Chemically treated fillers and polymeric compositions containing same

ES 2 328 664 T3

DESCRIPTION

Chemically treated fillers and polymer compositions containing them.

Description of the invention

The present invention relates to chemically treated fillers and the use of such fillers in polymer compositions. More particularly, this invention relates to particulate or amorphous fillers having minimal carbon and mercapto contents, minimal Silane Conversion Index, minimal Standard Reinforcement Index, and polymers, eg, curable rubber compositions, containing such charges. Very particularly, this invention relates to a functionalized hydrophobic filler, hereinafter referred to as "modified filler", which improves the production efficiency of polymeric compositions, as is the case when composing rubbers, and the behavior of products. polymerized or cured, eg tires.

In the production of polymeric compositions it is common to incorporate reinforcing fillers to improve the physical properties of the polymer. Frequently, the surfaces of such polymers are modified to increase the reactivity and, consequently, the two-dimensional and three-dimensional coupling of the filler within the polymer composition. In the rubber industry it is common to incorporate carbon black and other reinforcing fillers into natural and synthetic rubber to increase the physical properties of the curable rubber vulcanizate. Fillers used to reinforce such polymer compositions include natural and synthetic fillers.

One of the main non-black fillers used in the rubber industry is amorphous precipitated silica. This siliceous filler is used to impart improved tensile strength, tear resistance, and abrasion resistance to the rubber vulcanizate. Silica fillers are also used in combination with carbon black to obtain maximum mileage in passenger vehicles and tires for off-road use, for example, tires for mining and extraction operations in forests, and for construction equipment of roads. When used as the sole reinforcing filler, silica fillers that are not well dispersed in the rubber do not impart the improved overall performance that is obtained using only carbon black. This is most easily seen in rubber vulcanizates used for tires, eg tire treads.

Various coupling agents, eg titanates, zirconates and silanes, have been suggested for use with fillers when such fillers are incorporated into polymeric compositions, eg rubber, in order to improve the performance of the rubber vulcanizate. Among the various organosilane coupling agents suggested for use are mercaptoalkyltrylakoxysilanes, eg, mercaptopropyltrimethoxysilane. It has been found that the use of an appropriate amount of such coupling agents, in particular mercaptopropyltrimethoxysilane, in filler reinforced synthetic rubbers provides at least equivalent performance to carbon black reinforced synthetic rubbers in several key physical properties such as 300% modulus, tensile strength, abrasion resistance and heat expansion.

The high cost of mercaptoalkyltrialkoxysilanes, the irritating odors associated with net materials, and the time and energy required to mix them into rubber compositions have banished the more general use of siliceous fillers as the primary reinforcing filler in high volume applications. Rubber. US Patent No. 4,136,847 describes increasing the effectiveness of silane coupling agents, particularly mercaptosilane coupling agents, using an alkoxysilane in combination with the silane to form a coupling composition. In a specific embodiment described in the '847 patent, the silane coupling composition is formulated with the siliceous filler in a suitable non-reactive liquid that is chemically inert with respect to the coupling composition and the siliceous filler to prepare a compounding additive. rubber, that is, a silica-silane concentrate.

US Patent No. 5,116,886 describes a two-step process in which the surface of oxide or silicate fillers, natural or synthetic, is modified using certain organosilicon compounds. In the first stage, the organosilicon compound is mixed intensively with the filler at a temperature below 60 ° C. In the second stage, the homogeneous mixture is subjected to a temperature of 60 to 160 ° C to complete the modification of the surface of the load.

US Patent No. 5,908,660 also describes a two-step process for the preparation of hydrophobic silica. In the first step, an aqueous suspension of precipitated silica is contacted with an organosilicon compound in the presence of a catalytic amount of an acid to impart hydrophobicity to the precipitated silica. In the second step, the aqueous suspension of the precipitated hydrophobic silica is contacted with a water-immiscible organic solvent in a solvent to silica weight ratio greater than 5: 1 to effect separation of the precipitated hydrophobic silica from the phase. watery.

The present invention relates to a filler comprising an amorphous or particulate inorganic oxide chemically treated in an aqueous suspension at a pH of 2.5 or less with a combination of a mercaptoorganometallic reactant and a sulfur-free organometallic compound in a weight ratio of at least 0.05: 1, thereby increasing the pH from 3 to 10 after the completion of the chemical treatment, in which.

ES 2 328 664 T3 (a) the mercaptoorganometallic reactant is represented by the following graphic formula I

<img file="ES2328664T3_D0001.tif" />

where L is halogen or -OR⁷, Q is hydrogen, Ci-i2 alkyl or halo-substituted Ci-i2 alkyl, R⁶ is Ci_i2 alkylene, R⁷ is C alkyl_1-12 or alkoxy-alkyl containing from 2 to 12 carbon atoms, the mentioned groups being halogen (or halo) chlorine, bromine, iodine or fluorine, and n is 1, 2 or 3, and in which the hydrogen atom of mercapto can be replaced by an unsaturated heteroatom or carbon; or (b) the mercaptoorganometallic reactant is replaced by a combination of the mercaptoorganometallic reactant from (a) and a different organometallic sulfur-containing compound in a weight ratio of mercaptoorganometallic compound to organometallic sulfur-containing compound of at least greater than 1: 1;

(c) the sulfur-free organometallic compound is selected from the group consisting of organometallic compound (s) represented by formula II:

^Rito^MX(4_a) organometallic compound (s) represented by formula III:

^R22c + 2^Yesc^OR(c_I) organometallic compound (s) represented by formula IV:

^R32d^Yesd^ORd

II

III

IV organometallic compound (s) represented by formula V:

(R²3Si) kNR⁴(3_k) and a mixture of said organometallic compounds; wherein each M is, independently, a silicon, titanium, or zirconium atom; each Rⁱ is independently a hydrocarbon group of 1 to 18 carbon atoms; or Rⁱ is an organofunctional hydrocarbon group of 1 to 12 carbon atoms, the said functionality comprising amino, carboxylic acid, carbinol ester or amido; each X is independently selected from the group consisting of halogen, amino, alkoxy groups of 1 to 12 carbon atoms and acyloxy groups of 1 to 12 carbon atoms; a is an integer 1,2 or 3; each R² is, independently, halo, hydroxy or a hydrocarbon group containing from 1 to 18 carbon atoms with the proviso that at least 50 mol% of the R substituents² are hydrocarbon groups containing 1 to 18 carbon atoms; c is an integer from 2 to 10,000; each R³ is, independently, halo, hydroxy, or a hydrocarbon group containing from 1 to 18 carbon atoms and d is an integer from 3 to 20; each R⁴ is independently hydrogen or a hydrocarbon group containing 1 to 18 carbon atoms and k is 1 or 2; and said halo or halogen is selected from chlorine, fluorine, bromine or iodine, which has (a) a carbon content greater than 1 percent by weight and (b) a mercapto content greater than 0.15 percent by weight ( c) a Silane Conversion Index of at least 0.3 as defined herein and (d) a Standard Reinforcement Index of at least 4 as defined herein.

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The procedure described in US patent no. 5,908,660 can be improved and used to produce the modified filler of the present invention by using a certain combination of functionalizing and hydrophobicizing agents in an inorganic oxide aqueous suspension having a pH of 2.5 or less and treating the acidic aqueous suspension of Modified fillers with acid neutralizing agents to increase the pH of the suspension to a range of 3.0 to 10.

As used herein, a functionalizing agent is a chemical that can cause an inorganic oxide to covalently bind to the polymeric composition in which it is used. A hydrophobicizing agent is a chemical that can bind to and / or associate with an inorganic oxide to such an extent that it causes a reduction in the water affinity of the inorganic oxide while increasing the affinity of the inorganic oxide to the organic polymer composition in which it's used.

The mentioned Standard Reinforcement Index (ERI) of at least 4 or higher indicates a modification of the interaction or bonding between the components of the filler-polymer composition. Specifically, there is a stronger interaction between filler and polymer and / or polymer and polymer than is usually present for a given amount of filler-filler interaction. Stated alternatively, there is a weaker charge-charge interaction than is usually present for a given amount of charge-polymer and / or polymer-polymer interaction. Appropriate modifications of these interactions in a rubber composition have been reported to result in lower rolling resistance, better traction on snow, and lower noise generation. In addition to the improved properties, the modified filler has the benefit of requiring less time and energy to incorporate into the polymer composition.

Detailed description of the invention

The modified filler of the invention is an inorganic oxide having a carbon content greater than 1% by weight, preferably at least 1.5% by weight, and more preferably at least 2.0% by weight; a mercapto content greater than 0.15% by weight, preferably at least 0.3% by weight, and more preferably at least 0.5% by weight; a Silane Conversion Index of at least 0.3, preferably at least 0.4, and most preferably at least 0.5, and a Standard Reinforcement Index of at least 4.0, preferably at least 4 , 5, and most preferably at least 5.0. The modified filler of the present invention may be further characterized by a tensile strength for 300% elongation of at least 6.2, preferably at least 7.0, more preferably at least 7.5, and most preferably at least 8.0. The modified filler of the present invention can be further characterized by a Brunauer-Emmett-Teller (BET) specific surface area of ​​20 to 350 m²/ g, preferably 40 to 300 m²/ g and most preferably 100 to 200 m²/ g, a pH of 5 to 10, preferably 5.5 to 9.5, more preferably 6.0 to 9.0, and most preferably a pH of 6.5 to 7.5 or the pH of the product it can vary between any combination of these values, including the indicated ranges; and a Soxhlet extractable carbon percentage of less than 30%, preferably less than 25%, and more preferably less than 20%, for example 15%. Procedures for determining the aforementioned characteristics of the modified filler are described in Example 15.

