MXPA99008653A - Pulverulent rubber, in form of powder and containing modified fillers, procedure for its production and its use - Google Patents

Abstract

The invention relates to a process for the production of rubbers in the form of fine particles (rubber powder) by precipitation from aqueous mixtures containing the filler in the form of suspensions, water-soluble salts of a metal of Groups IIa , IIb, IIIa and VIII of the Periodic Table of the Elements and a rubber latex (polymer latex), aqueous emulsions of a rubber or rubber solution, in which process one or more organo-silicon compounds are emulsified in water contain at least one alkoxy group or optionally in the presence of a surface-active substance, or the said compounds are mixed under agitation directly or optionally with a surface-active substance together with the aqueous suspension of a filler in the form of fine particles enoxides or silicates, or a mixture of these charges at a temperature of 10 to 60 ° C, preferably at room temperature, divided in terms of in two parts the amount of this mixture expected to be incorporated into the rubber, referred to the total amount of

Description

PULVERULENT RUBBER, IN THE FORM OF DUST AND CONTAINING MODIFIED FILLERS, PROCEDURE FOR ITS PRODUCTION AND ITS USE DESCRIPTION OF THE INVENTION The present invention relates to a process for the production of rubbers in the form of powder containing fillers or fillers that have been modified by organosilicon compounds, and also refers to the powders thus produced. About the utility and purpose of the application of the powdered rubbers, as well as about possible procedures for their manufacture, a plurality of publications has appeared. The explanation of this interest for rubbers in the form of dust, is a forced consequence of the technique of processing of the rubber industry.

In this technique rubber mixtures are prepared based on a high input of time, energy and labor. The main cause of this is that rubber, as a raw material, comes in the form of bullets or bales (ballenformig) and the other components of the vulcanizable mixture have to be laboriously incorporated into the mixture. REF .: 31314 Comminution of the bale, intimate mixing with chemically inert fillers or fillers, mineral oils, softeners and vulcanization auxiliaries, takes place in rolling mills (Walzen) or in immersion mixers, in a multi-stage process . In general, between the stages, the mixture is cooled in a discontinuous production facility (Batch-off Anlage); in the absence of such installation, it is deposited on pallets or pallets as an intermediate deposit. The immersion mixers, or the rolling mills, are followed by extruders or by calendering processes. Now, starting from this very laborious / expensive technique of rubber processing, it is possible to derive a completely new processing technology. For this reason, the possibility of applying squeezable powdery rubbers has been studied for a long time, as this gives rise to the possibility of simply and quickly developing rubber mixtures as if they were thermoplastic synthetic materials in powder form. In DE-PS 2822 148 a process for the manufacture of a powdery rubber containing a filler or filler is disclosed.

