimensions of the specified continuous elongated ribbon-like element are significantly smaller than the cross-sectional dimensions of the manufactured structural element. By way of example, a continuous elongated ribbon-like element may have a width indicatively varying from about 3 mm to about 15 mm, and a thickness indicatively varying from about 0.5 mm to about 1.2 mm.

According to one preferred embodiment, all components of the elastomeric compound can be fed into said at least one mixing device.

In particular, in addition to the at least one elastomeric polymer and the at least one reinforcing filler, at least one of the following components can be added to the elastomeric compound:

- vulcanizing agents, for example, such as sulfur, or molecules containing sulfur (sulfur donors), or mixtures thereof;

activators, for example, such as zinc compounds, and in particular ZnO, ZnCO ₃ , zinc salts of saturated or unsaturated aliphatic acids containing from 8 to 18 carbon atoms, for example, such as zinc stearate, which are preferably formed in situ in an elastomeric compound from zinc oxide (ZnO) and aliphatic acid, and also BiO, PbO, Pb ₃ O ₄ , PbO ₂ , or a mixture thereof;

- accelerators, for example, such as dithiocarbamates, guanidine, thiourea, thiazoles, sulfenamides, thiurams, amines, xanthates or mixtures thereof;

- additives selected based on the particular application for which the composition is intended, for example, such as antioxidants, anti-aging agents, plasticizers (e.g. plasticizing oils), adhesives, antiozonants, modifying polymers or mixtures thereof.

The above list of components is provided only to illustrate some examples of the most commonly used components commonly used in elastomeric compounds, in particular in an elastomeric compound for the manufacture of tires, and should not be construed as limiting the scope of the present invention.

When all components of the elastomeric compound are fed into a batch mixer, for example an internal mixer, such as a Banbury ^® mixer, the mixing can preferably be carried out in at least two different stages, the first stage being an unproductive stage in which all components except those that can stimulate crosslinking (for example, sulfur and accelerators), are fed into said batch mixing apparatus, the second stage being roduktivnuyu step in which the elastomeric compound is obtained from said first step, and components capable of promoting crosslinking is fed into said mixer batch. The elastomeric compound thus obtained, that is, the first elastomeric compound, is then fed to a continuous mixing device, for example an extruder, to obtain a second elastomeric compound.

Alternatively, all components of the elastomeric compound, with the exception of components capable of promoting crosslinking, are fed to a batch mixer, for example an internal mixer, such as a Banbury ^® mixer, to produce a first elastomeric compound, which is then fed to a continuous mixer, such as an extruder, so that get a second elastomeric compound. The thus obtained second elastomeric compound, as well as the components capable of promoting cross-linking, and then fed to the auxiliary mixer batch, e.g. internal mixer, such as mixer Banbury ^®, which is disposed downstream relative to said continuous mixing device such as an extruder.

Alternatively, all components of the elastomeric compound, with the exception of components capable of promoting crosslinking is fed to the mixing apparatus periodic action, such as an internal mixer, such as mixer Banbury ^®, to produce a first elastomeric compound. The first elastomeric compound thus obtained, as well as components capable of promoting crosslinking, are then fed to a continuous mixing device, such as an extruder, to obtain a second elastomeric compound.

When an open type mixer is used as a batch mixing device, preferably all components of the elastomeric compound are fed into said open type mixer so as to obtain a first elastomeric compound, which is then fed to a continuous mixing device, for example an extruder, to obtain a second elastomeric compound.

The method according to the present invention can be used to obtain an elastomeric compound, including any kind of elastomeric polymers, in particular elastomeric polymers, as well as any type of reinforcing fillers commonly used in tire manufacturing.

Preferably, the elastomeric polymers can be selected, for example, from: diene elastomeric polymers, and monoolefin elastomeric polymers, or mixtures thereof.

Diene elastomers can be selected, for example, from elastomeric polymers or unsaturated chain copolymers having a glass transition temperature (T _g ) of substantially lower than 20 ° C, preferably in the range of from about 0 ° C to about -110 ° C. These polymers or copolymers may be of natural origin or may be prepared by solution polymerization, emulsion polymerization or gas phase polymerization of one or more conjugated diolefins, optionally mixed with at least one comonomer selected from monovinyl aromatic hydrocarbons and / or polar comonomers. Preferably, the resulting polymers or copolymers contain said at least one comonomer selected from monovinylated aromatic hydrocarbons and / or polar comonomers in an amount of not more than 60% by weight. Examples of diene elastomeric polymers are: cis-1,4-polyisoprene (either natural or synthetic, preferably natural rubber), 3,4-polyisoprene, poly-1,3-butadiene (in particular poly-1,3-butadiene with high vinyl group content, having a content of 1,2-polymerized structural units 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-styrene copolymers of isol, isoprene / 1,3-butadiene / styrene triple copolymers or mixtures thereof.