The filler used to prepare the modified filler of the present invention is an inorganic oxide defined herein as any solid particulate or amorphous material that possesses oxygen (chemisorbed or covalently bound) or hydroxyl (bound or free) on its exposed surface. Furthermore, inorganic oxide is a material that is suitable for use in the different molding, compounding or coating processes, including injection molding, lamination, transfer molding, compression molding, rubber compounding, coating (such as dipping , brushing, knife coating, roller coating, silk mesh coating, printing and spray coating) and casting.

The inorganic oxide or the mixture of 2 or more inorganic oxides used to produce the modified filler of the present invention can be natural or synthetic. Such charges include the oxides of the metals of periods 2, 4, 5 and 6 of groups Ib, IIb, IIIa, IIIb, IVa, IVb (except carbon), Va, VIa, VIIa and VIII of the periodic table. of the elements published in "Advanced Inorganic Chemistry: A Comprehensive Text", by F. Albert and others, 4^to edition, John Wiley and Sons, 1980. Among the natural silicates kaolins and clays are especially suitable. However, kieselguhr or diatomaceous earth can also be used. As fillers there may be named, by way of example, aluminum oxide, aluminum hydroxide or aluminum trihydrate, and titanium dioxide, which can be obtained from natural deposits. Especially suitable synthetic fillers are aluminosilicates, silicates, fumed, colloidal and precipitated silicas.

The term "aluminosilicates" can be described as natural or synthetic materials in which the silicon atom of a silicon dioxide is replaced or substituted, naturally or synthetically, by aluminum atoms. For example, 5 to 90%, alternatively 10 to 80% of the silicon atoms of a silicon dioxide can be replaced, or substituted, naturally or synthetically, by silicon atoms, resulting in an aluminosilicate. A suitable process for such a preparation can be described, for example, as co-precipitation by adjusting the pH of a basic solution or mixture of silicate and aluminate; also as chemical reaction between SiO₂, or silanols on the surface of a silicon dioxide, and NaAlO₂. For example, in such a coprecipitation process, the coprecipitated aluminosilicate may have 5 to 95% of its surface comprised of silica moieties and correspondingly 95 to 5% of its surface comprised of aluminum moieties.

ES 2 328 664 T3

Examples of aluminosilicates include muscovite, beryl, dichroite, sepiolite, and kaolinite. Examples of synthetic aluminosilicates include zeolites and those which may be represented, for example, by the formulas [(Al₂OR₃)_x(SiO₂)_Y- (H₂OR)_z], [(To the₂OR₃)_x(SiO₂)_YYO], where Y is magnesium or calcium.

Preferably, the inorganic oxide used to produce the modified filler of the present invention is aluminosilicate, colloidal silica, precipitated silica, or mixtures thereof, and most preferably it is precipitated silica of the type commonly used for compounding with rubber. The group of various commercially available silicas that may be considered for use in the present invention includes the silicas commercially available from PPG Industries under the Hi-Sil trademark under the designations 210, 243, etc .; silicas available from Rhone-Poulenc, under the designations of, for example, Z1165MP and Z165GR and silicas available from Degusta AG under the designations of, for example, VN2 and VN3.

The precipitated silica used to produce the precipitated filler of the present invention can be produced, for example, by acid precipitation of silicate solutions, for example sodium silicate. The process of preparing the precipitated silica is not limiting in the present invention and will depend on the desired properties of the silica, such as the specific surface area and the particle size required for a given application.

The BET surface area of ​​the precipitated silica used in the preparation of the modified silica of the present invention will generally be in the range of 50 µm.²/ g at 1000 m²/ g and preferably it will be in the range of 100 m²/ g at 500 m²/ g.

The precipitated silica used to form modified silica may be in the form of an aqueous suspension of the production steps preceding the drying step, such as a suspension formed during precipitation or a reliquefied filter cake. The suspension can also be formed by redispersing dried silica in an aqueous and / or organic solvent. The concentration of hydrophilic silica precipitated in the aqueous and / or organic suspension is not critical and may be in the range of about 1 to 90% by weight. Preferably, the concentration of precipitated hydrophilic silica is within a range of 1 to 50% by weight, more preferably 1 to 20% by weight.

The Silane Conversion Index is defined by the equation T7 (T '+ T²+ T³). The values ​​of T¹, T² and T³ are determined by NMR ²⁹ Si and represent reacted silane units. The Silane Conversion Index provides an indication of the degree of crosslinking of the silane to adjacent Si atoms and to each other. The higher the Index, the greater the amount of crosslinking between silanes, the silica surface and adjacent silanes. T¹ represents a silane unit chemically bonded in one place to the surface of silica or to another silane. T² represents a silane unit chemically bonded at two sites to an Si atom on the silica surface and an adjacent silane, two adjacent silanes, or to two adjacent surface Si atoms, ie partially cross-linking structures. T³represents a silane unit chemically attached to three sites, or to a silicon atom, on the surface of silica and two adjacent silanes, or to two Si atoms and a silane unit or to three silane units.

It is believed that those skilled in the coupling agent art can develop an Organometallic Reactant Conversion Index, comparable to the Silane Conversion Index, and use it to achieve an indication of the degree of reaction or crosslinking of zirconates and / or titanates (alone or in combination with silanes) with the inorganic oxide and with each other.

The Standard Reinforcement Index is determined using a Standard Compose Protocol. The Standard Composing Protocol described herein does not include the addition of free or unbound coupling agents to the rubber batch. This is an important distinction since others have recently reported Reinforcement Rates, that is, modulus ratios at 300% / 100%, greater than 4.0. See US patents no. 5,846,311 and no. 5,876,494. In both patents, a silica / rubber coupling agent was added during silane compounding, Silane X 50-S. Typically, the addition of such coupling agents to a rubber batch requires more time to mix when compounding.

Polymeric compositions, eg, plastics and / or resins, to which the modified filler can be added, include essentially any plastic and / or resin. Rubber compounds are included in this definition. Such polymers are described in the Kirk Othmer Encyclopedia of Chemical Technology, 4^toedition, 1996, vol. 19, pp. 881-904, description incorporated herein by reference. The modified filler can be mixed with the polymer or its polymerizable components, while the physical form of the polymer or polymerizable components is any liquid or compostable form, such as a solution, suspension, latex, dispersion or the like. The polymer compositions containing the modified filler can be ground, mixed and cured in any manner known in the art, to form a polymeric article having 10 to 150 parts of the modified filler polymer dispensed therein. Suitable polymers include, by way of example, thermoplastic and thermosetting resins, rubber compositions, and other polymers having elastomeric properties.

The polymers can be alkyd resins, oil-modified alkyd resins, unsaturated polyesters, natural oils (eg linseed, tung, soy), epoxides, nylons, thermoplastic polyesters (eg, polyethylene terephthalate, polybutylene terephthalate), polycarbonates, namely thermoplastics and thermosets, polyethylenes, polybutylenes, polystyrenes, polypropylenes, ethylene-propylene copolymers and terpolymers, acrylics (homopolymers

ES 2 328 664 T3 and copolymers of acrylic acid, acrylates, methacrylates, arcrylamides, their salts, hydrohalides, etc.), phenolic resins, polyoxymethylene (homopolymers and copolymers), polyurethanes, polysulfones, polysulfide rubbers, nitrocelluloses, butyrate vinyl , vinyls (polymers containing vinyl chloride and / or vinyl acetate), ethyl cellulose, cellulose acetates and butyrates, viscose rayon, shellac, waxes, ethylene copolymers (for example, ethylene vinyl acetate copolymers, ethylene acrylic acid copolymers, ethylene acrylate copolymers), organic rubbers, silicone greases, resins and rubber, and the like.

The amount of modified filler that can be used in the polymeric compositions can vary from 5 to 70% by weight in relation to the total weight of the plastic composition. For example, the typical amount of modified filler used in an ABS (acrylonitrile-butadiene-styrene) copolymer is 30 to 60% by weight, in an acrylonitrilestyrene-acrylate copolymer it is 5 to 20% by weight, in aliphatic polyketones it is 15 to 30% by weight, in alkyd resins (for paints and inks) it is 30 to 60% by weight, in thermoplastic olefins it is 10 to 30% by weight, in epoxy resins it is 5 to 20% by weight, in ethylene-vinyl acetate copolymers it is up to 60% by weight, in ethylene ethyl acetate copolymers it is up to 80% by weight, in liquid crystalline polymers (LCP) it is 30 to 70% by weight, in phenolic resins it is 30-60% by weight and in polyethylene usually the amount is greater than 40% by weight.

Organic rubber and silicone rubber are particularly preferred. Examples of such rubbers are natural rubber; those formed by homopolymerization of butadiene and its homologues and derivatives such as: cis-1,4polyisoprene, 3,4-polyisoprene; cis-1,4-polybutadiene; trans-1,4-polybutadiene; 1,2-polybutadiene; and those formed by copolymerization of butadiene and its homologues and derivatives with one or more polymerizable monomers containing ethylenic unsaturation such as styrene and its derivatives, vinylpyridine and its derivatives, acrylonitrile, isobutylene and alkyl substituted acrylates such as methyl methacrylate. Examples include styrene-butadiene copolymer rubber comprised of various percentages of styrene and butadiene and in which the various isomers of butadiene are employed as desired (hereinafter "SBR"); styrene terpolymers, isoprene and butadiene polymers, and their various isomers; acrylonitrile-based copolymers and terpolymer rubber compositions; and isobutylene-based rubber compositions; or a mixture thereof as described, for example, in US Patent Nos. 4,530,959, no. 4,616,065, no. 4,748,199, no. 4,866,131, no. 4,894,420, 4,925,894, no. 5,082,901 and no. 5,162,409.

