KR20000022378A - Rubber composition based on carbon black with silica fixed on its surface and diene polymer functionalized or modified by silanol functional group - Google Patents

Abstract

PURPOSE: A rubber composition is provided to present increased electric conductivity, to give improved hysteretic and physical properties. CONSTITUTION: A vulcanizing rubber composition comprises carbon black having silica fixed on the surface as a major reinforcing filler, and a functionalized diene polymer containing a polysiloxane block, having a silanol end or a functional group on a chain end, and a modified diene polymer according to the chain by the silanol function. The polysiloxane block has the silanol end of a formula £-(SiR1R2O)x-H|. In the formula, R1 and R2 are the same or different, are alkyl groups of carbon water 1 to 8, and x is an integral number of 1 or to 1500 extent.

Description

Rubber composition based on carbon black having silica adhered to the surface and diene polymer functionalized or modified by silanol functional groups

The present invention provides improved hysteresis and physical properties in a vulcanized state and comprises a diene polymer functionalized or modified by silanol functional groups and carbon black having silica fixed on the surface as a reinforcing filler. In particular, it relates to rubber compositions for use in the production of tire treads.

Since the need to save fuel and protect the environment is a priority, various semi-finished products incorporated into tire tread compositions, such as underlayers, gums of various types of rubber, or metallic or textile reinforcements Mechanically, for use in forming rubber compositions that can be used for the production of heavy metals, side rubbers or tire treads, and for obtaining tires with improved properties, in particular rolling resistance. It is desirable to produce polymers with good properties and as low as possible hysteresis.

In order to achieve the above object, a number of solutions have been proposed, in particular the properties of diene polymers and copolymers by coupling agents, starring agents or functionalized agents in the final stages of polymerization. A solution consisting of reforming has been proposed. In essence, many of these solutions focused on using modified polymers using carbon black as reinforcing fillers for the purpose of obtaining good interactions between the modified polymers and carbon black are white fillers, in particular silica. Some properties of the above-described compositions have low values because of the use of and because the special properties of tires using these compositions have low values (e.g. low wear resistance), they have proved inadequate. As described in the examples in the prior art, US Pat. No. 4,677,165, which may be used as a reference, discloses a living polymer functionalized with a benzophenone derivative to obtain improved properties of a composition comprising carbon black. The reaction is described. For the same purpose, US Pat. No. 4,647,625 describes functionalization of polymers by reaction of living polymers with N-methyl-pyrrolidine. EP 0,590,491 and EP 0,593,049 describe elastomers comprising amine functionalities that allow for better interaction between the polymer and carbon black.

In addition, several solutions have been proposed for the use of silica as a reinforcing filler in compositions intended for tire tread production. As an example, EP 0,299,074 and EP 0,447,006 describe functionalized polymers comprising alkoxysilane functional groups. Such functionalized polymers are described in the prior art as effective in reducing hysteresis and improving wear resistance, but because of the nature of these polymers, they are not suitable for use in compositions intended for the production of tire treads.

Moreover, these polymer formulations suffer from the problem of developing macrostructures that severely destroy potentially important properties while removing the polymerization solvent. In addition, this development cannot be easily controlled.

In addition, coupling reactions are frequently observed during the above-described functionalization reactions, in order to minimize this, generally an excess of alkoxysilane is used and / or vigorous mixing is used.

This interest in silica containing compositions has recently been demonstrated by EP 0,501,227, which includes thermodynamic processes of copolymers of diene copolymers and vinylaromatic compounds and the processes described in EP 0,157,703. Sulfur vulcanized rubber compositions are described which are obtained by using the particular precipitated silica obtained. This composition, which shows a good compromise between some contradictory properties, allows for the manufacture of tire treads with treads filled with special silica.

However, in compositions based on silica, it is necessary to use a relatively large amount of linking agent in order for the composition to have good mechanical strength. These materials have very low electrical conductivity and the electrostatic charges accumulated under special circumstances are not always effectively grounded, especially US Pat. No. 5,518,005, European Patent Application No. 0,705,722, which describes the use of conductive rubber strips through a tire tread. Use in more complex methods of producing tires using the method described in EP 0,718,126, or EP 0,556,890, which deals with the addition of special conductive polymers to the rubber composition constituting the tire tread. Preferred below.

More recently, WO 96/37547 uses carbon black with silica adhered to the surface as a reinforcing filler, based on functionalized or non-functionalized diene polymers, and using silane coating agents and coupling agents. The rubber composition to be used is described. Such compositions are believed to have improved hysteresis over compositions comprising carbon black as a reinforcing filler. However, silane coatings and coupling agents must always be used in relatively large amounts.