As for monoolefin elastomeric polymers, they can 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; isobutene copolymers with at least one diene. Particularly preferred are: ethylene-propylene copolymers (EPR); ethylene propylene diene triple copolymers (EPDM); polyisobutene; butyl rubbers; halogenated butyl rubbers or mixtures thereof.

Preferably, said at least one reinforcing filler may be selected, for example, from: carbon black, silica, alumina, aluminosilicates, calcium carbonate, kaolin, or mixtures thereof.

When a reinforcing filler comprising silica is present, the elastomeric compound may advantageously include a binder capable of reacting with silica and bonding it to the elastomeric polymer (s) during vulcanization. Particularly preferred binders include bis (3-triethoxysilylpropyl) tetrasulfide or bis (3-triethoxysilylpropyl) disulfide. These binders can be used as such or as a suitable mixture with an inert filler (e.g. carbon black) to facilitate their incorporation into the elastomeric compound.

Brief Description of the Drawings

The present invention will now be illustrated in more detail using illustrative embodiments, with the involvement of the accompanying figures, in which:

FIG. 1 is a schematic illustration of an apparatus for producing an elastomeric compound according to an embodiment of the present invention;

Figures 2-8 are schematic views of apparatus for producing an elastomeric compound according to further embodiments of the present invention;

FIG. 9a is a side view of two screws of a self-cleaning twin-screw extruder with unidirectional interlocking screws;

FIG. 9b shows cross-sectional views of two screws of a self-cleaning twin-screw extruder with unidirectional interlocking screws.

Detailed Description of Preferred Embodiments

With reference to FIG. 1, an apparatus (100) for producing an elastomeric compound according to the present invention includes a mixing device (101a) comprising an internal mixer (101) (e.g., a Banbury ^® mixer) into which elastomeric polymer (s) (102) are fed (102) and reinforcing filler (s) (103).

Preferably, all other components of the elastomeric compound (e.g., vulcanizing agents, activators, accelerators, or other additives present optionally) can be fed into the internal mixer (101).

Alternatively, mixing in said internal mixer (101) may be carried out in at least two stages.

After mixing, the obtained first elastomeric compound (104) is sent to a mixing extruder (106) (for example, a self-cleaning twin-screw extruder with unidirectional interlocking screws) through a feed funnel (105).

On the mixing extruder (106) in FIG. 1 shows only one feed hopper (105). However, especially in the case where all components of the elastomeric compound (for example, vulcanizing agents, activators, accelerators or other additives that are optionally present) are not fed into the internal mixer (101), more than one loading funnel (not shown in Fig. 1). Moreover, the mixing extruder (106) can be equipped with weight-controlled feed pumps (not shown in FIG. 1), which are suitable for introducing liquid components, such as plasticizing oils, into the mixing extruder (106).

Typically, the mixing extruder (106) may optionally be equipped with a degassing unit (110) to allow the escape of gases that may form during mixing of the elastomeric compound. Alternatively, more than one degassing unit (not shown in FIG. 1) may be present along the mixing extruder (106).

After mixing, the second elastomeric compound (108) is withdrawn from the mixing extruder (106), for example, in the form of a continuous tape, by forcing it through a roll head (107), for example, using a gear pump (not shown in Fig. 1), and then cooled, preferably to room temperature, by passing it through a cooling device (109).

Alternatively, the second elastomeric compound (108) can be obtained in the form of a divided product by injection through an extrusion die (not shown in FIG. 1), said extrusion die equipped with a perforated die plate equipped with knives using a gear pump (not shown) in Fig. 1). The resulting product in divided form is then cooled, preferably to room temperature, for example, by directing it to a cooling device (not shown in Fig. 1).

FIG. 2 shows an additional embodiment of the apparatus (200) for producing an elastomeric compound according to the present invention: the same reference numbers have the same values as shown in FIG. 1. It is believed that all alternatives disclosed above with reference to FIG. 1 are also valid with reference to FIG. 2.

According to this embodiment, the second elastomeric compound (108) is sent to an additional internal mixer (201) (for example, a Banbury ^® mixer). Feeding to said additional internal mixer (201) can be particularly useful when not all components of the elastomeric compound are supplied to the internal mixer (101). In this case, for example, vulcanizing agents and / or activators and / or accelerators can be supplied to said additional internal mixer (201).

According to a particular embodiment in FIG. 2, the second elastomeric compound (108) is cooled, preferably to room temperature, by passing it through a cooling device (109), before being fed to said additional internal mixer (201).

