EP4077409A1

EP4077409A1 - Modified diene polymer and method for the preparation thereof

Info

Publication number: EP4077409A1
Application number: EP19956445.1A
Authority: EP
Inventors: Liliia Andreevna BOIKO; Tatiana Aleksandrovna IARTSEVA
Original assignee: Sibur Holding PJSC
Current assignee: Sibur Holding PJSC
Priority date: 2019-12-20
Filing date: 2019-12-20
Publication date: 2022-10-26
Also published as: WO2021126001A1; WO2021126001A9; CN114929755A; KR20220120620A; EP4077409A4

Abstract

The present invention relates to a method for the preparation of a modified polydiene, the method comprising the following steps of i) preparing a catalyst complex including (A) a lanthanide compound, (B) a conjugated diene, (C) an organoaluminum compound, and (D) a halogen-containing component; ii) polymerizing a conjugated diene in an organic solvent medium in the presence of the catalyst complex obtained in step i); iii) on reaching at least 96% conversion of the monomer, introducing a modifying agent into the polymer, wherein the modifying agent is a low molecular weight polybutadiene containing terminal alkoxysilane groups; iv) terminating the polymerizate obtained in step iii), introducing an antioxidant and recovering the polymer.The technical result is the obtainment of the polydiene with improved processability and filler distribution in the polymeric matrix, wherein rubber compositions based thereon are notable for increased abrasion resistance of rubber mixtures (the volume loss due to the Shopper-Schlobach abrasion, mm³).

Description

MODIFIED DIENE POLYMER AND METHOD FOR THE PREPARATION

THEREOF

Field of the invention

The present invention relates to the synthetic rubber industry, in particular to the production of polymers for the manufacture of tires and other rubber products. In particular, the present invention relates to diene polymers which are modified by a low molecular weight polybutadiene containing terminal alkoxysilane group, and a method for the production thereof.

The technical result includes preparation of a polydiene having improved processability and filler distribution in a polymeric matrix, wherein rubber composition based thereon are notable for increased abrasion resistance of rubber compositions (Shopper-Schlobach abrasion volume loss, mm³). Furthermore, the modified diene polymer obtained according to the invention is characterized by a Mooney viscosity of from 40 to 50 Mooney unit, content of high molecular weight fraction (HMF 1 million a.m.u.) of not more than 3.5 wt.% and a branching index, characterized by mechanical loss tangent tg5 (1200%) (measured by the thermo gravimetry method in accordance with ASTM El 131, ISO 11358), from 4.0 to 6.0, and also the polydispersity index from 2.1 -2.5 wt.% and the content of 1 ,4-cis units of more than 96 wt.%.

Prior art

It is known that the use of 1,4-cis-polybutadiene allows to obtain rubber compositions having a low hysteresis losses value and high durability. However, these rubbers are characterized by poor processability due to high viscosity of obtained polymerizate. Prior art discloses methods of using liquid/low molecular weight rubbers as additives at a stage of rubber mixing to improve the processability of polybutadiene rubber compositions.

Patent application GB964931A (OLIVER WALLIS BURKE, July 29, 1964) discloses polymer blends and a method of the production thereof, namely it is proposed to use a liquid diene polymers and/or vulcanizates thereof, in admixture with 1,4- polybutadiene, obtained by the solution polymerization on a metallocene catalyst system at the stage of rubber mixing to improve its processability. In accordance with the method, the diene polymerization is carried out in the presence of organolithium compounds as a catalyst. However, data on properties of the obtained rubber compositions are not presented in the application, besides the microstructure of the resulting rubber contains cis-isomers in an amount of less than 96%, which results in the increase in the abrasion capacity of rubbers.

The use of liquid diene polymers as components of rubber compositions is widely known. Patent EP2082899 (CONTINENTAL AG (DE), May 18, 2011) describes a method for producing a rubber compound, the formulation of which comprises 5-50 wt. parts of a liquid low viscosity polymer. The resulting mixture exhibits the improved elasticity at low temperatures while improving tensile modulus at the 300% elongation.

It is shown in the inventors certificate SU1028681A (YAROSLAVSKIJ POLT INST (SU), July 15, 1983 ) that the use of low molecular weight epoxidized cis- polybutadiene in the formulation of the rubber compound based on SBR(synthetic butadiene rubber) makes it possible to significantly increase the fatigue endurance during stretching of rubbers.

Application US5430095 A (KURARAY CO (JP), July 4, 1995) discloses a process for use low molecular weight diene polymers, in particular, isoprene ones, produced using a lithium-containing catalyst with functional hydroxy- or amino groups, as additives for improving properties of rubber compositions, namely the processability and distribution of filler, namely carbon black. In accordance with the document, the introduction of low molecular weight polymers as additives at the stage of rubber mixing helps to improve the processability of rubber compositions, increases the fatigue endurance while stretching rubbers. However, the selected method of introduction does not result in the improvement of properties of the main polymer, and an increase in a dosage of low molecular weight diene polymers during rubber mixing results in deterioration of physical and mechanical characteristics.

Patent US6437205B1 (BRIDGESTONE CORP (JP), August 20, 2002) describes the use of a mixture of low molecular weight and high molecular weight polybutadienes obtained using neodymium catalyst system, as a rubber composition for use in a tire tread. In accordance with the method, the obtained rubber compositions are characterized by good grip with wet and icy roads, high rolling resistance and also good physical and mechanical properties, particularly, tensile stress at break and elasticity modulus.