Summary of the Invention

According to the present invention, diene polymers having silanol functional groups at the ends of the chain, or polysiloxane blocks comprising silanol ends, or diene polymers modified along the chain by silanol functional groups which do not develop macrostructure during functionalization. (A) improvement as compared to that of rubber based properties on vulcanized compositions comprising carbon black with silica adhering to the surface as reinforcing fillers, especially those based on unfunctionalized or functionalized diene polymers employed in carbon black. Imparted hysteresis and physical properties (where the improved properties are on the same level as those of polymers based on functionalized or unfunctionalized dienes containing silica as binder and reinforcing filler), An incredible method has been invented which results in a markedly increased electrical conductivity in comparison.

The present invention is characterized in that the diene polymer is a diene polymer having a silanol functional group at the end of the chain, or a polysiloxane block having silanol ends, or a diene polymer modified along the chain by silanol functional groups. And vulcanized rubber compositions comprising modified or modified diene polymers, carbon black having silica adhered to the surface as a reinforcing filler, and other conventional constituents of the composition.

Preferred suitable as polysiloxane blocks having silanol ends are those of the formula [-(SiR ₁ R ₂ O) _x -H], wherein R ₁ and R ₂ are the same or different and are alkyl groups of 1 to 8 carbon atoms, x Is an integer of 1 to 1500, preferably 1 to 50).

What is understood as a diene polymer suitable for use in the compositions of the present invention is any homopolymer obtained by the polymerization of conjugated diene monomers having 4 to 12 carbon atoms, copolymerized with one or more conjugated dienes or with one or more conjugated dienes. Any copolymer obtained by copolymerization with at least one vinylaromatic compound having 8 to 20 carbon atoms. Suitable as conjugated dienes are in particular butadiene-1,3,2-methyl-1,3-butadiene, 2,3-di (C ₁ -C ₅ -alkyl) -1,3-butadiene (eg 2,3- Dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene, 2-methyl-3-isopropyl-1,3-butadiene, Phenyl-1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene and the like).

Suitable vinylaromatic compounds are, in particular, styrene, ortho-, meta- and paramethylstyrene, commercially available mixtures "vinyltoluene", para-tert-butylstyrene, methoxystyrene, vinylmethylene, divinylbenzene, vinylnaphthalene And so on.

The copolymer may include 99% to 20% by weight of diene units and 1 to 80% by weight of vinylaromatic units.

The functionalized diene polymer has its silanol functionality at the end of the chain, or by silanol functionality which may have a polysiloxane block having silanol ends or any microstructure which is a function of the polymerization conditions used. It is modified along the chain. The polymer may be a block polymer, statistical polymer, sequenced polymer, microsequened polymer, and the like, and may be prepared in dispersion or solution. In the case of anionic polymerization, the microstructure of these polymers is determined by the presence or absence of a modifying agent and / or randomizing agent, and by the amount of the modifying and / or randomizing agent used.

Preference is given to polybutadiene, in particular polyisoprene and butadiene-styrene copolymers having a 1,2-unit content of 4% to 80%, in particular 4 to 50% by weight of styrene and more particularly 20 to 40% by weight. Butadiene-isoprene copolymer having a 1,2-bond content of 4% to 65% of the butadiene moiety and a trans-1,4-bond content of 30% to 80%, in particular an isoprene content of 5 to 90% by weight and free transition temperature (T _g) of the isoprene -40 ℃ to -80 ℃ - a styrene copolymer, especially a styrene content of 5 to 50% by weight to the T _g is -25 ℃ to -50 ℃. For butadiene-styrene-isoprene copolymers, suitable are 5 to 50% by weight, more particularly 10 to 40% by weight, 15 to 60% by weight of isoprene, more particularly 20 to 50% by weight, butadiene content 5 to 50% by weight, more particularly 20 to 40% by weight, the 1,2-unit content of the butadiene portion is 4% to 85% and the trans-1,4-unit content of the butadiene portion is 6% to 80% And the content of 1,2-units and 3,4-units of the isoprene portion is 5% to 70%, and the trans-1,4-unit content of the isoprene portion is 10% to 50%, more generally Butadiene-styrene-isoprene copolymers having a T _{g of} from -20 ° C to -70 ° C are suitable.

As for the polymerization initiator, known anionic or nonionic single or polyfunctional initiators can be used. However, preference is given to using initiators comprising alkali metals such as lithium or alkaline earth metals such as barium. Suitable as organolithium initiators are in particular those having at least one carbon-lithium bond. Representative compounds include aliphatic organolithium compounds such as ethyl lithium, n-butyl lithium (n-BuLi), isobutyl lithium), irithium polymethylene (eg 1,4-dirithiobutane) and the like. Lithium amides are also preferred as initiators because they can have polar groups at the ends of the chains of polymers that do not contain silanol functional groups or do not contain polysiloxane blocks with silanol ends. Lithium amides are obtained from secondary bicyclic or cyclic amines, in the latter case preference is given to using pyrrolidine and hexamethyleneimine, which amides are solvating agents (as described in French Patent No. 2,250,774). It can be solubilized in hydrocarbon solvents in combination with the use of solvating agents such as ethers. Representative barium containing compounds are described in the certificates of French Patent Application Nos. 2,302,311 and French Patent Application Nos. 2,273,822 and further French Patent Application Nos. 2,338,953 and French Patent Application Nos. 2,340,958, which are hereby incorporated by reference.