Alternatively, the second elastomeric compound (108) can be sent directly, without cooling, to said additional internal mixer (201) (not shown in FIG. 2).

Alternatively, the second elastomeric compound (108) can be obtained in the form of a parted product, as described above, and then fed to said additional internal mixer (201) (not shown in FIG. 2).

FIG. 3 shows an additional embodiment of the apparatus (300) for producing an elastomeric compound according to the present invention: the same reference numbers have the same values as shown in FIG. 1. It is believed that all alternatives disclosed above with reference to FIG. 1 are also valid with reference to FIG. 3.

In the specific embodiment of FIG. 3 shows a mixing device (101a), including an internal mixer (101) and a conveying extruder (301).

According to this embodiment, the first elastomeric compound (104) is fed into a conveying extruder (301) (for example, an extruder with one spiral screw) through a feed funnel (302).

The feed to said transporting extruder (301) may provide the ability to control the feed rate of said first elastomeric compound (104) to said mixing extruder (106).

According to a particular embodiment, in FIG. 3, the first elastomeric compound (104) is sent directly to the conveying extruder (301).

According to a particular embodiment, in FIG. 3, the first elastomeric compound (104) from said transporting extruder (301) is sent directly to the mixing extruder (106), through a feed funnel (105), for example, in the form of a continuous tape, forcing it through a roll head (303), for example, using gear pump (not shown in Fig. 3).

Alternatively, said transporting extruder (301), instead of said roll head (303), can be equipped with:

- an extrusion head equipped with a perforated spinneret plate equipped with knives in order to obtain said first elastomeric compound in the form of a product divided into parts, before feeding it to said mixing extruder (106) (not shown in Fig. 3); or

an open head to allow said first elastomeric compound to flow directly into said mixing extruder (106) (not shown in FIG. 3).

Alternatively, said conveying extruder (301) may be replaced with an open type mixer with runners (not shown in FIG. 3).

Alternatively, an open type mixer with runners may be placed between said internal mixer (101) and said conveying extruder (301) (not shown in FIG. 3).

FIG. 4 shows an additional embodiment of the apparatus (400) for producing an elastomeric compound according to the present invention: the same reference numbers have the same meanings as shown in FIG. 1 and FIG. 3. It is believed that all alternatives disclosed above with reference to FIG. 1 as well as in FIG. 3 are also valid with reference to FIG. four.

According to a particular embodiment, in FIG. 4, the first elastomeric compound (104) at the outlet of the conveying extruder (301) is first cooled, preferably to room temperature, by passing it through a cooling device (401), before being fed into the mixing extruder (106). Said cooling may be useful in order to increase the viscosity of said first elastomeric compound before feeding it to said mixing extruder (106), thereby allowing better mixing of said first elastomeric composition in said mixing extruder (106).

Alternatively, the first elastomeric compound (104) at the exit of the conveying extruder (301), after cooling by passing it through a cooling device (401), can be obtained in the form of a product divided into parts using a cutting device (for example, a crusher equipped with rotating blades) before feeding into the mixing extruder (106) (not shown in FIG. 4). In this case, it is preferable that the feed to the mixing extruder (106) can be controlled using feeders (for example, volumetric dispensers or feeders for weight loss in the hopper) (not shown in Fig. 4).

FIG. 5 shows an additional embodiment of the apparatus (500) for producing an elastomeric compound according to the present invention: the same reference numbers have the same values as shown in FIG. 1, FIG. 3 and in FIG. 4. It is believed that all alternatives disclosed above with reference to FIG. 1, FIG. 3, and also in FIG. 4 are also valid with reference to FIG. 5.

According to a particular embodiment, in FIG. 5, a second elastomeric compound (108) is supplied to an additional internal mixer (501) (e.g., a Banbury ^® mixer). Feeding to said additional internal mixer (501) can be particularly useful when not all components of the elastomeric compound are supplied to the internal mixer (101). In this case, for example, vulcanizing agents and / or activators and / or accelerators can be supplied to said additional internal mixer (501).

According to a particular embodiment, in FIG. 5, the second elastomeric compound (108) is cooled, preferably to room temperature, by passing it through a cooling device (109), before feeding it to said additional internal mixer (501). Said cooling may be useful in order to increase the viscosity of said second elastomeric compound before feeding it to said additional internal mixer (501), thereby enabling better mixing of said second elastomeric composition in said additional internal mixer (501).

Alternatively, the second elastomeric compound (108) can be directly directed, without cooling, to said additional internal mixer (501) (not shown in FIG. 5).

Alternatively, the second elastomeric compound (108) can be obtained in the form of a divided product, as described above, and then fed to the specified additional internal mixer (501).

