EP4077410A1

EP4077410A1 - Branched polydienes, rubber compositions based on thereof

Info

Publication number: EP4077410A1
Application number: EP19956695.1A
Authority: EP
Inventors: Tatiana Aleksandrovna IARTSEVA; Svetlana Alekseevna LAGUNOVA; Liliia Andreevna BOIKO; Olga Ivanovna ARTEMEVA
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: WO2021126003A1; EP4077410A4; CN114846031A; KR20220119102A

Abstract

The invention relates to the production of synthetic polymers used in the manufacture of tires and rubber technical products, in electrical industry and other fields. In particular, the present invention relates to a method for producing a branched polydiene by polymerization of a conjugated diene, the method comprising the following steps: preparing a catalyst complex consisting of a lanthanide compound, an organoaluminum compound, a conjugated diene and a halogen-containing component; polymerizing the conjugated diene in the presence of said catalyst complex; performing post-polymerization modification with at least one branching agent selected from halogen-containing compounds, phosphorus-nitrogen compounds or mixtures thereof; termination, introducing a plasticizer into the polymer, wherein the plasticizer is a low-molecular weight polymer having a molecular weight between 1500 and 50,000 g/mol, degassing, and drying the polymer. In yet another aspect, the present invention relates to a method for producing rubber compositions based on the above branched polydiene. The technical result of the present invention is the preparation of a branched polydiene characterized by a Mooney viscosity from about 40 to about 49 Mooney Units (MU) and a branching index, as characterized by a mechanical loss angle tangent tgδ (1200%), from about 4.7 to about 5.3. The polydiene produced according to the invention has an improved processability, an improved distribution of the filler in the polymer matrix, and rubber compositions based on it are characterized by improved elastic-hysteresis properties (namely, Mooney viscosity ML(1+4), MU, a Payne effect Δ(G'1%-G'50%), kPa, Tanδ 60°C at 10% deformation.

Description

BRANCHED POLYDIENES, RUBBER COMPOSITIONS BASED ON THEREOF

Field of the invention

The invention relates to the production of synthetic polymers used in the 5 manufacture of tires and rubber technical products in electrical industry and other fields.

In particular, the present invention relates to a method for producing a branched polydiene by polymerization of a conjugated diene, the method comprising the following steps: preparing a catalyst complex comprising a lanthanide compound, an organoaluminum compound, a conjugated diene and a halogen-containing component; 10 polymerizing the conjugated diene in the presence of said catalyst complex; performing post-polymerization modification using at least one branching agent selected from halogen-containing compounds, phosphorus-nitrogen compounds or mixtures thereof; termination, introducing a plasticizer into the polymer, wherein the plasticizer is a low- molecular weight polymer having a molecular weight of from 1500 to 50,000 g/mol, 15 degassing, and drying the polymer. In yet another aspect, the present invention relates to a method for producing rubber compositions based on the above branched polydiene.

The branched polydiene prepared according to the invention has a Mooney viscosity index between 40 and 49 Mooney Units (MU), a polydispersity index in the range from 2.16 to 2.60, a branching index, as characterized by a mechanical loss angle 20 tangent tg5 (1200%), from about 4.7 to about 5.3, and the content of 1,4-cis units between 96,0 and 98.0%. Rubber compositions based on the prepared polydienes are characterized by a low Mooney viscosity of the rubber compositions and exhibit good elastic-hysteresis properties.

25 Background

Nowadays, in order to increase competitiveness, it is extremely important for rubber producers to have advantages in properties considered in the environmental labeling of tires. In the furtherance of this goal, the rolling resistance index, which is responsible for 20-30% of fuel consumption by motor transport, must be optimized. A 30 reduction in rolling resistance will not only reduce fuel consumption, but also lead to a reduction in carbon dioxide emissions. The appearance on the market of a wide range of low molecular weight polymers, the so-called liquid rubbers, made it possible to obtain a winter non-studded tire with improved grip in winter conditions. Some companies already use liquid rubbers as a reinforcing additive in the tread compound. In tests, the treads thus obtained demonstrate high plasticity and keep the flexibility even at low temperatures, and also exhibit improved ice grip.

Patent RU2394692 (SUMITOMO RABBER INDASTRIES, LTD (JP), 07.20.2010) describes the production of a rubber composition for side walls of a pneumatic tire, containing: 100 parts by mass of a first rubber component consisting of 30 to 70 mass % of natural rubber and 70 to 30 mass % of epoxidized natural rubber, 20 to 60 parts by mass of silica, and 3 to 60 parts by mass of a second rubber component consisting of liquid rubber, and a vulcanizer. This provides an "ecological" pneumatic tire having improved durability (improved heat resistance, anti-crack property, ozone resistance).

However, the introduction of liquid rubber at the step of mixing rubber does not ensure its uniform distribution in the polymer matrix and, in addition, requires additional energy consumption. Further, according to this patent, only liquid polyisoprene rubber (natural rubber) was used.

The use of liquid polydienes as part of rubber compositions is widely known. Patent EP2082899 (CONTINENTAL AG (DE), 18.05.2011) describes a method for producing a rubber composition, consisting of 5-50 parts by mass of a liquid low viscosity polymer. The obtained mixture demonstrates an improved elasticity at low temperatures and an improved tensile modulus at 300% elongation.

Liquid rubber is also introduced at the step of rubber mixing, and any improvements in the physical and mechanical properties and elastic hysteresis properties of the rubber mixtures were not mentioned in patent.

A method for improving abrasion resistance of rubber compositions for the manufacture of tire tread, using functionalized liquid polybutadiene is known from US8975324 (RANDALL AMY M (US), AGARWAL SHEEL P (US), HERGENROTHER WILLIAM L (US), BRIDGESTONE CORP (JP), 10.03.2015). The rubber composition according to the invention comprises a conjugated diene polymer or copolymer; at least one filler; liquid polybutadiene, which is functionalized with an unsaturated carboxylic acid anhydride, in an amount of 2 to 10 phr; from 0.2 to 5 phr of zinc oxide; and from 1 to 100 phr of process oil. In this patent, the liquid rubber is introduced at the step of mixing rubber, and the comparison of rubber compositions with liquid rubber and rubber compositions based on oil-filled polymers demonstrates that the Mooney viscosity of the former is higher than that of the latter by 10-28%, which indicates poor processability; in addition, the rate of vulcanization of rubber compositions with liquid rubber is 1.5-2 times lower.

A rubber composition prepared as disclosed US6472461 (BRIDGESTONE CORP (JP), 29.10.2002) consists of 1) a rubber component, including a) at least one natural or synthetic diene rubber, b) low molecular weight polybutadiene with an average molecular weight of 5,000 to 30,000, as measured by gel permeation chromatography based on polystyrene molecular weight, in an amount of 6% or more based on rubber component, with a content of 1,4-cis structure of 60 to 98%; 2) a polyethylene short fiber having an average length of 10 mm or shorter; and 3) a blowing agent. The invention relates to a method for producing a pneumatic tire exhibiting improved braking ability on ice.

The inventors do not provide data on indices which are very important for tire manufacturers - abrasion, elastic-hysteresis properties at 60°C and strength properties of rubbers.

RU2429252 (BRIDGESTONE CORP (JP), 20.09.2011) also describes a method for introducing low-molecular weight polymers at the step of mixing rubber. The rubber mixture is prepared by mixing 1-60 parts by weight of a low molecular weight conjugated diene-based polymer (B) having a weight average molecular weight, as measured by gel permeation chromatography and converted to polystyrene, of more than 30,000 to not more than 200,000 per 100 parts by weight of rubber component (A) that is mixed with (B). The rubber component (A) comprises natural rubber and/or polyisoprene rubber, and optionally at least one rubber selected from the group consisting of styrene-butadiene copolymer rubber, polybutadiene rubber and isobutylene isoprene rubber. The composition according to the invention has excellent workability during production and the heat resistance, high in the storage elastic modulus and small in the loss tangent (tg d). However, the introduction of liquid rubber at the step of mixing rubber does not ensure its uniform distribution in the polymer matrix.