However, these polybutadiene are taken in a ratio of 50:50, which results in rise in the cost of the final product due to the high cost of low molecular weight polymers. The resulting polymer blends have a low content of 1 ,4-cis units, namely 90%, which entails the high abrasion of the rubber compositions. The closest in respect to the essence to the present invention is a process for the preparation of polybutadienes disclosed in patent US7112632 (POLIMERI EUROPA SPA (IT), September 26, 2006). In accordance with the process, the process for the preparation of polybutadiene includes: (a) polymerisation of the butadiene; (b) treatment of the polymer solution obtained upon completion of stage (a) with a coupling agent selected from: (i) unsaturated natural oils; (ii) butadiene and/or isoprene oligomers; (iii) butadiene and/or isoprene copolymers with vinylarene monomers; the unsaturations present in compounds (i)-(iii) being at least partially substituted with groups selected from epoxides, anhydrides and esters; (c) recovery of the low branch content polybutadiene obtained upon completion of stage (b). In accordance with the patent, low branch content polymers are obtained.

It is known that branched polymers are used to achieve good processability of rubber compositions. The patent does not contain information on the degree of distribution of the filler in the polymer matrix, as well as on improving the abrasion and processability of the obtained polymer.

Disclosure of the Invention

It is an object of the present invention to improve processability and technological effectiveness of polydiene polymers, to improve the filler distribution in the polymer matrix and the abrasion resistance of rubber compositions based on these polydiene polymers.

To achieve the above object, the present invention provides a method for the preparation of a modified polydiene, comprising the following steps of: i) preparing a catalyst complex including (A) a lanthanide compound, (B) a conjugated diene, (C) an organoaluminum compound, and (D) a halogen-containing component; ii) polymerizing a conjugated diene in an organic solvent medium in the presence of the catalyst complex obtained in step i); iii) on reaching at least 96% conversion of the monomer, adding a modifying agent into the polymer, wherein the modifying agent is a low molecular weight polybutadiene containing terminal alkoxysilane groups; iv) terminating the polymerizate obtained in step iii), introducing an antioxidant and recovering the polymer. The technical result includes preparation of the polydiene with improved processability and filler distribution in the polymeric matrix, wherein rubber compositions based thereon are notable for increased abrasion resistance of rubber mixtures (Shopper-Schlobach abrasion volume loss, mm³).

The modified diene polymer obtained according to the invention is characterized by a Mooney viscosity of from 40 to 50 Mooney units, an amount of high molecular weight fraction (HMF 1 million a.m.u.) of not more than 3.5 wt.% and a branching index, characterized by mechanical loss tangent tg5 (1200%) (measured by the thermogravimetry method in accordance with ASTM El 131, ISO 11358), from 4.0 to 6.0, and also the polydispersity index from 2.1-2.5 wt.% and the content of 1,4-cis units of more than 96 wt.%.

It is known that the decrease in the Mooney viscosity of a rubber compound results in the reduction in energy consumption when rubbers are mixed with ingredients, in better calendaring and extrusion of rubber compositions, and in lowering temperatures at all steps of their processing, which reduces the likelihood of premature vulcanization. Furthermore, the decrease of viscosity of the rubber compound allows to increase the content of fillers in the mixture, thereby reducing its cost. (J.S. Shashok, A.V. Kaspyarovich, E.P. Uss. "Principles of compounding formulation of elastomeric compositions" (in Russian), 2013. - 98 p.)

Another important index is the Payne effect reflecting the presence of bonds and the intensity of the interaction between the filler particles in rubber compositions. It is known that the quality of rubbers directly depends on the degree of filler dispersion in the rubber matrix, which, in turn, defines the time of the manufacture of the rubber composition. It is rather difficult to achieve the high degree of filler dispersion, one method of solving the problem is the proposed introduction into the diene polymer of low molecular weight polybutadienes containing terminal alkoxysilane groups, due to which strong chemical bonds with the filler are created, as evidenced by the low values of the Payne effect.

In accordance with the present invention, low molecular weight polybutadienes comprising terminal alkoxysilane groups are represented by the general formula (1): wherein R is a hydrocarbon radical representing a linear or branched Ci-Cio alkyl, preferably C1-C4 alkyl, n is an integer from 1 to 3.

In accordance with the present invention, the low molecular weight polybutadiene with a molecular weight of from 1500 to 50000 g/mol is used. The increase in the molecular weight results in the increase in the dynamic viscosity (MPa*s) of the modifier, wherein there is the limitation in the solubility of the polymer, which complicates its introduction at the modification step. Characteristics of the used, commercially available low-molecular polybutadienes comprising terminal alkoxysilane groups are presented in Table 1.

In accordance with the present invention, a method for the preparation of modified diene polymers comprises several steps, namely: preparing a catalyst complex, polymerizing a diene with the use of the aforesaid complex, introducing a modifying agent when the conjugated diene conversion is equal to 96% and more is achieved.

