WO2017116263A1

WO2017116263A1 - Method for producing rubbers having reduced cold flow

Info

Publication number: WO2017116263A1
Application number: PCT/RU2015/000948
Authority: WO
Inventors: Irina Vladislavovna ELISEEVA; Svetlana Viktorovna TURENKO; Pavel Sergeevich LEMPORT; Airat Filipovich NAGORNYAK; Alena Vitalievna GUTSAL
Original assignee: Public Joint Stock Company "Sibur Holding"
Priority date: 2015-12-29
Filing date: 2015-12-29
Publication date: 2017-07-06
Also published as: RU2686097C1

Abstract

The invention relates to the production of modified rubbers having reduced cold flow, and rubber mixtures comprising such modified rubbers. A method for preparing rubbers with a reduced cold flow selected from polybutadiene rubber, butyl rubber, and polyisobutylene rubber comprises adding a suspension of layered silicate to a polymerizate formed during preparation of the rubber by polymerization, wherein the silicate is added to the polymerizate in the form of a suspension when a monomer conversion rate reaches a target conversion for said polymerization process. The invention can be used in the industry of synthetic rubbers, and the produced modified rubbers can be used both individually and as a component of composite elastomeric materials used for the production of mechanical rubber goods (MRG) and tires with improved performance characteristics.

Description

METHOD FOR PRODUCING RUBBERS HAVING REDUCED COLD FLOW

FIELD OF THE ART

The invention relates to the field of the manufacture of general and special- purpose rubbers having a controlled cold flow. In particular, the invention relates to the production of modified rubbers having reduced cold flow, and rubber mixtures comprising such modified rubbers. The invention also can be used in the industry of synthetic rubbers, and the produced modified rubbers can be used both individually and as a component of composite elastomeric materials used for the production of mechanical rubber goods (MRG) and tires with improved performance characteristics.

BACKGROUND

Butadiene rubber, polyisobutylene rubber, and butyl rubber are widely used in the manufacture of tires and mechanical rubber goods (MRG) thanks to the complex of their unique characteristics. However, many grades of said rubbers have an increased cold flow, which results in certain problems in isolation, storage, and transportation thereof, in particular, an increased cold flow at normal temperature and relatively low loadings complicates the isolation and storage not only of rubbers as such but also, in some cases, resin mixtures based thereon.

Polyisobutylene rubbers and butyl rubbers have a high performance under exposure to various factors, which is provided by their good resistance to aging, mineral oils, acids, and chemical media (except hydrocarbons), ozone, and water, s well as by their ultralow gas-, steam-, and water permeability. In addition, vulcanization of said rubbers improves their elasticity, electrical resistivity, and resistance to abrasion wear, acids, and heat-aging. Thanks to these properties, said elastomers are broadly used in industry.

Butyl rubber is used in the manufacture of automobile inner tube, tire innerliner, hoses, conveying belts, for insulating electric cables, encasing reservoirs, etc. It is known that butyl rubber is characterized by an increased cold flow, which poses problems in isolation, drying, packing and transportation thereof (P.A. Kirpichnikov et al./ Khimiya i tekhnologiya sinteticheskogo kauchuka [Chemistry and technology of synthetic rubbers], p.322, paragraph 2; Oilman's Encyclopedia of Industrial Chemistry. Rubber, 5. Solution Rubbers, Vol.31 , p.671 , col.2, paragraph 2).

High molecular-weight polyisobutylene is used in the manufacture of chemically resistant sheet and water-proof materials, rubbery fabrics, electric insulating materials, sealants, and adhesive tapes. Hydrocarbon solutions and aqueous dispersions of polyisobutylene are used as glues in the manufacture of artificial fur, suede, and other textile-based materials, and as impregnating compositions in the production of paper and asbestos cardboard. (see http://www.performancechemicals.basf.com/ev/internet/polyisobutene/en content/EV3/ polyisobutene/applications; http://adhesives.specialchem.com/tech- library/article/polyisobutylene-as-a-base-polymer-and-modifier-for-adhesives-and- sealants).

Polyisobutylenes are used in chemical industry for coating or insulation of various vessels, tubes, sleeves, and the like See http://www.stroitelstvo- new.ru/kauchuk/sintez.shtml;

http://www.siginsulation.co.uk/show_prod.asp?ProdID=2600&CatID=20&SubCatID= 127).

However, some grades of polyisobutylenes have an increased flow properties. Introduction of active additives (for example, such as carbon black, black lead, talc) increases the strength and hardness of compositions, reduces flow, while decreasing resistance of the polymer to light and atmospheric oxygen (See http://bibliotekar.ru/spravochnik-52/5.htm).

Polybutadiene rubbers are used in large amounts in mixtures with other elastomers to provide tire rubbers with good hysteresis characteristics and wear resistance and improve resistance to cracking. Polybutadiene rubber improves cold- resistance and heat-aging of MRGs and tires. Polybutadiene rubbers are widely used in the manufacture of auto tires and conveying belts, insulation of electric cables, cold- resistance articles, and articles with a high dynamic strength and wear resistance, etc. (P.A. Kirpichnikov et al./ Khimiya i tekhnologiya sinteticheskogo kauchuka [Chemistry and technology of synthetic rubbers], p.293, paragraph 2 from the bottom). However, an insufficient branching of molecular chains and a low thermal plasticity determine a high cold flow of these rubbers during storage and transportation (Ullman's Encyclopedia of Industrial Chemistry. Rubber, 5. Solution Rubbers, Vol.31, p.659, col.l, paragraph 1, lines 21-26).

A common shortcoming of butadiene rubbers (preferably prepared on neodymium-containing catalyst complexes) polyisobutylene rubbers, and butyl rubbers is their low green strength and high cold flow. In the prior art there are various approaches in solving this problem.

Thus, patent document WO 2004/003038 Al discloses a method of improving the balanced between improved processability and reduced cold flow of butyl rubber (BR), comprising producing butyl rubber with an increased (up to 2.5 mol%) content of C₄-Ci₄ multiolefin monomer, most frequently, isoprene. The technical result is achieved by increasing the content of C₄-Ci₄ multiolefin monomer and the use of 2,4,4-trimethyl-l -pentene (TMP) as a polymerization regulator. The cold flow of samples was evaluated by an increase in the area under the relaxation curve in measurements of Mooney viscosity compared to the area under the relaxation curve for standard butyl rubber (a reference sample). The BR technology according to the invention provides an increase in cold flow three and more times. A shortcoming of this method relative to the standard method for producing BR consists in an increased content of C₄-Ci₄ multiolefin monomer (most frequent isoprene) in the copolymer, which negatively affects heat-, ozone-, and thermal-resistance of BR. Application WO 02/016452 Al discloses another approach, wherein to improve the processability and reduce the cold flow of butyl rubber, in addition to a polymerization regulator (2,4,4- trimethyl-l-pentene), the butyl rubber is branched by using bifunctional monomers, in particular divinylbenzene (DVB). The technical result of said technical solution is in a possibility to vary rheological and cohesion properties of rubber by its branching controlled by a molecular-weight regulator. The technical result is achieved by adding a bifunctional monomer added to a mixture of monomers before the polymerization process and by controlling the intensity of the reaction by a polymerization regulator (2,4,4-trimethyl-l -pentene (TMP)) and adjusting the optimal temperature. The cold flow of the obtained butyl rubber samples, which was evaluated by a change in the area under the relaxation curve, decreases by 5-7%. One of the main shortcomings of the method is the use of DVB as a cross-linking agent. In copolymerization, divinylbenzenes act as a cross-linking agent, wherein the efficiency of their isomers increases in the following series: o-divinylbenzene < w-divinylbenzene < p- divinylbenzene. Since technical grades of divinylbenzenes can comprise 20-25, 50-60, and about 80% of meta- and >ara-isomers in a mixture with ethylvinylbenzene and substantially do not have an analytically stable composition of isomers, the butyl rubber produced by the disclosed method will not have stable output characteristics [Entsiklopediya polimerov [Encyclopedia of polymers] v.l , M., 1972, pp.695; Kirk- Othmer encyclopedia, v. 21 , N. Y., 1983, p. 796]. It should be noted that branching of BR, while improving its processing characteristics, may negatively affect the performance properties of vulcanized rubbers.

A reduction in the cold flow of cis-l ,4-polybutadiene is known to be achieved by using various branching agents of the post-polymerization modification, for example, chlorides of phosphorus, tin, silicon, and other compounds [L. Friebe, 0. Nuyken, W. Obrecht "Neodymium Ziegler-Natta catalysts and use thereof, 2001 ; p.56]. However, these methods also lead to a significant undesirable change in the polymer microstructure.

Another solution is disclosed in patent RU 2442796 CI (see p.4, lines 2-25), wherein the authors try to reach a reduction in the cold flow of butadiene rubber SKD- ND to values of less than 25 mm/h by a modification of the rubber with unsaturated polyketones. The modification is carried out at a butadiene- 1,3 conversion rate of not less than 95%. Low molecular-weight unsaturated polyketones used as a modifier are liquid opligomers. A shortcoming of the method consists in that a polyketone molecule comprises a large number of double bonds and oxygen-containing functional groups, which can result in a reduction in heat-, thermal-, weather-, and ozone-resistance of the rubber and articles based thereon.