It is known that during post-polymerization and polymerization modification with maleic fragments, the active center (growing macromolecule) interacts with carbonyl groups, followed by a change in the molecular parameters and plasto-elastic properties of polybutadienes. In addition, new phenomena have been discovered. In particular, when a modifier is introduced directly to the finished catalyst complex (polymerization modification), the modifier not only interrupts the polymerization process, but also provides results close to the post-polymerization modification (V.L. Zolotarev, On the mechanism of the process of post-polymerization modification of neodymium 1,4-cis-polybutadiene, J."Vysokomolekulyamye soedineniya" [High Molecular Compounds], No. 3, p.3-5, 2015).

However, the use of maleinized polybutadiene alone for modification, regardless of the time of its introduction, does not impart optimal performance properties to rubbers.

A promising direction is the post-polymerization modification of low molecular weight polymers, which have an effect on the properties of 1 ,4-cis polybutadienes and rubber compositions based oh them.

The method for preparing polybutadiens as disclosed in US7112632 (POLIMERI EUROPA SPA (IT), 26.09.2006) is closest to the essence of the present invention. According to this method, the process of the preparation of polybutadienes comprises: (a) polymerization of butadiene;

(b) treatment of the polymer solution obtained upon completion of step (a) with a coupling agent that is 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 step (b). According to the patent, the obtained polymers have a low branch content.

However, it is known that good processability of rubber compounds is ensured by using branched polymers. The patent does not contain any information on the uniformity of distribution of the filler in the polymer matrix, as well as on an improvement in abrasion and processability of the obtained polymer.

Disclosure of the invention

The objective of the present invention is an improvement in processability of polymers at the step of rubber mixing.

This objective is addressed by developing a method for preparing a branched poly diene by polymerization of a conjugated diene, the method comprising: preparing a catalyst complex comprising a lanthanide compound, an organoaluminum compound, a conjugated diene and a halogen-containing component; polymerizing the conjugated diene in the presence of said catalyst complex; performing post-polymerization modification with at least one branching agent selected from halogen-containing compounds, phosphorus-nitrogen compounds or mixtures thereof; termination, introducing a plasticizer into the polymer, wherein the plasticizer is a low-molecular weight polymer having a molecular weight between 1500 and 50,000 g/mol, degassing, isolating, and drying the polymer.

The technical result of the present invention is the preparation of a branched polydiene characterized by a Mooney viscosity from about 40 to about 49 Mooney Units (MU) and a branching index, as characterized by a mechanical loss angle tangent tg5 (1200%), from about 4.7 to about 5.3. The polydiene prepared according to the invention has an improved processability, an improved distribution of the filler in the polymer matrix, and rubber compositions based on it are characterized by improved elastic-hysteresis properties (namely, Mooney viscosity ML(l+4), MU, a Payne effect A(G'1%-G’50%), kPa, tg560°C at 10% deformation).

According to the invention, the modification is performed by means of using at least one branching agent selected from halogen-containing compounds, phosphorus- nitrogen compounds or mixtures thereof.

Compounds used as a branching halogen-containing compound include thionyl chloride, diphenyltin dichloride, phenyltin trichloride, triphenyltin chloride, dibutyltin dichloride, butyltin trichloride, tin tetrachloride, and silicon tetrachloride.

The phosphorus-nitrogen compound is a compound with a chemical structure based on repeating units of (-P=N-)_n, where n is an integer from 3 to 24. The branching agent interacts with a polymer at the active ends of its polymer chain. The branching agent influences the Mooney viscosity and branching index of the polymer, a change in the molecular weight characteristics of the polymer, such as number-average molecular weight Mn, weight-average molecular weight Mw, polydispersity Mw/Mn and others.

Plasticizers (emollients) are substances that, when introduced into the polymer, facilitate its processing. In this case, the plasticizer does not chemically interact with the polymer; only physical mixing takes place. Plasticizers are added, as a rule, at the step of mixing rubber. The presence of classic liquid plasticizers in the formulation of rubber mixtures at the step of mixing rubber allows, to some extent, homogenization of the rubber mixture; however, in most cases, significant dosages (on average 15 parts by weight) negatively affect the complex of physicochemical properties of the resulting vulcanizates.

A distinguishing feature of the present invention is the introduction of a plasticizer in the form of a solution in an inert organic solvent at the step of preparing polymer. This technique allows the use of low dosages of a plasticizer (in an amount of 6 or more times lower compared with the amount introduced at the step of mixing rubber) and an increase in the processability by at least 6-10% in comparison with a polymer that has undergone only post-polymerization modification without the addition of a plasticizer.

In accordance with the present invention, a plasticizer is used in the step of preparing polymer, wherein the plasticizer is a low molecular weight polymer with a molecular weight between 1,500 and 50,000 g/mol. Non-functionalized low molecular weight polybutadienes, polybutadienes functionalized with maleic anhydride or triethoxysilane, as well as non-functionalized low molecular weight polyisoprenes and polyisoprenes functionalized with maleic anhydride are preferably used as such a plasticizer.

Non-functionalized low molecular weight polybutadienes and polybutadienes functionalized with maleic anhydride or triethoxysilane are most preferable as a plasticizer since they have the same microstructure as neodymium polybutadiene.

Exemplary commercially available plasticizers are: isoprene homopolymer (e.g., LIR-30, LIR-50 produced by Kuraray Co., Ltd.), polyisoprene modified with maleic anhydride (e.g. MIP-004 Kuraray Co., Ltd.), non-functionalized low molecular weight (“liquid”) polybutadiene (for example, Polyvest 130 from Evonik), polybutadienes functionalized with maleic anhydride (for example, Polyvest 75MA from Evonik or Ricon 130 MA 8, Ricon 130 MA 10, Ricon 130 MA 13, Ricobond 1031, Ricobond 1731, Ricobond 2031, Ricobond 1756 from Cray Valley) or triethoxysilane (e.g. Polyvest EP ST-E 60, Polyves t EP ST-E 80, Polyvest EP ST-E 100 from Evonik). Characteristics of plasticizers (liquid rubbers) used according to the invention are shown in Table 2.

The dosage of a plasticizer according to the invention is 0.5-5.0 mass.% based on polymer, the preferred dosage is 0.7-2.0 mass.%, the most preferred dosage of the plasticizer according to the invention is 0.8-1.5 mass.%. Dosages of the plasticizer above the defined range result in significant decrease in the Mooney viscosity of the polymer, and in a decrease in the conditional tensile strength in rubber compositions. A dosage less than 0.5 mass.% does not lead to improvements in the properties of polymer and rubber compositions based on it.

A catalyst complex used according to the invention comprises a lanthanide compound, an organoaluminum compound and a halogen-containing component. Compounds used as a lanthanide compound include compounds comprising at least one lanthanide atom: neodymium, lanthanum, cerium, praseodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium. Neodymium is preferred.

Compounds containing lanthanides include, but are not limited to them, such as carboxylates, organophosphates (in particular alkyl phosphates and aryl phosphates), organophosphonates (in particular alkyl phosphonates and aryl phosphonates), organophosphinates (in particular alkyl phosphinates and aryl phosphinates), carbamates, lanthanide xanthates, b-diketonates, halides, oxyhalides, alcoholates.