FIG. 6 shows an additional embodiment of a plant (600) for producing an elastomeric compound according to the present invention: the same reference numbers have the same values as shown in FIG. 1. It is believed that all alternatives disclosed above with reference to FIG. 1 are also valid with reference to FIG. 6.

According to a particular embodiment, in FIG. 6, the second elastomeric compound (108) is fed directly to the extruder (601) for the manufacture of a semi-finished product (for example, a single-screw hot feed extruder with a short cylinder) through a feed funnel (602).

The second elastomeric compound is withdrawn from the extruder (601) in the form of a sheet (603) (for example, in the form of a semi-finished product applicable in the manufacture of a tire) by injection through an extrusion die (not shown in Fig. 6).

Alternatively, the second elastomeric compound (108) is withdrawn from the extruder (601) in the form of a sheet (603) (for example, in the form of a semifinished product applicable in the manufacture of a tire) by injection through a roll head (not shown in FIG. 6).

Typically, the resulting sheet (603) (for example, in the form of a semifinished product useful in the manufacture of a tire) is then subjected to a cooling treatment, usually with water and / or compressed air. The sheet (603) thus treated is then usually placed on stands or on reels in anticipation of further processing.

Alternatively, a continuous elongated ribbon-like element (not shown in FIG. 6) can be obtained from the extruder (601), which can be used directly, without storage, to make the tire in operations as described above.

FIG. 7 shows an additional embodiment of the apparatus (700) for producing an elastomeric compound according to the present invention: the same reference numbers have the same values as shown in FIG. 1 and FIG. 6. It is believed that all alternatives disclosed above with reference to FIG. 1, and also with reference to FIG. 6 are also valid with reference to FIG. 7.

According to a particular embodiment, in FIG. 7, the second elastomeric compound (108) is cooled, preferably to room temperature, by passing through a cooling device (109), before being fed into an extruder (601a) (for example, a single-screw cold feed extruder with a long cylinder), through a feed funnel (602).

The second elastomeric compound (108) is withdrawn from the extruder (601a) in the form of a sheet (603) (for example, in the form of a semifinished product applicable in the manufacture of a tire) by injection through an extrusion die (not shown in Fig. 7).

FIG. 8 shows an additional embodiment of the apparatus (800) for producing an elastomeric compound according to the present invention: the same reference numbers have the same meanings as shown in FIG. 1 and FIG. 6. It is believed that all alternatives disclosed above with reference to FIG. 1, and also with reference to FIG. 6 are also valid with reference to FIG. 8.

According to a particular embodiment, in FIG. 8, the second elastomeric compound is directly removed from the mixing extruder (106) (for example, in the form of a semi-finished product applicable in the manufacture of a tire) by forcing it through a roll head (107).

Alternatively, the second elastomeric compound (108) is withdrawn from the mixing extruder (106) in the form of a sheet (603) (for example, in the form of a semi-finished product useful in the manufacture of a tire) by injection through an extrusion die (not shown in FIG. 8).

FIG. 9a is a side view of two screws (900) of a self-cleaning twin screw extruder with unidirectional interlocking screws.

FIG. 9b is a cross-sectional view of the screws (901) of a self-cleaning twin screw extruder with unidirectional interlocking screws according to the present invention.

The present invention will now be illustrated with a number of production examples, which are provided for illustrative purposes only and without any limitation of the present invention.

EXAMPLES 1-3

Obtaining Elastomeric Compounds

The formulation of the obtained elastomeric compounds is shown in Table 1 (the amounts of various components are given in phr (parts per hundred parts of the compound)).

TABLE 1 Component phr S-sbr 90 BR 35 Silica 70 X50S ^® 11,2 Zinc oxide 2.5 Stearic acid 2.0 Paraffin 1,0 Aromatic oil 8.0 Antioxidant 2.0 Sulfur 1,2 DPG80 2.0 Cbs 2.0

S-SBR: obtained by polymerization in a solution of styrene / 1,3-butadiene copolymer having a styrene content of 25% by weight and a vinyl group content of 50% by weight, relative to the total weight of the copolymer; and containing 37.5 phr of aromatic oil (Buna ^® VSL 5025-1 - Lanxess);

BR: polybutadiene (Europrene Neocis ^® BR40 - Polimeri Europa);

Silica: Zeosil ^® 1165 MP (Rhodia);

X50S ^® : silane cross-linking reagent, comprising 50% by weight of carbon black and 50% by weight of bis (3-triethoxysilylpropyl) tetrasulfide (Degussa-Hüls);

Antioxidant: phenyl-para-phenylenediamine (6-PPD - Akzo Nobel);

DPG80 (accelerator): diphenylguanidine (Rhenogran ^® DPG80 - Rhein Chemie);

CBS (accelerator): N-cyclohexyl-2-benzothiazolylsulfenamide (Vulkacit ^® CZ / C, Lanxess).