Another technical solution to reduce the cold flow of polybutadiene rubber is disclosed in RU 2087489 CI (see RU 2087489 CI, abstract, p. l ; pp.3-4, Examples 2 and 6). According to this solution, cis-l,4-polybutadiene is prepared by polymerization of butadiene- 1,3 in an aromatic solvent in the presence of a rare-earth metal-based Ziegler-Natta catalyst. Upon completion of the process, the cis-l,4-polybutadiene polymerizate is mixed with a polyhexene-1 solution in an aromatic solvent. The optimal dose of polyhexene is 5-20 parts by weight per 100 parts (phr) of polybutadiene and allows the control of elastomer plasticity and a reduction in the cold flow of polybutadiene to less than 7 mm/h. A shortcoming of the claimed method is a need for polyhexene-1 with given characteristics, which in practice can complicate the method and increase the costs of the production process. In addition, the addition of polyhexene-1 can deteriorate physico-mechanical properties of the final product due to a reduction in the portion of polybutadiene in the mixture and, as a result, a reduction in the density of vulcanization network since polyhexene does not comprise double bonds providing its co-vulcanization with the molecules of butadiene rubber.

Document RU 2127280 CI discloses another method for producing cis-1,4- polybutadiene with a decreased cold flow (see RU 2127280, p.3, col. l , lines 32-62; p.6, Table 2). The method comprises polymerization of butadiene on a catalyst complex formed in the presence of diene (butadiene, piperylene, isoprene), wherein the catalyst complex consists of a carboxylate of a rare-earth element, halogen-containing organoaluminum compound and organoaluminum compound. The halogen-containing compound is added only in the process of preparing the catalyst complex or additionally in the polymerization process at a monomer conversion rate of 50-85%. In addition, in the polymerization process, the indicated chloro-containing compound is replaced with a compound selected from the group of including: benzyl chloride, tert- butyl chloride, ethyl chloride, propyl chloride, isobutyl chloride, ethylaluminum sesquichloride (EASC), isobutylaluminum sesquichloride, chloranil, followed by aging the reaction mass.

The produced polymers have a reduced plasticity and cold flow, and vulcanizates based thereon exhibit high physico-mechanical parameters. Thus, changing the amount of the added chloro-containing compound and the time of aging the reaction mass after addition of the modifier, the cold flow can be reduced from 31.3 mm/h (by using EASC) to 1.05 mm/h. Said patent provides no information about molecular weight characteristics and polydispersity of the disclosed rubbers, which does not allow an unambiguous conclusion for the cause of such a significant change in the cold flow of the rubbers. However, it is obvious that such a significant change in the composition of the initiation system leads to changes in the micto- and macro- structural characteristics of the obtained rubber, which, on the one hand, allows a reduction in cold flow, and, on the other hand, has an adverse effect on some performance characteristics.

Patent RU 2099359 CI discloses a method for producing cis-l,4-diene rubber by polymerization of diene in an aromatic solvent by using a catalyst comprising Neodymium-containing compounds and triisobutylaluminum (see RU 2099359, p.5, claim 1 ; p.7, Table 2). The proposed method characterized in that, a toluene solution of quinol ether of the formula:

wherein R is tert-butyl,

is added to the polymerizate upon completion of the polymerization process or to the prepared rubber at the following steps of the processing process, in an amount of 0.01 to 0.1 wt.% based on monomer.

The addition of said compound allows a reduction of the cold flow from 28.6 mm/h to 6 mm/h.

A shortcoming of the method consists in branching of polymer chains, partial cross-linking of the rubber comprising said compound during processing, and contamination of a recycle solvent or wastewaters with the modifier or its degradation products.

The above-disclosed approaches in reduction of the cold flow of rubbers do not mention an improvement of processability without modifying micro- and macro- structures thereof, an improvement of barrier characteristics, and/or an increase in fatigue strength and weather resistance of vulcanized rubbers based thereon.

The prior art teaches filling rubbers with layered silicates at the step of preparing rubber mixtures to improve their physico-mechanical properties. Referring to the prior art reports in the field concerning the use of layered silicates in the polymer chemistry, clays are used mainly to improve the barrier properties of plastics and rubbers, for example gas impermeability. There are also reports about an improvement of processability of rubbers and rubber mixtures filled with layered silicates (clays) and an increase in their flex-crack resistance.

It has been proved that an addition of layered silicates (such as, for example, organoclays) to rubber can improve weather resistance and processing characteristics of the rubber and rubber mixtures based thereon, thanks to anisotropy of the clay particles [Sadhu S, Browmick A.K./ Unique rheological behavior of rubber based nanocomposites.// J. Polymer Sci., Part B: polymer Phys., 43, 1859, 2005].

Thus, patent US 8476352 B2 discloses that an addition of organoclay Cloisite Na added to an elastomer in an amount of 5 to 10 wt.% directly at the step of preparing a rubber mixture improves the processibility of the rubber mixture and increases the air impermeability of vulcanized rubbers.

The method disclosed in US 2005/0282948 comprises in situ copolymerization of monomers in the presence of organoclay. The described method relates to rubbers produced by anionic solution copolymerization of two monomers selected from butadiene, isoprene, styrene, etc. A main advantage of organoclay-containing polymers is in improved mechanical properties and increased barrier characteristics. However, a main shortcoming of this method is the addition of organoclays at the earlier steps of the polymerization process, which has an adverse effect on the activity of the initiation system, since it increases its consumption and requires adjustment of its composition. In addition, in situ anionic polymerization in the presence of organoclays leads to significant undesirable changes in the macro- and micro-structure of rubbers [Maiti M., Bhattacharya M, Bhowmick A. K./ Elastomer Nanocomposites// Rubber Chemistry and Technology. - 2008. - V. 81. - N.3. - P. 404, 418; M. Liao, W. Shan, J. Zhu, Y. Li, and H. Xu/ J. Polym. Sci., Part B: Polym. Phys. 43, 1344, 2005; Z. Zhang, L. Zhang, Y. Li, and H. Xu/ Polymer 46, 129, 2005].

Patent document WO2007/109877 (Al ) discloses a method of in situ copolymerization of an C4-C8isoolefin monomer and a C4-C14 multiolefin monomer in the presence of organoclay. The main purpose of the present invention is to increase barrier characteristics of butyl rubber or bromobutyl rubber. The method comprises dispersing organoclay Cloisite^® in methylchloride in an amount of 5-7 wt.% from an expected amount of a butyl rubber resulted from the copolymerization process, performing the copolymerization process until the conversion rate reaches 75%, and optionally bromating. Said method provides a polymer comprising an effectively intercalated and partially exfoliated organoclay. The resultant polymers exhibit

8 2

improved barrier characteristics, their air permeability is 2.7* 10^" (cm /atm/C) against 3.4* 10^"8 (cm²/atm C) in the control sample of organoclay-free rubber. This method of polymerization requires the use of exclusively tertiary amine-modified clays. Given a possible negative effect of moister contained in clay on molecular-weight characteristics of a polymer and on the activity of an initiation system, clays must be pretreated (dried) prior to be used. In addition, this invention cannot be applied to the method of synthesis of butyl/halobutyl rubber at temperatures more than minus 90°C.

Filling of rubbers with layered silicates at the step of preparing rubber mixtures improves the above-mentioned specific technical characteristics of vulcanized rubbers. However, this method of filling rubbers does not address the problem of their cold flow under storage and transportation.

The prior art discloses various methods of chemical and physical modification to reduce the cold flow of 1,4-cis-butadiene and butyl rubbers by addition of special compounds both to a reaction mass at the step of synthesis of rubber and to a polymerizate at high conversion rates of monomer(s) or after polymerization and by changing the composition of an initiation system. The main principle of chemical modification of rubbers consists in changing of their micro- and macro-structure, which may further negatively affect the processing characteristics of an article. Methods of physical modification allow a directed action on the cold flow of a polymer, without changing the micro- and macro-structure thereof.

In addition, it is advisable that modification of 1 ,4-cis-butadiene, butyl, and polyisobutylene rubbers provides not only a reduction in their cold flow but also an improvement of other important technical properties of the rubbers and articles based thereon.

Thus, there is a need for new methods of a directed modification of 1,4-cis- butadiene, butyl, and polyisobutylene rubbers to reduce their cold flow without changing their micro- and macro-structural characteristics which additionally improve other processing characteristics of tire vulcanized rubbers and MRG based on such rubbers.

SUMMARY OF THE INVENTION

The technical objective of the present invention is to develop a method of a directed physical modification of 1,4-cis-butadiene, butyl, and polyisobutylene rubbers to reduce their cold flow without changing their micro- and macro-structural characteristics, while additionally improving other processing characteristics of tire vulcanized rubbers and MRG based on such rubbers.

The posed objective is addressed by means of a controlled physical modification of 1,4-cis-butadiene, butyl, and polyisobutylene rubbers and other elastomers characterized by a high cold flow, according to the claimed invention. One embodiment of the invention provides rubbers, in particular selected from the group including: polybutadiene rubber, butyl rubber, and polyisobutylene rubber, produced by the method comprising adding a suspension of layered silicate to a polymerizate formed in the polymerization process during preparing the rubber, followed by stabilization, degassing, separation, and drying the resultant product, at the monomer conversion rate of not less than (0.95-1.0) x X(%). Herein, X is a target conversion for the selected polymerization process providing the obtainment of a corresponding rubber. The target conversion as used herein means a predetermined conversion stated according to the processing method for preparing rubber.

Another embodiment of the invention provides modified rubbers with reduced cold flow, prepared according to the present invention.

In addition, the present invention provides rubber mixtures for the manufacture of articles comprising one or more of such modified rubbers, and articles made of said rubber mixture. In some embodiments of the present invention, said article is a tire element, in particular tire sidewall, tire tread, or tire innerliner.

The invention provides rubbers with improved processing properties, first of all, a reduced cold flow, and vulcanized rubbers based thereon having improved processing properties. This is resulted from the uniform distribution of layered silicates in a polymerizate, which is accompanied with intercalation and partial exfoliation of the silicate particles throughout the polymer matrix, and the formation of the framework limiting the flow of the polymer macromolecules under storage and transportation, on the one hand, and with improving the barrier and other physicomechanical properties of the vulcanized rubbers, on the other hand.

