DE10330118A1 - Highly disperse precipitated silica having high CTAB surface area, useful e.g. as filler in tires for commercial vehicles, motor cycles and high speed vehicles, and as antiblocking agents, and carriers for agrochemicals and foodstuffs - Google Patents

Abstract

Precipitated silica (I) has the following characteristics: BET surface area of 200-300 m2/g; CTAB surface area at least 170 m2/g; DBP-number 200-300 g/(100 g); Sears number V2 23-35 ml/(5 g). Independent claims are also included for the following: (1) preparation of (I); (2) elastomeric mixtures, vulcanized rubber mixtures and/or vulcanizates containing (I) as above; (3) tires, tires for commercial vehicles, tires for motor cycles, tires for high speed commercial vehicles, all containing (I) as above.

Description

The present invention relates to a highly disperse precipitated silica, which has a high surface area, a process for their manufacture and their use as a tire filler for commercial vehicles, motorcycles and high speed vehicles.

The use of precipitated silicas in Elastomer compounds such as tires have long been known. Of silicas that When used in tires, high demands are made. They should be light and easily dispersible in the rubber, one good connection with the polymer chains or other fillers contained in the rubber enter and a high, soot-like Have abrasion resistance. In addition to the dispersibility of the silica therefore u. a. the specific surfaces (BET or CTAB) and the oil absorption capacity (DBP) important. The surface properties of silicas determine significantly their possible Application, or certain applications of a silica (e.g. B. Carrier systems or fillers for elastomer mixtures) require certain surface properties.

So revealed US 6013234 the production of precipitated silica with a BET and CTAB surface area of 100 to 350 m ² / g each. This silica is particularly suitable for incorporation into elastomer mixtures, the BET / CTAB ratios being between 1 and 1.5. In EP 0937755 Various precipitated silicas are disclosed which have a BET surface area of approximately 180 to approximately 430 m ² / g and a CTAB surface area of approximately 160 to 340 m ² / g. These silicas are particularly suitable as a carrier material and have a BET to CTAB ratio of 1.1 to 1.3. EP 0647591 discloses a precipitated silica which has a ratio of BET to CTAB surface area of 0.8 to 1.1, which surface characteristics can assume absolute values of up to 350 m ² / g. In EP 0643015 a precipitated silica, which can be used as an abrasive and / or thickening component in toothpastes, is presented, which has a BET surface area of 10 to 130 m2 / g and a CTAB surface area of 10 to 70 m ² / g, ie a BET to CTAB ratio of approx. 1 to 5.21.

Silicas, which are particularly suitable as a filler for elastomer mixtures, here in particular car tires, are described in EP 0901986 with the following properties:
BET surface area 120-300 m ² / g
CTAB surface 100-300 m ² / g
Ratio BET / CTAB 0.8 - 1.3
Sears number V ₂ (consumption 0.1 N NaOH) 6 - 25 ml / (5 g)
DBP number 150 - 300 g / (100 g)
WK coefficient <3.4
Particle size of the degraded particles <1.0 μm
Particle size of the undegraded particles 1.0–100 μm

Vehicle tires have very different requirements depending on the application. In the case of a rough division into car and truck tires, at least the following differences should be noted:

Cars in the sense of the present invention are vehicles for the transportation of people to predominantly private use, d. H. no commercial vehicles such as B. Delivery vehicles. This does not include vehicles that are usually used at high speeds are operated, even if they are considered to be a car due to their design could. These vehicles also have different requirements for tires than the car tires listed in the table.

Tires for motorcycles and high-speed cars have to withstand very high loads at high speeds and have a very good dry and wet slip behavior (traction). However, good traction should not be accompanied by increased abrasion or high rolling resistance.

The different requirements of the vehicles on the tires have corresponding effects the fillers used in the tires. The admixture of silicas and long established in car tires Organosilicon compounds as a filler system leads to reduced rolling resistance, improved traction behavior and less abrasion. A transfer of these improved Properties on tires for Would be commercial vehicles like trucks desirable, because with reduced rolling resistance, lower fuel consumption connected is. The different requirements of the above Lead vehicles to their tires however inevitable on different requirements for the fillers used.

It has been shown that the silicas used in car tires are unsuitable for use in truck tires, motorcycle tires and high-speed tires for cars due to the different profile of requirements. It was therefore an object of the present invention to provide precipitated silicas with a property profile specially tailored to these vehicles. It is known to the person skilled in the art that when active carbon blacks are used as a tire filler, an increase in the surface area results in an improvement in the reinforcement and thus in the abrasion resistance of the tire. However, the use of carbon blacks with high surfaces (CTAB surface> 130 m ² / g) is limited due to the rapidly increasing heat build-up (hysteresis behavior, described and measurable according to DIN 53535, or according to the references mentioned in this DIN) in such filled mixtures.

It has now been found that a precipitated silica that a high CTAB surface has, particularly good as a filler in elastomer mixtures for Commercial vehicle tires, for Motorcycle tires and tires for High speed car is suitable.

The present invention therefore relates to precipitated silicas with a BET surface area of 200-300 m ² / g, a CTAB surface area of 170 170 m ² / g, a DBP number of 200-300 g / (100 g) and one Sears number V ₂ from 23 - 35 ml / (5 g).

Because of the significantly lowered Hysteresis when using silica according to the invention as a filler can also be used surfaces realize that due to soot the higher Forbid hysteresis, thus improving wear resistance to lead.

The precipitated silicas according to the invention can have a maximum CTAB surface area of 300 m ² / g, in particular a CTAB surface area of 170-220 m ² / g or 245-300 m ² / g.

The precipitated silicas according to the invention can each independently have properties in the following preferred ranges:
DBP intake 230 - 300 g / (100 g), in particular 230 - 280 g / (100 g)
WK coefficient ≤ 3.4, preferably ≤ 3.0, especially ≤ 2.5
Sears number V ₂ 26 - 35 ml / (5 g).

The WK coefficient is defined as the ratio of the peak height of the particles that cannot be broken down by ultrasound in the size range 1.0 - 100 μm to the peak height of the broken down particles in the size range <1.0 μm (see 1 ).

EP 1186629 discloses silicas with high CTAB surfaces, which are suitable as fillers for tires. Information about the Sears number and thus about the concentration of hydroxyl groups on the silica surface are EP 1186629 not to be removed.

• a) eine wässrige Lösung eines organischen und/oder anorganischen Salzes und/oder eines Alkali- oder Erdalkalisilikats und/oder einer organischen und/oder anorganischen Base mit einem pH ≥ 9 vorgelegt
• b) in diese Vorlage unter Rühren bei 55 – 95 °C für 10 – 120, bevorzugt 10 – 60 Minuten gleichzeitig Wasserglas und ein Säuerungsmittel dosiert,
• e) mit Schwefelsäure auf einen pH-Wert von ca. 3.5 angesäuert und
• f) filtriert und getrocknet wird.

Another object of the present invention is a method for producing a precipitated silica with a
BET surface area 200-300 m ² / g
CTAB surface area ≥ 170 m ² / g
DBP number 200 - 300 g / (100 g)
Sears number V ₂ 23 - 35 ml / (5 g)
in which

• a) submitted an aqueous solution of an organic and / or inorganic salt and / or an alkali or alkaline earth silicate and / or an organic and / or inorganic base with a pH ≥ 9
• b) waterglass and an acidifying agent are metered into this template while stirring at 55-95 ° C. for 10-120, preferably 10-60 minutes,
• e) acidified with sulfuric acid to a pH of approx. 3.5 and
• f) is filtered and dried.

The precipitated silica produced according to the invention can Have properties in the preferred ranges mentioned.

The template can be approx. 20, 30, 40, 50, 60, 70, 80 or 90% of the final volume of the precipitation. It is possible to get one Use template with little or no electrolyte (salt) and the electrolytes continuously or batchwise (preferably on Beginning of precipitation) admit.

