WO2009077837A1

WO2009077837A1 - A1,3-butadiene and styrene copolymer product, functionalized at the extremities of its polymeric chains, and the preparation process

Info

Publication number: WO2009077837A1
Application number: PCT/IB2008/003437
Authority: WO
Inventors: Luiz Fernando Nicolini; Clóvis Henriques DE LIRA; Carlos Roberto de Albuquerque Campos; Fernando Vasconcelos Figueiredo; Mauro Cresta De Barros Dolinsky; Neusa Maria Toccheto Pires; Monica De Almeida De Sant'anna
Original assignee: Petroflex Industria E Comercio S.A.
Priority date: 2007-12-14
Filing date: 2008-12-11
Publication date: 2009-06-25
Also published as: BRPI0705025A2

Abstract

This invention refers to a 1, 3 -butadiene and styrene copolymer product, functionalized at both extremities of its chains. This invention also refers to the preparation process of a 1, 3 -butadiene and styrene copolymer product, functionalized at both extremities of its polymeric chains. This invention further refers to compounds containing 1, 3 -butadiene and styrene copolymer product and use of the same.

Description

A 1,3 -BUTADIENE AND STYRENE COPOLYMER PRODUCT, FONCTIONALIZED AT THE EXTREMITIES OF ITS POLYMERIC CHAINS,

AND THE PREPARATION PROCESS

This invention refers to a 1, 3 -butadiene and styrene copolymer product, functionalized at both extremities of its chains. This invention also refers to the preparation process of a 1, 3 -butadiene and styrene copolymer product, functionalized at both extremities of its polymeric chains. This invention further refers to compounds containing 1, 3 -butadiene and styrene copolymer product and use of the same .

BACKGROUND OF THE INVENTION

Obtaining materials that are perfectly adaptable in their usage has been a constant challenge for science and technology in recent years. The growing demand for materials that have an appropriate balance of important and specific properties, added to the ecological restrictions of utilization, has produced great efforts from scientists in the search for innovative solutions to these challenges. The science of polymers has made a decisive contribution to this process. Due to intensive research and the use of sophisticated processes of polymerization, new products have been obtained, with a combination of properties that until now were not found in traditionally known materials. The emphasis with respect to the environment has guided this research and generated processes and products that are increasingly ecologically appropriate . Among the wide variety of polymers, the elastomers are the best known. Due to their large capacity to deform elastically when submitted to tension and then return spontaneously to their original form when the tension ceases, elastomers can be employed to obtain many important products when correctly used in the form of vulcanized compounds. The main products are tires in all their complexity, including their constituents such as tread, sidewalls etc, and mats, straps, and a wide range of technical products.

These rubbery or elastomeric products, in determinate applications, need to present a series of properties, which cannot always be combined simultaneously. In the case of tires for automobiles, the following properties are required; elasticity, low abrasion, good adhesion on different surfaces, low rolling resistance, as well as wet skid resistance, in low and high temperatures. Performance improvement in one of these properties normally results in a decrease in the performance in one of the others. This is equally undesirable and most of the time it becomes impossible to optimize all the properties.

Numerous solutions have been used by tire manufacturers, with the objective of combining and improving the different properties of their products. This has essentially consisted in the combined use of different elastomers, in the utilization of different reinforcement fillers, which interact physically and chemically with the elastomers, and in the use of compatible additives in the preparation of the vulcanized rubber compounds.

For example, tires manufactured with elastomers of the type SBR (copolymers 1, 3 -butadiene-styrene) , including those produced in cold emulsion polymerization (E- SBR) and those produced in solution polymerization (S-SBR) , with bound styrene of approximately 23%wt, present a high wet skid resistance, and also a high rolling resistance. The tires that are manufactured with conventional elastomers such as the 1,4-Cis BR (polybutadiene High Cis) , NR (Natural Rubber) and IR (Polyisoprene) , present low rolling resistance and low wet skid resistance (P. L.A. Coutinho, CH. Lira, L. F. Nicolini, A Ferreira; Elastomers for the "Green Tire" , 1^st Chemical and Petrochemical Industry Congress of Mercosur, Buenos Aires, Argentina, 1998) . The appropriate combination of these different elastomers, in vulcanized compounds, allows the production of tires with an improved balance of properties.

Moreover, the use of compatible additives, utilized in the preparation of vulcanized compounds, or even the use of modified elastomers in the polymeric structure, including the incorporation of specific functional groups, increases the miscibility between the different elastomers, as well as their interaction with the reinforcement fillers, which markedly improves the resulting properties of the tire.

As has been described in other researches, an increase in the content of the 1,2-vinylic units, in the polydienic sections of the elastomers of type S-SBR, results in an increase of its glass transition temperature

(Tg) , which provides an improvement in the skid resistance properties of the vulcanized compounds for tires (CH. Lira, L. F. Nicolini, G. Weinberg, N. M. T. Pires, P. L.A.

Coutinho - Elastomers For High Performance Tires -

Presented at a Meeting of the Rubber Division, American

Chemical Society, Cleveland, Paper N° 112, 2001) .

Moreover, it was demonstrated that a higher content of these units assists the solubility of the elastomers of type S-SBR in other elastomers, such as 1,4

Cis-BR and NR (R. H. Schuster, H. M. Issel and V. Peterseim

Selective Interactions in Elastomers; A Base for

Compatibility and Polymer-Filler Interactions; Rubber Chem. Technol., 69, 5, 1996) .

Therefore, any structural modification that can be incorporated into the different elastomers that assists the miscibility between them, besides providing an improved compatibility with the different reinforcement fillers employed in vulcanized elastomeric compounds, also improves the resulting properties of the tires.

There is a special interest in the tread, the part of the tire where the main mechanical forces are concentrated. This is where the properties of high wet/icy skid resistance and low rolling resistance are demanded.

Elastomeric compounds used in the production of tires, especially in the tread, are normally composed of copolymers, formed by a conjugated diene and a monomer with an aromatic vinyl structure.

Elastomers of type S-SBR are mainly used. These copolymers present a predominantly random distribution of their constituent mers along their polymeric chains and can also present sections with blocked distribution, or a mixture of random and blocked distribution. They are decisive in the obtainment of the final properties of the tire . In the documentation of patent EP 0929582 (US

6,013,718) and EP 1110998 (US 6,667,362 B2) , there is a description of the preparation and use of polydienes and copolymers resulting in the copolymerization between the conjugated dienes and a monomer with an aromatic vinyl structure (e.g.: S-SBR), which contains functional groups of siloxane and silanol in the end section of the polymeric chains. These groups interact with the silica used in the vulcanized compounds, improving its properties. The patents display the comparative results obtained from the use of these elastomers in several vulcanized elastomeric compounds .

Patent GB 2368069 describes the preparation process of the functionalized polymers in both extremities of the polymeric chains. Its structure is essentially that of a triblock, where the intermediary section can be a polydiene or a copolymer, resulting from the copolymerization between the conjugated diene and a monomer with an aromatic vinyl structure (e.g. : S-SBR) , where the end sections are preferentially polydialkylsiloxanes.