The resultant modified rubbers are useful, in particular, in the manufacture of mechanical rubber goods (MRG) and auto tires (for trucks, agricultural equipment, and passenger cars). Vulcanized rubbers for MRGs and tires, which are produced by using such rubbers, exhibit reduced gas permeability, improved processability, and increased fatigue strength, which ensures an increased reliability and life time of an article as a whole.

BRIEF DESCRIPTION OF DRAWINGS

Fig.1 shows a dependence of the cold flow of rubber SKD-ND on the content and type of layered silicate. DETAILED DESCRIPTION OF THE INVENTION

Some terms and concepts as used in the present disclosure have the meanings as defined below.

The term "polymerizate" means a reaction mass based on a hydrocarbon solvent, having partially or completely polymerized monomer(s). Depending on the required type and properties of the final product, the monomer conversion rate may vary from 5 to 99%.

The term "rubber solution" means a solution of rubber in a hydrocarbon solvent. Said solution is prepared by grinding the rubber and dissolving thereof in a hydrocarbon solvent under stirring.

The term "parts by weight per 100 parts of rubber (phr)" used in the text of the present invention means the number of parts of any component of a rubber mixture in terms of 100 parts of the rubber, and is a measurement unit accepted in the art.

As indicated above, the main embodiment of the invention provides physical modification of 1 ,4-cis-butadiene, butyl, and/or polyisobutylene rubbers in the process of their production by addition of a suspension of layered silicate to a polymerizate at a monomer conversion rate of not less than (0.95-1.0) x X(%), preferably (0.95-0.98) x X(%). X is a target (i.e. a preset conversion rate determined by the process conditions) conversion achieved in the polymerization process when preparing a selected rubber.

Thus, for example, in the synthesis of 1 ,4-cis-butadiene rubbers, a target conversion X is (95-100)%, more preferably from 99 to 100%. In solution polymerization of polyisobutylene and butyl rubbers, a target conversion X is (5- 100)%, more preferably from 10 to 80%, and more preferably from 20 to 40%.

When the conversion rate is less than the indicated range, the addition of a layered silicate can lead to significant changes in the micro- and macrostructures of rubber, initiate chain-transfer processes or cause a premature termination of the polymerization process. The latter may be excluded by special preparation of layered silicate, for example, careful drying, which increases the cost of the process. When the conversion rate is higher than the indicated range, it may complicate the distribution of a clay suspension throughout a polymerizate due to an increased viscosity of the medium. In addition, in higher conversion rates, the possibility of the polymerization process in the interlayer space of clays is minimized or excluded, which does not provide additional intercalation and exfoliation of clay particles. In addition, in some cases, it is difficult to increase the conversion rate because of the approximation to the maximum achievable values under preset conditions of polymerization.

This method of modification is useful in the preparation of linear and branched 1 ,4-cis-butadiene rubbers, polyisobutylene rubbers, and butyl rubbers characterized by an increased cold flow, for example, such as 1,4-cis-polybutadiene rubbers SKD-ND, polyisobutylene rubbers of grades P-85 (PIB HRD-800), P-200 (PIB HRD-950), ΡΓΒ- 1300 etc., including butyl rubbers characterized by lower molecular weight and/or Mooney viscosity, whose cold flow is more pronounced, for example, BK-1570C (IIR 1570). In addition, it is more preferable to apply physical modification with layered silicates to linear solution 1 ,4-cis-polybutadiene rubbers produced by the ionic coordination polymerization method in the presence of Neodymium, cobalt and other catalysts, wherein the content of 1 ,4-cis-monomers is at least 95 wt.%; linear butyl rubbers with the content of a polyolefin monomer (as a rule, isoprene) is from 1.0 to 2.5 wt.%, and polyisobutylene rubbers.

The fundamental principles of the production of all the above-recited rubbers are disclosed in details in the following documents (P.A. Kirpichnikov et al./ "Khimiya i tekhnologiya sinteticheskogo kauchuka" [Chemistry and technology of synthetic rubbers], pp.322-324, paragraphs 2.9, 2.9.1 and 2.9.2; Ullman's Encyclopedia of Industrial Chemistry. Rubber, 5. Solution Rubbers, Vol.31, pp.658-663, 671-676], each of which is fully incorporated herein by reference.

Rubbers subjected to the modification according to the present invention relate to the group of rubbers produced by the solution polymerization method. Thus, synthetic cis-butadiene rubber SKD-ND comprising at least 96% of 1 ,4-cis-monomers is a polymerization product of butadiene in a solution in the presence of ionic coordinate catalytic systems. The polymerization medium is formed by a hydrocarbon solvent.

Butyl rubber may be produced by cationic solution copolymerization of isobutylene with olefin monomers, usually with isoprene, in a hydrocarbon solvent in the presence of organoaluminum catalyst at temperature of from minus 100°C to minus 55°C [US 6630553 B2 which is fully incorporated herein by reference] and at temperature of from minus 90°C to minus 35°C in the presence of a catalytic system containing a boron organic compound and an organic acid [see WO 03037940 Al ; WO 02059161 Al which is fully incorporated herein by reference].

Copolymers of isobutylene with olefins (butyl rubbers) can be also prepared according to patent RU 2124527 CI which is fully incorporated herein by reference (see abstract, p.2), by polymerization and copolymerization of isobutylene in a hydrocarbon solvent in the presence of a Lewis acid and a modifier. The Lewis acid is either a complex of titanium tetrahydrochloride and triisobutylaluminum in combination with a modifier or a complex of titanium tetrahydrochloride with alkyl aluminum halide. The modifier is 2,6-di- r/-butyl or 4-methylphenol or 2,2- methylene-bis(4-methyl-6-ter/-butylphenol), or tetraethoxysilane, or boron trifluoride.

High molecular weight polyisobutylenes can be prepared by polymerization of isobutylene in a hydrocarbon solvent in the presence of Friedel-Crafts catalysts at temperature of 0°C to minus 100°C (See WO 03062284 A2 which is fully incorporated herein by reference).

Thus, according to the claimed method, chemical modification may apply to rubbers of the group of 1 ,4-cis-butadiene, polyisobutylene, and butyl rubbers produced in a solution in the presence of various catalyst systems described in literature, including patent sources, in particular the above-cited sources.

A physical modification with layered silicates according to the claimed method is also possible in synthesis of various chemically modified grades of 1 ,4-cis- butadiene, polyisobutylene, and butyl rubbers, for example, solution polybutadiene grades SKD-ND (BR- 1243 Nd B), SKD-6 (SDK-6-EF), SKD-7 (SKD-Nd-EF-40), Buna CB24, Nd-PBR, bromated butyl rubbers, and others.

The amount of a polymer in a rubber solution or in a polymerizate can range between 3 and 75 wt.%, preferably 5 and 50 wt.%, most preferably 7 and 20 wt.%.

The layered silicate may be selected from modified and non-modified silicate materials with a particle size not more than 100 nm. For example, layered silicates may be clays, in particular smectite clays, for example, montmorillonites, hectorites, serpentinites, etc., in particular non-modified bentonite (montmorillonite). In another embodiment, there are useful layered silicates modified with queternary ammonium salts, so-called organoclays. The non-modified montmorillonite may be layered silicate "Bentonit" produced by OOO "Altaiskaya syrievaya kompaniya" (Russia) and the like. Useful organoclays are organoclays available under tradenames such as Dellite^® (Dellite^®72T; Dellite^®67G, etc.) produced by Laviosa Chimica Mineraria S.p.A. (Italy); Cloisite^® (Cloisite^®10A, Cloisite^®15A, Cloisite^®20A, Cloisite^®30A, Cloisite^®93A, etc.) produced by Rockwood (US); Metamon™, etc.

Preferably, layered silicate is selected from the group consisting of montmorillonite clays, kaolin clays, chloritic clays, hydrous micas, and alternating- layer minerals.

The dispersion system used for the preparation of a layered silicate suspension may be selected from aliphatic, alicyclic, aromatic hydrocarbons, chlorinated hydrocarbons, and mixtures thereof in various ratios. In particular, suitable hydrocarbons are aliphatic hydrocarbons, such as pentane, isopentane, hexane, heptane, cycloheptane, cyclohexane, methylcyclohexane, cycloheptane, isooctane, n- octane, hexane-heptane hydrocarbon fraction in various hexane/heptane ratios; aromatic hydrocarbons, such as benzene, toluene, xylene, ethylbenzene, diethylbenzene, isobutylbenzene; petroleum ether; inert halogenated C1-C4- hydrocarbones, for example, dichloromethane, ethylchloride, methylene chloride, chloromethane.

In case of modification of 1 ,4-cis-polybutadiene rubber, the most suitable medium for the preparation of a layered silicate suspension is hexane, heptane, cyclohexane, and toluene, or a mixture thereof. In the case of modification of butyl rubber and polyisobutylene rubber, most suitable medium for the preparation of a layered silicate suspension may be such hydrocarbons as pentane, isopentane, and a mixture thereof, xylene, toluene, and various inert halogenated C2-C₅-hydrocarbones used as a polymerization medium. As a dispersion medium, there are also useful synthetic and mineral oils, namely, aromatic oils, naphthene and paraffin oils, such as, for example, MES (Mild Extraction Solvate), TDAE (Treated Distillate Aromatic Extract), RAE (Residual Aromatic Extract), DAE (Distillate Aromatic Extract). Examples of used oils can be products known under tradenames Norman, Vivatec (500, 200), Enerthene 1849-1 , Nytex (4700, 8450, 5450, 832), Tufflo (2000, 1200), etc. In addition, a layered silicate suspension can be prepared by using a prepared polymerizate, as a dispersion medium. Preferably, the polymerizate is characterized by the monomer conversion rate of at least (0.95-1.0) ^χ X%, wherein X is a target conversion rate, i.e. preset conversion rate determined by the process conditions, for the selected polymerization process.

