Block copolymers for rubber compositions for use in tyres

[0001] (Field of invention) The present invention provides block copolymers for constructing an elastomer matrix of crosslinkable rubber compositions with reduced hysteresis, rubber compositions used in the crosslinked state in tire treads, tita treads and reduced rolling resistance. The present invention relates to a tire including the tire tread shown. (Background of invention) The tire industry is constantly striving to limit fuel economy and reduce the hysteresis of the mixture to protect the environment. This reduction in hysteresis must be achieved while maintaining or improving the processability of the mixture. Many approaches have already been taken to reduce hysteresis. Chain terminal functionalization is of particular interest. Many of the proposed methods involved the search for adjacent functional groups involved in the completion of polymerization that could interact with carbon black, such as those contained in star polymers or tin-coupled polymers. .. European patent specification EP-A-709235 can be given as an example. Also, other functional groups that interact with carbon black, such as 4,4'-bis (diethylaminobenzophenone) (also known as DEAB) or other amine functional groups, are attached to the chain ends. FR-A-2526030 and US-A-4848511 are examples. [0002] A few years ago, it became possible to use silica, and research is underway to find functional groups that can interact with this filler. FR-A-2740778 discloses, for example, a functional group containing a silanol group, which can be specifically mentioned as this association. Further, US-A-5066721 and US-A-3244664 disclose an alkoxysilane or allyloxysilane functional group. Many of these approaches, regardless of carbon black or silica, result in a true reduction in hysteresis and increase the level of reinforcement of the corresponding composition. Unfortunately, these improvements are often extremely difficult to process in these compositions. Therefore, there is a need for other means for reducing hysteresis without affecting the processing of the mixture. In particular, the use of polymers with low hysteresis potential, especially polyisoprene, proves to be a promising approach. However, the direct use of this type of polymer does not necessarily provide a satisfactory compromise between dynamic modulus and hysteresis. [0003] Attempts have been made to use block copolymers containing polyisoprene blocks to solve this drawback. Block copolymers are generally composed of separated phase materials. The diblock polyisoprene / polystyrene copolymer (this synthesis is comprehensively disclosed in the literature) can be given as an example. These diblock copolymers are known to exhibit beneficial impact resistance. Also disclosed in the literature are block copolymers containing polyisoprene and polybutadiene blocks (abbreviated as IR and BR, respectively). Certain post-polymerization reactions convert these elastomers into thermoplastic materials. For example, when a triblock BR / IR / BR copolymer is hydrogenated, the butadiene fraction forms crystalline polyethylene, while the isoprene fraction gives a rubbery ethylene / butadiene type material. [0004] Also, chlorination of these materials may impart crystallinity to them. Diblock IR / SBR copolymers (copolymers of polyisoprene / styrene and butadiene) are disclosed in European Patent Specification EP-A-438967, especially with respect to reinforcement fillers containing carbon black. The molecular weight of the IR block is preferably 70,000 to 150,000 g / mol, while the molecular weight of the SBR block is preferably 220,000 to 240,000 g / mol. Furthermore, the molecular weight of IR block / molecular weight of SBR block ratio must be greater than 33% and may be 300%. The rubber composition disclosed in this document may have a variable structure, may be layered when the ratio is 33%, and may be spherical when the ratio is 300%. However, for all values of the above ratios in the range of 33% to 300%, the relatively high molecular weight of the IR block is always due to the high content of 1,4-bonds in the IR block, IR and SBR. It should be noted that it results in a marked separation of the corresponding phases. [0005] IR / BR block copolymers are also considered as compatibilizers for blending polyisoprene and polybutadiene. In this regard, a paper by DJ Zanzig, FL Magnus, WL Hsu, AF Halasa, ME Testa (Rubber Chemistry and Technology ", vol. 66, pp. 538-549 (1993)) discloses the use of IR / BR block copolymers containing 80% or 50% IR. At these relative contents, the molecular weight of the IR blocks is always greater than or equal to 200,000 g / mol, so that the blocks of these copolymers also form separate phases. Also, regarding this, a paper by RE Cohen, AR Ramos, (Macromolecules, vol. There are 12, issue 1, 131-134 (1979)). In this paper, the diblock copolymers used include IR blocks with a molecular weight of 104,000 g / mol or 133,000 g / mol. Also, the relatively high mass of the IR and BR blocks provides a strict separation of the phases involved in these two blocks. [0006] (Disclosure of Invention) The applicant of the present application is a copolymer having n blocks (n = 2 or 3) for forming an elastomer matrix of a sulfur crosslinkable rubber composition having reduced hysteresis, and each of the blocks is 15 Containing a diene elastomer with a molar content of units derived from conjugated diene greater than%, at n = 2 or n = 3, at least one block forms