According to said patent document, a rubber latex (for example, natural rubber), a rubber solution (for example, BR), or an aqueous emulsion of a synthetic rubber (for example, SBR) are mixed. with the aqueous emulsion of a filler, and the desired powder rubber is allowed to precipitate. In order to avoid the content of fillers, function of the granulometry, obtained by means of this method, variants have been presented such as DE-PS 3723 213 and DE-PS 3723 214 which form part of the current state of the art. According to the document DE-PS 3723213, it proceeds, in a two-stage process, to first integrate an amount equal to or greater than 50% of the filler, in the powdery rubber particles. In the second step, the rest of the load is applied or deposited on the so-called basic grains of the rubber. This can be considered as a variant of the dusting, since there is no bond between the load and the rubber. However, as E.T. Italiaander (Presentation: Technisc e Tagung der Rubber - Conferences Rubber Techniques of ACS, Anaheim, California, May 6 to 9, 1997 (GAK 6/1997 (50) 456-464), and regardless of the great future that in the Delphi Report (Delphi Report "Kunftige Herstellverfahren in der Gummiindustrie "- Future Procedures in the Manufacture of Rubber - Rubber Journal Vol. 154, No. 11, 20-34 (1972)) is predicted for rubber in the form of powder and granulate, and despite the numerous attempts that several accredited manufacturers of polymers have undertaken since the mid-70s to the early eighties to manufacture NBR in powder form, masterful games (asterbatches) of SBR - soot, and granulated NR, has survived the form of standard commercial provision of polymers, for rubber bales. One of the disadvantages of the known method is that for the adjustment of the granular diameter (10 μm) of the particles of the filler, considered necessary for the quality of the final product, a milling process is required. This not only implies a high consumption of energy, but also causes a damage in the structure of the load, which in addition to an active surface presents an important characteristic for the effectiveness of the rubber application. On the other hand, the workability of the product is affected according to the current state of the art, due to the fact that the particles stick to each other during storage. Now, under the document number P 198 16 972.8 a sedimentation process is presented by means of which suspensions of fillers or inerts modified by means of organo-silicon compounds are prepared, and said suspensions are introduced under agitation in the emulsion of the rubber, Next, The rubber powder is deposited or precipitated from this mixture. The object of the invention is to develop a process which, by means of a smaller number of steps in the process, makes it possible to obtain a rubber powder whose use is advantageous and which contains modified fillers. The object of the invention consists of a process for the preparation or production of rubbers in the form of fine particles (rubber powder) by their precipitation or sedimentation from aqueous emulsions containing the filler in the form of suspensions, water-soluble salts of a metal of the groups Ilia, Ilb, Illa and VIII of the Periodic Table of the Elements and a rubber latex, an aqueous emulsion of a rubber or a rubber solution. The process is characterized in that: a.- it is dissolved in water, or optionally emulsified in the presence of a surface-active substance, one or more organosilicon compounds, which contain at least one alkoxy group, or the compounds mentioned are directly mixed, optionally together with a surface-active substance, with the aqueous suspension of a charge of oxides or silicates in the form of fine particles or with a mixture of said charges, at a temperature of 10 to 60 degrees centigrade, preferaat room temperature , under agitation, for which it is divided in general terms into two parts the amount foreseen to be incorporated in the rubber, referred to the total amount of load; and b.- the first part is mixed with the polymer latex, the polymer emulsion or the polymer solution, respectively, the pH value of this mixture is decreased by an acid, especially a Lewis acid, to a pH value = 6.0 at pH = 4.5 (first part, first stage); c- the remaining part (second part, separating part) is added, causing the pH to fall even more, from 4.5 to 2.6, especially at a value of approximately 3.2 (second stage), so that the rubber present in the mixture, precipitated or sedimented together with the charge modified by the organosilicon compound (s); d.- the solid sedimented material is separated by methods known per se; e.- it is preferably subjected to washing, in order to adjust the pH value to a value of approximately 6 to 7, more acceptable for further processing; and f.- the rubber containing the load is dried. It is convenient that the drying takes place in a dryer in which the gases have an inlet temperature of 140 to 160 ° C and an outlet temperature of 50 to 70 ° C. The temperature of the product should not exceed 40 to 50 ° C. The duration and extent of the sedimentation process, which depend on the pH and the charge content, can be established in a simple manner within a measurement range. For a powdery rubber with a high degree of load (equal to or greater than 80 parts of phr charge), usually from 1 to 10 parts of this amount will be applied as a component remaining in the second stage during the precipitation of rubber in the form of dust.

If the rubber powder contains less than 80 parts of phr charge, for example in total only 50 parts phr, before the end of the precipitation process, we proceed to introduce more than 10 to 20 parts of the mixture into the mixture. this amount in the form of a suspension. In this way the charges are included and fixed in the outer zone of the grains (marginal zone) of the rubber in powder form. As a result, these components of the load are not applied externally to the individual rubber particles (see DE-PS 37 23213), but integrated into the surface of the rubber. Said distribution of the load, and the type of connection of the load in the mass of the rubber, have the effect of high drainability of the powder according to the invention, and prevent sticking during the storage of the powder, without losing them these properties by mechanical stresses such as hauling, silage, etc. As a filler, the soot, known in the rubber industry, is preferably applied, preferably in the form of fine particles (fluffy), which generally, without the need for a mechanical treatment, have an average grain size of 1 to 9 μm, preferably 1 to 8 μm, before being put in suspension. This facilitates the dispersion, so it is possible, without high energy consumption, to obtain aqueous suspensions with filler particles whose average diameter is clearly less than 10 μm. The precipitated silicas can be advantageously applied in the form of a washed filter cake, free of salt. «As metallic salts, we resort to those that come from the elements of the Groups lia, Ilb, Illa and VIII, of the Periodic Table of the Elements. This classification of the groups corresponds to the former recommendation of the IUPAC (See: Periodisch.es System der Elemente, Verlag Chemie, Weinheim, 1985). Typical representatives are magnesium chloride, zinc sulfate, aluminum chloride, aluminum sulfate, iron chloride, iron sulphate, cobalt nitrate and nickel sulfate, with aluminum salts being preferred. Aluminum sulfate and other Lewis acids are especially preferred. The salts are applied in an amount of 0.1 to 6.5 parts by weight per 100 parts by weight of rubber. The metal salts prove to be especially suitable for influencing favorably the granulometry of the precipitated products. To adjust the pH to the desired value, mineral acids such as, for example, sulfuric acid, phosphoric acid and hydrochloric acid are optionally used additionally., with sulfuric acid being preferred. However, carboxylic acids such as for example formic and acetic acid can also be applied. The amount of acid depends on the type and amount of metal salt soluble in water, of the filler, of the organosilane applied, of the rubber and of the alkali silicate optionally present. It can be easily determined by a few tentative trials. According to a preferred embodiment of the process according to the invention, up to 5 parts by weight per 100 parts by weight of silicic acid are additionally applied.