The above elastomeric compounds were prepared as follows.

Example 1 (comparative)

1st stage

All components listed in Table 1, except sulfur and accelerators (DPG80 and CBS) were mixed together in a mixer Banbury ^® (model F270), acting under the following operating conditions:

- feed: 225 kg;

- temperature: 30 ° C;

- mixing time: 240 seconds;

- fill factor: 68%;

- rotor rotation speed: 50 rpm;

- temperature at unloading: 150 ° C.

2nd stage

The elastomeric compound obtained in the 1st stage was cooled to room temperature (23 ° C) and then fed into the same Banbury ^® mixer as described above, and further mixing was carried out in operation under the following operating conditions:

- feed: 215 kg;

- temperature: 30 ° C;

- mixing time: 195 seconds;

- fill factor: 66%;

- rotor rotation speed: 40 rpm;

- temperature at unloading: 140 ° C.

3rd stage

The elastomeric compound obtained in the 2nd stage, cooled to room temperature (23 ° C), as well as sulfur and accelerators (DPG80 and CBS) were fed into the same Banbury ^® mixer as described above, and further mixing was carried out in the following steps operational conditions:

- feed: 225 kg;

- temperature: 30 ° C;

- mixing time: 195 seconds;

- fill factor: 66%;

- rotor rotation speed: 40 rpm;

- temperature at unloading: 110 ° С.

The elastomeric compound withdrawn from the Banbury ^® mixer was then cooled to room temperature (23 ° C).

The obtained elastomeric compound was tested to evaluate the following properties: Mooney viscosity (ML 1 + 4), mechanical properties (both static and dynamic), as well as the dispersion of the filler: the results are shown in Table 2.

Example 2 (according to the invention)

An elastomeric compound was obtained using the apparatus of FIG. four.

For this purpose, the elastomeric compound obtained according to Example 1 was fed directly (without cooling) to a conveying extruder (i.e., a single screw extruder) operating under the following operating conditions:

- feed rate: 4100 kg / h;

- screw rotation speed: 20 rpm;

- temperature profile: 30 ° C;

- temperature of the elastomeric compound, measured at the exit of the extruder: 110 ° C.

The elastomeric compound removed from the conveying extruder was cooled to room temperature (23 ° C) and then sent to a self-cleaning twin screw extruder with unidirectional interlocking augers Maris TM92HT having a nominal screw diameter of 92 mm and an L / D ratio (“length / diameter”) 32 operating under the following operating conditions:

- feed rate: 250 kg / h;

- rotation speed of two screws: 70 rpm;

- torque: 63%;

- temperature profile: 40-50-60-50-40-30-30-20-20 ° C;

- temperature of the elastomeric compound, measured at the exit of the extruder: 120 ° C.

The elastomeric compound withdrawn from a self-cleaning twin-screw extruder with unidirectional interlocking screws is then cooled to room temperature (23 ° C).

The obtained elastomeric compound was tested to evaluate the following properties: Mooney viscosity (ML 1 + 4), mechanical properties (both static and dynamic), as well as the dispersion of the filler: the results are shown in Table 2.

Example 3 (according to the invention)

An elastomeric compound was obtained using the apparatus of FIG. 5.

For this purpose, all the components listed in Table 1, with the exception of sulfur and accelerators (DPG80 and CBS), were mixed together in a Banbury ^® mixer (model F270), operating under the following operating conditions:

- feed: 225 kg;

- temperature: 30 ° C;

- mixing time: 240 seconds;

- fill factor: 68%;

- rotor rotation speed: 50 rpm;

- temperature at unloading: 150 ° C.

For this purpose, the elastomeric compound withdrawn from the Banbury ^® mixer was fed directly (without cooling) to a conveying extruder (i.e. a single screw extruder) operating under the following operating conditions:

- feed rate: 3400 kg / h;

- screw rotation speed: 17 rpm;

- temperature profile: 30 ° C;

- temperature of the elastomeric compound, measured at the exit of the extruder: 145 ° C.

The elastomeric compound removed from the conveying extruder was cooled to room temperature (23 ° C) and then sent to a self-cleaning twin screw extruder with unidirectional interlocking augers Maris TM92HT having a nominal screw diameter of 92 mm and an L / D ratio (“length / diameter”) 32 operating under the following operating conditions:

- feed rate: 200 kg / hour;

- rotation speed of two screws: 60 rpm;

- torque: 80%;

- temperature profile: 40-50-60-50-40-30-30-20-20 ° C;

- temperature of the elastomeric compound, measured at the exit of the extruder: 130 ° C.