the chain ends of the copolymer consisting of polyisoprene, each of the above. Number average molecular weight of polyisoprene terminal block in M_n1Is substantially 2,500 to 20,000 g / mol, and the number average molecular weight of the blocks of the copolymer other than the respective polyisoprene terminal blocks is M._n2It has been found that a copolymer characterized by a substantially 80,000-350,000 g / mol allows for a reduction in hysteresis and a significant optimization of the results for the processability of the rubber composition. [0007] An "essentially unsaturated" diene elastomer that may be used to obtain said blocks other than the IR block (which itself follows this definition) is a copolymerized conjugated diene monomer having 4-12 carbon atoms. It is obtained by copolymerizing any homopolymer obtained by the above, or one or more conjugated diene and itself, or one or more vinyl aromatic compounds having 8 to 20 carbon atoms. Means any copolymer. Suitable conjugated dienes include, in particular, 1,3-butadiene, 2,3-di (C1-C5 alkyl) -1,3-butadiene, such as 2,3-dimethyl-1,3-butadiene, 2,3. -Diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene, 2-methyl-3-isopropyl-1,3-butadiene, phenyl-1,3-butadiene, 1,3-pentadiene And 2,4-hexadiene. [0008] Suitable vinyl aromatic compounds include, for example, styrene, o-, p- or m-methylstyrene, the commercially available mixture "vinyltoluene", pt-butylstyrene, methoxystyrene and vinylmesitylene. In particular, when the hysteresis value of an "essentially unsaturated" diene elastomer, such as a "control" BR or SBR elastomer, is used as a reference, the block copolymers of the present invention can be combined with a corresponding polyisoprene blend, such as IR. Characterized by hysteresis lower than the value of BR or a blend of IR and SBR. It is noted that this reduction in each of the polyisoprene-terminated blocks does not mean that it is possible to excessively significantly reduce the elastic modulus of the resulting block copolymer. On the other hand, according to the present invention, it is noted that it is possible to obtain a non-separated phase of each of the IR terminal blocks and other blocks. In other words, it is noted that phase separation is not a necessary condition to obtain the aforementioned advantages of the present invention achieved by each of the IR terminal blocks. [0009] Preferably, the molecular weight M_n1/ M_n2The ratio between is substantially between 5 and 20%. Also, preferably, the blocks other than the respective polyisoprene terminal blocks contain functional groups capable of interacting with the strengthening filler. The reduction in hysteresis is even more pronounced in this case, resulting in an improvement in workability as compared to conventional functionalized elastomers. The functional group may be capable of interacting with silica and may include, for example, a silanol group or a mono-, di- or trialkoxysilane group. The functional group may also be capable of interacting with carbon black and may include, for example, a C-Sn bond. In this case, this functional group is known per se, general formula: R₃By reaction with an organic halotin-type functionalizing agent, which may be SnCl, or by the general formula: R₂SnCl₂May be organic dihalotin type or formula: SnCl₄It may be obtained by reaction with a tetrahalotin type coupling agent (where R is an alkyl, cycloalkyl or aryl group). Further, the functional group capable of interacting with carbon black may contain an amino group. [0010] Preferably, the blocks other than the respective polyisoprene terminal blocks may be polybutadiene, a copolymer of styrene and butadiene, a copolymer of styrene and isoprene, or a styrene / butadiene / isoprenter polymer. According to other features of the invention, each of the polyisoprene terminal blocks exhibits a vinyl 3,4- and 1,2-bond content between substantially 1-20%. Furthermore, the content of 1,2-bonds in the blocks other than the respective polyisoprene terminal blocks is substantially between 10% and 60%. According to other features of the invention, the respective content of 1,2-bonds and styrene in the block other than the respective polyisoprene terminal block is substantial when it contains a styrene / butadiene copolymer block. Between 10% to 700% and 5% to 50%. [0011] The crosslinkable rubber compositions of the present invention suitable for exhibiting improved processability in the non-crosslinked state and reduced hysteresis in the crosslinked state have an elastomer matrix of the present invention as defined above. It is like containing a block copolymer. According to other features of the invention, the composition may comprise a strengthening filler, wherein the blocks other than the respective polyisoprene terminal blocks are functionalized and coupled to bind to the strengthening filler. It is made into a star or a star. The reinforced filler contains, for example, a large proportion of the inorganic reinforced filler (ie, a mass fraction greater than 50%). In the present invention, the "inorganic reinforcing filler" means a well-known inorganic or mineral filler regardless of its color and its nature (natural or synthetic), and is "white" in contrast to carbon black. Also referred to as a filler or sometimes a "clear" filler, this inorganic filler can itself reinforce the rubber composition for the manufacture of tires without any means other than an intermediate coupling agent. Yes, in other words, its enhancement function can replace the traditional tire-grade carbon black filler. [0012] Preferably, all or at least a large proportion of the reinforced white filler is silica (SiO).