MXPA99008382A - Tires with floor components and / or side wall reinforced with sil - Google Patents

Abstract

The present invention relates to the preparation of rubber compositions for applications in rim floor and rim sidewalls. A rim is provided having an elaborate floor of said composition designed for relatively heavy loads such as, for example, truck tires. A rim having a sidewall of such a composition is also provided. Said rim component rubber compositions are of rubber compositions reinforced with precipitated silica and carbon black selected in specified amounts and prepared in a prescribed order of addition to the rubber composition and composed of elastomers as a specific composition of natural rubber or rubber. synthetic cis-1,4 cis polybutylene rubber with cis 1,4-polybutadiene rubber or with a combination of cis 1,4-polybutadiene rubber and 1,4-polybutadiene rubber

Description

TIRES WITH FLOOR REINFORCED FLOOR AND / OR SIDE WALL COMPONENTS FIELD OF THE INVENTION This invention relates to rubber compositions for applications in floor components and rim sidewalls prepared by the sequential addition of precipitated silica and carbon blacks specified to the rubber composition. In one aspect, the tire floor is designed to be used under relatively heavy loads, such as truck tires. Said rim component rubber compositions are rubber compositions reinforced with precipitated silica and specified carbon black and composed of specified elastomers. BACKGROUND OF THE INVENTION [0002] Rubber compositions for tire floors for use with heavy loads, for example, truck tires, can be reinforced with precipitated silica and carbon black and can be composed of several elastomers. However, for such rims, special considerations should usually be made as to the compositions of the tire floor rubber. For example, passenger tire floors are normally employed with a desired balance between a relatively low rolling resistance for fuel economy and limited floor wear and relatively high traction for road surface control. However, truck tire floors are normally designed for use with relatively heavy loads and the traction quality of the rubber composition is usually not as significant since the higher loads placed on the rim itself add to the traction of the floor. of the rim on the surface of the road. Also, significantly, said truck tire floors are usually desirable composed of rubber compositions designed to have a lesser accumulation of internal heat to reduce the bearing temperature of the tire floor. Said rubber compositions frequently exhibit less traction between the floor and the road surface, depending more on the load applied on the rim to improve the traction characteristic of the floor. Therefore, in the case of truck tire floors, special attention should be given to the selection of rubber reinforcement, including selection of carbon black reinforcement, as well as the selection of elastomers to be used with the reinforcement specified for the reduction of the quality of heat accumulation normally desired. It is recognized that various materials, and quantities of the various individual materials for tire floors, such as, for example, precipitated silica, selected carbon black reinforcement, rubber processing oils, as well as individual elastomers including natural rubber, rubber, are known to be employed. of 1, 4-polybutadiene cis and rubber of 1,4-polybutadiene trans. However, in the case of truck tire floors, designed to effectively load significant weights, it is considered here that the selection of materials is more specific in terms of materials as well as more specific in terms of combination of materials. In another aspect of the invention, rims with side walls of a specified rubber composition prepared in a prescribed order of addition of carbon black and precipitated silica are also provided. In the case of rim sidewalls as well as rim floor, it is recognized that the cis 1,4-polybutadiene rubber has been suggested for use in rubber compositions. However, it is believed that it is generally known that the use of relatively high amounts of cis 1,4-polybutadiene rubber in rubber compositions also containing a relatively high concentration of carbon black reinforcement usually results in an undesirably low strength of the rubber. Wear (floor resistance). The wear resistance of a rubber composition is usually a very important rubber property both in the case of rim floors and in the case of rim sidewalls. Exemplary suggestions for the use of 1, 4-polybutadiene trans in various rubber compositions for various rim components, including rim floor, are found for example in U.S. Patent Nos. 5,174,838 and 5,386,865. It will be noted that certain forms of 1,4-polybutadiene trans are elastomeric in nature and some forms, usually dependent on a certain form of their microstructure, in fact have at least one melting point and, therefore, are more similar to a thermoplastic resin in its unvulcanized state and before mixing with elastomers. Therefore, they are sometimes known in their unvulcanized state as a "1,4-polybutadiene trans" resin. When mixed and subjected to vulcanization with sulfur with various elastomers vulcanizable with sulfur, such 1,4-polybutadiene trans resins apparently become elastomeric in nature. This invention focuses primarily on the discovery for rim floors and rim sidewalls, the use of specific combinations in terms of known natural rubber or synthetic natural rubber, together with selected butadiene-based elastomer (s). in combination with specific particle reinforcements and processing oil in specified quantities, where precipitated silica and carbon black are required in a prescribed order of addition. It is believed that the described preparation of said specific combinations for materials, which specify defined quantities of such materials, is novel and inventive, especially for such truck tire floors. The rubber composition itself, which depends to a large extent on the selection of carbon black, can also be useful as a rim sidewall or other rim components or in rubber bands, conveyor belts or other industrial product applications. . In the description of this invention, the terms "rubber" and "elastomer", if used herein, may be used interchangeably, unless otherwise indicated. The terms "rubber composition", "composite rubber" and "rubber compound", if used herein, are used interchangeably to refer to "rubber that has been mixed with various material ingredients" and such terms are well known to part of the experts in the field. In the description of this invention, the term "phr" if used herein, and in accordance with conventional practice, refers to "parts of a respective material per 100 parts by weight of rubber, or elastomer", which, in this invention , are intended to include the aforementioned trans 1,4-polybutadiene resin. A reference to an elastomer Tg refers to a "glass transition temperature" which can be conveniently determined by a differential scanning calorimeter at a heating rate of 10 ° C per minute. A melting point of polymer, especially the uncured resin polymer of 1,4-polybutadiene trans, can be conveniently determined by the use of a differential scanning calorimeter at a heating rate of about 10 ° C per minute. Said method of determining melting point is well known to those skilled in the art. A preparation of a 1,4-polybutadiene trans resin and its characterization can be easily found in U.S. Patent No. 5,089,574. COMPENDIUM AND PRACTICE OF THE INVENTION In accordance with this invention, there is provided a method of preparing a rubber composition comprising, based on 100 parts by weight (phr) of diene-based elastomers, (A) the mixture of (1) ) about 20 to about 60 phr of cis 1,4-polyisoprene elastomer having a glass transition temperature within a range of about -65 ° C to about 75 ° C and (2) about 40 to about 80 phr of (a) a 1, 4-polybutadiene trans rubber having a glass transition temperature within a range of about -70 ° C to about -80 ° C and rubber of 1, Cis-4-polybutadiene having a glass transition temperature within a range of about -100 ° C to about -110 ° C in a weight ratio between 1,4-polybutadiene trans and 1,4-polyisoprene cis within from a range of about 3/1 to about 1/3 or (b) cis 1,4-polybutadiene rubber having a glass transition temperature within a range of about -100 ° C to about -110 ° C , (B) of approximately 40 approximately 80 phr of carbon black and reinforcing filler. precipitated silica comprising from about 20 to about 80 phr of precipitated silica and from about 15 to about 60 phr of carbon black and (C) at least one silica coupling agent having a reactive portion with silanol groups on the surface of said silica and an additional interactive