The catalyst complex used in the method according to the invention includes a lanthanide-containing compound, an organoaluminum compound and a halogen- containing component. Lanthanide-containing compounds include at least one lanthanide atom: neodymium, lanthanum, cerium, praseodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. It is preferable to use neodymium compounds.

Lanthanide-containing compounds are, but are not limited to: carboxylates, organophosphates (in particular, alkylphosphates and arylphosphates), organophosphonates (in particular, alkylphosphonates and arylphosphonate) organophosphinates (in particular, alkylphosphinate and arylphosphinate), carbamates, dithiocarbamates, xanthogenates, b-diketonates, halogenides, oxyhalogenides, lanthanide alcoholates or mixtures thereof. Lanthanide carboxylates include formate, acetate, acrylate, methacrylate, valerate, gluconate, citrate, fumarate, lactate, maleate, oxalate, 2-ethylhexanoate, neodecanoate, naphthenate, stearate, oleate, benzoate, and picolinate.

Lanthanide organophosphates are dibutylphosphate, diphenylphosphate, dihexylphosphate, diheptylphosphate, dioctylphosphate, bis(l-methylheptyl) phosphate, bis(2-ethylhexyl)phosphate, didecylphosphate, didodecylphosphate, neodymium, bis(n- nonylphenyl)phosphate, butyl(2-ethylhexyl)phosphate, trisfdibutylphosphate] , tris[dipentylphosphate], tris[dioctylphosphate], tris[bis(2-ethylhexyl)phosphate], tris[bis(l-methylheptyl)phosphate], tris[bis(p-nonylphenyl) phosphate], tris[butyl(2- ethylhexyl)phosphate], tris[(l-methylheptyl)(2-ethylhexyl) phosphate], and tris[(2- ethylhexyl)(p-nony lphenyl)phosphate] . Organophosphonates include butylphosphonate, pentylphosphonate, hexylphosphonate, heptylphosphonate, octylphosphonate, (1- methylheptyl)phosphonate, (2-ethylhexyl)phosphonate, decylphosphonate, dodecylphosphonate, octadecylphosphonate, oleylphosphonate, phenylphosphonate, (n- nonylphenyl)phosphonate, butyl(butylphosphonate), pentyl (pentylphosphonate), hexyl(hexylphosphonate), heptyl(heptylphosphonate), octyl(octylphosphonate), (1- methylheptyl)((l-methylheptyl)phosphonate), (2-ethylhexyl)((2- ethylhexyl)phosphonate), decyl(decylphosphonate), dodecyl(dodecylphosphonate), octadecyl(octadecylphosphonate), oleyl(oleylphosphonate), phenyl(phenylphosphonate), (n-nonylphenyl)((n- nonylphenyl)phosphonate), butyl((2- ethylhexyl)phosphonate), (2-ethylhexyl)(butylphosphonate), (l-methylheptyl)((2- ethylhexyl)phosphonate), (2-ethylhexyl)((l -methylheptyl)phosphonate), (2- ethylhexyl)((n-nonylphenyl) phosphonate), and (p-nonylphenyl)((2- ethylhexy l)phosphonate) .

Organophosphinates include butylphosphinate, pentylphosphinate, neodymium hexylphosphinate, heptylphosphinate, octylphosphinate, (l-methylheptyl)phosphinate, (2-ethylhexyl)phosphinate, decylphosphinate, dodecylphosphinate, octadecylphosphinate, oleylphosphinate, phenylphosphinate, (n- nonylphenyl)phosphinate, dibutylphosphinate, dipentylphosphinate, dihexylphosphinate, diheptylphosphinate, dioctylphosphinate, bis(l- methylheptyl)phosphinate, bis(2-ethylhexyl)phosphinate, tris [bis(2-ethylhexyl) phosphate], didecylphosphinate, didodecylphosphinate, dioctadecylphosphinate, dioleylphosphinate, diphenylphosphinate, bis(n-nonylphenyl)phosphinate, butyl(2- ethylhexyl)phosphinate, (l-methylheptyl)(2-ethylhexyl)phosphinate, and (2-ethylhexyl) (n-nonylphenyl)phosphinate.

It is preferable to use carboxylates, neodymium organophosphates; the most preferable - neodymium neodecanoate, neodymium tris[bis-(2-ethylhexyl)phosphate], or mixtures thereof due to their faster and more complete alkylation, which increases the activity of the catalyst complex.

In the present invention a conjugated diene includes 1,3 -butadiene, isoprene,

2.3-dimethyl- 1,3-butadiene, piperylene, 2-methyl-3-ethyl- 1,3-butadiene, 3-methyl-l,3- pentadiene, 2-methyl-3 -ethyl- 1,3 -pentadiene, 3-methyl- 1,3-pentadiene, 1,3-hexadiene, 2-methyl- 1,3-hexadiene, 1,3-heptadiene, 3-methyl- 1,3-heptadiene, 1,3-octadiene, 3- butyl-l,3-octadiene, 3, 4-dimethyl- 1,3-hexadiene, 4, 5-diethyl- 1,3-octadiene, phenyl-1, 3- butadiene, 2, 3 -diethyl- 1,3 -butadiene, 2, 3-di-n-propyl-l, 3-butadiene, 2-methyl-3- isopropyl- 1,3-butadiene are used as the conjugated diene. It is the most preferable to use

1.3-butadiene and isoprene. The introduction of a conjugated diene is not the obligatory step for the preparation of a catalyst complex, however the presence thereof in the future substantially increases the activity of the catalyst.