₂). The silica used is any reinforced silica known to those of skill in the art, in particular having both a BET surface area and a CTAB surface area of 450 m.²Precipitated or thermally decomposed silica of less than / g may be used, but highly dispersible precipitated silica is preferable. In the present invention, the BET specific surface area is determined by a known method, "The Journal of the American Chemical Society", vol. Brunauer, p. 60, page 309, February 1938. Determined by Emmett and Teller's method and the equivalent Standard AFNOR-NFT-45007 (November 1987). The CTAB specific surface area is the external surface area determined by the same Standard AFNOR-NFT-45007 (November 1987). "Highly dispersible silica" is any silica that has a substantial ability to disaggregate and disperse in an elastomer matrix, which can be observed in flakes by electronic or light microscopy known methods. Means. Examples of such preferred silicas are Akzo's Perkasil KS430, Degussa's BV3380, Rhodia's Zeosil 1165MP and 1115MP, PPG's Hi-Sil 2000, Huber's Zeopol 8741 or 8745 and treated precipitated silica. , For example, but not limited to, the aluminum-doped silica disclosed in EP-A-735088. [0013] The physical state in which the inorganic reinforcing filler is present is not important and is in powder, microbead, granular or spherical form. Of course, "inorganic reinforced filler" also means a mixture of different inorganic reinforced fillers, especially the mixture of highly dispersible silica described above. The reinforcing filler of the rubber composition of the present invention may therefore include a blend (mixture) of the above-mentioned inorganic reinforcing filler plus a small proportion of carbon black (ie, a mass fraction of less than 50%). Suitable carbon blacks are, in particular, types HAF, ISAF and SAF, which are usually used for tires, especially for tire treads. Examples of such carbon blacks include, but are not limited to, N115, N134, N234, N339, N347 and N375. For example, a black / silica blend, or black partially or wholly coated with silica, is suitable for forming a strengthening filler. Also, suitable as a reinforcing filler is silica, for example, carbon black modified with "CRX2000" commercially available from CABOT (disclosed in International Patent Specification WO-A-96 / 37547). However, it is not limited to this. [0014] According to other examples of embodiments of the compositions of the present invention, the reinforced filler comprises a large proportion of carbon black. Suitable carbon blacks are all the carbon blacks mentioned above and are commercially available and are commonly used in tires and especially yaita treads as well as black / silica blends. According to one modified embodiment of the invention, the reinforced filler comprises 50% inorganic reinforced filler and 50% carbon black. For inorganic reinforced fillers such as reinforced silica or alumina, to create a bond or "coupling" between the inorganic filler and the elastomer to facilitate dispersion of the inorganic filler in the elastomer matrix. It is known to those skilled in the art to use coupling agents (inorganic fillers / elastomers), or coupling agents known as binders. [0015] More precisely, the "coupling" agent can establish sufficient chemical and / or physical bond between the filler in question and the elastomer, while the filler into the elastomer matrix. It is understood to mean a reagent that can promote dispersion. Such coupling agents (at least bifunctional) have, for example, the simple general formula: YTX. Here, Y represents a functional group (Y functional) that can be physically and / or chemically bonded to the inorganic filler, for example, the silicon atom of the coupling agent and the hydroxyl (OH) surface of the inorganic filler. Such a bond can be established with a group (eg, surface silanol in the case of silica). X represents a functional group (X functional) that can be physically and / or chemically bonded to the elastomer, for example, by a sulfur atom, and T represents a group that can bond Y and X. Represent. Couplings should not be confused with simple reagents for coating fillers, in particular containing the Y-functionality that is active on the filler but lacking the X-functionality that is active on the elastomer. [0016] Such coupling agents with varying efficacy have been disclosed in numerous literatures and are known to those of skill in the art. In fact, in diene elastomer compositions that can be used in the manufacture of tires, any known coupling agent known to enhance effective bonding or coupling between silica and diene elastomers, such as organosilanes, in particular, It is possible to use polysulfide alkoxysilane or mercaptosilane, or the polyorganosiloxane constituting the above-mentioned X and Y functional groups. Silica / elastomer couplings are particularly disclosed in much literature, the best known being bifunctional alkoxysilanes, such as polysulfide alkoxysilanes. In particular, alkoxysilane polysulfide is also referred to as "symmetrical or asymmetric" due to its specific structure, US-A-3842111, US-A-3873489, US-A-3978103, US-A-3997581, US-A- 4002594, US-A-4072701, US-A-4129585, or the most recent patents or patent applications US-A-5580919, US-A-5583245, US-A-5650457, US-A-5663358, US- A-5663395, US-A-5663396, US-A-5674932, US-A-5675014, US-A-5684171, US-A-5684172, US-A-5696197, US-A-5708053, US-A- 5892085, EP-A-1043357 describes such known compounds in detail. [0017] Particularly suitable for carrying out the present invention are symmetric polysulfide alkoxysilanes that satisfy the following general formula (I), but are not limited to this definition. (I) ZAS_n-AZ (Here, n is an integer of 2 to 8 (preferably 2 to 5), and A is a divalent hydrocarbon group (preferably C).