• c) Stoppen der Zudosierung für 30 – 90 Minuten unter Einhaltung der Temperatur und
• d) gleichzeitiges Zudosieren von Wasserglas und Schwefelsäure bei gleicher Temperatur unter Rühren für 20 – 120, bevorzugt 20 – 80 Minuten

durchgeführt.The method according to the invention can optionally have a breakpoint. Here are the steps between steps b) and e)

• c) stopping the metering for 30-90 minutes while maintaining the temperature and
• d) simultaneous metering of water glass and sulfuric acid at the same temperature with stirring for 20-120, preferably 20-80 minutes

carried out.

Optionally, an additional Addition of organic or inorganic salts also during the Steps b) and d) take place. This can be in solution or as a solid, respectively continuously over the addition time of water glass and sulfuric acid or carried out as a batch addition become. It is also possible, dissolve the salts in one or both components and then simultaneously with to admit this.

Alkali or alkaline earth metal salts are preferably used as inorganic salts. In particular, combinations of the following ions can be used:
Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , Be ²⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , H ⁺ , F ^- , Cl ^- , Br ^- , I ^- , SO ₃ ^{2 -} , SO ₄ ^2– , HSO ₄ ^- , PO ₃ ^3– , PO ₄ ^3– , NO ₃ ^- , NO ₂ ^- , CO ₃ ^2– , HCO ₃ ^- , OH ^- , TiO ₃ ^2– , ZrO ₃ ^2– , ZrO ₄ ^4– , AlO ₂ ^- , Al ₂ O ₄ ^2– , BO ₄ ^3– .

The salts of formic, acetic and propionic acid are suitable as organic salts. The alkali or alkaline earth ions mentioned may be mentioned as the cation. The concentration of these salts in the initial charge can be 0.01 to 5 mol / l. Na ₂ SO ₄ is preferably used as the inorganic salt. It is possible to add the acidulant in steps b) and d) in the same or different way, ie with the same or different concentrations and / or feed rates.

Similarly, the water glass in steps b) and d) in the same or different manner Reaction fed become.

In a particular embodiment, the components acidifier and water glass are added in steps b) and d) in such a way that the feed rates in step d) are 125-140% of the feed rates in step b), the components in both steps in equimolar con concentration can be used. The components are preferably added at the same concentration and feed rate.

In addition to water glass (sodium silicate solution), other silicates such as potassium or calcium silicate can also be used. In addition to sulfuric acid, other acidifying agents such as HCl, HNO ₃ , HP ₃ O ₄ or CO ₂ can also be used as acidifying agents.

The filtration and drying of the silicas according to the invention familiar to the expert and can z. B. can be read in the documents mentioned. Prefers the precipitated silica in one Electricity dryer, spray dryer, Floor dryer, belt dryer, rotary tube dryer, flash dryer, Spin flash dryer or nozzle tower dried. These drying options close the operation with an atomizer, a one or two-substance nozzle or an integrated fluid bed on. The precipitated silica according to the invention preferably detects the drying step a particle shape with an average diameter from above 15 μm, especially over 80 μm, especially preferably over 200 μm. The mean particle diameter is defined so that 50% by weight the particle a larger or have a smaller diameter.

After drying, one can Granulation can be carried out with a roller compactor. Here is the average particle diameter at ≥ 1 mm.

The silica according to the invention is preferred in tires for commercial vehicles Used trucks, high speed cars and motorcycles.

As commercial vehicles in the sense of the present Invention apply to all vehicles whose tires have high demands regarding of mileage or wear and tear. Regarding Tires are particularly important for high mileage for buses, To name trucks and / or delivery vehicles and trailers. Regarding Wear resistance such as B. stud tear resistance, chipping, chunking are tires for off-road vehicles, Construction and agricultural machinery, mine vehicles and tractors. Here in particular are vehicles with an axle load of more than 1 ton or with a permissible Total weight over 2, 4, 7.5 or 15 tons. The silicas according to the invention can in particular in traction tires for heavy trucks or their trailers be used. Such vehicles often have axle loads of over 5 tons or a tire diameter of over 17 ''.

Tires for commercial vehicles such as trucks divided into speed classes. The silicas according to the invention are particularly suitable for (Truck) tires for Speeds between 80 and 140 km / h are permitted and the Wear symbols F, G, J, K, L, M or N.

Tires for high speed vehicles (Motorcycle or car) are those designed for speeds over 180 km / h are permitted. These are (car) tires with the symbols S, T, U, H, V, W, Y and ZR.

Another object of the invention are elastomer mixtures, vulcanisable rubber mixtures and / or other vulcanizates which contain the silica according to the invention, such as moldings like pneumatic tires, tire treads, Cable sheaths, hoses, Driving belts, conveyor belts, roller coverings, tires, Shoe soles, sealing rings and damping elements.

Furthermore, the silicas according to the invention can be in be used in all areas of application in which usually silicas are used, such as. B. in battery separators, as anti-blocking agents, as a matting agent in paints and varnishes, as a carrier of Agricultural products and food, in coatings, in printing inks, in fire extinguishing powder, in plastics, in the area of non impact printing, in paper pulp, in the area of personal care and special applications.

• – Druckfarben zur Verdickung oder zum Verhindern von Spritzen und Abliegen,
• – Papier als Füllstoff, Streichpigment, Lichtpauspapier, Thermopapier, bei der Thermosublimation zur Verhinderung des Durchschlagens von Druckfarben, zur Verbesserung der Bildgrundruhe und Kontrast, zur Verbesserung der Punktschärfe und der Farbbrillianz zu verstehen.
• – Unter Verwendung im Bereich personal care ist die Verwendung der erfindungsgemäßen Kieselsäuren als Füllstoff oder Verdickungsmittel z. B. im Bereich der Pharmazie oder Körperpflege zu verstehen.

Using in the area of non impact printing e.g. B. in the inkjet process is the use of the silicas according to the invention in

• - printing inks for thickening or to prevent splashing and dropping,
• - To understand paper as a filler, coating pigment, blueprint paper, thermal paper, in thermal sublimation to prevent the penetration of printing inks, to improve the basic image smoothness and contrast, to improve the sharpness and color brilliance.
• - When used in the personal care area, the use of the silicas according to the invention as a filler or thickener is, for. B. to understand in the field of pharmacy or personal care.

The silica according to the invention can optionally be modified with silanes or organosilanes of the formulas I to III [SiR ¹ _n (RO) _r (Alk) _m , (Ar) _p ] _q [B] (I) . SiR ¹ _n (RO) _3-n (alkyl) (II) , or SiR ¹ _n (RO) _3-n (alkenyl) (III) in which mean
B: -SCN, -SH, -Cl, -NH ₂ , -OC (O) CHCH ₂ , -OC (O) C (CH ₃ ) CH ₂ (if q = 1) or -S _w - (if q = 2), where B is chemically bound to alk,
R and R ¹ : aliphatic, olefinic, aromatic or arylaromatic radical having 2 to 30 carbon atoms, which may optionally be substituted by the following groups: hydroxy, amino, alcoholate, cyanide, thiocyanide, halogen, sulfonic acid -, Sulfonic acid ester, thiol, benzoic acid, benzoic acid ester, carboxylic acid, carboxylic acid ester, acrylate, methacrylate, organosilane radical, where R and R ^{1 can} have the same or different meaning or substitution.
n: 0, 1 or 2,
Alk: a divalent unbranched or branched hydrocarbon radical with 1 to 6 carbon atoms,
m: 0 or 1,
Ar: an aryl radical having 6 to 12 carbon atoms, preferably 6 carbon atoms, which can be substituted by the following groups: hydroxyl, amino, alcoholate, cyanide, thiocyanide-halogen, sulfonic acid, sulfonic acid ester, Thiol, benzoic acid, benzoic acid ester, carboxylic acid, carboxylic acid ester, organosilane residue,
p: 0 or 1, with the proviso that p and n do not simultaneously mean 0,
q: 1 or 2,
w: a number from 2 to 8,
r: 1, 2 or 3, with the proviso that r + n + m + p = 4,
Alkyl: a monovalent unbranched or branched saturated hydrocarbon radical having 1 to 20 carbon atoms, preferably 2 to 8 carbon atoms,
Alkenyl: a monovalent unbranched or branched unsaturated hydrocarbon radical having 2 to 20 carbon atoms, preferably 2 to 8 carbon atoms.