The elastomeric compound withdrawn from a self-cleaning twin-screw extruder with unidirectional interlocking screws was cooled to room temperature (23 ° C) and then fed to an additional Banbury ^® mixer, to which sulfur and accelerators (DPG80 and CBS) were added, operating under the following operating conditions:

- feed: 225 kg;

- temperature: 30 ° C;

- mixing time: 195 seconds;

- fill factor: 68%;

- rotor rotation speed: 50 rpm;

- temperature at unloading: 110 ° С.

The elastomeric compound withdrawn from the optional Banbury ^® mixer was then cooled to room temperature (23 ° C).

The obtained elastomeric compound was tested to evaluate the following properties: Mooney viscosity (ML 1 + 4), mechanical properties (both static and dynamic), as well as the dispersion of the filler: the results are shown in Table 2.

Mooney Viscosity

Mooney viscosity ML (1 + 4) at a temperature of 100 ° C was measured according to ISO 289-1: 1994 on non-crosslinked elastomeric compounds obtained as described above.

Mechanical properties

The modulus of elasticity (Modulus at 100% elongation and Modulus at 300% elongation), breaking stress at break, and elongation at break were measured according to ISO 37: 2005 on samples of the aforementioned elastomeric compounds vulcanized at a temperature of 170 ° C in within 10 minutes The results are shown in Table 2.

Hardness in units of IRHD (international hardness units) (at a temperature of 23 ° C) according to ISO 48: 1994 was measured on samples of the aforementioned elastomeric compounds vulcanized at a temperature of 170 ° C for 10 min. The results are shown in Table 2.

Table 2 also shows the dynamic mechanical properties measured using an Instron dynamic clutch-compression device according to the following methods. A test sample of crosslinked elastomeric compounds (vulcanized at a temperature of 170 ° C for 10 min), having a cylindrical shape (length = 25 mm; diameter = 12 mm), pre-loaded to compress to 7.5% longitudinal strain relative to the original length and maintained at a predetermined temperature (23 ° C and 70 ° C) throughout the test, was subjected to dynamic sinusoidal loading having an amplitude of ± 3.5% relative to the length at preload, with a frequency of 10 Hz. Dynamic mechanical properties were expressed in terms of the values of the dynamic elastic modulus (E ') and the delta tangent (loss coefficient). The tangent delta value was calculated as the ratio between the viscosity modulus (E ”) and the elastic modulus (E ').

Filler Dispersion

The dispersion of the filler (i.e., the dispersion of silica) was measured according to ISO 11345: 2006.

For this purpose, a test sample of crosslinked elastomeric compounds (vulcanized at 170 ° C for 10 min), having the following dimensions: 4 mm × 4 mm, was used to evaluate both the dispersion of silicon oxide (X value) and the distribution of silicon oxide (value Y) using a DisperGrader Model 1000NT with a 100x magnification (TECH PRO Corp.). This model has several scales suitable for comparison. The scale that was selected for this test was the RCB scale. This scale is usually used to measure elastomeric compounds containing carbon black as a reinforcing filler.

To determine the dispersion of silicon oxide (X values), ten reference images were used. Using these reference images, an algorithm was derived and then applied to an unknown sample. DisperGrader then analyzes the unknown sample and automatically assigns the degree of dispersion (X value) for the unknown sample. Higher dispersion values (X values) represent better dispersion. A visual comparison is demonstrated on a computer monitor. An unknown sample is shown on one half of the screen, and the control image is simultaneously displayed next to it. The numerical value of the degree of dispersion (X value) is shown on the screen and submitted to a separate computer for further analysis.

The Y value is not based on a visual comparison of photographic standards, but based on the actual size and number of large agglomerates. High scores mean that there are no agglomerates present in the test areas that have an average diameter higher than 23 microns.

TABLE 2 Example one(*) 2 3 Mooney Viscosity (ML 1 + 4) 77 76 78 Static mechanical properties Modulus at 100% elongation (CA1) (MPa) 3.04 2.97 2.88 Modulus at 300% elongation (CA2) (MPa) 11.9 12.32 12.73 SAZ / CA1 3.91 4.15 4.42 Breaking stress at break (MPa) 14.04 15.88 15,57 Elongation at break (%) 376 402 383 Hardness in units of IRHD (at a temperature of 23 ° C) 77 77 77 Dynamic mechanical properties E '(23 ° C) 9.62 10.46 10.38 E '(70 ° C) 7.62 8.11 8.07 Tangent delta (23 ° C) 0.258 0.256 0.254 Tangent delta (70 ° C) 0.119 0,120 0.116 Silica dispersion X value 3.8 4.9 4.1 Y value 7.7 9.1 8.8 (*): comparative

The data shown in Table 2 above show that the crosslinked elastomeric compounds obtained according to the present invention (Examples 2 and 3) have improved tensile strength at break, while the remaining properties do not show any deterioration relative to the crosslinked elastomeric compound obtained according to the prototype (Example one).

