KR20100068490A - High-surface precipitation silicic acid - Google Patents

Abstract

The invention relates to a high-surface, highly dispersible precipitation silicic acid, a method for the production thereof and the use thereof as tyre filler material for commercial vehicles, motor bikes and high-speed vehicles.

Description

High-surface precipitation silicic acid

FIELD OF THE INVENTION The present invention relates to highly dispersible silicas with a large surface area, to methods of making such silicas and to their use as tire fillers for general purpose vehicles, motorcycles and high speed vehicles.

The use of precipitated silica in elastomer mixtures, such as tires, has been known many times. The use of silica in tires is quite demanding. Silica should be lightweight, easily dispersed in rubber, well bonded with polymer chains in rubber and other fillers, and have high wear resistance, such as the wear resistance of carbon black. Among other factors, apart from the dispersibility of silica, the specific surface area (BET or CTAB) and oil absorption (DBP) are important. The surface properties of the silica substantially determine the possible use of the silica, or the special use of the silica (eg, carrier systems or fillers for elastomer mixtures) requires special surface properties.

US Pat. No. 6,013,234 describes the preparation of precipitated silica having a BET surface area and a CTAB surface area of 100 to 350 m 2 / g, respectively. The silica is particularly suitable for incorporation into elastomer mixtures having a BET / CTAB ratio of 1 to 1.5. EP 0 937 755 describes various precipitated silicas having a BET surface area of about 180 to about 430 m 2 / g and a CTAB surface area of about 160 to 340 m 2 / g. These silicas are particularly suitable as carrier materials and have a BET / CTAB ratio of 1.1 to 1.3. EP 0 647 591 describes precipitated silicas having a BET surface area / CTAB surface area ratio of 0.8 to 1.1, which can be considered to have an absolute value of 350 m 2 / g or less in these surface areas. EP 0 643 015 can be used as an abrasive and / or thickening component of toothpastes having a BET surface area of 10 to 130 m 2 / g, CTAB surface area of 10 to 70 m 2 / g and a BET / CTAB ratio of approximately 1 to 5.21. Precipitated silica is described.

Silicas having the following properties, which are particularly suitable as fillers for elastomer mixtures (especially passenger car tires), are described in EP 0 901 986.

BET surface area 120 to 300 m 2 / g

CTAB surface area 100 to 300 m 2 / g

BET / CTAB ratio 0.8 to 1.3

Sears number V ₂ (Consume 0.1N NaOH) 6-25 ml / (5 g)

DBP numbers 150 to 300 g / (100 g)

WK factor less than 3.4

Degraded particle size less than 1.0 μm

Size of undecomposed particles 1.0 to 100 μm

Depending on the scope of application, the requirements for vehicle tires are very different. A very schematic distinction between passenger car tires and multi-purpose vehicle tires reveals the following minimal differences.

In the present invention, the term passenger car mainly means a passenger transport vehicle for private use, ie not a multipurpose vehicle such as a transport vehicle. Such a vehicle generally does not include a vehicle that runs at high speed, even if it can be applied according to a production form as a passenger car. In addition, the tires of these vehicles have other requirements as passenger car tires listed in the table.

In addition, motorcycle and high-speed car tires must withstand very high loads at high speeds and exhibit very good traction in wet and dry road conditions. However, good traction should not be associated with increased wear and high rolling resistance.

A different requirement for tires by vehicles is the corresponding effect of the filler used in the tire. Established over time, the mixture of silica and organosilicon compounds as a filler system for passenger car tires reduces rolling resistance, improves traction and reduces wear. These improved properties of multi-vehicle tires such as trucks (eg reduced rolling resistance) are often associated with lower fuel consumption. However, the different requirements placed on the tire by the vehicles mentioned above inevitably impose different requirements on the filler used.

Silica used in passenger car tires has been found to be unsuitable for use in truck tires, motorcycle tires and high-speed tires for passenger cars, because of different requirements profiles. It is therefore an object of the present invention to provide precipitated silica having a requirements profile, in particular a requirements profile suitable for these vehicles. The skilled person knows that when activated carbon black is used as a tire filler, the reinforcement of the tire is improved by increasing the surface area, thereby improving the wear resistance of the tire. However, the use of carbon black with a large surface area (CTAB surface area: greater than 130 m 2 / g) limits this packed mixture because of the heat accumulation (history recorded and measured according to the reference specified in DIN 53535 or DIN 53535). Phenomenon) increases considerably.

Precipitated silica with a large CTAB surface area has been found to be particularly good as a filler of elastomeric mixtures for general purpose vehicle tires and is currently suitable for motorcycle tires and tires for high speed cars.

Accordingly, it is an object of the present invention to have a BET surface area of 200 to 300 m 2 / g, CTAB surface area of at least 170 m 2 / g, a DBP number of 200 to 300 g / (100 g) and a Sears number V ₂ of 23 to 35 ml / (5 g) Phosphorus precipitated silica is to be provided.

The maximum CTAB surface area of the precipitated silica according to the invention may be 300 m 2 / g, in particular the CTAB surface area may be 170 to 220 m 2 / g or 245 to 300 m 2 / g.

Precipitated silicas according to the invention may exhibit properties independent of one another in the following preferred ranges:

DBP Absorption 230 to 300 g / (100 g), especially 230 to 280 g / (100 g)

WK coefficient 3.4 or less, preferably 3.0 or less, in particular 2.5 or less

Sears Water V ₂ 26-35 mL / (5 g)

The WK coefficient is defined as the ratio of the peak height of the particles (particle size: 1.0 to 100 μm) not disintegrated by the ultrasonic wave to the peak height of the particles disassembled by the ultrasonic wave (particle size: less than 1.0 μm) (FIG. 1).

EP 1 186 629 describes silica having a wide CTAB surface area suitable as a filler for tires. Thus, a description of the Sears number and the concentration of hydroxyl groups on the silica surface is not included in EP 1 186 629.

Still another object of the present invention is to provide a method for preparing an aqueous solution comprising: a) providing an aqueous solution having an organic salt and / or an inorganic salt, and / or an alkali metal silicate or alkaline earth metal silicate, and / or an organic base and / or an inorganic base having a pH of 9 or more,

b) metering the water glass and the acidifying agent into the solution while stirring the solution at 55-95 ° C. for 10-120 minutes, preferably 10-60 minutes,

e) acidifying with sulfuric acid to pH approximately 3.5 and

f) filtering and drying,

Process for producing precipitated silica having BET surface area of 200 to 300 m 2 / g, CTAB surface area of 170 m 2 / g or more, DBP number of 200 to 300 g / (100 g) and Sears number V ₂ of 23 to 35 ml / (5 g) To provide.

Silicas prepared according to the invention may exhibit the properties in the preferred ranges mentioned above.

The volume of the initial solution can be approximately 20, 30, 40, 50, 60, 70, 80 or 90% of the final settling volume. The basic compound to be added is especially selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal carbonates, alkali metal bicarbonates and alkali metal silicates. Preferably, water glass or sodium hydroxide solution is used. An initial solution without or with a small amount of electrolyte (salt) can be used, and the electrolyte can subsequently be added or used batchwise (preferably when precipitation begins).

Optionally other steps may be inserted in the method according to the invention. In this case, between step b) and e), c) discontinue metering for 30 to 90 minutes but maintaining the temperature and d) 20 to 120 minutes, preferably 20 to 80 minutes at this temperature. While stirring the solution, a step of metering water glass and an acidifying agent (especially sulfuric acid) into the solution is carried out.

It is also possible to optionally add organic or inorganic salts in steps b) and d). This can be done in solution or as a solid, in each case water glass and acidifiers (particularly sulfuric acid) are added continuously or batchwise. The salt may also be dissolved in one or both components and added together with these components.

Preferably, alkali metal salts or alkaline earth metal salts can be used as the inorganic salt. 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 -, HC0 3 -, OH - _{^{, TiO 3 2 -, ZrO 3}} 2 -, ZrO 4 4 -, Al0 2 -, Al 2 0 4 2 -, BO 4 3 -.