The silica according to the invention can also be used with organosilicon compounds of the composition SiR ² _4-n X _n (with n = 1, 2, 3), [SiR ² _x X _y O] _z (with 0 x x 2 2; 0 y y 2 2 ; 3 ≤ z ≤ 10, with x + y = 2), [SiR ² _x X _y N] _z (with 0 ≤ x ≤ 2; 0 ≤ y ≤ 2; 3 ≤ z ≤ 10, with x + y = 2 ), SiR ² _n X _m OSiR ² _o X _p (with 0 ≤ n ≤ 3; 0 ≤ m ≤ 3; 0 ≤ o ≤ 3; 0 ≤ p ≤ 3, with n + m = 3, o + p = 3 ), SiR ² _n X _m NSiR ² _o X _p (with 0 ≤ n ≤ 3; 0 ≤ m ≤ 3; 0 ≤ o ≤ 3; 0 ≤ p ≤ 3, with n + m = 3, o + p = 3 ), SiR ² _n X _m [SiR ² _x X _y O] _z SiR ² _o X _p (with 0 ≤ n ≤ 3; 0 ≤ m ≤ 3; 0 ≤ x ≤ 2; 0 ≤ y ≤ 2; 0 V o ≤ 3; 0 ≤ p ≤ 3; 1 ≤ z ≤ 10000, with n + m = 3, x + y = 2, o + p = 3). These compounds can be linear, cyclic and branched silane, silazane and siloxane compounds. R ² can be alkyl and / or aryl radicals having 1 to 20 carbon atoms, which can be substituted with functional groups such as the hydroxyl group, the amino group, polyethers such as ethylene oxide and / or propylene oxide and halide groups such as fluoride. R ² can also contain groups such as alkoxy, alkenyl, alkynyl and aryl groups and sulfur-containing groups. X can be reactive groups such as silanol, amino, thiol, halide, alkoxy, alkenyl and hydride groups.

Linear polysiloxanes with the composition SiR ² _n X _m [SiR ² _x X _y O] _z SiR ² _o X _p (with 0 ≤ n ≤ 3; 0 ≤ m ≤ 3; 0 ≤ x ≤ 2; 0 ≤ y ≤ 2 ; 0 ≤ o ≤ 3; 0 ≤ p ≤ 3; 1 ≤ z ≤ 10000, with n + m = 3; x + y = 2; o + p = 3), in which R ^{2 is} preferably represented by methyl.

Polysiloxanes with the composition SiR ² _n X _m [SiR ² _x X _y O] _z SiR ² _o X _P (with 0 ≤ n ≤ 3; 0 ≤ m ≤ 1; 0 ≤ x 2; 0 ≤ y ≤ 2; 0 ≤ o ≤ 3; 0 ≤ p ≤ 1; 1 ≤ z ≤ 1000, with n + m = 3, x + y = 2, o + p = 3), in which R ^{2 is} preferably represented by methyl.

The optionally granulated, ungranulated, ground and / or unmilled precipitated silica can be modified with one or more of the organosilanes mentioned in mixtures of 0.5 to 50 parts, based on 100 parts precipitated silica, in particular 1 to 15 parts, based on 100 parts precipitated silica, where the reaction between precipitated silica and organosilane during the preparation of the mixture (in situ) or outside by spraying and then tempering the mixture, by mixing the organosilane and the silica suspension with subsequent drying and tempering (for example according to DE 3437473 and DE 19609619 ) or according to the procedure described in DE 19609619 or DE-PS 4004781 can be performed.

Suitable as organosilicon compounds yourself basically all bifunctional silanes, on the one hand a coupling to the filler containing silanol groups and on the other hand can achieve coupling to the polymer. Usual used Amounts of the organosilicon compounds are based on 1 to 10% by weight, on the total amount of precipitated silica.

Examples of these organosilicon compounds are: bis (3-triethoxysilylpropyl) tetrasulfan, bis (3-triethoxysilylpropyl) disulfan, vinyltrimethoxysilane, vinyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilanim, 3-mercaptopropyltriethoxysilanil, 3 Further organosilicon compounds are described in WO 99/09036, EP 1108231 , DE 10137809, DE 10163945, DE 10223658.

In a preferred embodiment In the invention, the bis (triethoxysilylpropyl) tetrasulfane can be used as the silane be used.

The silica according to the invention can be used in elastomer mixtures, Tires or vulcanizable rubber compounds as reinforcing fillers in amounts of 5 to 200 parts, based on 100 parts of rubber as Powder, spherical Product or granulate both with and without silane modification Silane modification can be mixed.

Rubber and elastomer mixtures are to be regarded as equivalent in the sense of the present invention.

In addition to mixtures that only the silicas according to the invention, with and without the mentioned organosilanes, as fillers, can Elastomer or rubber mixtures additionally with one or more more or less reinforcing fillers filled his.

• – Ruße: Die hierbei zu verwendenden Ruße sind nach dem Flammruß-, Furnace- oder Gasruß-Verfahren hergestellt und besitzen BET-Oberflächen von 20 bis 200 m²/g, wie z. B. SAF-, ISAF-, HSAF-, HAF-, FEF- oder GPF-Ruße. Die Ruße können gegebenenfalls auch Heteroatome wie zum Beispiel Silizium enthalten.
• – hochdisperse pyrogene Kieselsäuren, hergestellt zum Beispiel durch Flammenhydrolyse von Siliziumhalogeniden. Die Kieselsäuren können gegebenenfalls auch als Mischoxide mit anderen Metalloxiden, wie Al-, Mg-, Ca-, Ba-, Zn- und Titanoxiden vorliegen.
• – weitere kommerzielle Kieselsäuren
• – Synthetische Silicate, wie Aluminiumsilicat, Erdalkalisilicate wie Magnesiumsilicat oder Calcitunsilicat, mit BET-Oberflächen von 20 bis 400 m²/g und Primärteilchendurchmessern von 10 bis 400 nm
• – Synthetische oder natürliche Aluminiumoxide und -hydroxide
• – Natürliche Silicate, wie Kaolin andere natürlich vorkommende Siliziumdioxidverbindungen
• – Glasfaser und Glasfaserprodukte (Matten, Stränge) oder Mikroglaskugeln
• – Stärke und modifizierte Stärketypen
• – Naturfüllstoffe, wie zum Beispiel Clays und Kieselkreide

The following materials can be used as additional fillers:

• - Carbon blacks: The carbon blacks to be used here are produced by the flame black, furnace or gas black process and have BET surface areas of 20 to 200 m ² / g, such as. B. SAF, ISAF, HSAF, HAF, FEF or GPF carbon blacks. The carbon blacks can optionally also contain heteroatoms such as silicon.
• - highly disperse fumed silicas, produced for example by flame hydrolysis of silicon halides. The silicas can optionally also be present as mixed oxides with other metal oxides, such as Al, Mg, Ca, Ba, Zn and titanium oxides.
• - other commercial silicas
• - Synthetic silicates, such as aluminum silicate, alkaline earth metal silicates, such as magnesium silicate or calcite silicate, with BET surface areas of 20 to 400 m ² / g and primary particle diameters of 10 to 400 nm
• - Synthetic or natural aluminum oxides and hydroxides
• - Natural silicates, such as kaolin, other naturally occurring silicon dioxide compounds
• - Glass fiber and glass fiber products (mats, strands) or micro glass balls
• - Starch and modified starch types
• - Natural fillers such as clays and pebbles

The blend ratio judges here, as with the dosing of the organosilanes, after the property profile of the finished rubber mixture to be achieved. On relationship from 5 - 95 % between the silicas according to the invention and the other fillers mentioned above (also as a mixture) is conceivable and is also realized in this context.