Moreover, the data shown in Table 2 above show that the crosslinked elastomeric compounds obtained according to the present invention (Examples 2 and 3) have improved dispersion of silicon oxide relative to the crosslinked elastomeric compound obtained according to the prototype (Example 1).

EXAMPLES 4-5

Obtaining Elastomeric Compounds

The formulation of the obtained elastomeric compounds is shown in Table 3 (the amounts of various components are given in phr (parts per hundred parts of the compound)).

TABLE 3 Compound phr Nr 70 BR thirty N326 55 Zinc oxide 5,0 Stearic acid 2.0 Antioxidant 2.0 Resorcinol 1,0 Hmmm 2.0 Sulfur 5.5 PVI 0.1 DCBS 1,0

NR: natural rubber (STR20 - Taiteck Rubber);

BR: polybutadiene (Europrene Neocis ^® BR40 - Polimeri Europa);

N326: carbon black;

Antioxidant: phenyl-para-phenylenediamine (6-PPD - Akzo Nobel);

HMMM: hexamethoxymethylmelamine;

PVI (retarder): N-cyclohexylthiophthalimide (Santogard ^® PVI - Flexys);

DCBS (accelerator): benzothiazolyl-2-dicyclohexyl sulfenamide (Vulkacit ^® DZ / EGC - Lanxess).

The above elastomeric compounds were prepared as follows.

Example 4 (comparative)

1st stage

All components listed in Table 3, with the exception of sulfur, a moderator (PVI), hexamethoxymethylmelamine (HMMM) and accelerator (DCBS), were mixed together in a Banbury ^® mixer (model F270), operating under the following operating conditions:

- feed: 225 kg;

- temperature: 30 ° C;

- mixing time: 200 seconds;

- fill factor: 73%;

- rotor rotation speed: 40 rpm;

- temperature at unloading: 155 ° C.

2nd stage

The elastomeric compound obtained in the 1st stage was cooled to room temperature (23 ° C) and then fed into the same Banbury ^® mixer as described above, and further mixing was carried out in operation under the following operating conditions:

- feed: 200 kg;

- temperature: 30 ° C;

- mixing time: 130 seconds;

- fill factor: 65%;

- rotor rotation speed: 40 rpm;

- temperature at unloading: 105 ° C.

The resulting elastomeric compound was then cooled to room temperature (23 ° C).

The obtained elastomeric compound was tested to evaluate the following properties: Mooney viscosity (ML 1 + 4), mechanical properties (both static and dynamic), and also the dispersion of the filler: the results are shown in Table 4.

Example 5 (according to the invention)

An elastomeric compound was obtained using the apparatus of FIG. four.

For this purpose, the elastomeric compound obtained according to Example 4 was fed directly (without cooling) to a conveying extruder (i.e., a single screw extruder) operating under the following operating conditions:

- feed rate: 5500 kg / h;

- screw rotation speed: 25 rpm;

- temperature profile: 25 ° C;

- temperature of the elastomeric compound, measured at the exit of the extruder: 105 ° C.

The elastomeric compound removed from the conveying extruder was cooled to room temperature (23 ° C) and then sent to a self-cleaning twin screw extruder with unidirectional interlocking augers Maris TM92HT having a nominal screw diameter of 92 mm and an L / D ratio (“length / diameter”) 32 operating under the following operating conditions:

- feed rate: 250 kg / h;

- rotation speed of two screws: 60 rpm;

- torque: 75%;

- temperature profile: 40-80-90-80-40-30-30-30-30 ° С;

- temperature of the elastomeric compound, measured at the exit of the extruder: 100 ° C.

The elastomeric compound withdrawn from a self-cleaning twin-screw extruder with unidirectional interlocking screws is then cooled to room temperature (23 ° C).

The obtained elastomeric compound was tested to evaluate the following properties: Mooney viscosity (ML 1 + 4), mechanical properties (both static and dynamic), and also the dispersion of the filler: the results are shown in Table 4.

Mooney viscosity ML (1 + 4), mechanical properties, as well as dispersion of the filler (i.e. carbon black), were measured as reported above.