Patent EP 0849 333 B2 describes the use of substituted siloxanes in the preparation of the polydienes or copolymers, resulting from the copolymerization between the conjugated dienes and a monomer with an aromatic vinyl structure. The use of these functionalized polymers in vulcanized elastomeric compounds and their observed properties are also presented. Patent US 5,717,043 describes the preparation of polymers resulting from the copolymerization between conjugated dienes and a monomer with an aromatic vinyl structure (e.g.: S-SBR), functionalized with amine groups. These groups interact with the carbon black, utilized as a component of the vulcanized compounds, improving their properties. Furthermore, said patent describes the use of a polymerization initiator prepared "in situ", in the obtainment of these polymers and the properties of the resulting vulcanized compounds. The patent also describes the use of coupling agents in the preparation of these polymers .

Patent EP 0 992 536 Al describes the preparation of a polymer resulting from the anionic copolymerization between two conjugated dienes (e.g.: copolymer 1,3- butadiene- isoprene (S-IBR) . This patent describes the use of polar compounds for the control of the microstructure of these copolymers, and the properties observed in vulcanized compounds . The abovementioned examples are perfectly- illustrative of the state of the art, in the sense that many of these developments are still considered current. However, there is an increase in demand for higher performance materials and products arising from, for example, the increase in the power of automobiles and improved highway conditions.

Description of the Invention

The present invention concerns a product and a process of preparation of a new family of elastomers of type S-SBR, designed mainly for the production of high performance tires. The production of these elastomers uses advanced processes of polymerization, allowing larger control over the macrostructure and microstructure of the polymer.

The control over the polymeric architecture allows the obtainment of elastomers with an improved balance of mechanical properties and better suitability to their end use. The objective of this invention is the preparation of elastomers of type S-SBR (copolymers of 1,3- butadiene-styrene) , modified in their structure and functionalized at the extremity of their polymeric chains, and their preparation process. More specifically, this invention deals with the preparation of copolymers of type S-SBR, with a controlled macrostructure and microstructure, the introduction of functional groups at the end of the polymeric chains, and the use of these copolymers in vulcanized elastomeric compounds and their properties .

Although it is known that polydienes and/or copolymers, resulting from the copolymerization between conjugated dienes and a monomer with an aromatic vinyl structure, can be functionalized in their extremities, in the appropriate conditions, the effect of a structural change in the polymeric chains of these polymers, which includes the presence of terminal functional groups situated in both extremities of the polymeric chains, one of them preferentially being of the siloxane type, in the properties of the vulcanized elastomeric compounds, is not known in the state of the art .

The Product

The elastomers in this invention are copolymers of the type functionalized S-SBR, produced by the process of anionic polymerization in solution.

They are basically formed by a preferential composition between one or more conjugated dienes and one or more monomers with an aromatic vinyl structure, in appropriate proportions. They have a controlled macrostructure and microstructure, with an appropriate content of 1,2-vinylic units, based on the conjugated diene incorporated in the copolymer, and the specific functional groups in the polymeric structure.

These elastomers have a predominantly random distribution of their constituent mers, along the polymeric chains. At the end of these chains, in both extremities, there are specific functional groups that interact and/or react with the reinforcement fillers utilized in the vulcanized elastomeric compounds. Furthermore, their chains present linear structures or a composition of linear, branched and/or radial structures, with a controlled microstructure, and have a determinate content of 1,2-vinylic units, based on the conjugated diene incorporated in the copolymer. Elastomers containing linear, branched and radial polymeric chains are obtained, in the appropriate conditions. For this to happen, it is necessary to use coupling agents, such as silicon tetrachloride (SiCl₄) , tin tetrachloride (SnCl₄) and divinylbenzene (DVB) etc, in the preparation of these elastomers.

More specifically, these elastomers are copolymers obtained by the polymerization of one or more monomers of the conjugated diene type (e.g.: 1, 3 -butadiene) with one or more monomers with an aromatic vinyl structure (e.g.: styrene) , which present a predominantly random distribution of constituent mers in their polymeric chains, so that the microsequences of one of these mers are preferentially less than 10 units, mainly for the aromatic vinyl mers. Furthermore, their polymeric chains have a linear, branched or radial structure. They also present a controlled microstructure, with a content of 1,2-vinylic units between 8% and 80%, based on the total of the conjugated diene incorporated in the copolymer, and can also present different contents of 1,4-cis, and 1,4-trans units, as well as 3,4-vinyl, depending on the conjugated diene employed. The polymeric chains are functionalized at both the extremities with specific functional groups, which interact and/or react with the reinforcement fillers of the vulcanized elastomeric compounds. One of the extremities of the polymeric chains is functionalized preferentially with silyl, silanol and siloxane type groups, represented by the structures: -SiH₂(OH), -Si(Ri)₂(OH), -SiH(OH)₂, -SiRi(OH)₂, -Si(OH)₃, -Si(ORi)₃, -(SiRiR₂O)_x-R₃, -Si (R₃) ₃-_m(X) _m, where X is a halogen, x is the number of repetitive units between 1 and 500, m is the number of linked groups, varying from 0 to 3, Ri and R₂ are identical or different, and can be alkoxy or alkyl, linear or branched, cycloalkyl, aryl, alkylaryl, aralkyl or vinyl groups, in each case having 1 to 20 carbon atoms, and R₃ is H or alkyl, linear or branched, in each case having 1 to 20 carbon atoms, or a mononuclear aryl group, as well as siloxane groups that contain amine groups, represented by the formula -A¹-Si(A²- N( (H) _k (Ri)₂-Ic) )_y (ORi)₂ (R₃) ₃-(_y+z), where: k can vary from 0 to 2 , y can vary from 1 to 3 , and z can vary from 0 to 2 , 0 < y+z < 3, Ri and R₂ are identical or different, and can be alkyl, linear or branched, cycloalkyl, aryl, alkylaryl, aralkyl or vinyl groups, in each case having 1 to 20 carbon atoms, mononuclear aryl groups, R₃ is H or alkyl, linear or branched, in each case having 1 to 20 carbon atoms, or a mononuclear aryl group, and A¹ and A² are chains of up to 12 carbon atoms, linear or branched, preferentially alkyl, allyl or vinyl .

The other extremity of the polymeric chains of these elastomers is preferentially functionalized with groups of the type -OH, -COOH, -COX, where X as a halogen, -SH, -CSSH, -NCO, amine or epoxy. The amine groups can be represented by the following structures: -N(Ri)₂, -NRiR₂ - NHR₁, -NH₂, where Ri and R₂ are identical or different, can be alkyl, linear or branched, cycloalkyl, aryl, alkylaryl, aralkyl or vinyl groups, in each case having 1 to 20 carbon atoms .

For the elastomers of this invention, predominantly in one of the extremities of the polymeric chains, functional groups are used, preferentially of the amine type, represented by the structures -N(Ri)₂, -NR_xR₂, - NHRi, -NH₂, where R₁ and R₂ are identical or different, can be alkyl, linear or branched, cycloalkyl, aryl, alkylaryl, aralkyl or vinyl groups, in each case having 1 to 20 carbon atoms, and at the other extremity of the polymeric chains, functional groups preferentially of the siloxane type, in the form of structures that can be represented by the general formula -- [--Si (RiR₂) -0-] _n--Si (RiR₂) -OH, where Ri and R₂ are identical or different, and can be alkoxy or alkyl, linear or branched, cycloalkyl, aryl, alkylaryl, aralkyl or vinyl groups, in each case having 1 to 20 carbon atoms, and n represents the number of units of the siloxane functional group before a silanol terminal group. Polysiloxane sequences or blocks can also be incorporated and distributed along the polymeric chains although they are preferentially terminal .