portion with said elastomers and (D) from zero to about 10, alternatively from about 5 to about 10 phr of rubber processing oil; wherein said carbon black is selected from a first carbon black having a DBP value within a range of about 100 to about 150 cc / 100 gm and an Iodine index within a range of about 90 to about 150 g / kg or a second carbon black having a DBP value within a range of about 65 to about 130 cc / 100 gm and an Iodine index within a range of about 25 to about 85 g / kg; Wherein said method comprises (1) the mixture of said elastomers and carbon black, excluding silica and sulfur curing agent, in an internal rubber mixer in a first mixing stage of internal rubber preparation for a period of about 1 to about 10 minutes at a temperature within a range of about 150 ° C to about 180 ° C; (2) the mixture of said precipitated silica and silica coupling agent, excluding carbon black and sulfur curing agent, in at least one internal rubber mixer in an internal rubber mixing stage of subsequent, additional preparation, during a period of from about 1 to about 10 minutes at a temperature from about 100 ° C to about 180 ° C; wherein said oil, if employed, can be added either with the carbon black and / or with the silica, (3) the mixture of silica with curing agent (s) in an internal rubber mixer in a mixing stage of final inner rubber for a period of about 1 to about 4 minutes at a temperature within a range of about 80 ° C to about 130 ° C; wherein said rubber composition is removed from said internal rubber mixer at the end of each mixing step and is cooled to a temperature below 40 ° C. In accordance with the present invention, a rubber composition prepared by such a method is provided. In accordance with the present invention, said rubber composition is provided as a rubber composition vulcanized with sulfur. In accordance with the present invention. A rubber composition prepared by the method of the present invention is provided wherein said carbon black is said first carbon black and, further, a rim having a floor made with said rubber composition is provided. According to the present invention, the rubber composition prepared by the method of this invention is provided wherein said carbon black is said second black smoke and, furthermore, a rim having at least some components of its sidewall as said rubber composition. Accordingly, in one aspect of the invention a rubber composition is prepared in a sequential series of at least two separate and individual steps of internal preparation rubber blended, or stages, wherein the diene-based elastomer is first mixed with the prescribed carbon black, and then the silica is added in a subsequent separate mixing step and then a final mixing step is carried out in which the curing agents are mixed at a lower temperature and for a period of time substantially less. This sequential mixing, which requires the addition of carbon black and silica in a separate mixing step, can sometimes be referred to herein as "cascade mixing". Thus, said state method is distinguished in a simple sequential addition of ingredients in a mixing process employing only one preparation mixing step followed by a final mixing step for an addition of curing agents. It is required after each mixing step that the rubber mixture is actually removed from the rubber mixer and cooled to a temperature within a range of about 50 ° C to about 20 ° C, and then added back to a mixer. internal rubber for the next step of sequential mixing, or stage. In practice, the preferred weight ratio between the silica and the carbon black for the rubber compositions is 1/1 approximately 3/1. It is an important aspect of the invention that, for the preparation of the rubber composition, the carbon black and the elastomers are mixed in the absence of silica and silica coupler after which in a subsequent separate mixing step the silica and the Silica coupler are mixed with the elastomer / black blend.

By using such a method, it has been observed that, compared to the mixing of the elastomer, carbon black, silica and silica coupler in the same mixing step, the white properties selected for the rubber compositions of this patent application are best met. Another important aspect of the invention is the selection of the smoke black in combination with the aforementioned sequential mixing method. Particularly, for this invention the first carbon black (a) is required for a tire floor composition and a second carbon black (b) is required for a rubber outer sidewall rim composition. Particularly, for this invention, carbon black (a) is used for a tire floor rubber composition because it promotes a relatively high modulus and good abrasion resistance for the rubber composition. Thus, the selection of carbon black depends on the intended use of the rubber composition. A further significant aspect of the present invention is the specific use for materials of a prescribed combination of known diene-based elastomers, such as particularly cis 1,4-polyisoprene rubber (natural or synthetic, natural rubber being preferred) in combination either with 1, 4-polybutadiene trans rubber and cis 1,4-polybutadiene rubber, in the tire floor rubber composition in a circumstance in which the tire floor rubber is reinforced with precipitated silica with a defined amount of specified carbon black reinforcement and a minimum amount of rubber processing oil, i.e. a maximum of about 10 phr, and preferably 0 phr of rubber processing oil. The restriction regarding the rubber processing oil is considered important here because levels (amounts) + processing oil elevator are considered here as negative in terms of the desired wear, modulus and abrasion resistance properties of the rubber composition - which are desirable properties for a rubber composition for rim floor or for external rim side wall. The use of cis 1,4-polyisoprene elastomer, particularly natural rubber, with a relatively low glass transition temperature within a range of about -65 ° C to about -75 ° C is considered here as important and beneficial for the rim floor as a potential phase compatibility agent for cis 1,4-polybutadiene and 1,4-polybutadiene cis-specific rubbers for materials having glass transition temperatures within a range of about -75 ° C 110 ° C, particularly when the two polybutadiene rubbers are used in combination with each other. The presence of 1, 4-polybutaideon trans rubber in the floor rubber composition is important because it allows the use of higher levels (amounts) of polybutadiene rubbers for improved wear resistance (DIN abrasion values) without loss of resistance to tearing. It will be noted that the use of the individually prescribed elastomers is not novel for a tire floor rubber composition or for an external side wall rubber composition of the tire. The novelty lies in the combination of the specific elastomers for materials together with the specific low levels for specific carbon black materials and the low to nonexistent levels of rubber processing oil combined with the specialized method of preparing the rubber compositions . The use of relatively low levels of the specific carbon black in the prescribed tire floor rubber composition is important because it promotes relatively high rebound values to increase (reduce) the rolling resistance of the rims and the durability of the rim promoting a reduced heat build-up and, consequently, a cooling rolling temperature for a tire floor rubber composition. The selection of a relatively low specific range of black (s) of smoke itself is important because the carbon black (a) structured higher (finer particle size), characterized in that it has the relatively high DBP value within a range of about 110 to about 10O and a related Iodine index value in a range of 90 to 150, promotes a value of highest abrasion resistance according to DIN for rubber composition, while carbon black (b) of lower structure (larger particle size) characterized by a significantly lower DBP value within a range of about 70 to about 140 and a related Iodine index value of about 30 to about 90 are considered here as more suitable for other rim components, particularly a rubber composition for external side wall as well as industrial products such as belts and hoses. Representative examples of said specific carbon black for materials (a) for tire floors are, for example, N121, NllO and N234. It will be noted that the use of such carbon blacks for rubber compositions for tire flooring itself is not a novelty. The novelty lies in the use of such carbon blacks with the specific combination for elastomer materials as well as the relatively limited use of rubber processing oil in combination with the restrictive method of preparation.