As is known per se, the polymerization is preferably, for example, aliphatic or cycloaliphatic hydrocarbons (eg pentane, hexane, heptane, isooctane, cyclohexane), or aromatic hydrocarbons (eg benzene, toluene or xylene) May be carried out in the presence of an inert solvent.

The polymerization can be carried out in a continuous or discontinuous process. The polymerization is generally carried out at a temperature of 20 ° C to 120 ° C, preferably at a temperature of 30 ° C to 90 ° C. Of course, it is also possible to add a transmetallation agent to the final polymerization in order to modify the reactivity of the living chain ends.

The functionalized diene polymers used in the present invention having silanol functional groups at the ends of the chain, or polysiloxane blocks comprising silanol ends, can be obtained by various processes by analogy. [Ref. Journal of Polymer Science, Part A, Vol. 3, pp. 93-103 (1965), the living diene polymer and the organosilane functionalizing agent are preferably the same outside the polymerization reactor to form a diene polymer having a halogenosilane functional group at the end of the chain. Or to react at different temperatures, preferably close to the polymerization temperature, and to obtain diene polymers functionalized with silanol at the ends of the chain, see "Chemistry and Technology of Silicones," Academic Press, New York, NY (1968), p. 95, which acts as a proton donor. These two reaction sequences are already described by Greber and Balciunas, Makromol. Chem. 69, pp. 193-205 (1963). Examples of organosilane functionalizing agents capable of reacting living diene polymers include the formula R ₁ R ₂ SiX ₂ , wherein R ₁ and R ₂ may be the same or different and are alkyl groups of 1 to 8 carbon atoms, and X is Mention may be made of linear dihalogenosilanes of halogen atoms, preferably chlorine or bromine).

As preferred dihalogenosilanes, mention may be made of dichloro-dimethylsilane, dichlorodiethylsilane, dichlorodiphenylsilane, dichlorophenylmethylsilane and dichlorovinylmethylsilane.

The second method consists of reacting the living polymer with a cyclic polysiloxane functionalizing agent to obtain a polymer having SiO-termination, wherein the reaction is carried out in a medium that does not allow polymerization of the cyclopoly-siloxane. Examples of cyclic polysiloxanes include chemical formulas (Wherein R ₁ and R ₂ may be the same or different and are alkyl groups of 1 to 8 carbon atoms, m is an integer of 3 to 8); mention may be made of hexamethyl as the preferred cyclic polysiloxane. Mention may be made of cyclotrisiloxane, trimethyltriethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, as well as mixtures thereof. The polymer having the SiO- terminus is then reacted with the proton donor compound to form a silanol functionalized diene polymer at the end of the chain.

The third method consists in producing a block copolymer comprising polysiloxane blocks having silanol ends by continuous polymerization. These block copolymers are described in US Pat. No. 3,483,270, US Pat. No. 3,051,684 and in J. Appl. Poly. Sci., Vol. 8, pp. 2707-2716 (1964) to prepare a first block of living diene polymer that reacts in a polar medium with anionic polymerized cyclic poly-siloxane, reacts with a proton donor (SiO— Can be obtained by forming a second block to form a block diene copolymer comprising polysiloxane blocks having silanol functional groups at the ends of the chain to finally obtain a continuous block copolymer comprising polysiloxane blocks having .

The fourth method involves grafting two polymers, for example irithiated or disolated polysiloxanes, onto a diene polymer having (SiX), where X is a halogen atom, followed by [ Reference: Makromal. Chem. 79, pp. 149-160 (1964), as described by Grabber and Valsiunas, or in Plumb and in the manual ("Block Copolymers," Applied Science, England (1973), p. 339). Block copolymer comprising polysiloxane blocks having silanol ends by reacting the grafted product with a proton donor to obtain a block copolymer comprising polysiloxane blocks having silanol ends as cited by Atherton It consists of preparing a.

The diene polymers modified along the chain by silanol functional groups can also be obtained by different processes, including, for example, first or third methods of first carrying out the metal exchange step of the polymer chains.

Of course, conventional techniques, such as agglomeration or vacuum evaporation, and then optionally drying and steam distillation of the solvent, to recover the functionalized polymer, may require addition of one or more antioxidants to the reaction mixture. This is surprising for those skilled in the art who would expect the development of macrostructures in the case of polymers functionalized by alkoxysilanes.