₁~ C₁₈Alkylene group or C₆~ C₁₂Allylene group, more preferably C₁~ C₁₀Alkylene groups, especially C₁~ C₄Is an alkylene group, especially propylene); Z corresponds to one of the following equations: -Si (R)¹) (R¹) (R²), -Si (R)¹) (R²) (R²), -Si (R)²) (R²) (R²) (Here, R¹The groups may or may not be substituted and may be the same or different, C.₁~ C₁₈Alkyl group, C₅~ C₁₈Cycloalkyl group or C₆~ C₁₈Aryl group (preferably C₁~ C₆Alkyl group, cyclohexyl or phenyl group, especially C₁~ C₄Represents the alkyl group of, and also methyl and / or ethyl), R²The groups may or may not be substituted and may be the same or different, C.₁~ C₁₈Alkoxy group or C₅~ C₁₈Cycloalkoxy group (preferably C₁~ C₈Alkoxy group, or C₅~ C₈Cycloalkoxy group, more preferably C₁~ C₄Represents the alkixi group of, especially methoxy and / or ethoxy). [0018] In the case of a mixture of polysulfide alkoxysilanes corresponding to the above formula (I), the average value of "n" is a functional number, preferably fluctuating between 2 and 5, especially in a commercially available mixture. Particularly mentioned polysulfide alkoxysilanes include bis (alkoxy (C).₁~ C₄)-Alkyl (C₁~ C₄) Cyril alkyl (C)₁~ C₄) Polysulfides (particularly disulfides, trisulfides or tetrasulfides), such as bis (3-trimethoxysilylpropyl) or bis (3-triethoxysilylpropyl) polysulfides. Of these compounds, the formula [(C₂H₅O)₃Si (CH₂)₃S₂]₂Bis (3-triethoxysilylpropyl) tetrasulfide (TESPT) or formula [(C₂H₅O)₃Si (CH₂)₃S]₂Bis (3-triethoxysilylpropyl) disulfide (TESPD) is used. TESPD is commercially available, for example, from Degussa under the name Si266 or Si75 (in the latter case in the form of a mixture of disulfide (75% by weight) and polysulfide) or from Witco under the name Silquest A1589. TESPD is, for example, from Degussa under the name Si69 or Si75 (or X50S when supported on carbon black with a 50% content) or from Osi Specialties under the name Silquest A1289 (both, both). A commercially available mixture of polysulfides in which n is an average value of about 4) is commercially available. [0019] Those skilled in the art will use the content of the coupling agent in the compositions of the present invention as an application, the nature of the elastomer used, and, if applicable, as an auxiliary reinforcement filler. It can be adjusted by the amount of reinforced silicon carbide replenished by the inorganic filler of. In addition to the elastomer matrix, the tire tread composition of the present invention comprises the reinforcing filler and optionally one or more inorganic reinforcing filler / elastomer binders, other constituents and additives commonly used in rubber mixtures. For example, coating plasticizers, pigments, oxidation resistant agents, ozone wax resistant, sulfur and / or peroxides and / or bismaleimide-based cross-linking systems, cross-linking accelerators, extender oils, and optionally inorganic fillers. Contains all or part of one or more reagents for this purpose, such as alkoxysilanes, polyols, amines, etc. [0020] The tire tread of the present invention can be used to reduce the rolling resistance of the tire containing it and includes a crosslinked rubber composition as defined above. The tire of the present invention includes such a tread. The above-mentioned features of the present invention, as well as other features, are described below for some examples of the present invention, but not limited to, in comparison with the last example illustrating the prior art. It will be better understood by reading the description. In the examples, the properties of the compositions of the present invention were evaluated as follows. 1) Mooney Viscosity ML (1 + 4) (at 100 ° C): ASTM Measured by D-1646 (hereinafter abbreviated as ML). 2) (ME300) at 300%, (100%) at 100% and (ME10) modulus at 10%: Measured by ISO37. 3) Scott breaking index: measured at 20 ° C. 4) Breaking load (BL) is measured by MPa. 5) Elongation at break (EB) (%). 6) Hysteresis loss (HL): Measured by rebound at 60 ° C (%), the measured loss deformation is 40%. 7) Shore A hardness: Measured by DIN 53505. 8) Dynamic share characteristics (E'and ΔE', G^*And ΔG^*): At 10Hz, 0.15% to 50% for E', G^*Measured as a function of deformation performed with peak-to-peak deformation of 0.45% to 50%. The non-linearity displayed is the difference in shear modulus between 0.15% and 50% deformation (MPa). Hysteresis is represented by tanΔ at 23 ° C with a 7% deformation. Measured by ASTM D-2231-71 (revised in 1977). 9) Specificity of description for unfilled composition: In Example 3 for unfilled materials, the hysteresis description was the value of tanΔ, measured at 10 Hz with sinusoidal compression at temperatures 0 ° C and 50 ° C. .. [0021] [0021]<u style="single">Example 1</u><u style="single">The non-functionalized triblock IR / BR / IR copolymer according to the present invention and the rubber composition of the present invention containing the copolymer A.