Other suitable organic polymers are copolymers of ethylene with other higher alpha olefins such as propylene, butene-1 and pentene-1 and a diene monomer. Organic polymers can be block, random or sequential and can be prepared by polymerization processes in emulsion (eg SBR-e), solution (eg SBR-s). Additional polymers that can be used include those that are partially or fully functionalized, including coupled or star branched polymers. Additional specific examples of functionalized organic rubbers include polychloroisoprene, chlorobutyl, and bromobutyl rubber, as well as brominated isobutylene-paramethylstyrene rubber. The preferred organic rubbers are polybutadiene, SBR-s, and mixtures thereof.

Examples of silicone rubbers include organic polysiloxane compositions in which the organic polysiloxane is linear or branched and may optionally contain, in addition to hydrocarbon groups, certain reactive groups such as, for example, hydroxyl, hydrolyzable groups, alkenyl groups. such as vinyl, hydrogen, fluorine, or phenyl. More examples are given in US Patent No. 5,009,874 in column 5, line 27 to column 6, line 23.

Preferably, the polymeric composition is a curable rubber. The term "curable rubber" includes natural rubber and its various raw and recovered forms as well as synthetic rubbers. For example, curable rubber could include combinations of SBR and butadiene rubber (BR), SBR, BR and natural rubber and any other combinations of materials previously described as organic rubbers. In describing this invention, the terms "rubber", "elastomer" and "rubber-like elastomer" can be used interchangeably, unless otherwise indicated. The terms "rubber composition", "compound rubber" and "rubber compound" are used interchangeably to refer to rubber that has been mixed or combined with various ingredients and materials, such terms being well known to those skilled in the art. of mixing or compounding rubber.

The modified filler of the present invention can be prepared using step A alone or both steps A and B to prepare hydrophobic silica and fumed silica, described in US Pat. 5,908,660 and no. 5,919,298, respectively, with the following changes. The amount of acid used gives a pH of 2.5 or less in the aqueous suspension, preferably a pH of 2.0 or less, more preferably a pH of 1.0 or less, and most preferably a pH of 0, 5 or less; The modifying chemical used is a combination of a mercaptoorganometallic reactant and a non-sulfur-containing organometallic compound, hereinafter referred to as a sulfur-free organometallic compound, in a weight ratio of a mercaptoorganometallic reactant to a sulfur-free organometallic compound of at least 0.05: 1, preferably 0.05: 1 to 10: 1, more preferably 0.1: 1 to 5: 1 and most preferably 0.2: 1 to 2: 1, for example 0 , 5: 1 to 1: 1, or the weight ratio can vary between any combination of these values, inclusive of the indicated values; and after the end of the chemical treatment, the acidity (added or generated in situ by the hydrolysis of halogenated organometallic compounds) is neutralized. Typically, upon completion of the chemical treatment reaction, the pH of the resulting aqueous suspension is increased to a pH range of 3 to 10. Neutralizing agents can be of any type typically used to raise the pH of an acidic solution as long as the properties of the modified filler are not adversely affected. Suitable neutralizing agents include sodium hydroxide, potassium hydroxide, ammonium hydroxide, and sodium bicarbonate. The neutral

The modified filler can also be carried out by adding ammonia gas to the aqueous solution during spray drying.

The acid used in step (A) can be of many types, organic and / or inorganic. The preferred acid catalyst is inorganic. Examples of acid catalysts include hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, nitric acid, phosphoric acid, and benzenesulfonic acid. An acid catalyst or a mixture of two or more acid catalysts can be used, as desired. When the organometallic reactant is, for example, a chlorosilane, the catalytic amount of the acid can be generated in situ by hydrolysis of the chlorosilane or the reaction of the chlorosilane directly with hydroxyls of the inorganic oxide.

The temperature at which step (A) is carried out is not critical and is usually in the range of 20 ° C to 250 ° C, although, when desired, somewhat lower or somewhat higher temperatures can be used. The reaction temperature will depend on the reactants used, eg, the organometallic compound (s), the acid and, if used, a cosolvent. Preferably, step (A) is carried out at temperatures in the range of 30 ° C to 150 ° C, although step (A) can be carried out, if desired, at the reflux temperature of the suspension used in step ( TO).

The initial step of contacting the acidic aqueous suspension of inorganic oxide with a combination of mercaptoorganometallic compound and organometallic compound without sulfur may further include adding a water-miscible solvent in sufficient quantity to facilitate its reaction with the inorganic oxide. The solvent acts as a phase transfer agent that accelerates the interaction of the combination of the hydrophobic and non-sulfur organometallic sulfur compounds with the hydrophilic inorganic oxide. When used, the amount of water-miscible organic solvent will typically comprise at least 5% by weight of the aqueous suspension, more preferably 15 to 50% by weight, and most preferably 20 to 30% by weight of the aqueous suspension. , or the weight percent may vary between any combination of these values, inclusive of the indicated values. Suitable water-miscible solvents include, for example, alcohols such as ethanol, isopropanol, and tetrahydrofuran. Preferably, isopropanol is used as the water-miscible organic solvent.

A surfactant can also be used in the initial stage, either in combination with the water-miscible organic solvent or instead of the water-miscible organic solvent, in an amount sufficient to facilitate the chemical modification of the inorganic oxide by the mercapto-organometallic compound and the compound without sulfur. The surfactant can be nonionic, anionic, cationic, amphoteric, or a mixture of such surfactants, as long as it does not have an adverse effect on the performance of the resulting chemically modified inorganic oxide in its intended use. Typically, when used, the surfactant is employed at a level of 0.05 to 10% by weight of the aqueous suspension, more preferably 0.1 to 5% by weight, and most preferably 0.1 to 3%. by weight, or the weight may vary between any combination of these values, inclusive of the indicated values.

Representative examples of suitable surfactants include alkylphenol polyglycol ethers, eg, p-octylphenol polyethylene glycol (20 units) ether, p-nonylphenol polyethyllenglycol (20 units) ether, alkylpolyethylene glycol ethers, eg, dodecyl polyethylene glycol (20 units) ether, polyglycol ether, , for example, polyethylene glycol 2000, salts of alkyltrimethylammonium, for example, chloride (or bromide) of cetyltrimethylammonium, salts of dialkyldimethylammonium, for example, dilauryldimethylammonium chloride, alkylbenzyltrimethylammonium salts, alkylbenzenesulfonates, eg sodium p-dodecylbenzenesulfonate, sodium p-nonylbenzenesulfonate, alkyl hydrogen sulfates, eg lauryl hydrogen sulfate, and alkyl sulfates, eg lauryl sulfate. The surfactant can also be, for example, a polysiloxane polymer or copolymer having an allyl end-blocked polyethylene oxide.

The mercaptoorganometallic compound used to produce the modified filler of the present invention is represented by the following graphic formula I:

<img file="ES2328664T3_D0002.tif" />

where M is silicon, L is halogen, or -OR⁷, Q is hydrogen, Ci-i2 alkyl, halosubstituted Ci-i2 alkyl, R⁶ is Ci_i2 alkylene, R⁷ is C1-12 alkyl or alkoxyalkyl containing from 2 to 12 carbon atoms, said groups being halogen (or halo) chlorine, bromine, iodine or fluorine, and n is 1, 2 or 3. Preferably, R⁶ is CI-3 alkylene, for example methylene, ethylene and propylene, R⁷ preferably is CI-4 alkyl, more preferably methyl and ethyl, L is preferably -OR⁶ and n is preferably 3. Mercapto-organometallic reactants having two mercapto groups can also be used.

Mercaptoorganometallic compounds in which the mercapto group is blocked can also be used. Blocked mercaptoorganometallic compounds have an unsaturated heteroatom or a directly attached carbon

ES 2 328 664 T3 to sulfur via a single bond. Examples of specific blocking groups include thiocarboxylate ester, dithiocarbamate ester, thiosulfonate ester, thiosulfate ester, thiophosphate ester, thiophosphonate ester, thiophosphinate ester, etc.

When reaction of the mixture is desired to couple the filler to the polymer, an unblocking agent is added to the mixture to unblock the mercaptoorganometallic compound. If water or alcohol is present in the mixture, a catalyst, for example tertiary amines, Lewis acids or thiols, can be used to initiate and promote the loss of the blocking group by hydrolysis or alcoholysis to liberate the corresponding mercaptoorganometallic compounds. Procedures for preparing and using such compounds, eg, blocked mercaptoorganometallic compounds, are set forth in PCT application WO 99/09036. Other procedures for preparing blocked mercaptosilanes are disclosed in US Pat. 3,692,812 and no. 3,922,436.

Examples of useful organometallic compound (s) include, but are not limited to, mercaptomethyltrimethoxysilane, mercaptoethyl-trimethoxysilane, mercaptopropyltrimethoxysilane, mercaptomethyltriethoxysilane, mercaptoethyltrypropoxysilane, mercaptothylaptylanoxy (ethylaptylanoxysilane (ethylaptylanoxysilane) mercaptomethyl) methyldiethoxysilane, 3-mercaptopropylmethyldimethoxysilane and mixtures thereof. The most preferred compounds are mercaptopropyltrimethoxysilane, mercaptopropyltriethoxysilane, or mixtures thereof.