Small sections or microsequences of one of the monomers of the copolymer, situated along the polymeric chains, can also form part of the structure of these elastomers .

More specifically, the elastomers of this invention present a percentage composition in weight of their chains, which can vary from 5% to 50%, , for the aromatic vinyl monomer (e.g.: styrene) , and from 50% to 95% for the conjugated diene (e.g.: 1, 3 -butadiene) . Preferentially, these elastomers present a composition from 15% to 40%, for the percentage in weight of the monomer with an aromatic vinyl structure, and from 60% to 85% for the percentage in weight of the conjugated diene incorporated in the copolymer.

They have a controlled microstructure, with a content of 1,2-vinylic units from 8% to 80%, in their chains, based on the conjugated diene incorporated in the copolymer. More preferentially, the content of the 1,2- vinylic units is found in the range from 10% to 70%, allowing its microstructure to present different contents of its 1,4-cis, and 1,4-trans units, as well as 3,4-vinyl units, depending on the conjugated diene employed in the copolymerization . Their polymeric chains preferentially present linear structures or a composition between linear, branched and/or radial structures .

Both extremities of their polymeric chains are functionalized, one of them preferentially with amine groups, and the other with siloxane groups, followed by silanol groups .

For the functionalization of one of the extremities of the polymeric chains, an amine is used, preferentially pyrrolidine. For the functionalization of the other extremity, a siloxane is used, preferentially hexamethylcyclotrisiloxane (D₃) , which allows the incorporation of continuous sequences of the siloxane functional group -- [--Si (CH₃) ₂-0-] --, and a silanol terminal group --Si(CH₃J₂-OH.

These elastomers have a Mooney Viscosity (Mll+4 @ 100⁰C) in a range from 30 to 90, and an average molecular weight in the range . from Mw=80,000 to 700,000, with a polydispersion in the range from 1.05 to 4.0, when analyzed by Size Exclusion Chromatography (SEC) , based on polystyrene standards.

These elastomers present glass transition temperatures, Tg, in the range from -92°C to -I⁰C₁ depending on the content of the aromatic vinyl monomer of the copolymer and the microstructure of the conjugated diene incorporated in the copolymer.

The elastomers of this invention are functionalized in both extremities of their polymeric chains, in one with amine groups, preferentially pyrrolidine, and in the other extremity with siloxane groups, preferentially with hexamethylcyclotrisiloxane (D₃) , which allows the incorporation of a sequence of siloxane groups - [--Si (CH₃) ₂-0--] -, which vary in the range from 1 to 500 units per polymeric chain, followed by the silanol termination (--Si(CH₃J₂-OH) .

A schematic representation of the structures of these elastomers is presented below.

A

G roup 1 F₁

G roup 2

₁ where, A represents the polymeric chains of a polymer, formed by the copolymerization between one or more conjugated dienes with one or more monomers with an aromatic vinyl structure (e.g.: S-SBR), which have a preferentially random distribution of their constituent mers, linear structure (group 1) , or a preferential composition of linear, branched and/or radial structures (group 2) , as well as a controlled content of 1,2-vinylic units, based on the incorporated conjugated diene; Fi represents a terminal functionalization of the polymeric chains, and can be groups of the type -OH, -COOH, -COX, where X is a halogen, -SH, -CSSH, -NCO, amine, and epoxy, the amine groups may be represented by the following structures -N(Rx)₂, -NRiR₂, -NHRi, -NH₂, where R₁ and R₂ are identical or different, can be alkyl, linear or branched, cycloalkyl, aryl, alkylaryl, aralkyl or vinyl groups, in each case having 1 to 20 carbon atoms;

F₂ represents one of the extremities of the polymeric chains, functionalized preferentially with silyl, silanol and siloxane type groups, represented by the structures: -SiH₂(OH), -Si(Ri)₂(OH), -SiH(OH)₂, -SiR_x(OH)₂, -Si(OH)₃, -Si(OR₁J₃, -(SiRiR₂O)_x-R₃, -Si (R₃) ₃-m(X)m, where X is a halogen, x is the number of repetitive units between 1 and 500, m is the number of linked groups, varying from 0 to 3 , Ri and R₂ are identical or different, and can be alkoxy or alkyl, linear or branched, cycloalkyl, aryl, alkylaryl, aralkyl or vinyl groups, in each case having 1 to 20 carbon atoms, and R₃ is H or alkyl, linear or branched, in each case having 1 to 20 carbon atoms, or a mononuclear aryl group, as well as siloxane groups that contain amine groups, represented by the formula -A¹-Si(A²- N( (H) _k(Ri) 2-k) )_y (ORi)₂ (R₃) 3- (y+z)/ where: k can vary from 0 to 2, y can vary from 1 to 3, and z can vary from 0 to 2, 0 < y+z < 3, Ri and R₂ are identical or different, and can be alkyl, linear or branched, cycloalkyl, aryl, alkylaryl, aralkyl or vinyl groups, in each case having 1 to 20 carbon atoms, mononuclear aryl groups, R₃ is H or alkyl, linear or branched, in each case having 1 to 20 carbon atoms, or a mononuclear aryl group, and A¹ and A² are chains of up to 12 carbon atoms, linear or branched, preferentially alkyl, allyl or vinyl; C is a coupling agent with functionality preferentially larger or equal to 2, represented by the structures Si(R)₂Xs, SiRX₃, SiHX₃, SiH₂X₂, SiX₄, Si(R)₂(OR)₂, SiR(OR)₃, Si(OR)₄, Sn(R)₂X₂, SnRX₃, SnHX₃, SnH₂X₂, SnX₄, etc, where R can be alkyl, linear or branched, cycloalkyl, aryl, alkylaryl, aralkyl or vinyl groups, in each case having 1 to 20 carbon atoms e X is a halogen; also structures such as R(R")_m where R can be alkyl, linear or branched, cycloalkyl, aryl, alkylaryl, aralkyl or vinyl groups, in each case having 1 to 20 carbon atoms, R" being a vinyl group and m is the number of units, varying in the range between 2 to 4 ;

More specifically, for the elastomers of this invention, A represents the polymeric chains of a polymer formed by the copolymerization of the monomers 1,3- butadiene and styrene, with a random distribution of their constituent mers, and a determinate content of the 1,2- vinylic structures, based on the content of the diene incorporated in the copolymer; Fi represents terminal amine groups, preferentially pyrrolidine; C represents the coupling agent employed in the preparation of elastomers, which has a functionality larger or equal to 2, being preferentially silicon tetrachloride (SiCl₄) or tin tetrachloride (SnCl₄) ; F₂ represents siloxane groups, preferentially hexamethylcyclotrisiloxane (D₃) , which allows the incorporation of a sequence of siloxane groups -[-- Si (CH₃) 2-0--] -, which vary in the range from 1 to 500 units per polymeric chain, followed by the silanol termination (- -Si(CH₃)₂-OH) .