Functionalized diene polymers having silanol functional groups at the ends, or polysiloxane blocks having silane ends, or functionalized diene polymers modified along the chain by silanol functional groups, are carbon blacks having silica fixed to the surface as a reinforcing filler. It has a special ability to be used to form a rubber composition comprising.

The proportion of carbon black having silica fixed to the surface is at least 30 parts by weight of the polymer weight.

The carbon black having silica adhered to the surface can be used in blends with carbon black or white fillers, in particular other reinforcing fillers such as silica. The relative percentages of these fillers can be adjusted based on the trade-offs of the properties desired by those skilled in the art.

The amount of silica present on the carbon black surface is 0.1 to 50% by weight, preferably 0.3 to 30% by weight.

The carbon black described above in which silica is fixed on the surface can be obtained by different manufacturing methods. As an example thereof, the manufacturing method described in European Patent Application No. 0,711,805, Japanese Patent Application No. 63-63755, or the manufacturing method and patent application of ECOBLACK CRX2000 commercially available from CABOT Co. Mention may be made of the preparation methods described in WO96 / 37547.

Examples of suitable silicas for use in the present invention are all precipitated silicas or fumed silicas known to those skilled in the art, in particular highly dispersible silicas. The term “highly dispersible silica” is understood to be silica that can be highly deagglomerated and dispersed in a polymer mold, which can be observed by electron or optical microscopy on thin layers. In addition, the dispersibility of silica is tested in the ability to deagglomerate by ultrasound, followed by a paper published in European Patent Application No. 0,520,860 or in a periodical, the contents of which are incorporated herein by reference [Rubber World, June 1994, pages] 20-24, titled "Dispersibility Measurements fo Pres. Silicsa." To measure the medium diameter (D ₅₀ ) and the coagulation factor (F _D ) of the particles after deagglomeration. The particle size of the silica at is evaluated by measuring by diffraction.

Non-limiting examples of such silicas include Perkasil KS 430 from Akzo Company, Silicas Zeosil 1165MP and 85MP from Rhone-Poulenc, PPG. Mention may be made of silica HI-Sil 2000 from PPG CO., Silica Zeopol 8741 or 8745 from Huber Co.

Suitable for use as carbon black are commercially available carbon blacks or tires, especially all carbon blacks commonly used in tire treads. Non-limiting examples of the carbon black described above may include carbon black N 234, N 339, N 326, N 375 and the like.

In the compositions according to the invention, silanol functionalized or modified diene polymers are used alone or in other elastomers commonly used in tires, such as blends based on natural rubber or natural rubber and synthetic elastomers. Can be used as a blend with or used as a blend with other diene polymers that are coupled or starred or even partially or functionalized with functional groups other than silanol functional groups. Can be. In the compositions according to the invention it has been demonstrated that the higher the proportion of conventional elastomers, the less the improvement in their properties. This is because conventional elastomers may be present in an amount of from 1 to 50 parts by weight per 100 parts by weight of silanol functionalized or modified polymer.

In addition to one or more diene polymers and carbon blacks having silica adhered to the surface, the compositions according to the invention are suitable for all or several other constituents and for conventional additives used in rubber blends [e.g. Binders using antiozonant wax, sulfur and / or peroxide and / or bismaleimide based vulcanization systems, vulcanization accelators, expansion oils or elastomers and / or silica coatings ( Such as alkoxysilanes, polyols, amines, etc.).

The present invention also relates to a tire tread and a tire tread with reduced running resistance.

Description of the Preferred Aspects

The invention will be illustrated in a non-limiting manner by the following examples, which however do not limit the scope of the invention.

In the examples, the properties of the composition are evaluated as follows:

Mooney viscosity ML _{1 + 4} (100 ° C.), measured according to ASTM standard D-1646 and referred to in the table as “Money”;

The measurement is carried out according to Elongation modulus, ISO 37 at 300% (EM 300), 100% (EM 100) and 10% (EM 10);

Scott tear index, measured at 20 ° C. [rupture force (MPa), Fr; Rupture elongation (%), Er];

Hysteresis loss rate, measured in% at 60 ° C. The strain on the measured loss is 35%;

-Measure according to Shore A hardness, DIN 53505;

The measurement is carried out as a function of the kinetics at shear, strain from 10 to 23 ° C .;

Nonlinearity ㅿ G, expressed as MPa, is the difference in shear modulus that is between 0.15% and 50% of peak to peak strain;

Hysteresis is expressed as peak G "and peak tan δ measured according to ASTM D-2231-71 (reapproved in 1997) at 23 ° C. and strain of about 7%, with G ″ _{max23 ° C.} and tan δ _{max23 ° C.} Mark each one;

Volume resistivity ρ _v is measured in Ωcm according to ASTM D-257, with a value of 10 ⁵ to 10 ¹⁰ Ωcm. This is expressed in its log form relative to base 10 and denoted as Log resistivity.