Examples of useful blocked mercaptosilanes include, but are not limited to, 2-triethoxysilyl-1-ethyl thioacetate, 3-trimethoxysilyl-1-propyl thioacetate, bis- (3-triethoxysilyl-1-propyl) methyl thiophosphonate, 3-triethoxysilyl-1-propyldimethyl, 3-triethoxysilyl-1-propylmethyl thiosulfate, 3-triethoxysilyl-1-propylmethyl toluene-thiosulfonate, and mixtures thereof.

The sulfur-free organometallic compounds that can be used to produce the modified filler of the present invention may be at least one sulfur-free organometallic compound or a mixture of sulfur-free organometallic compounds selected from the group consisting of: organometallic compound (s) represented by formula II:

(d)

IOIX ..._:II organometallic compound (s) represented by formula III:

R²2c + 2^Yesc ^OR(c-1) fR organometallic compound (s) represented by formula IV:

R³2dSidOdIV organometallic compound (s) represented by formula V:

(R²3 Yes) kNR⁴(3-k) V where each M is, independently, a silicon, titanium or zirconium atom; each R¹ is independently a hydrocarbon group of 1 to 18 carbon atoms; or R¹ is an organofunctional hydrocarbon group of 1 to 12 carbon atoms, said functionality being, for example, amino, carboxylic acid, carbinol ester or amido; each X is independently selected from the group consisting of halogen, amino, alkoxy groups of 1 to 12 carbon atoms and acyloxy groups of 1 to 12 carbon atoms; a is the integer 1, 2 or 3; each R² is, independently, halo, hydroxy or a hydrocarbon group containing from 1 to 18 carbon atoms with the proviso that at least 50 mol% of the R substituents² are hydrocarbon groups containing 1 to 18 carbon atoms; c is an integer from 2 to 10,000; each R³ is, independently, halo, hydroxy, or a hydrocarbon group containing from 1 to 18 carbon atoms and d is an integer from 3 to 20; each R⁴ is independently hydrogen or a hydrocarbon group containing 1 to 18 carbon atoms and k is 1 or 2; and the mentioned group (s) halogen or (halo) is selected from chlorine, bromine, iodine or fluorine. In the definition of the substituents shown in formulas II, III, IV and V, like symbols have the same meaning, unless otherwise indicated.

In formula II, each R¹ It can be a saturated or unsaturated monovalent hydrocarbon group or a substituted or unsubstituted monovalent hydrocarbon group.¹ it can be, for example, alkyl groups such as methyl, ethyl, propyl, isopropyl, isobutyl, t-butyl, n-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl and dodecyl; alkenyl groups such as vinyl, allyl, and hexenyl; substituted alkyl groups such as chloromethyl, 3,3,3-trifluoropropyl and 6-chlorohexyl; cycloalkyl groups such as cyclohexyl and cyclooctyl; aryl groups such as phenyl and naphthyl; and substituted aryl groups such as benzyl, tolyl, and ethylphenyl.

ES 2 328 664 T3

When X is a halogen in formula II, it is preferred that the halogen is chlorine. When X is an alkoxy group, it can be, for example, methoxy, ethoxy and propoxy. When X is an acyloxy group, it can be, for example, acetoxy. It is more preferred to select each X from the group consisting of chlorine and methoxy.

The viscosity of the aforementioned organometallic compounds is not limiting and can vary between that of a fluid and that of a rubber. Generally, the higher molecular weight organometallic compounds will be cleaved by the acidic conditions of the chemical modification step, whereby they can react with the hydrophilic inorganic oxide.

In formulas III, IV, and V, each R¹, R² and R³ can be the same as the hydrocarbon groups described for R¹. For the purposes of the present invention, when the organometallic reactant is an organosilicon reactant, the silicon is considered to be a metal.

Preferably, the sulfur-free organometallic compound (s) is (are) represented by formulas II, III, IV, V or a mixture of the aforementioned organometallic compounds in which M is silicon. More preferably, the sulfur-free organometallic compound is represented by formula II wherein R¹ is C alkyl_1-6, X is chlorine and a is 2.

Examples of useful organosilicon compounds include, but are not limited to, compounds and mixtures of compounds selected from the group consisting of diethyldichlorosilane, allylmethyldichlorosilane, methylphenyldichlorosilane, phenylethyldiethoxysilane, 3,3,3-trifluoropropylmethyldichlorosilane, trimethylbutoxyldichlorosilane, trimethylbutoxyldichlorosilane, siminyldichlorosilane, trimethylbutoxyldichlorosilane, trimethylbutoxyldichlorosilane, syminyloxytracyloxanyl octamethylcyclo-tetrasiloxane, hexaethyldisiloxane, pentylmethyldichlorosilane, divinyldipropoxysilane, vinyldimethylchlorosilane, vinylmethyldichlorosilane, vinildimetilmetoxisilano, trimetilcloro-silane, trimethylmethoxysilane, trimethylethoxysilane, methyltrichlorosilane, methyltrimethoxy silane, methyltriethoxysilane, hexamethyldisiloxane, hexenilmetildiclorosilano, hexenyl-dimethyldichlorosilane, dimethylchlorosilane, dimethyldichlorosilane, dimethyldimethoxysilane, dimethyldiethoxysilane, hexamethyldisilazane, triviniltrimetilciclotrisilazano, polydimethylsiloxanes comprising 3 to about 20 dimethylsiloxy units and trimethylsiloxy or hydroxydimethylsiloxy end-blocked poly (dimethylsilosiloxane) polymers having an apparent viscosity within the range of 1 to 1,000 mPa at 25 ° C.

Examples of organotitanium compounds that can be used include, but are not limited to, Ci_i8 tetraalkoxy titanate, methyltriethoxytitanium (iv), methyltitanium triisopropoxide (iv), methyltitanium tributoxide (iv), methyltitanium tri-tbutoxide (iv), isopropyl titanium (iv), butyl titanium triethoxide (iv), butyl titanium tributoxide (iv), phenyl titanium triisopropoxide (iv), phenyl titanium tributoxide (iv), phenyl titanium triisobutoxide (iv), [Ti (CH₂Ph)₃(NC₅H1o)] and [Ti (CH2SiMe3) 2mU

Examples of compounds that can be used include, but are not limited to, tetraalkoxy C_1-18 zirconate, phenylzirconium trichloride (iv), methylzirconium trichloride, ethylzirconium trichloride (iv), propylzirconium trichloride (iv), methylzirconium tribromide (iv), ethylzirconium tribromide (iv), propylzirconium tribromide (iv), propylzirconium tribromide (iv) iv). Zirconium compounds similar to those described above are also contemplated for organotitanium compounds and vice versa.

The amount of mercaptoorganometallic compound and organometallic compound without sulfur used in the aforementioned chemical modification process is the amount that is sufficient to produce a modified filler characterized by a carbon content greater than 1% by weight, a mercapto content greater than 0 , 15% by weight, a Silane Conversion Index of at least 0.3 and a Standard Reinforcement Index of at least 4.0. Such an amount is referred to herein as a coupling amount, that is, an amount sufficient to bind the filler and allow the modified filler to bind to the polymer composition.

The weight ratio of mercaptoorganosilane to sulfur-free organometallic compound will range from at least 0.05: 1, preferably from 0.05: 1 to 10: 1, more preferably from 0.1: 1 to 5: 1, and most preferably from 0.2: 1 to 2: 1, for example 0.5: 1 to 1.1, or the weight ratio can vary between any combination of these values, inclusive of the indicated values. The individual organometallic reactants can be added together or sequentially in any order. It is preferred to add the reactants in an amount that provides an excess of organometallic units relative to the hydroxyl groups available for reaction on the inorganic oxide particles. The upper limit of the amount of organometallic reactants added to the process is not critical. Excess mercaptoorganometallic compounds and non-sulfur organometallic compound can be removed by filtration, distillation, washing with a solvent or any other known separation techniques.

In another embodiment, the mercaptoorganometallic reactant may be replaced by a combination of a mercaptoorganometallic compound and a different organometallic sulfur-containing compound in a weight ratio of mercaptoorganometallic compound to organometallic sulfur-containing compound of at least greater than 1: 1, for example, 1 , 01: 1. The ratio can range from 1.01: 1 to 100: 1, preferably 5: 1 to 50: 1, and more preferably 10: 1 to 30: 1, or the weight ratio can vary between any combination of these values, inclusive of the indicated values. Any organometallic sulfur-containing compound (other than the mercaptoorganometallic compound represented by formula I) that acts as a coupling agent is useful in the vulcanization of a filler-containing rubber.

ES 2 328 664 T3

Examples of useful sulfur-containing organometallic compounds include bis (alkoxysilylalkyl) polysulfides described in US Pat. 3,873,489 and no. 5,580,919, the description of which is incorporated herein by reference, and which are represented by the following formula VII:

Z-alk-S_n, -alq-Z (VII)

<img file="ES2328664T3_D0003.tif" />

wherein alk is a divalent hydrocarbon radical having 1 to 12, preferably 1 to 6, and more preferably 2 to 3 carbon atoms; n 'is an integer from 2 to 12, preferably 2 to 6, and more preferably 3 to 4, and Z is

Rr '. / / Si — R ·, O \ X

R * R 'where R is an alkyl group having 1 to 4 carbon atoms or phenyl, and R' is an alkoxy group having 1 to 8, preferably 1 to 4, more preferably 1 to 2 carbon atoms, a cycloalkoxy group with 5 to 8 carbon atoms, or a straight or branched chain alkylmercapto group with 1 to 8 carbon atoms. The groups R and R 'can be the same or different. The divalent alk group can be straight or branched chain, a saturated or unsaturated aliphatic hydrocarbon group, or a cyclic hydrocarbon group. The high purity organosilanedisulfides disclosed in US Pat. 5,580,919 require the percentage of n 'in formula I to be 2.