The characterizations of DBP and Iodine value for carbon blacks and methods for their determination can be easily found in The Vanderbilt Handbook, Thirteenth Edition (1990), pages 416-419. For a better understanding of the prescribed selection of the defined carbon blacks, reference is made to the accompanying drawing. In the drawing, a graphic representation is presented in which blacks of smoke are illustrated and differences in terms of their value of DBP and index of -Yodo. More specifically, the aforementioned carbon black (a) is represented by the A-frame having a DBP value within a range of about 110 to about 160 cc / 100 gm and an iodine number within a range of about 90. to about 150. Representatives of these carbon blacks are N347, N299, N220 and NllO. More specifically, the above-mentioned carbon black (b) is represented by the table B having a DBP value within a range of about 60 to about 130 cc / 100 gm and an Iodine index within a range of about 25 to about 85. Representatives of such carbon blacks are N762, N660, N550, N351, N330 and N326. Therefore it can be seen more clearly in the drawing that a carbon black (a) and a carbon black (b) are mutually exclusive. It is readily understood by those skilled in the art that rubber composition for floor rubber could be obtained by methods generally known in the rubber composition art, such as by mixing the various vulcanizable constituent rubbers with sulfur with various additive materials employed usually as for example curing aids, such as sulfur, activators, retardants and accelerators, processing additives such as oils, resins including tackifying resin, silica and plasticizers, fillers, pigments, fatty acids, zinc oxide, waxes, antioxidants and antiozonants, peptizing agents and reinforcing materials such as silica and carbon black. As those skilled in the art know, according to the intended use of the material vulcanizable with sulfur and vulcanized with sulfur (rubber), the additives mentioned above are selected and commonly used in conventional amounts. In practice, said 1,4-polybutadiene trans resin preferably has a microstructure characterized in that it has a 1,4-polybutadiene trans content of from about 80 to about 90%, a 1,2-vinyl content of about 10 about 15% and a cis 1,4- content of about 1 to about 5%. Preferably, said 1,4-polybutanene trans resin is further characterized in that it has a number average molecular weight (Mn) within a range of about 150,000 to about 210,000. Said 1,4-polybutadiene trans resin preferably has an index of heterogeneity (Hl) within a range of about 2 to about 2.5 which is representative of a relatively narrow index of heterogeneity (a ratio between its average molecular weight number). (Mn) and its average molecular weight (Mw) An index of narrow heterogeneity is often desirable for several purposes, preferably said 1,4-polybutadiene trans resin has a melting point in the range of about 38 ° to about 42 ° C. Typically, said 1, 4-polybutadiene trans has a glass transition temperature within a range of about -70 ° C to about -80 ° C. While all aspects of the present invention may not be fully understood , it is believed that the aforementioned microstructure of the 1,4-polybutadiene trans resin contributes substantially to its thermoplastic resin type property, parti particularly its relatively hard and rigid appearance property at temperatures below about 30 ° C, such as at temperatures of about 20 ° to about 25 ° C, and its melting point property within a temperature range of about 30 ° C at approximately 50 ° C. It is also considered that its average molecular weight (Mn) range as well as its relatively narrow index of heterogeneity may contribute in some way to its aforementioned property of resin type before it is mixed with other elastomers. The formation of a rim component is contemplated by conventional means such as for example by extrusion of rubber composition to provide rubber components which have not been vulcanized, such as, for example, a rim floor. Such formation of a tire floor is well known to those skilled in the art. It is understood that the rim, as a manufactured article, is prepared by the formation and curing with sulfur of all its components at an elevated temperature (for example, 140 ° C-180 ° C) and under a high pressure in a suitable mold. Said practice is well known to those skilled in the art. Thus, in a more specific aspect of this invention, somehow according to the aforementioned selection of the carbon black, there is provided a rim having a floor component, ie, an outer circumferential floor, provided to be in contact with the floor, formed of a rubber composition prepared in accordance with this invention. In a further aspect of this invention, rims with components other than floors as well as components of industrial products are contemplated. Representative examples of said smaller amount of additional diene-based elastomers, ie up to a maximum of 5 phr if used, are, for example, vinyl polybutadiene rubbers, particularly medium to high vinyl polybutadiene rubbers containing about 30% by weight. about 85% vinyl 1,2- content, styrene / butadiene copolymers either prepared by aqueous emulsion or by polymerization in organic solvents, isoprene / butadiene copolymers, styrene / isoprene copolymers as well as styrene / isoprene copolymers / butadiene. The precipitated silicas are, for example, the silicas obtained by the acidification of a soluble silicate, for example, sodium silicate. Such precipitated silicas are well known to those skilled in the art. Such precipitated silicas can be characterized, for example, because they have a BET surface area, as measured using nitrogen gas, preferably within a range of about 40 to about 600, and more usually within a range of about 50 to about 300 square meters per gram. The BET method for measuring surface area is described in the Journal of the American Chemical Society, volume 60, page 304 (1930). The silica can also be characterized in a typical manner because it has an absorption value of dibutyl phthalate (DBP) within a range of about 100 to about 400, and more usually of about 150 to about 300. Silica is conventionally employed in combination with a silica coupler to connect the silica with or these elastomer (s) and, therefore, increase the elastomer reinforcing effect of the silica. Said coupling agents can, for example, be premixed or pre-reacted with the silica particles or they can be added to the rubber mixture during rubber / silica processing or in the mixing step. If the cloning agent and silica are added separately to the rubber mixture during rubber / silica mixing or processing step, it is considered that the coupling agent is then combined in situ with the silica. Particularly, said coupling agents are sometimes composed of a silane having a constituent component, or a portion (the silane portion) capable of reacting with the surface of the silica, i.e., silanol groups on the surface of the silica and, also, a component constituent, or portion, capable of reacting with the rubber, particularly a vulcanizable rubber with sulfur containing carbon-carbon double bonds, or unsaturation. In this way, then the coupler acts as a connection bridge between the silica and the rubber and consequently increases the rubber reinforcement aspect of the silica. Various coupling agents are presented for use in the combination of silica and rubber such as for example silane coupling agents