A dispersion medium for a layered silicate suspension, as well as a medium for polymerization and a medium for a rubber solution, is selected depending on technical requirements for the process of synthesis of polymers and for a final product.

The layered silicate suspension is prepared by dispersing silicate in a dispersion medium, for example in hydrocarbon solvents, under stirring for 10-90 minutes at temperature of between minus 90 to plus 100°C. It should be noted that the temperature mode for the preparation of a clay suspension depends on the temperature mode maintained during the polymerization of a modified polymer and on the properties of the suspension medium.

In one embodiment of the claimed invention, the modified rubbers comprise from 1.0 to 50 wt.% of layered silicates.

An increase in the amount of layered silicate higher than 50 wt.% is possible but inadvisable since that does not provide a further reduction in cold flow because at already 50 wt.% of layered silicate, the material loses its ability to flow in tests carried out according to GOST 19920.18-74 (cold flow is equal to 0 mm/h), but processability of the polymer or properties of the vulcanized rubbers based on rubbers comprising more than 50 wt.% of silicates can deteriorate.

In addition, at a dose of layered silicates in the modified rubber of more than 30 wt.%), strength and hysteresis characteristics of vulcanized rubbers based on such rubbers deteriorate.

The amount of layered silicates in the modified rubber of less than 1.0 wt.% does not reduce cold flow of rubber and not improve properties of vulcanized rubbers based thereon, regardless of the grade of layered silicate.

Physical modification of rubber is carried out by addition of from 5 to 50 wt.% of a layered silicate suspension prepared by dispersing the silicate in a hydrocarbon solvent under stirring for 10-90 minutes at temperature of between minus 90 to plus 100°C to a polymerizate at a monomer conversion rate of less than (0.95-1.0) ^χ X(%) (wherein X is a target conversion rate, i.e. preset conversion rate determined by the process conditions, for the selected process of polymerization). Thus, in the synthesis of 1,4-cis-butadiene rubbers, X is (95-100)%, more preferably from 99 to 100%, whereas in solution polymerization of polyisobutylene and butyl rubbers, X is (5- 100)%, more preferably from 10 to 80%, and more preferably from 20 to 40, prior to or after stopping (breaking of polymerization) and addition of an antioxidant. As was noted above, a temperature mode for the preparation of a clay suspension depends on the temperature mode maintained during the polymerization of the modified polymer and on the properties of the hydrocarbon suspension medium. The most suitable temperature for the preparation of a layered silicate suspension used for modification of 1 ,4-polybutadiene rubber ranges from 15 to 100°C, and for the modification of polyisobutylene or butyl rubber, the most suitable temperature ranges from minus 90 to minus 15°C.

Wherein, aliphatic (pentane, isopentane, hexane, heptane, isooctane, n-octane, petroleum ether, hexane-heptane hydrocarbon fraction in various hexane/heptane ratios, etc.), alicyclic (cycloheptane, cyclohexane, methylcyclohexane, cycloheptane, etc.), aromatic hydrocarbons (benzene, toluene, xylene, ethylbenzene, diethybenzene, isobutylbenzene, etc.), inert halogenated Ci-C₄ hydrocarbons (chloromethane, chloromethylene, dichloromethane, chloroethane), and mixtures thereof of various compositions may be used as suitable solvents, depending on the selected polymerization method.

In another embodiment of the invention, the technical result is achieved by physical modification of rubbers by adding a layered silicate suspension prepared by dispersing the silicate in a part of the polymerizate or solution of rubber, wherein the part comprises from 5 to 180 wt.% of the layered silicate based on the polymer comprised in said part of the polymerizate or solution of rubber under stirring for from 10 to 90 minutes at temperature of from minus 90 to plus 100°C, to the polymerizate at a monomer conversion rate of (0.95-1.0) x X(%), wherein X is a target conversion rate, i.e. preset conversion rate determined by the process conditions, for the selected process of polymerization. In the synthesis of 1,4-cis-butadiene rubbers, X is (95- 100)%, more preferably from 99 to 100%), whereas in solution polymerization of polyisobutylene and butyl rubbers, X is (5-100)%, more preferably from 10 to 60%, and more preferably from 20 to 40, prior to or after the termination of polymerization and addition of an antioxidant.

After completing the process, antioxidants may be introduced into the polymerizate in an amount of 0.2 to 3.0 wt.% based on the weight of rubber antioxidants comprised in the polymerizate. Most effective and preferable loadings of antioxidants are 0.3 to 1.5 wt.% or 0.2 to 0.4 wt.%. Phenolic or amine compounds may be used as the antioxidants for rubbers, or any other antioxidants (also including mixed ones) suitable for stabilizing rubbers.

Examples of phenolic antioxidants are: 2,6-di-tert-butyl-4-methylphenol (ionol, Agidol 1, alkophen, antioxidant); 2,2-di-(4-methyl-6-½rt-butylphenol)methane (antioxidant 2246, Agidol 2, Bis-alkophen), 2-methyl-4,6- bis((octylsulphanyl)methyl)phenol (IRGANOX 1520L); pentaerythritol tetrakis(3- (3,5-di-/ert-butyl-4- hydroxyphenyl)propionate) (IRGANOX 1010); 3,5-bis(l,l- dimethyl-ethyl)-4-hydroxy-C7-C9-(branched alkyl) ester of benzenepropanoic acid (IRGANOX 1135); 2,6-di-ter/-butyl-4-(4,6-bis(octylthio)-l,3,5-triazin-2- ylamino)phenol (BNX™ 565, Mayzo. Inc); octadecyl-3-(3,5-di-tert-butyl-4- hydroxyphenyl)propionate (IRGANOX 1076). Examples of amine antioxidants are: N- isopropyl-N'-phenyl-p-phenylenediamine (IPPD, VULCANOX 4010), N-(l ,3- dimethyl-butyl)-N'-phenyl-p-phenylenediamine (Antioxidant 4020, 6PPD), N(l ,3- dimethyl-phenyl)-N'-phenyl-p-phenylenediamine (7PPD), N-2-ethylhexyl-N'-phenyl- p-phenylenediamine (Novantox 8 PPDA, antioxidant C789), N,N'-diphenyl-p- phenylenediamine (DPPD), mixed antioxidants of Santo flex™ 134PD kind, which are a mixture of 6PPD and 7PPD products in a ratio of 1 to 2.

Rubber modified with layered silicate is isolated from the polymerizate or solution by methods of water-steam or anhydrous degassing known to a person skilled in the art. The method of isolation corresponds to the selected process for producing rubber.

Produced modified rubbers comprise from 1.0 to 50.0 wt.% of layered silicate and can be used in rubber mixtures useful in the manufacture of MRGs and tires, in particular, a tire sidewall, innerliners, automobile inner tube, tire tread.

Rubber mixtures according to the present invention, which comprise layered silicates (clays), differ from the known compositions of a similar intended purpose in that the rubber produced by the above-disclosed method of modification with layered silicate is comprised in the rubber mixture in an amount of from 5 to 130 phr on rubber or the sum of all rubbers constituting the mixture. MRG The amount of layered silicate-modified rubbers in vulcanized rubbers of less than 5 wp does not provide a sufficient amount of layered silicates in the vulcanized rubber, and, as a consequence, a required improvement of the properties of the vulcanized rubber (for example, gas impermeability, hysteresis properties, etc.) is not achieved. The amount of higher than 130 wp leads to an increased amount of layered silicate in vulcanized rubber, which has an adverse effect on the processability, elasticity, fatigue strength , strength, and other physicomechanical properties of vulcanized rubbers caused by significant reduction of the polymer fraction in a composite.

Rubber mixtures or elastomer compositions according to the present invention, in addition to modified rubbers produced according to the present invention, may further include other rubbers and various fillers, including clay, and other necessary ingredients known in the art. The composition of a rubber mixture is determined by its intended purpose and is known to a person skilled in the art. In one preferable embodiment of the invention, an elastomer composition may comprise a number of rubbers or mixtures thereof.

The amount of clay in the rubber mixture (Y), which was introduced therein as a component of a modified rubber, calculated based on the total elastomer part and expressed in phr, may range from preferably 1.0 to 40; more preferably from 2.5 to 20, and most preferably from 3 to 10 phr.