In a particularly preferred embodiment can 10 to 150 parts by weight of silica, wholly or partly consisting of the silica according to the invention, if appropriate together with 0 to 100 parts by weight of carbon black, and 1 to 10 parts by weight an organosilicon compound, based in each case on 100 parts by weight Rubber, can be used to produce the mixtures.

In addition to the silicas of the invention, the Organosilanes and other fillers the elastomers form another important component of the rubber mixture. To be mentioned here elastomers, natural and synthetic, oil-stretched or not, as a single polymer or blend with other rubbers, such as natural rubbers, polybutadiene (BR), polyisoprene (IR), styrene / butadiene copolymers with styrene contents from 1 to 60, preferably 2 to 50 wt .-% (SBR) in particular produced by means of the solution polymerization process, Butyl rubbers, isobutylene / isoprene copolymers (IIR), butadiene / acrylonitrile copolymers with acrylonitrile contents of 5 to 60, preferably 10 to 50% by weight (NBR), partially hydrogenated or fully hydrogenated NBR rubber (HNBR), ethylene / propylene / diene copolymers (EPDM), as well as mixtures these rubbers.

Furthermore come for rubber mixtures with the mentioned rubbers the following additional rubbers in question: Carboxyl rubbers, epoxy rubbers, trans-polypentenamers, halogenated butyl rubbers, Rubbers made of 2-chloro-butadiene, ethylene-vinyl acetate copolymers, ethylene-propylene copolymers, if appropriate also chemical derivatives of natural rubber and modified natural rubbers.

Preferred synthetic rubbers are for example at W. Hofmann, "Kautschuktechnologie", Genter Verlag, Stuttgart 1980.

For the manufacture of the tires according to the invention are in particular anionically polymerized L-SBR rubbers (Solution SBR) with a glass transition temperature above –50 ° C and their Mixtures with diene rubbers of interest.

The silicas according to the invention, with or without silane, can Use in all rubber applications, such as moldings, tires, Tire treads, Conveyor belts, Conveyor belts, seals, Driving belts, hoses, Shoe soles, cable jackets, Roll coverings, damping elements etc. find.

The incorporation of this silica and the preparation of the mixtures containing this silica takes place in the usual way in the rubber industry on one Internal mixer or rolling mill at preferably 80-200 ° C. The form of administration or use of silicas can be both powder, spherical Product or granules. Here too, they differ silicas according to the invention not of the well-known light fillers.

The rubber vulcanizates according to the invention can further rubber auxiliaries in the usual Dosages contain, such as reaction accelerators, anti-aging agents, heat stabilizers, light stabilizers, ozone protection agents, processing aids, plasticizers, tackifiers, blowing agents, dyes, pigments, waxes, extenders, organic acids, retarders, metal oxides and activators such as triethanolamine, polyethylene glycol, hexanetriol. These compounds are known in the rubber industry.

The rubber auxiliaries can in Known amounts, which vary according to the purpose judge, be used. usual Quantities are, for example, quantities from 0.1 to 50% by weight, based on Rubber. Can be used as a crosslinker Sulfur or sulfur donors are used. The rubber mixtures according to the invention can about that also contain vulcanization accelerators. Examples of suitable ones The main accelerators are mercaptobenzthiazoles, sulfenamides, thiurams, Dithiocarbamates in amounts of 0.5 to 3% by weight. Examples of co-accelerators are guanidienes, thioureas and thiocarbonates in amounts of 0.5 to 5% by weight. Sulfur can usually in amounts of 0.1 to 10% by weight, preferably 1 to 3% by weight on rubber.

The silicas according to the invention can be used in rubbers be with accelerators and / or sulfur, but also peroxidic can be networked.

The vulcanization of the rubber mixtures according to the invention can optionally at temperatures of 100 to 200 ° C, preferably 130 to 180 ° C under pressure from 10 to 200 bar. Mixing of rubbers with the filler, optionally rubber auxiliaries and the organosilicon compound in known mixing units, such as rollers, internal mixers and mixing extruders, carried out become.

The highly dispersible high-surface area silicas according to the invention have the advantage that they improve the rubber vulcanizates Abrasion resistance due to the higher Apply the CTAB surface. In addition, the dry handling is due to the higher dynamic rigidity at 0 ° C and 60 ° C improved and the rolling resistance, indicated by the reduced tan δ (60 ° C) value, decreased. Analogous to carbon blacks, when using this highly dispersible, high surface area silicas an improved cut & chip, or chunking behavior achieved (for definition and further explanations see "New insights into the tear mechanism "and references therein at Tire Tech 2003 in Hamburg by Dr. W. Niedermeier).

The rubber mixture according to the invention is in particular for the Manufacture of tire treads with improved lower rolling resistance, improved wet skid resistance, improved drying properties and good abrasion resistance compared to a same rubber mixture with previously known silicas. These tread compound are especially for High-speed car and motorcycle tires, but also tires for commercial vehicles with reduced rolling resistance with good abrasion resistance and improved Cut & Chip and Chunking behavior suitable.

The silicas according to the invention are also suitable without the addition of organosilicon compounds, in the blend with a typical Tread soot also Improvement of the cut & chip Behavior of construction, agricultural machinery and mine tires.

To achieve a good picture of values in a polymer mixture is the dispersion of the precipitated silica in the Matrix, the polymer, is vital. This can be done by estimated the WK coefficient become.

1 is a schematic representation of the values necessary for the calculation of the WK coefficient.

The curves show a first in the range around 1.0 - 100 μm Maximum in particle size distribution and another in the range <1.0 μm Maximum. The peak in the 1.0 - 100 μm range indicates the proportion of uncrushed silica particles after the ultrasound treatment. These become quite coarse particles poorly dispersed in the rubber compounds. The second peak with significantly smaller particle sizes (<1.0 μm) gives that part of particles of silica at who during the ultrasound treatment has been crushed. These very small ones Particles are excellently dispersed in rubber compounds.

The WK coefficient is now the ratio of the peak height the non-degradable particles (B), the maximum of which is in the range 1.0-100 μm (B '), to the peak height of the degraded particles (A), the maximum of which is in the range <1.0 μm (A ').

The WK coefficient is therefore one Measure of "degradability" (= Dispersibility) of the precipitated silica. It is a precipitated silica the smaller the WK coefficient, the easier it is to disperse, d. H. the more particles are broken down during incorporation into rubber become.

The silicas according to the invention have WK coefficients 3.4 3.4, preferably 3.0 3.0, particularly preferably ≤ 2.5 on. Known precipitated silicas other WK coefficients and other maxima in the particle size distributions measured with the Coulter LS 230 and are therefore more difficult to disperse.

The physical / chemical data of the precipitated silicas according to the invention determined using the following methods:

Determination of the moisture of silicas

According to ISO 787-2, the volatile components (in the following the Ein called half humidity) of silica after 2 hours of drying at 105 ° C. This drying loss generally consists mainly of water moisture.

execution

In a dry weighing glass with Ground joint cover (diameter 8 cm, height 3 cm) 10 g of the powdery, spherical or granular silica Weighed to the nearest 0.1 mg (sample weight E). The sample is opened Cover 2 h at 105 ± 2 ° C in one Drying cabinet dried. Then the weighing glass is closed and in a desiccator cabinet with silica gel as a drying agent cooled to room temperature. The weight A is determined gravimetrically.

The moisture in% is determined according to ((E in g - A in g) · 100 %) / (E in g).