(Si02) in the form of an alkali silicate solution, preferably as water glass (Wasserglas) with a molar ratio; Na20 / Si02, from 2: 1 to 1: 4. In this case, the alkali silicate solution can be added to both the rubber component and the charge suspension. Addition to the rubber component is preferred, especially if the manufacture is made continuously. In general terms, the method according to the invention is carried out in the following manner; A charge suspension is prepared in such a way that a part, preferably equal to or greater than 50%, of the charge contained in the final product is dispersed in water, together with the metal salt, the organosilane compound and optionally with the alkali silicate solution, optionally in the presence of an emulsifier. The amount of total water applied depends on the type of load and the degree of completion. In general, the components of the suspension that are not soluble in water represent approximately 4 to 15% by weight. This value does not constitute a mandatory delimitation, and can be exceeded both in excess and by default. The maximum content is delimited by the possibility of pumping the suspension. The loading suspension, thus prepared, is then intimately mixed with the rubber latex which optionally contains an alkaline silicate solution or with the aqueous emulsion optionally containing an alkaline silicate solution, of a rubber solution (first part, first stage ). For this purpose, suitable stirring apparatuses are suitable, for example a paddle stirrer (Propellen-Ruhrer). After mixing, the pH is adjusted in the range of 6.0 to 4.5, maintaining the stirring process, and using an acid, preferably a Lewis acid, especially Al2 (S0). With this, the basic rubber grain is precipitated, with a constant content of filler and organosilane. The magnitude of this basic grain is controlled by the chosen amount of metal salt, in a range of 0.1 to 6.5 phr. The control is carried out in such a way that the smallest amount of metallic salt achieves the greatest granulation. The remaining amount of the load suspension (second part, separating part) is applied together with a further reduction of the pH value from 4.5 to 2.6, especially to approximately 3.2 (second stage), such that the rubber present in the mixture is precipitates together with the modified charge by the organo-silicon compound (s). The solids content of the applied latex is generally in the range of 20 to 25% by weight. The solids content of the rubber solutions is generally from 3 to 35%, that of the rubber emulsions is generally from 5 to 30% by weight. For the final preparation of powdered rubbers with a charge content equal to or greater than 100 phr, it is convenient to reduce the pH to a value of 2.5 before the phase separation. For this purpose it is convenient to use an acid chosen from the group of acids mentioned above. The process according to the invention can be carried out both continuously and discontinuously. It is convenient that the rubber powder, precipitated, be separated by a centrifuge and then dried until a residual water content is usually equal to or less than 1%, especially in a whirlpool bed dryer. The powder rubbers according to the invention are prepared by using one or more organosilicon compounds of the following general formulas: Si- (Alk) m- (Ar) p] q] [B] (I) Ran- (RO) 5_r? Si- (Alk) (II) or: R -. { RO) 3-n Si- (Alkenyl) (III) in which: B: represents-SCN, -SH, -Cl, -NH; (when q = 1) or -Sx- (when q = 2); R and R1: represent an alkyl group of 1 to 4 carbon atoms, branched or unbranched, phenyl radical, all the radicals R and R "may in each case have the same meaning or different meanings, preferably an alkyl group; R: represents an alkyl group of 1 to 4 carbon atoms, an alkoxy group of 1 to 4 carbon atoms, branched or non-branched; n is 0, 1 or 2; Alk; represents a linear or branched hydrocarbon radical, bivalent, with 1 to 6 carbon atoms; m: is worth 0 or 1; Ar: represents an arylene radical with 6 to 12 carbon atoms; p: is 0 or 1, provided that p and q do not simultaneously represent 0; x: is a number from 2 to 8; Alkyl: is a linear or branched hydrocarbon radical, unsaturated, bivalent, with 1 to 20 carbon atoms, preferably 2 to 8 carbon atoms; Alkenyl; a linear or branched hydrocarbon radical, monovalent, with 2 to 20 carbon atoms, preferably 2 to 8 carbon atoms. Said compositions, in the case of being soluble in water, are generally applied in the form of solutions and otherwise in the form of emulsions, chorus in this case, in which the emulsions can also be formed in the presence of the suspension. of silicic acid. It is preferable that the emulsion or suspension be prepared at room temperature, but temperatures of 10 to 60 ° C are also suitable. The concentration of the organosilicon composition (s) in the suspension is from 0.5 to 20% by weight, preferably from 5 to 12% by weight, based on the total amount of the applied load. The pH value of the emulsion or suspension, as well as the pH value of the charge suspension after the joint mixing of the emulsion, is in the environment of weakly acid to weakly alkaline, but preferably the pH has a value of about 7.