containing a polysulfide component or structure such as for example a bis (3-alkoxysilylalkyl) polysulfide, where the alkyl radicals for the alkoxy group are selected from methyl and ethyl radicals, the alkyl radical for the silane portion are selected from ethyl, propyl and butyl radicals, and the polysulphide bridge contains an average of (a) 2 to 6, and an average of 2.1 to 2.8, of sulfur atoms either (b) from 2 to 8 and an average of 2.3 to 4.5 sulfur atoms. A representative example of said coupling agent is a bis- (3-triethoxysilylpropyl) polysulfide having (a) from 2 to 6, and an average of from 2.1 to 2.8, sulfur atoms in its polysulphide bridge or (b) 2 to 8, and an average of 3.5 to 4.5 sulfur atoms in its polysulfide bridge. It will be readily understood by those skilled in the art that the rubber composition will be formed by methods generally known in the art of forming rubber, such as by mixing the various vulcanizable constituent rubbers with sulfur with various additive materials commonly employed as, for example, auxiliaries. curing agents such as sulfur, activators, retardants, and accelerators, processing additives such as oils, resins including tackifying resins, silicas and plasticizers, fillers, pigments, fatty acid, zinc oxide, waxes, antioxidants and antiozonants, peptization, as well as reinforcement materials such as black smoke. As those skilled in the art know, according to the intended use of the vulcanizable material with sulfur and vulcanized with sulfur (rubber), the additives mentioned above are selected and commonly used in conventional amounts. A number of processing aids for a practice of this invention may be from about 0 to about 10 phr. Said processing aids may include, for example, aromatic, naffenic, and / or paraffinic processing oils. Typical amounts of antioxidants comprise from about 1 to about 5 phr. Representative antioxidants may be, for example, diphenyl-p-phenylenediamine and others such as, for example, those presented in Vanderbilt Rubber Handbook (1978), pages 344-346. Typical amounts of antiozonants comprise from about 1 to 5 phr. Typical amounts of fatty acids, if employed, which may include stearic acid, comprise from about 0.5 to about 3 phr. Typical amounts of zinc oxide comprise from about 1 to about 5 phr. Typical amounts of waxes comprise from about 1 to about 5 phr. Microcrystalline waxes are frequently used. Typical amounts of peptizing agents comprise from about 0.1 to about 1 phr. Typical peptizing agents may be, for example, pentachlorothiophenol and dibenzamidodiphenyl disulfide. The vulcanization is carried out in the presence of a sulfur vulcanization agent. Examples of sulfur vulcanization agents include elemental sulfur (free sulfur) or sulfur donor vulcanizing agents, for example, an amine disulfide, polymeric polysulfide, or sulfur olefin adducts. Preferably, the sulfur vulcanization agent is elemental sulfur. As known to those skilled in the art, sulfur vulcanization agents are employed in an amount ranging from about 0.5 to about 4 phr, or, in some circumstances, up to about 8 phr, with a range of about 1.5 to about 2.5, sometimes from about 2 to about 2.5. Accelerators are used to control the time and / or temperature required for vulcanization and to improve the properties of the vulcanized product. In one embodiment, a single accelerator system, i.e., primary accelerator, may be employed. Conventionally and preferably, a primary accelerator or several primary accelerators are employed in total amounts that are within a range of from about 0.5 to about 4, preferably from about 0.8 to about 1.5 phr. In another embodiment, combinations of a primary accelerator and a secondary accelerator can be employed with the secondary accelerator being used in smaller amounts (from about 0.05 to about 3 phr) in order to activate and improve the properties of the vulcanized product. It can be expected that combinations of these accelerators will produce a synergistic effect on the final properties and are in some way better than the products produced by the use of any of the accelerators alone. In addition, delayed action accelerators can be employed that are not affected by normal processing temperatures but produce a satisfactory cure at usual vulcanization temperatures. Vulcanization retardants can also be used. Suitable types of accelerators that can be employed in the present invention are amines, disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides, dithiocarbamates and xanthates. Preferably, the primary accelerator is a sulfenamide. If a second accelerator is employed, the second accelerator is preferably a guanidine, dithiocarbamate or thiuram compound. The presence of relative amounts of the above additives, with the exception of rubber processing oil, are not considered as an aspect of the present invention that focuses more on the preparation of rim floors made with a rubber composition that is quantitatively reinforced with silica, with only a minimum of carbon black, and containing a cis 1,4-polyisoprene rubber with cis 1,4-polybutadiene rubber or a 1,4-polybutadiene trans and 1,4- rubber rubber cis polybutadiene, particularly when the prescribed mixing process is employed. The mixture of the rubber composition can preferably be achieved through the aforementioned cascade mixing process. For example, the ingredients can be mixed in at least 3 stages, that is, at least two nonproductive steps (preparation) followed by a productive (final) mixing step. The final curing agents are typically mixed in the final stage which is conventionally known as the "productive" or "final" mixing stage where mixing at a temperature typically occurs., or else ultimate temperature, lower than the mixing temperature or the mixing temperatures of the preceding nonproductive mixing stage (s). The term "non-productive" and "productive" mixing stages are well known to those skilled in the art. In one aspect of the invention, it is desired to provide sulfur-cured (cured) diene-based rubber compositions which may have the following combination of physical properties limits for use in rim floors which may sometimes be referred to herein as "white properties". " Three properties are represented in the following table A: Table A: Properties white Values Module, 300%, Mpa at least 7.5 and within a Range of 7.5 to 14 Bounce at 100 ° C at least 52, and within a range of 52 to 70% Hardness, Shore A (100 ° C) at least 54 and within a range of 54 to 72 Abrasion, DIN (ce) maximum of 62, and within a 25 to 62g E'a 0 ° C (MPa) at least 24, and within a range of 24 to 50 Resistance to rupture, at least 150, and within a 95 ° C (N) Range of 150 to 350 These white properties are considered significant because they are related with the desired physical properties, particularly to predict the proper performance of the rim floor. Particularly, a module greater than 7.5 MPa (a range of 7.5 to 14 MPa) because it is considered here that it is related to better handling characteristics and (less abrasion). A rebound value at 100 ° C- of at least 52% (a range of 52 to 70%) is important because it is considered here that it is related to better characteristics of rolling resistance and thermal accumulation of rim (reduced). A Shore A hardness value at 100 ° C of at least 54 (a range of 54 to 72) is important because it is considered here to be related to better characteristics of abrasion resistance (less wear) and better rim handling. A resistance