Determination of the modified Sears number of silicas

The modified Sears number (hereinafter referred to as Sears number V ₂ ) can be determined as a measure of the number of free hydroxyl groups by titration of silica with potassium hydroxide solution in the range from pH 6 to pH 9.

The determination method is based on the following chemical reactions, with "Si" -OH symbolizing a silanol group of silica: "Si" -OH + NaCl → "Si" -ONa + HCl HCl + KOH → KCl + H ₂ O.

execution

10.00 g of a powder, spherical or granular silica with 5 ± 1 % Humidity is 60 seconds with an IKA M 20 universal mill (550 W; 20,000 rpm) crushed. If necessary, the moisture content the starting substance by drying at 105 ° C in a drying cabinet or even moistening set and the crushing can be repeated. 2.50 g the treated silica are weighed into a 250 ml titration vessel at room temperature and with 60.0 ml of methanol p. A. offset. After complete wetting 40.0 ml of deionized water are added to the sample and one dispersed using an Ultra Turrax T 25 stirrer (stirrer shaft KV-18G, 18 mm diameter) For 30 seconds at a speed of 18,000 rpm. With 100 ml Deionized water becomes the sample particles adhering to the rim of the vessel and stirrer rinsed into the suspension and tempered to 25 ° C in a thermostatted water bath.

The pH measuring device (from Knick, type: 766 Calimatic pH meter with temperature sensor) and the pH electrode (combination electrode from Schott, type N7680) are calibrated at room temperature using buffer solutions (pH 7.00 and 9.00). With the pH meter, the initial pH value of the suspension is first measured at 25 ° C, then, depending on the result, the pH value is adjusted with potassium hydroxide solution (0.1 mol / l) or hydrochloric acid solution (0.1 mol / l) 6:00 set. The consumption of KOH or HCl solution in ml up to pH 6.00 corresponds to V ₁ '. Then 20.0 ml of sodium chloride solution (250.00 g of NaCl p.A. made up to 1 liter with deionized water) are added. The titration is then continued with 0.1 mol / l KOH until the pH is 9.00. The consumption of KOH solution in ml up to pH 9.00 corresponds to V ₂ '.

Subsequently, the volumes V ₁ 'or V ₂ ' are first standardized to the theoretical weight of 1 g and expanded by 5, which results in V ₁ and the Sears number V ₂ in the units ml / (5 g).

Determination of the BET surface area

The specific nitrogen surface (in following BET surface called) the powdery, spherical or granular silica is in accordance with ISO 5794-1 / Annex D with an AREA meter (from Ströhlein, JUWE) determined.

Determination of the CTAB surface

The method is based on the adsorption of CTAB (N-hexadecyl-N, N, N-trimethylammonium bromide) on the “outer” surface of the silica, which is also referred to as the “rubber-active surface”, in accordance with ASTM 3765 or NFT 45-007 (Chapter 5.12.1.3). CTAB is adsorbed in aqueous solution with stirring and ultrasound treatment. Excess, non-adsorbed CTAB is removed by Back titration with NDSS (dioctyl sodium sulfosuccinate solution, "Aerosol OT" solution) was determined with a titroprocessor, the end point being given by the maximum turbidity of the solution and being determined with a phototrode. The temperature during all operations carried out was 23-25 ° C to prevent the crystallization of CTAB The back titration is based on the following reaction equation:

equipment

Titroprocessor METTLER Toledo type DL 55 and titroprocessor METTLER Toledo type DL 70, each equipped with: pH electrode, manufactured by Mettler, type DG 111 and phototrode, manufactured by Mettler, type DP 550
Titration beaker 100 ml made of polypropylene
Titration glass vessel, 150 ml with lid
Pressure filtration device, 100 ml content
Membrane filter made of cellulose nitrate, pore size 0.1 μm, 47 mm ⌀, e.g. B. Whatman (Cat. No. 7181-004).

reagents

The solutions from CTAB (0.015 mol / l in deionized, water) and NDSS (0.00423 mol / l in deionized Water) are obtained ready for use (Kraft, Duisburg: order no. 6056.4700 CTAB solution 0.015 minor; Order no. 6057.4700 NDSS solution 0.00423 mol / l), stored at 25 ° C and used up within a month.

execution

Blank titration

The consumption of NDSS solution for Titration of 5 ml CTAB solution is 1 × daily to each series of measurements check. For this purpose, the phototrode is set to 1000 ± 20 mV before the titration begins set (corresponding to a transparency of 100%).

Exactly 5.00 ml of CTAB solution are pipetted into a titration beaker and 50.0 ml of deionized water are added. The titration with NDSS solution is carried out with stirring using the DL 55 titroprocessor up to the max. Turbidity of the solution. The consumption V _I of NDSS solution is determined in ml. Each titration must be carried out as a triple determination.

adsorption

10.0 g of the powdery, spherical or granular silica with a moisture content of 5 ± 2 % (if necessary, the moisture content is obtained by drying at 105 ° C in a drying cabinet or even moistening set) with a grinder (Krups, Model KM 75, Article No. 2030-70) crushed for 30 seconds. Exactly 500.0 mg of the comminuted sample are transferred to a 150 ml titration vessel with magnetic stirrers and there will be exactly 100.0 ml of CTAB solution added. The titration vessel is equipped with a Cover closed and stirred for 15 minutes with a magnetic stirrer. hydrophobic silicas are with an Ultra Turrax T 25 stirrer (agitator shaft KV-18G, 18 mm diameter) at 18,000 rpm for a maximum of 1 minute until fully wetted touched. The titration vessel turns on screwed the DL 70 titroprocessor and the pH of the suspension is adjusted to a value of 9 ± 0.05 with KOH (0.1 mol / l). It takes place a 4 minute Sonication of the suspension in the titration vessel in an ultrasonic bath (Fa. Bandelin, Sonorex RK 106 S, 35 kHz) at 25 ° C. Then there is an immediate one Pressure filtration through a membrane filter at nitrogen pressure from 1.2 bar. The flow of 5 ml is discarded.

titration

5.00 ml of the remaining filtrate are pipetted into a 100 ml titration beaker and made up to 50.00 ml with deionized water. The titration beaker is screwed onto the DL 55 titroprocessor and the titration with NDSS solution is carried out with stirring until the maximum turbidity. The consumption V _II of NDSS solution in ml is determined. Each turbidity is to be carried out as a triple determination.

calculation

With the help of the measured values
V _I = consumption of NDSS solution in ml when titrating the blank sample
V _II = consumption of NDSS solution in ml when using the filtrate
surrendered:
V _I N _II = amount of substance CTAB of the blank / remaining amount of substance CTAB in the filtrate sample.

From this it follows for the adsorbed substance quantity N of CTAB in g: N = ((V _I - V _II ) x 5.5 g x 5 ml) / (V _I x 1000 ml).

Since only 5 ml of 100 ml of filtrate was titrated, 0.5 g of silica with a defined moisture content was used and the space requirement of 1 g of CTAB 578435 · 10 ^-3 m ² follows from this:
CTAB surface (not water-corrected) in m ² / g = (N · 20 · 578.435 m ² /g)/(0.5 g) and
CTAB surface area (not water-corrected) in m ² / g = ((V _I - V _II ) 636.2785 m ² / g) / V _I.

The CTAB surface is on the anhydrous silica related, which is why the following correction is made.

CTAB surface area in m ² / g = (CTAB surface area (not water-corrected) in m ² / g · 100%) / (100% moisture in%).