Trialkylaluminum, triphenylaluminum or dialkylaluminum hydrides, alkylaluminum dihydrides, in particular trimethylaluminum, triethylaluminum, tri-n- propylaluminum, triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tritertbutylaluminum, triphenylaluminum, trihexylaluminum, tricyclohexylaluminum, trioctylaluminum, diethylaluminum hydride, di-n-propylaluminum hydride, di-n- butylaluminum hydride, diisobutylaluminum hydride, dihexylaluminum hydride, diisohexylaluminum hydride, dioctylaluminum hydride, diisoactylaluminum hydride, phenylethylaluminum hydride, phenyl-n-propylaluminum hydride, phenylisopropylaluminum hydride, phenyl-n-butylaluminum hydride, phenylisobutylaluminum hydride, benzylethylaluminum hydride, benzyl-n- butylaluminum hydride, benzylisobutylaluminum hydride, benzylisopropylaluminum hydride etc are used as the organoaluminum compound that is the alkylating agent.

It is preferable to use aluminum alkyls, alkyl aluminum hydrides or mixtures thereof. Most preferably, triethylaluminum, triisobutylaluminum, diisobutylaluminum hydride or mixtures thereof are used.

As the halogen-containing component within catalyst complex is it possible to use aluminum or tin organohalogen compounds such as dimethylaluminum chloride, diethylaluminum chloride, diisobutylaluminum chloride, dimethylaluminum bromide, diethylaluminum bromide, diisobutylaluminum bromide, dimethylaluminum fluoride, diethylaluminum fluoride, diisobutylaluminum fluoride, dimethylaluminum iodide, diethylaluminum iodide, diisobutylaluminum iodide, methylaluminum dichloride, ethylaluminum dichloride, methylaluminum dibromide, ethylaluminum dibromide, methylaluminum difluoride, ethylaluminum difluoride, methylaluminum sesquichloride, ethylaluminum sesquichloride, isobutylaluminum sesquichloride or mixtures thereof, and also trimethyltin chloride, trimethyltin bromide, triethyltin chloride, triethyltin bromide, di-tert-butyltin dichloride, di-tert-butyltin dibromide, dibutyltin dichloride, dibutyltin dibromide, tributyltin chloride and tributyltin bromide and the like, or mixtures thereof.

It is preferably to use ethylaluminumsesquichloride, ethylaluminum dichloride, diethylaluminum chloride or mixtures thereof as the halogen-containing component.

In accordance with the proposed method, a polymerization solvent is an inert organic solvent, which may be used alone or in mixtures with other aliphatic hydrocarbons, in particular such as butane, pentane, hexane, heptane; alicyclic hydrocarbons, namely cyclopentane, cyclohexane; monoolefins such as 1 -butene, 2- butene, or mixtures thereof; aromatic hydrocarbons, in particular, such as benzene, toluene, and xylene.

It is most preferable to use as the solvent as a hydrocarbon solvent that is a mixture of cyclohexane :hexane or cyclohexane efras (industrial hexane-heptane fraction of paraffinic hydrocarbons, dearomatized catalytic reforming gasolines with boiling point temperatures (65-75°C) in the ratio (30-55)÷(70-45)).

In accordance with the present invention, a catalyst complex is used to carry out the polymerization, the catalyst complex including (A) a lanthanide compound, (B) a conjugated diene, (C) an organoaluminum compound, and (D) a halogen-containing component, which are taken in a molar ratio of (A):( B):(C):(D) that is equal to 1:(5- 30):(8-30):(l.5-3.0), wherein the number of moles of (A) - the lanthanide compound - is taken based on moles of lanthanide, and the number of moles of (D) - the halogen- containing component - is taken based on halogen moles.

The preferable molar ratio of the components of the catalyst complex (A):(B):(C):(D) = l:(5-20):(8-20):(l.8-2.8).

The most preferable molar ratio of components of the catalyst complex (A):(B):(C):(D) = l:(10-15):(10-15):(2.1-2.5). The preparation of the modified diene polymer is carried out by a periodical or continuous method in a hydrocarbon solvent medium. The process consists in feeding a hydrocarbon charge consisting of a monomer and a solvent and a catalyst complex premixed with the solvent, said complex includes of a lanthanide compound, a conjugated diene, an organoaluminum compound and a halogen-containing component , preferably a halogen-containing organic compound, into the polymerization vessel (reactor/autoclave). The concentration of the monomer in the solvent, as a rule, is 7-12 wt.%, the preferable concentration is 9-10%. The concentration below 7% reduces the energy efficiency of the process, the increase in the monomer concentration of more than 12% increases the viscosity of the polymer solution, which results in difficulties during the transportation, spraying, agglomeration, the further processing, etc., results in high energy consumption while the isolation and drying of rubber. The process of preparing the catalyst complex (CC) consists in the introduction into the solution of a lanthanide compound of (most preferably neodecanoate or tris[bis(2-ethylhexyl)neodymium phosphate), a conjugated diene (most preferably 1,3- butadiene) in an aliphatic solvent, an organoaluminum compound (most preferably - triisobutylaluminum, triethylaluminum, diisobutylaluminum hydride or a mixture thereof), the resulting mixture is aged for 1 to 20 hours at a temperature of 23 ± 2°C, followed by the addition of a halogen-containing component (the most preferably - ethylaluminum sesquichloride, ethylaluminum dichloride, diethylaluminum chloride or mixtures thereof) and further maturing the catalyst at a temperature of from 0 to 100°C, preferably from 20 to 50°C. While the temperature decreases below 0°C, the incomplete maturation of CC is possible, while the temperature increases up to more than 50°C, the decrease in the catalytic activity and/or the increase in the ratio of the average molecular weight (Mw) to number-average molecular weight (Mn) - the polydispersity coefficient is possible. The increase in the latter will negatively affect the final properties of rubber products, in particular, wear resistance. The maturing time is from 1 minute to several days, in the future the decrease in the CC activity is possible.