The Production Process

For the production of these elastomers, it is necessary to employ a polymerization process that allows a refined control over the polymeric structure of the final product .

The anionic polymerization, and its characteristic of "live polymerization" , allows the obtainment of polymers with a controlled architecture . Due to their large versatility, varied polymeric structures can be obtained, allowing a large control over the microstructure and the macrostructure of the polymer, including the incorporation of functional groups in the polymeric chains . The use of this process requires a rigorous inspection of the employed materials to remove any impurities that could act as terminators and/or damage the control of the polymerization.

The elastomers cited in this invention are obtained by this process of polymerization, with the use of different reaction conditions and additives that aim to incorporate determinate characteristics in the final product . The process of polymerization of these elastomers can be conducted in a continuous manner or in batches .

However, the batch process is normally preferred since it provides a better control over the variables that affect the molecular architecture of the polymer.

The reactions of the polymerization, strictly speaking, are realized employing solvents, preferentially apolar, such as cyclohexane or n-hexane, although other solvents of the aliphatic class can also be utilized. Solvents of the aromatic class, such as toluene, can also be employed. However, their use is to be avoided since they negatively affect the kinetics of the reactions, they are more difficult to remove, and due to environmental restrictions. The initiator normally employed in these polymerizations is n-butyl-lithium although, in general, compounds of the group of alkyl-lithiums can also be employed. Examples of the alkyl groups of these initiators are: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec- butyl, t-butyl, n-amyl, sec-amyl, n-hexyl, sec-hexyl, n- heptyl, n-octyl, n-nonyl, n-dodecyl and octadecyl .

More specifically, the initiators are: n-butyl- lithium, sec-butyl-lithium, n-propyl-lithium, isobutyl- lithium, t-butyl-lithium and amyl-lithium. The monomers 1, 3 -butadiene and styrene are mainly used for the production of these elastomers, although other conjugated dienes and other vinyl-aromatic monomers can also be employed. Of the conjugated dienes, aside from 1,3- butadiene, there are: 2-alkyl-1, 3 -butadiene, 2,3-dialkyl- 1, 3 -butadiene, 2 -alkyl-3 -alkyl-1, 3 -butadiene, 1,3- pentadiene, 1, 3-hexadiene, 2,4-hexadiene, etc. Apart from styrene, other vinyl-aromatic monomers can also be employed, such as alpha-methyl-styrene, orto, meta and para divinylbenzene, orto, meta and para- methylstyrene, para-t-butyl-styrene, vinyl-toluene, methoxystyrene, vinylmesitylene, etc. For the control of the content of the 1,2-vinylic units of the diene incorporated in the copolymer, polar substances are utilized that act as Lewis bases, such as N, N, N" , lST-tetramethylethylenediamine (TMEDA) , tetrahydrofurane (THF) or ditetrahydrofurylpropane (DTHFP) . A wide range of ethers and amines can also be utilized, for example: dimethyl ether, diethyl ether, di-n-propyl ether, diisopropyl ether, di-n-butyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, trimethyl amine, triethyl amine, N-methyl morpholine, N-ethyl morpholine, N- phenyl morpholine, etc.

The terminal functionalization of these elastomers is introduced with the objective of improving the interaction of the polymeric chains with the reinforcement fillers in the vulcanized compounds. It is usually introduced utilizing a functionalized initiator, a functionalized terminator, or by the reaction between the active anionic terminals of the polymeric chains and the compounds that contain desirable functional groups.

A large variety of functionalizations can, in principle, be incorporated in these elastomers. It is preferable that these functionalizations be incorporated in the extremities of the polymeric chains.

For example, a functional group can be introduced via the utilization of a functionalized initiator, and the other by the utilization of a terminator, also functionalized, at the end of the polymeric chains.

For the elastomers of this invention, one of the functional groups of the polymeric chains should be preferentially of the siloxane type.

It is known that a large variety of compounds can be utilized for the functionalization of polymers, such as ethylene oxide, benzophenone , carbon dioxide, dialkylaminobenzaldehyde, carbon disulfide, alkoxysilanes, alkylphenoxysilanes, phenoxysilanes, etc.

Patents EP 396780 and EP 849333 provide examples of compounds and processes that can be employed with this purpose .

The terminal functional groups of the polymeric chains of the elastomers of this invention are preferentially of type -OH, -COOH, -COX, where X is a halogen, -SH, -CSSH, -NCO, amine, epoxy, silyl, silanol or siloxane, as well as the polysiloxane and siloxane groups or polysiloxane containing amine groups. Some of these groups can be better represented by the following structures:

• Amine groups: -N(Ri)₂, -NR₂R₂, -NHRi, -NH₂, where Ri and R₂ are identical or different, can be alkyl groups, linear or branched, cycloalkyl, aryl, alkylaryl, aralkyl or vinyl, in each case having from 1 to 20 carbon atoms ;

• Silyl, silanol and siloxane groups: SiH₂(OH), -Si(R₁J₂(OH), -SiH(OH)₂, -SiR₁(OH)₂, -Si(OH)₃,-- Si(ORi)₃, -(SiRiR₂O)_x-R₃, -Si (R₃) ₃-_m(X)_m, where X is a halogen, x is the number of repetitive units between 1 to 500, m is the number of replacement groups, and can vary from 0 to 3, Ri and R₂ are identical or different, and can be alkoxy or alkyl groups, linear or branched, cycloalkyl, aryl, alkylaryl, aralkyl or vinyl, in each case having from 1 to 20 carbon atoms, and R₃ is H or alkyl, branched or linear, in each case having from 1 to 20 carbon atoms, or a mononuclear aryl group; and

• Siloxane groups that contain amine groups, represented by the formula -A^Si (A²-N( (H) _k [R₁) ₂- _k) )_y(0Ri) _z (R₃) ₃-(_y+z) , where: k can vary from 0 to 2 , y can vary from 1 to 3 , and z can vary from 0 to 2 , 0 < y+z < 3, R₁ and R₂ are identical or different, and can be alkyl groups, linear or branched, cycloalkyl, aryl, alkylaryl, aralkyl or vinyl, in each case having from 1 to 20 carbon atoms, , aryl mononuclear groups, R₃ is H or alkyl, branched or linear, in each case having from 1 to 20 carbon atoms, or a mononuclear aryl group, and A¹ and A² are chains of up to 12 carbon atoms, linear or branched, preferentially alkyl , alyl or vinyl .

The elastomers of this invention are functionalized at the extremities of their polymeric chains, in one with amine groups, preferentially pyrrolidine, and in the other extremity with siloxane groups, preferentially with hexamethylcyclotrisiloxane

(D₃) . In the case of the amine groups, these elastomers present a functionalization of at least 70% of their polymeric chains. For the situation of the siloxane groups, the incorporation of a sequence of groups - [--Si (CH₃) ₂-0-- ] - is adopted, followed by a silanol termination (-- Si (CH₃) ₂-OH) , which varies in the range from 1 to 500 units per polymeric chain. As previously stated, these elastomers are obtained by the process of anionic polymerization in solution. The utilization of this polymerization process requires that all the materials employed are free from any impurities that may in any way prejudice the end result of the polymerization, such as humidity, chain transfer agents, etc.