Determination of the DBP intake

The DBP intake (DBP number) that a measure of absorbency which is precipitated silica, is determined based on the DIN 53601 standard as follows:

execution

12.50 g of powdered or spherical silica with 0-10 % Moisture content (if necessary, the moisture content is determined by drying at 105 ° C set in the drying cabinet) in the kneader chamber (article Number 279061) of the Brabender absorptometer Given "E". In the case of granules, the sieve fraction from 3.15 up to 1 mm (stainless steel sieves from Retsch) are used (by gentle To press the granules with a plastic spatula through the sieve with 3.15 mm pore size). Under constant Mixing (circulation speed of the mixer blades 125 rpm) drips at room temperature with the "Dosimaten Brabender T 90/50" Dibutyl phthalate into the mixture at a rate of 4 ml / min. The mixing takes place with little power and is based on the digital display. Towards the end of the determination it will Mixture pasty, which is indicated by a steep increase in power requirements. With a display of 600 digits (torque of 0.6 Nm) through an electrical contact of both the kneader and the DBP dosage off. The synchronous motor for the DBP supply is with one digital counter coupled so that the consumption of DBP can be read in ml.

evaluation

The DBP intake is in g / (100 g) specified and using the following formula from the measured DBP consumption calculated. The density of DBP is typically 1,047 g / ml at 20 ° C.

DBP intake in g / (100 g) = ((consumption of DBP in ml) · (density of the DBP in g / ml) 100) / (12.5 G).

The DBP intake is for the anhydrous, dried silica Are defined. When using damp precipitated silica correct the value using the following correction table. The correction value corresponding to the water content becomes experimental added certain DBP value; z. B. would have a water content of 5.8 % means a supplement of 33 g / (100 g) for the DBP intake.

Correction table for dibutyl phthalate intake -hydrous-

Determination of the WK coefficient: Aggregate size distribution by means of laser diffraction

sample preparation

Is it the one to be measured? silica around granules, 5 g of the granular silica are placed in a beaker and the coarse-grained granular pieces crushed with a pestle but not mortar. 1.00 g of the crushed, powdery or spherical silica with 5 ± 1 % Moisture content (if necessary, the moisture content is determined by drying at 105 ° C in the drying cabinet or evenly moistened discontinued), which were manufactured a maximum of 10 days ago, is placed in a 30 ml centrifuge glass with a curved bottom (height 7 cm, ⌀ 3 cm, Depth of convex curvature 1 cm) weighed and with 20.0 ml of dispersion solution (hydrophilic silicas: 20.0 g of sodium hexametaphosphate (from Baker) to 1000 ml with deionized Replenished water; Hydrophobic silicas: 200.0 ml ethanol p. A. with 2.0 ml of 25% ammonia solution and 0.50 g Triton X-100 (Merck) to 1000 ml with deionized water filled) added. Subsequently the centrifuge glass is placed in a double-walled glass cooling vessel (80 ml Capacity, height 9 cm, ⌀ 3.4 cm) with cooling water connections for tap water (20 ° C) and the sample 270 s with an ultrasonic finger (from Bandelin, Type UW 2200 treated with horn DH 13 G and diamond plate ⌀ 13 mm). This will on the power supply (Sonopuls, from Bandelin, type HD 2200) of the ultrasonic finger 50% power and 80% pulses (corresponds to 0.8 s power and 0.2 s pause) set. By water cooling will warming the Suspension of maximum 8 ° C guaranteed. Until the sample is added to the liquid module of the laser diffraction device takes place within 15 min, the suspension is stirred with a magnetic stirrer prevent any sedimentation.

execution

Before starting the measurement, let the laser diffraction device LS 230 (from Coulter) and the liquid module (LS Variable Speed Fluid Module Plus with integrated ultrasonic finger CV 181, from Coulter) warm up for 2 hours and rinse the module (menu bar "Control / Flushing") 10 minutes long. In the control bar of the device software, select the "Opt." Calculate model "and defines the refractive indices in an .rfd file as follows: Liquid refractive index BI Real = 1,332; Material refractive index Real = 1.46; Imaginary = 0.1. In the" Measuring cycle "file window, you set the pump speed to 26% and the ultrasound power of the integrated ultrasound finger CV 181 to 3. The ultrasound points "during sample addition", "10 seconds before each measurement" and "during measurement" must be activated. In addition, the following points are selected in this file window: offset measurement, adjustment, background measurement, set measurement concentration, enter sample information, Enter measurement info Start 2 measurements, automatic rinsing, with PIDS data.

After completing the calibration measurement with an LS Size Control G15 standard (from Coulter) and the background measurement, the sample is added. You add so long suspended silica until a light absorption of 45 - 55% is reached and that Device reports "OK".

The measurement is carried out at room temperature with the evaluation model of the .rfd file specified above. Of each silica sample three double determinations of 60 seconds each with one Waiting time of 0 seconds carried out.

The software calculates the particle size distribution from the raw data curve on the basis of the volume distribution taking into account Mie theory and the optical model from Fraunhofer. A bimodal distribution curve is typically found with a mode A between 0 - 1 μm (maximum at approx. 0.2 μm) and a mode B between 1 - 100 μm (maximum at approx. 5 μm). According to the 1 the WK coefficient can be determined from this, which is given as the mean of six individual measurements.

pH Determination

The process based on DIN EN ISO 787-9 is used to determine the pH of an aqueous Silica suspension at 20 ° C. For this, an aqueous Suspension of the sample to be examined is prepared. After a short time shake the suspension becomes its pH determined using a previously calibrated pH meter.

execution

This is before performing the pH measurement pH meter (Knick, type: 766 Calimatic pH meter with temperature sensor) and the pH electrode (single-rod measuring chain from Schott, type N7680) daily Use of the buffer solutions at 20 ° C to calibrate. The calibration function should be selected so that the two buffer solutions used Include the expected pH of the sample (buffer solutions with pH 4.00 and 7.00, pH 7.00 and pH 9.00 and possibly pH 7.00 and 12.00). When using granules, 20.0 g of silica are first used a mill (Krups, model KM 75, article no. 2030-70) crushed for 20 s.

5.00 g of powdered or spherical silica with 5 ± 1 % Moisture content (if necessary, the moisture content is determined by drying at 105 ° C in the drying cabinet or evenly moistened before any shredding) are set on a precision balance Weighed to the nearest 0.01 g in a previously tared glass wide-mouth bottle. 95.0 ml of deionized water are added to the sample. Then will the suspension in the sealed vessel for 5 minutes, using a shaker (Gerhardt, model LS 10, 55 W, level 7) shaken at room temperature. The The pH value is measured immediately after shaking. To is the electrode first with deionized water, followed by part of the suspension rinsed and subsequently immersed in the suspension. After adding a magnetic fish in the suspension becomes lighter at a constant stirring speed Drum formation of the suspension carried out the pH measurement. If If the pH meter shows a constant value, the pH value becomes read on the display.

When using hydrophobic silica the implementation takes place analog, but then 5.00 g of the possibly crushed sample with 5 ± 1 % Moisture content on the precision balance Weighed to the nearest 0.01 g in a previously tared glass wide-mouth bottle. 50.0 ml of methanol p. A. and 50.0 ml of deionized water added and then the suspension is kept in a sealed vessel for 5 minutes a shaker (Gerhardt, model LS 10, 55 W, level 7) shaken at room temperature. The The pH value is also measured with stirring, but after exact 5 min.

Determination of the solids content of filter cake

According to this method the solids content determined by filter cake by removing the volatile components at 105 ° C.

execution

100.00 g of the filter cake are weighed into a dry, tared porcelain bowl (diameter 20 cm) (weight E). If necessary, the filter cake is crushed with a spatula in order to obtain loose chunks of a maximum of 1 cm ³ . The sample is dried to constant weight at 105 ± 2 ° C in a drying cabinet. The sample is then cooled to room temperature in a desiccator cabinet with silica gel as the drying agent. The weight A is determined gravimetrically.

The solids content is determined in% according to 100% - (((E in g - A in g) · 100 %) / (E in g)).