The polymerization time is from 1 hour to 3 hours. On reaching the monomer conversion of at least 96 %, a modifying agent that is a low molecular weight polybutadiene containing terminal alkoxysilane groups is administered into the polymer. The modifying agent is used as a solution in an aliphatic or aromatic solvent. A solution of a branching agent is prepared in advance or immediately before use.

The molar ratio of the modifier based on the lanthanide is (0.01 -5): 1, i.e. it is acceptable to use from 0.01 to 5 moles of the modifier per 1 mole of the lanthanide. The ratio allows to produce the diene polymer with a high content of 1,4-cis units - more than 96 wt.%, an amount of high molecular weight fraction (HMF) is not more than 3.5 wt.% and branching index, characterized by the mechanical loss tangent tg5 (1200%) in the range of 4.0-6.0. The increase in the molar content of the modifier results in too highly branching of the polymer chain, which is undesirable, because the in this case the gelation increases and the elastic hysteresis properties deteriorate. The preferable modifienlanthanide molar ratio is (0.2-5): 1, and the most preferably is (0.4-1): 1. In case of use in an amount of less than 0.01 to the lanthanide, the claimed improved properties of the polymer are not achieved: the resulting rubber has a linear structure; the fact is known that branched polymers are processed better than linear ones. The feeding of the modifying agent in an amount of more than 5 moles to 1 mole of the lanthanide not only results in the increase in the cost of the final product, but also in the intense cross- linking of the polymer, which may adversely affect the plasto-elastic properties, thus there are problems with the isolation of the polymer and its processing.

Functional alkoxysilane groups react with a reactive terminal fragment of the diene polymer. The modification process is carried out for from 15 minutes to 5 hours, the most preferably from 20 minutes to 2 hours, at a temperature of 60-90°C. The temperature decrease will result in the increase in the polymer viscosity; correspondingly it will be difficult to isolate and process it, and the rate of "overgrowing" of the equipment will increase. At the same time, the increase in the indicated maximal modification temperature may result in the loss of activity of the terminal groups of the polymer chain, as a result of which the degree of polymer modification will decrease, i.e. the content of the residual modifier will increase.

At the end of the modification process, the polymerizate is stopped with softened water, or with ethyl or isopropyl alcohol, is stabilized with an antioxidant solution taken in an amount of 0.2-0.6 wt.%. Next, the rubber is isolated by known methods, such as steam-vapor degassing and roller drying.

The resulting polymer has a Mooney viscosity of from 40 to 50 Mooney units after the modification, the increase of this index above 50 Mooney units may provoke the deterioration in manufacturability during processing, lowering the index below 40 units results in the increase in cold flow, which results in problems during transportation and storage of the polymer (polymer briquettes “flow”, lose their shape, stick to the package). The polydispersity coefficient of the modified diene polymers is the most preferably from 2.1 to 2.5, the content of 1,4-cis units is more than 96 wt.%. The increase in the molecular weight distribution, as well as reduction in the mass fraction of 1,4-cis units can result in the deterioration of the mechanical characteristics and wear resistance. The content of the HMF of not more than 3.5 wt.% is the most preferable, since the increase of the index can result in the gelation of the polymer.

The present invention also relates to rubber compositions. The formulation of the components of the rubber compound is defined by the purpose, operating conditions and technical requirements for the product, production technology and other aspects. The production technology of rubbers includes mixing rubber with ingredients in special mixers or on rollers, scission and cutting semi-finished products from the rubber (shapes and sizes depend on the planned future use of the obtained rubber, in particular, on the planned test method) and vulcanization of the obtained semi-finished products in special devices (presses, autoclaves, shaper-vulcanizers, etc.).

The rubber compositions comprising the obtained diene polymers are prepared according to standard formulations (ASTM D3189 formulation, Table 3) and are characterized by the improved processability that is evidenced by the low Mooney viscosity of the rubber mixture, as well as the improved filler distribution in the rubber (the Payne effect).

Embodiment of the invention

Next, embodiments of the present invention will be described. It is necessary o clarify that it is not limited only to the presented examples and the same effect may be achieved using other embodiments, which do not go beyond the essence of the claimed invention. The description of test methods used to estimate the properties of the polymers produced by the claimed method.