Example 1

The purpose of this example is to characterize a composition based on a functionalized polymer having silanol functional groups in the chain, one based on the same polymer but one not functionalized and the other functionalized by known prior art functionalizing agents. In comparison to those of the two other compositions that have been oxidized, these three compositions comprise carbon black with silica adhered to the surface as a reinforcing filler.

In the tests of all examples, the diene polymer is a butadiene-styrene copolymer having 40% 1,2-butadiene bonds, 25% styrene, a glass transition temperature T _g of -38 ° C and a Mooney viscosity of 60.

Butadiene-styrene copolymers used in the three compositions are as follows:

Copolymer for Test A (SBR-A), having terminal silanol and functionalized for this purpose with a cyclic siloxane functionalizing agent consisting of hexamethylcyclotrisiloxane, D3;

A copolymer for test B, functionalized by known bisdiethylaminobenzophenone, DEAB, which allows to obtain a composition with good hysteresis using carbon black (SBR-B);

Unfunctionalized copolymer (SBR-C) for test C, suspended with methanol.

These SBRs are synthesized in a continuous process using butyl lithium as an initiator in toluene as the polymerization solvent. And for all the tests, the copolymer was continuously introduced with toluene, butadiene, styrene and THF in a mass ratio of 100: 10: 4.3: 0.3, and continuously with a solution of 500 μmol of active n-BuLi per 100 g of monomer, 32 liters with a turbine type stirrer are produced in an reactor of effective capacity. The flow rates of the different solutions are calculated to have an average residence time of 45 minutes during vigorous stirring. The temperature is kept constant at 60 ° C. At the outlet from the reactor, the conversion measured is 88% and the SBR comprises 25% styrene introduced and 40% 1,2-bond content to the butadiene moiety.

To obtain SBR-A, at the outlet from the reactor, hexamethylcyclo-trisiloxane (D3) in 0.48 ratio of D3 / active n-BuLi is added to the inlet of the static mixer. When synthesizing SBR-C, D3 is replaced with methanol in a 1.5 ratio of MeOH / active n-BuLi. When synthesizing SBR-B, DEAB is added instead of methanol in a 1.5 ratio of MeOH / active n-BuLi.

The molecular weight is measured by osmometry and then the functionalization rate (Fn) is calculated by ¹ H-NMR. In three cases, the molecular weight is 175,000 g · mol ⁻¹ . For functionalized polymer SBR-A, the functionalization rate is 80% when the number of milliequivalents per kilogram, corresponding to [-Si (CH ₃ ) ₂ OH] units, is 4.6, for functionalized polymer SBR-B The functionalization rate is 82 when the number of milliequivalents per kilogram, 4.7, corresponding to [(C ₂ H ₅ ) ₂ NC ₆ H ₄ ] ₂ COH units.

In the three cases above, after 5 minutes, 0.8 parts of 2,2'-methylene-bis (4-methyl-6-tert-butyl phenol) and 100 parts of N- (1, 0.2 pce of 3-dimethylbutyl) -N'-phenyl-p-phenylenediamine is added. The polymer is recovered by a conventional recovery method in which the solvent is steam distilled and then the polymer is dried in a cylindrical tool at 100 ° C. for 10 minutes.

Using three copolymers SBR-A, B and C, three reinforced by carbon black with silica adhered to the surface according to the following formulation (wherein all parts are expressed by weight) in a manner known per se: Rubber compositions A1, B1 and C1 are prepared:

Elastomer 100

Silica-treated carbon black ( ^* ) 60

Aromatic Oils 25

Binder ( ^** ) 1.8

Zinc Oxide 2.5

Stearic Acid 1.5

Antioxidant (a) 1.9

Paraffin (b) 1.5

Sulfur 1.1

Sulfenamide (c) 2

Diphenylguanidine 0.42

( ^* ) Carbon black with silica adhered to the surface is available from Kabot Corporation under the brand name NOIR ECOBLACK CRX2000 (% Si: 2.74% before HF treatment, 0.33% after HF treatment, specific surface area before HF treatment surface area, N2): 138.9 m 2 / g, specific surface area after HF treatment: 179.6 m 2 / g).

( ^** ) Polysulfated organosilanes sold by Degusa Corporation under the trade name SI69.

(a) Antioxidant: N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine.

(b) paraffins: mixtures of macrocrystalline waxes and microcrystalline waxes.

(c) sulfenamides: N-cyclohexyl-2-benzothiazyl sulfenamide.