Methane salts, acetates and propionates are suitable as organic salts. Alkali metal ions or alkaline earth metal ions mentioned are referred to as cations. The concentration of these salts in the solution may be from 0.01 to 5 mol / l. Preferably, Na ₂ SO ₄ is used as the inorganic salt. In steps b) and d), the acidifying agent can be added in the same or different ways, ie at the same or different concentrations and / or metering rates.

Similarly, in the reaction of steps b) and d), water glass may be added in the same or different ways.

In a particular embodiment of the invention, in steps b) and d), the acidifying agent and the water glass component are added so that the metering rate in step d) is from 125 to 140% of the metering rate in step b), In these two steps, the components are each added in corresponding equimolar concentrations). Preferably, these components are added at the same concentration and at the same metering rate.

In addition to water glass (sodium silicate solution) other silicates such as potassium silicate or calcium silicate may be used. Sulfuric acid can be used as acidifying agent, but other acidifying agents can also be used, such as HCl, HNO ₃ , H ₃ PO ₄ or CO ₂ .

Filtration and drying methods of the silica according to the invention are well known to those skilled in the art and can be referred to, for example, from the documents mentioned above. Preferably, the precipitated silica is dried in an air-lift dryer, spray dryer, rack dryer, conveyor dryer, rotary dryer, flash dryer, spin flash dryer or nozzle dryer. These dryers also include operations with atomizers, single nozzles, dual nozzles or integrated fluidized beds. Preferably, the precipitated silica according to the invention is in the form of particles having an average diameter of 15 μm, preferably 80 μm, particularly preferably more than 200 μm after the drying step. The mean particle diameter is defined as the larger or smaller diameter represented by 50% by weight of the particles. After the drying step the silica may be ground with a roller compactor. In this case, an average particle diameter is 1 mm or more.

Preferably, the silica according to the invention is used as a tire for general purpose vehicles, trucks, high speed cars and motorcycles.

In the present invention, the multipurpose vehicle is any vehicle that requires a high level of running performance and wear resistance of the tire. As vehicles which require high running performance, tires for buses, trucks and / or transport vehicles and trailers are particularly mentioned. As vehicles requiring wear resistance such as cleat tear resistance, chipping and chucking, off-road vehicles, construction machinery, agricultural machinery, mining vehicles and tractor tires are mentioned. In particular, these vehicles are vehicles having an axial load of 1 m / t or more or vehicles having an allowable total weight of 2, 4, 7.5 or 15 m / t. In particular, the silica according to the invention can be used in heavy trucks or towing tires for these trailers. Such vehicles often have an axial load of at least 5 m / t and a tire diameter of at least 17 ".

ATV and truck tires are classified by speed. Silicas according to the invention are particularly suitable for (truck) tires with an acceptable speed of 80 to 140 km / h, which is indicated by the symbols F, G, J, K, L, M or N.

Tires for high speed vehicles (motor cycles or passenger cars) are tires whose allowable speed exceeds 180 km / h. These tires are tires (for passenger cars) indicated by the symbols S, T, U, H, V, W, Y and ZR.

Another object of the present invention is an elastomer mixture, vulcanizable rubber mixture and / or other vulcanizates containing silica according to the invention, for example pneumatic tires, tire treads, cable sheaths, hoses, drive belts, conveyors. It relates to molded bodies such as belts, roller coverings, tires, shoe soles, sealing rings and damping elements.

In addition, silica according to the present invention can be used in battery separators, as anti-sticking agents, as matting agents for coatings and coloring agents, as carriers for agricultural products and foodstuffs, as coatings for printing inks, in fire extinguisher powders, in plastics, In the field of non-contact printing, in paper pulp, as in the fields of personal hygiene and special applications, silica can be used in all commonly used applications.

When the silica according to the invention is used in the field of non-contact printing, for example an inkjet process, the silica according to the invention is used to prevent thickening of the printing ink or preventing splashing and blotting of the printing ink. To use; Used for papermaking as a filler, coating pigments, carbon paper and thermal paper; It can be used for thermal sublimation to prevent printing ink blotting, improve image and contrast, and improve spot focus and color clarity.

Personal hygiene applications are meant to mean the use of the silicas according to the invention, for example, as fillers or thickeners in the field of pharmacy or personal hygiene.

Silicas according to the invention may optionally be modified by silanes of the formulas (I) to (III) or organic silanes.

[Formula I]

[SiR ¹ _n (RO) _r (Alk) _m (Ar) _p ] _q [B]

[Formula II]

SiR ¹ _n (RO) _3-n (alkyl)

[Formula III]

SiR ¹ _n (RO) _3-n (alkenyl)

In the above formulas (I), (II) and (III),

B is -SCN, -SH, -Cl, -NH ₂ , -OC (O) CHCH ₂ , -OC (O) C (CH ₃ ) CH ₂ (when q is 1) or -S _w -where w is a number from 2 to 8 (when q is 2), B is chemically bonded to Alk,

R and R ¹ are aliphatic, olefinic, aromatic or aryl aromatic radicals having 2 to 30 carbon atoms, and R and R ¹ are hydroxy, amino, alcoholate, cyanide, thiocyanide, halogen, sulfonic acid, sulfonic acid ester , Thiol, benzoic acid, benzoic acid esters, carbonic acid, carboxylic acid esters, acrylates, methacrylates or organosilane radicals, which may be optionally substituted, and R and R ¹ may be the same or different radicals, or may be the same or different. Can,

n is 0, 1 or 2,

Alk is a divalent straight or branched chain hydrocarbon radical having 1 to 6 carbon atoms,

m is 0 or 1,

Ar is an aryl radical having 6 to 12 carbon atoms, preferably 6 carbon atoms, Ar is hydroxy, amino, alcoholate, cyanide, thiocyanide, halogen, sulfonic acid, sulfonic acid ester, thiol, benzoic acid, benzoic acid ester, May be substituted by carboxylic acid, carboxylic acid ester or organosilane radicals,

p is 0 or 1, provided that p and n are not 0 at the same time,

q is 1 or 2,

r is 1, 2 or 3, provided that r + n + m + p = 4,

Alkyl is a monovalent straight or branched chain saturated hydrocarbon radical having 1 to 20 carbon atoms, preferably 2 to 8 carbon atoms,

Alkenyl is a monovalent straight or branched chain unsaturated hydrocarbon radical having 2 to 20 carbon atoms, preferably 2 to 8 carbon atoms.

In addition, the silica according to the invention is SiR ² _{4 - n} X _n (Where n = 1, 2 or 3), [SiR ² _x X _y O] _z (where 0 ≦ x ≦ 2, 0 ≦ y ≦ 2, 3 ≦ z ≦ 10, and x + y = 2), [SiR ² _x X _y N] _z (where 0 ≦ x ≦ 2, 0 ≦ y ≦ 2, 3 ≦ z ≦ 10 and x + y = 2), SiR ² _n X _m OSiR ² _o X _p (Where 0 ≦ n ≦ 3, 0 ≦ m ≦ 3, 0 ≦ o ≦ 3, 0 ≦ p ≦ 3, n + m = 3 and o + p = 3), SiR ² _n X _m NSiR ² _o X _p (Where 0 ≦ n ≦ 3, 0 ≦ m ≦ 3, 0 ≦ o ≦ 3, 0 ≦ p ≦ 3, n + m = 3 and o + p = 3) and SiR ² _n X _m [SiR ² _x X _y O] _z SiR ² _o X _p where 0 ≦ n ≦ 3, 0 ≦ m ≦ 3, 0 ≦ x ≦ 2, 0 ≦ y ≦ 2, and 0 ≦ o ≦ 3, 0 ≦ p ≦ 3, 1 ≦ z ≦ 10000, n + m = 3, x + y = 2, o + p = 3, and the like. . These compounds may be straight, cyclic and branched silanes, silazanes and siloxane compounds. R ² is an alkyl and / or aryl radical having 1 to 20 carbon atoms, R ² is a hydroxy group, an amino group, a polyether (e.g. ethylene oxide and / or propylene oxide) and a halogenide group (e.g. fluoride) It may be substituted by a functional group such as. R ² may also contain groups such as alkoxy, alkenyl, alkynyl and aryl groups and sulfite groups. X may be a reactive group such as silanol, amino, thiol, halogenide, alkoxy, alkenyl and hydride groups.