Under the term "water-soluble" used herein, it is to be understood that: After the combined mixing of the organo-silicon compound (without surface-active substance) with the suspension of the charge, around the particles of the charge, at the intervals desired for pH and concentration, no clear solution is formed. On the other hand, the separate phases consist of water, solids and organosilicon compound (s). The oligosulfur oligosilanes which correspond to the General Formula I given above are known per se and can be prepared by recourse to known methods. Examples of organosilanes of preferential application are, for example, the bis (trialkylsilyl-alkyl) oligo sulfides which can be prepared according to BE-PS 787 691, such as bis- (trimethoxy-, trietoxy-, trimethoxy-) , ethoxy-, -tripropoxy-, -tributhoxy-, -tri-i-propoxy- and -tri-i-butoxy-silyl-methyl) -oligo sulfides and in particular the di-, tri-, tetra-, penta.- , hexasulfides etc., in addition the bis- (3-trimethoxy-, -triethoxy-, -trimethoxyethoxy-, -tripropoxy- and -tri-n- and i-butoxy-ethyl) -oligo sulfides and especially the di-, tri -, tetra-, penta-, hexasulfides etc., in addition bis- (3-trimethoxy-, -triethoxy-, -trimethoxyethoxy-, -tripropoxy-, -tri-n-butoxy- and tri-i-butoxysilyl-propyl) -olifosulfides and especially again the di-, tri-, tetrasulfides, etc., up to the octa sulfuts, and in addition the corresponding bis- (3-trialkoxysilyl isobutyl) -oligosulphides, which correspond to the bis- (4-trialkoxysilyl butyl) -lol sulfides. Among these relatively simple selected organosilanes of General Formula I, bis- (3-trimethoxy-, -triethoxy- and tripropoxysilyl propyl) oligosulfides, and especially di-, tri-tetra - and penta-sulfides, especially the triethoxy compounds with 2, 3 or 4 sulfur atoms, and mixtures thereof. In the general formula, Alk represents a linear or branched hydrocarbon radical, preferably a saturated alkylene radical, with a linear hydrocarbon chain of 1 to 4 carbon atoms. Silanes whose structure has the following formula are also particularly suitable: [(C2H5O) 3 Si (CH2) 2 / Q -] [S ~ 3] and its methoxy analogues, which can be prepared according to DE-AS 25 58191. Said compounds are not soluble in water. As surface active substances, in this case, preference is given to surfactants (Tenside) non-ionogenic, cationic and anionic. Its concentration in the emulsion is from 1 to 15% by weight, preferably from 2 to 10% by weight, based on the amount of organosilicon compounds. Examples of surfactants of this type include alkylphenyl polyglycol ether, alkyl polyglycol ether, polyglycols, alkyltrimethyl ammonium salts, dialkyldimethylammonium salts, alkylbenzyltrimethylammonium salts, alkylbenzole sulfonates, alkyl hydrogen sulfates, alkyl sulfates. The precipitated natural fillers, to be modified, also in the form of two or more of these fillers, are inert fillers or fillers already known in the rubber industry. An essential requirement for its suitability is the presence of OH groups on the surface of the filler particles, which can react with the alkoxy groups of the organosilicon compounds. These are fillers in the form of oxides and silicates compatible with rubber, and which, for this use, have the necessary and known fineness. As natural silicates, kaolins or clays are especially suitable. Kieselguhr or diatomaceous earth can also be used. As fillers in oxide form, mention may be made, for example, of aluminum oxide, aluminum hydroxide or aluminum hydroxide trihydrate, and titanium dioxide. In this context, the term "modified fillers" means that the organosilane compounds are linked either by chemical modification (OH groups) or by adsorbent pathway on the surface. The groups bound by the adsorbent pathway are modified in chemically bound, through the drying step. The emulsion is mixed in the suspension of the filler, in such amounts, that the concentration of the organosilicon compound is from 0.5 to 20% by weight, preferably from 5 to 12% by weight, based on the amount of filler . The modified fillers contain from 0.5 to 20% by weight, preferably from 0.5 to 12% by weight, of the organosilicon compounds, based on the dry filler.