According to the invention, rubber mixtures can be produced on the basis of: a) rubber mixtures of preferably two or three rubbers selected from the group of butadiene (A), isoprene (natural or synthetic) (B), and/or butadiene-styrene (C), and/or styrene-butadiene-isoprene, and/or butyl rubbers (D), and/or other rubbers. Thus mixtures can be used for the manufacture of vulcanized rubbers of a required intended purpose, in particular, for a tire sidewall or tread, automobile inner tube, tire innerliner, diaphragm for a bladder press. In addition, one or more rubbers of group (A) and/or (B), and/or (C), and/or (D), and/or other rubbers (N) relating to any of said groups and synthesized in a hydrocarbon solvent may comprise layered silicates in an amount from 1 to 50 wt.%. The rubbers of group (A) or (D), in turns, can be modified by the method according to the present invention. In this case the total amount of rubbers in vulcanized rubber (phr) is calculated by the equation:

(A + Y_a) and/or (B+Y_b), and/or (C+Y_c), and/or (D+Y_d) and/or, (N) = 100 + Y; where

A, B, C, D, etc. are the amount of each rubber (phr) contained in a rubber mixture individually or as rubber modified with layered silicate;

Y = Y_a + Y_b + Y_c + Y_d is the total amount of clay (phr) contained in a rubber mixture as a component of one or more rubbers modified with layered silicate: (A +

Y_a), (B+ Y_b), (C+ Y_c) or (D + Y_d), and other rubbers (N);

b) mixtures of butyl rubbers (D) or polyisobutylene rubbers (E) modified by layered silicates by the method according to the present invention, with butyl rubbers (Dl) or polyisobutylene rubbers (El) non-modified by the method according to the present invention. In this case, the total amount of rubbers in vulcanized rubber (phr) is calculated by the equation:

((D + Y_d) and/or (E+Y_e)) + (Dl and/or El) = 100 + Y;

wherein

D, E, Dl, and El are the amount of each rubber (phr) contained in a rubber mixture individually or as a composite with layered silicate;

Y = Y_d and/or Y_e is the amount of clay (phr) contained in a rubber mixture as a component of one or more composites: (D+Y_d) and/or (E+Y_e).

c) one of rubbers modified with layered silicate by the method according to the present invention: butadiene rubber (A), butyl rubber (D), and polyisobutylene rubber (E) used for the production of vulcanized rubbers of a required intended purpose. In this case, the amount of rubber modified with layered silicate in vulcanized rubber is calculated by the equation:

(A or D or X) + Y = 100 + Y;

wherein

Y = Y_a or Y_d, or Y_e is the amount of clay (phr) contained in a rubber mixture as a component of modified rubber: (A+Y_a) or (D+Y_d) or (E+Y_e).

d) rubbers and elastomer composites, as disclosed in a), b), and c), but comprising one or more rubbers, or oil-filled composites with layered silicate.

The total amount of an elastomer composite consisting of clay-modified rubber in a rubber mixture can vary, according to the present invention, between 5 to (100+X) phr. A dose of less than 5 phr does not provide the amount of clay in vulcanized rubber, which ensures a desired effect. A dose of (100+X) phr is the maximum possible amount of a polymer material in vulcanized rubber in terms of the principles for calculating the composition of the vulcanized rubber.

The addition of a composite(s) prepared according to the present invention to a rubber mixture allows a reduction in the amount therein of fillers added according to the selected composition at the step of mixing the rubber mixture, such as precipitated colloidal silica, pyrogenic silica, black carbon, and other fillers (for example, such as kaolin, calcium carbonate, bentonite, layered silicate), for partial and complete compensation of the amount of layered silicate added to the mixture.

Rubber mixtures according to the invention can include the following ingredients:

a) fillers: silica (colloidal silicic acid), black carbon, kaolin, calcium carbonate, bentonite, layered silicate;

b) silanizing agents, in case of using finely-dispersed precipitated colloidal silica as a filler (a);

c) a vulcanizing system of agents: sulfur or sulfur donors, vulcanization accelerators such as sulfenamides, thiurams, thiazoles, guanidines, etc., and combinations thereof, which are used to accelerate the process of rubber vulcanization and obtain the optimal structure of a vulcanization network; vulcanization activators, such as metal oxides, amines, etc., among which zinc oxide is commonly used; and vulcanized agents such as alkylphenol-formaldehyde resins, alkylphenolamine resins or peroxides for vulcanization of rubbers based on butyl rubbers, halobutyl rubbers, and polyisobutylene rubbers;

d) processing additives improving dispersing of fillers and processability of rubber mixtures;

e) plastisizers and softeners, in particular selected from the group including: petrochemical products, plant oils, synthetic ether resins, derivative products of the coal-mining industry, synthetic oligomer functionalized and non-functionalized resins; f) anti-aging agents/antiozonants/antifatigue agents of physical and chemical action;

g) other agents providing the achievement of a required complex of processing, vulcanizing, physicomechanical, and performance characteristics, including, for example, modifiers; fillers, including fibrous, laminated, polymer (such as cross-linked polymer gels); agents preventing reversion during vulcanization and increasing heat resistance of vulcanized rubbers; improving tackiness and other properties.

Rubber mixtures according to the present invention can be prepared by using linear, branched or chemically modified butadiene, isoprene, butadiene-styrene, butadiene-styrene-isoprene rubbers, butyl rubbers and other rubbers, which are produced by both solution polymerization (solution rubbers) and emulsion polymerization (emulsion rubbers).

Rubber mixtures can be prepared, according to the present invention, by using natural rubber of various manufactures, tradenames and grades: from RSS (Rid Smoked Shits) to IRQPC (International Standards of Quality and Packing of Natural Rubber).

A rubber mixture can also comprise oil-filled grades of rubbers, for example, such as emulsion and solution butadiene-styrene or butadiene rubbers whose production methods are disclosed, for example, in US7915349, US6800689, and US6602942 (fully incorporated herein by reference). The reinforcing fillers, according to the present invention, which can be used in rubber mixtures for tire sidewalls, treads, innerliner, automobile inner tube, vulcanized rubber as base fillers, are black carbon, synthetic amorphous silica, preferably precipitated silica used both individually or in combination with black carbon.

Black carbon used according to the present invention can be, for example, black carbon of grades N 121, N 220, N 330, N 339, N 550, N 683, N 772, N 990 or other grades, used both individually or in a combination, depending on the intended purpose of vulcanized rubber and its composition.

It is also possible to use diphase fillers, which are silica filler with black carbon applied on its surface; and diphase fillers whose surface is impregnated with a coupling agent or is chemically modified. Silica prepared by a pyrogenic method also can be used, for example, products known under tradename AEROSIL^® (Evonic Industries AG).

The silica filler (SF) is mainly selected from known grades having a specific area ranging between 40 and 600 m²/g, as measured by the BET method or CTAB method, and dibutyl phthalate (DBP) oil adsorption of between 50-400 cm³/100 g. In a preferable embodiment, silica has a BET surface area of from 100 to 250 m7g, a CTAB surface area of 100 to 250 m²/g, and oil absorption (DBP) of between 150 and 250 cmVl OO g (measured according to GOST 25699.2-90; EP-A-157.703). A suitable precipitated silica filler can be selected from the products of grades BC-50, BC-100, BC-120 (JSC "Soda", Russia), Zeosil 1165 MP (Rhone-Poulenc SA); Ultrasil VN2, Ultrasil VN3, Ultrasil 7000 GR; and AEROSIL^® (Evonik Industries AG); Hi-Sil 210, Hi-Sil 190, Hi-Sil 215, Hi-Sil 233, Hi-Sil 255 (PPG Industries Inc.); KS 404, KS 300, and Perkasil 233 (Akzo Nobel); Zeopol 8745, Zeopol 8755 (Huber); Rosil-175 (JSC "Soda", Russia), etc.

The amount of silica in an elastomer composition may be from 3 to 100 phr, preferably from 5 to 80 phr, and more preferably from 10 to 95 phr. If the amount of silica is less than 3 phr, this amount can be insufficient to obtain required properties of vulcanized rubber (adhesion, strength, hysteresis characteristics, etc.). On the other hand, when it exceeds 100 phr, the processability and tensile mechanical properties deteriorate.

Rubber mixtures comprising silica- filled elastomers comprise silanizing agents

(coupling agents of silica with elastomers). Most frequently used coupling agents are bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3- trimethoxypropyl)tetrasulfide, bis(2-trimethoxysilylethyl)terasulfide, 3- mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2- mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3- nitropropyltrimethoxysilane, 3 -nitropropyltriethoxysilane, 3- chloropropyltrimethoxysilane, 3 -chloropropyltriethoxysilane, 2- chloroethyltriethoxysilane, 3 -trimethoxysilylpropyl-N, N- dimethylthiocarbamoyltetrasulfide, 3 -trimethoxysilylpropylbenzothiazol tetrasulfide, 3-triethoxysilylpropylmethacrylate monosulfide, etc. Among the above-indicated components, bis(3-triethoxysilylpropyl)tetrasulfide and 3- trimethoxysilylpropylbenzothiazol tetrasulfide are most preferable. In addition, coupling agents can be used that are compositions of the above-recited compounds and the above-recited coupling agents applied on a powder carrier, for example, black carbon.

It is possible to use other coupling agents intended to improve compatibility between SF and rubber, for example, such as NXT and NXT Z 100 (Momentive). SF-filled rubber mixtures, as a rule, also comprise processing additives which improve dispersing of fillers and processability of rubber mixtures. Examples of such additives may be fatty acid derivatives (zinc salts and ethers, and mixtures thereof) known under tradenames Struktol E44, Struktol GTI, Actiplast ST, which improve dispersing of fillers and reduce the viscosity of the mixture.

Rubbers are vulcanized by using vulcanizing agents known in the prior art, for example, elemental sulfur, sulfur donors, for example, N,N'-dimorpholyldisulfide, polymer polysulfides, etc. Elemental sulfur or polymer sulfur is most commonly used in the tire industry. As known in the art, a dose of vulcanizing agents in vulcanized rubber is, as a rule, between 0.5 to 4.0 phr, sometimes can reach 10 phr. Sulfur is usually used together with such ingredients as vulcanization activators, in particular, oxides and hydroxides of alkaline-earth metals (Zn, Mg, Pb, Ca) in combination with fatty acids; accelerators, in particular, sulfenamides, thiazoles, thiurams, guanidines, urine derivatives, etc.; and vulcanization retarders, in particular, phthalic anhydride, N- nitrosodiphenylamine, and cyclohexylthiophthalimide. Their amounts depend on the amount of a vulcanizing agent and requirements for vulcanization kinetics and the structure of a vulcanization network.