SiR ² _n X _m [SiR ² _x X _y O] _z SiR ² _o X _p (where 0 ≦ n ≦ 3, 0 ≦ m ≦ 3, 0 ≦ x ≦ 2, 0 ≦ y ≦ 2, Linear polysiloxanes having a composition of 0 ≦ o ≦ 3, 0 ≦ p ≦ 3, 1 ≦ z ≦ 10000, n + m = 3, x + y = 2, and o + p = 3). Where R ² is preferably represented by methyl.

SiR ² _n X _m [SiR ² _x X _y O] _z SiR ² _o X _p (where 0 ≦ n ≦ 3, 0 ≦ m ≦ 1, 0 ≦ x ≦ 2, 0 ≦ y ≦ 2, Particularly preferred are polysiloxanes having a composition of 0 ≦ o ≦ 3, 0 ≦ p ≦ 1, 1 ≦ z ≦ 1000, n + m = 3, x + y = 2, and o + p = 3). Where R ² is preferably represented by methyl.

Optionally granulated precipitated silica, non-granulated precipitated silica, ground precipitated silica and / or unpulverized precipitated silica are mixed in 0.5 to 50 parts for 100 parts of precipitated silica, in particular 1 to 15 parts for 100 parts of precipitated silica And the reaction of the precipitated silica with the organic silane can be effected by spraying and subsequently tempering the mixture during the production of these mixtures (in the same reaction system) or outside the mixture production reaction system, or by organosilanes. By mixing the silica suspension with subsequent drying and tempering (e.g., according to German Patent No. 3 437 473 and German Patent Publication No. 19 609 619), or German Patent Publication No. 19 609 619 or Germany It is carried out according to the method described in patent application No. 40 04 781.

All difunctional silanes, which may have the effect of coupling to the filler containing silanol groups on the one hand and coupling to the polymer on the other hand, are basically suitable as organosilicon compounds. Typical amounts of organosilicon compounds are 1 to 10% by weight relative to the total amount of precipitated silica.

Examples of these organosilicon compounds are as follows: bis (3-triethoxysilylpropyl) tetrasulfane, bis (3-triethoxysilylpropyl) disulfane, vinyltrimethoxysilane, vinyltriethoxysilane, 3 -Mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane. Other organosilicon compounds are disclosed in WO 99/09036, European Patent Publication No. 1 108 231, German Patent Publication No. 10 137 809, German Patent Publication No. 10 163 945 and German Patent Publication No. 10 223 658 It is described in the issue.

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

Reinforcing fillers for elastomers, tire mixtures or vulcanizable rubber mixtures in the form of powders, spherical products or granules, according to the invention, in amounts of 5 to 200 parts per 100 parts of rubber, with or without silane modification. Can be mixed as. In the present invention, the rubber and elastomer mixture should be considered identical.

Apart from the mixtures containing only silica according to the invention, together with the above-mentioned organosilanes as fillers, the elastomer and rubber mixtures can be further filled with one or several or more or less strong fillers.

In addition, the following materials can be used as fillers:

-. Carbon Black: The carbon black used here is produced according to the lamp black, furnace or gas black process and has a BET surface area of 20 to 200 m 2 / g (eg SAF, ISAF, HSAF, HAF, FEF or GPF carbon). black). Carbon black may also contain heteroatoms such as silicon.

-. Highly dispersible pyrogenic silica is produced, for example, via flame hydrolysis of silicon halogenide. In addition, the silica may be present as an oxide mixed with other metal oxides (eg Al, Mg, Ca, Ba, Zn and titanium oxides).

-. Other commercially available silicas.

-. Synthetic silicates such as aluminum silicate, alkaline earth metal silicates (eg magnesium silicate or calcium silicate) having a BET surface area of 20 to 400 m 2 / g and a basic particle diameter of 10 to 400 nm.

-. Synthetic or natural aluminum oxide and aluminum hydroxide.

-. Natural silicates (eg kaolin) and other naturally occurring silicon dioxide compounds.

-. Glass fibers and glass fiber products (eg mats, strands) or microglass spheres.

-. Starch and modified starch forms.

-. Natural fillers such as clay and siliceous chalk.

Here, the blending ratio in the metering of the organic silane is adjusted according to the physical properties achieved in the processed rubber compound. The ratio of the silica according to the invention and the other fillers (also as mixtures) mentioned above is expected to be from 5 to 95% and is also realized within this range.

In a particularly preferred embodiment of the invention, if necessary, silica 10 consisting entirely or partly of silica according to the invention together with 0 to 100 parts by weight of carbon black and 1 to 10 parts by weight of organosilicon compounds, respectively, relative to 100 parts by weight of rubber To 150 parts by weight can be used to prepare the mixture.

Apart from silica, organosilanes and other fillers according to the invention, the elastomer forms another important rubber mixture component. They are prepared as homopolymers or by other rubbers such as natural rubber, polybutadiene (BR), polyisoprene (IR), in particular solvent polymerization processes and have a styrene content of 1 to 60% by weight, preferably 2 to 50 Styrene / butadiene copolymer (SBR), butyl rubber, isobutylene / isoprene copolymer (IIR) in weight percent, butadiene / acrylo in acrylonitrile content of 5 to 60 weight percent, preferably 10 to 50 weight percent As a blend with nitrile copolymer (NBR), partially hydrogenated or fully hydrogenated NBR rubber (HNBR), ethylene / propylene / diene copolymer (EPDM) and mixtures of these rubbers, oil-extended or oiled Natural elastomers and synthetic elastomers. The following additional rubbers are also contemplated as rubber mixtures with the abovementioned rubbers: carboxyl rubbers, epoxide rubbers, trans-polypentenamers, halogenated butyl rubbers; Rubber from 2-chlorobutadiene, ethylene vinyl acetate copolymer, ethylene propylene copolymer; And optionally, chemical derivatives of natural rubber and modified natural rubber. Preferred synthetic rubbers are described, for example, in W. Hofmann, "Kautschktechnologie", Genter Verlag, Stuttgart 1980. In order to produce the tires according to the invention, in particular, anionic polymerized L-SBR rubbers (solvent: SBR) having a glass transition temperature of at least -50 ° C and mixtures thereof with diene rubbers are advantageous.

Silicas according to the invention with or without silanes are suitable for all rubber applications, for example molded articles, tires, tire treads, conveyor belts, sealants, V-belts, hoses, shoe soles, cable sheaths, roller coverings, It can be used for damping elements and the like.

The incorporation of these silicas and the preparation of mixtures containing these silicas are generally carried out by methods commonly used in the rubber industry, ie in closed mixers or open roll mills, preferably at temperatures of 80 to 200 ° C. . Silica can be added as a powder, spherical product or granules. In addition, the silica according to the invention is not different from known white fillers.

The rubber vulcanizates according to the present invention can be used in conventional dosages such as other rubber aids, such as reaction promoters, anti-aging agents, heat stabilizers, light blockers, antioxidants, processing aids, plasticizers, electrodeposition agents, foaming agents, colorants, pigments, Waxes, extenders, organic acids, retardants, metal oxides and activators such as triethanolamine, polyethylene glycol, hexanetriol. These compounds are known in the rubber industry.

Rubber preparations can be used in known amounts, and in particular can be adjusted according to the particular application. Typical amounts are, for example, from 0.1 to 50% by weight relative to the rubber. Sulfur or sulfur donor materials can be used as vulcanizing agents. The rubber mixtures according to the invention may also contain vulcanization accelerators. Examples of suitable main promoters are mercaptobenzthiazole, sulfenamide, thiuram, dithiocarbamate to which 0.5 to 3% by weight is added. Examples of co-promoter include guanidine, thiourea and thiocarbonate to which 0.5 to 5% by weight is added. Sulfur can generally be used in amounts of 0.1 to 10% by weight, preferably 1 to 3% by weight relative to the rubber.

The silicas according to the invention can be used in rubbers which can be cured not only by peroxidation but also by accelerators and / or sulfur.

The vulcanization of the rubber mixtures according to the invention can, if necessary, be carried out at 100 to 200 ° C, preferably 130 to 180 ° C under pressure 10 to 200 bar. The rubber can be mixed with fillers, rubber aids and organosilicon compounds (if applicable) in known mixing equipment such as rolling mills, hermetic mixers and mixer-extruders.