</u> 1)<u style="single">Preparation of the triblock copolymer A of the present invention and two "control" homopolymers</u> 1.1)<u style="single">Preparation of Copolymer A of the Present Invention</u>Contains 500 g of butadiene, along with 0.01 mol of 1,1', 4,4'-tetraphenyldilithiobutane (known to those of skill in the art as a bifunctional initiator), and 5,000 g of degassed toluene. Added to a liter of reactor. The polymerization was carried out at 70 ° C., and the monomer conversion rate after 1 hour was 100%. The contents were determined by weighing the extract dried at 110 ° C. under reduced pressure of 300 mmHg. The molecular weight of the resulting dilithiated polybutadiene (this molecular weight was determined by the osmotic method for samples stopped at 2 equivalents of lithium metanolate) was 95,000 g / mol. [0022] The osmotic method was performed on these samples with the "Osmomat 020" model osmotic meter marketed under the name "Gonotec". The intrinsic viscosity of this sample was 1.42 dl / g, and the proportion of vinyl structural units determined by the near infrared method was 16%. 50 g of isoprene (isoprene purified by passing through basic alumina and then distilled with azeotropic water by nitrogen bubbles) was added to the dilithiated polybutadiene. The isoprene conversion rate after 80 minutes at 40 ° C was 100%. By this method, a triblock IR / BR / IR copolymer was obtained. To this, 0.4 parts of 4,4'-methylene-bis-2,6-t-butylphenol was added per 100 parts of elastomer (phr) and treated with an oxidation resistant agent. The copolymer was recovered by a normal steam stripping operation and then dried on a roll device at 100 ° C. for 20 minutes. [0023] The intrinsic viscosity of this copolymer A was 1.5 dl / g, and the proportion of vinyl structural units of the isoprene moiety determined by proton NMR was 8%. Based on this molecular weight determined by the osmotic method and this NMR analysis, it can be concluded that the molecular weight of each IR block is 10,000 g / mol, which is consistent with the infused amount of isoprene and initiator. .. 1.2)<u style="single">Preparation of control homopolymer B consisting of polybutadiene</u>This polybutadiene B was prepared under the same conditions as the preparation of polybutadiene in 1.1), except that the initiator used for this polybutadiene B was not dilithiated. The initiator was n-butyllithium (hereafter n-BuLi), which was introduced into the reaction medium in an amount of 0.01 mol. The polybutadiene obtained from the polymerization reaction was treated with an oxidation resistant agent by adding 0.4 phr of 4,4'-methylene-bis-2,6-t-butylphenol. The molecular weight of the obtained polybutadiene B (this molecular weight was determined by the osmotic method) was 120,000 g / mol. The intrinsic viscosity of this polybutadiene B was 1.38 dl / g, and the proportion of vinyl structural units of the isoprene moiety determined by the near infrared method was 16%. [0024] 1.3)<u style="single">Preparation of control homopolymer C consisting of polyisoprene</u>This polyisoprene C was prepared by substituting isoprene for butadiene under the same conditions as in the synthesis of polybutadiene B 1.2). The polyisoprene obtained from the polymerization reaction was treated with an oxidation resistant agent by adding 4,4'-methylene-bis-2,6-t-butylphenol. The polyisoprene was recovered by a normal steam stripping operation and then dried on a roll device at 100 ° C. for 20 minutes. The molecular weight of the obtained polyisoprene C (this molecular weight was determined by the osmotic method) was 110,000 g / mol. The intrinsic viscosity of this polyisoprene C was 1.29 dl / g, and the proportion of 3,4-bonds in the isoprene moiety was 8%. [0025] 2)<u style="single">Comparison of the rubber composition of the present invention, each containing copolymer A, with a control "composition" based on the control homopolymers B and C.</u> 2.1)<u style="single">Rubber composition lacking reinforcing filler</u>The test is, 1) Composition A of the present invention based on the block copolymer A of the present invention, 2) A "control" composition B based on the polybutadiene B, and 3) A "control" composition C, based on a blend of the polybutadiene B and the polyisoprene C (the polyisoprene content of the blend is equal to the polyisoprene content of the copolymer A). I went about. The following composition (phr) was used for each of these three compositions A, B and C. Elastomer matrix 100 ZnO 2.5 Stearic acid 1.5 Sulfur 1.2 Sulfenamide (1) 1.2 Here, (1) represents N-cyclohexyl-2-benzothiazil sulfenamide. [0026] Each composition is prepared in a closed mixer by thermomechanical work at a paddle rate of 40 rpm at a paddle rate of 40 ° C until the same drop temperature of 90 ° C is achieved, in a process lasting 5 minutes, while the vulcanization system is 30 ° C. Introduced in C's "homo-finisher". Vulcanization was carried out at 150 ° C for 75 minutes. The results are shown in Table 1 below. [0027] [table 1]<u style="single">table 1</u><img file="JP5113970B2_D0001.tif" />From these results, the present invention based on IR / BR / IR triblock copolymer A within the range related to the measurement of tire rolling resistance, that is, for tanΔ in the range of 0 ° C to 50 ° C. It is concluded that the vanishing levels obtained with composition A of are always below those obtained with composition B or C based on polybutadiene B and a blend of polybutadiene B and polyisoprene C, respectively. As is clear from FIG. 1, the copolymer A of the composition A shows a non-separated phase for the three blocks containing it, whereas the blend of homopolymers B and C has a