They are especially suitable for use in vulcanizable and moldable rubber mixtures. For the process according to the invention, it is convenient to use a filtering tower, free of salts, taken from precipitated silicic acid. Also suitable are suspensions such as those obtained in the production of natural fillers such as clays. In this way, a drying step, which consumes a lot of energy, is avoided, in contrast to the current state of the art. Silicic acids are known in the industrial activity of rubber. They generally have an N2 surface determined by the known BET method, from 35 to 700 nr / g, a CTAB surface of 30 to 500 m / g, and a DBP number of 150 to 400 ml / 100 g. The product according to the invention contains said silicic acids in an amount of from 5 to 250 parts, in particular from 20 to 100 parts, based on 100 parts of rubber. If they are natural white substances, such as clays (clays) and silicic chalk with a surface area of 2 to 35 m2 / g, they are applied in an amount of 5 to 350 parts, referred to 100 parts of rubber. Dusty rubbers containing fillers, and containing silicic acids and soot in the mixture, can also be prepared. However, the total amount of the charge does not exceed 250 phr. Soots are particularly suitable, such as they are usually used in rubber processing. These include blast furnace soot, gas and flame soot, with an iodine adsorption number of 5 to 1000 pr / g, a CTAB number of 15 to 600 itr / g, a DBP adsorption of 30 to 400 ml / 100 g and a number 24 M4 DBP from 50 to 370 ml / 100 g in an amount of 5 to 100 parts, especially from 20 to 100 parts, referred to 10Q rubber. As types of rubber that can be applied and that can be prepared as aqueous emulsions, the following species have been accredited, alone or in combination; natural rubber, SBR emulsion with a styrene component of 10 to 50%, butyl-acrylonitrile-rubber, butyl rubbers, terpolymers of ethylene, propylene (EPM), and non-conjugated dienes (EPDM), butadiene rubbers, SBR; prepared following the procedure of polymerization in solution, with styrene contents of 10 to 25%, as well as contents of 1,2-vinyl from 20 to 55%, and rubbers of isoprene, in particular 3,4-polyisoprene. In the case of polymerisates prepared by the solvent process, special precautions should be taken regarding the solvent content. In addition to the aforementioned rubbers, the following elastomers can be used, alone or mixed together; Carboxylic rubbers, epoxy rubbers, trans-polypentamers, halogenated butyl rubbers, 2-chlorobutadiene rubbers, ethylene-vinyl acetate copolymers, epichlorohydrins, optionally also chemically modified natural rubber, such as, for example, epoxidized types. The pulverulent rubbers according to the invention contain, in addition to the above-mentioned fillers, processing or vulcanization agents which are optionally known, such as zinc oxide, zinc stearate, stearic acid, polyalcohols, polyamines, softeners, anti-caustic agents. aging by heat, light or oxygen and ozone, hardening resins, flameproofing agents such as for example Al (OH) 3 and Mg (OH) ?, pigments, different cross-linking chemicals and possibly sulfur, in concentrations that are usual in the rubber technique. According to the invention, it is possible to prepare pulverulent rubber in the form of fine particles containing modified silicic acid by organosilicon compounds, which is still capable of draining even when subjected to mechanical stresses (for example, carrying and packing). Due to its fineness no grinding or comminution steps are necessary to achieve suspensions of fine particles. They then make it possible to obtain powdery rubbers in the form of fine particles, easy to make, and vulcanized with better properties. The following examples clarify the possibility of bringing the present invention into practice, as well as its advantages, without limiting them to the steps shown. Raw Materials Used in Preparation E-SBR: styrene-butadiene latex, for emulsions, with a content of 23.5% styrene (BSL) Si 69: Bis (triethoxysilylpropyl) tetrasulfan (Degussa AG) Si 75: Bis (triethoxysilylpropyl) disulfan (Degussa AG) Ultrasil VN3, Ultrasil VN3 (filter cake): precipitated silicic acid with an N_ (BET) surface area of 175 irr / g (Degussa AG), dried or as a filter cake, optionally granulated (large) Ultrasil 7000 , Ultrasil 7000 (filter cake): precipitated silicic acid with an N_ (BET) surface area of 175 nr / g and better dispersion properties (Degussa AG), drying or as filter cake, optionally granulated (large) Marlipal 1618/25: Emulsifier: polyethylene of fatty alcohols / glycol ether (Hülls AG) Example I Preparation of Powdered Rubber Based on E-SBR, Ultrasil 7000 and Si 69 Under shaking a stable suspension of 14.3 kg Ultrasil 7000, 1.58 kg Si 69 (corresponds to 11.3% referred to to silicic acid), 142 g of Marlipal 1618/25 (corresponds to 1%, based on silicic acid) in 225 liters of water, and then divided into two parts, in a 5: 1 ratio.

The larger part of the suspension is mixed with 94.3 liters of a 21.0% E-SBR latex emulsion under vigorous stirring and then the pH value is reduced to 5.0, by the addition of a solution of Al2 (S04) 3 to approximately 10%. To this first sedimentation step follows the addition of the second part, prepared as described above, the suspension with a subsequent reduction of the pH value to a final value of 3.7. After the sedimentation process, a mechanical separation of most of the water follows, followed by a drying step until a residual moisture content of less than 1% is achieved. The finished product, in powder form (EPB 1), contains 100 parts of E-SBR and 77 parts of Ultrasil 7000 / Si 69 (11.3%), determined by thermogravimetric analysis (TGA).