Significantly reduced hysteresis with the use of silica according to the invention also provides the effect of meeting the requirements for surface area, which was not achievable due to the high hysteresis by carbon black and thus rolling resistance. To improve the effect.

The highly dispersible silica having a large surface area according to the invention has the advantage of providing rubber vulcanizates with improved wear resistance due to higher CTAB surface area. In addition, dry treatment is improved due to greater kinetic stiffness at 0 ° C. and 60 ° C., and rolling resistance, represented by a reduced tan δ value (60 ° C.), is reduced. Similar to carbon black, when using a high surface area highly dispersible silica according to the present invention, improved cut and chip behavior and chunking behavior is achieved, see definitions and other aspects of the literature [ See also: "New insights into the tear mechanism": This is what Dr. Tire Tech 2003 held in Hamburg. Published by W. Niedermeier].

Compared to similar rubber mixtures containing silica already known, the rubber mixtures according to the invention with improved low rolling resistance, improved wet and dry traction properties and good wear resistance are suitable for the production of tire treads. These tread mixtures with reduced rolling resistance, good wear resistance and improved cut and chip behavior and chunking behavior are not only suitable for high speed passenger car and motorcycle tires, but also for general purpose tires.

In addition, the silica according to the invention, which is a mixture with conventional tread carbon black without the addition of organosilicon compounds, is suitable for improving the cut and chip behavior of tires for construction machinery, agricultural machinery and mining vehicles.

In order to achieve a good series of values in the polymer mixture, the dispersibility of the precipitated silica in the matrix, polymer is very critical. This can be predicted by the WK coefficients.

1 is a schematic diagram of values necessary for calculating the WK coefficients.
The curve in FIG. 1 shows the maximum of the particle size distribution at 1.0 to 100 μm and another maximum of the particle size distribution at less than 1.0 μm. In the range of 1.0 to 100 μm, the peak represents the proportion of silica particles that did not degrade after sonication. These fairly coarse particles are poorly dispersed in the rubber mixture. In the range of less than 1.0 μm, the second peak with a much smaller particle size represents the proportion of silica particles crushed during the sonication process. These very small particles disperse very well in the rubber mixture.
Here, the WK coefficient is the peak value (B) of the undecomposed particles relative to the peak value (A) of the decomposed particles, the maximum value of which is in the range (A ') of less than 1.0 μm, the maximum value of which is in the range of 1.0 to 100 μm ( B ').
Thus, the WK coefficient is a measure of the "degradability" (dispersibility) of the precipitated silica. Precipitated silica can all be more easily dispersed, i.e., a smaller WK coefficient results in more decomposition of the particles when the precipitated silica is incorporated into the rubber.
The WK coefficient of the silica according to the invention is 3.4 or less, preferably 3.0 or less, particularly preferably 2.5 or less. Known precipitated silica is less dispersible because it has different WK coefficients and maximums of different particle size distributions as measured by Coulter LS 230.

The physicochemical data of the precipitated silica according to the invention is measured by the following method.

Moisture Measurement of Silica

According to the present method based on ISO 787-2, the volatile fraction of silica (hereinafter simply referred to as “wet”) is measured after drying at 105 ° C. for 2 hours. This drying loss mainly includes water moisture.

Execution

In a dry weighing bottle (8 cm in diameter, 3 cm in height) with a ground glass cover, 10 g of powdery spherical or granular silica is precisely weighed to 0.1 mg (weighed sample E). With the cover of the weighing bottle open, the sample is dried in a drying cabinet at 105 ± 2 ° C for 2 hours. The weighing bottle is closed and cooled to room temperature using silica gel as desiccant in the desiccator. The weight of the weighed fraction A is measured. The moisture (%) is determined by the formula [(E (g)-A (g)) x 100%] / [E (g)].

Silica Modified Sears  Can measure

As with measuring the number of free hydroxyl groups, the modified Sears number (hereinafter referred to as Sears number V ₂ ) can be determined by titrating the silica to pH 6-9 using potassium hydroxide solution. The basis of the measuring method is formed by the following chemical reaction, where "Si" -OH is a symbol representing the silanol group of silica.

"Si" -OH + NaCl ⇒ "Si" -ONa + HCl

HCl + KOH ⇒ KCl + H ₂ 0

Execution

10.00 g of powdered spherical or granular silica with 5 ± 1% of moisture is ground in an IKA M 20 universal mill (550 W; 20,000 rpm) for 60 seconds. If necessary, the moisture content of the initial material should be adjusted in a 105 ° C. drying cabinet or by uniform humidification. 2.50 g of the silica thus treated are weighed in a 250 ml titration vessel at room temperature and mixed with 60.0 ml of reagent grade methanol. After fully dispersing the sample, 40.0 mL of deionized water is added and they are all dispersed at 18,000 rpm for 30 seconds using Ultra Turrax T 25 (KV-18 G stirrer shaft, 18 mm diameter). Sample particles adhering to the vessel edge and stirrer in suspension are washed with 100 ml of deionized water and tempered to 25 ° C. in a constant temperature water bath. At room temperature, the pH meter (manufactured by Knick, 766 Calimatic pH meter type with temperature sensor) and pH electrode [single-rod measuring chain made by Schott, type N7680] were buffered (pH 7.00 and 9.00). First, the starting pH value of the suspension at 25 ° C. is measured with a pH meter and, according to the result, is adjusted to pH 6.00 by potassium hydroxide solution (0.1 mol / L) or hydrochloric acid solution (0.1 mol / L). The consumption (mL) of KOH solution or HCl solution up to pH 6.00 corresponds to V ₁ '. Then 20.0 mL of sodium chloride solution (250.00 g of reagent grade NaCl: charged to 1 L with deionized water) is added. The titration is continued to pH 9.00 with 0.1 mol / l KOH. The consumption (mL) of KOH solution up to pH 9.00 corresponds to V ₂ '. The volume V ₁ ′ or V ₂ ′ is then first normalized to 1 g of theoretically weighed sample and multiplied by 5 times to yield V ₁ and shea number V _2. [Unit: ml / (5 g)] is prepared.

BET Surface area  Measure

The specific nitrogen surface area (hereinafter BET surface area) of the powdery spherical or granular silica is measured according to ISO 5794-1 / Annex D using an area group (Strohlein, JUWE).

CTAB Surface area  Measure

The method is based on the adsorption of CTAB (N-hexadecyl-N, N, N-trimethylammonium bromide) to the “external” surface of silica, which is based on ASTM 3765 or NFT 45-007 (chapter 5.12.1.3). It is described on the basis as "rubber-effective surface". CTAB adsorption is carried out in aqueous solution with sonication under stirring. Residual non-adsorbed CTAB is measured by back titration using NDSS (dioctyl sodium sulfosuccinate solution, "Aerosol OT" solution) equipped with a titroprocessor, where the endpoint is the maximum opacity of the solution. Presented and measured by phototrode. In order to prevent CTAB crystallization, the temperature in all operating processes performed is 23-25 ° C. Back titration is based on the following equation.

(C ₂₀ H ₃₇ O ₄ ) SO ₃ Na + BrN (CH ₃ ) ₃ (C ₁₆ H ₃₃ ) ⇒ (C ₂₀ H ₃₇ O ₄ ) SO ₃ N (CH ₃ ) ₃ (C ₁₆ H ₃₃ ) + NaBr

    NDSS CTAB

Device

-. Titrator METTLER Toledo [DL 55 type] and titrator METTLER equipped with both pH electrodes [Mettler manufactured: DG 111 type] and phototrod (Mettler manufactured: DP 550 type) Toledo [DL 70 Type]

-. 100 ml polypropylene titration beaker

-. 150 ml glass titration vessel with lid

-. Pressure filtration device, content 100 ml

-. Membrane filter made of cellulose nitrate [pore size 0.1 μm, 47 mm Ø, for example Whatman (Grade No. 7181-004)]

reagent

Ready-to-use CTAB solution (0.015 mol / l in deionized water) and NDSS solution (0.00423 mol / l in deionized water) manufactured by Kraft, Duisburg, Germany [Class number 6056.4700 0.015 mol / l ; 0.00423 mol / l of grade number 6057.4700 NDSS solution] is purchased and stored at 25 ° C. and used within one month.