The three copolymers described above are used to prepare the composition by the method described in European Patent Application No. 0,501,227 cited herein, which method employs the same maximum reduction while introducing the vulcanization system into the cylindrical tool at 30 ° C. It is embodied in a thermodynamic process consisting of carrying out two stages lasting 5 minutes and 4 minutes at an average paddle speed of 45 rpm until a temperature of 160 ° C. is obtained.

Vulcanization is carried out at 150 ° C. for 50 minutes. The properties of these three compositions are compared in both vulcanized and vulcanized states.

The results are shown in Table 1 below.

Composition A1D3 B1DEAB C1MeOH Properties in the Unvulcanized State ML _{1 + 4} (100 °) 86 87.5 75.5 Characteristics in vulcanized state Log resistivity shore EM10EM100EM300EM300 / EM100 9.3855.93.331.502.431.62 8.1458.84.151.562.321.49 7.9859.74.141.562.321.49 Scott 20 ℃ Fr20 ℃ Ar% 19.4420 23.7585 21.2530 PH 60 ℃ 19.7 24.4 26.1 Kinetic Characteristics as Deformation Function _{AtG at23 ℃} G " _{max23 °} tan δ _{max23 °} 0.950.400.23 2.290.700.29 2.600.830.33

Composition A1, based on SBR-A (silanol functionalized) in terms of properties in the vulcanized state, is low (G " _{max23 °} ; tanδ) without compromising other properties when compared to mixtures with SRB-C. _{max23 °)} it can be seen that show high (PH 60 ℃) strain is significantly more excellent hysteresis of the composition C1 comprises a SBR-C (suspended in methanol) in.

In addition, the properties of Composition A1 were better than those obtained with Composition B1 (SBR-B functionalized with DEAB).

Example 2

The object of this example is to provide a rubber composition according to the invention comprising, on the one hand, a silanol functionalized polymer and carbon black having silica fixed on its surface, a filler consisting of SBR-B and carbon black functionalized with DEAB. And to composition C2, which comprises SBR-C and a filler consisting of silica, a silanol coating and a coupling agent. It is known that these two final compositions, B2 and C2, have good hysteresis with carbon black and silica.

The preparation method used is the same as described in Example 1 for Composition C1.

These compositions have the following formulations:

Composition B2 Composition C2

Elastomer 100 Elastomer 100

Carbon Black N234 60 Silica ( ^* ) 60

Aromatic Oil 25 Aromatic Oil 25

Binder ( ^** ) 4.8

Zinc Oxide 3 Zinc Oxide 2.5

Stearic Acid 2 Stearic Acid 1.5

Antioxidant (a) 1.9 Antioxidant (a) 1.9

Paraffin (b) 1.5 paraffin (b) 1.5

Sulfur 1.2 Sulfur 1.1

Sulfenamide (c) 1.2 sulfenamide (c) 2

Diphenylguanidine 1.5

( ^* ) Silica: Zeiss 1165, commercially available from Rehon-Follen

( ^** ) Polysulfated organosilanes sold by Degusa Corporation under the trade name SI69.

The results are shown in Table 2.

Composition Stopper Filler Carbon black with A1D3 silica B2DEAB black C2MeOH Silica Properties in the Unvulcanized State ML _{1 + 4} (100 °) 86 90 68.5 Characteristics in vulcanized state Log resistivity shore EM10EM100EM300EM300 / EM100 9.3855.93.331.502.431.62 5.3604.441.512.021.34 > 1058.44.161.371.531.12 Scott 20 ℃ Fr20 ℃ Ar% 19.4420 22.7650 23.0705 PH 60 ℃ 19.7 30 26.1 Kinetic Characteristics as Deformation Function _{AtG at23 ℃} G " _{max23 °} tan δ _{max23 °} 0.950.400.23 4.841.250.36 1.880.580.25

Composition A1 (silanol functionalized SBR-A) comprising ecoblack CRX2000 as carbon black was significantly reduced by 30% without degrading other properties compared to that obtained for composition B2 based on carbon black. It can be seen that there is hysteresis (at low and high strains).

Moreover, it can be seen that Composition A1, which has significantly reduced conductivity, has significantly improved hysteresis properties compared to Composition C2 based on silica.

Example 3

In this example, SBR-A (functionalized with D3), SBR-C (stopped with MeOH) and SBR-B (with no binder, but carbon black with silica fixed on the surface as reinforcing filler) 3 compositions A3, C3 and B3 based on DEAB functionalized).