A typical vulcanizing system for cross-linking vulcanized rubbers based on butyl rubbers or halobutyl rubbers, or polyisobutylene rubbers may be based on peroxide and comprises a peroxide vulcanizing agent, for example, dicumyl peroxide, di-ter/-butylperoxide, benzoylperoxide, 2,2'-bis( rt-butylperoxy)-diisopropylbenzene (VulcupR 40KE), benzoylperoxide, 2,5-dimethyl-2,5-di(½/-t-butylperoxy)-hexine-3, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 2,5-bis(tert-butylperoxy)-2,5- dimethylhexane and the like. A preferred peroxide vulcanizing agent comprising dicumyl peroxide is available under tradename DiCup-40C. A peroxide vulcanizing agent is correspondingly used in an amount of from about 0.2 to about 7 phr, preferably from about 1 to about 6 phr, most preferably about 4 phr. Peroxide vulcanizing co-agents are also useful. In that respect, the following agents can be mentioned: triallylisocyanurate (TAIC) available under tradename DIAK (DuPont company) or N,N'-w-phenylenedimaleimide known as HVA-2 (DuPontDow), triallyl cyanurate (TAC), or liquid polybutadiene known as Ricon D 153 (available from Ricon Resins company). The amounts of these agents may be equivalent to or less than the amounts of peroxide vulcanizing agents.

A vulcanizing system of agents for rubbers of automobile inner tubes, innerliners, bladder press diaphragms , based on butyl rubbers, halobutyl rubbers, and mixtures thereof with isoprene and/or butadyene rubbers can comprise phenol formaldehyde resins (for example, sulfur-containing alkylphenol formaldehyde resin, Octophor 105) or alkylphenolamineresins (for example, Octophor N), and other resins used in the art as vulcanizing agents.

As plastisizers and softeners, in the present invention there are useful petrochemical products, plant oils (for example, rape oil), synthetic ether oils, derivative products of the coal-mining industry, synthetic oligomeric functionalized and non-functionalized products (see [Rubber Technologist's Handbook, Volume 2, Capert: Rubber Additives - Plasticisers and softeners / J.R. White, S.K. De, 2001 ; pp. 198-200] fully incorporated herein by reference).

The composition of vulcanized rubbers for tires and MRGs, as a rule, include ingredients of the following intended purpose: anti-aging agents, antiozonants, antifatigue agents and other components providing a required complex of processing, vulcanizing, physicomechanical, and performance characteristics, for example, modifiers; fillers, including fibrous, laminated, polymer (such as cross-linked polymer gels), etc.; agents preventing reversion during vulcanization and increasing heat resistance of vulcanized rubbers; improving tackiness and other agents. The nature of such compounds and their amounts in vulcanized rubber depend on the required properties of rubber mixtures and vulcanizates and are well known to a person skilled in the art (see, for example, A.M. Pichugin, Materialovedcheskie aspecty sozdaniya shinnykh resin [Materials science aspects of tire rubber development]; F.F. Koshelev, A.E. Kornev, A.M. Bukanov, Obschaya tekhnologiya resiny [General technology of rubber]; P.I. Zakharchenko, F.I. Yashunskaya, V.F. Evstratov, P.N. Orlovskii (Editorial team). Spravochnik rezinshchika. Materialy rezinovogo proizvodstva. [Handbook of Rubber Manufacturer: Materials for Rubber Production]; https:/ books.***.ru/books?id=2rxFOm68Ui8C&pg=PA431&lpg=PA431&dq=rubb er+technologisfs+handbook&source= i&ots=zN g2JXB3n&sig=r2ewGaHVFZQoKC

6GCakUnedOs&hl=ru&sa=X&ved=0CEcO6AEwBmoVChMIqpT0s9ixyAIVYrlvChl zoQ6 #v=onepage&q-rubber%20technologist^,s%20handbook&f=false) (both of which documents are fully incorporated herein by reference).

Mixtures are prepared by methods known in the art and disclosed, for example, in [Jon S. Dick, Rubber Technology. Compounding and Testing for Performance. Carpet: Mixing] (fully incorporated herein by reference), preferably by using closed rubber mixers, for example, Banbury or Intermix types. The process of mixing can be carried out in two or three steps, wherein the second and the third steps are intended to add components of the vulcanizing group to the mixture.

Rubber mixtures thereby prepared are characterized by improved processing properties, and vulcanized mixtures have increased fatigue strength and are characterized by lower hysteresis losses.

Examples

The invention is supported by the following examples of the production of butadiene rubber SKD-ND or butyl rubber, which are modified with bentonite "Bentonit" (Barnaul, Russia) and/or organoclay Dellite^®72T produced by Laviosa Chimica Mineraria S.p.A. (Italy).

The cold flow of rubbers modified according to the present invention was measured according to GOST 19920.18-74. The results of the evaluation of the cold flow of rubbers are given in Tables 1 and 2. In particular, an effect of a dose of organoclay Dellite^®72T on the cold flow of SKD-ND for examples 1 and 4-17 is shown in Table 1. An effect of clay "Bentonit" on the cold flow of SKD-ND for examples 1 and 18-31 is shown in Table 2.

The effect of butadiene rubbers (SKD-ND or BR- 1243 Nd B) modified according to the invention on the properties of vulcanized rubbers was studied by using model rubber compounds for sidewalls (the formulation is given in Table 3) and rubber compounds for tire treads (the formulation is given in Table 4) compared to vulcanized rubbers comprising non-modified SKD-ND.

As a base for modification with layered silicates and as a component of rubber mixtures, SKD-ND rubber was used, which is butadiene rubber and a product of polymerization of butadiene in a solution in the presence of rare earth metal catalysts, wherein said rubber comprised at least 96% of 1 ,4-cis-monomers available (Sibur, Ru).

Rubbers mixtures also comprised: synthetic butadiene-styrene rubber SSBR- 2560 comprising 62-70% of 1,2-units, which is a polymerization product of butadiene- 1 ,3 with styrene in a hydrocarbon solvent in the presence of anionic initiators (Sibur, Russia); and natural rubber RSS-1 (SSP.RUBBER (THAILAND) CO., LTD.).

Rubber mixtures further comprised the following ingredients: black carbon N339 (Yaroslavskii zavod tekhnicheskogo ugleroda [Yaroslav Technical-Grade Carbon Plant]); precipitated colloidal silica Zeosil 1165 MP (Solvay), silanizing agent Si-69 (Evonic), anti-aging agent 6PPD (Esatman Santoflex), anti-aging agent TMQ (Chemtura), protective waxes Antilux 11 1 and Antilux 654 (RheinChemie), zinc oxide (Ltd. "Empils", Ru), stearic acid (JSC "Nefis Cosmetics", Ru), processing additive Actiplast ST (RheinChemie), diphenylguanidine (DFG, RheinChemie), sulfur, industrial grade 9998 (NK Lukoil, Ru), plastisizer Norman 346 (JSC Orgkhim", Ru), and accelerator TBBS (Vulkacit NZ, Lanxess).

Rubber mixtures were prepared in plasticorder Plastograph EC Plus, Model 2008 ("Brabender", Germany). The free volume of the mixing chamber with bump rotors N50 EHT was 80 cm . A load factor was 0.7. The rubber mixtures provided in Table 3 were prepared in two steps:

step 1 comprised mixing all ingredients, except a vulcanized group (i.e. sulfur, TBBS), at the initial temperature of the chamber walls of 60°C; the maximum temperature in the chamber during the mixing process was not higher than 130°C, and the rotor speed was 40 rpm; and

step 2 comprised adding the vulcanizing group (sulfur, TBBS) to the rubber mixture at the initial temperature of the chamber walls of 70°C; the maximum temperature in the chamber during the mixing process was not higher than 130°C, and the rotor speed was from 40 to 50 rpm.

The rubber mixtures provided in Table 6 were prepared in three steps:

step 1 comprised mixing all ingredients, except a vulcanized group (i.e. sulfur, DFG, TBBS), at the initial temperature of the chamber walls of 90°C; the maximum temperature in the chamber during the mixing process was not higher than 155°C, and the rotor speed was 40 rpm;

step 2 comprised dispersing-mixing of the mixture of step 1 without adding additional ingredients at the initial temperature of the chamber walls of 120°C; the maximum temperature was not higher than 155°C, and the rotor speed was 60 rpm; and step 3 comprised adding the vulcanizing group to the rubber mixture at the initial temperature of the chamber walls of 65°C; the maximum temperature was not higher than 110°C, and the rotor speed was 40 rpm.

Rubbers prepared according to Table 3 were vulcanized at 155°C for 20 minutes. Rubbers prepared according to Table 6 were vulcanized at 160°C for 20 minutes.

The fatigue strengthof the vulcanized rubbers provided in Table 3 was evaluated measured to GOST 261 -79 (amplitude 100%, 250 cycle/min). The test results are given in Table 4.

Hysteresis characteristics of the vulcanized rubbers (mechanical loss tangent, tg5 at 60°C) prepared according to Examples 1 , 7, and 21 (Table 3) and Examples 33 and 34 (Table 6) were determined by means of an RPA 2000 ("Alpha Technologies") by ASTM D 6601 -02 Standard Test Method at an amplitude of 10%) and a frequency of 10 Hz. The test results are given in Tables 5 and 7, respectively. The parameter "tg5" at 60°C characterizes both the total level of hysteresis losses in vulcanized rubber under dynamic operating conditions and the value of rolling losses in vulcanized tread rubbers.

The molecular weight characteristics of rubbers (Mn, Mw, Mw/Mn) were determined by gel-permeating chromatography in a device Agilent 1200f "Agilent Technologies"; the content of 1 ,4-cis-monomers was measured by using an IR- spectrometer Excalibur 3600 "Varian" with a multiple attenuated total reflectance (ATR) accessory; Mooney viscosity was measured according by ASTM D 1646; and characteristic viscosity was determined by using an Ubbelohde viscometer (5.43% solutions in toluene).