Execution

Blank titration

The consumption of NDSS solution to titrate 5 ml of CTAB solution should be tested 1 × day before each measurement. To this end, adjust the photoload to 1000 ± 20 mV before starting the titration (transparency: 100%). 5.00 ml of CTAB solution is correctly pipetted into a titration beaker and 50.0 ml of deionized water is added. While stirring, titration is carried out using a DL 55 titration apparatus using an NDSS solution, according to the measurement known to the skilled person, until the solution exhibits maximum opacity. The consumption V _I of the NDSS solution is measured in ml. All titrations should be performed in three measurements.

absorption

10.0 g of powdery spherical or granular silica with a moisture content of 5 ± 2% (if necessary, dry in a 105 ° C. drying cabinet or adjust the moisture content by uniform humidification) to a mill [Krups, Grind for 30 seconds on Model KM 75, Part No. 2030-70. 500.0 mg of the ground sample is correctly transferred to a 150 ml titration vessel equipped with a magnetic stirrer and 100.0 ml of CTAB solution is correctly added. The titration vessel is sealed with lid and stirred for 15 minutes with a magnetic stirrer. Stir the hydrophobic silica for up to 1 minute at 18,000 rpm using an Ultra Turrax T 25 stirrer (KV-18G stirrer shaft, 18 mm in diameter) until the hydrophobic silica is completely dispersed. The titration vessel is tightened to the titrator DL 70 and the pH value of the suspension is adjusted to 9 ± 0.05 using KOH (0.1 mol / l). The suspension is then sonicated for 4 minutes in a titration vessel in a 25 ° C. sonication batch (Sonorex RK 106 S, 35 kPa manufactured by Bandelin). Then immediately, pressure filtration through the membrane filter under nitrogen pressure of 1.2 bar. Discard 5 ml of the first procedure.

proper

5.00 ml of the remaining filtrate is pipetted into a 100 ml titration vessel and charged to 50.00 ml with deionized water. The titration beaker is tightened to the titration apparatus DL 55 and, with stirring, titration is performed using the NDSS solution until the maximum opacity is reached. The consumption V _II of the NDSS solution is measured in ml. All opacity should be performed by three measurements.

Calculation

Referring to the measurement,

V _I = Consumption of NDSS solution for titration of blank samples (ml)

V _II = Consumption of NDSS solution when the filtrate is used (ml)

Calculation method:

V _I / V _II = amount of CTAB in the blank sample / amount of CTAB still available in the filtrate sample

As a result, the equation regarding the adsorption amount N (g) of CTAB is as follows.

N = ((V _I -V _II ) × 5.5 g × 5 mL) / (V _I × 1000 mL)

Since only 5 ml from 100 ml of the filtrate is titrated, 0.5 g of silica with limited moisture is used, and the space requirement of 1 g of CTAB is 578,435 × 10 ⁻³ m 2, which is as follows.

CTAB surface area (water-not corrected) (m 2 / g) = (N × 20 × 578.435 m 2 / g) / (0.5g)

CTAB surface area (water-not corrected) (㎡ / g) = ((V _I -V _II ) × 636.2785 ㎡ / g) / V _I

The CTAB surface area is associated with silica that does not contain water, which is why the following corrections are made.

CTAB surface area (m 2 / g) = (CTAB surface area (water-not calibrated) m 2 / g × 100%) / (100%-moisture content%).

DBP  Measurement of absorption

The DBP absorbency (DBP number), a measure of the absorbent capacity of precipitated silica, is determined as follows based on DIN standard 53601.

Execution

Kneading chamber of Brabender Absorptometer "E" with 12.50 g of powder or spherical silica (optionally controlled by drying at 105 ° C. in a drying cabinet) with a water content of 0 to 10% Number 279061). For granules, a screened fraction of 3.15 to 1 mm (stainless steel sieve made by Retsch) is used (by gently pressing the granules through a screen with a pore diameter of 3.15 mm using a plastic spatula). At room temperature, with constant stirring (rotator speed of kneader blade: 125 rpm), dibutylphthalate is added dropwise into the mixture at a rate of 4 ml / min via "Dosimat Brabender T 90/50". Mixing with minimal power consumption is observed with reference to the digital display. At the end of the measurement, the mixture becomes "paste", which is indicated by a sharp rise in power consumption. If the number 600 is displayed (torque: 0.6 Nm), both the kneader and the DBP metering are powered off by electrical contact. A synchronous motor for DBP supply can be combined with a digital counter to read the DBP consumption (ml).

evaluation

The DBP uptake is expressed in g / (100g) and calculated from the measured DBP usage using the following equation. The density of DBP at 20 ° C. is typically 1.047 g / ml.

DBP Absorption (g) / (100g) = ((DBP Usage (mL)) × (Density of DBP (g / mL)) × 100) / (12.5 g)

The DBP absorption amount is limited for dry silica that does not contain water. In the case of using wet precipitated silica, this value should be corrected by the following calibration table. The correction corresponding to the water content is added to the experimentally measured DBP value, for example, 5.8% water content means the addition of 33 g / (100 g) to the DBP uptake.

Correction for Dibutylphthalate Absorption without Water

Measurement of WK Coefficient: Measurement of Aggregate Size Distribution by Laser Diffraction Method

WK  Measurement of modulus: laser On diffraction  Aggregate size distribution by

Sample manufacturing

If the silica to be measured is granules, 5 g of granular silica is added to the beaker and the coarse granule pieces are crushed with a pestle, but they are not powdered. 1.00 g of powder or spherical silica having a moisture content of 5 ± 1% prepared within 10 days in advance (optionally, the moisture content is dried at 105 ° C. in a drying cabinet or controlled by uniform humidification). Weigh in a mL centrifuge tube (height: 7 cm, diameter: 3 cm, depth of convex portion: 1 cm) and 20.0 g of a dispersion solution (hydrophilic silica: sodium hexametaphosphate (manufactured by Baker)). Charge to 1000 mL with deionized water / hydrophobic silica: 200.0 mL reagent grade ethanol containing 2.0 mL concentrated ammonia solution (25%) and 0.50 g of Triton X-100 (manufactured by Merck) . Charge to 1000 mL with deionized water] and mix with 20.0 mL. The centrifuge tube was then placed in a double wall glass cooling vessel (volume volume 80 ml, 9 cm in height, Ø3.4 cm) using cold water connected to tap water (20 ° C.), and the sample was placed on an ultrasonic finger [Bandelin]. Manufacture: horn DH 13 G and type UW 2200 with diamond plate Ø 13 mm] for 270 seconds. For this purpose, the power supply unit (Sonopuls: manufactured by Bandelin, HD 2200 type) of the ultrasonic finger is set to 50% power and 80% pulse (corresponding to 0.8 seconds of power and 0.2 seconds of stop). By water cooling, the temperature increase of the suspension is maintained at up to 8 ° C. The suspension is stirred with a magnetic stirrer to prevent settling of the suspension until the sample is added to the liquid module of the laser diffractometer within 15 minutes.

Execution

Before the measurement, the laser diffraction unit LS 230 (manufactured by Coulter) and the liquid module (LS variable speed fluid module plus integrated ultrasonic finger CV 181, manufactured by Coulter) were warmed up for 2 hours, The module (menu: "Control / Clean") is cleaned for 10 minutes. In the taskbar of the unit software, select the file window "Calculate Optimal Model" in the "Measure" menu and specify the refractive index as a * .rtf file as follows: Fluid refractive index B.I. Found = 1.332; Material refractive index found = 1.46; Predicted value = 0.1. In the file window "Measurement Cycle", the pump speed is set to 26% and the ultrasonic power of the integrated ultrasonic finger CV 181 is set to three. Point ultrasonics "with sample", "10 seconds before every measurement" and "during measurement" should be activated. In addition, the following features are selected in the file window: offset measurement, adjustment, background measurement, measurement concentration adjustment, sample information input, measurement information input, second measurement initiation, automatic cleaning, PIDS data.