Neodymium carboxylates include neodymium formate, neodymium acetate, neodymium acrylate, neodymium methacrylate, neodymium valerate, neodymium gluconate, neodymium citrate, neodymium fumarate, neodymium lactate, neodymium maleate, neodymium oxalate, neodymium 2-ethylhexanoate, neodymium neodecanoate, neodymium naphthenate, neodymium stearate, neodymium oleate, neodymium benzoate, and neodymium picolinate. Neodymium organophosphates include neodymium dibutyl phosphate, neodymium diphenyl phosphate, neodymium dihexyl phosphate, neodymium diheptyl phosphate, neodymium dioctyl phosphate, neodymium bis(l-methylheptyl)phosphate, neodymium bis(2-ethylhexyl)phosphate, neodymium didecyl phosphate, neodymium didodecyl phosphate, neodymium dioctadecyl phosphate, neodymium bis(n- nonylphenyl)phosphate, neodymium butyl(2-ethylhexyl)phosphate, neodymium (1- methylphenyl)(2-ethylhexyl)phosphate, and neodymium (2-ethylhexyl)(n- nonylphenyl)phosphate.

Neodymium organophosphonates include neodymium butylphosphonate, neodymium pentylphosphonate, neodymium hexylphosphonate, heptylphosphonate neodymium, neodymium octylphosphonate, neodymium (l-methylheptyl)phosphonate, neodymium (2-ethylhexyl)phosphonate, neodymium decylphosphonate, neodymium dodecylphosphonate, neodymium octadecylphosphonate, neodymium oleylphosphonate, neodymium phenylphosphonate, neodymium (n- nonylphenyl)phosphonate, neodymium butyl(butylphosphonate), neodymium pentyl(pentylphosphate), neodymium hexyl(hexylphosphonate), neodymium heptyl(heptylphosphonate), neodymium octyl(octylphosphonate), neodymium (1- methylheptyl)((l-methylheptyl)phosphonate), neodymium (2-ethylhexyl)((2- ethylhexyl)phosphonate), neodymium decyl(decylphosphonate), neodymium dodecyl(dodecylphosphonate), neodymium octadecyl(octadecylphosphonate), neodymium oleyl(oleylphosphonate), neodymium phenyl(phenylphosphonate), neodymium (n-nonylphenyl)((n-nonylphenyl)phosphonate), neodymium butyl((2- ethylhexyl)phosphonate), neodymium (2-ethylhexyl)(butylphosphonate), neodymium ( 1 -methylheptyl)((2-ethylhexyl)phosphonate), neodymium (2-ethylhexyl)(( 1 - methylheptyl)phosphonate), neodymium (2-ethylhexyl)((n-nonylphenyl)phosphonate), and neodymium (p-nonylphenyl)((2-ethylhexyl)phosphonate).

Neodymium organophosphinates include neodymium butylphosphinate, neodymium pentylphosphinate, neodymium hexylphosphinate, neodymium heptylphosphinate, neodymium octylphosphinate, neodymium (1- methylheptyl)phosphinate, (2-ethylhexyl)phosphinate, neodymium decylphosphinate, neodymium dodecylphosphinate, neodymium octadecylphosphinate, neodymium oleylphosphinate, neodymium phenylphosphinate, neodymium (n- nonylphenyl)phosphinate, neodymium dibutylphosphinate, neodymium dipentylphosphinate, neodymium dihexylphosphinate, neodymium diheptylphosphinate, neodymium dioctylphosphinate, neodymium bis(l-methylheptyl)phosphinate, neodymium bis(2-ethylhexyl)phosphinate, tris-[bis(2- ethylhexyl)phosphinate]neodymium, neodymium didecylphosphinate, neodymium didodecylphosphinate, neodymium dioctadecylphosphinate, neodymium dioleylphosphinate, neodymium diphenylphosphinate, neodymium bis(n- nonylphenyl)phosphinate, neodymium butyl(2-ethylhexyl)phosphinate, neodymium (1- methylheptyl)(2-ethylhexyl)phosphinate, and neodymium (2-ethylhexyl)(n- nonylphenyl)phosphinate.

Carboxylates of neo acids are most preferred due to their faster and more complete alkylation, which results in more active catalyst compounds.

It is preferred to use noeodymium carboxylates and organophosphinates, among which neodymium neodecanoate and tris-[bis(2-ethyhexyl)phosphate]neodymium or mixtures thereof are most preferred.

Compounds suitably used as an ofganoaluminum compound according to the invention include trialkyl aluminum compound, triphenyl aluminum or dialkyl aluminum hydrides, alkyl aluminum dihydrides, in particular, trimethyl aluminum, triethyl aluminum, tri-n-propyl aluminum, triisopropyl aluminum, tri-n-butyl aluminum, triisobutyl aluminum, tri-tert-butyl aluminum, triphenyl aluminum, trihexyl aluminum, tricyclohexyl aluminum, trioctyl aluminum, diethyl aluminum hydride, di-n-propyl aluminum hydride, di-n-butyl aluminum hydride, diisobutyl aluminum hydride, dihexyl aluminum hydride, di-isohexyl aluminum hydride, dioctyl aluminum hydride, diisooctyl aluminum hydride, phenyl ethyl aluminum hydride, phenyl-n-propyl aluminum hydride, phenyl isopropyl aluminum hydride, phenyl-n-butyl aluminum hydride, phenyl isobutyl aluminum hydride, benzyl ethyl aluminum hydride, benzyl-n-butyl aluminum hydride, benzyl isobutyl aluminum hydride, benzyl isopropyl aluminum hydride and the like.

The use of alkyl aluminum or alkyl aluminum hydrides, or mixtures thereof is preferred. The most preferred is triethyl aluminum, triisobutyl aluminum, diisobutyl aluminum hydride or a mixture thereof. Compounds used as conjugated dienes according to the invention include 1,3- butadiene, isoprene, 2,3-dimethyl-l,3-butadiene, piperylene, 2-methyl-3-ethyl-l,3- butadiene, 3-methyl- 1,3-pentadiene, 2-methyl-3-ethyl-l,3-pentadiene, 3-methyl-l,3- pentadiene, 1,3-hexadiene, 2-methyl- 1, 3 -hexadiene, 1,3-heptadiene, 3-methyl-l,3- heptadiene, 1,3-octadiene, 3-butyl-l,3-octadiene, 3, 4-dimethyl- 1,3 -hexadiene, 4,5- diethyl-l,3-octadiene, phenyl- 1,3 -butadiene, 2, 3-diethyl-l, 3-butadiene, 2,3-di-n-propyl- 1,3 -butadiene, and 2-methyl-3 -isopropyl- 1,3 -butadiene.

The most preferred conjugated dienes are 1,3-bytadiene and isoprene.

Compounds used as a halogen-containing component in the catalyst complex may include halo-organic compounds of aluminum and tin, in particular, such as dimethyl aluminum chloride, diethyl aluminum chloride, diisobutyl aluminum chloride, dimethyl aluminum bromide, diethyl aluminum bromide, diisobutyl aluminum bromide, dimethyl aluminum fluoride, diethyl aluminum fluoride, diisobutyl aluminum fluoride, dimethyl aluminum iodide, diethyl aluminum iodide, diisobutyl aluminum iodide, methyl aluminum dichloride, ethyl aluminum dichloride, methyl aluminum dibromide, ethyl aluminum dibromide, methyl aluminum difluoride, ethyl aluminum difluoride, methyl aluminum sesquichloride, ethyl aluminum sesquichloride, isobutyl aluminum sesquichloride or mixtures thereof, as well as trimethyltin chloride, trimethyltin bromide, triethyltin chloride, triethyltin bromide, di-tert-butyltin dichloride, di-tert- butyltin dibromide, dibutyltin dichloride, dibutyltin dibromide, tributyltin chloride and tributyl bromide and the like, or mixtures thereof.

Preferred halogen-containing components are ethyl aluminum sesquichloride, ethyl aluminum dichloride, diethyl aluminum chloride or mixtures thereof.

The polymerization solvent is an inert organic solvent, such as aliphatic hydrocarbon, in particular, such as butane, pentane, hexane, heptane; alicyclic hydrocarbon, in particular, cyclopentane, cyclohexane; mono-olefin, such as 1 -butene, 2-butene, or mixtures thereof; aromatic hydrocarbon, in particular, such as benzene, toluene, xylene, which can be used individually or in a mixture with each other.