Determination of the electrical conductivity

The determination of electrical conductivity (LF) of silicas becomes watery Suspension carried out.

execution

When using granules first 20.0 g of silica by means of a mill (Krups, model KM 75, article no. 2030-70) crushed for 20 s. 4.00 g powder or spherical Silica with 5 ± 1 % Moisture content (if necessary, the moisture content is determined by drying at 105 ° C in the drying cabinet or evenly moistened adjusted before any crushing) are deionized in 50.0 ml Suspended water and heated to 100 ° C for 1 min. The sample cooled to 20 ° C is made up to exactly 100 ml and by shaking homogenized.

The measuring cell of the LF 530 conductivity meter (Fa. WTW) is rinsed with a small amount of sample before the measuring cell LTA01 is immersed in the suspension. The one shown on the display The value corresponds to the conductivity at 20 ° C, because the external temperature sensor TFK 530 performs automatic temperature compensation. This Temperature coefficient as well as the cell constant k are in front of everyone test series to check.

0.01 mol / l potassium chloride solution is used as the calibration solution (LF at 20 ° C = 1278 μS / cm).

The following examples are intended to Invention closer explain, without limiting its scope.

example 1

41,601 water and 0.02 kg water glass (density 1,348 kg / l, 27.1% SiO ₂ , 8.00% Na ₂ O) and 0.50 kg Na ₂ SO ₄ are placed in a reactor made of stainless steel with a propeller stirring system and double jacket heating.

8.90 l / h of water glass and about 2.10 l / h of sulfuric acid (density 1.40 kg / l, 50.6% H ₂ SO ₄ ) are then metered in with vigorous stirring at 60 ° C. for 55 minutes. This sulfuric acid metering is regulated so that the reaction medium has a pH of 9.0 (measured at room temperature). The addition of water glass is then stopped and the sulfuric acid is continued until a pH of 3.3 (measured at room temperature) is reached.

The suspension obtained is filtered as usual and washed with water. The filter cake with 18% solids content becomes watery sulfuric acid and liquefied a shaving unit. The silica food with 16% solids content is then spray dried.

The powdery product obtained has a BET surface area of 238 m ² / g, a CTAB surface area of 199 m ² / g, a DBP uptake of 288 g / (100 g), a Sears number V ₂ of 23.6 ml / (5 g) and a conductivity of 570 μS.

Example 2

41.61 water and 0.02 kg water glass (density 1,348 kg / l, 27.1% SiO ₂ , 8.00% Na ₂ O) and 0.5 kg Na ₂ SO ₄ are placed in a reactor made of stainless steel with a propeller stirring system and double jacket heating.

8.95 l / h of water glass and about 2.05 l / h of sulfuric acid (density 1.40 kg / l, 50.6% H ₂ SO ₄ ) are then metered in with vigorous stirring at 64 ° C. for 56 minutes. This sulfuric acid metering is regulated so that the reaction medium has a pH of 9.0 (measured at room temperature). The addition of water glass is then stopped and the sulfuric acid is continued until a pH of 3.3 (measured at room temperature) is reached.

The suspension obtained is filtered as usual and washed with water. The filter cake with 18% solids content becomes watery sulfuric acid and liquefied a shaving unit. The silica food with 16% solids content is then spray dried.

The powdery product obtained has a BET surface area of 233 m ² / g, a CTAB surface area of 193 m ² / g, a DBP uptake of 276 g / (100 g), a Sears number V ₂ of 23.2 ml / (5 g) and a conductivity of 420 μS.

Example 3

Examination of the precipitated silicas according to the invention from Examples 1 and 2 in an emulsion SBR rubber mixture. The easily dispersible tread silicic acid Ultrasil 7000 GR and the high surface silicic acid Zeosil 1205 MP were selected as state of the art. Ultrasil 7000 GR is a well dispersible precipitated silica from Degussa AG with a CTAB surface area of 160 ± 10 m2 / g. Zeosil 1205 MP is a high-surface silica from Rhodia with a CTAB surface area of 200 ± 10 m ² / g.

The one used for the rubber compounds The recipe is given in Table 1 below. Here means the unit phr parts by weight, based on 100 parts of the used Raw rubber. Mixtures A and B contain the silicas and the mixtures R1 and R2 serve as references according to the state of the technique. To the dispersion quality to judge the shear forces introduced when mixing as possible be kept constant. This leaves adapted to the CTAB surface Dosage of the silane, but also the crosslink density when changed To keep the amount of silane comparable is a sulfur correction of the sulfur content of the silane is necessary (H.-D. Luginsland, J. Fröhlich, A. Wehmeier, paper No. 59 presented at the ACS meeting, April 24-27, 2001, Providence / Rhode Island, USA).

The general process for the production of rubber mixtures and their vulcanizates is described in the book: "Rubber Technology Handbook", W. Hofmann, Hanser Verlag 1994. Table 1

The polymer Buna 1500 deals it is an emulsion polymerized SBR copolymer from Bayer AG with a styrene content of 23.5% by weight. Si 69 is the coupling reagent bis (3-triethoxysilylpropyl) tetrasulfan Degussa AG. Renopal NS is a mineral oil from Fuchs Mineralölwerke. Vulkanox HS / LG (TMQ), Vulkacit CZ / EG (CBS) and Vulkacit Thiuram / C (TMTD) are commercial products from Bayer AG.

The rubber compounds are in an internal mixer according to the mixing instructions in Table 2 manufactured.

Table 2

Table 3 lists the methods for rubber testing. Table 3

The dispersion coefficient becomes optical certainly. The determination can be made by the German Institute for Rubber Technology e.V., Hanover / Germany. In addition, the procedure described in: H. Geisler, "Determination of the Mixing Quality", presented at the DIK workshop, 27-28. November 1997, Hannover / Germany.

The mixtures are at 15 min 165 ° C vulcanized. Table 4 shows the results of the rubber test.

Table 4

How to look at the data in table 4 recognizes, the mixtures A and B with the silicas according to the invention have a higher Mooney viscosity than the reference mixture R1. This is due to the stronger silica network, due to the higher Silica surface of the silicas according to the invention compared to the Reference silica Ultrasil 7000 GR. Opposite the conventional high surface area silica Zeosil 1205 MP in reference mixture R2, however, the viscosity is advantageous decreased, which implies improved processability. The Vulcanization time is t90% due to the lack of accelerator adjustment in cf. extended to Ultrasil 7000 GR and on the elevated Surface of the attributed silicas according to the invention; as well is the crosslink density measured as the torque difference Dmax-Dmin decreased. Despite the lack of accelerator adaptation, the Tensile strengths, tension values and hardening of the mixtures according to the invention A and B are good reinforcements on. The hardships of mixtures R1, A and B are comparable, while the hardness of mixture R2 is clear is increased. This already shows an insufficient Dispersion of the conventional high-surface silica in R2. The quality of dispersion of mixtures A and B is over 90% very good and reaches the level of highly dispersible silica in R1, while the dispersion in R2 with the high-surface silica the state of the art is significantly worse.

Example 4

Examination of the precipitated silicas according to the invention Examples 1 and 2 in an S-SBR / BR rubber mixture. As The ultrasil 7000 GR and Zeosil silicas were again state of the art 1205 MP selected.

The one used for the rubber compounds Recipe is given in Table 5 below. The reference silica Ultrasil 7000 GR in mixture R3 was modified with 6.4 phr Si 69. To the higher surface area of the reference silica Zeosil 1205 MP and the silicas according to the invention was taken into account in the mixtures R4, C and D the amount of silane increased to 8 phr and the Sulfur amount reduced accordingly. A sulfur correction is necessary according to the sulfur content of the silane (H.-D. Luginsland, J. Happy, A. Wehmeier, paper No. 59 presented at the ACS meeting, April 24-27, 2001, Providence / Rhode Iceland, USA).