1. The percentage of the conversion is determined by the gravimetric method based on isolating a polymer from the reaction medium by precipitating the polymer with ethyl alcohol from a polymerizate, drying the isolated polymer, calculating the polymer mass fraction in the polymerizate and directly calculating the conversion by calculating the ratio of the polymer mass fraction in the polymerizate to the mass fraction of the charge in the solvent.

2. The microstructure of the polymer chains was determined by IR spectroscopy according to a proprietary technique using the MDTIR (the multiple disturbed total internal reflection) attachment with a ZnSe crystal. The method is based on the registration of the IR spectrum of the sample to be analyzed on an infrared Fourier spectrometer using the MDTIR (the multiple disturbed total internal reflection) attachment and the further measurement of the maxima of optical densities of the analytical absorption bands: for 1 ,4-cis units at 740 cm ¹; for 1,4- trans units at 967 cm \ for 1,2 units at 910 cm ¹ The calibration of the IR spectrometer has been carried out according to industry standard samples of the polybutadiene microstructure, in which the mass fraction of isomeric units is determined by *H and ¹³C NMR spectra.

3. Molecular weight characteristics of rubbers were determined by gel permeation chromatography according to a proprietary technique using gel chromatograph "Breeze" of the firm "Waters" with refractometric detector. Rubber samples were dissolved in freshly distilled tetrahydrofuran, the mass concentration of the polymer in the solution was 2 mg/ml, the universal calibration according to polystyrene standards. The calculation was carried out using the Mark-Kuhn-Houwink constant for the diene polymer (K = 0.000457, a = 0.693). Conditions of the determination:

- a bank of 4 high-resolution columns (300 mm in length, 7.8 mm in diameter) filled with styrene gel, HR3, HR4, HR5, HR6, which allows to analyze polymers with a molecular weight of from 500 to 1x10⁷ a.m.u.; - a solvent is tetrahydrofuran, the flow rate is 1 cm³/min;

- the temperature of the thermostat of columns and refractometer is 30°C.

4. The Mooney viscosity of rubbers and rubber compositions (ML 1+4 at 100°C) was determined according to ASTM D 1646-07 on the Mooney MV2000 viscometer.

5. The elastic constituent of complex dynamic shear modulus G' (kPa) allowing to estimate the filler distribution in rubber mixtures and silanization of the filler was measured on the rubber processability analyzer RPA-2000 of the firm "Alpha Technologies" at 0.1 Hz and 100°C in the range of deformations from 1 to 450%. The difference between the accumulation moduli at the deformation amplitude of 1% and 50% - AG '= (G' 1 % - G'43%) - the Payne effect.

6. The scuff resistance on a renewable surface was evaluated according to State Standard 23509 (method B) on the ABRASION CHECK "Gibitre Instruments" abraser.

7. The branching index (the mechanical loss tangent tg5 (1200%)) was determined on the rubber processability analyzer RPA-2000 of the firm "Alpha

Technologies": the change of tg d was evaluated at a variable amplitude shift: the amplitude range is from 0 to 1200%, frequency is 0.1 Hz, temperature is 100°C.

Example I (prototype)

The polymerization of butadiene (BD) was carried out in a hydrocarbon solvent in the presence of a catalyst complex prepared on the basis of neodymium (Nd) versatate, followed by the addition of an alkylating agent, namely diisobutylaluminum hydride (DIBAH) and a halogen donor, namely diethylaluminum chloride (DEAC), neodymium versatate (NdV3) at a dosage of 2.8 mmol Nd per 1 kg of BD, DIBAH is in an 8-fold molar excess over Nd, DEAC is in a 3-fold molar excess. The polymerization was carried out in a reactor with a volume of 20 liters, equipped with a mixing device and a jacket for heat removal. The polymerization process lasted 90 minutes. Upon the completion of the polymerization 2 liters of the polymer were extracted from the reactor, the monomer conversion was 98%. A phenolic antioxidant 0.06 wt.% (Irganox 1520) was added to the selected aliquot. The solvent was removed, milled at a temperature of 80°C. Molecular weight characteristics (MWC) by GPC and branching index expressed as the mechanical loss tangent tg6 (1200%) was determined in the selected aliquot. The linear polymer having a Mooney viscosity of 35 Mooney units is obtained. A solution of maleinized polybutadiene Ricon 130 MA 8 in a mixture of hexanes (the solution concentration is 0.15 mol/1) at a dosage of 1.2 moles per 1 mole of Nd was fed into the residual polymerizate in the reactor at a temperature of 90°C. After 10 minutes, primary (Irganox 565) and secondary (TNPP) antioxidants were added, and the resulting modified polymer was unloaded. The modified polymer had a Mooney viscosity of 43 Mooney units and branching index tg6 1200% = 5.567, i.e. the branched polymer was obtained (Table 1). The polymer was also tested in the content of the rubber compound according to the ASTM 3189 formulation (Table 3), the test results are shown in Table 4.

Example 2 (comparative, the modifier is not added)

2.3 g (1.4 mmol) of the neodymium neodecanoate salt with a concentration of 8.9% as a solution in hexane, 40 ml of an aliphatic solvent were placed into a Schlenk flask having 250 ml in volume, it was stirred using a magnetic stirrer for 10 minutes at 23 °C. Then 3.6 g of butadiene (BD) in the form of a solution with a concentration of 22.4 wt.% was introduced into the flask. The molar ratio of BD/Nd = 10.