TABLE 4 Example four(') 5 Mooney Viscosity (ML 1 + 4) 59.6 57.3 Static mechanical properties Modulus at 100% elongation (CA1) (MPa) 4.27 4.09 Breaking stress at break (MPa) 15.25 17.65 Elongation at break (%) 321 346 Hardness in units of IRHD (at a temperature of 23 ° C) 83.0 83.6 Dynamic mechanical properties E '(23 ° C) 14.92 14.64 E '(70 ° C) 10.39 10.31 Tangent delta (23 ° C) 0.190 0.186 Tangent delta (70 ° C) 0.138 0.135 Carbon black dispersion X value <0.5 3.0 Y value 2,4 8.2 (*): comparative

The data shown in Table 4 above show that the crosslinked elastomeric compounds obtained according to the present invention (Example 5) have an improved value of breaking stress at break, while the remaining properties do not show deterioration relative to the crosslinked elastomeric compound obtained according to the prototype (Example 4) .

Moreover, the data shown in Table 4 above show that the crosslinked elastomeric compound obtained according to the present invention (Example 5) has a significantly improved dispersion of carbon black relative to the crosslinked elastomeric compound obtained according to the prototype (Example 4).

Claims (18)

1. A method of obtaining a tire, including:
the manufacture of assembled, but not vulcanized tires, including many structural elements;
subjecting the assembled but not vulcanized tire to molding and stitching to form a finished tire;
in which at least one of these structural elements includes an elastomeric compound obtained:
supplying at least one elastomeric polymer (102) selected from a diene elastomeric polymer and a monoolefin elastomeric polymer or a mixture thereof, and at least one reinforcing filler (103) and vulcanizing agents in at least one batch mixing device (101) of a mixing device (101a), wherein said at least one batch mixing device (101) has two opposite-rotation screws, and mixing in said at least one mixing device The periodic batch (101) is carried out at a rotor speed of about 20 rpm to about 60 rpm;
mixing and dispersing in said at least one mixing device (101a) of said at least one reinforcing filler (103) in said at least one elastomeric polymer (102) to obtain an elastomeric compound (104, 108);
withdrawing said elastomeric compound (104, 108) from said at least one mixing device (101a);
feeding said elastomeric compound (104, 108) into at least one continuous mixing device (106), said continuous mixing device comprising at least two rotating screws;
mixing said elastomeric compound (104, 108) in said at least one continuous mixing device (106);
removing said elastomeric compound (104, 108) from said at least one continuous mixing device (106). 2. A method for producing a tire according to claim 1, wherein the preparation of the elastomeric compound (104, 108) is carried out in a continuous or batch mode. 3. The method for producing a tire according to claim 1 or 2, wherein said batch mixing device is selected from a closed mixer or open type mixers. 4. A method for producing a tire according to claim 1, wherein mixing in said at least one batch mixing device (101) is carried out using a filling factor of the mixing chamber of not higher than about 80%. 5. A method for producing a tire according to claim 1, wherein said at least one continuous mixing device (106) has at least two unidirectional screws. 6. The method for producing a tire according to claim 5, wherein said at least two unidirectional screws are at least partially interlocked. 7. The method of manufacturing a tire according to claim 5, wherein said at least two unidirectional screws are substantially completely interlocked. 8. A method for producing a tire according to claim 1, wherein said continuous mixing device (106) is a mixing extruder. 9. A method of producing a tire according to claim 8, wherein said mixing extruder (106) includes:
a housing, said housing comprising at least one inlet and an outlet;
wherein said at least two rotary screws are rotatably mounted in said housing. 10. The method of producing a tire according to claim 8 or 9, wherein said mixing extruder is selected from: twin-screw extruders with unidirectional rotation; unidirectional multi-screw extruders comprising more than two screws, such as, for example, ring extruders; roll planetary extruders. 11. The method of producing a tire according to claim 1, in which the mixing in the at least one continuous mixing device is carried out at a screw rotation speed of from about 10 rpm to about 600 rpm. 12. The method for producing a tire according to claim 1, wherein said method comprises cooling said elastomeric compound (104, 108) before feeding it to said at least one continuous mixing device (106). 13. The method of producing a tire according to claim 12, wherein said first elastomeric compound is cooled to a temperature of from about 15 ° C to about 40 ° C. 14. The method for producing a tire according to claim 1, wherein said mixing device comprises at least one conveying extruder and an elastomeric compound (104, 108) is fed to said at least one conveying extruder before being fed to said at least one mixing device continuous operation (106). 15. A method of manufacturing a tire according to claim 1, wherein said mixing device comprises at least one indoor mixer (101) and at least one open type mixer, said open type mixer being located downstream of said at least one closed mixer mixer (101). 16. A method for producing a tire according to claim 1, wherein said at least one continuous mixing device (106) is located upstream of the device for manufacturing a semi-finished product using said second elastomeric compound (104, 108). 17. A method for producing a tire according to claim 1, wherein said at least one continuous mixing device is equipped with (106) a roll head (107). 18. A method for producing a tire according to claim 1, wherein said at least one continuous mixing device (106) is equipped with an extrusion head.

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