separated phase (phase separated). It is noted that it gives (may be concluded from the existence of a second group of peaks on the disappearance graph for the blends that are present). [0028] 2.2)<u style="single">Rubber composition for tire treads containing reinforced filler</u>The test was performed on three compositions A', B'and C', which in this case differ from the compositions A, B and C in 2.1) in that they each contain a strengthening filler consisting of carbon black N375. I was broken. More precisely, the respective compositions A', B', C'tested are: 1) 40phr (corresponding composition, hereinafter A'₁, B'₁And C'₁Identified by) 2) 60phr (corresponding composition, hereinafter A'₂, B'₂And C'₂Identified by) Includes the amount of any of the strengthening fillers in. The following composition (phr) was used for each of these three compositions A', B'and C'. Elastomer matrix 100 N375 40 or 60 ZnO 2.5 Stearic acid 1.5 Sulfur 1.2 Sulfenamide (1) 1.2 Here, (1) represents N-cyclohexyl-2-benzothiazil sulfenamide. Each composition is prepared in a closed mixer by thermomechanical work at a paddle rate of 40 rpm at a paddle rate of 40 ° C until the same drop temperature of 160 ° C is achieved, in a process lasting 5 minutes, while the vulcanization system is 30 ° C. Introduced in C's "homo-finisher". Vulcanization was carried out at 150 ° C for 30 minutes. The results are shown in Table 2 below. [0029] [Table 2]<u style="single">Table 2</u><img file="JP5113970B2_D0002.tif" />Regarding the properties in the vulcanized state, for these carbon black-filled compositions, the compositions of the present invention based on the Triblock IR / BR / IR copolymer, regardless of the filler content. A'₁And A'₂It is noted that the hysteresis at low deformations is significantly improved over polybutadiene B or other compositions based on a blend of polybutadiene B and polyisoprene C. Therefore, the composition A'of the present invention.₁And A'₂It is concluded that the rolling resistance of the tread containing the tread is improved with respect to that of the tire having the tread containing these "control" compositions in each case. [0030]<u style="single">Example 2</u><u style="single">The functionalized diblock SBR / IR copolymer of the present invention and the rubber composition of the present invention containing these copolymers.</u> 1)<u style="single">Preparation of functionalized diblock SBR / IR copolymer D and functionalized SBR "control" copolymer E of the present invention, these copolymers exhibit 90 ML.</u> 1.1)<u style="single">Preparation of block copolymer D of the present invention</u> 1.1.1)<u style="single">Preparation of living polyisoprene</u>Polyisoprene was continuously prepared in a 14 liter capacity reactor equipped with a turbine stirrer. The following components were continuously introduced into this reactor: cyclohexane and isoprene in a mass ratio of 100: 14.5, and a solution of 10,000 μmol of active sec-butyllithium (s-BuLi) per 100 g of isoprene. The flow rates of the various solutions were adjusted so that the average residence time was 40 minutes. The reaction temperature was maintained at 60 ° C. The monomer conversion was 100% at the reactor outlet. [0031] Residual butyllithium content is the reaction product obtained with benzophenone and is analyzed by gas phase chromatography (retention time 8 minutes 20 seconds) using the "HP 5800" chromatograph on the "CPSil 19" column. Determined from the sample by the reaction product to be produced. The residual BuLi content was measured to be 5% by this method. The number average molecular weight of the resulting living polyisoprene was 9,800 g / mol (this molecular weight was determined by osmometer measurement for samples stopped at 1 equivalent of lithium metalnolate). This osmotic pressure measurement was performed with a commercially available "Osmomat 090" model osmometer under the name "Gonotec". The glass transition temperature of this polyisoprene was -64 ° C, and the content of 3,4-bond was 8%. [0032] Lithiumized polyisoprene was stored in nitrogen at a temperature of 10 ° C. No changes in the contents were observed after several weeks of storage at this temperature under nitrogen pressure. 1.1.2)<u style="single">Copolymerization of butadiene and styrene initiated by this living polyisoprene</u>Cyclohexane, butadiene and styrene were introduced into the 14 liter reactor described above with their respective flow rates set to 100: 12.2: 2.3. 80 ppm (mass) of tetramethylethylenediamine was also added to this reactor. 200 μmol of n-BuLi was injected at the line inlet to neutralize the protonic impurities introduced by the various components present at the line inlet. 