After 15 minutes of stirring at 23°C, 12.2 ml of DIBAH solution with a concentration of 1.18 mol/1 was fed into the flask and it was stirred for 30 min. The molar ratio of DIBAH/Nd=10. Then 5.8 ml of EASC solution in a concentration of 0.73 mol/L was introduced, the molar ratio of Cl/Nd = 3.0. Then, a solvent was introduced into the complex to reach the solution volume of 100 ml, it was stirred for 10 minutes and kept for the formation at 20-23 °C for 20 hours.

The polymerization is carried out in a reactor of 10 L in volume equipped with a stirrer and a jacket for heat removal. The temperature of the polymerization reaction was 95-100°C. The duration of the process is 2 hours.

While 96% monomer conversion is reached, a stopper was fed, a phenolic antioxidant was added; the degassing and roller drying were performed. Properties of the obtained polymer are presented in Table 2. The sample was also tested according to the formulation of rubber compositions ASTM 3189 (Table 3), the test results are shown in Table 4.

Example 3

It is analogous to example 2, but with the difference that, while achieving 96% monomer conversion, a modifier - a low molecular weight polybutadiene Polyvest EP- ST-E 60 having a molecular weight of 3200 g/mol and comprising terminal triethoxysilane groups was fed to the polymerizate. The low molecular weight polybutadiene is administered in a molar ratio of 0.6 to the neodymium in the form of a solution in nefras.

Properties of the obtained polymer are presented in Table 2. The sample was also tested according to the formulation of rubber compositions ASTM 3189 (Table 3), the test results are shown in Table 4.

Example 4 It is analogous to example 2, but with the difference that diethylaluminum chloride (DEAC) was used as a chlorinating agent in the formulation of the catalyst complex, the molar ratio of Cl/Nd was 2.5. The low molecular weight polybutadiene used as a modifying agent was administered in a molar ratio of 0.2 to the neodymium.

Example 5

It is analogous to example 3, but with the difference that the low molecular weight polybutadiene Poly vest EP-ST-E 100 used as the modifying agent having a molecular weight of 3250 g/mol was administered in a molar ratio to the neodymium of 1.0. Properties of the obtained polymer are presented in Table 2. The sample was also tested according to the formulation of rubber compositions ASTM 3189 (Table 3), the test results are shown in Table 4.

Example 6

It is analogous to example 5, with the difference that gadolinium versatate was used as a lanthanide salt, 2-methylbuta-l,3-diene-isoprene was used as a modifier, the molar ratio of polyisoprene to gadolinium was 5.0. The low molecular weight polybutadiene Polyvest EP-ST-E 80 used as a modifying agent has a molecular weight of 3250 g/mol.

Properties of the obtained polymer are presented in Table 2. The sample was also tested according to the formulation of rubber compositions ASTM 3189 (Table 3), the test results are shown in Table 4. Example 7

It is analogous to example 6, with the difference that neodymium tris-[bis-(2- ethylhexyl)phosphate] was used as a lanthanide salt, the mole ratio of Cl/Nd was 2.5. The low molecular weight polybutadiene Polyvest EP-ST-E 80 was used in a molar ratio to neodymium that is equal to 5.0.

Properties of the obtained polymer are presented in Table 2. The sample was also tested according to the formulation of rubber compositions ASTM 3189 (Table 3), the test results are shown in Table 4. Example 8

It is analogous to example 7, with the difference that neodymium tris-[(2- ethyl)hexanoate] was used as a lanthanide salt, and diethylaluminum chloride (DEAC) - as a chlorinating agent; the molar ratio of Cl/Nd was 2.3. The low molecular weight polybutadiene Polyvest EP-ST-E 80 was used in a molar ratio of 0.01 to neodymium.

Example 9 (comparative) It is analogous to example 5 but with the difference that isoprene was selected as the conjugated diene, diethylaluminium chloride was selected as the halogen- containing component , the molar ratio of Cl/Nd was 2.2. The low molecular weight polybutadiene Polyvest EP-ST-E 60 was used in a molar ratio of 8.0 to neodymium.

Example 10

It is analogous to example 9, but with the difference that 1,3-butadiene was selected as the conjugated diene, EASC was selected as the halogen-containing component , the molar ratio of Cl/Nd was 2.5. The molar ratio of the low molecular weight polybutadiene Polyvest EP-ST-E 60 to neodymium is 5.0.

Table 1

The characterization of liquid rubbers used according to the invention

* - silane-functionalized, low molecular weight (liquid) polybutadiene rubbers with different degrees of functionalization

(silanization).