Upon completion of the measurements and background measurements by the LS Sizing G15 standard (manufactured by Coulter), the sample is added. Suspended silica is added until the absorbance is 45-55% and the unit shows "OK". Measurements are performed at room temperature using the evaluation model of the * .rtf file defined above. Three replicates of 60 seconds each were performed with a standby time of 0 seconds for each of the silica samples. The software calculates the particle size distribution based on the volume distribution from the raw data curve, taking into account the Mie theory and the optical model by Fraunhofer. Typically, bimodal distribution curves are identified in form A at 0-1 μm (up to approximately 0.2 μm) and in form B at 1-100 μm (up to approximately 5 μm). According to FIG. 1, the WK coefficient can be determined therefrom and presented as the average of six individual measurements.

pH  Measure

A process based on DIN EN ISO 787-9 is used to measure the pH value of an aqueous suspension of silica at 20 ° C. To this end, an aqueous suspension of the sample to be measured is prepared. After stirring the suspension for a while, its pH value is measured with a precalibrated pH meter.

Execution

Before measuring pH, the pH meter (manufactured by Nike, type 766 Calimatic pH meter with temperature sensor) and the pH electrode (manufactured by Schott, single bar measuring chain, type N7680) were used daily at 20 ° C using a buffer. Correct. The calibration function should be chosen so that the two buffers used (buffers with pH of 4.00 and 7.00, buffers with pH of 7.00 and 9.00 and, if necessary, buffers with pH of 7.00 and 12.00) contain the expected pH values of the sample. If granules are used, first 20.0 g of silica are ground for 20 seconds in a mill (manufactured by Krupps, model KM 75, product number 2030-70).

5.00 g of powder or spherical silica with a water content of 5 ± 1% (if necessary, the moisture content is dried at 105 ° C. in a drying cabinet or controlled by uniform humidification before grinding required). ) Weigh in the correct size with 0.01 g accuracy in a wide-mouth glass flask. 95.0 ml of deionized water is added to the sample. The suspension is then stirred for 5 minutes in a closed vessel at room temperature using a mechanical stirrer (manufactured by Gerhardt, model LS10, 55 W, level 7). The pH value is measured immediately after the stirring process. For the measurement, the electrode is first washed with deionized water and then part of the suspension, which is immersed in the suspension. After adding the magnetic stirrer to the suspension, the pH measurement is carried out at a constant rate, forming some vortex in the suspension. If the pH meter shows a constant value, read the pH value from the display.

If hydrophobic silica is used, the process is carried out in a similar manner, but in this case, the ground sample with a water content of 5 ± 1% is weighed to an accurate scale of 0.01 g accuracy in a pre-tared wide glass flask. . 50.0 mL of reaction grade methanol and 50.0 mL of deionized water are added, then the suspension is stirred for 5 minutes in a closed vessel at room temperature using a mechanical stirrer (Gerhardt, Model LS10, 55 W, level 7). The pH value is measured while stirring the solution, but the measurement is carried out exactly 5 minutes later.

Determination of Solids Content in Filter Cakes

The volatile portion is removed at 105 ° C. and the solids content of the filter cake is measured according to this method.

Execution

100.00 g of the filter cake are weighed in a dry tared porcelain dish (diameter: 20 cm) (weighted fraction E). If necessary, the filter cake may be ground with a spatula to obtain a mass of 1 cm 3 or less. Dry the sample in a drying cabinet at 105 ± 2 ° C until the weight of the sample is constant. The sample is then cooled to room temperature in a desiccator using silica gel as a desiccant. The weight of the weighed fraction A is measured. Solid content (%) is determined according to the formula 100%-((E (g)-A (g)) x 100%) / (E (g)).

Measurement of electrical conductivity

The electrical conductivity (EC) of the silica is measured in an aqueous suspension.

Execution

When using granules, 20.0 g of silica is first ground in a mill (manufactured by Cropps, model KM 75, product no. 2030-70) for 20 seconds. 4.00 g of powder or spherical silica having a moisture content of 5 ± 1% (if necessary, the moisture is dried at 105 ° C. in a drying cabinet or controlled by uniform humidification before drying) and suspended in 50.0 ml of deionized water. Heat at 100 ° C. for 1 minute. Samples cooled to 20 ° C. are charged to exactly 100 ml, homogenized by stirring. The measuring cell of the conductivity measuring device LF 530 (manufactured by WTW) is washed with a small amount of sample before immersing the measuring cell LTA01 in the suspension. The value shown on the display corresponds to the conductivity at 20 ° C. when the external temperature sensor TFK 530 performs automatic temperature correction. The temperature coefficient and cell constant k should be tested each time before the measurement. 0.01 mol / l potassium chloride solution is used as calibration solution (EC = 1278 dl / cm at 20 ° C).

The following examples are intended to illustrate the invention in more detail without restricting the invention to these examples.

EXAMPLE

Example  One

41.60 L of water, 0.02 kg of water glass (density 1.348 kg / L: 27.1% SiO ₂ , 8.00% Na ₂ O) and 0.50 kg Na ₂ SO ₄ were made of high quality stainless steel with propeller stirring gear and double shell heater. Introduced into the reactor. Then, while stirring vigorously at 60 ° C. for 55 minutes, water glass 8.90 L / h and sulfuric acid (density 1.40 kg / L, H ₂ SO ₄ 50.6%) are added to about 2.10 L / h. The sulfuric acid is metered in so that the pH (measured at room temperature) in the reaction medium is mostly 9.0. Stop adding water glass and add until pH (measured at room temperature) is 3.3. The suspension obtained in this way is filtered in the usual way and washed with water. The filter cake with 18% solids content is liquefied with an aqueous sulfuric acid and shear unit. The silica slurry with a solid content of 16% is then spray dried. The BET surface area of the powdered product thus obtained was 238 m 2 / g, CTAB surface area was 199 m 2 / g, DBP absorption was 288 g / (100 g), Sears number V ₂ was 23.6 ml / (5 g), and conductivity Is 570 μS / cm.

Example  2

41.6 L of water, 0.02 kg of water glass (density 1.348 kg / L: 27.1% SiO ₂ , 8.00% Na ₂ O) and 0.5 kg Na ₂ SO ₄ were made of high quality stainless steel with propeller stirring gear and double shell heater. Introduced into the reactor. Then, while stirring vigorously at 64 ° C. for 56 minutes, water glass 8.95 L / h and sulfuric acid (density 1.40 kg / L, H ₂ SO ₄ 50.6%) were added about 2.05 L / h. The sulfuric acid is metered in so that the pH (measured at room temperature) in the reaction medium is mostly 9.0. Stop adding water glass and add until pH (measured at room temperature) is 3.3. The suspension obtained in this way is filtered in the usual way and washed with water. The filter cake with 18% solids content is liquefied with an aqueous sulfuric acid and shear unit. The silica slurry with a solid content of 16% is spray dried. The BET surface area of the powdered product thus obtained was 233 m 2 / g, the CTAB surface area was 193 m 2 / g, the DBP absorption was 276 g / (100 g), the Sears number V ₂ was 23.2 ml / (5 g), and the conductivity. Is 420 μS / cm.

Example  3

Silicas according to the invention obtained from Examples 1 and 2 were analyzed in SBR rubber mixture emulsions. As mentioned in the art, the tire tread silica ultrasil 7000 GR and Zesil 1205 MP with high surface area were selected for ease of dispersion. Ultrasil 7000 GR is precipitated silica (CTAB surface area: 160 ± 10 m 2 / g) (degussa AG) which can be easily dispersed. Zeosil 1205 MP is a large surface area silica (CTAB surface area of 200 ± 10 m 2 / g) manufactured by Rhodia. The formulations used for the rubber mixtures used are listed in Table 1. The unit phr means weight percent with respect to 100 parts of the crude rubber used. Mixtures A and B contain silica according to the invention and mixtures R1 and R2 are mixtures as discussed in the art. In order to evaluate the quality of the dispersion, the shear force introduced during the mixing process should be kept as constant as possible. However, the shear force can be kept constant by metering the silane according to the CTAB surface area, and it is necessary to make the sulfur correction correspond to the sulfur content of the silane in order to maintain the degree of crosslinking compared to the change in the amount of silane [see: H.-D. Luginsland, J.Frohlich, A.Wehmeier, paper No. 59, Providence / Rhode Island, USA: announced at the ACS-Meeting held April 24-27, 2001]. General methods for preparing rubber mixtures and their vulcanizates are described in the "Rubber Technology Handbook", W. Hofmann, Hanser Verlag 1994.