Examples of bis (alkoxysilylalkyl) polysulfides include: bis (2-trialkoxysilylethyl) polysulfides in which the trialkoxy group is trimethoxy, triethoxy, tri (methylethoxy), tripropoxy, tributoxy, etc. up to trioctyloxy, and the polysulfide is di-, tri-tetra-, penta- and hexasulfide. The corresponding bis (3-trialkylalkoxysilylpropyl) -, bis (3-trialkoxysilylisobutyl) -, bis (4-triaalkoxysilylbutyl) -, etc. can also be used. up to bis (6-trialkoxysilylhexyl) -polysulfide. Organosilanes of relatively simple structure are preferred, including bis (3-trimethoxy-, triethoxy- and tripropoxy-silylpropyl) polysulfides, namely di-, tri- and tetrasulfides.

Specific examples of bis (alkoxysilylalkyl) polysulfides are described in column 6, lines 5-55 of the aforementioned US Pat. 3,873,489 and at column 11, lines 1-41 of US Patent No. 5,580,919. Representative examples of such compounds are:

3,3'-bis (trimethoxysilylpropyl) disulfide,

3,3'-bis (triethoxysilylpropyl) tetrasulfide,

3,3'-bis (trimethoxysilylpropyl) tetrasulfide,

2,2'- bis (triethoxysilylethyl) tetrasulfide,

3,3'- bis (trimethoxysilylpropropyl) trisulfide,

3,3'- bis (triethoxysilylpropyl) trisulfide,

3,3'- bis (triebutoxysilylpropyl) disulfide,

3,3'-bis (trimethoxysilylpropyl) hexasulfide and

3,3'-bis (trioctoxysilyl) tetrasulfide and mixtures thereof. The most preferred compound is 3,3'-bis (triethoxysilylpropyl) tetrasulfide (TESPT)

TESPT is available under the trade name Si-69 from Degussa Corp. It has been found to be a mixture of:

3,3'-bis (triethoxysilylpropyl) monosulfide,

3,3'-bis (triethoxysilylpropyl) disulfide,

3,3'-bis (triethoxysilylpropyl) trisulfide,

3,3'-bis (triethoxysilylpropyl) tetrasulfide and higher sulfide homologues having an average sulfide of 3.5.

After the end of the chemical modification process, the pH of the aqueous suspension of the modified inorganic oxide is increased from the pH 2.5 or less of the treatment to a pH of 3.0 to 10.0. Typically, the pH of the

ES 2 328 664 T3 resulting aqueous solution is increased to 3 or more, preferably 4 or more, more preferably 5 or more, and most preferably 6 or more and usually 10 or less, preferably 9 or less , more preferably 8 or less, and most preferably 7 or less. The pH of the aqueous suspension can vary between any combination of these levels, including the indicated levels. This is done to neutralize added or generated acidity and produce a final product (after drying) that has a pH of 5.0 to 10.0.

The modified inorganic oxide is recovered by filtration and drying or by contacting the aqueous suspension of the modified inorganic oxide with a water-immiscible organic solvent in a weight ratio of solvent to inorganic oxide of greater than 1 to 1, preferably greater than 5 to 1. The modified inorganic oxide recovered in the solvent phase can be used without purifying or drying it. A contemplated embodiment of the present invention is a composition comprising a suspension of the modified filler in a water-immiscible solvent. T = concentration of the modified filler in the suspension can vary from 1 to 90% by weight in relation to the total weight of the suspension.

Examples of useful water immiscible organic solvents are low molecular weight siloxanes such as hexamethyldisiloxane, octamethylcyclotetrasiloxane, diphenyltetramethyldisiloxane and trimethylsiloxy end-blocked polydimethylsiloxane fluids. When a siloxane is used as a solvent, it can act as a solvent and as a reactant with the inorganic oxide. In addition, useful water-immiscible organic solvents include aromatic hydrocarbons such as toluene and xylene; heptane and other aliphatic hydrocarbon solvents; cycloalkanes such as cyclohexane; ethers such as diethyl ether and dibutyl ether; halohydrocarbon solvents such as methylene chloride, chloroform, ethylene chloride, and chlorobenzene, and ketones such as methyl isobutyl ketone.

The water-immiscible organic solvent used to contact the aqueous suspension of hydrophobic particles may or may not contain one or more materials dissolved therein, as desired. Examples of such materials include, but are not limited to, one or more rubbers, oil, coupling agent, antioxidant, and accelerator.

The modified filler of the present invention (as powder, granule, pellet, paste, aqueous suspension or suspension in solvent) can be combined with a base material, that is, a material used in the product to be manufactured to form a so-called masterbatch. . The modified filler may be present in a masterbatch in a higher concentration than in the final product. During mixing operations, aliquots of this mixture are typically added in production scale quantities in order to aid in the uniform dispersion of very small amounts of such additives to polymer compositions, for example, plastics, rubbers, and polymer compositions. coating.

The modified filler can be combined with emulsion and / or solution polymers, for example organic rubber comprising a styrene / butadiene solution (SBR), polybutadiene rubber, or a blend thereof, to form a masterbatch. One contemplated embodiment is a masterbatch comprising a combination of organic rubber, water immiscible solvent, modified filler, and optionally processing oil. This product can be supplied by a rubber producer to a tire manufacturer. The benefit to the tire manufacturer of using a masterbatch is that the modified filler is evenly distributed throughout the rubber, resulting in minimized mixing time to produce the compound rubber. The masterbatch may contain 10 to 150 parts of modified silica per 100 parts of rubber (phr), preferably 20 to 130 phr, more preferably 30 to 100 phr, and most preferably 50 to 80 phr.

In another embodiment of the present invention, a polymer article is contemplated having 10 to 150 parts of modified filler dispensed therein per 100 parts of polymer, preferably 20 to 130, more preferably 30 to 100, and most preferably of 50 to 80 parts modified filler per 100 parts polymer. Alternatively, the amount of modified charge may vary between any combination of these values, inclusive of the indicated ranges. As described herein, the polymer can be selected from the group consisting of thermoplastic resins, thermosetting resins, organic rubber, and silicone rubber. Preferably the polymer is a curable organic rubber.

Curable rubbers primarily contemplated for use in combination with the modified filler of the present invention are well known to those skilled in the art of rubber chemistry and include vulcanizable and sulfur curable rubbers. In particular those that are typically used for mechanical rubber products are contemplated.

The modified filler of the present invention can be mixed with a vulcanizable rubber-like elastomer by conventional means such as a Banbury mixer or a rubber mill at a temperature of 38 ° C to 150 ° C. A vulcanizable rubber composition may contain, relative to 100 parts of vulcanizable rubber polymer, 10 to 150 parts of modified filler, preferably 20 to 130 phr, more preferably 30 to 100 phr, and most preferably 50 to 80 pcc. Other conventional rubber additives present are conventional sulfur or peroxide cure systems.

The sulfur cure system can include 0.5 to 3 parts sulfur, 2 to 5 parts zinc oxide, and 0.5 to 2 parts accelerator. The peroxide cure system can include 1 to 4 parts of a peroxide such as dicumyl peroxide. Other conventional rubber additives can also be used. The group of such additives

ES 2 328 664 T3 includes other fillers such as carbon black, oils, plasticizers, accelerators, antioxidants, heat stabilizers, light stabilizers, zone stabilizers, organic acids such as, for example, stearic acid, benzoic acid or salicylic acid, other activators, extenders and coloring pigments. The particular compounding recipe will vary with the vulcanized preparation, but such recipes are well known in the rubber compounding art.

The vulcanizable rubber composition is vulcanized or cured to rubber vulcanizate according to special procedures known in the rubber industry. Examples of industrial rubber vulcanizates (articles) that can be produced using the modified filler of the present invention include wire and cable sleeves, hoses, clamping rings and seals, automotive and industrial conveyor belts, machine assemblies, V-belts, roller liners, tires and pneumatic components such as treads, belt supports, tire housings, tire sidewalls, tire tread edges, tire bed loads and tire wire lining, shoe sole materials, packing rings, shock absorber elements and many others.

The present invention is more particularly described in the following discussion of the Standard Protocol for Composing. The Examples and Comparative Examples are illustrative only and those skilled in the art will identify numerous variations and modifications thereof.

Standard Protocol for Composing

The Standard Protocol for Compounding was used to prepare test samples of formulated rubber compositions containing the silica of Examples and Comparative Examples (EC)

Part A

The following ingredients in amounts of parts per hundred parts by weight of rubber (pcc) were added in the order described to a polyethylene bag held upright in a 500 milliliter plastic cup:

<td>Material</td><td>Quantity, pcc</td>

<td>Processing oil¹</td><td> 30,0</td>

<td>Zinc oxide²</td><td> 2,5</td>

<td>Antiozonant³</td><td> 2,0</td>

<td>Stearic acid⁴</td><td> 1,0</td>

<td>Silica sample</td><td> 12,5</td>

1. Sundex® 8125, aromatic hydrocarbon processing oil, commercially obtained from Sun Company, Inc., Refining and Marketing Division.

2. Kadox®, surface treated zinc oxide, commercially obtained from Zinc Corportion of America.

3. Wingstay® Antiozonant, a mixture of diaryl p-phenylenediamines, obtained commercially from The Goodyear Tire &amp; Rubber Co.

Four. Stearic acid, rubber grade, commercially obtained from CP Hall.