According to the proposed method, the most preferred hydrocarbon solvent is a solvent, which is a mixture of cyclohexane with hexane or cyclohexane with neffas (commercial-grade hexane-heptane fraction of paraffinic hydrocarbons of dearomatized gasolines obtained by catalytic reforming process, having a boiling point of 65-75 °C) in a ratio of (30-55)÷(70-45).

A catalyst complex used in the polymerization process according to the invention comprises a lanthanide compound (A), a conjugated diene (B), an organoaluminum compound (C), and a halogen-containing component (D) in a molar ratio of (A):(B):(C):(D) of l:(5-30):(8-30):(l.5-3.0).

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

The most preferred molar ratio of (A):(B):(C):(D) components of the catalyst complex is l:(10-15):(10-15):(2.1-2.5).

The process of preparing a diene polymer is a batch or continuous process performed in a hydrocarbon solvent by feeding a hydrocarbon mixture to a polymerization vessel (reactor/autoclave), wherein the hydrocarbon mixture consists of a monomer and a solvent and a catalyst complex premixed with the solvent, wherein the catalyst complex comprises a lanthanide compound, a conjugated diene, an organoaluminum compound, and a halogen-containing component. The concentration of the monomer in the solvent is, as a rule, between 7 and 12 mass.%, preferably between 9 and 10%. A concentration below 7% leads to a decrease in the energy efficiency of the process, and a concentration above 12% leads to an increase in polymerizate viscosity, and, consequentially, to an increase in the energy consumption during isolation and drying of the rubber.

The catalyst complex (CC) is prepared by introducing an organoaluminum compound (most preferably, triisobutyl aluminum, triethyl aluminum, diisobutyl aluminum hydride or mixtures thereof), a lanthanide compound (most preferably, carboxylate, in particular neodecane or tris-[bis(2-ethylhexyl)neodymium phosphate) in a solution of a conjugated diene (most preferably, 1,3 -butadiene) in an aliphatic solvent; aging the resulting mixture for 2 to 20 hours at a temperature of 23±2°C followed by the addition of a halogen-containing component (most preferably, ethyl aluminum sesquichloride, ethyl aluminum dichloride, diethyl aluminum chloride or mixtures thereof), at a molar ratio of (A):(B):(C):(D) components of the catalyst complex of 1 :(5- 30):(8-30):(l, 5-3,0), wherein (A) is the lanthanide compound, (B) is the conjugated diene, (C) is the organoaluminum compound and (D) is the halogen-containing component. The dosage of the catalyst complex is calculated based on the monomer (hydrocarbon mixture), and for component (A) the calculation is carried out based on lanthanide (metal), namely, 1.0-3.0 mol of lanthanide per 1 ton of monomer.

The time of polymerization is from 1.5 to 3 hours. The monomer conversion rate reaches 95 to 99%.

Upon reaching at least 95% monomer conversion, 2 kg of polymerizate are discharged, an antioxidant solution in an amount of 0.2 to 0.4 mass.% based on polymer is added to stabilize the polymer, degassed and dried on rollers at a temperature of 75- 85°C. The resulting product is used as a non-modified reference sample. The reference polymer has a Mooney viscosity of 30-39 MU and is characterized by a linear structure: its branching index as characterized by a mechanical loss angle tangent tg6 (1200%) is 9-7 units.

Then, a branching agent selected from phosphorus-nitrogen and/or halogen- containing compounds is fed into the remaining polymerizate. The process of branching is conducted for from 5 minutes to 3 hours, preferably from 20 minutes to 1 hour, with constant stirring at a temperature of 60-90°C. At the end of the branching process, 2 kg of polymerizate are discharged, an antioxidant solution is added to the polymer in an amount of 0.2 to 0.4 mass.% based on polymer, degassed and dried on rollers at a temperature of 75-85°C.

A modification temperature below 60°C leads to an increase in the polymer viscosity, which is undesirable because it rises inevitable difficulties in isolation and processing of the polymer. At the same time, the end groups of the polymer chain tend to lose their activity at temperatures above 90°C, and, as a consequence, a high degree of branching of polymer is impossible.

Compounds useful as a branching agent (BA) according to the present invention are phosphorus-nitrogen and/or halogen-containing compounds.

Suitable halogen-containing compounds may include tin compounds, namely tin tetrachloride, methyltin trichloride, dimethyltin dichloride, ethyltin trichloride, diethyltin dichloride, n-butyltin trichloride, di-n-butyltin dichloride, phenyltin trichloride, diphenyltin dichloride, as well as silicon compounds, such as silicon tetrafluoride, silicon tetrachloride, silicon tetrabromide, and silicon tetraiodide. Tin tetrachloride, methyltin trichloride, ethyltin trichloride, butyltin trichloride, and silicon tetrachloride are preferred. In the most preferred embodiment, tin tetrachloride and silicon tetrachloride are used,

The dosage of the introduced branching agent depends on desired properties of the final product, such as the Mooney viscosity of the polymer, while an increase in the Mooney viscosity of the polymer (D ML,%) after its branching in comparison with non- branched polymer is 30-40%, and the branching index characterized by a mechanical loss angle tangent tg5 (1200%), as measured on an RPA (rubber processing analyzer) device at a frequency of 0.1 Hz and a temperature of 100°C, characterizing the degree of branching of the polymer, changes by 35-50 mass.%.

According to the present invention, the molar ratio of the halogen-containing compound selected as a branching agent BA to lanthanide is from 1.0 to 20, preferably from 2 to 15, most preferably from 5.0 to 10.0. An increase in the dosage more than 20.0 moles gives no improvement in the properties of the polymer, but results in excessive consumption of BA. A decrease in the molar dosage less than 1.0 per lanthanide does not change the properties of the polymer and rubber, respectively.

According to the invention, the phosphorus-nitrogen compound is a compound with a chemical structure based on repeating Units of (-P=N-)_n, where n is an integer from 3 to 24. Exemplary compounds used as the phosphorus-nitrogen compound are, but are not limited to them:

2.2.4.4.6.6-hexachloro-l,3,5-triaza-2,4,6-triphosphorine;

2.4.6-trichloro-2,4,6-triphenoxycyclotriphosphazene;

1 , 1 -diphenyl-3 ,3, 5, 5-tetramethylaminotriphosphoronitrile;

2,2,4,4-tetrachloro-6,6-dimethylmercaptocyclotriphosphazatrien; ethyloxypentafluorocyclotriphosphazene;

(trifluoroethoxy)pentachlorocyclotriphosphazene; hexafluorocyclotriphosphazene;

4.4.6.6-tetrachloro-l,3,5-triaza-2,4,6-triphosphocyclohexa-l,3,5-triene-2,2- diamine;

2.4.6-trichloro-2,4,6-trifluoro-l,3,5-triaza-2 5,4 5,6 5-triphosphacyclohexa- 1,3,5-triene;

2.4.6-trichloro-2,4,6-tri(phenoxy)- 1 ,3 ,5-triphosphorine; trichloride trinitride diamide tetrachloride; octachlorocyclotetraphosphazene;

1 , 1 -dimethyl-3 ,3 ,5 ,5-tetrachlorocyclotriphosphazene;

2,2,4,4-tetrachloro-6-isopropyl^5^5^5-[l,3,5,2,4,6]triaza triphosphinine;

1 -methyl- 1 ,3 ,3 , 5 , 5 -pentachlorocyclotriphosphazene;

1.3.5.2.4.6-triazatriphosphorine, 2,4,6-tribromo-2,4,6-trifluoro polymer dialdehyde;

4.6-difhioro-2-N,N-2,2-N'2-N',4-N,4-N,N-6,6-N-octemethyl-l,3,5-triaza- 2 5,4 5,6>.5-triphospha-cyclohexa-l,3,5-triene-2,2,4,6-tetramine;

2.2.4.4.6.6-hexahydro-2,2,4,4,6.6-hexapropoxy-propoxy-l,2,3,4,5,6- triazatriphosphorine;

1,1 -diphenyl-3, 3, 5, 5-tetramethylamino-triphosphoronitrile and other.