First step - R1 - - R2 - -A- -B- Buna 1500 100 100 100 100 Ultra Seal 7000 GR 60 --- --- --- Zeosil 1205 MP --- 60 --- --- Silica according to Example 1 --- --- 60 --- Silica according to example 2 --- --- --- 60 Si 69 4.80 5.77 5.86 5.68 Lenovo Pal NS 15 15 15 15 Stearic acid One One One One ZnO 3 3 3 3 Vulcan Knox HS / LG One One One One 2nd step Batch first step 3rd step Batch second stage Vulka Seat CZ / EG 1.0 1.0 1.0 1.0 Vulka Seat Thiuram / C 0.75 0.75 0.75 0.75 sulfur 0.68 0.57 0.57 0.58

Polymer Buna 1500 is a latex polymerized SBR copolymer (manufactured by Bayer AG) with a styrene content of 23.5% by weight. Si 69 is a coupling reagent bis (3-triethoxysilylpropyl) tetrasulfane (manufactured by Degussa AG). Renopal NS is a mineral oil manufactured by Fuchs Mineralowerke. Vulkanox HS / LG (TMQ), Vulkacit CZ / EG (CBS) and Vulkacit Thiuram / C (TMTD) are available from Bayer AG. do.

The rubber mixture is prepared in a closed mixer according to the method of Table 2.

First step: Set
Mixer

speed
Ram pressure
volume
Filling level
Flow temperature
Werner & Flyderer E-Type
(Werner & Pfleiderer E-Type)
70min ^-1
5.5 bar
1.58ℓ
0.56
70 ℃ Mixing process
0 to 1 minutes
1 to 3 minutes
3 to 4 minutes



4 minutes
4 to 5 minutes
5 minutes
Save
Buna 1500
1/2 filler, Si 69
1/2 filling material, stop
Component of the first stage
(Lenopal NS, Stearic Acid, ZnO, Vulcanox HS / LG)

washing
mix
exhaust
24 hours at room temperature Second step: Set

speed
Flow temperature
Filling level Except for speed, flow temperature and filling level
Same as the first step
80min ^-1
70 ℃
0.53 Mixing process
0 to 2 minutes
2 to 5 minutes

5 minutes
Save
Discontinue deployment of the first stage
By speed change, batch temperature
Maintained at 140 to 150 ° C
exhaust
4 hours at room temperature Third step: Set

speed
Filling level
Flow temperature Except for speed, fill level and flow temperature
Same as the first step
40min ^-1
0.51
40 ℃ Mixing process
0 to 2 minutes

2 minutes


Homogenization

Batch from the second step,
Vulka Sheet CZ / EG, Vulka Sheet Thiuram / C, Sulfur
Draining, and forming a sheet over the laboratory mixing mill

3 ^{* on} the left, 3 ^* cut and overlap on the right, and
Narrowing the roll nip by (1mm) 3 ^* and
Widen the roll nip (3.5mm) 3 ^* ,
Sheet passing and stretching

The rubber test method is summarized in Table 3.

Physical examination Standard / Condition ML 1 + 4, 100 ° C., third step (-) DIN 53523/3, ISO 667 Vulcanization Test, 165 ℃
Torque deviation
Dmax-Dmin (dNm)
t10% and t90% (minutes) DIN 53529/3, ISO 6502 Tensile Test on Ring, 23 ℃
Tensile Strength (MPa)
Yield strength (MPa)
Elongation at Break (%) DIN 53504, ISO 37 Shore-A hardness, 23 ° C (-) DIN 53505 Ball recoil (%) DIN EN ISO 8307,
Steel ball 19mm, 28g Dispersion Coefficient (%) Text reference Viscoelastic properties
0 and 60 ° C, 16 Hz, 50 N reserve and 25 N amplification
Record measurements after 2 minutes of test time, ie after 2 minutes of adjustment
Composite Modulus E ^* (MPa)
Loss modulus tan δ (-) DIN 53513, ISO 2856

The dispersion coefficient is measured optically-optically. The measurement can be carried out by the German Institute for Rubber Technology, Hannover, Germany. The process was also carried out at the DIK workshop held in Hannover, Germany, from 27 to 28 November 1997. It is described in "Bestimmung der Mischgute" published by H. Geisler. The mixture is vulcanized at 165 ° C. for 15 minutes. The technical test results of the rubber are shown in Table 4.

Crude mixture data - R1 - - R2 - -A- -B- ML 1 + 4 62 84 76 72 Dmax-Dmin 5.8 5.0 5.4 4.9 t10% 4.3 3.5 3.4 3.3 t90% 4.8 8.1 8.0 7.9 Vulcanizer  data The tensile strength 23.5 23.4 23.4 21.7 Yield strength 100% 1.5 2.0 1.5 1.4 Yield strength 300% 7.0 6.6 6.2 5.4 Breaking Shinto 640 670 660 680 Shore-A Hardness 57 65 60 58 Dispersion coefficient 96 78 96 94

As can be seen from the data in Table 4, the Mooney viscosity of mixtures A and B with silica according to the invention is higher than the Mooney viscosity of comparative mixture R1. This makes the silica network stronger because the surface area of the silica according to the invention is wider than the Ultrasil 7000 GR, the comparative silica. Compared to Zeosyl 1205 MP, which is the usual high surface area silica in comparative mixture R2, the viscosity is advantageously reduced, which means that the processability is improved. Due to the lack of acceleration control compared to the Ultrasil 7000 GR, the vulcanization time t90% is delayed, the surface area of the silica according to the invention can be increased, and the crosslinks represented by the torque deviation Dmax-Dmin are also reduced. Despite the lack of acceleration control, the tensile strength, yield strength and hardness of the mixtures A and B according to the invention appear to be well enhanced. While the hardness of the mixture of R1, A and B is similar, the hardness of the mixture R2 increases significantly. This shows that conventional high surface area silica was improperly dispersed in R2. The dispersion quality of mixtures A and B at 90% or more is very good and reaches the level of highly dispersible silica in R1 while the dispersion in R2 with high surface area silica according to the prior art in the art is quite poor.

Example  4

Silicas according to the invention obtained from Examples 1 and 2 were analyzed in S-SBR / BR rubber mixtures. Silica Ultrasil 7000 GR and high surface area Zeosyl 1205 MP were chosen as silica according to the prior art.

The formulation used for the rubber mixture used is shown in Table 5. Ultrasil 7000 GR, a comparative silica, was modified with 6.4 phr of Si 69. In order to take into account the high surface area of the comparative silica Zeoli 1205 MP and the silica according to the invention in the mixtures R4, C and D, the amount of silane was increased to 8 phr, thus reducing the amount of sulfur. Sulfur correction corresponding to the sulfur content of the silane is required. See H.-D. Luginsland, J.Frohlich, A.Wehmeier, paper No. 59, Providence / Rhode Island, USA: announced at the ACS-Meeting held April 24-27, 2001].

First step - R3 - - R4 - -C- -D- Buna VSL 5025-1 96 96 96 96 Buna CB 24 30 30 30 30 Ultra Seal 7000 GR 80 --- --- --- Zeosil 1205 MP --- 80 --- --- Silica according to Example 1 --- --- 80 --- Silica according to example 2 --- --- --- 80 Si 69 6.4 8.0 8.0 8.0 ZnO 2 2 2 2 Stearic acid 2 2 2 2 Naphthylene ZD 10 10 10 10 Vulcan Knox 4020 1.5 1.5 1.5 1.5 Protector G35P One One One One 2nd step Batch level 1 3rd step Batch level 2 Vulka Seat D / C 2.0 2.0 2.0 2.0 Vulka Seat CZ / EG 1.5 1.5 1.5 1.5 Perazette TBZTD 0.2 0.2 0.2 0.2 sulfur 1.51 1.33 1.33 1.33

Polymer VSL 5025-1 is a solution SBR copolymer (manufactured by Bayer AG) having a styrene content of 25% by weight and a butadiene content of 75% by weight. The copolymer contains 37.5 phr of oil and has a Mooney viscosity (ML 1 + 4/100 ° C.) of 50 ± 4. The polymer moiety, CB 24, is a cis 1,4-polybutadiene (neodymium form) having a cis 1,4 content of at least 97% and a Mooney viscosity of 44 ± 5 (manufactured by Bayer AG). Naphtolen ZD (manufactured by Chemetall) is used as aromatic oil. Vulcanox 4020 is 6PPD (manufactured by Bayer AG) and Protektor G35P is an antioxidant wax (manufactured by HB-Fuller GmbH). Vulkasheet D / C (DPG) and Vulkasheet CZ / EG (CBS) are commercially available from Bayer AG. Perkazit TBZTD is available from Akzo Chemie GmbH.