Example II Preparation of E-SBR-based Powder Rubber, Ultrasil 7000 Filter Cake and Si 69 Under agitation, a stable suspension of 59.0 kg Ultrasil 7000 filter cake, 1.60 kg of Si 69 is prepared (corresponds to 11.3% referred to the silicic acid), 140 g of Marlipal 1618/25 (corresponds to 1%, referred to the silicic acid) in 189 liters of water, and then fractionated in a 5: 1 ratio. The larger part of the suspension is mixed with 95.7 liters of a 20.5% E-SBR latex emulsion under vigorous stirring and then the pH value is reduced to 4.9 by the addition of a solution of A12. (S04) 3 to 10% approximately. To this first sedimentation step follows the addition of the second part, prepared as described above, the suspension with a subsequent reduction of the pH value to a final value of 3.4. After the sedimentation process, a mechanical separation of most of the water follows, followed by a drying step until a residual moisture content of less than 1% is achieved. The finished product, in powder form (EPB 2), contains 100 parts of E-SBR and 83 parts of Ultrasil 7000 (of the filter cake) / Si 69 (11.3%), (determined by TGA).

EXAMPLE III Preparation of Powdered Rubber on the Basis of E-SBR, Ultrasil VN3 and Si 69 A stable suspension of 13.9 kg of Ultrasil VN3, 1.55 kg of Si 69 (corresponds to 11.3% referred to above) is prepared under stirring. to silicic acid), 137 g of Marlipal 1618/25 (corresponds to 1%, based on silicic acid) in 267 liters of water, and then fractionated in a 5: 1 ratio. The greater part of the suspension is mixed with 94.7 liters of a 20.9% E-SBR latex emulsion under vigorous stirring and then the pH value is reduced to 5.2 by the addition of approximately 10% Al2 (S04) 3 solution. . To this first sedimentation step follows the addition of the second part, prepared as described above, the suspension with a subsequent reduction of the pH value to a final value of 3.5. After the sedimentation process, a mechanical separation of most of the water follows, followed by a drying step until a residual moisture content of less than 1% is achieved. The finished product, in powder form (EPB 3), contains 100 parts of E-SBR and 72 parts of Ultrasil VBN3 / YES 69 (11.3%), (determined by TGA).

EXAMPLE IV Preparation of Powdered Rubber Based on E-SBR, Ultrasil 7000 and Si 75 Under shaking a stable suspension of 14.6 kg of Ultrasil 7000, 1.59 kg of Si 75 is prepared (corresponds to 11.3% referred to to silicic acid), 142 g of Marlipal 1618/25 (corresponds to 1%, based on silicic acid) in 258 liters of water, and then fractionated in a 5: 1 ratio. The greater part of the suspension is mixed with 93, 8 liters of a 21.5% E-SBR latex emulsion under vigorous stirring and then the pH value is reduced to 5.1, by adding a solution of A12 (S04) 3 to approximately 10% . To this first sedimentation step follows the addition of the second part of the suspension (saturation agent), followed by the reduction of the pH value to a value of 3.3. After the sedimentation process, a mechanical separation of most of the water follows, followed by a drying step until a residual moisture content of less than 1% is achieved. The finished product, in powder form (EPB 4), contains 100 parts of E-SBR and 76 parts of Ultrasil 7000 / Si 75 (11.3%), determined by thermogravimetric analysis (TGA).