In a preferred embodiment, chlorine-containing phosphorus-nitrogen compounds comprising from 2 to 6 chlorine atoms are used.

In the most preferred embodiment the used compounds are: 2, 2, 4, 4, 6, 6- hexachloro-l,3,5-triaza-2,4,6-triphosphorine; 2,4,6-trichloro-2,4,6- triphenoxycyclotriphosphazene; 2,2,4,4-tetrachloro-6,6- dimethylmercaptocyclotriphosphazatrien, 4,4,6,6-tetrachloro-l,3,5-triaza-2,4,6- triphosphocyclohexa-1, 3, 5-triene-2, 2-diamine or mixtures thereof.

In accordance with the present invention, the dosage of the phosphorus-nitrogen compound selected as BA is from 0.5 to 15.0 mol per mol of lanthanide. An increase in the molar dosage of more than 15.0 based on lanthanide does not lead to an improvement in the properties of the polymer and rubber, but results in excessive consumption of the modifier. A decrease in the molar dosage of less than 0.5 based on lanthanide does not improve the properties of the polymer and rubber, respectively.

The most preferred dosage of the chlorine-containing phosphorus-nitrogen compound is 1.0-5.0 mol per 1 mol of lanthanide since this amount of the modifier allows the achievement of optimal properties of the polymer and rubber based on it with a relatively small consumption of the modifier.

The resulting branched polymer is characterized by a Mooney viscosity between 44 and 53 MU and a branching index, as characterized by a mechanical loss angle tangent tg6 (1200%), between 4.0 and 5.0. In addition, an increase in Mooney viscosity of the branched polymer relative to the non-modifled reference sample is in the range of 30-50%.

An increase in viscosity (%) is calculated by the formula:

AML₂/I=(ML₂-MLI)/MLI * 100, wherein AML₂/I is an increase in Mooney viscosity of branched polymer relative to linear polymer;

ML₂ is Mooney viscosity of branched polymer;

MLi is Mooney viscosity of linear polymer;

A change in the branching of polymer (%) is calculated by the formula:

Atg5 1200%_2/I = (tg6 1200%₂ - tg5 1200%i)/tg5 1200%i*100, where Atg6 1200%_2/I is a change in the branching of polymer relative to linear polymer; tg6 1200%₂ is the branching index of branched polymer, expressed in a mechanical loss angle tangent determined in a variable amplitude from 0 to 1200%, a frequency of 0.1 Hz, and a temperature of 100°C; tg6 1200%i is the branching index of linear polymer, expressed in a mechanical loss angle tangent determined in a variable amplitude from 0 to 1200%, a frequency of 0.1 Hz, and a temperature of 100°C.

Further, a solution of an antioxidant in an amount of from 0.2 to 0.4 mass.% based on polymer and a plasticizer, which is a low molecular weight polymer with a molecular weight between 1500 to 5000 g/mol, in a dosage of 0.5-5.0 mass.% based on polymer are introduced into the remaining polymerizate, stirred for 5-10 min, degassed and dried on rollers at a temperature of 75-85°C.

The dosage of the plasticizer is calculated so that a drop of the polymer viscosity after introducing the plasticizer does not exceed 10% and a change in the branching index is not more than 10%. Otherwise, the conditional tensile strength deteriorates.

The drop of viscosity ML3/₂ is calculated by the formula:

AML_3/2 = (ML₂ - ML₃)/ML₂* 100, wherein AML_3/2 is a drop of Mooney viscosity of polymer;

ML₂ is Mooney viscosity of branched polymer;

ML₃ is Mooney viscosity of polymer branched and modified with a plasticizer.

A change in the branching of polymer (%) is calculated by the formula: Atg5 1200%3/2 = (tg6 1200%3 - tg6 1200%₂)/ tg5 1200%₂ *100, wherein Atg8 1200%_3/2 is a change in the branching of polymer; tg6 1200%₂ is the branching index of branched polymer, expressed in a mechanical loss angle tangent determined in a variable amplitude from 0 to 1200%, a frequency of 0.1 Hz, and a temperature of 100°C; tg6 1200%₃ is the branching index of branched and modified polymer, expressed in a mechanical loss angle tangent determined in a variable amplitude from 0 to 1200%, a frequency of 0.1 Hz, and a temperature of 100°C.

Rubber compositions are processed on the rollers after mixing, wherein the preparation of rubber compositions for vulcanization, vulcanization and preparation of test samples are performed according to ASTM D 3182 and ASTM D 3189. The ASTM D 3189 formulation is presented in Table 1.

The branched polydiene prepared according to the invention has a Mooney viscosity index between 40 and 49 MU, a polydispersity index in the range from 2.16 to 2.60, a branching index, as characterized by a mechanical loss angle tangent tg6 (1200%), between 4.7 and 5.3, wherein the content of 1,4-cis units is from 96,0 to 98.0%. The rubber mixtures obtained based on the prepared polydienes are characterized by a low Mooney viscosity, good distribution of a filler in the polymer matrix, and good elastic-hysteresis properties (namely, ML(l+4), MU, Payne effect A(G'1%-G'50%), kPa, tg560°C at 10% deformation).

The use of BA and a plasticizer in accordance with the present invention provides a branched polydiene, which in tests of rubber compositions shows better results in processability and better elastic-hysteresis properties in comparison with non- modified polymers, polymers modified with only one BA or their mixtures, but without a plasticizer, as well as in comparison with polymers prepared using a plasticizer only.

Table 1. Formulation of rubber mixtures (ASTM 3189)

Embodiments of the invention

Embodiments of the present invention are disclosed below. A person skilled in the art would understand that the invention is not limited to the presented examples only, and the same effect can be achieved in other embodiments without exceeding the object of the claimed invention.

Test methods used to evaluate the properties of the polymers prepared by the claimed method are disclosed below.

1. Conversion percentage is determined gravimetrically by precipitation of polymer with ethyl alcohol from polymerizate, drying the isolated polymer and calculating the weight fraction of the polymer in the polymerizate.

2. Molecular weight characteristics of rubbers were measured using gel permeation chromatography according to the method provided by the inventors of the present invention using a gel chromatograph (Waters Breeze System) with a refractometric detector. Samples of rubbers were dissolved in freshly distilled tetrahydrofuran, the weight concentration of polymer in the solution was 2 mg/ml; universal calibration was carried out with polystyrene standards. The calculation was made using the Kuhn-Mark-Houwink constants for polydiene (K = 0.00041, a = 0.693). Test conditions:

- a bank of 4 high-resolution columns (300 mm in length, 7.8 mm in diameter) filled with Styragel (HR3, HR4, HRS, HR6), which allows analysis of polymers with a molecular weight of 500 to 1 * 10⁷ amu;

- tetrahydrofuran solvent at a flow rate of 1 cmVmin;

- a temperature of thermostat columns and reffactometer of 3000°C.

3. The Mooney viscosity was determined according to ASTM D 1646. 4. The elastic component of the complex dynamic shear modulus G' (kPa) for evaluation of the distribution of a filler in rubber compositions and silanization of the filler was determined on an RPA-2000 rubber processing analyzer (Alpha Technologies) at 0.1 Hz and 100°C in the deformation range from 1 to 450%. A difference between storage moduli measured at strain amplitudes of 1% and 50% was CG’ = (G’ 1 % - G’43%), the Payne effect. 5. The branching index characterized by a mechanical loss angle tangent tg5 (1200%) was determined on an RPA-2000 rubber processability analyzer (Alpha Technologies) using the following test mode: a change in tg6 was evaluated in variable shear amplitude in the amplitude range from 10 to 1200% at a frequency of 0.1 Hz and a temperature of 100°C.