This invention uses a method of polymerization divided into sequential steps, which allows a large control over the polymeric architecture. 1^st step: formation of the amine-functionalized initiator and copolymerization of the 1, 3-butadiene- styrene . In the first step, the random copolymerization is performed, in an appropriate reactor, involving the selected monomers. Normally a monomer with an aromatic vinyl structure (e.g.: styrene) and a conjugated diene (e.g.: 1, 3 -butadiene) are employed in the appropriate proportions. The percentage ratio in weight between these monomers varies in the range from 5% to 50% for the aromatic vinyl monomer and from 50% to 95% for the conjugated diene. More specifically, it adopts a content in the range from .15% to 40% in weight for the aromatic vinyl monomer, and in the range from 60% to 85% in weight for the conjugated diene, for these copolymers.

The copolymerization reaction is conducted in an appropriate apolar solvent, normally using cyclohexane or n-hexane.

The percentage ratio in weight monomers / solvent is controlled to ensure that the content of the total solids at the end of the reaction are found in the range from 8% to 30%. More specifically, it is employed in the range of total solids from 10% to 18%, and even more specifically, it is desirable that the content of the solids of these reactions is from 12% to 16%.

For the initiation of these reactions, organometallic compounds of lithium are employed. N-butyl- lithium is preferred as the initiator, due to its appropriate reactivity with the copolymerization 1,3- butadiene-styrene and its larger commercial availability. The quantity employed of this initiator is related to the total mass of the monomers employed in the reaction and the end molecular weight desired for the copolymer . For the functionalization of one of the extremities of the polymeric chains, pyrrolidine is used in the first step of the reaction. Due to its high reactivity, pyrrolidine reacts rapidly with n-butyl-lithium, even in the presence of the monomers, generating "in situ" a functionalized initiator of the type pyrrolidine-lithium, which initiates the copolymerization. (K. Morita, A. Nakayama, Y . Ozawa, N . Oshima, R . Fuj io and T . Fuj imaki , D . F. Lawson, J. R. Schreffler and T. A. Antkowiak - Anionic Polymerization of Dienes using Lithiumamide Initiator Prepared by in-situ Preparation; Polymer Preprints, 37 (2) , page 700, 1996) .

A polar additive is also used at this step of the copolymerization, which acts as a Lewis base, which is added to the reaction medium, before the start of the reaction. Its function is to increase the content of the 1,2-vinylic units of the polymeric chains.

These copolymers present a content of 1,2-vinylic units in the range from 8% to 80%, considering the total of the diene incorporated with the copolymer. It is desirable that the content of the 1,2- vinylic units be in the range from 10% to 70%. More specifically, a content of 1,2-vinylic units between 55 and 65% is preferred. This additive is not consumed during the copolymerization and the quantity utilized depends on an appropriate molar relation with the quantity of initiator employed. This relation is chosen to allow a better control of the kinetics of the reaction, as well as the microstructure of the diene incorporated with the copolymer .

The reaction of the copolymerization, strictly speaking, is achieved in the range of temperature between 25°C and 120⁰C. More specifically, the copolymerization is achieved between 30⁰C and 90⁰C. Even more specifically, the copolymerization is achieved between 30⁰C and 80⁰C, which is maintained until the total conversion of the monomers, which normally occurs between 30 and 55 minutes. The control of the temperature during this step is fundamental for the obtainment of the desired content of the 1,2- vinylic units, which vary depending on the temperature of the reaction. The pressure of the reactor during this step varies normally in the range from 3 Kgf/crn² to 5 Kgf/cm².

2nd step: reactions of the functionalization with siloxane (group 1) , or reactions of the partial coupling of the active polymeric chains, followed by the reactions of functionalization with siloxane of the remaining active chains (group 2) .

At this step of the reaction of the preparation of the elastomers, two synthesis routes can be adopted, depending on the desired molecular architecture for the elastomer . They are :

Route 1 : elastomer containing only linear polymeric chains . In the situation of an elastomer containing only linear polymeric chains, in the second step the compound is added that will functionalize the copolymer with the still active anionic chains, in the range of temperature between 60⁰C and 80⁰C, and the same range of pressure employed in the previous step.

Preferentially, hexamethylcyclotrisiloxane (D₃) is employed as the functionalizing agent. This cyclic compound allows, by the opening of its ring, the incorporation of the continuous sequences of the siloxane functional group (-- [--Si (CH₃) ₂-O-] --) .Once this step is concluded, which normally takes from 15 to 20 minutes, a terminator agent is added, maintaining the same previous reactionary conditions. Cetylic alcohol, or other alcohol with a high molecular weight, is employed as the terminator agent of the polymerization.

This final step is normally concluded in 10 minutes, with the deactivation of all the active anionic chains and the formation of the silanol terminal group - Si (CH₃) ₂-OH in the polymeric chains. The elastomer thus obtained has linear polymeric chains, which are functionalized with amine groups, in one of the extremities, and with siloxane groups, followed by silanol termination, in the other extremity. The elastomer is subsequently stabilized with the addition of an appropriate quantity of trynonylphenylphosphite and octadecyl 3, 5-di-t-butyl-4- hydroxyhydrocinnamate antioxidants . Route 2 : elastomer containing a preferential composition of linear, branched and/or radial polymeric chains .

In the situation of elastomers containing a preferential composition of linear, branched and/or radial polymeric chains, in the second step a coupling agent is added, with a functionality larger or equal to 2, which reacts with the active anionic chains, generating radial polymeric structures. This reaction is realized in the range of temperature between 55 ⁰C and 95 ⁰C, preferentially in the range of temperature between 65 ⁰C and 75 ⁰C, and the same range of pressure employed in the previous step.

The control of the efficiency of this coupling reaction is essential for the obtainment of an elastomer with an appropriate composition of linear and radial chains. The efficiency of this reaction is normally found in the range from 5% to 95%, preferentially in the range from 20% to 60%.

For the elastomers of this invention, silicon tetrachloride SiCl₄ is used preferentially as the coupling agent, which allows the coupling or union of up to four active chains per molecule. The partial coupling of the polymeric chains with SiCl₄, performed in this step, allows for a fraction of the original polymeric chains to remain active, making their functionalization possible.

Subsequently, the compound is added that will functionalize the remaining active chains, in the range of temperature between 60 °C and 80 ⁰C, and the same range of pressure employed in the previous step.

Preferentially, hexamethylcyclotrisiloxane (D₃) is employed as the functionalizing agent. This cyclic compound allows, by the opening of its ring, the incorporation of the continuous sequences of the siloxane functional group (-- [--Si (CH₃) ₂-O-] --) .

Once this step is concluded, which normally takes from 15 to 20 minutes, a terminator agent is added, maintaining the same previous reactionary conditions. Cetylic alcohol, or other alcohol with a high molecular weight, is employed as the terminator agent of the polymerization .

This final step is normally concluded in 10 minutes, with the deactivation of all the remaining active anionic chains and the formation of the silanol terminal group -Si(CH₃J₂-OH in the remaining active anionic chains.