to abrasion according to DIN of a maximum of 62 ce (a range of 25 to 62 cubic centimeters) is important because it is considered here that it is related to a better characteristic of resistance to gases (reduced wear). An E 'value at 0 ° C of more than 24 MPa (a range of 24 to 50 MPa) is important because it is considered here to be related to an improved feature of irregular floor wear (less wear). The E 'value, as known to those skilled in the art, is related to a lower deformation rubber composition rigidity. The value of tear resistance (detachment adhesion test) of at least 150 (a range of 150 to 250) is important because it is considered here to be related to better fatigue resistance characteristics and (reduced) formation of pieces of tire floor. In practice, while it is considered here that the white properties of the aforementioned rubber composition are individually important to refer to the particularly desired rim characteristics, it is a desirable feature of this invention that all the aforementioned white properties are obtained for a rubber composition through the practice of this invention. The invention will be better understood with reference to the following examples in which the parts and percentages are by weight unless otherwise indicated. EXAMPLE I In this example, the rubber compositions illustrated in Table 1 were prepared in an internal rubber mixer (a Banbury mixer) using either (1) a two-stage mixing process (identified here as sample A) or well (2) a 3 stage cascade mixing process wherein a carbon black reinforcement is mixed with the elastomer or the elastomers in a first mixing step followed by mixing, in a second stage of separate mixing, of silica and silica coupler (identified here as sample B). Particularly, the two-stage mixing process employs two separate sequential stages of addition of materials, i.e., a non-productive mixing stage (at high temperature and without curing agents) followed by a final productive mixing step (at a temperature minor and with the addition of curing agents). Said sequential rubber mixing process is well known to the person skilled in the art. The non-productive rubber composition (without curing agents (sample A) was mixed for about 3 minutes at a temperature of 160 ° C. In a productive, subsequent and final mixing step, curing agents were added and the rubber composition It was mixed for approximately 2 minutes at a temperature of 120 ° C. Sample B used a cascade mixing process involving 3 separate sequential mixing steps of addition of materials (in an internal rubber mixer), ie two sequential nonproductive stages followed by a productive mixing particularly, for the first non-productive stage, natural rubber and cis 1,4- polybutadiene were mixed with the carbon black and other compounding materials for about 3 minutes at a temperature of approximately 160 ° C. In the second stage of non-productive, sequential mixing, silica and coupling agent were added to the obtained composition. It starts from the first non-productive stage while mixing for about 3 minutes at a temperature of 160 ° C. The composition of the non-productive second stage was then mixed in a final production step with curing agents over a period of about 2 minutes at a temperature of about 120 ° C. Table 1 illustrates the ingredients used to prepare the rubber compositions of samples A and B. Table 1 Sample AB First non-productive stage Natural rubber 1 50 50 1,4-polybutadiene cis 2 50 50 Silica 3 30 0 Coupling agent 4 6 0 Black fumar5 30 30 Aromatic processing oil 10 10 Cera6 1. 5 1. 5 Zinc Oxide 3 3 Fatty Acid7 3 3 Second nonproductive mixing Silica8 0 30 Coupling agent'1 0 6 Productive Mixing Sulfenamide Accelerator 1.3 1.3 Sulfur 1 1 Antidegradants9 3.5 3.5 1. Natural rubber (1, 4-polyisoprene cis rubber ) - as TTR20 - Technical Thai Rubber. 2. High cis 1,4-polybutadiene rubber (BUDENE ® 1208) Goodyear Tire & Rubber Company. 3. Zeosil 1165 MP from Rhone-Poulenc. 4. X50S of Degussa B bH, in the form of a 50/50 mixture of bis- (3-triethoxysilylpropyl) tetrasulfide and carbon black and, therefore, is 50% active as a coupling agent. 5. N121, carbon black SAF. 6. Microcrystalline / paraffinic mixture. 7. Stearic acid primarily. 8. Obtained as Zeosil 1165 MP from Rhone-Poulenc. 9. Amine-type antioxidant / antiozonant. The rubber compositions of Table 1 were cured for a period of about 36 minutes at a temperature of about 150 ° C. Several resulting physical properties appear in the following table 2.

Table 2 Sample A B Mixing procedure Standard Cascading Rheometer, 150 ° C Torque torque Max, dNm 14.1 18.1 Torque torque Min, dNm 4.0 4.0 Torque torque delta, dNm 10.1 14.1 T90, minutes 21 21.5 Effort-Deformation Resistance to tension, MPa 18.3 18.9 Elongation at break,% 641 654 Module to 100% 1.5 1.8 Module at 300% 6.7 7.5 Bounce 100 ° C,% 54 53 Shore A hardness, 100 ° C 50 54 Reovibron E 'at 60 ° C 8.7 13.5 E'a 0 ° C 16.0 24.4 Tan. Delta at 60 ° C .150 .137 Tan. Delta at 0 ° C .153 .138 Abrasion DIN 36 35 Resistance to tearing (N) Adherence to detachment, 95 ° C 389 312 After evaluation of the cured properties of the compositions illustrated in figure 2, it is important to reiterate the desired white properties (table A), ie , a modulus at 300% of at least 7.5 MPa (range of 7.5 to 14), a rebound at 100 ° C of at least 52% (range of 52 to 70%), a Shore A hardness of at least 54 (range of 54 to 72), an abrasion value according to DIN of less than 62 cm3 (range of 62 to 25), a value of elastic disc modulus, E 'of at least 24 (range of 24 to 50 at 0 ° C and a resistance of tearing by peeling at 95 ° C of at least 150 Newtons (range of 150 to 350) The composition of sample A prepared by the two-stage mixing process did not meet these objectives due to the low values for the module at 300 % (6.7 MP), hardness (50) and viscoelastic modulus E 'at 0 ° C (16 MPa) .The relative physical properties of sample B, however , prepared by the prescribed 3 stage cascade mixing process, the carbon black is mixed in a separate mixing step before the addition of silica and coupler, meet all the aforementioned property objectives and represents a mixing process preferred for the preparation of the compounds of this invention. The superior properties of the vulcanized product of sample B compared to sample A were not expected, without experimentation, since both rubber compositions contained the same ingredients in the same proportions. EXAMPLE II In this example, rubber compositions similar to those described in Example I were prepared using the cascade mixing method in accordance with that described for the preparation of Sample B in Example I. This mixing procedure uses 3 steps Sequential sequential addition of materials, namely 2 sequential nonproductive stages followed by a productive stage. In this example, the order of addition of the fillers was examined, namely, carbon black, in the first non-productive stage followed by silica in the non-productive second stage (sample C and D) or silica in the first stage not productive followed by carbon black in the non-productive second stage (sample E). The rubber composition was mixed in the non-productive mixing stages for about 3 minutes each at a temperature of about 160 ° C, unless it was "heat treated" as for example in the case of samples D and E where the Mixing time of the non-productive stage in which the silica was added was extended for about 7 minutes while maintaining a temperature of about 160 ° C.