Compositions A3, C3 and B3 are prepared by the method described in Example 1 and have the following formulation:

Elastomer 100

Silica-treated carbon black ( ^* ) 60

Aromatic Oils 25

Binder 0

Zinc Oxide 2.5

Stearic Acid 1.5

Antioxidant (a) 1.9

Paraffin (b) 1.5

Sulfur 1.1

Sulfenamide (c) 2

Diphenylguanidine 0.42

( ^* ) Carbon black with silica adhered to the surface is available from Carbot Corporation under the brand name Neuer Eco Black CRX2000 (% Si: 2.74% before HF treatment, 0.33% after HF treatment, specific surface area (N2) before HF treatment: 138.9㎡ / g, specific surface area after HF treatment: 179.6 m 2 / g).

The results are summarized in Table 3.

Composition A3D3 B3DEAB C3MeOH Properties in the Unvulcanized State ML _{1 + 4} (100 °) 88.2 91.5 76.5 Characteristics in vulcanized state Log resistivity shore EM10EM100EM300EM300 / EM100 8.5253.33.101.231.801.46 7.0957.34.131.321.651.25 6.7958.14.351.301.611.24 Scott 20 ℃ Fr20 ℃ Ar% 21.5575 21.9670 20.8685 PH 60 ℃ 22.9 28.8 33.4 Kinetic Characteristics as Deformation Function _{AtG at23 ℃} G " _{max23 °} tan δ _{max23 °} 1.100.450.25 3.030.780.38 3.830.970.38

Composition A3 using SBR-A (silanol functionalized) without the use of coatings and binders has different properties when compared to the other two compositions that also include carbon black having silica fixed on the surface as a reinforcing filler. It can be seen that it has very low hysteresis at low (G " _{max23 ° C} ; tanδ _{max23 ° C} ) and high (PH 60 ° C) strains without breaking.

Moreover, the hysteresis properties of compositions B3 and C3 based on SBR-B and SBR-C respectively, compared to compositions B2 and C2 of Example 2 based on the same polymer including coating and binder, On the contrary, the hysteresis properties of composition A3 are mostly as good as those of composition A1, including the coating and the binder.

It should also be emphasized that other properties such as mechanical cohesion (EM300) force, elongation at break, and the like of composition A3 are not reduced, while the conductivity is not reduced compared to composition A1.

Example 4

The purpose of this example is to compare the compositions A1 and C1 of Example 1 based on SBR and silanol functionalized SBR stopped with methanol, respectively, with compositions F1 using the same formulation but with different SBRs.

The SBR-F described above is synthesized by a continuous process as in Example 1 using cyclohexane as the polymerization solvent and hexamethyleneimine lithium (HMINLi) as the initiator. It is functionalized by hexamethylcyclotrisiloxane (D3), and the method for preparing composition F1 is the same as that used for compositions A1 and C1.

The results are shown in Table 4.

Catalyst stopper A1BuLiD3 C1BuLiMeOH F1HMIMLiD3 Properties in the Unvulcanized State ML _{1 + 4} (100 °) 86 75.5 120 Characteristics in vulcanized state Log resistivity shore EM10EM100EM300EM300 / EM100 9.3855.93.331.502.431.62 7.9859.74.141.562.321.49 1058.13.711.722.701.57 Scott 20 ℃ Fr20 ℃ Ar% 19.4420 21.2530 19.6415 PH 60 ℃ 19.7 26.1 18.0 Kinetic Characteristics as Deformation Function _{AtG at23 ℃} G " _{max23 °} tan δ _{max23 °} 0.950.400.23 2.600.830.33 0.930.390.21

In terms of properties in the vulcanized state, composition F1 using silanol functionalized SBR-A and using a catalyst different from composition A1, when better properties than those obtained using composition A1 are not obtained It can be seen that the hysteresis properties at low and high strains are much improved and also superior when compared to that of the composition C1 based on SBR-C stopped with methanol.

Thus, improving hysteresis properties without destroying other properties, obtained by using silanol functionalized polymers in the presence of reinforcing fillers consisting of carbon black with silica fixed on the surface, is independent of the choice of catalyst. It seems obvious.

Example 5

The purpose of this example is to compare the composition G5 according to the invention with the other two compositions H5 and I5 based on commercially available SBRs.

Compositions G5, H5 and I5 are synthesized by discontinuous processes, each based on the following SBRs:

SBR-G is synthesized in cyclohexane in a discontinuous process and functionalized by D3 according to the following method;

T0589, commercially available from JAPAN SYNTHETIC RUBBER Co., is a polymer that has been specifically modified to react with silica and has the following characteristics: T _g = -32 ° C,% 1,2 = 41 %,% sty = 33%, ML _{1 + 4} (100 °) = 45;

NS116, commercially available from NIPPON ZEON Co., is a polymer specifically modified to react with carbon black and has the following characteristics: T _g = -25 ° C.,% 1,2 = 60%, % sty = 21%, ML _{1 + 4} (100 °) = 50;

SBR-G is synthesized in a discontinuous process as follows.