Table 5

The polymer is VSL 5025-1 it is a in solution polymerized SBR copolymer from Bayer AG with a styrene content of 25% by weight and a butadiene content of 75% by weight. The copolymer contains 37.5 phr oil and has a Mooney viscosity (ML 1 + 4/100 ° C) from 50 ± 4 on. The polymer Buna CB 24 is a cis 1,4-polybutadiene (Neodymium type) from Bayer AG with a cis 1,4 content of at least 97% and a Mooney viscosity from 44 ± 5. As an aromatic oil Naftolen ZD from Chemetall is used. Vulkanox 4020 it is 6PPD from Bayer AG and Protektor G35P is an ozone protection wax HB-Fuller GmbH. Vulkacit D / C (DPG) and Vulkacit CZ / EG (CBS) are commercial products from Bayer AG. Perkazit TBZTD is from the Akzo Chemie GmbH available.

The rubber compounds are in an internal mixer according to the mixing instructions in Table 6 manufactured.

Table 6

Table 3 shows the methods for rubber testing compiled.

The mixtures are vulcanized at 165 ° C for 20 min. Table 7 shows the results of gummitech African examination.

Table 7

How to look at the data in table 7 recognizes are due to the higher surface of the silicas of the invention Mooney viscosities of mixtures C and D. R3 slightly increased, but still better than the one that represents the state of the art, poorly processable reference mixture R4 with increased viscosity. With the exception of mixture R4 are the vulcanization characteristics (Dmax-Dmin, t90%, t10%) of all mixtures very similar. The tensile strengths too and voltage values of R3, C and D are comparable, while R4 a significantly higher one Hardness and Voltage value 100 has what a significantly higher silica network due to the poorer dispersion. Advantages of the blends C and D opposite R3 are elevated dynamic moduli E * 0 ° C and 60 ° C to recognize. These higher ones Rigidity is particularly important for high-speed passenger car and motorcycle tires are important as they improve dry handling and a higher one cornering stability Show. Despite the silicas used in mixtures C and D with higher CTAB surface are the tan δ values (60 ° C) advantageously across from the mixture R3 almost unchanged, which predicts a comparable rolling resistance while mixing R4 according to the prior art a significantly higher tan δ (60 ° C) and thus Shows rolling resistance. The good reinforcement in combination with the high CTAB surface area of the Silicas according to the invention enable one improved road abrasion of mixtures C and D. This improvement in road abrasion is also in use when using the high-surface area silicas according to the invention Natural rubber compounds, such as those used in truck tread compounds, reachable. Especially in combination with a high surface structure black like that N 121 excellent road abrasion can be achieved with truck tires. Just In this area of application there is also an improvement in cut & chip and chunking Behavior of particular interest and can be achieved by using the Realized high-surface area silicas according to the invention become.

Claims (19)

Precipitated silica, characterized by BET surface area 200 - 300 m ² / g CTAB surface area ≥ 170 m ² / g DBP number 200 - 300 g / (100 g) Sears number V ₂ 23 - 35 ml / (5 g). Precipitated silica according to claim 1, characterized in that the CTAB surface is a maximum of 300 m ² / g. Precipitated silica after one of the claims 1 or 2, characterized in that the precipitated silica has a WK coefficient of ≤ 3.4 (Relationship the peak height the particles in the size range that cannot be broken down by ultrasound 1.0 - 100 μm to the peak height of the mined Particles in the size range <1.0 μm). Precipitated silicas according to one of claims 1 to 3, characterized in that their surfaces are modified with organosilanes of the formula I to III: [SiR ¹ _n (RO) _r (Alk) _m (Ar) _p ] _p [B] (I), SiR ¹ _n (RO) _3-n (alkyl) (II), or SiR ¹ _n (RO) _3-n (alkenyl) (III), where B means: -SCN, -SH, -Cl, -NH ₂ , -OC (O) CHCH ₂ , -OC (O) C (CH ₃ ) CH ₂ (if q = 1) or -S _w - ( if q = 2), where B is chemically bound to alk, R and R ¹ : aliphatic, olefinic, aromatic or arylaromatic radical having 2 to 30 carbon atoms, which may optionally be substituted by the following groups: hydroxyl, amino , Alcoholate, cyanide, thiocyanide, halogen, sulfonic acid, sulfonic acid ester, thiol, benzoic acid, benzoic acid ester, carboxylic acid, carboxylic acid ester, acrylate, metacrylate, organosilane residue, where R and R ^{1 are} may have the same or different meaning or substitution. n: 0, 1 or 2, Alk: a divalent unbranched or branched hydrocarbon radical with 1 to 6 carbon atoms, m: 0 or 1, Ar: an aryl radical with 6 to 12 C atoms, preferably 6 C atoms, with the following Groups can be substituted: hydroxy, amino, alcoholate, cyanide, thiocyanide, halogen, sulfonic acid, sulfonic acid ester, thiol, benzoic acid, benzoic acid ester, carboxylic acid, carboxylic acid ester, acrylate, metacrylate, Organosilane residue, p: 0 or 1, with the proviso that p and n do not simultaneously mean 0, q: 1 or 2, w: a number from 2 to 8, r: 1, 2 or 3, with the proviso that r + n + m + p = 4, alkyl: a monovalent unbranched or branched saturated hydrocarbon radical having 1 to 20 carbon atoms, preferably 2 to 8 carbon atoms, alkenyl: a monovalent unbranched or branched unsaturated hydrocarbon radical having 2 to 20 carbon atoms, preferably 2 to 8 carbon atoms , Process for the preparation of a precipitated silica with a BET surface area of 200-300 m ² / g CTAB surface area ≥ 170 m ² / g DBP number 200-300 g / (100 g) Sears number V ₂ 23-35 ml / (5 g) where a) an aqueous solution of an organic and / or inorganic salt and / or Alkali or alkaline earth silicate and / or an organic and / or inorganic base with a pH ≥ 9 initially, b) water glass and an acidifying agent are metered into this template while stirring at 55-95 ° C. for 10-120 minutes, e) with sulfuric acid acidified to a pH of approx. 3.5 and f) filtered and dried. A method according to claim 5, characterized in that the Concentration of the organic and / or inorganic salt in the Template is 0.01 to 5 mol / l. A method according to claim 5 or 6, characterized in that that the steps between step b) and e) c) stopping the metering for 30 - 90 minutes while maintaining the temperature and d) simultaneous metering of water glass and acidulant at the same temperature with stirring for 20-20 minutes be performed. A method according to claim 7, characterized in that the acidifiers and / or the water glass in steps b) and d) in each case the same Have concentration or feed rate. A method according to claim 7, characterized in that the acidifiers and / or the water glass in steps b) and d) one each have a different concentration or feed rate. A method according to claim 9, characterized in that at same concentration of acidulant and / or the water glass in steps b) and d) their feed rate in step d) 125 - 140% the feed rate in step b). Method according to one of claims 5 to 10, characterized in that that for drying a current dryer, spray dryer, floor dryer, Belt dryer, rotary tube dryer, flash dryer, spin flash dryer or nozzle tower is used. A method according to claim 5 to 11, characterized in that after drying, granulation is carried out with a roller compactor. Method according to one of claims 5 to 12, characterized in that that while steps b) and / or d) adding an organic or inorganic Salt is done. Method according to one of claims 5 to 13, characterized in that that the granulated or ungranulated precipitated silica with Organosilanes in mixtures of 0.5 to 50 parts, based on 100 Parts of precipitated silica, especially 1 to 15 parts, based on 100 parts of precipitated silica modified, the reaction between precipitated silica and Organosilane during mixing (in situ) or outside by spraying and then Annealing the mixture or by mixing the organosilane and the silica suspension with following Drying and tempering is carried out. Elastomer mixtures, vulcanizable rubber mixtures and / or Vulcanizates containing the precipitated silica according to a of claims 1 to 4 included. Ripen, containing precipitated silica one of the claims 1 to 4. Tires for Commercial vehicles containing precipitated silica after one of the claims 1 to 4. Motorcycle tires containing precipitated silica one of the claims 1 to 4. Tire for high-speed vehicles containing precipitated silica according to one of the claims 1 to 4.