The use of a constant mixing temperature was achieved by varying the rotor speed of the internal mixer and is referred to herein as "heat treatment". Thus, for the sample D a thermal treatment was applied to the non-productive second stage, while for the sample E, a thermal treatment was applied to the non-productive first stage. The production steps were mixed in accordance with that described in example I. Table 3 describes the rubber compositions for this example. Table 1 Sample CDE First non-productive stage Natural rubber1 50 50 50 1, 4-polybutadiene cis2 50 50 50 Silica3 0 0 30 Coupling agent4 0 0 6 Carbon black "30 30 0 Aromatic processing oil 10 10 10 Cera6 1.5 1. 5 1 .5 Zinc Oxide 3 3 3 Fatty Acid7 3 3 3 Non-productive second stage Silica8 30 30 0 Coupling agent4 6 6 0 Carbon black 0 0 30 Production stage Sulfenamide accelerator 1.3 1.3 1.3 Sulfur 1 1 1 Antidegradants9 3.5 3.5 3.5 l.Hule natural (cis 1,4-polyisoprene rubber) - as TTR20 - Technical Thai Rubber 2. High cis 1,4-polybutadiene rubber (BUDENE ® 1208) Goodyear Tire & Rubber Company. 3. Zeosil 1165 MP from Rhone-Poulenc. 4. X50S of Degussa BmbH, in the form of a 50/50 mixture of bis- (3-triethoxysilylpropyl) tetrasulfide and carbon black and, therefore, is 50% active as a coupling agent. 5. N121, carbon black SAF. 6. Microcrystalline / paraffinic mixture. 7. Stearic acid primarily. 8. Obtained as Zeosil 1165 MP from Rhone-Poulenc. 9. Amine-type antioxidant / antiozonant. The rubber compositions of Table 1 were cured for a period of about 36 minutes at a temperature of about 150 ° C. Several resulting physical properties appear in the following table 2. Table 4 Sample C D E Stage of addition of carbon black 1 1 2 Stage of addition of silica 2 2 1 Heat treatment stage nniinngguunnaa 2 1 Rheometer, 150 ° C Torque torque Max, dNm 15.6 14.3 14.7 Torque torque Min, dNm 3.5 2.8 3.2 Torque torque delta, dNm 12.1 11.5 11.5 T90, minutes 19 17 17.5 Effort-Deformation Resistance to tension, MPa 19.2 19.9 18.7 Elongation at break,% 621 586 597 Module at 100% 1.9 1.8 1.9 Module at 300% 8.3 9.0 8.6 Bounce 100 ° C,% 59 63 58 Shore A hardness, 100 ° C 55 54 54 Abrasion DIN 37 33 31 Resistance to tearing (N) Resistance to detachment, 235 151 210 95 ° C The three samples in table 4 present properties within the range of values that were established as objectives of table A. Sample C (without heat treatment) and sample B (with heat treatment in the second non-productive stage) they were prepared by the same filler addition sequence, that is, addition of carbon black in the non-productive first stage and addition of silica in the non-productive second stage. A heat treatment of sample D gave a slightly higher rebound value compared to sample C (63% versus 59%) and a slightly improved abrasion resistance value (minor wear) (33 versus 37), but presented a limited tear strength (less resistance to tearing) (171 versus 235). Accordingly, it is not observed that a treatment of these cascaded samples is a critical factor in obtaining the property objectives of this invention. Likewise, the properties of sample D (addition of carbon black in a first stage, addition of silica in a second stage) and sample E (addition of silica in a first stage, addition of carbon black in a second stage) They are very similar. Both samples were heat treated. Sample D had a slightly higher rebound value than sample E (63 versus 58), but worse tear resistance (171 versus 210). However, the mixing sequence used for sample C and for sample D is preferred compared to the mixing sequence that was used for sample E since the addition of carbon black in the first stage followed by silica in the second stage provides superior processing behavior of the non-productive and productive compounds compared to the immersed addition order of fillers. Samples C and D were less fragmented when they were removed from the internal mixer and showed a better subsequent behavior in a laminator (formation of sheets from a two-roll laminator). EXAMPLE III In this example, a rubber composition containing carbon black and silica fillers was prepared with natural rubber, 1,4-polybutadiene cis rubber and trans 1,4-polybutadiene rubber. The rubber composition contained the materials illustrated in Table 5 and was prepared using the three stage cascade mixing process described in Example I. This composition was not thermally treated. The composition is referred to herein as Sample F and is illustrated in the following table 5. Table 5 Sample F First non-productive stage Natural rubber 1 20 1, 4-polybutadiene cis 2 50 1, 4-Polybutadiene Trans' 30 Black smoke "30 Oil of aromatic processing 10 Cera7 1.5 Zinc Oxide 3 Fatty Acid 8 3 Non-productive second stage Silica4 30 Coupling agent5 6 Productive stage Sulfenamide accelerator 1.3 Sulfur 1.0 Antidegradants9 3.5 1. TTR20 - Technical Thai Rubber 2. High cis 1,4-polybutadiene rubber (BUDENE ® 1208) by Goodyear Tire &; Rubber Company 3. High 1, 4-polybutadiene rubber (experimental polymer: 80% Trans). 4. Zeosil 1165 MP from Rhone Poulenc, 5. X50S from Degussa GmbH, a 50/50 mixture of bis (3-triethoxysilylpropyl) tetrasulfide and carbon black and, therefore, 50% active as a coupling agent. 6. Carbon black NI21 of SAF 7. Mixture microcrystalline / paraffinic. 8. Stearic acid primarily. 9. Amine-type antioxidant / antiozonants Sample F is similar to sample B in Table 1, but 30 phr of NR (natural rubber) is replaced by 30 phr of 1,4-trans polybutadiene (trans-BR) to provide an elastomer composition of 20/50/30 natural rubber / 1,4-polybutadiene cis / 1, 4-polybutadiene trans. The rubber composition of Table 5 was cured for about 36 minutes at a temperature of about 150 ° C. The physical properties are shown in Table 6 below. Table 6 Sample F Natural rubber 20 BR cis 50 BR Trans 30 Effort-Deformation Tensile strength, Mpa 16.7 Elongation at break,% 583 Module at 100% 2.1 Module at 300% 7.7 Rebound 100 ° C,% 56 Shore hardness A, 100 ° C 60 Reovibron E 'at 60 ° C 17.9 E' at 0 ° C 48.5 Tan. Delta at 60 ° C .118 Tan. Delta at 0 ° C .113 Abrasion DIN 29 Resistance to tearing Resistance to peeling, 95 ° C 168 Sample F containing 30 phr of transbron BR together with 20 phr of NR and 50 phr of cis BR presented a much higher viscoelastic modulus, E 'at 0 ° C than sample B (50 phr NR / 50 phr BR cis ) of Table 1 (48.5 versus 24.4 MPa), as well as a higher hardness (60 versus 54) and higher bounce (56 versus 53). All the physical properties of sample F meet the objectives in terms of properties. Accordingly, it can be concluded that the addition of BR trans to the rubber compositions of this invention offers the required objectives in terms of properties with the benefit of a very high viscoelastic modulus value and a high hardness. EXAMPLE IV In this example, rubber compositions containing 50 phr of natural rubber and 50 phr of cis 1,4-polybutadiene with carbon black and / or precipitated silica reinforcement were prepared.