Part b

A 1.89 liter Farrel Banbury (model "BR") mixer was used to mix the various ingredients. Immediately before adding the batch ingredients to the mixer, 800 grams of CV-60 grade natural rubber was put through the mixer to clean it of any residue from previous batches and increase the temperature to approximately 93 ° C. After removing the rubber, the mixer was cooled to approximately 65 ° C before adding the ingredients to produce the rubber test sample.

A rubber composition was prepared using the test silica, the other ingredients listed below, and the procedure described below.

ES 2 328 664 T3

<td>Ingredient</td><td>Quantity, pcc</td><td>Time in minutes when material was added to the mixer ((or removed))</td><td>Rotation speed rpm</td>

<td>First pass SBR rubber⁵</td><td> 70,0</td><td> 0</td><td> 116</td>

<td>BR rubber⁶</td><td> 30,0</td><td> 0</td><td> 116</td>

<td>Test silica</td><td> 57,5</td><td> 0,5</td><td> 116</td>

<td>Sample of Part A</td><td>All</td><td> 3,0</td><td> 116</td>

<td>Download contents</td><td></td><td> ((5,0))</td><td></td>

<td>Second pass</td><td></td><td></td><td></td>

<td>Product of the first</td><td>Everything</td><td> 0</td><td> 77</td>

<td>pass</td><td></td><td></td><td></td>

<td>Antiozonant⁷</td><td> 2,0</td><td> 0</td><td> 77</td>

<td>Petroleum wax⁸</td><td> 1,5</td><td> 0</td><td> 77</td>

<td>Sulfur RM⁹</td><td> 1,4</td><td> 0,5</td><td> 77</td>

<td>TBBS¹⁰</td><td> 1.7</td><td> 0,5</td><td> 77</td>

<td>DPG¹¹</td><td> 2,0</td><td> 0,5</td><td> 77</td>

<td>Download contents</td><td></td><td> ((4,0))</td><td></td>

5. Solflex® 1216, Styrene Butadiene Rubber (SBR) solution, commercially available from The Goodyear Tire &amp; Rubber Co.

6. Budene 1207, butadiene rubber (BR), obtained commercially from The Goodyear Tire &amp; Rubber Co.

7. Santoflex® Antiozonant, described as N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine.

8. Okering® 7240, microcrystalline wax / paraffin blend commercially available from Astor Corporation.

9. Sulfur Rubber Makers (RB), 100% active, commercially obtained from Taber, Inc.

10. Nt-butyl-2-benzothiazolesufenamide, commercially obtained from Monsanto.

eleven. Diphenylguanidine, commercially available from Monsanto.

The first pass was started by adding the rubber, namely SBR and BR, to the mixer and mixing at 116 rpm for 0.5 min. The rotor speed was maintained at 116 rpm and 57.5 phr of the treated silica sample was added. After an additional 1.5 minutes the ram was raised and the chute swept, that is, the inlet chute cover was lifted and returned to the mixer sweeping away the material found in the chute. After one minute the Part A sample was added. After another minute the ram was raised and the chute swept. The contents of the mixer were mixed for an additional minute to achieve a maximum temperature in the range of 145 to 150 ° C and complete the first pass in the mixer. Depending on the type of sample, the mixer rotor speed can be increased or decreased after 4 minutes to achieve a temperature in the aforementioned Range in the specified mixing period.

ES 2 328 664 T3

After completing the first pass, the temperature of the material was measured with a thermocouple to verify that it did not exceed the maximum temperature of 150 ° C. The removed material was weighed and rolled on a two roll rubber sheeter at 2.032mm ± 0.127mm. The resulting laminated stock was cut into strips in preparation for the second pass in the mixer.

Between the end of the first pass and the beginning of the second pass, a minimum of one hour was allowed for the stock to cool down. If necessary, before starting the second pass, the process described before cleaning and heating was completed using CV-60 quality natural rubber. The mixer temperature was adjusted to approximately 49 ° C. Circulating the cooling water, the second pass was started by adding the stock strips from the first pass to the mixer operating at 77 rpm and the previously weighed combination of Santoflex® 13 antiozonant and the Okerin® 7240 microcrystalline wax / paraffin mixture. After 0.5 min, the second combination of RM Sulfur, TBBS and DPG was added. After an additional 1.5 minutes, the ram was raised and the weir swept. The second pass was completed by mixing the stock for an additional 2.0 minutes while the temperature was maintained at or below 125 ° C.

Part c

A 12 inch two roll Farrel rubber sheeter was heated to about 60 ° C. Stock from the second pass of Part B was supplied to the rolling mill with a roll gap set at 2.032mm ± 0.127mm. The resulting sheet was put on a flat surface until the temperature of the sheet reached room temperature. Typically, the sheet cooled in about 30 min. Then the rolled sheet was supplied to the rubber sheeter with a roll gap set at 3.81 mm ± 0.51 mm. The rolling bed was adjusted, if necessary, to maintain a uniform thickness. The resulting material was subjected to 16 side cuts and then 8 final passes. The roll spacing was adjusted to produce a sheet thickness of 2.032mm ± 0.127mm. The collected leaf stock was placed on a clean flat surface. A 203.2mm x 152.4mm rectangular sample was cut from the sheet stock using a template. The sample was conditioned, that is, it was stored between clean polyethylene sheets and kept for 15 to 18 hours at a temperature of 23 ° C ± 2 ° C and a relative humidity of 50% ± 5%.

After conditioning, the sample was placed in a standard steel compression mold of a 203.2mm x 152.4mm x 2.286mm machine frame having a polished surface. The sample was cured in a 61 cm x 61 cm, 890 kilonewton, electrically heated compression press at T90, that is, the time it takes for 90% cure to occur, in accordance with ASTM D- 2084, plus 5 minutes at 150 ° C under a pressure of 13.79 megapascals. Typically, cure was complete in about 10 minutes. The resulting cured rubber sheet was removed from the mold and held for 15 to 18 hours at a temperature of 23 ° C ± 2 ° C and a relative humidity of 50% ± 5% prior to testing for Part D.

Part d

The test was performed in accordance with ASTM D-412-98a - Test Procedure A. Dumbbell-shaped test specimens were prepared using the punch D. An Instron Model 4204 apparatus with automatic contact extensometer was used to measure elongation. The speed of the crosshead was found to be 508 mm / min. All calculations were done using the Series IX Automated Materials Testing software supplied by the manufacturer. The Reinforcement Index is equal to the tensile strength for a 300% elongation (in MPa) divided by the tensile strength for a 100% elongation (in MPa). When the specimens were prepared using the Standard Protocol for Composing, the results are expressed as the Standard Reinforcement Index.

Precipitated Silica Preparation

A precipitated silica was produced by acidifying a sodium silicate solution with sulfuric acid. Most of the precipitate occurred at a pH above 8.5. Further precipitate was produced by continuing the acid addition until the solution reached a pH of 3.3 to 4.0.

A sample of the silica precipitated for specific surface analysis, as described in Example 15, was subjected to filtration and washing of a portion of the silica until the rinse water had a conductivity level of approximately 600 to 800 microhoms. . The resulting filter cake was reliquidated using a high shear stirrer to form a solid-in-liquid suspension. The suspension was dried in a Niro spray drier (inlet temperature about 360 ° C and outlet temperature about 110 ° C). Table 1 shows the specific surfaces used to prepare the modified silicas of the Examples and Comparative Examples.

ES 2 328 664 T3

Examples 1-6

Approximately 50 kg of the precipitated silica, of which approximately 3.25 kg is silica, and 15.2 to 15.9 kg of isopropyl alcohol were added to a 115 L glass-lined vessel with bottom drain. The vessel was also equipped with a temperature recorder, a mechanical stirrer, a means for heating, and a condenser.

While the contents of the container were stirred and heating was initiated, 3-mercaptopropyltrimethoxysilane (MPTMS) was added over a time interval, (typically about 10 minutes), which would give the approximate amounts given in Table 1 in percentages. by weight of MPTMS per silica on a dry basis. The MPTMS / DMDCS weight ratios are also given in Table 1. The resulting pH was in the range of about 1.5 to about 2.2.

After the addition of DMDCS was completed, an amount of concentrated hydrochloric acid was added, that is, approximately 37% by weight, necessary to reduce the pH of the solution to approximately 0.3. The mixture was heated to approximately 6 ° C and held at this temperature for approximately 30 minutes. While cooling, sufficient 50% NaOH was added to the mixture over a time interval to adjust the pH to about 3.5. Upon completion of the NaOH addition, sufficient toluene (typically 6.75 to 7.75 kg) was added to the stirring mixture to effect separation of the precipitated hydrophobic silica from the aqueous phase without forming an emulsion. The aqueous phase was drained from the container.

The stirred mixture in the vessel containing the precipitated hydrophobic silica was then washed with about 30 kg of water. Sufficient additional toluene (typically 6.5 to 8.0 kg) was added to the stirring mixture to effect separation of the hydrophobic precipitated silica from the aqueous phase without forming an emulsion. The aqueous phase was drained. The stirred mixture containing the hydrophobic precipitated silica was then washed two more times with about 30 kg of water for each wash. After each wash, before adding the next wash, the aqueous phase was drained from the container.

After the wash was complete, enough toluene (typically 12.5 to 15.3 kg) was added to the stirring mixture to make a slidable solid-in-liquid suspension that could be easily discharged from the container. The resulting suspension was dried in a rotocone dryer under vacuum (minimum 585 mm of mercury) at 140 ° C minimum. Drying was continued until the sample revealed a percent weight loss of less than 4% when exposed to 160 ° C for 10 minutes.