Into a 10 L reactor containing 4.6 L of degassed cyclohexane, 211 g of styrene, 429 g of butadiene and 2000 ppm of THF are injected. After impurity is neutralized with n-BuLi, 0.001 mol of sodium tert-butylate and 0.0033 mol of n-BuLi used as randomizing agents are added, and the polymerization is carried out at 55 ° C.

When the conversion reaches 90%, 0.0011 mol of hexamethylcyclotrisiloxane (D3) is injected into the reactor. The polymerization solution is stirred at 55 ° C. for 15 minutes. 0.80 pce of 2,2-methylene-bis (4-methyl-6-tert-butylmethylphenol) and 0.20 pce of N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine were added to the polymer. Antioxidant is added, recovered by steam distillation and dried in a cylindrical tool at 100 ° C.

The Mooney viscosity (ML _{1 + 4} 100 °) is 46, the mass percentage (% sty) of incorporated styrene, measured by ¹ H-NMR, is 33%, and the proportion of vinyl chains in the butadiene portion (% 1,2). ) Is 41%.

NMR analysis showed that the [-Si (CH ₂ ) ₂ ] -OH functionalization rate, 4mEq./kg, accounting for the molecular weight (175,000 g / mol) of the copolymer as indicated by the osmotic system, was [SiOH ] Corresponds to about 70% functionalization rate.

The three compositions G5, H5 and I5 have the same formulation as specified in Example 1, based on EcoBlack CRX2000, which is carbon black with silica fixed on its surface, and the process for preparing these compositions is also described in Example 1. Same as used for Composition A1.

The results are shown in Table 5.

Composition SBR G5SBR-G H5T0589 I5NS116 Properties in the Unvulcanized State ML _{1 + 4} (100 °) 109 56 48 Characteristics in vulcanized state Log resistivity shore EM10EM100EM300EM300 / EM100 1056.83.581.712.981.74 7.8458.64.391.722.601.51 7.4859.84.471.702.491.46 Scott 20 ℃ Fr20 ℃ Ar% 22.6445 23.3535 20.8515 PH 60 ℃ 17.5 29.0 29.1 Kinetic Characteristics as Deformation Function _{AtG at23 ℃} G " _{max23 °} tan δ _{max23 °} 1.030.5260.266 2.470.09510.341 2.600.9770.364

With regard to the properties in the vulcanized state, it can be seen that only composition G5 based on SBR-C according to the present invention can obtain very low hysteresis and very low reinforcement properties.

Therefore, when a specific functionalized polymer applied to carbon black is used in a polymer based on silica treated carbon black (in this case, ECOBLACK CRX2000), it is impossible to improve hysteresis characteristics and physical properties, and silica treatment as a reinforcing filler It seems impossible to improve the properties by displacing a polymer specifically functionalized for silica in a composition comprising the carbon black.

Claims (11)

At least one diene polymer, characterized in that the diene polymer is a functionalized diene polymer having a silanol function at the end of the chain, or a polysiloxane block having silanol ends, or a diene polymer modified along the chain by the silanol function; A vulcanized rubber composition comprising carbon black having silica fixed on its surface as a reinforcing filler. The polysiloxane block of claim 1 wherein the polysiloxane block is of the formula [-(SiR ₁ R ₂ O) _x -H], wherein R ₁ and R ₂ are the same or different and are alkyl groups of 1 to 8 carbon atoms, and x is 1 to It is an integer in the range of 1500) having a silanol end. The composition of claim 2 wherein R ₁ and R ₂ are alkyl groups having 1 to 5 carbon atoms, preferably methyl groups. The composition of claim 1 wherein the diene polymer is a butadiene-styrene copolymer or a butadiene-styrene-isoprene copolymer. The composition of claim 4 further comprising polybutadiene and / or butadiene-isoprene copolymer and / or natural rubber. The composition of claim 1, wherein the amount of silica present on the surface of the carbon black is 0.1 to 50% by weight. The composition of claim 6, wherein the amount of silica present on the surface of the carbon black is 0.3 to 30% by weight. The composition of claim 1 wherein carbon black having silica fixed to the surface is used in a blend with other reinforcing fillers. At least one diene polymer, characterized in that the diene polymer is a functionalized diene polymer having a silanol function at the end of the chain, or a polysiloxane block having silanol ends, or a diene polymer modified along the chain by the silanol function; A tire comprising a vulcanized rubber composition comprising carbon black having silica fixed to a surface as a reinforcing filler. 10. The tire of claim 9, wherein the rubber composition constitutes a tire tread. At least one diene polymer, characterized in that the diene polymer is a functionalized diene polymer having a silanol function at the end of the chain, or a polysiloxane block having silanol ends, or a diene polymer modified along the chain by the silanol function; A tire tread comprising a vulcanized rubber composition comprising carbon black having silica adhered to the surface as a reinforcing filler.