The rubber compositions contained the materials illustrated in Table 7 and were prepared in an internal rubber mixer as in Example I for the 3 stage cascade mixing process. Rubber compositions are known herein as G-K samples. Particularly, sample G contained 60 phr of a carbon black of SAF, sample K contained 60 phr of silica and samples H, I and J contained mixtures of carbon black and silica. Table 7 Sample GHJK First non-productive stage Natural rubber1 50 50 50 50 50 1, 4-polybutadiene 50 50 50 50 50 cis silica "0 0 0 15 30 coupling agent 2 4 4 carbon black film5 30 30 30 15 0 nicotinamide 2 2 2 2 2 process oil5 5 5 5 5 aromatic wax wax 1.5 1.5 1.5 1.5 1.5 zinc oxide 3 3 3 3 3 fatty acid 3 3 3 3 3 second stage non-productive silica 0 15 30 30 30 carbon black 30 15 0 0 0 coupling agent 2 4 4 4 ing4 Production stage Accelerator of 1 1 1 1 1 sulfenamide sulfur 1 1 1 1 1 sulfur antidegrandante8 3.5 3.5 3.5 3.5 3. 1. TTR20 - Technical Thai Rubber 2. Rubber of cis 1, 4 - high polybutadiene (BUDENE ® 1208) from Goodyer Tier &Rubber Company 3. Zeosil 1165 MP from Rhone-Poulenc 4. X50S from Degussa GmbH, in the form of a 50/50 mixture of bis- (3-tietoxysilylpropyl tetrasulfide ) and carbon black and, consequently, 50% active as a coupling agent 5. Carbon black NI21 from SAF 6. Microcrystalline / paraffinic mixture 7. Obtained as Zeosil 1165 MP from Rhone-Poulenc. 8. Amine-type antioxidant / antiozonant. The rubber compositions of Table 7 were vulcanized (cured) for about 36 minutes at a temperature of about 150 ° C. The physical properties appear in the following table 8. Table 8 Sample GHIJK Carbon black 60 45 30 15 0 Silica 0 15 30 25 60 Coupling agent 2 4 6 • 8 (50%) rheometer 150 ° C Max torque, 50.7 49.3 45 46.9 53 dNm Torque torque Min, 18.0 16.7 13.4 15.8 21 dNm Torque torque delta 32.7 32.6 31.6 31.1 32 dNm T90, minutes. 10.5 11.5 16 20 26.5 Effort-Deformation Resistance to 18.7 18.3 18.3 17.5 17.1 tension, Mpa Elongation to the rom- 500 482 529 570 664 Pepper,% Module to 100% 2.6 2.7 2.5 2.2 2.0 Module to 300% 11.3 11.5 10.3 9.0 7.3 Bounce 100 ° C,% 51.8 55.9 57.3 58.1 56.4 Shore A hardness, 100 ° C 62 62 61 59 63 Reovibron E'a 60 ° C, Mpa 30.1 22.2 20.0 18.0 21.5 E'a 0 ° C, Mpa 44.7 37.9 30.0 26.4 33.0 Tan. Delta at 60 ° C .107 .119 .109 .105 .105 Tan. Delta at 0 ° C .094 .113 .106 .111 .107 Abrasion DIN 50 53 56 53 65 Tear resistance (N) Resistance to 122 127 115544 116655 224 detachment, 95 ° C The properties of samples G and H did not meet the objective values of Table A due to low values for tear resistance, ie 122 and 127 Ne tons, respectively. Sample G also had a rebound value of 51.8 that is lower than the target value. Sample K also failed to meet these objectives due to a low modulus value at 300%, 7.5 MPa, and a higher DIN abrasion value, 65. The properties of samples I and J meet all established values and indicate optimum properties in a 50/50 mixture of natural rubber and 1,4-polybutadiene cis, when the total carbon black and silica was about 60 phr and the ratio between silica and carbon black is 1/1 to 3/1. Example V In this example, rubber mixture compositions containing 40 to 60 phr of natural rubber and therefore 60 to 40 phr of 1,4-polybutadiene cis rubber together with 30 phr of carbon black and silica phr. Two types of carbon blacks (SAF and HAF) and two types of silica were used for their evaluation. The rubber compositions are illustrated in Table 9 and were prepared using the cascade mixing procedures of Example I. The rubber compositions are identified herein as samples L-P. Table 9 Sample L M N 0 First non-productive stage Natural rubber1 40 50 60 50 50 1, 4-polybutadiene 60 50 40 50 50 CB A3 3 300 30 30 0 30 CB A4 0 0 0 0 30 0 process oil5 5 5 5 5 5 aromatic phase nicotinamide 2 2 wax 1.5 1.5 1.5 1.5 1.5 zinc oxide 3 3 3 3 3 fatty acid 3 3 3 3 3 second stage non-productive silica A5 30 30 30 30 0 silica A6 0 0 0 0 30 coupling agent 5 5 5 5 ment Production stage Accelerator of 0.8 0.8 0.8 0.8 0.8 sulfenamide sulfur 0.8 0.8 0.8 0.8 0.8 antidegrandante 3.5 3.5 3.5 3.5 3.5 hexamethylene tetramine 2 2 2 2 2 1. TTR20 - Technical Thai Rubber. 2. BUDENE ® 1208 from Goodyear Tire & Rubber Company. 3. Smoke Black NI21 from SAF. 4. Smoke Black N347 from HAF 5. Zeosil 1165 MP from Rhone-Poulenc. 6. Hi-Sil 210 from PPG. In the following table 10- various physical properties of rubber compositions cured with sulfur are shown. Table 10 Sample LMNOP NR / BR cis 40/60 50/50 60/60 50/50 50/50 CB-A / CB-B 30/0 30/0 30/0 0/30 30/0 Silica A / Silica B 30/0 30/0 30/0 30/0 0/30 Rheometer 150 ° C Torque torque Max, 43.5 39.8 41 40.5 44 dNm Torque torque Min, 13.6 12.0 12.5 12 13 dNm Torque torque delta 29.9 27.8 28.5 28.5 31 dNm T90, minutes. 17.0 17 16.5 15 19.5 Effort-Deformation Resistance to 16.5 18.1 17.5 18.0 tension, Mpa Elongation at rom- 544 558 551 540 564 Pepper,% Module at 100% 2.3 2.2 2.4 2.4 2.4 Module at 300% 9.0 9.3 10.2 9.8 9.4 Bounce 100 ° C,% 53 55 55 56 52 Shore A hardness, 100 ° C 62 59 59 61 Reovibron E'a 60 ° C, Mpa 20.8 19.2 21.0 17.8 19.9 E'a 0 ° C, Mpa 33.2 29.6 30.7 30.2 30.7 Tan. Delta at 60 ° C .124 .122 .111 .118 .109 Tan. Delta at 0 ° C .112 .115 .108 .120 .106 Abrasion DIN 47 62 69 58 61 Tear resistance (N) Resistance to 171 178 161 156 205 Detachment, 90 ° C All rubber compositions with the exception of sample N in Table 10, present the required property objectives. The sample N has an abrasion value according to DIN higher than the target value for this property and could be expected to have a floor wear resistance value below the value of the other samples (greater wear). This would indicate that the upper limit for the natural rubber content is below about 60 phr. While some representative embodiments and details were presented for the purpose of illustrating the invention, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit or scope of the invention.