Example 1. (comparative)

Butadiene rubber SKD-ND was prepared in a hydrocarbon solvent in the presence of a Neodymium-containing organometallic complex catalyst according to the method disclosed in patent US 5017539 (Example 3). The concentration of butadiene in the reaction mass was 10 wt.%. A dry residue of the reaction mass in the last reactor was 9.68 wt.%. The conversion rate of butadiene- 1 ,3 immediately prior to modification was 97 wt.%.

The obtained rubber SKD-ND had the following characteristics: - the content of 1,4-cis-monomers, 97 wt.%;

- molecular weight Mn was 132* 10 g/mol, Mw was 517* 10 g/mol;

- polydispersity (Mw/Mn)was 3.92;

- characteristic viscosity, 3.55 dl/g;

- Mooney viscosity, ML( l +4) at 100°C was 43 units;

- cold flow, 30 mm/h.

Example 2

A suspension of organoclay Dellite^®72T in hydrocarbon solvent Nefras was prepared in a separate apparatus or a chamberless mixer prior to be added to a polymerizate, at temperature of 60°C and under continuous dispersion of the prepared solution for 25 minutes to reach a homogenous consistency. The concentration of the suspension of Dellite^®72T in the hydrocarbon solvent was 10 wt.%. The obtained suspension was designated as Suspension 1.

Example 3

A suspension of organoclay Dellite^®72T in a hydrocarbon solvent Nefras was prepared in a separate apparatus or a chamberless mixer prior to be added to a polymerizate at temperature of 60°C and under continuous dispersion of the prepared solution for 25 minutes to reach a homogenous consistency. The concentration of the suspension of Dellite^®72T in Nefras was 25 wt.%. The obtained suspension was designated as Suspension 2.

Example 4

A modified rubber was produced according to Example 1 with a difference consisting in that a 10% Suspension 1 of Dellite^®72T prepared according to Example 2 was added to a polymerizate with a 9.7% dry residue at a monomer conversion rate of 97 wt.%. The content of Dellite^®72T in the obtained product was 1 wt.% based on rubber.

The modifier suspension was supplied under continuous stirring at temperature of 60°C (±5). The time of modification was 60 minutes. Then the obtained rubber was stopped with softened alkalized water, and after addition of antioxidant was delivered to the step of degassing and drying.

Example 5

A modified rubber was obtained in the same way as disclosed in Example 4 with a difference consisting in that the modifier suspension was Suspension 2 according to Example 3.

The cold flow of the rubbers prepared according to examples 4 and 5 was reduced on average by 20%, i.e. from 30 to 23.9 mm/h (see Table 1).

to

o O

Table 1. An effect of the dose of organoclay Dellite"72T on the cold flow of SKD-ND

Example 6

A modified rubber was produced according to Example 1 with a difference consisting in that a 10% Suspension of Dellite^®72T prepared according to Example 2 (Suspension 1) was added to a polymerizate with a 9.7% dry residue at a monomer conversion rate of 97 wt.% in an amount of 6 wt.% of Dellite*72T based on rubber. The modifier suspension was supplied under continuous stirring and at temperature of 60°C (±5°C). The time of the modification process was 60 minutes.

The obtained rubber was stopped with softened alkalized water and after addition of an antioxidant was delivered to the step of degassing and drying.

Example 7

A modified rubber was obtained in the same way as disclosed in Example 6 with a difference consisting in that the modifier suspension is Suspension 2 according to Example 3.

The cold flow of the rubbers prepared according to examples 6 and 7 was reduced on average by 54%, i.e. from 30 to 13.9 mm/h (see Table 1 ).

Example 8

A modified rubber was produced according to Example 1 with a difference consisting in that a 10% Suspension of Dellite^¾'72T prepared according to Example 2 was added to a polymerizate at a monomer conversion rate of 97 wt.% in an amount of

it)

10 wt.% Dellite 72T based on rubber. The modifier suspension was supplied under continuous stirring and at temperature of 60°C (±5°C). The time of the modification process was 60 minutes. The obtained rubber was stopped with softened alkalized water and after addition of an antioxidant was delivered to the step of degassing and drying.

Example 9

A modified rubber was obtained in the same way as disclosed in Example 8 with a difference consisting in that the modifier suspension is Suspension 2.

The cold flow of the elastomer composites prepared according to examples 8 and 9 was reduced on average by 71 %o, i.e. from 30 to 8.6 mm/h (see Table 1 ).

Example 10

A modified rubber was produced according to Example 1 with a difference consisting in that a 10% Suspension of Dellite^&20T prepared according to Example 2 (Suspension 1) was added to a polymerizate at a monomer conversion rate of 97 wt.% in an amount of 20 wt.% of Dellite^®20T based on rubber. The modifier suspension was supplied under continuous stirring and at temperature of 60°C (±5°C). The time of modification was 60 minutes. The obtained rubber was stopped with softened alkalized water and after addition of an antioxidant was delivered to the step of degassing and drying.

Example 11

A modified rubber was obtained in the same way as disclosed in Example 10 with a difference consisting in that the modifier suspension was Suspension 2 according to Example 3.

The cold flow of the modified rubbers obtained according to examples 10 and 11 was reduced on average by 81.0%, i.e. from 30 to 5.7 mm/h (see Table 1 ).

Example 12

A modified rubber was produced according to Example 1 with a difference consisting in that a 10% Suspension of Dellite^®72T prepared according to Example 2 was added to a polymerizate at a monomer conversion rate 97 wt.% in an amount of 30 wt.%) of Dellite^®72T based on rubber. The modifier suspension was supplied under continuous stirring and at temperature of 60°C (±5°C). The time of modification was 60 minutes. The obtained rubber was stopped with softened alkalized water and after addition of an antioxidant was delivered to the step of degassing and drying.

Example 13

A modified rubber was obtained in the same way as disclosed in Example 12 with a difference consisting in that the modifier suspension was Suspension 2 according to Example 3.

The cold flow of the modified rubbers obtained according to examples 12 and

13 was reduced on average by 98.0%, i.e. from 30 to 0.6 mm/h (see Table 1).

Example 14

A modified rubber was produced according to Example 1 with a difference consisting in that a 10% Suspension of Dellite^®72T prepared according to Example 2 was added to a polymerizate at a monomer conversion rate of 97 wt.% in an amount of 40 wt.%) of Dellite^®72T based on rubber. The modifier suspension was supplied under continuous stirring and at temperature of 60°C (±5°C). The time of modification was 60 minutes. The obtained rubber was stopped with softened alkalized water and after addition of an antioxidant was delivered to the step of degassing and drying.

Example 15

A modified rubber was obtained in the same way as disclosed in Example 14 with a difference consisting in that the modifier suspension was Suspension 2 according to Example 3.

The cold flow of the modified rubbers obtained according to examples 14 and 15 was reduced on average by 99.0%, i.e. from 30 to 0.3 mra/h (see Table 1).

Example 16.

A modified rubber was produced according to Example 1 with a difference consisting in that a 10% Suspension of Dellite®72T prepared according to Example 2 was added to a polymerizate at a monomer conversion rate of 97 wt.% in an amount of 50 wt.% of Dellite®72T based on rubber. The modifier suspension was supplied under continuous stirring and at temperature of 60°C (±5°C). The time of modification was 60 minutes. The obtained rubber was stopped with softened alkalized water and after addition of an antioxidant was delivered to the step of degassing and drying.

Example 1 7.

The cold flow of the modified rubbers obtained according to examples 16 and 17 was reduced by 100%, i.e. from 30 to 0 ram/h (see Table 1)

Examples [18-31 ]

Modification of rubber was performed in the same way as disclosed in Examples 4- 17 with a difference consisting in that organoclay Dellite®72T used as the modifier was replaced with a suspension of non-modified clay "Bentonit". The suspension of non-modified clay "Bentonit" was prepared similarly to the suspension of organoclay Dellite®72T, as disclosed in Examples 2 and 3, respectively. The resultant product was isolated by non-aqueous degassing of the solvent.

The obtained rubbers according to examples 1 8-31 were stopped with softened alkalized water and after addition of an antioxidant was delivered to the step of degassing and drying. An effect of the dose of "Bentonit" on the cold flow of the modified rubbers prepared under the conditions of Examples 18-31 is given in Table 2.

<-_Λ © O

Table 2. An effect of the dose of "Bentonit" on the cold flow of SLD-ND

Parameter Example 1 Example Example Example Example Example

(sample) 18/19 20/21 22/23 24/25 26/27

Cold flow, mm/h 30.0 29.9/29.3 27.2/28.0 22.1/22.7 18.5/18.0 12.0/12.6

(relative change to (100) (-1.5) (-8.0) (-25) (-39) (-59)

Example 1 , %)

A dependence of the cold flow of rubber SKD-ND on the content and type of layered silicate is shown on Fig. l . It is evident from the obtained dependence that the cold flow of rubber decreases with increasing the content of any of the tested layered silicates in the rubber. In the comparison of the effects of two grades of layered silicates on the cold flow of SKD-ND, namely, of Bentonit and Dellite^®72, it has been found that the use of organo-modified Dellite^®72 leads to the most significant reduction in cold flow.

The rubbers prepared according to examples 1 and 1 ; 4-9; 16-17; 18-23; and 30-31 were tested as a components of a model rubber mixture for tire sidewalls (see Table 3). As can be seen from Table 4, the rubbers comprising Bentonit in an amount of 6-50 wt.% and Dellite^® 172 in an amount of 5 wt.% significantly improve fatigue strength of said vulcanized rubbers. Hysteresis losses (see Table 5) in the provided vulcanized rubbers are also apparently decreased if they comprise rubbers modified with layered silicates.

o o

Table 3. Compositions of rubber mixtures for tire sidewalls, comprising rubbers prepared according to Examples 1 ; 4-9; 16-17; 18-

23; and 30-31

to o o

Table 5. Mechanical loss tangent (tg5)

Example 32 (reference sample)

Butadiene rubber (SKD-ND or BR- 1243 Nd B) was prepared in a hydrocarbon solvent in the presence of an Neodymium-containing organometallic complex catalyst at a concentration of butadiene in the reaction mass of 10 wt.%, according to Example 1 , with a difference consisting in that the dry residue of the reaction mass in the last reactor was 8.98 wt.%. The conversion rate of butadiene- 1,3 was 90 wt.%.