The elastomer thus obtained has a preferential composition of linear and radial polymeric chains functionalized in their extremities. The linear chains are functionalized with amine groups, in one of the extremities, and with siloxane groups, followed by silanol termination, in the other extremity. The chains with a radial structure are only functionalized with amine groups in their extremities.

The elastomer is subsequently stabilized with the addition of an appropriate quantity of trynonylphenylphosphite and octadecyl 3, 5-di-t-butyl-4- hydroxyhydrocinnamate antioxidants .

Example 1 (Pi)

Preparation of an elastomer of type S-SBR, containing only linear polymeric chains, which have a random distribution of their constituent mers, functionalized in both their extremities, one with an amine group and the other with a siloxane group (--[-Si(CH₃J₂-O- ]--), followed by a silanol termination (--Si (CH₃) ₂-0H) , and a controlled microstructure. A schematic representation of the structure of this elastomer is presented below:

A Amine (S JR₁ R₂-O-J_nSiR₁ R₂O H

where, R₁ and R₂ = CH₃; n = n° of siloxane units.

In a 1000 liter capacity reactor, equipped with a turbine type mechanical agitator and a refrigeration cover, the first step was performed of the anionic copolymerization of the 1, 3 -butadiene monomers and styrene, in a solution of cyclohexane, with the polar additive TMEDA, and using n-butyl-lithium as the initiator. For this copolymerization, the reactor was filled with 61.3 Kg of 1, 3 -butadiene, 15.5 Kg of styrene, 470.6 Kg of cyclohexane and 0.2 Kg of TMEDA, 0.030 Kg of pyrrolidine, aiming for a content of total solids at the end of the reaction of 14% in weight.

For the initiation, a quantity of 0.045 Kg of n- butyl-lithium was used, which was necessary to neutralize any impurities still present in the materials being utilized and to initiate the copolymerization, strictly speaking. The n-butyl-lithium reacts preferentially with the pyrrolidine, generating a functionalized initiator with this amine. This new initiator, generated "in situ", is what properly initiates the copolymerization, functionalizing with an amine group at one of the extremities of the polymeric chains.

The copolymerization was conducted semi- adiabatically, with the temperature between 32⁰C and 76⁰C, until the total conversion of the monomers, which normally occurs in 55 minutes.

In a second step, 0.160 Kg of hexamethylcyclotrisiloxane (D₃) was added, which reacts with the active anionic terminals of the polymeric chains, forming a sequence of siloxane functional groups.

This step was conducted with the temperature between 65°C and 75°C, for a period of 15 to 20 minutes.

Finally, in a last step, 0.095 Kg of cetylic alcohol was added, to deactivate all the active anionic terminals, forming the silanol terminal group in the polymeric chains. This step took 10 minutes and was conducted with the temperature between 65⁰C and 75 °C. The elastomer obtained in this way, with linear polymeric chains functionalized with an amine group and siloxane groups followed by silanol, was subsequently stabilized with the addition of 0.3 Kg of the antioxidant trynonylphenylphosphite and 0.15 Kg of the antioxidant octadecyl 3 , 5-di-t-butyl-4-hydroxyhydrocinnamate .

The elastomer produced was recovered by the drying by evaporation of the solvent of the polymeric solution, in an open mill, heated to 100⁰C. The Mooney viscosity (Mll+4 @ 100⁰C) of the produced elastomer was 57. The total content of styrene in the copolymer was 20.9% and the content of the 1,2-vinylic units, based on the incorporated 1, 3 -butadiene, was 63.9%. Both these results were obtained using RMN ¹H spectroscopy. The molecular weight and the polydispersion of the elastomer were determined by Size Exclusion Chromatography, based on the standards of polystyrene, providing the values Mw=304.000 g/mol; Mn=270.000 g/mol and pd=1.12, respectively. The confirmation of the functionalization with siloxane groups in the elastomer was obtained via RMN ¹H spectroscopy, analyzing a sample of the elastomer submitted to a process of purification, in which a cycle of dissolution in cyclohexane followed by coagulation in ethanol and drying, was repeated 3 times, to remove any residual of the functionalizing agent not incorporated in the polymeric chains. The analysis was performed with the sample dissolved in CDCl₃ (deuterated chloroform) , without the use of TMS (tetramethylsilane) as a marker.

A spectrum of RMN ¹H characteristic of elastomer functionalized with siloxane, presented typical signs or bands of the hydrogen element of the methyl groups linked to the silicon element, in the region between 0 and 0.1 ppm.

The results of the RMN ¹H analysis, together with the results of the Size Exclusion Chromatography and the number of moles of the determined active initiator, allowed the obtainment of an average value for the length of the sequences of the siloxane functional group (-- [--Si (CH₃) ₂-

O-]--), including the silanol terminal group (--Si(CH₃)₂-

OH) , which were incorporated in the polymeric chains, which in this case corresponded to 5 units.

For the confirmation of the functionalization with amine groups, UV-VIS spectroscopy was used, analyzing a sample of the previously purified elastomer. The method is based on the interaction/reaction between the amine groups of the elastomer and the reagent "Patent Blue", forming an ammonium salt that can be observed in a wavelength of 628 nm.

This method requires the prior preparation of a calibration curve, which was obtained by the preparation of standards and of the respective UV-VIS spectroscopic analyses .

In Table 1, the results of the characterization of this elastomer are presented. Table 1

^(a) = based on the content of the diene incorporated in the copolymer.

Example 2 (P₂)

Preparation of an elastomer of type S-SBR, containing a composition of linear, branched and/or radial polymeric chains, which have a random distribution of their constituent mers, functionalized in both their extremities, one with an amine group and the other with a siloxane group (--[-Si(CH₃J₂-O-]--), followed by a silanol termination (-- Si(CH₃J₂-OH), and a controlled microstructure.

A schematic representation of the structure of this elastomer is presented below:

where, A = S-SBR; R₁ and R₂ = CH₃; n = n° of siloxane units; C = silicon

In a 1000 liter capacity reactor, equipped with a turbine type mechanical agitator and a refrigeration cover, the first step was performed of the anionic copolymerization of the 1, 3 -butadiene monomers and styrene, in a solution of cyclohexane, with the polar additive TMEDA, and using n-butyl-lithium as the initiator.

For this copolymerization, the reactor was filled with 61.3 Kg of 1, 3 -butadiene, 15.5 Kg of styrene, 471 Kg of cyclohexane and 0.35 Kg of TMEDA and 0.050 Kg of pyrrolidine

For the initiation, a quantity of 0.060 Kg of n- butyl-lithium was used, which was necessary to neutralize any impurities still present in the materials being utilized and to initiate the copolymerization, strictly speaking. The n-butyl-lithium reacts preferentially with the pyrrolidine, generating a functionalized initiator with this amine. This new initiator, generated "in situ", is what effectively initiates the copolymerization, functionalizing with an amine group at one of the extremities of the polymeric chains. The copolymerization was conducted semi- adiabatically, with the temperature between 30°C and 72⁰C, until the total conversion of the monomers, which normally occurs in 55 minutes. The pressure of the reactor varied in the range from 3 Kgf/cm² to 5 Kgf/cm² in this step.