Claims (10)

1. CLAIMS A method for preparing a rubber composition characterized in that it comprises, based on 100 parts by weight (phr) of diene-based elastomers, (a) the mixture of (1) about 20 to about 60 phr of elastomer of 1, 4 cis -polysisoprene having a glass transition temperature within a range of about -65 ° C to about -75 ° C and (2) about 40 to about 80 phr of (a) 1, 4-polybutadiene trans rubber having a glass transition temperature within a range of about -70 ° C to about -80 ° C and a cis 1,4-polybutadiene rubber having a glass transition temperature within a range of about -100 ° C at about -110 ° C in a weight ratio between 1,4-polybutadiene trans and 1,4-polyisoprene cis within a range of about 3/1 to about 1/3 or (b) rubber of 1 , Cis-4-polybutadiene which has a transition temperature to glass dent from a range of about -100 ° C to about -110 ° C, (B) from about 40 to 80 phr of carbon black and precipitated silica reinforcing filler comprising from about 20 to about 60 phr of precipitated silica and from about 15 to about 60 phr of carbon black and (c) at least one silica coupling agent having a portion that reacts with silanol groups on the surface of said silica and an additional interactive portion with said elastomers and (D) from 0 to about 10 phr of rubber processing oil; wherein said rubber black is selected from a first carbon black having a DBP value within a range of about 100 to about 150 cc / 100 gm and an Iodine index within a range of about 90 to about 150 g / kg or a second carbon black having a DBP value within a range of about 65 to about 130 cc / 100 cm and an Iodine index within a range of about 25 to about 85 g / kg; wherein said method comprises (1) the mixture of said elastomers and carbon black, excluding silica and sulfur curing agent, in an internal rubber mixer in a first mixing stage of internal rubber preparation for a period of about one minute at about 10 minutes at a temperature within a range of about 150 ° C to about 180 ° C, (2) the mixture of said precipitated silica and silica coupling agent, excluding carbon black and sulfur curing agent, in at least one internal rubber mixer in a subsequent mixing stage of internal rubber preparation over a period of about one minute to about 10 minutes at a temperature of about 150 ° C to about 180 ° C; where said oil, if employed, can be added either with carbon black and / or with silica, and (3) the mixture of sulfur curing agent (s) in an internal rubber mixer in a final mixing step. of internal rubber for a period of from about one minute to about 4 minutes at a temperature within a range of about 80 ° C to about 130 ° C; wherein said rubber composition is removed from said internal rubber mixer at the end of each mixing step and cooled to a temperature below 40 ° C.
2. The method of claim 1, characterized in that said coupling agent is a bis (3-trialkoxysilylalkyl) polysulfide wherein the alkyl radicals of the alkoxy groups are selected from methyl and ethyl radicals, the alkyl radical of the silane portion is selected from ethyl, propyl and butyl radicals; and where the polysulfide bridge contains (a) from 2 to 6, and on average from 2.1 to 2.8 sulfur atoms or (b) from 2 to 8 and on average from 3.5 to 4.5 sulfur atoms.
3. The method of any of the preceding claims characterized in that said diene-based elastomers are 1, Cis-4-polyisoprene, said 1,4-polybutadiene trans and said 1,4-cis-polybutadiene.
4. The method of any of the preceding claims 1, 2, characterized in that said diene-based elastomers are 1,4-polyisoprene cis and 1,4-cis-polybutadiene.
5. 5. The method of any of the preceding claims characterized in that said carbon black is said first carbon black.
6. 6. The method of any of the preceding claims characterized in that said carbon black is said second carbon black.
7. The method of any of the preceding claims characterized in that the rubber processing oil is used in an amount of 5 to 10 phr.
8. 8. A rubber composition characterized in that it is prepared by the method of any of the preceding claims.
9. 9. A rubber composition prepared by the method of any of the preceding claims 1-8, characterized in that it is vulcanized with sulfur. A tire characterized in that it has a floor made with the rubber composition of claim 8. 11. A tire characterized in that it has an elaborated floor of the rubber composition of claim 9. 12. A tire characterized in that it has at least one tire. portion of a side wall made from a rubber composition of claim 8. A tire characterized in that it has at least a portion of a side wall made from the rubber composition of claim 9.