The rubber SKD-ND had the following characteristics:

— the content of 1,4-cis-units, 96 wt.%;

— molecular weight Mn was 148* 10^J g/mol, Mw was 465* 10^J g/mol;

— polydispersity (Mw/Mn) was 3.14;

— characteristic viscosity 3.05 dl/g;

— Mooney viscosity ML(l +4) at 100°C, 41 units; and

— cold flow, 25 mm/It.

Example 33

Modified rubber was prepared according to Example 32 with a difference consisting in that a 10% suspension of Dellite^®72T prepared according to Example 2 (Suspension 1) was added to a polymerizate at a monomer conversion rate of 90 wt.% in an amount of 15 wt.% of Dellite^®72T based on rubber. The modifier suspension was supplied under continuous stirring at temperature of 60°C (±5°C). The time of modification was 60 minutes.

Example 34

A modified rubber was obtained in the same way as disclosed in Example 33 with a difference consisting in that the modifier suspension was Suspension 2 according to Example 3. Compositions of the rubber mixtures containing SSBR-2560 (Sibur, Ru) and samples prepared according examples 32-34 are given in Table 6. A reference sample used for comparison of the characteristics was a rubber mixture of rubber SSBR-2560 and SKD-ND (Example 32).

Table 6. Compositions of model rubber mixtures for tire treads.

The results of hysteresis properties of the above-mentioned vulcanized rubbers given in Table 7 show that rubbers SKD-ND modified with layered silicate Dellite^®72T provide a reduction in rolling losses (tg8 at 60°C) by 17% relative to the reference sample (vulcanized rubber comprising non-modified SKD-ND). Table 7. Mechanical loss tangent (tg5)

Thus, it can be assumed that rubber SKD-ND modified with layered silicate is a composite, wherein a part of polymer chains penetrates the interlayer space of organoclays, and then said part of the polymer in the vulcanized rubber is maintained in occluded form. Such micro-volumes of rubber SKD-ND do not interact with the main reinforcing filler and form a phase with low hysteresis and improved fatigue characteristics, which can provide a reduction in hysteresis losses and an increase in the fatigue strength of the vulcanized rubber as whole.

Example 35. Preparation of a 15% suspension of organocla^'y Dellite^®72T in the mixture of isopentane (36 wt.%) and chloroethane (64 wt.%)

Isopentane and chloroethane were specially prepared according to the requirements to solvents used in the synthesis of butyl rubbers or polyisobutylene rubbers. The suspension was prepared directly prior to supplying it to a polymerizate at temperature of minus 45°C, either in a separate apparatus under continuous stirring for 25 minutes or in a chamberlass mixer.

Example 36 (comparative). Preparation of butyl rubber

Butyl rubber (BR) was prepared under the conditions disclosed in patent RU 2259376 (see p.4, Examples 1 and 4). A reactor was filled with batch to a 70% reactor volume, wherein the batch comprised (in wt.%) isobutylene (42.7), isoprene (1.3), chloroethane (35.0), isopentane (21.0), and an initiator being ethylaluminum sesquichloride (EASC) in isopentane (concentration of 8 g/1) with the total amount of protonated complexes of 45%, in an amount of 2.26 L of the initiator solution based on 1 ton of batch. The process ran at minus 45°C. The polymerization was terminated by methods known in the art, for example, by adding isopropyl alcohol. The obtained polymerizate had the dry residue content of 15% and the monomer conversion rate of 35%. The rubber was characterized by a Mooney viscosity of 50 units and cold flow of 20 mm/h.

Example 37. Preparation of butyl rubber modified with layered silicate Butyl rubber (BR) was prepared under the conditions disclosed in Example 36 with a difference consisting in that a suspension of organoclay Dellite^®72T prepared according to Example 35 was added to a polymerizate with the dry residue content of less than 13% and the monomer conversion rate of 33% (which consists 95% of a target conversion rate) in an amount of 5 wt.% of clay based on rubber. Further, the process continued until the target conversion rate reached 35%. The polymerization was stopped by the methods known in the art, for example, by adding isopropyl alcohol. The rubber thereby prepared was characterized by a Mooney viscosity of 45 units and cold flow of 10 mm/h.

As follows from the provided data (see Tables 1 and 2, Fig. l ) and Example 37, physical modification at the final step of the polymerization process of rubbers with layered silicates provides a controlled reduction of their cold flow.

In addition, the use of rubber SKD-ND physically modified with layered silicate provides a reduction in hysteresis losses and an increase in fatigue strength of vulcanized rubbers, in particular of vulcanized rubbers for tire sidewall, as demonstrated in Tables 3, 4, and 5.

It has been also revealed that rubber SKD-ND filled with layered silicate at the polymerization step has a positive effect on hysteresis characteristics of tread vulcanized rubbers (see Table 7).

A positive effect of layered silicates on gas impermeability of vulcanized rubbers based on butyl-, halobutyl-, or polyisobutylene rubbers does not require additional confirmation since said effect is well known from the art and is disclosed in details in literature.

The present description and examples are intended for purposes of explaining and illustrating the present invention and cannot be regarded as limiting the scope of the invention. True spirit and scope of the invention seeking for legal protection is defined by the following claims.

Claims

1. A method for preparing rubbers with a reduced cold flow, wherein the rubbers are selected from the group comprising polybutadiene rubber, butyl rubber, and polyisobutyiene rubber, the method comprising adding a suspension of layered silicate to a polymerizate formed during preparation of the rubber by polymerization , followed by stabilization, degassing, isolation and drying the resultant product, characterized in that the silicate is added to the polymerizate in the form of a suspension when a monomer conversion rate reaches at least (0.95-1.0)*X%, wherein X is a target conversion for said polymerization process.

2. The method of claim 1 , characterized in that the resultant rubber is 1 ,4-cis- butadiene rubber, and X is (95* 100)%, preferably 99-100%.

3. The method of claim 1 , characterized in that the resultant rubber is butyl rubber or polyisobutyiene rubber, and X is (5* 100)%, preferably 10-80%, more preferably 20-40%.

4. The method of claim 1 , characterized in that the polymerizate is prepared by co-polymerization of a monomer(-s) in a solution in the presence of a polymerization initiator.

5. The method of claim 1 , characterized in that the layered silicate is selected from the group consisting of montmorillonite clays, kaolinite clays, chlorite clays, hydrated mica group, and alternating-layer minerals.

6. The method of claim 1 , characterized in that a dispersion medium of the suspension of the layered silicate is an aliphatic, alicyclic, aromatic hydrocarbon, or chlorinated hydrocarbon and/or a mixture thereof, and/or a part of the resultant polymerizate.

7. The method of claim 1 , characterized in that the layered silicate is a modified layered silicate, and the dispersion medium of the suspension is an aliphatic, alicyclic, aromatic, or chlorinated hydrocarbon, and/or a mixture thereof, and/or a part of the resultant polymerizate.

8. The method of claim 6 or 7, characterized in that the aliphatic hydrocarbon is selected from the group comprising pentane, isopentane, hexane, heptane, octane, isooctane, and hexane-heptane hydrocarbon fraction with various hexane/heptane ratios; and/or the alicyclic hydrocarbon is selected from the group comprising cyclopentane, cyclohexane, methylcyclohexane, and cycloheptane; and/or the aromatic hydrocarbon is selected from the group comprising benzene, toluene, xylenes, ethylbenzene, diethylbenzene, isobutylbenzene, and isopropylbenzene; and/or the chorinated hydrocarbon is selected from the group comprising chloromethane, dichloromethane, chloroethane, and chloromethylene.

9. The method of claim 1 , characterized in that the suspension of the silicate is prepared by dispersing silicate in the dispersion medium at a temperature of from minus 90 to plus 100°C under vigorous stirring for a time of 10 to 90 minutes.

10. The method of claim 1 , characterized in that the layered silicate is added to the polymerizate in the form of suspension in a solvent in an amount of 1.0 to 50 wt.% based on the rubber containing in the polymerizate.

11. The method of claim 1, characterized in that the silicate is added to the polymerizate in the form of suspension in the polymerizate at the silicate concentration of 5 to 180 wt.% based on rubber comprised in the part of the polymerizate forming the dispersion medium of said silicate suspension.

12. The method of claim 1 , characterized in that the silicate is added to the polymerizate in the form of suspension in a solution of rubber at the silicate concentration of 5 to 180 wt.% based on rubber comprised in the rubber solution.

13. The method according to any one of claims 6 to 12. characterized in that an antioxidant is added to the suspension of silicate in the selected medium in an amount of 0.2 to 3.0 wt.% based on the weight of rubber comprised in the polymerizate, preferably 0.3 to 1.5 wt.%, more preferably 0.2 to 0.4 wt.%.

14. The method of claim 1, characterized in that the amount of silicate in the modified rubber is from 1 to 50 wt.% .

15. A modified rubber with a reduced cold flow, prepared by the method according to any one of claims 1 to 14.

16. A rubber mixture for the manufacture of an article, the mixture comprising one or more modified rubbers according to claim 15.

17. The rubber mixture of claim 16, wherein the article is a tire element selected from a tire sidewall, a tire tread, a tire innerliner, automobile inner tube the mixture comprising one or more modified rubbers prepared by the method according to any one of claims 1 to 14.

18. An article manufactured from a rubber mixture according to any one of claims 16 to 17.