In a second step, 0.0087 Kg of silicon tetrachloride was added, for the coupling of 30% of the active polymeric chains. This step was conducted with the temperature between 65⁰C and 75⁰C for a period of 5 minutes, in the same range of pressure as the previous step.

In the following step, 0.195 Kg of hexamethylcyclotrisiloxane (D₃) was added, which reacts with the anionic terminals of the remaining active chains, forming a sequence of siloxane functional groups. This third step was conducted with the temperature between 65⁰C and 75⁰C, for a period of 15 to 20 minutes.

Finally, in a last step, 0.120 Kg of cetylic alcohol was added, to deactivate all the still active anionic chains, forming the silanol terminal group. This final step took 10 minutes and was conducted with the temperature between 65⁰C and 75⁰C.

The elastomer obtained in this way, with linear and radial polymeric chains, functionalized with an amine group and siloxane groups followed by silanol, was subsequently stabilized with the addition of 0.30 Kg of the antioxidant trynonylphenylphosphite and 0.15 Kg of the antioxidant octadecyl 3, 5-di-t-butyl-4- hydroxyhydrocinnamate .

The elastomer produced in this way was recovered by the drying by evaporation of the solvent of the polymeric solution, in an open mill, heated to 100⁰C.

The Mooney viscosity (Mll+4 @ 100⁰C) of the produced elastomer was 59.7. The total content of styrene in the copolymer was 21.4% and the content of the 1,2- vinylic units, based on the incorporated 1, 3 -butadiene, was 64.2%. Both these results were obtained using RMN ¹H spectroscopy.

The molecular weight and the polydispersion of the elastomer were determined by Size Exclusion

Chromatography, based on the standards of polystyrene, providing the values Mw=510.000 g/mol; Mn=278.000 g/mol and pd=1.8, respectively.

To obtain the characterization results of this elastomer, the same procedures and analytical methods used in example 1 were adopted. In Table 2, the results of the characterization of this elastomer are presented.

Table 2

^(a) = based on the content of the diene incorporated in the copolymer.

A more complete characterization of the two elastomers described in examples 1 and 2 is presented in Table 3.

Table 3

NA = not applicable ;

DSC = Differential Scanning Calorimetry . SEC = Size Exclusion Chromatography PS = polystyrene

^(a) = based on the content of the diene incorporated in the copolymer . Example 3

Compound studies were carried out comprising SBR 1 (as comparison) and a SBR 2 according to the invention .

SBR 1 : SBR 1 is a solution polymerized SBR comprising uncoupled polymer molecules which are substituted with amino groups at one polymer chain end and coupled polymer molecules which carry amino groups at each chain end. Vinyl content : 66 weight-% Styrene content : 20 weight-% Mooney-viscosity (ML1+4 ) : 40 SBR 2 :

SBR 2 is a SBR according to the invention which consists of uncoupled polymer molecules which carry amino groups at one polymer chain end as well as Si-OH groups at the other chain end and coupled polymer molecules which carry amino groups at each chain end.

Vinyl content: 66 weight-%

Styrene content: 20 weight-%

Mooney-viscosity (ML1+4) : 54

The components listed in Table 4, except for sulphur, accelerator and sulfonamide, were mixed in a 1,5 L kneader at 150⁰C in a two-stage mixing procedure. The components sulphur, accelerator and sulfonamide were added in a following step on a mill at 40⁰C.

Table 4: Compound components (in parts per 100 parts of rubber)

The compounds were vulcanized for 20 minutes at 160⁰C after the mixing procedure. The physical properties of the vulcanizates are listed in Table 5.

Table 5: Vulcanizate properties

A low rolling resistance is advantageous for tires. A low rolling resistance can be expected from measurements done at the vulcanizate when the rebound at 60⁰C is high and the tan δ value at 60⁰C (from dynamic damping experiment) as well as the tan δ maximum (from the amplitude sweep measurement) are low. As can be seen in Table 5 that the vulcanizate from example V2 has a high rebound at 60⁰C as well as a low tan δ value at 60⁰C (from dynamic damping experiment) and a low tan δ maximum (from the amplitude sweep measurement) .

For tires also a high wet grip is necessary. From measurements done at the vulcanizate a high wet grip can be expected if the tan δ value at 0⁰C (from dynamic damping experiment) is high. It can be seen in Table 5 that the vulcanizate from example V2 has a high tan δ value at 0⁰C.

Claims

1. A 1, 3 -butadiene and styrene copolymer product, functionalized at the extremities of its polymeric chains, characterized by the fact that it includes the following formula :

A

G roup 1 F₁

G roup 2

where, A represents the polymeric chains of a polymer, formed by the copolymerization between one or more conjugated dienes with one or more monomers with an aromatic vinyl structure, which have a preferentially random distribution of their constituent mers, linear structure (group 1) , or a preferential composition of linear, branched and/or radial structures (group 2) , as well as a controlled content of 1,2-vinylic units, based on the incorporated conjugated diene;

Fi represents a terminal functionalization of the polymeric chains, and can be groups of the type -OH, - COOH, -COX, where X is a halogen, -SH, -CSSH, -NCO, amine, and epoxy; the amine groups may be represented by the following structures: -N(Ri)₂, -NR₂R₂, -NHR₁, -NH₂, where Ri and R2 are identical or different, can be alkyl groups, linear or branched, cycloalkyl, aryl, alkylaryl, aralkyl or vinyl, in each case having from 1 to 20 carbon atoms; F₂ represents one of the extremities of the polymeric chains, functionalized preferentially with silyl, silanol and siloxane type groups, represented by the structures: -SiH₂(OH), -Si(Ri)₂(OH), -SiH(OH)₂, -SiRi(OH)₂, -Si(OH)₃, -Si(ORJ₃, -(SiR₁R₂O)_x-R₃, -Si (R₃) ₃-_m(X) _m, where X is a halogen, x is the number of repetitive units between 1 and 500, m is the number of linked groups, varying from 0 to 3, Ri and R₂ are identical or different, and can be alkoxy or alkyl, linear or branched, cycloalkyl, aryl, alkylaryl, aralkyl or vinyl groups, in each case having 1 to 20 carbon atoms, and R₃ is H or alkyl, linear or branched, in each case having 1 to 20 carbon atoms, or a mononuclear aryl group, as well as siloxane groups that contain amine groups, represented by the formula -A¹-Si(A²- N( (H) _k (Ri) 2-k) )_y (ORi)₂ (R₃) ₃- _(y+z), where: k can vary from 0 to 2, y can vary from 1 to 3 , and z can vary from 0 to 2 , 0 < y+z < 3, Ri and R₂ are identical or different, and can be alkyl, linear or branched, cycloalkyl, aryl, alkylaryl, aralkyl or vinyl groups, in each case having 1 to 20 carbon atoms, mononuclear aryl groups, R₃ is H or alkyl, linear or branched, in each case having 1 to 20 carbon atoms, or a mononuclear aryl group, and A¹ and A² are chains of up to 12 carbon atoms, linear or branched, preferentially alkyl, allyl or vinyl; C is a coupling agent with functionality preferentially larger or equal to 2, represented by the structures Si(R)₂X₂, SiRX₃, SiHX₃, SiX₄, Si(R)₂(OR)₂, SiR(OR)₃, Si(OR)₄, Sn(R)₂X₂, SnRX₃, SnHX₃, SnX₄, etc, where R can be alkyl, linear or branched, cycloalkyl, aryl, alkylaryl, aralkyl or vinyl groups, in each case having 1 to 20 carbon atoms e X is a halogen; also structures such as R(R")_m where R can be alkyl, linear or branched, cycloalkyl, aryl, alkylaryl, aralkyl or vinyl groups, in each case having 1 to 20 carbon atoms, R" is a vinyl group and m is the number of units, varying in the range between 2 to 4.