Example 1 (according to the prototype)

Butadiene (BD) was polymerized in a hydrocarbon solvent in the presence of a catalyst complex prepared based on neodymium versatate (Nd), followed by the addition of diisobutyl aluminum hydride (DIBAG) as an alkylating agent, diethyl aluminum chloride (DEAC) as a halogen donor, neodymium versatate (NdV3), diisobutyl aluminum hydride (DIBAH). DIBAH was taken in 8-fold molar excess relative to the dosage of neodymium, and DEAC was taken in a 3-fold molar excess. The dosage of the catalyst complex was 2.8 mol of neodymium per 1 ton of butadiene (BD). The polymerization was carried out in a 20-liter reactor equipped with a mixing device and a jacket for heat removal. The polymerization process lasted 90 minutes. At the end of the polymerization, 2 liters of polymerizate were discharged from the reactor; the monomer conversion was 98%. A phenolic antioxidant was added to the selected aliquot in an amount of 0.06 mass.% (Irganox 1520). The solvent was removed, the rolling was carried out at a temperature of 80°C. The molecular weight characteristics (MMC) measured by GPC and the branching index of the polymer were determined in the selected aliquot; the prepared linear polymer had a Mooney viscosity of 35 MU. A solution of maleinized polybutadiene Ricon 130 MA 8 in a mixture of hexanes (concentration of the solution 0.15 mol/L) at a dosage of 1.2 mol per Nd was fed into the polymerizate remaining 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 discharged. The modified polymer had a Mooney viscosity of 43 MU and tg6 1200% = 5.567, i.e. the obtained polymer was branched.

Example 2 (comparative)

Butadiene (BD) was polymerized in a hydrocarbon solvent in the presence of a preformed catalyst complex: neodymium neodecanoate - butadiene (BD) - diisobutyl aluminum hydride (DIBAH) - ethyl aluminum sesquichloride (EASC) at a component molar ratio of 1:10:12:2.5. The time of aging the complex was 22 hours at a temperature of 23 °C. The polymerization was carried out in a 20-liter reactor. The dry residue was equal 11%. The dosage of the catalyst complex was 1.8 mol of neodymium per 1 ton of butadiene (BD). After achieving a conversion rate of more than 95% based on monomer, 2 kg of polymerizate were discharged, a solution of a phenolic antioxidant was introduced in an amount of 0.3 mass.% based on the polymer to stabilize the polymer, degassed and dried on rollers at a temperature of 75-85°C. After that, physical and mechanical properties and molecular weight characteristics were determined (Table 3). An antioxidant solution in an amount of 0.3 mass.% based on polymer and low- molecular weight polybutadiene Polyvest 130 at a dosage of 0.8% mass. (8 g per kg of polybutadiene) were added to the remaining polymer, stirred for 10 min, degassed and dried on rollers at a temperature of 80°C. Physical and mechanical properties, molecular weight characteristics, an increase in polymer viscosity, and a change in the branching index (mechanical loss angle tangent tg6 (1200%)) are shown in Table 3.

Example 3 (comparative)

Butadiene (BD) was polymerized in a hydrocarbon solvent in the presence of a catalyst complex: neodymium neodecanoate - butadiene (BD) - diisobutyl aluminum hydride (DIB AH) - ethyl aluminum sesquichloride (EASC) at a component molar ratio of 1:10:11:2.5. The time of aging the complex was 20 hours at a temperature of 24°C. The dosage of the catalyst complex was 1.7 mol of neodymium per 1 ton of butadiene (BD).

After achieving a conversion rate of more than 95% based on monomer, a branching agent, 2,2,4,4,6,6-hexachloro-l,3,5-triaza-2,4,6-triphosphorine (HCF), was fed in a dosage of 1.0 mol based on neodymium. The modification process was continued for 60 minutes with constant stirring at a temperature of 80°C, then 2 kg of polymerizate were discharged, an antioxidant solution was introduced in an amount of 0.4 mass.% based on polymer, degassed and dried on rollers at a temperature of 80°C. The properties of the obtained polymers are shown in Table 3.

Example 4 (according to the invention)

Butadiene (BD) was polymerized in a hydrocarbon solvent in the presence of a catalyst complex: neodymium neodecanoate - butadiene (BD) - diisobutyl aluminum hydride (DIBAH) - ethyl aluminum sesquichloride (EASC) at a component molar ratio of 1:10:13:2.5, wherein the amount of neodymium neodecanoate is given based on the amount of neodymium. The dosage of the catalyst complex was 1.7 mol of neodymium per 1 ton of butadiene (BD). After achieving a conversion rate of more than 95% based on monomer, 2 kg of polymerizate were discharged, a phenolic antioxidant solution was introduced in an amount of 0.3 mass.% based on polymer to stabilize the polymer, degassed and dried on rollers at a temperature of 75 °C (step 1), a branching agent,

2.2.4.4.6.6-hexachloro-l,3,5-triaza-2,4,6-triphosphorine (HCF), was fed into the remaining polymer at a dosage of 1.3 mol per 1 mol of neodymium, 2 kg of polymerizate were discharged, an antioxidant solution was introduced therein in an amount of 0.4 mass.% based on polymer, degassed and dried on rollers at a temperature of 80°C (step 2). An antioxidant solution in an amount of 0.4 mass.% based on polymer and low-molecular weight polybutadiene Polyvest 130 at a dosage of 1.5% mass. (15 g per kg of polybutadiene) were added to the remaining polymer, stirred for 10 min, degassed and dried on rollers at a temperature of 80°C (step 3). Physical and mechanical properties, molecular weight characteristics of the polymers obtained at different steps are shown in Table 3.

Example 5

The process was similar to example 4 with the difference that 2,4,6-trichloro-

2.4.6-triphenoxycyclotriphosphazene (THF) was used as a branching agent at a dosage of 1.5 mol per 1 mol of neodymium. The modification process was continued for 60 minutes with constant stirring at a temperature of 80°C.

Physical and mechanical properties, molecular weight characteristics of the polymers obtained at different steps are shown in Table 3.

Example 6

The process was similar to example 4 with the difference that 2,4,6-trichloro-

2,4,6-triphenoxycyclotriphosphazene (THF) was used as a branching agent at a dosage of 1.8 mol based on neodymium (step 2). Polyvest EP-ST-E 60 was used as a plasticizer at a dosage of 0.8 mass.% (8 g per kg of polybutadiene), stirred for 5 minutes

Example 7

The process was similar to example 4, with the difference that the catalyst complex was prepared based on gadolinium versatate (GdV3). The dosage of the branching agent (HCF) was 1.5 mol per 1 mol of gadolinium. Liquid polyisoprene LIR 50 was used as a plasticizer in step 3 at a dosage of 0.8 mass.% based on polymer (8 g per 1 kg of polybutadiene)

Example 8

The process was similar to Example 5, with the difference that the prepared catalyst complex comprised tris-[bis(2-ethylhexyl)phosphate]neodymium (NdP3), butadiene (BD), and diisobutyl aluminum hydride (DIBAH); and ethyl aluminum sesquichloride (EASC) was used as a chlorinating agent. The molar ratio of BD:Nd:DIBAH:EASC components of the catalyst complex was 10:1:15:2.7. The time of aging the complex was 22 hours at a temperature of 25°C.

1.1 -Diphenyl-3, 3, 5, 5-tetramethylaminotriphosphoronitrile (DPP) was used as a branching agent in step 2 in an amount of 0.5 mmol per 1 mol of neodymium.