The rubber mixture is prepared in a closed mixer according to the method of Table 6.

First step: Set
Mixer
speed
Ram pressure
volume
Filling level
Flow temperature
Werner & Flyderer E-Type
70min ^-1
5.5 bar
1.58ℓ
0.56
80 ℃ Mixing process
0 to 1 minutes
1 to 3 minutes
3 to 4 minutes
4 minutes
4 to 5 minutes
Save
Buna VSL 5025-1 + Buna CB 24
1/2 filler ZnO, stearic acid, naphthylene ZD, Si 69
1/2 Filler, Vulcanox 4020, Protector G35P
washing
Mixing and discharging
24 hours at room temperature Second step: Set
speed
Filling level Same as step 1 except speed and charge level
80min ^-1
0.53 Mixing process
0 to 2 minutes
2 to 5 minutes

5 minutes
Save
Discontinue deployment of the first stage
By speed change, batch temperature
Maintained at 140 to 150 ° C
exhaust
4 hours at room temperature Third step: Set

speed
Filling level
Flow temperature Except for speed, fill level and flow temperature
Same as the first step
40min ^-1
0.51
50 ℃ Mixing process
0 to 2 minutes

2 minutes


Homogenization

Batch from the second step,
Vulka Sheet D / C, Vulka Sheet CZ / EG, Percite TBZTD and Sulfur
Draining, and forming a sheet over the laboratory mixing mill
(Diameter 200mm, length 450mm, flow temperature 50 ℃)
3 ^{* on} the left, 3 ^* cut and overlap on the right, and
Narrowing the roll nip by (1mm) 8 ^* and
Widen the roll nip (3.5mm) 3 ^* ,
Sheet passing and stretching

The rubber test method is summarized in Table 3.

The mixture is vulcanized at 165 ° C. for 20 minutes. The technical test results of the rubber are shown in Table 7.

Crude mixture data - R3 - - R4 - -C- -D- ML 1 + 4 60 82 72 69 Dmax-Dmin
t10%
t90% 16.4
1.5
7.4 19.0
0.7
6.7 16.8
1.2
8.6 17.5
1.2
8.0 Vulcanizer  data The tensile strength
Yield strength 100%
Yield strength 300%
Breaking Shinto 13.3
1.8
10.4
350 15.4
3.0
12.1
350 12.4
1.9
9.8
350 13.6
1.8
9.5
370 Shore-A Hardness 60 71 63 63 Ball recoil, 60 ℃ 60.9 56.2 60.9 59.3 E ^* (0 ℃)
E ^* (60 ℃)
tanδ (0 ° C)
tanδ (60 ° C) 18.0
7.7
0.458
0.122 26.4
8.8
0.527
0.145 23.2
9.1
0.440
0.129 23.0
8.8
0.443
0.125 Dispersion coefficient 98 81 91 95

As can be seen from the data in Table 7, since the surface area of the silica according to the invention is wider, the Mooney viscosity of the mixtures C and D is somewhat higher than R3, but the viscosity which can be poorly processed increased. Still better than comparative mixture R4 which represents the prior art in the art. The vulcanization properties (Dmax-Dmin, t90%, t10%) of all mixtures except mixture R4 are very similar. The yield strengths of the mixtures R3, C and D are almost equal, while R4 has a much higher hardness, a yield strength of 100% and shows a higher silica network due to inferior dispersion. The advantages of mixtures C and D over R3 can be seen at increased dynamic modulus E ^* (0 ° C.) and (60 ° C.). Their greater stiffness is particularly important in high speed passenger car and motorcycle tires because they demonstrate improved traction and higher cornering stability in dry conditions. Although the silica contained in the mixtures C and D has a larger CTAB surface area, the tan δ (60 ° C.) value is favorably hardly changed compared to the mixture R3 and thus similar cloud resistance can be expected, while The rolling resistance is greater because the tan δ (60 ° C.) value of the mixture R4 according to the prior art is quite large. Good reinforcement combined with the high CTAB surface area of the silica according to the invention can improve the road wear of the mixtures C and D. In addition, this improvement in road wearability can be achieved when the high surface area silica according to the invention is used in natural rubber mixtures (e.g., the silica is used in truck tire tread mixtures). In particular, with high surface area high structure carbon black (eg N121), excellent road wear can be achieved in truck tires. In particular, improvements in cut and chip behavior and chunking behavior are of particular interest in the art, which can be realized by using silica having a high surface area according to the invention.

Claims (9)

BET surface area is 200 to 300 m 2 / g,
CTAB surface area is at least 170 m 2 / g,
DBP number is between 200 and 300 g / (100 g),
Precipitated silica, characterized in that the Sears number V ₂ is from 23 to 35 ml / (5 g). The precipitated silica of claim 1, wherein the CTAB surface area is 300 m 2 / g or less. The peak height of particles (particle size: 1.0 to 100 μm) which is not decomposed by ultrasonic wave relative to the peak height of particles decomposed by ultrasonic wave (particle size: less than 1.0 μm). Precipitated silica, characterized in that the WK coefficient defined by the ratio of 3.4 or less. The precipitated silica according to claim 1 or 2, wherein the surface is modified by at least one organosilane selected from the group consisting of formulas (I) to (III).
Formula I
[SiR ¹ _n (RO) _r (Alk) _m (Ar) _p ] _q [B]
Formula II
SiR ¹ _n (RO) _3-n (alkyl)
Formula III
SiR ¹ _n (RO) _3-n (alkenyl)
In the above formulas (I), (II) and (III),
B is -SCN, -SH, -Cl, -NH ₂ , -OC (O) CHCH ₂ , -OC (O) C (CH ₃ ) CH ₂ (when q is 1) or -S _w -where w is a number from 2 to 8 (when q is 2), B is chemically bonded to Alk,
R and R ¹ are hydroxy, amino, alcoholate, cyanide, thiocyanide, halogen, sulfonic acid, sulfonic acid ester, thiol, benzoic acid, benzoic acid ester, carboxylic acid, carboxylic acid ester, acrylate, methacrylate or organosilane Are aliphatic, olefinic, aromatic or aryl aromatic radicals having 2 to 30 carbon atoms, which may be optionally substituted by radicals, R and R ¹ may be the same or different radicals or may be substituted identically or differently,
n is 0, 1 or 2,
Alk is a divalent straight or branched chain hydrocarbon radical having 1 to 6 carbon atoms,
m is 0 or 1,
Ar is hydroxy, amino, alcoholate, cyanide, thiocyanide, halogen, sulfonic acid, sulfonic acid ester, thiol, benzoic acid, benzoic acid ester, carboxylic acid, carboxylic acid ester, acrylate, methacrylate or organosilane radical Aryl radical of 6 to 12 carbon atoms which may be substituted,
p is 0 or 1, p and n are not 0 at the same time,
q is 1 or 2,
r is 1, 2 or 3, r + n + m + p = 4,
Alkyl is a monovalent straight or branched chain saturated hydrocarbon radical having 1 to 20 carbon atoms,
Alkenyl is a monovalent straight or branched chain unsaturated hydrocarbon radical having 2 to 20 carbon atoms. Elastomeric mixture, vulcanizable rubber mixture or vulcanizate containing precipitated silica according to claim 1. A tire containing the precipitated silica according to claim 1. A commercial vehicle tire containing the precipitated silica according to claim 1. A motorcycle tire comprising the precipitated silica according to claim 1. A high speed vehicle tire containing the precipitated silica according to claim 1.

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