610 μmol per 100 g of the monomer of the living polyisoprene solution described in 1.1.1) was injected at the reactor inlet. Each flow rate was adjusted so that the average residence time in the reactor was 40 minutes. The temperature was maintained at 90 ° C. [0033] The conversion rate measured for the sample taken at the reactor outlet was 90%, while the intrinsic viscosity measured at 0.1 g / dl in toluene was 2.01 dl / l. A 300 μmol / 100 g monomer functionalizing agent consisting of dibutyl dichlorotin was then added to a dynamic mixer equipped with a stirrer set to a speed of 2,500 rpm containing the already obtained SBR / IR block copolymer. Four minutes after this coupling reaction, the copolymer functionalized by this method was subjected to 0.8 phr of 2,2'-methylene-bis (4-methyl-6-t-butylphenol) and 0.2 phr of N- (1,1). It was treated with an oxidation resistant agent with 3-dimethylbutyl) -N'-phenyl-p-phenylenediamine. [0034] The copolymers treated in this way were separated from the solution by steam stripping and then dried on a roll device at 100 ° C. for 20 minutes to give the functionalized SBR / IR block copolymer D of the present invention. The intrinsic viscosity of this copolymer D was 2.49 dl / g and the ML viscosity was 88. The SBR block of this copolymer D contained 16% (mass) of styrene and its butadiene portion had a vinyl structural group content of 24%. [0035] 1.2)<u style="single">Preparation of "control" copolymer E</u>This functionalized SBR-E contains styrene and butadiene, except that 610 μmol / 100 g of monomeric living polyisoprene was replaced with 630 μmol / 100 g of monomeric active n-BuLi to initiate this copolymerization. It was prepared by copolymerizing in a reactor started with n-BuLi by the method described in 1.1.2). The conversion at the reactor outlet was 98%, and the intrinsic viscosity of the obtained SBR was 1.82 dl / g before the addition of dibutyl dichlorotin. After coupling with dibutyldichlorotin, the SBR was subjected to the aforementioned antioxidant treatment and stripping and drying operations. The intrinsic viscosity of the obtained copolymer E was 2.34 dl / g, and its ML viscosity was 90. The microstructure of this copolymer E was the same as that of the SBR block of the copolymer D. [0036] 2)<u style="single">Preparation of functionalized diblock SBR / IR copolymer F and functionalized "control" SBR copolymer G of the present invention, these copolymers exhibit 70 ML.</u> 2.1)<u style="single">Preparation of block copolymer F of the present invention</u>This functionalized copolymer F has 1) the amount of living polyisoprene added to initiate the copolymerization is 700 μmol / 100 g of monomer in this case instead of 610 μmol of 1.1.2), and 2 ) It was prepared by carrying out the method disclosed in 1.1.2) for the above-mentioned Copolymer D, except that the amount of dibutyldichlorotin added was 350 μmol / 100 g of the monomer. The conversion at the reactor outlet was 99%, and the intrinsic viscosity of the obtained SBR / IR block copolymer was 1.74 dl / g before the addition of dibutyl dichlorotin. After coupling with dibutyldichlorotin, the resulting copolymer was subjected to the aforementioned oxidation resistant treatment and stripping and drying operations. The intrinsic viscosity of the obtained copolymer F was 2.16 dl / g, and its ML viscosity was 70. The microstructure of this copolymer F was the same as that of the SBR block of the copolymer D. [0037] 2.2)<u style="single">Preparation of "control" SBR copolymer G</u>This functionalized SBR-G contains styrene and butadiene, except that 610 μmol / 100 g of monomeric living polyisoprene was replaced with 720 μmol / 100 g of monomeric active n-BuLi to initiate this copolymerization. It was prepared by copolymerizing in a reactor started with n-BuLi by the method described in 1.1.2). The conversion at the reactor outlet was 97%, and the intrinsic viscosity of the obtained SBR was 1.71 dl / g before the addition of dibutyl dichlorotin. After coupling with dibutyldichlorotin, the SBR was subjected to the aforementioned antioxidant treatment and stripping and drying operations. The intrinsic viscosity of the obtained copolymer G was 2.12 dl / g, and its ML viscosity was 70. The microstructure of this copolymer G was the same as that of the SBR block of the copolymer D. [0038] 3)<u style="single">Comparison of rubber compositions of the invention with "control" compositions, each containing a functionalized diblock SBR / IR copolymer of the invention.</u> 3.1)<u style="single">Composition with carbon black based reinforced filler</u> 3.1.1)<u style="single">First series of compositions</u>The tests were performed on two rubber compositions, each containing 50 phr of carbon black N220. 1) Composition D₁: The composition of the present invention based on the functionalized copolymer D of the present invention. Has SBR / IR blocks, ML is 90, and 2) "Control" composition E₁: Based on the "control" SBR copolymer E, functionalized and has an ML of 90. Each composition D₁And E₁The composition of is as follows (phr). Elastomer 100 N220 50 ZnO 3 Stearic acid 2.5 Oxidizing agent (1) 1.5 Sulfur 1.5 Sulfenamide (2) 0.8 Here, (1) is N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine, and (2) is N-cyclohexyl-2-benzothiazil sulfenamide. [0039] Each composition D₁And E₁Is prepared in a closed mixer by thermomechanical work at a paddle speed of 40 rpm in a process lasting 5 minutes until the same drop temperature of 170 ° C is achieved, while the vulcanization system is a roll device at 30 ° C. Introduced in. Vulcanization was carried out at 150 ° C for 40 minutes. The results are shown in Table 3 below. [0040] [Table 3]<u style="single">Table 3</u><img file="JP5113970B2_D0003.tif" />Regarding the properties of these carbon black-filled compositions in a vulcanized state, the composition D of the present invention based on the functionalized SBR / IR block copolymer D.