Example 9

The process was similar to Example 7, with the difference that the prepared catalyst complex comprised tris-[bis(2-ethylhexyl)phosphate]neodymium (NdP3), butadiene (BD), and diisobutyl aluminum hydride (DIBAH); and ethyl aluminum sesquichloride (EASC) was used as a chlorinating agent. The molar ratio of BD:Nd:DIBAH:EASC components of the catalyst complex was 10:1:15:2.7. The time of aging the complex was 22 hours at a temperature of 25°C.

1.1-Diphenyl-3,3,5,5-tetramethylaminotriphosphoronitrile (DPP) was used as a branching agent in step 2 in an amount of 1.5 mmol per 1 mol of neodymium. Liquid polyisoprene LIR 30 was used as a plasticizer in step 3 at a dosage of 1.0 mass.% based on polymer (10 g per 1 kg of polybutadiene).

Example 10

The process was similar to Example 8, with the difference that the prepared catalyst complex comprised praseodymium versatate (PrV3), butadiene (BD), and diisobutyl aluminum hydride (DIBAH) and ethyl aluminum sesquichloride (EASC). The molar ratio of BD:Nd:DIBAH:EASC component of the catalyst complex was 10:1:11:2.2. The time of aging the complex was 19 hours at a temperature of 22°C.

HCF was used as a branching agent at a dosage of 2.0 mol per 1 mol of praseodymium. Liquid polyisoprene LIR 30 was used as a plasticizer in step 30 at a dosage of 1.5 mass.% based on polymer (15 g per 1 kg of polybutadiene).

Example 11

The process was similar to example 8, with the difference that HCF was used as a branching agent at a dosage of 1.8 mol per 1 mol of neodymium (step 2). Liquid polybutadiene Polyvest EP-ST-E 80 functionalized with triethoxysilane with a degree of silanization of 80% was used as a plasticizer in an amount of 1.0 mass.% based on polymer (10 g per 1 kg of polybutadiene).

Example 12

The process was similar to Example 10 with the difference that liquid polybutadiene Polyvest EP-ST-E 80 functionalized with triethoxysilane with a degree of silanization of 100% was used as a plasticizer in an amount of 1.5 mass.% based on polymer (15 g per 1 kg of polybutadiene).

Example 13

The process was similar to example 10, with the difference that the dosage of the branching agent was 1.2 mol per 1 mol of neodymium, and maleinized liquid rubber Ricon 131 MA 10 was used as a plasticizer in an amount of 0.8 mass.% based on polymer (8 g per 1 kg of polybutadiene).

Example 14 The process was similar to example 8, with the difference that the dosage of the branching agent, DFF, was 5.0 mol per 1 mol of neodymium. Non-functionalized liquid polybutadiene Polyvest EP-ST-E 130 was used as a plasticizer in an amount of 2 mass.% based on polymer (20 g per 1 kg of polybutadiene).

Example 15

The process was similar to example 13, with the difference that thionyl chloride (SOCb) was used as a branching agent in an amount of 5 mol per 1 mol of neodymium.

Example 16

The process was similar to example 11 , with the difference that thionylchloride was used as a branching agent in an amount of 7.0 mol per 1 mol of neodymium, and maleinized liquid rubber Ricon 130 MA 8% was used as a plasticizer in an amount of 1.5 mass.% based on polymer (15 g per 1 kg of polybutadiene).

Example 17

The process was similar to example 14 with the difference that tin tetrachloride (SnCU) was used as a branching agent at a dosage of 2.5 mol per 1 mol of neodymium.

Example 18

The process was similar to example 14 with the difference that tin tetrachloride (SnCU) was used as a branching agent at a dosage of 5.0 mol per 1 mol of neodymium, and liquid polybutadiene Polyvest EP-ST-E 80 functionalized with triethoxysilane with a degree of silanization of 100% was used as a plasticizer in an amount of 5 mass.% based on polymer (50 g per 1 kg of polybutadiene). .

Example 19 The process was similar to example 9, with the difference that the catalyst complex was prepared based on tris-[(2-ethyl)hexanoate]neodymium (NdEh3), the dosage of DFF was 15 mol per 1 mol of neodymium (step 2), and the dosage of plasticizer, LIR 30, in step 3 was 0.5 mass.% based on polymer (5 g per 1 kg of polybutadiene). .

Example 20

The process was similar to example 18, with the difference that the catalyst complex was prepared based on tris-[bis(2-ethylhexyl)phosphate]neodymium, the dosage of tin tetrachloride used as a branching agent was 20 mol per 1 mol of neodymium, and Ricon 131 MA 10 was used as a plasticizer at a dosage of 0.5 mass.% based on polymer (5 g per 1 kg of polybutadiene).

Example 21

The process was similar to example 19, with the difference that the catalyst complex was prepared based on neodymium neodecanoate. The molar ratio of BD:Nd:DIBAH:EASC component of the catalyst complex was 10:1:13:2.0. The time of aging the complex was 19 hours at a temperature of 22°C. The dosage of the branching agent, S1CL4, was 1.0 mol per 1 mol of neodymium; Polyvest EP-ST-E MA75 was used as a plasticizer at a dosage of 0.5 mass.% based on polymer (5 g per 1 kg of polybutadiene).

Physical and mechanical properties, molecular weight characteristics of the polymers obtained at different steps are presented in Table 3.

Samples of the polymers obtained in examples 1-22 were tested in the formulation of rubber compositions (ASTM 3189), the test results are shown in Table 4. Table 2

Characteristics of liquid rubbers used according to the invention

* decoding of sample names see in the Note

** viscosity at 38°C MPa*s

Note:

Polyvest EP-ST-E 60 - triethoxysilane-functionalized liquid polybutadiene, degree of silanization 60% Polyvest EP-ST-E 80 - triethoxysilane-functionalized liquid polybutadiene, degree of silanization 80%

Polyvest EP-ST-E 100 - triethoxysilane-functionalized liquid polybutadiene, degree of silanization 100%

Polyvest 130 (S) - non-Functionalized Liquid Polybutadiene (S), contains an antioxidant

Polyvest EP-ST-E MA75 - Maleic Anhydride-Functionalized Liquid Polybutadiene

LIR 30 - liquid polyisoprene, degree of silanization 30%

LIR 50 - liquid polyisoprene, degree of silanization 50% Ricon 130 MA 8 - maleic anhydride-functionalized liquid polybutadiene with 8 maleic groups

Ricon 131 MA 10 - maleic anhydride-functionalized liquid polybutadiene with 10 maleic groups

Table 3

Properties of polymers

Table 3. Continuation

Note:

* - for the branching agent, the dosage is given in moles per 1 mol of lanthanide; for the plasticizer, the dosage is given in mass.% based on 100% polymer Abbreviations used in Table 3:

NdP3 - tris-[bis(2-ethylhexyl)phosphate]neodymium

NdV3 - neodymium neodecanoate

GdV3 - gadolinium versatate

NdEh3 - tris-[(2-ethyl)hexanoate]neodymium

DEAC - diethyl aluminum chloride

EASC - ethyl aluminum sesquichloride

HCP - 2,2,4,4,6,6-hexachloro-l,3,5-triaza-2,4,6-triphosphorine;

TCP - 2,4,6-trichloro-2,4,6-triphenoxycyclotriphosphazene;

DPP - 1.1- diphenyl-3, 3, 5, 5-tetramethylaminotriphosphoronitrile;

SiCL4 - silicon tetrachloride SOC12 - thionylchloride

D ML 2/1 (%) - an increase in viscosity of polymer obtained in step 2 in comparison with polymer obtained in step 1, calculated by the formula presented in the section "Disclosure of the invention"

D tg5 1200% 2/1 (%) - a change in branching index of polymer obtained in step 2 in comparison with polymer obtained in step 1, calculated by the formula presented in the section "Disclosure of the invention"

D ML 3/2 (%) - a drop of Mooney viscosity of a branched polymer obtained in step 2 after introducing a plasticizer (step 3), calculated by the formula presented in the section "Disclosure of the invention"

D tg6 1200% 3/2 (%) - a change in branching index of polymer obtained in step 3 in comparison with polymer obtained in step 2, calculated by the formula presented in the section "Disclosure of the invention" Table 4

Plasto-elastic properties of rubber compositions

Table 4. Continuation

As can be seen from Table 4, the proposed method for preparing branched poly dienes can improve the processability of rubber compositions by 6-10% (based on Mooney viscosity index) and the distribution of a filler in the polymer matrix (evaluated by the Payne Effect parameter). When using only modifiers without a plasticizer, a desired range of branching index tgb (1200%) from about 4.7 to about 5.3 is not achieved, and, therefore, the processability of rubber compositions and the distribution of a filler in such polymers are worse.