Example VI Preparation of E-SBR-based Powder Rubber, Ultrasil 7000 Filter Cake and Si 75 Under agitation a stable suspension of 61 kg Ultrasil 7000 filter cake, 1.63 kg Si 75 (corresponds to 11.3% referred to silicic acid), 140 g of Marlipal 1618/25 (corresponds to 1%, referred to silicic acid) in 195 liters of water, and then divided into a 5: 1 ratio. The greater part of the suspension is mixed with 96.2 liters of a 20.5% E-SBR latex emulsion under vigorous stirring and then the pH value is reduced to 4.8 by the addition of a solution of 12 (S? 4) 3 to about 10% This first step of sedimentation is followed by the addition of the second part of the suspension (saturation agent) with a subsequent reduction of the pH value to a value of 3.5. After the sedimentation process, a mechanical separation of the largest is followed part of the water, followed by a drying step until a residual moisture content of less than 1% is achieved. The finished product, in powder form (EPB 5), contains 100 parts of E-SBR and 80 parts of Ultrasil 7000 (of the filter cake) / Si 75 (11.3%), determined by ter gravimetric analysis (TGA ). For the own application of rubber technology the following products were applied: Chemical products SER 1500: styrene-butadiene rubber, with a stretch content of 23.5% Naftolen ZD: mineral oil softener, aromatic EPB1: powdery rubber, consisting of 100 parts of E-SBR 1500, 77 parts of Ultrasil 7000 / YES69 EPB2: powdery rubber, consisting of 100 parts of E-SBR 1500, 83 parts of Ultrasil 7000 (of filter cake) / Si69 EPB3: powdery rubber, consisting of 100 parts of E-SBR 1500, 72 parts of Ultrasil VN3 / YES69 EPB4: powdery rubber, consisting of 100 parts of E-SBR 1500, 76 parts of Ultrasil 7000 / YES75 EPB5: powdery rubber, consisting of 100 parts of E-SBR, 80 parts of Ultrasil 7000 (of the filter cake) / YES75 6 PPD: N- (1, 3-dimethylbutyl) -N-phenyl-p-phenylenendi mine CBS: benzothiazyl-2-cyclohexylsulfenamide DPG: diphenylguanidine The following test methods of the rubber technology were used: Mooney-DIN viscosity 53 523/3 Traction test on DIN 53 504 Shore hardness DIN 53 505 Resistance against tear propagation ASTM D 624 Abrasion DIN 53 516 Dispersion (Phillips) ISO / DIS 11 3545 Dispersion (roughness) DIN 4788 Elongation at break DIN 53504 Break energy DIN 53504 and A Comparison of the Table of Values, Own of the Technology of the Rubber, for the Product according to the Invention (Example of Preparation I) referred to a standard mixture. a.- Formulation b.- Mixing Procedure First Stage Immersion Mixer: GK 1.5 E; Volume 1.5 L; Friction 1: 1; Punch (Stempel) 5.5 bar Mixing 1 2 Degree of filling 0.55 0.6 RPM 50 40 Temp. of the flow pas. [° C] 60 60 0-0.5 'SBR 500 0 - 1' EPB, ZnO, Stearic acid, 0. 5-1 'Ultrasil 7000, Si oil, 6 PPD, wax 69, Oil, ZnO, Stearic acid, Wax 1 - 4 Mix and Extract Second Stage Immersion Mixer: GK 1-5 E; Volume 1.5 L; Friction 1: 1; Punch (Stempel) 5.5 bar; RPM 30; Grade of Filling 0.53; Temp. Flow Rate: 60 ° C Both Mixtures 0-1.5 'Stage 1 Batch, Accelerator, Sulfur 1.5' Extract and Remove the Skin c- Data Related to the Technology of the Rubber The rubber powder made with Latex E-SBR, Ultrasil 7000 and Si 69 differs from the conventional mixing modality by having higher resistance values, a more favorable abrasion, and a manifestly improved dispersion.

Example B Comparison of the Table of Values, Own of the Technology of the Rubber, for the Products in Accordance with the Invention EPB2 (E-SBR / Ultrasil VN3 / YES 69), EPB3 (E-SBR / Ultrasil VN3 Filter Cake / Si 69 ).

Formulation b.- First Stage Mixing Procedure Second Stage Immersion Mixer: GK 1 .5 E; Volume 1 5 L; Friction 1: 1; Punch (Stempel) 5. 5 bar, RPM 30; Grade of Filling 0.53; Temp. flow rate: 60 ° C Both Mixtures 0 - 1.5 'Stage Batch 1, Accelerator, Sulfur 1.5' Extract and Remove the Skin c- Data Related to the Technology of the Rubber Rubber powder made with Latex E-SBR, Ultrasil VN3 Filter Cake and Si 69 (EPB 3) differs from Ultrasil VN3 (EPD 2) by having higher resistance values, better abrasion, and excellent dispersion in the Compound.

Example C Comparison between EPB 4 (E-SBR / Ultrasil VN3 Filter Cake / Si 69), and EPB 5 (E-SBR / Ultrasil 7000 Filter Cake / Si 69). b.- Mixing Procedure First Stage Immersion Mixer: GK 1.5 E; Volume 1.5 L; Friction 1: 1; Punch (Stempel) 5.5 bar Mix 1.2 Degree of filling 0.6 RPM 40 Second Stage Immersion Mixer: GK 1.5 E; Volume 1.5 L; Friction 1: 1; Punch (Stempel) 5.5 bar; RPM 30; Grade of Filling 0.53; Temp. Flow Rate: 60 ° C Both Mixtures 0 - 1.5 'Stage Batch 1, Accelerator, Sulfur 1.5' Extract and Remove the Skin c- Data Related to the Technology of the Rubber The EPB 5 product with Ultrasil 7000 Filter Cake / Si 75 differs from the Ultrasil VN3 filter cake (EPD 4) by having higher resistance values, another elevation of abrasion resistance, and better dispersion.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects or products to which it refers.