2. The product of claim 1, characterized by the fact that A represents the polymeric chains of a polymer formed by the copolymerization of the monomers 1,

3- butadiene and styrene, with a random distribution of their constituent mers, and a determinate content of the 1,2- vinylic structures, based on the content of the diene incorporated in the copolymer; Fi represents terminal amine groups, preferentially pyrrolidine;

F₂ represents siloxane groups, preferentially hexamethylcyclotrisiloxane (D₃) , which allows the incorporation of a sequence of siloxane groups -[-- Si(CH₃J₂-O--]-, which vary in the range from 1 to 500 units per polymeric chain, followed by the silanol termination (- -Si(CH₃J₂-OH) , and C represents the coupling agent employed in the preparation of elastomers, which has a functionality- larger or equal to 2, being preferentially silicon tetrachloride (SiCl₄) or stannic tetrachloride (SnCl₄) ; 3. The product of claim 1, characterized by the fact that it includes copolymers that present a predominantly random distribution of their constituent mers in their polymeric chains, so that the microsequences of one of these mers are preferentially less than 10 units especially for the mers with aromatic vinyl structure.

4. The product of claim 1, characterized by the fact that the polymeric chains have a linear, branched or radial structure, with a controlled microstructure and a content of 1,2-vinylic units between 8% and 80%, based on the total of the conjugated diene incorporated in the copolymer, and can also present different contents of 1,4- cis, and 1,4 -trans units, as well as 3, 4 -vinyl, depending on the conjugated diene employed.

5. The product of claim 1, characterized by the fact that the polysiloxane sequences or blocks are optionally incorporated and distributed along the polymeric chains in a preferentially terminal position.

6. The product of claim 1, characterized by the fact that it presents a percentage composition, in weight, of their polymeric chains, which can vary in the range from 5% to 50%, more preferably from 15% to 40% for the aromatic vinyl monomer, and in the range from 50% to 95%, more preferably from 60% to 85% for the conjugated diene.

7. The product of claim 1, characterized by the fact that it has a controlled microstructure, with a content of 1,2-vinylic units in the range from 8% to 80%, more preferably from 10% to 70% in its chains, based on the conjugated diene incorporated in the copolymer.

8. The product of claim 1, characterized by the fact that it includes a Mooney Viscosity (Mll+4 @ 100⁰C) in a range from 30 to 90; an average molecular weight in the range from Mw=80,000 to 700,000, with a polydispersion in the range from 1.05 to 4.0, based on polystyrene standards; and glass transition temperatures, Tg, in the range from - 92°C to -1°C.

9. The product of claim 1, characterized by the fact that it includes an elastomer with the following formula:

A

Group 1 Am ine (SiR₁R₂-O-J_nSiR₁R₂OH where, A=S-SSBR, R₁ and R₂ = CH₃; n=n° of siloxane units.

10. The product of claim 1, characterized by the fact that includes an elastomer with the following formula:

Amine (SiR₁R₂-O-)_nSiR₁R₂OH

Group 2

where, A=S-SBR; R₁ and R₂ = CH₃; n = n° of siloxane units;

C = silicon.

11. A process of preparation of an elastomer product of 1 , 3 -butadiene and styrene functionalized in the extremities of its polymeric chains, characterized by the fact that it includes the following steps :

• 1^st step: formation of the amine- functionalized initiator and copolymerization of the 1,3- butadiene-styrene; • 2^nd step: reactions of the functionalization with siloxane (group 1) , or reactions of the partial coupling of the active polymeric chains, followed by the reactions of functionalization with siloxane of the remaining active chains (group 2) .

12. The process of claim 11, characterized by the fact that in the copolymerization step, the percentage ratio in weight between a monomer with an aromatic vinyl structure and a conjugated diene, varies from 5% to 50%, more preferably from 15% to 40%, for the aromatic vinyl monomer, and from 50% to 95%, more preferably from 60% to

85%, in weight, for the conjugated diene.

13. The process of claim 11, characterized by the fact that in the copolymerization step, the percentage ratio in weight of the monomers / solvent is such that the content of the total solids at the end of the reaction is found in the range from 8% to 30%, preferably from 10% to

18% and more preferably from 12% to 16%.

14. The process of claim 11, characterized by the fact that the copolymerization step includes a content of the 1,2-vinylic units in the range from 8% to 80%, preferably from 10% to 70% and more preferably from 55% and 65%, considering the total of the diene incorporated in the copolymer .

15. The process of claim 11, characterized by the fact that in the copolymerization step, the temperature of the reaction varies between 25⁰C and 120⁰C, preferably between 30⁰C and 90⁰C and more preferably between 30⁰C and 80⁰C.

16. The process of claim 11, characterized by the fact that in the copolymerization step, the time of the reaction includes a period of between 30 and 55 minutes and the pressure of the reactor during this step varies in the range from 3 Kgf/cm² to 5 Kgf/cm².

17. The process of claim 11, characterized by the fact that the functionalization reaction in the 2^nd step includes two possible routes: • Route 1 : elastomer containing only linear polymeric chains; and

• Route 2 : elastomer containing a preferential composition of linear, branched and/or radial polymeric chains .

18. The process of claim 17, characterized by the fact that Route 1 includes the addition of a compound to functionalize the copolymer of the still active anionic chains, in the range of temperature between 60⁰C and 80⁰C, and in the same range of pressure employed in the previous step .

19. The process of claim 17, characterized by the fact that the time of the reaction of the functionalization of the active polymeric chains in Route 1 varies between 15 and 20 minutes.

20. The process of claim 17, characterized by the fact that Route 2 includes the addition of a coupling agent, with functionality larger or equal to 2, with a reaction temperature in the range from 55⁰C to 95⁰C.

21. The process of claim 20, characterized by the fact that the reaction temperature of the coupling is in a range from 65⁰C to 75⁰C, and the pressure of the reaction is in a range from 3 Kgf/cm² to 5 Kgf/cm².

22. The process of claim 17, characterized by the fact that the efficiency of the coupling reaction in Route 2 varies between 5% and 95%, preferably from 20% to 60%.

23. The process of claim 17, characterized by the fact that the remaining active polymeric chains, after the partial coupling reaction, are functionalized by the addition of a compound, in the range of temperature between 60⁰C and 80⁰C, and in the same range of pressure employed in the previous step .

24. A compound, characterized by containing 1,3- butadiene and styrene copolymer product according to one or more of claims 1-10 and one or more fillers, dyes, pigments, softeners, reinforcing agents, rubber auxiliaries and/or crosslinking agents.

25. Use of the 1, 3 -butadiene and styrene copolymer product according to one or more of claims 1-10, characterized by being for the production of tires and of tire components.