₁Hysteresis properties (at low and high levels of deformation) of the functionalized SBR-E based "control" composition E₁It is concluded that there will be improvements in those of them. Therefore, the composition D of the present invention₁The rolling resistance of a tire having a tread comprising the above-mentioned "control" composition E₁It is concluded that there is an improvement with respect to that of tires with treads that include. [0041] Furthermore, this composition D of the present invention₁Is the composition E₁Shows a lower ML viscosity than this conventional composition E₁Attention is paid to the point of achieving better workability. Therefore, when introduced into a rubber composition filled with carbon black, the copolymer D of the present invention is a conventionally known composition E.₁It is concluded that it provides improved hysteresis and workability. 3.1.2)<u style="single">Second series of compositions</u>The tests were performed on three rubber compositions, each containing 50 phr of carbon black N375. 1) Composition D₂: The composition of the present invention based on the functionalized copolymer D of the present invention. Has SBR / IR blocks and has an ML of 90, 2) "Control" composition E₂: Based on the "control" SBR copolymer E, functionalized, ML is 90, and 3) "Control" composition E'₂: Based on a blend of the "control" SBR copolymer E and the "control" polyisoprene C of Example 1. Each composition D₂, E₂And E'₂The composition of is as follows (phr). Elastomer 100 N375 50 ZnO 2.5 Stearic acid 1.5 Oxidizing agent (1) 1.5 Sulfur 1.2 Sulfenamide (2) 1.2 Here, (1) is N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine, and (2) is N-cyclohexyl-2-benzothiazil sulfenamide. [0042] Each composition D₂, E₂And E'₂Is prepared in a closed mixer by thermomechanical work at a paddle rate of 40 rpm in a process that lasts for 5 minutes until the same drop temperature of 160 ° C is achieved, while the vulcanization system is "uniform" at 30 ° C. Introduced in the "homo-finisher". Vulcanization was carried out at 150 ° C for 30 minutes. The results are shown in Table 4 below. [0043] [Table 4]<u style="single">Table 4</u><img file="JP5113970B2_D0004.tif" />Regarding the properties of these carbon black-filled compositions in a vulcanized state, the composition D of the present invention based on the functionalized SBR / IR block copolymer D.₂Hysteresis properties (at low and high levels of deformation) of the functionalized SBR-E based "control" composition E₂A "control" composition E'with respect to them and based on the blends described above.₂It is concluded that those of them will be improved. [0044] Therefore, the composition D of the present invention₂The rolling resistance of a tire having a tread comprising the above-mentioned "control" composition E₁And E'₂It is concluded that improvements will be made with respect to that of tires with treads in each case, including. Furthermore, this composition D of the present invention₂Is the composition E₂Shows a lower ML viscosity than this conventional composition E₂Achieved better workability with respect to, on the one hand, said composition E'₂Shows ML viscosity close to, composition E'₂It is noteworthy that it achieves workability comparable to that of. Therefore, when introduced into a rubber composition filled with carbon black, the copolymer D of the present invention₂Is a conventionally known composition E₂And E'₂It is concluded that it gives improved hysteresis and workability as a whole. [0045] 3.2)<u style="single">Composition with silica-based reinforced filler</u>The test was performed on two rubber compositions, each containing 50 phr of silica. 1) Composition F: The composition of the present invention based on the functionalized copolymer F of the present invention. Has SBR / IR blocks, ML is 70, and 2) "Control" composition G: Based on the "control" SBR copolymer G, functionalized with an ML of 70. The compositions of the respective compositions F and G are as follows (phr). Elastomer 100 Silica (1) 50 Binder (2) 10 ZnO 3 Stearic acid 2.5 Oxidizing agent (3) 2.5 Sulfur 1.5 Sulfenamide (4) 1.8 Here, (1) is a highly dispersible silica in the form of microbeads commercially available from Rhodia under the name of "Zeosil 1165 MP". (2) is a polysulfide organosilane commercially available from Degussa under the name "X50S". (3) is N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine, and (4) is N-cyclohexyl-2-benzothiazil sulfenamide. [0046] The respective compositions F and G were prepared according to the method described in EP-A-501227, ie, at 160 ° C., at an average paddle speed of 45 rpm, in two steps where thermomechanical work lasted 5 minutes and 4 minutes, respectively. It was prepared by a method performed until the same lowering temperature was achieved, while the vulcanization system was introduced in a roll device at 30 ° C. Vulcanization was carried out at 150 ° C for 40 minutes. The results are shown in Table 5 below. [0047] [Table 5]<u style="single">Table 5</u><img file="JP5113970B2_D0005.tif" />Regarding the properties of these silica-filled compositions in a vulcanized state, the hysteresis characteristics of the composition F of the present invention based on the functionalized SBR / IR block copolymer F (at low and high levels of deformation). Is improved with respect to those of the functionalized SBR-G based "control" composition G, and the processability of this composition F of the present invention is said to be the composition G (approximately the same ML value). It is concluded that it is substantially equal to that of. Therefore, it is concluded that the rolling resistance of a tire having a tread containing the composition F of the present invention is improved with respect to that of a tire having a tread containing the "control" composition G. [Simple explanation of drawings] FIG. 1 shows the development of tanΔ.