Claims (14)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. Process for the production of rubbers in the form of fine particles (rubber powder) by means of their precipitation from aqueous mixtures containing the filler in the form of suspensions, water soluble salts of a metal of the groups Ilia, IIb, Illa and VIII of the Periodic Table of the Elements and a rubber latex (polymer latex), aqueous emulsions of a rubber or a rubber solution, characterized in that: a.- it is dissolved in water, or it is optionally emulsified in the presence of a substance surface-active one or more organosilicon compounds, containing at least one alkoxy group, or the said compounds are directly mixed, optionally together with a surface-active substance, with the aqueous suspension of a charge of oxides or silicates in form of fine particles or together with a mixture of said fillers, at a temperature of 10 to 60 degrees centigrade, preferably at room temperature, under agitation, dividing into t General terms in two parts, the expected amount of this mixture to be incorporated into the rubber, referring to the total amount of cargo; and b.- the first part is mixed with the polymer latex, the polymer emulsion or the polymer solution, respectively, the pH value of this mixture is decreased by an acid, especially a Lewis acid, to a pH value = 6.0 at pH = 4.5 (first part, first stage); c- the remaining part (second part, separating part) is added, causing the pH to fall even more, from 4.5 to 2.6, especially at a value of approximately 3.2 (second stage), so that the rubber present in the mixture, is precipitated together with the charge modified by the organosilicon compound (s); d.- the precipitated solid material is separated by methods known per se; e - is preferably subjected to washing, in order to adjust the pH value to a value of about 6 to 7, more acceptable for further processing; and f.- the rubber containing the load is dried.

2. Process according to claim 1, characterized in that one or more organosilicon compounds of the following general formulas are applied: [R! N- (0) 3-r, Si- (Alk)! T- (Ar) P] q] [B] (I) R1n- (R0) 3-n YES- (Alk) (II) R1 r-. { RO) 3-n Si- (Alkenyl) (III) in which: B: represents-SCN, -SH, -Cl, -NH (when q = 1) or -Sx- (when q = 2); R and R1: represent an alkyl group of 1 to 4 carbon atoms, branched or not, phenyl radical, all the radicals R and Ra in each case having the same meaning or different meanings, preferably an alkyl group; R: represents an alkyl group of 1 to 4 carbon atoms, an alkoxy group of 1 to 4 carbon atoms, branched or non-branched; n is 0, 1 or 2; Alk; represents a linear or branched hydrocarbon radical, bivalent, with 1 to 6 carbon atoms; m: is worth 0 or 1; Ar: represents an arylene radical with 6 to 12 carbon atoms; p: is 0 or 1, provided that p and q do not simultaneously represent 0; x: is a number from 2 to 8; Alkyl: is a linear or branched hydrocarbon radical, unsaturated, bivalent, with 1 to 20 carbon atoms, preferably 2 to 8 carbon atoms; Alkenyl; a linear or branched hydrocarbon radical, monovalent, with 2 to 20 carbon atoms, preferably 2 to 8 carbon atoms.

3. Process according to claims 1 or 2, characterized in that non-ionogenic, cationic or anionic surfactants are applied as surface-active substances.

4. Process according to claim 3, characterized in that the surfactants are applied in an amount of 1 to 15% by weight, especially 2 to 10% by weight, based on the amount of organosilicon compounds, in the. emulsion.

5. Process according to one or more of the preceding claims, characterized in that the concentration of the oleo-silicon compound in the suspension is from 0.3 to 15% by weight, based on the charge (atro).

6. Process according to claim 1, characterized in that the rubber powder is precipitated in the presence of an acid, preferably a Lewis acid, especially Al2 (S04) 3.

7. Process according to claim 3, characterized in that a surfactant of the class of polyethylene ethers of fatty alcohols or of polyethylene ethers of alkylphenols is applied.

8. Process according to one or more of the preceding claims, characterized in that in step a) the filter cake washed in a salt-free manner of a precipitated silicic acid is applied as a filler.

9. Process according to one or more of the preceding claims, characterized in that during the final elaboration natural fillers are used, especially clays, available solids are used.

10. Process according to claim 1, characterized in that in the first part according to step b) an amount equal to or greater than 50% of the total amount of charge intended to be introduced into the rubber powder is applied.

11. Process according to claim 1, characterized in that in the first part according to b), for an amount equal to or greater than 80% of phr charge (per one hundred parts of rubber), 90 to 99% of the amount is applied Total load expected to be introduced into the rubber powder.

12. Process according to one or more of the preceding claims, characterized in that an amount of soot usable in rubber technology is applied to the emulsion (suspension according to step a) or of the mixture according to step b), the desired amount.

13. Process according to claim 1, characterized in that it is to the emulsion, either to the suspension, either to the solution, according to claim 1, point a), or to the mixture generated according to points b) c), processing aids, anti-aging agents, activators, and / or chemical cross-linking agents and sulfur, customary in the rubber industry, are added in the usual amounts.

14. Rubbers in the form of fine particles (rubber powder) containing rubber, fillers, and processing aids, anti-aging agents, activators, and / or chemical crosslinking agents and sulfur, customary in industry, in usual amounts.