Poly vest EP-ST-E 60 - 60% - silanization Polyvest EP-ST-E 80 - 80% - silanization Polyvest EP - ST-E 100 - 100% - silanization

Table 2

Polymer properties

Table 2. Continuation

List of the abbreviations presented in Table 2:

NdP3 - neodymium tris-[bis-(2-ethylhexyl)phosphate] NdV3 - neodymium neodecanoate GdV3 - gadolinium versatate NdEh3 - neodymium tris-[(2-ethyl)hexanoate] DEAC - diethylaluminium chloride

EASC - athylaluminumsesquichloride

Table 3

Formulation of rubber compositions (ASTM 3189)

Table 4

Plasto-elastic properties of rubber compositions * RPA 2000 Viscoelastic properties of rubber compositions [100°C; Freq.: 0.1

Flz; Strain Sweep : 1-300%]

As can be seen from Table 2, the degree of branching the polymer in the example according to the prototype is lower than in accordance with the present invention. The degree of branching affects the processability of the polymer at the stage of rubber mixing and the use of rubbers comprising such a polymer. The processability is evaluated in terms of the Mooney viscosity of rubber compositions, according to the examples of the invention the Mooney viscosity (Table 4) is significantly lower than in the prototype and comparative examples, which indicates the good processability. The benefits in the use of the rubbers comprising the obtained polymer may be estimated by the Shopper- Schlobach abrasion index (Table 4) - in the examples according to the invention the abrasion is much lower.

At the same time, other parameters such as the Mooney viscosity ML(l+4), the content of 1 ,4-cis units and an amount of high molecular weight fraction are level with one another. It is also obvious that the increase in the molar content of the modifier results in high branching of the polymer (example 9): the branching index tgh (1200%) is significantly lower than 4.0, which resulted in the formation of an insoluble polymer, from which it is difficult to take molecular weight characteristics.

Claims

1. A method for the preparation of a modified polydiene, comprising the following steps of: i) preparing a catalyst complex including

(A) a lanthanide compound, (B) a conjugated diene,

(C) an organoaluminum compound, and

(D) a halogen-containing component; ii) polymerizing a conjugated diene in an organic solvent in the presence of the catalyst complex obtained in step i); iii) on reaching at least 96% conversion of the monomer, introducing a modifying agent into the polymer, wherein the modifying agent is a low molecular weight polybutadiene containing terminal alkoxysilane groups; iv) terminating the polymerizate obtained in step iii), introducing an antioxidant and recovering the polymer the polymer.

2. The method according to claim 1, characterized in that low molecular weight polybutadiene containing terminal alkoxysilane groups are represented by the general formula (1): wherein R is a hydrocarbon radical representing a linear or branched Ci-Cio alkyl, preferably C1-C4 alkyl, where n is an integer from 1 to 3.

3. A method according to claim 1 or claim 2, characterized in that the low molecular weight polybutadiene having a molecular weight of from 1500 to 50000 g/mol is used.

4. A method according to any one of claims 1 to 3, characterized in that a molar ratio of a modifying agent to lanthanide is (0.01 to 5): 1, preferably (0.2-5): 1, more preferably (0.4-1): 1, wherein an number of moles of the lanthanide compound (A) is taken based on moles of the lanthanide, and the number of moles of the halogen- containing component (D) is taken based on moles of halogen.

5. A method according to any one of claims 1 to 4, characterized in that the modification process is more preferably carried out for from 15 minutes to 5 hours.

6. A method according to any one of claims 1 to 5, characterized in that the modification process is most preferably carried out for from 20 minutes to 2 hours.

7. A method according to any one of claims 1 to 6, characterized in that a molar ratio of the components of the catalyst complex (A):(B):(C):(D) is l:(5-30):(8- 30): (1.5 -3.0) respectively, preferably the molar ratio of the components of the catalyst complex (A):(B):(C):(D)=l:(5-20):(8-20):(l,8-2.8), wherein the number of moles of the lanthanide compound (A) is taken based on the number of moles of lanthanide and the number of moles of the halogen-containing component (D) is taken based on the number of moles of halogen.

8. A method according to any one of claims 1 to 7, characterized in that the molar ratio of the components of the catalyst complex (A):(B):(C):(D) is equal to 1 :(10-

15):(10-15):(2.1-2.5), wherein the number of moles of the lanthanide compound (A) is taken based on the number of moles of lanthanide, and the number of moles of the halogen-containing component (D) is taken based on the number of moles of halogen.

9. The method according to any one of claims 1 to 8, characterized in that 1,3- butadiene, isoprene, 2, 3-dimethyl- 1, 3-butadiene, piperylene, 2-methyl-3-ethyl-l,3- butadiene, 3-methyl-l,3-pentadiene, 2-methyl-3-ethyl-l,3-pentadiene, 3 -methyl- 1,3- pentadiene, 1,3-hexadiene, 2-methyl- 1, 3 -hexadiene, 1,3-heptadiene, 3 -methyl- 1,3- heptadiene, 1,3-octadiene, 3-butyl-l,3-octadiene, 3,4-dimethyl-l,3-hexadiene, 4,5- diethyl- 1,3 -octadiene, phenyl- 1,3 -butadiene, 2, 3 -diethyl- 1,3 -butadiene, 2,3-di-n-propyl- 1,3 -butadiene, 2-methyl-3-isopropyl-l, 3-butadiene are used as a conjugated diene; it is the most preferable to use 1,3-butadiene and isoprene as the conjugated diene.

10. A modified polydiene characterized by a Mooney viscosity of from 40 to

50 Mooney units, an amount of high molecular weight fraction (HMF is over 1 million a.m.u.) of not more than 3.5 wt.% and a branching index expressed in a mechanical loss tangent value tgb (1200%) equal to 4.0 to 6.0.

11. The modified polydiene obtained by the method according to any one of claims 1 to 10.

12. A rubber compound comprising the polydiene according to claim 10 or claim 11.