Example 7

The procedure described in Examples 1-6 was followed except for the following: 80 g of 3-mercaptopropyltrimethoxysilane (MPTMS) was added over approximately 10 min; 487 g of dimethyldichlorosilane were added over approximately 10 min; isopropyl alcohol and toluene were not used and the suspensions from the three batches were combined, filtered and washed with water until the wash water had a conductivity level of approximately 300 to 800 microsiemens The treated silica sample was dried until a sample had a weight loss &lt;2% by weight when exposed to 160 ° C for 10 minutes.

The approximate weight percentages of MPTMS and DMDCS per silica on a dry basis and the weight ratio of MPTMS / DMDCS for the modified silica sample of Example 7 are given in Table 2.

Example 8

The procedure described in Examples 1-6 was followed except for the following: 40 kg of a solid reliquidated in a liquid suspension of precipitated silica (3.3 kg of silica) and 12.2 kg of isopropyl alcohol were used; 171 g of 3-mercapto-propyltrimethoxysilane (MPTMS) were added over about 7 minutes; 506 g of dimethyldichlorosilane (DMDCS) were added over about 2 minutes; concentrated hydrochloric acid was added over 24 minutes resulting in a solution having a pH of about 0.4; After heating the solution for 30 minutes at about 68 ° C, enough 50% by weight NaOH was added to adjust the pH to about 7.0; Sufficient toluene (about 7.1 kg) was added to effect separation of the hydrophobic silica from the aqueous phase without forming an emulsion. The recovered product was not washed with water, but after draining the aqueous phase, about 2.2 kg of toluene was added to the product to make a slidable solid in liquid suspension. The treated silica sample was dried until one sample had a weight loss &lt;2% by weight when exposed to 160 ° C for 10 minutes.

The approximate weight percentages of MPTMS and DMDCS per silica on a dry basis and the weight ratio of MPTMS / DMDCS for the modified silica sample of Example 8 are given in Table 2.

ES 2 328 664 T3

Example 9

The procedure of Example 8 was followed except 86.5 g of 3-mercaptopropyltrimethoxysilane (MPTMS) was used. The approximate weight percentages of MPTMS and DMDCS per silica on a dry basis and the weight ratio of MPTMS / DMDCS for the modified silica sample of Example 9 are given in Table 2.

Examples 10-13

Both silanes (DMDCS and MPTMS) and enough acid (to result in a pH of about 0.3) were mixed with a freshly prepared suspension of silica having a temperature of about 85 ° C immediately prior to adding it to the container. The acid used was concentrated, that is, sulfuric acid of about 96% by weight in all cases except Example 13, in which concentrated hydrochloric acid was used. The resulting mixture was allowed to stand for at least 15 minutes. Water was added and stirred, adjusting the pH to about 3.5 with 50% by weight aqueous sodium hydroxide solution. The resulting aqueous suspension of hydrophobic silica was filtered and washed with water until the rinse water had a conductivity level of about 300 to 800 microsiemens. The hydrophobic silica was dried until a sample had a weight loss of less than 2.5% when exposed to 160 ° C for 10 minutes. The approximate amounts of the silanes added to the suspension are given in Table 2 in percent by weight relative to dry silica together with the weight ratios of MPTMS / DMDCS.

Example 14

The procedure of Examples 10-13 was followed, except that no acid was added, only the acid generated by the hydrolysis of DMDCS being present. Sufficient MPTMS and enough dimethyldichlorosilane (DMDCS) were added to give the weight percentages of each per silica on a dry basis given in Table 2. The pH of the resulting solution was 1.6.

Comparative Examples 1-3

The procedure described for Examples 1-6 was followed. The approximate amounts of the silanes added to the suspension are given in Table 2 in weight percent relative to dry silica together with the MPTMS / DMDCS weight ratios.

Comparative Example 4

The procedure of Examples 10-13 was followed, except that only mercaptopropyltrimethoxysilane was added to result in an approximate weight percent of MTPMS per dry silica given in Table 2, and enough concentrated sulfuric acid was added to result in a pH of about 0.0.

Comparative Example 5

The procedure of Comparative Example 4 was followed, except that only dimethyldichlorosilane was added to result in an approximate weight percent of DCDMS per dry silica given in Table 2, and enough concentrated sulfuric acid was added to result in a pH of about 0 ,4.

Example 15

The specific surface area of ​​the treated and untreated silica test samples from Examples 1-14 and Comparative Examples (EC) 1-5 was determined using a 6200 series Horiba instrument by a dynamic single spot specific surface technique, procedure C modified from ASTM D3037-93. This procedure simulates the Brunauer-Emmett-Teller (BET) procedure to P / P₀ = 0.294 using 30% nitrogen in helium as absorbed gas. The ASTM procedure was modified as follows: A mixture of 30% nitrogen in helium gas was used; a flow rate of approximately 40 l / min was maintained; The samples were dried in the analysis cells under a stream of nitrogen at 180 ± 5 ° C for one hour and the nitrogen adsorbed by the sample was desorbed by removing the liquid nitrogen dewar and allowing the sample to warm to room temperature without adding heat from outside.

The percent carbon was determined by CHN analysis using a Carlo Erba model 1106 elemental analyzer. A 1-2 mg sample in a sealed tin capsule was burned in an oxygen enriched atmosphere at 1040 ° C on helium support, quantitatively burned over Cr₂OR₃, then the flue gases were passed over Cu at 650 ° C to remove excess oxygen and reduce nitrogen oxides to nitrogen. The gases were then passed through a chromatograph column, separated, and eluted as N₂, CO₂ and H₂O. Gases

ES 2 328 664 T3 eluates were measured with a thermal conductivity detector. The instrument was calibrated by combustion of standard compounds. The results are given in Table 3.

The percentage of mercapto (SH) given in Table 3 was determined by accurately weighing 2-3 g of the treated silica to 0.001 g in an Erlenmeyer flask, adding 75 ml of isopropyl alcohol, purging with nitrogen, sealing with a wet stopper and stirring magnetically for 30 min. The stirred solution was rapidly titrated with 0.1 N standard iodine solution, commercially available from LabChem Inc., to a slightly yellow end point. A blank titration was also done following the same procedure, except that the treated silica was not added. If blocked mercaptosilane had been used to modify the charge, it was necessary to unblock the blocked mercaptosilane before titration. The following equation was used to obtain the final value:

% of SH = (V1-V2) x N x 3.3 / W in the:

V_i is the volume of the iodine solution used with the sample,

V2 is the volume of iodine solution used in the blank test,

N is the normality of the iodine solution,

W is the weight of the silica in grams.

The Silane Conversion Index, expressed as ICS, was determined by NMR ²⁹Yes. This data was obtained on a Bruker AM-100 NMR instrument with a narrow hole magnet and a standard speed 7mm EMA Doty sample. The samples were packed in 7 mm zirconia rotors and sealed with Ke1-F caps. The rotors rotated at the Magic Angle at a speed of approximately 5.0 kHz. Cross-polarization data was obtained using pulses ofⁱH at 90 °, 5600-8400 sweeps per spectrum, a contact time of 5 msec, high-energy proton decoupling during data acquisition, and a relaxation delay time of 3 seconds. Hartmann-Hahn conditions were achieved using a kaolinite sample (J. Rocha and J. Klinowski, J. Magn. Reson. 90, 567 (1990)). All chemical shifts were externally referred to tetramethylsilane (TMS).

All spectra were analyzed using a non-linear curve fitting program (LINESIM) on an Aspect 3000 computer to determine the relative percentage of area for the T peaks.ⁱ (-49 ppm), T² (-57 ppm) and T³ (-65 ppm). The relative percentages of the area by fitting the curve along the region of -30 ppm to -80 ppm.

The pH determination was made on the treated silicas of the Examples and Comparative Examples by the following procedure: 5.0 g of silica (in powder form) are added to a 150 ml flask containing a magnetic stirrer bar; Add 50 ml of isopropanol and 50 ml of deionized water and stir vigorously with splashing until the silica is suspended. A calibrated pH electrode is placed in the solution under vigorous stirring and the pH reading is recorded after 1 minute (± 5 s). The results are given in Table 3.

The Standard Strengthening Index given in Table 3 was determined by dividing the tensile strength at 300% elongation by the tensile strength at 100% elongation. The tensile strength values ​​at 100% and 300% elongation are included in Table 4.

The percentage of Soxhlet extractable carbon from the treated silicas of Examples 1, 2 and 7 was determined by adding approximately 5 grams of each material to 43 mm x 123 mm (inside diameter x outside length) cellulose extraction cylinders, each placed into an appropriately sized Soxhlet collection tube equipped with a condenser. This Soxhlet extraction and condensation system was coupled to a round bottom flask containing 700 ml of toluene. The flask was heated to the reflux temperature of toluene. After holding at reflux for at least 19 hours (typically 19 to 26 hours), the used toluene was replaced with unused toluene and reflux was continued for a minimum of 19 hours (typically 19 to 24 hours). The resulting extractable treated silicas were recovered and dried until a sample had a weight loss of less than 1.2% by weight when exposed to 160 ° C for 10 minutes. The percent carbon of each extracted sample was determined using the procedure described earlier herein. The percentage of Soxhlet extractable carbon was determined using the following equation:

(% carbon before extraction) - (% carbon after extraction) ------------------------------- -------------------------------------------- x 100% carbon before of extraction

The results are presented in Table 5.