Thus, the technical solution according to the invention allows the production of a branched polydiene characterized by a Mooney viscosity from about 40 to about 49 MU and a branching index, as characterized by a mechanical loss angle tangent tg6 (1200%), from about 4.7 to about 5.3. The polydiene prepared according to the invention has an improved processability, an improved distribution of the filler in the polymer matrix, and rubber compositions based on it are characterized by improved elastic-hysteresis properties (namely, Mooney viscosity ML(l+4), MU, a Payne effect A(G'1%-G'50%), kPa, tg560°C at 10% deformation).

Claims

1. A method for producing a branched polydiene by polymerization of a conjugated diene, comprising: preparing a catalyst complex comprising a lanthanide compound, an organoaluminum compound, a conjugated diene and a halogen-containing component; polymerizing the conjugated diene in the presence of said catalyst complex; performing post-polymerization modification with at least one branching agent selected from the group consisting of halogen-containing compounds, phosphorus- nitrogen compounds or mixtures thereof; termination; introducing at least one plasticizer into the polymer, wherein the plasticizer is a low molecular weight polymer with a molecular weight of from 1500 to 5000 g/mol degassingand drying the polymer.

2. The method according to claim 1 characterized in that the branching agent is halogen-containing compound, selected from the group, comprising thionyl chloride, diphenyltin dichloride, phenyltin trichloride, triphenyltin chloride, dibutyltin dichloride, butyltin trichloride, tin tetrachloride or silicon tetrachloride, preferably tin tetrachloride, methyltin trichloride, ethyltin trichloride, butyltin trichloride or silicon tetrachloride, most preferably tin tetrachloride or silicon tetrachloride.

3. The method according to claim 1 characterized in that a mole ratio of the halogen-containing compound, which is selected as the branching agent, to lanthanide is from 1.0 to 20, preferably from 2.0 to 15; the mole ratio most preferably is from 5.0 to 10.0.

4. The method according to claim 1 characterized in that the branching agent is the phosphorus-nitrogen compound with a chemical structure based on repeating units of (-P=N-)_n, wherein n is an integer from 3 to 24; preferably, the branching agent is chlorine-containing phosphorus-nitrogen compounds comprising from 2 to 6 chlorine atoms.

5. The method according to claim 4 characterized in that the branching agent is chlorine-containing phosphorus-nitrogen compound, selected from the group, comprising 2,2,4,4,6,6-hexachloro-l ,3,5-triaza-2,4,6-triphosphorine; 2,4,6-trichloro- 2,4,6-triphenoxycyclotriphosphazene; 2,2,4,4-tetrachloro-6,6- dimethylmercaptocyclotriphosphazatrien or 4,4,6,6-tetrachloro-l,3,5-triaza-2,4,6- triphosphocyclohexa- 1 ,3 ,5-triene-2, 2-diamine.

6. The method according to claim 1 characterized in that a dosage of the phosphorus-nitrogen compound selected as the branching agent is from 0.5 to 15.0 mol per 1 mol of lanthanide, preferably from 1.0 to 5.0 mol per 1 mol of lanthanide.

7. The method according to any one of claims 1 to 6 characterized in that the plasticizer is a non-functionalized low-molecular weight polybutadiene, polybutadiene functionalized with maleic anhydride or triethoxy silane, non-functionalized low- molecular weight polyisoprene, or polyisoprene functionalized with maleic anhydride, preferably non-functionalized low-molecular weight polybutadiene or polybutadiene functionalized with maleic anhydride or triethoxy silane.

8. The method according to any one of claims 1 to 7 characterized in that a dosage of the plasticizer is from 0.5 to 5.0 mass.% based on polymer, preferably from 0.7 to 2.0 mass.%, most preferably from 0.8 to 1.5 mass.%.

9. The method according to any one of claims 1 to 8 characterized in that the lanthanide compound in a catalyst complex is neodymium carboxylate or organophosphate.

10. The method according to claim 9 characterized in that the lanthanide compound in the catalyst complex is neodymium neodecanoate, tris-[bis(2- ethylhexyl)phosphate]neodymium or a mixture thereof.

11. The method according to any one of claims 1 to 10 characterized in that the organoaluminum compound is a compound selected from the group including trialkyl aluminum, triphenyl aluminum or dialkyl aluminum hydrides, alkyl aluminum dihydrides, in particular, trimethyl aluminum, triethyl aluminum, tri-n-propyl aluminum, triisopropyl aluminum, tri-n-butyl aluminum, triisobutyl aluminum, tri-tert- butyl aluminum, triphenyl aluminum, trihexyl aluminum, tricyclohexyl aluminum, trioctyl aluminum, diethyl aluminum hydride, di-n-propyl aluminum hydride, di-n-butyl aluminum hydride, diisobutyl aluminum hydride, dihexyl aluminum hydride, diisohexyl aluminum hydride, dioctyl aluminum hydride, di-isooctyl aluminum hydride, phenyl ethyl aluminum hydride, phenyl-n-propyl aluminum hydride, phenyl isopropyl aluminum hydride, phenyl-n-butyl aluminum hydride, phenyl isobutyl aluminum hydride, benzyl ethyl aluminum hydride, benzyl-n-butyl aluminum hydride, benzyl isobutyl aluminum hydride, and benzyl isopropyl aluminum hydride, preferably triethyl aluminum, triisobutyl aluminum, diisobutyl aluminum hydride or a mixture thereof.

12. The method according to any one of claims 1 to 11 characterized in that the conjugated diene is a compound selected from the group including 1,3-butadiene, isoprene, 2, 3-dimethyl-l, 3-butadiene, piperylene, 2-methyl-3 -ethyl- 1, 3-butadiene, 3- methyl-l,3-pentadiene, 2-methyl-3-ethyl-l,3-pentadiene, 3-methyl-l,3-pentadiene, 1,3- hexadiene, 2-methyl- 1,3-hexadiene, 1,3-heptadiene, 3-methyl-l,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, and 2-methyl-3-isopropyl-l, 3-butadiene, preferably 1,3-butadiene and isoprene.

13. The method according to any one of claims 1 to 12 characterized in that the catalyst complex used for polymerization comprises lanthanide compound (A), conjugated diene (B), organoaluminum compound (C) and halogen-containing component (D) in a molar ratio of (A):(B):(C):(D) of l:(5-30):(8-30):(l.5-3.0), wherein molar quantity of the lanthanide compound (A) is counted on molar quantity of the lanthanide.

14. A branched polydiene prepared by a method according to any one of claims

1 to 13.

15. A branched poly diene characterized by a Mooney viscosity of from 40 to 49 Mooney units and a branching index expressed in a mechanical loss angle tangent tg6 (1200%) between 4.7 and 5.3, as measured using a variable shear amplitude in an amplitude range from 10 to 1200%, a frequency of 0.1 Hz, and a temperature of 100°C.

16. The branched polydiene according to claim 14 or claim 15 characterized by a Payne effect A(G'1%-G'50%), kPa, Tan6 60°C at 10% deformation.

17. A rubber mixture based on polydiene according to any one of claims 14 to

16.