ES 2 328 664 T3

TABLE 1

<td>Untreated Silica Used in the Examples</td><td>Specific surface</td>

<td>1-7 and EC1-3</td><td> 191</td>

<td>8y9</td><td> 193</td>

<td> 10</td><td> 172</td>

<td> 11</td><td> 187</td>

<td> 12</td><td> 182</td>

<td> 13</td><td> 214</td>

<td> 14</td><td> 188</td>

<td>EC4 and 5</td><td> 199</td>

TABLE 2

<td>Example no.</td><td>% of MPTMS / SiO₂</td><td>% of DMDCS / SiO₂</td><td>MPTMS / DMDCS</td>

<td> 1</td><td> 2,5</td><td> 15,0</td><td> 0,17:1</td>

<td> 2</td><td> 2,5</td><td> 27,1</td><td> 0,09:1</td>

<td> 3</td><td> 1,0</td><td> 22,0</td><td> 0,05:1</td>

<td> 4</td><td> 5,0</td><td> 15,0</td><td> 0,33:1</td>

<td> 5</td><td> 2,5</td><td> 15,0</td><td> 0.17:1</td>

<td> 6</td><td> 4,0</td><td> 22,2</td><td> 0,18:1</td>

<td> 7</td><td> 2,5</td><td> 15,0</td><td> 0,17:1</td>

<td> 8</td><td> 5,2</td><td> 15,3</td><td> 0,34:1</td>

<td> 9</td><td> 2,6</td><td> 15,3</td><td> 0,17:1</td>

<td> 10</td><td> 4,0</td><td> 22,2</td><td> 0,18:1</td>

<td> 11</td><td> 4,0</td><td> 10,0</td><td> 0,40:1</td>

<td> 12</td><td> 6,0</td><td> 15,0</td><td> 0,40:1</td>

<td> 13</td><td> 4,0</td><td> 22,2</td><td> 0,18:1</td>

<td> 14</td><td> 4,0</td><td> 20,0</td><td> 0,20:1</td>

<td>EC1</td><td> 0,0</td><td> 15,0</td><td> 0:15</td>

<td>EC2</td><td> 1,0</td><td> 12,0</td><td> 0,08:1</td>

<td>EC3</td><td> 0.5</td><td> 15,0</td><td> 0,03:1</td>

<td>EC4</td><td> 4,0</td><td> 0,0</td><td> 4,0:1</td>

<td>EC5</td><td> 0</td><td> 22,0</td><td> 0:22</td>

<td>Ciptane® 1¹²</td><td> 3,0</td><td> 0,0</td><td> 3:0</td>

(12) A precipitated silica indicated to be precoated with 3% by weight of gamma-mercaptopropyltrimethoxysilane and available from PPG Industries, Inc.

ES 2 328 664 T3

TABLE 3

<td>Example no.</td><td>Specific surface, m²/ g</td><td>Carbon,% by weight</td><td>SH, % in weigh</td><td>ICS **</td><td>I WILL GO***</td><td>PH</td>

<td> 1</td><td> 132</td><td> 2,2</td><td> 0,32</td><td> 0,55</td><td> 4,8</td><td> 6,0</td>

<td> 2</td><td> 112</td><td> 3,1</td><td> 0,30</td><td> 0,56</td><td> 4,5</td><td> 6,7</td>

<td> 3</td><td> 119</td><td> 2,5</td><td> 0,16</td><td> 0,62</td><td> 4,2</td><td> 6,8</td>

<td> 4</td><td> 128</td><td> 2,3</td><td>NA *</td><td> 0,56</td><td> 4,9</td><td> 7,3</td>

<td> 5</td><td> 128</td><td> 2,0</td><td> 0,30</td><td> 0,51</td><td> 4,6</td><td> 6,5</td>

<td> 6</td><td> 113</td><td> 3,0</td><td> 0,65</td><td>NA *</td><td> 5,3</td><td> 6,6</td>

<td> 7</td><td> 126</td><td> 2,2</td><td> 0,43</td><td> 0,52</td><td> 4,3</td><td> 7,1</td>

<td> 8</td><td> 103</td><td> 2,8</td><td> 0,63</td><td>NA *</td><td> 5,1</td><td> 8,8</td>

<td> 9</td><td> 108</td><td> 2,7</td><td>NA *</td><td>NA *</td><td> 5,1</td><td> 10,1</td>

<td> 10</td><td> 118</td><td> 3,3</td><td> 0,38</td><td>NA *</td><td> 4,6</td><td> 6,9</td>

<td> 11</td><td> 146</td><td> 2,0</td><td> 0,53</td><td>NA *</td><td> 4,3</td><td> 6,3</td>

<td> 12</td><td> 123</td><td> 3,0</td><td> 0,58</td><td>NA *</td><td> 4,3</td><td> 6,7</td>

<td> 13</td><td> 115</td><td> 3,9</td><td> 0,41</td><td>NA *</td><td> 4,0</td><td> 6,8</td>

<td> 14</td><td> 139</td><td> 1,5</td><td> 0,24</td><td> 0,45</td><td> 4,1</td><td> 6,6</td>

<td>EC 1</td><td> 137</td><td> 1,5</td><td> &lt;0,001</td><td>NA *</td><td> 2,7</td><td> 6,5</td>

<td>EC2</td><td> 149</td><td> 1,4</td><td> 0,12</td><td>NA *</td><td> 3,6</td><td> 6,1</td>

<td>EC3</td><td> 139</td><td> 1,6</td><td> 0,1</td><td>NA *</td><td> 3,5</td><td> 5,8</td>

<td>EC4</td><td> 194</td><td> 0,6</td><td> 0,34</td><td>ND +</td><td> 2,9</td><td> 6,7</td>

<td>EC5</td><td> 134</td><td> 2,6</td><td> &lt;0,001</td><td>NA *</td><td> 2,6</td><td> 6,8</td>

<td>Ciptane®!¹²</td><td> 132</td><td> 0,5</td><td> 0,4</td><td> 0,27</td><td> 3,2</td><td> 7,0</td>

ND * indicates that the test was not performed

ICS ** represents the Silane Conversion index IRE *** represents the Standard Reinforcement index

ES 2 328 664 T3

TABLE 4

<td>Example no.</td><td>Tensile strength to modulus of 300%</td><td>Tensile strength to modulus of 100%</td>

<td> 1</td><td> 8,9</td><td> 1,8</td>

<td> 2</td><td> 8,2</td><td> 1,8</td>

<td> 3</td><td> 7,0</td><td> 1,7</td>

<td> 4</td><td> 10,8</td><td> 2,2</td>

<td> 5</td><td> 8,7</td><td> 1,9</td>

<td> 6</td><td> 12,0</td><td> 2,3</td>

<td> 7</td><td> 7,8</td><td> 1,8</td>

<td> 8</td><td> 11,1</td><td> 2,2</td>

<td> 9</td><td> 9,9</td><td> 1,9</td>

<td> 10</td><td> 9,3</td><td> 2,0</td>

<td> 11</td><td> 8,0</td><td> 1,9</td>

<td> 12</td><td> 10,2</td><td> 2,4</td>

<td> 13</td><td> 6,2</td><td> 1,6</td>

<td> 14</td><td> 7,4</td><td> 1,8</td>

<td>EC1</td><td> 2,8</td><td> 1,0</td>

<td>EC2</td><td> 6,1</td><td> 1,7</td>

<td>EC3</td><td> 5,5</td><td> 1,6</td>

<td>EC4</td><td> 5,5</td><td> 1,9</td>

<td>EC5</td><td> 3,8</td><td> 1,5</td>

<td>Ciptane®1</td><td> 4,8</td><td> 1,5</td>

TABLE 5

<td>Example no.</td><td>% carbon before</td><td>% carbon after</td><td>% of carbon extracted</td>

<td> 1</td><td> 2,18</td><td> 1,81</td><td> 16,97</td>

<td> 2</td><td> 3,11</td><td> 2,54</td><td> 18,33</td>

<td> 7</td><td> 2,20</td><td> 2,16</td><td> 1,82</td>

ES 2 328 664 T3

The results in Table 1 reveal that the specific surfaces of the untreated silica samples used in the procedure to make the Examples and Comparative Examples ranged from 172 to 214 m²/ g.

The MPTMS / DMDCS ratios given in Table 2 for Examples 1-14 ranged from 0.05: 1 to 0.40: 1. This ratio for Comparative Examples 2 and 3, which contained both silanes, was 0.08: 1 and 0.03: 1, respectively. Although the MPTMS / DMDCS ratio of Comparative Example 2 (EC2) was within the desired range of 0.05: 1 to 10: 1, the results for the weight percent mercapto (SH), given in Table 3 for silica EC2 treated, were less than the required amount of more than 0.15% by weight.

The results in Table 3 reveal that the modified silica samples of the present invention, that is, Examples 1-14, had a Standard Reinforcement index of at least 4.0, a weight percent carbon greater than 1, 0, a mercapto weight percent greater than 0.15 and a Silane Conversion Index, that is, T³/ (T¹+ T²+ T³), of at least 0.3. Comparative Examples had less carbon weight percent and / or mercapto weight percent than Examples 1-14 and had a Standard Reinforcement Index of less than 4.0, eg, 3.6.

The results in Table 4 indicated that all of the modified silica of the present invention, ie, Examples 1-14, exhibited a tensile strength for 300% elongation of 6.2 or greater. The tensile strength at 300% elongation of the Comparative Examples was 6.1 or less.

The results in Table 5 reveal that the percentage of Soxhlet extractable carbon ranged from a low value of 1.82% for Example 7 to a high value of 18.33% for Example 2.

Although the present invention has been described with references to specific details of some of its embodiments, such details should not be construed as limitations on the scope of the invention except as included in the claims.